Molecular anatomy of Drosophila neuromuscular synapse development

果蝇神经肌肉突触发育的分子解剖学

基本信息

批准号：
15500228
负责人：
SUZUKI Emiko
金额：
$ 2.37万
依托单位：
National Institute of Genetics (2004-2005)The University of Tokyo (2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Establishment of neural networks is based on the target specificity of synaptic connection. The goal of this research project is to elucidate the mechanism that ensures the specific synaptic connectivity. We chose, as a model system, Drosophila embryonic neuromuscular junctions, that constitute relatively simple neural circuits enabling single-cell analyses. By the detailed morphological observation of the stages when an axonal growth cone approaches its target, we found the dynamic interactions of filopodia extending from muscles (myopodia) and neurofiopodia that converge together into a cluster at a definite position for synaptogenesis. The expression of Ezrin-DN in a muscle disturbed cluster formation, leading to abnormal extension of neurites and abortive synaptogenesis. Next, we asked whether the synaptic scaffolding protein PSD-95/Dlg is required in the cluster for proceeding of synaptogenesis. We found that PSD-95/Dlg accumulates in the cluster from the beginning of its formation, and that the expression of Dlg-DN that disturbs endogenous Dig completely blocks the synaptogenesis after the cluster formation. These results indicate that the filopodial clustering plays a pivotal role in synaptogenesis at the right place of a target cell by recruitment of PSD-95/Dlg. Based on these findings, we started a reverse genetic screen for the search of cell-surface proteins involved in the regulation of filopodial clustering that leads to the target-specific synapse formation. By the ectopic expression screening, we have selected about 40 candidate proteins so far. We plan to pursue functional studies on these proteins to elucidate further the mechanism for the synaptogenesis.

神经网络的建立基于突触连接的目标特异性。该研究项目的目的是阐明确保特定突触连通性的机制。我们选择作为模型系统，是果蝇胚胎神经肌肉连接，构成了相对简单的神经回路，可实现单细胞分析。通过对轴突生长锥接近其靶标的阶段的详细形态学观察，我们发现丝状虫从肌肉（肌瘤）和神经嗜性疾病中延伸的动态相互作用，这些相互作用是在明确的突发发生位置的群集中融合成簇的簇。 ezrin-dn在肌肉扰动的簇形成中的表达，导致神经突的异常延伸和流产的突触发生。接下来，我们询问突触蛋白PSD-95/DLG是否需要在群集中进行突触发生。我们发现，PSD-95/DLG从其形成的开头积聚在簇中，并且干扰内源性挖掘的DLG-DN的表达完全阻止了簇形成后的突触发生。这些结果表明，通过募集PSD-95/dlg，丝虫聚类在目标细胞正确位置的突触发生中起关键作用。基于这些发现，我们开始了一个反向遗传筛选，以搜索参与调节丝状聚类的细胞表面蛋白，从而导致目标特异性突触形成。通过异位表达筛选，到目前为止，我们选择了大约40种候选蛋白。我们计划对这些蛋白质进行功能研究，以进一步阐明突触发生的机制。