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Woo ARE, Sze SK, Chung HH, Lin VCL. Delineation of critical amino acids in activation function 1 of progesterone receptor for recruitment of transcription coregulators. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:522-533. [DOI: 10.1016/j.bbagrm.2019.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 01/15/2019] [Accepted: 01/30/2019] [Indexed: 12/17/2022]
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2
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Rantalainen M, Bjerrum JT, Olsen J, Nielsen OH, Wang Y. Integrative Transcriptomic and Metabonomic Molecular Profiling of Colonic Mucosal Biopsies Indicates a Unique Molecular Phenotype for Ulcerative Colitis. J Proteome Res 2014; 14:479-90. [DOI: 10.1021/pr500699h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Mattias Rantalainen
- Department
of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-17177 Stockholm, Sweden
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and
Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Jacob Tveiten Bjerrum
- Department
of Cellular and Molecular Medicine, The Panum Institute, University of Copenhagen, DK-2200, Copenhagen, Denmark
- Department
of Gastroenterology, Medical Section, Herlev Hospital, University of Copenhagen, DK-2730 Herlev, Denmark
| | - Jørgen Olsen
- Department
of Cellular and Molecular Medicine, The Panum Institute, University of Copenhagen, DK-2200, Copenhagen, Denmark
| | - Ole Haagen Nielsen
- Department
of Gastroenterology, Medical Section, Herlev Hospital, University of Copenhagen, DK-2730 Herlev, Denmark
| | - Yulan Wang
- Key
Laboratory of Magnetic Resonance in Biological Systems, State Key
Laboratory of Magnetic Resonance and Atomic and Molecular Physics,
Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and
Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
- Collaborative
Innovation Center for the Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou 310058, P. R. China
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3
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Blackford JA, Brimacombe KR, Dougherty EJ, Pradhan M, Shen M, Li Z, Auld DS, Chow CC, Austin CP, Simons SS. Research resource: modulators of glucocorticoid receptor activity identified by a new high-throughput screening assay. Mol Endocrinol 2014; 28:1194-206. [PMID: 24850414 DOI: 10.1210/me.2014-1069] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Glucocorticoid steroids affect almost every type of tissue and thus are widely used to treat a variety of human pathological conditions. However, the severity of numerous side effects limits the frequency and duration of glucocorticoid treatments. Of the numerous approaches to control off-target responses to glucocorticoids, small molecules and pharmaceuticals offer several advantages. Here we describe a new, extended high-throughput screen in intact cells to identify small molecule modulators of dexamethasone-induced glucocorticoid receptor (GR) transcriptional activity. The novelty of this assay is that it monitors changes in both GR maximal activity (A(max)) and EC(50) (the position of the dexamethasone dose-response curve). Upon screening 1280 chemicals, 10 with the greatest changes in the absolute value of A(max) or EC(50) were selected for further examination. Qualitatively identical behaviors for 60% to 90% of the chemicals were observed in a completely different system, suggesting that other systems will be similarly affected by these chemicals. Additional analysis of the 10 chemicals in a recently described competition assay determined their kinetically defined mechanism and site of action. Some chemicals had similar mechanisms of action despite divergent effects on the level of the GR-induced product. These combined assays offer a straightforward method of identifying numerous new pharmaceuticals that can alter GR transactivation in ways that could be clinically useful.
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Affiliation(s)
- John A Blackford
- Steroid Hormones Section (J.A.B., E.J.D., M.P., S.S.S.), Laboratory of Endocrinology and Receptor Biology, and Laboratory of Biological Modeling (C.C.C.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892; and National Center for Advancing Translational Sciences (K.R.B., M.S., Z.L., D.S.A., C.P.A.), National Institutes of Health, Rockville, Maryland 20892
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4
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Chung HH, Sze SK, Woo ARE, Sun Y, Sim KH, Dong XM, Lin VCL. Lysine methylation of progesterone receptor at activation function 1 regulates both ligand-independent activity and ligand sensitivity of the receptor. J Biol Chem 2014; 289:5704-22. [PMID: 24415758 DOI: 10.1074/jbc.m113.522839] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Progesterone receptor (PR) exists in two isoforms, PRA and PRB, and both contain activation functions AF-1 and AF-2. It is believed that AF-1 is primarily responsible for the ligand-independent activity, whereas AF-2 mediates ligand-dependent PR activation. Although more than a dozen post-translational modifications of PR have been reported, no post-translational modification on AF-1 or AF-2 has been reported. Using LC-MS/MS-based proteomic analysis, this study revealed AF-1 monomethylation at Lys-464. Mutational analysis revealed the remarkable importance of Lys-464 in regulating PR activity. Single point mutation K464Q or K464A led to ligand-independent PR gel upshift similar to the ligand-induced gel upshift. This upshift was associated with increases in both ligand-dependent and ligand-independent PR phosphorylation and PR activity due to the hyperactivation of AF-1. In contrast, mutation of Lys-464 to the bulkier phenylalanine to mimic the effect of methylation caused a drastic decrease in PR activity. Importantly, PR-K464Q also showed heightened ligand sensitivity, and this was associated with increases in its functional interaction with transcription co-regulators NCoR1 and SRC-1. These results suggest that monomethylation of PR at Lys-464 probably has a repressive effect on AF-1 activity and ligand sensitivity.
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Affiliation(s)
- Hwa Hwa Chung
- From the School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
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5
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Simons SS, Edwards DP, Kumar R. Minireview: dynamic structures of nuclear hormone receptors: new promises and challenges. Mol Endocrinol 2013; 28:173-82. [PMID: 24284822 DOI: 10.1210/me.2013-1334] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Therapeutic targeting of nuclear receptors (NRs) is presently restricted due to 2 constraints: 1) a limited knowledge of the structural dynamics of intact receptor when complexed to DNA and coregulatory proteins; and 2) the inability to more selectively modulate NR actions at specific organ/gene targets. A major obstacle has been the current lack of understanding about the function and structure of the intrinsically disordered N-terminal domain that contains a major regulatory transcriptional activation function (AF1). Current studies of both mechanism of action and small molecule-selective receptor modulators for clinical uses target the structured pocket of the ligand-binding domain to modulate coregulatory protein interactions with the other activation function AF2. However, these approaches overlook AF1 activity. Recent studies have shown that highly flexible intrinsically disordered regions of transcription factors, including that of the N-terminal domain AF1 of NRs, not only are critical for several aspects of NR action but also can be exploited as drug targets, thereby opening unique opportunities for endocrine-based therapies. In this review article, we discuss the role of structural flexibilities in the allosteric modulation of NR activity and future perspectives for therapeutic interventions.
