Long-range activation of GREB1 by estrogen receptor via three distal consensus estrogen-responsive elements in breast cancer cells.
The estrogen receptor (ER) binds to estrogen-responsive elements (EREs) to activate gene transcription. The best characterized EREs are located in proximal gene promoters, but recent data indicate that only a minority of ER binding sites lie within proximal promoter regions. GREB1 (gene regulated by estrogen in breast cancer 1) is an ER target gene that regulates estrogen-induced proliferation in breast cancer cells. We identified three consensus EREs, located at -21.2, -9.5, and -1.6 kb upstream of the closest GREB1a transcription start site that appear to mediate long-range GREB1 gene activation by ER. All three ERE sites nucleate ER, steroid receptor coactivator-3 (SRC-3), and RNA polymerase II (Pol II) and undergo histone acetylation in response to estradiol. Estrogen-stimulated ER binding at all three EREs was cyclic and synchronous. SRC-3 and Pol II recruitment to all three EREs was activated by estrogen but not tamoxifen. In contrast, estrogen stimulated only Pol II and not ER or SRC-3 recruitment to the GREB1 core promoter regions. Long-range histone acetylation, centered on the three ERE motifs and the GREB1 core promoters, was observed in response to estrogen but not to tamoxifen. These data suggest that estrogen-stimulated GREB1 transcription may involve coordinated ER binding to all three distal consensus ERE motifs. Long-range activation by ER acting at multiple EREs may be more common than previously appreciated.
Sun
Jun
J
Braman Family Breast Cancer Institute, 1580 NW 10 Avenue (M-877), University of Miami, Miami, Florida 33136, USA. jsun@med.miami.edu
Nawaz
Zafar
Z
Slingerland
Joyce M
JM
D020816:Amino Acid Motifs; D001483:Base Sequence; D001943:Breast Neoplasms / Q000378:metabolism*; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D004958:Estradiol / Q000378:metabolism; D004967:Estrogens / Q000378:metabolism; D051548:Histone Acetyltransferases / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000378:metabolism* / Q000502:physiology*; D056921:Nuclear Receptor Coactivator 3; D011401:Promoter Regions, Genetic; D011960:Receptors, Estrogen / Q000378:metabolism; D013629:Tamoxifen / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic
D004967:Estrogens; C416830:GREB1 protein, human; D009363:Neoplasm Proteins; D011960:Receptors, Estrogen; D015534:Trans-Activators; D013629:Tamoxifen; D004958:Estradiol; D051548:Histone Acetyltransferases; C538866:NCOA3 protein, human; D056921:Nuclear Receptor Coactivator 3