1
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Gilbert BL, Zhu S, Salameh A, Sun S, Alagramam KN, McDermott BM. Actin Crosslinking Family Protein 7 Deficiency Does Not Impair Hearing in Young Mice. Front Cell Dev Biol 2021; 9:709442. [PMID: 34917607 PMCID: PMC8670236 DOI: 10.3389/fcell.2021.709442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 09/01/2021] [Indexed: 11/13/2022] Open
Abstract
To enable hearing, the sensory hair cell contains specialized subcellular structures at its apical region, including the actin-rich cuticular plate and circumferential band. ACF7 (actin crosslinking family protein 7), encoded by the gene Macf1 (microtubule and actin crosslinking factor 1), is a large cytoskeletal crosslinking protein that interacts with microtubules and filamentous actin to shape cells. ACF7 localizes to the cuticular plate and the circumferential band in the hair cells of vertebrates. The compelling expression pattern of ACF7 in hair cells, combined with conserved roles of this protein in the cytoskeleton of various cell types in invertebrates and vertebrates, led to the hypothesis that ACF7 performs a key function in the subcellular architecture of hair cells. To test the hypothesis, we conditionally target Macf1 in the inner ears of mice. Surprisingly, our data show that in young, but mature, conditional knockout mice cochlear hair cell survival, planar cell polarity, organization of the hair cells within the organ of Corti, and capacity to hear are not significantly impacted. Overall, these results fail to support the hypothesis that ACF7 is an essential hair cell protein in young mice, and the purpose of ACF7 expression in the hair cell remains to be understood.
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Affiliation(s)
- Benjamin L Gilbert
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Department of Biology, Case Western Reserve University, Cleveland, OH, United States
| | - Shaoyuan Zhu
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Department of Biology, Case Western Reserve University, Cleveland, OH, United States
| | - Ahlam Salameh
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Shenyu Sun
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Department of Biology, Case Western Reserve University, Cleveland, OH, United States
| | - Kumar N Alagramam
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Brian M McDermott
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Department of Biology, Case Western Reserve University, Cleveland, OH, United States.,Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, United States
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2
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Vona B, Mazaheri N, Lin SJ, Dunbar LA, Maroofian R, Azaiez H, Booth KT, Vitry S, Rad A, Rüschendorf F, Varshney P, Fowler B, Beetz C, Alagramam KN, Murphy D, Shariati G, Sedaghat A, Houlden H, Petree C, VijayKumar S, Smith RJH, Haaf T, El-Amraoui A, Bowl MR, Varshney GK, Galehdari H. A biallelic variant in CLRN2 causes non-syndromic hearing loss in humans. Hum Genet 2021; 140:915-931. [PMID: 33496845 PMCID: PMC8099798 DOI: 10.1007/s00439-020-02254-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/31/2020] [Indexed: 01/10/2023]
Abstract
Deafness, the most frequent sensory deficit in humans, is extremely heterogeneous with hundreds of genes involved. Clinical and genetic analyses of an extended consanguineous family with pre-lingual, moderate-to-profound autosomal recessive sensorineural hearing loss, allowed us to identify CLRN2, encoding a tetraspan protein, as a new deafness gene. Homozygosity mapping followed by exome sequencing identified a 14.96 Mb locus on chromosome 4p15.32p15.1 containing a likely pathogenic missense variant in CLRN2 (c.494C > A, NM_001079827.2) segregating with the disease. Using in vitro RNA splicing analysis, we show that the CLRN2 c.494C > A variant leads to two events: (1) the substitution of a highly conserved threonine (uncharged amino acid) to lysine (charged amino acid) at position 165, p.(Thr165Lys), and (2) aberrant splicing, with the retention of intron 2 resulting in a stop codon after 26 additional amino acids, p.(Gly146Lysfs*26). Expression studies and phenotyping of newly produced zebrafish and mouse models deficient for clarin 2 further confirm that clarin 2, expressed in the inner ear hair cells, is essential for normal organization and maintenance of the auditory hair bundles, and for hearing function. Together, our findings identify CLRN2 as a new deafness gene, which will impact future diagnosis and treatment for deaf patients.
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Affiliation(s)
- Barbara Vona
- Institute of Human Genetics, Julius Maximilians University Würzburg, Würzburg, Germany. .,Department of Otolaryngology-Head and Neck Surgery, Tübingen Hearing Research Centre, Eberhard Karls University Tübingen, Tübingen, Germany.
| | - Neda Mazaheri
- Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Sheng-Jia Lin
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Lucy A Dunbar
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Campus, Didcot, OX11 0RD, UK
| | - Reza Maroofian
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Hela Azaiez
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology and Interdisciplinary Graduate Program in Molecular Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Kevin T Booth
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology and Interdisciplinary Graduate Program in Molecular Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.,Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Sandrine Vitry
- Unit Progressive Sensory Disorders, Pathophysiology and Therapy Institut Pasteur, Institut de L'Audition, INSERM-UMRS1120, Sorbonne Université, 63 rue de Charenton, 75012, Paris, France
| | - Aboulfazl Rad
- Department of Otolaryngology-Head and Neck Surgery, Tübingen Hearing Research Centre, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Franz Rüschendorf
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125, Berlin, Germany
| | - Pratishtha Varshney
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Ben Fowler
- Imaging & Histology Core, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | | | - Kumar N Alagramam
- Department of Otolaryngology, School of Medicine, University Hospitals Cleveland Medical Center, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH, 44106, USA.,Department of Neurosciences, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH, 44106, USA.,Department of Genetics and Genomic Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - David Murphy
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Gholamreza Shariati
- Department of Medical Genetics, Faculty of Medicine, Ahvaz Jundishapur, University of Medical Sciences, Ahvaz, Iran.,Narges Medical Genetics and Prenatal Diagnostics Laboratory, East Mihan Ave, Kianpars, Ahvaz, Iran
| | - Alireza Sedaghat
- Diabetes Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Cassidy Petree
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Shruthi VijayKumar
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Richard J H Smith
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology and Interdisciplinary Graduate Program in Molecular Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Thomas Haaf
- Institute of Human Genetics, Julius Maximilians University Würzburg, Würzburg, Germany
| | - Aziz El-Amraoui
- Unit Progressive Sensory Disorders, Pathophysiology and Therapy Institut Pasteur, Institut de L'Audition, INSERM-UMRS1120, Sorbonne Université, 63 rue de Charenton, 75012, Paris, France
| | - Michael R Bowl
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Campus, Didcot, OX11 0RD, UK. .,UCL Ear Institute, University College London, 332 Gray's Inn Road, London, WC1X 8EE, UK.
| | - Gaurav K Varshney
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Hamid Galehdari
- Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
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3
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Dunbar LA, Patni P, Aguilar C, Mburu P, Corns L, Wells HRR, Delmaghani S, Parker A, Johnson S, Williams D, Esapa CT, Simon MM, Chessum L, Newton S, Dorning J, Jeyarajan P, Morse S, Lelli A, Codner GF, Peineau T, Gopal SR, Alagramam KN, Hertzano R, Dulon D, Wells S, Williams FM, Petit C, Dawson SJ, Brown SDM, Marcotti W, El‐Amraoui A, Bowl MR. Clarin-2 is essential for hearing by maintaining stereocilia integrity and function. EMBO Mol Med 2019; 11:e10288. [PMID: 31448880 PMCID: PMC6728604 DOI: 10.15252/emmm.201910288] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 11/21/2022] Open
Abstract
Hearing relies on mechanically gated ion channels present in the actin-rich stereocilia bundles at the apical surface of cochlear hair cells. Our knowledge of the mechanisms underlying the formation and maintenance of the sound-receptive structure is limited. Utilizing a large-scale forward genetic screen in mice, genome mapping and gene complementation tests, we identified Clrn2 as a new deafness gene. The Clrn2clarinet/clarinet mice (p.Trp4* mutation) exhibit a progressive, early-onset hearing loss, with no overt retinal deficits. Utilizing data from the UK Biobank study, we could show that CLRN2 is involved in human non-syndromic progressive hearing loss. Our in-depth morphological, molecular and functional investigations establish that while it is not required for initial formation of cochlear sensory hair cell stereocilia bundles, clarin-2 is critical for maintaining normal bundle integrity and functioning. In the differentiating hair bundles, lack of clarin-2 leads to loss of mechano-electrical transduction, followed by selective progressive loss of the transducing stereocilia. Together, our findings demonstrate a key role for clarin-2 in mammalian hearing, providing insights into the interplay between mechano-electrical transduction and stereocilia maintenance.
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Affiliation(s)
- Lucy A Dunbar
- Mammalian Genetics UnitMRC Harwell InstituteHarwellUK
| | - Pranav Patni
- Déficits Sensoriels ProgressifsInstitut PasteurINSERM UMR‐S 1120Sorbonne UniversitésParisFrance
| | | | | | - Laura Corns
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Helena RR Wells
- Department of Twin Research & Genetic EpidemiologyKing's College LondonLondonUK
| | - Sedigheh Delmaghani
- Déficits Sensoriels ProgressifsInstitut PasteurINSERM UMR‐S 1120Sorbonne UniversitésParisFrance
| | - Andrew Parker
- Mammalian Genetics UnitMRC Harwell InstituteHarwellUK
| | - Stuart Johnson
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | | | | | | | | | | | | | | | - Susan Morse
- Mammalian Genetics UnitMRC Harwell InstituteHarwellUK
| | - Andrea Lelli
- Génétique et Physiologie de l'AuditionInstitut PasteurINSERM UMR‐S 1120Collège de FranceSorbonne UniversitésParisFrance
| | | | - Thibault Peineau
- Laboratoire de Neurophysiologie de la Synapse AuditiveUniversité de BordeauxBordeauxFrance
| | - Suhasini R Gopal
- Department of Otolaryngology – Head and Neck SurgeryUniversity Hospitals Cleveland Medical CenterCase Western Reserve UniversityClevelandOHUSA
| | - Kumar N Alagramam
- Department of Otolaryngology – Head and Neck SurgeryUniversity Hospitals Cleveland Medical CenterCase Western Reserve UniversityClevelandOHUSA
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head and Neck Surgery, Anatomy and Neurobiology and Institute for Genome SciencesUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Didier Dulon
- Laboratoire de Neurophysiologie de la Synapse AuditiveUniversité de BordeauxBordeauxFrance
| | - Sara Wells
- Mary Lyon CentreMRC Harwell InstituteHarwellUK
| | - Frances M Williams
- Department of Twin Research & Genetic EpidemiologyKing's College LondonLondonUK
| | - Christine Petit
- Génétique et Physiologie de l'AuditionInstitut PasteurINSERM UMR‐S 1120Collège de FranceSorbonne UniversitésParisFrance
| | | | | | - Walter Marcotti
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Aziz El‐Amraoui
- Déficits Sensoriels ProgressifsInstitut PasteurINSERM UMR‐S 1120Sorbonne UniversitésParisFrance
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4
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Vargo JW, Walker SN, Gopal SR, Deshmukh AR, McDermott BM, Alagramam KN, Stepanyan R. Inhibition of Mitochondrial Division Attenuates Cisplatin-Induced Toxicity in the Neuromast Hair Cells. Front Cell Neurosci 2017; 11:393. [PMID: 29311828 PMCID: PMC5732985 DOI: 10.3389/fncel.2017.00393] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/28/2017] [Indexed: 12/31/2022] Open
Abstract
Cisplatin and other related platinum antineoplastic drugs are commonly used in the treatment of a variety of cancers in both adults and children but are often associated with severe side effects, including hearing loss. Cisplatin’s ototoxic effects are multifaceted, culminating in irreversible damage to the mechanosensory hair cells in the inner ear. Platinum drugs act on cancerous cells by forming nuclear DNA adducts, which may initiate signaling leading to cell cycle arrest or apoptosis. Moreover, it was reported that cisplatin may induce mitochondrial DNA damage in non-cancerous cells. Therefore, protecting mitochondria may alleviate cisplatin-induced insult to non-proliferating cells. Thus, it is important to identify agents that shield the mitochondria from cisplatin-induced insult without compromising the anti-tumor actions of the platinum-based drugs. In this study we tested the protective properties of mitochondrial division inhibitor, mdivi-1, a derivative of quinazolinone and a regulator of mitochondrial fission. Interestingly, it has been reported that mdivi-1 increases the apoptosis of cells that are resistant to cisplatin. The ability of mdivi-1 to protect hair cells against cisplatin-induced toxicity was evaluated in a fish model. Wild-type (Tübingen strain), cdh23 mutant, and transgenic pvalb3b::GFP zebrafish stably expressing GFP in the hair cells were used in this study. Larvae at 5–6 days post fertilization were placed in varying concentrations of cisplatin (50–200 μM) and/or mdivi-1 (1–10 μM) for 16 h. To evaluate hair cell’s viability the number of hair bundles per neuromast were counted. To assess hair cell function, we used the FM1-43 uptake assay and recordings of neuromast microphonic potentials. The results showed that mdivi-1 protected hair cells of lateral line neuromasts when they were challenged by 50 μM of cisplatin: viability of hair cells increased almost twice from 19% ± 1.8% to 36% ± 2.0% (p < 0.001). No protection was observed when higher concentrations of cisplatin were used. In addition, our data were in accord with previously reported results that functional mechanotransduction strongly potentiates cisplatin-induced hair cell toxicity. Together, our results suggest that mitochondrial protection may prevent cisplatin-induced damage to hair cells.
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Affiliation(s)
- Jonathon W Vargo
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, United States
| | - Steven N Walker
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, United States
| | - Suhasini R Gopal
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, United States
| | - Aditi R Deshmukh
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, United States
| | - Brian M McDermott
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, United States.,Department of Biology, Case Western Reserve University, Cleveland, OH, United States.,Department of Neurosciences, Case Western Reserve University, Cleveland, OH, United States.,Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, United States
| | - Kumar N Alagramam
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, United States.,Department of Neurosciences, Case Western Reserve University, Cleveland, OH, United States.,Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, United States
| | - Ruben Stepanyan
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, United States.,Department of Neurosciences, Case Western Reserve University, Cleveland, OH, United States
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5
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Mahendrasingam S, Fettiplace R, Alagramam KN, Cross E, Furness DN. Spatiotemporal changes in the distribution of LHFPL5 in mice cochlear hair bundles during development and in the absence of PCDH15. PLoS One 2017; 12:e0185285. [PMID: 29069081 PMCID: PMC5656302 DOI: 10.1371/journal.pone.0185285] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Accepted: 09/08/2017] [Indexed: 11/18/2022] Open
Abstract
Mechanosensory transduction by vertebrate hair cells depends on a protein complex at the tips of shorter stereocilia associated with mechanoelectrical transduction channels activated by tip links in the hair bundle. In mammalian hair cells, this complex includes transmembrane channel-like protein subunit 1 (TMC1), lipoma HMGIC fusion partner-like 5 protein (LHFPL5) and protocadherin 15 (PCDH15), a lower-end component of the tip link. TMC1 interacts with LHFPL5 and PCDH15 but how the complex develops to maturity, and the relationships between these proteins, remains uncertain. Here we evaluate the spatiotemporal development of LHFPL5 distributions in mouse cochlear hair bundles by immunofluorescence and immunogold transmission electron microscopy, from postnatal day 0 (P0) through P21 in wild type and PCDH15-deficient mice. At P0, hair bundles contain many short microvilli-like processes which we term unranked stereocilia, and a subset of lengthening rows, adjacent to a kinocilium. LHFPL5 is distributed throughout the bundle, including on stereocilia tips and the kinocilium. At P3, 4-to-6 rows of ranked stereocilia are evident, total LHFPL5 expression peaks, and LHFPL5 is localised to ranked stereocilia tips of all rows and to lower shaft/ankle links. By P12, the bundle has a mature pattern with 3 ranked rows but virtually no unranked stereocilia or kinocilium; LHFPL5 expression has declined and become restricted to the tips of shorter stereocilia. Throughout development from P0, expression of LHFPL5 is greater overall on apical than basal bundles, but there is, on average, an equal amount of labelling per labelled tip. In P3 mice lacking PCDH15, LHFPL5 labelling is not at the tips but is primarily on unranked stereocilia and lower lateral links. These data show that LHFPL5 is already present in the MET apparatus at P0 but requires PCDH15 at P3 to remain there. Shaft/ankle link localisation suggests it interacts with link proteins other than PCDH15.
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Affiliation(s)
| | - Robert Fettiplace
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, WI, United States of America
| | - Kumar N. Alagramam
- Otolaryngology Head and Neck Surgery, University Hospital Cleveland Medical Center, Case Western Reserve University, Cleveland, Ohio, OH, United States of America
| | - Ellen Cross
- School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - David N. Furness
- School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
- * E-mail:
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6
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Alagramam KN, Gopal SR, Geng R, Chen DHC, Nemet I, Lee R, Tian G, Miyagi M, Malagu KF, Lock CJ, Esmieu WRK, Owens AP, Lindsay NA, Ouwehand K, Albertus F, Fischer DF, Bürli RW, MacLeod AM, Harte WE, Palczewski K, Imanishi Y. A small molecule mitigates hearing loss in a mouse model of Usher syndrome III. Nat Chem Biol 2016; 12:444-51. [PMID: 27110679 PMCID: PMC4871731 DOI: 10.1038/nchembio.2069] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 03/08/2016] [Indexed: 12/30/2022]
Abstract
Usher syndrome type III (USH3), characterized by progressive deafness, variable balance disorder and blindness, is caused by destabilizing mutations in the gene encoding the clarin-1 (CLRN1) protein. Here we report a new strategy to mitigate hearing loss associated with a common USH3 mutation CLRN1(N48K) that involves cell-based high-throughput screening of small molecules capable of stabilizing CLRN1(N48K), followed by a secondary screening to eliminate general proteasome inhibitors, and finally an iterative process to optimize structure-activity relationships. This resulted in the identification of BioFocus 844 (BF844). To test the efficacy of BF844, we developed a mouse model that mimicked the progressive hearing loss associated with USH3. BF844 effectively attenuated progressive hearing loss and prevented deafness in this model. Because the CLRN1(N48K) mutation causes both hearing and vision loss, BF844 could in principle prevent both sensory deficiencies in patients with USH3. Moreover, the strategy described here could help identify drugs for other protein-destabilizing monogenic disorders.
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Affiliation(s)
- Kumar N Alagramam
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, USA.,Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio, USA.,Neurosciences, Case Western Reserve University, Cleveland, Ohio, USA
| | - Suhasini R Gopal
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, USA
| | - Ruishuang Geng
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, USA
| | - Daniel H-C Chen
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, USA
| | - Ina Nemet
- Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Richard Lee
- Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Guilian Tian
- Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Masaru Miyagi
- Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, Ohio, USA
| | - Karine F Malagu
- BioFocus, a Charles River company, Chesterford Research Park, Saffron Walden, UK
| | - Christopher J Lock
- BioFocus, a Charles River company, Chesterford Research Park, Saffron Walden, UK
| | - William R K Esmieu
- BioFocus, a Charles River company, Chesterford Research Park, Saffron Walden, UK
| | - Andrew P Owens
- BioFocus, a Charles River company, Chesterford Research Park, Saffron Walden, UK
| | - Nicola A Lindsay
- BioFocus, a Charles River company, Chesterford Research Park, Saffron Walden, UK
| | | | | | | | - Roland W Bürli
- BioFocus, a Charles River company, Chesterford Research Park, Saffron Walden, UK
| | - Angus M MacLeod
- BioFocus, a Charles River company, Chesterford Research Park, Saffron Walden, UK
| | - William E Harte
- Office of Translation and Innovation, Case Western Reserve University, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Yoshikazu Imanishi
- Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, Ohio, USA
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7
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Alagramam KN, Stepanyan R, Jamesdaniel S, Chen DHC, Davis RR. Noise exposure immediately activates cochlear mitogen-activated protein kinase signaling. Noise Health 2015; 16:400-9. [PMID: 25387536 DOI: 10.4103/1463-1741.144418] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Noise-induced hearing loss (NIHL) is a major public health issue worldwide. Uncovering the early molecular events associated with NIHL would reveal mechanisms leading to the hearing loss. Our aim is to investigate the immediate molecular responses after different levels of noise exposure and identify the common and distinct pathways that mediate NIHL. Previous work showed mice exposed to 116 decibels sound pressure level (dB SPL) broadband noise for 1 h had greater threshold shifts than the mice exposed to 110 dB SPL broadband noise, hence we used these two noise levels in this study. Groups of 4-8-week-old CBA/CaJ mice were exposed to no noise (control) or to broadband noise for 1 h, followed by transcriptome analysis of total cochlear RNA isolated immediately after noise exposure. Previously identified and novel genes were found in all data sets. Following exposure to noise at 116 dB SPL, the earliest responses included up-regulation of 243 genes and down-regulation of 61 genes, while a similar exposure at 110 dB SPL up-regulated 155 genes and down-regulated 221 genes. Bioinformatics analysis indicated that mitogen-activated protein kinase (MAPK) signaling was the major pathway in both levels of noise exposure. Nevertheless, both qualitative and quantitative differences were noticed in some MAPK signaling genes, after exposure to different noise levels. Cacna1b , Cacna1g , and Pla2g6 , related to calcium signaling were down-regulated after 110 dB SPL exposure, while the fold increase in the expression of Fos was relatively lower than what was observed after 116 dB SPL exposure. These subtle variations provide insight on the factors that may contribute to the differences in NIHL despite the activation of a common pathway.
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Affiliation(s)
- Kumar N Alagramam
- Department of Otolaryngology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH 44106, USA
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8
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Gerka-Stuyt J, Au A, Peachey NS, Alagramam KN. Transient receptor potential melastatin 1: a hair cell transduction channel candidate. PLoS One 2013; 8:e77213. [PMID: 24146970 PMCID: PMC3795643 DOI: 10.1371/journal.pone.0077213] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 09/03/2013] [Indexed: 11/29/2022] Open
Abstract
Sound and head movements are perceived through sensory hair cells in the inner ear. Mounting evidence indicates that this process is initiated by the opening of mechanically sensitive calcium-permeable channels, also referred to as the mechanoelectrical transducer (MET) channels, reported to be around the tips of all but the tallest stereocilia. However, the identity of MET channel remains elusive. Literature suggests that the MET channel is a non-selective cation channel with a high Ca2+ permeability and ∼100 picosiemens conductance. These characteristics make members of the transient receptor potential (TRP) superfamily likely candidates for this role. One of these candidates is the transient receptor potential melastatin 1 protein (TRPM1), which is expressed in various cells types within the cochlea of the mouse including the hair cells. Recent studies demonstrate that mutations in the TRPM1 gene underlie the inherited retinal disease complete congenital stationary night blindness in humans and depolarizing bipolar cell dysfunction in the mouse retina, but auditory function was not assessed. Here we investigate the role of Trpm1 in hearing and as a possible hair cell MET channel using mice homozygous for the null allele of Trpm1 (Trpm1−/−) or a missense mutation in the pore domain of TRPM1 (Trpm1tvrm27/tvrm27). Hearing thresholds were evaluated in adult (4–5 months old) mice with auditory-evoked brain stem responses. Our data shows no statistically significant difference in hearing thresholds in Trpm1−/− or Trpm1tvrm27/tvrm27 mutants compared to littermate controls. Further, none of the mutant mice showed any sign of balance disorder, such as head bobbing or circling. These data suggest that TRPM1 is not essential for development of hearing or balance and it is unlikely that TRPM1 is a component of the hair cell MET channel.
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Affiliation(s)
- John Gerka-Stuyt
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Adrian Au
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Neal S. Peachey
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States of America
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Kumar N. Alagramam
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
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Alagramam KN, Goodyear RJ, Geng R, Furness DN, van Aken AFJ, Marcotti W, Kros CJ, Richardson GP. Mutations in protocadherin 15 and cadherin 23 affect tip links and mechanotransduction in mammalian sensory hair cells. PLoS One 2011; 6:e19183. [PMID: 21532990 PMCID: PMC3080917 DOI: 10.1371/journal.pone.0019183] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 03/29/2011] [Indexed: 11/26/2022] Open
Abstract
Immunocytochemical studies have shown that protocadherin-15 (PCDH15) and cadherin-23 (CDH23) are associated with tip links, structures thought to gate the mechanotransducer channels of hair cells in the sensory epithelia of the inner ear. The present report describes functional and structural analyses of hair cells from Pcdh15av3J (av3J), Pcdh15av6J (av6J) and Cdh23v2J (v2J) mice. The av3J and v2J mice carry point mutations that are predicted to introduce premature stop codons in the transcripts for Pcdh15 and Cdh23, respectively, and av6J mice have an in-frame deletion predicted to remove most of the 9th cadherin ectodomain from PCDH15. Severe disruption of hair-bundle morphology is observed throughout the early-postnatal cochlea in av3J/av3J and v2J/v2J mice. In contrast, only mild-to-moderate bundle disruption is evident in the av6J/av6J mice. Hair cells from av3J/av3J mice are unaffected by aminoglycosides and fail to load with [3H]-gentamicin or FM1-43, compounds that permeate the hair cell's mechanotransducer channels. In contrast, hair cells from av6J/av6J mice load with both FM1-43 and [3H]-gentamicin, and are aminoglycoside sensitive. Transducer currents can be recorded from hair cells of all three mutants but are reduced in amplitude in all mutants and have abnormal directional sensitivity in the av3J/av3J and v2J/v2J mutants. Scanning electron microscopy of early postnatal cochlear hair cells reveals tip-link like links in av6J/av6J mice, substantially reduced numbers of links in the av3J/av3J mice and virtually none in the v2J/v2J mice. Analysis of mature vestibular hair bundles reveals an absence of tip links in the av3J/av3J and v2J/v2J mice and a reduction in av6J/av6J mice. These results therefore provide genetic evidence consistent with PCDH15 and CDH23 being part of the tip-link complex and necessary for normal mechanotransduction.
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Affiliation(s)
- Kumar N. Alagramam
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Richard J. Goodyear
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
| | - Ruishuang Geng
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - David N. Furness
- Institute for Science and Technology in Medicine, School of Life Sciences, Keele University, Staffordshire, United Kingdom
| | | | - Walter Marcotti
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - Corné J. Kros
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
- * E-mail: (CJK); (GPR)
| | - Guy P. Richardson
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
- * E-mail: (CJK); (GPR)
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Melki SJ, Heddon CM, Frankel JK, Levitt AH, Momin SR, Alagramam KN, Megerian CA. Pharmacological protection of hearing loss in the mouse model of endolymphatic hydrops. Laryngoscope 2010; 120:1637-45. [PMID: 20641076 DOI: 10.1002/lary.21018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVES/HYPOTHESIS Excitotoxic and related inflammatory injury are implicated in the spiral ganglion degeneration seen with Meniere's disease and endolymphatic hydrops (ELH). Excitotoxicity is initiated with glutamate elevation and associated with downstream increases in reactive oxygen species resulting in inflammation-mediated neuronal degeneration. This study tests the hypothesis that interruption of the initial and/or downstream aspects of excitotoxicity should provide hearing protection in ELH-associated hearing loss. STUDY DESIGN This study tests whether riluzole, a glutamate release inhibitor, and dimethylsulfoxide (DMSO), an anti-inflammatory and antioxidant solvent with favorable properties at the level of glutamate receptors, can protect against early-stage hearing loss in a mouse model of ELH. METHODS The Phex(Hyp-Duk) mouse spontaneously develops ELH and postnatal hearing loss. Starting at postnatal day 6 (P6), daily injections of riluzole + DMSO or just DMSO were administered. Untreated mutants served as controls. At P21, P25, and P30, hearing function was assessed by recording auditory brainstem responses. A cochlear function index was developed to assess global cochlear function at each time point. RESULTS Compared to no treatment, DMSO provided significant hearing protection (P < .05). The riluzole + DMSO also showed protection, but it was statistically indistinguishable from DMSO alone; a synergistic increase in protection with riluzole was not observed. CONCLUSIONS This study demonstrates pharmacological hearing protection in an animal model of ELH. The results support the assertion that inflammatory (reactive oxygen species) injury, which is part of the excitotoxic pathway, contributes to the development of ELH-associated hearing loss.
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Affiliation(s)
- Sami J Melki
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, USA
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11
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Lee RG, Vecchiotti MA, Heaphy J, Panneerselvam A, Schluchter MD, Oleinick NL, Lavertu P, Alagramam KN, Arnold JE, Sprecher RC. Photodynamic therapy of cottontail rabbit papillomavirus-induced papillomas in a severe combined immunodeficient mouse xenograft system. Laryngoscope 2010; 120:618-24. [PMID: 20091778 DOI: 10.1002/lary.20709] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVES/HYPOTHESIS To evaluate the efficacy of photodynamic therapy (PDT) with the phthalocyanine photosensitizer Pc 4 for treating an animal model of recurrent respiratory papillomatosis (RRP). METHODS Rabbit skin was grafted onto the dorsum of severe combined immunodeficient mice, two xenografts per animal. After the graft healed, it was inoculated with cottontail rabbit papillomavirus (CRPV). When papillomas developed, Pc 4 (0.6 or 1.0 mg/kg) was administered systemically, and 48 hours later, one papilloma of the two on each animal was exposed to 675-nm photoactivating light at either 100 or 150 J/cm(2). In addition to the contralateral tumors, which received Pc 4 but no light, other controls included animals receiving light only or neither agent. Response was assessed by measuring papilloma size with a caliper. Some papillomas and residual skin were harvested for histological assessment. RESULTS For the lower-dose PDT regimens, papilloma growth rates were not significantly different from the controls. In contrast, 13 of 15 papillomas receiving the higher Pc 4 dose (1.0 mg/kg) and the higher light fluence (150 J/cm(2)) regressed completely and did not regrow within the observation period of up to 79 days. The response of these papillomas was significantly different from the controls (P < .001). Histological analysis confirmed the absence of residual tumor following complete response and replacement with near-normal epithelium. CONCLUSIONS Pc 4-PDT is highly effective in treating virally induced (CRPV) papillomas in a murine model of RRP, and thus warrants further study as a treatment for HPV-induced papillomas.
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Affiliation(s)
- Richard G Lee
- Department of Otolaryngology, Head and Neck Surgery, Case Western Reserve University, Cleveland, Ohio 44106, USA
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12
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Abstract
OBJECTIVES/HYPOTHESIS Neuronal toxicity is thought to be important in Meniere's disease and experimental endolymphatic hydrops (ELH). This study quantifies the relationship between neuronal degeneration and hair cell degeneration in ELH to evaluate the hypothesis that a primary neural insult would yield greater loss in the spiral ganglion than at the inner hair cell level. STUDY DESIGN Following induction and histopathologic confirmation of endolymphatic hydrops in guinea pigs, the degree of hydrops, spiral ganglion loss, and hair cell degeneration were quantified and compared. METHODS Guinea pigs with surgically induced unilateral hydrops were sacrificed and their cochleas preserved. Hydrops severity and spiral ganglion density were quantified using automated methods. Hair cells were counted manually. Values were normalized against the contralateral ear to create loss indexes. RESULTS Inner hair cell (IHC) loss at the apex is significantly lower than corresponding neuronal loss. IHC loss at the base is also lower than neuron loss, although not significantly. Regression analysis shows a significant, positive correlation between neuron loss severity and IHC loss severity at the apex, but not at the base. There is no correlation between hydrops severity and inner hair cell loss. CONCLUSIONS By confirming that spiral ganglion loss is more severe than hair cell loss, and that hair cell loss appears to worsen with neuronal degeneration, this study supports the theory that neuronal toxicity is the primary insult in ELH-related disorders, such as Meniere's disease, and may provide the basis for designing treatment strategies.
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Affiliation(s)
- Suhael R Momin
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University, University Hospitals Case Medical Center, Cleveland, Ohio 44106, USA
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13
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Huertas-Vazquez A, Plaisier CL, Geng R, Haas BE, Lee J, Greevenbroek MM, van der Kallen C, de Bruin TWA, Taskinen MR, Alagramam KN, Pajukanta P. A nonsynonymous SNP within PCDH15 is associated with lipid traits in familial combined hyperlipidemia. Hum Genet 2009; 127:83-9. [PMID: 19816713 PMCID: PMC2793376 DOI: 10.1007/s00439-009-0749-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 09/21/2009] [Indexed: 12/20/2022]
Abstract
Familial combined hyperlipidemia (FCHL) is a common lipid disorder characterized by the presence of multiple lipoprotein phenotypes that increase the risk of premature coronary heart disease. In a previous study, we identified an intragenic microsatellite marker within the protocadherin 15 (PCDH15) gene to be associated with high triglycerides (TGs) in Finnish dyslipidemic families. In this study we analyzed all four known nonsynonymous SNPs within PCDH15 in 1,268 individuals from Finnish and Dutch multigenerational families with FCHL. Association analyses of quantitative traits for SNPs were performed using the QTDT test. The nonsynonymous SNP rs10825269 resulted in a P = 0.0006 for the quantitative TG trait. Additional evidence for association was observed with the same SNP for apolipoprotein B levels (apo-B) (P = 0.0001) and total cholesterol (TC) levels (P = 0.001). None of the other three SNPs tested showed a significant association with any lipid-related trait. We investigated the expression of PCDH15 in different human tissues and observed that PCDH15 is expressed in several tissues including liver and pancreas. In addition, we measured the plasma lipid levels in mice with loss-of-function mutations in Pcdh15 (Pcdh15(av-Tg) and Pcdh15(av-3J)) to investigate possible abnormalities in their lipid profile. We observed a significant difference in plasma TG and TC concentrations for the Pcdh15(av-3J) carriers when compared with the wild type (P = 0.013 and P = 0.044, respectively). Our study suggests that PCDH15 is associated with lipid abnormalities.
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Alagramam KN, Brown SDM, Davis RR, Johnson KR, Jones SM, Macauley JB, Zheng QY, Zuo J. Foreword for special issue: mouse models for hearing research. Brain Res 2009; 1277:1-2. [PMID: 19540992 DOI: 10.1016/j.brainres.2009.05.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Tian G, Zhou Y, Hajkova D, Miyagi M, Dinculescu A, Hauswirth WW, Palczewski K, Geng R, Alagramam KN, Isosomppi J, Sankila EM, Flannery JG, Imanishi Y. Clarin-1, encoded by the Usher Syndrome III causative gene, forms a membranous microdomain: possible role of clarin-1 in organizing the actin cytoskeleton. J Biol Chem 2009; 284:18980-93. [PMID: 19423712 DOI: 10.1074/jbc.m109.003160] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Clarin-1 is the protein product encoded by the gene mutated in Usher syndrome III. Although the molecular function of clarin-1 is unknown, its primary structure predicts four transmembrane domains similar to a large family of membrane proteins that include tetraspanins. Here we investigated the role of clarin-1 by using heterologous expression and in vivo model systems. When expressed in HEK293 cells, clarin-1 localized to the plasma membrane and concentrated in low density compartments distinct from lipid rafts. Clarin-1 reorganized actin filament structures and induced lamellipodia. This actin-reorganizing function was absent in the modified protein encoded by the most prevalent North American Usher syndrome III mutation, the N48K form of clarin-1 deficient in N-linked glycosylation. Proteomics analyses revealed a number of clarin-1-interacting proteins involved in cell-cell adhesion, focal adhesions, cell migration, tight junctions, and regulation of the actin cytoskeleton. Consistent with the hypothesized role of clarin-1 in actin organization, F-actin-enriched stereocilia of auditory hair cells evidenced structural disorganization in Clrn1(-/-) mice. These observations suggest a possible role for clarin-1 in the regulation and homeostasis of actin filaments, and link clarin-1 to the interactive network of Usher syndrome gene products.
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Affiliation(s)
- Guilian Tian
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106-4965, USA
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16
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Geng R, Geller SF, Hayashi T, Ray CA, Reh TA, Bermingham-McDonogh O, Jones SM, Wright CG, Melki S, Imanishi Y, Palczewski K, Alagramam KN, Flannery JG. Usher syndrome IIIA gene clarin-1 is essential for hair cell function and associated neural activation. Hum Mol Genet 2009; 18:2748-60. [PMID: 19414487 DOI: 10.1093/hmg/ddp210] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Usher syndrome 3A (USH3A) is an autosomal recessive disorder characterized by progressive loss of hearing and vision due to mutation in the clarin-1 (CLRN1) gene. Lack of an animal model has hindered our ability to understand the function of CLRN1 and the pathophysiology associated with USH3A. Here we report for the first time a mouse model for ear disease in USH3A. Detailed evaluation of inner ear phenotype in the Clrn1 knockout mouse (Clrn1(-/-)) coupled with expression pattern of Clrn1 in the inner ear are presented here. Clrn1 was expressed as early as embryonic day 16.5 in the auditory and vestibular hair cells and associated ganglionic neurons, with its expression being higher in outer hair cells (OHCs) than inner hair cells. Clrn1(-/-) mice showed early onset hearing loss that rapidly progressed to severe levels. Two to three weeks after birth (P14-P21), Clrn1(-/-) mice showed elevated auditory-evoked brainstem response (ABR) thresholds and prolonged peak and interpeak latencies. By P21, approximately 70% of Clrn1(-/-) mice had no detectable ABR and by P30 these mice were deaf. Distortion product otoacoustic emissions were not recordable from Clrn1(-/-) mice. Vestibular function in Clrn1(-/-) mice mirrored the cochlear phenotype, although it deteriorated more gradually than cochlear function. Disorganization of OHC stereocilia was seen as early as P2 and by P21 OHC loss was observed. In sum, hair cell dysfunction and prolonged peak latencies in vestibular and cochlear evoked potentials in Clrn1(-/-) mice strongly indicate that Clrn1 is necessary for hair cell function and associated neural activation.
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Affiliation(s)
- Ruishuang Geng
- Department of Otolaryngology Head & Neck Surgery, Case Western Reserve University, Cleveland, OH 44106, USA
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Megerian CA, Semaan MT, Aftab S, Kisley LB, Zheng QY, Pawlowski KS, Wright CG, Alagramam KN. A mouse model with postnatal endolymphatic hydrops and hearing loss. Hear Res 2008; 237:90-105. [PMID: 18289812 PMCID: PMC2858221 DOI: 10.1016/j.heares.2008.01.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 12/18/2007] [Accepted: 01/04/2008] [Indexed: 10/22/2022]
Abstract
Endolymphatic hydrops (ELH), hearing loss and neuronal degeneration occur together in a variety of clinically significant disorders, including Meniere's disease (MD). However, the sequence of these pathological changes and their relationship to each other are not well understood. In this regard, an animal model that spontaneously develops these features postnatally would be useful for research purposes. A search for such a model led us to the Phex Hyp-Duk mouse, a mutant allele of the Phex gene causing X-linked hypophosphatemic rickets. The hemizygous male (Phex Hyp-Duk/Y) was previously reported to exhibit various abnormalities during adulthood, including thickening of bone, ELH and hearing loss. The reported inner-ear phenotype was suggestive of progressive pathology and spontaneous development of ELH postnatally, but not conclusive. The main focuses of this report are to further characterize the inner ear phenotype in Phex Hyp-Duk/Y mice and to test the hypotheses that (a) the Phex Hyp-Duk/Y mouse develops ELH and hearing loss postnatally, and (b) the development of ELH in the Phex Hyp-Duk/Y mouse is associated with obstruction of the endolymphatic duct (ED) due to thickening of the surrounding bone. Auditory brainstem response (ABR) recordings at various times points and histological analysis of representative temporal bones reveal that Phex Hyp-Duk/Y mice typically develop adult onset, asymmetric, progressive hearing loss closely followed by the onset of ELH. ABR and histological data show that functional degeneration precedes structural degeneration. The major degenerative correlate of hearing loss and ELH in the mutants is the primary loss of spiral ganglion cells. Further, Phex Hyp-Duk/Y mice develop ELH without evidence of ED obstruction, supporting the idea that ELH can be induced by a mechanism other than the blockade of longitudinal flow of endolymphatic fluid, and occlusion of ED is not a prerequisite for the development of ELH in patients.
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MESH Headings
- Animals
- Disease Models, Animal
- Ear, Inner/pathology
- Ear, Inner/physiopathology
- Endolymphatic Duct/pathology
- Endolymphatic Duct/physiopathology
- Evoked Potentials, Auditory, Brain Stem
- Female
- Hearing Loss, Sensorineural/genetics
- Hearing Loss, Sensorineural/pathology
- Hearing Loss, Sensorineural/physiopathology
- Male
- Meniere Disease/genetics
- Meniere Disease/pathology
- Meniere Disease/physiopathology
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Mutant Strains
- PHEX Phosphate Regulating Neutral Endopeptidase/genetics
- Phenotype
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Affiliation(s)
- Cliff A. Megerian
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University, University Hospitals-Case Medical Center, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Maroun T. Semaan
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University, University Hospitals-Case Medical Center, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Saba Aftab
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University, University Hospitals-Case Medical Center, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Lauren B. Kisley
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University, University Hospitals-Case Medical Center, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Qing Yin Zheng
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University, University Hospitals-Case Medical Center, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Karen S. Pawlowski
- Otolaryngology-Head and Neck Surgery, University of Texas, Southwestern Medical Center, Dallas, TX 75390, USA
| | - Charles G. Wright
- Otolaryngology-Head and Neck Surgery, University of Texas, Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kumar N. Alagramam
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University, University Hospitals-Case Medical Center, 11100 Euclid Avenue, Cleveland, OH 44106, USA
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Kikkawa YS, Pawlowski KS, Wright CG, Alagramam KN. Development of Outer Hair Cells in Ames Waltzer Mice: Mutation in Protocadherin 15 Affects Development of Cuticular Plate and Associated Structures. Anat Rec (Hoboken) 2008; 291:224-32. [DOI: 10.1002/ar.20632] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
HYPOTHESIS Hearing loss and cochlear degeneration in the guinea pig model of endolymphatic hydrops (ELH) results, in part, from toxic levels of excitatory amino acids (EAAs) such as glutamate, which in turn leads to changes in the expression of genes linked to intracellular glutamate homeostasis and apoptosis, leading to neuronal cell death. BACKGROUND EAAs have been shown to play a role in normal auditory signal transmission in mammalian cochlea, but have also been implicated in neurotoxicity when levels are elevated. Changes in the expression of specific genes involved in the glutamatergic and apoptotic pathway would serve as evidence for excitotoxicity linked to elevated levels of glutamate. METHODS Guinea pigs underwent surgical obliteration of the endolymphatic duct, and then a timed harvest of the treated (right) and control (left) cochlea and subsequent quantification of gene expression via real-time quantitative polymerase chain reaction. RESULTS Quantitative polymerase chain reaction data show significant upregulation of glutamate aspartate transporter and neuronal nitric oxide synthase mRNA levels 3 weeks postsurgery and Caspase 3 mRNA levels 1 week postsurgery. No significant changes were detected in glutamine synthetase expression levels. CONCLUSION Upregulation of genes involved in glutamate homeostasis and the apoptotic pathway in animals treated with endolymphatic duct obstruction (usually associated with secondary ELH) support the hypothesis that EAAs may play a role in the pathophysiology of ELH-related cochlear injury. Inhibitors to these pathways can be useful for the study of new avenues to delay or prevent ELH-related hearing loss.
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Affiliation(s)
- Samantha Anne
- Otolaryngology-Head and Neck Surgery, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, Ohio 44106, USA
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Alagramam KN, Miller ND, Adappa ND, Pitts DR, Heaphy JC, Yuan H, Smith RJ. Promoter, alternative splice forms, and genomic structure of protocadherin 15. Genomics 2007; 90:482-92. [PMID: 17706913 PMCID: PMC2043478 DOI: 10.1016/j.ygeno.2007.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Revised: 05/31/2007] [Accepted: 06/20/2007] [Indexed: 10/22/2022]
Abstract
We originally showed that the protocadherin 15 gene (Pcdh15) is necessary for hearing and balance functions; mutations in Pcdh15 affect hair cell development in Ames waltzer (av) mice. Here we extend that study to understand better how Pcdh15 operates in a cell. The original report identified 33 exons in Pcdh15, with exon 1 being noncoding; additional exons of Pcdh15 have since been reported. The 33 exons of Pcdh15 described originally are embedded in 409 kb of mouse genomic sequence, while the corresponding exons of human PCDH15 are spread over 980 kb of genomic DNA; the exons in Pcdh15/PCDH15 range in size from 9 to approximately 2000 bp. The genomic organization of Pcdh15/PCDH15 bears similarity to that of cadherin 23, but differs significantly from other protocadherin genes, such as Pcdhalpha, beta, or gamma. A CpG island is located approximately 2900 bp upstream of the PCDH15 transcriptional start site. The Pcdh15/PCDH15 promoter lacks TATAA or CAAT sequences within 100 bases upstream of the transcription start site; deletion mapping showed that Pcdh15 harbors suppressor and enhancer elements. Preliminary searches for alternatively spliced transcripts of Pcdh15 identified novel splice variants not reported previously. Results from our study show that both mouse and human protocadherin 15 genes have complex genomic structures and transcription control mechanisms.
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Affiliation(s)
- Kumar N Alagramam
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals of Cleveland, Case Western Reserve University, Cleveland, OH 44106, USA.
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Abstract
Otitis media (OM) accounts for more than 20 million clinic visits in the United States every year. Resistance to antibiotics has hampered current management of the disease. Identification of genetic factors underlying susceptibility to OM is greatly needed in order to develop alternative treatment strategies. Genetically defined inbred mouse strains offer a powerful tool for dissecting genetic and environmental factors that may lead to OM in mice. Here, we report a study of middle ear function of 61 genetically diverse inbred strains of mice using tympanometry. Of the 61 inbred strains tested, the 129P1/ReJ, 129P3/J, 129S1/SvImJ, 129X1/SvJ, A/HeJ, BALB/cJ, BUB/BnJ, C57L/J, EL/SuzSeyFrkJ, FVB/NJ, I/LnJ, LP/J, NZB/BlNJ, PL/J and YBR/Ei strains exhibited tympanograms that were statistically different from other healthy strains according to parameters including middle ear pressure, volume and compliance. These differences are most likely the result of genetic factors that, when understood, will facilitate prevention and treatment of otitis media in humans. In addition, a negative correlation between age and compliance of the tympanic membrane was discovered. This is the first report to successfully use tympanometry to measure mouse middle ear function, which has been a challenge for the hearing research field because of the mouse's tiny ear size.
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Affiliation(s)
- Qing Yin Zheng
- Department of Otolaryngology Head and Neck Surgery, Case Western Reserve University, 11100 Euclid Avenue, LKS 5045, Cleveland, OH 44106, USA.
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22
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Davis RR, Kuo MW, Stanton SG, Canlon B, Krieg E, Alagramam KN. N-Acetyl l-cysteine does not protect against premature age-related hearing loss in C57BL/6J mice: A pilot study. Hear Res 2007; 226:203-8. [PMID: 16930891 DOI: 10.1016/j.heares.2006.07.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 06/30/2006] [Accepted: 07/03/2006] [Indexed: 10/24/2022]
Abstract
A compound capable of preventing age-related hearing loss would be very useful in an aging population. N-acetyl-L-cysteine (L-NAC) has been shown to be protective against noise exposure, a condition that leads to increased oxidative stress. Not withstanding environmental factors, there is evidence that age-related hearing loss (AHL) in the mouse is linked to more than one genetic loci and, by extension, in humans. Our hypothesis is that AHL defect results in increased sensitivity to oxidative stress and L-NAC would be able to protect the hearing of a mouse model of pre-mature AHL, the C57BL/6J (B6) mouse strain. L-NAC was added to the regular water bottle of B6 mice (experimental group) and available ad lib. The other group received normal tap water. Hearing was tested monthly by the ability to generate the auditory brainstem response (ABR). After the final ABR test, mice were sacrificed by an overdose of Avertin, ears were harvested and hair cell loss was quantified. There was no difference in ABR thresholds or in histopathology between the control group and the group receiving L-NAC in their drinking water. In contrast to the protective effects of L-NAC against noise-induced hearing loss, the lack of protective effect in this study may be due to (i) the dosage level; (ii) the duration of treatment; (iii) the biochemical mechanisms underlying age-induced hearing loss; or (iv) how the mouse metabolizes L-NAC.
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MESH Headings
- Acetylcysteine/pharmacology
- Aging/pathology
- Aging/physiology
- Animals
- Antioxidants/pharmacology
- Evoked Potentials, Auditory, Brain Stem/drug effects
- Female
- Hair Cells, Auditory, Inner/drug effects
- Hair Cells, Auditory, Inner/pathology
- Hair Cells, Auditory, Outer/drug effects
- Hair Cells, Auditory, Outer/pathology
- Mice
- Mice, Inbred C57BL
- Pilot Projects
- Presbycusis/pathology
- Presbycusis/physiopathology
- Presbycusis/prevention & control
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Affiliation(s)
- Rickie R Davis
- Hearing Loss Prevention Team, Engineering and Physical Hazards Branch, Division of Applied Research and Technology, National Institute for Occupational Safety and Health, C-27, 4676 Columbia Parkway, Cincinnati, OH 45226, USA.
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23
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Abstract
HYPOTHESIS The choice of ribonucleic acid (RNA) isolation protocol coupled with modifications to RNA extraction and detection procedures may result in a more reliable method to detect gene expression in archived temporal bones. BACKGROUND A large number of archival temporal bones exist. Retrospective analysis of these specimens using techniques of RNA extraction will greatly enrich our understanding of the pathophysiology of specific otologic diseases. However, archival human temporal bones are aged and embedded in paraffin or celloidin, rendering isolation and manipulation of nucleic acid in preserved specimens difficult, especially as it pertains to RNA degradation. Despite some reports of moderate success in the recent past, RNA isolation and gene expression using polymerase chain reaction (PCR) analysis continues to be challenging and unreliable. Archival guinea pig temporal bone specimens were used to develop and optimize a protocol for RNA extraction and gene expression analysis using PCR and quantitative PCR methods. The genes amplified comprise housekeeping genes and genes associated with the glutamate pathway. METHODS Archival celloidin-embedded guinea pig temporal bones were collected from the senior author's collection of experimental hydropic inner ear specimens. RNA from this tissue was extracted using the protocol described previously in 16animals and using a modified trizol extraction technique in 10 animals. Gene expression analysis was performed on the extracted RNA. Analysis included two housekeeping genes, GAPDH and 18S, as well as three mediators of the glutamate pathway, glutamate aspartate transporter, glutamate synthetase, and inducible nitric oxide synthase. RESULTS Compared with the standard extraction protocol, the trizol-based extraction technique showed greater reliability and reproducibility of RNA detection. The housekeeping gene GAPDH or 18S was detected in 7 of 36 attempts with the standard protocol versus 9 of 9 using the modified extraction method (P < 0.001). The gene of interest, glutamate aspartate transporter, was detected in 3 of 26 attempts with the standard protocol versus 12 of 13 attempts using the modified extraction method (P < 0.001). Quantification of messenger RNA levels was then achieved using quantitative PCR methods. CONCLUSION Improved reliability for detection of gene expression and demonstration of reproducibility were accomplished by modification of RNA extraction technique and standard reverse transcriptase PCR protocol. In addition, we also showed that gene expression from archival material can be quantified by real-time PCR.
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Affiliation(s)
- Kathryn L Hall
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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24
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Yerukhimovich MV, Bai L, Chen DHC, Miller RH, Alagramam KN. Identification and characterization of mouse cochlear stem cells. Dev Neurosci 2006; 29:251-60. [PMID: 17047322 DOI: 10.1159/000096415] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Accepted: 06/09/2006] [Indexed: 11/19/2022] Open
Abstract
Genetic, noise- and drug-induced loss of hair cells in the mouse and human cochlea leads to permanent hearing loss due to lack of regeneration of hair cells, which may be due to reduced numbers or loss of the regenerative ability of stem cells in the adult cochlea. We hypothesized that the mouse neonate cochlea harbors stem cells capable of differentiating into hair cells. Cells from the primary neonate cochlear culture began to proliferate and formed floating spheres after 14 days in vitro (DIV). By comparison, spheres from the primary culture of the cortex were observed after 7 DIV. Cochlear sphere cells could be passaged and the new spheres were observed after 7 DIV. Cochlear sphere cells were capable of differentiating into astrocytes and oligodendrocytes, but not neurons under the conditions tested. Cochlear sphere cells expressed Sox2 and Myo7a, but failed to show markers that are expressed exclusively in mature cochlear tissue, while cells from cortex spheres expressed Sox2 and Otx2, but not Myo7a. Our results show that cochleae from neonatal mice harbor cells capable of forming spheres and cells from these spheres appear to be better endowed to become hair cells.
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Affiliation(s)
- Michael V Yerukhimovich
- Department of Otolaryngology, Head and Neck Surgery, Case Western Reserve University, Cleveland, Ohio 44106, USA
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25
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Alagramam KN, Brown SD, Davis RR, Johnson KR, Macauley JB, Zheng QY, Zuo J. Special issue: Mouse models for hearing research. Brain Res 2006. [DOI: 10.1016/j.brainres.2006.04.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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26
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Zheng QY, Rozanas CR, Thalmann I, Chance MR, Alagramam KN. Inner ear proteomics of mouse models for deafness, a discovery strategy. Brain Res 2006; 1091:113-21. [PMID: 16600193 PMCID: PMC2853763 DOI: 10.1016/j.brainres.2006.02.069] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 02/17/2006] [Accepted: 02/21/2006] [Indexed: 10/24/2022]
Abstract
Inner ear dysfunction is often associated with defective hair cells. Therefore, hair cells are the focus of study in many of the mouse mutants showing auditory and vestibular deficits. However, harvesting sufficient numbers of hair cells from the tiny bony mouse inner ear for proteomic analysis is challenging. New approaches that would take advantage of mouse mutants and avoid processing steps, such as decalcification or microdissetion, would be more suitable for proteomic analysis. Here, we propose a novel approach called SSUMM-Subtractive Strategy Using Mouse Mutants. SSUMM takes advantage of the differences between control and affected or mutant samples. We predict that SSUMM would be a useful method in proteomics, especially in those cases in which the investigator must work with small numbers of diverse cell types from a tiny organ. Here, we discuss the potential utility of SSUMM to unravel the protein expression profiles of hair cells using the Pou4f3 mouse mutant as an example. Pou4f3 mutant mice exhibit a total loss of inner and outer hair cells, but supporting cells remain relatively intact in the cochlea, thus providing an excellent model for identifying proteins and transcripts that are specific to the hair cell at all life stages. SSUMM would maximize the sensitivity of the analyses while obviating the need for tedious sessions of microdissection and collection of hair cells. By comparing the mutant to control ears at specific time points, it is possible to identify direct targets of a gene product of interest. Further, SSUMM could be used to identify and analyze inner ear development markers and other known genes/proteins that are coexpressed in the ear. In this short technical report, we also discuss protein-profiling approaches suitable for SSUMM and briefly discuss other approaches used in the field of proteomics.
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Affiliation(s)
- Qing Yin Zheng
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609-1500, USA.
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27
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Jones SM, Johnson KR, Yu H, Erway LC, Alagramam KN, Pollak N, Jones TA. A quantitative survey of gravity receptor function in mutant mouse strains. J Assoc Res Otolaryngol 2006; 6:297-310. [PMID: 16235133 PMCID: PMC2504620 DOI: 10.1007/s10162-005-0009-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Accepted: 06/20/2005] [Indexed: 02/04/2023] Open
Abstract
The purpose of this research was to identify vestibular deficits in mice using linear vestibular evoked potentials (VsEPs). VsEP thresholds, peak latencies, and peak amplitudes from 24 strains with known genetic mutations and 6 inbred background strains were analyzed and descriptive statistics generated for each strain. Response parameters from mutant homozygotes were compared with heterozygote and/or background controls and all strain averages were contrasted to normative ranges. Homozygotes of the following recessive mutations had absent VsEPs at the ages tested: Espn(je), Atp2b2dfw-2J, Spnb4qv-lnd2J, Spnb4qv-3J, Myo7ash1, Tmie(sr), Myo6sv, jc, Pcdh15av-J, Pcdh15av-2J, Pcdh15av-3J, Cdh23v-2J, Sans(js), hr, Kcne1pkr and Pou3f4del. These results suggest profound gravity receptor deficits for these homozygotes, which is consistent with the structural deficits that have been documented for many of these strains. Homozygotes of Catna2cdf, Grid2ho4J, Wnt1sw, qk, and Mbpshi strains and heterozygotes of Grid2lc had measurable VsEPs but one or more response parameters differed from the respective control group (heterozygote or background strain) or were outside normal ranges. For example, qk and Mbpshi homozygotes showed significantly prolonged latencies consistent with the abnormal myelin that has been described for these strains. Prolonged latencies may suggest deficits in neural conduction; elevated thresholds suggest reduced sensitivity, and reduced amplitudes may be suggestive for reduced neural synchrony. One mutation, Otx1jv, had all VsEP response parameters within normal limits--an expected finding because the abnormality in Otxljv is presumably restricted to the lateral semicircular canal. Interestingly, some heterozygote groups also showed abnormalities in one or more VsEP response parameters, suggesting that vestibular dysfunction, although less severe, may be present in some heterozygous animals.
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Affiliation(s)
- Sherri M Jones
- Department of Communication Sciences and Disorders, East Carolina University, Greenville, NC 27858, USA.
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28
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Pagedar NA, Wang W, Chen DHC, Davis RR, Lopez I, Wright CG, Alagramam KN. Gene expression analysis of distinct populations of cells isolated from mouse and human inner ear FFPE tissue using laser capture microdissection--a technical report based on preliminary findings. Brain Res 2006; 1091:289-99. [PMID: 16529721 DOI: 10.1016/j.brainres.2006.01.057] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 01/10/2006] [Accepted: 01/13/2006] [Indexed: 01/22/2023]
Abstract
Laser Capture Microdissection (LCM) allows microscopic procurement of specific cell types from tissue sections that can then be used for gene expression analysis. We first tested this method with sections of adult mouse inner ears and subsequently applied it to human inner ear sections. The morphology of the various cell types within the inner ear is well preserved in formalin fixed paraffin embedded (FFPE) sections, making it easier to identify cell types and their boundaries. Recovery of good quality RNA from FFPE sections can be challenging, however, recent studies in cancer research demonstrated that it is possible to carry out gene expression analysis of FFPE material. Thus, a method developed using mouse FFPE tissue can be applied to human archival temporal bones. This is important because the majority of human temporal bone banks have specimens preserved in formalin and a technique for retrospective analysis of human archival ear tissue is needed. We used mouse FFPE inner ear sections to procure distinct populations of cells from the various functional domains (organ of Corti, spiral ganglion, etc.) by LCM. RNA was extracted from captured cells, amplified, and assessed for quality. Expression of selected genes was tested by RT-PCR. In addition to housekeeping genes, we were able to detect cell type specific markers, such as Myosin 7a, p27(kip1) and neurofilament gene transcripts that confirmed the likely composition of cells in the sample. We also tested the method described above on FFPE sections from human crista ampullaris. These sections were approximately a year old. Populations of cells from the epithelium and stroma were collected and analyzed independently for gene expression. The method described here has potential use in many areas of hearing research. For example, following exposure to noise, ototoxic drugs or age, it would be highly desirable to analyze gene expression profiles of selected populations of cells within the organ of Corti or spiral ganglion cells rather than a mixed population of cells from whole inner ear tissue. Also, this method can be applied for analysis of human archival ear tissue.
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Affiliation(s)
- Nitin A Pagedar
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals of Cleveland, Lakeside 4500, 11100 Euclid Avenue, Cleveland, OH 44106, USA
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29
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Pawlowski KS, Kikkawa YS, Wright CG, Alagramam KN. Progression of inner ear pathology in Ames waltzer mice and the role of protocadherin 15 in hair cell development. J Assoc Res Otolaryngol 2006; 7:83-94. [PMID: 16408167 PMCID: PMC2504581 DOI: 10.1007/s10162-005-0024-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2005] [Accepted: 11/30/2005] [Indexed: 11/25/2022] Open
Abstract
The Ames waltzer (av) mouse mutant exhibits auditory and vestibular abnormalities resulting from mutation of protocadherin 15 (Pcdh15). Ames waltzer has been identified as an animal model for inner ear pathology associated with Usher syndrome type 1F. Studies correlating anatomical phenotype with severity of genetic defect in various av alleles are providing better understanding of the role played by Pcdh15 in inner ear development and of sensorineural abnormalities associated with alterations in Pcdh15 protein structure as a result of gene mutation. In this work we present new findings on inner ear pathology in four alleles of av mice with differing mutations of Pcdh15 as well as varying alterations in inner ear morphology. Two alleles with in-frame deletion mutations (Pcdh15 (av-J) and Pcdh15 (av-2J)) and two presumptive functional null alleles (Pcdh15 (av-3J) and Pcdh15 (av-Tg)) were studied. Light and electron microscopic observations demonstrated that the severity of cochlear and vestibular pathology in these animals correlates positively with the extent of mutation in Pcdh15 from embryonic day 18 (E18) up to 12 months. Electron microscopic analysis of immature ears indicated early abnormalities in the arrangement of stereocilia and the inner and outer hair cell cuticular plates, stereocilia rootlets, and the actin meshwork within the cuticular plate. In severe cases, displacement of the kinocilium and alterations in the shape of the cuticular plate was also observed. Mice harboring in-frame deletion mutations showed less disorganization of stereocilia and cuticular plates in the organ of Corti than the presumptive functional null alleles at P0-P10. A slower progression of pathology was also seen via light microscopy in older animals with in-frame deletions, compared to the presumptive functional null mutations. In summary, our results demonstrate that mutation in Pcdh15 affects the initial formation of stereocilia bundles with associated changes in the actin meshwork within the cuticular plate; these effects are more pronounced in the presumed null mutation compared to mutations that only affect the extracellular domain. The positive correlation of severity of effects with extent of mutation can be seen well into adulthood.
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Affiliation(s)
- Karen S Pawlowski
- Department of Otolaryngology-Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390-9035, USA.
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30
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Abstract
PURPOSE OF REVIEW Meniere's disease is characterized by the triad of fluctuating hearing loss, episodic vertigo, and tinnitus and by endolymphatic hydrops found on post-mortem examination. The cause of Meniere's disease remains unclear. Numerous factors play a role in the development of hydrops and in the pathogenesis of related cochleovestibular dysfunction. This review highlights recent advances in the understanding of the pathophysiology of symptom development in Meniere's disease by detailing the role of genetics, autoimmunity, endolymphatic fluid homeostasis, excitotoxicity, oxidative stress, and cellular apoptosis. Emphasis is placed on reviewing the newly described animal models that exhibit endolymphatic hydrops. RECENT FINDINGS Recent evidence suggests that hearing loss might be explained in part by apoptosis of spiral ganglion neurons and that hydrops could represent an epiphenomenon rather than an initiating factor. In addition, the accepted guinea pig model described by Kimura has certain limitations. An animal model that would supplement and in some cases replace the surgically induced model is currently being sought. SUMMARY These recent advances have expanded our understanding and will allow for the development of targeted therapeutic interventions aimed at preventing the progression oochleovestibular deterioration.
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Affiliation(s)
- Maroun T Semaan
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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31
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Alagramam KN, Stahl JS, Jones SM, Pawlowski KS, Wright CG. Characterization of vestibular dysfunction in the mouse model for Usher syndrome 1F. J Assoc Res Otolaryngol 2005; 6:106-18. [PMID: 15952048 PMCID: PMC2538330 DOI: 10.1007/s10162-004-5032-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2004] [Accepted: 12/03/2004] [Indexed: 11/24/2022] Open
Abstract
The deaf-circling Ames waltzer (av) mouse harbors a mutation in the protocadherin 15 (Pcdh15) gene and is a model for inner ear defects associated with Usher syndrome type 1F. Earlier studies showed altered cochlear hair cell morphology in young av mice. In contrast, no structural abnormality consistent with significant vestibular dysfunction in young av mice was observed. Light and scanning electron microscopic studies showed that vestibular hair cells from presumptive null alleles Pcdh15(av-Tg) and Pcdh15(av-3J) are morphologically similar to vestibular sensory cells from control littermates, suggesting that the observed phenotype in these alleles might be a result of a central, rather than peripheral, defect. In the present study, a combination of physiologic and anatomic methods was used to more thoroughly investigate the source of vestibular dysfunction in Ames waltzer mice. Analysis of vestibular evoked potentials and angular vestibulo-ocular reflexes revealed a lack of physiologic response to linear and angular acceleratory stimuli in Pcdh15 mutant mice. Optokinetic reflex function was diminished but still present in the mutant animals, suggesting that the defect is primarily peripheral in nature. These findings indicate that the mutation in Pcdh15 results in either a functional abnormality in the vestibular receptor organs or that the defects are limited to the vestibular nerve. AM1-43 dye uptake has been shown to correlate with normal transduction function in hair cells. Dye uptake was found to be dramatically reduced in Pcdh15 mutants compared to control littermates, suggesting that the mutation affects hair cell function, although structural abnormalities consistent with significant vestibular dysfunction are not apparent by light and scanning electron microscopy in the vestibular neuroepithelia of young animals.
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MESH Headings
- Animals
- Cadherin Related Proteins
- Cadherins/genetics
- Coloring Agents/pharmacokinetics
- Disease Models, Animal
- Evoked Potentials, Auditory
- Fluorescent Dyes/pharmacokinetics
- Mice
- Mice, Mutant Strains
- Microscopy, Electron, Scanning
- Mutation
- Nystagmus, Optokinetic
- Protein Precursors/genetics
- Reflex, Vestibulo-Ocular
- Usher Syndromes/genetics
- Usher Syndromes/pathology
- Usher Syndromes/physiopathology
- Vestibule, Labyrinth/metabolism
- Vestibule, Labyrinth/pathology
- Vestibule, Labyrinth/physiopathology
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Affiliation(s)
- Kumar N Alagramam
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals of Cleveland, Case Western Reserve University, Cleveland, OH 44106, USA.
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Adato A, Michel V, Kikkawa Y, Reiners J, Alagramam KN, Weil D, Yonekawa H, Wolfrum U, El-Amraoui A, Petit C. Interactions in the network of Usher syndrome type 1 proteins. Hum Mol Genet 2004; 14:347-56. [PMID: 15590703 DOI: 10.1093/hmg/ddi031] [Citation(s) in RCA: 172] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Defects in myosin VIIa, harmonin (a PDZ domain protein), cadherin 23, protocadherin 15 and sans (a putative scaffolding protein), underlie five forms of Usher syndrome type I (USH1). Mouse mutants for all these proteins exhibit disorganization of their hair bundle, which is the mechanotransduction receptive structure of the inner ear sensory cells, the cochlear and vestibular hair cells. We have previously demonstrated that harmonin interacts with cadherin 23 and myosin VIIa. Here we address the extent of interactions between the five known USH1 proteins. We establish the previously suggested sans-harmonin interaction and find that sans also binds to myosin VIIa. We show that sans can form homomeric structures and that harmonin b can interact with all harmonin isoforms. We reveal that harmonin also binds to protocadherin 15. Molecular characterization of these interactions indicates that through its binding to four of the five USH1 proteins, the first PDZ domain (PDZ1) of harmonin plays a central role in this network. We localize sans in the apical region of cochlear and vestibular hair cell bodies underneath the cuticular plate. In contrast to the other four known USH1 proteins, no sans labeling was detected within the stereocilia. We propose that via its binding to myosin VIIa and/or harmonin, sans controls the hair bundle cohesion and proper development by regulating the traffic of USH1 proteins en route to the stereocilia.
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Affiliation(s)
- Avital Adato
- Unité de Génétique des Déficits Sensoriels, INSERM U587, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris cedex 15, France
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33
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Abstract
PURPOSE In humans, mutations in protocadherin 15 are known to result in Usher Syndrome type 1F (USH1F). Patients with USH1F are born with profound hearing loss and have visual problems that develop in late childhood. Based on the phenotypic hearing loss and an associated mutation in protocadherin 15 (Pcdh15), the Ames waltzer mice have been presented as potential models for USH1F. To determine whether the Ames waltzer is a model for retinopathy in USH1F, retinal structure and function were assessed in all four available alleles of the mouse. METHODS Activity of both the rod and cone pathways was evaluated by measuring electroretinograms (ERGs) in response to strobe flashes under dark- and light-adapted conditions, respectively. Retinas were processed with standard histochemical procedures, and retinal morphology was examined. The neural retina was dissected from normal pigmented mice at postnatal day (P)0, P5, P7, P20, P40, and P70, and the presence of Pcdh15 was determined by RT-PCR. RESULTS The amplitude and implicit time of both the rod- and cone-mediated ERG a- and b-waves were comparable between Ames waltzer mutants and heterozygous littermates as old as 13 months. No evidence of retinal degeneration or disorganization was detected in mutant mice. Measures of retinal layer thicknesses were similar in mutant and wild-type control animals. Retinal expression of Pcdh15 was observed at all ages examined between P0 and P70. CONCLUSIONS Although Pcdh15 is present in neural retina, its role remains unclear. Mutations in the Pcdh15 did not result in retinal abnormalities in the four alleles of Ames waltzer tested in this study. The explanation for the absence of retinal phenotype in the Ames mouse should be helpful in understanding USH1F and developing treatments for this disorder.
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Affiliation(s)
- Sherry L Ball
- Research Service, Cleveland VA Medical Center, Cleveland, Ohio, USA
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34
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Abstract
A recessive deafness mutation in the mouse arose spontaneously and was identified in a colony segregating a null allele of the gastrin-releasing peptide receptor (Grpr) locus. Auditory-evoked brain stem response measurements revealed deafness in 7-week-old affected mice. By linkage analyses, the mutant phenotype was mapped near marker D10Mit186 and the protocadherin gene Pcdh15. As shown by complementation testing, the new mutation is allelic with Ames waltzer (Pcdh15(av)). Sequencing mutant-derived brain Pcdh15 cDNAs identified the insertion of a cytosine residue at nucleotide position c2099 (2099insC), which results in a frame-shift and premature stop codon. Abnormal stereocilia on inner and outer hair cells of the organ of Corti were identified by scanning electron microscopy as early as postnatal day 0 and cross-sectional histology revealed severe neuroepithelial degeneration in cochleas of 30-50-day-old mutants. The new allele of Ames waltzer, designated Pcdh15(av-Jfb), may aid in studying the histopathology associated with Usher syndrome type 1F, which is caused by a functional null allele of PCDH15.
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Affiliation(s)
- Lori L Hampton
- G-Protein Coupled Receptors Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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35
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Alagramam KN, Yuan H, Kuehn MH, Murcia CL, Wayne S, Srisailpathy CR, Lowry RB, Knaus R, Van Laer L, Bernier FP, Schwartz S, Lee C, Morton CC, Mullins RF, Ramesh A, Van Camp G, Hageman GS, Woychik RP, Smith RJ, Hagemen GS. Mutations in the novel protocadherin PCDH15 cause Usher syndrome type 1F. Hum Mol Genet 2001; 10:1709-18. [PMID: 11487575 DOI: 10.1093/hmg/10.16.1709] [Citation(s) in RCA: 209] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have determined the molecular basis for Usher syndrome type 1F (USH1F) in two families segregating for this type of syndromic deafness. By fluorescence in situ hybridization, we placed the human homolog of the mouse protocadherin Pcdh15 in the linkage interval defined by the USH1F locus. We determined the genomic structure of this novel protocadherin, and found a single-base deletion in exon 10 in one USH1F family and a nonsense mutation in exon 2 in the second. Consistent with the phenotypes observed in these families, we demonstrated expression of PCDH15 in the retina and cochlea by RT-PCR and immunohistochemistry. This report shows that protocadherins are essential for maintenance of normal retinal and cochlear function.
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Affiliation(s)
- K N Alagramam
- Department of Pediatrics, Rainbow Babies and Children's Hospital, University Hospitals of Cleveland, Case Western Reserve University, Cleveland, OH, USA
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Alagramam KN, Murcia CL, Kwon HY, Pawlowski KS, Wright CG, Woychik RP. The mouse Ames waltzer hearing-loss mutant is caused by mutation of Pcdh15, a novel protocadherin gene. Nat Genet 2001; 27:99-102. [PMID: 11138007 DOI: 10.1038/83837] [Citation(s) in RCA: 222] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The neuroepithelia of the inner ear contain hair cells that function as mechanoreceptors to transduce sound and motion signals. Mutations affecting these neuroepithelia cause deafness and vestibular dysfuction in humans. Ames waltzer (av) is a recessive mutation found in mice that causes deafness and a balance disorder associated with the degeneration of inner ear neuroepithelia. Here we report that the gene that harbours the av mutation encodes a novel protocadherin. Cochlear hair cells in the av mutants show abnormal stereocilia by 10 days after birth (P10). This is the first evidence for the requirement of a protocadherin for normal function of the mammalian inner ear.
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Affiliation(s)
- K N Alagramam
- Department of Pediatrics, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, Ohio, USA
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Alagramam KN, Zahorsky-Reeves J, Wright CG, Pawlowski KS, Erway LC, Stubbs L, Woychik RP. Neuroepithelial defects of the inner ear in a new allele of the mouse mutation Ames waltzer. Hear Res 2000; 148:181-91. [PMID: 10978835 DOI: 10.1016/s0378-5955(00)00152-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This report presents new findings regarding a recessive insertional mutation in the transgenic line TgN2742Rpw that causes deafness and circling behavior in mice homozygous for the mutation. The mutant locus was mapped to a region on mouse chromosome 10 close to three spontaneous recessive mutations causing deafness: Ames waltzer (av), Waltzer (v), and Jackson circler (jc). Complementation testing revealed that the TgN2742Rpw mutation is allelic with av. Histological and auditory brainstem response (ABR) evaluation of animals that have the new allele balanced with the av(J) allele (called compound heterozygotes, TgN2742Rpw/av(J)) supports our genetic analysis. ABR evaluation shows complete absence of auditory response throughout the life span of TgN2742Rpw/av(J) compound heterozygotes. Scanning electron microscopy revealed abnormalities of inner and outer hair cell stereocilia in the cochleae of TgN2742Rpw mutants at 10 days after birth (DAB). The organ of Corti subsequently undergoes degeneration, leading to nearly complete loss of the cochlear neuroepithelium in older mutants by about 50 DAB. The vestibular neuroepithelia remain morphologically normal until at least 30 DAB. However, by 50 days, degenerative changes are evident in the saccular macula, which progresses to total loss of the saccular neuroepithelium in older animals. The new allele of av reported here will be designated av(TgN2742Rpw).
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Affiliation(s)
- K N Alagramam
- Department of Pediatrics, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, OH 44106, USA
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Alagramam KN, Kwon HY, Cacheiro NL, Stubbs L, Wright CG, Erway LC, Woychik RP. A new mouse insertional mutation that causes sensorineural deafness and vestibular defects. Genetics 1999; 152:1691-9. [PMID: 10430593 PMCID: PMC1460692 DOI: 10.1093/genetics/152.4.1691] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This article describes a new recessive insertional mutation in the transgenic line TgN2742Rpw that causes deafness and circling behavior in mice. Histologic analysis revealed virtually complete loss of the cochlear neuroepithelium (the organ of Corti) in adult mutant mice. In association with the neuroepithelial changes, there is a dramatic reduction of the cochlear nerve supply. Adult mutants also show morphological defects of the vestibular apparatus, including degeneration of the saccular neuroepithelium and occasional malformation of utricular otoconia. Audiometric evaluations demonstrated that the mice displaying the circling phenotype are completely deaf. Molecular analysis of this mutant line revealed that the transgenic insertion occurred without creating a large deletion of the host DNA sequences. The mutant locus was mapped to a region on mouse chromosome 10, where other spontaneous, recessive mutations causing deafness in mice have been mapped.
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Affiliation(s)
- K N Alagramam
- Department of Pediatrics, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, Ohio 44106, USA
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