Mechanisms of Central Neuron Synaptogenesis

中枢神经元突触发生的机制

基本信息

批准号：
7429715
负责人：
ANN M CRAIG
金额：
$ 20.74万
依托单位：
UNIVERSITY OF BRITISH COLUMBIA
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-06-01 至 2010-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7429715
关键词：
Address Agrin Alternative Splicing Autistic Disorder Axon Binding Biological Assay Brain Cell Adhesion Cells Chromosome Pairing Coculture Techniques DLG4 gene Data Dendrites Development Dominant-Negative Mutation Extracellular Domain Fibroblasts GABA Receptor Genes Genus Mentha Glutamate Receptor Glutamates Goals Gonadal Steroid Hormones Hippocampus (Brain)Individual Inhibitory Synapse Knock-out Knowledge Laminin Link Localized Mediating Membrane Proteins N-Methylaspartate Natural regeneration Neurons PDZ protein Point Mutation Protein Isoforms Protein Overexpression Proteins RNA Interference RNA Splicing Research Role Scaffolding Protein Site Structure Surface Synapses Synaptic Vesicles System Tertiary Protein Structure Testing Therapeutic Trauma gamma-Aminobutyric Acid gephyrin hormone binding protein immunocytochemistry interest knock-down nervous system disorder neurexophilin neuroligin 1 novel postsynaptic presynaptic presynaptic density protein 95 programs promoter receptor receptor binding research study synaptogenesis synaptotagmin

项目摘要

DESCRIPTION (provided by applicant): The long-term goal of this research is to understand how central neuron synapses form. Our current focus is to test the function of neurexins in synapse formation between hippocampal neurons. Beta-neurexins bind to neuroligins-1, a component of glutamate postsynaptic sites. Since neurexins bind synaptotagmin and presynaptic PDZ proteins including CASK and Mints, and neuroligins bind postsynaptic PDZ proteins including PSD-95, it has been suggested that the trans-synaptic neurexin-neuroligin interaction is involved in initiation of glutamatergic synapses. Furthermore, neuroligins expressed on the surface of fibroblasts can induce clustering of synaptic vesicles in contacting axons, both glutamate and GABA axons. In preliminary experiments, we found that neurexin expressed on the surface of fibroblasts induces clustering of the excitatory postsynaptic scaffolding protein PSD-95 and NMDA glutamate receptors, and of the inhibitory postsynaptic scaffolding protein gephyrin and GABA receptors, in contacting dendrites. Other proteins distantly related to neurexins including agrin cannot cluster either glutamate or GABA postsynaptic components. A putative role for neurexins at GABA synapses is supported by the expression and presynaptic localization of neurexins in GABA as well as glutamate axons. Thus the present state of knowledge suggests a central role for neurexins in both glutamate and GABA synapse formation, but our knowledge is incomplete. We propose to test the hypothesis that different isoforms of neurexins, and perhaps neuroligins, promote differentiation of glutamate and GABA synapses. We will define the residues of neurexin-lb necessary for inducing clustering of GABA and glutamate postsynaptic components, and test the possibility that different neuroligin isoforms mediate these effects. We will test the other neurexin isoforms la, 2a/b, and 3a/b for similar inducing and binding activity. We will determine the subcellular distributions of different neuroligin isoforms, and test their ability to induce presynaptic differentiation in GABA and glutamate axons. Finally, we will use two approaches to knock out the function of neurexins in hippocampal cultures and determine whether neurexins are essential for any aspect of synaptogenesis. These experiments address fundamental mechanisms of brain development with implications for therapeutic approaches to regeneration following neurological disorders or trauma.

描述（由申请人提供）：这项研究的长期目标是了解中枢神经元突触是如何形成的。我们目前的重点是测试神经毒素在海马神经元之间突触形成中的功能。 β-neurexins 与 Neuroligins-1（谷氨酸突触后位点的组成部分）结合。由于神经毒素结合突触结合蛋白和突触前 PDZ 蛋白（包括 CASK 和 Mints），而神经连接蛋白结合突触后 PDZ 蛋白（包括 PSD-95），因此有人认为跨突触神经毒素-神经连接蛋白相互作用参与谷氨酸能突触的启动。此外，成纤维细胞表面表达的神经胶质素可以诱导接触轴突（谷氨酸轴突和 GABA 轴突）中的突触小泡聚集。在初步实验中，我们发现成纤维细胞表面表达的神经毒素在接触树突时诱导兴奋性突触后支架蛋白 PSD-95 和 NMDA 谷氨酸受体以及抑制性突触后支架蛋白 gephyrin 和 GABA 受体聚集。其他与神经毒素关系较远的蛋白质（包括集聚蛋白）不能聚集谷氨酸或 GABA 突触后成分。神经毒素在 GABA 突触中的假定作用得到了神经毒素在 GABA 以及谷氨酸轴突中的表达和突触前定位的支持。因此，目前的知识表明神经毒素在谷氨酸和 GABA 突触形成中发挥着核心作用，但我们的知识并不完整。我们建议检验以下假设：不同亚型的神经毒素（可能还有神经肽）促进谷氨酸和 GABA 突触的分化。我们将定义诱导 GABA 和谷氨酸突触后成分聚集所需的 neurexin-1b 残基，并测试不同的 Neuroligin 亚型介导这些作用的可能性。我们将测试其他神经素亚型 la、2a/b 和 3a/b 的类似诱导和结合活性。我们将确定不同 Neuroligin 亚型的亚细胞分布，并测试它们诱导 GABA 和谷氨酸轴突突触前分化的能力。最后，我们将使用两种方法来敲除海马培养物中神经毒素的功能，并确定神经毒素是否对突触发生的任何方面都至关重要。这些实验探讨了大脑发育的基本机制，对神经系统疾病或创伤后的再生治疗方法具有影响。