Sattelle DB


Full name : Sattelle David B

First name : David B

Mail : Wolfson Institute for Biomedical Research, Cruciform Building, University College London, Gower Street, London WC1E 6BT

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Country : United Kingdom

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References (131)

Title : Aedes aegypti CCEae3A carboxylase expression confers carbamate, organophosphate and limited pyrethroid resistance in a model transgenic mosquito - Poulton_2024_PLoS.Negl.Trop.Dis_18_e0011595
Author(s) : Poulton BC , Colman F , Anthousi A , Sattelle DB , Lycett GJ
Ref : PLoS Negl Trop Dis , 18 :e0011595 , 2024
Abstract : Insecticide resistance is a serious threat to our ability to control mosquito vectors which transmit pathogens including malaria parasites and arboviruses. Understanding the underlying mechanisms is an essential first step in tackling the challenges presented by resistance. This study aimed to functionally characterise the carboxylesterase, CCEae3A, the elevated expression of which has been implicated in temephos resistance in Aedes aegypti and Aedes albopictus larvae. Using our GAL4/UAS expression system, already established in insecticide-sensitive Anopheles gambiae mosquitoes, we produced transgenic An. gambiae mosquitoes that express an Ae. aegypti CCEae3A ubiquitously. This new transgenic line permits examination of CCEae3A expression in a background in which there is not a clear orthologue in Vectorbase and allows comparison with existing An. gambiae GAL4-UAS lines. Insecticide resistance profiling of these transgenic An. gambiae larvae indicated significant increases in resistance ratio for three organophosphate insecticides, temephos (6), chloropyriphos (6.6) and fenthion (3.2) when compared to the parental strain. Cross resistance to adulticides from three major insecticide classes: organophosphates (malathion, fenitrothion and pirimiphos methyl), carbamates (bendiocarb and propoxur) and pyrethroid (alpha-cypermethrin) was also detected. Resistance to certain organophosphates and carbamates validates conclusions drawn from previous expression and phenotypic data. However, detection of resistance to pirimiphos methyl and alphacypermethrin has not previously been formally associated with CCEae3A, despite occurring in Ae. aegypti strains where this gene was upregulated. Our findings highlight the importance of characterising individual resistance mechanisms, thereby ensuring accurate information is used to guide future vector control strategies.
ESTHER : Poulton_2024_PLoS.Negl.Trop.Dis_18_e0011595
PubMedSearch : Poulton_2024_PLoS.Negl.Trop.Dis_18_e0011595
PubMedID: 38377131
Gene_locus related to this paper: aedae-q17b31

Title : A single amino acid polymorphism in the Drosophila melanogaster Dalpha1 (ALS) subunit enhances neonicotinoid efficacy at Dalpha1-chicken beta2 hybrid nicotinic acetylcholine receptor expressed in Xenopus laevis oocytes - Ihara_2014_Biosci.Biotechnol.Biochem_78_543
Author(s) : Ihara M , Shimazu N , Utsunomiya M , Akamatsu M , Sattelle DB , Matsuda K
Ref : Biosci Biotechnol Biochem , 78 :543 , 2014
Abstract : Polymorphisms are sometimes observed in native insect nicotinic acetylcholine receptor (nAChR) subunits, which are important insecticide targets, yet little is known of their impact on insecticide actions. Here we investigated the effects of a polymorphism involving the substitution of histidine108 by leucine in the Drosophila melanogaster Dalpha1 subunit on the agonist actions of the neurotransmitter acetylcholine (ACh) and two commercial neonicotinoid insecticides (imidacloprid and clothianidin). There was no significant impact of the H108L substitution on either the ACh EC50, the concentration leading to a half maximal ACh response, or the maximum current amplitude in response at 10 muM ACh, of the Dalpha1-chicken beta2 nAChR expressed in Xenopus laevis oocytes. However, the response amplitudes to imidacloprid and clothianidin were significantly enhanced, indicating a role of His108 in the selective interactions of Dalpha1 with these neonicotinoids.
ESTHER : Ihara_2014_Biosci.Biotechnol.Biochem_78_543
PubMedSearch : Ihara_2014_Biosci.Biotechnol.Biochem_78_543
PubMedID: 25036948

Title : Genome of the house fly, Musca domestica L., a global vector of diseases with adaptations to a septic environment - Scott_2014_Genome.Biol_15_466
Author(s) : Scott JG , Warren WC , Beukeboom LW , Bopp D , Clark AG , Giers SD , Hediger M , Jones AK , Kasai S , Leichter CA , Li M , Meisel RP , Minx P , Murphy TD , Nelson DR , Reid WR , Rinkevich FD , Robertson HM , Sackton TB , Sattelle DB , Thibaud-Nissen F , Tomlinson C , van de Zande L , Walden KK , Wilson RK , Liu N
Ref : Genome Biol , 15 :466 , 2014
Abstract : BACKGROUND: Adult house flies, Musca domestica L., are mechanical vectors of more than 100 devastating diseases that have severe consequences for human and animal health. House fly larvae play a vital role as decomposers of animal wastes, and thus live in intimate association with many animal pathogens. RESULTS: We have sequenced and analyzed the genome of the house fly using DNA from female flies. The sequenced genome is 691 Mb. Compared with Drosophila melanogaster, the genome contains a rich resource of shared and novel protein coding genes, a significantly higher amount of repetitive elements, and substantial increases in copy number and diversity of both the recognition and effector components of the immune system, consistent with life in a pathogen-rich environment. There are 146 P450 genes, plus 11 pseudogenes, in M. domestica, representing a significant increase relative to D. melanogaster and suggesting the presence of enhanced detoxification in house flies. Relative to D. melanogaster, M. domestica has also evolved an expanded repertoire of chemoreceptors and odorant binding proteins, many associated with gustation. CONCLUSIONS: This represents the first genome sequence of an insect that lives in intimate association with abundant animal pathogens. The house fly genome provides a rich resource for enabling work on innovative methods of insect control, for understanding the mechanisms of insecticide resistance, genetic adaptation to high pathogen loads, and for exploring the basic biology of this important pest. The genome of this species will also serve as a close out-group to Drosophila in comparative genomic studies.
ESTHER : Scott_2014_Genome.Biol_15_466
PubMedSearch : Scott_2014_Genome.Biol_15_466
PubMedID: 25315136
Gene_locus related to this paper: musdo-a0a1i8n2v5 , musdo-a0a1i8n5k8

Title : Functional characterisation of a nicotinic acetylcholine receptor alpha subunit from the brown dog tick, Rhipicephalus sanguineus - Lees_2014_Int.J.Parasitol_44_75
Author(s) : Lees K , Jones AK , Matsuda K , Akamatsu M , Sattelle DB , Woods DJ , Bowman AS
Ref : International Journal for Parasitology , 44 :75 , 2014
Abstract : Ticks and tick-borne diseases have a major impact on human and animal health worldwide. Current control strategies rely heavily on the use of chemical acaricides, most of which target the CNS and with increasing resistance, new drugs are urgently needed. Nicotinic acetylcholine receptors (nAChRs) are targets of highly successful insecticides. We isolated a full-length nAChR alpha subunit from a normalised cDNA library from the synganglion (brain) of the brown dog tick, Rhipicephalus sanguineus. Phylogenetic analysis has shown this R. sanguineus nAChR to be most similar to the insect alpha1 nAChR group and has been named Rsanalpha1. Rsanalpha1 is distributed in multiple tick tissues and is present across all life-stages. When expressed in Xenopus laevis oocytes Rsanalpha1 failed to function as a homomer, with and without the addition of either Caenorhabditis elegans resistance-to-cholinesterase (RIC)-3 or X. laevis RIC-3. When co-expressed with chicken beta2 nAChR, Rsanalpha1 evoked concentration-dependent, inward currents in response to acetylcholine (ACh) and showed sensitivity to nicotine (100muM) and choline (100muM). Rsanalpha1/beta2 was insensitive to both imidacloprid (100muM) and spinosad (100muM). The unreliable expression of Rsanalpha1 in vitro suggests that additional subunits or chaperone proteins may be required for more robust expression. This study enhances our understanding of nAChRs in arachnids and may provide a basis for further studies on the interaction of compounds with the tick nAChR as part of a discovery process for novel acaricides.
ESTHER : Lees_2014_Int.J.Parasitol_44_75
PubMedSearch : Lees_2014_Int.J.Parasitol_44_75
PubMedID: 24291321

Title : Xenopus laevis RIC-3 enhances the functional expression of the C. elegans homomeric nicotinic receptor, ACR-16, in Xenopus oocytes - Bennett_2012_J.Neurochem_123_911
Author(s) : Bennett HM , Lees K , Harper KM , Jones AK , Sattelle DB , Wonnacott S , Wolstenholme AJ
Ref : Journal of Neurochemistry , 123 :911 , 2012
Abstract : RIC-3 enhances the functional expression of certain nicotinic acetylcholine receptors (nAChRs) in vertebrates and invertebrates and increases the availability of functional receptors in cultured cells and Xenopus laevis oocytes. Maximal activity of RIC-3 may be cell-type dependent, so neither mammalian nor invertebrate proteins is optimal in amphibian oocytes. We cloned the X. laevis ric-3 cDNA and tested the frog protein in oocyte expression studies. X. laevis RIC-3 shares 52% amino acid identity with human RIC-3 and only 17% with that of Caenorhabditis elegans. We used the C. elegans nicotinic receptor, ACR-16, to compare the ability of RIC-3 from three species to enhance receptor expression. In the absence of RIC-3, the proportion of oocytes expressing detectable nAChRs was greatly reduced. Varying the ratio of acr-16 to X. laevis ric-3 cRNAs injected into oocytes had little impact on the total cell current. When X. laevis, human or C. elegans ric-3 cRNAs were co-injected with acr-16 cRNA (1 : 1 ratio), 100 muM acetylcholine induced larger currents in oocytes expressing X. laevis RIC-3 compared with its orthologues. This provides further evidence for a species-specific component of RIC-3 activity, and suggests that X. laevis RIC-3 is useful for enhancing the expression of invertebrate nAChRs in X. laevis oocytes.
ESTHER : Bennett_2012_J.Neurochem_123_911
PubMedSearch : Bennett_2012_J.Neurochem_123_911
PubMedID: 22970690

Title : Cotinine reduces amyloid-beta aggregation and improves memory in Alzheimer's disease mice - Echeverria_2011_J.Alzheimers.Dis_24_817
Author(s) : Echeverria V , Zeitlin R , Burgess S , Patel S , Barman A , Thakur G , Mamcarz M , Wang L , Sattelle DB , Kirschner DA , Mori T , Leblanc RM , Prabhakar R , Arendash GW
Ref : J Alzheimers Dis , 24 :817 , 2011
Abstract : Alzheimer's disease (AD) affects millions of people world-wide and new effective and safe therapies are needed. Cotinine, the main metabolite of nicotine, has a long half-life and does not have cardiovascular or addictive side effects in humans. We studied the effect of cotinine on amyloid-beta (Abeta) aggregation as well as addressed its impact on working and reference memories. Cotinine reduced Abeta deposition, improved working and reference memories, and inhibited Abeta oligomerization in the brains of transgenic (Tg) 6799 AD mice. In vitro studies confirmed the inhibitory effect of cotinine on Abeta1-42 aggregation. Cotinine stimulated Akt signaling, including the inhibition of glycogen synthase kinase 3beta (GSK3beta), which promotes neuronal survival and the synaptic plasticity processes underlying learning and memory in the hippocampus and cortex of wild type and Tg6799 AD mice. Simulation of the cotinine-Abeta1-42 complex using molecular dynamics showed that cotinine may interact with key histidine residues of Abeta1-42, altering its structure and inhibiting its aggregation. The good safety profile in humans and its beneficial effects suggest that cotinine may be an excellent therapeutic candidate for the treatment of AD.
ESTHER : Echeverria_2011_J.Alzheimers.Dis_24_817
PubMedSearch : Echeverria_2011_J.Alzheimers.Dis_24_817
PubMedID: 21321389

Title : A Cys-loop mutation in the Caenorhabditis elegans nicotinic receptor subunit UNC-63 impairs but does not abolish channel function - Jones_2011_J.Biol.Chem_286_2550
Author(s) : Jones AK , Rayes D , Al-Diwani A , Maynard TP , Jones R , Hernando G , Buckingham SD , Bouzat C , Sattelle DB
Ref : Journal of Biological Chemistry , 286 :2550 , 2011
Abstract : The nematode Caenorhabditis elegans is an established model organism for studying neurobiology. UNC-63 is a C. elegans nicotinic acetylcholine receptor (nAChR) alpha-subunit. It is an essential component of the levamisole-sensitive muscle nAChR (L-nAChR) and therefore plays an important role in cholinergic transmission at the nematode neuromuscular junction. Here, we show that worms with the unc-63(x26) allele, with its alphaC151Y mutation disrupting the Cys-loop, have deficient muscle function reflected by impaired swimming (thrashing). Single-channel recordings from cultured muscle cells from the mutant strain showed a 100-fold reduced frequency of opening events and shorter channel openings of L-nAChRs compared with those of wild-type worms. Anti-UNC-63 antibody staining in both cultured adult muscle and embryonic cells showed that L-nAChRs were expressed at similar levels in the mutant and wild-type cells, suggesting that the functional changes in the receptor, rather than changes in expression, are the predominant effect of the mutation. The kinetic changes mimic those reported in patients with fast-channel congenital myasthenic syndromes. We show that pyridostigmine bromide and 3,4-diaminopyridine, which are drugs used to treat fast-channel congenital myasthenic syndromes, partially rescued the motility defect seen in unc-63(x26). The C. elegans unc-63(x26) mutant may therefore offer a useful model to assist in the development of therapies for syndromes produced by altered function of human nAChRs.
ESTHER : Jones_2011_J.Biol.Chem_286_2550
PubMedSearch : Jones_2011_J.Biol.Chem_286_2550
PubMedID: 20966081

Title : Diversity of insect nicotinic acetylcholine receptor subunits - Jones_2010_Adv.Exp.Med.Biol_683_25
Author(s) : Jones AK , Sattelle DB
Ref : Advances in Experimental Medicine & Biology , 683 :25 , 2010
Abstract : Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that mediate fast synaptic transmission in the insect nervous system and are targets of a major group of insecticides, the neonicotinoids. They consist of five subunits arranged around a central ion channeL Since the subunit composition determines the functional and pharmacological properties of the receptor the presence of nAChR families comprising several subunit-encodinggenes provides a molecular basis for broad functional diversity. Analyses of genome sequences have shown that nAChR gene families remain compact in diverse insect species, when compared to their nematode andvertebrate counterparts. Thus, the fruit fly (Drosophila melanogaster), malaria mosquito (Anopheles gambiae), honey bee (Apis mellifera), silk worm (Bombyx mon) and the red flour beetle (Tribolium castaneum) possess 10-12 nAChR genes while human and the nematode Caenorhabditis elegans have 16 and 29 respectively. Although insect nAChRgene families are amongst the smallest known, receptor diversity can be considerably increased by the posttranscriptional processes alternative splicing and mRNA A-to-I editingwhich can potentially generate protein products which far outnumber the nAChR genes. These two processes can also generate species-specific subunit isoforms. In addition, each insect possesses at least one highly divergent nAChR subunit which may perform species-specific functions. Species-specific subunit diversification may offer promising targets for future rational design of insecticides that target specific pest insects while sparing beneficial species.
ESTHER : Jones_2010_Adv.Exp.Med.Biol_683_25
PubMedSearch : Jones_2010_Adv.Exp.Med.Biol_683_25
PubMedID: 20737786

Title : Alzheimer's disease: insights from Drosophila melanogaster models - Moloney_2010_Trends.Biochem.Sci_35_228
Author(s) : Moloney A , Sattelle DB , Lomas DA , Crowther DC
Ref : Trends in Biochemical Sciences , 35 :228 , 2010
Abstract : The power of fruit fly genetics is being deployed against some of the most intractable and economically significant problems in modern medicine, the neurodegenerative diseases. Fly models of Alzheimer's disease can be exposed to the rich diversity of biological techniques that are available to the community and are providing new insights into disease mechanisms, and assisting in the identification of novel targets for therapy. Similar approaches might also help us to interpret the results of genome-wide association studies of human neurodegenerative diseases by allowing us to triage gene "hits" according to whether a candidate risk factor gene has a modifying effect on the disease phenotypes in fly model systems.
ESTHER : Moloney_2010_Trends.Biochem.Sci_35_228
PubMedSearch : Moloney_2010_Trends.Biochem.Sci_35_228
PubMedID: 20036556

Title : Functional and evolutionary insights from the genomes of three parasitoid Nasonia species - Werren_2010_Science_327_343
Author(s) : Werren JH , Richards S , Desjardins CA , Niehuis O , Gadau J , Colbourne JK , Beukeboom LW , Desplan C , Elsik CG , Grimmelikhuijzen CJ , Kitts P , Lynch JA , Murphy T , Oliveira DC , Smith CD , van de Zande L , Worley KC , Zdobnov EM , Aerts M , Albert S , Anaya VH , Anzola JM , Barchuk AR , Behura SK , Bera AN , Berenbaum MR , Bertossa RC , Bitondi MM , Bordenstein SR , Bork P , Bornberg-Bauer E , Brunain M , Cazzamali G , Chaboub L , Chacko J , Chavez D , Childers CP , Choi JH , Clark ME , Claudianos C , Clinton RA , Cree AG , Cristino AS , Dang PM , Darby AC , de Graaf DC , Devreese B , Dinh HH , Edwards R , Elango N , Elhaik E , Ermolaeva O , Evans JD , Foret S , Fowler GR , Gerlach D , Gibson JD , Gilbert DG , Graur D , Grunder S , Hagen DE , Han Y , Hauser F , Hultmark D , Hunter HCt , Hurst GD , Jhangian SN , Jiang H , Johnson RM , Jones AK , Junier T , Kadowaki T , Kamping A , Kapustin Y , Kechavarzi B , Kim J , Kiryutin B , Koevoets T , Kovar CL , Kriventseva EV , Kucharski R , Lee H , Lee SL , Lees K , Lewis LR , Loehlin DW , Logsdon JM, Jr. , Lopez JA , Lozado RJ , Maglott D , Maleszka R , Mayampurath A , Mazur DJ , McClure MA , Moore AD , Morgan MB , Muller J , Munoz-Torres MC , Muzny DM , Nazareth LV , Neupert S , Nguyen NB , Nunes FM , Oakeshott JG , Okwuonu GO , Pannebakker BA , Pejaver VR , Peng Z , Pratt SC , Predel R , Pu LL , Ranson H , Raychoudhury R , Rechtsteiner A , Reese JT , Reid JG , Riddle M , Robertson HM , Romero-Severson J , Rosenberg M , Sackton TB , Sattelle DB , Schluns H , Schmitt T , Schneider M , Schuler A , Schurko AM , Shuker DM , Simoes ZL , Sinha S , Smith Z , Solovyev V , Souvorov A , Springauf A , Stafflinger E , Stage DE , Stanke M , Tanaka Y , Telschow A , Trent C , Vattathil S , Verhulst EC , Viljakainen L , Wanner KW , Waterhouse RM , Whitfield JB , Wilkes TE , Williamson MS , Willis JH , Wolschin F , Wyder S , Yamada T , Yi SV , Zecher CN , Zhang L , Gibbs RA , Williamson M
Ref : Science , 327 :343 , 2010
Abstract : We report here genome sequences and comparative analyses of three closely related parasitoid wasps: Nasonia vitripennis, N. giraulti, and N. longicornis. Parasitoids are important regulators of arthropod populations, including major agricultural pests and disease vectors, and Nasonia is an emerging genetic model, particularly for evolutionary and developmental genetics. Key findings include the identification of a functional DNA methylation tool kit; hymenopteran-specific genes including diverse venoms; lateral gene transfers among Pox viruses, Wolbachia, and Nasonia; and the rapid evolution of genes involved in nuclear-mitochondrial interactions that are implicated in speciation. Newly developed genome resources advance Nasonia for genetic research, accelerate mapping and cloning of quantitative trait loci, and will ultimately provide tools and knowledge for further increasing the utility of parasitoids as pest insect-control agents.
ESTHER : Werren_2010_Science_327_343
PubMedSearch : Werren_2010_Science_327_343
PubMedID: 20075255
Gene_locus related to this paper: nasvi-ACHE1 , nasvi-ACHE2 , nasvi-k7in31 , nasvi-k7iwl9 , nasvi-k7iyk8 , nasvi-k7jlv1 , nasvi-k7in32 , nasvi-k7ind2 , nasvi-k7inh0 , nasvi-k7inh1 , nasvi-k7inh2 , nasvi-k7inp9 , nasvi-k7iun7 , nasvi-k7iv21 , nasvi-k7ivn5 , nasvi-k7ivn6 , nasvi-k7iw29 , nasvi-k7iwk5 , nasvi-k7iwl8 , nasvi-k7iz24 , nasvi-k7izb4 , nasvi-k7j5u6 , nasvi-k7j6y1 , nasvi-k7j6y2 , nasvi-k7j6y4 , nasvi-k7j718 , nasvi-k7j755 , nasvi-k7j756 , nasvi-k7j757 , nasvi-k7j7k5 , nasvi-k7j7n7 , nasvi-k7j7r8 , nasvi-k7j7s8 , nasvi-k7j7s9 , nasvi-k7j811 , nasvi-k7iny8 , nasvi-k7izf2 , nasvi-k7iwe2 , nasvi-k7j6w4 , nasvi-k7izl9 , nasvi-k7jf39 , nasvi-k7izl8 , nasvi-k7irf1 , nasvi-k7j7l1

Title : Identification of ion channel genes in the Acyrthosiphon pisum genome - Dale_2010_Insect.Mol.Biol_19 Suppl 2_141
Author(s) : Dale RP , Jones AK , Tamborindeguy C , Davies TG , Amey JS , Williamson S , Wolstenholme A , Field LM , Williamson MS , Walsh TK , Sattelle DB
Ref : Insect Molecular Biology , 19 Suppl 2 :141 , 2010
Abstract : Aphids are major pests of crops, causing hundreds of millions of dollars worth of damage annually. Ion channel proteins are often the targets of modern insecticides and mutations in ion channel genes can lead to resistance to many leading classes of insecticides. The sequencing of the pea aphid, Acyrthosiphon pisum, genome has now allowed detailed in silico analysis of the aphid ion channels. The study has revealed significant differences in the composition of the ion channel families between the aphid and other insects. For example A. pisum does not appear to contain a homologue of the nACh receptor alpha 5 gene whilst the calcium channel beta subunit has been duplicated. These variations could result in differences in function or sensitivity to insecticides. The genome sequence will allow the study of aphid ion channels to be accelerated, leading to a better understanding of the function of these economically important channels. The potential for identifying novel insecticide targets within the aphid is now a step closer.
ESTHER : Dale_2010_Insect.Mol.Biol_19 Suppl 2_141
PubMedSearch : Dale_2010_Insect.Mol.Biol_19 Suppl 2_141
PubMedID: 20482646

Title : The cys-loop ligand-gated ion channel gene superfamily of the parasitoid wasp, Nasonia vitripennis - Jones_2010_Heredity.(Edinb)_104_247
Author(s) : Jones AK , Bera AN , Lees K , Sattelle DB
Ref : Heredity (Edinb) , 104 :247 , 2010
Abstract : Members of the cys-loop ligand-gated ion channel (cysLGIC) superfamily mediate chemical neurotransmission and are studied extensively as potential targets of drugs used to treat neurological disorders, such as Alzheimer's disease. Insect cys-loop LGICs also have central roles in the nervous system and are targets of highly successful insecticides. Here, we describe the cysLGIC superfamily of the parasitoid wasp, Nasonia vitripennis, which is emerging as a highly useful model organism and is deployed as a biological control of insect pests. The wasp superfamily consists of 26 genes, which is the largest insect cysLGIC superfamily characterized, whereas Drosophila melanogaster, Apis mellifera and Tribolium castaneum have 23, 21 and 24, respectively. As with Apis, Drosophila and Tribolium, Nasonia possesses ion channels predicted to be gated by acetylcholine, gamma-amino butyric acid, glutamate and histamine, as well as orthologues of the Drosophila pH-sensitive chloride channel (pHCl), CG8916 and CG12344. Similar to other insects, wasp cysLGIC diversity is broadened by alternative splicing and RNA A-to-I editing, which may also serve to generate species-specific receptor isoforms. These findings on N. vitripennis enhance our understanding of cysLGIC functional genomics and provide a useful basis for the study of their function in the wasp model, as well as for the development of improved insecticides that spare a major beneficial insect species.
ESTHER : Jones_2010_Heredity.(Edinb)_104_247
PubMedSearch : Jones_2010_Heredity.(Edinb)_104_247
PubMedID: 20087392

Title : Proteins interacting with nicotinic acetylcholine receptors: expanding functional and therapeutic horizons - Jones_2010_Trends.Pharmacol.Sci_31_455
Author(s) : Jones AK , Buckingham SD , Sattelle DB
Ref : Trends in Pharmacological Sciences , 31 :455 , 2010
Abstract : Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that carry out the fast actions of the neurotransmitter acetylcholine (ACh). Over the past 30 years, it has become clear that the activity of nAChRs is dependent on their interaction with a host of proteins, and the number of these that have been identified has increased considerably with recent large-scale proteomic analyses. This review focuses on these interacting proteins, discussing how they regulate a wide range of functions including receptor assembly, and trafficking to and from the cell surface, as well as how they directly modulate functional characteristics such as sensitivity and the degree of response to ACh. Mutations giving rise to disease states highlight the importance of these interacting proteins. Here, we consider their potential as future therapeutic targets for treating diseases associated with altered nAChR function.
ESTHER : Jones_2010_Trends.Pharmacol.Sci_31_455
PubMedSearch : Jones_2010_Trends.Pharmacol.Sci_31_455
PubMedID: 20674046

