Role of cyclic AMP responsive element in the UVB induction of cyclooxygenase-2 transcription in human keratinocytes.
It has been shown that UVB irradiation induces expression of COX-2 and up-regulation of COX-2 plays a functional role in UVB tumor promotion. In this study, we examined the cis-elements in the human COX-2 promoter that may be responsible for the UVB induction of COX-2. Analyses with the COX-2 promoter region revealed that the cyclic AMP responsive element near the TATA box was essential for both basal and UVB induced COX-2 expression. This was further supported by studies using a dominant negative mutant of CREB, which strongly inhibited the activity of COX-2 promoter. Electrophoretic mobility shift assays indicated that CREB and ATF-1 were the major proteins binding to the COX-2 CRE. CREB and ATF-1 were phosphorylated upon UVB treatment, and SB202190, a p38 MAPK inhibitor, decreased the phosphorylation of CREB/ATF-1 and suppressed COX-2 promoter activity. In contrast, treatment with forskolin, an activator of adenylyl cyclase, led to phosphorylation of CREB and ATF-1 and activation of COX-2 promoter. Finally, enhanced binding of phospho-CREB/ATF-1 to the COX-2 CRE was observed after UVB induction. Thus, one signaling pathway for UVB induction of human COX-2 involves activation of p38, subsequent phosphorylation of CREB/ATF-1, and activation of the COX-2 CRE through enhanced binding of phosphorylated CREB/ATF-1.
Tang
Q
Q
Department of Radiation Oncology, Arizona Cancer Center, College of Medicine, The University of Arizona, 1515 North Campbell Avenue, Tucson, AZ 85724, USA.
Chen
W
W
Gonzales
M S
MS
Finch
J
J
Inoue
H
H
Bowden
G T
GT
D051697:Activating Transcription Factor 1; D002460:Cell Line; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism / Q000502:physiology*; D051546:Cyclooxygenase 2; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005799:Genes, Dominant; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics; D015603:Keratinocytes / Q000378:metabolism*; D008565:Membrane Proteins; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics; D011485:Protein Binding; D020218:Response Elements; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014466:Ultraviolet Rays; D015854:Up-Regulation
D051697:Activating Transcription Factor 1; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D014157:Transcription Factors; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases