Exploring the mechanisms of Semaphorin/Plexin-mediated synapse formation in the intact hippocampus

探索完整海马中 Semaphorin/Plexin 介导的突触形成机制

• 批准号: 10373966
• 负责人: Susannah Adel
• 金额: $ 3.54万
• 依托单位: BRANDEIS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-03-16 至 2023-03-15
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10373966
• 关键词: Adult; Affinity; Alzheimer' s Disease; Attention; Biological Assay; Brain; CD100 antigen; Cell Communication; Cell physiology; Cells; Chimera organism; Clinical; Cognition Disorders; Complex; Cytoskeletal Modeling; Data; Development; Down Syndrome; ERBB2 gene; Ephrins; Epilepsy; Excitatory Synapse; Exhibits; Extracellular Domain; Family; Genes; Glutamates; Heterodimerization; Hippocampus (Brain); Homo; Imaging technology; Inhibitory Synapse; Ion Channel Gating; Knock-out; Knockout Mice; Ligands; Link; Mediating; Mental disorders; Modeling; Molecular; Molecular Conformation; Mus; Nervous system structure; Neuraxis; Neurodegenerative Disorders; Neuroglia; Neurotransmitters; Pathway interactions; Pharmacology; Play; Process; Property; Protein Family; Proteins; RNA Interference; Receptor Protein-Tyrosine Kinases; Recombinants; Research; Rodent; Role; SEMA3F gene; Scaffolding Protein; Seizures; Semaphorins; Signal Pathway; Signal Transduction; Slice; Specific qualifier value; Synapses; Synaptic Vesicles; Testing; Time; To specify; Transgenic Mice; Transmembrane Domain; Work; autism spectrum disorder; axon guidance; cell type; density; developmental neurobiology; excitatory neuron; experimental study; forward genetics; gamma-Aminobutyric Acid; gene discovery; genetic manipulation; genome-wide; high resolution imaging; in vivo; inhibitor; inhibitory neuron; knock-down; mutant; nervous system development; novel; overexpression; plexin; postsynaptic; postsynaptic neurons; presynaptic; receptor; resilience; response; reverse genetics; synaptic function; synaptogenesis; tool

Project Summary: In the mammalian central nervous system, two main types of synapses – glutamatergic and GABAergic – play opposing roles in exciting or inhibiting the postsynaptic cell. While it is critical that upon cell-cell contact, new synapses form the correct postsynaptic specialization (excitatory or inhibitory), the molecular pathways specifying this identity remain a fundamental mystery in developmental neurobiology. This process is presumably regulated by trans-synaptic ligand/receptor partners that belong to protein families (e.g. Neuroligins/Neurexins, Ephrins/Ephs, Semaphorins/Plexins) which have been demonstrated to regulate both excitatory and inhibitory synapse formation. Semaphorins (Semas) and Plexins are families of widely expressed and functionally versatile transmembrane or secreted ligands and their transmembrane receptors that first gained attention for their roles in axon guidance during nervous system development. Class 4 Semas and Plexin-B receptors are expressed in mammalian hippocampus (in excitatory and inhibitory neurons and in glia) and promote synapse formation both during development and in adulthood. Our previous studies revealed Sema4D to be one of few molecules having synaptogenic function restricted to inhibitory synapses; the extracellular domain of Sema4D induces inhibitory synapse formation on a rapid timescale (~30 mins) through the Plexin-B1 receptor. Additionally, Sema4A promotes formation of both inhibitory and excitatory synapses in hippocampus via the Plexin-B1 or Plexin-B2 receptors, respectively. The ability to rapidly drive synapse formation by application of Sema4A or Sema4D, as well as the observations that these Semas regulate inhibitory and excitatory synapse formation in unique ways requiring different Plexin-B receptors, are central to our proposed strategy to identify the distinct signaling conformations that instruct synapse identity (excitatory or inhibitory) downstream of Plexin-B receptor engagement. Further, we previously showed that Sema4D protein application increases resilience to seizure in adult mice in vivo, a finding that supports the potential clinical impact of this work. The proposed research uses a combination of transgenic mice, organotypic hippocampal slice culture, gene knockdown, and expression of mutant forms of Plexin-B receptors to examine the divergent roles of 1) unique Plexin-B signaling domains, 2) a novel mechanism gating Plexin-B1 signaling in cis, and 3) contributions from Plexin-B coreceptors, in excitatory and inhibitory synapse formation promoted by class 4 semaphorins.

项目总结： 在哺乳动物中枢神经系统中，两种主要类型的突触-谷氨酸能和GABA能-发挥作用 在刺激或抑制突触后细胞中扮演相反的角色。虽然在细胞-细胞接触时，新的 突触形成正确的突触后特化(兴奋性或抑制性)，即分子通路 确定这一身份仍然是发育神经生物学中的一个基本谜团。这个过程是 推测是由属于蛋白质家族的跨突触配体/受体伙伴调节的。 神经连接蛋白/Neurexins、Eparins/Ephs、信号素/丛蛋白)，它们已被证明调节两者 兴奋性和抑制性突触形成。 信号素(Sema)和丛状蛋白(Plexin)是广泛表达和功能多样的跨膜蛋白家族 分泌型配体及其跨膜受体首次因其在轴突引导中的作用而受到关注 在神经系统发育过程中。4类Semas和Plexin-B受体在哺乳动物中的表达 海马体(在兴奋性和抑制性神经元以及神经胶质细胞中)和促进突触的形成 发展阶段和成年阶段。 我们之前的研究表明Sema4D是少数几个具有突触发生功能的分子之一 抑制性突触；Sema4D的胞外区诱导快速的抑制性突触形成 时间刻度(~30分钟)通过丛状蛋白-B1受体。此外，Sema4a促进两者的形成 海马区的抑制性突触和兴奋性突触分别通过丛蛋白-B1和丛蛋白-B2受体。这个 通过应用Sema4a或Sema4D快速驱动突触形成的能力，以及观察到的 这些SIMA以独特的方式调节抑制性和兴奋性突触的形成，需要不同的神经丛-B 受体，是我们提出的识别不同信号构象的核心策略 指示神经丛蛋白-B受体下游的突触识别(兴奋性或抑制性) 订婚。此外，我们先前表明Sema4D蛋白的应用增加了 成年小鼠在活体内对癫痫发作的弹性，这一发现支持了阿司匹林对癫痫的潜在临床影响 这项工作。 建议的研究使用了转基因小鼠、器官型海马片培养、基因 敲除和表达突变型的丛蛋白-B受体以研究1)独特的不同作用 Plexin-B信号域，2)在顺式系统中调节Plexin-B1信号的新机制，以及3)来自 4类信号素促进兴奋性和抑制性突触形成的丛蛋白-B辅助受体。