Defining TMEM184b-Controlled Pathways in Nerve Terminal Maintenance and Axon Degeneration

我们工作的总体目标是了解神经末梢和轴突是如何在整个过程中维持的 他们的生活和他们如何应对伤害。在周围神经系统（PNS）中，长的初级运动和感觉神经系统（LSM）是一种神经系统。 轴突及其末端易受多种促变性损伤的影响，包括代谢应激 在糖尿病期间，化疗药物的神经毒性，创伤性损伤和遗传性疾病， 腓骨肌萎缩侧索硬化症（ALS）。在这些疾病中，终末和轴突通常 首先受到影响的结构，它们的退化先于细胞体死亡。通过绘制出细胞， 遗传和生物化学景观的早期事件的神经终端和轴突变性，我们可能 确定延缓或预防神经退行性疾病中这种退化的方法。 我们主要研究TMEM 184 b的轴突和突触功能，TMEM 184 b是一个新发现的7-通道突触蛋白。 PNS中的跨膜蛋白。小鼠中TMEM 184 b的缺失导致两个运动神经系统中的进行性营养不良。 和感觉神经末梢，也会导致感觉运动缺陷。除了这些神经末梢 表型，果蝇或小鼠中TMEM 184 b的减少导致损伤后轴突完整性延长， 表明TMEM 184 b在轴突变性级联中是活性的。自噬体的积累， 在突变组织中可以看到溶酶体，即负责蛋白质和细胞器降解的区室。基于 基于这些数据，我们假设TMEM 184 b调节自噬的一个步骤。因为众所周知，自噬 促进轴突退化，也改变突触结构，这一假设将解释轴突和 TMEM 184 b突变小鼠的突触表型。 使用小鼠和果蝇系统，我们将结合分子和 遗传分析、电生理学、细胞生物学和行为学。在目标1中，我们将确定 通过研究神经肌肉突触，在缺乏TMEM 184 b的果蝇和小鼠中观察到感觉运动缺陷。 传递和感觉转导，分子表征终末营养不良，并评估 外周神经轴突运输。在目标2中，我们将探索由以下因素控制的细胞和分子途径： TMEM 184 b在培养的神经元和移植的组织中的表达，特别关注TMEM 184 b生物学特性的连接。 控制自噬的活性。在目标3中，我们将确定TMEM 184 b如何促进促退行性变 利用遗传上位性和生物化学，我们将研究TMEM 184 b的作用是否与神经元的损伤有关。 轴突变性在中枢神经系统中是保守的。 总之，我们的研究将描述一种新的神经元自噬控制机制， 早期神经退行性疾病这项工作将有助于发现新的战略，以阻止 神经退行性疾病中的神经末梢和轴突变性。

The overall objective of our work is to understand how nerve terminals and axons are maintained throughout life and how they respond to injury. In the peripheral nervous system (PNS), long primary motor and sensory axons and their terminals are susceptible to a wide variety of pro-degenerative insults, including metabolic stress during diabetes, neurotoxicities of chemotherapy drugs, traumatic injuries, and genetic disorders including Charcot-Marie-Tooth and Amyotrophic Lateral Sclerosis (ALS). In these disorders, terminals and axons are often the first affected structures, and their degeneration precedes cell body death. By mapping out the cellular, genetic, and biochemical landscape of the early events of nerve terminal and axon degeneration, we might identify ways to delay or prevent this degeneration in neurodegenerative disorders. We are focused on the axonal and synaptic functions of TMEM184b, a newly discovered 7-pass transmembrane protein, in the PNS. Loss of TMEM184b in mice causes progressive dystrophies in both motor and sensory nerve terminals, and also causes sensorimotor deficits. In addition to these nerve terminal phenotypes, reduction of TMEM184b in Drosophila or in mice leads to prolonged axon integrity after injury, suggesting TMEM184b is active in the axon degeneration cascade. Accumulations of autophagosomes and lysosomes, compartments responsible for protein and organelle degradation, are seen in mutant tissues. Based on these data, we hypothesize that TMEM184b regulates a step in autophagy. Because autophagy is known to promote axon degeneration and also alter synapse structure, this hypothesis would explain both the axon and synapse phenotypes of TMEM184b mutant mice. Using both mouse and Drosophila systems, we will test our hypothesis with a combination of molecular and genetic analysis, electrophysiology, cell biology, and behavior. In Aim 1, we will ascertain the root causes of the sensorimotor deficits seen in both flies and mice lacking TMEM184b by investigating neuromuscular synaptic transmission and sensory transduction, molecularly characterizing terminal dystrophies, and evaluating peripheral nerve axon transport. In Aim 2, we will probe the cellular and molecular pathways controlled by TMEM184b in cultured neurons and explanted tissues, with a particular focus on linking TMEM184b biological activity to the control of autophagy. In Aim 3, we will identify how TMEM184b contributes to pro-degenerative pathways in injured nerves using genetic epistasis and biochemistry, and we will ask whether TMEM184b's role in axon degeneration is conserved in the central nervous system. In summary, our research will describe a new mechanism of autophagy control in neurons that may underlie early stages of neurodegenerative diseases. This work will contribute to the discovery of new strategies to block nerve terminal and axon degeneration in neurodegenerative disorders.