Functional and physical interactions between the estrogen receptor Sp1 and nuclear aryl hydrocarbon receptor complexes

Nucleic Acids Res. 1998 Jun 15;26(12):3044-52. doi: 10.1093/nar/26.12.3044.

Abstract

17beta-Estradiol (E2) induces cathepsin D gene expression in MCF-7 human breast cancer cells and previous analyses of the proximal promoter region of this gene identified two functional enhancer sequences; namely an Sp1(N)23estrogen-responsive element (ERE) half-site (-199 to -165) and an imperfect palindromic ERE (-119 to -107). A third region of the cathepsin D gene promoter (CD/L, -145 to -119) was also E2 responsive in transient transfection assays. A GC-rich sequence which contains two overlapping Sp1 binding sites (-145 to -135) was responsible for ER-mediated transactivation and required formation of an ER/Sp1 complex in which only the Sp1 protein bound DNA. E2 responsiveness of the CD/L sequence was also dependent on an adjacent overlapping GCGTG motif corresponding to the dioxin-responsive element (DRE) core binding sequence, which is the cognate response element for the heterodimeric aryl hydrocarbon receptor (AhR)/AhR nuclear translocator (ARNT) transcription factor complex. The results show that ER-mediated transactivation of CD/L was associated with the Sp1(N)2-4DRE (core) motif and involved formation of a multiprotein ER/Sp1-AhR/ARNT complex. These results illustrate a unique example of an endogenous role for AhR/ARNT in the absence of added AhR agonist and indicate that the cathepsin D gene proximal promoter region contains at least three different functional motifs associated with ER-mediated transactivation.

Publication types

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

MeSH terms

  • Aryl Hydrocarbon Receptor Nuclear Translocator
  • Benzoflavones / pharmacology
  • Binding, Competitive
  • Breast Neoplasms
  • Cathepsin D / genetics*
  • Cell Extracts
  • DNA / metabolism*
  • DNA, Antisense
  • DNA-Binding Proteins*
  • Enhancer Elements, Genetic / genetics
  • Estradiol / pharmacology
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Promoter Regions, Genetic / genetics
  • Protein Binding
  • Receptors, Aryl Hydrocarbon / antagonists & inhibitors
  • Receptors, Aryl Hydrocarbon / genetics
  • Receptors, Aryl Hydrocarbon / metabolism*
  • Receptors, Estrogen / genetics
  • Receptors, Estrogen / metabolism*
  • Recombinant Fusion Proteins
  • Sp1 Transcription Factor / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcriptional Activation / physiology
  • Transfection
  • Tumor Cells, Cultured

Substances

  • ARNT protein, human
  • Benzoflavones
  • Cell Extracts
  • DNA, Antisense
  • DNA-Binding Proteins
  • Receptors, Aryl Hydrocarbon
  • Receptors, Estrogen
  • Recombinant Fusion Proteins
  • Sp1 Transcription Factor
  • Transcription Factors
  • Aryl Hydrocarbon Receptor Nuclear Translocator
  • Estradiol
  • alpha-naphthoflavone
  • DNA
  • Cathepsin D