Hepatitis C virus core protein suppresses mitophagy by interacting with Parkin
Yuichi Hara1, Sohji Nishina1, Izumi Yanatori4, Masanori Ikeda2, Emi Kiyokage5, Yasuyuki Tomiyama1, Kazunori Toida5, Fumio Kishi4, Nobuyuki Kato2, Michio Imamura3, Kazuaki Chayama3, Keisuke Hino1
1Departments of Hepatology and Pancreatology, kawasakimedicalschool, Kurashiki, Japan; 2Department of Gastroenterology and Metabolism, Applied Life Sciences, Institute of Biomedical and Health Sciences, Hiroshima Univercity, Hiroshima, Japan; 3Department of Tumor Virology, Okayama Univercity, Okayama, Japan; 4Molecular Genetics, Kawasaki Medical School, Okayama, Japan; 5Anatomy, Kawasaki Medical School, Okayama, Japan
BACKGROUND and AIM: Hepatitis C virus (HCV) causes mitochondrial injury and oxidative stress, and impaired mitochondria are selectively eliminated through autophagy-dependent degradation (mitophagy). However, whether HCV infection affects mitophagy in terms of mitochondrial quality control remains unknown. METHODS: The effect of HCV on mitophagy was examined using HCV-JFH1-infected cells, genome-length HCV RNA-replicating cells (OR6 cells), HCV core-expressing cells and the uncoupling reagent carbonyl cyanide mchlorophenylhydrazone as a mitophagy inducer in addition to liver cells from HCV-infected human hepatocyte chimeric mice and. transgenic mice expressing the HCV polyprotein. RESULTS : The results indicated that translocation of the E3 ubiquitin ligase Parkin to the mitochondria was impaired without reduction of PTEN-induced putative kinase 1activity in the presence of HCV infection both in vitro and in vivo. Co-immunoprecipitation revealed that Parkin was associated with the HCV core protein but not other HCV proteins, such as NS3, NS4A and NS5A. Furthermore, a yeast two-hybrid assay identified a specific interaction between the HCV core protein and an N-terminal Parkin fragment that contains one of the amino acids that is essential for its mitochondrial localization. Silencing Parkin suppressed HCV replication suggesting the functional role of interaction between HCV core protein and Parkin in HCV propagation. The suppressed translocation of Parkin to the mitochondria inhibited mitochondrial ubiquitination'decreased the number of mitochondria sequestered in isolation membranes (mitophagosomes), and reduced autophagic degradation activity, which clearly indicated the suppression of mitophagy. However, OR6 cells promoted autophagy under non-selective autophagyinducible conditions (amino acid starvation), as indicated by the increased expression of the microtubule-associated protein light chain 3 (LC3)-II. CONCLUSIONS: Through a direct interaction with Parkin, the HCV core protein suppressed mitophagy by inhibiting the translocation of Parkin to the mitochondria. These results have implications for the amplification and sustainability of mitochondria-induced oxidative stress observed in patients with HCV-related chronic liver disease and an increased risk of hepatocarcinogenesis.
Kazuaki Chayama - Consulting: Abbvie; Grant/Research Support: Dainippon Sumitomo, Chugai, Mitsubishi Tanabe, DAIICHI SANKYO, Toray, BMS, MSD; Speaking and Teaching: Chugai, Mitsubishi Tanabe, DAIICHI SANKYO, KYORIN, Nihon Medi-Physics, BMS, Dainippon Sumitomo, MSD, ASKA, Astellas, AstraZeneca, Eisai, Olympus, GlaxoSmithKline, ZERIA, Bayer, Minophagen, JANSSEN, JIMTO, TSUMUTA, Otsuka, Taiho, Nippon Kayaku, Nippon Shinyaku, Takeda, AJINOMOTO, Meiji Seika, Toray
The following people have nothing to disclose: Yuichi Hara, Sohji Nishina, Izumi Yanatori, Masanori Ikeda, Emi Kiyokage, Yasuyuki Tomiyama, Kazunori Toida, Fumio Kishi, Nobuyuki Kato, Michio Imamura, Keisuke Hino