Identification of a retinoid/chicken ovalbumin upstream promoter transcription factor response element in the human retinoid X receptor gamma2 gene promoter.
To investigate the mechanisms involved in the transcriptional control of retinoid X receptor (RXR) gene expression, the 5'-flanking region of the human RXRgamma2 isoform was characterized. An imperfect hexamer repeat (gamma retinoid X response element; gammaRXRE) with a single nucleotide spacer (GGTTGAaAGGTCA) was identified immediately upstream of the RXRgamma2 gene transcription start site. Cotransfection studies in CV-1 cells with expression vectors for the retinoid receptors RXRalpha and retinoic acid receptor beta (RARbeta) demonstrated that the gammaRXRE confers retinoid-mediated transcriptional activation with preferential activation by RXR in the presence of its cognate ligand, 9-cis-retinoic acid (RA). Electrophoretic mobility shift assays demonstrated that RXR homodimer binding to gammaRXRE is markedly enhanced by 9-cis-RA, whereas RAR.RXR heterodimer binding is ligand-independent. DNA binding studies and cell cotransfection experiments also demonstrated that the nuclear receptor, chicken ovalbumin upstream promoter transcription factor (COUP-TF), repressed transcription via the gammaRXRE. Cotransfection experiments revealed that COUP-TF and RXRalpha compete at the gammaRXRE to modulate transcription bidirectionally over a wide range. These results demonstrate that the human RXRgamma2 gene promoter contains a novel imperfect repeat element capable of mediating RXR-dependent transcriptional autoactivation and COUP-TF-dependent repression.
Barger
P M
PM
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Kelly
D P
DP
D000077556:Alitretinoin; D000818:Animals; D001483:Base Sequence; D051838:COUP Transcription Factor I; D002460:Cell Line; D002645:Chickens; D017931:DNA Primers; D004275:DNA, Ribosomal / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005091:Exons; D006801:Humans; D009206:Myocardium / Q000378:metabolism; D010047:Ovalbumin / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D047488:Retinoid X Receptors; D016385:TATA Box; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology*
D051838:COUP Transcription Factor I; D017931:DNA Primers; D004275:DNA, Ribosomal; D004268:DNA-Binding Proteins; C497589:NR2F1 protein, human; D011965:Receptors, Glucocorticoid; D018168:Receptors, Retinoic Acid; D011994:Recombinant Proteins; D047488:Retinoid X Receptors; D014157:Transcription Factors; D000077556:Alitretinoin; D014212:Tretinoin; D010047:Ovalbumin