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) 的积累会导致帕金森病 (PD) 和路易体痴呆 (DLB) 中的多巴胺能 (DA) 和非 DA 神经元变性。 αSyn 还有助于纤维化 β 淀粉样蛋白和 tau 蛋白是阿尔茨海默病 (AD) 的两种关键蛋白，这表明 αSyn 毒性在 神经变性。因此，阐明下游效应和促进毒性的因素非常重要。 αSyn 的转化，以了解突触核蛋白病的发病机制并开发疾病修饰疗法。在 PD 和 DLB 中，病理性 αSyn 蛋白在脆弱大脑区域的线粒体中富集，从而诱导线粒体生物能缺陷和活性氧的产生。尽管有证据表明 αSyn-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，细胞采用线粒体到细胞核的信号传导途径，称为线粒体未折叠蛋白反应（UPRmt）。 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，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通讯，以激活肽折叠相关蛋白的表达。 UPRmt 是在压力下维持线粒体内蛋白质质量的重要防御机制。 UPRmt 缺陷与衰老和神经退行性疾病有关。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、携带 A53T 突变体的小鼠大脑以及 PD 患者的黑质中，ClpP（一种在 UPRmt 激活过程中诱导的线粒体基质蛋白酶）的蛋白水平降低。 ClpP 的 mRNA 水平保持不变，表明转录独立效应。初步研究进一步发现，DLB 患者和表达人 Thy1-αSyn 的小鼠皮质中 ClpP 的蛋白水平下降，而不是其他线粒体蛋白酶。这些结果表明 ClpP 降低是 PD 和 DLB 发病机制中涉及的常见事件。然而沉默神经元中的 ClpP 会增加线粒体中未折叠蛋白的负载， 线粒体生物能活性降低，细胞死亡增加；过表达 ClpP 消除了培养细胞中 αSyn 诱导的氧化应激，并减弱了 αSyn A53T 小鼠中的 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，这会导致线粒体蛋白质稳态紊乱，从而导致神经元损伤。鉴于 αSyn 积累是 PD 和 DLB 的共同病理标志，本研究的目标是在机制和治疗水平上确​​定 ClpP 介导的线粒体蛋白质稳态在 PD 和 DLB 中的作用。基于我们获得 NIH 桥梁奖 R56 NS105632-1A1 支持的研究，我们将测试以下核心假设：病理性 αSyn 通过抑制 ClpP 和 UPRmt 扰乱线粒体蛋白质稳态，从而损害线粒体生物能活性并促进 αSyn 的毒性转化，从而导致 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的医疗需求的重要领域。成功完成拟议研究不仅有助于对疾病发病机制的基本了解，而且还将有助于开发 PD 和 DLB 甚至其他出现 αSyn 聚集的神经退行性疾病的治疗方法。