Proteostasis dysregulation and alpha-synuclein

蛋白质稳态失调和 α-突触核蛋白

• 批准号: 10400854
• 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 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10400854
• 关键词: Aging; Alzheimer' s Disease; Amyloid beta-Protein; Animal Model; Area; Attenuated; Behavioral; Biochemical; Bioenergetics; Biology; Brain; Brain region; Cell Culture Techniques; Cell Death; Cell Nucleus; Cell Survival; Cells; Cognitive; 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; Parkinson Disease; Parkinson' s Dementia; 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; 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（αSyn）的积累导致帕金森病（PD）和路易体痴呆（DLB）中多巴胺（DA）和非DA神经元的变性。αSyn也有助于纤维化， 淀粉样蛋白-β和tau是阿尔茨海默病（AD）的两种关键蛋白，这表明αSyn毒性在阿尔茨海默病中起关键作用。 神经变性因此，重要的是要阐明下游效应和促进毒性的因素， αSyn的转化，以了解突触核蛋白病的发病机制和开发疾病修饰疗法。在PD和DLB中，病理性αSyn蛋白富集在脆弱脑区的线粒体中，在那里诱导线粒体生物能量缺陷和活性氧的产生。尽管有证据表明α Syn-线粒体相互作用可能在PD和DLB中发挥因果作用，但该领域缺乏对αSyn异常和线粒体功能缺陷相互影响的机制的详细了解。为了维持正常的线粒体健康和功能，细胞采用称为线粒体未折叠蛋白反应（UPRmt）的线粒体至细胞核信号通路。UPRmt通过线粒体特异性蛋白酶和分子伴侣监测线粒体蛋白质稳态，其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传导与细胞核通信，以激活肽折叠相关蛋白的表达。UPRmt是在应激下维持线粒体内蛋白质质量的重要防御机制。UPRmt的缺陷与衰老和神经变性有关。我们最近的工作首次表明，在表达αSyn野生型（WT）或A53 T突变体的神经元中，在携带A53 T突变体的小鼠脑中，以及在PD患者的黑质中，在UPRmt激活期间诱导的线粒体基质蛋白酶ClpP的蛋白水平降低。ClpP的mRNA水平保持不变，表明转录独立的效果。初步研究进一步发现，在DLB患者和表达人Thy 1-αSyn的小鼠的皮质中，ClpP而不是其他线粒体蛋白酶的蛋白水平降低。这些结果表明，ClpP的降低是涉及PD和DLB的发病机制的常见事件。虽然神经元中ClpP的沉默增加了线粒体中未折叠蛋白的负载， 过表达ClpP可消除α Syn诱导的细胞氧化应激，并减轻αSyn A53 T小鼠的αSyn过度磷酸化和行为异常。值得注意的是，我们发现αSyn与ClpP结合并抑制ClpP肽酶活性，而ClpP的遗传操作影响了抵抗聚集的无毒αSyn四聚体的组装。因此，我们的初步研究结果强调了病理性αSyn和线粒体蛋白酶ClpP之间先前未识别的相互依赖性，这导致线粒体蛋白质稳态的紊乱，从而导致神经元损伤。鉴于αSyn蓄积是PD和DLB的共同病理学标志，本研究的目标是在机制和治疗水平确定ClpP介导的线粒体蛋白质稳态在PD和DLB中的作用。基于我们由NIH桥梁奖R56 NS 105632 - 1A 1支持的研究，我们将检验中心假设，即病理性αSyn通过抑制ClpP和UPRmt来干扰线粒体蛋白质稳态，这会损害线粒体生物能量活性并促进αSyn的毒性转化，导致αSyn神经病理学。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，可以影响这一未满足医疗需求的重要领域。成功完成拟议的研究不仅有助于对疾病发病机制的基本了解，而且还有助于开发PD和DLB甚至其他表现出αSyn聚集的神经退行性疾病的治疗方法。