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Kiriya M, Kawashima A, Fujiwara Y, Tanimura Y, Yoshihara A, Nakamura Y, Tanigawa K, Kondo T, Suzuki K. Thyroglobulin regulates the expression and localization of the novel iodide transporter solute carrier family 26 member 7 (SLC26A7) in thyrocytes. Endocr J 2022; 69:1217-1225. [PMID: 35644541 DOI: 10.1507/endocrj.ej22-0082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Solute carrier family 26 member 7 (SLC26A7), identified as a causative gene for congenital hypothyroidism, was found to be a novel iodide transporter expressed on the apical side of the follicular epithelium of the thyroid. We recently showed that TSH suppressed the expression of SLC26A7 and induces its localization to the plasma membrane, where it functions. We also showed that the ability of TSH to induce thyroid hormone synthesis is completely reversed by an autocrine negative-feedback action of thyroglobulin (Tg) stored in the follicular lumen. In the present study, we investigated the potential effect of follicular Tg on SLC26A7 expression and found that follicular Tg significantly suppressed the promoter activity, mRNA level, and protein level of SLC26A7 in rat thyroid FRTL-5 cells. In addition, follicular Tg inhibited the ability of TSH to induce the membrane localization of SLC26A7. In rat thyroid sections, the expression of SLC26A7 was weaker in follicles with a higher concentration of Tg, as evidenced by immunofluorescence staining. These results indicate that Tg stored in the follicular lumen is a feedback suppressor of the expression and membrane localization of SLC26A7, thereby downregulating the transport of iodide into the follicular lumen.
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Affiliation(s)
- Mitsuo Kiriya
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
- Department of Pathology, Faculty of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Akira Kawashima
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
| | - Yoko Fujiwara
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
| | - Yuta Tanimura
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
| | - Aya Yoshihara
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
- Center for Medical Education, Faculty of Medicine, Toho University, Tokyo 143-8540, Japan
| | - Yasuhiro Nakamura
- Center for Promotion of Pharmaceutical Education & Research, Faculty of Pharma-Science, Teikyo University, Tokyo 173-8605, Japan
| | - Kazunari Tanigawa
- Department of Molecular Pharmaceutics, Faculty of Pharma-Science, Teikyo University, Tokyo 173-8605, Japan
| | - Tetsuo Kondo
- Department of Pathology, Faculty of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Koichi Suzuki
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
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Tanimura Y, Kiriya M, Kawashima A, Mori H, Luo Y, Kondo T, Suzuki K. Regulation of solute carrier family 26 member 7 (Slc26a7) by thyroid stimulating hormone in thyrocytes. Endocr J 2021; 68:691-699. [PMID: 33583874 DOI: 10.1507/endocrj.ej20-0502] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Iodine transportation is an important step in thyroid hormone biosynthesis. Uptake of iodine into the thyroid follicle is mediated mainly by the basolateral sodium-iodide symporter (NIS or solute carrier family 5 member 5: SLC5A5), and iodine efflux across the apical membrane into the follicular lumen is mediated by pendrin (SLC26A4). In addition to these transporters, SLC26A7, which has recently been identified as a causative gene for congenital hypothyroidism, was found to encode a novel apical iodine transporter in the thyroid. Although SLC5A5 and SLC26A4 have been well-characterized, little is known about SLC26A7, including its regulation by TSH, the central hormone regulator of thyroid function. Using rat thyroid FRTL-5 cells, we showed that the mRNA levels of Slc26a7 and Slc26a4, two apical iodine transporters responsible for iodine efflux, were suppressed by TSH, whereas the mRNA level of Slc5a5 was induced. Forskolin and dibutyryl cAMP (dbcAMP) had the same effect as that of TSH on the mRNA levels of these transporters. TSH, forskolin and dbcAMP also had suppressive effects on SLC26A7 promoter activity, as assessed by luciferase reporter gene assays, and protein levels, as determined by Western blot analysis. TSH, forskolin and dbcAMP also induced strong localization of Slc26a7 to the cell membrane according to immunofluorescence staining and confocal laser scanning microscopy. Together, these results suggest that TSH suppresses the expression level of Slc26a7 but induces its accumulation at the cell membrane, where it functions as an iodine transporter.
