Optineurin is an autophagy receptor for damaged mitochondria in parkin-mediated mitophagy that is disrupted by an ALS-linked mutation
Optineurin is an autophagy receptor for damaged mitochondria in parkin-mediated mitophagy that is disrupted by an ALS-linked mutation
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DOI：
10.1073/pnas.1405752111
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发表时间：
2014-10-21
影响因子：
11.1
通讯作者：
Holzbaur, Erika L. F.
中科院分区：
文献类型：
--
作者：
Wong, Yvette C.;Holzbaur, Erika L. F.
线粒体自噬是一种细胞质量控制途径，其中E3泛素连接酶帕金靶向受损的线粒体，使其被自噬体降解。我们研究了optinineurin在线粒体自噬中的作用，因为optinineurin的突变是肌萎缩性侧索硬化症（ALS）和青光眼的病因，这些疾病与线粒体功能障碍有关。利用活细胞成像，我们证明了optinurin在去极化或活性氧损伤的线粒体中的帕金森依赖性募集。泛素化线粒体外膜蛋白需要Parkin的E3泛素连接酶活性，从而允许optinurin通过其泛素结合域稳定地与泛素化的线粒体结合；在缺乏帕金的情况下，优神经蛋白会短暂地定位于受损的线粒体尖端。在opopineurin募集后，omegasome蛋白双FYVE-containing protein 1 （DFCP1）短暂地定位于受损的线粒体，初始化自噬体的形成和微管相关蛋白轻链3 （LC3）的募集。optinurin随后通过其LC3相互作用区（LIR）结构域诱导受损线粒体周围的自噬体形成。内源性opopineurin的耗竭抑制LC3向线粒体的募集并抑制线粒体降解。这些缺陷可以通过sirna抗性野生型optinurin的表达来修复，但不能通过泛素结合域（E478G）的als相关突变或LIR结构域突变来修复。Optineurin和p62/SQSTM1被独立募集到受损线粒体的分离结构域，p62不需要Optineurin或LC3募集到受损线粒体。因此，我们的研究确定了opopineurin作为自噬受体在帕金森介导的有丝分裂中发挥重要作用，并表明单一途径的缺陷可导致具有不同病理的神经退行性疾病。
Mitophagy is a cellular quality control pathway in which the E3 ubiquitin ligase parkin targets damaged mitochondria for degradation by autophagosomes. We examined the role of optineurin in mitophagy, as mutations in optineurin are causative for amyotrophic lateral sclerosis (ALS) and glaucoma, diseases in which mitochondrial dysfunction has been implicated. Using live cell imaging, we demonstrate the parkin-dependent recruitment of optineurin to mitochondria damaged by depolarization or reactive oxygen species. Parkin's E3 ubiquitin ligase activity is required to ubiquitinate outer mitochondrial membrane proteins, allowing optineurin to stably associate with ubiquitinated mitochondria via its ubiquitin binding domain; in the absence of parkin, optineurin transiently localizes to damaged mitochondrial tips. Following optineurin recruitment, the omegasome protein double FYVE-containing protein 1 (DFCP1) transiently localizes to damaged mitochondria to initialize autophagosome formation and the recruitment of microtubule-associated protein light chain 3 (LC3). Optineurin then induces autophagosome formation around damaged mitochondria via its LC3 interaction region (LIR) domain. Depletion of endogenous optineurin inhibits LC3 recruitment to mitochondria and inhibits mitochondrial degradation. These defects are rescued by expression of siRNA-resistant wild-type optineurin, but not by an ALS-associated mutant in the ubiquitin binding domain (E478G), or by optineurin with a mutation in the LIR domain. Optineurin and p62/SQSTM1 are independently recruited to separate domains on damaged mitochondria, and p62 is not required for the recruitment of either optineurin or LC3 to damaged mitochondria. Thus, our study establishes an important role for optineurin as an autophagy receptor in parkin-mediated mitophagy and demonstrates that defects in a single pathway can lead to neurodegenerative diseases with distinct pathologies.