Title : Diverse actions and target-site selectivity of neonicotinoids: structural insights - Matsuda_2009_Mol.Pharmacol_76_1
Author(s) : Matsuda K , Kanaoka S , Akamatsu M , Sattelle DB
Ref : Molecular Pharmacology , 76 :1 , 2009
Abstract : The nicotinic acetylcholine receptors (nAChRs) are targets for human and veterinary medicines as well as insecticides. Subtype-selectivity among the diverse nAChR family members is important for medicines targeting particular disorders, and pest-insect selectivity is essential for the development of safer, environmentally acceptable insecticides. Neonicotinoid insecticides selectively targeting insect nAChRs have important applications in crop protection and animal health. Members of this class exhibit strikingly diverse actions on their nAChR targets. Here we review the chemistry and diverse actions of neonicotinoids on insect and mammalian nAChRs. Electrophysiological studies on native nAChRs and on wild-type and mutagenized recombinant nAChRs have shown that basic residues particular to loop D of insect nAChRs are likely to interact electrostatically with the nitro group of neonicotinoids. In 2008, the crystal structures were published showing neonicotinoids docking into the acetylcholine binding site of molluscan acetylcholine binding proteins with homology to the ligand binding domain (LBD) of nAChRs. The crystal structures showed that 1) glutamine in loop D, corresponding to the basic residues of insect nAChRs, hydrogen bonds with the NO(2) group of imidacloprid and 2) neonicotinoid-unique stacking and CH-pi bonds at the LBD. A neonicotinoid-resistant strain obtained by laboratory-screening has been found to result from target site mutations, and possible reasons for this are also suggested by the crystal structures. The prospects of designing neonicotinoids that are safe not only for mammals but also for beneficial insects such as honey bees (Apis mellifera) are discussed in terms of interactions with non-alpha nAChR subunits.
ESTHER : Matsuda_2009_Mol.Pharmacol_76_1
PubMedSearch : Matsuda_2009_Mol.Pharmacol_76_1
PubMedID: 19321668

Title : Combined roles of loops C and D in the interactions of a neonicotinoid insecticide imidacloprid with the alpha4beta2 nicotinic acetylcholine receptor - Toshima_2009_Neuropharmacol_56_264
Author(s) : Toshima K , Kanaoka S , Yamada A , Tarumoto K , Akamatsu M , Sattelle DB , Matsuda K
Ref : Neuropharmacology , 56 :264 , 2009
Abstract : Neonicotinoid insecticides are widely used for crop protection based on their selective actions on insect nicotinic acetylcholine receptors (insect nAChRs). Loops C and D in insect nAChRs have been shown to possess structural features favorable for neonicotinoid-nAChR interactions. However, it remains to be resolved whether such features serve either co-operatively, or independently, to enhance neonicotinoid sensitivity of nAChRs. We therefore examined using voltage-clamp electrophysiology the effects on the response to imidacloprid of combinatorial substitutions of residues in loops C and D of the chicken alpha4beta2 nAChR by those present in insect nAChRs. The E219P mutation in loop C of the alpha4 subunit resulted in enhanced responses to imidacloprid of alpha4beta2, whereas E219S and E219T mutations barely influenced its actions. On the other hand, mutations in loop D (T77R; E79V and T77N; E79R) alone shifted the imidacloprid concentration-response curve to the left (lower concentrations). Interestingly, all three mutations did, however, further enhance the agonist efficacy of imidacloprid when combined with the mutations in loop D. Such synergistic effects of the two loops on the interactions with imidaclprid were observed irrespective of subunit stoichiometry. Computational modeling of the ligand binding domain of the wild-type and mutant alpha4beta2 nAChRs using the crystal structure of the acetylcholine binding protein from Lymnaea stagnalis also indicated that interactions with loop F of loops C and D may contribute to determining the response to imidacloprid.
ESTHER : Toshima_2009_Neuropharmacol_56_264
PubMedSearch : Toshima_2009_Neuropharmacol_56_264
PubMedID: 18790701

Title : Invertebrate nicotinic acetylcholine receptors - Sattelle_2009_J.Pestic.Sci_34_233
Author(s) : Sattelle DB
Ref : Journal of Pesticide Science , 34 :233 , 2009
Abstract : The sequencing of several nematode and insect genomes has accelerated our understanding of the molecular and functional diversity of gene family members and their functional roles. The nicotinic acetylcholine receptor (nAChR) gene families, members of which mediate fast synaptic transmission and serve as targets for human and anthelmintic drugs as well as insecticides, are of considerable interest. Genomes of the free-living nematode and genetic model organism, Caenorhabditis elegans as well as the parasitic nematode Brugia malayii have been sequenced. Following the sequencing of the genome of the fruitfly Drosophila melanogaster, genomes are now available for the malarial vector Anopheles gambiae, the stored agricultural products pest Tribolium castaneum, a species of considerable agricultural benefit, the honeybee Apis mellifera, and other insects. Some nematode nAChR families are among the largest nAChR families known with many subunit isoforms, whereas insect nAChR families are often more compact. However, alternative splicing and RNA editing can ensure an equally rich molecular diversity of insect nAChRs. Subunits making up the L-type nematode levamisole-sensitive nAChR and the N-type nicotine-sensitive nAChR have now been identified and functionally expressed. Imidacloprid-sensitive nAChRs have also been expressed using hybrid receptors containing insect subunits. Such studies are enhancing the prospects of receptor target-based screening for new animal health drugs and agricultural products.
ESTHER : Sattelle_2009_J.Pestic.Sci_34_233
PubMedSearch : Sattelle_2009_J.Pestic.Sci_34_233

Title : Poster: The nicotinic acetylcholine receptors of Ascaris suum -
Author(s) : Bennett HM , Williamson SM , McCavera S , Robertson AP , Martin RJ , Williams T , Woods DJ , Sattelle DB , Wolstenholme AJ
Ref : Biochemical Pharmacology , 78 :899 , 2009

Title : Nicotinic acetylcholine receptor signalling: roles in Alzheimer's disease and amyloid neuroprotection - Buckingham_2009_Pharmacol.Rev_61_39
Author(s) : Buckingham SD , Jones AK , Brown LA , Sattelle DB
Ref : Pharmacol Rev , 61 :39 , 2009
Abstract : Alzheimer's disease (AD), the major contributor to dementia in the elderly, involves accumulation in the brain of extracellular plaques containing the beta-amyloid protein (Abeta) and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. AD is also characterized by a loss of neurons, particularly those expressing nicotinic acetylcholine receptors (nAChRs), thereby leading to a reduction in nAChR numbers. The Abeta(1-42) protein, which is toxic to neurons, is critical to the onset and progression of AD. The discovery of new drug therapies for AD is likely to be accelerated by an improved understanding of the mechanisms whereby Abeta causes neuronal death. We examine the evidence for a role in Abeta(1-42) toxicity of nAChRs; paradoxically, nAChRs can also protect neurons when activated by nicotinic ligands. Abeta peptides and nicotine differentially activate several intracellular signaling pathways, including the phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene homolog pathway, the extracellular signal-regulated kinase/mitogen-activated protein kinase, and JAK-2/STAT-3 pathways. These pathways control cell death or survival and the secretion of Abeta peptides. We propose that understanding the differential activation of these pathways by nicotine and/or Abeta(1-42) may offer the prospect of new routes to therapy for AD.
ESTHER : Buckingham_2009_Pharmacol.Rev_61_39
PubMedSearch : Buckingham_2009_Pharmacol.Rev_61_39
PubMedID: 19293145

Title : The nicotinic acetylcholine receptors of the parasitic nematode Ascaris suum: formation of two distinct drug targets by varying the relative expression levels of two subunits - Williamson_2009_PLoS.Pathog_5_e1000517
Author(s) : Williamson SM , Robertson AP , Brown L , Williams T , Woods DJ , Martin RJ , Sattelle DB , Wolstenholme AJ
Ref : PLoS Pathog , 5 :e1000517 , 2009
Abstract : Parasitic nematodes are of medical and veterinary importance, adversely affecting human health and animal welfare. Ascaris suum is a gastrointestinal parasite of pigs; in addition to its veterinary significance it is a good model of the human parasite Ascaris lumbricoides, estimated to infect approximately 1.4 billion people globally. Anthelmintic drugs are essential to control nematode parasites, and nicotinic acetylcholine receptors (nAChRs) on nerve and muscle are the targets of cholinergic anthelmintics such as levamisole and pyrantel. Previous genetic analyses of nematode nAChRs have been confined to Caenorhabditis elegans, which is phylogenetically distinct from Ascaris spp. and many other important parasites. Here we report the cloning and expression of two nAChR subunit cDNAs from A. suum. The subunits are very similar in sequence to C. elegans UNC-29 and UNC-38, are expressed on muscle cells and can be expressed robustly in Xenopus oocytes to form acetylcholine-, nicotine-, levamisole- and pyrantel-sensitive channels. We also demonstrate that changing the stoichiometry of the receptor by injecting different ratios of the subunit cRNAs can reproduce two of the three pharmacological subtypes of nAChR present in A. suum muscle cells. When the ratio was 5:1 (Asu-unc-38ratioAsu-unc-29), nicotine was a full agonist and levamisole was a partial agonist, and oocytes responded to oxantel, but not pyrantel. At the reverse ratio (1:5 Asu-unc-38ratioAsu-unc-29), levamisole was a full agonist and nicotine was a partial agonist, and the oocytes responded to pyrantel, but not oxantel. These results represent the first in vitro expression of any parasitic nicotinic receptor and show that their properties are substantially different from those of C. elegans. The results also show that changing the expression level of a single receptor subunit dramatically altered the efficacy of some anthelmintic drugs. In vitro expression of these subunits may permit the development of parasite-specific screens for future anthelmintics.
ESTHER : Williamson_2009_PLoS.Pathog_5_e1000517
PubMedSearch : Williamson_2009_PLoS.Pathog_5_e1000517
PubMedID: 19609360

Title : Comparative pharmacology and computational modelling yield insights into allosteric modulation of human alpha7 nicotinic acetylcholine receptors - Sattelle_2009_Biochem.Pharmacol_78(7)_836
Author(s) : Sattelle DB , Buckingham SD , Akamatsu M , Matsuda K , Pienaar IS , Jones AK , Sattelle BM , Almond A , Blundell CD
Ref : Biochemical Pharmacology , 78 :836 , 2009
Abstract : The human alpha7 nicotinic acetylcholine receptor (nAChR) subunit and its Caenorhabditis elegans homolog, ACR-16, can generate functional recombinant homomeric receptors when expressed in Xenopus laevis oocytes. Both nAChRs express robustly in the presence of the co-injected chaperone, RIC-3, and show striking differences in the actions of a type I positive allosteric modulator (PAM), ivermectin (IVM). Type I PAMs are characterised by an increase in amplitude only of the response to acetylcholine (ACh), whereas type II PAMs exhibit, in addition, changes in time-course/desensitization of the ACh response. The type I PAMs, ivermectin, 5-hydroxyindole (5-HI), NS-1738 and genistein and the type II PAM, PNU-120596, are all active on human alpha7 but are without PAM activity on ACR-16, where they attenuate the amplitude of the ACh response. We used the published structure of avermectin B1a to generate a model of IVM, which was then docked into the candidate transmembrane allosteric binding site on alpha7 and ACR-16 in an attempt to gain insights into the observed differences in IVM actions. The new pharmacological findings and computational approaches being developed may inform the design of novel PAM drugs targeting major neurological disorders.
ESTHER : Sattelle_2009_Biochem.Pharmacol_78(7)_836
PubMedSearch : Sattelle_2009_Biochem.Pharmacol_78(7)_836
PubMedID: 19549506

Title : Alternative splicing of the Anopheles gambiae nicotinic acetylcholine receptor, Agamalphabeta9, generates both alpha and beta subunits - Jones_2009_Invert.Neurosci_9_77
Author(s) : Jones AK , Buckingham SD , Brown LA , Sattelle DB
Ref : Invert Neurosci , 9 :77 , 2009
Abstract : Nicotinic acetylcholine receptors (nAChRs) are the members of the cys-loop ligand-gated ion channel superfamily and are formed by five subunits arranged around a central ion channel. Each subunit is encoded by a separate gene and is classified as either alpha or non-alpha depending on the presence or absence, respectively, of two adjacent cysteine residues which are important for acetylcholine binding. Here, we report for the first time a single nAChR gene encoding both alpha and non-alpha subunits. Specifically, alternative splicing of the Anopheles gambiae nAChR subunit, previously called Agamalpha9 and renamed here Agamalphabeta9, generates two variants, one possessing the two cysteines (denoted Agamalphabeta9(alpha)) and the other lacking the cysteine doublet (Agamalphabeta9(beta)). Attempts to heterologously express functional nAChRs consisting of the Agamalphabeta9 splice variants in Xenopus laevis oocytes were unsuccessful. Our findings further characterise a potential target to control the malaria mosquito as well as provide insights into the diversification of nAChRs.
ESTHER : Jones_2009_Invert.Neurosci_9_77
PubMedSearch : Jones_2009_Invert.Neurosci_9_77
PubMedID: 19669815

Title : The cys-loop ligand-gated ion channel gene superfamily of the nematode, Caenorhabditis elegans - Jones_2008_Invert.Neurosci_8_41
Author(s) : Jones AK , Sattelle DB
Ref : Invert Neurosci , 8 :41 , 2008
Abstract : The nematode, Caenorhabditis elegans, possesses the most extensive known superfamily of cys-loop ligand-gated ion channels (cys-loop LGICs) consisting of 102 subunit-encoding genes. Less than half of these genes have been functionally characterised which include cation-permeable channels gated by acetylcholine (ACh) and gamma-aminobutyric acid (GABA) as well as anion-selective channels gated by ACh, GABA, glutamate and serotonin. Following the guidelines set for genetic nomenclature for C. elegans, we have designated unnamed subunits as lgc genes (ligand-gated ion channels of the cys-loop superfamily). Phylogenetic analysis shows that several of these lgc subunits form distinct groups which may represent novel cys-loop LGIC subtypes.
ESTHER : Jones_2008_Invert.Neurosci_8_41
PubMedSearch : Jones_2008_Invert.Neurosci_8_41
PubMedID: 18288508

Title : The genome of the model beetle and pest Tribolium castaneum - Richards_2008_Nature_452_949
Author(s) : Richards S , Gibbs RA , Weinstock GM , Brown SJ , Denell R , Beeman RW , Gibbs R , Bucher G , Friedrich M , Grimmelikhuijzen CJ , Klingler M , Lorenzen M , Roth S , Schroder R , Tautz D , Zdobnov EM , Muzny D , Attaway T , Bell S , Buhay CJ , Chandrabose MN , Chavez D , Clerk-Blankenburg KP , Cree A , Dao M , Davis C , Chacko J , Dinh H , Dugan-Rocha S , Fowler G , Garner TT , Garnes J , Gnirke A , Hawes A , Hernandez J , Hines S , Holder M , Hume J , Jhangiani SN , Joshi V , Khan ZM , Jackson L , Kovar C , Kowis A , Lee S , Lewis LR , Margolis J , Morgan M , Nazareth LV , Nguyen N , Okwuonu G , Parker D , Ruiz SJ , Santibanez J , Savard J , Scherer SE , Schneider B , Sodergren E , Vattahil S , Villasana D , White CS , Wright R , Park Y , Lord J , Oppert B , Brown S , Wang L , Weinstock G , Liu Y , Worley K , Elsik CG , Reese JT , Elhaik E , Landan G , Graur D , Arensburger P , Atkinson P , Beidler J , Demuth JP , Drury DW , Du YZ , Fujiwara H , Maselli V , Osanai M , Robertson HM , Tu Z , Wang JJ , Wang S , Song H , Zhang L , Werner D , Stanke M , Morgenstern B , Solovyev V , Kosarev P , Brown G , Chen HC , Ermolaeva O , Hlavina W , Kapustin Y , Kiryutin B , Kitts P , Maglott D , Pruitt K , Sapojnikov V , Souvorov A , Mackey AJ , Waterhouse RM , Wyder S , Kriventseva EV , Kadowaki T , Bork P , Aranda M , Bao R , Beermann A , Berns N , Bolognesi R , Bonneton F , Bopp D , Butts T , Chaumot A , Denell RE , Ferrier DE , Gordon CM , Jindra M , Lan Q , Lattorff HM , Laudet V , von Levetsow C , Liu Z , Lutz R , Lynch JA , da Fonseca RN , Posnien N , Reuter R , Schinko JB , Schmitt C , Schoppmeier M , Shippy TD , Simonnet F , Marques-Souza H , Tomoyasu Y , Trauner J , Van der Zee M , Vervoort M , Wittkopp N , Wimmer EA , Yang X , Jones AK , Sattelle DB , Ebert PR , Nelson D , Scott JG , Muthukrishnan S , Kramer KJ , Arakane Y , Zhu Q , Hogenkamp D , Dixit R , Jiang H , Zou Z , Marshall J , Elpidina E , Vinokurov K , Oppert C , Evans J , Lu Z , Zhao P , Sumathipala N , Altincicek B , Vilcinskas A , Williams M , Hultmark D , Hetru C , Hauser F , Cazzamali G , Williamson M , Li B , Tanaka Y , Predel R , Neupert S , Schachtner J , Verleyen P , Raible F , Walden KK , Angeli S , Foret S , Schuetz S , Maleszka R , Miller SC , Grossmann D
Ref : Nature , 452 :949 , 2008
Abstract : Tribolium castaneum is a member of the most species-rich eukaryotic order, a powerful model organism for the study of generalized insect development, and an important pest of stored agricultural products. We describe its genome sequence here. This omnivorous beetle has evolved the ability to interact with a diverse chemical environment, as shown by large expansions in odorant and gustatory receptors, as well as P450 and other detoxification enzymes. Development in Tribolium is more representative of other insects than is Drosophila, a fact reflected in gene content and function. For example, Tribolium has retained more ancestral genes involved in cell-cell communication than Drosophila, some being expressed in the growth zone crucial for axial elongation in short-germ development. Systemic RNA interference in T. castaneum functions differently from that in Caenorhabditis elegans, but nevertheless offers similar power for the elucidation of gene function and identification of targets for selective insect control.
ESTHER : Richards_2008_Nature_452_949
PubMedSearch : Richards_2008_Nature_452_949
PubMedID: 18362917
Gene_locus related to this paper: trica-ACHE1 , trica-ACHE2 , trica-d2a0g9 , trica-d2a0h0 , trica-d2a0w9 , trica-d2a0x0 , trica-d2a0x1 , trica-d2a0x3 , trica-d2a0x4.1 , trica-d2a0x4.2 , trica-d2a0x6 , trica-d2a2b8 , trica-d2a2h1 , trica-d2a3c3 , trica-d2a3g9 , trica-d2a5y5 , trica-d2a309 , trica-d2a514 , trica-d2a515 , trica-d2a516 , trica-d2a577 , trica-d2a578 , trica-d6w6x8 , trica-d6w7f9 , trica-d6w7h2 , trica-d6w8e7 , trica-d6w9c0 , trica-d6w855 , trica-d6wac8 , trica-d6wan4 , trica-d6wd50 , trica-d6wd73 , trica-d6wd74 , trica-A0A139WM97 , trica-d6wfu3 , trica-d6wgl2 , trica-d6wj57 , trica-d6wj59 , trica-d6wjs3 , trica-d6wl31 , trica-d6wnv1 , trica-d6wpl0 , trica-d6wqd6 , trica-d6wqr4 , trica-d6ws52 , trica-d6wsm0 , trica-d6wu38 , trica-d6wu39 , trica-d6wu40 , trica-d6wu41 , trica-d6wu44 , trica-d6wvk5 , trica-d6wvz7 , trica-d6wwu9 , trica-d6wwv0 , trica-d6wxz0 , trica-d6wyy1 , trica-d6wyy2 , trica-d6x0z2 , trica-d6x0z5 , trica-d6x0z6 , trica-d6x4b2 , trica-d6x4e8 , trica-d6x4e9 , trica-d6x197 , trica-d7eip7 , trica-d7eld3 , trica-d7us45 , trica-q5wm43 , trica-q5zex9 , trica-d6wie5 , trica-d6w7t0 , trica-d6x4h0 , trica-d6x4h1 , trica-a0a139wae8 , trica-a0a139wc96 , trica-d6x325 , trica-d2a4s2 , trica-d6wvw8

Title : Amyloid peptides and ion channel function in Drosophila models of Alzheimer's disease -
Author(s) : Brown LA , Mee CJ , Kidd JF , Sattelle DB
Ref : SEB Exp Biol Ser , 60 :79 , 2008
PubMedID: 18309788

Title : Crystal structures of Lymnaea stagnalis AChBP in complex with neonicotinoid insecticides imidacloprid and clothianidin - Ihara_2008_Invert.Neurosci_8_71
Author(s) : Ihara M , Okajima T , Yamashita A , Oda T , Hirata K , Nishiwaki H , Morimoto T , Akamatsu M , Ashikawa Y , Kuroda S , Mega R , Kuramitsu S , Sattelle DB , Matsuda K
Ref : Invert Neurosci , 8 :71 , 2008
Abstract : Neonicotinoid insecticides, which act on nicotinic acetylcholine receptors (nAChRs) in a variety of ways, have extremely low mammalian toxicity, yet the molecular basis of such actions is poorly understood. To elucidate the molecular basis for nAChR-neonicotinoid interactions, a surrogate protein, acetylcholine binding protein from Lymnaea stagnalis (Ls-AChBP) was crystallized in complex with neonicotinoid insecticides imidacloprid (IMI) or clothianidin (CTD). The crystal structures suggested that the guanidine moiety of IMI and CTD stacks with Tyr185, while the nitro group of IMI but not of CTD makes a hydrogen bond with Gln55. IMI showed higher binding affinity for Ls-AChBP than that of CTD, consistent with weaker CH-pi interactions in the Ls-AChBP-CTD complex than in the Ls-AChBP-IMI complex and the lack of the nitro group-Gln55 hydrogen bond in CTD. Yet, the NH at position 1 of CTD makes a hydrogen bond with the backbone carbonyl of Trp143, offering an explanation for the diverse actions of neonicotinoids on nAChRs.
ESTHER : Ihara_2008_Invert.Neurosci_8_71
PubMedSearch : Ihara_2008_Invert.Neurosci_8_71
PubMedID: 18338186

Title : A role for Leu118 of loop E in agonist binding to the alpha 7 nicotinic acetylcholine receptor - Amiri_2008_Mol.Pharmacol_73_1659
Author(s) : Amiri S , Shimomura M , Vijayan R , Nishiwaki H , Akamatsu M , Matsuda K , Jones AK , Sansom MS , Biggin PC , Sattelle DB
Ref : Molecular Pharmacology , 73 :1659 , 2008
Abstract : Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels mediating fast cholinergic synaptic transmission in the brain and at neuromuscular junctions. We used the structure of the acetylcholine binding protein from Lymnaea stagnalis to model the chicken alpha7 agonist-binding domain. The initial models and a preliminary docking study suggested that position Leu118 may play an important role in determining agonist actions on alpha7. A prediction from these in silico studies, that L118E and L118D would retain binding to acetylcholine but L118K and L118R would not, was confirmed in electrophysiological studies on functional recombinant mutant receptors expressed in Xenopus laevis oocytes. The functional studies also demonstrated that residues at position 118 have a dramatic effect on the actions of imidacloprid (a partial agonist of wild-type alpha7 receptors) and its des-nitro derivative. Molecular dynamics simulations confirmed that Leu118 can strongly influence agonist binding and that the model was robust in terms of its prediction for acetylcholine binding. Together, the results indicate a role for Leu118 in influencing agonist actions on alpha7 nAChRs.
ESTHER : Amiri_2008_Mol.Pharmacol_73_1659
PubMedSearch : Amiri_2008_Mol.Pharmacol_73_1659
PubMedID: 18339894

Title : The cys-loop ligand-gated ion channel gene superfamily of the red flour beetle, Tribolium castaneum - Jones_2007_BMC.Genomics_8_327
Author(s) : Jones AK , Sattelle DB
Ref : BMC Genomics , 8 :327 , 2007
Abstract : BACKGROUND: Members of the cys-loop ligand-gated ion channel (cys-loop LGIC) superfamily mediate chemical neurotransmission and are studied extensively as potential targets of drugs used to treat neurological disorders such as Alzheimer's disease. Insect cys-loop LGICs are also of interest as they are targets of highly successful insecticides. The red flour beetle, Tribolium castaneum, is a major pest of stored agricultural products and is also an important model organism for studying development.
RESULTS: As part of the T. castaneum genome sequencing effort, we have characterized the beetle cys-loop LGIC superfamily which is the third insect superfamily to be described after those of Drosophila melanogaster and Apis mellifera, and also the largest consisting of 24 genes. As with Drosophila and Apis, Tribolium possesses ion channels gated by acetylcholine, gamma-amino butyric acid (GABA), glutamate and histamine as well as orthologs of the Drosophila pH-sensitive chloride channel subunit (pHCl), CG8916 and CG12344. Similar to Drosophila and Apis, Tribolium cys-loop LGIC diversity is broadened by alternative splicing although the beetle orthologs of RDL and GluCl possess more variants of exon 3. Also, RNA A-to-I editing was observed in two Tribolium nicotinic acetylcholine receptor subunits, Tcasalpha6 and Tcasbeta1. Editing in Tcasalpha6 is evolutionarily conserved with D. melanogaster, A. mellifera and Heliothis virescens, whereas Tcasbeta1 is edited at a site so far only observed in the beetle. CONCLUSION: Our findings reveal that in diverse insect species the cys-loop LGIC superfamily has remained compact with only minor changes in gene numbers. However, alternative splicing, RNA editing and the presence of divergent subunits broadens the cys-loop LGIC proteome and generates species-specific receptor isoforms. These findings on Tribolium castaneum enhance our understanding of cys-loop LGIC functional genomics and provide a useful basis for the development of improved insecticides that target an important agricultural pest.
ESTHER : Jones_2007_BMC.Genomics_8_327
PubMedSearch : Jones_2007_BMC.Genomics_8_327
PubMedID: 17880682

