Investigating the Activation Mechanism of SARM1 during Axon Degeneration

项目总结 损伤后，轴突开始死亡，其特征是轴突碎裂和解体。 髓鞘的一部分。这一过程通常被称为以奥古斯都·沃勒的名字命名的沃勒式退化。沃勒式的 退行性变在形态上与沃勒退行性变相似，与早期的 许多神经退行性疾病，包括阿尔茨海默氏症、亨廷顿氏症和帕金森氏症。沃勒恩 长期以来，退化被认为是被动发生的，但随着积极预防或促进蛋白质的发现 退化否定了这一观点。其中一种蛋白质是Sarm1。Sarm1是一种NAD+水解酶，将NAD+分解为 烟酰胺、ADPR和环状ADPR；这些产物的产生最终导致轴突变性。 此外，Sarm1基因敲除延缓了沃勒样疾病动物模型的退化，包括 创伤性脑损伤和周围神经病变。鉴于Sarm1在沃勒样疾病中的关键作用， 这一建议的中心假设是抑制Sarm1将阻止轴突的病理生理学。 与神经退行性疾病相关的退行性疾病。然而，sarm1抑制剂的开发受到限制。 由于缺乏关于这种酶的调节、结构和机制的知识。因此，我们的目标是 这一建议的目的是在沃勒变性的背景下理解Sarm1的调控，这一目标将 通过追求以下具体目标来实现。目标1专注于识别调节Sarm1的蛋白质 活动。邻近标记也将用于识别与Sarm1相互作用的蛋白质。其影响 Sarm1相互作用蛋白对NAD+水解酶活性和Sarm1介导的轴突变性的影响 评估过了。这些实验将确定在轴突退化过程中调节Sarm1的分子间事件。 目标2将重点了解TIR-1的结构和功能，TIR-1是线虫Sarm1的同源基因。这里, 我们将解决TIR-1的结构，并对该酶的酶机制进行表征。这些研究将 补充了最近对Sarm1的结构和动力学研究，并将对分子内的 Sarm1/TIR-1的特性有助于其退变能力。对监管的调查 Sarm1，包括分子间和分子内，在神经退行性疾病的背景下是一个快速增长的领域。 因此，这项工作的完成将大大增强我们对基本分子的理解 控制轴突退化的机制。这些研究将深入了解Sarm1在轴突中的作用 变性，这将在神经退行性疾病的治疗发展中具有广泛的意义 疾病。

PROJECT SUMMARY After injury, axons begin to die via a process that is characterized by axonal fragmentation and disintegration of myelin sheath. This process is often termed Wallerian degeneration after Augustus Waller. Wallerian-like degeneration, which is morphologically similar to Wallerian degeneration, is associated with the early stages of many neurodegenerative diseases, including as Alzheimer’s, Huntington’s, and Parkinson’s Diseases. Wallerian degeneration was long thought to occur passively, but the discovery of proteins that actively prevent or promote degeneration negated this idea. One such protein is SARM1. SARM1 is a NAD+ hydrolase that cleaves NAD+ to nicotinamide, ADPR, and cyclic ADPR; generation of these products ultimately leads to axonal degeneration. Moreover, SARM1 knockout delays degeneration in animal models of Wallerian-like diseases, including traumatic brain injury and peripheral neuropathy. Given the critical role of SARM1 in Wallerian-like diseases, the central hypothesis of this proposal is that SARM1 inhibition would prevent the pathophysiology of axon degeneration associated with neurodegenerative diseases. However, development of SARM1 inhibitors is limited by the lack of knowledge surrounding the regulation, structure, and mechanism of this enzyme. As such, the goal of this proposal is to understand SARM1 regulation in the context of Wallerian degeneration, and this goal will be achieved by pursing the following Specific Aims. Aim 1 focuses on identifying proteins that regulate SARM1 activity. Proximity dependent labeling will also be used to identify proteins that interact with SARM1. The impact of SARM1 interacting proteins on NAD+ hydrolase activity and SARM1-mediated axon degeneration will also be assessed. These experiments will identify intermolecular events that regulate SARM1 during axon degeneration. Aim 2 will focus on understanding the structure and function of TIR-1, the C. elegans ortholog of SARM1. Here, we will solve the TIR-1 structure and characterize the enzymatic mechanism of this enzyme. These studies will complement recent structural and kinetic studies of SARM1 and will yield insights into the intramolecular characteristics of SARM1/TIR-1 that contribute to its degenerative capacity. Investigation into the regulation of SARM1, both inter- and intramolecularly, is a rapidly growing field in the context of neurodegenerative diseases. As such, completion of this work will significantly enhance our understanding of the fundamental molecular mechanisms that control axonal degeneration. These studies will yield insights into the role of SARM1 in axon degeneration, which will have broad implications in the development of therapeutics for neurodegenerative diseases.