The Cytoskeleton of the Frog Motor Nerve Terminal

为了使神经系统正常运作，每个神经细胞必须在其靶细胞上的精确位置组装释放其信号（神经递质）所需的分子机器，在该位置可以接收信号并产生反应。 神经末梢的释放机制与其靶点的受体分子之间的这种精确的结构对准不仅对其构建和生长提出了挑战，而且对其维护和保养也提出了挑战。 神经细胞和目标之间的这种组织的精确性在青蛙的神经肌肉接头中得到了很好的说明，在那里，神经末梢中的线性释放位点被不同的非释放域分开。 利用青蛙运动神经末梢，康纳博士实验室最近发现，包括F-肌动蛋白在内的细胞骨架丝集中在非释放区。 我们的目标是确定的作用，细胞骨架和F-肌动蛋白的神经末梢的基本过程中，可能会发生在nonrelease域：神经递质释放机制的回收和稳定的神经末梢在其目标。 康纳博士的研究小组和斯坦福大学的合作者将使用电子显微镜断层扫描技术构建运动神经末梢非释放区域细胞骨架的高分辨率三维图。 这样的图谱将是所有研究人员的宝贵资源，并将允许对一系列解决神经末梢功能的实验进行结构解释。研究人员还将测试非释放域中的细胞骨架元件是否参与神经末梢刺激后释放机制的重新捕获。 最后，还将进行实验以确定终末许旺细胞在组织神经末梢中的F-肌动蛋白中的作用，以及在神经末梢的发育、再生和断开连接的过程中，F-肌动蛋白在神经末梢中的分布如何变化。 该项目还将确定细胞骨架在稳定靶神经末梢方面的重要性。 这些实验将为我们理解神经细胞与其目标之间的联系的功能和维持提供关键信息。 在更广泛的范围内，该项目将为本科生提供学年和夏季参与研究的机会。 此外，研究生将在该项目期间接受培训，他们将有机会指导本科生并在国家会议上介绍他们的成果。

For proper functioning of the nervous system, each nerve cell must assemble the molecular machinery required for the release of its signal, the neurotransmitter, at the precise location on its target cell where the signal can be received and a response produced. This precise structural alignment between the release machinery of nerve terminals and the reception molecules of their targets presents a challenge not only for its construction and growth but also for its upkeep and maintenance. The precision of this organization between nerve cells and targets is beautifully illustrated at the frog neuromuscular junction where a linear array of release sites in nerve terminals are separated by distinct nonrelease domains. Using the frog motor nerve terminal, Dr. Connor laboratory recently discovered that cytoskeletal filaments including F-actin, are concentrated in nonrelease domains. The goal is to determine the role of the cytoskeleton and F-actin in fundamental processes of nerve terminals that may occur in nonrelease domains: the recycling of the neurotransmitter release machinery and the stabilization of nerve terminals at their targets. Dr. Connor's group and collaborators at Stanford University, will use electron microscope tomography to construct a high-resolution three-dimension map of the cytoskeleton in nonrelease domains of motor nerve terminals. Such a map will be a valued resource for all researchers, and will allow the structural interpretation of a range of experiments that address nerve terminal function. The investigators will also test whether cytoskeletal elements in nonrelease domains participate in the recapture of the release machinery after stimulation of nerve terminals. Finally, the experiments will also be conducted to determine the role of the terminal Schwann cell in organizing the F-actin in nerve terminals, and how the F-actin distribution in nerve terminals changes in the process of developing, regrowing, and breaking connections. This project will also determine the importance of the cytoskeleton in stabilizing nerve terminals at their targets. These experiments will provide information critical for our understanding of the functioning and maintenance of contacts between nerve cells and their targets. In a broader scope, this project will provide both academic year and summer opportunities for undergraduates to participate in research. Further, graduate students will be trained during this project and they will have the opportunity to mentor undergraduates and present their results at national meetings.