Title : Exploring the pharmacological properties of insect nicotinic acetylcholine receptors - Thany_2007_Trends.Pharmacol.Sci_28_14
Author(s) : Thany SH , Lenaers G , Raymond-Delpech V , Sattelle DB , Lapied B
Ref : Trends in Pharmacological Sciences , 28 :14 , 2007
Abstract : Insect nicotinic acetylcholine (nACh) receptors are molecular targets of insecticides such as neonicotinoids that are used to control disease-carrying insects and agricultural pests. To date, several insect nACh receptor subunits have been identified, indicating different nACh receptor subtypes and pharmacological profiles. Because of the difficulty in expressing functional insect nACh receptors in heterologous systems, new research tools are needed. Studies on insects resistant to the insecticide imidacloprid and on laboratory-generated hybrid and chimaeric nACh receptors in vitro have provided information about the molecular basis of receptor diversity, neonicotinoid resistance and selectivity. Additionally, recent results indicate that the sensitivity of insect nACh receptors to imidacloprid can be modulated by intracellular phosphorylation mechanisms, which offers a new approach to studying insect nACh receptor pharmacology.
ESTHER : Thany_2007_Trends.Pharmacol.Sci_28_14
PubMedSearch : Thany_2007_Trends.Pharmacol.Sci_28_14
PubMedID: 17156860

Title : Molecular pharmacology of insect ion channels and implications for insect toxicology -
Author(s) : Matsuda K , Ozoe Y , Sattelle DB
Ref : Invert Neurosci , 7 :1 , 2007
PubMedID: 17333310

Title : Nicotinic acetylcholine receptors as drug\/chemical targets, contributions from comparative genomics, forward and reverse genetics -
Author(s) : Sattelle DB , Jones AK , Brown LA , Buckingham SD , Mee CJ , Pym L
Ref : SEB Exp Biol Ser , 58 :93 , 2007
PubMedID: 17608238

Title : Actions of snake neurotoxins on an insect nicotinic cholinergic synapse - Hue_2007_Invert.Neurosci_7_173
Author(s) : Hue B , Buckingham SD , Buckingham D , Sattelle DB
Ref : Invert Neurosci , 7 :173 , 2007
Abstract : Here we examine the actions of six snake neurotoxins (alpha-cobratoxin from Naja naja siamensis, erabutoxin-a and b from Laticauda semifasciata; CM12 from N. haje annulifera, toxin III 4 from Notechis scutatus and a long toxin from N. haje) on nicotinic acetylcholine receptors in the cercal afferent, giant interneuron 2 synapse of the cockroach, Periplaneta americana. All toxins tested reduced responses to directly-applied ACh as well as EPSPs evoked by electrical stimulation of nerve XI with similar time courses, suggesting that their action is postsynaptic. Thus, these nicotinic receptors in a well-characterized insect synapse are sensitive to both long and short chain neurotoxins. This considerably expands the range of snake toxins that block insect nicotinic acetylcholine receptors and may enable further pharmacological distinctions between nAChR subtypes.
ESTHER : Hue_2007_Invert.Neurosci_7_173
PubMedSearch : Hue_2007_Invert.Neurosci_7_173
PubMedID: 17710455

Title : A hypothesis to account for the selective and diverse actions of neonicotinoid insecticides at their molecular targets, nicotinic acetylcholine receptors: catch and release in hydrogen bond networks - Ihara_2007_Invert.Neurosci_7_47
Author(s) : Ihara M , Shimomura M , Ishida C , Nishiwaki H , Akamatsu M , Sattelle DB , Matsuda K
Ref : Invert Neurosci , 7 :47 , 2007
Abstract : The low mammalian toxicity of neonicotinoid insecticides has been shown to be attributable, at least in part, to their selective actions on insect nicotinic acetylcholine receptors (nAChRs). There are multiple nAChRs in insects and a wealth of neonicotinoid chemicals. Studies to date have discribed a wide range of effects on nAChRs, notably partial agonist, super agonist and antagonist actions. Both the diversity of the neonicotinoid actions and their selectivity for insect over vertebrate nAChRs are the result of physicochemical and steric interactions at their molecular targets (nAChRs). In such interactions, the formation and breakage of hydrogen bond (HB) networks plays a key role. Therefore the loss or gain of even a single HB resulting from either structural changes in neonicotinoids, or the amino acid sequence of a particular nAChR subunit, could result in a drastic modification of neonicotinoid actions. In addition to the amino acid residues, the backbone carbonyl of nAChRs may also be involved in the formation of HB networks with neonicotinoids.
ESTHER : Ihara_2007_Invert.Neurosci_7_47
PubMedSearch : Ihara_2007_Invert.Neurosci_7_47
PubMedID: 17265057

Title : The Abeta1-42M35C mutated amyloid peptide Abeta1-42 and the 25-35 fragment fail to mimic the subtype-specificity of actions on recombinant human nicotinic acetylcholine receptors (alpha7, alpha4beta2, alpha3beta4) - Pym_2007_Neurosci.Lett_427_28
Author(s) : Pym LJ , Buckingham SD , Tsetlin V , Boyd CA , Sattelle DB
Ref : Neuroscience Letters , 427 :28 , 2007
Abstract : Alzheimer's disease (AD) is a neurodegenerative condition involving accumulation of the beta-amyloid peptide, Abeta1-42. Previously we have shown that amyloid peptides (Abeta1-42, Abeta1-40) have different actions on the three major brain nicotinic acetylcholine receptor (nAChR) subtypes (alpha7, alpha4beta2 and alpha3beta4). The methionine in position 35 of Abeta (M35) has been shown to be important in the toxicity of Abeta and the 25-35 fragment can mimic some of the actions of the Abeta1-42 peptide. However, the extent to which this mutant and the fragment mimic subtype selectivity is unknown. Two-electrode voltage-clamp electrophysiology has been used to study the actions on alpha7, alpha4beta2 and alpha3beta4 recombinant nAChRs expressed in Xenopus laevis oocytes of full length Abeta1-42, and Abeta peptide fragments, scrambled peptides, and the Abeta1-42 peptide containing mutations of the methionine in position 35. The Abeta25-35 fragment did not display subunit specificity. Abeta1-42 with an M35C mutation showed similar subtype-specificity to wild-type Abeta1-42. However, Abeta1-42 with an M35V substitution reduced the peak amplitude of ACh-induced currents recorded from alpha4beta2 nAChRs, but did not affect those recorded from alpha7 or alpha3beta4. These results indicate that the amino acid in position 35 of Abeta1-42 is an important determinant of the subtype-specificity of this peptide on human recombinant alpha7, alpha4beta2 and alpha3beta4 nAChRs and that the 25-35 fragment fails to mimic all of the actions of the full-length peptide.
ESTHER : Pym_2007_Neurosci.Lett_427_28
PubMedSearch : Pym_2007_Neurosci.Lett_427_28
PubMedID: 17945421

Title : Insect nicotinic acetylcholine receptor gene families: from genetic model organism to vector, pest and beneficial species - Jones_2007_Invert.Neurosci_7_67
Author(s) : Jones AK , Brown LA , Sattelle DB
Ref : Invert Neurosci , 7 :67 , 2007
Abstract : Nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic transmission in the insect nervous system and are targets of a major group of insecticides, the neonicotinoids. Analyses of genome sequences have shown that nAChR gene families remain compact in diverse insect species, when compared to their mammalian counterparts. Thus, Drosophila melanogaster and Anopheles gambiae each possess 10 nAChR genes while Apis mellifera has 11. Although these are among the smallest nAChR gene families known, receptor diversity can be considerably increased by alternative splicing and mRNA A-to-I editing, thereby generating species-specific subunit isoforms. In addition, each insect possesses at least one highly divergent nAChR subunit. Species-specific subunit diversification may offer promising targets for future rational design of insecticides that act on particular pests while sparing beneficial insects. Electrophysiological studies on cultured Drosophila cholinergic neurons show partial agonist actions of the neonicotinoid imidacloprid and super-agonist actions of another neonicotinoid, clothianidin, on native nAChRs. Recombinant hybrid heteromeric nAChRs comprising Drosophila Dalpha2 and a vertebrate beta2 subunit have been instructive in mimicking such actions of imidacloprid and clothianidin. Unitary conductance measurements on native nAChRs indicate that more frequent openings of the largest conductance state may offer an explanation for the superagonist actions of clothianidin.
ESTHER : Jones_2007_Invert.Neurosci_7_67
PubMedSearch : Jones_2007_Invert.Neurosci_7_67
PubMedID: 17216517

Title : The nicotinic acetylcholine receptor gene family of the nematode Caenorhabditis elegans: an update on nomenclature - Jones_2007_Invert.Neurosci_7_129
Author(s) : Jones AK , Davis P , Hodgkin J , Sattelle DB
Ref : Invert Neurosci , 7 :129 , 2007
Abstract : The simple nematode, Caenorhabditis elegans, possesses the most extensive known gene family of nicotinic acetylcholine receptor (nAChR)-like subunits. Whilst all show greatest similarity with nAChR subunits of both invertebrates and vertebrates, phylogenetic analysis suggests that just over half of these (32) may represent other members of the cys-loop ligand-gated ion channel superfamily. We have introduced a novel nomenclature system for these "Orphan" subunits, designating them as lgc genes (ligand-gated ion channels of the cys-loop superfamily), which can also be applied in future to unnamed and uncharacterised members of the cys-loop ligand-gated ion channel superfamily. We present here the resulting updated version of the C. elegans nAChR gene family and related ligand-gated ion channel genes.
ESTHER : Jones_2007_Invert.Neurosci_7_129
PubMedSearch : Jones_2007_Invert.Neurosci_7_129
PubMedID: 17503100

Title : The cys-loop ligand-gated ion channel superfamily of the honeybee, Apis mellifera - Jones_2006_Invert.Neurosci_6_123
Author(s) : Jones AK , Sattelle DB
Ref : Invert Neurosci , 6 :123 , 2006
Abstract : Members of the cys-loop ligand-gated ion channel (cys-loop LGIC) superfamily mediate neurotransmission in insects and are targets of successful insecticides. We have described the cys-loop LGIC superfamily of the honeybee, Apis mellifera, which is an important crop pollinator and a key model for social interaction. The honeybee superfamily consists of 21 genes, which is slightly smaller than that of Drosophila melanogaster comprising 23 genes. As with Drosophila, the honeybee possesses ion channels gated by acetylcholine, gamma-amino butyric acid, glutamate and histamine as well as orthologs of the Drosophila pH-sensitive chloride channel (pHCl), CG8916, CG12344 and CG6927. Similar to Drosophila, honeybee cys-loop LGIC diversity is broadened by differential splicing which may also serve to generate species-specific receptor isoforms. These findings on Apis mellifera enhance our understanding of cys-loop LGIC functional genomics and provide a useful basis for the development of improved insecticides that spare a major beneficial insect species.
ESTHER : Jones_2006_Invert.Neurosci_6_123
PubMedSearch : Jones_2006_Invert.Neurosci_6_123
PubMedID: 16902773

Title : Effects of amyloid peptides on A-type K+ currents of Drosophila larval cholinergic neurons - Kidd_2006_J.Neurobiol_66_476
Author(s) : Kidd JF , Brown LA , Sattelle DB
Ref : Journal of Neurobiology , 66 :476 , 2006
Abstract : Accumulation of amyloid (Abeta) peptides has been suggested to be the primary event in Alzheimer's disease. In neurons, K+ channels regulate a number of processes, including setting the resting potential, keeping action potentials short, timing interspike intervals, synaptic plasticity, and cell death. In particular, A-type K+ channels have been implicated in the onset of LTP in mammalian neurons, which is thought to underlie learning and memory. A number of studies have shown that Abeta peptides alter the properties of K+ currents in mammalian neurons. We set out to determine the effects of Abeta peptides on the neuronal A-type K+ channels of Drosophila. Treatment of cells for 18 h with 1 microM Abeta1-42 altered the kinetics of the A-type K+ current, shifting steady-state inactivation to more depolarized potentials and increasing the rate of recovery from inactivation. It also caused a decrease in neuronal viability. Thus it seems that alteration in the properties of the A-type K+ current is a prelude to the amyloid-induced death of neurons. This alteration in the properties of the A-type K+ current may provide a basis for the early memory impairment that was observed prior to neurodegeneration in a recent study of a transgenic Drosophila melanogaster line over-expressing the human Abeta1-42 peptide.
ESTHER : Kidd_2006_J.Neurobiol_66_476
PubMedSearch : Kidd_2006_J.Neurobiol_66_476
PubMedID: 16470685

Title : The effects of amyloid peptides on A-type K(+) currents of Drosophila larval cholinergic neurons: modeled actions on firing properties - Kidd_2006_Invert.Neurosci_6_207
Author(s) : Kidd JF , Sattelle DB
Ref : Invert Neurosci , 6 :207 , 2006
Abstract : In a previous paper we described the actions of beta-amyloid on an A-type K(+) current from Drosophila 3(rd) Instar larval neurons. The results were a depolarizing shift in the steady-state voltage dependence of inactivation and an increase in the rate of recovery from inactivation of the current. In this work we have used the simulation program NEURON to construct a model cell. We then use the model to predict the effects of changing the A-type K(+) current as was observed in the amyloid treated neurons on the firing properties of the cell. We show that changing the steady-state voltage dependence of inactivation of the current to a more depolarized level as observed in experiments in beta-amyloid treated neurons causes an increase in the threshold for the initiation of repetitive firing. However, increasing the rate of recovery from inactivation had no effect. Changing both properties simultaneously had no additional effect over changing the voltage dependence of inactivation alone. Thus, a change in the steady-state properties of the A-type K(+ )current as seen in the amyloid-treated Drosophila cholinergic neurons is sufficient to alter the firing properties of the modeled cell.
ESTHER : Kidd_2006_Invert.Neurosci_6_207
PubMedSearch : Kidd_2006_Invert.Neurosci_6_207
PubMedID: 17106756

Title : Alpha7 mutants mimicking atypical motifs (YxxCC of loop-C, and E to H at -1' in TM2) in the C. elegans LEV-8 subunit affect nicotinic acetylcholine receptor function - Towers_2006_Invert.Neurosci_6_69
Author(s) : Towers PR , Pym L , Yokota M , Matsuda K , Sattelle DB
Ref : Invert Neurosci , 6 :69 , 2006
Abstract : The ACR-8-like group of C. elegans nicotinic acetylcholine receptor (nAChR) subunits contain unusual motifs in the ACh binding site and in the -1' position of transmembrane region two (TM2). Using site-directed mutagenesis (SDM) we have introduced these motifs into chicken alpha7 as it has not been possible to express C. elegans nAChR in vitro. Oocytes expressing alpha7 with the C. elegans binding motif show a reduced affinity and efficacy for both ACh and nicotine. The blocking action of the anthelmintic drug levamisole is reduced. The TM2 motif resulted in a non-functional receptor. We conclude that the TM2 motif profoundly restricts cation movement through the alpha7 channel but does not confer anion permeability. The altered form of the ACh binding motif is likely to result in a receptor with altered pharmacology, adding potential functional diversity at synapses in the nervous system and neuromuscular junctions of C. elegans.
ESTHER : Towers_2006_Invert.Neurosci_6_69
PubMedSearch : Towers_2006_Invert.Neurosci_6_69
PubMedID: 16758254

Title : Neonicotinoid insecticides display partial and super agonist actions on native insect nicotinic acetylcholine receptors - Brown_2006_J.Neurochem_99_608
Author(s) : Brown LA , Ihara M , Buckingham SD , Matsuda K , Sattelle DB
Ref : Journal of Neurochemistry , 99 :608 , 2006
Abstract : Nicotinic acetylcholine receptors (nAChRs) are present in high density in insect nervous tissue and are targeted by neonicotinoid insecticides. Improved understanding of the actions of these insecticides will assist in the development of new compounds. Here, we have used whole-cell patch-clamp recording of cholinergic neurons cultured from the central nervous system of 3rd instar Drosophila larvae to examine the actions of acetylcholine (ACh) and nicotine, as well as the neonicotinoids imidacloprid, clothianidin and P-CH-clothianidin on native nAChRs of these neurons. Dose-response data yield an EC(50) value for ACh of 19 microm. Both nicotine and imidacloprid act as low efficacy agonists at native nAChRs, evoking maximal current amplitudes 10-14% of those observed for ACh. Conversely, clothianidin and P-CH-clothianidin evoke maximal current amplitudes up to 56% greater than those evoked by 100 microm ACh in the same neurons. This is the first demonstration of 'super' agonist actions of an insecticide on native insect nAChRs. Cell-attached recordings indicate that super agonism results from more frequent openings at the largest (63.5 pS) conductance state observed.
ESTHER : Brown_2006_J.Neurochem_99_608
PubMedSearch : Brown_2006_J.Neurochem_99_608
PubMedID: 16899070

Title : Contributions from Caenorhabditis elegans functional genetics to antiparasitic drug target identification and validation: nicotinic acetylcholine receptors, a case study - Brown_2006_Int.J.Parasitol_36_617
Author(s) : Brown LA , Jones AK , Buckingham SD , Mee CJ , Sattelle DB
Ref : International Journal for Parasitology , 36 :617 , 2006
Abstract : Following the complete sequencing of the genome of the free-living nematode, Caenorhabditis elegans, in 1998, rapid advances have been made in assigning functions to many genes. Forward and reverse genetics have been used to identify novel components of synaptic transmission as well as determine the key components of antiparasitic drug targets. The nicotinic acetylcholine receptors (nAChRs) are prototypical ligand-gated ion channels. The functions of these transmembrane proteins and the roles of the different members of their extensive subunit families are increasingly well characterised. The simple nervous system of C. elegans possesses one of the largest nicotinic acetylcholine receptor gene families known for any organism and a combination of genetic, microarray, physiological and reporter gene expression studies have added greatly to our understanding of the components of nematode muscle and neuronal nAChR subtypes. Chemistry-to-gene screens have identified five subunits that are components of nAChRs sensitive to the antiparasitic drug, levamisole. A novel, validated target acting downstream of the levamisole-sensitive nAChR has also been identified in such screens. Physiology and molecular biology studies on nAChRs of parasitic nematodes have also identified levamisole-sensitive and insensitive subtypes and further subdivisions are under investigation.
ESTHER : Brown_2006_Int.J.Parasitol_36_617
PubMedSearch : Brown_2006_Int.J.Parasitol_36_617
PubMedID: 16620825

Title : Role in the selectivity of neonicotinoids of insect-specific basic residues in loop D of the nicotinic acetylcholine receptor agonist binding site - Shimomura_2006_Mol.Pharmacol_70_1255
Author(s) : Shimomura M , Yokota M , Ihara M , Akamatsu M , Sattelle DB , Matsuda K
Ref : Molecular Pharmacology , 70 :1255 , 2006
Abstract : The insecticide imidacloprid and structurally related neonicotinoids act selectively on insect nicotinic acetylcholine receptors (nAChRs). To investigate the mechanism of neonicotinoid selectivity, we have examined the effects of mutations to basic amino acid residues in loop D of the nAChR acetylcholine (ACh) binding site on the interactions with imidacloprid. The receptors investigated are the recombinant chicken alpha4beta2 nAChR and Drosophila melanogaster Dalpha2/chicken beta2 hybrid nAChR expressed in Xenopus laevis oocytes. Although mutations of Thr77 in loop D of the beta2 subunit resulted in a barely detectable effect on the imidacloprid concentration-response curve for the alpha4beta2 nAChR, T77R;E79V double mutations shifted the curve dramatically to higher affinity binding of imidacloprid. Likewise, T77K;E79R and T77N;E79R double mutations in the Dalpha2beta2 nAChR also resulted in a shift to a higher affinity for imidacloprid, which exceeded that observed for a single mutation of Thr77 to basic residues. By contrast, these double mutations scarcely influenced the ACh concentration-response curve, suggesting selective interactions with imidacloprid of the newly introduced basic residues. Computational, homology models of the agonist binding domain of the wild-type and mutant alpha4beta2 and Dalpha2beta2 nAChRs with imidacloprid bound were generated based on the crystal structures of acetylcholine binding proteins of Lymnaea stagnalis and Aplysia californica. The models indicate that the nitro group of imidacloprid interacts directly with the introduced basic residues at position 77, whereas those at position 79 either prevent or permit such interactions depending on their electrostatic properties, thereby explaining the observed functional changes resulting from site-directed mutagenesis.
ESTHER : Shimomura_2006_Mol.Pharmacol_70_1255
PubMedSearch : Shimomura_2006_Mol.Pharmacol_70_1255
PubMedID: 16868180

Title : The actions of the neonicotinoid imidacloprid on cholinergic neurons of Drosophila melanogaster - Jepson_2006_Invert.Neurosci_6_33
Author(s) : Jepson JE , Brown LA , Sattelle DB
Ref : Invert Neurosci , 6 :33 , 2006
Abstract : The neonicotinoid insecticide imidacloprid is an agonist on insect nicotinic acetylcholine receptors (nAChRs). We utilised fura-2-based calcium imaging to investigate the actions of imidacloprid on cultured GFP-tagged cholinergic neurons from the third instar larvae of the genetic model organism Drosophila melanogaster. We demonstrate dose-dependent increases in intracellular calcium ([Ca2+]i) in cholinergic neurons upon application of imidacloprid (10 nM-100 muM) that are blocked by nAChR antagonists mecamylamine (10 microM) and alpha-bungarotoxin (alpha-BTX, 1 microM). When compared to other (untagged) neurons, cholinergic neurons respond to lower concentrations of imidacloprid (10-100 nM) and exhibit larger amplitude responses to higher (1-100 microM) concentrations of imidacloprid. Although imidacloprid acts via nAChRs, increases in [Ca2+]i also involve voltage-gated calcium channels (VGCCs) in both groups of neurons. Thus, we demonstrate that cholinergic neurons express nAChRs that are highly sensitive to imidacloprid, and demonstrate a role for VGCCs in amplifying imidacloprid-induced increases in [Ca2+]i.
ESTHER : Jepson_2006_Invert.Neurosci_6_33
PubMedSearch : Jepson_2006_Invert.Neurosci_6_33
PubMedID: 16453147

Title : The nicotinic acetylcholine receptor gene family of the honey bee, Apis mellifera - Jones_2006_Genome.Res_16_1422
Author(s) : Jones AK , Raymond-Delpech V , Thany SH , Gauthier M , Sattelle DB
Ref : Genome Res , 16 :1422 , 2006
Abstract : Nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission and play roles in many cognitive processes. They are under intense research as potential targets of drugs used to treat neurodegenerative diseases and neurological disorders such as Alzheimer's disease and schizophrenia. Invertebrate nAChRs are targets of anthelmintics as well as a major group of insecticides, the neonicotinoids. The honey bee, Apis mellifera, is one of the most beneficial insects worldwide, playing an important role in crop pollination, and is also a valuable model system for studies on social interaction, sensory processing, learning, and memory. We have used the A. mellifera genome information to characterize the complete honey bee nAChR gene family. Comparison with the fruit fly Drosophila melanogaster and the malaria mosquito Anopheles gambiae shows that the honey bee possesses the largest family of insect nAChR subunits to date (11 members). As with Drosophila and Anopheles, alternative splicing of conserved exons increases receptor diversity. Also, we show that in one honey bee nAChR subunit, six adenosine residues are targeted for RNA A-to-I editing, two of which are evolutionarily conserved in Drosophila melanogaster and Heliothis virescens orthologs, and that the extent of editing increases as the honey bee lifecycle progresses, serving to maximize receptor diversity at the adult stage. These findings on Apis mellifera enhance our understanding of nAChR functional genomics and provide a useful basis for the development of improved insecticides that spare a major beneficial insect species.
ESTHER : Jones_2006_Genome.Res_16_1422
PubMedSearch : Jones_2006_Genome.Res_16_1422
PubMedID: 17065616

Title : Neonicotinoids show selective and diverse actions on their nicotinic receptor targets: electrophysiology, molecular biology, and receptor modeling studies - Matsuda_2005_Biosci.Biotechnol.Biochem_69_1442
Author(s) : Matsuda K , Shimomura M , Ihara M , Akamatsu M , Sattelle DB
Ref : Biosci Biotechnol Biochem , 69 :1442 , 2005
Abstract : Neonicotinoid insecticides, which act selectively on insect nicotinic acetylcholine receptors (nAChRs), are used worldwide for insect pest management. Studies that span chemistry, biochemistry, molecular biology, and electrophysiology have contributed to our current understanding of the important physicochemical and structural properties essential for neonicotinoid actions as well as key receptor residues contributing to the high affinity of neonicotinoids for insect nAChRs. Research to date suggests that electrostatic interactions and possibly hydrogen bond formation between neonicotinoids and nAChRs contribute to the selectivity of these chemicals. A rich diversity of neonicotinoid-nAChR interactions has been demonstrated using voltage-clamp electrophysiology. Computational modeling of nAChR-imidacloprid interaction has assisted in the interpretation of these results.
ESTHER : Matsuda_2005_Biosci.Biotechnol.Biochem_69_1442
PubMedSearch : Matsuda_2005_Biosci.Biotechnol.Biochem_69_1442
PubMedID: 16116270

