1
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Rajala RVS, Rajala A. Unlocking the role of lactate: metabolic pathways, signaling, and gene regulation in postmitotic retinal cells. FRONTIERS IN OPHTHALMOLOGY 2023; 3:1296624. [PMID: 38983010 PMCID: PMC11182115 DOI: 10.3389/fopht.2023.1296624] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 10/19/2023] [Indexed: 07/11/2024]
Abstract
The Warburg effect, which was first described a century ago, asserts that mitotic tumor cells generate higher quantities of lactate. Intriguingly, even in typical physiological circumstances, postmitotic retinal photoreceptor cells also produce elevated levels of lactate. Initially classified as metabolic waste, lactate has since gained recognition as a significant intracellular signaling mediator and extracellular ligand. This current review endeavors to provide a concise overview and discourse on the following topics: the localization of lactate-producing enzymes, the functional significance of these enzymes, the signaling functions of lactate, and its impact on the gene expression of photoreceptors in retinal cells.
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Affiliation(s)
- Raju V. S. Rajala
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Departments of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Departments of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Dean McGee Eye Institute, Oklahoma City, OK, United States
| | - Ammaji Rajala
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Dean McGee Eye Institute, Oklahoma City, OK, United States
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2
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Weh E, Goswami M, Chaudhury S, Fernando R, Miller N, Hager H, Sheskey S, Sharma V, Wubben TJ, Besirli CG. Metabolic Alterations Caused by Simultaneous Loss of HK2 and PKM2 Leads to Photoreceptor Dysfunction and Degeneration. Cells 2023; 12:2043. [PMID: 37626853 PMCID: PMC10453858 DOI: 10.3390/cells12162043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/04/2023] [Accepted: 08/08/2023] [Indexed: 08/27/2023] Open
Abstract
HK2 and PKM2 are two main regulators of aerobic glycolysis. Photoreceptors (PRs) use aerobic glycolysis to produce the biomass necessary for the daily renewal of their outer segments. Previous work has shown that HK2 and PKM2 are important for the normal function and long-term survival of PRs but are dispensable for PR maturation, and their individual loss has opposing effects on PR survival during acute nutrient deprivation. We generated double conditional (dcKO) mice lacking HK2 and PKM2 expression in rod PRs. Western blotting, immunofluorescence, optical coherence tomography, and electroretinography were used to characterize the phenotype of dcKO animals. Targeted and stable isotope tracing metabolomics, qRT-PCR, and retinal oxygen consumption were performed. We show that dcKO animals displayed early shortening of PR inner/outer segments, followed by loss of PRs with aging, much more rapidly than either knockout alone without functional loss as measured by ERG. Significant alterations to central glucose metabolism were observed without any apparent changes to mitochondrial function, prior to PR degeneration. Finally, PR survival following experimental retinal detachment was unchanged in dcKO animals as compared to wild-type animals. These data suggest that HK2 and PKM2 have differing roles in promoting PR neuroprotection and identifying them has important implications for developing therapeutic options for combating PR loss during retinal disease.
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Affiliation(s)
- Eric Weh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA; (M.G.); (S.C.); (R.F.); (N.M.); (H.H.); (S.S.); (V.S.); (T.J.W.)
| | | | | | | | | | | | | | | | | | - Cagri G. Besirli
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA; (M.G.); (S.C.); (R.F.); (N.M.); (H.H.); (S.S.); (V.S.); (T.J.W.)
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3
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Grumbine MK, Kamat V, Bao K, Crupi T, Mokate K, Lim R, Chao JR, Robbings BM, Hass DT, Hurley JB, Sweet IR. Maintaining and Assessing Various Tissue and Cell Types of the Eye Using a Novel Pumpless Fluidics System. J Vis Exp 2023:10.3791/65399. [PMID: 37522735 PMCID: PMC10791547 DOI: 10.3791/65399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023] Open
Abstract
Many in vitro models used to investigate tissue function and cell biology require a flow of media to provide adequate oxygenation and optimal cell conditions required for the maintenance of function and viability. Toward this end, we have developed a multi-channel flow culture system to maintain tissue and cells in culture and continuously assess function and viability by either in-line sensors and/or collection of outflow fractions. The system combines 8-channel, continuous optical sensing of oxygen consumption rate with a built-in fraction collector to simultaneously measure production rates of metabolites and hormone secretion. Although it is able to maintain and assess a wide range of tissue and cell models, including islets, muscle, and hypothalamus, here we describe its operating principles and the experimental preparations/protocols that we have used to investigate bioenergetic regulation of isolated mouse retina, mouse retinal pigment epithelium (RPE)-choroid-sclera, and cultured human RPE cells. Innovations in the design of the system, such as pumpless fluid flow, have produced a greatly simplified operation of a multi-channel flow system. Videos and images are shown that illustrate how to assemble, prepare the instrument for an experiment, and load the different tissue/cell models into the perifusion chambers. In addition, guidelines for selecting conditions for protocol- and tissue-specific experiments are delineated and discussed, including setting the correct flow rate to tissue ratio to obtain consistent and stable culture conditions and accurate determinations of consumption and production rates. The combination of optimal tissue maintenance and real-time assessment of multiple parameters yields highly informative data sets that will have great utility for research in the physiology of the eye and drug discovery for the treatment of impaired vision.
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Affiliation(s)
| | - Varun Kamat
- UW Medicine Diabetes Institute, University of Washington
| | | | | | - Kedar Mokate
- UW Medicine Diabetes Institute, University of Washington
| | - Rayne Lim
- Department of Ophthalmology, University of Washington
| | | | | | - Daniel T Hass
- Department of Biochemistry, University of Washington
| | | | - Ian R Sweet
- EnTox Sciences, Inc; UW Medicine Diabetes Institute, University of Washington;
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4
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Feng J, Zhang X, Li R, Zhao P, Han X, Wu Q, Tian Q, Tang G, Song J, Bi H. Widespread Involvement of Acetylation in the Retinal Metabolism of Form-Deprivation Myopia in Guinea Pigs. ACS OMEGA 2023; 8:23825-23839. [PMID: 37426266 PMCID: PMC10324097 DOI: 10.1021/acsomega.3c02219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 06/06/2023] [Indexed: 07/11/2023]
Abstract
Myopia has become the major cause of visual impairment worldwide. Although the pathogenesis of myopia remains controversial, proteomic studies suggest that dysregulation of retinal metabolism is potentially involved in the pathology of myopia. Lysine acetylation of proteins plays a key role in regulating cellular metabolism, but little is known about its role in the form-deprived myopic retina. Hence, a comprehensive analysis of proteomic and acetylomic changes in the retinas of guinea pigs with form-deprivation myopia was performed. In total, 85 significantly differential proteins and 314 significantly differentially acetylated proteins were identified. Notably, the differentially acetylated proteins were markedly enriched in metabolic pathways such as glycolysis/gluconeogenesis, the pentose phosphate pathway, retinol metabolism, and the HIF-1 signaling pathway. HK2, HKDC1, PKM, LDH, GAPDH, and ENO1 were the key enzymes in these metabolic pathways with decreased acetylation levels in the form-deprivation myopia group. Altered lysine acetylation of key enzymes in the form-deprived myopic retina might affect the dynamic balance of metabolism in the retinal microenvironment by altering their activity. In conclusion, as the first report on the myopic retinal acetylome, this study provides a reliable basis for further studies on myopic retinal acetylation.
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Affiliation(s)
- Jiaojiao Feng
- Shandong
University of Traditional Chinese Medicine, Jinan 250014, Shandong, China
| | - Xiuyan Zhang
- Affiliated
Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250002, Shandong, China
- Shandong
Provincial Key Laboratory of Integrated Traditional Chinese and Western
Medicine for Prevention and Therapy of Ocular Diseases, Shandong Academy of Eye Disease Prevention and Therapy, Jinan 250002, Shandong, China
| | - Runkuan Li
- Shandong
University of Traditional Chinese Medicine, Jinan 250014, Shandong, China
| | - Ping Zhao
- Affiliated
Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250002, Shandong, China
- Shandong
Provincial Key Laboratory of Integrated Traditional Chinese and Western
Medicine for Prevention and Therapy of Ocular Diseases, Shandong Academy of Eye Disease Prevention and Therapy, Jinan 250002, Shandong, China
| | - Xudong Han
- School
of Medicine, Southeast University, Nanjing 210009, Jiangsu, China
| | - Qiuxin Wu
- Affiliated
Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250002, Shandong, China
- Shandong
Provincial Key Laboratory of Integrated Traditional Chinese and Western
Medicine for Prevention and Therapy of Ocular Diseases, Shandong Academy of Eye Disease Prevention and Therapy, Jinan 250002, Shandong, China
| | - Qingmei Tian
- Affiliated
Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250002, Shandong, China
- Shandong
Provincial Key Laboratory of Integrated Traditional Chinese and Western
Medicine for Prevention and Therapy of Ocular Diseases, Shandong Academy of Eye Disease Prevention and Therapy, Jinan 250002, Shandong, China
| | - Guodong Tang
- Affiliated
Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250002, Shandong, China
- Shandong
Provincial Key Laboratory of Integrated Traditional Chinese and Western
Medicine for Prevention and Therapy of Ocular Diseases, Shandong Academy of Eye Disease Prevention and Therapy, Jinan 250002, Shandong, China
| | - Jike Song
- Shandong
University of Traditional Chinese Medicine, Jinan 250014, Shandong, China
- Affiliated
Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250002, Shandong, China
| | - Hongsheng Bi
- Affiliated
Eye Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250002, Shandong, China
- Shandong
Provincial Key Laboratory of Integrated Traditional Chinese and Western
Medicine for Prevention and Therapy of Ocular Diseases, Shandong Academy of Eye Disease Prevention and Therapy, Jinan 250002, Shandong, China
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5
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Wubben TJ, Chaudhury S, Watch BT, Stuckey JA, Weh E, Fernando R, Goswami M, Pawar M, Rech JC, Besirli CG. Development of Novel Small-Molecule Activators of Pyruvate Kinase Muscle Isozyme 2, PKM2, to Reduce Photoreceptor Apoptosis. Pharmaceuticals (Basel) 2023; 16:ph16050705. [PMID: 37242488 DOI: 10.3390/ph16050705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/01/2023] [Accepted: 05/04/2023] [Indexed: 05/28/2023] Open
Abstract
Treatment options are lacking to prevent photoreceptor death and subsequent vision loss. Previously, we demonstrated that reprogramming metabolism via the pharmacologic activation of PKM2 is a novel photoreceptor neuroprotective strategy. However, the features of the tool compound used in those studies, ML-265, preclude its advancement as an intraocular, clinical candidate. This study sought to develop the next generation of small-molecule PKM2 activators, aimed specifically for delivery into the eye. Compounds were developed that replaced the thienopyrrolopyridazinone core of ML-265 and modified the aniline and methyl sulfoxide functional groups. Compound 2 demonstrated that structural changes to the ML-265 scaffold are tolerated from a potency and efficacy standpoint, allow for a similar binding mode to the target, and circumvent apoptosis in models of outer retinal stress. To overcome the low solubility and problematic functional groups of ML-265, compound 2's efficacious and versatile core structure for the incorporation of diverse functional groups was then utilized to develop novel PKM2 activators with improved solubility, lack of structural alerts, and retained potency. No other molecules are in the pharmaceutical pipeline for the metabolic reprogramming of photoreceptors. Thus, this study is the first to cultivate the next generation of novel, structurally diverse, small-molecule PKM2 activators for delivery into the eye.
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Affiliation(s)
- Thomas J Wubben
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI 48105, USA
| | - Sraboni Chaudhury
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI 48105, USA
| | - Brennan T Watch
- Department of Internal Medicine, Hematology and Oncology, Michigan Center for Therapeutic Innovation, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jeanne A Stuckey
- Departments of Biological Chemistry and Biophysics, Center for Structural Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Eric Weh
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI 48105, USA
| | - Roshini Fernando
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI 48105, USA
| | - Moloy Goswami
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI 48105, USA
| | - Mercy Pawar
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI 48105, USA
| | - Jason C Rech
- Department of Internal Medicine, Hematology and Oncology, Michigan Center for Therapeutic Innovation, University of Michigan, Ann Arbor, MI 48109, USA
| | - Cagri G Besirli
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI 48105, USA
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6
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Csaky KG. Cross-Sectional Study of Cone Function in Age-Related Macular Degeneration Subjects With Non-foveal Nascent Geographic Atrophy. Am J Ophthalmol 2023; 247:25-34. [PMID: 36368346 DOI: 10.1016/j.ajo.2022.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 10/22/2022] [Accepted: 11/01/2022] [Indexed: 11/11/2022]
Abstract
PURPOSE To determine photoreceptor function in subjects with drusen only and non-foveal nascent geographic atrophy (nGA) intermediate age-related macular degeneration. METHODS In this cross-sectional study, 60 eyes from 33 subjects, 30 with drusen only and 30 with non-foveal nGA determined by spectral domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) underwent testing for best-corrected visual acuity (BCVA), low-luminance visual acuity (LLVA), and qCSF algorithm (area under log contrast sensitivity function [AULCSF]) under both standard photopic and low-luminance (LL AULCSF) conditions. Areas of nGA-associated hypo-autofluorescence (hypo-AF) were graded. RESULTS In the drusen group, visual acuity (VA) = 81 letters ± 3 (mean ± SD), LLVA = 65 letters ± 4, AULCSF = 0.99 ± 0.0.5, and LL AULCSF = 0.38 ± 0.04, whereas in the nGA group, VA = 77 ± 4 letters, LLVA = 61± 4, AULCSF = 0.87 ± 0.09, and LL AULCSF = 0.28 ± 0.06. Multivariate analysis of variance among the LLVA, AULCSF, and LL AULCSF did not demonstrate a statistical difference (P = .167), whereas LL AULCSF analyzed by analysis of variance demonstrated a significant difference between the 2 groups (P = .037). Linear regressions demonstrated significant relationships between BCVA and AULCSF in both the drusen and nGA groups (r = 0.83, P < 10-9 and r = 0.61, P = .0004) but did not correlate with AULCSF under low-luminance conditions (r = 2.9, P = .13) in the nGA group. The total area of hypo-AF was negatively associated with poorer visual functions. CONCLUSIONS The use of LL AULCSF and certain features of FAF should be considered in clinical trials of intermediate age-related macular degeneration. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
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Affiliation(s)
- Karl G Csaky
- From the Retina Foundation of the Southwest, Dallas, Texas, USA.
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7
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Ramírez-Pardo I, Villarejo-Zori B, Jiménez-Loygorri JI, Sierra-Filardi E, Alonso-Gil S, Mariño G, de la Villa P, Fitze PS, Fuentes JM, García-Escudero R, Ferrington DA, Gomez-Sintes R, Boya P. Ambra1 haploinsufficiency in CD1 mice results in metabolic alterations and exacerbates age-associated retinal degeneration. Autophagy 2023; 19:784-804. [PMID: 35875981 PMCID: PMC9980615 DOI: 10.1080/15548627.2022.2103307] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Macroautophagy/autophagy is a key process in the maintenance of cellular homeostasis. The age-dependent decline in retinal autophagy has been associated with photoreceptor degeneration. Retinal dysfunction can also result from damage to the retinal pigment epithelium (RPE), as the RPE-retina constitutes an important metabolic ecosystem that must be finely tuned to preserve visual function. While studies of mice lacking essential autophagy genes have revealed a predisposition to retinal degeneration, the consequences of a moderate reduction in autophagy, similar to that which occurs during physiological aging, remain unclear. Here, we described a retinal phenotype consistent with accelerated aging in mice carrying a haploinsufficiency for Ambra1, a pro-autophagic gene. These mice showed protein aggregation in the retina and RPE, metabolic underperformance, and premature vision loss. Moreover, Ambra1+/gt mice were more prone to retinal degeneration after RPE stress. These findings indicate that autophagy provides crucial support to RPE-retinal metabolism and protects the retina against stress and physiological aging.Abbreviations : 4-HNE: 4-hydroxynonenal; AMBRA1: autophagy and beclin 1 regulator 1, AMD: age-related macular degeneration;; GCL: ganglion cell layer; GFAP: glial fibrillary acidic protein; GLUL: glutamine synthetase/glutamate-ammonia ligase; HCL: hierarchical clustering; INL: inner nuclear layer; IPL: inner plexiform layer; LC/GC-MS: liquid chromatography/gas chromatography-mass spectrometry; MA: middle-aged; MTDR: MitoTracker Deep Red; MFI: mean fluorescence intensity; NL: NH4Cl and leupeptin; Nqo: NAD(P)H quinone dehydrogenase; ONL: outer nuclear layer; OPL: outer plexiform layer; OP: oscillatory potentials; OXPHOS: oxidative phosphorylation; PCR: polymerase chain reaction; PRKC/PKCα: protein kinase C; POS: photoreceptor outer segment; RGC: retinal ganglion cells; RPE: retinal pigment epithelium; SI: sodium iodate; TCA: tricarboxylic acid.
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Affiliation(s)
- Ignacio Ramírez-Pardo
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
| | - Beatriz Villarejo-Zori
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
| | - Juan Ignacio Jiménez-Loygorri
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
| | - Elena Sierra-Filardi
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
| | - Sandra Alonso-Gil
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
| | | | - Pedro de la Villa
- Department of Systems Biology, University of Alcalá, Alcalá de Henares, Madrid, Spain.,Vision neurophisiology group, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain
| | - Patrick S Fitze
- Departament of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain
| | - José Manuel Fuentes
- Department of Biochemistry, Molecular Biology and Genetics, Faculty of Nursing and Occupational Therapy, University of Extremadura, Cáceres, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Nerodegenerative Diseases unit, Instituto Universitario de Investigación Biosanitaria de Extremadura (INUBE), Cáceres, Spain
| | - Ramón García-Escudero
- Molecular Oncology Unit, CIEMAT, Madrid, Spain.,Biomedical Research Institute I+12, University Hospital 12 de Octubre, Madrid, Spain.,Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Madrid, Spain
| | - Deborah A Ferrington
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, USA
| | - Raquel Gomez-Sintes
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
| | - Patricia Boya
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Madrid, Spain
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8
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Arndt C, Hubault B, Hayate F, Barbe C, Afriat M, Gillery P, Ramont L, Henry A, Boulagnon-Rombi C. Increased intravitreal glucose in rhegmatogenous retinal detachment. Eye (Lond) 2023; 37:638-643. [PMID: 35273350 PMCID: PMC9998851 DOI: 10.1038/s41433-022-01968-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 01/22/2022] [Accepted: 02/02/2022] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Altered glucose metabolism, along with low-grade inflammation, has been proposed to be involved in retinal detachment (RD)-induced cone loss. Here, we assessed intravitreal glucose and cytological profile in patients with macula-off RD. METHODS Glucose concentration was analysed in vitreous samples from 137 non-diabetic patients undergoing vitrectomy for either primary macula-off RD (n = 73) or epiretinal membrane (ERM; n = 64). Cellularity was assessed in vitreous cytospin preparations by a semi-quantitative immunostaining approach. RESULTS Intravitreal glucose concentration was higher in the RD group (2.28 mmol.L-1 n =73 vs 1.6 mmol.L-1 n = 64; p < 0.0001). Overall cellularity and density of macrophages were significantly higher in the vitreous of RD patients (respectively p = 0.003 and p < 0.0001). Among the RD patients, intravitreal glucose concentration correlated with macrophages density (p = 0.002): its levels remained significantly higher in eyes in which macrophages were innumerable compared to lower macrophages densities RD eyes (p = 0.0095). CONCLUSIONS We observed a strong relationship between intravitreal glucose concentration and vitreous macrophage density. Additional indicators for vitreous glycation and low-grade inflammation should be further studied.
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Affiliation(s)
- Carl Arndt
- Department of Ophthalmology, Hôpital Robert Debré, Reims, France.
| | - Béatrice Hubault
- Department of Ophthalmology, Hôpital Robert Debré, Reims, France
| | - Fabien Hayate
- Department of Ophthalmology, Hôpital Robert Debré, Reims, France
- Department of Pathology, Hôpital Robert Debré, Reims, France
| | - Coralie Barbe
- Department of Clinical Research, Hôpital Robert Debré, Reims, France
| | - Mickaël Afriat
- Department of Ophthalmology, Hôpital Robert Debré, Reims, France
| | - Philippe Gillery
- Department of Biochemistry, Hôpital Robert Debré, Reims, France
- Research Unit CNRS UMR n°7369 MEDyC, Université de Reims Champagne-Ardenne, Faculté de Médecine de Reims, Reims, France
| | - Laurent Ramont
- Department of Biochemistry, Hôpital Robert Debré, Reims, France
- Research Unit CNRS UMR n°7369 MEDyC, Université de Reims Champagne-Ardenne, Faculté de Médecine de Reims, Reims, France
| | - Adrien Henry
- Department of Ophthalmology, Hôpital Robert Debré, Reims, France
- Research Unit CNRS UMR n°7369 MEDyC, Université de Reims Champagne-Ardenne, Faculté de Médecine de Reims, Reims, France
| | - Camille Boulagnon-Rombi
- Department of Pathology, Hôpital Robert Debré, Reims, France
- Research Unit CNRS UMR n°7369 MEDyC, Université de Reims Champagne-Ardenne, Faculté de Médecine de Reims, Reims, France
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9
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A Novel 5-Chloro- N-phenyl-1H-indole-2-carboxamide Derivative as Brain-Type Glycogen Phosphorylase Inhibitor: Validation of Target PYGB. Molecules 2023; 28:molecules28041697. [PMID: 36838691 PMCID: PMC9958726 DOI: 10.3390/molecules28041697] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 02/12/2023] Open
Abstract
Brain-type glycogen phosphorylase (PYGB) inhibitors are recognized as prospective drugs for treating ischemic brain injury. We previously reported compound 1 as a novel glycogen phosphorylase inhibitor with brain-protective properties. In this study, we validated whether PYGB could be used as the therapeutic target for hypoxic-ischemic diseases and investigated whether compound 1 exerts a protective effect against astrocyte hypoxia/reoxygenation (H/R) injury by targeting PYGB. A gene-silencing strategy was initially applied to downregulate PYGB proteins in mouse astrocytes, which was followed by a series of cellular experiments with compound 1. Next, we compared relevant indicators that could prove the protective effect of compound 1 on brain injury, finding that after PYGB knockdown, compound 1 could not obviously alleviate astrocytes H/R injury, as evidenced by cell viability, which was not significantly improved, and lactate dehydrogenase (LDH) leakage rate, intracellular glucose content, and post-ischemic reactive oxygen species (ROS) level, which were not remarkably reduced. At the same time, cellular energy metabolism did not improve, and the degree of extracellular acidification was not downregulated after administration of compound 1 after PYGB knockdown. In addition, it could neither significantly increase the level of mitochondrial aerobic energy metabolism nor inhibit the expression of apoptosis-associated proteins. The above results indicate that compound 1 could target PYGB to exert its protective effect against cellular H/R injury in mouse astrocytes. Simultaneously, we further demonstrated that PYGB could be an efficient therapeutic target for ischemic-hypoxic diseases. This study provides a new reference for further in-depth study of the action mechanism of the efficacy of compound 1.
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10
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Ciliary neurotrophic factor-mediated neuroprotection involves enhanced glycolysis and anabolism in degenerating mouse retinas. Nat Commun 2022; 13:7037. [PMID: 36396639 PMCID: PMC9672129 DOI: 10.1038/s41467-022-34443-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 10/25/2022] [Indexed: 11/18/2022] Open
Abstract
Ciliary neurotrophic factor (CNTF) acts as a potent neuroprotective cytokine in multiple models of retinal degeneration. To understand mechanisms underlying its broad neuroprotective effects, we have investigated the influence of CNTF on metabolism in a mouse model of photoreceptor degeneration. CNTF treatment improves the morphology of photoreceptor mitochondria, but also leads to reduced oxygen consumption and suppressed respiratory chain activities. Molecular analyses show elevated glycolytic pathway gene transcripts and active enzymes. Metabolomics analyses detect significantly higher levels of ATP and the energy currency phosphocreatine, elevated glycolytic pathway metabolites, increased TCA cycle metabolites, lipid biosynthetic pathway intermediates, nucleotides, and amino acids. Moreover, CNTF treatment restores the key antioxidant glutathione to the wild type level. Therefore, CNTF significantly impacts the metabolic status of degenerating retinas by promoting aerobic glycolysis and augmenting anabolic activities. These findings reveal cellular mechanisms underlying enhanced neuronal viability and suggest potential therapies for treating retinal degeneration.
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11
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Iwai S, Hasegawa T, Ikeda HO, Tsujikawa A. Branched Chain Amino Acids Promote ATP Production Via Translocation of Glucose Transporters. Invest Ophthalmol Vis Sci 2022; 63:7. [PMID: 35930269 PMCID: PMC9363681 DOI: 10.1167/iovs.63.9.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose We have previously shown that maintenance of ATP levels is a promising strategy for preventing neuronal cell death, and that branched chain amino acids (BCAAs) enhanced cellular ATP levels in cultured cells and antagonized cell death. BCAAs attenuated photoreceptor degeneration and retinal ganglion cell death in rodent models of retinal degeneration or glaucoma. This study aimed to elucidate the mechanisms through which BCAAs enhance ATP production. Methods Intracellular ATP concentration was measured in HeLa cells under glycolysis and citric acid cycle inhibited conditions. Next, glucose uptake was quantified in HeLa cells and in 661W retinal photoreceptor-derived cells under glycolysis inhibition, endoplasmic reticulum stress, and glucose transporters (GLUTs) inhibited conditions, by measuring the fluorescence of fluorescently labeled deoxy-glucose analog using flow cytometry. Then, the intracellular behavior of GLUT1 and GLUT3 were observed in HeLa or 661W cells transfected with enhanced green fluorescent protein-GLUTs. Results BCAAs recovered intracellular ATP levels during glycolysis inhibition and during citric acid cycle inhibition. BCAAs significantly increased glucose uptake and recovered decreased glucose uptake induced by endoplasmic reticulum stress or glycolysis inhibition. However, BCAAs were unable to increase intracellular ATP levels or glucose uptake when GLUTs were inhibited. Fluorescence microscopy revealed that supplementation of BCAAs enhanced the translocation of GLUTs proteins to the plasma membrane over time. Conclusions BCAAs increase ATP production by promoting glucose uptake through promotion of glucose transporters translocation to the plasma membrane. These results may help expand the clinical application of BCAAs in retinal neurodegenerative diseases, such as glaucoma and retinal degeneration.
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Affiliation(s)
- Sachiko Iwai
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Tomoko Hasegawa
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Research Fellow of the Japan Society for the Promotion of Science, Tokyo, Japan
| | - Hanako Ohashi Ikeda
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Akitaka Tsujikawa
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
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12
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Zhao X, Tebbe L, Naash MI, Al-Ubaidi MR. The Neuroprotective Role of Retbindin, a Metabolic Regulator in the Neural Retina. Front Pharmacol 2022; 13:919667. [PMID: 35873559 PMCID: PMC9298789 DOI: 10.3389/fphar.2022.919667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/10/2022] [Indexed: 11/13/2022] Open
Abstract
Dysregulation of retinal metabolism is emerging as one of the major reasons for many inherited retinal diseases (IRDs), a leading cause of blindness worldwide. Thus, the identification of a common regulator that can preserve or revert the metabolic ecosystem to homeostasis is a key step in developing a treatment for different forms of IRDs. Riboflavin (RF) and its derivatives (flavins), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), are essential cofactors for a wide range of cellular metabolic processes; hence, they are particularly critical in highly metabolically active tissues such as the retina. Patients with RF deficiency (ariboflavinosis) often display poor photosensitivity resulting in impaired low-light vision. We have identified a novel retina-specific RF binding protein called retbindin (Rtbdn), which plays a key role in retaining flavin levels in the neural retina. This role is mediated by its specific localization at the interface between the neural retina and retinal pigment epithelium (RPE), which is essential for metabolite and nutrient exchange. As a consequence of this vital function, Rtbdn's role in flavin utilization and metabolism in retinal degeneration is discussed. The principal findings are that Rtbdn helps maintain high levels of retinal flavins, and its ablation leads to an early-onset retinal metabolic dysregulation, followed by progressive degeneration of rod and cone photoreceptors. Lack of Rtbdn reduces flavin levels, forcing the neural retina to repurpose glucose to reduce the production of free radicals during ATP production. This leads to metabolic breakdown followed by retinal degeneration. Assessment of the role of Rtbdn in several preclinical retinal disease models revealed upregulation of its levels by several folds prior to and during the degenerative process. Ablation of Rtbdn in these models accelerated the rate of retinal degeneration. In agreement with these in vivo studies, we have also demonstrated that Rtbdn protects immortalized cone photoreceptor cells (661W cells) from light damage in vitro. This indicates that Rtbdn plays a neuroprotective role during retinal degeneration. Herein, we discussed the specific function of Rtbdn and its neuroprotective role in retinal metabolic homeostasis and its role in maintaining retinal health.
