UCL Institute of Ophthalmology, London, UK.
Hum Mol Genet. 2011 Jan 1;20(1):16-27. doi: 10.1093/hmg/ddq428. Epub 2010 Oct 1.
Mitochondrial dysfunction is characteristic of many neurodegenerative diseases. The Parkinson's disease-associated ubiquitin-protein ligase, Parkin, is important in the elimination of damaged mitochondria by autophagy (mitophagy) in a multistep process. Here, we show that a Parkin RING domain mutant (C289G) fails to redistribute to damaged mitochondria and cannot induce mitophagy after treatment with the mitochondrial uncoupler carbonyl cyanide m-methylhydrazone, because of protein misfolding and aggregation. Parkin(C289G) aggregation and inclusion formation were suppressed by the neuronal DnaJ/Hsp40 chaperone HSJ1a(DNAJB2a). Importantly, HSJ1a and DNAJB6 also restored mitophagy by promoting the relocation of Parkin(C289G) and the autophagy marker LC3 to depolarized mitochondria. The rescue of Parkin activity and suppression of aggregation were J domain dependent for HSJ1a, suggesting the involvement of Hsp70 in these processes, but were not dependent on the HSJ1a ubiquitin interaction motif. HSJ1a expression did not enhance mitophagy mediated by wild-type Parkin. These data show the potential of molecular chaperones to mediate the functional recovery of Parkin misfolding mutants and to combat deficits associated with Parkin aggregation in Parkinson's disease.
线粒体功能障碍是许多神经退行性疾病的特征。帕金森病相关的泛素蛋白连接酶 Parkin 在自噬（线粒体自噬）中通过多步过程清除受损的线粒体中起着重要作用。在这里，我们表明 Parkin RING 结构域突变体（C289G）在与线粒体解偶联剂羰基氰化物 m-甲基腙（carbonyl cyanide m-methylhydrazone）处理后不能重新分布到受损的线粒体，也不能诱导线粒体自噬，因为其蛋白质错误折叠和聚集。神经元 DnaJ/Hsp40 伴侣 HSJ1a（DNAJB2a）抑制 Parkin(C289G)聚集和包涵体形成。重要的是，HSJ1a 和 DNAJB6 还通过促进 Parkin(C289G)和自噬标记 LC3 向去极化线粒体的重新定位来恢复线粒体自噬。HSJ1a 对 Parkin 活性的恢复和聚集的抑制依赖于 J 结构域，这表明 Hsp70 参与了这些过程，但不依赖于 HSJ1a 的泛素相互作用基序。HSJ1a 的表达并没有增强野生型 Parkin 介导的线粒体自噬。这些数据表明，分子伴侣具有介导 Parkin 错误折叠突变体功能恢复的潜力，并能对抗帕金森病中与 Parkin 聚集相关的缺陷。
