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Walter KM, Singh L, Singh V, Lein PJ. Investigation of NH3 as a selective thyroid hormone receptor modulator in larval zebrafish (Danio rerio). Neurotoxicology 2021; 84:96-104. [PMID: 33745965 DOI: 10.1016/j.neuro.2021.03.003] [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] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 03/07/2021] [Accepted: 03/15/2021] [Indexed: 11/17/2022]
Abstract
Thyroid hormones (THs) are essential for normal vertebrate development and diverse environmental chemicals are hypothesized to cause developmental toxicity by disrupting TH-mediated signaling. The larval zebrafish (Danio rerio) is an emerging in vivo model of developmental TH disruption; however, the effects of TR antagonism have not yet been studied in zebrafish. NH3, generally considered a potent and specific thyroid hormone receptor (TR) antagonist, has been used in rodents and Xenopus laevis to characterize phenotypes of TR antagonism. The objective of this study is to determine the effects of NH3 on endpoints previously determined to be TH-sensitive in larval zebrafish, specifically teratology and mortality, photomotor behavior, and mRNA expression of TH signaling genes. Zebrafish embryos were exposed to NH3 via static waterborne exposure at concentrations ranging from 0.001 to 10 μM beginning at 6 h post-fertilization (hpf) through 5 days post fertilization (dpf). Significant mortality and teratogenesis was observed at 3, 4, and 5 dpf in zebrafish exposed to NH3 at 10 μM. At concentrations that did not cause significant mortality, NH3 did not exert a consistent antagonistic effect on photomotor behavior assays or mRNA expression when administered alone or in the presence of exogenous T4. Rather, depending on the NH3 concentration and larval age NH3 decreased or increased swimming triggered by transition from light to dark. Similarly, inconsistent antagonistic and agonistic effects on mRNA expression of TH signaling genes were noted following treatment with NH3 alone. NH3 did inhibit T4 (30 nM)-induced gene expression; however, this was only consistently observed at a concentration of NH3 (10 μM) that also caused significant mortality. Collectively, these results suggest that NH3 does not act solely as a TR antagonist in larval zebrafish, but instead exhibits complex modulatory effects on TR activity. These data support the hypothesis that NH3 is a selective thyroid hormone receptor modulator. Further studies of NH3 interactions with the zebrafish thyroid hormone receptor are required to characterize the activity of NH3 in target tissues of the larval zebrafish at the molecular level, highlighting the importance of characterizing NH3 effects in specific models of TH-disruption to better interpret its actions in mechanistic screens of environmental chemicals for TH action.
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Affiliation(s)
- Kyla M Walter
- Department of Molecular Biosciences, University of California-Davis School of Veterinary Medicine, Davis, CA, 95616, United States.
| | - Latika Singh
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, United States.
| | - Vikrant Singh
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, United States.
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California-Davis School of Veterinary Medicine, Davis, CA, 95616, United States.
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2
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Monczor F, Chatzopoulou A, Zappia CD, Houtman R, Meijer OC, Fitzsimons CP. A Model of Glucocorticoid Receptor Interaction With Coregulators Predicts Transcriptional Regulation of Target Genes. Front Pharmacol 2019; 10:214. [PMID: 30930776 PMCID: PMC6425864 DOI: 10.3389/fphar.2019.00214] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 02/20/2019] [Indexed: 12/14/2022] Open
Abstract
Regulatory factors that control gene transcription in multicellular organisms are assembled in multicomponent complexes by combinatorial interactions. In this context, nuclear receptors provide well-characterized and physiologically relevant systems to study ligand-induced transcription resulting from the integration of cellular and genomic information in a cell- and gene-specific manner. Here, we developed a mathematical model describing the interactions between the glucocorticoid receptor (GR) and other components of a multifactorial regulatory complex controlling the transcription of GR-target genes, such as coregulator peptides. We support the validity of the model in relation to gene-specific GR transactivation with gene transcription data from A549 cells and in vitro real time quantification of coregulator-GR interactions. The model accurately describes and helps to interpret ligand-specific and gene-specific transcriptional regulation by the GR. The comprehensive character of the model allows future insight into the function and relative contribution of the molecular species proposed in ligand- and gene-specific transcriptional regulation.
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Affiliation(s)
- Federico Monczor
- Laboratorio de Farmacología de Receptores, Instituto de Investigaciones Farmacológicas, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Antonia Chatzopoulou
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
| | - Carlos Daniel Zappia
- Laboratorio de Farmacología de Receptores, Instituto de Investigaciones Farmacológicas, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - René Houtman
- PamGene International B.V., 's-Hertogenbosch, Netherlands
| | - Onno C Meijer
- Division of Endocrinology, Department of Internal Medicine, Leiden University Medical Centre, Leiden, Netherlands
| | - Carlos P Fitzsimons
- Neuroscience Collaboration, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
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Campbell DEK, Langlois VS. Expression of sf1 and dax-1 are regulated by thyroid hormones and androgens during Silurana tropicalis early development. Gen Comp Endocrinol 2018; 259:34-44. [PMID: 29107601 DOI: 10.1016/j.ygcen.2017.10.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 10/25/2017] [Accepted: 10/27/2017] [Indexed: 11/27/2022]
Abstract
Thyroid hormones (THs) and androgens have been shown to be extensively involved in sexual development; however, relatively little is known with regard to TH-related and androgenic actions in sex determination. We first established expression profiles of three sex-determining genes (sf1, dax-1, and sox9) during the embryonic development of Western clawed frogs (Silurana tropicalis). Transcripts of sf1 and sox9 were detected in embryos before the period in which embryonic transcription commences indicating maternal transfer, whereas dax-1 transcripts were not detected until later in development. To examine whether TH status affects sex-determining gene expression in embryonic S. tropicalis, embryos were exposed to co-treatments of iopanoic acid (IOP), thyroxine (T4), or triiodothyronine (T3) for 96 h. Expression profiles of TH receptors and deiodinases reflect inhibition of peripheral deiodinase activity by IOP and recovery by T3. Relevantly, elevated TH levels significantly increased the expression of sf1 and dax-1 in embryonic S. tropicalis. Further supporting TH-mediated regulation, examination of the presence and frequency of transcription factor binding sites in the putative promoter regions of sex-determining genes in S. tropicalis and rodent and fish models using in silico analysis also identified TH motifs in the putative promoter regions of sf1 and dax-1. Together these findings advocate that TH actions as early as the period of embryogenesis may affect gonadal fate in frogs. Mechanisms of TH and androgenic crosstalk in relation to the regulation of steroid-related gene expression were also investigated.
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Affiliation(s)
| | - Valerie S Langlois
- Biology Department, Queen's University, Kingston, ON Canada; Institut National de la recherche scientifique (INRS) - Centre Eau Terre Environnement (ETE), Quebec, QC, Canada; Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON Canada.
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4
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Kunz C, Schuldt-Lieb S, Gieseler H. Freeze-Drying From Organic Cosolvent Systems, Part 1: Thermal Analysis of Cosolvent-Based Placebo Formulations in the Frozen State. J Pharm Sci 2018; 107:887-896. [DOI: 10.1016/j.xphs.2017.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/31/2017] [Accepted: 11/01/2017] [Indexed: 11/28/2022]
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5
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Campos JLO, Doratioto TR, Videira NB, Ribeiro Filho HV, Batista FAH, Fattori J, Indolfo NDC, Nakahira M, Bajgelman MC, Cvoro A, Laurindo FRM, Webb P, Figueira ACM. Protein Disulfide Isomerase Modulates the Activation of Thyroid Hormone Receptors. Front Endocrinol (Lausanne) 2018; 9:784. [PMID: 30671024 PMCID: PMC6331412 DOI: 10.3389/fendo.2018.00784] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 12/12/2018] [Indexed: 12/30/2022] Open
Abstract
Thyroid hormone receptors (TRs) are responsible for mediating thyroid hormone (T3 and T4) actions at a cellular level. They belong to the nuclear receptor (NR) superfamily and execute their main functions inside the cell nuclei as hormone-regulated transcription factors. These receptors also exhibit so-called "non-classic" actions, for which other cellular proteins, apart from coregulators inside nuclei, regulate their activity. Aiming to find alternative pathways of TR modulation, we searched for interacting proteins and found that PDIA1 interacts with TRβ in a yeast two-hybrid screening assay. The functional implications of PDIA1-TR interactions are still unclear; however, our co-immunoprecipitation (co-IP) and fluorescence assay results showed that PDI was able to bind both TR isoforms in vitro. Moreover, T3 appears to have no important role in these interactions in cellular assays, where PDIA1 was able to regulate transcription of TRα and TRβ-mediated genes in different ways depending on the promoter region and on the TR isoform involved. Although PDIA1 appears to act as a coregulator, it binds to a TR surface that does not interfere with coactivator binding. However, the TR:PDIA1 complex affinity and activation are different depending on the TR isoform. Such differences may reflect the structural organization of the PDIA1:TR complex, as shown by models depicting an interaction interface with exposed cysteines from both proteins, suggesting that PDIA1 might modulate TR by its thiol reductase/isomerase activity.
