Molecular basis of estrogen-induced cyclooxygenase type 1 upregulation in endothelial cells.
Circ Res
; 96(5): 518-25, 2005 Mar 18.
Article
em En
| MEDLINE
| ID: mdl-15705965
ABSTRACT
Estrogen upregulates cyclooxygenase-1 (COX-1) expression in endothelial cells. To determine the basis of this process, studies were performed in ovine endothelial cells transfected with the human COX-1 promoter fused to luciferase. Estradiol (E2) caused activation of the COX-1 promoter with maximal stimulation at 10(-8) mol/L E2, and the response was mediated by either ERalpha or ERbeta. Mutagenesis revealed a primary role for a putative Sp1 binding motif at -89 (relative to the ATG codon) and lesser involvement of a consensus Sp1 site at -111. Electrophoretic mobility shift assays yielded a single complex with the site at -89, and supershift analyses implicated AP-2alpha and ERalpha, and not Sp1, in protein-DNA complex formation. In endothelial cells with minimal endogenous ER, the transfection of ERalpha mutants lacking the DNA binding domain or primary nuclear localization signals caused 4-fold greater stimulation of promoter activity with E2 than wild-type ERalpha. In contrast, mutant ERalpha lacking the A-B domains was inactive. Thus, estrogen-mediated upregulation of COX-1 in endothelium is uniquely independent of direct ERalpha-DNA binding and instead entails protein-DNA interaction involving AP-2alpha and ERalpha at a proximal regulatory element. In addition, the process may be initiated by cytoplasmic ERalpha, and critical receptor elements reside within the amino terminus.
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Base de dados:
MEDLINE
Assunto principal:
Fatores de Transcrição
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Ativação Transcricional
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Regiões Promotoras Genéticas
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Prostaglandina-Endoperóxido Sintases
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Receptor alfa de Estrogênio
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Proteínas de Ligação a DNA
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Estradiol
Idioma:
En
Ano de publicação:
2005
Tipo de documento:
Article