CYTOSKELETAL SIGNALING AND AXON GUIDANCE

描述(摘自申请人摘要)：建立和维护 细胞的形状和极性在多细胞的发展中起着关键作用 有机体。在发育中的神经系统中，神经元将轴突发送到它们的 纠正靶点以形成轴突支架，在其上功能神经元 我们已经建立了联系。轴突是如何被引导到它们的新生靶点的 神经系统？最近的努力表明，细胞外线索提供了指导 信息，并由存在于生长上的跨膜受体检测 锥体，位于延伸轴突远端的感觉运动结构。在……里面 对这种提示的反应，生长锥体的肌动蛋白细胞骨架，它 调节生长锥体移动，被改变以实现定向迁移 生长锥体。许多引导线索及其受体已经被识别出来。较少 已知传递轴突的细胞内信号机制 肌动蛋白细胞骨架的引导信号。在此提出的研究旨在 识别和描述连接轴突的细胞质信号机制 线虫中肌动蛋白细胞骨架的导向受体 优雅女装。UNC-115基因突变导致特定的轴突引导和 外延错误。UNC-115编码一种新的保守的肌动蛋白结合蛋白 可能调节肌动蛋白细胞骨架以响应轴突引导信号。 UNC-115与RAC GTP酶信号在基因上起作用，并在物理上相互作用 用新的WD-40重复蛋白AXM-1进行轴突引导。三个C。 线虫的RAC基因Ced-10、MiG-2和RAC-2定义了三个平行和冗余的基因 调节轴突引导的信号通路。UNC-115在RAC-2中发挥作用 途径，并平行于MiG-2和CED-10。可能的是，UNC-115调制 生长锥体肌动蛋白细胞骨架对引导信号的响应 RAC-2信令和AXM-1。这里描述的实验旨在阐明这一角色 UNC-115在轴突引导信号转导中的作用。第一个目标是确定 通过两种方法筛选与UNC-115共同作用于轴突引导的其他基因 与UNC-115相互作用的现有候选突变体；并利用 RAC基因功能冗余筛选UNC-115中的新突变 利用MiG-2合成轴突缺陷的途径。第二个目标是 描述与UNC-115分子物理相互作用的分子， 包括AXM-1。第三个目的是研究黄曲霉毒素的分子机制 UNC-115的功能是解释在向 生长锥体中的细胞骨架。

DESCRIPTION (From the Applicant's Abstract): The establishment and maintenance of cell shape and polarity play key roles in the development of multicellular organisms. In the developing nervous system, neurons send axons to their correct targets to form an axon scaffold upon which functional neuronal connections are made. How are axons guided to their targets in the nascent nervous system? Recent efforts suggest that extracellular cues provide guidance information and are detected by transmembrane receptors present on the growth cone, the sensory motile structure at the distal tip of an extending axon. In response to such cues, the actin cytoskeleton of the growth cone, which mediates growth cone movement, is altered to achieve directed migration of the growth cone. Many guidance cues and their receptors have been identified. Less is known about the intracellular signaling mechanisms that transmit axon guidance signals to the actin cytoskeleton. The study proposed here aims to identify and characterize cytoplasmic signaling mechanisms that link axon guidance receptors to the actin cytoskeleton in the nematode Caenorhabditis elegans. Mutations in the unc-115 gene cause specific axon guidance and outgrowth errors. Unc-115 encodes a new conserved actin-binding protein that might modulate the actin cytoskeleton in response to axon guidance signals. Unc-115 acts genetically with Rac GTPase signaling and interacts physically with the novel WD-40 repeat protein AXM-1 in axon guidance. The three C. elegans Rac genes, ced-10, mig-2 and rac-2, define three parallel and redundant signaling pathways that mediate axon guidance. Unc-115 acts in the rac-2 pathway and in parallel to mig-2 and ced-10. Possibly, UNC-115 modulates the growth cone actin cytoskeleton in response to guidance cues transmitted through RAC-2 signaling and AXM-1. Experiments described here aim to elucidate the role of unc-115 in axon guidance signal transduction. The first aim is to identify additional genes that act with unc-115 in axon guidance by two means: screening existing candidate mutants for interactions with unc-115; and utilizing the redundancy in Rac gene function to screen for new mutants in the unc-115 pathway by virtue of synthetic axon defects with mig-2. The second aim is to characterize molecules that interact physically with the UNC-115 molecule, including AXM-1. The third aim is to investigate the molecular mechanisms of unc-115 function to elucidate events taking place during signaling to the cytoskeleton in the growth cone.