51
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Das Y, Swinkels D, Kocherlakota S, Vinckier S, Vaz FM, Wever E, van Kampen AHC, Jun B, Do KV, Moons L, Bazan NG, Van Veldhoven PP, Baes M. Peroxisomal Multifunctional Protein 2 Deficiency Perturbs Lipid Homeostasis in the Retina and Causes Visual Dysfunction in Mice. Front Cell Dev Biol 2021; 9:632930. [PMID: 33604342 PMCID: PMC7884615 DOI: 10.3389/fcell.2021.632930] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/11/2021] [Indexed: 01/09/2023] Open
Abstract
Patients lacking multifunctional protein 2 (MFP2), the central enzyme of the peroxisomal β-oxidation pathway, develop retinopathy. This pathway is involved in the metabolism of very long chain (VLCFAs) and polyunsaturated (PUFAs) fatty acids, which are enriched in the photoreceptor outer segments (POS). The molecular mechanisms underlying the retinopathy remain, however, elusive. Here, we report that mice with MFP2 inactivation display decreased retinal function already at the age of 3 weeks, which is accompanied by a profound shortening of the photoreceptor outer and inner segments, but with preserved photoreceptor ultrastructure. Furthermore, MFP2 deficient retinas exhibit severe changes in gene expression with downregulation of genes involved in the phototransduction pathway and upregulation of inflammation related genes. Lipid profiling of the mutant retinas revealed a profound reduction of DHA-containing phospholipids. This was likely due to a hampered systemic supply and retinal traffic of this PUFA, although we cannot exclude that the local defect of peroxisomal β-oxidation contributes to this DHA decrease. Moreover, very long chain PUFAs were also reduced, with the exception of those containing ≥ 34 carbons that accumulated. The latter suggests that there is an uncontrollable elongation of retinal PUFAs. In conclusion, our data reveal that intact peroxisomal β-oxidation is indispensable for retinal integrity, most likely by maintaining PUFA homeostasis.
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Affiliation(s)
- Yannick Das
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Daniëlle Swinkels
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Sai Kocherlakota
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Stefan Vinckier
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven-VIB, Leuven, Belgium
| | - Frédéric M Vaz
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands.,Core Facility Metabolomics, Amsterdam University Medical Center (UMC), Amsterdam, Netherlands
| | - Eric Wever
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands.,Core Facility Metabolomics, Amsterdam University Medical Center (UMC), Amsterdam, Netherlands.,Bioinformatics Laboratory, Department of Epidemiology and Data Science, Amsterdam Public Health Research Institute, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Antoine H C van Kampen
- Bioinformatics Laboratory, Department of Epidemiology and Data Science, Amsterdam Public Health Research Institute, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands.,Biosystems Data Analysis, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
| | - Bokkyoo Jun
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Khanh V Do
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Lieve Moons
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Paul P Van Veldhoven
- Lipid Biochemistry and Protein Interactions (LIPIT), Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Myriam Baes
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
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52
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Bullock J, Polato F, Abu-Asab M, Bernardo-Colón A, Aflaki E, Agbaga MP, Becerra SP. Degradation of Photoreceptor Outer Segments by the Retinal Pigment Epithelium Requires Pigment Epithelium-Derived Factor Receptor (PEDF-R). Invest Ophthalmol Vis Sci 2021; 62:30. [PMID: 33605986 PMCID: PMC7900850 DOI: 10.1167/iovs.62.2.30] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 01/19/2021] [Indexed: 12/28/2022] Open
Abstract
Purpose To examine the contribution of pigment epithelium-derived factor receptor (PEDF-R) to the phagocytosis process. Previously, we identified PEDF-R, the protein encoded by the PNPLA2 gene, as a phospholipase A2 in the retinal pigment epithelium (RPE). During phagocytosis, RPE cells ingest abundant phospholipids and protein in the form of photoreceptor outer segment (POS) tips, which are then hydrolyzed. The role of PEDF-R in RPE phagocytosis is not known. Methods Mice in which PNPLA2 was conditionally knocked out (cKO) in the RPE were generated. Mouse RPE/choroid explants were cultured. Human ARPE-19 cells were transfected with siPNPLA2 silencing duplexes. POSs were isolated from bovine retinas. The phospholipase A2 inhibitor bromoenol lactone was used. Transmission electron microscopy, immunofluorescence, lipid labeling, pulse-chase experiments, western blots, and free fatty acid and β-hydroxybutyrate assays were performed. Results The RPE of the cKO mice accumulated lipids, as well as more abundant and larger rhodopsin particles, compared to littermate controls. Upon POS exposure, RPE explants from cKO mice released less β-hydroxybutyrate compared to controls. After POS ingestion during phagocytosis, rhodopsin degradation was stalled both in cells treated with bromoenol lactone and in PNPLA2-knocked-down cells relative to their corresponding controls. Phospholipase A2 inhibition lowered β-hydroxybutyrate release from phagocytic RPE cells. PNPLA2 knockdown also resulted in a decline in fatty acids and β-hydroxybutyrate release from phagocytic RPE cells. Conclusions PEDF-R downregulation delayed POS digestion during phagocytosis. The findings imply that the efficiency of RPE phagocytosis depends on PEDF-R, thus identifying a novel contribution of this protein to POS degradation in the RPE.
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Affiliation(s)
- Jeanee Bullock
- Section of Protein Structure and Function, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington DC, United States
| | - Federica Polato
- Section of Protein Structure and Function, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Mones Abu-Asab
- Section of Histopathology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Alexandra Bernardo-Colón
- Section of Protein Structure and Function, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Elma Aflaki
- Section of Protein Structure and Function, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Martin-Paul Agbaga
- Departments of Cell Biology and Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - S. Patricia Becerra
- Section of Protein Structure and Function, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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53
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Mitochondria: The Retina's Achilles' Heel in AMD. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1256:237-264. [PMID: 33848005 DOI: 10.1007/978-3-030-66014-7_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Strong experimental evidence from studies in human donor retinas and animal models supports the idea that the retinal pathology associated with age-related macular degeneration (AMD) involves mitochondrial dysfunction and consequent altered retinal metabolism. This chapter provides a brief overview of mitochondrial structure and function, summarizes evidence for mitochondrial defects in AMD, and highlights the potential ramifications of these defects on retinal health and function. Discussion of mitochondrial haplogroups and their association with AMD brings to light how mitochondrial genetics can influence disease outcome. As one of the most metabolically active tissues in the human body, there is strong evidence that disruption in key metabolic pathways contributes to AMD pathology. The section on retinal metabolism reviews cell-specific metabolic differences and how the metabolic interdependence of each retinal cell type creates a unique ecosystem that is disrupted in the diseased retina. The final discussion includes strategies for therapeutic interventions that target key mitochondrial pathways as a treatment for AMD.
