Mechanisms of Target-Specific Axon Regeneration

项目摘要 神经损伤是一种常见的痛苦，导致感觉和/或运动缺陷。恢复涉及到 神经纤维内受损轴突必须重新延伸到适当目标的再生过程 组织，在一个被称为目标特异性再生的过程中。这一过程在人类身上常常失败， 有慢性健康问题改善临床结果需要更好地了解靶向特异性 再生是有规律的。我们知道神经支持支架的组成部分可以引导轴突重新延伸 沿着简单的路径。然而，当轴突到达神经分支点时，它们需要更具体的引导 机制来区分多个路径并选择正确的路径。我们对 什么样的环境线索引导这些决定，以及它们如何被再生的轴突适当地解释。 这个建议的目的是确定调节轴突靶向的细胞和分子机制 促进特定目标再生的决定。 我已经建立了斑马鱼迷走神经作为模型，以阐明靶特异性轴突的机制， 再生再生迷走神经轴突在五个神经分支之间选择，以稳健地重新支配正确的神经。 靶组织，尽管它们如何做到这一点尚不清楚。我假设两个非互斥的机制 调节靶特异性再生：1）化学感觉，其中再生轴突可以空间解释 环境中指导其生长的模式化化学引导线索; 2）束颤，其中 再生轴突可以识别未受损的轴突，这些轴突支配它的预定目标，并将它们用作 用于定向生长的基质。这项提案的三个目标将全面确定生长的轴突如何 在靶特异性再生期间，在细胞生物学和分子水平上与其环境相互作用。在 目的1，我将联合收割机结合一种新的单细胞嵌合体再生试验与活体成像和遗传学， 药理学操作，以建立一个概念性的理解，如何在体内轴突环境 互动指导目标选择决策。在目标2中，我将联合收割机结合一种新的方法来标记和分离活神经元 基于它们的神经支配目标，用体内和体外技术精确地测量每个神经元的轴突 五个神经支配目标组与环境中的其它轴突和化学信号相互作用。在Aim中 3、将联合收割机神经支配靶点特异性神经元分离与RNAseq和突变体分析相结合， 鉴定在五个神经支配靶组中的每一个中调节靶选择的分子。本研究 这将极大地增强我们对轴突如何重新支配其靶组织的基本理解， 再生，并提供了一个重要的知识基础，以开发改进的治疗神经损伤。

Project Summary Nerve damage is a common affliction that causes sensory and/or motor deficits. Recovery involves a regenerative process in which damaged axons within a nerve fiber must re-extend to the appropriate target tissues, in a process known as target-specific regeneration. This process often fails in humans, leaving patients with chronic health problems. Improving clinical outcomes requires a better understanding of how target-specific regeneration is regulated. We know that components of the nerve support scaffold can guide axon re-extension along simple paths. However, when axons reach nerve branch points, they require more specific guidance mechanisms to differentiate between multiple paths and select the correct one. We have little understanding of what environmental cues guide these decisions, and how they are appropriately interpreted by regrowing axons. The objective of this proposal is to identify cellular and molecular mechanisms that regulate axon targeting decisions to promote target-specific regeneration. I have established the zebrafish vagus nerve as a model to elucidate mechanisms of target-specific axon regeneration. Regenerating vagus axons select between five nerve branches to robustly re-innervate the correct target tissue, although how they do so is not known. I hypothesize that two non-mutually-exclusive mechanisms regulate target-specific regeneration: 1) chemosensation, in which a regenerating axon can interpret spatially patterned chemical guidance cues in the environment that direct its growth; 2) fasciculation, in which a regenerating axon can recognize undamaged axons that are innervating its intended target and use them as a substrate for directed growth. The three aims of this proposal will comprehensively identify how growing axons interact with their environment at the cell biological and molecular levels during target-specific regeneration. In Aim 1, I will combine a novel single-cell chimera regeneration assay with live imaging and genetic and pharmacological manipulations to establish a conceptual understanding of how in vivo axon-environment interactions guide targeting decisions. In Aim 2, I will combine a novel method to label and isolate live neurons based on their innervation target with in vivo and in vitro techniques to precisely measure how axons of each of the five innervation target groups interact with other axons, and with chemical signals, in the environment. In Aim 3, I will combine innervation target-specific neuron isolation with RNAseq and mutant analysis for unbiased identification of molecules that regulate target selection in each of the five innervation target groups. This study will greatly enhance our fundamental understanding of how axons reinnervate their target tissues during regeneration, and provide an important knowledge base to develop improved treatments for nerve damage.