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Fang Y, Wan JP, Zhang RJ, Sun F, Yang L, Zhao SX, Dong M, Song HD. Tpo knockout in zebrafish partially recapitulates clinical manifestations of congenital hypothyroidism and reveals the involvement of TH in proper development of glucose homeostasis. Gen Comp Endocrinol 2022; 323-324:114033. [PMID: 35367205 DOI: 10.1016/j.ygcen.2022.114033] [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: 01/27/2022] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 11/26/2022]
Abstract
Congenital hypothyroidism (CH) is a highly prevalent but treatable neonatal endocrine disorder. Thyroid peroxidase (TPO) catalyzes key reactions in thyroid hormone (TH) synthesis. TPO mutations have been found to underlie approximately 5% of congenital hypothyroidism in Chinese patients with more severe phenotypes, the treatment of whom usually requires a higher dose of L-thyroxine. The Tpo gene of zebrafish has 66% homology with the human TPO gene, and synteny analysis has indicated that it is likely a human TPO ortholog. In this study, we generated a tpo-/- mutant zebrafish line through knockout of tpo with CRISPR/Cas9 and investigated the associated phenotypes. Tpo-/- mutant zebrafish displayed growth retardation; an increased number of thyroid follicular cells; and abnormal extrathyroidal phenotypes including pigmentation defects, erythema in the thoracic region, delayed scale development and failure of swim bladder secondary lobe formation. All these abnormal phenotypes were reversed by 30 nM thyroxine (T4) treatment starting at 1 month of age. Tpo-/- mutants also showed increased glucose levels during larval stages, and the increases were induced at least in part by increasing glucagon and decreasing insulin expression. Our work indicates that tpo-mutant zebrafish may serve as a human congenital hypothyroidism model for studying TPO- and TH-related disease mechanisms.
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Affiliation(s)
- Ya Fang
- Department of Molecular Diagnostics & Endocrinology, The Core Laboratory in Medical Center of Clinical Research, Shanghai Ninth People's Hospital, State Key Laboratory of Medical Genomics, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Jia-Ping Wan
- Department of Molecular Diagnostics & Endocrinology, The Core Laboratory in Medical Center of Clinical Research, Shanghai Ninth People's Hospital, State Key Laboratory of Medical Genomics, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Rui-Jia Zhang
- Renji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, China
| | - Feng Sun
- Department of Molecular Diagnostics & Endocrinology, The Core Laboratory in Medical Center of Clinical Research, Shanghai Ninth People's Hospital, State Key Laboratory of Medical Genomics, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Liu Yang
- Department of Molecular Diagnostics & Endocrinology, The Core Laboratory in Medical Center of Clinical Research, Shanghai Ninth People's Hospital, State Key Laboratory of Medical Genomics, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Shuang-Xia Zhao
- Department of Molecular Diagnostics & Endocrinology, The Core Laboratory in Medical Center of Clinical Research, Shanghai Ninth People's Hospital, State Key Laboratory of Medical Genomics, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Mei Dong
- Department of Molecular Diagnostics & Endocrinology, The Core Laboratory in Medical Center of Clinical Research, Shanghai Ninth People's Hospital, State Key Laboratory of Medical Genomics, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China.
| | - Huai-Dong Song
- Department of Molecular Diagnostics & Endocrinology, The Core Laboratory in Medical Center of Clinical Research, Shanghai Ninth People's Hospital, State Key Laboratory of Medical Genomics, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China.
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Oliveira PFD, Trindade BBS, Reis PFM, Santos TFDC, Alves JCS, Santana DSD, Badauê-Passos Jr D. The Induction of Hypothyroidism During Gestation Decreases Outer Hair Cell Motility in Rat Offspring. Int Arch Otorhinolaryngol 2022; 26:e712-e717. [DOI: 10.1055/s-0042-1745856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 03/01/2022] [Indexed: 10/18/2022] Open
Abstract
Abstract
Introduction Perinatal hypothyroidism has a negative repercussion on the development and maturation of auditory system function. However, its long-term effect on auditory function remains unsettled.
Objective To evaluate the effect of prenatal hypothyroidism on the auditory function of adult offspring in rats.
Methods Pregnant Wistar rats were given the antithyroid drug methimazole (0.02% -1-methylimidazole-2-thiol– MMI) in drinking water, ad libitum, from gestational day (GD) 9 to postnatal day 15 (PND15). Anesthetized offspring from MMI-treated dams (OMTD) and control rats were evaluated by tympanometry, distortion product otoacoustic emission (DPOAE), and auditory brainstem response (ABR) at PNDs 30, 60, 90, and 120.
Results Our data demonstrated no middle ear dysfunction, with the OMTD compliance lower than that of the control group. The DPOAE revealed the absence of outer hair cells function, and the ABR showed normal integrity of neural auditory pathways up to brainstem level in the central nervous system. Furthermore, in the OMTD group, hearing loss was characterized by a higher electrophysiological threshold.
Conclusion Our data suggest that perinatal hypothyroidism leads to irreversible damage to cochlear function in offspring.
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Affiliation(s)
- Priscila Feliciano de Oliveira
- Department of Health Sciences, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
- Department of Speech, Language and Hearing, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
- Department of Physiology, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | | | | | | | - Julio Cesar Santana Alves
- Department of Health Sciences, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
- Department of Veterinary Medicine, Faculdade Pio Décimo , Aracaju, SE, Brazil
- Department of Physiology, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | - Demetrius Silva de Santana
- Department of Physiology, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
- Department of Science Computation, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
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Chaulin AM, Grigorieva JV, Suvorova GN, Duplyakov DV. Experimental Modeling Of Hypothyroidism: Principles, Methods, Several Advanced Research Directions In Cardiology. RUSSIAN OPEN MEDICAL JOURNAL 2021. [DOI: 10.15275/rusomj.2021.0311] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Hypothyroidism is one of the most common pathological conditions in modern clinical practice. Due to the fact that the targets of thyroid hormones are virtually all organs and tissues, the morphological and clinical manifestations arising with a deficiency of thyroid hormones are quite diverse. Experimental models of hypothyroidism in laboratory animals are widely used for preclinical study of the fundamental pathophysiological mechanisms underlying hypothyroidism, as well as for assessing the effectiveness of treatment-and-prophylactic effects. Currently, several groups of effective models of hypothyroidism have been developed: dietary, surgical, medicamentous, genetic, radioactive and immunological. Each of the specified models is based on different principles, has advantages and disadvantages, and can be used depending on the goals and objectives of the experiment. In this review, we will consistently consider hypothyroidism modeling methods and indicate some promising areas of their use in cardiology.
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Affiliation(s)
- Aleksey M. Chaulin
- Samara State Medical University, Samara, Russia; Samara Regional Clinical Cardiological Dispensary, Samara, Russia
| | | | | | - Dmitry V. Duplyakov
- Samara State Medical University, Samara, Russia; Samara Regional Clinical Cardiological Dispensary, Samara, Russia
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Tobias L, Elias-Assad G, Khayat M, Admoni O, Almashanu S, Tenenbaum-Rakover Y. Long-Term Outcome of Patients with TPO Mutations. J Clin Med 2021; 10:3898. [PMID: 34501348 PMCID: PMC8432017 DOI: 10.3390/jcm10173898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/25/2021] [Accepted: 08/27/2021] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Thyroid peroxidase (TPO) deficiency is the most common enzymatic defect causing congenital hypothyroidism (CH). We aimed to characterize the long-term outcome of patients with TPO deficiency. METHODS Clinical and genetic data were collected retrospectively. RESULTS Thirty-three patients with primary CH caused by TPO deficiency were enrolled. The follow-up period was up to 43 years. Over time, 20 patients (61%) developed MNG. Eight patients (24%) underwent thyroidectomy: one of them had minimal invasive follicular thyroid carcinoma. No association was found between elevated lifetime TSH levels and the development of goiter over the years. CONCLUSIONS This cohort represents the largest long-term follow up of patients with TPO deficiency. Our results indicate that elevated TSH alone cannot explain the high rate of goiter occurrence in patients with TPO deficiency, suggesting additional factors in goiter development. The high rate of MNG development and the risk for thyroid carcinoma indicate a need for long-term follow up with annual ultrasound scans.
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Affiliation(s)
- Leraz Tobias
- Pediatric Department B, Ha’Emek Medical Center, Afula 1834111, Israel
| | - Ghadir Elias-Assad
- Pediatric Endocrine Institute, Ha’Emek Medical Center, Afula 1834111, Israel; (G.E.-A.); (O.A.); (Y.T.-R.)
- Technion Institute of Technology, Rappaport Faculty of Medicine, Haifa 3200003, Israel
| | - Morad Khayat
- Genetic Institute, Ha’Emek Medical Center, Afula 1834111, Israel;
| | - Osnat Admoni
- Pediatric Endocrine Institute, Ha’Emek Medical Center, Afula 1834111, Israel; (G.E.-A.); (O.A.); (Y.T.-R.)
| | - Shlomo Almashanu
- The National Newborn Screening Program, Ministry of Health, Tel-Hashomer, Ramat Gan 5262100, Israel;
| | - Yardena Tenenbaum-Rakover
- Pediatric Endocrine Institute, Ha’Emek Medical Center, Afula 1834111, Israel; (G.E.-A.); (O.A.); (Y.T.-R.)
- Technion Institute of Technology, Rappaport Faculty of Medicine, Haifa 3200003, Israel
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Almagor T, Rath S, Nachtigal D, Sharroni Z, Elias-Assad G, Hess O, Havazelet G, Zehavi Y, Spiegel R, Bercovich D, Almashanu S, Tenenbaum-Rakover Y. High Prevalence of Hearing Impairment in Primary Congenital Hypothyroidism. Eur Thyroid J 2021; 10:215-221. [PMID: 34178707 PMCID: PMC8216036 DOI: 10.1159/000509775] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/28/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND An association between hearing impairment (HI) and congenital hypothyroidism (CH) has been reported previously. However, in general, studies were retrospective and had small sample sizes, and the results were variable and inconclusive. The aim of our study was to assess the prevalence of HI among patients with CH and to examine factors potentially predictive of HI including severity of CH, etiology of CH, and timing of treatment initiation. METHODS Audiometry was undertaken prospectively in 66 patients aged 3-21 years diagnosed with primary CH and 49 healthy matched controls. All patients with HI underwent examination by an otolaryngologist, and in patients with sensorineural loss, brainstem evoked response audiometry was performed. A next-generation sequencing (NGS) panel for genes involved in deafness was performed in patients with sensorineural HI to exclude additional genetic etiologies. RESULTS HI was found in 19 patients (28.7%). Among them, 5 (7.6%) had moderate to severe bilateral sensorineural impairment and 14 (21.2%) had mild conductive HI. Conductive HI was bilateral in 5 of these patients (36%). None of the controls had HI. No specific etiology was found in patients with HI, and no differences were identified in age at diagnosis, age at initiation of levothyroxine (LT4) therapy, gender, or ethnicity between patients with and without HI. A nonsignificant trend toward lower mean screening TT4 levels was found in patients with HI (compared to those without HI) (3.42 vs. 5.34 μg/dL, p = 0.095). No pathogenic variants in genes attributed to HI were identified by NGS in the 5 patients with sensorineural deafness, indicating that HI in these patients was likely attributable to CH rather than other genetic etiologies. CONCLUSIONS Our findings indicate a high prevalence of HI among patients with CH, predominantly of the conductive type. HI was not associated with the etiology of CH or with delayed initiation of LT4 therapy. Audiometry is recommended for children diagnosed with CH and repeat monitoring may be warranted to identify acquired HI and to prevent long-term sequelae of undiagnosed deafness.
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Affiliation(s)
- Tal Almagor
- Pediatric Endocrine Institute, Ha'Emek Medical Center, Afula, Israel
- Pediatric Department B, Ha'Emek Medical Center, Afula, Israel
- Rappaport Faculty of Medicine, Technion − Israel Institute of Technology, Haifa, Israel
| | - Shoshana Rath
- Pediatric Endocrine Institute, Ha'Emek Medical Center, Afula, Israel
| | - Dan Nachtigal
- Department of Otolaryngology, Head and Neck Surgery, Ha'Emek Medical Center, Afula, Israel
| | - Zohara Sharroni
- Department of Otolaryngology, Head and Neck Surgery, Ha'Emek Medical Center, Afula, Israel
| | - Ghadir Elias-Assad
- Pediatric Endocrine Institute, Ha'Emek Medical Center, Afula, Israel
- Rappaport Faculty of Medicine, Technion − Israel Institute of Technology, Haifa, Israel
| | - Ora Hess
- Pediatric Endocrine Institute, Ha'Emek Medical Center, Afula, Israel
| | | | - Yoav Zehavi
- Pediatric Department B, Ha'Emek Medical Center, Afula, Israel
| | - Ronen Spiegel
- Pediatric Department B, Ha'Emek Medical Center, Afula, Israel
- Rappaport Faculty of Medicine, Technion − Israel Institute of Technology, Haifa, Israel
| | - Dani Bercovich
- Faculty of Medical Science, Tel Hai Academic College Upper Galilee, Tel Hai, Israel
- GGA − Galil Genetic Analysis Laboratory Ltd., Kazerin, Israel
| | - Shlomo Almashanu
- The National Newborn Screening Program, Ministry of Health, Tel-HaShomer, Israel
| | - Yardena Tenenbaum-Rakover
- Pediatric Endocrine Institute, Ha'Emek Medical Center, Afula, Israel
- Rappaport Faculty of Medicine, Technion − Israel Institute of Technology, Haifa, Israel
- *Yardena Tenenbaum-Rakover, Pediatric Endocrine Institute, Ha'Emek Medical Center, 24 Yitzhak Rabin Ave., Afula 1834111 (Israel),
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Zhu Y, Bing D, Wang D, Zhao L, Yin Z, Zhang Q, Guan J, Wang Q. Analysis of thyroid dysfunction in patients with sudden sensorineural hearing loss. World J Otorhinolaryngol Head Neck Surg 2020; 7:1-8. [PMID: 33474537 PMCID: PMC7801234 DOI: 10.1016/j.wjorl.2019.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 02/12/2019] [Accepted: 02/19/2019] [Indexed: 11/30/2022] Open
Abstract
Background Sudden sensorineural hearing loss (SSHL) refers to the sudden occurrence of unexplained sensorineural hearing loss. The present study showed that different systemic diseases had different influence on the occurrence and hearing outcome of SSHL. Thyroid hormone is one of the important factors for the development of fetal ear and auditory function. However, the distribution of thyroid dysfunction in SSHL patients and the effect of thyroid dysfunction on the occurrence and hearing outcome of SSHL has not been studied. Methods In this study, a retrospective analysis had been done in 676 patients with SSHL. We had described the distribution of thyroid function in patients with SSHL in detail, and by the statistical method, analyzed the relationship between the hearing outcome and thyroid dysfunction, respectively. Results In all patients, 24.41% (165/676) had abnormal thyroid function testing results. The onset age of SSHL in FT3 abnormal group (including low and high group) was younger than that in normal FT3 group. Recovery group had more patients with lower-than-normal T3 level as compared to non-recovery patients. Significant associations between T3 levels and hearing outcome were observed in the subgroup with longer time elapse between symptom onset and treatment (≥14 d). Conclusion The incidence of thyroid dysfunction in SSHL is significantly higher than in the general population. There was obvious relationship between T3 and FT3 item of thyroid dysfunction and the onset time and hearing outcome of SSHL, which indicated that T3 or FT3 indicator may be one of the affecting factors for the SSHL. Early screening and diagnosis of thyroid dysfunction, especial T3 level, may help to evaluate the prognosis in SSHL patients.
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Affiliation(s)
- Yuhua Zhu
- Department of Otolaryngology Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, 100853, China.,Department of Otolaryngology Head and Neck Surgery, Hainan Hospital of Chinese PLA General Hospital, Hainan, 572013, China
| | - Dan Bing
- Department of Otolaryngology-Head and Neck Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Dayong Wang
- Department of Otolaryngology Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Lidong Zhao
- Department of Otolaryngology Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Zifang Yin
- Department of Otolaryngology Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Qiujing Zhang
- Department of Otolaryngology Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Jing Guan
- Department of Otolaryngology Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Qiuju Wang
- Department of Otolaryngology Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, 100853, China
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Löf C, Patyra K, Kero A, Kero J. Genetically modified mouse models to investigate thyroid development, function and growth. Best Pract Res Clin Endocrinol Metab 2018; 32:241-256. [PMID: 29779579 DOI: 10.1016/j.beem.2018.03.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The thyroid gland produces thyroid hormones (TH), which are essential regulators for growth, development and metabolism. The thyroid is mainly controlled by the thyroid-stimulating hormone (TSH) that binds to its receptor (TSHR) on thyrocytes and mediates its action via different G protein-mediated signaling pathways. TSH primarily activates the Gs-pathway, and at higher concentrations also the Gq/11-pathway, leading to an increase of intracellular cAMP and Ca2+, respectively. To date, the physiological importance of other G protein-mediated signaling pathways in thyrocytes is unclear. Congenital hypothyroidism (CH) is defined as the lack of TH at birth. In familial cases, high-throughput sequencing methods have facilitated the identification of novel mutations. Nevertheless, the precise etiology of CH yet remains unraveled in a proportion of cases. Genetically modified mouse models can reveal new pathophysiological mechanisms of thyroid diseases. Here, we will present an overview of genetic mouse models for thyroid diseases, which have provided crucial insights into thyroid gland development, function, and growth with a special focus on TSHR and microRNA signaling.
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Affiliation(s)
- C Löf
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland
| | - K Patyra
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland
| | - A Kero
- Department of Pediatrics, Turku University Hospital, Kiinamyllynkatu 4-8, 20521, Turku, Finland
| | - J Kero
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland; Department of Pediatrics, Turku University Hospital, Kiinamyllynkatu 4-8, 20521, Turku, Finland.
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Generation and characterization of a hypothyroidism rat model with truncated thyroid stimulating hormone receptor. Sci Rep 2018; 8:4004. [PMID: 29507327 PMCID: PMC5838214 DOI: 10.1038/s41598-018-22405-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 02/22/2018] [Indexed: 11/13/2022] Open
Abstract
Thyroid stimulating hormone receptor (TSHR), a G-protein-coupled receptor, is important for thyroid development and growth. In several cases, frameshift and/or nonsense mutations in TSHR were found in the patients with congenital hypothyroidism (CH), however they have not been functionally studied in an animal model. In the present work, we generated a unique TshrDf/Df rat model that recapitulates the phenotypes in TSHR Y444X patient by CRISPR/Cas genome editing technology. In this rat model, TSHR is truncated at the second transmembrane domain, leading to CH phenotypes as what was observed in the patients, including dwarf, thyroid aplasia, infertility, TSH resistant as well as low serum thyroid hormone levels. The phenotypes can be reversed, at least partially, by levothyroxine (L-T4) treatment after weaning. The thyroid development is severely impaired in the TshrDf/Df rats due to the suppression of the thyroid specific genes, i.e., thyroperoxidase (Tpo), thyroglobulin (Tg) and sodium iodide symporter (Nis), at both mRNA and protein levels. In conclusion, the TshrDf/Df rat serves as a brand new genetic model to study CH in human, and will greatly help to shed light into the development of terminal organs that are sensitive to thyroid hormones.
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Ng L, Cordas E, Wu X, Vella KR, Hollenberg AN, Forrest D. Age-Related Hearing Loss and Degeneration of Cochlear Hair Cells in Mice Lacking Thyroid Hormone Receptor β1. Endocrinology 2015; 156:3853-65. [PMID: 26241124 PMCID: PMC4588828 DOI: 10.1210/en.2015-1468] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A key function of the thyroid hormone receptor β (Thrb) gene is in the development of auditory function. However, the roles of the 2 receptor isoforms, TRβ1 and TRβ2, expressed by the Thrb gene are unclear, and it is unknown whether these isoforms promote the maintenance as well as development of hearing. We investigated the function of TRβ1 in mice with a Thrb(b1) reporter allele that expresses β-galactosidase instead of TRβ1. In the immature cochlea, β-galactosidase was detected in the greater epithelial ridge, sensory hair cells, spiral ligament, and spiral ganglion and in adulthood, at low levels in the hair cells, support cells and root cells of the outer sulcus. Although deletion of all TRβ isoforms causes severe, early-onset deafness, deletion of TRβ1 or TRβ2 individually caused no obvious hearing loss in juvenile mice. However, over subsequent months, TRβ1 deficiency resulted in progressive loss of hearing and loss of hair cells. TRβ1-deficient mice had minimal changes in serum thyroid hormone and thyrotropin levels, indicating that hormonal imbalances were unlikely to cause hearing loss. The results suggest mutually shared roles for TRβ1 and TRβ2 in cochlear development and an unexpected requirement for TRβ1 in the maintenance of hearing in adulthood.
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Affiliation(s)
- Lily Ng
- Laboratory of Endocrinology and Receptor Biology (L.N., E.C., X.W., D.F.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892; and Division of Endocrinology, Diabetes and Metabolism (K.R.V., A.N.H.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Emily Cordas
- Laboratory of Endocrinology and Receptor Biology (L.N., E.C., X.W., D.F.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892; and Division of Endocrinology, Diabetes and Metabolism (K.R.V., A.N.H.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Xuefeng Wu
- Laboratory of Endocrinology and Receptor Biology (L.N., E.C., X.W., D.F.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892; and Division of Endocrinology, Diabetes and Metabolism (K.R.V., A.N.H.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Kristen R Vella
- Laboratory of Endocrinology and Receptor Biology (L.N., E.C., X.W., D.F.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892; and Division of Endocrinology, Diabetes and Metabolism (K.R.V., A.N.H.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Anthony N Hollenberg
- Laboratory of Endocrinology and Receptor Biology (L.N., E.C., X.W., D.F.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892; and Division of Endocrinology, Diabetes and Metabolism (K.R.V., A.N.H.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Douglas Forrest
- Laboratory of Endocrinology and Receptor Biology (L.N., E.C., X.W., D.F.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892; and Division of Endocrinology, Diabetes and Metabolism (K.R.V., A.N.H.), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
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