Sudhof TC


Full name : Sudhof Thomas C

First name : Thomas C

Mail : Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA

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Country : USA

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References (69)

Title : Engineered adhesion molecules drive synapse organization - Hale_2023_Proc.Natl.Acad.Sci.U.S.A_120_e2215905120
Author(s) : Hale WD , Sudhof TC , Huganir RL
Ref : Proc Natl Acad Sci U S A , 120 :e2215905120 , 2023
Abstract : In multicellular organisms, cell-adhesion molecules connect cells into tissues and mediate intercellular signaling between these cells. In vertebrate brains, synaptic cell-adhesion molecules (SAMs) guide the formation, specification, and plasticity of synapses. Some SAMs, when overexpressed in cultured neurons or in heterologous cells co-cultured with neurons, drive formation of synaptic specializations onto the overexpressing cells. However, genetic deletion of the same SAMs from neurons often has no effect on synapse numbers, but frequently severely impairs synaptic transmission, suggesting that most SAMs control the function and plasticity of synapses (i.e., organize synapses) instead of driving their initial establishment (i.e., make synapses). Since few SAMs were identified that mediate initial synapse formation, it is difficult to develop methods that enable experimental control of synaptic connections by targeted expression of these SAMs. To overcome this difficulty, we engineered novel SAMs from bacterial proteins with no eukaryotic homologues that drive synapse formation. We named these engineered adhesion proteins 'Barnoligin' and 'Starexin' because they were assembled from parts of Barnase and Neuroligin-1 or of Barstar and Neurexin3beta, respectively. Barnoligin and Starexin robustly induce the formation of synaptic specializations in a specific and directional manner in cultured neurons. Synapse formation by Barnoligin and Starexin requires both their extracellular Barnase- and Barstar-derived interaction domains and their Neuroligin- and Neurexin-derived intracellular signaling domains. Our findings support a model of synapse formation whereby trans-synaptic interactions by SAMs drive synapse organization via adhesive interactions that activate signaling cascades.
ESTHER : Hale_2023_Proc.Natl.Acad.Sci.U.S.A_120_e2215905120
PubMedSearch : Hale_2023_Proc.Natl.Acad.Sci.U.S.A_120_e2215905120
PubMedID: 36638214

Title : Astrocytic Neuroligins Are Not Required for Synapse Formation or a Normal Astrocyte Cytoarchitecture - Golf_2023_bioRxiv__
Author(s) : Golf SR , Trotter JH , Nakahara G , Sudhof TC
Ref : Biorxiv , : , 2023
Abstract : Astrocytes exert multifarious roles in the formation, regulation, and function of synapses in the brain, but the mechanisms involved remain unclear. Interestingly, astrocytes abundantly express neuroligins, postsynaptic adhesion molecules that bind to presynaptic neurexins. A pioneering recent study reported that loss-of-function of neuroligins in astrocytes impairs excitatory synapse formation and astrocyte morphogenesis. This study suggested a crucial synaptic function for astrocytic neuroligins but was puzzling given that constitutive neuroligin deletions do not decrease excitatory synapse numbers. Thus, we here examined the function of astrocytic neuroligins using a rigorous conditional genetic approach with deletion of all major neuroligins ( Nlgn1-3 ) in astrocytes. Our results show that early postnatal deletion of neuroligins from astrocytes has no effect on cortical or hippocampal synapses and does not alter the cytoarchitecture of astrocytes. Thus, astrocytic neuroligins are unlikely to shape synapse formation or astrocyte development but may perform other important functions in astrocytes.
ESTHER : Golf_2023_bioRxiv__
PubMedSearch : Golf_2023_bioRxiv__
PubMedID: 37090508

Title : Analyses of the autism-associated neuroligin-3 R451C mutation in human neurons reveal a gain-of-function synaptic mechanism - Wang_2022_Mol.Psychiatry__
Author(s) : Wang L , Mirabella VR , Dai R , Su X , Xu R , Jadali A , Bernabucci M , Singh I , Chen Y , Tian J , Jiang P , Kwan KY , Pak C , Liu C , Comoletti D , Hart RP , Chen C , Sudhof TC , Pang ZP
Ref : Mol Psychiatry , : , 2022
Abstract : Mutations in many synaptic genes are associated with autism spectrum disorders (ASD), suggesting that synaptic dysfunction is a key driver of ASD pathogenesis. Among these mutations, the R451C substitution in the NLGN3 gene that encodes the postsynaptic adhesion molecule Neuroligin-3 is noteworthy because it was the first specific mutation linked to ASDs. In mice, the corresponding Nlgn3 R451C-knockin mutation recapitulates social interaction deficits of ASD patients and produces synaptic abnormalities, but the impact of the NLGN3 R451C mutation on human neurons has not been investigated. Here, we generated human knockin neurons with the NLGN3 R451C and NLGN3 null mutations. Strikingly, analyses of NLGN3 R451C-mutant neurons revealed that the R451C mutation decreased NLGN3 protein levels but enhanced the strength of excitatory synapses without affecting inhibitory synapses; meanwhile NLGN3 knockout neurons showed reduction in excitatory synaptic strengths. Moreover, overexpression of NLGN3 R451C recapitulated the synaptic enhancement in human neurons. Notably, the augmentation of excitatory transmission was confirmed in vivo with human neurons transplanted into mouse forebrain. Using single-cell RNA-seq experiments with co-cultured excitatory and inhibitory NLGN3 R451C-mutant neurons, we identified differentially expressed genes in relatively mature human neurons corresponding to synaptic gene expression networks. Moreover, gene ontology and enrichment analyses revealed convergent gene networks associated with ASDs and other mental disorders. Our findings suggest that the NLGN3 R451C mutation induces a gain-of-function enhancement in excitatory synaptic transmission that may contribute to the pathophysiology of ASD.
ESTHER : Wang_2022_Mol.Psychiatry__
PubMedSearch : Wang_2022_Mol.Psychiatry__
PubMedID: 36280753

Title : Neuroligin-3 confines AMPA receptors into nanoclusters, thereby controlling synaptic strength at the calyx of Held synapses - Han_2022_Sci.Adv_8_eabo4173
Author(s) : Han Y , Cao R , Qin L , Chen LY , Tang AH , Sudhof TC , Zhang B
Ref : Sci Adv , 8 :eabo4173 , 2022
Abstract : The subsynaptic organization of postsynaptic neurotransmitter receptors into nanoclusters that are aligned with presynaptic release sites is essential for the high fidelity of synaptic transmission. However, the mechanisms controlling the nanoscale organization of neurotransmitter receptors in vivo remain incompletely understood. Here, we deconstructed the role of neuroligin-3 (Nlgn3), a postsynaptic adhesion molecule linked to autism, in organizing AMPA-type glutamate receptors in the calyx of Held synapse. Deletion of Nlgn3 lowered the amplitude and slowed the kinetics of AMPA receptor-mediated synaptic responses. Super-resolution microscopy revealed that, unexpectedly, these impairments in synaptic transmission were associated with an increase in the size of postsynaptic PSD-95 and AMPA receptor nanoclusters but a decrease of the densities in these clusters. Modeling showed that a dilution of AMPA receptors into larger nanocluster volumes decreases synaptic strength. Nlgn3, likely by binding to presynaptic neurexins, thus is a key organizer of AMPA receptor nanoclusters that likely acts via PSD-95 adaptors to optimize the fidelity of synaptic transmission.
ESTHER : Han_2022_Sci.Adv_8_eabo4173
PubMedSearch : Han_2022_Sci.Adv_8_eabo4173
PubMedID: 35704570

Title : The Perils of Navigating Activity-Dependent Alternative Splicing of Neurexins - Liakath-Ali_2021_Front.Mol.Neurosci_14_659681
Author(s) : Liakath-Ali K , Sudhof TC
Ref : Front Mol Neurosci , 14 :659681 , 2021
Abstract : Neurexins are presynaptic cell-adhesion molecules essential for synaptic function that are expressed in thousands of alternatively spliced isoforms. Recent studies suggested that alternative splicing at splice site 4 (SS4) of Nrxn1 is tightly regulated by an activity-dependent mechanism. Given that Nrxn1 alternative splicing at SS4 controls NMDA-receptor-mediated synaptic responses, activity-dependent SS4 alternative splicing would suggest a new synaptic plasticity mechanism. However, conflicting results confound the assessment of neurexin alternative splicing, prompting us to re-evaluate this issue. We find that in cortical cultures, membrane depolarization by elevated extracellular K(+)-concentrations produced an apparent shift in Nrxn1-SS4 alternative splicing by inducing neuronal but not astroglial cell death, resulting in persistent astroglial Nrxn1-SS4+ expression and decreased neuronal Nrxn1-SS4- expression. in vivo, systemic kainate-induced activation of neurons in the hippocampus produced no changes in Nrxn1-SS4 alternative splicing. Moreover, focal kainate injections into the mouse cerebellum induced small changes in Nrxn1-SS4 alternative splicing that, however, were associated with large decreases in Nrxn1 expression and widespread DNA damage. Our results suggest that although Nrxn1-SS4 alternative splicing may represent a mechanism of activity-dependent synaptic plasticity, common procedures for testing this hypothesis are prone to artifacts, and more sophisticated approaches will be necessary to test this important question.
ESTHER : Liakath-Ali_2021_Front.Mol.Neurosci_14_659681
PubMedSearch : Liakath-Ali_2021_Front.Mol.Neurosci_14_659681
PubMedID: 33767611

Title : Evolution of the Autism-Associated Neuroligin-4 Gene Reveals Broad Erosion of Pseudoautosomal Regions in Rodents - Maxeiner_2020_Mol.Biol.Evol__
Author(s) : Maxeiner S , Benseler F , Krasteva-Christ G , Brose N , Sudhof TC
Ref : Molecular Biology Evolution , : , 2020
Abstract : Variants in genes encoding synaptic adhesion proteins of the neuroligin family, most notably neuroligin-4, are a significant cause of autism spectrum disorders in humans. While human neuroligin-4 is encoded by two genes, NLGN4X and NLGN4Y, that are localized on the X-specific and male-specific regions of the two sex chromosomes, the chromosomal localization and full genomic sequence of the mouse Nlgn4 gene remain elusive. Here, we analyzed the neuroligin-4 genes of numerous rodent species by direct sequencing and bioinformatics, generated complete drafts of multiple rodent neuroligin-4 genes, and examined their evolution. Surprisingly, we find that the murine Nlgn4 gene is localized to the pseudoautosomal region (PAR) of the sex chromosomes, different from its human orthologues. We show that the sequence differences between various neuroligin-4 proteins are restricted to hotspots in which rodent neuroligin-4 proteins contain short repetitive sequence insertions compared to neuroligin-4 proteins from other species, whereas all other protein sequences are highly conserved. Evolutionarily, these sequence insertions initiate in the clade eumuroidea of the infra-order myomorpha, and are additionally associated with dramatic changes in non-coding sequences and gene size. Importantly, these changes are not exclusively restricted to neuroligin-4 genes but reflect major evolutionary changes that substantially altered or even deleted genes from the PARs of both sex chromosomes. Our results show that despite the fact that the PAR in rodents and the neuroligin-4 genes within the rodent PAR underwent massive evolutionary changes, neuroligin-4 proteins maintained a highly conserved core structure, consistent with a substantial evolutionary pressure preserving its physiological function.
ESTHER : Maxeiner_2020_Mol.Biol.Evol__
PubMedSearch : Maxeiner_2020_Mol.Biol.Evol__
PubMedID: 32011705
Gene_locus related to this paper: mouse-4neur

Title : SPARCL1 Promotes Excitatory But Not Inhibitory Synapse Formation and Function Independent of Neurexins and Neuroligins - Gan_2020_J.Neurosci_40_8088
Author(s) : Gan KJ , Sudhof TC
Ref : Journal of Neuroscience , 40 :8088 , 2020
Abstract : Emerging evidence supports roles for secreted extracellular matrix proteins in boosting synaptogenesis, synaptic transmission, and synaptic plasticity. SPARCL1 (also known as Hevin), a secreted non-neuronal protein, was reported to increase synaptogenesis by simultaneously binding to presynaptic neurexin-1alpha and to postsynaptic neuroligin-1B, thereby catalyzing formation of trans-synaptic neurexin/neuroligin complexes. However, neurexins and neuroligins do not themselves mediate synaptogenesis, raising the question of how SPARCL1 enhances synapse formation by binding to these molecules. Moreover, it remained unclear whether SPARCL1 acts on all synapses containing neurexins and neuroligins or only on a subset of synapses, and whether it enhances synaptic transmission in addition to boosting synaptogenesis or induces silent synapses. To explore these questions, we examined the synaptic effects of SPARCL1 and their dependence on neurexins and neuroligins. Using mixed neuronal and glial cultures from neonatal mouse cortex of both sexes, we show that SPARCL1 selectively increases excitatory but not inhibitory synapse numbers, enhances excitatory but not inhibitory synaptic transmission, and augments NMDAR-mediated synaptic responses more than AMPAR-mediated synaptic responses. None of these effects were mediated by SPARCL1-binding to neurexins or neuroligins. Neurons from triple neurexin-1/2/3 or from quadruple neuroligin-1/2/3/4 conditional KO mice that lacked all neurexins or all neuroligins were fully responsive to SPARCL1. Together, our results reveal that SPARCL1 selectively boosts excitatory but not inhibitory synaptogenesis and synaptic transmission by a novel mechanism that is independent of neurexins and neuroligins.SIGNIFICANCE STATEMENT Emerging evidence supports roles for extracellular matrix proteins in boosting synapse formation and function. Previous studies demonstrated that SPARCL1, a secreted non-neuronal protein, promotes synapse formation in rodent and human neurons. However, it remained unclear whether SPARCL1 acts on all or on only a subset of synapses, induces functional or largely inactive synapses, and generates synapses by bridging presynaptic neurexins and postsynaptic neuroligins. Here, we report that SPARCL1 selectively induces excitatory synapses, increases their efficacy, and enhances their NMDAR content. Moreover, using rigorous genetic manipulations, we show that SPARCL1 does not require neurexins and neuroligins for its activity. Thus, SPARCL1 selectively boosts excitatory synaptogenesis and synaptic transmission by a novel mechanism that is independent of neurexins and neuroligins.
ESTHER : Gan_2020_J.Neurosci_40_8088
PubMedSearch : Gan_2020_J.Neurosci_40_8088
PubMedID: 32973045

