title: Domains of estrogen receptor alpha (ERalpha) required for ERalpha/Sp1-mediated activation of GC-rich promoters by estrogens and antiestrogens in breast cancer cells.
abstract: Estrogen receptor alpha (ERalpha)/Sp1 activation of GC-rich gene promoters in breast cancer cells is dependent, in part, on activation function 1 (AF1) of ERalpha, and this study investigates contributions of the DNA binding domain (C) and AF2 (DEF) regions of ERalpha on activation of ERalpha/Sp1. 17Beta-estradiol (E2) and the antiestrogens 4-hydroxytamoxifen and ICI 182,780 induced reporter gene activity in MCF-7 and MDA-MB-231 cells cotransfected with human or mouse ERalpha (hERalpha or MOR), but not ERbeta and GC-rich constructs containing three tandem Sp1 binding sites (pSp13) or other E2-responsive GC-rich promoters. Estrogen and antiestrogen activation of hERalpha/Sp1 was dependent on overlapping and different regions of the C, D, E, and F domains of ERalpha. Antiestrogen-induced activation of hERalpha/Sp1 was lost using hERalpha mutants deleted in zinc finger 1 [amino acids (aa) 185-205], zinc finger 2 (aa 218-245), and the hinge/helix 1 (aa 265-330) domains. In contrast with antiestrogens, E2-dependent activation of hERalpha/Sp1 required the C-terminal F domain (aa 579-595), which contains a beta-strand structural motif. Moreover, in peptide competition experiments overexpression of a C-terminal (aa 575-595) F domain peptide specifically blocked E2-dependent activation of hERalpha/Sp1, suggesting that F domain interactions with nuclear cofactors are required for ERalpha/Sp1 action.
authors.affiliation: Department of Veterinary Physiology & Pharmacology, Texas A&M University, College Station, Texas 77843-4466, USA.
authors.forename: Kyounghyun
authors.initials: K
authors.lastname: Kim
authors.forename: Nguyen
authors.initials: N
authors.lastname: Thu
authors.forename: Brad
authors.initials: B
authors.lastname: Saville
authors.forename: Stephen
authors.initials: S
authors.lastname: Safe
mesh_terms: D001482:Base Composition; D001483:Base Sequence; D001665:Binding Sites; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics*; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens / Q000494:pharmacology*; D000077267:Fulvestrant; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011960:Receptors, Estrogen / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D013629:Tamoxifen / Q000031:analogs & derivatives* / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
chemical_list: D004965:Estrogen Antagonists; D020847:Estrogen Receptor Modulators; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens; D011960:Receptors, Estrogen; D016329:Sp1 Transcription Factor; D013629:Tamoxifen; C016601:afimoxifene; D000077267:Fulvestrant; D004958:Estradiol