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Tworak A, Kolesnikov AV, Hong JD, Choi EH, Luu JC, Palczewska G, Dong Z, Lewandowski D, Brooks MJ, Campello L, Swaroop A, Kiser PD, Kefalov VJ, Palczewski K. Rapid RGR-dependent visual pigment recycling is mediated by the RPE and specialized Müller glia. Cell Rep 2023; 42:112982. [PMID: 37585292 PMCID: PMC10530494 DOI: 10.1016/j.celrep.2023.112982] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/14/2023] [Accepted: 07/29/2023] [Indexed: 08/18/2023] Open
Abstract
In daylight, demand for visual chromophore (11-cis-retinal) exceeds supply by the classical visual cycle. This shortfall is compensated, in part, by the retinal G-protein-coupled receptor (RGR) photoisomerase, which is expressed in both the retinal pigment epithelium (RPE) and in Müller cells. The relative contributions of these two cellular pools of RGR to the maintenance of photoreceptor light responses are not known. Here, we use a cell-specific gene reactivation approach to elucidate the kinetics of RGR-mediated recovery of photoreceptor responses following light exposure. Electroretinographic measurements in mice with RGR expression limited to either cell type reveal that the RPE and a specialized subset of Müller glia contribute both to scotopic and photopic function. We demonstrate that 11-cis-retinal formed through photoisomerization is rapidly hydrolyzed, consistent with its role in a rapid visual pigment regeneration process. Our study shows that RGR provides a pan-retinal sink for all-trans-retinal released under sustained light conditions and supports rapid chromophore regeneration through the photic visual cycle.
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Affiliation(s)
- Aleksander Tworak
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA.
| | - Alexander V Kolesnikov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - John D Hong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Jennings C Luu
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Grazyna Palczewska
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Polgenix, Inc., Department of Medical Devices, Cleveland, OH 44106, USA
| | - Zhiqian Dong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Dominik Lewandowski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Matthew J Brooks
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Laura Campello
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Philip D Kiser
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697, USA; Department of Clinical Pharmacy Practice, University of California, Irvine, Irvine, CA 92697, USA; Research Service, VA Long Beach Healthcare System, Long Beach, CA 90822, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697, USA; Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697, USA.
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Cellular and Molecular Mechanisms of Pathogenesis Underlying Inherited Retinal Dystrophies. Biomolecules 2023; 13:biom13020271. [PMID: 36830640 PMCID: PMC9953031 DOI: 10.3390/biom13020271] [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: 12/21/2022] [Revised: 01/23/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
Inherited retinal dystrophies (IRDs) are congenital retinal degenerative diseases that have various inheritance patterns, including dominant, recessive, X-linked, and mitochondrial. These diseases are most often the result of defects in rod and/or cone photoreceptor and retinal pigment epithelium function, development, or both. The genes associated with these diseases, when mutated, produce altered protein products that have downstream effects in pathways critical to vision, including phototransduction, the visual cycle, photoreceptor development, cellular respiration, and retinal homeostasis. The aim of this manuscript is to provide a comprehensive review of the underlying molecular mechanisms of pathogenesis of IRDs by delving into many of the genes associated with IRD development, their protein products, and the pathways interrupted by genetic mutation.
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Vöcking O, Macias-Muñoz A, Jaeger SJ, Oakley TH. Deep Diversity: Extensive Variation in the Components of Complex Visual Systems across Animals. Cells 2022; 11:cells11243966. [PMID: 36552730 PMCID: PMC9776813 DOI: 10.3390/cells11243966] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/19/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
Understanding the molecular underpinnings of the evolution of complex (multi-part) systems is a fundamental topic in biology. One unanswered question is to what the extent do similar or different genes and regulatory interactions underlie similar complex systems across species? Animal eyes and phototransduction (light detection) are outstanding systems to investigate this question because some of the genetics underlying these traits are well characterized in model organisms. However, comparative studies using non-model organisms are also necessary to understand the diversity and evolution of these traits. Here, we compare the characteristics of photoreceptor cells, opsins, and phototransduction cascades in diverse taxa, with a particular focus on cnidarians. In contrast to the common theme of deep homology, whereby similar traits develop mainly using homologous genes, comparisons of visual systems, especially in non-model organisms, are beginning to highlight a "deep diversity" of underlying components, illustrating how variation can underlie similar complex systems across taxa. Although using candidate genes from model organisms across diversity was a good starting point to understand the evolution of complex systems, unbiased genome-wide comparisons and subsequent functional validation will be necessary to uncover unique genes that comprise the complex systems of non-model groups to better understand biodiversity and its evolution.
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Affiliation(s)
- Oliver Vöcking
- Department of Biology, University of Kentucky, Lexington, KY 40508, USA
| | - Aide Macias-Muñoz
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
| | - Stuart J. Jaeger
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
| | - Todd H. Oakley
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
- Correspondence:
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Ng ESY, Kady N, Hu J, Dave A, Jiang Z, Pei J, Gorin MB, Matynia A, Radu RA. Membrane Attack Complex Mediates Retinal Pigment Epithelium Cell Death in Stargardt Macular Degeneration. Cells 2022; 11:3462. [PMID: 36359858 PMCID: PMC9655712 DOI: 10.3390/cells11213462] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 10/28/2022] [Accepted: 10/30/2022] [Indexed: 08/22/2023] Open
Abstract
Recessive Stargardt disease (STGD1) is an inherited retinopathy caused by mutations in the ABCA4 gene. The ABCA4 protein is a phospholipid-retinoid flippase in the outer segments of photoreceptors and the internal membranes of retinal pigment epithelial (RPE) cells. Here, we show that RPE cells derived via induced pluripotent stem-cell from a molecularly and clinically diagnosed STGD1 patient exhibited reduced ABCA4 protein and diminished activity compared to a normal subject. Consequently, STGD1 RPE cells accumulated intracellular autofluorescence-lipofuscin and displayed increased complement C3 activity. The level of C3 inversely correlated with the level of CD46, an early negative regulator of the complement cascade. Persistent complement dysregulation led to deposition of the membrane attack complex on the surface of RPE cells, decrease in transepithelial resistance, and subsequent cell death. These findings are strong evidence of complement-mediated RPE cell damage in STGD1, in the absence of photoreceptors, caused by reduced CD46 regulatory protein.
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Affiliation(s)
- Eunice Sze Yin Ng
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, CA 90095, USA
- Molecular Cellular and Integrative Physiology Interdepartmental Program, University of California, Los Angeles, CA 90095, USA
| | - Nermin Kady
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, CA 90095, USA
- Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI 48109, USA
- Clinical Pathology Department, Faculty of Medicine, Mansoura University, Mansoura 35516, Egypt
| | - Jane Hu
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, CA 90095, USA
| | - Arpita Dave
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, CA 90095, USA
| | - Zhichun Jiang
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, CA 90095, USA
| | - Jacqueline Pei
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, CA 90095, USA
| | - Michael B. Gorin
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, CA 90095, USA
| | - Anna Matynia
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, CA 90095, USA
| | - Roxana A. Radu
- UCLA Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, CA 90095, USA
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Jiang X, Mahroo OA. Human retinal dark adaptation tracked in vivo with the electroretinogram: insights into processes underlying recovery of cone- and rod-mediated vision. J Physiol 2022; 600:4603-4621. [PMID: 35612091 PMCID: PMC9796346 DOI: 10.1113/jp283105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 05/04/2022] [Indexed: 01/02/2023] Open
Abstract
The substantial time taken for regaining visual sensitivity (dark adaptation) following bleaching exposures has been investigated for over a century. Psychophysical studies yielded the classic biphasic curve representing recovery of cone-driven and rod-driven vision. The electroretinogram (ERG) permits direct assessment of recovery at the level of the retina (photoreceptors, bipolar cells), with the first report over 70 years ago. Over the last two decades, ERG studies of dark adaptation have generated insights into underlying physiological processes. After large bleaches, rod photoreceptor circulating current, estimated from the rod-isolated bright-flash ERG a-wave, takes 30 min to recover, indicating that products of bleaching, thought to be free opsin (unbound to 11-cis-retinal), continue to activate phototransduction, shutting off rod circulating current. In contrast, cone current, assessed with cone-driven bright-flash ERG a-waves, recovers within 100 ms following similar exposures, suggesting that free opsin is less able to shut off cone current. The cone-driven dim-flash a-wave can be used to track recovery of cone photopigment, showing regeneration is 'rate-limited' rather than first order. Recoveries of the dim-flash ERG b-wave are consistent also with rate-limited rod photopigment regeneration (where free opsin, desensitising the visual system as an 'equivalent background', is removed by rate-limited delivery of 11-cis-retinal). These findings agree with psychophysical and retinal densitometry studies, although there are unexplained points of divergence. Post-bleach ERG recovery has been explored in age-related macular degeneration and in trials of visual cycle inhibitors for retinal diseases. ERG tracking of dark adaptation may prove useful in future clinical contexts.
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Affiliation(s)
- Xiaofan Jiang
- Institute of OphthalmologyUniversity College LondonLondonUK,Retinal and Genetics ServicesMoorfields Eye HospitalLondonUK,Section of OphthalmologyKing's College LondonLondonUK,Department of Twin Research and Genetic EpidemiologyKing's College London, St Thomas’ Hospital CampusLondonUK
| | - Omar A. Mahroo
- Institute of OphthalmologyUniversity College LondonLondonUK,Retinal and Genetics ServicesMoorfields Eye HospitalLondonUK,Section of OphthalmologyKing's College LondonLondonUK,Department of Twin Research and Genetic EpidemiologyKing's College London, St Thomas’ Hospital CampusLondonUK,PhysiologyDevelopment and NeuroscienceUniversity of CambridgeCambridgeUK
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Gühmann M, Porter ML, Bok MJ. The Gluopsins: Opsins without the Retinal Binding Lysine. Cells 2022; 11:cells11152441. [PMID: 35954284 PMCID: PMC9368030 DOI: 10.3390/cells11152441] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/23/2022] [Accepted: 07/28/2022] [Indexed: 12/14/2022] Open
Abstract
Opsins allow us to see. They are G-protein-coupled receptors and bind as ligand retinal, which is bound covalently to a lysine in the seventh transmembrane domain. This makes opsins light-sensitive. The lysine is so conserved that it is used to define a sequence as an opsin and thus phylogenetic opsin reconstructions discard any sequence without it. However, recently, opsins were found that function not only as photoreceptors but also as chemoreceptors. For chemoreception, the lysine is not needed. Therefore, we wondered: Do opsins exists that have lost this lysine during evolution? To find such opsins, we built an automatic pipeline for reconstructing a large-scale opsin phylogeny. The pipeline compiles and aligns sequences from public sources, reconstructs the phylogeny, prunes rogue sequences, and visualizes the resulting tree. Our final opsin phylogeny is the largest to date with 4956 opsins. Among them is a clade of 33 opsins that have the lysine replaced by glutamic acid. Thus, we call them gluopsins. The gluopsins are mainly dragonfly and butterfly opsins, closely related to the RGR-opsins and the retinochromes. Like those, they have a derived NPxxY motif. However, what their particular function is, remains to be seen.
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Affiliation(s)
- Martin Gühmann
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
- Correspondence:
| | - Megan L. Porter
- Department of Biology, University of Hawai’i at Mānoa, Honolulu, HI 96822, USA
| | - Michael J. Bok
- Lund Vision Group, Department of Biology, University of Lund, 223 62 Lund, Sweden
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Mermeklieva E, Kamenarova K, Mihova K, Shakola F, Kaneva R. A rare case of RGR/CDHR1 haplotype identified in Bulgarian patient with cone-rod dystrophy. Ophthalmic Genet 2021; 42:747-752. [PMID: 34229535 DOI: 10.1080/13816810.2021.1946700] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
AIM To present a rare clinical case of CDHR1-related retinopathy with cone and rod involvementconfirmed clinically, electrophysiologically and genetically as a cone-rod dystrophy. MATERIAL AND METHODS A 26-year-old woman underwent detailed ophthalmic examinationincluding fundus photography, full-field and multifocal electroretinography, visual field testing, optical coherence tomography and fluorescein angiography, which established the clinical diagnosis. Next-generation sequencing of a custom panel including 140 of the most common genes for inherited retinal degenerations was used for mutation screening. RESULTS The symptoms onset was two years ago included gradual loss of vision and photophobia. The clinical findings were reduced visual acuity, central and peripheral scotomas, sporadic pigmentary cells localized mainly in the peripheral retina, a thinner retina in the macula and peripherally, moderate retinal vessels attenuation and reduced cone and rod ERG responses. The genetic analysisfound that the patient was homozygous for two already reported mutations: RGR-c.196A>C (p.Ser66Arg) variant and a co-segregating frame-shift deletion in CDHR1-c.2522_2528delTCTCTGA (p.Ile841Serfs119*). Segregation analysis showed that the two mutations were transmitted by the asymptomatic heterozygous parents. CONCLUSION The rare haplotype of RGR mutation co-segregating incis- with CDHR1 mutation in our patient has been previously described in Albanian patients with recessive retinal dystrophy. Our findings add further support to the hypothesis of a common ancestral haplotype spread in the Balkan population. The comprehensive clinical, electrophysiological and genetic testing of patients with rare hereditary retinal dystrophies is essential for the correct diagnosis and the choice of potential novel therapies.