Title : Synaptic neurexin-1 assembles into dynamically regulated active zone nanoclusters - Trotter_2019_J.Cell.Biol_218_2677
Author(s) : Trotter JH , Hao J , Maxeiner S , Tsetsenis T , Liu Z , Zhuang X , Sudhof TC
Ref : Journal of Cell Biology , 218 :2677 , 2019
Abstract : Neurexins are well-characterized presynaptic cell adhesion molecules that engage multifarious postsynaptic ligands and organize diverse synapse properties. However, the precise synaptic localization of neurexins remains enigmatic. Using super-resolution microscopy, we demonstrate that neurexin-1 forms discrete nanoclusters at excitatory synapses, revealing a novel organizational feature of synaptic architecture. Synapses generally contain a single nanocluster that comprises more than four neurexin-1 molecules and that also includes neurexin-2 and/or neurexin-3 isoforms. Moreover, we find that neurexin-1 is physiologically cleaved by ADAM10 similar to its ligand neuroligin-1, with approximately 4-6% of neurexin-1 and approximately 2-3% of neuroligin-1 present in the adult brain as soluble ectodomain proteins. Blocking ADAM10-mediated neurexin-1 cleavage dramatically increased the synaptic neurexin-1 content, thereby elevating the percentage of Homer1(+) excitatory synapses containing neurexin-1 nanoclusters from 40-50% to approximately 80%, and doubling the number of neurexin-1 molecules per nanocluster. Taken together, our results reveal an unexpected nanodomain organization of synapses in which neurexin-1 is assembled into discrete presynaptic nanoclusters that are dynamically regulated via ectodomain cleavage.
ESTHER : Trotter_2019_J.Cell.Biol_218_2677
PubMedSearch : Trotter_2019_J.Cell.Biol_218_2677
PubMedID: 31262725

Title : Neuroligin-1 Signaling Controls LTP and NMDA Receptors by Distinct Molecular Pathways - Wu_2019_Neuron_102_621
Author(s) : Wu X , Morishita WK , Riley AM , Hale WD , Sudhof TC , Malenka RC
Ref : Neuron , 102 :621 , 2019
Abstract : Neuroligins, postsynaptic cell adhesion molecules that are linked to neuropsychiatric disorders, are extensively studied, but fundamental questions about their functions remain. Using in vivo replacement strategies in quadruple conditional knockout mice of all neuroligins to avoid heterodimerization artifacts, we show, in hippocampal CA1 pyramidal neurons, that neuroligin-1 performs two key functions in excitatory synapses by distinct molecular mechanisms. N-methyl-D-aspartate (NMDA) receptor-dependent LTP requires trans-synaptic binding of postsynaptic neuroligin-1 to presynaptic beta-neurexins but not the cytoplasmic sequences of neuroligins. In contrast, postsynaptic NMDA receptor (NMDAR)-mediated responses involve a neurexin-independent mechanism that requires the neuroligin-1 cytoplasmic sequences. Strikingly, deletion of neuroligins blocked the spine expansion associated with LTP, as monitored by two-photon imaging; this block involved a mechanism identical to that of the role of neuroligin-1 in NMDAR-dependent LTP. Our data suggest that neuroligin-1 performs two mechanistically distinct signaling functions and that neurolign-1-mediated trans-synaptic cell adhesion signaling critically regulates LTP.
ESTHER : Wu_2019_Neuron_102_621
PubMedSearch : Wu_2019_Neuron_102_621
PubMedID: 30871858

Title : Neuroligin-4 Regulates Excitatory Synaptic Transmission in Human Neurons - Marro_2019_Neuron_103_617
Author(s) : Marro SG , Chanda S , Yang N , Janas JA , Valperga G , Trotter J , Zhou B , Merrill S , Yousif I , Shelby H , Vogel H , Kalani MYS , Sudhof TC , Wernig M
Ref : Neuron , 103 :617 , 2019
Abstract : The autism-associated synaptic-adhesion gene Neuroligin-4 (NLGN4) is poorly conserved evolutionarily, limiting conclusions from Nlgn4 mouse models for human cells. Here, we show that the cellular and subcellular expression of human and murine Neuroligin-4 differ, with human Neuroligin-4 primarily expressed in cerebral cortex and localized to excitatory synapses. Overexpression of NLGN4 in human embryonic stem cell-derived neurons resulted in an increase in excitatory synapse numbers but a remarkable decrease in synaptic strength. Human neurons carrying the syndromic autism mutation NLGN4-R704C also formed more excitatory synapses but with increased functional synaptic transmission due to a postsynaptic mechanism, while genetic loss of NLGN4 did not significantly affect synapses in the human neurons analyzed. Thus, the NLGN4-R704C mutation represents a change-of-function mutation. Our work reveals contrasting roles of NLGN4 in human and mouse neurons, suggesting that human evolution has impacted even fundamental cell biological processes generally assumed to be highly conserved.
ESTHER : Marro_2019_Neuron_103_617
PubMedSearch : Marro_2019_Neuron_103_617
PubMedID: 31257103

Title : Alternative Splicing of Presynaptic Neurexins Differentially Controls Postsynaptic NMDA and AMPA Receptor Responses - Dai_2019_Neuron_102_993
Author(s) : Dai J , Aoto J , Sudhof TC
Ref : Neuron , 102 :993 , 2019
Abstract : AMPA- and NMDA-type glutamate receptors mediate distinct postsynaptic signals that differ characteristically among synapses. How postsynaptic AMPA- and NMDA-receptor levels are regulated, however, remains unclear. Using newly generated conditional knockin mice that enable genetic control of neurexin alternative splicing, we show that in hippocampal synapses, alternative splicing of presynaptic neurexin-1 at splice site 4 (SS4) dramatically enhanced postsynaptic NMDA-receptor-mediated, but not AMPA-receptor-mediated, synaptic responses without altering synapse density. In contrast, alternative splicing of neurexin-3 at SS4 suppressed AMPA-receptor-mediated, but not NMDA-receptor-mediated, synaptic responses, while alternative splicing of neurexin-2 at SS4 had no effect on NMDA- or AMPA-receptor-mediated responses. Presynaptic overexpression of the neurexin-1beta and neurexin-3beta SS4+ splice variants, but not of their SS4- splice variants, replicated the respective SS4+ knockin phenotypes. Thus, different neurexins perform distinct nonoverlapping functions at hippocampal synapses that are independently regulated by alternative splicing. These functions transsynaptically control NMDA and AMPA receptors, thereby mediating presynaptic control of postsynaptic responses.
ESTHER : Dai_2019_Neuron_102_993
PubMedSearch : Dai_2019_Neuron_102_993
PubMedID: 31005376

Title : Autism-associated neuroligin-4 mutation selectively impairs glycinergic synaptic transmission in mouse brainstem synapses - Zhang_2018_J.Exp.Med_215_1543
Author(s) : Zhang B , Gokce O , Hale WD , Brose N , Sudhof TC
Ref : J Exp Med , 215 :1543 , 2018
Abstract : In human patients, loss-of-function mutations of the postsynaptic cell-adhesion molecule neuroligin-4 were repeatedly identified as monogenetic causes of autism. In mice, neuroligin-4 deletions caused autism-related behavioral impairments and subtle changes in synaptic transmission, and neuroligin-4 was found, at least in part, at glycinergic synapses. However, low expression levels precluded a comprehensive analysis of neuroligin-4 localization, and overexpression of neuroligin-4 puzzlingly impaired excitatory but not inhibitory synaptic function. As a result, the function of neuroligin-4 remains unclear, as does its relation to other neuroligins. To clarify these issues, we systematically examined the function of neuroligin-4, focusing on excitatory and inhibitory inputs to defined projection neurons of the mouse brainstem as central model synapses. We show that loss of neuroligin-4 causes a profound impairment of glycinergic but not glutamatergic synaptic transmission and a decrease in glycinergic synapse numbers. Thus, neuroligin-4 is essential for the organization and/or maintenance of glycinergic synapses.
ESTHER : Zhang_2018_J.Exp.Med_215_1543
PubMedSearch : Zhang_2018_J.Exp.Med_215_1543
PubMedID: 29724786
Gene_locus related to this paper: mouse-4neur

Title : Developmental plasticity shapes synaptic phenotypes of autism-associated neuroligin-3 mutations in the calyx of Held - Zhang_2017_Mol.Psychiatry_22_1483
Author(s) : Zhang B , Seigneur E , Wei P , Gokce O , Morgan J , Sudhof TC
Ref : Mol Psychiatry , 22 :1483 , 2017
Abstract : Neuroligins are postsynaptic cell-adhesion molecules that bind to presynaptic neurexins. Mutations in neuroligin-3 predispose to autism, but how such mutations affect synaptic function remains incompletely understood. Here we systematically examined the effect of three autism-associated mutations, the neuroligin-3 knockout, the R451C knockin, and the R704C knockin, on synaptic transmission in the calyx of Held, a central synapse ideally suited for high-resolution analyses of synaptic transmission. Surprisingly, germline knockout of neuroligin-3 did not alter synaptic transmission, whereas the neuroligin-3 R451C and R704C knockins decreased and increased, respectively, synaptic transmission. These puzzling results prompted us to ask whether neuroligin-3 mutant phenotypes may be reshaped by developmental plasticity. Indeed, conditional knockout of neuroligin-3 during late development produced a marked synaptic phenotype, whereas conditional knockout of neuroligin-3 during early development caused no detectable effect, mimicking the germline knockout. In canvassing potentially redundant candidate genes, we identified developmentally early expression of another synaptic neurexin ligand, cerebellin-1. Strikingly, developmentally early conditional knockout of cerebellin-1 only modestly impaired synaptic transmission, whereas in contrast to the individual single knockouts, developmentally early conditional double knockout of both cerebellin-1 and neuroligin-3 severely decreased synaptic transmission. Our data suggest an unanticipated mechanism of developmental compensation whereby cerebellin-1 and neuroligin-3 functionally occlude each other during development of calyx synapses. Thus, although acute manipulations more likely reveal basic gene functions, developmental plasticity can be a major factor in shaping the overall phenotypes of genetic neuropsychiatric disorders.
ESTHER : Zhang_2017_Mol.Psychiatry_22_1483
PubMedSearch : Zhang_2017_Mol.Psychiatry_22_1483
PubMedID: 27725662

Title : Conditional Deletion of All Neurexins Defines Diversity of Essential Synaptic Organizer Functions for Neurexins - Chen_2017_Neuron_94_611
Author(s) : Chen LY , Jiang M , Zhang B , Gokce O , Sudhof TC
Ref : Neuron , 94 :611 , 2017
Abstract : Neurexins are recognized as key organizers of synapses that are essential for normal brain function. However, it is unclear whether neurexins are fundamental building blocks of all synapses with similar overall functions or context-dependent specifiers of synapse properties. To address this question, we produced triple cKO (conditional knockout) mice that allow ablating all neurexin expression in mice. Using neuron-specific manipulations combined with immunocytochemistry, paired recordings, and two-photon Ca2+ imaging, we analyzed excitatory synapses formed by climbing fibers on Purkinje cells in cerebellum and inhibitory synapses formed by parvalbumin- or somatostatin-positive interneurons on pyramidal layer 5 neurons in the medial prefrontal cortex. After pan-neurexin deletions, we observed in these synapses severe but dramatically different synaptic phenotypes that ranged from major impairments in their distribution and function (climbing-fiber synapses) to large decreases in synapse numbers (parvalbumin-positive synapses) and severe alterations in action potential-induced presynaptic Ca2+ transients (somatostatin-positive synapses). Thus, neurexins function primarily as context-dependent specifiers of synapses.
ESTHER : Chen_2017_Neuron_94_611
PubMedSearch : Chen_2017_Neuron_94_611
PubMedID: 28472659

Title : Modulation of excitation on parvalbumin interneurons by neuroligin-3 regulates the hippocampal network - Polepalli_2017_Nat.Neurosci_20_219
Author(s) : Polepalli JS , Wu H , Goswami D , Halpern CH , Sudhof TC , Malenka RC
Ref : Nat Neurosci , 20 :219 , 2017
Abstract : Hippocampal network activity is generated by a complex interplay between excitatory pyramidal cells and inhibitory interneurons. Although much is known about the molecular properties of excitatory synapses on pyramidal cells, comparatively little is known about excitatory synapses on interneurons. Here we show that conditional deletion of the postsynaptic cell adhesion molecule neuroligin-3 in parvalbumin interneurons causes a decrease in NMDA-receptor-mediated postsynaptic currents and an increase in presynaptic glutamate release probability by selectively impairing the inhibition of glutamate release by presynaptic Group III metabotropic glutamate receptors. As a result, the neuroligin-3 deletion altered network activity by reducing gamma oscillations and sharp wave ripples, changes associated with a decrease in extinction of contextual fear memories. These results demonstrate that neuroligin-3 specifies the properties of excitatory synapses on parvalbumin-containing interneurons by a retrograde trans-synaptic mechanism and suggest a molecular pathway whereby neuroligin-3 mutations contribute to neuropsychiatric disorders.
ESTHER : Polepalli_2017_Nat.Neurosci_20_219
PubMedSearch : Polepalli_2017_Nat.Neurosci_20_219
PubMedID: 28067903

Title : Unique versus Redundant Functions of Neuroligin Genes in Shaping Excitatory and Inhibitory Synapse Properties - Chanda_2017_J.Neurosci_37_6816
Author(s) : Chanda S , Hale WD , Zhang B , Wernig M , Sudhof TC
Ref : Journal of Neuroscience , 37 :6816 , 2017
Abstract : Neuroligins are evolutionarily conserved postsynaptic cell adhesion molecules that interact with presynaptic neurexins. Neurons express multiple neuroligin isoforms that are targeted to specific synapses, but their synaptic functions and mechanistic redundancy are not completely understood. Overexpression or RNAi-mediated knockdown of neuroligins, respectively, causes a dramatic increase or decrease in synapse density, whereas genetic deletions of neuroligins impair synapse function with only minor effects on synapse numbers, raising fundamental questions about the overall physiological role of neuroligins. Here, we have systematically analyzed the effects of conditional genetic deletions of all major neuroligin isoforms (i.e., NL1, NL2, and NL3), either individually or in combinations, in cultured mouse hippocampal and cortical neurons. We found that conditional genetic deletions of neuroligins caused no change or only a small change in synapses numbers, but strongly impaired synapse function. This impairment was isoform specific, suggesting that neuroligins are not functionally redundant. Sparse neuroligin deletions produced phenotypes comparable to those of global deletions, indicating that neuroligins function in a cell-autonomous manner. Mechanistically, neuroligin deletions decreased the synaptic levels of neurotransmitter receptors and had no effect on presynaptic release probabilities. Overexpression of neuroligin-1 in control or neuroligin-deficient neurons increased synaptic transmission and synapse density but not spine numbers, suggesting that these effects reflect a gain-of-function mechanism; whereas overexpression of neuroligin-3, which, like neuroligin-1 is also targeted to excitatory synapses, had no comparable effect. Our data demonstrate that neuroligins are required for the physiological organization of neurotransmitter receptors in postsynaptic specializations and suggest that they do not play a major role in synapse formation.SIGNIFICANCE STATEMENT Human neuroligin genes have been associated with autism, but the cellular functions of different neuroligins and their molecular mechanisms remain incompletely understood. Here, we performed comparative analyses in cultured mouse neurons of all major neuroligin isoforms, either individually or in combinations, using conditional knockouts. We found that neuroligin deletions did not affect synapse numbers but differentially impaired excitatory or inhibitory synaptic functions in an isoform-specific manner. These impairments were due, at least in part, to a decrease in synaptic distribution of neurotransmitter receptors upon deletion of neuroligins. Conversely, the overexpression of neuroligin-1 increased synapse numbers but not spine numbers. Our results suggest that various neuroligin isoforms perform unique postsynaptic functions in organizing synapses but are not essential for synapse formation or maintenance.
ESTHER : Chanda_2017_J.Neurosci_37_6816
PubMedSearch : Chanda_2017_J.Neurosci_37_6816
PubMedID: 28607166

