Nithianantharajah J

References (5)

Title : Postsynaptic Neuroligin-1 Mediates Presynaptic Endocytosis During Neuronal Activity - Luo_2021_Front.Mol.Neurosci_14_744845
Author(s) : Luo JK , Melland H , Nithianantharajah J , Gordon SL
Ref : Front Mol Neurosci , 14 :744845 , 2021
Abstract : Fast, high-fidelity neurotransmission and synaptic efficacy requires tightly regulated coordination of pre- and postsynaptic compartments and alignment of presynaptic release sites with postsynaptic receptor nanodomains. Neuroligin-1 (Nlgn1) is a postsynaptic cell-adhesion protein exclusively localised to excitatory synapses that is crucial for coordinating the transsynaptic alignment of presynaptic release sites with postsynaptic AMPA receptors as well as postsynaptic transmission and plasticity. However, little is understood about whether the postsynaptic machinery can mediate the molecular architecture and activity of the presynaptic nerve terminal, and thus it remains unclear whether there are presynaptic contributions to Nlgn1-dependent control of signalling and plasticity. Here, we employed a presynaptic reporter of neurotransmitter release and synaptic vesicle dynamics, synaptophysin-pHluorin (sypHy), to directly assess the presynaptic impact of loss of Nlgn1. We show that lack of Nlgn1 had no effect on the size of the readily releasable or entire recycling pool of synaptic vesicles, nor did it impact exocytosis. However, we observed significant changes in the retrieval of synaptic vesicles by compensatory endocytosis, specifically during activity. Our data extends growing evidence that synaptic adhesion molecules critical for forming transsynaptic scaffolds are also important for regulating activity-induced endocytosis at the presynapse.
ESTHER : Luo_2021_Front.Mol.Neurosci_14_744845
PubMedSearch : Luo_2021_Front.Mol.Neurosci_14_744845
PubMedID: 34690694

Title : Altered Caecal Neuroimmune Interactions in the Neuroligin-3(R451C) Mouse Model of Autism - Sharna_2020_Front.Cell.Neurosci_14_85
Author(s) : Sharna SS , Balasuriya GK , Hosie S , Nithianantharajah J , Franks AE , Hill-Yardin EL
Ref : Front Cell Neurosci , 14 :85 , 2020
Abstract : The intrinsic nervous system of the gut interacts with the gut-associated lymphoid tissue (GALT) via bidirectional neuroimmune interactions. The caecum is an understudied region of the gastrointestinal (GI) tract that houses a large supply of microbes and is involved in generating immune responses. The caecal patch is a lymphoid aggregate located within the caecum that regulates microbial content and immune responses. People with Autism Spectrum Disorder (ASD; autism) experience serious GI dysfunction, including inflammatory disorders, more frequently than the general population. Autism is a highly prevalent neurodevelopmental disorder defined by the presence of repetitive behavior or restricted interests, language impairment, and social deficits. Mutations in genes encoding synaptic adhesion proteins such as the R451C missense mutation in neuroligin-3 (NL3) are associated with autism and impair synaptic transmission. We previously reported that NL3(R451C) mice, a well-established model of autism, have altered enteric neurons and GI dysfunction; however, whether the autism-associated R451C mutation alters the caecal enteric nervous system and immune function is unknown. We assessed for gross anatomical changes in the caecum and quantified the proportions of caecal submucosal and myenteric neurons in wild-type and NL3(R451C) mice using immunofluorescence. In the caecal patch, we assessed total cellular density as well as the density and morphology of Iba-1 labeled macrophages to identify whether the R451C mutation affects neuro-immune interactions. NL3(R451C) mice have significantly reduced caecal weight compared to wild-type mice, irrespective of background strain. Caecal weight is also reduced in mice lacking Neuroligin-3. NL3(R451C) caecal ganglia contain more neurons overall and increased numbers of Nitric Oxide (NO) producing neurons (labeled by Nitric Oxide Synthase; NOS) per ganglion in both the submucosal and myenteric plexus. Overall caecal patch cell density was unchanged however NL3(R451C) mice have an increased density of Iba-1 labeled enteric macrophages. Macrophages in NL3(R451C) were smaller and more spherical in morphology. Here, we identify changes in both the nervous system and immune system caused by an autism-associated mutation in Nlgn3 encoding the postsynaptic cell adhesion protein, Neuroligin-3. These findings provide further insights into the potential modulation of neural and immune pathways.
ESTHER : Sharna_2020_Front.Cell.Neurosci_14_85
PubMedSearch : Sharna_2020_Front.Cell.Neurosci_14_85
PubMedID: 32327975
Gene_locus related to this paper: human-NLGN3