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Affiliation(s)
- Elena Mermeklieva
- Clinic of Оphthalmology, "Lozenetz" University Hospital, Medical Faculty, Sofia University "St. Kliment Ohridski", Sofia, Bulgaria
| | - Kunka Kamenarova
- Molecular Medicine Center, Department of Medical Chemistry and Biochemistry, Medical Faculty, Medical University - Sofia, Sofia, Bulgaria
| | - Kalina Mihova
- Molecular Medicine Center, Department of Medical Chemistry and Biochemistry, Medical Faculty, Medical University - Sofia, Sofia, Bulgaria
| | - Felitsiya Shakola
- Molecular Medicine Center, Department of Medical Chemistry and Biochemistry, Medical Faculty, Medical University - Sofia, Sofia, Bulgaria
| | - Radka Kaneva
- Molecular Medicine Center, Department of Medical Chemistry and Biochemistry, Medical Faculty, Medical University - Sofia, Sofia, Bulgaria
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Constable PA, Kapoor G. Is white the right light for the clinical electrooculogram? Doc Ophthalmol 2021; 143:297-304. [PMID: 34160736 DOI: 10.1007/s10633-021-09845-9] [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: 04/13/2021] [Accepted: 06/14/2021] [Indexed: 11/30/2022]
Abstract
PURPOSE To investigate if a lower luminance monochromatic LED stimulus could be used as an alternative to a high luminance white light for the clinical electrooculogram. METHODS Clinical electrooculograms were recorded in color normal participants (N = 23) aged 22.6 ± 1.2 years, 7 male and 16 female using the standard 100 cd.m-2 white illuminant and four monochromatic LEDs with peak wavelengths of 448, 534, 596 and 634 nm at 30 cd.m-2. Pupils were dilated and there was a 30 cd.m-2pre-adaptation to white light for 2 min followed by 15 min dark adaptation and 20 min recording in the light stimulus using a Ganzfeld stimulator. RESULTS The normalized LP:DTratio for the short wavelength LED (448 nm) was equivalent in amplitude and timing to the ISCEV standard EOG (p = .99). The LP:DTratio for the white (100 cd.m-2) and 448 nm (30 cd.m-2) were (median ± SEM): 2.49 ± .11 and 2.47 ± .11. The time to light-rise peak was also equivalent being 9.0 ± .2 and 8.0 ± .4 min (p = .54). CONCLUSIONS Consideration may be given to using a short wavelength monochromatic stimulus that is more comfortable for the subject than the current 100 cd.m-2 illuminant.
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Affiliation(s)
- Paul A Constable
- Caring Futures Institute, College of Nursing and Health Sciences, Flinders University, PO Box 2100, Adelaide, SA, 5001, Australia.
| | - Garima Kapoor
- College of Medicine and Public Health, Flinders University, Adelaide, Australia
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Bao X, Zhang Z, Guo Y, Buser C, Kochounian H, Wu N, Li X, He S, Sun B, Ross-Cisneros FN, Sadun AA, Huang L, Zhao M, Fong HKW. Human RGR Gene and Associated Features of Age-Related Macular Degeneration in Models of Retina-Choriocapillaris Atrophy. THE AMERICAN JOURNAL OF PATHOLOGY 2021; 191:1454-1473. [PMID: 34022179 DOI: 10.1016/j.ajpath.2021.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 04/16/2021] [Accepted: 05/05/2021] [Indexed: 01/28/2023]
Abstract
Age-related macular degeneration (AMD) is a progressive eye disease and the most common cause of blindness among the elderly. AMD is characterized by early atrophy of the choriocapillaris and retinal pigment epithelium (RPE). Although AMD is a multifactorial disease with many environmental and genetic risk factors, a hallmark of the disease is the origination of extracellular deposits, or drusen, between the RPE and Bruch membrane. Human retinal G-protein-coupled receptor (RGR) gene generates an exon-skipping splice variant of RGR-opsin (RGR-d; NP_001012740) that is a persistent component of small and large drusen. Herein, the findings show that abnormal RGR proteins, including RGR-d, are pathogenic in an animal retina with degeneration of the choriocapillaris, RPE, and photoreceptors. A frameshift truncating mutation resulted in severe retinal degeneration with a continuous band of basal deposits along the Bruch membrane. RGR-d produced less severe disease with choriocapillaris and RPE atrophy, including focal accumulation of abnormal RGR-d protein at the basal boundary of the RPE. Degeneration of the choriocapillaris was marked by a decrease in endothelial CD31 protein and choriocapillaris breakdown at the ultrastructural level. Fundus lesions with patchy depigmentation were characteristic of old RGR-d mice. RGR-d was mislocalized in cultured cells and caused a strong cell growth defect. These results uphold the notion of a potential hidden link between AMD and a high-frequency RGR allele.
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Affiliation(s)
- Xuan Bao
- Department of Ophthalmology, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Peking University People's Hospital, Beijing, China; Department of Ophthalmology, Keck School of Medicine of USC, Los Angeles, California
| | - Zhaoxia Zhang
- Department of Ophthalmology, Keck School of Medicine of USC, Los Angeles, California; Shanxi Eye Hospital, Taiyuan, China
| | - Yanjiang Guo
- Department of Ophthalmology, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Peking University People's Hospital, Beijing, China
| | | | | | - Nancy Wu
- Norris Cancer Center, Keck School of Medicine of University of Southern California, Los Angeles, California
| | - Xiaohua Li
- Henan Eye Institute, Henan Provincial People's Hospital, Henan, China
| | - Shikun He
- Department of Pathology, Keck School of Medicine of USC, Los Angeles, California
| | - Bin Sun
- Shanxi Eye Hospital, Taiyuan, China
| | | | - Alfredo A Sadun
- Doheny Eye Institute, Los Angeles, California; Department of Ophthalmology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California
| | - Lvzhen Huang
- Department of Ophthalmology, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Peking University People's Hospital, Beijing, China
| | - Mingwei Zhao
- Department of Ophthalmology, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Peking University People's Hospital, Beijing, China.
| | - Henry K W Fong
- Department of Ophthalmology, Keck School of Medicine of USC, Los Angeles, California; University of Southern California Roski Eye Institute, Los Angeles, California; Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, California.
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Rod Photoreceptors Avoid Saturation in Bright Light by the Movement of the G Protein Transducin. J Neurosci 2021; 41:3320-3330. [PMID: 33593858 DOI: 10.1523/jneurosci.2817-20.2021] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/21/2021] [Accepted: 01/26/2021] [Indexed: 11/21/2022] Open
Abstract
Rod photoreceptors can be saturated by exposure to bright background light, so that no flash superimposed on the background can elicit a detectable response. This phenomenon, called increment saturation, was first demonstrated psychophysically by Aguilar and Stiles and has since been shown in many studies to occur in single rods. Recent experiments indicate, however, that rods may be able to avoid saturation under some conditions of illumination. We now show in ex vivo electroretinogram and single-cell recordings that in continuous and prolonged exposure even to very bright light, the rods of mice from both sexes recover as much as 15% of their dark current and that responses can persist for hours. In parallel to recovery of outer segment current is an ∼10-fold increase in the sensitivity of rod photoresponses. This recovery is decreased in transgenic mice with reduced light-dependent translocation of the G protein transducin. The reduction in outer-segment transducin together with a novel mechanism of visual-pigment regeneration within the rod itself enable rods to remain responsive over the whole of the physiological range of vision. In this way, rods are able to avoid an extended period of transduction channel closure, which is known to cause photoreceptor degeneration.SIGNIFICANCE STATEMENT Rods are initially saturated in bright light so that no flash superimposed on the background can elicit a detectable response. Frederiksen and colleagues show in whole retina and single-cell recordings that, if the background light is prolonged, rods slowly recover and can continue to produce significant responses over the entire physiological range of vision. Response recovery occurs by translocation of the G protein transducin from the rod outer to the inner segment, together with a novel mechanism of visual-pigment regeneration within the rod itself. Avoidance of saturation in bright light may be one of the principal mechanisms the retina uses to keep rod outer-segment channels from ever closing for too long a time, which is known to produce photoreceptor degeneration.
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Upton BA, Díaz NM, Gordon SA, Van Gelder RN, Buhr ED, Lang RA. Evolutionary Constraint on Visual and Nonvisual Mammalian Opsins. J Biol Rhythms 2021; 36:109-126. [PMID: 33765865 PMCID: PMC8058843 DOI: 10.1177/0748730421999870] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Animals have evolved light-sensitive G protein-coupled receptors, known as opsins, to detect coherent and ambient light for visual and nonvisual functions. These opsins have evolved to satisfy the particular lighting niches of the organisms that express them. While many unique patterns of evolution have been identified in mammals for rod and cone opsins, far less is known about the atypical mammalian opsins. Using genomic data from over 400 mammalian species from 22 orders, unique patterns of evolution for each mammalian opsins were identified, including photoisomerases, RGR-opsin (RGR) and peropsin (RRH), as well as atypical opsins, encephalopsin (OPN3), melanopsin (OPN4), and neuropsin (OPN5). The results demonstrate that OPN5 and rhodopsin show extreme conservation across all mammalian lineages. The cone opsins, SWS1 and LWS, and the nonvisual opsins, OPN3 and RRH, demonstrate a moderate degree of sequence conservation relative to other opsins, with some instances of lineage-specific gene loss. Finally, the photoisomerase, RGR, and the best-studied atypical opsin, OPN4, have high sequence diversity within mammals. These conservation patterns are maintained in human populations. Importantly, all mammalian opsins retain key amino acid residues important for conjugation to retinal-based chromophores, permitting light sensitivity. These patterns of evolution are discussed along with known functions of each atypical opsin, such as in circadian or metabolic physiology, to provide insight into the observed patterns of evolutionary constraint.
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Affiliation(s)
- Brian A. Upton
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Center for Chronobiology, Division of Pediatric Ophthalmology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Molecular & Developmental Biology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Medical Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Nicolás M. Díaz
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington
| | - Shannon A. Gordon
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington
| | - Russell N. Van Gelder
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington
- Departments of Biological Structure and Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, Washington
| | - Ethan D. Buhr
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington
| | - Richard A. Lang
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Center for Chronobiology, Division of Pediatric Ophthalmology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Department of Ophthalmology, University of Cincinnati College of Medicine, Cincinnati, Ohio
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12
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Choi EH, Daruwalla A, Suh S, Leinonen H, Palczewski K. Retinoids in the visual cycle: role of the retinal G protein-coupled receptor. J Lipid Res 2021; 62:100040. [PMID: 32493732 PMCID: PMC7910522 DOI: 10.1194/jlr.tr120000850] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/20/2020] [Indexed: 12/13/2022] Open
Abstract
Driven by the energy of a photon, the visual pigments in rod and cone photoreceptor cells isomerize 11-cis-retinal to the all-trans configuration. This photochemical reaction initiates the signal transduction pathway that eventually leads to the transmission of a visual signal to the brain and leaves the opsins insensitive to further light stimulation. For the eye to restore light sensitivity, opsins require recharging with 11-cis-retinal. This trans-cis back conversion is achieved through a series of enzymatic reactions composing the retinoid (visual) cycle. Although it is evident that the classical retinoid cycle is critical for vision, the existence of an adjunct pathway for 11-cis-retinal regeneration has been debated for many years. Retinal pigment epithelium (RPE)-retinal G protein-coupled receptor (RGR) has been identified previously as a mammalian retinaldehyde photoisomerase homologous to retinochrome found in invertebrates. Using pharmacological, genetic, and biochemical approaches, researchers have now established the physiological relevance of the RGR in 11-cis-retinal regeneration. The photoisomerase activity of RGR in the RPE and Müller glia explains how the eye can remain responsive in daylight. In this review, we will focus on retinoid metabolism in the eye and visual chromophore regeneration mediated by RGR.
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Affiliation(s)
- Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA.
| | - Anahita Daruwalla
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA; Departments of Physiology and Biophysics, and Chemistry, University of California, Irvine, CA, USA
| | - Susie Suh
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Henri Leinonen
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA; Departments of Physiology and Biophysics, and Chemistry, University of California, Irvine, CA, USA.
