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Blatt EB, Kopplin N, Kumar S, Mu P, Conzen SD, Raj GV. Overcoming oncogene addiction in breast and prostate cancers: a comparative mechanistic overview. Endocr Relat Cancer 2021; 28:R31-R46. [PMID: 33263560 PMCID: PMC8218927 DOI: 10.1530/erc-20-0272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023]
Abstract
Prostate cancer (PCa) and breast cancer (BCa) are both hormone-dependent cancers that require the androgen receptor (AR) and estrogen receptor (ER, ESR1) for growth and proliferation, respectively. Endocrine therapies that target these nuclear receptors (NRs) provide significant clinical benefit for metastatic patients. However, these therapeutic strategies are seldom curative and therapy resistance is prevalent. Because the vast majority of therapy-resistant PCa and BCa remain dependent on the augmented activity of their primary NR driver, common mechanisms of resistance involve enhanced NR signaling through overexpression, mutation, or alternative splicing of the receptor, coregulator alterations, and increased intracrine hormonal synthesis. In addition, a significant subset of endocrine therapy-resistant tumors become independent of their primary NR and switch to alternative NR or transcriptional drivers. While these hormone-dependent cancers generally employ similar mechanisms of endocrine therapy resistance, distinct differences between the two tumor types have been observed. In this review, we compare and contrast the most frequent mechanisms of antiandrogen and antiestrogen resistance, and provide potential therapeutic strategies for targeting both advanced PCa and BCa.
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Affiliation(s)
- Eliot B Blatt
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Noa Kopplin
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Shourya Kumar
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ping Mu
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Suzanne D Conzen
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ganesh V Raj
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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2
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Eraso Y. Oestrogen receptors and breast cancer: are we prepared to move forward? A critical review. BIOSOCIETIES 2019. [DOI: 10.1057/s41292-019-00173-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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3
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O'Malley BW. Origins of the Field of Molecular Endocrinology: A Personal Perspective. Mol Endocrinol 2018; 30:1015-1018. [PMID: 27690769 DOI: 10.1210/me.2016-1132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Jara EL, Muñoz-Durango N, Llanos C, Fardella C, González PA, Bueno SM, Kalergis AM, Riedel CA. Modulating the function of the immune system by thyroid hormones and thyrotropin. Immunol Lett 2017; 184:76-83. [PMID: 28216261 DOI: 10.1016/j.imlet.2017.02.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/14/2017] [Accepted: 02/15/2017] [Indexed: 12/18/2022]
Abstract
Accumulating evidence suggests a close bidirectional communication and regulation between the neuroendocrine and immune systems. Thyroid hormones (THs) can exert responses in various immune cells, e.g., monocytes, macrophages, natural killer cells, and lymphocytes, affecting several inflammation-related processes (such as, chemotaxis, phagocytosis, reactive oxygen species generation, and cytokines production). The interactions between the endocrine and immune systems have been shown to contribute to pathophysiological conditions, including sepsis, inflammation, autoimmune diseases and viral infections. Under these conditions, TH therapy could contribute to restoring normal physiological functions. Here we discuss the effects of THs and thyroid stimulating hormone (TSH) on the immune system and the contribution to inflammation and pathogen clearance, as well as the consequences of thyroid pathologies over the function of the immune system.
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Affiliation(s)
- Evelyn L Jara
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile
| | - Natalia Muñoz-Durango
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile
| | - Carolina Llanos
- Departamento de Inmunología Clínica y Reumatología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 350, Santiago, Chile
| | - Carlos Fardella
- Millennium Institute on Immunology and Immunotherapy, Departamento de Endocrinología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 350, Santiago, Chile
| | - Pablo A González
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile
| | - Susan M Bueno
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile
| | - Alexis M Kalergis
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Portugal 49, Santiago, Chile; Millennium Institute on Immunology and Immunotherapy, Departamento de Endocrinología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 350, Santiago, Chile; INSERM U1064, Nantes, France.
| | - Claudia A Riedel
- Millenium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas y Facultad de Medicina, Universidad Andrés Bello, Chile.
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Chen Q, Wang X, Shi W, Yu H, Zhang X, Giesy JP. Identification of Thyroid Hormone Disruptors among HO-PBDEs: In Vitro Investigations and Coregulator Involved Simulations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:12429-12438. [PMID: 27737548 DOI: 10.1021/acs.est.6b02029] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Some hydroxylated polybrominated diphenyl ethers (HO-PBDEs), that have been widely detected in the environment and tissues of humans and wildlife, bind to thyroid hormone (TH) receptor (TR) and can disrupt functioning of systems modulated by the TR. However, mechanisms of TH disrupting effects are still equivocal. Here, disruption of functions of TH modulated pathways by HO-PBDEs was evaluated by assays of competitive binding, coactivator recruitment, and proliferation of GH3 cells. In silico simulations considering effects of coregulators were carried out to investigate molecular mechanisms and to predict potencies for disrupting functions of the TH. Some HO-PBDEs were able to bind to TR with moderate affinities but were not agonists. In GH3 proliferation assays, 13 out of 16 HO-PBDEs were antagonists for the TH. In silico simulations of molecular dynamics revealed that coregulators were essential for identification of TH disruptors. Among HO-PBDEs, binding of passive antagonists induced repositioning of H12, blocking AF-2 (transactivation function 2) and preventing recruitment of the coactivator. Binding of active antagonists exposed the coregulator binding site, which tended to bind to the corepressor rather than the coactivator. By considering both passive and active antagonisms, anti-TH potencies of HO-PBDEs could be predicted from free energy of binding.
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Affiliation(s)
- Qinchang Chen
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University , Nanjing 210023, PR China
| | - Xiaoxiang Wang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University , Nanjing 210023, PR China
- Multiphase Chemistry Department, Max Planck Institute for Chemistry , 55128 Mainz, Germany
| | - Wei Shi
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University , Nanjing 210023, PR China
| | - Hongxia Yu
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University , Nanjing 210023, PR China
| | - Xiaowei Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University , Nanjing 210023, PR China
| | - John P Giesy
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University , Nanjing 210023, PR China
- Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan , Saskatoon, Saskatchewan S7N 5B4, Canada
- Department of Zoology and Center for Integrative Toxicology, Michigan State University , East Lansing, Michigan 48824, United States
- School of Biological Sciences, University of Hong Kong , Hong Kong, SAR, China
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6
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Astapova I. Role of co-regulators in metabolic and transcriptional actions of thyroid hormone. J Mol Endocrinol 2016; 56:73-97. [PMID: 26673411 DOI: 10.1530/jme-15-0246] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 12/16/2015] [Indexed: 12/18/2022]
Abstract
Thyroid hormone (TH) controls a wide range of physiological processes through TH receptor (TR) isoforms. Classically, TRs are proposed to function as tri-iodothyronine (T3)-dependent transcription factors: on positively regulated target genes, unliganded TRs mediate transcriptional repression through recruitment of co-repressor complexes, while T3 binding leads to dismissal of co-repressors and recruitment of co-activators to activate transcription. Co-repressors and co-activators were proposed to play opposite roles in the regulation of negative T3 target genes and hypothalamic-pituitary-thyroid axis, but exact mechanisms of the negative regulation by TH have remained elusive. Important insights into the roles of co-repressors and co-activators in different physiological processes have been obtained using animal models with disrupted co-regulator function. At the same time, recent studies interrogating genome-wide TR binding have generated compelling new data regarding effects of T3, local chromatin structure, and specific response element configuration on TR recruitment and function leading to the proposal of new models of transcriptional regulation by TRs. This review discusses data obtained in various mouse models with manipulated function of nuclear receptor co-repressor (NCoR or NCOR1) and silencing mediator of retinoic acid receptor and thyroid hormone receptor (SMRT or NCOR2), and family of steroid receptor co-activators (SRCs also known as NCOAs) in the context of TH action, as well as insights into the function of co-regulators that may emerge from the genome-wide TR recruitment analysis.
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Affiliation(s)
- Inna Astapova
- Division of Endocrinology, Diabetes and MetabolismBeth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
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7
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Patel SR, Skafar DF. Modulation of nuclear receptor activity by the F domain. Mol Cell Endocrinol 2015; 418 Pt 3:298-305. [PMID: 26184856 DOI: 10.1016/j.mce.2015.07.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 07/09/2015] [Accepted: 07/09/2015] [Indexed: 10/23/2022]
Abstract
The F domain located at the C-terminus of proteins is one of the least conserved regions of the estrogen receptors alpha and beta, members of the nuclear hormone receptor superfamily. Indeed, many members of the superfamily lack the F domain. However, when present, removing the F domain entirely or mutating it alters transactivation, dimerization, and the responses to agonist and antagonist ligands. This review focuses on the functions of the F domain of the estrogen receptors, particularly in relation to other members of the superfamily.
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Affiliation(s)
- Shivali R Patel
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Debra F Skafar
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA.
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8
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Stanišić V, Lonard DM, O'Malley BW. Estrogen receptor-α: molecular mechanisms and interactions with the ubiquitin proteasome system. Horm Mol Biol Clin Investig 2015; 1:1-9. [PMID: 25961966 DOI: 10.1515/hmbci.2010.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 06/25/2009] [Indexed: 12/25/2022]
Abstract
Estrogen receptor-α (ERα) is a protein with a long history of study that precedes the advent of modern molecular biology. Over the course of 50 years, ERα has been increasingly recognized as a prominent model for the study of the mechanism of gene transcription in vertebrates. It also serves as a regulatory molecule for numerous physiological and disease states. Several fundamental insights have been made using ERα as a model protein, from the discovery that endocrine hormones elicit gene transcription to our understanding of the relationship between ERα-mediated transcription and transcription factor degradation by the ubiquitin proteasome system (UPS). Understanding of receptor protein degradation developed alongside other aspects of its molecular biology, from early observations in the 1960s that ERα is degraded on hormone treatment to the current understanding of ERα transcriptional regulation by the UPS. Here, we present the concept of ERα turnover from the perspective of the historical development of this notion and highlight some of the latest discoveries regarding this process. We discuss the logic and significance of ERα degradation pathways in the context of cell and whole-organism homeostasis.
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9
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Dasgupta S, O'Malley BW. Transcriptional coregulators: emerging roles of SRC family of coactivators in disease pathology. J Mol Endocrinol 2014; 53:R47-59. [PMID: 25024406 PMCID: PMC4152414 DOI: 10.1530/jme-14-0080] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Transcriptional coactivators have evolved as an important new class of functional proteins that participate with virtually all transcription factors and nuclear receptors (NRs) to intricately regulate gene expression in response to a wide variety of environmental cues. Recent findings have highlighted that coactivators are important for almost all biological functions, and consequently, genetic defects can lead to severe pathologies. Drug discovery efforts targeting coactivators may prove valuable for treatment of a variety of diseases.
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Affiliation(s)
- Subhamoy Dasgupta
- Department of Molecular and Cellular BiologyBaylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
| | - Bert W O'Malley
- Department of Molecular and Cellular BiologyBaylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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10
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Stashi E, York B, O'Malley BW. Steroid receptor coactivators: servants and masters for control of systems metabolism. Trends Endocrinol Metab 2014; 25:337-47. [PMID: 24953190 PMCID: PMC4108168 DOI: 10.1016/j.tem.2014.05.004] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 11/30/2022]
Abstract
Coregulator recruitment to nuclear receptors (NRs) and other transcription factors is essential for proper metabolic gene regulation, with coactivators enhancing and corepressors attenuating gene transcription. The steroid receptor coactivator (SRC) family is composed of three homologous members (SRC-1, SRC-2, and SRC-3), which are uniquely important for mediating steroid hormone and mitogenic actions. An accumulating body of work highlights the diverse array of metabolic functions regulated by the SRCs, including systemic metabolite homeostasis, inflammation, and energy regulation. We discuss here the cooperative and unique functions among the SRCs to provide a comprehensive atlas of systemic SRC metabolic regulation. Deciphering the fractional and synergistic contributions of the SRCs to metabolic homeostasis is crucial to understanding fully the networks underlying metabolic transcriptional regulation.
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Affiliation(s)
- Erin Stashi
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Brian York
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Bert W O'Malley
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.
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Ahanger SH, Günther K, Weth O, Bartkuhn M, Bhonde RR, Shouche YS, Renkawitz R. Ectopically tethered CP190 induces large-scale chromatin decondensation. Sci Rep 2014; 4:3917. [PMID: 24472778 PMCID: PMC3905270 DOI: 10.1038/srep03917] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 01/10/2014] [Indexed: 01/04/2023] Open
Abstract
Insulator mediated alteration in higher-order chromatin and/or nucleosome organization is an important aspect of epigenetic gene regulation. Recent studies have suggested a key role for CP190 in such processes. In this study, we analysed the effects of ectopically tethered insulator factors on chromatin structure and found that CP190 induces large-scale decondensation when targeted to a condensed lacO array in mammalian and Drosophila cells. In contrast, dCTCF alone, is unable to cause such a decondensation, however, when CP190 is present, dCTCF recruits it to the lacO array and mediates chromatin unfolding. The CP190 induced opening of chromatin may not be correlated with transcriptional activation, as binding of CP190 does not enhance luciferase activity in reporter assays. We propose that CP190 may mediate histone modification and chromatin remodelling activity to induce an open chromatin state by its direct recruitment or targeting by a DNA binding factor such as dCTCF.
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Affiliation(s)
- Sajad H Ahanger
- 1] National Centre for Cell Science, Pune 411007, India [2] Institute for Genetics, Justus-Liebig University, Giessen D-35392, Germany
| | - Katharina Günther
- Institute for Genetics, Justus-Liebig University, Giessen D-35392, Germany
| | - Oliver Weth
- Institute for Genetics, Justus-Liebig University, Giessen D-35392, Germany
| | - Marek Bartkuhn
- Institute for Genetics, Justus-Liebig University, Giessen D-35392, Germany
| | | | | | - Rainer Renkawitz
- Institute for Genetics, Justus-Liebig University, Giessen D-35392, Germany
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le Maire A, Bourguet W. Retinoic acid receptors: structural basis for coregulator interaction and exchange. Subcell Biochem 2014; 70:37-54. [PMID: 24962880 DOI: 10.1007/978-94-017-9050-5_3] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the form of heterodimers with retinoid X receptors (RXRs), retinoic acid receptors (RARs) are master regulators of gene expression in humans and important drug targets. They act as ligand-dependent transcription factors that regulate a large variety of gene networks controlling cell growth, differentiation, survival and death. The biological functions of RARs rely on a dynamic series of coregulator exchanges controlled by ligand binding. Unliganded RARs exert a repressor activity by interacting with transcriptional corepressors which themselves serve as docking platforms for the recruitment of histone deacetylases that impose a higher order structure on chromatin which is not permissive to gene transcription. Upon ligand binding, the receptor undergoes conformational changes inducing corepressor release and the recruitment of coactivators with histone acetylase activities allowing chromatin decompaction and gene transcription. In the following, we review the structural determinants of the interaction between RAR and either type of coregulators both at the level of the individual receptor and in the context of the RAR-RXR heterodimers. We also discuss the molecular details of the fine tuning of these associations by the various pharmacological classes of ligands.
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Affiliation(s)
- Albane le Maire
- Inserm U1054, Centre de Biochimie Structurale, 29 rue de Navacelles, 34090, Montpellier, France,
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Abstract
Nuclear receptors are transcription factors that regulate gene expression through the ligand-controlled recruitment of a diverse group of proteins known as coregulators. Most nuclear receptor coregulators function in large multi-protein complexes that modify chromatin and thereby regulate the transcription of target genes. Structural and functional studies are beginning to reveal how these complexes are assembled bringing together multiple functionalities that mediate: recruitment to specific genomic loci through interaction with transcription factors; recruitment of enzymatic activities that either modify or remodel chromatin and targeting the complexes to their chromatin substrate. These activities are regulated by post-translational modifications, alternative splicing and small signalling molecules. This review focuses on our current understanding of coregulator complexes and aims to highlight the common principles that are beginning to emerge.
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Affiliation(s)
- Christopher J. Millard
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
| | - Peter J. Watson
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
| | - Louise Fairall
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
| | - John W.R. Schwabe
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
- Correspondence to:
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Burris TP, Solt LA, Wang Y, Crumbley C, Banerjee S, Griffett K, Lundasen T, Hughes T, Kojetin DJ. Nuclear receptors and their selective pharmacologic modulators. Pharmacol Rev 2013; 65:710-78. [PMID: 23457206 PMCID: PMC11060414 DOI: 10.1124/pr.112.006833] [Citation(s) in RCA: 180] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Nuclear receptors are ligand-activated transcription factors and include the receptors for steroid hormones, lipophilic vitamins, sterols, and bile acids. These receptors serve as targets for development of myriad drugs that target a range of disorders. Classically defined ligands that bind to the ligand-binding domain of nuclear receptors, whether they are endogenous or synthetic, either activate receptor activity (agonists) or block activation (antagonists) and due to the ability to alter activity of the receptors are often termed receptor "modulators." The complex pharmacology of nuclear receptors has provided a class of ligands distinct from these simple modulators where ligands display agonist/partial agonist/antagonist function in a tissue or gene selective manner. This class of ligands is defined as selective modulators. Here, we review the development and pharmacology of a range of selective nuclear receptor modulators.
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Affiliation(s)
- Thomas P Burris
- The Scripps Research Institute, 130 Scripps Way 2A1, Jupiter, FL 33458, USA.
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A novel 1297-1304delGCCTGCCA mutation in the exon 10 of the thyroid hormone receptor β gene causes resistance to thyroid hormone. ACTA ACUST UNITED AC 2013; 8:163-9. [PMID: 23315966 DOI: 10.1007/bf03260060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Resistance to the thyroid hormone (RTH) is an inherited syndrome of reduced tissue responsiveness to hormonal action caused by mutations located in the ligand-binding domain and adjacent hinge region of the thyroid hormone receptor β (TRβ) gene. PATIENT The patient in this study, a 42-year-old Caucasian male, came to medical attention because he experienced atrial fibrillation. Clinical evaluation showed a small and diffuse goiter and biochemical tests revealed markedly elevated concentrations of total T(4), total T(3), and free T(4), normal thyroid-stimulating hormone (TSH) values and slightly increased I(131) thyroid uptake at 24 hours. The thyroperoxidase, thyroglobulin, and TSH receptor antibodies were positive. He was treated with cabergoline plus methimazole. This treatment was stopped because of the inconsistent response, monotherapy with tri-iodothyroacetic acid (TRIAC) was then prescribed after molecular diagnosis confirmed RTH syndrome. METHODS The exons 9 and 10 of the TRβ gene, including splicing signals and the flanking intronic regions of each intron, were amplified with PCR. DNA sequences from each amplified fragment were performed with the Taq polymerase-based chain terminator method and using the specific TRβ forward and reverse primers. RESULTS Direct sequence analysis of the exons 9 and 10 of the TRβ gene revealed an eight basepair deletion, 1297-1304delGCCTGCCA in exon 10. The mutation produces a frameshift at amino acid 433 and introduces a stop codon TGA at position 461, 85 nucleotides downstream from deletion. This alteration was not detected in either the father or mother of the patient, suggesting a de novo mutation that was confirmed by DNA fingerprint analysis. CONCLUSIONS In the present study we have identified a novel sporadic mutation corresponding to 1297-1304delGCCTGCCA deletion in the activating function 2 (AF-2) region of TRβ. To our knowledge, this is the first time that the presence of a partial deletion of eight nucleotides in the TRβ has been reported.
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O'Malley BW, Malovannaya A, Qin J. Minireview: nuclear receptor and coregulator proteomics--2012 and beyond. Mol Endocrinol 2012; 26:1646-50. [PMID: 22745194 PMCID: PMC3458220 DOI: 10.1210/me.2012-1114] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 05/25/2012] [Indexed: 11/19/2022] Open
Abstract
The focus of our decade-long National Institutes of Health-sponsored NURSA Proteomics Atlas was to catalog and understand the composition of the steady-state interactome for all nuclear receptor coregulator complexes in a human cell. In this Perspective, we present a summary of the proteomics of coregulator complexes with examples of how one might use the NURSA data for future exploitation. The application of this information to the identification of the coregulator proteins that contribute to the molecular basis of polygenic diseases is emphasized.
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Affiliation(s)
- Bert W O'Malley
- Baylor College of Medicine, Department of Cellular Biology, One Baylor Plaza, Houston Texas 77030-3498, USA.
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Mavinakere MS, Powers JM, Subramanian KS, Roggero VR, Allison LA. Multiple novel signals mediate thyroid hormone receptor nuclear import and export. J Biol Chem 2012; 287:31280-97. [PMID: 22815488 PMCID: PMC3438959 DOI: 10.1074/jbc.m112.397745] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Thyroid hormone receptor (TR) is a member of the nuclear receptor superfamily that shuttles between the cytosol and nucleus. The fine balance between nuclear import and export of TR has emerged as a critical control point for modulating thyroid hormone-responsive gene expression; however, sequence motifs of TR that mediate shuttling are not fully defined. Here, we characterized multiple signals that direct TR shuttling. Along with the known nuclear localization signal in the hinge domain, we identified a novel nuclear localization signal in the A/B domain of thyroid hormone receptor α1 that is absent in thyroid hormone receptor β1 and inactive in the oncoprotein v-ErbA. Our prior studies showed that thyroid hormone receptor α1 exits the nucleus through two pathways, one dependent on the export factor CRM1 and the other CRM1-independent. Here, we identified three novel CRM1-independent nuclear export signal (NES) motifs in the ligand-binding domain as follows: a highly conserved NES in helix 12 (NES-H12) and two additional NES sequences spanning helix 3 and helix 6, respectively. Mutations predicted to disrupt the α-helical structure resulted in a significant decrease in NES-H12 activity. The high degree of conservation of helix 12 suggests that this region may function as a key NES in other nuclear receptors. Furthermore, our mutagenesis studies on NES-H12 suggest that altered shuttling of thyroid hormone receptor β1 may be a contributing factor in resistance to thyroid hormone syndrome. Taken together, our findings provide a detailed mechanistic understanding of the multiple signals that work together to regulate TR shuttling and transcriptional activity, and they provide important insights into nuclear receptor function in general.
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Affiliation(s)
- Manohara S Mavinakere
- Department of Biology, College of William and Mary, Williamsburg, Virginia 23187, USA
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Johnson AB, O'Malley BW. Steroid receptor coactivators 1, 2, and 3: critical regulators of nuclear receptor activity and steroid receptor modulator (SRM)-based cancer therapy. Mol Cell Endocrinol 2012; 348:430-9. [PMID: 21664237 PMCID: PMC3202666 DOI: 10.1016/j.mce.2011.04.021] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 04/04/2011] [Accepted: 04/22/2011] [Indexed: 01/17/2023]
Abstract
Coactivators are a diverse group of non-DNA binding proteins that induce structural changes in agonist-bound nuclear receptors (NRs) that are essential for NR-mediated transcriptional activation. Once bound, coactivators function to bridge enhancer binding proteins to the general transcription machinery, as well as to recruit secondary coactivators that modify promoter and enhancer chromatin in a manner permissive for transcriptional activation. In the following review article, we focus on one of the most in-depth studied families of coactivators, the steroid receptor coactivators (SRC) 1, 2, and 3. SRCs are widely implicated in NR-mediated diseases, especially in cancers, with the majority of studies focused on their roles in breast cancer. We highlight the relevant literature supporting the oncogenic activity of SRCs and their future as diagnostic and prognostic indicators. With much interest in the development of selective receptor modulators (SRMs), we focus on how these coactivators regulate the interactions between SRMs and their respective NRs; and, importantly, the influence that coactivators have on the functional output of SRMs. Furthermore, we speculate that coactivator-specific inhibitors could provide powerful, all-encompassing treatments that target multiple modes of oncogenic regulation in cancers resistant to typical anti-endocrine treatments.
