title: The Dual Role of an ESCRT-0 Component HGS in HBV Transcription and Naked Capsid Secretion.
abstract: The Endosomal Sorting Complex Required for Transport (ESCRT) is an important cellular machinery for the sorting and trafficking of ubiquitinated cargos. It is also known that ESCRT is required for the egress of a number of viruses. To investigate the relationship between ESCRT and hepatitis B virus (HBV), we conducted an siRNA screening of ESCRT components for their potential effect on HBV replication and virion release. We identified a number of ESCRT factors required for HBV replication, and focused our study here on HGS (HRS, hepatocyte growth factor-regulated tyrosine kinase substrate) in the ESCRT-0 complex. Aberrant levels of HGS suppressed HBV transcription, replication and virion secretion. Hydrodynamic delivery of HGS in a mouse model significantly suppressed viral replication in the liver and virion secretion in the serum. Surprisingly, overexpression of HGS stimulated the release of HBV naked capsids, irrespective of their viral RNA, DNA, or empty contents. Mutant core protein (HBc 1-147) containing no arginine-rich domain (ARD) failed to secrete empty virions with or without HGS. In contrast, empty naked capsids of HBc 1-147 could still be promoted for secretion by HGS. HGS exerted a strong positive effect on the secretion of naked capsids, at the expense of a reduced level of virions. The association between HGS and HBc appears to be ubiquitin-independent. Furthermore, HBc is preferentially co-localized with HGS near the cell periphery, instead of near the punctate endosomes in the cytoplasm. In summary, our work demonstrated the importance of an optimum level of HGS in HBV propagation. In addition to an effect on HBV transcription, HGS can diminish the pool size of intracellular nucleocapsids with ongoing genome maturation, probably in part by promoting the secretion of naked capsids. The secretion routes of HBV virions and naked capsids can be clearly distinguished based on the pleiotropic effect of HGS involved in the ESCRT-0 complex.
authors.affiliation: Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
authors.forename: Shu-Fan
authors.initials: SF
authors.lastname: Chou
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
authors.forename: Ming-Lin
authors.initials: ML
authors.lastname: Tsai
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan; Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Jyun-Yuan
authors.initials: JY
authors.lastname: Huang
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
authors.forename: Ya-Shu
authors.initials: YS
authors.lastname: Chang
authors.affiliation: Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
authors.forename: Chiaho
authors.initials: C
authors.lastname: Shih
mesh_terms: D000818:Animals; D002213:Capsid / Q000378:metabolism*; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006509:Hepatitis B / Q000378:metabolism; D006515:Hepatitis B virus / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism*; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D014158:Transcription, Genetic; D014162:Transfection; D014779:Virus Replication / Q000502:physiology*
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D010750:Phosphoproteins; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate