Cochaperone activity of human butyrate-induced transcript 1 facilitates hepatitis C virus replication through an Hsp90-dependent pathway

J Virol. 2009 Oct;83(20):10427-36. doi: 10.1128/JVI.01035-09. Epub 2009 Aug 5.

Abstract

Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is a component of the replication complex consisting of several host and viral proteins. We have previously reported that human butyrate-induced transcript 1 (hB-ind1) recruits heat shock protein 90 (Hsp90) and FK506-binding protein 8 (FKBP8) to the replication complex through interaction with NS5A. To gain more insights into the biological functions of hB-ind1 in HCV replication, we assessed the potential cochaperone-like activity of hB-ind1, because it has significant homology with cochaperone p23, which regulates Hsp90 chaperone activity. The chimeric p23 in which the cochaperone domain was replaced with the p23-like domain of hB-ind1 exhibited cochaperone activity comparable to that of the authentic p23, inhibiting the glucocorticoid receptor signaling in an Hsp90-dependent manner. Conversely, the chimeric hB-ind1 in which the p23-like domain was replaced with the cochaperone domain of p23 resulted in the same level of recovery of HCV propagation as seen in the authentic hB-ind1 in cells with knockdown of the endogenous hB-ind1. Immunofluorescence analyses revealed that hB-ind1 was colocalized with NS5A, FKBP8, and double-stranded RNA in the HCV replicon cells. HCV replicon cells exhibited a more potent unfolded-protein response (UPR) than the parental and the cured cells upon treatment with an inhibitor for Hsp90. These results suggest that an Hsp90-dependent chaperone pathway incorporating hB-ind1 is involved in protein folding in the membranous web for the circumvention of the UPR and that it facilitates HCV replication.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cell Line, Tumor
  • Gene Expression Regulation
  • HSP90 Heat-Shock Proteins / genetics
  • HSP90 Heat-Shock Proteins / metabolism*
  • Hepacivirus / drug effects
  • Hepacivirus / metabolism
  • Hepacivirus / pathogenicity
  • Hepacivirus / physiology*
  • Humans
  • Hydro-Lyases
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Kidney / cytology
  • Kidney / virology
  • Liver / cytology
  • Liver / virology
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism
  • Molecular Chaperones / pharmacology
  • Protein Folding
  • Virus Replication / drug effects
  • Virus Replication / physiology*

Substances

  • HSP90 Heat-Shock Proteins
  • Intracellular Signaling Peptides and Proteins
  • Molecular Chaperones
  • HACD3 protein, human
  • Hydro-Lyases