Parkin功能丧失增强细胞自噬

Loss of Parkin Function Enhances Autophagy

Parkin(PARK2)基因的突变与家族性帕金森综合症的发生密切相关,其蛋白Parkin是细胞内的E3泛素连接酶。当线粒体受到损伤时,Parkin会募集到线粒体上,介导线粒体自噬,在生理条件下,Parkin及Parkin突变体是否会引起细胞自噬还不清楚。本文研究了病理性Parkin突变体对细胞自噬的影响。通过构建一系列Parkin功能缺失的突变体,并转染到HeLa以及ATG5-/-MEF细胞中,利用免疫荧光技术和Western-blot分析这些突变体对细胞自噬的影响。结果表明,Parkin突变体的表达促进细胞自噬的标志分子LC3由LC3-Ⅰ型变为LC3-Ⅱ型。突变体R275W在细胞内形成蛋白聚集体,并与LC3共定位。当细胞自噬的关键基因ATG5被敲除后,Parkin突变体引起的细胞自噬受到显著抑制。我们的初步结果提示Parkin突变体通过Atg5影响细胞自噬,并可能与帕金森症的发生有一定的相关性。

Parkin is an E3 ubiquitin ligase. Mutation of Parkin resulted in the altered ubiquitin ligase activity which appears to be the underlying mechanism of the pathogenesis of autosomal-recessive juvenile parkinsonism （AR-JP）. Parkin translocated to damaged mitochondria and mediated mitophagy. Whether Parkin or Parkin mutants can mediate autophagy is not fully understood. In this study, we investigated the effects of pathological mutation of Parkin on autophagy. A series of loss-of-function Parkin mutants were constructed and transfected into HeLa or ATG5- MEF cells. We detected the aggregation of LC3 in cells that expressing Parkin mutants, but not wild type counterpart. It was showed that the conversion of LC3-Ⅰ to LC3-Ⅱ was increased in cells expressing mutant Parkin and this conversion is completely inhibited in ATG5 knockout cells. Our results showed that Parkin mutants enhance autophagy through Atg5 which may correlate with the development of Parkinson＇s disease.