Transduction Mechanisms Mediating Nerve Growth Cone Guidance

介导神经生长锥引导的转导机制

基本信息

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
项目类别：
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

项目摘要

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）：发育中的轴突的生长锥通过感测启动吸引或排斥转向的环境引导线索的梯度来引导轴突延伸穿过细胞外基质（ECM）。趋化生长锥引导在神经系统损伤的情况下也很重要，因为髓磷脂分解释放的因子可能充当化学防护剂并抑制轴突伸长，从而阻止功能恢复。了解介导生长锥引导的分子机制可以为制定增强损伤或神经退行性疾病后再生的策略提供重要见解。细胞质 Ca2+ 信号介导许多引导信号的作用，但表面受体激活与 Ca2+ 信号传导之间的联系在很大程度上尚不清楚。同样，对生长锥趋化性背后的细胞过程的理解仍然不完整。目前的模型严重依赖于细胞骨架重排，但体内研究表明，调节对 ECM 的粘附对于正确引导也至关重要。拟议研究的目标是定义轴突生长锥趋化引导背后的转导机制。具体来说，我们的目标是定义介导细胞外引导信号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延伸方向的下游效应器过程的调节。我们的初步研究结果使我们建立了一个中心假设，即引导信号的生长锥检测是由表面膜上的极化磷酸肌醇 3-激酶 (PI3K) 和 Akt 信号介导的，这会触发局部 Ca2+ 信号并刺激内吞和胞吐机制重新分配ECM 受体和引导信号在生长锥表面不对称，并启动趋化引导。该提案分为四个相互关联的具体目标，这些目标将定义以下内容：首先，PI3K/Akt 信号传导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+ 信号如何调节生长锥转动过程中的囊泡动力学；第四，PI3K/Akt 和 Ca2+ 信号如何在生长锥转动过程中调节整合素和引导受体的运输。这项研究将为介导引导信号检测、引导信号放大以及在趋化生长锥引导过程中控制膜动力学和表面受体重新分布的细胞机制的调节提供新的见解。公共健康相关性：在发育中的神经系统中，神经细胞的生长尖端通过感知启动吸引或排斥转向的引导线索的梯度，穿过复杂的环境基质延伸到适当的目标细胞。这一指导在神经系统损伤的情况下也很重要，因为髓磷脂分解释放的因子可能充当驱虫剂并抑制伸长，从而阻止功能恢复。这项研究的目标是定义介导引导提示检测的信号，并确定这些信号如何调节细胞过程以控制延伸方向。这些发现将有助于我们了解神经系统的发育，并为促进神经退行性疾病或损伤后再生的潜在治疗方法提供见解。