Title : Edit, cut and paste in the nicotinic acetylcholine receptor gene family of Drosophila melanogaster - Sattelle_2005_Bioessays_27_366
Author(s) : Sattelle DB , Jones AK , Sattelle BM , Matsuda K , Reenan R , Biggin PC
Ref : Bioessays , 27 :366 , 2005
Abstract : Nicotinic acetylcholine receptors (nAChRs) are important for fast synaptic cholinergic transmission. They are targets of drugs/chemicals for human and animal health as well as for pest control. With the advent of genome sequencing, entire nAChR gene families have now been described for vertebrates and invertebrates. Mostly, these are extensive with a large number of distinct subunits, making possible many nAChR subtypes differing in transmitter affinity, channel conductance, ion selectivity, desensitization, modulation and pharmacology. The smallest nAChR gene family to date is that of the fruit fly, Drosophila melanogaster, with only 10 members. This apparently compact family belies its true diversity as 4 of the 10 subunits show alternative splicing. Also, using Drosophila, A-to-I pre-mRNA editing has been demonstrated for the first time in nAChRs. Such is the extent of this variation, that one subunit alone (Dalpha6) can potentially generate far more isoforms than seen in entire gene families from other species. We present here three-dimensional models constructed for insect nAChRs, which show that many variations introduced by alternative splicing and RNA editing may influence receptor function.
ESTHER : Sattelle_2005_Bioessays_27_366
PubMedSearch : Sattelle_2005_Bioessays_27_366
PubMedID: 15770687

Title : The Caenorhabditis elegans lev-8 gene encodes a novel type of nicotinic acetylcholine receptor alpha subunit - Towers_2005_J.Neurochem_93_1
Author(s) : Towers PR , Edwards B , Richmond JE , Sattelle DB
Ref : Journal of Neurochemistry , 93 :1 , 2005
Abstract : We have cloned Caenorhabditis elegans lev-8 and demonstrated that it encodes a novel nicotinic acetylcholine receptor (nAChR) subunit (previously designated ACR-13), which has functional roles in body wall and uterine muscles as part of a levamisole-sensitive receptor. LEV-8 is an alpha subunit and is the first to be described from the ACR-8-like group, a new class of nAChR with atypical acetylcholine-binding site (loop C) and channel-lining motifs. A single base pair change in the first intron of lev-8 in lev-8(x15) mutants leads to alternative splicing and the introduction of a premature stop codon. lev-8(x15) worms are partially resistant to levamisole-induced egg laying and paralysis, phenotypes rescued by expression of the wild-type gene. lev-8(x15) worms also show reduced rates of pharyngeal pumping. Electrophysiological recordings from body wall muscle show that currents recorded in response to levamisole have reduced amplitude in lev-8(x15) compared with wild-type animals. Consistent with these phenotypic observations, green fluorescent protein fused to LEV-8 is expressed in body wall and uterine muscle, motor neurons and epithelial-derived socket cells. Thus, LEV-8 is a levamisole receptor subunit and exhibits the most diverse expression pattern of any invertebrate nAChR subunit studied to date.
ESTHER : Towers_2005_J.Neurochem_93_1
PubMedSearch : Towers_2005_J.Neurochem_93_1
PubMedID: 15773900

Title : A7DB: a relational database for mutational, physiological and pharmacological data related to the alpha7 nicotinic acetylcholine receptor - Buckingham_2005_BMC.Neurosci_6_2
Author(s) : Buckingham SD , Pym L , Jones AK , Brown L , Sansom MS , Sattelle DB , Biggin PC
Ref : BMC Neurosci , 6 :2 , 2005
Abstract : BACKGROUND: Nicotinic acetylcholine receptors (nAChRs) are pentameric proteins that are important drug targets for a variety of diseases including Alzheimer's, schizophrenia and various forms of epilepsy. One of the most intensively studied nAChR subunits in recent years has been alpha7. This subunit can form functional homomeric pentamers (alpha7)5, which can make interpretation of physiological and structural data much simpler. The growing amount of structural, pharmacological and physiological data for these receptors indicates the need for a dedicated and accurate database to provide a means to access this information in a coherent manner. DESCRIPTION: A7DB http:\/\/ is a new relational database of manually curated experimental physiological data associated with the alpha7 nAChR. It aims to store as much of the pharmacology, physiology and structural data pertaining to the alpha7 nAChR. The data is accessed via web interface that allows a user to search the data in multiple ways: 1) a simple text query 2) an incremental query builder 3) an interactive query builder and 4) a file-based uploadable query. It currently holds more than 460 separately reported experiments on over 85 mutations.
CONCLUSIONS: A7DB will be a useful tool to molecular biologists and bioinformaticians not only working on the alpha7 receptor family of proteins but also in the more general context of nicotinic receptor modelling. Furthermore it sets a precedent for expansion with the inclusion of all nicotinic receptor families and eventually all cys-loop receptor families.
ESTHER : Buckingham_2005_BMC.Neurosci_6_2
PubMedSearch : Buckingham_2005_BMC.Neurosci_6_2
PubMedID: 15661073

Title : Insect-vertebrate chimeric nicotinic acetylcholine receptors identify a region, loop B to the N-terminus of the Drosophila Dalpha2 subunit, which contributes to neonicotinoid sensitivity - Shimomura_2005_Neurosci.Lett_385_168
Author(s) : Shimomura M , Satoh H , Yokota M , Ihara M , Matsuda K , Sattelle DB
Ref : Neuroscience Letters , 385 :168 , 2005
Abstract : A chimera based on the chicken alpha4 nicotinic acetylcholine receptor (nAChR) subunit containing an insert from loop B to the N-terminus of the Drosophila melanogaster Dalpha2 (=SAD) subunit was constructed and co-expressed with the chicken beta2 nAChR subunit in Xenopus laevis oocytes. The actions of the neonicotinoid insecticide imidacloprid were examined. Replacement of the region loop B to the N-terminus of the alpha4 subunit by the corresponding region of the Dalpha2 subunit had little effect on the concentration-response curve for imidacloprid. However, replacement of Glu219 by proline in the YXCC motif in loop C of the chimeric alpha4 subunit resulted in a marked displacement to the left of the concentration-response curve for imidacloprid not seen when an equivalent mutation was made in the alpha4beta2 nAChR. The results suggest that the region loop B to the N-terminus in the Dalpha2 subunit contributes to the high imidacloprid sensitivity of the hybrid Dalpha2beta2 nAChR.
ESTHER : Shimomura_2005_Neurosci.Lett_385_168
PubMedSearch : Shimomura_2005_Neurosci.Lett_385_168
PubMedID: 15963641

Title : Subtype-specific actions of beta-amyloid peptides on recombinant human neuronal nicotinic acetylcholine receptors (alpha7, alpha4beta2, alpha3beta4) expressed in Xenopus laevis oocytes - Pym_2005_Br.J.Pharmacol_146_964
Author(s) : Pym L , Kemp M , Raymond-Delpech V , Buckingham S , Boyd CA , Sattelle DB
Ref : British Journal of Pharmacology , 146 :964 , 2005
Abstract : Two-electrode voltage-clamp electrophysiology has been used to study the actions of two amyloid peptides (Abeta(1-42), Abeta(1-40)) on alpha7, alpha4beta2 and alpha3beta4 recombinant human neuronal nicotinic acetylcholine receptors (nicotinic AChRs), heterologously expressed in Xenopus laevis oocytes. The application of Abeta(1-42) or Abeta(1-40) (1 pM-100 nM) for 5 s does not directly activate expressed human alpha7, alpha4beta2 or alpha3beta4 nicotinic AChRs.Abeta(1-42) and Abeta(1-40) are antagonists of alpha7 nicotinic AChRs. For example, 10 nM Abeta(1-42) and Abeta(1-40) both reduced the peak amplitude of currents recorded (3 mM ACh) to 48+/-5 and 45+/-10% (respectively) of control currents recorded in the absence of peptide. In both the cases the effect is sustained throughout a 30 min peptide application and is poorly reversible.Abeta(1-42) and Abeta(1-40) (10 nM) enhance currents recorded in response to ACh (3 mM) from oocytes expressing alpha4beta2 nicotinic AChRs by 195+/-40 and 195+/-41% respectively. This effect is transient, reaching a peak after 3 min and returning to control values after a 24 min application of 10 nM Abeta(1-42). We observe an enhancement of 157+/-22% of control ACh-evoked current amplitude in response to 100 nM Abeta(1-42) recorded from oocytes expressing alpha4beta2 nicotinic AChRs.Abeta(1-42) and Abeta(1-40) (10 nM) were without antagonist actions on the responses of alpha3beta4 nicotinic AChRs to ACh (1 nM-3 mM).
ESTHER : Pym_2005_Br.J.Pharmacol_146_964
PubMedSearch : Pym_2005_Br.J.Pharmacol_146_964
PubMedID: 16184187

Title : Ion channels: molecular targets of neuroactive insecticides - Raymond-Delpech_2005_Invert.Neurosci_5_119
Author(s) : Raymond-Delpech V , Matsuda K , Sattelle BM , Rauh JJ , Sattelle DB
Ref : Invert Neurosci , 5 :119 , 2005
Abstract : Many of the insecticides in current use act on molecular targets in the insect nervous system. Recently, our understanding of these targets has improved as a result of the complete sequencing of an insect genome, i.e., Drosophila melanogaster. Here we examine the recent work, drawing on genetics, genomics and physiology, which has provided evidence that specific receptors and ion channels are targeted by distinct chemical classes of insect control agents. The examples discussed include, sodium channels (pyrethroids, p,p'-dichlorodiphenyl-trichloroethane (DDT), dihydropyrazoles and oxadiazines); nicotinic acetylcholine receptors (cartap, spinosad, imidacloprid and related nitromethylenes/nitroguanidines); gamma-aminobutyric acid (GABA) receptors (cyclodienes, gamma-BHC and fipronil) and L-glutamate receptors (avermectins). Finally, we have examined the molecular basis of resistance to these molecules, which in some cases involves mutations in the molecular target, and we also consider the future impact of molecular genetic technologies in our understanding of the actions of neuroactive insecticides.
ESTHER : Raymond-Delpech_2005_Invert.Neurosci_5_119
PubMedSearch : Raymond-Delpech_2005_Invert.Neurosci_5_119
PubMedID: 16172884

Title : The nicotinic acetylcholine receptor gene family of the malaria mosquito, Anopheles gambiae - Jones_2005_Genomics_85_176
Author(s) : Jones AK , Grauso M , Sattelle DB
Ref : Genomics , 85 :176 , 2005
Abstract : Nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission in the insect nervous system and are targets of widely selling insecticides. We have identified the nAChR gene family from the genome of the malaria mosquito vector, Anopheles gambiae, to be the second complete insect nAChR gene family described following that of Drosophila melanogaster. Like Drosophila, Anopheles possesses 10 nAChR subunits with orthologous relationships evident between the two insects. Interestingly, the Anopheles orthologues of Dbeta2 and Dbeta3 possess the vicinal cysteines that define alpha subunits. As with Dalpha4 and Dalpha6, the Anopheles orthologues are alternatively spliced at equivalent exons. Reverse transcription-polymerase chain reaction analysis shows that RNA A-to-I editing sites conserved between Dalpha6 of Drosophila and alpha7-2 of the tobacco budworm, Heliothis virescens, are not shared with the equivalent nAChR subunit of Anopheles. Indeed, RNA-editing sites identified in functionally significant regions of Dbeta1, Dalpha5, and Dalpha6 are not conserved in the mosquito orthologues, indicating considerable divergence of RNA molecules targeted for editing within the insect order Diptera. These findings shed further light on the diversity of nAChR subunits and may present a useful basis for the development of improved malaria control agents by enhancing our understanding of a validated mosquito insecticide target.
ESTHER : Jones_2005_Genomics_85_176
PubMedSearch : Jones_2005_Genomics_85_176
PubMedID: 15676276

Title : Sgbeta1, a novel locust (Schistocerca gregaria) non-alpha nicotinic acetylcholine receptor-like subunit with homology to the Drosophila melanogaster Dbeta1 subunit - Jones_2005_Invert.Neurosci_5_147
Author(s) : Jones AK , Marshall J , Blake AD , Buckingham SD , Darlison MG , Sattelle DB
Ref : Invert Neurosci , 5 :147 , 2005
Abstract : The cloning, sequencing and functional expression of Sgbeta1, a novel locust (Schistocerca gregaria) non-alpha nicotinic acetylcholine receptor (nAChR) subunit is described. This subunit shows 80% identity with the Drosophila melanogaster Dbeta1 and 92% identity with the Locusta migratoria beta1, non-alpha subunits but only 38% identity to Sgalpha1 (also referred to as alphaL1), a previously cloned S. gregaria nAChR alpha-subunit. When expressed in Xenopus laevis oocytes, Sgbeta1 does not respond to nicotine. Responses to nicotine are observed, however, in oocytes co-expressing Sgalpha1 and Sgbeta1, but the pharmacology is indistinguishable from that of currents produced by expressing Sgalpha1 alone. We conclude that either Sgbeta1 does not co-assemble with Sgalpha1, or that it is unable to contribute to the functional properties of the receptor, in the Xenopus oocyte expression system.
ESTHER : Jones_2005_Invert.Neurosci_5_147
PubMedSearch : Jones_2005_Invert.Neurosci_5_147
PubMedID: 16177887

Title : Alpha7-acetylcholine receptor antibodies in two patients with Rasmussen encephalitis - Watson_2005_Neurology_65_1802
Author(s) : Watson R , Jepson JE , Bermudez I , Alexander S , Hart Y , McKnight K , Roubertie A , Fecto F , Valmier J , Sattelle DB , Beeson D , Vincent A , Lang B
Ref : Neurology , 65 :1802 , 2005
Abstract : Rasmussen encephalitis (RE) sera were screened for antibodies to human alpha7 nicotinic acetylcholine receptors (nAChRs) using electrophysiology, calcium imaging, and ligand binding assays. Sera from two of nine patients with RE blocked ACh-induced currents through alpha7 nAChRs and the ACh-induced rise in intracellular free calcium ([Ca2+]i) and inhibited (125)I-alpha-bungarotoxin binding in cells expressing alpha7 nAChRs. Thus, the alpha7 nAChR is a potential target for pathogenic antibodies in patients with RE.
ESTHER : Watson_2005_Neurology_65_1802
PubMedSearch : Watson_2005_Neurology_65_1802
PubMedID: 16344526

Title : Molecular and functional diversity in the nicotinic acetylcholine receptor gene families of Caenorhabditis elegans and Drosophila melanogaster. -
Author(s) : Sattelle DB , Culetto E , Jones AK
Ref : Cholinergic Mechanisms, CRC Press :199 , 2004

Title : Roles of loop C and the loop B-C interval of the nicotinic receptor alpha subunit in its selective interactions with imidacloprid in insects - Shimomura_2004_Neurosci.Lett_363_195
Author(s) : Shimomura M , Yokota M , Matsuda K , Sattelle DB , Komai K
Ref : Neuroscience Letters , 363 :195 , 2004
Abstract : To elucidate the mechanism of selective action of imidacloprid on insect nicotinic acetylcholine receptors (nAChRs), we examined the roles of loop C and the loop B-C interval region in receptor interactions with imidacloprid. The P242E mutation in loop C of the Drosophila SAD subunit (the second alpha-like Drosophila nicotinic acetylcholine receptor subunit, also called Dalpha2 subunit) reduced imidacloprid sensitivity of the SAD-chicken beta2 hybrid nAChR, whereas the E219P mutation of the alpha4 subunit increased the imidacloprid sensitivity of the alpha4beta2 nAChR. Deletion of the loop B-C interval region from the SAD subunit enhanced the effect of the P242E mutation on the SADbeta2 hybrid nAChR, suggesting important roles of the regions investigated in the nAChR-imidacloprid interactions.
ESTHER : Shimomura_2004_Neurosci.Lett_363_195
PubMedSearch : Shimomura_2004_Neurosci.Lett_363_195
PubMedID: 15182942

Title : The Caenorhabditis elegans unc-63 gene encodes a levamisole-sensitive nicotinic acetylcholine receptor alpha subunit - Culetto_2004_J.Biol.Chem_279_42476
Author(s) : Culetto E , Baylis HA , Richmond JE , Jones AK , Fleming JT , Squire MD , Lewis JA , Sattelle DB
Ref : Journal of Biological Chemistry , 279 :42476 , 2004
Abstract : The anthelmintic drug levamisole causes hypercontraction of body wall muscles and lethality in nematode worms. In the nematode Caenorhabditis elegans, a genetic screen for levamisole resistance has identified 12 genes, three of which (unc-38, unc-29, and lev-1) encode nicotinic acetylcholine receptor (nAChR) subunits. Here we describe the molecular and functional characterization of another levamisole-resistant gene, unc-63, encoding a nAChR alpha subunit with a predicted amino acid sequence most similar to that of UNC-38. Like UNC-38 and UNC-29, UNC-63 is expressed in body wall muscles. In addition, UNC-63 is expressed in vulval muscles and neurons. We also show that LEV-1 is expressed in body wall muscle, thus overlapping the cellular localization of UNC-63, UNC-38, and UNC-29 and suggesting possible association in vivo. This is supported by electrophysiological studies on body wall muscle, which demonstrate that a levamisole-sensitive nAChR present at the C. elegans neuromuscular junction requires both UNC-63 and LEV-1 subunits. Thus, at least four subunits, two alpha types (UNC-38 and UNC-63) and two non-alpha types (UNC-29 and LEV-1), can contribute to levamisole-sensitive muscle nAChRs in nematodes.
ESTHER : Culetto_2004_J.Biol.Chem_279_42476
PubMedSearch : Culetto_2004_J.Biol.Chem_279_42476
PubMedID: 15280391

Title : Super agonist actions of clothianidin and related compounds on the SAD beta 2 nicotinic acetylcholine receptor expressed in Xenopus laevis oocytes - Ihara_2004_Biosci.Biotechnol.Biochem_68_761
Author(s) : Ihara M , Matsuda K , Shimomura M , Sattelle DB , Komai K
Ref : Biosci Biotechnol Biochem , 68 :761 , 2004
Abstract : To compare the actions of clothianidin, a neonicotinoid acting on insect nicotinic acetylcholine receptors, and related compounds with that of imidacloprid, the compounds were tested on the Drosophila SAD-chicken beta2 nicotinic acetylcholine receptor expressed in Xenopus laevis oocytes using two-electrode voltage-clamp electrophysiology. The maximum response of the SAD beta 2 nicotinic receptor to clothianidin was larger than that observed for acetylcholine. Ring breakage of the imidazolidine ring of imidacloprid resulting in the generation of a guanidine group was critical for this super agonist action.
ESTHER : Ihara_2004_Biosci.Biotechnol.Biochem_68_761
PubMedSearch : Ihara_2004_Biosci.Biotechnol.Biochem_68_761
PubMedID: 15056916

Title : Functional genomics of the nicotinic acetylcholine receptor gene family of the nematode, Caenorhabditis elegans - Jones_2004_Bioessays_26_39
Author(s) : Jones AK , Sattelle DB
Ref : Bioessays , 26 :39 , 2004
Abstract : Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that bring about a diversity of fast synaptic actions. Analysis of the Caenorhabditis elegans genome has revealed one of the most-extensive and diverse nAChR gene families known, consisting of at least 27 subunits. Striking variation with possible functional implications has been observed in normally conserved motifs at the acetylcholine-binding site and in the channel-lining region. Some nAChR subunits are particular to neurons whilst others are present in both neurons and muscles. The localization of subunits in non-synaptic regions suggests novel roles for nAChRs. Genetic and heterologous expression studies have identified a subset of nAChR subunits that are important drug targets while the study of mutants has identified genes functionally-linked to nAChRs. Future studies using C. elegans offer the prospect of increasing our understanding of the functional diversity of a complex nAChR gene family as well as addressing the role of nAChRs and associated proteins in human disorders.
ESTHER : Jones_2004_Bioessays_26_39
PubMedSearch : Jones_2004_Bioessays_26_39
PubMedID: 14696039

Title : Spatiotemporal calcium signaling in a Drosophila melanogaster cell line stably expressing a Drosophila muscarinic acetylcholine receptor - Cordova_2003_Invert.Neurosci_5_19
Author(s) : Cordova D , Delpech VR , Sattelle DB , Rauh JJ
Ref : Invert Neurosci , 5 :19 , 2003
Abstract : A muscarinic acetylcholine receptor (mAChR), DM1, expressed in the nervous system of Drosophila melanogaster, has been stably expressed in a Drosophila S2 cell line (S2-DM1) and used to investigate spatiotemporal calcium changes following agonist activation. Carbamylcholine (CCh) and oxotremorine are potent agonists, whereas application of the vertebrate M1 mAChR agonist, McN-A-343, results in a weak response. Activation of S2-DM1 receptors using CCh resulted in an increase in intracellular calcium ([Ca(2+)](i)) that was biphasic. Two distinct calcium sources were found to contribute to calcium signaling: (1) internal stores that are sensitive to both thapsigargin and 2-aminoethoxydiphenyl borate and (2) capacitative calcium entry. Spatiotemporal imaging of individual S2-DM1 cells showed that the CCh-induced [Ca(2+)](i) transient resulted from a homogeneous calcium increase throughout the cell, indicative of calcium release from internal stores. In contrast, ionomycin induced the formation of a "calcium ring" at the cell periphery, consistent with external calcium influx.
ESTHER : Cordova_2003_Invert.Neurosci_5_19
PubMedSearch : Cordova_2003_Invert.Neurosci_5_19
PubMedID: 12827518

Title : Combinatorial mutations in loops D and F strongly influence responses of the alpha7 nicotinic acetylcholine receptor to imidacloprid - Shimomura_2003_Brain.Res_991_71
Author(s) : Shimomura M , Yokota M , Okumura M , Matsuda K , Akamatsu M , Sattelle DB , Komai K
Ref : Brain Research , 991 :71 , 2003
Abstract : The nitro group of a neonicotinoid, imidacloprid, plays a key role in its selective actions on insect nicotinic acetylcholine receptors (nicotinic AChRs) and is postulated to bind close to residues Q79 in loop D and G189 in loop F of the chicken alpha7 nicotinic AChR. To evaluate the relative contributions of these residues to interactions with imidacloprid, Q79 and G189 were replaced in tandem by first basic then acidic residues. Changes in the currents evoked by imidacloprid and acetylcholine (ACh) on the alpha7 wild type and mutant receptors expressed in Xenopus laevis oocytes were investigated using two-electrode voltage clamp electrophysiology. An increase in the efficacy of imidacloprid for the alpha7 receptor resulting from the Q79K and Q79R mutations was suppressed by a G189E mutation in loop F. However, the increases in efficacy resulting from such Q79 mutations were scarcely influenced by a G189D substitution. Three-dimensional modeling of the alpha7 nicotinic AChR, based on the acetylcholine-binding protein (AChBP) of Lymnaea stagnalis, suggests that the reduced efficacy of imidacloprid following the G189E mutation is likely to result from carboxylate interference with the electronic interactions between the nitro group of imidacloprid and the basic residues in loop D.
ESTHER : Shimomura_2003_Brain.Res_991_71
PubMedSearch : Shimomura_2003_Brain.Res_991_71
PubMedID: 14575878

Title : Diverse actions of neonicotinoids on chicken alpha7, alpha4beta2 and Drosophila-chicken SADbeta2 and ALSbeta2 hybrid nicotinic acetylcholine receptors expressed in Xenopus laevis oocytes - Ihara_2003_Neuropharmacol_45_133
Author(s) : Ihara M , Matsuda K , Otake M , Kuwamura M , Shimomura M , Komai K , Akamatsu M , Raymond V , Sattelle DB
Ref : Neuropharmacology , 45 :133 , 2003
Abstract : The 2-nitroimino-imidazolidine and related moieties are structural features of neonicotinoid insecticides acting on nicotinic acetylcholine receptors (nicotinic AChRs). To evaluate these moieties in neonicotinoid interactions with nicotinic AChR alpha subunits, the actions of imidacloprid and related compounds on the chicken alpha7, alpha4beta2 and Drosophila melanogaster-chicken hybrid (SADbeta2 and ALSbeta2) receptors expressed in Xenopus laevis oocytes were studied by voltage-clamp electrophysiology. Imidacloprid and nitenpyram were partial agonists and a nitromethylene analog of imidacloprid (CH-IMI) was a full agonist of the alpha7 receptor, whereas their agonist actions on the alpha4beta2 receptor were very weak, contrasting with full agonist actions of DN-IMI, a desnitro derivative of imidacloprid. The neonicotinoids and DN-IMI were either full or partial agonists of the SADbeta2 receptors. Nitenpyram and DN-IMI were partial agonists of the ALSbeta2 receptor, whereas imidacloprid and CH-IMI scarcely activated the ALSbeta2 receptor. Imidacloprid and CH-IMI in fact suppressed ACh-induced responses of the ALSbeta2 receptor, whereas imidacloprid potentiated and CH-IMI suppressed ACh-induced responses of the alpha4beta2 receptor. These results suggest that interactions with alpha subunits of the 2-nitroimino-imidazolidine moiety of imidacloprid play a role in determining not only agonist and antagonist actions on all four receptors, but also the potentiation of ACh-induced responses of the alpha4beta2 receptor.
ESTHER : Ihara_2003_Neuropharmacol_45_133
PubMedSearch : Ihara_2003_Neuropharmacol_45_133
PubMedID: 12814666