Title : Conditional ablation of neuroligin-1 in CA1 pyramidal neurons blocks LTP by a cell-autonomous NMDA receptor-independent mechanism - Jiang_2017_Mol.Psychiatry_22_375
Author(s) : Jiang M , Polepalli J , Chen LY , Zhang B , Sudhof TC , Malenka RC
Ref : Mol Psychiatry , 22 :375 , 2017
Abstract : Neuroligins are postsynaptic cell-adhesion molecules implicated in autism and other neuropsychiatric disorders. Despite extensive work, the role of neuroligins in synapse function and plasticity, especially N-methyl-d-aspartate (NMDA) receptor (NMDAR)-dependent long-term potentiation (LTP), remains unclear. To establish which synaptic functions unequivocally require neuroligins, we analyzed single and triple conditional knockout (cKO) mice for all three major neuroligin isoforms (NL1-NL3). We inactivated neuroligins by stereotactic viral expression of Cre-recombinase in hippocampal CA1 region pyramidal neurons at postnatal day 0 (P0) or day 21 (P21) and measured synaptic function, synaptic plasticity and spine numbers in acute hippocampal slices 2-3 weeks later. Surprisingly, we find that ablation of neuroligins in newborn or juvenile mice only modestly impaired basal synaptic function in hippocampus and caused no alteration in postsynaptic spine numbers. However, triple cKO of NL1-NL3 or single cKO of NL1 impaired NMDAR-mediated excitatory postsynaptic currents and abolished NMDAR-dependent LTP. Strikingly, the NL1 cKO also abolished LTP elicited by activation of L-type Ca2+-channels during blockade of NMDARs. These findings demonstrate that neuroligins are generally not essential for synapse formation in CA1 pyramidal neurons but shape synaptic properties and that NL1 specifically is required for LTP induced by postsynaptic Ca2+-elevations, a function which may contribute to the pathophysiological role of neuroligins in brain disorders.
ESTHER : Jiang_2017_Mol.Psychiatry_22_375
PubMedSearch : Jiang_2017_Mol.Psychiatry_22_375
PubMedID: 27217145

Title : Neuroligins Are Selectively Essential for NMDAR Signaling in Cerebellar Stellate Interneurons - Zhang_2016_J.Neurosci_36_9070
Author(s) : Zhang B , Sudhof TC
Ref : Journal of Neuroscience , 36 :9070 , 2016
Abstract : Neuroligins are postsynaptic cell-adhesion molecules that contribute to synapse specification. However, many other postsynaptic cell-adhesion molecules are known and the relative contributions of neuroligins versus other such molecules in different types of synapses and neurons remains largely unknown. Here, we have studied the role of neuroligins in cerebellar stellate interneurons that participate in a well defined circuit that converges on Purkinje cells as the major output neurons of cerebellar cortex. By crossing triple conditional knock-out (cKO) mice targeting all three major neuroligins [neuroligin-1 to neuroligin-3 (NL123)] with parvalbumin-Cre (PV-Cre) transgenic mice, we deleted neuroligins from inhibitory cerebellar interneurons and Purkinje cells, allowing us to study the effects of neuroligin deletions on cerebellar stellate cell synapses by electrophysiology in acute slices. PV-Cre/NL123 cKO mice did not exhibit gross alterations of cerebellar structure or cerebellar interneuron morphology. Strikingly, electrophysiological recordings in stellate cells from these PV-Cre/NL123 cKO mice revealed a large decrease in NMDAR-mediated excitatory synaptic responses, which, in stellate cells, are largely extrasynaptic, without a change in AMPA-receptor-mediated responses. Parallel analyses in PV-Cre/NL1 mice that are single NL1 cKO mice uncovered the same phenotype, demonstrating that NL1 is responsible for recruiting extrasynaptic NMDARs. Moreover, we observed only a modest impairment in inhibitory synaptic responses in stellate cells lacking NL123 despite a nearly complete suppression of inhibitory synaptic transmission in Purkinje cells by the same genetic manipulation. Our results suggest that, unlike other types of neurons investigated, neuroligins are selectively essential in cerebellar stellate interneurons for enabling the function of extrasynaptic NMDARs. SIGNIFICANCE STATEMENT: Neuroligins are postsynaptic cell-adhesion molecules genetically linked to autism. However, the contributions of neuroligins to interneuron functions remain largely unknown. Here, we analyzed the role of neuroligins in cerebellar stellate interneurons. We deleted neuroligin-1, neuroligin-2, and neuroligin-3, the major cerebellar neuroligin isoforms, from stellate cells in triple NL123 conditional knock-out mice and analyzed synaptic responses by acute slice electrophysiology. We find that neuroligins are selectively essential for extrasynaptic NMDAR-mediated signaling, but dispensable for both AMPAR-mediated and inhibitory synaptic transmission. Our results reveal a critical and selective role for neuroligins in the regulation of NMDAR responses in cerebellar stellate interneurons.
ESTHER : Zhang_2016_J.Neurosci_36_9070
PubMedSearch : Zhang_2016_J.Neurosci_36_9070
PubMedID: 27581450

Title : Pathogenic mechanism of an autism-associated neuroligin mutation involves altered AMPA-receptor trafficking - Chanda_2016_Mol.Psychiatry_21_169
Author(s) : Chanda S , Aoto J , Lee SJ , Wernig M , Sudhof TC
Ref : Mol Psychiatry , 21 :169 , 2016
Abstract : Neuroligins are postsynaptic cell-adhesion molecules that bind to presynaptic neurexins. Although the general synaptic role of neuroligins is undisputed, their specific functions at a synapse remain unclear, even controversial. Moreover, many neuroligin gene mutations were associated with autism, but the pathophysiological relevance of these mutations is often unknown, and their mechanisms of action uninvestigated. Here, we examine the synaptic effects of an autism-associated neuroligin-4 substitution (called R704C), which mutates a cytoplasmic arginine residue that is conserved in all neuroligins. We show that the R704C mutation, when introduced into neuroligin-3, enhances the interaction between neuroligin-3 and AMPA receptors, increases AMPA-receptor internalization and decreases postsynaptic AMPA-receptor levels. When introduced into neuroligin-4, conversely, the R704C mutation unexpectedly elevated AMPA-receptor-mediated synaptic responses. These results suggest a general functional link between neuroligins and AMPA receptors, indicate that both neuroligin-3 and -4 act at excitatory synapses but perform surprisingly distinct functions, and demonstrate that the R704C mutation significantly impairs the normal function of neuroligin-4, thereby validating its pathogenicity.
ESTHER : Chanda_2016_Mol.Psychiatry_21_169
PubMedSearch : Chanda_2016_Mol.Psychiatry_21_169
PubMedID: 25778475

Title : Conditional neuroligin-2 knockout in adult medial prefrontal cortex links chronic changes in synaptic inhibition to cognitive impairments - Liang_2015_Mol.Psychiatry_20_850
Author(s) : Liang J , Xu W , Hsu YT , Yee AX , Chen L , Sudhof TC
Ref : Mol Psychiatry , 20 :850 , 2015
Abstract : Abnormal activity in the medial prefrontal cortex (mPFC) is consistently observed in neuropsychiatric disorders, but the mechanisms involved remain unclear. Chronic aberrant excitation and/or inhibition of mPFC neurons were proposed to cause cognitive impairments. However, direct evidence for this hypothesis is lacking because it is technically challenging to control synaptic properties in a chronic and locally restricted, yet specific, manner. Here, we generated conditional knockout (cKO) mice of neuroligin-2 (Nlgn2), a postsynaptic cell-adhesion molecule of inhibitory synapses linked to neuropsychiatric disorders. cKO of Nlgn2 in adult mPFC rendered Nlgn2 protein undetectable after already 2-3 weeks, but induced major reductions in synaptic inhibition after only 6-7 weeks, and caused parallel impairments in anxiety, fear memory and social interaction behaviors. Moreover, cKO of Nlgn2 severely impaired behavioral stimulation of immediate-early gene expression in the mPFC, suggesting that chronic reduction in synaptic inhibition uncoupled the mPFC from experience-dependent inputs. Our results indicate that Nlgn2 is required for continuous maintenance of inhibitory synapses in the adult mPFC, and that chronic impairment of local inhibition disengages the mPFC from its cognitive functions by partially uncoupling the mPFC from experience-induced inputs.
ESTHER : Liang_2015_Mol.Psychiatry_20_850
PubMedSearch : Liang_2015_Mol.Psychiatry_20_850
PubMedID: 25824299

Title : Neuroligins Sculpt Cerebellar Purkinje-Cell Circuits by Differential Control of Distinct Classes of Synapses - Zhang_2015_Neuron_87_781
Author(s) : Zhang B , Chen LY , Liu X , Maxeiner S , Lee SJ , Gokce O , Sudhof TC
Ref : Neuron , 87 :781 , 2015
Abstract : Neuroligins are postsynaptic cell-adhesion molecules that bind presynaptic neurexins and are genetically linked to autism. Neuroligins are proposed to organize synaptogenesis and/or synaptic transmission, but no systematic analysis of neuroligins in a defined circuit is available. Here, we show that conditional deletion of all neuroligins in cerebellar Purkinje cells caused loss of distal climbing-fiber synapses and weakened climbing-fiber but not parallel-fiber synapses, consistent with alternative use of neuroligins and cerebellins as neurexin ligands for the excitatory climbing-fiber versus parallel-fiber synapses. Moreover, deletion of neuroligins increased the size of inhibitory basket/stellate-cell synapses but simultaneously severely impaired their function. Multiple neuroligin isoforms differentially contributed to climbing-fiber and basket/stellate-cell synapse functions, such that inhibitory synapse-specific neuroligin-2 was unexpectedly essential for maintaining normal climbing-fiber synapse numbers. Using systematic analyses of all neuroligins in a defined neural circuit, our data thus show that neuroligins differentially contribute to various Purkinje-cell synapses in the cerebellum in vivo.
ESTHER : Zhang_2015_Neuron_87_781
PubMedSearch : Zhang_2015_Neuron_87_781
PubMedID: 26291161

Title : Cartography of neurexin alternative splicing mapped by single-molecule long-read mRNA sequencing - Treutlein_2014_Proc.Natl.Acad.Sci.U.S.A_111_E1291
Author(s) : Treutlein B , Gokce O , Quake SR , Sudhof TC
Ref : Proc Natl Acad Sci U S A , 111 :E1291 , 2014
Abstract : Neurexins are evolutionarily conserved presynaptic cell-adhesion molecules that are essential for normal synapse formation and synaptic transmission. Indirect evidence has indicated that extensive alternative splicing of neurexin mRNAs may produce hundreds if not thousands of neurexin isoforms, but no direct evidence for such diversity has been available. Here we use unbiased long-read sequencing of full-length neurexin (Nrxn)1alpha, Nrxn1beta, Nrxn2beta, Nrxn3alpha, and Nrxn3beta mRNAs to systematically assess how many sites of alternative splicing are used in neurexins with a significant frequency, and whether alternative splicing events at these sites are independent of each other. In sequencing more than 25,000 full-length mRNAs, we identified a novel, abundantly used alternatively spliced exon of Nrxn1alpha and Nrxn3alpha (referred to as alternatively spliced sequence 6) that encodes a 9-residue insertion in the flexible hinge region between the fifth LNS (laminin-alpha, neurexin, sex hormone-binding globulin) domain and the third EGF-like sequence. In addition, we observed several larger-scale events of alternative splicing that deleted multiple domains and were much less frequent than the canonical six sites of alternative splicing in neurexins. All of the six canonical events of alternative splicing appear to be independent of each other, suggesting that neurexins may exhibit an even larger isoform diversity than previously envisioned and comprise thousands of variants. Our data are consistent with the notion that alpha-neurexins represent extracellular protein-interaction scaffolds in which different LNS and EGF domains mediate distinct interactions that affect diverse functions and are independently regulated by independent events of alternative splicing.
ESTHER : Treutlein_2014_Proc.Natl.Acad.Sci.U.S.A_111_E1291
PubMedSearch : Treutlein_2014_Proc.Natl.Acad.Sci.U.S.A_111_E1291
PubMedID: 24639501

Title : Direct Visualization of Trans-Synaptic Neurexin-Neuroligin Interactions during Synapse Formation - Tsetsenis_2014_J.Neurosci_34_15083
Author(s) : Tsetsenis T , Boucard AA , Arac D , Brunger AT , Sudhof TC
Ref : Journal of Neuroscience , 34 :15083 , 2014
Abstract : Neurexins and neuroligins are synaptic cell-adhesion molecules that are essential for normal synapse specification and function and are thought to bind to each other trans-synaptically, but such interactions have not been demonstrated directly. Here, we generated neurexin-1beta and neuroligin-1 and neuroligin-2 fusion proteins containing complementary "split" GFP fragments positioned such that binding of neurexin-1beta to neuroligin-1 or neuroligin-2 allowed GFP reconstitution without dramatically changing their binding affinities. GFP fluorescence was only reconstituted from split-GFP-modified neurexin-1beta and neuroligin-1 if and after neurexin-1beta bound to its neuroligin partner; reassociation of the split-GFP components with each other did not mediate binding. Using trans-cellular reconstitution of GFP fluorescence from split-GFP-modified neurexin-1beta and neuroligins as an assay, we demonstrate that trans-synaptic neurexin/neuroligin binding indeed occurred when mouse hippocampal neurons formed synapses onto non-neuronal COS-7 cells expressing neuroligins or when mouse hippocampal neurons formed synapses with each other. This visualization of synapses by neurexin/neuroligin binding prompted us to refer to this approach as "SynView." Our data demonstrate that neurexin-1beta forms a trans-synaptic complex with neuroligin-1 and neuroligin-2 and that this interaction can be used to label synapses in a specific fashion in vivo.
ESTHER : Tsetsenis_2014_J.Neurosci_34_15083
PubMedSearch : Tsetsenis_2014_J.Neurosci_34_15083
PubMedID: 25378172