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Affiliation(s)
| | | | - Muna I. Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Muayyad R. Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
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13
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Aparicio A, Camacho ET, Philp NJ, Wirkus SA. A mathematical model of GLUT1 modulation in rods and RPE and its differential impact in cell metabolism. Sci Rep 2022; 12:10645. [PMID: 35739198 PMCID: PMC9226191 DOI: 10.1038/s41598-022-13950-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 05/31/2022] [Indexed: 11/10/2022] Open
Abstract
We present a mathematical model of key glucose metabolic pathways in two cells of the human retina: the rods and the retinal pigmented epithelium (RPE). Computational simulations of glucose transporter 1 (GLUT1) inhibition in the model accurately reproduce experimental data from conditional knockout mice and reveal that modification of GLUT1 expression levels of both cells differentially impacts their metabolism. We hypothesize that, under glucose scarcity, the RPE's energy producing pathways are altered in order to preserve its functionality, impacting the photoreceptors' outer segment renewal. On the other hand, when glucose is limited in the rods, aerobic glycolysis is preserved, which maintains the lactate contribution to the RPE.
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Affiliation(s)
- Andrea Aparicio
- School of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ, USA.
| | - Erika T Camacho
- School of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ, USA
| | - Nancy J Philp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Stephen A Wirkus
- School of Mathematical and Natural Sciences, Arizona State University, Glendale, AZ, USA
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14
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Peters F, Ebner LJA, Atac D, Maggi J, Berger W, den Hollander AI, Grimm C. Regulation of ABCA1 by AMD-Associated Genetic Variants and Hypoxia in iPSC-RPE. Int J Mol Sci 2022; 23:ijms23063194. [PMID: 35328615 PMCID: PMC8953808 DOI: 10.3390/ijms23063194] [Citation(s) in RCA: 4] [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: 02/23/2022] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 02/04/2023] Open
Abstract
Age-related macular degeneration (AMD) is a progressive disease of the macula characterized by atrophy of the retinal pigment epithelium (RPE) and photoreceptor degeneration, leading to severe vision loss at advanced stages in the elderly population. Impaired reverse cholesterol transport (RCT) as well as intracellular lipid accumulation in the RPE are implicated in AMD pathogenesis. Here, we focus on ATP-binding cassette transporter A1 (ABCA1), a major cholesterol transport protein in the RPE, and analyze conditions that lead to ABCA1 dysregulation in induced pluripotent stem cell (iPSC)-derived RPE cells (iRPEs). Our results indicate that the risk-conferring alleles rs1883025 (C) and rs2740488 (A) in ABCA1 are associated with increased ABCA1 mRNA and protein levels and reduced efficiency of cholesterol efflux from the RPE. Hypoxia, an environmental risk factor for AMD, reduced expression of ABCA1 and increased intracellular lipid accumulation. Treatment with a liver X receptor (LXR) agonist led to an increase in ABCA1 expression and reduced lipid accumulation. Our data strengthen the homeostatic role of cholesterol efflux in the RPE and suggest that increasing cellular cholesterol export by stimulating ABCA1 expression might lessen lipid load, improving RPE survival and reducing the risk of developing AMD.
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Affiliation(s)
- Florian Peters
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, 8952 Zurich, Switzerland;
- Correspondence: (F.P.); (C.G.)
| | - Lynn J. A. Ebner
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, 8952 Zurich, Switzerland;
| | - David Atac
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Zurich, Switzerland; (D.A.); (J.M.); (W.B.)
| | - Jordi Maggi
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Zurich, Switzerland; (D.A.); (J.M.); (W.B.)
| | - Wolfgang Berger
- Institute of Medical Molecular Genetics, University of Zurich, 8952 Zurich, Switzerland; (D.A.); (J.M.); (W.B.)
| | - Anneke I. den Hollander
- Department of Ophthalmology, Radboud University Medical Center, 6525 Nijmegen, The Netherlands;
- AbbVie, Genomic Research Center, 200 Sidney Street, Cambridge, MA 02139, USA
| | - Christian Grimm
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, 8952 Zurich, Switzerland;
- Correspondence: (F.P.); (C.G.)
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15
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Insights into pathological mechanisms and interventions revealed by analyzing a mathematical model for cone metabolism. Biosci Rep 2022; 42:230791. [PMID: 35156683 PMCID: PMC8905305 DOI: 10.1042/bsr20212457] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/14/2022] [Accepted: 02/11/2022] [Indexed: 11/17/2022] Open
Abstract
This work analyzes a mathematical model for the metabolic dynamics of a cone photoreceptor, which is the first model to account for energy generation from fatty acids oxidation of shed photoreceptor outer segments (POS). Multiple parameter bifurcation analysis shows that joint variations in external glucose, the efficiency of glucose transporter 1 (GLUT1), lipid utilization for POS renewal, and oxidation of fatty acids affect the cone’s metabolic vitality and its capability to adapt under glucose-deficient conditions. The analysis further reveals that when glucose is scarce, cone viability cannot be sustained by only fueling energy production in the mitochondria, but it also requires supporting anabolic processes to create lipids necessary for cell maintenance and repair. In silico experiments are used to investigate how the duration of glucose deprivation impacts the cell without and with a potential GLUT1 or oxidation of fatty acids intervention as well as a dual intervention. The results show that for prolonged duration of glucose deprivation, the cone metabolic system does not recover with higher oxidation of fatty acids and requires greater effectiveness of GLUT1 to recover. Finally, time-varying global sensitivity analysis (GSA) is applied to assess the sensitivity of the model outputs of interest to changes and uncertainty in the parameters at specific times. The results reveal a critical temporal window where there would be more flexibility for interventions to rescue a cone cell from the detrimental consequences of glucose shortage.
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16
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He J, Yamamoto M, Sumiyama K, Konagaya Y, Terai K, Matsuda M, Sato S. Two-photon AMPK and ATP imaging reveals the bias between rods and cones in glycolysis utility. FASEB J 2021; 35:e21880. [PMID: 34449091 DOI: 10.1096/fj.202101121r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/08/2021] [Accepted: 08/11/2021] [Indexed: 12/15/2022]
Abstract
In vertebrates, retinal rod and cone photoreceptor cells rely significantly on glycolysis. Lactate released from photoreceptor cells fuels neighboring retinal pigment epithelium cells and Müller glial cells through oxidative phosphorylation. To understand this highly heterogeneous metabolic environment around photoreceptor cells, single-cell analysis is needed. Here, we visualized cellular AMP-activated protein kinase (AMPK) activity and ATP levels in the retina by two-photon microscopy. Transgenic mice expressing a hyBRET-AMPK biosensor were used for measuring the AMPK activity. GO-ATeam2 transgenic mice were used for measuring the ATP level. Temporal metabolic responses were successfully detected in the live retinal explants upon drug perfusion. A glycolysis inhibitor, 2-deoxy-d-glucose (2-DG), activated AMPK and reduced ATP. These effects were clearly stronger in rods than in cones. Notably, rod AMPK and ATP started to recover at 30 min from the onset of 2-DG perfusion. Consistent with these findings, ex vivo electroretinogram recordings showed a transient slowdown in rod dim flash responses during a 60-min 2-DG perfusion, whereas cone responses were not affected. Based on these results, we propose that cones surrounded by highly glycolytic rods become less dependent on glycolysis, and rods also become less dependent on glycolysis within 60 min upon the glycolysis inhibition.
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Affiliation(s)
- Jiazhou He
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Masamichi Yamamoto
- Department of Research Promotion and Management, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Kenta Sumiyama
- Laboratory for Mouse Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Osaka, Japan
| | - Yumi Konagaya
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Kenta Terai
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Michiyuki Matsuda
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan.,Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, Japan
| | - Shinya Sato
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
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17
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GSH-Independent Induction of ER Stress during Hypoglycaemia in the Retinal Cells of Mice. J Clin Med 2021; 10:jcm10112529. [PMID: 34200353 PMCID: PMC8201117 DOI: 10.3390/jcm10112529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/31/2021] [Accepted: 06/04/2021] [Indexed: 11/17/2022] Open
Abstract
Glucose is one of the most important metabolic substrates of the retina, and glycaemic imbalances can lead to serious side effects, including retinopathy. We previously showed that hypoglycaemia induces retinal cell death in mice, as well as the implication of glutathione (GSH) in this process. This study aimed to analyse the role of low glucose-induced decrease in GSH levels in endoplasmic reticulum (ER) stress. We cultured 661W photoreceptor-like cells under various glucose conditions and analysed ER stress markers at the mRNA and protein levels. We used the ERAI (“ER stress-activated indicator”) mouse model to test ER stress in both ex vivo, on retinal explants, or in vivo, in mice subjected to hypoglycaemia. Moreover, we used buthionine sulfoximine (BSO) and glutamate cysteine ligase (Gclm)-KO mice as models of low GSH to test its effects on ER stress. We show that the unfolded protein response (UPR) is triggered in 661W cells and in ERAI mice under hypoglycaemic conditions. Low GSH levels promote cell death, but have no impact on ER stress. We concluded that low glucose levels induce ER stress independently of GSH levels. Inhibition of ER stress could prevent neurodegeneration, which seems to be an early event in the pathogenesis of diabetic retinopathy.
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18
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Sagmeister S, Merl-Pham J, Petrera A, Deeg CA, Hauck SM. High glucose treatment promotes extracellular matrix proteome remodeling in Mller glial cells. PeerJ 2021; 9:e11316. [PMID: 34046254 PMCID: PMC8139267 DOI: 10.7717/peerj.11316] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 03/30/2021] [Indexed: 11/20/2022] Open
Abstract
Background The underlying pathomechanisms in diabetic retinopathy (DR) remain incompletely understood. The aim of this study was to add to the current knowledge about the particular role of retinal Mller glial cells (RMG) in the initial processes of DR. Methods Applying a quantitative proteomic workflow, we investigated changes of primary porcine RMG under short term high glucose treatment as well as glycolysis inhibition treatment. Results We revealed significant changes in RMG proteome primarily in proteins building the extracellular matrix (ECM) indicating fundamental remodeling processes of ECM as novel rapid response to high glucose treatment. Among others, Osteopontin (SPP1) as well as its interacting integrins were significantly downregulated and organotypic retinal explant culture confirmed the selective loss of SPP1 in RMG upon treatment. Since SPP1 in the retina has been described neuroprotective for photoreceptors and functions against experimentally induced cell swelling, its rapid loss under diabetic conditions may point to a direct involvement of RMG to the early neurodegenerative processes driving DR. Data are available via ProteomeXchange with identifier PXD015879.
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Affiliation(s)
- Sandra Sagmeister
- Chair of Physiology, Department of Veterinary Sciences, LMU Munich, Martinsried, Germany.,Research Unit Protein Science and Metabolomics and Proteomics Core Facility, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Munich, Germany
| | - Juliane Merl-Pham
- Research Unit Protein Science and Metabolomics and Proteomics Core Facility, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Munich, Germany
| | - Agnese Petrera
- Research Unit Protein Science and Metabolomics and Proteomics Core Facility, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Munich, Germany
| | - Cornelia A Deeg
- Chair of Physiology, Department of Veterinary Sciences, LMU Munich, Martinsried, Germany
| | - Stefanie M Hauck
- Research Unit Protein Science and Metabolomics and Proteomics Core Facility, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Munich, Germany
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19
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Beeson C, Peterson YK, Perron N, Bandyopadhyay M, Nasarre C, Beeson G, Comer RF, Lindsey CC, Schnellmann RG, Rohrer B. Newly Identified Chemicals Preserve Mitochondrial Capacity and Decelerate Loss of Photoreceptor Cells in Murine Retinal Degeneration Models. J Ocul Pharmacol Ther 2021; 37:367-378. [PMID: 33945330 DOI: 10.1089/jop.2020.0140] [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: 01/15/2023] Open
Abstract
Purpose: Metabolic stress and associated mitochondrial dysfunction are implicated in retinal degeneration irrespective of the underlying cause. We identified seven unique chemicals from a Chembridge DiverSET screen and tested their protection against photoreceptor cell death in cell- and animal-based approaches. Methods: Calcium overload (A23187) was triggered in 661W murine photoreceptor-derived cells, and changes in redox potential and real-time changes in cellular metabolism were assessed using the MTT and Seahorse Biosciences XF assay, respectively. Cheminformatics to compare structures, and biodistribution in the living pig eye aided in selection of the lead compound. In-situ, retinal organ cultures of rd1 mouse and S334ter-line-3 rat were tested, in-vivo the light-induced retinal degeneration in albino Balb/c mice was used, assessing photoreceptor cell numbers histologically. Results: Of the seven chemicals, six were protective against A23187- and IBMX-induced loss of mitochondrial capacity, as measured by viability and respirometry in 661W cells. Cheminformatic analyses identified a unique pharmacophore with 6 physico-chemical features based on two compounds (CB11 and CB12). The protective efficacy of CB11 was further shown by reducing photoreceptor cell loss in retinal explants from two retinitis pigmentosa rodent models. Using eye drops, CB11 targeting to the pig retina was confirmed. The same eye drops decreased photoreceptor cell loss in light-stressed Balb/c mice. Conclusions: New chemicals were identified that protect from mitochondrial damage and lead to improved mitochondrial function. Using ex-vivo and in-vivo models, CB11 decreased the loss of photoreceptor cells in murine models of retinal degeneration and may be effective as treatment for different retinal dystrophies.
