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Nambo M, Nishiwaki-Ohkawa T, Ito A, Ariki ZT, Ito Y, Kato Y, Yar M, Yim JCH, Kim E, Sharkey E, Kano K, Mishiro-Sato E, Okimura K, Maruyama M, Ota W, Furukawa Y, Nakayama T, Kobayashi M, Horio F, Sato A, Crudden CM, Yoshimura T. Synthesis and preclinical testing of a selective beta-subtype agonist of thyroid hormone receptor ZTA-261. COMMUNICATIONS MEDICINE 2024; 4:152. [PMID: 39107484 PMCID: PMC11303563 DOI: 10.1038/s43856-024-00574-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 07/04/2024] [Indexed: 08/10/2024] Open
Abstract
BACKGROUND Thyroid hormones (TH) regulate the basal metabolic rate through their receptors THRα and THRβ. TH activates lipid metabolism via THRβ, however, an excess amount of TH can lead to tachycardia, bone loss, and muscle wasting through THRα. In recent years, TH analogs that selectively bind to THRβ have gained attention as new agents for treating dyslipidemia and obesity, which continue to pose major challenges to public health worldwide. METHODS We developed a TH analog, ZTA-261, by modifying the existing THRβ-selective agonists GC-1 and GC-24. To determine the THRβ-selectivity of ZTA-261, an in vitro radiolabeled TH displacement assay was conducted. ZTA-261 was intraperitoneally injected into a mouse model of high-fat diet-induced obesity, and its effectiveness in reducing body weight and visceral fat, and improving lipid metabolism was assessed. In addition, its toxicity in the liver, heart, and bone was evaluated. RESULTS ZTA-261 is more selective towards THRβ than GC-1. Although ZTA-261 is less effective in reducing body weight and visceral fat than GC-1, it is as effective as GC-1 in reducing the levels of serum and liver lipids. These effects are mediated by the same pathway as that of T3, a natural TH, as evidenced by similar changes in the expression of TH-induced and lipid metabolism-related genes. The bone, cardiac, and hepatotoxicity of ZTA-261 are significantly lower than those of GC-1. CONCLUSIONS ZTA-261, a highly selective and less toxic THRβ agonist, has the potential to be used as a drug for treating diseases related to lipid metabolism.
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Affiliation(s)
- Masakazu Nambo
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
- Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
| | - Taeko Nishiwaki-Ohkawa
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
| | - Akihiro Ito
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Zachary T Ariki
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Yuka Ito
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Yuuki Kato
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Muhammad Yar
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
- Interdisciplinary Research Center in Biomedical Materials, COMSATS, University Islamabad Lahore Campus, Lahore, 54000, Pakistan
| | - Jacky C-H Yim
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Emily Kim
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Elizabeth Sharkey
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Keiko Kano
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Emi Mishiro-Sato
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Kosuke Okimura
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Michiyo Maruyama
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Wataru Ota
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Yuko Furukawa
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Tomoya Nakayama
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Misato Kobayashi
- Laboratory of Animal Nutrition, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
- Department of Nutritional Sciences, Nagoya University of Arts and Sciences, Nisshin, Aichi, 470-0196, Japan
| | - Fumihiko Horio
- Laboratory of Animal Nutrition, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
- Department of Life Studies and Environmental Science, Nagoya Women's University, Nagoya, 467-8610, Japan
| | - Ayato Sato
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
- Center for One Medicine Innovative Translational Research (COMIT), Nagoya University, Nagoya, 464-8601, Japan.
| | - Cathleen M Crudden
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
- Department of Chemistry, Queen's University, Chernoff Hall, Kingston, ON, K7L 3N6, Canada.
| | - Takashi Yoshimura
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
- Laboratory of Animal Integrative Physiology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
- Center for One Medicine Innovative Translational Research (COMIT), Nagoya University, Nagoya, 464-8601, Japan.
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Valduga JAG, Rebeiko LB, Skare TL. Prevalence of Hashimoto's thyroiditis in psoriasis patients. ACTA ACUST UNITED AC 2021; 67:52-57. [PMID: 34161490 DOI: 10.1590/1806-9282.67.01.20200274] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 09/20/2020] [Indexed: 02/08/2023]
Abstract
OBJECTIVE To study the prevalence of Hashimoto's Thyroiditis in a sample of psoriasis patients. METHODS Cross-sectional observational study of 120 individuals (60 with psoriasis and 60 control subjects) paired by gender and age for thyroid function (thyroid stimulating hormone, free T4), antithyroperoxidase and antithyroglobulin tests and physical examination. Psoriasis Area and Severity Index and Nail Psoriasis Severity Index were evaluated simultaneously. Epidemiological, clinical and treatment data was collected from medical records. Patients with documented hypothyroidism and/or goiter associated with positive antithyroperoxidase antibody were considered to have Hashimoto's Thyroiditis. RESULTS The prevalence of Hashimoto's Thyroiditis in the group with psoriasis was 21.6%; in the control group, it was 4/60 (6.6%) with p=0.03 (OR=3.8; 95%CI 1.18-12.6). In the group of patients with psoriasis, Hashimoto's Thyroiditis was more common in women (p=0.002) and less common in those who had polyarticular arthropathic psoriasis (p=0.05) and plaque psoriasis (p=0.005). A logistic regression showed that the only independent variable associated with Hashimoto's thyroiditis was plaque psoriasis. CONCLUSIONS There is a high prevalence of Hashimoto's Thyroiditis in psoriatic patients, especially in women. Hashimoto's Thyroiditis is less common in patients with the plaque form of psoriasis.
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Mahajan V, Rana A, Chauhan P, Mehta K, Sharma S, Sharma A, Sharma R. The association of thyroid dysfunction with chronic plaque psoriasis: A hospital-based retrospective descriptive observational study. Indian Dermatol Online J 2020; 11:771-776. [PMID: 33235844 PMCID: PMC7678532 DOI: 10.4103/idoj.idoj_432_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/11/2019] [Accepted: 11/26/2019] [Indexed: 01/10/2023] Open
Abstract
Background: Associations among thyroid dysfunction, thyroid autoimmunity, and clinical features including age, gender, disease duration, and severity of psoriasis is less studied. Objectives: To study frequency of thyroid dysfunction and thyroid autoimmunity and examine association among thyroid dysfunction, thyroid autoimmunity, and clinical features including gender, age, duration, and severity of psoriasis. Material and Methods: The medical records of 290 (m:f 2.15:1) patients aged 13–75 years with plaque psoriasis were analyzed for thyroid dysfunction and thyroid autoimmunity. Thyroid dysfunction was defined as 10% variation in any thyroid hormone levels. Thyroid autoimmunity was diagnosed from presence of antithyroid peroxide (anti-TPO) antibodies. Results: The majority, 57.9% patients, was aged ≥41 years (Type-2 psoriasis) and duration of disease was <5 years in 58.6% patients. Mild and moderate to severe psoriasis was present in 58.3% and 41.7% patients, respectively. Deranged thyroid functions were present in 29 (10%) patients. Hypothyroidism and hyperthyroidism occurred in 5.4% and 2.7% patients, respectively. Anti-TPO antibodies were observed in 13.5% patients; 11had hypothyroidism. There was no statistically significant difference in gender, age, duration, and severity of psoriasis when compared with patients having normal thyroid function tests. Conclusion: The study suggests possible thyroid dysregulation and thyroid autoimmunity in psoriasis but results need careful interpretation and clinical application. Their significance as standalone risk factor for the chronicity, severity, and relapses in psoriasis or whether thyroid hormone replacement or antithyroid drugs become a useful therapeutic option remains tenuous at best for need of more robust evidence. Retrospective, observational, cross-sectional study design, small number of patients, and lack of controls remain major limitations.
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Alidrisi HA, Al Hamdi K, Mansour AA. Is There Any Association Between Psoriasis and Hashimoto's Thyroiditis? Cureus 2019; 11:e4269. [PMID: 31157131 PMCID: PMC6529052 DOI: 10.7759/cureus.4269] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Background The association between psoriasis and Hashimoto’s thyroiditis has been evaluated in many retrospectives and prospective studies with varying numbers of patients and study designs. A positive association had been found certain studies, while no clear association in others. Objective The objective of this study was to evaluate the prevalence of Hashimoto’s thyroiditis in patients with psoriasis in comparison with healthy matched control from the same geographical region. Methods A case-control study was conducted from October 2017 to October 2018 in Faiha Specialized Diabetes, Endocrine, and Metabolism Center (FDEMC). Fifty-six psoriatic patients were compared with 54 healthy, gender, age and body mass index-matched controls. All participants had thyroid evaluation in the form of measurement of thyroid-stimulating hormone (TSH), free thyroxine (FT4), antithyroid peroxidase antibody (TPO Ab), and antithyroglobulin antibody (Tg Ab). Thyroid ultrasound examination was performed looking for volume, hypo-echogenicity, pseudo-nodularity, and increased vascularity. Assessment of psoriasis severity was conducted using the Psoriasis Area and Severity Index (PASI) score. Results Significantly higher prevalence of TPO Ab, Tg Ab, hypo-echogenicity, pseudo-nodularity, and increased vascularity was found in patients with psoriasis. The prevalence in psoriasis versus control was for TPO Ab (25.0% vs 9.3%, p = 0.02), Tg Ab (30.4% vs 11.1%, p = 0.01), hypo-echogenicity (30.4% vs 9.3%, p = 0.02), pseudo-nodularity (16.1% vs 0%, p = 0.002), and increased vascularity (35.7% vs 5.6%, p = 0.001). Patients with psoriasis with age of onset at diagnosis ≥40 years old and obesity were significantly more likely to have positive TPO Ab with a prevalence of (42.1% and 40.7%, respectively). There were no significant differences in the prevalence of hypothyroidism and subclinical hypothyroidism between psoriasis and control. In patients with psoriasis, psoriasis types, severity, duration, age, gender, smoking status, type 2 diabetes, and personal and family history of autoimmune diseases did not correlate with thyroid autoimmunity. Conclusions This study demonstrates a clear association between psoriasis and Hashimoto’s thyroiditis in the form of a significantly higher prevalence of TPO Ab, Tg Ab, hypo-echogenicity, pseudo-nodularity, and increased vascularity. Hence, thyroid evaluation by anti-thyroid antibodies, particularly TPO Ab, and ultrasound should be included in the care of psoriasis patients.
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Affiliation(s)
- Haider A Alidrisi
- Diabetes and Endocrinology, University of Basrah College of Medicine, Basrah, IRQ
| | - Khalil Al Hamdi
- Dermatology, University of Basrah College of Medicine, Basrah, IRQ
| | - Abbas A Mansour
- Diabetes and Endocrinology, University of Basrah College of Medicine, Basrah, IRQ
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5
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Mackenzie LS. Thyroid Hormone Receptor Antagonists: From Environmental Pollution to Novel Small Molecules. VITAMINS AND HORMONES 2018; 106:147-162. [DOI: 10.1016/bs.vh.2017.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Ertek S, Cicero AF. Hyperthyroidism and cardiovascular complications: a narrative review on the basis of pathophysiology. Arch Med Sci 2013; 9:944-52. [PMID: 24273583 PMCID: PMC3832836 DOI: 10.5114/aoms.2013.38685] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Revised: 07/28/2012] [Accepted: 08/20/2012] [Indexed: 01/02/2023] Open
Abstract
Cardiovascular complications are important in hyperthyroidism because of their high frequency in clinical presentation and increased mortality and morbidity risk. The cause of hyperthyroidism, factors related to the patient, and the genetic basis for complications are associated with risk and the basic underlying mechanisms are important for treatment and management of the disease. Besides cellular effects, hyperthyroidism also causes hemodynamic changes, such as increased preload and contractility and decreased systemic vascular resistance causes increased cardiac output. Besides tachyarrythmias, impaired systolic ventricular dysfunction and diastolic dysfunction may cause thyrotoxic cardiomyopathy in a small percentage of the patients, as another high mortality complication. Although the medical literature has some conflicting data about benefits of treatment of subclinical hyperthyroidism, even high-normal thyroid function may cause cardiovascular problems and it should be treated. This review summarizes the cardiovascular consequences of hyperthyroidism with underlying mechanisms.
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Affiliation(s)
- Sibel Ertek
- Ufuk University Medical Faculty, Dr. R. Ege Hospital, Endocrinology and Metabolic Diseases Department, Ankara, Turkey
| | - Arrigo F. Cicero
- Bologna University, Department of Internal Medicine, Aging and Kidney Diseases, Bologna, Italy
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7
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Association of psoriasis severity with serum prolactin, thyroid hormones, and cortisol before and after treatment. ScientificWorldJournal 2013; 2013:921819. [PMID: 24288511 PMCID: PMC3830895 DOI: 10.1155/2013/921819] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 09/08/2013] [Indexed: 01/18/2023] Open
Abstract
Background. Prolactin (PRL) level is proposed to be associated with the severity of psoriasis although the previous studies reported different results. Objective. To find the association between PRL levels and severity of psoriasis before and after treatment. In addition, we aimed to find a difference in prolactin, thyroid stimulating hormone (TSH), thyroid hormones (T3 and T4), and cortisol levels between patients with psoriasis and normal controls. Methods. First, the levels of hormones were measured in 30 patients with psoriasis and 30 matched controls. The severity was assessed by psoriasis area and severity index (PASI). Then, patients were treated, and PASI was assessed every week until achieving PASI-75 response. At this time, the hormones were measured again and compared to the baseline. Results. No statistical significant difference was observed in the mean PRL, T3, T4, TSH, and cortisol levels between cases and controls. Comparing to the baseline, a significant decrease in PRL levels and a significant increase in T3 and serum cortisol levels were observed after treatment (P < 0.05), while the changes in other hormones were not significant. Conclusion. After treatment, PRL significantly decreased, and T3 and cortisol levels significantly increased. No correlation between hormone levels and improvement of PASI score existed.
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Flood DEK, Fernandino JI, Langlois VS. Thyroid hormones in male reproductive development: evidence for direct crosstalk between the androgen and thyroid hormone axes. Gen Comp Endocrinol 2013; 192:2-14. [PMID: 23524004 DOI: 10.1016/j.ygcen.2013.02.038] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 02/24/2013] [Accepted: 02/26/2013] [Indexed: 01/06/2023]
Abstract
Thyroid hormones (THs) exert a broad range of effects on development in vertebrate species, demonstrating connections in nearly every biological endocrine system. In particular, studies have shown that THs play a role in sexual differentiation and gonadal development in mammalian and non-mammalian species. There is considerable evidence that the effects of THs on reproductive development are mediated through the female hormonal axis; however, recent findings suggest a more direct crosstalk between THs and the androgen axis. These findings demonstrate that THs have considerable influence in the sexual ontogeny of male vertebrates, through direct interactions with select sex-determining-genes and regulation of gonadotropin production in the hypothalamus-pituitary-gonad axis. THs also regulate androgen biosynthesis and signaling through direct and indirect regulation of steroidogenic enzyme expression and activity. Novel promoter analysis presented in this work demonstrates the potential for direct and vertebrate wide crosstalk at the transcriptional level in mice (Mus musculus), Western clawed frogs (Silurana tropicalis) and medaka (Oryzias latipes). Cumulative evidence from previous studies; coupled with novel promoter analysis suggests mechanisms for a more direct crosstalk between the TH and male reproductive axes across vertebrate species.
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Affiliation(s)
- Diana E K Flood
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, ON, Canada; Biology Department, Queen's University, Kingston, ON, Canada.
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Takano APC, Diniz GP, Barreto-Chaves MLM. AMPK signaling pathway is rapidly activated by T3 and regulates the cardiomyocyte growth. Mol Cell Endocrinol 2013; 376:43-50. [PMID: 23748029 DOI: 10.1016/j.mce.2013.05.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/27/2013] [Accepted: 05/30/2013] [Indexed: 01/07/2023]
Abstract
Previous studies have indicated that AMP-activated protein kinase (AMPK) plays a critical role in the control of cardiac hypertrophy mediated by different stimuli such as thyroid hormone (TH). Although the classical effects of TH mediating cardiac hypertrophy occur by transcriptional mechanisms, recent studies have identified other responses to TH, which are more rapid and take place in seconds or minutes evidencing that TH rapidly modulates distinct signaling pathway, which might contribute to the regulation of cardiomyocyte growth. Here, we evaluated the rapid effects of TH on AMPK signaling pathway in cultured cardiomyocytes and determined the involvement of AMPK in T3-induced cardiomyocyte growth. We found for the first time that T3 rapidly activated AMPK signaling pathway. The use of small interfering RNA against AMPK resulted in increased cardiomyocyte hypertrophy while the pharmacological stimulation of AMPK attenuated this process, demonstrating that AMPK contributes to regulation of T3-induced cardiomyocyte growth.
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Affiliation(s)
- Ana Paula Cremasco Takano
- Laboratory of Cell Biology and Functional Anatomy, Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-900, Brazil
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Diniz GP, Takano APC, Bruneto E, Silva FGD, Nunes MT, Barreto-Chaves MLM. New insight into the mechanisms associated with the rapid effect of T₃ on AT1R expression. J Mol Endocrinol 2012; 49:11-20. [PMID: 22525353 DOI: 10.1530/jme-11-0141] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The angiotensin II type 1 receptor (AT1R) is involved in the development of cardiac hypertrophy promoted by thyroid hormone. Recently, we demonstrated that triiodothyronine (T₃) rapidly increases AT1R mRNA and protein levels in cardiomyocyte cultures. However, the molecular mechanisms responsible for these rapid events are not yet known. In this study, we investigated the T₃ effect on AT1R mRNA polyadenylation in cultured cardiomyocytes as well as on the expression of microRNA-350 (miR-350), which targets AT1R mRNA. The transcriptional and translational actions mediated by T₃ on AT1R levels were also assessed. The total content of ubiquitinated proteins in cardiomyocytes treated with T₃ was investigated. Our data confirmed that T₃ rapidly raised AT1R mRNA and protein levels, as assessed by real-time PCR and western blotting respectively. The use of inhibitors of mRNA and protein synthesis prevented the rapid increase in AT1R protein levels mediated by T₃. In addition, T₃ rapidly increased the poly-A tail length of the AT1R mRNA, as determined by rapid amplification of cDNA ends poly-A test, and decreased the content of ubiquitinated proteins in cardiomyocytes. On the other hand, T₃ treatment increased miR-350 expression. In parallel with its transcriptional and translational effects on the AT1R, T₃ exerted a rapid posttranscriptional action on AT1R mRNA polyadenylation, which might be contributing to increase transcript stability, as well as on translational efficiency, resulting to the rapid increase in AT1R mRNA expression and protein levels. Finally, these results show, for the first time, that T₃ rapidly triggers distinct mechanisms, which might contribute to the regulation of AT1R levels in cardiomyocytes.
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Affiliation(s)
- Gabriela Placoná Diniz
- Department of Anatomy and Department of Physiology, Institute of Biomedical Sciences, University of São Paulo, Avenida Prof. Lineu Prestes 2415, Cidade Universitária, São Paulo SP 05508-900, Brazil
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Mishra P, Samanta L. Oxidative stress and heart failure in altered thyroid States. ScientificWorldJournal 2012; 2012:741861. [PMID: 22649319 PMCID: PMC3354657 DOI: 10.1100/2012/741861] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 12/25/2011] [Indexed: 02/07/2023] Open
Abstract
Increased or reduced action of thyroid hormone on certain molecular pathways in the heart and vasculature causes relevant cardiovascular derangements. It is well established that hyperthyroidism induces a hyperdynamic cardiovascular state, which is associated with a faster heart rate, enhanced left ventricular systolic and diastolic function whereas hypothyroidism is characterized by the opposite changes. Hyperthyroidism and hypothyroidism represent opposite clinical conditions, albeit not mirror images. Recent experimental and clinical studies have suggested the involvement of ROS tissue damage under altered thyroid status. Altered-thyroid state-linked changes in heart modify their susceptibility to oxidants and the extent of the oxidative damage they suffer following oxidative challenge. Chronic increase in the cellular levels of ROS can lead to a catastrophic cycle of DNA damage, mitochondrial dysfunction, further ROS generation and cellular injury. Thus, these cellular events might play an important role in the development and progression of myocardial remodeling and heart failure in altered thyroid states (hypo- and hyper-thyroidism). The present review aims at elucidating the various signaling pathways mediated via ROS and their modulation under altered thyroid state and the possibility of antioxidant therapy.
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Affiliation(s)
- Pallavi Mishra
- Department of Zoology, Utkal University, Odisha, Bhubaneswar 751004, India
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Structural basis for negative cooperativity within agonist-bound TR:RXR heterodimers. Proc Natl Acad Sci U S A 2012; 109:6084-7. [PMID: 22474364 DOI: 10.1073/pnas.1119852109] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Thyroid hormones such as 3,3',5 triiodo-L-thyronine (T3) control numerous aspects of mammalian development and metabolism. The actions of such hormones are mediated by specific thyroid hormone receptors (TRs). TR belongs to the nuclear receptor family of modular transcription factors that binds to specific DNA-response elements within target promoters. These receptors can function as homo- or heterodimers such as TR:9-cis retinoic acid receptor (RXR). Here, we present the atomic resolution structure of the TRα•T3:RXRα•9-cis retinoic acid (9c) ligand binding domain heterodimer complex at 2.95 Å along with T3 hormone binding and dissociation and coactivator binding studies. Our data provide a structural basis for allosteric communication between T3 and 9c and negative cooperativity between their binding pockets. In this structure, both TR and RXR are in the active state conformation for optimal binding to coactivator proteins. However, the structure of TR•T3 within TR•T3:RXR•9c is in a relative state of disorder, and the observed kinetics of binding show that T3 dissociates more rapidly from TR•T3:RXR•9c than from TR•T3:RXR. Also, coactivator binding studies with a steroid receptor coactivator-1 (receptor interaction domains 1-3) fragment show lower affinities (K(a)) for TR•T3:RXR•9c than TR•T3:RXR. Our study corroborates previously reported observations from cell-based and binding studies and offers a structural mechanism for the repression of TR•T3:RXR transactivation by RXR agonists. Furthermore, the recent discoveries of multiple endogenous RXR agonists that mediate physiological tasks such as lipid biosynthesis underscore the pharmacological importance of negative cooperativity in ligand binding within TR:RXR heterodimers.
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Abstract
The heart is an organ sensitive to the action of thyroid hormone, and measurable changes in cardiac performance are detected with small variations in thyroid hormone serum concentrations. Most patients with hyperthyroidism experience cardiovascular manifestations, and the most serious complications of hyperthyroidism occur as a result of cardiac involvement. Recent studies provide important insights into the molecular pathways that mediate the action of thyroid hormone on the heart and allow a better understanding of the mechanisms that underlie the hemodynamic and clinical manifestations of hyperthyroidism. Several cardiovascular conditions and drugs can interfere with thyroid hormone levels and may pose a difficulty in interpretation of laboratory data in patients with suspected thyroid heart disease. The focus of this report is a review of the current knowledge of thyroid hormone action on the heart and the clinical and hemodynamic laboratory findings as well as therapeutic management of patients with hyperthyroid heart disease.
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Affiliation(s)
- B M Fadel
- Division of Cardiovascular Medicine, Stanford University, California 94305-5406, USA
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Nishio N, Katsura T, Inui KI. Thyroid Hormone Regulates the Expression and Function of P-glycoprotein in Caco-2 Cells. Pharm Res 2007; 25:1037-42. [DOI: 10.1007/s11095-007-9495-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 01/26/2007] [Indexed: 10/22/2022]
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Kobayashi S, Shinohara H, Tabata K, Yamamoto N, Miyai A. Stereo structure-controlled and electronic structure-controlled estrogen-like chemicals to design and develop non-estrogenic bisphenol A analogs based on chemical hardness concept. Chem Pharm Bull (Tokyo) 2007; 54:1633-8. [PMID: 17139095 DOI: 10.1248/cpb.54.1633] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to elucidate the structure-activity relationship of bisphenol A (BPA) analogs using absolute hardness (eta) and absolute electronegativity (chi) (chemical hardness) and to design a non-estrogen active BPA. To determine the structure-activity relationships of BPA analogs, we investigated MCF-7 cell proliferation stimulated by BPA analogs and an eta-chi diagram based on the electronic structure of the BPA analogs. The results show that the actions of the environmental hormones BPA analogs have two chemical properties; (i) 'stereo structure-controlled' and (ii) 'electronic structure-controlled' estrogen-like chemical activities. Therefore, we designed and synthesized BPA analogs which do not possess these 2 characteristics, ((i) and (ii)), and demonstrate the non-estrogen activity of the analog.
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Affiliation(s)
- Shigeki Kobayashi
- Department of Analytical Chemistry of Medicines, Showa Pharmaceutical University, Tokyo, Japan.
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16
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17
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Nishio N, Katsura T, Ashida K, Okuda M, Inui KI. Modulation of P-glycoprotein expression in hyperthyroid rat tissues. Drug Metab Dispos 2005; 33:1584-7. [PMID: 16079271 DOI: 10.1124/dmd.105.004770] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
P-glycoprotein (Pgp) is expressed in various normal tissues and plays an important role in drug absorption and disposition. In addition, it is supposed that alterations in the expression levels of Pgp are involved in the inter- and intraindividual variability of pharmacokinetics of many drugs. Since pharmacokinetic properties of various drugs are altered in patients with thyroid disorders, we examined the expression of Pgp and mdr1a/1b mRNA in the kidney, liver, jejunum, and ileum from euthyroid and hyperthyroid rats. Western blot analysis revealed that Pgp expression was markedly increased in the kidney and liver of hyperthyroid rats. In contrast, it was slightly increased in the jejunum and ileum. mdr1a/1b mRNA levels were significantly increased in the kidney of hyperthyroid rats. However, they were not increased in the liver as well as in the jejunum and ileum of hyperthyroid rats. Expression levels of bile salt export pump and mdr2 mRNA were also unchanged in hyperthyroid rat liver. Taken together, these findings suggest that thyroid hormone induces Pgp expression in a tissue-selective manner, and that the modulation of mdr1a/1b mRNA expression in the hyperthyroid state varies among tissues.
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Affiliation(s)
- Naoki Nishio
- Department of Pharmacy, Kyoto University Hospital, Kyoto 606-8507, Japan
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18
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Zhang F, Yajima T, Li YZ, Xu GZ, Chen HL, Liu QT, Yamauchi O. Iodine-Assisted Assembly of Helical Coordination Polymers of Cucurbituril and Asymmetric Copper(II) Complexes. Angew Chem Int Ed Engl 2005; 44:3402-7. [PMID: 15844115 DOI: 10.1002/anie.200463071] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Feng Zhang
- State Key Laboratory of Coordination Chemistry, Nanjing University, 22 Hankou Road, Nanjing 210093, P.R. China
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19
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Zhang F, Yajima T, Li YZ, Xu GZ, Chen HL, Liu QT, Yamauchi O. Iodine-Assisted Assembly of Helical Coordination Polymers of Cucurbituril and Asymmetric Copper(II) Complexes. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200463071] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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Santos GM, Pantoja CJ, Costa e Silva A, Rodrigues MC, Ribeiro RC, Simeoni LA, Lomri N, Neves FAR. Thyroid hormone receptor binding to DNA and T3-dependent transcriptional activation are inhibited by uremic toxins. NUCLEAR RECEPTOR 2005; 3:1. [PMID: 15807894 PMCID: PMC1087878 DOI: 10.1186/1478-1336-3-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Accepted: 04/04/2005] [Indexed: 12/14/2022]
Abstract
Background There is a substantial clinical overlap between chronic renal failure (CRF) and hypothyroidism, suggesting the presence of hypothyroidism in uremic patients. Although CRF patients have low T3 and T4 levels with normal thyroid-stimulating hormone (TSH), they show a higher prevalence of goiter and evidence for blunted tissue responsiveness to T3 action. However, there are no studies examining whether thyroid hormone receptors (TRs) play a role in thyroid hormone dysfunction in CRF patients. To evaluate the effects of an uremic environment on TR function, we investigated the effect of uremic plasma on TRβ1 binding to DNA as heterodimers with the retinoid X receptor alpha (RXRα) and on T3-dependent transcriptional activity. Results We demonstrated that uremic plasma collected prior to hemodialysis (Pre-HD) significantly reduced TRβ1-RXRα binding to DNA. Such inhibition was also observed with a vitamin D receptor (VDR) but not with a peroxisome proliferator-activated receptor gamma (PPARγ). A cell-based assay confirmed this effect where uremic pre-HD ultrafiltrate inhibited the transcriptional activation induced by T3 in U937 cells. In both cases, the inhibitory effects were reversed when the uremic plasma and the uremic ultrafiltrate were collected and used after hemodialysis (Post-HD). Conclusion These results suggest that dialyzable toxins in uremic plasma selectively block the binding of TRβ1-RXRα to DNA and impair T3 transcriptional activity. These findings may explain some features of hypothyroidism and thyroid hormone resistance observed in CRF patients.
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Affiliation(s)
- Guilherme M Santos
- Molecular Pharmacology Laboratory, Department of Pharmaceutical Sciences, School of Health Sciences, University of Brasilia, Brazil
- University of Cergy-Pontoise, UFR des Sciences et Techniques, ERRMECe Laboratory, BP222, 2 Ave Adolphe Chauvin, 95302 Cergy-Pontoise, France
| | - Carlos J Pantoja
- Molecular Pharmacology Laboratory, Department of Pharmaceutical Sciences, School of Health Sciences, University of Brasilia, Brazil
| | | | - Maria C Rodrigues
- Molecular Pharmacology Laboratory, Department of Pharmaceutical Sciences, School of Health Sciences, University of Brasilia, Brazil
| | | | - Luiz A Simeoni
- Molecular Pharmacology Laboratory, Department of Pharmaceutical Sciences, School of Health Sciences, University of Brasilia, Brazil
| | - Noureddine Lomri
- University of Cergy-Pontoise, UFR des Sciences et Techniques, ERRMECe Laboratory, BP222, 2 Ave Adolphe Chauvin, 95302 Cergy-Pontoise, France
| | - Francisco AR Neves
- Molecular Pharmacology Laboratory, Department of Pharmaceutical Sciences, School of Health Sciences, University of Brasilia, Brazil
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21
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Estébanez-Perpiñá E, Moore JMR, Mar E, Delgado-Rodrigues E, Nguyen P, Baxter JD, Buehrer BM, Webb P, Fletterick RJ, Guy RK. The Molecular Mechanisms of Coactivator Utilization in Ligand-dependent Transactivation by the Androgen Receptor. J Biol Chem 2005; 280:8060-8. [PMID: 15563469 DOI: 10.1074/jbc.m407046200] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Androgens drive sex differentiation, bone and muscle development, and promote growth of hormone-dependent cancers by binding the nuclear androgen receptor (AR), which recruits coactivators to responsive genes. Most nuclear receptors recruit steroid receptor coactivators (SRCs) to their ligand binding domain (LBD) using a leucine-rich motif (LXXLL). AR is believed to recruit unique coactivators to its LBD using an aromatic-rich motif (FXXLF) while recruiting SRCs to its N-terminal domain (NTD) through an alternate mechanism. Here, we report that the AR-LBD interacts with both FXXLF motifs and a subset of LXXLL motifs and that contacts with these LXXLL motifs are both necessary and sufficient for SRC-mediated AR regulation of transcription. Crystal structures of the activated AR in complex with both recruitment motifs reveal that side chains unique to the AR-LBD rearrange to bind either the bulky FXXLF motifs or the more compact LXXLL motifs and that AR utilizes subsidiary contacts with LXXLL flanking sequences to discriminate between LXXLL motifs.
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Affiliation(s)
- Eva Estébanez-Perpiñá
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, USA
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22
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Barra GB, Velasco LFR, Pessanha RP, Campos AM, Moura FN, Dias SMG, Polikarpov I, Ribeiro RCJ, Simeoni LA, Neves FAR. [Molecular mechanism of thyroid hormone action]. ACTA ACUST UNITED AC 2004; 48:25-39. [PMID: 15611816 DOI: 10.1590/s0004-27302004000100005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Thyroid hormones (TH) are involved in normal differentiation, growth, and metabolism in several tissues of all vertebrates. Their actions are mediated by the TH receptors (TRs), members of the nuclear hormone receptor superfamily. These receptors are transcription factors that bind to DNA on specific sequences, the TR response element (TREs), in promoters of target genes. Two genes encode TRs, alpha e beta, located in chromosomes 17 and 3, respectively. These isoforms show different functions and exhibit a tissue specific expression. TRs function as monomers, homodimers or heterodimers with retinoid X receptor (RXR) and modulate transcription activity (repression or activation) by interacting with co-repressor and co-activators, which associate with TR in the absence or presence of T3, respectively. Understanding the molecular mechanism of TR action and the definition of its crystallographic structure will provide new insights into transcription mechanisms and will facilitate the design of new drugs with greater therapeutic value.
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Affiliation(s)
- Gustavo B Barra
- Laboratório de Farmacologia Molecular, Departamento de Ciências Farmacêuticas, Faculdade de Ciências da Saúde, Universidade de Brasília, Brasília, DF
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23
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Webb P, Nguyen NH, Chiellini G, Yoshihara HAI, Cunha Lima ST, Apriletti JW, Ribeiro RCJ, Marimuthu A, West BL, Goede P, Mellstrom K, Nilsson S, Kushner PJ, Fletterick RJ, Scanlan TS, Baxter JD. Design of thyroid hormone receptor antagonists from first principles. J Steroid Biochem Mol Biol 2002; 83:59-73. [PMID: 12650702 DOI: 10.1016/s0960-0760(02)00270-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is desirable to obtain TR antagonists for treatment of hyperthyroidism and other conditions. We have designed TR antagonists from first principles based on TR crystal structures. Since agonist ligands are buried in the fold of the TR ligand binding domain (LBD), we reasoned that ligands that resemble agonists with large extensions should bind the LBD, but would prevent its folding into an active conformation. In particular, we predicted that extensions at the 5' aryl position of ligand should reposition helix (H) 12, which forms part of the co-activator binding surface, and thereby inhibit TR activity. We have found that some synthetic ligands with 5' aryl ring extensions behave as antagonists (DIBRT, NH-3), or partial antagonists (GC-14, NH-4). Moreover, one compound (NH-3) represents the first potent TR antagonist with nanomolar affinity that also inhibits TR action in an animal model. However, the properties of the ligands also reveal unexpected aspects of TR behavior. While nuclear receptor antagonists generally promote binding of co-repressors, NH-3 blocks co-activator binding and also prevents co-repressor binding. More surprisingly, many compounds with extensions behave as full or partial agonists. We present hypotheses to explain both behaviors in terms of dynamic equilibrium of H12 position.
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Affiliation(s)
- Paul Webb
- Diabetes Center and Metabolic Research Unit, University of California, San Francisco, CA 94143, USA.
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24
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Ashida K, Katsura T, Motohashi H, Saito H, Inui KI. Thyroid hormone regulates the activity and expression of the peptide transporter PEPT1 in Caco-2 cells. Am J Physiol Gastrointest Liver Physiol 2002; 282:G617-23. [PMID: 11897620 DOI: 10.1152/ajpgi.00344.2001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
An oligopeptide transporter (PEPT1) in the small intestine plays an important role in the absorption of small peptides and peptide-like drugs. We examined the effect of thyroid hormone 3,5,3'-L-triiodothyronine (T(3)) on the activity and expression of PEPT1 in human intestinal Caco-2 cells. Treatment of Caco-2 cells with T(3) inhibited [(14)C]glycylsarcosine uptake in a time- and dose-dependent manner. [(14)C]glycylsarcosine uptake was reduced by pretreatment of the cells with 100 nM T(3) for 4 days (67% of control value), whereas methyl-alpha-D-[U-(14)C]glucopyranoside and [(3)H]threonine uptake were not decreased. Kinetic analysis showed that T(3) treatment significantly decreased the maximum uptake (V(max)) value for [(14)C]glycylsarcosine uptake but had no effect on the K(m) value. Moreover, T(3) treatment caused a significant decrease in the amount of PEPT1 mRNA (25% of the control). Western blotting indicated that the amount of PEPT1 protein in the apical membrane was decreased (70% of the control). These findings indicate that T(3) treatment inhibits the uptake of [(14)C]glycylsarcosine by decreasing the transcription and/or stability of PEPT1 mRNA.
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Affiliation(s)
- Kayoko Ashida
- Department of Pharmacy, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
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25
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Clarke BL, Degroot LJ. Thyroid Hormone Regulation of Islet Cell Hormone Metabolic Actions. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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26
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Alrefai WA, Tyagi S, Mansour F, Saksena S, Syed I, Ramaswamy K, Dudeja PK. Sulfate and chloride transport in Caco-2 cells: differential regulation by thyroxine and the possible role of DRA gene. Am J Physiol Gastrointest Liver Physiol 2001; 280:G603-13. [PMID: 11254486 DOI: 10.1152/ajpgi.2001.280.4.g603] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The current studies were undertaken to establish an in vitro cellular model to study the transport of SO and Cl(-) and hormonal regulation and to define the possible function of the downregulated in adenoma (DRA) gene. Utilizing a postconfluent Caco-2 cell line, we studied the OH(-) gradient-driven (35)SO and (36)Cl(-) uptake. Our findings consistent with the presence of an apical carrier-mediated (35)SO/OH(-) exchange process in Caco-2 cells include: 1) demonstration of saturation kinetics [Michaelis-Menten constant (K(m)) of 0.2 +/- 0.08 mM for SO and maximum velocity of 1.1 +/- 0.2 pmol x mg protein(-1) x 2 min(-1)]; 2) sensitivity to inhibition by DIDS (K(i) = 0.9 +/- 0.3 microM); and 3) competitive inhibition by oxalate and Cl(-) but not by nitrate and short chain fatty acids, with a higher K(i) (5.95 +/- 1 mM) for Cl(-) compared with oxalate (K(i) = 0.2 +/- 0.03 mM). Our results also suggested that the SO/OH(-) and Cl(-)/OH(-) exchange processes in Caco-2 cells are distinct based on the following: 1) the SO/OH(-) exchange was highly sensitive to inhibition by DIDS compared with Cl(-)/OH(-) exchange activity (K(i) for DIDS of 0.3 +/- 0.1 mM); 2) Cl(-) competitively inhibited the SO/OH(-) exchange activity with a high K(i) compared with the K(m) for SO, indicating a lower affinity for Cl(-); 3) DIDS competitively inhibited the Cl(-)/OH(-) exchange process, whereas it inhibited the SO/OH(-) exchange activity in a mixed-type manner; and 4) utilizing the RNase protection assay, our results showed that 24-h incubation with 100 nM of thyroxine significantly decreased the relative abundance of DRA mRNA along with the SO/OH(-) exchange activity but without any change in Cl(-)/OH(-) exchange process. In summary, these studies demonstrated the feasibility of utilizing Caco-2 cell line as a model to study the apical SO/OH(-) and Cl(-)/OH(-) exchange processes in the human intestine and indicated that the two transporters are distinct and that DRA may be predominantly a SO transporter with a capacity to transport Cl(-) as well.
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Affiliation(s)
- W A Alrefai
- Section of Digestive and Liver Diseases, Department of Medicine, University of Illinois at Chicago and West Side Veterans Affairs Medical Center, Chicago, Illinois 60612, USA
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27
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Baxter JD, Dillmann WH, West BL, Huber R, Furlow JD, Fletterick RJ, Webb P, Apriletti JW, Scanlan TS. Selective modulation of thyroid hormone receptor action. J Steroid Biochem Mol Biol 2001; 76:31-42. [PMID: 11384861 DOI: 10.1016/s0960-0760(01)00052-8] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Thyroid hormones have some actions that might be useful therapeutically, but others that are deleterious. Potential therapeutically useful actions include those to induce weight loss and lower plasma cholesterol levels. Potential deleterious actions are those on the heart to induce tachycardia and arrhythmia, on bone to decrease mineral density, and on muscle to induce wasting. There have been successes in selectively modulating the actions of other classes of hormones through various means, including the use of pharmaceuticals that have enhanced affinities for certain receptor isoforms. Thus, there is reason to pursue selective modulation of thyroid hormone receptor (TR) function, and several agents have been shown to have some beta-selective, hepatic selective and/or cardiac sparring activities, although development of these was largely not based on detailed understanding of mechanisms for the specificity. The possibility of selectively targeting the TRbeta was suggested by the findings that there are alpha- and beta-TR forms and that the TRalpha-forms may preferentially regulate the heart rate, whereas many other actions of these hormones are mediated by the TRbeta. We determined X-ray crystal structures of the TRalpha and TRbeta ligand-binding domains (LBDs) complexed with the thyroid hormone analog 3,5,3'-triiodithyroacetic acid (Triac). The data suggested that a single amino acid difference in the ligand-binding cavities of the two receptors could affect hydrogen bonding in the receptor region, where the ligand's 1-position substituent fits and might be exploited to generate beta-selective ligands. The compound GC-1, with oxoacetate in the 1-position instead of acetate as in Triac, exhibited TRbeta-selective binding and actions in cultured cells. An X-ray crystal structure of the GC-1-TRbeta LBD complex suggests that the oxoacetate does participate in a network of hydrogen bonding in the TR LBD polar pocket. GC-1 displayed actions in tadpoles that were TRbeta-selective. When administered to mice, GC-1 was as effective in lowering plasma cholesterol levels as T(3), and was more effective than T(3) in lowering plasma triglyceride levels. At these doses, GC-1 did not increase the heart rate. GC-1 was also less active than T(3) in modulating activities of several other cardiac parameters, and especially a cardiac pacemaker channel such as HCN-2, which may participate in regulation of the heart rate. GC-1 showed intermediate activity in suppressing plasma thyroid stimulating hormone (TSH) levels. The tissue/plasma ratio for GC-1 in heart was also less than for the liver. These data suggest that compounds can be generated that are TR-selective and that compounds with this property and/or that exhibit selective uptake, might have clinical utility as selective TR modulators.
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Affiliation(s)
- J D Baxter
- Metabolic Research Unit, Department of Medicine, University of California, San Francisco, CA 94143, USA.
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28
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Schaufele F, Chang CY, Liu W, Baxter JD, Nordeen SK, Wan Y, Day RN, McDonnell DP. Temporally distinct and ligand-specific recruitment of nuclear receptor-interacting peptides and cofactors to subnuclear domains containing the estrogen receptor. Mol Endocrinol 2000; 14:2024-39. [PMID: 11117532 DOI: 10.1210/mend.14.12.0572] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Ligand binding to estrogen receptor (ER) is presumed to regulate the type and timing of ER interactions with different cofactors. Using fluorescence microscopy in living cells, we characterized the recruitment of five different green fluorescent protein (GFP)-labeled ER-interacting peptides to the distinct subnuclear compartment occupied by blue fluorescent protein (BFP)-labeled ER alpha. Different ligands promoted the recruitment of different peptides. One peptide was recruited in response to estradiol (E2), tamoxifen, raloxifene, or ICI 182,780 incubation whereas other peptides were recruited specifically by E2 or tamoxifen. Peptides containing different sequences surrounding the ER-interacting motif LXXLL were recruited with different time courses after E2 addition. Complex temporal kinetics also were observed for recruitment of the full-length, ER cofactor glucocorticoid receptor-interacting protein 1 (GRIP1); rapid, E2-dependent recruitment of GRIP1 was blocked by mutation of the GRIP1 LXXLL motifs to LXXAA whereas slower E2 recruitment persisted for the GRIP1 LXXAA mutant. This suggested the presence of multiple, temporally distinct GRIP 1 recruitment mechanisms. E2 recruitment of GRIP1 and LXXLL peptides was blocked by coincubation with excess ICI 182,780. In contrast, preformed E2/ER/GRIP1 and E2/ER/LXXLL complexes were resistant to subsequent ICI 182,780 addition whereas ICI 182,780 dispersed preformed complexes containing the GRIP1 LXXAA mutant. This suggested that E2-induced LXXLL binding altered subsequent ligand/ER interactions. Thus, alternative, ligand-selective recruitment and dissociation mechanisms with distinct temporal sequences are available for ER alpha action in vivo.
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Affiliation(s)
- F Schaufele
- Department of Medicine, University of California San Francisco, 94143, USA
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29
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Fang X, Hillgartner FB. Alterations in retinoid X receptor-alpha expression contribute to cell-type dependent differences in thyroid hormone regulation of malic enzyme transcription. Mol Cell Endocrinol 2000; 164:41-52. [PMID: 11026556 DOI: 10.1016/s0303-7207(00)00238-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Triiodothyronine (T3) stimulates a marked increase (> 40-fold) in transcription of the malic enzyme gene in chick embryo hepatocytes (CEH), but has no effect on malic enzyme transcription in chick embryo fibroblasts (CEF) that express nuclear T3 receptors (TR) at levels which are similar to those of CEH. Heterodimerization of the TR with other nuclear proteins is a potential mechanism for the regulation of T3 action. For example, heterodimers of retinoid X receptors (RXR) and TR bind to T3 response elements (T3RE) with higher affinity and modulate transcription more effectively than TR homodimers. In the present report, we investigated the role of RXR in mediating differences in T3 responsiveness of the malic enzyme gene between CEH and CEF. Data from gel mobility shift analyses demonstrated that endogenous TRs from CEH and CEF bind to the major T3RE of the malic enzyme gene primarily as heterodimers with RXR alpha or a protein highly related to RXR alpha. The total binding activity of RXR alpha/TR complexes in CEF was decreased relative to that observed in CEH. Cell-type dependent differences in RXR alpha/TR complex formation were greater in cells incubated in the presence of T3 because T3 treatment increased RXR alpha/TR binding activity in CEH but had no effect on RXR alpha/TR binding activity in CEF. Decreased RXR alpha/TR complex formation in CEF relative to CEH was associated with a reduction in the abundance of RXR alpha protein and RXR alpha mRNA in the former cell-type. Expression of exogenous RXR alpha in CEF increased the T3 responsiveness of the malic enzyme promoter by about 4-fold. In contrast, expression of exogenous RXR alpha in CEH had no effect on the regulation of malic enzyme transcription by T3. These observations support the hypothesis that alterations in RXR alpha expression contribute to cell-type dependent differences in T3 responsiveness of the malic enzyme gene.
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Affiliation(s)
- X Fang
- Department of Biochemistry, School of Medicine, West Virginia University, Morgantown 26506, USA
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30
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Billoni N, Buan B, Gautier B, Gaillard O, Mahé YF, Bernard BA. Thyroid hormone receptor beta1 is expressed in the human hair follicle. Br J Dermatol 2000; 142:645-52. [PMID: 10792213 DOI: 10.1046/j.1365-2133.2000.03408.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To understand better the mechanisms by which thyroid hormone can exert its effects on the hair follicle, we looked for the expression of members of the thyroid hormone receptor (TR) family in human hair follicles. Immunoreactive TRs were detected in both dermal and epithelial compartments of the human pilosebaceous unit. Using reverse transcriptase-polymerase chain reaction, we established that TRbeta1 was the predominant form of TR expressed in the human hair follicle. In addition, we investigated the effects of 3,3', 5-triiodo-L-thyronine (T3) on the survival of human hair follicles in vitro, to understand the role of this thyroid hormone on hair follicle homeostasis. A physiological level of free T3 significantly enhanced human hair survival in vitro.
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Affiliation(s)
- N Billoni
- Life Sciences, L'OREAL Advanced Research Laboratories, L'OREAL Hair Biology Group, 90 rue du général Roguet, 92583 Clichy cedex, France
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31
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Yoh SM, Privalsky ML. Resistance to thyroid hormone (RTH) syndrome reveals novel determinants regulating interaction of T3 receptor with corepressor. Mol Cell Endocrinol 2000; 159:109-24. [PMID: 10687857 DOI: 10.1016/s0303-7207(99)00201-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Thyroid hormone receptors (T3Rs) both repress and activate gene transcription by interacting with auxiliary factors denoted corepressors and coactivators. Resistance to thyroid hormone (RTH) syndrome in humans is manifested as a failure to respond properly to elevated circulating thyroid hormone. RTH syndrome has been mapped to T3Rbeta mutations that alter the transcriptional properties of the receptor, resulting in a dominant negative phenotype. We report here a characterization of a series of RTH mutant T3Rs that exhibit unusual interactions with corepressor. Two mutations in receptor helix 11 (delta430, delta432) greatly enhance the ability of the mutant receptors to bind to corepressor. A distinct mutation, V264D, in an 'omega loop' region of the receptor, impairs corepressor release but does not fully eliminate the ability to recruit coactivator. These mutations reveal novel determinants that regulate the interaction of the T3R with important ancillary cofactors, and that are disrupted in a human endocrine disease.
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Affiliation(s)
- S M Yoh
- Division of Biological Sciences, University of California at Davis, 95616, USA.
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32
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Zhu J, Miura K, Chen L, Raikhel AS. AHR38, a homolog of NGFI-B, inhibits formation of the functional ecdysteroid receptor in the mosquito Aedes aegypti. EMBO J 2000; 19:253-62. [PMID: 10637229 PMCID: PMC305559 DOI: 10.1093/emboj/19.2.253] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In anautogenous mosquitoes, vitellogenesis, the key event in egg maturation, requires a blood meal. Consequently, mosquitoes are vectors of numerous devastating human diseases. After ingestion of blood, 20-hydroxyecdysone activates yolk protein precursor (YPP) genes in the metabolic tissue, the fat body. An important adaptation for anautogenicity is the previtellogenic developmental arrest (the state-of-arrest) preventing the activation of YPP genes in previtellogenic females prior to blood feeding. Here, we show that a retinoid X receptor homolog, Ultraspiracle (AaUSP), which is an obligatory partner in the functional ecdysteroid receptor, exists at the state-of-arrest as a heterodimer with the orphan nuclear receptor AHR38, a homolog of Drosophila DHR38 and nerve growth factor-induced protein B. Yeast two-hybrid and glutathione S-transferase pull-down assays demonstrate that AHR38 can interact strongly with AaUSP. AHR38 also disrupts binding of ecdysteroid receptor to ecdysone response elements. Cell co-transfection of AHR38 with AaEcR and AaUSP inhibits ecdysone-dependent activation of a reporter gene by the ecdysteroid receptor. Co-immunoprecipitation experiments indicate that AaUSP protein associates with AHR38 instead of AaEcR in fat body nuclei at the state-of-arrest.
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Affiliation(s)
- J Zhu
- Program in Genetics and Department of Entomology, Michigan State University, East Lansing, MI 488240-1115, USA
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33
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Yang Z, Hong SH, Privalsky ML. Transcriptional anti-repression. Thyroid hormone receptor beta-2 recruits SMRT corepressor but interferes with subsequent assembly of a functional corepressor complex. J Biol Chem 1999; 274:37131-8. [PMID: 10601274 PMCID: PMC2701910 DOI: 10.1074/jbc.274.52.37131] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thyroid hormone receptors (T3Rs) are hormone-regulated transcription factors. Different T3R isoforms are expressed in a tissue-specific and developmentally regulated manner. The T3Ralpha-1, beta-0, and beta-1 isoforms typically repress target gene expression in the absence of hormone and activate transcription in the presence of hormone. Intriguingly, however, the T3Rbeta-2 isoform fails to repress, and instead is able to activate transcription in both the absence and presence of hormone. We investigated the molecular mechanism behind this absence of repression by T3Rbeta-2. Repression by T3Ralpha-1, beta-0, and beta-1 is mediated by the ability of these isoforms to physically recruit a SMRT/N-CoR corepressor complex. We determined that the unliganded T3Rbeta-2 also recruits the SMRT corepressor; in contrast to the alpha-1, beta-0, and beta-1 isoforms, however, the T3Rbeta-2 protein interacts not only with the C-terminal "receptor-interaction domain" of SMRT, but also makes additional contacts with the N-terminal "silencing domain" of the SMRT corepressor. These additional, T3Rbeta-2-specific contacts interfere with the subsequent association of SMRT with mSin3, a crucial second subunit of the corepressor holo-complex. Our results suggest that T3Rbeta-2 regulates transcription through a novel anti-repression mechanism, recruiting SMRT, but preventing the subsequent formation of a functional corepressor complex.
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Affiliation(s)
| | | | - Martin L. Privalsky
- To whom correspondence should be addressed. Tel.: 530−752−3013; Fax: 530−752−9014; E-mail:
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Ballock RT, Mita BC, Zhou X, Chen DH, Mink LM. Expression of thyroid hormone receptor isoforms in rat growth plate cartilage in vivo. J Bone Miner Res 1999; 14:1550-6. [PMID: 10469283 DOI: 10.1359/jbmr.1999.14.9.1550] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Although thyroid hormone has been known for many years to be a potent regulator of skeletal maturation in vivo, it has not definitively been determined whether this effect is a result of a direct or indirect action of the hormone. Previous in vivo studies have suggested that thyroid hormone may stimulate longitudinal bone growth by increasing the secretion of growth hormone; however, growth hormone alone is unable to stimulate cartilage maturation. There are also indications that thyroid hormone is able to act directly on growth plate chondrocytes through growth hormone-independent mechanisms. In this study, we demonstrate that rat growth plate chondrocytes in vivo express genes encoding three of the four isoforms of the thyroid hormone receptors described to date, but the corresponding protein can only be detected for the TRalpha1 and TRbeta1 isoforms of the receptor. As has been noted in other tissues, there is generally poor correlation between the mRNA levels for each isoform and the relative amount of corresponding protein as measured by immunoblotting, suggesting the possibility that receptor expression may be regulated by post-transcriptional mechanisms.
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Affiliation(s)
- R t Ballock
- Pediatric Orthopaedic Research Laboratory, Department of Orthopaedics, Case Western Reserve University, Rainbow Babies and Children's Hospital, University Hospitals of Cleveland, Ohio 44106, USA
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35
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Hong SH, Privalsky ML. Retinoid isomers differ in the ability to induce release of SMRT corepressor from retinoic acid receptor-alpha. J Biol Chem 1999; 274:2885-92. [PMID: 9915825 PMCID: PMC2701912 DOI: 10.1074/jbc.274.5.2885] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nuclear hormone receptors are ligand-regulated transcription factors that modulate the expression of specific target genes in response to the binding of small, hydrophobic hormone ligands. Many nuclear hormone receptors, such as the retinoic acid receptors, can both repress and activate target gene expression; these bimodal transcription properties are mediated by the ability of these receptors to tether auxiliary factors, denoted corepressors and coactivators. Corepressors are typically bound by receptors in the absence of cognate hormone, whereas binding of an appropriate hormone agonist induces an allosteric alteration in the receptor resulting in release of the corepressor and recruitment of coactivator. Structural analysis indicates that there is a close induced fit between the hormone ligand and the receptor polypeptide chain. This observation suggests that different ligands, once bound, may confer distinct conformations on the receptor that may invoke, in turn, distinct functional consequences. We report here that different retinoids do differ in the ability to release corepressor once bound to retinoic acid receptor and suggest that these differences in corepressor release may manifest as differences in transcriptional regulation.
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Affiliation(s)
| | - Martin L. Privalsky
- To whom correspondence should be addressed. Tel.: 530−752−3013; Fax: 530−752−9014; E-mail:
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36
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Cano A, Baum M, Moe OW. Thyroid hormone stimulates the renal Na/H exchanger NHE3 by transcriptional activation. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:C102-8. [PMID: 9886925 PMCID: PMC4099556 DOI: 10.1152/ajpcell.1999.276.1.c102] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Thyroid hormone stimulates renal proximal tubule NaCl and NaHCO3 absorption in part by activating the apical membrane Na/H exchanger NHE3. We used a renal epithelial cell line, the opossum kidney (OK) cell, to define the mechanism by which 3,5,3'-triiodothyronine (T3) increases NHE3 activity. T3 stimulated NHE3 activity, an effect that was blocked by inhibition of cellular transcription or translation. The increase in activity was associated with increases in steady-state cell surface and total cellular NHE3 protein and NHE3 transcript abundance. T3 stimulated transcription of the NHE3 gene and had no effect on NHE3 transcript stability. The transcriptional activity of the 5'-flanking region of the rat NHE3 gene was stimulated by T3 when expressed in OK cells. When heterologously expressed rat NHE3 transcript levels were clamped constant with a constitutive promoter in OK cells, T3 has no effect on rat NHE3 protein abundance, suggesting the absence of regulation of NHE3 protein stability or translation. These studies demonstrate that T3 stimulates NHE3 activity by activating NHE3 gene transcription and increasing NHE3 transcript and protein abundance.
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Affiliation(s)
- A Cano
- Department of Internal Medicine,University of Texas Medical Center, Dallas, Texas 75235-8856, USA
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37
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Nagaya T, Murata Y, Yamaguchi S, Nomura Y, Ohmori S, Fujieda M, Katunuma N, Yen PM, Chin WW, Seo H. Intracellular proteolytic cleavage of 9-cis-retinoic acid receptor alpha by cathepsin L-type protease is a potential mechanism for modulating thyroid hormone action. J Biol Chem 1998; 273:33166-73. [PMID: 9837884 DOI: 10.1074/jbc.273.50.33166] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously reported that the responsiveness of hepatocytes to thyroid hormone is markedly attenuated when they were cultured as monolayers rather than spheroids. To elucidate the mechanisms underlying the altered responsiveness, thyroid hormone receptor auxiliary proteins in the hepatocytes were analyzed by electrophoretic mobility shift assay. The major thyroid hormone receptor auxiliary protein was identified as 9-cis-retinoic acid receptor alpha (RXRalpha) in the hepatocytes regardless of the culture conditions. The cytoplasmic fraction was shown to contain a protease(s) that cleaves RXRalpha at its amino terminus. The presence of the protease in the cytosol, but not in the nucleus, was ascertained by incubating full-length 35S-labeled RXRalpha with each fraction. Using various protease inhibitors, it was shown that cathepsin L-type protease could participate in the cleavage of the RXRalpha. The enzyme activity was much higher in the monolayers than the spheroids. Inhibition of this enzyme activity in the monolayer hepatocyte resulted in the increase of nuclear RXRalpha protein and the augmentation of T3-dependent induction of spot 14 mRNA. These results suggest that the changes in cathepsin L-type protease activity in the cytosol may alter the turnover of RXRalpha in the nucleus and modify the function of steroid receptor superfamilies that heterodimerize with RXRalpha.
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Affiliation(s)
- T Nagaya
- Department of Endocrinology and Metabolism, Division of Molecular and Cellular Adaptation, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan
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38
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Apriletti JW, Ribeiro RC, Wagner RL, Feng W, Webb P, Kushner PJ, West BL, Nilsson S, Scanlan TS, Fletterick RJ, Baxter JD. Molecular and structural biology of thyroid hormone receptors. CLINICAL AND EXPERIMENTAL PHARMACOLOGY & PHYSIOLOGY. SUPPLEMENT 1998; 25:S2-11. [PMID: 9809185 DOI: 10.1111/j.1440-1681.1998.tb02293.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. Thyroid hormone receptors (TR) are expressed from two separate genes (alpha and beta) and belong to the nuclear receptor superfamily, which also contains receptors for steroids, vitamins and prostaglandins. 2. Unliganded TR are bound to DNA thyroid hormone response elements (TRE) predominantly as homodimers, or as heterodimers with retinoid X-receptors (RXR), and are associated with a complex of proteins containing corepressor proteins. Ligand binding promotes corepressor dissociation and binding of a coactivator. 3. Recent studies from our group have focused on the acquisition and use of X-ray crystallographic structures of ligand-binding domains (LBD) of both the rat (r) TR alpha and the human (h) TR beta bound to several different ligands. We have also developed ligands that bind selectively to the TR beta, which may provide ways to explore the differential functions of TR alpha compared with TR beta isoforms. 4. The LBD is comprised mostly of alpha-helices. The ligand is completely buried in the receptor and forms part of its hydrophobic core. Kinetic studies suggest that the limiting step in formation of high-affinity ligand-receptor complexes is the rate of folding of the receptor around the ligand. Ligands can be fitted tightly in the ligand-binding pocket and small differences in this fitting may explain many structure-activity relationships. Interestingly, analysis of the structures of antagonists suggests that they have chemical groups, 'extensions', that could impair receptor folding around them and, thus, prevent the agonist-induced conformation changes in the receptor. 5. The TR structures allowed us to see that the mutations that occur in the syndrome of generalized resistance to thyroid hormone are located in the vicinity of the ligand-binding pocket. 6. X-ray structure of the TR has also been used to guide construction of mutations in the TR surface that block binding of various proteins important for receptor function. Studies with these TR mutants reveal that the interfaces for homo- and heterodimerization map to similar residues in helix 10 and 11 and also allow the definition of the surface for binding of coactivators, which appears to be general for nuclear receptors. Formation of this surface, which involves packing of helix 12 of the TR into a scaffold formed by helices 3 and 5, appears to be the major change in the receptor structure induced by hormone occupancy.
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Affiliation(s)
- J W Apriletti
- Metabolic Research Unit, University of California, San Francisco 94143-0540, USA.
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39
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Wong CW, Privalsky ML. Transcriptional silencing is defined by isoform- and heterodimer-specific interactions between nuclear hormone receptors and corepressors. Mol Cell Biol 1998; 18:5724-33. [PMID: 9742089 PMCID: PMC109158 DOI: 10.1128/mcb.18.10.5724] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/1998] [Accepted: 07/07/1998] [Indexed: 12/24/2022] Open
Abstract
Nuclear hormone receptors are ligand-regulated transcription factors that play critical roles in metazoan homeostasis, development, and reproduction. Many nuclear hormone receptors exhibit bimodal transcriptional properties and can either repress or activate the expression of a given target gene. Repression appears to require a physical interaction between a receptor and a corepressor complex containing the SMRT/TRAC or N-CoR/RIP13 polypeptides. We wished to better elucidate the rules governing the association of receptors with corepressors. We report here that different receptors interact with different domains in the SMRT and N-CoR corepressors and that these divergent interactions may therefore contribute to distinct repression phenotypes. Intriguingly, different isoforms of a single nuclear hormone receptor class also differ markedly in their interactions with corepressors, indicative of their nonidentical actions in cellular regulation. Finally, we present evidence that combinatorial interactions between different receptors can, through the formation of heterodimeric receptors, result in novel receptor-corepressor interactions not observed for homomeric receptors.
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Affiliation(s)
- C W Wong
- Section of Microbiology, Division of Biological Sciences, University of California at Davis, Davis, California 95616, USA
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40
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Drvota V, Blange I, Häggblad J, Sylvén C. Desethylamiodarone prolongation of cardiac repolarization is dependent on gene expression: a novel antiarrhythmic mechanism. J Cardiovasc Pharmacol 1998; 32:654-61. [PMID: 9781936 DOI: 10.1097/00005344-199810000-00020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Desethylamiodarone (DEA) is the major metabolite of amiodarone and has similar electrophysiologic effects with prolongation of the repolarization that is reversed by thyroid hormone (T3). Some of the electrophysiologic effects are probably due to antagonism of T3 at the receptor level. Such effects of T3 are mediated by modulation of gene transcription. The aim of this study was to investigate whether cycloheximide (Cy), an inhibitor of protein synthesis, and actinomycin D (ActD), a RNA-synthesis inhibitor, block DEA-induced prolongation of the repolarization and whether DEA takes part in the autoregulation of the nuclear thyroid hormone-receptor subtypes (ThR). Corrected monophasic action potentials (MAPc) and QTc were measured in Langendorff-perfused guinea pig hearts for 1 h. The hearts were continuously perfused with (a) vehicle, (b) 7.5 microM Cy, (c) 5 microM DEA, (d) 5 microM DEA + 7.5 microM Cy, (e) 1 microM T3, (f) 5 microM DEA + 1 microM T3, (g) 1.5 microM ActD, and (h) ActD + DEA. A potassium channel blocker with class III antiarrhythmic effects, 0.5 microM almokalant, was used as a control, separately and together with Cy. Western blot analysis for the ThR subtypes alpha, beta1, and beta2 was performed on vehicle- and DEA-treated hearts. DEA increased MAPc by 19% (p < 0.0005) and QTc by 18% (p < 0.0005). There was no effect on MAPc or QTc when Cy, ActD, or T3 was added with DEA. Almokalant increased MAPc by 14% (p < 0.005) and QTc by 13% (p < 0.0005). When Cy was present, almokalant still induced a similar prolongation of MAPc by 14% (p < 0.005) and QTc by 17% (p < 0.0005). Western blot analysis revealed no change in the expression of the ThR protein. In conclusion, the prolongation of the cardiac repolarization by DEA, but not almokalant, can be totally blocked by Cy and ActD. This indicates that the class III action of DEA is at least in part dependent on transcription rather than a direct effect on cell-membrane channels or receptors. The action of DEA could be reversed by T3, indicating an antagonism between DEA and T3. These results suggest a new antiarrhythmic mechanism dependent on gene expression.
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Affiliation(s)
- V Drvota
- Department of Cardiology, Karolinska Institute, Huddinge University Hospital, Sweden
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41
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Hong SH, Wong CW, Privalsky ML. Signaling by tyrosine kinases negatively regulates the interaction between transcription factors and SMRT (silencing mediator of retinoic acid and thyroid hormone receptor) corepressor. Mol Endocrinol 1998; 12:1161-71. [PMID: 9717842 PMCID: PMC2653426 DOI: 10.1210/mend.12.8.0160] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Nuclear hormone receptors are hormone-regulated transcription factors that bind to specific sites on DNA and modulate the expression of adjacent target genes. Many nuclear hormone receptors display bimodal transcriptional properties; thyroid hormone receptors, for example, typically repress target gene expression in the absence of hormone, but activate target gene expression in the presence of hormone. The ability to repress is closely linked to the ability of the apo-receptor to physically bind to auxiliary corepressor proteins denoted SMRT (silencing mediator of retinoic acid and thyroid hormone receptor) and N-CoR (nuclear receptor corepressor), which, in turn, help mediate the actual molecular events involved in transcriptional silencing. We report here that repression by thyroid hormone receptors can be regulated not only by cognate hormone, but also by certain tyrosine kinase signal transduction pathways, such as that represented by the epidermal growth factor-receptor. Activation of tyrosine kinase signaling leads to inhibition of T3R-mediated repression with relatively little effect on activation. These effects appear to be mediated by a kinase-initiated disruption of the ability of T3R to interact with SMRT corepressor. Intriguingly, tyrosine kinase signaling similarly disrupted the interactions of SMRT with v-Erb A, with retinoic acid receptors, and with PLZF, a nonreceptor transcriptional repressor. We conclude that tyrosine kinase signaling exerts potentially important regulatory effects on transcriptional silencing mediated by a variety of transcription factors that operate through the SMRT corepressor complex.
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Affiliation(s)
- S H Hong
- Section of Microbiology, Division of Biological Sciences, University of California at Davis, 95616, USA
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42
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Chiellini G, Apriletti JW, Yoshihara HA, Baxter JD, Ribeiro RC, Scanlan TS. A high-affinity subtype-selective agonist ligand for the thyroid hormone receptor. CHEMISTRY & BIOLOGY 1998; 5:299-306. [PMID: 9653548 DOI: 10.1016/s1074-5521(98)90168-5] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Thyroid hormones regulate many different physiological processes in different tissues in vertebrates. Most of the actions of thyroid hormones are mediated by the thyroid hormone receptor (TR), which is a member of the nuclear receptor superfamily of ligand-activated transcription regulators. There are two different genes that encode two different TRs, TR alpha and TR beta, and these two TRs are often co-expressed at different levels in different tissues. Most thyroid hormones do not discriminate between the two TRs and bind both with similar affinities. RESULTS We have designed and synthesized a thyroid hormone analog that has high affinity for the TRs and is selective in both binding and activation functions for TR beta over TR alpha. The compound, GC-1, was initially designed to solve synthetic problems that limit thyroid hormone analog preparation, and contains several structural changes with respect to the natural hormone 3,5,3'-triiodo-L-thyronine (T3). These changes include replacement of the three iodines with methyl and isopropyl groups, replacement of the biaryl ether linkage with a methylene linkage, and replacement of the amino-acid sidechain with an oxyacetic-acid sidechain. CONCLUSIONS The results of this study show that GC-1 is a member of a new class of thyromimetic compounds that are more synthetically accessible than traditional thyromimetics and have potentially useful receptor binding and activation properties. The TR beta selectivity of GC-1 is particularly interesting and suggests that GC-1 might be a useful in vivo probe for studying the physiological roles of the different thyroid hormone receptor isoforms.
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Affiliation(s)
- G Chiellini
- Department of Pharmaceutical Chemistry, University of California, San Francisco 94143-0446, USA
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43
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Tzagarakis-Foster C, Privalsky ML. Phosphorylation of thyroid hormone receptors by protein kinase A regulates DNA recognition by specific inhibition of receptor monomer binding. J Biol Chem 1998; 273:10926-32. [PMID: 9556570 DOI: 10.1074/jbc.273.18.10926] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Thyroid hormone receptor (T3R) alpha-1 and its oncogenic derivative, the v-ERB A protein, are phosphorylated by cAMP-dependent protein kinase A. Although this phosphorylation appears to be necessary for the oncogenic properties of v-ERB A, the mechanism by which phosphorylation influences the functions of v-ERB A and of the normal T3R has not been established. The protein kinase A phosphorylation site in T3Ralpha-1 is within a domain that is known to contribute to the DNA recognition properties of these receptors. We therefore analyzed the effects of protein kinase A phosphorylation on DNA recognition by the normal T3Ralpha and by the v-ERB A oncoprotein. We report here that phosphorylation of these receptor derivatives does not significantly alter the overall affinity of receptor dimers for DNA. However, phosphorylation does notably alter DNA recognition by preventing, or greatly inhibiting, the ability of these receptors to bind to DNA as protein monomers. These studies suggest that the phosphorylation of T3Ralpha-1 and v-ERB A by protein kinase A may provide a means of altering promoter recognition through a post-translational modification.
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Affiliation(s)
- C Tzagarakis-Foster
- Section of Microbiology and Section of Molecular and Cellular Biology, Division of Biological Sciences, University of California, Davis, California 95616, USA
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44
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Ribeiro RC, Apriletti JW, Wagner RL, Feng W, Kushner PJ, Nilsson S, Scanlan TS, West BL, Fletterick RJ, Baxter JD. X-ray crystallographic and functional studies of thyroid hormone receptor. J Steroid Biochem Mol Biol 1998; 65:133-41. [PMID: 9699866 DOI: 10.1016/s0960-0760(98)00029-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We have solved several X-ray crystallographic structures of TR ligand-binding domains (LBDs), including the rat (r) TR alpha and the human (h) TR beta bound to diverse ligands. The TR-LBD folding, comprised mostly of alpha-helices, is likely to be general for the superfamily. The ligand, buried in the receptor, forms part of its hydrophobic core. Tight fitting of ligand into the receptor explains its high affinity for the TR, although the structure suggests that ligands with even higher affinities might be generated. The kinetics of 3,5,3'-triiodo-L-thyronine (T3) and 3,5,3',5'-tetraiodo-L-thyronine (T4) binding suggest that folding around the ligand, rather than receptor opening, is rate-limiting for high affinity binding. TR beta mutations in patients with resistance to T3 cluster around the ligand; these different locations could differentially affect on other receptor functions and explain the syndrome's clinical diversity. Guided by the structure, mutations have been placed on the TR surface to define interactions with other proteins. They suggest that a similar surface in the LBD is utilized for homo- or heterodimerization on direct repeats and inverted palindromes but not on palindromes. Coactivator proteins that mediate TR transcriptional activation bind to a small surface comprised of residues on four helices with a well-defined hydrophobic cleft, which may be a target for pharmaceuticals. The coactivator-binding surface appears to form upon ligand-binding by the folding of helix 12 into the scaffold formed by helices 3, 4 and 5. The analysis of most currently used antagonists suggest that although they probably fit into the ligand-binding pocket, they possess a group that may alter proper folding of the receptor, with disruption of the coactivator-binding surface (the 'extension model').
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Affiliation(s)
- R C Ribeiro
- Department of Medicine, University of California, San Francisco 94143-0540, USA
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45
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46
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Lin BC, Hong SH, Krig S, Yoh SM, Privalsky ML. A conformational switch in nuclear hormone receptors is involved in coupling hormone binding to corepressor release. Mol Cell Biol 1997; 17:6131-8. [PMID: 9315673 PMCID: PMC232463 DOI: 10.1128/mcb.17.10.6131] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Nuclear hormone receptors are ligand-regulated transcription factors that modulate gene expression in response to small, hydrophobic hormones, such as retinoic acid and thyroid hormone. The thyroid hormone and retinoic acid receptors typically repress transcription in the absence of hormone and activate it in the presence of hormone. Transcriptional repression is mediated, in part, through the ability of these receptors to physically associate with ancillary polypeptides called corepressors. We wished to understand the mechanism by which corepressors are recruited to unliganded nuclear hormone receptors and are released on the binding of hormone. We report here that an alpha-helical domain located at the thyroid hormone receptor C terminus appears to undergo a hormone-induced conformational change required for release of corepressor and that amino acid substitutions that abrogate this conformational change can impair or prevent corepressor release. In contrast, retinoid X receptors appear neither to undergo an equivalent conformational alteration in their C termini nor to release corepressor in response to cognate hormone, consistent with the distinct transcriptional regulatory properties displayed by this class of receptors.
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Affiliation(s)
- B C Lin
- Division of Biological Sciences, University of California at Davis, 95616, USA
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47
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Leitman DC, Costa CH, Graf H, Baxter JD, Ribeiro RC. Thyroid hormone activation of transcription is potentiated by activators of cAMP-dependent protein kinase. J Biol Chem 1996; 271:21950-5. [PMID: 8703000 DOI: 10.1074/jbc.271.36.21950] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We characterized the cross-talk between activators of protein kinase A (PKA) and thyroid hormone (T3) in T3 receptor (TR)-mediated transcription. U937 cells were cotransfected with a plasmid expressing the TR and a reporter plasmid containing a T3 response element (TRE) oriented either as a direct repeat or as a palindrome upstream of the thymidine kinase promoter linked to the chloramphenicol acetyltransferase gene. T3 activated transcription by 10-fold. T3 response was potentiated 2.5-3-fold by activators of PKA, but an activator of protein kinase C or of guanylate kinase was ineffective. In the absence of T3, activators of PKA had no effect on transcription. TR heterodimerization with the retinoid X receptor may facilitate T3/PKA cross-talk because coexpression of the retinoid X receptor potentiated cross-talk. Synergy was not observed in JEG-3, F9, CV-1, HeLa, L929, and HTC cells, indicating that it may require cell-specific factors. Synergy required the DNA- and ligand-binding domains, but not the amino-terminal domain, indicating that T3- and TRE-induced conformational changes on the TR are essential for cross-talk. PKA phosphorylated the TR in vitro, suggesting that, like other nuclear receptors, the TR is a target for PKA. These results imply that PKA cross-talks with T3 at the level of the TRE-bound TR, enhancing its transcriptional activity in a cell-specific manner.
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Affiliation(s)
- D C Leitman
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco 94143-0540, USA
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Wagner RL, Apriletti JW, McGrath ME, West BL, Baxter JD, Fletterick RJ. A structural role for hormone in the thyroid hormone receptor. Nature 1995; 378:690-7. [PMID: 7501015 DOI: 10.1038/378690a0] [Citation(s) in RCA: 649] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The crystal structure of the rat alpha 1 thyroid hormone receptor ligand-binding domain bound with a thyroid hormone agonist reveals that ligand is completely buried within the domain as part of the hydrophobic core. In addition, the carboxy-terminal activation domain forms an amphipathic helix, with its hydrophobic face constituting part of the hormone binding cavity. These observations suggest a structural role for ligand, in establishing the active conformation of the receptor, that is likely to underlie hormonal regulation of gene expression for the nuclear receptors.
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Affiliation(s)
- R L Wagner
- Graduate Group in Biophysics, University of California at San Francisco 94143-0448, USA
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