Title : Autism-associated neuroligin-3 mutations commonly impair striatal circuits to boost repetitive behaviors - Rothwell_2014_Cell_158_198
Author(s) : Rothwell PE , Fuccillo MV , Maxeiner S , Hayton SJ , Gokce O , Lim BK , Fowler SC , Malenka RC , Sudhof TC
Ref : Cell , 158 :198 , 2014
Abstract : In humans, neuroligin-3 mutations are associated with autism, whereas in mice, the corresponding mutations produce robust synaptic and behavioral changes. However, different neuroligin-3 mutations cause largely distinct phenotypes in mice, and no causal relationship links a specific synaptic dysfunction to a behavioral change. Using rotarod motor learning as a proxy for acquired repetitive behaviors in mice, we found that different neuroligin-3 mutations uniformly enhanced formation of repetitive motor routines. Surprisingly, neuroligin-3 mutations caused this phenotype not via changes in the cerebellum or dorsal striatum but via a selective synaptic impairment in the nucleus accumbens/ventral striatum. Here, neuroligin-3 mutations increased rotarod learning by specifically impeding synaptic inhibition onto D1-dopamine receptor-expressing but not D2-dopamine receptor-expressing medium spiny neurons. Our data thus suggest that different autism-associated neuroligin-3 mutations cause a common increase in acquired repetitive behaviors by impairing a specific striatal synapse and thereby provide a plausible circuit substrate for autism pathophysiology. PAPERFLICK:
ESTHER : Rothwell_2014_Cell_158_198
PubMedSearch : Rothwell_2014_Cell_158_198
PubMedID: 24995986

Title : Membrane-Tethered Monomeric Neurexin LNS-Domain Triggers Synapse Formation - Gokce_2013_J.Neurosci_33_14617
Author(s) : Gokce O , Sudhof TC
Ref : Journal of Neuroscience , 33 :14617 , 2013
Abstract : Neurexins are presynaptic cell-adhesion molecules that bind to postsynaptic cell-adhesion molecules such as neuroligins and leucine-rich repeat transmembrane proteins (LRRTMs). When neuroligins or LRRTMs are expressed in a nonneuronal cell, cocultured neurons avidly form heterologous synapses onto that cell. Here we show that knockdown of all neurexins in cultured hippocampal mouse neurons did not impair synapse formation between neurons, but blocked heterologous synapse formation induced by neuroligin-1 or LRRTM2. Rescue experiments demonstrated that all neurexins tested restored heterologous synapse formation in neurexin-deficient neurons. Neurexin-deficient neurons exhibited a decrease in the levels of the PDZ-domain protein CASK (a calcium/calmodulin-activated serine/threonine kinase), which binds to neurexins, and mutation of the PDZ-domain binding sequence of neurexin-3beta blocked its transport to the neuronal surface and impaired heterologous synapse formation. However, replacement of the C-terminal neurexin sequence with an unrelated PDZ-domain binding sequence that does not bind to CASK fully restored surface transport and heterologous synapse formation in neurexin-deficient neurons, suggesting that no particular PDZ-domain protein is essential for neurexin surface transport or heterologous synapse formation. Further mutagenesis revealed, moreover, that the entire neurexin cytoplasmic tail was dispensable for heterologous synapse formation in neurexin-deficient neurons, as long as the neurexin protein was transported to the neuronal cell surface. Furthermore, the single LNS-domain (for laminin/neurexin/sex hormone-binding globulin-domain) of neurexin-1beta or neurexin-3beta, when tethered to the presynaptic plasma membrane by a glycosylinositolphosphate anchor, was sufficient for rescuing heterologous synapse formation in neurexin-deficient neurons. Our data suggest that neurexins mediate heterologous synapse formation via an extracellular interaction with presynaptic and postsynaptic ligands without the need for signal transduction by the neurexin cytoplasmic tail.
ESTHER : Gokce_2013_J.Neurosci_33_14617
PubMedSearch : Gokce_2013_J.Neurosci_33_14617
PubMedID: 24005312

Title : Neurons generated by direct conversion of fibroblasts reproduce synaptic phenotype caused by autism-associated neuroligin-3 mutation - Chanda_2013_Proc.Natl.Acad.Sci.U.S.A_110_16622
Author(s) : Chanda S , Marro S , Wernig M , Sudhof TC
Ref : Proc Natl Acad Sci U S A , 110 :16622 , 2013
Abstract : Recent studies suggest that induced neuronal (iN) cells that are directly transdifferentiated from nonneuronal cells provide a powerful opportunity to examine neuropsychiatric diseases. However, the validity of using this approach to examine disease-specific changes has not been demonstrated. Here, we analyze the phenotypes of iN cells that were derived from murine embryonic fibroblasts cultured from littermate wild-type and mutant mice carrying the autism-associated R704C substitution in neuroligin-3. We show that neuroligin-3 R704C-mutant iN cells exhibit a large and selective decrease in AMPA-type glutamate receptor-mediated synaptic transmission without changes in NMDA-type glutamate receptor- or in GABAA receptor-mediated synaptic transmission. Thus, the synaptic phenotype observed in R704C-mutant iN cells replicates the previously observed phenotype of R704C-mutant neurons. Our data show that the effect of the R704C mutation is applicable even to neurons transdifferentiated from fibroblasts and constitute a proof-of-concept demonstration that iN cells can be used for cellular disease modeling.
ESTHER : Chanda_2013_Proc.Natl.Acad.Sci.U.S.A_110_16622
PubMedSearch : Chanda_2013_Proc.Natl.Acad.Sci.U.S.A_110_16622
PubMedID: 24046374

Title : Autism-associated neuroligin-3 mutations commonly disrupt tonic endocannabinoid signaling - Foldy_2013_Neuron_78_498
Author(s) : Foldy C , Malenka RC , Sudhof TC
Ref : Neuron , 78 :498 , 2013
Abstract : Neuroligins are postsynaptic cell-adhesion molecules that interact with presynaptic neurexins. Rare mutations in neuroligins and neurexins predispose to autism, including a neuroligin-3 amino acid substitution (R451C) and a neuroligin-3 deletion. Previous analyses showed that neuroligin-3 R451C-knockin mice exhibit robust synaptic phenotypes but failed to uncover major changes in neuroligin-3 knockout mice, questioning the notion that a common synaptic mechanism mediates autism pathogenesis in patients with these mutations. Here, we used paired recordings in mice carrying these mutations to measure synaptic transmission at GABAergic synapses formed by hippocampal parvalbumin- and cholecystokinin-expressing basket cells onto pyramidal neurons. We demonstrate that in addition to unique gain-of-function effects produced by the neuroligin-3 R451C-knockin but not the neuroligin-3 knockout mutation, both mutations dramatically impaired tonic but not phasic endocannabinoid signaling. Our data thus suggest that neuroligin-3 is specifically required for tonic endocannabinoid signaling, raising the possibility that alterations in endocannabinoid signaling may contribute to autism pathophysiology.
ESTHER : Foldy_2013_Neuron_78_498
PubMedSearch : Foldy_2013_Neuron_78_498
PubMedID: 23583622

Title : MDGAs interact selectively with neuroligin-2 but not other neuroligins to regulate inhibitory synapse development - Lee_2013_Proc.Natl.Acad.Sci.U.S.A_110_336
Author(s) : Lee K , Kim Y , Lee SJ , Qiang Y , Lee D , Lee HW , Kim H , Je HS , Sudhof TC , Ko J
Ref : Proc Natl Acad Sci U S A , 110 :336 , 2013
Abstract : The MAM domain-containing GPI anchor proteins MDGA1 and MDGA2 are Ig superfamily adhesion molecules composed of six IG domains, a fibronectin III domain, a MAM domain, and a GPI anchor. MDGAs contribute to the radial migration and positioning of a subset of cortical neurons during early neural development. However, MDGAs continue to be expressed in postnatal brain, and their functions during postnatal neural development remain unknown. Here, we demonstrate that MDGAs specifically and with a nanomolar affinity bind to neuroligin-2, a cell-adhesion molecule of inhibitory synapses, but do not bind detectably to neuroligin-1 or neuroligin-3. We observed no cell adhesion between cells expressing neuroligin-2 and MDGA1, suggesting a cis interaction. Importantly, RNAi-mediated knockdown of MDGAs increased the abundance of inhibitory but not excitatory synapses in a neuroligin-2-dependent manner. Conversely, overexpression of MDGA1 decreased the numbers of functional inhibitory synapses. Likewise, coexpression of both MDGA1 and neuroligin-2 reduced the synaptogenic capacity of neuroligin-2 in an artificial synapse-formation assay by abolishing the ability of neuroligin-2 to form an adhesion complex with neurexins. Taken together, our data suggest that MDGAs inhibit the activity of neuroligin-2 in controlling the function of inhibitory synapses and that MDGAs do so by binding to neuroligin-2.
ESTHER : Lee_2013_Proc.Natl.Acad.Sci.U.S.A_110_336
PubMedSearch : Lee_2013_Proc.Natl.Acad.Sci.U.S.A_110_336
PubMedID: 23248271

Title : An autism-associated point mutation in the neuroligin cytoplasmic tail selectively impairs AMPA receptor-mediated synaptic transmission in hippocampus - Etherton_2011_EMBO.J_30_2908
Author(s) : Etherton MR , Tabuchi K , Sharma M , Ko J , Sudhof TC
Ref : EMBO Journal , 30 :2908 , 2011
Abstract : Neuroligins are evolutionarily conserved postsynaptic cell-adhesion molecules that function, at least in part, by forming trans-synaptic complexes with presynaptic neurexins. Different neuroligin isoforms perform diverse functions and exhibit distinct intracellular localizations, but contain similar cytoplasmic sequences whose role remains largely unknown. Here, we analysed the effect of a single amino-acid substitution (R704C) that targets a conserved arginine residue in the cytoplasmic sequence of all neuroligins, and that was associated with autism in neuroligin-4. We introduced the R704C mutation into mouse neuroligin-3 by homologous recombination, and examined its effect on synapses in vitro and in vivo. Electrophysiological and morphological studies revealed that the neuroligin-3 R704C mutation did not significantly alter synapse formation, but dramatically impaired synapse function. Specifically, the R704C mutation caused a major and selective decrease in AMPA receptor-mediated synaptic transmission in pyramidal neurons of the hippocampus, without similarly changing NMDA or GABA receptor-mediated synaptic transmission, and without detectably altering presynaptic neurotransmitter release. Our results suggest that the cytoplasmic tail of neuroligin-3 has a central role in synaptic transmission by modulating the recruitment of AMPA receptors to postsynaptic sites at excitatory synapses.
ESTHER : Etherton_2011_EMBO.J_30_2908
PubMedSearch : Etherton_2011_EMBO.J_30_2908
PubMedID: 21642956

Title : Autism-linked neuroligin-3 R451C mutation differentially alters hippocampal and cortical synaptic function - Etherton_2011_Proc.Natl.Acad.Sci.U.S.A_108_13764
Author(s) : Etherton M , Foldy C , Sharma M , Tabuchi K , Liu X , Shamloo M , Malenka RC , Sudhof TC
Ref : Proc Natl Acad Sci U S A , 108 :13764 , 2011
Abstract : Multiple independent mutations in neuroligin genes were identified in patients with familial autism, including the R451C substitution in neuroligin-3 (NL3). Previous studies showed that NL3(R451C) knock-in mice exhibited modestly impaired social behaviors, enhanced water maze learning abilities, and increased synaptic inhibition in the somatosensory cortex, and they suggested that the behavioral changes in these mice may be caused by a general shift of synaptic transmission to inhibition. Here, we confirm that NL3(R451C) mutant mice behaviorally exhibit social interaction deficits and electrophysiologically display increased synaptic inhibition in the somatosensory cortex. Unexpectedly, however, we find that the NL3(R451C) mutation produced a strikingly different phenotype in the hippocampus. Specifically, in the hippocampal CA1 region, the NL3(R451C) mutation caused an approximately 1.5-fold increase in AMPA receptor-mediated excitatory synaptic transmission, dramatically altered the kinetics of NMDA receptor-mediated synaptic responses, induced an approximately twofold up-regulation of NMDA receptors containing NR2B subunits, and enhanced long-term potentiation almost twofold. NL3 KO mice did not exhibit any of these changes. Quantitative light microscopy and EM revealed that the NL3(R451C) mutation increased dendritic branching and altered the structure of synapses in the stratum radiatum of the hippocampus. Thus, in NL3(R451C) mutant mice, a single point mutation in a synaptic cell adhesion molecule causes context-dependent changes in synaptic transmission; these changes are consistent with the broad impact of this mutation on murine and human behaviors, suggesting that NL3 controls excitatory and inhibitory synapse properties in a region- and circuit-specific manner.
ESTHER : Etherton_2011_Proc.Natl.Acad.Sci.U.S.A_108_13764
PubMedSearch : Etherton_2011_Proc.Natl.Acad.Sci.U.S.A_108_13764
PubMedID: 21808020
Gene_locus related to this paper: human-NLGN3

Title : Neuroligin-1 deletion results in impaired spatial memory and increased repetitive behavior - Blundell_2010_J.Neurosci_30_2115
Author(s) : Blundell J , Blaiss CA , Etherton MR , Espinosa F , Tabuchi K , Walz C , Bolliger MF , Sudhof TC , Powell CM
Ref : Journal of Neuroscience , 30 :2115 , 2010
Abstract : Neuroligins (NLs) are a family of neural cell-adhesion molecules that are involved in excitatory/inhibitory synapse specification. Multiple members of the NL family (including NL1) and their binding partners have been linked to cases of human autism and mental retardation. We have now characterized NL1-deficient mice in autism- and mental retardation-relevant behavioral tasks. NL1 knock-out (KO) mice display deficits in spatial learning and memory that correlate with impaired hippocampal long-term potentiation. In addition, NL1 KO mice exhibit a dramatic increase in repetitive, stereotyped grooming behavior, a potential autism-relevant abnormality. This repetitive grooming abnormality in NL1 KO mice is associated with a reduced NMDA/AMPA ratio at corticostriatal synapses. Interestingly, we further demonstrate that the increased repetitive grooming phenotype can be rescued in adult mice by administration of the NMDA receptor partial coagonist d-cycloserine. Broadly, these data are consistent with a role of synaptic cell-adhesion molecules in general, and NL1 in particular, in autism and implicate reduced excitatory synaptic transmission as a potential mechanism and treatment target for repetitive behavioral abnormalities.
ESTHER : Blundell_2010_J.Neurosci_30_2115
PubMedSearch : Blundell_2010_J.Neurosci_30_2115
PubMedID: 20147539

