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Martemyanov KA, Sampath AP. The Transduction Cascade in Retinal ON-Bipolar Cells: Signal Processing and Disease. Annu Rev Vis Sci 2017; 3:25-51. [PMID: 28715957 DOI: 10.1146/annurev-vision-102016-061338] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Our robust visual experience is based on the reliable transfer of information from our photoreceptor cells, the rods and cones, to higher brain centers. At the very first synapse of the visual system, information is split into two separate pathways, ON and OFF, which encode increments and decrements in light intensity, respectively. The importance of this segregation is borne out in the fact that receptive fields in higher visual centers maintain a separation between ON and OFF regions. In the past decade, the molecular mechanisms underlying the generation of ON signals have been identified, which are unique in their use of a G-protein signaling cascade. In this review, we consider advances in our understanding of G-protein signaling in ON-bipolar cell (BC) dendrites and how insights about signaling have emerged from visual deficits, mostly night blindness. Studies of G-protein signaling in ON-BCs reveal an intricate mechanism that permits the regulation of visual sensitivity over a wide dynamic range.
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Affiliation(s)
| | - Alapakkam P Sampath
- Jules Stein Eye Institute, University of California, Los Angeles, California 90095;
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202
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Kumaran N, Moore AT, Weleber RG, Michaelides M. Leber congenital amaurosis/early-onset severe retinal dystrophy: clinical features, molecular genetics and therapeutic interventions. Br J Ophthalmol 2017; 101:1147-1154. [PMID: 28689169 PMCID: PMC5574398 DOI: 10.1136/bjophthalmol-2016-309975] [Citation(s) in RCA: 195] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 04/26/2017] [Accepted: 04/30/2017] [Indexed: 12/29/2022]
Abstract
Leber congenital amaurosis (LCA) and early-onset severe retinal dystrophy (EOSRD) are both genetically and phenotypically heterogeneous, and characterised clinically by severe congenital/early infancy visual loss, nystagmus, amaurotic pupils and markedly reduced/absent full-field electroretinograms. The vast genetic heterogeneity of inherited retinal disease has been established over the last 10 - 20 years, with disease-causing variants identified in 25 genes to date associated with LCA/EOSRD, accounting for 70–80% of cases, with thereby more genes yet to be identified. There is now far greater understanding of the structural and functional associations seen in the various LCA/EOSRD genotypes. Subsequent development/characterisation of LCA/EOSRD animal models has shed light on the underlying pathogenesis and allowed the demonstration of successful rescue with gene replacement therapy and pharmacological intervention in multiple models. These advancements have culminated in more than 12 completed, ongoing and anticipated phase I/II and phase III gene therapy and pharmacological human clinical trials. This review describes the clinical and genetic characteristics of LCA/EOSRD and the differential diagnoses to be considered. We discuss in further detail the diagnostic clinical features, pathophysiology, animal models and human treatment studies and trials, in the more common genetic subtypes and/or those closest to intervention.
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Affiliation(s)
- Neruban Kumaran
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK.,University of California San Francisco, San Francisco CA, California, USA
| | - Richard G Weleber
- Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
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203
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Seitter H, Koschak A. Relevance of tissue specific subunit expression in channelopathies. Neuropharmacology 2017; 132:58-70. [PMID: 28669898 DOI: 10.1016/j.neuropharm.2017.06.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/22/2017] [Accepted: 06/28/2017] [Indexed: 12/27/2022]
Abstract
Channelopathies are a diverse group of human disorders that are caused by mutations in genes coding for ion channels or channel-regulating proteins. Several dozen channelopathies have been identified that involve both non-excitable cells as well as electrically active tissues like brain, skeletal and smooth muscle or the heart. In this review, we start out from the general question which ion channel genes are expressed tissue-selectively. We mined the human gene expression database Human Protein Atlas (HPA) for tissue-enriched ion channel genes and found 85 genes belonging to the ion channel families. Most of these genes were enriched in brain, testis and muscle and a complete list of the enriched ion channel genes is provided. We further focused on the tissue distribution of voltage-gated calcium channel (VGCC) genes including different brain areas and the retina based on the human gene expression from the FANTOM5 dataset. The expression data is complemented by an overview of the tissue-dependent aspects of L-type calcium channel (LTCC) function, dysfunction and pharmacology, as well as of their splice variants. Finally, we focus on the pathology of tissue-restricted LTCC channelopathies and their treatment options. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Hartwig Seitter
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, Innrain 80-82/III, 6020 Innsbruck, Austria
| | - Alexandra Koschak
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, Innrain 80-82/III, 6020 Innsbruck, Austria.
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204
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Neuillé M, Cao Y, Caplette R, Guerrero-Given D, Thomas C, Kamasawa N, Sahel JA, Hamel CP, Audo I, Picaud S, Martemyanov KA, Zeitz C. LRIT3 Differentially Affects Connectivity and Synaptic Transmission of Cones to ON- and OFF-Bipolar Cells. Invest Ophthalmol Vis Sci 2017; 58:1768-1778. [PMID: 28334377 PMCID: PMC5374884 DOI: 10.1167/iovs.16-20745] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Purpose Mutations in LRIT3 lead to complete congenital stationary night blindness (cCSNB). Using a cCSNB mouse model lacking Lrit3 (nob6), we recently have shown that LRIT3 has a role in the correct localization of TRPM1 (transient receptor potential melastatin 1) to the dendritic tips of ON-bipolar cells (BCs), contacting both rod and cone photoreceptors. Furthermore, postsynaptic clustering of other mGluR6 cascade components is selectively eliminated at the dendritic tips of cone ON-BCs. The purpose of this study was to further define the role of LRIT3 in structural and functional organization of cone synapses. Methods Exhaustive electroretinogram analysis was performed in a patient with LRIT3 mutations. Multielectrode array recordings were performed at the level of retinal ganglion cells in nob6 mice. Targeting of GluR1 and GluR5 at the dendritic tips of OFF-BCs in nob6 retinas was assessed by immunostaining and confocal microscopy. The ultrastructure of photoreceptor synapses was evaluated by electron microscopy in nob6 mice. Results The patient with LRIT3 mutations had a selective ON-BC dysfunction with relatively preserved OFF-BC responses. In nob6 mice, complete lack of ON-pathway function with robust, yet altered signaling processing in OFF-pathways was detected. Consistent with these observations, molecules essential for the OFF-BC signaling were normally targeted to the synapse. Finally, synaptic contacts made by ON-BC but not OFF-BC neurons with the cone pedicles were disorganized without ultrastructural alterations in cone terminals, horizontal cell processes, or synaptic ribbons. Conclusions These results suggest that LRIT3 is likely involved in coordination of the transsynaptic communication between cones and ON-BCs during synapse formation and function.
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Affiliation(s)
- Marion Neuillé
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida United States
| | - Romain Caplette
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
| | | | - Connon Thomas
- Max Planck Florida Institute for Neuroscience, Jupiter, Florida United States
| | - Naomi Kamasawa
- Max Planck Florida Institute for Neuroscience, Jupiter, Florida United States
| | - José-Alain Sahel
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France 4CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France 5Institute of Ophthalmology, University College of London, London, United Kingdom 6Fondation Ophtalmologique Adolphe de Rothschild, Paris, France 8Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Christian P Hamel
- INSERM U583, Physiopathologie et thérapie des déficits sensoriels et moteurs, Institut des Neurosciences de Montpellier, Hôpital Saint-Eloi, Montpellier, France
| | - Isabelle Audo
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France 4CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France 5Institute of Ophthalmology, University College of London, London, United Kingdom
| | - Serge Picaud
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida United States
| | - Christina Zeitz
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
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205
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Hove MN, Kilic-Biyik KZ, Trotter A, Grønskov K, Sander B, Larsen M, Carroll J, Bech-Hansen T, Rosenberg T. Clinical Characteristics, Mutation Spectrum, and Prevalence of Åland Eye Disease/Incomplete Congenital Stationary Night Blindness in Denmark. Invest Ophthalmol Vis Sci 2017; 57:6861-6869. [PMID: 28002560 PMCID: PMC5215230 DOI: 10.1167/iovs.16-19445] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To assess clinical characteristics, foveal structure, mutation spectrum, and prevalence rate of Åland eye disease (AED)/incomplete congenital stationary night blindness (iCSNB). Methods A retrospective survey included individuals diagnosed with AED at a national low-vision center from 1980 to 2014. A subset of affected males underwent ophthalmologic examinations including psychophysical tests, full-field electroretinography, and spectral-domain optical coherence tomography. Results Over the 34-year period, 74 individuals from 35 families were diagnosed with AED. Sixty individuals from 29 families participated in a follow-up study of whom 59 harbored a CACNA1F mutation and 1 harbored a CABP4 mutation. Among the subjects with a CACNA1F mutation, subnormal visual acuity was present in all, nystagmus was present in 63%, and foveal hypoplasia was observed in 25/43 subjects. Foveal pit volume was significantly reduced as compared to normal (P < 0.0001). Additionally, outer segment length at the fovea was measured in 46 subjects and found to be significantly reduced as compared to normal (P < 0.001). Twenty-nine CACNA1F variations were detected among 34 families in the total cohort, and a novel CABP4 variation was identified in one family. The estimated mean birth prevalence rate was 1 per 22,000 live-born males. Conclusions Our data support the viewpoint that AED, iCSNB, and X-linked cone–rod dystrophy 3 are designations that refer to a broad, continuous spectrum of clinical appearances caused in the majority by a variety of mutations in CACNA1F. We argue that the original designation AED should be used for this entity.
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Affiliation(s)
- Marianne N Hove
- Department of Ophthalmology, National Eye Clinic for the Visually Impaired and Kennedy Center, Rigshospitalet, Glostrup, Denmark 2Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark
| | - Kevser Z Kilic-Biyik
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark 3Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alana Trotter
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Karen Grønskov
- Clinical Genetic Clinic, Kennedy Center, Rigshospitalet, Copenhagen, Denmark
| | - Birgit Sander
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark 3Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael Larsen
- Department of Ophthalmology, National Eye Clinic for the Visually Impaired and Kennedy Center, Rigshospitalet, Glostrup, Denmark 2Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark 3Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Joseph Carroll
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Torben Bech-Hansen
- Department of Medical Genetics, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Thomas Rosenberg
- Department of Ophthalmology, National Eye Clinic for the Visually Impaired and Kennedy Center, Rigshospitalet, Glostrup, Denmark 3Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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206
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Beyeler M, Rokem A, Boynton GM, Fine I. Learning to see again: biological constraints on cortical plasticity and the implications for sight restoration technologies. J Neural Eng 2017; 14:051003. [PMID: 28612755 DOI: 10.1088/1741-2552/aa795e] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The 'bionic eye'-so long a dream of the future-is finally becoming a reality with retinal prostheses available to patients in both the US and Europe. However, clinical experience with these implants has made it apparent that the visual information provided by these devices differs substantially from normal sight. Consequently, the ability of patients to learn to make use of this abnormal retinal input plays a critical role in whether or not some functional vision is successfully regained. The goal of the present review is to summarize the vast basic science literature on developmental and adult cortical plasticity with an emphasis on how this literature might relate to the field of prosthetic vision. We begin with describing the distortion and information loss likely to be experienced by visual prosthesis users. We then define cortical plasticity and perceptual learning, and describe what is known, and what is unknown, about visual plasticity across the hierarchy of brain regions involved in visual processing, and across different stages of life. We close by discussing what is known about brain plasticity in sight restoration patients and discuss biological mechanisms that might eventually be harnessed to improve visual learning in these patients.
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Affiliation(s)
- Michael Beyeler
- Department of Psychology, University of Washington, Seattle, WA, United States of America. Institute for Neuroengineering, University of Washington, Seattle, WA, United States of America. eScience Institute, University of Washington, Seattle, WA, United States of America
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207
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Actions and Regulation of Ionotropic Cannabinoid Receptors. ADVANCES IN PHARMACOLOGY 2017; 80:249-289. [PMID: 28826537 DOI: 10.1016/bs.apha.2017.04.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Almost three decades have passed since the identification of the two specific metabotropic receptors mediating cannabinoid pharmacology. Thereafter, many cannabinoid effects, both at central and peripheral levels, have been well documented and characterized. However, numerous evidences demonstrated that these pharmacological actions could not be attributable solely to the activation of CB1 and CB2 receptors since several important cannabimimetic actions have been found in biological systems lacking CB1 or CB2 gene such as in specific cell lines or transgenic mice. It is now well accepted that, beyond their receptor-mediated effects, these molecules can act also via CB1/CB2-receptor-independent mechanism. Cannabinoids have been demonstrated to modulate several voltage-gated channels (including Ca2+, Na+, and various type of K+ channels), ligand-gated ion channels (i.e., GABA, glycine), and ion-transporting membranes proteins such as transient potential receptor class (TRP) channels. The first direct, cannabinoid receptor-independent interaction was reported on the function of serotonin 5-HT3 receptor-ion channel complex. Similar effects were reported also on the other above mentioned ion channels. In the early ninety, studies searching for endogenous modulators of L-type Ca2+ channels identified anandamide as ligand for L-type Ca2+ channel. Later investigations indicated that other types of Ca2+ currents are also affected by endocannabinoids, and, in the late ninety, it was discovered that endocannabinoids activate the vanilloid receptor subtype 1 (TRPV1), and nowadays, it is known that (endo)cannabinoids gate at least five distinct TRP channels. This chapter focuses on cannabinoid regulation of ion channels and lays special emphasis on their action at transient receptor channels.
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208
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Brodsky MC. Marshall M. Parks Memorial Lecture: Ocular Motor Misbehavior in Children: Where Neuro-Ophthalmology Meets Strabismus. Ophthalmology 2017; 124:835-842. [PMID: 28385301 DOI: 10.1016/j.ophtha.2017.01.050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/24/2017] [Accepted: 01/26/2017] [Indexed: 01/19/2023] Open
Abstract
Clinical diagnosis has been supplemented by neuroimaging advances, genetic discoveries, and molecular research to generate new neurobiological discoveries pertaining to early maldevelopment of ocular motor control systems. In this focused review, I examine recent paradigm shifts that have transformed our understanding of pediatric ocular motor disease at the prenuclear and infranuclear levels. The pathogenesis of complex ocular motor disorders, such as paradoxical pupillary constriction to darkness, benign tonic upgaze of infancy, congenital fibrosis syndrome, and the constellation of unique eye movements that accompany Joubert syndrome, are elucidated.
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Affiliation(s)
- Michael C Brodsky
- Departments of Ophthalmology and Neurology, Mayo Clinic, Rochester, Minnesota.
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209
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Peachey NS, Hasan N, FitzMaurice B, Burrill S, Pangeni G, Karst SY, Reinholdt L, Berry ML, Strobel M, Gregg RG, McCall MA, Chang B. A missense mutation in Grm6 reduces but does not eliminate mGluR6 expression or rod depolarizing bipolar cell function. J Neurophysiol 2017; 118:845-854. [PMID: 28490646 DOI: 10.1152/jn.00888.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 05/03/2017] [Accepted: 05/03/2017] [Indexed: 01/01/2023] Open
Abstract
GRM6 encodes the metabotropic glutamate receptor 6 (mGluR6) used by retinal depolarizing bipolar cells (DBCs). Mutations in GRM6 lead to DBC dysfunction and underlie the human condition autosomal recessive complete congenital stationary night blindness. Mouse mutants for Grm6 are important models for this condition. Here we report a new Grm6 mutant, identified in an electroretinogram (ERG) screen of mice maintained at The Jackson Laboratory. The Grm6nob8 mouse has a reduced-amplitude b-wave component of the ERG, which reflects light-evoked DBC activity. Sequencing identified a missense mutation that converts a highly conserved methionine within the ligand binding domain to leucine (p.Met66Leu). Consistent with prior studies of Grm6 mutant mice, the laminar size and structure in the Grm6nob8 retina were comparable to control. The Grm6nob8 phenotype is distinguished from other Grm6 mutants that carry a null allele by a reduced but not absent ERG b-wave, decreased but present expression of mGluR6 at DBC dendritic tips, and mislocalization of mGluR6 to DBC somas. Consistent with a reduced but not absent b-wave, there were a subset of retinal ganglion cells whose responses to light onset have times to peak within the range of those in control retinas. These data indicate that the p.Met66Leu mutant mGluR6 is trafficked less than control. However, the mGluR6 that is localized to the DBC dendritic tips is able to initiate DBC signal transduction. The Grm6nob8 mouse extends the Grm6 allelic series and will be useful for elucidating the role of mGluR6 in DBC signal transduction and in human disease.NEW & NOTEWORTHY This article describes a mouse model of the human disease complete congenital stationary night blindness in which the mutation reduces but does not eliminate GRM6 expression and bipolar cell function, a distinct phenotype from that seen in other Grm6 mouse models.
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Affiliation(s)
- Neal S Peachey
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio.,Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio.,Department of Ophthalmology, Cleveland Clinic College of Medicine of Case Western Reserve University, Cleveland, Ohio
| | - Nazarul Hasan
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky
| | | | | | - Gobinda Pangeni
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky; and
| | | | | | | | | | - Ronald G Gregg
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky.,Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky; and
| | - Maureen A McCall
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky; and.,Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, Maine;
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210
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Li L, Chen Y, Jiao X, Jin C, Jiang D, Tanwar M, Ma Z, Huang L, Ma X, Sun W, Chen J, Ma Y, M'hamdi O, Govindarajan G, Cabrera PE, Li J, Gupta N, Naeem MA, Khan SN, Riazuddin S, Akram J, Ayyagari R, Sieving PA, Riazuddin SA, Hejtmancik JF. Homozygosity Mapping and Genetic Analysis of Autosomal Recessive Retinal Dystrophies in 144 Consanguineous Pakistani Families. Invest Ophthalmol Vis Sci 2017; 58:2218-2238. [PMID: 28418496 PMCID: PMC5397137 DOI: 10.1167/iovs.17-21424] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Purpose The Pakistan Punjab population has been a rich source for identifying genes causing or contributing to autosomal recessive retinal degenerations (arRD). This study was carried out to delineate the genetic architecture of arRD in the Pakistani population. Methods The genetic origin of arRD in a total of 144 families selected only for having consanguineous marriages and multiple members affected with arRD was examined. Of these, causative mutations had been identified in 62 families while only the locus had been identified for an additional 15. The remaining 67 families were subjected to homozygosity exclusion mapping by screening of closely flanking microsatellite markers at 180 known candidate genes/loci followed by sequencing of the candidate gene for pathogenic changes. Results Of these 67 families subjected to homozygosity mapping, 38 showed homozygosity for at least one of the 180 regions, and sequencing of the corresponding genes showed homozygous cosegregating mutations in 27 families. Overall, mutations were detected in approximately 61.8 % (89/144) of arRD families tested, with another 10.4% (15/144) being mapped to a locus but without a gene identified. Conclusions These results suggest the involvement of unmapped novel genes in the remaining 27.8% (40/144) of families. In addition, this study demonstrates that homozygosity mapping remains a powerful tool for identifying the genetic defect underlying genetically heterogeneous arRD disorders in consanguineous marriages for both research and clinical applications.
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Affiliation(s)
- Lin Li
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China 2Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Yabin Chen
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Xiaodong Jiao
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Chongfei Jin
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 3Department of Medicine, Brookdale University Hospital and Medical Center, New York, New York, United States
| | - Dan Jiang
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Mukesh Tanwar
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 4Department of Genetics, Maharshi Dayanand University Rohtak, Haryana, India
| | - Zhiwei Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Li Huang
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 5State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Xiaoyin Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 6Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Wenmin Sun
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 5State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Jianjun Chen
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 7Department of Ophthalmology, Shanghai Tenth People's Hospital, and Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Yan Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Oussama M'hamdi
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Gowthaman Govindarajan
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Patricia E Cabrera
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Jiali Li
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 5State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Nikhil Gupta
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shaheen N Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan 9Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan 10National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan 10National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California-San Diego, La Jolla, California, United States
| | - Paul A Sieving
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - S Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States 14McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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211
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Kurata K, Hosono K, Hotta Y. Long-Term Clinical Course in a Patient with Complete Congenital Stationary Night Blindness. Case Rep Ophthalmol 2017; 8:237-244. [PMID: 28512427 PMCID: PMC5422747 DOI: 10.1159/000462961] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/10/2017] [Indexed: 11/30/2022] Open
Abstract
Background This report describes a 45-year-old man with complete congenital stationary night blindness (CSNB1) who has been followed up for 38 years. Case The patient first visited our hospital as a 7-year-old boy with a complaint of low visual acuity. Best corrected visual acuity (BCVA) was 0.5 in the right eye and 0.6 in the left eye. The refractive error was approximately −5.0 D in both eyes. The fundus showed only myopic changes. A bright-flash electroretinogram (ERG) revealed a negative configuration. We diagnosed CSNB and corrected the refractive error with glasses. We continued to monitor the ERG and various waveform components as well as visual acuity and the appearance of the fundus. All NYX exons were screened for a causative mutation by polymerase chain reaction amplification, and direct sequencing was performed. Results By 10 years of age, BCVA had increased to 0.8 on the right and 0.9 on the left, with little change thereafter. The fundus continued to show only myopic changes. No changes were seen in the amplitude or implicit time of the a-wave or b-wave or in the b/a-wave ratio. A novel hemizygous insertion mutation, c.1205_1206insT, p.(Glu404Argfs*89), was detected in exon 2 of the NYX gene. Conclusion To our knowledge, this is the longest follow-up of a patient with CSNB1. No changes in the clinical course have been seen during follow-up. We believe that it is important to continue observations and accumulate clinical data for prognostic purposes on patients with CSNB1.
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Affiliation(s)
- Kentaro Kurata
- Department of Ophthalmology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Katsuhiro Hosono
- Department of Ophthalmology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yoshihiro Hotta
- Department of Ophthalmology, Hamamatsu University School of Medicine, Hamamatsu, Japan
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Chen FK, Chew AL, Zhang D, Chen SC, Chelva E, Chandrasekera E, Koay EMH, Forrester J, McLenachan S. Acute progressive paravascular placoid neuroretinopathy with negative-type electroretinography in paraneoplastic retinopathy. Doc Ophthalmol 2017; 134:227-235. [PMID: 28382556 PMCID: PMC5427140 DOI: 10.1007/s10633-017-9587-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 03/30/2017] [Indexed: 11/28/2022]
Abstract
PURPOSE Paraneoplastic retinopathy can be the first manifestation of systemic malignancy. A subset of paraneoplastic retinopathy is characterized by negative-type electroretinography (ERG) without fundus abnormality. Here we describe the multimodal imaging and clinico-pathological correlation of a unique case of acute progressive paravascular placoid neuroretinopathy with suspected retinal depolarizing bipolar cell dysfunction preceding the diagnosis of metastatic small cell carcinoma of the prostate. METHODS ERG was performed according to the International Society for Clinical Electrophysiology of Vision standards. Imaging modalities included near-infrared reflectance, blue-light autofluorescence, fluorescein and indocyanine green angiographies, spectral domain optical coherence tomography, ultra-widefield colour and green-light autofluorescence imaging, microperimetry and adaptive optics imaging. Patient serum was screened for anti-retinal antibodies using western blotting. Immunostaining and histological analyses were performed on sections from human retinal tissues and a patient prostate biopsy. RESULTS Serial multimodal retinal imaging, microperimetry and adaptive optics photography demonstrated a paravascular distribution of placoid lesions characterized by hyper-reflectivity within the outer nuclear layer resembling type 2 acute macular neuroretinopathy. There was no visible lesion within the inner nuclear layer despite electronegative-type ERG. Six months later, the patient presented with metastatic small cell carcinoma of the prostate. Tumour cells were immunopositive for glyceraldehyde-3-phosphate dehydrogenase, enolase and recoverin as well as neuroendocrine markers. The patient's serum reacted to cytoplasmic and nuclear antigens in the prostate biopsy and in human retina. Anti-retinal antibodies against several antigens were detected by both commercial and in-house western blots. CONCLUSIONS A spectrum of autoreactive anti-retinal antibodies is associated with a unique phenotype of acute progressive paravascular placoid neuroretinopathy resulting in degeneration of photoreceptor cells, inner retinal dysfunction and classic electronegative ERG in paraneoplastic retinopathy. Detailed clinical, functional and immunological phenotyping of paraneoplastic retinopathy illustrated the complex mechanism of paraneoplastic syndrome.
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Affiliation(s)
- Fred K Chen
- Centre for Ophthalmology and Vision Science, The University of Western Australia, Perth, WA, Australia.,Lions Eye Institute, Perth, WA, Australia.,Department of Ophthalmology, Royal Perth Hospital, Perth, WA, Australia
| | - Avenell L Chew
- Centre for Ophthalmology and Vision Science, The University of Western Australia, Perth, WA, Australia.,Lions Eye Institute, Perth, WA, Australia
| | - Dan Zhang
- Lions Eye Institute, Perth, WA, Australia
| | | | - Enid Chelva
- Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, WA, Australia
| | | | - Eleanor M H Koay
- PathWest Laboratory Medicine WA, Fiona Stanley Hospital, Perth, WA, Australia
| | - John Forrester
- Centre for Ophthalmology and Vision Science, The University of Western Australia, Perth, WA, Australia.,Lions Eye Institute, Perth, WA, Australia.,The Institute of Medical Sciences, The University of Aberdeen, Scotland, UK
| | - Samuel McLenachan
- Centre for Ophthalmology and Vision Science, The University of Western Australia, Perth, WA, Australia. .,Lions Eye Institute, Perth, WA, Australia. .,Department of Ophthalmology, Royal Perth Hospital, Perth, WA, Australia. .,Ocular Tissue Engineering Laboratory, Lions Eye Institute, 2 Verdun Street, Nedlands, WA, 6009, Australia.
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213
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Wang Y, Fehlhaber KE, Sarria I, Cao Y, Ingram NT, Guerrero-Given D, Throesch B, Baldwin K, Kamasawa N, Ohtsuka T, Sampath AP, Martemyanov KA. The Auxiliary Calcium Channel Subunit α2δ4 Is Required for Axonal Elaboration, Synaptic Transmission, and Wiring of Rod Photoreceptors. Neuron 2017; 93:1359-1374.e6. [PMID: 28262416 PMCID: PMC5364038 DOI: 10.1016/j.neuron.2017.02.021] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 12/31/2016] [Accepted: 02/08/2017] [Indexed: 11/24/2022]
Abstract
Neural circuit wiring relies on selective synapse formation whereby a presynaptic release apparatus is matched with its cognate postsynaptic machinery. At metabotropic synapses, the molecular mechanisms underlying this process are poorly understood. In the mammalian retina, rod photoreceptors form selective contacts with rod ON-bipolar cells by aligning the presynaptic voltage-gated Ca2+ channel directing glutamate release (CaV1.4) with postsynaptic mGluR6 receptors. We show this coordination requires an extracellular protein, α2δ4, which complexes with CaV1.4 and the rod synaptogenic mediator, ELFN1, for trans-synaptic alignment with mGluR6. Eliminating α2δ4 in mice abolishes rod synaptogenesis and synaptic transmission to rod ON-bipolar cells, and disrupts postsynaptic mGluR6 clustering. We further find that in rods, α2δ4 is crucial for organizing synaptic ribbons and setting CaV1.4 voltage sensitivity. In cones, α2δ4 is essential for CaV1.4 function, but is not required for ribbon organization, synaptogenesis, or synaptic transmission. These findings offer insights into retinal pathologies associated with α2δ4 dysfunction.
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Affiliation(s)
- Yuchen Wang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Katherine E Fehlhaber
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Ignacio Sarria
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Norianne T Ingram
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Debbie Guerrero-Given
- Electron Microscopy Core Facility, Max Planck Florida Institute, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Ben Throesch
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92121, USA
| | - Kristin Baldwin
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92121, USA
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Toshihisa Ohtsuka
- Department of Biochemistry, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Alapakkam P Sampath
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
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214
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Abstract
PURPOSE Multimodal imaging has not been documented for CABP4-related retinopathy. In this study, we describe optical coherence tomography (OCT) and fundus autofluorescence findings for five genetically confirmed cases. METHODS Retrospective case series. RESULTS Four patients with the previously described homozygous Saudi CABP4 founder mutation c.81_82insA (p.Pro28ThrfsX44) and one patient with the homozygous mutation c.1A>G (p.Met1?) in CABP4 were examined. The ages ranged between 9 and 16 years at last follow-up, and the duration of follow-up ranged from 2 to 12 years. Foveal thickness was reduced ranging between 175 and 212 micrometers. Wide field imaging including fundus autofluorescence was unremarkable. All patients presented with a negative electroretinogram, with a variable amount of cone and rod dysfunction. Over follow-up, there was no electroretinographic indication of any progressive retinal dysfunction. CONCLUSIONS Foveal thinning is a feature of CABP4 retinopathy. Normal autofluorescence is consistent with inner retinal dysfunction and suggests the condition could be amenable to gene therapy. Retinal dysfunction was stable throughout follow-up.
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Affiliation(s)
- Patrik Schatz
- a Vitreoretinal Division, King Khaled Eye Specialist Hospital , Riyadh , Saudi Arabia.,b Department of Ophthalmology, Clinical Sciences , Scane County University Hospital, University of Lund , Lund , Sweden
| | | | - Arif O Khan
- d Eye Institute, Cleveland Clinic Abu Dhabi , Abu Dhabi , United Arab Emirates
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215
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Maguire J, Parry NRA, Kremers J, Murray IJ, McKeefry D. The morphology of human rod ERGs obtained by silent substitution stimulation. Doc Ophthalmol 2017; 134:11-24. [PMID: 28091887 PMCID: PMC5274650 DOI: 10.1007/s10633-017-9571-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 01/05/2017] [Indexed: 11/10/2022]
Abstract
Purpose To record transient ERGs from the light-adapted human retina using silent substitution stimuli which selectively reflect the activity of rod photoreceptors. We aim to describe the morphology of these waveforms and examine how they are affected by the use of less selective stimuli and by retinal pathology. Methods Rod-isolating stimuli with square-wave temporal profiles (250/250 ms onset/offset) were presented using a 4 primary LED ganzfeld stimulator. Experiment 1: ERGs were recorded using a rod-isolating stimulus (63 ph Td, rod contrast, Crod = 0.25) from a group (n = 20) of normal trichromatic observers. Experiment 2: Rod ERGs were recorded from a group (n = 5) using a rod-isolating stimulus (Crod = 0.25) which varied in retinal illuminance from 40 to 10,000 ph Td. Experiment 3: ERGs were elicited using 2 kinds of non-isolating stimuli; (1) broadband and (2) rod-isolating stimuli which contained varying degrees of L- and M-cone excitation. Experiment 4: Rod ERGs were recorded from two patient groups with rod monochromacy (n = 3) and CSNB (type 1; n = 2). Results The rod-isolated ERGs elicited from normal subjects had a waveform with a positive onset component followed by a negative offset. Response amplitude was maximal at retinal illuminances <100 ph Td and was virtually abolished at 400 ph Td. The use of non-selective stimuli altered the ERG waveform eliciting more photopic-like ERG responses. Rod ERGs recorded from rod monochromats had similar features to those recorded from normal trichromats, in contrast to those recorded from participants with CSNB which had an electronegative appearance. Conclusions Our results demonstrate that ERGs elicited by silent substitution stimuli can selectively reflect the operation of rod photoreceptors in the normal, light-adapted human retina.
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Affiliation(s)
- J Maguire
- Bradford School of Optometry and Vision Sciences, University of Bradford, Bradford, W. Yorkshire, BD7 1DP, UK
| | - N R A Parry
- Bradford School of Optometry and Vision Sciences, University of Bradford, Bradford, W. Yorkshire, BD7 1DP, UK.,Vision Science Centre, Manchester Royal Eye Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.,Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - J Kremers
- Bradford School of Optometry and Vision Sciences, University of Bradford, Bradford, W. Yorkshire, BD7 1DP, UK.,Department of Ophthalmology, University Hospital Erlangen, Erlangen, Germany
| | - I J Murray
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - D McKeefry
- Bradford School of Optometry and Vision Sciences, University of Bradford, Bradford, W. Yorkshire, BD7 1DP, UK.
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216
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Xie P, Zhang Y. Why choose 9-cis retinal for therapy of congenital stationary night blindness caused by G90D rhodopsin? Theor Chem Acc 2016. [DOI: 10.1007/s00214-016-2039-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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217
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Méjécase C, Laurent-Coriat C, Mayer C, Poch O, Mohand-Saïd S, Prévot C, Antonio A, Boyard F, Condroyer C, Michiels C, Blanchard S, Letexier M, Saraiva JP, Sahel JA, Audo I, Zeitz C. Identification of a Novel Homozygous Nonsense Mutation Confirms the Implication of GNAT1 in Rod-Cone Dystrophy. PLoS One 2016; 11:e0168271. [PMID: 27977773 PMCID: PMC5158031 DOI: 10.1371/journal.pone.0168271] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/29/2016] [Indexed: 12/11/2022] Open
Abstract
GNAT1, encoding the transducin subunit Gα, is an important element of the phototransduction cascade. Mutations in this gene have been associated with autosomal dominant and autosomal recessive congenital stationary night blindness. Recently, a homozygous truncating GNAT1 mutation was identified in a patient with late-onset rod-cone dystrophy. After exclusion of mutations in genes underlying progressive inherited retinal disorders, by targeted next generation sequencing, a 32 year-old male sporadic case with severe rod-cone dystrophy and his unaffected parents were investigated by whole exome sequencing. This led to the identification of a homozygous nonsense variant, c.963C>A p.(Cys321*) in GNAT1, which was confirmed by Sanger sequencing. The mother was heterozygous for this variant whereas the variant was absent in the father. c.963C>A p.(Cys321*) is predicted to produce a shorter protein that lacks critical sites for the phototransduction cascade. Our work confirms that the phenotype and the mode of inheritance associated with GNAT1 variants can vary from autosomal dominant, autosomal recessive congenital stationary night blindness to autosomal recessive rod-cone dystrophy.
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Affiliation(s)
- Cécile Méjécase
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Claudine Mayer
- Institut Pasteur, Paris, France
- CNRS, UMR 3528, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Olivier Poch
- Université de Strasbourg CNRS-Icube, UMR 7357, LBGI, Faculté de Médecine, Strasbourg, France
| | - Saddek Mohand-Saïd
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France
| | - Camille Prévot
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France
- Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
| | - Aline Antonio
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France
| | - Fiona Boyard
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Christel Condroyer
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Christelle Michiels
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | | | | | - José-Alain Sahel
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France
- Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
- Institute of Ophthalmology, University College of London, London, United Kingdom
- Academie des Sciences, Institut de France, Paris, France
| | - Isabelle Audo
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France
- Institute of Ophthalmology, University College of London, London, United Kingdom
- * E-mail: (IA); (CZ)
| | - Christina Zeitz
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
- * E-mail: (IA); (CZ)
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218
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The mutation p.E113K in the Schiff base counterion of rhodopsin is associated with two distinct retinal phenotypes within the same family. Sci Rep 2016; 6:36208. [PMID: 27812022 PMCID: PMC5095885 DOI: 10.1038/srep36208] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 10/12/2016] [Indexed: 02/05/2023] Open
Abstract
The diagnoses of retinitis pigmentosa (RP) and stationary night blindness (CSNB) are two distinct clinical entities belonging to a group of clinically and genetically heterogeneous retinal diseases. The current study focused on the identification of causative mutations in the RP-affected index patient and in several members of the same family that reported a phenotype resembling CSNB. Ophthalmological examinations of the index patient confirmed a typical form of RP. In contrast, clinical characterizations and ERGs of another affected family member showed the Riggs-type CSNB lacking signs of RP. Applying whole exome sequencing we detected the non-synonymous substitution c.337G > A, p.E113 K in the rhodopsin (RHO) gene. The mutation co-segregated with the diseases. The identification of the pathogenic variant p.E113 K is the first description of a naturally-occurring mutation in the Schiff base counterion of RHO in human patients. The heterozygous mutation c.337G > A in exon 1 was confirmed in the index patient as well as in five CSNB-affected relatives. This pathogenic sequence change was excluded in a healthy family member and in 199 ethnically matched controls. Our findings suggest that a mutation in the biochemically well-characterized counterion p.E113 in RHO can be associated with RP or Riggs-type CSNB, even within the same family.
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219
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Zhou L, Li T, Xing YQ, Li Y, Wu QS, Zhang MJ. Novel TRPM1 mutations in two Chinese families with early-onset high myopia, with or without complete congenital stationary night blindness. Int J Ophthalmol 2016; 9:1396-1402. [PMID: 27803854 DOI: 10.18240/ijo.2016.10.05] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 05/25/2015] [Indexed: 12/29/2022] Open
Abstract
AIM To investigate the relationship between high myopia [with or without complete congenital stationary night blindness (CSNB1)] and TRPM1 and NYX. METHODS Two unrelated families with early-onset high myopia (eoHM) and 96 normal controls were recruited. Sanger sequencing or clone sequencing were used for mutation screening. Further analyses of the available family members and the 96 normal controls were subsequently conducted to obtain additional evidence of the pathogenicity of these variants. The initial diagnosis of the probands was eoHM. We performed a further comprehensive examination of the available family members after mutations were detected in TRPM1 or NYX. RESULTS Two novel compound heterozygous mutations in TRPM1 were detected in the recruited families. The proband in family A with eoHM carried a c.2594C>T missense mutation in exon 19 and a c.669+3_669+6delAAGT splicing mutation, which was co-segregated with CSNB1 in this family. A patient in family B with a compound heterozygous missense mutation (c.3262G>A and c.3250T>C) was detected. No mutations were found in NYX. These two identified compound heterozygous mutations were not found in the 96 normal controls. After further examination of the family members, the patients in family A could be diagnosed as eoHM with CSNB1. However due to the limited clinic data, the patient in family B cloud not clearly diagnosed as CSNB1. CONCLUSION This study has expanded the mutation spectrum of TRPM1 for CSNB1 and additional studies are needed to elucidate the association between isolated high myopia and TRPM1 and NYX.
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Affiliation(s)
- Lin Zhou
- Department of Ophthalmology, the Central Hospital of Enshi Autonomous Prefecture, Enshi Clinical College of Wuhan University, Enshi 445000, Hubei Province, China
| | - Tuo Li
- Department of Ophthalmology, the Central Hospital of Enshi Autonomous Prefecture, Enshi Clinical College of Wuhan University, Enshi 445000, Hubei Province, China
| | - Yi-Qiao Xing
- Department of Ophthalmology, Remin Hospital of Wuhan University, Wuhan 430060, Hubei Province, China
| | - Yin Li
- Department of Ophthalmology, the Central Hospital of Enshi Autonomous Prefecture, Enshi Clinical College of Wuhan University, Enshi 445000, Hubei Province, China
| | - Qing-Song Wu
- Department of Ophthalmology, the Central Hospital of Enshi Autonomous Prefecture, Enshi Clinical College of Wuhan University, Enshi 445000, Hubei Province, China
| | - Mao-Ju Zhang
- Department of Ophthalmology, the Central Hospital of Enshi Autonomous Prefecture, Enshi Clinical College of Wuhan University, Enshi 445000, Hubei Province, China
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220
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Carrigan M, Duignan E, Malone CPG, Stephenson K, Saad T, McDermott C, Green A, Keegan D, Humphries P, Kenna PF, Farrar GJ. Panel-Based Population Next-Generation Sequencing for Inherited Retinal Degenerations. Sci Rep 2016; 6:33248. [PMID: 27624628 PMCID: PMC5021935 DOI: 10.1038/srep33248] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 08/23/2016] [Indexed: 12/15/2022] Open
Abstract
Inherited retinopathies affect approximately two and a half million people globally, yet the majority of affected patients lack clear genetic diagnoses given the diverse range of genes and mutations implicated in these conditions. We present results from a next-generation sequencing study of a large inherited retinal disease patient population, with the goal of providing clear and actionable genetic diagnoses. Targeted sequencing was performed on 539 individuals from 309 inherited retinal disease pedigrees. Causative mutations were identified in the majority (57%, 176/309) of pedigrees. We report the association of many previously unreported variants with retinal disease, as well as new disease phenotypes associated with known genes, including the first association of the SLC24A1 gene with retinitis pigmentosa. Population statistics reporting the genes most commonly implicated in retinal disease in the cohort are presented, as are some diagnostic conundrums that can arise during such studies. Inherited retinal diseases represent an exemplar group of disorders for the application of panel-based next-generation sequencing as an effective tool for detection of causative mutations.
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Affiliation(s)
- Matthew Carrigan
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Emma Duignan
- Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | - Conor P G Malone
- Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | | | - Tahira Saad
- Mater Misericordiae University Hospital, Dublin, Ireland
| | - Ciara McDermott
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Andrew Green
- Our Lady's Children's Hospital, Crumlin, Dublin, Ireland
| | - David Keegan
- Mater Misericordiae University Hospital, Dublin, Ireland
| | - Peter Humphries
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Paul F Kenna
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland.,Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | - G Jane Farrar
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
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221
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Intermolecular Interaction between Anchoring Subunits Specify Subcellular Targeting and Function of RGS Proteins in Retina ON-Bipolar Neurons. J Neurosci 2016; 36:2915-25. [PMID: 26961947 DOI: 10.1523/jneurosci.3833-15.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In vertebrate retina, light responses generated by the rod photoreceptors are transmitted to the second-order neurons, the ON-bipolar cells (ON-BC), and this communication is indispensible for vision in dim light. In ON-BCs, synaptic transmission is initiated by the metabotropic glutamate receptor, mGluR6, that signals via the G-protein Go to control opening of the effector ion channel, TRPM1. A key role in this process belongs to the GTPase Activating Protein (GAP) complex that catalyzes Go inactivation upon light-induced suppression of glutamate release in rod photoreceptors, thereby driving ON-BC depolarization to changes in synaptic input. The GAP complex has a striking molecular complexity. It contains two Regulator of G-protein Signaling (RGS) proteins RGS7 and RGS11 that directly act on Go and two adaptor subunits: RGS Anchor Protein (R9AP) and the orphan receptor, GPR179. Here we examined the organizational principles of the GAP complex in ON-BCs. Biochemical experiments revealed that RGS7 binds to a conserved site in GPR179 and that RGS11 in vivo forms a complex only with R9AP. R9AP and GPR179 are further integrated via direct protein-protein interactions involving their cytoplasmic domains. Elimination of GPR179 prevents postsynaptic accumulation of R9AP. Furthermore, concurrent knock-out of both R9AP and RGS7 does not reconfigure the GAP complex and completely abolishes synaptic transmission, resulting in a novel mouse model of night blindness. Based on these results, we propose a model of hierarchical assembly and function of the GAP complex that supports ON-BCs visual signaling.
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222
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Dinet V, Ciccotosto GD, Delaunay K, Borras C, Ranchon-Cole I, Kostic C, Savoldelli M, El Sanharawi M, Jonet L, Pirou C, An N, Abitbol M, Arsenijevic Y, Behar-Cohen F, Cappai R, Mascarelli F. Amyloid Precursor-Like Protein 2 deletion-induced retinal synaptopathy related to congenital stationary night blindness: structural, functional and molecular characteristics. Mol Brain 2016; 9:64. [PMID: 27267879 PMCID: PMC4897877 DOI: 10.1186/s13041-016-0245-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 05/30/2016] [Indexed: 12/03/2022] Open
Abstract
Background Amyloid precursor protein knockout mice (APP-KO) have impaired differentiation of amacrine and horizontal cells. APP is part of a gene family and its paralogue amyloid precursor-like protein 2 (APLP2) has both shared as well as distinct expression patterns to APP, including in the retina. Given the impact of APP in the retina we investigated how APLP2 expression affected the retina using APLP2 knockout mice (APLP2-KO). Results Using histology, morphometric analysis with noninvasive imaging technique and electron microscopy, we showed that APLP2-KO retina displayed abnormal formation of the outer synaptic layer, accompanied with greatly impaired photoreceptor ribbon synapses in adults. Moreover, APLP2-KO displayed a significant decease in ON-bipolar, rod bipolar and type 2 OFF-cone bipolar cells (36, 21 and 63 %, respectively). Reduction of the number of bipolar cells was accompanied with disrupted dendrites, reduced expression of metabotropic glutamate receptor 6 at the dendritic tips and alteration of axon terminals in the OFF laminae of the inner plexiform layer. In contrast, the APP-KO photoreceptor ribbon synapses and bipolar cells were intact. The APLP2-KO retina displayed numerous phenotypic similarities with the congenital stationary night blindness, a non-progressive retinal degeneration disease characterized by the loss of night vision. The pathological phenotypes in the APLP2-KO mouse correlated to altered transcription of genes involved in pre- and postsynatic structure/function, including CACNA1F, GRM6, TRMP1 and Gα0, and a normal scotopic a-wave electroretinogram amplitude, markedly reduced scotopic electroretinogram b-wave and modestly reduced photopic cone response. This confirmed the impaired function of the photoreceptor ribbon synapses and retinal bipolar cells, as is also observed in congenital stationary night blindness. Since congenital stationary night blindness present at birth, we extended our analysis to retinal differentiation and showed impaired differentiation of different bipolar cell subtypes and an altered temporal sequence of development from OFF to ON laminae in the inner plexiform layer. This was associated with the altered expression patterns of bipolar cell generation and differentiation factors, including MATH3, CHX10, VSX1 and OTX2. Conclusions These findings demonstrate that APLP2 couples retina development and synaptic genes and present the first evidence that APLP2 expression may be linked to synaptic disease. Electronic supplementary material The online version of this article (doi:10.1186/s13041-016-0245-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Virginie Dinet
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Giuseppe D Ciccotosto
- Department of Pathology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Australia
| | - Kimberley Delaunay
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Céline Borras
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Isabelle Ranchon-Cole
- Laboratoire de Biophysique Sensorielle, Université Clermont 1, Clermont-Ferrand, France
| | - Corinne Kostic
- Unit of Gene Therapy & Stem Cell Biology, University of Lausanne, Jules-Gonin Eye Hospital, Lausanne, Switzerland
| | - Michèle Savoldelli
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Mohamed El Sanharawi
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Laurent Jonet
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Caroline Pirou
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Na An
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Marc Abitbol
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Yvan Arsenijevic
- Unit of Gene Therapy & Stem Cell Biology, University of Lausanne, Jules-Gonin Eye Hospital, Lausanne, Switzerland
| | - Francine Behar-Cohen
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Roberto Cappai
- Department of Pathology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Australia
| | - Frédéric Mascarelli
- Centre de Recherche des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France.
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223
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Hung SSC, McCaughey T, Swann O, Pébay A, Hewitt AW. Genome engineering in ophthalmology: Application of CRISPR/Cas to the treatment of eye disease. Prog Retin Eye Res 2016; 53:1-20. [PMID: 27181583 DOI: 10.1016/j.preteyeres.2016.05.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 04/30/2016] [Accepted: 05/04/2016] [Indexed: 12/12/2022]
Abstract
The Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) and CRISPR-associated protein (Cas) system has enabled an accurate and efficient means to edit the human genome. Rapid advances in this technology could results in imminent clinical application, and with favourable anatomical and immunological profiles, ophthalmic disease will be at the forefront of such work. There have been a number of breakthroughs improving the specificity and efficacy of CRISPR/Cas-mediated genome editing. Similarly, better methods to identify off-target cleavage sites have also been developed. With the impending clinical utility of CRISPR/Cas technology, complex ethical issues related to the regulation and management of the precise applications of human gene editing must be considered. This review discusses the current progress and recent breakthroughs in CRISPR/Cas-based gene engineering, and outlines some of the technical issues that must be addressed before gene correction, be it in vivo or in vitro, is integrated into ophthalmic care. We outline a clinical pipeline for CRISPR-based treatments of inherited eye diseases and provide an overview of the important ethical implications of gene editing and how these may influence the future of this technology.
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Affiliation(s)
- Sandy S C Hung
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Tristan McCaughey
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia; Department of Surgery, Monash University, Victoria, Australia
| | - Olivia Swann
- Menzies Institute for Medical Research, School of Medicine, University of Tasmania, Australia
| | - Alice Pébay
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Alex W Hewitt
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia; Menzies Institute for Medical Research, School of Medicine, University of Tasmania, Australia.
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224
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Vincent A, Audo I, Tavares E, Maynes J, Tumber A, Wright T, Li S, Michiels C, Condroyer C, MacDonald H, Verdet R, Sahel JA, Hamel CP, Zeitz C, Héon E, Banin E, Bocquet B, De Baere E, Casteels I, Defoort-Dhellemmes S, Drumare I, Friedburg C, Gottlob I, Jacobson S, Kellner U, Koenekoop R, Kohl S, Leroy B, Lorenz B, McLean R, Meire F, Meunier I, Munier F, de Ravel T, Reiff C, Mohand-Saïd S, Sharon D, Schorderet D, Schwartz S, Zanlonghi X. Biallelic Mutations in GNB3 Cause a Unique Form of Autosomal-Recessive Congenital Stationary Night Blindness. Am J Hum Genet 2016; 98:1011-1019. [PMID: 27063057 DOI: 10.1016/j.ajhg.2016.03.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 03/18/2016] [Indexed: 01/13/2023] Open
Abstract
Congenital stationary night blindness (CSNB) is a heterogeneous group of non-progressive inherited retinal disorders with characteristic electroretinogram (ERG) abnormalities. Riggs and Schubert-Bornschein are subtypes of CSNB and demonstrate distinct ERG features. Riggs CSNB demonstrates selective rod photoreceptor dysfunction and occurs due to mutations in genes encoding proteins involved in rod phototransduction cascade; night blindness is the only symptom and eye examination is otherwise normal. Schubert-Bornschein CSNB is a consequence of impaired signal transmission between the photoreceptors and bipolar cells. Schubert-Bornschein CSNB is subdivided into complete CSNB with an ON bipolar signaling defect and incomplete CSNB with both ON and OFF pathway involvement. Both subtypes are associated with variable degrees of night blindness or photophobia, reduced visual acuity, high myopia, and nystagmus. Whole-exome sequencing of a family screened negative for mutations in genes associated with CSNB identified biallelic mutations in the guanine nucleotide-binding protein subunit beta-3 gene (GNB3). Two siblings were compound heterozygous for a deletion (c.170_172delAGA [p.Lys57del]) and a nonsense mutation (c.1017G>A [p.Trp339(∗)]). The maternal aunt was homozygous for the nonsense mutation (c.1017G>A [p.Trp339(∗)]). Mutational analysis of GNB3 in a cohort of 58 subjects with CSNB identified a sporadic case individual with a homozygous GNB3 mutation (c.200C>T [p.Ser67Phe]). GNB3 encodes the β subunit of G protein heterotrimer (Gαβγ) and is known to modulate ON bipolar cell signaling and cone transducin function in mice. Affected human subjects showed an unusual CSNB phenotype with variable degrees of ON bipolar dysfunction and reduced cone sensitivity. This unique retinal disorder with dual anomaly in visual processing expands our knowledge about retinal signaling.
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225
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Al Oreany AA, Al Hadlaq A, Schatz P. Congenital stationary night blindness with hypoplastic discs, negative electroretinogram and thinning of the inner nuclear layer. Graefes Arch Clin Exp Ophthalmol 2016; 254:1951-1956. [PMID: 27084085 DOI: 10.1007/s00417-016-3346-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/29/2016] [Accepted: 04/05/2016] [Indexed: 10/21/2022] Open
Abstract
PURPOSE To describe congenital stationary night blindness (CSNB) with negative electroretinogram, hypoplastic discs, nystagmus and thinning of the inner nuclear layer (INL). METHODS Retinal structure was analyzed qualitatively with spectral domain optical coherence tomography and wide field imaging. Retinal function was evaluated with full-field electroretinography (ffERG). Molecular genetic testing included next-generation sequencing (NGS) of the known genes involved in CSNB. RESULTS Patients presented with CSNB presented with nystagmus, high myopia, hypoplastic discs and negative ffERG with no measurable rod response. The retinas appeared normal and automated segmentation of retinal layers demonstrated a relative reduction of thickness of the INL. There was no significant change in the ffERG after prolonged 2 hour dark adaptation compared to standard 30 minute dark adaptation. Affected family members harboured the homozygous 1-bp deletion c.2394delC in exon 18 of the TRPM1 gene, whereas their unaffected parents were heterozygous carriers. CONCLUSIONS This data expands the genotype and phenotype spectrum of CSNB. The lack of improvement of rod responses after prolonged dark adaptation, together with thinning of the INL, is compatible with postreceptoral transmission dysfunction in the bipolar cells. Such knowledge may prove useful in future development of treatment for outer retinal dystrophies, using opsin genes to restore light responses in survivor neurons in the inner retina.
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Affiliation(s)
| | - Abdulaziz Al Hadlaq
- Vitreoretinal Division, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
| | - Patrik Schatz
- Vitreoretinal Division, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia. .,Department of Ophthalmology, Clinical Sciences, Scane County University Hospital, University of Lund, Lund, Sweden. .,Executive Medical Department, King Khaled Eye Specialist Hospital, Al-Oruba Street, PO Box 7191, Riyadh, 11462, Saudi Arabia.
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226
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Yung M, Klufas MA, Sarraf D. Clinical applications of fundus autofluorescence in retinal disease. Int J Retina Vitreous 2016; 2:12. [PMID: 27847630 PMCID: PMC5088473 DOI: 10.1186/s40942-016-0035-x] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 02/15/2016] [Indexed: 12/30/2022] Open
Abstract
Fundus autofluorescence (FAF) is a non-invasive retinal imaging modality used in clinical practice to provide a density map of lipofuscin, the predominant ocular fluorophore, in the retinal pigment epithelium. Multiple commercially available imaging systems, including the fundus camera, the confocal scanning laser ophthalmoscope, and the ultra-widefield imaging device, are available to the clinician. Each offers unique advantages for evaluating various retinal diseases. The clinical applications of FAF continue to expand. It is now an essential tool for evaluating age related macular degeneration, macular dystrophies, retinitis pigmentosa, white dot syndromes, retinal drug toxicities, and various other retinal disorders. FAF may detect abnormalities beyond those detected on funduscopic exam, fluorescein angiography, or optical coherence tomography, and can be used to elucidate disease pathogenesis, form genotype-phenotype correlations, diagnose and monitor disease, and evaluate novel therapies. Given its ease of use, non-invasive nature, and value in characterizing retinal disease, FAF enjoys increasing clinical relevance. This review summarizes common ocular fluorophores, imaging modalities, and FAF findings for a wide spectrum of retinal disorders.
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Affiliation(s)
- Madeline Yung
- Stein Eye Institute, David Geffen School of Medicine at University of California, Los Angeles, CA 90095 USA
| | - Michael A. Klufas
- Stein Eye Institute, David Geffen School of Medicine at University of California, Los Angeles, CA 90095 USA
| | - David Sarraf
- Stein Eye Institute, David Geffen School of Medicine at University of California, Los Angeles, CA 90095 USA
- Greater Los Angeles VA Healthcare Center, Los Angeles, CA 90024 USA
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227
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Tanimoto N, Akula JD, Fulton AB, Weber BHF, Seeliger MW. Differentiation of murine models of “negative ERG” by single and repetitive light stimuli. Doc Ophthalmol 2016; 132:101-9. [DOI: 10.1007/s10633-016-9534-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 03/03/2016] [Indexed: 02/03/2023]
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228
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Neuillé M, Malaichamy S, Vadalà M, Michiels C, Condroyer C, Sachidanandam R, Srilekha S, Arokiasamy T, Letexier M, Démontant V, Sahel JA, Sen P, Audo I, Soumittra N, Zeitz C. Next-generation sequencing confirms the implication of SLC24A1 in autosomal-recessive congenital stationary night blindness. Clin Genet 2016; 89:690-9. [PMID: 26822852 DOI: 10.1111/cge.12746] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 01/25/2016] [Accepted: 01/25/2016] [Indexed: 01/17/2023]
Abstract
Congenital stationary night blindness (CSNB) is a clinically and genetically heterogeneous retinal disorder which represents rod photoreceptor dysfunction or signal transmission defect from photoreceptors to adjacent bipolar cells. Patients displaying photoreceptor dysfunction show a Riggs-electroretinogram (ERG) while patients with a signal transmission defect show a Schubert-Bornschein ERG. The latter group is subdivided into complete or incomplete (ic) CSNB. Only few CSNB cases with Riggs-ERG and only one family with a disease-causing variant in SLC24A1 have been reported. Whole-exome sequencing (WES) in a previously diagnosed icCSNB patient identified a homozygous nonsense variant in SLC24A1. Indeed, re-investigation of the clinical data corrected the diagnosis to Riggs-form of CSNB. Targeted next-generation sequencing (NGS) identified compound heterozygous deletions and a homozygous missense variant in SLC24A1 in two other patients, respectively. ERG abnormalities varied in these three cases but all patients had normal visual acuity, no myopia or nystagmus, unlike in Schubert-Bornschein-type of CSNB. This confirms that SLC24A1 defects lead to CSNB and outlines phenotype/genotype correlations in CSNB subtypes. In case of unclear clinical characteristics, NGS techniques are helpful to clarify the diagnosis.
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Affiliation(s)
- M Neuillé
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - S Malaichamy
- SN ONGC Department of Genetics and Molecular Biology, Vision Research Foundation, Chennai, India
| | - M Vadalà
- Ophthalmology Section, Department of Experimental Medicine and Clinical Neuroscience, University of Palermo, Palermo, Italy
| | - C Michiels
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - C Condroyer
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - R Sachidanandam
- Department of Optometry, Medical Research Foundation, Chennai, India
| | - S Srilekha
- SN ONGC Department of Genetics and Molecular Biology, Vision Research Foundation, Chennai, India
| | - T Arokiasamy
- SN ONGC Department of Genetics and Molecular Biology, Vision Research Foundation, Chennai, India
| | | | - V Démontant
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - J-A Sahel
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, Paris, France.,Institute of Ophthalmology, University College of London, London, UK.,Fondation Ophtalmologique Adolphe de Rothschild, Paris, France.,Académie des Sciences, Institut de France, Paris, France
| | - P Sen
- Department of Vitreo-Retinal Services, Medical Research Foundation, Chennai, India
| | - I Audo
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, Paris, France.,Institute of Ophthalmology, University College of London, London, UK
| | - N Soumittra
- SN ONGC Department of Genetics and Molecular Biology, Vision Research Foundation, Chennai, India
| | - C Zeitz
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
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229
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Giblin JP, Comes N, Strauss O, Gasull X. Ion Channels in the Eye: Involvement in Ocular Pathologies. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 104:157-231. [PMID: 27038375 DOI: 10.1016/bs.apcsb.2015.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The eye is the sensory organ of vision. There, the retina transforms photons into electrical signals that are sent to higher brain areas to produce visual sensations. In the light path to the retina, different types of cells and tissues are involved in maintaining the transparency of avascular structures like the cornea or lens, while others, like the retinal pigment epithelium, have a critical role in the maintenance of photoreceptor function by regenerating the visual pigment. Here, we have reviewed the roles of different ion channels expressed in ocular tissues (cornea, conjunctiva and neurons innervating the ocular surface, lens, retina, retinal pigment epithelium, and the inflow and outflow systems of the aqueous humor) that are involved in ocular disease pathophysiologies and those whose deletion or pharmacological modulation leads to specific diseases of the eye. These include pathologies such as retinitis pigmentosa, macular degeneration, achromatopsia, glaucoma, cataracts, dry eye, or keratoconjunctivitis among others. Several disease-associated ion channels are potential targets for pharmacological intervention or other therapeutic approaches, thus highlighting the importance of these channels in ocular physiology and pathophysiology.
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Affiliation(s)
- Jonathan P Giblin
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Nuria Comes
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | | | - Xavier Gasull
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
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230
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Fine I, Boynton GM. Pulse trains to percepts: the challenge of creating a perceptually intelligible world with sight recovery technologies. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140208. [PMID: 26240423 PMCID: PMC4528820 DOI: 10.1098/rstb.2014.0208] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2015] [Indexed: 11/12/2022] Open
Abstract
An extraordinary variety of sight recovery therapies are either about to begin clinical trials, have begun clinical trials, or are currently being implanted in patients. However, as yet we have little insight into the perceptual experience likely to be produced by these implants. This review focuses on methodologies, such as optogenetics, small molecule photoswitches and electrical prostheses, which use artificial stimulation of the retina to elicit percepts. For each of these technologies, the interplay between the stimulating technology and the underlying neurophysiology is likely to result in distortions of the perceptual experience. Here, we describe some of these potential distortions and discuss how they might be minimized either through changes in the encoding model or through cortical plasticity.
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Affiliation(s)
- Ione Fine
- Department of Psychology, University of Washington, Seattle, WA, USA
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231
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Scalabrino ML, Boye SL, Fransen KMH, Noel JM, Dyka FM, Min SH, Ruan Q, De Leeuw CN, Simpson EM, Gregg RG, McCall MA, Peachey NS, Boye SE. Intravitreal delivery of a novel AAV vector targets ON bipolar cells and restores visual function in a mouse model of complete congenital stationary night blindness. Hum Mol Genet 2015; 24:6229-39. [PMID: 26310623 DOI: 10.1093/hmg/ddv341] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 08/17/2015] [Indexed: 11/13/2022] Open
Abstract
Adeno-associated virus (AAV) effectively targets therapeutic genes to photoreceptors, pigment epithelia, Müller glia and ganglion cells of the retina. To date, no one has shown the ability to correct, with gene replacement, an inherent defect in bipolar cells (BCs), the excitatory interneurons of the retina. Targeting BCs with gene replacement has been difficult primarily due to the relative inaccessibility of BCs to standard AAV vectors. This approach would be useful for restoration of vision in patients with complete congenital stationary night blindness (CSNB1), where signaling through the ON BCs is eliminated due to mutations in their G-protein-coupled cascade genes. For example, the majority of CSNB1 patients carry a mutation in nyctalopin (NYX), which encodes a protein essential for proper localization of the TRPM1 cation channel required for ON BC light-evoked depolarization. As a group, CSNB1 patients have a normal electroretinogram (ERG) a-wave, indicative of photoreceptor function, but lack a b-wave due to defects in ON BC signaling. Despite retinal dysfunction, the retinas of CSNB1 patients do not degenerate. The Nyx(nob) mouse model of CSNB1 faithfully mimics this phenotype. Here, we show that intravitreally injected, rationally designed AAV2(quadY-F+T-V) containing a novel 'Ple155' promoter drives either GFP or YFP_Nyx in postnatal Nyx(nob) mice. In treated Nyx(nob) retina, robust and targeted Nyx transgene expression in ON BCs partially restored the ERG b-wave and, at the cellular level, signaling in ON BCs. Our results support the potential for gene delivery to BCs and gene replacement therapy in human CSNB1.
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Affiliation(s)
| | | | | | | | | | | | | | - Charles N De Leeuw
- Centre for Molecular Medicine and Therapeutics at the Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Elizabeth M Simpson
- Centre for Molecular Medicine and Therapeutics at the Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Ronald G Gregg
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, KY 40202, USA
| | - Maureen A McCall
- Department of Ophthalmology and Visual Sciences, Department of Anatomical Sciences and Neurobiology and
| | - Neal S Peachey
- Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA and Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA
| | - Shannon E Boye
- Department of Ophthalmology and, Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, FL 32610, USA,
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232
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Neuillé M, Morgans CW, Cao Y, Orhan E, Michiels C, Sahel JA, Audo I, Duvoisin RM, Martemyanov KA, Zeitz C. LRIT3 is essential to localize TRPM1 to the dendritic tips of depolarizing bipolar cells and may play a role in cone synapse formation. Eur J Neurosci 2015; 42:1966-75. [PMID: 25997951 DOI: 10.1111/ejn.12959] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 04/30/2015] [Accepted: 05/17/2015] [Indexed: 02/06/2023]
Abstract
Mutations in LRIT3 lead to complete congenital stationary night blindness (cCSNB). The exact role of LRIT3 in ON-bipolar cell signaling cascade remains to be elucidated. Recently, we have characterized a novel mouse model lacking Lrit3 [no b-wave 6, (Lrit3(nob6/nob6) )], which displays similar abnormalities to patients with cCSNB with LRIT3 mutations. Here we compare the localization of components of the ON-bipolar cell signaling cascade in wild-type and Lrit3(nob6/nob6) retinal sections by immunofluorescence confocal microscopy. An anti-LRIT3 antibody was generated. Immunofluorescent staining of LRIT3 in wild-type mice revealed a specific punctate labeling in the outer plexiform layer (OPL), which was absent in Lrit3(nob6/nob6) mice. LRIT3 did not co-localize with ribeye or calbindin but co-localized with mGluR6. TRPM1 staining was severely decreased at the dendritic tips of all depolarizing bipolar cells in Lrit3(nob6/nob6) mice. mGluR6, GPR179, RGS7, RGS11 and Gβ5 immunofluorescence was absent at the dendritic tips of cone ON-bipolar cells in Lrit3(nob6/nob6) mice, while it was present at the dendritic tips of rod bipolar cells. Furthermore, peanut agglutinin (PNA) labeling was severely reduced in the OPL in Lrit3(nob6/nob6) mice. This study confirmed the localization of LRIT3 at the dendritic tips of depolarizing bipolar cells in mouse retina and demonstrated the dependence of TRPM1 localization on the presence of LRIT3. As tested components of the ON-bipolar cell signaling cascade and PNA revealed disrupted localization, an additional function of LRIT3 in cone synapse formation is suggested. These results point to a possibly different regulation of the mGluR6 signaling cascade between rod and cone ON-bipolar cells.
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Affiliation(s)
- Marion Neuillé
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France
| | - Catherine W Morgans
- Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, 33458, USA
| | - Elise Orhan
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France
| | - Christelle Michiels
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France
| | - José-Alain Sahel
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.,Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU ViewMaintain, INSERM-DHOS CIC, 1423, Paris, F-75012, France.,Institute of Ophthalmology, University College of London, London, EC1V 9EL, UK.,Fondation Ophtalmologique Adolphe de Rothschild, Paris, F-75019, France.,Académie des Sciences-Institut de France, Paris, F-75006, France
| | - Isabelle Audo
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.,Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU ViewMaintain, INSERM-DHOS CIC, 1423, Paris, F-75012, France.,Institute of Ophthalmology, University College of London, London, EC1V 9EL, UK
| | - Robert M Duvoisin
- Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, 33458, USA
| | - Christina Zeitz
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France
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233
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Schneider FM, Mohr F, Behrendt M, Oberwinkler J. Properties and functions of TRPM1 channels in the dendritic tips of retinal ON-bipolar cells. Eur J Cell Biol 2015; 94:420-7. [PMID: 26111660 DOI: 10.1016/j.ejcb.2015.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
An increase in light intensity induces a depolarization in retinal ON-bipolar cells via a reduced glutamate release from presynaptic photoreceptor cells. The underlying transduction cascade in the dendritic tips of ON-bipolar cells involves mGluR6 glutamate receptors signaling to TRPM1 proteins that are an indispensable part of the transduction channel. Several other proteins are recognized to participate in the transduction machinery. Deficiency in many of these leads to congenital stationary night blindness, because rod bipolar cells, a subgroup of ON-bipolar cells, constitute the main route for sensory information under scotopic conditions. Here, we review the current knowledge about TRPM1 ion channels and how their activity is regulated within the postsynaptic compartment of ON-bipolar cells. The functional properties of TRPM1 channels in the dendritic compartment are not well understood as they differ substantially from those of recombinant TRPM1 channels. Critical evaluation of possible explanations of these discrepancies indicates that some key components of this transduction pathway might still not be known. The continued exploration of this pathway will yield further clinically useful insights.
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Affiliation(s)
- Franziska M Schneider
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, Deutschhausstr. 1-2, D-35037 Marburg, Germany
| | - Florian Mohr
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, Deutschhausstr. 1-2, D-35037 Marburg, Germany
| | - Marc Behrendt
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, Deutschhausstr. 1-2, D-35037 Marburg, Germany
| | - Johannes Oberwinkler
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, Deutschhausstr. 1-2, D-35037 Marburg, Germany.
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234
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Jacobson SG, Cideciyan AV, Aguirre GD, Roman AJ, Sumaroka A, Hauswirth WW, Palczewski K. Improvement in vision: a new goal for treatment of hereditary retinal degenerations. Expert Opin Orphan Drugs 2015; 3:563-575. [PMID: 26246977 PMCID: PMC4487613 DOI: 10.1517/21678707.2015.1030393] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Introduction: Inherited retinal degenerations (IRDs) have long been considered untreatable and incurable. Recently, one form of early-onset autosomal recessive IRD, Leber congenital amaurosis (LCA) caused by mutations in RPE65 (retinal pigment epithelium-specific protein 65 kDa) gene, has responded with some improvement of vision to gene augmentation therapy and oral retinoid administration. This early success now requires refinement of such therapeutics to fully realize the impact of these major scientific and clinical advances. Areas covered: Progress toward human therapy for RPE65-LCA is detailed from the understanding of molecular mechanisms to preclinical proof-of-concept research to clinical trials. Unexpected positive and complicating results in the patients receiving treatment are explained. Logical next steps to advance the clinical value of the therapeutics are suggested. Expert opinion: The first molecularly based early-phase therapies for an IRD are remarkably successful in that vision has improved and adverse events are mainly associated with surgical delivery to the subretinal space. Yet, there are features of the gene augmentation therapeutic response, such as slowed kinetics of night vision, lack of foveal cone function improvement and relentlessly progressive retinal degeneration despite therapy, that still require research attention.
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Affiliation(s)
- Samuel G Jacobson
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | - Artur V Cideciyan
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | - Gustavo D Aguirre
- University of Pennsylvania, School of Veterinary Medicine, Section of Ophthalmology , Philadelphia, PA, USA
| | - Alejandro J Roman
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | - Alexander Sumaroka
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | | | - Krzysztof Palczewski
- Case Western University, School of Medicine, Cleveland Center for Membrane and Structural Biology, Department of Pharmacology , Cleveland, OH, USA
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235
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Knoflach D, Schicker K, Glösmann M, Koschak A. Gain-of-function nature of Cav1.4 L-type calcium channels alters firing properties of mouse retinal ganglion cells. Channels (Austin) 2015; 9:298-306. [PMID: 26274509 PMCID: PMC4826138 DOI: 10.1080/19336950.2015.1078040] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/22/2015] [Accepted: 07/22/2015] [Indexed: 10/25/2022] Open
Abstract
Proper function of Cav1.4 L-type calcium channels is crucial for neurotransmitter release in the retina. Our understanding about how different levels of Cav1.4 channel activity affect retinal function is still limited. In the gain-of-function mouse model Cav1.4-IT we expected a reduction in the photoreceptor dynamic range but still transmission toward retinal ganglion cells. A fraction of Cav1.4-IT ganglion cells responded to light stimulation in multielectrode array recordings from whole-mounted retinas, but showed a significantly delayed response onset. Another significant number of cells showed higher activity in darkness. In addition to structural remodeling observed at the first retinal synapse of Cav1.4-IT mice the functional data suggested a loss of contrast enhancement, a fundamental feature of our visual system. In fact, Cav1.4-IT mouse retinas showed a decline in spatial response and changes in their contrast sensitivity profile. Photoreceptor degeneration was obvious from the nodular structure of cone axons and enlarged pedicles which partly moved toward the outer nuclear layer. Loss of photoreceptors was also expressed as reduced expression of proteins involved in chemical and electrical transmission, as such metabotropic glutamate receptor mGluR6 and the gap junction protein Connexin 36. Such gross changes in retinal structure and function could also explain the diminished visual performance of CSNB2 patients. The expression pattern of the plasma-membrane calcium ATPase 1 which participates in the maintenance of the intracellular calcium homeostasis in photoreceptors was changed in Cav1.4-IT mice. This might be part of a protection mechanism against increased calcium influx, as this is suggested for Cav1.4-IT channels.
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Affiliation(s)
- Dagmar Knoflach
- Medical University Vienna, Center for Physiology and Pharmacology; Department of Neurophysiology and -pharmacology; Vienna, Austria
| | - Klaus Schicker
- Medical University Vienna, Center for Physiology and Pharmacology; Department of Neurophysiology and -pharmacology; Vienna, Austria
| | | | - Alexandra Koschak
- Medical University Vienna, Center for Physiology and Pharmacology; Department of Neurophysiology and -pharmacology; Vienna, Austria
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology; Innsbruck, Austria
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