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About the Authors:
Linya Wang
Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Validation, Visualization, Writing - original draft, Writing - review & editing
Affiliation: Department of Molecular Microbiology and Immunology, University of Southern California, Keck School of Medicine, Los Angeles, California, United States of America
Ja Yeon Kim
Roles Conceptualization, Formal analysis, Investigation, Methodology
Affiliation: Department of Molecular Microbiology and Immunology, University of Southern California, Keck School of Medicine, Los Angeles, California, United States of America
Helene Minyi Liu
Roles Investigation, Methodology
Affiliation: Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
Michael M. C. Lai
Roles Resources
Affiliations Department of Molecular Microbiology and Immunology, University of Southern California, Keck School of Medicine, Los Angeles, California, United States of America, Research Center for Emerging Viruses, China Medical University Hospital and China Medical University, Taichung, Taiwan
ORCID http://orcid.org/0000-0002-5206-9451
Jing-hsiung James Ou
Roles Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Visualization, Writing - original draft, Writing - review & editing
* E-mail: [email protected]
Affiliation: Department of Molecular Microbiology and Immunology, University of Southern California, Keck School of Medicine, Los Angeles, California, United States of America
ORCID http://orcid.org/0000-0002-8274-5705Abstract
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...