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Yang Y, Valdés-Rives SA, Liu Q, Gao T, Burudpakdee C, Li Y, Tan J, Tan Y, Koch CA, Rong Y, Houser SR, Wei S, Cai KQ, Wu J, Cheng SY, Wechsler-Reya R, Yang ZJ. Thyroid hormone suppresses medulloblastoma progression through promoting terminal differentiation of tumor cells. Cancer Cell 2024; 42:1434-1449.e5. [PMID: 39137728 DOI: 10.1016/j.ccell.2024.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 06/10/2024] [Accepted: 07/17/2024] [Indexed: 08/15/2024]
Abstract
Hypothyroidism is commonly detected in patients with medulloblastoma (MB). However, whether thyroid hormone (TH) contributes to MB pathogenicity remains undetermined. Here, we find that TH plays a critical role in promoting tumor cell differentiation. Reduction in TH levels frees the TH receptor, TRα1, to bind to EZH2 and repress expression of NeuroD1, a transcription factor that drives tumor cell differentiation. Increased TH reverses EZH2-mediated repression of NeuroD1 by abrogating the binding of EZH2 and TRα1, thereby stimulating tumor cell differentiation and reducing MB growth. Importantly, TH-induced differentiation of tumor cells is not restricted by the molecular subgroup of MB, suggesting that TH can be used to broadly treat MB subgroups. These findings establish an unprecedented association between TH signaling and MB pathogenicity, providing solid evidence for TH as a promising modality for MB treatment.
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Affiliation(s)
- Yijun Yang
- Nuclear Dynamics and Cancer Program, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA; Cancer Epigenetic Institute, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA
| | - Silvia Anahi Valdés-Rives
- Nuclear Dynamics and Cancer Program, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA; Cancer Epigenetic Institute, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA
| | - Qing Liu
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Tong Gao
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA
| | - Chakkapong Burudpakdee
- Nuclear Dynamics and Cancer Program, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA; Cancer Epigenetic Institute, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA
| | - Yuzhe Li
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Jun Tan
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yinfei Tan
- Department of Pathology, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA
| | - Christian A Koch
- Department of Medicine, Division of Endocrinology, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA
| | - Yuan Rong
- Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine, Temple University Health System, Philadelphia, PA 19140, USA
| | - Steven R Houser
- Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University Health System, Philadelphia, PA 19140, USA
| | - Shuanzeng Wei
- Department of Pathology, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA
| | - Kathy Q Cai
- Histopathology Facility, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA
| | - Jinhua Wu
- Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA
| | - Sheue-Yann Cheng
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Robert Wechsler-Reya
- Brain Tumor Research, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY 10032, USA
| | - Zeng-Jie Yang
- Nuclear Dynamics and Cancer Program, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA; Cancer Epigenetic Institute, Fox Chase Cancer Center, Temple University Health System, Philadelphia, PA 19111, USA.
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Yang Y, Valdés-Rives SA, Liu Q, Li Y, Tan J, Tan Y, Koch CA, Rong Y, Houser SR, Wei S, Cai KQ, Cheng SY, Curran T, Wechsler-Reya R, Yang ZJ. Thyroid Hormone Suppresses Medulloblastoma Progression Through Promoting Terminal Differentiation of Tumor Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.13.580111. [PMID: 38405864 PMCID: PMC10888774 DOI: 10.1101/2024.02.13.580111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Hypothyroidism is commonly detected in patients with medulloblastoma (MB). A possible link between thyroid hormone (TH) signaling and MB pathogenicity has not been reported. Here, we find that TH plays a critical role in promoting tumor cell differentiation. Reduction in TH levels frees the TH receptor, TRα1, to bind to EZH2 and repress expression of NeuroD1, a transcription factor that drives tumor cell differentiation. Increased TH reverses EZH2-mediated repression of NeuroD1 by abrogating the binding of EZH2 and TRα1, thereby stimulating tumor cell differentiation and reducing MB growth. Importantly, TH-induced differentiation of tumor cells is not restricted by the molecular subgroup of MB. These findings establish an unprecedented association between TH signaling and MB pathogenicity, providing solid evidence for TH as a promising modality for MB treatment.
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Kaposi's Sarcoma-Associated Herpesvirus LANA Modulates the Stability of the E3 Ubiquitin Ligase RLIM. J Virol 2020; 94:JVI.01578-19. [PMID: 31801865 DOI: 10.1128/jvi.01578-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 11/26/2019] [Indexed: 11/20/2022] Open
Abstract
The Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded latency-associated nuclear antigen (LANA) protein functions in latently infected cells as an essential participant in KSHV genome replication and as a driver of dysregulated cell growth. In a previous study, we have identified LANA-interacting proteins using a protein array screen. Here, we explore the effect of LANA on the stability and activity of RLIM (RING finger LIM-domain-interacting protein, encoded by the RNF12 gene), a novel LANA-interacting protein identified in that protein screen. RLIM is an E3 ubiquitin ligase that leads to the ubiquitination and degradation of several transcription regulators, such as LMO2, LMO4, LHX2, LHX3, LDB1, and the telomeric protein TRF1. Expression of LANA leads to downregulation of RLIM protein levels. This LANA-mediated RLIM degradation is blocked in the presence of the proteasome inhibitor, MG132. Therefore, the interaction between LANA and RLIM could be detected in coimmunoprecipitation assay only in the presence of MG132 to prevent RLIM degradation. A RING finger mutant RLIM is resistant to LANA-mediated degradation, suggesting that LANA promotes RLIM autoubiquitination. Interestingly, we found that LANA enhanced the degradation of some RLIM substrates, such as LDB1 and LMO2, and prevented RLIM-mediated degradation of others, such as LHX3 and TRF1. We also show that transcription regulation by RLIM substrates is modulated by LANA. RLIM substrates are assembled into multiprotein transcription regulator complexes that regulate the expression of many cellular genes. Therefore, our study identified another way KSHV can modulate cellular gene expression.IMPORTANCE E3 ubiquitin ligases mark their substrates for degradation and therefore control the cellular abundance of their substrates. RLIM is an E3 ubiquitin ligase that leads to the ubiquitination and degradation of several transcription regulators, such as LMO2, LMO4, LHX2, LHX3, LDB1, and the telomeric protein TRF1. Here, we show that the Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded LANA protein enhances the ubiquitin ligase activity of RLIM, leading to enhanced RLIM autoubiquitination and degradation. Interestingly, LANA enhanced the degradation of some RLIM substrates, such as LDB1 and LMO2, and prevented RLIM-mediated degradation of others, such as LHX3 and TRF1. In agreement with protein stability of RLIM substrates, we found that LANA modulates transcription by LHX3-LDB1 complex and suggest additional ways LANA can modulate cellular gene expression. Our study adds another way a viral protein can regulate cellular protein stability, by enhancing the autoubiquitination and degradation of an E3 ubiquitin ligase.
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Watamoto Y, Futawaka K, Hayashi M, Matsushita M, Mitsutani M, Song Z, Koyama R, Fukuda Y, Nushida A, Nezu S, Kuwahara A, Kataoka K, Tagami T, Moriyama K. IGF-1 regulate the expression of uncoupling protein 2 via FOXO1. Growth Factors 2019; 37:247-256. [PMID: 32156173 DOI: 10.1080/08977194.2020.1739032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mitochondria uncoupling protein2 (UCP2) expressed ubiquitously is a key molecule of energy metabolism. Insulin-like growth factor-1 (IGF-1) is a hormone, a target molecule of growth hormone (GH) signal pathway, which is also known as the drug "mecasermin" for clinical usages. IGF-1 is seemed to be closely related to metabolic diseases, such as adult GH deficiency. However, there has not been reports depicted possible relationship with each other. So, we sought to elucidate the mechanisms by which expression of UCP2 is regulated by IGF-1 via FOXO1. The findings suggested that three sequences in the consensus UCP2 promoter play complementary functional roles in the functional expression of FOXO1. So, we found that FOXO1 is involved in IGF-1-mediated energy metabolism greater than that of direct action of GH via STAT5. Our findings suggested that IGF-1 was involved in energy metabolism by regulating the expression of UCP2 via the PI3K/Akt/FOXO1 pathway.
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Affiliation(s)
- Yukiko Watamoto
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Kumi Futawaka
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Misa Hayashi
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Midori Matsushita
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Mana Mitsutani
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Zilin Song
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Rie Koyama
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Yuki Fukuda
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Ayaka Nushida
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Syoko Nezu
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Akiko Kuwahara
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Kazusaburo Kataoka
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
| | - Tetsuya Tagami
- Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto, Japan
| | - Kenji Moriyama
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan
- Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto, Japan
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Watamoto Y, Futawaka K, Hayashi M, Matsushita M, Mitsutani M, Murakami K, Song Z, Koyama R, Fukuda Y, Nushida A, Nezu S, Kuwahara A, Kataoka K, Tagami T, Moriyama K. Insulin-like growth factor-1 directly mediates expression of mitochondrial uncoupling protein 3 via forkhead box O4. Growth Horm IGF Res 2019; 46-47:24-35. [PMID: 31158782 DOI: 10.1016/j.ghir.2019.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 03/26/2019] [Accepted: 05/21/2019] [Indexed: 01/01/2023]
Abstract
OBJECTIVE The objective of our study was to examine the direct action of insulin-like growth factor-1(IGF-1) signaling on energy homeostasis in myocytes. DESIGN We studied the IGF-1 stimulation of mitochondrial uncoupling protein 3 (UCP3) expression in the HEK 293 derived cell line TSA201, murine C2C12 skeletal muscle myoblasts, and rat L6 skeletal myoblasts. We also investigated the direct effect of IGF-1 on the Insulin/IGF-1 receptor (IGF-1R)/phosphatidylinositol 3 (PI3)-Akt/forkhead box O4 (FOXO4) pathway using a combination of a reporter assay, semi-quantitative polymerase chain reaction, western blotting, and animal experiments. RESULTS We demonstrated that IGF-1 regulates UCP3 expression via phosphorylation of FOXO4, which is a downstream signal transducer of IGF-1. UCP3 expression increased with activated FOXO4 in a dose-dependent manner. We also examined the functional FOXO4 binding site consensus sequences and identified it as the -1922 bp site in the UCP3 promoter region. UCP3 was also found to be concomitantly expressed with IGF-1 during differentiation of C2C12 myoblasts. Our animal experiments showed that high fat diet induced IGF-1 levels which likely influenced UCP3 expression in the skeletal muscle. CONCLUSION Our findings demonstrate that that IGF-1 directly stimulates UCP3 expression via the IGF-1/IGF-1R/PI3-Akt/FOXO4 pathway.
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Affiliation(s)
- Yukiko Watamoto
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Kumi Futawaka
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Misa Hayashi
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Midori Matsushita
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Mana Mitsutani
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Kana Murakami
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Zilin Song
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Rie Koyama
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Yuki Fukuda
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Ayaka Nushida
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Syoko Nezu
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Akiko Kuwahara
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Kazusaburo Kataoka
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Tetsuya Tagami
- Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
| | - Kenji Moriyama
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan; Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan.
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Matsushita M, Futawaka K, Hayashi M, Murakami K, Mitsutani M, Hatai M, Watamoto Y, Yoshikawa N, Nakamura K, Tagami T, Moriyama K. Cigarette Smoke Extract Modulates Functions of Peroxisome Proliferator-Activated Receptors. Biol Pharm Bull 2019; 42:1628-1636. [PMID: 31582651 DOI: 10.1248/bpb.b18-00991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cigarette smoke extract (CSE) contains many toxicants and may derange the physiological processes, such as cholesterol metabolism. We examined the impact of CSE on transcriptional regulation mediated peroxisome proliferator-activated receptors (PPARs) and its interaction with cofactors to elucidate differences in the molecular mechanism between CSE and other agonists of PPARs. We constructed several mutant PPARs (mPPARs) with amino acid substitution in the ligand-binding domain, which according to the molecular modeling, may affect the binding of agonists. In transient expression assays, each wild-type peroxisome proliferator-activated receptor (PPAR) mediated transcription stimulated by CSE was faintly yet significantly elevated compared to the control. The CSE-induced transcriptional activation was abolished in the H323A, H323Y, S342A, and H449A mPPARγs, although the activation elevated by pioglitazone was reserved. In the mPPARγ with Y473A and mPPARβ/δs with H286Y and Y436A, the pioglitazone-induced or L165041-activated transcriptional elevations were decreased and were lower than that of CSE-induced stimulation. These results suggested that CSE activated both mutant PPARs to be selectively different from those ligands. Mammalian two-hybrid assay illustrated that CSE could mildly recruit SRC1 or GRIP1 to the wild-type PPARγ. Representative ingredients, such as acrolein and crotonaldehyde present in CSE, could stimulate PPAR isoforms even at the toxicological concentrations and might possibly contribute to stimulatory effects. CSE mildly regulates the cholesterol metabolism-related genes, such as low density lipoprotein (LDL) receptor and Liver X receptor (LXR)β. In conclusion, these CSE effects the nuclear hormone receptors and their cofactors thereby disturbing metabolic phenomena. Therefore, CSE might be involved in cholesterol metabolism.
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Affiliation(s)
- Midori Matsushita
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Kumi Futawaka
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Misa Hayashi
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Kana Murakami
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Mana Mitsutani
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Mayuko Hatai
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Yukiko Watamoto
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Noriko Yoshikawa
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Kazuki Nakamura
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Tetsuya Tagami
- Division of Endocrinology, Metabolism and Hypertension, Clinical Research Institute, Kyoto Medical Center, National Hospital Organization
| | - Kenji Moriyama
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
- Division of Endocrinology, Metabolism and Hypertension, Clinical Research Institute, Kyoto Medical Center, National Hospital Organization
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7
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Hayashi M, Futawaka K, Matsushita M, Koyama R, Fun Y, Fukuda Y, Nushida A, Nezu S, Tagami T, Moriyama K. GH directly stimulates UCP3 expression. Growth Horm IGF Res 2018; 40:44-54. [PMID: 29398371 DOI: 10.1016/j.ghir.2018.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 12/27/2017] [Accepted: 01/18/2018] [Indexed: 01/23/2023]
Abstract
OBJECTIVE We evaluated the direct action of GH signaling in energy homeostasis in myocytes. DESIGN We investigated the GH-induced expression of UCP3 in human embryonic kidney 293 cells, human H-EMC-SS chondrosarcoma cells, murine C2C12 skeletal muscle myoblasts, and rat L6 skeletal muscle cells, as well as its direct effect on the GHR/JAK/STAT5 pathway using a combination of a reporter assay, real-time quantitative polymerase chain reaction, and western blotting. RESULTS We demonstrated that the regulation of energy metabolism by GH involves UCP3 via activated STAT5, a signal transducer downstream of GH. UCP3 expression increased with STAT5 in a dose-dependent manner and was higher than that of UCP2. We confirmed the functional STAT5 binding site consensus sequences at -861 and -507 bp in the UCP3 promoter region. CONCLUSION The results suggest that GH stimulates UCP3 directly and that UCP2 and that UCP3 participate in the signal transduction pathway that functions downstream of the GHR/JAK/STAT.
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Affiliation(s)
- Misa Hayashi
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Kumi Futawaka
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Midori Matsushita
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Rie Koyama
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Yue Fun
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Yuki Fukuda
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Ayaka Nushida
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Syoko Nezu
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Tetsuya Tagami
- Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
| | - Kenji Moriyama
- Medicine & Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan; Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan.
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8
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Hayashi M, Futawaka K, Matsushita M, Hatai M, Yoshikawa N, Nakamura K, Tagami T, Moriyama K. Cigarette Smoke Extract Disrupts Transcriptional Activities Mediated by Thyroid Hormones and Its Receptors. Biol Pharm Bull 2018; 41:383-393. [PMID: 29491215 DOI: 10.1248/bpb.b17-00735] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cigarette smoke contains over 4800 compounds, including at least 200 toxicants or endocrine disruptors. Currently, effects of cigarette smoke on thyroid hormone (TH) levels remains to be clarified. Here, we demonstrate that cigarette smoke extract (CSE) possesses thyroid hormone properties and acts synergistically as a partial agonist for thyroid hormone receptors (TRs) in the presence of TH. In transient gene expression experiments, CSE stimulated transcriptional activity with TH in a dose-dependent manner. Stimulatory effects were observed with physiological TH concentrations, although CSE did not activate TRs without TH. CSE (5%) dissolved in phosphate-buffered saline (PBS) supplemented with 1 nM TH was approximately comparable to 3.2±0.1 and 2.3±0.2 nM of TRα1 and TRβ1, respectively. To illustrate probable mechanisms of the CSE agonistic activity, effects on TR mediated transcriptional functions with cofactors were investigated. With a mammalian two-hybrid assay, CSE recruited the nuclear coactivators glucocorticoid receptor interacting protein 1 (GRIP1) and steroid receptor coactivator 1 (SRC1) to the TR. Unsaturated carbonyl compounds, acrolein, crotonaldehyde, and methyl vinyl ketone, representative constituents of CSE, retained such agonistic properties and possibly contributed to stimulatory effects. The results suggest that CSE recruits a transcriptional activator and may reinforce TH binding to the TR additively, resulting in gene expression. CSE partially agonizes TH action and may disturb the function of various nuclear hormone receptor types and their cofactors to disrupt the physiological processes.
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Affiliation(s)
- Misa Hayashi
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Kumi Futawaka
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Midori Matsushita
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Mayuko Hatai
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Noriko Yoshikawa
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Kazuki Nakamura
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
| | - Tetsuya Tagami
- Division of Endocrinology, Metabolism and Hypertension, Clinical Research Institute, Kyoto Medical Center, National Hospital Organization
| | - Kenji Moriyama
- Department of Medicine and Clinical Science, Graduate School of Pharmaceutical Sciences, Mukogawa Women's University
- Division of Endocrinology, Metabolism and Hypertension, Clinical Research Institute, Kyoto Medical Center, National Hospital Organization
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9
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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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10
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Sasaki S, Matsushita A, Kuroda G, Nakamura HM, Oki Y, Suda T. The Mechanism of Negative Transcriptional Regulation by Thyroid Hormone: Lessons From the Thyrotropin β Subunit Gene. VITAMINS AND HORMONES 2017; 106:97-127. [PMID: 29407449 DOI: 10.1016/bs.vh.2017.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Thyroid hormone (T3) activates (positive regulation) or represses (negative regulation) target genes at the transcriptional level. The molecular mechanism of the former has been elucidated in detail; however, the mechanism for negative regulation has not been established. The best example of the gene that is negatively regulated by T3 is the thyrotropin (thyroid-stimulating hormone) β subunit (TSHβ) gene. Analogous to the T3-responsive element (TRE) in positive regulation, a negative TRE (nTRE) has been postulated in the TSHβ gene. However, TSHβ promoter analysis, performed in the presence of transcription factors Pit1 and GATA2, which are determinants of thyrotroph differentiation in the pituitary, revealed that the nTRE is dispensable for inhibition by T3. We propose a tethering model in which the T3 receptor is tethered to GATA2 via protein-protein interaction and inhibits GATA2-dependent transactivation of the TSHβ gene in a T3-dependent manner.
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Affiliation(s)
| | | | - Go Kuroda
- Hamamatsu University School of Medicine, Shizuoka, Japan
| | | | - Yutaka Oki
- Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Takafumi Suda
- Hamamatsu University School of Medicine, Shizuoka, Japan
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Figliozzi RW, Chen F, Hsia SV. New insights on thyroid hormone mediated regulation of herpesvirus infections. Cell Biosci 2017; 7:13. [PMID: 28344765 PMCID: PMC5360088 DOI: 10.1186/s13578-017-0140-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Accepted: 03/14/2017] [Indexed: 12/22/2022] Open
Abstract
Thyroid hormone (T3) has been suggested to participate in the regulation of herpesvirus replication during reactivation. Clinical observations and in vivo experiments suggest that T3 are involved in the suppression of herpes virus replication. In vitro, differentiated LNCaP cells, a human neuron-like cells, further resisted HSV-1 replication upon addition of T3. Previous studies indicate that T3 controlled the expression of several key viral genes via its nuclear receptors in differentiated LNCaP cells. Additional observation showed that differentiated LNCaP cells have active PI3K signaling and inhibitor LY294002 can reverse T3-mediated repression of viral replication. Active PI3K signaling has been linked to HSV-1 latency in neurons. The hypothesis is that, in addition to repressing viral gene transcription at the nuclear level, T3 may influence PI3K signaling to control HSV-1 replication in human neuron-like cells. We review the genomic and non-genomic regulatory roles of T3 by examining the phosphoinositide 3-kinase (PI3K) pathway gene expression profile changes in differentiated LNCaP cells under the influence of hormone. The results indicated that 15 genes were down-regulated and 22 genes were up-regulated in T3-treated differentiated LNCaP cells in comparison to undifferentiated state. Of all these genes, casein kinase 2 (CK2), a key component to enhance PI3K signaling pathway, was significantly increased upon T3 treatment only while the cells were differentiated. Further studies revealed that CK2 inhibitors tetrabrominated cinnamic acid (TBCA) and 4, 5, 6, 7-tetrabromo-2H-benzotriazole (TBB) both reversed the T3-mediated repression of viral replication. Together these observations suggested a new approach to understanding the roles of T3 in the complicated regulation of HSV-1 replication during latency and reactivation.
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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, USA.,Department of Natural Sciences, School of Agriculture and Natural Sciences, University of Maryland Eastern Shore, Princess Anne, USA
| | - Feng Chen
- Department of Pharmaceutical Sciences, School of Pharmacy and Health Professions, University of Maryland Eastern Shore, Princess Anne, USA
| | - S Victor Hsia
- Department of Pharmaceutical Sciences, School of Pharmacy and Health Professions, University of Maryland Eastern Shore, Princess Anne, USA.,Department of Natural Sciences, School of Agriculture and Natural Sciences, University of Maryland Eastern Shore, Princess Anne, USA
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Futawaka K, Tagami T, Fukuda Y, Koyama R, Nushida A, Nezu S, Imamoto M, Kasahara M, Moriyama K. Growth hormone regulates the expression of UCP2 in myocytes. Growth Horm IGF Res 2016; 29:57-62. [PMID: 27150070 DOI: 10.1016/j.ghir.2016.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Revised: 03/03/2016] [Accepted: 04/10/2016] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To determine if and how growth hormone (GH) signaling is involved in energy metabolism. DESIGN We used human embryonic kidney TSA201 cells, human H-EMC-SS chondrosarcoma cells, rat L6 skeletal muscle cells, and murine C2C12 skeletal muscle myoblasts to investigate GH-induced expression of uncoupling protein2 (UCP2) to the GHR/JAK/STAT5 pathway by a combination of a reporter assay, electrophoretic mobility shift assay (EMSA), real-time quantitative PCR, Western blotting. RESULTS We demonstrated that the regulation energy metabolism, which was hypothesized to be directly acted on by GH, involves UCP2 via activated STAT5B, a signal transducer downstream of GH. We also showed that the sequence at the -586 'TTCnGA' may function as a novel putative consensus sequence of STAT5s. CONCLUSION The results suggest that GH regulates energy metabolism directly in myocytes and that UCP2 participates in the signal transduction pathway that functions downstream of the GHR/JAK/STAT.
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Affiliation(s)
- Kumi Futawaka
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan.
| | - Tetsuya Tagami
- Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
| | - Yuki Fukuda
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Rie Koyama
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Ayaka Nushida
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Syoko Nezu
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan
| | - Miyuki Imamoto
- Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
| | - Masato Kasahara
- Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
| | - Kenji Moriyama
- Medicine and Clinical Science, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo 663-8179, Japan; Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan; Department of Nephrology and Blood Purification, Institute of Biomedical Research and Innovation, Kobe Medical Frontier Center, Kobe 650-0047, Japan
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13
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Futawaka K, Tagami T, Fukuda Y, Koyama R, Nushida A, Nezu S, Yamamoto H, Imamoto M, Kasahara M, Moriyama K. Transcriptional activation of the wild-type and mutant vitamin D receptors by vitamin D3 analogs. J Mol Endocrinol 2016; 57:23-32. [PMID: 27154546 DOI: 10.1530/jme-16-0048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/06/2016] [Indexed: 11/08/2022]
Abstract
The active form of vitamin D3 (1α,25(OH)2D3, also known as calcitriol) controls the expression of target genes via the vitamin D receptor (VDR). Vitamin D-dependent rickets type II (VDDRII) is a congenital disease caused by inactivating mutations in the VDR The condition is treated with high doses of calcitriol, but the therapeutic effects of other synthetic VD3 analogs have not yet been investigated. In the present study, we analyzed the transcriptional activity of seven different VD3 analogs with VDRs carrying ligand-binding domain mutations identified in VDDRII patients. Wild-type VDR (WT-VDR) and seven mutant VDRs were expressed in TSA201 human embryonic kidney cells, HepG2 human liver cancer cells, and MC3T3-E1 mouse calvaria cells, and their transcriptional activation with VD3 analogs were analyzed by performing transient expression assays, western blotting, and quantitative real-time PCR. The results demonstrated that falecalcitriol stimulated significantly higher transcriptional activation of the WT-VDR and some mutant VDRs than did calcitriol. Calcitriol showed almost no transcriptional activation of the VDR with the I268T mutation identified in a severe case of VDDRII, whereas falecalcitriol caused a dose-dependent increase in the activation of this mutant VDR. Our findings demonstrate that falecalcitriol has a VDR activation profile distinct from that of calcitriol and may exhibit therapeutic effects even on difficult-to-treat VDDRII cases resistant to calcitriol. It is also possible that VDDRII patients responding to high doses of calcitriol could be appropriately treated with low doses of falecalcitriol.
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Affiliation(s)
- Kumi Futawaka
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Tetsuya Tagami
- Clinical Research Institute for Endocrine and Metabolic DiseasesNational Hospital Organization Kyoto Medical Center, Kyoto, Japan
| | - Yuki Fukuda
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Rie Koyama
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Ayaka Nushida
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Shoko Nezu
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan
| | - Hironori Yamamoto
- Department of Health and NutritionFaculty of Human Life, Jin-ai University, Fukui, Japan
| | - Miyuki Imamoto
- Department of Nephrology and Blood PurificationInstitute of Biomedical Research and Innovation, Kobe Medical Frontier Center, Kobe, Japan
| | - Masato Kasahara
- Department of Nephrology and Blood PurificationInstitute of Biomedical Research and Innovation, Kobe Medical Frontier Center, Kobe, Japan
| | - Kenji Moriyama
- Department of Medicine and Clinical ScienceFaculty of Pharmaceutical Sciences, Mukogawa Women's University, Hyogo, Japan Clinical Research Institute for Endocrine and Metabolic DiseasesNational Hospital Organization Kyoto Medical Center, Kyoto, Japan Department of Nephrology and Blood PurificationInstitute of Biomedical Research and Innovation, Kobe Medical Frontier Center, Kobe, Japan
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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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15
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Ohno M, Fujita M, Nishizuka M, Osada S, Imagawa M. Interactions of Thyroid Hormone Receptor with Ku Proteins and Interleukin Enhancer Binding Factor 3 Modulate the Promoter Activity of Thyroid-Stimulating Hormone Alpha. Biol Pharm Bull 2012; 35:380-4. [DOI: 10.1248/bpb.35.380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Masae Ohno
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Mayu Fujita
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Makoto Nishizuka
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Shigehiro Osada
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
| | - Masayoshi Imagawa
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Nagoya City University
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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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18
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Tagami T, Usui T, Shimatsu A, Beniko M, Yamamoto H, Moriyama K, Naruse M. Aberrant expression of thyroid hormone receptor beta isoform may cause inappropriate secretion of TSH in a TSH-secreting pituitary adenoma. J Clin Endocrinol Metab 2011; 96:E948-52. [PMID: 21430027 DOI: 10.1210/jc.2010-2496] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Patients with TSH-secreting pituitary adenomas (TSHoma) show inappropriate secretion of TSH; serum TSH levels are not suppressed despite high serum free thyroid hormone levels. The mechanism of a defect in negative regulation of TSH in a TSHoma is still unclear. OBJECTIVE Recently, we cloned a novel thyroid hormone receptor β isoform (TRβ4) from a human pituitary library. To elucidate the clinical significance of TRβ4, we investigated the expression of this isoform in TSHoma. METHODS RT-PCR was performed to detect TRβ isoforms such as TRβ1, TRβ2, and TRβ4 using RNA obtained from surgically resected TSHoma. The effects of TRβ4 on the TSH gene expression were examined in the transient gene expression experiments. RESULTS Quantitative analysis using a real-time PCR revealed that relative expression of TRβ4 to TRβ1+2 was higher in three TSHoma than in a prolactinoma or a nonfunctioning pituitary adenoma. TRβ4 construct did not mediate T(3)-dependent gene regulation but inhibited the negative regulation of TSHα mediated by TRβ1 or TRβ2. CONCLUSIONS Aberrant expression of TRβ4 may partly contribute to the inappropriate secretion of TSH in a TSHoma.
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Affiliation(s)
- Tetsuya Tagami
- Division of Endocrinology and Metabolism, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Mukaihata-cho 1-1, Fukakusa, Fushimi-ku, Kyoto 612-8555, Japan.
