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Abstract
The present review traces the road leading to discovery of L-thyroxine, thyroid hormone (3,5,3´-triiodo-L-thyronine, T3) and its cognate nuclear receptors. Thyroid hormone is a pleio-tropic regulator of growth, differentiation, and tissue homeostasis in higher organisms. The major site of the thyroid hormone action is predominantly a cell nucleus. T3 specific binding sites in the cell nuclei have opened a new era in the field of the thyroid hormone receptors (TRs) discovery. T3 actions are mediated by high affinity nuclear TRs, TRalpha and TRbeta, which function as T3-activated transcription factors playing an essential role as transcription-modulating proteins affecting the transcriptional responses in target genes. Discovery and characterization of nuclear retinoid X receptors (RXRs), which form with TRs a heterodimer RXR/TR, positioned RXRs at the epicenter of molecular endocrinology. Transcriptional control via nuclear RXR/TR heterodimer represents a direct action of thyroid hormone. T3 plays a crucial role in the development of brain, it exerts significant effects on the cardiovascular system, skeletal muscle contractile function, bone development and growth, both female and male reproductive systems, and skin. It plays an important role in maintaining the hepatic, kidney and intestine homeostasis and in pancreas, it stimulates the beta-cell proliferation and survival. The TRs cross-talk with other signaling pathways intensifies the T3 action at cellular level. The role of thyroid hormone in human cancers, acting via its cognate nuclear receptors, has not been fully elucidated yet. This review is aimed to describe the history of T3 receptors, starting from discovery of T3 binding sites in the cell nuclei to revelation of T3 receptors as T3-inducible transcription factors in relation to T3 action at cellular level. It also focuses on milestones of investigation, comprising RXR/TR dimerization, cross-talk between T3 receptors, and other regulatory pathways within the cell and mainly on genomic action of T3. This review also focuses on novel directions of investigation on relationships between T3 receptors and cancer. Based on the update of available literature and the author's experimental experience, it is devoted to clinicians and medical students.
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Herwig A, Campbell G, Mayer CD, Boelen A, Anderson RA, Ross AW, Mercer JG, Barrett P. A thyroid hormone challenge in hypothyroid rats identifies T3 regulated genes in the hypothalamus and in models with altered energy balance and glucose homeostasis. Thyroid 2014; 24:1575-93. [PMID: 25087834 PMCID: PMC4229697 DOI: 10.1089/thy.2014.0169] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND The thyroid hormone triiodothyronine (T3) is known to affect energy balance. Recent evidence points to an action of T3 in the hypothalamus, a key area of the brain involved in energy homeostasis, but the components and mechanisms are far from understood. The aim of this study was to identify components in the hypothalamus that may be involved in the action of T3 on energy balance regulatory mechanisms. METHODS Sprague Dawley rats were made hypothyroid by giving 0.025% methimazole (MMI) in their drinking water for 22 days. On day 21, half the MMI-treated rats received a saline injection, whereas the others were injected with T3. Food intake and body weight measurements were taken daily. Body composition was determined by magnetic resonance imaging, gene expression was analyzed by in situ hybridization, and T3-induced gene expression was determined by microarray analysis of MMI-treated compared to MMI-T3-injected hypothalamic RNA. RESULTS Post mortem serum thyroid hormone levels showed that MMI treatment decreased circulating thyroid hormones and increased thyrotropin (TSH). MMI treatment decreased food intake and body weight. Body composition analysis revealed reduced lean and fat mass in thyroidectomized rats from day 14 of the experiment. MMI treatment caused a decrease in circulating triglyceride concentrations, an increase in nonesterified fatty acids, and decreased insulin levels. A glucose tolerance test showed impaired glucose clearance in the thyroidectomized animals. In the brain, in situ hybridization revealed marked changes in gene expression, including genes such as Mct8, a thyroid hormone transporter, and Agrp, a key component in energy balance regulation. Microarray analysis revealed 110 genes to be up- or downregulated with T3 treatment (± 1.3-fold change, p<0.05). Three genes chosen from the differentially expressed genes were verified by in situ hybridization to be activated by T3 in cells located at or close to the hypothalamic ventricular ependymal layer and differentially expressed in animal models of long- and short-term body weight regulation. CONCLUSION This study identified genes regulated by T3 in the hypothalamus, a key area of the brain involved in homeostasis and neuroendocrine functions. These include genes hitherto not known to be regulated by thyroid status.