Title : Action of nereistoxin on recombinant neuronal nicotinic acetylcholine receptors expressed in Xenopus laevis oocytes - Raymond_2003_Invert.Neurosci_5_29
Author(s) : Raymond Delpech V , Ihara M , Coddou C , Matsuda K , Sattelle DB
Ref : Invert Neurosci , 5 :29 , 2003
Abstract : Nereistoxin (NTX), a natural neurotoxin from the salivary glands of the marine annelid worm Lumbriconereis heteropoda, is highly toxic to insects. Its synthetic analogue, Cartap, was the first commercial insecticide based on a natural product. We have used voltage-clamp electrophysiology to compare the actions of NTX on recombinant nicotinic acetylcholine receptors (nicotinic AChRs) expressed in Xenopus laevis oocytes following nuclear injection of cDNAs. The recombinant nicotinic AChRs investigated were chicken alpha7, chicken alpha4beta2 and the Drosophila melanogaster/chicken hybrid receptors SAD/beta2 and ALS/beta2. No agonist action of NTX (0.1-100 microM) was observed on chicken alpha7, chicken alpha4beta2 and the Drosophila/chicken hybrid nicotinic AChRs. Currents elicited by ACh were reduced in amplitude by NTX in a dose-dependent manner. The toxin was slightly more potent on recombinant Drosophila/vertebrate hybrid receptors than on vertebrate homomeric (alpha7) or heteromeric (alpha4beta2) nicotinic AChRs. Block by NTX of the chicken alpha7, chicken alpha4beta2 and the SAD/beta2 and ALS/beta2 Drosophila/chicken hybrid receptors is in all cases non-competitive. Thus, the site of action on nicotinic AChRs of NTX, to which the insecticide Cartap is metabolised in insects, differs from that of the major nicotinic AChR-active insecticide, imidacloprid.
ESTHER : Raymond_2003_Invert.Neurosci_5_29
PubMedSearch : Raymond_2003_Invert.Neurosci_5_29
PubMedID: 14608492

Title : The nicotinic acetylcholine receptor gene family of the pufferfish, Fugu rubripes - Jones_2003_Genomics_82_441
Author(s) : Jones AK , Elgar G , Sattelle DB
Ref : Genomics , 82 :441 , 2003
Abstract : Nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission at nerve-muscle junctions and in the brain. However, the complete gene family of nAChRs has not so far been reported for any vertebrate organism. We have identified the complete nAChR gene family from the reference genome of the pufferfish, Fugu rubripes. It consists of 16 alpha and 12 non-alpha candidate subunits, making it the largest vertebrate nAChR gene family known to date. The gene family includes an unusual set of muscle-like nAChR subunits comprising two alpha1s, two beta1s, one delta, one epsilon, and one gamma. One of the beta1 subunits possesses an aspartate residue and N-glycosylation sites hitherto shown to be necessary for delta-subunit function. Potential Fugu orthologs of neuronal nAChR subunits alpha2-4, alpha6, and beta2-4 have been identified. Interestingly, the Fugu alpha5 counterpart appears to be a non-alpha subunit. Fugu possesses an expanded set of alpha7-9-like subunits and no alpha10 ortholog has been found. Two new candidate beta subtypes, designated beta5 and beta6, may represent subunits yet to be found in the human genome. The Fugu nAChR gene structures are considerably more diverse than those of higher vertebrates, with evidence of "intron gain" in many cases. We show, using RT-PCR, that the Fugu nAChR subunits are expressed in a variety of tissues.
ESTHER : Jones_2003_Genomics_82_441
PubMedSearch : Jones_2003_Genomics_82_441
PubMedID: 13679024

Title : Novel animal-health drug targets from ligand-gated chloride channels - Raymond_2002_Nat.Rev.Drug.Discov_1_427
Author(s) : Raymond V , Sattelle DB
Ref : Nat Rev Drug Discov , 1 :427 , 2002
Abstract : The world's three best-selling veterinary antiparasitic drugs ('parasiticides') act on ligand-gated ion channels. The sequencing of the complete genomes of the invertebrate genetic model organisms Caenorhabditis elegans and Drosophila melanogaster has led to the recent cloning of new subunits of 5-hydroxytryptamine-gated and histamine-gated chloride channels. Together with L-glutamate-gated chloride channels, which are important targets of known parasiticides, and acetylcholine-gated chloride channels, these new classes of ligand-gated chloride channels, which are known only from invertebrates, add to our understanding of inhibitory neural signalling. They could offer the prospect of being targets for a new generation of selective drugs to control nematode and insect parasites.
ESTHER : Raymond_2002_Nat.Rev.Drug.Discov_1_427
PubMedSearch : Raymond_2002_Nat.Rev.Drug.Discov_1_427
PubMedID: 12119744

Title : Functional genomics of ionotropic acetylcholine receptors in Caenorhabditis elegans and Drosophila melanogaster - Sattelle_2002_Novartis.Found.Symp_245_240
Author(s) : Sattelle DB , Culetto E , Grauso M , Raymond V , Franks CJ , Towers P
Ref : Novartis Found Symp , 245 :240 , 2002
Abstract : Genetics, genomics and electrophysiology are transforming our understanding of the nicotinic acetylcholine receptors (nAChRs). Caenorhabditis elegans contains the largest known family of nAChR subunit genes (27 members), while Drosophila melanogaster contains an exclusively neuronal nAChR gene family (10 members). In C. elegans, several genetic screens have enabled the identification of nAChR subunits, along with novel proteins that act upstream and downstream of functional nAChRs. The C. elegans genome project has identified many new candidate nAChR subunits and the calculated electrostatic potential energy profiles for the M2 channel-lining regions predict considerable functional diversity. The respective roles of subunits are under investigation using forward and reverse genetics. Electrophysiological and reporter gene studies have demonstrated roles for particular subunits in levamisole-sensitive muscle nAChRs and a role for nAChRs in pharyngeal pumping. Recombinant homomeric and heteromeric C. elegans nAChRs have been expressed in Xenopus laevis oocytes. In D. melanogaster, three new nAChR a subunits have been cloned, one of which shows multiple variant transcripts arising from alternative splicing and A-to-I pre-mRNA editing. Thus, studies on the genetic model organisms C. elegans and D. melanogaster have revealed different routes to generating molecular and functional diversity in the nAChR gene family and are providing new insights into the in vivo functions of individual family members.
ESTHER : Sattelle_2002_Novartis.Found.Symp_245_240
PubMedSearch : Sattelle_2002_Novartis.Found.Symp_245_240
PubMedID: 12027012

Title : Novel alpha7-like nicotinic acetylcholine receptor subunits in the nematode Caenorhabditis elegans - Mongan_2002_Protein.Sci_11_1162
Author(s) : Mongan NP , Jones AK , Smith GR , Sansom MS , Sattelle DB
Ref : Protein Science , 11 :1162 , 2002
Abstract : We have used reverse-transcription-polymerase chain reaction (RT-PCR) and DNA sequencing techniques to confirm the transcription of seven (six alpha and one non-alpha) novel candidate nicotinic acetylcholine receptor (nAChR) subunit-encoding genes identified in the genome sequence of the nematode Caenorhabditis elegans. Compared to vertebrate nAChR subunits, they most closely resemble the homomer-forming, neuronal alpha7 subunit. Comparison of the predicted amino acid sequences of the new nAChR subunits with those described previously in C. elegans reveals five subunits (four alpha and one non-alpha) which resemble the DEG-3-like group of subunits. To date, this highly divergent nAChR subunit group is unique to C. elegans. ACR-22 is the first non-alpha member of the DEG-3-like group of subunits to be identified. Two new members of the related ACR-16-like nAChR group of subunits have also been shown to be transcribed, making the ACR-16-like subunit group the largest in C. elegans. Residues in the alpha subunit second transmembrane region (M2) which contribute to the channel lining show variations with implications for channel function. For example, in ACR-22, the highly conserved 0' lysine of M2 is replaced by histidine. Restrained molecular dynamics simulations have been used to generate molecular models of homo-pentameric M2 helix bundles for the novel subunits, enabling identification and display of pore-lining and protein interface residues. The number and diversity of genes encoding C. elegans nAChR subunits with similarities to the homomer-forming vertebrate alpha7 subunits and the identification of related non-alpha subunits, only found in C. elegans to date, suggest that at least some of these subunits may contribute to heteromers in vivo.
ESTHER : Mongan_2002_Protein.Sci_11_1162
PubMedSearch : Mongan_2002_Protein.Sci_11_1162
PubMedID: 11967372

Title : Effects of mutations of a glutamine residue in loop D of the alpha7 nicotinic acetylcholine receptor on agonist profiles for neonicotinoid insecticides and related ligands - Shimomura_2002_Br.J.Pharmacol_137_162
Author(s) : Shimomura M , Okuda H , Matsuda K , Komai K , Akamatsu M , Sattelle DB
Ref : British Journal of Pharmacology , 137 :162 , 2002
Abstract : 1. Neonicotinoid insecticides are agonists of insect nicotinic acetylcholine receptors (AChRs) and show selective toxicity for insects over vertebrates. To elucidate the molecular basis of the selectivity, amino acid residues influencing neonicotinoid sensitivity were investigated by site-directed mutagenesis of the chicken alpha7 nicotinic AChR subunit, based on the crystal structure of an ACh binding protein (AChBP). 2. In the ligand binding site of AChBP, Q55 in loop D is close to Y164 in loop F that corresponds to G189 of the alpha7 nicotinic receptor. Since Q55 of AChBP is preserved as Q79 in the alpha7 nicotinic receptor and the G189D and G189E mutations have been found to reduce the neonicotinoid sensitivity, we investigated effects of Q79E, Q79K and Q79R mutations on the neonicotinoid sensitivity of the alpha7 receptor expressed in Xenopus laevis oocytes to evaluate contributions of the glutamine residue to nicotinic AChR-neonicotinoid interactions. 3. The Q79E mutation markedly reduced neonicotinoid sensitivity of the alpha7 nicotinic AChR whereas the Q79K and Q79R mutations increased sensitivity, suggesting electronic interactions of the neonicotinoids with the added residues. 4. By contrast, the Q79E mutation scarcely influenced responses of the alpha7 nicotinic receptor to ACh, (-)-nicotine and desnitro-imidacloprid (DN-IMI), an imidacloprid derivative lacking the nitro group, whereas the Q79K and Q79R mutations reduced the sensitivity to these ligands. The results indicate that the glutamine residue of the alpha7 nicotinic receptor is likely to be located close to the nitro group of the insecticides in the nicotinic receptor-insecticide complex.
ESTHER : Shimomura_2002_Br.J.Pharmacol_137_162
PubMedSearch : Shimomura_2002_Br.J.Pharmacol_137_162
PubMedID: 12208772

Title : Novel putative nicotinic acetylcholine receptor subunit genes, Dalpha5, Dalpha6 and Dalpha7, in Drosophila melanogaster identify a new and highly conserved target of adenosine deaminase acting on RNA-mediated A-to-I pre-mRNA editing - Grauso_2002_Genetics_160_1519
Author(s) : Grauso M , Reenan RA , Culetto E , Sattelle DB
Ref : Genetics , 160 :1519 , 2002
Abstract : Genome analysis of the fruit fly Drosophila melanogaster reveals three new ligand-gated ion channel subunits with the characteristic YXCC motif found only in alpha-type nicotinic acetylcholine receptor subunits. The subunits are designated Dalpha5, Dalpha6, and Dalpha7. Cloning of the Dalpha5 embryonic cDNAs reveals an atypically large N terminus, part of which is without identifiable sequence motifs and is specified by two polymorphic alleles. Embryonic clones from Dalpha6 contain multiple variant transcripts arising from alternative splicing as well as A-to-I pre-mRNA editing. Alternative splicing in Dalpha6 involves exons encoding nAChR functional domains. The Dalpha6 transcript is a target of the Drosophila adenosine deaminase acting on RNA (dADAR). This is the first case for any organism where a nAChR gene is the target of mRNA editing. Seven adenosines could be modified in the extracellular ligand-binding region of Dalpha6, four of which are also edited in the Dalpha6 ortholog in the tobacco budworm Heliothis virescens. The conservation of an editing site between the insect orders Diptera and Lepidoptera makes nAChR editing the most evolutionarily conserved invertebrate RNA editing site so far described. These findings add to our understanding of nAChR subunit diversity, which is increased and regulated by mechanisms acting at the genomic and mRNA levels.
ESTHER : Grauso_2002_Genetics_160_1519
PubMedSearch : Grauso_2002_Genetics_160_1519
PubMedID: 11973307

Title : Indoxacarb, an oxadiazine insecticide, blocks insect neuronal sodium channels - Lapied_2001_Br.J.Pharmacol_132_587
Author(s) : Lapied B , Grolleau F , Sattelle DB
Ref : British Journal of Pharmacology , 132 :587 , 2001
Abstract : 1. Decarbomethoxyllated JW062 (DCJW), the active component of a new oxadiazine insecticide DPX-JW062 (Indoxacarb), was tested on action potentials and the inward sodium current recorded from short-term cultured dorsal unpaired median neurones of the cockroach Periplaneta americana. 2. Under whole-cell current-clamp conditions, 100 nM DCJW reduced the amplitude of action potentials and induced a large hyperpolarization of the resting membrane potential associated with a 41% increase in input resistance. 3. In voltage-clamp, DCJW resulted in a dose-dependent inhibition (IC(50) 28 nM) of the peak sodium current. Based on IC(50) values, the effect of DCJW was about 10 fold less potent than tetrodotoxin (TTX) but 1000 fold more potent than the local anaesthetic lidocaine. DCJW (100 nM) was without effect on activation properties of the sodium current, reversal potential, voltage dependence of sodium conductance and on both fast and slow steady-state inactivations. 4. TTX (2 nM) resulted in 48% inhibition of the peak inward sodium current. Co-application of TTX (2 nM) with various concentrations of DCJW produced an additional inhibition of the peak inward current, indicating that the blocking actions of DCJW and TTX were distinct. Co-application of lidocaine (IC(50) 30 microM) with various concentrations of DCJW produced a reduction of the apparent potency of DCJW, suggesting that DCJW and lidocaine acted at the same site. 5. DCJW (100 nM) did not affect inward calcium or outward potassium currents. 6. This study describes, for the first time, the action on insect neuronal voltage-dependent sodium channels of Indoxacarb, a new class of insecticides.
ESTHER : Lapied_2001_Br.J.Pharmacol_132_587
PubMedSearch : Lapied_2001_Br.J.Pharmacol_132_587
PubMedID: 11159709

Title : Neonicotinoids: insecticides acting on insect nicotinic acetylcholine receptors - Matsuda_2001_Trends.Pharmacol.Sci_22_573
Author(s) : Matsuda K , Buckingham SD , Kleier D , Rauh JJ , Grauso M , Sattelle DB
Ref : Trends in Pharmacological Sciences , 22 :573 , 2001
Abstract : Imidacloprid is increasingly used worldwide as an insecticide. It is an agonist at nicotinic acetylcholine receptors (nAChRs) and shows selective toxicity for insects over vertebrates. Recent studies using binding assays, molecular biology and electrophysiology suggest that both alpha- and non-alpha-subunits of nAChRs contribute to interactions of these receptors with imidacloprid. Electrostatic interactions of the nitroimine group and bridgehead nitrogen in imidacloprid with particular nAChR amino acid residues are likely to have key roles in determining the selective toxicity of imidacloprid. Chemical calculation of atomic charges of the insecticide molecule and a site-directed mutagenesis study support this hypothesis.
ESTHER : Matsuda_2001_Trends.Pharmacol.Sci_22_573
PubMedSearch : Matsuda_2001_Trends.Pharmacol.Sci_22_573
PubMedID: 11698101

Title : Insecticidal and neural activities of candidate photoaffinity probes for neonicotinoid binding sites - Matsuda_2001_Biosci.Biotechnol.Biochem_65_1534
Author(s) : Matsuda K , Ihara M , Nishimura K , Sattelle DB , Komai K
Ref : Biosci Biotechnol Biochem , 65 :1534 , 2001
Abstract : Photoreactive derivatives of imidacloprid and its nitromethylene analogue were synthesized as candidate photoaffinity probes for identifying the amino acid residues of nicotinic acetylcholine receptors (nAChRs) that interact with the neonicotinoid insecticides. When the candidate probes were injected into American cockroaches, the nerve cord neural activity initially increased, then ceased and death of the insect followed. Both the nerve cord and toxicity were enhanced by changing the photoreactive substituent from the para position to the meta position on the spacer benzyl moiety. When tested on a Drosophila SAD/chicken beta2 hybrid, recombinant nAChR expressed in Xenopus oocytes, the nitromethylene candidate probes showed agonist activity similar to that previously observed for imidacloprid.
ESTHER : Matsuda_2001_Biosci.Biotechnol.Biochem_65_1534
PubMedSearch : Matsuda_2001_Biosci.Biotechnol.Biochem_65_1534
PubMedID: 11515536

Title : Role of loop D of the alpha7 nicotinic acetylcholine receptor in its interaction with the insecticide imidacloprid and related neonicotinoids - Matsuda_2000_Br.J.Pharmacol_130_981
Author(s) : Matsuda K , Shimomura M , Kondo Y , Ihara M , Hashigami K , Yoshida N , Raymond V , Mongan NP , Freeman JC , Komai K , Sattelle DB
Ref : British Journal of Pharmacology , 130 :981 , 2000
Abstract : 1. The nitroguanidine insecticide imidacloprid along with a second generation of related compounds including nitenpyram, all nicotinic acetylcholine (ACh) receptor ligands, are used increasingly in many countries. Site-directed mutagenesis and heterologous expression in Xenopus laevis oocytes have been deployed to investigate mutants (G189D and G189E) of the chicken alpha7 homomer-forming nicotinic receptor subunit which are predicted to enhance the negative charge at the negative subsite (loop D) of the ACh binding site. 2. Xenopus oocytes expressing wild-type alpha7 nicotinic receptors respond to imidacloprid with rapid inward currents. Imidacloprid and nitenpyram are partial agonists, whereas ACh, (-)-nicotine and (+)-epibatidine are full agonists. 3. Compared to wild-type alpha7, the mutant G189D and G189E receptors are much less sensitive to the insecticides, whereas their sensitivity to (-)-nicotine, ACh and (+)-epibatidine is only slightly reduced. In contrast, G189N and G189Q mutants are sensitive not only to ACh, (-)-nicotine and (+)-epibatidine, but also to the two insecticides. Thus reduction of the insecticide-sensitivity by the mutations G189D and G189E are attributed to an increase in negativity of loop D. Desnitro-imidacloprid (DN-IMI), an imidacloprid derivative lacking the nitro group is a potent agonist on the G189D and G189E mutants suggesting an important role of loop D in nicotinic receptor interactions with the nitro group of nitroguanidine insecticides.
ESTHER : Matsuda_2000_Br.J.Pharmacol_130_981
PubMedSearch : Matsuda_2000_Br.J.Pharmacol_130_981
PubMedID: 10882381

Title : Symposium overview: mechanism of action of nicotine on neuronal acetylcholine receptors, from molecule to behavior - Narahashi_2000_Toxicol.Sci_57_193
Author(s) : Narahashi T , Fenster CP , Quick MW , Lester RA , Marszalec W , Aistrup GL , Sattelle DB , Martin BR , Levin ED
Ref : Toxicol Sci , 57 :193 , 2000
Abstract : Nicotine has long been known to interact with nicotinic acetylcholine (ACh) receptors since Langley used it extensively to chart sympathetic ganglia a century ago. It has also been used as an effective insecticide. However, it was not until the 1990s that the significance of nicotine was increasingly recognized from the toxicological, pharmacological, and environmental points of view. This is partly because studies of neuronal nicotinic ACh receptors are rapidly emerging from orphan status, fueled by several lines of research. Since Alzheimer's disease is known to be associated with down-regulation of cholinergic activity in the brain, a variety of nicotine derivatives are being tested and developed for treatment of the disease. Public awareness of the adverse effects of nicotine has reached the highest level recently. Since insect resistance to insecticides is one of the most serious issues in the pest-control arena, it is an urgent requirement to develop new insecticides that act on target sites not shared by the existing insecticides. The neuronal nicotinic ACh receptor is one of them, and new nicotinoids are being developed. Thus, the time is ripe to discuss the mechanism of action of nicotine from a variety of angles, including the molecular, physiological, and behavioral points of view. This Symposium covered a wide area of nicotine studies: genetic, genomic, and functional aspects of nicotinic ACh receptors were studied, as related to anthelmintics and insecticides; interactions between ethanol and nicotine out the ACh receptor were analyzed, in an attempt to explain the well-known heavy drinker-heavy smoker correlation; the mechanisms that underlie the desensitization of ACh receptors were studied as related to nicotine action; selective pharmacological profiles of nicotine, and descriptions of some derivatives were described; and chronic nicotine infusion effects on memory were examined using animal models.
ESTHER : Narahashi_2000_Toxicol.Sci_57_193
PubMedSearch : Narahashi_2000_Toxicol.Sci_57_193
PubMedID: 11006350

Title : A role for Caenorhabditis elegans in understanding the function and interactions of human disease genes - Culetto_2000_Hum.Mol.Genet_9_869
Author(s) : Culetto E , Sattelle DB
Ref : Hum Mol Genet , 9 :869 , 2000
Abstract : A growing number of medical research teams have begun to explore the experimental advantages of using a genetic animal model, the nematode worm Caenorhabditis elegans, with a view to enhancing our understanding of genes underlying human congenital disorders. In this study, we have compared sequences of positionally cloned human disease genes with the C.elegans database of predicted genes. Drawing on examples from spinal muscular atrophy, polycystic kidney disease, muscular dystrophy and Alzheimer's disease, we illustrate how data from C.elegans can yield new insights into the function and interactions of human disease genes.
ESTHER : Culetto_2000_Hum.Mol.Genet_9_869
PubMedSearch : Culetto_2000_Hum.Mol.Genet_9_869
PubMedID: 10767309

Title : Anthelmintic actions on homomer-forming nicotinic acetylcholine receptor subunits: chicken alpha7 and ACR-16 from the nematode Caenorhabditis elegans - Raymond_2000_Neurosci_101_785
Author(s) : Raymond V , Mongan NP , Sattelle DB
Ref : Neuroscience , 101 :785 , 2000
Abstract : Two homomer-forming nicotinic acetylcholine receptor subunits with 47% identity in their amino acid sequences were employed to compare the actions of cholinergic anthelmintics and ivermectin on expressed vertebrate and nematode nicotinic receptors of known molecular composition. Voltage-clamp electrophysiology was used to study recombinant nicotinic receptors expressed in Xenopus laevis oocytes following nuclear injection of cDNA encoding either chicken alpha7 or Caenorhabditis elegans ACR-16 (Ce21) subunits. Butamisole, morantel and metyridine were without agonist actions on either alpha7 or ACR-16 nicotinic receptors in the range 10nM-1mM. However, butamisole (pIC(50)=4.9 for both alpha7 and ACR-16) and morantel (pIC(50)=5.6 for alpha7 and 5.7 for ACR-16) antagonized responses of both alpha7 and ACR-16 receptors to acetylcholine. Metyridine (1mM) did not affect responses to acetylcholine of either receptor. Oxantel was without agonist actions on ACR-16, but was an acetylcholine antagonist (pIC(50)=5.4). In contrast, it was found to have low efficacy agonist action (pEC(50)=4.4) on alpha7 at concentrations in the range 10-300microM. In agreement with a previous study, ivermectin (30microM), an agonist of L-glutamate-gated chloride channels, enhanced the amplitude of responses to acetylcholine of alpha7 nicotinic receptors. However, this same concentration of ivermectin (30microM) did not potentiate the acetylcholine-induced responses of ACR-16, but rather resulted in a slight attenuation. We conclude that oxantel and ivermectin have identified new pharmacological differences between the chicken alpha7 nicotinic receptor and its C. elegans homologue ACR-16.
ESTHER : Raymond_2000_Neurosci_101_785
PubMedSearch : Raymond_2000_Neurosci_101_785
PubMedID: 11113327

