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，在细胞生理学和决定细胞形态中具有重要作用。神经元复杂的细胞形态与神经系统中神经元的功能直接相关。因此，神经元为研究与细胞功能相关的细胞骨架动力学提供了一个极好的模型系统。肌动蛋白丝对于神经元之间连接模式的发展和维持以及突触的形成和功能至关重要。神经元不断地将细胞体内合成的新细胞骨架蛋白通过轴突运输输送到远端轴突。轴突运输过程是维持功能性神经系统所必需的，并且在多种疾病状态下都会受到损害。丝状伪足是细长的手指状细胞突起，严格依赖于肌动蛋白丝，是轴突引导和突触形成所必需的。因此，了解丝状伪足起始的机制与了解再生和神经系统功能的维持直接相关。该提案提出的研究旨在（1）确定轴突中肌动蛋白运输的形式（例如，丝与单体），以及（2）确定基于肌动蛋白的丝状伪足起始机制。细胞骨架蛋白的运输形式存在争议。通过使用 EGFP-肌动蛋白转染神经元的体外研究，我们提供了提示肌动蛋白丝转运的初步描述性证据和有利于单体肌动蛋白转运的实验证据。一系列研究详细地通过实验检验了肌动蛋白丝是肌动蛋白运输形式的假设。此外，根据轴突和生长锥中 EGFP-肌动蛋白的实时成像，我们发现了自发形成的肌动蛋白点的存在，它是丝状伪足形成的前体。这些观察结果为研究活神经元丝状伪足形成的动态细胞骨架基础提供了一个模型系统。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状伪足起始最早事件中的作用。