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Affiliation(s)
- Amber B Johnson
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, United States
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Ibhazehiebo K, Iwasaki T, Kimura-Kuroda J, Miyazaki W, Shimokawa N, Koibuchi N. Disruption of thyroid hormone receptor-mediated transcription and thyroid hormone-induced Purkinje cell dendrite arborization by polybrominated diphenyl ethers. ENVIRONMENTAL HEALTH PERSPECTIVES 2011; 119:168-75. [PMID: 20870570 PMCID: PMC3040602 DOI: 10.1289/ehp.1002065] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 09/22/2010] [Indexed: 05/03/2023]
Abstract
BACKGROUND Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants and are becoming a ubiquitous environmental contaminant. Adverse effects in the developing brain are of great health concern. OBJECTIVE We investigated the effect of PBDEs/hydroxylated PBDEs (OH-PBDEs) on thyroid hormone (TH) receptor (TR)-mediated transcription and on TH-induced dendrite arborization of cerebellar Purkinje cells. METHODS We examined the effect of PBDEs/OH-PBDEs on TR action using a transient transfection-based reporter gene assay. TR-cofactor binding was studied by the mammalian two-hybrid assay, and TR-DNA [TH response element (TRE)] binding was examined by the liquid chemiluminescent DNA pull-down assay. Chimeric receptors generated from TR and glucocorticoid receptor (GR) were used to identify the functional domain of TR responsible for PBDE action. The change in dendrite arborization of the Purkinje cell in primary culture of newborn rat cerebellum was also examined. RESULTS Several PBDE congeners suppressed TR-mediated transcription. The magnitude of suppression correlated with that of TR-TRE dissociation. PBDEs suppressed transcription of chimeric receptors containing the TR DNA binding domain (TR-DBD). We observed no such suppression with chimeras containing GR-DBD. In the cerebellar culture, PBDE significantly suppressed TH-induced Purkinje cell dendrite arborization. CONCLUSIONS Several PBDE congeners may disrupt the TH system by partial dissociation of TR from TRE acting through TR-DBD and, consequently, may disrupt normal brain development.
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Affiliation(s)
- Kingsley Ibhazehiebo
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Toshiharu Iwasaki
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Maebashi, Japan
- Address correspondence to T. Iwasaki, Department of Integrative Physiology, Division of Biological Regulations, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan. Telephone: 81-27-220-7923. Fax: 81-27-220-7926. E-mail:
| | - Junko Kimura-Kuroda
- Department of Developmental Morphology, Tokyo Metropolitan Institute for Neuroscience, Tokyo, Japan
| | - Wataru Miyazaki
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Maebashi, Japan
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Noriaki Shimokawa
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Noriyuki Koibuchi
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Maebashi, Japan
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Abstract
The three members of the p160 family of steroid receptor coactivators (SRC-1, SRC-2, and SRC-3) steer the functional output of numerous genetic programs and serve as pleiotropic rheostats for diverse physiological processes. Since their discovery ∼15 years ago, the extraordinary sum of examination of SRC function has shaped the foundation of our knowledge for the now 350+ coregulators that have been identified to date. In this perspective, we retrace our steps into the field of coregulators and provide a summary of selected seminal work that helped define the SRCs as masters of systems biology.
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Affiliation(s)
- Brian York
- From the Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Bert W. O'Malley
- From the Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030
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Buranapramest M, Chakravarti D. Chromatin remodeling and nuclear receptor signaling. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 87:193-234. [PMID: 20374705 DOI: 10.1016/s1877-1173(09)87006-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Nuclear receptors (NRs) constitute a large family of ligand-dependent transcription factors that play key roles in development, differentiation, metabolism, and homeostasis. They participate in these processes by coordinating and regulating the expression of their target genes. The eukaryotic genome is packaged as chromatin and is generally inhibitory to the process of transcription. NRs overcome this barrier by recruiting two classes of chromatin remodelers, histone modifying enzymes and ATP-dependent chromatin remodelers. These remodelers alter chromatin structure at target gene promoters by posttranslational modification of histone tails and by disrupting DNA-histone interactions, respectively. In the presence of ligand, NRs promote transcription by recruiting remodeling enzymes that increase promoter accessibility to the basal transcription machinery. In the absence of ligand a subset of NRs recruit remodelers that establish and maintain a closed chromatin environment, to ensure efficient gene silencing. This chapter reviews the chromatin remodeling enzymes associated with NR gene control, with an emphasis on the mechanisms of NR-mediated repression.
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Affiliation(s)
- Manop Buranapramest
- Division of Reproductive Biology Research, Department of Obstetrics and Gynecology, Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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22
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Sun H, Shen OX, Wang XR, Zhou L, Zhen SQ, Chen XD. Anti-thyroid hormone activity of bisphenol A, tetrabromobisphenol A and tetrachlorobisphenol A in an improved reporter gene assay. Toxicol In Vitro 2009; 23:950-4. [DOI: 10.1016/j.tiv.2009.05.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 04/22/2009] [Accepted: 05/10/2009] [Indexed: 10/20/2022]
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Han SJ, Lonard DM, O'Malley BW. Multi-modulation of nuclear receptor coactivators through posttranslational modifications. Trends Endocrinol Metab 2009; 20:8-15. [PMID: 19019695 PMCID: PMC3642869 DOI: 10.1016/j.tem.2008.10.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 10/02/2008] [Accepted: 10/03/2008] [Indexed: 01/23/2023]
Abstract
Nuclear receptor (NR) coactivators are recruited to DNA by NRs, potentiating NR-dependent gene transcription. To obtain the complexity of NR-mediated gene regulation with a finite number of coactivators, the molecular properties of coactivators are dynamically modulated by posttranslational modifications (PTMs) in response to external stimuli. PTMs can regulate the molecular interactions of coactivators with transcription factors and other coactivators, in addition to their cellular location, protein stability, conformation and enzymatic activity. Therefore, dynamic regulation of the molecular properties of coactivators by PTMs allows for the complexity of NR-dependent gene expression and influences the regulation of NR-mediated physiological processes. This review focuses on recent progress in our understanding of how coactivator PTMs influence NR-mediated gene transcription and addresses their biological relevance.
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Affiliation(s)
- Sang Jun Han
- Department of Molecular and Cellular Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, Texas 77030, USA
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24
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Sun H, Shen OX, Xu XL, Song L, Wang XR. Carbaryl, 1-naphthol and 2-naphthol inhibit the beta-1 thyroid hormone receptor-mediated transcription in vitro. Toxicology 2008; 249:238-42. [PMID: 18584933 DOI: 10.1016/j.tox.2008.05.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 05/13/2008] [Accepted: 05/14/2008] [Indexed: 11/30/2022]
Abstract
Effects of pesticides on the function of thyroid have attracted lots of attention because thyroid hormones (THs) play a major role in mammalian brain development. In order to screen for compounds that acted on the thyroid hormone receptor (TR) signaling pathway, we transiently transfected the vector pGal4-L-TRbeta1 (Gal4 DBD fused to hTRbeta1 LBD) and Gal4-responsive luciferase reporter pUAS-tk-Luc into HepG2 cell, developing a reporter gene assay which showed good response to triiodothyronine (T3) and thyroxine (T4) with the median effective concentration (EC(50)) of 0.46 and 25.53 nM, respectively. Bisphenol A exhibited weak anti-thyroid hormone activity with median inhibitory concentration (IC(50)) value of 6.45 x 10(-5)M. The assay showed acceptable repeatability to T3 with intra coefficient of variability (CV) of 5.9% and inter CV of 11.7%. Carbaryl, 1-naphthol (1-NAP) and 2-naphthol (2-NAP) were tested for their agonist and antagonist activities. As a result, we found that all the three related chemicals possessed TR antagonist activity and none of them showed the agonist activity. These results further indicated that TR might be the targets of industrial chemicals. And this assay provided a useful tool for investigating the effects of environment chemicals on thyoid function.
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Affiliation(s)
- Hong Sun
- Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing, China
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25
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Chaudhuri G. Nuclear receptors and female reproduction: a tale of 3 scientists, Jensen, Gustafsson, and O'Malley. Reprod Sci 2008; 15:110-20. [PMID: 18276948 DOI: 10.1177/1933719108314516] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Work on the estrogen receptor and glucocorticoid receptor laid the foundation for the discovery of a family of receptors known as the nuclear receptors. Discovery of these receptors has expanded our understanding of many hormonal and nonhormonal substances, which act through the nuclear receptors. These receptors are actually ligand-binding intracellular transcription factors, which induce nuclear expression of specific mRNAs, leading to synthesis of specific proteins with biological activity. This review for the benefit of gynecologists and reproductive physiologists focuses on the work of 3 scientists who were pioneers in the work on the estrogen, glucocorticoid, and progesterone receptors, which has had a major impact on our understanding of reproductive physiology and on the field of nuclear receptors.
