Roles of phosphatidylinositol 3-kinase and p38 mitogen-activated protein kinase in the regulation of protein kinase C-alpha activation in interferon-gamma-stimulated macrophages.
Members of the protein kinase C (PKC) family are activated by interferon-gamma (IFN-gamma) and modulate IFN-gamma-induced cellular responses by regulating the activity of transcription factors. We previously reported that PKC-alpha enhances the ability of IFN regulatory factor-1 to transactivate the class II transactivator (CIITA) promoter IV in IFN-gamma-stimulated macrophages. In addition, we showed that IFN-gamma induces the nuclear translocation of PKC-alpha but the mechanisms for this remain to be elucidated. In this study, we sought to identify signalling pathways involved in IFN-gamma-induced activation of PKC-alpha and to characterize their potential roles in modulating IFN-gamma-induced responses in macrophages. IFN-gamma-mediated nuclear translocation of PKC-alpha was a Janus activated kinase 2 (JAK2)-independent process, which required phosphatidylinositol 3-kinase (PI3K) and p38 mitogen-activated protein kinase (MAPK). However, PKC-alpha phosphorylation was independent of PI3K and p38 MAPK, indicating that IFN-gamma-induced phosphorylation and nuclear translocation of PKC-alpha are mediated by distinct mechanisms. In addition, inhibition of PI3K, but not of p38 MAPK, strongly impaired IFN-gamma-induced CIITA and MHC II gene expression. Finally, PKC-alpha associated with signal transducer and activator of transcription 1 (STAT1) and was required for the phosphorylation of STAT1 on serine 727 in IFN-gamma-stimulated macrophages. Taken together, our data indicate that PI3K and p38 MAPK modulate IFN-gamma-stimulated PKC-alpha nuclear translocation independently of JAK2 activity and that both PI3K and PKC-alpha are required for type IV CIITA and MHC II gene expression in IFN-gamma-stimulated macrophages.
Hardy
Pierre-Olivier
PO
INRS-Institut Armand-Frappier, Laval, QC, Canada.
Diallo
Tamsir O
TO
Matte
Christine
C
Descoteaux
Albert
A
D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology*; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007093:Imidazoles / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009025:Morpholines / Q000494:pharmacology; D009687:Nuclear Proteins / Q000187:drug effects / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D050794:STAT1 Transcription Factor / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators / Q000187:drug effects / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D002867:Chromones; D004791:Enzyme Inhibitors; D007093:Imidazoles; D007371:Interferon-gamma; D053614:Janus Kinase 2; D009025:Morpholines; D009687:Nuclear Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051571:Protein Kinase C-alpha; D011725:Pyridines; D050794:STAT1 Transcription Factor; D015534:Trans-Activators; D020032:Tyrphostins; D048051:p38 Mitogen-Activated Protein Kinases; C083728:MHC class II transactivator protein; C494080:Stat1 protein, mouse; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093642:SB 203580