title: Hepatitis C Virus Core Protein Promotes miR-122 Destabilization by Inhibiting GLD-2.
abstract: The liver-specific microRNA miR-122, which has essential roles in liver development and metabolism, is a key proviral factor for hepatitis C virus (HCV). Despite its crucial role in the liver and HCV life cycle, little is known about the molecular mechanism of miR-122 expression regulation by HCV infection. Here, we show that the HCV core protein downregulates the abundance of miR-122 by promoting its destabilization via the inhibition of GLD-2, a non-canonical cytoplasmic poly(A) polymerase. The decrease in miR-122 expression resulted in the dysregulation of the known functions of miR-122, including its proviral activity for HCV. By high-throughput sequencing of small RNAs from human liver biopsies, we found that the 22-nucleotide (nt) prototype miR-122 is modified at its 3' end by 3'-terminal non-templated and templated nucleotide additions. Remarkably, the proportion of miR-122 isomers bearing a single nucleotide tail of any ribonucleotide decreased in liver specimens from patients with HCV. We found that these single-nucleotide-tailed miR-122 isomers display increased miRNA activity and stability over the 22-nt prototype miR-122 and that the 3'-terminal extension is catalyzed by the unique terminal nucleotidyl transferase activity of GLD-2, which is capable of adding any single ribonucleotide without preference of adenylate to the miR-122 3' end. The HCV core protein specifically inhibited GLD-2, and its interaction with GLD-2 in the cytoplasm was found to be responsible for miR-122 downregulation. Collectively, our results provide new insights into the regulatory role of the HCV core protein in controlling viral RNA abundance and miR-122 functions through miR-122 stability modulation.
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul, Korea.
authors.forename: Geon-Woo
authors.initials: GW
authors.lastname: Kim
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul, Korea.
authors.forename: Seung-Hoon
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul, Korea.
authors.forename: Hee
authors.initials: H
authors.lastname: Cho
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul, Korea.
authors.forename: Minwoo
authors.initials: M
authors.lastname: Kim
authors.affiliation: Laboratory of Immunology and Infectious Diseases, Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea.
authors.forename: Eui-Cheol
authors.initials: EC
authors.lastname: Shin
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul, Korea.
authors.forename: Jong-Won
authors.initials: JW
authors.lastname: Oh
mesh_terms: D000818:Animals; D016174:Hepacivirus / Q000378:metabolism* / Q000472:pathogenicity; D006526:Hepatitis C / Q000378:metabolism; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D035683:MicroRNAs / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011062:Polynucleotide Adenylyltransferase; D014758:Viral Core Proteins / Q000378:metabolism*; D039221:mRNA Cleavage and Polyadenylation Factors / Q000378:metabolism*
chemical_list: C531907:MIRN122 microRNA, human; D035683:MicroRNAs; D014758:Viral Core Proteins; D039221:mRNA Cleavage and Polyadenylation Factors; C069130:nucleocapsid protein, Hepatitis C virus; D011062:Polynucleotide Adenylyltransferase; C550174:TENT2 protein, human