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Lee HJ, Fenollar-Ferrer C, Isgrig K, Wang YX, Valente K, Eide J, Honda K, Chien WW, Petralia RS, Dong L, Friedman TB, Bonifacino JS, Griffith AJ, Roux I. SLC26A4-AP-2 mu2 interaction regulates SLC26A4 plasma membrane abundance in the endolymphatic sac. SCIENCE ADVANCES 2024; 10:eadm8663. [PMID: 39383236 DOI: 10.1126/sciadv.adm8663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 09/06/2024] [Indexed: 10/11/2024]
Abstract
Decreased presence or activity of human SLC26A4 at the plasma membrane is a common cause of hearing loss. SLC26A4 (Pendrin) is necessary for normal reabsorption of endolymph, the fluid bathing the inner ear. We identified the μ2 subunit of adaptor protein 2 (AP-2) complex required for clathrin-mediated endocytosis as a protein-partner of SLC26A4 involved in regulating its plasma membrane abundance. We showed that, in the endolymphatic sac, where fluid reabsorption occurs, SLC26A4 is localized along the apical microvilli of mitochondria-rich cells, in contact with the endolymph, and associated with clathrin-coated pits where μ2 and AP-2 are present. Based on SLC26A4 structure, the elements involved in SLC26A4-μ2 interaction were identified and validated experimentally, allowing modeling of this interaction at the atomic level. Pharmacological inhibition of clathrin-mediated endocytosis led to an increased plasma membrane abundance of hemagglutinin-tagged SLC26A4 virally or endogenously expressed in mitochondria-rich cells. These results indicate that the SLC26A4-μ2 interaction regulates SLC26A4 abundance at the apical surface of mitochondria-rich cells.
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Affiliation(s)
- Hyun Jae Lee
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Cristina Fenollar-Ferrer
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Kevin Isgrig
- Inner Ear Gene Therapy Program, Neurotology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Kerstin Valente
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Juleh Eide
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Keiji Honda
- Department of Otorhinolaryngology, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
| | - Wade W Chien
- Inner Ear Gene Therapy Program, Neurotology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Ronald S Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Lijin Dong
- Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Andrew J Griffith
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
- Department of Otolaryngology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Isabelle Roux
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
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Sansović I, Meašić AM, Bobinec A, Morožin Pohovski L, Odak L, Vulin K, Lozić B, Kero M, Huljev Frković S, Pušeljić S. Spectrum of genetic variants in 306 patients with non-syndromic hearing loss from Croatia. Croat Med J 2024; 65:198-208. [PMID: 38868966 PMCID: PMC11157262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 05/17/2024] [Indexed: 06/14/2024] Open
Abstract
AIM To determine the spectrum and frequency of disease-causing variants in patients with non-syndromic hearing loss (NSHL) and to investigate the diagnostic yield of the applied genetic methods. METHODS The study enrolled 306 unrelated patients with childhood-onset, mild-to-profound NSHL referred to Children's Hospital Zagreb for genetic testing between March 2006 and October 2023. The GJB2 variants were analyzed with the multiplex ligation-dependent probe amplification method and Sanger sequencing of the coding region of the GJB2 gene. In 21 patients negative for GJB2 biallelic variants, clinical exome sequencing (CES) was performed. RESULTS Among 234 disease-associated GJB2 alleles detected, 19 were clinically relevant, of which 18 were reported as pathogenic/likely pathogenic. The c.35delG variant accounted for 73.5% of the mutated alleles. More than half of the patients with biallelic GJB2 variants (64/110, 58.2%) were 35delG homozygotes. Seventeen non-GJB2 variants were found in 10 genes (TECTA, NOG, SLC26A4, PCDH15, TMPRSS3, USH2A, GATA3, MYO15A, SOX10, COL2A1) in 11 participants, and 5 variants (in TECTA, NOG, PCDH15, and SOX10) were novel (29.4%). CONCLUSION We were able to elucidate the genetic cause of hearing loss in 121 patients, with an overall diagnostic rate of 39.5%. The c.35delG was the most common variant. CES allowed us to diagnose almost half of the patients with HL; to distinguish NSHL from the syndromic form of HL in cases where the phenotype was unclear or where symptoms were absent from an early age; and to discover novel variants.
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Affiliation(s)
- Ivona Sansović
- Ivona Sansović, Children's Hospital Zagreb, University of Zagreb, School of Medicine, Department of Medical and Laboratory Genetics, Endocrinology and Diabetology, Klaićeva 16, 10000 Zagreb, Croatia,
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Takahashi S, Zhou Y, Cheatham MA, Homma K. The frequency dependence of prestin-mediated fast electromotility for mammalian cochlear amplification. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.22.595389. [PMID: 38826260 PMCID: PMC11142200 DOI: 10.1101/2024.05.22.595389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Prestin's voltage-driven motor activity confers sound-elicited somatic electromotility in auditory outer hair cells (OHCs) and is essential for the exquisite sensitivity and frequency selectivity of mammalian hearing. Lack of prestin results in hearing threshold shifts across frequency, supporting the causal association of variants in the prestin-coding gene, SLC26A5 , with human hearing loss, DFNB61. However, cochlear function can tolerate reductions in prestin-mediated OHC electromotility. We found that two deafness-associated prestin variants, p.A100T and p.P119S, do not deprive prestin of its fast motor function but significantly reduce membrane expression, leading to large reductions in OHC electromotility that were only ∼30% of wildtype (WT). Mice harboring these missense variants suffered congenital hearing loss that was worse at high frequencies; however, they retained WT-like auditory brainstem response thresholds at 8 kHz, which is processed at the apex of the mouse cochlea. This observation suggests the increasing importance of prestin-driven cochlear amplification at higher frequencies relevant to mammalian hearing. The observation also suggests the promising clinical possibility that small enhancements of OHC electromotility could significantly ameliorate DFNB61 hearing loss in human patients. SIGNIFICANCE Prestin is abundantly expressed in the auditory outer hair cells and is essential for normal cochlear operation. Hence, reduction of prestin expression is often taken as indicative of reduced cochlear function in diseased or aged ears. However, this assumption overlooks the fact that cochlear function can tolerate large reductions in prestin motor activity. DFNB61 mouse models generated and characterized in this study provide an opportunity to gauge the amount of prestin motor activity needed to sustain normal hearing sensitivity. This knowledge is crucial not only for understanding the pathogenic roles of deafness-associated variants that impair OHC electromotility but also for unraveling how prestin contributes to cochlear amplification.
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Takahashi S, Homma K. The molecular principles underlying diverse functions of the SLC26 family of proteins. J Biol Chem 2024; 300:107261. [PMID: 38582450 PMCID: PMC11078650 DOI: 10.1016/j.jbc.2024.107261] [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: 01/27/2024] [Revised: 03/07/2024] [Accepted: 03/30/2024] [Indexed: 04/08/2024] Open
Abstract
Mammalian SLC26 proteins are membrane-based anion transporters that belong to the large SLC26/SulP family, and many of their variants are associated with hereditary diseases. Recent structural studies revealed a strikingly similar homodimeric molecular architecture for several SLC26 members, implying a shared molecular principle. Now a new question emerges as to how these structurally similar proteins execute diverse physiological functions. In this study, we sought to identify the common versus distinct molecular mechanism among the SLC26 proteins using both naturally occurring and artificial missense changes introduced to SLC26A4, SLC26A5, and SLC26A9. We found: (i) the basic residue at the anion binding site is essential for both anion antiport of SLC26A4 and motor functions of SLC26A5, and its conversion to a nonpolar residue is crucial but not sufficient for the fast uncoupled anion transport in SLC26A9; (ii) the conserved polar residues in the N- and C-terminal cytosolic domains are likely involved in dynamic hydrogen-bonding networks and are essential for anion antiport of SLC26A4 but not for motor (SLC26A5) and uncoupled anion transport (SLC26A9) functions; (iii) the hydrophobic interaction between each protomer's last transmembrane helices, TM14, is not of functional significance in SLC26A9 but crucial for the functions of SLC26A4 and SLC26A5, likely contributing to optimally orient the axis of the relative movements of the core domain with respect to the gate domains within the cell membrane. These findings advance our understanding of the molecular mechanisms underlying the diverse physiological roles of the SLC26 family of proteins.
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Affiliation(s)
- Satoe Takahashi
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA; Center for Mechanical Excitability, The University of Chicago, Chicago, Illinois, USA
| | - Kazuaki Homma
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA; Center for Mechanical Excitability, The University of Chicago, Chicago, Illinois, USA; The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, Illinois, USA.
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Takahashi S, Zhou Y, Cheatham MA, Homma K. The pathogenic roles of the p.R130S prestin variant in DFNB61 hearing loss. J Physiol 2024; 602:1199-1210. [PMID: 38431907 PMCID: PMC10942758 DOI: 10.1113/jp285599] [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: 08/31/2023] [Accepted: 02/05/2024] [Indexed: 03/05/2024] Open
Abstract
DFNB61 is a recessively inherited nonsyndromic hearing loss caused by mutations in SLC26A5, the gene that encodes the voltage-driven motor protein, prestin. Prestin is abundantly expressed in the auditory outer hair cells that mediate cochlear amplification. Two DFNB61-associated SLC26A5 variants, p.W70X and p.R130S, were identified in patients who are compound heterozygous for these nonsense and missense changes (SLC26A5W70X/R130S ). Our recent study showed that mice homozygous for p.R130S (Slc26a5R130S/R130S ) suffer from hearing loss that is ascribed to significantly reduced motor kinetics of prestin. Given that W70X-prestin is nonfunctional, compound heterozygous Slc26a5R130S/- mice were used as a model for human SLC26A5W70X/R130S . By examining the pathophysiological consequences of p.R130S prestin when it is the sole allele for prestin protein production, we determined that this missense change results in progressive outer hair cell loss in addition to its effects on prestin's motor action. Thus, this study defines the pathogenic roles of p.R130S prestin and identifies a limited time window for potential clinical intervention. KEY POINTS: The voltage-driven motor protein, prestin, is encoded by SLC26A5 and expressed abundantly in cochlear outer hair cells (OHCs). The importance of prestin for normal hearing was demonstrated in mice lacking prestin; however, none of the specific SLC26A5 variants identified to date in human patients has been experimentally demonstrated to be pathogenic. In this study we used both cell lines and a mouse model to define the pathogenic role of compound heterozygous p.W70X (c.209G>A) and p.R130S (c.390A>C) SLC26A5 variants identified in patients with moderate to profound hearing loss. As in patients, mice carrying one copy of p.R130S Slc26a5 showed OHC dysfunction and progressive degeneration, which results in congenital progressive hearing loss. This is the first functional study reporting pathogenic SLC26A5 variants and pointing to the presence of a therapeutic time window for potential clinical interventions targeting the affected OHCs before they are lost.
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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
| | - Yingjie Zhou
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA
| | - Mary Ann Cheatham
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders
| | - 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
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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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Li YQ, Ma H, Wang QY, Liu DS, Wang W, Li SX, Zuo RX, Shen T, Zhu BS, Sa YL. Low frequency of SLC26A4 c.919-2A > G variant among patients with nonsyndromic hearing loss in Yunnan of Southwest China. BMC Med Genomics 2024; 17:55. [PMID: 38378613 PMCID: PMC10877886 DOI: 10.1186/s12920-024-01829-3] [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: 02/10/2023] [Accepted: 02/09/2024] [Indexed: 02/22/2024] Open
Abstract
BACKGROUND Gene variants are responsible for more than half of hearing loss, particularly in nonsyndromic hearing loss (NSHL). The most common pathogenic variant in SLC26A4 gene found in East Asian populations is c.919-2A > G followed by c.2168A > G (p.H723R). This study was to evaluate their variant frequencies in patients with NSHL from special education schools in nine different areas of Southwest China's Yunnan. METHODS We performed molecular characterization by PCR-products directly Sanger sequencing of the SLC26A4 c.919-2AG and c.2168 A > G variants in 1167 patients with NSHL including 533 Han Chinese and 634 ethnic minorities. RESULTS The SLC26A4 c.919-2A > G variant was discovered in 8 patients with a homozygous state (0.69%) and twenty-five heterozygous (2.14%) in 1167 patients with NSHL. The total carrier rate of the c.919-2A > G variant was found in Han Chinese patients with 4.50% and ethnic minority patients with 1.42%. A significant difference existed between the two groups (P < 0.05). The c.919-2A > G allele variant frequency was ranged from 3.93% in Kunming to zero in Lincang and Nvjiang areas of Yunnan. We further detected the SLC26A4 c.2168 A > G variant in this cohort with one homozygotes (0.09%) and seven heterozygotes (0.60%), which was detected in Baoshan, Honghe, Licang and Pu`er areas. Between Han Chinese group (0.94%) and ethnic minority group (0.47%), there was no statistical significance (P > 0.05). Three Han Chinese patients (0.26%) carried compound heterozygosity for c.919-2A > G and c.2168 A > G. CONCLUSION These data suggest that the variants in both SLC26A4 c.919-2A > G and c.2168 A > G were relatively less frequencies in this cohort compared to the average levels in most regions of China, as well as significantly lower than that in Han-Chinese patients. These results broadened Chinese population genetic information resources and provided more detailed information for regional genetic counselling for Yunnan.
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Affiliation(s)
- Yan-Qiong Li
- Center for Clinical Medicine Research (Yunnan Provincial Key Laboratory of Clinical Virology, 202205AG070053, L-2019003), The First People's Hospital of Yunnan Province (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China
- Central Sterile Supply Department, The First People's Hospital of Yunnan Province, (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China
| | - Heng Ma
- The Outpatient Department of Yanan Hospital Affiliated to Kunming Medical University, Kunming, 650051, Yunnan, China
| | - Qin-Yao Wang
- Center for Clinical Medicine Research (Yunnan Provincial Key Laboratory of Clinical Virology, 202205AG070053, L-2019003), The First People's Hospital of Yunnan Province (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China
| | - De-Sheng Liu
- Center for Clinical Medicine Research (Yunnan Provincial Key Laboratory of Clinical Virology, 202205AG070053, L-2019003), The First People's Hospital of Yunnan Province (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China
- The Emergency Department of Traditional Chinese Medicine Hospital of Sichuan Province, (The Affiliated Hospital of Chengdu University of Traditional Chinese Medicine), Chengdu, 610075, Sichuan, China
| | - Wei Wang
- Center for Clinical Medicine Research (Yunnan Provincial Key Laboratory of Clinical Virology, 202205AG070053, L-2019003), The First People's Hospital of Yunnan Province (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China
| | - Shi-Xin Li
- Center for Clinical Medicine Research (Yunnan Provincial Key Laboratory of Clinical Virology, 202205AG070053, L-2019003), The First People's Hospital of Yunnan Province (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China
| | - Rong-Xia Zuo
- Center for Clinical Medicine Research (Yunnan Provincial Key Laboratory of Clinical Virology, 202205AG070053, L-2019003), The First People's Hospital of Yunnan Province (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China
| | - Tao Shen
- Center for Clinical Medicine Research (Yunnan Provincial Key Laboratory of Clinical Virology, 202205AG070053, L-2019003), The First People's Hospital of Yunnan Province (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China
| | - Bao-Sheng Zhu
- Center of Genetic Diagnosis (Yunnan Provincial Key Laboratory for Birth Defects and Genetic Diseases), The First People's Hospital of Yunnan Province (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China
| | - Ya-Lian Sa
- Center for Clinical Medicine Research (Yunnan Provincial Key Laboratory of Clinical Virology, 202205AG070053, L-2019003), The First People's Hospital of Yunnan Province (The Affiliated Hospital of Kunming University of Science and Technology/School of Medicine), Kunming, 650032, Yunnan, China.
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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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Wang L, Hoang A, Gil-Iturbe E, Laganowsky A, Quick M, Zhou M. Mechanism of anion exchange and small-molecule inhibition of pendrin. Nat Commun 2024; 15:346. [PMID: 38184688 PMCID: PMC10771415 DOI: 10.1038/s41467-023-44612-1] [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: 06/24/2023] [Accepted: 12/21/2023] [Indexed: 01/08/2024] Open
Abstract
Pendrin (SLC26A4) is an anion exchanger that mediates bicarbonate (HCO3-) exchange for chloride (Cl-) and is crucial for maintaining pH and salt homeostasis in the kidney, lung, and cochlea. Pendrin also exports iodide (I-) in the thyroid gland. Pendrin mutations in humans lead to Pendred syndrome, causing hearing loss and goiter. Inhibition of pendrin is a validated approach for attenuating airway hyperresponsiveness in asthma and for treating hypertension. However, the mechanism of anion exchange and its inhibition by drugs remains poorly understood. We applied cryo-electron microscopy to determine structures of pendrin from Sus scrofa in the presence of either Cl-, I-, HCO3- or in the apo-state. The structures reveal two anion-binding sites in each protomer, and functional analyses show both sites are involved in anion exchange. The structures also show interactions between the Sulfate Transporter and Anti-Sigma factor antagonist (STAS) and transmembrane domains, and mutational studies suggest a regulatory role. We also determine the structure of pendrin in a complex with niflumic acid (NFA), which uncovers a mechanism of inhibition by competing with anion binding and impeding the structural changes necessary for anion exchange. These results reveal directions for understanding the mechanisms of anion selectivity and exchange and their regulations by the STAS domain. This work also establishes a foundation for analyzing the pathophysiology of mutations associated with Pendred syndrome.
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Affiliation(s)
- Lie Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Anthony Hoang
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Eva Gil-Iturbe
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, USA
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, TX, USA
| | - Matthias Quick
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, USA.
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA.
- Area Neuroscience - Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA.
| | - Ming Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA.
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Takahashi S, Homma K. The molecular principles underlying diverse functions of the SLC26 family of proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.10.570988. [PMID: 38106153 PMCID: PMC10723444 DOI: 10.1101/2023.12.10.570988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Mammalian SLC26 proteins are membrane-based anion transporters that belong to the large SLC26/SulP family, and many of their variants are associated with hereditary diseases. Recent structural studies revealed a strikingly similar homodimeric molecular architecture for several SLC26 members, implying a shared molecular principle. Now a new question emerges as to how these structurally similar proteins execute diverse physiological functions. In this study we sought to identify the common vs. distinct molecular mechanism among the SLC26 proteins using both naturally occurring and artificial missense changes introduced to SLC26A4, SLC26A5, and SLC26A9. We found: (i) the basic residue at the anion binding site is essential for both anion antiport of SLC26A4 and motor functions of SLC26A5, and its conversion to a nonpolar residue is crucial but not sufficient for the fast uncoupled anion transport in SLC26A9; (ii) the conserved polar residues in the N- and C-terminal cytosolic domains are likely involved in dynamic hydrogen-bonding networks and are essential for anion antiport of SLC26A4 but not for motor (SLC26A5) and uncoupled anion transport (SLC26A9) functions; (iii) the hydrophobic interaction between each protomer's last transmembrane helices, TM14, is not of functional significance in SLC26A9 but crucial for the functions of SLC26A4 and SLC26A5, likely contributing to optimally orient the axis of the relative movements of the core domain with respect to the gate domains within the cell membrane. These findings advance our understanding of the molecular mechanisms underlying the diverse physiological roles of the SLC26 family of proteins.
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Takahashi S, Zhou Y, Cheatham MA, Homma K. The pathogenic roles of the p.R130S prestin variant in DFNB61 hearing loss. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.21.554157. [PMID: 37662362 PMCID: PMC10473669 DOI: 10.1101/2023.08.21.554157] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
DFNB61 is a recessively inherited nonsyndromic hearing loss caused by mutations in SLC26A5 , the gene that encodes the voltage-driven motor protein, prestin. Prestin is abundantly expressed in the auditory outer hair cells that mediate cochlear amplification. Two DFNB61-associated SLC26A5 variants, p.W70X and p.R130S, were identified in patients who are compound heterozygous for these nonsense and missense changes ( SLC26A5 W70X/R130S ). Our recent study showed that mice homozygous for p.R130S ( Slc26a5 R130S/R130S ) suffer from hearing loss that is ascribed to significantly reduced motor kinetics of prestin. Given that W70X-prestin is nonfunctional, compound heterozygous Slc26a5 R130S/- mice were used as a model for human SLC26A5 W70X/R130S . By examining the pathophysiological consequences of p.R130S prestin when it is the sole allele for prestin protein production, we determined that this missense change results in progressive outer hair cell loss in addition to its effects on prestin's motor action. Thus, this study fully defines the pathogenic roles for the p.R130S prestin, which points to the presence of a limited time window for potential clinical intervention.
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12
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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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13
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Takahashi S, Zhou Y, Kojima T, Cheatham MA, Homma K. Prestin's fast motor kinetics is essential for mammalian cochlear amplification. Proc Natl Acad Sci U S A 2023; 120:e2217891120. [PMID: 36893263 PMCID: PMC10089206 DOI: 10.1073/pnas.2217891120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/06/2023] [Indexed: 03/11/2023] Open
Abstract
Prestin (SLC26A5)-mediated voltage-driven elongations and contractions of sensory outer hair cells within the organ of Corti are essential for mammalian cochlear amplification. However, whether this electromotile activity directly contributes on a cycle-by-cycle basis is currently controversial. By restoring motor kinetics in a mouse model expressing a slowed prestin missense variant, this study provides experimental evidence acknowledging the importance of fast motor action to mammalian cochlear amplification. Our results also demonstrate that the point mutation in prestin disrupting anion transport in other proteins of the SLC26 family does not alter cochlear function, suggesting that the potential weak anion transport of prestin is not essential in the mammalian cochlea.
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Affiliation(s)
- Satoe Takahashi
- Department of Otolaryngology–Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
| | - Yingjie Zhou
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL60208
| | - Takashi Kojima
- Department of Otolaryngology–Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
| | - Mary Ann Cheatham
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL60208
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL60208
| | - Kazuaki Homma
- Department of Otolaryngology–Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL60208
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14
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Danilchenko VY, Zytsar MV, Maslova EA, Posukh OL. Selection of Diagnostically Significant Regions of the SLC26A4 Gene Involved in Hearing Loss. Int J Mol Sci 2022; 23:ijms232113453. [PMID: 36362242 PMCID: PMC9655724 DOI: 10.3390/ijms232113453] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/23/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
Screening pathogenic variants in the SLC26A4 gene is an important part of molecular genetic testing for hearing loss (HL) since they are one of the common causes of hereditary HL in many populations. However, a large size of the SLC26A4 gene (20 coding exons) predetermines the difficulties of its complete mutational analysis, especially in large samples of patients. In addition, the regional or ethno-specific prevalence of SLC26A4 pathogenic variants has not yet been fully elucidated, except variants c.919-2A>G and c.2168A>G (p.His723Arg), which have been proven to be most common in Asian populations. We explored the distribution of currently known pathogenic and likely pathogenic (PLP) variants across the SLC26A4 gene sequence presented in the Deafness Variation Database for the selection of potential diagnostically important parts of this gene. As a result of this bioinformatic analysis, we found that molecular testing ten SLC26A4 exons (4, 6, 10, 11, 13−17 and 19) with flanking intronic regions can provide a diagnostic rate of 61.9% for all PLP variants in the SLC26A4 gene. The primary sequencing of these SLC26A4 regions may be applied as an initial effective diagnostic testing in samples of patients of unknown ethnicity or as a subsequent step after the targeted testing of already-known ethno- or region-specific pathogenic SLC26A4 variants.
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Affiliation(s)
- Valeriia Yu. Danilchenko
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Marina V. Zytsar
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | - Ekaterina A. Maslova
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Olga L. Posukh
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia
- Novosibirsk State University, 630090 Novosibirsk, Russia
- Correspondence:
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15
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Futamata H, Fukuda M, Umeda R, Yamashita K, Tomita A, Takahashi S, Shikakura T, Hayashi S, Kusakizako T, Nishizawa T, Homma K, Nureki O. Cryo-EM structures of thermostabilized prestin provide mechanistic insights underlying outer hair cell electromotility. Nat Commun 2022; 13:6208. [PMID: 36266333 PMCID: PMC9584906 DOI: 10.1038/s41467-022-34017-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 10/11/2022] [Indexed: 01/11/2023] Open
Abstract
Outer hair cell elecromotility, driven by prestin, is essential for mammalian cochlear amplification. Here, we report the cryo-EM structures of thermostabilized prestin (PresTS), complexed with chloride, sulfate, or salicylate at 3.52-3.63 Å resolutions. The central positively-charged cavity allows flexible binding of various anion species, which likely accounts for the known distinct modulations of nonlinear capacitance (NLC) by different anions. Comparisons of these PresTS structures with recent prestin structures suggest rigid-body movement between the core and gate domains, and provide mechanistic insights into prestin inhibition by salicylate. Mutations at the dimeric interface severely diminished NLC, suggesting that stabilization of the gate domain facilitates core domain movement, thereby contributing to the expression of NLC. These findings advance our understanding of the molecular mechanism underlying mammalian cochlear amplification.
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Affiliation(s)
- Haon Futamata
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masahiro Fukuda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo; Meguro-ku, Tokyo, 153-8503, Japan
| | - Rie Umeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Keitaro Yamashita
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Atsuhiro Tomita
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Satoe Takahashi
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Takafumi Shikakura
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Shigehiko Hayashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Tsukasa Kusakizako
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tomohiro Nishizawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, 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.
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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16
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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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17
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Kojima T, Wasano K, Takahashi S, Homma K. Cell death-inducing cytotoxicity in truncated KCNQ4 variants associated with DFNA2 hearing loss. Dis Model Mech 2021; 14:272416. [PMID: 34622280 PMCID: PMC8628632 DOI: 10.1242/dmm.049015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 09/22/2021] [Indexed: 01/30/2023] Open
Abstract
KCNQ4 encodes the homotetrameric voltage-dependent potassium ion channel Kv7.4, and is the causative gene for autosomal dominant nonsyndromic sensorineural hearing loss, DFNA2. Dominant-negative inhibition accounts for the observed dominant inheritance of many DFNA2-associated KCNQ4 variants. In addition, haploinsufficiency has been presumed as the pathological mechanism for truncated Kv7.4 variants lacking the C-terminal tetramerization region, as they are unlikely to exert a dominant-negative inhibitory effect. Such truncated Kv7.4 variants should result in relatively mild hearing loss when heterozygous; however, this is not always the case. In this study, we characterized Kv7.4Q71fs (c.211delC), Kv7.4W242X (c.725G>A) and Kv7.4A349fs (c.1044_1051del8) in heterologous expression systems and found that expression of these truncated Kv7.4 variants induced cell death. We also found similar cell death-inducing cytotoxic effects in truncated Kv7.1 (KCNQ1) variants, suggesting that the generality of our findings could account for the dominant inheritance of many, if not most, truncated Kv7 variants. Moreover, we found that the application of autophagy inducers can ameliorate the cytotoxicity, providing a novel insight for the development of alternative therapeutic strategies for Kv7.4 variants. Summary: Expression of truncated KCNQ4 variants lacking the C-terminal tetramerization domain results in cell-death inducing cytotoxicity, providing novel insight into the development of alternative therapeutic strategies for DFNA2 hearing loss.
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Affiliation(s)
- 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, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan
| | - 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
| | - 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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18
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Tesolin P, Fiorino S, Lenarduzzi S, Rubinato E, Cattaruzzi E, Ammar L, Castro V, Orzan E, Granata C, Dell’Orco D, Morgan A, Girotto G. Pendred Syndrome, or Not Pendred Syndrome? That Is the Question. Genes (Basel) 2021; 12:1569. [PMID: 34680964 PMCID: PMC8535891 DOI: 10.3390/genes12101569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/27/2021] [Accepted: 09/29/2021] [Indexed: 11/16/2022] Open
Abstract
Pendred syndrome (PDS) is the most common form of syndromic Hearing Loss (HL), characterized by sensorineural HL, inner ear malformations, and goiter, with or without hypothyroidism. SLC26A4 is the major gene involved, even though ~50% of the patients carry only one pathogenic mutation. This study aims to define the molecular diagnosis for a cohort of 24 suspected-PDS patients characterized by a deep radiological and audiological evaluation. Whole-Exome Sequencing (WES), the analysis of twelve variants upstream of SLC26A4, constituting the "CEVA haplotype" and Multiplex Ligation Probe Amplification (MLPA) searching for deletions/duplications in SLC26A4 gene have been carried out. In five patients (20.8%) homozygous/compound heterozygous SLC26A4 mutations, or pathogenic mutation in trans with the CEVA haplotype have been identified, while five subjects (20.8%) resulted heterozygous for a single variant. In silico protein modeling supported the pathogenicity of the detected variants, suggesting an effect on the protein stabilization/function. Interestingly, we identified a genotype-phenotype correlation among those patients carrying SLC26A4 mutations, whose audiograms presented a characteristic slope at the medium and high frequencies, providing new insights into PDS. Finally, an interesting homozygous variant in MYO5C has been identified in one patient negative to SLC26A4 gene, suggesting the identification of a new HL candidate gene.
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Affiliation(s)
- Paola Tesolin
- Department of Medicine, Surgery and Health Sciences, University of Trieste, 34149 Trieste, Italy;
| | - Sofia Fiorino
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy;
| | - Stefania Lenarduzzi
- Institute for Maternal and Child Health—IRCCS, Burlo Garofolo, 34127 Trieste, Italy; (S.L.); (E.R.); (E.C.); (L.A.); (V.C.); (E.O.); (C.G.); (A.M.)
| | - Elisa Rubinato
- Institute for Maternal and Child Health—IRCCS, Burlo Garofolo, 34127 Trieste, Italy; (S.L.); (E.R.); (E.C.); (L.A.); (V.C.); (E.O.); (C.G.); (A.M.)
| | - Elisabetta Cattaruzzi
- Institute for Maternal and Child Health—IRCCS, Burlo Garofolo, 34127 Trieste, Italy; (S.L.); (E.R.); (E.C.); (L.A.); (V.C.); (E.O.); (C.G.); (A.M.)
| | - Lydie Ammar
- Institute for Maternal and Child Health—IRCCS, Burlo Garofolo, 34127 Trieste, Italy; (S.L.); (E.R.); (E.C.); (L.A.); (V.C.); (E.O.); (C.G.); (A.M.)
| | - Veronica Castro
- Institute for Maternal and Child Health—IRCCS, Burlo Garofolo, 34127 Trieste, Italy; (S.L.); (E.R.); (E.C.); (L.A.); (V.C.); (E.O.); (C.G.); (A.M.)
| | - Eva Orzan
- Institute for Maternal and Child Health—IRCCS, Burlo Garofolo, 34127 Trieste, Italy; (S.L.); (E.R.); (E.C.); (L.A.); (V.C.); (E.O.); (C.G.); (A.M.)
| | - Claudio Granata
- Institute for Maternal and Child Health—IRCCS, Burlo Garofolo, 34127 Trieste, Italy; (S.L.); (E.R.); (E.C.); (L.A.); (V.C.); (E.O.); (C.G.); (A.M.)
| | - Daniele Dell’Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37129 Verona, Italy;
| | - Anna Morgan
- Institute for Maternal and Child Health—IRCCS, Burlo Garofolo, 34127 Trieste, Italy; (S.L.); (E.R.); (E.C.); (L.A.); (V.C.); (E.O.); (C.G.); (A.M.)
| | - Giorgia Girotto
- Department of Medicine, Surgery and Health Sciences, University of Trieste, 34149 Trieste, Italy;
- Institute for Maternal and Child Health—IRCCS, Burlo Garofolo, 34127 Trieste, Italy; (S.L.); (E.R.); (E.C.); (L.A.); (V.C.); (E.O.); (C.G.); (A.M.)
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19
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Honda K, Griffith AJ. Genetic architecture and phenotypic landscape of SLC26A4-related hearing loss. Hum Genet 2021; 141:455-464. [PMID: 34345941 DOI: 10.1007/s00439-021-02311-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 06/29/2021] [Indexed: 12/15/2022]
Abstract
Mutations of coding regions and splice sites of SLC26A4 cause Pendred syndrome and nonsyndromic recessive hearing loss DFNB4. SLC26A4 encodes pendrin, a transmembrane exchanger of anions and bases. The mutant SLC26A4 phenotype is characterized by inner ear malformations, including an enlarged vestibular aqueduct (EVA), incomplete cochlear partition type II and modiolar hypoplasia, progressive and fluctuating hearing loss, and vestibular dysfunction. A thyroid iodine organification defect can lead to multinodular goiter and distinguishes Pendred syndrome from DFNB4. Pendred syndrome and DFNB4 are each inherited as an autosomal recessive trait caused by biallelic mutations of SLC26A4 (M2). However, there are some EVA patients with only one detectable mutant allele (M1) of SLC26A4. In most European-Caucasian M1 patients, there is a haplotype that consists of 12 variants upstream of SLC26A4, called CEVA (Caucasian EVA), which acts as a pathogenic recessive allele in trans to mutations affecting the coding regions or splice sites of SLC26A4. This combination of an M1 genotype with the CEVA haplotype is associated with a less severe phenotype than the M2 genotype. The phenotype in EVA patients with no mutant alleles of SLC26A4 (M0) has a very low recurrence probability and is likely to be caused by other factors.
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Affiliation(s)
- Keiji Honda
- Department of Otorhinolaryngology, Tokyo Medical and Dental University (TMDU), Bunkyo-ku, Tokyo, Japan
| | - Andrew J Griffith
- Department of Otolaryngology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA.
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