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Role of Peroxisome Proliferator-Activated Receptors (PPARs) in Energy Homeostasis of Dairy Animals: Exploiting Their Modulation through Nutrigenomic Interventions. Int J Mol Sci 2021; 22:ijms222212463. [PMID: 34830341 PMCID: PMC8619600 DOI: 10.3390/ijms222212463] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/31/2021] [Accepted: 11/16/2021] [Indexed: 12/22/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are the nuclear receptors that could mediate the nutrient-dependent transcriptional activation and regulate metabolic networks through energy homeostasis. However, these receptors cannot work properly under metabolic stress. PPARs and their subtypes can be modulated by nutrigenomic interventions, particularly under stress conditions to restore cellular homeostasis. Many nutrients such as polyunsaturated fatty acids, vitamins, dietary amino acids and phytochemicals have shown their ability for potential activation or inhibition of PPARs. Thus, through different mechanisms, all these nutrients can modulate PPARs and are ultimately helpful to prevent various metabolic disorders, particularly in transition dairy cows. This review aims to provide insights into the crucial role of PPARs in energy metabolism and their potential modulation through nutrigenomic interventions to improve energy homeostasis in dairy animals.
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Sharma N, Pollina EA, Nagy MA, Yap EL, DiBiase FA, Hrvatin S, Hu L, Lin C, Greenberg ME. ARNT2 Tunes Activity-Dependent Gene Expression through NCoR2-Mediated Repression and NPAS4-Mediated Activation. Neuron 2019; 102:390-406.e9. [PMID: 30846309 DOI: 10.1016/j.neuron.2019.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 11/20/2018] [Accepted: 02/04/2019] [Indexed: 12/22/2022]
Abstract
Neuronal activity-dependent transcription is tuned to ensure precise gene induction during periods of heightened synaptic activity, allowing for appropriate responses of activated neurons within neural circuits. The consequences of aberrant induction of activity-dependent genes on neuronal physiology are not yet clear. Here, we demonstrate that, in the absence of synaptic excitation, the basic-helix-loop-helix (bHLH)-PAS family transcription factor ARNT2 recruits the NCoR2 co-repressor complex to suppress neuronal activity-dependent regulatory elements and maintain low basal levels of inducible genes. This restricts inhibition of excitatory neurons, maintaining them in a state that is receptive to future sensory stimuli. By contrast, in response to heightened neuronal activity, ARNT2 recruits the neuronal-specific bHLH-PAS factor NPAS4 to activity-dependent regulatory elements to induce transcription and thereby increase somatic inhibitory input. Thus, the interplay of bHLH-PAS complexes at activity-dependent regulatory elements maintains temporal control of activity-dependent gene expression and scales somatic inhibition with circuit activity.
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Affiliation(s)
- Nikhil Sharma
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | | | - M Aurel Nagy
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Ee-Lynn Yap
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Florence A DiBiase
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Sinisa Hrvatin
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Linda Hu
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Cindy Lin
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
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Broekema MF, Hollman DAA, Koppen A, van den Ham HJ, Melchers D, Pijnenburg D, Ruijtenbeek R, van Mil SWC, Houtman R, Kalkhoven E. Profiling of 3696 Nuclear Receptor-Coregulator Interactions: A Resource for Biological and Clinical Discovery. Endocrinology 2018; 159:2397-2407. [PMID: 29718163 DOI: 10.1210/en.2018-00149] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 04/24/2018] [Indexed: 12/13/2022]
Abstract
Nuclear receptors (NRs) are ligand-inducible transcription factors that play critical roles in metazoan development, reproduction, and physiology and therefore are implicated in a broad range of pathologies. The transcriptional activity of NRs critically depends on their interaction(s) with transcriptional coregulator proteins, including coactivators and corepressors. Short leucine-rich peptide motifs in these proteins (LxxLL in coactivators and LxxxIxxxL in corepressors) are essential and sufficient for NR binding. With 350 different coregulator proteins identified to date and with many coregulators containing multiple interaction motifs, an enormous combinatorial potential is present for selective NR-mediated gene regulation. However, NR-coregulator interactions have often been determined experimentally on a one-to-one basis across diverse experimental conditions. In addition, NR-coregulator interactions are difficult to predict because the molecular determinants that govern specificity are not well established. Therefore, many biologically and clinically relevant NR-coregulator interactions may remain to be discovered. Here, we present a comprehensive overview of 3696 NR-coregulator interactions by systematically characterizing the binding of 24 nuclear receptors with 154 coregulator peptides. We identified unique ligand-dependent NR-coregulator interaction profiles for each NR, confirming many well-established NR-coregulator interactions. Hierarchical clustering based on the NR-coregulator interaction profiles largely recapitulates the classification of NR subfamilies based on the primary amino acid sequences of the ligand-binding domains, indicating that amino acid sequence is an important, although not the only, molecular determinant in directing and fine-tuning NR-coregulator interactions. This NR-coregulator peptide interactome provides an open data resource for future biological and clinical discovery as well as NR-based drug design.
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Affiliation(s)
- Marjoleine F Broekema
- Molecular Cancer Research and Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, CG Utrecht, Netherlands
| | - Danielle A A Hollman
- Molecular Cancer Research and Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, CG Utrecht, Netherlands
| | - Arjen Koppen
- Molecular Cancer Research and Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, CG Utrecht, Netherlands
| | | | - Diana Melchers
- PamGene International B. V., BJ 's-Hertogenbosch, Netherlands
| | - Dirk Pijnenburg
- PamGene International B. V., BJ 's-Hertogenbosch, Netherlands
| | - Rob Ruijtenbeek
- PamGene International B. V., BJ 's-Hertogenbosch, Netherlands
| | - Saskia W C van Mil
- Molecular Cancer Research and Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, CG Utrecht, Netherlands
| | - René Houtman
- PamGene International B. V., BJ 's-Hertogenbosch, Netherlands
| | - Eric Kalkhoven
- Molecular Cancer Research and Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, CG Utrecht, Netherlands
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Figliozzi RW, Chen F, Hsia SV. Reversing thyroid-hormone-mediated repression of a HSV-1 promoter via computationally guided mutagenesis. J Cell Sci 2017; 130:3740-3748. [PMID: 28916515 DOI: 10.1242/jcs.204222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 09/12/2017] [Indexed: 11/20/2022] Open
Abstract
Thyroid hormones (THs) and their DNA-binding nuclear receptors (TRs) direct transcriptional regulation in diverse ways depending on the host cell environment and specific promoter characteristics of TH-sensitive genes. This study sought to elucidate the impact on transcriptional repression of nucleotide sequence or orientation within TR binding sites - the TH response elements (TREs) of TH-sensitive promoters - to better understand ligand-dependent transcriptional repression of wild-type promoters. Computational analysis of the HSV-1 thymidine kinase (TK) gene TRE bound by TR and retinoid X receptor (RXR) revealed a single TRE point mutation sufficient to reverse the TRE orientation. In vitro experiments showed that the TRE point mutation had distinct impacts on promoter activity, sufficient to reverse the TH-dependent negative regulation in neuroendocrine differentiated cells. This point mutation altered the promoter's regulatory mechanism by discrete changes in transcription factor TR occupancy and altered enrichment of the repressive chromatin modification of histone-3-lysine-9-trimethyl (H3K9Me3). Insights relating to this negative TRE (nTRE) mechanism aids our understanding of other nTREs and TRE mutations associated with TH and herpes diseases.
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Affiliation(s)
- Robert W Figliozzi
- Department of Pharmaceutical Sciences, School of Pharmacy and Health Professions, University of Maryland Eastern Shore, Princess Anne, MD 21853, USA.,Department of Natural Sciences, School of Agriculture and Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD 21853, USA
| | - Feng Chen
- Department of Pharmaceutical Sciences, School of Pharmacy and Health Professions, University of Maryland Eastern Shore, Princess Anne, MD 21853, USA
| | - Shaochung V Hsia
- Department of Pharmaceutical Sciences, School of Pharmacy and Health Professions, University of Maryland Eastern Shore, Princess Anne, MD 21853, USA .,Department of Natural Sciences, School of Agriculture and Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD 21853, USA
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Lempiäinen JK, Niskanen EA, Vuoti KM, Lampinen RE, Göös H, Varjosalo M, Palvimo JJ. Agonist-specific Protein Interactomes of Glucocorticoid and Androgen Receptor as Revealed by Proximity Mapping. Mol Cell Proteomics 2017; 16:1462-1474. [PMID: 28611094 DOI: 10.1074/mcp.m117.067488] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 06/02/2017] [Indexed: 11/06/2022] Open
Abstract
Glucocorticoid receptor (GR) and androgen receptor (AR) are steroid-inducible transcription factors (TFs). The GR and the AR are central regulators of various metabolic, homeostatic and differentiation processes and hence important therapeutic targets, especially in inflammation and prostate cancer, respectively. Hormone binding to these steroid receptors (SRs) leads to DNA binding and activation or repression of their target genes with the aid of interacting proteins, coregulators. However, protein interactomes of these important drug targets have remained poorly defined. We used proximity-dependent biotin identification to map the protein interaction landscapes of GR and AR in the presence and absence of their cognate agonist (dexamethasone, 5α-dihydrotestosterone) and antagonist (RU486, enzalutamide) in intact human cells. We reproducibly identified more than 30 proteins that interacted with the GR in an agonist-specific manner and whose interactions were significantly influenced by the DNA-binding function of the receptor. Interestingly, the agonist-dependent interactome of the GR overlapped considerably with that of the AR. In addition to known coactivators, corepressors and components of BAF (SWI/SNF) chromatin-remodeling complex, we identified a number of proteins, including lysine methyltransferases and demethylases that have not been previously linked to glucocorticoid or androgen signaling. A substantial number of these novel agonist-dependent GR/AR-interacting proteins, e.g. BCOR, IRF2BP2, RCOR1, and TLE3, have previously been implicated in transcription repression. This together with our data on the effect of BCOR, IRF2BP2, and RCOR1 on GR target gene expression suggests multifaceted functions and roles for SR coregulators. These first high confidence SR interactomes will aid in therapeutic targeting of the GR and the AR.
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Affiliation(s)
- Joanna K Lempiäinen
- From the ‡Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Einari A Niskanen
- From the ‡Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Kaisa-Mari Vuoti
- From the ‡Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Riikka E Lampinen
- From the ‡Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Helka Göös
- §Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Markku Varjosalo
- §Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Jorma J Palvimo
- From the ‡Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland;
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Abstract
Nuclear receptors are transcription factors that regulate gene expression through the ligand-controlled recruitment of a diverse group of proteins known as coregulators. Most nuclear receptor coregulators function in large multi-protein complexes that modify chromatin and thereby regulate the transcription of target genes. Structural and functional studies are beginning to reveal how these complexes are assembled bringing together multiple functionalities that mediate: recruitment to specific genomic loci through interaction with transcription factors; recruitment of enzymatic activities that either modify or remodel chromatin and targeting the complexes to their chromatin substrate. These activities are regulated by post-translational modifications, alternative splicing and small signalling molecules. This review focuses on our current understanding of coregulator complexes and aims to highlight the common principles that are beginning to emerge.
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Affiliation(s)
- Christopher J. Millard
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
| | - Peter J. Watson
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
| | - Louise Fairall
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
| | - John W.R. Schwabe
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
- Correspondence to:
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Sharma P, Thakran S, Deng X, Elam MB, Park EA. Nuclear corepressors mediate the repression of phospholipase A2 group IIa gene transcription by thyroid hormone. J Biol Chem 2013; 288:16321-16333. [PMID: 23629656 DOI: 10.1074/jbc.m112.445569] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Secretory phospholipase A2 group IIa (PLA2g2a) is associated with inflammation, hyperlipidemia, and atherogenesis. Transcription of the PLA2g2a gene is induced by multiple cytokines. Here, we report the surprising observation that thyroid hormone (T3) inhibited PLA2g2a gene expression in human and rat hepatocytes as well as in rat liver. Moreover, T3 reduced the cytokine-mediated induction of PLA2g2a, suggesting that the thyroid status may modulate aspects of the inflammatory response. In an effort to dissect the mechanism of repression by T3, we cloned the PLA2g2a gene and identified a negative T3 response element in the promoter. This T3 receptor (TRβ)-binding site differed considerably from consensus T3 stimulatory elements. Using in vitro and in vivo binding assays, we found that TRβ bound directly to the PLA2g2a promoter as a heterodimer with the retinoid X receptor. Knockdown of nuclear corepressor or silencing mediator for retinoid and thyroid receptors by siRNA blocked the T3 inhibition of PLA2g2a. Using chromatin immunoprecipitation assays, we showed that nuclear corepressor and silencing mediator for retinoid and thyroid receptors were associated with the PLA2g2a gene in the presence of T3. In contrast with the established role of T3 to promote coactivator association with TRβ, our experiments demonstrate a novel inverse recruitment mechanism in which liganded TRβ recruits corepressors to inhibit PLA2g2a expression.
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Affiliation(s)
- Pragya Sharma
- Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Shalini Thakran
- Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Xiong Deng
- Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163; Department of Veterans Affairs Medical Center, Memphis, Tennessee 38163
| | - Marshall B Elam
- Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163; Department of Veterans Affairs Medical Center, Memphis, Tennessee 38163
| | - Edwards A Park
- Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163.
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Johnson AB, O'Malley BW. Steroid receptor coactivators 1, 2, and 3: critical regulators of nuclear receptor activity and steroid receptor modulator (SRM)-based cancer therapy. Mol Cell Endocrinol 2012; 348:430-9. [PMID: 21664237 PMCID: PMC3202666 DOI: 10.1016/j.mce.2011.04.021] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 04/04/2011] [Accepted: 04/22/2011] [Indexed: 01/17/2023]
Abstract
Coactivators are a diverse group of non-DNA binding proteins that induce structural changes in agonist-bound nuclear receptors (NRs) that are essential for NR-mediated transcriptional activation. Once bound, coactivators function to bridge enhancer binding proteins to the general transcription machinery, as well as to recruit secondary coactivators that modify promoter and enhancer chromatin in a manner permissive for transcriptional activation. In the following review article, we focus on one of the most in-depth studied families of coactivators, the steroid receptor coactivators (SRC) 1, 2, and 3. SRCs are widely implicated in NR-mediated diseases, especially in cancers, with the majority of studies focused on their roles in breast cancer. We highlight the relevant literature supporting the oncogenic activity of SRCs and their future as diagnostic and prognostic indicators. With much interest in the development of selective receptor modulators (SRMs), we focus on how these coactivators regulate the interactions between SRMs and their respective NRs; and, importantly, the influence that coactivators have on the functional output of SRMs. Furthermore, we speculate that coactivator-specific inhibitors could provide powerful, all-encompassing treatments that target multiple modes of oncogenic regulation in cancers resistant to typical anti-endocrine treatments.
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Affiliation(s)
- Amber B Johnson
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, United States
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Misawa H, Sasaki S, Matsushita A, Ohba K, Iwaki H, Matsunaga H, Suzuki S, Ishizuka K, Oki Y, Nakamura H. Liganded thyroid hormone receptor inhibits phorbol 12-O-tetradecanoate-13-acetate-induced enhancer activity via firefly luciferase cDNA. PLoS One 2012; 7:e28916. [PMID: 22253701 PMCID: PMC3258237 DOI: 10.1371/journal.pone.0028916] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 11/17/2011] [Indexed: 11/27/2022] Open
Abstract
Thyroid hormone receptor (TR) belongs to the nuclear hormone receptor (NHR) superfamily and regulates the transcription of its target genes in a thyroid hormone (T3)-dependent manner. While the detail of transcriptional activation by T3 (positive regulation) has been clarified, the mechanism of T3-dependent repression (negative regulation) remains to be determined. In addition to naturally occurring negative regulations typically found for the thyrotropin β gene, T3-bound TR (T3/TR) is known to cause artificial negative regulation in reporter assays with cultured cells. For example, T3/TR inhibits the transcriptional activity of the reporter plasmids harboring AP-1 site derived from pUC/pBR322-related plasmid (pUC/AP-1). Artificial negative regulation has also been suggested in the reporter assay with firefly luciferase (FFL) gene. However, identification of the DNA sequence of the FFL gene using deletion analysis was not performed because negative regulation was evaluated by measuring the enzymatic activity of FFL protein. Thus, there remains the possibility that the inhibition by T3 is mediated via a DNA sequence other than FFL cDNA, for instance, pUC/AP-1 site in plasmid backbone. To investigate the function of FFL cDNA as a transcriptional regulatory sequence, we generated pBL-FFL-CAT5 by ligating FFL cDNA in the 5' upstream region to heterologous thymidine kinase promoter in pBL-CAT5, a chloramphenicol acetyl transferase (CAT)-based reporter gene, which lacks pUC/AP-1 site. In kidney-derived CV1 and choriocarcinoma-derived JEG3 cells, pBL-FFL-CAT5, but not pBL-CAT5, was strongly activated by a protein kinase C activator, phorbol 12-O-tetradecanoate-13-acetate (TPA). TPA-induced activity of pBL-FFL-CAT5 was negatively regulated by T3/TR. Mutation of nt. 626/640 in FFL cDNA attenuated the TPA-induced activation and concomitantly abolished the T3-dependent repression. Our data demonstrate that FFL cDNA sequence mediates the TPA-induced transcriptional activity, which is inhibited by T3/TR.
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Affiliation(s)
- Hiroko Misawa
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Shigekazu Sasaki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
- * E-mail:
| | - Akio Matsushita
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Kenji Ohba
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Hiroyuki Iwaki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Hideyuki Matsunaga
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Shingo Suzuki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Keiko Ishizuka
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Yutaka Oki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Hirotoshi Nakamura
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
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Pawlak M, Lefebvre P, Staels B. General molecular biology and architecture of nuclear receptors. Curr Top Med Chem 2012; 12:486-504. [PMID: 22242852 PMCID: PMC3637177 DOI: 10.2174/156802612799436641] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 11/22/2011] [Indexed: 12/12/2022]
Abstract
Nuclear receptors (NRs) regulate and coordinate multiple processes by integrating internal and external signals, thereby maintaining homeostasis in front of nutritional, behavioral and environmental challenges. NRs exhibit strong similarities in their structure and mode of action: by selective transcriptional activation or repression of cognate target genes, which can either be controlled through a direct, DNA binding-dependent mechanism or through crosstalk with other transcriptional regulators, NRs modulate the expression of gene clusters thus achieving coordinated tissue responses. Additionally, non genomic effects of NR ligands appear mediated by ill-defined mechanisms at the plasma membrane. These effects mediate potential therapeutic effects as small lipophilic molecule targets, and many efforts have been put in elucidating their precise mechanism of action and pathophysiological roles. Currently, numerous nuclear receptor ligand analogs are used in therapy or are tested in clinical trials against various diseases such as hypertriglyceridemia, atherosclerosis, diabetes, allergies and cancer and others.
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Affiliation(s)
- Michal Pawlak
- Récepteurs nucléaires, maladies cardiovasculaires et diabète
INSERM : U1011Institut Pasteur de LilleUniversité Lille II - Droit et santé1 rue du Prof Calmette 59019 Lille Cedex,FR
| | - Philippe Lefebvre
- Récepteurs nucléaires, maladies cardiovasculaires et diabète
INSERM : U1011Institut Pasteur de LilleUniversité Lille II - Droit et santé1 rue du Prof Calmette 59019 Lille Cedex,FR
| | - Bart Staels
- Récepteurs nucléaires, maladies cardiovasculaires et diabète
INSERM : U1011Institut Pasteur de LilleUniversité Lille II - Droit et santé1 rue du Prof Calmette 59019 Lille Cedex,FR
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Sar P, Peter R, Rath B, Mohapatra AD, Mishra SK. 3, 3'5 Triiodo L thyronine induces apoptosis in human breast cancer MCF-7 cells, repressing SMP30 expression through negative thyroid response elements. PLoS One 2011; 6:e20861. [PMID: 21687737 PMCID: PMC3110202 DOI: 10.1371/journal.pone.0020861] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 05/14/2011] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Thyroid hormones regulate cell proliferation, differentiation as well as apoptosis. However molecular mechanism underlying apoptosis as a result of thyroid hormone signaling is poorly understood. The antiapoptotic role of Senescence Marker Protein-30 (SMP30) has been characterized in response to varieties of stimuli as well as in knock out model. Our earlier data suggest that thyroid hormone 3, 3'5 Triiodo L Thyronine (T(3)), represses SMP30 in rat liver. METHODOLOGY/PRINCIPAL FINDINGS In highly metastatic MCF-7, human breast cancer cell line T3 treatment repressed SMP30 expression leading to enhanced apoptosis. Analysis by flow cytometry and other techniques revealed that overexpression and silencing of SMP30 in MCF-7 resulted in decelerated and accelerated apoptosis respectively. In order to identify the cis-acting elements involved in this regulation, we have analyzed hormone responsiveness of transiently transfected hSMP30 promoter deletion reporter vectors in MCF-7 cells. As opposed to the expected epigenetic outcome, thyroid hormone down regulated hSMP30 promoter activity despite enhanced recruitment of acetylated H3 on thyroid response elements (TREs). From the stand point of established epigenetic concept we have categorised these two TREs as negative response elements. Our attempt of siRNA mediated silencing of TRβ, reduced the fold of repression of SMP30 gene expression. In presence of thyroid hormone, Trichostatin- A (TSA), which is a Histone deacetylase (HDAC) inhibitor further inhibited SMP30 promoter activity. The above findings are in support of categorisation of both the thyroid response element as negative response elements as usually TSA should have reversed the repressions. CONCLUSION This is the first report of novel mechanistic insights into the remarkable downregulation of SMP30 gene expression by thyroid hormone which in turn induces apoptosis in MCF-7 human breast cancer cells. We believe that our study represents a good ground for future effort to develop new therapeutic approaches to challenge the progression of breast cancer.
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Affiliation(s)
- Pranati Sar
- Cancer Biology Lab, Department of Gene Function and Regulation, Institute of Life Sciences, Chandrasekharpur, Bhubaneswar, India
| | - Rosalima Peter
- Cancer Biology Lab, Department of Gene Function and Regulation, Institute of Life Sciences, Chandrasekharpur, Bhubaneswar, India
| | - Bandita Rath
- Cancer Biology Lab, Department of Gene Function and Regulation, Institute of Life Sciences, Chandrasekharpur, Bhubaneswar, India
| | - Alok Das Mohapatra
- Vector Born Disease Lab, Department of Infectious Disease Biology, Institute of Life Sciences, Chandrasekharpur, Bhubaneswar, India
| | - Sandip K. Mishra
- Cancer Biology Lab, Department of Gene Function and Regulation, Institute of Life Sciences, Chandrasekharpur, Bhubaneswar, India
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12
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Santos GM, Fairall L, Schwabe JW. Negative regulation by nuclear receptors: a plethora of mechanisms. Trends Endocrinol Metab 2011; 22:87-93. [PMID: 21196123 PMCID: PMC3053446 DOI: 10.1016/j.tem.2010.11.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 11/29/2010] [Accepted: 11/30/2010] [Indexed: 10/30/2022]
Abstract
Nuclear receptors are arguably the best understood transcriptional regulators. We know a great deal about the mechanisms through which they activate transcription in response to ligand binding and about the mechanisms through which they repress transcription in the absence of ligand. However, endocrine regulation often requires that ligand-bound receptors repress transcription of a subset of genes. An understanding of the mechanism for ligand-induced repression and how this differs from activation has proven elusive. A number of recent studies have directly or indirectly addressed this problem. Yet it seems the more evidence that accumulates, the more complex the mystery becomes.
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Affiliation(s)
| | - Louise Fairall
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Lancaster Road, Leicester, LE1 9HN, UK
| | - John W.R. Schwabe
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Lancaster Road, Leicester, LE1 9HN, UK
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13
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Adhikary T, Kaddatz K, Finkernagel F, Schönbauer A, Meissner W, Scharfe M, Jarek M, Blöcker H, Müller-Brüsselbach S, Müller R. Genomewide analyses define different modes of transcriptional regulation by peroxisome proliferator-activated receptor-β/δ (PPARβ/δ). PLoS One 2011; 6:e16344. [PMID: 21283829 PMCID: PMC3023804 DOI: 10.1371/journal.pone.0016344] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 12/11/2010] [Indexed: 11/26/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors with essential functions in lipid, glucose and energy homeostasis, cell differentiation, inflammation and metabolic disorders, and represent important drug targets. PPARs heterodimerize with retinoid X receptors (RXRs) and can form transcriptional activator or repressor complexes at specific DNA elements (PPREs). It is believed that the decision between repression and activation is generally governed by a ligand-mediated switch. We have performed genomewide analyses of agonist-treated and PPARβ/δ-depleted human myofibroblasts to test this hypothesis and to identify global principles of PPARβ/δ-mediated gene regulation. Chromatin immunoprecipitation sequencing (ChIP-Seq) of PPARβ/δ, H3K4me3 and RNA polymerase II enrichment sites combined with transcriptional profiling enabled the definition of 112 bona fide PPARβ/δ target genes showing either of three distinct types of transcriptional response: (I) ligand-independent repression by PPARβ/δ; (II) ligand-induced activation and/or derepression by PPARβ/δ; and (III) ligand-independent activation by PPARβ/δ. These data identify PPRE-mediated repression as a major mechanism of transcriptional regulation by PPARβ/δ, but, unexpectedly, also show that only a subset of repressed genes are activated by a ligand-mediated switch. Our results also suggest that the type of transcriptional response by a given target gene is connected to the structure of its associated PPRE(s) and the biological function of its encoded protein. These observations have important implications for understanding the regulatory PPAR network and PPARβ/δ ligand-based drugs.
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Affiliation(s)
- Till Adhikary
- Institute of Molecular Biology and Tumor Research (IMT), Philipps University, Marburg, Germany
| | - Kerstin Kaddatz
- Institute of Molecular Biology and Tumor Research (IMT), Philipps University, Marburg, Germany
| | - Florian Finkernagel
- Institute of Molecular Biology and Tumor Research (IMT), Philipps University, Marburg, Germany
| | - Anne Schönbauer
- Institute of Molecular Biology and Tumor Research (IMT), Philipps University, Marburg, Germany
| | - Wolfgang Meissner
- Institute of Molecular Biology and Tumor Research (IMT), Philipps University, Marburg, Germany
| | - Maren Scharfe
- Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Michael Jarek
- Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Helmut Blöcker
- Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | | | - Rolf Müller
- Institute of Molecular Biology and Tumor Research (IMT), Philipps University, Marburg, Germany
- * E-mail:
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14
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Thyroid hormone receptor β1 domains responsible for the antagonism with the ras oncogene: role of corepressors. Oncogene 2010; 30:854-64. [DOI: 10.1038/onc.2010.464] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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15
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Chan IH, Privalsky ML. Thyroid hormone receptor mutants implicated in human hepatocellular carcinoma display an altered target gene repertoire. Oncogene 2009; 28:4162-74. [PMID: 19749797 PMCID: PMC2787677 DOI: 10.1038/onc.2009.265] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Thyroid hormone receptors (TRs) are hormone-regulated transcription factors that control multiple aspects of normal physiology and development. Mutations in TRs have been identified at high frequency in certain cancers, including human hepatocellular carcinomas (HCCs). The majority of HCC-TR mutants bear lesions within their DNA recognition domains, and we have hypothesized that these lesions change the mutant receptors' target gene repertoire in a way crucial to their function as oncoproteins. Using stable cell transformants and expression array analysis, we determined that mutant TRs isolated from two different HCCs do, as hypothesized, display a target gene repertoire distinct from that of their normal TR progenitors. Only a subset of genes regulated by wild-type TRs was regulated by the corresponding HCC-TR mutants. More surprisingly, the HCC-TR mutants also gained the ability to regulate additional target genes not recognized by the wild-type receptors, and were not simply restricted to repression, but could also activate a subset of their target genes. We conclude that the TR mutants isolated from HCC have sustained multiple alterations from their normal progenitors that include not only changes in their transcriptional outputs, but also changes in the genes they target; both are likely to contribute to neoplasia.
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Affiliation(s)
- I H Chan
- Department of Microbiology, College of Biological Sciences, University of California at Davis, Davis, CA 95616, USA
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16
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Lu Y, Bratton S, Heydel JM, Radominska-Pandya A. Effect of Retinoids on UDP-Glucuronosyltransferase 2B7 mRNA Expression in Caco-2 Cells. Drug Metab Pharmacokinet 2008; 23:364-72. [DOI: 10.2133/dmpk.23.364] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Lonard DM, O'malley BW. Nuclear receptor coregulators: judges, juries, and executioners of cellular regulation. Mol Cell 2007; 27:691-700. [PMID: 17803935 DOI: 10.1016/j.molcel.2007.08.012] [Citation(s) in RCA: 352] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In a little more than 10 years, nuclear receptor (NR) coregulators (coactivators and corepressors) have contributed to our present realization that a great level of sophistication exists in transcriptional regulation. Here, we discuss the implications of coregulators as versatile regulatory agents, influencing not only transcriptional initiation but also elongation, splicing, and translation. In addition to this, there is an increasing recognition that they also regulate a variety of biological processes outside of the nucleus. An important concept that we wish to emphasize is that coregulators are both targets and propagators of posttranslational modification (PTM) codes. This underlies a sophisticated epigenetic regulatory scheme from which a complex and dynamic mammalian phenotype emanates.
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Affiliation(s)
- David M Lonard
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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18
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Peterson TJ, Karmakar S, Pace MC, Gao T, Smith CL. The silencing mediator of retinoic acid and thyroid hormone receptor (SMRT) corepressor is required for full estrogen receptor alpha transcriptional activity. Mol Cell Biol 2007; 27:5933-48. [PMID: 17591692 PMCID: PMC1952168 DOI: 10.1128/mcb.00237-07] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Multiple factors influence estrogen receptor alpha (ERalpha) transcriptional activity. Current models suggest that the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT) corepressor functions within a histone deactylase-containing protein complex that binds to antiestrogen-bound ERalpha and contributes to negative regulation of gene expression. In this report, we demonstrate that SMRT is required for full agonist-dependent ERalpha activation. Chromatin immunoprecipitation assays demonstrate that SMRT, like ERalpha and the SRC-3 coactivator, is recruited to an estrogen-responsive promoter in estrogen-treated MCF-7 cells. Depletion of SMRT, but not histone deacetylases 1 or 3, negatively impacts estradiol-stimulated ERalpha transcriptional activity, while exogenous expression of SMRT's receptor interaction domains blocks ERalpha activity, indicating a functional interaction between this corepressor and agonist-bound ERalpha. Stimulation of estradiol-induced ERalpha activity by SMRT overexpression occurred in HeLa and MCF-7 cells, but not HepG2 cells, indicating that these positive effects are cell type specific. Similarly, the ability of SMRT depletion to promote the agonist activity of tamoxifen was observed for HeLa but not MCF-7 cells. Furthermore, impairment of agonist-stimulated activity by SMRT depletion is specific to ERalpha and not observed for receptors for vitamin D, androgen, or thyroid hormone. Nuclear receptor corepressor (N-CoR) depletion increased the transcriptional activity of all four tested receptors. SMRT is required for full expression of the ERalpha target genes cyclin D1, BCL-2, and progesterone receptor but not pS2, and its depletion significantly attenuated estrogen-dependent proliferation of MCF-7 cells. Taken together, these data indicate that SMRT, in conjunction with gene-specific and cell-dependent factors, is required for positively regulating agonist-dependent ERalpha transcriptional activity.
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Affiliation(s)
- Theresa J Peterson
- Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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19
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Santos GM, Afonso V, Barra GB, Togashi M, Webb P, Neves FAR, Lomri N, Lomri A. Negative Regulation of Superoxide Dismutase-1 Promoter by Thyroid Hormone. Mol Pharmacol 2006; 70:793-800. [PMID: 16738222 DOI: 10.1124/mol.106.025627] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The role of thyroid hormone [L-3,5,3'-triiodothyronine (T3)] and the thyroid hormone receptor (TR) in regulating growth, development, and metabolic homeostasis is well established. It is also emerging that T3 is associated with oxidative stress through the regulation of the activity of superoxide dismutase-1 (SOD-1), a key enzyme in the metabolism of oxygen free radicals. We found that T3 reverses the activation of the SOD-1 promoter caused by the free radical generators paraquat and phorbol 12-myristate 13-acetate through the direct repression of the SOD-1 promoter by liganded TR. Conversely, the SOD-1 promoter is significantly stimulated by unliganded TRs. This regulation requires the DNA-binding domain of the TR, which is recruited to an inhibitory element between -157 and +17 of the SOD-1 promoter. TR mutations, which abolish recruitment of coactivator proteins, block repression of the SOD-1 promoter. Conversely, a mutation that inhibits corepressor binding to the TR prevents activation. Together, our findings suggest a mechanism of negative regulation in which TR binds to the SOD-1 promoter but coactivator and corepressor binding surfaces have an inverted function. This effect may be important in T3 induction of oxidative stress in thyroid hormone excess.
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Affiliation(s)
- Guilherme M Santos
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 606, Lariboisiere Hospital, 2, rue Ambroise Paré, 75475 Paris Cedex 10, France
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20
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Malartre M, Short S, Sharpe C. Xenopus embryos lacking specific isoforms of the corepressor SMRT develop abnormal heads. Dev Biol 2006; 292:333-43. [PMID: 16500640 DOI: 10.1016/j.ydbio.2006.01.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Revised: 12/22/2005] [Accepted: 01/07/2006] [Indexed: 11/18/2022]
Abstract
The corepressor SMRT acts on a range of transcription factors, including the retinoid and thyroid hormone nuclear receptors. The carboxy-terminal region of SMRT contains CoRNR box motifs that mediate these interactions. We have shown, in Xenopus, that SMRT can exist as isoforms containing either two or three CoRNR boxes depending on the alternative splicing of exon 37b. The number of SMRT transcript isoforms expressed increases during development until all sixteen possible isoforms are identified in the swimming tadpole. To eliminate specific SMRT isoforms, we have developed a process that uses an antisense morpholino oligonucleotide in Xenopus to dictate the outcome of alternative splicing at a defined exon and used this to inhibit the formation of transcripts containing exon 37b. These embryos are therefore limited to the expression of SMRT isoforms that contain two rather than three CoRNR boxes. Analysis of responsive genes in these embryos shows that targets of thyroid hormone, but not retinoid signaling are affected by the elimination of exon 37b. Morpholino-injected embryos have swimming abnormalities and develop altered head morphology, an expanded olfactory epithelium and disorganized peripheral axons. These experiments indicate a critical role for the alternative splicing of SMRT in development.
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Affiliation(s)
- Marianne Malartre
- School of Biological Sciences, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, PO1 2DY, UK
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21
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van der Laan S, Lachize SB, Schouten TG, Vreugdenhil E, de Kloet ER, Meijer OC. Neuroanatomical distribution and colocalisation of nuclear receptor corepressor (N-CoR) and silencing mediator of retinoid and thyroid receptors (SMRT) in rat brain. Brain Res 2005; 1059:113-21. [PMID: 16212947 DOI: 10.1016/j.brainres.2005.08.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2005] [Revised: 08/03/2005] [Accepted: 08/05/2005] [Indexed: 01/17/2023]
Abstract
The two structurally related nuclear receptor corepressor (N-CoR) and silencing mediator of retinoid and thyroid receptors (SMRT) proteins have been found to differentially affect the transcriptional activity of numerous nuclear receptors, such as thyroid hormone, retinoic acid and steroid receptors. Because of the numerous effects mediated by nuclear receptors in brain, it is of interest to extend these in vitro data and to explore the cellular distribution of both corepressors in brain tissue. We therefore examined, using in situ hybridisation, whether the relative abundance of these two functionally distinct corepressors differed in rat brain and pituitary. We find that although both N-CoR and SMRT transcripts are ubiquitously expressed in brain, striking differences in their respective levels of expression could be observed in discrete areas of brain stem, thalamus, hypothalamus and hippocampus. Using dual-label immunofluorescence, we examined in selected glucocorticoid sensitive areas involved in the regulation of the hypothalamus-pituitary-adrenal axis activity, the respective protein abundance of N-CoR and SMRT. Protein abundance was largely concurrent with the mRNA expression levels, with SMRT relatively more abundant in hypothalamus and brain stem areas. Colocalisation of N-CoR and SMRT was demonstrated by confocal microscopy in most areas studied. Taken together, these findings are consistent with the idea that the uneven neuroanatomical distribution of N-CoR and SMRT protein may contribute to the site-specific effects exerted by hormones, such as glucocorticoids, in the brain.
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Affiliation(s)
- S van der Laan
- Division of Medical Pharmacology, Leiden/Amsterdam Centre for Drug Research and Leiden University Medical Center, The Netherlands.
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22
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Ortiga-Carvalho TM, Shibusawa N, Nikrodhanond A, Oliveira KJ, Machado DS, Liao XH, Cohen RN, Refetoff S, Wondisford FE. Negative regulation by thyroid hormone receptor requires an intact coactivator-binding surface. J Clin Invest 2005; 115:2517-23. [PMID: 16100573 PMCID: PMC1184039 DOI: 10.1172/jci24109] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Accepted: 05/31/2005] [Indexed: 11/17/2022] Open
Abstract
Thyroid hormone (TH) action is mediated by TH receptors (TRs), which are members of the nuclear hormone receptor superfamily. In vitro studies have demonstrated that TR activity is regulated by interactions with corepressor and coactivator proteins (CoRs and CoAs, respectively). TH stimulation is thought to involve dissociation of CoRs and recruitment of CoAs to the liganded TR. In contrast, negative regulation by TH is thought to occur via recruitment of CoRs to the liganded TR. The physiological role of CoAs bound to TRs, however, has yet to be defined. In this study, we used gene-targeting techniques to mutate the TR-beta locus within its activation function-2 (AF-2) domain (E457A). This mutation was chosen because it completely abolished CoA recruitment in vitro, while preserving normal triiodothyronine (T3) binding and CoR interactions. As expected, TH-stimulated gene expression was reduced in homozygous E457A mice. However, these animals also displayed abnormal regulation of the hypothalamic-pituitary-thyroid axis. Serum thyroxine, T3, and thyroid-stimulating hormone (TSH) levels and pituitary Tshb mRNA levels were inappropriately elevated compared with those of WT animals, and L-T3 treatment failed to suppress serum TSH and pituitary Tshb mRNA levels. Therefore, the AF-2 domain of TR-beta is required for positive and, paradoxically, for negative regulation by TH in vivo.
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Affiliation(s)
- Tania M Ortiga-Carvalho
- Department of Medicine and Committee on Molecular Metabolism and Nutrition, Pritzker School of Medicine, The University of Chicago, Chicago, Illinois, USA
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23
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Song Y, Ren J, Li SJ, Ma JW, Huang LS. Assignment of the porcine silencing mediator for retinoid and thyroid hormone receptors (NCOR2) to SSC14q21 by radiation hybrid mapping. Anim Genet 2005; 36:269. [PMID: 15932418 DOI: 10.1111/j.1365-2052.2005.01280.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Y Song
- Key Laboratory for Animal Biotechnology of Jiangxi Province and the Ministry of Agriculture of China, Jiangxi Agricultural University, Nanchang 330045, China
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24
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Meng X, Webb P, Yang YF, Shuen M, Yousef AF, Baxter JD, Mymryk JS, Walfish PG. E1A and a nuclear receptor corepressor splice variant (N-CoRI) are thyroid hormone receptor coactivators that bind in the corepressor mode. Proc Natl Acad Sci U S A 2005; 102:6267-72. [PMID: 15849266 PMCID: PMC1088377 DOI: 10.1073/pnas.0501491102] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Unliganded thyroid hormone (TH) receptors (TRs) and other nuclear receptors (NRs) repress transcription of hormone-activated genes by recruiting corepressors (CoRs), such as NR CoR (N-CoR) and SMRT. Unliganded TRs also activate transcription of TH-repressed genes. Some evidence suggests that these effects also involve TR/CoR contacts; however, the precise reasons that CoRs activate transcription in these contexts are obscure. Unraveling these mechanisms is complicated by the fact that it is difficult to decipher direct vs. indirect effects of TR-coregulator contacts in mammalian cells. In this study, we used yeast, Saccharomyces cerevisiae, which lack endogenous NRs and NR coregulators, to determine how unliganded TRs can activate transcription. We previously showed that adenovirus 5 early-region 1A coactivates unliganded TRs in yeast, and that these effects are blocked by TH. We show here that human adenovirus type 5 early region 1A (E1A) contains a short peptide (LDQLIEEVL amino acids 20-28) that resembles CoR-NR interaction motifs (CoRNR boxes), and that this motif is required for TR binding and coactivation. Although full-length N-CoR does not coactivate TR in yeast, a naturally occurring N-CoR variant (N-CoR(I)) and an artificial N-CoR truncation (N-CoR(C)) that retain CoRNR boxes but lack N-terminal repressor domains behave as potent and direct TH-repressed coactivators for unliganded TRs. We conclude that E1A and N-CoR(I) are naturally occurring TR coactivators that bind in the typical CoR mode and suggest that similar factors could mediate transcriptional activation by unliganded TRs in mammals.
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Affiliation(s)
- Xianwang Meng
- Department of Medicine, Endocrine Division, Mount Sinai Hospital, University of Toronto Medical School, Toronto, ON, Canada M5G 1X5
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25
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Kim SW, Ho SC, Hong SJ, Kim KM, So EC, Christoffolete M, Harney JW. A Novel Mechanism of Thyroid Hormone-dependent Negative Regulation by Thyroid Hormone Receptor, Nuclear Receptor Corepressor (NCoR), and GAGA-binding Factor on the Rat CD44 Promoter. J Biol Chem 2005; 280:14545-55. [PMID: 15701601 DOI: 10.1074/jbc.m411517200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
CD44 is an adhesion molecule in the extracellular matrix that shows various functions, including tumor genesis and metastasis. A recent study showed that CD44 expression level was strongly correlated with the generation of papillary thyroid carcinomas, the most prevalent malignancy of the thyroid gland. We report here that CD44 is negatively regulated by thyroid hormone (T(3)) through a novel mechanism. We demonstrate that nuclear receptor corepressor (NCoR) enhances thyroid hormone receptor (TR)-mediated basal transactivation by a weak TR.DNA interaction in the absence of T(3), which is repressed by T(3) through a transient TR .DNA interaction. Initially, we identified that CD44 was negatively directly transcriptionally T(3) -responsive. Deletion and mutation analysis indicated that both a weak TR and a GAGA-binding factor (GAF) binding sites on the CD44 promoter were required for negative regulation by T(3). The weak TR.DNA interaction was further confirmed by electrophoretic gel mobility shift assay, chromatin immunoprecipitation, and transfection assays using a non-DNA-binding TRalpha1 mutant. More interestingly, NCoR acted as a co-activator to enhance TR-mediated basal transactivation in the absence of T(3). This effect was eliminated by removal of TR or NCoR binding. Most strikingly, T(3) induced a remarkable increase in TR.DNA binding at 40-60 min after T(3) exposure that rapidly returned to basal levels, suggesting a T(3)-induced remodeling of chromatin structure at the early stage of T(3) stimulation resulting in repression. Therefore, we propose a mechanism by which NCoR, GAF, and TR interact with the CD44 negative T(3)-responsive element to enhance basal transactivation, whereas T(3) induces the remodeling of chromatin structure for repression.
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Affiliation(s)
- Sung-Woo Kim
- Thyroid Section, Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Institute of Medicine, Boston, Massachusetts 02115, USA.
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26
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Abstract
Gene silencing is an essential transcriptional regulatory process. Co-repressors mediate gene repression through their recruitment by DNA bound transcriptional silencer proteins. Co-repressors repress gene expression through several mechanisms, mostly investigated on the level of chromatin. Lack or aberrant gene silencing is associated with many defects both on cellular and organismic level. Several human diseases are based on dysregulated co-repressor binding to transcriptional silencers indicating that co-repressor recruitment and the strength of gene silencing must be under strict control. In line with that gene silencing is important for animal development, cellular proliferation and transformation. Co-repressors play also a major role in the treatment of hormone-dependent growing cancers, such as for breast and prostate cancer therapy. The molecular basis of anti-hormone therapy lies in the recruitment of co-repressors to the estrogen or androgen receptors, respectively, which leads to their inactivation and to inhibition of cancer growth. The molecular mechanisms of selected topics are summarized here.
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Affiliation(s)
- Aria Baniahmad
- Institute of Human Genetics and Anthropology, Medical Department, Friedrich-Schiller-University, 07740 Jena, Germany.
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27
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Czarnecka-Verner E, Pan S, Salem T, Gurley WB. Plant class B HSFs inhibit transcription and exhibit affinity for TFIIB and TBP. PLANT MOLECULAR BIOLOGY 2004; 56:57-75. [PMID: 15604728 DOI: 10.1007/s11103-004-2307-3] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Plant heat shock transcription factors (HSFs) are capable of transcriptional activation (class A HSFs) or both, activation and repression (class B HSFs). However, the details of mechanism still remain unclear. It is likely, that the regulation occurs through interactions of HSFs with general transcription factors (GTFs), as has been described for numerous other transcription factors. Here, we show that class A HSFs may activate transcription through direct contacts with TATA-binding protein (TBP). Class A HSFs can also interact weakly with TFIIB. Conversely, class B HSFs inhibit promoter activity through an active mechanism of repression that involves the C-terminal regulatory region (CTR) of class B HSFs. Deletion analysis revealed two sites in the CTR of soybean GmHSFB1 potentially involved in protein-protein interactions with GTFs: one is the repressor domain (RD) located in the N-terminal half of the CTR, and the other is a TFIIB binding domain (BD) that shows affinity for TFIIB and is located C-terminally from the RD. A Gal4 DNA binding domain-RD fusion repressed activity of LexA-activators, while Gal4-BD proteins synergistically activated strong and weak transcriptional activators. In vitro binding studies were consistent with this pattern of activity since the BD region alone interacted strongly with TFIIB, and the presence of RD had an inhibitory effect on TFIIB binding and transcriptional activation.
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Affiliation(s)
- Eva Czarnecka-Verner
- Microbiology and Cell Science Department, Program of Plant Molecular and Cellular Biology, University of Florida, Bldg. 981, Gainesville, FL 32611-0700, USA.
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28
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Côté S, McNamara S, Brambilla D, Bianchini A, Rizzo G, del Rincón SV, Grignani F, Nervi C, Miller WH. Expression of SMRTbeta promotes ligand-induced activation of mutated and wild-type retinoid receptors. Blood 2004; 104:4226-35. [PMID: 15319284 DOI: 10.1182/blood-2003-10-3583] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nuclear receptors are ligand-modulated transcription factors regulated by interactions with corepressors and coactivators, whose functions are not fully understood. Acute promyelocytic leukemia (APL) is characterized by a translocation, t(15;17), that produces a PML/RARalpha fusion oncoprotein, whose abnormal transcriptional function is successfully targeted by pharmacologic levels of all-trans-retinoic acid (ATRA). Mutations in the ligand-binding domain of PML/RARalpha that confer resistance to ATRA have been studied by expression in nonhematopoietic cells, such as Cos-1. Here, we show that ATRA binding and transcriptional activation by the same PML/RARalpha mutant differ markedly between nonhematopoietic and leukemic cell lines. Differential expression of the corepressor isoform silencing mediator for retinoid and thyroid receptors beta (SMRTbeta) correlates with increased ligand binding and transcription by the mutant PML/RARalpha. Transient and stable overexpression of SMRTbeta in hematopoietic cells that only express SMRTalpha increased ATRA binding, ligand-induced transcription, and ATRA-induced cell differentiation. This effect may not be limited to abnormal nuclear receptors, because overexpression of SMRTbeta increased ATRA-induced binding and transcriptional activation of wild-type receptors PML/RARalpha and RARalpha. Our results suggest a novel role for the SMRTbeta isoform whereby its cell-specific expression may influence the binding and transcriptional capacities of nuclear receptors, thus providing new evidence of distinct functions of corepressor isoforms and adding complexity to transcriptional regulation.
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MESH Headings
- Cell Line, Tumor
- Chromosomes, Human, Pair 15
- Chromosomes, Human, Pair 17
- DNA-Binding Proteins/genetics
- Drug Resistance, Neoplasm
- Gene Expression Regulation, Neoplastic/genetics
- Humans
- Jurkat Cells
- Leukemia, Promyelocytic, Acute/genetics
- Ligands
- Neoplasm Proteins/genetics
- Nuclear Receptor Co-Repressor 2
- Oncogene Proteins, Fusion/genetics
- Plasmids
- Receptors, Retinoic Acid/genetics
- Repressor Proteins/genetics
- Transcriptional Activation
- Translocation, Genetic
- Tretinoin/pharmacokinetics
- Tretinoin/toxicity
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Affiliation(s)
- Sylvie Côté
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, 3755, Chemin de la Côte Ste-Catherine, Montreal, Quebec, Canada H3T 1E2
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29
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Ishii S, Yamada M, Satoh T, Monden T, Hashimoto K, Shibusawa N, Onigata K, Morikawa A, Mori M. Aberrant dynamics of histone deacetylation at the thyrotropin-releasing hormone gene in resistance to thyroid hormone. Mol Endocrinol 2004; 18:1708-20. [PMID: 15131262 DOI: 10.1210/me.2004-0067] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Histone acetylation status influences transcriptional activity, and the mechanism of negative gene regulation by thyroid hormone remains unclear, although its impairment by a mutant thyroid hormone receptor (TR) is critical for resistance to thyroid hormone (RTH). We found a novel RTH mutant, F455S, that exhibited impaired repression of the TRH gene and had a strong dominant-negative effect on the gene. F455S strongly interacted with nuclear receptor corepressor (NCoR) and was hard to dissociate from it. To analyze the dynamics of histone acetylation status in vivo, we established cell lines stably expressing the TRH promoter and wild-type or F455S TR. Treatment with a histone deacetylase (HDAC) inhibitor completely abolished the repression of the gene by T3. The histones H3 and H4 at the TRH promoter were acetylated, and addition of T3 caused recruitment of HDACs 2 and 3 within 15 min, resulting in a transient deacetylation of the histone tails. TR and NCoR were located on the promoter, and T3 caused NCoR dissociation and steroid receptor coactivator-1 recruitment. In the presence of F455S, the histones were hyperacetylated, and HDAC recruitment and histone deacetylation were significantly impaired. This is the first report demonstrating the direct involvement of aberrant dynamics of chromatin modification in RTH.
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Affiliation(s)
- S Ishii
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan
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30
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Abstract
Nuclear receptors (also known as nuclear hormone receptors) are hormone-regulated transcription factors that control many important physiological and developmental processes in animals and humans. Defects in receptor function result in disease. The diverse biological roles of these receptors reflect their surprisingly versatile transcriptional properties, with many receptors possessing the ability to both repress and activate target gene expression. These bipolar transcriptional properties are mediated through the interactions of the receptors with two distinct classes of auxiliary proteins: corepressors and coactivators. This review focuses on how corepressors work together with nuclear receptors to repress gene transcription in the normal organism and on the aberrations in this process that lead to neoplasia and endocrine disorders. The actions of coactivators and the contributions of the same corepressors to the functions of nonreceptor transcription factors are also touched on.
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Affiliation(s)
- Martin L Privalsky
- Section of Microbiology, Division of Biological Sciences, University of California, Davis, California 95616, USA.
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31
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Abstract
The thyroid hormone receptors (TR) are able to bind DNA and to repress transcription in the absence of thyroid hormone. This repression function is an important feature of TRs as aberrant silencing can lead to severe diseases and developmental abnormalities. TR utilizes different mechanisms to achieve repression of target genes including the recruitment of cofactors called corepressors and interference with the basal transcriptional machinery. Recent studies have revealed an important role of chromatin in TR silencing involving different histone modifications and the responsible enzymes. Furthermore, the transcriptional properties of TR depend on the type of the TR DNA-binding elements. This review will focus on the molecular basis of gene silencing by TR and diseases caused by aberrant functioning.
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Affiliation(s)
- Maren Eckey
- Genetic Institute, Justus-Liebig-University, Heinrich-Buff-Ring 58-62, D-35392 Giessen, Germany
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32
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Dotzlaw H, Papaioannou M, Moehren U, Claessens F, Baniahmad A. Agonist-antagonist induced coactivator and corepressor interplay on the human androgen receptor. Mol Cell Endocrinol 2003; 213:79-85. [PMID: 15062576 DOI: 10.1016/j.mce.2003.10.036] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The human androgen receptor (AR) is a member of the nuclear hormone receptor superfamily. However, in contrast to other members of this family the amino-(N)-terminus of AR harbors the major transactivation function. Previously we have shown that hormone antagonists that bind to the carboxy-terminal ligand-binding domain repress AR through recruitment of corepressors that are recruited to the receptor N-terminus. Here we show by a modified mammalian two-hybrid system that both the AR interacting domains of the coactivator SRC1 and of the corepressor SMRT compete for interaction with the AR N-terminus. In contrast to other members of the nuclear receptor superfamily the LXXLL motifs of SRC1e are not required for this interaction, instead a stretch of 135 amino acids of the glutamine rich region (Qr) of SRC1e is essential to bind to the AR N-terminus. We show that the Qr-region of SRC1 is able to inhibit the interaction of SMRT with AR. Also, we demonstrate that the corepressor mediated repression decreases the antagonist-induced transactivation while, surprisingly, it increases the agonist-induced transactivation. This may indicate that coactivators and corepressors act in concert to dictate the overall receptor-mediated action dependent on the type of ligand.
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Affiliation(s)
- Helmut Dotzlaw
- Genetic Institute, Justus-Liebig-University, Heinrich-Buff-Ring 58-62, D-35392 Giessen, Germany
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