title: Corepressor binding to progesterone and glucocorticoid receptors involves the activation function-1 domain and is inhibited by molybdate.
abstract: Corepressors are known to interact via their receptor interaction domains (RIDs) with the ligand binding domain in the carboxyl terminal half of steroid/nuclear receptors. We now report that a portion of the activation function-1 domain of glucocorticoid receptors (GRs) and progesterone receptors (PRs), which is the major transactivation sequence, is necessary but not sufficient for corepressor [nuclear receptor corepressor (NCoR) and silencing mediator of retinoid and thyroid hormone receptor (SMRT)] RID binding to GRs and PRs in both mammalian two-hybrid and coimmunoprecipitation assays. Importantly, these two receptor sequences are functionally interchangeable in the context of GR for transactivation, corepressor binding, and corepressor modulatory activity assays. This suggests that corepressors may act in part by physically blocking portions of receptor activation function-1 domains. However, differences exist in corepressor binding to GRs and PRs. The C-terminal domain of PRs has a higher affinity for corepressor than that of GRs. The ability of some segments of the coactivator TIF2 to competitively inhibit corepressor binding to receptors is different for GRs and PRs. With each receptor, the cell-free binding of corepressors to ligand-free receptor is prevented by sodium molybdate, which is a well-known inhibitor of receptor activation to the DNA-binding state. This suggests that receptor activation precedes binding to corepressors. Collectively, these results indicate that corepressor binding to GRs and PRs involve both N- and C-terminal sequences of activated receptors but differ in ways that may contribute to the unique biological responses of each receptor in intact cells.
authors.affiliation: Steroid Hormones Section, National Institute of Diabetes and Digestive and Kidney Diseases/Laboratory of Molecular and Cellular Biology, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Dongqing
authors.initials: D
authors.lastname: Wang
authors.forename: S Stoney
authors.initials: SS
authors.lastname: Simons
mesh_terms: D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001681:Biological Assay; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D002474:Cell-Free System; D004247:DNA / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism; D017353:Gene Deletion; D017405:Herpes Simplex Virus Protein Vmw65 / Q000378:metabolism; D047468:Immunoprecipitation; D008024:Ligands; D008156:Luciferases / Q000378:metabolism; D008954:Models, Biological; D008982:Molybdenum / Q000378:metabolism* / Q000494:pharmacology; D009687:Nuclear Proteins / Q000378:metabolism; D056971:Nuclear Receptor Co-Repressor 1; D056985:Nuclear Receptor Co-Repressor 2; D010957:Plasmids / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D004268:DNA-Binding Proteins; D017405:Herpes Simplex Virus Protein Vmw65; D008024:Ligands; D009687:Nuclear Proteins; D056971:Nuclear Receptor Co-Repressor 1; D056985:Nuclear Receptor Co-Repressor 2; D011965:Receptors, Glucocorticoid; D011980:Receptors, Progesterone; D012097:Repressor Proteins; C044659:molybdate; D011374:Progesterone; D008982:Molybdenum; D004247:DNA; D008156:Luciferases