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Affiliation(s)
- Jessica L. O. Campos
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research Energy and Materials (CNPEM), São Paulo, Brazil
- Graduation Program of Biosciences and Bioactive Products Technology, Institute of Biology, State University of Campinas (Unicamp), São Paulo, Brazil
| | - Tabata R. Doratioto
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research Energy and Materials (CNPEM), São Paulo, Brazil
- Graduation Program of Biosciences and Bioactive Products Technology, Institute of Biology, State University of Campinas (Unicamp), São Paulo, Brazil
| | - Natalia B. Videira
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research Energy and Materials (CNPEM), São Paulo, Brazil
- Graduation Program of Biosciences and Bioactive Products Technology, Institute of Biology, State University of Campinas (Unicamp), São Paulo, Brazil
| | - Helder V. Ribeiro Filho
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research Energy and Materials (CNPEM), São Paulo, Brazil
- Graduation Program of Biosciences and Bioactive Products Technology, Institute of Biology, State University of Campinas (Unicamp), São Paulo, Brazil
| | - Fernanda A. H. Batista
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research Energy and Materials (CNPEM), São Paulo, Brazil
| | - Juliana Fattori
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research Energy and Materials (CNPEM), São Paulo, Brazil
| | - Nathalia de C. Indolfo
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research Energy and Materials (CNPEM), São Paulo, Brazil
- Graduation Program of Biosciences and Bioactive Products Technology, Institute of Biology, State University of Campinas (Unicamp), São Paulo, Brazil
| | - Marcel Nakahira
- Institute of Chemistry (IQ), State University of Campinas (Unicamp), São Paulo, Brazil
| | - Marcio C. Bajgelman
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research Energy and Materials (CNPEM), São Paulo, Brazil
| | - Aleksandra Cvoro
- Genomic Medicine, The Methodist Hospital Research Institute, Houston, TX, United States
| | - Francisco R. M. Laurindo
- Vascular Biology Laboratory, Heart Institute (InCor), School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Paul Webb
- California Institute for Regenerative Medicine, Oakland, CA, United States
| | - Ana Carolina M. Figueira
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research Energy and Materials (CNPEM), São Paulo, Brazil
- *Correspondence: Ana Carolina M. Figueira
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Hernández-Puga G, Mendoza A, León-Del-Río A, Orozco A. Jab1 is a T2-dependent coactivator or a T3-dependent corepressor of TRB1-mediated gene regulation. J Endocrinol 2017; 232:451-459. [PMID: 28053002 DOI: 10.1530/joe-16-0485] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 01/04/2017] [Indexed: 12/14/2022]
Abstract
Thyroid hormones (THs) induce pleiotropic effects in vertebrates, mainly through the activation or repression of gene expression. These mechanisms involve thyroid hormone binding to thyroid hormone receptors, an event that is followed by the sequential recruitment of coactivator or corepressor proteins, which in turn modify the rate of transcription. In the present study, we looked for specific coregulators recruited by the long isoform of the teleostean thyroid hormone receptor beta 1 (L-Trb1) when bound to the bioactive TH, 3,5-T2 (T2). We found that jun activation domain-binding protein1 (Jab1) interacts with L-Trb1 + T2 complex. Using both the teleostean and human TRB1 isoforms, we characterized the Jab1-TRB1 by yeast two-hybrid, pull-down and transactivation assays. Our results showed that the TRB1-Jab1 interaction was ligand dependent and involved the single Jab1 nuclear receptor box, as well as the ligand-binding and N-terminal domains of TRB1. We also provide evidence of ligand-dependent, dual coregulatory properties of Jab1. Indeed, when T2 is bound to L-Trb1 or hTRB1, Jab1 acts as a coactivator of transcription, whereas it has corepressor activity when interacting with the T3-bound S-Trb1 or hTRB1. These mechanisms could explain some of the pleiotropic actions exerted by THs to regulate diverse biological processes.
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Affiliation(s)
- Gabriela Hernández-Puga
- Departamento de Neurobiología Celular y MolecularInstituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Arturo Mendoza
- Departamento de Neurobiología Celular y MolecularInstituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Alfonso León-Del-Río
- Programa de Investigación de Cáncer de Mama y Departamento de Biología Molecular y BiotecnologíaInstituto de Investigaciones Biomédicas, UNAM, México, Mexico
| | - Aurea Orozco
- Departamento de Neurobiología Celular y MolecularInstituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
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Fernández-Pernas P, Fafián-Labora J, Lesende-Rodriguez I, Mateos J, De la Fuente A, Fuentes I, De Toro Santos J, Blanco García F, Arufe MC. 3, 3', 5-triiodo-L-thyronine Increases In Vitro Chondrogenesis of Mesenchymal Stem Cells From Human Umbilical Cord Stroma Through SRC2. J Cell Biochem 2016; 117:2097-108. [PMID: 26869487 DOI: 10.1002/jcb.25515] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 02/09/2016] [Indexed: 02/05/2023]
Abstract
Our group focuses on the study of mesenchymal stem cells (MSCs) from human umbilical cord stroma or Warthońs jelly and their directed differentiation toward chondrocyte-like cells capable of regenerating damaged cartilage when transplanted into an injured joint. This study aimed to determine whether lactogenic hormone prolactin (PRL) or 3, 3', 5-triiodo-L-thyronine (T3), the active thyroid hormone, modulates chondrogenesis in our in vitro model of directed chondrogenic differentiation, and whether Wnt signalling is involved in this modulation. MSCs from human umbilical cord stroma underwent directed differentiation toward chondrocyte-like cells by spheroid formation. The addition of T3 to the chondrogenic medium increased the expression of genes linked to chondrogenesis like collagen type 2, integrin alpha 10 beta 1, and Sox9 measured by quantitative real time polymerase chain reaction (qRT-PCR) analysis. Levels of collagen type 2 and aggrecane analyzed by immunohistochemistry, and staining by Safranin O were increased after 14 days in spheroid culture with T3 compared to those without T3 or only with PRL. B-catenin, Frizzled, and GSK-3β gene expressions were significantly higher in spheroids cultured with chondrogenic medium (CM) plus T3 compared to CM alone after 14 days in culture. The increase of chondrogenic differentiation was inhibited when the cells were treated with T3 plus ML151, an inhibitor of the T3 steroid receptor. This work demonstrates, for first time, that T3 promotes differentiation towards chondrocytes-like cells in our in vitro model, that this differentiation is mediated by steroid receptor co-activator 2 (SRC2) and does not induce hypertrophy. J. Cell. Biochem. 117: 2097-2108, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Pablo Fernández-Pernas
- Grupo de Terapia Celular y Medicina Regenerativa (TCMR-CHUAC), CIBER-BBN/ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Departamento de Medicina, Facultade de Oza, Universidade da Coruña (UDC), As Xubias, 15006, A Coruña, Spain
| | - Juan Fafián-Labora
- Grupo de Terapia Celular y Medicina Regenerativa (TCMR-CHUAC), CIBER-BBN/ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Departamento de Medicina, Facultade de Oza, Universidade da Coruña (UDC), As Xubias, 15006, A Coruña, Spain
| | - Iván Lesende-Rodriguez
- Grupo de Terapia Celular y Medicina Regenerativa (TCMR-CHUAC), CIBER-BBN/ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Departamento de Medicina, Facultade de Oza, Universidade da Coruña (UDC), As Xubias, 15006, A Coruña, Spain
| | - Jesús Mateos
- Grupo de Proteómica-PBR2-ProteoRed/ISCIII-Servicio de Reumatologia, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Universidade da Coruña (UDC), As Xubias, 15006, A Coruña, España
| | - Alexandre De la Fuente
- Grupo de Terapia Celular y Medicina Regenerativa (TCMR-CHUAC), CIBER-BBN/ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Departamento de Medicina, Facultade de Oza, Universidade da Coruña (UDC), As Xubias, 15006, A Coruña, Spain
| | - Isaac Fuentes
- Grupo de Terapia Celular y Medicina Regenerativa (TCMR-CHUAC), CIBER-BBN/ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Departamento de Medicina, Facultade de Oza, Universidade da Coruña (UDC), As Xubias, 15006, A Coruña, Spain
| | - Javier De Toro Santos
- Grupo de Terapia Celular y Medicina Regenerativa (TCMR-CHUAC), CIBER-BBN/ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Departamento de Medicina, Facultade de Oza, Universidade da Coruña (UDC), As Xubias, 15006, A Coruña, Spain
| | - Fco Blanco García
- Grupo de Proteómica-PBR2-ProteoRed/ISCIII-Servicio de Reumatologia, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Universidade da Coruña (UDC), As Xubias, 15006, A Coruña, España
| | - María C Arufe
- Grupo de Terapia Celular y Medicina Regenerativa (TCMR-CHUAC), CIBER-BBN/ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Departamento de Medicina, Facultade de Oza, Universidade da Coruña (UDC), As Xubias, 15006, A Coruña, Spain
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8
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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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Tamijani SMS, Karimi B, Amini E, Golpich M, Dargahi L, Ali RA, Ibrahim NM, Mohamed Z, Ghasemi R, Ahmadiani A. Thyroid hormones: Possible roles in epilepsy pathology. Seizure 2015; 31:155-64. [PMID: 26362394 DOI: 10.1016/j.seizure.2015.07.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 07/26/2015] [Accepted: 07/27/2015] [Indexed: 11/16/2022] Open
Abstract
Thyroid hormones (THs) L-thyroxine and L-triiodothyronine, primarily known as metabolism regulators, are tyrosine-derived hormones produced by the thyroid gland. They play an essential role in normal central nervous system development and physiological function. By binding to nuclear receptors and modulating gene expression, THs influence neuronal migration, differentiation, myelination, synaptogenesis and neurogenesis in developing and adult brains. Any uncorrected THs supply deficiency in early life may result in irreversible neurological and motor deficits. The development and function of GABAergic neurons as well as glutamatergic transmission are also affected by THs. Though the underlying molecular mechanisms still remain unknown, the effects of THs on inhibitory and excitatory neurons may affect brain seizure activity. The enduring predisposition of the brain to generate epileptic seizures leads to a complex chronic brain disorder known as epilepsy. Pathologically, epilepsy may be accompanied by mitochondrial dysfunction, oxidative stress and eventually dysregulation of excitatory glutamatergic and inhibitory GABAergic neurotransmission. Based on the latest evidence on the association between THs and epilepsy, we hypothesize that THs abnormalities may contribute to the pathogenesis of epilepsy. We also review gender differences and the presumed underlying mechanisms through which TH abnormalities may affect epilepsy here.
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Affiliation(s)
| | - Benyamin Karimi
- Department of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Cheras, Kuala Lumpur, Malaysia
| | - Elham Amini
- Department of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Cheras, Kuala Lumpur, Malaysia
| | - Mojtaba Golpich
- Department of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Cheras, Kuala Lumpur, Malaysia
| | - Leila Dargahi
- NeuroBiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Raymond Azman Ali
- Department of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Cheras, Kuala Lumpur, Malaysia
| | - Norlinah Mohamed Ibrahim
- Department of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Cheras, Kuala Lumpur, Malaysia
| | - Zahurin Mohamed
- Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Rasoul Ghasemi
- Department of Physiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Abolhassan Ahmadiani
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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10
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Bellelli R, Castellone MD, Guida T, Limongello R, Dathan NA, Merolla F, Cirafici AM, Affuso A, Masai H, Costanzo V, Grieco D, Fusco A, Santoro M, Carlomagno F. NCOA4 transcriptional coactivator inhibits activation of DNA replication origins. Mol Cell 2014; 55:123-37. [PMID: 24910095 DOI: 10.1016/j.molcel.2014.04.031] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 03/31/2014] [Accepted: 04/28/2014] [Indexed: 11/19/2022]
Abstract
NCOA4 is a transcriptional coactivator of nuclear hormone receptors that undergoes gene rearrangement in human cancer. By combining studies in Xenopus laevis egg extracts and mouse embryonic fibroblasts (MEFs), we show here that NCOA4 is a minichromosome maintenance 7 (MCM7)-interacting protein that is able to control DNA replication. Depletion-reconstitution experiments in Xenopus laevis egg extracts indicate that NCOA4 acts as an inhibitor of DNA replication origin activation by regulating CMG (CDC45/MCM2-7/GINS) helicase. NCOA4(-/-) MEFs display unscheduled origin activation and reduced interorigin distance; this results in replication stress, as shown by the presence of fork stalling, reduction of fork speed, and premature senescence. Together, our findings indicate that NCOA4 acts as a regulator of DNA replication origins that helps prevent inappropriate DNA synthesis and replication stress.
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Affiliation(s)
- Roberto Bellelli
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy
| | - Maria Domenica Castellone
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy
| | - Teresa Guida
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy
| | - Roberto Limongello
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy
| | | | - Francesco Merolla
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy
| | - Anna Maria Cirafici
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy
| | - Andrea Affuso
- Animal Model Facility, Biogem s.c.a.r.l., 83031 Ariano Irpino, Avellino, Italy
| | - Hisao Masai
- Tokyo Metropolitan Institute of Medical Sciences, 156-8506 Tokyo, Japan
| | - Vincenzo Costanzo
- London Research Institute, Clare Hall Laboratories, Blanche Lane, South Mimms EN6 3LD, UK
| | - Domenico Grieco
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy
| | - Alfredo Fusco
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy
| | - Massimo Santoro
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy.
| | - Francesca Carlomagno
- Istituto di Endocrinologia ed Oncologia Sperimentale del CNR/Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II," 80131 Naples, Italy.
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11
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Flood DEK, Fernandino JI, Langlois VS. Thyroid hormones in male reproductive development: evidence for direct crosstalk between the androgen and thyroid hormone axes. Gen Comp Endocrinol 2013; 192:2-14. [PMID: 23524004 DOI: 10.1016/j.ygcen.2013.02.038] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 02/24/2013] [Accepted: 02/26/2013] [Indexed: 01/06/2023]
Abstract
Thyroid hormones (THs) exert a broad range of effects on development in vertebrate species, demonstrating connections in nearly every biological endocrine system. In particular, studies have shown that THs play a role in sexual differentiation and gonadal development in mammalian and non-mammalian species. There is considerable evidence that the effects of THs on reproductive development are mediated through the female hormonal axis; however, recent findings suggest a more direct crosstalk between THs and the androgen axis. These findings demonstrate that THs have considerable influence in the sexual ontogeny of male vertebrates, through direct interactions with select sex-determining-genes and regulation of gonadotropin production in the hypothalamus-pituitary-gonad axis. THs also regulate androgen biosynthesis and signaling through direct and indirect regulation of steroidogenic enzyme expression and activity. Novel promoter analysis presented in this work demonstrates the potential for direct and vertebrate wide crosstalk at the transcriptional level in mice (Mus musculus), Western clawed frogs (Silurana tropicalis) and medaka (Oryzias latipes). Cumulative evidence from previous studies; coupled with novel promoter analysis suggests mechanisms for a more direct crosstalk between the TH and male reproductive axes across vertebrate species.
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Affiliation(s)
- Diana E K Flood
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, ON, Canada; Biology Department, Queen's University, Kingston, ON, Canada.
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12
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Ren XM, Guo LH. Molecular toxicology of polybrominated diphenyl ethers: nuclear hormone receptor mediated pathways. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2013; 15:702-8. [PMID: 23467608 DOI: 10.1039/c3em00023k] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are used in large quantities as flame retardant additives in commercial products. Bio-monitoring data show that PBDE concentrations have increased rapidly in the bodies of wildlife and human over the last few decades. Based on the studies on experimental animals, the toxicological endpoints of exposure to PBDEs are likely to be thyroid homeostasis disruption, neuro-developmental deficits, reproductive ineffectiveness and even cancer. Unfortunately, the available molecular toxicological evidence for these endpoints is still very limited. This review focuses on the recent studies on the molecular mechanisms of PBDE toxicities carried out through the hormone receptor pathways, including thyroid hormone receptor, estrogen receptor, androgen receptor, progesterone receptor and aryl hydrocarbon receptor pathways. The general approach in the mechanistic investigation is to examine the in vitro direct binding of a PBDE with a receptor, the in vitro recruitment of a co-activator or co-repressor by the ligand-bound receptor, and the participation of the ligand in the receptor-mediated transcription pathways in cells. It is hoped that further studies in this area would provide more insights into the potential risks of PBDEs to human health.
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Affiliation(s)
- Xiao-Min Ren
- State Key Laboratory of Environmental Chemistry and Eco-toxicology, Research Centre for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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13
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Hwang JY, Attia RR, Carrillo AK, Connelly MC, Guy RK. Synthesis and evaluation of methylsulfonylnitrobenzamides (MSNBAs) as inhibitors of the thyroid hormone receptor-coactivator interaction. Bioorg Med Chem Lett 2013; 23:1891-5. [PMID: 23414840 PMCID: PMC3594046 DOI: 10.1016/j.bmcl.2012.12.055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/13/2012] [Accepted: 12/17/2012] [Indexed: 12/01/2022]
Abstract
We previously identified the methylsulfonylnitrobenzoates (MSNBs) that block the interaction of the thyroid hormone receptor with its obligate transcriptional coactivators and prevent thyroid hormone signaling. As part of our lead optimization work we demonstrated that sulfonylnitrophenylthiazoles (SNPTs), which replace the ester linkage of MSNBs with a thiazole, also inhibited coactivator binding to TR. Here we report that replacement of the ester with an amide (methylsulfonylnitrobenzamides, MSNBA) also provides active TR antagonists.
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Affiliation(s)
- Jong Yeon Hwang
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Ramy R. Attia
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Angela K. Carrillo
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Michele C. Connelly
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - R. Kiplin Guy
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
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14
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Raparti G, Jain S, Ramteke K, Murthy M, Ghanghas R, Ramanand S, Ramanand J. Selective thyroid hormone receptor modulators. Indian J Endocrinol Metab 2013; 17:211-218. [PMID: 23776891 PMCID: PMC3683193 DOI: 10.4103/2230-8210.109663] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Thyroid hormone (TH) is known to have many beneficial effects on vital organs, but its extrapolation to be used therapeutically has been restricted by the fact that it does have concurrent adverse effects. Recent finding of various thyroid hormone receptors (TR) isoforms and their differential pattern of tissue distribution has regained interest in possible use of TH analogues in therapeutics. These findings were followed by search of compounds with isoform-specific or tissue-specific action on TR. Studying the structure-activity relationship of TR led to the development of compounds like GC1 and KB141, which preferentially act on the β1 isoform of TR. More recently, eprotirome was developed and has been studied in humans. It has shown to be effective in dyslipidemia by the lipid-lowering action of TH in the liver and also in obesity. Another compound, 3,5-diiodothyropropionic acid (DITPA), binds to both α- and β-type TRs with relatively low affinity and has been shown to be effective in heart failure (HF). In postinfarction models of HF and in a pilot clinical study, DITPA increased cardiac performance without affecting the heart rate. TR antagonists like NH3 can be used in thyrotoxicosis and cardiac arrhythmias. However, further larger clinical trials on some of these promising compounds and development of newer compounds with increased selectivity is required to achieve higher precision of action and avoid adverse effects seen with TH.
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Affiliation(s)
- Girish Raparti
- Department of Pharmacology, Government Medical College, Miraj, Maharashtra, India
| | - Suyog Jain
- Department of Pharmacology, Government Medical College, Miraj, Maharashtra, India
| | - Karuna Ramteke
- Department of Pharmacology, Government Medical College, Miraj, Maharashtra, India
| | - Mangala Murthy
- Department of Pharmacology, Government Medical College, Miraj, Maharashtra, India
| | - Ravi Ghanghas
- Department of Pharmacology, Government Medical College, Miraj, Maharashtra, India
| | - Sunita Ramanand
- Department of Pharmacology, Government Medical College, Miraj, Maharashtra, India
| | - Jaiprakash Ramanand
- Department of Pharmacology, R.C.S.M. Government Medical College, Kolhapur, Maharashtra, India
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15
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Gierach I, Li J, Wu WY, Grover GJ, Wood DW. Bacterial biosensors for screening isoform-selective ligands for human thyroid receptors α-1 and β-1. FEBS Open Bio 2012; 2:247-53. [PMID: 23667826 PMCID: PMC3642162 DOI: 10.1016/j.fob.2012.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 07/11/2012] [Accepted: 08/08/2012] [Indexed: 12/17/2022] Open
Abstract
Subtype-selective thyromimetics have potential as new pharmaceuticals for the prevention or treatment of heart disease, high LDL cholesterol and obesity, but there are only a few methods that can detect agonistic behavior of TR-active compounds. Among these are the rat pituitary GH3 cell assay and transcriptional activation assays in engineered yeast and mammalian cells. We report the construction and validation of a newly designed TRα-1 bacterial biosensor, which indicates the presence of thyroid active compounds through their impacts on the growth of an engineered Escherichia coli strain in a simple defined medium. This biosensor couples the configuration of a hormone receptor ligand-binding domain to the activity of a thymidylate synthase reporter enzyme through an engineered allosteric fusion protein. The result is a hormone-dependent growth phenotype in the expressing E. coli cells. This sensor can be combined with our previously published TRβ-1 biosensor to detect potentially therapeutic subtype-selective compounds such as GC-1 and KB-141. To demonstrate this capability, we determined the half-maximal effective concentration (EC50) for the compounds T3, Triac, GC-1 and KB-141 using our biosensors, and determined their relative potency in each biosensor strain. Our results are similar to those reported by mammalian cell reporter gene assays, confirming the utility of our assay in identifying TR subtype-selective therapeutics. This biosensor thus provides a high-throughput, receptor-specific, and economical method (less than US$ 0.10 per well at laboratory scale) for identifying important therapeutics against these targets.
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Affiliation(s)
- Izabela Gierach
- Department of Chemical Engineering, Princeton University, Princeton, NJ 08544,USA
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16
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Nandhikonda P, Lynt WZ, McCallum MM, Ara T, Baranowski AM, Yuan NY, Pearson D, Bikle DD, Guy RK, Arnold LA. Discovery of the first irreversible small molecule inhibitors of the interaction between the vitamin D receptor and coactivators. J Med Chem 2012; 55:4640-51. [PMID: 22563729 DOI: 10.1021/jm300460c] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The vitamin D receptor (VDR) is a nuclear hormone receptor that regulates cell proliferation, cell differentiation, and calcium homeostasis. The receptor is activated by vitamin D analogues that induce the disruption of VDR-corepressor binding and promote VDR-coactivator interactions. The interactions between VDR and coregulators are essential for VDR-mediated transcription. Small molecule inhibition of VDR-coregulator binding represents an alternative method to the traditional ligand-based approach in order to modulate the expression of VDR target genes. A high throughput fluorescence polarization screen that quantifies the inhibition of binding between VDR and a fluorescently labeled steroid receptor coactivator 2 peptide was applied to discover the new small molecule VDR-coactivator inhibitors, 3-indolylmethanamines. Structure-activity relationship studies with 3-indolylmethanamine analogues were used to determine their mode of VDR-binding and to produce the first VDR-selective and irreversible VDR-coactivator inhibitors with the ability to regulate the transcription of the human VDR target gene TRPV6.
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Affiliation(s)
- Premchendar Nandhikonda
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53211, United States
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17
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Kollara A, Brown TJ. Expression and function of nuclear receptor co-activator 4: evidence of a potential role independent of co-activator activity. Cell Mol Life Sci 2012; 69:3895-909. [PMID: 22562579 PMCID: PMC3492700 DOI: 10.1007/s00018-012-1000-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 04/13/2012] [Accepted: 04/17/2012] [Indexed: 12/22/2022]
Abstract
Nuclear receptor coactivator 4 (NcoA4), also known as androgen receptor-associated protein 70 (ARA70), was initially discovered as a component of Ret-Fused Gene expressed in a subset of papillary thyroid carcinomas. Subsequent studies have established NcoA4 as a coactivator for a variety of nuclear receptors, including peroxisome proliferator activated receptors α and γ, and receptors for steroid hormones, vitamins D and A, thyroid hormone, and aryl hydrocarbons. While human NcoA4 has both LXXLL and FXXLF motifs that mediate p160 coactivator nuclear receptor interactions, this ubiquitously expressed protein lacks clearly defined functional domains. Several studies indicate that NcoA4 localizes predominantly to the cytoplasm and affects ligand-binding specificity of the androgen receptor, which has important implications for androgen-independent prostate cancer. Two NcoA4 variants, which may exert differential activities, have been identified in humans. Recent studies suggest that NcoA4 may play a role in development, carcinogenesis, inflammation, erythrogenesis, and cell cycle progression that may be independent of its role as a receptor coactivator. This review summarizes what is currently known of the structure, expression, regulation, and potential functions of this unique protein in cancerous and non-cancerous pathologies.
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Affiliation(s)
- Alexandra Kollara
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 25 Orde Street, 6-1001TB, Toronto, ON, M5T 3H7, Canada
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18
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Lévy-Bimbot M, Major G, Courilleau D, Blondeau JP, Lévi Y. Tetrabromobisphenol-A disrupts thyroid hormone receptor alpha function in vitro: use of fluorescence polarization to assay corepressor and coactivator peptide binding. CHEMOSPHERE 2012; 87:782-788. [PMID: 22277881 DOI: 10.1016/j.chemosphere.2011.12.080] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 12/16/2011] [Accepted: 12/30/2011] [Indexed: 05/27/2023]
Abstract
Thyroid hormone receptors (TRs) recruit corepressor or coactivator factors to the promoters of target genes to regulate their transcription. Corepressors such as nuclear hormone receptor corepressor (NCoR) are recruited by unliganded TRs, whereas coactivators such as steroid receptor coactivator-2 (SRC2) are recruited when triiodothyronine (T3) is bound to TRs. These coregulator proteins interact with the ligand binding domain (LBD) of TRs via short, conserved peptide sequences that can be used to probe the conformational changes induced in TR LBD by TR ligands. Recombinant LBD of the human TRα1 isoform (hTRα1 LBD) was produced as a fusion with glutathione S-transferase, and used to develop assays based on fluorescence polarization to quantify the binding of either NCoR- or SRC2-derived fluorescent peptides to the hTRα1 LBD. The optimum concentrations of recombinant hTRα1 LBD, and of peptide probes were adjusted in order to produce the greatest possible T3-dependent signal variations in fluorescence polarization. Under these conditions, T3 induced a dose-dependent decrease in NCoR peptide binding, and a reciprocal dose-dependent increase in SRC2 peptide binding, in both cases at similar 50%-effective doses. The TR agonists triiodothyroacetic acid and thyroxine were also effective in preventing NCoR peptide binding and increasing SRC2 peptide binding, whereas reverse-triiodothyronine was less efficient and the biologically inactive thyronine had no effect on either process. These experiments validate cell-free assays based on the use of binding of corepressor or coactivator peptide probes, as measured by fluorescence polarization, for investigating the conformational changes of TRα1 LBD induced by potentially TR-interfering compounds. Both these methods were used to elucidate the mechanism of the disrupting effects of tetrabromobisphenol-A (TBBPA) on the hTRα1 LBD conformation related to the transcriptional activity of the receptor. TBBPA is a flame retardant that is released into the environment, and is a suspected disrupter of thyroid homeostasis. The present results indicate that TBBPA did indeed interfere with the ability of the hTRα1 LBD to bind both NCoR and SRC2. TBBPA behaved similarly to T3 in promoting the release of NCoR from LBD, whereas it failed to promote LBD interactions with SRC2. However, it did reduce the T3-induced interactions between LBD and the coactivator peptide. This study therefore suggests that TBBPA in the micromolar range can affect the regulation of transcription by both the apo- and the holo-TRα1, with potential disruption of the expression of genes that are either up- or down-regulated by T3.
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19
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Hwang JY, Attia RR, Zhu F, Yang L, Lemoff A, Jeffries C, Connelly MC, Guy RK. Synthesis and evaluation of sulfonylnitrophenylthiazoles (SNPTs) as thyroid hormone receptor-coactivator interaction inhibitors. J Med Chem 2012; 55:2301-10. [PMID: 22324546 DOI: 10.1021/jm201546m] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We previously identified a series of methylsulfonylnitrobenzoates (MSNBs) that block the interaction of the thyroid hormone receptor with its coactivators. MSNBs inhibit coactivator binding through irreversible modification of cysteine 298 of the thyroid hormone receptor (TR). Although MSNBs have better pharmacological features than our first generation inhibitors (β-aminoketones), they contain a potentially unstable ester linkage. Here we report the bioisosteric replacement of the ester linkage with a thiazole moiety, yielding sulfonylnitrophenylthiazoles (SNPTs). An array of SNPTs representing optimal side chains from the MSNB series was constructed using parallel chemistry and evaluated to test their antagonism of the TR-coactivator interaction. Selected active compounds were evaluated in secondary confirmatory assays including regulation of thyroid response element driven transcription in reporter constructs and native genes. In addition the selected SNPTs were shown to be selective for TR relative to other nuclear hormone receptors (NRs).
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Affiliation(s)
- Jong Yeon Hwang
- Medicinal Chemistry Group, Institut Pasteur Korea, 696 Sampyeong-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-400, Korea
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20
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Dong ZN, Wu YS, Wang Z, He A, Li M, Chen M, Du H, Ma Q, Liu T. Effect of temperature on the photoproperties of luminescent terbium sensors for homogeneous bioassays. LUMINESCENCE 2012; 28:156-61. [PMID: 22345047 DOI: 10.1002/bio.2355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2011] [Revised: 11/09/2011] [Accepted: 01/21/2012] [Indexed: 11/09/2022]
Abstract
We developed a luminescent terbium sensor (LTS) based on energy resonance transfer for homogeneous bioassays. The effect of temperature on photoluminescence and time-resolved fluorescence of the LTS was investigated. When the temperature was increased from 277 K to 369 K, the photoluminescence quantum yield decreased by up to 25 %, time-resolved fluorescence decreased by up to 54 %, and the lifetime shortened dramatically. Studies showed that both photoluminescence and time-resolved fluorescence quantum yields were largely recovered after samples were heated from 298 to 310, 333 or 369 K and subsequently cooled to 298 K. These results indicate that the homogeneous bioassay with LTS is sensitive to temperature and should be conducted at a constant temperature to ensure the temperature effect does not influence data and to increase the accuracy of the results. The results of this study are important for LTS applications in homogeneous bioassays.
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Affiliation(s)
- Zhi-Ning Dong
- Institute of Antibody Engineering, School of Biotechnology, Southern Medical University, Guangzhou, Guangdong, China
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21
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Yuan C, Lin JZH, Sieglaff DH, Ayers SD, Denoto-Reynolds F, Baxter JD, Webb P. Identical gene regulation patterns of T3 and selective thyroid hormone receptor modulator GC-1. Endocrinology 2012; 153:501-11. [PMID: 22067320 PMCID: PMC3249679 DOI: 10.1210/en.2011-1325] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Synthetic selective thyroid hormone (TH) receptor (TR) modulators (STRM) exhibit beneficial effects on dyslipidemias in animals and humans and reduce obesity, fatty liver, and insulin resistance in preclinical animal models. STRM differ from native TH in preferential binding to the TRβ subtype vs. TRα, increased uptake into liver, and reduced uptake into other tissues. However, selective modulators of other nuclear receptors exhibit important gene-selective actions, which are attributed to differential effects on receptor conformation and dynamics and can have profound influences in animals and humans. Although there are suggestions that STRM may exhibit such gene-specific actions, the extent to which they are actually observed in vivo has not been explored. Here, we show that saturating concentrations of the main active form of TH, T(3), and the prototype STRM GC-1 induce identical gene sets in livers of euthyroid and hypothyroid mice and a human cultured hepatoma cell line that only expresses TRβ, HepG2. We find one case in which GC-1 exhibits a modest gene-specific reduction in potency vs. T(3), at angiopoietin-like factor 4 in HepG2. Investigation of the latter effect confirms that GC-1 acts through TRβ to directly induce this gene but this gene-selective activity is not related to unusual T(3)-response element sequence, unlike previously documented promoter-selective STRM actions. Our data suggest that T(3) and GC-1 exhibit almost identical gene regulation properties and that gene-selective actions of GC-1 and similar STRM will be subtle and rare.