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Affiliation(s)
- S Stoney Simons
- Steroid Hormones Section (S.S.S.), Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892; Departments of Molecular & Cellular Biology and Pathology & Immunology (D.P.E.), Baylor College of Medicine, Houston, Texas 77030; and Department of Basic Sciences (R.K.), The Commonwealth Medical College, Scranton, Pennsylvania 18510
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6
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Kumar R, Moure CM, Khan SH, Callaway C, Grimm SL, Goswami D, Griffin PR, Edwards DP. Regulation of the structurally dynamic N-terminal domain of progesterone receptor by protein-induced folding. J Biol Chem 2013; 288:30285-30299. [PMID: 23995840 DOI: 10.1074/jbc.m113.491787] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The N-terminal domain (NTD) of steroid receptors harbors a transcriptional activation function (AF1) that is composed of an intrinsically disordered polypeptide. We examined the interaction of the TATA-binding protein (TBP) with the NTD of the progesterone receptor (PR) and its ability to regulate AF1 activity through coupled folding and binding. As assessed by solution phase biophysical methods, the isolated NTD of PR contains a large content of random coil, and it is capable of adopting secondary α-helical structure and more stable tertiary folding either in the presence of the natural osmolyte trimethylamine-N-oxide or through a direct interaction with TBP. Hydrogen-deuterium exchange coupled with mass spectrometry confirmed the highly dynamic intrinsically disordered property of the NTD within the context of full-length PR. Deletion mapping and point mutagenesis defined a region of the NTD (amino acids 350-428) required for structural folding in response to TBP interaction. Overexpression of TBP in cells enhanced transcriptional activity mediated by the PR NTD, and deletion mutations showed that a region (amino acids 327-428), similar to that required for TBP-induced folding, was required for functional response. TBP also increased steroid receptor co-activator 1 (SRC-1) interaction with the PR NTD and cooperated with SRC-1 to stimulate NTD-dependent transcriptional activity. These data suggest that TBP can mediate structural reorganization of the NTD to facilitate the binding of co-activators required for maximal transcriptional activation.
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Affiliation(s)
- Raj Kumar
- the Department of Basic Sciences, Commonwealth Medical College, Scranton, Pennsylvania 18509
| | - Carmen M Moure
- From the Departments of Molecular and Cellular Biology and
| | - Shagufta H Khan
- the Department of Basic Sciences, Commonwealth Medical College, Scranton, Pennsylvania 18509
| | | | - Sandra L Grimm
- From the Departments of Molecular and Cellular Biology and
| | - Devrishi Goswami
- the Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, and
| | - Patrick R Griffin
- the Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, and
| | - Dean P Edwards
- From the Departments of Molecular and Cellular Biology and; Pathology and Immunology, Baylor College of Medicine, Houston, Texas 77030,.
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7
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Zhang Z, Sun Y, Cho YW, Chow CC, Simons SS. PA1 protein, a new competitive decelerator acting at more than one step to impede glucocorticoid receptor-mediated transactivation. J Biol Chem 2012; 288:42-58. [PMID: 23161582 DOI: 10.1074/jbc.m112.427740] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Numerous cofactors modulate the gene regulatory activity of glucocorticoid receptors (GRs) by affecting one or more of the following three major transcriptional properties: the maximal activity of agonists (A(max)), the potency of agonists (EC(50)), and the partial agonist activity of antisteroids (PAA). Here, we report that the recently described nuclear protein, Pax2 transactivation domain interaction protein (PTIP)-associated protein 1 (PA1), is a new inhibitor of GR transactivation. PA1 suppresses A(max), increases the EC(50), and reduces the PAA of an exogenous reporter gene in a manner that is independent of associated PTIP. PA1 is fully active with, and strongly binds to, the C-terminal half of GR. PA1 reverses the effects of the coactivator TIF2 on GR-mediated gene induction but is unable to augment the actions of the corepressor SMRT. Analysis of competition assays between PA1 and TIF2 with an exogenous reporter indicates that the kinetic definition of PA1 action is a competitive decelerator at two sites upstream from where TIF2 acts. With the endogenous genes IGFBP1 and IP6K3, PA1 also represses GR induction, increases the EC(50), and decreases the PAA. ChIP and re-ChIP experiments indicate that PA1 accomplishes this inhibition of the two genes via different mechanisms as follows: PA1 appears to increase GR dissociation from and reduce GR transactivation at the IGFBP1 promoter regions but blocks GR binding to the IP6K3 promoter. We conclude that PA1 is a new competitive decelerator of GR transactivation and can act at more than one molecularly defined step in a manner that depends upon the specific gene.
