Transduction Mechanisms Mediating Nerve Growth Cone Guidance

介导神经生长锥引导的转导机制

• 批准号: 8134805
• 负责人: John Richard Henley
• 金额: $ 33.81万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8134805
• 关键词: Address; Adhesions; Axon; Biological Assay; Biological Models; Biosensor; Brain-Derived Neurotrophic Factor; Cell membrane; Cell physiology; Cells; Chemotactic Factors; Chemotaxis; Chimeric Proteins; Complex; Cues; DNA Sequence Rearrangement; Detection; Dominant-Negative Mutation; Dyes; Dynamin; ECM receptor; Endocytosis; Exocytosis; Extracellular Matrix; Feedback; Goals; Growth Cones; Image; Immunoassay; In Vitro; Injury; Integrins; Label; Life; Link; Mediating; Membrane; Methods; Microscopic; Modeling; Molecular; Myelin; Myelin Associated Glycoprotein; Natural regeneration; Nerve; Nervous System Trauma; Nervous system structure; Neurodegenerative Disorders; Neurons; Oligonucleotides; Phosphatidylinositols; Phosphotransferases; Process; Proteins; Receptor Activation; Recovery of Function; Recycling; Regulation; Research; Role; Signal Transduction; Signal Transduction Pathway; Spinal; Surface; Therapeutic; Total Internal Reflection Fluorescent; Vesicle; Xenopus; axon growth; axon guidance; base; cell growth regulation; cellular imaging; extracellular; fluorescence imaging; human NTN1 protein; in vivo; insight; mutant; nervous system development; netrin-1; novel; phosphatidylinositol 3,4,5-triphosphate; prevent; public health relevance; receptor; release factor; trafficking; Address; Adhesions; Axon; Biological Assay; Biological Models; Biosensor; Brain-Derived Neurotrophic Factor; Cell membrane; Cell physiology; Cells; Chemotactic Factors; Chemotaxis; Chimeric Proteins; Complex; Cues; DNA Sequence Rearrangement; Detection; Dominant-Negative Mutation; Dyes; Dynamin; ECM receptor; Endocytosis; Exocytosis; Extracellular Matrix; Feedback; Goals; Growth Cones; Image; Immunoassay; In Vitro; Injury; Integrins; Label; Life; Link; Mediating; Membrane; Methods; Microscopic; Modeling; Molecular; Myelin; Myelin Associated Glycoprotein; Natural regeneration; Nerve; Nervous System Trauma; Nervous system structure; Neurodegenerative Disorders; Neurons; Oligonucleotides; Phosphatidylinositols; Phosphotransferases; Process; Proteins; Receptor Activation; Recovery of Function; Recycling; Regulation; Research; Role; Signal Transduction; Signal Transduction Pathway; Spinal; Surface; Therapeutic; Total Internal Reflection Fluorescent; Vesicle; Xenopus; axon growth; axon guidance; base; cell growth regulation; cellular imaging; extracellular; fluorescence imaging; human NTN1 protein; in vivo; insight; mutant; nervous system development; netrin-1; novel; phosphatidylinositol 3,4,5-triphosphate; prevent; public health relevance; receptor; release factor; trafficking

