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Ricci C, Kakularam KR, Marzocchi C, Capecchi G, Riolo G, Boschin F, Kuhn H, Castagna MG, Cantara S. Thr92Ala polymorphism in the type 2 deiodinase gene: an evolutionary perspective. J Endocrinol Invest 2020; 43:1749-1757. [PMID: 32436183 DOI: 10.1007/s40618-020-01287-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/30/2020] [Indexed: 12/20/2022]
Abstract
PURPOSE In the past, a role of thyroid hormones in human evolution has been hypothesized. T3, the metabolically active form, derives from extrathyroidal conversion of T4 by deionidase 2 (D2) enzyme encoded by DIO2 gene. In thyroid-deficient patients, decreased levels of free T3 have been associated with the polymorphism rs225014 A/G in DIO2, which causes the substitution of Threonine with Alanine (p.Thr92Ala) at protein level. METHODS We compared DNA and protein sequences of D2 from archaic human subspecies with those of contemporary humans. RESULTS Neanderthals and Denisovans displayed only the G allele at the rs225014 polymorphism, which encodes for an Alanine on the amino acid level. These data suggest that these hominines were homozygous for the Ala amino acid. These arcaic humans often lived in condition of iodine deficiency and thus, defective mechanisms of T3 biosynthesis could be life threatining. A reduced D2 activity is likely to cause decreased T3 levels, which could be critical for those individuals. Neanderthals and Denisovans were hunters/gatherers, and their diet was mainly based on the consumption of meat, with a low intake of carbohydrates. The need for circulating T3 is reduced at such alimentary conditions. On the basis of our genome comparisons the A allele, corresponding to Threonine and associated with higher levels of circulating T3 in thyroid-deficient patients, appeared for the first time during evolution in Anatomically Modern Humans during the Upper Pleistocene and has been conserved during the Neolithic age. With the advent of agriculture and herding, individuals carrying A allele might have a higher probability for surviving and reproducing. Thus, the variant was positively selected during the evolution. CONCLUSION Here we present an evolutionary perspective for p.Thr92Ala variant of D2 from Neanderthals to Anatomically Modern Humans.
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Affiliation(s)
- C Ricci
- Department of Medical, Surgical and Neurological Sciences, University of Siena, Viale Bracci 16, 53100, Siena, Italy
| | - K R Kakularam
- Corporate Member of Freie Universität Berlin, Humboldt-Universität Zu Berlin, and Berlin Institute of Health, Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - C Marzocchi
- Department of Medical, Surgical and Neurological Sciences, University of Siena, Viale Bracci 16, 53100, Siena, Italy
| | - G Capecchi
- Department of Physical Sciences, Earth and Environment, University of Siena, Siena, Italy
| | - G Riolo
- Department of Medical, Surgical and Neurological Sciences, University of Siena, Viale Bracci 16, 53100, Siena, Italy
| | - F Boschin
- Department of Physical Sciences, Earth and Environment, University of Siena, Siena, Italy
| | - H Kuhn
- Corporate Member of Freie Universität Berlin, Humboldt-Universität Zu Berlin, and Berlin Institute of Health, Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - M G Castagna
- Department of Medical, Surgical and Neurological Sciences, University of Siena, Viale Bracci 16, 53100, Siena, Italy
| | - S Cantara
- Department of Medical, Surgical and Neurological Sciences, University of Siena, Viale Bracci 16, 53100, Siena, Italy.
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Lacámara N, Lecumberri B, Barquiel B, Escribano A, González-Casado I, Álvarez-Escolá C, Aleixandre-Blanquer F, Morales F, Alfayate R, Bernal-Soriano MC, Miralles R, Yildirim Simsir I, Özgen AG, Bernal J, Berbel P, Moreno JC. Identification of Resistance to Exogenous Thyroxine in Humans. Thyroid 2020; 30:1732-1744. [PMID: 32498666 DOI: 10.1089/thy.2019.0825] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Background: Thyroxine (T4) to triiodothyronine (T3) deiodination in the hypothalamus/pituitary is mediated by deiodinase type-2 (D2) activity. Dio2(-/-) mice show central resistance to exogenous T4. Patients with resistance to exogenous thyroxine (RETH) have not been described. The aim of this study was to identify hypothyroid patients with thyrotropin (TSH) unresponsiveness to levothyroxine (LT4) and to characterize the clinical, hormonal, and genetic features of human RETH. Methods: We investigated hypothyroid patients with elevated TSH under LT4 treatment at doses leading to clinical and/or biochemical hyperthyroidism. TSH and free T4 (fT4) were determined by chemiluminescence, and total T4, T3, and reverse T3 (rT3) by radioimmunoassay. TSH/fT4 ratio at inclusion and T3/T4, rT3/T4, and T3/rT3 ratios at follow-up were compared with those from patients with resistance to thyroid hormone (RTH) due to thyroid hormone receptor-β (THRB) mutations. DIO2, including the Ala92-D2 polymorphism, selenocysteine binding protein 2 (SECISBP2), and THRB were fully sequenced. Results: Eighteen hypothyroid patients (nine of each sex, 3-59 years) treated with LT4 showed elevated TSH (15.5 ± 4.7 mU/L; reference range [RR]: 0.4-4.5), fT4 (20.8 ± 2.4 pM; RR: 9-20.6), and TSH/fT4 ratio (0.74 ± 0.25; RR: 0.03-0.13). Despite increasing LT4 doses from 1.7 ± 1.0 to 2.4 ± 1.7 μg/kg/day, TSH remained elevated (6.9 ± 2.7 mU/L). Due to hyperthyroid symptoms, LT4 doses were reduced, and TSH increased again to 7.9 ± 3.2 mU/L. In the euthyroid/hyperthyrotropinemic state, T3/T4 and T3/rT3 ratios were decreased (9.2 ± 2.4, RR: 11.3-15.3 and 2.5 ± 1.4, RR: 7.5-8.5, respectively) whereas rT3/T4 was increased (0.6 ± 0.2; RR: 0.43-0.49), suggesting reduced T4 to T3 and increased T4 to rT3 conversion. These ratios were serum T4-independent and were not observed in RTH patients. Genetic testing was normal. The Ala92-D2 polymorphism was present in 7 of 18 patients, but the allele dose did not correlate with RETH. Conclusions: Human RETH is characterized by iatrogenic thyrotoxicosis and elevated TSH/fT4 ratio. In the euthyroid/hyperthyrotropinemic state, it is confirmed by decreased T3/T4 and T3/rT3 ratios, and elevated rT3/T4 ratio. This phenotype may guide clinicians to consider combined T4+T3 therapy in a targeted fashion. The absence of germline DIO2 mutations suggests that aberrant post-translational D2 modifications in pituitary/hypothalamus or defects in other genes regulating the T4 to T3 conversion pathway could be involved in RETH.
