title: Coactivation of estrogen receptor alpha (ER alpha)/Sp1 by vitamin D receptor interacting protein 150 (DRIP150).
abstract: Vitamin D receptor interacting protein (DRIP150) coactivates estrogen receptor alpha (ERalpha)-mediated transactivation in breast cancer cell lines transfected with a construct (pERE(3)) containing three estrogen responsive elements (EREs). In this study, we show that DRIP150 also coactivates ERalpha/Sp1-mediated transactivation in ZR-75, MCF-7, and MDA-MB-231 breast cancer cells transfected with a construct (pSp1(3)) containing three consensus GC-rich motifs. Studies on coactivation of wild-type and variant ERalpha/Sp1 by DRIP150 indicates that the DNA-binding domain and helix 12 in the ligand binding domain of ERalpha are required and the coactivation response is squelched by overexpressing an NR-box peptide that contains two LXXLL motifs from GRIP2. In contrast, coactivation of ERalpha/Sp1 by wild-type and mutant DRIP150 expression plasmids show that coactivation of ERalpha/Sp1 by DRIP150 is independent of the NR-boxes. Deletion analysis of DRIP150 demonstrates that coactivation requires an alpha-helical NIFSEVRVYN (amino acids 795-804) motif within 23 amino acid sequence (789-811) in the central region of DRIP150 and similar results were obtained for coactivation of ERalpha by DRIP150. Thus, although different domains of ERalpha are required for hormone-dependent activation of ERalpha and ERalpha/Sp1, coactivation of these transcription factors by DRIP150 requires the alpha-helical amino acids 795-804. This is the first report of a coactivator that enhances ERalpha/Sp1-mediated transactivation in breast cancer cells.
authors.affiliation: Department of Veterinary Physiology and Pharmacology, Texas A&M University College Station, TX 77843-4466, USA.
authors.forename: Jeongeun
authors.initials: J
authors.lastname: Lee
authors.forename: Stephen
authors.initials: S
authors.lastname: Safe
mesh_terms: D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D003067:Coenzymes / Q000502:physiology; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D056892:Mediator Complex; D008969:Molecular Sequence Data; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D015534:Trans-Activators / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*
chemical_list: D003067:Coenzymes; D047628:Estrogen Receptor alpha; C492160:MED14 protein, human; D056892:Mediator Complex; D016329:Sp1 Transcription Factor; D015534:Trans-Activators