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Salzman MM, Takimoto T, Foster ML, Mowat FM. Differential gene expression between central and peripheral retinal regions in dogs and comparison with humans. Exp Eye Res 2024; 245:109980. [PMID: 38914302 PMCID: PMC11250724 DOI: 10.1016/j.exer.2024.109980] [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: 02/12/2024] [Revised: 06/09/2024] [Accepted: 06/20/2024] [Indexed: 06/26/2024]
Abstract
The dog retina contains a central macula-like region, and there are reports of central retinal disorders in dogs with shared genetic etiologies with humans. Defining central/peripheral gene expression profiles may provide insight into the suitability of dogs as models for human disorders. We determined central/peripheral posterior eye gene expression profiles in dogs and interrogated inherited retinal and macular disease-associated genes for differential expression between central and peripheral regions. Bulk tissue RNA sequencing was performed on 8 mm samples of the dog central and superior peripheral regions, sampling retina and retinal pigmented epithelium/choroid separately. Reads were mapped to CanFam3.1, read counts were analyzed to determine significantly differentially expressed genes (DEGs). A similar analytic pipeline was used with a published bulk-tissue RNA sequencing human dataset. Pathways and processes involved in significantly DEGs were identified (Database for Annotation, Visualization and Integrated Discovery). Dogs and humans shared the extent and direction of central retinal differential gene expression, with multiple shared biological pathways implicated in differential expression. Many genes implicated in heritable retinal disorders in dogs and humans were differentially expressed between central and periphery. Approximately half of genes associated with human age-related macular degeneration were differentially expressed in human and dog tissues. We have identified similarities and differences in central/peripheral gene expression profiles between dogs and humans which can be applied to further define the relevance of dogs as models for human retinal disorders.
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Affiliation(s)
- Michele M Salzman
- Dept. Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, USA
| | - Tetsuya Takimoto
- Medical Genetics, School of Medicine and Public Health, University of Wisconsin-Madison, USA; Division of Gene Regulation, Division of Data Science, Research Promotion Headquarters, Fujita Health University, Toyoake, Japan
| | - Melanie L Foster
- Dept. Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Freya M Mowat
- Dept. Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, USA; Dept. Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA; Dept. Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA.
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2
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Barone F, Bunea I, Creel K, Sharma R, Amaral J, Maminishkis A, Bharti K. An Automated Visual Psychophysics Method to Measure Visual Function in Swine Preclinical Animal Model. Transl Vis Sci Technol 2024; 13:8. [PMID: 38470318 PMCID: PMC10941991 DOI: 10.1167/tvst.13.3.8] [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: 09/10/2023] [Accepted: 01/28/2024] [Indexed: 03/13/2024] Open
Abstract
Purpose The aim of this study was to develop and validate a test to assess visual function in pigs using the visual psychophysics contrast sensitivity function. Methods We utilized a touchscreen along with a pellet reward dispenser to train three Göttingen pigs on a visual psychophysics test and determined their contrast sensitivity function. Images with different contrast resolutions were used as visual stimuli and presented against a control image in a two-choice test. Following animals' acclimatization and the first phase of training, the system was arranged such that animals could self-run multiple consecutive trials without human intervention. Results All animals were trained within a week and remembered the task with 1 day of reinforcement when tested 1 month after the last visual assessment. All trained animals performed well during the trial with minimal screen side bias, especially at contrast threshold above 40%. Conclusions Göttingen pigs are trainable for a visual psychophysics test and able to self-run the trial without human intervention. Translational Relevance Contrast sensitivity is one of the key parameters to assess visual function in humans. The possibility of measuring the same parameters in a large animal model allows for a better translation and understanding of drug safety and efficacy in preclinical ophthalmology.
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Affiliation(s)
- Francesca Barone
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD, USA
| | - Irina Bunea
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD, USA
| | - Kristi Creel
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD, USA
| | - Ruchi Sharma
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD, USA
| | - Juan Amaral
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD, USA
| | - Arvydas Maminishkis
- Translational Research Core, Ophthalmic Genetics and Visual Function Branch, National Eye Institute, NIH, Bethesda, MD, USA
| | - Kapil Bharti
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD, USA
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3
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Petersen-Jones SM, Komáromy AM. Canine and Feline Models of Inherited Retinal Diseases. Cold Spring Harb Perspect Med 2024; 14:a041286. [PMID: 37217283 PMCID: PMC10835616 DOI: 10.1101/cshperspect.a041286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Naturally occurring inherited retinal diseases (IRDs) in cats and dogs provide a rich source of potential models for human IRDs. In many cases, the phenotypes between the species with mutations of the homologous genes are very similar. Both cats and dogs have a high-acuity retinal region, the area centralis, an equivalent to the human macula, with tightly packed photoreceptors and higher cone density. This and the similarity in globe size to that of humans means these large animal models provide information not obtainable from rodent models. The established cat and dog models include those for Leber congenital amaurosis, retinitis pigmentosa (including recessive, dominant, and X-linked forms), achromatopsia, Best disease, congenital stationary night blindness and other synaptic dysfunctions, RDH5-associated retinopathy, and Stargardt disease. Several of these models have proven to be important in the development of translational therapies such as gene-augmentation therapies. Advances have been made in editing the canine genome, which necessitated overcoming challenges presented by the specifics of canine reproduction. Feline genome editing presents fewer challenges. We can anticipate the generation of specific cat and dog IRD models by genome editing in the future.
