Transcriptional regulation of the cyclooxygenase-2 gene in activated mast cells.
Activation of mast cells by aggregation of their IgE receptors induces rapid and transient synthesis of cyclooxygenase-2 (COX-2). In this study we investigated (i) the cis-acting response elements and transcription factors active at the COX-2 promoter and (ii) the signal transduction pathways mediating COX-2 induction following aggregation of mast cell IgE receptors. Transient transfection assays with COX-2 promoter/luciferase constructs suggest that a consensus cyclic AMP response element is essential for induced COX-2 expression. Cotransfection studies with plasmids expressing c-Jun, dominant negative Ras, dominant negative c-Jun NH(2)-terminal kinase, and dominant negative MEKK1 demonstrate that activation of the Ras/MEKK1/c-Jun NH(2)-terminal kinase/c-Jun pathway is required for COX-2 promoter-mediated luciferase expression. Attenuation of COX-2 promoter activity by dominant negative constructs for Raf-1, ERK1, and ERK2 suggests that the Ras/Raf-1/extracellular signal-regulated kinase pathway is also necessary for COX-2 induction. Although mutating the two NF-IL6 sites individually did not affect COX-2 promoter activity, mutating both NF-IL6 sites substantially inhibits COX-2 promoter activity. Moreover, overexpression of wild type CCAAT/enhancer-binding protein-beta (C/EBPbeta) augments COX-2 promoter activity in activated mast cells and cotransfection of a dominant negative C/EBPbeta construct completely blocks COX-2 promoter/luciferase expression. Our data suggest that in activated mast cells, a Ras/MEKK1/c-Jun NH(2)-terminal kinase signal transduction pathway activating c-Jun, a Ras/Raf-1/extracellular signal-regulated kinase pathway, and activated C/EBPbeta facilitate COX-2 induction via the cyclic AMP response element and NF-IL6 sites of the COX-2 promoter.
Reddy
S T
ST
Molecular Biology Institute, UCLA-Los Angeles Center for the Health Sciences, Los Angeles, California 90095, USA.
Wadleigh
D J
DJ
Herschman
H R
HR
D000818:Animals; D002460:Cell Line; D051546:Cyclooxygenase 2; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000235:genetics*; D008407:Mast Cells / Q000502:physiology*; D051379:Mice; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D017455:Receptors, IgE / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D014158:Transcription, Genetic
D007527:Isoenzymes; D017455:Receptors, IgE; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases