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Jung J, Müller U. Mechanoelectrical transduction-related genetic forms of hearing loss. CURRENT OPINION IN PHYSIOLOGY 2023; 32:100632. [PMID: 36936795 PMCID: PMC10022594 DOI: 10.1016/j.cophys.2023.100632] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Hair cells of the mammalian cochlea are specialized mechanosensory cells that convert mechanical stimuli into electrical signals to initiate the neuronal responses that lead to the perception of sound. The mechanoelectrical transduction (MET) machinery of cochlear hair cells is a multimeric protein complex that consists of the pore forming subunits of the MET channel and several essential accessory subunits that are crucial to regulate channel function and render the channel mechanically sensitive. Mutations have been discovered in the genes that encode all known components of the MET machinery. These mutations cause hearing loss with or without vestibular dysfunction. Some mutations also affect other tissues such as the retina. In this brief review, we will summarize gene mutations that affect the MET machinery of hair cells and how the study of the affected genes has illuminated our understanding of the physiological role of the encoded proteins.
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Affiliation(s)
- Jinsei Jung
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Otorhinolaryngology, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Ulrich Müller
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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2
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Nagel-Wolfrum K, Fadl BR, Becker MM, Wunderlich KA, Schäfer J, Sturm D, Fritze J, Gür B, Kaplan L, Andreani T, Goldmann T, Brooks M, Starostik MR, Lokhande A, Apel M, Fath KR, Stingl K, Kohl S, DeAngelis MM, Schlötzer-Schrehardt U, Kim IK, Owen LA, Vetter JM, Pfeiffer N, Andrade-Navarro MA, Grosche A, Swaroop A, Wolfrum U. Expression and subcellular localization of USH1C/harmonin in human retina provides insights into pathomechanisms and therapy. Hum Mol Genet 2022; 32:431-449. [PMID: 35997788 PMCID: PMC9851744 DOI: 10.1093/hmg/ddac211] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/18/2022] [Accepted: 08/19/2022] [Indexed: 01/24/2023] Open
Abstract
Usher syndrome (USH) is the most common form of hereditary deaf-blindness in humans. USH is a complex genetic disorder, assigned to three clinical subtypes differing in onset, course and severity, with USH1 being the most severe. Rodent USH1 models do not reflect the ocular phenotype observed in human patients to date; hence, little is known about the pathophysiology of USH1 in the human eye. One of the USH1 genes, USH1C, exhibits extensive alternative splicing and encodes numerous harmonin protein isoforms that function as scaffolds for organizing the USH interactome. RNA-seq analysis of human retinae uncovered harmonin_a1 as the most abundant transcript of USH1C. Bulk RNA-seq analysis and immunoblotting showed abundant expression of harmonin in Müller glia cells (MGCs) and retinal neurons. Furthermore, harmonin was localized in the terminal endfeet and apical microvilli of MGCs, presynaptic region (pedicle) of cones and outer segments (OS) of rods as well as at adhesive junctions between MGCs and photoreceptor cells (PRCs) in the outer limiting membrane (OLM). Our data provide evidence for the interaction of harmonin with OLM molecules in PRCs and MGCs and rhodopsin in PRCs. Subcellular expression and colocalization of harmonin correlate with the clinical phenotype observed in USH1C patients. We also demonstrate that primary cilia defects in USH1C patient-derived fibroblasts could be reverted by the delivery of harmonin_a1 transcript isoform. Our studies thus provide novel insights into PRC cell biology, USH1C pathophysiology and development of gene therapy treatment(s).
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Affiliation(s)
- Kerstin Nagel-Wolfrum
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany,Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Benjamin R Fadl
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany,Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mirjana M Becker
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | | | - Jessica Schäfer
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Daniel Sturm
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany,Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Jacques Fritze
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Burcu Gür
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Lew Kaplan
- Department of Physiological Genomics, BioMedical Center, Ludwig-Maximilian University Munich, 82152 Planegg-Martinsried, Germany
| | | | - Tobias Goldmann
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Matthew Brooks
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | - Anagha Lokhande
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Melissa Apel
- Department of Ophthalmology, University Medical Centre Mainz, 55131 Mainz, Germany
| | - Karl R Fath
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany,Department of Biology, Queens College of CUNY, Kissena Blvd, Flushing, NY 11367, USA
| | - Katarina Stingl
- University Eye Hospital, Centre for Ophthalmology, University of Tubingen, 72076 Tubingen, Germany
| | - Susanne Kohl
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tubingen, 72076 Tubingen, Germany
| | - Margaret M DeAngelis
- Department of Ophthalmology and Ira G. Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University of Buffalo, NY 14209, USA
| | | | - Ivana K Kim
- Retina Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
| | - Leah A Owen
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT 84132, USA
| | - Jan M Vetter
- Department of Ophthalmology, University Medical Centre Mainz, 55131 Mainz, Germany
| | - Norbert Pfeiffer
- Department of Ophthalmology, University Medical Centre Mainz, 55131 Mainz, Germany
| | - Miguel A Andrade-Navarro
- Computational Biology and Data Mining, Institute of Organismic & Molecular Evolution Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Antje Grosche
- Department of Physiological Genomics, BioMedical Center, Ludwig-Maximilian University Munich, 82152 Planegg-Martinsried, Germany
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Uwe Wolfrum
- To whom correspondence should be addressed at: Molecular Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany. Tel: +49 6131 392 5148; E-mail:
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Grotz S, Schäfer J, Wunderlich KA, Ellederova Z, Auch H, Bähr A, Runa-Vochozkova P, Fadl J, Arnold V, Ardan T, Veith M, Santamaria G, Dhom G, Hitzl W, Kessler B, Eckardt C, Klein J, Brymova A, Linnert J, Kurome M, Zakharchenko V, Fischer A, Blutke A, Döring A, Suchankova S, Popelar J, Rodríguez-Bocanegra E, Dlugaiczyk J, Straka H, May-Simera H, Wang W, Laugwitz KL, Vandenberghe LH, Wolf E, Nagel-Wolfrum K, Peters T, Motlik J, Fischer MD, Wolfrum U, Klymiuk N. Early disruption of photoreceptor cell architecture and loss of vision in a humanized pig model of usher syndromes. EMBO Mol Med 2022; 14:e14817. [PMID: 35254721 PMCID: PMC8988205 DOI: 10.15252/emmm.202114817] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 02/04/2022] [Accepted: 02/09/2022] [Indexed: 01/17/2023] Open
Abstract
Usher syndrome (USH) is the most common form of monogenic deaf-blindness. Loss of vision is untreatable and there are no suitable animal models for testing therapeutic strategies of the ocular constituent of USH, so far. By introducing a human mutation into the harmonin-encoding USH1C gene in pigs, we generated the first translational animal model for USH type 1 with characteristic hearing defect, vestibular dysfunction, and visual impairment. Changes in photoreceptor architecture, quantitative motion analysis, and electroretinography were characteristics of the reduced retinal virtue in USH1C pigs. Fibroblasts from USH1C pigs or USH1C patients showed significantly elongated primary cilia, confirming USH as a true and general ciliopathy. Primary cells also proved their capacity for assessing the therapeutic potential of CRISPR/Cas-mediated gene repair or gene therapy in vitro. AAV-based delivery of harmonin into the eye of USH1C pigs indicated therapeutic efficacy in vivo.
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Affiliation(s)
- Sophia Grotz
- Chair of Molecular Animal Breeding and Biotechnology, LMU Munich, Munich, Germany.,Center for Innovative Medical Models, LMU Munich, Munich, Germany
| | - Jessica Schäfer
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University (JGU), Mainz, Germany
| | - Kirsten A Wunderlich
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University (JGU), Mainz, Germany
| | - Zdenka Ellederova
- Institute of Animal Physiology and Genetics, Czech Academy of Science, Libechov, Czech Republic
| | - Hannah Auch
- Chair of Molecular Animal Breeding and Biotechnology, LMU Munich, Munich, Germany.,Center for Innovative Medical Models, LMU Munich, Munich, Germany
| | - Andrea Bähr
- Center for Innovative Medical Models, LMU Munich, Munich, Germany.,Large Animal Models in Cardiovascular Research, Internal Medical Department I, TU Munich, Munich, Germany
| | - Petra Runa-Vochozkova
- Large Animal Models in Cardiovascular Research, Internal Medical Department I, TU Munich, Munich, Germany
| | - Janet Fadl
- Chair of Molecular Animal Breeding and Biotechnology, LMU Munich, Munich, Germany.,Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University (JGU), Mainz, Germany
| | - Vanessa Arnold
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University (JGU), Mainz, Germany
| | - Taras Ardan
- Institute of Animal Physiology and Genetics, Czech Academy of Science, Libechov, Czech Republic
| | - Miroslav Veith
- Ophthalmology Clinic, University Hospital Kralovske Vinohrady, Praha, Czech Republic
| | - Gianluca Santamaria
- Large Animal Models in Cardiovascular Research, Internal Medical Department I, TU Munich, Munich, Germany
| | - Georg Dhom
- Chair of Molecular Animal Breeding and Biotechnology, LMU Munich, Munich, Germany.,Center for Innovative Medical Models, LMU Munich, Munich, Germany
| | - Wolfgang Hitzl
- Biostatistics and Data Science, Paracelsus Medical University, Salzburg, Austria
| | - Barbara Kessler
- Chair of Molecular Animal Breeding and Biotechnology, LMU Munich, Munich, Germany.,Center for Innovative Medical Models, LMU Munich, Munich, Germany
| | - Christian Eckardt
- Center for Innovative Medical Models, LMU Munich, Munich, Germany.,Large Animal Models in Cardiovascular Research, Internal Medical Department I, TU Munich, Munich, Germany
| | - Joshua Klein
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University (JGU), Mainz, Germany
| | - Anna Brymova
- Institute of Animal Physiology and Genetics, Czech Academy of Science, Libechov, Czech Republic
| | - Joshua Linnert
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University (JGU), Mainz, Germany
| | - Mayuko Kurome
- Chair of Molecular Animal Breeding and Biotechnology, LMU Munich, Munich, Germany.,Center for Innovative Medical Models, LMU Munich, Munich, Germany
| | - Valeri Zakharchenko
- Chair of Molecular Animal Breeding and Biotechnology, LMU Munich, Munich, Germany.,Center for Innovative Medical Models, LMU Munich, Munich, Germany
| | - Andrea Fischer
- Veterinary Faculty, Small Animal Clinics, LMU Munich, Munich, Germany
| | - Andreas Blutke
- Institute of Experimental Genetics, Helmholtz Center Munich, Neuherberg, Germany
| | - Anna Döring
- Veterinary Faculty, Small Animal Clinics, LMU Munich, Munich, Germany
| | - Stepanka Suchankova
- Institute of Experimental Medicine, Czech Academy of Science, Prague, Czech Republic
| | - Jiri Popelar
- Institute of Experimental Medicine, Czech Academy of Science, Prague, Czech Republic
| | - Eduardo Rodríguez-Bocanegra
- Centre for Ophthalmology, University Eye Hospital, University Hospital Tübingen, Tübingen, Germany.,Institute for Ophthalmic Research, Centre for Ophthalmology, University Hospital Tübingen, Tübingen, Germany
| | - Julia Dlugaiczyk
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich (USZ), University of Zurich, Zurich, Switzerland
| | - Hans Straka
- Faculty of Biology, LMU Munich, Planegg, Germany
| | - Helen May-Simera
- Institute of Molecular Physiology, Cilia Biology, JGU Mainz, Mainz, Germany
| | - Weiwei Wang
- Grousbeck Gene Therapy Center, Mass Eye and Ear and Harvard Medical School, Boston, MA, USA
| | - Karl-Ludwig Laugwitz
- Large Animal Models in Cardiovascular Research, Internal Medical Department I, TU Munich, Munich, Germany
| | - Luk H Vandenberghe
- Grousbeck Gene Therapy Center, Mass Eye and Ear and Harvard Medical School, Boston, MA, USA
| | - Eckhard Wolf
- Chair of Molecular Animal Breeding and Biotechnology, LMU Munich, Munich, Germany.,Center for Innovative Medical Models, LMU Munich, Munich, Germany
| | - Kerstin Nagel-Wolfrum
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University (JGU), Mainz, Germany.,Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University (JGU), Mainz, Germany
| | - Tobias Peters
- Centre for Ophthalmology, University Eye Hospital, University Hospital Tübingen, Tübingen, Germany.,Institute for Ophthalmic Research, Centre for Ophthalmology, University Hospital Tübingen, Tübingen, Germany
| | - Jan Motlik
- Institute of Animal Physiology and Genetics, Czech Academy of Science, Libechov, Czech Republic
| | - M Dominik Fischer
- Oxford Eye Hospital, Oxford University NHS Foundation Trust, Oxford, UK.,Nuffield Laboratory of Ophthalmology, NDCN, University of Oxford, Oxford, UK
| | - Uwe Wolfrum
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University (JGU), Mainz, Germany
| | - Nikolai Klymiuk
- Center for Innovative Medical Models, LMU Munich, Munich, Germany.,Large Animal Models in Cardiovascular Research, Internal Medical Department I, TU Munich, Munich, Germany
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Miles A, Blair C, Emili A, Tropepe V. Usher syndrome type 1-associated gene, pcdh15b, is required for photoreceptor structural integrity in zebrafish. Dis Model Mech 2021; 14:272551. [PMID: 34668518 PMCID: PMC8669488 DOI: 10.1242/dmm.048965] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 10/13/2021] [Indexed: 12/23/2022] Open
Abstract
Blindness associated with Usher syndrome type 1 (USH1) is typically characterized as rod photoreceptor degeneration, followed by secondary loss of cones. The mechanisms leading to blindness are unknown because most genetic mouse models only recapitulate auditory defects. We generated zebrafish mutants for one of the USH1 genes, protocadherin-15b (pcdh15b), a putative cell adhesion molecule. Zebrafish Pcdh15 is expressed exclusively in photoreceptors within calyceal processes (CPs), at the base of the outer segment (OS) and within the synapse. In our mutants, rod and cone photoreceptor integrity is compromised, with early and progressively worsening abnormal OS disc growth and detachment, in part due to weakening CP contacts. These effects were attenuated or exacerbated by growth in dark and bright-light conditions, respectively. We also describe novel evidence for structural defects in synapses of pcdh15b mutant photoreceptors. Cell death does not accompany these defects at early stages, suggesting that photoreceptor structural defects, rather than overt cell loss, may underlie vision deficits. Thus, we present the first genetic animal model of a PCDH15-associated retinopathy that can be used to understand the aetiology of blindness in USH1. This article has an associated First Person interview with the first author of the paper. Summary: We present one of the first genetic animal mutants for PCDH15 that displays a severe, early retinopathy and suggests that zebrafish could be a useful model for PCDH15-associated retinal phenotypes.
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Affiliation(s)
- Amanda Miles
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Clarke Blair
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Andrew Emili
- Center for Network Systems Biology, Boston University, Boston, MA 02118, USA
| | - Vincent Tropepe
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
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5
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Sethna S, Zein WM, Riaz S, Giese AP, Schultz JM, Duncan T, Hufnagel RB, Brewer CC, Griffith AJ, Redmond TM, Riazuddin S, Friedman TB, Ahmed ZM. Proposed therapy, developed in a Pcdh15-deficient mouse, for progressive loss of vision in human Usher syndrome. eLife 2021; 10:67361. [PMID: 34751129 PMCID: PMC8577840 DOI: 10.7554/elife.67361] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 10/20/2021] [Indexed: 12/15/2022] Open
Abstract
Usher syndrome type I (USH1) is characterized by deafness, vestibular areflexia, and progressive retinal degeneration. The protein-truncating p.Arg245* founder variant of PCDH15 (USH1F) has an ~2% carrier frequency amongst Ashkenazi Jews accounts for ~60% of their USH1 cases. Here, longitudinal phenotyping in 13 USH1F individuals revealed progressive retinal degeneration, leading to severe vision loss with macular atrophy by the sixth decade. Half of the affected individuals were legally blind by their mid-50s. The mouse Pcdh15R250X variant is equivalent to human p.Arg245*. Homozygous Pcdh15R250X mice also have visual deficits and aberrant light-dependent translocation of the phototransduction cascade proteins, arrestin, and transducin. Retinal pigment epithelium (RPE)-specific retinoid cycle proteins, RPE65 and CRALBP, were also reduced in Pcdh15R250X mice, indicating a dual role for protocadherin-15 in photoreceptors and RPE. Exogenous 9-cis retinal improved ERG amplitudes in Pcdh15R250X mice, suggesting a basis for a clinical trial of FDA-approved retinoids to preserve vision in USH1F patients.
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Affiliation(s)
- Saumil Sethna
- Department of Otorhinolaryngology - Head & Neck Surgery, University of Maryland School of Medicine, Baltimore, United States
| | - Wadih M Zein
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Sehar Riaz
- Department of Otorhinolaryngology - Head & Neck Surgery, University of Maryland School of Medicine, Baltimore, United States.,National Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Arnaud Pj Giese
- Department of Otorhinolaryngology - Head & Neck Surgery, University of Maryland School of Medicine, Baltimore, United States
| | - Julie M Schultz
- Laboratory of Molecular Genetics, National Institute of Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Todd Duncan
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Robert B Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Carmen C Brewer
- Otolaryngology Branch, National Institute of Deafness and Other Communication Disorders, Bethesda, United States
| | - Andrew J Griffith
- Otolaryngology Branch, National Institute of Deafness and Other Communication Disorders, Bethesda, United States
| | - T Michael Redmond
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Saima Riazuddin
- Department of Otorhinolaryngology - Head & Neck Surgery, University of Maryland School of Medicine, Baltimore, United States
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute of Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Zubair M Ahmed
- Department of Otorhinolaryngology - Head & Neck Surgery, University of Maryland School of Medicine, Baltimore, United States.,Departments of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, United States.,Departments of Molecular Biology and Biochemistry, University of Maryland School of Medicine, Baltimore, United States
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Sumaroka A, Cideciyan AV, Charng J, Wu V, Powers CA, Iyer BS, Lisi B, Swider M, Jacobson SG. Autosomal Dominant Retinitis Pigmentosa Due to Class B Rhodopsin Mutations: An Objective Outcome for Future Treatment Trials. Int J Mol Sci 2019; 20:ijms20215344. [PMID: 31717845 PMCID: PMC6861901 DOI: 10.3390/ijms20215344] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 10/09/2019] [Accepted: 10/16/2019] [Indexed: 12/27/2022] Open
Abstract
Gene therapy for adRP due to RHO mutations was recently shown to prevent photoreceptor death in a canine model of Class B disease. Among translational steps to be taken, one is to determine a method to detect efficacy in a human clinical trial. The relatively slow progression of adRP becomes a difficulty for clinical trials requiring an answer to whether there is slowed progression of degeneration in response to therapy. We performed a single-center, retrospective observational study of cross-sectional and longitudinal data. The study was prompted by our identification of a pericentral disease distribution in Class B RHO-adRP. Ultrawide optical coherence tomography (OCT) scans were used. Inferior retinal pericentral defects was an early disease feature. Degeneration further inferior in the retina merged with the pericentral defect, which extended into superior retina. In about 70% of patients, there was an asymmetric island of structure with significantly greater superior than inferior ellipsoid zone (EZ) extent. Serial measures of photoreceptor structure by OCT indicated constriction in superior retinal extent within a two-year interval. We conclude that these results should allow early-phase trials of therapy in RHO-adRP to move forward by inclusion of patients with an asymmetric extent of photoreceptor structure and by monitoring therapeutic effects over two years in the superior retina, a reasonable target for subretinal injection.
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7
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Kurtenbach A, Hahn G, Kernstock C, Hipp S, Zobor D, Stingl K, Kohl S, Bonnet C, Mohand-Saïd S, Sliesoraityte I, Sahel JA, Audo I, Fakin A, Hawlina M, Testa F, Simonelli F, Petit C, Zrenner E. Usher Syndrome and Color Vision. Curr Eye Res 2018; 43:1295-1301. [PMID: 30012035 DOI: 10.1080/02713683.2018.1501804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
PURPOSE The aim of this study is to report on the results of color vision testing in a European cohort of patients with Usher syndrome (USH). We describe the results in relation to Usher type (USH1 and USH2), age and visual acuity. METHODS AND METHODS The color vision of 220 genetically confirmed adult USH patients, aged 18-70 years, was analyzed with one of three methods: the Farnsworth D-15 Dichotomous test (D-15) along with the Lanthony desaturated 15 Hue tests (D-15d), the Roth 28-Hue test, or the Ishihara 14-plate test. Visual acuity was measured with either the ETDRS or the SNELLEN charts. The Confusion index, the Selectivity index and the Confusion angle were calculated for the panel tests and used for analysis. The numbers of plates that could not be read were analyzed for the Ishihara test. RESULTS For the panel tests, the degree of color loss (Confusion index) is similar in both subtypes of USH, but the polarization of error scores (Selectivity index) is significantly lower in USH1 than USH2, showing more diffuse errors than those found in USH2. There is no significant correlation between logMAR visual acuity and the Confusion or the Selectivity indices. Additionally, we find a significant correlation between patient age and the degree and the polarity of the loss only in USH2. There was no difference between USH1 and USH2 in the results of the Ishihara test. CONCLUSIONS The examination of color vision in patients with USH shows a significant difference in the pattern of color vision loss in USH1 and USH2 patients, but not in the severity of the loss. In USH2, we find a correlation between patient age and the degree and the polarity of the loss. These results may be due to differences in the pathogenesis of retinal dystrophy in USH1 and USH2.
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Affiliation(s)
- Anne Kurtenbach
- a Centre for Ophthalmology, Institute for Ophthalmic Research , University of Tuebingen , Tuebingen , Germany
| | - Gesa Hahn
- a Centre for Ophthalmology, Institute for Ophthalmic Research , University of Tuebingen , Tuebingen , Germany
| | - Christoph Kernstock
- a Centre for Ophthalmology, Institute for Ophthalmic Research , University of Tuebingen , Tuebingen , Germany
| | - Stephanie Hipp
- a Centre for Ophthalmology, Institute for Ophthalmic Research , University of Tuebingen , Tuebingen , Germany
| | - Ditta Zobor
- a Centre for Ophthalmology, Institute for Ophthalmic Research , University of Tuebingen , Tuebingen , Germany
| | - Katarina Stingl
- a Centre for Ophthalmology, Institute for Ophthalmic Research , University of Tuebingen , Tuebingen , Germany
| | - Susanne Kohl
- a Centre for Ophthalmology, Institute for Ophthalmic Research , University of Tuebingen , Tuebingen , Germany
| | - Crystel Bonnet
- b Institut de la Vision , INSERM UMRS 1120 , Paris , France.,c Complexité du vivant , UPMC-Sorbonnes Universités , Paris , France
| | - Saddek Mohand-Saïd
- b Institut de la Vision , INSERM UMRS 1120 , Paris , France.,d Centre d'Investigation Clinique, Direction de l'Hospitalisation et de l'Organisation des Soins , Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts , Paris , France
| | | | - José-Alain Sahel
- b Institut de la Vision , INSERM UMRS 1120 , Paris , France.,c Complexité du vivant , UPMC-Sorbonnes Universités , Paris , France.,d Centre d'Investigation Clinique, Direction de l'Hospitalisation et de l'Organisation des Soins , Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts , Paris , France
| | - Isabelle Audo
- b Institut de la Vision , INSERM UMRS 1120 , Paris , France.,d Centre d'Investigation Clinique, Direction de l'Hospitalisation et de l'Organisation des Soins , Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts , Paris , France
| | - Ana Fakin
- f Eye Hospital , University Medical Centre Ljubljana , Ljubljana , Slovenia
| | - Marko Hawlina
- f Eye Hospital , University Medical Centre Ljubljana , Ljubljana , Slovenia
| | - Francesco Testa
- g Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences , University of Campania Luigi Vanvitelli , Naples , Italy
| | - Francesca Simonelli
- g Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences , University of Campania Luigi Vanvitelli , Naples , Italy
| | - Christine Petit
- b Institut de la Vision , INSERM UMRS 1120 , Paris , France.,c Complexité du vivant , UPMC-Sorbonnes Universités , Paris , France.,h , Collège de France , Paris , France.,i Génétique et Physiologie de l`Audition , Institut Pasteur , Paris , France
| | - Eberhart Zrenner
- a Centre for Ophthalmology, Institute for Ophthalmic Research , University of Tuebingen , Tuebingen , Germany.,j Werner Reichardt Centre for Integrative Neuroscience (CIN) , University of Tübingen , Tübingen , Germany
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8
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Cone degeneration is triggered by the absence of USH1 proteins but prevented by antioxidant treatments. Sci Rep 2018; 8:1968. [PMID: 29386551 PMCID: PMC5792440 DOI: 10.1038/s41598-018-20171-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/04/2018] [Indexed: 11/26/2022] Open
Abstract
Usher syndrome type 1 (USH1) is a major cause of inherited deafness and blindness in humans. The eye disorder is often referred to as retinitis pigmentosa, which is characterized by a secondary cone degeneration following the rod loss. The development of treatments to prevent retinal degeneration has been hampered by the lack of clear evidence for retinal degeneration in mutant mice deficient for the Ush1 genes, which instead faithfully mimic the hearing deficit. We show that, under normal housing conditions, Ush1g−/− and Ush1c−/− albino mice have dysfunctional cone photoreceptors whereas pigmented knockout animals have normal photoreceptors. The key involvement of oxidative stress in photoreceptor apoptosis and the ensued retinal gliosis were further confirmed by their prevention when the mutant mice are reared under darkness and/or supplemented with antioxidants. The primary degeneration of cone photoreceptors contrasts with the typical forms of retinitis pigmentosa. Altogether, we propose that oxidative stress probably accounts for the high clinical heterogeneity among USH1 siblings, which also unveils potential targets for blindness prevention.
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Matsui R, Cideciyan AV, Schwartz SB, Sumaroka A, Roman AJ, Swider M, Huang WC, Sheplock R, Jacobson SG. Molecular Heterogeneity Within the Clinical Diagnosis of Pericentral Retinal Degeneration. Invest Ophthalmol Vis Sci 2016; 56:6007-18. [PMID: 26393467 DOI: 10.1167/iovs.15-17174] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize in detail the phenotype and genotype of patients with pericentral retinal degeneration (PRD). METHODS Patients were screened for an annular ring scotoma ranging from 3° to 40° (n = 28, ages 24-71) with kinetic perimetry. All patients had pigmentary retinopathy in the region of the dysfunction. Further studies included cross-sectional and en face imaging, static chromatic perimetry, and electroretinography. Molecular screening was performed. RESULTS Genotypes of 14 of 28 PRD patients were identified: There were mutations in eight different genes previously associated with autosomal dominant or autosomal recessive RDs. Kinetic fields monitored in some patients over years to more than a decade could be stable or show increased extent of the scotoma. Electroretinograms were recordable but with different severities of dysfunction. Patterns of photoreceptor outer nuclear layer (ONL) loss corresponded to the distribution of visual dysfunction. Outer nuclear layer thickness topography and en face imaging indicated that the greatest disease expression was in the area of known highest rod photoreceptor density. CONCLUSIONS Molecular heterogeneity was a feature of the PRD phenotype. Many of the molecular causes were also associated with other phenotypes, such as maculopathies, typical retinitis pigmentosa (RP) and cone-rod dystrophy. The pericentral pattern of retinal degeneration is thus confirmed to be an uncommon phenotype of many different genotypes rather than a distinct disease entity.
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Toms M, Bitner-Glindzicz M, Webster A, Moosajee M. Usher syndrome: a review of the clinical phenotype, genes and therapeutic strategies. EXPERT REVIEW OF OPHTHALMOLOGY 2015. [DOI: 10.1586/17469899.2015.1033403] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Mathur P, Yang J. Usher syndrome: Hearing loss, retinal degeneration and associated abnormalities. Biochim Biophys Acta Mol Basis Dis 2014; 1852:406-20. [PMID: 25481835 DOI: 10.1016/j.bbadis.2014.11.020] [Citation(s) in RCA: 220] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 11/25/2014] [Accepted: 11/26/2014] [Indexed: 02/06/2023]
Abstract
Usher syndrome (USH), clinically and genetically heterogeneous, is the leading genetic cause of combined hearing and vision loss. USH is classified into three types, based on the hearing and vestibular symptoms observed in patients. Sixteen loci have been reported to be involved in the occurrence of USH and atypical USH. Among them, twelve have been identified as causative genes and one as a modifier gene. Studies on the proteins encoded by these USH genes suggest that USH proteins interact among one another and function in multiprotein complexes in vivo. Although their exact functions remain enigmatic in the retina, USH proteins are required for the development, maintenance and function of hair bundles, which are the primary mechanosensitive structure of inner ear hair cells. Despite the unavailability of a cure, progress has been made to develop effective treatments for this disease. In this review, we focus on the most recent discoveries in the field with an emphasis on USH genes, protein complexes and functions in various tissues as well as progress toward therapeutic development for USH.
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Affiliation(s)
- Pranav Mathur
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA; Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84132, USA
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA; Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84132, USA; Department of Otolaryngology Head and Neck Surgery, University of Utah, Salt Lake City, UT 84132, USA.
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12
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Zein WM, Falsini B, Tsilou ET, Turriff AE, Schultz JM, Friedman TB, Brewer CC, Zalewski CK, King KA, Muskett JA, Rehman AU, Morell RJ, Griffith AJ, Sieving PA. Cone responses in Usher syndrome types 1 and 2 by microvolt electroretinography. Invest Ophthalmol Vis Sci 2014; 56:107-14. [PMID: 25425308 DOI: 10.1167/iovs.14-15355] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Progressive decline of psychophysical cone-mediated measures has been reported in type 1 (USH1) and type 2 (USH2) Usher syndrome. Conventional cone electroretinogram (ERG) responses in USH demonstrate poor signal-to-noise ratio. We evaluated cone signals in USH1 and USH2 by recording microvolt level cycle-by-cycle (CxC) ERG. METHODS Responses of molecularly genotyped USH1 (n = 18) and USH2 (n = 24) subjects (age range, 15-69 years) were compared with those of controls (n = 12). A subset of USH1 (n = 9) and USH2 (n = 9) subjects was examined two to four times over 2 to 8 years. Photopic CxC ERG and conventional 30-Hz flicker ERG were recorded on the same visits. RESULTS Usher syndrome subjects showed considerable cone flicker ERG amplitude losses and timing phase delays (P < 0.01) compared with controls. USH1 and USH2 had similar rates of progressive logarithmic ERG amplitude decline with disease duration (-0.012 log μV/y). Of interest, ERG phase delays did not progress over time. Two USH1C subjects retained normal response timing despite reduced amplitudes. The CxC ERG method provided reliable responses in all subjects, whereas conventional ERG was undetectable in 7 of 42 subjects. CONCLUSIONS Cycle-by-cycle ERG showed progressive loss of amplitude in both USH1 and USH2 subjects, comparable to that reported with psychophysical measures. Usher subjects showed abnormal ERG response latency, but this changed less than amplitude with time. In USH syndrome, CxC ERG is more sensitive than conventional ERG and warrants consideration as an outcome measure in USH treatment trials.
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Affiliation(s)
- Wadih M Zein
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Benedetto Falsini
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Ekaterina T Tsilou
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Amy E Turriff
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Julie M Schultz
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Carmen C Brewer
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Christopher K Zalewski
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Kelly A King
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Julie A Muskett
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Atteeq U Rehman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Robert J Morell
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Andrew J Griffith
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Paul A Sieving
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
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The retinal phenotype of Usher syndrome: pathophysiological insights from animal models. C R Biol 2014; 337:167-77. [PMID: 24702843 DOI: 10.1016/j.crvi.2013.12.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 12/03/2013] [Indexed: 01/26/2023]
Abstract
The Usher syndrome (USH) is the most prevalent cause of inherited deaf-blindness. Three clinical subtypes, USH1-3, have been defined, and ten USH genes identified. The hearing impairment due to USH gene defects has been shown to result from improper organisation of the hair bundle, the sound receptive structure of sensory hair cells. In contrast, the cellular basis of the visual defect is less well understood as this phenotype is absent in almost all the USH mouse models that faithfully mimic the human hearing impairment. Structural and molecular interspecies discrepancies regarding photoreceptor calyceal processes and the association with the distribution of USH1 proteins have recently been unravelled, and have led to the conclusion that a defect in the USH1 protein complex-mediated connection between the photoreceptor outer segment and the surrounding calyceal processes (in both rods and cones), and the inner segment (in rods only), probably causes the USH1 retinal dystrophy in humans.
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Abstract
The 10 different genes associated with the deaf/blind disorder, Usher syndrome, encode a number of structurally and functionally distinct proteins, most expressed as multiple isoforms/protein variants. Functional characterization of these proteins suggests a role in stereocilia development in cochlear hair cells, likely owing to adhesive interactions in hair bundles. In mature hair cells, homodimers of the Usher cadherins, cadherin 23 and protocadherin 15, interact to form a structural fiber, the tip link, and the linkages that anchor the taller stereocilia's actin cytoskeleton core to the shorter adjacent stereocilia and the elusive mechanotransduction channels, explaining the deafness phenotype when these molecular interactions are perturbed. The conundrum is that photoreceptors lack a synonymous mechanotransduction apparatus, and so a common theory for Usher protein function in the two neurosensory cell types affected in Usher syndrome is lacking. Recent evidence linking photoreceptor cell dysfunction in the shaker 1 mouse model for Usher syndrome to light-induced protein translocation defects, combined with localization of an Usher protein interactome at the periciliary region of the photoreceptors suggests Usher proteins might regulate protein trafficking between the inner and outer segments of photoreceptors. A distinct Usher protein complex is trafficked to the ribbon synapses of hair cells, and synaptic defects have been reported in Usher mutants in both hair cells and photoreceptors. This review aims to clarify what is known about Usher protein function at the synaptic and apical poles of hair cells and photoreceptors and the prospects for identifying a unifying pathobiological mechanism to explain deaf/blindness in Usher syndrome.
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Papal S, Cortese M, Legendre K, Sorusch N, Dragavon J, Sahly I, Shorte S, Wolfrum U, Petit C, El-Amraoui A. The giant spectrin βV couples the molecular motors to phototransduction and Usher syndrome type I proteins along their trafficking route. Hum Mol Genet 2013; 22:3773-88. [PMID: 23704327 DOI: 10.1093/hmg/ddt228] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutations in the myosin VIIa gene cause Usher syndrome type IB (USH1B), characterized by deaf-blindness. A delay of opsin trafficking has been observed in the retinal photoreceptor cells of myosin VIIa-deficient mice. We identified spectrin βV, the mammalian β-heavy spectrin, as a myosin VIIa- and rhodopsin-interacting partner in photoreceptor cells. Spectrin βV displays a polarized distribution from the Golgi apparatus to the base of the outer segment, which, unlike that of other β spectrins, matches the trafficking route of opsin and other phototransduction proteins. Formation of spectrin βV-rhodopsin complex could be detected in the differentiating photoreceptors as soon as their outer segment emerges. A failure of the spectrin βV-mediated coupling between myosin VIIa and opsin molecules thus probably accounts for the opsin transport delay in myosin VIIa-deficient mice. We showed that spectrin βV also associates with two USH1 proteins, sans (USH1G) and harmonin (USH1C). Spectrins are supposed to function as heteromers of α and β subunits, but fluorescence resonance energy transfer and in vitro binding experiments indicated that spectrin βV can also form homodimers, which likely supports its αII-independent βV functions. Finally, consistent with its distribution along the connecting cilia axonemes, spectrin βV binds to several subunits of the microtubule-based motor proteins, kinesin II and the dynein complex. We therefore suggest that spectrin βV homomers couple some USH1 proteins, opsin and other phototransduction proteins to both actin- and microtubule-based motors, thereby contributing to their transport towards the photoreceptor outer disks.
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Affiliation(s)
- Samantha Papal
- Institut Pasteur, Unité de génétique et physiologie de l'audition, Paris, France
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Sahly I, Dufour E, Schietroma C, Michel V, Bahloul A, Perfettini I, Pepermans E, Estivalet A, Carette D, Aghaie A, Ebermann I, Lelli A, Iribarne M, Hardelin JP, Weil D, Sahel JA, El-Amraoui A, Petit C. Localization of Usher 1 proteins to the photoreceptor calyceal processes, which are absent from mice. ACTA ACUST UNITED AC 2012; 199:381-99. [PMID: 23045546 PMCID: PMC3471240 DOI: 10.1083/jcb.201202012] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanisms underlying retinal dystrophy in Usher syndrome type I (USH1) remain unknown because mutant mice lacking any of the USH1 proteins-myosin VIIa, harmonin, cadherin-23, protocadherin-15, sans-do not display retinal degeneration. We found here that, in macaque photoreceptor cells, all USH1 proteins colocalized at membrane interfaces (i) between the inner and outer segments in rods and (ii) between the microvillus-like calyceal processes and the outer segment basolateral region in rods and cones. This pattern, conserved in humans and frogs, was mediated by the formation of an USH1 protein network, which was associated with the calyceal processes from the early embryonic stages of outer segment growth onwards. By contrast, mouse photoreceptors lacked calyceal processes and had no USH1 proteins at the inner-outer segment interface. We suggest that USH1 proteins form an adhesion belt around the basolateral region of the photoreceptor outer segment in humans, and that defects in this structure cause the retinal degeneration in USH1 patients.
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Affiliation(s)
- Iman Sahly
- Institut de la vision, Syndrome de Usher et autres Atteintes Rétino-Cochléaires, 75012 Paris, France
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The dynamic architecture of photoreceptor ribbon synapses: cytoskeletal, extracellular matrix, and intramembrane proteins. Vis Neurosci 2012; 28:453-71. [PMID: 22192503 DOI: 10.1017/s0952523811000356] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Rod and cone photoreceptors possess ribbon synapses that assist in the transmission of graded light responses to second-order bipolar and horizontal cells of the vertebrate retina. Proper functioning of the synapse requires the juxtaposition of presynaptic release sites immediately adjacent to postsynaptic receptors. In this review, we focus on the synaptic, cytoskeletal, and extracellular matrix proteins that help to organize photoreceptor ribbon synapses in the outer plexiform layer. We examine the proteins that foster the clustering of release proteins, calcium channels, and synaptic vesicles in the presynaptic terminals of photoreceptors adjacent to their postsynaptic contacts. Although many proteins interact with one another in the presynaptic terminal and synaptic cleft, these protein-protein interactions do not create a static and immutable structure. Instead, photoreceptor ribbon synapses are remarkably dynamic, exhibiting structural changes on both rapid and slow time scales.
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Abstract
PURPOSE To determine the molecular cause of sector retinitis pigmentosa and hearing loss in two affected siblings. METHODS Direct DNA sequencing of the USH1C gene was performed in two affected siblings. Putative pathogenic sequence changes were assayed in their parent's chromosomes and in control chromosomes. Clinical examination included visual acuity measurement, visual field measurement, electrophysiologic assessment, and fine matrix mapping. Retinal imaging with fundus photography, scanning laser ophthalmoscope (fundus autofluorescence), and optical coherence tomography was performed. Hearing and vestibular function was also assessed. RESULTS The siblings were aged 42 years and 40 years, and both were compound heterozygotes for the p.R103H missense change and the novel splice site change c.2227-1G>A in the USH1C gene. Both alleles were found to be in trans. Neither allele was identified in a panel of 866 control chromosomes, and both were considered pathogenic. Both siblings had sector retinitis pigmentosa restricted to the inferior and nasal retina. Fundus autofluorescence imaging showed a clear demarcation between normal and abnormal areas of retina, which corresponded to areas of reduced sensitivity on fine matrix mapping and loss of visual field. Both siblings had severe hearing loss but were able to develop language. CONCLUSION We report a novel molecular cause of sector retinitis pigmentosa associated with hearing loss representing a new phenotype associated with mutations in the USH1C gene.
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Shu X, Luhmann UFO, Aleman TS, Barker SE, Lennon A, Tulloch B, Chen M, Xu H, Jacobson SG, Ali R, Wright AF. Characterisation of a C1qtnf5 Ser163Arg knock-in mouse model of late-onset retinal macular degeneration. PLoS One 2011; 6:e27433. [PMID: 22110650 PMCID: PMC3217991 DOI: 10.1371/journal.pone.0027433] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 10/17/2011] [Indexed: 11/19/2022] Open
Abstract
A single founder mutation resulting in a Ser163Arg substitution in the C1QTNF5 gene product causes autosomal dominant late-onset retinal macular degeneration (L-ORMD) in humans, which has clinical and pathological features resembling age-related macular degeneration. We generated and characterised a mouse “knock-in” model carrying the Ser163Arg mutation in the orthologous murine C1qtnf5 gene by site-directed mutagenesis and homologous recombination into mouse embryonic stem cells. Biochemical, immunological, electron microscopic, fundus autofluorescence, electroretinography and laser photocoagulation analyses were used to characterise the mouse model. Heterozygous and homozygous knock-in mice showed no significant abnormality in any of the above measures at time points up to 2 years. This result contrasts with another C1qtnf5 Ser163Arg knock-in mouse which showed most of the features of L-ORMD but differed in genetic background and targeting construct.
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Affiliation(s)
- Xinhua Shu
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, Edinburgh, United Kingdom
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
- Department of Vision Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
| | | | - Tomas S. Aleman
- Scheie Eye Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | | | - Alan Lennon
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, Edinburgh, United Kingdom
| | - Brian Tulloch
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, Edinburgh, United Kingdom
| | - Mei Chen
- Centre for Vision and Vascular Science, Queen's University Belfast, Belfast, United Kingdom
| | - Heping Xu
- Centre for Vision and Vascular Science, Queen's University Belfast, Belfast, United Kingdom
| | - Samuel G. Jacobson
- Scheie Eye Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Robin Ali
- UCL Institute of Ophthalmology, London, United Kingdom
| | - Alan F. Wright
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, Edinburgh, United Kingdom
- * E-mail:
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Jacobson SG, Cideciyan AV, Gibbs D, Sumaroka A, Roman AJ, Aleman TS, Schwartz SB, Olivares MB, Russell RC, Steinberg JD, Kenna MA, Kimberling WJ, Rehm HL, Williams DS. Retinal disease course in Usher syndrome 1B due to MYO7A mutations. Invest Ophthalmol Vis Sci 2011; 52:7924-36. [PMID: 21873662 DOI: 10.1167/iovs.11-8313] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PURPOSE. To determine the disease course in Usher syndrome type IB (USH1B) caused by myosin 7A (MYO7A) gene mutations. METHODS. USH1B patients (n = 33, ages 2-61) representing 25 different families were studied by ocular examination, kinetic and chromatic static perimetry, dark adaptometry, and optical coherence tomography (OCT). Consequences of the mutant alleles were predicted. RESULTS. All MYO7A patients had severely abnormal ERGs, but kinetic fields revealed regional patterns of visual loss that suggested a disease sequence. Rod-mediated vision could be lost to different degrees in the first decades of life. Cone vision followed a more predictable and slower decline. Central vision ranged from normal to reduced in the first four decades of life and thereafter was severely abnormal. Dark adaptation kinetics was normal. Photoreceptor layer thickness in a wide region of central retina could differ dramatically between patients of comparable ages; and there were examples of severe losses in childhood as well as relative preservation in patients in the third decade of life. Comparisons were made between the mutant alleles in mild versus more severe phenotypes. CONCLUSIONS. A disease sequence in USH1B leads from generally full but impaired visual fields to residual small central islands. At most disease stages, there was preserved temporal peripheral field, a potential target for early phase clinical trials of gene therapy. From data comparing patients' rod disease in this cohort, the authors speculate that null MYO7A alleles could be associated with milder dysfunction and fewer photoreceptor structural losses at ages when other genotypes show more severe phenotypes.
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Affiliation(s)
- Samuel G Jacobson
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, USA.
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Murillo-Cuesta S, Rodríguez-de la Rosa L, Cediel R, Lassaletta L, Varela-Nieto I. The role of insulin-like growth factor-I in the physiopathology of hearing. Front Mol Neurosci 2011; 4:11. [PMID: 21845174 PMCID: PMC3146045 DOI: 10.3389/fnmol.2011.00011] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 07/11/2011] [Indexed: 01/19/2023] Open
Abstract
Insulin-like growth factor-I (IGF-I) belongs to the family of polypeptides of insulin, which play a central role in embryonic development and adult nervous system homeostasis by endocrine, autocrine, and paracrine mechanisms. IGF-I is fundamental for the regulation of cochlear development, growth, and differentiation, and its mutations are associated with hearing loss in mice and men. Low levels of IGF-I have been shown to correlate with different human syndromes showing hearing loss and with presbyacusis. Animal models are fundamental to understand the genetic, epigenetic, and environmental factors that contribute to human hearing loss. In the mouse, IGF-I serum levels decrease with aging and there is a concomitant hearing loss and retinal degeneration. In the Igf1(-/-) null mouse, hearing loss is due to neuronal loss, poor innervation of the sensory hair cells, and age-related stria vascularis alterations. In the inner ear, IGF-I actions are mediated by intracellular signaling networks, RAF, AKT, and p38 MAPK protein kinases modulate the expression and activity of transcription factors, as AP1, MEF2, FoxM1, and FoxP3, leading to the regulation of cell cycle and metabolism. Therapy with rhIGF-I has been approved in humans for the treatment of poor linear growth and certain neurodegenerative diseases. This review will discuss these findings and their implications in new IGF-I-based treatments for the protection or repair of hearing loss.
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Affiliation(s)
- Silvia Murillo-Cuesta
- Servicio de Evaluación Neurofuncional no Invasiva, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid Madrid, Spain
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Phillips JB, Blanco-Sanchez B, Lentz JJ, Tallafuss A, Khanobdee K, Sampath S, Jacobs ZG, Han PF, Mishra M, Titus TA, Williams DS, Keats BJ, Washbourne P, Westerfield M. Harmonin (Ush1c) is required in zebrafish Müller glial cells for photoreceptor synaptic development and function. Dis Model Mech 2011; 4:786-800. [PMID: 21757509 PMCID: PMC3209648 DOI: 10.1242/dmm.006429] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Usher syndrome is the most prevalent cause of hereditary deaf-blindness, characterized by congenital sensorineural hearing impairment and progressive photoreceptor degeneration beginning in childhood or adolescence. Diagnosis and management of this disease are complex, and the molecular changes underlying sensory cell impairment remain poorly understood. Here we characterize two zebrafish models for a severe form of Usher syndrome, Usher syndrome type 1C (USH1C): one model is a mutant with a newly identified ush1c nonsense mutation, and the other is a morpholino knockdown of ush1c. Both have defects in hearing, balance and visual function from the first week of life. Histological analyses reveal specific defects in sensory cell structure that are consistent with these behavioral phenotypes and could implicate Müller glia in the retinal pathology of Usher syndrome. This study shows that visual defects associated with loss of ush1c function in zebrafish can be detected from the onset of vision, and thus could be applicable to early diagnosis for USH1C patients.
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Bramall AN, Wright AF, Jacobson SG, McInnes RR. The genomic, biochemical, and cellular responses of the retina in inherited photoreceptor degenerations and prospects for the treatment of these disorders. Annu Rev Neurosci 2011; 33:441-72. [PMID: 20572772 DOI: 10.1146/annurev-neuro-060909-153227] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The association of more than 140 genes with human photoreceptor degenerations, together with studies of animal models of these monogenic diseases, has provided great insight into their pathogenesis. Here we review the responses of the retina to photoreceptor mutations, including mechanisms of photoreceptor death. We discuss the roles of oxidative metabolism, mitochondrial reactive oxygen species, metabolic stress, protein misfolding, and defects in ciliary proteins, as well as the responses of Müller glia, microglia, and the retinal vasculature. Finally, we report on potential pharmacologic and biologic therapies, the critical role of histopathology as a prerequisite to treatment, and the exciting promise of gene therapy in animal models and in phase 1 trials in humans.
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Affiliation(s)
- Alexa N Bramall
- Programs in Genetics and Developmental Biology, The Research Institute, The Hospital for Sick Children, Toronto M5G1L7, Canada.
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Yetemian RM, Brown BM, Craft CM. Neovascularization, enhanced inflammatory response, and age-related cone dystrophy in the Nrl-/-Grk1-/- mouse retina. Invest Ophthalmol Vis Sci 2010; 51:6196-206. [PMID: 20688726 DOI: 10.1167/iovs.10-5452] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The effects of aging and light exposure on cone photoreceptor survival were compared between mouse retinas of neural retina leucine zipper knockout (Nrl(-/-)) mice and double-knockout mice lacking G-protein-coupled receptor kinase 1 (Nrl(-/-)Grk1(-/-)). METHODS Mice were reared in total darkness, ambient cyclic light, or constant light, and their retinas were evaluated from 1 to 9 months of age using immunohistochemistry, electroretinography, and fluorescein angiography. Retinal gene expression and statistically significant probe sets were categorized using analysis software. Select gene expression changes were confirmed with quantitative RT-PCR. RESULTS In contrast to retinas from Nrl(-/-), those from Nrl(-/-)Grk1(-/-) exhibit a progressive loss of the outer nuclear layer, retinal physiology deficits, and a higher rate of degeneration with increasing age that is independent of environmental light exposure. Changes in retinal neovascularization occur in the Nrl(-/-)Grk1(-/-) at 1 month, before the onset of significant cone functional deficits. Microarray analyses demonstrate statistically significant changes in transcript levels of more than 400 genes, of which the oncostatin M signaling pathway and the inflammatory disease response network were identified. CONCLUSIONS These data demonstrate that the loss of functional Grk1 on the enhanced S-cone Nrl(-/-) background exacerbates age-related cone dystrophy in a light-independent manner, mediated partly through the inflammatory response pathway and neovascularization. According to these findings, Grk1 helps to maintain a healthy cone environment, and the Nrl(-/-)Grk1(-/-) mouse allows examination of the alternative roles of Grk1 in cone photoreceptor homeostasis.
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Affiliation(s)
- Rosanne M Yetemian
- Doheny Eye Institute, Department of Ophthalmology, Division of Retinal Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033-9224, USA
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Lentz JJ, Gordon WC, Farris HE, MacDonald GH, Cunningham DE, Robbins CA, Tempel BL, Bazan NG, Rubel EW, Oesterle EC, Keats BJ. Deafness and retinal degeneration in a novel USH1C knock-in mouse model. Dev Neurobiol 2010; 70:253-67. [PMID: 20095043 DOI: 10.1002/dneu.20771] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Usher syndrome is the leading cause of combined deaf-blindness, but the molecular mechanisms underlying the auditory and visual impairment are poorly understood. Usher I is characterized by profound congenital hearing loss, vestibular dysfunction, and progressive retinitis pigmentosa beginning in early adolescence. Using the c.216G>A cryptic splice site mutation in Exon 3 of the USH1C gene found in Acadian Usher I patients in Louisiana, we constructed the first mouse model that develops both deafness and retinal degeneration. The same truncated mRNA transcript found in Usher 1C patients is found in the cochleae and retinas of these knock-in mice. Absent auditory-evoked brainstem responses indicated that the mutant mice are deaf at 1 month of age. Cochlear histology showed disorganized hair cell rows, abnormal bundles, and loss of both inner and outer hair cells in the middle turns and at the base. Retinal dysfunction as evident by an abnormal electroretinogram was seen as early as 1 month of age, with progressive loss of rod photoreceptors between 6 and 12 months of age. This knock-in mouse reproduces the dual sensory loss of human Usher I, providing a novel resource to study the disease mechanism and the development of therapies.
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Affiliation(s)
- Jennifer J Lentz
- Department of Genetics, LSU Health Sciences Center, New Orleans, Louisiana, USA.
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Gómez Ravetti M, Rosso OA, Berretta R, Moscato P. Uncovering molecular biomarkers that correlate cognitive decline with the changes of hippocampus' gene expression profiles in Alzheimer's disease. PLoS One 2010; 5:e10153. [PMID: 20405009 PMCID: PMC2854141 DOI: 10.1371/journal.pone.0010153] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 03/22/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is characterized by a neurodegenerative progression that alters cognition. On a phenotypical level, cognition is evaluated by means of the MiniMental State Examination (MMSE) and the post-mortem examination of Neurofibrillary Tangle count (NFT) helps to confirm an AD diagnostic. The MMSE evaluates different aspects of cognition including orientation, short-term memory (retention and recall), attention and language. As there is a normal cognitive decline with aging, and death is the final state on which NFT can be counted, the identification of brain gene expression biomarkers from these phenotypical measures has been elusive. METHODOLOGY/PRINCIPAL FINDINGS We have reanalysed a microarray dataset contributed in 2004 by Blalock et al. of 31 samples corresponding to hippocampus gene expression from 22 AD subjects of varying degree of severity and 9 controls. Instead of only relying on correlations of gene expression with the associated MMSE and NFT measures, and by using modern bioinformatics methods based on information theory and combinatorial optimization, we uncovered a 1,372-probe gene expression signature that presents a high-consensus with established markers of progression in AD. The signature reveals alterations in calcium, insulin, phosphatidylinositol and wnt-signalling. Among the most correlated gene probes with AD severity we found those linked to synaptic function, neurofilament bundle assembly and neuronal plasticity. CONCLUSIONS/SIGNIFICANCE A transcription factors analysis of 1,372-probe signature reveals significant associations with the EGR/KROX family of proteins, MAZ, and E2F1. The gene homologous of EGR1, zif268, Egr-1 or Zenk, together with other members of the EGR family, are consolidating a key role in the neuronal plasticity in the brain. These results indicate a degree of commonality between putative genes involved in AD and prion-induced neurodegenerative processes that warrants further investigation.
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Affiliation(s)
- Martín Gómez Ravetti
- Centre for Bioinformatics, Biomarker Discovery and Information-Based Medicine, The University of Newcastle, Callaghan, New South Wales, Australia
- Hunter Medical Research Institute, Information Based Medicine Program, John Hunter Hospital, New Lambton Heights, New South Wales, Australia
- Australian Research Council Centre of Excellence in Bioinformatics, Callaghan, New South Wales, Australia
| | - Osvaldo A. Rosso
- Centre for Bioinformatics, Biomarker Discovery and Information-Based Medicine, The University of Newcastle, Callaghan, New South Wales, Australia
- Hunter Medical Research Institute, Information Based Medicine Program, John Hunter Hospital, New Lambton Heights, New South Wales, Australia
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Regina Berretta
- Centre for Bioinformatics, Biomarker Discovery and Information-Based Medicine, The University of Newcastle, Callaghan, New South Wales, Australia
- Hunter Medical Research Institute, Information Based Medicine Program, John Hunter Hospital, New Lambton Heights, New South Wales, Australia
| | - Pablo Moscato
- Centre for Bioinformatics, Biomarker Discovery and Information-Based Medicine, The University of Newcastle, Callaghan, New South Wales, Australia
- Hunter Medical Research Institute, Information Based Medicine Program, John Hunter Hospital, New Lambton Heights, New South Wales, Australia
- Australian Research Council Centre of Excellence in Bioinformatics, Callaghan, New South Wales, Australia
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Tian C, Liu XZ, Han F, Yu H, Longo-Guess C, Yang B, Lu C, Yan D, Zheng QY. Ush1c gene expression levels in the ear and eye suggest different roles for Ush1c in neurosensory organs in a new Ush1c knockout mouse. Brain Res 2010; 1328:57-70. [PMID: 20211154 DOI: 10.1016/j.brainres.2010.02.079] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 01/15/2010] [Accepted: 02/26/2010] [Indexed: 02/03/2023]
Abstract
Usher syndrome (USH) is the most common form of deaf-blindness in humans. Molecular characterization revealed that the USH gene products form a macromolecular protein network in hair cells of the inner ear and in photoreceptor cells of the retina via binding to PDZ domains in the scaffold protein harmonin encoded by the Ush1c gene in mice and humans. Although several mouse mutants for the Ush1c gene have been described, we generated a targeted null mutation Ush1c mouse model in which the first four exons of the Ush1c gene were replaced with a reporter gene. Here, we assessed the expression pattern of the reporter gene under control of Ush1c regulatory elements and characterized the phenotype of mice defective for Ush1c. These Ush1 knockout mice are deaf but do not recapitulate vision defects before 10 months of age. Our data show LacZ expression in multiple layers of the retina but in neither outer nor inner segments of the photoreceptor layers in mice bearing the knockout construct at 1-5 months of age. The fact that Ush1c expression is much higher in the ear than in the eye suggests a different role for Ush1c in ear function than in the eye and may explain why Ush1c mutant mice do not recapitulate vision defects.
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Affiliation(s)
- Cong Tian
- Department of Otolaryngology, Case Western Reserve University, Cleveland, OH 44106, USA
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Lagziel A, Overlack N, Bernstein SL, Morell RJ, Wolfrum U, Friedman TB. Expression of cadherin 23 isoforms is not conserved: implications for a mouse model of Usher syndrome type 1D. Mol Vis 2009; 15:1843-57. [PMID: 19756182 PMCID: PMC2743805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Accepted: 09/03/2009] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We compared cadherin 23 (Cdh23) mRNA and protein variants in the inner ear and retina of wild-type and mutant mice and primates to better understand the pleiotropic effects of Cdh23 mutations, and specifically to understand the absence of retinal degeneration in Cdh23 mutant mice. METHODS Semiquantitative real-time PCR was used to compare the level of expression of Cdh23 alternative transcripts in the inner ear and retina of wild-type and homozygous Cdh23(v-6J) (waltzer) mice. Antibodies generated against CDH23 isoforms were used in immunohistochemistry, immunohistology, electron microscopy, and western blot analyses of mouse and primate inner ear and retina to study the distribution of these isoforms in various cellular compartments. RESULTS Cdh23 mRNA alternative splice variants were temporally and spatially regulated in the inner ear and retina. In the mature mouse retina, CDH23 isoforms were broadly expressed in various cellular compartments of the photoreceptor layer. The wild-type CDH23_V3 protein isoform, which has PDZ binding motifs but neither extracellular domains nor a transmembrane domain, localized exclusively to the outer plexiform layer of the retina containing photoreceptor cell synapses and to the synaptic region of auditory and vestibular hair cells. The longest CDH23 protein isoform, CDH23_V1, appeared by western blotting to be the only one affected by the Cdh23(v-6J) mutation; it was expressed in the wild-type mouse inner ear, but not in the mouse retina. However, CDH23_V1 was detected in western blot analyses of monkey and human retinas. CONCLUSIONS The time- and tissue-dependent expression patterns that we have shown for Cdh23 alternative transcripts suggest developmental roles and tissue-specific functions for the various transcripts. Many of these isoforms continue to be expressed in waltzer mice. The longest CDH23 isoform (CDH23_V1), however, is not expressed in mutant mice and is necessary for normal inner ear function. The longest isoform is expressed in the retinas of primates, but not detected in the mouse retina. This species difference suggests that the mouse may not be a suitable model for studying the retinitis pigmentosa phenotype of human Usher syndrome type 1D.
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Affiliation(s)
- Ayala Lagziel
- Section on Human Genetics, Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD
| | - Nora Overlack
- Johannes Gutenberg-University, Institute of Zoology, Department of Cell and Matrix Biology, Mainz, Germany
| | - Steven L. Bernstein
- Department of Ophthalmology, University of Maryland School of Medicine, Baltimore, MD
| | - Robert J. Morell
- Section on Human Genetics, Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD
| | - Uwe Wolfrum
- Johannes Gutenberg-University, Institute of Zoology, Department of Cell and Matrix Biology, Mainz, Germany
| | - Thomas B. Friedman
- Section on Human Genetics, Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD
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Gibbs D, Diemer T, Khanobdee K, Hu J, Bok D, Williams DS. Function of MYO7A in the human RPE and the validity of shaker1 mice as a model for Usher syndrome 1B. Invest Ophthalmol Vis Sci 2009; 51:1130-5. [PMID: 19643958 DOI: 10.1167/iovs.09-4032] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the function of MYO7A in human RPE cells and to test the validity of using shaker1 RPE in preclinical studies on therapies for Usher syndrome 1B by comparing human and mouse cells. METHODS MYO7A was localized by immunofluorescence. Primary cultures of human and mouse RPE cells were used to measure melanosome motility and rod outer segment (ROS) phagocytosis and digestion. MYO7A was knocked down in the human RPE cells by RNAi to test for a mutant phenotype in melanosome motility. RESULTS The distribution of MYO7A in the RPE of human and mouse was found to be comparable, both in vivo and in primary cultures. Primary cultures of human RPE cells phagocytosed and digested ROSs with kinetics comparable to that of primary cultures of mouse RPE cells. Melanosome motility was also comparable, and, after RNAi knockdown, consisted of longer-range fast movements characteristic of melanosomes in shaker1 RPE. CONCLUSIONS The localization and function of MYO7A in human RPE cells is comparable to that in mouse RPE cells. Although shaker1 retinas do not undergo degeneration, correction of mutant phenotypes in the shaker1 RPE represents a valid preclinical test for potential therapeutic treatments.
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Affiliation(s)
- Daniel Gibbs
- Department of Pharmacology, University of California at San Diego School of Medicine, La Jolla, California, USA
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