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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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20
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Liu YY, Nakatani T, Kogai T, Mody K, Brent GA. Thyroid hormone and COUP-TF1 regulate kallikrein-binding protein (KBP) gene expression. Endocrinology 2011; 152:1143-53. [PMID: 21266512 PMCID: PMC3040047 DOI: 10.1210/en.2010-0580] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Kallikrein-binding protein (KBP) is a component of the kallikrein-kinin system that mediates vasodilation and inhibits tumor growth by antagonizing vascular endothelial growth factor-mediated angiogenesis. We demonstrate that KBP gene expression is repressed by T(3) and modulated by the orphan nuclear receptor, chicken ovalbumin upstream promoter transcription factor 1 (COUP-TF1). In hypothyroid mice, KBP mRNA expression in the testis was increased 2.1-fold compared with euthyroid mice. We have identified two negative thyroid hormone response elements (nTREs) in the mouse KBP gene, nTRE1 located in the 5' flanking region (-53 to -29) and nTRE2, located in the first intron (104-132). We used functional assays, cofactor knockdown, and chromatin immunoprecipitation assays to characterize nTRE1 and nTRE2 in hepatic (HepG2) and testes (GC-1spg) cell lines. Reporter expression directed by both elements was enhanced with addition of thyroid hormone receptor and repressed with the addition of T(3). COUP-TF1 enhanced basal expression of both elements but blunted unliganded thyroid hormone receptor enhancement and T(3) repression of nTRE1 but not nTRE2. Both nTREs bound nuclear corepressor and binding increased in response to T(3). Nuclear corepressor knockdown resulted in loss of T(3) repression of both nTRE1 and nTRE2. COUP-TF1, which usually represses T(3) induction of positive thyroid hormone response elements, reverses T(3) repression mediated by nTRE1 in the mouse KBP gene. Endogenous KBP expression is repressed by T(3) and two functional nTREs, both of which are required, have been characterized in the KBP gene. COUP-TF1 may be an important factor to modulate expression of genes that are repressed by T(3).
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Affiliation(s)
- Yan-Yun Liu
- Molecular Endocrinology Laboratory, Building 114, Room 230, Veterans Affairs Greater Los Angeles Healthcare System, 11301 Wilshire Boulevard, Los Angeles, California 90073, USA
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Haddad F, Jiang W, Bodell PW, Qin AX, Baldwin KM. Cardiac myosin heavy chain gene regulation by thyroid hormone involves altered histone modifications. Am J Physiol Heart Circ Physiol 2010; 299:H1968-80. [PMID: 20833952 DOI: 10.1152/ajpheart.00644.2010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The antithetical regulation of cardiac α- and β-myosin heavy chain (MHC) genes by thyroid hormone (T(3)) is not well understood but appears to involve thyroid hormone interaction with its nuclear receptor and MHC promoters as well as cis-acting noncoding regulatory RNA (ncRNA). Both of these phenomena involve epigenetic regulations. This study investigated the extent that altered thyroid state induces histone modifications in the chromatin associated with the cardiac MHC genes. We hypothesized that specific epigenetic events could be identified and linked to cardiac MHC gene switching in response to a hypothyroid or hyperthyroid state. A hypothyroid state was induced in rats by propylthiouracil treatment (PTU), whereas a hyperthyroid (T(3)) was induced by T(3) treatment. The left ventricle was analyzed after 7 days for MHC pre-mRNA expression, and the chromatin was assessed for enrichment in specific histone modifications using chromatin immunoprecipitation quantitative PCR assays. At both the α-MHC promoter and the intergenic region, the enrichment in acetyl histone H3 at K9/14 (H3K9/14ac) and trimethyl histone H3 at K4 (H3K4me3) changed in a similar fashion. They were both decreased with PTU treatment but did not change under T(3), except at a location situated 5' to the antisense intergenic transcription start site. These same marks varied differently on the β-MHC promoter. For example, H3K4me3 enrichment correlated with the β-promoter activity in PTU and T(3) groups, whereas H3K9/14ac was repressed in the T(3) group but did not change under PTU. Histone H3K9me was enriched in chromatin of both the intergenic and α-MHC promoters in the PTU group, whereas histone H4K20me1 was enriched in chromatin of β-MHC promoter in the normal control and T(3) groups. Collectively, these findings provide evidence that specific epigenetic phenomena modulate MHC gene expression in altered thyroid states.
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Affiliation(s)
- F Haddad
- Department of Physiology and Biophysics, University of California, Irvine, California 92697-4560, USA.
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Wang D, Xia X, Weiss RE, Refetoff S, Yen PM. Distinct and histone-specific modifications mediate positive versus negative transcriptional regulation of TSHalpha promoter. PLoS One 2010; 5:e9853. [PMID: 20352046 PMCID: PMC2844428 DOI: 10.1371/journal.pone.0009853] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 02/03/2010] [Indexed: 11/19/2022] Open
Abstract
Background Hormonally-regulated histone modifications that govern positive versus negative transcription of target genes are poorly characterized despite their importance for normal and pathological endocrine function. There have been only a few studies examining chromatin modifications on target gene promoters by nuclear hormone receptors. Moreover, these studies have focused on positively-regulated target genes. TSHα, a heterodimer partner for thyrotropin (TSH), is secreted by the pituitary gland. T3 negatively regulates TSHα gene expression via thyroid hormone receptors (TRs) which belong to the nuclear hormone receptor superfamily, whereas thyrotropin releasing hormone (TRH) positively regulates via the TRH receptor, a G protein-coupled receptor. Methodology/Principal Findings We studied regulation of the TSHα gene by cAMP and T3 using chromatin immunoprecipitation (ChIP) assays in stably-transfected rat pituitary cells containing the human TSHα promoter. Interestingly, cAMP selectively increased histone H4 acetylation whereas, as previously reported, T3 induced histone H3 acetylation. In particular, cAMP increased H4K5 and H4K8 acetylation and decreased H4K20 trimethylation, modifications associated with transcriptional activation. T3 increased H3K9 and H3K18 acetylation and H3K4 trimethylation; however, it also decreased H3K27 acetylation and increased H3K27 trimethylation which are associated with transcriptional repression. Of note, cAMP recruited pCREB, CBP/p300, and PCAF to the promoter whereas T3 caused dissociation of NCoR/SMRT and HDAC3. Overexpression of a dominant negative mutant thyroid hormone receptor (TR) from a patient with resistance to thyroid hormone (RTH) led to less T3-dependent negative regulation and partially blocked histone H3 modifications of the TSHα promoter. Conclusions/Significance Our findings show that non-overlapping and specific histone modifications determine positive versus negative transcriptional regulation, and integrate opposing hormonal and intracellular signals at the TSHα promoter. A mutant TR from a patient with RTH exerted dominant negative activity by blocking the histone modifications induced by T3 on the TSHα promoter and likely contributes to the inappropriate TSH production observed in RTH.
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Affiliation(s)
- Dongqing Wang
- Endocrinology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | | | - Roy E. Weiss
- Departments of Medicine and Pediatrics, University of Chicago, Chicago, Illinois, United States of America
| | - Samuel Refetoff
- Departments of Medicine and Pediatrics, University of Chicago, Chicago, Illinois, United States of America
| | - Paul M. Yen
- Endocrinology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disease Program, Duke-National University of Singapore Graduate Medical School, Singapore, Singapore
- * E-mail:
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Sugrue ML, Vella KR, Morales C, Lopez ME, Hollenberg AN. The thyrotropin-releasing hormone gene is regulated by thyroid hormone at the level of transcription in vivo. Endocrinology 2010; 151:793-801. [PMID: 20032051 PMCID: PMC2817611 DOI: 10.1210/en.2009-0976] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The expression of the TRH gene in the paraventricular nucleus (PVH) of the hypothalamus is required for the normal production of thyroid hormone (TH) in rodents and humans. In addition, the regulation of TRH mRNA expression by TH, specifically in the PVH, ensures tight control of the set point of the hypothalamic-pituitary-thyroid axis. Although many studies have assumed that the regulation of TRH expression by TH is at the level of transcription, there is little data available to demonstrate this. We used two in vivo model systems to show this. In the first model system, we developed an in situ hybridization (ISH) assay directed against TRH heteronuclear RNA to measure TRH transcription directly in vivo. We show that in the euthyroid state, TRH transcription is present both in the PVH and anterior/lateral hypothalamus. In the hypothyroid state, transcription is activated in the PVH only and can be shut off within 5 h by TH. In the second model system, we employed transgenic mice that express the Cre recombinase under the control of the genomic region containing the TRH gene. Remarkably, TH regulates Cre expression in these mice in the PVH only. Taken together, these data affirm that TH regulates TRH at the level of transcription in the PVH only and that genomic elements surrounding the TRH gene mediate its regulation by T(3). Thus, it should be possible to identify the elements within the TRH locus that mediate its regulation by T(3) using in vivo approaches.
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Affiliation(s)
- Michelle L Sugrue
- Division of Endocrinology, Metabolism, and Diabetes, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, E/CLS-0738, Boston, Massachusetts 02215, USA
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24
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Sánchez-Pacheco A, Martínez-Iglesias O, Méndez-Pertuz M, Aranda A. Residues K128, 132, and 134 in the thyroid hormone receptor-alpha are essential for receptor acetylation and activity. Endocrinology 2009; 150:5143-52. [PMID: 19819978 DOI: 10.1210/en.2009-0117] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The thyroid hormone receptor (TR)-alpha is a nuclear receptor that mediates both transrepression and ligand-dependent transactivation. Here we show that TRalpha is posttranslationally modified by acetylation in response to its own ligand (T(3)). Acetylation increases binding to DNA. Using mutagenesis, we identified three conserved lysine residues in the carboxi-terminal extension (CTE) of the DNA binding domain that are targets of the cAMP-response element-binding protein acetyltransferase. Substitution of these lysines by arginines in TRalpha decreased ligand binding affinity and precluded ligand-dependent release of corepressors and recruitment of coactivators. The acetylation TRalpha mutant lost the ability to transactivate even at high T(3) concentrations and acts as a dominant-negative inhibitor of wild-type TR activity. In addition, whereas native TRalpha interferes with AP-1 function, the mutant is unable to mediate transrepression. Finally, TRalpha suppresses NIH-3T3 fibroblast transformation by the Ras oncogene both in a ligand-dependent and -independent manner, but the CTE mutant is unable to mediate ligand-dependent repression of transformation. These results reveal a key role for the CTE region on acetylation, ligand affinity, transactivation, transrepression, and antitransforming properties of TRalpha.
