Role of mitochondria in neurodegenerative diseases

线粒体在神经退行性疾病中的作用

• 批准号: 9563160
• 负责人: Richard James Youle
• 金额: $ 112.91万
• 依托单位: NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9563160
• 关键词: ATP phosphohydrolase; Alpha Cell; Animal Model; Autophagocytosis; Autophagosome; Cells; Cellular biology; Cytosol; Excision; Genes; Guanosine Triphosphate Phosphohydrolases; Impairment; Mammalian Cell; Mediating; Membrane; Mitochondria; Mitochondrial DNA; Mitochondrial Diseases; Mitochondrial Proteins; Modeling; Molecular; Mus; Mutate; Mutation; Neurodegenerative Disorders; Neurons; Organelles; Outer Mitochondrial Membrane; PINK1 gene; PTEN-induced putative kinase; PTGS1 gene; Parkinson Disease; Pathway interactions; Patients; Peptide Hydrolases; Phosphotransferases; Process; Quality Control; RNA interference screen; Recruitment Activity; Role; Signal Transduction; Testing; Therapeutic; Ubiquitin; Work; base; fly; gene product; in vivo; mitochondrial DNA mutation; multicatalytic endopeptidase complex; neuroprotection; parkin gene/protein; prevent; screening; selective expression; sensor; small molecule libraries; ubiquitin-protein ligase

We have explored the role of mitochondria in Parkinson's disease (PD). At least two gene products mutated in familial PD, PINK1 and Parkin, are now known to mediate autophagic removal of defective mitochondria suggesting that one cause of PD is an impairment of mitochondrial quality control. PINK1 is a kinase located on mitochondria whereas Parkin is an E3 ubiquitin ligase normally located in the cytosol. Upon mitochondrial damage Pink1 recruits cytosolic Parkin to mitochondria to mediate mitophagy revealing a cell biology pathway in mammalian cells where Pink1 works upstream of Parkin. We have found that PINK1 is rapidly turned over in cells. In healthy mitochondria PINK1 is constitutively imported into the inner membrane and degraded by the protease PARL, and maintained at very low levels. When mitochondria sustain damage PINK1 import and degradation is prevented allowing its accumulation on the outer mitochondrial membrane. Thus PINK1 acts as a sensor of mitochondria function. When PINK1 accumulates on the outer mitochondrial membrane of damaged organelles it recruits Parkin to mitochondria from the cytosol. Parkin recruitment requires PINK1 kinase activity but the substrate of PINK1 involved in this process remains unknown. Once on the mitochondria, Parkin ubiquitinates mitochondrial proteins including the GTPases Mfn1 and 2. The loss of ubiqutinated Mfn1 and 2 by proteosomal degradation prevents damaged mitochondria from fusing with healthy mitochondria thereby segregating them fordisposal. The ubiquitin chains Parkin forms on other mitochondrial proteins appear to signal the elimination of mitochondria by autophagy. We found that the proteosome and the AAA ATPase, p97/VCP, Optineurin or NDP52 and ATG5 are required for Parkin mediated mitophagy further indicating the importance of ubiquitin in Parkin mediated mitophagy. Corroborating this model we have found that in cybrid cells that contain a mixture of functional mitochondria with wild type mitochondrial DNA and dysfunctional mitochondria with a mutation in mitochondrial DNA in the COX1 gene, increasing Parkin expression selectively eliminates the damaged mitochondria and enriches for the propagation of wild type mitochondrial DNA. Based on these results we predict that stimulation of the PINK1/Parkin pathway may facilitate mitochondrial quality control and may be of potential therapeutic benefit for patients with mitochondrial diseases and certain forms of Parkinson's disease. An animal model that accumulates mitochondrial DNA mutations corroborates the model that Parkin mediates quality control and rescues neurons of damaged mitochondria. We have begun screening chemical libraries to identify agents that stimulate PINK1 expression and Parkin translocation. We have also completed RNAi screens to identify gene products participating in PINK1 recruitment of Parkin to mitochondria and Parkin stimulation of autophagosome engulfment of mitochondria.

我们探索了线粒体在帕金森病 (PD) 中的作用。目前已知至少有两种在家族性 PD 中发生突变的基因产物（PINK1 和 Parkin）可介导有缺陷的线粒体的自噬清除，这表明 PD 的原因之一是线粒体质量控制受损。 PINK1 是一种位于线粒体上的激酶，而 Parkin 是一种 E3 泛素连接酶，通常位于细胞质中。 线粒体损伤后，Pink1 将胞质 Parkin 募集至线粒体以介导线粒体自噬，揭示了哺乳动物细胞中 Pink1 在 Parkin 上游发挥作用的细胞生物学途径。我们发现 PINK1 在细胞中快速更新。 在健康的线粒体中，PINK1 被组成型导入内膜并被蛋白酶 PARL 降解，并维持在非常低的水平。 当线粒体受到损伤时，PINK1 的导入和降解被阻止，从而使其积聚在线粒体外膜上。 因此 PINK1 充当线粒体功能的传感器。当 PINK1 积聚在受损细胞器的线粒体外膜上时，它会将 Parkin 从细胞质中招募到线粒体。 Parkin 募集需要 PINK1 激酶活性，但参与此过程的 PINK1 底物仍然未知。一旦进入线粒体，Parkin 就会泛素化线粒体蛋白，包括 GTPases Mfn1 和 2。由于蛋白体降解而导致泛素化的 Mfn1 和 2 丢失，可防止受损线粒体与健康线粒体融合，从而将它们分离以供处理。 Parkin 在其他线粒体蛋白上形成的泛素链似乎发出自噬消除线粒体的信号。我们发现蛋白体和 AAA ATP 酶、p97/VCP、Optineurin 或 NDP52 和 ATG5 是 Parkin 介导的线粒体自噬所必需的，进一步表明泛素在 Parkin 介导的线粒体自噬中的重要性。 证实了这个模型，我们发现，在含有野生型线粒体DNA的功能性线粒体和COX1基因中线粒体DNA发生突变的功能障碍线粒体的混合细胞中，增加Parkin表达选择性地消除受损的线粒体并丰富野生型线粒体DNA的繁殖。 基于这些结果，我们预测刺激 PINK1/Parkin 通路可能有助于线粒体质量控制，并且可能对患有线粒体疾病和某些形式的帕金森病的患者具有潜在的治疗益处。 积累线粒体 DNA 突变的动物模型证实了 Parkin 介导质量控制并拯救受损线粒体神经元的模型。我们已经开始筛选化学文库，以确定刺激 PINK1 表达和 Parkin 易位的药物。 我们还完成了 RNAi 筛选，以鉴定参与 PINK1 将 Parkin 招募到线粒体以及 Parkin 刺激线粒体自噬体吞噬的基因产物。