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Affiliation(s)
- Zhenhuan Zhang
- Steroid Hormones Section, National Institutes of Health, Bethesda, Maryland 20892, USA
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8
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Khan SH, Awasthi S, Guo C, Goswami D, Ling J, Griffin PR, Simons SS, Kumar R. Binding of the N-terminal region of coactivator TIF2 to the intrinsically disordered AF1 domain of the glucocorticoid receptor is accompanied by conformational reorganizations. J Biol Chem 2012; 287:44546-60. [PMID: 23132854 DOI: 10.1074/jbc.m112.411330] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Control of gene transcription by glucocorticoid receptors (GRs) is important for many physiological processes. Like other steroid hormone receptors, the regulation of target genes by GR is mediated by two transactivation domains: activation function 1 (AF1) in the N-terminal domain and AF2 in the C-terminal ligand-binding domain (LBD). Full receptor activity requires both AF1 and -2 plus assorted coregulatory proteins. Crystal structures of the ligand-bound LBD have provided insight regarding how AF2 interacts with specific coactivators. However, despite its being the major activation domain of GRs, knowledge of AF1 structure/function has languished. This is mainly because of the highly disorganized structure of the GR N-terminal domain. This lack of AF1 structure is shared by all members of the steroid/nuclear receptor superfamily for which it has been examined and AF1 is thought to allow productive interactions with assorted cofactors via protein-induced changes in secondary/tertiary structures. To date, there are no reports of a classical coactivator altering the secondary/tertiary structure of the GR AF1 domain. Earlier, we reported an N-terminal fragment of the p160 coactivator TIF2, called TIF2.0, that binds the GR N-terminal domain and alters GR transcriptional activity. We therefore proposed that TIF2.0 binding to AF1 changes both its conformation and transcriptional activity. We now report that TIF2.0 interacts with the GR AF1 domain to increase the amount of α-helical structure in the complex. Furthermore, TIF2 coactivator activity is observed in the absence of the GR LBD in a manner that requires the AF1 domain. This contrasts with previous models where TIF2 receptor interaction domains binding to GR LBD somehow alter AF1 conformation. Our results establish for the first time that coactivators can modify the structure of the AF1 domain directly via the binding of a second region of the coactivator and suggest a molecular explanation for how coactivators increase the transcriptional activity of GR-agonist complexes.
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Affiliation(s)
- Shagufta H Khan
- Department of Basic Sciences, The Commonwealth Medical College, Scranton, Pennsylvania 18509, USA
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9
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Awasthi S, Simons SS. Separate regions of glucocorticoid receptor, coactivator TIF2, and comodulator STAMP modify different parameters of glucocorticoid-mediated gene induction. Mol Cell Endocrinol 2012; 355:121-34. [PMID: 22342989 PMCID: PMC3312974 DOI: 10.1016/j.mce.2012.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 02/02/2012] [Indexed: 11/16/2022]
Abstract
Increased specificity in steroid-regulated gene expression is a long-sought goal of endocrinologists. Considerable progress has resulted from the discovery of coactivators, corepressors, and comodulators that adjust the total activity (A(max)) of gene induction. Two less frequently quantitated, but equally potent, means of improving specificity are the concentration of agonist steroid required for half-maximal activity (EC(50)) and the residual or partial agonist activity displayed by most antisteroids (PAA). It is usually assumed that the modulatory activity of transcriptional cofactors coordinately regulates A(max), EC(50), and PAA. Here we examine the hypothesis that these three parameters can be independently modified by separate protein domains. The test system involves three differently sized fragments of each of three factors (glucocorticoid receptor [GR], coactivator TIF2, and comodulator STAMP), which are shown to form a ternary complex and similarly affect the induction properties of transfected and endogenous genes. Twenty-five different fragment combinations of the ternary complex are examined for their ability to modulate the A(max), EC(50), and PAA of a transiently transfected synthetic reporter gene. Different combinations selectively alter one, two, or all three parameters. These results clearly demonstrate that A(max), EC(50), and PAA can be independently regulated under some conditions by different pathways or molecular interactions. This new mechanistic insight suggests that selected activities of individual transcription factors are attractive targets for small molecules, which would have obvious clinical applications for increasing the specificity of steroids during endocrine therapies.
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Affiliation(s)
- Smita Awasthi
- Steroid Hormones Section, NIDDK/LERB, National Institutes of Health, Bethesda, MD, United States
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10
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Hadley KE, Louw A, Hapgood JP. Differential nuclear localisation and promoter occupancy play a role in glucocorticoid receptor ligand-specific transcriptional responses. Steroids 2011; 76:1176-84. [PMID: 21641918 DOI: 10.1016/j.steroids.2011.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2010] [Revised: 04/20/2011] [Accepted: 05/18/2011] [Indexed: 10/18/2022]
Abstract
The glucocorticoid receptor (GR) is a ligand-activated transcription factor for which a number of endogenous and synthetic ligands exist. A key question in steroid receptor biology is how different ligands elicit different maximal transcriptional responses via the same receptor and on the same promoter. This question was addressed quantitatively for the GR, using a panel of agonists, partial agonists and antagonists, on the endogenous GILZ gene in two different human cell lines. It was found that the extent of GR nuclear localization correlated with the efficacy for GILZ transactivation by the GR in U2OS cells. However, in A549 cells there was no significant correlation, with all ligands resulting in similar levels of GR nuclear localization, despite different levels of transcriptional activation of the GILZ gene. Chromatin immunoprecipitation analysis on the other hand, revealed ligand-specific differences in GILZ promoter occupancy in the A549 cells, which correlated with the transcriptional efficacy of the subset of ligands investigated. This suggests that ligand-specific differences in promoter occupancy by activated GR play a major role in discrimination between agonist, partial agonist and antagonist responses on the endogenous GILZ gene in A549 cells, while differences in nuclear localisation of liganded GR play a role in determining the transcriptional outcome in U2OS cells. These cell line-specific differences were not dependent on the amount of GR present, since transient overexpression of GR in U2OS did not alter the relative ligand-selective nuclear localisation. Our results show that there is a relationship between ligand-specific transactivation efficacy, extent of nuclear translocation and recruitment of GR to the promoter. However, the relative contribution of nuclear translocation and GR promoter recruitment to ligand-specific transactivation efficacy is cell-specific.
