Type I IFN induced IL1-Ra expression in hepatocytes is mediated by activating STAT6 through the formation of STAT2: STAT6 heterodimer

J Cell Mol Med. 2008 Jun;12(3):876-88. doi: 10.1111/j.1582-4934.2008.00143.x.

Abstract

The biological activities of type I interferons (IFNs) are mediated by their binding to a heterodimer receptor complex (IFNAR1 and IFNAR2), resulting in the activation of the JAK (JAK1 and TYK2)-STAT (1, 2, 3, 5 isotypes) signalling pathway. Although several studies have indicated that IFN-alpha and IFN-beta can activate complexes containing STAT6, the biological role of this activation is still unknown. We found that exposure of hepatoma cells (HuH7 and Hep3B) to IFN-alpha or IFN-beta led to the activation of STAT6. Activated STAT6 in turn induced the formation of STAT2: STAT6 complexes, which led to the secretion of IL-1Ra. The activation of STAT6 by type I IFN in hepatocytes was mediated by JAK1 and Tyk2. In addition, IFN-alpha or IFN-beta significantly enhanced the stimulatory effect of IL-1beta on production of IL-1Ra. The present study suggests a novel function of IFN-alpha and IFN-beta signalling in human hepatocytes. Our results provide evidence for the mechanism how IFN-alpha and IFN-beta modulate inflammatory responses through activation of STAT6 and production of secreted IL-1Ra.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinoma, Hepatocellular / metabolism
  • Carcinoma, Hepatocellular / pathology
  • Cell Line, Tumor
  • Dimerization
  • Hepatocytes / drug effects
  • Hepatocytes / metabolism*
  • Humans
  • Interferon Type I / pharmacology*
  • Interferon-alpha / pharmacology
  • Interferon-beta / pharmacology
  • Interleukin 1 Receptor Antagonist Protein / biosynthesis
  • Interleukin 1 Receptor Antagonist Protein / genetics
  • Interleukin 1 Receptor Antagonist Protein / metabolism*
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / pathology
  • Models, Biological
  • Phosphorylation
  • STAT2 Transcription Factor / metabolism*
  • STAT6 Transcription Factor / metabolism*

Substances

  • IL1RN protein, human
  • Interferon Type I
  • Interferon-alpha
  • Interleukin 1 Receptor Antagonist Protein
  • STAT2 Transcription Factor
  • STAT6 Transcription Factor
  • STAT6 protein, human
  • Interferon-beta