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Affiliation(s)
- Yuta Tanimura
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Itabashi, Tokyo 173-8605, Japan
- Department of Pathology, Faculty of Medicine, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan
| | - Mitsuo Kiriya
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Itabashi, Tokyo 173-8605, Japan
| | - Akira Kawashima
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Itabashi, Tokyo 173-8605, Japan
| | - Hitomi Mori
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Itabashi, Tokyo 173-8605, Japan
| | - Yuqian Luo
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Itabashi, Tokyo 173-8605, Japan
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital and Jiangsu Key Laboratory for Molecular Medicine, Nanjing University Medical School, Nanjing 210008, China
| | - Tetsuo Kondo
- Department of Pathology, Faculty of Medicine, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan
| | - Koichi Suzuki
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Itabashi, Tokyo 173-8605, Japan
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Kanavy DM, McNulty SM, Jairath MK, Brnich SE, Bizon C, Powell BC, Berg JS. Comparative analysis of functional assay evidence use by ClinGen Variant Curation Expert Panels. Genome Med 2019; 11:77. [PMID: 31783775 PMCID: PMC6884856 DOI: 10.1186/s13073-019-0683-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 11/05/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The 2015 American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) guidelines for clinical sequence variant interpretation state that "well-established" functional studies can be used as evidence in variant classification. These guidelines articulated key attributes of functional data, including that assays should reflect the biological environment and be analytically sound; however, details of how to evaluate these attributes were left to expert judgment. The Clinical Genome Resource (ClinGen) designates Variant Curation Expert Panels (VCEPs) in specific disease areas to make gene-centric specifications to the ACMG/AMP guidelines, including more specific definitions of appropriate functional assays. We set out to evaluate the existing VCEP guidelines for functional assays. METHODS We evaluated the functional criteria (PS3/BS3) of six VCEPs (CDH1, Hearing Loss, Inherited Cardiomyopathy-MYH7, PAH, PTEN, RASopathy). We then established criteria for evaluating functional studies based on disease mechanism, general class of assay, and the characteristics of specific assay instances described in the primary literature. Using these criteria, we extensively curated assay instances cited by each VCEP in their pilot variant classification to analyze VCEP recommendations and their use in the interpretation of functional studies. RESULTS Unsurprisingly, our analysis highlighted the breadth of VCEP-approved assays, reflecting the diversity of disease mechanisms among VCEPs. We also noted substantial variability between VCEPs in the method used to select these assays and in the approach used to specify strength modifications, as well as differences in suggested validation parameters. Importantly, we observed discrepancies between the parameters VCEPs specified as required for approved assay instances and the fulfillment of these requirements in the individual assays cited in pilot variant interpretation. CONCLUSIONS Interpretation of the intricacies of functional assays often requires expert-level knowledge of the gene and disease, and current VCEP recommendations for functional assay evidence are a useful tool to improve the accessibility of functional data by providing a starting point for curators to identify approved functional assays and key metrics. However, our analysis suggests that further guidance is needed to standardize this process and ensure consistency in the application of functional evidence.
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Affiliation(s)
- Dona M Kanavy
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Shannon M McNulty
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Meera K Jairath
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sarah E Brnich
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Chris Bizon
- Renaissance Computing Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Bradford C Powell
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jonathan S Berg
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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4
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Oza AM, DiStefano MT, Hemphill SE, Cushman BJ, Grant AR, Siegert RK, Shen J, Chapin A, Boczek NJ, Schimmenti LA, Murry JB, Hasadsri L, Nara K, Kenna M, Booth KT, Azaiez H, Griffith A, Avraham KB, Kremer H, Rehm HL, Amr SS, Abou Tayoun AN. Expert specification of the ACMG/AMP variant interpretation guidelines for genetic hearing loss. Hum Mutat 2019; 39:1593-1613. [PMID: 30311386 DOI: 10.1002/humu.23630] [Citation(s) in RCA: 291] [Impact Index Per Article: 58.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/23/2018] [Accepted: 08/25/2018] [Indexed: 12/23/2022]
Abstract
Due to the high genetic heterogeneity of hearing loss (HL), current clinical testing includes sequencing large numbers of genes, which often yields a significant number of novel variants. Therefore, the standardization of variant interpretation is crucial to provide consistent and accurate diagnoses. The Hearing Loss Variant Curation Expert Panel was created within the Clinical Genome Resource to provide expert guidance for standardized genomic interpretation in the context of HL. As one of its major tasks, our Expert Panel has adapted the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines for the interpretation of sequence variants in HL genes. Here, we provide a comprehensive illustration of the newly specified ACMG/AMP HL rules. Three rules remained unchanged, four rules were removed, and the remaining 21 rules were specified. These rules were further validated and refined using a pilot set of 51 variants assessed by curators and disease experts. Of the 51 variants evaluated in the pilot, 37% (19/51) changed category based upon application of the expert panel specified rules and/or aggregation of evidence across laboratories. These HL-specific ACMG/AMP rules will help standardize variant interpretation, ultimately leading to better care for individuals with HL.
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Affiliation(s)
- Andrea M Oza
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts.,Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Boston, Massachusetts
| | - Marina T DiStefano
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - Sarah E Hemphill
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Brandon J Cushman
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Andrew R Grant
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Rebecca K Siegert
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Jun Shen
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts.,Harvard Medical School, Boston, Massachusetts.,Department of Pathology, Brigham & Women's Hospital, Boston, Massachusetts
| | | | - Nicole J Boczek
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Lisa A Schimmenti
- Department of Otorhinolaryngology, Clinical Genomics and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Jaclyn B Murry
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Linda Hasadsri
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Kiyomitsu Nara
- Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Margaret Kenna
- Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Boston, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - Kevin T Booth
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospital and Clinics, Iowa City, Iowa.,The Interdisciplinary Graduate Program in Molecular Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Hela Azaiez
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa Hospital and Clinics, Iowa City, Iowa
| | - Andrew Griffith
- Audiology Unit, National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, Bethesda, Maryland
| | - Karen B Avraham
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Hannie Kremer
- Department of Otorhinolaryngology and Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Heidi L Rehm
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts.,Harvard Medical School, Boston, Massachusetts.,Center for Genomic Medicine, Massachusetts General Hospital, Boston, Massachusetts.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Sami S Amr
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts.,Harvard Medical School, Boston, Massachusetts.,Department of Pathology, Brigham & Women's Hospital, Boston, Massachusetts
| | - Ahmad N Abou Tayoun
- The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
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5
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Ishii J, Suzuki A, Kimura T, Tateyama M, Tanaka T, Yazawa T, Arimasu Y, Chen IS, Aoyama K, Kubo Y, Saitoh S, Mizuno H, Kamma H. Congenital goitrous hypothyroidism is caused by dysfunction of the iodide transporter SLC26A7. Commun Biol 2019; 2:270. [PMID: 31372509 PMCID: PMC6656751 DOI: 10.1038/s42003-019-0503-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 06/13/2019] [Indexed: 12/27/2022] Open
Abstract
Iodide transport and storage in the thyroid follicles is crucial for thyroid hormone synthesis. Pendrin, the iodide exporter that transports iodide to thyroid follicles, is responsible for Pendred syndrome, a disorder characterized by congenital hypothyroidism and hearing loss. However, thyroid hormone levels are basically normal in patients with Pendred syndrome, indicating the presence of another unknown iodide transporter. Here, we show that SLC26A7 is a novel iodide transporter in the thyroid. We observe that SLC26A7 is specifically expressed in normal thyroid tissues and demonstrate its function in iodide transport. Using whole-exome sequencing, we also find a homozygous nonsense mutation in SLC26A7 (c.1498 C > T; p.Gln500Ter) in two siblings with congenital goitrous hypothyroidism. The mutated SLC26A7 protein shows an abnormal cytoplasmic localisation and lacks the iodide transport function. These results reveal that SLC26A7 functions as a novel iodide transporter in the thyroid and its dysfunction affects thyroid hormonogenesis in humans and causes congenital goitrous hypothyroidism.
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Affiliation(s)
- Jun Ishii
- Department of Pathology, Kyorin University School of Medicine, Tokyo, Japan
- Department of Pathology, Dokkyo Medical University, Tochigi, Japan
| | - Atsushi Suzuki
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Toru Kimura
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Michihiro Tateyama
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Tatsushi Tanaka
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Takuya Yazawa
- Department of Pathology, Dokkyo Medical University, Tochigi, Japan
| | - Yu Arimasu
- Department of Pathology, Kyorin University School of Medicine, Tokyo, Japan
| | - I-Shan Chen
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Kohei Aoyama
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Yoshihiro Kubo
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Shinji Saitoh
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Haruo Mizuno
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
- Department of Pediatrics, International University of Health and Welfare, School of Medicine, Narita, Japan
| | - Hiroshi Kamma
- Department of Pathology, Kyorin University School of Medicine, Tokyo, Japan
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Zhu GJ, Shi LS, Zhou H, Yang Y, Chen J, Gao X. A novel compound heterozygous mutation of SLC26A4 in two Chinese families with nonsyndromic hearing loss and enlarged vestibular aqueducts. Mol Med Rep 2017; 16:9011-9016. [PMID: 28990112 DOI: 10.3892/mmr.2017.7690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 08/10/2017] [Indexed: 11/06/2022] Open
Abstract
Enlarged vestibular aqueduct (EVA)‑associated hearing loss is frequently detected in individuals carrying the SLC26A4 mutation in the Chinese population. The present study aimed to identify the causative SLC26A4 coding mutations in a patient group with nonsyndromic hearing loss (NSHL) and EVA. Genomic DNA was extracted from blood samples obtained from 52 NSHL patients with EVA and from 60 normal controls. The mutation analysis for 20 coding exons of SLC26A4 was performed by direct sequencing. The results of the mutational analysis showed that there were two probands from two separate families suffering from bilateral sensorineural hearing loss with EVA, carrying the same novel compound heterozygous mutation of SLC26A4 (c.1644_1645insA and c.2168A>G). Other members of the two families had heterozygous mono‑allelic mutations with normal hearing. However, neither of these mutations were detected in the 60 normal controls. These results are the first, to the best of our knowledge, to link the compound heterozygote mutation, c.1644_1645insA and c.2168A>G, in the SLC26A4 gene to NSHL patients with EVA. The two mutations identified in the present study were located in the anti‑sigma factor antagonist domain, the core region for plasma membrane targeting of anion transporters, which suggested that the reduced or complete loss of SLC26A4 function was the direct cause of hearing loss in the two patients. These results provide a foundation for further elucidating the genetic factors responsible for EVA‑associated NSHL.
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Affiliation(s)
- Guang-Jie Zhu
- Department of Otorhinolaryngology, Head and Neck Surgery, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Lu-Sen Shi
- Department of Otorhinolaryngology, Head and Neck Surgery, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Han Zhou
- Department of Otorhinolaryngology, Head and Neck Surgery, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Ye Yang
- Department of Otorhinolaryngology, Head and Neck Surgery, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Jie Chen
- Department of Otorhinolaryngology, Head and Neck Surgery, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Xia Gao
- Department of Otorhinolaryngology, Head and Neck Surgery, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
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Abstract
Pendred syndrome is an autosomal recessive disorder that is classically defined by the combination of sensorineural deafness/hearing impairment, goiter, and an abnormal organification of iodide with or without hypothyroidism. The hallmark of the syndrome is the impaired hearing, which is associated with inner ear malformations such as an enlarged vestibular aqueduct (EVA). The thyroid phenotype is variable and may be modified by the nutritional iodine intake. Pendred syndrome is caused by biallelic mutations in the SLC26A4/PDS gene, which encodes the multifunctional anion exchanger pendrin. Pendrin has affinity for chloride, iodide, and bicarbonate, among other anions. In the inner ear, pendrin functions as a chloride/bicarbonate exchanger that is essential for maintaining the composition and the potential of the endolymph. In the thyroid, pendrin is expressed at the apical membrane of thyroid cells facing the follicular lumen. Functional studies have demonstrated that pendrin can mediate iodide efflux in heterologous cells. This, together with the thyroid phenotype observed in humans (goiter, impaired iodine organification) suggests that pendrin could be involved in iodide efflux into the lumen, one of the steps required for thyroid hormone synthesis. Iodide efflux can, however, also occur in the absence of pendrin suggesting that other exchangers or channels are involved. It has been suggested that Anoctamin 1 (ANO1/TMEM16A), a calcium-activated anion channel, which is also expressed at the apical membrane of thyrocytes, could participate in mediating apical efflux. In the kidney, pendrin is involved in bicarbonate secretion and chloride reabsorption. While there is no renal phenotype under basal conditions, severe metabolic alkalosis has been reported in Pendred syndrome patients exposed to an increased alkali load. This review provides an overview on the clinical spectrum of Pendred syndrome, the functional data on pendrin with a focus on its potential role in the thyroid, as well as the controversy surrounding the relative physiological roles of pendrin and anoctamin.
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Affiliation(s)
- Jean-Louis Wémeau
- Université de Lille 2, Centre Hospitalier Régional Universitaire de Lille, Clinique Endocrinologique Marc-Linquette, 59037 Lille, France.
| | - Peter Kopp
- Northwestern University, Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Tarry 15, 303 East Chicago Avenue, Chicago, IL 60611, USA.
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8
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Sagong B, Baek JI, Lee KY, Kim UK. A Novel Frameshift Mutation of SLC26A4 in a Korean Family With Nonsyndromic Hearing Loss and Enlarged Vestibular Aqueduct. Clin Exp Otorhinolaryngol 2016; 10:50-55. [PMID: 27384033 PMCID: PMC5327591 DOI: 10.21053/ceo.2016.00430] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 05/22/2016] [Accepted: 05/26/2016] [Indexed: 11/23/2022] Open
Abstract
Objectives We aimed to identify the causative mutation for siblings in a Korean family with nonsyndromic hearing loss (HL) and enlarged vestibular aqueduct (EVA). The siblings were a 19-year-old female with bilateral profound HL and an 11-year-old male with bilateral moderately severe HL. Methods We extracted genomic DNA from blood samples of the siblings with HL, their parents, and 100 controls. We performed mutation analysis for SLC26A4 using direct sequencing. Results The two siblings were compound heterozygotes with the novel mutation p.I713LfsX8 and the previously described mutation p.H723R. Their parents had heterozygous mono-allelic mutations. Father had p.I713LfsX8 mutation as heterozygous, and mother had p.H723R mutation as heterozygous. However, novel mutation p.I713LfsX8 was not detected in 100 unrelated controls. Conclusion Both mutations identified in this study were located in the sulfate transporter and anti-sigma factor antagonist domain, the core region for membrane targeting of SulP/SLC26 anion transporters, which strongly suggests that failure in membrane trafficking by SLC26A4 is a direct cause of HL in this family. Our study could therefore provide a foundation for further investigations elucidating the SLC26A4-related mechanisms of HL.
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Affiliation(s)
- Borum Sagong
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, Korea
| | - Jeong-In Baek
- Department of Aroma Applied Industry, College of Herbal Bio-Industry, Daegu Haany University, Gyeongsan, Korea
| | - Kyu-Yup Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Kyungpook National University School of Medicine, Daegu, Korea
| | - Un-Kyung Kim
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, Korea.,School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Korea
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9
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Silveira JC, Kopp PA. Pendrin and anoctamin as mediators of apical iodide efflux in thyroid cells. Curr Opin Endocrinol Diabetes Obes 2015; 22:374-80. [PMID: 26313899 DOI: 10.1097/med.0000000000000188] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
PURPOSE OF REVIEW Thyroid hormones are essential for normal development, growth, and metabolism. Their synthesis occurs in thyroid follicles and requires an adequate iodide supply and a sequence of regulated biochemical steps. The uptake of iodide into thyrocytes is well characterized, but its efflux at the apical membrane is poorly understood. This review discusses potential mechanisms underlying iodide efflux with emphasis on recent developments and controversies. RECENT FINDINGS The functional characterization of pendrin (PDS/SLC26A4), a multifunctional anion exchanger, suggested that it could be involved in mediating iodide efflux. This is supported by the phenotype of patients with Pendred syndrome (deafness, goiter, partial iodide organification defect), which is caused by biallelic mutations in the SLC26A4 gene, as well as functional studies. However, apical iodide efflux is also possible in the absence of pendrin, implicating the presence of at least another channel. Recently, Anoctamin 1 (TMEM16A), a calcium-activated anion channel has been identified at the apical membrane of thyrocytes and functional studies suggest that it may play a predominant role in mediating iodide efflux. SUMMARY Anoctamin and pendrin are two plausible candidates as mediators of apical iodide efflux. Their relative affinity for iodide and their exact physiological role await, however, further characterization.
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Affiliation(s)
- Jamile C Silveira
- aDivision of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA bDepartment of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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10
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Garnett JP, Hickman E, Tunkamnerdthai O, Cuthbert AW, Gray MA. Protein phosphatase 1 coordinates CFTR-dependent airway epithelial HCO3- secretion by reciprocal regulation of apical and basolateral membrane Cl(-)-HCO3- exchangers. Br J Pharmacol 2015; 168:1946-60. [PMID: 23215877 DOI: 10.1111/bph.12085] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 11/14/2012] [Accepted: 12/01/2012] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE Our recent studies on human airway serous-like Calu-3 cells showed that cAMP agonists stimulated a HCO3(-) rich secretion containing up to 80 mM HCO3(-). This alkaline secretion relied on a coordinated switch in the activity of distinct Cl(-)-HCO3(-) anion exchangers (AE) located at different regions of the cell. At the apical membrane, cAMP agonists activated the electroneutral AE pendrin (SLC26A4), together with cystic fibrosis transmembrane conductance regulator (CFTR), while at the basolateral membrane the agonists inhibited AE2 (SLC4A2). However, the underlying mechanism(s) that orchestrates this cAMP-dependent switch in AE activity has not been elucidated. EXPERIMENTAL APPROACH Apical and basolateral Cl(-)-HCO3(-) exchange was assessed by measuring Cl(-)-dependent changes in intracellular pH (pH(i)). KEY RESULTS We show that protein phosphatase 1 (PP1), together with CFTR, play central roles in this reciprocal regulation of AE activity. Activation of pendrin by cAMP agonists, but not inhibition of the basolateral exchanger, was protein kinase A-dependent. Knocking down CFTR expression, or blocking its activity with GlyH-101, led to incomplete inhibition of the basolateral AE by cAMP, supporting a role for CFTR in this process. Addition of the PP1/2A inhibitor, okadaic acid, but not the PP2A specific inhibitor fostreicin, mimicked the effect of cAMP stimulation. Furthermore, okadaic acid-treated Calu-3 monolayers produced a more alkaline fluid than untreated cells, which was comparable with that produced by cAMP stimulation. CONCLUSIONS AND IMPLICATIONS These results identify PP1 as a novel regulator of AE activity which, in concert with CFTR, coordinates events at both apical and basolateral membranes, crucial for efficient HCO3(-) secretion from Calu-3 cells.
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Affiliation(s)
- James P Garnett
- Institute for Cell & Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
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11
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Atrophic thyroid follicles and inner ear defects reminiscent of cochlear hypothyroidism in Slc26a4-related deafness. Mamm Genome 2014; 25:304-16. [PMID: 24760582 DOI: 10.1007/s00335-014-9515-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 04/03/2014] [Indexed: 01/10/2023]
Abstract
Thyroid hormone is essential for inner ear development and is required for auditory system maturation. Human mutations in SLC26A4 lead to a syndromic form of deafness with enlargement of the thyroid gland (Pendred syndrome) and non-syndromic deafness (DFNB4). We describe mice with an Slc26a4 mutation, Slc26a4 (loop/loop) , which are profoundly deaf but show a normal sized thyroid gland, mimicking non-syndromic clinical signs. Histological analysis of the thyroid gland revealed defective morphology, with a majority of atrophic microfollicles, while measurable thyroid hormone in blood serum was within the normal range. Characterization of the inner ear showed a spectrum of morphological and molecular defects consistent with inner ear pathology, as seen in hypothyroidism or disrupted thyroid hormone action. The pathological inner ear hallmarks included thicker tectorial membrane with reduced β-tectorin protein expression, the absence of BK channel expression of inner hair cells, and reduced inner ear bone calcification. Our study demonstrates that deafness in Slc26a4 (loop/loop) mice correlates with thyroid pathology, postulating that sub-clinical thyroid morphological defects may be present in some DFNB4 individuals with a normal sized thyroid gland. We propose that insufficient availability of thyroid hormone during inner ear development plays an important role in the mechanism underlying deafness as a result of SLC26A4 mutations.
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Yao G, Chen D, Wang H, Li S, Zhang J, Feng Z, Guo L, Yang Z, Yang S, Sun C, Zhang X, Ma D. Novel mutations of SLC26A4 in Chinese patients with nonsyndromic hearing loss. Acta Otolaryngol 2013; 133:833-41. [PMID: 23638949 DOI: 10.3109/00016489.2013.777160] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSIONS This study demonstrated high prevalence of GJB2, SLC26A4, and mtDNA A1555G mutations in Chinese patients with nonsyndromic hearing loss and discovered eight novel mutations in SLC26A4. Most of these novel mutations were predicted pathogenic variants. OBJECTIVES Nonsyndromic hearing loss is the most common neurosensory deafness where the majority of patients have highly diversified genetic defects. This study aimed to define the genetic profile of deafness in a Chinese population with potential to discover novel mutations. METHODS A total of 227 segregating deaf students and 200 individuals with normal hearing were enrolled. With the Sanger sequencing chemistry, direct sequencing was performed on entire coding regions of GJB2, GJB3, SLC26A4, and mtDNA m.C1494T and m.A1555G. RESULTS Direct sequencing analysis revealed that 53 (23.35%) of 227 patients carried at least 1 mutant allele in GJB2, 40 (17.62%) patients in SLC26A4, 5 (2.20%) patients in mtDNA A1555G, and 1 (0.44%) patient in mtDNA C1494T mutations. Four patients carried three unclassified mutations in GJB3 genes. Overall 38 mutant variants were detected in this cohort of patients, including 8 novel mutations in SLC26A4. The eight novel variants were six missense substitutions (p.V163L, p.G222S, p.A456D, p.N457I, p.C466Y, p.F667L), one nonsense mutation (p.W472X), and one frameshift (p.Asn612Ilefs×23).
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Affiliation(s)
- Gendong Yao
- Department of Laboratory Medicine, Central Hospital of Handan City, Hebei, China.
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13
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Yao G, Li S, Chen D, Wang H, Zhang J, Feng Z, Guo L, Yang Z, Yang S, Sun C, Zhang X, Ma D. Compound heterozygous mutations of SLC26A4 in 4 Chinese families with enlarged vestibular aqueduct. Int J Pediatr Otorhinolaryngol 2013; 77:544-9. [PMID: 23385134 DOI: 10.1016/j.ijporl.2013.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 01/04/2013] [Accepted: 01/05/2013] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Enlarged vestibular aqueduct is the most common inner ear malformation in individuals with sensorineural hearing loss. Mutations in SLC26A4 can cause non-syndromic EVA. To date, more than 170 SLC26A4 mutations have been described. The aim of the present study was to detect and report genetic causes of four unrelated Chinese families with hearing loss. METHODS We evaluated 4 families presenting bilateral enlarged vestibular aqueducts and describe the clinical and molecular characteristics of 5 patients. RESULTS The SLC26A4 gene was sequenced in 23 members of these 4 Chinese families with EVA, and the patients were found to carry 4 compound heterozygous mutations, p.G197R and p.S391R, IVS7-2A>G, p.I188T and c.1746 del G, p.V659L and p.T410M, and p.T94I and p.G197R, none of which have been reported previously. CONCLUSIONS These results emphasize the necessity of considering the complete DNA sequencing of the SLC26A4 gene in molecular diagnosis of deafness, especially when phenotypes such as congenital, invariable, and progressive hearing loss with EVA are present.
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Affiliation(s)
- Gendong Yao
- Central Hospital of Handan, 056001 Hebei, China.
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Pelzl L, Pakladok T, Pathare G, Fakhri H, Michael D, Wagner CA, Paulmichl M, Lang F. DOCA sensitive pendrin expression in kidney, heart, lung and thyroid tissues. Cell Physiol Biochem 2012; 30:1491-501. [PMID: 23235354 DOI: 10.1159/000343337] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2012] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND/AIMS Pendrin (SLC26A4), a transporter accomplishing anion exchange, is expressed in inner ear, thyroid gland, kidneys, lung, liver and heart. Loss or reduction of function mutations of SLC26A4 underlie Pendred syndrome, a disorder invariably leading to hearing loss with enlarged vestibular aqueducts and in some patients to hypothyroidism and goiter. Renal pendrin expression is up-regulated by mineralocorticoids such as aldosterone or deoxycorticosterone (DOCA). Little is known about the impact of mineralocorticoids on pendrin expression in extrarenal tissues. METHODS The present study utilized RT-qPCR and Western blotting to quantify the transcript levels and protein abundance of Slc26a4 in murine kidney, thyroid, heart and lung prior to and following subcutaneous administration of 100 mg/kg DOCA. RESULTS Slc26a4 transcript levels as compared to Gapdh transcript levels were significantly increased by DOCA treatment in kidney, heart, lung and thyroid. Accordingly pendrin protein expression was again significantly increased by DOCA treatment in kidney, heart, lung and thyroid. CONCLUSION The observations reveal mineralocorticoid sensitivity of pendrin expression in kidney, heart, thyroid and lung.
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Affiliation(s)
- Lisann Pelzl
- Department of Physiology, University of Tuebingen, Tuebingen, Germany
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15
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A novel insertion-induced frameshift mutation of the SLC26A4 gene in a Korean family with Pendred syndrome. Gene 2012; 508:135-9. [DOI: 10.1016/j.gene.2012.07.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 07/11/2012] [Accepted: 07/18/2012] [Indexed: 11/18/2022]
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Busi M, Castiglione A, Taddei Masieri M, Ravani A, Guaran V, Astolfi L, Trevisi P, Ferlini A, Martini A. Novel mutations in the SLC26A4 gene. Int J Pediatr Otorhinolaryngol 2012; 76:1249-54. [PMID: 22717225 DOI: 10.1016/j.ijporl.2012.05.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 05/16/2012] [Accepted: 05/17/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVES Mutations in the SLC26A4 gene (7q22.3-7q31.1) are considered one of the most common causes of genetic hearing loss. There are two clinical forms related to these mutations: syndromic and non-syndromic deafness. The first one is named Pendred Syndrome (PS) when deafness is associated with thyroid goiter; the second is called DFNB4, when no other symptoms are present. Both are transmitted as an autosomal recessive trait, but simple heterozygotes can develop both forms of deafness. Actually it is thought that Pendred Syndrome occurs when both alleles of SLC26A4 gene are mutated; DFNB4 seems due to monoallelic mutations. PS and DFNB4 can be associated with inner ear malformations. In most of the cases (around 80%), these consist in Enlarged Vestibular Aqueduct (EVA). EVA can also be present without SLC26A4 mutations. Understanding the role of new SLC26A4 variants should facilitate clinical assessment, as well as diagnostic and therapeutic approaches. This investigation aims to detect and report genetic causes of two unrelated Italian boys with hearing loss. METHODS Patients and family members underwent clinical, audiological and genetic evaluations. To identify genetic mutations, DNA sequencing of SLC26A4 gene (including all 21 exons, exon-intron boundaries and promoter region) was carried out. RESULTS Both probands were affected by congenital, progressive and fluctuating mixed hearing loss. Temporal bone imaging revealed a bilateral EVA with no other abnormalities in both cases. Probands were heterozygotes for previously undescribed mutations in the SLC26A4 gene: R409H/IVS2+1delG (proband 1) and L236P/K590X (proband 2). No other mutations were detected in GJB2, GJB6 genes or mitochondrial DNA (mit-DNA). CONCLUSIONS The IVS2+1delG and K590X mutations have not yet been described in literature but there is some evidence to suggest that they have a pathological role. The results underlined the importance of considering the complete DNA sequencing of the SLC26A4 gene for differential molecular diagnosis of deafness, especially in those patients affected by congenital, progressive and fluctuating mixed hearing loss with bilateral EVA.
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Affiliation(s)
- Micol Busi
- Audiology Department - C.so Giovecca 203, 44121, University of Ferrara, Italy.
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Azroyan A, Morla L, Crambert G, Laghmani K, Ramakrishnan S, Edwards A, Doucet A. Regulation of pendrin by cAMP: possible involvement in β-adrenergic-dependent NaCl retention. Am J Physiol Renal Physiol 2012; 302:F1180-7. [PMID: 22262479 DOI: 10.1152/ajprenal.00403.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The sodium-independent anion exchanger pendrin is expressed in several tissues including the kidney cortical collecting duct (CCD), where it acts as a chloride/bicarbonate exchanger and has been shown to participate in the regulation of acid-base homeostasis and blood pressure. The renal sympathetic nervous system is known to play a key role in the development of salt-induced hypertension. This study aimed to determine whether pendrin may partly mediate the effects of β adrenergic receptors (β-AR) on renal salt handling. We investigated the regulation of pendrin activity by the cAMP/protein kinase A (PKA) signaling pathway, both in vitro in opossum kidney proximal (OKP) cells stably transfected with pendrin cDNA and ex vivo in isolated microperfused CCDs stimulated by isoproterenol, a β-AR agonist. We found that stimulation of the cAMP/PKA pathway in OKP cells increased the amount of pendrin at the cell surface as well as its transport activity. These effects stemmed from increased exocytosis of pendrin and were associated with its phosphorylation. Furthermore, cAMP effects on the membrane expression and activity of pendrin were abolished by mutating the serine 49 located in the intracellular N-terminal domain of pendrin. Finally, we showed that isoproterenol increases pendrin trafficking to the apical membrane as well as the reabsorption of both Cl(-) and Na(+) in microperfused CCDs. All together, our results strongly suggest that pendrin activation by the cAMP/PKA pathway underlies isoproterenol-induced stimulation of NaCl reabsorption in the kidney collecting duct, a mechanism likely involved in the sodium-retaining effect of β-adrenergic agonists.
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Affiliation(s)
- Anie Azroyan
- UPMC Université Paris 06, Université Paris 05, INSERM, UMRS872, and CNRS ERL7226, Laboratoire de Génomique, Physiologie et Physiopathologie Rénales, Centre de Recherche des Cordeliers, Paris, France
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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: 3] [Impact Index Per Article: 0.2] [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, Kopp P. Controversies Concerning the Role of Pendrin as an Apical Iodide Transporter in Thyroid Follicular Cells. Cell Physiol Biochem 2011; 28:485-90. [DOI: 10.1159/000335103] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2011] [Indexed: 11/19/2022] Open
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