title: COUP-TFI and COUP-TFII regulate expression of the NHE through a nuclear hormone responsive element with enhancer activity.
abstract: The chicken ovalbumin upstream promoter-transcription factors (COUP-TFs) are orphan receptors involved in regulation of embryonic development and neuronal cell fate determination. We identified a target of COUP-TF involved in cell proliferation and cell differentiation. Using reporter assays, footprint analysis, and electrophoretic mobility shift assays, we showed that a nuclear hormone-responsive element located at -841/-800 nt of the mouse Na(+)/H(+) exchanger (NHE) promoter binds COUP-TF with enhancer activity. Mutation at -829/-824 nt (and secondarily at -837/-833) prevents COUP binding and activation of the NHE promoter. In vivo expression of COUP isoforms in NIH 3T3 or CV1 cells transactivates from the nuclear hormone-responsive element and from the entire NHE1 promoter. Transactivation is greater for COUP-TFII, is increased for either COUP isoform by the presence of high serum concentrations, and is greatly reduced by mutations preventing COUP binding. In vivo COUP expression in NIH 3T3 cells results in increased synthesis of NHE. Expression of COUP-TFII induced by either retinoic acid or dimethyl sulfoxide in differentiating P19 cells increases NHE expression. The results show that COUP-TF regulates expression of the NHE and provide a mechanism that may be important in physiological and pathological situations linked to its upregulation.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Fernandez-Rachubinski
authors.forename: L
authors.initials: L
authors.lastname: Fliegel
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D051838:COUP Transcription Factor I; D051837:COUP Transcription Factor II; D051836:COUP Transcription Factors; D002454:Cell Differentiation; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003470:Culture Media / Q000494:pharmacology; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004742:Enhancer Elements, Genetic; D017930:Genes, Reporter; D006801:Humans; D008099:Liver / Q000378:metabolism; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011987:Receptors, Steroid; D020218:Response Elements; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D051838:COUP Transcription Factor I; D051837:COUP Transcription Factor II; D051836:COUP Transcription Factors; D003470:Culture Media; D004268:DNA-Binding Proteins; D004121:Dimethyl Sulfoxide; D020033:Protein Isoforms; D012333:RNA, Messenger; D011987:Receptors, Steroid; D017923:Sodium-Hydrogen Exchangers; D014157:Transcription Factors; D014212:Tretinoin; C497589:NR2F1 protein, human; C497590:Nr2f1 protein, mouse; C497591:Nr2f1 protein, rat; C497587:Nr2f2 protein, mouse; C497588:Nr2f2 protein, rat; C095569:NR2F2 protein, human