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Affiliation(s)
- Katie E Hadley
- Department of Molecular and Cell Biology, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
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11
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Gross KL, Oakley RH, Scoltock AB, Jewell CM, Cidlowski JA. Glucocorticoid receptor alpha isoform-selective regulation of antiapoptotic genes in osteosarcoma cells: a new mechanism for glucocorticoid resistance. Mol Endocrinol 2011; 25:1087-99. [PMID: 21527497 DOI: 10.1210/me.2010-0051] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Glucocorticoids regulate a variety of physiological processes and are commonly used to treat disorders of inflammation, autoimmune diseases, and cancer. Glucocorticoid action is predominantly mediated through the classic glucocorticoid receptor (GR)α isoform. Recent data suggest that the mature GRα mRNA is translated into multiple N-terminal isoforms that have distinct biochemical properties and gene regulatory profiles. Interestingly, osteosarcoma cells stably expressing the GRα-D translational isoform are unique in that they are resistant to glucocorticoid-induced apoptosis. In this study, we investigate whether GRα isoform-specific differences in the regulation of antiapoptotic genes contribute to this resistant phenotype. We now show that GRα-D, unlike the other receptor isoforms, does not inhibit the activity of a nuclear factor κB (NF-κB)-responsive reporter gene and does not efficiently repress either the transcription or protein production of the antiapoptotic genes Bcl-xL, cellular inhibitor of apoptosis protein 1, and survivin. The inability of GRα-D to down-regulate the expression of these genes appears to be associated with a diminished interaction between GRα-D and NF-κB that is observed in cells, but not in vitro, and likely reflects the sequestration of GRα-D in the nucleus. Deletion of the GRα N-terminal amino acids 98-335 also results in a nuclear resident GR, which fails to interact with NF-κB in cells and promote apoptosis in response to glucocorticoids. These data suggest that the N-terminal translational isoforms of GRα selectively regulate antiapoptotic genes and that the GRα-D isoform may contribute to the resistance of certain cancer cells to glucocorticoid-induced apoptosis.
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Affiliation(s)
- Katherine L Gross
- Molecular Endocrinology Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
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12
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Estrogen receptors recruit SMRT and N-CoR corepressors through newly recognized contacts between the corepressor N terminus and the receptor DNA binding domain. Mol Cell Biol 2010; 30:1434-45. [PMID: 20065040 DOI: 10.1128/mcb.01002-09] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Estrogen receptors (ERs) are hormone-regulated transcription factors that regulate key aspects of reproduction and development. ERs are unusual in that they do not typically repress transcription in the absence of hormone but instead possess otherwise cryptic repressive functions that are revealed upon binding to certain hormone antagonists. The roles of corepressors in the control of these aspects of ER function are complex and incompletely understood. We report here that ERs recruit SMRT through an unusual mode of interaction involving multiple contact surfaces. Two surfaces of SMRT, located at the N- and C-terminal domains, contribute to the recruitment of the corepressor to ERs in vitro and are crucial for the corepressor modulation of ER transcriptional activity in cells. These corepressor surfaces contact the DNA binding domain of the receptor, rather than the hormone binding domain previously elucidated for other corepressor/nuclear receptor interactions, and are modulated by the ER's recognition of cognate DNA binding sites. Several additional nuclear receptors, and at least one other corepressor, N-CoR, share aspects of this novel mode of corepressor recruitment. Our results highlight a molecular mechanism that helps explain several previously paradoxical aspects of ER-mediated transcriptional antagonism, which may have a broader significance for an understanding of target gene repression by other nuclear receptors.
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Ruff H, Tremmel C, Spindler-Barth M. Transcriptional activity of ecdysone receptor isoforms is regulated by modulation of receptor stability and interaction with Ab- and C-domains of the heterodimerization partner ultraspiracle. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2009; 72:154-171. [PMID: 19711356 DOI: 10.1002/arch.20309] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The stability of ecdysone receptor (EcR) expressed in a heterologous system is regulated in an isoform-specific manner and modified by ligand and heterodimerization partner. Transcriptional activities of various receptor complexes with Usp and ligand as determined by reporter assays are the result of two effects: change in receptor concentration and altered transcriptional capability. Transcriptional activity of EcR-A is low when compared to EcR-B1 independent of the absence or presence of Ultraspiracle (Usp). Ligand increased the concentration of EcR-A, but had no effect on the transcriptional capability, in contrast to EcR-B1, which is not stabilized by hormone or Usp, but the transcriptional capability is enhanced by heterodimerization and ligand. Exchange of the AB-domain of Usp by the activation domain (AD) of Vp16 revealed that the N-terminus of Usp inhibited transcriptional activity only with EcR-B isoforms, whereas the hexapeptide in the AB-domain of wild type Usp adjacent to the C-domain of Usp harbours an activating function. Deletion of the C-domain of Usp did not affect the stability of the receptor complex, but reduced the transcriptional capability of heterodimers with all EcR-isoforms, indicating that the stability of the receptor, which is important for termination of the hormone signal transduction, is regulated in a cooperative manner by the AB-domains of EcR and Usp, and ligand. We show the active role of Usp in modulation of the transcriptional activity of the heterodimer in an isoform-specific manner by the inhibitory N-terminus, the activating hexapeptide in the AB-domain, and the C-domain of Usp.
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Affiliation(s)
- Heike Ruff
- Institute of General Zoology and Endocrinology, University of Ulm, Ulm, Germany
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14
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Ronacher K, Hadley K, Avenant C, Stubsrud E, Simons SS, Louw A, Hapgood JP. Ligand-selective transactivation and transrepression via the glucocorticoid receptor: role of cofactor interaction. Mol Cell Endocrinol 2009; 299:219-31. [PMID: 19007848 DOI: 10.1016/j.mce.2008.10.008] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Accepted: 10/12/2008] [Indexed: 01/08/2023]
Abstract
The mechanisms that determine ligand-selective transcriptional responses by the glucocorticoid receptor (GR) are not fully understood. Using a wide panel of GR ligands, we investigated the relationships between the potency and maximal response for transactivation via a glucocorticoid response element (GRE) and transrepression via both nuclear factor small ka, CyrillicB (NFsmall ka, CyrillicB) and activator protein-1 (AP-1) sites, relative binding affinity for the GR, as well as interaction with both coactivators and corepressors. The results showed ligand-selective differences in potency and efficacy for each promoter, as well as for a particular ligand between the three promoters. Ligand potency correlated with relative affinity for the GR for agonists and partial agonists in transactivation but not for transrepression. Maximal response was unrelated to relative affinity of ligand for GR for both transactivation and transrepression. A good and significant correlation between full length coactivator binding in two-hybrid assays and efficacy as well as potency of different receptor-steroid complexes for both transactivation and transrepression supports a major role for coactivator recruitment in determination of ligand-selective transcriptional activity. Furthermore, ligand-selective GR binding to GRIP-1, as determined by both two-hybrid and DNA pull down assays, correlated positively with ligand-selective efficacy for transactivation of both a synthetic GRE reporter with expressed GR as well as of an endogenous gene via endogenous GR. The receptor interacting domain of the corepressor SMRT exhibited strong interaction with both agonists and partial agonists, similar to the results for coactivators, suggesting a possible role for SMRT in activation of transcription. However, there was no correlation between ligand affinity for the GR and cofactor interaction. These results provide strong quantitative biochemical support for a model in which GR-mediated ligand-selective differential interaction with GRIP-1, SRC-1A, NCoR and SMRT is a major determinant of ligand-selective and promoter-specific differences in potency and efficacy, for both transactivation and transrepression.
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Affiliation(s)
- Katharina Ronacher
- Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
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15
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Shah V, Nguyen P, Nguyen NH, Togashi M, Scanlan TS, Baxter JD, Webb P. Complex actions of thyroid hormone receptor antagonist NH-3 on gene promoters in different cell lines. Mol Cell Endocrinol 2008; 296:69-77. [PMID: 18930112 PMCID: PMC4180716 DOI: 10.1016/j.mce.2008.09.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Revised: 09/11/2008] [Accepted: 09/11/2008] [Indexed: 12/20/2022]
Abstract
It is desirable to obtain new antagonists for thyroid hormone receptors (TRs) and other nuclear receptors (NRs). We previously used X-ray structural models of TR ligand binding domains (LBDs) to design compounds, such as NH-3, that impair coactivator binding to activation function 2 (AF-2) and block thyroid hormone (triiodothyronine, T(3)) actions. However, TRs bind DNA and are transcriptionally active without ligand. Thus, NH-3 could modulate TR activity via effects on other coregulator interaction surfaces, such as activation function (AF-1) and corepressor binding sites. Here, we find that NH-3 blocks TR-LBD interactions with coactivators and corepressors and also inhibits activities of AF-1 and AF-2 in transfections. While NH-3 lacks detectable agonist activity at T(3)-activated genes in GC pituitary cells it nevertheless activates spot 14 (S14) in HTC liver cells with the latter effect accompanied by enhanced histone H4 acetylation and coactivator recruitment at the S14 promoter. Surprisingly, T(3) promotes corepressor recruitment to target promoters. NH-3 effects vary; we observe transient recruitment of N-CoR to S14 in GC cells and dismissal and rebinding of N-CoR to the same promoter in HTC cells. We propose that NH-3 will generally behave as an antagonist by blocking AF-1 and AF-2 but that complex effects on coregulator recruitment may result in partial/mixed agonist effects that are independent of blockade of T(3) binding in some contexts. These properties could ultimately be utilized in drug design and development of new selective TR modulators.
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Affiliation(s)
- Vanya Shah
- Diabetes Center and Department of Medicine, University of California, San Francisco, CA94143
| | - Phuong Nguyen
- Diabetes Center and Department of Medicine, University of California, San Francisco, CA94143
| | - Ngoc-Ha Nguyen
- Departments of Pharmaceutical Chemistry and Molecular & Cellular Pharmacology, University of California, San Francisco, CA94143
| | - Marie Togashi
- Diabetes Center and Department of Medicine, University of California, San Francisco, CA94143
- Molecular Pharmacology, Department of Pharmaceutical Sciences, School of Health Sciences, University of Brasilia, Brazil
| | - Thomas S. Scanlan
- Departments of Pharmaceutical Chemistry and Molecular & Cellular Pharmacology, University of California, San Francisco, CA94143
- Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR97239
| | - John D. Baxter
- Diabetes Center and Department of Medicine, University of California, San Francisco, CA94143
- Methodist Hospital Research Institute, Houston TX77030
| | - Paul Webb
- Diabetes Center and Department of Medicine, University of California, San Francisco, CA94143
- Methodist Hospital Research Institute, Houston TX77030
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16
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Sun Y, Tao YG, Kagan BL, He Y, Simons SS. Modulation of transcription parameters in glucocorticoid receptor-mediated repression. Mol Cell Endocrinol 2008; 295:59-69. [PMID: 18583028 PMCID: PMC2662735 DOI: 10.1016/j.mce.2008.05.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Revised: 05/09/2008] [Accepted: 05/13/2008] [Indexed: 12/25/2022]
Abstract
Glucocorticoid receptors (GRs) affect both gene induction and gene repression. The disparities of receptor binding to DNA and increased vs. decreased gene expression have suggested significant mechanistic differences between GR-mediated induction and repression. Numerous transcription factors are known to modulate three parameters of gene induction: the total activity (Vmax) and position of the dose-response curve with glucocorticoids (EC50) and the percent partial agonist activity with antiglucocorticoids. We have examined the effects on GR-mediated repression of five modulators (coactivators TIF2 [GRIP1, SRC-2] and SRC-1, corepressor SMRT, and comodulators STAMP and Ubc9), a glucocorticoid steroid (deacylcortivazol [DAC]) of very different structure, and an inhibitor of histone deacetylation (trichostatin A [TSA]). These factors interact with different domains of GR and thus are sensitive topological probes of GR action. These agents altered the Vmax, EC50, and percent partial agonist activity of endogenous and exogenous repressed genes similarly to that previously observed for GR-regulated gene induction. Collectively, these results suggest that GR-mediated induction and repression share many of the same molecular interactions and that the causes for different levels of gene transcription arise from more distal downstream steps.
