Dynamic regulation of cyclooxygenase-2 promoter activity by isoforms of CCAAT/enhancer-binding proteins.
To elucidate the mechanism by which isoforms of CCAAT/enhancer-binding proteins regulate cyclooxygenase-2 expression, we determined by a novel technique binding of six isoforms of this transactivator to two sequence-specific CCAAT/enhancer-binding protein (-132/-125) and cyclic AMP (-59/-53) regulatory elements in human foreskin fibroblasts treated with phorbol 12-myristate 13-acetate for 4 h. The delta isoform bound to these two elements at basal state, which was displaced by full-length as well as two truncated beta isoforms, a 41-kDa liver-enriched activating protein and a 16-kDa liver-enriched inhibitory protein, after phorbol ester stimulation. Kinetic analysis shows time-dependent changes in beta and delta binding that were concordant with time-dependent increase in cyclooxygenase-2 induction. Overexpression of the 16-kDa beta isoform blocked the promoter activity and protein level induced by phorbol ester. Paradoxically, it increased binding of beta isoforms to the sequence-specific promoter DNA but suppressed cyclooxygenase-2 promoter activation by p300 cotransfection. These findings provide new insight into the regulation of cyclooxygenase-2 promoter by an interplay between two opposite beta isoforms and p300 co-activator.
Zhu
Ying
Y
Vascular Biology Research Center, Institute of Molecular Medicine, University of Texas-Houston Medical School, 6431 Fannin, Houston, TX 77030, USA.
Saunders
Michael A
MA
Yeh
Howard
H
Deng
Wu-guo
WG
Wu
Kenneth K
KK
D000123:Acetyltransferases / Q000378:metabolism; D001665:Binding Sites; D015153:Blotting, Western; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D051546:Cyclooxygenase 2; D004247:DNA / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D051548:Histone Acetyltransferases; D006801:Humans; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins; D010703:Phorbol Esters / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics* / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms; D013997:Time Factors; D014157:Transcription Factors; D014158:Transcription, Genetic; D014162:Transfection; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
D000123:Acetyltransferases; D022762:CCAAT-Enhancer-Binding Proteins; D018797:Cell Cycle Proteins; D051546:Cyclooxygenase 2; D004247:DNA; D051548:Histone Acetyltransferases; D007527:Isoenzymes; D008565:Membrane Proteins; D010703:Phorbol Esters; D011451:Prostaglandin-Endoperoxide Synthases; D020033:Protein Isoforms; D014157:Transcription Factors; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C119222:phorbol-12-myristate; C496540:PTGS2 protein, human