Mechanisms of filopodia initiation and actin transport

丝状伪足起始和肌动蛋白运输机制

• 批准号: 7156952
• 负责人: GIANLUCA GALLO
• 金额: $ 29.46万
• 依托单位: DREXEL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-12-06 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7156952
• 关键词: Actins; Axon; Axonal Transport; Biological Models; Cell physiology; Cellular Morphology; Complex; Cues; Cytoskeletal Proteins; Cytoskeleton; Development; Disease; Distal; Event; Exhibits; Family; Filament; Filopodia; Fingers; Growth Cones; Guanosine Triphosphate Phosphohydrolases; Hot Spot; Image; In Vitro; Investigation; Life; Maintenance; Mediating; Microfilaments; Microtubules; Morphology; Myosin Type II; Natural regeneration; Nervous System Physiology; Nervous system structure; Neurons; Neurosciences; Pattern; Polymers; Process; Regulation; Relative (related person); Role; Series; Signal Pathway; Signal Transduction; Site; Testing; actin 2; axon growth; axon guidance; base; experimental analysis; monomer; neurodevelopment; neuronal cell body; novel; polymerization; protein transport; rho; synaptic function; synaptogenesis

DESCRIPTION (provided by applicant): Actin filaments and microtubules are dynamic cytoskeletal polymers that have important roles in cell physiology and determine cell morphology. The complex cellular morphology of neurons is directly related to the function of neurons in the nervous system. Thus, neurons provide an excellent model system for investigating the dynamics of the cytoskeleton as it relates to cellular functions. Actin filaments are of fundamental importance to the development and maintenance of connectivity patterns between neurons, and the formation and function of synapses. Neurons constantly deliver new cytoskeletal proteins synthesized in the cell body to the distal axon through axonal transport. The process of axonal transport is required for maintenance of a functional nervous system and is impaired in a variety of disease states. Filopodia are slender finger-like cellular projections that are strictly dependent on actin filaments and are required for axon guidance and synapse formation. Understanding the mechanisms responsible for filopodial initiation is thus of direct relevance to the understanding of regeneration and the maintenance of nervous system function. This proposal presents studies aimed at (1) determining the form (e.g., filaments versus monomers) of actin transport in axons, and (2) determining the actin-based mechanism of filopodia initiation. The form in which cytoskeletal proteins are transported is controversial. From in vitro studies using neurons transfected with EGFP-actin, we provide preliminary descriptive evidence suggestive of the transport of actin filaments and experimental evidence in favor of the transport of monomeric actin. A series of studies is detailed to experimentally test the hypothesis that actin filaments are the form of actin transport. Additionally, based on live imaging of EGFP-actin in axons and growth cones we have identified the presence of spontaneously formed actin puncta that serve as precursors to filopodial formation. These observations provide a model system for investigating the dynamic cytoskeletal basis of filopodial formation in living neurons. We present studies aimed at determining the role of extra-cellular signals, signaling pathways, and microtubules in regulating the earliest events in filopodial initiation.

描述（由申请人提供）： 肌动蛋白丝和微管是动态细胞骨架聚合物，在细胞生理中具有重要作用并确定细胞形态。神经元的复杂细胞形态与神经元在神经系统中的功能直接相关。因此，神经元提供了一个出色的模型系统，用于研究与细胞功能有关的细胞骨架的动力学。肌动蛋白细丝对于神经元之间的连通性模式以及突触的形成和功能至关重要。神经元通过轴突转运不断传递细胞体中轴突合成的新细胞骨架蛋白。维持功能性神经系统需要轴突运输的过程，并且在多种疾病状态下受到损害。丝状卵形是细长的手指样细胞投影，严格取决于肌动蛋白丝，是轴突引导和突触形成所必需的。因此，了解负责丝虫开始的机制与对再生的理解和维持神经系统功能是直接相关的。该提案介绍了针对（1）确定轴突中肌动蛋白转运的形式（例如，丝与单体）的研究，以及（2）确定基于肌动蛋白的丝状启动机制。细胞骨架蛋白的转运形式是有争议的。从使用EGFP-肌动蛋白转染的神经元的体外研究中，我们提供了初步的描述性证据，暗示了肌动蛋白丝的运输和实验证据，以支持单体肌动蛋白的运输。详细详细介绍了一系列研究，以测试肌动蛋白是肌动蛋白转运的形式的假设。此外，基于轴突和生长锥中eGFP-肌动蛋白的实时成像，我们已经确定了自发形成的肌动蛋白点的存在，这些肌动蛋白点是丝状形成的前体。这些观察结果提供了一个模型系统，用于研究活神经元中丝源形成的动态细胞骨架基础。我们提出的研究旨在确定细胞外信号，信号通路和微管在调节丝虫起始中最早事件中的作用。