Title : Neurexins physically and functionally interact with GABA(A) receptors - Zhang_2010_Neuron_66_403
Author(s) : Zhang C , Atasoy D , Arac D , Yang X , Fucillo MV , Robison AJ , Ko J , Brunger AT , Sudhof TC
Ref : Neuron , 66 :403 , 2010
Abstract : Neurexins are presynaptic cell-adhesion molecules that form trans-synaptic complexes with postsynaptic neuroligins. When overexpressed in nonneuronal cells, neurexins induce formation of postsynaptic specializations in cocultured neurons, suggesting that neurexins are synaptogenic. However, we find that when overexpressed in neurons, neurexins do not increase synapse density, but instead selectively suppressed GABAergic synaptic transmission without decreasing GABAergic synapse numbers. This suppression was mediated by all subtypes of neurexins tested, in a cell-autonomous and neuroligin-independent manner. Strikingly, addition of recombinant neurexin to cultured neurons at submicromolar concentrations induced the same suppression of GABAergic synaptic transmission as neurexin overexpression. Moreover, experiments with native brain proteins and purified recombinant proteins revealed that neurexins directly and stoichiometrically bind to GABA(A) receptors, suggesting that they decrease GABAergic synaptic responses by interacting with GABA(A) receptors. Our findings suggest that besides their other well-documented interactions, presynaptic neurexins directly act on postsynaptic GABA(A) receptors, which may contribute to regulate the excitatory/inhibitory balance in brain.
ESTHER : Zhang_2010_Neuron_66_403
PubMedSearch : Zhang_2010_Neuron_66_403
PubMedID: 20471353

Title : LRRTM2 functions as a neurexin ligand in promoting excitatory synapse formation - Ko_2009_Neuron_64_791
Author(s) : Ko J , Fuccillo MV , Malenka RC , Sudhof TC
Ref : Neuron , 64 :791 , 2009
Abstract : Recently, leucine-rich repeat transmembrane proteins (LRRTMs) were found to be synaptic cell-adhesion molecules that, when expressed in nonneuronal cells, induce presynaptic differentiation in contacting axons. We now demonstrate that LRRTM2 induces only excitatory synapses, and that it also acts to induce synapses in transfected neurons similarly to neuroligin-1. Using affinity chromatography, we identified alpha- and beta-neurexins as LRRTM2 ligands, again rendering LRRTM2 similar to neuroligin-1. However, whereas neuroligins bind neurexins containing or lacking an insert in splice site #4, LRRTM2 only binds neurexins lacking an insert in splice site #4. Binding of neurexins to LRRTM2 can produce cell-adhesion junctions, consistent with a trans-interaction regulated by neurexin alternative splicing, and recombinant neurexin-1beta blocks LRRTM2's ability to promote presynaptic differentiation. Thus, our data suggest that two unrelated postsynaptic cell-adhesion molecules, LRRTMs and neuroligins, unexpectedly bind to neurexins as the same presynaptic receptor, but that their binding is subject to distinct regulatory mechanisms.
ESTHER : Ko_2009_Neuron_64_791
PubMedSearch : Ko_2009_Neuron_64_791
PubMedID: 20064387

Title : Increased anxiety-like behavior in mice lacking the inhibitory synapse cell adhesion molecule neuroligin 2 - Blundell_2009_Genes.Brain.Behav_8_114
Author(s) : Blundell J , Tabuchi K , Bolliger MF , Blaiss CA , Brose N , Liu X , Sudhof TC , Powell CM
Ref : Genes Brain Behav , 8 :114 , 2009
Abstract : Neuroligins (NL) are postsynaptic cell adhesion molecules that are thought to specify synapse properties. Previous studies showed that mutant mice carrying an autism-associated point mutation in NL3 exhibit social interaction deficits, enhanced inhibitory synaptic function and increased staining of inhibitory synaptic puncta without changes in overall inhibitory synapse numbers. In contrast, mutant mice lacking NL2 displayed decreased inhibitory synaptic function. These studies raised two relevant questions. First, does NL2 deletion impair inhibitory synaptic function by altering the number of inhibitory synapses, or by changing their efficacy? Second, does this effect of NL2 deletion on inhibition produce behavioral changes? We now show that although NL2-deficient mice exhibit an apparent decrease in number of inhibitory synaptic puncta, the number of symmetric synapses as determined by electron microscopy is unaltered, suggesting that NL2 deletion impairs the function of inhibitory synapses without decreasing their numbers. This decrease in inhibitory synaptic function in NL2-deficient mice correlates with a discrete behavioral phenotype that includes a marked increase in anxiety-like behavior, a decrease in pain sensitivity and a slight decrease in motor co-ordination. This work confirms that NL2 modulates inhibitory synaptic function and is the first demonstration that global deletion of NL2 can lead to a selective behavioral phenotype.
ESTHER : Blundell_2009_Genes.Brain.Behav_8_114
PubMedSearch : Blundell_2009_Genes.Brain.Behav_8_114
PubMedID: 19016888

Title : Common circuit defect of excitatory-inhibitory balance in mouse models of autism - Gogolla_2009_J.Neurodev.Disord_1_172
Author(s) : Gogolla N , Leblanc JJ , Quast KB , Sudhof TC , Fagiolini M , Hensch TK
Ref : J Neurodev Disord , 1 :172 , 2009
Abstract : One unifying explanation for the complexity of Autism Spectrum Disorders (ASD) may lie in the disruption of excitatory/inhibitory (E/I) circuit balance during critical periods of development. We examined whether Parvalbumin (PV)-positive inhibitory neurons, which normally drive experience-dependent circuit refinement (Hensch Nat Rev Neurosci 6:877-888, 1), are disrupted across heterogeneous ASD mouse models. We performed a meta-analysis of PV expression in previously published ASD mouse models and analyzed two additional models, reflecting an embryonic chemical insult (prenatal valproate, VPA) or single-gene mutation identified in human patients (Neuroligin-3, NL-3 R451C). PV-cells were reduced in the neocortex across multiple ASD mouse models. In striking contrast to controls, both VPA and NL-3 mouse models exhibited an asymmetric PV-cell reduction across hemispheres in parietal and occipital cortices (but not the underlying area CA1). ASD mouse models may share a PV-circuit disruption, providing new insight into circuit development and potential prevention by treatment of autism.
ESTHER : Gogolla_2009_J.Neurodev.Disord_1_172
PubMedSearch : Gogolla_2009_J.Neurodev.Disord_1_172
PubMedID: 20664807

Title : A neuroligin-4 missense mutation associated with autism impairs neuroligin-4 folding and endoplasmic reticulum export - Zhang_2009_J.Neurosci_29_10843
Author(s) : Zhang C , Milunsky JM , Newton S , Ko J , Zhao G , Maher TA , Tager-Flusberg H , Bolliger MF , Carter AS , Boucard AA , Powell CM , Sudhof TC
Ref : Journal of Neuroscience , 29 :10843 , 2009
Abstract : Neuroligins (NLs) are postsynaptic cell-adhesion molecules essential for normal synapse function. Mutations in neuroligin-4 (NL4) (gene symbol: NLGN4) have been reported in some patients with autism spectrum disorder (ASD) and other neurodevelopmental impairments. However, the low frequency of NL4 mutations and the limited information about the affected patients and the functional consequences of their mutations cast doubt on the causal role of NL4 mutations in these disorders. Here, we describe two brothers with classical ASD who carry a single amino-acid substitution in NL4 (R87W). This substitution was absent from the brothers' asymptomatic parents, suggesting that it arose in the maternal germ line. R87 is conserved in all NL isoforms, and the R87W substitution is not observed in control individuals. At the protein level, the R87W substitution impaired glycosylation processing of NL4 expressed in HEK293 and COS cells, destabilized NL4, caused NL4 retention in the endoplasmic reticulum in non-neuronal cells and neurons, and blocked NL4 transport to the cell surface. As a result, the R87W substitution inactivated the synapse-formation activity of NL4 and abolished the functional effect of NL4 on synapse strength. Viewed together, these observations suggest that a point mutation in NL4 can cause ASD by a loss-of-function mechanism.
ESTHER : Zhang_2009_J.Neurosci_29_10843
PubMedSearch : Zhang_2009_J.Neurosci_29_10843
PubMedID: 19726642

Title : Neuroligin-2 deletion selectively decreases inhibitory synaptic transmission originating from fast-spiking but not from somatostatin-positive interneurons - Gibson_2009_J.Neurosci_29_13883
Author(s) : Gibson JR , Huber KM , Sudhof TC
Ref : Journal of Neuroscience , 29 :13883 , 2009
Abstract : Neuroligins are cell adhesion molecules involved in synapse formation and/or function. Neurons express four neuroligins (NL1-NL4), of which NL1 is specific to excitatory and NL2 to inhibitory synapses. Excitatory and inhibitory synapses include numerous subtypes. However, it is unknown whether NL1 performs similar functions in all excitatory and NL2 in all inhibitory synapses, or whether they regulate the formation and/or function of specific subsets of synapses. To address this central question, we performed paired recordings in primary somatosensory cortex of mice lacking NL1 or NL2. Using this system, we examined neocortical microcircuits formed by reciprocal synapses between excitatory neurons and two subtypes of inhibitory interneurons, namely, fast-spiking and somatostatin-positive interneurons. We find that the NL1 deletion had little effect on inhibitory synapses, whereas the NL2 deletion decreased (40-50%) the unitary (cell-to-cell) IPSC amplitude evoked from single fast-spiking interneurons. Strikingly, the NL2 deletion had no effect on IPSC amplitude evoked from single somatostatin-positive inhibitory interneurons. Moreover, the frequency of unitary synaptic connections between individual fast-spiking and somatostatin-positive interneurons and excitatory neurons was unchanged. The decrease in unitary IPSC amplitude originating from fast-spiking interneurons in NL2-deficient mice was due to a multiplicative and uniform downscaling of the amplitude distribution, which in turn was mediated by a decrease in both synaptic quantal amplitude and quantal content, the latter inferred from an increase in the coefficient of variation. Thus, NL2 is not necessary for establishing unitary inhibitory synaptic connections but is selectively required for "scaling up" unitary connections originating from a subset of interneurons.
ESTHER : Gibson_2009_J.Neurosci_29_13883
PubMedSearch : Gibson_2009_J.Neurosci_29_13883
PubMedID: 19889999

Title : Neuroligin-1 performs neurexin-dependent and neurexin-independent functions in synapse validation - Ko_2009_Embo.J_28_3244
Author(s) : Ko J , Zhang C , Arac D , Boucard AA , Brunger AT , Sudhof TC
Ref : EMBO Journal , 28 :3244 , 2009
Abstract : Postsynaptic neuroligins are thought to perform essential functions in synapse validation and synaptic transmission by binding to, and dimerizing, presynaptic alpha- and beta-neurexins. To test this hypothesis, we examined the functional effects of neuroligin-1 mutations that impair only alpha-neurexin binding, block both alpha- and beta-neurexin binding, or abolish neuroligin-1 dimerization. Abolishing alpha-neurexin binding abrogated neuroligin-induced generation of neuronal synapses onto transfected non-neuronal cells in the so-called artificial synapse-formation assay, even though beta-neurexin binding was retained. Thus, in this assay, neuroligin-1 induces apparent synapse formation by binding to presynaptic alpha-neurexins. In transfected neurons, however, neither alpha- nor beta-neurexin binding was essential for the ability of postsynaptic neuroligin-1 to dramatically increase synapse density, suggesting a neurexin-independent mechanism of synapse formation. Moreover, neuroligin-1 dimerization was not required for either the non-neuronal or the neuronal synapse-formation assay. Nevertheless, both alpha-neurexin binding and neuroligin-1 dimerization were essential for the increase in apparent synapse size that is induced by neuroligin-1 in transfected neurons. Thus, neuroligin-1 performs diverse synaptic functions by mechanisms that include as essential components of alpha-neurexin binding and neuroligin dimerization, but extend beyond these activities.
ESTHER : Ko_2009_Embo.J_28_3244
PubMedSearch : Ko_2009_Embo.J_28_3244
PubMedID: 19730411
Gene_locus related to this paper: ratno-1neur

Title : Neuroligins and neurexins link synaptic function to cognitive disease - Sudhof_2008_Nature_455_903
Author(s) : Sudhof TC
Ref : Nature , 455 :903 , 2008
Abstract : The brain processes information by transmitting signals at synapses, which connect neurons into vast networks of communicating cells. In these networks, synapses not only transmit signals but also transform and refine them. Neurexins and neuroligins are synaptic cell-adhesion molecules that connect presynaptic and postsynaptic neurons at synapses, mediate signalling across the synapse, and shape the properties of neural networks by specifying synaptic functions. In humans, alterations in genes encoding neurexins or neuroligins have recently been implicated in autism and other cognitive diseases, linking synaptic cell adhesion to cognition and its disorders.
ESTHER : Sudhof_2008_Nature_455_903
PubMedSearch : Sudhof_2008_Nature_455_903
PubMedID: 18923512

Title : Unusually rapid evolution of Neuroligin-4 in mice - Bolliger_2008_Proc.Natl.Acad.Sci.U.S.A_105_6421
Author(s) : Bolliger MF , Pei J , Maxeiner S , Boucard AA , Grishin NV , Sudhof TC
Ref : Proc Natl Acad Sci U S A , 105 :6421 , 2008
Abstract : Neuroligins (NLs) are postsynaptic cell-adhesion molecules that are implicated in humans in autism spectrum disorders because the genes encoding NL3 and NL4 are mutated in rare cases of familial autism. NLs are highly conserved evolutionarily, except that no NL4 was detected in the currently available mouse genome sequence assemblies. We now demonstrate that mice express a distant NL4 variant that rapidly evolved from other mammalian NL4 genes and that exhibits sequence variations even between different mouse strains. Despite its divergence, mouse NL4 binds neurexins and is transported into dendritic spines, suggesting that the core properties of NLs are retained in this divergent NL isoform. The selectively rapid evolution of NL4 in mice suggests that its function in the brain is under less stringent control than that of other NLs, shedding light on why its mutation in autism spectrum disorder patients is not lethal, but instead leads to a discrete developmental brain disorder.
ESTHER : Bolliger_2008_Proc.Natl.Acad.Sci.U.S.A_105_6421
PubMedSearch : Bolliger_2008_Proc.Natl.Acad.Sci.U.S.A_105_6421
PubMedID: 18434543
Gene_locus related to this paper: mouse-4neur

