Differential stimulation of hepatitis C virus RNA translation by microRNA-122 in different cell cycle phases

Cell Cycle. 2012 Jan 15;11(2):277-85. doi: 10.4161/cc.11.2.18699. Epub 2012 Jan 15.

Abstract

Hepatitis C virus (HCV) replicates preferentially in the liver, and in most cases the HCV infection becomes chronic and often results in hepatocellular carcinoma. When the HCV plus-strand RNA genome has been delivered to the cytosol of the infected cell, its translation is directed by the Internal Ribosome Entry Site (IRES) in the 5'-untranslated region (5'-UTR) of the viral RNA. Thereby, IRES activity is modulated by several host factors. In particular, the liver-specific microRNA-122 (miR-122) interacts with two target sites in the HCV 5'-UTR and stimulates HCV translation, thereby most likely contributing to HCV liver tropism. Here we show that HCV IRES-dependent translation efficiency in the hepatoma cell line Huh7 is highest during the G₀ and G₁ phases of the cell cycle but significantly drops during the S phase and even more in the G₂/M phase. The superimposed stimulation of HCV translation by ectopic miR-122 works best during the G₀, G₁ and G₂/M phases but is lower during the S phase. However, the levels of Ago2 protein do not substantially change during cell cycle phases, indicating that other cellular factors involved in HCV translation stimulation by miR-122 may be differentially expressed in different cell cycle phases. Moreover, the levels of endogenously expressed miR-122 in Huh7 cells are lowest in the S phase, indicating that the predominant G₀/G₁ state of non-dividing hepatocytes in the liver facilitates high expression of the HCV genome and stimulation by miR-122, with yet unknown factors involved in the differential extent of stimulation by miR-122.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Argonaute Proteins / genetics
  • Argonaute Proteins / metabolism
  • Cell Line, Tumor
  • Gene Expression
  • Gene Expression Regulation, Viral*
  • Genes, Reporter
  • Genes, Viral
  • Hepacivirus / genetics
  • Hepacivirus / physiology*
  • Hepatitis C / virology
  • Humans
  • Interphase*
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Protein Biosynthesis*
  • RNA Interference
  • RNA, Small Nuclear / metabolism
  • RNA, Viral / genetics*

Substances

  • AGO2 protein, human
  • Argonaute Proteins
  • MIRN122 microRNA, human
  • MicroRNAs
  • RNA, Small Nuclear
  • RNA, Viral
  • U6 small nuclear RNA