L1 Interactions in Retino-Collicular Targeting

视网膜-丘脑靶向中的 L1 相互作用

• 批准号: 0618176
• 负责人: Patricia Maness
• 金额: --
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-15 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0618176&HistoricalAwards=false
• 关键词: L1; Interactions; Retino; Collicular; Targeting

Abstract Guidance and targeting of neuronal axons from the eye to the brain is orchestrated through a diverse set of cues by molecular mechanisms that are just beginning to be elucidated. This proposal focuses on the mechanism by which the neural cell adhesion molecule L1, regulates the retinotopic map of retinal ganglion cell axons to targets in the brain. The specific hypothesis to be tested is that L1 linkage to the cytoskeleton through ankyrin is an esssential mechanistic determinant by which ganglion cell axons are mapped to topographically specific targets in the superior colliculus to specify visual connectivity. The role of L1 interactions with the neuronal cytoskeleton in synaptic targeting will be tested in a novel L1 mutant mouse L1(Y1229H), which lacks the capability to bind ankyrin, an adapter that links L1 to the actin cytoskeleton. This mutant is the first example of a point mutation disrupting a specific cytoskeletal linkage that perturbs topographic axon mapping. In Aim 1 axon tracing of retinal ganglion cell axons to topographic targets in the superior colliculus of L1(Y1229H) knock-in mice will be carried out to define the pattern of retinotopic mapping along both the anteroposterior and mediolateral axes in order to obtain insight into the role of L1 anchorage to the cytoskeleton in axonal outgrowth and synaptic targeting. In Aim 2, cellular and biochemical assays will identify the protein interactions governed by L1 binding to the cytoskeleton necessary for axonal targeting and synaptic contact formation. Specific experiments are designed to analyze L1-ankyrin binding effects on modulation of integrin-dependent cell adhesion and attractive or repulsive axon guidance to ephrins and Eph receptors (both A and B classes). The interaction of L1 neural adhesion molecules with ankyrin and ephrin/Eph receptors is a novel concept that will advance a molecular understanding of mechanisms that regulate neuronal wiring. This study has broad significance for understanding fundamental mechanisms of neuronal wiring, because L1 is the prototype of a family of adhesion receptors that are widely expressed in the brain, where they may mediate synaptic connections through different ankyrin isoforms. Educational benefits will include training of 2 undergraduates, 2 graduate students, and a postdoctoral scientist. The grant will increase the participation of women in research, enhancing diversity and minority representation, as all of the trainees are women. General benefits to the society at large will include provision of new knowledge that will increase understanding of fundamental mechanisms of neuronal connectivity. This knowledge will impact broadly on larger areas of nerve regeneration and nerve grafting, and may suggest new means to improve the life and health of animals and human beings.

神经轴突从眼睛到大脑的引导和靶向是通过一系列不同的分子机制来协调的，这些分子机制刚刚开始被阐明。本研究的重点是神经细胞粘附分子L1调控视网膜神经节细胞轴突向脑内靶点的视网膜定位图的机制。需要验证的具体假设是，L1通过锚蛋白连接到细胞骨架是一个重要的机制决定因素，通过该机制，神经节细胞轴突被映射到上丘的地形特异性靶点，以指定视觉连通性。L1与神经元细胞骨架相互作用在突触靶向中的作用将在一种新的L1突变小鼠L1（Y1229H）中进行测试，L1缺乏结合锚蛋白的能力，锚蛋白是一种连接L1与肌动蛋白细胞骨架的适配器。这个突变体是一个点突变破坏特定的细胞骨架连锁，扰乱地形轴突作图的第一个例子。在Aim 1中，将对L1（Y1229H）敲入小鼠的视网膜神经节细胞轴突进行轴突示迹，以确定沿正后轴和中外侧轴的视网膜定位模式，从而深入了解L1锚定在细胞骨架上轴突生长和突触靶向中的作用。在目标2中，细胞和生化分析将确定L1与细胞骨架结合所控制的蛋白质相互作用，这是轴突靶向和突触接触形成所必需的。我们设计了特定的实验来分析l1 -锚蛋白结合对整合素依赖性细胞粘附的调节作用，以及对ephrin和Eph受体（A类和B类）的吸引或排斥轴突引导。L1神经粘附分子与锚蛋白和ephrin/Eph受体的相互作用是一个新的概念，将促进对调节神经元连接机制的分子理解。这项研究对于理解神经元连接的基本机制具有广泛意义，因为L1是在大脑中广泛表达的粘附受体家族的原型，它们可能通过不同的锚蛋白异构体介导突触连接。培养本科生2名，研究生2名，博士后1名。这笔赠款将增加妇女对研究的参与，加强多样性和少数民族代表性，因为所有受训者都是妇女。对整个社会的总体利益将包括提供新的知识，这将增加对神经元连接基本机制的理解。这一知识将对更大范围的神经再生和神经移植产生广泛的影响，并可能为改善动物和人类的生活和健康提供新的手段。