Dissecting the molecular pathways controlling axon degeneration after injury

描述（由申请人提供）：损伤后外周感觉轴突的变性是一个由特定的内在和外在途径调节的主动过程。我有兴趣了解外周轴突变性和再生的机制，这具有重要的临床意义，但很难在人类患者中进行细胞或分子分辨率的研究。我们已经建立了一个模型来研究活体斑马鱼胚胎的感觉轴突变性。斑马鱼是研究神经元发育的极好模型，因为它们在外部受精，发育迅速，并且在受精后的几天内保持透明，允许在活体中真实的时间内观察神经元重塑的整个过程。 在外周感觉轴突损伤后，不再与细胞体连接的轴突的远端部分通过称为沃勒变性的过程迅速分解。碎裂和碎片清除的迅速性质意味着遗传途径或外部影响是引发这种积极反应的原因。我们精确的激光轴突切断技术与延时共聚焦成像相结合，可以对轴突变性过程进行详细的定量分析。通过了解和改变退化的机制，有可能提高受损轴突再生和占据其先前领地的能力。或者，完全防止变性的发生可以使受损的轴突得到修复，从而恢复其功能。任何新发现的影响变性的分子途径都可能激发周围神经损伤或急性损伤患者的治疗。这项建议主要集中在三叉神经感觉神经元，触觉感觉神经元，支配头部的外周感觉轴突的变性。 具体目标1：确定在不同环境中控制轴突变性的内在途径具体目标2：鉴定在不同环境中负责清除轴突碎片的吞噬细胞

DESCRIPTION (provided by applicant): The degeneration of peripheral sensory axons after injury is an active process regulated by specific intrinsic and extrinsic pathways. I am interested in understanding the mechanisms of peripheral axon degeneration and regeneration, which have important clinical implications but are difficult to study with cellular or molecular resolution in human patients. We have developed a model to study sensory axon degeneration in live zebrafish embryos. Zebrafish are an excellent model for studying neuronal development since they are fertilized externally, develop quickly, and remain transparent for several days post-fertilization, allowing the entire process of neuronal remodeling to be observed in real time in a live organism. Following injury to peripheral sensory axons, the distal portion of the axon that is no longer connected to the cell body quickly breaks down by a process called Wallerian degeneration. The rapid nature of the fragmentation and debris clearance implies that genetic pathways or external influences are responsible for instigating this active response. Our precise laser axotomy technique paired with time-lapse confocal imaging allows for detailed, quantitative analysis of the process of axon degeneration. By understanding and altering the mechanisms of degeneration, it may be possible to improve the ability of an injured axon to regenerate and occupy its previous territory. Alternatively, preventing degeneration from occurring altogether may allow an injured axon to be repaired, thus restoring its function. Any new molecular pathways discovered that affect degeneration could potentially inspire therapies for patients with peripheral nerve damage or acute injury. This proposal focuses primarily on the degeneration of peripheral sensory axons of trigeminal sensory neurons, touch-sensing neurons that innervate the head. Specific Aim 1: To determine the intrinsic pathways controlling axon degeneration in different contexts Specific Aim 2: To identify the phagocytes responsible for removing axonal debris in different environments