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Remigante A, Spinelli S, Zuccolini P, Gavazzo P, Marino A, Pusch M, Morabito R, Dossena S. Melatonin protects Kir2.1 function in an oxidative stress-related model of aging neuroglia. Biofactors 2024; 50:523-541. [PMID: 38095328 DOI: 10.1002/biof.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 11/01/2023] [Indexed: 06/15/2024]
Abstract
Melatonin is a pleiotropic biofactor and an effective antioxidant and free radical scavenger and, as such, can be protective in oxidative stress-related brain conditions including epilepsy and aging. To test the potential protective effect of melatonin on brain homeostasis and identify the corresponding molecular targets, we established a new model of oxidative stress-related aging neuroglia represented by U-87 MG cells exposed to D-galactose (D-Gal). This model was characterized by a substantial elevation of markers of oxidative stress, lipid peroxidation, and protein oxidation. The function of the inward rectifying K+ channel Kir2.1, which was identified as the main Kir channel endogenously expressed in these cells, was dramatically impaired. Kir2.1 was unlikely a direct target of oxidative stress, but the loss of function resulted from a reduction of protein abundance, with no alterations in transcript levels and trafficking to the cell surface. Importantly, melatonin reverted these changes. All findings, including the melatonin antioxidant effect, were reproduced in heterologous expression systems. We conclude that the glial Kir2.1 can be a target of oxidative stress and further suggest that inhibition of its function might alter the extracellular K+ buffering in the brain, therefore contributing to neuronal hyperexcitability and epileptogenesis during aging. Melatonin can play a protective role in this context.
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Affiliation(s)
- Alessia Remigante
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Sara Spinelli
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Paolo Zuccolini
- Institute of Biophysics, National Research Council, Genova, Italy
| | - Paola Gavazzo
- Institute of Biophysics, National Research Council, Genova, Italy
| | - Angela Marino
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Michael Pusch
- Institute of Biophysics, National Research Council, Genova, Italy
| | - Rossana Morabito
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
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Takahashi S, Kojima T, Wasano K, Homma K. Functional Studies of Deafness-Associated Pendrin and Prestin Variants. Int J Mol Sci 2024; 25:2759. [PMID: 38474007 PMCID: PMC10931795 DOI: 10.3390/ijms25052759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 02/21/2024] [Accepted: 02/23/2024] [Indexed: 03/14/2024] Open
Abstract
Pendrin and prestin are evolutionary-conserved membrane proteins that are essential for normal hearing. Dysfunction of these proteins results in hearing loss in humans, and numerous deafness-associated pendrin and prestin variants have been identified in patients. However, the pathogenic impacts of many of these variants are ambiguous. Here, we report results from our ongoing efforts to experimentally characterize pendrin and prestin variants using in vitro functional assays. With previously established fluorometric anion transport assays, we determined that many of the pendrin variants identified on transmembrane (TM) 10, which contains the essential anion binding site, and on the neighboring TM9 within the core domain resulted in impaired anion transport activity. We also determined the range of functional impairment in three deafness-associated prestin variants by measuring nonlinear capacitance (NLC), a proxy for motor function. Using the results from our functional analyses, we also evaluated the performance of AlphaMissense (AM), a computational tool for predicting the pathogenicity of missense variants. AM prediction scores correlated well with our experimental results; however, some variants were misclassified, underscoring the necessity of experimentally assessing the effects of variants. Together, our experimental efforts provide invaluable information regarding the pathogenicity of deafness-associated pendrin and prestin variants.
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Affiliation(s)
- Satoe Takahashi
- Department of Otolaryngology—Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Takashi Kojima
- Department of Otolaryngology—Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Department of Otolaryngology, Head and Neck Surgery, National Hospital Organization Tochigi Medical Center, Tochigi 320-0057, Japan
| | - Koichiro Wasano
- Department of Otolaryngology—Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Department of Otolaryngology, Head and Neck Surgery, Tokai University School of Medicine, Isehara 259-1193, Japan
| | - Kazuaki Homma
- Department of Otolaryngology—Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL 60208, USA
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3
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Takahashi S, Kojima T, Wasano K, Homma K. Functional studies of deafness-associated pendrin and prestin variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.23.576877. [PMID: 38328051 PMCID: PMC10849616 DOI: 10.1101/2024.01.23.576877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Pendrin and prestin are evolutionary conserved membrane proteins that are essential for normal hearing. Pendrin is an anion transporter required for normal development and maintenance of ion homeostasis in the inner ear, while prestin is a voltage-dependent motor responsible for cochlear amplification essential for high sensitivity and frequency selectivity of mammalian hearing. Dysfunction of these proteins result in hearing loss in humans, and numerous deafness-associated pendrin and prestin variants have been identified in patients. However, the pathogenic impacts of many of these variants are ambiguous. Here we report results from our ongoing efforts in experimentally characterizing pendrin and prestin variants using in vitro functional assays, providing invaluable information regarding their pathogenicity.
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Liu Q, Zhang X, Huang H, Chen Y, Wang F, Hao A, Zhan W, Mao Q, Hu Y, Han L, Sun Y, Zhang M, Liu Z, Li GL, Zhang W, Shu Y, Sun L, Chen Z. Asymmetric pendrin homodimer reveals its molecular mechanism as anion exchanger. Nat Commun 2023; 14:3012. [PMID: 37230976 DOI: 10.1038/s41467-023-38303-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 04/23/2023] [Indexed: 05/27/2023] Open
Abstract
Pendrin (SLC26A4) is an anion exchanger expressed in the apical membranes of selected epithelia. Pendrin ablation causes Pendred syndrome, a genetic disorder associated with sensorineural hearing loss, hypothyroid goiter, and reduced blood pressure. However its molecular structure has remained unknown, limiting our understanding of the structural basis of transport. Here, we determine the cryo-electron microscopy structures of mouse pendrin with symmetric and asymmetric homodimer conformations. The asymmetric homodimer consists of one inward-facing protomer and the other outward-facing protomer, representing coincident uptake and secretion- a unique state of pendrin as an electroneutral exchanger. The multiple conformations presented here provide an inverted alternate-access mechanism for anion exchange. The structural and functional data presented here disclose the properties of an anion exchange cleft and help understand the importance of disease-associated variants, which will shed light on the pendrin exchange mechanism.
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Affiliation(s)
- Qianying Liu
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Xiang Zhang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Hui Huang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yuxin Chen
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Fang Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Aihua Hao
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Wuqiang Zhan
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Qiyu Mao
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yuxia Hu
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Lin Han
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yifang Sun
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Meng Zhang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Zhimin Liu
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Geng-Lin Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Weijia Zhang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yilai Shu
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China.
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China.
- Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
| | - Lei Sun
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai, 200032, China.
- Shanghai Key Laboratory of Medical Epigenetics, Shanghai, 200032, China.
| | - Zhenguo Chen
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai, 200032, China.
- Shanghai Key Laboratory of Medical Epigenetics, Shanghai, 200032, China.
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Silva VAR, Pauna HF, Lavinsky J, Hyppolito MA, Vianna MF, Leal M, Massuda ET, Hamerschmidt R, Bahmad F, Cal RV, Sampaio ALL, Felix F, Chone CT, Castilho AM. Task force Guideline of Brazilian Society of Otology ‒ hearing loss in children - Part I ‒ Evaluation. Braz J Otorhinolaryngol 2022; 89:159-189. [PMID: 36529647 PMCID: PMC9874360 DOI: 10.1016/j.bjorl.2022.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 11/14/2022] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES To provide an overview of the main evidence-based recommendations for the diagnosis of hearing loss in children and adolescents aged 0 to 18 years. METHODS Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on childhood hearing loss were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions. RESULTS The evaluation and diagnosis of hearing loss: universal newborn hearing screening, laboratory testing, congenital infections (especially cytomegalovirus), genetic testing and main syndromes, radiologic imaging studies, vestibular assessment of children with hearing loss, auditory neuropathy spectrum disorder, autism spectrum disorder, and noise-induced hearing loss. CONCLUSIONS Every child with suspected hearing loss has the right to diagnosis and appropriate treatment if necessary. This task force considers 5 essential rights: (1) Otolaryngologist consultation; (2) Speech assessment and therapy; (3) Diagnostic tests; (4) Treatment; (5) Ophthalmologist consultation.
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Affiliation(s)
- Vagner Antonio Rodrigues Silva
- Universidade Estadual de Campinas (Unicamp), Faculdade de Ciências Médicas, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Campinas, SP, Brazil.
| | - Henrique Furlan Pauna
- Hospital Universitário Cajuru, Departamento de Otorrinolaringologia, Curitiba, PR, Brazil
| | - Joel Lavinsky
- Universidade Federal do Rio Grande do Sul (UFRGS), Departamento de Cirurgia, Porto Alegre, RS, Brazil
| | - Miguel Angelo Hyppolito
- Universidade de São Paulo (USP), Faculdade de Medicina de Ribeirão Preto, Departamento de Oftalmologia, Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Ribeirão Preto, SP, Brazil
| | - Melissa Ferreira Vianna
- Irmandade Santa Casa de Misericórdia de São Paulo, Departamento de Otorrinolaringologia, São Paulo, SP, Brazil
| | - Mariana Leal
- Universidade Federal de Pernambuco (UFPE), Departamento de Cirurgia, Recife, PE, Brazil
| | - Eduardo Tanaka Massuda
- Universidade de São Paulo (USP), Faculdade de Medicina de Ribeirão Preto, Departamento de Oftalmologia, Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Ribeirão Preto, SP, Brazil
| | - Rogério Hamerschmidt
- Universidade Federal do Paraná (UFPR), Hospital de Clínicas, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Curitiba, PR, Brazil
| | - Fayez Bahmad
- Universidade de Brasília (UnB), Programa de Pós-Graduação em Ciências da Saúde, Brasília, DF, Brazil; Instituto Brasiliense de Otorrinolaringologia (IBO), Brasília, DF, Brazil
| | - Renato Valério Cal
- Centro Universitário do Estado do Pará (CESUPA), Departamento de Otorrinolaringologia, Belém, PA, Brazil
| | - André Luiz Lopes Sampaio
- Universidade de Brasília (UnB), Faculdade de Medicina, Laboratório de Ensino e Pesquisa em Otorrinolaringologia, Brasília, DF, Brazil
| | - Felippe Felix
- Universidade Federal do Rio de Janeiro (UFRJ), Hospital Universitário Clementino Fraga Filho (HUCFF), Departamento de Otorrinolaringologia, Rio de Janeiro, RJ, Brazil
| | - Carlos Takahiro Chone
- Universidade Estadual de Campinas (Unicamp), Faculdade de Ciências Médicas, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Campinas, SP, Brazil
| | - Arthur Menino Castilho
- Universidade Estadual de Campinas (Unicamp), Faculdade de Ciências Médicas, Departamento de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Campinas, SP, Brazil
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6
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Bernardinelli E, Roesch S, Simoni E, Marino A, Rasp G, Astolfi L, Sarikas A, Dossena S. Novel POU3F4 variants identified in patients with inner ear malformations exhibit aberrant cellular distribution and lack of SLC6A20 transcriptional upregulation. Front Mol Neurosci 2022; 15:999833. [PMID: 36245926 PMCID: PMC9558712 DOI: 10.3389/fnmol.2022.999833] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/13/2022] [Indexed: 11/14/2022] Open
Abstract
Hearing loss (HL) is the most common sensory defect and affects 450 million people worldwide in a disabling form. Pathogenic sequence alterations in the POU3F4 gene, which encodes a transcription factor, are causative of the most common type of X-linked deafness (X-linked deafness type 3, DFN3, DFNX2). POU3F4-related deafness is characterized by a typical inner ear malformation, namely an incomplete partition of the cochlea type 3 (IP3), with or without an enlargement of the vestibular aqueduct (EVA). The pathomechanism underlying POU3F4-related deafness and the corresponding transcriptional targets are largely uncharacterized. Two male patients belonging to a Caucasian cohort with HL and EVA who presented with an IP3 were submitted to genetic analysis. Two novel sequence variants in POU3F4 were identified by Sanger sequencing. In cell-based assays, the corresponding protein variants (p.S74Afs*8 and p.C327*) showed an aberrant expression and subcellular distribution and lack of transcriptional activity. These two protein variants failed to upregulate the transcript levels of the amino acid transporter gene SLC6A20, which was identified as a novel transcriptional target of POU3F4 by RNA sequencing and RT-qPCR. Accordingly, POU3F4 silencing by siRNA resulted in downregulation of SLC6A20 in mouse embryonic fibroblasts. Moreover, we showed for the first time that SLC6A20 is expressed in the mouse cochlea, and co-localized with POU3F4 in the spiral ligament. The findings presented here point to a novel role of amino acid transporters in the inner ear and pave the way for mechanistic studies of POU3F4-related HL.
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Affiliation(s)
- Emanuele Bernardinelli
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Sebastian Roesch
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, Salzburg, Austria
| | - Edi Simoni
- Bioacoustic Research Laboratory, Department of Neuroscience, Biomedical Campus Pietro d’Abano, University of Padua, Padua, Italy
| | - Angela Marino
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Messina, Italy
| | - Gerd Rasp
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, Salzburg, Austria
| | - Laura Astolfi
- Bioacoustic Research Laboratory, Department of Neuroscience, Biomedical Campus Pietro d’Abano, University of Padua, Padua, Italy
- Interdepartmental Research Center of International Auditory Processing Project in Venice (I-APPROVE), Department of Neurosciences, University of Padova, Santi Giovanni e Paolo Hospital, ULSS3, Venice, Italy
| | - Antonio Sarikas
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
- *Correspondence: Antonio Sarikas,
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
- Silvia Dossena,
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Matulevičius A, Bernardinelli E, Brownstein Z, Roesch S, Avraham KB, Dossena S. Molecular Features of SLC26A4 Common Variant p.L117F. J Clin Med 2022; 11:5549. [PMID: 36233414 PMCID: PMC9570580 DOI: 10.3390/jcm11195549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 11/16/2022] Open
Abstract
The SLC26A4 gene, which encodes the anion exchanger pendrin, is involved in determining syndromic (Pendred syndrome) and non-syndromic (DFNB4) autosomal recessive hearing loss. SLC26A4 c.349C>T, p.L117F is a relatively common allele in the Ashkenazi Jewish community, where its minor allele frequency is increased compared to other populations. Although segregation and allelic data support the pathogenicity of this variant, former functional tests showed characteristics that were indistinguishable from those of the wild-type protein. Here, we applied a triad of cell-based assays, i.e., measurement of the ion transport activity by a fluorometric method, determination of the subcellular localization by confocal microscopy, and assessment of protein expression levels, to conclusively assign or exclude the pathogenicity of SLC26A4 p.L117F. This protein variant showed a moderate, but significant, reduction in ion transport function, a partial retention in the endoplasmic reticulum, and a strong reduction in expression levels as a consequence of an accelerated degradation by the Ubiquitin Proteasome System, all supporting pathogenicity. The functional and molecular features of human pendrin p.L117F were recapitulated by the mouse ortholog, thus indicating that a mouse carrying this variant might represent a good model of Pendred syndrome/DFNB4.
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Affiliation(s)
- Arnoldas Matulevičius
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Emanuele Bernardinelli
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Zippora Brownstein
- Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Sebastian Roesch
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Karen B. Avraham
- Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020 Salzburg, Austria
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Byun JC, Lee KY, Hwang SK. Atypical Presentation of Enlarged Vestibular Aqueducts Caused by SLC26A4 Variants. CHILDREN 2022; 9:children9020165. [PMID: 35204885 PMCID: PMC8869968 DOI: 10.3390/children9020165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 01/16/2022] [Accepted: 01/25/2022] [Indexed: 11/16/2022]
Abstract
Enlarged vestibular aqueduct is the most common inner ear malformation in pediatric patients with sensorineural hearing loss. Here, we report a new presentation of enlarged vestibular aqueduct in a Korean family. The family consists of two parents and five daughters, and the first and second daughters were diagnosed with bilateral enlarged vestibular aqueducts. The third daughter, who showed no signs of hearing deterioration, came to medical attention with incomplete Horner syndrome. Evaluations for localization of Horner syndrome on the patient and Sanger sequencing of SLC26A4 on the family members were performed. Although auditory brainstem response and pure tone audiometry of the third daughter were normal, temporal bone computed tomography demonstrated bilateral enlarged vestibular aqueducts. Sanger sequencing of SLC26A4 revealed compound heterozygous variants c.2168A>G and c.919-2A>G in the first, second, and third daughters. Diagnosis of enlarged vestibular aqueduct is often delayed because the degree of hearing loss can vary, and a considerable phenotypic variability can be shown even in family members with the same SLC26A4 variations. Fluctuations of CSF pressure into the cochlear duct and recurrent microruptures of the endolymphatic membrane could result in damage of sympathetic nerve supplying to the inner ear, which could explain the mechanism of Horner syndrome associated with enlarged vestibular aqueduct.
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Affiliation(s)
- Jun Chul Byun
- Department of Pediatrics, School of Medicine, Keimyung University Dongsan Medical Center, Daegu 42601, Korea;
| | - Kyu-Yup Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine, Kyungpook National University, Daegu 41944, Korea;
| | - Su-Kyeong Hwang
- Department of Pediatrics, School of Medicine, Kyungpook National University, Daegu 41944, Korea
- Correspondence: ; Tel.: +82-53-200-5704; Fax: +82-53-425-6683
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9
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Roesch S, Rasp G, Sarikas A, Dossena S. Genetic Determinants of Non-Syndromic Enlarged Vestibular Aqueduct: A Review. Audiol Res 2021; 11:423-442. [PMID: 34562878 PMCID: PMC8482117 DOI: 10.3390/audiolres11030040] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/02/2021] [Accepted: 08/24/2021] [Indexed: 12/13/2022] Open
Abstract
Hearing loss is the most common sensorial deficit in humans and one of the most common birth defects. In developed countries, at least 60% of cases of hearing loss are of genetic origin and may arise from pathogenic sequence alterations in one of more than 300 genes known to be involved in the hearing function. Hearing loss of genetic origin is frequently associated with inner ear malformations; of these, the most commonly detected is the enlarged vestibular aqueduct (EVA). EVA may be associated to other cochleovestibular malformations, such as cochlear incomplete partitions, and can be found in syndromic as well as non-syndromic forms of hearing loss. Genes that have been linked to non-syndromic EVA are SLC26A4, GJB2, FOXI1, KCNJ10, and POU3F4. SLC26A4 and FOXI1 are also involved in determining syndromic forms of hearing loss with EVA, which are Pendred syndrome and distal renal tubular acidosis with deafness, respectively. In Caucasian cohorts, approximately 50% of cases of non-syndromic EVA are linked to SLC26A4 and a large fraction of patients remain undiagnosed, thus providing a strong imperative to further explore the etiology of this condition.
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Affiliation(s)
- Sebastian Roesch
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, 5020 Salzburg, Austria; (S.R.); (G.R.)
| | - Gerd Rasp
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, 5020 Salzburg, Austria; (S.R.); (G.R.)
| | - Antonio Sarikas
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020 Salzburg, Austria;
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020 Salzburg, Austria;
- Correspondence: ; Tel.: +43-(0)662-2420-80564
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Kınoğlu K, Orhan KS, Kara H, Öztürk O, Polat B, Aydoğan H, Çelik M, Ceviz AB, Güldiken Y. Investigation of DFNB4 SLC26A4 mutation in patients with enlarged vestibular aquaduct. Int J Pediatr Otorhinolaryngol 2020; 138:110379. [PMID: 33152970 DOI: 10.1016/j.ijporl.2020.110379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/02/2020] [Accepted: 09/09/2020] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Mutations of the SLC26A4 gene causing enlarged vestibular aqueduct (EVA) syndrome have not yet been fully elucidated. The study aimed to investigate SLC26A4 mutations in patients with EVA syndrome in the Turkish population. Identifying these mutations may play an essential role in determining the prognosis, follow-up, and management options of these patients. METHODS Whole exome sequencing and/or Sanger sequencing of SLC26A4 in 22 patients with sensorineural hearing loss associated with isolated EVA without inner ear anomalies, and 22 controls were performed. RESULTS Twenty-two patients and 22 control subjects were included in the study. The onset of hearing loss was pre-lingual in 15 patients, and post-lingual in 7. The mean (standard deviation) vestibular aqueduct width of the patients was 3.23 mm (1.28). Twenty SLC26A4 variants, 15 of them unique, were identified in 22 patients. Among them, seven variants were heterozygous, and 13 were homozygous. The variants p.E37X (c.109G > T), p.Y27H (c.79T > C), p.C706Y (c.2117G > A) have not been previously reported. CONCLUSION The detection of rare and previously unreported mutations in our study showed that studies with a larger number of patients with EVA might reveal more role of the SLC26A4 gene. Besides, to understand the etiopathogenesis of the disease, other related genes also should be investigated.
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Affiliation(s)
- Kubilay Kınoğlu
- Istanbul University, Aziz Sancar Institute of Experimental Medicine, Turkey
| | - Kadir Serkan Orhan
- Istanbul University, Istanbul Faculty of Medicine, Department of Otorhinolaryngology
| | - Hakan Kara
- Istanbul University, Istanbul Faculty of Medicine, Department of Otorhinolaryngology.
| | - Oğuz Öztürk
- Istanbul University, Aziz Sancar Institute of Experimental Medicine, Turkey
| | - Beldan Polat
- Istanbul University, Istanbul Faculty of Medicine, Department of Otorhinolaryngology
| | - Hülya Aydoğan
- Istanbul University, Aziz Sancar Institute of Experimental Medicine, Turkey
| | - Mehmet Çelik
- Istanbul University, Istanbul Faculty of Medicine, Department of Otorhinolaryngology
| | - Ayşe Begüm Ceviz
- Istanbul University, Aziz Sancar Institute of Experimental Medicine, Turkey
| | - Yahya Güldiken
- Istanbul University, Istanbul Faculty of Medicine, Department of Otorhinolaryngology
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11
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Malesci R, Russo R, Monzillo C, Laria C, Corvino V, Auletta G, Iolascon A, Franzè A. Bimodal strategy for excellent audiological rehabilitation in a subject with a novel nonsense mutation of the SLC26A4 gene: A case report. Int J Pediatr Otorhinolaryngol 2020; 134:110018. [PMID: 32251972 DOI: 10.1016/j.ijporl.2020.110018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 10/24/2022]
Abstract
Sensorineural hearing loss is a heterogeneous disease caused by mutations in many genes. However, in the presence of enlarged vestibular aqueduct, it is frequently associated with mutations in the solute carrier family 26 member 4 (SLC26A4), a gene causative of a syndromic form (Pendred) as well as a non-syndromic form of hearing loss (DFNB4). We describe a clinical case presenting bilateral sensorineural hearing loss and enlarged vestibular aqueduct in which a novel homozygous SLC26A4 mutation was identified. Despite a late diagnosis of hearing loss, a peculiar rehabilitation therapy strategy was identified that provided excellent results.
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Affiliation(s)
- Rita Malesci
- Institute of Audiology, Dept. of Neurosciences, Reproductive and Odontostomatologic Sciences, University of Naples Federico II, Naples, Italy.
| | - Roberta Russo
- Dept. of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Italy; CEINGE- Advanced Biotechnologies, Naples, Italy.
| | - Carmela Monzillo
- Institute of Audiology, Dept. of Neurosciences, Reproductive and Odontostomatologic Sciences, University of Naples Federico II, Naples, Italy.
| | - Carla Laria
- Institute of Audiology, Dept. of Neurosciences, Reproductive and Odontostomatologic Sciences, University of Naples Federico II, Naples, Italy.
| | - Virginia Corvino
- Institute of Audiology, Dept. of Neurosciences, Reproductive and Odontostomatologic Sciences, University of Naples Federico II, Naples, Italy.
| | - Gennaro Auletta
- Institute of Audiology, Dept. of Neurosciences, Reproductive and Odontostomatologic Sciences, University of Naples Federico II, Naples, Italy.
| | - Achille Iolascon
- Dept. of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Italy; CEINGE- Advanced Biotechnologies, Naples, Italy.
| | - Annamaria Franzè
- Institute of Audiology, Dept. of Neurosciences, Reproductive and Odontostomatologic Sciences, University of Naples Federico II, Naples, Italy; CEINGE- Advanced Biotechnologies, Naples, Italy.
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12
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Targovnik HM, Scheps KG, Rivolta CM. Defects in protein folding in congenital hypothyroidism. Mol Cell Endocrinol 2020; 501:110638. [PMID: 31751626 DOI: 10.1016/j.mce.2019.110638] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/21/2019] [Accepted: 11/01/2019] [Indexed: 12/26/2022]
Abstract
Primary congenital hypothyroidism (CH) is the most common endocrine disease in children and one of the most common preventable causes of both cognitive and motor deficits. CH is a heterogeneous group of thyroid disorders in which inadequate production of thyroid hormone occurs due to defects in proteins involved in the gland organogenesis (dysembryogenesis) or in multiple steps of thyroid hormone biosynthesis (dyshormonogenesis). Dysembryogenesis is associated with genes responsible for the development or growth of thyroid cells: such as NKX2-1, FOXE1, PAX8, NKX2-5, TSHR, TBX1, CDCA8, HOXD3 and HOXB3 resulting in agenesis, hypoplasia or ectopia of thyroid gland. Nevertheless, the etiology of the dysembryogenesis remains unknown for most cases. In contrast, the majority of patients with dyshormonogenesis has been linked to mutations in the SLC5A5, SLC26A4, SLC26A7, TPO, DUOX1, DUOX2, DUOXA1, DUOXA2, IYD or TG genes, which usually originate goiter. About 800 genetic mutations have been reported to cause CH in patients so far, including missense, nonsense, in-frame deletion and splice-site variations. Many of these mutations are implicated in specific domains, cysteine residues or glycosylation sites, affecting the maturation of nascent proteins that go through the secretory pathway. Consequently, misfolded proteins are permanently entrapped in the endoplasmic reticulum (ER) and are translocated to the cytosol for proteasomal degradation by the ER-associated degradation (ERAD) machinery. Despite of all these remarkable advances in the field of the CH pathogenesis, several points on the development of this disease remain to be elucidated. The continuous study of thyroid gene mutations with the application of new technologies will be useful for the understanding of the intrinsic mechanisms related to CH. In this review we summarize the present status of knowledge on the disorders in the protein folding caused by thyroid genes mutations.
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Affiliation(s)
- Héctor M Targovnik
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina.
| | - Karen G Scheps
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Carina M Rivolta
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
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13
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Wasano K, Takahashi S, Rosenberg SK, Kojima T, Mutai H, Matsunaga T, Ogawa K, Homma K. Systematic quantification of the anion transport function of pendrin (SLC26A4) and its disease-associated variants. Hum Mutat 2020; 41:316-331. [PMID: 31599023 PMCID: PMC6930342 DOI: 10.1002/humu.23930] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 01/14/2023]
Abstract
Thanks to the advent of rapid DNA sequencing technology and its prevalence, many disease-associated genetic variants are rapidly identified in many genes from patient samples. However, the subsequent effort to experimentally validate and define their pathological roles is extremely slow. Consequently, the pathogenicity of most disease-associated genetic variants is solely speculated in silico, which is no longer deemed compelling. We developed an experimental approach to efficiently quantify the pathogenic effects of disease-associated genetic variants with a focus on SLC26A4, which is essential for normal inner ear function. Alterations of this gene are associated with both syndromic and nonsyndromic hereditary hearing loss with various degrees of severity. We established HEK293T-based stable cell lines that express pendrin missense variants in a doxycycline-dependent manner, and systematically determined their anion transport activities with high accuracy in a 96-well plate format using a high throughput plate reader. Our doxycycline dosage-dependent transport assay objectively distinguishes missense variants that indeed impair the function of pendrin from those that do not (functional variants). We also found that some of these putative missense variants disrupt normal messenger RNA splicing. Our comprehensive experimental approach helps determine the pathogenicity of each pendrin variant, which should guide future efforts to benefit patients.
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Affiliation(s)
- Koichiro Wasano
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
| | - Satoe Takahashi
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Samuel K. Rosenberg
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Takashi Kojima
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Hideki Mutai
- Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
| | - Tatsuo Matsunaga
- Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
| | - Kaoru Ogawa
- Department of Otolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Kazuaki Homma
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL 60608, USA
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14
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Carvalho SDCES, Grangeiro CHP, Picanço-Albuquerque CG, Dos Anjos TO, De Molfetta GA, Silva WA, Ferraz VEDF. Contribution of SLC26A4 to the molecular diagnosis of nonsyndromic prelingual sensorineural hearing loss in a Brazilian cohort. BMC Res Notes 2018; 11:546. [PMID: 30068397 PMCID: PMC6071330 DOI: 10.1186/s13104-018-3647-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 07/24/2018] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Hereditary hearing loss (HL) is the most common sensorineural disorder in humans. Besides mutations in GJB2 and GJB6 genes, pathogenic variants in the SLC26A4 gene have been reported as a cause of hereditary HL due to its role in the physiology of the inner ear. In this research we wanted to investigate the prevalence of mutations in SLC26A4 in Brazilian patients with nonsyndromic prelingual sensorineural HL. We applied the high-resolution melting technique to screen 88 DNA samples from unrelated deaf individuals that were previously screened for GJB2, GJB6 and MT-RNR1 mutations. RESULTS The frequency of mutations in the SLC26A4 gene was 28.4%. Two novel mutations were found: p.Ile254Val and p.Asn382Lys. The mutation c.-66C>G (rs17154282) in the promoter region of SLC26A4, was the most frequent mutation found and was significantly associated with nonsyndromic prelingual sensorineural HL. After mutations in the GJB2, GJB6 and mitochondrial genes, SLC26A4 mutations are considered the next most common cause of hereditary HL in Brazilian as well as in other populations, which corroborates with our data. Furthermore, we suggest the inclusion of the SCL26A4 gene in the investigation of hereditary HL since there was an increase in the frequency of the mutations found, up to 22.7%.
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Affiliation(s)
| | - Carlos Henrique Paiva Grangeiro
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Medical Genetics Service of the University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Clarissa Gondim Picanço-Albuquerque
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Medical Genetics Service of the University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Thaís Oliveira Dos Anjos
- Center for Medical Genomics at University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Greice Andreotti De Molfetta
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Center for Medical Genomics at University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Wilson Araujo Silva
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Center for Medical Genomics at University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.,Regional Blood Center of Ribeirão Preto (FUNDHERP) of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Victor Evangelista de Faria Ferraz
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil. .,Medical Genetics Service of the University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil. .,Center for Medical Genomics at University Hospital of the Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.
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15
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Roesch S, Bernardinelli E, Nofziger C, Tóth M, Patsch W, Rasp G, Paulmichl M, Dossena S. Functional Testing of SLC26A4 Variants-Clinical and Molecular Analysis of a Cohort with Enlarged Vestibular Aqueduct from Austria. Int J Mol Sci 2018; 19:ijms19010209. [PMID: 29320412 PMCID: PMC5796158 DOI: 10.3390/ijms19010209] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 12/20/2017] [Accepted: 12/28/2017] [Indexed: 12/29/2022] Open
Abstract
The prevalence and spectrum of sequence alterations in the SLC26A4 gene, which codes for the anion exchanger pendrin, are population-specific and account for at least 50% of cases of non-syndromic hearing loss associated with an enlarged vestibular aqueduct. A cohort of nineteen patients from Austria with hearing loss and a radiological alteration of the vestibular aqueduct underwent Sanger sequencing of SLC26A4 and GJB2, coding for connexin 26. The pathogenicity of sequence alterations detected was assessed by determining ion transport and molecular features of the corresponding SLC26A4 protein variants. In this group, four uncharacterized sequence alterations within the SLC26A4 coding region were found. Three of these lead to protein variants with abnormal functional and molecular features, while one should be considered with no pathogenic potential. Pathogenic SLC26A4 sequence alterations were only found in 12% of patients. SLC26A4 sequence alterations commonly found in other Caucasian populations were not detected. This survey represents the first study on the prevalence and spectrum of SLC26A4 sequence alterations in an Austrian cohort and further suggests that genetic testing should always be integrated with functional characterization and determination of the molecular features of protein variants in order to unequivocally identify or exclude a causal link between genotype and phenotype.
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Affiliation(s)
- Sebastian Roesch
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, Müllner Hauptstraße 48, A-5020 Salzburg, Austria.
| | - Emanuele Bernardinelli
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Strubergasse 21, A-5020 Salzburg, Austria.
| | - Charity Nofziger
- PharmGenetix Gmbh, Sonystrasse 20, A-5081 Niederalm Anif, Austria.
| | - Miklós Tóth
- Department of Otorhinolaryngology, Head & Neck Surgery and Oncology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, D-20251 Hamburg, Germany.
| | - Wolfgang Patsch
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Strubergasse 21, A-5020 Salzburg, Austria.
| | - Gerd Rasp
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, Müllner Hauptstraße 48, A-5020 Salzburg, Austria.
| | - Markus Paulmichl
- Center for Health and Bioresources, Austrian Institute of Technology, Muthgasse 11, A-1190 Vienna, Austria.
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Strubergasse 21, A-5020 Salzburg, Austria.
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16
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Kallel-Bouattour R, Belguith-Maalej S, Zouari-Bradai E, Mnif M, Abid M, Hadj Kacem H. Intronic variants of SLC26A4 gene enhance splicing efficiency in hybrid minigene assay. Gene 2017; 620:10-14. [PMID: 28389359 DOI: 10.1016/j.gene.2017.03.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 03/19/2017] [Accepted: 03/31/2017] [Indexed: 12/14/2022]
Abstract
The SLC26A4 genomic sequence screening in autoimmune thyroid diseases (AITD) revealed different variants types with possible pathogenic effects. Although intronic variants may have more detrimental effects than those coding, they are poorly explored. Thus, in a first assessment, our bioinformatics analysis of intronic variants predicted a pathogenic effect of c.1002-9A>C, c.1545-5T>G and c.1544+9C>T variants. Validating these variants pathogenicity may provide new clues on the AITD physiopathology. Variants were explored in a general population by PCR-RFLP. These variants effects on the mRNA processing was assessed using functional splicing assay based in DNA hybrid minigene in HeLa cell lines. The constructs splicing efficiency was investigated by real time PCR. Our results revealed that c.1002-9A>C is a rare allele (minor frequency allele (MFA)=0.007) whereas c.1545-5T>G and c.1544+9C>T are low frequency variants. The RT-PCR analysis showed that these variants did not affect the mRNA processing. However, quantifying the transcripts generated from minigene constructs proved an mRNA splicing enhancement. Our study suggests a pathogenic effect of three intronic variants on the mRNA splicing efficiency using a DNA Hybrid minigene. By quantifying these transcripts, we unveil the limit of standard RT-PCR in analyzing a splicing minigene assay.
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Affiliation(s)
- Rihab Kallel-Bouattour
- Laboratoire Procédés de Criblage Moléculaire et Cellulaire, Centre Biotechnologie de Sfax, Tunisia
| | - Salima Belguith-Maalej
- Laboratoire Procédés de Criblage Moléculaire et Cellulaire, Centre Biotechnologie de Sfax, Tunisia
| | - Emna Zouari-Bradai
- Laboratoire Procédés de Criblage Moléculaire et Cellulaire, Centre Biotechnologie de Sfax, Tunisia
| | - Mouna Mnif
- Service d'Endocrinologie, CHU, Hédi Chaker, Sfax, Tunisia
| | - Mohamed Abid
- Service d'Endocrinologie, CHU, Hédi Chaker, Sfax, Tunisia
| | - Hassen Hadj Kacem
- Laboratoire Procédés de Criblage Moléculaire et Cellulaire, Centre Biotechnologie de Sfax, Tunisia; Department of Applied Biology, College of Sciences, University of Sharjah, United Arab Emirates.
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