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Bhoi JD, Goel M, Ribelayga CP, Mangel SC. Circadian clock organization in the retina: From clock components to rod and cone pathways and visual function. Prog Retin Eye Res 2023; 94:101119. [PMID: 36503722 PMCID: PMC10164718 DOI: 10.1016/j.preteyeres.2022.101119] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 08/22/2022] [Accepted: 08/25/2022] [Indexed: 12/13/2022]
Abstract
Circadian (24-h) clocks are cell-autonomous biological oscillators that orchestrate many aspects of our physiology on a daily basis. Numerous circadian rhythms in mammalian and non-mammalian retinas have been observed and the presence of an endogenous circadian clock has been demonstrated. However, how the clock and associated rhythms assemble into pathways that support and control retina function remains largely unknown. Our goal here is to review the current status of our knowledge and evaluate recent advances. We describe many previously-observed retinal rhythms, including circadian rhythms of morphology, biochemistry, physiology, and gene expression. We evaluate evidence concerning the location and molecular machinery of the retinal circadian clock, as well as consider findings that suggest the presence of multiple clocks. Our primary focus though is to describe in depth circadian rhythms in the light responses of retinal neurons with an emphasis on clock control of rod and cone pathways. We examine evidence that specific biochemical mechanisms produce these daily light response changes. We also discuss evidence for the presence of multiple circadian retinal pathways involving rhythms in neurotransmitter activity, transmitter receptors, metabolism, and pH. We focus on distinct actions of two dopamine receptor systems in the outer retina, a dopamine D4 receptor system that mediates circadian control of rod/cone gap junction coupling and a dopamine D1 receptor system that mediates non-circadian, light/dark adaptive regulation of gap junction coupling between horizontal cells. Finally, we evaluate the role of circadian rhythmicity in retinal degeneration and suggest future directions for the field of retinal circadian biology.
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Affiliation(s)
- Jacob D Bhoi
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA; Neuroscience Honors Research Program, William Marsh Rice University, Houston, TX, USA
| | - Manvi Goel
- Department of Neuroscience, Wexner Medical Center, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Christophe P Ribelayga
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA; Neuroscience Honors Research Program, William Marsh Rice University, Houston, TX, USA.
| | - Stuart C Mangel
- Department of Neuroscience, Wexner Medical Center, College of Medicine, The Ohio State University, Columbus, OH, USA.
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2
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Chew LA, Iannaccone A. Gene-agnostic approaches to treating inherited retinal degenerations. Front Cell Dev Biol 2023; 11:1177838. [PMID: 37123404 PMCID: PMC10133473 DOI: 10.3389/fcell.2023.1177838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/31/2023] [Indexed: 05/02/2023] Open
Abstract
Most patients with inherited retinal degenerations (IRDs) have been waiting for treatments that are "just around the corner" for decades, with only a handful of seminal breakthroughs happening in recent years. Highlighting the difficulties in the quest for curative therapeutics, Luxturna required 16 years of development before finally obtaining United States Food and Drug Administration (FDA) approval and its international equivalents. IRDs are both genetically and phenotypically heterogeneous. While this diversity offers many opportunities for gene-by-gene precision medicine-based approaches, it also poses a significant challenge. For this reason, alternative (or parallel) strategies to identify more comprehensive, across-the-board therapeutics for the genetically and phenotypically diverse IRD patient population are very appealing. Even when gene-specific approaches may be available and become approved for use, many patients may have reached a disease stage whereby these approaches may no longer be viable. Thus, alternate visual preservation or restoration therapeutic approaches are needed at these stages. In this review, we underscore several gene-agnostic approaches that are being developed as therapeutics for IRDs. From retinal supplementation to stem cell transplantation, optogenetic therapy and retinal prosthetics, these strategies would bypass at least in part the need for treating every individual gene or mutation or provide an invaluable complement to them. By considering the diverse patient population and treatment strategies suited for different stages and patterns of retinal degeneration, gene agnostic approaches are very well poised to impact favorably outcomes and prognosis for IRD patients.
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Affiliation(s)
- Lindsey A. Chew
- Duke Center for Retinal Degenerations and Ophthalmic Genetic Diseases, Department of Ophthalmology, Duke Eye Center, Duke University School of Medicine, Durham, NC, United States
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, United States
| | - Alessandro Iannaccone
- Duke Center for Retinal Degenerations and Ophthalmic Genetic Diseases, Department of Ophthalmology, Duke Eye Center, Duke University School of Medicine, Durham, NC, United States
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3
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Jaroszynska N, Harding P, Moosajee M. Metabolism in the Zebrafish Retina. J Dev Biol 2021; 9:10. [PMID: 33804189 PMCID: PMC8006245 DOI: 10.3390/jdb9010010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 03/08/2021] [Accepted: 03/11/2021] [Indexed: 12/12/2022] Open
Abstract
Retinal photoreceptors are amongst the most metabolically active cells in the body, consuming more glucose as a metabolic substrate than even the brain. This ensures that there is sufficient energy to establish and maintain photoreceptor functions during and after their differentiation. Such high dependence on glucose metabolism is conserved across vertebrates, including zebrafish from early larval through to adult retinal stages. As the zebrafish retina develops rapidly, reaching an adult-like structure by 72 hours post fertilisation, zebrafish larvae can be used to study metabolism not only during retinogenesis, but also in functionally mature retinae. The interplay between rod and cone photoreceptors and the neighbouring retinal pigment epithelium (RPE) cells establishes a metabolic ecosystem that provides essential control of their individual functions, overall maintaining healthy vision. The RPE facilitates efficient supply of glucose from the choroidal vasculature to the photoreceptors, which produce metabolic products that in turn fuel RPE metabolism. Many inherited retinal diseases (IRDs) result in photoreceptor degeneration, either directly arising from photoreceptor-specific mutations or secondary to RPE loss, leading to sight loss. Evidence from a number of vertebrate studies suggests that the imbalance of the metabolic ecosystem in the outer retina contributes to metabolic failure and disease pathogenesis. The use of larval zebrafish mutants with disease-specific mutations that mirror those seen in human patients allows us to uncover mechanisms of such dysregulation and disease pathology with progression from embryonic to adult stages, as well as providing a means of testing novel therapeutic approaches.
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Affiliation(s)
| | - Philippa Harding
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK;
| | - Mariya Moosajee
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK;
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
- The Francis Crick Institute, London NW1 1AT, UK
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4
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Narayan DS, Wood JPM, Chidlow G, Casson RJ. A review of the mechanisms of cone degeneration in retinitis pigmentosa. Acta Ophthalmol 2016; 94:748-754. [PMID: 27350263 DOI: 10.1111/aos.13141] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/30/2016] [Indexed: 12/12/2022]
Abstract
Retinitis pigmentosa (RP) is an inherited condition that features degeneration of rod and cone photoreceptors. In all forms of RP, the genetic mutation is expressed exclusively in rods; however, cones die too. The secondary death of cones in RP remains somewhat mysterious. A better understanding of the mechanisms that cause cone degeneration in RP could lead to novel treatments that preserve cones. There are a number of prevailing theories that attempt to explain cone degeneration in RP. One concept is that cone survival is dependent on trophic factors produced by rods. Another hypothesis is that cones suffer from a nutrient shortage after rods have been lost. Additionally, oxidative stress and pro-inflammatory microglial activation have also been suggested to play a role in cone death. The present review evaluates the evidence supporting these theories and provides an update on the mechanisms of cone degeneration in RP.
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Affiliation(s)
- Daniel S. Narayan
- Ophthalmic Research Laboratories; Hanson Institute Centre for Neurological Diseases; Adelaide South Australia Australia
- South Australian Institute of Ophthalmology; University of Adelaide; Adelaide South Australia Australia
| | - John P. M. Wood
- Ophthalmic Research Laboratories; Hanson Institute Centre for Neurological Diseases; Adelaide South Australia Australia
- South Australian Institute of Ophthalmology; University of Adelaide; Adelaide South Australia Australia
| | - Glyn Chidlow
- Ophthalmic Research Laboratories; Hanson Institute Centre for Neurological Diseases; Adelaide South Australia Australia
- South Australian Institute of Ophthalmology; University of Adelaide; Adelaide South Australia Australia
| | - Robert J. Casson
- Ophthalmic Research Laboratories; Hanson Institute Centre for Neurological Diseases; Adelaide South Australia Australia
- South Australian Institute of Ophthalmology; University of Adelaide; Adelaide South Australia Australia
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5
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Zhang L, Justus S, Xu Y, Pluchenik T, Hsu CW, Yang J, Duong JK, Lin CS, Jia Y, Bassuk AG, Mahajan VB, Tsang SH. Reprogramming towards anabolism impedes degeneration in a preclinical model of retinitis pigmentosa. Hum Mol Genet 2016; 25:4244-4255. [PMID: 27516389 DOI: 10.1093/hmg/ddw256] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 06/25/2016] [Accepted: 07/22/2016] [Indexed: 11/14/2022] Open
Abstract
Retinitis pigmentosa (RP) is an incurable neurodegenerative condition featuring photoreceptor death that leads to blindness. Currently, there is no approved therapeutic for photoreceptor degenerative conditions like RP and atrophic age-related macular degeneration (AMD). Although there are promising results in human gene therapy, RP is a genetically diverse disorder, such that gene-specific therapies would be practical in a small fraction of patients with RP. Here, we explore a non-gene-specific strategy that entails reprogramming photoreceptors towards anabolism by upregulating the mechanistic target of rapamycin (mTOR) pathway. We conditionally ablated the tuberous sclerosis complex 1 (Tsc1) gene, an mTOR inhibitor, in the rods of the Pde6bH620Q/H620Q preclinical RP mouse model and observed, functionally and morphologically, an improvement in the survival of rods and cones at early and late disease stages. These results elucidate the ability of reprogramming the metabolome to slow photoreceptor degeneration. This strategy may also be applicable to a wider range of neurodegenerative diseases, as enhancement of nutrient uptake is not gene-specific and is implicated in multiple pathologies. Enhancing anabolism promoted neuronal survival and function and could potentially benefit a number of photoreceptor and other degenerative conditions.
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Affiliation(s)
- Lijuan Zhang
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA.,Shanxi Eye Hospital, affiliated with Shanxi Medical University, Xinghualing, Taiyuan, Shanxi, China
| | - Sally Justus
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
| | - Yu Xu
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA.,Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Tamara Pluchenik
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
| | - Chun-Wei Hsu
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
| | - Jin Yang
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA.,Tianjin Medical University Eye Hospital, Tianjin, China
| | - Jimmy K Duong
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York, USA
| | - Chyuan-Sheng Lin
- Department of Pathology and Cell Biology, Transgenic Animal Facility, Herbert Irving Comprehensive Cancer Center, College of Physicians and Surgeons of Columbia University, New York, NY, USA
| | - Yading Jia
- Shanxi Eye Hospital, affiliated with Shanxi Medical University, Xinghualing, Taiyuan, Shanxi, China
| | - Alexander G Bassuk
- Department of Pediatrics and Neurology, University of Iowa, Iowa City, IA
| | - Vinit B Mahajan
- Omics Laboratory, University of Iowa, Iowa City, IA, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Stephen H Tsang
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA .,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
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6
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Roska B, Busskamp V, Sahel JA, Picaud S. [Retinitis pigmentosa: eye sight restoration by optogenetic therapy]. Biol Aujourdhui 2013; 207:109-121. [PMID: 24103341 DOI: 10.1051/jbio/2013011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Indexed: 06/02/2023]
Abstract
Retinitis pigmentosa (RP) is a hereditary retinal disease leading to blindness, which affects two million people worldwide. Restoring vision in these blind patients was proposed by gene delivery of microbial light-activated ionic channels or pumps "optogenetic proteins" to transform surviving cells into artificial photoreceptors. This therapeutic strategy was validated in blind animal models of RP by recording at the level of the retina and cortex and by behavioural tests. The translational potentials of these optogenetic approaches have been evaluated using in vitro studies on post-mortem human retinal tissues. Here, we review these recent results and discuss the potential clinical applications of the optogenetic therapy for RP patients.
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Affiliation(s)
- Botond Roska
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66F, 4058 Basel, Switzerland
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7
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Cramer AO, MacLaren RE. Translating induced pluripotent stem cells from bench to bedside: application to retinal diseases. Curr Gene Ther 2013; 13:139-51. [PMID: 23320477 PMCID: PMC3826973 DOI: 10.2174/1566523211313020008] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/09/2013] [Accepted: 01/11/2013] [Indexed: 12/17/2022]
Abstract
Induced pluripotent stem cells (iPSc) are a scientific and medical frontier. Application of reprogrammed somatic cells for clinical trials is in its dawn period; advances in research with animal and human iPSc are paving the way for retinal therapies with the ongoing development of safe animal cell transplantation studies and characterization of patient- specific and disease-specific human iPSc. The retina is an optimal model for investigation of neural regeneration; amongst other advantageous attributes, it is the most accessible part of the CNS for surgery and outcome monitoring. A recent clinical trial showing a degree of visual restoration via a subretinal electronic prosthesis implies that even a severely degenerate retina may have the capacity for repair after cell replacement through potential plasticity of the visual system. Successful differentiation of neural retina from iPSc and the recent generation of an optic cup from human ESc invitro increase the feasibility of generating an expandable and clinically suitable source of cells for human clinical trials. In this review we shall present recent studies that have propelled the field forward and discuss challenges in utilizing iPS cell derived retinal cells as reliable models for clinical therapies and as a source for clinical cell transplantation treatment for patients suffering from genetic retinal disease.
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Affiliation(s)
- Alona O. Cramer
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, NIHR Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Merton College, University of Oxford, Oxford OX1 4JD, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, NIHR Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Merton College, University of Oxford, Oxford OX1 4JD, UK
- Moorfields Eye Hospital, London EC1V 2PD, UK
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8
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Nita M, Strzałka-Mrozik B, Grzybowski A, Romaniuk W, Mazurek U. Ophthalmic transplantology: posterior segment of the eye--part II. Med Sci Monit 2012; 18:RA97-103. [PMID: 22648265 PMCID: PMC3560715 DOI: 10.12659/msm.882868] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Background Transplants of the retina are among the new strategies being used in the treatment of genetic and degenerative macular diseases. Moreover, various cell cultures are being tested to treat retinal disorders. Material/Methods Literature dated from 2004 to 2011 was comprehensively examined via Medline and PubMed searches for the following terms: auto-, homo-, heterologous transplantation, retina, stem cells, cultivated cells. Results Tissue and cell therapy of retinal diseases are reviewed, including full-thickness retina/retinal pigment epithelium (RPE)/choroid graft; full and partial thickness RPE/choroid complex grafts; RPE/Bruch membrane complex graft; and RPE, iris pigment epithelium and stem cell grafts. Recommendations for transplants, as well as the benefits and weaknesses of specific techniques in retina transplants, are discussed. Conclusions Auto- and allogenic transplants of a full or partial thickness retina/RPE/Bruch membrane/choroid complex represent an alternative treatment offered to patients with some macular diseases. Stem cell transplantation to reconstruct and regenerate the macula requires further biomolecular and animal research studies.
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Affiliation(s)
- Małgorzata Nita
- Domestic and Specialized Medicine Centre Dilmed, Katowice, Poland
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9
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Léveillard T, Sahel JA. Rod-derived cone viability factor for treating blinding diseases: from clinic to redox signaling. Sci Transl Med 2010; 2:26ps16. [PMID: 20375363 DOI: 10.1126/scitranslmed.3000866] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The identification of one mechanism that causes vision loss in inherited degenerative retinal disorders revealed a new signaling molecule that represents a potential therapy for these currently untreatable diseases. This protein, called rod-derived cone viability factor (RdCVF), maintains the function and consequently the viability of cone photoreceptor cells in the retina; mice that lack this factor exhibit a progressive loss of photoreceptor cells. The gene encoding RdCVF also encodes, by differential splicing, a second product that has characteristics of a thioredoxin-like enzyme and protects both photoreceptor cells and, more specifically, its interacting protein partner, the tau protein, against oxidative damage. This signaling pathway potentially links environmental insults to an endogenous neuroprotective response.
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Affiliation(s)
- Thierry Léveillard
- Department of Genetics, Institut de la Vision, INSERM, UPMC University of Paris 06, UMR-S 968, CNRS 7210, Paris F-75012, France.
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10
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Abstract
PURPOSE OF REVIEW This review will discuss how recent advances with induced pluripotent stem (iPS) cells have brought the science of stem cell biology much closer to clinical application for patients with retinal degeneration. RECENT FINDINGS The ability to generate embryonic stem cells by reprogramming DNA taken from adult cells was demonstrated by the cloning of Dolly, the sheep, by somatic cell nuclear transfer, over 10 years ago. Recently, it has been shown that adult cells can be reprogrammed directly, without the need for a surrogate oocyte, through the generation of iPS cells. The method of reprogramming has since been optimized to avoid the use of retroviruses, making the process considerably safer. Last year, human iPS cells were isolated from an 80-year-old patient with neurodegenerative disease and differentiated into neurons in vitro. SUMMARY For stem cell therapies, the retina has the optimal combination of ease of surgical access, combined with an ability to observe transplanted cells directly through the clear ocular media. The question now is which retinal diseases are most appropriate targets for clinical trials using iPS cell approaches.
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Affiliation(s)
| | - Edward Lee
- Vitreoretinal Service, Moorfields Eye Hospital
- Moorfields UCL Institute of Ophthalmology NIHR Biomedical Research Centre
| | - Robert E MacLaren
- Vitreoretinal Service, Moorfields Eye Hospital
- Moorfields UCL Institute of Ophthalmology NIHR Biomedical Research Centre
- Nuffield Laboratory of Ophthalmology University of Oxford and Oxford Eye Hospital
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11
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Dutt K, Cao Y. Engineering retina from human retinal progenitors (cell lines). Tissue Eng Part A 2009; 15:1401-13. [PMID: 19113950 DOI: 10.1089/ten.tea.2007.0358] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Retinal degeneration resulting in the loss of photoreceptors is the leading cause of blindness. Several therapeutic protocols are under consideration for treatment of this disease. Tissue replacement is one such strategy currently being explored. However, availability of tissues for transplant poses a major obstacle. Another strategy with great potential is the use of adult stem cells, which could be expanded in culture and then utilized to engineer retinal tissue. In this study, we have explored a spontaneously immortalized human retinal progenitor cell line for its potential in retinal engineering using rotary cultures to generate three-dimensional (3D) structures. Retinal progenitors cultured alone or cocultured with retinal pigment epithelial cells form aggregates. The aggregate size increases between days 1 and 10. The cells grown as a 3D culture rotary system, which promotes cell-cell interaction, retain a spectrum of differentiation capability. Photoreceptor differentiation in these cultures is confirmed by significant upregulation of rhodopsin and AaNat, an enzyme implicated in melatonin synthesis (immunohistochemistry and Western blot analysis). Photoreceptor induction and differentiation is further attested to by the upregulation of rod transcription factor Nrl, Nr(2)e(3), expression of interstitial retinal binding protein, and rhodopsin kinase by reverse transcription-polymerase chain reaction. Differentiation toward other cell lineages is confirmed by the expression of tyrosine hydroxylase in amacrine cells, thy 1.1 expression in ganglion cells and calbindin, and GNB3 expression in cone cells. The capability of retinal progenitors to give rise to several retinal cell types when grown as aggregated cells in rotary culture offers hope that progenitor stem cells under appropriate culture conditions will be valuable to engineer retinal constructs, which could be further tested for their transplant potential. The fidelity with which this multipotential cell line retains its capacity to differentiate into multiple cell types holds great promise for the use of tissue-specific adult stem cells for therapy.
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Affiliation(s)
- Kamla Dutt
- Department of Pathology, Morehouse School of Medicine, Atlanta, Georgia 30310-1495, USA.
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12
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Rudolph G, Preising M, Kalpadakis P, Haritoglou C, Lang GE, Lorenz B. Phenotypic variability in three carriers from a family with choroideremia and a frameshift mutation 1388delCCinsG in the REP-1 gene. Ophthalmic Genet 2009; 24:203-14. [PMID: 14566650 DOI: 10.1076/opge.24.4.203.17232] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE To perform genotype-phenotype correlations in a family with choroideremia. METHODS A three-generation family with two affected males and five carriers was the subject of the study. Molecular genetic analysis using single-strand conformation polymorphism analysis (SSCP) was conducted in all subjects, while electroretinography (ERG), multifocal ERG (mfERG), scanning laser ophthalmoscope microperimetry (SLO perimetry), fluorescein angiography, and Arden contrast color testing were performed in one male and three carriers. RESULTS The findings in the affected male were typical for advanced choroideremia. The three carriers demonstrated a variable clinical phenotype including reduction of visual acuity and ERG and angiographic changes in one. Molecular genetic analysis revealed a functional null mutation (1388delCCinsG) in the REP-1 gene. CONCLUSIONS A severe retinal pathology was found in the affected male, indicating that the 1388delCCinsG is a severe mutation. Varying phenotypes were present in the three carriers examined. The phenotype in carriers has been explained by random X-inactivation with varying expression of the inactivated and activated gene copy inside the same cell of both the retinal pigment epithelium and the rods. This thesis is in agreement with the clinical data obtained here.
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Affiliation(s)
- Günther Rudolph
- Kooperationsgruppe Ophthalmogenetik der LMU und GSF University Eye Hospital, LMU, München, Germany.
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Sancho-Pelluz J, Arango-Gonzalez B, Kustermann S, Romero FJ, van Veen T, Zrenner E, Ekström P, Paquet-Durand F. Photoreceptor cell death mechanisms in inherited retinal degeneration. Mol Neurobiol 2008; 38:253-69. [PMID: 18982459 DOI: 10.1007/s12035-008-8045-9] [Citation(s) in RCA: 210] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Accepted: 10/16/2008] [Indexed: 02/24/2023]
Abstract
Photoreceptor cell death is the major hallmark of a group of human inherited retinal degenerations commonly referred to as retinitis pigmentosa (RP). Although the causative genetic mutations are often known, the mechanisms leading to photoreceptor degeneration remain poorly defined. Previous research work has focused on apoptosis, but recent evidence suggests that photoreceptor cell death may result primarily from non-apoptotic mechanisms independently of AP1 or p53 transcription factor activity, Bcl proteins, caspases, or cytochrome c release. This review briefly describes some animal models used for studies of retinal degeneration, with particular focus on the rd1 mouse. After outlining the major features of different cell death mechanisms in general, we then compare them with results obtained in retinal degeneration models, where photoreceptor cell death appears to be governed by, among other things, changes in cyclic nucleotide metabolism, downregulation of the transcription factor CREB, and excessive activation of calpain and PARP. Based on recent experimental evidence, we propose a putative non-apoptotic molecular pathway for photoreceptor cell death in the rd1 retina. The notion that inherited photoreceptor cell death is driven by non-apoptotic mechanisms may provide new ideas for future treatment of RP.
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Affiliation(s)
- Javier Sancho-Pelluz
- Institute for Ophthalmic Research, University of Tübingen, Centre for Ophthalmology, Röntgenweg 11, 72076, Tübingen, Germany
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Nishiwaki Y, Komori A, Sagara H, Suzuki E, Manabe T, Hosoya T, Nojima Y, Wada H, Tanaka H, Okamoto H, Masai I. Mutation of cGMP phosphodiesterase 6alpha'-subunit gene causes progressive degeneration of cone photoreceptors in zebrafish. Mech Dev 2008; 125:932-46. [PMID: 18824093 DOI: 10.1016/j.mod.2008.09.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Revised: 09/02/2008] [Accepted: 09/04/2008] [Indexed: 11/25/2022]
Abstract
In mammals, the blockade of the phototransduction cascade causes loss of vision and, in some cases, degeneration of photoreceptors. However, the molecular mechanisms that link phototransduction with photoreceptor degeneration remain to be elucidated. Here, we report that a mutation in the gene encoding a central effector of the phototransduction cascade, cGMP phosphodiesterase 6alpha'-subunit (PDE6alpha'), affects not only the vision but also the survival of cone photoreceptors in zebrafish. We isolated a zebrafish mutant, called eclipse (els), which shows no visual behavior such as optokinetic response (OKR). The cloning of the els mutant gene revealed that a missense mutation occurred in the pde6alpha' gene, resulting in a change in a conserved amino acid. The PDE6 expressed in rod photoreceptors is a heterotetramer comprising two closely related similar hydrolytic alpha and beta subunits and two identical inhibitory gamma subunits, while the PDE6 expressed in cone photoreceptors consists of two homodimers of alpha' subunits, each with gamma subunits. The els mutant displays no visual response to bright light, where cones are active, but shows relatively normal OKR to dim light, where only rods function, suggesting that only the cone-specific phototransduction pathway is disrupted in the els mutant. Furthermore, in the els mutant, cones are selectively eliminated but rods are retained at the adult stage, suggesting that cones undergo a progressive degeneration in the els mutant retinas. Taken together, these data suggest that PDE6alpha' activity is important for the survival of cones in zebrafish.
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Affiliation(s)
- Yuko Nishiwaki
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Promotion Corporation, Suzaki 12-2, Uruma, Okinawa 904-2234, Japan
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15
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Lorentz O, Sahel J, Mohand-Saïd S, Leveillard T. Cone survival: identification of RdCVF. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 572:315-9. [PMID: 17249590 DOI: 10.1007/0-387-32442-9_44] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Affiliation(s)
- Olivier Lorentz
- INSERM U592, Bâtiment Kourilsky, Hôpital St-Antoine, 184 rue du Faubourg St-Antoine, 75571 Paris
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16
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Rothermel A, Biedermann T, Weigel W, Kurz R, Rüffer M, Layer PG, Robitzki AA. Artificial design of three-dimensional retina-like tissue from dissociated cells of the mammalian retina by rotation-mediated cell aggregation. ACTA ACUST UNITED AC 2006; 11:1749-56. [PMID: 16411820 DOI: 10.1089/ten.2005.11.1749] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The goal of this study was to establish a reliable three-dimensional culture system for the mammalian retina that allows the analysis of retinal function and dysfunction. To produce three-dimensional retinal tissues in vitro, dissociated retinal cells of neonatal rats were maintained in culture dishes on a self-made orbital shaker. On the basis of well-defined rotation conditions, dissociated free-floating cells reaggregate in the center of the culture dish to form a multicellular cluster. Subsequently, cells begin to proliferate, whereby they form spherelike retinal tissues that grow to a size of 180-210 microm. Immunohistochemical characterization of mature retinal spheres revealed the presence of ganglion cells, amacrine cells, Müller cells, and rod photoreceptors, which are arranged in different retina-like layers. Although a small number of cells undergo programmed cell death, retinal spheres remain viable for at least 35 days in culture as revealed by fluorescein diacetate and TUNEL staining. Because most biological processes involved in tissue organization such as proliferation, differentiation, apoptosis, and survival are also observable in retinal spheres, the presented novel mammalian three-dimensional culture system is not only an outstanding model for basic research but may also be of great benefit for stem cell tissue engineering and the pharmaceutical industry.
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Affiliation(s)
- Andrée Rothermel
- Biotechnological-Biomedical Center, Department of Molecular Biological-Biochemical Processing Technology, University of Leipzig, Leipzig, Germany.
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17
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Zeiss CJ, Allore HG, Towle V, Tao W. CNTF induces dose-dependent alterations in retinal morphology in normal and rcd-1 canine retina. Exp Eye Res 2006; 82:395-404. [PMID: 16143329 DOI: 10.1016/j.exer.2005.07.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2005] [Revised: 07/11/2005] [Accepted: 07/20/2005] [Indexed: 10/25/2022]
Abstract
Ciliary neurotrophic factor (CNTF) provides morphologic preservation of rods in several animal models of retinitis pigmentosa (RP). However, CNTF may alter photoreceptor morphology and rod photoreceptor differentiation in vitro, as well as affecting normal retinal electrophysiology. In addition, the capacity of CNTF to support other cell types affected secondarily in RP (cones and ganglion cells) is unclear. The purposes of this study were to examine the effects of CNTF upon a canine model of RP, the rod-cone degeneration (rcd-1) dog. Archival tissue from a previous study assessing the capacity of CNTF to rescue photoreceptors in rcd-1 dogs was used. One eye was treated for 7 weeks before being explanted. The contralateral eye was untreated. A total of 23 rcd-1 dogs and seven control dogs (four untreated and three CNTF-treated) were used. Morphometric data describing outer and inner nuclear layer thickness, inner retinal thickness, cones and ganglion cells were collected at nine evenly spaced points along each retina and analysed using a mixed effects model. Immunohistochemistry was performed on a subset of 11 dogs for expression of rhodopsin, human cone arrestin (hCAR) and recoverin. CNTF protected the outer nuclear layer and increased inner retinal thickness in a dose-dependent manner (both were maximal at CNTF doses of 1-6 ng day-1). Significant cone loss or reduction of inner nuclear layer width in rcd-1 did not occur in this model, therefore we were unable to assess the protective effect of CNTF upon these parameters. CNTF did not afford significant ganglion cell protection. CNTF induced morphologic changes in rods and ganglion cells, as well as reducing expression of hCAR and rhodopsin, but not recoverin. The dose of CNTF which provided optimal outer nuclear layer protection also resulted in several other effects, including altered ganglion cell morphology, increased thickness of the entire retina, and reduced expression of some phototransduction proteins. These changes were more marked in rcd-1 retinas than in wild-type retinas. This implies that the consequences of CNTF treatment may be substantially influenced by the cellular context into which it is introduced.
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Affiliation(s)
- Caroline J Zeiss
- Section of Comparative Medicine, Yale University School of Medicine, 375 Congress Ave, New Haven, CT 06510, USA.
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18
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Retinal Pigment Epithelium and Photoreceptor Transplantation Frontiers. Retina 2006. [DOI: 10.1016/b978-0-323-02598-0.50159-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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19
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Léveillard T, Mohand-Saïd S, Poch O, Sahel JA. [Rod-derived cone viability factor: a clue for therapy of retinitis pigmentosa?]. Med Sci (Paris) 2005; 21:22-4. [PMID: 15639013 DOI: 10.1051/medsci/200521122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Girman SV, Wang S, Lund RD. Time course of deterioration of rod and cone function in RCS rat and the effects of subretinal cell grafting: a light- and dark-adaptation study. Vision Res 2005; 45:343-54. [PMID: 15607350 DOI: 10.1016/j.visres.2004.08.023] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2003] [Revised: 08/17/2004] [Indexed: 11/28/2022]
Abstract
To examine how rod and cone function are differentially affected during retinal degeneration, and after subretinal cell grafting, we obtained light- and dark-adaptation curves by recording threshold multiunit responses from the superior colliculus of anesthetized rats. Unoperated RCS dystrophic and non-dystrophic rats were used and the effects of subretinal grafting in dystrophic rats of cells known to limit photoreceptor degeneration were examined. The adaptation curves showed that rod function was severely compromised in unoperated dystrophic RCS rats at low luminance levels, even as early as 21 days of age and that cone thresholds became gradually elevated over time. While cell transplantation preserved both rod and cone photoreceptors, rod function did not recover, although further deterioration of cone threshold responses was prevented. This raises concern that measures of outer nuclear layer thickness may not in themselves be an accurate measure of visual capabilities and efficacy of a restoration strategy.
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Affiliation(s)
- S V Girman
- Moran Eye Center, University of Utah Health Sciences Center, 50 North Medical Drive, Salt Lake City, UT 84132, USA.
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21
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Pinilla I, Lund RD, Sauvé Y. Cone function studied with flicker electroretinogram during progressive retinal degeneration in RCS rats. Exp Eye Res 2005; 80:51-9. [PMID: 15652526 DOI: 10.1016/j.exer.2004.08.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Accepted: 08/09/2004] [Indexed: 02/05/2023]
Abstract
The Royal College of Surgeons (RCS) rat has a primary defect in retinal pigment epithelial cells that leads to the progressive loss of photoreceptors and central visual responsiveness. While most rods are lost by 90 days of age (P90), cones degenerate more slowly, and can be detected anatomically up to 2 years of age, despite massive neuronal death and retinal remodelling. To examine how this progressive degenerative process impacts on cone function, we recorded the electroretingram to white light flashes (1.37 log cd s m(-2)) presented at frequencies ranging from 3 to 50 Hz, under light adapted conditions (29.8 cd m(-2)). Pigmented dystrophic and congenic non-dystrophic RCS rats aged from 18 to 300 days were studied. In all responsive animals at all ages, maximal amplitudes were obtained at 3 Hz. In both non-dystrophic and dystrophic rats, there was an increase from P18 to P21 in response amplitude and critical fusion frequency. After P21, these two parameters declined progressively with age in dystrophic rats. Other changes included prolongation in latency, which was first detected prior to the initiation of amplitude reduction. While phase shifts were also detected in dystrophic RCS rats, they appeared at later degenerative stages. The latest age at which responses could be elicited in dystrophic rats was at P200, with positive waves being replaced by negative deflections. The effect of increments in the intensity of background illumination was tested at P50 in both groups. This caused a diminution in flicker response amplitude and critical fusion frequencies in non-dystrophics, while in dystrophic animals, response amplitudes were reduced only at low frequencies and critical fusion frequencies were unaltered. In conclusion, although dystrophic RCS rats undergo a progressive decline in cone function with age, the flicker responsiveness at P21 is comparable to that of non-dystrophic congenic rats, suggesting normal developmental maturation of the cone system in this animal model of retinal degeneration. Flicker responses can be recorded up to P200, at which point the retina has undergone severe regressive and reactive changes in its connectivity patterns. The fact that responses at this age consist of solely negative deflections might be a reflection of the highly pathological state of the retina.
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Affiliation(s)
- I Pinilla
- Moran Eye Center, Ophthalmology and Visual Sciences, University of Utah, 75 North Medical Drive, Salt Lake City, UT 84132, USA
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22
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Goldsmith P, Baier H, Harris WA. Two zebrafish mutants, ebony and ivory, uncover benefits of neighborhood on photoreceptor survival. ACTA ACUST UNITED AC 2004; 57:235-45. [PMID: 14608660 DOI: 10.1002/neu.10274] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Zebrafish offer a tractable system for the study of retinal development and degeneration, to provide insights into human retinal degeneration. We have begun to dissect the question of neighborhood effects on photoreceptor differentiation and survival through the isolation and characterization of mutants with retinal degeneration. We describe two mutants, ebony and ivory, isolated through a behavioral screen for blind mutants induced by ethyl nitrosourea mutagenesis. Chimeric analysis was conducted to attempt to rescue the photoreceptor degeneration. In ebony, the photoreceptor cell death was both cell autonomous and nonautonomous in nature, whilst the photoreceptor cell death was strikingly nonautonomous in ivory. The rescue at a distance is in keeping with a putative diffusible survival factor. We propose a density-dependent nonautonomous neighborhood effect to explain these findings.
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Affiliation(s)
- Paul Goldsmith
- Department of Anatomy, University of Cambridge, Downing Site, Cambridge, CB2 3DY, United Kingdom
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Gupta N, Brown KE, Milam AH. Activated microglia in human retinitis pigmentosa, late-onset retinal degeneration, and age-related macular degeneration. Exp Eye Res 2003; 76:463-71. [PMID: 12634111 DOI: 10.1016/s0014-4835(02)00332-9] [Citation(s) in RCA: 414] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Many gaps exist in our knowledge of human retinal microglia in health and disease. We address the hypothesis that primary death of rod photoreceptors leads to activation of resident microglia in human retinas with retinitis pigmentosa (RP), late-onset retinal degeneration (L-ORD), or age-related macular degeneration (AMD). Regions of ongoing photoreceptor cell death were studied by immunocytochemistry with microglia- and other retinal cell-specific markers. In normal human retinas, quiescent microglia were small, stellate cells associated with inner retinal blood vessels. In retinas with RP, L-ORD, or AMD, numerous activated microglia were present in the outer nuclear layer in regions of ongoing rod cell death. These microglia were enlarged, amoeboid cells that contained rhodopsin-positive cytoplasmic inclusions. We conclude that activated microglia migrate to the outer nuclear layer and remove rod cell debris. In other central nervous system diseases such as stroke, activated microglia phagocytose debris from the primary injury and also secrete molecules that kill nearby normal neurons. By analogy with these diseases, we suggest that microglia activated by primary rod cell death may kill adjacent photoreceptors. Activated microglia may be a missing link in understanding why initial rod cell death in the human diseases RP, L-ORD, and AMD leads to death of the cones that are critical for high acuity daytime vision.
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Affiliation(s)
- Nisha Gupta
- Scheie Eye Institute, 51 North 39th Street, Philadelphia, PA 19104, USA
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24
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Ayyagari R, Demirci FY, Liu J, Bingham EL, Stringham H, Kakuk LE, Boehnke M, Gorin MB, Richards JE, Sieving PA. X-linked recessive atrophic macular degeneration from RPGR mutation. Genomics 2002; 80:166-71. [PMID: 12160730 DOI: 10.1006/geno.2002.6815] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We mapped a new X-linked recessive atrophic macular degeneration locus to Xp21.1-p11.4 and show allelic involvement of the gene RPGR, which normally causes severe peripheral retinal degeneration leading to global blindness. Ten affected males whom we examined had primarily macular atrophy causing progressive loss of visual acuity with minimal peripheral visual impairment. One additional male showed extensive macular degeneration plus peripheral loss of retinal pigment epithelium and choriocapillaries. Full-field electroretinograms (ERGs) showed normal cone and rod responses in some affected males despite advanced macular degeneration, emphasizing the dissociation of atrophic macular degeneration from generalized cone degenerations, including X-linked cone dystrophy (COD1). The RPGR gene nonsense mutation G-->T at open reading frame (ORF)15+1164 cosegregated with the disease and may create a donor splice site. Identification of an RPGR mutation in atrophic maculardegeneration expands the phenotypic range associated with this gene and provides a new tool for the dissection of the relationship between clinically different retinal pathologies.
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Affiliation(s)
- Radha Ayyagari
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, 48105, USA
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