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Affiliation(s)
- Aurora Sánchez-Pacheco
- Instituto de Investigaciones Biomédicas A. Sols, C/Arturo Duperier, 4 28029 Madrid, Spain.
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25
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Alonso M, Goodwin C, Liao X, Ortiga-Carvalho T, Machado DS, Wondisford FE, Refetoff S, Weiss RE. In vivo interaction of steroid receptor coactivator (SRC)-1 and the activation function-2 domain of the thyroid hormone receptor (TR) beta in TRbeta E457A knock-in and SRC-1 knockout mice. Endocrinology 2009; 150:3927-34. [PMID: 19406944 PMCID: PMC2717870 DOI: 10.1210/en.2009-0093] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The activation function-2 (AF-2) domain of the thyroid hormone (TH) receptor (TR)-beta is a TH-dependent binding site for nuclear coactivators (NCoA), which modulate TH-dependent gene transcription. In contrast, the putative AF-1 domain is a TH-independent region interacting with NCoA. We determined the specificity of the AF-2 domain and NCoA interaction by evaluating thyroid function in mice with combined disruption of the AF-2 domain in TRbeta, due to a point mutation (E457A), and deletion of one of the NCoAs, steroid receptor coactivator (SRC)-1. The E457A mutation was chosen because it abolishes NCoA recruitment in vitro while preserving normal TH binding and corepressor interactions resulting in resistance to TH. At baseline, disruption of SRC-1 in the homozygous knock-in (TRbeta(E457A/E457A)) mice worsened the degree of resistance to TH, resulting in increased serum T(4) and TSH. During TH deprivation, disruption of AF-2 and SRC-1 resulted in a TSH rise 50% of what was seen when AF-2 alone was removed, suggesting that SRC-1 was interacting outside of the AF-2 domain. Therefore, 1) during TH deprivation, SRC-1 is necessary for activating the hypothalamic-pituitary-thyroid axis; 2) ligand-dependent repression of TSH requires an intact AF-2; and 3) SRC-1 may interact with the another region of the TRbeta or the TRalpha to regulate TH action in the pituitary. This report demonstrates the dual interaction of NCoA in vivo: the TH-independent up-regulation possibly through another domain and TH-dependent down-regulation through the AF-2 domain.
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Affiliation(s)
- Manuela Alonso
- Department of Medicine, Committees on Genetics, The University of Chicago, Chicago, Illinois 60637, USA
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26
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Wang D, Xia X, Liu Y, Oetting A, Walker RL, Zhu Y, Meltzer P, Cole PA, Shi YB, Yen PM. Negative regulation of TSHalpha target gene by thyroid hormone involves histone acetylation and corepressor complex dissociation. Mol Endocrinol 2009; 23:600-9. [PMID: 19196836 DOI: 10.1210/me.2008-0389] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Currently, little is known about histone modifications and molecular mechanisms of negatively regulated transcription. In pituitary cells, thyroid hormone (T(3)) decreased transcription, and surprisingly increased histone acetylation, of TSHalpha promoter. This increase was mediated directly by thyroid hormone receptor. Histone acetylation of H3K9 and H3K18 sites, two modifications usually associated with transcriptional activation, occur in negative regulation of TSHalpha promoter. T(3) also caused release of a corepressor complex composed of histone deacetylase 3 (HDAC3), transducin beta-like protein 1, and nuclear receptor coprepressor (NCoR)/ silencing mediator for retinoic and thyroid hormone receptor from TSHalpha promoter in chromatin immunoprecipitation assays. NCoR and HDAC3 overexpression selectively increased ligand-independent basal transcription. Two histone acetyltransferase inhibitors increased overall transcription but did not abrogate negative regulation or NCoR/HDAC3 complex release by T(3). Chromatin immunoprecipitation analyses of an endogenous positively regulated target gene showed increased histone acetylation and corepressor complex release with T(3) treatment. Finally, microarray analyses suggested there is a subset of negatively regulated genes with increased histone acetylation. These findings demonstrate the critical role of NCoR/HDAC3 complex in negative regulation of TSHalpha gene expression and show that similar complexes and overlapping epigenetic modifications can participate in both negative and positive transcriptional regulation.
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Affiliation(s)
- Dongqing Wang
- Endocrinology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA
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Tagami T, Yamamoto H, Moriyama K, Sawai K, Usui T, Shimatsu A, Naruse M. A selective peroxisome proliferator-activated receptor-gamma modulator, telmisartan, binds to the receptor in a different fashion from thiazolidinediones. Endocrinology 2009; 150:862-70. [PMID: 19147680 DOI: 10.1210/en.2008-0502] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Angiotensin type 1 receptor blockers are widely used for the treatment of hypertension, and one angiotensin type 1 receptor blocker, telmisartan, specifically activates the peroxisome proliferator-activated receptor (PPAR)-gamma. We studied the impact of PPARgamma mutants on transcriptional control and interaction with cofactors to elucidate differences in the molecular mechanism between telmisartan and other PPARgamma agonists, thiazolidinediones (TZDs). We created several amino acid substitutions in the ligand binding domain of PPARgamma that, based on molecular modeling, may affect the binding of these agents. In transient expression experiments, wild-type PPARgamma-mediated transcription stimulated by telmisartan was more than one third of that stimulated by TZDs. The activation stimulated by TZDs was impaired, whereas activation stimulated by telmisartan was retained, in the H323Y, S342A, and H449A mutants. In the Y473A mutant, the TZD-induced activation was further impaired and lower than that of telmisartan-induced activation. Coexpression of coactivators enhanced the activation by both telmisartan and TZDs, but activation by telmisartan always exceeded that of TZDs in the Y473A mutant. Based on a mammalian two-hybrid assay, the interaction with corepressors was retained in Y473A. Telmisartan and TZDs, but not 9cis retinoic acid, dissociated corepressors from the wild-type PPARgamma. Telmisartan most effectively dissociated corepressors from Y473A. The interaction with coactivators was enhanced by TZD activation of wild-type PPARgamma and both telmisartan and TZD activation of Y473A. Thus, the Y473A mutant is selectively stimulated by telmisartan but not TZDs, suggesting that telmisartan and TZDs have differential effects on the transcriptional control. In conclusion, these PPARgamma mutants could be powerful tools for developing novel therapeutic agents that retain the metabolic efficacy of PPARgamma activation with fewer adverse effects, such as the increase in body weight associated with TZDs.
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Affiliation(s)
- Tetsuya Tagami
- Clinical Research Institute, Kyoto Medical Center, National Hospital Organization, Fukakusa, Kyoto, Japan.
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28
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The nuclear corepressor, NCoR, regulates thyroid hormone action in vivo. Proc Natl Acad Sci U S A 2008; 105:19544-9. [PMID: 19052228 DOI: 10.1073/pnas.0804604105] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The thyroid hormone receptor (TR) has been proposed to regulate expression of target genes in the absence of triiodothyronine (T(3)) through the recruitment of the corepressors, NCoR and SMRT. Thus, NCoR and SMRT may play an essential role in thyroid hormone action, although this has never been tested in vivo. To accomplish this, we developed mice that express in the liver a mutant NCoR protein (L-NCoRDeltaID) that cannot interact with the TR. L-NCoRDeltaID mice appear grossly normal, however, when made hypothyroid the repression of many positively regulated T(3)-target genes is abrogated, demonstrating that NCoR plays a specific and sufficient role in repression by TR in the absence of T(3). Remarkably, in the euthyroid state, expression of many T(3)-targets is also up-regulated in L-NCoRDeltaID mice, demonstrating that NCoR also determines the magnitude of the response to T(3) in euthyroid animals. Although positive T(3) targets were up-regulated in L-NCoRDeltaID mice in the hypo- and euthyroid state, there was little effect seen on negatively regulated T(3) target genes. Thus, NCoR is a specific regulator of T(3)-action in vivo and mediates repression by the unliganded TR in hypothyroidism. Furthermore, NCoR appears to play a key role in determining the tissue-specific responses to similar levels of circulating T(3). Interestingly, NCoR recruitment to LXR is also impaired in this model, leading to activation of LXR-target genes, further demonstrating that NCoR recruitment regulates multiple nuclear receptor signaling pathways.
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29
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Weinhofer I, Kunze M, Rampler H, Forss-Petter S, Samarut J, Plateroti M, Berger J. Distinct modulatory roles for thyroid hormone receptors TRα and TRβ in SREBP1-activated ABCD2 expression. Eur J Cell Biol 2008; 87:933-45. [DOI: 10.1016/j.ejcb.2008.08.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 08/18/2008] [Accepted: 08/20/2008] [Indexed: 01/23/2023] Open
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Weitzel JM. To bind or not to bind - how to down-regulate target genes by liganded thyroid hormone receptor? Thyroid Res 2008; 1:4. [PMID: 19014660 PMCID: PMC2583983 DOI: 10.1186/1756-6614-1-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 10/11/2008] [Indexed: 01/16/2023] Open
Abstract
The terrain is well explored regarding genes whose gene expression is up-regulated upon binding of thyroid hormone (TH) to its nuclear receptor. This regulation mechanism has been intensively studied and is well understood. In contrast, a lot of white spots remain on the map when it comes to target genes whose expression is down-regulated upon binding of TH to the thyroid hormone receptor (TR). Since no consistent mechanism has been proposed to explain ligand-dependent down-regulation of target gene transcription several working hypotheses favour different molecular mechanisms. Some working theories suggest a direct binding of TR to regulatory elements of target genes. Others favour models that are independent of a direct DNA binding event. However recent data suggested that a direct binding of TR to DNA is dispensable for TH-dependent negative gene transcription.
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Affiliation(s)
- Joachim M Weitzel
- Institute of Experimental Endocrinology, Charité University Medicine Berlin, 13353 Berlin, Germany.