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Affiliation(s)
| | | | | | | | - S. Stoney Simons
- Address correspondence to Dr. S. Stoney Simons, Jr., Bldg. 10, Room 8N-307B, NIDDK/CEB, NIH, Bethesda, MD 20892-1772 (Phone: 301-496-6796; FAX: 301-402-3572; e-mail: )
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17
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Simons SS. What goes on behind closed doors: physiological versus pharmacological steroid hormone actions. Bioessays 2008; 30:744-56. [PMID: 18623071 DOI: 10.1002/bies.20792] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Steroid-hormone-activated receptor proteins are among the best-understood class of factors for altering gene transcription in cells. Steroid receptors are of major importance in maintaining normal human physiology by responding to circulating concentrations of steroid in the nM range. Nonetheless, most studies of steroid receptor action have been conducted using the supra-physiological conditions of saturating concentrations (> or =100 nM) of potent synthetic steroid agonists. Here we summarize the recent developments arising from experiments using two clinically relevant conditions: subsaturating concentrations of agonist (to mimic the circulating concentrations in mammals) and saturating concentrations of antagonists (which are employed in endocrine therapies to block the actions of endogenous steroids). These studies have revealed new facets of steroid hormone action that could not be uncovered by conventional experiments with saturating concentrations of agonist steroids, such as a plethora of factors/conditions for the differential control of gene expression by physiological levels of steroid, a rational approach for examining the gene-specific variations in partial agonist activity of antisteroids, and a dissociation of steroid potency and efficacy that implies the existence of separate, and possibly novel, mechanistic steps and cofactors.
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Affiliation(s)
- S Stoney Simons
- Steroid Hormones Section, Bldg 10, Room 8N-307B, NIDDK/CEB, NIH, Bethesda, MD 20892-1772, USA
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18
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Song LN, Gelmann EP. Silencing mediator for retinoid and thyroid hormone receptor and nuclear receptor corepressor attenuate transcriptional activation by the beta-catenin-TCF4 complex. J Biol Chem 2008; 283:25988-99. [PMID: 18632669 DOI: 10.1074/jbc.m800325200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
beta-Catenin is a multifunctional mediator of cellular signaling and an oncogene. Nuclear beta-catenin, when complexed with members of the T-cell factor (TCF)/leukocyte enhancer factor family of DNA-binding proteins, mediates transcriptional activation important for embryonic development and adult cell homeostasis. Deregulation of intracellular levels of beta-catenin is an early event in the development of a variety of cancers. We observed that the proteins silencing mediator for retinoid and thyroid hormone receptor (SMRT) and the nuclear receptor corepressor (NCoR) are negative regulators of transcription induced by the beta-catenin-TCF4 complex. Overexpression of SMRT and NCoR attenuated the transcription of beta-catenin-TCF4-specific reporter gene and of CCND1, an endogenous beta-catenin target gene. Knockdown of endogenous SMRT or NCoR by short interfering RNA augmented the beta-catenin-TCF4-mediated reporter gene expression. Glutathione S-transferase pulldown experiments showed there was a direct physical association of SMRT and NCoR with both beta-catenin and TCF4. DNA-protein interaction studies revealed that the interactions between either SMRT or NCoR and beta-catenin or TCF4 occurred at the promoter regions of CCND1 and other target genes. These findings demonstrate an important role for corepressors SMRT and NCoR in the regulation of beta-catenin-TCF4-mediated gene transcription.
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Affiliation(s)
- Liang-Nian Song
- Department of Medicine, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York 10032, USA
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19
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Tao YG, Xu Y, Xu HE, Simons SS. Mutations of glucocorticoid receptor differentially affect AF2 domain activity in a steroid-selective manner to alter the potency and efficacy of gene induction and repression. Biochemistry 2008; 47:7648-62. [PMID: 18578507 DOI: 10.1021/bi800472w] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The transcriptional activity of steroid hormones is intimately associated with their structure. Deacylcortivazol (DAC) contains several features that were predicted to make it an inactive glucocorticoid. Nevertheless, gene induction and repression by complexes of glucocorticoid receptor (GR) with DAC occur with potency (lower EC 50) greater than and efficacy (maximal activity, or A max) equal to those of the very active and smaller synthetic glucocorticoid dexamethasone (Dex). Guided by a recent X-ray structure of DAC bound to the GR ligand binding domain (LBD), we now report that several point mutants in the LBD have little effect on the binding of either agonist steroid. However, these same mutations dramatically alter the A max and/or EC 50 of exogenous and endogenous genes in a manner that depends on steroid structure. In some cases, Dex is no longer a full agonist. These properties appear to result from a preferential inactivation of the AF2 activation domain in the GR LBD of Dex-bound, but not DAC-bound, receptors. The Dex-bound receptors display normal binding to, but a greatly reduced response to, the coactivator TIF2, thus indicating a defect in the transmission efficiency of GR-steroid complex information to the coactivator TIF2. In addition, all GR mutants that are active in gene induction with either Dex or DAC have greatly reduced activity in gene repression. This contrasts with the reports of GR mutations preferentially suppressing GR-mediated induction. The properties of these GR mutants in gene induction support the hypothesis that the A max and EC 50 of GR-controlled gene expression can be independently modified, indicate that the receptor can be modified to favor activity with a specific agonist steroid, and suggest that new ligands with suitable substituents may be able to affect the same LBD conformational changes and thereby broaden the therapeutic applications of glucocorticoid steroids.
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Affiliation(s)
- Yong-guang Tao
- Steroid Hormones Section, National Institute of Diabetes and Digestive and Kidney Diseases/Clinical Endocrinology Branch, National Institutes of Health, Bethesda, Maryland 20892, USA
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20
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Szapary D, Song LN, He Y, Simons SS. Differential modulation of glucocorticoid and progesterone receptor transactivation. Mol Cell Endocrinol 2008; 283:114-26. [PMID: 18215457 PMCID: PMC2275900 DOI: 10.1016/j.mce.2007.11.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 11/29/2007] [Indexed: 01/13/2023]
Abstract
The determinants of the different biological activities of progesterone receptors (PRs) vs. glucocorticoid receptors (GRs), which bind to the same DNA sequences, remain poorly understood. The mechanisms by which differential expression of a common target gene can be achieved by PR and GR include unequal agonist steroid concentrations for half maximal induction (EC50) and dissimilar amounts of residual partial agonist activity for antisteroids in addition to the more common changes in total gene induction, or Vmax. Several factors are known to alter some or all of these three parameters for GR-regulated gene induction and some (i.e., the corepressors NCoR and SMRT) modulate the EC50 and partial agonist activity for GR and PR induction of the same gene in opposite directions. The current study demonstrates that other factors known to modulate GR properties (GME, GMEB-2, Ubc9, and STAMP) can also differentially interact with PRs or alter several of the above induction parameters under otherwise identical conditions. These results support the hypothesis that the modulation of EC50, partial agonist activity, and Vmax by a given factor is not limited to one receptor in a specific cell line. Furthermore, the number of factors that unequally modulate PR and GR induction parameters is now greatly expanded, thereby increasing the possible mechanisms for differential gene regulation by PRs vs. GRs.
