Yeast hormone response element assays detect and characterize GRIP1 coactivator-dependent activation of transcription by thyroid and retinoid nuclear receptors

摘要: The mouse glucocorticoid receptor-interacting protein (GRIP1) is a member of the ERAP160 family nuclear receptor (NR) coactivators (including SRC-1 and TIF2) which function as bridging proteins between ligand-activated NRs bound to cognate hormone-response elements (HREs) transcription initiation apparatus (TIA). Although these bind several NRs, studies overexpressing with in mammalian cells have not uniformly observed corresponding enhancement ligand-dependent transactivation. Here, we show that GRIP1 interacts vitro manner thyroid receptor, retinoic acid retinoid X receptor. Additionally, yeast (Saccharomyces cerevisiae) coactivator markedly increased ability full-length class II transactivate β-galactosidase reporter genes containing HREs. magnitude liganded NR homodimer was dependent upon subtype HRE configuration. For most configurations, homodimers were essentially unresponsive or very weakly active absence GRIP1, but dramatically restored NRs. exerted no significant effect on their ligands, it transactivation unliganded heterodimers. Whether heterodimer levels greater than determined by configuration copy number. Compared limitations two-hybrid coexpression systems, HRE-assay systems described this report facilitated both detection putative elucidation mechanisms transactivational enhancement.