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31
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Danzi S, Klein S, Klein I. Differential regulation of the myosin heavy chain genes alpha and beta in rat atria and ventricles: role of antisense RNA. Thyroid 2008; 18:761-8. [PMID: 18631005 PMCID: PMC2879492 DOI: 10.1089/thy.2008.0043] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND The myosin heavy chain (MHC) genes are regulated by triiodothyronine (T3) in a reciprocal and chamber-specific manner. To further our understanding of the potential mechanisms involved, we determined the T3 responsiveness of the MHC genes, alpha and beta, and the beta-MHC antisense (AS) gene in the rat ventricles and atria. METHODS Hypothyroid rats were administered a single physiologic (1 microg) or pharmacologic (20 microg) dose of T3, and sequential measurements of beta-MHC hn- and AS RNA and alpha-MHC heterogeneous nuclear RNA from rat ventricular and atrial myocardium were performed with reverse transcription PCR. RESULTS We have demonstrated that T3 treatment increases the myocyte content of an AS beta-MHC RNA in atria and ventricles that includes sequences complementary to both the first 5' and last 3' introns of the beta-MHC sense transcript. In the hypothyroid rat ventricle, beta-MHC sense RNA expression is maximal, while in the euthyroid rat ventricle, beta-MHC AS RNA is maximal. beta-MHC AS expression increased by 52 +/- 9.8% at the peak, 24 hours after injection of a physiologic dose of T3 (1 microg/animal), while beta-MHC sense RNA decreased by 41 +/- 2.2% at 36 hours, the nadir. In hypothyroid atria, beta-MHC AS RNA was induced by threefold within 6 hours of administration of 1 microg T3, demonstrating that in the atria, beta-MHC AS expression is regulated by T3, while alpha-MHC expression is not. CONCLUSIONS In the hypothyroid rat heart ventricle, beta-MHC AS RNA expression increases in response to T3 similar to that of alpha-MHC. Simultaneous measures of beta-MHC sense RNA are decreased, suggesting a possible mechanism for AS to regulate sense expression. In atria, while alpha-MHC is not influenced by thyroid state, beta-MHC sense and AS RNA were simultaneously and inversely altered in response to T3. This confirms a close positive relationship between T3 and beta-MHC AS RNA in both the atria and ventricles, while demonstrating for the first time that alpha- and beta-MHC expression is not coupled in the atria.
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Affiliation(s)
- Sara Danzi
- Feinstein Institute for Medical Research and the Department of Medicine, North Shore University Hospital, Manhasset, New York
- Department of Medicine, NYU School of Medicine, Manhasset, New York
| | - Steven Klein
- Feinstein Institute for Medical Research and the Department of Medicine, North Shore University Hospital, Manhasset, New York
| | - Irwin Klein
- Feinstein Institute for Medical Research and the Department of Medicine, North Shore University Hospital, Manhasset, New York
- Department of Medicine, NYU School of Medicine, Manhasset, New York
- Department of Cell Biology, NYU School of Medicine, Manhasset, New York
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Poirier MB, Brunelle M, Langlois MF. The effect of RanBPM on the regulation of the hypothalamic–pituitary axis by thyroid hormone receptors is isoform-specific. Biochem Biophys Res Commun 2007; 362:516-21. [PMID: 17716622 DOI: 10.1016/j.bbrc.2007.08.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 08/03/2007] [Indexed: 11/18/2022]
Abstract
Although crucial for TH homeostasis, the molecular mechanisms responsible of thyroid hormone receptors (TRs)-mediated regulation of the hypothalamic-pituitary-thyroid axis (HPT) axis remain unclear. We examined the role played by TR-isoforms in combination with RanBPM, a novel coactivator of TRs. In transient transfections studies with the human TRH and TSH-alpha subunit promoters, we found that the overexpression of RanBPM increases the transcriptional activity of all TR-isoforms by a magnitude of 1.7- to 3-fold. The addition of RanBPM, in the absence of THs, increased the ligand-independent activation (LIA) of TRalpha1 and TRbeta1 on both promoters tested by 300% and 200%, respectively, whereas, the LIA of TRbeta2 was not significantly modified. This data reinforces the concept of isoform-specific regulation of genes of the HPT axis and demonstrates that RanBPM may be an important factor to achieve adequate regulation of nTREs in the presence of low TH levels.
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Affiliation(s)
- Marie-Belle Poirier
- Department of Medicine, Division of Endocrinology, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, C.H.U.S., 3001, 12th Avenue North, Sherbrooke, Que., Canada J1H 5N4
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Applebury ML, Farhangfar F, Glösmann M, Hashimoto K, Kage K, Robbins JT, Shibusawa N, Wondisford FE, Zhang H. Transient expression of thyroid hormone nuclear receptor TRβ2 sets S opsin patterning during cone photoreceptor genesis. Dev Dyn 2007; 236:1203-12. [PMID: 17436273 DOI: 10.1002/dvdy.21155] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cone photoreceptors in the murine retina are patterned by dorsal repression and ventral activation of S opsin. TR beta 2, the nuclear thyroid hormone receptor beta isoform 2, regulates dorsal repression. To determine the molecular mechanism by which TR beta 2 acts, we compared the spatiotemporal expression of TR beta 2 and S opsin from embryonic day (E) 13 through adulthood in C57BL/6 retinae. TR beta 2 and S opsin are expressed in cone photoreceptors only. Both are transcribed by E13, and their levels increase with cone genesis. TR beta 2 is expressed uniformly, but transiently, across the retina. mRNA levels are maximal by E17 at completion of cone genesis and again minimal before P5. S opsin is also transcribed by E13, but only in ventral cones. Repression in dorsal cones is established by E17, consistent with the occurrence of patterning during cone cell genesis. The uniform expression of TR beta 2 suggests that repression of S opsin requires other dorsal-specific factors in addition to TR beta 2. The mechanism by which TR beta 2 functions was probed in transgenic animals with TR beta 2 ablated, TR beta 2 that is DNA binding defective, and TR beta 2 that is ligand binding defective. These studies show that TR beta 2 is necessary for dorsal repression, but not ventral activation of S opsin. TR beta 2 must bind DNA and the ligand T3 (thyroid hormone) to repress S opsin. Once repression is established, T3 no longer regulates dorsal S opsin repression in adult animals. The transient, embryonic action of TR beta 2 is consistent with a role (direct and/or indirect) in chromatin remodeling that leads to permanent gene silencing in terminally differentiated, dorsal cone photoreceptors.
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Affiliation(s)
- M L Applebury
- The Howe Laboratory, Harvard Medical School and Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, USA.
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Hoo RLC, Chan KYY, Leung FKY, Lee LTO, Leung PCK, Chow BKC. Involvement of NF-κB subunit p65 and retinoic acid receptors, RARα and RXRα, in transcriptional regulation of the human GnRH II gene. FEBS J 2007; 274:2695-706. [PMID: 17451432 DOI: 10.1111/j.1742-4658.2007.05804.x] [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] [Indexed: 11/29/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) I and II are hypothalamic decapeptides with pivotal roles in the development of reproductive competence and regulation of reproductive events. In this study, transcriptional regulation of the human GnRH II gene was investigated. By scanning mutation analysis coupled with transient promoter assays, the motif at -641/-636 (CATGCC, designated GII-Sil) was identified as a repressor element. Mutation of this motif led to full restoration of promoter activity in TE671 medulloblastoma and JEG-3 placenta choriocarcinoma cells. Supershift and chromatin immunoprecipitation assays showed in vitro and in vivo binding of NF-kappaB subunit p65 and the retinoic acid receptors, RARalpha and RXRalpha, to the promoter sequences. Over-expression of these protein factors indicated that p65 is a potent repressor, and the RARalpha/RXRalpha heterodimer is involved in the differential regulation of the GnRH II gene in neuronal and placental cells. This was confirmed by quantitative real-time PCR. Treatment of cells with the RARalpha/RXRalpha ligands, all-trans retinoic acid and 9-cis-retinoic acid, reduced and increased GnRH II gene expression in TE671 and JEG-3 cells, respectively. Taken together, these data demonstrate the differential roles of NF-kappaB p65 and RARalpha/RXRalpha, interacting with the same sequence in the promoter of the human GnRH II gene to influence gene expression in a cell-specific manner.
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Affiliation(s)
- Ruby L C Hoo
- School of Biological Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, China
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35
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Moriyama K, Tagami T, Usui T, Naruse M, Nambu T, Hataya Y, Kanamoto N, Li YS, Yasoda A, Arai H, Nakao K. Antithyroid drugs inhibit thyroid hormone receptor-mediated transcription. J Clin Endocrinol Metab 2007; 92:1066-72. [PMID: 17192293 DOI: 10.1210/jc.2006-1621] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
CONTEXT Methimazole (MMI) and propylthiouracil (PTU) are widely used as antithyroid drugs (ATDs) for the treatment of Graves' disease. Both MMI and PTU reduce thyroid hormone levels by several mechanisms, including inhibition of thyroid hormone synthesis and secretion. In addition, PTU decreases 5'-deiodination of T(4) in peripheral tissues. ATDs may also interfere with T(3) binding to nuclear thyroid hormone receptors (TRs). However, the effect of ATDs on the transcriptional activities of T(3) mediated by TRs has not been studied. OBJECTIVE The present study was undertaken to determine whether ATDs have an effect on the gene transcription regulated by T(3) and TRs in vitro. METHODS Transient gene expression experiments and GH secretion assays were performed. To elucidate possible mechanisms of the antagonistic action of ATDs, the interaction between TR and nuclear cofactors was examined. RESULTS In the transient gene expression experiments, both MMI and PTU significantly suppressed transcriptional activities mediated by the TR and T(3) in a dose-dependent manner. In mammalian two-hybrid assays, both drugs recruited one of the nuclear corepressors, nuclear receptor corepressor, to the TR in the absence of T(3). In addition, PTU dissociated nuclear coactivators, such as steroid receptor coactivator-1 and glucocorticoid receptor interacting protein-1, from the TR in the presence of T(3). Finally, MMI decreased the GH release that was stimulated by T(3). CONCLUSIONS ATDs inhibit T(3) action by recruitment of transcriptional corepressors and/or dissociation of coactivators. This is the first report to show that ATDs can modulate T(3) action at the transcriptional level.
