Proteostasis dysregulation and alpha-synuclein

蛋白质稳态失调和 α-突触核蛋白

• 批准号: 10620658
• 负责人: XIN QI
• 金额: $ 60.45万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10620658
• 关键词: Aging; Alzheimer' s Disease; Amyloid beta-Protein; Animal Model; Area; Attenuated; Behavioral; Binding; Biochemical; Bioenergetics; Biology; Brain; Brain region; Cell Culture Techniques; Cell Death; Cell Nucleus; Cell Survival; Cells; Cognitive; Communication; Complex; Corpus striatum structure; Cultured Cells; Defect; Defense Mechanisms; Dementia with Lewy Bodies; Disease; Event; Exposure to; Fiber; Genes; Genetic Transcription; Goals; Health; Howard Temin Award; Human; Impairment; Lewy Body Dementia; Link; Mediating; Medical; Messenger RNA; Mitochondria; Mitochondrial Matrix; Mitochondrial Proteins; Molecular; Molecular Chaperones; Monitor; Motor Activity; Mus; Nerve Degeneration; Neurodegenerative Disorders; Neuronal Injury; Neurons; Oxidative Stress Induction; Parkinson Disease; Pathogenesis; Pathologic; Patients; Peptide Hydrolases; Peptides; Play; Production; Proteins; Proteomics; Reactive Oxygen Species; Regulation; Research; Role; Signal Pathway; Signal Transduction; Stress; Substantia nigra structure; Testing; Therapeutic; Time; Toxic effect; Transgenic Mice; United States National Institutes of Health; Work; alpha synuclein; dopaminergic neuron; genetic manipulation; induced pluripotent stem cell; inhibitor; mouse model; mouse synuclein alpha; mutant; neuropathology; novel; overexpression; proteostasis; response; synucleinopathy; tau Proteins; therapy development

Accumulation of alpha-synuclein (αSyn) causes degeneration of dopaminergic (DA) and non-DA neurons in Parkinson’s disease (PD) and Dementia with Lewy Bodies (DLB). αSyn also contributes to the fibrilization of amyloid-β and tau, two key proteins in Alzheimer’s disease (AD), which suggests a key role for αSyn toxicity in neurodegeneration. Thus, it is important to elucidate downstream effects and the factors promoting the toxic conversion of αSyn, towards understanding the pathogenesis of and developing disease-modifying therapies for synucleinopathies. In PD and DLB, pathological αSyn proteins enrich in mitochondria of vulnerable brain regions, where to induce mitochondrial bioenergetic defects and production of reactive oxygen species. Despite evidence suggests that αSyn-mitochondrial interactions may play a causal role in PD and DLB, the field lacks a detailed understanding of the mechanisms by which αSyn abnormality and mitochondrial functional deficiency influence each other. To maintain normal mitochondrial health and function, cells employ a mitochondria-to-nucleus signaling pathway termed the mitochondrial unfolded protein response (UPRmt). The UPRmt monitors mitochondrial proteostasis through mitochondrial specific proteases and molecular chaperones, which facilitate folding and/or degradation of unfolded proteins within mitochondria. They also communicate with the nucleus by retrograde signaling to activate the expression of peptide-folding related proteins. The UPRmt is an important defense mechanism for maintaining the quality of proteins within the mitochondria under stress. Defects in UPRmt have been linked to aging and neurodegeneration. Our recent work showed, for the first time, that the protein level of ClpP, a mitochondrial matrix protease induced during UPRmt activation, was decreased in neurons expressing αSyn wildtype (WT) or A53T mutant, in brains of mice carrying A53T mutant, and in the Substantia Nigra of PD patients. The mRNA level of ClpP remained unchanged, suggesting a transcriptional independent effect. Preliminary study further found that the protein level of ClpP and not other mitochondrial proteases, decreased in the cortex of patients with DLB and mice expressing human Thy1-αSyn. These results suggest that a decrease in ClpP is a common event implicated in the pathogenesis of both PD and DLB. Whereas silencing ClpP in neurons increased a load of unfolded proteins in the mitochondria, reduced mitochondrial bioenergetic activity and increased cell death; overexpressing ClpP abolished αSyn-induced oxidative stress in cultured cells, and attenuated αSyn hyper-phosphorylation and behavioral abnormality in αSyn A53T mice. Notably, we found that αSyn bound to ClpP and suppressed ClpP peptidase activity, whereas genetic manipulation of ClpP influenced the assembly of non-toxic αSyn tetramers that resist aggregation. Thus, our pilot findings highlight a previously unidentified interdependence between pathological αSyn and mitochondrial protease ClpP, which results in a disturbance of mitochondrial proteostasis, leading to neuronal damage. Given that αSyn accumulation is a common pathological hallmark of both PD and DLB, the goal of this study is to determine the role of ClpP-mediated mitochondrial proteostasis in PD and DLB at both mechanistic and therapeutic level. Built on our study supported by the NIH bridge award R56 NS105632-1A1, we will test the central hypothesis that pathological αSyn disturbs mitochondrial proteostasis by suppressing ClpP and UPRmt, which impairs mitochondrial bioenergetic activity and promotes the toxic conversion of αSyn, leading to αSyn neuropathology. Our research team has the unique synergistic expertise in UPRmt, mitochondrial biology, and αSyn neuropathology required to impact this significant area of unmet medical need. Successful completion of the proposed study will not only contribute to the basic understanding of disease pathogenesis, but it will also aid in the development of treatments for PD and DLB and even other neurodegenerative diseases in which αSyn aggregation manifests.