Title : Colonic dilation and altered ex vivo gastrointestinal motility in the neuroligin-3 knockout mouse - Leembruggen_2020_Autism.Res_13_691
Author(s) : Leembruggen AJL , Balasuriya GK , Zhang J , Schokman S , Swiderski K , Bornstein JC , Nithianantharajah J , Hill-Yardin EL
Ref : Autism Res , 13 :691 , 2020
Abstract : Gastrointestinal (GI) dysfunction is commonly reported by people diagnosed with autism spectrum disorder (ASD; autism) but the cause is unknown. Mutations in genes encoding synaptic proteins including Neuroligin-3 are associated with autism. Mice lacking Neuroligin-3 (Nlgn3(-/-) ) have altered brain function, but whether the enteric nervous system (ENS) is altered remains unknown. We assessed for changes in GI structure and function in Nlgn3(-/-) mice. We found no significant morphological differences in villus height or crypt depth in the jejunum or colon between wildtype (WT) and Nlgn3(-/-) mice. To determine whether deletion of Nlgn3 affects enteric neurons, we stained for neural markers in the myenteric plexus. Nlgn3(-/-) mice had similar numbers of neurons expressing the pan-neuronal marker Hu in the jejunum, proximal mid, and distal colon regions. We also found no differences in the number of neuronal nitric oxide synthase (nNOS+) or calretinin (CalR+) motor neurons and interneurons between WT and Nlgn3(-/-) mice. We used ex vivo video imaging analysis to assess colonic motility under baseline conditions and observed faster colonic migrating motor complexes (CMMCs) and an increased colonic diameter in Nlgn3(-/-) mice, although CMMC frequency was unchanged. At baseline, CMMCs were faster in Nlgn3(-/-) mice compared to WT. Although the numbers of neuronal subsets are conserved in Nlgn3(-/-) mice, these findings suggest that Neuroligin-3 modulates inhibitory neural pathways in the ENS and may contribute to mechanisms underlying GI disorders in autism. Autism Res 2020, 13: 691-701. 2019 The Authors. Autism Research published by International Society for Autism Research published byWiley Periodicals, Inc. LAY SUMMARY: People with autism commonly experience gut problems. Many gene mutations associated with autism affect neuronal activity. We studied mice in which the autism-associated Neuroligin-3 gene is deleted to determine whether this impacts gut neuronal numbers or motility. We found that although mutant mice had similar gut structure and numbers of neurons in all gut regions examined, they had distended colons and faster colonic muscle contractions. Further work is needed to understand how Neuroligin-3 affects neuron connectivity in the gastrointestinal tract.
ESTHER : Leembruggen_2020_Autism.Res_13_691
PubMedSearch : Leembruggen_2020_Autism.Res_13_691
PubMedID: 31002480