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13
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Non-visual Opsins and Novel Photo-Detectors in the Vertebrate Inner Retina Mediate Light Responses Within the Blue Spectrum Region. Cell Mol Neurobiol 2020; 42:59-83. [PMID: 33231827 DOI: 10.1007/s10571-020-00997-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023]
Abstract
In recent decades, a number of novel non-visual opsin photopigments belonging to the family of G protein- coupled receptors, likely involved in a number of non-image-forming processes, have been identified and characterized in cells of the inner retina of vertebrates. It is now known that the vertebrate retina is composed of visual photoreceptor cones and rods responsible for diurnal/color and nocturnal/black and white vision, and cells like the intrinsically photosensitive retinal ganglion cells (ipRGCs) and photosensitive horizontal cells in the inner retina, both detecting blue light and expressing the photopigment melanopsin (Opn4). Remarkably, these non-visual photopigments can continue to operate even in the absence of vision under retinal degeneration. Moreover, inner retinal neurons and Müller glial cells have been shown to express other photopigments such as the photoisomerase retinal G protein-coupled receptor (RGR), encephalopsin (Opn3), and neuropsin (Opn5), all able to detect blue/violet light and implicated in chromophore recycling, retinal clock synchronization, neuron-to-glia communication, and other activities. The discovery of these new photopigments in the inner retina of vertebrates is strong evidence of novel light-regulated activities. This review focuses on the features, localization, photocascade, and putative functions of these novel non-visual opsins in an attempt to shed light on their role in the inner retina of vertebrates and in the physiology of the whole organism.
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14
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von Lintig J, Moon J, Babino D. Molecular components affecting ocular carotenoid and retinoid homeostasis. Prog Retin Eye Res 2020; 80:100864. [PMID: 32339666 DOI: 10.1016/j.preteyeres.2020.100864] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/13/2020] [Accepted: 04/17/2020] [Indexed: 12/15/2022]
Abstract
The photochemistry of vision employs opsins and geometric isomerization of their covalently bound retinylidine chromophores. In different animal classes, these light receptors associate with distinct G proteins that either hyperpolarize or depolarize photoreceptor membranes. Vertebrates also use the acidic form of chromophore, retinoic acid, as the ligand of nuclear hormone receptors that orchestrate eye development. To establish and sustain these processes, animals must acquire carotenoids from the diet, transport them, and metabolize them to chromophore and retinoic acid. The understanding of carotenoid metabolism, however, lagged behind our knowledge about the biology of their receptor molecules. In the past decades, much progress has been made in identifying the genes encoding proteins that mediate the transport and enzymatic transformations of carotenoids and their retinoid metabolites. Comparative analysis in different animal classes revealed how evolutionary tinkering with a limited number of genes evolved different biochemical strategies to supply photoreceptors with chromophore. Mutations in these genes impair carotenoid metabolism and induce various ocular pathologies. This review summarizes this advancement and introduces the involved proteins, including the homeostatic regulation of their activities.
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Affiliation(s)
- Johannes von Lintig
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
| | - Jean Moon
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Darwin Babino
- Department of Ophthalmology, School of Medicine, University of Washington, Seattle, WA, USA
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15
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Ward R, Kaylor JJ, Cobice DF, Pepe DA, McGarrigle EM, Brockerhoff SE, Hurley JB, Travis GH, Kennedy BN. Non-photopic and photopic visual cycles differentially regulate immediate, early, and late phases of cone photoreceptor-mediated vision. J Biol Chem 2020; 295:6482-6497. [PMID: 32238432 DOI: 10.1074/jbc.ra119.011374] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 03/30/2020] [Indexed: 11/06/2022] Open
Abstract
Cone photoreceptors in the retina enable vision over a wide range of light intensities. However, the processes enabling cone vision in bright light (i.e. photopic vision) are not adequately understood. Chromophore regeneration of cone photopigments may require the retinal pigment epithelium (RPE) and/or retinal Müller glia. In the RPE, isomerization of all-trans-retinyl esters to 11-cis-retinol is mediated by the retinoid isomerohydrolase Rpe65. A putative alternative retinoid isomerase, dihydroceramide desaturase-1 (DES1), is expressed in RPE and Müller cells. The retinol-isomerase activities of Rpe65 and Des1 are inhibited by emixustat and fenretinide, respectively. Here, we tested the effects of these visual cycle inhibitors on immediate, early, and late phases of cone photopic vision. In zebrafish larvae raised under cyclic light conditions, fenretinide impaired late cone photopic vision, while the emixustat-treated zebrafish unexpectedly had normal vision. In contrast, emixustat-treated larvae raised under extensive dark-adaptation displayed significantly attenuated immediate photopic vision concomitant with significantly reduced 11-cis-retinaldehyde (11cRAL). Following 30 min of light, early photopic vision was recovered, despite 11cRAL levels remaining significantly reduced. Defects in immediate cone photopic vision were rescued in emixustat- or fenretinide-treated larvae following exogenous 9-cis-retinaldehyde supplementation. Genetic knockout of Des1 (degs1) or retinaldehyde-binding protein 1b (rlbp1b) did not eliminate photopic vision in zebrafish. Our findings define molecular and temporal requirements of the nonphotopic or photopic visual cycles for mediating vision in bright light.
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Affiliation(s)
- Rebecca Ward
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin D04 V1W8, Ireland
| | - Joanna J Kaylor
- Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California 90095
| | - Diego F Cobice
- Mass Spectrometry Centre, School of Biomedical Sciences, Biomedical Sciences Research Institute, Ulster University, Coleraine BT52 1SA, Northern Ireland
| | - Dionissia A Pepe
- Centre for Synthesis and Chemical Biology, UCD School of Chemistry, University College Dublin, Dublin D04 V1W8, Ireland
| | - Eoghan M McGarrigle
- Centre for Synthesis and Chemical Biology, UCD School of Chemistry, University College Dublin, Dublin D04 V1W8, Ireland
| | - Susan E Brockerhoff
- Department of Biochemistry, University of Washington, Seattle, Washington 98109.,Department of Ophthalmology, University of Washington, Seattle, Washington 98109
| | - James B Hurley
- Department of Biochemistry, University of Washington, Seattle, Washington 98109.,Department of Ophthalmology, University of Washington, Seattle, Washington 98109
| | - Gabriel H Travis
- Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California 90095.,Department of Biological Chemistry, UCLA School of Medicine, Los Angeles, California 90095
| | - Breandán N Kennedy
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin D04 V1W8, Ireland
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16
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Liu Y, Zhang W, Du X, Liu Y, Qu J, Liu X, Liu J, Zhang Q. Genome-wide identification of nonvisual opsin family reveals amplification of RPE-retinal G protein receptor gene (RGR) and offers novel insights into functions of RGR(s) in Paralichthys olivaceus (Paralichthyidae, Teleostei). JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2019; 334:25-36. [PMID: 31743605 DOI: 10.1002/jez.b.22914] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 09/08/2019] [Accepted: 10/10/2019] [Indexed: 12/20/2022]
Abstract
Opsins play important roles in the image-forming visual pathways and numerous biological systems such as the biological clock and circadian rhythm. However, the nonvisual opsins involved in nonimage forming process are not clear to date. The aim of this study was to characterize nonvisual opsins in Paralichthys olivaceus. A total of 24 nonvisual opsin genes were identified. Expressions of these genes in eye, brain, heart, testis, and fin were investigated by quantitative real-time polymerase chain reaction (qRT-PCR). Testis contained a surprisingly large number of nonvisual opsins including Opn4m2, Tmt2a, Tmt3b, Opn3, RRH, Opn7a, and Opn7b. Syntenic and phylogenetic analyses confirmed that the RGRa and RGRb originated from the teleost-specific genome duplication (TSGD). qRT-PCR results demonstrated high RGRa and RGRb expression in the eye, while the expression levels in the brain, heart, testis, and fin were relatively weak. In situ hybridization results presented here revealed the presence of both RGRa and RGRb mRNA-positive signals in the ganglion cell layer but absence in the intracellular compartment of retinal pigment epithelium (RPE) and Müller glial cells. Therefore, we hypothesized that RGRa and RGRb had undergone subfunctionalization in P. olivaceus after TSGD. In conclusion, this study provides novel insights into the evolutionary fates of the RGR genes, still, further studies need to be done to explore the mechanism about the lack of RGR genes' expression in RPE.
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Affiliation(s)
- Yuezhong Liu
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao, China
| | - Wei Zhang
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao, China
| | - Xinxin Du
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao, China
| | - Yuxiang Liu
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao, China
| | - Jiangbo Qu
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao, China
| | - Xiaobing Liu
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao, China
| | - Jinxiang Liu
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao, China.,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Quanqi Zhang
- Key Laboratory of Marine Genetics and Breeding, Ministry of Education, College of Marine Life Science, Ocean University of China, Qingdao, China.,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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17
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Zhang J, Choi EH, Tworak A, Salom D, Leinonen H, Sander CL, Hoang TV, Handa JT, Blackshaw S, Palczewska G, Kiser PD, Palczewski K. Photic generation of 11- cis-retinal in bovine retinal pigment epithelium. J Biol Chem 2019; 294:19137-19154. [PMID: 31694912 DOI: 10.1074/jbc.ra119.011169] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 10/25/2019] [Indexed: 12/19/2022] Open
Abstract
Photoisomerization of the 11-cis-retinal chromophore of rod and cone visual pigments to an all-trans-configuration is the initiating event for vision in vertebrates. The regeneration of 11-cis-retinal, necessary for sustained visual function, is an endergonic process normally conducted by specialized enzyme systems. However, 11-cis-retinal also can be formed through reverse photoisomerization from all-trans-retinal. A nonvisual opsin known as retinal pigment epithelium (RPE)-retinal G-protein-coupled receptor (RGR) was previously shown to mediate visual chromophore regeneration in photic conditions, but conflicting results have cast doubt on its role as a photoisomerase. Here, we describe high-level production of 11-cis-retinal from RPE membranes stimulated by illumination at a narrow band of wavelengths. This activity was associated with RGR and enhanced by cellular retinaldehyde-binding protein (CRALBP), which binds the 11-cis-retinal produced by RGR and prevents its re-isomerization to all-trans-retinal. The activity was recapitulated with cells heterologously expressing RGR and with purified recombinant RGR. Using an RGR variant, K255A, we confirmed that a Schiff base linkage at Lys-255 is critical for substrate binding and isomerization. Single-cell RNA-Seq analysis of the retina and RPE tissue confirmed that RGR is expressed in human and bovine RPE and Müller glia, whereas mouse RGR is expressed in RPE but not in Müller glia. These results provide key insights into the mechanisms of physiological retinoid photoisomerization and suggest a novel mechanism by which RGR, in concert with CRALBP, regenerates the visual chromophore in the RPE under sustained light conditions.
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Affiliation(s)
- Jianye Zhang
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
| | - Elliot H Choi
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697.,Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Aleksander Tworak
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
| | - David Salom
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
| | - Henri Leinonen
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
| | - Christopher L Sander
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697.,Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Thanh V Hoang
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - James T Handa
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.,Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | | | - Philip D Kiser
- Department of Physiology and Biophysics, University of California, Irvine, California 92697.,Research Service, Veterans Affairs Long Beach Healthcare System, Long Beach, California 90822
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
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18
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Rios MN, Marchese NA, Guido ME. Expression of Non-visual Opsins Opn3 and Opn5 in the Developing Inner Retinal Cells of Birds. Light-Responses in Müller Glial Cells. Front Cell Neurosci 2019; 13:376. [PMID: 31474836 PMCID: PMC6706981 DOI: 10.3389/fncel.2019.00376] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 08/02/2019] [Indexed: 11/30/2022] Open
Abstract
The avian retina is composed of different types of photoreceptors responsible for image and non-image forming tasks: the visual photoreceptor cells (cones and rods), the melanopsin-expressing intrinsically photoresponsive retinal ganglion cells (ipRGCs) and horizontal cells. Furthermore, the non-visual opsins Opn3 (encephalopsin/panaopsin) and Opn5 (neuropsin) have been shown to be expressed in the vertebrate inner retina, responding to blue (BL) and UV light, respectively. Here we investigated the expression and localization of Opn3 and Opn5 in the developing chick retina at different embryonic days (E) as well as in primary cultures of retinal Müller glial cells (MCs). Opn3 and Opn5 mRNAs and proteins appeared as early as E10 although traces of Opn3- and Opn5-like proteins were seen earlier by E7 in the forming RGC layer and in glial cells extending throughout the developing nuclear layer. Later on, at postnatal days 1–10 (PN1–10) a significant expression of Opn3 was observed in inner retinal cells and processes in plexiform layers, together with expression of the glial markers glutamine synthetase (GS) and the glial fibrillary acidic protein (GFAP). Opn3 and Opn5 were found to be expressed in primary MC cultures prepared at E8 and kept for 2 weeks. In addition, significant effects of BL exposure on Opn3 expression and subcellular localization were observed in MCs as BL significantly increased its levels and modified its nuclear location when compared with dark controls, through a mechanism dependent on protein synthesis. More importantly, a subpopulation of MCs responded to brief BL pulses by increasing intracellular Ca2+ levels; whereas light-responses were completely abolished with the retinal bleacher hydroxylamine pretreatment. Taken together, our findings show that these two opsins are expressed in inner retinal cells and MCs of the chicken retina at early developmental phases and remain expressed in the mature retina at PN days. In addition, the novel photic responses seen in MCs may suggest another important role for the glia in retinal physiology.