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Affiliation(s)
- Annika Herwig
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
- Zoological Institute, University of Hamburg, Hamburg, Germany
| | - Gill Campbell
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Claus-Dieter Mayer
- Biomathematics and Statistics Scotland, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Anita Boelen
- Department of Endocrinology, Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Richard A. Anderson
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Alexander W. Ross
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Julian G. Mercer
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Perry Barrett
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
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Abstract
Thyroid hormone has been known for decades as a hormone with profound effects on energy expenditure and ability to control weight. The regulation of energy expenditure by thyroid hormone primarily occurs via regulation of the activity, or expression, of uncoupling proteins in peripheral tissues. However, mechanistically this requires a signal from the brain to change circulating levels of thyroxine and thyroid hormone or increased sympathetic drive to peripheral tissues to alter local thyroid hormone levels via increased expression of type 2 deiodinase. However, little consideration has been given to the potential role and involvement of thyroid hormones action in the brain in the regulation of energy balance. Recent evidence implicates thyroid hormone as a shortterm signal of energy deficit imposed by starvation. Furthermore, thyroid hormone action within the hypothalamus is involved in adjusting long-term energy expenditure in seasonal animals which endure food shortages in winter. Evidence from several studies suggests that regulation of type 2 and type 3 deiodinase enzymes in tanycytes of the third ventricle are gatekeepers of thyroid hormone levels in the hypothalamus. This paper reviews some of the evidence for the role of deiodinase enzymes and the actions of thyroid hormone in the hypothalamus in the regulation of energy balance.
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Affiliation(s)
| | | | | | | | - Perry Barrett
- *Dr Perry Barrett, Rowett Research Institute, Greenburn Road, Buckburn, Aberdeen AB21 9SB, UK, Tel +44 1224 7166–60, Fax -53, E-mail
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WANG KM, BENMILOUD M. EFFECT OF THYROXINE AND THIOURACIL ON THE MG++-ACTIVATED ATPASE ON THE RAT MYOCARDIUM. Life Sci 1996; 3:431-40. [PMID: 14198484 DOI: 10.1016/0024-3205(64)90203-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hashizume K, Ichikawa K. Localization of 3,5,3'-L-triiodothyronine receptor in rat kidney mitochondrial membranes. Biochem Biophys Res Commun 1982; 106:920-6. [PMID: 6288037 DOI: 10.1016/0006-291x(82)91798-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Michelot J, Dastugue B, Defer N, Meyniel G. In vitro triiodothyronine binding to cytoplasmic proteins from human red blood cells. Biochem Biophys Res Commun 1979; 88:1368-74. [PMID: 475787 DOI: 10.1016/0006-291x(79)91131-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Sterling K, Lazarus JH, Milch PO, Sakurada T, Brenner MA. Mitochondrial thyroid hormone receptor: localization and physiological significance. Science 1978; 201:1126-9. [PMID: 210507 DOI: 10.1126/science.210507] [Citation(s) in RCA: 86] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Binding studies of thyroid hormone to submitochondrial fractions from rat liver suggest that the component responsible for high-affinity, low-capacity (saturable) binding of hormones arises from the inner mitochondrial membrane. The partially purified component, approximately 150,000 daltons, appears to be half protein and half lipid, largely phospholipids, tentatively identified as lecithin, phosphatidyl ethanolamine, and cardiolipin. A similar hormone-binding macromolecule was found in mitochondria from rabbit kidney, from human liver and kidney, and from rat kidney, myocardium, skeletal muscle, intestinal mucosa, whole small intestine, adipose tissue, and lung. It was absent from mitochondria of adult rat brain, spleen, and testis, organs calorigenically unresponsive to thyroid hormones injected in vivo, but was present in mitochondria from brains of rats 12 days old and younger. The organ distribution of the hormone-binding protein and its presence in neonatal brain mitochondria supports the biological relevance of the mitochondrial component as a thyroid hormone receptor.