Title : Cultured insect mushroom body neurons express functional receptors for acetylcholine, GABA, glutamate, octopamine, and dopamine - Cayre_1999_J.Neurophysiol_81_1
Author(s) : Cayre M , Buckingham SD , Yagodin S , Sattelle DB
Ref : Journal of Neurophysiology , 81 :1 , 1999
Abstract : Fluorescence calcium imaging with fura-2 and whole cell, patch-clamp electrophysiology was applied to cultured Kenyon cells (interneurons) isolated from the mushroom bodies of adult crickets (Acheta domesticus) to demonstrate the presence of functional neurotransmitter receptors. In all cells investigated, 5 microM acetylcholine (ACh, n = 52) evoked an increase in intracellular free calcium ([Ca2+]i). Similar effects were observed in response to 10 microM nicotine. The ACh response was insensitive to atropine (50 microM) but was reduced by mecamylamine (50 microM) and alpha-bungarotoxin (alpha-bgt, 10 microM). ACh-induced inward ion currents (n = 28, EACh approximately 0 mV) were also blocked by 1 microM mecamylamine and by 1 microM alpha-bgt. Nicotine-induced inward currents desensitized more rapidly than ACh responses. Thus functional alpha-bgt-sensitive nicotinic ACh receptors are abundant on all Kenyon cells tested, and their activation leads to an increase in [Ca2+]i. gamma-Aminobutyric acid (GABA, 100 microM) triggered a sustained decrease in [Ca2+]i. Similar responses were seen with a GABAA agonist, muscimol (100 microM), and a GABAB agonist, 3-APPA (1 mM), suggesting that more than one type of GABA receptor can affect [Ca2+]i. This action of GABA was not observed when the extracellular KCl concentration was lowered. All cells tested (n = 26) with patch-clamp electrophysiology showed picrotoxinin (PTX)-sensitive, GABA-induced (30-100 microM) currents with a chloride-sensitive reversal potential. Thus, an ionotropic PTX-sensitive GABA receptor was found on all Kenyon cells tested. Most (61%) of the 54 cells studied responded to -glutamate (100 microM) application either with a biphasic increase in [Ca2+]i or with a single, delayed, sustained [Ca2+]i increase. Nearly all cells tested (95%, n = 19) responded to (100 microM) -glutamate with rapidly desensitizing, inward currents that reversed at approximately -30 mV. Dopamine (100 microM) elicited either a rapid or a delayed increase in [Ca2+]i in 63% of the 26 cells tested. The time course of these responses varied greatly among cells. Dopamine failed to elicit currents in patch-clamped cells (n = 4). A brief decrease in [Ca2+]i was induced by octopamine (100 microM) in approximately 54% of the cells tested (n = 35). However, when extracellular CaCl2 was lowered, octopamine triggered a substantial increase in [Ca2+]i in 35% of the cells tested (n = 26). No octopamine-elicited currents were detected in patched-clamped cells (n = 10).
ESTHER : Cayre_1999_J.Neurophysiol_81_1
PubMedSearch : Cayre_1999_J.Neurophysiol_81_1
PubMedID: 9914262

Title : Effects of the alpha subunit on imidacloprid sensitivity of recombinant nicotinic acetylcholine receptors - Matsuda_1998_Br.J.Pharmacol_123_518
Author(s) : Matsuda K , Buckingham SD , Freeman JC , Squire MD , Baylis HA , Sattelle DB
Ref : British Journal of Pharmacology , 123 :518 , 1998
Abstract : 1. Imidacloprid is a new insecticide with selective toxicity for insects over vertebrates. Recombinant (alpha4beta2) chicken neuronal nicotinic acetylcholine receptors (AChRs) and a hybrid nicotinic AChR formed by co-expression of a Drosophila melanogaster neuronal alpha subunit (SAD) with the chicken beta2 subunit were heterologously expressed in Xenopus oocytes by nuclear injection of cDNAs. The agonist actions of imidacloprid and other nicotinic AChR ligands ((+)-epibatidine, (-)-nicotine and acetylcholine) were compared on both recombinant nicotinic AChRs by use of two-electrode, voltage-clamp electrophysiology. 2. Imidacloprid alone of the 4 agonists behaved as a partial agonist on the alpha4beta2 receptor; (+)-epibatidine, (-)-nicotine and acetylcholine were all full, or near full, agonists. Imidacloprid was also a partial agonist of the hybrid Drosophila SAD chicken beta2 receptor, as was (-)-nicotine, whereas (+)-epibatidine and acetylcholine were full agonists. 3. The EC50 of imidacloprid was decreased by replacing the chicken alpha4 subunit with the Drosophila SAD alpha subunit. This alpha subunit substitution also resulted in an increase in the EC50 for (+)-epibatidine, (-)-nicotine and acetylcholine. Thus, the Drosophila (SAD) alpha subunit contributes to the greater apparent affinity of imidacloprid for recombinant insect/vertebrate nicotinic AChRs. 4. Imidacloprid acted as a weak antagonist of ACh-mediated responses mediated by SADbeta2 hybrid receptors and as a weak potentiator of ACh responses mediated by alpha4beta2 receptors. This suggests that imidacloprid has complex effects upon these recombinant receptors, determined at least in part by the alpha subunit.
ESTHER : Matsuda_1998_Br.J.Pharmacol_123_518
PubMedSearch : Matsuda_1998_Br.J.Pharmacol_123_518
PubMedID: 9504393

Title : Thapsigargin and receptor-mediated activation of Drosophila TRPL channels stably expressed in a Drosophila S2 cell line - Yagodin_1998_Cell.Calcium_23_219
Author(s) : Yagodin S , Hardie RC , Lansdell SJ , Millar NS , Mason WT , Sattelle DB
Ref : Cell Calcium , 23 :219 , 1998
Abstract : The Drosophila melanogaster genes, transient receptor potential (trp) and transient receptor potential-like (trpl) encode putative plasma membrane cation channels TRP and TRPL, respectively. We have stably co-expressed Drosophila TRPL with a Drosophila muscarinic acetylcholine receptor (DM1) in a Drosophila cell line (S2 cells). Basal Ca2+ levels measured using Fura-2/AM in unstimulated S2-DM1-TRPL cells were low and indistinguishable from untransfected cells, indicating that the TRPL channels were not constitutively active in this expression system. Activation of DM1 receptor in S2-DM1-TRPL cells by 100 microM carbamylcholine induced Ca2+ release from an intracellular Ca2+ pool followed by a Gd(3+)-insensitive Ca2+ influx. Pretreatment of S2-DM1-TRPL cells with 10 microM atropine abolished Gd(3+)-insensitive Ca2+ influx triggered by carbamylcholine, but the response was not blocked by prior incubation with pertussis toxin. TRPL channels could also be reliably activated by bath application of 1 microM thapsigargin for 10 min or 100 nM thapsigargin for 60 min in Ca(2+)-free solution. In some cells, TRPL channels activated by thapsigargin could further be activated by carbamylcholine. The findings suggest that, when stably expressed in the S2 cell line, TRPL may be regulated by two distinct mechanisms: (i) store depletion; and (ii) stimulation of DM1 receptor via pertussis-toxin insensitive G-protein (or the subsequent activation of PLC), but without further requirement for Ca2+ release.
ESTHER : Yagodin_1998_Cell.Calcium_23_219
PubMedSearch : Yagodin_1998_Cell.Calcium_23_219
PubMedID: 9681185

Title : Antagonist profile and molecular dynamic simulation of a Drosophila melanogaster muscarinic acetylcholine receptor - Reaper_1998_Receptors.Channels_5_331
Author(s) : Reaper CM , Fanelli F , Buckingham SD , Millar NS , Sattelle DB
Ref : Receptors Channels , 5 :331 , 1998
Abstract : A stably-transfected, Drosophila cell line (S2-DMl-1) expressing the Drosophila DMl muscarinic acetylcholine receptor (mAChR) exhibits high-affinity, saturable, specific binding of the radiolabelled muscarinic antagonist [3H]-N-methyl scopolamine ([3H]-NMS) with an equilibrium dissociation constant (Kd) of 0.67 +/- 0.02 and a Bmax of 1.53 +/- 0.3 pmol/mg protein. Displacement of [3H]-NMS by mAChR antagonists results in the pharmacological profile: 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) > hexahydrosiladifenidol > p-fluorohexahydrosiladifenidol > nitrocaramiphen > pirenzepine > methoctramine > AFDX-116. This antagonist profile most closely resembles that of the vertebrate M3 mAChR subtype. In this study, however, we have demonstrated that the antagonist profile of DM1 is distinct from those of vertebrate mAChR subtypes. Molecular dynamic simulations of the Drosophila muscarinic receptor are presented in the free, carbamylcholine-bound and NMS-bound forms. Theoretical, quantitative structure-activity relationship models have been developed; a good correlation is observed between the interaction energies of the minimized ligand-receptor complexes and the pharmacological affinities of the antagonists tested.
ESTHER : Reaper_1998_Receptors.Channels_5_331
PubMedSearch : Reaper_1998_Receptors.Channels_5_331
PubMedID: 9826910

Title : An extensive and diverse gene family of nicotinic acetylcholine receptor alpha subunits in Caenorhabditis elegans - Mongan_1998_Receptors.Channels_6_213
Author(s) : Mongan NP , Baylis HA , Adcock C , Smith GR , Sansom MS , Sattelle DB
Ref : Receptors Channels , 6 :213 , 1998
Abstract : Using reverse transcription-polymerase chain reactions the transcription of eight novel candidate nicotinic acetylcholine receptor (nAChR) alpha subunit genes has been demonstrated in the nematode Caenorhabditis elegans. Together with five other alpha subunit genes described elsewhere by ourselves (unc-38) and other workers (deg-3, acr-4, Ce21 and acr-6), this is now the largest known family of nAChR alpha subunit genes in a single species. By homology we have identified four groups of alpha subunits: DEG-3-like; ACR-16[Ce21]-like; UNC-38-like and ACR-8-like. Five C. elegans nAChR alpha subunits contain a modification in loop C of the ACh binding site in which the normally conserved Tyr-x-Cys-Cys, is replaced by a distinct motif (Tyr-x-x-Cys-Cys). Variation is also found in the channel lining M2 regions, including the replacement in four subunits of the highly conserved leucine at the 9' position by valine and most notably, the replacement in all ACR-8-like subunits of the highly conserved glutamic acid at the -1' position by histidine. Restrained molecular dynamics simulations have been used to generate homo-pentameric M2 helix bundle models for alpha subunits and possible functional implications examined. The calculated electrostatic potential energy profile for the M2 region of ACR-8 differs strikingly from that of ACR-16[Ce21] largely due to the presence of histidine at the -1' position, suggesting a possible perturbation of nAChR channel action permeability in the presence of this subunit type.
ESTHER : Mongan_1998_Receptors.Channels_6_213
PubMedSearch : Mongan_1998_Receptors.Channels_6_213
PubMedID: 10100329

Title : Functional characterization of a mutated chicken alpha7 nicotinic acetylcholine receptor subunit with a leucine residue inserted in transmembrane domain 2 - Buckingham_1998_Br.J.Pharmacol_124_747
Author(s) : Buckingham SD , Adcock C , Sansom MS , Sattelle DB , Baylis HA
Ref : British Journal of Pharmacology , 124 :747 , 1998
Abstract : 1. Site-directed mutagenesis was used to create an altered form of the chicken alpha7 nicotinic acetylcholine (ACh) receptor subunit (alpha7x61) in which a leucine residue was inserted between residues Leu9' and Ser10' in transmembrane domain 2. The properties of alpha7x61 receptors are distinct from those of the wild-type receptor. 2. Oocytes expressing wild-type alpha7 receptors responded to 10 microM nicotine with rapid inward currents that desensitized with a time-constant of 710+/-409 ms (mean+/-s.e.mean, n=5). However in alpha7x61 receptors 10 microM nicotine resulted in slower onset inward currents that desensitized with a time-constant of 5684+/-3403 ms (mean+/-s.e.mean, n = 4). No significant difference in the apparent affinity of nicotine or acetylcholine between mutant and wild-type receptors was observed. Dihydro-beta-erythroidine (DHbetaE) acted as an antagonist on both receptors. 3. Molecular modelling of the alpha7x61 receptor channel pore formed by a bundle of M2 alpha-helices suggested that three of the channel lining residues would be altered by the leucine insertion i.e.; Ser10 would be replaced by the leucine insertion, Val13' and Phe14' would be replaced, by Thr and Val, respectively. 4 When present in the LEV-1 nicotinic ACh receptor subunit from Caenorhabditis elegans the same alteration conferred resistance to levamisole anthelmintic drug. Levamisole blocked responses to nicotine of wild-type and alpha7x61 receptors. However, block was more dependent on membrane potential for the alpha7x61 receptors. 5. We conclude that the leucine insertion in transmembrane domain 2 has the unusual effect of slowing desensitization without altering apparent agonist affinity.
ESTHER : Buckingham_1998_Br.J.Pharmacol_124_747
PubMedSearch : Buckingham_1998_Br.J.Pharmacol_124_747
PubMedID: 9690867

Title : Temperature-sensitive expression of Drosophila neuronal nicotinic acetylcholine receptors - Lansdell_1997_J.Neurochem_68_1812
Author(s) : Lansdell SJ , Schmitt B , Betz H , Sattelle DB , Millar NS
Ref : Journal of Neurochemistry , 68 :1812 , 1997
Abstract : Heterologous expression of cloned Drosophila nicotinic acetylcholine receptor (nAChR) subunits indicates that these proteins misfold when expressed in mammalian cell lines at 37 degrees C. This misfolding can, however, be overcome either by growing transfected mammalian cells at lower temperatures or by the expression of Drosophila nAChR subunits in a Drosophila cell line. Whereas the Drosophila nAChR beta subunit (SBD) cDNA, reported previously, lacked part of the SBD coding sequence, here we report the construction and expression of a full-length SBD cDNA. We have examined whether problems in expressing functional Drosophila nAChRs in either Xenopus oocytes or mammalian cell lines can be attributed to an inability of these expression systems to assemble correctly Drosophila nAChRs. Despite expression in what might be considered a more native cellular environment, we have been unable to detect functional nAChRs in a Drosophila cell line unless Drosophila nAChR subunit cDNAs are coexpressed with vertebrate nAChR subunits. Our results indicate that the folding of Drosophila nAChR subunits is temperature-sensitive and strongly suggest that the inability of these Drosophila nAChR subunits to generate functional channels in the absence of vertebrate subunits is due to a requirement for coassembly with as yet unidentified Drosophila nAChR subunits.
ESTHER : Lansdell_1997_J.Neurochem_68_1812
PubMedSearch : Lansdell_1997_J.Neurochem_68_1812
PubMedID: 9109505

Title : Prothoracicotropic hormone-producing neurosecretory cells in the silkworm, Bombyx mori, express a muscarinic acetylcholine receptor - Aizono_1997_Brain.Res_763_131
Author(s) : Aizono Y , Endo Y , Sattelle DB , Shirai Y
Ref : Brain Research , 763 :131 , 1997
Abstract : Using an anti-muscarinic acetylcholine receptor (mAChR) antibody and an anti-prothoracicotropic hormone (PTTH) antibody, double immunofluorescence staining was performed on brain sections of the silkworm, Bombyx mori. Four pairs of dorsolateral neurosecretory cells, along with some intercerebral neurosecretory cells, were immunoreactive to anti-mAChR antibody. Among these immunoreactive cells, two pairs of dorsolateral neurosecretory cells were identified to be PTTH-producing neurosecretory cells. Nerve fibers in the median and paramedian protocerebral areas, and nerve terminals in the corpus allatum also showed immunoreactivity to the anti-mAChR antibody. Some of these nerve terminals expressing mAChRs were overlapped by immunostaining with the anti-PTTH antibody. These results indicated that PTTH-producing neurosecretory cells of Bombyx mori expressed an mAChR, and that muscarinic, cholinergic transmission might directly regulate PTTH release from neurosecretory cells.
ESTHER : Aizono_1997_Brain.Res_763_131
PubMedSearch : Aizono_1997_Brain.Res_763_131
PubMedID: 9272838

Title : Caenorhabditis elegans levamisole resistance genes lev-1, unc-29, and unc-38 encode functional nicotinic acetylcholine receptor subunits - Fleming_1997_J.Neurosci_17_5843
Author(s) : Fleming JT , Squire MD , Barnes TM , Tornoe C , Matsuda K , Ahnn J , Fire A , Sulston JE , Barnard EA , Sattelle DB , Lewis JA
Ref : Journal of Neuroscience , 17 :5843 , 1997
Abstract : We show that three of the eleven genes of the nematode Caenorhabditis elegans that mediate resistance to the nematocide levamisole and to other cholinergic agonists encode nicotinic acetylcholine receptor (nAChR) subunits. unc-38 encodes an alpha subunit while lev-1 and unc-29 encode non-alpha subunits. The nematode nAChR subunits show conservation of many mammalian nAChR sequence features, implying an ancient evolutionary origin of nAChR proteins. Expression in Xenopus oocytes of combinations of these subunits that include the unc-38 alpha subunit results in levamisole-induced currents that are suppressed by the nAChR antagonists mecamylamine, neosurugatoxin, and d-tubocurarine but not alpha-bungarotoxin. The mutant phenotypes reveal that unc-38 and unc-29 subunits are necessary for nAChR function, whereas the lev-1 subunit is not. An UNC-29-GFP fusion shows that UNC-29 is expressed in body and head muscles. Two dominant mutations of lev-1 result in a single amino acid substitution or addition in or near transmembrane domain 2, a region important to ion channel conductance and desensitization. The identification of viable nAChR mutants in C. elegans provides an advantageous system in which receptor expression and synaptic targeting can be manipulated and studied in vivo.
ESTHER : Fleming_1997_J.Neurosci_17_5843
PubMedSearch : Fleming_1997_J.Neurosci_17_5843
PubMedID: 9221782

Title : ACR-3, a Caenorhabditis elegans nicotinic acetylcholine receptor subunit. Molecular cloning and functional expression - Baylis_1997_Receptors.Channels_5_149
Author(s) : Baylis HA , Matsuda K , Squire MD , Fleming JT , Harvey RJ , Darlison MG , Barnard EA , Sattelle DB
Ref : Receptors Channels , 5 :149 , 1997
Abstract : The molecular cloning and functional co-expression of a novel nicotinic acetylcholine receptor (nAChR) non-alpha subunit gene, acr-3, is described. Previously we determined the sequence and demonstrated the functional co-expression of acr-2, a nAChR non-alpha subunit gene from Caenorhabditis elegans. Analysis of the acr-2 genomic DNA revealed the existence of another potential nAChR subunit gene, acr-3, in the same orientation, only 281 bp downstream of acr-2. A cDNA containing the entire acr-3 coding sequence was isolated by RT-PCR and sequenced. The predicted protein contains the conserved features typical of nAChR non-alpha subunits and most closely resembles other invertebrate nAChR non-alpha polypeptides. Unusually, the highly conserved glycine residue (equivalent to residue 240 in the Torpedo alpha subunit) upstream of transmembrane domain 2 (m2) is replaced by a serine residue in ACR-3. When acr-3 cDNA was injected alone into Xenopus oocytes no levamisole-gated channel activity was observed. However when co-expressed with a C. elegans alpha subunit (UNC-38), ACR-3 contributed to the formation of levamisole-gated channels. The response of this hetero-oligomer to levamisole (100 microM) was reduced by the nAChR antagonists mecamylamine (1 microM) and d-tubocurarine (10 microM).
ESTHER : Baylis_1997_Receptors.Channels_5_149
PubMedSearch : Baylis_1997_Receptors.Channels_5_149
PubMedID: 9606719

Title : Lophotoxin-insensitive nematode nicotinic acetylcholine receptors - Tornoe_1996_J.Exp.Biol_199_2161
Author(s) : Tornoe C , Holden-Dye L , Garland C , Abramson SN , Fleming JT , Sattelle DB
Ref : J Exp Biol , 199 :2161 , 1996
Abstract : Nematode nicotinic acetylcholine receptors (nAChRs) are molecular targets of several anthelmintic drugs. Studies to date on Caenorhabditis elegans and Ascaris suum have demonstrated atypical pharmacology with respect to nAChR antagonists, including the finding that kappa-bungarotoxin is a more effective antagonist than alpha-bungarotoxin on Ascaris muscle nAChRs. Lophotoxin and its naturally occurring analogue bipinnatin B block all vertebrate and invertebrate nAChRs so far examined. In the present study, the effects on nematode nAChRs of bipinnatin B have been examined. The Ascaris suum muscle cell nAChR was found to be insensitive to 30 mumol l-1 bipinnatin B, a concentration that is highly effective on other nAChRs. To our knowledge, this is the first demonstration of a nAChR that is insensitive to one of the lophotoxins. Xenopus laevis oocytes injected with C. elegans polyadenylated, poly(A+), mRNA also expressed bipinnatin-B-insensitive levamisole responses, which were, however, blocked by the nAChR antagonist mecamylamine (10 mumol l-1). In contrast to the findings for nematode receptors, bipinnatin B (30 mumol l-1) was effective in blocking mouse muscle nAChRs expressed in Xenopus laevis oocytes and native insect nAChRs. A possible explanation for insensitivity of certain nematode nAChRs to lophotoxins is advanced based on the sequence of an alpha-like C. elegans nAChR subunit in which tyrosine-190 (numbering based on the Torpedo californica sequence), a residue known to be critical for lophotoxin binding in vertebrate nAChRs, is replaced by a proline residue.
ESTHER : Tornoe_1996_J.Exp.Biol_199_2161
PubMedSearch : Tornoe_1996_J.Exp.Biol_199_2161
PubMedID: 8896363

Title : Nicotine increases [Ca2+]i and regulates electrical activity in insect neurosecretory cells (DUM neurons) via an acetylcholine receptor with 'mixed' nicotinic-muscarinic pharmacology - Grolleau_1996_Neurosci.Lett_220_142
Author(s) : Grolleau F , Lapied B , Buckingham SD , Mason WT , Sattelle DB
Ref : Neuroscience Letters , 220 :142 , 1996
Abstract : An increase in intracellular free calcium concentration ([Ca2+]i) was observed following the application of nicotine to isolated adult dorsal unpaired median (DUM) neurons of the cockroach (Periplaneta americana) terminal abdominal ganglion (TAG) using Fura-2 fluorescence measurements. Bath-applied nicotine (1 mM) induced a transient increase in [Ca2+]i. Calcium responses to bath-applied nicotine were blocked completely by alpha-bungarotoxin (100 nM) and were reduced by 50% in the presence of pirenzepine (1 microM). The sensitivity of the response to both nicotinic and muscarinic antagonists suggested that it was mediated by an acetylcholine receptor with 'mixed' pharmacology. In whole cell current-clamp experiments, nicotine reduced the frequency of evoked action potentials by decreasing the slope of the predepolarization in the last two-thirds of the pacemaker potential. Voltage-clamp studies revealed that nicotine modified the inactivation properties of the maintained low-voltage-activated (LVA) calcium current increasing the rate of relaxation of this current and transforming a U-shaped voltage dependence of inactivation into a monotonic relationship to voltage. These effects were blocked when isolated DUM neurons were pretreated with 0.5 microM alpha-bungarotoxin. Our findings suggested a novel calcium-dependent regulation of firing behavior in TAG DUM neurons following activation of an acetylcholine receptor with 'mixed' pharmacology, resulting in a rise in [Ca2+]i which reduces firing frequency by modulating a maintained LVA calcium current responsible for the action potential predepolarization.
ESTHER : Grolleau_1996_Neurosci.Lett_220_142
PubMedSearch : Grolleau_1996_Neurosci.Lett_220_142
PubMedID: 8981493

Title : Wild-type and insecticide-resistant homo-oligomeric GABA receptors of Drosophila melanogaster stably expressed in a Drosophila cell line - Buckingham_1996_Neuropharmacol_35_1393
Author(s) : Buckingham SD , Matsuda K , Hosie AM , Baylis HA , Squire MD , Lansdell SJ , Millar NS , Sattelle DB
Ref : Neuropharmacology , 35 :1393 , 1996
Abstract : RDL is an ionotropic GABA receptor subunit, a product of the Rdl gene, originally identified in the Maryland strain of Drosophila melanogaster. Here, we report the generation of a Drosophila melanogaster cell line (S2-RDLA302S) stably expressing a mutated, dieldrin-resistant (A302S) form of RDL. The properties of this dieldrin-resistant, homo-oligomeric receptor have been compared with those of the stably expressed, wild-type form (S2-RDL). Using these stable lines, a striking reduction in sensitivity to both picrotoxinin and dieldrin was observed for responses to GABA of S2-RDLA302S compared to S2-RDL. To determine if these stable insect cell lines generate results similar to those obtained by transient expression in Xenopus laevis oocytes, we have examined the actions of two widely used convulsants, EBOB and TBPS, and a recently developed convulsant BIDN, on RDL-mediated GABA responses in the two expression systems. In both oocytes and S2 cells, the three convulsants suppressed the amplitude of responses to GABA. Thus, in accord with earlier work on agonist and allosteric sites, the S2-RDL cell line is found to yield similar pharmacological results to those obtained in transient expression studies. Stable cell lines are now available expressing susceptible and resistant forms of an ionotropic receptor by GABAergic insecticides.
ESTHER : Buckingham_1996_Neuropharmacol_35_1393
PubMedSearch : Buckingham_1996_Neuropharmacol_35_1393
PubMedID: 9014156

Title : Molecular cloning and in vitro expression of C. elegans and parasitic nematode ionotropic receptors - Fleming_1996_Parasitol_113 Suppl_S175
Author(s) : Fleming JT , Baylis HA , Sattelle DB , Lewis JA
Ref : Parasitology , 113 Suppl :S175 , 1996
Abstract : The free living nematode, C. elegans is understood at a level of detail equalled by few other organisms, and much of the cell biology and sequence information is proving of considerable utility in the study of parasitic nematodes. Already, C. elegans provides a convenient vehicle for investigating anthelmintic drug action and resistance mechanisms. Among the ionotropic receptors, with their important roles in the behaviour and development of the organism, are targets for anthelmintics. The subunits of nicotinic acetylcholine receptors of C. elegans form a large and diverse multigene family. Members of this family are among the 11 genes associated with resistance to the anthelmintic drug levamisole.
ESTHER : Fleming_1996_Parasitol_113 Suppl_S175
PubMedSearch : Fleming_1996_Parasitol_113 Suppl_S175
PubMedID: 9051934

