IFN-gamma-induced MHC class II expression: transactivation of class II transactivator promoter IV by IFN regulatory factor-1 is regulated by protein kinase C-alpha

J Immunol. 2003 Oct 15;171(8):4187-94. doi: 10.4049/jimmunol.171.8.4187.

Abstract

Previous studies based on pharmacological evidence suggested a requirement for protein kinase C (PKC) activity in the regulation of IFN-gamma-induced MHC class II (MHC-II) expression. In the present study, we investigated the molecular mechanisms by which PKC-alpha modulates IFN-gamma-induced MHC-II expression in the mouse macrophage cell line RAW 264.7. Overexpression of a dominant-negative (DN) mutant of PKC-alpha inhibited the expression of IFN-gamma-induced MHC-II but had no effect on IFN-gamma-induced STAT1 nuclear translocation and DNA binding activity, as well as on the expression of inducible NO synthase, IFN consensus sequence binding protein, MHC class I, IFN regulatory factor (IRF)-1, and IFN-gamma-inducible protein-10. Further analysis showed that IFN-gamma-induced expression of the MHC class II transactivator (CIITA), a transcriptional coactivator essential for MHC-II expression, was inhibited in DN PKC-alpha-overexpressing cells. Studies with reporter constructs containing the promoter IV region of CIITA revealed that overexpression of a constitutively active mutant of PKC-alpha enhanced IRF-1, but not IRF-2, transcriptional activity. Furthermore, characterization of IRF-1 from both normal and DN PKC-alpha-overexpressing cells revealed differences in IRF-1 posttranslational modifications. Collectively, our data suggest a novel regulatory mechanism for IFN-gamma-induced MHC-II expression, whereby PKC regulates CIITA expression by selectively modulating the transcriptional activity of IRF-1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • DNA-Binding Proteins / physiology*
  • Histocompatibility Antigens Class II / biosynthesis*
  • Histocompatibility Antigens Class II / genetics
  • Humans
  • Interferon Regulatory Factor-1
  • Interferon Regulatory Factor-2
  • Interferon-gamma / physiology*
  • Isoenzymes / physiology
  • Mice
  • Nuclear Proteins*
  • Phosphoproteins / biosynthesis
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Phosphoproteins / physiology*
  • Promoter Regions, Genetic / immunology*
  • Protein Kinase C / biosynthesis
  • Protein Kinase C / genetics
  • Protein Kinase C / physiology*
  • Protein Kinase C-alpha
  • Protein Processing, Post-Translational / genetics
  • Protein Processing, Post-Translational / immunology
  • RNA, Messenger / antagonists & inhibitors
  • RNA, Messenger / metabolism
  • Repressor Proteins*
  • Trans-Activators / genetics*
  • Trans-Activators / metabolism*
  • Transcription Factors*
  • Transcriptional Activation / immunology*
  • Transfection
  • Up-Regulation / genetics
  • Up-Regulation / immunology

Substances

  • DNA-Binding Proteins
  • Histocompatibility Antigens Class II
  • IRF1 protein, human
  • IRF2 protein, human
  • Interferon Regulatory Factor-1
  • Interferon Regulatory Factor-2
  • Irf1 protein, mouse
  • Irf2 protein, mouse
  • Isoenzymes
  • MHC class II transactivator protein
  • Nuclear Proteins
  • Phosphoproteins
  • RNA, Messenger
  • Repressor Proteins
  • Trans-Activators
  • Transcription Factors
  • Interferon-gamma
  • PRKCA protein, human
  • Prkca protein, mouse
  • Protein Kinase C
  • Protein Kinase C-alpha