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Sparrow JR, Parmann R, Tsang SH, Allikmets R, Chang S, Jauregui R. Shared Features in Retinal Disorders With Involvement of Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2021; 62:15. [PMID: 34115091 PMCID: PMC8196415 DOI: 10.1167/iovs.62.7.15] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
When using spectral domain optical coherence tomography (SD-OCT) to inform the status of outer retina, we have noted discrete hyperreflective lesions extending through photoreceptor-attributable bands that have a similar presentation in multiple retinal diseases. These lesions present as either corrugated thickenings of interdigitation zone and ellipsoid zone bands or in later stages as rectangular or pyramidal shaped foci that extend radially through photoreceptor cell-attributable bands. In ABCA4-related and peripherin-2/RDS-disease (PRPH2/RDS), monogenic forms of retinopathy caused by mutations in proteins expressed in photoreceptor cells, these punctate lesions colocalize with fundus flecks in en face images. In fundus albipunctatus and retinitis punctata albescens, diseases caused by mutations in genes (retinol dehydrogenase 5, RDH5; and retinaldehyde-binding protein 1, RLBP1) encoding proteins of the visual cycle, these lesions manifest as white dot-like puncta. Similar aberrations in photoreceptor cell-attributable SD-OCT reflectivity layers manifest as reticular pseudodrusen (RPD) in short-wavelength fundus autofluorescence and near-infrared fundus autofluorescence fundus images and are linked to age-related macular degeneration a complex disease. Despite differences in the etiologies of retinal diseases presenting as fundus flecks, dots and RPD, underlying degenerative processes in photoreceptor cells are signified in SD-OCT scans by the loss of structural features that would otherwise define healthy photoreceptor cells at these foci.
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Affiliation(s)
- Janet R Sparrow
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States.,Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States
| | - Rait Parmann
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States
| | - Stephen H Tsang
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States.,Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States
| | - Rando Allikmets
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States.,Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States
| | - Stanley Chang
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States
| | - Ruben Jauregui
- Department of Ophthalmology, Harkness Eye Institute, Columbia University, New York, New York, United States
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Aryal S, Anand D, Hernandez FG, Weatherbee BAT, Huang H, Reddy AP, Wilmarth PA, David LL, Lachke SA. MS/MS in silico subtraction-based proteomic profiling as an approach to facilitate disease gene discovery: application to lens development and cataract. Hum Genet 2019; 139:151-184. [PMID: 31797049 DOI: 10.1007/s00439-019-02095-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 11/24/2019] [Indexed: 12/20/2022]
Abstract
While the bioinformatics resource-tool iSyTE (integrated Systems Tool for Eye gene discovery) effectively identifies human cataract-associated genes, it is currently based on just transcriptome data, and thus, it is necessary to include protein-level information to gain greater confidence in gene prioritization. Here, we expand iSyTE through development of a novel proteome-based resource on the lens and demonstrate its utility in cataract gene discovery. We applied high-throughput tandem mass spectrometry (MS/MS) to generate a global protein expression profile of mouse lens at embryonic day (E)14.5, which identified 2371 lens-expressed proteins. A major challenge of high-throughput expression profiling is identification of high-priority candidates among the thousands of expressed proteins. To address this problem, we generated new MS/MS proteome data on mouse whole embryonic body (WB). WB proteome was then used as a reference dataset for performing "in silico WB-subtraction" comparative analysis with the lens proteome, which effectively identified 422 proteins with lens-enriched expression at ≥ 2.5 average spectral counts, ≥ 2.0 fold enrichment (FDR < 0.01) cut-off. These top 20% candidates represent a rich pool of high-priority proteins in the lens including known human cataract-linked genes and many new potential regulators of lens development and homeostasis. This rich information is made publicly accessible through iSyTE (https://research.bioinformatics.udel.edu/iSyTE/), which enables user-friendly visualization of promising candidates, thus making iSyTE a comprehensive tool for cataract gene discovery.
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Affiliation(s)
- Sandeep Aryal
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA
| | - Deepti Anand
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA
| | - Francisco G Hernandez
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA
| | - Bailey A T Weatherbee
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA
| | - Hongzhan Huang
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, 19716, USA
| | - Ashok P Reddy
- Proteomics Shared Resource, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Phillip A Wilmarth
- Proteomics Shared Resource, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Larry L David
- Proteomics Shared Resource, Oregon Health and Science University, Portland, OR, 97239, USA
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Salil A Lachke
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA.
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, 19716, USA.
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Fakhoury O, Conrath J, Donnadieu B, Warrak R, Matonti F. Treatment of cystoid macular edema in homozygous twins with glutathione synthetase deficiency and retinal dystrophy. J Fr Ophtalmol 2018; 41:116-121. [DOI: 10.1016/j.jfo.2017.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 07/26/2017] [Accepted: 08/21/2017] [Indexed: 11/28/2022]
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Hashem HE, Abd El-Haleem MR, Amer MG, Bor’i A. Pomegranate protective effect on experimental ischemia/reperfusion retinal injury in rats (histological and biochemical study). Ultrastruct Pathol 2017; 41:346-357. [DOI: 10.1080/01913123.2017.1346737] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Hala E. Hashem
- Histology and Cell Biology Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt
| | - Manal R. Abd El-Haleem
- Histology and Cell Biology Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt
| | - Mona G. Amer
- Histology and Cell Biology Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt
| | - Ashraf Bor’i
- Ophthalmology Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt
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Li T, Lin Y, Gao H, Chen C, Zhu Y, Liu B, Lian Y, Li Y, Zhou W, Jiang H, Li H, Wu Q, Liang X, Jin C, Huang X, Lu L. Two heterozygous mutations identified in one Chinese patient with bilateral macular coloboma. Mol Med Rep 2017; 16:2505-2510. [PMID: 28677725 PMCID: PMC5548055 DOI: 10.3892/mmr.2017.6887] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 05/31/2017] [Indexed: 11/06/2022] Open
Abstract
Congenital macular coloboma is characterized by defined punched out atrophic lesions of the macula. The present study aimed to investigate the genetic alterations of one Chinese sporadic patient with bilateral large macular coloboma. Complete ophthalmic examinations, including best‑corrected visual acuity, slit‑lamp examination, fundus examination, fundus photograph and fundus fluorescein angiography imaging, Pentacam, and optical coherence tomography were performed on the patient. Genomic DNA was extracted from leukocytes in a peripheral blood sample collected from the patient, the patient's unaffected family members and from 200 unrelated control subjects from the same population. Next‑generation sequencing of the known genes involved in ocular disease was performed. The functional effects of the mutation were analyzed using Polymorphism Phenotyping (PolyPhen) and Sorting Intolerant From Tolerant (SIFT). One heterozygous bestrophin 1 (BEST1) mutation c.1037C>A (p.Pro346His, p.P346H) in exon 9 and one heterozygous regulating synaptic membrane exocytosis 1 (RIMS1) mutation c.3481A>G (p.Arg1161Gly, p.R1161G) in exon 23 were identified in the patient being investigated, but not in the unaffected family members or unrelated control subjects. Polyphen and SIFT predicted that the amino acid substitution p.P346H in the BEST1 protein is damaging. In addition, Polyphen predicted that the amino acid substitution p.R1161G in the RIM1 protein is damaging. The results of the current study have increased the mutation spectrums of BEST1 and RIMS1, and are valuable for improving the current genetic counseling process and developing novel therapeutic interventions for patients with macular coloboma.
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Affiliation(s)
- Tao Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Ying Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Hongbin Gao
- Department of Toxicology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
| | - Chuan Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Yi Zhu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Bingqian Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Yu Lian
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Yonghao Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Wenli Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Hongye Jiang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Sun Yat‑sen University, Guangzhou, Guangdong 510000, P.R. China
| | - Haichun Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Qingxiu Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Xiaoling Liang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Chenjin Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Xinhua Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
| | - Lin Lu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat‑sen University, Guangzhou, Guangdong 510060, P.R. China
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Siu AW, Shan SW, Li KK, Lam HY, Fung MY, Li KK, To CH, Do CW. Glutathione attenuates nitric oxide-induced retinal lipid and protein changes. Ophthalmic Physiol Opt 2015; 35:135-46. [DOI: 10.1111/opo.12198] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 12/30/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Andrew W. Siu
- Laboratory of Experimental Optometry; School of Optometry; The Hong Kong Polytechnic University; Hong Kong China
| | - Sze Wan Shan
- Laboratory of Experimental Optometry; School of Optometry; The Hong Kong Polytechnic University; Hong Kong China
| | - King Kit Li
- Laboratory of Experimental Optometry; School of Optometry; The Hong Kong Polytechnic University; Hong Kong China
| | - Hiu Yan Lam
- Laboratory of Experimental Optometry; School of Optometry; The Hong Kong Polytechnic University; Hong Kong China
| | - Man Yee Fung
- Laboratory of Experimental Optometry; School of Optometry; The Hong Kong Polytechnic University; Hong Kong China
| | - Ka Ki Li
- Laboratory of Experimental Optometry; School of Optometry; The Hong Kong Polytechnic University; Hong Kong China
| | - Chi Ho To
- Laboratory of Experimental Optometry; School of Optometry; The Hong Kong Polytechnic University; Hong Kong China
- State Key Laboratory of Ophthalmology; Zhongshan Ophthalmic Center; Sun Yat-sen University; Guangzhou China
| | - Chi Wai Do
- Laboratory of Experimental Optometry; School of Optometry; The Hong Kong Polytechnic University; Hong Kong China
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Şekeroğlu HT, Hismi B, Kadayifcilar S, Coskun T. Fundus autofluorescence and optical coherence tomography findings in glutathione synthetase deficiency. J AAPOS 2015; 19:80-2. [PMID: 25727596 DOI: 10.1016/j.jaapos.2014.09.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 08/14/2014] [Accepted: 09/02/2014] [Indexed: 11/18/2022]
Abstract
We report the autofluorescence pattern and optical coherence tomography (OCT) characteristics in a 6-year-old boy with glutathione synthetase deficiency. The patient underwent complete ophthalmological examination, including full-field electroretinography, visual evoked potentials, fundus autofluorescence, and OCT imaging. Electrophysiological studies showed time-delay and subnormal responses. Fundus autofluorescence imaging revealed increased parafoveal autofluorescence compared to normal, and OCT showed alteration of photoreceptor and retinal pigment epithelium layers in the parafoveal region.
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Affiliation(s)
- Hande Taylan Şekeroğlu
- Department of Ophthalmology, Hacettepe University Faculty of Medicine, 06100 Ankara, Turkey.
| | - Burcu Hismi
- Division of Metabolism and Nutrition, Department of Pediatrics, Hacettepe University Faculty of Medicine, 06100 Ankara, Turkey
| | - Sibel Kadayifcilar
- Department of Ophthalmology, Hacettepe University Faculty of Medicine, 06100 Ankara, Turkey
| | - Turgay Coskun
- Division of Metabolism and Nutrition, Department of Pediatrics, Hacettepe University Faculty of Medicine, 06100 Ankara, Turkey
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Calzia D, Barabino S, Bianchini P, Garbarino G, Oneto M, Caicci F, Diaspro A, Tacchetti C, Manni L, Candiani S, Ravera S, Morelli A, Enrico Traverso C, Panfoli I. New findings in ATP supply in rod outer segments: insights for retinopathies. Biol Cell 2013; 105:345-58. [PMID: 23659850 DOI: 10.1111/boc.201300003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 05/03/2013] [Indexed: 01/10/2023]
Abstract
BACKGROUND INFORMATION The rod outer segment (OS) is the specialised organelle where phototransduction takes place. Our previous proteomic and biochemical analyses on purified rod disks showed the functional expression of the respiratory chain complexes I-IV and F1 Fo -ATP synthase in OS disks, as well as active soluble tricarboxylic acid cycle enzymes. Here, we focussed our study on the whole OS that contains the cytosol and plasma membrane and disks as native flattened saccules, unlike spherical osmotically intact disks. RESULTS OS were purified from bovine retinas and characterised for purity. Oximetry, ATP synthesis and cytochrome c oxidase (COX) assays were performed. The presence of COX and F₁F₀-ATP synthase (ATP synthase) was assessed by semi-quantitative Western blotting, immunofluorescence or confocal laser scanning microscopy on whole bovine retinas and bovine retinal sections and by immunogold transmission electron microscopy (TEM) of purified OS or bovine retinal sections. Both ATP synthase and COX are catalytically active in OS. These are able to consume oxygen (O₂) in the presence of pyruvate and malate. CLSM analyses showed that rhodopsin autofluorescence and MitoTracker Deep Red 633 fluorescence co-localise on rod OS. Data are confirmed by co-localisation studies of ATP synthase with Rh in rod OS by immunofluorescence and TEM in bovine retinal sections. CONCLUSIONS Our data confirm the expression and activity of COX and ATP synthase in OS, suggestive of the presence of an extra-mitochondrial oxidative phosphorylation in rod OS, meant to supply ATP for the visual transduction. In this respect, the membrane rich OS environment would be meant to absorb both light and O₂. The ability of OS to manipulate O₂ may shed light on the pathogenesis of many retinal degenerative diseases ascribed to oxidative stress, as well as on the efficacy of the treatment with dietary supplements, presently utilised as supporting therapies.
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Affiliation(s)
- Daniela Calzia
- Department of Pharmacy-DIFAR, Biochemistry and Physiology Lab, University of Genoa, Genova, Italy
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Are rod outer segment ATP-ase and ATP-synthase activity expression of the same protein? Cell Mol Neurobiol 2013; 33:637-49. [PMID: 23568658 DOI: 10.1007/s10571-013-9926-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 03/12/2013] [Indexed: 12/15/2022]
Abstract
Vertebrate retinal rod outer segments (OS) consist of a stack of disks surrounded by the plasma membrane, where phototransduction takes place. Energetic metabolism in rod OS remains obscure. Literature described a so-called Mg(2+)-dependent ATPase activity, while our previous results demonstrated the presence of oxidative phosphorylation (OXPHOS) in OS, sustained by an ATP synthetic activity. Here we propose that the OS ATPase and ATP synthase are the expression of the same protein, i.e., of F1Fo-ATP synthase. Imaging on bovine retinal sections showed that some OXPHOS proteins are expressed in the OS. Biochemical data on bovine purified rod OS, characterized for purity, show an ATP synthase activity, inhibited by classical F1Fo-ATP synthase inhibitors. Moreover, OS possess a pH-dependent ATP hydrolysis, inhibited by pH values below 7, suggestive of the functioning of the inhibitor of F1 (IF1) protein. WB confirmed the presence of IF1 in OS, substantiating the expression of F1Fo ATP synthase in OS. Data suggest that the OS F1Fo ATP synthase is able to hydrolyze or synthesize ATP, depending on in vitro or in vivo conditions and that the role of IF1 would be pivotal in the prevention of the reversal of ATP synthase in OS, for example during hypoxia, granting photoreceptor survival.
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Lima VC, Rosen RB, Prata TS, Dorairaj S, Spielberg L, Maia M, Sallum JM. Association of age and macular pigment optical density using dual-wavelength autofluorescence imaging. Clin Ophthalmol 2013; 7:685-90. [PMID: 23589675 PMCID: PMC3622437 DOI: 10.2147/opth.s42549] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Background Several lines of evidence suggest that macular pigment may play a protective role against age-related macular degeneration, but the influence of age on macular pigment density levels remains unclear. This study was designed to investigate the relationship between age and the normal distribution of macular pigment optical density (MPOD) values surrounding the fovea. Methods Consecutive healthy subjects with no evidence of ocular disease were enrolled in this study. After inclusion, MPOD values were measured at specific eccentricities (0.5, 1, and 2 degrees) from the foveal center using a dual-wavelength autofluorescence method employing a modified confocal scanning laser ophthalmoscope. Whenever both eyes were eligible, one was randomly selected for analysis. The correlation between age and MPOD values was investigated using regression analysis. Results Thirty subjects (30 eyes) were included (mean age 48.6 ± 16.4 [range 23–77] years). Significant differences were found between MPOD values measured at 0.5, 1, and 2 degrees from the center of the fovea (0.49 ± 0.12 density units, 0.37 ± 0.11 density units, and 0.13 ± 0.05 density units, respectively, P < 0.05). Significant correlations between age and MPOD values at 0.5 and 1 degree were found (P ≤ 0.02). Values measured at 2 degrees did not correlate significantly with age (P = 0.06). Conclusion In healthy subjects, MPOD values were highest near the foveal center. These values appeared to increase during adulthood (peak at 45–50 years), followed by a gradual reduction after 60 years of age.
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Affiliation(s)
- Verônica Castro Lima
- Retina Service, Department of Ophthalmology, The New York Eye and Ear Infirmary, New York, NY ; Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
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Abstract
PURPOSE This study was designed to analyze macular tomography in patients of different ages with retinitis pigmentosa (RP) and correlate their visual function with macular thickness, which was measured by optical coherence tomography. METHODS In all, 75 RP patients and 75 controls were stratified into three age groups and macular thickness was measured by optical coherence tomography. The tomography was subdivided into three circular zones, four quadrants, and nine areas for analysis. Ophthalmic examinations, which involved ophthalmoscopic examinations, dark adaptation tests, visual acuities, visual field examinations, electrooculography, and color sense discrimination tests, were performed. RESULTS Macular thickness of the RP patients decreased in the middle age group (45- to 55-year old), whereas the oldest group showed an increased thickness. The thickness of the outer inferior area remained virtually unchanged, whereas the thickness of the inner temporal area showed the most fluctuation with age. In terms of circular sections, the most dramatic changes in macular thickness were observed in the fovea, and the aging effect decreased outward to the outer ring. Furthermore, the thickness of the fovea was more important than the thickness of the inner ring and the outer ring for electrooculography, visual acuity, and color sense discrimination in RP patients. CONCLUSIONS In middle age RP patients, the macular thickness decreased, whereas an increased thickness was observed in patients older than 55 years. In addition, the inner temporal area was the most fragile, and the outer inferior area was the least affected in patients with RP.
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Panfoli I, Calzia D, Ravera S, Morelli AM, Traverso CE. Extra-mitochondrial aerobic metabolism in retinal rod outer segments: new perspectives in retinopathies. Med Hypotheses 2012; 78:423-7. [PMID: 22284635 DOI: 10.1016/j.mehy.2011.12.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 12/06/2011] [Accepted: 12/29/2011] [Indexed: 01/11/2023]
Abstract
Vertebrate retinal rods are photoreceptors for dim-light vision. They display extreme sensitivity to light thanks to a specialized subcellular organelle, the rod outer segment. This is filled with a stack of membranous disks, expressing the proteins involved in visual transduction, a very energy demanding process. Our previous proteomic and biochemical studies have shed new light on the chemical energy processes that supply ATP to the outer segment, suggesting the presence of an extra-mitochondrial aerobic metabolism in rod outer segment, devoid of mitochondria, which would account for a quantitatively adequate ATP supply for phototransduction. Here the functional presence of an oxidative phosphorylation in the rod outer limb is examined for its relationship to many physiological and pathological data on the rod outer segment. We hypothesize that the rod outer limb is at risk of oxidative stress, in any case of impairment in the respiratory chain functioning, or of blood supply. In fact, the electron transfer chain is a major source of reactive O(2) species, known to produce severe alteration to the membrane lipids, especially those of the outer segment that are rich in polyunsaturated fatty acids. We propose that the disk membrane may become the target of reactive oxygen species that may be released by the electron transport chain under pathologic conditions. For example, during aging reactive oxygen species production increases, while cellular antioxidant capacity decreases. Also the apoptosis of the rod observed after exposure to bright or continuous illumination can be explained considering that an overfunctioning of phototransduction may damage the disk membrane to a point at which cytochrome c escapes from the intradiskal space, where it is presently supposed to be, activating a putative caspase 9 and the apoptosome. A pathogenic mechanism for many inherited and acquired retinal degenerations, representing a major problem in clinical ophthalmology, is proposed: a number of rod pathologies would be promoted by impairment of energy supply and/or oxidative stress in the rod outer segment. In conclusion we suppose that the damaging role of oxygen, be it hypoxia or hyperoxia invoked in most of the blinding diseases, acquired and even hereditary is to be seeked for inside the photoreceptor outer segment that would conceal a potential for cell death that is still to be recognized.
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Affiliation(s)
- I Panfoli
- DIPTERIS - University of Genova, Corso Europa 26, 16132 Genova, Italy.
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S-adenosyl-L-methionine restores photoreceptor function following acute retinal ischemia. Vis Neurosci 2009; 26:429-41. [PMID: 19919727 DOI: 10.1017/s0952523809990241] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The survival and function of retinal neurons is dependent on mitochondrial energy generation and its intracellular distribution by creatine kinase. Post ischemic disruption of retinal creatine synthesis, creatine kinase activity, or transport of creatine into neurons may impair retinal function. S-adenosyl-L-methionine (SAMe) is required for creatine synthesis, phosphatidylcholine and glutathione synthesis, and transducin methylation. These reactions are essential for photoreceptor function but may be downregulated after ischemia due to a reduction in SAMe. Our aim was to determine whether administration of SAMe after ischemia could improve retinal function. Unilateral retinal ischemia was induced in adult rats by increasing the intraocular pressure to 110 mm Hg for 60 min. Immediately after the ischemic insult, SAMe was injected into the vitreous (100 microM), followed by oral administration (69 mg/kg/day) for 5 or 10 days. Retinal function (electroretinography), histology, and creatine transporter (CRT-1) expression were analyzed. Photoreceptoral responses (R(mP3), S), rod and cone bipolar cell responses (PII), and oscillatory potentials were reduced by the ischemia/reperfusion insult. Although SAMe treatment ameliorated the ischemia-induced histological damage by day 5, there was no improvement in retinal function and the intensity of CRT-1 labeling in ischemic retinas was markedly reduced. However, 10 days after ischemia, a recovery in CRT-1 immunolabeling was evident and SAMe supplementation significantly restored photoreceptor function and rod PII responses. In conclusion, these data suggest that creatine transport and methylation reactions, such as creatine synthesis, may be compromised by an ischemic insult contributing to retinal dysfunction and injury. Oral SAMe supplementation after retinal ischemia may provide an effective, safe, and accessible neuroprotective strategy.
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