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54
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Ryals RC, Huang SJ, Wafai D, Bernert C, Steele W, Six M, Bonthala S, Titus H, Yang P, Gillingham M, Pennesi ME. A Ketogenic & Low-Protein Diet Slows Retinal Degeneration in rd10 Mice. Transl Vis Sci Technol 2020; 9:18. [PMID: 33117609 PMCID: PMC7571290 DOI: 10.1167/tvst.9.11.18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 09/23/2020] [Indexed: 01/01/2023] Open
Abstract
Purpose Treatments that delay retinal cell death regardless of genetic causation are needed for inherited retinal degeneration (IRD) patients. The ketogenic diet is a high-fat, low-carbohydrate diet, used to treat epilepsy, and has beneficial effects for neurodegenerative diseases. This study aimed to determine whether the ketogenic diet could slow retinal degeneration. Methods Early weaned, rd10 and wild-type (WT) mice were placed on either standard chow, a ketogenic diet, or a ketogenic & low-protein diet. From postnatal day (PD) 23 to PD50, weight and blood β-hydroxybutyrate levels were recorded. Retinal thickness, retinal function, and visual performance were measured via optical coherence tomography, electroretinography (ERG), and optokinetic tracking (OKT). At PD40, serum albumin, rhodopsin protein, and phototransduction gene expression were measured. Results Both ketogenic diets elicited a systemic induction of ketosis. However, rd10 mice on the ketogenic & low-protein diet had significant increases in photoreceptor thickness, ERG amplitudes, and OKT thresholds, whereas rd10 mice on the ketogenic diet showed no photoreceptor preservation. In both rd10 and WT mice, the ketogenic & low-protein diet was associated with abnormal weight gain and decreases in serum albumin levels, 27% and 56%, respectively. In WT mice, the ketogenic & low-protein diet was also associated with an ∼20% to 30% reduction in ERG amplitudes. Conclusions The ketogenic & low-protein diet slowed retinal degeneration in a clinically relevant IRD model. In WT mice, the ketogenic & low-protein diet was associated with a decrease in phototransduction and serum albumin, which could serve as a protective mechanism in the rd10 model. Although ketosis was associated with protection, its role remains unclear. Translational Relevance Neuroprotective mechanisms associated with the ketogenic & low-protein diet have potential to slow retinal degeneration.
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Affiliation(s)
- Renee C Ryals
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Samuel J Huang
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Dahlia Wafai
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Claire Bernert
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - William Steele
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Makayla Six
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Shasank Bonthala
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Hope Titus
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Paul Yang
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Melanie Gillingham
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR, USA
| | - Mark E Pennesi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
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55
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Li B, Zhang T, Liu W, Wang Y, Xu R, Zeng S, Zhang R, Zhu S, Gillies MC, Zhu L, Du J. Metabolic Features of Mouse and Human Retinas: Rods versus Cones, Macula versus Periphery, Retina versus RPE. iScience 2020; 23:101672. [PMID: 33196018 PMCID: PMC7644940 DOI: 10.1016/j.isci.2020.101672] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/21/2020] [Accepted: 10/08/2020] [Indexed: 02/07/2023] Open
Abstract
Photoreceptors, especially cones, which are enriched in the human macula, have high energy demands, making them vulnerable to metabolic stress. Metabolic dysfunction of photoreceptors and their supporting retinal pigment epithelium (RPE) is an important underlying cause of degenerative retinal diseases. However, how cones and the macula support their exorbitant metabolic demand and communicate with RPE is unclear. By profiling metabolite uptake and release and analyzing metabolic genes, we have found cone-rich retinas and human macula share specific metabolic features with upregulated pathways in pyruvate metabolism, mitochondrial TCA cycle, and lipid synthesis. Human neural retina and RPE have distinct but complementary metabolic features. Retinal metabolism centers on NADH production and neurotransmitter biosynthesis. The retina needs aspartate to sustain its aerobic glycolysis and mitochondrial metabolism. RPE metabolism is directed toward NADPH production and biosynthesis of acetyl-rich metabolites, serine, and others. RPE consumes multiple nutrients, including proline, to produce metabolites for the retina.
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Affiliation(s)
- Bo Li
- Departments of Ophthalmology and Biochemistry, West Virginia University, WVU Eye Institute, One Medical Center Dr, PO Box 9193, Morgantown, WV 26506, USA.,Department of Ophthalmology, Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, Jiangsu Province 225100, China
| | - Ting Zhang
- Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Wei Liu
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA.,Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Yekai Wang
- Departments of Ophthalmology and Biochemistry, West Virginia University, WVU Eye Institute, One Medical Center Dr, PO Box 9193, Morgantown, WV 26506, USA
| | - Rong Xu
- Departments of Ophthalmology and Biochemistry, West Virginia University, WVU Eye Institute, One Medical Center Dr, PO Box 9193, Morgantown, WV 26506, USA
| | - Shaoxue Zeng
- Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Rui Zhang
- Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Siyan Zhu
- Departments of Ophthalmology and Biochemistry, West Virginia University, WVU Eye Institute, One Medical Center Dr, PO Box 9193, Morgantown, WV 26506, USA
| | - Mark C Gillies
- Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Ling Zhu
- Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Jianhai Du
- Departments of Ophthalmology and Biochemistry, West Virginia University, WVU Eye Institute, One Medical Center Dr, PO Box 9193, Morgantown, WV 26506, USA
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56
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Zhang R, Engel AL, Wang Y, Li B, Shen W, Gillies MC, Chao JR, Du J. Inhibition of Mitochondrial Respiration Impairs Nutrient Consumption and Metabolite Transport in Human Retinal Pigment Epithelium. J Proteome Res 2020; 20:909-922. [PMID: 32975122 DOI: 10.1021/acs.jproteome.0c00690] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Mitochondrial respiration in mammalian cells not only generates ATP to meet their own energy needs but also couples with biosynthetic pathways to produce metabolites that can be exported to support neighboring cells. However, how defects in mitochondrial respiration influence these biosynthetic and exporting pathways remains poorly understood. Mitochondrial dysfunction in retinal pigment epithelium (RPE) cells is an emerging contributor to the death of their neighboring photoreceptors in degenerative retinal diseases including age-related macular degeneration. In this study, we used targeted-metabolomics and 13C tracing to investigate how inhibition of mitochondrial respiration influences the intracellular and extracellular metabolome. We found inhibition of mitochondrial respiration strikingly influenced both the intracellular and extracellular metabolome in primary RPE cells. Intriguingly, the extracellular metabolic changes sensitively reflected the intracellular changes. These changes included substantially enhanced glucose consumption and lactate production; reduced release of pyruvate, citrate, and ketone bodies; and massive accumulation of multiple amino acids and nucleosides. In conclusion, these findings reveal a metabolic signature of nutrient consumption and release in mitochondrial dysfunction in RPE cells. Testing medium metabolites provides a sensitive and noninvasive method to assess mitochondrial function in nutrient utilization and transport.
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Affiliation(s)
- Rui Zhang
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506, United States.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, United States.,Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Abbi L Engel
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109, United States
| | - Yekai Wang
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506, United States.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Bo Li
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506, United States.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Weiyong Shen
- Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Mark C Gillies
- Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, NSW 2000, Australia
| | - Jennifer R Chao
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109, United States
| | - Jianhai Du
- Department of Ophthalmology, West Virginia University, Morgantown, West Virginia 26506, United States.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, United States
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57
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Louer EMM, Yi G, Carmone C, Robben J, Stunnenberg HG, den Hollander AI, Deen PMT. Genes Involved in Energy Metabolism Are Differentially Expressed During the Day-Night Cycle in Murine Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2020; 61:49. [PMID: 32460311 PMCID: PMC7405837 DOI: 10.1167/iovs.61.5.49] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Purpose The functional interaction between photoreceptors and retinal pigment epithelium (RPE) cells is essential for vision. Phagocytosis of photoreceptor outer segments (POSs) by the RPE follows a circadian pattern; however, it remains unknown whether other RPE processes follow a daily rhythm. Therefore, our aim was to identify RPE processes following a daily rhythm. Methods Murine RPE was isolated at Zeitgeber time (ZT) 0, 2, 4, 9, 14, and 19 (n = 5 per time point), after which RNA was isolated and sequenced. Genes with a significant difference in expression between time points (P < 0.05) were subjected to EnrichR pathway analysis to identify daily rhythmic processes. Results Pathway enrichment revealed 13 significantly enriched KEGG pathways (P < 0.01), including the metabolic pathway (P = 0.002821). Analysis of the metabolic pathway differentially expressed genes revealed that genes involved in adenosine triphosphate production, glycolysis, glycogenolysis, and glycerophospholipid were low at ZT0 (light onset) and high at ZT19 (night). Genes involved in fatty acid degradation and cholesterol synthesis were high at light onset and low at night. Conclusions Our transcriptome data suggest that the highest energy demand of RPE cells is at night, whereas POS phagocytosis and degradation take place in the morning. Furthermore, we identified genes involved in fatty acid and glycerophospholipid synthesis that are upregulated at night, possibly playing a role in generating building blocks for membrane synthesis.
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58
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Sinha T, Naash MI, Al-Ubaidi MR. The Symbiotic Relationship between the Neural Retina and Retinal Pigment Epithelium Is Supported by Utilizing Differential Metabolic Pathways. iScience 2020; 23:101004. [PMID: 32252018 PMCID: PMC7132098 DOI: 10.1016/j.isci.2020.101004] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 01/09/2020] [Accepted: 03/18/2020] [Indexed: 12/13/2022] Open
Abstract
The neural retina and retinal pigment epithelium (RPE) maintain a symbiotic metabolic relationship, disruption of which leads to debilitating vision loss. The current study was undertaken to identify the differences in the steady-state metabolite levels and the pathways functioning between bona fide neural retina and RPE. Global metabolomics and cluster analyses identified 650 metabolites differentially modulated between the murine neural retina and RPE. Of these, 387 and 163 were higher in the RPE and the neural retina, respectively. Further analysis coupled with transcript and protein level investigations revealed that under normal physiological conditions, the RPE utilizes the pentose phosphate (>3-fold in RPE), serine (>10-fold in RPE), and sphingomyelin biosynthesis (>5-fold in RPE) pathways. Conversely, the neural retina relied mostly on glycolysis. These results show how the RPE and the neural retina have acquired an efficient, complementary and metabolically diverse symbiotic niche to support each other's distinct functions.
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Affiliation(s)
- Tirthankar Sinha
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA.
| | - Muayyad R Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA.
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Hurley JB, Chao JR. Retinal disease: How to use proteomics to speed up diagnosis and metabolomics to slow down degeneration. EBioMedicine 2020; 53:102687. [PMID: 32113163 PMCID: PMC7047175 DOI: 10.1016/j.ebiom.2020.102687] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/09/2020] [Accepted: 02/09/2020] [Indexed: 01/07/2023] Open
Affiliation(s)
- James B Hurley
- Department of Biochemistry, University of Washington, Seattle, WA 98195, United States; Department of Ophthalmology, University of Washington, Seattle, WA 98109, United States.
| | - Jennifer R Chao
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, United States
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60
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Lakkaraju A, Umapathy A, Tan LX, Daniele L, Philp NJ, Boesze-Battaglia K, Williams DS. The cell biology of the retinal pigment epithelium. Prog Retin Eye Res 2020; 78:100846. [PMID: 32105772 PMCID: PMC8941496 DOI: 10.1016/j.preteyeres.2020.100846] [Citation(s) in RCA: 185] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 02/19/2020] [Accepted: 02/23/2020] [Indexed: 02/07/2023]
Abstract
The retinal pigment epithelium (RPE), a monolayer of post-mitotic polarized epithelial cells, strategically situated between the photoreceptors and the choroid, is the primary caretaker of photoreceptor health and function. Dysfunction of the RPE underlies many inherited and acquired diseases that cause permanent blindness. Decades of research have yielded valuable insight into the cell biology of the RPE. In recent years, new technologies such as live-cell imaging have resulted in major advancement in our understanding of areas such as the daily phagocytosis and clearance of photoreceptor outer segment tips, autophagy, endolysosome function, and the metabolic interplay between the RPE and photoreceptors. In this review, we aim to integrate these studies with an emphasis on appropriate models and techniques to investigate RPE cell biology and metabolism, and discuss how RPE cell biology informs our understanding of retinal disease.
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Affiliation(s)
- Aparna Lakkaraju
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Ankita Umapathy
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Li Xuan Tan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Lauren Daniele
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Nancy J Philp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David S Williams
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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61
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Fu Z, Sun Y, Cakir B, Tomita Y, Huang S, Wang Z, Liu CH, S. Cho S, Britton W, S. Kern T, Antonetti DA, Hellström A, E.H. Smith L. Targeting Neurovascular Interaction in Retinal Disorders. Int J Mol Sci 2020; 21:E1503. [PMID: 32098361 PMCID: PMC7073081 DOI: 10.3390/ijms21041503] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/13/2020] [Accepted: 02/21/2020] [Indexed: 02/07/2023] Open
Abstract
The tightly structured neural retina has a unique vascular network comprised of three interconnected plexuses in the inner retina (and choroid for outer retina), which provide oxygen and nutrients to neurons to maintain normal function. Clinical and experimental evidence suggests that neuronal metabolic needs control both normal retinal vascular development and pathological aberrant vascular growth. Particularly, photoreceptors, with the highest density of mitochondria in the body, regulate retinal vascular development by modulating angiogenic and inflammatory factors. Photoreceptor metabolic dysfunction, oxidative stress, and inflammation may cause adaptive but ultimately pathological retinal vascular responses, leading to blindness. Here we focus on the factors involved in neurovascular interactions, which are potential therapeutic targets to decrease energy demand and/or to increase energy production for neovascular retinal disorders.
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Affiliation(s)
- Zhongjie Fu
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
- Manton Center for Orphan Disease, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Ye Sun
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
| | - Bertan Cakir
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
| | - Yohei Tomita
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
| | - Shuo Huang
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
| | - Zhongxiao Wang
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
| | - Chi-Hsiu Liu
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
| | - Steve S. Cho
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
| | - William Britton
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
| | - Timothy S. Kern
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Irvine, CA 92697, USA;
| | - David A. Antonetti
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA;
| | - Ann Hellström
- Section for Ophthalmology, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, 405 30 Göteborg, Sweden;
| | - Lois E.H. Smith
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Z.F.); (Y.S.); (B.C.); (Y.T.); (S.H.); (Z.W.); (C.-H.L.); (S.S.C.); (W.B.)
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62
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Ferrington DA, Fisher CR, Kowluru RA. Mitochondrial Defects Drive Degenerative Retinal Diseases. Trends Mol Med 2020; 26:105-118. [PMID: 31771932 PMCID: PMC6938541 DOI: 10.1016/j.molmed.2019.10.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/16/2019] [Accepted: 10/23/2019] [Indexed: 01/08/2023]
Abstract
Mitochondrial dysfunction is involved in the pathology of two major blinding retinal diseases, diabetic retinopathy (DR) and age-related macular degeneration (AMD). These diseases accumulate mitochondrial defects in distinct retinal subcellular structures, the vascular/neural network in DR and the retinal pigment epithelium (RPE) in AMD. These mitochondrial defects cause a metabolic crisis that drives disease. With no treatments to stop these diseases, coupled with an increasing population suffering from AMD and DR, there is an urgent need to develop new therapeutics targeting the mitochondria to prevent or reverse disease-specific pathology.
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Affiliation(s)
- Deborah A Ferrington
- Department of Ophthalmology and Visual Neurosciences and Graduate Program in Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
| | - Cody R Fisher
- Department of Ophthalmology and Visual Neurosciences and Graduate Program in Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Renu A Kowluru
- Ophthalmology, Vision, and Anatomical Sciences, Wayne State University, Detroit, MI, USA.
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63
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Zhang Q, Presswalla F, Calton M, Charniga C, Stern J, Temple S, Vollrath D, Zacks DN, Ali RR, Thompson DA, Miller JML. Highly Differentiated Human Fetal RPE Cultures Are Resistant to the Accumulation and Toxicity of Lipofuscin-Like Material. Invest Ophthalmol Vis Sci 2019; 60:3468-3479. [PMID: 31408109 PMCID: PMC6692057 DOI: 10.1167/iovs.19-26690] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Purpose The accumulation of undigestible autofluorescent material (UAM), termed lipofuscin in vivo, is a hallmark of aged RPE. Lipofuscin derives, in part, from the incomplete degradation of phagocytized photoreceptor outer segments (OS). Whether this accumulated waste is toxic is unclear. We therefore investigated the effects of UAM in highly differentiated human fetal RPE (hfRPE) cultures. Methods Unmodified and photo-oxidized OS were fed daily to confluent cultures of ARPE-19 RPE or hfRPE. The emission spectrum, composition, and morphology of resulting UAM were measured and compared to in vivo lipofuscin. Effects of UAM on multiple RPE phenotypes were assessed. Results Compared to ARPE-19, hfRPE were markedly less susceptible to UAM buildup. Accumulated UAM in hfRPE initially resembled the morphology of lipofuscin from AMD eyes, but compacted and shifted spectrum over time to resemble lipofuscin from healthy aged human RPE. UAM accumulation mildly reduced transepithelial electrical resistance, ketogenesis, certain RPE differentiation markers, and phagocytosis efficiency, while inducing senescence and rare, focal pockets of epithelial-mesenchymal transition. However, it had no effects on mitochondrial oxygen consumption rate, certain other RPE differentiation markers, secretion of drusen components or polarity markers, nor cell death. Conclusions hfRPE demonstrates a remarkable resistance to UAM accumulation, suggesting mechanisms for efficient OS processing that may be lost in other RPE culture models. Furthermore, while UAM alters hfRPE phenotype, the effects are modest, consistent with conflicting reports in the literature on the toxicity of lipofuscin. Our results suggest that healthy RPE may adequately adapt to and tolerate lipofuscin accumulation.
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Affiliation(s)
- Qitao Zhang
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Feriel Presswalla
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Melissa Calton
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States
| | - Carol Charniga
- Neural Stem Cell Institute, Rensselaer, New York, United States
| | - Jeffrey Stern
- Neural Stem Cell Institute, Rensselaer, New York, United States
| | - Sally Temple
- Neural Stem Cell Institute, Rensselaer, New York, United States
| | - Douglas Vollrath
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States
| | - David N Zacks
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Robin R Ali
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States.,UCL Institute of Ophthalmology, London, United Kingdom
| | - Debra A Thompson
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Jason M L Miller
- Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
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64
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Daniele LL, Caughey J, Volland S, Sharp RC, Dhingra A, Williams DS, Philp NJ, Boesze-Battaglia K. Peroxisome turnover and diurnal modulation of antioxidant activity in retinal pigment epithelia utilizes microtubule-associated protein 1 light chain 3B (LC3B). Am J Physiol Cell Physiol 2019; 317:C1194-C1204. [PMID: 31577510 DOI: 10.1152/ajpcell.00185.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The retinal pigment epithelium (RPE) supports the outer retina through essential roles in the retinoid cycle, nutrient supply, ion exchange, and waste removal. Each day the RPE removes the oldest ~10% of photoreceptor outer segment (OS) disk membranes through phagocytic uptake, which peaks following light onset. Impaired degradation of phagocytosed OS material by the RPE can lead to toxic accumulation of lipids, oxidative tissue damage, inflammation, and cell death. OSs are rich in very long chain fatty acids, which are preferentially catabolized in peroxisomes. Despite the importance of lipid degradation in RPE function, the regulation of peroxisome number and activity relative to diurnal OS ingestion is relatively unexplored. Using immunohistochemistry, immunoblot analysis, and catalase activity assays, we investigated peroxisome abundance and activity at 6 AM, 7 AM (light onset), 8 AM, and 3 PM, in wild-type (WT) mice and mice lacking microtubule-associated protein 1 light chain 3B (Lc3b), which have impaired phagosome degradation. We found that catalase activity, but not the amount of catalase protein, is 50% higher in the morning compared with 3 PM, in RPE of WT, but not Lc3b-/-, mice. Surprisingly, we found that peroxisome abundance was stable during the day in RPE of WT mice; however, numbers were elevated overall in Lc3b-/- mice, implicating LC3B in autophagic organelle turnover in RPE. Our data suggest that RPE peroxisome function is regulated in coordination with phagocytosis, possibly through direct enzyme regulation, and may serve to prepare RPE peroxisomes for daily surges in ingested lipid-rich OS.
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Affiliation(s)
- Lauren L Daniele
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jennifer Caughey
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Stefanie Volland
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, California.,Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Rachel C Sharp
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Anuradha Dhingra
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - David S Williams
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, California.,Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Nancy J Philp
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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65
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Liu B, Calton MA, Abell NS, Benchorin G, Gloudemans MJ, Chen M, Hu J, Li X, Balliu B, Bok D, Montgomery SB, Vollrath D. Genetic analyses of human fetal retinal pigment epithelium gene expression suggest ocular disease mechanisms. Commun Biol 2019; 2:186. [PMID: 31123710 PMCID: PMC6527609 DOI: 10.1038/s42003-019-0430-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Accepted: 04/17/2019] [Indexed: 02/07/2023] Open
Abstract
The retinal pigment epithelium (RPE) serves vital roles in ocular development and retinal homeostasis but has limited representation in large-scale functional genomics datasets. Understanding how common human genetic variants affect RPE gene expression could elucidate the sources of phenotypic variability in selected monogenic ocular diseases and pinpoint causal genes at genome-wide association study (GWAS) loci. We interrogated the genetics of gene expression of cultured human fetal RPE (fRPE) cells under two metabolic conditions and discovered hundreds of shared or condition-specific expression or splice quantitative trait loci (e/sQTLs). Co-localizations of fRPE e/sQTLs with age-related macular degeneration (AMD) and myopia GWAS data suggest new candidate genes, and mechanisms by which a common RDH5 allele contributes to both increased AMD risk and decreased myopia risk. Our study highlights the unique transcriptomic characteristics of fRPE and provides a resource to connect e/sQTLs in a critical ocular cell type to monogenic and complex eye disorders.
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Affiliation(s)
- Boxiang Liu
- Department of Biology, Stanford University, Stanford, CA 94305 USA
| | - Melissa A. Calton
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Nathan S. Abell
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Gillie Benchorin
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Michael J. Gloudemans
- Program in Biomedical Informatics, Stanford University School of Medicine, Stanford, 94305 CA USA
| | - Ming Chen
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Jane Hu
- Department of Ophthalmology, Jules Stein Eye Institute, UCLA, Los Angeles, 90095 CA USA
| | - Xin Li
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Brunilda Balliu
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Dean Bok
- Department of Ophthalmology, Jules Stein Eye Institute, UCLA, Los Angeles, 90095 CA USA
| | - Stephen B. Montgomery
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305 USA
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305 USA
| | - Douglas Vollrath
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305 USA
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66
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Toms M, Burgoyne T, Tracey-White D, Richardson R, Dubis AM, Webster AR, Futter C, Moosajee M. Phagosomal and mitochondrial alterations in RPE may contribute to KCNJ13 retinopathy. Sci Rep 2019; 9:3793. [PMID: 30846767 PMCID: PMC6405871 DOI: 10.1038/s41598-019-40507-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 02/18/2019] [Indexed: 12/29/2022] Open
Abstract
Mutations in KCNJ13 are associated with two retinal disorders; Leber congenital amaurosis (LCA) and snowflake vitreoretinal degeneration (SVD). We examined the retina of kcnj13 mutant zebrafish (obelixtd15, c.502T > C p.[Phe168Leu]) to provide new insights into the pathophysiology underlying these conditions. Detailed phenotyping of obelixtd15 fish revealed a late onset retinal degeneration at 12 months. Electron microscopy of the obelixtd15 retinal pigment epithelium (RPE) uncovered reduced phagosome clearance and increased mitochondrial number and size prior any signs of retinal degeneration. Melanosome distribution was also affected in dark-adapted 12-month obelixtd15 fish. At 6 and 12 months, ATP levels were found to be reduced along with increased expression of glial fibrillary acidic protein and heat shock protein 60. Quantitative RT-PCR of polg2, fis1, opa1, sod1/2 and bcl2a from isolated retina showed expression changes consistent with altered mitochondrial activity and retinal stress. We propose that the retinal disease in this model is primarily a failure of phagosome physiology with a secondary mitochondrial dysfunction. Our findings suggest that alterations in the RPE and photoreceptor cellular organelles may contribute to KCNJ13-related retinal degeneration and provide a therapeutic target.
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Affiliation(s)
- Maria Toms
- UCL Institute of Ophthalmology, London, UK
| | | | | | | | - Adam M Dubis
- UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Andrew R Webster
- UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | | | - Mariya Moosajee
- UCL Institute of Ophthalmology, London, UK. .,Moorfields Eye Hospital NHS Foundation Trust, London, UK. .,Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.
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67
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Leukocyte expression profiles reveal gene sets with prognostic value for seizure-free outcome following stereotactic laser amygdalohippocampotomy. Sci Rep 2019; 9:1086. [PMID: 30705324 PMCID: PMC6355811 DOI: 10.1038/s41598-018-37763-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 12/13/2018] [Indexed: 02/08/2023] Open
Abstract
Among patients with intractable epilepsy, the most commonly performed surgical procedure is craniotomy for amygdalohippocampectomy (AH). Stereotactic laser amygdalohippocampotomy (SLAH) has also been recently employed as a minimally invasive treatment for intractable temporal lobe epilepsy (TLE). Among patients treated with AH and SLAH approximately 65% and 54% of patients become seizure-free, respectively. Therefore, selection criteria for surgical candidates with improved prognostic value for post-operative seizure-free outcome are greatly needed. In this study, we perform RNA sequencing (RNA-Seq) on whole blood leukocyte samples taken from 16 patients with intractable TLE prior to SLAH to test the hypothesis that pre-operative leukocyte RNA expression profiles are prognostic for post-operative seizure outcome. Multidimensional scaling analysis of the RNA expression data indicated separate clustering of patients with seizure free (SF) and non-seizure-free (NSF) outcomes. Differential expression (DE) analysis performed on SF versus NSF groups revealed 24 significantly differentially expressed genes (≥2.0-fold change, p-value < 0.05, FDR <0.05). Network and pathway analyses identified differential activation of pathways involved in lipid metabolism, morphology of oligodendrocytes, inflammatory response, and development of astrocytes. These results suggest that pre-operative leukocyte expression profiles have prognostic value for seizure outcome following SLAH.
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68
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Sinha T, Al-Ubaidi MR, Naash MI. Flavin Imbalance as an Important Player in Diabetic Retinopathy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1185:575-579. [PMID: 31884673 DOI: 10.1007/978-3-030-27378-1_94] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The retina and RPE together constitute the most metabolically active ecosystem in the body, harboring high levels of flavins. Although diabetic patients have been reported to suffer from riboflavin deficiency and use of flavins as nutritional interventions to combat diabetic insult on other tissues have been investigated, such attempts have never been tested for the retina to avoid diabetic retinopathy. Furthermore, the role of flavins in pathophysiology of the retina and RPE has mostly been overlooked. Herein, we review the impact of flavins on various clinical manifestations of diabetic retinopathy and discuss possible ways to address them.
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Affiliation(s)
- Tirthankar Sinha
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA.
| | - Muayyad R Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
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69
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Swarup A, Samuels IS, Bell BA, Han JYS, Du J, Massenzio E, Abel ED, Boesze-Battaglia K, Peachey NS, Philp NJ. Modulating GLUT1 expression in retinal pigment epithelium decreases glucose levels in the retina: impact on photoreceptors and Müller glial cells. Am J Physiol Cell Physiol 2018; 316:C121-C133. [PMID: 30462537 DOI: 10.1152/ajpcell.00410.2018] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The retina is one of the most metabolically active tissues in the body and utilizes glucose to produce energy and intermediates required for daily renewal of photoreceptor cell outer segments. Glucose transporter 1 (GLUT1) facilitates glucose transport across outer blood retinal barrier (BRB) formed by the retinal pigment epithelium (RPE) and the inner BRB formed by the endothelium. We used conditional knockout mice to study the impact of reducing glucose transport across the RPE on photoreceptor and Müller glial cells. Transgenic mice expressing Cre recombinase under control of the Bestrophin1 ( Best1) promoter were bred with Glut1flox/flox mice to generate Tg-Best1-Cre:Glut1flox/flox mice ( RPEΔGlut1). The RPEΔGlut1 mice displayed a mosaic pattern of Cre expression within the RPE that allowed us to analyze mice with ~50% ( RPEΔGlut1m) recombination and mice with >70% ( RPEΔGlut1h) recombination separately. Deletion of GLUT1 from the RPE did not affect its carrier or barrier functions, indicating that the RPE utilizes other substrates to support its metabolic needs thereby sparing glucose for the outer retina. RPEΔGlut1m mice had normal retinal morphology, function, and no cell death; however, where GLUT1 was absent from a span of RPE greater than 100 µm, there was shortening of the photoreceptor cell outer segments. RPEΔGlut1h mice showed outer segment shortening, cell death of photoreceptors, and activation of Müller glial cells. The severe phenotype seen in RPEΔGlut1h mice indicates that glucose transport via the GLUT1 transporter in the RPE is required to meet the anabolic and catabolic requirements of photoreceptors and maintain Müller glial cells in a quiescent state.
