Role of UCH-L1 Oxidative Modification in Parkinson's Disease Pathogenesis

UCH-L1 氧化修饰在帕金森病发病机制中的作用

• 批准号: 7807231
• 负责人: JEANNE Elizabeth MCKEON
• 金额: $ 4.14万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7807231
• 关键词: Affect; Alanine; Aspartate; Autophagocytosis; Autopsy; Biochemical; Biological Assay; Bradykinesia; Brain; Brain region; Cell Death; Cell Survival; Cell physiology; Cells; Cysteine; Degradation Pathway; Deposition; Deubiquitinating Enzyme; Deubiquitination; Development; Disease; Dopaminergic Cell; Exposure to; Family; Functional disorder; Generations; Human; Hydrolase; Impairment; In Vitro; Individual; Isoleucine; Lewy Bodies; Link; Lysine; Mass Spectrum Analysis; Mediating; Methionine; Modification; Molecular Chaperones; Motor; Mus; Mutate; Mutation; Nerve Degeneration; Neurodegenerative Disorders; Neurons; Oxidative Stress; Parkinson Disease; Pathogenesis; Pathway interactions; Patients; Polyacrylamide Gel Electrophoresis; Predisposition; Property; Proteins; Reactive Oxygen Species; Reporting; Rest Tremor; Risk Factors; Role; Rotenone; Severities; Substantia nigra structure; System; Testing; Tissues; Toxic Environmental Substances; Toxicant exposure; Ubiquitin; Western Blotting; axonal degeneration; dinitrophenylhydrazine; disorder risk; immunocytochemistry; inhibition of autophagy; motor learning; multicatalytic endopeptidase complex; mutant; novel therapeutics; overexpression; oxidation; prevent; protein degradation; research study; small hairpin RNA; two-dimensional

DESCRIPTION (provided by applicant): Parkinson's disease (PD) is the most common neurodegenerative disorder affecting the motor system, and is characterized clinically by bradykinesia and resting tremor, and pathologically by dopaminergic neurodegeneration and intracellular Lewy body deposition. Ubiquitin carboxyl-terminal-hydrolase LI (UCH- L1) is an abundant neuronal deubiquitinating enzyme, and recently the I93M mutation of UCH-L1 was described in a family with autosomal dominant PD. UCH-L1 is implicated in both the ubiquitin proteasome system (UPS) and chaperone mediated autophagy (CMA) protein degradation pathways. PD-linked I93M mutant UCH-L1 demonstrates significantly reduced deubiquitinating activity and additionally, I93M mutant UCH-L1 overexpression is associated with dopaminergic neurodegeneration and inhibition of the CMA pathway. Mice lacking functional UCH-L1 display axonal degeneration, reduced free monomeric ubiquitin level, and motor and learning deficits. Decreased expression of UCH-L1 is observed in cortex of sporadic PD patients, as well as extensive modification by carbonylation and oxidation at methionine and cysteine residues. Together these observations suggest that UCH-L1 dysfunction is detrimental to neurons, and may contribute to PD pathogenesis. Exposure to environmental toxicants which are linked to increased reactive oxygen species (ROS) generation has been identified as a PD risk factor. The mechanism by which environmental toxicants contribute to PD pathogenesis remains unclear, but one possibility is that increased ROS induce oxidative modification of particular target proteins, such as UCH-L1, leading to pathological alteration of their cellular function. This proposal will test the hypothesis that environmental-toxicant induced oxidative stress causes oxidative modification of UCH-L1, thereby disrupting the role of UCH-L1 in the UPS and CMA degradation pathways, which leads to toxic protein accumulation and dopaminergic cell death. The specific aims are to 1) determine the severity of UCH-L1 oxidative modification in the predominantly affected brain region in PD, the substantia nigra, and to evaluate UCH-L1 as a target of oxidative modification caused by environmental toxicant exposures; 2) characterize the effects of oxidative modification of UCH-L1 on enzymatic activity and interactions with CMA machinery; and 3) determine the effects of UCH-L1 oxidative modification on the UPS and CMA protein degradation pathways and cell viability. Understanding the role of UCH-L1 oxidative modification and subsequent alterations of its function on protein degradation and cell viability will contribute to the understanding of PD pathogenesis and to the development of novel therapeutics or treatments for this disease.

描述（由申请人提供）：帕金森病（PD）是影响运动系统的最常见的神经退行性疾病，临床特征为运动迟缓和静止性震颤，病理特征为多巴胺能神经变性和细胞内路易体沉积。泛素羧基末端水解酶LI（UCH-L1）是一种丰富的神经元去泛素化酶，最近在一个常染色体显性遗传PD家系中发现了UCH-L1的I93M突变。UCH-L1参与泛素蛋白酶体系统（UPS）和伴侣介导的自噬（CMA）蛋白降解途径。PD连锁的I93M突变型UCH-L1显示出去泛素化活性显著降低，此外，I93M突变型UCH-L1过表达与多巴胺能神经变性和CMA通路抑制相关。缺乏功能性UCH-L1的小鼠表现出轴突变性、游离单体泛素水平降低以及运动和学习缺陷。在散发性PD患者的皮质中观察到UCH-L1的表达降低，以及通过甲硫氨酸和半胱氨酸残基的羰基化和氧化进行的广泛修饰。总之，这些观察结果表明，UCH-L1功能障碍是有害的神经元，并可能有助于PD的发病机制。暴露于与活性氧（ROS）生成增加相关的环境毒物已被确定为PD风险因素。环境毒物促进PD发病机制的机制尚不清楚，但一种可能性是增加的ROS诱导特定靶蛋白（如UCH-L1）的氧化修饰，导致其细胞功能的病理学改变。该提案将检验以下假设：环境毒物诱导的氧化应激导致UCH-L1的氧化修饰，从而破坏UCH-L1在UPS和CMA降解途径中的作用，这导致毒性蛋白质积累和多巴胺能细胞死亡。具体目的是1）确定UCH-L1在PD中主要受影响的脑区域（黑质）中氧化修饰的严重程度，并评估UCH-L1作为环境毒物暴露引起的氧化修饰的靶点; 2）表征UCH-L1的氧化修饰对酶活性和与CMA机制的相互作用的影响;和3）确定UCH-L1氧化修饰对UPS和CMA蛋白降解途径和细胞活力的影响。了解UCH-L1氧化修饰的作用及其对蛋白质降解和细胞活力功能的后续改变将有助于了解PD发病机制和开发这种疾病的新疗法或治疗方法。