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Affiliation(s)
- Chaoshen Yuan
- Methodist Hospital Research Institute, F8-045, 6565 Fannin Street, Houston, Texas 77030, USA
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22
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Hwang JY, Huang W, Arnold LA, Huang R, Attia RR, Connelly M, Wichterman J, Zhu F, Augustinaite I, Austin CP, Inglese J, Johnson RL, Guy RK. Methylsulfonylnitrobenzoates, a new class of irreversible inhibitors of the interaction of the thyroid hormone receptor and its obligate coactivators that functionally antagonizes thyroid hormone. J Biol Chem 2011; 286:11895-908. [PMID: 21321127 DOI: 10.1074/jbc.m110.200436] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Thyroid hormone receptors (TRs) are members of the nuclear hormone receptor (NR) superfamily and regulate development, growth, and metabolism. Upon binding thyroid hormone, TR undergoes a conformational change that allows the release of corepressors and the recruitment of coactivators, which in turn regulate target gene transcription. Although a number of TR antagonists have been developed, most are analogs of the endogenous hormone that inhibit ligand binding. In a screen for inhibitors that block the association of TRβ with steroid receptor coactivator 2 (SRC2), we identified a novel methylsulfonylnitrobenzoate (MSNB)-containing series that blocks this interaction at micromolar concentrations. Here we have studied a series of MSNB analogs and characterized their structure activity relationships. MSNB members do not displace thyroid hormone T3 but instead act by direct displacement of SRC2. MSNB series members are selective for the TR over the androgen, vitamin D, and PPARγ NR members, and they antagonize thyroid hormone-activated transcription action in cells. The methylsulfonylnitro group is essential for TRβ antagonism. Side-chain alkylamine substituents showed better inhibitory activity than arylamine substituents. Mass spectrum analysis suggested that MSNB inhibitors bind irreversibly to Cys-298 within the AF-2 cleft of TRβ to disrupt SRC2 association.
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Affiliation(s)
- Jong Yeon Hwang
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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23
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Pfaff SJ, Fletterick RJ. Hormone binding and co-regulator binding to the glucocorticoid receptor are allosterically coupled. J Biol Chem 2010; 285:15256-15267. [PMID: 20335180 PMCID: PMC2865338 DOI: 10.1074/jbc.m110.108118] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 03/09/2010] [Indexed: 12/19/2022] Open
Abstract
The glucocorticoid receptor initiates the cellular response to glucocorticoid steroid hormones in vertebrates. Co-regulator proteins dock to the receptor in response to hormone binding and potentiate the transcriptional activity of the receptor by modifying DNA and recruiting essential transcription factors like RNA polymerase II. Hormones and co-regulators bind at distinct sites in the ligand binding domain yet function cooperatively to mediate transcriptional control. This study reveals and quantifies energetic coupling between two binding sites using purified components. Using a library of peptides taken from co-regulator proteins, we determine the pattern of co-regulator binding to the glucocorticoid receptor ligand binding domain. We show that peptides from co-regulators differ in their effects on hormone binding and kinetics. Peptides from DAX1 and SRC1 bind with similar affinity, but DAX1 binding is coupled to hormone binding, and SRC1 is not. Mechanistic details of co-regulator binding and coupling to the hormone binding pocket are uncovered by analysis of properties endowed by mutation of a key residue in the allosteric network connecting the sites.
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Affiliation(s)
- Samuel J Pfaff
- Graduate Group in Biophysics, University of California, San Francisco, California 94143
| | - Robert J Fletterick
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143.
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24
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Nedumaran B, Kim GS, Hong S, Yoon YS, Kim YH, Lee CH, Lee YC, Koo SH, Choi HS. Orphan nuclear receptor DAX-1 acts as a novel corepressor of liver X receptor alpha and inhibits hepatic lipogenesis. J Biol Chem 2010; 285:9221-32. [PMID: 20080977 DOI: 10.1074/jbc.m109.073650] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
DAX-1 (dosage-sensitive sex reversal adrenal hypoplasia congenital critical region on X chromosome, gene 1) is a member of the nuclear receptor superfamily that can repress diverse nuclear receptors and has a key role in adreno-gonadal development. Our previous report has demonstrated that DAX-1 can inhibit hepatocyte nuclear factor 4alpha transactivity and negatively regulate gluconeogenic gene expression (Nedumaran, B., Hong, S., Xie, Y. B., Kim, Y. H., Seo, W. Y., Lee, M. W., Lee, C. H., Koo, S. H., and Choi, H. S. (2009) J. Biol. Chem. 284, 27511-27523). Here, we further expand the role of DAX-1 in hepatic energy metabolism. Transfection assays have demonstrated that DAX-1 can inhibit the transcriptional activity of nuclear receptor liver X receptor alpha (LXRalpha). Physical interaction between DAX-1 and LXRalpha was confirmed Immunofluorescent staining in mouse liver shows that LXRalpha and DAX-1 are colocalized in the nucleus. Domain mapping analysis shows that the entire region of DAX-1 is involved in the interaction with the ligand binding domain region of LXRalpha. Competition analyses demonstrate that DAX-1 competes with the coactivator SRC-1 for repressing LXRalpha transactivity. Chromatin immunoprecipitation assay showed that endogenous DAX-1 recruitment on the SREBP-1c gene promoter was decreased in the presence of LXRalpha agonist. Overexpression of DAX-1 inhibits T7-induced LXRalpha target gene expression, whereas knockdown of endogenous DAX-1 significantly increases T7-induced LXRalpha target gene expression in HepG2 cells. Finally, overexpression of DAX-1 in mouse liver decreases T7-induced LXRalpha target gene expression, liver triglyceride level, and lipid accumulation. Overall, this study suggests that DAX-1, a novel corepressor of LXRalpha, functions as a negative regulator of lipogenic enzyme gene expression in liver.
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Affiliation(s)
- Balachandar Nedumaran
- Hormone Research Center, School of Biological Science and Technology, Chonnam National University, Gwangju 500-757, Korea
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25
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Moore TW, Mayne CG, Katzenellenbogen JA. Minireview: Not picking pockets: nuclear receptor alternate-site modulators (NRAMs). Mol Endocrinol 2009; 24:683-95. [PMID: 19933380 DOI: 10.1210/me.2009-0362] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Because of their central importance in gene regulation and mediating the actions of many hormones, the nuclear receptors (NRs) have long been recognized as very important biological and pharmaceutical targets. Of all the surfaces available on a given NR, the singular site for regulation of receptor activity has almost invariably been the ligand-binding pocket of the receptor, the site where agonists, antagonists, and selective NR modulators interact. With our increasing understanding of the multiple molecular components involved in NR action, researchers have recently begun to look to additional interaction sites on NRs for regulating their activities by novel mechanisms. The alternate NR-associated interaction sites that have been targeted include the coactivator-binding groove and allosteric sites in the ligand-binding domain, the zinc fingers of the DNA-binding domain, and the NR response element in DNA. The studies thus far have been performed with the estrogen receptors, the androgen receptor (AR), the thyroid hormone receptors, and the pregnane X receptor. Phenotypic and conformation-based screens have also identified small molecule modulators that are believed to function through the NRs but have, as yet, unknown sites and mechanisms of action. The rewards from investigation of these NR alternate-site modulators should be the discovery of new therapeutic approaches and novel agents for regulating the activities of these important NR proteins.
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Affiliation(s)
- Terry W Moore
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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26
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Putcha BDK, Fernandez EJ. Direct interdomain interactions can mediate allosterism in the thyroid receptor. J Biol Chem 2009; 284:22517-24. [PMID: 19561066 PMCID: PMC2755658 DOI: 10.1074/jbc.m109.026682] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 06/25/2009] [Indexed: 11/06/2022] Open
Abstract
The thyroid (TR) and retinoid X receptors (RXR) belong to the nuclear receptor (NR) superfamily of ligand-mediated transcription factors. At the molecular level, TR activity is specifically modulated by interactions with the ligand 3,3',5 triiodo-l-thyronine (T3), RXR, DNA, and co-activators such as SRC1, occurring in concert or sequentially. Although binding sites for DNA and coregulators such as SRC1 are distinct and at distal regions of these receptors, cell-based and EMSA studies have suggested that these molecules can regulate binding of each other to the receptor. We present evidence of direct, DNA-dependent, communication between the DNA and ligand binding domains (DBD and LBD) that can allosterically regulate interactions with SRC1 and DNA, respectively, using isothermal titration calorimetry (ITC) and cell-based assays. Additionally, we note that interdomain communication is affected by RXR in RXR:TR. We also noticed a DNA-dependent cross-talk between RXR and TR within RXR:TR. Finally, we suggest that differences in transactivation on different TRE may be the consequence of different affinities between TRE and RXR:TR.
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Affiliation(s)
- Balananda-Dhurjati K. Putcha
- From the Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996
| | - Elias J. Fernandez
- From the Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996
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27
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Thyroid hormone mimetics: potential applications in atherosclerosis, obesity and type 2 diabetes. Nat Rev Drug Discov 2009; 8:308-20. [PMID: 19337272 DOI: 10.1038/nrd2830] [Citation(s) in RCA: 174] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Thyroid hormones influence heart rate, serum lipids, metabolic rate, body weight and multiple aspects of lipid, carbohydrate, protein and mineral metabolism. Although increased thyroid hormone levels can improve serum lipid profiles and reduce fat, these positive effects are counterbalanced by harmful effects on the heart, muscle and bone. Thus, attempts to use thyroid hormones for cholesterol-lowering and weight loss purposes have so far been limited. However, over the past decade, thyroid hormone analogues that are capable of uncoupling beneficial effects from deleterious effects have been developed. Such drugs could serve as powerful new tools to address two of the largest medical problems in developed countries--atherosclerosis and obesity.
