101
|
Fettiplace R, Kim KX. The physiology of mechanoelectrical transduction channels in hearing. Physiol Rev 2014; 94:951-86. [PMID: 24987009 DOI: 10.1152/physrev.00038.2013] [Citation(s) in RCA: 178] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Much is known about the mechanotransducer (MT) channels mediating transduction in hair cells of the vertrbrate inner ear. With the use of isolated preparations, it is experimentally feasible to deliver precise mechanical stimuli to individual cells and record the ensuing transducer currents. This approach has shown that small (1-100 nm) deflections of the hair-cell stereociliary bundle are transmitted via interciliary tip links to open MT channels at the tops of the stereocilia. These channels are cation-permeable with a high selectivity for Ca(2+); two channels are thought to be localized at the lower end of the tip link, each with a large single-channel conductance that increases from the low- to high-frequency end of the cochlea. Ca(2+) influx through open channels regulates their resting open probability, which may contribute to setting the hair cell resting potential in vivo. Ca(2+) also controls transducer fast adaptation and force generation by the hair bundle, the two coupled processes increasing in speed from cochlear apex to base. The molecular intricacy of the stereocilary bundle and the transduction apparatus is reflected by the large number of single-gene mutations that are linked to sensorineural deafness, especially those in Usher syndrome. Studies of such mutants have led to the discovery of many of the molecules of the transduction complex, including the tip link and its attachments to the stereociliary core. However, the MT channel protein is still not firmly identified, nor is it known whether the channel is activated by force delivered through accessory proteins or by deformation of the lipid bilayer.
Collapse
Affiliation(s)
- Robert Fettiplace
- Department of Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin
| | - Kyunghee X Kim
- Department of Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin
| |
Collapse
|
102
|
Abstract
Uniquely among human senses, hearing is not simply a passive response to stimulation. Our auditory system is instead enhanced by an active process in cochlear hair cells that amplifies acoustic signals several hundred-fold, sharpens frequency selectivity and broadens the ear's dynamic range. Active motility of the mechanoreceptive hair bundles underlies the active process in amphibians and some reptiles; in mammals, this mechanism operates in conjunction with prestin-based somatic motility. Both individual hair bundles and the cochlea as a whole operate near a dynamical instability, the Hopf bifurcation, which accounts for the cardinal features of the active process.
Collapse
|
103
|
Bokolia NP, Mishra M. Hearing molecules, mechanism and transportation: modeled in Drosophila melanogaster. Dev Neurobiol 2014; 75:109-30. [PMID: 25081222 DOI: 10.1002/dneu.22221] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/29/2014] [Accepted: 07/29/2014] [Indexed: 01/19/2023]
Abstract
Mechanosensory transduction underlies the perception of touch, sound and acceleration. The mechanical signals exist in the environment are resensed by the specialized mechanosensory cells, which convert the external forces into the electrical signals. Hearing is a magnificent example that relies on the mechanotransduction mediated by the auditory cells, for example the inner-ear hair cells in vertebrates and the Johnston's organ (JO) in fly. Previous studies have shown the fundamental physiological processes in the fly and vertebrate auditory organs are similar, suggesting that there might be a set of similar molecules underlying these processes. The molecular studies of the fly JO have been shown to be remarkably successful in discovering the developmental and functional genes that provided further implications in vertebrates. Several evolutionarily conserved molecules and signaling pathways have been shown to govern the development of the auditory organs in both vertebrates and invertebrates. The current review describes the similarities and differences between the vertebrate and fly auditory organs at developmental, structural, molecular, and transportation levels.
Collapse
Affiliation(s)
- Naveen Prakash Bokolia
- Department of Life Science, National Institute of Technology Rourkela, Rourkela, Orissa, India
| | | |
Collapse
|
104
|
FAM65B is a membrane-associated protein of hair cell stereocilia required for hearing. Proc Natl Acad Sci U S A 2014; 111:9864-8. [PMID: 24958875 DOI: 10.1073/pnas.1401950111] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In a large consanguineous Turkish kindred with recessive nonsyndromic, prelingual, profound hearing loss, we identified in the gene FAM65B (MIM611410) a splice site mutation (c.102-1G>A) that perfectly cosegregates with the phenotype in the family. The mutation leads to exon skipping and deletion of 52-amino acid residues of a PX membrane localization domain. FAM65B is known to be involved in myotube formation and in regulation of cell adhesion, polarization, and migration. We show that wild-type Fam65b is expressed during embryonic and postnatal development stages in murine cochlea, and that the protein localizes to the plasma membranes of the stereocilia of inner and outer hair cells of the inner ear. The wild-type protein targets the plasma membrane, whereas the mutant protein accumulates in cytoplasmic inclusion bodies and does not reach the membrane. In zebrafish, knockdown of fam65b leads to significant reduction of numbers of saccular hair cells and neuromasts and to hearing loss. We conclude that FAM65B is a plasma membrane-associated protein of hair cell stereocilia that is essential for hearing.
Collapse
|
105
|
Krawitz PM, Schiska D, Krüger U, Appelt S, Heinrich V, Parkhomchuk D, Timmermann B, Millan JM, Robinson PN, Mundlos S, Hecht J, Gross M. Screening for single nucleotide variants, small indels and exon deletions with a next-generation sequencing based gene panel approach for Usher syndrome. Mol Genet Genomic Med 2014; 2:393-401. [PMID: 25333064 PMCID: PMC4190874 DOI: 10.1002/mgg3.92] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 05/13/2014] [Accepted: 05/13/2014] [Indexed: 12/11/2022] Open
Abstract
Usher syndrome is an autosomal recessive disorder characterized both by deafness and blindness. For the three clinical subtypes of Usher syndrome causal mutations in altogether 12 genes and a modifier gene have been identified. Due to the genetic heterogeneity of Usher syndrome, the molecular analysis is predestined for a comprehensive and parallelized analysis of all known genes by next-generation sequencing (NGS) approaches. We describe here the targeted enrichment and deep sequencing for exons of Usher genes and compare the costs and workload of this approach compared to Sanger sequencing. We also present a bioinformatics analysis pipeline that allows us to detect single-nucleotide variants, short insertions and deletions, as well as copy number variations of one or more exons on the same sequence data. Additionally, we present a flexible in silico gene panel for the analysis of sequence variants, in which newly identified genes can easily be included. We applied this approach to a cohort of 44 Usher patients and detected biallelic pathogenic mutations in 35 individuals and monoallelic mutations in eight individuals of our cohort. Thirty-nine of the sequence variants, including two heterozygous deletions comprising several exons of USH2A, have not been reported so far. Our NGS-based approach allowed us to assess single-nucleotide variants, small indels, and whole exon deletions in a single test. The described diagnostic approach is fast and cost-effective with a high molecular diagnostic yield.
Collapse
Affiliation(s)
- Peter M Krawitz
- Institute for Medical Genetics and Human Genetics, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Daniela Schiska
- Department of Audiology and Phoniatrics, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Ulrike Krüger
- Institute for Medical Genetics and Human Genetics, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Sandra Appelt
- Institute for Medical Genetics and Human Genetics, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Verena Heinrich
- Institute for Medical Genetics and Human Genetics, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Dmitri Parkhomchuk
- Institute for Medical Genetics and Human Genetics, Charité Universitätsmedizin Berlin Berlin, Germany
| | | | - Jose M Millan
- Unidad de Genetica, Hospital Universitario La Fe and CIBERER Valencia, Spain
| | - Peter N Robinson
- Institute for Medical Genetics and Human Genetics, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Stefan Mundlos
- Institute for Medical Genetics and Human Genetics, Charité Universitätsmedizin Berlin Berlin, Germany
| | - Jochen Hecht
- Berlin Brandenburg Center for Regenerative Therapies BCRT Berlin, Germany
| | - Manfred Gross
- Department of Audiology and Phoniatrics, Charité Universitätsmedizin Berlin Berlin, Germany
| |
Collapse
|
106
|
Kim HJ, Ryu J, Woo HM, Cho SS, Sung MK, Kim SC, Park MH, Park T, Koo SK. Patterns of gene expression associated with Pten deficiency in the developing inner ear. PLoS One 2014; 9:e97544. [PMID: 24893171 PMCID: PMC4043736 DOI: 10.1371/journal.pone.0097544] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 04/19/2014] [Indexed: 12/26/2022] Open
Abstract
In inner ear development, phosphatase and tensin homolog (PTEN) is necessary for neuronal maintenance, such as neuronal survival and accurate nerve innervations of hair cells. We previously reported that Pten conditional knockout (cKO) mice exhibited disorganized fasciculus with neuronal apoptosis in spiral ganglion neurons (SGNs). To better understand the genes and signaling networks related to auditory neuron maintenance, we compared the profiles of differentially expressed genes (DEGs) using microarray analysis of the inner ear in E14.5 Pten cKO and wild-type mice. We identified 46 statistically significant transcripts using significance analysis of microarrays, with the false-discovery rate set at 0%. Among the DEGs, expression levels of candidate genes and expression domains were validated by quantitative real-time RT-PCR and in situ hybridization, respectively. Ingenuity pathway analysis using DEGs identified significant signaling networks associated with apoptosis, cellular movement, and axon guidance (i.e., secreted phosphoprotein 1 (Spp1)-mediated cellular movement and regulator of G-protein signaling 4 (Rgs4)-mediated axon guidance). This result was consistent with the phenotypic defects of SGNs in Pten cKO mice (e.g., neuronal apoptosis, abnormal migration, and irregular nerve fiber patterns of SGNs). From this study, we suggest two key regulatory signaling networks mediated by Spp1 and Rgs4, which may play potential roles in neuronal differentiation of developing auditory neurons.
Collapse
Affiliation(s)
- Hyung Jin Kim
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
| | - Jihee Ryu
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
| | - Hae-Mi Woo
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
| | - Samuel Sunghwan Cho
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, South Korea
| | - Min Kyung Sung
- Korean BioInformation Center (KOBIC), Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
| | - Sang Cheol Kim
- Korean BioInformation Center (KOBIC), Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
| | - Mi-Hyun Park
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
| | - Taesung Park
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, South Korea
- Department of Statistics, Seoul National University, Seoul, South Korea
| | - Soo Kyung Koo
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
- * E-mail:
| |
Collapse
|
107
|
Nakanishi H, Kurima K, Kawashima Y, Griffith AJ. Mutations of TMC1 cause deafness by disrupting mechanoelectrical transduction. Auris Nasus Larynx 2014; 41:399-408. [PMID: 24933710 DOI: 10.1016/j.anl.2014.04.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 04/22/2014] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Mutations of transmembrane channel-like 1 gene (TMC1) can cause dominant (DFNA36) or recessive (DFNB7/B11) deafness. In this article, we describe the characteristics of DFNA36 and DFNB7/B11 deafness, the features of the Tmc1 mutant mouse strains, and recent advances in our understanding of TMC1 function. METHODS Publications related to TMC1, DFNA36, or DFNB7/B11 were identified through PubMed. RESULTS All affected DFNA36 subjects showed post-lingual, progressive, sensorineural hearing loss (HL), initially affecting high frequencies. In contrast, almost all affected DFNB7/B11 subjects demonstrated congenital or prelingual severe to profound sensorineural HL. The mouse Tmc1 gene also has dominant and recessive mutant alleles that cause HL in mutant strains, including Beethoven, deafness, and Tmc1 knockout mice. These mutant mice have been instrumental for revealing that Tmc1 and its closely related paralog Tmc2 are expressed in cochlear and vestibular hair cells, and are required for hair cell mechanoelectrical transduction (MET). Recent studies suggest that TMC1 and TMC2 may be components of the long-sought hair cell MET channel. CONCLUSION TMC1 mutations disrupt hair cell MET.
Collapse
Affiliation(s)
- Hiroshi Nakanishi
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 35A Convent Dr, Bethesda, MD 20892, USA
| | - Kiyoto Kurima
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 35A Convent Dr, Bethesda, MD 20892, USA
| | - Yoshiyuki Kawashima
- Department of Otolaryngology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Andrew J Griffith
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 35A Convent Dr, Bethesda, MD 20892, USA.
| |
Collapse
|
108
|
Wasfy MM, Matsui JI, Miller J, Dowling JE, Perkins BD. myosin 7aa(-/-) mutant zebrafish show mild photoreceptor degeneration and reduced electroretinographic responses. Exp Eye Res 2014; 122:65-76. [PMID: 24698764 DOI: 10.1016/j.exer.2014.03.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 03/18/2014] [Accepted: 03/19/2014] [Indexed: 01/20/2023]
Abstract
Mutations in myosin VIIa (MYO7A) cause Usher Syndrome 1B (USH1B), a disease characterized by the combination of sensorineural hearing loss and visual impairment termed retinitis pigmentosa (RP). Although the shaker-1 mouse model of USH1B exists, only minor defects in the retina have been observed during its lifespan. Previous studies of the zebrafish mariner mutant, which also carries a mutation in myo7aa, revealed balance and hearing defects in the mutants but the retinal phenotype has not been described. We found elevated cell death in the outer nuclear layer (ONL) of myo7aa(-/-) mutants. While myo7aa(-/-) mutants retained visual behaviors in the optokinetic reflex (OKR) assay, electroretinogram (ERG) recordings revealed a significant decrease in both a- and b-wave amplitudes in mutant animals, but not a change in ERG threshold sensitivity. Immunohistochemistry showed mislocalization of rod and blue cone opsins and reduced expression of rod-specific markers in the myo7aa(-/-) ONL, providing further evidence that the photoreceptor degeneration observed represents the initial stages of the RP. Further, constant light exposure resulted in widespread photoreceptor degeneration and the appearance of large holes in the retinal pigment epithelium (RPE). No differences were observed in the retinomotor movements of the photoreceptors or in melanosome migration within the RPE, suggesting that myo7aa(-/-) does not function in these processes in teleosts. These results indicate that the zebrafish myo7aa(-/-) mutant is a useful animal model for the RP seen in humans with USH1B.
Collapse
Affiliation(s)
- Meagan M Wasfy
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Jonathan I Matsui
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Jessica Miller
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - John E Dowling
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Brian D Perkins
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
| |
Collapse
|
109
|
The retinal phenotype of Usher syndrome: pathophysiological insights from animal models. C R Biol 2014; 337:167-77. [PMID: 24702843 DOI: 10.1016/j.crvi.2013.12.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 12/03/2013] [Indexed: 01/26/2023]
Abstract
The Usher syndrome (USH) is the most prevalent cause of inherited deaf-blindness. Three clinical subtypes, USH1-3, have been defined, and ten USH genes identified. The hearing impairment due to USH gene defects has been shown to result from improper organisation of the hair bundle, the sound receptive structure of sensory hair cells. In contrast, the cellular basis of the visual defect is less well understood as this phenotype is absent in almost all the USH mouse models that faithfully mimic the human hearing impairment. Structural and molecular interspecies discrepancies regarding photoreceptor calyceal processes and the association with the distribution of USH1 proteins have recently been unravelled, and have led to the conclusion that a defect in the USH1 protein complex-mediated connection between the photoreceptor outer segment and the surrounding calyceal processes (in both rods and cones), and the inner segment (in rods only), probably causes the USH1 retinal dystrophy in humans.
Collapse
|
110
|
Sensational placodes: neurogenesis in the otic and olfactory systems. Dev Biol 2014; 389:50-67. [PMID: 24508480 PMCID: PMC3988839 DOI: 10.1016/j.ydbio.2014.01.023] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 01/27/2014] [Accepted: 01/28/2014] [Indexed: 11/22/2022]
Abstract
For both the intricate morphogenetic layout of the sensory cells in the ear and the elegantly radial arrangement of the sensory neurons in the nose, numerous signaling molecules and genetic determinants are required in concert to generate these specialized neuronal populations that help connect us to our environment. In this review, we outline many of the proteins and pathways that play essential roles in the differentiation of otic and olfactory neurons and their integration into their non-neuronal support structures. In both cases, well-known signaling pathways together with region-specific factors transform thickened ectodermal placodes into complex sense organs containing numerous, diverse neuronal subtypes. Olfactory and otic placodes, in combination with migratory neural crest stem cells, generate highly specialized subtypes of neuronal cells that sense sound, position and movement in space, odors and pheromones throughout our lives.
Collapse
|
111
|
Zheng L, Beeler DM, Bartles JR. Characterization and regulation of an additional actin-filament-binding site in large isoforms of the stereocilia actin-bundling protein espin. J Cell Sci 2014; 127:1306-17. [PMID: 24424026 PMCID: PMC3953818 DOI: 10.1242/jcs.143255] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The espin actin-bundling proteins, which are produced as isoforms of different sizes from a single gene, are required for the growth of hair cell stereocilia. We have characterized an additional actin-filament-binding site present in the extended amino-termini of large espin isoforms. Constitutively active in espin 2, the site increased the size of actin bundles formed in vitro and inhibited actin fluorescence recovery in microvilli. In espin 1, which has an N-terminal ankyrin repeat domain, the site was autoinhibited by binding between the ankyrin repeat domain and a peptide near the actin-binding site. Deletion of this peptide from espin 1 activated its actin-binding site. The peptide resembled tail homology domain I of myosin III, a ligand of the ankyrin repeat domain localized with espin 1 at the tip of stereocilia. A myosin III tail homology domain I peptide, but not scrambled control peptides, inhibited internal binding of the ankyrin repeat domain and released the espin 1 actin-binding site from autoinhibition. Thus, this regulation could result in local activation of the additional actin-binding site of espin 1 by myosin III in stereocilia.
Collapse
Affiliation(s)
- Lili Zheng
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611 USA
| | | | | |
Collapse
|
112
|
Rehman AU, Santos-Cortez RLP, Morell RJ, Drummond MC, Ito T, Lee K, Khan AA, Basra MAR, Wasif N, Ayub M, Ali RA, Raza SI, Nickerson DA, Shendure J, Bamshad M, Riazuddin S, Billington N, Khan SN, Friedman PL, Griffith AJ, Ahmad W, Riazuddin S, Leal SM, Friedman TB. Mutations in TBC1D24, a gene associated with epilepsy, also cause nonsyndromic deafness DFNB86. Am J Hum Genet 2014; 94:144-52. [PMID: 24387994 DOI: 10.1016/j.ajhg.2013.12.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 12/06/2013] [Indexed: 01/12/2023] Open
Abstract
Inherited deafness is clinically and genetically heterogeneous. We recently mapped DFNB86, a locus associated with nonsyndromic deafness, to chromosome 16p. In this study, whole-exome sequencing was performed with genomic DNA from affected individuals from three large consanguineous families in which markers linked to DFNB86 segregate with profound deafness. Analyses of these data revealed homozygous mutation c.208G>T (p.Asp70Tyr) or c.878G>C (p.Arg293Pro) in TBC1D24 as the underlying cause of deafness in the three families. Sanger sequence analysis of TBC1D24 in an additional large family in which deafness segregates with DFNB86 identified the c.208G>T (p.Asp70Tyr) substitution. These mutations affect TBC1D24 amino acid residues that are conserved in orthologs ranging from fruit fly to human. Neither variant was observed in databases of single-nucleotide variants or in 634 chromosomes from ethnically matched control subjects. TBC1D24 in the mouse inner ear was immunolocalized predominantly to spiral ganglion neurons, indicating that DFNB86 deafness might be an auditory neuropathy spectrum disorder. Previously, six recessive mutations in TBC1D24 were reported to cause seizures (hearing loss was not reported) ranging in severity from epilepsy with otherwise normal development to epileptic encephalopathy resulting in childhood death. Two of our four families in which deafness segregates with mutant alleles of TBC1D24 were available for neurological examination. Cosegregation of epilepsy and deafness was not observed in these two families. Although the causal relationship between genotype and phenotype is not presently understood, our findings, combined with published data, indicate that recessive alleles of TBC1D24 can cause either epilepsy or nonsyndromic deafness.
Collapse
Affiliation(s)
- Atteeq U Rehman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA
| | - Regie Lyn P Santos-Cortez
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Robert J Morell
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA
| | - Meghan C Drummond
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA
| | - Taku Ito
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA
| | - Kwanghyuk Lee
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Asma A Khan
- Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54500, Pakistan
| | - Muhammad Asim R Basra
- Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54500, Pakistan
| | - Naveed Wasif
- Center for Research in Molecular Medicine, Institute of Molecular Biology and Biotechnology, The University of Lahore, Lahore 54000, Pakistan
| | - Muhammad Ayub
- Institute of Biochemistry, University of Baluchistan, Quetta 87300, Pakistan
| | - Rana A Ali
- Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54500, Pakistan
| | - Syed I Raza
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad 45320, Pakistan
| | - Deborah A Nickerson
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Michael Bamshad
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Saima Riazuddin
- Division of Pediatric Otolaryngology - Head and Neck Surgery, Cincinnati Children's Research Foundation, Cincinnati, OH 45229 USA; Department of Otolaryngology - Head and Neck Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Neil Billington
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shaheen N Khan
- Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54500, Pakistan
| | | | - Andrew J Griffith
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad 45320, Pakistan
| | - Sheikh Riazuddin
- Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54500, Pakistan; Allama Iqbal Medical College and Jinnah Hospital Complex, University of Health Sciences, Lahore 54550, Pakistan
| | - Suzanne M Leal
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA.
| |
Collapse
|
113
|
|
114
|
A molecular blueprint at the apical surface establishes planar asymmetry in cochlear hair cells. Dev Cell 2013; 27:88-102. [PMID: 24135232 DOI: 10.1016/j.devcel.2013.09.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 08/29/2013] [Accepted: 09/13/2013] [Indexed: 11/22/2022]
Abstract
Sound perception relies on the planar polarization of the mechanosensory hair cell apex, which develops a V-shaped stereocilia bundle pointing toward an eccentric kinocilium. It remains unknown how intrinsically asymmetric bundles arise and are concomitantly oriented in the tissue. We report here that mInsc, LGN, and Gαi proteins, which classically regulate mitotic spindle orientation, are polarized in a lateral microvilli-free region, or "bare zone," at the apical hair cell surface. By creating and extending the bare zone, these proteins trigger a relocalization of the eccentric kinocilium midway toward the cell center. aPKC is restrained medially by mInsc/LGN/Gαi, resulting in compartmentalization of the apical surface that imparts the V-shaped distribution of stereocilia and brings the asymmetric bundle in register with the relocalized kinocilium. Gαi is additionally required for lateral orientation of cochlear hair cells, providing a possible mechanism to couple the emergence of asymmetric stereocilia bundles with planar cell polarity.
Collapse
|
115
|
Salles FT, Andrade LR, Tanda S, Grati M, Plona KL, Gagnon LH, Johnson KR, Kachar B, Berryman MA. CLIC5 stabilizes membrane-actin filament linkages at the base of hair cell stereocilia in a molecular complex with radixin, taperin, and myosin VI. Cytoskeleton (Hoboken) 2013; 71:61-78. [PMID: 24285636 DOI: 10.1002/cm.21159] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 11/22/2013] [Accepted: 11/25/2013] [Indexed: 12/30/2022]
Abstract
Chloride intracellular channel 5 protein (CLIC5) was originally isolated from microvilli in complex with actin binding proteins including ezrin, a member of the Ezrin-Radixin-Moesin (ERM) family of membrane-cytoskeletal linkers. CLIC5 concentrates at the base of hair cell stereocilia and is required for normal hearing and balance in mice, but its functional significance is poorly understood. This study investigated the role of CLIC5 in postnatal development and maintenance of hair bundles. Confocal and scanning electron microscopy of CLIC5-deficient jitterbug (jbg) mice revealed progressive fusion of stereocilia as early as postnatal day 10. Radixin (RDX), protein tyrosine phosphatase receptor Q (PTPRQ), and taperin (TPRN), deafness-associated proteins that also concentrate at the base of stereocilia, were mislocalized in fused stereocilia of jbg mice. TPRQ and RDX were dispersed even prior to stereocilia fusion. Biochemical assays showed interaction of CLIC5 with ERM proteins, TPRN, and possibly myosin VI (MYO6). In addition, CLIC5 and RDX failed to localize normally in fused stereocilia of MYO6 mutant mice. Based on these findings, we propose a model in which these proteins work together as a complex to stabilize linkages between the plasma membrane and subjacent actin cytoskeleton at the base of stereocilia.
Collapse
Affiliation(s)
- Felipe T Salles
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland
| | | | | | | | | | | | | | | | | |
Collapse
|
116
|
Kluth S, Distl O. Congenital sensorineural deafness in dalmatian dogs associated with quantitative trait loci. PLoS One 2013; 8:e80642. [PMID: 24324618 PMCID: PMC3851758 DOI: 10.1371/journal.pone.0080642] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 10/14/2013] [Indexed: 12/13/2022] Open
Abstract
A genome-wide association study (GWAS) was performed for 235 Dalmatian dogs using the canine Illumina high density bead chip to identify quantitative trait loci (QTL) associated with canine congenital sensorineural deafness (CCSD). Data analysis was performed for all Dalmatian dogs and in addition, separately for brown-eyed and blue-eyed dogs because of the significant influence of eye colour on CCSD in Dalmatian dogs. Mixed linear model analysis (MLM) revealed seven QTL with experiment-wide significant associations (-log10P>5.0) for CCSD in all Dalmatian dogs. Six QTL with experiment-wide significant associations for CCSD were found in brown-eyed Dalmatian dogs and in blue-eyed Dalmatian dogs, four experiment-wide significant QTL were detected. The experiment-wide CCSD-associated SNPs explained 82% of the phenotypic variance of CCSD. Five CCSD-loci on dog chromosomes (CFA) 6, 14, 27, 29 and 31 were in close vicinity of genes shown as causative for hearing loss in human and/or mouse.
Collapse
Affiliation(s)
- Susanne Kluth
- Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Ottmar Distl
- Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Hannover, Germany
| |
Collapse
|
117
|
Salvatore S, Fishman GA, Genead MA. Treatment of cystic macular lesions in hereditary retinal dystrophies. Surv Ophthalmol 2013; 58:560-84. [DOI: 10.1016/j.survophthal.2012.11.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 11/14/2012] [Accepted: 11/20/2012] [Indexed: 12/25/2022]
|
118
|
An alteration in ELMOD3, an Arl2 GTPase-activating protein, is associated with hearing impairment in humans. PLoS Genet 2013; 9:e1003774. [PMID: 24039609 PMCID: PMC3764207 DOI: 10.1371/journal.pgen.1003774] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 07/24/2013] [Indexed: 12/30/2022] Open
Abstract
Exome sequencing coupled with homozygosity mapping was used to identify a transition mutation (c.794T>C; p.Leu265Ser) in ELMOD3 at the DFNB88 locus that is associated with nonsyndromic deafness in a large Pakistani family, PKDF468. The affected individuals of this family exhibited pre-lingual, severe-to-profound degrees of mixed hearing loss. ELMOD3 belongs to the engulfment and cell motility (ELMO) family, which consists of six paralogs in mammals. Several members of the ELMO family have been shown to regulate a subset of GTPases within the Ras superfamily. However, ELMOD3 is a largely uncharacterized protein that has no previously known biochemical activities. We found that in rodents, within the sensory epithelia of the inner ear, ELMOD3 appears most pronounced in the stereocilia of cochlear hair cells. Fluorescently tagged ELMOD3 co-localized with the actin cytoskeleton in MDCK cells and actin-based microvilli of LLC-PK1-CL4 epithelial cells. The p.Leu265Ser mutation in the ELMO domain impaired each of these activities. Super-resolution imaging revealed instances of close association of ELMOD3 with actin at the plasma membrane of MDCK cells. Furthermore, recombinant human GST-ELMOD3 exhibited GTPase activating protein (GAP) activity against the Arl2 GTPase, which was completely abolished by the p.Leu265Ser mutation. Collectively, our data provide the first insights into the expression and biochemical properties of ELMOD3 and highlight its functional links to sound perception and actin cytoskeleton. Autosomal recessive nonsyndromic hearing loss is a genetically heterogeneous disorder. Here, we report a severe-to-profound mixed hearing loss locus, DFNB88 on chromosome 2p12-p11.2. Exome enrichment followed by massive parallel sequencing revealed a c.794T>C transition mutation in ELMOD3 that segregated with DFNB88-associated hearing loss in a large Pakistani family. This transition mutation is predicted to substitute a highly invariant leucine residue with serine (p.Leu265Ser) in the engulfment and cell motility (ELMO) domain of the protein. No biological activity has been described previously for the ELMOD3 protein. We investigated the biochemical properties and ELMOD3 expression to gain mechanistic insights into the function of ELMOD3 in the inner ear. In rodent inner ears, ELMOD3 immunoreactivity was observed in the cochlear and vestibular hair cells and supporting cells. However, ELMOD3 appears most pronounced in the stereocilia of cochlear hair cells. Ex vivo, ELMOD3 is associated with actin-based structures, and this link is impaired by the DFNB88 mutation. ELMOD3 exhibited GAP activity against Arl2, a small GTPase, providing a potential functional link between Arf family signaling and stereocilia actin-based cytoskeletal architecture. Our study provides new insights into the molecules that are necessary for the development and/or function of inner ear sensory cells.
Collapse
|
119
|
Biallelic nonsense mutations in the otogelin-like gene (OTOGL) in a child affected by mild to moderate hearing impairment. Gene 2013; 527:537-40. [DOI: 10.1016/j.gene.2013.06.044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/06/2013] [Accepted: 06/08/2013] [Indexed: 12/17/2022]
|
120
|
Higashi T, Lenz DR, Furuse M, Avraham KB. A "Tric" to tighten cell-cell junctions in the cochlea for hearing. J Clin Invest 2013; 123:3712-5. [PMID: 23979155 DOI: 10.1172/jci69651] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Tricellulin is a tricellular tight junction-associated membrane protein that controls movement of solutes at these specialized cell intersections. Mutations in the gene encoding tricellulin, TRIC, lead to nonsyndromic deafness. In this issue of the JCI, Nayak et al. created a gene-targeted knockin mouse in order to mimic the pathology of a human TRIC mutation. Deafness appears to be caused either by an increase in the K+ ion concentration around the basolateral surfaces of the outer hair cells or, alternatively, by an increase in small molecules such as ATP around the hair bundle, leading to cellular dysfunction and degeneration. Furthermore, the mice have features suggestive of syndromic hearing loss, which may have implications for care and treatment of patients harboring TRIC mutations.
Collapse
Affiliation(s)
- Tomohito Higashi
- Division of Cell Biology, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | | | | | | |
Collapse
|
121
|
Bao J, Bielski E, Bachhawat A, Taha D, Gunther LK, Thirumurugan K, Kitajiri SI, Sakamoto T. R1 motif is the major actin-binding domain of TRIOBP-4. Biochemistry 2013; 52:5256-64. [PMID: 23789641 DOI: 10.1021/bi400585h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
TRIOBP is an actin-bundling protein. Mutations of TRIOBP are associated with human deafness DFNB28. In vitro, TRIOBP isoform 4 (TRIOBP-4) forms dense F-actin bundles resembling the inner ear hair cell rootlet structure. Deletion of TRIOBP isoforms 4 and 5 leads to hearing loss in mice due to the absence of stereocilia rootlets. The mechanism of actin bundle formation by TRIOBP is not fully understood. The amino acid sequences of TRIOBP isoforms 4 and 5 contain two repeated motifs, referred to here as R1 and R2. To examine the potential role of R1 and R2 motifs in F-actin binding, we generated TRIOBP-4 mutant proteins deleted for R1 and/or R2, and then assessed their actin-binding activity and bundle formation in vitro using actin cosedimentation assays, and fluorescence and electron microscopy. Cellular distributions of the TRIOBP-4 mutants were examined by confocal microscopy. We showed that deletion of both R1 and R2 motifs completely disrupted the actin binding/bundling activities of TRIOBP-4 and impaired its localization to cellular actin cytoskeleton structures. By contrast, TRIOBP-4, lacking only R2 motif, retained its F-actin bundling ability and remained localized to actin filaments in cells, similar to full length TRIOBP-4. On the contrary, the R1 motif-deleted TRIOBP-4 mutant, which mainly consists of the R2 motif, formed thin F-actin bundles in vitro but failed to colocalize to actin filaments in cells. These results indicate that R1 motif is the major actin-binding domain of TRIOBP-4, and the binding of R2 motif with actin filaments is nonspecific.
Collapse
Affiliation(s)
- Jianjun Bao
- Department of Physics and Astronomy, Wayne State University , Detroit, Michigan 48201, United States
| | | | | | | | | | | | | | | |
Collapse
|
122
|
Kim KX, Fettiplace R. Developmental changes in the cochlear hair cell mechanotransducer channel and their regulation by transmembrane channel-like proteins. ACTA ACUST UNITED AC 2013; 141:141-8. [PMID: 23277480 PMCID: PMC3536526 DOI: 10.1085/jgp.201210913] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Vibration of the stereociliary bundles activates calcium-permeable mechanotransducer (MT) channels to initiate sound detection in cochlear hair cells. Different regions of the cochlea respond preferentially to different acoustic frequencies, with variation in the unitary conductance of the MT channels contributing to this tonotopic organization. Although the molecular identity of the MT channel remains uncertain, two members of the transmembrane channel–like family, Tmc1 and Tmc2, are crucial to hair cell mechanotransduction. We measured MT channel current amplitude and Ca2+ permeability along the cochlea’s longitudinal (tonotopic) axis during postnatal development of wild-type mice and mice lacking Tmc1 (Tmc1−/−) or Tmc2 (Tmc2−/−). In wild-type mice older than postnatal day (P) 4, MT current amplitude increased ∼1.5-fold from cochlear apex to base in outer hair cells (OHCs) but showed little change in inner hair cells (IHCs), a pattern apparent in mutant mice during the first postnatal week. After P7, the OHC MT current in Tmc1−/− (dn) mice declined to zero, consistent with their deafness phenotype. In wild-type mice before P6, the relative Ca2+ permeability, PCa, of the OHC MT channel decreased from cochlear apex to base. This gradient in PCa was not apparent in IHCs and disappeared after P7 in OHCs. In Tmc1−/− mice, PCa in basal OHCs was larger than that in wild-type mice (to equal that of apical OHCs), whereas in Tmc2−/−, PCa in apical and basal OHCs and IHCs was decreased compared with that in wild-type mice. We postulate that differences in Ca2+ permeability reflect different subunit compositions of the MT channel determined by expression of Tmc1 and Tmc2, with the latter conferring higher PCa in IHCs and immature apical OHCs. Changes in PCa with maturation are consistent with a developmental decrease in abundance of Tmc2 in OHCs but not in IHCs.
Collapse
Affiliation(s)
- Kyunghee X Kim
- Department of Neuroscience, University of Wisconsin-Madison, WI 53706, USA
| | | |
Collapse
|
123
|
Papal S, Cortese M, Legendre K, Sorusch N, Dragavon J, Sahly I, Shorte S, Wolfrum U, Petit C, El-Amraoui A. The giant spectrin βV couples the molecular motors to phototransduction and Usher syndrome type I proteins along their trafficking route. Hum Mol Genet 2013; 22:3773-88. [PMID: 23704327 DOI: 10.1093/hmg/ddt228] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutations in the myosin VIIa gene cause Usher syndrome type IB (USH1B), characterized by deaf-blindness. A delay of opsin trafficking has been observed in the retinal photoreceptor cells of myosin VIIa-deficient mice. We identified spectrin βV, the mammalian β-heavy spectrin, as a myosin VIIa- and rhodopsin-interacting partner in photoreceptor cells. Spectrin βV displays a polarized distribution from the Golgi apparatus to the base of the outer segment, which, unlike that of other β spectrins, matches the trafficking route of opsin and other phototransduction proteins. Formation of spectrin βV-rhodopsin complex could be detected in the differentiating photoreceptors as soon as their outer segment emerges. A failure of the spectrin βV-mediated coupling between myosin VIIa and opsin molecules thus probably accounts for the opsin transport delay in myosin VIIa-deficient mice. We showed that spectrin βV also associates with two USH1 proteins, sans (USH1G) and harmonin (USH1C). Spectrins are supposed to function as heteromers of α and β subunits, but fluorescence resonance energy transfer and in vitro binding experiments indicated that spectrin βV can also form homodimers, which likely supports its αII-independent βV functions. Finally, consistent with its distribution along the connecting cilia axonemes, spectrin βV binds to several subunits of the microtubule-based motor proteins, kinesin II and the dynein complex. We therefore suggest that spectrin βV homomers couple some USH1 proteins, opsin and other phototransduction proteins to both actin- and microtubule-based motors, thereby contributing to their transport towards the photoreceptor outer disks.
Collapse
Affiliation(s)
- Samantha Papal
- Institut Pasteur, Unité de génétique et physiologie de l'audition, Paris, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
124
|
|
125
|
Mizutari K, Fujioka M, Hosoya M, Bramhall N, Okano HJ, Okano H, Edge ASB. Notch inhibition induces cochlear hair cell regeneration and recovery of hearing after acoustic trauma. Neuron 2013; 77:58-69. [PMID: 23312516 DOI: 10.1016/j.neuron.2012.10.032] [Citation(s) in RCA: 293] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2012] [Indexed: 02/07/2023]
Abstract
Hearing loss due to damage to auditory hair cells is normally irreversible because mammalian hair cells do not regenerate. Here, we show that new hair cells can be induced and can cause partial recovery of hearing in ears damaged by noise trauma, when Notch signaling is inhibited by a γ-secretase inhibitor selected for potency in stimulating hair cell differentiation from inner ear stem cells in vitro. Hair cell generation resulted from an increase in the level of bHLH transcription factor Atoh1 in response to inhibition of Notch signaling. In vivo prospective labeling of Sox2-expressing cells with a Cre-lox system unambiguously demonstrated that hair cell generation resulted from transdifferentiation of supporting cells. Manipulating cell fate of cochlear sensory cells in vivo by pharmacological inhibition of Notch signaling is thus a potential therapeutic approach to the treatment of deafness.
Collapse
Affiliation(s)
- Kunio Mizutari
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02115, USA
| | | | | | | | | | | | | |
Collapse
|
126
|
Horn HF, Brownstein Z, Lenz DR, Shivatzki S, Dror AA, Dagan-Rosenfeld O, Friedman LM, Roux KJ, Kozlov S, Jeang KT, Frydman M, Burke B, Stewart CL, Avraham KB. The LINC complex is essential for hearing. J Clin Invest 2013; 123:740-50. [PMID: 23348741 DOI: 10.1172/jci66911] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 11/29/2012] [Indexed: 01/08/2023] Open
Abstract
Hereditary hearing loss is the most common sensory deficit. We determined that progressive high-frequency hearing loss in 2 families of Iraqi Jewish ancestry was due to homozygosity for the protein truncating mutation SYNE4 c.228delAT. SYNE4, a gene not previously associated with hearing loss, encodes nesprin-4 (NESP4), an outer nuclear membrane (ONM) protein expressed in the hair cells of the inner ear. The truncated NESP4 encoded by the families' mutation did not localize to the ONM. NESP4 and SUN domain-containing protein 1 (SUN1), which localizes to the inner nuclear membrane (INM), are part of the linker of nucleoskeleton and cytoskeleton (LINC) complex in the nuclear envelope. Mice lacking either Nesp4 or Sun1 were evaluated for hair cell defects and hearing loss. In both Nesp4-/- and Sun1-/- mice, OHCs formed normally, but degenerated as hearing matured, leading to progressive hearing loss. The nuclei of OHCs from mutant mice failed to maintain their basal localization, potentially affecting cell motility and hence the response to sound. These results demonstrate that the LINC complex is essential for viability and normal morphology of OHCs and suggest that the position of the nucleus in sensory epithelial cells is critical for maintenance of normal hearing.
Collapse
|
127
|
Cadherin defects in inherited human diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 116:361-84. [PMID: 23481203 DOI: 10.1016/b978-0-12-394311-8.00016-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The tight control of cell-cell connectivity mediated by cadherins is a key issue in human health and disease. The human genome contains over 115 genes encoding cadherins and cadherin-like proteins. Defects in about 21 of these proteins (8 classical, 5 desmosomal, 8 atypical cadherins) have been linked to inherited disorders in humans, including skin and hair disorders, cardiomyopathies, sensory defects associated with deafness and blindness, and psychiatric disorders. With the advent of exome and genome sequencing techniques, we can anticipate the discovery of yet more evidence for the involvement of additional cadherins. Elucidation of the related physiopathological mechanisms underlying these conditions should help to clarify the roles played by these cadherins in tissues and the ways in which defects in different cadherins cause such a wide spectrum of associated phenotypes. These disorders also constitute disparate model systems for investigations of the relative contributions of mechanical adhesive strength and intracellular signaling pathways to the pathogenic process for a given cadherin.
Collapse
|
128
|
Safieddine S, El-Amraoui A, Petit C. The auditory hair cell ribbon synapse: from assembly to function. Annu Rev Neurosci 2012; 35:509-28. [PMID: 22715884 DOI: 10.1146/annurev-neuro-061010-113705] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cochlear inner hair cells (IHCs), the mammalian auditory sensory cells, encode acoustic signals with high fidelity by Graded variations of their membrane potential trigger rapid and sustained vesicle exocytosis at their ribbon synapses. The kinetics of glutamate release allows proper transfer of sound information to the primary afferent auditory neurons. Understanding the physiological properties and underlying molecular mechanisms of the IHC synaptic machinery, and especially its high temporal acuity, which is pivotal to speech perception, is a central issue of auditory science. During the past decade, substantial progress in high-resolution imaging and electrophysiological recordings, as well as the development of genetic approaches both in humans and in mice, has produced major insights regarding the morphological, physiological, and molecular characteristics of this synapse. Here we review this recent knowledge and discuss how it enlightens the way the IHC ribbon synapse develops and functions.
Collapse
Affiliation(s)
- Saaid Safieddine
- Institut Pasteur, Unité de Génétique et Physiologie de l'Audition, F75015, Paris, France.
| | | | | |
Collapse
|
129
|
Sahly I, Dufour E, Schietroma C, Michel V, Bahloul A, Perfettini I, Pepermans E, Estivalet A, Carette D, Aghaie A, Ebermann I, Lelli A, Iribarne M, Hardelin JP, Weil D, Sahel JA, El-Amraoui A, Petit C. Localization of Usher 1 proteins to the photoreceptor calyceal processes, which are absent from mice. ACTA ACUST UNITED AC 2012; 199:381-99. [PMID: 23045546 PMCID: PMC3471240 DOI: 10.1083/jcb.201202012] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanisms underlying retinal dystrophy in Usher syndrome type I (USH1) remain unknown because mutant mice lacking any of the USH1 proteins-myosin VIIa, harmonin, cadherin-23, protocadherin-15, sans-do not display retinal degeneration. We found here that, in macaque photoreceptor cells, all USH1 proteins colocalized at membrane interfaces (i) between the inner and outer segments in rods and (ii) between the microvillus-like calyceal processes and the outer segment basolateral region in rods and cones. This pattern, conserved in humans and frogs, was mediated by the formation of an USH1 protein network, which was associated with the calyceal processes from the early embryonic stages of outer segment growth onwards. By contrast, mouse photoreceptors lacked calyceal processes and had no USH1 proteins at the inner-outer segment interface. We suggest that USH1 proteins form an adhesion belt around the basolateral region of the photoreceptor outer segment in humans, and that defects in this structure cause the retinal degeneration in USH1 patients.
Collapse
Affiliation(s)
- Iman Sahly
- Institut de la vision, Syndrome de Usher et autres Atteintes Rétino-Cochléaires, 75012 Paris, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
130
|
A mutation in the Srrm4 gene causes alternative splicing defects and deafness in the Bronx waltzer mouse. PLoS Genet 2012; 8:e1002966. [PMID: 23055939 PMCID: PMC3464207 DOI: 10.1371/journal.pgen.1002966] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Accepted: 08/08/2012] [Indexed: 11/19/2022] Open
Abstract
Sensory hair cells are essential for hearing and balance. Their development from epithelial precursors has been extensively characterized with respect to transcriptional regulation, but not in terms of posttranscriptional influences. Here we report on the identification and functional characterization of an alternative-splicing regulator whose inactivation is responsible for defective hair-cell development, deafness, and impaired balance in the spontaneous mutant Bronx waltzer (bv) mouse. We used positional cloning and transgenic rescue to locate the bv mutation to the splicing factor-encoding gene Ser/Arg repetitive matrix 4 (Srrm4). Transcriptome-wide analysis of pre–mRNA splicing in the sensory patches of embryonic inner ears revealed that specific alternative exons were skipped at abnormally high rates in the bv mice. Minigene experiments in a heterologous expression system confirmed that these skipped exons require Srrm4 for inclusion into the mature mRNA. Sequence analysis and mutagenesis experiments showed that the affected transcripts share a novel motif that is necessary for the Srrm4-dependent alternative splicing. Functional annotations and protein–protein interaction data indicated that the encoded proteins cluster in the secretion and neurotransmission pathways. In addition, the splicing of a few transcriptional regulators was found to be Srrm4 dependent, and several of the genes known to be targeted by these regulators were expressed at reduced levels in the bv mice. Although Srrm4 expression was detected in neural tissues as well as hair cells, analyses of the bv mouse cerebellum and neocortex failed to detect splicing defects. Our data suggest that Srrm4 function is critical in the hearing and balance organs, but not in all neural tissues. Srrm4 is the first alternative-splicing regulator to be associated with hearing, and the analysis of bv mice provides exon-level insights into hair-cell development. The identification of novel deafness-causing mutations has been instrumental in revealing unexpected mechanisms that are required for development of the sound- and gravity-sensing hair cells of the inner ear. The Bronx waltzer (bv) mouse is characterized by defects in hair-cell development, as well as by deafness and impaired balance. Here, we report on our identification of a mutation in the Ser/Arg repetitive matrix 4 (Srrm4) gene as the source of these defects. The encoded protein, Srrm4, belongs to a family of RNA splicing factors that regulate the inclusion of certain genetic information (i.e. alternative exons) into the transcribed RNA. We analyzed the molecular function of Srrm4 by comparing the exon composition of RNAs in the inner ear of bv and control mice. This approach revealed that, in the bv mice, specific alternative exons were omitted from protein-encoding RNAs. The affected transcripts shared two features: they contained a short sequence motif that was required for Srrm4-dependent splicing, and they encoded proteins that were related predominantly to secretion and neurotransmission. In addition, RNAs of a few gene expression regulators contained Srrm4-regulated exons. Our data suggest that Srrm4-dependent alternative splicing has a profound effect on the developmental program of hair cells.
Collapse
|
131
|
Mammano F. ATP-dependent intercellular Ca2+ signaling in the developing cochlea: facts, fantasies and perspectives. Semin Cell Dev Biol 2012; 24:31-9. [PMID: 23022499 DOI: 10.1016/j.semcdb.2012.09.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Accepted: 09/14/2012] [Indexed: 10/27/2022]
Abstract
Hearing relies on a sensitive mechanoelectrical transduction process in the cochlea of the inner ear. The cochlea contains sensory, secretory, neural, supporting and epithelial cells which are all essential to the sound transduction process. It is well known that a complex extracellular purinergic signaling system contributes to cochlear homeostasis, altering cochlear sensitivity and neural output via ATP-gated ion channels (P2X receptors) and G protein-coupled P2Y receptors. This review focuses on the emerging roles of ATP that are currently under investigation in the developing sensory epithelium, with particular emphasis on the link between ATP release, Ca(2+) signaling, the expression and function of gap junction proteins connexin26 and connexin30, and the acquisition of hearing.
Collapse
Affiliation(s)
- Fabio Mammano
- Dipartimento di Fisica e Astronomia G. Galilei, Università di Padova, 35131 Padova, Italy.
| |
Collapse
|
132
|
Wu L, Pan L, Zhang C, Zhang M. Large protein assemblies formed by multivalent interactions between cadherin23 and harmonin suggest a stable anchorage structure at the tip link of stereocilia. J Biol Chem 2012; 287:33460-71. [PMID: 22879593 PMCID: PMC3460447 DOI: 10.1074/jbc.m112.378505] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 08/03/2012] [Indexed: 11/06/2022] Open
Abstract
Stereocilia tip links of inner ear hair cells are subjected to constant stretching during hair-bundle deflection, and accordingly are well designed to prevent from being broken by mechanical tensions. The roots of tip links, which couple tip links with the cytoskeleton, supposedly play important roles in withstanding large forces under stimulated conditions. The upper root of the tip link is mainly formed by the cytoplasmic tail of cadherin23 and its actin-anchoring protein harmonin. However, the detailed organization mode of the two proteins that gives rise to a strong upper root remains unclear. Here we show that the exon68-encoded peptide of cadherin23 can either interact with the N-terminal domain (NTD) of harmonin or form a homodimer. We demonstrate that the three harmonin binding sites of cadherin23, namely the NTD-binding motif, the exon68 peptide, and the C-terminal PDZ binding motif, do not synergize with each other in binding to harmonin, instead they facilitate formation of polymeric cadherin23/harmonin complexes. The exon68 peptide can promote the cadherin23/harmonin polymer formation via either binding to harmonin NTD or self-dimerization. We propose that the polymeric cadherin23/harmonin complex formed beneath the upper tip link membranes may serve as part of the stable rootlet structure for anchoring the tip links of stereocilia.
Collapse
Affiliation(s)
- Lin Wu
- From the Division of Life Science, State Key Laboratory of Molecular Neuroscience
| | - Lifeng Pan
- From the Division of Life Science, State Key Laboratory of Molecular Neuroscience
| | - Chuchu Zhang
- From the Division of Life Science, State Key Laboratory of Molecular Neuroscience
| | - Mingjie Zhang
- From the Division of Life Science, State Key Laboratory of Molecular Neuroscience
- Center of Systems Biology and Human Health, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| |
Collapse
|
133
|
Xia L, Yin S, Wang J. Inner ear gene transfection in neonatal mice using adeno-associated viral vector: a comparison of two approaches. PLoS One 2012; 7:e43218. [PMID: 22912830 PMCID: PMC3422324 DOI: 10.1371/journal.pone.0043218] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 07/18/2012] [Indexed: 01/06/2023] Open
Abstract
Local gene transfection is a promising technique for the prevention and/or correction of inner ear diseases, particularly those resulting from genetic defects. Adeno-associated virus (AAV) is an ideal viral vector for inner ear gene transfection because of its safety, stability, long-lasting expression, and its high tropism for many different cell types. Recently, a new generation of AAV vectors with a tyrosine mutation (mut-AAV) has demonstrated significant improvement in transfection efficiency. A method for inner ear gene transfection via the intact round window membrane (RWM) has been developed in our laboratory. This method has not been tested in neonatal mice, an important species for the study of inherited hearing loss. Following a preliminary study to optimize the experimental protocol in order to reduce mortality, the present study investigated inner ear gene transfection in mice at postnatal day 7. We compared transfection efficiency, the safety of the scala tympani injection via RWM puncture, and the trans-RWM diffusion following partial digestion with an enzyme technique. The results revealed that approximately 47% of inner hair cells (IHCs) and 17% of outer hair cells (OHCs) were transfected via the trans-RWM approach. Transfection efficiency via RWM puncture (58% and 19% for IHCs and OHCs, respectively) was slightly higher, but the difference was not significant.
Collapse
Affiliation(s)
- Li Xia
- Department of Otolaryngology, Affiliated Sixth People's Hospital of Shanghai Jiao Tong University, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai, China
| | - Shankai Yin
- Department of Otolaryngology, Affiliated Sixth People's Hospital of Shanghai Jiao Tong University, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai, China
- * E-mail: (SY); (JW)
| | - Jian Wang
- Department of Otolaryngology, Affiliated Sixth People's Hospital of Shanghai Jiao Tong University, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai, China
- School of Human Communication Disorder, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail: (SY); (JW)
| |
Collapse
|
134
|
Peng H, Liu M, Pecka J, Beisel KW, Ding SJ. Proteomic analysis of the organ of corti using nanoscale liquid chromatography coupled with tandem mass spectrometry. Int J Mol Sci 2012; 13:8171-8188. [PMID: 22942697 PMCID: PMC3430228 DOI: 10.3390/ijms13078171] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Revised: 06/05/2012] [Accepted: 06/25/2012] [Indexed: 11/27/2022] Open
Abstract
The organ of Corti (OC) in the cochlea plays an essential role in auditory signal transduction in the inner ear. For its minute size and trace amount of proteins, the identification of the molecules in pathophysiologic processes in the bone-encapsulated OC requires both delicate separation and a highly sensitive analytical tool. Previously, we reported the development of a high resolution metal-free nanoscale liquid chromatography system for highly sensitive phosphoproteomic analysis. Here this system was coupled with a LTQ-Orbitrap XL mass spectrometer to investigate the OC proteome from normal hearing FVB/N male mice. A total of 628 proteins were identified from six replicates of single LC-MS/MS analysis, with a false discovery rate of 1% using the decoy database approach by the OMSSA search engine. This is currently the largest proteome dataset for the OC. A total of 11 proteins, including cochlin, myosin VI, and myosin IX, were identified that when defective are associated with hearing impairment or loss. This study demonstrated the effectiveness of our nanoLC-MS/MS platform for sensitive identification of hearing loss-associated proteins from minute amount of tissue samples.
Collapse
Affiliation(s)
- Hong Peng
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA; E-Mails: (H.P.); (M.L.)
- Department of Environmental, Agricultural & Occupational Health, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Miao Liu
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA; E-Mails: (H.P.); (M.L.)
| | - Jason Pecka
- Department of Biomedical Sciences, Creighton University, Omaha, NE 68178, USA; E-Mail:
| | - Kirk W. Beisel
- Department of Biomedical Sciences, Creighton University, Omaha, NE 68178, USA; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (K.W.B.); (S.-J.D.); Tel.: +1-402-280-4069 (K.W.B.); +1-402-559-4183 (S.-J.D.); Fax: +1-402-280-2690 (K.W.B.); +1-402-559-4651 (S.-J.D.)
| | - Shi-Jian Ding
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA; E-Mails: (H.P.); (M.L.)
- Mass Spectrometry and Proteomics Core Facility, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Authors to whom correspondence should be addressed; E-Mails: (K.W.B.); (S.-J.D.); Tel.: +1-402-280-4069 (K.W.B.); +1-402-559-4183 (S.-J.D.); Fax: +1-402-280-2690 (K.W.B.); +1-402-559-4651 (S.-J.D.)
| |
Collapse
|
135
|
Delmaghani S, Aghaie A, Michalski N, Bonnet C, Weil D, Petit C. Defect in the gene encoding the EAR/EPTP domain-containing protein TSPEAR causes DFNB98 profound deafness. Hum Mol Genet 2012; 21:3835-44. [PMID: 22678063 DOI: 10.1093/hmg/dds212] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We report a consanguineous Iranian family affected by congenital profound sensorineural deafness segregating in an autosomal recessive mode. Auditory tests implicated at least a cochlear defect in these patients. We mapped the deafness, autosomal recessive (DFNB) locus involved by linkage analysis to a 4.8 Mb region at chromosome 21q22.3-qter. Exclusion of the DFNB8/10 gene TMPRSS3, located in this chromosomal interval, led us to identify a new deafness locus, DFNB98. Whole exome sequencing allowed us to identify a homozygous frame-shifting mutation (c.1726G>T+c.1728delC) in the gene TSPEAR (thrombospondin-type laminin G domain and EAR repeats). This truncating mutation (p.V576LfsX37) impeded the secretion of the encoded protein by cells transfected with the mutated gene. Alternative splicing of TSPEAR transcripts predict two protein isoforms, 522 and 669 amino acids in length, both of which would be affected by the mutation. These isoforms are composed of a thrombospondin-type laminin G (TSP) domain followed by seven tandemly organized epilepsy-associated repeats (EARs), probably forming a β-propeller domain. Tspear is expressed in a variety of murine tissues. Only the larger Tspear transcript was found in the cochlea, and the protein was detected by immunofluorescence at the surface of the hair bundles of sensory cells. The mammalian EAR protein family includes six known members. Defects in four of them, i.e. Lgi1, Lgi2, Vlgr1 and, we show here, TSPEAR, cause disorders with auditory features: epilepsy, which can include auditory features in humans; audiogenic seizures in animals; and/or hearing impairments in humans and mice. These observations demonstrate that EAR-containing proteins are essential for the development and function of the auditory system.
Collapse
Affiliation(s)
- Sedigheh Delmaghani
- Institut Pasteur, Unité de Génétique et Physiologie de l’Audition, Paris, France
| | | | | | | | | | | |
Collapse
|
136
|
Zheng QY, Scarborough JD, Zheng Y, Yu H, Choi D, Gillespie PG. Digenic inheritance of deafness caused by 8J allele of myosin-VIIA and mutations in other Usher I genes. Hum Mol Genet 2012; 21:2588-98. [PMID: 22381527 PMCID: PMC3349429 DOI: 10.1093/hmg/dds084] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 01/18/2012] [Accepted: 02/24/2012] [Indexed: 01/01/2023] Open
Abstract
Inherited hearing loss in mice has contributed substantially to our understanding of inner-ear function. We identified a new allele at the Myo7a locus, Myo7a(sh1-8J); genomic characterization indicated that Myo7a(sh1-8J) arose from complex deletion encompassing exons 38-40 and 42-46. Homozygous mutant mice had no detectable auditory brainstem response, displayed highly disorganized hair-cell stereocilia and had no detectable MYO7A protein. We generated mice that were digenic heterozygotes for Myo7a(sh1-8J) and one of each Cdh23(v-2J), Ush1g(js) or Pcdh15(av-3J) alleles, or an Ush1c null allele. Significant levels of age-related hearing loss were detected in +/Myo7a(sh1-8J) +/Ush1g(js), +/Myo7a(sh1-8J) +/Cdh23(v-2J) and +/Myo7a(sh1-8J) +/Pcdh15(av-3J) double heterozygous mice compared with age-matched single heterozygous animals, suggesting epistasis between Myo7a and each of the three loci. +/Pcdh15(av-3J) +/Ush1g(js) double heterozygous mice also showed elevated hearing loss, suggesting Pcdh15-Ush1g epistasis. While we readily detected MYO7A, USH1C, CDH23 and PCDH15 using mass spectrometry of purified chick utricle hair bundles, we did not detect USH1G. Consistent with that observation, Ush1g microarray signals were much lower in chick cochlea than those of Myo7a, Ush1c, Cdh23 and Pcdh15 and were not detected in the chick utricle. These experiments confirm the importance of MYO7A for the development and maintenance of bundle function and support the suggestion that MYO7A, USH1G (Sans) and CDH23 form the upper tip-link complex in adult mice, likely in combination with USH1C (harmonin). MYO7A, USH1G and PCDH15 may form another complex in stereocilia. USH1G may be a limiting factor in both complexes.
Collapse
Affiliation(s)
- Qing Yin Zheng
- Otolaryngology-Head and Neck Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA
| | | | - Ye Zheng
- Otolaryngology-Head and Neck Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Heping Yu
- Otolaryngology-Head and Neck Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA
| | - Dongseok Choi
- Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, OR 97239, USA
| | | |
Collapse
|
137
|
Brownstein Z, Bhonker Y, Avraham KB. High-throughput sequencing to decipher the genetic heterogeneity of deafness. Genome Biol 2012; 13:245. [PMID: 22647651 PMCID: PMC3446284 DOI: 10.1186/gb-2012-13-5-245] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Identifying genes causing non-syndromic hearing loss has been challenging using traditional approaches. We describe the impact that high-throughput sequencing approaches are having in discovery of genes related to hearing loss and the implications for clinical diagnosis.
Collapse
Affiliation(s)
- Zippora Brownstein
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | | | | |
Collapse
|
138
|
Pan L, Zhang M. Structures of usher syndrome 1 proteins and their complexes. Physiology (Bethesda) 2012; 27:25-42. [PMID: 22311968 DOI: 10.1152/physiol.00037.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Usher syndrome 1 (USH1) is the most common and severe form of hereditary loss of hearing and vision. Genetic, physiological, and cell biological studies, together with recent structural investigations, have not only uncovered the physiological functions of the five USH1 proteins but also provided mechanistic explanations for the hearing and visual deficiencies in humans caused by USH1 mutations. This review focuses on the structural basis of the USH1 protein complex organization.
Collapse
Affiliation(s)
- Lifeng Pan
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | | |
Collapse
|
139
|
Frenzel H, Bohlender J, Pinsker K, Wohlleben B, Tank J, Lechner SG, Schiska D, Jaijo T, Rüschendorf F, Saar K, Jordan J, Millán JM, Gross M, Lewin GR. A genetic basis for mechanosensory traits in humans. PLoS Biol 2012; 10:e1001318. [PMID: 22563300 PMCID: PMC3341339 DOI: 10.1371/journal.pbio.1001318] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 03/20/2012] [Indexed: 11/18/2022] Open
Abstract
Hearing and touch are genetically related, and people with excellent hearing are more likely to have a fine sense of touch and vice versa. In all vertebrates hearing and touch represent two distinct sensory systems that both rely on the transformation of mechanical force into electrical signals. There is an extensive literature describing single gene mutations in humans that cause hearing impairment, but there are essentially none for touch. Here we first asked if touch sensitivity is a heritable trait and second whether there are common genes that influence different mechanosensory senses like hearing and touch in humans. Using a classical twin study design we demonstrate that touch sensitivity and touch acuity are highly heritable traits. Quantitative phenotypic measures of different mechanosensory systems revealed significant correlations between touch and hearing acuity in a healthy human population. Thus mutations in genes causing deafness genes could conceivably negatively influence touch sensitivity. In agreement with this hypothesis we found that a proportion of a cohort of congenitally deaf young adults display significantly impaired measures of touch sensitivity compared to controls. In contrast, blind individuals showed enhanced, not diminished touch acuity. Finally, by examining a cohort of patients with Usher syndrome, a genetically well-characterized deaf-blindness syndrome, we could show that recessive pathogenic mutations in the USH2A gene influence touch acuity. Control Usher syndrome cohorts lacking demonstrable pathogenic USH2A mutations showed no impairment in touch acuity. Our study thus provides comprehensive evidence that there are common genetic elements that contribute to touch and hearing and has identified one of these genes as USH2A. In humans many genes have been identified that cause deafness when mutated, but no equivalent genes have been identified that are required for touch. Here, we asked whether genes that influence hearing can also influence touch. Using identical and non-identical human twins it was possible to show that touch performance is substantially influenced by genes. Furthermore, people who have excellent hearing are more likely to have a fine sense of touch and vice versa. Interestingly, people who suffer from congenital deafness have a higher chance of having poor touch performance. In a genetically defined form of human deafness, Usher syndrome type II, a single mutated gene was identified that also impairs touch. Touch and hearing are thus intricately intertwined and there may be other touch/hearing genes waiting to be discovered.
Collapse
Affiliation(s)
- Henning Frenzel
- Department of Neuroscience, Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany
| | - Jörg Bohlender
- Department of Audiology and Phoniatrics, Charité Universitätsmedizin, Berlin, Germany
| | - Katrin Pinsker
- Department of Audiology and Phoniatrics, Charité Universitätsmedizin, Berlin, Germany
| | - Bärbel Wohlleben
- Department of Audiology and Phoniatrics, Charité Universitätsmedizin, Berlin, Germany
| | - Jens Tank
- Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany
| | - Stefan G. Lechner
- Department of Neuroscience, Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany
| | - Daniela Schiska
- Department of Audiology and Phoniatrics, Charité Universitätsmedizin, Berlin, Germany
| | - Teresa Jaijo
- Genetics Unit, Hospital Universitario La Fe, and CIBERER, Valencia, Spain
| | - Franz Rüschendorf
- Experimental Genetics of Cardiovascular Disease, Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany
| | - Kathrin Saar
- Experimental Genetics of Cardiovascular Disease, Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany
| | - Jens Jordan
- Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany
| | - José M. Millán
- Genetics Unit, Hospital Universitario La Fe, and CIBERER, Valencia, Spain
| | - Manfred Gross
- Department of Audiology and Phoniatrics, Charité Universitätsmedizin, Berlin, Germany
| | - Gary R. Lewin
- Department of Neuroscience, Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany
- * E-mail:
| |
Collapse
|
140
|
Luo N, West CC, Murga-Zamalloa CA, Sun L, Anderson RM, Wells CD, Weinreb RN, Travers JB, Khanna H, Sun Y. OCRL localizes to the primary cilium: a new role for cilia in Lowe syndrome. Hum Mol Genet 2012; 21:3333-44. [PMID: 22543976 PMCID: PMC3392109 DOI: 10.1093/hmg/dds163] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Oculocerebral renal syndrome of Lowe (OCRL or Lowe syndrome), a severe X-linked congenital disorder characterized by congenital cataracts and glaucoma, mental retardation and kidney dysfunction, is caused by mutations in the OCRL gene. OCRL is a phosphoinositide 5-phosphatase that interacts with small GTPases and is involved in intracellular trafficking. Despite extensive studies, it is unclear how OCRL mutations result in a myriad of phenotypes found in Lowe syndrome. Our results show that OCRL localizes to the primary cilium of retinal pigment epithelial cells, fibroblasts and kidney tubular cells. Lowe syndrome-associated mutations in OCRL result in shortened cilia and this phenotype can be rescued by the introduction of wild-type OCRL; in vivo, knockdown of ocrl in zebrafish embryos results in defective cilia formation in Kupffer vesicles and cilia-dependent phenotypes. Cumulatively, our data provide evidence for a role of OCRL in cilia maintenance and suggest the involvement of ciliary dysfunction in the manifestation of Lowe syndrome.
Collapse
Affiliation(s)
- Na Luo
- Department of Ophthalmology, Glick Eye Institute, Indiana University, 1601 W Michigan St., Indianapolis, IN 46202, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
141
|
The dynamic architecture of photoreceptor ribbon synapses: cytoskeletal, extracellular matrix, and intramembrane proteins. Vis Neurosci 2012; 28:453-71. [PMID: 22192503 DOI: 10.1017/s0952523811000356] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Rod and cone photoreceptors possess ribbon synapses that assist in the transmission of graded light responses to second-order bipolar and horizontal cells of the vertebrate retina. Proper functioning of the synapse requires the juxtaposition of presynaptic release sites immediately adjacent to postsynaptic receptors. In this review, we focus on the synaptic, cytoskeletal, and extracellular matrix proteins that help to organize photoreceptor ribbon synapses in the outer plexiform layer. We examine the proteins that foster the clustering of release proteins, calcium channels, and synaptic vesicles in the presynaptic terminals of photoreceptors adjacent to their postsynaptic contacts. Although many proteins interact with one another in the presynaptic terminal and synaptic cleft, these protein-protein interactions do not create a static and immutable structure. Instead, photoreceptor ribbon synapses are remarkably dynamic, exhibiting structural changes on both rapid and slow time scales.
Collapse
|
142
|
Chanut-Delalande H, Ferrer P, Payre F, Plaza S. Effectors of tridimensional cell morphogenesis and their evolution. Semin Cell Dev Biol 2012; 23:341-9. [PMID: 22406682 DOI: 10.1016/j.semcdb.2012.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Revised: 02/10/2012] [Accepted: 03/01/2012] [Indexed: 01/07/2023]
Abstract
One of the most challenging problems in biology resides in unraveling the molecular mechanisms, hardwired in the genome, that define and regulate the multiscale tridimensional organization of organs, tissues and individual cells. While works in cultured cells have revealed the importance of cytoskeletal networks for cell architecture, in vivo models are now required to explore how such a variety in cell shape is produced during development, in interaction with neighboring cells and tissues. The genetic analysis of epidermis development in Drosophila has provided an unbiased way to identify mechanisms remodeling the shape of epidermal cells, to form apical trichomes during terminal differentiation. Since hearing in vertebrates relies on apical cell extensions in sensory cells of the cochlea, called stereocilia, the mapping of human genes causing hereditary deafness has independently identified several factors required for this peculiar tridimensional organization. In this review, we summarized recent results obtained toward the identification of genes involved in these localized changes in cell shape and discuss their evolution throughout developmental processes and species.
Collapse
|
143
|
|
144
|
Kazmierczak P, Müller U. Sensing sound: molecules that orchestrate mechanotransduction by hair cells. Trends Neurosci 2011; 35:220-9. [PMID: 22177415 DOI: 10.1016/j.tins.2011.10.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 10/25/2011] [Accepted: 10/27/2011] [Indexed: 01/19/2023]
Abstract
Animals use acoustic signals to communicate and to obtain information about their environment. The processing of acoustic signals is initiated at auditory sense organs, where mechanosensory hair cells convert sound-induced vibrations into electrical signals. Although the biophysical principles underlying the mechanotransduction process in hair cells have been characterized in much detail over the past 30 years, the molecular building-blocks of the mechanotransduction machinery have proved to be difficult to determine. We review here recent studies that have both identified some of these molecules and established the mechanisms by which they regulate the activity of the still-elusive mechanotransduction channel.
Collapse
Affiliation(s)
- Piotr Kazmierczak
- Dorris Neuroscience Center, Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | | |
Collapse
|
145
|
Abstract
Hereditary deafness is genetically heterogeneous such that mutations of many different genes can cause hearing loss. This review focuses on the evidence and implications that several of these deafness genes encode actin-interacting proteins or actin itself. There is a growing appreciation of the contribution of the actin interactome in stereocilia development, maintenance, mechanotransduction and malfunction of the auditory system.
Collapse
|
146
|
Le Quesne Stabej P, Saihan Z, Rangesh N, Steele-Stallard HB, Ambrose J, Coffey A, Emmerson J, Haralambous E, Hughes Y, Steel KP, Luxon LM, Webster AR, Bitner-Glindzicz M. Comprehensive sequence analysis of nine Usher syndrome genes in the UK National Collaborative Usher Study. J Med Genet 2011; 49:27-36. [PMID: 22135276 PMCID: PMC3678402 DOI: 10.1136/jmedgenet-2011-100468] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Background Usher syndrome (USH) is an autosomal recessive disorder comprising retinitis pigmentosa, hearing loss and, in some cases, vestibular dysfunction. It is clinically and genetically heterogeneous with three distinctive clinical types (I–III) and nine Usher genes identified. This study is a comprehensive clinical and genetic analysis of 172 Usher patients and evaluates the contribution of digenic inheritance. Methods The genes MYO7A, USH1C, CDH23, PCDH15, USH1G, USH2A, GPR98, WHRN, CLRN1 and the candidate gene SLC4A7 were sequenced in 172 UK Usher patients, regardless of clinical type. Results No subject had definite mutations (nonsense, frameshift or consensus splice site mutations) in two different USH genes. Novel missense variants were classified UV1-4 (unclassified variant): UV4 is ‘probably pathogenic’, based on control frequency <0.23%, identification in trans to a pathogenic/probably pathogenic mutation and segregation with USH in only one family; and UV3 (‘likely pathogenic’) as above, but no information on phase. Overall 79% of identified pathogenic/UV4/UV3 variants were truncating and 21% were missense changes. MYO7A accounted for 53.2%, and USH1C for 14.9% of USH1 families (USH1C:c.496+1G>A being the most common USH1 mutation in the cohort). USH2A was responsible for 79.3% of USH2 families and GPR98 for only 6.6%. No mutations were found in USH1G, WHRN or SLC4A7. Conclusions One or two pathogenic/likely pathogenic variants were identified in 86% of cases. No convincing cases of digenic inheritance were found. It is concluded that digenic inheritance does not make a significant contribution to Usher syndrome; the observation of multiple variants in different genes is likely to reflect polymorphic variation, rather than digenic effects.
Collapse
|
147
|
Choi BY, Kim HM, Ito T, Lee KY, Li X, Monahan K, Wen Y, Wilson E, Kurima K, Saunders TL, Petralia RS, Wangemann P, Friedman TB, Griffith AJ. Mouse model of enlarged vestibular aqueducts defines temporal requirement of Slc26a4 expression for hearing acquisition. J Clin Invest 2011; 121:4516-25. [PMID: 21965328 DOI: 10.1172/jci59353] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 08/10/2011] [Indexed: 12/13/2022] Open
Abstract
Mutations in human SLC26A4 are a common cause of hearing loss associated with enlarged vestibular aqueducts (EVA). SLC26A4 encodes pendrin, an anion-base exchanger expressed in inner ear epithelial cells that secretes HCO3- into endolymph. Studies of Slc26a4-null mice indicate that pendrin is essential for inner ear development, but have not revealed whether pendrin is specifically necessary for homeostasis. Slc26a4-null mice are profoundly deaf, with severe inner ear malformations and degenerative changes that do not model the less severe human phenotype. Here, we describe studies in which we generated a binary transgenic mouse line in which Slc26a4 expression could be induced with doxycycline. The transgenes were crossed onto the Slc26a4-null background so that all functional pendrin was derived from the transgenes. Varying the temporal expression of Slc26a4 revealed that E16.5 to P2 was the critical interval in which pendrin was required for acquisition of normal hearing. Lack of pendrin during this period led to endolymphatic acidification, loss of the endocochlear potential, and failure to acquire normal hearing. Doxycycline initiation at E18.5 or discontinuation at E17.5 resulted in partial hearing loss approximating the human EVA auditory phenotype. These data collectively provide mechanistic insight into hearing loss caused by SLC26A4 mutations and establish a model for further studies of EVA-associated hearing loss.
Collapse
Affiliation(s)
- Byung Yoon Choi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Rockville, Maryland, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
148
|
Lenz DR, Avraham KB. Hereditary hearing loss: from human mutation to mechanism. Hear Res 2011; 281:3-10. [PMID: 21664957 DOI: 10.1016/j.heares.2011.05.021] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 05/26/2011] [Accepted: 05/27/2011] [Indexed: 11/17/2022]
Abstract
The genetic heterogeneity of hereditary hearing loss is thus far represented by hundreds of genes encoding a large variety of proteins. Mutations in these genes have been discovered for patients with different modes of inheritance and types of hearing loss, ranging from syndromic to non-syndromic and mild to profound. In many cases, the mechanisms whereby the mutations lead to hearing loss have been partly elucidated using cell culture systems and mouse and other animal models. The discovery of the genes has completely changed the practice of genetic counseling in this area, providing potential diagnosis in many cases that can be coupled with clinical phenotypes and offer predictive information for families. In this review we provide three examples of gene discovery in families with hereditary hearing loss, all associated with elucidation of some of the mechanisms leading to hair cell degeneration and pathology of deafness.
Collapse
Affiliation(s)
- Danielle R Lenz
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | |
Collapse
|
149
|
Hashimoto Y, Kim DJ, Adams JC. The roles of fascins in health and disease. J Pathol 2011; 224:289-300. [DOI: 10.1002/path.2894] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 03/02/2011] [Accepted: 03/04/2011] [Indexed: 02/06/2023]
|
150
|
Schraders M, Haas SA, Weegerink NJD, Oostrik J, Hu H, Hoefsloot LH, Kannan S, Huygen PLM, Pennings RJE, Admiraal RJC, Kalscheuer VM, Kunst HPM, Kremer H. Next-generation sequencing identifies mutations of SMPX, which encodes the small muscle protein, X-linked, as a cause of progressive hearing impairment. Am J Hum Genet 2011; 88:628-34. [PMID: 21549342 DOI: 10.1016/j.ajhg.2011.04.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Revised: 04/07/2011] [Accepted: 04/18/2011] [Indexed: 01/12/2023] Open
Abstract
In a Dutch family with an X-linked postlingual progressive hearing impairment, a critical linkage interval was determined to span a region of 12.9 Mb flanked by the markers DXS7108 and DXS7110. This interval overlaps with the previously described DFNX4 locus and contains 75 annotated genes. Subsequent next-generation sequencing (NGS) detected one variant within the linkage interval, a nonsense mutation in SMPX. SMPX encodes the small muscle protein, X-linked (SMPX). Further screening was performed on 26 index patients from small families for which X-linked inheritance of nonsyndromic hearing impairment (NSHI) was not excluded. We detected a frameshift mutation in SMPX in one of the patients. Segregation analysis of both mutations in the families in whom they were found revealed that the mutations cosegregated with hearing impairment. Although we show that SMPX is expressed in many different organs, including the human inner ear, no obvious symptoms other than hearing impairment were observed in the patients. SMPX had previously been demonstrated to be specifically expressed in striated muscle and, therefore, seemed an unlikely candidate gene for hearing impairment. We hypothesize that SMPX functions in inner ear development and/or maintenance in the IGF-1 pathway, the integrin pathway through Rac1, or both.
Collapse
Affiliation(s)
- Margit Schraders
- Department of Otorhinolaryngology, Head and Neck Surgery, Nijmegen, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|