α-突触核蛋白(α-Syn)的积聚导致帕金森病(PD)和路易体痴呆(DLBD)中多巴胺(DA)能神经元和非DA能神经元的变性。αSYN还有助于将 淀粉样蛋白-β和tau是阿尔茨海默病(AD)中的两个关键蛋白，这表明α-Syn毒性在阿尔茨海默病(AD)中起关键作用。 神经退行性变。因此，阐明下游效应和促进毒性的因素是很重要的。 α-SYN的转换，有助于了解联体核病的发病机制和开发疾病修饰疗法。在PD和DLB中，病理性αSyn蛋白丰富在脆弱脑区的线粒体中，从而导致线粒体生物能缺陷和活性氧的产生。尽管有证据表明α突触与线粒体的相互作用可能在帕金森病和DLB的发病中起作用，但该领域对α突触异常和线粒体功能缺陷相互影响的机制缺乏详细的了解。为了维持正常的线粒体健康和功能，细胞使用线粒体到细胞核的信号通路，称为线粒体未折叠蛋白反应(UPRmt)。UPRmt通过线粒体特定的蛋白水解酶和分子伴侣来监测线粒体的蛋白平衡，这些酶和分子伴侣促进线粒体内未折叠蛋白质的折叠和/或降解。它们还通过逆行信号与细胞核进行交流，激活与肽折叠相关的蛋白的表达。UPRmt是在应激状态下维持线粒体内蛋白质质量的重要防御机制。UPRmt的缺陷被认为与衰老和神经退化有关。我们最近的工作首次表明，在表达αSyn野生型(WT)或A53T突变体的神经元中，在携带A53T突变体的小鼠脑中，在PD患者的黑质中，在UPRmt激活过程中诱导的一种线粒体基质蛋白酶ClpP的蛋白水平降低。ClpP的mRNA水平保持不变，提示存在转录独立效应。初步研究进一步发现，表达人Thy1-αSyn的患者和小鼠的大脑皮质中ClpP的蛋白水平降低，而不是其他线粒体蛋白水解酶的水平降低。这些结果表明，ClpP的降低是PD和DLB发病机制中的一个常见事件。虽然沉默神经元中的ClpP会增加线粒体中未折叠的蛋白质的负载， 降低线粒体生物能活性和增加细胞死亡；过表达ClpP可消除αSyn诱导的培养细胞的氧化应激，并减轻αSyn过度磷酸化和αSyn A53T小鼠的行为异常。值得注意的是，我们发现αSyn与ClpP结合并抑制ClpP多肽酶活性，而ClpP的基因操作影响了无毒的αSyn四聚体的组装，这些四聚体抵抗聚集。因此，我们的初步发现突显了病理性αSyn和线粒体蛋白水解酶ClpP之间以前未知的相互依赖关系，这会导致线粒体蛋白平衡紊乱，导致神经元损伤。鉴于α-Syn堆积是PD和DLB共同的病理特征，本研究的目的是从机制和治疗水平上确定ClpP介导的线粒体蛋白平衡在PD和DLB中的作用。在美国国立卫生研究院桥梁奖R56NS105632-1A1的支持下，我们将检验这一中心假设，即病理性αSYN通过抑制ClpP和UPRmt来干扰线粒体蛋白平衡，从而损害线粒体的生物能量活动，促进αSYN的毒性转化，导致αSyn神经病理。我们的研究团队在UPRMT、线粒体生物学和αSyn神经病理学方面拥有独特的协同专业知识，以影响这一未得到满足的医疗需求的重要领域。这项研究的成功完成不仅有助于对疾病发病机制的基本了解，还将有助于PD和DLB甚至其他以αSyn聚集为表现的神经退行性疾病的治疗方法的开发。