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28
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Teichert A, Arnold LA, Otieno S, Oda Y, Augustinaite I, Geistlinger TR, Kriwacki RW, Guy RK, Bikle DD. Quantification of the vitamin D receptor-coregulator interaction. Biochemistry 2009; 48:1454-61. [PMID: 19183053 DOI: 10.1021/bi801874n] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The vitamin D receptor (VDR) regulates a diverse set of genes that control processes including bone mineral homeostasis, immune function, and hair follicle cycling. Upon binding to its natural ligand, 1alpha,25(OH)(2)D(3), the VDR undergoes a conformational change that allows the release of corepressor proteins and the binding of coactivator proteins necessary for gene transcription. We report the first comprehensive evaluation of the interaction of the VDR with a library of coregulator binding motifs in the presence of two ligands, the natural ligand 1alpha,25(OH)(2)D(3) and a synthetic, nonsecosteroidal agonist LG190178. We show that the VDR has relatively high affinity for the second and third LxxLL motifs of SRC1, SRC2, and SRC3 and second LxxLL motif of DRIP205. This pattern is distinct in comparison to other nuclear receptors. The pattern of VDR-coregulator binding affinities was very similar for the two agonists investigated, suggesting that the biologic functions of LG190178 and 1alpha,25(OH)(2)D(3) are similar. Hairless binds the VDR in the presence of ligand through a LxxLL motif (Hr-1), repressing transcription in the presence and absence of ligand. The VDR binding patterns identified in this study may be used to predict functional differences among different tissues expressing different sets of coregulators, thus facilitating the goal of developing tissue- and gene-specific vitamin D response modulators.
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Affiliation(s)
- Arnaud Teichert
- Endocrine Unit, University of California, San Francisco, San Francisco, California 94121, USA
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29
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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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30
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Valadares NF, Polikarpov I, Garratt RC. Ligand induced interaction of thyroid hormone receptor beta with its coregulators. J Steroid Biochem Mol Biol 2008; 112:205-12. [PMID: 19000767 DOI: 10.1016/j.jsbmb.2008.10.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 10/08/2008] [Accepted: 10/09/2008] [Indexed: 12/12/2022]
Abstract
Thyroid hormones exert most of their physiological effects through two thyroid hormone receptor (TR) subtypes, TRalpha and TRbeta, which associate with many transcriptional coregulators to mediate activation or repression of target genes. The search for selective TRbeta ligands has been stimulated by the finding that several pharmacological actions mediated by TRbeta might be beneficial in medical conditions such as obesity, hypercholesterolemia and diabetes. Here, we present a new methodology which employs surface plasmon resonance to investigate the interactions between TRbeta ligand binding domain (LBD) complexes and peptides derived from the nuclear receptor interaction motifs of two of its coregulators, SRC2 and DAX1. The effect of several TRbeta ligands, including the TRbeta selective agonist GC-1 and the TRbeta selective antagonist NH-3, were investigated. We also determined the kinetic rate constants for the interaction of TRbeta-T3 with both coregulators, and accessed the thermodynamic parameters for the interaction with DAX1. Our findings suggest that flexibility plays an important role in the interaction between the receptor and its coregulators, and point out important aspects of experimental design that should be addressed when using TRbeta LBD and its agonists. Furthermore, the methodology described here may be useful for the identification of new TRbeta ligands.
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Affiliation(s)
- Napoleão F Valadares
- Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São-carlense 400, 13560-970 São Carlos, SP, Brazil.
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31
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Sablin EP, Woods A, Krylova IN, Hwang P, Ingraham HA, Fletterick RJ. The structure of corepressor Dax-1 bound to its target nuclear receptor LRH-1. Proc Natl Acad Sci U S A 2008; 105:18390-5. [PMID: 19015525 PMCID: PMC2587556 DOI: 10.1073/pnas.0808936105] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Indexed: 11/18/2022] Open
Abstract
The Dax-1 protein is an enigmatic nuclear receptor that lacks an expected DNA binding domain, yet functions as a potent corepressor of nuclear receptors. Here we report the structure of Dax-1 bound to one of its targets, liver receptor homolog 1 (LRH-1). Unexpectedly, Dax-1 binds to LRH-1 using a new module, a repressor helix built from a family conserved sequence motif, PCFXXLP. Mutations in this repressor helix that are linked with human endocrine disorders dissociate the complex and attenuate Dax-1 function. The structure of the Dax-1:LRH-1 complex provides the molecular mechanism for the function of Dax-1 as a potent transcriptional repressor.
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Affiliation(s)
| | - April Woods
- Departments of Biochemistry and Biophysics and
| | - Irina N. Krylova
- Molecular and Cellular Pharmacology, University of California, San Francisco, CA 94143
| | - Peter Hwang
- Departments of Biochemistry and Biophysics and
| | - Holly A. Ingraham
- Molecular and Cellular Pharmacology, University of California, San Francisco, CA 94143
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32
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Xia Z, Webster A, Du F, Piatkov K, Ghislain M, Varshavsky A. Substrate-binding sites of UBR1, the ubiquitin ligase of the N-end rule pathway. J Biol Chem 2008; 283:24011-28. [PMID: 18566452 DOI: 10.1074/jbc.m802583200] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Substrates of a ubiquitin-dependent proteolytic system called the N-end rule pathway include proteins with destabilizing N-terminal residues. N-recognins, the pathway's ubiquitin ligases, contain three substrate-binding sites. The type-1 site is specific for basic N-terminal residues (Arg, Lys, and His). The type-2 site is specific for bulky hydrophobic N-terminal residues (Trp, Phe, Tyr, Leu, and Ile). We show here that the type-1/2 sites of UBR1, the sole N-recognin of the yeast Saccharomyces cerevisiae, are located in the first approximately 700 residues of the 1,950-residue UBR1. These sites are distinct in that they can be selectively inactivated by mutations, identified through a genetic screen. Mutations inactivating the type-1 site are in the previously delineated approximately 70-residue UBR motif characteristic of N-recognins. Fluorescence polarization and surface plasmon resonance were used to determine that UBR1 binds, with a K(d) of approximately 1 microm, to either type-1 or type-2 destabilizing N-terminal residues of reporter peptides but does not bind to a stabilizing N-terminal residue such as Gly. A third substrate-binding site of UBR1 targets an internal degron of CUP9, a transcriptional repressor of peptide import. We show that the previously demonstrated in vivo dependence of CUP9 ubiquitylation on the binding of cognate dipeptides to the type-1/2 sites of UBR1 can be reconstituted in a completely defined in vitro system. We also found that purified UBR1 and CUP9 interact nonspecifically and that specific binding (which involves, in particular, the binding by cognate dipeptides to the UBR1 type-1/2 sites) can be restored either by a chaperone such as EF1A or through macromolecular crowding.
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Affiliation(s)
- Zanxian Xia
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
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33
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Brenta G, Danzi S, Klein I. Potential therapeutic applications of thyroid hormone analogs. ACTA ACUST UNITED AC 2008; 3:632-40. [PMID: 17710084 DOI: 10.1038/ncpendmet0590] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Accepted: 06/20/2007] [Indexed: 12/20/2022]
Abstract
Thyroid hormone (T3 and T4) has many beneficial effects including enhancing cardiac function, promoting weight loss and reducing serum cholesterol. Excess thyroid hormone is, however, associated with unwanted effects on the heart, bone and skeletal muscle. We therefore need analogs that harness the beneficial effects of thyroid hormone without the untoward effects. Such work is largely based on understanding the cellular mechanisms of thyroid hormone action, specifically the crystal structure of the nuclear receptor proteins. In clinical studies, use of naturally occurring thyroid hormone analogs can suppress TSH levels in patients with thyroid cancer without producing tachycardia. Many thyromimetic compounds have been tested in animal models and shown to increase total body oxygen consumption, and to lower weight and serum cholesterol and triglyceride levels while having minor effects on heart rate. Alternatively, analogs that specifically enhance both systolic and diastolic function are potentially useful in the treatment of chronic congestive heart failure. In addition to analogs that are thyroid hormone receptor agonists, several compounds that are thyroid hormone receptor antagonists have been identified and tested. This Review discusses the potential application of thyroid hormone analogs (both agonists and antagonists) in a variety of human disease states.
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Affiliation(s)
- Gabriela Brenta
- School of Medicine, Favaloro University of Buenos Aires, Argentina
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34
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White R, Morganstein D, Christian M, Seth A, Herzog B, Parker MG. Role of RIP140 in metabolic tissues: Connections to disease. FEBS Lett 2007; 582:39-45. [DOI: 10.1016/j.febslet.2007.11.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Accepted: 11/06/2007] [Indexed: 01/06/2023]
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35
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Arnold LA, Kosinski A, Estébanez-Perpiñá E, Fletterick RJ, Guy RK. Inhibitors of the interaction of a thyroid hormone receptor and coactivators: preliminary structure-activity relationships. J Med Chem 2007; 50:5269-80. [PMID: 17918822 DOI: 10.1021/jm070556y] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The modulation of gene regulation by blocking the interaction between the thyroid receptor (TR) and obligate coregulators has been reported recently with the discovery of the lead compound 3-(dimethylamino)-1-(4-hexylphenyl)propan-1-one). Herein we report studies aimed at optimization of this initial hit to determine the basic parameters of the structure-activity relationships and clarify the mechanism of action. These studies provided new insights, showing that activity and TRbeta isoform selectivity is highly correlated with the structural composition of these covalent inhibitors.
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Affiliation(s)
- Leggy A Arnold
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 332 N. Lauderdale, Memphis, Tennessee 38105, USA
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36
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Tai PJ, Huang YH, Shih CH, Chen RN, Chen CD, Chen WJ, Wang CS, Lin KH. Direct regulation of androgen receptor-associated protein 70 by thyroid hormone and its receptors. Endocrinology 2007; 148:3485-95. [PMID: 17412801 DOI: 10.1210/en.2006-1239] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thyroid hormone (T3) regulates multiple physiological processes during development, growth, differentiation, and metabolism. Most T3 actions are mediated via thyroid hormone receptors (TRs) that are members of the nuclear hormone receptor superfamily of ligand-dependent transcription factors. The effects of T3 treatment on target gene regulation was previously examined in TRalpha1-overexpressing hepatoma cell lines (HepG2-TRalpha1). Androgen receptor (AR)-associated protein 70 (ARA70) was one gene found to be up-regulated by T3. The ARA70 is a ligand-dependent coactivator for the AR and was significantly increased by 4- to 5-fold after T3 treatment by Northern blot analyses in the HepG2-TRalpha1 stable cell line. T3 induced a 1- to 2-fold increase in the HepG2-TRbeta1 stable cell line. Both stable cell lines attained the highest fold expression after 24 h treatment with 10 nM T3. The ARA70 protein was increased up to 1.9-fold after T3 treatment in HepG2-TRalpha1 cells. Similar findings were obtained in thyroidectomized rats after T3 application. Cycloheximide treatment did not suppress induction of ARA70 transcription by T3, suggesting that this regulation is direct. A series of deletion mutants of ARA70 promoter fragments in pGL2 plasmid were generated to localize the thyroid hormone response element (TRE). The DNA fragments (-234/-190 or +56/+119) gave 1.55- or 2-fold enhanced promoter activity by T3. Thus, two TRE sites exist in the upstream-regulatory region of ARA70. The TR-TRE interaction was further confirmed with EMSAs. Additionally, ARA70 could interfere with TR/TRE complex formation. Therefore, the data indicated that ARA70 suppresses T3 signaling in a TRE-dependent manner. These experimental results suggest that T3 directly up-regulates ARA70 gene expression. Subsequently, ARA70 negatively regulates T3 signaling.
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Affiliation(s)
- Pei-Ju Tai
- Department of Biochemistry, Chang-Gung University, and First Cardiovascular Division, Chang Gung Memorial Hospital, 259 Wen-hwa 1 Road, Taoyuan, Taiwan 333, Republic of China
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37
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Grover GJ, Dunn C, Nguyen NH, Boulet J, Dong G, Domogauer J, Barbounis P, Scanlan TS. Pharmacological Profile of the Thyroid Hormone Receptor Antagonist NH3 in Rats. J Pharmacol Exp Ther 2007; 322:385-90. [PMID: 17440037 DOI: 10.1124/jpet.106.116152] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
NH3 is a thyroid hormone receptor (TR) antagonist that inhibits binding of thyroid hormones to their receptor and that inhibits cofactor recruitment. It was active in a tadpole tail resorption assay, with partial agonist activity at high concentrations. We determined the effect of NH3 on the cholesterol-lowering, thyroid stimulating hormone (TSH)-lowering, and tachycardic action of thyroid hormone (T(3)) in rats. Cholesterol-fed, euthyroid rats were treated for 7 days with NH3, and a dose response (46.2-27,700 nmol/kg/day) was determined. We also determined the effect of two doses of T(3) on the NH3 dose-response curve. NH3 decreased heart rate modestly starting at 46.2 nmol/kg/day, but the effect was lost at >2920 nmol/kg/day. At 27,700 nmol/kg/day, tachycardia was seen, suggesting partial agonist activity. NH3 increased plasma cholesterol to a maximum of 27% at 462 nmol/kg/day. At higher doses, cholesterol was reduced, suggesting partial agonist activity. Plasma TSH was increased from 46.2 to 462 nmol/kg/day NH3, but at higher doses, this effect was lost, and partial agonist effects were apparent. T(3) at 15.4 and 46.2 nmol/kg/day increased heart rate, reduced cholesterol, and reduced plasma TSH. NH3 inhibited the cholesterol-lowering, TSH-lowering and tachycardic effects of 15.4 nmol/kg/day T(3), but much of the effect was lost at >924 nmol/kg/day doses. NH3 had no effect on the cholesterol-lowering action of 46.2 nmol/kg/day T(3), but it inhibited the tachycardic and TSH suppressant effects up to the 924 nmol/kg/day dose. Single doses of 462 and 27,700 nmol/kg caused no TR inhibitory effects. In conclusion, NH3 has TR antagonist properties on T(3)-responsive parameters, but it has partial agonist properties at higher doses.
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Affiliation(s)
- Gary J Grover
- Eurofins Scientific--Product Safety Laboratories, 2394 Hwy. 130, Dayton, NJ 08810, USA.
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Parker MG, Christian M, White R. The nuclear receptor co-repressor RIP140 controls the expression of metabolic gene networks. Biochem Soc Trans 2007; 34:1103-6. [PMID: 17073760 DOI: 10.1042/bst0341103] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
NRs (nuclear receptors) regulate the expression of specific gene networks in target cells by recruiting cofactor complexes involved in chromatin remodelling and in the assembly of transcription complexes. The importance of activating gene expression, in metabolic tissues, is well established, but the contribution of transcriptional inhibition is less well defined. In this review, we highlight a crucial role for RIP140 (receptor-interacting protein 140), a transcriptional co-repressor for NR, in the regulation of metabolic gene expression. Many genes involved in lipid and carbohydrate metabolism are repressed by RIP140 in adipose and muscle. The repressive function of RIP140 results from its ability to bridge NRs to repressive enzyme complexes that modify DNA and histones. In the absence of RIP140, expression from many metabolic genes is increased so that mice exhibit a lean phenotype and resistance to high-fat-diet-induced obesity and display increased glucose tolerance and insulin sensitivity. We propose that a functional interplay between transcriptional activators and the co-repressor RIP140 is an essential process in metabolic regulation.
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Affiliation(s)
- M G Parker
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK.
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39
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Augereau P, Badia E, Carascossa S, Castet A, Fritsch S, Harmand PO, Jalaguier S, Cavaillès V. The nuclear receptor transcriptional coregulator RIP140. NUCLEAR RECEPTOR SIGNALING 2006; 4:e024. [PMID: 17088940 PMCID: PMC1630689 DOI: 10.1621/nrs.04024] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 10/17/2006] [Indexed: 12/21/2022]
Abstract
The nuclear receptor superfamily comprises ligand-regulated transcription factors that control various developmental and physiological pathways. These receptors share a common modular structure and regulate gene expression through the recruitment of a large set of coregulatory proteins. These transcription cofactors regulate, either positively or negatively, chromatin structure and transcription initiation. One of the first proteins to be identified as a hormone-recruited cofactor was RIP140. Despite its recruitment by agonist-liganded receptors, RIP140 exhibits a strong transcriptional repressive activity which involves several inhibitory domains and different effectors. Interestingly, the RIP140 gene, located on chromosome 21 in humans, is finely regulated at the transcriptional level by various nuclear receptors. In addition, the protein undergoes several post-translational modifications which control its repressive activity. Finally, experiments performed in mice devoid of the RIP140 gene indicate that this transcriptional cofactor is essential for female fertility and energy homeostasis. RIP140 therefore appears to be an important modulator of nuclear receptor activity which could play major roles in physiological processes and hormone-dependent diseases.
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Li JM, Wang XF, Xi ZQ, Gong Y, Liu FY, Sun JJ, Wu Y, Luan GM, Wang YP, Li YL, Zhang JG, Lu Y, Li HW. Decreased expression of thyroid receptor-associated protein 220 in temporal lobe tissue of patients with refractory epilepsy. Biochem Biophys Res Commun 2006; 348:1389-97. [PMID: 16934225 DOI: 10.1016/j.bbrc.2006.08.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2006] [Accepted: 08/02/2006] [Indexed: 11/22/2022]
Abstract
PURPOSE TRAP220 (thyroid hormone receptor-associated protein) functions as a coactivator for nuclear receptors and stimulates transcription by recruiting the TRAP mediator complex to hormone responsive promoter regions. Thus, TRAP220 enhances the function of thyroid/steroid hormone receptors such as thyroid hormone and oestrogen receptors. This study investigated the expression of TRAP220 mRNA and protein level in epileptic brains comparing with human control. METHODS We examined the expression of TRAP220 mRNA and protein levels in temporal lobes from patients with chronic pharmacoresistant epilepsy who have undergone surgery. RESULTS Expression of TRAP220 mRNA and protein was shown to be decreased significantly in the temporal cortex of the patients with epilepsy. CONCLUSIONS Our work showed that a decrease in TRAP220 mRNA and protein levels may be involved in the pathophysiology of epilepsy and may be associated with impairment of the brain caused by frequent seizures.
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Affiliation(s)
- Jin-Mei Li
- Neurology Department, The First Affiliated Hospital, Chongqing University of Medical Sciences, Chongqing 4000162, China
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Christian M, White R, Parker MG. Metabolic regulation by the nuclear receptor corepressor RIP140. Trends Endocrinol Metab 2006; 17:243-50. [PMID: 16815031 DOI: 10.1016/j.tem.2006.06.008] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Revised: 05/25/2006] [Accepted: 06/20/2006] [Indexed: 01/07/2023]
Abstract
Whereas the importance of activating gene expression in metabolic pathways to control energy homeostasis is well established, the contribution of transcriptional inhibition is less well defined. In this review we highlight a crucial role of RIP140, a transcriptional corepressor for nuclear receptors, in the regulation of energy expenditure. Mice devoid of the RIP140 gene are lean, exhibit resistance to high-fat-diet-induced obesity, and have increased glucose tolerance and insulin sensitivity. Consistent with these observations, RIP140 suppresses the expression of gene clusters that are involved in lipid and carbohydrate metabolism, including fatty acid oxidation, oxidative phosphorylation and mitochondrial uncoupling. Therefore, the functional interplay between transcriptional activators and the corepressor RIP140 is an essential process in metabolic regulation.
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Affiliation(s)
- Mark Christian
- Institute of Reproductive and Developmental Biology, Imperial College London, Faculty of Medicine, Du Cane Road, London W12 0NN, UK
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42
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Arnold LA, Estébanez-Perpiñá E, Togashi M, Shelat A, Ocasio CA, McReynolds AC, Nguyen P, Baxter JD, Fletterick RJ, Webb P, Guy RK. A high-throughput screening method to identify small molecule inhibitors of thyroid hormone receptor coactivator binding. Sci Signal 2006; 2006:pl3. [PMID: 16804159 DOI: 10.1126/stke.3412006pl3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
To provide alternative methods for regulation of gene transcription initiated by the binding of thyroid hormone (T3) to the thyroid receptor (TR), we have developed a high-throughput method for discovering inhibitors of the interaction of TR with its transcriptional coactivators. The screening method is based on fluorescence polarization (FP), one of the most sensitive and robust high-throughput methods for the study of protein-protein interactions. A fluorescently labeled coactivator is excited by polarized light. The emitted polarized light is a function of the molecular properties of the labeled coactivator, especially Brownian molecular rotation, which is very sensitive to changes in the molecular mass of the labeled complex. Dissociation of hormone receptor from fluorescently labeled coactivator peptide in the presence of small molecules can be detected by this competition method, and the assay can be performed in a high-throughput screening format. Hit compounds identified by this method are evaluated by several secondary assay methods, including a dose-response analysis, a semiquantitative glutathione-S-transferase assay, and a hormone displacement assay. Subsequent in vitro transcription assays can detect inhibition of thyroid signaling at low micromolar concentrations of small molecules in the presence of T3.
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Affiliation(s)
- Leggy A Arnold
- St. Jude Children's Research Hospital, Department of Chemical Biology and Therapeutics, 333 North Lauderdale Street, Memphis, TN 38105-2794, USA.
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Arnold LA, Estébanez-Perpiñá E, Togashi M, Jouravel N, Shelat A, McReynolds AC, Mar E, Nguyen P, Baxter JD, Fletterick RJ, Webb P, Guy RK. Discovery of Small Molecule Inhibitors of the Interaction of the Thyroid Hormone Receptor with Transcriptional Coregulators. J Biol Chem 2005; 280:43048-55. [PMID: 16263725 DOI: 10.1074/jbc.m506693200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Thyroid hormone (3,5,3'-triiodo-L-thyronine, T3) is an endocrine hormone that exerts homeostatic regulation of basal metabolic rate, heart rate and contractility, fat deposition, and other phenomena (1, 2). T3 binds to the thyroid hormone receptors (TRs) and controls their regulation of transcription of target genes. The binding of TRs to thyroid hormone induces a conformational change in TRs that regulates the composition of the transcriptional regulatory complex. Recruitment of the correct coregulators (CoR) is important for successful gene regulation. In principle, inhibition of the TR-CoR interaction can have a direct influence on gene transcription in the presence of thyroid hormones. Herein we report a high throughput screen for small molecules capable of inhibiting TR coactivator interactions. One class of inhibitors identified in this screen was aromatic beta-aminoketones, which exhibited IC50 values of approximately 2 microm. These compounds can undergo a deamination, generating unsaturated ketones capable of reacting with nucleophilic amino acids. Several experiments confirm the hypothesis that these inhibitors are covalently bound to TR. Optimization of these compounds produced leads that inhibited the TR-CoR interaction in vitro with potency of approximately 0.6 microm and thyroid signaling in cellular systems. These are the first small molecules irreversibly inhibiting the coactivator binding of a nuclear receptor and suppressing its transcriptional activity.
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Affiliation(s)
- Leggy A Arnold
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143, USA
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Mousa SA, O'Connor LJ, Bergh JJ, Davis FB, Scanlan TS, Davis PJ. The proangiogenic action of thyroid hormone analogue GC-1 is initiated at an integrin. J Cardiovasc Pharmacol 2005; 46:356-60. [PMID: 16116342 DOI: 10.1097/01.fjc.0000175438.94906.a0] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Our early reported investigations have demonstrated potent proangiogenic effects of L-thyroxine (T4) and 3,5,3'-triiodo-L-thyronine (T3) in the chick chorioallantoic membrane (CAM) model. Tetraiodothyroacetic acid (tetrac) blocks T4 binding to plasma membranes and its pro-angiogenic effect. T4/T3 stimulates expression of fibroblast growth factor 2 (FGF2) in endothelial cells. Thyroid hormone (T4/T3) is principally responsible for transcriptional activation mediated by nuclear thyroid hormone receptors TRbeta and TRalpha. In contrast, the hormone analogue GC-1 also stimulates transcriptional activation via TRbeta1. In the present study, we have defined the effect of GC-1, compared with T4 and T4-agarose, on angiogenesis in the CAM assay. GC-1 demonstrated a proangiogenic effect similar to that of T4 and T4-agarose. Tetrac inhibited GC-1- and T4-induced angiogenesis, indicating dependence on T4 and GC-1 binding to plasma membranes. The effects of GC-1, T4-agarose, and FGF2 were blocked by PD 98059, a mitogen-activated protein kinase (MAPK) pathway inhibitor. Additionally, the alphavbeta3 integrin antagonist XT199 inhibited angiogenesis induced by T4-agarose, GC-1, or FGF2. Thus, the proangiogenic effects of GC-1 and T4 are initiated at the plasma membrane, require interaction with alphavbeta3 integrin receptor, and are dependent on MAPK activation.
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Affiliation(s)
- Shaker A Mousa
- Pharmaceutical Research Institute at Albany and Albany College of Pharmacy, Albany, New York 12208, USA.
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46
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Abstract
The beta-catenin pathway has been conclusively demonstrated to regulate differentiation and patterning in multiple model systems. In thyroid cancer, alterations are often seen in proteins that regulate beta-catenin, including those of the RAS, PI3K/AKT, and peroxisome proliferation activated receptor-gamma (PPARgamma) pathways, and evidence from the literature suggests that beta-catenin may play a direct role in the dedifferentiation commonly observed in late-stage disease. RET/PTC rearrangements are frequent in thyroid cancer and appear to be exclusive from mutational events in RAS and BRAF. Activation of AKT by phosphatidylinositide-3 kinase (PI3K), a RAS effector, results in GSK3beta phosphorylation and deactivation and subsequent beta-catenin upregulation in thyroid cancer. Activating mutations in beta-catenin, which have been demonstrated in late-stage thyroid tumors, correlate with beta-catenin nuclear localization and poor prognosis. We hypothesize that activation of the RAS, PI3K/AKT, and PPARgamma pathways ultimately impinges upon beta-catenin. We further propose that if mutations in BRAF, RAS, and RET/PTC rearrangements are mutually exclusive in certain thyroid tumors or tumor types, as has already been shown for papillary thyroid cancer, then these interconnected pathways may cooperate in the initiation and promotion of the disease. We believe that clinical benefit for thyroid cancer patients could be derived from disrupting the middle or distal pathway effectors of these pathways, such as AKT or beta-catenin.
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Affiliation(s)
- Phillip H Abbosh
- Indiana University School of Medicine, Medical Sciences, Bloomington, Indiana, USA.
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Abstract
The thyroid hormone receptor (TR) directly regulates the transcription of thyroid hormone-responsive genes in response to changing levels of thyroid hormone. Mechanistically TR utilizes a complex set of binding interactions, with hormone, response elements, and coregulatory proteins, to provide specific local control of patterns of transcriptional response that are partially responsible for inducing the tissue-selective responses to the circulating hormone. One of the apparently dominant phenomena in the regulation of thyroid hormone responses is the protein interactions between TR and its coregulators. This review summarizes the current state of knowledge with respect to the identity of these coregulators, their interaction with TR, and the consequences of those interactions.
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Affiliation(s)
- Jamie M R Moore
- Department of Late Stage Formulation Development, Genentech, South San Francisco, California 94080, USA
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Krylova IN, Sablin EP, Moore J, Xu RX, Waitt GM, MacKay JA, Juzumiene D, Bynum JM, Madauss K, Montana V, Lebedeva L, Suzawa M, Williams JD, Williams SP, Guy RK, Thornton JW, Fletterick RJ, Willson TM, Ingraham HA. Structural analyses reveal phosphatidyl inositols as ligands for the NR5 orphan receptors SF-1 and LRH-1. Cell 2005; 120:343-55. [PMID: 15707893 DOI: 10.1016/j.cell.2005.01.024] [Citation(s) in RCA: 320] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Revised: 01/13/2005] [Accepted: 01/27/2005] [Indexed: 12/19/2022]
Abstract
Vertebrate members of the nuclear receptor NR5A subfamily, which includes steroidogenic factor 1 (SF-1) and liver receptor homolog 1 (LRH-1), regulate crucial aspects of development, endocrine homeostasis, and metabolism. Mouse LRH-1 is believed to be a ligand-independent transcription factor with a large and empty hydrophobic pocket. Here we present structural and biochemical data for three other NR5A members-mouse and human SF-1 and human LRH-1-which reveal that these receptors bind phosphatidyl inositol second messengers and that ligand binding is required for maximal activity. Evolutionary analysis of structure-function relationships across the SF-1/LRH-1 subfamily indicates that ligand binding is the ancestral state of NR5A receptors and was uniquely diminished or altered in the rodent LRH-1 lineage. We propose that phospholipids regulate gene expression by directly binding to NR5A nuclear receptors.
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Affiliation(s)
- Irina N Krylova
- Department of Physiology, University of California, San Francisco, California 94143, USA
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Estébanez-Perpiñá E, Moore JMR, Mar E, Delgado-Rodrigues E, Nguyen P, Baxter JD, Buehrer BM, Webb P, Fletterick RJ, Guy RK. The Molecular Mechanisms of Coactivator Utilization in Ligand-dependent Transactivation by the Androgen Receptor. J Biol Chem 2005; 280:8060-8. [PMID: 15563469 DOI: 10.1074/jbc.m407046200] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Androgens drive sex differentiation, bone and muscle development, and promote growth of hormone-dependent cancers by binding the nuclear androgen receptor (AR), which recruits coactivators to responsive genes. Most nuclear receptors recruit steroid receptor coactivators (SRCs) to their ligand binding domain (LBD) using a leucine-rich motif (LXXLL). AR is believed to recruit unique coactivators to its LBD using an aromatic-rich motif (FXXLF) while recruiting SRCs to its N-terminal domain (NTD) through an alternate mechanism. Here, we report that the AR-LBD interacts with both FXXLF motifs and a subset of LXXLL motifs and that contacts with these LXXLL motifs are both necessary and sufficient for SRC-mediated AR regulation of transcription. Crystal structures of the activated AR in complex with both recruitment motifs reveal that side chains unique to the AR-LBD rearrange to bind either the bulky FXXLF motifs or the more compact LXXLL motifs and that AR utilizes subsidiary contacts with LXXLL flanking sequences to discriminate between LXXLL motifs.
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Affiliation(s)
- Eva Estébanez-Perpiñá
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, USA
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Current Awareness on Comparative and Functional Genomics. Comp Funct Genomics 2005. [PMCID: PMC2448604 DOI: 10.1002/cfg.419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
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