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Höffken B, Ködding R, Von Zur Mühlen A, Hehrmann T, Jüppner H, Hesch RD. Regulation of thyroid hormone metabolism in rat liver fractions. Biochim Biophys Acta Gen Subj 1978; 539:114-24. [PMID: 23865 DOI: 10.1016/0304-4165(78)90126-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The nature of the conversion of thyroxine (T4) to triiodothyronine (T3) and reverse triiodothyronine (rT3) was investigated in rat liver homogenate and microsomes. A 6-fold rise of T3 and 2.5-fold rise of rT3 levels determined by specific radioimmunoassays was observed over 6 h after the addition of T4. An enzymic process is suggested that converts T4 to T3 and rT3. For T3 the optimal pH is 6 and for rT3, 9.5. The converting activity for both T3 and rT3 is temperature dependent and can be suppressed by heat, H2O2, merthiolate and by 5-propyl-2-thiouracil. rT3 and to a lesser degree iodide, were able to inhibit the production of T3 in a dose related fashion. Therefore the pH dependency, rT3 and iodide may regulate the availability of T3 or rT3 depending on the metabolic requirements of thyroid hormones.
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Schwartz HL, Oppenheimer JH. Physiologic and biochemical actions of thyroid hormone. PHARMACOLOGY & THERAPEUTICS. PART B: GENERAL & SYSTEMATIC PHARMACOLOGY 1978; 3:349-76. [PMID: 203955 DOI: 10.1016/s0306-039x(78)80002-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Abstract
The subcellular compartments have been investigated to compare proteins capable of binding triiodothyronine and thyroxine; specific binders have been found in cytosol, nuclei, and mitochondria from rat liver and kidney. The binding protein from the inner mitochondrial membrane had the highest association constant (greater than 10(11) liters per mole), suggesting possible direct hormone action on the mitochondria. Binding of hormone analogs was found to be related to known physiological potency, and stereospecific discrimination between L- and D-thyroxine was observed. The saturable receptor was found in the mitochondrial membranes of rat liver, kidney, myocardium, and skeletal muscle but not in mitochondria from the unresponsive tissues: brain, spleen, and testis. Oxidative phosphorylation by mitochondrial vesicles from hypothyroid rats increased after the addition of physiological concentrations of triiodothyronine, which corroborated direct hormone action on mitochondria.
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Singh SP, Carter AC, Kydd DM, Costanzo RR. Interaction between thyroid hormones and erythrocyte membranes: competitive inhibition of binding 131 I-L-triiodothyronine and 131 I-L-thyroxine by their analogs. ENDOCRINE RESEARCH COMMUNICATIONS 1976; 3:119-31. [PMID: 182449 DOI: 10.3109/07435807609052927] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Molecular structural characteristics of thyroid hormones which influence binding to the erythrocyte membranes were investigated by competitive binding experiments. The ability of thyroid hormone analogs to displace 131 I-L-thyroxine and 131 I-L-triiodothyronine from the membranes was considered evidence of their competitive binding. The diphenyl ether linkage (thyronine) was essential as compounds with a single aromatic ring were weakly competitive. The presence of three iodine atoms at 3, 5 and 3' positions on thyronine was optimal for maximal competitive binding. There was weak competitive binding of analogs if chlorine or bromine was substituted for iodine. The alanine side chain was required for optimal binding as N-acetyl-l-thyroxine and various deaminated analogs were poor competitors compared to T4 and T3. L-isomers of T4 and T3 showed greater competitive binding to erythrocyte membranes than the corresponding d-isomers.
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Abstract
The presence of "high-affinity-saturable" binding sites for thyroid hormones of similar characteristics not only in isolated nuclei but in all the major extranuclear cellular components, as well as the failure of cytosol to promote nuclear binding, invalidates the analogy with steroid hormone receptors and necessitates a more critical assessment of the physiological relevance of current approaches to binding of thyroid hormone in vitro nuclear preparations.