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Affiliation(s)
- Gautam Chaudhuri
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at the University of California, Los Angeles, CA, USA.
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26
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Lonard DM, O'malley BW. Nuclear receptor coregulators: judges, juries, and executioners of cellular regulation. Mol Cell 2007; 27:691-700. [PMID: 17803935 DOI: 10.1016/j.molcel.2007.08.012] [Citation(s) in RCA: 349] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In a little more than 10 years, nuclear receptor (NR) coregulators (coactivators and corepressors) have contributed to our present realization that a great level of sophistication exists in transcriptional regulation. Here, we discuss the implications of coregulators as versatile regulatory agents, influencing not only transcriptional initiation but also elongation, splicing, and translation. In addition to this, there is an increasing recognition that they also regulate a variety of biological processes outside of the nucleus. An important concept that we wish to emphasize is that coregulators are both targets and propagators of posttranslational modification (PTM) codes. This underlies a sophisticated epigenetic regulatory scheme from which a complex and dynamic mammalian phenotype emanates.
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Affiliation(s)
- David M Lonard
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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27
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Abstract
Nuclear receptor (NR) coregulators (coactivators and corepressors) are essential elements in regulating nuclear receptor-mediated transcription. In a little more than a decade since their discovery, these proteins have been studied mechanistically and reveal that the regulation of transcription is a highly controlled and complex process. Because of their central role in regulating NR-mediated transcription and in coordinating intercompartmental metabolic processes, disruptions in coregulator biology can lead to pathological states. To date, the extent to which they are involved in human disease has not been widely appreciated. In a complete literature survey, we have identified nearly 300 distinct coregulators, revealing that a great variety of enzymatic and regulatory capabilities exist for NRs to regulate transcription and other cellular events. Here, we substantiate that coregulators are broadly implicated in human pathological states and will be of growing future interest in clinical medicine.
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Affiliation(s)
- David M Lonard
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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28
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Refetoff S, Dumitrescu AM. Syndromes of reduced sensitivity to thyroid hormone: genetic defects in hormone receptors, cell transporters and deiodination. Best Pract Res Clin Endocrinol Metab 2007; 21:277-305. [PMID: 17574009 DOI: 10.1016/j.beem.2007.03.005] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
At least six major steps are required for secreted thyroid hormone (TH) to exert its action on target tissues. Mutations interfering with three of these steps have been so far identified. The first recognized defect, which causes resistance to TH, involves the TH receptor beta gene and has been given the acronym RTH. Occurring in approximately 1 per 40,000 newborns, more than 1000 affected subjects, from 339 families, have been identified. The gene defect remains unknown in 15% of subjects with RTH. Two novel syndromes causing reduced sensitivity to TH were recently identified. One, producing severe psychomotor defects in > 100 males from 26 families, is caused by mutations in the cell-membrane transporter of TH, MCT8; the second, affecting the intracellular metabolism of TH in four individuals from two families, is caused by mutations in the SECISBP2 gene, which is required for the synthesis of selenoproteins, including TH deiodinases.
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Affiliation(s)
- Samuel Refetoff
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
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29
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Germain P, Staels B, Dacquet C, Spedding M, Laudet V. Overview of nomenclature of nuclear receptors. Pharmacol Rev 2007; 58:685-704. [PMID: 17132848 DOI: 10.1124/pr.58.4.2] [Citation(s) in RCA: 441] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nuclear receptor pharmacology has, to a certain extent, led the way, compared with other receptor systems, in the appreciation that ligands may exert very diverse pharmacology, based on their individual chemical structure and the allosteric changes induced in the receptor/accessory protein complex. This can lead to very selective pharmacological effects, which may not necessarily be predicted from the experience with other agonists/partial agonists/antagonists. If this is the case, then drug discovery may be back to drug-specific pharmacology (where each drug may have an original profile), rather than specific-drug pharmacology (where agents specific for a receptor have a distinct profile). As functional selectivity is indeed a crucial mechanism to be considered when going through the drug discovery development process, then initial screens using reconstituted systems may not show the appropriate pharmacology, simply because the required stoichiometry of corepressors and coactivators may not be present to select the best compounds; therefore, multiple effector systems are necessary to screen for differential activation, and, even then, screening with in vivo pathophysiological models may ultimately be required for the selection process-a massive but necessary task for pharmacologists. Thus, the characterization of nuclear receptors and their associated proteins and the ligands that interact with them will remain a challenge to pharmacologists.
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Affiliation(s)
- Pierre Germain
- Department of Cell Biology and Signal Transduction, Institut de Genetique et de Biologie Moleculaire et Cellulaire (IGBMC), 1 rue Laurent Fries, BP 10142, 67404 Illkirch Cedex, France.
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30
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Affiliation(s)
- Bert W O'Malley
- Baylor College of Medicine, Department of Cell Biology, 1 Baylor Plaza, Houston, Texas 77030, USA.
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31
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Nascimento AS, Dias SMG, Nunes FM, Aparício R, Ambrosio ALB, Bleicher L, Figueira ACM, Santos MAM, de Oliveira Neto M, Fischer H, Togashi M, Craievich AF, Garratt RC, Baxter JD, Webb P, Polikarpov I. Structural Rearrangements in the Thyroid Hormone Receptor Hinge Domain and Their Putative Role in the Receptor Function. J Mol Biol 2006; 360:586-98. [PMID: 16781732 DOI: 10.1016/j.jmb.2006.05.008] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 04/12/2006] [Accepted: 05/03/2006] [Indexed: 11/21/2022]
Abstract
The thyroid hormone receptor (TR) D-domain links the ligand-binding domain (LBD, EF-domain) to the DNA-binding domain (DBD, C-domain), but its structure, and even its existence as a functional unit, are controversial. The D domain is poorly conserved throughout the nuclear receptor family and was originally proposed to comprise an unfolded hinge that facilitates rotation between the LBD and the DBD. Previous TR LBD structures, however, have indicated that the true unstructured region is three to six amino acid residues long and that the D-domain N terminus folds into a short amphipathic alpha-helix (H0) contiguous with the DBD and that the C terminus of the D-domain comprises H1 and H2 of the LBD. Here, we solve structures of TR-LBDs in different crystal forms and show that the N terminus of the TRalpha D-domain can adopt two structures; it can either fold into an amphipathic helix that resembles TRbeta H0 or form an unstructured loop. H0 formation requires contacts with the AF-2 coactivator-binding groove of the neighboring TR LBD, which binds H0 sequences that resemble coactivator LXXLL motifs. Structural analysis of a liganded TR LBD with small angle X-ray scattering (SAXS) suggests that AF-2/H0 interactions mediate dimerization of this protein in solution. We propose that the TR D-domain has the potential to form functionally important extensions of the DBD and LBD or unfold to permit TRs to adapt to different DNA response elements. We also show that mutations of the D domain LXXLL-like motif indeed selectively inhibit TR interactions with an inverted palindromic response element (F2) in vitro and TR activity at this response element in cell-based transfection experiments.
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Affiliation(s)
- Alessandro S Nascimento
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São Carlense, 400 CEP 13560-970 São Carlos, SP, Brazil
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Brackertz M, Gong Z, Leers J, Renkawitz R. p66alpha and p66beta of the Mi-2/NuRD complex mediate MBD2 and histone interaction. Nucleic Acids Res 2006; 34:397-406. [PMID: 16415179 PMCID: PMC1331983 DOI: 10.1093/nar/gkj437] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Mi-2/NuRD complex is a multi-subunit protein complex with enzymatic activities involving chromatin remodeling and histone deacetylation. Targeting of Mi-2/NuRD to methylated CpG sequences mediates gene repression. The function of p66alpha and of p66beta within the multiple subunits has not been addressed. Here, we analyzed the in vivo function and binding of both p66-paralogs. Both factors function in synergy, since knocking-down p66alpha affects the repressive function of p66beta and vice versa. Both proteins interact with MBD2 functionally and biochemically. Mutation of a single amino acid of p66alpha abolishes in vivo binding to MBD2 and interferes with MBD2-mediated repression. This loss of binding results in a diffuse nuclear localization in contrast to wild-type p66alpha that shows a speckled nuclear distribution. Furthermore, wild-type subnuclear distribution of p66alpha and p66beta depends on the presence of MBD2. Both proteins interact with the tails of all octamer histones in vitro, and acetylation of histone tails interferes with p66 binding. The conserved region 2 of p66alpha is required for histone tail interaction as well as for wild-type subnuclear distribution. These results suggest a two-interaction forward feedback binding mode, with a stable chromatin association only after deacetylation of the histones has occurred.
