Cytoskeletal Signaling and Axon Guidance

细胞骨架信号传导和轴突引导

• 批准号: 7812426
• 负责人: Erik A Lundquist
• 金额: $ 36万
• 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 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7812426
• 关键词: Actins; Address; Affect; Axon; Caenorhabditis elegans; Complement; Complex; Cytoskeleton; Defect; Development; Disease; Distal; Event; Filopodia; Genes; Genetic; Goals; Grant; Growth Cones; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; Individual; Life; Link; Mental Retardation; Microfilaments; Molecular; Molecular Genetics; Morphogenesis; Morphology; Nervous system structure; Neurons; Pathway interactions; Phosphotransferases; Proteins; Regulation; Research Design; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Source; Stroke; Structure; System; Testing; abstracting; axon guidance; axon regeneration; cellular imaging; central nervous system injury; design; genetic analysis; in vivo; insight; loss of function mutation; mutant; nervous system development; receptors for activated C kinase; research study; scaffold

Abstract The migrating growth cone at the distal axon tip senses and responds to guidance information. Growth cones display dynamic lamellipodial and filopodial protrusions that are involved in outgrowth and guidance. The aim of these studies is to use C. elegans to understand the cytoskeletal signaling networks that link axon guidance signals to changes in growth cone morphology and outgrowth via the actin cytoskeleton. Results from the previous grant period showed that three actin-regulatory systems, Arp2/3, UNC-115/abLIM, and UNC-34/Enabled, redundantly control axon pathfinding. The Arp2/3 complex and UNC-115/abLIM act redundantly downstream of Rac GTPases and in parallel to UNC-34/Enabled. Each of these molecules controlled the formation of growth cone filopodia, possibly explaining axon pathfinding defects in mutants. That multiple actin regulatory systems contribute to axon guidance and the formation of growth cone filopodia explains the genetic redundancy often observed in studies of axon guidance. In order to understand the molecular events in the growth cone that regulate actin structure, it will be important to understand how these individual actin regulatory networks function and how they interact in growth cone outgrowth and guidance. In this proposal, genetic, molecular, and in vivo cellular imaging approaches will be used to dissect the roles of cytoskeletal signaling pathways in growth cone morphology and outgrowth. Many pathways and molecules have been identified that affect axon pathfinding. These experiments move beyond the "gene by gene" approach to studying axon pathfinding and instead are designed to understand how molecules relate to one another in pathways and networks to control axon pathfinding and growth cone morphology. To complement the genetic analyses, in vivo cellular imaging studies are designed to understand the unique or overlapping contributions of the often genetically-redundant pathways to growth cone morphogenesis in a developmental context. The focus of the proposal is the idea that the CDC-42 GTPase acts upstream of Rac GTPases in axon pathfinding. Experiments to characterize molecules that regulate CDC-42 and those that might link CDC-42 to Rac signaling are proposed. The first and second aims aim test the idea that CDC-42 acts upstream of Rac GTPases in axon pathfinding. The third aim is to probe the role of the MIG-15 NIK kinase and RACK-1/Receptor for activated C kinase and their interaction with UNC-115/abLIM downstream of CDC-42 in a Rac-independent pathway. The fourth aim integrates the first three and is to characterize the effects of these pathways on growth cone filopodia formation and morphology during outgrowth. The results of these experiments will significantly contribute to the goal of understanding the cytoskeletal signaling networks involved in growth cone morphology and will begin to address the cellular roles of these distinct pathways in axon development.

抽象的 远端轴突尖端的迁移生长锥感知引导信息并做出反应。生长锥显示出参与生长和引导的动态片状伪足和丝状伪足突起。 这些研究的目的是利用线虫来了解细胞骨架信号网络，该网络将轴突引导信号与生长锥形态的变化和通过肌动蛋白细胞骨架的生长联系起来。上一个资助期的结果表明，三个肌动蛋白调控系统，Arp2/3、UNC-115/abLIM 和 UNC-34/Enabled，冗余地控制轴突寻路。 Arp2/3 复合体和 UNC-115/abLIM 在 Rac GTPases 下游冗余地发挥作用，并与 UNC-34/Enabled 并行。这些分子中的每一个都控制着生长锥丝状伪足的形成，这可能解释了突变体中轴突寻路缺陷。多个肌动蛋白调节系统有助于轴突引导和生长锥丝状伪足的形成，这解释了轴突引导研究中经常观察到的遗传冗余。为了了解生长锥中调节肌动蛋白结构的分子事件，了解这些单独的肌动蛋白调节网络如何发挥作用以及它们如何在生长锥生长和引导中相互作用非常重要。在该提案中，遗传、分子和体内细胞成像方法将用于剖析细胞骨架信号通路在生长锥形态和生长中的作用。已经确定了许多影响轴突寻路的途径和分子。这些实验超越了“逐个基因”的方法来研究轴突寻路，而是旨在了解分子如何在路径和网络中相互关联，以控制轴突寻路和生长锥形态。为了补充遗传分析，体内细胞成像研究旨在了解发育背景下生长锥形态发生中通常遗传冗余的途径的独特或重叠的贡献。该提案的重点是 CDC-42 GTPase 在轴突寻路中作用于 Rac GTPase 的上游。 提议进行实验来表征调节 CDC-42 的分子以及可能将 CDC-42 与 Rac 信号传导联系起来的分子。第一个和第二个目标旨在测试 CDC-42 在轴突寻路中作用于 Rac GTPases 上游的想法。第三个目标是探讨 MIG-15 NIK 激酶和 RACK-1/RACK-1/RACK-1/受体对激活的 C 激酶的作用以及它们与 CDC-42 下游的 UNC-115/abLIM 在 Rac 独立途径中的相互作用。第四个目标整合了前三个目标，是表征这些途径对生长过程中生长锥丝状伪足形成和形态的影响。这些实验的结果将极大地有助于理解参与生长锥形态的细胞骨架信号网络的目标，并将开始解决这些不同途径在轴突发育中的细胞作用。