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Affiliation(s)
- Craig Beeson
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Yuri K Peterson
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Nathan Perron
- Department of Ophthalmology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Mausumi Bandyopadhyay
- Department of Ophthalmology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Cecile Nasarre
- Department of Ophthalmology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Gyda Beeson
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Richard F Comer
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Christopher C Lindsey
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Rick G Schnellmann
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona, USA.,Research Service, Southern Arizona VA Healthcare System, Tucson, Arizona, USA
| | - Bärbel Rohrer
- Department of Ophthalmology, Medical University of South Carolina, Charleston, South Carolina, USA.,Research Service, Ralph H Johnson VA Medical Center, Charleston, South Carolina, USA
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20
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Wang Z, Ji S, Huang Y, Liao K, Cui Z, Chu F, Chen J, Tang S. The daily gene transcription cycle in mouse retina. Exp Eye Res 2021; 207:108565. [PMID: 33838143 DOI: 10.1016/j.exer.2021.108565] [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] [Received: 12/16/2020] [Revised: 03/23/2021] [Accepted: 03/30/2021] [Indexed: 12/13/2022]
Abstract
Many physiological retinal processes, such as outer segment disk shedding and visual sensitivity, exhibit a daily rhythm. However, the detailed transcriptome dynamics and related biological processes of the retina are not fully understood. Retinal tissues were collected from C57BL/6J male mice housed in a 12h light/12h dark (LD) cycle for 4 weeks, at Zeitgeber time (ZT) 0, 4, 8, 12, 16, and 20. Total RNA was extracted from the tissues and used for unique identifier RNA sequencing experiments. The rhythmicity of gene expression was determined using the MetaCycle R package. We found that 1741 genes (10.26%) were rhythmically expressed in the retina. According to the expression patterns, the rhythmically expressed genes were assigned to four clusters, each with about 361-492 genes, using the Mfuzz R package. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses were conducted to identify pathways and biological processes of the profiled genes. Genes in Clusters 1 and 4 were associated with glycolysis and energy production, showed higher activity at night (from ZT16 to ZT20), and were enriched in the Hif-1α signaling pathway and low-oxygen-related terms. Genes in Cluster 2 were predominantly involved in cilium assembly and organization and were relatively upregulated during the day. Genes in Cluster 3 were associated with ribosome biosynthesis and were highly expressed during the day-night transition period. Taken together, these results demonstrate that a large proportion of retinal genes are expressed rhythmically. Genes involved in energy production and glycolysis are highly expressed at night, leading to relative hypoxia and activation of the Hif-1α signaling pathway. Genes associated with the formation of photoreceptor cilia are expressed during the day.
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Affiliation(s)
- Zhijie Wang
- Aier School of Ophthalmology, Central South University, Changsha, China; Aier Eye Institute, Changsha, China
| | | | - Yinhua Huang
- Aier School of Ophthalmology, Central South University, Changsha, China; Aier Eye Institute, Changsha, China
| | - Kai Liao
- Aier School of Ophthalmology, Central South University, Changsha, China; Aier Eye Institute, Changsha, China
| | | | - Feixue Chu
- Hangzhou Xihu Zhijiang Eye Hospital, China
| | - Jiansu Chen
- Aier School of Ophthalmology, Central South University, Changsha, China; Aier Eye Institute, Changsha, China; Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China; Institute of Ophthalmology, Medical College, Jinan University, Guangzhou, China.
| | - Shibo Tang
- Aier School of Ophthalmology, Central South University, Changsha, China; Aier Eye Institute, Changsha, China; CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.
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21
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Perron NR, Nasarre C, Bandyopadhyay M, Beeson CC, Rohrer B. SAHA is neuroprotective in in vitro and in situ models of retinitis pigmentosa. Mol Vis 2021; 27:151-160. [PMID: 33907370 PMCID: PMC8056468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 03/31/2021] [Indexed: 10/25/2022] Open
Abstract
PURPOSE Recent reports linking HDAC6 to mitochondrial turnover and neurodegeneration led us to hypothesize that an inhibitor such as Vorinostat (suberoylanilide hydroxamic acid, SAHA) may reduce mitochondrial damage found in retinitis pigmentosa (RP), a progressive neurodegenerative disease of the eye. Here we tested the efficacy of SAHA for its ability to protect photoreceptors in in-vitro and in-situ models of RP. As the stressor, we focused on calcium overload. Calcium is one of the main drivers of cell death, and is associated with rod loss in the rd1 mouse retina, which harbors a mutation in the Pde6b gene similar to that found in human patients suffering from autosomal recessive RP. METHOD Murine photoreceptor cell line (661W) were exposed to agents that led to calcium stress. Cell survival and redox capacity were measured using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, real-time changes in cellular metabolism were assessed using the Seahorse Biosciences XF24 analyzer, and mitochondrial fission-fusion using imaging. In-situ, neuroprotection was assessed in RPE/retina organ cultures of the rd1 mouse. SAHA effects on cell survival were compared in 661W cells with those of the specific HDAC6 inhibitor tubastatin A, and those on protein acetylation by Western blotting. RESULTS In stressed 661W cells, SAHA was found to increase cell survival that was associated with improved mitochondrial respiration and reduced mitochondrial fission. The protective effects of SAHA were also observed on photoreceptor cell survival in whole retinal organ explants of the rd1 mouse. Even though tubastatin A was ineffective in increasing cell survival in 661W cells, HDAC6 activity was confirmed in 661W cells after SAHA treatment with protein acetylation specific for HDAC6, defined by an increase in tubulin, but not histone acetylation. CONCLUSIONS SAHA was found to protect mitochondria from damage, and concomitantly reduced photoreceptor cell death in cell and organ cultures. The lack of activity of tubastatin A suggests that there must be an additional mechanism of action involved in the protective mechanism of SAHA that is responsible for its neuroprotection. Overall, SAHA may be a useful treatment for the prevention of photoreceptor degeneration associated with human RP. The results are discussed in the context of the effects of inhibitors that target different classes and members of the HDAC family and their effects on rod versus cone survival.
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Affiliation(s)
- Nathan R. Perron
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC
| | - Cécile Nasarre
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC
| | | | - Craig C. Beeson
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC
| | - Baerbel Rohrer
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC,Research Service, Ralph H Johnson VA Medical Center, Charleston, SC
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22
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Liu H, Prokosch V. Energy Metabolism in the Inner Retina in Health and Glaucoma. Int J Mol Sci 2021; 22:ijms22073689. [PMID: 33916246 PMCID: PMC8036449 DOI: 10.3390/ijms22073689] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/22/2021] [Accepted: 03/29/2021] [Indexed: 02/07/2023] Open
Abstract
Glaucoma, the leading cause of irreversible blindness, is a heterogeneous group of diseases characterized by progressive loss of retinal ganglion cells (RGCs) and their axons and leads to visual loss and blindness. Risk factors for the onset and progression of glaucoma include systemic and ocular factors such as older age, lower ocular perfusion pressure, and intraocular pressure (IOP). Early signs of RGC damage comprise impairment of axonal transport, downregulation of specific genes and metabolic changes. The brain is often cited to be the highest energy-demanding tissue of the human body. The retina is estimated to have equally high demands. RGCs are particularly active in metabolism and vulnerable to energy insufficiency. Understanding the energy metabolism of the inner retina, especially of the RGCs, is pivotal for understanding glaucoma’s pathophysiology. Here we review the key contributors to the high energy demands in the retina and the distinguishing features of energy metabolism of the inner retina. The major features of glaucoma include progressive cell death of retinal ganglions and optic nerve damage. Therefore, this review focuses on the energetic budget of the retinal ganglion cells, optic nerve and the relevant cells that surround them.
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Jaroszynska N, Harding P, Moosajee M. Metabolism in the Zebrafish Retina. J Dev Biol 2021; 9:10. [PMID: 33804189 PMCID: PMC8006245 DOI: 10.3390/jdb9010010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 03/08/2021] [Accepted: 03/11/2021] [Indexed: 12/12/2022] Open
Abstract
Retinal photoreceptors are amongst the most metabolically active cells in the body, consuming more glucose as a metabolic substrate than even the brain. This ensures that there is sufficient energy to establish and maintain photoreceptor functions during and after their differentiation. Such high dependence on glucose metabolism is conserved across vertebrates, including zebrafish from early larval through to adult retinal stages. As the zebrafish retina develops rapidly, reaching an adult-like structure by 72 hours post fertilisation, zebrafish larvae can be used to study metabolism not only during retinogenesis, but also in functionally mature retinae. The interplay between rod and cone photoreceptors and the neighbouring retinal pigment epithelium (RPE) cells establishes a metabolic ecosystem that provides essential control of their individual functions, overall maintaining healthy vision. The RPE facilitates efficient supply of glucose from the choroidal vasculature to the photoreceptors, which produce metabolic products that in turn fuel RPE metabolism. Many inherited retinal diseases (IRDs) result in photoreceptor degeneration, either directly arising from photoreceptor-specific mutations or secondary to RPE loss, leading to sight loss. Evidence from a number of vertebrate studies suggests that the imbalance of the metabolic ecosystem in the outer retina contributes to metabolic failure and disease pathogenesis. The use of larval zebrafish mutants with disease-specific mutations that mirror those seen in human patients allows us to uncover mechanisms of such dysregulation and disease pathology with progression from embryonic to adult stages, as well as providing a means of testing novel therapeutic approaches.
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Affiliation(s)
| | - Philippa Harding
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK;
| | - Mariya Moosajee
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK;
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
- The Francis Crick Institute, London NW1 1AT, UK
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Murenu E, Kostidis S, Lahiri S, Geserich AS, Imhof A, Giera M, Michalakis S. Metabolic Analysis of Vitreous/Lens and Retina in Wild Type and Retinal Degeneration Mice. Int J Mol Sci 2021; 22:ijms22052345. [PMID: 33652907 PMCID: PMC7956175 DOI: 10.3390/ijms22052345] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/19/2021] [Accepted: 02/23/2021] [Indexed: 02/06/2023] Open
Abstract
Photoreceptors are the light-sensing cells of the retina and the major cell type affected in most inherited retinal degenerations. Different metabolic pathways sustain their high energetic demand in physiological conditions, particularly aerobic glycolysis. The principal metabolome of the mature retina has been studied, but only limited information is available on metabolic adaptations in response to key developmental events, such as eye opening. Moreover, dynamic metabolic changes due to retinal degeneration are not well understood. Here, we aimed to explore and map the ocular metabolic dynamics induced by eye opening in healthy (wild type) or Pde6b-mutant (retinal degeneration 1, Rd1) mice, in which photoreceptors degenerate shortly after eye opening. To unravel metabolic differences emerging before and after eye opening under physiological and pathophysiological conditions, we performed nuclear magnetic resonance (NMR) spectroscopy-based metabolome analysis of wild type and Rd1 retina and vitreous/lens. We show that eye opening is accompanied by changes in the concentration of selected metabolites in the retina and by alterations in the vitreous/lens composition only in the retinal degeneration context. As such, we identify NAcetylaspartate as a potential novel vitreous/lens marker reflecting progressive retinal degeneration. Thus, our data can help elucidating mechanisms underlying key events in retinal physiology and reveal changes occurring in pathology, while highlighting the importance of the vitreous/lens in the characterization of retinal diseases.
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Affiliation(s)
- Elisa Murenu
- Department of Ophthalmology, Ludwig-Maximilians-Universität München, Mathildenstraße 8, 80336 Munich, Germany;
- Department of Pharmacy, Ludwig-Maximilians Universität München, Butenandtstr. 7, 81377 Munich, Germany;
| | - Sarantos Kostidis
- Leiden University Medical Center, Center for Proteomics & Metabolomics, P.O. Box 9600, 2300 RC Leiden, The Netherlands; (S.K.); (M.G.)
| | - Shibojyoti Lahiri
- Biomedical Center Munich-Molecular Biology, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany; (S.L.); (A.I.)
| | - Anna S. Geserich
- Department of Pharmacy, Ludwig-Maximilians Universität München, Butenandtstr. 7, 81377 Munich, Germany;
| | - Axel Imhof
- Biomedical Center Munich-Molecular Biology, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany; (S.L.); (A.I.)
| | - Martin Giera
- Leiden University Medical Center, Center for Proteomics & Metabolomics, P.O. Box 9600, 2300 RC Leiden, The Netherlands; (S.K.); (M.G.)
| | - Stylianos Michalakis
- Department of Ophthalmology, Ludwig-Maximilians-Universität München, Mathildenstraße 8, 80336 Munich, Germany;
- Department of Pharmacy, Ludwig-Maximilians Universität München, Butenandtstr. 7, 81377 Munich, Germany;
- Correspondence: ; Tel.: +49-89-2180-77325
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25
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Conart JB, Blot G, Augustin S, Millet-Puel G, Roubeix C, Beguier F, Charles-Messance H, Touhami S, Sahel JA, Berrod JP, Léveillard T, Guillonneau X, Delarasse C, Sennlaub F. Insulin inhibits inflammation-induced cone death in retinal detachment. J Neuroinflammation 2020; 17:358. [PMID: 33243251 PMCID: PMC7694924 DOI: 10.1186/s12974-020-02039-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 11/17/2020] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Rhegmatogenous retinal detachment (RD) involving the macula is a major cause of visual impairment despite high surgical success rate, mainly because of cone death. RD causes the infiltration of activated immune cells, but it is not clear whether and how infiltrating inflammatory cells contribute to cone cell loss. METHODS Vitreous samples from patients with RD and from control patients with macular hole were analyzed to characterize the inflammatory response to RD. A mouse model of RD and retinal explants culture were then used to explore the mechanisms leading to cone death. RESULTS Analysis of vitreous samples confirms that RD induces a marked inflammatory response with increased cytokine and chemokine expression in humans, which is closely mimicked by experimental murine RD. In this model, we corroborate that myeloid cells and T-lymphocytes contribute to cone loss, as the inhibition of their accumulation by Thrombospondin 1 (TSP1) increased cone survival. Using monocyte/retinal co-cultures and TSP1 treatment in RD, we demonstrate that immune cell infiltration downregulates rod-derived cone viability factor (RdCVF), which physiologically regulates glucose uptake in cones. Insulin and the insulin sensitizers rosiglitazone and metformin prevent in part the RD-induced cone loss in vivo, despite the persistence of inflammation CONCLUSION: Our results describe a new mechanism by which inflammation induces cone death in RD, likely through cone starvation due to the downregulation of RdCVF that could be reversed by insulin. Therapeutic inhibition of inflammation and stimulation of glucose availability in cones by insulin signaling might prevent RD-associated cone death until the RD can be surgically repaired and improve visual outcome after RD. TRIAL REGISTRATION ClinicalTrials.gov NCT03318588.