DESCRIPTION (provided by applicant): The growth cone of developing axons guides axon extension through the extracellular matrix (ECM) by sensing gradients of environmental guidance cues that initiate attractive or repulsive steering. Chemotactic growth cone guidance is also important in the context of nervous system injury, as factors released from the breakdown of myelin may act as chemorepellents and inhibit axon elongation, thereby preventing functional recovery. Understanding the molecular mechanisms that mediate growth cone guidance could provide important insights for developing strategies to enhance regeneration after injury or neurodegenerative disease. Cytoplasmic Ca2+ signals mediate the action of many guidance cues, but the link between surface receptor activation and Ca2+ signaling is largely unknown. Likewise, an understanding of the cellular processes underlying growth cone chemotaxis remains incomplete. Current models rely heavily on cytoskeletal rearrangements, but in vivo studies have demonstrated that regulated adhesion to the ECM is also critical for proper guidance. The goal of the proposed research is to define the transduction mechanisms underlying the chemotactic guidance of axonal growth cones. Specifically, we aim to define the intracellular signals that mediate growth cone detection of extracellular guidance cues, the interactions between early signal transduction pathways, and the regulation of downstream effector processes that control the direction of axon extension. Our preliminary findings have led us to establish a CENTRAL HYPOTHESIS that growth cone detection of guidance cues is mediated by polarized phosphoinositide 3-kinase (PI3K) and Akt signaling at the surface membrane, which triggers local Ca2+ signals and stimulates endocytic and exocytic machinery to redistribute receptors for ECM and guidance cues asymmetrically at the growth cone surface and initiate chemotactic guidance. The proposal is organized into four interrelated specific aims that will define the following: first, the role of PI3K/Akt signaling in mediating growth cone chemotaxis; second, how PI3K/Akt signaling activates Ca2+ guidance signals in the growth cone; third, how PI3K/Akt and Ca2+ signaling regulate vesicle dynamics during growth cone turning; and fourth, how PI3K/Akt and Ca2+ signaling regulate trafficking of integrin and guidance receptors during growth cone turning. This study will provide novel insights into the early signals that mediate the detection of guidance cues, the amplification of guidance signals, and the regulation of cellular machinery that controls membrane dynamics and the redistribution of surface receptors during chemotactic growth cone guidance. PUBLIC HEALTH RELEVANCE: In the developing nervous system the growing tip of nerve cells extends through a complex environmental matrix to the appropriate target cells by sensing gradients of guidance cues that initiate attractive or repulsive steering. This guidance is also important in the context of nervous system injury, as factors released from the breakdown of myelin may act as repellents and inhibit elongation, thereby preventing functional recovery. The goal of this research is to define signals that mediate the detection of guidance cues and determine how these signals regulate cellular processes to control the direction of extension. The findings will contribute to our understanding of the development of the nervous system and provide insights into potential therapeutic approaches for promoting regeneration after neurodegenerative disease or injury.

描述（由申请人提供）：开发轴突的生长锥通过感应引发有吸引力或排斥转向的环境引导线索的梯度通过细胞外基质（ECM）引导轴突延伸。在神经系统损伤的背景下，趋化性生长锥引导也很重要，因为髓磷脂的崩溃释放的因素可能充当化学物质并抑制轴突伸长，从而防止功能恢复。了解介导生长锥引导的分子机制可以为制定策略增强损伤或神经退行性疾病的再生提供重要见解。细胞质Ca2+信号介导了许多引导线索的作用，但是表面受体激活与Ca2+信号传导之间的联系在很大程度上是未知的。同样，对生长锥趋化性基础的细胞过程的理解仍然不完整。当前的模型在很大程度上依赖于细胞骨架重排，但是体内研究表明，对ECM的粘附对于适当的指导也至关重要。拟议的研究的目的是定义轴突生长锥趋化引导的基础的转导机制。具体而言，我们旨在定义介导细胞外引导提示的生长锥检测的细胞内信号，早期信号转导途径之间的相互作用以及控制轴突扩展方向的下游效应器过程的调节。 Our preliminary findings have led us to establish a CENTRAL HYPOTHESIS that growth cone detection of guidance cues is mediated by polarized phosphoinositide 3-kinase (PI3K) and Akt signaling at the surface membrane, which triggers local Ca2+ signals and stimulates endocytic and exocytic machinery to redistribute receptors for ECM and guidance cues asymmetrically at the growth cone surface and启动趋化指导。该提案被组织为四个相互关联的特定目的，这些目标将定义以下内容：首先，PI3K/AKT信号在介导生长锥趋化性中的作用；其次，PI3K/AKT信号如何激活生长锥中的Ca2+引导信号；第三，PI3K/AKT和Ca2+信号传导如何调节生长锥转盘的囊泡动力学；第四，PI3K/AKT和Ca2+信号传导如何调节整联蛋白和引导受体在生长锥转动过程中的运输。这项研究将提供新的见解，以介绍介导引导提示的检测，引导信号的扩增以及控制膜动力学的细胞机械的调节以及在趋化生长锥引导过程中表面受体的重新分布。 公共卫生相关性：在发育中的神经系统中，不断增长的神经细胞尖端通过感知引发有吸引力或排斥转向的指导线索的梯度，从而延伸到适当的目标细胞的复杂环境矩阵。在神经系统损伤的背景下，该指南也很重要，因为髓磷脂崩溃而释放的因素可能充当驱虫剂并抑制伸长，从而防止功能恢复。这项研究的目的是定义介导检测引导线索的信号，并确定这些信号如何调节细胞过程以控制扩展方向。这些发现将有助于我们理解神经系统的发展，并提供对神经退行性疾病或损伤后促进再生的潜在治疗方法的见解。