Cytoskeletal Signaling and Axon Guidance

细胞骨架信号传导和轴突引导

• 批准号: 6970114
• 负责人: Erik A Lundquist
• 金额: $ 31.02万
• 依托单位: UNIVERSITY OF KANSAS LAWRENCE
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-01-18 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6970114
• 关键词: Caenorhabditis elegans; actin binding protein; actins; biological signal transduction; cell cell interaction; cell morphology; cell motility; cellular polarity; cytoskeleton; developmental genetics; developmental neurobiology; fibroblasts; fluorescence microscopy; gene mutation; genetic library; genetic mapping; genetic screening; growth cones; guanine nucleotide exchange factors; guanosinetriphosphatases; neuronal guidance; protein binding; protein structure function; yeast two hybrid system

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. This proposal involves mechanisms of axonal pathfinding to their targets in the nascent nervous system. 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. Our studies in Caenorhabditis elegans have revealed that three Rac GTPases define three redundant cytoskeletal signaling pathways in axon pathfinding, and that the GTP exchange factor UNC-73 Trio controls all three pathways. We have found that the actin-binding protein UNC-115 acts downstream of one of the three Rac pathways, possibly to directly modulate actin structure in response to Rac signaling. Further, we have identified a novel Rac regulator, the 7-WD repeat protein SWR-1, which directly binds to both UNC-115 and Racs and represses Rac activity in neuronal morphogenesis. Experiments described here aim to elucidate the role of Rac signal transduction in axon pathfinding, including identification and characterization of new molecules in Rac signaling and analyses of how these molecules relate to one another in axon pathfinding. The first aim is to characterize the role of the novel DAD domain in the function of the downstream Rac cytoskeletal effector UNC-115 in axon pathfinding. The second aim is to determine the molecular mechanisms of Rac repression by the Rac negative regulator SWR-1. The third aim is to identify and characterize new molecules and interactions with Rac signaling by exploiting the redundancy of Rac function in axon pathfinding. Understanding the molecular mechanisms of cytoskeletal signaling could prove critical for developing therapies aimed at mitigating the effects of central nervous system trauma (e.g. spinal cord injury and stroke) as well as tumor metastasis

细胞形状和极性的建立和维护在多细胞生物的发展中起关键作用。在发育中的神经系统中，神经元将轴突发送到其正确的靶标，形成轴突支架，在该轴突上进行了功能性神经元连接。该建议涉及在新生神经系统中轴突探路的机制。细胞外提示提供指导信息，并通过生长锥上存在的跨膜受体（延伸轴突远端的感觉运动结构）检测到。为了响应这种提示，介导生长锥运动的生长锥的肌动蛋白细胞骨架被改变以实现生长锥的定向迁移。我们在秀丽隐杆线虫的研究表明，三个RAC GTPase定义了轴突途径中的三个冗余细胞骨架信号通路，而GTP交换因子UNC-73三重奏三重奏控制了所有三个途径。我们发现，肌动蛋白结合蛋白UNC-115作用于三种RAC途径之一的下游，可能是为了响应RAC信号传导而直接调节肌动蛋白结构。此外，我们已经确定了一种新型的RAC调节剂，即7-WD重复蛋白SWR-1，该蛋白SWR-1直接与UNC-115和RACS结合，并在神经元形态发生中抑制RAC活性。此处描述的实验旨在阐明RAC信号转导在轴突探测过程中的作用，包括在RAC信号传导中鉴定和表征新分子的鉴定和表征，以及这些分子如何在轴突探路中相互关系的分析。第一个目的是表征新型DAD域在轴突路径中下游RAC细胞骨架效应unc-115的功能中的作用。第二个目的是确定RAC负调节剂SWR-1的RAC抑制的分子机制。第三个目的是通过利用轴突理化功能的冗余性来识别和表征与RAC信号传导的相互作用。了解细胞骨架信号传导的分子机制可能对开发旨在减轻中枢神经系统创伤的影响（例如脊髓损伤和中风）以及肿瘤转移的疗法至关重要。