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Affiliation(s)
- Simon M Petersen-Jones
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824, USA
| | - András M Komáromy
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824, USA
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Broeckx BJG. Incorporating Genetic Testing into a Breeding Program. Vet Clin North Am Small Anim Pract 2023:S0195-5616(23)00064-5. [PMID: 37221103 DOI: 10.1016/j.cvsm.2023.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Genetic tests are powerful tools that enable (1) a focus on genetic diversity as mating outcomes can be predicted and thus optimized to minimize or even avoid exclusion and (2) working toward breeding goals by improving a phenotype.
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Affiliation(s)
- Bart J G Broeckx
- Department of Veterinary and Biosciences, Laboratory of Animal Genetics, Faculty of Veterinary Medicine, Ghent University, Heidestraat 19, Merelbeke 9820, Belgium.
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5
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Kim BM, Song HS, Kim JY, Kwon EY, Ha SY, Kim M, Choi JH. Functional characterization of ABCA4 genetic variants related to Stargardt disease. Sci Rep 2022; 12:22282. [PMID: 36566289 PMCID: PMC9790013 DOI: 10.1038/s41598-022-26912-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 12/21/2022] [Indexed: 12/25/2022] Open
Abstract
The ATP-binding cassette subfamily 4 (ABCA4), a transporter, is localized within the photoreceptors of the retina, and its genetic variants cause retinal dystrophy. Despite the clinical importance of the ABCA4 transporter, a few studies have investigated the function of each variant. In this study, we functionally characterized ABCA4 variants found in Korean patients with Stargardt disease or variants of the ABCA4 promoter region. We observed that four missense variants-p.Arg290Gln, p.Thr1117Ala, p.Cys1140Trp, and p.Asn1588Tyr-significantly decreased ABCA4 expression on the plasma membrane, which could be due to intracellular degradation. There are four major haplotypes in the ABCA4 proximal promoter. We observed that the H1 haplotype (c.-761C>A) indicated significantly increased luciferase activity compared to that of the wild-type, whereas the H3 haplotype (c.-1086A>C) indicated significantly decreased luciferase activity (P < 0.01 and 0.001, respectively). In addition, c.-900A>T in the H2 haplotype exhibited significantly increased luciferase activity compared with that of the wild-type. Two transcription factors, GATA-2 and HLF, were found to function as enhancers of ABCA4 transcription. Our findings suggest that ABCA4 variants in patients with Stargardt disease affect ABCA4 expression. Furthermore, common variants of the ABCA4 proximal promoter alter the ABCA4 transcriptional activity, which is regulated by GATA-2 and HLF transcription factors.
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Affiliation(s)
- Bo Min Kim
- grid.255649.90000 0001 2171 7754Department of Pharmacology, Inflammation-Cancer Microenvironment Research Center, College of Medicine, Ewha Womans University, 25 Magokdong-Ro 2-Gil, Gangseo-Gu, Seoul, 07804 Korea
| | - Hyo Sook Song
- grid.255649.90000 0001 2171 7754Department of Pharmacology, Inflammation-Cancer Microenvironment Research Center, College of Medicine, Ewha Womans University, 25 Magokdong-Ro 2-Gil, Gangseo-Gu, Seoul, 07804 Korea
| | - Jin-Young Kim
- grid.255649.90000 0001 2171 7754Department of Pharmacology, Inflammation-Cancer Microenvironment Research Center, College of Medicine, Ewha Womans University, 25 Magokdong-Ro 2-Gil, Gangseo-Gu, Seoul, 07804 Korea
| | - Eun Young Kwon
- grid.255649.90000 0001 2171 7754Department of Pharmacology, Inflammation-Cancer Microenvironment Research Center, College of Medicine, Ewha Womans University, 25 Magokdong-Ro 2-Gil, Gangseo-Gu, Seoul, 07804 Korea
| | - Seung Yeon Ha
- grid.255649.90000 0001 2171 7754Department of Pharmacology, Inflammation-Cancer Microenvironment Research Center, College of Medicine, Ewha Womans University, 25 Magokdong-Ro 2-Gil, Gangseo-Gu, Seoul, 07804 Korea
| | - Minsuk Kim
- grid.255649.90000 0001 2171 7754Department of Pharmacology, Inflammation-Cancer Microenvironment Research Center, College of Medicine, Ewha Womans University, 25 Magokdong-Ro 2-Gil, Gangseo-Gu, Seoul, 07804 Korea
| | - Ji Ha Choi
- grid.255649.90000 0001 2171 7754Department of Pharmacology, Inflammation-Cancer Microenvironment Research Center, College of Medicine, Ewha Womans University, 25 Magokdong-Ro 2-Gil, Gangseo-Gu, Seoul, 07804 Korea
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Ekesten B, Mäkeläinen S, Ellis S, Kjellström U, Bergström TF. Abnormal Appearance of the Area Centralis in Labrador Retrievers With an ABCA4 Loss-of-function Mutation. Transl Vis Sci Technol 2022; 11:36. [PMID: 35201338 PMCID: PMC8883171 DOI: 10.1167/tvst.11.2.36] [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: 11/24/2022] Open
Abstract
PURPOSE To study retinal appearance and morphology in Labrador retrievers (LRs) heterozygous and homozygous for an ABCA4 loss-of-function mutation. METHODS Ophthalmic examination, including ophthalmoscopy and simple testing of vision, was performed in five ABCA4wt/wt, four ABCA4wt/InsC, and six ABCA4InsC/InsC LRs. Retinas were also examined with confocal scanning laser ophthalmoscopy (cSLO) and optical coherence tomography (OCT). Infrared and fundus autofluorescence (FAF) images were studied, and outer nuclear layer (ONL) and neuroretinal thickness were measured in the central and peripheral area centralis. RESULTS Clinical signs in young ABCA4InsC/InsC LRs were subtle, whereas ophthalmoscopic findings and signs of visual impairment were obvious in old ABCA4InsC/InsC LRs. Retinal appearance and vision testing was unremarkable in heterozygous LRs regardless of age. The cSLO/OCT showed abnormal morphology including ONL thinning, abnormal outer retinal layer segmentation, and focal loss of retinal pigment epithelium in the fovea equivalent in juvenile ABCA4InsC/InsC LRs. The abnormal appearance extended into the area centralis and visual streak in middle-aged ABCA4InsC/InsC and then spread more peripherally. A mild phenotype was seen on cSLO/OCT and FAF in middle-aged to old ABCA4wt/InsC LRs. CONCLUSIONS Abnormal appearance and morphology in the fovea equivalent are present in juvenile ABCA4InsC/InsC. In the older affected LRs, the visual streak and then the peripheral retina also develop an abnormal appearance. Vision deteriorates slowly, but some vision is retained throughout life. Older heterozygotes may show a mild retinal phenotype but no obvious visual impairment. The ABCA4InsC/InsC LR is a potential model for ABCA4-mediated retinopathies/juvenile-onset Stargardt disease in a species with human-sized eyes. TRANSLATIONAL RELEVANCE The ABCA4InsC mutation causes juvenile-onset abnormal appearance of the fovea equivalent in affected dogs that slowly spreads in the retina, while only a mild phenotype is seen in older carriers. This is the first non-primate, large-animal model for ABCA4-related/STGD1 retinopathies in a species with a fovea equivalent.
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Affiliation(s)
- Björn Ekesten
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Suvi Mäkeläinen
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.,Department of Medical Biochemistry and Microbiology, Comparative Genetics and Functional Genomics, Uppsala University, Uppsala, Sweden
| | | | | | - Tomas F Bergström
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
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7
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Xiao X, Ye L, Chen C, Zheng H, Yuan J. Clinical Observation and Genotype-Phenotype Analysis of ABCA4- Related Hereditary Retinal Degeneration before Gene Therapy. Curr Gene Ther 2022; 22:342-351. [PMID: 35170407 PMCID: PMC10495610 DOI: 10.2174/1566523222666220216101539] [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: 08/17/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Hereditary retinal degeneration (HRD) is an irreversible eye disease that results in blindness in severe cases. It is most commonly caused by variants in the ABCA4 gene. HRD presents a high degree of clinical and genetic heterogeneity. We determined genotypic and phenotypic correlations, in the natural course of clinical observation, of unrelated progenitors of HRD associated with ABCA4. OBJECTIVE To analyze the relationship between the phenotypes and genotypes of ABCA4 variants. METHODS A retrospective clinical study of five cases from the ophthalmology department of the People's Hospital of Wuhan University from January 2019 to October 2020 was conducted. We tested for ABCA4 variants in the probands. We performed eye tests, including the best-corrected visual acuity, super-wide fundus photography and spontaneous fluorescence photography, optical coherence tomography, and electrophysiological examination. RESULTS Disease-causing variants were identified in the ABCA4 genes of all patients. Among these, seven ABCA4 variants were novel. All patients were sporadic cases; only one patient had parents who were relatives, and the other four patients were offspring of unrelated parents. Two patients presented with Stargardt disease, mainly with macular lesions, two presented with retinitis pigmentosa (cone-rod type), and one presented with cone dystrophy. The visual acuity and visual field of the five patients showed varying degrees of deterioration and impairment. CONCLUSION The same ABCA4 mutation can lead to different clinical phenotypes, and there is variation in the degree of damage to vision, visual field, and electrophysiology among different clinical phenotypes. Clinicians must differentiate between and diagnose pathologies resulting from this mutation.
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Affiliation(s)
- Xuan Xiao
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Hubei, Wuhan 430060, China
| | - Lin Ye
- Department of Eye Plastic and Lacrimal Diseases, Shenzhen Eye Hospital, Shenzhen, China
| | - Changzheng Chen
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Hubei, Wuhan 430060, China
| | - Hongmei Zheng
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Hubei, Wuhan 430060, China
| | - Jiajia Yuan
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Hubei, Wuhan 430060, China
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8
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Molday RS, Garces FA, Scortecci JF, Molday LL. Structure and function of ABCA4 and its role in the visual cycle and Stargardt macular degeneration. Prog Retin Eye Res 2021; 89:101036. [PMID: 34954332 DOI: 10.1016/j.preteyeres.2021.101036] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/07/2021] [Accepted: 12/13/2021] [Indexed: 12/17/2022]
Abstract
ABCA4 is a member of the superfamily of ATP-binding cassette (ABC) transporters that is preferentially localized along the rim region of rod and cone photoreceptor outer segment disc membranes. It uses the energy from ATP binding and hydrolysis to transport N-retinylidene-phosphatidylethanolamine (N-Ret-PE), the Schiff base adduct of retinal and phosphatidylethanolamine, from the lumen to the cytoplasmic leaflet of disc membranes. This ensures that all-trans-retinal and excess 11-cis-retinal are efficiently cleared from photoreceptor cells thereby preventing the accumulation of toxic retinoid compounds. Loss-of-function mutations in the gene encoding ABCA4 cause autosomal recessive Stargardt macular degeneration, also known as Stargardt disease (STGD1), and related autosomal recessive retinopathies characterized by impaired central vision and an accumulation of lipofuscin and bis-retinoid compounds. High resolution structures of ABCA4 in its substrate and nucleotide free state and containing bound N-Ret-PE or ATP have been determined by cryo-electron microscopy providing insight into the molecular architecture of ABCA4 and mechanisms underlying substrate recognition and conformational changes induced by ATP binding. The expression and functional characterization of a large number of disease-causing missense ABCA4 variants have been determined. These studies have shed light into the molecular mechanisms underlying Stargardt disease and a classification that reliably predicts the effect of a specific missense mutation on the severity of the disease. They also provide a framework for developing rational therapeutic treatments for ABCA4-associated diseases.
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Affiliation(s)
- Robert S Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada; Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, B.C., Canada.
| | - Fabian A Garces
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
| | | | - Laurie L Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
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9
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Tao L, He D, Liao C, Cai B, Chen C, Wang Y, Chen J, Liu Z, Wu Y. Repressing c-Jun N-terminal kinase signaling mitigates retinal pigment epithelium degeneration in mice with failure to clear all-trans-retinal. Exp Eye Res 2021; 214:108877. [PMID: 34863682 DOI: 10.1016/j.exer.2021.108877] [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: 06/18/2021] [Revised: 11/04/2021] [Accepted: 11/29/2021] [Indexed: 11/04/2022]
Abstract
Retinal pigment epithelium (RPE) cell apoptosis arising from all-trans-retinal (atRAL) is in close contact with the etiology of dry age-related macular degeneration (AMD) and autosomal recessive Stargardt's disease (STGD1), but its underlying mechanisms remain elusive. In this study, we reported that c-Jun N-terminal kinase (JNK) activation facilitated atRAL-induced apoptosis of RPE cells. Reactive oxygen species production and endoplasmic reticulum stress were identified as two of major upstream events responsible for activating JNK signaling in atRAL-loaded RPE cells. Inhibiting JNK signaling rescued RPE cells from apoptosis induced by atRAL through attenuating caspase-3 activation leading to poly-ADP-ribose polymerase (PARP) cleavage, and DNA damage response. Abca4-/-Rdh8-/- mice upon light exposure exhibit rapidly increased accumulation of atRAL in the retina, and display severe RPE degeneration, a primary attribute of dry AMD and STGD1. Reducing JNK signaling by intraperitoneally injected JNK-IN-8 was highly effective in preventing RPE atrophy and apoptosis in light-exposed Abca4-/-Rdh8-/- mice. These findings afford a further understanding for contribution of JNK activation by atRAL to retinal damage.
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Affiliation(s)
- Lei Tao
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Fujian Engineering and Research Center of Eye Regenerative Medicine, Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Danxue He
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Fujian Engineering and Research Center of Eye Regenerative Medicine, Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Chunyan Liao
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Fujian Engineering and Research Center of Eye Regenerative Medicine, Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Binxiang Cai
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Fujian Engineering and Research Center of Eye Regenerative Medicine, Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Chao Chen
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Fujian Engineering and Research Center of Eye Regenerative Medicine, Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Yan Wang
- Department of Ophthalmology, South China Hospital, Health Science Center, Shenzhen University, Shenzhen, Guangdong, China
| | - Jingmeng Chen
- School of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Zuguo Liu
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Fujian Engineering and Research Center of Eye Regenerative Medicine, Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Yalin Wu
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Fujian Engineering and Research Center of Eye Regenerative Medicine, Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, China; Xiamen Eye Center of Xiamen University, Xiamen, Fujian, China; Shenzhen Research Institute of Xiamen University, Shenzhen, Guangdong, China.
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10
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Cronin T, Croyal M, Provost N, Ducloyer JB, Mendes-Madeira A, Libeau L, Morival C, Toublanc E, Audrain C, Isiegas C, Pichard V, Adjali O. Effect of retinol dehydrogenase gene transfer in a novel rat model of Stargardt disease. FASEB J 2021; 35:e21934. [PMID: 34599778 DOI: 10.1096/fj.202002525rrr] [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: 11/30/2020] [Revised: 08/25/2021] [Accepted: 09/03/2021] [Indexed: 11/11/2022]
Abstract
Dysfunction of the ATPase-binding Cassette Transporter protein (ABCA4) can lead to early onset macular degeneration, in particular to Stargardt disease. To enable translational research into this form of blindness, we evaluated the effect of Cas9-induced disruptions of the ABCA4 gene to potentially generate new transgenic rat models of the disease. We show that deletion of the short exon preceding the second nucleotide-binding domain is sufficient to drastically knock down protein levels and results in accumulation of retinoid dimers similar to that associated with Stargardt disease. Overexpression of the retinol dehydrogenase enzymes RDH8 and RDH12 can to a limited extent offset the increase in the bisretinoid levels in the Abca4Ex42-/ - KO rats possibly by restricting the time window in which retinal can dimerize before being reduced to retinol. However, in vivo imaging shows that overexpression of RDH8 can induce retinal degeneration. This may be due to the depletion in the outer segment of the cofactor NADPH, needed for RDH function. The translational potential of RDH therapy as well as other Stargardt disease therapies can be tested using the Abca4 knockdown rat model.
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Affiliation(s)
- T Cronin
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | | | - N Provost
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - J B Ducloyer
- Department of Ophthalmology, University Hospital of Nantes, CHU de Nantes, Nantes, France
| | - A Mendes-Madeira
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - L Libeau
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - C Morival
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - E Toublanc
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - C Audrain
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - C Isiegas
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - V Pichard
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - O Adjali
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
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11
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Huang D, Heath Jeffery RC, Aung-Htut MT, McLenachan S, Fletcher S, Wilton SD, Chen FK. Stargardt disease and progress in therapeutic strategies. Ophthalmic Genet 2021; 43:1-26. [PMID: 34455905 DOI: 10.1080/13816810.2021.1966053] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background: Stargardt disease (STGD1) is an autosomal recessive retinal dystrophy due to mutations in ABCA4, characterized by subretinal deposition of lipofuscin-like substances and bilateral centrifugal vision loss. Despite the tremendous progress made in the understanding of STGD1, there are no approved treatments to date. This review examines the challenges in the development of an effective STGD1 therapy.Materials and Methods: A literature review was performed through to June 2021 summarizing the spectrum of retinal phenotypes in STGD1, the molecular biology of ABCA4 protein, the in vivo and in vitro models used to investigate the mechanisms of ABCA4 mutations and current clinical trials.Results: STGD1 phenotypic variability remains an challenge for clinical trial design and patient selection. Pre-clinical development of therapeutic options has been limited by the lack of animal models reflecting the diverse phenotypic spectrum of STDG1. Patient-derived cell lines have facilitated the characterization of splice mutations but the clinical presentation is not always predicted by the effect of specific mutations on retinoid metabolism in cellular models. Current therapies primarily aim to delay vision loss whilst strategies to restore vision are less well developed.Conclusions: STGD1 therapy development can be accelerated by a deeper understanding of genotype-phenotype correlations.
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Affiliation(s)
- Di Huang
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Western Australia, Australia.,Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), the University of Western Australia, Nedlands, Western Australia, Australia.,Perron Institute for Neurological and Translational Science & the University of Western Australia, Nedlands, Western Australia, Australia
| | - Rachael C Heath Jeffery
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), the University of Western Australia, Nedlands, Western Australia, Australia
| | - May Thandar Aung-Htut
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Western Australia, Australia.,Perron Institute for Neurological and Translational Science & the University of Western Australia, Nedlands, Western Australia, Australia
| | - Samuel McLenachan
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), the University of Western Australia, Nedlands, Western Australia, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Western Australia, Australia.,Perron Institute for Neurological and Translational Science & the University of Western Australia, Nedlands, Western Australia, Australia
| | - Steve D Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Western Australia, Australia.,Perron Institute for Neurological and Translational Science & the University of Western Australia, Nedlands, Western Australia, Australia
| | - Fred K Chen
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), the University of Western Australia, Nedlands, Western Australia, Australia.,Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia.,Department of Ophthalmology, Royal Perth Hospital, Perth, Western Australia, Australia.,Department of Ophthalmology, Perth Children's Hospital, Nedlands, Western Australia, Australia
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12
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Abstract
Inherited retinal diseases (IRDs) are an important cause of blindness worldwide. Over 270 genes have been associated with IRD. Genetic testing can determine the cause of the clinical disease in the majority of patients. However, at least 25-50% of patients with clinical diagnosis of IRD remain unsolved even after whole genome sequencing. Animal models of IRD can be useful for expanding the set of established IRD genes, to gain biological understanding of the function of these genes in the retina, and to test advanced therapeutics prior to human clinical trials. In this chapter some small and large animal models of IRD are discussed including some of the advantages and limitations of each for various forms of retinopathy.
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13
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Zhu Q, Rui X, Li Y, You Y, Sheng XL, Lei B. Identification of Four Novel Variants and Determination of Genotype-Phenotype Correlations for ABCA4 Variants Associated With Inherited Retinal Degenerations. Front Cell Dev Biol 2021; 9:634843. [PMID: 33732702 PMCID: PMC7957020 DOI: 10.3389/fcell.2021.634843] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 01/26/2021] [Indexed: 12/21/2022] Open
Abstract
Purpose The purpose of the study is to describe the genetic and clinical features of 17 patients with ABCA4-related inherited retinal degenerations (IRDs) and define the phenotype–genotype correlations. Methods In this multicenter retrospective study, 17 patients from 16 families were enrolled, and ABCA4 gene variants were detected using targeted next-generation sequencing using a custom designed panel for IRDs. Sanger sequencing and co-segregation analysis of the suspected pathogenic variants were performed with the family members. The pathogenicities of variants were evaluated according to the American College of Medical Genetics and Genomics guidelines (ACMG). Protein structure modifications mediated by the variants were studied using bioinformatic analyses. Results The probands were diagnosed with Stargardt disease 1 (7), cone-rod dystrophy type 3 (8), cone dystrophy (1), and retinitis pigmentosa 19 (1). Onset of symptoms occurred between 5 and 27 years of age (median age = 12.4 years). A total of 30 unique ABCA4 suspicious pathogenic variations were observed, including 18 missense mutations, seven frameshift mutations, two nonsense mutations, one canonical splice site mutation, one small in-frame deletion, and one insertion. Four novel ABCA4 variants were identified. Two novel frameshift variants, c.1290dupC (p.W431fs), and c.2967dupT (G990fs), were determined to be pathogenic. A novel missense variant c.G5761T (p.V1921L) was likely pathogenic, and another novel missense c.C170G (p.P57R) variant was of undetermined significance. All ABCA4 variants tested in this study inordinately changed the physico-chemical parameters and structure of protein based on in silico analysis. Conclusion ABCA4-related IRD is genetically and clinically highly heterogeneous. Four novel ABCA4 variants were identified. This study will expand the spectrum of disease-causing variants in ABCA4, which will further facilitate genetic counseling.
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Affiliation(s)
- Qing Zhu
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China
| | - Xue Rui
- Ningxia Clinical Research Center of Blinding Eye Disease, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, First Affiliated Hospital of Northwest University for Nationalities, Yinchuan, China
| | - Ya Li
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China.,Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute and Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
| | - Ya You
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China.,Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute and Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
| | - Xun-Lun Sheng
- Ningxia Clinical Research Center of Blinding Eye Disease, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, First Affiliated Hospital of Northwest University for Nationalities, Yinchuan, China
| | - Bo Lei
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China.,Henan Branch of National Clinical Research Center for Ocular Diseases, Henan Eye Institute and Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou, China
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14
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Garces FA, Scortecci JF, Molday RS. Functional Characterization of ABCA4 Missense Variants Linked to Stargardt Macular Degeneration. Int J Mol Sci 2020; 22:ijms22010185. [PMID: 33375396 PMCID: PMC7796138 DOI: 10.3390/ijms22010185] [Citation(s) in RCA: 12] [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: 11/27/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 12/17/2022] Open
Abstract
ABCA4 is an ATP-binding cassette (ABC) transporter expressed in photoreceptors, where it transports its substrate, N-retinylidene-phosphatidylethanolamine (N-Ret-PE), across outer segment membranes to facilitate the clearance of retinal from photoreceptors. Mutations in ABCA4 cause Stargardt macular degeneration (STGD1), an autosomal recessive disorder characterized by a loss of central vision and the accumulation of bisretinoid compounds. The purpose of this study was to determine the molecular properties of ABCA4 variants harboring disease-causing missense mutations in the transmembrane domains. Thirty-eight variants expressed in culture cells were analyzed for expression, ATPase activities, and substrate binding. On the basis of these properties, the variants were divided into three classes: Class 1 (severe variants) exhibited significantly reduced ABCA4 expression and basal ATPase activity that was not stimulated by its substrate N-Ret-PE; Class 2 (moderate variants) showed a partial reduction in expression and basal ATPase activity that was modestly stimulated by N-Ret-PE; and Class 3 (mild variants) displayed expression and functional properties comparable to normal ABCA4. The p.R653C variant displayed normal expression and basal ATPase activity, but lacked substrate binding and ATPase activation, suggesting that arginine 653 contributes to N-Ret-PE binding. Our classification provides a basis for better understanding genotype–phenotype correlations and evaluating therapeutic treatments for STGD1.
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Affiliation(s)
- Fabian A. Garces
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (F.A.G.); (J.F.S.)
| | - Jessica F. Scortecci
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (F.A.G.); (J.F.S.)
| | - Robert S. Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (F.A.G.); (J.F.S.)
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC V5Z 3N9, Canada
- Correspondence: ; Tel.: +1-604-822-6173
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15
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Curtis SB, Molday LL, Garces FA, Molday RS. Functional analysis and classification of homozygous and hypomorphic ABCA4 variants associated with Stargardt macular degeneration. Hum Mutat 2020; 41:1944-1956. [PMID: 32845050 DOI: 10.1002/humu.24100] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/06/2020] [Accepted: 08/24/2020] [Indexed: 12/14/2022]
Abstract
Stargardt macular degeneration (Stargardt disease 1 [STGD1]) is caused by mutations in the gene encoding ABCA4, an ATP-binding cassette protein that transports N-retinylidene-phosphatidylethanolamine (N-Ret-PE) across photoreceptor membranes. Reduced ABCA4 activity results in retinoid accumulation leading to photoreceptor degeneration. The disease onset and severity vary from severe loss in visual acuity in the first decade to mild visual impairment late in life. We determined the effect of 22 disease-causing missense mutations on the expression and ATPase activity of ABCA4 in the absence and presence of N-Ret-PE. Three classes were identified that correlated with the disease onset in homozygous STGD1 individuals: Class 1 exhibited reduced ABCA4 expression and ATPase activity that was not stimulated by N-Ret-PE; individuals homozygous for these variants had an early disease onset (≤13 years); Class 2 showed reduced ATPase activity with limited stimulation by N-Ret-PE; these correlated with moderate disease onset (14-40 years); and Class 3 displayed high expression and ATPase activity that was strongly activated by N-Ret-PE; these were associated with late disease onset (>40 years). On the basis of our results, we introduce a functionality index for gauging the effect of missense mutations on STGD1 severity. Our studies support the mild phenotype exhibited by the p.Gly863Ala, p.Asn1868Ile, and p.Gly863Ala/p.Asn1868Ile variants.
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Affiliation(s)
- Susan B Curtis
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Laurie L Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Fabian A Garces
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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16
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Molecular Analysis of the ABCA4 Gene Mutations in Patients with Stargardt Disease Using Human Hair Follicles. Int J Mol Sci 2020; 21:ijms21103430. [PMID: 32413971 PMCID: PMC7279462 DOI: 10.3390/ijms21103430] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/05/2020] [Accepted: 05/10/2020] [Indexed: 12/17/2022] Open
Abstract
ABCA4 gene mutations are the cause of a spectrum of ABCA4 retinopathies, and the most common juvenile macular degeneration is called Stargardt disease. ABCA4 has previously been observed almost exclusively in the retina. Therefore, studying the functional consequences of ABCA4 variants has required advanced molecular analysis techniques. The aim of the present study was to evaluate whether human hair follicles may be used for molecular analysis of the ABCA4 gene splice-site variants in patients with ABCA4 retinopathies. We assessed ABCA4 expression in hair follicles and skin at mRNA and protein levels by means of real-time PCR and Western blot analyses, respectively. We performed cDNA sequencing to reveal the presence of full-length ABCA4 transcripts and analyzed ABCA4 transcripts from three patients with Stargardt disease carrying different splice-site ABCA4 variants: c.5312+1G>A, c.5312+2T>G and c.5836-3C>A. cDNA analysis revealed that c.5312+1G>A, c.5312+2T>G variants led to the skipping of exon 37, and the c.5836-3C>A variant resulted in the insertion of 30 nucleotides into the transcript. Our results strongly argue for the use of hair follicles as a model for the molecular analysis of the pathogenicity of ABCA4 variants in patients with ABCA4 retinopathies.
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17
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Cremers FPM, Lee W, Collin RWJ, Allikmets R. Clinical spectrum, genetic complexity and therapeutic approaches for retinal disease caused by ABCA4 mutations. Prog Retin Eye Res 2020; 79:100861. [PMID: 32278709 PMCID: PMC7544654 DOI: 10.1016/j.preteyeres.2020.100861] [Citation(s) in RCA: 164] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 12/18/2022]
Abstract
The ABCA4 protein (then called a “rim protein”) was first
identified in 1978 in the rims and incisures of rod photoreceptors. The
corresponding gene, ABCA4, was cloned in 1997, and variants
were identified as the cause of autosomal recessive Stargardt disease (STGD1).
Over the next two decades, variation in ABCA4 has been
attributed to phenotypes other than the classically defined STGD1 or fundus
flavimaculatus, ranging from early onset and fast progressing cone-rod dystrophy
and retinitis pigmentosa-like phenotypes to very late onset cases of mostly mild
disease sometimes resembling, and confused with, age-related macular
degeneration. Similarly, analysis of the ABCA4 locus uncovered
a trove of genetic information, including >1200 disease-causing mutations
of varying severity, and of all types – missense, nonsense, small
deletions/insertions, and splicing affecting variants, of which many are located
deep-intronic. Altogether, this has greatly expanded our understanding of
complexity not only of the diseases caused by ABCA4 mutations,
but of all Mendelian diseases in general. This review provides an in depth
assessment of the cumulative knowledge of ABCA4-associated retinopathy –
clinical manifestations, genetic complexity, pathophysiology as well as current
and proposed therapeutic approaches.
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Affiliation(s)
- Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands.
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Genetics & Development, Columbia University, New York, NY, 10032, USA
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Pathology & Cell Biology, Columbia University, New York, NY, 10032, USA.
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18
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Winkler PA, Occelli LM, Petersen-Jones SM. Large Animal Models of Inherited Retinal Degenerations: A Review. Cells 2020; 9:cells9040882. [PMID: 32260251 PMCID: PMC7226744 DOI: 10.3390/cells9040882] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 12/13/2022] Open
Abstract
Studies utilizing large animal models of inherited retinal degeneration (IRD) have proven important in not only the development of translational therapeutic approaches, but also in improving our understanding of disease mechanisms. The dog is the predominant species utilized because spontaneous IRD is common in the canine pet population. Cats are also a source of spontaneous IRDs. Other large animal models with spontaneous IRDs include sheep, horses and non-human primates (NHP). The pig has also proven valuable due to the ease in which transgenic animals can be generated and work is ongoing to produce engineered models of other large animal species including NHP. These large animal models offer important advantages over the widely used laboratory rodent models. The globe size and dimensions more closely parallel those of humans and, most importantly, they have a retinal region of high cone density and denser photoreceptor packing for high acuity vision. Laboratory rodents lack such a retinal region and, as macular disease is a critical cause for vision loss in humans, having a comparable retinal region in model species is particularly important. This review will discuss several large animal models which have been used to study disease mechanisms relevant for the equivalent human IRD.
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19
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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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20
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Patel MJ, Biswas SB, Biswas-Fiss EE. Functional significance of the conserved C-Terminal VFVNFA motif in the retina-specific ABC transporter, ABCA4, and its role in inherited visual disease. Biochem Biophys Res Commun 2019; 519:46-52. [PMID: 31481235 DOI: 10.1016/j.bbrc.2019.08.121] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 08/23/2019] [Indexed: 01/24/2023]
Abstract
The human retina-specific ATP binding cassette transporter, ABCA4, plays a significant role in the visual cycle. Mutations in the ABCA4 gene result in a broad spectrum of severe, blinding, retinal degenerative diseases, including Stargardt macular dystrophy, fundus flavimaculatus, autosomal recessive (ar)-retinitis pigmentosa, and ar-cone-rod dystrophy. Genetic testing frequently yields novel variants of unknown significance, making accurate prognosis and therapeutic approaches difficult. Recently, we have reported a novel variant of ABCA4 corresponding to a four-nucleotide deletion which led to a premature stop codon and loss of the last 161 amino acids, including the highly-conserved VFVNFA motif. Despite the presence of this motif among other ABCA proteins, knowledge of the functional significance of this sequence remains limited. In this study, we have conducted structural and functional analyses of recombinant ABCA4 polypeptides with altered VFVNFA motifs to evaluate the importance of this sequence. Further investigation of ABCA4 subdomain interactions, using Fluorescence Resonance Energy Transfer, demonstrated a loss of interaction between nucleotide binding domains in the absence of the VFVNFA motif.
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Affiliation(s)
- Meera J Patel
- Department of Medical and Molecular Sciences, University of Delaware, College of Health Sciences, Newark, DE 19716, USA.
| | - Subhasis B Biswas
- Department of Medical and Molecular Sciences, University of Delaware, College of Health Sciences, Newark, DE 19716, USA. %26
| | - Esther E Biswas-Fiss
- Department of Medical and Molecular Sciences, University of Delaware, College of Health Sciences, Newark, DE 19716, USA.
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21
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A SIX6 Nonsense Variant in Golden Retrievers with Congenital Eye Malformations. Genes (Basel) 2019; 10:genes10060454. [PMID: 31207931 PMCID: PMC6628151 DOI: 10.3390/genes10060454] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/04/2019] [Accepted: 06/11/2019] [Indexed: 12/22/2022] Open
Abstract
Causative genetic variants for more than 30 heritable eye disorders in dogs have been reported. For other clinically described eye disorders, the genetic cause is still unclear. We investigated four Golden Retriever litters segregating for highly variable congenital eye malformations. Several affected puppies had unilateral or bilateral retina dysplasia and/or optic nerve hypoplasia. The four litters shared the same father or grandfather suggesting a heritable condition with an autosomal dominant mode of inheritance. The genome of one affected dog was sequenced and compared to 601 control genomes. A heterozygous private nonsense variant, c.487C>T, was found in the SIX6 gene. This variant is predicted to truncate about a third of the open reading frame, p.(Gln163*). We genotyped all available family members and 464 unrelated Golden Retrievers. All three available cases were heterozygous. Five additional close relatives including the common sire were also heterozygous, but did not show any obvious eye phenotypes. The variant was absent from the 464 unrelated Golden Retrievers and 17 non-affected siblings of the cases. The SIX6 protein is a homeobox transcription factor with a known role in eye development. In humans and other species, SIX6 loss of function variants were reported to cause congenital eye malformations. This strongly suggests that the c.487C>T variant detected contributed to the observed eye malformations. We hypothesize that the residual amount of functional SIX6 protein likely to be expressed in heterozygous dogs is sufficient to explain the observed incomplete penetrance and the varying severity of the eye defects in the affected dogs.
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