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Affiliation(s)
| | | | | | - Rainer Renkawitz
- To whom correspondence should be addressed. Tel: +49 641 99 35460; Fax: +49 641 99 35469;
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Abstract
The O'Malley laboratory first showed that estrogen and progesterone act in the nucleus to stimulate synthesis of specific mRNAs (ovalbumin and avidin), coding for their respective inducible proteins. The overall molecular pathway of steroid-receptor-DNA-mRNA-protein-function was then established and provided a coherent foundation for future studies of the impact of estrogen and progesterone receptors on endocrine tissue development, adult function, and in pathologies such as cancer. The lab group went on to: biochemically demonstrate ligand-induced conformational activation of progesterone and estrogen receptors, discover the concept of ligand-independent activation of steroid receptors, discover key steroid receptor coactivator intermediary coactivators for receptor function, and define the role of coactivators/corepressors in selective receptor modulator drug action and in cell homeostasis. This body of work advanced our molecular understanding of the critical role of steroid hormones in normal and abnormal physiology and also generated a base of scientific knowledge that served to further modern hormonal therapy and disease management.
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Affiliation(s)
- Bert W O'Malley
- Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
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Abstract
Nuclear receptors require coactivator binding in order to activate transcription of their cognate target genes. Ligands regulate nuclear receptor (NR)-mediated recruitment of coactivators by binding to the ligand-binding domain of the receptor and inducing a conformational change allowing for recognition of a specific motif contained within the coactivator protein. This motif is known as the NR box or LXXLL (where L is leucine and X is any amino acid) domain. Here, we review the discovery of the domain as well as its characterization.
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Affiliation(s)
- R S Savkur
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA
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35
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Moehren U, Dressel U, Reeb CA, Väisänen S, Dunlop TW, Carlberg C, Baniahmad A. The highly conserved region of the co-repressor Sin3A functionally interacts with the co-repressor Alien. Nucleic Acids Res 2004; 32:2995-3004. [PMID: 15173382 PMCID: PMC434429 DOI: 10.1093/nar/gkh621] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Sin3 proteins are evolutionarily conserved co-repressors (CoR) that function as mediators of gene repression for a variety of transcriptional silencers. The paired amphipathic helices of Sin3A were identified and studied as protein-protein interacting domains. Previously we have shown the interaction of Sin3A with the CoR Alien in vivo and in vitro. Here, we show that Alien and Sin3A reside together in vivo with the vitamin D3 receptor on the human 24-hydroxylase (CYP24) promoter containing vitamin D3 response elements by chromatin immunoprecipitation. We delineated and characterized the interaction domains of Sin3A with Alien. Interestingly, the highly conserved region (HCR) of Sin3A, which has not yet been functionally characterized, interacts with Alien. The HCR encompasses only 134 amino acids, shares more than 80% identity with Sin3B and binds to the N-terminus of Alien, which harbours a transferable silencing function. Functionally, co-expression of Sin3A enhances Alien-mediated gene repression and overexpression of the HCR alone leads to the inhibition of Alien-mediated repression and to the induction of the endogenous CYP24 promoter. Our results therefore indicate a novel functional role of the Sin3 HCR and give novel insights into Alien-mediated gene repression.
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Affiliation(s)
- Udo Moehren
- Genetic Institute, Justus-Liebig-University, Heinrich-Buff-Ring 58-62, D-35392 Giessen, Germany
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Sánchez Zalabardo D, Rosell Costa D, Honorato Cia B, Rioja Zuazu J, Regojo Balboa JM, Fernández Montero JM, López Ferrandis J, Robles García JE, Zudaire Bergera JJ, García Foncillas J, Berián Polo JM. [Mutations of the androgen receptor gene in patients with clinically localized adenocarcinoma of the prostate]. Actas Urol Esp 2004; 28:221-9. [PMID: 15141419 DOI: 10.1016/s0210-4806(04)73063-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
UNLABELLED The aim of this study was to detect mutations in the human androgen receptor gene in radical prostatectomy specimens. MATERIAL AND METHODS The genomic sequence was realized in 67 radical prostatectomy specimens. The mean age was 64 years old. The PSA median was 15 ng/ml. TNM 1997: 34.3% were T1 and 65.7% T2. Genomic sequence: 1. Radical prostatectomy specimens desparaffitation. 2. Extraction of the DNA 3. DNA amplification. 4. Automatic genome sequence. 5. Comparison with Gene-Bank. RESULTS 16.7% of the specimens were mutated. The most frequent mutation was the punctual mutation. The exon most frequent mutated was exon 1.
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Affiliation(s)
- D Sánchez Zalabardo
- Departamento de Urología, Clínica Universitaria, Universidad de Navarra, Pamplona
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Abstract
Nuclear receptors (also known as nuclear hormone receptors) are hormone-regulated transcription factors that control many important physiological and developmental processes in animals and humans. Defects in receptor function result in disease. The diverse biological roles of these receptors reflect their surprisingly versatile transcriptional properties, with many receptors possessing the ability to both repress and activate target gene expression. These bipolar transcriptional properties are mediated through the interactions of the receptors with two distinct classes of auxiliary proteins: corepressors and coactivators. This review focuses on how corepressors work together with nuclear receptors to repress gene transcription in the normal organism and on the aberrations in this process that lead to neoplasia and endocrine disorders. The actions of coactivators and the contributions of the same corepressors to the functions of nonreceptor transcription factors are also touched on.
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Affiliation(s)
- Martin L Privalsky
- Section of Microbiology, Division of Biological Sciences, University of California, Davis, California 95616, USA.
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Kinyamu HK, Archer TK. Modifying chromatin to permit steroid hormone receptor-dependent transcription. ACTA ACUST UNITED AC 2004; 1677:30-45. [PMID: 15020043 DOI: 10.1016/j.bbaexp.2003.09.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2003] [Revised: 09/24/2003] [Accepted: 09/24/2003] [Indexed: 02/07/2023]
Abstract
Lipophilic hormones, including steroids, exert their physiological effects through binding to high-affinity superfamily of steroid hormone receptor (SR) proteins that function as ligand-dependent DNA binding transcription factors. To date, SR proteins are among a few transcription factors shown to directly interact with higher order chromatin structures to regulate gene expression. To perturb chromatin, SRs employ enzymatic multicomplexes that can either remodel or modify chromatin. Here we examine the current state of knowledge concerning multicomplex chromatin remodeling/modification machines and SR-dependent transcription. We will focus on the role of these protein-protein and chromatin-protein interactions in vivo with the MMTV promoter as a primary model. In addition, we discuss emerging evidence implicating chaperone proteins and proteasome degradation machinery in SR-mediated gene regulation within chromatin.