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Affiliation(s)
- Nerea Lacámara
- Thyroid Molecular Laboratory, Institute for Medical and Molecular Genetics (INGEMM), La Paz University Hospital, Autonomous University of Madrid, Madrid, Spain
- The Rare Diseases Networking Biomedical Research Centre (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | | | - Beatriz Barquiel
- Department of Endocrinology, La Paz University Hospital, Madrid, Spain
| | - Arancha Escribano
- Department of Pediatric Endocrinology, Virgen de la Arrixaca University Hospital, Murcia, Spain
| | | | | | | | - Francisco Morales
- Department of Endocrinology, Virgen Del Rocío University Hospital, Sevilla, Spain
| | - Rocío Alfayate
- Clinical Chemistry Department, Alicante University Hospital, Alicante, Spain
| | | | - Raquel Miralles
- Department of Endocrinology, Alicante University Hospital, Alicante, Spain
| | - Ilgin Yildirim Simsir
- Department of Endocrinology and Metabolism Disorders, Ege University Medical Faculty, Izmir, Turkey
| | - Ahmet Gökhan Özgen
- Department of Endocrinology and Metabolism Disorders, Ege University Medical Faculty, Izmir, Turkey
| | - Juan Bernal
- Department of Endocrine and Nervous System, Instituto de Investigaciones Biomédicas, CSIC, and CIBERER Instituto de Salud Carlos III, Madrid, Spain
| | - Pere Berbel
- Department of Histology and Anatomy, Faculty of Medicine, Universidad Miguel Hernández de Elche, Alicante, Spain
| | - Jose Carlos Moreno
- Thyroid Molecular Laboratory, Institute for Medical and Molecular Genetics (INGEMM), La Paz University Hospital, Autonomous University of Madrid, Madrid, Spain
- The Rare Diseases Networking Biomedical Research Centre (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
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Razvi S, Mrabeti S, Luster M. Managing symptoms in hypothyroid patients on adequate levothyroxine: a narrative review. Endocr Connect 2020; 9:R241-R250. [PMID: 33112818 PMCID: PMC7774765 DOI: 10.1530/ec-20-0205] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/05/2020] [Indexed: 12/20/2022]
Abstract
The current standard of care for hypothyroidism is levothyroxine (LT4) monotherapy to reduce levels of thyrotropin (thyroid-stimulating hormone, TSH) within its reference range and amelioration of any symptoms. A substantial minority continues to report hypothyroid-like symptoms despite optimized TSH, however. These symptoms are not specific to thyroid dysfunction and are frequent among the euthyroid population, creating a therapeutic dilemma for the treating clinician as well as the patient. We present a concise, narrative review of the clinical research and evidence-based guidance on the management of this challenging population. The clinician may endeavor to ensure that the serum TSH is within the target range. However, the symptomatic patient may turn to alternative non-evidence-based therapies in the hope of obtaining relief. Accordingly, it is important for the clinician to check for conditions unrelated to the thyroid that could account for the ongoing symptoms such as other autoimmune conditions, anemia or mental health disorders. Systematic and thorough investigation of the potential causes of persistent symptoms while receiving LT4 therapy will resolve the problem for most patients. There may be some patients that may benefit from additional treatment with liothyronine (LT3), although it is unclear as yet as to which patient group may benefit the most from combined LT4 + LT3 therapy. In the future, personalized treatment with LT4 + LT3 may be of benefit for some patients with persistent symptoms of hypothyroidism such as those with polymorphisms in the deiodinase enzyme 2 (DIO2). For now, this remains a subject for research.
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Affiliation(s)
- Salman Razvi
- Translational and Clinical Research Institute, University of Newcastle, Newcastle-upon-Tyne, UK
- Correspondence should be addressed to S Razvi:
| | - Sanaa Mrabeti
- Medical Affairs EMEA, Merck Serono Middle East FZ-LLC, Dubai, United Arab Emirates
| | - Markus Luster
- Department of Nuclear Medicine, University Hospital Marburg, Marburg, Germany
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Santesmasses D, Mariotti M, Gladyshev VN. Tolerance to Selenoprotein Loss Differs between Human and Mouse. Mol Biol Evol 2020; 37:341-354. [PMID: 31560400 PMCID: PMC6993852 DOI: 10.1093/molbev/msz218] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mouse has emerged as the most common model organism in biomedicine. Here, we analyzed the tolerance to the loss-of-function (LoF) of selenoprotein genes, estimated from mouse knockouts and the frequency of LoF variants in humans. We found not only a general correspondence in tolerance (e.g., GPX1, GPX2) and intolerance (TXNRD1, SELENOT) to gene LoF between humans and mice but also important differences. Notably, humans are intolerant to the loss of iodothyronine deiodinases, whereas their deletion in mice leads to mild phenotypes, and this is consistent with phenotype differences in selenocysteine machinery loss between these species. In contrast, loss of TXNRD2 and GPX4 is lethal in mice but may be tolerated in humans. We further identified the first human SELENOP variants coding for proteins varying in selenocysteine content. Finally, our analyses suggested that premature termination codons in selenoprotein genes trigger nonsense-mediated decay, but do this inefficiently when UGA codon is gained. Overall, our study highlights differences in the physiological importance of selenoproteins between human and mouse.
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Affiliation(s)
- Didac Santesmasses
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Marco Mariotti
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
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Giannocco G, Kizys MML, Maciel RM, de Souza JS. Thyroid hormone, gene expression, and Central Nervous System: Where we are. Semin Cell Dev Biol 2020; 114:47-56. [PMID: 32980238 DOI: 10.1016/j.semcdb.2020.09.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 09/09/2020] [Accepted: 09/14/2020] [Indexed: 12/27/2022]
Abstract
Thyroid hormones (TH; T3 and T4) play a fundamental role in the fetal stage to the adult phase, controlling gene and protein expression in virtually all tissues. The endocrine and CNS systems have relevant interaction, and the TH are pivotal for the proper functioning of the CNS. A slight failure to regulate TH availability during pregnancy and/or childhood can lead to neurological disorders, for example, autism and cognitive impairment, or depression. In this review, we highlight how TH acts in controlling gene expression, its role in the CNS, and what substances widely found in the environment can cause in this tissue. We highlight the role of Endocrine Disruptors used on an everyday basis in the processing of mRNAs responsible for neurodevelopment. We conclude that TH, more precisely T3, acts mainly throughout its nuclear receptors, that the deficiency of this hormone, either due to the lack of its main substrate iodine, or by to incorrect organification of T4 and T3 in the gland, or by a mutation in transporters, receptors and deiodinases may cause mild (dysregulated mood in adulthood) to severe neurological impairment (Allan-Herndon-Dudley syndrome, presented as early as childhood); T3 is responsible for the expression of numerous CNS genes related to oxygen transport, growth factors, myelination, cell maturation. Substances present in the environment and widely used can interfere with the functioning of the thyroid gland, the action of TH, and the functioning of the CNS.
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Affiliation(s)
- Gisele Giannocco
- Departamento de Medicina, Laboratório de Endocrinologia e Medicina Translacional, Universidade Federal de São Paulo, UNIFESP/EPM, Rua Pedro de Toledo, 669 - 11 andar, São Paulo, SP 04039-032, Brazil; Departamento de Ciências Biológicas, Universidade Federal de São Paulo, UNIFESP, Diadema, SP 09920-000, Brazil
| | - Marina Malta Letro Kizys
- Departamento de Medicina, Laboratório de Endocrinologia e Medicina Translacional, Universidade Federal de São Paulo, UNIFESP/EPM, Rua Pedro de Toledo, 669 - 11 andar, São Paulo, SP 04039-032, Brazil
| | - Rui Monteiro Maciel
- Departamento de Medicina, Laboratório de Endocrinologia e Medicina Translacional, Universidade Federal de São Paulo, UNIFESP/EPM, Rua Pedro de Toledo, 669 - 11 andar, São Paulo, SP 04039-032, Brazil
| | - Janaina Sena de Souza
- Departamento de Medicina, Laboratório de Endocrinologia e Medicina Translacional, Universidade Federal de São Paulo, UNIFESP/EPM, Rua Pedro de Toledo, 669 - 11 andar, São Paulo, SP 04039-032, Brazil; Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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56
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Uter JC, Krämer UM, Schöls L, Rodriguez-Fornells A, Göbel A, Heldmann M, Lichtner P, Brabant G, Münte TF. Single Nucleotide Polymorphisms in Thyroid Hormone Transporter Genes MCT8, MCT10 and Deiodinase DIO2 Contribute to Inter-Individual Variance of Executive Functions and Personality Traits. Exp Clin Endocrinol Diabetes 2020; 128:573-581. [PMID: 31820424 DOI: 10.1055/a-1065-1786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Thyroid hormones are modulators of cognitive functions, and changes in hormone levels affect intelligence, memory, attention and executive function. Single nucleotide polymorphisms (SNPs) of transporter proteins MCT8, MCT10 and deiodinase 2 (DIO2) influence thyroid metabolism and could therefore contribute to inter-individual variance of cognitive functions. This study investigates the influence of these SNPs using an extensive neuropsychological test battery. 656 healthy participants aged 18-39 years were genotyped for four SNPs: MCT8 (rs5937843 and rs6647476), MCT10 (rs14399) and DIO2 (rs225014) and underwent eleven different neuropsychological tests as well as four personality questionnaires. Test results were compared between homo- and heterozygous carriers and for the X-linked MCT8 additionally between men and women. Personality questionnaires revealed that Risk Seeking was reduced in homozygous T carriers and highest in homozygous C carriers of the DIO2 SNP and that both polymorphisms of MCT8 had an additive effect on Physical Aggression in men. Neuropsychological testing indicated that MCT10 affects nonverbal reasoning abilities, DIO2 influences working memory and verbal fluency and MCT8 influences attention, alertness and planning. This pilot study suggests an influence of polymorphisms in thyroid hormone transporter genes and deiodinase on cognitive domains and personality traits.
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Affiliation(s)
| | - Ulrike M Krämer
- Department of Neurology, University of Lübeck, Lübeck, Germany
- Institute of Psychology II, University of Lübeck, Lübeck, Germany
| | - Ludger Schöls
- Department of Neurology and Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Antoni Rodriguez-Fornells
- Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute, Barcelona, Spain
- Department of Cognition, Development and Educational Psychology, University of Barcelona, Barcelona, Spain
- Department of Internal Medicine I, University of Lübeck, Lübeck, Germany
| | - Anna Göbel
- Department of Neurology, University of Lübeck, Lübeck, Germany
| | - Marcus Heldmann
- Department of Neurology, University of Lübeck, Lübeck, Germany
- Institute of Psychology II, University of Lübeck, Lübeck, Germany
| | - Peter Lichtner
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Georg Brabant
- Department of Internal Medicine I, University of Lübeck, Lübeck, Germany
| | - Thomas F Münte
- Department of Neurology, University of Lübeck, Lübeck, Germany
- Institute of Psychology II, University of Lübeck, Lübeck, Germany
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Kang YE, Kang YM, Park B, Shong M, Yi HS. Type 2 deiodinase Thr92Ala polymorphism is associated with a reduction in bone mineral density: A community-based korean genome and epidemiology study. Clin Endocrinol (Oxf) 2020; 93:238-247. [PMID: 32324283 DOI: 10.1111/cen.14206] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/09/2020] [Accepted: 04/20/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Type 2 deiodinase (DIO2)-mediated thyroid hormone synthesis stimulates osteoblast activity and increases the expression of osteoblast differentiation markers, but there are no large cohort studies to identify the role of the DIO2 polymorphism in bone mineral density in humans. METHODS To investigate the hypothesis that individuals with the DIO2 gene polymorphism are susceptible to osteoporosis, we assessed the polymorphism of the DIO2 gene in 7,524 Koreans drawn from the large-scale Ansan-Anseong cohort of the Korean Genome and Epidemiology Study. All of the participants underwent genotyping of the DIO2 Thr92Ala polymorphism (rs225014). RESULTS A total of 6,022 participants were recruited; 1991 (33.0%) were homozygous for the Thr allele, 2,967 (49.3%) were heterozygous (Thr/Ala), and 1064 (17.7%) were homozygous for the Ala allele. The effects of the DIO2 Thr92Ala polymorphism on axial speed of sound (SOS) and the T-score in the tibia and radius were assessed, with age, gender, oestrogen status, body mass index (BMI), serum calcium, 25-hydroxyvitamin D, and parathyroid hormone (PTH) included as covariables. Female subjects carrying the DIO2 Thr92Ala polymorphism had significantly lower SOS and T-scores than control participants. Cox regression analysis revealed a significant relationship between the DIO2 polymorphism and diagnosis of osteoporosis in female participants. CONCLUSION DIO2 Thr92Ala polymorphism is associated with decreased SOS and T-scores in the tibia of female subjects independent of other clinical parameters, where this indicates a potential functional role of DIO2 in the maintenance of bone mineral density.
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Affiliation(s)
- Yea Eun Kang
- Research Center for Endocrine and Metabolic Diseases, Chungnam National University School of Medicine, Daejeon, Korea
| | - Young Mi Kang
- Research Center for Endocrine and Metabolic Diseases, Chungnam National University School of Medicine, Daejeon, Korea
| | - Boyoung Park
- Department of Medicine, College of Medicine, Hanyang University, Seoul, Korea
| | - Minho Shong
- Research Center for Endocrine and Metabolic Diseases, Chungnam National University School of Medicine, Daejeon, Korea
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Korea
| | - Hyon-Seung Yi
- Research Center for Endocrine and Metabolic Diseases, Chungnam National University School of Medicine, Daejeon, Korea
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Korea
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Ettleson MD, Bianco AC. Individualized Therapy for Hypothyroidism: Is T4 Enough for Everyone? J Clin Endocrinol Metab 2020; 105:dgaa430. [PMID: 32614450 PMCID: PMC7382053 DOI: 10.1210/clinem/dgaa430] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/29/2020] [Indexed: 02/07/2023]
Abstract
CONTEXT It is well recognized that some hypothyroid patients on levothyroxine (LT4) remain symptomatic, but why patients are susceptible to this condition, why symptoms persist, and what is the role of combination therapy with LT4 and liothyronine (LT3), are questions that remain unclear. Here we explore evidence of abnormal thyroid hormone (TH) metabolism in LT4-treated patients, and offer a rationale for why some patients perceive LT4 therapy as a failure. EVIDENCE ACQUISITION This review is based on a collection of primary and review literature gathered from a PubMed search of "hypothyroidism," "levothyroxine," "liothyronine," and "desiccated thyroid extract," among other keywords. PubMed searches were supplemented by Google Scholar and the authors' prior knowledge of the subject. EVIDENCE SYNTHESIS In most LT4-treated patients, normalization of serum thyrotropin levels results in decreased serum T3/T4 ratio, with relatively lower serum T3 levels; in at least 15% of the cases, serum T3 levels are below normal. These changes can lead to a reduction in TH action, which would explain the slower rate of metabolism and elevated serum cholesterol levels. A small percentage of patients might also experience persistent symptoms of hypothyroidism, with impaired cognition and tiredness. We propose that such patients carry a key clinical factor, for example, specific genetic and/or immunologic makeup, that is well compensated while the thyroid function is normal but might become apparent when compounded with relatively lower serum T3 levels. CONCLUSIONS After excluding other explanations, physicians should openly discuss and consider therapy with LT4 and LT3 with those hypothyroid patients who have persistent symptoms or metabolic abnormalities despite normalization of serum thyrotropin level. New clinical trials focused on symptomatic patients, genetic makeup, and comorbidities, with the statistical power to identify differences between monotherapy and combination therapy, are needed.
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Affiliation(s)
- Matthew D Ettleson
- Section of Adult and Pediatric Endocrinology and Metabolism, University of Chicago, Chicago, Illinois, USA
| | - Antonio C Bianco
- Section of Adult and Pediatric Endocrinology and Metabolism, University of Chicago, Chicago, Illinois, USA
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Porcelli T, Salvatore D. Targeting the right population for T3 + T4 combined therapy: where are we now and where to next? Endocrine 2020; 69:244-248. [PMID: 32572783 DOI: 10.1007/s12020-020-02391-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 06/10/2020] [Indexed: 01/13/2023]
Abstract
The universal applicability of levothyroxine (LT4) monotherapy for the treatment of hypothyroidism has been questioned in recent years. Indeed, it is now clear that about 10-15% of LT4-treated hypothyroid patients are dissatisfied with their treatment. It is plausible that this subset of hypothyroid patients may need T3 + T4 combined therapy to restore peripheral euthyroidism. To address this issue, many clinical trials have investigated the effect of T3 + T4 combinations versus standard LT4-based therapy. However, to date, results have been inconclusive, mainly due to the lack of markers that identify candidates for combination therapy. A breakthrough in this field came with the recent finding that several single-nucleotide polymorphisms in the deiodinase genes are associated with the persistence of hypothyroid symptoms in biochemically euthyroid LT4-treated patients, and are thus markers of candidates for combination therapy. In addition, whole-genome association studies are expanding our knowledge of other genes of the thyroid hormone (TH) pathway that affect serum TH levels. To target the right population for the T3 + T4 combined therapy, the next step is to translate these new findings into prospective trials. Hopefully, this will pave the way to personalized therapy for each hypothyroid patient.
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Affiliation(s)
- Tommaso Porcelli
- Department of Public Health, University of Naples Federico II, Naples, Italy.
| | - Domenico Salvatore
- Department of Public Health, University of Naples Federico II, Naples, Italy
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Giammanco M, Di Liegro CM, Schiera G, Di Liegro I. Genomic and Non-Genomic Mechanisms of Action of Thyroid Hormones and Their Catabolite 3,5-Diiodo-L-Thyronine in Mammals. Int J Mol Sci 2020; 21:ijms21114140. [PMID: 32532017 PMCID: PMC7312989 DOI: 10.3390/ijms21114140] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 02/06/2023] Open
Abstract
Since the realization that the cellular homologs of a gene found in the retrovirus that contributes to erythroblastosis in birds (v-erbA), i.e. the proto-oncogene c-erbA encodes the nuclear receptors for thyroid hormones (THs), most of the interest for THs focalized on their ability to control gene transcription. It was found, indeed, that, by regulating gene expression in many tissues, these hormones could mediate critical events both in development and in adult organisms. Among their effects, much attention was given to their ability to increase energy expenditure, and they were early proposed as anti-obesity drugs. However, their clinical use has been strongly challenged by the concomitant onset of toxic effects, especially on the heart. Notably, it has been clearly demonstrated that, besides their direct action on transcription (genomic effects), THs also have non-genomic effects, mediated by cell membrane and/or mitochondrial binding sites, and sometimes triggered by their endogenous catabolites. Among these latter molecules, 3,5-diiodo-L-thyronine (3,5-T2) has been attracting increasing interest because some of its metabolic effects are similar to those induced by T3, but it seems to be safer. The main target of 3,5-T2 appears to be the mitochondria, and it has been hypothesized that, by acting mainly on mitochondrial function and oxidative stress, 3,5-T2 might prevent and revert tissue damages and hepatic steatosis induced by a hyper-lipid diet, while concomitantly reducing the circulating levels of low density lipoproteins (LDL) and triglycerides. Besides a summary concerning general metabolism of THs, as well as their genomic and non-genomic effects, herein we will discuss resistance to THs and the possible mechanisms of action of 3,5-T2, also in relation to its possible clinical use as a drug.
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Affiliation(s)
- Marco Giammanco
- Department of Surgical, Oncological and Oral Sciences (Discipline Chirurgiche, Oncologiche e Stomatologiche), University of Palermo, 90127 Palermo, Italy;
| | - Carlo Maria Di Liegro
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF)), University of Palermo, 90128 Palermo, Italy; (C.M.D.L.); (G.S.)
| | - Gabriella Schiera
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF)), University of Palermo, 90128 Palermo, Italy; (C.M.D.L.); (G.S.)
| | - Italia Di Liegro
- Department of Biomedicine, Neurosciences and Advanced Diagnostics (Dipartimento di Biomedicina, Neuroscienze e Diagnostica avanzata (Bi.N.D.)), University of Palermo, 90127 Palermo, Italy
- Correspondence: ; Tel.: +39-091-2389-7415 or +39-091-2389-7446
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Pasternak JA, MacPhee DJ, Harding JCS. Maternal and fetal thyroid dysfunction following porcine reproductive and respiratory syndrome virus2 infection. Vet Res 2020; 51:47. [PMID: 32228691 PMCID: PMC7106657 DOI: 10.1186/s13567-020-00772-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 03/15/2020] [Indexed: 12/20/2022] Open
Abstract
To better understand the host response to porcine reproductive and respiratory virus-2 (PRRSV2) we evaluated circulating thyroid hormone and associated gene expression in a late gestation challenge model. Pregnant gilts were inoculated at gestation day 85 and fetal samples collected at either 12 or 21 days post-infection (dpi). A subset of fetuses was selected for analysis based on viability and viral load categorized as either uninfected-viable (UNIF), high viral load viable (HV-VIA) or high viral load meconium stained (HV-MEC) and were compared with gestational age matched controls (CON). In dams, circulating levels of total T3 and T4 decreased in the acute period following infection and rebounded by 21 dpi. A similar effect was observed in fetuses, but was largely restricted to HV-VIA and HV-MEC, with minimal decrease noted in UNIF relative to CON at 21 dpi. Gene expression in fetal heart at 12 dpi showed significant decompensatory transcription of thyroid hormone transporters (SLC16A2) and deiodinases (DIO2, DIO3), which was not observed in brain. Correspondingly, genes associated with cell cycle progression (CDK1,2,4) were downregulated in only the heart of highly infected fetuses, while expression of their inhibitor (CDKN1A) was upregulated in both tissues. Finally, expression of genes associated with cardiac stress including CAMKD and AGT were upregulated in the hearts of highly infected fetuses, and a shift in expression of MYH6 to MYH7 was observed in HV-MEC fetuses specifically. Collectively, the results suggest PRRSV2 infection causes a hypothyroid state that disproportionally impacts the fetal heart over the brain.
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Affiliation(s)
- J Alex Pasternak
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Dr, Saskatoon, SK, S7N 5B4, Canada. .,Department of Animal Sciences, Purdue University, 270 S. Russell St, West Lafayette, IN, 47907, USA.
| | - Daniel J MacPhee
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Dr, Saskatoon, SK, S7N 5B4, Canada
| | - John C S Harding
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Dr, Saskatoon, SK, S7N 5B4, Canada
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Winther KH, Rayman MP, Bonnema SJ, Hegedüs L. Selenium in thyroid disorders - essential knowledge for clinicians. Nat Rev Endocrinol 2020; 16:165-176. [PMID: 32001830 DOI: 10.1038/s41574-019-0311-6] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/09/2019] [Indexed: 12/14/2022]
Abstract
In the 1990s, selenium was identified as a component of an enzyme that activates thyroid hormone; since this discovery, the relevance of selenium to thyroid health has been widely studied. Selenium, known primarily for the antioxidant properties of selenoenzymes, is obtained mainly from meat, seafood and grains. Intake levels vary across the world owing largely to differences in soil content and factors affecting its bioavailability to plants. Adverse health effects have been observed at both extremes of intake, with a narrow optimum range. Epidemiological studies have linked an increased risk of autoimmune thyroiditis, Graves disease and goitre to low selenium status. Trials of selenium supplementation in patients with chronic autoimmune thyroiditis have generally resulted in reduced thyroid autoantibody titre without apparent improvements in the clinical course of the disease. In Graves disease, selenium supplementation might lead to faster remission of hyperthyroidism and improved quality of life and eye involvement in patients with mild thyroid eye disease. Despite recommendations only extending to patients with Graves ophthalmopathy, selenium supplementation is widely used by clinicians for other thyroid phenotypes. Ongoing and future trials might help identify individuals who can benefit from selenium supplementation, based, for instance, on individual selenium status or genetic profile.
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Affiliation(s)
| | - Margaret Philomena Rayman
- Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Steen Joop Bonnema
- Department of Endocrinology and Metabolism, Odense University Hospital, Odense, Denmark
| | - Laszlo Hegedüs
- Department of Endocrinology and Metabolism, Odense University Hospital, Odense, Denmark.
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Low CSF/serum ratio of free T4 is associated with decreased quality of life in mild hypothyroidism - A pilot study. JOURNAL OF CLINICAL AND TRANSLATIONAL ENDOCRINOLOGY 2020; 19:100218. [PMID: 32154116 PMCID: PMC7052503 DOI: 10.1016/j.jcte.2020.100218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/03/2020] [Accepted: 02/03/2020] [Indexed: 12/14/2022]
Abstract
General health, according to the Likert scale, was considerable affected even in mild hypothyroidism. The level of T4 in the brain, expressed as the CSF/serum f-T4 ratio, was associated with decreased general health. Depressive symptoms, according to the MADRS scale, correlated with the CSF/serum f-T4 ratio. T4 might have a direct effect in the brain, and not only as a storage hormone for the more active T3. Further studies on pharmacokinetics of CSF-thyroxine might be of benefit especially in patients not feeling well.
Background & Objective Patients with mild hypothyroidism often are depressed and have impaired quality of life despite serum free-T4 and T3 within reference values. Therefore, we investigated whether their symptoms were dependent on the concentrations of free -T4 and T3 in the circulation and cerebrospinal fluid (CSF). Methods Twenty-five newly diagnosed, untreated hypothyroid subjects and as many age- and sex-matched healthy controls were investigated. Blood and CSF sampling was performed in the morning after an overnight fast. Quality of life (QoL) was assessed by a Likert scale. In the hypothyroid subjects, the MADRS rating scale was also used to evaluate symptoms of depression. Furthermore, the results obtained by the questionnaires were related to serum and CSF levels of free- T4 and T3 as well as the ratios between them in CSF and in serum. Results Self-reported health was considerably lower in hypothyroid subjects. MADRS was considerably higher than the normal range for healthy individuals. Low CSF/serum free-T4 ratio was correlated with an increased depressed state according to MADRS (p < 0.01), and in addition, CSF/serum free-T4 ratio correlated positively with the self-reported general health Likert scale (p < 0.05). Concentrations of TSH, or free-T3 in serum or CSF, were not associated with an increased depressed state or self-reported general health. Conclusions Low CSF/serum ratio of free-T4 was correlated with impaired general health and mood, in contrast to serum measurements not showing any correlations. These findings might partly explain why some patients with hypothyroidism suffer from mental symptoms, despite adequate serum levels of free-T4. However, the findings need to be confirmed in further and larger studies.
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Key Words
- AHDS, Allan-Herndon-Dudley syndrome
- BBB, blood brain barrier
- BSA, body surface area
- CON, healthy control group in our study
- CRP, C reactive protein
- CSF, cerebrospinal fluid
- DIO2, type II iodothyronine deiodinase-enzyme
- GHLS, General Health Likert Scale
- HYP, hypothyroid subjects in our study
- Hb, hemoglobulin
- M, mean value
- MADRS
- MADRS, Montgomery Asberg Depression Rating Scale
- MCT8, monocarboxylate transporter 8
- Md, median value
- Mild hypothyroidism
- NS, non-significant
- OATP1C1, organic anion transporter polypeptide 1C1
- PH, primary hypothyroidism in general
- Q1, first quartile
- Q3, third quartile
- QoL, quality of life
- Quality of life
- Subclinical hypothyroidism
- T3, triiodothyronine
- T4, thyroxine
- TPO, thyroid peroxidase antibody
- TSH, thyroid stimulating hormone
- Thyroxine
- Triiodothyronine
- f-T3 and f-T4, free unbound thyroid hormone
- s-, serum
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Cheng SY. The Year in Basic Thyroidology. Thyroid 2020; 30:8-12. [PMID: 31822204 PMCID: PMC6983739 DOI: 10.1089/thy.2019.0768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Basic research in 2019 yielded exciting discoveries and advancements in thyroidology. Specifically, there have been breakthroughs in our understanding of the molecular actions of thyroid hormone and thyroid hormone receptors, thyroid hormone metabolism and transport, autoimmunity, and thyroid cancer. Next, I summarize important studies published over the past year and whose major data I presented during the 89th American Thyroid Association annual meeting at the opening plenary session The Year in Thyroidology.
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Affiliation(s)
- Sheue-Yann Cheng
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
- Address correspondence to: Sheue-Yann Cheng, PhD, Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Room 5128, Bethesda, MD 20892-4264
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Tost M, Monreal JA, Armario A, Barbero JD, Cobo J, García-Rizo C, Bioque M, Usall J, Huerta-Ramos E, Soria V, Labad J. Targeting Hormones for Improving Cognition in Major Mood Disorders and Schizophrenia: Thyroid Hormones and Prolactin. Clin Drug Investig 2019; 40:1-14. [DOI: 10.1007/s40261-019-00854-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Abstract
Guidelines on T4 + T3 combination therapy were published in 2012. This review investigates whether the issue is better understood 7 years later. Dissatisfaction with the outcome of T4 monotherapy remains high. Persistent symptoms consist mostly of fatigue, weight gain, problems with memory and thinking and mood disturbances. T4 monotherapy is associated with low serum T3 levels, which often require TSH-suppressive doses of L-T4 for normalization. Peripheral tissue thyroid function tests during T4 treatment indicate mild hyperthyroidism at TSH < 0.03 mU/L and mild hypothyroidism at TSH 0.3-5.0 mU/L; tissues are closest to euthyroidism at TSH 0.03-0.3 mU/L. This is explained by the finding that whereas T4 is usually ubiquinated and targeted for proteasomal degradation, hypothalamic T4 is rather stable and less sensitive to ubiquination. A normal serum TSH consequently does not necessarily indicate a euthyroid state. Persistent symptoms in L-T4 treated patients despite a normal serum TSH remain incompletely understood. One hypothesis is that a SNP (Thr92Ala) in DIO2 (required for local production of T3 out of T4) interferes with its kinetics and/or action, resulting in a local hypothyroid state in the brain. Effective treatment of persistent symptoms has not yet realized. One may try T4 + T3 combination treatment in selected patients as an experimental n = 1 study. The 2012 ETA guidelines are still valid for this purpose. More well-designed randomized clinical trials in selected patients are key in order to make progress. In the meantime the whole issue has become rather complicated by commercial and political overtones, as evident from skyrocketing prices of T3 tablets, aggressive pressure groups and motions in the House of Lords.
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Affiliation(s)
- Wilmar M Wiersinga
- Department of Endocrinology & Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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Duntas LH, Jonklaas J. Levothyroxine Dose Adjustment to Optimise Therapy Throughout a Patient's Lifetime. Adv Ther 2019; 36:30-46. [PMID: 31485977 PMCID: PMC6822824 DOI: 10.1007/s12325-019-01078-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Indexed: 12/12/2022]
Abstract
Levothyroxine is the standard therapy for patients with hypothyroidism, a condition that affects up to 5% of people worldwide. While levothyroxine therapy has substantially improved the lives of millions of hypothyroid patients since its introduction in 1949, the complexity of maintaining biochemical and clinical euthyroidism in patients undergoing treatment with levothyroxine cannot be underestimated. Initial dosing of levothyroxine can vary greatly and may be based on the amount of residual thyroid function retained by the patient, the body weight or lean body mass of the patient, and thyroid-stimulating hormone levels. As levothyroxine is usually administered over a patient’s lifetime, physiological changes throughout life will affect the dose of levothyroxine required to maintain euthyroidism. Furthermore, dose adjustments may need to be made in patients with concomitant medical conditions, in patients taking certain medications, as well as in elderly patients. Patients who have undergone any weight or hormonal changes may require dose adjustments, and the majority of pregnant women require increased doses of levothyroxine. Optimal treatment of hypothyroidism requires a partnership between patient and physician. The physician is tasked with vigilant appraisal of the patient’s status based on a thorough clinical and laboratory assessment and appropriate adjustment of their levothyroxine therapy. The patient in turn is tasked with medication adherence and reporting of symptomatology and any changes in their medical situation. The goal is consistent maintenance of euthyroidism, without the patient experiencing the adverse events and negative health consequences of under- or overtreatment. Funding Merck. Plain Language Summary Plain language summary available for this article.
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Affiliation(s)
- Leonidas H Duntas
- Unit of Endocrinology, Diabetes, and Metabolism, Thyroid Section, Evgenidion Hospital, Athens, Greece.
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Bianco AC, Dumitrescu A, Gereben B, Ribeiro MO, Fonseca TL, Fernandes GW, Bocco BMLC. Paradigms of Dynamic Control of Thyroid Hormone Signaling. Endocr Rev 2019; 40:1000-1047. [PMID: 31033998 PMCID: PMC6596318 DOI: 10.1210/er.2018-00275] [Citation(s) in RCA: 140] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/15/2019] [Indexed: 12/17/2022]
Abstract
Thyroid hormone (TH) molecules enter cells via membrane transporters and, depending on the cell type, can be activated (i.e., T4 to T3 conversion) or inactivated (i.e., T3 to 3,3'-diiodo-l-thyronine or T4 to reverse T3 conversion). These reactions are catalyzed by the deiodinases. The biologically active hormone, T3, eventually binds to intracellular TH receptors (TRs), TRα and TRβ, and initiate TH signaling, that is, regulation of target genes and other metabolic pathways. At least three families of transmembrane transporters, MCT, OATP, and LAT, facilitate the entry of TH into cells, which follow the gradient of free hormone between the extracellular fluid and the cytoplasm. Inactivation or marked downregulation of TH transporters can dampen TH signaling. At the same time, dynamic modifications in the expression or activity of TRs and transcriptional coregulators can affect positively or negatively the intensity of TH signaling. However, the deiodinases are the element that provides greatest amplitude in dynamic control of TH signaling. Cells that express the activating deiodinase DIO2 can rapidly enhance TH signaling due to intracellular buildup of T3. In contrast, TH signaling is dampened in cells that express the inactivating deiodinase DIO3. This explains how THs can regulate pathways in development, metabolism, and growth, despite rather stable levels in the circulation. As a consequence, TH signaling is unique for each cell (tissue or organ), depending on circulating TH levels and on the exclusive blend of transporters, deiodinases, and TRs present in each cell. In this review we explore the key mechanisms underlying customization of TH signaling during development, in health and in disease states.
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Affiliation(s)
- Antonio C Bianco
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
| | - Alexandra Dumitrescu
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
| | - Balázs Gereben
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Miriam O Ribeiro
- Developmental Disorders Program, Center of Biologic Sciences and Health, Mackenzie Presbyterian University, São Paulo, São Paulo, Brazil
| | - Tatiana L Fonseca
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
| | - Gustavo W Fernandes
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
| | - Barbara M L C Bocco
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
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Abstract
The deiodinase family of enzymes mediates the activation and inactivation of thyroid hormone. The role of these enzymes in the regulation of the systemic concentrations of thyroid hormone is well established and underpins the treatment of common thyroid diseases. Interest in this field has increased in the past 10 years as the deiodinases became implicated in tissue development and homeostasis, as well as in the pathogenesis of a wide range of human diseases. Three deiodinases have been identified, namely, types 1, 2 and 3 iodothyronine deiodinases, which differ in their catalytic properties and tissue distribution. Notably, the expression of these enzymes changes during the lifetime of an individual in relation to the different needs of each organ and to ageing. The systemic homeostatic role of deiodinases clearly emerges during changes in serum concentrations of thyroid hormone, as seen in patients with thyroid dysfunction. By contrast, the role of deiodinases at the tissue level allows thyroid hormone signalling to be finely tuned within a given cell in a precise time-space window without perturbing serum concentrations of thyroid hormone. This Review maps the overall functional role of the deiodinases and explores challenges and novel opportunities arising from the expanding knowledge of these 'master' components of the thyroid homeostatic system.
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Affiliation(s)
- Cristina Luongo
- Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy
| | - Monica Dentice
- Department of Clinical Medicine and Surgery, University of Naples "Federico II", Naples, Italy
| | - Domenico Salvatore
- Department of Public Health, University of Naples "Federico II", Naples, Italy.
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Zhao W, Bohleber S, Schmidt H, Seeher S, Howard MT, Braun D, Arndt S, Reuter U, Wende H, Birchmeier C, Fradejas-Villar N, Schweizer U. Ribosome profiling of selenoproteins in vivo reveals consequences of pathogenic Secisbp2 missense mutations. J Biol Chem 2019; 294:14185-14200. [PMID: 31350336 DOI: 10.1074/jbc.ra119.009369] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 07/08/2019] [Indexed: 01/31/2023] Open
Abstract
Recoding of UGA codons as selenocysteine (Sec) codons in selenoproteins depends on a selenocysteine insertion sequence (SECIS) in the 3'-UTR of mRNAs of eukaryotic selenoproteins. SECIS-binding protein 2 (SECISBP2) increases the efficiency of this process. Pathogenic mutations in SECISBP2 reduce selenoprotein expression and lead to phenotypes associated with the reduction of deiodinase activities and selenoprotein N expression in humans. Two functions have been ascribed to SECISBP2: binding of SECIS elements in selenoprotein mRNAs and facilitation of co-translational Sec insertion. To separately probe both functions, we established here two mouse models carrying two pathogenic missense mutations in Secisbp2 previously identified in patients. We found that the C696R substitution in the RNA-binding domain abrogates SECIS binding and does not support selenoprotein translation above the level of a complete Secisbp2 null mutation. The R543Q missense substitution located in the selenocysteine insertion domain resulted in residual activity and caused reduced selenoprotein translation, as demonstrated by ribosomal profiling to determine the impact on UGA recoding in individual selenoproteins. We found, however, that the R543Q variant is thermally unstable in vitro and completely degraded in the mouse liver in vivo, while being partially functional in the brain. The moderate impairment of selenoprotein expression in neurons led to astrogliosis and transcriptional induction of genes associated with immune responses. We conclude that differential SECISBP2 protein stability in individual cell types may dictate clinical phenotypes to a much greater extent than molecular interactions involving a mutated amino acid in SECISBP2.
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Affiliation(s)
- Wenchao Zhao
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Simon Bohleber
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Henrik Schmidt
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Sandra Seeher
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Michael T Howard
- Department of Genetics, University of Utah, Salt Lake City, Utah 84112
| | - Doreen Braun
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Simone Arndt
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Uschi Reuter
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Hagen Wende
- Max Delbrück Center of Molecular Medicine, 13125 Berlin, Germany
| | | | - Noelia Fradejas-Villar
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Ulrich Schweizer
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
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Hernandez A. Thyroid Hormone and Alcoholic Fatty Liver: The Developmental Input. Alcohol Clin Exp Res 2019; 43:1834-1837. [PMID: 31283013 DOI: 10.1111/acer.14145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 06/28/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Arturo Hernandez
- Center for Molecular Medicine, Maine Medical Center Research Institute, Maine Medical Center, Scarborough, Maine.,Graduate School for Biomedical Science and Engineering, University of Maine, Orono, Maine.,Department of Medicine, Tufts University School of Medicine, Boston, Massachusetts
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McAninch EA, Bianco AC. The Swinging Pendulum in Treatment for Hypothyroidism: From (and Toward?) Combination Therapy. Front Endocrinol (Lausanne) 2019; 10:446. [PMID: 31354624 PMCID: PMC6629976 DOI: 10.3389/fendo.2019.00446] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 06/20/2019] [Indexed: 12/26/2022] Open
Abstract
Thyroid hormone replacement for hypothyroidism can be achieved via several approaches utilizing different preparations of thyroid hormones, T3, and/or T4. "Combination therapy" involves administration of both T3 and T4, and was technically the first treatment for hypothyroidism. It was lauded as a cure for the morbidity and mortality associated with myxedema, the most severe presentation of overt hypothyroidism. In the late nineteenth and the early Twentieth centuries, combination therapy per se could consist of thyroid gland transplant, or more commonly, consumption of desiccated animal thyroid, thyroid extract, or thyroglobulin. Combination therapy remained the mainstay of therapy for decades despite development of synthetic formulations of T4 and T3, because it was efficacious and cost effective. However, concerns emerged about the consistency and potency of desiccated thyroid hormone after cases were reported detailing either continued hypothyroidism or iatrogenic thyrotoxicosis. Development of the TSH radioimmunoassay and discovery of conversion of T4-to-T3 in humans led to a major transition in clinical practices away from combination therapy, to adoption of levothyroxine "monotherapy" as the standard of care. Levothyroxine monotherapy has a favorable safety profile and can effectively normalize the serum TSH, the most sensitive marker of hypothyroidism. Whether levothyroxine monotherapy restores thyroid hormone signaling within all tissues remains controversial. Evidence of persistent signs and symptoms of hypothyroidism during levothyroxine monotherapy at doses that normalize serum TSH is mounting. Hence, in the last decade there has been acknowledgment by all thyroid professional societies that there may be a role for the use of combination therapy; this represents a significant shift in the clinical practice guidelines. Further bolstering this trend are the recent findings that the Thr92AlaD2 polymorphism may reduce thyroid hormone signaling, resulting in localized and systemic hypothyroidism. This strengthens the hypothesis that treatment options could be personalized, taking into consideration genotypes and comorbidities. The development of long-acting formulations of liothyronine and continued advancements in development of thyroid regenerative therapy, may propel the field closer to adoption of a physiologic thyroid hormone replacement regimen with combination therapy.
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Affiliation(s)
- Elizabeth A. McAninch
- Division of Endocrinology and Metabolism, Rush University Medical Center, Chicago, IL, United States
| | - Antonio C. Bianco
- Section of Endocrinology and Metabolism, University of Chicago, Chicago, IL, United States
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Rurale G, Cicco ED, Dentice M, Salvatore D, Persani L, Marelli F, Luongo C. Thyroid Hormone Hyposensitivity: From Genotype to Phenotype and Back. Front Endocrinol (Lausanne) 2019; 10:912. [PMID: 32038483 PMCID: PMC6992580 DOI: 10.3389/fendo.2019.00912] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 12/16/2019] [Indexed: 01/24/2023] Open
Abstract
Thyroid hormone action defects (THADs) have been classically considered conditions of impaired sensitivity to thyroid hormone (TH). They were originally referring to alterations in TH receptor genes (THRA and THRB), but the discovery of genetic mutations and polymorphisms causing alterations in cell membrane transport (e.g., MCT8) and metabolism (e.g., SECISBP2, DIO2) led recently to a new and broader definition of TH hyposensitivity (THH), including not only THADs but all defects that could interfere with the activity of TH. Due to the different functions and tissue-specific expression of these genes, affected patients exhibit highly variable phenotypes. Some of them are characterized by a tissue hypothyroidism or well-recognizable alterations in the thyroid function tests (TFTs), whereas others display a combination of hypo- and hyperthyroid manifestations with normal or only subtle biochemical defects. The huge effort of basic research has greatly aided the comprehension of the molecular mechanisms underlying THADs, dissecting the morphological and functional alterations on target tissues, and defining the related-changes in the biochemical profile. In this review, we describe different pictures in which a specific alteration in the TFTs (TSH, T4, and T3 levels) is caused by defects in a specific gene. Altogether these findings can help clinicians to early recognize and diagnose THH and to perform a more precise genetic screening and therapeutic intervention. On the other hand, the identification of new genetic variants will allow the generation of cell-based and animal models to give novel insight into thyroid physiology and establish new therapeutic interventions.
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Affiliation(s)
- Giuditta Rurale
- Division of Endocrine and Metabolic Diseases, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Emery Di Cicco
- Department of Clinical Medicine & Surgery, University of Naples Federico II, Naples, Italy
| | - Monica Dentice
- Department of Clinical Medicine & Surgery, University of Naples Federico II, Naples, Italy
| | - Domenico Salvatore
- Department of Public Health, University of Naples Federico II, Naples, Italy
| | - Luca Persani
- Division of Endocrine and Metabolic Diseases, IRCCS Istituto Auxologico Italiano, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Federica Marelli
- Division of Endocrine and Metabolic Diseases, IRCCS Istituto Auxologico Italiano, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- *Correspondence: Federica Marelli
| | - Cristina Luongo
- Department of Public Health, University of Naples Federico II, Naples, Italy
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Abstract
Treatment of hypothyroidism involves the endogenous conversion of thyroxine (T4) to 3,5,3'-triiodothyronine (T3) and may not be optimal in some cases when based on T4 alone. In the current issue of the JCI, Jo et al. present results that explain the reduced enzymatic activity of a common genetic variant of the enzyme responsible for this conversion, type 2 deiodinase (DIO2). The authors further explore the functional consequences of this variant on brain T3 activity, endoplasmic reticulum stress in glial cells, and cognitive function. These findings have important implications for the clinical treatment of hypothyroidism and for susceptibility to other neurological and metabolic diseases.
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