Title : Activity-dependent validation of excitatory versus inhibitory synapses by neuroligin-1 versus neuroligin-2 - Chubykin_2007_Neuron_54_919
Author(s) : Chubykin AA , Atasoy D , Etherton MR , Brose N , Kavalali ET , Gibson JR , Sudhof TC
Ref : Neuron , 54 :919 , 2007
Abstract : Neuroligins enhance synapse formation in vitro, but surprisingly are not required for the generation of synapses in vivo. We now show that in cultured neurons, neuroligin-1 overexpression increases excitatory, but not inhibitory, synaptic responses, and potentiates synaptic NMDAR/AMPAR ratios. In contrast, neuroligin-2 overexpression increases inhibitory, but not excitatory, synaptic responses. Accordingly, deletion of neuroligin-1 in knockout mice selectively decreases the NMDAR/AMPAR ratio, whereas deletion of neuroligin-2 selectively decreases inhibitory synaptic responses. Strikingly, chronic inhibition of NMDARs or CaM-Kinase II, which signals downstream of NMDARs, suppresses the synapse-boosting activity of neuroligin-1, whereas chronic inhibition of general synaptic activity suppresses the synapse-boosting activity of neuroligin-2. Taken together, these data indicate that neuroligins do not establish, but specify and validate, synapses via an activity-dependent mechanism, with different neuroligins acting on distinct types of synapses. This hypothesis reconciles the overexpression and knockout phenotypes and suggests that neuroligins contribute to the use-dependent formation of neural circuits.
ESTHER : Chubykin_2007_Neuron_54_919
PubMedSearch : Chubykin_2007_Neuron_54_919
PubMedID: 17582332

Title : Deletion of CASK in mice is lethal and impairs synaptic function - Atasoy_2007_Proc.Natl.Acad.Sci.U.S.A_104_2525
Author(s) : Atasoy D , Schoch S , Ho A , Nadasy KA , Liu X , Zhang W , Mukherjee K , Nosyreva ED , Fernandez-Chacon R , Missler M , Kavalali ET , Sudhof TC
Ref : Proc Natl Acad Sci U S A , 104 :2525 , 2007
Abstract : CASK is an evolutionarily conserved multidomain protein composed of an N-terminal Ca2+/calmodulin-kinase domain, central PDZ and SH3 domains, and a C-terminal guanylate kinase domain. Many potential activities for CASK have been suggested, including functions in scaffolding the synapse, in organizing ion channels, and in regulating neuronal gene transcription. To better define the physiological importance of CASK, we have now analyzed CASK "knockdown" mice in which CASK expression was suppressed by approximately 70%, and CASK knockout (KO) mice, in which CASK expression was abolished. CASK knockdown mice are viable but smaller than WT mice, whereas CASK KO mice die at first day after birth. CASK KO mice exhibit no major developmental abnormalities apart from a partially penetrant cleft palate syndrome. In CASK-deficient neurons, the levels of the CASK-interacting proteins Mints, Veli/Mals, and neurexins are decreased, whereas the level of neuroligin 1 (which binds to neurexins that in turn bind to CASK) is increased. Neurons lacking CASK display overall normal electrical properties and form ultrastructurally normal synapses. However, glutamatergic spontaneous synaptic release events are increased, and GABAergic synaptic release events are decreased in CASK-deficient neurons. In contrast to spontaneous neurotransmitter release, evoked release exhibited no major changes. Our data suggest that CASK, the only member of the membrane-associated guanylate kinase protein family that contains a Ca2+/calmodulin-dependent kinase domain, is required for mouse survival and performs a selectively essential function without being in itself required for core activities of neurons, such as membrane excitability, Ca2+-triggered presynaptic release, or postsynaptic receptor functions.
ESTHER : Atasoy_2007_Proc.Natl.Acad.Sci.U.S.A_104_2525
PubMedSearch : Atasoy_2007_Proc.Natl.Acad.Sci.U.S.A_104_2525
PubMedID: 17287346

Title : A neuroligin-3 mutation implicated in autism increases inhibitory synaptic transmission in mice - Tabuchi_2007_Science_318_71
Author(s) : Tabuchi K , Blundell J , Etherton MR , Hammer RE , Liu X , Powell CM , Sudhof TC
Ref : Science , 318 :71 , 2007
Abstract : Autism spectrum disorders (ASDs) are characterized by impairments in social behaviors that are sometimes coupled to specialized cognitive abilities. A small percentage of ASD patients carry mutations in genes encoding neuroligins, which are postsynaptic cell-adhesion molecules. We introduced one of these mutations into mice: the Arg451-->Cys451 (R451C) substitution in neuroligin-3. R451C mutant mice showed impaired social interactions but enhanced spatial learning abilities. Unexpectedly, these behavioral changes were accompanied by an increase in inhibitory synaptic transmission with no apparent effect on excitatory synapses. Deletion of neuroligin-3, in contrast, did not cause such changes, indicating that the R451C substitution represents a gain-of-function mutation. These data suggest that increased inhibitory synaptic transmission may contribute to human ASDs and that the R451C knockin mice may be a useful model for studying autism-related behaviors.
ESTHER : Tabuchi_2007_Science_318_71
PubMedSearch : Tabuchi_2007_Science_318_71
PubMedID: 17823315
Gene_locus related to this paper: human-NLGN3 , human-NLGN4X

Title : Structures of neuroligin-1 and the neuroligin-1\/neurexin-1 beta complex reveal specific protein-protein and protein-Ca2+ interactions - Arac_2007_Neuron_56_992
Author(s) : Arac D , Boucard AA , Ozkan E , Strop P , Newell E , Sudhof TC , Brunger AT
Ref : Neuron , 56 :992 , 2007
Abstract : Neurexins and neuroligins provide trans-synaptic connectivity by the Ca2+-dependent interaction of their alternatively spliced extracellular domains. Neuroligins specify synapses in an activity-dependent manner, presumably by binding to neurexins. Here, we present the crystal structures of neuroligin-1 in isolation and in complex with neurexin-1 beta. Neuroligin-1 forms a constitutive dimer, and two neurexin-1 beta monomers bind to two identical surfaces on the opposite faces of the neuroligin-1 dimer to form a heterotetramer. The neuroligin-1/neurexin-1 beta complex exhibits a nanomolar affinity and includes a large binding interface that contains bound Ca2+. Alternatively spliced sites in neurexin-1 beta and in neuroligin-1 are positioned nearby the binding interface, explaining how they regulate the interaction. Structure-based mutations of neuroligin-1 at the interface disrupt binding to neurexin-1 beta, but not the folding of neuroligin-1 and confirm the validity of the binding interface of the neuroligin-1/neurexin-1 beta complex. Our results provide molecular insights for understanding the role of cell-adhesion proteins in synapse function.
ESTHER : Arac_2007_Neuron_56_992
PubMedSearch : Arac_2007_Neuron_56_992
PubMedID: 18093522
Gene_locus related to this paper: ratno-1neur

Title : Gene selection, alternative splicing, and post-translational processing regulate neuroligin selectivity for beta-neurexins - Comoletti_2006_Biochemistry_45_12816
Author(s) : Comoletti D , Flynn RE , Boucard AA , Demeler B , Schirf V , Shi J , Jennings LL , Newlin HR , Sudhof TC , Taylor P
Ref : Biochemistry , 45 :12816 , 2006
Abstract : Neuroligins 1-4 are postsynaptic transmembrane proteins capable of initiating presynaptic maturation via interactions with beta-neurexin. Both neuroligins and beta-neurexins have alternatively spliced inserts in their extracellular domains. Using analytical ultracentrifugation, we determined that the extracellular domains of the neuroligins sediment as dimers, whereas the extracellular domains of the beta-neurexins appear monomeric. Sedimentation velocity experiments of titrated stoichiometry ratios of beta-neurexin and neuroligin suggested a 2:2 complex formation. The recognition properties of individual neuroligins toward beta-neurexin-1 (NX1beta), along with the influence of their splice inserts, were explored by surface plasmon resonance and affinity chromatography. Different neuroligins display a range of NX1beta affinities spanning more than 2 orders of magnitude. Whereas splice insert 4 in beta-neurexin appears to act only as a modulator of the neuroligin/beta-neurexin association, splice insert B in neuroligin-1 (NL1) is the key element regulating the NL1/NX1beta binding. Our data indicate that gene selection, mRNA splicing, and post-translational modifications combine to give rise to a controlled neuroligin recognition code with a rank ordering of affinities for particular neurexins that is conserved for the neuroligins across mammalian species.
ESTHER : Comoletti_2006_Biochemistry_45_12816
PubMedSearch : Comoletti_2006_Biochemistry_45_12816
PubMedID: 17042500

Title : Neuroligins determine synapse maturation and function - Varoqueaux_2006_Neuron_51_741
Author(s) : Varoqueaux F , Aramuni G , Rawson RL , Mohrmann R , Missler M , Gottmann K , Zhang W , Sudhof TC , Brose N
Ref : Neuron , 51 :741 , 2006
Abstract : Synaptogenesis, the generation and maturation of functional synapses between nerve cells, is an essential step in the development of neuronal networks in the brain. It is thought to be triggered by members of the neuroligin family of postsynaptic cell adhesion proteins, which may form transsynaptic contacts with presynaptic alpha- and beta-neurexins and have been implicated in the etiology of autism. We show that deletion mutant mice lacking neuroligin expression die shortly after birth due to respiratory failure. This respiratory failure is a consequence of reduced GABAergic/glycinergic and glutamatergic synaptic transmission and network activity in brainstem centers that control respiration. However, the density of synaptic contacts is not altered in neuroligin-deficient brains and cultured neurons. Our data show that neuroligins are required for proper synapse maturation and brain function, but not for the initial formation of synaptic contacts.
ESTHER : Varoqueaux_2006_Neuron_51_741
PubMedSearch : Varoqueaux_2006_Neuron_51_741
PubMedID: 16982420

Title : Genetic evidence for a protein-kinase-A-mediated presynaptic component in NMDA-receptor-dependent forms of long-term synaptic potentiation - Huang_2005_Proc.Natl.Acad.Sci.U.S.A_102_9365
Author(s) : Huang YY , Zakharenko SS , Schoch S , Kaeser PS , Janz R , Sudhof TC , Siegelbaum SA , Kandel ER
Ref : Proc Natl Acad Sci U S A , 102 :9365 , 2005
Abstract : The synaptic vesicle protein Rab3A is a small GTP-binding protein that interacts with rabphilin and RIM1alpha, two presynaptic substrates of protein kinase A (PKA). Mice lacking RIM1alpha and Rab3A have a defect in PKA-dependent and NMDA receptor (NMDAR)-independent presynaptic long-term potentiation (LTP) at hippocampal mossy-fiber and cerebellar parallel-fiber synapses. In contrast, the NMDAR-dependent and PKA-independent early phase of LTP at hippocampal CA3-CA1 synapses does not require these presynaptic proteins. Here, we ask whether Rab3A and RIM1alpha participate in forms of LTP that require both PKA and NMDAR activation. We find that Rab3A is necessary for corticoamygdala LTP and late-phase LTP at CA3-CA1 synapses, two forms of LTP that require NMDAR and PKA activation. The latter form of LTP also requires RIM1alpha. These results provide genetic evidence that presynaptic proteins are required in LTP induced through the postsynaptic activation of NMDARs. Thus Rab3A and its effectors are general modules for four distinct types of PKA-dependent LTP in the brain.
ESTHER : Huang_2005_Proc.Natl.Acad.Sci.U.S.A_102_9365
PubMedSearch : Huang_2005_Proc.Natl.Acad.Sci.U.S.A_102_9365
PubMedID: 15967982

Title : A splice code for trans-synaptic cell adhesion mediated by binding of neuroligin 1 to alpha- and beta-neurexins - Boucard_2005_Neuron_48_229
Author(s) : Boucard AA , Chubykin AA , Comoletti D , Taylor P , Sudhof TC
Ref : Neuron , 48 :229 , 2005
Abstract : Previous studies suggested that postsynaptic neuroligins form a trans-synaptic complex with presynaptic beta-neurexins, but not with presynaptic alpha-neurexins. Unexpectedly, we now find that neuroligins also bind alpha-neurexins and that alpha- and beta-neurexin binding by neuroligin 1 is regulated by alternative splicing of neuroligin 1 (at splice site B) and of neurexins (at splice site 4). In neuroligin 1, splice site B is a master switch that determines alpha-neurexin binding but leaves beta-neurexin binding largely unaffected, whereas alternative splicing of neurexins modulates neuroligin binding. Moreover, neuroligin 1 splice variants with distinct neurexin binding properties differentially regulate synaptogenesis: neuroligin 1 that binds only beta-neurexins potently stimulates synapse formation, whereas neuroligin 1 that binds to both alpha- and beta-neurexins more effectively promotes synapse expansion. These findings suggest that neuroligin binding to alpha- and beta-neurexins mediates trans-synaptic cell adhesion but has distinct effects on synapse formation, indicating that expression of different neuroligin and neurexin isoforms specifies a trans-synaptic signaling code.
ESTHER : Boucard_2005_Neuron_48_229
PubMedSearch : Boucard_2005_Neuron_48_229
PubMedID: 16242404

