Williams Jessica A, Ni Hong-Min, Haynes Anna, Manley Sharon, Li Yuan, Jaeschke Hartmut, Ding Wen-Xing
From the Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160.
From the Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160
J Biol Chem. 2015 Apr 24;290(17):10934-46. doi: 10.1074/jbc.M114.602284. Epub 2015 Mar 9.
We previously demonstrated that pharmacological induction of autophagy protected against acetaminophen (APAP)-induced liver injury in mice by clearing damaged mitochondria. However, the mechanism for removal of mitochondria by autophagy is unknown. Parkin, an E3 ubiquitin ligase, has been shown to be required for mitophagy induction in cultured mammalian cells following mitochondrial depolarization, but its role in vivo is not clear. The purpose of this study was to investigate the role of Parkin-mediated mitophagy in protection against APAP-induced liver injury. We found that Parkin translocated to mitochondria in mouse livers after APAP treatment followed by mitochondrial protein ubiquitination and mitophagy induction. To our surprise, we found that mitophagy still occurred in Parkin knock-out (KO) mice after APAP treatment based on electron microscopy analysis and Western blot analysis for some mitochondrial proteins, and Parkin KO mice were protected against APAP-induced liver injury compared with wild type mice. Mechanistically, we found that Parkin KO mice had decreased activated c-Jun N-terminal kinase (JNK), increased induction of myeloid leukemia cell differentiation protein (Mcl-1) expression, and increased hepatocyte proliferation after APAP treatment in their livers compared with WT mice. In contrast to chronic deletion of Parkin, acute knockdown of Parkin in mouse livers using adenovirus shRNA reduced mitophagy and Mcl-1 expression but increased JNK activation after APAP administration, which exacerbated APAP-induced liver injury. Therefore, chronic deletion (KO) and acute knockdown of Parkin have differential responses to APAP-induced mitophagy and liver injury in mice.
我们之前证明，自噬的药理学诱导通过清除受损线粒体来保护小鼠免受对乙酰氨基酚（APAP）诱导的肝损伤。然而，自噬清除线粒体的机制尚不清楚。Parkin是一种E3泛素连接酶，已被证明在培养的哺乳动物细胞线粒体去极化后诱导线粒体自噬中是必需的，但其在体内的作用尚不清楚。本研究的目的是探讨Parkin介导的线粒体自噬在保护免受APAP诱导的肝损伤中的作用。我们发现，APAP处理后，Parkin在小鼠肝脏中易位至线粒体，随后发生线粒体蛋白泛素化和线粒体自噬诱导。令我们惊讶的是，基于电子显微镜分析和对一些线粒体蛋白的蛋白质印迹分析，我们发现在APAP处理后的Parkin基因敲除（KO）小鼠中仍发生线粒体自噬，并且与野生型小鼠相比，Parkin KO小鼠免受APAP诱导的肝损伤。从机制上讲，我们发现与野生型小鼠相比，Parkin KO小鼠在APAP处理后肝脏中活化的c-Jun氨基末端激酶（JNK）减少，髓样白血病细胞分化蛋白（Mcl-1）表达的诱导增加，肝细胞增殖增加。与Parkin的慢性缺失相反，使用腺病毒短发夹RNA在小鼠肝脏中急性敲低Parkin可减少线粒体自噬和Mcl-1表达，但在给予APAP后增加JNK活化，这加剧了APAP诱导的肝损伤。因此，Parkin的慢性缺失（KO）和急性敲低对小鼠中APAP诱导的线粒体自噬和肝损伤有不同的反应。
