Dynamic regulation of cyclooxygenase-2 promoter activity by isoforms of CCAAT/enhancer-binding proteins

J Biol Chem. 2002 Mar 1;277(9):6923-8. doi: 10.1074/jbc.M108075200. Epub 2001 Dec 10.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetyltransferases / metabolism
  • Binding Sites
  • Blotting, Western
  • CCAAT-Enhancer-Binding Proteins / metabolism*
  • Cell Cycle Proteins / metabolism
  • Cell Line
  • Cyclooxygenase 2
  • DNA / metabolism
  • Fibroblasts / metabolism
  • Histone Acetyltransferases
  • Humans
  • Isoenzymes / genetics*
  • Isoenzymes / metabolism*
  • Kinetics
  • Membrane Proteins
  • Phorbol Esters / metabolism
  • Plasmids / metabolism
  • Promoter Regions, Genetic*
  • Prostaglandin-Endoperoxide Synthases / genetics*
  • Prostaglandin-Endoperoxide Synthases / metabolism*
  • Protein Binding
  • Protein Isoforms
  • Time Factors
  • Transcription Factors
  • Transcription, Genetic
  • Transfection
  • p300-CBP Transcription Factors

Substances

  • CCAAT-Enhancer-Binding Proteins
  • Cell Cycle Proteins
  • Isoenzymes
  • Membrane Proteins
  • Phorbol Esters
  • Protein Isoforms
  • Transcription Factors
  • phorbol-12-myristate
  • DNA
  • Cyclooxygenase 2
  • PTGS2 protein, human
  • Prostaglandin-Endoperoxide Synthases
  • Acetyltransferases
  • Histone Acetyltransferases
  • p300-CBP Transcription Factors
  • p300-CBP-associated factor