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Affiliation(s)
- Daniele Szapary
- Steroid Hormones Section, NIDDK/CEB, National Institutes of Health, Bethesda, MD 20892-1772, United States
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21
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van der Laan S, Lachize SB, Vreugdenhil E, de Kloet ER, Meijer OC. Nuclear receptor coregulators differentially modulate induction and glucocorticoid receptor-mediated repression of the corticotropin-releasing hormone gene. Endocrinology 2008; 149:725-32. [PMID: 18006628 DOI: 10.1210/en.2007-1234] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Nuclear receptor coregulators are proteins that modulate the transcriptional activity of steroid receptors and may explain cell-specific effects of glucocorticoid receptor action. Based on the uneven distribution of a number of coregulators in CRH-expressing cells in the hypothalamus of the rat brain, we tested the hypothesis that these proteins are involved as mediators in the glucocorticoid-induced repression of the CRH promoter. Therefore, we assessed the role of coregulator proteins on both induction and repression of CRH in the AtT-20 cell line, a model system for CRH repression by glucocorticoids. The steroid receptor coactivator 1a (SRC1a), SRC-1e, nuclear corepressor (N-CoR), and silencing mediator of the retinoid and thyroid hormone receptor (SMRT) were studied in this system. We show that the concentration of glucocorticoid receptor and the type of ligand, i.e. corticosterone or dexamethasone, determines the repression. Furthermore, overexpression of SRC1a, but not SRC1e, increased both efficacy and potency of the glucocorticoid receptor-mediated repression of the forskolin-induced CRH promoter. Unexpectedly, cotransfection of the corepressors N-CoR and SMRT did not affect the corticosterone-dependent repression but resulted in a marked decrease of the forskolin stimulation of the CRH gene. Altogether, our data demonstrate that 1) the concentration of the receptor, 2) the type of ligand, and 3) the coregulator recruited all determine the expression and the repression of the CRH gene. We conclude that modulation of coregulator activity may play a role in the control of the hypothalamus-pituitary-adrenal axis.
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Affiliation(s)
- S van der Laan
- Division of Medical Pharmacology, Leiden/Amsterdam Centre for Drug Research and Leiden University Medical Centre, 2300 RA, Leiden, The Netherlands.
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22
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Antiinflammatory glucocorticoid receptor ligand with reduced side effects exhibits an altered protein-protein interaction profile. Proc Natl Acad Sci U S A 2007; 104:19244-9. [PMID: 18032610 DOI: 10.1073/pnas.0705517104] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Glucocorticoids are commonly used antiinflammatory agents whose use is limited by side effects. We have developed a series of glucocorticoid receptor (GR) ligands that retain the strong antiinflammatory activity of conventional glucocorticoids with reduced side effects. We present a compound, LGD5552, that binds the receptor efficiently and strongly represses inflammatory gene expression. LGD5552 bound to GR activates gene expression somewhat differently than glucocorticoids. It activates some genes with an efficacy similar to that of the glucocorticoids. However, other glucocorticoid-activated genes are not regulated by LGD5552. These differences may be because of the more efficient binding of corepressor in the presence of LGD5552, compared with glucocorticoid agonists. This class of nonsteroidal, GR-dependent antiinflammatory drugs may offer a safer alternative to steroidal glucocorticoids in the treatment of inflammatory disease.
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23
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Zhang S, Jonklaas J, Danielsen M. The glucocorticoid agonist activities of mifepristone (RU486) and progesterone are dependent on glucocorticoid receptor levels but not on EC50 values. Steroids 2007; 72:600-8. [PMID: 17509631 DOI: 10.1016/j.steroids.2007.03.012] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 03/10/2007] [Accepted: 03/27/2007] [Indexed: 11/28/2022]
Abstract
Mifepristone is an antagonist of the glucocorticoid receptor (GR) that also has significant agonist activity in some cell types. We examined the partial agonist activity of mifepristone in COS-7 cells transfected with increasing amounts of a glucocorticoid receptor expression vector pmGR. As pmGR levels increased, the response of the reporter, pMTVCAT to dexamethasone increased, consistent with increasing levels of receptor expression; the response to mifepristone also increased but at a higher rate, resulting in increasing mifepristone agonist and decreasing antagonist activity. In contrast, increasing pMTVCAT levels increased CAT activity induced by both dexamethasone and mifepristone, but did not change the relative agonist activity of mifepristone. We also examined the relationship between agonist activity and receptor level in a series of clones of the E8.2.A3 cell line expressing various levels of GR. Again, the relative agonist activity of mifepristone increased as GR increased. This increase was not due to changes in the dose response curves to these two ligands since their EC50 values were independent of receptor levels. These results indicate that the degree of glucocorticoid agonist activity exhibited by mifepristone is dependent on the concentration of GR in the cell. Similar results were obtained with another partial agonist of the GR, progesterone, whereas the complete antagonist ZK98.299 had no agonist activity under any condition. Taken together, these results suggest that the phenomenon of receptor concentration-dependence is a property of partial GR agonists in general.
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Affiliation(s)
- Shimin Zhang
- Division of Molecular Pathobiology, Department of Environmental and Infectious Disease Sciences, American Registry of Pathology, Armed Forces Institute of Pathology, Washington, DC 20306, USA.