Title : A molecular insight into the dissociable regulation of associative learning and motivation by the synaptic protein neuroligin-1 - Luo_2020_BMC.Biol_18_118
Author(s) : Luo J , Tan JM , Nithianantharajah J
Ref : BMC Biol , 18 :118 , 2020
Abstract : BACKGROUND: In a changing environment, a challenge for the brain is to flexibly guide adaptive behavior towards survival. Complex behavior and the underlying neural computations emerge from the structural components of the brain across many levels: circuits, cells, and ultimately the signaling complex of proteins at synapses. In line with this logic, dynamic modification of synaptic strength or synaptic plasticity is widely considered the cellular level implementation for adaptive behavior such as learning and memory. Predominantly expressed at excitatory synapses, the postsynaptic cell-adhesion molecule neuroligin-1 (Nlgn1) forms trans-synaptic complexes with presynaptic neurexins. Extensive evidence supports that Nlgn1 is essential for NMDA receptor transmission and long-term potentiation (LTP), both of which are putative synaptic mechanisms underlying learning and memory. Here, employing a comprehensive battery of touchscreen-based cognitive assays, we asked whether impaired NMDA receptor transmission and LTP in mice lacking Nlgn1 does in fact disrupt decision-making. To this end, we addressed two key decision problems: (i) the ability to learn and exploit the associative structure of the environment and (ii) balancing the trade-off between potential rewards and costs, or positive and negative utilities of available actions. RESULTS: We found that the capacity to acquire complex associative structures and adjust learned associations was intact. However, loss of Nlgn1 alters motivation leading to a reduced willingness to overcome effort cost for reward and an increased willingness to exert effort to escape an aversive situation. We suggest Nlgn1 may be important for balancing the weighting on positive and negative utilities in reward-cost trade-off. CONCLUSIONS: Our findings update canonical views of this key synaptic molecule in behavior and suggest Nlgn1 may be essential for regulating distinct cognitive processes underlying action selection. Our data demonstrate that learning and motivational computations can be dissociated within the same animal model, from a detailed behavioral dissection. Further, these results highlight the complexities in mapping synaptic mechanisms to their behavioral consequences, and the future challenge to elucidate how complex behavior emerges through different levels of neural hardware.
ESTHER : Luo_2020_BMC.Biol_18_118
PubMedSearch : Luo_2020_BMC.Biol_18_118
PubMedID: 32921313

Title : Mutations in neuroligin-3 in male mice impact behavioral flexibility but not relational memory in a touchscreen test of visual transitive inference - Norris_2019_Mol.Autism_10_42
Author(s) : Norris RHC , Churilov L , Hannan AJ , Nithianantharajah J
Ref : Mol Autism , 10 :42 , 2019
Abstract : Cognitive dysfunction including disrupted behavioral flexibility is central to neurodevelopmental disorders such as Autism Spectrum Disorder (ASD). A cognitive measure that assesses relational memory, and the ability to flexibly assimilate and transfer learned information is transitive inference. Transitive inference is highly conserved across vertebrates and disrupted in cognitive disorders. Here, we examined how mutations in the synaptic cell-adhesion molecule neuroligin-3 (Nlgn3) that have been documented in ASD impact relational memory and behavioral flexibility. We first refined a rodent touchscreen assay to measure visual transitive inference, then assessed two mouse models of Nlgn3 dysfunction (Nlgn3 (-/y) and Nlgn3 (R451C)). Deep analysis of touchscreen behavioral data at a trial level established we could measure trajectories in flexible responding and changes in processing speed as cognitive load increased. We show that gene mutations in Nlgn3 do not disrupt relational memory, but significantly impact flexible responding. Our study presents the first analysis of reaction times in a rodent transitive inference test, highlighting response latencies from the touchscreen system are useful indicators of processing demands or decision-making processes. These findings expand our understanding of how dysfunction of key components of synaptic signaling complexes impact distinct cognitive processes disrupted in neurodevelopmental disorders, and advance our approaches for dissecting rodent behavioral assays to provide greater insights into clinically relevant cognitive symptoms.
ESTHER : Norris_2019_Mol.Autism_10_42
PubMedSearch : Norris_2019_Mol.Autism_10_42
PubMedID: 31827744
Gene_locus related to this paper: mouse-3neur , human-NLGN3