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Affiliation(s)
- H Karimi Kinyamu
- Chromatin and Gene Expression Section, Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, National Institutes of Health, 111 Alexander Drive, PO Box 12233 (MD E4-06), Research Triangle Park, NC 27709, USA
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39
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Nawaz Z, O'Malley BW. Urban Renewal in the Nucleus: Is Protein Turnover by Proteasomes Absolutely Required for Nuclear Receptor-Regulated Transcription? Mol Endocrinol 2004; 18:493-9. [PMID: 14673136 DOI: 10.1210/me.2003-0388] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
AbstractThe importance of the ubiquitin proteasome pathway in higher eukaryotes has been well established in cell cycle regulation, signal transduction, and cell differentiation, but has only recently been linked to nuclear hormone receptor-regulated gene transcription. Characterization of a number of ubiquitin proteasome pathway enzymes as coactivators and observations that several nuclear receptors are ubiquitinated and degraded in the course of their nuclear activities provide evidence that ubiquitin proteasome-mediated protein degradation plays an integral role in eukaryotic transcription. In addition to receptors, studies have revealed that coactivators are ubiquitinated and degraded via the proteasome. The notion that the ubiquitin proteasome pathway is involved in gene transcription is further strengthened by the fact that ubiquitin proteasome pathway enzymes are recruited to the promoters of target genes and that proteasome-dependent degradation of nuclear receptors is required for efficient transcriptional activity. These findings suggest that protein degradation is coupled with nuclear receptor coactivation activity. It is possible that the ubiquitin proteasome pathway modulates transcription by promoting remodeling and turnover of the nuclear receptor-transcription complex. In this review, we discus the possible role of the ubiquitin proteasome pathway in nuclear hormone receptor-regulated gene transcription.
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Affiliation(s)
- Zafar Nawaz
- Cancer Center, Creighton University, Omaha, Nebraska 68178, USA
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40
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Smith CL, O'Malley BW. Coregulator function: a key to understanding tissue specificity of selective receptor modulators. Endocr Rev 2004; 25:45-71. [PMID: 14769827 DOI: 10.1210/er.2003-0023] [Citation(s) in RCA: 640] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Ligands for the nuclear receptor superfamily control many aspects of biology, including development, reproduction, and homeostasis, through regulation of the transcriptional activity of their cognate receptors. Selective receptor modulators (SRMs) are receptor ligands that exhibit agonistic or antagonistic biocharacter in a cell- and tissue context-dependent manner. The prototypical SRM is tamoxifen, which as a selective estrogen receptor modulator, can activate or inhibit estrogen receptor action. SRM-induced alterations in the conformation of the ligand-binding domains of nuclear receptors influence their abilities to interact with other proteins, such as coactivators and corepressors. It has been postulated, therefore, that the relative balance of coactivator and corepressor expression within a given target cell determines the relative agonist vs. antagonist activity of SRMs. However, recent evidence reveals that the cellular environment also plays a critical role in determining SRM biocharacter. Cellular signaling influences the activity and subcellular localization of coactivators and corepressors as well as nuclear receptors, and this contributes to gene-, cell-, and tissue-specific responses to SRM ligands. Increased understanding of the effect of cellular environment on nuclear receptors and their coregulators has the potential to open the field of SRM discovery and research to many members of the nuclear receptor superfamily.
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Affiliation(s)
- Carolyn L Smith
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
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41
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Savkur RS, Bramlett KS, Clawson D, Burris TP. Pharmacology of nuclear receptor-coregulator recognition. VITAMINS AND HORMONES 2004; 68:145-83. [PMID: 15193454 DOI: 10.1016/s0083-6729(04)68005-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The nuclear receptor (NR) superfamily comprises approximately 50 members that are responsible for regulating a number of physiologic processes in humans, including metabolism, homeostasis, and reproduction. Included in the superfamily are the receptors for steroids, lipophilic vitamins, bile acids, retinoids, and various fatty acids. NRs exert their action as transcription factors that directly bind to the promoters of target genes and regulate their rate of transcription. To modulate transcription, however, NRs must recruit a number of accessory coregulators known as corepressors and coactivators. These coregulators harbor a variety of activities, such as the ability to modify chromatin structure, interact with basal transcriptional machinery, and modify RNA splicing. Recent studies have revealed that the pharmacological characteristics of various NR ligands are regulated by their ability to modulate the coregulator interaction profile of an NR.
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Affiliation(s)
- Rajesh S Savkur
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA
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42
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Savkur RS, Wu Y, Bramlett KS, Wang M, Yao S, Perkins D, Totten M, Searfoss G, Ryan TP, Su EW, Burris TP. Alternative splicing within the ligand binding domain of the human constitutive androstane receptor. Mol Genet Metab 2003; 80:216-26. [PMID: 14567971 DOI: 10.1016/j.ymgme.2003.08.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The human constitutive androstane receptor (hCAR; NR1I3) is a member of the nuclear receptor superfamily. The activity of hCAR is regulated by a variety of xenobiotics including clotrimazole and acetaminophen metabolites. hCAR, in turn, regulates a number of genes responsible for xenobiotic metabolism and transport including several cytochrome P450s (CYP 2B5, 2C9, and 3A4) and the multidrug resistance-associated protein 2 (MRP2, ABCC2). Thus, hCAR is believed to be a mediator of drug-drug interactions. We identified two novel hCAR splice variants: hCAR2 encodes a receptor in which alternative splice acceptor sites are utilized resulting in a 4 amino acid insert between exons 6 and 7, and a 5 amino acid insert between 7 and 8, and hCAR3 encodes a receptor with exon 7 completely deleted resulting in a 39 amino acid deletion. Both hCAR2 and hCAR3 mRNAs are expressed in a pattern similar to the initially described MB67 (hCAR1) with some key distinctions. Although the levels of expression vary depending on the tissue examined, hCAR2 and hCAR3 contribute 6-8% of total hCAR mRNA in liver. Analysis of the activity of these variants indicates that both hCAR2 and hCAR3 lose the ability to heterodimerize with RXR and lack transactivation activity in cotransfection experiments where either full-length receptor or GAL4 DNA-binding domain/CAR ligand binding domain chimeras were utilized. Although the role of hCAR2 and hCAR3 is currently unclear, these additional splice variants may provide for increased diversity in terms of responsiveness to xenobiotics.
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Affiliation(s)
- Rajesh S Savkur
- Gene Regulation Research, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, IN 46285, USA
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Abstract
DAX1 encoded by NR0B1, when mutated, is responsible for X-linked adrenal hypoplasia congenita (AHC). AHC is due to failure of the adrenal cortex to develop normally and is fatal if untreated. When duplicated, this gene is associated with an XY sex-reversed phenotype. DAX1 expression is present during development of the steroidogenic hypothalamic-pituitary-adrenal-gonadal (HPAG) axis and persists into adult life. Despite recognition of the crucial role for DAX1, its function remains largely undefined. The phenotypes of patients and animal models are complex and not always in agreement. Investigations using cell lines have proved difficult to interpret, possibly reflecting cell line choices and their limited characterization. We will review the efforts of our group and others to identify appropriate cell lines for optimizing ex vivo analysis of NR0B1 function throughout development. We will examine the role of DAX1 and its network partners in development of the hypothalamic-pituitary-adrenal/gonadal axis (HPAG) using a variety of different types of investigations, including those in model organisms. This network analysis will help us to understand normal and abnormal development of the HPAG. In addition, these studies permit identification of candidate genes for human inborn errors of HPAG development.
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Perrotta S, Nobili B, Rossi F, Di Pinto D, Cucciolla V, Borriello A, Oliva A, Della Ragione F. Vitamin A and infancy. Biochemical, functional, and clinical aspects. VITAMINS AND HORMONES 2003; 66:457-591. [PMID: 12852263 DOI: 10.1016/s0083-6729(03)01013-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Vitamin A is a very intriguing natural compound. The molecule not only has a complex array of physiological functions, but also represents the precursor of promising and powerful new pharmacological agents. Although several aspects of human retinol metabolism, including absorption and tissue delivery, have been clarified, the type and amounts of vitamin A derivatives that are intracellularly produced remain quite elusive. In addition, their precise function and targets still need to be identified. Retinoic acids, undoubtedly, play a major role in explaining activities of retinol, but, recently, a large number of physiological functions have been attributed to different retinoids and to vitamin A itself. One of the primary roles this vitamin plays is in embryogenesis. Almost all steps in organogenesis are controlled by retinoic acids, thus suggesting that retinol is necessary for proper development of embryonic tissues. These considerations point to the dramatic importance of a sufficient intake of vitamin A and explain the consequences if intake of retinol is deficient. However, hypervitaminosis A also has a number of remarkable negative consequences, which, in same cases, could be fatal. Thus, the use of large doses of retinol in the treatment of some human diseases and the use of megavitamin therapy for certain chronic disorders as well as the growing tendency toward vitamin faddism should alert physicians to the possibility of vitamin overdose.
