Affiliation:
1. From the Vascular Biology Research Center, Institute of Molecular Medicine and Division of Hematology, University of Texas Health Science Center, Houston, TX.
Abstract
Abstract
Coactivators p300 and CREB (cyclic adenosine monophosphate [cAMP]–response element binding protein)–binding protein (CBP) serve as an integrator for gene transcription. Their relative involvement in regulating cyclooxygenase-2 (COX-2) promoter activity had not been characterized. Using fibroblast and macrophage COX-2 transcription as a model, we determined p300 and CBP levels in nuclear extracts and their binding to a COX-2 promoter probe. CBP level was barely detectable and there was little CBP binding. In contrast, p300 was detectable in nucleus and its binding to a COX-2 promoter probe was enhanced by phorbol 12-myristate 13-acetate (PMA), interleukin-1β (IL-1β), or lipopolysaccharide (LPS). Binding of p300/CBP-associated factor (PCAF) was also up-regulated. COX-2 proteins and promoter activities induced by these agonists were augmented by p300 overexpression. Early region 1A (E1A), but not its deletion mutant, abrogated COX-2 expression induced by inflammatory mediators and with or without p300 overexpression. Molecular analysis of p300 revealed the requirement of multiple domains, including histone acetyltransferase (HAT) for COX-2 transactivation. Furthermore, roscovitine, an indirect inhibitor of p300 HAT, and histone deacetylase-1 transfection completely abolished COX-2 promoter activity. We conclude that p300 is the predominant coactivator that is essential for COX-2 transcriptional activation by proinflammatory mediators.
Publisher
American Society of Hematology
Subject
Cell Biology,Hematology,Immunology,Biochemistry
Cited by
122 articles.
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