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Ecdysonbindende Proteinfraktionen in den Speicheldr�sen von Drosophila hydei. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1970. [DOI: 10.1007/bf00297737] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Emmerich H. [Concentration of tritium-labelled ecdysone in the cell nuclei of the salivary glands of Drosophila hydei]. Exp Cell Res 1969; 58:261-70. [PMID: 5404075 DOI: 10.1016/0014-4827(69)90504-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Weinbach EC, Garbus J. Mechanism of action of reagents that uncouple oxidative phosphorylation. Nature 1969; 221:1016-8. [PMID: 4180173 DOI: 10.1038/2211016a0] [Citation(s) in RCA: 190] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Oppenheimer JH, Surks MI, Schwartz HL. The metabolic significance of exchangeable cellular thyroxine. RECENT PROGRESS IN HORMONE RESEARCH 1969; 25:381-422. [PMID: 4981897 DOI: 10.1016/b978-0-12-571125-8.50011-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Arcos JC, Stacey RE, Mathison JB, Argus MF. Kinetic parameters of mitochondrial swelling. Effect of animal age. Tissue distribution of the mitochondrial "contractile protein". Exp Cell Res 1967; 48:448-60. [PMID: 6082322 DOI: 10.1016/0014-4827(67)90368-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Oppenheimer JH, Bernstein G, Hasen J. Estimation of rapidly exchangeable cellular thyroxine from the plasma disappearance curves of simultaneously administered thyroxine-131-I and albumin-125-I. J Clin Invest 1967; 46:762-77. [PMID: 4960936 PMCID: PMC297079 DOI: 10.1172/jci105577] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
A mathematical analysis of the plasma disappearance curves of simultaneously injected thyroxine-(131)I and albumin-(125)I allows the development of simple formulas for estimating the pool size and transfer kinetics of rapidly exchangeable intracellular thyroxine in man. Evidence is presented that the early distribution kinetics of albumin-(125)I can be used to represent the expansion of the thyroxine-(131)I-plasma protein complex into the extracellular compartment. Calculations indicate that approximately 37% of total body extrathyroidal thyroxine is within such exchangeable tissue stores. The average cellular clearance of thyroxine is 42.7 ml per minute, a value far in excess of the metabolic clearance of this hormone. Results of external measurements over the hepatic area and studies involving hepatic biopsies indicate that the liver is an important but probably not the exclusive component of the intracellular compartment. The partition of thyroxine between cellular and extracellular compartments is determined by the balance of tissue and plasma protein binding factors. The fractional transfer constants are inversely related to the strength of binding of each compartment and directly proportional to the permeability characteristic of the hypothetical membrane separating compartments. Appropriate numerical values for these factors are assigned. An increased fractional entrance of thyroxine-(131)I into the cellular compartment was noted in a patient with congenital decrease in the maximal binding capacity of thyroxine-binding globulin and in three patients after the infusion of 5,5-diphenylhydantoin. Decreased intracellular space and impaired permeability characteristics were observed in five patients with hepatic disease. Studies of the rate of entrance of thyroxine-(131)I and albumin-(125)I into the pleural effusion of a patient with congestive heart failure suggested that transcapillary passage of thyroxine independent of its binding protein is not a predominant factor in the total distribution kinetics of thyroxine-(131)I. The thesis is advanced that the distribution of thyroxine, both within the extracellular compartment and between the extracellular and intracellular compartments, is accomplished largely by the carrier protein and the direct transfer of thyroxine from one binding site to another. The concept of free thyroxine is reassessed in terms of this formulation.
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Abstract
Both actinomycin D and puromycin suppress the formation of colonies by cultured human kidney epithelial cells (T-l), but inactivation by puromycin is partially reversed with thyroid hormones. Uptake by the cells of L-thyroxine labeled with iodine-125, 60 to 80 percent of which is nuclear, is depressed by actinomycin and enhanced by puromycin. Genome and possibly nuclear membrane are implicated as initiating loci.
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Weinbach EC, Garbus J. The Interaction of Uncoupling Phenols with Mitochondria and with Mitochondrial Protein. J Biol Chem 1965. [DOI: 10.1016/s0021-9258(18)97510-1] [Citation(s) in RCA: 123] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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TATA JR, ERNSTER L, SURANYI EM. Interaction between thyroid hormones and cellular constituents. BIOCHIMICA ET BIOPHYSICA ACTA 1962; 60:480-91. [PMID: 13919772 DOI: 10.1016/0006-3002(62)90867-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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