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Vartanian V, Krey JF, Chatterjee P, Curtis A, Six M, Rice SPM, Jones SM, Sampath H, Allen CN, Ryals RC, Lloyd RS, Barr‐Gillespie PG. Spontaneous allelic variant in deafness-blindness gene Ush1g resulting in an expanded phenotype. GENES, BRAIN, AND BEHAVIOR 2023; 22:e12849. [PMID: 37328946 PMCID: PMC10393423 DOI: 10.1111/gbb.12849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 05/05/2023] [Accepted: 05/07/2023] [Indexed: 06/18/2023]
Abstract
Relationships between novel phenotypic behaviors and specific genetic alterations are often discovered using target-specific, directed mutagenesis or phenotypic selection following chemical mutagenesis. An alternative approach is to exploit deficiencies in DNA repair pathways that maintain genetic integrity in response to spontaneously induced damage. Mice deficient in the DNA glycosylase NEIL1 show elevated spontaneous mutations, which arise from translesion DNA synthesis past oxidatively induced base damage. Several litters of Neil1 knockout mice included animals that were distinguished by their backwards-walking behavior in open-field environments, while maintaining frantic forward movements in their home cage environment. Other phenotypic manifestations included swim test failures, head tilting and circling. Mapping of the mutation that conferred these behaviors showed the introduction of a stop codon at amino acid 4 of the Ush1g gene. Ush1gbw/bw null mice displayed auditory and vestibular defects that are commonly seen with mutations affecting inner-ear hair-cell function, including a complete lack of auditory brainstem responses and vestibular-evoked potentials. As in other Usher syndrome type I mutant mouse lines, hair cell phenotypes included disorganized and split hair bundles, as well as altered distribution of proteins for stereocilia that localize to the tips of row 1 or row 2. Disruption to the bundle and kinocilium displacement suggested that USH1G is essential for forming the hair cell's kinocilial links. Consistent with other Usher type 1 models, Ush1gbw/bw mice had no substantial retinal degeneration compared with Ush1gbw /+ controls. In contrast to previously described Ush1g alleles, this new allele provides the first knockout model for this gene.
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Affiliation(s)
- Vladimir Vartanian
- Oregon Institute of Occupational Health SciencesOregon Health & Science UniversityPortlandOregonUSA
| | - Jocelyn F. Krey
- Oregon Hearing Research Center and Vollum InstituteOregon Health & Science UniversityPortlandOregonUSA
| | - Paroma Chatterjee
- Oregon Hearing Research Center and Vollum InstituteOregon Health & Science UniversityPortlandOregonUSA
| | - Allison Curtis
- Department of Ophthalmology, Casey Eye InstituteOregon Health & Science UniversityPortlandOregonUSA
| | - Makayla Six
- Department of Ophthalmology, Casey Eye InstituteOregon Health & Science UniversityPortlandOregonUSA
| | - Sean P. M. Rice
- Oregon Institute of Occupational Health Sciences and School of Public HealthOregon Health & Science University‐Portland State UniversityPortlandOregonUSA
| | - Sherri M. Jones
- Department of Special Education and Communication DisordersUniversity of Nebraska‐LincolnLincolnNebraskaUSA
| | - Harini Sampath
- Department of Nutritional Sciences and New Jersey Institute for Food, Nutrition, and HealthRutgers UniversityNew BrunswickNew JerseyUSA
| | - Charles N. Allen
- Oregon Institute of Occupational Health Sciences and Department of Behavioral NeuroscienceOregon Health & Science UniversityPortlandOregonUSA
| | - Renee C. Ryals
- Department of Ophthalmology, Casey Eye InstituteOregon Health & Science UniversityPortlandOregonUSA
| | - R. Stephen Lloyd
- Oregon Institute of Occupational Health SciencesOregon Health & Science UniversityPortlandOregonUSA
- Department of Molecular and Medical GeneticsOregon Health & Science UniversityPortlandOregonUSA
| | - Peter G. Barr‐Gillespie
- Oregon Hearing Research Center and Vollum InstituteOregon Health & Science UniversityPortlandOregonUSA
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Krey JF, Chatterjee P, Halford J, Cunningham CL, Perrin BJ, Barr-Gillespie PG. Control of stereocilia length during development of hair bundles. PLoS Biol 2023; 21:e3001964. [PMID: 37011103 PMCID: PMC10101650 DOI: 10.1371/journal.pbio.3001964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 04/13/2023] [Accepted: 03/14/2023] [Indexed: 04/05/2023] Open
Abstract
Assembly of the hair bundle, the sensory organelle of the inner ear, depends on differential growth of actin-based stereocilia. Separate rows of stereocilia, labeled 1 through 3 from tallest to shortest, lengthen or shorten during discrete time intervals during development. We used lattice structured illumination microscopy and surface rendering to measure dimensions of stereocilia from mouse apical inner hair cells during early postnatal development; these measurements revealed a sharp transition at postnatal day 8 between stage III (row 1 and 2 widening; row 2 shortening) and stage IV (final row 1 lengthening and widening). Tip proteins that determine row 1 lengthening did not accumulate simultaneously during stages III and IV; while the actin-bundling protein EPS8 peaked at the end of stage III, GNAI3 peaked several days later-in early stage IV-and GPSM2 peaked near the end of stage IV. To establish the contributions of key macromolecular assemblies to bundle structure, we examined mouse mutants that eliminated tip links (Cdh23v2J or Pcdh15av3J), transduction channels (TmieKO), or the row 1 tip complex (Myo15ash2). Cdh23v2J/v2J and Pcdh15av3J/av3J bundles had adjacent stereocilia in the same row that were not matched in length, revealing that a major role of these cadherins is to synchronize lengths of side-by-side stereocilia. Use of the tip-link mutants also allowed us to distinguish the role of transduction from effects of transduction proteins themselves. While levels of GNAI3 and GPSM2, which stimulate stereocilia elongation, were greatly attenuated at the tips of TmieKO/KO row 1 stereocilia, they accumulated normally in Cdh23v2J/v2J and Pcdh15av3J/av3J stereocilia. These results reinforced the suggestion that the transduction proteins themselves facilitate localization of proteins in the row 1 complex. By contrast, EPS8 concentrates at tips of all TmieKO/KO, Cdh23v2J/v2J, and Pcdh15av3J/av3J stereocilia, correlating with the less polarized distribution of stereocilia lengths in these bundles. These latter results indicated that in wild-type hair cells, the transduction complex prevents accumulation of EPS8 at the tips of shorter stereocilia, causing them to shrink (rows 2 and 3) or disappear (row 4 and microvilli). Reduced rhodamine-actin labeling at row 2 stereocilia tips of tip-link and transduction mutants suggests that transduction's role is to destabilize actin filaments there. These results suggest that regulation of stereocilia length occurs through EPS8 and that CDH23 and PCDH15 regulate stereocilia lengthening beyond their role in gating mechanotransduction channels.
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Affiliation(s)
- Jocelyn F. Krey
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Paroma Chatterjee
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Julia Halford
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Christopher L. Cunningham
- Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Benjamin J. Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Peter G. Barr-Gillespie
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
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Abstract
Usher syndrome (USH) is the most common genetic condition responsible for combined loss of hearing and vision. Balance disorders and bilateral vestibular areflexia are also observed in some cases. The syndrome was first described by Albrecht von Graefe in 1858, but later named by Charles Usher, who presented a large number of cases with hearing loss and retinopathy in 1914. USH has been grouped into three main clinical types: 1, 2, and 3, which are caused by mutations in different genes and are further divided into different subtypes. To date, nine causative genes have been identified and confirmed as responsible for the syndrome when mutated: MYO7A, USH1C, CDH23, PCDH15, and USH1G (SANS) for Usher type 1; USH2A, ADGRV1, and WHRN for Usher type 2; CLRN1 for Usher type 3. USH is inherited in an autosomal recessive pattern. Digenic, bi-allelic, and polygenic forms have also been reported, in addition to dominant or nonsyndromic forms of genetic mutations. This narrative review reports the causative forms, diagnosis, prognosis, epidemiology, rehabilitation, research, and new treatments of USH.
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Markova TG, Alekseeva NN, Belov OA, Chugunova TI, Tsygankova ER. [Hearing loss due to mutations in the genes responsible for Usher syndrome]. Vestn Otorinolaringol 2022; 87:52-59. [PMID: 35274893 DOI: 10.17116/otorino20228701152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Usher syndrome is characterized by congenital bilateral sensorineural hearing loss and progressive retinitis pigmentosa, and has an autosomal recessive type of inheritance. The purpose of this work is to summarize the modern data of a clinical picture of Usher syndrome and analyse hearing impairment properties. The frequency of the syndrome among children suffering from hearing loss and deafness is from 3 to 10%. The prevalence of the syndrome in the world is estimated as 4.4 per 100.000 population. The complexity of the diagnosis of the syndrome lies in the significant clinical and genetic heterogeneity. Hearing and vision problems begin at different ages. Primary diagnosis begins with the clinical diagnosis of bilateral hearing loss and visual impairment manifests later. In this case the initial diagnosis of nonsyndromal hearing loss will not be definitive. Molecular genetic studies contribute to the early clinical diagnosis of the syndrome. Understanding the cause of the disease allows to conduct correct medical and genetic counseling and get closer to solving treatment problems.
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Affiliation(s)
- T G Markova
- National Research Centre for Audiology and Hearing Rehabilitation, Moscow, Russia
- Russian Medical Academy for Continuous Professional Education Audiology Department, Moscow, Russia
| | - N N Alekseeva
- National Research Centre for Audiology and Hearing Rehabilitation, Moscow, Russia
- Russian Medical Academy for Continuous Professional Education Audiology Department, Moscow, Russia
| | - O A Belov
- National Research Centre for Audiology and Hearing Rehabilitation, Moscow, Russia
| | - T I Chugunova
- National Research Centre for Audiology and Hearing Rehabilitation, Moscow, Russia
| | - E R Tsygankova
- National Research Centre for Audiology and Hearing Rehabilitation, Moscow, Russia
- Russian Medical Academy for Continuous Professional Education Audiology Department, Moscow, Russia
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Pacentine IV, Barr-Gillespie PG. Cy3-ATP labeling of unfixed, permeabilized mouse hair cells. Sci Rep 2021; 11:23855. [PMID: 34903829 PMCID: PMC8668996 DOI: 10.1038/s41598-021-03365-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 12/01/2021] [Indexed: 12/02/2022] Open
Abstract
ATP-utilizing enzymes play key roles in hair bundles, the mechanically sensitive organelles of sensory hair cells in the inner ear. We used a fluorescent ATP analog, EDA-ATP-Cy3 (Cy3-ATP), to label ATP-binding proteins in two different preparations of unfixed hair-cell stereocilia of the mouse. In the first preparation, we lightly permeabilized dissected cochleas, then labeled them with Cy3-ATP. Hair cells and their stereocilia remained intact, and stereocilia tips in rows 1 and 2 were labeled particularly strongly with Cy3-ATP. In many cases, vanadate (Vi) traps nucleotides at the active site of myosin isoforms and presents nucleotide dissociation. Co-application with Vi enhanced the tip labeling, which is consistent with myosin isoforms being responsible. By contrast, the actin polymerization inhibitors latrunculin A and cytochalasin D had no effect, suggesting that actin turnover at stereocilia tips was not involved. Cy3-ATP labeling was substantially reduced—but did not disappear altogether—in mutant cochleas lacking MYO15A; by contrast, labeling remained robust in cochleas lacking MYO7A. In the second preparation, used to quantify Cy3-ATP labeling, we labeled vestibular stereocilia that had been adsorbed to glass, which demonstrated that tip labeling was higher in longer stereocilia. We found that tip signal was reduced by ~ 50% in Myo15ash2/sh2 stereocilia as compared to Myo15ash2/+stereocilia. These results suggest that MYO15A accounts for a substantial fraction of the Cy3-ATP tip labeling in vestibular hair cells, and so this novel preparation could be utilized to examine the control of MYO15A ATPase activity in situ.
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Affiliation(s)
- Itallia V Pacentine
- Oregon Hearing Research Center & Vollum Institute, Mail Code L335A, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center & Vollum Institute, Mail Code L335A, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
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Roman-Naranjo P, Moleon MDC, Aran I, Escalera-Balsera A, Soto-Varela A, Bächinger D, Gomez-Fiñana M, Eckhard AH, Lopez-Escamez JA. Rare coding variants involving MYO7A and other genes encoding stereocilia link proteins in familial meniere disease. Hear Res 2021; 409:108329. [PMID: 34391192 DOI: 10.1016/j.heares.2021.108329] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/27/2021] [Accepted: 07/27/2021] [Indexed: 11/25/2022]
Abstract
The MYO7A gene encodes a motor protein with a key role in the organization of stereocilia in auditory and vestibular hair cells. Rare variants in the MYO7A (myosin VIIA) gene may cause autosomal dominant (AD) or autosomal recessive (AR) sensorineural hearing loss (SNHL) accompanied by vestibular dysfunction or retinitis pigmentosa (Usher syndrome type 1B). Familial Meniere's disease (MD) is a rare inner ear syndrome mainly characterized by low-frequency sensorineural hearing loss and episodic vertigo associated with tinnitus. Familial aggregation has been found in 6-8% of sporadic cases, and most of the reported genes were involved in single families. Thus, this study aimed to search for relevant genes not previously linked to familial MD. Through exome sequencing and segregation analysis in 62 MD families, we have found a total of 1 novel and 8 rare heterozygous variants in the MYO7A gene in 9 non-related families. Carriers of rare variants in MYO7A showed autosomal dominant or autosomal recessive SNHL in familial MD. Additionally, some novel and rare variants in other genes involved in the organization of the stereocilia links such as CDH23, PCDH15 or ADGRV1 co-segregated in the same patients. Our findings reveal a co-segregation of rare variants in the MYO7A gene and other structural myosin VIIA binding proteins involved in the tip and ankle links of the hair cell stereocilia. We suggest that recessive digenic inheritance involving these genes could affect the ultrastructure of the stereocilia links in familial MD.
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Affiliation(s)
- P Roman-Naranjo
- Otology & Neurotology Group CTS 495, Department of Genomic Medicine, Centro Pfizer-Universidad de Granada-Junta de Andalucía de Genómica e Investigación Oncológica, GENYO, Granada, Spain
| | - M D C Moleon
- Otology & Neurotology Group CTS 495, Department of Genomic Medicine, Centro Pfizer-Universidad de Granada-Junta de Andalucía de Genómica e Investigación Oncológica, GENYO, Granada, Spain; Department of Otolaryngology, Hospital Universitario Virgen de las Nieves, Instituto de Investigación Biosanitaria, ibs.GRANADA, Granada, Spain
| | - I Aran
- Department of Otolaryngology, Complexo Hospitalario de Pontevedra, Pontevedra, Spain
| | - A Escalera-Balsera
- Otology & Neurotology Group CTS 495, Department of Genomic Medicine, Centro Pfizer-Universidad de Granada-Junta de Andalucía de Genómica e Investigación Oncológica, GENYO, Granada, Spain
| | - A Soto-Varela
- Division of Otoneurology, Department of Otorhinolaryngology, Complexo Hospitalario Universitario, Santiago de Compostela, Spain
| | - D Bächinger
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland
| | - M Gomez-Fiñana
- Department of Otolaryngology, Hospital de Poniente, El Ejido, Almeria, Spain
| | - A H Eckhard
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland
| | - J A Lopez-Escamez
- Otology & Neurotology Group CTS 495, Department of Genomic Medicine, Centro Pfizer-Universidad de Granada-Junta de Andalucía de Genómica e Investigación Oncológica, GENYO, Granada, Spain; Department of Otolaryngology, Hospital Universitario Virgen de las Nieves, Instituto de Investigación Biosanitaria, ibs.GRANADA, Granada, Spain; Department of Surgery, Division of Otolaryngology, Universidad de Granada, Granada, Spain.
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7
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Naz S. Molecular genetic landscape of hereditary hearing loss in Pakistan. Hum Genet 2021; 141:633-648. [PMID: 34308486 DOI: 10.1007/s00439-021-02320-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 07/17/2021] [Indexed: 01/13/2023]
Abstract
Approximately 14.5 million Pakistani individuals have a hearing loss and half of these cases may be due to genetic causes. Though significant progress has been made in uncovering genetic variants for recessively inherited nonsyndromic deafness, Pendred syndrome, and Usher syndromes, the same is not true for dominantly inherited hearing loss, most syndromic cases and deafness with complex inheritance patterns. Variants of 57 genes have been reported to cause nonsyndromic recessive deafness in Pakistan, though most are rare. Variants of just five genes GJB2, HGF, MYO7A, SLC26A4, and TMC1 together explain 57% of profound deafness while those of GJB2, MYO15A, OTOF, SLC26A4, TMC1, and TMPRSS3 account for 47% of moderate to severe hearing loss. In contrast, although variants of at least 39 genes have been implicated in different deafness syndromes, their prevalence in the population and the spectrum of mutations have not been explored. Furthermore, research on genetics of deafness has mostly focused on individuals from the Punjab province and needs to be extended to other regions of Pakistan. Identifying the genes and their variants causing deafness in all ethnic groups is important as it will pinpoint rare as well as recurrent mutations. This information may ultimately help in offering genetic counseling and future treatments.
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Affiliation(s)
- Sadaf Naz
- School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, 54590, Pakistan.
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Whatley M, Francis A, Ng ZY, Khoh XE, Atlas MD, Dilley RJ, Wong EYM. Usher Syndrome: Genetics and Molecular Links of Hearing Loss and Directions for Therapy. Front Genet 2020; 11:565216. [PMID: 33193648 PMCID: PMC7642844 DOI: 10.3389/fgene.2020.565216] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 09/21/2020] [Indexed: 12/19/2022] Open
Abstract
Usher syndrome (USH) is an autosomal recessive (AR) disorder that permanently and severely affects the senses of hearing, vision, and balance. Three clinically distinct types of USH have been identified, decreasing in severity from Type 1 to 3, with symptoms of sensorineural hearing loss (SNHL), retinitis pigmentosa (RP), and vestibular dysfunction. There are currently nine confirmed and two suspected USH-causative genes, and a further three candidate loci have been mapped. The proteins encoded by these genes form complexes that play critical roles in the development and maintenance of cellular structures within the inner ear and retina, which have minimal capacity for repair or regeneration. In the cochlea, stereocilia are located on the apical surface of inner ear hair cells (HC) and are responsible for transducing mechanical stimuli from sound pressure waves into chemical signals. These signals are then detected by the auditory nerve fibers, transmitted to the brain and interpreted as sound. Disease-causing mutations in USH genes can destabilize the tip links that bind the stereocilia to each other, and cause defects in protein trafficking and stereocilia bundle morphology, thereby inhibiting mechanosensory transduction. This review summarizes the current knowledge on Usher syndrome with a particular emphasis on mutations in USH genes, USH protein structures, and functional analyses in animal models. Currently, there is no cure for USH. However, the genetic therapies that are rapidly developing will benefit from this compilation of detailed genetic information to identify the most effective strategies for restoring functional USH proteins.
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Affiliation(s)
- Meg Whatley
- Ear Science Institute Australia, Nedlands, WA, Australia
| | - Abbie Francis
- Ear Science Institute Australia, Nedlands, WA, Australia
- Emergency Medicine, The University of Western Australia, Nedlands, WA, Australia
| | - Zi Ying Ng
- Ear Science Institute Australia, Nedlands, WA, Australia
| | - Xin Ee Khoh
- Ear Science Institute Australia, Nedlands, WA, Australia
- School of Human Sciences, The University of Western Australia, Nedlands, WA, Australia
| | - Marcus D. Atlas
- Ear Science Institute Australia, Nedlands, WA, Australia
- Ear Sciences Centre, The University of Western Australia, Nedlands, WA, Australia
| | - Rodney J. Dilley
- Ear Science Institute Australia, Nedlands, WA, Australia
- Ear Sciences Centre, The University of Western Australia, Nedlands, WA, Australia
- Centre for Cell Therapy and Regenerative Medicine, The University of Western Australia, Perth, WA, Australia
| | - Elaine Y. M. Wong
- Ear Science Institute Australia, Nedlands, WA, Australia
- Ear Sciences Centre, The University of Western Australia, Nedlands, WA, Australia
- School of Pharmacy and Biomedical Sciences, Faculty of Health Sciences, Curtin University, Bentley, WA, Australia
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Pyott SJ, van Tuinen M, Screven LA, Schrode KM, Bai JP, Barone CM, Price SD, Lysakowski A, Sanderford M, Kumar S, Santos-Sacchi J, Lauer AM, Park TJ. Functional, Morphological, and Evolutionary Characterization of Hearing in Subterranean, Eusocial African Mole-Rats. Curr Biol 2020; 30:4329-4341.e4. [PMID: 32888484 DOI: 10.1016/j.cub.2020.08.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/09/2020] [Accepted: 08/07/2020] [Indexed: 12/26/2022]
Abstract
Naked mole-rats are highly vocal, eusocial, subterranean rodents with, counterintuitively, poor hearing. The causes underlying their altered hearing are unknown. Moreover, whether altered hearing is degenerate or adaptive to their unique lifestyles is controversial. We used various methods to identify the factors contributing to altered hearing in naked and the related Damaraland mole-rats and to examine whether these alterations result from relaxed or adaptive selection. Remarkably, we found that cochlear amplification was absent from both species despite normal prestin function in outer hair cells isolated from naked mole-rats. Instead, loss of cochlear amplification appears to result from abnormal hair bundle morphologies observed in both species. By exploiting a well-curated deafness phenotype-genotype database, we identified amino acid substitutions consistent with abnormal hair bundle morphology and reduced hearing sensitivity. Amino acid substitutions were found in unique groups of six hair bundle link proteins. Molecular evolutionary analyses revealed shifts in selection pressure at both the gene and the codon level for five of these six hair bundle link proteins. Substitutions in three of these proteins are associated exclusively with altered hearing. Altogether, our findings identify the likely mechanism of altered hearing in African mole-rats, making them the only identified mammals naturally lacking cochlear amplification. Moreover, our findings suggest that altered hearing in African mole-rats is adaptive, perhaps tailoring hearing to eusocial and subterranean lifestyles. Finally, our work reveals multiple, unique evolutionary trajectories in African mole-rat hearing and establishes species members as naturally occurring disease models to investigate human hearing loss.
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Affiliation(s)
- Sonja J Pyott
- University Medical Center Groningen and University of Groningen, Department of Otorhinolaryngology and Head/Neck Surgery, 9713GZ Groningen, the Netherlands.
| | - Marcel van Tuinen
- University Medical Center Groningen and University of Groningen, Department of Otorhinolaryngology and Head/Neck Surgery, 9713GZ Groningen, the Netherlands
| | - Laurel A Screven
- Johns Hopkins School of Medicine, Department of Otolaryngology, Baltimore, MD 21205, USA
| | - Katrina M Schrode
- Johns Hopkins School of Medicine, Department of Otolaryngology, Baltimore, MD 21205, USA
| | - Jun-Ping Bai
- Yale University School of Medicine, Department of Neurology, 333 Cedar Street, New Haven, CT 06510, USA
| | - Catherine M Barone
- University of Illinois at Chicago, Department of Biological Sciences, Chicago, IL 60612, USA
| | - Steven D Price
- University of Illinois at Chicago, Department of Anatomy and Cell Biology, Chicago, IL 60612, USA
| | - Anna Lysakowski
- University of Illinois at Chicago, Department of Anatomy and Cell Biology, Chicago, IL 60612, USA
| | - Maxwell Sanderford
- Temple University, Institute for Genomics and Evolutionary Medicine and Department of Biology, Philadelphia, PA 19122, USA
| | - Sudhir Kumar
- Temple University, Institute for Genomics and Evolutionary Medicine and Department of Biology, Philadelphia, PA 19122, USA; King Abdulaziz University, Center for Excellence in Genome Medicine and Research, Jeddah, Saudi Arabia
| | - Joseph Santos-Sacchi
- Yale University School of Medicine, Department of Surgery (Otolaryngology) and Department of Neuroscience and Cellular and Molecular Physiology, 333 Cedar Street, New Haven, CT 06510, USA
| | - Amanda M Lauer
- Johns Hopkins School of Medicine, Department of Otolaryngology, Baltimore, MD 21205, USA
| | - Thomas J Park
- University of Illinois at Chicago, Department of Biological Sciences, Chicago, IL 60612, USA
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Niggemann P, György B, Chen ZY. Genome and base editing for genetic hearing loss. Hear Res 2020; 394:107958. [PMID: 32334889 PMCID: PMC7415640 DOI: 10.1016/j.heares.2020.107958] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Revised: 03/18/2020] [Accepted: 03/31/2020] [Indexed: 12/26/2022]
Abstract
Genome editing opens up a new frontier in developing personalized therapeutic solutions. With the unprecedented advance in the discovery and engineering of gene editing nucleases, it has now become potentially feasible to therapeutically influence up to 90% of all human genetic mutations. Hearing loss is one of the most well studied fields from the genetics perspective, with more than one hundred identified deafness genes. Novel viral and non-viral vectors have been established as safe and efficient modalities to deliver transgenes into cells of the cochlea and to the vestibular system in animal models. Recent studies demonstrated proof-of-concept for therapeutic genome and base editing in the mammalian inner ear and preclinical development is ongoing. This review summarizes important advances and future challenges for this transformative therapeutic modality for genetic and non-genetic hearing loss.
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Affiliation(s)
- Philipp Niggemann
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland; Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Bence György
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland; Department of Ophthalmology, University of Basel, Basel, Switzerland.
| | - Zheng-Yi Chen
- Department of Otolaryngology-Head and Neck Surgery, Graduate Program in Speech and Hearing Bioscience and Technology and Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA; Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA, 02114, USA.
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11
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Ołdak M, Lechowicz U, Pollak A, Oziębło D, Skarżyński H. Overinterpretation of high throughput sequencing data in medical genetics: first evidence against TMPRSS3/GJB2 digenic inheritance of hearing loss. J Transl Med 2019; 17:269. [PMID: 31412945 PMCID: PMC6694500 DOI: 10.1186/s12967-019-2018-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 08/06/2019] [Indexed: 11/15/2022] Open
Abstract
Background Hearing loss (HL) is the most common disability of human senses characterized by a great allelic heterogeneity. GJB2 and TMPRSS3 are two well-known HL genes typically underlying its monogenic form. Recently, TMPRSS3/GJB2 digenic inheritance has been proposed. As results of genetic testing can be easily overinterpreted, we aimed to verify the hypothesis. Methods From genetic database of HL patients with at least one TMPRSS3 pathogenic variants we have selected individuals with additional GJB2 pathogenic variants. All of the available family members were recruited for the study. Segregation analysis of the respective TMPRSS3 and GJB2 pathogenic variants was performed within the families. Results The strategy has allowed to identify four individuals who were double heterozygous for known pathogenic TMPRSS3 and GJB2 variants. Two individuals from different families had GJB2 c.35delG and TMPRSS3 c.208delC and in two other individuals from one family GJB2 c.35delG together with TMPRSS3 c.1343T>C variants were found. None of these subjects has ever reported hearing problems and their hearing status was normal. Conclusions Our data provide evidence against TMPRSS3/GJB2 digenic inheritance of HL. As high throughput sequencing is increasingly used for genetic testing, particular caution should be taken to provide the patients with accurate genetic counseling.
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Affiliation(s)
- Monika Ołdak
- Department of Genetics, World Hearing Center, Institute of Physiology and Pathology of Hearing, M. Mochnackiego 10, 02-042, Warsaw, Poland.
| | - Urszula Lechowicz
- Department of Genetics, World Hearing Center, Institute of Physiology and Pathology of Hearing, M. Mochnackiego 10, 02-042, Warsaw, Poland
| | - Agnieszka Pollak
- Department of Genetics, World Hearing Center, Institute of Physiology and Pathology of Hearing, M. Mochnackiego 10, 02-042, Warsaw, Poland
| | - Dominika Oziębło
- Department of Genetics, World Hearing Center, Institute of Physiology and Pathology of Hearing, M. Mochnackiego 10, 02-042, Warsaw, Poland.,Postgraduate School of Molecular Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Henryk Skarżyński
- Oto-Rhino-Laryngology Surgery Clinic, Institute of Physiology and Pathology of Hearing, M. Mochnackiego 10, 02-042, Warsaw, Poland
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12
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Schrauwen I, Chakchouk I, Acharya A, Liaqat K, Irfanullah, Nickerson DA, Bamshad MJ, Shah K, Ahmad W, Leal SM. Novel digenic inheritance of PCDH15 and USH1G underlies profound non-syndromic hearing impairment. BMC MEDICAL GENETICS 2018; 19:122. [PMID: 30029624 PMCID: PMC6053831 DOI: 10.1186/s12881-018-0618-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/24/2018] [Indexed: 11/10/2022]
Abstract
BACKGROUND Digenic inheritance is the simplest model of oligenic disease. It can be observed when there is a strong epistatic interaction between two loci. For both syndromic and non-syndromic hearing impairment, several forms of digenic inheritance have been reported. METHODS We performed exome sequencing in a Pakistani family with profound non-syndromic hereditary hearing impairment to identify the genetic cause of disease. RESULTS We found that this family displays digenic inheritance for two trans heterozygous missense mutations, one in PCDH15 [p.(Arg1034His)] and another in USH1G [p.(Asp365Asn)]. Both of these genes are known to cause autosomal recessive non-syndromic hearing impairment and Usher syndrome. The protein products of PCDH15 and USH1G function together at the stereocilia tips in the hair cells and are necessary for proper mechanotransduction. Epistasis between Pcdh15 and Ush1G has been previously reported in digenic heterozygous mice. The digenic mice displayed a significant decrease in hearing compared to age-matched heterozygous animals. Until now no human examples have been reported. CONCLUSIONS The discovery of novel digenic inheritance mechanisms in hereditary hearing impairment will aid in understanding the interaction between defective proteins and further define inner ear function and its interactome.
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Affiliation(s)
- Isabelle Schrauwen
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza 700D, Houston, TX, 77030, USA
| | - Imen Chakchouk
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza 700D, Houston, TX, 77030, USA
| | - Anushree Acharya
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza 700D, Houston, TX, 77030, USA
| | - Khurram Liaqat
- Department of Biotechnology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Irfanullah
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Deborah A Nickerson
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Michael J Bamshad
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Khadim Shah
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Suzanne M Leal
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza 700D, Houston, TX, 77030, USA.
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13
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Effects of Cdh23 single nucleotide substitutions on age-related hearing loss in C57BL/6 and 129S1/Sv mice and comparisons with congenic strains. Sci Rep 2017; 7:44450. [PMID: 28287619 PMCID: PMC5347380 DOI: 10.1038/srep44450] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 02/08/2017] [Indexed: 11/11/2022] Open
Abstract
A single nucleotide variant (SNV) of the cadherin 23 gene (Cdh23c.753A), common to many inbred mouse strains, accelerates age-related hearing loss (AHL) and can worsen auditory phenotypes of other mutations. We used homologous recombination in C57BL/6 NJ (B6N) and 129S1/SvImJ (129S1) embryonic stem cells to engineer mouse strains with reciprocal single base pair substitutions (B6-Cdh23c.753A>G and 129S1-Cdh23c.753G>A). We compared ABR thresholds and cochlear pathologies of these SNV mice with those of congenic (B6.129S1-Cdh23Ahl+ and 129S1.B6-Cdh23ahl) and parental (B6N and 129S1) strain mice. Results verified the protective effect of the Cdh23c.753G allele, which prevented high frequency hearing loss in B6 mice to at least 18 months of age, and the AHL-inducing effect of the Cdh23c.753A allele, which worsened hearing loss in 129S1 mice. ABR thresholds differed between 129S-Cdh23c.753A SNV and 129S1.B6-Cdh23ahl congenic mice, and a linkage backcross involving these strains localized a Chr 10 QTL contributing to the difference. These results illustrate the large effects that strain background and congenic regions have on the hearing loss associated with Cdh23c.753alleles. Importantly, the B6-Cdh23c.753Gstrain can be used to eliminate the confounding influence of the Cdh23c.753Avariant in hearing studies of B6 mice and mutant mice on the B6 background.
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14
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Functional Analysis of the Transmembrane and Cytoplasmic Domains of Pcdh15a in Zebrafish Hair Cells. J Neurosci 2017; 37:3231-3245. [PMID: 28219986 DOI: 10.1523/jneurosci.2216-16.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 02/07/2017] [Accepted: 02/10/2017] [Indexed: 11/21/2022] Open
Abstract
Protocadherin 15 (PCDH15) is required for mechanotransduction in sensory hair cells as a component of the tip link. Isoforms of PCDH15 differ in their cytoplasmic domains (CD1, CD2, and CD3), but share the extracellular and transmembrane (TMD) domains, as well as an intracellular domain known as the common region (CR). In heterologous expression systems, both the TMD and CR of PCDH15 have been shown to interact with members of the mechanotransduction complex. The in vivo significance of these protein-protein interaction domains of PCDH15 in hair cells has not been determined. Here, we examined the localization and function of the two isoforms of zebrafish Pcdh15a (CD1 and CD3) in pcdh15a-null mutants by assessing Pcdh15a transgene-mediated rescue of auditory/vestibular behavior and hair cell morphology and activity. We found that either isoform alone was able to rescue the Pcdh15a-null phenotype and that the CD1- or CD3-specific regions were dispensable for hair bundle integrity and labeling of hair cells with FM4-64, which was used as a proxy for mechanotransduction. When either the CR or TMD domain was deleted, the mutated proteins localized to the stereocilial tips, but were unable to rescue FM4-64 labeling. Disrupting both domains led to a complete failure of Pcdh15a to localize to the hair bundle. Our findings demonstrate that the TMD and cytoplasmic CR domains are required for the in vivo function of Pcdh15a in zebrafish hair cells.SIGNIFICANCE STATEMENT Tip links transmit force to mechanotransduction channels at the tip of hair bundles in sensory hair cells. One component of tip links is Protocadherin 15 (PCDH15). Here, we demonstrate that, when transgenically expressed, either zebrafish Pcdh15a-cytodomain 1 (CD1) or Pcdh15a-CD3 can rescue the phenotype of a pcdh15a-null mutant. Even when lacking the specific regions for CD1 or CD3, truncated Pcdh15a that contains the so-called common region (CR) at the cytoplasmic/membrane interface still has the ability to rescue similar to full-length Pcdh15a. In contrast, Pcdh15a lacking the entire cytoplasmic domain is not functional. These results demonstrate that the CR plays a key role in the mechanotransduction complex in hair cells.
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15
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Morgan CP, Krey JF, Grati M, Zhao B, Fallen S, Kannan-Sundhari A, Liu XZ, Choi D, Müller U, Barr-Gillespie PG. PDZD7-MYO7A complex identified in enriched stereocilia membranes. eLife 2016; 5:e18312. [PMID: 27525485 PMCID: PMC5005036 DOI: 10.7554/elife.18312] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/14/2016] [Indexed: 12/15/2022] Open
Abstract
While more than 70 genes have been linked to deafness, most of which are expressed in mechanosensory hair cells of the inner ear, a challenge has been to link these genes into molecular pathways. One example is Myo7a (myosin VIIA), in which deafness mutations affect the development and function of the mechanically sensitive stereocilia of hair cells. We describe here a procedure for the isolation of low-abundance protein complexes from stereocilia membrane fractions. Using this procedure, combined with identification and quantitation of proteins with mass spectrometry, we demonstrate that MYO7A forms a complex with PDZD7, a paralog of USH1C and DFNB31. MYO7A and PDZD7 interact in tissue-culture cells, and co-localize to the ankle-link region of stereocilia in wild-type but not Myo7a mutant mice. Our data thus describe a new paradigm for the interrogation of low-abundance protein complexes in hair cell stereocilia and establish an unanticipated link between MYO7A and PDZD7.
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Affiliation(s)
- Clive P Morgan
- Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, United States
| | - Jocelyn F Krey
- Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, United States
| | - M'hamed Grati
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, United States
| | - Bo Zhao
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, United States
| | - Shannon Fallen
- Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, United States
| | | | - Xue Zhong Liu
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, United States
| | - Dongseok Choi
- OHSU-PSU School of Public Health, Oregon Health and Science University, Portland, United States
- Graduate School of Dentistry, Kyung Hee University, Seoul, Korea
| | - Ulrich Müller
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, United States
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, United States
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16
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Miyasaka Y, Shitara H, Suzuki S, Yoshimoto S, Seki Y, Ohshiba Y, Okumura K, Taya C, Tokano H, Kitamura K, Takada T, Hibino H, Shiroishi T, Kominami R, Yonekawa H, Kikkawa Y. Heterozygous mutation of Ush1g/Sans in mice causes early-onset progressive hearing loss, which is recovered by reconstituting the strain-specific mutation in Cdh23. Hum Mol Genet 2016; 25:2045-2059. [PMID: 26936824 DOI: 10.1093/hmg/ddw078] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 02/29/2016] [Indexed: 12/21/2022] Open
Abstract
Most clinical reports have suggested that patients with congenital profound hearing loss have recessive mutations in deafness genes, whereas dominant alleles are associated with progressive hearing loss (PHL). Jackson shaker (Ush1gjs) is a mouse model of recessive deafness that exhibits congenital profound deafness caused by the homozygous mutation of Ush1g/Sans on chromosome 11. We found that C57BL/6J-Ush1gjs/+ heterozygous mice exhibited early-onset PHL (ePHL) accompanied by progressive degeneration of stereocilia in the cochlear outer hair cells. Interestingly, ePHL did not develop in mutant mice with the C3H/HeN background, thus suggesting that other genetic factors are required for ePHL development. Therefore, we performed classical genetic analyses and found that the occurrence of ePHL in Ush1gjs/+ mice was associated with an interval in chromosome 10 that contains the cadherin 23 gene (Cdh23), which is also responsible for human deafness. To confirm this mutation effect, we generated C57BL/6J-Ush1gjs/+, Cdh23c.753A/G double-heterozygous mice by using the CRISPR/Cas9-mediated Cdh23c.753A>G knock-in method. The Cdh23c.753A/G mice harbored a one-base substitution (A for G), and the homozygous A allele caused moderate hearing loss with aging. Analyses revealed the complete recovery of ePHL and stereocilia degeneration in C57BL/6J-Ush1gjs/+ mice. These results clearly show that the development of ePHL requires at least two mutant alleles of the Ush1g and Cdh23 genes. Our results also suggest that because the SANS and CDH23 proteins form a complex in the stereocilia, the interaction between these proteins may play key roles in the maintenance of stereocilia and the prevention of ePHL.
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Affiliation(s)
- Yuki Miyasaka
- Mammalian Genetics Project, Graduate School of Medical and Dental Sciences
| | - Hiroshi Shitara
- Laboratory for Transgenic Technology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | | | - Sachi Yoshimoto
- Laboratory for Transgenic Technology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | | | - Yasuhiro Ohshiba
- Mammalian Genetics Project, Graduate School of Medical and Dental Sciences
| | - Kazuhiro Okumura
- Division of Oncogenomics, Cancer Genome Center, Chiba Cancer Center Research Institute, Chiba 260-0801, Japan
| | - Choji Taya
- Laboratory for Transgenic Technology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Hisashi Tokano
- Department of Otolaryngology, Tokyo Medical and Dental University, Tokyo 113-0034, Japan and
| | - Ken Kitamura
- Department of Otolaryngology, Tokyo Medical and Dental University, Tokyo 113-0034, Japan and
| | - Toyoyuki Takada
- Mammalian Genetics Laboratory, National Institute of Genetics, Mishima 411-8540, Japan
| | - Hiroshi Hibino
- Department of Molecular Physiology, Niigata University School of Medicine, Niigata 951-8510, Japan
| | - Toshihiko Shiroishi
- Mammalian Genetics Laboratory, National Institute of Genetics, Mishima 411-8540, Japan
| | | | - Hiromichi Yonekawa
- Laboratory for Transgenic Technology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Yoshiaki Kikkawa
- Mammalian Genetics Project, Graduate School of Medical and Dental Sciences,
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17
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Miyasaka Y, Suzuki S, Ohshiba Y, Watanabe K, Sagara Y, Yasuda SP, Matsuoka K, Shitara H, Yonekawa H, Kominami R, Kikkawa Y. Compound heterozygosity of the functionally null Cdh23(v-ngt) and hypomorphic Cdh23(ahl) alleles leads to early-onset progressive hearing loss in mice. Exp Anim 2014; 62:333-46. [PMID: 24172198 PMCID: PMC4160959 DOI: 10.1538/expanim.62.333] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The waltzer (v) mouse mutant harbors a mutation in Cadherin 23
(Cdh23) and is a model for Usher syndrome type 1D, which is
characterized by congenital deafness, vestibular dysfunction, and prepubertal onset of
progressive retinitis pigmentosa. In mice, functionally null Cdh23
mutations affect stereociliary morphogenesis and the polarity of both cochlear and
vestibular hair cells. In contrast, the murine Cdh23ahl
allele, which harbors a hypomorphic mutation, causes an increase in susceptibility to
age-related hearing loss in many inbred strains. We produced congenic mice by crossing
mice carrying the v niigata (Cdh23v-ngt) null
allele with mice carrying the hypomorphic Cdh23ahl allele on
the C57BL/6J background, and we then analyzed the animals’ balance and hearing phenotypes.
Although the
Cdh23v-ngt/ahl
compound heterozygous mice exhibited normal vestibular function, their hearing ability was
abnormal: the mice exhibited higher thresholds of auditory brainstem response (ABR) and
rapid age-dependent elevation of ABR thresholds compared with
Cdh23ahl/ahl
homozygous mice. We found that the stereocilia developed normally but were progressively
disrupted in
Cdh23v-ngt/ahl mice.
In hair cells, CDH23 localizes to the tip links of stereocilia, which are thought to gate
the mechanoelectrical transduction channels in hair cells. We hypothesize that the
reduction of Cdh23 gene dosage in
Cdh23v-ngt/ahl mice
leads to the degeneration of stereocilia, which consequently reduces tip link tension.
These findings indicate that CDH23 plays an important role in the maintenance of tip links
during the aging process.
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Affiliation(s)
- Yuki Miyasaka
- Mammalian Genetics Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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18
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Au A, Stuyt JG, Chen D, Alagramam K. Ups and downs of Viagra: revisiting ototoxicity in the mouse model. PLoS One 2013; 8:e79226. [PMID: 24244454 PMCID: PMC3828335 DOI: 10.1371/journal.pone.0079226] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 09/24/2013] [Indexed: 01/08/2023] Open
Abstract
Sildenafil citrate (Viagra), a phosphodiesterase 5 inhibitor (PDE5i), is a commonly prescribed drug for erectile dysfunction. Since the introduction of Viagra in 1997, several case reports have linked Viagra to sudden sensorineural hearing loss. However, these studies are not well controlled for confounding factors, such as age and noise-induced hearing loss and none of these reports are based on prospective double-blind studies. Further, animal studies report contradictory data. For example, one study (2008) reported hearing loss in rats after long-term and high-dose exposure to sildenafil citrate. The other study (2012) showed vardenafil, another formulation of PDE5i, to be protective against noise-induced hearing loss in mice and rats. Whether or not clinically relevant doses of sildenafil citrate cause hearing loss in normal subjects (animals or humans) is controversial. One possibility is that PDE5i exacerbates age-related susceptibility to hearing loss in adults. Therefore, we tested sildenafil citrate in C57BL/6J, a strain of mice that displays increased susceptibility to age-related hearing loss, and compared the results to those obtained from the FVB/N, a strain of mice with no predisposition to hearing loss. Six-week-old mice were injected with the maximum tolerated dose of sildenafil citrate (10 mg/kg/day) or saline for 30 days. Auditory brainstem responses (ABRs) were recorded pre- and post injection time points to assess hearing loss. Entry of sildenafil citrate in the mouse cochlea was confirmed by qRT-PCR analysis of a downstream target of the cGMP-PKG cascade. ABR data indicated no statistically significant difference in hearing between treated and untreated mice in both backgrounds. Results show that the maximum tolerated dose of sildenafil citrate administered daily for 4 weeks does not affect hearing in the mouse. Our study gives no indication that Viagra will negatively impact hearing and it emphasizes the need to revisit the issue of Viagra related ototoxicity in humans.
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Affiliation(s)
- Adrian Au
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - John Gerka Stuyt
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Daniel Chen
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Kumar Alagramam
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
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Ben-Salem S, Rehm HL, Willems PJ, Tamimi ZA, Ayadi H, Ali BR, Al-Gazali L. Analysis of two Arab families reveals additional support for a DFNB2 nonsyndromic phenotype of MYO7A. Mol Biol Rep 2013; 41:193-200. [PMID: 24194196 DOI: 10.1007/s11033-013-2851-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 10/29/2013] [Indexed: 02/05/2023]
Abstract
Variants in the head and tail domains of the MYO7A gene, encoding myosin VIIA, cause Usher syndrome type 1B (USH1B) and nonsyndromic deafness (DFNB2, DFNA11). In order to identify the genetic defect(s) underling profound deafness in two consanguineous Arab families living in UAE, we have sequenced a panel of 19 genes involved in Usher syndrome and nonsyndromic deafness in the index cases of the two families. This analysis revealed a novel homozygous insertion of AG (c.1952_1953insAG/p.C652fsX11) in exon 17 of the MYO7A gene in an Iraqi family, and a homozygous point mutation (c.5660C>T/p.P1887L) in exon 41 affecting the same gene in a large Palestinian family. Moreover, some individuals from the Palestinian family also harbored a novel heterozygous truncating variant (c.1267C>T/p.R423X) in the DFNB31 gene, which is involved in autosomal recessive nonsyndromic deafness type DFNB31 and Usher syndrome type II. Assuming an autosomal recessive mode of inheritance in the two inbred families, we conclude that the homozygous variants in the MYO7A gene are the disease-causing mutations in these families. Furthermore, given the absence of retinal disease in all affected patients examined, particularly a 28 year old patient, suggests that at least one family may segregate a DFNB2 presentation rather than USH1B. This finding further supports the premise that the MYO7A gene is responsible for two distinct diseases and gives evidence that the p.P1887L mutation in a homozygous state may be responsible for nonsyndromic hearing loss.
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Affiliation(s)
- Salma Ben-Salem
- Department of Pathology, College of Medicine and Heath Sciences, United Arab Emirates University, Al Ain, United Arab Emirates,
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20
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Novel myosin mutations for hereditary hearing loss revealed by targeted genomic capture and massively parallel sequencing. Eur J Hum Genet 2013; 22:768-75. [PMID: 24105371 DOI: 10.1038/ejhg.2013.232] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Revised: 08/15/2013] [Accepted: 08/29/2013] [Indexed: 11/08/2022] Open
Abstract
Hereditary hearing loss is genetically heterogeneous, with a large number of genes and mutations contributing to this sensory, often monogenic, disease. This number, as well as large size, precludes comprehensive genetic diagnosis of all known deafness genes. A combination of targeted genomic capture and massively parallel sequencing (MPS), also referred to as next-generation sequencing, was applied to determine the deafness-causing genes in hearing-impaired individuals from Israeli Jewish and Palestinian Arab families. Among the mutations detected, we identified nine novel mutations in the genes encoding myosin VI, myosin VIIA and myosin XVA, doubling the number of myosin mutations in the Middle East. Myosin VI mutations were identified in this population for the first time. Modeling of the mutations provided predicted mechanisms for the damage they inflict in the molecular motors, leading to impaired function and thus deafness. The myosin mutations span all regions of these molecular motors, leading to a wide range of hearing phenotypes, reinforcing the key role of this family of proteins in auditory function. This study demonstrates that multiple mutations responsible for hearing loss can be identified in a relatively straightforward manner by targeted-gene MPS technology and concludes that this is the optimal genetic diagnostic approach for identification of mutations responsible for hearing loss.
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Abstract
Digenic inheritance (DI) is the simplest form of inheritance for genetically complex diseases. By contrast with the thousands of reports that mutations in single genes cause human diseases, there are only dozens of human disease phenotypes with evidence for DI in some pedigrees. The advent of high-throughput sequencing (HTS) has made it simpler to identify monogenic disease causes and could similarly simplify proving DI because one can simultaneously find mutations in two genes in the same sample. However, through 2012, I could find only one example of human DI in which HTS was used; in that example, HTS found only the second of the two genes. To explore the gap between expectation and reality, I tried to collect all examples of human DI with a narrow definition and characterise them according to the types of evidence collected, and whether there has been replication. Two strong trends are that knowledge of candidate genes and knowledge of protein–protein interactions (PPIs) have been helpful in most published examples of human DI. By contrast, the positional method of genetic linkage analysis, has been mostly unsuccessful in identifying genes underlying human DI. Based on the empirical data, I suggest that combining HTS with growing networks of established PPIs may expedite future discoveries of human DI and strengthen the evidence for them.
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22
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Han F, Yu H, Zheng T, Ma X, Zhao X, Li P, Le L, Su Y, Zheng QY. Otoprotective effects of erythropoietin on Cdh23erl/erl mice. Neuroscience 2013; 237:1-6. [PMID: 23384607 DOI: 10.1016/j.neuroscience.2013.01.052] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 01/18/2013] [Accepted: 01/24/2013] [Indexed: 11/30/2022]
Abstract
The Cdh23(erl/erl) mice are a novel mouse model for DFNB12 and are characterized by progressive hearing loss. In this study, erythropoietin (EPO) was given to the Cdh23(erl/erl) mice by intraperitoneal injection every other day from P7 for 7 weeks. Phosphate-buffered saline-treated or untreated Cdh23(erl/erl) mice were used as controls. Auditory-evoked brainstem response (ABR) thresholds and distortion product oto-acoustic emission (DPOAE) were measured in the mouse groups at the age of 4, 6 and 8 weeks. The results show that EPO can significantly decrease the ABR thresholds in the Cdh23(erl/erl) mice as compared with those of the untreated mice at stimulus frequencies of click, 8-, 16- and 32-kHz at three time points. Meanwhile, DPOAE amplitudes in the EPO-treated Cdh23(erl/erl) mouse group were significantly higher than those of the untreated groups at f2 frequency of 15383 Hz at the three time points. Furthermore, the mean percentage of outer hair cell loss at middle through basal turns of cochleae was significantly lower in EPO-treated Cdh23(erl/erl) mice than in the untreated mice (P<0.05). This is the first report that EPO acts as an otoprotectant in a DFNB12 mouse model with progressive hearing loss.
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Affiliation(s)
- F Han
- Transformative Otology and Neuroscience Center, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China
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