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Affiliation(s)
- Jean-Baptiste Conart
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France.,Département d'Ophtalmologie, CHRU Nancy, Allée du Morvan, Vandoeuvre-lès-Nancy, France
| | - Guillaume Blot
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France
| | - Sébastien Augustin
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France
| | - Géraldine Millet-Puel
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France
| | - Christophe Roubeix
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France
| | - Fanny Beguier
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France
| | - Hugo Charles-Messance
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France
| | - Sara Touhami
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France
| | - José-Alain Sahel
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France
| | - Jean-Paul Berrod
- Département d'Ophtalmologie, CHRU Nancy, Allée du Morvan, Vandoeuvre-lès-Nancy, France
| | - Thierry Léveillard
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France
| | - Xavier Guillonneau
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France.
| | - Cécile Delarasse
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France.
| | - Florian Sennlaub
- Institut de la Vision, INSERM, UMR_S 968, CNRS, Sorbonne Université, 17 rue Moreau, F-75012, Paris, France.
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26
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Haydinger CD, Kittipassorn T, Peet DJ. Power to see-Drivers of aerobic glycolysis in the mammalian retina: A review. Clin Exp Ophthalmol 2020; 48:1057-1071. [PMID: 32710505 DOI: 10.1111/ceo.13833] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 07/03/2020] [Accepted: 07/20/2020] [Indexed: 12/17/2022]
Abstract
The mammalian retina converts most glucose to lactate rather than catabolizing it completely to carbon dioxide via oxidative phosphorylation, despite the availability of oxygen. This unusual metabolism is known as aerobic glycolysis or the Warburg effect. Molecules and pathways that drive aerobic glycolysis have been identified and thoroughly studied in the context of cancer but remain relatively poorly understood in the retina. Here, we review recent research on the molecular mechanisms that underly aerobic glycolysis in the retina, focusing on key glycolytic enzymes including hexokinase 2 (HK2), pyruvate kinase M2 (PKM2) and lactate dehydrogenase A (LDHA). We also discuss the potential involvement of cell signalling and transcriptional pathways including phosphoinositide 3-kinase (PI3K) signalling, fibroblast growth factor receptor (FGFR) signalling, and hypoxia-inducible factor 1 (HIF-1), which have been implicated in driving aerobic glycolysis in the context of cancer.
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Affiliation(s)
- Cameron D Haydinger
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Thaksaon Kittipassorn
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia.,Department of Physiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Mahidol, Thailand
| | - Daniel J Peet
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
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27
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Retinal energy metabolism in health and glaucoma. Prog Retin Eye Res 2020; 81:100881. [PMID: 32712136 DOI: 10.1016/j.preteyeres.2020.100881] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 06/25/2020] [Accepted: 06/28/2020] [Indexed: 01/17/2023]
Abstract
Energy metabolism refers to the processes by which life transfers energy to do cellular work. The retina's relatively large energy demands make it vulnerable to energy insufficiency. In addition, evolutionary pressures to optimize human vision have been traded against retinal ganglion cell bioenergetic fragility. Details of the metabolic profiles of the different retinal cells remain poorly understood and are challenging to resolve. Detailed immunohistochemical mapping of the energy pathway enzymes and substrate transporters has provided some insights and highlighted interspecies differences. The different spatial metabolic patterns between the vascular and avascular retinas can account for some inconsistent data in the literature. There is a consilience of evidence that at least some individuals with glaucoma have impaired RGC energy metabolism, either due to impaired nutrient supply or intrinsic metabolic perturbations. Bioenergetic-based therapy for glaucoma has a compelling pathophysiological foundation and is supported by recent successes in animal models. Recent demonstrations of visual and electrophysiological neurorecovery in humans with glaucoma is highly encouraging and motivates longer duration trials investigating bioenergetic neuroprotection.
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28
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Metabolite therapy guided by liquid biopsy proteomics delays retinal neurodegeneration. EBioMedicine 2020; 52:102636. [PMID: 32028070 PMCID: PMC7005447 DOI: 10.1016/j.ebiom.2020.102636] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/26/2019] [Accepted: 01/09/2020] [Indexed: 02/06/2023] Open
Abstract
Background Neurodegenerative diseases are incurable disorders caused by progressive neuronal cell death. Retinitis pigmentosa (RP) is a blinding neurodegenerative disease that results in photoreceptor death and progresses to the loss of the entire retinal network. We previously found that proteomic analysis of the adjacent vitreous served as way to indirectly biopsy the retina and identify changes in the retinal proteome. Methods We analyzed protein expression in liquid vitreous biopsies from autosomal recessive (ar)RP patients with PDE6A mutations and arRP mice with Pde6ɑ mutations. Proteomic analysis of retina and vitreous samples identified molecular pathways affected at the onset of photoreceptor death. Based on affected molecular pathways, arRP mice were treated with a ketogenic diet or metabolites involved in fatty-acid synthesis, oxidative phosphorylation, and the tricarboxylic acid (TCA) cycle. Findings Dietary supplementation of a single metabolite, ɑ-ketoglutarate, increased docosahexaeonic acid levels, provided neuroprotection, and enhanced visual function in arRP mice. A ketogenic diet delayed photoreceptor cell loss, while vitamin B supplementation had a limited effect. Finally, desorption electrospray ionization mass spectrometry imaging (DESI-MSI) on ɑ-ketoglutarate-treated mice revealed restoration of metabolites that correlated with our proteomic findings: uridine, dihydrouridine, and thymidine (pyrimidine and purine metabolism), glutamine and glutamate (glutamine/glutamate conversion), and succinic and aconitic acid (TCA cycle). Interpretation This study demonstrates that replenishing TCA cycle metabolites via oral supplementation prolongs retinal function and provides a neuroprotective effect on the photoreceptor cells and inner retinal network. Funding NIH grants [R01EY026682, R01EY024665, R01EY025225, R01EY024698, R21AG050437, P30EY026877, 5P30EY019007, R01EY018213, F30EYE027986, T32GM007337, 5P30CA013696], NSF grant CHE-1734082.
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29
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Petit L, Ma S, Cipi J, Cheng SY, Zieger M, Hay N, Punzo C. Aerobic Glycolysis Is Essential for Normal Rod Function and Controls Secondary Cone Death in Retinitis Pigmentosa. Cell Rep 2019; 23:2629-2642. [PMID: 29847794 PMCID: PMC5997286 DOI: 10.1016/j.celrep.2018.04.111] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 03/22/2018] [Accepted: 04/25/2018] [Indexed: 02/06/2023] Open
Abstract
Aerobic glycolysis accounts for ~80%–90% of glucose used by adult photoreceptors (PRs); yet, the importance of aerobic glycolysis for PR function or survival remains unclear. Here, we further established the role of aerobic glycolysis in murine rod and cone PRs. We show that loss of hexokinase-2 (HK2), a key aerobic glycolysis enzyme, does not affect PR survival or structure but is required for normal rod function. Rods with HK2 loss increase their mitochondrial number, suggesting an adaptation to the inhibition of aerobic glycolysis. In contrast, cones adapt without increased mitochondrial number but require HK2 to adapt to metabolic stress conditions such as those encountered in retinitis pigmentosa, where the loss of rods causes a nutrient shortage in cones. The data support a model where aerobic glycolysis in PRs is not a necessity but rather a metabolic choice that maximizes PR function and adaptability to nutrient stress conditions.
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Affiliation(s)
- Lolita Petit
- Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA, USA
| | - Shan Ma
- Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA, USA
| | - Joris Cipi
- Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA, USA
| | - Shun-Yun Cheng
- Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA, USA
| | - Marina Zieger
- Division of Pulmonary Medicine, Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
| | - Nissim Hay
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Claudio Punzo
- Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA, USA.
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30
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Blond F, Léveillard T. Functional Genomics of the Retina to Elucidate its Construction and Deconstruction. Int J Mol Sci 2019; 20:E4922. [PMID: 31590277 PMCID: PMC6801968 DOI: 10.3390/ijms20194922] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 10/01/2019] [Indexed: 12/20/2022] Open
Abstract
The retina is the light sensitive part of the eye and nervous tissue that have been used extensively to characterize the function of the central nervous system. The retina has a central position both in fundamental biology and in the physiopathology of neurodegenerative diseases. We address the contribution of functional genomics to the understanding of retinal biology by reviewing key events in their historical perspective as an introduction to major findings that were obtained through the study of the retina using genomics, transcriptomics and proteomics. We illustrate our purpose by showing that most of the genes of interest for retinal development and those involved in inherited retinal degenerations have a restricted expression to the retina and most particularly to photoreceptors cells. We show that the exponential growth of data generated by functional genomics is a future challenge not only in terms of storage but also in terms of accessibility to the scientific community of retinal biologists in the future. Finally, we emphasize on novel perspectives that emerge from the development of redox-proteomics, the new frontier in retinal biology.
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Affiliation(s)
- Frédéric Blond
- Department of Genetics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
| | - Thierry Léveillard
- Department of Genetics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
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31
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Determination of Mitochondrial Oxygen Consumption in the Retina Ex Vivo: Applications for Retinal Disease. Methods Mol Biol 2019; 1753:167-177. [PMID: 29564788 DOI: 10.1007/978-1-4939-7720-8_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Mitochondrial dysfunction, and consequently altered aerobic energy metabolism, is associated with numerous retinal diseases, including photoreceptor degeneration and diabetic retinopathy. Here, we describe a detailed protocol to directly measure oxygen consumption in the intact retina ex vivo using microplate-based fluorescence technology. We have used this method to assess preferred energy substrate for retinal tissue and suggested its application for investigating mechanisms of retinal disease.
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32
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A Rise in ATP, ROS, and Mitochondrial Content upon Glucose Withdrawal Correlates with a Dysregulated Mitochondria Turnover Mediated by the Activation of the Protein Deacetylase SIRT1. Cells 2018; 8:cells8010011. [PMID: 30591661 PMCID: PMC6356350 DOI: 10.3390/cells8010011] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 11/17/2022] Open
Abstract
Glucose withdrawal has been used as a model for the study of homeostatic defense mechanisms, especially for how cells cope with a shortage of nutrient supply by enhancing catabolism. However, detailed cellular responses to glucose withdrawal have been poorly studied, and are controversial. In this study, we determined how glucose withdrawal affects mitochondrial activity, and the quantity and the role of SIRT1 in these changes. The results of our study indicate a substantial increase in ATP production from mitochondria, through an elevation of mitochondrial biogenesis, mediated by SIRT1 activation that is driven by increased NAD⁺/NADH ratio. Moreover, mitochondria persisted in the cells as elongated forms, and apparently evaded mitophagic removal. This led to a steady increase in mitochondria content and the reactive oxygen species (ROS) generated from them, indicating failure in ATP and ROS homeostasis, due to a misbalance in SIRT1-mediated mitochondria turnover in conditions of glucose withdrawal. Our results suggest that SIRT1 activation alone cannot properly manage energy homeostasis under certain metabolic crisis conditions.
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She X, Lu X, Li T, Sun J, Liang J, Zhai Y, Yang S, Gu Q, Wei F, Zhu H, Wang F, Luo X, Sun X. Inhibition of Mitochondrial Fission Preserves Photoreceptors after Retinal Detachment. THE AMERICAN JOURNAL OF PATHOLOGY 2018; 188:1713-1722. [PMID: 29684364 DOI: 10.1016/j.ajpath.2018.03.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 02/23/2018] [Accepted: 03/26/2018] [Indexed: 01/13/2023]
Abstract
Photoreceptor degeneration is a leading cause of visual impairment worldwide. Separation of neurosensory retina from the underlying retinal pigment epithelium is a prominent feature preceding photoreceptor degeneration in a variety of retinal diseases. Although ophthalmic surgical procedures have been well developed to restore retinal structures, postoperative patients usually experience progressive photoreceptor degeneration and irreversible vision loss that is incurable at present. Previous studies point to a critical role of mitochondria-mediated apoptotic pathway in photoreceptor degeneration, but the upstream triggers remain largely unexplored. In this study, we show that after experimental retinal detachment induction, photoreceptors activate dynamin-related protein 1 (Drp1)-dependent mitochondrial fission pathway and subsequent apoptotic cascades. Mechanistically, endogenous reactive oxygen species (ROS) are necessary for Drp1 activation in vivo, and exogenous ROS insult is sufficient to activate Drp1-dependent mitochondrial fission in cultured photoreceptors. Accordingly, inhibition of Drp1 activity effectively preserves mitochondrial integrity and rescues photoreceptors. Collectively, our data delineate an ROS-Drp1-mitochondria axis that promotes photoreceptor degeneration in retinal diseased models.
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Affiliation(s)
- Xiangjun She
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai
| | - Xinmin Lu
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai
| | - Tong Li
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai
| | - Junran Sun
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai
| | - Jian Liang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai; Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai
| | - Yuanqi Zhai
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai; Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai
| | - Shiqi Yang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai
| | - Qing Gu
- Shanghai Key Laboratory of Fundus Diseases, Shanghai, People's Republic of China
| | - Fang Wei
- Shanghai Key Laboratory of Fundus Diseases, Shanghai, People's Republic of China
| | - Hong Zhu
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai; Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai
| | - Fenghua Wang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai; Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai
| | - Xueting Luo
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai; Shanghai Key Laboratory of Fundus Diseases, Shanghai, People's Republic of China.
| | - Xiaodong Sun
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai; Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai; Shanghai Key Laboratory of Fundus Diseases, Shanghai, People's Republic of China.
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34
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Santos FM, Gaspar LM, Ciordia S, Rocha AS, Castro E Sousa JP, Paradela A, Passarinha LA, Tomaz CT. iTRAQ Quantitative Proteomic Analysis of Vitreous from Patients with Retinal Detachment. Int J Mol Sci 2018; 19:ijms19041157. [PMID: 29641463 PMCID: PMC5979392 DOI: 10.3390/ijms19041157] [Citation(s) in RCA: 12] [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: 02/08/2018] [Revised: 04/07/2018] [Accepted: 04/08/2018] [Indexed: 12/15/2022] Open
Abstract
Rhegmatogenous retinal detachment (RRD) is a potentially blinding condition characterized by a physical separation between neurosensory retina and retinal pigment epithelium. Quantitative proteomics can help to understand the changes that occur at the cellular level during RRD, providing additional information about the molecular mechanisms underlying its pathogenesis. In the present study, iTRAQ labeling was combined with two-dimensional LC-ESI-MS/MS to find expression changes in the proteome of vitreous from patients with RRD when compared to control samples. A total of 150 proteins were found differentially expressed in the vitreous of patients with RRD, including 96 overexpressed and 54 underexpressed. Several overexpressed proteins, several such as glycolytic enzymes (fructose-bisphosphate aldolase A, gamma-enolase, and phosphoglycerate kinase 1), glucose transporters (GLUT-1), growth factors (metalloproteinase inhibitor 1), and serine protease inhibitors (plasminogen activator inhibitor 1) are regulated by HIF-1, which suggests that HIF-1 signaling pathway can be triggered in response to RRD. Also, the accumulation of photoreceptor proteins, including phosducin, rhodopsin, and s-arrestin, and vimentin in vitreous may indicate that photoreceptor degeneration occurs in RRD. Also, the accumulation of photoreceptor proteins, including phosducin, rhodopsin, and s-arrestin, and vimentin in vitreous may indicate that photoreceptor degeneration occurs in RRD. Nevertheless, the differentially expressed proteins found in this study suggest that different mechanisms are activated after RRD to promote the survival of retinal cells through complex cellular responses.
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Affiliation(s)
- Fátima Milhano Santos
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal.
- Chemistry Department, Faculty of Sciences, University of Beira Interior, 6201-001 Covilhã, Portugal.
- Laboratory of Pharmacology and Toxicology-UBIMedical, University of Beira Interior, 6200-284 Covilhã, Portugal.
| | - Leonor Mesquita Gaspar
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal.
- Chemistry Department, Faculty of Sciences, University of Beira Interior, 6201-001 Covilhã, Portugal.
| | - Sergio Ciordia
- Unidad de Proteomica, Centro Nacional de Biotecnología, CSIC, Calle Darwin 3, Campus de Cantoblanco, 28049 Madrid, Spain.
| | - Ana Sílvia Rocha
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal.
- Chemistry Department, Faculty of Sciences, University of Beira Interior, 6201-001 Covilhã, Portugal.
| | - João Paulo Castro E Sousa
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal.
- Hospital Center Leiria-Pombal, 3100-462 Pombal, Portugal.
| | - Alberto Paradela
- Unidad de Proteomica, Centro Nacional de Biotecnología, CSIC, Calle Darwin 3, Campus de Cantoblanco, 28049 Madrid, Spain.
| | - Luís António Passarinha
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal.
- Laboratory of Pharmacology and Toxicology-UBIMedical, University of Beira Interior, 6200-284 Covilhã, Portugal.
| | - Cândida Teixeira Tomaz
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal.
- Chemistry Department, Faculty of Sciences, University of Beira Interior, 6201-001 Covilhã, Portugal.
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35
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Wubben TJ, Pawar M, Smith A, Toolan K, Hager H, Besirli CG. Photoreceptor metabolic reprogramming provides survival advantage in acute stress while causing chronic degeneration. Sci Rep 2017; 7:17863. [PMID: 29259242 PMCID: PMC5736549 DOI: 10.1038/s41598-017-18098-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 12/05/2017] [Indexed: 11/16/2022] Open
Abstract
Photoreceptor death is the root cause of vision loss in many retinal disorders, and there is an unmet need for neuroprotective modalities to improve photoreceptor survival. The biosynthetic requirement of photoreceptors is among the highest in the body, and to meet this demand, photoreceptors maintain their ability to perform aerobic glycolysis. This highly regulated form of glycolysis allows cells to efficiently budget their metabolic needs and may be a critical link between photoreceptor function and survival. Pyruvate kinase muscle isozyme 2 (PKM2) is a key regulator of aerobic glycolysis. In the present study, we characterized the effect of PKM2 deletion on baseline functioning and survival of photoreceptors over time by utilizing a photoreceptor-specific, PKM2 knockout mouse model. We found that upon PKM2 deletion, PKM1 is upregulated in the outer retina and there is increased expression of genes involved in glucose metabolism, which led to chronic degenerative changes in the outer retina of these mice. We also discovered that this metabolic reprogramming provided a survival advantage to photoreceptors in an experimental model of retinal detachment. This study strongly supports the hypothesis that reprogramming metabolism may be a novel therapeutic strategy for photoreceptor neuroprotection during acute stress.
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Affiliation(s)
- Thomas J Wubben
- University of Michigan, Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, Ann Arbor, Michigan, USA
| | - Mercy Pawar
- University of Michigan, Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, Ann Arbor, Michigan, USA
| | - Andrew Smith
- University of Michigan, Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, Ann Arbor, Michigan, USA
| | - Kevin Toolan
- University of Michigan, Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, Ann Arbor, Michigan, USA
| | - Heather Hager
- University of Michigan, Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, Ann Arbor, Michigan, USA
| | - Cagri G Besirli
- University of Michigan, Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, Ann Arbor, Michigan, USA.
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36
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Luan Y, Ou J, Kunze VP, Qiao F, Wang Y, Wei L, Li W, Xie Z. Integrated transcriptomic and metabolomic analysis reveals adaptive changes of hibernating retinas. J Cell Physiol 2017; 233:1434-1445. [PMID: 28542832 DOI: 10.1002/jcp.26030] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/24/2017] [Indexed: 12/24/2022]
Abstract
Hibernation is a seasonally adaptive strategy that allows hibernators to live through extremely cold conditions. Despite the profound reduction of blood flow to the retinas, hibernation causes no lasting retinal injury. Instead, hibernators show an increased tolerance to ischemic insults during the hibernation period. To understand the molecular changes of the retinas in response to hibernation, we applied an integrative transcriptome and metabolome analysis to explore changes in gene expression and metabolites of 13-lined ground squirrel retinas during hibernation. Metabolomic analysis showed a global decrease of ATP synthesis in hibernating retinas. Decreased glucose and galactose, increased beta-oxidation of carnitine and decreased storage of some amino acids in hibernating retinas indicated a shift of fuel use from carbohydrates to lipids and alternative usage of amino acids. Transcriptomic analysis revealed that the down-regulated genes were enriched in DNA-templated transcription and immune-related functions, while the up-regulated genes were enriched in mitochondrial inner membrane and DNA packaging-related functions. We further showed that a subset of genes underwent active alternative splicing events in response to hibernation. Finally, integrative analysis of the transcriptome and metabolome confirmed the shift of fuel use in the hibernating retina by the regulation of catabolism of amino acids and lipids. Through transcriptomic and metabolomic data, our analysis revealed the altered state of mitochondrial oxidative phosphorylation and the shift of energy source in the hibernating retina, advancing our understanding of the molecular mechanisms employed by hibernators. The data will also serve as a useful resource for the ocular and hibernation research communities.
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Affiliation(s)
- Yizhao Luan
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.,School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jingxing Ou
- Retinal Neurobiology Section, National Eye Institute, Bethesda, Maryland
| | - Vincent P Kunze
- Retinal Neurobiology Section, National Eye Institute, Bethesda, Maryland
| | - Fengyu Qiao
- Retinal Neurobiology Section, National Eye Institute, Bethesda, Maryland
| | - Yan Wang
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Lai Wei
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Wei Li
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.,Retinal Neurobiology Section, National Eye Institute, Bethesda, Maryland
| | - Zhi Xie
- State Key Laboratory of Ophthalmology, Guangdong Provincial Key Lab of Ophthalmology, Visual Science, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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Chinchore Y, Begaj T, Wu D, Drokhlyansky E, Cepko CL. Glycolytic reliance promotes anabolism in photoreceptors. eLife 2017; 6. [PMID: 28598329 PMCID: PMC5499945 DOI: 10.7554/elife.25946] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 06/01/2017] [Indexed: 12/18/2022] Open
Abstract
Vertebrate photoreceptors are among the most metabolically active cells, exhibiting a high rate of ATP consumption. This is coupled with a high anabolic demand, necessitated by the diurnal turnover of a specialized membrane-rich organelle, the outer segment, which is the primary site of phototransduction. How photoreceptors balance their catabolic and anabolic demands is poorly understood. Here, we show that rod photoreceptors in mice rely on glycolysis for their outer segment biogenesis. Genetic perturbations targeting allostery or key regulatory nodes in the glycolytic pathway impacted the size of the outer segments. Fibroblast growth factor signaling was found to regulate glycolysis, with antagonism of this pathway resulting in anabolic deficits. These data demonstrate the cell autonomous role of the glycolytic pathway in outer segment maintenance and provide evidence that aerobic glycolysis is part of a metabolic program that supports the biosynthetic needs of a normal neuronal cell type. DOI:http://dx.doi.org/10.7554/eLife.25946.001 Living cells need building materials and energy to grow and carry out their activities. Most cells in the body use sugars like glucose for these purposes. In a process known as glycolysis, cells break down glucose into molecules that are eventually converted to carbon dioxide and water to form the chemical ATP – the cellular currency for energy. Developing cells that have not yet fully specialized, and rapidly dividing cells, like cancer cells, consume large amounts of glucose via aerobic glycolysis (also known as the Warburg effect) as they require high levels of energy and building materials. As cells become more specialized and divide less often, they have a reduced need for building blocks, and adjust their consumption and breakdown of glucose accordingly. One exception is the photoreceptor cells, found in the light-sensitive part of our eyes. Although these specialized cells do not divide, they still need a lot of energy and building blocks to constantly renew their light-sensing and processing structures, and to capture and convert the information from the environment into signals. Previous research has shown that the eye also uses the Warburg effect. However, until now, it was not known whether the photoreceptors or other cells in the eye carry out this form of glycolysis. Using genetic tools, Chinchore et al. analysed how the photoreceptor cells in mice used glucose. The experiments demonstrated that the photoreceptors do indeed carry out the Warburg effect. Chinchore et al. further discovered that the Warburg effect is regulated by the same key enzymes and signalling molecules that cancer cells use. This indicates that specialized cells like photoreceptors might choose to retain certain metabolic features of their precursor cells, if they need to. These findings provide new insight into how photoreceptors use glucose. The next step will be to understand how aerobic glycolysis is regulated in healthy eyes as well as in eyes that are affected by degenerating diseases, which may ultimately lead to new ways of treating blindness. DOI:http://dx.doi.org/10.7554/eLife.25946.002
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Affiliation(s)
- Yashodhan Chinchore
- Departments of Genetics and Ophthalmology, Harvard Medical School, Boston, United States
| | - Tedi Begaj
- Departments of Genetics and Ophthalmology, Harvard Medical School, Boston, United States
| | - David Wu
- Departments of Genetics and Ophthalmology, Harvard Medical School, Boston, United States
| | - Eugene Drokhlyansky
- Departments of Genetics and Ophthalmology, Harvard Medical School, Boston, United States
| | - Constance L Cepko
- Departments of Genetics and Ophthalmology, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Harvard Medical School, Boston, United States
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Narayan DS, Chidlow G, Wood JP, Casson RJ. Glucose metabolism in mammalian photoreceptor inner and outer segments. Clin Exp Ophthalmol 2017; 45:730-741. [PMID: 28334493 DOI: 10.1111/ceo.12952] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 02/25/2017] [Accepted: 03/20/2017] [Indexed: 12/22/2022]
Abstract
Photoreceptors are the first-order neurons of the visual pathway, converting light into electrical signals. Rods and cones are the two main types of photoreceptors in the mammalian retina. Rods are specialized for sensitivity at the expense of resolution and are responsible for vision in dimly lit conditions. Cones are responsible for high acuity central vision and colour vision. Many human retinal diseases are characterized by a progressive loss of photoreceptors. Photoreceptors consist of four primary regions: outer segments, inner segments, cell bodies and synaptic terminals. Photoreceptors consume large amounts of energy, and therefore, energy metabolism may be a critical juncture that links photoreceptor function and survival. Cones require more energy than rods, and cone degeneration is the main cause of clinically significant vision loss in retinal diseases. Photoreceptor segments are capable of utilizing various energy substrates, including glucose, to meet their large energy demands. The pathways by which photoreceptor segments meet their energy demands remain incompletely understood. Improvements in the understanding of glucose metabolism in photoreceptor segments may provide insight into the reasons why photoreceptors degenerate due to energy failure. This may, in turn, assist in developing bio-energetic therapies aimed at protecting photoreceptors.
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Affiliation(s)
- Daniel S Narayan
- Ophthalmic Research Laboratories, Hanson Institute Centre for Neurological Diseases, Adelaide, South Austalia, Australia.,South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Austalia, Australia
| | - Glyn Chidlow
- Ophthalmic Research Laboratories, Hanson Institute Centre for Neurological Diseases, Adelaide, South Austalia, Australia.,South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Austalia, Australia
| | - John Pm Wood
- Ophthalmic Research Laboratories, Hanson Institute Centre for Neurological Diseases, Adelaide, South Austalia, Australia.,South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Austalia, Australia
| | - Robert J Casson
- Ophthalmic Research Laboratories, Hanson Institute Centre for Neurological Diseases, Adelaide, South Austalia, Australia.,South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Austalia, Australia
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Zhou Z, Vinberg F, Schottler F, Doggett TA, Kefalov VJ, Ferguson TA. Autophagy supports color vision. Autophagy 2016; 11:1821-32. [PMID: 26292183 DOI: 10.1080/15548627.2015.1084456] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cones comprise only a small portion of the photoreceptors in mammalian retinas. However, cones are vital for color vision and visual perception, and their loss severely diminishes the quality of life for patients with retinal degenerative diseases. Cones function in bright light and have higher demand for energy than rods; yet, the mechanisms that support the energy requirements of cones are poorly understood. One such pathway that potentially could sustain cones under basal and stress conditions is macroautophagy. We addressed the role of macroautophagy in cones by examining how the genetic block of this pathway affects the structural integrity, survival, and function of these neurons. We found that macroautophagy was not detectable in cones under normal conditions but was readily observed following 24 h of fasting. Consistent with this, starvation induced phosphorylation of AMPK specifically in cones indicating cellular starvation. Inhibiting macroautophagy in cones by deleting the essential macroautophagy gene Atg5 led to reduced cone function following starvation suggesting that cones are sensitive to systemic changes in nutrients and activate macroautophagy to maintain their function. ATG5-deficiency rendered cones susceptible to light-induced damage and caused accumulation of damaged mitochondria in the inner segments, shortening of the outer segments, and degeneration of all cone types, revealing the importance of mitophagy in supporting cone metabolic needs. Our results demonstrate that macroautophagy supports the function and long-term survival of cones providing for their unique metabolic requirements and resistance to stress. Targeting macroautophagy has the potential to preserve cone-mediated vision during retinal degenerative diseases.
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Affiliation(s)
- Zhenqing Zhou
- a Department of Ophthalmology and Visual Sciences, Washington University in St. Louis; School of Medicine ; St. Louis , MO USA
| | - Frans Vinberg
- a Department of Ophthalmology and Visual Sciences, Washington University in St. Louis; School of Medicine ; St. Louis , MO USA
| | - Frank Schottler
- a Department of Ophthalmology and Visual Sciences, Washington University in St. Louis; School of Medicine ; St. Louis , MO USA
| | - Teresa A Doggett
- a Department of Ophthalmology and Visual Sciences, Washington University in St. Louis; School of Medicine ; St. Louis , MO USA
| | - Vladimir J Kefalov
- a Department of Ophthalmology and Visual Sciences, Washington University in St. Louis; School of Medicine ; St. Louis , MO USA
| | - Thomas A Ferguson
- a Department of Ophthalmology and Visual Sciences, Washington University in St. Louis; School of Medicine ; St. Louis , MO USA
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Boya P, Esteban-Martínez L, Serrano-Puebla A, Gómez-Sintes R, Villarejo-Zori B. Autophagy in the eye: Development, degeneration, and aging. Prog Retin Eye Res 2016; 55:206-245. [PMID: 27566190 DOI: 10.1016/j.preteyeres.2016.08.001] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 08/15/2016] [Accepted: 08/18/2016] [Indexed: 02/06/2023]
Abstract
Autophagy is a catabolic pathway that promotes the degradation and recycling of cellular components. Proteins, lipids, and even whole organelles are engulfed in autophagosomes and delivered to the lysosome for elimination. In response to stress, autophagy mediates the degradation of cell components, which are recycled to generate the nutrients and building blocks required to sustain cellular homeostasis. Moreover, it plays an important role in cellular quality control, particularly in neurons, in which the total burden of altered proteins and damaged organelles cannot be reduced by redistribution to daughter cells through cell division. Research has only begun to examine the role of autophagy in the visual system. The retina, a light-sensitive tissue, detects and transmits electrical impulses through the optic nerve to the visual cortex in the brain. Both the retina and the eye are exposed to a variety of environmental insults and stressors, including genetic mutations and age-associated alterations that impair their function. Here, we review the main studies that have sought to explain autophagy's importance in visual function. We describe the role of autophagy in retinal development and cell differentiation, and discuss the implications of autophagy dysregulation both in physiological aging and in important diseases such as age-associated macular degeneration and glaucoma. We also address the putative role of autophagy in promoting photoreceptor survival and discuss how selective autophagy could provide alternative means of protecting retinal cells. The findings reviewed here underscore the important role of autophagy in maintaining proper retinal function and highlight novel therapeutic approaches for blindness and other diseases of the eye.
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Affiliation(s)
- Patricia Boya
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain.
| | - Lorena Esteban-Martínez
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Ana Serrano-Puebla
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Raquel Gómez-Sintes
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Beatriz Villarejo-Zori
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
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41
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Fan B, Li FQ, Zuo L, Li GY. mTOR inhibition attenuates glucose deprivation-induced death in photoreceptors via suppressing a mitochondria-dependent apoptotic pathway. Neurochem Int 2016; 99:178-186. [PMID: 27401903 DOI: 10.1016/j.neuint.2016.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 07/06/2016] [Accepted: 07/06/2016] [Indexed: 12/21/2022]
Abstract
Acute energy depletion contributes to ischemia-induced retinal neuronal injury, causing photoreceptor death and subsequent vision loss. The mTOR pathway is a crucial cellular signaling hub modulating RNA transcription, protein synthesis, and metabolic balance. Thus, we mimicked acute energy depletion in photoreceptor cells (661W cells) with glucose deprivation and investigated neuroprotective mechanisms of mTOR inhibition. We found that treatment with rapamycin, an mTOR-specific inhibitor, reduced intracellular ROS, maintained the mitochondrial membrane potential and restored mitochondrial dysfunction. In addition, inhibiting the mTOR signal suppressed DRP1 translocation to the mitochondria, pro-apoptotic mitochondrial protein release, and caspase 3 activation when glucose was deprived. Inhibition of mTOR offers significant neuroprotection against glucose deprivation-induced injury in 661W cells, chiefly via suppressing mitochondrial-dependent pathways. These observations may shed light on treating ischemia-related retinal diseases.
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Affiliation(s)
- Bin Fan
- Department of Ophthalmology, Second Hospital of Jilin University, ChangChun 130041, China
| | - Fu-Qaing Li
- Department of Ophthalmology, Second Hospital of Jilin University, ChangChun 130041, China
| | - Ling Zuo
- Department of Ophthalmology, Second Hospital of Jilin University, ChangChun 130041, China
| | - Guang-Yu Li
- Department of Ophthalmology, Second Hospital of Jilin University, ChangChun 130041, China.
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42
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Natoli R, Rutar M, Lu YZ, Chu-Tan JA, Chen Y, Saxena K, Madigan M, Valter K, Provis JM. The Role of Pyruvate in Protecting 661W Photoreceptor-Like Cells Against Light-Induced Cell Death. Curr Eye Res 2016; 41:1473-1481. [DOI: 10.3109/02713683.2016.1139725] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Riccardo Natoli
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
- ANU Medical School, The Australian National University, Canberra, Australia
| | - Matt Rutar
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Yen-Zhen Lu
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Joshua A. Chu-Tan
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Yuwei Chen
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Kartik Saxena
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Michele Madigan
- School of Optometry and Vision Sciences, University of New South Wales, Sydney, Australia
- The Save Sight Institute, University of Sydney, Sydney, Australia
| | - Krisztina Valter
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
- ANU Medical School, The Australian National University, Canberra, Australia
| | - Jan M. Provis
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
- ANU Medical School, The Australian National University, Canberra, Australia
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43
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Kooragayala K, Gotoh N, Cogliati T, Nellissery J, Kaden TR, French S, Balaban R, Li W, Covian R, Swaroop A. Quantification of Oxygen Consumption in Retina Ex Vivo Demonstrates Limited Reserve Capacity of Photoreceptor Mitochondria. Invest Ophthalmol Vis Sci 2016; 56:8428-36. [PMID: 26747773 DOI: 10.1167/iovs.15-17901] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Cell death in neurodegeneration occurs at the convergence of diverse metabolic pathways. In the retina, a common underlying mechanism involves mitochondrial dysfunction since photoreceptor homeostasis and survival are highly susceptible to altered aerobic energy metabolism. We sought to develop an assay to directly measure oxygen consumption in intact retina with the goal of identifying alterations in respiration during photoreceptor dysfunction and degeneration. METHODS Circular punches of freshly isolated mouse retina, adjacent to the optic nerve head, were used in the microplate-based Seahorse Extracellular Flux Analyzer to measure oxygen consumption. Tissue integrity was evaluated by propidium iodide staining and live imaging. Different substrates were tested for mitochondrial respiration. Basal and maximal respiration were expressed as oxygen consumption rate (OCR) and respectively measured in Ames' medium before and after the addition of mitochondrial uncoupler, BAM15. RESULTS We show that glucose is an essential substrate for retinal mitochondria. At baseline, mitochondria respiration in the intact wild-type retina was close to maximal, with limited reserve capacity. Similar OCR and limited mitochondrial reserve capacity was also observed in cone-only Nrl-/- retina. However, the retina of Pde6brd1/rd1, Cep290rd16/rd16 and Rpgrip1-/- mice, all with dysfunctional or no photoreceptors, had reduced OCR and higher mitochondrial reserve capacity. CONCLUSIONS We have optimized a method to directly measure oxygen consumption in acutely isolated, ex vivo mouse retina and demonstrate that photoreceptors have low mitochondrial reserve capacity. Our data provide a plausible explanation for the high vulnerability of photoreceptors to altered energy homeostasis caused by mutations or metabolic challenges.
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Affiliation(s)
- Keshav Kooragayala
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Norimoto Gotoh
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Tiziana Cogliati
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Jacob Nellissery
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Talia R Kaden
- Retinal Neurobiology Section, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Stephanie French
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Robert Balaban
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Wei Li
- Retinal Neurobiology Section, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Raul Covian
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Anand Swaroop
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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Wong BH, Chan JP, Cazenave-Gassiot A, Poh RW, Foo JC, Galam DLA, Ghosh S, Nguyen LN, Barathi VA, Yeo SW, Luu CD, Wenk MR, Silver DL. Mfsd2a Is a Transporter for the Essential ω-3 Fatty Acid Docosahexaenoic Acid (DHA) in Eye and Is Important for Photoreceptor Cell Development. J Biol Chem 2016; 291:10501-14. [PMID: 27008858 DOI: 10.1074/jbc.m116.721340] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Indexed: 12/22/2022] Open
Abstract
Eye photoreceptor membrane discs in outer rod segments are highly enriched in the visual pigment rhodopsin and the ω-3 fatty acid docosahexaenoic acid (DHA). The eye acquires DHA from blood, but transporters for DHA uptake across the blood-retinal barrier or retinal pigment epithelium have not been identified. Mfsd2a is a newly described sodium-dependent lysophosphatidylcholine (LPC) symporter expressed at the blood-brain barrier that transports LPCs containing DHA and other long-chain fatty acids. LPC transport via Mfsd2a has been shown to be necessary for human brain growth. Here we demonstrate that Mfsd2a is highly expressed in retinal pigment epithelium in embryonic eye, before the development of photoreceptors, and is the primary site of Mfsd2a expression in the eye. Eyes from whole body Mfsd2a-deficient (KO) mice, but not endothelium-specific Mfsd2a-deficient mice, were DHA-deficient and had significantly reduced LPC/DHA transport in vivo Fluorescein angiography indicated normal blood-retinal barrier function. Histological and electron microscopic analysis indicated that Mfsd2a KO mice exhibited a specific reduction in outer rod segment length, disorganized outer rod segment discs, and mislocalization of and reduction in rhodopsin early in postnatal development without loss of photoreceptors. Minor photoreceptor cell loss occurred in adult Mfsd2a KO mice, but electroretinography indicated visual function was normal. The developing eyes of Mfsd2a KO mice had activated microglia and up-regulation of lipogenic and cholesterogenic genes, likely adaptations to loss of LPC transport. These findings identify LPC transport via Mfsd2a as an important pathway for DHA uptake in eye and for development of photoreceptor membrane discs.
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Affiliation(s)
- Bernice H Wong
- From the Signature Research Program in Cardiovascular and Metabolic Disorders
| | - Jia Pei Chan
- From the Signature Research Program in Cardiovascular and Metabolic Disorders
| | - Amaury Cazenave-Gassiot
- the Department of Biochemistry, National University of Singapore, 8 Medical Drive, Block MD 7, Singapore 117597, Singapore
| | - Rebecca W Poh
- the Carl Zeiss Pte. Ltd., Microscopy Business Group, Singapore, 50 Kaki Bukit Place, 05-01, Singapore 415926, Singapore
| | - Juat Chin Foo
- the Department of Biochemistry, National University of Singapore, 8 Medical Drive, Block MD 7, Singapore 117597, Singapore
| | - Dwight L A Galam
- From the Signature Research Program in Cardiovascular and Metabolic Disorders
| | - Sujoy Ghosh
- From the Signature Research Program in Cardiovascular and Metabolic Disorders, Centre for Computational Biology, and
| | - Long N Nguyen
- the Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 5 Science Drive 2, Building MD4, Level 1-03A, Singapore 117545, Singapore
| | - Veluchamy A Barathi
- the Singapore Eye Research Institute, 11 Third Hospital Ave., Singapore 168751, Singapore, the Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Rd 119228, NUHS Tower Block, Level 11, Singapore 117597, Singapore, and ACP Ophthalmology, Duke-National University of Singapore Graduate Medical School, 8 College Road, Singapore 169857, Singapore
| | - Sia W Yeo
- the Singapore Eye Research Institute, 11 Third Hospital Ave., Singapore 168751, Singapore
| | - Chi D Luu
- the Singapore Eye Research Institute, 11 Third Hospital Ave., Singapore 168751, Singapore, the Centre for Eye Research Australia, Level 1, 32 Gisborne St., East Melbourne, Victoria 3002, Australia
| | - Markus R Wenk
- the Department of Biochemistry, National University of Singapore, 8 Medical Drive, Block MD 7, Singapore 117597, Singapore
| | - David L Silver
- From the Signature Research Program in Cardiovascular and Metabolic Disorders,
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Kurihara T, Westenskow PD, Gantner ML, Usui Y, Schultz A, Bravo S, Aguilar E, Wittgrove C, Friedlander MS, Paris LP, Chew E, Siuzdak G, Friedlander M. Hypoxia-induced metabolic stress in retinal pigment epithelial cells is sufficient to induce photoreceptor degeneration. eLife 2016; 5. [PMID: 26978795 PMCID: PMC4848091 DOI: 10.7554/elife.14319] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 03/11/2016] [Indexed: 12/24/2022] Open
Abstract
Photoreceptors are the most numerous and metabolically demanding cells in the retina. Their primary nutrient source is the choriocapillaris, and both the choriocapillaris and photoreceptors require trophic and functional support from retinal pigment epithelium (RPE) cells. Defects in RPE, photoreceptors, and the choriocapillaris are characteristic of age-related macular degeneration (AMD), a common vision-threatening disease. RPE dysfunction or death is a primary event in AMD, but the combination(s) of cellular stresses that affect the function and survival of RPE are incompletely understood. Here, using mouse models in which hypoxia can be genetically triggered in RPE, we show that hypoxia-induced metabolic stress alone leads to photoreceptor atrophy. Glucose and lipid metabolism are radically altered in hypoxic RPE cells; these changes impact nutrient availability for the sensory retina and promote progressive photoreceptor degeneration. Understanding the molecular pathways that control these responses may provide important clues about AMD pathogenesis and inform future therapies. DOI:http://dx.doi.org/10.7554/eLife.14319.001 Cells use a sugar called glucose as fuel to provide energy for many essential processes. The light-sensing cells in the eye, known as photoreceptors, need tremendous amounts of glucose, which they receive from the blood with the help of neighboring cells called retinal pigment epithelium (RPE) cells. Without a reliable supply of this sugar, the photoreceptors die and vision is lost. As we age, we are at greater risk of vision loss because RPE cells become less efficient at transporting glucose and our blood vessels shrink so that the photoreceptors may become starved of glucose. To prevent age-related vision loss, we need new strategies to keep blood vessels and RPE cells healthy. However, it was not clear exactly how RPE cells supply photoreceptors with glucose, and what happens when blood supplies are reduced. To address this question, Kurihara, Westenskow et al. used genetically modified mice to investigate how cells in the eye respond to starvation. The experiments show that when nutrients are scarce the RPE cells essentially panic, radically change their diet, and become greedy. That is to say that they double in size and begin burning fuel faster while also stockpiling extra sugar and fat for later use. In turn, the photoreceptors don’t get the energy they need and so they slowly stop working and die. Kurihara, Westenskow et al. also show that there is a rapid change in the way in which sugar and fat are processed in the eye during starvation. Learning how to prevent these changes in patients with age-related vision loss could protect their photoreceptors from starvation and death. The next step following on from this research is to design drugs to improve the supply of glucose and nutrients to the photoreceptors by repairing aging blood vessels and/or preventing RPE cells from stockpiling glucose for themselves. DOI:http://dx.doi.org/10.7554/eLife.14319.002
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Affiliation(s)
- Toshihide Kurihara
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States
| | - Peter D Westenskow
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States.,The Lowy Medical Research Institute, La Jolla, United States
| | - Marin L Gantner
- The Lowy Medical Research Institute, La Jolla, United States
| | - Yoshihiko Usui
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States
| | - Andrew Schultz
- Center for Metabolomics, The Scripps Research Institute, La Jolla, United States
| | - Stephen Bravo
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States
| | - Edith Aguilar
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States
| | - Carli Wittgrove
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States
| | - Mollie Sh Friedlander
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States
| | - Liliana P Paris
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States
| | - Emily Chew
- National Eye Institute, National Institutes of Health, Bethesda, United States
| | - Gary Siuzdak
- Center for Metabolomics, The Scripps Research Institute, La Jolla, United States
| | - Martin Friedlander
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States
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Lactate Transport and Receptor Actions in Retina: Potential Roles in Retinal Function and Disease. Neurochem Res 2015; 41:1229-36. [PMID: 26677077 DOI: 10.1007/s11064-015-1792-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 11/06/2015] [Accepted: 11/08/2015] [Indexed: 01/01/2023]
Abstract
In retina, like in brain, lactate equilibrates across cell membranes via monocarboxylate transporters and in the extracellular space by diffusion, forming a basis for the action of lactate as a transmitter of metabolic signals. In the present paper, we argue that the lactate receptor GPR81, also known as HCAR1, may contribute importantly to the control of retinal cell functions in health and disease. GPR81, a G-protein coupled receptor, is known to downregulate cAMP both in adipose and nervous tissue. The receptor also acts through other down-stream mechanisms to control functions, such as excitability, metabolism and inflammation. Recent publications predict effects of the lactate receptor on neurodegeneration. Neurodegenerative diseases in retina, where the retinal ganglion cells die, notably glaucoma and diabetic retinopathy, may be linked to disturbed lactate homeostasis. Pilot studies reveal high GPR81 mRNA in retina and indicate GPR81 localization in Müller cells and retinal ganglion cells. Moreover, monocarboxylate transporters are expressed in retinal cells. We envision that lactate receptors and transporters could be useful future targets of novel therapeutic strategies to protect neurons and prevent or counteract glaucoma as well as other retinal diseases.
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Du J, Rountree A, Cleghorn WM, Contreras L, Lindsay KJ, Sadilek M, Gu H, Djukovic D, Raftery D, Satrústegui J, Kanow M, Chan L, Tsang SH, Sweet IR, Hurley JB. Phototransduction Influences Metabolic Flux and Nucleotide Metabolism in Mouse Retina. J Biol Chem 2015; 291:4698-710. [PMID: 26677218 DOI: 10.1074/jbc.m115.698985] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Indexed: 01/20/2023] Open
Abstract
Production of energy in a cell must keep pace with demand. Photoreceptors use ATP to maintain ion gradients in darkness, whereas in light they use it to support phototransduction. Matching production with consumption can be accomplished by coupling production directly to consumption. Alternatively, production can be set by a signal that anticipates demand. In this report we investigate the hypothesis that signaling through phototransduction controls production of energy in mouse retinas. We found that respiration in mouse retinas is not coupled tightly to ATP consumption. By analyzing metabolic flux in mouse retinas, we also found that phototransduction slows metabolic flux through glycolysis and through intermediates of the citric acid cycle. We also evaluated the relative contributions of regulation of the activities of α-ketoglutarate dehydrogenase and the aspartate-glutamate carrier 1. In addition, a comprehensive analysis of the retinal metabolome showed that phototransduction also influences steady-state concentrations of 5'-GMP, ribose-5-phosphate, ketone bodies, and purines.
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Affiliation(s)
- Jianhai Du
- From the Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington 98109
| | | | | | - Laura Contreras
- Department of Molecular Biology, Centre for Molecular Biology Severo Ochoa, Universidad Autonoma de Madrid-Consejo Superior de Investigaciones Científicas, CIBER of Rare Diseases (CIBERER), and Health Research Institute Jimenez Diaz Foundation, Autonomous University of Madrid, 28049 Madrid, Spain
| | | | | | - Haiwei Gu
- Northwest Metabolomics Research Center, Department of Anesthesiology and Pain Medicine
| | - Danijel Djukovic
- Northwest Metabolomics Research Center, Department of Anesthesiology and Pain Medicine
| | - Dan Raftery
- Northwest Metabolomics Research Center, Department of Anesthesiology and Pain Medicine
| | - Jorgina Satrústegui
- Department of Molecular Biology, Centre for Molecular Biology Severo Ochoa, Universidad Autonoma de Madrid-Consejo Superior de Investigaciones Científicas, CIBER of Rare Diseases (CIBERER), and Health Research Institute Jimenez Diaz Foundation, Autonomous University of Madrid, 28049 Madrid, Spain
| | | | - Lawrence Chan
- Bernard and Shirlee Brown Glaucoma Laboratory and Barbara and Donald Jonas Stem Cell Laboratory, Department of Ophthalmology, Columbia University, New York, New York, and
| | - Stephen H Tsang
- Bernard and Shirlee Brown Glaucoma Laboratory and Barbara and Donald Jonas Stem Cell Laboratory, Department of Ophthalmology, Columbia University, New York, New York, and Department of Pathology and Cell Biology and Institute of Human Nutrition, Columbia University, New York, New York 10032
| | | | - James B Hurley
- From the Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington 98109,
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Du J, Linton JD, Hurley JB. Probing Metabolism in the Intact Retina Using Stable Isotope Tracers. Methods Enzymol 2015; 561:149-70. [PMID: 26358904 DOI: 10.1016/bs.mie.2015.04.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Vertebrate retinas have several characteristics that make them particularly interesting from a metabolic perspective. The retinas have a highly laminated structure, high energy demands, and they share several metabolic features with tumors, such as a strong Warburg effect and abundant pyruvate kinase M2 isoform expression. The energy demands of retinas are both qualitatively and quantitatively different in light and darkness and metabolic dysfunction could cause retinal degeneration. Stable isotope-based metabolic analysis with mass spectrometry is a powerful tool to trace the dynamic metabolic reactions and reveal novel metabolic pathways within cells and between cells in retina. Here, we describe methods to quantify retinal metabolism in intact retinas and discuss applications of these methods to the understanding of neuron-glia interaction, light and dark adaptation, and retinal degenerative diseases.
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Affiliation(s)
- Jianhai Du
- Departments of Biochemistry, University of Washington, Seattle, Washington, USA; Department of Ophthalmology, University of Washington, Seattle, Washington, USA
| | - Jonathan D Linton
- Departments of Biochemistry, University of Washington, Seattle, Washington, USA; Department of Ophthalmology, University of Washington, Seattle, Washington, USA
| | - James B Hurley
- Departments of Biochemistry, University of Washington, Seattle, Washington, USA; Department of Ophthalmology, University of Washington, Seattle, Washington, USA.
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Ma S, Venkatesh A, Langellotto F, Le YZ, Hall MN, Rüegg MA, Punzo C. Loss of mTOR signaling affects cone function, cone structure and expression of cone specific proteins without affecting cone survival. Exp Eye Res 2015; 135:1-13. [PMID: 25887293 DOI: 10.1016/j.exer.2015.04.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 04/01/2015] [Accepted: 04/09/2015] [Indexed: 10/23/2022]
Abstract
Cones are the primary photoreceptor (PR) cells responsible for vision in humans. They are metabolically highly active requiring phosphoinositide 3-kinase (PI3K) activity for long-term survival. One of the downstream targets of PI3K is the kinase mammalian target of rapamycin (mTOR), which is a key regulator of cell metabolism and growth, integrating nutrient availability and growth factor signals. Both PI3K and mTOR are part of the insulin/mTOR signaling pathway, however if mTOR is required for long-term PR survival remains unknown. This is of particular interest since deregulation of this pathway in diabetes results in reduced PR function before the onset of any clinical signs of diabetic retinopathy. mTOR is found in two distinct complexes (mTORC1 & mTORC2) that are characterized by their unique accessory proteins RAPTOR and RICTOR respectively. mTORC1 regulates mainly cell metabolism in response to nutrient availability and growth factor signals, while mTORC2 regulates pro-survival mechanisms in response to growth factors. Here we analyze the effect on cones of loss of mTORC1, mTORC2 and simultaneous loss of mTORC1 & mTORC2. Interestingly, neither loss of mTORC1 nor mTORC2 affects cone function or survival at one year of age. However, outer and inner segment morphology is affected upon loss of either complex. In contrast, concurrent loss of mTORC1 and mTORC2 leads to a reduction in cone function without affecting cone viability. The data indicates that PI3K mediated pro-survival signals diverge upstream of both mTOR complexes in cones, suggesting that they are independent of mTOR activity. Furthermore, the data may help explain why PR function is reduced in diabetes, which can lead to deregulation of both mTOR complexes simultaneously. Finally, although mTOR is a key regulator of cell metabolism, and PRs are metabolically highly active, the data suggests that the role of mTOR in regulating the metabolic transcriptome in healthy cones is minimal.
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Affiliation(s)
- Shan Ma
- Tianjin Medical University Eye Hospital, No. 251 Fu Kang Road, Nankai District, Tianjin 300384, PR China; Department of Ophthalmology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA.
| | - Aditya Venkatesh
- Department of Ophthalmology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA.
| | - Fernanda Langellotto
- Department of Ophthalmology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA.
| | - Yun Z Le
- Department of Medicine Endocrinology, University of Oklahoma Health Sciences Center, BSEB 302G, 941 S L Young Blvd., Oklahoma City 73104, USA.
| | - Michael N Hall
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
| | - Markus A Rüegg
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
| | - Claudio Punzo
- Department of Ophthalmology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA.
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50
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Ramachandran PS, Song JY, Bennett J. Exploiting metabolic and antioxidant pathways to maintain vision in blinding disease. J Clin Invest 2015; 125:1390-2. [PMID: 25798615 DOI: 10.1172/jci80821] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The use of gene therapy for blinding disease shows growing promise; however, due to an ever-expanding list of disease-causing genes and mutations, the identification of a generic gene-based treatment is urgently needed. In many forms of degenerative retinal disease, there may be a window of opportunity to preserve daylight vision, as the cone photoreceptors degenerate more slowly than do the rods. In this issue of the JCI, Venkatesh et al. and Xiong et al. exploit two different pathways to promote cone cell survival and preserve vision in murine retinal degeneration models. These studies provide hope for developing a universal reagent to treat many different blinding disorders.
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