Title : Dissection of synapse induction by neuroligins: effect of a neuroligin mutation associated with autism - Chubykin_2005_J.Biol.Chem_280_22365
Author(s) : Chubykin AA , Liu X , Comoletti D , Tsigelny I , Taylor P , Sudhof TC
Ref : Journal of Biological Chemistry , 280 :22365 , 2005
Abstract : To study synapse formation by neuroligins, we co-cultured hippocampal neurons with COS cells expressing wild type and mutant neuroligins. The large size of COS cells makes it possible to test the effect of neuroligins presented over an extended surface area. We found that a uniform lawn of wild type neuroligins displayed on the cell surface triggers the formation of hundreds of uniformly sized, individual synaptic contacts that are labeled with neurexin antibodies. Electron microscopy revealed that these artificial synapses contain a presynaptic active zone with docked vesicles and often feature a postsynaptic density. Neuroligins 1, 2, and 3 were active in this assay. Mutations in two surface loops of neuroligin 1 abolished neuroligin binding to neurexin 1beta, a presumptive presynaptic binding partner for postsynaptic neuroligins, and blocked synapse formation. An analysis of mutant neuroligins with an amino acid substitution that corresponds to a mutation described in patients with an autistic syndrome confirmed previous reports that these mutant neuroligins have a compromised capacity to be transported to the cell surface. Nevertheless, the small percentage of mutant neuroligins that reached the cell surface still induced synapse formation. Viewed together, our data suggest that neuroligins generally promote artificial synapse formation in a manner that is associated with beta-neurexin binding and results in morphologically well differentiated synapses and that a neuroligin mutation found in autism spectrum disorders impairs cell-surface transport but does not completely abolish synapse formation activity.
ESTHER : Chubykin_2005_J.Biol.Chem_280_22365
PubMedSearch : Chubykin_2005_J.Biol.Chem_280_22365
PubMedID: 15797875

Title : Selective capability of SynCAM and neuroligin for functional synapse assembly - Sara_2005_J.Neurosci_25_260
Author(s) : Sara Y , Biederer T , Atasoy D , Chubykin AA , Mozhayeva MG , Sudhof TC , Kavalali ET
Ref : Journal of Neuroscience , 25 :260 , 2005
Abstract : Synaptic cell adhesion is central for synapse formation and function. Recently, the synaptic cell adhesion molecules neuroligin 1 (NL1) and SynCAM were shown to induce presynaptic differentiation in cocultured neurons when expressed in a non-neuronal cell. However, it is uncertain how similar the resulting artificial synapses are to regular synapses. Are these molecules isofunctional, or do all neuronal cell adhesion molecules nonspecifically activate synapse formation? To address these questions, we analyzed the properties of artificial synapses induced by NL1 and SynCAM, compared the actions of these molecules with those of other neuronal cell adhesion molecules, and examined the functional effects of NL1 and SynCAM overexpression in neurons. We found that only NL1 and SynCAM specifically induced presynaptic differentiation in cocultured neurons. The induced nerve terminals were capable of both spontaneous and evoked neurotransmitter release, suggesting that a full secretory apparatus was assembled. By all measures, SynCAM- and NL1-induced artificial synapses were identical. Overexpression in neurons demonstrated that only SynCAM, but not NL1, increased synaptic function in immature developing excitatory neurons after 8 d in vitro. Tests of chimeric molecules revealed that the dominant-positive effect of SynCAM on synaptic function in developing neurons was mediated by its intracellular cytoplasmic tail. Interestingly, morphological analysis of neurons overexpressing SynCAM or NL1 showed the opposite of the predictions from electrophysiological results. In this case, only NL1 increased the synapse number, suggesting a role for NL1 in morphological synapse induction. These results suggest that both NL1 and SynCAM act similarly and specifically in artificial synapse induction but that this process does not reflect a shared physiological function of these molecules.
ESTHER : Sara_2005_J.Neurosci_25_260
PubMedSearch : Sara_2005_J.Neurosci_25_260
PubMedID: 15634790

Title : The synaptic vesicle protein CSP alpha prevents presynaptic degeneration - Fernandez-Chacon_2004_Neuron_42_237
Author(s) : Fernandez-Chacon R , Wolfel M , Nishimune H , Tabares L , Schmitz F , Castellano-Munoz M , Rosenmund C , Montesinos ML , Sanes JR , Schneggenburger R , Sudhof TC
Ref : Neuron , 42 :237 , 2004
Abstract : Cysteine string protein alpha (CSPalpha)--an abundant synaptic vesicle protein that contains a DNA-J domain characteristic of Hsp40 chaperones--is thought to regulate Ca2+ channels and/or synaptic vesicle exocytosis. We now show that, in young mice, deletion of CSPalpha does not impair survival and causes no significant changes in presynaptic Ca2+ currents or synaptic vesicle exocytosis as measured in the Calyx of Held synapse. At 2-4 weeks of age, however, CSPalpha-deficient mice develop a progressive, fatal sensorimotor disorder. The neuromuscular junctions and Calyx synapses of CSPalpha-deficient mice exhibit increasing neurodegenerative changes, synaptic transmission becomes severely impaired, and the mutant mice die at approximately 2 months of age. Our data suggest that CSPalpha is not essential for the normal operation of Ca2+ channels or exocytosis but acts as a presynaptic chaperone that maintains continued synaptic function, raising the possibility that enhanced CSPalpha function could attenuate neurodegenerative diseases.
ESTHER : Fernandez-Chacon_2004_Neuron_42_237
PubMedSearch : Fernandez-Chacon_2004_Neuron_42_237
PubMedID: 15091340

Title : Interaction of recombinant soluble neuroligin-1 with neurexin-1-_. -
Author(s) : Comoletti D , Flynn RE , Jennings LL , Hoffman RC , Marchot P , Bourne Y , Sudhof TC , Taylor P
Ref : Cholinergic Mechanisms, CRC Press :523 , 2004

Title : Structural characterization of recombinant soluble rat neuroligin 1: mapping of secondary structure and glycosylation by mass spectrometry - Hoffman_2004_Biochemistry_43_1496
Author(s) : Hoffman RC , Jennings LL , Tsigelny I , Comoletti D , Flynn RE , Sudhof TC , Taylor P
Ref : Biochemistry , 43 :1496 , 2004
Abstract : Neuroligins (NLs) are a family of transmembrane proteins that function in synapse formation and/or remodeling by interacting with beta-neurexins (beta-NXs) to form heterophilic cell adhesions. The large N-terminal extracellular domain of NLs, required for beta-NX interactions, has sequence homology to the alpha/beta hydrolase fold superfamily of proteins. By peptide mapping and mass spectrometric analysis of a soluble recombinant form of NL1, several structural features of the extracellular domain have been established. Of the nine cysteine residues in NL1, eight are shown to form intramolecular disulfide bonds. Disulfide pairings of Cys 117 to Cys 153 and Cys 342 to Cys 353 are consistent with disulfide linkages that are conserved among the family of alpha/beta hydrolase proteins. The disulfide bond between Cys 172 and Cys 181 occurs within a region of the protein encoded by an alternatively spliced exon. The disulfide pairing of Cys 512 and Cys 546 in NL1 yields a structural motif unique to the NLs, since these residues are highly conserved. The potential N-glycosylation sequons in NL1 at Asn 109, Asn 303, Asn 343, and Asn 547 are shown occupied by carbohydrate. An additional consensus sequence for N-glycosylation at Asn 662 is likely occupied. Analysis of N-linked oligosaccharide content by mass matching paradigms reveals significant microheterogeneous populations of complex glycosyl moieties. In addition, O-linked glycosylation is observed in the predicted stalk region of NL1, prior to the transmembrane spanning domain. From predictions based on sequence homology of NL1 to acetylcholinesterase and the molecular features of NL1 established from mass spectrometric analysis, a novel topology model for NL three-dimensional structure has been constructed.
ESTHER : Hoffman_2004_Biochemistry_43_1496
PubMedSearch : Hoffman_2004_Biochemistry_43_1496
PubMedID: 14769026
Gene_locus related to this paper: ratno-1neur

Title : Characterization of the interaction of a recombinant soluble neuroligin-1 with neurexin-1beta - Comoletti_2003_J.Biol.Chem_278_50497
Author(s) : Comoletti D , Flynn RE , Jennings LL , Chubykin AA , Matsumura T , Hasegawa H , Sudhof TC , Taylor P
Ref : Journal of Biological Chemistry , 278 :50497 , 2003
Abstract : Neuroligins, proteins of the alpha/beta-hydrolase fold family, are found as postsynaptic transmembrane proteins whose extracellular domain associates with presynaptic partners, proteins of the neurexin family. To characterize the molecular basis of neuroligin interaction with neurexin-beta, we expressed five soluble and exportable forms of neuroligin-1 from recombinant DNA sources, by truncating the protein before the transmembrane span near its carboxyl terminus. The extracellular domain of functional neuroligin-1 associates as a dimer when analyzed by sedimentation equilibrium. By surface plasmon resonance, we established that soluble neuroligins-1 bind neurexin-1beta, but the homologous alpha/beta-hydrolase fold protein, acetylcholinesterase, failed to associate with the neurexins. Neuroligin-1 has a unique N-linked glycosylation pattern in the neuroligin family, and glycosylation and its processing modify neuroligin activity. Incomplete processing of the protein and enzymatic removal of the oligosaccharides chain or the terminal sialic acids from neuroligin-1 enhance its activity, whereas deglycosylation of neurexin-1beta did not alter its association capacity. In particular, the N-linked glycosylation at position 303 appears to be a major determinant in modifying the association with neurexin-1beta. We show here that glycosylation processing of neuroligin, in addition to mRNA splicing and gene selection, contributes to the specificity of the neurexin-beta/neuroligin-1 association.
ESTHER : Comoletti_2003_J.Biol.Chem_278_50497
PubMedSearch : Comoletti_2003_J.Biol.Chem_278_50497
PubMedID: 14522992

Title : Munc18-1 promotes large dense-core vesicle docking - Voets_2001_Neuron_31_581
Author(s) : Voets T , Toonen RF , Brian EC , de Wit H , Moser T , Rettig J , Sudhof TC , Neher E , Verhage M
Ref : Neuron , 31 :581 , 2001
Abstract : Secretory vesicles dock at the plasma membrane before Ca(2+) triggers their exocytosis. Exocytosis requires the assembly of SNARE complexes formed by the vesicle protein Synaptobrevin and the membrane proteins Syntaxin-1 and SNAP-25. We analyzed the role of Munc18-1, a cytosolic binding partner of Syntaxin-1, in large dense-core vesicle (LDCV) secretion. Calcium-dependent LDCV exocytosis was reduced 10-fold in mouse chromaffin cells lacking Munc18-1, but the kinetic properties of the remaining release, including single fusion events, were not different from controls. Concomitantly, mutant cells displayed a 10-fold reduction in morphologically docked LDCVs. Moreover, acute overexpression of Munc18-1 in bovine chromaffin cells increased the amount of releasable vesicles and accelerated vesicle supply. We conclude that Munc18-1 functions upstream of SNARE complex formation and promotes LDCV docking.
ESTHER : Voets_2001_Neuron_31_581
PubMedSearch : Voets_2001_Neuron_31_581
PubMedID: 11545717

Title : A stoichiometric complex of neurexins and dystroglycan in brain - Sugita_2001_J.Cell.Biol_154_435
Author(s) : Sugita S , Saito F , Tang J , Satz J , Campbell K , Sudhof TC
Ref : Journal of Cell Biology , 154 :435 , 2001
Abstract : In nonneuronal cells, the cell surface protein dystroglycan links the intracellular cytoskeleton (via dystrophin or utrophin) to the extracellular matrix (via laminin, agrin, or perlecan). Impairment of this linkage is instrumental in the pathogenesis of muscular dystrophies. In brain, dystroglycan and dystrophin are expressed on neurons and astrocytes, and some muscular dystrophies cause cognitive dysfunction; however, no extracellular binding partner for neuronal dystroglycan is known. Regular components of the extracellular matrix, such as laminin, agrin, and perlecan, are not abundant in brain except in the perivascular space that is contacted by astrocytes but not by neurons, suggesting that other ligands for neuronal dystroglycan must exist. We have now identified alpha- and beta-neurexins, polymorphic neuron-specific cell surface proteins, as neuronal dystroglycan receptors. The extracellular sequences of alpha- and beta-neurexins are largely composed of laminin-neurexin-sex hormone-binding globulin (LNS)/laminin G domains, which are also found in laminin, agrin, and perlecan, that are dystroglycan ligands. Dystroglycan binds specifically to a subset of the LNS domains of neurexins in a tight interaction that requires glycosylation of dystroglycan and is regulated by alternative splicing of neurexins. Neurexins are receptors for the excitatory neurotoxin alpha-latrotoxin; this toxin competes with dystroglycan for binding, suggesting overlapping binding sites on neurexins for dystroglycan and alpha-latrotoxin. Our data indicate that dystroglycan is a physiological ligand for neurexins and that neurexins' tightly regulated interaction could mediate cell adhesion between brain cells.
ESTHER : Sugita_2001_J.Cell.Biol_154_435
PubMedSearch : Sugita_2001_J.Cell.Biol_154_435
PubMedID: 11470830

Title : Common EF-hand motifs in cholinesterases and neuroligins suggest a role for Ca2+ binding in cell surface associations - Tsigelny_2000_Protein.Sci_9_180
Author(s) : Tsigelny I , Shindyalov IN , Bourne PE , Sudhof TC , Taylor P
Ref : Protein Science , 9 :180 , 2000
Abstract : Comparisons of protein sequence via cyclic training of Hidden Markov Models (HMMs) in conjunction with alignments of three-dimensional structure, using the Combinatorial Extension (CE) algorithm, reveal two putative EF-hand metal binding domains in acetylcholinesterase. Based on sequence similarity, putative EF-hands are also predicted for the neuroligin family of cell surface proteins. These predictions are supported by experimental evidence. In the acetylcholinesterase crystal structure from Torpedo californica, the first putative EF-hand region binds the Zn2+ found in the heavy metal replacement structure. Further, the interaction of neuroligin 1 with its cognate receptor neurexin depends on Ca2+. Thus, members of the alpha,beta hydrolase fold family of proteins contain potential Ca2+ binding sites, which in some family members may be critical for heterologous cell associations.
ESTHER : Tsigelny_2000_Protein.Sci_9_180
PubMedSearch : Tsigelny_2000_Protein.Sci_9_180
PubMedID: 10739260

Title : Synaptic assembly of the brain in the absence of neurotransmitter secretion - Verhage_2000_Science_287_864
Author(s) : Verhage M , Maia AS , Plomp JJ , Brussaard AB , Heeroma JH , Vermeer H , Toonen RF , Hammer RE , van den Berg TK , Missler M , Geuze HJ , Sudhof TC
Ref : Science , 287 :864 , 2000
Abstract : Brain function requires precisely orchestrated connectivity between neurons. Establishment of these connections is believed to require signals secreted from outgrowing axons, followed by synapse formation between selected neurons. Deletion of a single protein, Munc18-1, in mice leads to a complete loss of neurotransmitter secretion from synaptic vesicles throughout development. However, this does not prevent normal brain assembly, including formation of layered structures, fiber pathways, and morphologically defined synapses. After assembly is completed, neurons undergo apoptosis, leading to widespread neurodegeneration. Thus, synaptic connectivity does not depend on neurotransmitter secretion, but its maintenance does. Neurotransmitter secretion probably functions to validate already established synaptic connections.
ESTHER : Verhage_2000_Science_287_864
PubMedSearch : Verhage_2000_Science_287_864
PubMedID: 10657302

