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Liao XH, Avalos P, Shelest O, Ofan R, Shilo M, Bresee C, Likhite S, Vit JP, Heuer H, Kaspar B, Meyer K, Dumitrescu AM, Refetoff S, Svendsen CN, Vatine GD. AAV9-MCT8 Delivery at Juvenile Stage Ameliorates Neurological and Behavioral Deficits in a Mouse Model of MCT8-Deficiency. Thyroid 2022; 32:849-859. [PMID: 35350867 PMCID: PMC9469747 DOI: 10.1089/thy.2022.0034] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Background: Allan-Herndon-Dudley syndrome (AHDS) is a severe psychomotor disability disorder that also manifests characteristic abnormal thyroid hormone (TH) levels. AHDS is caused by inactivating mutations in monocarboxylate transporter 8 (MCT8), a specific TH plasma membrane transporter widely expressed in the central nervous system (CNS). MCT8 mutations cause impaired transport of TH across brain barriers, leading to insufficient neural TH supply. There is currently no successful therapy for the neurological symptoms. Earlier work has shown that intravenous (IV), but not intracerebroventricular adeno-associated virus serotype 9 (AAV9) -based gene therapy given to newborn Mct8 knockout (Mct8-/y) male mice increased triiodothyronine (T3) brain content and partially rescued TH-dependent gene expression, suggesting a promising approach to treat this neurological disorder. Methods: The potential of IV delivery of AAV9 carrying human MCT8 was tested in the well-established Mct8-/y/Organic anion-transporting polypeptide 1c1 (Oatp1c1)-/ - double knockout (dKO) mouse model of AHDS, which, unlike Mct8-/y mice, displays both neurological and TH phenotype. Further, as the condition is usually diagnosed during childhood, treatment was given intravenously to P30 mice and psychomotor tests were carried out blindly at P120-P140 after which tissues were collected and analyzed. Results: Systemic IV delivery of AAV9-MCT8 at a juvenile stage led to improved locomotor and cognitive functions at P120-P140, which was accompanied by a near normalization of T3 content and an increased response of positively regulated TH-dependent gene expression in different brain regions examined (thalamus, hippocampus, and parietal cortex). The effects on serum TH concentrations and peripheral tissues were less pronounced, showing only improvement in the serum T3/reverse T3 (rT3) ratio and in liver deiodinase 1 expression. Conclusion: IV administration of AAV9, carrying the human MCT8, to juvenile dKO mice manifesting AHDS has long-term beneficial effects, predominantly on the CNS. This preclinical study indicates that this gene therapy has the potential to ameliorate the devastating neurological symptoms in patients with AHDS.
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Affiliation(s)
- Xiao-Hui Liao
- Department of Medicine, The University of Chicago, Chicago, Illinois, USA
| | - Pablo Avalos
- The Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Oksana Shelest
- The Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Raz Ofan
- Department of Biotechnology Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
- The Regenerative Medicine and Stem Cell (RMSC) Research Center, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Michael Shilo
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Catherine Bresee
- Biostatistics Core, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Shibi Likhite
- The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Jean-Philippe Vit
- The Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Heike Heuer
- Department of Endocrinology, Diabetes and Metabolism, University of Duisburg-Essen, Essen, Germany
| | - Brian Kaspar
- The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Kathrin Meyer
- The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | | | - Samuel Refetoff
- Department of Medicine, The University of Chicago, Chicago, Illinois, USA
- Department of Pediatrics, The University of Chicago, Chicago, Illinois, USA
- Committee on Genetics, The University of Chicago, Chicago, Illinois, USA
- Address correspondence to: Samuel Refetoff, MD, Department of Medicine, The University of Chicago, MC3090, 5841 South Maryland Avenue, Chicago, IL 60637, USA
| | - Clive N. Svendsen
- The Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
- Address correspondence to: Clive N. Svendsen, PhD, The Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd, Los Angeles, CA 90048, USA
| | - Gad D. Vatine
- The Regenerative Medicine and Stem Cell (RMSC) Research Center, Ben-Gurion University of the Negev, Beer Sheva, Israel
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
- The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer Sheva, Israel
- Address correspondence to: Gad D. Vatine, PhD, Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
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2
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Wolff TM, Veil C, Dietrich JW, Müller MA. Mathematical modeling and simulation of thyroid homeostasis: Implications for the Allan-Herndon-Dudley syndrome. Front Endocrinol (Lausanne) 2022; 13:882788. [PMID: 36568087 PMCID: PMC9772020 DOI: 10.3389/fendo.2022.882788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 10/31/2022] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION A mathematical model of the pituitary-thyroid feedback loop is extended to deepen the understanding of the Allan-Herndon-Dudley syndrome (AHDS). The AHDS is characterized by unusual thyroid hormone concentrations and a mutation in the SLC16A2 gene encoding for the monocarboxylate transporter 8 (MCT8). This mutation leads to a loss of thyroid hormone transport activity. One hypothesis to explain the unusual hormone concentrations of AHDS patients is that due to the loss of thyroid hormone transport activity, thyroxine (T 4) is partially retained in thyroid cells. METHODS This hypothesis is investigated by extending a mathematical model of the pituitary-thyroid feedback loop to include a model of the net effects of membrane transporters such that the thyroid hormone transport activity can be considered. A nonlinear modeling approach based on the Michaelis-Menten kinetics and its linear approximation are employed to consider the membrane transporters. The unknown parameters are estimated through a constrained parameter optimization. RESULTS In dynamic simulations, damaged membrane transporters result in a retention of T 4 in thyroid cells and ultimately in the unusual hormone concentrations of AHDS patients. The Michaelis-Menten modeling approach and its linear approximation lead to similar results. DISCUSSION The results support the hypothesis that a partial retention of T 4 in thyroid cells represents one mechanism responsible for the unusual hormone concentrations of AHDS patients. Moreover, our results suggest that the retention of T 4 in thyroid cells could be the main reason for the unusual hormone concentrations of AHDS patients.
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Affiliation(s)
- Tobias M. Wolff
- Institute of Automatic Control, Leibniz University Hannover, Hannover, Germany
- *Correspondence: Tobias M. Wolff,
| | - Carina Veil
- Institute for System Dynamics, University of Stuttgart, Stuttgart, Germany
| | - Johannes W. Dietrich
- Diabetes, Endocrinology and Metabolism Section, Department of Internal Medicine I, St. Josef Hospital, Ruhr University Bochum, Bochum, Germany
- Diabetes Centre Bochum-Hattingen, St. Elisabeth-Hospital Blankenstein, Hattingen, Germany
- Ruhr Center for RareDiseases (CeSER), Ruhr University of Bochum and Witten/Herdecke University, Bochum, Germany
| | - Matthias A. Müller
- Institute of Automatic Control, Leibniz University Hannover, Hannover, Germany
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3
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Iwayama H, Kakita H, Iwasa M, Adachi S, Takano K, Kikuchi M, Fujisawa Y, Osaka H, Yamada Y, Okumura A, Hirani K, Weiss RE, Refetoff S. Measurement of Reverse Triiodothyronine Level and the Triiodothyronine to Reverse Triiodothyronine Ratio in Dried Blood Spot Samples at Birth May Facilitate Early Detection of Monocarboxylate Transporter 8 Deficiency. Thyroid 2021; 31:1316-1321. [PMID: 34049438 PMCID: PMC8558056 DOI: 10.1089/thy.2020.0696] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Background: Monocarboxylate transporter 8 (MCT8) deficiency is an X-chromosome-linked neurodevelopmental disorder resulting from impaired thyroid hormone transport across the cell membrane. The diagnosis of MCT8 deficiency is typically delayed owing to the late appearance of signs and symptoms as well as the inability of standard biomarkers of neonatal screening to provide early detection. In this study, we report, for the first time, the ability to detect MCT8 deficiency at birth using dried blood spot (DBS) samples. Methods: We retrospectively measured triiodothyronine (T3), thyroxine (T4), and reverse T3 (rT3) levels in DBS samples obtained at 4-5 days of life from 6 infants with genetically confirmed MCT8 deficiency and from 110 controls. The latter consisted of 58 healthy term neonates obtained at the same time, 16 were stored for more than 1 year before measurement to match samples from the MCT8-deficient infants. Ten DBS samples were collected at day 1 of life and 42 samples were from prematurely born neonates. Measurements were carried out in extract from eight millimeters diameter DBS using liquid chromatography-tandem mass spectrometry. Results: Contrary to characteristic iodothyronine abnormalities of MCT8 deficiency during later life, T3 and T4 values were not discriminatory from those of other study groups. In contrast, rT3 was significantly lower. The T3/rT3 ratio was higher in the DBS samples from the MCT8-deficient infants compared with all other groups with no overlap (p < 0.0001). Conclusions: rT3 and T3/rT3 ratio in DBS samples obtained from neonates can serve as biomarkers to detect MCT8 deficiency at birth.
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Affiliation(s)
- Hideyuki Iwayama
- Department of Pediatrics, School of Medicine, Aichi Medical University, Nagakute, Japan
| | - Hiroki Kakita
- Department of Perinatal and Neonatal Medicine, School of Medicine, Aichi Medical University, Nagakute, Japan
| | - Masumi Iwasa
- Department of Pediatrics, School of Medicine, Aichi Medical University, Nagakute, Japan
| | - Shinsuke Adachi
- Department of Pediatrics, Fukuchiyama City Hospital, Kyoto, Japan
| | - Kyoko Takano
- Center for Medical Genetics, Shinshu University Hospital, Nagano, Japan
| | - Masahiro Kikuchi
- Department of Pediatrics, Hitachi General Hospital, Hitachi, Japan
| | - Yasuko Fujisawa
- Department of Pediatrics, School of Medicine, Hamamatsu University, Hamamatsu, Japan
| | - Hitoshi Osaka
- Department of Pediatrics, Jichi Medical School, Shimotsuke, Japan
| | - Yasumasa Yamada
- Department of Perinatal and Neonatal Medicine, School of Medicine, Aichi Medical University, Nagakute, Japan
| | - Akihisa Okumura
- Department of Pediatrics, School of Medicine, Aichi Medical University, Nagakute, Japan
| | - Khemraj Hirani
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Roy E. Weiss
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Samuel Refetoff
- Departments of Medicine, Pediatrics and Committee on Genetics, The University of Chicago, Chicago, Illinois, USA
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4
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Jankauskas SS, Morelli MB, Gambardella J, Lombardi A, Santulli G. Thyroid hormones regulate both cardiovascular and renal mechanisms underlying hypertension. J Clin Hypertens (Greenwich) 2020; 23:373-381. [PMID: 33377271 PMCID: PMC8030083 DOI: 10.1111/jch.14152] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/27/2020] [Accepted: 12/13/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Stanislovas S Jankauskas
- Department of Medicine, Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Fleischer Institute for Diabetes and Metabolism (FIDAM), Albert Einstein College of Medicine, New York, NY, USA
| | - Marco B Morelli
- Department of Medicine, Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Fleischer Institute for Diabetes and Metabolism (FIDAM), Albert Einstein College of Medicine, New York, NY, USA.,Department of Molecular Pharmacology, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY, USA
| | - Jessica Gambardella
- Department of Medicine, Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Fleischer Institute for Diabetes and Metabolism (FIDAM), Albert Einstein College of Medicine, New York, NY, USA.,Department of Molecular Pharmacology, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY, USA.,Department of Advanced Biomedical Science, "Federico II" University, and International Translational Research and Medical Education Consortium (ITME), Naples, Italy
| | - Angela Lombardi
- Department of Medicine, Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Fleischer Institute for Diabetes and Metabolism (FIDAM), Albert Einstein College of Medicine, New York, NY, USA.,Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, NY, USA
| | - Gaetano Santulli
- Department of Medicine, Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Fleischer Institute for Diabetes and Metabolism (FIDAM), Albert Einstein College of Medicine, New York, NY, USA.,Department of Molecular Pharmacology, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY, USA.,Department of Advanced Biomedical Science, "Federico II" University, and International Translational Research and Medical Education Consortium (ITME), Naples, Italy
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5
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Groeneweg S, van Geest FS, Peeters RP, Heuer H, Visser WE. Thyroid Hormone Transporters. Endocr Rev 2020; 41:5637505. [PMID: 31754699 DOI: 10.1210/endrev/bnz008] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/07/2019] [Indexed: 02/08/2023]
Abstract
Thyroid hormone transporters at the plasma membrane govern intracellular bioavailability of thyroid hormone. Monocarboxylate transporter (MCT) 8 and MCT10, organic anion transporting polypeptide (OATP) 1C1, and SLC17A4 are currently known as transporters displaying the highest specificity toward thyroid hormones. Structure-function studies using homology modeling and mutational screens have led to better understanding of the molecular basis of thyroid hormone transport. Mutations in MCT8 and in OATP1C1 have been associated with clinical disorders. Different animal models have provided insight into the functional role of thyroid hormone transporters, in particular MCT8. Different treatment strategies for MCT8 deficiency have been explored, of which thyroid hormone analogue therapy is currently applied in patients. Future studies may reveal the identity of as-yet-undiscovered thyroid hormone transporters. Complementary studies employing animal and human models will provide further insight into the role of transporters in health and disease. (Endocrine Reviews 41: 1 - 55, 2020).
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Affiliation(s)
- Stefan Groeneweg
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Ferdy S van Geest
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Robin P Peeters
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Heike Heuer
- Department of Endocrinology, Diabetes and Metabolism, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - W Edward Visser
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
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6
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Salveridou E, Mayerl S, Sundaram SM, Markova B, Heuer H. Tissue-Specific Function of Thyroid Hormone Transporters: New Insights from Mouse Models. Exp Clin Endocrinol Diabetes 2019; 128:423-427. [PMID: 31724131 DOI: 10.1055/a-1032-8328] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Thyroid hormone (TH) transporters are required for cellular transmembrane passage of TH and are thus mandatory for proper TH metabolism and action. Consequently, inactivating mutations in TH transporters such as MCT8 or OATP1C1 can cause tissue- specific changes in TH homeostasis. As the most prominent example, patients with MCT8 mutations exhibit elevated serum T3 levels, whereas their CNS appear to be in a TH deficient state. Here, we will briefly summarize recent studies of mice lacking Mct8 alone or in combination with the TH transporters Mct10 or Oatp1c1 that shed light on many aspects and pathogenic events underlying global MCT8 deficiency and also underscore the contribution of Mct10 and Oatp1c1 in tissue-specific TH transport processes. Moreover, development of conditional knock-out mice that allow a cell-specific inactivation of TH transporters in distinct tissues, disclosed cell-specific changes in TH signaling, thereby highlighting the pathophysiological significance of local control of TH action.
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Affiliation(s)
- Eva Salveridou
- Department of Endocrinology, Diabetes and Metabolism, University of Duisburg-Essen, Essen, Germany.,Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany
| | - Steffen Mayerl
- Department of Endocrinology, Diabetes and Metabolism, University of Duisburg-Essen, Essen, Germany.,MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - Sivaraj Mohana Sundaram
- Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany.,Institute of Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
| | - Boyka Markova
- Department of Endocrinology, Diabetes and Metabolism, University of Duisburg-Essen, Essen, Germany.,Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany
| | - Heike Heuer
- Department of Endocrinology, Diabetes and Metabolism, University of Duisburg-Essen, Essen, Germany.,Leibniz Research Institute for Environmental Medicine (IUF), Düsseldorf, Germany
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7
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Bárez-López S, Grijota-Martínez C, Ausó E, Fernández-de Frutos M, Montero-Pedrazuela A, Guadaño-Ferraz A. Adult Mice Lacking Mct8 and Dio2 Proteins Present Alterations in Peripheral Thyroid Hormone Levels and Severe Brain and Motor Skill Impairments. Thyroid 2019; 29:1669-1682. [PMID: 31359845 DOI: 10.1089/thy.2019.0068] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background: Mutations in the thyroid hormone (TH) transporter monocarboxylate transporter 8 (MCT8) lead to peripheral hyperthyroidism and profound psychomotor alterations in humans. Mice lacking Mct8 present peripheral hyperthyroidism but no gross neurological abnormalities due to brain compensatory mechanisms involving the enzyme deiodinase type 2 (Dio2). Methods: Here we have analyzed the endocrine and neurologic phenotype of mice lacking both Mct8 and Dio2 at three and six months of age. Thyroxine (T4) and 3,5,3' triiodothyronine (T3) levels/content were measured by specific radioimmunoassays; motor skill performance was evaluated by the footprint, rotarod, four limb hanging wire, and balance beam tests; and brain histological analysis was performed by immunostaining for neurofilament and parvalbumin. Results: We have found that this mouse model presents peripheral hyperthyroidism and brain hypothyroidism. Interestingly, the severity of the brain hypothyroidism seems permanent and varies across regions, with the striatum being a particularly affected area. We have also found brain alterations at the histological level compatible with TH deficiency and impaired motor skills. Conclusions: These findings indicate the potential of Mct8/Dio2-deficient mice to represent a model for human MCT8 deficiency, to understand the mechanisms underlying its pathophysiology, and ultimately design therapeutic interventions for human patients.
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Affiliation(s)
- Soledad Bárez-López
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Unit 708, Center for Biomedical Research On Rare Diseases (Ciberer), Instituto de Salud Carlos III, Madrid, Spain
| | - Carmen Grijota-Martínez
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Unit 708, Center for Biomedical Research On Rare Diseases (Ciberer), Instituto de Salud Carlos III, Madrid, Spain
| | - Eva Ausó
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Departamento de Óptica, Farmacología y Anatomía, Universidad de Alicante, Alicante, Spain
| | - Mario Fernández-de Frutos
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Ana Montero-Pedrazuela
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Ana Guadaño-Ferraz
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Unit 708, Center for Biomedical Research On Rare Diseases (Ciberer), Instituto de Salud Carlos III, Madrid, Spain
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8
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Islam MS, Namba N, Ohata Y, Fujiwara M, Nakano C, Takeyari S, Miyata K, Nakano Y, Yamamoto K, Nakayama H, Kitaoka T, Kubota T, Ozono K. Functional analysis of monocarboxylate transporter 8 mutations in Japanese Allan-Herndon-Dudley syndrome patients. Endocr J 2019; 66:19-29. [PMID: 30369548 DOI: 10.1507/endocrj.ej18-0251] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Monocarboxylate transporter 8 (MCT8) facilitates T3 uptake into cells. Mutations in MCT8 lead to Allan-Herndon-Dudley syndrome (AHDS), which is characterized by severe psychomotor retardation and abnormal thyroid hormone profile. Nine uncharacterized MCT8 mutations in Japanese patients with severe neurocognitive impairment and elevated serum T3 levels were studied regarding the transport of T3. Human MCT8 (hMCT8) function was studied in wild-type (WT) or mutant hMCT8-transfected human placental choriocarcinoma cells (JEG3) by visualizing the locations of the proteins in the cells, detecting specific proteins, and measuring T3 uptake. We identified 6 missense (p.Arg445Ser, p.Asp498Asn, p.Gly276Arg, p.Gly196Glu, p.Gly401Arg, and p.Gly312Arg), 2 frameshift (p.Arg355Profs*64 and p.Tyr550Serfs*17), and 1 deletion (p.Pro561del) mutation(s) in the hMCT8 gene. All patients exhibited clinical characteristics of AHDS with high free T3, low-normal free T4, and normal-elevated TSH levels. All tested mutants were expressed at the protein level, except p.Arg355Profs*64 and p.Tyr550Serfs*17, which were truncated, and were inactive in T3 uptake, excluding p.Arg445Ser and p.Pro561del mutants, compared with WT-hMCT8. Immunocytochemistry revealed plasma membrane localization of p.Arg445Ser and p.Pro561del mutants similar with WT-hMCT8. The other mutants failed to localize in significant amount(s) in the plasma membrane and instead localized in the cytoplasm. These data indicate that p.Arg445Ser and p.Pro561del mutants preserve residual function, whereas p.Asp498Asn, p.Gly276Arg, p.Gly196Glu, p.Gly401Arg, p.Gly312Arg, p.Arg355Profs*64, and p.Tyr550Serfs*17 mutants lack function. These findings suggest that the mutations in MCT8 cause loss of function by reducing protein expression, impairing trafficking of protein to plasma membrane, and disrupting substrate channel.
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Affiliation(s)
- Mohammad Saiful Islam
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Noriyuki Namba
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization, Osaka, Japan
| | - Yasuhisa Ohata
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
- The First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Suita, Japan
| | - Makoto Fujiwara
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine, USA
| | - Chiho Nakano
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
- The First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, Suita, Japan
| | - Shinji Takeyari
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Kei Miyata
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Yukako Nakano
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Kenichi Yamamoto
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
- Department of Statistical Genetics, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Hirofumi Nakayama
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
- The Japan Environment and Children's Study, Osaka Unit Center, Suita, Japan
| | - Taichi Kitaoka
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Takuo Kubota
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
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9
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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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11
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Weber J, McInnes J, Kizilirmak C, Rehders M, Qatato M, Wirth EK, Schweizer U, Verrey F, Heuer H, Brix K. Interdependence of thyroglobulin processing and thyroid hormone export in the mouse thyroid gland. Eur J Cell Biol 2017; 96:440-456. [PMID: 28274595 DOI: 10.1016/j.ejcb.2017.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/08/2017] [Accepted: 02/09/2017] [Indexed: 02/08/2023] Open
Abstract
Thyroid hormone (TH) target cells need to adopt mechanisms to maintain sufficient levels of TH to ensure regular functions. This includes thyroid epithelial cells, which generate TH in addition to being TH-responsive. However, the cellular and molecular pathways underlying thyroid auto-regulation are insufficiently understood. In order to investigate whether thyroglobulin processing and TH export are sensed by thyrocytes, we inactivated thyroglobulin-processing cathepsins and TH-exporting monocarboxylate transporters (Mct) in the mouse. The states of thyroglobulin storage and its protease-mediated processing and degradation were related to the levels of TH transporter molecules by immunoblotting and immunofluorescence microscopy. Thyroid epithelial cells of cathepsin-deficient mice showed increased Mct8 protein levels at the basolateral plasma membrane domains when compared to wild type controls. While the protein amounts of the thyroglobulin-degrading cathepsin D remained largely unaffected by Mct8 or Mct10 single-deficiencies, a significant increase in the amounts of the thyroglobulin-processing cathepsins B and L was detectable in particular in Mct8/Mct10 double deficiency. In addition, it was observed that larger endo-lysosomes containing cathepsins B, D, and L were typical for Mct8- and/or Mct10-deficient mouse thyroid epithelial cells. These data support the notion of a crosstalk between TH transporters and thyroglobulin-processing proteases in thyroid epithelial cells. We conclude that a defect in exporting thyroxine from thyroid follicles feeds back positively on its cathepsin-mediated proteolytic liberation from the precursor thyroglobulin, thereby adding to the development of auto-thyrotoxic states in Mct8 and/or Mct10 deficiencies. The data suggest TH sensing molecules within thyrocytes that contribute to thyroid auto-regulation.
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Affiliation(s)
- Jonas Weber
- Jacobs University Bremen, Department of Life Sciences and Chemistry, Campus Ring 1, D-28759 Bremen, Germany
| | - Joseph McInnes
- Jacobs University Bremen, Department of Life Sciences and Chemistry, Campus Ring 1, D-28759 Bremen, Germany
| | - Cise Kizilirmak
- Jacobs University Bremen, Department of Life Sciences and Chemistry, Campus Ring 1, D-28759 Bremen, Germany
| | - Maren Rehders
- Jacobs University Bremen, Department of Life Sciences and Chemistry, Campus Ring 1, D-28759 Bremen, Germany
| | - Maria Qatato
- Jacobs University Bremen, Department of Life Sciences and Chemistry, Campus Ring 1, D-28759 Bremen, Germany
| | - Eva K Wirth
- Charité-Universitätsmedizin Berlin, Institut für Experimentelle Endokrinologie, Augustenburger Platz 1, D-13353 Berlin, Germany
| | - Ulrich Schweizer
- Universität Bonn, Institut für Biochemie und Molekularbiologie, Nußallee 11, D-53115 Bonn, Germany
| | - Francois Verrey
- Universität Zürich, Physiologisches Institut, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Heike Heuer
- IUF - Leibniz Institut für umweltmedizinische Forschung, Auf'm Hennekamp 50, D-40225 Düsseldorf, Germany
| | - Klaudia Brix
- Jacobs University Bremen, Department of Life Sciences and Chemistry, Campus Ring 1, D-28759 Bremen, Germany.
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Abstract
Transport of thyroid hormone (TH) across the plasma membrane is essential for intracellular TH metabolism and action, and this is mediated by specific transporter proteins. During the last two decades several transporters capable of transporting TH have been identified, including monocarboxylate transporter 8 (MCT8), MCT10 and organic anion transporting polypeptide 1C1 (OATP1C1). In particular MCT8 and OATP1C1 are important for the regulation of local TH activity in the brain and thus for brain development. MCT8 is a protein containing 12 transmembrane domains, and is encoded by the SLC16A2 gene located on the X chromosome. It facilitates both TH uptake and efflux across the cell membrane. Male subjects with hemizygous mutations in MCT8 are afflicted with severe intellectual and motor disability, also known as the Allan-Herndon-Dudley syndrome (AHDS), which goes together with low serum T4 and high T3 levels. This review concerns molecular and clinical aspects of MCT8 function.
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Affiliation(s)
- Stefan Groeneweg
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
| | - W Edward Visser
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
| | - Theo J Visser
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
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13
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Charzewska A, Wierzba J, Iżycka-Świeszewska E, Bekiesińska-Figatowska M, Jurek M, Gintowt A, Kłosowska A, Bal J, Hoffman-Zacharska D. Hypomyelinating leukodystrophies - a molecular insight into the white matter pathology. Clin Genet 2016; 90:293-304. [DOI: 10.1111/cge.12811] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/24/2016] [Accepted: 05/25/2016] [Indexed: 12/23/2022]
Affiliation(s)
- A. Charzewska
- Institute of Mother and Child, Department of Medical Genetics; Warsaw Poland
| | - J. Wierzba
- Medical University of Gdańsk; Department of Paediatrics, Haemathology & Oncology, Department of General Nursery; Gdańsk Poland
| | - E. Iżycka-Świeszewska
- Medical University of Gdańsk; Department of Pathology & Neuropathology; Copernicus Hospital, Department of Patomorphology; Gdańsk Poland
| | | | - M. Jurek
- Institute of Mother and Child, Department of Medical Genetics; Warsaw Poland
| | - A. Gintowt
- Medical University of Gdańsk; Department of Biology and Genetics; Gdańsk Poland
| | - A. Kłosowska
- Medical University of Gdańsk; Department of Paediatrics, Haemathology & Oncology, Department of General Nursery; Gdańsk Poland
| | - J. Bal
- Institute of Mother and Child, Department of Medical Genetics; Warsaw Poland
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14
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Vujovic M, Dudazy-Gralla S, Hård J, Solsjö P, Warner A, Vennström B, Mittag J. Thyroid hormone drives the expression of mouse carbonic anhydrase Car4 in kidney, lung and brain. Mol Cell Endocrinol 2015; 416:19-26. [PMID: 26319697 DOI: 10.1016/j.mce.2015.08.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 08/11/2015] [Accepted: 08/11/2015] [Indexed: 10/23/2022]
Abstract
Thyroid hormone is a well-known regulator of brain, lung and kidney development and function. However, the molecular mechanisms by which the hormone exerts its function have remained largely enigmatic, and only a limited set of target genes have been identified in these tissues. Using a mouse model with a mutation in thyroid hormone receptor α1 (TRα1), we here demonstrate that the expression of carbonic anhydrase 4 in lung and brain of the adult animal depends on intact TRα1 signaling. In the kidney, carbonic anhydrase 4 mRNA and protein are not affected by the mutant TRα1, but are acutely repressed by thyroid hormone. However, neither lung function--as measured by respiration rate and oxygen saturation--nor urine pH levels were affected by altered carbonic anhydrase 4 levels, suggesting that other carbonic anhydrases are likely to compensate. Taken together, our findings identify a previously unknown marker of TRα1 action in brain and lung, and provide a novel negatively regulated target gene to assess renal thyroid hormone status.
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Affiliation(s)
- Milica Vujovic
- Karolinska Institutet, Department of Cell and Molecular Biology, 17177 Stockholm, Sweden
| | - Susi Dudazy-Gralla
- Karolinska Institutet, Department of Cell and Molecular Biology, 17177 Stockholm, Sweden
| | - Joanna Hård
- Karolinska Institutet, Department of Cell and Molecular Biology, 17177 Stockholm, Sweden
| | - Peter Solsjö
- Karolinska Institutet, Department of Cell and Molecular Biology, 17177 Stockholm, Sweden
| | - Amy Warner
- Karolinska Institutet, Department of Cell and Molecular Biology, 17177 Stockholm, Sweden
| | - Björn Vennström
- Karolinska Institutet, Department of Cell and Molecular Biology, 17177 Stockholm, Sweden
| | - Jens Mittag
- Karolinska Institutet, Department of Cell and Molecular Biology, 17177 Stockholm, Sweden; Universität zu Lübeck, Medizinische Klinik 1/Center of Brain, Behavior and Metabolism, Ratzeburger Allee 160, 23562 Lübeck, Germany.
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15
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Ferrara AM, Liao XH, Ye H, Weiss RE, Dumitrescu AM, Refetoff S. The Thyroid Hormone Analog DITPA Ameliorates Metabolic Parameters of Male Mice With Mct8 Deficiency. Endocrinology 2015; 156:3889-94. [PMID: 26322373 PMCID: PMC4606752 DOI: 10.1210/en.2015-1234] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mutations in the gene encoding the thyroid hormone (TH) transporter, monocarboxylate transporter 8 (MCT8), cause mental retardation in humans associated with a specific thyroid hormone phenotype manifesting high serum T3 and low T4 and rT3 levels. Moreover, these patients have failure to thrive, and physiological changes compatible with thyrotoxicosis. Recent studies in Mct8-deficient (Mct8KO) mice revealed that the high serum T3 causes increased energy expenditure. The TH analog, diiodothyropropionic acid (DITPA), enters cells independently of Mct8 transport and shows thyromimetic action but with a lower metabolic activity than TH. In this study DITPA was given daily ip to adult Mct8KO mice to determine its effect on thyroid tests in serum and metabolism (total energy expenditure, respiratory exchange rate, and food and water intake). In addition, we measured the expression of TH-responsive genes in the brain, liver, and muscles to assess the thyromimetic effects of DITPA. Administration of 0.3 mg DITPA per 100 g body weight to Mct8KO mice brought serum T3 levels and the metabolic parameters studied to levels observed in untreated Wt animals. Analysis of TH target genes revealed amelioration of the thyrotoxic state in liver, somewhat in the soleus, but there was no amelioration of the brain hypothyroidism. In conclusion, at the dose used, DITPA mainly ameliorated the hypermetabolism of Mct8KO mice. This thyroid hormone analog is suitable for the treatment of the hypermetabolism in patients with MCT8 deficiency, as suggested in limited preliminary human trials.
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Affiliation(s)
- Alfonso Massimiliano Ferrara
- Departments of Medicine (A.M.F., X.-H.L., H.Y., R.E.W., A.M.D., S.R.) and Pediatrics (R.E.W., S.R.) and the Committee on Genetics (S.R.), The University of Chicago, Chicago, Illinois 60637
| | - Xiao-Hui Liao
- Departments of Medicine (A.M.F., X.-H.L., H.Y., R.E.W., A.M.D., S.R.) and Pediatrics (R.E.W., S.R.) and the Committee on Genetics (S.R.), The University of Chicago, Chicago, Illinois 60637
| | - Honggang Ye
- Departments of Medicine (A.M.F., X.-H.L., H.Y., R.E.W., A.M.D., S.R.) and Pediatrics (R.E.W., S.R.) and the Committee on Genetics (S.R.), The University of Chicago, Chicago, Illinois 60637
| | - Roy E Weiss
- Departments of Medicine (A.M.F., X.-H.L., H.Y., R.E.W., A.M.D., S.R.) and Pediatrics (R.E.W., S.R.) and the Committee on Genetics (S.R.), The University of Chicago, Chicago, Illinois 60637
| | - Alexandra M Dumitrescu
- Departments of Medicine (A.M.F., X.-H.L., H.Y., R.E.W., A.M.D., S.R.) and Pediatrics (R.E.W., S.R.) and the Committee on Genetics (S.R.), The University of Chicago, Chicago, Illinois 60637
| | - Samuel Refetoff
- Departments of Medicine (A.M.F., X.-H.L., H.Y., R.E.W., A.M.D., S.R.) and Pediatrics (R.E.W., S.R.) and the Committee on Genetics (S.R.), The University of Chicago, Chicago, Illinois 60637
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Wirth EK, Rijntjes E, Meyer F, Köhrle J, Schweizer U. High T3, Low T4 Serum Levels in Mct8 Deficiency Are Not Caused by Increased Hepatic Conversion through Type I Deiodinase. Eur Thyroid J 2015; 4:87-91. [PMID: 26601078 PMCID: PMC4640264 DOI: 10.1159/000381021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 02/16/2015] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The Allan-Herndon-Dudley syndrome is a severe psychomotor retardation accompanied by specific changes in circulating thyroid hormone levels (high T3, low T4). These are caused by mutations in the thyroid hormone transmembrane transport protein monocarboxylate transporter 8 (MCT8). OBJECTIVE To test the hypothesis that circulating low T4 and high T3 levels are caused by enhanced conversion of T4 via increased activity of hepatic type I deiodinase (Dio1). METHODS We crossed mice deficient in Mct8 with mice lacking Dio1 activity in hepatocytes. Translation of the selenoenzyme Dio1 was abrogated by hepatocyte-specific inactivation of selenoprotein biosynthesis. RESULTS Inactivation of Dio1 activity in the livers of global Mct8-deficient mice does not restore normal circulating thyroid hormone levels. CONCLUSIONS Our data suggest that although hepatic Dio1 activity is increased in Mct8-deficient mice, it does not cause the observed abnormal circulating thyroid hormone levels. Since global inactivation of Dio1 in Mct8-deficient mice does normalize circulating thyroid hormone levels, the underlying mechanism and relevant tissues involved remain to be elucidated.
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Affiliation(s)
- Eva K. Wirth
- *Dr. Eva K. Wirth, Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, DE-13353 Berlin (Germany), E-Mail
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17
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Abstract
The cellular influx and efflux of thyroid hormones are facilitated by transmembrane protein transporters. Of these transporters, monocarboxylate transporter 8 (MCT8) is the only one specific for the transport of thyroid hormones and some of their derivatives. Mutations in SLC16A2, the gene that encodes MCT8, lead to an X-linked syndrome with severe neurological impairment and altered concentrations of thyroid hormones. Histopathological analysis of brain tissue from patients who have impaired MCT8 function indicates that brain lesions start prenatally, and are most probably the result of cerebral hypothyroidism. A Slc16a2 knockout mouse model has revealed that Mct8 is an important mediator of thyroid hormone transport, especially T3, through the blood-brain barrier. However, unlike humans with an MCT8 deficiency, these mice do not have neurological impairment. One explanation for this discrepancy could be differences in expression of the T4 transporter OATP1C1 in the blood-brain barrier; OATP1C1 is more abundant in rodents than in primates and permits the passage of T4 in the absence of T3 transport, thus preventing full cerebral hypothyroidism. In this Review, we discuss the relevance of thyroid hormone transporters in health and disease, with a particular focus on the pathophysiology of MCT8 mutations.
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Affiliation(s)
- Juan Bernal
- Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), Arturo Duperier 4, 28029 Madrid, Spain
| | - Ana Guadaño-Ferraz
- Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), Arturo Duperier 4, 28029 Madrid, Spain
| | - Beatriz Morte
- Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Arturo Duperier 4, 28029 Madrid, Spain
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18
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Anık A, Kersseboom S, Demir K, Catlı G, Yiş U, Böber E, van Mullem A, van Herebeek REA, Hız S, Abacı A, Visser TJ. Psychomotor retardation caused by a defective thyroid hormone transporter: report of two families with different MCT8 mutations. Horm Res Paediatr 2015; 82:261-71. [PMID: 25247785 DOI: 10.1159/000365191] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 06/10/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Monocarboxylate transporter 8 (MCT8) is essential for thyroid hormone (TH) transport in the brain. Mutations in MCT8 are associated with the Allan-Herndon-Dudley syndrome (AHDS), characterized by severe psychomotor retardation and altered serum thyroid parameters. Here we report two novel mutations in MCT8 and discuss the clinical findings. CASE REPORT AND RESULTS We describe 4 males with AHDS from two unrelated families varying in age from 1.5 to 11 years. All 4 patients presented with typical clinical signs of AHDS, including severe psychomotor retardation, axial hypotonia, lack of speech, diminished muscle mass, increased muscle tone, hyperreflexia, myopathic facies, high T3, low T4 and rT3, and normal/mildly elevated TSH levels. Comparison of patients at different ages suggests the progressive nature of AHDS. Genetic analyses identified a novel missense MCT8 mutation (p.G495A) in family 1 and a 2.8-kb deletion comprising exons 3 and 4 in family 2. Functional analysis of p.G495A revealed impaired TH transport varying from 20 to 85% depending on the cell context. CONCLUSION Here we report 4 AHDS patients in unrelated Turkish families harboring novel MCT8 mutations. Despite the widely different mutations, the clinical phenotypes are very similar and findings support the progressive nature of AHDS.
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Affiliation(s)
- Ahmet Anık
- Department of Pediatric Endocrinology, Dokuz Eylul University, Izmir, Turkey
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19
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Li H, Moll J, Winkler A, Frappart L, Brunet S, Hamann J, Kroll T, Verlhac MH, Heuer H, Herrlich P, Ploubidou A. RHAMM deficiency disrupts folliculogenesis resulting in female hypofertility. Biol Open 2015; 4:562-71. [PMID: 25750434 PMCID: PMC4400598 DOI: 10.1242/bio.201410892] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The postnatal mammalian ovary contains the primary follicles, each comprising an immature oocyte surrounded by a layer of somatic granulosa cells. Oocytes reach meiotic and developmental competence via folliculogenesis. During this process, the granulosa cells proliferate massively around the oocyte, form an extensive extracellular matrix (ECM) and differentiate into cumulus cells. As the ECM component hyaluronic acid (HA) is thought to form the backbone of the oocyte-granulosa cell complex, we deleted the relevant domain of the Receptor for HA Mediated Motility (RHAMM) gene in the mouse. This resulted in folliculogenesis defects and female hypofertility, although HA-induced signalling was not affected. We report that wild-type RHAMM localises at the mitotic spindle of granulosa cells, surrounding the oocyte. Deletion of the RHAMM C-terminus in vivo abolishes its spindle association, resulting in impaired spindle orientation in the dividing granulosa cells, folliculogenesis defects and subsequent female hypofertility. These data reveal the first identified physiological function for RHAMM, during oogenesis, and the importance of this spindle-associated function for female fertility.
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Affiliation(s)
- Huaibiao Li
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Jürgen Moll
- Forschungszentrum Karlsruhe, Institut für Toxicologie und Genetik, Postfach 3640, D-76021 Karlsruhe, Germany Present address: Boehringer-Ingelheim RCV and Co KG, Dr. Boehringer-Gasse 5-11, A-1121 Vienna, Austria
| | - Anne Winkler
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany Present address: Georg-August-University Göttingen, Dept. of Neuropathology, Robert-Koch-Strasse 40, D-37075 Göttingen, Germany
| | - Lucien Frappart
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany INSERM, Oncogenèse et Progression Tumorale, Université Claude Bernard Lyon I, 28 rue Laënnec, 69373 Lyon, France
| | - Stéphane Brunet
- Collège de France, 11 place Marcelin Berthelot, 75231 Paris, France
| | - Jana Hamann
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Torsten Kroll
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | | | - Heike Heuer
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany Leibniz Research Institute for Environmental Medicine (IUF), 40021 Düsseldorf, Germany
| | - Peter Herrlich
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Aspasia Ploubidou
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
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20
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Moss DM, Neary M, Owen A. The role of drug transporters in the kidney: lessons from tenofovir. Front Pharmacol 2014; 5:248. [PMID: 25426075 PMCID: PMC4227492 DOI: 10.3389/fphar.2014.00248] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 10/24/2014] [Indexed: 12/15/2022] Open
Abstract
Tenofovir disoproxil fumarate, the prodrug of nucleotide reverse transcriptase inhibitor tenofovir, shows high efficacy and relatively low toxicity in HIV patients. However, long-term kidney toxicity is now acknowledged as a modest but significant risk for tenofovir-containing regimens, and continuous use of tenofovir in HIV therapy is currently under question by practitioners and researchers. Co-morbidities (hepatitis C, diabetes), low body weight, older age, concomitant administration of potentially nephrotoxic drugs, low CD4 count, and duration of therapy are all risk factors associated with tenofovir-associated tubular dysfunction. Tenofovir is predominantly eliminated via the proximal tubules of the kidney, therefore drug transporters expressed in renal proximal tubule cells are believed to influence tenofovir plasma concentration and toxicity in the kidney. We review here the current evidence that the actions, pharmacogenetics, and drug interactions of drug transporters are relevant factors for tenofovir-associated tubular dysfunction. The use of creatinine and novel biomarkers for kidney damage, and the role that drug transporters play in biomarker disposition, are discussed. The lessons learnt from investigating the role of transporters in tenofovir kidney elimination and toxicity can be utilized for future drug development and clinical management programs.
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Affiliation(s)
- Darren M Moss
- Department of Molecular and Clinical Pharmacology, University of Liverpool Liverpool, UK
| | - Megan Neary
- Department of Molecular and Clinical Pharmacology, University of Liverpool Liverpool, UK
| | - Andrew Owen
- Department of Molecular and Clinical Pharmacology, University of Liverpool Liverpool, UK
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21
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Schweizer U, Johannes J, Bayer D, Braun D. Structure and function of thyroid hormone plasma membrane transporters. Eur Thyroid J 2014; 3:143-53. [PMID: 25538896 PMCID: PMC4224232 DOI: 10.1159/000367858] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 08/26/2014] [Indexed: 01/25/2023] Open
Abstract
Thyroid hormones (TH) cross the plasma membrane with the help of transporter proteins. As charged amino acid derivatives, TH cannot simply diffuse across a lipid bilayer membrane, despite their notorious hydrophobicity. The identification of monocarboxylate transporter 8 (MCT8, SLC16A2) as a specific and very active TH transporter paved the way to the finding that mutations in the MCT8 gene cause a syndrome of psychomotor retardation in humans. The purpose of this review is to introduce the current model of transmembrane transport and highlight the diversity of TH transmembrane transporters. The interactions of TH with plasma transfer proteins, T3 receptors, and deiodinase are summarized. It is shown that proteins may bind TH owing to their hydrophobic character in hydrophobic cavities and/or by specific polar interaction with the phenolic hydroxyl, the aminopropionic acid moiety, and by weak polar interactions with the iodine atoms. These findings are compared with our understanding of how TH transporters interact with substrate. The presumed effects of mutations in MCT8 on protein folding and transport function are explained in light of the available homology model.
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Affiliation(s)
- Ulrich Schweizer
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
- *Prof. Dr. Ulrich Schweizer, Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 11, DE-53115 Bonn (Germany), E-Mail
| | - Jörg Johannes
- Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Dorothea Bayer
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Doreen Braun
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
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22
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Mayerl S, Müller J, Bauer R, Richert S, Kassmann CM, Darras VM, Buder K, Boelen A, Visser TJ, Heuer H. Transporters MCT8 and OATP1C1 maintain murine brain thyroid hormone homeostasis. J Clin Invest 2014; 124:1987-99. [PMID: 24691440 DOI: 10.1172/jci70324] [Citation(s) in RCA: 188] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 02/06/2014] [Indexed: 11/17/2022] Open
Abstract
Allan-Herndon-Dudley syndrome (AHDS), a severe form of psychomotor retardation with abnormal thyroid hormone (TH) parameters, is linked to mutations in the TH-specific monocarboxylate transporter MCT8. In mice, deletion of Mct8 (Mct8 KO) faithfully replicates AHDS-associated endocrine abnormalities; however, unlike patients, these animals do not exhibit neurological impairments. While transport of the active form of TH (T3) across the blood-brain barrier is strongly diminished in Mct8 KO animals, prohormone (T4) can still enter the brain, possibly due to the presence of T4-selective organic anion transporting polypeptide (OATP1C1). Here, we characterized mice deficient for both TH transporters, MCT8 and OATP1C1 (Mct8/Oatp1c1 DKO). Mct8/Oatp1c1 DKO mice exhibited alterations in peripheral TH homeostasis that were similar to those in Mct8 KO mice; however, uptake of both T3 and T4 into the brains of Mct8/Oatp1c1 DKO mice was strongly reduced. Evidence of TH deprivation in the CNS of Mct8/Oatp1c1 DKO mice included highly decreased brain TH content as well as altered deiodinase activities and TH target gene expression. Consistent with delayed cerebellar development and reduced myelination, Mct8/Oatp1c1 DKO mice displayed pronounced locomotor abnormalities. Intriguingly, differentiation of GABAergic interneurons in the cerebral cortex was highly compromised. Our findings underscore the importance of TH transporters for proper brain development and provide a basis to study the pathogenic mechanisms underlying AHDS.
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Müller J, Mayerl S, Visser TJ, Darras VM, Boelen A, Frappart L, Mariotta L, Verrey F, Heuer H. Tissue-specific alterations in thyroid hormone homeostasis in combined Mct10 and Mct8 deficiency. Endocrinology 2014; 155:315-25. [PMID: 24248460 DOI: 10.1210/en.2013-1800] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The monocarboxylate transporter Mct10 (Slc16a10; T-type amino acid transporter) facilitates the cellular transport of thyroid hormone (TH) and shows an overlapping expression with the well-established TH transporter Mct8. Because Mct8 deficiency is associated with distinct tissue-specific alterations in TH transport and metabolism, we speculated that Mct10 inactivation may compromise the tissue-specific TH homeostasis as well. However, analysis of Mct10 knockout (ko) mice revealed normal serum TH levels and tissue TH content in contrast to Mct8 ko mice that are characterized by high serum T3, low serum T4, decreased brain TH content, and increased tissue TH concentrations in the liver, kidneys, and thyroid gland. Surprisingly, mice deficient in both TH transporters (Mct10/Mct8 double knockout [dko] mice) showed normal serum T4 levels in the presence of elevated serum T3, indicating that the additional inactivation of Mct10 partially rescues the phenotype of Mct8 ko mice. As a consequence of the normal serum T4, brain T4 content and hypothalamic TRH expression were found to be normalized in the Mct10/Mct8 dko mice. In contrast, the hyperthyroid situation in liver, kidneys, and thyroid gland of Mct8 ko mice was even more severe in Mct10/Mct8 dko animals, suggesting that in these organs, both transporters contribute to the TH efflux. In summary, our data indicate that Mct10 indeed participates in tissue-specific TH transport and also contributes to the generation of the unusual serum TH profile characteristic for Mct8 deficiency.
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Affiliation(s)
- Julia Müller
- Leibniz Institute for Age Research/Fritz Lipmann Institute (J.M., S.M., L.F., H.H.), Jena, Germany; Department of Internal Medicine (T.J.V.), Erasmus Medical Center, Rotterdam, The Netherlands; Laboratory of Comparative Endocrinology (V.M.D.), Biology Department, Katholieke Universiteit Leuven, Leuven, Belgium; Department of Endocrinology and Metabolism (A.B.), Academic Medical Center, Amsterdam, The Netherlands; Institute of Physiology and Zürich Center for Integrative Human Physiology (L.M., F.V.), University of Zürich, Zürich, Switzerland; and Leibniz Institute for Environmental Medicine (H.H.), Düsseldorf, Germany
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Visser WE, van Mullem AAA, Visser TJ, Peeters RP. Different causes of reduced sensitivity to thyroid hormone: diagnosis and clinical management. Clin Endocrinol (Oxf) 2013; 79:595-605. [PMID: 23834164 DOI: 10.1111/cen.12281] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 06/05/2013] [Accepted: 07/01/2013] [Indexed: 11/30/2022]
Abstract
Normal thyroid hormone (TH) metabolism and action require adequate cellular TH signalling. This entails proper function of TH transporters in the plasma membrane, intracellular deiodination of TH and action of the bioactive hormone T3 at its nuclear receptors (TRs). The present review summarizes the discoveries of different syndromes with reduced sensitivity at the cellular level. Mutations in the TH transporter MCT8 cause psychomotor retardation and abnormal thyroid parameters. Mutations in the SBP2 protein, which is required for normal deiodination, give rise to a multisystem disorder including abnormal thyroid function tests. Mutations in TRβ1 are a well-known cause of resistance to TH with mostly a mild phenotype, while only recently, patients with mutations in TRα1 were identified. The latter patients have slightly abnormal TH levels, growth retardation and cognitive defects. This review will describe the mechanisms of disease, clinical phenotype, diagnostic testing and suggestions for treatment strategies for each of these syndromes.
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Affiliation(s)
- W Edward Visser
- Department of Internal Medicine, Erasmus Medical Centre, Rotterdam, The Netherlands
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Fu J, Refetoff S, Dumitrescu AM. Inherited defects of thyroid hormone-cell-membrane transport: review of recent findings. Curr Opin Endocrinol Diabetes Obes 2013; 20:434-40. [PMID: 23974772 PMCID: PMC4061907 DOI: 10.1097/01.med.0000432531.03233.ad] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW This review summarizes the most significant findings over the last year regarding human and animal models deficient in thyroid hormone cell-membrane transporters (THCMTs). Although several THCMTs have been modelled in genetically engineered mice, the only THCMT defect known in humans is that caused by mutations in the monocarboxylate transporter 8 (MCT8) gene. RECENT FINDINGS The importance of several amino acid residues has been assessed in vitro to further our understanding on the structure-function of the MCT8. The administration of the thyromimetic compound, diiodothyropropionic acid, has been tested in patients with MCT8 gene mutations, following studies of its use in mice. Another thyroid hormone analogue, 3,3',5,5'-tetraiodothyroacetic acid, was tested in Mct8-deficient mice. The phenotypes of L-type aminoacid transporter 2 and organic anion transporting polypeptide 1C1 deficiencies have been studied in mouse models. Mct8/organic anion transporting polypeptide 1C1 double knockout mice have been shown to manifest neurodevelopmental deficits. Zebrafish is emerging as another vertebrate model that may be useful to study the role of Mct8 in brain development. SUMMARY Studies on the pathogenesis and therapy of MCT8 deficiency are in progress, and new vertebrate models that are suitable to study the neurological consequences of the syndrome are being explored.
