title: GR SUMOylation and formation of an SUMO-SMRT/NCoR1-HDAC3 repressing complex is mandatory for GC-induced IR nGRE-mediated transrepression.
abstract: Unique among the nuclear receptor superfamily, the glucocorticoid (GC) receptor (GR) can exert three distinct transcriptional regulatory functions on binding of a single natural (cortisol in human and corticosterone in mice) and synthetic [e.g., dexamethasone (Dex)] hormone. The molecular mechanisms underlying GC-induced positive GC response element [(+)GRE]-mediated activation of transcription are partially understood. In contrast, these mechanisms remain elusive for GC-induced evolutionary conserved inverted repeated negative GC response element (IR nGRE)-mediated direct transrepression and for tethered indirect transrepression that is mediated by DNA-bound NF-κB/activator protein 1 (AP1)/STAT3 activators and instrumental in GC-induced anti-inflammatory activity. We demonstrate here that SUMOylation of lysine K293 (mouse K310) located within an evolutionary conserved sequence in the human GR N-terminal domain allows the formation of a GR-small ubiquitin-related modifiers (SUMOs)-NCoR1/SMRT-HDAC3 repressing complex mandatory for GC-induced IR nGRE-mediated direct repression in vitro, but does not affect transactivation. Importantly, these results were validated in vivo: in K310R mutant mice and in mice ablated selectively for nuclear receptor corepressor 1 (NCoR1)/silencing mediator for retinoid or thyroid-hormone receptors (SMRT) corepressors in skin keratinocytes, Dex-induced direct repression and the formation of repressing complexes on IR nGREs were impaired, whereas transactivation was unaffected. In mice selectively ablated for histone deacetylase 3 (HDAC3) in skin keratinocytes, GC-induced direct repression, but not bindings of GR and of corepressors NCoR1/SMRT, was abolished, indicating that HDAC3 is instrumental in IR nGRE-mediated repression. Moreover, we demonstrate that the binding of HDAC3 to IR nGREs in vivo is mediated through interaction with SMRT/NCoR1. We also show that the GR ligand binding domain (LBD) is not required for SMRT-mediated repression, which can be mediated by a LBD-truncated GR, whereas it is mandatory for NCoR1-mediated repression through an interaction with K579 in the LBD.
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR7104, INSERM U964, Illkirch 67404, France;
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Hua
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR7104, INSERM U964, Illkirch 67404, France;
authors.forename: Laetitia
authors.initials: L
authors.lastname: Paulen
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR7104, INSERM U964, Illkirch 67404, France; University of Strasbourg Institute for Advanced Study, Illkirch 67404, France; Collège de France, Illkirch 67404, France chambon@igbmc.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Chambon
mesh_terms: D000818:Animals; D005938:Glucocorticoids / Q000494:pharmacology*; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D056971:Nuclear Receptor Co-Repressor 1 / Q000235:genetics / Q000378:metabolism*; D056985:Nuclear Receptor Co-Repressor 2 / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D050796:STAT3 Transcription Factor / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism*; D058207:Sumoylation; D000099186:Histone Deacetylase 3
chemical_list: D005938:Glucocorticoids; D006655:Histone Deacetylases; D056971:Nuclear Receptor Co-Repressor 1; D056985:Nuclear Receptor Co-Repressor 2; D011965:Receptors, Glucocorticoid; D012097:Repressor Proteins; D050796:STAT3 Transcription Factor; D025841:Small Ubiquitin-Related Modifier Proteins; D000099186:Histone Deacetylase 3; C539128:Ncor1 protein, mouse; C539131:Ncor2 protein, mouse; C494087:Stat3 protein, mouse
keywords: GC-induced direct transrepression; IR nGRE; SUMOylation; glucocorticoid receptor