Domains of estrogen receptor alpha (ERalpha) required for ERalpha/Sp1-mediated activation of GC-rich promoters by estrogens and antiestrogens in breast cancer cells

Mol Endocrinol. 2003 May;17(5):804-17. doi: 10.1210/me.2002-0406. Epub 2003 Feb 6.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Composition
  • Base Sequence
  • Binding Sites
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / genetics*
  • Estradiol / analogs & derivatives*
  • Estradiol / pharmacology
  • Estrogen Antagonists / pharmacology
  • Estrogen Receptor Modulators / pharmacology*
  • Estrogen Receptor alpha
  • Estrogen Receptor beta
  • Estrogens / pharmacology*
  • Fulvestrant
  • Gene Expression Regulation
  • Molecular Sequence Data
  • Point Mutation
  • Promoter Regions, Genetic*
  • Protein Structure, Tertiary
  • Receptors, Estrogen / drug effects
  • Receptors, Estrogen / genetics
  • Receptors, Estrogen / metabolism*
  • Sp1 Transcription Factor / genetics
  • Sp1 Transcription Factor / metabolism*
  • Tamoxifen / analogs & derivatives*
  • Tamoxifen / pharmacology
  • Tumor Cells, Cultured
  • Zinc Fingers


  • Estrogen Antagonists
  • Estrogen Receptor Modulators
  • Estrogen Receptor alpha
  • Estrogen Receptor beta
  • Estrogens
  • Receptors, Estrogen
  • Sp1 Transcription Factor
  • Tamoxifen
  • afimoxifene
  • Fulvestrant
  • Estradiol