Genomic structure of the promoters of the human estrogen receptor-alpha gene demonstrate changes in chromatin structure induced by AP2gamma.
Expression of human estrogen receptor-alpha (ERalpha) involves the activity from several promoters that give rise to alternate untranslated 5' exons. However, the genomic locations of the alternate 5' exons have not been reported previously. We have developed a contig map of the human ERalpha gene that includes all of the known alternate 5' exons. By using S1 nuclease and 5'- rapid amplification of cDNA ends, the cap sites for the alternate ERalpha transcripts E and H were identified. DNase I-hypersensitive sites specific to ERalpha-positive cells were associated with each of the cap sites. A DNase I-hypersensitive site, HS1, was localized to binding sites for AP2 in the untranslated region of exon 1 and was invariably present in the chromatin structure of ERalpha-positive cells. Overexpression of AP2gamma in human mammary epithelial cells generated the HS1-hypersensitive site. The ERalpha promoter was induced by AP2gamma in mammary epithelial cells, and trans-activation was dependent upon the region of the promoter containing the HS1 site. These results demonstrate that AP2gamma trans-activates the ERalpha gene in hormone-responsive tumors by inducing changes in the chromatin structure of the ERalpha promoter. These data are further evidence for a critical role for AP2 in the oncogenesis of hormone-responsive breast cancers.
Department of Surgery, Stanford University School of Medicine, Stanford, California 94305-3229, USA.
E R
ER
Schuur
L A
LA
McPherson
G P
GP
Yang
R J
RJ
Weigel
D017398:Alternative Splicing; D001483:Base Sequence; D002460:Cell Line; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism*; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D047628:Estrogen Receptor alpha; D005091:Exons; D006801:Humans; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D011960:Receptors, Estrogen / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D002843:Chromatin; D017931:DNA Primers; D004268:DNA-Binding Proteins; D047628:Estrogen Receptor alpha; D011960:Receptors, Estrogen; D011994:Recombinant Proteins; D050656:Transcription Factor AP-2; D014157:Transcription Factors