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Affiliation(s)
- Silverio Perrotta
- Department of Pediatric, Medical School, Second University of Naples, Naples, Italy
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45
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Lazar MA. Nuclear receptor corepressors. NUCLEAR RECEPTOR SIGNALING 2003; 1:e001. [PMID: 16604174 PMCID: PMC1402229 DOI: 10.1621/nrs.01001] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2003] [Accepted: 06/05/2003] [Indexed: 11/20/2022]
Abstract
The ability of NR LBDs to transfer repression function to a heterologous DNA binding domain, and the cross-squelching of repression by untethered LBDs, has suggested that repression is mediated by interactions with putative cellular corepressor proteins. The yeast-two hybrid screen for protein interactors has proven to be the key to the isolation and characterization of corepressors. This short review will focus on N-CoR and SMRT.
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Affiliation(s)
- Mitchell A Lazar
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, The Penn Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
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46
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Dostert A, Heinzel T. DNA-dependent cofactor selectivity of the glucocorticoid receptor. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2003:279-95. [PMID: 12355721 DOI: 10.1007/978-3-662-04660-9_15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- A Dostert
- Chemotherapeutisches Forschungsinstitut, Georg-Speyer-Haus, Paul-Ehrlich-Str. 42-44, 60594 Frankfurt/Main, Germany.
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47
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Gizard F, Lavallee B, DeWitte F, Teissier E, Staels B, Hum DW. The transcriptional regulating protein of 132 kDa (TReP-132) enhances P450scc gene transcription through interaction with steroidogenic factor-1 in human adrenal cells. J Biol Chem 2002; 277:39144-55. [PMID: 12101186 DOI: 10.1074/jbc.m205786200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The human P450scc gene is regulated by the tissue-specific orphan nuclear receptor, steroidogenic factor-1 (SF-1), which plays a key role in several physiologic processes including steroid synthesis, adrenal and gonadal development, and sexual differentiation. Several studies have demonstrated the interaction of SF-1 with different proteins. However, it is clear that additional factors not yet identified are involved with SF-1 to regulate different target genes. Recently, it was demonstrated that a novel transcriptional regulating protein of 132 kDa (TReP-132) regulates expression of the human P450scc gene. The overexpression of TReP-132 in adrenal cells increases the production of pregnenolone, which is associated with the activation of P450scc gene expression. Considering the colocalization of TReP-132 and SF-1 in steroidogenic tissues such as the adrenal and testis, and the presence of two putative LXXLL motifs in TReP-132 that can potentially interact with SF-1, the relationship between these two factors on the P450scc gene promoter was determined. The coexpression of SF-1 and TReP-132 in adrenal NCI-H295 cells cooperates to increase promoter activity. Pull-down experiments demonstrated the interaction between TReP-132 and SF-1, and this was further confirmed in intact cells by coimmunoprecipitation/Western blot and two-hybrid analyses. Deletions and mutations of the TReP-132 cDNA sequence demonstrate that SF-1 interaction requires the LXXLL motif found at the amino-terminal region of the protein. Also, the "proximal activation domain" and the "AF-2 hexamer" motif of SF-1 are involved in interaction with TReP-132. Consistent with previous studies showing interaction between CBP/p300 and SF-1 or TReP-132, the coexpression of these three proteins results in a synergistic effect on P450scc gene promoter activity. Taken together the results in this study identify a novel function of TReP-132 as a partner in a complex with SF-1 and CBP/p300 to regulate gene transcription involved in steroidogenesis.
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Affiliation(s)
- Florence Gizard
- Oncology and Molecular Endocrinology Research Center, Laval University, Québec GIK 7P4, Canada
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48
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Martin B, Schneider R, Janetzky S, Waibler Z, Pandur P, Kühl M, Behrens J, von der Mark K, Starzinski-Powitz A, Wixler V. The LIM-only protein FHL2 interacts with beta-catenin and promotes differentiation of mouse myoblasts. J Cell Biol 2002; 159:113-22. [PMID: 12370240 PMCID: PMC2173499 DOI: 10.1083/jcb.200202075] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
FHL2 is a LIM-domain protein expressed in myoblasts but down-regulated in malignant rhabdomyosarcoma cells, suggesting an important role of FHL2 in muscle development. To investigate the importance of FHL2 during myoblast differentiation, we performed a yeast two-hybrid screen using a cDNA library derived from myoblasts induced for differentiation. We identified beta-catenin as a novel interaction partner of FHL2 and confirmed the specificity of association by direct in vitro binding tests and coimmunoprecipitation assays from cell lysates. Deletion analysis of both proteins revealed that the NH2-terminal part of beta-catenin is sufficient for binding in yeast, but addition of the first armadillo repeat is necessary for binding FHL2 in mammalian cells, whereas the presence of all four LIM domains of FHL2 is needed for the interaction. Expression of FHL2 counteracts beta-catenin-mediated activation of a TCF/LEF-dependent reporter gene in a dose-dependent and muscle cell-specific manner. After injection into Xenopus embryos, FHL2 inhibited the beta-catenin-induced axis duplication. C2C12 mouse myoblasts stably expressing FHL2 show increased myogenic differentiation reflected by accelerated myotube formation and expression of muscle-specific proteins. These data imply that FHL2 is a muscle-specific repressor of LEF/TCF target genes and promotes myogenic differentiation by interacting with beta-catenin.
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Affiliation(s)
- Bernd Martin
- Institut der Anthropologie und Humangenetik für Biologen, Johann-Wolfgang-Goethe-Universität, 60323 Frankfurt, Germany
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49
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Imhof MO, Chatellard P, Mermod N. Comparative study and identification of potent eukaryotic transcriptional repressors in gene switch systems. J Biotechnol 2002; 97:275-85. [PMID: 12084483 DOI: 10.1016/s0168-1656(02)00104-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In mammalian cells, proper gene regulation is achieved by the complex interplay of transcription factors that activate or repress gene expression by binding to the regulatory regions of target promoters. While transcriptional activators have been extensively characterised and classified into functional groups, relatively little is known about the comparative strength and cell type-specificity of transcriptional repressors. Here, we have compared the ability of a series of eukaryotic repression domains to silence basal and activated transcription. A series of the most potent repression domains was further tested in the context of a gene therapy gene-switch system in various cell types. The results indicate that the analysed repression domains exert varying silencing activities in different promoter contexts. Furthermore, their potential for gene silencing varies also depending on the cellular context. When multimerised within one chimeric repressor protein, particular combinations of repressor domains were found to display synergistic repressing effects and efficient repression in a panel of cell lines. This approach thus allowed the identification of transcriptional repressors that are both potent and versatile in terms of cellular specificity as a basis for gene switch systems.
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Affiliation(s)
- Markus O Imhof
- Laboratory of Molecular Biotechnology, Center for Biotechnology UNIL-EPFL and Institute of Animal Biology, University of Lausanne, 1015, Lausanne, Switzerland
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50
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Schulz M, Eggert M, Baniahmad A, Dostert A, Heinzel T, Renkawitz R. RU486-induced glucocorticoid receptor agonism is controlled by the receptor N terminus and by corepressor binding. J Biol Chem 2002; 277:26238-43. [PMID: 12011091 DOI: 10.1074/jbc.m203268200] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glucocorticoid-induced gene transcription has been shown to be mediated by coactivators bound to the glucocorticoid receptor (GR). The glucocorticoid antagonist RU486 interferes with the steroid-mediated activation and can also exhibit partial agonist activity, a response in which corepressors have been implicated. Here we have shown that deletion of the N terminus of GR totally abolishes the agonist activity of RU486. Furthermore, we have demonstrated that corepressors bind directly to the RU486-bound GR as determined by glutathione S-transferase pull-down, mammalian two-hybrid assay, and coimmunoprecipitation. Fine mapping of the interaction regions within GR and the corepressor NCoR reveals a complex interaction profile that involves a number of domains in each protein. Notably, the N and the C termini of GR are both involved in corepressor binding. Thus, the N terminus of GR is a major determinant for RU486-dependent NCoR interaction as well as for RU486-mediated agonist activity.
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Affiliation(s)
- Martin Schulz
- Institute for Genetics, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 58-62, D-35392 Giessen, Germany
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