Regulation of protein targeting in axon guidance and neuronal morphogenesis

 描述(由申请人提供)：神经元形态和神经回路的正确发展，以及神经元的维护，需要严格控制蛋白质的亚细胞定位，如轴突引导线索受体。蛋白质通过复杂的膜运输和轴突运输系统定位于特定的细胞位置。神经元由于其高度极化和复杂的结构，尤其依赖于高保真的蛋白质运输。贩运和运输方面的缺陷是多种人类发育和神经退行性疾病的基础，包括阿尔茨海默病、夏科特-玛丽-图斯和尼曼-皮克病。尽管它们很重要，但调控神经元运输过程的机制却知之甚少，部分原因是缺乏体内模型来研究轴突运输的机制和机制。该领域面临的一个主要挑战和该项目的长期目标是了解神经元在自然环境中发育时控制轴突运输和蛋白质定位的机制，在自然环境中，神经元必须整合多种细胞外信号。我们建立了一个模型，在该模型中，我们可以成像完整斑马鱼胚胎中神经元货物运输、蛋白质定位和微管行为的动力学。脊椎动物的感觉神经元延伸不同的中枢和外周轴突，形成感觉回路。我们发现，这些轴突对轴突引导线索表现出不同的反应。此外，我们还发现了内体转运和动蛋白适配器Calsyntenin-1(Clstn-1)在感觉神经轴突的差异引导中的作用。在目标1中，我们建议确定Calsyntenins如何调节内体到不同轴突间隔的运输路线。在目标2中，我们将研究调节神经营养素-3和Semaphorin 3d受体特异性定位的机制。我们将测试Calsyntenins和另一类激动素适配器，Collip sin Response Mediator Proteins(CRMPs)功能靶向特定轴突间隔的受体的假设。在目标3中，我们将确定Clstn-1和CRMP如何组织微管的极性和动力学，这是准确运输和轴突生长所必需的过程。我们独特的模型允许我们将轴突运输、引导受体定位和微管组织的分子事件与特定的轴突引导决定联系起来，这些决定发生在它们自然发生的时间和地点。阐明调节感觉神经轴突生长、引导和蛋白质运输的分子信号对 了解神经退行性疾病、神经病理性疼痛障碍以及轴突损伤后可能发生再生的条件。我们的实验将揭示这种机制，从而可能有助于确定疾病治疗的分子靶点。

 DESCRIPTION (provided by applicant): Proper development of neuronal morphology and neural circuits, as well as neuronal maintenance, requires tightly controlled subcellular localization of proteins such as axon guidance cue receptors. Proteins are targeted to specific cell locations by elaborate membrane trafficking and axonal transport systems. Neurons are particularly dependent on high fidelity protein trafficking because of their highly polarized and complex structure. Defects in trafficking and transport underlie multiple human developmental and neurodegenerative diseases, including Alzheimer's disease, Charcot-Marie-Tooth, and Niemann Pick disease. Despite their importance, the mechanisms regulating trafficking processes in neurons are poorly understood, in part due to a paucity of in vivo models in which the machinery and mechanisms of axon transport can be studied. A major challenge to the field and the long term goal of this project is to understand the mechanisms controlling axonal transport and protein localization as neurons develop in their natural environment, where they must integrate multiple extracellular cues. We established a model in which we can image dynamics of neuronal cargo transport, protein localization, and microtubule behavior in the intact zebrafish embryo. Vertebrate sensory neurons extend distinct central and peripheral axons to form the sensory circuit. We found that these axons show distinct responses to axon guidance cues. Moreover, we discovered roles for endosomal trafficking and the kinesin adaptor Calsyntenin-1 (Clstn-1) in differential guidance of sensory axons. In Aim 1 we propose to determine how calsyntenins regulate endosome transport routes to different axon compartments. In Aim 2 we will investigate mechanisms regulating specific localization of receptors for Neurotrophin-3 and Semaphorin3d. We will test the hypothesis that Calsyntenins and another class of kinesin adaptors, the Collapsin response mediator proteins (CRMPs) function to target receptors to specific axon compartments. In Aim 3 we will determine how Clstn-1 and CRMPs organize microtubule polarity and dynamics, processes essential for accurate trafficking and axon growth. Our unique model allows us to connect the molecular events of axonal transport, guidance receptor localization and microtubule organization to specific axon guidance decisions at the time and place they naturally occur. Elucidation of the molecular signals regulating sensory axon growth, guidance, and protein trafficking is critical for understanding neurodegenerative disorders, neuropathic pain disorders and the conditions under which regeneration after axon injury can occur. Our experiments will uncover such mechanisms and thus may help to identify molecular targets for disease treatment.