Title : Genetic analysis of cholinergic nerve terminal function in invertebrates - Baylis_1996_J.Neurocytol_25_747
Author(s) : Baylis HA , Sattelle DB , Lane NJ
Ref : Journal of Neurocytology , 25 :747 , 1996
Abstract : Genetic analysis of nerve terminal function is proving fruitful and studies on invertebrates are making a substantial impact. In this survey, particular emphasis has been placed on cholinergic chemical synaptic transmission. The advanced genetics of Drosophila melanogaster and Caenorhabditis elegans with their rich diversity of behavioural and biochemical mutants is providing new insights into the functions of key molecular components of synapses. A 'space-invader' mutant of Periplaneta americana permits investigations of competition between neurons during synaptogenesis and its impact on neurotransmitter release. The growing importance of the C. elegans genome as a major research resource is emphasized in this survey.
ESTHER : Baylis_1996_J.Neurocytol_25_747
PubMedSearch : Baylis_1996_J.Neurocytol_25_747
PubMedID: 9023722

Title : Functional expression of a cloned Drosophila muscarinic acetylcholine receptor in a stable Drosophila cell line - Millar_1995_J.Exp.Biol_198_1843
Author(s) : Millar NS , Baylis HA , Reaper C , Bunting R , Mason WT , Sattelle DB
Ref : J Exp Biol , 198 :1843 , 1995
Abstract : A cloned Drosophila muscarinic acetylcholine receptor (mAChR) has been stably expressed in a Drosophila cell line (S2) under the control of an inducible Drosophila metallothionein promoter. A clonal cell line (S2-Dm1-1) has been isolated which, after induction of mAChR expression with CuSO4, exhibits high-affinity, saturable, specific binding of the muscarinic antagonist N-methyl scopolamine (NMS). The apparent molecular mass of the expressed protein, calculated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), is in good agreement with the apparent molecular mass of mAChRs purified from Drosophila brain. Functional expression of the cloned mAChR in this stable cell line has been demonstrated by quantitative fluorescence ratio-imaging of Fura-2-loaded cells. We have observed transient, agonist-induced elevations in intracellular Ca2+ levels which can be completely blocked by atropine, whereas AFDX-116, a muscarinic antagonist which binds preferentially to the vertebrate mAChR M2 subtype, has little effect at 100 mumol l-1. The suitability of this stable Drosophila expression system for the characterization of neurotransmitter receptors is discussed.
ESTHER : Millar_1995_J.Exp.Biol_198_1843
PubMedSearch : Millar_1995_J.Exp.Biol_198_1843
PubMedID: 7595159

Title : Actions of neurotoxins (bungarotoxins, neosurugatoxin and lophotoxins) on insect and nematode nicotinic acetylcholine receptors - Tornoe_1995_Toxicon_33_411
Author(s) : Tornoe C , Bai D , Holden-Dye L , Abramson SN , Sattelle DB
Ref : Toxicon , 33 :411 , 1995
Abstract : Neurotoxins of natural origin have proved to be of considerable value in the isolation and characterization of vertebrate muscle and neuronal nicotinic acetylcholine receptors (nAChRs). To date, they have been used less extensively in studies of invertebrate nAChRs. Here we examine how a variety of neurotoxins (the snake toxins alpha-bungarotoxin, alpha-BGT, and kappa-bungarotoxin, kappa-BGT, the molluscan toxin, neosurugatoxin, and the soft coral toxins, lophotoxin and bipinnatin-B) can be used to characterize nAChRs in an insect, Periplaneta americana, and in a parasitic nematode, Ascaris suum. The agonist profiles of these nAChRs are distinct, but the most striking differences are in the actions of antagonists. Whereas the insect nAChR is blocked by both alpha- and kappa-bungarotoxins, the nematode receptor is only blocked by kappa-BGT. Neosurugatoxin blocks nAChRs in both species, but the lophotoxins which block all nAChRs investigated to date are much less effective on the Ascaris muscle receptor.
ESTHER : Tornoe_1995_Toxicon_33_411
PubMedSearch : Tornoe_1995_Toxicon_33_411
PubMedID: 7570627

Title : Actions of nitromethylenes on an alpha-bungarotoxin-sensitive neuronal nicotinic acetylcholine receptor - Buckingham_1995_Neuropharmacol_34_591
Author(s) : Buckingham SD , Balk ML , Lummis SC , Jewess P , Sattelle DB
Ref : Neuropharmacology , 34 :591 , 1995
Abstract : Nine nitromethylene analogues were tested for their actions on insect neuronal nicotinic acetylcholine receptors (nAChRs). Microelectrode recordings were used to study the actions of nitromethylenes on the cell body of an identified cockroach (Periplaneta americana) motor neurone, the fast coxal depressor (Df) in the metathoracic ganglion. Six nitromethylenes showed potent nAChR agonist actions; others were without nAChR agonist actions. Five nitromethylenes competitively displaced bound [125I]-alpha-bungarotoxin from cockroach nervous system membranes. The rank orders of potency for the compounds determined by their depolarizing actions and their ability to displace [125I]-alpha-bungarotoxin binding were similar. These findings, together with toxicity data obtained on the insects, Nephotettix cinciteps and Nilaparvata lugens, support the hypothesis that insect nAChRs are molecular targets of nitromethylene insecticides. Structure-activity relationships of the nitromethylenes suggest that optimal activity at neuronal nAChRs requires the presence of an electron-withdrawing component in the region of the aryl substituent and an electron-donating component at the 3' position of the imidazolidine ring.
ESTHER : Buckingham_1995_Neuropharmacol_34_591
PubMedSearch : Buckingham_1995_Neuropharmacol_34_591
PubMedID: 7566494

Title : Localization in the nervous system of Drosophila melanogaster of a C-terminus anti-peptide antibody to a cloned Drosophila muscarinic acetylcholine receptor - Harrison_1995_J.Neuroendocrinol_7_347
Author(s) : Harrison JB , Chen HH , Blake AD , Huskisson NS , Barker P , Sattelle DB
Ref : J Neuroendocrinol , 7 :347 , 1995
Abstract : Localization in the nervous system of Drosophila melanogaster of a cloned Drosophila muscarinic acetylcholine receptor (mAChR) was investigated using a polyclonal antiserum raised against a peptide corresponding to the predicted receptor carboxyl terminal domain. Immunocytochemical studies on fly sections indicated that the product of the Dm1 mAChR gene was localized in the antennal lobes and in other regions of the brain and thoracic nervous system. Intense staining in the glomeruli of the antennal lobes, the region of the nervous system containing terminals of antennal olfactory sensory neurones and mechanosensory neurones, indicates possible roles for this mAChR gene product in the processing of olfactory and mechanosensory signals in the fly. The staining of a discrete group of neurosecretory cells in the pars intercerebralis of the brain indicates a possible new role for this mAChR in the regulation of neurosecretion. Very little staining is detected in the thoracic nervous system.
ESTHER : Harrison_1995_J.Neuroendocrinol_7_347
PubMedSearch : Harrison_1995_J.Neuroendocrinol_7_347
PubMedID: 7550280

Title : Molecular cloning and functional co-expression of a Caenorhabditis elegans nicotinic acetylcholine receptor subunit (acr-2) - Squire_1995_Receptors.Channels_3_107
Author(s) : Squire MD , Tornoe C , Baylis HA , Fleming JT , Barnard EA , Sattelle DB
Ref : Receptors Channels , 3 :107 , 1995
Abstract : A number of putative nicotinic acetylcholine receptor subunit clones were isolated by screening a lambda library of Caenorhabditis elegans genomic DNA with a probe derived from the Drosophila melanogaster ard gene (a non-alpha nicotinic acetylcholine receptor subunit clone). Studies on one of these loci, acr-2, are described; acr-2 is located between sup-7 and unc-6 on the X chromosome. A full-length cDNA was isolated and sequenced. The cDNA encodes a putative non-alpha subunit of a nicotinic acetylcholine receptor that shows many of the conserved features of vertebrate and invertebrate non-alpha nicotinic acetylcholine receptor subunits. To investigate the functional expression of the subunit, the corresponding cRNA was produced, in vitro, and micro-injected into Xenopus oocytes. When expressed alone acr-2 shows no levamisole-gated channel activity. When co-expressed with a C. elegans alpha subunit (unc-38), which is itself unable to form functional homo-oligomers, acr-2 contributed to the formation of a functional channel. This is the first functional expression of a nematode nicotinic acetylcholine receptor and supports the interpretation that the differentiation between alpha and non-alpha subunits dates back to the earliest stages of the evolution of the metazoa.
ESTHER : Squire_1995_Receptors.Channels_3_107
PubMedSearch : Squire_1995_Receptors.Channels_3_107
PubMedID: 8581398

Title : Stable expression of a functional homo-oligomeric Drosophila GABA receptor in a Drosophila cell line - Millar_1994_Proc.Biol.Sci_258_307
Author(s) : Millar NS , Buckingham SD , Sattelle DB
Ref : Proc Biol Sci , 258 :307 , 1994
Abstract : A cloned Drosophila gamma-aminobutyric acid GABA receptor subunit (Rdl) has been stably expressed as a functional homo-oligomeric ion channel in a Drosophila cell line. Stably-transfected clonal cell lines which expressed high levels of GABA receptor were identified by specific [3H]-muscimol binding. Expression of functional GABA-gated ion channels in these cell lines was demonstrated by electrophysiological recording. Rapid and pronounced rundown of responses to GABA during whole-cell patch clamp recordings was overcome by the inclusion of EGTA in the pipette solution, indicating a possible role for calcium-dependent processes in the functional regulation of this GABA receptor. Relative agonist potencies of the expressed receptor were found to be in the order GABA = TACA > CACA. We have observed a reversible block of the receptor by the convulsant antagonists, picrotoxinin and EBOB, and by the insecticide fipronil. Potentiation of GABA responses was seen with the anaesthetic steroid 5 alpha-pregnan-3 alpha-ol-20-one. No significant effects (either agonist, antagonist or modulatory) were observed with bicuculline (a vertebrate GABAAR antagonist), benzodiazepines or barbiturates (vertebrate GABAAR modulators), or with glycine agonist of the closely related vertebrate glycine receptors). The suitability of this Drosophila stable expression system for the characterization of receptors and ion channels is discussed.
ESTHER : Millar_1994_Proc.Biol.Sci_258_307
PubMedSearch : Millar_1994_Proc.Biol.Sci_258_307
PubMedID: 7533909

Title : Muscarinic acetylcholine receptors on an identified motor neurone in the cockroach, Periplaneta americana - Bai_1994_Neurosci.Lett_175_161
Author(s) : Bai D , Sattelle DB
Ref : Neuroscience Letters , 175 :161 , 1994
Abstract : Muscarinic acetylcholine receptors (mAChRs) on the cell body of the fast coxal depressor motor neurone (Df) in the metathoracic ganglion of the cockroach Periplaneta americana were investigated using electrophysiological methods. Muscarinic agonists, arecoline and oxotremorine, induced dose-dependent depolarizations on motor neurone Df. McN-A-343, a vertebrate mAChR M1 subtype-selective agonist, failed to induce any responses when tested on the same neurone at concentrations of up to 1.0 x 10(-4) M. The order of effectiveness of a series of muscarinic antagonists on the mAChRs of motor neurone Df is as follows: scopolamine > atropine > pirenzepine. 4-DAMP (1.0 x 10(-5) M) had only a weak blocking effect and AF-DX 116 (1.0 x 10(-5) M) was completely inactive. The pharmacological profile of muscarinic responses on motor neurone Df reveals a novel type of insect mAChR.
ESTHER : Bai_1994_Neurosci.Lett_175_161
PubMedSearch : Bai_1994_Neurosci.Lett_175_161
PubMedID: 7526292

Title : Drosophila nervous system muscarinic acetylcholine receptor: transient functional expression and localization by immunocytochemistry - Blake_1993_Mol.Pharmacol_44_716
Author(s) : Blake AD , Anthony NM , Chen HH , Harrison JB , Nathanson NM , Sattelle DB
Ref : Molecular Pharmacology , 44 :716 , 1993
Abstract : The pharmacological properties of a cloned Drosophila muscarinic acetylcholine receptor (mAChR) were investigated using two independent transient expression systems. The binding characteristics of the expressed receptor were determined using transfected COS-7 cells, whereas the mAChR functional properties were analyzed using nuclearly injected Xenopus oocytes. Competition displacement studies with transfected COS-7 cell membranes showed that N-[3H]methylscopolamine binding was displaced most effectively by atropine, followed by 4-diphenylacetoxy-N-methylpiperidine methiodide, pirenzepine, and AFDX-116. This same order of effectiveness (4-diphenylacetoxy-N-methylpiperidine methiodide > pirenzepine > AFDX-116) was observed in oocytes expressing Dm1 when carbamylcholine-induced currents were inhibited by the same antagonists. Thus, the expressed Drosophila mAChR (Dm1) exhibits a pharmacology that broadly resembles that of the vertebrate M1 and M3 mAChR subtypes. To determine the anatomical localization of the Drosophila mAChR, polyclonal antiserum was raised against a peptide corresponding to the predicted carboxyl-terminal domain of the receptor. Immunocytochemistry on fly sections demonstrated that the mAChR gene product was found in the nervous system and was not seen in skeletal muscle. The most intense staining was localized to the glomeruli of the antennal lobes, an area of the insect brain where first-order synaptic processing of olfactory information occurs.
ESTHER : Blake_1993_Mol.Pharmacol_44_716
PubMedSearch : Blake_1993_Mol.Pharmacol_44_716
PubMedID: 8232221

Title : Acetylcholine receptor\/channel molecules of insects - Leech_1993_EXS_63_81
Author(s) : Leech CA , Sattelle DB
Ref : Exs , 63 :81 , 1993
Abstract : Acetylcholine-gated ion channels of the nicotinic type are abundant in the nervous system of insects. The channels are permeable to Na+, K+ and probably Ca(2+), and unlike most vertebrate neuronal nicotinic acetylcholine receptors the receptor/channel molecule is blocked by alpha-bungarotoxin (alpha-Bgt). Such alpha-Bgt-sensitive receptors are present at synapses and on cell bodies of insect neurones. Single channel recordings have shown the existence of multiple conductances of nAChRs. Studies on several different insect preparations have provided evidence for more than one open state and several closed states of insect nAChRs. Functional insect nAChR channels have now been investigated in situ, following reconstitution of a purified protein in bilayers, and as a result of expressing in Xenopus oocytes messenger RNA encoding receptor subunits.
ESTHER : Leech_1993_EXS_63_81
PubMedSearch : Leech_1993_EXS_63_81
PubMedID: 7678532

Title : Actions of vesamicol on an alpha-bungarotoxin-sensitive neuronal nicotinic acetylcholine receptor - Buckingham_1993_J.Exp.Biol_182_255
Author(s) : Buckingham SD , Lummis SC , Balk ML , Schroeder M , Sattelle DB
Ref : J Exp Biol , 182 :255 , 1993
Abstract : Electrophysiology and binding studies were used to determine the actions of vesamicol [2-(4-phenylpiperidino)cyclohexanol (AH5183)] on an alpha-bungarotoxin-sensitive, neuronal nicotinic acetylcholine receptor in the nervous system of the cockroach, Periplaneta americana. Electrophysiological studies on an identified motor neurone revealed a reversible blocking action of (+/-)-vesamicol on the response to ionophoretically applied acetylcholine with an IC50 value of 8.0 x 10(-6) mol1(-1). The block was weakly voltage-dependent over the membrane potential range of -50 mV to -90 mV, and appeared to be non-competitive. No difference in potency was observed between the resolved stereoisomers. (+/-)-Vesamicol was found to suppress specific binding of 125I-labelled alpha-bungarotoxin to cockroach nervous tissue with an IC50 value of 5.1 x 10(-3) mol1(-1) and an estimated Hill coefficient of 0.73. Differences in the Hill coefficients were found when the resolved stereoisomers were tested separately. These data provide the first demonstration of a blocking action by vesamicol of a neuronal nicotinic acetylcholine receptor.
ESTHER : Buckingham_1993_J.Exp.Biol_182_255
PubMedSearch : Buckingham_1993_J.Exp.Biol_182_255
PubMedID: 8228781

Title : Acetylcholine receptor molecules of the nematode Caenorhabditis elegans - Fleming_1993_EXS_63_65
Author(s) : Fleming JT , Tornoe C , Riina HA , Coadwell J , Lewis JA , Sattelle DB
Ref : Exs , 63 :65 , 1993
Abstract : Receptors for acetylcholine are present in nematodes. Studies using physiological and biochemical methods have revealed the existence of nicotinic acetylcholine receptors with a novel pharmacology. Caenorhabditis elegans provides a particularly suitable organism with which to investigate such receptors using molecular genetic approaches. Mutants resistant to the cholinergic agonist (and anthelmintic drug) levamisole have permitted the isolation of a number of genes, including structural subunits of the nicotinic acetylcholine receptor. The only known viable mutants of nicotinic receptors are those of Caenorhabditis elegans. This organism offers the prospect of studying the developmental and regulatory effects of the loss of a single component of the receptor. Using Caenorhabditis elegans it is possible to select interesting phenotypic mutations by in vivo mutagenesis before determining the causative lesion. Resistance genes other than those encoding structural subunits are of particular interest, as they will encode additional polypeptides closely associated with nicotinic receptor function. Such proteins are often difficult or impossible to identify using conventional biochemical approaches, whereas genetic selection should permit their identification.
ESTHER : Fleming_1993_EXS_63_65
PubMedSearch : Fleming_1993_EXS_63_65
PubMedID: 8422541

Title : Actions of a coral toxin analogue (bipinnatin-B) on an insect nicotinic acetylcholine receptor - Bai_1993_Arch.Insect.Biochem.Physiol_23_155
Author(s) : Bai D , Abramson SN , Sattelle DB
Ref : Archives of Insect Biochemistry & Physiology , 23 :155 , 1993
Abstract : The lophotoxin analogue, bipinnatin-B, is a potent neurotoxin isolated from the gorgonian coral Pseudopterogorgia bipinnata. When tested on the cell body of an identified motor neurone, the fast coxal depressor motor neurone (Df) in the cockroach metathoracic ganglion, bipinnatin-B, at concentrations of 10 micronM,partially blocked nicotine-induced depolarization. Blockade of the response to nicotine was almost complete at 30 micronM bipinnatin-B, and was partially reversible on rebathing the preparation in normal saline. Responses of the same neurone to GABA were unaffected by 30 micronM bipinnatin-B.
ESTHER : Bai_1993_Arch.Insect.Biochem.Physiol_23_155
PubMedSearch : Bai_1993_Arch.Insect.Biochem.Physiol_23_155
PubMedID: 21313781

Title : Neosurugatoxin blocks an alpha-bungarotoxin-sensitive neuronal nicotinic acetylcholine receptor - Bai_1993_Arch.Insect.Biochem.Physiol_23_161
Author(s) : Bai D , Sattelle DB
Ref : Archives of Insect Biochemistry & Physiology , 23 :161 , 1993
Abstract : Neosurugatoxin (NSTX), a neurotoxin isolated from the Japanese ivory mollusc Babylonia japonica, is a potent neuronal nicotinic acetylcholine receptor (nAChR) antagonist. Hitherto, NSTX has been found to block only neuronal nAChRs that are insensitive to alpha-Bgt. Here, we report for the first time that NSTX blocks an alpha-Bgt-sensitive nAChR on an identified insect motor neurone. Bath-applied NSTX at a concentration of 10 nM and above reversibly blocks the nicotine-induced depolarizations recorded from the cockroach (Periplaneta americana) fast coxal depressor motor neurone (Df) and is without effect on GABA-induced responses detected on the same cell. NSTX is among the most potent blockers tested to date on nAChRs of motor neurone Df.
ESTHER : Bai_1993_Arch.Insect.Biochem.Physiol_23_161
PubMedSearch : Bai_1993_Arch.Insect.Biochem.Physiol_23_161
PubMedID: 8358070

Title : A sulphydryl reducing agent, dithiothreitol, modifies agonist-nicotinic receptor interaction in an identified insect neurone -
Author(s) : Leech CA , Bai D , Sattelle DB
Ref : J Exp Biol , 169 :267 , 1992
PubMedID: 21313779

Title : Multiple conductances of neuronal nicotinic acetylcholine receptors - Leech_1992_Neuropharmacol_31_501
Author(s) : Leech CA , Sattelle DB
Ref : Neuropharmacology , 31 :501 , 1992
Abstract : In the presence of acetylcholine, cationic channels with three different conductances were recorded from neurones of the dissociated housefly (Musca domestica). Large conductance (80 pS) channels, resembling those that are abundant in reconstitution studies with a 65 kDa alpha-bungarotoxin affinity purified polypeptide, were detected in situ. The two larger conductance channels (80 pS; 32 pS) exhibited open and closed times that were best fitted by multiple exponential functions, indicating the presence of at least two open states. A third conductance (20 pS) showed brief, sparse openings and was least frequently observed. The 32 pS channel was the most common.
ESTHER : Leech_1992_Neuropharmacol_31_501
PubMedSearch : Leech_1992_Neuropharmacol_31_501
PubMedID: 1528401

Title : Actions of a series of bisquaternary compounds on nicotinic acetylcholine receptors in insects: ligand binding and electrophysiological studies - Lummis_1992_Neuropharmacol_31_379
Author(s) : Lummis SC , Buckingham SD , Balk ML , Holyoke CW, Jr. , Sattelle DB
Ref : Neuropharmacology , 31 :379 , 1992
Abstract : A series of bisquaternary ammoniums, with chain lengths of between 4-12 carbon atoms (C4-C12), have been tested for their ability to block acetylcholine-induced responses in the fast coxal depressor motor neurone (Df) of the cockroach (Periplaneta americana) and to displace [125I]alpha-bungarotoxin from membrane preparations of the CNS of the cockroach. The physiological studies showed that tetramethonium was inactive, whereas hexa-, octa- and dodecamethonium showed an enhanced ability to block acetylcholine-induced responses as the chain length increased. Decamethonium resulted in a slight increase in acetylcholine-induced depolarizations. Ligand binding studies showed that the ability of the compounds to inhibit the specific binding of [125I]alpha-bungarotoxin increased with size from C4-C12. The results show that neuronal nicotinic receptors in insects differ in aspects of their pharmacology from both the major subclasses of nicotinic receptors of vertebrates.
ESTHER : Lummis_1992_Neuropharmacol_31_379
PubMedSearch : Lummis_1992_Neuropharmacol_31_379
PubMedID: 1522955

Title : Acetylcholine receptors of thoracic dorsal midline neurones in the cockroach, Periplaneta Americana - Bai_1992_Arch.Insect.Biochem.Physiol_21_289
Author(s) : Bai D , Erdbrugger H , Breer H , Sattelle DB
Ref : Archives of Insect Biochemistry & Physiology , 21 :289 , 1992
Abstract : The actions of acetylcholine and cholinergic ligands have been studied using dorsal midline neurones from the rnetathoracic ganglion of the cockroach Periplaneta americana.Both nicotine and oxotremorine depolarized dorsal midline neuronal cell bodies.Dose-response curves for nicotine and oxotremorine saturated at different levels. Nicotine-induced depolarizations were completely or partially blocked by mecamylamine, d-tubocurarine, strychnine, and bicuculline, but were insensitive to alpha-bungarotoxin(100 nM), atropine (100 micronM),Scopolamine (10 micronM), and pirenzepine (50 micronM). Following pretreatment with collagenase, the dorsal midline neurones were sensitive to high doses of alpha-bungarotoxin (3 micronM). Oxotremorine-induced depolarizations were blocked by scopolamine (10 micronM) atropine (100 micronM), and pirenzepine (50 micronM) and were insensitive to mecamylamine (10 micronM) and d-tubocurarine (100 micronM). The results indicate the coexistence of at least two distinct acetylcholine receptors on dorsal midline neuronal cell bodies in the cockroach metathoracic ganglion.
ESTHER : Bai_1992_Arch.Insect.Biochem.Physiol_21_289
PubMedSearch : Bai_1992_Arch.Insect.Biochem.Physiol_21_289
PubMedID: 21313780

Title : Quasi-elastic laser light-scattering studies of size and dispersity of secretory vesicles and neurosecretosomes isolated from vertebrate neurohypophyses -
Author(s) : Sattelle DB , Obaid AL , Salzberg BM
Ref : Biochemical Society Transactions , 19 :501 , 1991
PubMedID: 1889664

Title : Nitromethylene actions on in situ and expressed insect nicotinic acetylcholine receptors - Leech_1991_FEBS.Lett_290_90
Author(s) : Leech CA , Jewess P , Marshall J , Sattelle DB
Ref : FEBS Letters , 290 :90 , 1991
Abstract : Single channel recordings from dissociated housefly (Musca domestica) neurons show that a novel type of nitromethylene insecticide, 2(nitro-methylene)tetrahydro-1,3-thiazine (NMTHT) gates a channel, the conductance and open time histogram of which resemble those obtained when acetylcholine is the agonist. Injection into Xenopus oocytes of a locust (Schistocerca gregaria) alpha-subunit mRNA results in the expression of functional nicotinic receptors sensitive to NMTHT. Control oocytes injected with distilled water are insensitive to the same concentration of this compound. Thus NMTHT exhibits agonist actions at both in situ and expressed insect nicotinic receptors, and one site of action of this compound is on an insect nicotinic receptor alpha-subunit.
ESTHER : Leech_1991_FEBS.Lett_290_90
PubMedSearch : Leech_1991_FEBS.Lett_290_90
PubMedID: 1717317

