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Grunenwald S, Caron P. Key data from the 2023 European Thyroid Association annual meeting: Thyroid hormone resistance syndromes. ANNALES D'ENDOCRINOLOGIE 2024; 85:161-162. [PMID: 38365508 DOI: 10.1016/j.ando.2024.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/18/2024]
Affiliation(s)
- Solange Grunenwald
- Department of Endocrinology, Metabolic Diseases and Nutrition, Cardiovascular and Metabolic Unit, CHU Larrey, Toulouse, France
| | - Philippe Caron
- Department of Endocrinology, Metabolic Diseases and Nutrition, Cardiovascular and Metabolic Unit, CHU Larrey, Toulouse, France.
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2
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Grijota-Martínez C, Montero-Pedrazuela A, Hidalgo-Álvarez J, Bárez-López S, Guadaño-Ferraz A. Intracerebroventricular High Doses of 3,3',5-Triiodothyroacetic Acid at Juvenile Stages Improve Peripheral Hyperthyroidism and Mediate Thyromimetic Effects in Limited Brain Regions in a Mouse Model of Monocarboxylate Transporter 8 Deficiency. Thyroid 2023; 33:501-510. [PMID: 36565029 DOI: 10.1089/thy.2022.0562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Introduction: Patients lacking functional monocarboxylate transporter 8 (MCT8), a highly specific thyroid hormone (TH) transporter, present severe psychomotor disabilities. MCT8 deficiency leads to peripheral hyperthyroidism and brain hypothyroidism, the latter due to impaired transport of TH across brain barriers. Available treatments for patients are limited and aim to overcome the limited TH transport across brain barriers. The use of TH analogues such as 3,3',5-triiodothyroacetic acid (TRIAC) that do not require MCT8 to cross the cellular membranes is considered a potential therapy for MCT8 deficiency. Previous studies have shown that systemic administration of TRIAC at therapeutic doses does not increase TRIAC content in the brain, while intracerebroventricular (ICV) administration of therapeutic doses of TRIAC increases TRIAC content in the brain but does not mediate thyromimetic effects. In view of this, we hypothesize that ICV administration of high doses of TRIAC can mediate thyromimetic effects in the brain without worsening the brain hypothyroidism or peripheral hyperthyroidism of patients. Methods: We administered 400 ng/g of body weight per day of ICV TRIAC in a mouse model of MCT8 deficiency: Mct8-/y and deiodinase 2 (Dio2)-/- double knockout mice. The effects of this treatment on TH and TRIAC levels/content in blood and tissues were determined by radioimmunoassay and effects on TH-regulated genes were assessed by real time-quantitative polymerase chain reaction in peripheral and central tissues. Results: ICV administration of high doses of TRIAC ameliorated the peripheral hyperthyroidism. In the brain, this treatment did not further aggravate brain hypothyroidism and increased TRIAC content in several brain regions; however, only moderate thyromimetic activity was observed in restricted brain areas. Conclusion: Administration of high doses of TRIAC by ICV delivery at juvenile stages in a mouse model of MCT8 deficiency is effective in normalizing peripheral hyperthyroidism but exerts minimal thyromimetic activity in the brain.
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Affiliation(s)
- Carmen Grijota-Martínez
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, Madrid, Spain
| | - Ana Montero-Pedrazuela
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Jorge Hidalgo-Álvarez
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Soledad Bárez-López
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Ana Guadaño-Ferraz
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), Madrid, Spain
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van Geest FS, Groeneweg S, Visser WE. Monocarboxylate transporter 8 deficiency: update on clinical characteristics and treatment. Endocrine 2021; 71:689-695. [PMID: 33650046 PMCID: PMC8016746 DOI: 10.1007/s12020-020-02603-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 12/28/2020] [Indexed: 11/24/2022]
Abstract
Defective thyroid hormone transport due to deficiency in thyroid hormone transporter monocarboxylate transporter 8 (MCT8) results in severe neurodevelopmental delay due to cerebral hypothyroidism and in clinical negative sequelae following a chronic thyrotoxic state in peripheral tissues. The life expectancy of patients with MCT8 deficiency is severely impaired. Increased mortality is associated with lack of head control and being underweight at young age. Treatment options are available to alleviate the thyrotoxic state; particularly, treatment with the thyroid hormone analogue triiodothyroacetic acid seems a promising therapy. This review provides an overview of key clinical features and treatment options available and under development for this rare disorder.
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Affiliation(s)
- Ferdy S van Geest
- Academic Center For Thyroid Disease, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Stefan Groeneweg
- Academic Center For Thyroid Disease, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - W Edward Visser
- Academic Center For Thyroid Disease, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands.
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van Geest FS, Meima ME, Stuurman KE, Wolf NI, van der Knaap MS, Lorea CF, Poswar FO, Vairo F, Brunetti-Pierri N, Cappuccio G, Bakhtiani P, de Munnik SA, Peeters RP, Visser WE, Groeneweg S. Clinical and Functional Consequences of C-Terminal Variants in MCT8: A Case Series. J Clin Endocrinol Metab 2021; 106:539-553. [PMID: 33141165 PMCID: PMC7823235 DOI: 10.1210/clinem/dgaa795] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Indexed: 12/17/2022]
Abstract
CONTEXT Genetic variants in SLC16A2, encoding the thyroid hormone transporter MCT8, can cause intellectual and motor disability and abnormal serum thyroid function tests, known as MCT8 deficiency. The C-terminal domain of MCT8 is poorly conserved, which complicates prediction of the deleteriousness of variants in this region. We studied the functional consequences of 5 novel variants within this domain and their relation to the clinical phenotypes. METHODS We enrolled male subjects with intellectual disability in whom genetic variants were identified in exon 6 of SLC16A2. The impact of identified variants was evaluated in transiently transfected cell lines and patient-derived fibroblasts. RESULTS Seven individuals from 5 families harbored potentially deleterious variants affecting the C-terminal domain of MCT8. Two boys with clinical features considered atypical for MCT8 deficiency had a missense variant [c.1724A>G;p.(His575Arg) or c.1796A>G;p.(Asn599Ser)] that did not affect MCT8 function in transfected cells or patient-derived fibroblasts, challenging a causal relationship. Two brothers with classical MCT8 deficiency had a truncating c.1695delT;p.(Val566*) variant that completely inactivated MCT8 in vitro. The 3 other boys had relatively less-severe clinical features and harbored frameshift variants that elongate the MCT8 protein [c.1805delT;p.(Leu602HisfsTer680) and c.del1826-1835;p.(Pro609GlnfsTer676)] and retained ~50% residual activity. Additional truncating variants within transmembrane domain 12 were fully inactivating, whereas those within the intracellular C-terminal tail were tolerated. CONCLUSIONS Variants affecting the intracellular C-terminal tail of MCT8 are likely benign unless they cause frameshifts that elongate the MCT8 protein. These findings provide clinical guidance in the assessment of the pathogenicity of variants within the C-terminal domain of MCT8.
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Affiliation(s)
- Ferdy S van Geest
- Academic Center For Thyroid Disease, Department of Internal Medicine, Erasmus Medical Center, GD Rotterdam, The Netherlands
| | - Marcel E Meima
- Academic Center For Thyroid Disease, Department of Internal Medicine, Erasmus Medical Center, GD Rotterdam, The Netherlands
| | - Kyra E Stuurman
- Department of Clinical Genetics, Erasmus Medical Center, GD Rotterdam, The Netherlands
| | - Nicole I Wolf
- Department of Pediatric Neurology, Emma Children’s Hospital, Amsterdam University Medical Centre, AZ Amsterdam, Netherlands
- Amsterdam Neuroscience, HV Amsterdam, Netherlands
| | - Marjo S van der Knaap
- Department of Pediatric Neurology, Emma Children’s Hospital, Amsterdam University Medical Centre, AZ Amsterdam, Netherlands
- Amsterdam Neuroscience, HV Amsterdam, Netherlands
| | - Cláudia F Lorea
- Teaching Hospital of Universidade Federal de Pelotas, Brazil
| | - Fabiano O Poswar
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Filippo Vairo
- Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota, USA
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Nicola Brunetti-Pierri
- Department of Translational Medicine, Federico II University, Naples, Italy
- Telethon Institute of Genetics and Medicine, Pozzuoli, Naples, Italy
| | - Gerarda Cappuccio
- Department of Translational Medicine, Federico II University, Naples, Italy
- Telethon Institute of Genetics and Medicine, Pozzuoli, Naples, Italy
| | | | - Sonja A de Munnik
- Department of Human Genetics, Radboud University Medical Centre Nijmegen, GA Nijmegen, the Netherlands
| | - Robin P Peeters
- Academic Center For Thyroid Disease, Department of Internal Medicine, Erasmus Medical Center, GD Rotterdam, The Netherlands
| | - W Edward Visser
- Academic Center For Thyroid Disease, Department of Internal Medicine, Erasmus Medical Center, GD Rotterdam, The Netherlands
| | - Stefan Groeneweg
- Academic Center For Thyroid Disease, Department of Internal Medicine, Erasmus Medical Center, GD Rotterdam, The Netherlands
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van Geest FS, Gunhanlar N, Groeneweg S, Visser WE. Monocarboxylate Transporter 8 Deficiency: From Pathophysiological Understanding to Therapy Development. Front Endocrinol (Lausanne) 2021; 12:723750. [PMID: 34539576 PMCID: PMC8440930 DOI: 10.3389/fendo.2021.723750] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 08/13/2021] [Indexed: 01/18/2023] Open
Abstract
Genetic defects in the thyroid hormone transporter monocarboxylate transporter 8 (MCT8) result in MCT8 deficiency. This disorder is characterized by a combination of severe intellectual and motor disability, caused by decreased cerebral thyroid hormone signalling, and a chronic thyrotoxic state in peripheral tissues, caused by exposure to elevated serum T3 concentrations. In particular, MCT8 plays a crucial role in the transport of thyroid hormone across the blood-brain-barrier. The life expectancy of patients with MCT8 deficiency is strongly impaired. Absence of head control and being underweight at a young age, which are considered proxies of the severity of the neurocognitive and peripheral phenotype, respectively, are associated with higher mortality rate. The thyroid hormone analogue triiodothyroacetic acid is able to effectively and safely ameliorate the peripheral thyrotoxicosis; its effect on the neurocognitive phenotype is currently under investigation. Other possible therapies are at a pre-clinical stage. This review provides an overview of the current understanding of the physiological role of MCT8 and the pathophysiology, key clinical characteristics and developing treatment options for MCT8 deficiency.
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Braun D, Schweizer U. The Protein Translocation Defect of MCT8 L291R Is Rescued by Sodium Phenylbutyrate. Eur Thyroid J 2020; 9:269-280. [PMID: 33088796 PMCID: PMC7548921 DOI: 10.1159/000507439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/24/2020] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION The monocarboxylate transporter 8 (MCT8; SLC16A2) is a specific transporter for thyroid hormones. MCT8 deficiency, formerly known as the Allan-Herndon-Dudley syndrome, is a rare genetic disease that leads to neurological impairments and muscle weakness. Current experimental treatment options rely on thyromimetic agonists that do not depend on MCT8 for cellular uptake. Another approach comes from studies with the chemical chaperone sodium phenylbutyrate (NaPB), which was able to stabilize MCT8 mutants having protein folding defects in vitro. In addition, NaPB is known as a compound that assists with plasma membrane translocation. OBJECTIVE The pathogenic MCT8L291R leads to the same severe neurological impairments found for other MCT8-deficient patients but, unexpectedly, lacks alterations in plasma 3,3',5-triiodothyronine (T3) levels. Here we tried to unravel the underlying mechanism of MCT8 deficiency and tested whether the pathogenic MCT8L291R mutant responds to NaPB treatment. Therefore, we overexpressed the mutant in Madin-Darby canine kidney cells in the human choriocarcinoma cell line JEG1 and in COS7 cells of African green monkey origin. RESULTS In our recent study we describe that the MCT8L291R mutation most likely leads to a translocation defect. The pathogenic mutant is not located at the plasma membrane, but shows overlapping expression with a marker protein of the lysosome. Mutation of the corresponding amino acid in murine Mct8 (Mct8L223R) displays a similar effect on cell surface expression and transport function as seen before for MCT8L291R. NaPB was able to correct the translocation defect of MCT8L291R/Mct8L223R and restored protein function by increasing T3 transport activity. Furthermore, we detected enhanced mRNA levels of wild-type and mutant MCT8/Mct8 after NaPB treatment. The increase in mRNA levels could be an explanation for the positive effect on protein expression and function detected for wild-type MCT8. CONCLUSION NaPB is not only suitable for the treatment of mutations leading to misfolding and protein degradation, but also for a mutant wrongly sorted inside a cell which is otherwise functional.
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Affiliation(s)
- Doreen Braun
- *Doreen Braun, Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 11, DE–53115 Bonn (Germany),
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Grijota-Martínez C, Bárez-López S, Gómez-Andrés D, Guadaño-Ferraz A. MCT8 Deficiency: The Road to Therapies for a Rare Disease. Front Neurosci 2020; 14:380. [PMID: 32410949 PMCID: PMC7198743 DOI: 10.3389/fnins.2020.00380] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 03/27/2020] [Indexed: 12/17/2022] Open
Abstract
Allan-Herndon-Dudley syndrome is a rare disease caused by inactivating mutations in the SLC16A2 gene, which encodes the monocarboxylate transporter 8 (MCT8), a transmembrane transporter specific for thyroid hormones (T3 and T4). Lack of MCT8 function produces serious neurological disturbances, most likely due to impaired transport of thyroid hormones across brain barriers during development resulting in severe brain hypothyroidism. Patients also suffer from thyrotoxicity in other organs due to the presence of a high concentration of T3 in the serum. An effective therapeutic strategy should restore thyroid hormone serum levels (both T3 and T4) and should address MCT8 transporter deficiency in brain barriers and neural cells, to enable the access of thyroid hormones to target neural cells. Unfortunately, targeted therapeutic options are currently scarce and their effect is limited to an improvement in the thyrotoxic state, with no sign of any neurological improvement. The use of thyroid hormone analogs such as TRIAC, DITPA, or sobetirome, that do not require MCT8 to cross cell membranes and whose controlled thyromimetic activity could potentially restore the normal function of the affected organs, are being explored to improve the cerebral availability of these analogs. Other strategies aiming to restore the transport of THs through MCT8 at the brain barriers and the cellular membranes include gene replacement therapy and the use of pharmacological chaperones. The design of an appropriate therapeutic strategy in combination with an early diagnosis (at prenatal stages), will be key aspects to improve the devastating alterations present in these patients.
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Affiliation(s)
- Carmen Grijota-Martínez
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Center for Biomedical Research on Rare Diseases (Ciberer), Instituto de Salud Carlos III, Madrid, Spain.,Department of Cell Biology, Faculty of Biology, Universidad Complutense de Madrid, Madrid, Spain
| | - Soledad Bárez-López
- Center for Biomedical Research on Rare Diseases (Ciberer), Instituto de Salud Carlos III, Madrid, Spain.,Translational Health Sciences, Dorothy Hodgkin Building, University of Bristol, Bristol, United Kingdom
| | - David Gómez-Andrés
- Pediatric Neurology, Vall d'Hebron University Hospital and VHIR (Euro-NMD, ERN-RND), Barcelona, Spain
| | - Ana Guadaño-Ferraz
- Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Center for Biomedical Research on Rare Diseases (Ciberer), Instituto de Salud Carlos III, Madrid, Spain
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8
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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: 102] [Impact Index Per Article: 25.5] [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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Masnada S, Groenweg S, Saletti V, Chiapparini L, Castellotti B, Salsano E, Visser WE, Tonduti D. Novel mutations in SLC16A2 associated with a less severe phenotype of MCT8 deficiency. Metab Brain Dis 2019; 34:1565-1575. [PMID: 31332729 DOI: 10.1007/s11011-019-00464-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/08/2019] [Indexed: 02/08/2023]
Abstract
Mutations in the thyroid hormone transporter MCT8 cause severe intellectual and motor disability and abnormal serum thyroid function tests, a syndrome known as MCT8 deficiency (or: Allan-Herndon-Dudley syndrome, AHDS). Although the majority of patients are unable to sit or walk independently and do not develop any speech, some are able to walk and talk in simple sentences. Here, we report on two cases with such a less severe clinical phenotype and consequent gross delay in diagnosis. Genetic analyses revealed two novel hemizygous mutations in the SLC16A2 gene resulting in a p.Thr239Pro and a p.Leu543Pro substitution in the MCT8 protein. In vitro studies in transiently transfected COS-1 and JEG-3 cells, and ex vivo studies in patient-derived fibroblasts revealed substantial residual uptake capacity of both mutant proteins (Leu543Pro > Thr239Pro), providing an explanation for the less severe clinical phenotype. Both mutations impair MCT8 protein stability and interfere with proper subcellular trafficking. In one of the patients calcifications were observed in the basal ganglia at the age of 29 years; an abnormal neuroradiological feature at this age that has been linked to untreated (congenital) hypothyroidism and neural cretinism. Our studies extend on previous work by identifying two novel pathogenic mutations in SLC16A2 gene resulting in a mild clinical phenotype.
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Affiliation(s)
- Silvia Masnada
- Pediatric Neurology Unit, V. Buzzi Children's Hospital, Via Castelvetro 32, 20154, Milan, Italy
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
| | - Stefan Groenweg
- Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus MC, University Medical Center, CN, Rotterdam, The Netherlands
| | - Veronica Saletti
- Child Neurology Department, IRCCS Foundation C. Besta Neurological Institute, Milan, Italy
| | - Luisa Chiapparini
- Neuroradiology Unit, IRCCS Foundation C. Besta Neurological Institute, Milan, Italy
| | - Barbara Castellotti
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, IRCCS Foundation C. Besta Neurological Institute, Milan, Italy
| | - Ettore Salsano
- Unit of Neurodegenerative and Neurometabolic Rare Diseases, IRCCS Foundation C. Besta Neurological Institute, Milan, Italy
| | - W Edward Visser
- Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus MC, University Medical Center, CN, Rotterdam, The Netherlands
| | - Davide Tonduti
- Pediatric Neurology Unit, V. Buzzi Children's Hospital, Via Castelvetro 32, 20154, Milan, Italy.
- Child Neurology Department, IRCCS Foundation C. Besta Neurological Institute, Milan, Italy.
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Groeneweg S, Kersseboom S, van den Berge A, Dolcetta-Capuzzo A, van Geest FS, van Heerebeek REA, Arjona FJ, Meima ME, Peeters RP, Visser WE, Visser TJ. In Vitro Characterization of Human, Mouse, and Zebrafish MCT8 Orthologues. Thyroid 2019; 29:1499-1510. [PMID: 31436139 DOI: 10.1089/thy.2019.0009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Background: Mutations in the thyroid hormone (TH) transporter monocarboxylate transporter 8 (MCT8) cause MCT8 deficiency, characterized by severe intellectual and motor disability and abnormal serum thyroid function tests. Various Mct8 knock-out mouse models as well as mct8 knock-out and knockdown zebrafish models are used as a disease model for MCT8 deficiency. Although important for model eligibility, little is known about the functional characteristics of the MCT8 orthologues in these species. Therefore, we here compared the functional characteristics of mouse (mm) MCT8 and zebrafish (dr) Mct8 to human (hs) MCT8. Methods: We performed extensive transport studies in COS-1 and JEG-3 cells transiently transfected with hsMCT8, drMct8, and mmMCT8. Protein expression levels and subcellular localization were assessed by immunoblotting, surface biotinylation, and immunocytochemistry. Sequence alignment and structural modeling were used to interpret functional differences between the orthologues. Results: hsMCT8, drMct8, and mmMCT8 all facilitated the uptake and efflux of 3,3'-diiodothyronine (3,3'-T2), rT3, triiodothyronine (T3), and thyroxine (T4), although the initial uptake rates of drMct8 were 1.5-4.0-fold higher than for hsMCT8 and mmMCT8. drMct8 exhibited 3-50-fold lower apparent IC50 values than hsMCT8 and mmMCT8 for all tested substrates, and substrate preference of drMct8 (3,3'-T2, T3 > T4 > rT3) differed from hsMCT8 and mmMCT8 (T3 > T4 > rT3, 3,3'-T2). Compared with hsMCT8 and mmMCT8, cis-inhibition studies showed that T3 uptake by drMct8 was inhibited at a lower concentration and by a broader spectrum of TH metabolites. Total and cell surface expression levels of drMct8 and hsMCT8 were equal and both significantly exceeded those of mmMCT8. Structural modeling located most non-conserved residues outside the substrate pore, except for H192 in hsMCT8, which is replaced by a glutamine in drMct8. However, a H192Q substituent of hsMCT8 did not alter its transporter characteristics. Conclusion: Our studies substantiate the eligibility of mice and zebrafish models for human MCT8 deficiency. However, differences in the intrinsic transporter properties of MCT8 orthologues may exist, which should be realized when comparing MCT8 deficiency in different in vivo models. Moreover, our findings may indicate that the protein domains outside the substrate channel may play a role in substrate selection and protein stability.
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Affiliation(s)
- Stefan Groeneweg
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
| | - Simone Kersseboom
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
| | - Amanda van den Berge
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
| | - Anna Dolcetta-Capuzzo
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
- Department of Endocrinology and Internal Medicine, San Raffaele Scientific Institute, Milan, Italy
| | - Ferdy S van Geest
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
| | - Ramona E A van Heerebeek
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
| | - Francisco J Arjona
- Department of Animal Ecology and Physiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University Nijmegen, Nijmegen, The Netherlands
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marcel E Meima
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
| | - Robin P Peeters
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
| | - W Edward Visser
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
| | - Theo J Visser
- Department of Internal Medicine, Erasmus Medical Center, Academic Center for Thyroid Diseases, Rotterdam, The Netherlands
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Antioxidant, Anti-Inflammatory, and Multidrug Resistance Modulation Activity of Silychristin Derivatives. Antioxidants (Basel) 2019; 8:antiox8080303. [PMID: 31416138 PMCID: PMC6720199 DOI: 10.3390/antiox8080303] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/08/2019] [Accepted: 08/12/2019] [Indexed: 12/11/2022] Open
Abstract
Silychristin A is the second most abundant compound of silymarin. Silymarin complex was previously described as an antioxidant with multidrug resistance modulation activity. Here, the results of a classical biochemical antioxidant assay (ORAC) were compared with a cellular assay evaluating the antioxidant capacity of pure silychristin A and its derivatives (anhydrosilychristin, isosilychristin and 2,3-dehydrosilychristin A). All the tested compounds acted as antioxidants within the cells, but 2,3-dehydro- and anhydro derivatives were almost twice as potent as the other tested compounds. Similar results were obtained in LPS-stimulated macrophages, where 2,3-dehydro- and anhydrosilychristin inhibited NO production nearly twice as efficiently as silychristin A. The inhibition of P-glycoprotein (P-gp) was determined in vitro, and the respective sensitization of doxorubicin-resistant ovarian carcinoma overproducing P-gp was detected. Despite the fact that the inhibition of P-gp was demonstrated in a concentration-dependent manner for each tested compound, the sensitization of the resistant cell line was observed predominantly for silychristin A and 2,3-dehydrosilychristin A. However, anhydrosilychristin and isosilychristin affected the expression of both the P-gp (ABCB1) and ABCG2 genes. This is the first report showing that silychristin A and its 2,3-dehydro-derivative modulate multidrug resistance by the direct inhibition of P-gp, in contrast to anhydrosilychristin and isosilychristin modulating multidrug resistance by downregulating the expression of the dominant transmembrane efflux pumps.
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Woodruff TK. Tweets and Transformative Technologies: Enabling Our Endocrine Future. Endocrinology 2018; 159:1417-1418. [PMID: 29617756 DOI: 10.1210/en.2018-00114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/27/2018] [Indexed: 11/19/2022]
Affiliation(s)
- Teresa K Woodruff
- Department of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois
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