Title : Neuroligin 1 is a postsynaptic cell-adhesion molecule of excitatory synapses - Song_1999_Proc.Natl.Acad.Sci.U.S.A_96_1100
Author(s) : Song JY , Ichtchenko K , Sudhof TC , Brose N
Ref : Proc Natl Acad Sci U S A , 96 :1100 , 1999
Abstract : At the synapse, presynaptic membranes specialized for vesicular traffic are linked to postsynaptic membranes specialized for signal transduction. The mechanisms that connect pre- and postsynaptic membranes into synaptic junctions are unknown. Neuroligins and beta-neurexins are neuronal cell-surface proteins that bind to each other and form asymmetric intercellular junctions. To test whether the neuroligin/beta-neurexin junction is related to synapses, we generated and characterized monoclonal antibodies to neuroligin 1. With these antibodies, we show that neuroligin 1 is synaptic. The neuronal localization, subcellular distribution, and developmental expression of neuroligin 1 are similar to those of the postsynaptic marker proteins PSD-95 and NMDA-R1 receptor. Quantitative immunogold electron microscopy demonstrated that neuroligin 1 is clustered in synaptic clefts and postsynaptic densities. Double immunofluorescence labeling revealed that neuroligin 1 colocalizes with glutamatergic but not gamma-aminobutyric acid (GABA)ergic synapses. Thus neuroligin 1 is a synaptic cell-adhesion molecule that is enriched in postsynaptic densities where it may recruit receptors, channels, and signal-transduction molecules to synaptic sites of cell adhesion. In addition, the neuroligin/beta-neurexin junction may be involved in the specification of excitatory synapses.
ESTHER : Song_1999_Proc.Natl.Acad.Sci.U.S.A_96_1100
PubMedSearch : Song_1999_Proc.Natl.Acad.Sci.U.S.A_96_1100
PubMedID: 9927700
Gene_locus related to this paper: ratno-1neur

Title : Metal Binding Motifs in Cholinesterases and Neuroligins -
Author(s) : Tsigelny I , Matsumura T , Sudhof TC , Taylor P
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :407 , 1998

Title : The making of neurexins - Missler_1998_J.Neurochem_71_1339
Author(s) : Missler M , Fernandez-Chacon R , Sudhof TC
Ref : Journal of Neurochemistry , 71 :1339 , 1998
Abstract : Neurexins are neuronal cell-surface proteins with up to thousands of isoforms. These isoforms are generated by alternative splicing of transcripts from six promoters in three genes. The structure of neurexins resembles cell-surface receptors with a modular architecture suggestive of a sequential assembly during evolution. Neurexins probably perform multiple functions in the brain. They participate in intercellular junctions in which beta-neurexins tightly bind to a second class of neuronal cell-surface receptors called neuroligins. Intracellularly, the neurexin/neuroligin junction is bound by CASK on the neurexin side and PSD95 on the neuroligin side. CASK and PSD95 are homologous membrane-associated guanylate kinases that bind to the neurexin/neuroligin junction via PDZ domains, creating an asymmetric junction (neurexin/neuroligin) with similar intracellular binding partners. In addition to a function as cell-adhesion molecules, neurexins may also serve as a signalling receptor, because a class of ligands for alpha-neurexins called neurexophilins is similar to peptide hormones. Finally, at least one neurexin isoform, neurexin Ialpha, represents a high-affinity receptor for alpha-latrotoxin, which is a potent excitatory neurotoxin. Thus, neurexins constitute a large family of neuronal receptors that may be involved in multiple interactive functions between neurons.
ESTHER : Missler_1998_J.Neurochem_71_1339
PubMedSearch : Missler_1998_J.Neurochem_71_1339
PubMedID: 9751164

Title : A novel multiple PDZ domain-containing molecule interacting with N-methyl-D-aspartate receptors and neuronal cell adhesion proteins - Hirao_1998_J.Biol.Chem_273_21105
Author(s) : Hirao K , Hata Y , Ide N , Takeuchi M , Irie M , Yao I , Deguchi M , Toyoda A , Sudhof TC , Takai Y
Ref : Journal of Biological Chemistry , 273 :21105 , 1998
Abstract : At synaptic junctions, pre- and postsynaptic membranes are connected by cell adhesion and have distinct structures for specialized functions. The presynaptic membranes have a machinery for fast neurotransmitter release, and the postsynaptic membranes have clusters of neurotransmitter receptors. The molecular mechanism of the assembly of synaptic junctions is not yet clear. Pioneering studies identified postsynaptic density (PSD)-95/SAP90 as a prototypic synaptic scaffolding protein to maintain the structure of synaptic junctions. PSD-95/SAP90 belongs to a family of membrane-associated guanylate kinases and binds N-methyl-D-aspartate receptors, potassium channels, and neuroligins through the PDZ domains and GKAP/SAPAP/DAP through the guanylate kinase (GK) domain. We performed here a yeast two-hybrid screening for SAPAP-interacting molecules and identified a novel protein that has an inverse structure of membrane-associated guanylate kinases with an NH2-terminal GK-like domain followed by two WW and five PDZ domains. It binds SAPAP through the GK-like domain and NMDA receptors and neuroligins through the PDZ domains. We named this protein S-SCAM (synaptic scaffolding molecule) because S-SCAM may assemble receptors and cell adhesion proteins at synaptic junctions.
ESTHER : Hirao_1998_J.Biol.Chem_273_21105
PubMedSearch : Hirao_1998_J.Biol.Chem_273_21105
PubMedID: 9694864
Gene_locus related to this paper: ratno-1neur

Title : Munc13-1 is a presynaptic phorbol ester receptor that enhances neurotransmitter release - Betz_1998_Neuron_21_123
Author(s) : Betz A , Ashery U , Rickmann M , Augustin I , Neher E , Sudhof TC , Rettig J , Brose N
Ref : Neuron , 21 :123 , 1998
Abstract : Munc13-1, a mammalian homolog of C. elegans unc-13p, is thought to be involved in the regulation of synaptic transmission. We now demonstrate that Munc13-1 is a presynaptic high-affinity phorbol ester and diacylglycerol receptor with ligand affinities similar to those of protein kinase C. Munc13-1 associates with the plasma membrane in response to phorbol ester binding and acts as a phorbol ester-dependent enhancer of transmitter release when overexpressed presynaptically in the Xenopus neuromuscular junction. These observations establish Munc13-1 as a novel presynaptic target of the diacylglycerol second messenger pathway that acts in parallel with protein kinase C to regulate neurotransmitter secretion.
ESTHER : Betz_1998_Neuron_21_123
PubMedSearch : Betz_1998_Neuron_21_123
PubMedID: 9697857

Title : Binding of neuroligins to PSD-95 - Irie_1997_Science_277_1511
Author(s) : Irie M , Hata Y , Takeuchi M , Ichtchenko K , Toyoda A , Hirao K , Takai Y , Rosahl TW , Sudhof TC
Ref : Science , 277 :1511 , 1997
Abstract : PSD-95 is a component of postsynaptic densities in central synapses. It contains three PDZ domains that localize N-methyl-D-aspartate receptor subunit 2 (NMDA2 receptor) and K+ channels to synapses. In mouse forebrain, PSD-95 bound to the cytoplasmic COOH-termini of neuroligins, which are neuronal cell adhesion molecules that interact with beta-neurexins and form intercellular junctions. Neuroligins bind to the third PDZ domain of PSD-95, whereas NMDA2 receptors and K+ channels interact with the first and second PDZ domains. Thus different PDZ domains of PSD-95 are specialized for distinct functions. PSD-95 may recruit ion channels and neurotransmitter receptors to intercellular junctions formed between neurons by neuroligins and beta-neurexins.
ESTHER : Irie_1997_Science_277_1511
PubMedSearch : Irie_1997_Science_277_1511
PubMedID: 9278515
Gene_locus related to this paper: human-NLGN1 , human-NLGN2 , human-NLGN3 , human-NLGN4X

Title : Binding properties of neuroligin 1 and neurexin 1beta reveal function as heterophilic cell adhesion molecules - Nguyen_1997_J.Biol.Chem_272_26032
Author(s) : Nguyen T , Sudhof TC
Ref : Journal of Biological Chemistry , 272 :26032 , 1997
Abstract : beta-Neurexins and neuroligins are plasma membrane proteins that are displayed on the neuronal cell surface. We have now investigated the interaction of neurexin 1beta with neuroligin 1 to evaluate their potential to function as heterophilic cell adhesion molecules. Using detergent-solubilized neuroligins and secreted neurexin 1beta-IgG fusion protein, we observed binding of these proteins to each other only in the presence of Ca2+ and in no other divalent cation tested. Only neurexin 1beta lacking an insert in splice site 4 bound neuroligins, whereas neurexin 1beta containing an insert was inactive. Half-maximal binding required 1-3 microM free Ca2+, which probably acts by binding to neuroligin 1 but not to neurexin 1beta. To determine if neurexin 1beta and neuroligin 1 can also interact with each other when present in a native membrane environment on the cell surface, we generated transfected cell lines expressing neuroligin 1 and neurexin 1beta. Upon mixing different cell populations, we found that cells aggregate only if cells expressing neurexin 1beta are mixed with cells expressing neuroligin 1. Aggregation was dependent on Ca2+ and was inhibited by the addition of soluble neurexin 1beta lacking an insert in splice site 4 but not by the addition of neurexin 1beta containing an insert in splice site 4. We conclude that neurexin 1beta and neuroligin 1 (and, by extension, other beta-neurexins and neuroligins) function as heterophilic cell adhesion molecules in a Ca2+-dependent reaction that is regulated by alternative splicing of beta-neurexins.
ESTHER : Nguyen_1997_J.Biol.Chem_272_26032
PubMedSearch : Nguyen_1997_J.Biol.Chem_272_26032
PubMedID: 9325340
Gene_locus related to this paper: ratno-1neur

Title : Structures, alternative splicing, and neurexin binding of multiple neuroligins - Ichtchenko_1996_J.Biol.Chem_271_2676
Author(s) : Ichtchenko K , Nguyen T , Sudhof TC
Ref : Journal of Biological Chemistry , 271 :2676 , 1996
Abstract : Neuroligin 1 is a neuronal cell surface protein that binds to a subset of neurexins, polymorphic cell surface proteins that are also localized on neurons (Ichtchenko, K., Hata, Y., Nguyen, T., Ullrich, B., Missler, M., Moomaw, C., and Sudhof, T. C. (1995) Cell 81, 435-443). We now describe two novel neuroligins called neuroligins 2 and 3 that are similar in structure and sequence to neuroligin 1. All neuroligins contain an N-terminal hydrophobic sequence with the characteristics of a cleaved signal peptide followed by a large esterase homology domain, a highly conserved single transmembrane region, and a short cytoplasmic domain. The three neuroligins are alternatively spliced at the same position and are expressed at high levels only in brain. Binding studies demonstrate that all three neuroligins bind to beta-neurexins both as native brain proteins and as recombinant proteins. Tight binding of the three neuroligins to beta-neurexins is observed only for beta-neurexins lacking an insert in splice site 4. Thus, neuroligins constitute a multigene family of brain-specific proteins with distinct isoforms that may have overlapping functions in mediating recognition processes between neurons.
ESTHER : Ichtchenko_1996_J.Biol.Chem_271_2676
PubMedSearch : Ichtchenko_1996_J.Biol.Chem_271_2676
PubMedID: 8576240
Gene_locus related to this paper: ratno-1neur , ratno-2neur , ratno-3neur

Title : Neuroligin 1: a splice site-specific ligand for beta-neurexins - Ichtchenko_1995_Cell_81_435
Author(s) : Ichtchenko K , Hata Y , Nguyen T , Ullrich B , Missler M , Moomaw C , Sudhof TC
Ref : Cell , 81 :435 , 1995
Abstract : Neurexins are neuronal cell surface proteins with hundreds of isoforms generated by alternative splicing. Here we describe neuroligin 1, a neuronal cell surface protein that is enriched in synaptic plasma membranes and acts as a splice site-specific ligand for beta-neurexins. Neuroligin 1 binds to beta-neurexins only if they lack an insert in the alternatively spliced sequence of the G domain, but not if they contain an insert. The extracellular sequence of neuroligin 1 is composed of a catalytically inactive esterase domain homologous to acetylcholinesterase. In situ hybridization reveals that alternative splicing of neurexins at the site recognized by neuroligin 1 is highly regulated. These findings support a model whereby alternative splicing of neurexins creates a family of cell surface receptors that confers interactive specificity onto their resident neurons.
ESTHER : Ichtchenko_1995_Cell_81_435
PubMedSearch : Ichtchenko_1995_Cell_81_435
PubMedID: 7736595
Gene_locus related to this paper: ratno-1neur , ratno-2neur

Title : Molecular approaches to synaptic vesicle exocytosis -
Author(s) : Sudhof TC , Petrenko AG , Whittaker VP , Jahn R
Ref : Prog Brain Res , 98 :235 , 1993
PubMedID: 8248512

Title : rab3 is a small GTP-binding protein exclusively localized to synaptic vesicles - Fischer_1990_Proc.Natl.Acad.Sci.U.S.A_87_1988
Author(s) : Fischer von Mollard G , Mignery GA , Baumert M , Perin MS , Hanson TJ , Burger PM , Jahn R , Sudhof TC
Ref : Proc Natl Acad Sci U S A , 87 :1988 , 1990
Abstract : rab3, a low molecular weight GTP-binding protein, is primarily expressed in brain, where it is present in soluble and membrane-bound forms. Membrane-bound rab3 in brain is exclusively localized on synaptic vesicles, the secretory organelles of the synapse that store and release neurotransmitters. rab3 is also expressed in endocrine tissues such as the adrenal medulla, where it is found together with other synaptic vesicle proteins on microvesicles distinct from chromaffin granules. The tight binding of rab3 to membranes correlates with hydrophobic modifications that are different in the membrane-bound and soluble forms of rab3. The results demonstrate the exclusive targeting of a small GTP-binding protein to secretory vesicles of a subset of the regulated pathway of secretion.
ESTHER : Fischer_1990_Proc.Natl.Acad.Sci.U.S.A_87_1988
PubMedSearch : Fischer_1990_Proc.Natl.Acad.Sci.U.S.A_87_1988
PubMedID: 2155429