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持在多细胞生物的发育中起着关键作用。在发育中的神经系统中，神经元将轴突发送到其正确的目标以形成轴突支架，在该支架上进行功能性神经元连接。这个提议涉及轴突在新生神经系统中找到其靶点的机制。细胞外信号提供指导信息，并被存在于生长锥上的跨膜受体检测到，生长锥是延伸轴突远端的感觉运动结构。响应于这样的线索，生长锥的肌动蛋白细胞骨架，其介导生长锥运动，被改变以实现生长锥的定向迁移。我们在秀丽隐杆线虫中的研究揭示了三种Rac GTP酶在轴突寻路中定义了三种冗余的细胞骨架信号通路，并且GTP交换因子β-73 Trio控制着所有三种通路。我们已经发现肌动蛋白结合蛋白Rac-115作用于三条Rac通路之一的下游，可能直接调节肌动蛋白结构以响应Rac信号传导。此外，我们已经确定了一种新的Rac调节剂，7-WD重复蛋白SWR-1，它直接结合到两个ESTA-115和Racs和抑制Rac活性在神经元形态发生。本文描述的实验旨在阐明Rac信号转导在轴突寻路中的作用，包括Rac信号转导中的新分子的鉴定和表征以及这些分子在轴突寻路中如何相互关联的分析。第一个目的是表征新的DAD结构域在下游Rac细胞骨架效应子cytoskeleton-115在轴突寻路中的功能中的作用。第二个目的是确定Rac负调节因子SWR-1抑制Rac的分子机制。第三个目标是通过利用轴突寻路中Rac功能的冗余来识别和表征新分子以及与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对于开发旨在减轻中枢神经系统创伤（例如脊髓损伤和中风）以及肿瘤转移的影响的疗法至关重要