title: Transcriptional activation of transforming growth factor alpha by estradiol: requirement for both a GC-rich site and an estrogen response element half-site.
abstract: 17beta-Estradiol (E2) induces transforming growth factor alpha (TGFalpha) gene expression in MCF-7 cells and previous studies have identified a 53 bp (-252 to -200) sequence containing two imperfect estrogen responsive elements (EREs) that contribute to E2 responsiveness. Deletion analysis of the TGFalpha gene promoter in this study identified a second upstream region of the promoter (-623 to -549) that is also E2 responsive. This sequence contains three GC-rich sites and an imperfect ERE half-site, and the specific cis-elements and trans-acting factors were determined by promoter analysis in transient transfection experiments, gel mobility shift assays and in vitro DNA footprinting. The results are consistent with an estrogen receptor alpha (ERalpha)/Sp1 complex interacting with an Sp1(N)(30) ERE half-site ((1/2)) motif in which both ERalpha and Sp1 bind promoter DNA. The ER/Sp1-DNA complex is formed using nuclear extracts from MCF-7 cells but not with recombinant human ERalpha or Sp1 proteins, suggesting that other nuclear factor(s) are required for complex stabilization. The E2-responsive Sp1(N)(x)ERE(1/2) motif identified in the TGFalpha gene promoter has also been characterized in the cathepsin D and heat shock protein 27 gene promoters; however, in the latter two promoters the numbers of intervening nucleotides are 23 and 10 respectively.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: C
authors.initials: C
authors.lastname: Vyhlidal
authors.forename: I
authors.initials: I
authors.lastname: Samudio
authors.forename: M P
authors.initials: MP
authors.lastname: Kladde
authors.forename: S
authors.initials: S
authors.lastname: Safe
mesh_terms: D000818:Animals; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology; D018983:DNA Footprinting; D004330:Drosophila; D004958:Estradiol / Q000502:physiology*; D020862:GC Rich Sequence; D006801:Humans; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion; D015533:Transcriptional Activation; D016211:Transforming Growth Factor alpha / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: D009838:Oligodeoxyribonucleotides; D016211:Transforming Growth Factor alpha; D004958:Estradiol