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Affiliation(s)
- Aditi Swarup
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University , Philadelphia, Pennsylvania
| | - Ivy S Samuels
- Louis Stokes Cleveland VA Medical Center , Cleveland, Ohio.,Cole Eye Institute, Cleveland Clinic , Cleveland, Ohio
| | - Brent A Bell
- Department of Ophthalmology, University of Pennsylvania , Philadelphia, Pennsylvania
| | - John Y S Han
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University , Philadelphia, Pennsylvania
| | - Jianhai Du
- Department of Ophthalmology, Department of Biochemistry, West Virginia University Eye Institute , Morgantown, West Virginia
| | - Erik Massenzio
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University , Philadelphia, Pennsylvania
| | - E Dale Abel
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa , Iowa City, Iowa.,Division of Endocrinology and Metabolism, Carver College of Medicine, University of Iowa , Iowa City, Iowa
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, Penn Dental Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Neal S Peachey
- Louis Stokes Cleveland VA Medical Center , Cleveland, Ohio.,Cole Eye Institute, Cleveland Clinic , Cleveland, Ohio.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University , Cleveland, Ohio
| | - Nancy J Philp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University , Philadelphia, Pennsylvania
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70
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Sharp RC, Effiom OA, Dhingra A, Odukoya O, Olawuyi A, Arotiba GT, Boesze-Battaglia K, Akintoye SO. Enhanced basal autophagy supports ameloblastoma-derived cell survival and reactivation. Arch Oral Biol 2018; 98:61-67. [PMID: 30465934 DOI: 10.1016/j.archoralbio.2018.11.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 11/07/2018] [Accepted: 11/12/2018] [Indexed: 12/12/2022]
Abstract
OBJECTIVES Ameloblastoma is an aggressive odontogenic jaw neoplasm. Its unlimited growth confers high potential for malignant transformation and recurrence. It is unclear why ameloblastoma is highly recurrent despite surgical resection with a wide margin of normal tissue. While canonical autophagy can be used to degrade and eliminate damaged cellular components, it is also a protective mechanism that provides energy and vital metabolites for cell survival. We used ameloblastoma-derived cells to test the hypothesis that autophagic processes play a role in survival and reactivation of ameloblastoma. METHODS Primary epithelial (EP-AMCs) and mesenchymal (MS-AMCs) ameloblastoma-derived cells were established from tissue samples of solid multicystic ameloblastoma. Clonogenic capacity and basal autophagic capacity were assessed in ameloblastoma-derived cells relative to human odontoma-derived cells (HODCs) and maxilla-mesenchymal stem cells (MX-MSCs). Ability of ameloblastoma-derived cells to survive and form new ameloblastoma was assessed in mouse tumor xenografts. RESULTS EP-AMCs were highly clonogenic (p < 0.0001) and demonstrated enhanced basal levels of autophagic proteins microtubule-associated protein 1-light chain 3 (LC3) (p < 0.01), p62 (Sequestosome 1, SQSTM1) (p < 0.01), and the LC3-adapter, melanoregulin (MREG) (p < 0.05) relative to controls. EP-AMCs xenografts regenerated solid ameloblastoma-like tumor with histological features of columnar ameloblast-like cells, loose stellate reticulum-like cells and regions of cystic degeneration characteristic of follicular variant of solid multicystic ameloblastoma. The xenografts also displayed stromal epithelial invaginations strongly reactive to LC3 and p62 suggestive of epithelial-mesenchymal transition and neoplastic odontogenic epithelium. CONCLUSIONS EP-AMCs exhibit altered autophagic processes that can support survival and recurrence of post-surgical ameloblastoma cells.
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Affiliation(s)
- Rachel C Sharp
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia PA USA
| | - Olajumoke A Effiom
- Department of Oral and Maxillofacial Pathology/Biology, Faculty of Dental Sciences, University of Lagos, Lagos Nigeria
| | - Anuradha Dhingra
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia PA USA
| | - Onatolu Odukoya
- Department of Oral and Maxillofacial Pathology/Biology, Faculty of Dental Sciences, University of Lagos, Lagos Nigeria
| | - Adetokunbo Olawuyi
- Department of Oral and Maxillofacial Pathology/Biology, Faculty of Dental Sciences, University of Lagos, Lagos Nigeria
| | - Godwin T Arotiba
- Department of Oral and Maxillofacial Surgery, Faculty of Dental Sciences, University of Lagos, Lagos Nigeria
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia PA USA
| | - Sunday O Akintoye
- Department of Oral Medicine, School of Dental Medicine, University of Pennsylvania, Philadelphia PA USA.
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71
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Dhingra A, Bell BA, Peachey NS, Daniele LL, Reyes-Reveles J, Sharp RC, Jun B, Bazan NG, Sparrow JR, Kim HJ, Philp NJ, Boesze-Battaglia K. Microtubule-Associated Protein 1 Light Chain 3B, (LC3B) Is Necessary to Maintain Lipid-Mediated Homeostasis in the Retinal Pigment Epithelium. Front Cell Neurosci 2018; 12:351. [PMID: 30349463 PMCID: PMC6186781 DOI: 10.3389/fncel.2018.00351] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 09/19/2018] [Indexed: 12/25/2022] Open
Abstract
Like other neurons, retinal cells utilize autophagic pathways to maintain cell homeostasis. The mammalian retina relies on heterophagy and selective autophagy to efficiently degrade and metabolize ingested lipids with disruption in autophagy associated degradation contributing to age related retinal disorders. The retinal pigment epithelium (RPE) supports photoreceptor cell renewal by daily phagocytosis of shed photoreceptor outer segments (OS). The daily ingestion of these lipid-rich OS imposes a constant degradative burden on these terminally differentiated cells. These cells rely on Microtubule-Associated Protein 1 Light Chain 3 (LC3) family of proteins for phagocytic clearance of the ingested OS. The LC3 family comprises of three highly homologous members, MAP1LC3A (LC3A), MAP1LC3B (LC3B), and MAP1LC3C (LC3C). The purpose of this study was to determine whether the LC3B isoform plays a specific role in maintaining RPE lipid homeostasis. We examined the RPE and retina of the LC3B-/- mouse as a function of age using in vivo ocular imaging and electroretinography coupled with ex vivo, lipidomic analyses of lipid mediators, assessment of bisretinoids as well as imaging of lipid aggregates. Deletion of LC3B resulted in defects within the RPE including increased phagosome accumulation, decreased fatty acid oxidation and a subsequent increase in RPE and sub-RPE lipid deposits. Age-dependent RPE changes included elevated levels of oxidized cholesterol, deposition of 4-HNE lipid peroxidation products, bisretinoid lipofuscin accumulation, and subretinal migration of microglia, collectively likely contributing to loss of retinal function. These observations are consistent with a critical role for LC3B-dependent processes in the maintenance of normal lipid homeostasis in the aging RPE, and suggest that LC3 isoform specific disruption in autophagic processes contribute to AMD-like pathogenesis.
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Affiliation(s)
- Anuradha Dhingra
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Brent A Bell
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Neal S Peachey
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States.,Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Lauren L Daniele
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Juan Reyes-Reveles
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Rachel C Sharp
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Bokkyoo Jun
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Janet R Sparrow
- Department of Ophthalmology, Columbia University Medical Center, New York, NY, United States
| | - Hye Jin Kim
- Department of Ophthalmology, Columbia University Medical Center, New York, NY, United States
| | - Nancy J Philp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
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72
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Luthert PJ, Serrano L, Kiel C. Opportunities and Challenges of Whole-Cell and -Tissue Simulations of the Outer Retina in Health and Disease. Annu Rev Biomed Data Sci 2018. [DOI: 10.1146/annurev-biodatasci-080917-013356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Visual processing starts in the outer retina, where photoreceptor cells sense photons that trigger electrical responses. Retinal pigment epithelial cells are located external to the photoreceptor layer and have critical functions in supporting cell and tissue homeostasis and thus sustaining a healthy retina. The high level of specialization makes the retina vulnerable to alterations that promote retinal degeneration. In this review, we discuss opportunities and challenges in proposing whole-cell and -tissue simulations of the human outer retina. An implicit position taken throughout this review is that mapping diverse data sets onto integrative computational models is likely to be a pivotal approach to understanding complex disease and developing novel interventions.
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Affiliation(s)
- Philip J. Luthert
- Institute of Ophthalmology and National Institute for Health Research (NIHR) Biomedical Research Centre, University College London, London EC1V 9EL, United Kingdom
| | - Luis Serrano
- European Molecular Biology Laboratory (EMBL)/Centre for Genomic Regulation (CRG) Systems Biology Research Unit, Barcelona Institute of Science and Technology, 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
| | - Christina Kiel
- European Molecular Biology Laboratory (EMBL)/Centre for Genomic Regulation (CRG) Systems Biology Research Unit, Barcelona Institute of Science and Technology, 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
- Systems Biology Ireland, Charles Institute of Dermatology, and School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
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73
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Method for measuring extracellular flux from intact polarized epithelial monolayers. Mol Vis 2018; 24:425-433. [PMID: 30034209 PMCID: PMC6031101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 06/23/2018] [Indexed: 12/03/2022] Open
Abstract
PURPOSE The Seahorse XFp platform is widely used for metabolic assessment of cultured cells. Current methods require replating of cells into specialized plates. This is problematic for certain cell types, such as primary human fetal RPE (hfRPE) cells, which must be cultured for months to become properly differentiated. Our goal was to overcome this limitation by devising a method for assaying intact cell monolayers with the Seahorse XFp, without the need for replating. METHODS Primary hfRPE cells were differentiated by prolonged culture on filter inserts. Triangular sections of filters with differentiated cells attached were excised, transferred to XFp cell culture miniplate wells, immobilized at the bottoms, and subjected to mitochondrial stress tests. Replated cells were measured for comparison. Differentiated hfRPE cells were challenged or not with bovine photoreceptor outer segments (POS), and mitochondrial stress tests were performed 3.5 h later, after filter excision and transfer to assay plates. RESULTS Differentiated hfRPE cells assayed following filter excision demonstrated increased maximal respiration, increased spare respiration capacity, and increased extracellular acidification rate (ECAR) relative to replated controls. hfRPE cells challenged with POS exhibited increased maximal respiration and spare capacity, with no apparent change in the ECAR, relative to untreated controls. CONCLUSIONS We have developed a method to reproducibly assay intact, polarized monolayers of hfRPE cells with the Seahorse XFp platform and have shown that the method yields more robust metabolic measurements compared to standard methods and is suitable for assessing the consequences of prolonged perturbations of differentiated cells. We expect our approach to be useful for a variety of studies involving metabolic assessment of adherent cells cultured on filters.
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74
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Fisher CR, Ferrington DA. Perspective on AMD Pathobiology: A Bioenergetic Crisis in the RPE. Invest Ophthalmol Vis Sci 2018; 59:AMD41-AMD47. [PMID: 30025108 PMCID: PMC5989860 DOI: 10.1167/iovs.18-24289] [Citation(s) in RCA: 129] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
AMD is the leading cause of blindness in developed countries. The dry form of AMD, also known as atrophic AMD, is characterized by the death of RPE and photoreceptors. Currently, there are no treatments for this form of the disease due in part to our incomplete understanding of the mechanism causing AMD. Strong experimental evidence from studies of human donors with AMD supports the emerging hypothesis that defects in RPE mitochondria drive AMD pathology. These studies, using different experimental methods, have shown disrupted RPE mitochondrial architecture and decreased mitochondrial number and mass, altered content of multiple mitochondrial proteins, increased mitochondrial DNA damage that correlates with disease severity, and defects in bioenergetics for primary RPE cultures from AMD donors. Herein, we discuss a model of metabolic uncoupling that alters bioenergetics in the diseased retina and drives AMD pathology. These data provide the rationale for targeting the mitochondria in the RPE as the most efficacious intervention strategy if administered early, before vision loss and cell death.
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Affiliation(s)
- Cody R. Fisher
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States
,Graduate Program in Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States
| | - Deborah A. Ferrington
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States
,Graduate Program in Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States
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75
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Yu B, Egbejimi A, Dharmat R, Xu P, Zhao Z, Long B, Miao H, Chen R, Wensel TG, Cai J, Chen Y. Phagocytosed photoreceptor outer segments activate mTORC1 in the retinal pigment epithelium. Sci Signal 2018; 11:11/532/eaag3315. [PMID: 29844054 DOI: 10.1126/scisignal.aag3315] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The retinal pigment epithelium (RPE) transports nutrients and metabolites between the microvascular bed that maintains the outer retina and photoreceptor neurons. The RPE removes photoreceptor outer segments (POS) by receptor-mediated phagocytosis, a process that peaks in the morning. Uptake and degradation of POS initiates signaling cascades in the RPE. Upstream stimuli from various metabolic activities converge on mechanistic target of rapamycin complex 1 (mTORC1), and aberrant mTORC1 signaling is implicated in aging and age-related degeneration of the RPE. We measured mTORC1-mediated responses to RPE phagocytosis in vivo and in vitro. During the morning burst of POS shedding, there was transient activation of mTORC1-mediated signaling in the RPE. POS activated mTORC1 through lysosome-independent mechanisms, and engulfed POS served as a docking platform for mTORC1 assembly. The identification of POS as endogenous stimuli of mTORC1 in the RPE provides a mechanistic link underlying the photoreceptor-RPE interaction in the outer retina.