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24
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Heldring N, Pawson T, McDonnell D, Treuter E, Gustafsson JA, Pike ACW. Structural insights into corepressor recognition by antagonist-bound estrogen receptors. J Biol Chem 2007; 282:10449-55. [PMID: 17283072 DOI: 10.1074/jbc.m611424200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Direct recruitment of transcriptional corepressors to estrogen receptors (ER) is thought to contribute to the tissue-specific effects of clinically important ER antagonists. Here, we present the crystal structures of two affinity-selected peptides in complex with antagonist-bound ERalpha ligand-binding domain. Both peptides adopt helical conformations, bind along the activation function 2 coregulator interaction surface, and mimic corepressor (CoRNR) sequence motif binding. Peptide binding is weak in a wild-type context but significantly enhanced by removal of ER helix 12. This region contains a previously unrecognized CoRNR motif that is able to compete with corepressors for binding to activation function 2, thereby providing a structural explanation for the poor ability of ER to directly interact with classical corepressors. Furthermore, the ability of other sequence motifs to mimic corepressor binding raises the possibility that coregulators do not necessarily require CoRNR motifs for direct recruitment to antagonist-bound ER.
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Affiliation(s)
- Nina Heldring
- Department of Biosciences and Nutrition, Karolinska Institutet, S-14157 Huddinge, Sweden.
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25
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Wu Y, Kawate H, Ohnaka K, Nawata H, Takayanagi R. Nuclear compartmentalization of N-CoR and its interactions with steroid receptors. Mol Cell Biol 2006; 26:6633-55. [PMID: 16914745 PMCID: PMC1592818 DOI: 10.1128/mcb.01534-05] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The repression mechanisms by the nuclear receptor corepressor (N-CoR) of steroid hormone receptor (SHR)-mediated transactivation were examined. Yellow fluorescent protein (YFP)-N-CoR was distributed as intranuclear discrete dots, while coexpression of androgen receptor (AR), glucocorticoid receptor alpha, and estrogen receptor alpha ligand-dependently triggered redistribution of YFP-N-CoR. In fluorescence recovery after photobleaching analysis, mobility of the N-CoR was reduced by 5alpha-dihydrotestosterone (DHT)-bound AR. The middle region of N-CoR mostly contributed to the interaction with agonist-bound SHRs and the suppression of their transactivation function. N-CoR impaired the DHT-induced N-C interaction of AR, and the impaired interaction was dose-dependently recovered by coexpression of SRC-1 and CBP. N-CoR also impaired the intranuclear complete (distinct) focus formation of SHRs. Coexpression of SRC-1 or CBP released YFP-N-CoR or endogenous N-CoR from incomplete foci and simultaneously recovered complete foci of AR-green fluorescent protein. These results indicate that the relative ratio of coactivators and corepressors determines the conformational equilibrium between transcriptionally active and inactive SHRs in the presence of agonists. The intranuclear foci formed by agonist-bound SHRs were completely destroyed by actinomycin D and alpha-amanitin, indicating that the focus formation does not precede the transcriptional activation. The focus formation may reflect the accumulation of SHR/coactivator complexes released from the transcriptionally active sites and thus be a mirror of transcriptionally active complex formation.
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Affiliation(s)
- Yin Wu
- Department of Geriatric Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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26
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Goldman S, Shalev E. A proposed mechanism for progesterone regulation of trophoblast MMP2 transcription independent of classical progesterone response elements on its promoter. JOURNAL OF EXPERIMENTAL & CLINICAL ASSISTED REPRODUCTION 2006; 3:4. [PMID: 16600042 PMCID: PMC1459195 DOI: 10.1186/1743-1050-3-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2005] [Accepted: 04/06/2006] [Indexed: 01/04/2023]
Abstract
Background Progesterone receptor act as ligand-inducible transcription factor in the respective target cells by binding to specific progesterone response elements in the promoter of the target genes. However, despite the lack of the classical progesterone response elements on matrix-metalloproteinase-2 promoter, progesterone has been shown to decrease the activity of this promoter Presentation of the hypothesis It has recently been suggested that in addition to interacting with their classical co-activators and co-repressors, progesterone receptor are capable of binding to several transcription factors. By interacting with other classes of transcription factors, progesterone receptor is capable of transcriptional activation through the transcription factors cognate DNA binding site. Testing the hypothesis Exploring transcription factors and transcription binding sites, interacting with the progesterone receptor in modulation of the matrix-metalloproteinase promoter. Implications of the hypothesis Identification of additional endogenous progesterone target genes makes it possible to further explore the signaling mechanisms by which the hormone regulates biological actions. Furthermore, the concepts of ligand-driven conformational diversity and selective tissue actions can be exploited in the future for drug development which selectively regulate orphan receptors from the nuclear receptor family.
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Affiliation(s)
- Shlomit Goldman
- Laboratory for Research in Reproductive Sciences, Department of Obstetrics and Gynecology, Ha'Emek Medical Center, 18101, Afula, Israel
| | - Eliezer Shalev
- Laboratory for Research in Reproductive Sciences, Department of Obstetrics and Gynecology, Ha'Emek Medical Center, 18101, Afula, Israel
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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27
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Lavery D, Mcewan I. Structure and function of steroid receptor AF1 transactivation domains: induction of active conformations. Biochem J 2006; 391:449-64. [PMID: 16238547 PMCID: PMC1276946 DOI: 10.1042/bj20050872] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Steroid hormones are important endocrine signalling molecules controlling reproduction, development, metabolism, salt balance and specialized cellular responses, such as inflammation and immunity. They are lipophilic in character and act by binding to intracellular receptor proteins. These receptors function as ligand-activated transcription factors, switching on or off networks of genes in response to a specific hormone signal. The receptor proteins have a conserved domain organization, comprising a C-terminal LBD (ligand-binding domain), a hinge region, a central DBD (DNA-binding domain) and a highly variable NTD (N-terminal domain). The NTD is structurally flexible and contains surfaces for both activation and repression of gene transcription, and the strength of the transactivation response has been correlated with protein length. Recent evidence supports a structural and functional model for the NTD that involves induced folding, possibly involving alpha-helix structure, in response to protein-protein interactions and structure-stabilizing solutes.
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Affiliation(s)
- Derek N. Lavery
- School of Medical Sciences, College of Life Sciences and Medicine, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, U.K
| | - Iain J. Mcewan
- School of Medical Sciences, College of Life Sciences and Medicine, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, U.K
- To whom correspondence should be addressed (email )
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