HCV-induced autophagosomes are generated via homotypic fusion of phagophores that mediate HCV RNA replication

PLoS Pathogens

Ja Yeon Kim¹  Michael M. C. Lai¹  Linya Wang¹  Helene Minyi Liu²  Jing-hsiung James Ou³ 

[1] Department of Molecular Microbiology and Immunology, University of Southern California, Keck School of Medicine, Los Angeles, California, United States of America;Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan;Research Center for Emerging Viruses, China Medical University Hospital and China Medical University, Taichung, Taiwan

关键词: Small interfering RNAs;    Membrane fusion;    Hepatitis C virus;    Cell fusion;    Autophagic cell death;    Endoplasmic reticulum;    Cell staining;    Biosynthesis;   

DOI  :  10.1371/journal.ppat.1006609

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Hepatitis C virus (HCV) induces autophagy to promote its replication, including its RNA replication, which can take place on double-membrane vesicles known as autophagosomes. However, how HCV induces the biogenesis of autophagosomes and how HCV RNA replication complex may be assembled on autophagosomes were largely unknown. During autophagy, crescent membrane structures known as phagophores first appear in the cytoplasm, which then progress to become autophagosomes. By conducting electron microscopy and in vitro membrane fusion assay, we found that phagophores induced by HCV underwent homotypic fusion to generate autophagosomes in a process dependent on the SNARE protein syntaxin 7 (STX7). Further analyses by live-cell imaging and fluorescence microscopy indicated that HCV-induced phagophores originated from the endoplasmic reticulum (ER). Interestingly, comparing with autophagy induced by nutrient starvation, the progression of phagophores to autophagosomes induced by HCV took significantly longer time, indicating fundamental differences in the biogenesis of autophagosomes induced by these two different stimuli. As the knockdown of STX7 to inhibit the formation of autophagosomes did not affect HCV RNA replication, and purified phagophores could mediate HCV RNA replication, the assembly of the HCV RNA replication complex on autophagosomes apparently took place during the formative stage of phagophores. These findings provided important information for understanding how HCV controlled and modified this important cellular pathway for its own replication.

【 授权许可】

CC BY