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Chincarini G, Walker DW, Wong F, Richardson SJ, Cumberland A, Tolcos M. Thyroid hormone analogues: Promising therapeutic avenues to improve the neurodevelopmental outcomes of intrauterine growth restriction. J Neurochem 2024. [PMID: 38742992 DOI: 10.1111/jnc.16124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 04/14/2024] [Accepted: 04/19/2024] [Indexed: 05/16/2024]
Abstract
Intrauterine growth restriction (IUGR) is a pregnancy complication impairing fetal growth and development. The compromised development is often attributed to disruptions of oxygen and nutrient supply from the placenta, resulting in a number of unfavourable physiological outcomes with impaired brain and organ growth. IUGR is associated with compromised development of both grey and white matter, predisposing the infant to adverse neurodevelopmental outcomes, including long-lasting cognitive and motor difficulties. Cerebral thyroid hormone (TH) signalling, which plays a crucial role in regulating white and grey matter development, is dysregulated in IUGR, potentially contributing to the neurodevelopmental delays associated with this condition. Notably, one of the major TH transporters, monocarboxylate transporter-8 (MCT8), is deficient in the fetal IUGR brain. Currently, no effective treatment to prevent or reverse IUGR exists. Management strategies involve close antenatal monitoring, management of maternal risk factors if present and early delivery if IUGR is found to be severe or worsening in utero. The overall goal is to determine the most appropriate time for delivery, balancing the risks of preterm birth with further fetal compromise due to IUGR. Drug candidates have shown either adverse effects or little to no benefits in this vulnerable population, urging further preclinical and clinical investigation to establish effective therapies. In this review, we discuss the major neuropathology of IUGR driven by uteroplacental insufficiency and the concomitant long-term neurobehavioural impairments in individuals born IUGR. Importantly, we review the existing clinical and preclinical literature on cerebral TH signalling deficits, particularly the impaired expression of MCT8 and their correlation with IUGR. Lastly, we discuss the current evidence on MCT8-independent TH analogues which mimic the brain actions of THs by being metabolised in a similar manner as promising, albeit underappreciated approaches to promote grey and white matter development and improve the neurobehavioural outcomes following IUGR.
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Affiliation(s)
- Ginevra Chincarini
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia
| | - David W Walker
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia
- Monash Newborn Health, Monash Medical Centre, Clayton, Melbourne, Victoria, Australia
| | - Flora Wong
- Monash Newborn Health, Monash Medical Centre, Clayton, Melbourne, Victoria, Australia
| | | | - Angela Cumberland
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia
| | - Mary Tolcos
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia
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Emamnejad R, Dass M, Mahlis M, Bozkurt S, Ye S, Pagnin M, Theotokis P, Grigoriadis N, Petratos S. Thyroid hormone-dependent oligodendroglial cell lineage genomic and non-genomic signaling through integrin receptors. Front Pharmacol 2022; 13:934971. [PMID: 36133808 PMCID: PMC9483185 DOI: 10.3389/fphar.2022.934971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Multiple sclerosis (MS) is a heterogeneous autoimmune disease whereby the pathological sequelae evolve from oligodendrocytes (OLs) within the central nervous system and are targeted by the immune system, which causes widespread white matter pathology and results in neuronal dysfunction and neurological impairment. The progression of this disease is facilitated by a failure in remyelination following chronic demyelination. One mediator of remyelination is thyroid hormone (TH), whose reliance on monocarboxylate transporter 8 (MCT8) was recently defined. MCT8 facilitates the entry of THs into oligodendrocyte progenitor cell (OPC) and pre-myelinating oligodendrocytes (pre-OLs). Patients with MS may exhibit downregulated MCT8 near inflammatory lesions, which emphasizes an inhibition of TH signaling and subsequent downstream targeted pathways such as phosphoinositide 3-kinase (PI3K)-Akt. However, the role of the closely related mammalian target of rapamycin (mTOR) in pre-OLs during neuroinflammation may also be central to the remyelination process and is governed by various growth promoting signals. Recent research indicates that this may be reliant on TH-dependent signaling through β1-integrins. This review identifies genomic and non-genomic signaling that is regulated through mTOR in TH-responsive pre-OLs and mature OLs in mouse models of MS. This review critiques data that implicates non-genomic Akt and mTOR signaling in response to TH-dependent integrin receptor activation in pre-OLs. We have also examined whether this can drive remyelination in the context of neuroinflammation and associated sequelae. Importantly, we outline how novel therapeutic small molecules are being designed to target integrin receptors on oligodendroglial lineage cells and whether these are viable therapeutic options for future use in clinical trials for MS.
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Affiliation(s)
- Rahimeh Emamnejad
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, VIC, Australia
| | - Mary Dass
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, VIC, Australia
| | - Michael Mahlis
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, VIC, Australia
| | - Salome Bozkurt
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, VIC, Australia
| | - Sining Ye
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, VIC, Australia
| | - Maurice Pagnin
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, VIC, Australia
| | - Paschalis Theotokis
- B’, Department of Neurology, Laboratory of Experimental Neurology and Neuroimmunology, AHEPA University Hospital, Thessaloniki, Greece
| | - Nikolaos Grigoriadis
- B’, Department of Neurology, Laboratory of Experimental Neurology and Neuroimmunology, AHEPA University Hospital, Thessaloniki, Greece
| | - Steven Petratos
- Department of Neuroscience, Central Clinical School, Monash University, Prahran, VIC, Australia
- *Correspondence: Steven Petratos,
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Zhang Q, Yang Q, Zhou X, Qin Z, Yi S, Luo J. Characteristics of Allan-Herndon-Dudley Syndrome in Chinese children: Identification of two novel pathogenic variants of the SLC16A2 gene. Front Pediatr 2022; 10:1050023. [PMID: 36458135 PMCID: PMC9705582 DOI: 10.3389/fped.2022.1050023] [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: 09/21/2022] [Accepted: 11/02/2022] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE The aim of this study was to identify causative variants associated with Allan-Herndon-Dudley syndrome (AHDS) in two unrelated Chinese families, and to determine their potential pathogenicity. We also summarized the core clinical symptoms of AHDS by reviewing the related literature. METHODS Genomic DNA was isolated from the peripheral blood of AHDS patients and their family members. Whole exome sequencing (WES) was performed on the proband from each family to identify the candidate variants. Subsequently, Sanger sequencing was used to verify the identified candidate variants and to assess co-segregation among the available family members. In silico prediction combined with 3D protein modeling was conducted to predict the functional effects of the variants on the encoded protein. RESULTS Two novel hemizygous variants of SLC16A2, c.1111_1112insGTCTTGT (Gly375fs*6) and c.942delA (Val315fs*28), were detected in two patients. We compared the clinical symptoms of the patients with all patients with AHDS reported in China and those reported in the literature. While both our patients presented symptoms mostly consistent with AHDS, Patient 1 had no abnormal brain structure and thyroid function, and yet showed other symptoms including lactic aciduria, conjunctival hyperemia, vomiting, laryngeal stridor, low immunoglobulin and iron levels. CONCLUSIONS This study expands the mutation spectrum of AHDS and has clinical value for variant-based prenatal and postnatal screening for this condition. Doctors often have difficulty identifying AHDS by using clinical symptoms. WES can help to identify specific disorder when diagnosis cannot be made based on symptoms alone.
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Affiliation(s)
- Qiang Zhang
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Qi Yang
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Xunzhao Zhou
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Zailong Qin
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Shang Yi
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
| | - Jingsi Luo
- The Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region, Guangxi Birth Defects Prevention and Control Institute, Nanning, China
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5
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Gowda VK, Gupta P, Shivappa SK, Benakappa N. Thyroid Hormone Transporter Defect: Allan Herndon Dudley Syndrome, Masquerading as Dyskinetic Cerebral Palsy. J Pediatr Neurosci 2021; 16:293-295. [PMID: 36531774 PMCID: PMC9757515 DOI: 10.4103/jpn.jpn_135_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 10/22/2020] [Accepted: 11/22/2020] [Indexed: 06/17/2023] Open
Abstract
Allan Herndon Dudley syndrome (AHDS) is a rare X-linked recessive disorder due to mutation in the SLC16A2 gene, which encodes a thyroid hormone (TH) transporter that facilitates the movement of TH across the neurons. Mutation in this gene leads to a lack of T3 and T4 entry in the brain, which causes central hypothyroidism and dysthyroidism in the peripheral tissue. We report a child, a 21-month-old boy, who presented with developmental delay and stiffness. The child had facial dysmorphism with dystonia. MRI of the brain was normal. Thyroid profile showed low free T4, and normal TSH but high free T3. Hence, AHDS was suspected and was confirmed by targeted next-generation testing and Sanger sequencing.
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Affiliation(s)
| | - Priya Gupta
- Department of Pediatric Neurology, Indira Gandhi Institute of Child Health, Bangalore, India
| | - Sanjay K Shivappa
- Department of Pediatric Medicine, Indira Gandhi Institute of Child Health, Bangalore, India
| | - Naveen Benakappa
- Department of Pediatric Medicine, Indira Gandhi Institute of Child Health, Bangalore, India
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6
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Pagnin M, Kondos-Devcic D, Chincarini G, Cumberland A, Richardson SJ, Tolcos M. Role of thyroid hormones in normal and abnormal central nervous system myelination in humans and rodents. Front Neuroendocrinol 2021; 61:100901. [PMID: 33493504 DOI: 10.1016/j.yfrne.2021.100901] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/07/2021] [Accepted: 01/16/2021] [Indexed: 12/13/2022]
Abstract
Thyroid hormones (THs) are instrumental in promoting the molecular mechanisms which underlie the complex nature of neural development and function within the central nervous system (CNS) in vertebrates. The key neurodevelopmental process of myelination is conserved between humans and rodents, of which both experience peak fetal TH concentrations concomitant with onset of myelination. The importance of supplying adequate levels of THs to the myelin producing cells, the oligodendrocytes, for promoting their maturation is crucial for proper neural function. In this review we examine the key TH distributor and transport proteins, including transthyretin (TTR) and monocarboxylate transporter 8 (MCT8), essential for supporting proper oligodendrocyte and myelin health; and discuss disorders with impaired TH signalling in relation to abnormal CNS myelination in humans and rodents. Furthermore, we explore the importance of using novel TH analogues in the treatment of myelination disorders associated with abnormal TH signalling.
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Affiliation(s)
- Maurice Pagnin
- School of Health and Biomedical Sciences, RMIT University, Bundoora 3083, Australia
| | - Delphi Kondos-Devcic
- School of Health and Biomedical Sciences, RMIT University, Bundoora 3083, Australia
| | - Ginevra Chincarini
- School of Health and Biomedical Sciences, RMIT University, Bundoora 3083, Australia
| | - Angela Cumberland
- School of Health and Biomedical Sciences, RMIT University, Bundoora 3083, Australia
| | | | - Mary Tolcos
- School of Health and Biomedical Sciences, RMIT University, Bundoora 3083, Australia.
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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: 86] [Impact Index Per Article: 21.5] [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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Vancamp P, Demeneix BA, Remaud S. Monocarboxylate Transporter 8 Deficiency: Delayed or Permanent Hypomyelination? Front Endocrinol (Lausanne) 2020; 11:283. [PMID: 32477268 PMCID: PMC7237703 DOI: 10.3389/fendo.2020.00283] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/15/2020] [Indexed: 12/11/2022] Open
Abstract
Monocarboxylate transporter 8 (MCT8) deficiency or the Allan-Herndon-Dudley Syndrome (AHDS) is an X-linked psychomotor disability syndrome with around 320 clinical cases described worldwide. SLC16A2 gene mutations, encoding the thyroid hormone (TH) transporter MCT8, result in intellectual disability due to impaired TH uptake in the developing brain. MCT8 deficiency is a multi-organ affecting disease with a predominant neuronal cell-based pathology, with the glial component inadequately investigated. However, deficiency in myelin, a key component of white matter (WM) enabling fast nerve conduction, is a TH-dependent hallmark of the disease. Nevertheless, analysis of the myelin status in AHDS patients has led to conflicting interpretations. The majority of individual case studies reported delayed myelination, that was restored later in life. In contrast, post-mortem studies and high-resolution MRIs detected WM (micro-) abnormalities throughout adolescence, suggesting permanent hypomyelination. Thus, interpretations vary depending on methodology to investigate WM microstructure. Further, it is unknown whether the mutation within the MCT8 is linked to the severity of the myelin deficiency. Consequently, terminology is inconsistent among reports, and AHDS is occasionally misdiagnosed as another WM disorder. The evolutionary conserved TH signaling pathway that promotes the generation of myelinating oligodendrocytes enabled deciphering how the lack of MCT8 might affect myelinogenesis. Linking patient findings on myelination to those obtained from models of MCT8 deficiency revealed underlying pathophysiological mechanisms, but knowledge gaps remain, notably how myelination progresses both spatially and temporally in MCT8 deficiency. This limits predicting how myelin integrity might benefit therapeutically, and when to initiate. A recurrent observation in clinical trials is the absence of neurological improvement. Testing MCT8-independent thyromimetics in models, and evaluating treatments used in other demyelinating diseases, despite different etiologies, is crucial to propose new therapeutic strategies combatting this devastating disease.
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Affiliation(s)
- Pieter Vancamp
- UMR 7221 Molecular Physiology and Adaptation, Centre National de le Recherche Scientifique-Muséum National d'Histoire Naturelle, Paris, France
| | - Barbara A Demeneix
- UMR 7221 Molecular Physiology and Adaptation, Centre National de le Recherche Scientifique-Muséum National d'Histoire Naturelle, Paris, France
| | - Sylvie Remaud
- UMR 7221 Molecular Physiology and Adaptation, Centre National de le Recherche Scientifique-Muséum National d'Histoire Naturelle, Paris, France
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9
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Remerand G, Boespflug-Tanguy O, Tonduti D, Touraine R, Rodriguez D, Curie A, Perreton N, Des Portes V, Sarret C. Expanding the phenotypic spectrum of Allan-Herndon-Dudley syndrome in patients with SLC16A2 mutations. Dev Med Child Neurol 2019; 61:1439-1447. [PMID: 31410843 DOI: 10.1111/dmcn.14332] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/07/2019] [Indexed: 01/01/2023]
Abstract
The aim of the study was to redefine the phenotype of Allan-Herndon-Dudley syndrome (AHDS), which is caused by mutations in the SLC16A2 gene that encodes the brain transporter of thyroid hormones. Clinical phenotypes, brain imaging, thyroid hormone profiles, and genetic data were compared to the existing literature. Twenty-four males aged 11 months to 29 years had a mutation in SLC16A2, including 12 novel mutations and five previously described mutations. Sixteen patients presented with profound developmental delay, three had severe intellectual disability with poor language and walking with an aid, four had moderate intellectual disability with language and walking abilities, and one had mild intellectual disability with hypotonia. Overall, eight had learned to walk, all had hypotonia, 17 had spasticity, 18 had dystonia, 12 had choreoathetosis, 19 had hypomyelination, and 10 had brain atrophy. Kyphoscoliosis (n=12), seizures (n=7), and pneumopathies (n=5) were the most severe complications. This study extends the phenotypic spectrum of AHDS to a mild intellectual disability with hypotonia. Developmental delay, hypotonia, hypomyelination, and thyroid hormone profile help to diagnose patients. Clinical course depends on initial severity, with stable acquisition after infancy; this may be adversely affected by neuro-orthopaedic, pulmonary, and epileptic complications. WHAT THIS PAPER ADDS: Mild intellectual disability is associated with SLC16A2 mutations. A thyroid hormone profile with a free T3 /T4 ratio higher than 0.75 can help diagnose patients. Patients with SLC16A2 mutations present a broad spectrum of neurological phenotypes that are also observed in other hypomyelinating disorders. Axial hypotonia is a consistent feature of Allan-Herndon-Dudley syndrome and leads to specific complications.
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Affiliation(s)
- Ganaelle Remerand
- Centre de Compétence des Leucodystrophies et Leucoencéphalopathies de Cause Rare, Pôle Femme et Enfant, Hôpital Estaing, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France
| | - Odile Boespflug-Tanguy
- Centre de Référence des Leucodystrophies et Leucoencéphalopathies de Cause Rare, Service de Neurologie Pédiatrique, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, Paris, France.,NeuroDiderot, INSERM UMR1141, Université Paris Diderot, Paris, France
| | - Davide Tonduti
- Unit of Child Neurology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.,Unit of Child Neurology, V. Buzzi Children's Hospital, Milan, Italy
| | - Renaud Touraine
- Service de Génétique, Centre Hospitalier Universitaire de Saint-Etienne, Saint-Etienne, France
| | - Diana Rodriguez
- Sorbonne Université, GRC no. 19, Pathologies Congénitales du Cervelet-LeucoDystrophies, Assistance Publique-Hôpitaux de Paris, Hôpital Armand Trousseau, Paris, France.,Centre de Référence Neurogénétique, Service de Neurologie Pédiatrique, Assistance Publique-Hôpitaux de Paris, Hôpital Armand Trousseau, Paris, France
| | - Aurore Curie
- Centre de Référence des Déficiences Intellectuelles de Cause Rare, Service de Neurologie Pédiatrique, Centre Hospitalier Universitaire de Lyon, Hôpital Femme-Mère-Enfant, Lyon, France
| | - Nathalie Perreton
- CIC 1407Inserm, Centre Hospitalo-Universitaire de Lyon, Lyon, France
| | - Vincent Des Portes
- Centre de Référence des Déficiences Intellectuelles de Cause Rare, Service de Neurologie Pédiatrique, Centre Hospitalier Universitaire de Lyon, Hôpital Femme-Mère-Enfant, Lyon, France
| | - Catherine Sarret
- Centre de Compétence des Leucodystrophies et Leucoencéphalopathies de Cause Rare, Pôle Femme et Enfant, Hôpital Estaing, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France.,IGCNC, Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut Pascal, Clermont-Ferrand, France
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Braun D, Reuter U, Schweizer U. Modeling the Biochemical Phenotype of MCT8 Mutations In Vitro: Resolving a Troubling Inconsistency. Endocrinology 2019; 160:1536-1546. [PMID: 31127274 DOI: 10.1210/en.2019-00069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 04/19/2019] [Indexed: 02/07/2023]
Abstract
Allan-Herndon-Dudley syndrome (AHDS) is a severe genetic disease caused by mutations in the monocarboxylate transporter 8 (MCT8) gene. MCT8 mediates transport of thyroid hormones in and out of cells, which is thought to play a pivotal role for embryonic and postnatal development of the human brain. Disconcertingly, MCT8R271H leads to a severe form of AHDS but shows residual transport activity when expressed in several types of cultured cells. Here we try to determine the mechanism behind the transport function of MCT8R271H found in overexpressing cell systems. Mutations of Arg271 were introduced into human MCT8 and stably transfected into Madin-Darby canine kidney cells and the human-derived cell line JEG1. Radioactive thyroid hormone-uptake experiments were performed to analyze the pH-dependent effect of the mutation on transport activity. Arg271His transports thyroid hormones in and out of cells in a pH-dependent manner. Its transport activity increases below pH 7.3 and is clearly diminished at physiological pH. The Michaelis constant of the mutant is unaltered, whereas the maximum velocity is reduced. The expression of Arg271His in JEG1 cells leads to an almost nonfunctional transporter at physiological pH replicating the human phenotype for this mutant in vitro and demonstrates, again, that mutant MCT8 activity depends on cellular background. The protonation of His271 at acidic pH restores activity of the mutant protein, which is not active in its deprotonated form at physiological pH. Thus, experimental parameters must be controlled carefully when modeling MCT8 deficiency in cells.
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Affiliation(s)
- Doreen Braun
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Uschi Reuter
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Ulrich Schweizer
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
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Oligodendroglial Lineage Cells in Thyroid Hormone-Deprived Conditions. Stem Cells Int 2019; 2019:5496891. [PMID: 31182964 PMCID: PMC6515029 DOI: 10.1155/2019/5496891] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 03/20/2019] [Indexed: 01/06/2023] Open
Abstract
Oligodendrocytes are supporting glial cells that ensure the metabolism and homeostasis of neurons with specific synaptic axoglial interactions in the central nervous system. These require key myelinating glial trophic signals important for growth and metabolism. Thyroid hormone (TH) is one such trophic signal that regulates oligodendrocyte maturation, myelination, and oligodendroglial synaptic dynamics via either genomic or nongenomic pathways. The intracellular and extracellular transport of TH is facilitated by a specific transmembrane transporter known as the monocarboxylate transporter 8 (MCT8). Dysfunction of the MCT8 due to mutation, inhibition, or downregulation during brain development leads to inherited hypomyelination, which manifests as psychomotor retardation in the X-linked inherited Allan-Herndon-Dudley syndrome (AHDS). In particular, oligodendroglial-specific MCT8 deficiency may restrict the intracellular T3 availability, culminating in deficient metabolic communication between the oligodendrocytes and the neurons they ensheath, potentially promulgating neurodegenerative adult diseases such as multiple sclerosis (MS). Based on the therapeutic effects exhibited by TH in various preclinical studies, particularly related to its remyelinating potential, TH has now entered the initial stages of a clinical trial to test the therapeutic efficacy in relapsing-remitting MS patients (NCT02506751). However, TH analogs, such as DITPA or Triac, may well serve as future therapeutic options to rescue mature oligodendrocytes and/or promote oligodendrocyte precursor cell differentiation in an environment of MCT8 deficiency within the CNS. This review outlines the therapeutic strategies to overcome the differentiation blockade of oligodendrocyte precursors and maintain mature axoglial interactions in TH-deprived conditions.
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Hartley MD, Banerji T, Tagge IJ, Kirkemo LL, Chaudhary P, Calkins E, Galipeau D, Shokat MD, DeBell MJ, Van Leuven S, Miller H, Marracci G, Pocius E, Banerji T, Ferrara SJ, Meinig JM, Emery B, Bourdette D, Scanlan TS. Myelin repair stimulated by CNS-selective thyroid hormone action. JCI Insight 2019; 4:126329. [PMID: 30996143 PMCID: PMC6538346 DOI: 10.1172/jci.insight.126329] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 03/12/2019] [Indexed: 12/21/2022] Open
Abstract
Oligodendrocyte processes wrap axons to form neuroprotective myelin sheaths, and damage to myelin in disorders, such as multiple sclerosis (MS), leads to neurodegeneration and disability. There are currently no approved treatments for MS that stimulate myelin repair. During development, thyroid hormone (TH) promotes myelination through enhancing oligodendrocyte differentiation; however, TH itself is unsuitable as a remyelination therapy due to adverse systemic effects. This problem is overcome with selective TH agonists, sobetirome and a CNS-selective prodrug of sobetirome called Sob-AM2. We show here that TH and sobetirome stimulated remyelination in standard gliotoxin models of demyelination. We then utilized a genetic mouse model of demyelination and remyelination, in which we employed motor function tests, histology, and MRI to demonstrate that chronic treatment with sobetirome or Sob-AM2 leads to significant improvement in both clinical signs and remyelination. In contrast, chronic treatment with TH in this model inhibited the endogenous myelin repair and exacerbated disease. These results support the clinical investigation of selective CNS-penetrating TH agonists, but not TH, for myelin repair.
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Affiliation(s)
- Meredith D. Hartley
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
- VA Portland Health Care System, Portland, Oregon, USA
| | - Tania Banerji
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
| | | | - Lisa L. Kirkemo
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
- VA Portland Health Care System, Portland, Oregon, USA
| | - Priya Chaudhary
- VA Portland Health Care System, Portland, Oregon, USA
- Department of Neurology, and
| | - Evan Calkins
- VA Portland Health Care System, Portland, Oregon, USA
- Department of Neurology, and
| | - Danielle Galipeau
- VA Portland Health Care System, Portland, Oregon, USA
- Department of Neurology, and
| | - Mitra D. Shokat
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Margaret J. DeBell
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Shelby Van Leuven
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Hannah Miller
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Gail Marracci
- VA Portland Health Care System, Portland, Oregon, USA
- Department of Neurology, and
| | - Edvinas Pocius
- VA Portland Health Care System, Portland, Oregon, USA
- Department of Neurology, and
| | - Tapasree Banerji
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Skylar J. Ferrara
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - J. Matthew Meinig
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Ben Emery
- Department of Neurology, and
- Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, Oregon, USA
| | - Dennis Bourdette
- VA Portland Health Care System, Portland, Oregon, USA
- Department of Neurology, and
| | - Thomas S. Scanlan
- Department of Physiology & Pharmacology and Program in Chemical Biology, Oregon Health & Science University, Portland, Oregon, USA
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13
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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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14
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Abstract
Allan-Herndon-Dudley syndrome is a rare X-linked neurologic condition caused by mutations in monocarboxylate transporter 8 ( MCT8), which leads to deficient thyroid hormone transport. Typical features include severe cognitive impairment, truncal hypotonia, spastic paraplegia, weakness, and speech difficulties. Minimal literature exists describing the ocular findings in patients with Allan-Herndon-Dudley syndrome. We describe 4 male siblings affected with Allan-Herndon-Dudley syndrome with a novel nonsense mutation (Q90X) in the MCT8 protein. All affected siblings presented with classic findings of Allan-Herndon-Dudley syndrome, and each of the siblings also developed intermittent esotropia. This group of affected siblings represents the first consistent documentation of strabismus in Allan-Herndon-Dudley syndrome, suggesting a possible association between this clinical finding and the neurologic syndrome.
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Affiliation(s)
- Cole J Swiston
- 1 Gundersen Health System, Department of Ophthalmology, Lacrosse, WI, USA
| | - David L Nash
- 1 Gundersen Health System, Department of Ophthalmology, Lacrosse, WI, USA
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15
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Silva N, Louro B, Trindade M, Power DM, Campinho MA. Transcriptomics reveal an integrative role for maternal thyroid hormones during zebrafish embryogenesis. Sci Rep 2017; 7:16657. [PMID: 29192226 PMCID: PMC5709499 DOI: 10.1038/s41598-017-16951-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 11/20/2017] [Indexed: 02/06/2023] Open
Abstract
Thyroid hormones (THs) are essential for embryonic brain development but the genetic mechanisms involved in the action of maternal THs (MTHs) are still largely unknown. As the basis for understanding the underlying genetic mechanisms of MTHs regulation we used an established zebrafish monocarboxylic acid transporter 8 (MCT8) knock-down model and characterised the transcriptome in 25hpf zebrafish embryos. Subsequent mapping of differentially expressed genes using Reactome pathway analysis together with in situ expression analysis and immunohistochemistry revealed the genetic networks and cells under MTHs regulation during zebrafish embryogenesis. We found 4,343 differentially expressed genes and the Reactome pathway analysis revealed that TH is involved in 1681 of these pathways. MTHs regulated the expression of core developmental pathways, such as NOTCH and WNT in a cell specific context. The cellular distribution of neural MTH-target genes demonstrated their cell specific action on neural stem cells and differentiated neuron classes. Taken together our data show that MTHs have a role in zebrafish neurogenesis and suggest they may be involved in cross talk between key pathways in neural development. Given that the observed MCT8 zebrafish knockdown phenotype resembles the symptoms in human patients with Allan-Herndon-Dudley syndrome our data open a window into understanding the genetics of this human congenital condition.
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Affiliation(s)
- Nadia Silva
- Comparative Endocrinology and Integrative Biology Group, Centre for Marine Sciences (CCMAR), Universidade do Algarve, Faro, Portugal
| | - Bruno Louro
- Comparative Endocrinology and Integrative Biology Group, Centre for Marine Sciences (CCMAR), Universidade do Algarve, Faro, Portugal
| | - Marlene Trindade
- Comparative Endocrinology and Integrative Biology Group, Centre for Marine Sciences (CCMAR), Universidade do Algarve, Faro, Portugal
| | - Deborah M Power
- Comparative Endocrinology and Integrative Biology Group, Centre for Marine Sciences (CCMAR), Universidade do Algarve, Faro, Portugal
| | - Marco A Campinho
- Comparative Endocrinology and Integrative Biology Group, Centre for Marine Sciences (CCMAR), Universidade do Algarve, Faro, Portugal.
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16
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Lee JY, Kim MJ, Deliyanti D, Azari MF, Rossello F, Costin A, Ramm G, Stanley EG, Elefanty AG, Wilkinson-Berka JL, Petratos S. Overcoming Monocarboxylate Transporter 8 (MCT8)-Deficiency to Promote Human Oligodendrocyte Differentiation and Myelination. EBioMedicine 2017; 25:122-135. [PMID: 29111262 PMCID: PMC5704066 DOI: 10.1016/j.ebiom.2017.10.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 10/05/2017] [Accepted: 10/16/2017] [Indexed: 01/09/2023] Open
Abstract
Cell membrane thyroid hormone (TH) transport can be facilitated by the monocarboxylate transporter 8 (MCT8), encoded by the solute carrier family 16 member 2 (SLC16A2) gene. Human mutations of the gene, SLC16A2, result in the X-linked-inherited psychomotor retardation and hypomyelination disorder, Allan-Herndon-Dudley syndrome (AHDS). We posited that abrogating MCT8-dependent TH transport limits oligodendrogenesis and myelination. We show that human oligodendrocytes (OL), derived from the NKX2.1-GFP human embryonic stem cell (hESC) reporter line, express MCT8. Moreover, treatment of these cultures with DITPA (an MCT8-independent TH analog), up-regulates OL differentiation transcription factors and myelin gene expression. DITPA promotes hESC-derived OL myelination of retinal ganglion axons in co-culture. Pharmacological and genetic blockade of MCT8 induces significant OL apoptosis, impairing myelination. DITPA treatment limits OL apoptosis mediated by SLC16A2 down-regulation primarily signaling through AKT phosphorylation, driving myelination. Our results highlight the potential role of MCT8 in TH transport for human OL development and may implicate DITPA as a promising treatment for developmentally-regulated myelination in AHDS. NKX2.1-based sorting enhances OL derivation from hESC MCT8 is required for the survival of OL precursor cells DITPA promotes OL differentiation and myelination DITPA overrides SLC16A2 (MCT8) down-regulation to potentiate myelination
Thyroid hormone is vital for oligodendrocyte differentiation and myelination. Lee and colleagues show that MCT8 is an integral thyroid hormone transporter for oligodendrocytes derived from human embryonic stem cells. Knockdown of this transporter induces apoptosis of OLs, which could be prevented by the provision of DITPA.
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Affiliation(s)
- Jae Young Lee
- Department of Medicine, Central Clinical School, Monash University, Prahran, Victoria 3004, Australia
| | - Min Joung Kim
- Department of Medicine, Central Clinical School, Monash University, Prahran, Victoria 3004, Australia
| | - Devy Deliyanti
- Department of Diabetes, Central Clinical School, Monash University, Prahran, Victoria 3004, Australia
| | - Michael F Azari
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria 3083, Australia
| | - Fernando Rossello
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Adam Costin
- The Clive & Vera Ramaciotti Centre for Cryo Electron Microscopy, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Georg Ramm
- The Clive & Vera Ramaciotti Centre for Cryo Electron Microscopy, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Edouard G Stanley
- Murdoch Children's Research Institute, The Royal Children's Hospital, Flemington Rd, Parkville, Victoria 3052, Australia
| | - Andrew G Elefanty
- Murdoch Children's Research Institute, The Royal Children's Hospital, Flemington Rd, Parkville, Victoria 3052, Australia; Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, Victoria 3052, Australia
| | | | - Steven Petratos
- Department of Medicine, Central Clinical School, Monash University, Prahran, Victoria 3004, Australia.
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17
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Groeneweg S, Lima de Souza EC, Meima ME, Peeters RP, Visser WE, Visser TJ. Outward-Open Model of Thyroid Hormone Transporter Monocarboxylate Transporter 8 Provides Novel Structural and Functional Insights. Endocrinology 2017; 158:3292-3306. [PMID: 28977587 DOI: 10.1210/en.2017-00082] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 07/06/2017] [Indexed: 12/28/2022]
Abstract
Monocarboxylate transporter 8 (MCT8) facilitates cellular uptake and efflux of thyroid hormone (TH). Mutations in MCT8 result in severe intellectual and motor disability known as the Allan-Herndon-Dudley syndrome (AHDS). Previous studies have provided valuable insights into the putative mechanism of substrate binding in the inward-open conformation, required for TH efflux. The current study aims to delineate the mechanism of substrate binding in the outward-open conformation, required for TH uptake. Extensive chemical modification and site-directed mutagenesis studies were used to guide protein homology modeling of MCT8 in the outward-open conformation. Arg271 and Arg445 were modified by phenylglyoxal, which was partially prevented in the presence of substrate. Substrate docking in our outward-open model suggested an important role for His192 and Arg445 in substrate binding. Interestingly, mutations affecting these residues have been identified in patients who have AHDS. In addition, our outward-open model predicted the location of Phe189, Met227, Phe279, Gly282, Phe287, and Phe501 at the substrate-binding center, and their Ala substitution differentially affected the apparent Vmax and Km of T3 transport, with F189A, F279A, and F287A showing the highest impact. Thus, here we present an MCT8 homology model in the outward-open conformation, which supports the important role of His192 and Arg445 in substrate docking and identifies critical residues at the putative substrate-binding center. Our findings provide insights into MCT8 structure and function, which add to our understanding of the pathogenic mechanism of mutations found in patients who have AHDS and can be used to screen for novel substrates and inhibitors.
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Affiliation(s)
- Stefan Groeneweg
- The Rotterdam Thyroid Center & Department of Internal Medicine, Erasmus Medical Center, 3015 CN, Rotterdam, The Netherlands
| | - Elaine C Lima de Souza
- The Rotterdam Thyroid Center & Department of Internal Medicine, Erasmus Medical Center, 3015 CN, Rotterdam, The Netherlands
| | - Marcel E Meima
- The Rotterdam Thyroid Center & Department of Internal Medicine, Erasmus Medical Center, 3015 CN, Rotterdam, The Netherlands
| | - Robin P Peeters
- The Rotterdam Thyroid Center & Department of Internal Medicine, Erasmus Medical Center, 3015 CN, Rotterdam, The Netherlands
| | - W Edward Visser
- The Rotterdam Thyroid Center & Department of Internal Medicine, Erasmus Medical Center, 3015 CN, Rotterdam, The Netherlands
| | - Theo J Visser
- The Rotterdam Thyroid Center & Department of Internal Medicine, Erasmus Medical Center, 3015 CN, Rotterdam, The Netherlands
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18
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Novara F, Groeneweg S, Freri E, Estienne M, Reho P, Matricardi S, Castellotti B, Visser WE, Zuffardi O, Visser TJ. Clinical and Molecular Characteristics of SLC16A2 (MCT8) Mutations in Three Families with the Allan-Herndon-Dudley Syndrome. Hum Mutat 2017; 38:260-264. [PMID: 27805744 DOI: 10.1002/humu.23140] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 10/18/2016] [Accepted: 10/21/2016] [Indexed: 11/11/2022]
Abstract
Mutations in the thyroid hormone transporter SLC16A2 (MCT8) cause the Allan-Herndon-Dudley Syndrome (AHDS), characterized by severe psychomotor retardation and peripheral thyrotoxicosis. Here, we report three newly identified AHDS patients. Previously documented mutations were identified in probands 1 (p.R271H) and 2 (p.G564R), resulting in a severe clinical phenotype. A novel mutation (p.G564E) was identified in proband 3, affecting the same Gly564 residue, but resulting in a relatively mild clinical phenotype. Functional analysis in transiently transfected COS-1 and JEG-3 cells showed a near-complete inactivation of TH transport for p.G564R, whereas considerable cell-type-dependent residual transport activity was observed for p.G564E. Both mutants showed a strong decrease in protein expression levels, but differentially affected Vmax and Km values of T3 transport. Our findings illustrate that different mutations affecting the same residue may have a differential impact on SLC16A2 transporter function, which translates into differences in severity of the clinical phenotype.
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Affiliation(s)
- Francesca Novara
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Stefan Groeneweg
- Department of Internal Medicine and Rotterdam Thyroid Center, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Elena Freri
- Department of Pediatric Neuroscience, Foundation I.R.C.C.S. Neurological Institute "C. Besta", Milan, Italy
| | - Margherita Estienne
- Department of Pediatric Neuroscience, Foundation I.R.C.C.S. Neurological Institute "C. Besta", Milan, Italy
| | - Paolo Reho
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Sara Matricardi
- Department of Pediatric Neuroscience, Foundation I.R.C.C.S. Neurological Institute "C. Besta", Milan, Italy.,Department of Pediatrics, University of Chieti, Chieti, Italy
| | - Barbara Castellotti
- SOSD Genetica delle Malattie Neurodegenerative e Metaboliche, U.O Patologia Clinica, Foundation I.R.C.C.S. Neurological Institute "C. Besta", Milan, Italy
| | - W Edward Visser
- Department of Internal Medicine and Rotterdam Thyroid Center, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Orsetta Zuffardi
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Theo J Visser
- Department of Internal Medicine and Rotterdam Thyroid Center, Erasmus University Medical Center, Rotterdam, The Netherlands
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19
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Lee JY, Petratos S. Thyroid Hormone Signaling in Oligodendrocytes: from Extracellular Transport to Intracellular Signal. Mol Neurobiol 2016; 53:6568-6583. [PMID: 27427390 DOI: 10.1007/s12035-016-0013-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 07/10/2016] [Indexed: 01/24/2023]
Abstract
Thyroid hormone plays an important role in central nervous system (CNS) development, including the myelination of variable axonal calibers. It is well-established that thyroid hormone is required for the terminal differentiation of oligodendrocyte precursor cells (OPCs) into myelinating oligodendrocytes by inducing rapid cell-cycle arrest and constant transcription of pro-differentiation genes. This is well supported by the hypomyelinating phenotypes exhibited by patients with congenital hypothyroidism, cretinism. During development, myelinating oligodendrocytes only appear after the formation of neural circuits, indicating that the timing of oligodendrocyte differentiation is important. Since fetal and post-natal serum thyroid hormone levels peak at the stage of active myelination, it is suspected that the timing of oligodendrocyte development is finely controlled by thyroid hormone. The essential machinery for thyroid hormone signaling such as deiodinase activity (utilized by cells to auto-regulate the level of thyroid hormone), and nuclear thyroid hormone receptors (for gene transcription) are expressed on oligodendrocytes. In this review, we discuss the known and potential thyroid hormone signaling pathways that may regulate oligodendrocyte development and CNS myelination. Moreover, we evaluate the potential of targeting thyroid hormone signaling for white matter injury or disease.
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Affiliation(s)
- Jae Young Lee
- Department of Medicine, Central Clinical School, Monash University, Prahran, Victoria, 3004, Australia.,ToolGen, Inc., #1204, Byucksan Digital Valley 6-cha, Seoul, South Korea
| | - Steven Petratos
- Department of Medicine, Central Clinical School, Monash University, Prahran, Victoria, 3004, Australia.
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