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Affiliation(s)
- Jiao Fu
- Department of Medicine, The University of Chicago, Chicago, Illinois, USA
| | - Samuel Refetoff
- Departments of Medicine, Pediatrics and Genetics, The University of Chicago, Chicago, Illinois, USA
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Ferrara AM, Liao XH, Gil-Ibáñez P, Marcinkowski T, Bernal J, Weiss RE, Dumitrescu AM, Refetoff S. Changes in thyroid status during perinatal development of MCT8-deficient male mice. Endocrinology 2013; 154:2533-41. [PMID: 23696569 PMCID: PMC3689279 DOI: 10.1210/en.2012-2031] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Patients with the monocarboxylate transporter 8 (MCT8) deficiency syndrome present with a severe psychomotor retardation and abnormal serum thyroid hormone (TH) levels, consisting of high T(3) and low T(4) and rT(3). Mice deficient in Mct8 replicate the thyroid phenotype of patients with the MCT8 gene mutations. We analyzed the serum TH levels and action in the cerebral cortex and in the liver during the perinatal period of mice deficient in Mct8 to assess how the thyroid abnormalities of Mct8 deficiency develop and to study the thyroidal status of specific tissues. During perinatal life, the thyroid phenotype of Mct8-deficient mice is different from that of adult mice. They manifest hyperthyroxinemia at embryonic day 18 and postnatal day 0. This perinatal hyperthyroxinemia is accompanied by manifestations of TH excess as evidenced by a relative increase in the expression of genes positively regulated by T3 in both the cerebral cortex and liver. An increased tissue accumulation of T(4) and T(3) and the expression of TH alternative transporters, including Lat1, Lat2, Oatp1c1, and Oatp3a1 in the cortex and Lat2 and Oatp1b2 in the liver, suggested that Mct8 deficiency either directly interferes with tissue efflux of TH or indirectly activates other transporters to increase TH uptake. This report is the first to identify that the ontogenesis of TH abnormalities in Mct8-deficient mice manifests with TH excess in the perinatal period.
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Vasilopoulou E, Loubière LS, Heuer H, Trajkovic-Arsic M, Darras VM, Visser TJ, Lash GE, Whitley GS, McCabe CJ, Franklyn JA, Kilby MD, Chan SY. Monocarboxylate transporter 8 modulates the viability and invasive capacity of human placental cells and fetoplacental growth in mice. PLoS One 2013; 8:e65402. [PMID: 23776477 PMCID: PMC3680392 DOI: 10.1371/journal.pone.0065402] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 04/25/2013] [Indexed: 11/22/2022] Open
Abstract
Monocarboxylate transporter 8 (MCT8) is a well-established thyroid hormone (TH) transporter. In humans, MCT8 mutations result in changes in circulating TH concentrations and X-linked severe global neurodevelopmental delay. MCT8 is expressed in the human placenta throughout gestation, with increased expression in trophoblast cells from growth-restricted pregnancies. We postulate that MCT8 plays an important role in placental development and transplacental TH transport. We investigated the effect of altering MCT8 expression in human trophoblast in vitro and in a Mct8 knockout mouse model. Silencing of endogenous MCT8 reduced T3 uptake into human extravillous trophoblast-like cells (SGHPL-4; 40%, P<0.05) and primary cytotrophoblast (15%, P<0.05). MCT8 over-expression transiently increased T3 uptake (SGHPL-4∶30%, P<0.05; cytotrophoblast: 15%, P<0.05). Silencing MCT8 did not significantly affect SGHPL-4 invasion, but with MCT8 over-expression T3 treatment promoted invasion compared with no T3 (3.3-fold; P<0.05). Furthermore, MCT8 silencing increased cytotrophoblast viability (∼20%, P<0.05) and MCT8 over-expression reduced cytotrophoblast viability independently of T3 (∼20%, P<0.05). In vivo, Mct8 knockout reduced fetal:placental weight ratios compared with wild-type controls at gestational day 18 (25%, P<0.05) but absolute fetal and placental weights were not significantly different. The volume fraction of the labyrinthine zone of the placenta, which facilitates maternal-fetal exchange, was reduced in Mct8 knockout placentae (10%, P<0.05). However, there was no effect on mouse placental cell proliferation in vivo. We conclude that MCT8 makes a significant contribution to T3 uptake into human trophoblast cells and has a role in modulating human trophoblast cell invasion and viability. In mice, Mct8 knockout has subtle effects upon fetoplacental growth and does not significantly affect placental cell viability probably due to compensatory mechanisms in vivo.
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Affiliation(s)
- Elisavet Vasilopoulou
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Laurence S. Loubière
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Heike Heuer
- Leibniz Institute for Age Research/Fritz Lipmann Institute, Jena, Germany
| | | | - Veerle M. Darras
- Laboratory of Comparative Endocrinology, Katholieke Universiteit, Leuven, Belgium
| | | | - Gendie E. Lash
- Reproductive and Vascular Biology Group, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Guy S. Whitley
- Division of Biomedical Sciences, St George’s University of London, London, United Kingdom
| | - Christopher J. McCabe
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Jayne A. Franklyn
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Mark D. Kilby
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Shiao Y. Chan
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- * E-mail:
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Castro I, Quisenberry L, Calvo RM, Obregon MJ, Lado-Abeal J. Septic shock non-thyroidal illness syndrome causes hypothyroidism and conditions for reduced sensitivity to thyroid hormone. J Mol Endocrinol 2013; 50:255-66. [PMID: 23296981 DOI: 10.1530/jme-12-0188] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Non-thyroidal illness syndrome (NTIS) is part of the neuroendocrine response to stress, but the significance of this syndrome remains uncertain. The aim of this study was to investigate the effect of lipopolysaccharide (LPS)-induced NTIS on thyroid hormone (TH) levels and TH molecular targets, as well as the relationship between septic shock nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) activation and TH receptor β (THRB) gene expression at a multi-tissue level in a pig model. Prepubertal domestic pigs were given i.v. saline or LPS for 48 h. Serum and tissue TH was measured by chemiluminescence and RIA. Expression of THRs and cofactors was measured by real-time PCR, and deiodinase (DIO) activity was measured by enzyme assays. Tissue NF-kB nuclear binding activity was evaluated by EMSA. LPS-treated pigs had decreased TH levels in serum and most tissues. DIO1 expression in liver and kidney and DIO1 activity in kidney decreased after LPS. No changes in DIO2 activity were observed between groups. LPS induced an increase in hypothalamus, thyroid, and liver DIO3 activity. Among the other studied genes, monocarboxylate transporter 8 and THRB were the most commonly repressed in endotoxemic pigs. LPS-induced NF-kB activation was associated with a decrease in THRB gene expression only in frontal lobe, adrenal gland, and kidney cortex. We conclude that LPS-induced NTIS in pigs is characterized by hypothyroidism and tissue-specific reduced TH sensitivity. The role of NF-kB in regulating THRB expression during endotoxemia, if any, is restricted to a limited number of tissues.
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Affiliation(s)
- Isabel Castro
- Division of Endocrinology, Department of Internal Medicine, Texas Tech University Health Sciences Center School of Medicine, Lubbock, Texas 79430-9410, USA
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Verge CF, Konrad D, Cohen M, Di Cosmo C, Dumitrescu AM, Marcinkowski T, Hameed S, Hamilton J, Weiss RE, Refetoff S. Diiodothyropropionic acid (DITPA) in the treatment of MCT8 deficiency. J Clin Endocrinol Metab 2012; 97:4515-23. [PMID: 22993035 PMCID: PMC3513545 DOI: 10.1210/jc.2012-2556] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Monocarboxylate transporter 8 (MCT8) is a thyroid hormone-specific cell membrane transporter. MCT8 deficiency causes severe psychomotor retardation and abnormal thyroid tests. The great majority of affected children cannot walk or talk, and all have elevated serum T(3) levels, causing peripheral tissue hypermetabolism and inability to maintain weight. Treatment with thyroid hormone is ineffective. In Mct8-deficient mice, the thyroid hormone analog, diiodothyropropionic acid (DITPA), does not require MCT8 to enter tissues and could be an effective alternative to thyroid hormone treatment in humans. OBJECTIVE The objective of the study was to evaluate the effect and efficacy of DITPA in children with MCT8 deficiency. METHODS This was a multicenter report of four affected children given DITPA on compassionate grounds for 26-40 months. Treatment was initiated at ages 8.5-25 months, beginning with a small dose of 1.8 mg, increasing to a maximal 30 mg/d (2.1-2.4 mg/kg · d), given in three divided doses. RESULTS DITPA normalized the elevated serum T(3) and TSH when the dose reached 1 mg/kg · d and T(4) and rT(3) increased to the lower normal range. The following significant changes were also observed: decline in SHBG (in all subjects), heart rate (in three of four), and ferritin (in one of four). Cholesterol increased in two subjects. There was no weight loss and weight gain occurred in two. None of the treated children required a gastric feeding tube or developed seizures. No adverse effects were observed. CONCLUSION DITPA (1-2 mg/kg · d) almost completely normalizes thyroid tests and reduces the hypermetabolism and the tendency for weight loss. The effects of earlier commencement and long-term therapy remain to be determined.
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Affiliation(s)
- Charles F Verge
- Department of Endocrinology, Sydney Children's Hospital, Randwick, NSW 2031, Australia
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Smith VE, Read ML, Turnell AS, Sharma N, Lewy GD, Fong JCW, Seed RI, Kwan P, Ryan G, Mehanna H, Chan SY, Darras VM, Boelaert K, Franklyn JA, McCabe CJ. PTTG-binding factor (PBF) is a novel regulator of the thyroid hormone transporter MCT8. Endocrinology 2012; 153:3526-36. [PMID: 22535767 DOI: 10.1210/en.2011-2030] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Within the basolateral membrane of thyroid follicular epithelial cells, two transporter proteins are central to thyroid hormone (TH) biosynthesis and secretion. The sodium iodide symporter (NIS) delivers iodide from the bloodstream into the thyroid, and after TH biosynthesis, monocarboxylate transporter 8 (MCT8) mediates TH secretion from the thyroid gland. Pituitary tumor-transforming gene-binding factor (PBF; PTTG1IP) is a protooncogene that is up-regulated in thyroid cancer and that binds NIS and modulates its subcellular localization and function. We now show that PBF binds MCT8 in vitro, eliciting a marked shift in MCT8 subcellular localization and resulting in a significant reduction in the amount of MCT8 at the plasma membrane as determined by cell surface biotinylation assays. Colocalization and interaction between PBF and Mct8 was also observed in vivo in a mouse model of thyroid-specific PBF overexpression driven by a bovine thyroglobulin (Tg) promoter (PBF-Tg). Thyroidal Mct8 mRNA and protein expression levels were similar to wild-type mice. Critically, however, PBF-Tg mice demonstrated significantly enhanced thyroidal TH accumulation and reduced TH secretion upon TSH stimulation. Importantly, Mct8-knockout mice share this phenotype. These data show that PBF binds and alters the subcellular localization of MCT8 in vitro, with PBF overexpression leading to an accumulation of TH within the thyroid in vivo. Overall, these studies identify PBF as the first protein to interact with the critical TH transporter MCT8 and modulate its function in vivo. Furthermore, alongside NIS repression, PBF may thus represent a new regulator of TH biosynthesis and secretion.
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Affiliation(s)
- V E Smith
- School of Clinical and Experimental Medicine, Institute for Biomedical Research, University of Birmingham, Birmingham, B15 2TT, United Kingdom
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Müller J, Heuer H. Understanding the hypothalamus-pituitary-thyroid axis in mct8 deficiency. Eur Thyroid J 2012; 1:72-9. [PMID: 24783000 PMCID: PMC3821472 DOI: 10.1159/000339474] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 05/15/2012] [Indexed: 11/19/2022] Open
Abstract
Thyroid hormone (TH) metabolism and action via binding to nuclear receptors are intracellular events that require the passage of TH across the plasma membrane. This process is mediated by specific TH transporters of which the monocarboxylate transporter 8 (Mct8) has received major attention. Mct8 is highly expressed in different tissues such as liver, kidney, thyroid, pituitary and brain. In humans, inactivating mutations of the MCT8 gene (SLC16A2) are associated with severe forms of psychomotor retardation and abnormal TH serum levels (Allan-Herndon-Dudley syndrome). Surprisingly, Mct8 knockout (ko) mice do not exhibit overt neurological symptoms but fully replicate the unusual serum TH profile with highly increased serum T3 in the presence of low serum T4. In order to evaluate the underlying mechanisms for these abnormalities, TH transport and metabolism have been intensively studied in different tissues of Mct8 ko mice. Here, we summarize the observed changes within the hypothalamus-pituitary-thyroid axis that result in altered TH production and secretion. Although analysis of Mct8 ko mice has greatly expanded our knowledge, many open questions still remain to be addressed in order to define the tissue- and cell-specific role of this important TH transporter.
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Affiliation(s)
| | - Heike Heuer
- *Heike Heuer, PhD, Leibniz Institute for Age Research/Fritz Lipmann Institute e.V., Beutenbergstrasse 11, DE–07745 Jena (Germany), Tel. +49 3641 65 6021, E-Mail
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Heuer H, Visser TJ. The pathophysiological consequences of thyroid hormone transporter deficiencies: Insights from mouse models. Biochim Biophys Acta Gen Subj 2012; 1830:3974-8. [PMID: 22543196 DOI: 10.1016/j.bbagen.2012.04.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 04/04/2012] [Accepted: 04/11/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND As a prerequisite for thyroid hormone (TH) metabolism and action TH has to be transported into cells where TH deiodinases and receptors are located. The trans-membrane passage of TH is facilitated by TH transporters of which the monocarboxylate transporter MCT8 has been most intensively studied. Inactivating mutations in the gene encoding MCT8 are associated with a severe form of psychomotor retardation and abnormal serum TH levels (Allan-Herndon-Dudley syndrome). In order to define the underlying pathogenic mechanisms, Mct8 knockout mice have been generated and intensively studied. Most surprisingly, Mct8 ko mice do not show any neurological symptoms but fully replicate the abnormal serum thyroid state. SCOPE OF REVIEW We will summarize the findings of these mouse studies that shed light on various aspects of Mct8 deficiency and unambiguously demonstrated the pivotal role of Mct8 in mediating TH transport in various tissues. These studies have also revealed the presence of the complex interplay between different pathogenic mechanisms that contribute to the generation of the abnormal TH serum profile. MAJOR CONCLUSIONS Most importantly, studies of Mct8 ko mice indicated the presence of additional TH transporters that act in concert with Mct8. Interesting candidates for such a function are the L-type amino acid transporters Lat1 and Lat2 as well as the organic anion transporting polypeptide Oatp1c1. GENERAL SIGNIFICANCE Overall, the analysis of Mct8 deficient mice has greatly expanded our knowledge about the (patho-) physiological function of this transporter and established a sound basis for the characterization of additional TH transporter candidates. This article is part of a Special Issue entitled Thyroid hormone signalling.
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Affiliation(s)
- Heike Heuer
- Leibniz Institute for Age Research/Fritz Lipmann Institute, Jena, Germany.
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Mayerl S, Visser TJ, Darras VM, Horn S, Heuer H. Impact of Oatp1c1 deficiency on thyroid hormone metabolism and action in the mouse brain. Endocrinology 2012; 153:1528-37. [PMID: 22294745 DOI: 10.1210/en.2011-1633] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Organic anion-transporting polypeptide 1c1 (Oatp1c1) (also known as Slco1c1 and Oatp14) belongs to the family of Oatp and has been shown to facilitate the transport of T(4). In the rodent brain, Oatp1c1 is highly enriched in capillary endothelial cells and choroid plexus structures where it may mediate the entry of T(4) into the central nervous system. Here, we describe the generation and first analysis of Oatp1c1-deficient mice. Oatp1c1 knockout (KO) mice were born with the expected frequency, were not growth retarded, and developed without any overt neurological abnormalities. Serum T(3) and T(4) concentrations as well as renal and hepatic deiodinase type 1 expression levels were indistinguishable between Oatp1c1 KO mice and control animals. Hypothalamic TRH and pituitary TSH mRNA levels were not affected, but brain T(4) and T(3) content was decreased in Oatp1c1-deficient animals. Moreover, increased type 2 and decreased type 3 deiodinase activities indicate a mild hypothyroid situation in the brain of Oatp1c1 KO mice. Consequently, mRNA expression levels of gene products positively regulated by T(3) in the brain were down-regulated. This central nervous system-specific hypothyroidism is presumably caused by an impaired passage of T(4) across the blood-brain barrier and indicates a unique function of Oatp1c1 in facilitating T(4) transport despite the presence of other thyroid hormone transporters such as Mct8.
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Affiliation(s)
- Steffen Mayerl
- Leibniz Institute for Age Research/Fritz Lipmann Institute e.V., Beutenbergstrasse 11, D-07745 Jena/Germany
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Abstract
BACKGROUND Previous studies have shown that thyroxine (T4) is stored as T4 glucuronide (T4G) in the kidney, and that 24 hours after administration of [(125)I]T4 to mice, 17% of the radioactivity was present in the kidneys, whereas only 4% was found in the liver. The present study was carried out to determine the relative amounts of conjugated and unconjugated T4 and 3,5,3'-triiodothyronine (T3) in the kidney and liver, and whether the conjugated hormones are extracted from tissues using our established extraction protocols, and detected in our radioimmunoassays (RIAs) for T4 and T3. METHODS Mice were injected with 10 μCi [(125)I]T4 or [(125)I]T3 and 24 hours later, the labeled compounds present in serum, kidney, liver, and urine were extracted and analyzed by paper chromatography before and after treatment with β-glucuronidase. In addition, the amounts of endogenous T4 and T3 in extracts of mouse kidney and liver were measured by RIA before and after treatment with β-glucuronidase. RESULTS After [(125)I]T4, more than 95% of the total kidney and liver radioactivity was extracted, and in the kidney, almost all of it was present in a conjugated form, mostly as T4G. The liver also contained T4G, but none was present in serum or urine. T3 glucuronide (T3G) was also found in the kidney and liver after the administration of [(125)I]T3. Analysis by RIA of the endogenous T4 content in extracts of kidney before and after hydrolysis by β-glucuronidase revealed that a substantial fraction of the T4 in both tissues was present as T4G, and the T4G was not detected in the RIA. Furthermore, the combined T4+T4G content in the kidney expressed per gram of tissue was significantly higher than that in the liver or serum. In contrast, the kidney content of T3+T3G was very low compared with that of T4+T4G. CONCLUSIONS In summary, we have shown that the kidney stores a significant amount of T4 as T4G. Since T4G deconjugation can occur rapidly in the kidney, it is possible that this tissue participates in maintaining extrathyroidal serum T4 homeostasis.
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Affiliation(s)
- Maarten Buitendijk
- Department of Physiology and Neurobiology, Dartmouth Medical School, Lebanon, New Hampshire 03756, USA
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Arjona FJ, de Vrieze E, Visser TJ, Flik G, Klaren PHM. Identification and functional characterization of zebrafish solute carrier Slc16a2 (Mct8) as a thyroid hormone membrane transporter. Endocrinology 2011; 152:5065-73. [PMID: 21952246 DOI: 10.1210/en.2011-1166] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Most components of the thyroid system in bony fish have been described and characterized, with the notable exception of thyroid hormone membrane transporters. We have cloned, sequenced, and expressed the zebrafish solute carrier Slc16a2 (also named monocarboxylate transporter Mct8) cDNA and established its role as a thyroid hormone transport protein. The cloned cDNA shares 56-57% homology with its mammalian orthologs. The 526-amino-acid sequence contains 12 predicted transmembrane domains. An intracellular N-terminal PEST domain, thought to be involved in proteolytic processing of the protein, is present in the zebrafish sequence. Measured at initial rate and at the body/rearing temperature of zebrafish (26 C), T(3) uptake by zebrafish Slc16a2 is a saturable process with a calculated Michaelis-Menten constant of 0.8 μM T(3). The rate of T(3) uptake is temperature dependent and Na(+) independent. Interestingly, at 26 C, zebrafish Slc16a2 does not transport T(4). This implies that at a normal body temperature in zebrafish, Slc16a2 protein is predominantly involved in T(3) uptake. When measured at 37 C, zebrafish Slc16a2 transports T(4) in a Na(+)-independent manner. In adult zebrafish, the Slc16a2 gene is highly expressed in brain, gills, pancreas, liver, pituitary, heart, kidney, and gut. Beginning from the midblastula stage, Slc16a2 is also expressed during zebrafish early development, the highest expression levels occurring 48 h after fertilization. This is the first direct evidence for thyroid hormone membrane transporters in fish. We suggest that Slc16a2 plays a key role in the local availability of T(3) in adult tissues as well as during the completion of morphogenesis of primary organ systems.
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Affiliation(s)
- Francisco J Arjona
- Department of Organismal Animal Physiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
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Aminoaciduria, but normal thyroid hormone levels and signalling, in mice lacking the amino acid and thyroid hormone transporter Slc7a8. Biochem J 2011; 439:249-55. [PMID: 21726201 DOI: 10.1042/bj20110759] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
LAT2 (system L amino acid transporter 2) is composed of the subunits Slc7a8/Lat2 and Slc3a2/4F2hc. This transporter is highly expressed along the basolateral membranes of absorptive epithelia in kidney and small intestine, but is also abundant in the brain. Lat2 is an energy-independent exchanger of neutral amino acids, and was shown to transport thyroid hormones. We report in the present paper that targeted inactivation of Slc7a8 leads to increased urinary loss of small neutral amino acids. Development and growth of Slc7a8(-/-) mice appears normal, suggesting functional compensation of neutral amino acid transport by alternative transporters in kidney, intestine and placenta. Movement co-ordination is slightly impaired in mutant mice, although cerebellar development and structure remained inconspicuous. Circulating thyroid hormones, thyrotropin and thyroid hormone-responsive genes remained unchanged in Slc7a8(-/-) mice, possibly because of functional compensation by the thyroid hormone transporter Mct8 (monocarboxylate transporter 8), which is co-expressed in many cell types. The reason for the mild neurological phenotype remains unresolved.
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Abstract
PURPOSE OF REVIEW To discuss the recent advances on thyroid hormone transport in the brain. A special attention is paid to the X-linked thyroid hormone cell transport (THCT) defect (also known as the Allan-Herndon-Dudley syndrome), caused by mutations of the specific thyroid hormone transporter MCT8 gene. RECENT FINDINGS MCT8 is involved in thyroid hormone transport in the brain. MRI of patients with THCT defect showed myelination delays, probably related to impaired thyroid hormone action on oligodendrocytes. MCT8 is also expressed in the thyroid and has an important role in thyroid hormone secretion. The altered circulating concentrations of thyroid hormone in the patients are partly because of impaired secretion and altered peripheral metabolism. Increased deiodinase activity is important in the pathophysiology of the syndrome. High D1 activity in liver and kidney increases T4 and rT3 deiodination, and contributes to the increased serum T3. High D2 activity in the brain contributes to compensate the deficient T3 transport by increasing local T3 production. SUMMARY Patients with suspected X-linked leukoencephalopathy should be screened for MCT8 gene mutations. Research on the brain pathophysiology of the THCT defect should focus on the specific role of Mct8 on oligodendrocytes and myelination.
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Affiliation(s)
- Juan Bernal
- Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.
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Kersseboom S, Visser TJ. MCT8: from gene to disease and therapeutic approach. ANNALES D'ENDOCRINOLOGIE 2011; 72:77-81. [PMID: 21511238 DOI: 10.1016/j.ando.2011.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Thyroid hormone metabolism and action are largely intracellular processes that require transport of the hormone across the plasma membrane by different transporters. Two of these, MCT8 and MCT10, are close members of the monocarboxylate transporter family. MCT8 is expressed in a variety of tissues, including liver, kidney, thyroid and brain. The MCT8 gene is located on the X chromosome, and mutations in MCT8 result in severe psychomotor retardation and low serum T4 and high T3 levels in affected males. The psychomotor retardation is thought to be caused by impaired neuronal T3 uptake during brain development. The abnormal thyroid hormone levels appear to result from an increased T4 to T3 conversion in the kidney as well as altered hormone secretion from the thyroid gland. Options for therapy aim at early treatment with T3 analogues, neuronal uptake of which does not require MCT8.
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Affiliation(s)
- S Kersseboom
- Department of Internal Medicine, Erasmus MC, CA, Rotterdam, The Netherlands
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Liao XH, Di Cosmo C, Dumitrescu AM, Hernandez A, Van Sande J, St Germain DL, Weiss RE, Galton VA, Refetoff S. Distinct roles of deiodinases on the phenotype of Mct8 defect: a comparison of eight different mouse genotypes. Endocrinology 2011; 152:1180-91. [PMID: 21285310 PMCID: PMC3040057 DOI: 10.1210/en.2010-0900] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mice deficient in the thyroid hormone (TH) transporter Mct8 (Mct8KO) have increased 5'-deiodination and impaired TH secretion and excretion. These and other unknown mechanisms result in the low-serum T(4), high T(3), and low rT(3) levels characteristic of Mct8 defects. We investigated to what extent each of the 5'-deiodinases (D1, D2) contributes to the serum TH abnormalities of the Mct8KO by generating mice with all combinations of Mct8 and D1 and/or D2 deficiencies and comparing the resulting eight genotypes. Adding D1 deficiency to that of Mct8 corrected the serum TH abnormalities of Mct8KO mice, normalized brain T(3) content, and reduced the impaired expression of TH-responsive genes. In contrast, Mct8D2KO mice maintained the serum TH abnormalities of Mct8KO mice. However, the serum TSH level increased 27-fold, suggesting a severely impaired hypothalamo-pituitary-thyroid axis. The brain of Mct8D2KO manifested a pattern of more severe impairment of TH action than Mct8KO alone. In triple Mct8D1D2KO mice, the markedly increased serum TH levels produced milder brain defect than that of Mct8D2KO at the expense of more severe liver thyrotoxicosis. Additionally, we observed that mice deficient in D2 had an unexplained marked reduction in the thyroid growth response to TSH. Our studies on these eight genotypes provide a unique insight into the complex interplay of the deiodinases in the Mct8 defect and suggest that D1 contributes to the increased serum T(3) in Mct8 deficiency, whereas D2 mainly functions locally, converting T(4) to T(3) to compensate for distinct cellular TH depletion in Mct8KO mice.
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Affiliation(s)
- Xiao-Hui Liao
- Department of Medicine, The University of Chicago, MC3090, 5841 South Maryland Avenue, Chicago, Illinois 60637, USA
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Kersseboom S, Visser TJ. Tissue-specific effects of mutations in the thyroid hormone transporter MCT8. ACTA ACUST UNITED AC 2011; 55:1-5. [DOI: 10.1590/s0004-27302011000100001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Trajkovic-Arsic M, Müller J, Darras VM, Groba C, Lee S, Weih D, Bauer K, Visser TJ, Heuer H. Impact of monocarboxylate transporter-8 deficiency on the hypothalamus-pituitary-thyroid axis in mice. Endocrinology 2010; 151:5053-62. [PMID: 20702572 DOI: 10.1210/en.2010-0593] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In patients, inactivating mutations in the gene encoding the thyroid hormone-transporting monocarboxylate transporter 8 (Mct8) are associated with severe mental and neurological deficits and disturbed thyroid hormone levels. The latter phenotype characterized by high T3 and low T4 serum concentrations is replicated in Mct8 knockout (ko) mice, indicating that MCT8 deficiency interferes with thyroid hormone production and/or metabolism. Our studies of Mct8 ko mice indeed revealed increased thyroidal T3 and T4 concentrations without overt signs of a hyperactive thyroid gland. However, upon TSH stimulation Mct8 ko mice showed decreased T4 and increased T3 secretion compared with wild-type littermates. Moreover, similar changes in the thyroid hormone secretion pattern were observed in Mct8/Trhr1 double-ko mice, which are characterized by normal serum T3 levels and normal hepatic and renal D1 expression in the presence of very low T4 serum concentrations. These data strongly indicate that absence of Mct8 in the thyroid gland affects thyroid hormone efflux by shifting the ratio of the secreted hormones toward T3. To test this hypothesis, we generated Mct8/Pax8 double-mutant mice, which in addition to Mct8 lack a functional thyroid gland and are therefore completely athyroid. Following the injection of these animals with either T4 or T3, serum analysis revealed T3 concentrations similar to those observed in Pax8 ko mice under thyroid hormone replacement, indicating that indeed increased thyroidal T3 secretion in Mct8 ko mice represents an important pathogenic mechanism leading to the high serum T3 levels.
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Affiliation(s)
- Marija Trajkovic-Arsic
- Leibniz Institute for Age Research/Fritz Lipmann Institute e.V., Beutenbergstr. 11, D-07745 Jena, Germany
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Visser WE, Friesema ECH, Visser TJ. Minireview: thyroid hormone transporters: the knowns and the unknowns. Mol Endocrinol 2010; 25:1-14. [PMID: 20660303 DOI: 10.1210/me.2010-0095] [Citation(s) in RCA: 266] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The effects of thyroid hormone (TH) on development and metabolism are exerted at the cellular level. Metabolism and action of TH take place intracellularly, which require transport of the hormone across the plasma membrane. This process is mediated by TH transporter proteins. Many TH transporters have been identified at the molecular level, although a few are classified as specific TH transporters, including monocarboxylate transporter (MCT)8, MCT10, and organic anion-transporting polypeptide 1C1. The importance of TH transporters for physiology has been illustrated dramatically by the causative role of MCT8 mutations in males with psychomotor retardation and abnormal serum TH concentrations. Although Mct8 knockout animals have provided insight in the mechanisms underlying parts of the endocrine phenotype, they lack obvious neurological abnormalities. Thus, the pathogenesis of the neurological abnormalities in males with MCT8 mutations is not fully understood. The prospects of identifying other transporters and transporter-based syndromes promise an exciting future in the TH transporter field.
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Affiliation(s)
- W Edward Visser
- Erasmus University Medical Center, Molewaterplein 50, Rotterdam, The Netherlands
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