Cell-intrinsic mechanisms of presynaptic assembly

PI：Kurshan，Peri T. 项目概要/摘要 突触是大脑中基本的信息处理单元，它们的功能障碍导致 神经发育和神经精神障碍。突触的发育和组织是由 一部分是由一类称为突触细胞粘附分子（sCAM）的跨膜蛋白引起的， sCAM基因与自闭症、精神分裂症和智力残疾等疾病高度相关， 还有其他的突触形成的主导模型表明，它是由跨突触启动的。 结合的sCAM，然而，在体内的证据，该模型是缺乏的。在这里，我们建议揭露非跨性别者 突触前组装的突触细胞内在分子程序，介导定位，运输和 sCAM和其他整合的突触前蛋白的亚细胞功能。 我们的初步证据表明，突触前sCAMs neurexin和 SYG-2/nephrin是突触前组织细胞自主需要的。此外，我们发现， neurexin在突触前活动区的定位是通过与活动区的细胞内相互作用介导的 支架蛋白和驱动蛋白马达。最后，我们发现sCAM和其他活性物质的依赖性 区带蛋白对驱动蛋白运输的影响取决于轴突生长的阶段。基于这些发现，我们 假设突触前组装在很大程度上是由细胞内在机制介导的。我们建议 追求三个具体的目标，以表征管理机制（1）细胞内招募 sCAM，（2）通过sCAM介导的细胞骨架， 重排，和（3）通过驱动蛋白的sCAM和其他活性区蛋白的递送和重新分配。 依赖和独立的机制在不同阶段的轴突生长（目的3）。 为了研究这些假设，我们利用遗传的易驾驭性和刻板的神经系统， 线虫C.优雅，沿着创新的成像和遗传方法。C. elegans有一个长 揭示基础突触生物学的历史和我们以前发表的结果和初步数据 使我们能够很好地利用这个系统的力量。总的来说，我们的研究将揭示 细胞内在机制如何控制sCAM在突触形成中的功能。这些研究有 有可能揭示神经发育障碍的分子机制， sCAM功能的缺陷，从而为开发特异性治疗干预提供了靶点。

PI: Kurshan, Peri T. PROJECT SUMMARY/ABSTRACT Synapses are the fundamental information processing units in the brain and their dysfunction leads to neurodevelopmental and neuropsychiatric disorders. Synapse development and organization is mediated in part by a class of transmembrane proteins called synaptic cell-adhesion molecules (sCAMs), and mutations in sCAM genes is highly associated with diseases such as autism, schizophrenia and intellectual disability, among others. The dominant model for synapse formation suggests that it is initiated by the trans-synaptic binding of sCAMs, however in vivo evidence for that model is lacking. Here we propose to uncover non-trans- synaptic cell-intrinsic molecular programs for presynaptic assembly that mediate the localization, trafficking and subcellular functions of sCAMs and other integral presynaptic proteins. Our preliminary evidence suggests that the intracellular domains of the presynaptic sCAMs neurexin and syg-2/nephrin are cell-autonomously required for presynaptic organization. Moreover, we find that the localization of neurexin to the presynaptic active zone is mediated by intracellular interactions with active zone scaffold proteins and kinesin motors. Finally, we have found that the dependence of sCAMs and other active zone proteins on transport by kinesins depends on the stage of axonal outgrowth. Based on these findings, we hypothesize that presynaptic assembly is mediated in large part by cell-intrinsic mechanisms. We propose to pursue three Specific Aims to characterize the mechanisms that govern (1) the intracellular recruitment of sCAMs, (2) the intracellular organization of proper synapse spacing by sCAM-mediated cytoskeletal rearrangement, and (3) the delivery and reallocation of sCAMs and other active zone proteins by kinesin- dependent and independent mechanisms at different stages of axonal outgrowth (Aim 3). To investigate these hypotheses, we leverage the genetic tractability and stereotyped nervous system of the nematode C. elegans, along with innovative imaging and genetic approaches. C. elegans has a long history of revealing fundamental synaptic biology and our previous published results and preliminary data position us well to take advantage of the power of this system. Collectively our proposed research will reveal how cell-intrinsic mechanisms govern the function of sCAMs in synapse formation. These studies have the potential to uncover the molecular mechanisms underlying neurodevelopmental disorders that result from defects in sCAM function, and thus provide targets for the development of specific therapeutic interventions.