Title : Cholinergic nerve terminals in the central nervous system of insects -
Author(s) : Sattelle DB , Breer H
Ref : J Neuroendocrinol , 2 :241 , 1990
PubMedID: 19215342

Title : Cloned genes for ligand-operated ion channels and their expression in vitro -
Author(s) : Barnard EA , Darlinson MG , Harvey R , Marshall J , Moss SJ , Sattelle DB , Smart TG , Vreugdenhil E
Ref : Adv Second Messenger Phosphoprotein Res , 24 :20 , 1990
PubMedID: 1698406

Title : Sequence and functional expression of a single alpha subunit of an insect nicotinic acetylcholine receptor - Marshall_1990_EMBO.J_9_4391
Author(s) : Marshall J , Buckingham SD , Shingai R , Lunt GG , Goosey MW , Darlison MG , Sattelle DB , Barnard EA
Ref : EMBO Journal , 9 :4391 , 1990
Abstract : We report the isolation and sequence of a cDNA clone that encodes a locust (Schistocerca gregaria) nervous system nicotinic acetylcholine receptor (AChR) subunit (alpha L1). The calculated molecular weight of the unglycosylated polypeptide, which contains in the proposed extracellular domain two adjacent cysteine residues which are characteristic of alpha (ligand binding) subunits, is 60,641 daltons. Injection into Xenopus oocytes, of RNA synthesized from this clone in vitro, results in expression of functional nicotinic receptors in the oocyte membrane. In these, nicotine opens a cation channel; the receptors are blocked by both alpha-bungarotoxin (alpha-Bgt) and kappa-bungarotoxin (kappa-Bgt). Reversible block of the expressed insect AChR by mecamylamine, d-tubocurarine, tetraethylammonium, bicuculline and strychnine has also been observed. These data are entirely consistent with previously reported electrophysiological studies on in vivo insect nicotinic receptors and also with biochemical studies on an alpha-Bgt affinity purified locust AChR. Thus, a functional receptor exhibiting the characteristic pharmacology of an in vivo insect nicotinic AChR can be expressed in Xenopus oocytes by injection with a single subunit RNA.
ESTHER : Marshall_1990_EMBO.J_9_4391
PubMedSearch : Marshall_1990_EMBO.J_9_4391
PubMedID: 1702381

Title : Actions of the insecticide 2(nitromethylene)tetrahydro-1,3-thiazine on insect and vertebrate nicotinic acetylcholine receptors - Sattelle_1989_Proc.R.Soc.Lond.B.Biol.Sci_237_501
Author(s) : Sattelle DB , Buckingham SD , Wafford KA , Sherby SM , Bakry NM , Eldefrawi AT , Eldefrawi ME , May TE
Ref : Proc R Soc Lond B Biol Sci , 237 :501 , 1989
Abstract : The nitromethylene heterocyclic compound 2(nitromethylene)tetrahydro)1,3-thiazine (NMTHT) inhibits the binding of [125I]alpha-bungarotoxin to membranes prepared from cockroach (Periplaneta americana) nerve cord and fish (Torpedo californica) electric organ. Electrophysiological studies on the cockroach fast coxal depressor motorneuron (Df) reveal a dose-dependent depolarization in response to bath-applied NMTHT. Responses to ionophoretic application of NMTHT onto the cell-body membrane of motorneuron Df are suppressed by bath-applied mecamylamine (1.0 x 10(-4) M) and alpha-bungarotoxin (1.0 x 10(-7) M). These findings, together with the detection of a reversal potential close to that estimated for acetylcholine, provide evidence for an agonist action of this nitromethylene on an insect neuronal nicotinic acetylcholine receptor. The binding of [3H]H12-histrionicotoxin to Torpedo membranes was enhanced in the presence of NMTHT indicating an agonist action at this vertebrate peripheral nicotinic acetylcholine receptor. NMTHT is ineffective in radioligand binding assays for rat brain GABAA receptors, rat brain L-glutamate receptors and insect (Musca domestica) L-glutamate receptors. Partial block of rat brain muscarinic acetylcholine receptors is detected at millimolar concentrations of NMTHT. Thus nitromethylenes appear to exhibit selectivity for acetylcholine receptors and exhibit an agonist action at nicotinic acetylcholine receptors.
ESTHER : Sattelle_1989_Proc.R.Soc.Lond.B.Biol.Sci_237_501
PubMedSearch : Sattelle_1989_Proc.R.Soc.Lond.B.Biol.Sci_237_501
PubMedID: 2479949

Title : Immunocytochemical localization of nicotinic acetylcholine receptors in the terminal abdominal ganglion of the cockroach (Periplaneta americana) - Sattelle_1989_Proc.R.Soc.Lond.B.Biol.Sci_238_189
Author(s) : Sattelle DB , Madler U , Heilgenberg H , Breer H
Ref : Proc R Soc Lond B Biol Sci , 238 :189 , 1989
Abstract : A polyclonal, monospecific antiserum raised against a nicotinic acetylcholine receptor protein affinity-purified from insect nervous tissue, was employed to demonstrate the localization of antigenic sites in the neuropile of the terminal (sixth) abdominal ganglion of the cockroach Periplaneta americana. In agreement with previously published autoradiographic mapping of specific [125I]alpha-bungarotoxin binding sites, specific areas of the central neuropile of this ganglion were densely stained, but not the cercal afferent axons. No staining was detected corresponding to the dense, peripheral, partly non-specific binding of alpha-bungarotoxin seen in autoradiographs of the same tissue. Certain peripherally located neuronal cell bodies, including the cell body of giant interneuron 2, contained intracellularly located antigenic sites.
ESTHER : Sattelle_1989_Proc.R.Soc.Lond.B.Biol.Sci_238_189
PubMedSearch : Sattelle_1989_Proc.R.Soc.Lond.B.Biol.Sci_238_189
PubMedID: 2575751

Title : Allosteric inhibition of nicotinic acetylcholine receptors of vertebrates and insects by philanthotoxin - Rozental_1989_J.Pharmacol.Exp.Ther_249_123
Author(s) : Rozental R , Scoble GT , Albuquerque EX , Idriss M , Sherby S , Sattelle DB , Nakanishi K , Konno K , Eldefrawi AT , Eldefrawi ME
Ref : Journal of Pharmacology & Experimental Therapeutics , 249 :123 , 1989
Abstract : The effects of pure philanthotoxin (PhTX), a component of the venom of the wasp Philanthus triangulum, were studied on nicotinic acetylcholine receptors (nAChRs) of vertebrates and insects so as to compare their sensitivities and the mechanism of action of PhTX. Electrophysiological techniques were used on frog muscles and cockroach thoracic ganglia and biochemical techniques were applied to membranes from Torpedo electric organ and honeybee brain. PhTX (1-20 microM) inhibited reversibly the indirectly elicited muscle twitch and reduced the endplate current peak amplitude and its decay time constant in a concentration-dependent manner. In patch clamp studies, PhTX (1-5 microM) when combined with acetylcholine, induced a concentration-dependent decrease in frequency of channel openings and in channel open and burst times. The cockroach fast coxal depressor neuron was inhibited by PhTX in a time- and voltage-dependent manner. The initial rate of binding of [3H]perhydrohistrionicotoxin to Torpedo nAChR in the presence of carbamylcholine was inhibited competitively by PhTX. Binding of alpha-[125I] bungarotoxin to electric organ and honeybee brain membranes was inhibited by PhTX. Binding of [3H]acetylcholine to the electric organ receptor was potentiated by low concentrations of PhTX but inhibited by high concentrations. PhTX, therefore, inhibits both vertebrate and insect nAChRs, which may be important molecular targets for its toxicity. It is suggested that PhTX at high concentration may have some competitive action on nAChR, but it acts mainly as a blocker of the ion channel of the nAChR in its open conformation.
ESTHER : Rozental_1989_J.Pharmacol.Exp.Ther_249_123
PubMedSearch : Rozental_1989_J.Pharmacol.Exp.Ther_249_123
PubMedID: 2468760

Title : Kappa-bungarotoxin blocks an alpha-bungarotoxin-sensitive nicotinic receptor in the insect central nervous system - Pinnock_1988_Brain.Res_458_45
Author(s) : Pinnock RD , Lummis SC , Chiappinelli VA , Sattelle DB
Ref : Brain Research , 458 :45 , 1988
Abstract : Snake venom kappa-neurotoxins are selective antagonists of nicotinic acetylcholine responses in avian, murine and bovine neurons, and have been used as probes for functionally defined vertebrate neuronal nicotinic receptors. The actions of kappa-bungarotoxin, a kappa-neurotoxin, have now been examined at a central invertebrate nicotinic receptor. kappa-Bungarotoxin is a potent antagonist (IC50 = 100 nM) of nicotinic responses, producing a long-lasting blockade of insect nicotinic acetylcholine receptors. The blockade appears to be competitive, and voltage-clamp experiments on an identified cockroach motorneuron indicate that the actions of kappa-bungarotoxin are not dependent on membrane potential. alpha-Bungarotoxin is also a potent antagonist at the cockroach central nicotinic receptor, and binds (Kd = 4.3 nM) to a nicotinic site in cockroach nervous tissue. kappa-Bungarotoxin recognizes this invertebrate nicotinic site with high affinity (Ki = 27 nM). A comparison of the pharmacological properties of insect nicotinic receptors with those of functionally defined receptors identified by kappa-neurotoxins in avian autonomic ganglia reveals several similarities. However, a striking exception is alpha-bungarotoxin, which is the most potent antagonist examined at cockroach nicotinic receptors, but fails to recognize functional autonomic ganglia nicotinic receptors even at very high concentrations. It is concluded that kappa-neurotoxins can be used as selective probes for neuronal nicotinic receptors in both vertebrates and invertebrates. Although invertebrates diverged from vertebrates over 600 million years ago, the results indicate that the neuronal nicotinic receptors found in species as diverse as cockroach and chick retain considerable structural similarity, and thus neuronal nicotinic receptors appear to be highly conserved membrane proteins.
ESTHER : Pinnock_1988_Brain.Res_458_45
PubMedSearch : Pinnock_1988_Brain.Res_458_45
PubMedID: 3208100

Title : Actions of potent cholinergic anthelmintics (morantel, pyrantel and levamisole) on an identified insect neurone reveal pharmacological differences between nematode and insect acetylcholine receptors - Pinnock_1988_Neuropharmacol_27_843
Author(s) : Pinnock RD , Sattelle DB , Gration KA , Harrow ID
Ref : Neuropharmacology , 27 :843 , 1988
Abstract : Intracellular recording and current-clamp techniques were used to investigate the cholinergic activity of the anthelmintics, morantel, pyrantel and levamisole, applied to the fast coxal depressor motorneurone (Df) of the cockroach Periplaneta americana. Application of these agents and acetylcholine to the bath resulted in dose-dependent changes in conductance and corresponding depolarization of the neuronal membrane. Relative potencies of the drugs were determined from dose-response relationships and the rank order of effectiveness was as follows: carbachol much greater than levamisole greater than pyrantel greater than morantel. Evidence that these drugs were acting at the same site of action was obtained with the antagonist, mecamylamine, which abolished the responses to all these agents. It is concluded that the weak insecticidal action of these potent anthelmintics may result in part from their weak cholinergic agonist action on insect neurones, which contrasts with their potent agonist actions on acetylcholine receptors of helminth nerve and muscle tissues. The striking differences in potency on different invertebrate tissues appears to reflect differences in the properties of acetylcholine receptors between insects and nematodes. Further characterization of neurotransmitter receptors in invertebrates is needed in order to facilitate the rational design of broad-spectrum antiparasitic agents with low toxicity in mammals.
ESTHER : Pinnock_1988_Neuropharmacol_27_843
PubMedSearch : Pinnock_1988_Neuropharmacol_27_843
PubMedID: 3216964

Title : The cross-linking reagent dimethyl suberimate modifies the target size of an insect nervous system nicotinic acetylcholine receptor - Lummis_1988_Neurosci.Lett_87_145
Author(s) : Lummis SC , Ellory JC , Sattelle DB
Ref : Neuroscience Letters , 87 :145 , 1988
Abstract : Radiation inactivation and simple target theory were employed to determine the molecular weight of an insect CNS alpha-bungarotoxin binding component in the presence and absence of a cross-linking reagent, dimethyl suberimate. In the presence of the cross-linker, the number of binding sites decreased, and the apparent molecular weight (236,000) was approximately double the control value (112,000). This, together with sedimentation data, suggests that the lower value represents only a portion of the insect nicotinic receptor molecule. A model is presented to account for the increase in target size and reduction in the number of alpha-[3H]bungarotoxin binding sites in the presence of dimethyl suberimate.
ESTHER : Lummis_1988_Neurosci.Lett_87_145
PubMedSearch : Lummis_1988_Neurosci.Lett_87_145
PubMedID: 3380333

Title : Internal presynaptic tetraethylammonium (TEA+) blocks cholinergic transmission at a synapse between identified neurones - Blagburn_1987_Neurosci.Lett_73_161
Author(s) : Blagburn JM , Sattelle DB
Ref : Neuroscience Letters , 73 :161 , 1987
Abstract : Intracellular microelectrodes were used to study a cholinergic synapse between two identified neurones: the lateral filiform hair sensory neurone (LFHSN) and giant interneurone 3 (GI 3) in the terminal ganglion of the first-instar cockroach Periplaneta americana. The presynaptic neurone (LFHSN) was impaled in a region of the axon which forms large numbers of output synapses onto GI 3. Intracellular injection of tetraethylammonium (TEA+) into LFHSN blocked LFHSN-GI 3 synaptic transmission. Injection of TEA+ and either acetylcholine (ACh) or choline into the axon preserved synaptic transmission. TEA+ may compete with choline at an intracellular site involved in the maintenance of releaseable ACh.
ESTHER : Blagburn_1987_Neurosci.Lett_73_161
PubMedSearch : Blagburn_1987_Neurosci.Lett_73_161
PubMedID: 3029637

Title : Nicotinic acetylcholine receptors on a cholinergic nerve terminal in the cockroach, Periplaneta americana - Blagburn_1987_J.Comp.Physiol.A_161_215
Author(s) : Blagburn JM , Sattelle DB
Ref : J Comp Physiol A , 161 :215 , 1987
Abstract : Intracellular microelectrode recording and ionophoretic application of carbamylcholine (CCh) were used to compare the cholinergic sensitivity of postsynaptic dendrites of an identified neurone with that of an identified presynaptic cholinergic axon. The axon of the lateral filiform hair sensory neurone (LFHSN) in the first-instar cockroach Periplaneta americana was found to be as sensitive to CCh as the dendritic regions of giant interneurone 3 (GI 3). The CCh response of both neurones was unaffected by replacing Ca2+ with Mg2+, confirming that the ACh receptors are present on the neurones under test. The CCh response of both neurones was mimicked by ionophoretic application of nicotine. The responses were blocked by 10(-5) M mecamylamine and 10(-6) M d-tubocurarine and were not affected by muscarinic antagonists, suggesting that the ACh receptors present on GI 3 and LFHSN are predominantly nicotinic. The muscarinic agonist oxotremorine and the antagonists atropine and quinuclidinyl benzilate had no modulatory effect on LFHSN-GI 3 synaptic transmission. The latency of the LFHSN response to CCh was consistent with the hypothesis that ACh receptors are situated on the main axon/terminal within the neuropil of the ganglion. It has previously been shown that this region of the axon does not form output synapses (Blagburn et al. 1985a). This indirect evidence indicates that presynaptic or extrasynaptic ACh receptors are present in the membrane of a cholinergic axon. LFHSN was depolarized by synaptically-released ACh after normal or evoked spike bursts, suggesting that the nicotinic ACh receptors act as autoreceptors. However, it was not possible to obtain direct evidence to support the hypothesis that these receptors modulate ACh release.
ESTHER : Blagburn_1987_J.Comp.Physiol.A_161_215
PubMedSearch : Blagburn_1987_J.Comp.Physiol.A_161_215
PubMedID: 3040972

Title : Immunocytochemical staining of central neurones in Periplaneta americana using monoclonal antibodies to choline acetyltransferase - Sattelle_1986_Tissue.Cell_18_51
Author(s) : Sattelle DB , Ho YW , Crawford GD , Salvaterra PM , Mason WT
Ref : Tissue Cell , 18 :51 , 1986
Abstract : Immunocytochemical mapping of cholinergic neurones in the CNS of the cockroach Periplaneta americana has been attempted using monoclonal antibodies to choline acetyltransferase (ChAT, acetyl-CoA: choline O-acetyltransferase, EC Monoclonal antibodies 11 255 and 1E6 raised against rat brain ChAT and 1C8 raised against Drosophila melanogaster ChAT were ineffective in staining Periplaneta neurones. However, the cytoplasm of certain neuronal cell bodies was stained by monoclonal antibody 4D7 prepared against rat ChAT. Staining of cell bodies by 4D7 was enhanced following in vivo pre-treatment with colchicine. The staining of specific neurones by monoclonal antibody 4D7 indicates that these cockroach cells are rich in a protein with antigenic determinants resembling those of vertebrate ChAT. For some unidentified neurones, 4D7 staining is associated with the presence of acetylcholinesterase indicating that this monoclonal antibody offers a probe for mapping cholinergic neurones in the CNS of Periplaneta americana. The fast coxal depressor motoneurone (D(f)) was not stained by monoclonal antibody 4D7. Some neuronal processes in the sixth abdominal ganglion, and sensory cell bodies in the cerci were lightly stained by monoclonal antibody 4D7 following pre-injection of animals for 36 hr with colchicine.
ESTHER : Sattelle_1986_Tissue.Cell_18_51
PubMedSearch : Sattelle_1986_Tissue.Cell_18_51
PubMedID: 18620156

Title : Molecular weight estimates of insect cholinergic receptors by radiation inactivation - Lummis_1984_Neurosci.Lett_44_7
Author(s) : Lummis SC , Sattelle DB , Ellory JC
Ref : Neuroscience Letters , 44 :7 , 1984
Abstract : Molecular weight (MW) estimates for sites to which the radiolabelled cholinergic receptor probes alpha-bungarotoxin and N-methylscopolamine bind in CNS extracts of the cockroach Periplaneta americana have been made by radiation inactivation analysis. The MW of 77,600 determined for [3H]N-methylscopolamine binding sites agrees well with published values for vertebrate muscarinic acetylcholine receptor sites. In contrast, N-[propionyl-3H]propionylated alpha-bungarotoxin binds to a separate membrane component of lower MW (108,000) than previously reported values for vertebrate and insect nicotinic acetylcholine receptors. This appears to represent one or more subunits of the receptor complex, containing the recognition site.
ESTHER : Lummis_1984_Neurosci.Lett_44_7
PubMedSearch : Lummis_1984_Neurosci.Lett_44_7
PubMedID: 6717855

Title : Voltage-dependent block by histrionicotoxin of the acetylcholine-induced current in an insect motoneurone cell body - Sattelle_1983_Neurosci.Lett_43_37
Author(s) : Sattelle DB , David JA
Ref : Neuroscience Letters , 43 :37 , 1983
Abstract : Acetylcholine (ACh)-induced currents were recorded from the voltage-clamped cell body of the fast coxal depressor motoneurone of the cockroach Periplaneta americana, at membrane potentials in the range -120 mV to -60 mV. In the presence of histrionicotoxin (HTX) (1.0 X 10(-6) M), ACh currents were blocked. The blocking action of HTX was voltage-dependent, being more effective at more negative membrane potentials.
ESTHER : Sattelle_1983_Neurosci.Lett_43_37
PubMedSearch : Sattelle_1983_Neurosci.Lett_43_37
PubMedID: 6669319

Title : Pre- and post-synaptic structures in insect CNS: intramembranous features and sites of alpha-bungarotoxin binding - Lane_1983_Tissue.Cell_15_921
Author(s) : Lane NJ , Sattelle DB , Hufnagel LA
Ref : Tissue Cell , 15 :921 , 1983
Abstract : The central neuropile of thoracic ganglia in the central nervous system (CNS) of the cockroach Periplaneta americana contains synapses with characteristic pre- and post-synaptic membrane specializations and associated structures. These include dense pre-synaptic T-bars surrounded by synaptic vesicles, together with post-synaptic densities of varying electron opacity. Exocytotic release of synaptic vesicles is observed only rarely near presynaptic densities, but coated pits are seen at variable distances from them, and may be involved in membrane retrieval. After freeze-fracture, paralinear arrays of intramembranous articles (IMPs) are detected on the P face of many presynaptic terminals, with associated dimples indicative of vesicular release. The E face of these membranes exhibits protuberances complementary to the P face dimples, as well as scattered larger IMPs. Post-synaptic membranes possess dense IMP aggregates on the P face, some of which may represent receptor molecules. Electrophysiological studies with biotinylated alpha-bungarotoxin reveal that biotinylation does not inhibit the pharmacological effectiveness of the toxin in blocking acetylcholine receptors on an identified motoneurone in the metathoracic ganglion. Preliminary thin section ultrastructural analysis of this tissue post-treated with avidin-HRP or avidin-ferritin indicates that alpha-bungarotoxin-binding sites are localized at certain synapses in these insect thoracic ganglia.
ESTHER : Lane_1983_Tissue.Cell_15_921
PubMedSearch : Lane_1983_Tissue.Cell_15_921
PubMedID: 6320494

Title : Differential accessibility to two insect neurones does not account for differences in sensitivity to alpha-bungarotoxin - Lane_1982_Tissue.Cell_14_489
Author(s) : Lane NJ , Swales LS , David JA , Sattelle DB
Ref : Tissue Cell , 14 :489 , 1982
Abstract : The nicotinic acetylcholine receptor probe alpha-bungarotoxin (1.0 x 10(-7) M) blocks the depolarising response to ionophoretic application of acetylcholine onto the cell body membrane of the fast coxal depressor motoneurone (Df) of desheathed cockroach (Periplaneta americana) metathoracic ganglia, but at the same concentration is completely ineffective in blocking the depolarising action af acetylcholine on dorsal unpaired median (DUM) neurones in the same ganglion. The possibility that this is due to differences in accessibility of the toxin to the neurones has been tested by a combination of ionophoretic injection of horseradish peroxidase into single neurones with a study of the distribution of the exogenous tracer lanthanum, which is of similar effective size to alpha-bungarotoxin. The peripherally located cell body membranes and the fine axonal processes of Df and DUM neurones of desheathed metathoracic ganglia are equally accessible to lanthanum. Differential accessibility to the two cell types does not account therefore for the differences in sensitivity to alpha-bungarotoxin.
ESTHER : Lane_1982_Tissue.Cell_14_489
PubMedSearch : Lane_1982_Tissue.Cell_14_489
PubMedID: 7147226

Title : Alpha-bungarotoxin blocks excitatory post-synaptic potentials in an identified insect interneurone [proceedings] -
Author(s) : Harrow ID , Hue B , Pelhate M , Sattelle DB
Ref : Journal of Physiology , 295 :63P , 1979
PubMedID: 230337

Title : Insect acetylcholine receptors as a site of insecticide action -
Author(s) : Gepner JI , Hall LM , Sattelle DB
Ref : Nature , 276 :188 , 1978
PubMedID: 216920

Title : Cholinergic synaptic transmission in invertebrate central nervous systems [proceedings] -
Author(s) : Sattelle DB
Ref : Biochemical Society Transactions , 5 :849 , 1977
PubMedID: 21111

Title : The pharmacology of an insect ganglion: actions of carbamylcholine and acetylcholine - Sattelle_1976_J.Exp.Biol_64_13
Author(s) : Sattelle DB , McClay AS , Dowson RJ , Callec JJ
Ref : J Exp Biol , 64 :13 , 1976
Abstract : 1. Methods for presenting dose-response data for the ganglionic actions of cholinergic agonists (e.g. carbamylcholine) are compared, using the mannitol-gap technique for electrophysiological recording of synaptic events at the cercal nerve, giant fibre synapse of the sixth abdominal ganglion of the cockroach Periplaneta americana. 2. At concentrations around 10(-5)M, carbamylcholine has no effect on ganglionic polarization but potentiates the monosynaptic EPSP. At 10(-4)M and higher concentrations, ganglionic depolarization is accompanied by a reduction of EPSP. 3. Pretreatment with eserine (10(-6) M) considerably shifts the dose-response curve for acetylcholine so that synaptic transmission is consistently sensitive to 10(-6) M acetylcholine.
ESTHER : Sattelle_1976_J.Exp.Biol_64_13
PubMedSearch : Sattelle_1976_J.Exp.Biol_64_13
PubMedID: 178820

Title : Inhibitors of choline acetyltransferase as potential insecticides - Baillie_1975_Pest.Sci_6_645
Author(s) : Baillie AC , Corbett JR , Dowsett JR , Sattelle DB , Callec J-J
Ref : Pest Sci , 6 :645 , 1975
Abstract : Choline acetyltransferase (E.C. catalyses the synthesis of acetylcholine and is therefore a target for a new insecticide. We have prepared a variety of compounds, mainly choline analogues, as inhibitors of this enzyme. One of these, 2-isothiocyanatoethyltrimethylammonium iodide, has a Ki of 0.06 uM (Km for choline is 150 uM) and is apparently the most powerful inhibitor known for this enzyme. Although some of our compounds are insecticidal we believe, on the basis of electrophysiological studies, that they act, not on choline acetyltransferase, but on the acetylcholine receptor of the insect.
ESTHER : Baillie_1975_Pest.Sci_6_645
PubMedSearch : Baillie_1975_Pest.Sci_6_645