Crystal structure of RARalpha ligand binding domain in complex with the inverse agonist BMS493 and a corepressor fragment
[RARA_HUMAN] Note=Chromosomal aberrations involving RARA are commonly found in acute promyelocytic leukemia. Translocation t(11;17)(q32;q21) with ZBTB16/PLZF; translocation t(15;17)(q21;q21) with PML; translocation t(5;17)(q32;q11) with NPM. The PML-RARA oncoprotein requires both the PML ring structure and coiled-coil domain for both interaction with UBE2I, nuclear microspeckle location and sumoylation. In addition, the coiled-coil domain functions in blocking RA-mediated transactivation and cell differentiation.
[RARA_HUMAN] Receptor for retinoic acid. Retinoic acid receptors bind as heterodimers to their target response elements in response to their ligands, all-trans or 9-cis retinoic acid, and regulate gene expression in various biological processes. The RXR/RAR heterodimers bind to the retinoic acid response elements (RARE) composed of tandem 5'-AGGTCA-3' sites known as DR1-DR5. In the absence of ligand, the RXR-RAR heterodimers associate with a multiprotein complex containing transcription corepressors that induce histone acetylation, chromatin condensation and transcriptional suppression. On ligand binding, the corepressors dissociate from the receptors and associate with the coactivators leading to transcriptional activation. RARA plays an essential role in the regulation of retinoic acid-induced germ cell development during spermatogenesis. Has a role in the survival of early spermatocytes at the beginning prophase of meiosis. In Sertoli cells, may promote the survival and development of early meiotic prophase spermatocytes. In concert with RARG, required for skeletal growth, matrix homeostasis and growth plate function (By similarity). Regulates expression of target genes in a ligand-dependent manner by recruiting chromatin complexes containing MLL5. Mediates retinoic acid-induced granulopoiesis.    [NCOR1_HUMAN] Mediates transcriptional repression by certain nuclear receptors. Part of a complex which promotes histone deacetylation and the formation of repressive chromatin structures which may impede the access of basal transcription factors.
Publication Abstract from PubMed
In the absence of ligand, some nuclear receptors, including retinoic acid receptor (RAR), act as transcriptional repressors by recruiting corepressor complexes to target genes. This constitutive repression is crucial in metazoan reproduction, development and homeostasis. However, its specific molecular determinants had remained obscure. Using structural, biochemical and cell-based assays, we show that the basal repressive activity of RAR is conferred by an extended beta-strand that forms an antiparallel beta-sheet with specific corepressor residues. Agonist binding induces a beta-strand-to-alpha-helix transition that allows for helix H11 formation, which in turn provokes corepressor release, repositioning of helix H12 and coactivator recruitment. Several lines of evidence suggest that this structural switch could be implicated in the intrinsic repressor function of other nuclear receptors. Finally, we report on the molecular mechanism by which inverse agonists strengthen corepressor interaction and enhance gene silencing by RAR.
A unique secondary-structure switch controls constitutive gene repression by retinoic acid receptor.,le Maire A, Teyssier C, Erb C, Grimaldi M, Alvarez S, de Lera AR, Balaguer P, Gronemeyer H, Royer CA, Germain P, Bourguet W Nat Struct Mol Biol. 2010 Jul;17(7):801-7. Epub 2010 Jun 13. PMID:20543827
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.