Role of p300 and PCAF in regulating cyclooxygenase-2 promoter activation by inflammatory mediators.

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-1 beta(IL-1 beta), 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.
Mesh Terms:
Adenovirus E1A Proteins, CREB-Binding Protein, Carcinogens, Cell Line, Cyclic AMP Response Element-Binding Protein, Cyclooxygenase 2, DNA-Binding Proteins, Enzyme Inhibitors, Gene Expression, Histone Deacetylase 1, Histone Deacetylases, Humans, Inflammation Mediators, Interleukin-1, Isoenzymes, Lipopolysaccharides, Membrane Proteins, Mutagenesis, Nuclear Proteins, Promoter Regions, Genetic, Prostaglandin-Endoperoxide Synthases, Purines, Tetradecanoylphorbol Acetate, Trans-Activators, Transcription Factors, Transfection, Up-Regulation
Blood
Date: Mar. 15, 2004
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