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García-Mato Á, Cervantes B, Murillo-Cuesta S, Rodríguez-de la Rosa L, Varela-Nieto I. Insulin-like Growth Factor 1 Signaling in Mammalian Hearing. Genes (Basel) 2021; 12:genes12101553. [PMID: 34680948 PMCID: PMC8535591 DOI: 10.3390/genes12101553] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 02/06/2023] Open
Abstract
Insulin-like growth factor 1 (IGF-1) is a peptide hormone belonging to the insulin family of proteins. Almost all of the biological effects of IGF-1 are mediated through binding to its high-affinity tyrosine kinase receptor (IGF1R), a transmembrane receptor belonging to the insulin receptor family. Factors, receptors and IGF-binding proteins form the IGF system, which has multiple roles in mammalian development, adult tissue homeostasis, and aging. Consequently, mutations in genes of the IGF system, including downstream intracellular targets, underlie multiple common pathologies and are associated with multiple rare human diseases. Here we review the contribution of the IGF system to our understanding of the molecular and genetic basis of human hearing loss by describing, (i) the expression patterns of the IGF system in the mammalian inner ear; (ii) downstream signaling of IGF-1 in the hearing organ; (iii) mouse mutations in the IGF system, including upstream regulators and downstream targets of IGF-1 that inform cochlear pathophysiology; and (iv) human mutations in these genes causing hearing loss.
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Affiliation(s)
- Ángela García-Mato
- Institute for Biomedical Research “Alberto Sols” (IIBm), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), 28029 Madrid, Spain; (Á.G.-M.); (B.C.); (S.M.-C.)
- Rare Diseases Networking Biomedical Research Centre (CIBERER), CIBER, Carlos III Institute of Health, 28029 Madrid, Spain
| | - Blanca Cervantes
- Institute for Biomedical Research “Alberto Sols” (IIBm), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), 28029 Madrid, Spain; (Á.G.-M.); (B.C.); (S.M.-C.)
- Rare Diseases Networking Biomedical Research Centre (CIBERER), CIBER, Carlos III Institute of Health, 28029 Madrid, Spain
| | - Silvia Murillo-Cuesta
- Institute for Biomedical Research “Alberto Sols” (IIBm), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), 28029 Madrid, Spain; (Á.G.-M.); (B.C.); (S.M.-C.)
- Rare Diseases Networking Biomedical Research Centre (CIBERER), CIBER, Carlos III Institute of Health, 28029 Madrid, Spain
- La Paz Hospital Institute for Health Research (IdiPAZ), 28046 Madrid, Spain
| | - Lourdes Rodríguez-de la Rosa
- Rare Diseases Networking Biomedical Research Centre (CIBERER), CIBER, Carlos III Institute of Health, 28029 Madrid, Spain
- La Paz Hospital Institute for Health Research (IdiPAZ), 28046 Madrid, Spain
- Correspondence: (L.R.-d.l.R.); (I.V.-N.)
| | - Isabel Varela-Nieto
- Institute for Biomedical Research “Alberto Sols” (IIBm), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), 28029 Madrid, Spain; (Á.G.-M.); (B.C.); (S.M.-C.)
- Rare Diseases Networking Biomedical Research Centre (CIBERER), CIBER, Carlos III Institute of Health, 28029 Madrid, Spain
- La Paz Hospital Institute for Health Research (IdiPAZ), 28046 Madrid, Spain
- Correspondence: (L.R.-d.l.R.); (I.V.-N.)
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Age-related hearing loss pertaining to potassium ion channels in the cochlea and auditory pathway. Pflugers Arch 2020; 473:823-840. [PMID: 33336302 PMCID: PMC8076138 DOI: 10.1007/s00424-020-02496-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/27/2020] [Accepted: 11/10/2020] [Indexed: 12/12/2022]
Abstract
Age-related hearing loss (ARHL) is the most prevalent sensory deficit in the elderly and constitutes the third highest risk factor for dementia. Lifetime noise exposure, genetic predispositions for degeneration, and metabolic stress are assumed to be the major causes of ARHL. Both noise-induced and hereditary progressive hearing have been linked to decreased cell surface expression and impaired conductance of the potassium ion channel KV7.4 (KCNQ4) in outer hair cells, inspiring future therapies to maintain or prevent the decline of potassium ion channel surface expression to reduce ARHL. In concert with KV7.4 in outer hair cells, KV7.1 (KCNQ1) in the stria vascularis, calcium-activated potassium channels BK (KCNMA1) and SK2 (KCNN2) in hair cells and efferent fiber synapses, and KV3.1 (KCNC1) in the spiral ganglia and ascending auditory circuits share an upregulated expression or subcellular targeting during final differentiation at hearing onset. They also share a distinctive fragility for noise exposure and age-dependent shortfalls in energy supply required for sustained surface expression. Here, we review and discuss the possible contribution of select potassium ion channels in the cochlea and auditory pathway to ARHL. We postulate genes, proteins, or modulators that contribute to sustained ion currents or proper surface expressions of potassium channels under challenging conditions as key for future therapies of ARHL.
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Genetic variation in thyroid folliculogenesis influences susceptibility to hypothyroidism-induced hearing impairment. Mamm Genome 2019; 30:5-22. [PMID: 30778664 DOI: 10.1007/s00335-019-09792-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 01/09/2019] [Indexed: 10/27/2022]
Abstract
Maternal and fetal sources of thyroid hormone are important for the development of many organ systems. Thyroid hormone deficiency causes variable intellectual disability and hearing impairment in mouse and man, but the basis for this variation is not clear. To explore this variation, we studied two thyroid hormone-deficient mouse mutants with mutations in pituitary-specific transcription factors, POU1F1 and PROP1, that render them unable to produce thyroid stimulating hormone. DW/J-Pou1f1dw/dw mice have profound deafness and both neurosensory and conductive hearing impairment, while DF/B-Prop1df/df mice have modest elevations in hearing thresholds consistent with developmental delay, eventually achieving normal hearing ability. The thyroid glands of Pou1f1 mutants are more severely affected than those of Prop1df/df mice, and they produce less thyroglobulin during the neonatal period critical for establishing hearing. We previously crossed DW/J-Pou1f1dw/+ and Cast/Ei mice and mapped a major locus on Chromosome 2 that protects against hypothyroidism-induced hearing impairment in Pou1f1dw/dw mice: modifier of dw hearing (Mdwh). Here we refine the location of Mdwh by genotyping 196 animals with 876 informative SNPs, and we conduct novel mapping with a DW/J-Pou1f1dw/+ and 129/P2 cross that reveals 129/P2 mice also have a protective Mdwh locus. Using DNA sequencing of DW/J and DF/B strains, we determined that the genes important for thyroid gland function within Mdwh vary in amino acid sequence between strains that are susceptible or resistant to hypothyroidism-induced hearing impairment. These results suggest that the variable effects of congenital hypothyroidism on the development of hearing ability are attributable to genetic variation in postnatal thyroid gland folliculogenesis and function.
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Sundaresan S, Balasubbu S, Mustapha M. Thyroid hormone is required for the pruning of afferent type II spiral ganglion neurons in the mouse cochlea. Neuroscience 2015; 312:165-78. [PMID: 26592716 DOI: 10.1016/j.neuroscience.2015.11.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 11/09/2015] [Accepted: 11/10/2015] [Indexed: 12/13/2022]
Abstract
Afferent connections to the sensory inner (IHCs) and outer hair cells (OHCs) in the cochlea refine and functionally mature during the thyroid hormone (TH)-critical period of inner ear development that occurs perinatally in rodents. In this study, we investigated the effects of hypothyroidism on afferent type II innervation to outer hair cells using the Snell dwarf mouse (Pit1(dw)). Using a transgenic approach to specifically label type II spiral ganglion neurons (SGNs), we found that lack of TH causes persistence of excess type II SGN connections to the OHCs, as well as continued expression of the hair cell functional marker, otoferlin (OTOF), in the OHCs beyond the maturation period. We also observed a concurrent delay in efferent attachment to the OHCs. Supplementing with TH during the early postnatal period from postnatal day (P) 3 to P4 reversed the defect in type II SGN pruning but did not alter OTOF expression. Our results show that hypothyroidism causes a defect in the large-scale pruning of afferent type II SGNs in the cochlea, and a delay in efferent attachment and the maturation of OTOF expression. Our data suggest that the state of maturation of hair cells, as determined by OTOF expression, may not regulate the pruning of their afferent innervation.
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Affiliation(s)
- S Sundaresan
- Department of Otolaryngology-Head & Neck Surgery, 300 Pasteur Drive, Stanford University, Stanford, CA 94035, United States
| | - S Balasubbu
- Department of Otolaryngology-Head & Neck Surgery, 300 Pasteur Drive, Stanford University, Stanford, CA 94035, United States
| | - M Mustapha
- Department of Otolaryngology-Head & Neck Surgery, 300 Pasteur Drive, Stanford University, Stanford, CA 94035, United States.
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Rodríguez-de la Rosa L, Sánchez-Calderón H, Contreras J, Murillo-Cuesta S, Falagan S, Avendaño C, Dopazo J, Varela-Nieto I, Milo M. Comparative gene expression study of the vestibular organ of the Igf1 deficient mouse using whole-transcript arrays. Hear Res 2015; 330:62-77. [PMID: 26341476 DOI: 10.1016/j.heares.2015.08.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 08/27/2015] [Accepted: 08/28/2015] [Indexed: 10/23/2022]
Abstract
The auditory and vestibular organs form the inner ear and have a common developmental origin. Insulin like growth factor 1 (IGF-1) has a central role in the development of the cochlea and maintenance of hearing. Its deficiency causes sensorineural hearing loss in man and mice. During chicken early development, IGF-1 modulates neurogenesis of the cochleovestibular ganglion but no further studies have been conducted to explore the potential role of IGF-1 in the vestibular system. In this study we have compared the whole transcriptome of the vestibular organ from wild type and Igf1(-/-) mice at different developmental and postnatal times. RNA was prepared from E18.5, P15 and P90 vestibular organs of Igf1(-/-) and Igf1(+/+) mice and the transcriptome analysed in triplicates using Affymetrix(®) Mouse Gene 1.1 ST Array Plates. These plates are whole-transcript arrays that include probes to measure both messenger (mRNA) and long intergenic non-coding RNA transcripts (lincRNA), with a coverage of over 28 thousand coding transcripts and over 7 thousands non-coding transcripts. Given the complexity of the data we used two different methods VSN-RMA and mmBGX to analyse and compare the data. This is to better evaluate the number of false positives and to quantify uncertainty of low signals. We identified a number of differentially expressed genes that we described using functional analysis and validated using RT-qPCR. The morphology of the vestibular organ did not show differences between genotypes and no evident alterations were observed in the vestibular sensory areas of the null mice. However, well-defined cellular alterations were found in the vestibular neurons with respect their number and size. Although these mice did not show a dramatic vestibular phenotype, we conducted a functional analysis on differentially expressed genes between genotypes and across time. This was with the aim to identify new pathways that are involved in the development of the vestibular organ as well as pathways that maybe affected by the lack of IGF-1 and be associated to the morphological changes of the vestibular neurons that we observed in the Igf1(-/-) mice.
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Affiliation(s)
- Lourdes Rodríguez-de la Rosa
- Neurobiology of Hearing, Department of Endocrine and Nervous System Pathophysiology, Alberto Sols Biomedical Research Institute (IIBM), CSIC-UAM, Madrid, Spain; Biomedical Research Networking Center on Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Madrid, Spain; IdiPAZ Institute for Health Research, Madrid, Spain
| | - Hortensia Sánchez-Calderón
- Neurobiology of Hearing, Department of Endocrine and Nervous System Pathophysiology, Alberto Sols Biomedical Research Institute (IIBM), CSIC-UAM, Madrid, Spain
| | - Julio Contreras
- Neurobiology of Hearing, Department of Endocrine and Nervous System Pathophysiology, Alberto Sols Biomedical Research Institute (IIBM), CSIC-UAM, Madrid, Spain; Biomedical Research Networking Center on Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Madrid, Spain; Department of Anatomy, Faculty of Veterinary, Complutense University, Madrid, Spain
| | - Silvia Murillo-Cuesta
- Neurobiology of Hearing, Department of Endocrine and Nervous System Pathophysiology, Alberto Sols Biomedical Research Institute (IIBM), CSIC-UAM, Madrid, Spain; Biomedical Research Networking Center on Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Madrid, Spain; IdiPAZ Institute for Health Research, Madrid, Spain
| | - Sandra Falagan
- Department of Anatomy, Faculty of Medicine, Autonomous University, Madrid, Spain
| | - Carlos Avendaño
- IdiPAZ Institute for Health Research, Madrid, Spain; Department of Anatomy, Faculty of Medicine, Autonomous University, Madrid, Spain
| | - Joaquín Dopazo
- Biomedical Research Networking Center on Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Madrid, Spain; Department of Computational Genomics, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Isabel Varela-Nieto
- Neurobiology of Hearing, Department of Endocrine and Nervous System Pathophysiology, Alberto Sols Biomedical Research Institute (IIBM), CSIC-UAM, Madrid, Spain; Biomedical Research Networking Center on Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Madrid, Spain; IdiPAZ Institute for Health Research, Madrid, Spain
| | - Marta Milo
- Department of Biomedical Science, University of Sheffield, Sheffield, UK.
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Zhang X, Wu X, Jia W, Pan C, Li X, Lei C, Chen H, Lan X. Novel Nucleotide Variations, Haplotypes Structure and Associations with Growth Related Traits of Goat AT Motif-Binding Factor (ATBF1) Gene. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2015; 28:1394-406. [PMID: 26323396 PMCID: PMC4554846 DOI: 10.5713/ajas.14.0860] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 03/11/2015] [Accepted: 04/01/2015] [Indexed: 01/05/2023]
Abstract
The AT motif-binding factor (ATBF1) not only interacts with protein inhibitor of activated signal transducer and activator of transcription 3 (STAT3) (PIAS3) to suppress STAT3 signaling regulating embryo early development and cell differentiation, but is required for early activation of the pituitary specific transcription factor 1 (Pit1) gene (also known as POU1F1) critically affecting mammalian growth and development. The goal of this study was to detect novel nucleotide variations and haplotypes structure of the ATBF1 gene, as well as to test their associations with growth-related traits in goats. Herein, a total of seven novel single nucleotide polymorphisms (SNPs) (SNP 1-7) within this gene were found in two well-known Chinese native goat breeds. Haplotypes structure analysis demonstrated that there were four haplotypes in Hainan black goat while seventeen haplotypes in Xinong Saanen dairy goat, and both breeds only shared one haplotype (hap1). Association testing revealed that the SNP2, SNP5, SNP6, and SNP7 loci were also found to significantly associate with growth-related traits in goats, respectively. Moreover, one diplotype in Xinong Saanen dairy goats significantly linked to growth related traits. These preliminary findings not only would extend the spectrum of genetic variations of the goat ATBF1 gene, but also would contribute to implementing marker-assisted selection in genetics and breeding in goats.
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Affiliation(s)
- Xiaoyan Zhang
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xianfeng Wu
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Wenchao Jia
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Chuanying Pan
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xiangcheng Li
- Institute of Beijing Animal Science and Veterinary, Chinese Academy of Agricultural Science, Beijing 100194, China
| | - Chuzhao Lei
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Hong Chen
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xianyong Lan
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
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Nishio SY, Hattori M, Moteki H, Tsukada K, Miyagawa M, Naito T, Yoshimura H, Iwasa YI, Mori K, Shima Y, Sakuma N, Usami SI. Gene expression profiles of the cochlea and vestibular endorgans: localization and function of genes causing deafness. Ann Otol Rhinol Laryngol 2015; 124 Suppl 1:6S-48S. [PMID: 25814645 DOI: 10.1177/0003489415575549] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES We sought to elucidate the gene expression profiles of the causative genes as well as the localization of the encoded proteins involved in hereditary hearing loss. METHODS Relevant articles (as of September 2014) were searched in PubMed databases, and the gene symbols of the genes reported to be associated with deafness were located on the Hereditary Hearing Loss Homepage using localization, expression, and distribution as keywords. RESULTS Our review of the literature allowed us to systematize the gene expression profiles for genetic deafness in the inner ear, clarifying the unique functions and specific expression patterns of these genes in the cochlea and vestibular endorgans. CONCLUSIONS The coordinated actions of various encoded molecules are essential for the normal development and maintenance of auditory and vestibular function.
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Affiliation(s)
- Shin-Ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Mitsuru Hattori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hideaki Moteki
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Keita Tsukada
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Maiko Miyagawa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Takehiko Naito
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hidekane Yoshimura
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yoh-Ichiro Iwasa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Kentaro Mori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yutaka Shima
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Naoko Sakuma
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Otorhinolaryngology and Head and Neck Surgery, Yokohama City University School of Medicine, Yokohama, Japan
| | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
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Calton MA, Lee D, Sundaresan S, Mendus D, Leu R, Wangsawihardja F, Johnson KR, Mustapha M. A lack of immune system genes causes loss in high frequency hearing but does not disrupt cochlear synapse maturation in mice. PLoS One 2014; 9:e94549. [PMID: 24804771 PMCID: PMC4012943 DOI: 10.1371/journal.pone.0094549] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 03/18/2014] [Indexed: 12/12/2022] Open
Abstract
Early cochlear development is marked by an exuberant outgrowth of neurites that innervate multiple targets. The establishment of mature cochlear neural circuits is, however, dependent on the pruning of inappropriate axons and synaptic connections. Such refinement also occurs in the central nervous system (CNS), and recently, genes ordinarily associated with immune and inflammatory processes have been shown to play roles in synaptic pruning in the brain. These molecules include the major histocompatibility complex class I (MHCI) genes, H2-Kb and H2-Db, and the complement cascade gene, C1qa. Since the mechanisms involved in synaptic refinement in the cochlea are not well understood, we investigated whether these immune system genes may be involved in this process and whether they are required for normal hearing function. Here we report that these genes are not necessary for normal synapse formation and refinement in the mouse cochlea. We further demonstrate that C1qa expression is not necessary for normal hearing in mice but the lack of expression of H2-Kb and H2-Db causes hearing impairment. These data underscore the importance of the highly polymorphic family of MHCI genes in hearing in mice and also suggest that factors and mechanisms regulating synaptic refinement in the cochlea may be distinct from those in the CNS.
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Affiliation(s)
- Melissa A. Calton
- Department of Otolaryngology-Head & Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Dasom Lee
- Department of Otolaryngology-Head & Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Srividya Sundaresan
- Department of Otolaryngology-Head & Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Diana Mendus
- Department of Otolaryngology-Head & Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Rose Leu
- Department of Otolaryngology-Head & Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Felix Wangsawihardja
- Department of Otolaryngology-Head & Neck Surgery, Stanford University, Stanford, California, United States of America
| | | | - Mirna Mustapha
- Department of Otolaryngology-Head & Neck Surgery, Stanford University, Stanford, California, United States of America
- * E-mail:
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Atrophic thyroid follicles and inner ear defects reminiscent of cochlear hypothyroidism in Slc26a4-related deafness. Mamm Genome 2014; 25:304-16. [PMID: 24760582 DOI: 10.1007/s00335-014-9515-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 04/03/2014] [Indexed: 01/10/2023]
Abstract
Thyroid hormone is essential for inner ear development and is required for auditory system maturation. Human mutations in SLC26A4 lead to a syndromic form of deafness with enlargement of the thyroid gland (Pendred syndrome) and non-syndromic deafness (DFNB4). We describe mice with an Slc26a4 mutation, Slc26a4 (loop/loop) , which are profoundly deaf but show a normal sized thyroid gland, mimicking non-syndromic clinical signs. Histological analysis of the thyroid gland revealed defective morphology, with a majority of atrophic microfollicles, while measurable thyroid hormone in blood serum was within the normal range. Characterization of the inner ear showed a spectrum of morphological and molecular defects consistent with inner ear pathology, as seen in hypothyroidism or disrupted thyroid hormone action. The pathological inner ear hallmarks included thicker tectorial membrane with reduced β-tectorin protein expression, the absence of BK channel expression of inner hair cells, and reduced inner ear bone calcification. Our study demonstrates that deafness in Slc26a4 (loop/loop) mice correlates with thyroid pathology, postulating that sub-clinical thyroid morphological defects may be present in some DFNB4 individuals with a normal sized thyroid gland. We propose that insufficient availability of thyroid hormone during inner ear development plays an important role in the mechanism underlying deafness as a result of SLC26A4 mutations.
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Johnson KR, Gagnon LH, Longo-Guess CM, Harris BS, Chang B. Hearing impairment in hypothyroid dwarf mice caused by mutations of the thyroid peroxidase gene. J Assoc Res Otolaryngol 2013; 15:45-55. [PMID: 24297261 DOI: 10.1007/s10162-013-0427-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 11/05/2013] [Indexed: 12/26/2022] Open
Abstract
Thyroid hormone (TH) is essential for proper cochlear development and function, and TH deficiencies cause variable hearing impairment in humans and mice. Thyroid peroxidase (TPO) catalyzes key reactions in TH synthesis, and TPO mutations have been found to underlie many cases of congenital hypothyroidism in human patients. In contrast, only a single mutation of the mouse TPO gene has been reported previously (Tpo(R479C)) but was not evaluated for auditory function. Here, we describe and characterize two new mouse mutations of Tpo with an emphasis on their associated auditory deficits. Mice homozygous for these recessive mutations have dysplastic thyroid glands and lack detectable levels of TH. Because of the small size of mutant mice, the mutations were named teeny (symbol Tpo(tee)) and teeny-2 Jackson (Tpo(tee-2J)). Tpo(tee) is a single base-pair missense mutation that was induced by ENU, and Tpo(tee-2J) is a 64 bp intragenic deletion that arose spontaneously. The Tpo(tee) mutation changes the codon for a highly conserved tyrosine to asparagine (p.Y614N), and the Tpo(tee-2J) mutation deletes a splice donor site, which results in exon skipping and aberrant transcripts. Mutant mice are profoundly hearing impaired with auditory brainstem response (ABR) thresholds about 60 dB above those of non-mutant controls. The maturation of cochlear structures is delayed in mutant mice and tectorial membranes are abnormally thick. To evaluate the effect of genetic background on auditory phenotype, we produced a C3.B6-Tpo(tee-2J) congenic strain and found that ABR thresholds of mutant mice on the C3H/HeJ strain background are 10-12 dB lower than those of mutant mice on the C57BL/6 J background. The Tpo mutant strains described here provide new heritable mouse models of congenital hypothyroidism that will be valuable for future studies of thyroid hormones' role in auditory development and function.
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Affiliation(s)
- Kenneth R Johnson
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME, 04609, USA,
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Abstract
The senses are our window to the world, our interface with the habitat in which we live in and the basis for our communication with each other. Although sensory systems are not generally viewed as major targets of endocrine regulation, sensory development is profoundly influenced by thyroid hormone (T(3)) signalling. In this article, we discuss this developmental role of T(3) and highlight the auditory system as the best-studied example of the interplay between systemic and local tissue mechanisms by which T(3) stimulates the onset of sensory function. Several genes that mediate the action of T(3) are known to promote sensory development in mice, including genes that encode T(3) receptors and deiodinase enzymes that amplify or deplete levels of T(3). We also discuss the current knowledge of sensory defects in human genetic disorders in which T(3) signalling is impaired. As sensory input provides the only means of acquiring information from the environment, the stimulation of sensory development is one of the most fundamental functions of T(3) signalling.
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Affiliation(s)
- Lily Ng
- National Institute of Diabetes and Digestive and Kidney Disease, Laboratory of Endocrinology and Receptor Biology, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
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