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Affiliation(s)
- Maximiliano N Rios
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Departamento de Química Biológica "Ranwel Caputto," Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Natalia A Marchese
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Departamento de Química Biológica "Ranwel Caputto," Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Mario E Guido
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Departamento de Química Biológica "Ranwel Caputto," Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
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19
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Morshedian A, Kaylor JJ, Ng SY, Tsan A, Frederiksen R, Xu T, Yuan L, Sampath AP, Radu RA, Fain GL, Travis GH. Light-Driven Regeneration of Cone Visual Pigments through a Mechanism Involving RGR Opsin in Müller Glial Cells. Neuron 2019; 102:1172-1183.e5. [PMID: 31056353 PMCID: PMC6586478 DOI: 10.1016/j.neuron.2019.04.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/20/2019] [Accepted: 03/29/2019] [Indexed: 11/18/2022]
Abstract
While rods in the mammalian retina regenerate rhodopsin through a well-characterized pathway in cells of the retinal pigment epithelium (RPE), cone visual pigments are thought to regenerate in part through an additional pathway in Müller cells of the neural retina. The proteins comprising this intrinsic retinal visual cycle are unknown. Here, we show that RGR opsin and retinol dehydrogenase-10 (Rdh10) convert all-trans-retinol to 11-cis-retinol during exposure to visible light. Isolated retinas from Rgr+/+ and Rgr-/- mice were exposed to continuous light, and cone photoresponses were recorded. Cones in Rgr-/- retinas lost sensitivity at a faster rate than cones in Rgr+/+ retinas. A similar effect was seen in Rgr+/+ retinas following treatment with the glial cell toxin, α-aminoadipic acid. These results show that RGR opsin is a critical component of the Müller cell visual cycle and that regeneration of cone visual pigment can be driven by light.
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Affiliation(s)
- Ala Morshedian
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Joanna J Kaylor
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Sze Yin Ng
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA; Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Avian Tsan
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Rikard Frederiksen
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Tongzhou Xu
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Lily Yuan
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Alapakkam P Sampath
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Roxana A Radu
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Gordon L Fain
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA; Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Gabriel H Travis
- Stein Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA; Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA.
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20
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Kim EW, De Leon A, Jiang Z, Radu RA, Martineau AR, Chan ED, Bai X, Su WL, Montoya DJ, Modlin RL, Liu PT. Vitamin A Metabolism by Dendritic Cells Triggers an Antimicrobial Response against Mycobacterium tuberculosis. mSphere 2019; 4:e00327-19. [PMID: 31167948 PMCID: PMC6553556 DOI: 10.1128/msphere.00327-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 05/12/2019] [Indexed: 12/24/2022] Open
Abstract
Epidemiological evidence correlates low serum vitamin A (retinol) levels with increased susceptibility to active tuberculosis (TB); however, retinol is biologically inactive and must be converted into its bioactive form, all-trans retinoic acid (ATRA). Given that ATRA triggers a Niemann-Pick type C2 (NPC2)-dependent antimicrobial response against Mycobacterium tuberculosis, we investigated the mechanism by which the immune system converts retinol into ATRA at the site of infection. We demonstrate that granulocyte-macrophage colony-stimulating factor (GM-CSF)-derived dendritic cells (DCs), but not macrophages, express enzymes in the vitamin A metabolic pathway, including aldehyde dehydrogenase 1 family, member a2 (ALDH1A2) and short-chain dehydrogenase/reductase family, member 9 (DHRS9), enzymes capable of the two-step conversion of retinol into ATRA, which is subsequently released from the cell. Additionally, mRNA and protein expression levels of ALDH1A2 and DC marker CD1B were lower in tuberculosis lung tissues than in normal lung. The conditioned medium from DCs cultured with retinol stimulated antimicrobial activity from M. tuberculosis-infected macrophages, as well as the expression of NPC2 in monocytes, which was blocked by specific inhibitors, including retinoic acid receptor inhibitor (RARi) or N,N-diethylaminobenzaldehyde (DEAB), an ALDH1A2 inhibitor. These results indicate that metabolism of vitamin A by DCs transactivates macrophage antimicrobial responses.IMPORTANCE Tuberculosis (TB) is the leading cause of death by a single infectious agent worldwide. One factor that contributes to the success of the microbe is the deficiency in immunomodulatory nutrients, such as vitamin A (retinol), which are prevalent in areas where TB is endemic. Clinical trials show that restoration of systemic retinol levels in active TB patients is ineffective in mitigating the disease; however, laboratory studies demonstrate that activation of the vitamin A pathway in Mycobacterium tuberculosis-infected macrophages triggers an antimicrobial response. Therefore, the goal of this study was to determine the link between host retinol levels and retinoic acid-mediated antimicrobial responses against M. tuberculosis By combining established in vitro models with in situ studies of lung tissue from TB patients, this study demonstrates that the innate immune system utilizes transcellular metabolism leading to activation between dendritic cells and macrophages as a means to combat the pathogen.
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Affiliation(s)
- Elliot W Kim
- Department of Molecular Biology Institute, University of California, Los Angeles, Los Angeles, California, USA
- UCLA and Orthopaedic Hospital Department of Orthopaedic Surgery, The Orthopaedic Hospital Research Center, Los Angeles, Los Angeles, California, USA
| | - Avelino De Leon
- Division of Dermatology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Zhichun Jiang
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Roxana A Radu
- Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Adrian R Martineau
- Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Edward D Chan
- Department of Medicine and Academic Affairs, National Jewish Health, Denver, Colorado, USA
| | - Xiyuan Bai
- Department of Medicine and Academic Affairs, National Jewish Health, Denver, Colorado, USA
| | - Wen-Lin Su
- Division of Pulmonary and Critical Care Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei, Taiwan
| | - Dennis J Montoya
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, California, USA
| | - Robert L Modlin
- Division of Dermatology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
- Department of Molecular Biology Institute, University of California, Los Angeles, Los Angeles, California, USA
| | - Philip T Liu
- Division of Dermatology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
- UCLA and Orthopaedic Hospital Department of Orthopaedic Surgery, The Orthopaedic Hospital Research Center, Los Angeles, Los Angeles, California, USA
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21
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Sheridan C, Boyer NP, Crouch RK, Koutalos Y. RPE65 and the Accumulation of Retinyl Esters in Mouse Retinal Pigment Epithelium. Photochem Photobiol 2018; 93:844-848. [PMID: 28500718 DOI: 10.1111/php.12738] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 12/20/2016] [Indexed: 01/12/2023]
Abstract
The RPE65 protein of the retinal pigment epithelium (RPE) enables the conversion of retinyl esters to the visual pigment chromophore 11-cis retinal. Fresh 11-cis retinal is generated from retinyl esters following photoisomerization of the visual pigment chromophore to all-trans during light detection. Large amounts of esters accumulate in Rpe65-/- mice, indicating their continuous formation when 11-cis retinal generation is blocked. We hypothesized that absence of light, by limiting the conversion of esters to 11-cis retinal, would also result in the build-up of retinyl esters in the RPE of wild-type mice. We used HPLC to quantify ester levels in organic extracts of the RPE from wild-type and Rpe65-/- mice. Retinyl ester levels in Sv/129 wild-type mice that were dark adapted for various intervals over a 4-week period were similar to those in mice raised in cyclic light. In C57BL/6 mice however, which contain less Rpe65 protein, dark adaptation was accompanied by an increase in ester levels compared to cyclic light controls. Retinyl ester levels were much higher in Rpe65-/- mice compared to wild type and kept increasing with age. The results suggest that the RPE65 role in retinyl ester homeostasis extends beyond enabling the formation of 11-cis retinal.
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Affiliation(s)
- Colleen Sheridan
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC
| | - Nicholas P Boyer
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC
| | - Rosalie K Crouch
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC
| | - Yiannis Koutalos
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC
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Structural biology of 11- cis-retinaldehyde production in the classical visual cycle. Biochem J 2018; 475:3171-3188. [PMID: 30352831 DOI: 10.1042/bcj20180193] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 09/20/2018] [Accepted: 09/26/2018] [Indexed: 12/21/2022]
Abstract
The vitamin A derivative 11-cis-retinaldehyde plays a pivotal role in vertebrate vision by serving as the chromophore of rod and cone visual pigments. In the initial step of vision, a photon is absorbed by this chromophore resulting in its isomerization to an all-trans state and consequent activation of the visual pigment and phototransduction cascade. Spent chromophore is released from the pigments through hydrolysis. Subsequent photon detection requires the delivery of regenerated 11-cis-retinaldehyde to the visual pigment. This trans-cis conversion is achieved through a process known as the visual cycle. In this review, we will discuss the enzymes, binding proteins and transporters that enable the visual pigment renewal process with a focus on advances made during the past decade in our understanding of their structural biology.
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Gu L, Bok D, Yu F, Caprioli J, Piri N. Downregulation of splicing regulator RBFOX1 compromises visual depth perception. PLoS One 2018; 13:e0200417. [PMID: 30001398 PMCID: PMC6042722 DOI: 10.1371/journal.pone.0200417] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 06/26/2018] [Indexed: 02/05/2023] Open
Abstract
Rbfox1 is a splicing regulator that has been associated with various neurological conditions such as autism spectrum disorder, mental retardation, epilepsy, attention-deficit/hyperactivity disorder and schizophrenia. We show that in adult rodent retinas, Rbfox1 is expressed in all types of retinal ganglion cells (RGCs) and in certain subsets of amacrine cells (ACs), within the inner nuclear (INL) and ganglion cell (GCL) layers. In the INL, all Rbfox1-positive cells were colocalized with GABAergic ACs, however not all GABAergic ACs were immunostained for Rbfox1. In the GCL, a vast majority of GABAergic dACs were Rbfox1-immunopositive. Furthermore, all cholinergic starburst ACs (SACs) in the INL (type a) and in the GCL (type b) were Rbfox1 positive. The expression of Rbfox1 in the retina significantly overlapped with expression of Rbfox2, another member of Rbfox family of proteins. Rbfox2, in addition to RGCs and ACs, was also expressed in horizontal cells. In developing retinas at E12 and E15, Rbfox1 is localized to the cytoplasm of differentiating RGCs and ACs. Between P0 and P5, Rbfox1 subcellular localization switched from cytoplasmic to predominantly nuclear. Downregulation of Rbfox1 in adult Rbfox1loxP/loxP mice had no detectable effect on retinal gross morphology. However, the visual cliff test revealed marked abnormalities of depth perception of these animals. RNA sequencing of retinal transcriptomes of control and Rbfox1 knockout animals identified a number of Rbfox1-regulated genes that are involved in establishing neuronal circuits and synaptic transmission, including Vamp1, Vamp2, Snap25, Trak2, and Slc1A7, suggesting the role of Rbfox1 in facilitating synaptic communications between ACs and RGCs.
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Affiliation(s)
- Lei Gu
- Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, United States of America
| | - Dean Bok
- Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, United States of America
- Department of Neurobiology, University of California, Los Angeles, Los Angeles, CA, United States of America
| | - Fei Yu
- Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, United States of America
| | - Joseph Caprioli
- Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, United States of America
| | - Natik Piri
- Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, United States of America
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24
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Zhang Z, Fong HK. Coexpression of nonvisual opsin, retinal G protein-coupled receptor, and visual pigments in human and bovine cone photoreceptors. Mol Vis 2018; 24:434-442. [PMID: 30034210 PMCID: PMC6031102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 06/29/2018] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Retinal G protein-coupled receptor (RGR) mRNA is transcribed in the outer nuclear layer of human retinas; however, it is not known whether the RGR gene is expressed in the rod or cone photoreceptors. In this study, we investigate broader expression of the normal RGR isoform in photoreceptors of human and bovine retinas. METHODS We produced and validated a rabbit polyclonal antipeptide antibody (DE15) that is directed against a peptide sequence (SSLLRRWPHGSEGC) partly conserved in RGR across several species. Bovine and human retina sections were analyzed with immunohistochemical and double-label immunofluorescent staining. RESULTS The DE15 antibody bound specifically to overexpressed recombinant RGR, purified RGR from bovine RPE, and RGR in crude RPE membrane extracts without cross-reaction to other proteins. Immunostaining of diurnal bovine and human retinas with DE15 showed labeling of long-wavelength-sensitive and short-wavelength-sensitive cone photoreceptors and some retinal ganglion cells in both species. Strong labeling with DE15 was detected throughout the cone photoreceptor, including the outer segment, inner segment, cell body, axon, and cone pedicle, while rod outer segments were negative. Immunostaining for human exon-6-skipping RGR (RGR-d) was found primarily at the tips of the outer segment of the cones. CONCLUSIONS The results indicate that the cone photoreceptors in these mammals express a nonvisual opsin of the Go/RGR or tetraopsin group. RGR and the visual pigments are predominantly colocalized in the cone outer segment, which suggests functional interaction among these opsins. Human cone photoreceptors may also contain normal RGR and the aberrant RGR-d splice isoform.
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Affiliation(s)
- Zhaoxia Zhang
- Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA,USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA
| | - Henry K.W. Fong
- Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA,Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California, Los Angeles, CA,USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA
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25
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Tedja MS, Wojciechowski R, Hysi PG, Eriksson N, Furlotte NA, Verhoeven VJ, Iglesias AI, Meester-Smoor MA, Tompson SW, Fan Q, Khawaja AP, Cheng CY, Höhn R, Yamashiro K, Wenocur A, Grazal C, Haller T, Metspalu A, Wedenoja J, Jonas JB, Wang YX, Xie J, Mitchell P, Foster PJ, Klein BE, Klein R, Paterson AD, Hosseini SM, Shah RL, Williams C, Teo YY, Tham YC, Gupta P, Zhao W, Shi Y, Saw WY, Tai ES, Sim XL, Huffman JE, Polašek O, Hayward C, Bencic G, Rudan I, Wilson JF, Joshi PK, Tsujikawa A, Matsuda F, Whisenhunt KN, Zeller T, van der Spek PJ, Haak R, Meijers-Heijboer H, van Leeuwen EM, Iyengar SK, Lass JH, Hofman A, Rivadeneira F, Uitterlinden AG, Vingerling JR, Lehtimäki T, Raitakari OT, Biino G, Concas MP, Schwantes-An TH, Igo RP, Cuellar-Partida G, Martin NG, Craig JE, Gharahkhani P, Williams KM, Nag A, Rahi JS, Cumberland PM, Delcourt C, Bellenguez C, Ried JS, Bergen AA, Meitinger T, Gieger C, Wong TY, Hewitt AW, Mackey DA, Simpson CL, Pfeiffer N, Pärssinen O, Baird PN, Vitart V, Amin N, van Duijn CM, Bailey-Wilson JE, Young TL, Saw SM, Stambolian D, MacGregor S, Guggenheim JA, Tung JY, Hammond CJ, Klaver CC. Genome-wide association meta-analysis highlights light-induced signaling as a driver for refractive error. Nat Genet 2018; 50:834-848. [PMID: 29808027 PMCID: PMC5980758 DOI: 10.1038/s41588-018-0127-7] [Citation(s) in RCA: 193] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 03/26/2018] [Indexed: 12/18/2022]
Abstract
Refractive errors, including myopia, are the most frequent eye disorders worldwide and an increasingly common cause of blindness. This genome-wide association meta-analysis in 160,420 participants and replication in 95,505 participants increased the number of established independent signals from 37 to 161 and showed high genetic correlation between Europeans and Asians (>0.78). Expression experiments and comprehensive in silico analyses identified retinal cell physiology and light processing as prominent mechanisms, and also identified functional contributions to refractive-error development in all cell types of the neurosensory retina, retinal pigment epithelium, vascular endothelium and extracellular matrix. Newly identified genes implicate novel mechanisms such as rod-and-cone bipolar synaptic neurotransmission, anterior-segment morphology and angiogenesis. Thirty-one loci resided in or near regions transcribing small RNAs, thus suggesting a role for post-transcriptional regulation. Our results support the notion that refractive errors are caused by a light-dependent retina-to-sclera signaling cascade and delineate potential pathobiological molecular drivers.
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Affiliation(s)
- Milly S. Tedja
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Robert Wojciechowski
- Department of Epidemiology and Medicine, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
- Wilmer Eye Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Pirro G. Hysi
- Section of Academic Ophthalmology, School of Life Course Sciences, King’s College London, London, UK
| | | | | | - Virginie J.M. Verhoeven
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Adriana I. Iglesias
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Magda A. Meester-Smoor
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Stuart W. Tompson
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Qiao Fan
- Centre for Quantitative Medicine, DUKE-National University of Singapore, Singapore
| | - Anthony P. Khawaja
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Ching-Yu Cheng
- Centre for Quantitative Medicine, DUKE-National University of Singapore, Singapore
- Ocular Epidemiology Research Group, Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - René Höhn
- Department of Ophthalmology, University Hospital Bern, Inselspital, University of Bern, Bern, Switzerland
- Department of Ophthalmology, University Medical Center Mainz, Mainz, Germany
| | - Kenji Yamashiro
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Adam Wenocur
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Clare Grazal
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Toomas Haller
- Estonian Genome Center, University of Tartu, Tartu, Estonia
| | | | - Juho Wedenoja
- Department of Ophthalmology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Department of Public Health, University of Helsinki, Helsinki, Finland
| | - Jost B. Jonas
- Department of Ophthalmology, Medical Faculty Mannheim of the Ruprecht-Karls-University of Heidelberg, Mannheim, Germany
- Beijing Institute of Ophthalmology, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Ya Xing Wang
- Beijing Institute of Ophthalmology, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Jing Xie
- Centre for Eye Research Australia, Ophthalmology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Paul Mitchell
- Department of Ophthalmology, Centre for Vision Research, Westmead Institute for Medical Research, University of Sydney, Sydney, Australia
| | - Paul J. Foster
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Barbara E.K. Klein
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Ronald Klein
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Andrew D. Paterson
- Program in Genetics and Genome Biology, Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
| | - S. Mohsen Hosseini
- Program in Genetics and Genome Biology, Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
| | - Rupal L. Shah
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, UK
| | - Cathy Williams
- Department of Population Health Sciences, Bristol Medical School, Bristol, UK
| | - Yik Ying Teo
- Department of Statistics and Applied Probability, National University of Singapore, Singapore
- Saw Swee Hock School of Public Health, National University Health Systems, National University of Singapore, Singapore
| | - Yih Chung Tham
- Ocular Epidemiology Research Group, Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Preeti Gupta
- Department of Health Service Research, Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Wanting Zhao
- Centre for Quantitative Medicine, DUKE-National University of Singapore, Singapore
- Statistics Support Platform, Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Yuan Shi
- Statistics Support Platform, Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Woei-Yuh Saw
- Life Sciences Institute, National University of Singapore, Singapore
| | - E-Shyong Tai
- Saw Swee Hock School of Public Health, National University Health Systems, National University of Singapore, Singapore
| | - Xue Ling Sim
- Saw Swee Hock School of Public Health, National University Health Systems, National University of Singapore, Singapore
| | - Jennifer E. Huffman
- MRC Human Genetics Unit, MRC Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Ozren Polašek
- Faculty of Medicine, University of Split, Split, Croatia
| | - Caroline Hayward
- MRC Human Genetics Unit, MRC Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Goran Bencic
- Department of Ophthalmology, Sisters of Mercy University Hospital, Zagreb, Croatia
| | - Igor Rudan
- Centre for Global Health Research, Usher Institute for Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UK
| | - James F. Wilson
- MRC Human Genetics Unit, MRC Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, UK
- Centre for Global Health Research, Usher Institute for Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UK
| | | | | | | | - Peter K. Joshi
- Centre for Global Health Research, Usher Institute for Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UK
| | - Akitaka Tsujikawa
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Fumihiko Matsuda
- Center for Genomic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Kristina N. Whisenhunt
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Tanja Zeller
- Clinic for General and Interventional Cardiology, University Heart Center Hamburg, Hamburg, Germany
| | | | - Roxanna Haak
- Department of Bioinformatics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Hanne Meijers-Heijboer
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands
| | - Elisabeth M. van Leeuwen
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Sudha K. Iyengar
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University and University Hospitals Eye Institute, Cleveland, Ohio, USA
- Department of Genetics, Case Western Reserve University, Cleveland, Ohio, USA
| | - Jonathan H. Lass
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University and University Hospitals Eye Institute, Cleveland, Ohio, USA
| | - Albert Hofman
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Harvard T.HChan School of Public Health, Boston, Massachusetts, USA
- Netherlands Consortium for Healthy Ageing, Netherlands Genomics Initiative, the Hague, the Netherlands
| | - Fernando Rivadeneira
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Netherlands Consortium for Healthy Ageing, Netherlands Genomics Initiative, the Hague, the Netherlands
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - André G. Uitterlinden
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Netherlands Consortium for Healthy Ageing, Netherlands Genomics Initiative, the Hague, the Netherlands
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Terho Lehtimäki
- Department of Clinical Chemistry, Finnish Cardiovascular Research Center-Tampere, Faculty of Medicine and Life Sciences, University of Tampere
- Department of Clinical Chemistry, Fimlab Laboratories, University of Tampere, Tampere, Finland
| | - Olli T. Raitakari
- Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland
- Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital, Turku, Finland
| | - Ginevra Biino
- Institute of Molecular Genetics, National Research Council of Italy, Sassari, Italy
| | - Maria Pina Concas
- Institute for Maternal and Child Health - IRCCS “Burlo Garofolo”, Trieste, Italy
| | - Tae-Hwi Schwantes-An
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
- Department of Medical and Molecular Genetics, Indiana University, School of Medicine, Indianapolis, Indiana, USA
| | - Robert P. Igo
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, Ohio, USA
| | | | - Nicholas G. Martin
- Genetic Epidemiology, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jamie E. Craig
- Department of Ophthalmology, Flinders University, Adelaide, Australia
| | - Puya Gharahkhani
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Katie M. Williams
- Section of Academic Ophthalmology, School of Life Course Sciences, King’s College London, London, UK
| | - Abhishek Nag
- Department of Twin Research and Genetic Epidemiology, King’s College London, London, UK
| | - Jugnoo S. Rahi
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
- Great Ormond Street Institute of Child Health, University College London, London, UK
- Ulverscroft Vision Research Group, University College London, London, UK
| | | | - Cécile Delcourt
- Université de Bordeaux, Inserm, Bordeaux Population Health Research Center, team LEHA, UMR 1219, F-33000 Bordeaux, France
| | - Céline Bellenguez
- Institut Pasteur de Lille, Lille, France
- Inserm, U1167, RID-AGE - Risk factors and molecular determinants of aging-related diseases, Lille, France
- Université de Lille, U1167 - Excellence Laboratory LabEx DISTALZ, Lille, France
| | - Janina S. Ried
- Institute of Genetic Epidemiology, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg, Germany
| | - Arthur A. Bergen
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands
- Department of Ophthalmology, Academic Medical Center, Amsterdam, The Netherlands
- The Netherlands Institute for Neurosciences (NIN-KNAW), Amsterdam, The Netherlands
| | - Thomas Meitinger
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Human Genetics, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Christian Gieger
- Institute of Genetic Epidemiology, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg, Germany
| | - Tien Yin Wong
- Academic Medicine Research Institute, Singapore
- Retino Center, Singapore National Eye Centre, Singapore, Singapore
| | - Alex W. Hewitt
- Centre for Eye Research Australia, Ophthalmology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Department of Ophthalmology, Menzies Institute of Medical Research, University of Tasmania, Hobart, Australia
- Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, Australia
| | - David A. Mackey
- Centre for Eye Research Australia, Ophthalmology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Department of Ophthalmology, Menzies Institute of Medical Research, University of Tasmania, Hobart, Australia
- Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, Australia
| | - Claire L. Simpson
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Sciences Center, Memphis, Tenessee
| | - Norbert Pfeiffer
- Department of Ophthalmology, University Medical Center Mainz, Mainz, Germany
| | - Olavi Pärssinen
- Department of Ophthalmology, Central Hospital of Central Finland, Jyväskylä, Finland
- Gerontology Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Paul N. Baird
- Centre for Eye Research Australia, Ophthalmology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Veronique Vitart
- MRC Human Genetics Unit, MRC Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Najaf Amin
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Joan E. Bailey-Wilson
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Terri L. Young
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Seang-Mei Saw
- Saw Swee Hock School of Public Health, National University Health Systems, National University of Singapore, Singapore
- Myopia Research Group, Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Dwight Stambolian
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stuart MacGregor
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | | | | | - Christopher J. Hammond
- Section of Academic Ophthalmology, School of Life Course Sciences, King’s College London, London, UK
| | - Caroline C.W. Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
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26
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An all-trans-retinal-binding opsin peropsin as a potential dark-active and light-inactivated G protein-coupled receptor. Sci Rep 2018; 8:3535. [PMID: 29476064 PMCID: PMC5824942 DOI: 10.1038/s41598-018-21946-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 02/13/2018] [Indexed: 12/15/2022] Open
Abstract
Peropsin or retinal pigment epithelium-derived rhodopsin homolog, found in many animals, belongs to the opsin family. Most opsins bind to 11-cis-retinal as a chromophore and act as light-activated G protein-coupled receptors. Some peropsins, however, bind all-trans-retinal and isomerise it into 11-cis form by light, and peropsin has been suggested to supply other visual opsins with 11-cis-retinal. Additionally, peropsin has some amino acid sequence motifs that are highly conserved among G protein-coupled opsins. Here, using chimeric mutant peropsins, we found that peropsin potentially generates an “active form” that drives G-protein signalling in the dark by binding to all-trans-retinal and that the active form photo-converts to an inactive form containing 11-cis-retinal. Comparative spectroscopic analysis demonstrated that spider peropsin exhibited catalytic efficiency for retinal photoisomerisation that was much lower than a retinal photoisomerase, squid retinochrome. The chimeric peropsins, constructed by replacing the third intracellular loop region with that of Gs- or Gi-coupled opsin, were active and drove Gs- or Gi-mediated signalling in the dark, respectively, and were inactivated upon illumination in mammalian cultured cells. These results suggest that peropsin acts as a dark-active, light-inactivated G protein-coupled receptor and is useful as a novel optogenetic tool.
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27
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Ramirez MD, Pairett AN, Pankey MS, Serb JM, Speiser DI, Swafford AJ, Oakley TH. The Last Common Ancestor of Most Bilaterian Animals Possessed at Least Nine Opsins. Genome Biol Evol 2018; 8:3640-3652. [PMID: 28172965 PMCID: PMC5521729 DOI: 10.1093/gbe/evw248] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2016] [Indexed: 12/17/2022] Open
Abstract
The opsin gene family encodes key proteins animals use to sense light and has expanded dramatically as it originated early in animal evolution. Understanding the origins of opsin diversity can offer clues to how separate lineages of animals have repurposed different opsin paralogs for different light-detecting functions. However, the more we look for opsins outside of eyes and from additional animal phyla, the more opsins we uncover, suggesting we still do not know the true extent of opsin diversity, nor the ancestry of opsin diversity in animals. To estimate the number of opsin paralogs present in both the last common ancestor of the Nephrozoa (bilaterians excluding Xenoacoelomorpha), and the ancestor of Cnidaria + Bilateria, we reconstructed a reconciled opsin phylogeny using sequences from 14 animal phyla, especially the traditionally poorly-sampled echinoderms and molluscs. Our analysis strongly supports a repertoire of at least nine opsin paralogs in the bilaterian ancestor and at least four opsin paralogs in the last common ancestor of Cnidaria + Bilateria. Thus, the kernels of extant opsin diversity arose much earlier in animal history than previously known. Further, opsins likely duplicated and were lost many times, with different lineages of animals maintaining different repertoires of opsin paralogs. This phylogenetic information can inform hypotheses about the functions of different opsin paralogs and can be used to understand how and when opsins were incorporated into complex traits like eyes and extraocular sensors.
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Affiliation(s)
- M Desmond Ramirez
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA
| | - Autum N Pairett
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA
| | - M Sabrina Pankey
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH
| | - Jeanne M Serb
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA
| | - Daniel I Speiser
- Department of Biological Sciences, University of South Carolina, Columbia, SC
| | - Andrew J Swafford
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA
| | - Todd H Oakley
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA
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28
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Cook JD, Ng SY, Lloyd M, Eddington S, Sun H, Nathans J, Bok D, Radu RA, Travis GH. Peropsin modulates transit of vitamin A from retina to retinal pigment epithelium. J Biol Chem 2017; 292:21407-21416. [PMID: 29109151 DOI: 10.1074/jbc.m117.812701] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 10/31/2017] [Indexed: 11/06/2022] Open
Abstract
Peropsin is a non-visual opsin in both vertebrate and invertebrate species. In mammals, peropsin is present in the apical microvilli of retinal pigment epithelial (RPE) cells. These structures interdigitate with the outer segments of rod and cone photoreceptor cells. RPE cells play critical roles in the maintenance of photoreceptors, including the recycling of visual chromophore for the opsin visual pigments. Here, we sought to identify the function of peropsin in the mouse eye. To this end, we generated mice with a null mutation in the peropsin gene (Rrh). These mice exhibited normal retinal histology, normal morphology of outer segments and RPE cells, and no evidence of photoreceptor degeneration. Biochemically, Rrh-/- mice had ∼2-fold higher vitamin A (all-trans-retinol (all-trans-ROL)) in the neural retina following a photobleach and 5-fold lower retinyl esters in the RPE. This phenotype was similar to those reported in mice that lack interphotoreceptor retinoid-binding protein (IRBP) or cellular retinol-binding protein, suggesting that peropsin plays a role in the movement of all-trans-ROL from photoreceptors to the RPE. We compared the phenotypes in mice lacking both peropsin and IRBP with those of mice lacking peropsin or IRBP alone and found that the retinoid phenotype was similarly severe in each of these knock-out mice. We conclude that peropsin controls all-trans-ROL movement from the retina to the RPE or may regulate all-trans-ROL storage within the RPE. We propose that peropsin affects light-dependent regulation of all-trans-ROL uptake from photoreceptors into RPE cells through an as yet undefined mechanism.
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Affiliation(s)
- Jeremy D Cook
- From the Department of Ophthalmology, Stein Eye Institute
| | - Sze Yin Ng
- From the Department of Ophthalmology, Stein Eye Institute
| | - Marcia Lloyd
- From the Department of Ophthalmology, Stein Eye Institute
| | | | - Hui Sun
- From the Department of Ophthalmology, Stein Eye Institute.,Department of Physiology, and
| | - Jeremy Nathans
- Department of Molecular Biology and Genetics, Neuroscience, and Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, and.,Howard Hughes Medical Institute, Baltimore, Maryland 21205
| | - Dean Bok
- From the Department of Ophthalmology, Stein Eye Institute
| | - Roxana A Radu
- From the Department of Ophthalmology, Stein Eye Institute
| | - Gabriel H Travis
- From the Department of Ophthalmology, Stein Eye Institute, .,Department of Biological Chemistry, School of Medicine, UCLA, Los Angeles, California 90095
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29
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Abstract
Rhodopsin is the classical light sensor. Although rhodopsin has long been known to be important for image formation in the eye, the requirements for opsins in non-image formation and in extraocular light sensation were revealed much later. Most recent is the demonstration that an opsin in the fruit fly, Drosophila melanogaster, is expressed in pacemaker neurons in the brain and functions in light entrainment of circadian rhythms. However, the biggest surprise is that opsins have light-independent roles, countering more than a century of dogma that they function exclusively as light sensors. Through studies in Drosophila, light-independent roles of opsins have emerged in temperature sensation and hearing. Although these findings have been uncovered in the fruit fly, there are hints that opsins have light-independent roles in a wide array of animals, including mammals. Thus, despite the decades of focus on opsins as light detectors, they represent an important new class of polymodal sensory receptor.
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Affiliation(s)
- Nicole Y Leung
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106;
| | - Craig Montell
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106;
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30
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Kaylor JJ, Xu T, Ingram NT, Tsan A, Hakobyan H, Fain GL, Travis GH. Blue light regenerates functional visual pigments in mammals through a retinyl-phospholipid intermediate. Nat Commun 2017; 8:16. [PMID: 28473692 PMCID: PMC5432035 DOI: 10.1038/s41467-017-00018-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 02/15/2017] [Indexed: 11/24/2022] Open
Abstract
The light absorbing chromophore in opsin visual pigments is the protonated Schiff base of 11-cis-retinaldehyde (11cRAL). Absorption of a photon isomerizes 11cRAL to all-trans-retinaldehyde (atRAL), briefly activating the pigment before it dissociates. Light sensitivity is restored when apo-opsin combines with another 11cRAL to form a new visual pigment. Conversion of atRAL to 11cRAL is carried out by enzyme pathways in neighboring cells. Here we show that blue (450-nm) light converts atRAL specifically to 11cRAL through a retinyl-phospholipid intermediate in photoreceptor membranes. The quantum efficiency of this photoconversion is similar to rhodopsin. Photoreceptor membranes synthesize 11cRAL chromophore faster under blue light than in darkness. Live mice regenerate rhodopsin more rapidly in blue light. Finally, whole retinas and isolated cone cells show increased photosensitivity following exposure to blue light. These results indicate that light contributes to visual-pigment renewal in mammalian rods and cones through a non-enzymatic process involving retinyl-phospholipids. It is currently thought that visual pigments in vertebrate photoreceptors are regenerated exclusively through enzymatic cycles. Here the authors show that mammalian photoreceptors also regenerate opsin pigments in light through photoisomerization of N-ret-PE (N-retinylidene-phosphatidylethanolamine.
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Affiliation(s)
- Joanna J Kaylor
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Tongzhou Xu
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA.,Molecular, Cellular and Integrative Physiology Graduate Program, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Norianne T Ingram
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA.,Molecular, Cellular and Integrative Physiology Graduate Program, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Avian Tsan
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Hayk Hakobyan
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Gordon L Fain
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA.,Department of Integrative Biology and Physiology, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Gabriel H Travis
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA. .,Department of Biological Chemistry, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA.
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31
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Complement modulation in the retinal pigment epithelium rescues photoreceptor degeneration in a mouse model of Stargardt disease. Proc Natl Acad Sci U S A 2017; 114:3987-3992. [PMID: 28348233 DOI: 10.1073/pnas.1620299114] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Recessive Stargardt macular degeneration (STGD1) is caused by mutations in the gene for the ABCA4 transporter in photoreceptor outer segments. STGD1 patients and Abca4-/- (STGD1) mice exhibit buildup of bisretinoid-containing lipofuscin pigments in the retinal pigment epithelium (RPE), increased oxidative stress, augmented complement activation and slow degeneration of photoreceptors. A reduction in complement negative regulatory proteins (CRPs), possibly owing to bisretinoid accumulation, may be responsible for the increased complement activation seen on the RPE of STGD1 mice. CRPs prevent attack on host cells by the complement system, and complement receptor 1-like protein y (CRRY) is an important CRP in mice. Here we attempted to rescue the phenotype in STGD1 mice by increasing expression of CRRY in the RPE using a gene therapy approach. We injected recombinant adeno-associated virus containing the CRRY coding sequence (AAV-CRRY) into the subretinal space of 4-wk-old Abca4-/- mice. This resulted in sustained, several-fold increased expression of CRRY in the RPE, which significantly reduced the complement factors C3/C3b in the RPE. Unexpectedly, AAV-CRRY-treated STGD1 mice also showed reduced accumulation of bisretinoids compared with sham-injected STGD1 control mice. Furthermore, we observed slower photoreceptor degeneration and increased visual chromophore in 1-y-old AAV-CRRY-treated STGD1 mice. Rescue of the STGD1 phenotype by AAV-CRRY gene therapy suggests that complement attack on the RPE is an important etiologic factor in STGD1. Modulation of the complement system by locally increasing CRP expression using targeted gene therapy represents a potential treatment strategy for STGD1 and other retinopathies associated with complement dysregulation.
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Tyrosinase-Cre-Mediated Deletion of the Autophagy Gene Atg7 Leads to Accumulation of the RPE65 Variant M450 in the Retinal Pigment Epithelium of C57BL/6 Mice. PLoS One 2016; 11:e0161640. [PMID: 27537685 PMCID: PMC4990303 DOI: 10.1371/journal.pone.0161640] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 08/09/2016] [Indexed: 12/26/2022] Open
Abstract
Targeted gene knockout mouse models have helped to identify roles of autophagy in many tissues. Here, we investigated the retinal pigment epithelium (RPE) of Atg7f/f Tyr-Cre mice (on a C57BL/6 background), in which Cre recombinase is expressed under the control of the tyrosinase promoter to delete the autophagy gene Atg7. In line with pigment cell-directed blockade of autophagy, the RPE and the melanocytes of the choroid showed strong accumulation of the autophagy adaptor and substrate, sequestosome 1 (Sqstm1)/p62, relative to the levels in control mice. Immunofluorescence and Western blot analysis demonstrated that the RPE, but not the choroid melanocytes, of Atg7f/f Tyr-Cre mice also had strongly increased levels of retinoid isomerohydrolase RPE65, a pivotal enzyme for the maintenance of visual perception. In contrast to Sqstm1, genes involved in retinal regeneration, i.e. Lrat, Rdh5, Rgr, and Rpe65, were expressed at higher mRNA levels. Sequencing of the Rpe65 gene showed that Atg7f/f and Atg7f/f Tyr-Cre mice carry a point mutation (L450M) that is characteristic for the C57BL/6 mouse strain and reportedly causes enhanced degradation of the RPE65 protein by an as-yet unknown mechanism. These results suggest that the increased abundance of RPE65 M450 in the RPE of Atg7f/f Tyr-Cre mice is, at least partly, mediated by upregulation of Rpe65 transcription; however, our data are also compatible with the hypothesis that the RPE65 M450 protein is degraded by Atg7-dependent autophagy in Atg7f/f mice. Further studies in mice of different genetic backgrounds are necessary to determine the relative contributions of these mechanisms.
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33
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Abstract
Recent progress in molecular understanding of the retinoid cycle in mammalian retina stems from painstaking biochemical reconstitution studies supported by natural or engineered animal models with known genetic lesions and studies of humans with specific genetic blinding diseases. Structural and membrane biology have been used to detect critical retinal enzymes and proteins and their substrates and ligands, placing them in a cellular context. These studies have been supplemented by analytical chemistry methods that have identified small molecules by their spectral characteristics, often in conjunction with the evaluation of models of animal retinal disease. It is from this background that rational therapeutic interventions to correct genetic defects or environmental insults are identified. Thus, most presently accepted modulators of the retinoid cycle already have demonstrated promising results in animal models of retinal degeneration. These encouraging signs indicate that some human blinding diseases can be alleviated by pharmacological interventions.
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Affiliation(s)
- Philip D Kiser
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106 ; Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio 44106
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
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34
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The Visual Cycle in the Inner Retina of Chicken and the Involvement of Retinal G-Protein-Coupled Receptor (RGR). Mol Neurobiol 2016; 54:2507-2517. [DOI: 10.1007/s12035-016-9830-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/04/2016] [Indexed: 11/27/2022]
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35
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Kochounian H, Zhang Z, Spee C, Hinton DR, Fong HKW. Targeting of exon VI-skipping human RGR-opsin to the plasma membrane of pigment epithelium and co-localization with terminal complement complex C5b-9. Mol Vis 2016; 22:213-23. [PMID: 27011730 PMCID: PMC4783578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 03/01/2016] [Indexed: 10/26/2022] Open
Abstract
PURPOSE Rare mutations in the human RGR gene lead to autosomal recessive retinitis pigmentosa or dominantly inherited peripapillary choroidal atrophy. Here, we analyze a common exon-skipping isoform of the human retinal G protein-coupled receptor opsin (RGR-d) to determine differences in subcellular targeting between RGR-d and normal RGR and possible association with abnormal traits in the human eye. METHODS The terminal complement complex (C5b-9), vitronectin, CD46, syntaxin-4, and RGR-d were analyzed in human eye tissue from young and old donors or in cultured fetal RPE cells by means of immunofluorescent labeling and high-resolution confocal microscopy or immunohistochemical staining. RESULTS We observed that RGR-d is targeted to the basolateral plasma membrane of the RPE. RGR-d, but not normal RGR, is expressed in cultured human fetal RPE cells in which the protein also trafficks to the plasma membrane. In young donors, the amount of RGR-d protein in the basolateral plasma membrane was much higher than that in the RPE cells of older subjects. In older donor eyes, the level of immunoreactive RGR-d within RPE cells was often low or undetectable, and immunostaining of RGR-d was consistently strongest in extracellular deposits in Bruch's membrane. Double immunofluorescent labeling in the basal deposits revealed significant aggregate and small punctate co-localization of RGR-d with C5b-9 and vitronectin. CONCLUSIONS RGR-d may escape endoplasmic reticulum-associated degradation and in contrast to full-length RGR, traffick to the basolateral plasma membrane, particularly in younger subjects. RGR-d in the plasma membrane indicates that the protein is properly folded, as misfolded membrane proteins cannot otherwise sort to the plasma membrane. The close association of extracellular RGR-d with both vitronectin and C5b-9 suggests a potential role of RGR-d-containing deposits in complement activation.
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Affiliation(s)
| | - Zhaoxia Zhang
- Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA
- USC Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA
| | - Christine Spee
- Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA
| | - David R. Hinton
- Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA
- Department of Pathology, Keck School of Medicine of the University of Southern California, Los Angeles, CA
- USC Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA
| | - Henry K. W. Fong
- Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA
- Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California, Los Angeles, CA
- USC Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA
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36
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Abstract
Visual systems detect light by monitoring the effect of photoisomerization of a chromophore on the release of a neurotransmitter from sensory neurons, known as rod and cone photoreceptor cells in vertebrate retina. In all known visual systems, the chromophore is 11-cis-retinal complexed with a protein, called opsin, and photoisomerization produces all-trans-retinal. In mammals, regeneration of 11-cis-retinal following photoisomerization occurs by a thermally driven isomerization reaction. Additional reactions are required during regeneration to protect cells from the toxicity of aldehyde forms of vitamin A that are essential to the visual process. Photochemical and phototransduction reactions in rods and cones are identical; however, reactions of the rod and cone visual pigment regeneration cycles differ, and perplexingly, rod and cone regeneration cycles appear to use different mechanisms to overcome the energy barrier involved in converting all-trans- to 11-cis-retinoid. Abnormal processing of all-trans-retinal in the rod regeneration cycle leads to retinal degeneration, suggesting that excessive amounts of the retinoid itself or its derivatives are toxic. This line of reasoning led to the development of various approaches to modifying the activity of the rod visual cycle as a possible therapeutic approach to delay or prevent retinal degeneration in inherited retinal diseases and perhaps in the dry form of macular degeneration (geographic atrophy). In spite of great progress in understanding the functioning of rod and cone regeneration cycles at a molecular level, resolution of a number of remaining puzzling issues will offer insight into the amelioration of several blinding retinal diseases.
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37
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Díaz NM, Morera LP, Guido ME. Melanopsin and the Non-visual Photochemistry in the Inner Retina of Vertebrates. Photochem Photobiol 2015; 92:29-44. [DOI: 10.1111/php.12545] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 10/09/2015] [Indexed: 01/28/2023]
Affiliation(s)
- Nicolás M. Díaz
- Departamento de Química Biológica-CIQUIBIC (CONICET); Facultad de Ciencias Químicas; Universidad Nacional de Córdoba (UNC); Córdoba Argentina
| | - Luis P. Morera
- Departamento de Química Biológica-CIQUIBIC (CONICET); Facultad de Ciencias Químicas; Universidad Nacional de Córdoba (UNC); Córdoba Argentina
| | - Mario E. Guido
- Departamento de Química Biológica-CIQUIBIC (CONICET); Facultad de Ciencias Químicas; Universidad Nacional de Córdoba (UNC); Córdoba Argentina
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38
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Neuropsin (OPN5)-mediated photoentrainment of local circadian oscillators in mammalian retina and cornea. Proc Natl Acad Sci U S A 2015; 112:13093-8. [PMID: 26392540 DOI: 10.1073/pnas.1516259112] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The molecular circadian clocks in the mammalian retina are locally synchronized by environmental light cycles independent of the suprachiasmatic nuclei (SCN) in the brain. Unexpectedly, this entrainment does not require rods, cones, or melanopsin (OPN4), possibly suggesting the involvement of another retinal photopigment. Here, we show that the ex vivo mouse retinal rhythm is most sensitive to short-wavelength light but that this photoentrainment requires neither the short-wavelength-sensitive cone pigment [S-pigment or cone opsin (OPN1SW)] nor encephalopsin (OPN3). However, retinas lacking neuropsin (OPN5) fail to photoentrain, even though other visual functions appear largely normal. Initial evidence suggests that OPN5 is expressed in select retinal ganglion cells. Remarkably, the mouse corneal circadian rhythm is also photoentrainable ex vivo, and this photoentrainment likewise requires OPN5. Our findings reveal a light-sensing function for mammalian OPN5, until now an orphan opsin.
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39
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Ernst OP, Lodowski DT, Elstner M, Hegemann P, Brown L, Kandori H. Microbial and animal rhodopsins: structures, functions, and molecular mechanisms. Chem Rev 2014; 114:126-63. [PMID: 24364740 PMCID: PMC3979449 DOI: 10.1021/cr4003769] [Citation(s) in RCA: 746] [Impact Index Per Article: 74.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Indexed: 12/31/2022]
Affiliation(s)
- Oliver P. Ernst
- Departments
of Biochemistry and Molecular Genetics, University of Toronto, 1 King’s College Circle, Medical Sciences Building, Toronto, Ontario M5S 1A8, Canada
| | - David T. Lodowski
- Center
for Proteomics and Bioinformatics, Case
Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Marcus Elstner
- Institute
for Physical Chemistry, Karlsruhe Institute
of Technology, Kaiserstrasse
12, 76131 Karlsruhe, Germany
| | - Peter Hegemann
- Institute
of Biology, Experimental Biophysics, Humboldt-Universität
zu Berlin, Invalidenstrasse
42, 10115 Berlin, Germany
| | - Leonid
S. Brown
- Department
of Physics and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada
| | - Hideki Kandori
- Department
of Frontier Materials, Nagoya Institute
of Technology, Showa-ku, Nagoya 466-8555, Japan
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40
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Affiliation(s)
| | | | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case
Western Reserve University, 2109 Adelbert Road, Cleveland, Ohio 44106-4965,
United States
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41
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Zhong M, Kawaguchi R, Kassai M, Sun H. Retina, retinol, retinal and the natural history of vitamin A as a light sensor. Nutrients 2012; 4:2069-96. [PMID: 23363998 PMCID: PMC3546623 DOI: 10.3390/nu4122069] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 11/27/2012] [Accepted: 11/28/2012] [Indexed: 02/07/2023] Open
Abstract
Light is both the ultimate energy source for most organisms and a rich information source. Vitamin A-based chromophore was initially used in harvesting light energy, but has become the most widely used light sensor throughout evolution from unicellular to multicellular organisms. Vitamin A-based photoreceptor proteins are called opsins and have been used for billions of years for sensing light for vision or the equivalent of vision. All vitamin A-based light sensors for vision in the animal kingdom are G-protein coupled receptors, while those in unicellular organisms are light-gated channels. This first major switch in evolution was followed by two other major changes: the switch from bistable to monostable pigments for vision and the expansion of vitamin A's biological functions. Vitamin A's new functions such as regulating cell growth and differentiation from embryogenesis to adult are associated with increased toxicity with its random diffusion. In contrast to bistable pigments which can be regenerated by light, monostable pigments depend on complex enzymatic cycles for regeneration after every photoisomerization event. Here we discuss vitamin A functions and transport in the context of the natural history of vitamin A-based light sensors and propose that the expanding functions of vitamin A and the choice of monostable pigments are the likely evolutionary driving forces for precise, efficient, and sustained vitamin A transport.
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Affiliation(s)
- Ming Zhong
- Department of Physiology, Jules Stein Eye Institute, and Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
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42
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Abstract
The chromophore of all known visual pigments consists of 11-cis-retinal (derived from either vitamin A1 or A2) or a hydroxylated derivative, bound to a protein (opsin) via a Schiff base. Absorption of a photon results in photoisomerization of the chromophore to all-trans-retinal and conversion of the visual pigment to the signaling form. Regeneration of the 11-cis-retinal occurs in an adjacent tissue and involves several enzymes, several water-soluble retinoid-binding proteins, and intra- and intercellular diffusional processes. Rod photoreceptor cells depend completely on the output of 11-cis-retinal from adjacent retinal pigment epithelial (RPE) cells. Cone photoreceptors cells can use 11-cis-retinal from the RPE and from a second more poorly characterized cycle, which appears to involve adjacent Müller (glial) cells. Recent progress in the characterization of rod and cone visual cycle components and reactions will result in the development of approaches to the amelioration of blinding eye diseases associated with visual cycle defects.
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Affiliation(s)
- John C Saari
- Department of Ophthalmology and Biochemistry, University of Washington, Seattle, WA 91895, USA.
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43
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Mason B, Schmale M, Gibbs P, Miller MW, Wang Q, Levay K, Shestopalov V, Slepak VZ. Evidence for multiple phototransduction pathways in a reef-building coral. PLoS One 2012; 7:e50371. [PMID: 23227169 PMCID: PMC3515558 DOI: 10.1371/journal.pone.0050371] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 10/19/2012] [Indexed: 12/31/2022] Open
Abstract
Photosensitive behaviors and circadian rhythms are well documented in reef-building corals and their larvae, but the mechanisms responsible for photoreception have not been described in these organisms. Here we report the cloning, immunolocalization, and partial biochemical characterization of three opsins and four G proteins expressed in planulae of the Caribbean elkhorn coral, Acropora palmata. All three opsins (acropsins 1-3) possess conserved seven-pass transmembrane structure, and localize to distinct regions of coral planulae. Acropsin 1 was localized in the larval endoderm, while acropsin 2 was localized in solitary cells of the ectoderm. These rod-like cells displayed a remarkably polarized distribution, concentrated in the aboral end. We also cloned four A. palmata G protein alpha subunits. Three were homologs of vertebrate Gi, Go, and Gq. The fourth is presumably a novel G protein, which displays only 40% identity with the nearest known G protein, and we termed it Gc for "cnidarian". We show that Gc and Gq can be activated by acropsins in a light-dependent manner in vitro. This indicates that at least acropsins 1 and 3 can form functional photoreceptors and potentially may play a role in color preference during settlement, vertical positioning and other light-guided behaviors observed in coral larvae.
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Affiliation(s)
- Benjamin Mason
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, United States of America
- * E-mail: (BM); (VZS)
| | - Michael Schmale
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, United States of America
| | - Patrick Gibbs
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, United States of America
| | - Margaret W. Miller
- National Marine Fisheries Service, Southeast Fisheries Science Center, Miami, Florida, United States of America
| | - Qiang Wang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Konstantin Levay
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Valery Shestopalov
- Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Vladlen Z. Slepak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- * E-mail: (BM); (VZS)
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44
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Chucair-Elliott AJ, Elliott MH, Wang J, Moiseyev GP, Ma JX, Politi LE, Rotstein NP, Akira S, Uematsu S, Ash JD. Leukemia inhibitory factor coordinates the down-regulation of the visual cycle in the retina and retinal-pigmented epithelium. J Biol Chem 2012; 287:24092-102. [PMID: 22645143 DOI: 10.1074/jbc.m112.378240] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Leukemia inhibitory factor (LIF), an interleukin-6 family neurocytokine, is up-regulated in response to different types of retinal stress and has neuroprotective activity through activation of the gp130 receptor/STAT3 pathway. We observed that LIF induces rapid, robust, and sustained activation of STAT3 in both the retina and retinal pigmented epithelium (RPE). Here, we tested whether LIF-induced STAT3 activation within the RPE can down-regulate RPE65, the central enzyme in the visual cycle that provides the 11-cis-retinal chromophore to photoreceptors in vivo. We generated conditional knock-out mice to specifically delete STAT3 or gp130 in RPE, retina, or both RPE and retina. After intravitreal injection of LIF, we analyzed the expression levels of visual cycle genes and proteins, isomerase activity of RPE65, levels of rhodopsin protein, and the rates of dark adaptation and rhodopsin regeneration. We found that RPE65 protein levels and isomerase activity were reduced and recovery of bleachable rhodopsin was delayed in LIF-injected eyes. In mice with functional gp130/STAT3 signaling in the retina, rhodopsin protein was also reduced by LIF. However, the LIF-induced down-regulation of RPE65 required a functional gp130/STAT3 cascade intrinsic to RPE. Our data demonstrate that a single cytokine, LIF, can simultaneously and independently affect both RPE and photoreceptors through the same signaling cascade to reduce the generation and utilization of 11-cis-retinal.
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Affiliation(s)
- Ana J Chucair-Elliott
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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Ruiz A, Mark M, Jacobs H, Klopfenstein M, Hu J, Lloyd M, Habib S, Tosha C, Radu RA, Ghyselinck NB, Nusinowitz S, Bok D. Retinoid content, visual responses, and ocular morphology are compromised in the retinas of mice lacking the retinol-binding protein receptor, STRA6. Invest Ophthalmol Vis Sci 2012; 53:3027-39. [PMID: 22467576 DOI: 10.1167/iovs.11-8476] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We report generation of a mouse model in which the STRA6 gene has been disrupted functionally to facilitate the study of visual responses, changes in ocular morphology, and retinoid processing under STRA6 protein deficiency. METHODS A null mouse line, stra6 -/-, was generated. Western Blot and immunocytochemistry were used to determine expression of STRA6 protein. Visual responses and morphological studies were performed on 6-week, 5-month and 10-month-old mice. The retinoid content of eye tissues was evaluated in dark-adapted mice by high performance liquid chromatography. RESULTS STRA6 protein was not detectable in stra6 -/- null mice, which had a consistent reduction, but not total ablation of their visual responses. The mice also showed significant depletion of their retinoid content in retinal pigment epithelium (RPE) and neurosensory retina, including a 95% reduction in retinyl esters. At the morphological level, a reduction in thickness of the neurosensory retina due to shortening of the rod outer and inner segments was observed when compared to control litter mates with a commensurate reduction in rod a- and b-wave amplitudes. In addition, there was a reduction in cone photoreceptor cell number and cone b-wave amplitude. A typical hallmark in stra6 -/- null eyes was the presence of a persistent primary hypertrophic vitreous, an optically dense vascularized structure located in the vitreous humor between the posterior surface of the lens and neurosensory retina. CONCLUSIONS Our studies of stra6 -/- null mice established the importance of the STRA6 protein for the uptake, intracellular transport, and processing of retinol by the RPE. In its absence, rod photoreceptor outer and inner segment length was reduced, and cone cell numbers were reduced, as were scotopic and photopic responses. STRA6 also was required for dissolution of the primary vitreous. However, it was clear from these studies that STRA6 is not the only pathway for retinol uptake by the RPE.
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Affiliation(s)
- Alberto Ruiz
- Department of Neurobiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA
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Expression of novel opsins and intrinsic light responses in the mammalian retinal ganglion cell line RGC-5. Presence of OPN5 in the rat retina. PLoS One 2011; 6:e26417. [PMID: 22022612 PMCID: PMC3195719 DOI: 10.1371/journal.pone.0026417] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 09/26/2011] [Indexed: 02/01/2023] Open
Abstract
The vertebrate retina is known to contain three classes of photoreceptor cells: cones and rods responsible for vision, and intrinsically photoresponsive retinal ganglion cells (RGCs) involved in diverse non-visual functions such as photic entrainment of daily rhythms and pupillary light responses. In this paper we investigated the potential intrinsic photoresponsiveness of the rat RGC line, RGC-5, by testing for the presence of visual and non-visual opsins and assessing expression of the immediate-early gene protein c-Fos and changes in intracellular Ca2+mobilization in response to brief light pulses. Cultured RGC-5 cells express a number of photopigment mRNAs such as retinal G protein coupled receptor (RGR), encephalopsin/panopsin (Opn3), neuropsin (Opn5) and cone opsin (Opn1mw) but not melanopsin (Opn4) or rhodopsin. Opn5 immunoreactivity was observed in RGC-5 cells and in the inner retina of rat, mainly localized in the ganglion cell layer (GCL). Furthermore, white light pulses of different intensities and durations elicited changes both in intracellular Ca2+ levels and in the induction of c-Fos protein in RGC-5 cell cultures. The results demonstrate that RGC-5 cells expressing diverse putative functional photopigments display intrinsic photosensitivity which accounts for the photic induction of c-Fos protein and changes in intracellular Ca2+ mobilization. The presence of Opn5 in the GCL of the rat retina suggests the existence of a novel type of photoreceptor cell.
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Sun H. Membrane receptors and transporters involved in the function and transport of vitamin A and its derivatives. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:99-112. [PMID: 21704730 DOI: 10.1016/j.bbalip.2011.06.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/01/2011] [Accepted: 06/10/2011] [Indexed: 12/12/2022]
Abstract
The eye is the human organ most sensitive to vitamin A deficiency because of vision's absolute and heavy dependence on vitamin A for light perception. Studies of the molecular basis of vision have provided important insights into the intricate mechanistic details of the function, transport and recycling of vitamin A and its derivatives (retinoid). This review focuses on retinoid-related membrane receptors and transporters. Three kinds of mammalian membrane receptors and transporters are discussed: opsins, best known as vitamin A-based light sensors in vision; ABCA4, an ATP-dependent transporter specializes in the transport of vitamin A derivative; and STRA6, a recently identified membrane receptor that mediates cellular uptake of vitamin A. The evolutionary driving forces for their existence and the wide spectrum of human diseases associated with these proteins are discussed. Lessons learned from the study of the visual system might be useful for understanding retinoid biology and retinoid-related diseases in other organ systems as well. This article is part of a Special Issue entitled Retinoid and Lipid Metabolism.
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Affiliation(s)
- Hui Sun
- Department of Physiology, Jules Stein Eye Institute, Brian Research Institute, and Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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48
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Schreiber R, Taschler U, Preiss-Landl K, Wongsiriroj N, Zimmermann R, Lass A. Retinyl ester hydrolases and their roles in vitamin A homeostasis. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:113-23. [PMID: 21586336 PMCID: PMC3242165 DOI: 10.1016/j.bbalip.2011.05.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/28/2011] [Accepted: 05/02/2011] [Indexed: 12/16/2022]
Abstract
In mammals, dietary vitamin A intake is essential for the maintenance of adequate retinoid (vitamin A and metabolites) supply of tissues and organs. Retinoids are taken up from animal or plant sources and subsequently stored in form of hydrophobic, biologically inactive retinyl esters (REs). Accessibility of these REs in the intestine, the circulation, and their mobilization from intracellular lipid droplets depends on the hydrolytic action of RE hydrolases (REHs). In particular, the mobilization of hepatic RE stores requires REHs to maintain steady plasma retinol levels thereby assuring constant vitamin A supply in times of food deprivation or inadequate vitamin A intake. In this review, we focus on the roles of extracellular and intracellular REHs in vitamin A metabolism. Furthermore, we will discuss the tissue-specific function of REHs and highlight major gaps in the understanding of RE catabolism. This article is part of a Special Issue entitled Retinoid and Lipid Metabolism.
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Lopes VS, Gibbs D, Libby RT, Aleman TS, Welch DL, Lillo C, Jacobson SG, Radu RA, Steel KP, Williams DS. The Usher 1B protein, MYO7A, is required for normal localization and function of the visual retinoid cycle enzyme, RPE65. Hum Mol Genet 2011; 20:2560-70. [PMID: 21493626 PMCID: PMC3110002 DOI: 10.1093/hmg/ddr155] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in the MYO7A gene cause a deaf-blindness disorder, known as Usher syndrome 1B. In the retina, the majority of MYO7A is in the retinal pigmented epithelium (RPE), where many of the reactions of the visual retinoid cycle take place. We have observed that the retinas of Myo7a-mutant mice are resistant to acute light damage. In exploring the basis of this resistance, we found that Myo7a-mutant mice have lower levels of RPE65, the RPE isomerase that has a key role in the retinoid cycle. We show for the first time that RPE65 normally undergoes a light-dependent translocation to become more concentrated in the central region of the RPE cells. This translocation requires MYO7A, so that, in Myo7a-mutant mice, RPE65 is partly mislocalized in the light. RPE65 is degraded more quickly in Myo7a-mutant mice, perhaps due to its mislocalization, providing a plausible explanation for its lower levels. Following a 50–60% photobleach, Myo7a-mutant retinas exhibited increased all-trans-retinyl ester levels during the initial stages of dark recovery, consistent with a deficiency in RPE65 activity. Lastly, MYO7A and RPE65 were co-immunoprecipitated from RPE cell lysate by antibodies against either of the proteins, and the two proteins were partly colocalized, suggesting a direct or indirect interaction. Together, the results support a role for MYO7A in the translocation of RPE65, illustrating the involvement of a molecular motor in the spatiotemporal organization of the retinoid cycle in vision.
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Affiliation(s)
- Vanda S Lopes
- Jules Stein Eye Institute and Department of Neurobiology, UCLA School of Medicine, University of California-Los Angeles, 200 Stein Plaza, Los Angeles, CA 90095, USA
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50
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Sparrow JR, Hicks D, Hamel CP. The retinal pigment epithelium in health and disease. Curr Mol Med 2011; 10:802-23. [PMID: 21091424 DOI: 10.2174/156652410793937813] [Citation(s) in RCA: 397] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 09/13/2010] [Indexed: 12/15/2022]
Abstract
Retinal pigment epithelial cells (RPE) constitute a simple layer of cuboidal cells that are strategically situated behind the photoreceptor (PR) cells. The inconspicuousness of this monolayer contrasts sharply with its importance [1]. The relationship between the RPE and PR cells is crucial to sight; this is evident from basic and clinical studies demonstrating that primary dysfunctioning of the RPE can result in visual cell death and blindness. RPE cells carry out many functions including the conversion and storage of retinoid, the phagocytosis of shed PR outer segment membrane, the absorption of scattered light, ion and fluid transport and RPE-PR apposition. The magnitude of the demands imposed on this single layer of cells in order to execute these tasks, will become apparent to the reader of this review as will the number of clinical disorders that take origin from these cells.
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Affiliation(s)
- J R Sparrow
- Department of Ophthalmology, Columbia University, New York, NY 10032, USA.
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