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Affiliation(s)
- Kenji Moriyama
- Division of Endocrinology and Metabolism, Clinical Research Institute, Kyoto Medical Center, National Hospital Organization, Kyoto 612-8555, Japan
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Kawakami Y, Adachi S, Yamauchi K, Ohta H. Thyroid hormone receptor beta is widely expressed in the brain and pituitary of the Japanese eel, Anguilla japonica. Gen Comp Endocrinol 2007; 150:386-94. [PMID: 17150218 DOI: 10.1016/j.ygcen.2006.10.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 10/02/2006] [Accepted: 10/21/2006] [Indexed: 11/20/2022]
Abstract
In a previous study, we cloned the thyroid hormone receptor betaB (TRbetaB) from a teleostean fish, the Japanese conger eel (Conger myriaster). The gene encoding this receptor is expressed in the brain and pituitary. In this study, we cloned TRbetaB from the brain of the Japanese eel (Anguilla japonica) to extend our studies into thyroid hormone function in fish. RT-PCR analysis demonstrated that the TRbetaB transcripts were abundant in both the brain and pituitary. The TRbetaB cDNA encoded a 379 amino acid protein with much higher homology to the conger eel TRbetaB than to other fish TRs, supporting the existence of a TRbetaB isoform, at least in anguilliforms. In a transiently transfected Japanese eel cell line, Hepa-E1, TRbetaB and its splice variants in the ligand-binding domain (TRbetaBL) showed thyroid hormone (TH)-dependent activation of transcription from the TH-responsive promoter. In situ hybridization studies revealed the presence of TRbetaB transcripts in the pars distalis of the pituitary.
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Affiliation(s)
- Y Kawakami
- Department of Fisheries, Graduate School of Agriculture, Kinki University, Nara 631-8505, Japan.
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37
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Matsushita A, Sasaki S, Kashiwabara Y, Nagayama K, Ohba K, Iwaki H, Misawa H, Ishizuka K, Nakamura H. Essential role of GATA2 in the negative regulation of thyrotropin beta gene by thyroid hormone and its receptors. Mol Endocrinol 2007; 21:865-84. [PMID: 17244762 DOI: 10.1210/me.2006-0208] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Previously we reported that the negative regulation of the TSHbeta gene by T(3) and its receptor [thyroid hormone receptor (TR)] is observed in CV1 cells when GATA2 and Pit1 are introduced. Using this system, we further studied the mechanism of TSHbeta inhibition. The negative regulatory element (NRE), which had been reported to mediate T(3)-bound TR (T(3)-TR)-dependent inhibition, is dispensable, because deletion or mutation of NRE did not impair suppression. The reporter construct, TSHbeta-D4-chloramphenicol acetyltransferase, which possesses only the binding sites for Pit1 and GATA2, was activated by GATA2 alone, and this transactivation was specifically inhibited by T(3)-TR. The Zn finger region of GATA2 interacts with the DNA-binding domain of TR in a T(3)-independent manner. The suppression by T(3)-TR was impaired by overexpression of a dominant-negative type TR-associated protein (TRAP) 220, an N- and C-terminal deletion construct, indicating the participation of TRAP220. Chromatin immunoprecipitation assays with a thyrotroph cell line, TalphaT1, revealed that T(3) treatment recruited histone deacetylase 3, reduced the acetylation of histone H4, and caused the dissociation of TRAP220 within 15-30 min. The reduction of histone H4 acetylation was transient, whereas the dissociation of TRAP220 persisted for a longer period. In the negative regulation of the TSHbeta gene by T(3)-TR we report that 1) GATA2 is the major transcriptional activator of the TSHbeta gene, 2) the putative NRE previously reported is not required, 3) TR-DNA-binding domain directly interacts with the Zn finger region of GATA2, and 4) histone deacetylation and TRAP220 dissociation are important.
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Affiliation(s)
- Akio Matsushita
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan
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Cowger JJM, Torchia J. Direct Association between the CREB-Binding Protein (CBP) and Nuclear Receptor Corepressor (N-CoR)†. Biochemistry 2006; 45:13150-62. [PMID: 17073437 DOI: 10.1021/bi060562g] [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] [Indexed: 11/28/2022]
Abstract
The binding of ligand to nuclear hormone receptors induces a conformational change that results in corepressor release and the recruitment of coactivator proteins that contain or recruit histone acetyltransferase (HAT) activity. As such, the coactivator and corepressor complexes and their associated HAT and histone deacytlase (HDAC) activities are often believed to be segregated into distinct complexes. However, there have been several reports that suggest that coactivators and corepressors may not be strictly segregated and in some cases even interact directly. In the present study, we have utilized a biochemical approach to assess whether the nuclear receptor corepressor (N-CoR) is capable of associating with the HAT coactivator CREB-binding protein (CBP). We demonstrate, using both immunoaffinity purification and conventional chromatography, that a subset of the N-CoR-HDAC3 complex copurifies with CBP in HeLa cells. In addition, indirect immunofluorescence also indicates an association between N-CoR and CBP in intact MCF-7 cells. This association may be direct as in vitro pulldown assays using recombinant purified proteins indicated that the amino terminus of N-CoR interacts directly with CBP. Interestingly, we also demonstrate that increasing concentrations of N-CoR are capable of attenuating CBP HAT activity in vitro, suggesting that N-CoR may have a functional role in modulating HAT activity. This is the first report of a direct interaction between N-CoR and CBP, and suggests that the role of N-CoR in mediating transcriptional events may be more complex than previously anticipated.
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Affiliation(s)
- Jeffery John Michael Cowger
- Department of Oncology, London Regional Cancer Program, The University of Western Ontario, London, Ontario N6A 4L6, Canada
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Hashimoto K, Yamada M, Matsumoto S, Monden T, Satoh T, Mori M. Mouse sterol response element binding protein-1c gene expression is negatively regulated by thyroid hormone. Endocrinology 2006; 147:4292-302. [PMID: 16794015 DOI: 10.1210/en.2006-0116] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Sterol regulatory element-binding protein (SREBP)-1c is a key regulator of fatty acid metabolism and plays a pivotal role in the transcriptional regulation of different lipogenic genes mediating lipid synthesis. In previous studies, the regulation of SREBP-1c mRNA levels by thyroid hormone has remained controversial. In this study, we examined whether T3 regulates the mouse SREBP-1c mRNA expression. We found that T3 negatively regulates the mouse SREBP-1c gene expression in the liver, as shown by ribonuclease protection assays and real-time quantitative RT-PCR. Promoter analysis with luciferase assays using HepG2 and Hepa1-6 cells revealed that T3 negatively regulates the mouse SREBP-1c gene promoter (-574 to +42) and that Site2 (GCCTGACAGGTGAAATCGGC) located around the transcriptional start site is responsible for the negative regulation by T3. Gel shift assays showed that retinoid X receptor-alpha/thyroid hormone receptor-beta heterodimer bound to Site2, but retinoid X receptor-alpha/liver X receptor- heterodimer could not bind to the site. In vivo chromatin immunoprecipitation assays demonstrated that T3 induced thyroid hormone receptor-beta recruitment to Site2. Thus, we demonstrated that mouse SREBP-1c mRNA is down-regulated by T3 in vivo and that T3 negatively regulates mouse SREBP-1c gene transcription via a novel negative thyroid hormone response element: Site2.
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Affiliation(s)
- Koshi Hashimoto
- Department of Medicine and Molecular Science, Graduate School of Medicine, Gunma University, 3-39-15 Showa-machi Maebashi, Gunma 371-8511, Japan.
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40
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Fukuyama K, Ichiki T, Imayama I, Ohtsubo H, Ono H, Hashiguchi Y, Takeshita A, Sunagawa K. Thyroid hormone inhibits vascular remodeling through suppression of cAMP response element binding protein activity. Arterioscler Thromb Vasc Biol 2006; 26:2049-55. [PMID: 16794221 DOI: 10.1161/01.atv.0000233358.87583.01] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Although accumulating evidences suggest that impaired thyroid function is a risk for ischemic heart disease, the molecular mechanism of anti-atherosclerotic effects of thyroid hormone is poorly defined. We examined whether thyroid hormone affects signaling pathway of angiotensin II (Ang II), which is critically involved in a broad aspect of cardiovascular disease process. METHODS AND RESULTS 3,3',5-triiodo-L-thyronine (T3) did not show a significant effect on Ang II-induced activation of extracellular signal-regulated protein kinase or p38 mitogen-activated protein kinase in vascular smooth muscle cells (VSMCs), whereas T3 inhibited Ang II-induced activation of cAMP response element (CRE) binding protein (CREB), a nuclear transcription factor involved in the vascular remodeling process. Coimmunoprecipitaion assay revealed the protein-protein interaction between thyroid hormone receptor and CREB. T3 reduced an expression level of interleukin (IL)-6 mRNA, CRE-dependent promoter activity, and protein synthesis induced by Ang II. Administration of T3 (100 microg/100 g for 14 days) to rats attenuated neointimal formation after balloon injury of carotid artery with reduced CREB activation and BrdU incorporation. CONCLUSIONS These results suggested that T3 inhibits CREB/CRE signaling pathway and suppresses cytokine expression and VSMCs proliferation, which may account for, at least in part, an anti-atherosclerotic effect of thyroid hormone.
