Protein kinase C-theta participates in the activation of cyclic AMP-responsive element-binding protein and its subsequent binding to the -180 site of the IL-2 promoter in normal human T lymphocytes.
IL-2 gene expression is regulated by the cooperative binding of discrete transcription factors to the IL-2 promoter/enhancer and is predominantly controlled at the transcriptional level. In this study, we show that in normal T cells, the -180 site (-164/-189) of the IL-2 promoter/enhancer is a p-cAMP-responsive element-binding protein (p-CREB) binding site. Following activation of the T cells through various membrane-initiated and membrane-independent pathways, protein kinase C (PKC)-theta phosphorylates CREB, which subsequently binds to the -180 site and associates with the transcriptional coactivator p300. Rottlerin, a specific PKC-theta inhibitor, diminished p-CREB protein levels when normal T cells were treated with it. Rottlerin also prevented the formation of p-CREB/p300 complexes and the DNA-CREB protein binding. Cotransfection of fresh normal T cells with luciferase reporter construct driven by two tandem -180 sites and a PKC-theta construct caused a significant increase in the transcription of the reporter gene, indicating that this site is functional and regulated by PKC-theta. Cotransfection of T cells with a luciferase construct driven by the -575/+57 region of the IL-2 promoter/enhancer and a PKC-theta construct caused a similar increase in the reporter gene transcription, which was significantly limited when two bases within the -180 site were mutated. These findings show that CREB plays a major role in the transcriptional regulation of IL-2 and that a major pathway for the activation of CREB and its subsequent binding to the IL-2 promoter/enhancer in normal T cells is mediated by PKC-theta.
Solomou
E E
EE
Department of Cellular Injury, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA.
Juang
Y T
YT
Tsokos
G C
GC
D000098:Acetophenones / Q000494:pharmacology; D000276:Adjuvants, Immunologic / Q000378:metabolism / Q000502:physiology; D001483:Base Sequence; D001578:Benzopyrans / Q000494:pharmacology; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D017362:Cyclic AMP Response Element-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017930:Genes, Reporter / Q000276:immunology; D051548:Histone Acetyltransferases; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics* / Q000378:metabolism*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D008156:Luciferases / Q000235:genetics; D056921:Nuclear Receptor Coactivator 3; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000276:immunology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D000074121:Protein Kinase C-theta; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D015534:Trans-Activators / Q000037:antagonists & inhibitors / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects / Q000276:immunology
D000098:Acetophenones; D000276:Adjuvants, Immunologic; D001578:Benzopyrans; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D007376:Interleukin-2; D007527:Isoenzymes; D015534:Trans-Activators; C085746:rottlerin; D008156:Luciferases; D051548:Histone Acetyltransferases; C538866:NCOA3 protein, human; D056921:Nuclear Receptor Coactivator 3; C076233:PRKCQ protein, human; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta