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Hosoya M, Fujioka M, Kobayashi R, Okano H, Ogawa K. Overlapping expression of anion exchangers in the cochlea of a non-human primate suggests functional compensation. Neurosci Res 2016; 110:1-10. [PMID: 27091614 DOI: 10.1016/j.neures.2016.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/27/2016] [Accepted: 04/05/2016] [Indexed: 11/19/2022]
Abstract
Ion homeostasis in the inner ear is essential for proper hearing. Anion exchangers are one of the transporters responsible for the maintenance of homeostasis, but their expression profile in the primate cochlea has not been fully characterized. However, species-specific overlapping expression patterns and functional compensation in other organs, such as the kidney, pancreas and small intestine, have been reported. Here, we determined the expression patterns of the anion exchangers SLC26A4, SLC26A5, SLC26A6, SLC26A7, SLC26A11, SLC4A2 and SLC4A3 in the cochlea of a non-human primate, the common marmoset (Callithrix jacchus). Although the pattern of expression of SLC26A4 and SLC26A5 was similar to that in rodents, SLC26A7, SLC4A2, SLC4A3 exhibited different distributions. Notably, five transporters, SLC26A4, SLC26A6, SLC26A11 SLC4A2 and SLC4A3, were expressed in the cells of the outer sulcus. Our results reveal a species-specific distribution pattern of anion exchangers in the cochlea, particularly in the outer sulcus cells, suggesting functional compensation among these exchangers. This "primate-specific" pattern may be related to the human-specific hearing loss phenotypes of channelopathy disorders, including the SLC26A4-related diseases Pendred syndrome/DFNB4.
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Affiliation(s)
- Makoto Hosoya
- Keio University School of Medicine, Department of Otorhinolaryngology, Head and Neck Surgery, 35 Shinanomachi, Shinjuku-ku 160-8582, Japan
| | - Masato Fujioka
- Keio University School of Medicine, Department of Otorhinolaryngology, Head and Neck Surgery, 35 Shinanomachi, Shinjuku-ku 160-8582, Japan.
| | - Reona Kobayashi
- Keio University School of Medicine, Department of Physiology, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Hideyuki Okano
- Keio University School of Medicine, Department of Physiology, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Kaoru Ogawa
- Keio University School of Medicine, Department of Otorhinolaryngology, Head and Neck Surgery, 35 Shinanomachi, Shinjuku-ku 160-8582, Japan
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Haggie PM, Phuan PW, Tan JA, Zlock L, Finkbeiner WE, Verkman AS. Inhibitors of pendrin anion exchange identified in a small molecule screen increase airway surface liquid volume in cystic fibrosis. FASEB J 2016; 30:2187-97. [PMID: 26932931 DOI: 10.1096/fj.201600223r] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 02/06/2016] [Indexed: 12/31/2022]
Abstract
Pendrin (SLC26A4) is a Cl(-)/anion exchanger expressed in the epithelium of inflamed airways where it is thought to facilitate Cl(-) absorption and HCO3 (-) secretion. Studies using pendrin knockout mice and airway epithelial cells from hearing-impaired subjects with pendrin loss of function suggest involvement of pendrin in inflammatory lung diseases, including cystic fibrosis (CF), perhaps by regulation of airway surface liquid (ASL) volume. Here we identified small-molecule pendrin inhibitors and demonstrated their efficacy in increasing ASL volume. A cell-based, functional high-throughput screen of ∼36,000 synthetic small molecules produced 3 chemical classes of inhibitors of human pendrin. After structure-activity studies, tetrahydropyrazolopyridine and pyrazolothiophenesulfonamide compounds reversibly inhibited pendrin-facilitated Cl(-) exchange with SCN(-), I(-), NO3 (-), and HCO3 (-) with drug concentration causing 50% inhibition down to ∼2.5 μM. In well-differentiated primary cultures of human airway epithelial cells from non-CF and CF subjects, treatment with IL-13, which causes inflammation with strong pendrin up-regulation, strongly increased Cl(-)/HCO3 (-) exchange and the increase was blocked by pendrin inhibition. Pendrin inhibition significantly increased ASL depth (by ∼8 μm) in IL-13-treated non-CF and CF cells but not in untreated cells. These studies implicate the involvement of pendrin-facilitated Cl(-)/HCO3 (-) in the regulation of ASL volume and suggest the utility of pendrin inhibitors in inflammatory lung diseases, including CF.-Haggie, P. M., Phuan, P.-W., Tan, J.-A., Zlock, L., Finkbeiner, W. E., Verkman, A. S. Inhibitors of pendrin anion exchange identified in a small molecule screen increase airway surface liquid volume in cystic fibrosis.
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Affiliation(s)
- Peter M Haggie
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA; Department of Physiology, University of California, San Francisco, San Francisco, California, USA; and
| | - Puay-Wah Phuan
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA; Department of Physiology, University of California, San Francisco, San Francisco, California, USA; and
| | - Joseph-Anthony Tan
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA; Department of Physiology, University of California, San Francisco, San Francisco, California, USA; and
| | - Lorna Zlock
- Department of Pathology, University of California, San Francisco, San Francisco, California, USA
| | - Walter E Finkbeiner
- Department of Pathology, University of California, San Francisco, San Francisco, California, USA
| | - A S Verkman
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA; Department of Physiology, University of California, San Francisco, San Francisco, California, USA; and
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van Nierop J, Huinck W, Pennings R, Admiraal R, Mylanus E, Kunst H. Patients with Pendred syndrome: is cochlear implantation beneficial? Clin Otolaryngol 2016; 41:386-94. [DOI: 10.1111/coa.12532] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2015] [Indexed: 11/28/2022]
Affiliation(s)
- J.W.I. van Nierop
- Department of Otorhinolaryngology; Head and Neck Surgery; Radboud university medical center; Nijmegen The Netherlands
- Radboud Institute for Health Sciences; Radboud university medical center; Nijmegen The Netherlands
| | - W.J. Huinck
- Department of Otorhinolaryngology; Head and Neck Surgery; Radboud university medical center; Nijmegen The Netherlands
- Donders Institute for Brain; Cognition and Behaviour; Radboud university medical center; Nijmegen The Netherlands
| | - R.J.E. Pennings
- Department of Otorhinolaryngology; Head and Neck Surgery; Radboud university medical center; Nijmegen The Netherlands
- Radboud Institute for Health Sciences; Radboud university medical center; Nijmegen The Netherlands
| | - R.J.C. Admiraal
- Department of Otorhinolaryngology; Head and Neck Surgery; Radboud university medical center; Nijmegen The Netherlands
- Radboud Institute for Health Sciences; Radboud university medical center; Nijmegen The Netherlands
| | - E.A.M. Mylanus
- Department of Otorhinolaryngology; Head and Neck Surgery; Radboud university medical center; Nijmegen The Netherlands
- Donders Institute for Brain; Cognition and Behaviour; Radboud university medical center; Nijmegen The Netherlands
| | - H.P.M. Kunst
- Department of Otorhinolaryngology; Head and Neck Surgery; Radboud university medical center; Nijmegen The Netherlands
- Radboud Institute for Health Sciences; Radboud university medical center; Nijmegen The Netherlands
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Pang X, Chai Y, Chen P, He L, Wang X, Wu H, Yang T. Mono-allelic mutations of SLC26A4 is over-presented in deaf patients with non-syndromic enlarged vestibular aqueduct. Int J Pediatr Otorhinolaryngol 2015; 79:1351-3. [PMID: 26100058 DOI: 10.1016/j.ijporl.2015.06.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 06/03/2015] [Accepted: 06/04/2015] [Indexed: 11/17/2022]
Abstract
OBJECTIVES Recessive mutations of SLC26A4 are the major cause of hearing impairment associated with enlarged vestibular aqueduct (EVA). In a significant percentage of non-syndromic EVA patients, however, only mono-allelic mutations of SLC26A4 can be identified. In this study, we aimed to evaluate whether presence of mono-allelic mutations of SLC26A4 in those patients was coincidental or etiologically associated with the disorder. METHODS The exons and flanking splicing sites of SLC26A4 were sequenced in 150 Chinese Han deaf probands with non-syndromic EVA. c.919-2A >G and p.H723R, two frequent mutations of SLC26A4 in Chinese Hans, were screened by an allele-specific PCR-based array in 3056 ethnically-matched normal hearing controls. The frequency of mono-allelic c.919-2A >G and p.H723R mutations was determined in each group. The statistical significance of the difference was analyzed by Fisher's exact test. RESULTS Bi-allelic, mono-allelic and no mutation of SLC26A4 were detected in 98 (65.3%), 18 (12%) and 34 (22.67%) deaf probands with non-syndromic EVA, respectively. The frequency of mono-allelic c.919-2A >G and p.H723R mutations were significantly higher in the 150 deaf probands with non-syndromic EVA (8.67%) than in the 3056 normal hearing controls (1.4%, P=1.8×10(-6)). CONCLUSION Presence of mono-allelic mutations of SLC26A4 in non-syndromic EVA patients is etiologically associated with this disorder. Additional genetic or environmental causes may be present in those patients and demand further investigation and consideration during the genetic diagnosis and counseling.
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Affiliation(s)
- Xiuhong Pang
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China; Department of Otorhinolaryngology-Head and Neck Surgery, Taizhou People's Hospital, Jiangsu Province, China
| | - Yongchuan Chai
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Penghui Chen
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Longxia He
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Xiaowen Wang
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Tao Yang
- Department of Otolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
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Yao J, Qian X, Bao J, Wei Q, Lu Y, Zheng H, Cao X, Xing G. Probing the Effect of Two Heterozygous Mutations in Codon 723 of SLC26A4 on Deafness Phenotype Based on Molecular Dynamics Simulations. Sci Rep 2015; 5:10831. [PMID: 26035154 PMCID: PMC4451684 DOI: 10.1038/srep10831] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/27/2015] [Indexed: 11/09/2022] Open
Abstract
A Chinese family was identified with clinical features of enlarged vestibular aqueduct syndrome (EVAS). The mutational analysis showed that the proband (III-2) had EVAS with bilateral sensorineural hearing loss and carried a rare compound heterozygous mutation of SLC26A4 (IVS7-2A>G, c.2167C>G), which was inherited from the same mutant alleles of IVS7-2A>G heterozygous father and c.2167C>G heterozygous mother. Compared with another confirmed pathogenic biallelic mutation in SLC26A4 (IVS7-2A>G, c.2168A>G), these two biallelic mutations shared one common mutant allele and the same codon of the other mutant allele, but led to different changes of amino acid (p.H723D, p.H723R) and both resulted in the deafness phenotype. Structure-modeling indicated that these two mutant alleles changed the shape of pendrin protein encoded by SLC26A4 with increasing randomness in conformation, and might impair pendrin’s ability as an anion transporter. The molecular dynamics simulations also revealed that the stability of mutant pendrins was reduced with increased flexibility of backbone atoms, which was consistent with the structure-modeling results. These evidences indicated that codon 723 was a hot-spot region in SLC26A4 with a significant impact on the structure and function of pendrin, and acted as one of the genetic factors responsible for the development of hearing loss.
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Affiliation(s)
- Jun Yao
- Department of Biotechnology, School of Basic Medical Science, Nanjing Medical University, Nanjing, P.R. China
| | - Xuli Qian
- Department of Biotechnology, School of Basic Medical Science, Nanjing Medical University, Nanjing, P.R. China
| | - Jingxiao Bao
- School of Life Science and Technology, China Pharmaceutical University, Nanjing, P.R. China
| | - Qinjun Wei
- Department of Biotechnology, School of Basic Medical Science, Nanjing Medical University, Nanjing, P.R. China
| | - Yajie Lu
- Department of Biotechnology, School of Basic Medical Science, Nanjing Medical University, Nanjing, P.R. China
| | - Heng Zheng
- School of Life Science and Technology, China Pharmaceutical University, Nanjing, P.R. China
| | - Xin Cao
- Department of Biotechnology, School of Basic Medical Science, Nanjing Medical University, Nanjing, P.R. China
| | - Guangqian Xing
- Department of Otolaryngology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, P.R. 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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Stawicki TM, Esterberg R, Hailey DW, Raible DW, Rubel EW. Using the zebrafish lateral line to uncover novel mechanisms of action and prevention in drug-induced hair cell death. Front Cell Neurosci 2015; 9:46. [PMID: 25741241 PMCID: PMC4332341 DOI: 10.3389/fncel.2015.00046] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 01/30/2015] [Indexed: 01/01/2023] Open
Abstract
The majority of hearing loss and balance disorders are caused by the permanent loss of mechanosensory hair cells of the inner ear. Identification of genes and compounds that modulate susceptibility to hair cell death is frequently confounded by the difficulties of assaying for such complex phenomena in mammalian models. The zebrafish has emerged as a powerful animal model for genetic and chemical screening in many contexts. Several characteristics of the zebrafish, such as its small size and external location of mechanosensory hair cells within the lateral line sensory organ, uniquely position it as an ideal model organism for the study of hair cell toxicity. We have used this model to screen for genes and compounds that affect hair cell survival during ototoxin exposure and have identified agents that would not be expected to play a role in this process based on a priori knowledge of their function. The identification of such agents yields better understanding of hair cell death and holds promise to stem hearing loss and balance disorders in the human population.
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Affiliation(s)
- Tamara M Stawicki
- Virginia Merrill Bloedel Hearing Research Center, University of Washington Seattle, WA, USA ; Department of Biological Structure, University of Washington Seattle, WA, USA
| | - Robert Esterberg
- Virginia Merrill Bloedel Hearing Research Center, University of Washington Seattle, WA, USA ; Department of Otolaryngology, Head and Neck Surgery, University of Washington Seattle, WA, USA
| | - Dale W Hailey
- Virginia Merrill Bloedel Hearing Research Center, University of Washington Seattle, WA, USA ; Department of Biological Structure, University of Washington Seattle, WA, USA
| | - David W Raible
- Virginia Merrill Bloedel Hearing Research Center, University of Washington Seattle, WA, USA ; Department of Biological Structure, University of Washington Seattle, WA, USA
| | - Edwin W Rubel
- Virginia Merrill Bloedel Hearing Research Center, University of Washington Seattle, WA, USA ; Department of Otolaryngology, Head and Neck Surgery, University of Washington Seattle, WA, USA
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Abstract
Thyroid follicular epithelial cells produce thyroxine (T4) and its physiologically active derivative, 3,3',5-triiodothyronine (T3), hormones that regulate critical developmental and metabolic functions. In order for the thyroid to form hormone precursor, iodide, the defining element in thyroid hormone, must cross both blood-facing and luminal sides of the follicular epithelium. The pathway for uptake from blood is well understood, but the mechanism(s) that enable iodide to cross the luminally facing apical membrane remain obscure. This chapter considers the physiological properties of several molecularly characterized anion transport proteins, all of which potentially contribute to the overall mechanism of apical iodide efflux.
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Affiliation(s)
- Peying Fong
- Department of Anatomy and Physiology, Kansas State University College of Veterinary Medicine, Manhattan, Kansas, USA.
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Roy A, Al-bataineh MM, Pastor-Soler NM. Collecting duct intercalated cell function and regulation. Clin J Am Soc Nephrol 2015; 10:305-24. [PMID: 25632105 DOI: 10.2215/cjn.08880914] [Citation(s) in RCA: 154] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Intercalated cells are kidney tubule epithelial cells with important roles in the regulation of acid-base homeostasis. However, in recent years the understanding of the function of the intercalated cell has become greatly enhanced and has shaped a new model for how the distal segments of the kidney tubule integrate salt and water reabsorption, potassium homeostasis, and acid-base status. These cells appear in the late distal convoluted tubule or in the connecting segment, depending on the species. They are most abundant in the collecting duct, where they can be detected all the way from the cortex to the initial part of the inner medulla. Intercalated cells are interspersed among the more numerous segment-specific principal cells. There are three types of intercalated cells, each having distinct structures and expressing different ensembles of transport proteins that translate into very different functions in the processing of the urine. This review includes recent findings on how intercalated cells regulate their intracellular milieu and contribute to acid-base regulation and sodium, chloride, and potassium homeostasis, thus highlighting their potential role as targets for the treatment of hypertension. Their novel regulation by paracrine signals in the collecting duct is also discussed. Finally, this article addresses their role as part of the innate immune system of the kidney tubule.
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Affiliation(s)
- Ankita Roy
- Renal-Electrolyte Division, Department of Medicine; and
| | | | - Núria M Pastor-Soler
- Renal-Electrolyte Division, Department of Medicine; and Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania A.R. and M.M.A. contributed equally to this work.
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Yamazaki H, Naito Y, Moroto S, Tamaya R, Yamazaki T, Fujiwara K, Ito J. SLC26A4 p.Thr410Met homozygous mutation in a patient with a cystic cochlea and an enlarged vestibular aqueduct showing characteristic features of incomplete partition type I and II. Int J Pediatr Otorhinolaryngol 2014; 78:2322-6. [PMID: 25468468 DOI: 10.1016/j.ijporl.2014.10.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 10/21/2014] [Accepted: 10/29/2014] [Indexed: 11/16/2022]
Abstract
Mutations of SLC26A4 are associated with incomplete partition type II (IP-II) and isolated enlargement of the vestibular aqueduct (EVA). We experienced a congenitally deaf 6-year-old boy with a rare p.Thr410Met homozygous mutation in SLC26A4 who underwent bilateral cochlear implantation. He had bilateral inner ear malformation, in which the dilated vestibule and EVA were identical to those in IP-II, but the cochlea lacking a bony modiolus resembled that in incomplete partition type I. These results suggest that homozygous mutations in SLC26A4 are always associated with EVA, while the severity of cochlear malformation may vary depending on the type of SLC26A4 mutation.
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Affiliation(s)
- Hiroshi Yamazaki
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
| | - Yasushi Naito
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Saburo Moroto
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Rinko Tamaya
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Tomoko Yamazaki
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Keizo Fujiwara
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Juichi Ito
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Lundberg YW, Xu Y, Thiessen KD, Kramer KL. Mechanisms of otoconia and otolith development. Dev Dyn 2014; 244:239-53. [PMID: 25255879 DOI: 10.1002/dvdy.24195] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Otoconia are bio-crystals that couple mechanic forces to the sensory hair cells in the utricle and saccule, a process essential for us to sense linear acceleration and gravity for the purpose of maintaining bodily balance. In fish, structurally similar bio-crystals called otoliths mediate both balance and hearing. Otoconia abnormalities are common and can cause vertigo and imbalance in humans. However, the molecular etiology of these illnesses is unknown, as investigators have only begun to identify genes important for otoconia formation in recent years. RESULTS To date, in-depth studies of selected mouse otoconial proteins have been performed, and about 75 zebrafish genes have been identified to be important for otolith development. CONCLUSIONS This review will summarize recent findings as well as compare otoconia and otolith development. It will provide an updated brief review of otoconial proteins along with an overview of the cells and cellular processes involved. While continued efforts are needed to thoroughly understand the molecular mechanisms underlying otoconia and otolith development, it is clear that the process involves a series of temporally and spatially specific events that are tightly coordinated by numerous proteins. Such knowledge will serve as the foundation to uncover the molecular causes of human otoconia-related disorders.
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Affiliation(s)
- Yunxia Wang Lundberg
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, Nebraska
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62
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Lundberg YW, Xu Y, Thiessen KD, Kramer KL. Mechanisms of otoconia and otolith development. Dev Dyn 2014. [PMID: 25255879 DOI: 10.1002/dvdy.24195(2014)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Otoconia are bio-crystals that couple mechanic forces to the sensory hair cells in the utricle and saccule, a process essential for us to sense linear acceleration and gravity for the purpose of maintaining bodily balance. In fish, structurally similar bio-crystals called otoliths mediate both balance and hearing. Otoconia abnormalities are common and can cause vertigo and imbalance in humans. However, the molecular etiology of these illnesses is unknown, as investigators have only begun to identify genes important for otoconia formation in recent years. RESULTS To date, in-depth studies of selected mouse otoconial proteins have been performed, and about 75 zebrafish genes have been identified to be important for otolith development. CONCLUSIONS This review will summarize recent findings as well as compare otoconia and otolith development. It will provide an updated brief review of otoconial proteins along with an overview of the cells and cellular processes involved. While continued efforts are needed to thoroughly understand the molecular mechanisms underlying otoconia and otolith development, it is clear that the process involves a series of temporally and spatially specific events that are tightly coordinated by numerous proteins. Such knowledge will serve as the foundation to uncover the molecular causes of human otoconia-related disorders.
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Affiliation(s)
- Yunxia Wang Lundberg
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, Nebraska
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Pique LM, Brennan ML, Davidson CJ, Schaefer F, Greinwald J, Schrijver I. Mutation analysis of the SLC26A4, FOXI1 and KCNJ10 genes in individuals with congenital hearing loss. PeerJ 2014; 2:e384. [PMID: 24860705 PMCID: PMC4017815 DOI: 10.7717/peerj.384] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 04/25/2014] [Indexed: 01/05/2023] Open
Abstract
Pendred syndrome (PDS) and DFNB4 comprise a phenotypic spectrum of sensorineural hearing loss disorders that typically result from biallelic mutations of the SLC26A4 gene. Although PDS and DFNB4 are recessively inherited, sequencing of the coding regions and splice sites of SLC26A4 in individuals suspected to be affected with these conditions often fails to identify two mutations. We investigated the potential contribution of large SLC26A4 deletions and duplications to sensorineural hearing loss (SNHL) by screening 107 probands with one known SLC26A4 mutation by Multiplex Ligation-dependent Probe Amplification (MLPA). A heterozygous deletion, spanning exons 4-6, was detected in only one individual, accounting for approximately 1% of the missing mutations in our cohort. This low frequency is consistent with previously published MLPA results. We also examined the potential involvement of digenic inheritance in PDS/DFNB4 by sequencing the coding regions of FOXI1 and KCNJ10. Of the 29 probands who were sequenced, three carried nonsynonymous variants including one novel sequence change in FOXI1 and two polymorphisms in KCNJ10. We performed a review of prior studies and, in conjunction with our current data, conclude that the frequency of FOXI1 (1.4%) and KCNJ10 (3.6%) variants in PDS/DFNB4 individuals is low. Our results, in combination with previously published reports, indicate that large SLC26A4 deletions and duplications as well as mutations of FOXI1 and KCNJ10 play limited roles in the pathogenesis of SNHL and suggest that other genetic factors likely contribute to the phenotype.
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Affiliation(s)
- Lynn M Pique
- Department of Pathology, Stanford University Medical Center , Stanford, CA , USA
| | - Marie-Luise Brennan
- Department of Pediatrics, Stanford University Medical Center , Stanford, CA , USA
| | | | - Frederick Schaefer
- Molecular Genetics, Center for Genetic Testing at Saint Francis Hospital , Tulsa, OK , USA
| | - John Greinwald
- Divisions of Human Genetics and Otolaryngology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA
| | - Iris Schrijver
- Department of Pathology, Stanford University Medical Center , Stanford, CA , USA ; Department of Pediatrics, Stanford University Medical Center , Stanford, CA , USA
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JIANG HUA, CHEN JIA, SHAN XINJI, LI YING, HE JIANGUO, YANG BEIBEI. Prevalence and range of GJB2 and SLC26A4 mutations in patients with autosomal recessive non-syndromic hearing loss. Mol Med Rep 2014; 10:379-86. [DOI: 10.3892/mmr.2014.2148] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 03/13/2014] [Indexed: 11/05/2022] Open
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Bohnenpoll T, Trowe MO, Wojahn I, Taketo MM, Petry M, Kispert A. Canonical Wnt signaling regulates the proliferative expansion and differentiation of fibrocytes in the murine inner ear. Dev Biol 2014; 391:54-65. [PMID: 24727668 DOI: 10.1016/j.ydbio.2014.03.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 03/27/2014] [Accepted: 03/29/2014] [Indexed: 01/18/2023]
Abstract
Otic fibrocytes tether the cochlear duct to the surrounding otic capsule but are also critically involved in maintenance of ion homeostasis in the cochlea, thus, perception of sound. The molecular pathways that regulate the development of this heterogenous group of cells from mesenchymal precursors are poorly understood. Here, we identified epithelial Wnt7a and Wnt7b as possible ligands of Fzd-mediated β-catenin (Ctnnb1)-dependent (canonical) Wnt signaling in the adjacent undifferentiated periotic mesenchyme (POM). Mice with a conditional deletion of Ctnnb1 in the POM exhibited a complete failure of fibrocyte differentiation, a severe reduction of mesenchymal cells surrounding the cochlear duct, loss of pericochlear spaces, a thickening and partial loss of the bony capsule and a secondary disturbance of cochlear duct coiling shortly before birth. Analysis at earlier stages revealed that radial patterning of the POM in two domains with highly condensed cartilaginous precursors and more loosely arranged inner mesenchymal cells occurred normally but that proliferation in the inner domain was reduced and cytodifferentiation failed. Cells with mis/overexpression of a stabilized form of Ctnnb1 in the entire POM mesenchyme sorted to the inner mesenchymal compartment and exhibited increased proliferation. Our analysis suggests that Wnt signals from the cochlear duct epithelium are crucial to induce differentiation and expansion of fibrocyte precursor cells. Our findings emphasize the importance of epithelial-mesenchymal signaling in inner ear development.
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Affiliation(s)
- Tobias Bohnenpoll
- Institut für Molekularbiologie, OE5250, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - Mark-Oliver Trowe
- Institut für Molekularbiologie, OE5250, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - Irina Wojahn
- Institut für Molekularbiologie, OE5250, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | | | - Marianne Petry
- Institut für Molekularbiologie, OE5250, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - Andreas Kispert
- Institut für Molekularbiologie, OE5250, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
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Ladsous M, Vlaeminck-Guillem V, Dumur V, Vincent C, Dubrulle F, Dhaenens CM, Wémeau JL. Analysis of the thyroid phenotype in 42 patients with Pendred syndrome and nonsyndromic enlargement of the vestibular aqueduct. Thyroid 2014; 24:639-48. [PMID: 24224479 DOI: 10.1089/thy.2013.0164] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Pendred syndrome (PS), a recessive disorder caused by mutations in the SLC26A4 (PDS) gene, is associated with deafness and goiter. SLC26A4 mutations have also been identified in patients exhibiting isolated sensorineural hearing loss without apparent thyroid abnormality (nonsyndromic enlargement of the vestibular aqueduct; nonsyndromic EVA). Our aim was to describe systematically the thyroidal phenotypes and the SLC26A4 genotypes of patients presenting with PS or nonsyndromic EVA. METHODS Nineteen patients with PS and 23 patients with nonsyndromic EVA, aged 5-53 years, were included. They underwent thyroid evaluation (physical examination, biological thyroid function tests, measurement of thyroglobulin level, thyroid ultrasonography, and thyroid (123)I scintigraphy with perchlorate discharge test), otological evaluation, and SLC26A4 mutation screening. RESULTS In 19 patients with PS, goiter was identified in 15 (79%) and hypothyroidism in 15 (79%); hypothyroidism was subclinical in four patients and congenital in six patients. The perchlorate discharge test (PDT) was positive in 10/16 (63%). Morphological evaluation of the inner ear using MRI and/or CT showed bilateral EVA in 15/15 PS patients. Mutation screening revealed two SLC26A4 mutant alleles in all 19 PS patients that were homozygous in two families and compound heterozygous in 12 families. In the 23 patients with nonsyndromic EVA, systematic thyroid evaluation found no abnormalities except for slightly increased thyroglobulin levels in two patients. SLC26A4 mutations were identified in 9/23 (39%). Mutations were biallelic in two (compound heterozygous) and monoallelic in seven patients. CONCLUSION The thyroid phenotype is widely variable in PS. SLC26A4 mutation screening is needed in patients exhibiting PS or nonsyndromic EVA. PS is associated with biallelic SLC26A4 mutations and nonsyndromic EVA with no, monoallelic, or biallelic SLC26A4 mutations. Systematic thyroid evaluation is recommended in patients with nonsyndromic EVA associated with one or two SLC26A4 mutations. We propose using a combination of three parameters to define and diagnose PS: (i) sensorineural deafness with bilateral EVA; (ii) thyroid abnormality comprising goiter and/or hypothyroidism and/or a positive PDT; (iii) biallelic SLC26A4 mutations.
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Affiliation(s)
- Miriam Ladsous
- 1 Department of Endocrinology, Regional University Hospital Center (CHRU) of Lille, Lille, France
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Kühnen P, Turan S, Fröhler S, Güran T, Abali S, Biebermann H, Bereket A, Grüters A, Chen W, Krude H. Identification of PENDRIN (SLC26A4) mutations in patients with congenital hypothyroidism and "apparent" thyroid dysgenesis. J Clin Endocrinol Metab 2014; 99:E169-76. [PMID: 24248179 DOI: 10.1210/jc.2013-2619] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Congenital hypothyroidism, the most frequent endocrine congenital disease, can occur either based on a thyroid hormone biosynthesis defect or can predominantly be due to thyroid dysgenesis. However, a genetic cause could so far only be identified in less than 10% of patients with a thyroid dysgenesis. OBJECTIVES Exome sequencing was used for the first time to find additional genetic defects in thyroid dysgenesis. PATIENTS AND METHODS In a consanguineous family with thyroid dysgenesis, exome sequencing was applied, and findings were further validated by Sanger sequencing in a cohort of 94 patients with thyroid dysgenesis. RESULTS By exome sequencing we identified a homozygous missense mutation (p.Leu597Ser) in the SLC26A4 gene of a patient with hypoplastic thyroid tissue, who was otherwise healthy. In the cohort of patients with thyroid dysgenesis, we observed a second case with a homozygous missense mutation (p.Gln413Arg) in the SLC26A4 gene, who was additionally affected by severe hearing problems. Both mutations were previously described as loss-of-function mutations in patients with Pendred syndrome and nonsyndromic enlarged vestibular aqueduct. CONCLUSION We unexpectedly identified SLC26A4 mutations that were hitherto diagnosed in thyroid dyshormonogenesis patients, now for the first time in patients with structural thyroid defects. This result resembles the historic description of thyroid atrophy in patients with the so-called myxedematous form of cretinism after severe iodine deficiency. Most likely the thyroid defect of the two homozygous SLC26A4 gene mutation carriers represents a kind of secondary thyroid atrophy, rather than a primary defect of thyroid development in the sense of thyroid agenesis. Our study extends the variable clinical spectrum of patients with SLC26A4 mutations and points out the necessity to analyze the SLC26A4 gene in patients with apparent thyroid dysgenesis in addition to the known candidate genes TSHR, PAX8, NKX2.1, NKX2.5, and FOXE1.
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Affiliation(s)
- Peter Kühnen
- Institute of Experimental Pediatric Endocrinology (P.K., H.B., A.G., H.K.), Charité Universitätsmedizin Berlin, 13353 Berlin, Germany; Department of Pediatric Endocrinology and Diabetes (S.T., T.G., S.A., A.B.), Marmara University Hospital, 34722 Istanbul, Turkey; and Max-Delbrück Center for Molecular Medicine (S.F., W.C.), 13092 Berlin-Buch, Germany
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Xin F, Yuan Y, Deng X, Han M, Wang G, Zhao J, Gao X, Liu J, Yu F, Han D, Dai P. Genetic mutations in nonsyndromic deafness patients of Chinese minority and Han ethnicities in Yunnan, China. J Transl Med 2013; 11:312. [PMID: 24341454 PMCID: PMC3878508 DOI: 10.1186/1479-5876-11-312] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/11/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Each year in China, 30,000 babies are born with congenital hearing impairment. However, the molecular etiology of hearing impairment in the Yunnan Province population where more than 52 minorities live has not been thoroughly investigated. To provide appropriate genetic testing and counseling to these families, we investigated the molecular etiology of nonsyndromic deafness in this population. METHODS Unrelated students with hearing loss (n = 235) who attended Kunming Huaxia secondary specialized school in Yunnan enrolled in this study. Three prominent deafness-related genes, GJB2, SLC26A4 and mtDNA 12S rRNA, were analyzed. High-resolution temporal bone computed tomography (CT) scan examinations were performed in 100 cases, including 16 cases with SLC26A4 gene variants, and 37 minorities and 47 Han cases without any SLC26A4 gene mutation. RESULTS The GJB2 mutation was detected in 16.67% (7/42) of minority patients and 17.62% (34/193) of Chinese Han patients (P > 0.05). 235delC was the hotspot mutation in nonsyndromic hearing loss (NSHL) patients, whereas 35delG was not found. The 431_450del19 mutation was detected for the first time in Han NSHL patients, which resulted in a premature stop codon and changed the protein. The SLC26A4 mutation was found in 9.52% (4/42) of minority patients and 9.84% (19/193) of Han Chinese patients (P > 0.05). The frequencies of mtDNA 12S rRNA mutation in minority and Han Chinese patients were 11.90% (5/42) and 7.77% (15/193; P > 0.05), respectively. Sixteen (16/23, 69.57%) patients with SLC26A4 mutations received temporal bone CT scan, and 14 patients were diagnosed with enlarged vestibular aqueducts (EVAs); the other 2 patients had normal inner ear development. The ratio of EVA in the minorities was 14.63% (6/41). CONCLUSIONS In this study, a total of 35.74% deaf patients showed evidence of genetic involvement, based on either genetic screening or family history; 17.45%, 9.79%, and 8.51% of the patients were determined to have inherited hearing impairment caused by GJB2, SLC26A4, and mtDNA 1555A > G mutations. There was no significant difference in deafness associated gene mutational spectrum and frequency between the Yunnan minority and Han patients.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Pu Dai
- Department of Otolaryngology and Genetic Testing Center for Deafness, Chinese PLA General Hospital, Beijing 100853, P,R, China.
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Chan HC, Sun X. SLC26 anion exchangers in uterine epithelial cells and spermatozoa: clues from the past and hints to the future. Cell Biol Int 2013; 38:1-7. [PMID: 24115633 DOI: 10.1002/cbin.10183] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 08/15/2013] [Indexed: 12/27/2022]
Abstract
The solute carrier 26 (SLC26) family emerges as a distinct class of anion transporters with its members SLC26A3 (Slc26a3) and SLC26A6 (Slc26a6) reported to be electrogenic Cl(-)/HCO3(-) exchangers. While it is known that uterine fluid has high HCO3(-) content and that HCO3(-) is essential for sperm capacitation, the molecular mechanisms underlying the transport of HCO3(-) across uterine epithelial cells and sperm have not been fully investigated. The present review re-examines the results from early reports studying anion transport, finding clues for the involvement of Cl(-)/HCO3(-) anion exchangers in electrogenic HCO3(-) transport across endometrial epithelium. We also summarise recent work on Slc26a3 and Slc26a6 in uterine epithelial cells and sperm, revealing their functional role in working closely with the cystic fibrosis transmembrane conductance regulator (CFTR) for HCO3(-) transport in these cells. The possible involvement of these anion exchangers in other HCO3(-) dependent reproductive processes and their implications for infertility are also discussed.
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Affiliation(s)
- Hsiao Chang Chan
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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Jagger DJ, Forge A. The enigmatic root cell – Emerging roles contributing to fluid homeostasis within the cochlear outer sulcus. Hear Res 2013; 303:1-11. [DOI: 10.1016/j.heares.2012.10.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/19/2012] [Accepted: 10/26/2012] [Indexed: 12/20/2022]
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Li X, Sanneman JD, Harbidge DG, Zhou F, Ito T, Nelson R, Picard N, Chambrey R, Eladari D, Miesner T, Griffith AJ, Marcus DC, Wangemann P. SLC26A4 targeted to the endolymphatic sac rescues hearing and balance in Slc26a4 mutant mice. PLoS Genet 2013; 9:e1003641. [PMID: 23874234 PMCID: PMC3708829 DOI: 10.1371/journal.pgen.1003641] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 06/01/2013] [Indexed: 12/13/2022] Open
Abstract
Mutations of SLC26A4 are a common cause of human hearing loss associated with enlargement of the vestibular aqueduct. SLC26A4 encodes pendrin, an anion exchanger expressed in a variety of epithelial cells in the cochlea, the vestibular labyrinth and the endolymphatic sac. Slc26a4 (Δ/Δ) mice are devoid of pendrin and develop a severe enlargement of the membranous labyrinth, fail to acquire hearing and balance, and thereby provide a model for the human phenotype. Here, we generated a transgenic mouse line that expresses human SLC26A4 controlled by the promoter of ATP6V1B1. Crossing this transgene into the Slc26a4 (Δ/Δ) line restored protein expression of pendrin in the endolymphatic sac without inducing detectable expression in the cochlea or the vestibular sensory organs. The transgene prevented abnormal enlargement of the membranous labyrinth, restored a normal endocochlear potential, normal pH gradients between endolymph and perilymph in the cochlea, normal otoconia formation in the vestibular labyrinth and normal sensory functions of hearing and balance. Our study demonstrates that restoration of pendrin to the endolymphatic sac is sufficient to restore normal inner ear function. This finding in conjunction with our previous report that pendrin expression is required for embryonic development but not for the maintenance of hearing opens the prospect that a spatially and temporally limited therapy will restore normal hearing in human patients carrying a variety of mutations of SLC26A4.
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Affiliation(s)
- Xiangming Li
- Anatomy & Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
| | - Joel D. Sanneman
- Anatomy & Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
| | - Donald G. Harbidge
- Anatomy & Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
| | - Fei Zhou
- Anatomy & Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
| | - Taku Ito
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland, United States of America
| | - Raoul Nelson
- Department of Pediatrics, Division of Nephrology, School of Medicine, University of Utah, Salt Lake City, Utah, United States of America
| | - Nicolas Picard
- Inserm, UMRS 970, Centre de recherche PARCC (Paris centre de recherche cardiovasculaire); Faculté de Médecine Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Régine Chambrey
- Inserm, UMRS 970, Centre de recherche PARCC (Paris centre de recherche cardiovasculaire); Faculté de Médecine Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Dominique Eladari
- Inserm, UMRS 970, Centre de recherche PARCC (Paris centre de recherche cardiovasculaire); Faculté de Médecine Paris Descartes, Sorbonne Paris Cité, Paris, France
- Département de Physiologie, HEGP, AP-HP, Paris, France
| | - Tracy Miesner
- Comparative Medicine Group, Kansas State University, Manhattan, Kansas, United States of America
| | - Andrew J. Griffith
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland, United States of America
| | - Daniel C. Marcus
- Anatomy & Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
| | - Philine Wangemann
- Anatomy & Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
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Lu YC, Wu CC, Yang TH, Lin YH, Yu IS, Lin SW, Chang Q, Lin X, Wong JM, Hsu CJ. Differences in the pathogenicity of the p.H723R mutation of the common deafness-associated SLC26A4 gene in humans and mice. PLoS One 2013; 8:e64906. [PMID: 23755160 PMCID: PMC3670936 DOI: 10.1371/journal.pone.0064906] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Accepted: 04/19/2013] [Indexed: 11/23/2022] Open
Abstract
Mutations in the SLC26A4 gene are a common cause of human hereditary hearing impairment worldwide. Previous studies have demonstrated that different SLC26A4 mutations have different pathogenetic mechanisms. By using a genotype-driven approach, we established a knock-in mouse model (i.e., Slc26a4tm2Dontuh/tm2Dontuh mice) homozygous for the common p.H723R mutation in the East Asian population. To verify the pathogenicity of the p.H723R allele in mice, we further generated mice with compound heterozygous mutations (i.e., Slc26a4tm1Dontuh/tm2Dontuh) by intercrossing Slc26a4+/tm2Dontuh mice with Slc26a4tm1Dontuh/tm1Dontuh mice, which segregated the c.919-2A>G mutation with an abolished Slc26a4 function. Mice were then subjected to audiologic assessments, a battery of vestibular evaluations, inner ear morphological studies, and noise exposure experiments. The results were unexpected; both Slc26a4tm2Dontuh/tm2Dontuh and Slc26a4tm1Dontuh/tm2Dontuh mice showed normal audiovestibular phenotypes and inner ear morphology, and they did not show significantly higher shifts in hearing thresholds after noise exposure than the wild-type mice. The results indicated not only the p.H723R allele was non-pathogenic in mice, but also a single p.H723R allele was sufficient to maintain normal inner ear physiology in heterozygous compound mice. There might be discrepancies in the pathogenicity of specific SLC26A4 mutations in humans and mice; therefore, precautions should be taken when extrapolating the results of animal studies to humans.
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Affiliation(s)
- Ying-Chang Lu
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Ting-Hua Yang
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Yin-Hung Lin
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - I-Shing Yu
- Transgenic Mouse Models Core (TMMC), Division of Genomic Medicine, Research Center For Medical Excellence, National Taiwan University, Taipei, Taiwan
| | - Shu-Wha Lin
- Transgenic Mouse Models Core (TMMC), Division of Genomic Medicine, Research Center For Medical Excellence, National Taiwan University, Taipei, Taiwan
| | - Qing Chang
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Jau-Min Wong
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Chuan-Jen Hsu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
- Department of Otolaryngology, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail:
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73
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Khan MR, Bashir R, Naz S. SLC26A4 mutations in patients with moderate to severe hearing loss. Biochem Genet 2013; 51:514-23. [PMID: 23504402 DOI: 10.1007/s10528-013-9582-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 11/15/2012] [Indexed: 11/28/2022]
Abstract
Mutations in SLC26A4 cause either syndromic or nonsyndromic hearing loss. We identified a link between hearing loss and DFNB4 in 3 of the 50 families participating in this study. Sequencing analysis revealed two SLC26A4 mutations, p.V239D and p.S57X, in affected members of the 3 families. These mutations have been previously reported in deaf individuals from the subcontinent, all of whom manifested profound deafness. The patients investigated in our study exhibited moderate to severe hearing loss. Our results show that inactivating SLC26A4 mutations that cause profound deafness can also be involved in the etiology of moderate to severe hearing loss. The type of mutation cannot predict the severity of the hearing loss in all cases, and there may be additional epistatic interactions that could modify the phenotype.
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Affiliation(s)
- Muhammad Riaz Khan
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
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Wu L, Sagong B, Choi JY, Kim UK, Bok J. A systematic survey of carbonic anhydrase mRNA expression during mammalian inner ear development. Dev Dyn 2013; 242:269-80. [PMID: 23233153 DOI: 10.1002/dvdy.23917] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 12/03/2012] [Accepted: 12/03/2012] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Carbonic anhydrases (CAs), which catalyze CO(2) hydration to bicarbonate and protons, have been suggested to regulate potassium homeostasis and endocochlear potential in the mammalian cochlea. Sixteen mammalian CA isozymes are currently known. To understand the specific roles of CA isozymes in the inner ear, a systematic survey was conducted to reveal temporal and spatial expression patterns of all 16 CA isozymes during inner ear development. RESULTS Our quantitative reverse transcriptase-polymerase chain reaction results showed that different tissues express unique combinations of CA isozymes. During inner ear development, transcripts of four cytosolic isozymes (Car1, Car2, Car3, and Car13), two membrane-bound isozymes (Car12 and Car14), and two CA-related proteins (Car8 and Car11) were expressed at higher levels than other isozymes. Spatial expression patterns of these isozymes within developing inner ears were determined by in situ hybridization. Each isozyme showed a unique expression pattern during development. For example, Car12 and Car13 expression closely overlapped with Pendrin, an anion exchanger, while Car2 overlapped with Na-K-ATPase in type II and IV otic fibrocytes, suggesting functional relationships in the inner ear. CONCLUSIONS The temporal and spatial expression patterns of each CA isozyme suggest unique and differential roles in inner ear development and function.
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Affiliation(s)
- Ling Wu
- Department of Anatomy, Yonsei University College of Medicine, Seoul, South Korea
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Yuan Y, Guo W, Tang J, Zhang G, Wang G, Han M, Zhang X, Yang S, He DZZ, Dai P. Molecular epidemiology and functional assessment of novel allelic variants of SLC26A4 in non-syndromic hearing loss patients with enlarged vestibular aqueduct in China. PLoS One 2012. [PMID: 23185506 PMCID: PMC3503781 DOI: 10.1371/journal.pone.0049984] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Background Mutations in SLC26A4, which encodes pendrin, are a common cause of deafness. SLC26A4 mutations are responsible for Pendred syndrome and non-syndromic enlarged vestibular aqueduct (EVA). The mutation spectrum of SLC26A4 varies widely among ethnic groups. To investigate the incidence of EVA in Chinese population and to provide appropriate genetic testing and counseling to patients with SLC26A4 variants, we conducted a large-scale molecular epidemiological survey of SLC26A4. Methods A total of 2352 unrelated non-syndromic hearing loss patients from 27 different regions of China were included. Hot spot regions of SLC26A4, exons 8, 10 and 19 were sequenced. For patients with one allelic variant in the hot spot regions, the other exons were sequenced one by one until two mutant alleles had been identified. Patients with SLC26A4 variants were then examined by temporal bone computed tomography scan for radiological diagnosis of EVA. Ten SLC26A4 variants were cloned for functional study. Confocal microscopy and radioisotope techniques were used to examine the membrane expression of pendrin and transporter function. Results Of the 86 types of variants found, 47 have never been reported. The ratio of EVA in the Chinese deaf population was at least 11%, and that in patients of Han ethnicity reached at least 13%. The mutational spectrum and mutation detection rate of SLC26A4 are distinct among both ethnicities and regions of Mainland China. Most of the variants caused retention of pendrin in the intracellular region. All the mutant pendrins showed significantly reduced transport capability. Conclusion An overall description of the molecular epidemiological findings of SLC26A4 in China is provided. The functional assessment procedure can be applied to identification of pathogenicity of variants. These findings are valuable for genetic diagnosis, genetic counseling, prenatal testing and pre-implantation diagnosis in EVA families.
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Affiliation(s)
- Yongyi Yuan
- Department of Otolaryngology, Chinese PLA General Hospital, Beijing, People’s Republic of China
- Department of Otolaryngology, Hainan Branch of Chinese PLA General Hospital, Sanya, People’s Republic of China
| | - Weiwei Guo
- Department of Otolaryngology, Chinese PLA General Hospital, Beijing, People’s Republic of China
| | - Jie Tang
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska, United States of America
| | - Guozheng Zhang
- Department of Otolaryngology, 3rd hospital of Hebei Medical University, Shijiazhuang, Hebei Province, People’s Republic of China
| | - Guojian Wang
- Department of Otolaryngology, Chinese PLA General Hospital, Beijing, People’s Republic of China
- Department of Otolaryngology, Hainan Branch of Chinese PLA General Hospital, Sanya, People’s Republic of China
| | - Mingyu Han
- Department of Otolaryngology, Chinese PLA General Hospital, Beijing, People’s Republic of China
- Department of Otolaryngology, Hainan Branch of Chinese PLA General Hospital, Sanya, People’s Republic of China
| | - Xun Zhang
- Department of Otolaryngology, 3rd hospital of Hebei Medical University, Shijiazhuang, Hebei Province, People’s Republic of China
| | - Shiming Yang
- Department of Otolaryngology, Chinese PLA General Hospital, Beijing, People’s Republic of China
- * E-mail: (PD); (SY); (DZZH)
| | - David Z. Z. He
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska, United States of America
- * E-mail: (PD); (SY); (DZZH)
| | - Pu Dai
- Department of Otolaryngology, Chinese PLA General Hospital, Beijing, People’s Republic of China
- Department of Otolaryngology, Hainan Branch of Chinese PLA General Hospital, Sanya, People’s Republic of China
- * E-mail: (PD); (SY); (DZZH)
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Li Q, Zhu QW, Yuan YY, Huang SS, Han DY, Huang DL, Dai P. Identification of SLC26A4 c.919-2A>G compound heterozygosity in hearing-impaired patients to improve genetic counseling. J Transl Med 2012; 10:225. [PMID: 23151025 PMCID: PMC3514144 DOI: 10.1186/1479-5876-10-225] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 11/12/2012] [Indexed: 11/18/2022] Open
Abstract
Background Mutations in the SLC26A4 gene, which encodes the anion transporter, pendrin, are a major cause of autosomal recessive non-syndromic hearing loss (NSHL) in some Asian populations. SLC26A4 c.919-2A>G (IVS7-2A>G) is the most common mutation in East Asian deaf populations. To provide a basis for improving the clinical diagnosis of deaf patients, we evaluated 80 patients with the SLC26A4 c.919-2A>G monoallelic mutation from 1065 hearing-impaired subjects and reported the occurrence of a second mutant allele in these patients. Methods The occurrence of a second mutant allele in these 80 patients with a single c.919-2A>G mutation was investigated. Mutation screening was performed by bidirectional sequencing in SLC26A4 exons 2 to 6 and 9 to 21. Results We found that 47/80 patients carried another SLC26A4 c.919-2A>G compound mutation. The five most common mutations were: p.H723R, p.T410M, 15+5G>A (c.1705+5G>A), p.L676Q and p.N392Y. We found a Chinese-specific SLC26A4 mutation spectrum and an associated SLC26A4 contribution to deafness. Conclusion Our study illustrates that mutation analysis of other SLC26A4 exons should be undertaken in deaf patients with a single heterozygous SLC26A4 mutation. Moreover, a model of compound heterozygosity may partially explain the disease phenotype.
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Affiliation(s)
- Qi Li
- Division of Pediatric Otolaryngology, Nanjing Children’s Hospital, Nanjing Medical University, Nanjing, Jiangsu 210008, China
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Lorente-Cánovas B, Ingham N, Norgett EE, Golder ZJ, Karet Frankl FE, Steel KP. Mice deficient in H+-ATPase a4 subunit have severe hearing impairment associated with enlarged endolymphatic compartments within the inner ear. Dis Model Mech 2012; 6:434-42. [PMID: 23065636 PMCID: PMC3597025 DOI: 10.1242/dmm.010645] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Mutations in the ATP6V0A4 gene lead to autosomal recessive distal renal tubular acidosis in patients, who often show sensorineural hearing impairment. A first Atp6v0a4 knockout mouse model that recapitulates the loss of H+-ATPase function seen in humans has been generated and recently reported (Norgett et al., 2012). Here, we present the first detailed analysis of the structure and function of the auditory system in Atp6v0a4−/− knockout mice. Measurements of the auditory brainstem response (ABR) showed significantly elevated thresholds in homozygous mutant mice, which indicate severe hearing impairment. Heterozygote thresholds were normal. Analysis of paint-filled inner ears and sections from E16.5 embryos revealed a marked expansion of cochlear and endolymphatic ducts in Atp6v0a4−/− mice. A regulatory link between Atp6v0a4, Foxi1 and Pds has been reported and we found that the endolymphatic sac of Atp6v0a4−/− mice expresses both Foxi1 and Pds, which suggests a downstream position of Atp6v0a4. These mutants also showed a lack of endocochlear potential, suggesting a functional defect of the stria vascularis on the lateral wall of the cochlear duct. However, the main K+ channels involved in the generation of endocochlear potential, Kcnj10 and Kcnq1, are strongly expressed in Atp6v0a4−/− mice. Our results lead to a better understanding of the role of this proton pump in hearing function.
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Hu X, Liang F, Zhao M, Gong A, Berry ER, Shi Y, Wang Y, Chen Y, Liu A, Qu C. Mutational analysis of the SLC26A4 gene in Chinese sporadic nonsyndromic hearing-impaired children. Int J Pediatr Otorhinolaryngol 2012; 76:1474-80. [PMID: 22796198 DOI: 10.1016/j.ijporl.2012.06.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 06/22/2012] [Accepted: 06/25/2012] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To investigate the mutations of SLC26A4 gene and the relevant phenotype in Chinese sporadic nonsyndromic hearing-impaired children. METHODS 195 Chinese sporadic nonsyndromic hearing-impaired children were subjected to microarray-based mutation detection for 9 hot spot mutations in four of the most common deafness-related genes (GJB2, SLC26A4, GJB3, and 12s rRNA). Subsequently, twenty-one patients with one SLC26A4 mutation detected by microarray were subjected to sequencing analysis of the whole SLC26A4 coding region and the splice sites in order to identify the second mutant allele. The inner ear malformation and hearing loss level were compared among different genotypes. RESULTS The incidence of genetic mutations was found to be 43.59% (85/195) in this patient group using CapitalBio Deafness Gene Mutation Detection Array Kit. A total of 34 children (17.44%) were found carrying the mutant SLC26A4 sequences. Thirteen (6.67%) children carried two mutant alleles of SLC26A4 and 21 (10.77%) children carried one mutant allele of SLC26A4. After the application of subsequent sequencing analysis, 13 mutational variants including 4 novel variants, two missense (p.D661G, p.N457D), one splice site mutation (IVS15+1G>A) and one frameshift mutation (624_632del9insACTTGGC), were identified in SLC26A4 gene in 15 of the 21 previously monoallelic patients. No second mutation was identified in the remaining 6 children. Biallelic mutations of SLC26A4 were identified in 20 of 21 children with enlarged vestibular aqueduct. CONCLUSIONS Our results demonstrated that genetic factors were important causes for sporadic nonsyndromic hearing loss in Chinese pediatric cases. Mutation of SLC26A4 is one of the major genetic causes in nonsyndromic hearing loss with inner ear malformation. IVS7-2A>G, 2168A>G and 1229C>T were the most frequent mutations identified in our studies. The combination of microarray testing and sequencing analysis is a useful and high-throughput method for the diagnosis of genetic hearing loss.
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Affiliation(s)
- Xiangyang Hu
- China Rehabilitation and Research Center for Deaf Children, Beijing 100029, People's Republic of China
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Cirello V, Bazzini C, Vezzoli V, Muzza M, Rodighiero S, Castorina P, Maffini A, Bottà G, Persani L, Beck-Peccoz P, Meyer G, Fugazzola L. Molecular and functional studies of 4 candidate loci in Pendred syndrome and nonsyndromic hearing loss. Mol Cell Endocrinol 2012; 351:342-50. [PMID: 22285650 DOI: 10.1016/j.mce.2012.01.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 01/09/2012] [Accepted: 01/13/2012] [Indexed: 12/13/2022]
Abstract
Patients with PS or non-syndromic deafness were submitted to genetic/functional analyzes of SLC26A4, of its binding domain for FOXI1 (FOXI1-DBD), of the transcription activator FOXI1, and of the potassium channel KCNJ10. SLC26A4 was the most frequently mutated gene. An altered intracellular localization with immunocytochemistry, and a hampered maturation process were demonstrated for two novel SLC26A4 variants. Biochemical and immunocytochemical analyzes led to the development of a more sensitive fluorometric functional assay able to reveal the partial loss-of-function of SLC26A4 mutations. A novel missense variant was found in FOXI1 gene, though functional analysis showed no significant impairment in the transcriptional activation of SLC26A4. Finally, 3 patients were found to harbor a variant in KCNJ10, which was classified as polymorphism. The novelty of the study resides in the analysis of all the 4 candidate genetic loci linked to PS/non-syndromic deafness, and in the precise definition of the thyroid phenotype. PS was invariably associated with biallelic mutations of SLC26A4, whereas the genetic origin of non-syndromic deafness remained largely undetermined, since monoallelic SLC26A4 variants accounted for one fourth of the cases and FOXI1 and KCNJ10 were not involved in this series.
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81
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Yuan Y, Zhang X, Huang S, Zuo L, Zhang G, Song Y, Wang G, Wang H, Huang D, Han D, Dai P. Common molecular etiologies are rare in nonsyndromic Tibetan Chinese patients with hearing impairment. PLoS One 2012; 7:e30720. [PMID: 22389666 PMCID: PMC3289614 DOI: 10.1371/journal.pone.0030720] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 12/20/2011] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Thirty thousand infants are born every year with congenital hearing impairment in mainland China. Racial and regional factors are important in clinical diagnosis of genetic deafness. However, molecular etiology of hearing impairment in the Tibetan Chinese population living in the Tibetan Plateau has not been investigated. To provide appropriate genetic testing and counseling to Tibetan families, we investigated molecular etiology of nonsyndromic deafness in this population. METHODS A total of 114 unrelated deaf Tibetan children from the Tibet Autonomous Region were enrolled. Five prominent deafness-related genes, GJB2, SLC26A4, GJB6, POU3F4, and mtDNA 12S rRNA, were analyzed. Inner ear development was evaluated by temporal CT. A total of 106 Tibetan hearing normal individuals were included as genetic controls. For radiological comparison, 120 patients, mainly of Han ethnicity, with sensorineural hearing loss were analyzed by temporal CT. RESULTS None of the Tibetan patients carried diallelic GJB2 or SLC26A4 mutations. Two patients with a history of aminoglycoside usage carried homogeneous mtDNA 12S rRNA A1555G mutation. Two controls were homozygous for 12S rRNA A1555G. There were no mutations in GJB6 or POU3F4. A diagnosis of inner ear malformation was made in 20.18% of the Tibetan patients and 21.67% of the Han deaf group. Enlarged vestibular aqueduct, the most common inner ear deformity, was not found in theTibetan patients, but was seen in 18.33% of the Han patients. Common molecular etiologies, GJB2 and SLC26A4 mutations, were rare in the Tibetan Chinese deaf population. CONCLUSION The mutation spectrum of hearing loss differs significantly between Chinese Tibetan patients and Han patients. The incidence of inner ear malformation in Tibetans is almost as high as that in Han deaf patients, but the types of malformation vary greatly. Hypoxia and special environment in plateau may be one cause of developmental inner ear deformity in this population.
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Affiliation(s)
- Yongyi Yuan
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
- Department of Otolaryngology, Hainan Branch of PLA General Hospital, Sanya, People's Republic of China
| | - Xun Zhang
- Department of Otolaryngology, 3rd hospital of Hebei Medical University, Shijiazhuang, Hebei Province, People's Republic of China
| | - Shasha Huang
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
| | - Lujie Zuo
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
- Department of Otolaryngology, 3rd hospital of Hebei Medical University, Shijiazhuang, Hebei Province, People's Republic of China
| | - Guozheng Zhang
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
- Department of Otolaryngology, 3rd hospital of Hebei Medical University, Shijiazhuang, Hebei Province, People's Republic of China
| | - Yueshuai Song
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
| | - Guojian Wang
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
- Department of Otolaryngology, Hainan Branch of PLA General Hospital, Sanya, People's Republic of China
| | - Hongtian Wang
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
| | - Deliang Huang
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
| | - Dongyi Han
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
| | - Pu Dai
- Department of Otolaryngology, PLA General Hospital, Beijing, People's Republic of China
- Department of Otolaryngology, Hainan Branch of PLA General Hospital, Sanya, People's Republic of China
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Presence of FXYD6 in the endolymphatic sac epithelia. Neurosci Lett 2012; 513:47-50. [PMID: 22343024 DOI: 10.1016/j.neulet.2012.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 02/02/2012] [Accepted: 02/02/2012] [Indexed: 11/20/2022]
Abstract
A homeostasis of the electrochemical properties and volume of the endolymph in the inner ear is essential for hearing and equilibrium sensing and is maintained by ion-transport across an epithelial tissue, the endolymphatic sac. One of the key proteins in the maintenance is Na(+), K(+)-ATPase. Although we previously found that the Na(+), K(+)-ATPase in the sac plays a pivotal role in the control of the endolymphatic volume, the mechanism remains unclear. Therefore, in this study, we examined the expression of FXYD6, a functional modulator of the Na(+), K(+)-ATPase, in the epithelial cells of the endolymphatic sac using various approaches. Laser capture microdissection RT-PCR was used to identify FXYD6 mRNA in the endolymphatic sac. Immunolabeling with the specific antibody showed that FXYD6 was predominantly expressed in the intermediate portion of the endolymphatic sac, and it was colocalized with the Na(+), K(+)-ATPase. Because the Na(+), K(+)-ATPase in this region is known to exhibit a high level of activity, an interaction of FXYD6 with this transporter may be critically involved in the regulation of the characteristics of the endolymph.
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Microarray-based mutation detection of pediatric sporadic nonsyndromic hearing loss in China. Int J Pediatr Otorhinolaryngol 2012; 76:235-9. [PMID: 22154049 DOI: 10.1016/j.ijporl.2011.11.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 11/12/2011] [Indexed: 01/26/2023]
Abstract
OBJECTIVE To investigate the molecular etiologic causes of sporadic nonsyndromic hearing loss in Chinese children. METHODS 179 sporadic nonsyndromic hearing loss children were subjected to microarray-based mutation detection for nine hot spot mutations in four of the most common deafness-related genes, including GJB2, SLC26A4, GJB3, and 12s rRNA. RESULTS The incidence of positive genetic errors was 43.58% with the current set of target genes in sporadic nonsyndromic hearing loss children. Among them, 25.14% of cases had genetic defects in GJB2, 16.76% of cases had pathogenic mutations in SLC26A4, 1.12% of cases were caused by 12s rRNA mutations, and GJB3 mutation was detected in 0.56% of this group of patients. CONCLUSIONS Our results demonstrated that genetic factors were important causes for sporadic nonsyndromic hearing loss in Chinese pediatric cases. Mutations of GJB2 and SLC26A4 are two major genetic causes, whereas mutations of GJB3 and 12s rRNA result in the development of hearing loss in a small percentage of sporadic nonsyndromic hearing loss cases. Microarray testing is a helpful and instrumental screening method in the diagnosis of genetic hearing loss.
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84
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Dossena S, Nofziger C, Tamma G, Bernardinelli E, Vanoni S, Nowak C, Grabmayer E, Kössler S, Stephan S, Patsch W, Paulmichl M. Molecular and functional characterization of human pendrin and its allelic variants. Cell Physiol Biochem 2011; 28:451-66. [PMID: 22116358 DOI: 10.1159/000335107] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2011] [Indexed: 12/13/2022] Open
Abstract
Pendrin (SLC26A4, PDS) is an electroneutral anion exchanger transporting I(-), Cl(-), HCO(3)(-), OH(-), SCN(-) and formate. In the thyroid, pendrin is expressed at the apical membrane of the follicular epithelium and may be involved in mediating apical iodide efflux into the follicle; in the inner ear, it plays a crucial role in the conditioning of the pH and ion composition of the endolymph; in the kidney, it may exert a role in pH homeostasis and regulation of blood pressure. Mutations of the pendrin gene can lead to syndromic and non-syndromic hearing loss with EVA (enlarged vestibular aqueduct). Functional tests of mutated pendrin allelic variants found in patients with Pendred syndrome or non-syndromic EVA (ns-EVA) revealed that the pathological phenotype is due to the reduction or loss of function of the ion transport activity. The diagnosis of Pendred syndrome and ns-EVA can be difficult because of the presence of phenocopies of Pendred syndrome and benign polymorphisms occurring in the general population. As a consequence, defining whether or not an allelic variant is pathogenic is crucial. Recently, we found that the two parameters used so far to assess the pathogenic potential of a mutation, i.e. low incidence in the control population, and substitution of evolutionary conserved amino acids, are not always reliable for predicting the functionality of pendrin allelic variants; actually, we identified mutations occurring with the same frequency in the cohort of hearing impaired patients and in the control group of normal hearing individuals. Moreover, we identified functional polymorphisms affecting highly conserved amino acids. As a general rule however, we observed a complete loss of function for all truncations and amino acid substitutions involving a proline. In this view, clinical and radiological studies should be combined with genetic and molecular studies for a definitive diagnosis. In performing genetic studies, the possibility that the mutation could affect regions other than the pendrin coding region, such as its promoter region and/or the coding regions of functionally related genes (FOXI1, KCNJ10), should be taken into account. The presence of benign polymorphisms in the population suggests that genetic studies should be corroborated by functional studies; in this context, the existence of hypo-functional variants and possible differences between the I(-)/Cl(-) and Cl(-)/HCO(3)(-) exchange activities should be carefully evaluated.
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Affiliation(s)
- Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria.
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Dror AA, Brownstein Z, Avraham KB. Integration of human and mouse genetics reveals pendrin function in hearing and deafness. Cell Physiol Biochem 2011; 28:535-44. [PMID: 22116368 DOI: 10.1159/000335163] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2011] [Indexed: 12/21/2022] Open
Abstract
Genomic technology has completely changed the way in which we are able to diagnose human genetic mutations. Genomic techniques such as the polymerase chain reaction, linkage analysis, Sanger sequencing, and most recently, massively parallel sequencing, have allowed researchers and clinicians to identify mutations for patients with Pendred syndrome and DFNB4 non-syndromic hearing loss. While thus far most of the mutations have been in the SLC26A4 gene coding for the pendrin protein, other genetic mutations may contribute to these phenotypes as well. Furthermore, mouse models for deafness have been invaluable to help determine the mechanisms for SLC26A4-associated deafness. Further work in these areas of research will help define genotype-phenotype correlations and develop methods for therapy in the future.
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Affiliation(s)
- Amiel A Dror
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Dossena S, Nofziger C, Lang F, Valenti G, Paulmichl M. The ESF meeting on "The proteomics, epigenetics and pharmacogenetics of pendrin". Cell Physiol Biochem 2011; 28:377-84. [PMID: 22116352 DOI: 10.1159/000335101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2011] [Indexed: 12/25/2022] Open
Abstract
Human pendrin (SCL26A4, PDS) is a 780 amino acid integral membrane protein with transport function. It acts as an electroneutral, sodium-independent anion exchanger for a wide range of anions, such as iodide, chloride, formate, bicarbonate, hydroxide and thiocyanate. Pendrin expression was originally described in the thyroid gland, kidney and inner ear. Accordingly, pendrin mutations with reduction or loss of transport function result in thyroid and inner ear abnormalities, manifested as syndromic (Pendred syndrome) and non-syndromic hearing loss with an enlarged vestibular aqueduct (ns-EVA). Pendred syndrome, the most common form of syndromic deafness, is an autosomal recessive disease characterized by sensorineural deafness due to inner ear malformations and a partial iodide organification defect that may lead to thyroid goiter. Later, it became evident that not only pendrin loss of function, but also up-regulation could participate in the pathogenesis of human diseases. Indeed, despite the absence of kidney dysfunction in Pendred syndrome patients, evidence exists that pendrin also plays a crucial role in this organ, with a potential involvement in the pathogenesis of hypertension. In addition, recent data underscore the role of pendrin in exacerbations of respiratory distresses including bronchial asthma and chronic obstructive pulmonary disease (COPD). Pendrin expression in other organs such as mammary gland, testis, placenta, endometrium and liver point to new, underscored pendrin functions that deserve to be further investigated.
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Affiliation(s)
- Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
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Bizhanova A, Chew TL, Khuon S, Kopp P. Analysis of cellular localization and function of carboxy-terminal mutants of pendrin. Cell Physiol Biochem 2011; 28:423-34. [PMID: 22116356 PMCID: PMC3709185 DOI: 10.1159/000335105] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2011] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Iodide uptake at the basolateral membrane and iodide efflux at the apical membrane of thyrocytes, essential steps in the biosynthesis of thyroid hormone, are stimulated by thyroid stimulating hormone (TSH). Pendrin (SLC26A4) is inserted into the apical membrane of thyrocytes and thought to be involved in mediating iodide efflux. METHODS We determined the effects of carboxy-terminal mutations of pendrin on the cellular localization and the ability to transport iodide. RESULTS After exposure to forskolin, the membrane abundance of wild type pendrin and iodide efflux increase. Truncation mutants lead to complete intracellular retention. Elimination of the distal part of the sulfate transporter and antisigma factor antagonist (STAS) domain with retention of the putative protein kinase A (PKA) phosphorylation site (RKDT 714-717) results in residual membrane insertion and a partial loss of function. Deletion of the PKA site results in decreased basal function and membrane insertion and abolishes the response to forskolin. CONCLUSION Pendrin membrane abundance and its ability to mediate iodide efflux increase after activation of the PKA pathway. Elimination of the PKA site abolishes the response to forskolin but partial basal function and membrane insertion are maintained.
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Affiliation(s)
- Aigerim Bizhanova
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago
| | - Teng-Leong Chew
- Cell Imaging Facility, Feinberg School of Medicine, Northwestern University, Chicago
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago
| | - Satya Khuon
- Cell Imaging Facility, Feinberg School of Medicine, Northwestern University, Chicago
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago
| | - Peter Kopp
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago
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Rozenfeld J, Efrati E, Adler L, Tal O, Carrithers SL, Alper SL, Zelikovic I. Transcriptional regulation of the pendrin gene. Cell Physiol Biochem 2011; 28:385-96. [PMID: 22116353 DOI: 10.1159/000335100] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2011] [Indexed: 12/20/2022] Open
Abstract
Pendrin (SLC26A4), a Cl(-)/anion exchanger encoded by the gene PDS, is highly expressed in the kidney, thyroid and inner ear epithelia and is essential for bicarbonate secretion/chloride reabsorption, iodide accumulation and endolymph ion balance, respectively. The molecular mechanisms controlling pendrin activity in renal, thyroid and inner ear epithelia have been the subject of recent studies. The effects of ambient pH, the hormone aldosterone and the peptide uroguanylin (UGN; the "intestinal natriuretic hormone"), known modulators of electrolyte balance, on transcription of the pendrin gene, have been investigated. Luciferase reporter plasmids containing different length fragments of the human PDS (hPDS) promoter were transfected into renal HEK293, thyroid LA2, and inner ear VOT36 epithelial cells. Acidic pH decreased and alkaline pH increased hPDS promoter activity in transfected HEK293 and VOT36, but not in LA2 cells. Aldosterone reduced hPDS promoter activity in HEK293 but had no effect in LA2 and VOT36 cells. These pH and aldosterone-induced effects on the hPDS promoter occurred within 96-bp and 89-bp regions, respectively, which likely contain distinct response elements to these modulators. Injection of UGN into mice resulted in decreased pendrin mRNA and protein expression in the kidney. Exposure of transfected HEK293 to UGN decreased hPDS promoter activity. The findings provided evidence for the presence of a UGN response element within the 96-bp region overlapping with the pH response element on the hPDS promoter. Pendrin is also expressed in airway epithelium. The cytokins interleukin 4 (IL-4) and interleukin-13 (IL-13), known regulators of airway surface function, have been shown to increase hPDS promoter activity by a STAT6-dependent mechanism. In conclusion, systemic pH, the hormone aldosterone, and the peptide UGN influence renal tubular pendrin gene expression and, perhaps, pendrin-mediated Cl(-)/HCO(3)(-) exchange at the transcriptional level. Pendrin-driven anion transport in the endolymph and at the airway surface may be regulated transcriptionally by systemic pH and IL-3/IL-4, respectively. The distinct response elements and the corresponding transcription factors mediating the effect of these modulators on the PDS promoter remain to be identified and characterized.
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Affiliation(s)
- Julia Rozenfeld
- Laboratory of Developmental Nephrology, Department of Physiology and Biophysics, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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89
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Abstract
The thyroid hormones thyroxine (T(4)) and triiodothyronine (T(3)) play key roles in regulating development, growth and metabolism in pre- and postnatal life. Iodide (I(-)) is an essential component of the thyroid hormones and is accumulated avidly by the thyroid gland. The rarity of elemental iodine and I(-) in the environment challenges the thyroid to orchestrate a remarkable series of transport processes that ultimately ensure sufficient levels for hormone synthesis. In addition to actively extracting circulating I(-), thyroid follicular epithelial cells must also translocate I(-) into a central intrafollicular compartment, where thyroglobulin is iodinated to form the protein precursor to T(4) and T(3). In the last decade, several bodies of evidence render questionable the notion that I(-) exits thyrocytes solely via the Cl(-)/I(-) exchanger Pendrin (SLC26A4), therefore necessitating reconsideration of several other candidate I(-) conduits: the Cl(-)/H(+) antiporter, CLC-5, the cystic fibrosis transmembrane conductance regulator (CFTR) and the sodium monocarboxylic acid transporter (SMCT1).
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Affiliation(s)
- Peying Fong
- Department of Anatomy and Physiology, Kansas State University College of Veterinary Medicine, Manhattan, KS 66506, USA.
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90
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Garnett JP, Hickman E, Burrows R, Hegyi P, Tiszlavicz L, Cuthbert AW, Fong P, Gray MA. Novel role for pendrin in orchestrating bicarbonate secretion in cystic fibrosis transmembrane conductance regulator (CFTR)-expressing airway serous cells. J Biol Chem 2011; 286:41069-82. [PMID: 21914796 DOI: 10.1074/jbc.m111.266734] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In most HCO(3)(-)-secreting epithelial tissues, SLC26 Cl(-)/HCO(3)(-) transporters work in concert with the cystic fibrosis transmembrane conductance regulator (CFTR) to regulate the magnitude and composition of the secreted fluid, a process that is vital for normal tissue function. By contrast, CFTR is regarded as the only exit pathway for HCO(3)(-) in the airways. Here we show that Cl(-)/HCO(3)(-) anion exchange makes a major contribution to transcellular HCO(3)(-) transport in airway serous cells. Real-time measurement of intracellular pH from polarized cultures of human Calu-3 cells demonstrated cAMP/PKA-activated Cl(-)-dependent HCO(3)(-) transport across the luminal membrane via CFTR-dependent coupled Cl(-)/HCO(3)(-) anion exchange. The pharmacological and functional profile of the luminal anion exchanger was consistent with SLC26A4 (pendrin), which was shown to be expressed by quantitative RT-PCR, Western blot, and immunofluorescence. Pendrin-mediated anion exchange activity was confirmed by shRNA pendrin knockdown (KD), which markedly reduced cAMP-activated Cl(-)/HCO(3)(-) exchange. To establish the relative roles of CFTR and pendrin in net HCO(3)(-) secretion, transepithelial liquid secretion rate and liquid pH were measured in wild type, pendrin KD, and CFTR KD cells. cAMP/PKA increased the rate and pH of the secreted fluid. Inhibiting CFTR reduced the rate of liquid secretion but not the pH, whereas decreasing pendrin activity lowered pH with little effect on volume. These results establish that CFTR predominately controls the rate of liquid secretion, whereas pendrin regulates the composition of the secreted fluid and identifies a critical role for this anion exchanger in transcellular HCO(3)(-) secretion in airway serous cells.
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Affiliation(s)
- James P Garnett
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
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91
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Tang J, Pecka JL, Tan X, Beisel KW, He DZZ. Engineered pendrin protein, an anion transporter and molecular motor. J Biol Chem 2011; 286:31014-31021. [PMID: 21757707 PMCID: PMC3162460 DOI: 10.1074/jbc.m111.259564] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 07/12/2011] [Indexed: 11/06/2022] Open
Abstract
Pendrin and prestin both belong to a distinct anion transporter family called solute carrier protein 26A, or SLC26A. Pendrin (SLC26A4) is a chloride-iodide transporter that is found at the luminal membrane of follicular cells in the thyroid gland as well as in the endolymphatic duct and sac of the inner ear, whereas prestin (SLC26A5) is expressed in the plasma membrane of cochlear outer hair cells and functions as a unique voltage-dependent motor. We recently identified a motif that is critical for the motor function of prestin. We questioned whether it was possible to create a chimeric pendrin protein with motor capability by integrating this motility motif from prestin. The chimeric pendrin was constructed by substituting residues 160-179 in human pendrin with residues 156-169 from gerbil prestin. Non-linear capacitance and somatic motility, two hallmarks representing prestin function, were measured from chimeric pendrin-transfected human embryonic kidney 293 cells using the voltage clamp technique and photodiode-based displacement measurement system. We showed that this 14-amino acid substitution from prestin was able to confer pendrin with voltage-dependent motor capability despite the amino acid sequence disparity between pendrin and prestin. The molecular mechanism that facilitates motor function appeared to be the same as prestin because the motor activity depended on the concentration of intracellular chloride and was blocked by salicylate treatment. Radioisotope-labeled formate uptake measurements showed that the chimeric pendrin protein retained the capability to transport formate, suggesting that the gain of motor function was not at the expense of its inherent transport capability. Thus, the engineered pendrin was capable of both transporting anions and generating force.
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Affiliation(s)
- Jie Tang
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178
| | - Jason L Pecka
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178
| | - Xiaodong Tan
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178
| | - Kirk W Beisel
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178
| | - David Z Z He
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178.
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92
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Attanasio R, Scinicariello F, Blount BC, Valentin-Blasini L, Rogers KA, Nguyen DC, Murray HE. Pendrin mediates uptake of perchlorate in a mammalian in vitro system. CHEMOSPHERE 2011; 84:1484-1488. [PMID: 21550633 DOI: 10.1016/j.chemosphere.2011.04.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 03/21/2011] [Accepted: 04/08/2011] [Indexed: 05/30/2023]
Abstract
Perchlorate is a known endocrine disruptor present in groundwater, vegetables and dairy food products in many regions of the United States. It interferes with the uptake of iodide into the thyrocyte by the sodium-iodide symporter at the basolateral surface, thus potentially disrupting the synthesis of thyroid hormone. Because transport of iodide from the thyroid follicular cells to the follicular lumen is mediated by the protein pendrin at the apical surface, we hypothesized that perchlorate may also interact with this protein. Therefore, HeLa cells were transfected with the human SLC26A4 gene, which encodes pendrin, to generate an in vitro mammalian system expressing the recombinant pendrin protein (HeLa-PDS). The HeLa-PDS cells, along with untransfected cells, were then cultured in presence of iodide and/or perchlorate. Intracellular levels of these two chemicals were measured by ion chromatography tandem mass spectrometry. Results from this study show that iodide and perchlorate uptake increases significantly in HeLa-PDS cells as compared to untransfected cells. Thus, recombinant HeLa cells expressing pendrin protein accumulate iodide and perchlorate intracellularly, indicating that pendrin is involved in the uptake of perchlorate. Additional results from this study suggest that iodide and perchlorate competitively inhibit each other for uptake by pendrin. The ability of perchlorate to compete with iodide for uptake by both basal and apical transporters may increase the potential of perturbation of thyroid homeostasis and therefore the estimated risk posed to susceptible human populations.
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93
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Lu YC, Wu CC, Shen WS, Yang TH, Yeh TH, Chen PJ, Yu IS, Lin SW, Wong JM, Chang Q, Lin X, Hsu CJ. Establishment of a knock-in mouse model with the SLC26A4 c.919-2A>G mutation and characterization of its pathology. PLoS One 2011; 6:e22150. [PMID: 21811566 PMCID: PMC3141011 DOI: 10.1371/journal.pone.0022150] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 06/19/2011] [Indexed: 11/18/2022] Open
Abstract
Recessive mutations in the SLC26A4 gene are a common cause of hereditary hearing impairment worldwide. Previous studies have demonstrated that different SLC26A4 mutations may have different pathogenetic mechanisms. In the present study, we established a knock-in mouse model (i.e., Slc26a4tm1Dontuh/tm1Dontuh mice) homozygous for the c.919-2A>G mutation, which is a common mutation in East Asians. Mice were then subjected to audiologic assessment, a battery of vestibular evaluations, and inner ear morphological studies. All Slc26a4tm1Dontuh/tm1Dontuh mice revealed profound hearing loss, whereas 46% mice demonstrated pronounced head tilting and circling behaviors. There was a significant difference in the vestibular performance between wild-type and Slc26a4tm1Dontuh/tm1Dontuh mice, especially those exhibiting circling behavior. Inner ear morphological examination of Slc26a4tm1Dontuh/tm1Dontuh mice revealed an enlarged endolymphatic duct, vestibular aqueduct and sac, atrophy of stria vascularis, deformity of otoconia in the vestibular organs, consistent degeneration of cochlear hair cells, and variable degeneration of vestibular hair cells. Audiologic and inner ear morphological features of Slc26a4tm1Dontuh/tm1Dontuh mice were reminiscent of those observed in humans. These features were also similar to those previously reported in both knock-out Slc26a4−/− mice and Slc26a4loop/loop mice with the Slc26a4 p.S408F mutation, albeit the severity of vestibular hair cell degeneration appeared different among the three mouse strains.
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Affiliation(s)
- Ying-Chang Lu
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Wen-Sheng Shen
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Ting-Hua Yang
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Te-Huei Yeh
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - Pei-Jer Chen
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - I-Shing Yu
- Transgenic Mouse Models Core (TMMC), Division of Genomic Medicine, Research Center for Medical Excellence, National Taiwan University, Taipei, Taiwan
| | - Shu-Wha Lin
- Transgenic Mouse Models Core (TMMC), Division of Genomic Medicine, Research Center for Medical Excellence, National Taiwan University, Taipei, Taiwan
| | - Jau-Min Wong
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Qing Chang
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Chuan-Jen Hsu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
- Department of Otolaryngology, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail:
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94
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SLC26A4 expression among autoimmune thyroid tissues. Immunobiology 2011; 216:571-8. [DOI: 10.1016/j.imbio.2010.09.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 09/28/2010] [Accepted: 09/28/2010] [Indexed: 11/18/2022]
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95
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Kopp P, Bizhanova A. Clinical and molecular characteristics of Pendred syndrome. ANNALES D'ENDOCRINOLOGIE 2011; 72:88-94. [PMID: 21511235 DOI: 10.1016/j.ando.2011.03.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Pendred syndrome is an autosomal recessive disorder defined by sensorineural deafness, goiter and a partial defect in the organification of iodide. It is caused by biallelic mutations in the SLC26A4 gene, which encodes pendrin, a multifunctional anion exchanger. At the level of the inner ear, pendrin is important for the creation of a normal endolymph composition and the maintenance of the endocochlear potential. In the thyroid, pendrin is expressed at the apical membrane of thyroid follicular cells and it appears to be involved in mediating iodide efflux into the lumen and/or maintenance of the follicular pH. Goiter development and hypothyroidism vary among affected individuals and seem to be partially dependent on nutritional iodide intake. In the kidney, pendrin functions as a chloride/bicarbonate exchanger. Elucidation of the molecular basis of Pendred syndrome and the function of pendrin has provided unexpected novel insights into the pathophysiology of the inner ear, thyroid hormone synthesis, and chloride/bicarbonate exchange in the kidney.
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Affiliation(s)
- P Kopp
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago IL60611, USA.
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96
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Almomani EY, Chu CY, Cordat E. Mis-trafficking of bicarbonate transporters: implications to human diseasesThis paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process. Biochem Cell Biol 2011; 89:157-77. [DOI: 10.1139/o10-153] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bicarbonate is a waste product of mitochondrial respiration and one of the main buffers in the human body. Thus, bicarbonate transporters play an essential role in maintaining acid-base balance but also during fetal development as they ensure tight regulation of cytosolic and extracellular environments. Bicarbonate transporters belong to two gene families, SLC4A and SLC26A. Proteins from these two families are widely expressed, and thus mutations in their genes result in various diseases that affect bones, pancreas, reproduction, brain, kidneys, eyes, heart, thyroid, red blood cells, and lungs. In this minireview, we discuss the current state of knowledge regarding the effect of SLC4A and SLC26A mutants, with a special emphasis on mutants that have been studied in mammalian cell lines and how they correlate with phenotypes observed in mice models.
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Affiliation(s)
- Ensaf Y. Almomani
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Carmen Y.S. Chu
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Emmanuelle Cordat
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
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97
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Yoon H, Lee DJ, Kim MH, Bok J. Identification of genes concordantly expressed with Atoh1 during inner ear development. Anat Cell Biol 2011; 44:69-78. [PMID: 21519551 PMCID: PMC3080010 DOI: 10.5115/acb.2011.44.1.69] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 12/02/2010] [Accepted: 12/15/2010] [Indexed: 01/19/2023] Open
Abstract
The inner ear is composed of a cochlear duct and five vestibular organs in which mechanosensory hair cells play critical roles in receiving and relaying sound and balance signals to the brain. To identify novel genes associated with hair cell differentiation or function, we analyzed an archived gene expression dataset from embryonic mouse inner ear tissues. Since atonal homolog 1a (Atoh1) is a well known factor required for hair cell differentiation, we searched for genes expressed in a similar pattern with Atoh1 during inner ear development. The list from our analysis includes many genes previously reported to be involved in hair cell differentiation such as Myo6, Tecta, Myo7a, Cdh23, Atp6v1b1, and Gfi1. In addition, we identified many other genes that have not been associated with hair cell differentiation, including Tekt2, Spag6, Smpx, Lmod1, Myh7b, Kif9, Ttyh1, Scn11a and Cnga2. We examined expression patterns of some of the newly identified genes using real-time polymerase chain reaction and in situ hybridization. For example, Smpx and Tekt2, which are regulators for cytoskeletal dynamics, were shown specifically expressed in the hair cells, suggesting a possible role in hair cell differentiation or function. Here, by reanalyzing archived genetic profiling data, we identified a list of novel genes possibly involved in hair cell differentiation.
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Affiliation(s)
- Heejei Yoon
- Department of Anatomy, Brain Korea 21 Project for Medical Science, College of Medicine, Yonsei University, Seoul, Korea
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98
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Kim HM, Wangemann P. Epithelial cell stretching and luminal acidification lead to a retarded development of stria vascularis and deafness in mice lacking pendrin. PLoS One 2011; 6:e17949. [PMID: 21423764 PMCID: PMC3056798 DOI: 10.1371/journal.pone.0017949] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 02/16/2011] [Indexed: 12/13/2022] Open
Abstract
Loss-of-function mutations of SLC26A4/pendrin are among the most prevalent causes of deafness. Deafness and vestibular dysfunction in the corresponding mouse model, Slc26a4−/−, are associated with an enlargement and acidification of the membranous labyrinth. Here we relate the onset of expression of the HCO3− transporter pendrin to the luminal pH and to enlargement-associated epithelial cell stretching. We determined expression with immunocytochemistry, cell stretching by digital morphometry and pH with double-barreled ion-selective electrodes. Pendrin was first expressed in the endolymphatic sac at embryonic day (E) 11.5, in the cochlear hook-region at E13.5, in the utricle and saccule at E14.5, in ampullae at E16.5, and in the upper turn of the cochlea at E17.5. Epithelial cell stretching in Slc26a4−/− mice began at E14.5. pH changes occurred first in the cochlea at E15.5 and in the endolymphatic sac at E17.5. At postnatal day 2, stria vascularis, outer sulcus and Reissner's membrane epithelial cells, and utricular and saccular transitional cells were stretched, whereas sensory cells in the cochlea, utricle and saccule did not differ between Slc26a4+/− and Slc26a4−/− mice. Structural development of stria vascularis, including vascularization, was retarded in Slc26a4−/− mice. In conclusion, the data demonstrate that the enlargement and stretching of non-sensory epithelial cells precedes luminal acidification in the cochlea and the endolymphatic sac. Stretching and luminal acidification may alter cell-to-cell communication and lead to the observed retarded development of stria vascularis, which may be an important step on the path to deafness in Slc26a4−/− mice, and possibly in humans, lacking functional pendrin expression.
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Affiliation(s)
- Hyoung-Mi Kim
- Anatomy and Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
| | - Philine Wangemann
- Anatomy and Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
- * E-mail:
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99
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McCormick JA, Ellison DH. The WNKs: atypical protein kinases with pleiotropic actions. Physiol Rev 2011; 91:177-219. [PMID: 21248166 DOI: 10.1152/physrev.00017.2010] [Citation(s) in RCA: 201] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
WNKs are serine/threonine kinases that comprise a unique branch of the kinome. They are so-named owing to the unusual placement of an essential catalytic lysine. WNKs have now been identified in diverse organisms. In humans and other mammals, four genes encode WNKs. WNKs are widely expressed at the message level, although data on protein expression is more limited. Soon after the WNKs were identified, mutations in genes encoding WNK1 and -4 were determined to cause the human disease familial hyperkalemic hypertension (also known as pseudohypoaldosteronism II, or Gordon's Syndrome). For this reason, a major focus of investigation has been to dissect the role of WNK kinases in renal regulation of ion transport. More recently, a different mutation in WNK1 was identified as the cause of hereditary sensory and autonomic neuropathy type II, an early-onset autosomal disease of peripheral sensory nerves. Thus the WNKs represent an important family of potential targets for the treatment of human disease, and further elucidation of their physiological actions outside of the kidney and brain is necessary. In this review, we describe the gene structure and mechanisms regulating expression and activity of the WNKs. Subsequently, we outline substrates and targets of WNKs as well as effects of WNKs on cellular physiology, both in the kidney and elsewhere. Next, consequences of these effects on integrated physiological function are outlined. Finally, we discuss the known and putative pathophysiological relevance of the WNKs.
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Affiliation(s)
- James A McCormick
- Division of Nephrology and Hypertension, Oregon Health and Science University and Veterans Affairs Medical Center, Portland, Oregon 97239, USA.
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100
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Abstract
Mutations in the anion exchanger pendrin are responsible for Pendred syndrome, an autosomal recessive disease characterized by deafness and goitre. Pendrin is highly expressed in kidney collecting ducts, where it acts as a chloride/bicarbonate exchanger and thereby contributes to the regulation of acid–base homoeostasis and blood pressure. The present study aimed to characterize the intrinsic properties of pendrin. Mouse pendrin was transfected in HEK (human embryonic kidney) 293 and OKP (opossum kidney proximal tubule) cells and its activity was determined by monitoring changes in the intracellular pH induced by variations of transmembrane anion gradients. Combining measurements of pendrin activity with mathematical modelling we found that its affinity for Cl−, HCO3− and OH− varies with intracellular pH, with increased activity at low intracellular pH. Maximal pendrin activity was also stimulated at low extracellular pH, suggesting the presence of both intracellular and extracellular proton regulatory sites. We identified five putative pendrin glycosylation sites, only two of which are used. Mutagenesis-induced disruption of pendrin glycosylation did not alter its cell-surface expression or polarized targeting to the apical membrane and basal activity, but fully abrogated its sensitivity to extracellular pH. The hither to unknown regulation of pendrin by external pH may constitute a key mechanism in controlling ionic exchanges across the collecting duct and inner ear.
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