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Affiliation(s)
- Kae Fukuyama
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, 3-1-1 Maidashi, Higashi-ku, 812-8582 Fukuoka, Japan
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41
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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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42
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Gordon DF, Tucker EA, Tundwal K, Hall H, Wood WM, Ridgway EC. MED220/thyroid receptor-associated protein 220 functions as a transcriptional coactivator with Pit-1 and GATA-2 on the thyrotropin-beta promoter in thyrotropes. Mol Endocrinol 2006; 20:1073-89. [PMID: 16396960 DOI: 10.1210/me.2005-0115] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mediator (MED) 220/thyroid receptor-associated protein (TRAP) 220 is a transcriptional mediator that interacts with liganded thyroid/steroid hormone receptors. MED220 haploinsufficient heterozygotes exhibited hypothyroidism and reduced TSHbeta transcripts, suggesting a specific function for TSHbeta transcription. We previously demonstrated that Pit-1 and GATA-2 can bind to a composite element within the proximal TSHbeta promoter and synergistically activate transcription. We detected MED220 expression in TtT-97 thyrotropes by Northern and Western blot analysis. Cotransfections in CV-1 cells showed that Pit-1, GATA-2, or MED220 alone did not markedly stimulate the TSHbeta promoter. However, Pit-1 plus GATA-2 resulted in an 10-fold activation, demonstrating synergistic cooperativity. Titration of MED220 resulted in a further dose-dependent stimulation up to 25-fold that was promoter specific. Glutathione-S-transferase interaction studies showed that MED220 or GATA-2 each bound the homeodomain of Pit-1, whereas MED220 interacted independently with each zinc finger of GATA-2 but not with either terminus. MED220 interacted with GATA-2 and Pit-1 over a broad region of its N terminus. These regions of interaction were also important for maximal function. Coimmunoprecipitation confirmed that all three factors can interact in thyrotropes and chromatin immunoprecipitation demonstrated in vivo occupancy on the proximal TSHbeta promoter. Thus, the TSHbeta gene is maximally activated by a combination of three thyrotrope transcription factors that act via both protein-DNA and protein-protein interactions.
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Affiliation(s)
- David F Gordon
- Division of Endocrinology, Department of Medicine, University of Colorado Health Sciences Center-Fitzsimons, Mail Stop 8106, P.O. Box 6511, Aurora, Colorado 80049, USA.
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Loinder K, Söderström M. An LXXLL motif in nuclear receptor corepressor mediates ligand-induced repression of the thyroid stimulating hormone-beta gene. J Steroid Biochem Mol Biol 2005; 97:322-7. [PMID: 16216492 DOI: 10.1016/j.jsbmb.2005.06.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Accepted: 06/23/2005] [Indexed: 10/25/2022]
Abstract
Nuclear receptor corepressor (N-CoR) regulates gene expression through interaction with DNA-bound nuclear receptors, recruiting multicomponent repressor complexes to the sites of target genes. We recently reported the presence of an LXXLL motif in N-CoR, and showed that this motif interacts in vitro and in vivo with retinoic acid receptor alpha (RARalpha) and thyroid hormone receptor beta (TRbeta). Transient transfection experiments now suggest that TRbeta and N-CoR act synergistically and may both be required for ligand-induced repression from the negative TR response element in the thyroid stimulating hormone-beta (TSHbeta) gene promoter. Mutation of the LXXLL motif in N-CoR abolished ligand-induced repression at this response element. Furthermore, in vitro binding of N-CoR to a complex between TRbeta and the negative TR response element was strictly ligand-dependent. We conclude that N-CoR and TRbeta cooperate in the regulation of the TSHbeta gene and that the ligand-dependent repression is mediated by the LXXLL motif in N-CoR.
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Affiliation(s)
- Kristina Loinder
- Division of Cell Biology, Department of Biomedicine and Surgery, Linköping University, S-581 85 Linköping, Sweden
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44
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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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45
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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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46
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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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47
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Carosa E, Radico C, Giansante N, Rossi S, D'Adamo F, Di Stasi SM, Lenzi A, Jannini EA. Ontogenetic profile and thyroid hormone regulation of type-1 and type-8 glucose transporters in rat Sertoli cells. ACTA ACUST UNITED AC 2005; 28:99-106. [PMID: 15811071 DOI: 10.1111/j.1365-2605.2005.00516.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The glucose transporters (GLUTs) gene encode glycoproteins responsible for facilitating transfer of glucose across plasma membrane. In testis, different members of this family are present. In particular the main GLUT mRNA expression within the adult testis is the type 8, while type 1 is more expressed in prepubertal testis. Thyroid hormone, which receptors and function have been characterized in the testis, plays a crucial role in the cellular energetic metabolism. In fact, in the immature Sertoli cells, GLUT1 is up regulated by l-triiodothyronine (T(3)). The aim of this paper is to investigate the expression profile of GLUT1 and GLUT8 in the testis during development and in adulthood and analyse the role of T(3) on their expression. To analyse the expression of GLUT8 and GLUT1 we performed Northern blot and RT-PCR experiments in the whole testis and in Sertoli cells from rats of different ages. Treatments in vivo and in vitro with T(3) were used to study the effect of thyroid hormones on GLUT1 and GLUT8 expression. The activity of the rat GLUT1 promoter and its regulation by T(3) was studied with transient transfections in gonadal and non-gonadal cell lines and in primary Sertoli cell cultures. GLUT8 is expressed at a low level in the prepubertal testis and Sertoli cells and does not appear to be under T(3) control. GLUT1 is the predominant form in immature Sertoli cells. The effect of T(3) on its mRNA accumulation was quantified and confirmed by RT-PCR (control: 0.65 +/- 0.17; T(3): 1.23 +/- 0.04, arbitrary units, p < 0.05). However, transfection experiments showed that T(3) does not directly regulate GLUT1 promoter in any cell line tested. This is confirmed by the evidence that, upon extensive analysis, the rat GLUT1 promoter and the first intron sequence do not shows any thyroid responsive elements. Our data demonstrate that GLUT1 and GLUT8 are both expressed in prepubertal testis, but only GLUT1 is regulated by T(3). In addition, we found that the effect of T(3) cannot be attributed to its action on GLUT1 promoter.
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Affiliation(s)
- Eleonora Carosa
- Course of Endocrinology and Medical Sexology, Department of Experimental Medicine, University of L'Aquila, 67100 L'Aquila, Italy
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48
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Constantinou C, Bolaris S, Valcana T, Margarity M. Acute LiCl-treatment affects the cytoplasmic T4 availability and the expression pattern of thyroid hormone receptors in adult rat cerebral hemispheres. Neurosci Res 2005; 51:235-41. [PMID: 15710487 DOI: 10.1016/j.neures.2004.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 11/16/2004] [Accepted: 11/22/2004] [Indexed: 11/20/2022]
Abstract
We have previously reported that short-term LiCl-treatment affects the kinetic characteristics of thyroid hormone binding in adult rat brain (Bolaris, S., Margarity, M., Valcana, T., 1995. Effects of LiCl on triiodothyronine (T3) binding to nuclei from rat cerebral hemispheres. Biol. Psychiatry 37, 106-111); however, the mechanism underlying the above effects of LiCl administration is yet to be determined. In this study, the effects of lithium within one day after its administration (5 mmol/kg BW) on the relative expression of thyroid hormone receptor isoforms and on the cytoplasmic and synaptosomal thyroid hormone availability in adult rat cerebral hemispheres were examined. Although short-term LiCl-treatment did not affect the levels of triiodothyronine either in the synaptosomal or in the cytoplasmic fraction 24 h after LiCl administration, the cytoplasmic availability of thyroxin was lower. In addition, 24 h after the administration of lithium the mRNA levels of the TRalpha1 isoform (T3 binding) increased while the relative expression of the TRalpha2 variant (non-T3 binding) was decreased. Notably, the decrease of the TRalpha2 mRNA levels was also observed 4h after LiCl administration. The expression levels of the TRbeta1 isoform were unaffected in any interval examined. The present study suggests that short-term lithium treatment regulates the relative expression of TRs in an isoform-specific manner and affects the cytoplasmic availability of thyroxin in adult rat brain.
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Affiliation(s)
- Caterina Constantinou
- Laboratory of Human and Animal Physiology, Department of Biology, University of Patras, Patras 265 00, Greece
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49
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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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50
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Furumoto H, Ying H, Chandramouli GVR, Zhao L, Walker RL, Meltzer PS, Willingham MC, Cheng SY. An unliganded thyroid hormone beta receptor activates the cyclin D1/cyclin-dependent kinase/retinoblastoma/E2F pathway and induces pituitary tumorigenesis. Mol Cell Biol 2005; 25:124-35. [PMID: 15601836 PMCID: PMC538780 DOI: 10.1128/mcb.25.1.124-135.2005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Thyroid-stimulating hormone (TSH)-secreting tumors (TSH-omas) are pituitary tumors that constitutively secrete TSH. The molecular genetics underlying this abnormality are not known. We discovered that a knock-in mouse harboring a mutated thyroid hormone receptor (TR) beta (PV; TRbeta(PV/PV) mouse) spontaneously developed TSH-omas. TRbeta(PV/PV) mice lost the negative feedback regulation with highly elevated TSH levels associated with increased thyroid hormone levels (3,3',5-triiodo-l-thyronine [T3]). Remarkably, we found that mice deficient in all TRs (TRalpha1(-/-) TRbeta(-/-)) had similarly increased T3 and TSH levels, but no discernible TSH-omas, indicating that the dysregulation of the pituitary-thyroid axis alone is not sufficient to induce TSH-omas. Comparison of gene expression profiles by cDNA microarrays identified overexpression of cyclin D1 mRNA in TRbeta(PV/PV) but not in TRalpha1(-/-) TRbeta(-/-) mice. Overexpression of cyclin D1 protein led to activation of the cyclin D1/cyclin-dependent kinase/retinoblastoma protein/E2F pathway only in TRbeta(PV/PV) mice. The liganded TRbeta repressed cyclin D1 expression via tethering to the cyclin D1 promoter through binding to the cyclic AMP response element-binding protein. That repression effect was lost in mutant PV, thereby resulting in constitutive activation of cyclin D1 in TRbeta(PV/PV) mice. The present study revealed a novel molecular mechanism by which an unliganded TRbeta mutant acts to contribute to pituitary tumorigenesis in vivo and provided mechanistic insights into the understanding of pathogenesis of TSH-omas in patients.
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Affiliation(s)
- Hiroko Furumoto
- Laboratory of Molecular Biology, National Cancer Institute, 37 Convent Drive, Rm. 5128, Bethesda, MD 20892-4264, USA
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