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Chicken ovalbumin upstream promoter-transcription factor interacts with estrogen receptor, binds to estrogen response elements and half-sites, and inhibits estrogen-induced gene expression.

Chicken ovalbumin upstream promoter-transcription factor (COUP-TF) was identified as a low abundance protein in bovine uterus that co-purified with estrogen receptor (ER) in a ligand-independent manner and was separated from the ER by its lower retention on estrogen response element (ERE)-Sepharose. In gel mobility shift assays, COUP-TF bound as an apparent dimer to ERE and ERE half-sites. COUP-TF bound to an ERE half-site with high affinity, Kd = 1.24 nM. In contrast, ER did not bind a single ERE half-site. None of the class II nuclear receptors analyzed, i.e. retinoic acid receptor, retinoid X receptor, thyroid receptor, peroxisome proliferator-activated receptor, or vitamin D receptor, were constituents of the COUP-TF.DNA binding complex detected in gel mobility shift assays. Direct interaction of COUP-TF with ER was indicated by GST "pull-down" and co-immunoprecipitation assays. The nature of the ER ligand influenced COUP-TF-ERE half-site binding. When ER was liganded by the antiestrogen 4-hydroxytamoxifen (4-OHT), COUP-TF-half-site interaction decreased. Conversely, COUP-TF transcribed and translated in vitro enhanced the ERE binding of purified estradiol (E2)-liganded ER but not 4-OHT-liganded ER. Co-transfection of ER-expressing MCF-7 human breast cancer cells with an expression vector for COUP-TFI resulted in a dose-dependent inhibition of E2-induced expression of a luciferase reporter gene under the control of three tandem copies of EREc38. The ability of COUP-TF to bind specifically to EREs and half-sites, to interact with ER, and to inhibit E2-induced gene expression suggests COUP-TF regulates ER action by both direct DNA binding competition and through protein-protein interactions.

Pubmed ID: 9395481


  • Klinge CM
  • Silver BF
  • Driscoll MD
  • Sathya G
  • Bambara RA
  • Hilf R


The Journal of biological chemistry

Publication Data

December 12, 1997

Associated Grants

  • Agency: NIEHS NIH HHS, Id: 1P20 ES06832-12
  • Agency: NICHD NIH HHS, Id: HD24459

Mesh Terms

  • Animals
  • Antibodies, Monoclonal
  • COUP Transcription Factor I
  • Cattle
  • Chickens
  • Consensus Sequence
  • DNA
  • DNA-Binding Proteins
  • Estrogens
  • Gene Expression
  • Genes, Reporter
  • Humans
  • Kinetics
  • Ovalbumin
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Estrogen
  • Receptors, Glucocorticoid
  • Recombinant Proteins
  • Transcription Factors
  • Transcriptional Activation
  • Tumor Cells, Cultured
  • Ultraviolet Rays