title: miR-122 does not modulate the elongation phase of hepatitis C virus RNA synthesis in isolated replicase complexes.
abstract: miR-122 is an abundant, liver-specific microRNA that is required for efficient amplification of hepatitis C virus (HCV) RNA. Recent studies with a miR-122-specific locked nucleic acid antagomir have shown it to be an important host target for therapeutic intervention. However, considerable controversy exists concerning the mechanisms underlying the dependence of HCV replication on miR-122. We studied the impact of miR-122 on the rate of [(32)P]-incorporation into positive-strand viral RNA by membrane-bound replicase complexes isolated from cells containing HCV RNA replicons. [(32)P]-incorporation in this cell-free system represents primarily the elongation phase of RNA synthesis, with little or no de novo initiation, and was not affected by the addition of either excess miR-122 or a miR-122-specific antisense oligonucleotide that suppresses replication in vivo. We also found no evidence that detectable quantities of miR-122 are specifically associated with replicase complexes in vivo. These results are consistent with miR-122 acting at an alternative step in the viral life cycle, promoting cap-independent viral translation, enhancing viral RNA stability, or facilitating de novo initiation of viral RNA synthesis.
authors.affiliation: Laboratorio de Virus Hepatitis, Programa de Virología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile. Avda. Independencia 1027, Independencia 8380453, Santiago, Chile. rvillanueva@med.uchile.cl
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Villanueva
authors.forename: Rohit K
authors.initials: RK
authors.lastname: Jangra
authors.forename: Minkyung
authors.initials: M
authors.lastname: Yi
authors.forename: Rick
authors.initials: R
authors.lastname: Pyles
authors.forename: Nigel
authors.initials: N
authors.lastname: Bourne
authors.forename: Stanley M
authors.initials: SM
authors.lastname: Lemon
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D002474:Cell-Free System; D002478:Cells, Cultured; D015967:Gene Expression Regulation, Viral; D020868:Gene Silencing; D016174:Hepacivirus / Q000235:genetics* / Q000378:metabolism*; D022781:Hepatocytes; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D017354:Point Mutation; D020871:RNA Stability; D012367:RNA, Viral / Q000096:biosynthesis*; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism; D012093:Replicon; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000096:biosynthesis; D014779:Virus Replication / Q000235:genetics
chemical_list: D000998:Antiviral Agents; C531907:MIRN122 microRNA, human; D035683:MicroRNAs; D019384:Nucleic Acid Synthesis Inhibitors; D012367:RNA, Viral; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase