1
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Chiang HJ, Nishiwaki Y, Chiang WC, Masai I. Male germ cell-associated kinase is required for axoneme formation during ciliogenesis in zebrafish photoreceptors. Dis Model Mech 2024; 17:dmm050618. [PMID: 38813692 DOI: 10.1242/dmm.050618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 05/16/2024] [Indexed: 05/31/2024] Open
Abstract
Vertebrate photoreceptors are highly specialized retinal neurons that have cilium-derived membrane organelles called outer segments, which function as platforms for phototransduction. Male germ cell-associated kinase (MAK) is a cilium-associated serine/threonine kinase, and its genetic mutation causes photoreceptor degeneration in mice and retinitis pigmentosa in humans. However, the role of MAK in photoreceptors is not fully understood. Here, we report that zebrafish mak mutants show rapid photoreceptor degeneration during embryonic development. In mak mutants, both cone and rod photoreceptors completely lacked outer segments and underwent apoptosis. Interestingly, zebrafish mak mutants failed to generate axonemes during photoreceptor ciliogenesis, whereas basal bodies were specified. These data suggest that Mak contributes to axoneme development in zebrafish, in contrast to mouse Mak mutants, which have elongated photoreceptor axonemes. Furthermore, the kinase activity of Mak was found to be critical in ciliary axoneme development and photoreceptor survival. Thus, Mak is required for ciliogenesis and outer segment formation in zebrafish photoreceptors to ensure intracellular protein transport and photoreceptor survival.
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Affiliation(s)
- Hung-Ju Chiang
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Tancha, Okinawa 904-0495, Japan
| | - Yuko Nishiwaki
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Tancha, Okinawa 904-0495, Japan
| | - Wei-Chieh Chiang
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Tancha, Okinawa 904-0495, Japan
| | - Ichiro Masai
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Tancha, Okinawa 904-0495, Japan
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2
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Otsuka Y, Imamura K, Oishi A, Asakawa K, Kondo T, Nakai R, Suga M, Inoue I, Sagara Y, Tsukita K, Teranaka K, Nishimura Y, Watanabe A, Umeyama K, Okushima N, Mitani K, Nagashima H, Kawakami K, Muguruma K, Tsujikawa A, Inoue H. Phototoxicity avoidance is a potential therapeutic approach for retinal dystrophy caused by EYS dysfunction. JCI Insight 2024; 9:e174179. [PMID: 38646933 PMCID: PMC11141876 DOI: 10.1172/jci.insight.174179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 03/06/2024] [Indexed: 04/25/2024] Open
Abstract
Inherited retinal dystrophies (IRDs) are progressive diseases leading to vision loss. Mutation in the eyes shut homolog (EYS) gene is one of the most frequent causes of IRD. However, the mechanism of photoreceptor cell degeneration by mutant EYS has not been fully elucidated. Here, we generated retinal organoids from induced pluripotent stem cells (iPSCs) derived from patients with EYS-associated retinal dystrophy (EYS-RD). In photoreceptor cells of RD organoids, both EYS and G protein-coupled receptor kinase 7 (GRK7), one of the proteins handling phototoxicity, were not in the outer segment, where they are physiologically present. Furthermore, photoreceptor cells in RD organoids were vulnerable to light stimuli, and especially to blue light. Mislocalization of GRK7, which was also observed in eys-knockout zebrafish, was reversed by delivering control EYS into photoreceptor cells of RD organoids. These findings suggest that avoiding phototoxicity would be a potential therapeutic approach for EYS-RD.
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Affiliation(s)
- Yuki Otsuka
- iPSC-based Drug discovery and Development Team, RIKEN BioResource Research Center, Kyoto, Japan
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Keiko Imamura
- iPSC-based Drug discovery and Development Team, RIKEN BioResource Research Center, Kyoto, Japan
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- RIKEN Center for Advanced Intelligence Project (AIP), Kyoto, Japan
| | - Akio Oishi
- Department of Ophthalmology and Visual Sciences, Nagasaki University, Nagasaki, Japan
| | - Kazuhide Asakawa
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Japan
| | - Takayuki Kondo
- iPSC-based Drug discovery and Development Team, RIKEN BioResource Research Center, Kyoto, Japan
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- RIKEN Center for Advanced Intelligence Project (AIP), Kyoto, Japan
| | - Risako Nakai
- iPSC-based Drug discovery and Development Team, RIKEN BioResource Research Center, Kyoto, Japan
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Mika Suga
- iPSC-based Drug discovery and Development Team, RIKEN BioResource Research Center, Kyoto, Japan
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Ikuyo Inoue
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- RIKEN Center for Advanced Intelligence Project (AIP), Kyoto, Japan
| | - Yukako Sagara
- iPSC-based Drug discovery and Development Team, RIKEN BioResource Research Center, Kyoto, Japan
| | - Kayoko Tsukita
- iPSC-based Drug discovery and Development Team, RIKEN BioResource Research Center, Kyoto, Japan
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Kaori Teranaka
- Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yu Nishimura
- Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Akira Watanabe
- Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kazuhiro Umeyama
- Meiji University International Institute for Bio-Resource Research, Kawasaki, Japan
| | - Nanako Okushima
- Division of Systems Medicine and Gene Therapy, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Kohnosuke Mitani
- Division of Systems Medicine and Gene Therapy, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Hiroshi Nagashima
- Meiji University International Institute for Bio-Resource Research, Kawasaki, Japan
| | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Japan
| | - Keiko Muguruma
- Department of iPS Cell Applied Medicine, Graduate School of Medicine, Kansai Medical University, Hirakata, Osaka, Japan
| | - Akitaka Tsujikawa
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Haruhisa Inoue
- iPSC-based Drug discovery and Development Team, RIKEN BioResource Research Center, Kyoto, Japan
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- RIKEN Center for Advanced Intelligence Project (AIP), Kyoto, Japan
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3
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Truong HM, Cruz-Colón KO, Martínez-Márquez JY, Willer JR, Travis AM, Biswas SK, Lo WK, Bolz HJ, Pearring JN. The tectonic complex regulates membrane protein composition in the photoreceptor cilium. Nat Commun 2023; 14:5671. [PMID: 37704658 PMCID: PMC10500017 DOI: 10.1038/s41467-023-41450-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 08/30/2023] [Indexed: 09/15/2023] Open
Abstract
The primary cilium is a signaling organelle with a unique membrane composition maintained by a diffusional barrier residing at the transition zone. Many transition zone proteins, such as the tectonic complex, are linked to preserving ciliary composition but the mechanism remains unknown. To understand tectonic's role, we generate a photoreceptor-specific Tctn1 knockout mouse. Loss of Tctn1 results in the absence of the entire tectonic complex and associated MKS proteins yet has minimal effects on the transition zone structure of rod photoreceptors. We find that the protein composition of the photoreceptor cilium is disrupted as non-resident membrane proteins accumulate in the cilium over time, ultimately resulting in photoreceptor degeneration. We further show that fluorescent rhodopsin moves faster through the transition zone in photoreceptors lacking tectonic, which suggests that the tectonic complex acts as a physical barrier to slow down membrane protein diffusion in the photoreceptor transition zone to ensure proper removal of non-resident membrane proteins.
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Affiliation(s)
- Hanh M Truong
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, USA
| | - Kevin O Cruz-Colón
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | | | - Jason R Willer
- Department of Ophthalmology and Visual Science, University of Michigan, Ann Arbor, MI, USA
| | - Amanda M Travis
- Department of Ophthalmology and Visual Science, University of Michigan, Ann Arbor, MI, USA
| | - Sondip K Biswas
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Woo-Kuen Lo
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Hanno J Bolz
- Senckenberg Centre for Human Genetics, Frankfurt am Main, Germany
- Institute of Human Genetics, University Hospital of Cologne, Cologne, Germany
| | - Jillian N Pearring
- Department of Ophthalmology and Visual Science, University of Michigan, Ann Arbor, MI, USA.
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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4
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Dai C, Ren W, Wei Y, Xie C, Duan S, Li Q, Jiang L, Shi Y. A Novel Pair of Compound Heterozygous Mutation of EYS in a Han Chinese Family with Retinitis Pigmentosa. Genet Test Mol Biomarkers 2023; 27:258-266. [PMID: 37643323 DOI: 10.1089/gtmb.2023.0016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023] Open
Abstract
Background: Retinitis pigmentosa (RP) is a complex inherited and progressive degenerative retinal disease. The eyes shut homolog (EYS) is frequently associated with RP is surprisingly high. Exploring the function of EYS is quite difficult due to the unique gene size and species specificity. Gene therapy may provide a breakthrough to treat this disease. Therefore, exploring and clarifying pathogenic mutations of EYS-associated RP has important guiding significance for clinical treatment. Methods: Clinical and molecular genetic data for EYS-associated RP were retrospectively analyzed. Sanger sequencing was applied to identify novel mutations in these patients. Candidate pathogenic variants were subsequently evaluated using bioinformatic tools. Results: A novel pair of compound heterozygous mutations was identified: a novel stop-gain mutation c.2439C>A (p.C813fsX) and a frameshift deletion mutation c.6714delT (p. P2238fsX) of the EYS gene in the RP family. Both of these mutations were rare or absent in the 1000 Genomes Project, dbSNP, and Genome Aggregation Database (gnomAD). These two mutations would result in a lack of multiple functionally important epidermal growth factor-like and Laminin G-like coding regions in EYS. Conclusions: A novel compound heterozygote of the EYS gene in a Chinese family with an autosomal inheritance pattern of RP was identified. Identifying more pathogenic mutations and expanding the mutation spectrum of the EYS gene will contribute to a more comprehensive understanding of the molecular pathogenesis of RP disease that could be gained in the future. It also could provide an important basis for the diagnosis, clinical management, and genetic counseling of the disease.
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Affiliation(s)
- Chao Dai
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, China
| | - Weiming Ren
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, China
| | - Yao Wei
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, China
| | - Chunbao Xie
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Suyang Duan
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Qi Li
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Lingxi Jiang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, China
| | - Yi Shi
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, China
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
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5
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Hussain HMJ, Wang M, Huang A, Schmidt R, Qian X, Yang P, Marra M, Li Y, Pennesi ME, Chen R. Novel Pathogenic Mutations Identified from Whole-Genome Sequencing in Unsolved Cases of Patients Affected with Inherited Retinal Diseases. Genes (Basel) 2023; 14:447. [PMID: 36833373 PMCID: PMC9956865 DOI: 10.3390/genes14020447] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 02/12/2023] Open
Abstract
Inherited retinal diseases (IRDs) are a diverse set of visual disorders that collectively represent a major cause of early-onset blindness. With the reduction in sequencing costs in recent years, whole-genome sequencing (WGS) is being used more frequently, particularly when targeted gene panels and whole-exome sequencing (WES) fail to detect pathogenic mutations in patients. In this study, we performed mutation screens using WGS for a cohort of 311 IRD patients whose mutations were undetermined. A total of nine putative pathogenic mutations in six IRD patients were identified, including six novel mutations. Among them, four were deep intronic mutations that affected mRNA splicing, while the other five affected protein-coding sequences. Our results suggested that the rate of resolution of unsolved cases via targeted gene panels and WES can be further enhanced with WGS; however, the overall improvement may be limited.
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Affiliation(s)
- Hafiz Muhammad Jafar Hussain
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Meng Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Austin Huang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ryan Schmidt
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Xinye Qian
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Paul Yang
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Molly Marra
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mark E. Pennesi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
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6
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Sato K, Liu Y, Yamashita T, Ohuchi H. The medaka mutant deficient in eyes shut homolog exhibits opsin transport defects and enhanced autophagy in retinal photoreceptors. Cell Tissue Res 2023; 391:249-267. [PMID: 36418571 DOI: 10.1007/s00441-022-03702-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 11/03/2022] [Indexed: 11/27/2022]
Abstract
Eyes shut homolog (EYS) encodes a proteoglycan and the human mutation causes retinitis pigmentosa type 25 (RP25) with progressive retinal degeneration. RP25 most frequently affects autosomal recessive RP patients with many ethnic backgrounds. Although studies using RP models have facilitated the development of therapeutic medications, Eys has been lost in rodent model animals. Here we examined the roles for Eys in the maintenance of photoreceptor structure and function by generating eys-null medaka fish using the CRISPR-Cas9 system. Medaka EYS protein was present near the connecting cilium of wild-type photoreceptors, while it was absent from the eys-/- retina. The mutant larvae exhibited a reduced visual motor response compared with wild-type. In contrast to reported eys-deficient zebrafish at the similar stage, no retinal cell death was detected in the 8-month post-hatching (8-mph) medaka eys mutant. Immunohistochemistry showed a significant reduction in the length of cone outer segments (OSs), retention of OS proteins in the inner segments of photoreceptors, and abnormal filamentous actin network at the base of cone OSs in the mutant retina by 8 mph. Electron microscopy revealed aberrant structure of calyceal processes, numerous vesiculation and lamellar interruptions, and autophagosomes in the eys-mutant cone photoreceptors. In situ hybridization showed an autophagy component gene, gabarap, was ectopically expressed in the eys-null retina. These results suggest eys is required for regeneration of OS, especially of cone photoreceptors, and transport of OS proteins by regulating actin filaments. Enhanced autophagy may delay the progression of retinal degeneration when lacking EYS in the medaka retina.
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Affiliation(s)
- Keita Sato
- Department of Cytology and Histology, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, 700-8558, Japan.
| | - Yang Liu
- Department of Cytology and Histology, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, 700-8558, Japan
| | - Takahiro Yamashita
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Hideyo Ohuchi
- Department of Cytology and Histology, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, 700-8558, Japan.
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7
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Deletion of POMT2 in Zebrafish Causes Degeneration of Photoreceptors. Int J Mol Sci 2022; 23:ijms232314809. [PMID: 36499139 PMCID: PMC9738688 DOI: 10.3390/ijms232314809] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 11/22/2022] [Accepted: 11/24/2022] [Indexed: 12/03/2022] Open
Abstract
Mutations in the extracellular matrix protein eyes shut homolog (EYS) are a common cause of retinitis pigmentosa, a blinding disease characterized by photoreceptor degeneration. EYS binds to matriglycan, a carbohydrate modification on O-mannosyl glycan substitutions of the cell-surface glycoprotein α-dystroglycan. Patients with mutations in enzymes required for the biosynthesis of matriglycan exhibit syndromic retinal atrophy, along with brain malformations and congenital muscular dystrophy. Protein O-mannosyltransferase 2 (POMT2) is an enzyme required for the synthesis of O-mannosyl glycans. To evaluate the roles of O-mannosyl glycans in photoreceptor health, we generated protein O-mannosyltransferase 2 (pomt2) mutant zebrafish by CRISPR. pomt2 mutation resulted in a loss of matriglycan and abolished binding of EYS protein to α-dystroglycan. Mutant zebrafish presented with hydrocephalus and hypoplasia of the cerebellum, as well as muscular dystrophy. EYS protein was enriched near photoreceptor connecting cilia in the wild-type, but its presence and proper localization was significantly reduced in mutant animals. The mutant retina exhibited mis-localization of opsins and increased apoptosis in both rod and cone photoreceptors. Immunofluorescence intensity of G protein subunit alpha transducin 2 (GNAT2) antibody (a general cone marker) and 1D4 antibody (a long double cone marker) in mutant retinas did not differ from wild-type retinas at 1-month post fertilization, but was reduced at 6 months post fertilization, indicating significant cone degeneration. These data suggest that POMT2-mediated O-mannosyl glycosylation is required for EYS protein localization to the connecting cilium region and photoreceptor survival.
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8
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Lu Y, Li W, Li Y, Zhai W, Zhou X, Wu Z, Jiang S, Liu T, Wang H, Hu R, Zhou Y, Zou J, Hu P, Guan G, Xu Q, Canário AVM, Chen L. Population genomics of an icefish reveals mechanisms of glacier-driven adaptive radiation in Antarctic notothenioids. BMC Biol 2022; 20:231. [PMID: 36224580 PMCID: PMC9560024 DOI: 10.1186/s12915-022-01432-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 10/03/2022] [Indexed: 11/30/2022] Open
Abstract
Background Antarctica harbors the bulk of the species diversity of the dominant teleost fish suborder—Notothenioidei. However, the forces that shape their evolution are still under debate. Results We sequenced the genome of an icefish, Chionodraco hamatus, and used population genomics and demographic modelling of sequenced genomes of 52 C. hamatus individuals collected mainly from two East Antarctic regions to investigate the factors driving speciation. Results revealed four icefish populations with clear reproduction separation were established 15 to 50 kya (kilo years ago) during the last glacial maxima (LGM). Selection sweeps in genes involving immune responses, cardiovascular development, and photoperception occurred differentially among the populations and were correlated with population-specific microbial communities and acquisition of distinct morphological features in the icefish taxa. Population and species-specific antifreeze glycoprotein gene expansion and glacial cycle-paced duplication/degeneration of the zona pellucida protein gene families indicated fluctuating thermal environments and periodic influence of glacial cycles on notothenioid divergence. Conclusions We revealed a series of genomic evidence indicating differential adaptation of C. hamatus populations and notothenioid species divergence in the extreme and unique marine environment. We conclude that geographic separation and adaptation to heterogeneous pathogen, oxygen, and light conditions of local habitats, periodically shaped by the glacial cycles, were the key drivers propelling species diversity in Antarctica. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01432-x.
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Affiliation(s)
- Ying Lu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Wenhao Li
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Yalin Li
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Wanying Zhai
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Xuming Zhou
- Institute of Zoology, Chinese Academy of Science, Beijing, China
| | - Zhichao Wu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Shouwen Jiang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Taigang Liu
- International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China.,College of Information Technology, Shanghai Ocean University, Shanghai, China
| | - Huamin Wang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Ruiqin Hu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Yan Zhou
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Jun Zou
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Peng Hu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Guijun Guan
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China.,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China
| | - Qianghua Xu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China. .,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China.
| | - Adelino V M Canário
- International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China. .,Centre of Marine Sciences (CCMAR-CIMAR LA), University of Algarve, Faro, Portugal.
| | - Liangbiao Chen
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education), Shanghai Ocean University, Shanghai, China. .,International Research Center for Marine Biosciences (Ministry of Science and Technology), Shanghai Ocean University, Shanghai, China.
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9
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Lo JE, Cheng CY, Yang CH, Yang CM, Chen YC, Huang YS, Chen PL, Chen TC. Genotypes Influence Clinical Progression in EYS-Associated Retinitis Pigmentosa. Transl Vis Sci Technol 2022; 11:6. [PMID: 35816039 PMCID: PMC9284463 DOI: 10.1167/tvst.11.7.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Purpose The purpose of this study was to investigate the genetic and clinical characteristics of eyes shut homolog (EYS)-associated retinitis pigmentosa (RP). Methods This was a retrospective cross-sectional observational study of 36 patients with EYS-associated autosomal recessive RP (arRP). Results The gene sequencing results revealed that c.6416G>A (p.Cys2139Tyr) and c.7228+1G>A were the two most predominant variants in our cohort and that variants near the C-terminus, which contains alternating laminin and epidermal growth factor (EGF) domains, accounted for the majority of the allele counts (58 of a total of 72) and relative allele frequencies (81%). Over half of the patients presented with pericentral-type RP (n = 19, 60%), which frequently occurred in combination with macular lesions (n = 10, 52%). Patients having both variants within the alternating laminin and EGF domains near the C-terminus had a more severe disease progression (average 0.045 logMAR increase per year) than those having one variant in the N-terminus and the other in the C-terminus (average 0.001 logMAR increase per year). Conclusions Pericentral RP was the major phenotype in patients with EYS-associated arRP. There was also a statistically significant relationship between the location of the variants and the severity of the disease. Translational Relevance This study may aid patients with EYS-associated arRP to predict future vision acuity based on their genetic and clinical features.
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Affiliation(s)
- Jui-En Lo
- School of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chia-Yi Cheng
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
| | - Chang-Hao Yang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.,Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chung-May Yang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.,Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Chieh Chen
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
| | - Yu-Shu Huang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
| | - Pei-Lung Chen
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Medical Genomics and Proteomics, College of Medicine, National Taiwan University, Taipei, Taiwan.,Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Ta-Ching Chen
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.,Center of Frontier Medicine, National Taiwan University Hospital, Taipei, Taiwan
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10
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Zebrafish and inherited photoreceptor disease: Models and insights. Prog Retin Eye Res 2022; 91:101096. [PMID: 35811244 DOI: 10.1016/j.preteyeres.2022.101096] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 06/20/2022] [Accepted: 06/23/2022] [Indexed: 11/21/2022]
Abstract
Photoreceptor dysfunctions and degenerative diseases are significant causes of vision loss in patients, with few effective treatments available. Targeted interventions to prevent or reverse photoreceptor-related vision loss are not possible without a thorough understanding of the underlying mechanism leading to disease, which is exceedingly difficult to accomplish in the human system. Cone diseases are particularly challenging to model, as some popular genetically modifiable model animals are nocturnal with a rod-dominant visual system and cones that have dissimilarities to human cones. As a result, cone diseases, which affect visual acuity, colour perception, and central vision in patients, are generally poorly understood in terms of pathology and mechanism. Zebrafish (Danio rerio) provide the opportunity to model photoreceptor diseases in a diurnal vertebrate with a cone-rich retina which develops many macular degeneration-like pathologies. Zebrafish undergo external development, allowing early-onset retinal diseases to be detected and studied, and many ophthalmic tools are available for zebrafish visual assessment during development and adulthood. There are numerous zebrafish models of photoreceptor disease, spanning the various types of photoreceptor disease (developmental, rod, cone, and mixed photoreceptor diseases) and genetic/molecular cause. In this review, we explore the features of zebrafish that make them uniquely poised to model cone diseases, summarize the established zebrafish models of inherited photoreceptor disease, and discuss how disease in these models compares to the human presentation, where applicable. Further, we highlight the contributions of these zebrafish models to our understanding of photoreceptor biology and disease, and discuss future directions for utilising and investigating these diverse models.
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11
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Fogerty J, Song P, Boyd P, Grabinski SE, Hoang T, Reich A, Cianciolo LT, Blackshaw S, Mumm JS, Hyde DR, Perkins BD. Notch Inhibition Promotes Regeneration and Immunosuppression Supports Cone Survival in a Zebrafish Model of Inherited Retinal Dystrophy. J Neurosci 2022; 42:5144-5158. [PMID: 35672150 PMCID: PMC9236296 DOI: 10.1523/jneurosci.0244-22.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 04/18/2022] [Accepted: 05/13/2022] [Indexed: 12/31/2022] Open
Abstract
Photoreceptor degeneration leads to irreversible vision loss in humans with retinal dystrophies such as retinitis pigmentosa. Whereas photoreceptor loss is permanent in mammals, zebrafish possesses the ability to regenerate retinal neurons and restore visual function. Following acute damage, Müller glia (MG) re-enter the cell cycle and produce multipotent progenitors whose progeny differentiate into mature neurons. Both MG reprogramming and proliferation of retinal progenitor cells require reactive microglia and associated inflammatory signaling. Paradoxically, in zebrafish models of retinal degeneration, photoreceptor death does not induce the MG to reprogram and regenerate lost cells. Here, we used male and female zebrafish cep290 mutants to demonstrate that progressive cone degeneration generates an immune response but does not stimulate MG proliferation. Acute light damage triggered photoreceptor regeneration in cep290 mutants but cones were only restored to prelesion densities. Using irf8 mutant zebrafish, we found that the chronic absence of microglia reduced inflammation and rescued cone degeneration in cep290 mutants. Finally, single-cell RNA-sequencing revealed sustained expression of notch3 in MG of cep290 mutants and inhibition of Notch signaling induced MG to re-enter the cell cycle. Our findings provide new insights on the requirements for MG to proliferate and the potential for immunosuppression to prolong photoreceptor survival.SIGNIFICANCE STATEMENT Inherited retinal degenerations (IRDs) are genetic diseases that lead to the progressive loss of photoreceptors and the permanent loss of vision. Zebrafish can regenerate photoreceptors after acute injury by reprogramming Müller glia (MG) into stem-like cells that produce retinal progenitors, but this regenerative process fails to occur in zebrafish models of IRDs. Here, we show that Notch pathway inhibition can promote photoreceptor regeneration in models of progressive degeneration and that immunosuppression can prevent photoreceptor loss. These results offer insight into the pathways that promote MG-dependent regeneration and the role of inflammation in photoreceptor degeneration.
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Affiliation(s)
- Joseph Fogerty
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Ping Song
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Patrick Boyd
- Department of Biological Sciences, Center for Zebrafish Research, and Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, Indiana 46556
| | - Sarah E Grabinski
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Thanh Hoang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Adrian Reich
- Florida Research and Innovation Center, Lerner Research Institute, Cleveland Clinic, Port St. Lucie, Florida 34987
| | - Lauren T Cianciolo
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Jeff S Mumm
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - David R Hyde
- Department of Biological Sciences, Center for Zebrafish Research, and Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, Indiana 46556
| | - Brian D Perkins
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio 44195
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio 44195
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio 44195
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12
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Rai D, Iwanami M, Takahashi Y, Komuta Y, Aoi N, Umezawa A, Seko Y. Evaluation of photoreceptor-directed fibroblasts derived from retinitis pigmentosa patients with defects in the EYS gene: a possible cost-effective cellular model for mechanism-oriented drug. Stem Cell Res Ther 2022; 13:157. [PMID: 35410372 PMCID: PMC8996485 DOI: 10.1186/s13287-022-02827-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 03/14/2022] [Indexed: 12/15/2022] Open
Abstract
Background The most common gene responsible for autosomal recessive retinitis pigmentosa (RP) is EYS. The manner of decay of genetically defective EYS gene transcripts varies depending on the type of mutation using our cellular model, which consists of induced photoreceptor-directed fibroblasts from EYS-RP patients (EYS-RP cells). However, disease-specific profiles have not been clarified in EYS-RP cells. Herein we investigated comprehensive gene expression patterns and restoration of altered expression by low molecular weight molecules in EYS-RP cells.
Methods Using induced photoreceptor-like cells by CRX, RAX, NeuroD, and OTX2, we employed qRT-PCR and DNA microarray analysis to compare expression levels of disease-related genes in EYS-RP cells. We investigated the effect of antiapoptotic or anti-endoplasmic reticulum (ER) stress/antioxidant reagents on the restoration of altered gene expression. Results Expression levels of phototransduction-related genes (blue opsin, rhodopsin, S-antigen, GNAT1, GNAT2) were lower in EYS-RP cells. CRYGD was extracted by global gene expression analysis, as a downregulated, retina-related and apoptosis-, endoplasmic reticulum (ER) stress- or aging-related gene. Pathway enrichment analysis suggested that “complement and coagulation cascades,” “ECM-receptor interaction” and “PI3K-Akt signaling pathway” could be involved in EYS-RP-associated pathogenesis. Among the matching/overlapping genes involved in those pathways, F2R was suggested as an EYS-RP-associated gene. The downregulation of CRYGD and F2R was completely restored by additional 4-PBA, an inhibitor of ER stress, and partially restored by metformin or NAC. In addition, 4-PBA normalized the expression level of cleaved caspase-3. Conclusions Our cellular model may reflect the ER stress-mediated degenerative retina and serve as a pathogenesis-oriented cost-effective rescue strategy for RP patients. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-022-02827-x.
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Affiliation(s)
- Dilip Rai
- Sensory Functions Section, Research Institute, National Rehabilitation Center for Persons With Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan
| | - Masaki Iwanami
- Department of Ophthalmology, Hospital, National Rehabilitation Center for Persons With Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan.,Iwanami Eye Clinic, 7-1-3, Tsuchihashi, Miyamae-ku Kawasaki, Tokyo, 216-0005, Japan
| | - Yoriko Takahashi
- Bioscience and Healthcare Engineering Division, Mitsui Knowledge Industry Co., Ltd., 2-7-14 Higashi-Nakano, Nakano-ku, Tokyo, 164-8555, Japan
| | - Yukari Komuta
- Sensory Functions Section, Research Institute, National Rehabilitation Center for Persons With Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan.,Division of Bioinformation and Therapeutic Systems, National Defense Medical College, 3 Namiki, Tokorozawa, 359-0042, Japan
| | - Noriyuki Aoi
- Department of Plastic, Oral and Maxillofacial Surgery, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi, Tokyo, 173-8605, Japan.,Miyamasuzaka Clinic, SK Aoyama Bldg. 5F, 1-6-5 Shibuya, Tokyo, 150-0002, Japan
| | - Akihiro Umezawa
- National Center for Child Health and Development, Research Institute, 2-10-1 Okura, Setagaya, 157-8535, Japan
| | - Yuko Seko
- Sensory Functions Section, Research Institute, National Rehabilitation Center for Persons With Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan.
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13
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Perkins BD. Zebrafish models of inherited retinal dystrophies. JOURNAL OF TRANSLATIONAL GENETICS AND GENOMICS 2022; 6:95-110. [PMID: 35693295 PMCID: PMC9186516 DOI: 10.20517/jtgg.2021.47] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Inherited retinal degenerations (IRDs) cause permanent vision impairment or vision loss due to the death of rod and cone photoreceptors. Animal models of IRDs have been instrumental in providing knowledge of the pathological mechanisms that cause photoreceptor death and in developing successful approaches that could slow or prevent vision loss. Zebrafish models of IRDs represent an ideal model system to study IRDs in a cone-rich retina and to test strategies that exploit the natural ability to regenerate damaged neurons. This review highlights those zebrafish mutants and transgenic lines that exhibit adult-onset retinal degeneration and serve as models of retinitis pigmentosa, cone-rod dystrophy, and ciliopathies.
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Affiliation(s)
- Brian D. Perkins
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, OH 44195, USA
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, OH 44195, USA
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA
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14
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Schellens R, de Vrieze E, Graave P, Broekman S, Nagel-Wolfrum K, Peters T, Kremer H, Collin RWJ, van Wijk E. Zebrafish as a Model to Evaluate a CRISPR/Cas9-Based Exon Excision Approach as a Future Treatment Option for EYS-Associated Retinitis Pigmentosa. Int J Mol Sci 2021; 22:ijms22179154. [PMID: 34502064 PMCID: PMC8431288 DOI: 10.3390/ijms22179154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/18/2021] [Accepted: 08/18/2021] [Indexed: 12/26/2022] Open
Abstract
Retinitis pigmentosa (RP) is an inherited retinal disease (IRD) with an overall prevalence of 1 in 4000 individuals. Mutations in EYS (Eyes shut homolog) are among the most frequent causes of non-syndromic autosomal recessively inherited RP and act via a loss-of-function mechanism. In light of the recent successes for other IRDs, we investigated the therapeutic potential of exon skipping for EYS-associated RP. CRISPR/Cas9 was employed to generate zebrafish from which the region encompassing the orthologous exons 37-41 of human EYS (eys exons 40-44) was excised from the genome. The excision of these exons was predicted to maintain the open reading frame and to result in the removal of exactly one Laminin G and two EGF domains. Although the eysΔexon40-44 transcript was found at levels comparable to wild-type eys, and no unwanted off-target modifications were identified within the eys coding sequence after single-molecule sequencing, EysΔexon40-44 protein expression could not be detected. Visual motor response experiments revealed that eysΔexon40-44 larvae were visually impaired and histological analysis revealed a progressive degeneration of the retinal outer nuclear layer in these zebrafish. Altogether, the data obtained in our zebrafish model currently provide no indications for the skipping of EYS exons 37-41 as an effective future treatment strategy for EYS-associated RP.
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Affiliation(s)
- Renske Schellens
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
| | - Erik de Vrieze
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
| | - Pam Graave
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Sanne Broekman
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
| | - Kerstin Nagel-Wolfrum
- Institute for Molecular Physiology, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany;
- Institute for Developmental Biology and Neurobiology, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - Theo Peters
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
| | - Hannie Kremer
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Rob W. J. Collin
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Erwin van Wijk
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
- Correspondence:
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15
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Garcia-Delgado AB, Valdes-Sanchez L, Morillo-Sanchez MJ, Ponte-Zuñiga B, Diaz-Corrales FJ, de la Cerda B. Dissecting the role of EYS in retinal degeneration: clinical and molecular aspects and its implications for future therapy. Orphanet J Rare Dis 2021; 16:222. [PMID: 34001227 PMCID: PMC8127272 DOI: 10.1186/s13023-021-01843-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 04/23/2021] [Indexed: 01/22/2023] Open
Abstract
Mutations in the EYS gene are one of the major causes of autosomal recessive retinitis pigmentosa. EYS-retinopathy presents a severe clinical phenotype, and patients currently have no therapeutic options. The progress in personalised medicine and gene and cell therapies hold promise for treating this degenerative disease. However, lack of understanding and incomplete comprehension of disease's mechanism and the role of EYS in the healthy retina are critical limitations for the translation of current technical advances into real therapeutic possibilities. This review recapitulates the present knowledge about EYS-retinopathies, their clinical presentations and proposed genotype–phenotype correlations. Molecular details of the gene and the protein, mainly based on animal model data, are analysed. The proposed cellular localisation and roles of this large multi-domain protein are detailed. Future therapeutic approaches for EYS-retinopathies are discussed.
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Affiliation(s)
- Ana B Garcia-Delgado
- Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), Avda. Americo Vespucio 24, 41092, Seville, Spain
| | - Lourdes Valdes-Sanchez
- Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), Avda. Americo Vespucio 24, 41092, Seville, Spain
| | | | - Beatriz Ponte-Zuñiga
- Department of Ophthalmology, University Hospital Virgen Macarena, Seville, Spain.,Retics Oftared, Institute of Health Carlos III, Madrid, Spain
| | - Francisco J Diaz-Corrales
- Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), Avda. Americo Vespucio 24, 41092, Seville, Spain.
| | - Berta de la Cerda
- Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), Avda. Americo Vespucio 24, 41092, Seville, Spain
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16
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Exploring ecological specialization in pipefish using genomic, morphometric and ecological evidence. DIVERS DISTRIB 2021. [DOI: 10.1111/ddi.13286] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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17
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Novel compound heterozygous EYS variants may be associated with arRP in a large Chinese pedigree. Biosci Rep 2021; 40:224912. [PMID: 32436957 PMCID: PMC7268256 DOI: 10.1042/bsr20193443] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 04/22/2020] [Accepted: 04/29/2020] [Indexed: 12/11/2022] Open
Abstract
As a genetically heterogeneous ocular dystrophy, gene mutations with autosomal recessive retinitis pigmentosa (arRP) in patients have not been well described. We aimed to detect the disease-causing genes and variants in a Chinese arRP family. In the present study, a large Chinese pedigree consisting of 31 members including a proband and another two patients was recruited; clinical examinations were conducted; next-generation sequencing using a gene panel was used for identifying pathogenic genes, and Sanger sequencing was performed for verification of mutations. Novel compound heterozygous variants c.G2504A (p.C835Y) and c.G6557A (p.G2186E) for the EYS gene were identified, which co-segregated with the clinical RP phenotypes. Sequencing of 100 ethnically matched normal controls didn't found these mutations in EYS. Therefore, our study identified pathogenic variants in EYS that may cause arRP in this Chinese family. This is the first study to reveal the novel mutation in the EYS gene (c.G2504A, p.C835Y), extending its mutation spectrum. Thus, the EYS c.G2504A (p.C835Y) and c.G6557A (p.G2186E) variants may be the disease-causing missense mutations for RP in this large arRP family. These findings should be helpful for molecular diagnosis, genetic counseling and clinical management of arRP disease.
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18
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A hypomorphic variant in EYS detected by genome-wide association study contributes toward retinitis pigmentosa. Commun Biol 2021; 4:140. [PMID: 33514863 PMCID: PMC7846782 DOI: 10.1038/s42003-021-01662-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 01/06/2021] [Indexed: 12/26/2022] Open
Abstract
The genetic basis of Japanese autosomal recessive retinitis pigmentosa (ARRP) remains largely unknown. Herein, we applied a 2-step genome-wide association study (GWAS) in 640 Japanese patients. Meta-GWAS identified three independent peaks at P < 5.0 × 10−8, all within the major ARRP gene EYS. Two of the three were each in linkage disequilibrium with a different low frequency variant (allele frequency < 0.05); a known founder Mendelian mutation (c.4957dupA, p.S1653Kfs*2) and a non-synonymous variant (c.2528 G > A, p.G843E) of unknown significance. mRNA harboring c.2528 G > A failed to restore rhodopsin mislocalization induced by morpholino-mediated knockdown of eys in zebrafish, consistent with the variant being pathogenic. c.2528 G > A solved an additional 7.0% of Japanese ARRP cases. The third peak was in linkage disequilibrium with a common non-synonymous variant (c.7666 A > T, p.S2556C), possibly representing an unreported disease-susceptibility signal. GWAS successfully unraveled genetic causes of a rare monogenic disorder and identified a high frequency variant potentially linked to development of local genome therapeutics. Koji Nishiguchi et al. identify three genetic variants within the EYS gene that are associated with retinitis pigmentosa using a genome-wide association study. They demonstrate that one of these variants (G843E) causes retinal dysfunction in zebrafish, suggesting a causal role for EYS in retinitis pigmentosa.
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19
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Noel NCL, MacDonald IM, Allison WT. Zebrafish Models of Photoreceptor Dysfunction and Degeneration. Biomolecules 2021; 11:78. [PMID: 33435268 PMCID: PMC7828047 DOI: 10.3390/biom11010078] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 01/02/2021] [Accepted: 01/04/2021] [Indexed: 12/15/2022] Open
Abstract
Zebrafish are an instrumental system for the generation of photoreceptor degeneration models, which can be utilized to determine underlying causes of photoreceptor dysfunction and death, and for the analysis of potential therapeutic compounds, as well as the characterization of regenerative responses. We review the wealth of information from existing zebrafish models of photoreceptor disease, specifically as they relate to currently accepted taxonomic classes of human rod and cone disease. We also highlight that rich, detailed information can be derived from studying photoreceptor development, structure, and function, including behavioural assessments and in vivo imaging of zebrafish. Zebrafish models are available for a diversity of photoreceptor diseases, including cone dystrophies, which are challenging to recapitulate in nocturnal mammalian systems. Newly discovered models of photoreceptor disease and drusenoid deposit formation may not only provide important insights into pathogenesis of disease, but also potential therapeutic approaches. Zebrafish have already shown their use in providing pre-clinical data prior to testing genetic therapies in clinical trials, such as antisense oligonucleotide therapy for Usher syndrome.
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Affiliation(s)
- Nicole C. L. Noel
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada; (I.M.M.); (W.T.A.)
| | - Ian M. MacDonald
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada; (I.M.M.); (W.T.A.)
- Department of Ophthalmology and Visual Sciences, University of Alberta, Edmonton, AB T6G 2R7, Canada
| | - W. Ted Allison
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada; (I.M.M.); (W.T.A.)
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB T6G 2M8, Canada
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20
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Takita S, Seko Y. eys +/- ; lrp5 +/- Zebrafish Reveals Lrp5 Can Be the Receptor of Retinol in the Visual Cycle. iScience 2020; 23:101762. [PMID: 33251495 PMCID: PMC7683268 DOI: 10.1016/j.isci.2020.101762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/17/2020] [Accepted: 10/30/2020] [Indexed: 12/04/2022] Open
Abstract
Vision is essential for vertebrates including humans. Sustained vision is accomplished by retinoid metabolism, the “visual cycle,” where all-trans retinol (atROL) is incorporated into the retinal pigment epithelium (RPE) from photoreceptors presumably through decade-long missing receptor(s). Here, we show that the LDL-related receptor-5 (Lrp5) protein is linked to the retinol binding protein 1a (Rbp1a), the transporter of atROL in the visual cycle, by generating and analyzing the digenic eyes shut homolog+/-; lrp5+/− zebrafish, the same form of gene defect detected in a human case of inherited retinal degeneration. Global gene expression analysis followed by genetic study clarified that rbp1a played a role downstream of lrp5. Rbp1a protein was colocalized with Lrp5 protein at microvilli of RPE cells. Furthermore, Rbp1a directly bound to the C-terminal intracellular region of Lrp5 in vitro. Collectively, these results strongly suggest that Lrp5 is a potent candidate of the receptor of atROL in the visual cycle. eys+/-; lrp5+/− zebrafish showed mild photoreceptor degeneration Microarray analysis identified dramatical decrease of rbp1a expression Rbp1a protein was colocalized with Lrp5 protein at the microvilli of the RPE Rbp1a directly bound to the C-terminal intracellular region of Lrp5 in vitro
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Affiliation(s)
- Shimpei Takita
- Visual Functions Section, Department of Rehabilitation for Sensory Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan
| | - Yuko Seko
- Visual Functions Section, Department of Rehabilitation for Sensory Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan
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21
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Song P, Fogerty J, Cianciolo LT, Stupay R, Perkins BD. Cone Photoreceptor Degeneration and Neuroinflammation in the Zebrafish Bardet-Biedl Syndrome 2 ( bbs2) Mutant Does Not Lead to Retinal Regeneration. Front Cell Dev Biol 2020; 8:578528. [PMID: 33324636 PMCID: PMC7726229 DOI: 10.3389/fcell.2020.578528] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/03/2020] [Indexed: 11/17/2022] Open
Abstract
Bardet-Biedl syndrome (BBS) is a heterogeneous and pleiotropic autosomal recessive disorder characterized by obesity, retinal degeneration, polydactyly, renal dysfunction, and mental retardation. BBS results from defects in primary and sensory cilia. Mutations in 21 genes have been linked to BBS and proteins encoded by 8 of these genes form a multiprotein complex termed the BBSome. Mutations in BBS2, a component of the BBSome, result in BBS as well as non-syndromic retinal degeneration in humans and rod degeneration in mice, but the role of BBS2 in cone photoreceptor survival is not clear. We used zebrafish bbs2–/– mutants to better understand how loss of bbs2 leads to photoreceptor degeneration. Zebrafish bbs2–/– mutants exhibited impaired visual function as larvae and adult zebrafish underwent progressive cone photoreceptor degeneration. Cone degeneration was accompanied by increased numbers of activated microglia, indicating an inflammatory response. Zebrafish exhibit a robust ability to regenerate lost photoreceptors following retinal damage, yet cone degeneration and inflammation was insufficient to trigger robust Müller cell proliferation. In contrast, high intensity light damage stimulated Müller cell proliferation and photoreceptor regeneration in both wild-type and bbs2–/– mutants, although the bbs2–/– mutants could only restore cones to pre-damaged densities. In summary, these findings suggest that cone degeneration leads to an inflammatory response in the retina and that BBS2 is necessary for cone survival. The zebrafish bbs2 mutant also represents an ideal model to identify mechanisms that will enhance retinal regeneration in degenerating diseases.
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Affiliation(s)
- Ping Song
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Joseph Fogerty
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Lauren T Cianciolo
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Rachel Stupay
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Brian D Perkins
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, United States.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, United States
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22
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Tian W, Li X, Li Y, Wang L, Yang Y, Sun K, Liu W, Zhou B, Lei B, Zhu X. Identification of Novel EYS Mutations by Targeted Sequencing Analysis. Genet Test Mol Biomarkers 2020; 24:745-753. [PMID: 33058741 DOI: 10.1089/gtmb.2020.0186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Purpose: Retinitis pigmentosa (RP) is an inherited and progressive degenerative retinal disease that often results in severe vision loss and blindness. However, mutations in known RP disease genes account for only 60% of RP cases, indicating that there are additional pathogenic mutations are yet to be identified. We aimed to identify the causative mutations in the eyes shut homolog (EYS) gene in a cohort of Chinese RP and rod-cone dystrophy families. Materials and Methods: Targeted next-generation sequencing was applied to identify novel mutations in these patients. Candidate variants were evaluated using bioinformatics tools. Mutations were confirmed by Sanger sequencing. Results: We identified eight heterozygous mutations in the EYS gene in the four probands, including a novel frameshift deletion mutation, c.8242_8243del (p.L2748fs); a novel insertion mutation, c.5802_5803insT (p.I1935YfsX6); a novel splicing mutation, c.1300-1G>A; two heterozygous stop-gain mutations, c.1750G>T (p.E584X) and c.8805C>A (p.Y2935X); and three novel missense mutations, c.8269G>A (p.V2757I), c.2545C>T (p.R849C) and c.7506C>A (p.S2502R). Only c.8805C>A had been reported previously in RP patients. None of these mutations were present in 1000 control individuals. Conclusions: We identified seven novel mutations in the EYS gene, expanding the mutational specra of EYS in Chinese patients with RP and rod-cone dystrophy.
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Affiliation(s)
- Wanli Tian
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Department of Laboratory Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Xiao Li
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Department of Laboratory Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Ya Li
- People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, Zhengzhou, China
| | - Luyao Wang
- Psychosomatic Medicine Center, Sichuan Academy of Medicine and Sichuan Provincial People's Hospital, Chengdu, China
| | - Yeming Yang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Department of Laboratory Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Kuanxiang Sun
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Department of Laboratory Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Wenjing Liu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Department of Laboratory Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Bo Zhou
- Psychosomatic Medicine Center, Sichuan Academy of Medicine and Sichuan Provincial People's Hospital, Chengdu, China
| | - Bo Lei
- People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, Zhengzhou, China
| | - Xianjun Zhu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, Department of Laboratory Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China.,Department of Ophthalmology, First People's Hospital of Shangqiu, Shangqiu, China
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23
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Zebrafish Crb1, Localizing Uniquely to the Cell Membranes around Cone Photoreceptor Axonemes, Alleviates Light Damage to Photoreceptors and Modulates Cones' Light Responsiveness. J Neurosci 2020; 40:7065-7079. [PMID: 32817065 DOI: 10.1523/jneurosci.0497-20.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 06/26/2020] [Accepted: 07/22/2020] [Indexed: 11/21/2022] Open
Abstract
The crumbs (crb) apical polarity genes are essential for the development and functions of epithelia. Adult zebrafish retinal neuroepithelium expresses three crb genes (crb1, crb2a, and crb2b); however, it is unknown whether and how Crb1 differs from other Crb proteins in expression, localization, and functions. Here, we show that, unlike zebrafish Crb2a and Crb2b as well as mammalian Crb1 and Crb2, zebrafish Crb1 does not localize to the subapical regions of photoreceptors and Müller glial cells; rather, it localizes to a small region of cone outer segments: the cell membranes surrounding the axonemes. Moreover, zebrafish Crb1 is not required for retinal morphogenesis and photoreceptor patterning. Interestingly, Crb1 promotes rod survival under strong white light irradiation in a previously unreported non--cell-autonomous fashion; in addition, Crb1 delays UV and blue cones' chromatin condensation caused by UV light irradiation. Finally, Crb1 plays a role in cones' responsiveness to light through an arrestin-translocation-independent mechanism. The localization of Crb1 and its functions do not differ between male and female fish. We conclude that zebrafish Crb1 has diverged from other vertebrate Crb proteins, representing a neofunctionalization in Crb biology during evolution.SIGNIFICANCE STATEMENT Apicobasal polarity of epithelia is an important property that underlies the morphogenesis and functions of epithelial tissues. Epithelial apicobasal polarity is controlled by many polarity genes, including the crb genes. In vertebrates, multiple crb genes have been identified, but the differences in their expression patterns and functions are not fully understood. Here, we report a novel subcellular localization of zebrafish Crb1 in retinal cone photoreceptors and evidence for its new functions in photoreceptor maintenance and light responsiveness. This study expands our understanding of the biology of the crb genes in epithelia, including retinal neuroepithelium.
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24
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Liu Y, Cao S, Yu M, Hu H. TMEM216 Deletion Causes Mislocalization of Cone Opsin and Rhodopsin and Photoreceptor Degeneration in Zebrafish. Invest Ophthalmol Vis Sci 2020; 61:24. [PMID: 32687549 PMCID: PMC7425700 DOI: 10.1167/iovs.61.8.24] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 06/13/2020] [Indexed: 02/06/2023] Open
Abstract
Purpose Mutations in TMEM216, a ciliary transition zone tetraspan transmembrane protein, are linked to Joubert syndrome and Meckel syndrome. Photoreceptor degeneration is a prominent phenotype in Joubert syndrome. How TMEM216 contributes to photoreceptor health is poorly understood. Methods We have generated tmem216 knockout zebrafish by CRISPR genome editing. The impact of TMEM216 deletion on photoreceptors was evaluated by immunofluorescence staining and electron microscopy. Results Homozygous tmem216 knockout zebrafish died before 21 days after fertilization. Their retina exhibited reduced immunoreactivity to rod photoreceptor outer segment marker 4D2 and cone photoreceptor outer segment marker G protein subunit α transducin 2 (GNAT2). Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) revealed an increase in TUNEL-positive nuclei in the knockout retina, indicating photoreceptor degeneration. The tmem216 mutation resulted in shortened photoreceptor ciliary axoneme, as revealed by acetylated α-tubulin immunostaining. Photoreceptors in knockout zebrafish exhibited mislocalization of outer segment proteins such as rhodopsin, GNAT2, and red opsin to the inner segment and cell bodies. Additionally, electron microscopy revealed that the mutant photoreceptors elaborated outer segment with abnormal disc morphology such as shortened discs and vesicles/vacuoles within the outer segment. Conclusion Our results indicate that TMEM216 is essential for normal genesis of outer segment disc structures, transport of outer segment materials, and survival of photoreceptors in zebrafish. These tmem216 knockout zebrafish will be useful in studying how transition zone proteins regulate photoreceptor outer segment formation and maintenance.
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Affiliation(s)
- Yu Liu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, New York, United States
| | - Shuqin Cao
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, New York, United States
| | - Miao Yu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, New York, United States
| | - Huaiyu Hu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, New York, United States
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25
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Liu Y, Yu M, Shang X, Nguyen MHH, Balakrishnan S, Sager R, Hu H. Eyes shut homolog (EYS) interacts with matriglycan of O-mannosyl glycans whose deficiency results in EYS mislocalization and degeneration of photoreceptors. Sci Rep 2020; 10:7795. [PMID: 32385361 PMCID: PMC7210881 DOI: 10.1038/s41598-020-64752-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 04/21/2020] [Indexed: 12/12/2022] Open
Abstract
Mutations in eyes shut homolog (EYS), a secreted extracellular matrix protein containing multiple laminin globular (LG) domains, and in protein O-mannose β1, 2-N-acetylglucosaminyl transferase 1 (POMGnT1), an enzyme involved in O-mannosyl glycosylation, cause retinitis pigmentosa (RP), RP25 and RP76, respectively. How EYS and POMGnT1 regulate photoreceptor survival is poorly understood. Since some LG domain-containing proteins function by binding to the matriglycan moiety of O-mannosyl glycans, we hypothesized that EYS interacted with matriglycans as well. To test this hypothesis, we performed EYS Far-Western blotting assay and generated pomgnt1 mutant zebrafish. The results showed that EYS bound to matriglycans. Pomgnt1 mutation in zebrafish resulted in a loss of matriglycan, retention of synaptotagmin-1-positive EYS secretory vesicles within the outer nuclear layer, and diminished EYS protein near the connecting cilia. Photoreceptor density in 2-month old pomgnt1 mutant retina was similar to the wild-type animals but was significantly reduced at 6-months. These results indicate that EYS protein localization to the connecting cilia requires interaction with the matriglycan and that O-mannosyl glycosylation is required for photoreceptor survival in zebrafish. This study identified a novel interaction between EYS and matriglycan demonstrating that RP25 and RP76 are mechanistically linked in that O-mannosyl glycosylation controls targeting of EYS protein.
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Affiliation(s)
- Yu Liu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - Miao Yu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - Xuanze Shang
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - My Hong Hoai Nguyen
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
- Department of Biological Sciences, State University of New York at Plattsburgh, 101 Broad St., Plattsburgh, New York, 12901, USA
| | - Shanmuganathan Balakrishnan
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - Rachel Sager
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - Huaiyu Hu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA.
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26
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Carter SP, Moran AL, Matallanas D, McManus GJ, Blacque OE, Kennedy BN. Genetic Deletion of Zebrafish Rab28 Causes Defective Outer Segment Shedding, but Not Retinal Degeneration. Front Cell Dev Biol 2020; 8:136. [PMID: 32258030 PMCID: PMC7092623 DOI: 10.3389/fcell.2020.00136] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 02/18/2020] [Indexed: 01/14/2023] Open
Abstract
The photoreceptor outer segment is the canonical example of a modified and highly specialized cilium, with an expanded membrane surface area in the form of disks or lamellae for efficient light detection. Many ciliary proteins are essential for normal photoreceptor function and cilium dysfunction often results in retinal degeneration leading to impaired vision. Herein, we investigate the function and localization of the ciliary G-protein RAB28 in zebrafish cone photoreceptors. CRISPR-Cas9 generated rab28 mutant zebrafish display significantly reduced shed outer segment material/phagosomes in the RPE at 1 month post fertilization (mpf), but otherwise normal visual function up to 21 dpf and retinal structure up to 12 mpf. Cone photoreceptor-specific transgenic reporter lines show Rab28 localizes almost exclusively to outer segments, independently of GTP/GDP nucleotide binding. Co-immunoprecipitation analysis demonstrates tagged Rab28 interacts with components of the phototransduction cascade, including opsins, phosphodiesterase 6C and guanylate cyclase 2D. Our data shed light on RAB28 function in cones and provide a model for RAB28-associated cone-rod dystrophy.
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Affiliation(s)
- Stephen P Carter
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Ailís L Moran
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - David Matallanas
- Systems Biology Ireland, University College Dublin, Dublin, Ireland
| | - Gavin J McManus
- School of Biochemistry and Immunology, Microscopy Facility, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Oliver E Blacque
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Breandán N Kennedy
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Conway Institute, University College Dublin, Dublin, Ireland
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27
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Sun Y, Li JK, He W, Wang ZS, Bai JY, Xu L, Xing B, Zhang JG, Wang L, Li W, Chen F. Genetic and clinical analysis in Chinese patients with retinitis pigmentosa caused by EYS mutations. Mol Genet Genomic Med 2020; 8:e1117. [PMID: 31944634 PMCID: PMC7057104 DOI: 10.1002/mgg3.1117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 12/15/2019] [Accepted: 12/20/2019] [Indexed: 12/22/2022] Open
Abstract
Background Panel‐based targeted exome sequencing was applied to identify the pathogenic variants and genetic characteristics of retinitis pigmentosa (RP) in two Chinese families, and to gain a deeper understanding of the relationship between clinical manifestations and genotypes. Methods A total of 17 subjects, comprising two probands (total patients: four subjects) and their family member, were recruited in this study. All subjects underwent comprehensive ophthalmic examinations and clinical evaluations, and the complete history and medical records were collected according to the standard procedures. All participants were screened using the multigene panel test (Target_Eye_792_V2 chip), and Sanger sequencing was used to confirm the candidate variants. Results Among these two families, a total of three novel mutations in the EYS gene were identified in patients, including a homozygous frameshift mutation c.9252_9253insT detected in two patients in one family, and the compound heterozygous splicesite mutation c.5644+2T>C and frameshift mutation c.1920_1923delTGAG detected in two patients in the another family. All patients in both families had early onset of night blindness and poor visual acuity, and with typical posterior capsule opacification. The mutation co‐segregated within all recruited individuals. In addition, one patient with compound heterozygous mutations was found to have typical blue‐blindness symptoms and detected a previously reported disease‐causing mutation c.235G>A in OPN1SW gene, which caused blue blindness manifestations and was first discovered in patient combined with RP causative genes. Conclusions Panel‐based targeted exome sequencing was used to identify three novel variants of RP causative gene, and we also detected a known pathogenic variants of blue‐blindness causative genes in two patients. Our finding will provide a powerful basis for genetic counseling and enhance our current understanding of the genetics factors for RP families.
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Affiliation(s)
- Yan Sun
- Shenyang He Eye Specialist Hospital, Shenyang, China.,He University, Shenyang, China
| | - Jian-Kang Li
- Department of Computer Science, City University of Hong Kong, Kowloon, Hong Kong.,BGI-Shenzhen, Shenzhen, China
| | - Wei He
- Shenyang He Eye Specialist Hospital, Shenyang, China.,He University, Shenyang, China
| | - Zhuo-Shi Wang
- Shenyang He Eye Specialist Hospital, Shenyang, China.,He University, Shenyang, China
| | - Jin-Yue Bai
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Ling Xu
- Shenyang He Eye Specialist Hospital, Shenyang, China.,He University, Shenyang, China
| | - Bo Xing
- School of Basic Medicine, Qingdao University, Qingdao, China
| | | | - Lusheng Wang
- Department of Computer Science, City University of Hong Kong, Kowloon, Hong Kong.,BGI-Shenzhen, Shenzhen, China
| | - Wei Li
- He University, Shenyang, China.,BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China
| | - Fang Chen
- BGI-Shenzhen, Shenzhen, China.,Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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28
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Iwanami M, Oishi A, Ogino K, Seko Y, Nishida-Shimizu T, Yoshimura N, Kato S. Five major sequence variants and copy number variants in the EYS gene account for one-third of Japanese patients with autosomal recessive and simplex retinitis pigmentosa. Mol Vis 2019; 25:766-779. [PMID: 31814702 PMCID: PMC6857781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 11/13/2019] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To elucidate the variant spectrum of the EYS gene in a large cohort of Japanese patients with autosomal recessive and simplex retinitis pigmentosa (arRP and sRP). METHODS We performed a direct sequencing analysis of 44 exons of the EYS gene in 469 patients with RP (including 144 arRP, 288 sRP, and 17 autosomal dominant RP (adRP) cases) in eastern and western regions of Japan and a multiplex ligation-dependent probe amplification (MLPA) of patients who had a single heterozygous pathogenic variant. RESULTS We identified six pathogenic and 16 likely pathogenic variants from a total of 186 nucleotide sequence variants, of which five variants, c.2528G>A (p.(Gly843Glu)), c.4957dupA (p.(Ser1653Lysfs*2)), c.6557G>A (p.(Gly2186Glu)), c.6563T>C (p.(Ile2188Thr)), and c.8868C>A (p.(Tyr2956*)), were prevalent in patients with arRP and sRP. The homozygous and heterozygous combinations of these five variants accounted for 32.4% (140/432) of Japanese patients with arRP and sRP. Five patients with adRP also had these variants. These five variants segregated with the phenotype in 15 families with RP. MLPA revealed seven copy number variations (CNVs) of the EYS exon(s). CONCLUSIONS This study showed that five major sequence variants and CNVs in the EYS gene account for one-third of Japanese patients with arRP and sRP, and these variants are also responsible for RP showing an autosomal dominant inheritance pattern. This is the first report showing the pathogenicity of three missense variants (p.(Gly843Glu), p.(Gly2186Glu), and p.(Ile2188Thr)) and the presence of CNVs in the EYS gene of Japanese patients with arRP and sRP.
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Affiliation(s)
- Masaki Iwanami
- Department of Ophthalmology, Hospital, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan
| | - Akio Oishi
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Ken Ogino
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yuko Seko
- Department of Ophthalmology, Hospital, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan,Department of Rehabilitation for Sensory Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan
| | - Tomomi Nishida-Shimizu
- Department of Ophthalmology, Hospital, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan
| | - Nagahisa Yoshimura
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Seishi Kato
- Research Institute, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan
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29
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Pierrache LHM, Messchaert M, Thiadens AAHJ, Haer-Wigman L, de Jong-Hesse Y, van Zelst-Stams WAG, Collin RWJ, Klaver CCW, van den Born LI. Extending the Spectrum of EYS-Associated Retinal Disease to Macular Dystrophy. Invest Ophthalmol Vis Sci 2019; 60:2049-2063. [PMID: 31074760 DOI: 10.1167/iovs.18-25531] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To assess the phenotypic variability and natural course of inherited retinal diseases (IRDs) caused by EYS mutations. Methods Multiethnic cohort study (N = 30) with biallelic EYS variants from a clinical IRD database (retinitis pigmentosa [RP], N = 27; cone-rod dystrophy [CRD], N = 1; and macular dystrophy, N = 2). In vitro minigene splice assay was performed to determine the effect on EYS pre-mRNA splicing of the c.1299+5_1299+8del variant in macular dystrophy patients. Results We found 27 different EYS variants in RP patients and 7 were novel. The rate of visual field loss of the V4e isopter area was -0.84 ± 0.44 ln(deg2) per year, and the rate of visual acuity loss was 0.75 Early Treatment Diabetic Retinopathy Study letters per year. Ellipsoid zone width was correlated with area of the hyperautofluorescent ring, with rs = 0.78 and P < 0.001. Rate of decline in ellipsoid zone width was -57 ± 17 μm per year (P < 0.01) (n = 14) or -3.69% ± 0.51% from baseline per year (P < 0.001). An isolated CRD patient carried a homozygous EYS variant (c.9405T>A), previously identified in RP patients. Two siblings with macular dystrophy carried compound heterozygous EYS variants: c.1299+5_1299+8del and c.6050G>T. The former was novel and shown to result in skipping of exon 8, and the latter was a known RP variant. Conclusions We report on EYS-associated macular dystrophy, extending the spectrum of EYS-associated IRDs. We observed heterogeneity between RP patients in age of onset and disease progression. Identical EYS variants were found in cases with RP, CRD, and macular dystrophy. Screening for EYS variants in CRD and macular dystrophy patients might increase the diagnostic yield in previously unsolved cases.
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Affiliation(s)
- Laurence H M Pierrache
- The Rotterdam Eye Hospital, Rotterdam, The Netherlands.,Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands.,Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Muriël Messchaert
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Lonneke Haer-Wigman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Yvonne de Jong-Hesse
- Department of Ophthalmology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | | | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - L Ingeborgh van den Born
- The Rotterdam Eye Hospital, Rotterdam, The Netherlands.,Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands
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30
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Blond F, Léveillard T. Functional Genomics of the Retina to Elucidate its Construction and Deconstruction. Int J Mol Sci 2019; 20:E4922. [PMID: 31590277 PMCID: PMC6801968 DOI: 10.3390/ijms20194922] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 10/01/2019] [Indexed: 12/20/2022] Open
Abstract
The retina is the light sensitive part of the eye and nervous tissue that have been used extensively to characterize the function of the central nervous system. The retina has a central position both in fundamental biology and in the physiopathology of neurodegenerative diseases. We address the contribution of functional genomics to the understanding of retinal biology by reviewing key events in their historical perspective as an introduction to major findings that were obtained through the study of the retina using genomics, transcriptomics and proteomics. We illustrate our purpose by showing that most of the genes of interest for retinal development and those involved in inherited retinal degenerations have a restricted expression to the retina and most particularly to photoreceptors cells. We show that the exponential growth of data generated by functional genomics is a future challenge not only in terms of storage but also in terms of accessibility to the scientific community of retinal biologists in the future. Finally, we emphasize on novel perspectives that emerge from the development of redox-proteomics, the new frontier in retinal biology.
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Affiliation(s)
- Frédéric Blond
- Department of Genetics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
| | - Thierry Léveillard
- Department of Genetics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
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31
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Abstract
Rods and cones are retinal photoreceptor neurons required for our visual sensation. Because of their highly polarized structures and well-characterized processes of G protein-coupled receptor-mediated phototransduction signaling, these photoreceptors have been excellent models for studying the compartmentalization and sorting of proteins. Rods and cones have a modified ciliary compartment called the outer segment (OS) as well as non-OS compartments. The distinct membrane protein compositions between OS and non-OS compartments suggest that the OS is separated from the rest of the cellular compartments by multiple barriers or gates that are selectively permissive to specific cargoes. This review discusses the mechanisms of protein sorting and compartmentalization in photoreceptor neurons. Proper sorting and compartmentalization of membrane proteins are required for signal transduction and transmission. This review also discusses the roles of compartmentalized signaling, which is compromised in various retinal ciliopathies.
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Affiliation(s)
- Yoshikazu Imanishi
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA;
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32
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Takita S, Miyamoto-Matsui K, Seko Y. Intra- and interspecies comparison of EYS transcripts highlights its characteristics in the eye. FASEB J 2019; 33:9422-9433. [PMID: 31120796 DOI: 10.1096/fj.201900056rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Inherited mutations in the eyes shut homolog (EYS) gene cause retinitis pigmentosa. Although knock out of eys in zebrafish is pathogenic, the molecular function of EYS in vertebrate photoreceptors is poorly understood. Here, we show that the 5' portion of EYS is eye-specific across vertebrates. We previously determined that a 3' fragment of EYS with an unknown transcription start site is expressed in human dermal fibroblasts (HDF). To obtain insights into the molecular function of EYS in vertebrate photoreceptors, we extensively analyzed EYS (eys) expression in the human fibroblast cell line HDF-adult (HDF-a), the Y79 retinoblastoma cell line, and in zebrafish eyes using rapid amplification of cDNA end, cap analysis of gene expression, RNA sequencing, and RT-PCR. In HDF-a cells, we identified a novel transcript variant (tv), tv5, transcribed from exon 37. In Y79 cells and zebrafish eyes, EYS (eys) was predominantly transcribed from exon 1 or 2, whereas it was transcribed exclusively from exon 37 in HDF-a cells. In the zebrafish eye, there were splice variants that introduced stop codons, resulting in complete loss of the 3' portion of the RNA. These comparative approaches indicate that the 5' portion of the EYS (eys) mRNA appears to be photoreceptor-specific and that the compositions of the deduced EYS proteins in the eye are well-conserved across vertebrates.-Takita, S., Miyamoto-Matsui, K., Seko, Y. Intra- and interspecies comparison of EYS transcripts highlights its characteristics in the eye.
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Affiliation(s)
- Shimpei Takita
- Visual Functions Section, Department of Rehabilitation for Sensory Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan
| | - Kiyoko Miyamoto-Matsui
- Visual Functions Section, Department of Rehabilitation for Sensory Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan
| | - Yuko Seko
- Visual Functions Section, Department of Rehabilitation for Sensory Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan
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33
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Hohenester E. Laminin G-like domains: dystroglycan-specific lectins. Curr Opin Struct Biol 2018; 56:56-63. [PMID: 30530204 DOI: 10.1016/j.sbi.2018.11.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 11/23/2018] [Accepted: 11/23/2018] [Indexed: 01/31/2023]
Abstract
A unique O-mannose-linked glycan on the transmembrane protein dystroglycan binds a number of extracellular matrix proteins containing laminin G-like (LG) domains. The dystroglycan-matrix interaction is essential for muscle function: disrupted biosynthesis of the matrix-binding modification causes several forms of muscular dystrophy. The complete chemical structure of this modification has been deciphered in the past few years. We now know that LG domains bind to a glycosaminoglycan-like polysaccharide of [-3GlcAβ1,3Xylα1-] units, termed matriglycan, that is attached to a highly unusual heptasaccharide linker. X-ray crystallography has revealed the principles of Ca2+-dependent matriglycan binding by LG domains. In this review, the new structural insights are applied to the growing number of LG domain-containing proteins that bind dystroglycan. It is proposed that LG domains be recognised as 'D-type' lectins to indicate their conserved function in dystroglycan binding.
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Affiliation(s)
- Erhard Hohenester
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom.
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34
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Gaspar P, Almudi I, Nunes MDS, McGregor AP. Human eye conditions: insights from the fly eye. Hum Genet 2018; 138:973-991. [PMID: 30386938 DOI: 10.1007/s00439-018-1948-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 10/20/2018] [Indexed: 12/22/2022]
Abstract
The fruit fly Drosophila melanogaster has served as an excellent model to study and understand the genetics of many human diseases from cancer to neurodegeneration. Studying the regulation of growth, determination and differentiation of the compound eyes of this fly, in particular, have provided key insights into a wide range of diseases. Here we review the regulation of the development of fly eyes in light of shared aspects with human eye development. We also show how understanding conserved regulatory pathways in eye development together with the application of tools for genetic screening and functional analyses makes Drosophila a powerful model to diagnose and characterize the genetics underlying many human eye conditions, such as aniridia and retinitis pigmentosa. This further emphasizes the importance and vast potential of basic research to underpin applied research including identifying and treating the genetic basis of human diseases.
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Affiliation(s)
- Pedro Gaspar
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Isabel Almudi
- Centro Andaluz de Biología del Desarrollo, CSIC/ Universidad Pablo de Olavide, Carretera de Utrera Km1, 41013, Sevilla, Spain
| | - Maria D S Nunes
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Alistair P McGregor
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK.
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35
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Seko Y, Iwanami M, Miyamoto-Matsui K, Takita S, Aoi N, Umezawa A, Kato S. The manner of decay of genetically defective EYS gene transcripts in photoreceptor-directed fibroblasts derived from retinitis pigmentosa patients depends on the type of mutation. Stem Cell Res Ther 2018; 9:279. [PMID: 30359287 PMCID: PMC6202841 DOI: 10.1186/s13287-018-1016-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/11/2018] [Accepted: 09/24/2018] [Indexed: 12/19/2022] Open
Abstract
Background Generation of induced photoreceptors holds promise for in vitro modeling of intractable retinal diseases. Retinitis pigmentosa is an inherited retinal dystrophy that leads to visual impairment. The EYS gene was reported to be the most common gene responsible for autosomal recessive retinitis pigmentosa (arRP). arRP with defects in the EYS gene is denoted by “EYS-RP”. We previously established a “redirect differentiation” method to generate photosensitive photoreceptor-like cells from commercially available human dermal fibroblasts. In this study, we produced photoreceptor-like cells from dermal fibroblasts of EYS-RP patients as a replacement for the degenerative retinas using “redirect differentiation”. We analyzed defective transcripts of the EYS gene in these cells to elucidate phenotypes of EYS-RP patients because decay of transcripts was previously suggested to be involved in phenotypic variation associated with diseases. Methods Using “redirect differentiation” by CRX, RAX, NeuroD and OTX2, we made photoreceptor-directed fibroblasts derived from three normal volunteers and three EYS-RP patients with homozygous or heterozygous mutations. We tested inducible expression of the photoreceptor-specific genes (blue opsin, rhodopsin, recoverin, S-antigen, PDE6C) in these cells. We then analyzed transcripts derived from three different types of the defective EYS gene, c.1211dupA, c.4957dupA and c.8805C > A, expressed in these cells by RT-PCR and sequencing. Results Photoreceptor-specific genes including the EYS gene were up-regulated in all the photoreceptor-directed fibroblasts tested. However, expression levels of defective transcripts were markedly different depending on the type of mutation. Transcripts derived from these three defective genes were scarcely detected, expressed at a lower level, and expressed at almost the same level as in normal volunteers, respectively. Conclusions Expression levels of genetically defective EYS gene transcripts in photoreceptor-directed fibroblasts of EYS-RP patients vary depending on the type of mutation. Variation in expression levels in transcripts having c.1211dupA, c.4957dupA and c.8805C > A suggests that almost complete nonsense-mediated mRNA decay (NMD), partial NMD and escape from NMD occurred for these transcripts, respectively. To determine the relationship with phenotypic variations in EYS-RP patients, more samples are needed. The present study also suggests that the redirect differentiation method could be a valuable tool for disease modeling despite some limitations. Electronic supplementary material The online version of this article (10.1186/s13287-018-1016-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yuko Seko
- Sensory Functions Section, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan. .,Department of Ophthalmology, Hospital, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan.
| | - Masaki Iwanami
- Department of Ophthalmology, Hospital, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan.,Present Address: Iwanami Eye Clinic, 7-1-3, Tsuchihashi, Miyamae-ku Kawasaki-shi, Kanagawa, 216-0005, Japan
| | - Kiyoko Miyamoto-Matsui
- Sensory Functions Section, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan
| | - Shimpei Takita
- Sensory Functions Section, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan
| | - Noriyuki Aoi
- Department of Plastic, Oral and Maxillofacial Surgery, Teikyo University School of Medicine, 2-11-1 Kaga Itabashi-ku, Itabashi, 173-8605, Japan
| | - Akihiro Umezawa
- Department of Reproductive Biology, Center for Regenerative Medicine, National Institute for Child Health and Development, 2-10-1 Okura, Setagaya, 157-8535, Japan
| | - Seishi Kato
- Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan
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36
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Mahato S, Nie J, Plachetzki DC, Zelhof AC. A mosaic of independent innovations involving eyes shut are critical for the evolutionary transition from fused to open rhabdoms. Dev Biol 2018; 443:188-202. [PMID: 30243673 DOI: 10.1016/j.ydbio.2018.09.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 09/18/2018] [Accepted: 09/18/2018] [Indexed: 12/15/2022]
Abstract
A fundamental question in evolutionary biology is how developmental processes are modified to produce morphological innovations while abiding by functional constraints. Here we address this question by investigating the cellular mechanism responsible for the transition between fused and open rhabdoms in ommatidia of apposition compound eyes; a critical step required for the development of visual systems based on neural superposition. Utilizing Drosophila and Tribolium as representatives of fused and open rhabdom morphology in holometabolous insects respectively, we identified three changes required for this innovation to occur. First, the expression pattern of the extracellular matrix protein Eyes Shut (EYS) was co-opted and expanded from mechanosensory neurons to photoreceptor cells in taxa with open rhabdoms. Second, EYS homologs obtained a novel extension of the amino terminus leading to the internalization of a cleaved signal sequence. This amino terminus extension does not interfere with cleavage or function in mechanosensory neurons, but it does permit specific targeting of the EYS protein to the apical photoreceptor membrane. Finally, a specific interaction evolved between EYS and a subset of Prominin homologs that is required for the development of open, but not fused, rhabdoms. Together, our findings portray a case study wherein the evolution of a set of molecular novelties has precipitated the origin of an adaptive photoreceptor cell arrangement.
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Affiliation(s)
- Simpla Mahato
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Jing Nie
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - David C Plachetzki
- Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA.
| | - Andrew C Zelhof
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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37
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Mucciolo DP, Sodi A, Passerini I, Murro V, Cipollini F, Borg I, Pelo E, Contini E, Virgili G, Rizzo S. Fundus phenotype in retinitis pigmentosa associated with EYS mutations. Ophthalmic Genet 2018; 39:589-602. [PMID: 30153090 DOI: 10.1080/13816810.2018.1509351] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
PURPOSE to report phenotypic and genotypic features in a group of autosomal recessive retinitis pigmentosa (arRP) patients associated with EYS mutations. METHODS we retrospectively reviewed the clinical records and the molecular genetic data of arRP patients carrying mutations in the EYS gene. All the patients underwent a comprehensive opthalmological examination. Additional investigation included color fundus photography, fundus autofluorescence, Goldmann visual field, OCT scans and full-field standard electroretinography. RESULTS we studied 10 RP patients (20 eyes) characterized by mutations in the EYS gene. Thirteen different sequence variants in the EYS gene were identified. In total, nine mutations found in our series had not previously been reported in the literature. All patients in our series complained of typical RP symptoms at the onset of the disease, namely night blindness and progressive constriction of the visual field. Visual acuity ranged from light perception to 20/20. Relevant findings reported in our series are Interdigitation-zone (IZ band) involvement, present even in the milder phenotypes and an estimated prevalence of 6.2% of arRP associated with EYS mutations. CONCLUSIONS we reported the mutation spectrum of a group of EYS-related RP patients including nine novel mutations and the associated clinical phenotypes. Our series is the largest group of EYS-related arRP patients in the Italian population.
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Affiliation(s)
- Dario Pasquale Mucciolo
- a Department of Surgery and Translational Medicine , Eye Clinic, University of Florence , Florence , Italy
| | - Andrea Sodi
- a Department of Surgery and Translational Medicine , Eye Clinic, University of Florence , Florence , Italy
| | - Ilaria Passerini
- b Department of Genetic Diagnosis , Careggi Teaching Hospital , Florence , Italy
| | - Vittoria Murro
- a Department of Surgery and Translational Medicine , Eye Clinic, University of Florence , Florence , Italy
| | - Francesca Cipollini
- a Department of Surgery and Translational Medicine , Eye Clinic, University of Florence , Florence , Italy
| | - Isabella Borg
- c Medical Genetics Unit, Department of Pathology , Mater Dei Hospital , Malta.,d Department of Pathology, Faculty of Medicine and Surgery , University of Malta , Malta
| | - Elisabetta Pelo
- b Department of Genetic Diagnosis , Careggi Teaching Hospital , Florence , Italy
| | - Elisa Contini
- b Department of Genetic Diagnosis , Careggi Teaching Hospital , Florence , Italy
| | - Gianni Virgili
- a Department of Surgery and Translational Medicine , Eye Clinic, University of Florence , Florence , Italy
| | - Stanislao Rizzo
- a Department of Surgery and Translational Medicine , Eye Clinic, University of Florence , Florence , Italy
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38
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Messchaert M, Dona M, Broekman S, Peters TA, Corral-Serrano JC, Slijkerman RWN, van Wijk E, Collin RWJ. Eyes shut homolog is important for the maintenance of photoreceptor morphology and visual function in zebrafish. PLoS One 2018; 13:e0200789. [PMID: 30052645 PMCID: PMC6063403 DOI: 10.1371/journal.pone.0200789] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 07/03/2018] [Indexed: 12/27/2022] Open
Abstract
Mutations in eyes shut homolog (EYS), a gene predominantly expressed in the photoreceptor cells of the retina, are among the most frequent causes of autosomal recessive (ar) retinitis pigmentosa (RP), a progressive retinal disorder. Due to the absence of EYS in several rodent species and its retina-specific expression, still little is known about the exact function of EYS and the pathogenic mechanism underlying EYS-associated RP. We characterized eys in zebrafish, by RT-PCR analysis on zebrafish eye-derived RNA, which led to the identification of a 8,715 nucleotide coding sequence that is divided over 46 exons. The transcript is predicted to encode a 2,905-aa protein that contains 39 EGF-like domains and five laminin A G-like domains, which overall shows 33% identity with human EYS. To study the function of EYS, we generated a stable eysrmc101/rmc101 mutant zebrafish model using CRISPR/Cas9 technology. The introduced lesion is predicted to result in premature termination of protein synthesis and lead to loss of Eys function. Immunohistochemistry on retinal sections revealed that Eys localizes at the region of the connecting cilium and that both rhodopsin and cone transducin are mislocalized in the absence of Eys. Electroretinogram recordings showed diminished b-wave amplitudes in eysrmc101/rmc101 zebrafish (5 dpf) compared to age- and strain-matched wild-type larvae. In addition, decreased locomotor activity in response to light stimuli was observed in eys mutant larvae. Altogether, our study shows that absence of Eys leads to a disorganized retinal architecture and causes visual dysfunction in zebrafish.
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Affiliation(s)
- Muriël Messchaert
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Margo Dona
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Sanne Broekman
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Theo A. Peters
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Julio C. Corral-Serrano
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ralph W. N. Slijkerman
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Erwin van Wijk
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rob W. J. Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
- * E-mail:
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39
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C2orf71a/pcare1 is important for photoreceptor outer segment morphogenesis and visual function in zebrafish. Sci Rep 2018; 8:9675. [PMID: 29946172 PMCID: PMC6018674 DOI: 10.1038/s41598-018-27928-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/17/2018] [Indexed: 02/03/2023] Open
Abstract
Mutations in C2orf71 are causative for autosomal recessive retinitis pigmentosa and occasionally cone-rod dystrophy. We have recently discovered that the protein encoded by this gene is important for modulation of the ciliary membrane through the recruitment of an actin assembly module, and have therefore renamed the gene to PCARE (photoreceptor cilium actin regulator). Here, we report on the identification of two copies of the c2orf71/pcare gene in zebrafish, pcare1 and pcare2. To study the role of the gene most similar to human PCARE, pcare1, we have generated a stable pcare1 mutant zebrafish model (designated pcare1rmc100/rmc100) in which the coding sequence was disrupted using CRISPR/Cas9 technology. Retinas of both embryonic (5 dpf) and adult (6 mpf) pcare1rmc100/rmc100 zebrafish display a clear disorganization of photoreceptor outer segments, resembling the phenotype observed in Pcare−/− mice. Optokinetic response and visual motor response measurements indicated visual impairment in pcare1rmc100/rmc100 zebrafish larvae at 5 dpf. In addition, electroretinogram measurements showed decreased b-wave amplitudes in pcare1rmc100/rmc100 zebrafish as compared to age- and strain-matched wild-type larvae, indicating a defect in the transretinal current. Altogether, our data show that lack of pcare1 causes a retinal phenotype in zebrafish and indicate that the function of the PCARE gene is conserved across species.
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40
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Messchaert M, Haer-Wigman L, Khan MI, Cremers FPM, Collin RWJ. EYS mutation update: In silico assessment of 271 reported and 26 novel variants in patients with retinitis pigmentosa. Hum Mutat 2017; 39:177-186. [PMID: 29159838 DOI: 10.1002/humu.23371] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/07/2017] [Accepted: 11/12/2017] [Indexed: 01/22/2023]
Abstract
Mutations in Eyes shut homolog (EYS) are one of the most common causes of autosomal recessive (ar) retinitis pigmentosa (RP), a progressive blinding disorder. The exact function of the EYS protein and the pathogenic mechanisms underlying EYS-associated RP are still poorly understood, which hampers the interpretation of the causality of many EYS variants discovered to date. We collected all reported EYS variants present in 377 arRP index cases published before June 2017, and uploaded them in the Leiden Open Variation Database (www.LOVD.nl/EYS). We also describe 36 additional index cases, carrying 26 novel variants. Of the 297 unique EYS variants identified, almost half (n = 130) are predicted to result in premature truncation of the EYS protein. Classification of all variants using the American College of Medical Genetics and Genomics guidelines revealed that the predicted pathogenicity of these variants cover the complete spectrum ranging from likely benign to pathogenic, although especially missense variants largely fall in the category of uncertain significance. Besides the identification of likely benign alleles previously reported as being probably pathogenic, our comprehensive analysis underscores the need of functional assays to assess the causality of EYS variants, in order to improve molecular diagnostics and counseling of patients with EYS-associated RP.
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Affiliation(s)
- Muriël Messchaert
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lonneke Haer-Wigman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Muhammad I Khan
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
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41
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EYS Mutations Causing Autosomal Recessive Retinitis Pigmentosa: Changes of Retinal Structure and Function with Disease Progression. Genes (Basel) 2017; 8:genes8070178. [PMID: 28704921 PMCID: PMC5541311 DOI: 10.3390/genes8070178] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 07/06/2017] [Accepted: 07/06/2017] [Indexed: 11/24/2022] Open
Abstract
Mutations in the EYS (eyes shut homolog) gene are a common cause of autosomal recessive (ar) retinitis pigmentosa (RP). Without a mammalian model of human EYS disease, there is limited understanding of details of disease expression and rates of progression of the retinal degeneration. We studied clinically and with chromatic static perimetry, spectral-domain optical coherence tomography (OCT), and en face autofluoresence imaging, a cohort of 15 patients (ages 12–51 at first visit), some of whom had longitudinal data of function and structure. Rod sensitivity was able to be measured by chromatic perimetry in most patients at their earliest visits and some patients retained patchy rod function into the fifth decade of life. As expected from RP, cone sensitivity persisted after rod function was no longer measurable. The photoreceptor nuclear layer of the central retina was abnormal except at the fovea in most patients at first visit. Perifoveal disease measured over a period of years indicated that photoreceptor structural loss was followed by dysmorphology of the inner retina and loss of retinal pigment epithelial integrity. Although there could be variability in severity, preliminary analyses of the rates of vision loss suggested that EYS is a more rapidly progressive disease than other ciliopathies causing arRP, such as USH2A and MAK.
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42
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Ablation of EYS in zebrafish causes mislocalisation of outer segment proteins, F-actin disruption and cone-rod dystrophy. Sci Rep 2017; 7:46098. [PMID: 28378834 PMCID: PMC5380955 DOI: 10.1038/srep46098] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 03/10/2017] [Indexed: 01/08/2023] Open
Abstract
Mutations in EYS are associated with autosomal recessive retinitis pigmentosa (arRP) and autosomal recessive cone-rod dystrophy (arCRD) however, the function of EYS and the molecular mechanisms of how these mutations cause retinal degeneration are still unclear. Because EYS is absent in mouse and rat, and the structure of the retina differs substantially between humans and Drosophila, we utilised zebrafish as a model organism to study the function of EYS in the retina. We constructed an EYS-knockout zebrafish-line by TALEN technology which showed visual impairment at an early age, while the histological and immunofluorescence assays indicated the presence of progressive retinal degeneration with a cone predominately affected pattern. These phenotypes recapitulate the clinical manifestations of arCRD patients. Furthermore, the EYS-/- zebrafish also showed mislocalisation of certain outer segment proteins (rhodopsin, opn1lw, opn1sw1, GNB3 and PRPH2), and disruption of actin filaments in photoreceptors. Protein mislocalisation may, therefore, disrupt the function of cones and rods in these zebrafish and cause photoreceptor death. Collectively, these results point to a novel role for EYS in maintaining the morphological structure of F-actin and in protein transport, loss of this function might be the trigger for the resultant cellular events that ultimately lead to photoreceptor death.
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