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Affiliation(s)
- Bo Yu
- Department of Ophthalmology and Visual Science, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Anuoluwapo Egbejimi
- Department of Ophthalmology and Visual Science, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Rachayata Dharmat
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Pei Xu
- Department of Ophthalmology and Visual Science, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Zhenyang Zhao
- Department of Ophthalmology and Visual Science, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Bo Long
- Department of Ophthalmology and Visual Science, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Hongyu Miao
- Department of Biostatistics and Data Science, School of Public Health, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, USA
| | - Theodore G Wensel
- Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jiyang Cai
- Department of Ophthalmology and Visual Science, University of Texas Medical Branch, Galveston, TX 77555, USA.,Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Yan Chen
- Department of Ophthalmology and Visual Science, University of Texas Medical Branch, Galveston, TX 77555, USA. .,Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, TX 77555, USA
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76
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van Leeuwen EM, Emri E, Merle BMJ, Colijn JM, Kersten E, Cougnard-Gregoire A, Dammeier S, Meester-Smoor M, Pool FM, de Jong EK, Delcourt C, Rodrigez-Bocanegra E, Biarnés M, Luthert PJ, Ueffing M, Klaver CCW, Nogoceke E, den Hollander AI, Lengyel I. A new perspective on lipid research in age-related macular degeneration. Prog Retin Eye Res 2018; 67:56-86. [PMID: 29729972 DOI: 10.1016/j.preteyeres.2018.04.006] [Citation(s) in RCA: 150] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/25/2018] [Accepted: 04/30/2018] [Indexed: 12/15/2022]
Abstract
There is an urgency to find new treatment strategies that could prevent or delay the onset or progression of AMD. Different classes of lipids and lipoproteins metabolism genes have been associated with AMD in a multiple ways, but despite the ever-increasing knowledge base, we still do not understand fully how circulating lipids or local lipid metabolism contribute to AMD. It is essential to clarify whether dietary lipids, systemic or local lipoprotein metabolismtrafficking of lipids in the retina should be targeted in the disease. In this article, we critically evaluate what has been reported in the literature and identify new directions needed to bring about a significant advance in our understanding of the role for lipids in AMD. This may help to develop potential new treatment strategies through targeting the lipid homeostasis.
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Affiliation(s)
- Elisabeth M van Leeuwen
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Eszter Emri
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Benedicte M J Merle
- Univ. Bordeaux, Inserm, Bordeaux Population Health Research Center, Team LEHA, UMR 1219, F-33000, Bordeaux, France
| | - Johanna M Colijn
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Eveline Kersten
- Department of Ophthalmology, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behavior, Nijmegen, The Netherlands
| | - Audrey Cougnard-Gregoire
- Univ. Bordeaux, Inserm, Bordeaux Population Health Research Center, Team LEHA, UMR 1219, F-33000, Bordeaux, France
| | - Sascha Dammeier
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Germany
| | - Magda Meester-Smoor
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Eiko K de Jong
- Department of Ophthalmology, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behavior, Nijmegen, The Netherlands
| | - Cécile Delcourt
- Univ. Bordeaux, Inserm, Bordeaux Population Health Research Center, Team LEHA, UMR 1219, F-33000, Bordeaux, France
| | | | | | | | - Marius Ueffing
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Germany
| | - Caroline C W Klaver
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Ophthalmology, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behavior, Nijmegen, The Netherlands
| | - Everson Nogoceke
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Anneke I den Hollander
- Department of Ophthalmology, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behavior, Nijmegen, The Netherlands; Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Imre Lengyel
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom.
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77
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Dejos C, Kuny S, Han WH, Capel H, Lemieux H, Sauvé Y. Photoreceptor-induced RPE phagolysosomal maturation defects in Stargardt-like Maculopathy (STGD3). Sci Rep 2018; 8:5944. [PMID: 29654292 PMCID: PMC5899129 DOI: 10.1038/s41598-018-24357-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 03/28/2018] [Indexed: 11/09/2022] Open
Abstract
For many neurodegenerative disorders, expression of a pathological protein by one cell type impedes function of other cell types, which in turn contributes to the death of the first cell type. In transgenic mice modelling Stargardt-like (STGD3) maculopathy, human mutant ELOVL4 expression by photoreceptors is associated with defects in the underlying retinal pigment epithelium (RPE). To examine how photoreceptors exert cytotoxic effects on RPE cells, transgenic ELOVL4 (TG1-2 line; TG) and wild-type (WT) littermates were studied one month prior (preclinical stage) to onset of photoreceptor loss (two months). TG photoreceptor outer segments presented to human RPE cells are recognized and internalized into phagosomes, but their digestion is delayed. Live RPE cell imaging pinpoints decreased numbers of acidified phagolysomes. In vivo, master regulator of lysosomal genes, transcription factor EB (TFEB), and key lysosomal enzyme Cathepsin D are both unaffected. Oxidative stress, as ruled out with high-resolution respirometry, does not play a role at such an early stage. Upregulation of CRYBA1/A3 and phagocytic cells (microglia/macrophages) interposed between RPE and photoreceptors support adaptive responses to processing delays. Impaired phagolysosomal maturation is observed in RPE of mice expressing human mutant ELOVL4 in their photoreceptors prior to photoreceptor death and associated vision loss.
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Affiliation(s)
- Camille Dejos
- Department of Ophthalmology and Visual Sciences, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada
| | - Sharee Kuny
- Department of Ophthalmology and Visual Sciences, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada
| | - Woo Hyun Han
- Department of Ophthalmology and Visual Sciences, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada
| | - Heather Capel
- Department of Physiology, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada
| | - Hélène Lemieux
- Faculty Saint-Jean, University of Alberta, 8406 Rue Marie-Anne Gaboury Northwest, Edmonton, AB, T6C 4G9, Canada
| | - Yves Sauvé
- Department of Ophthalmology and Visual Sciences, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada. .,Department of Physiology, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada.
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78
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Burgoyne T, Lane A, Laughlin WE, Cheetham ME, Futter CE. Correlative light and immuno-electron microscopy of retinal tissue cryostat sections. PLoS One 2018; 13:e0191048. [PMID: 29315318 PMCID: PMC5760081 DOI: 10.1371/journal.pone.0191048] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 12/27/2017] [Indexed: 11/19/2022] Open
Abstract
Correlative light-electron microscopy (CLEM) is a powerful technique allowing localisation of specific macromolecules within fluorescence microscopy (FM) images to be mapped onto corresponding high-resolution electron microscopy (EM) images. Existing methods are applicable to limited sample types and are technically challenging. Here we describe novel methods to perform CLEM and immuno-electron microscopy (iEM) on cryostat sections utilising the popular FM embedding solution, optimal cutting temperature (OCT) compound. Utilising these approaches, we have (i) identified the same phagosomes by FM and EM in the retinal pigment epithelium (RPE) of retinal tissue (ii) shown the correct localisation of rhodopsin on photoreceptor outer segment disc like-structures in iPSC derived optic cups and (iii) identified a novel interaction between peroxisomes and melanosomes as well as phagosomes in the RPE. These data show that cryostat sections allow easy characterisation of target macromolecule localisation within tissue samples, thus providing a substantial improvement over many conventional methods that are limited to cultured cells. As OCT embedding is routinely used for FM this provides an easily accessible and robust method for further analysis of existing samples by high resolution EM.
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Affiliation(s)
- Thomas Burgoyne
- Institute of Ophthalmology, University College London, London, United Kingdom
- Primary Ciliary Dyskinesia Service, Electron Microscopy Unit, Department of Paediatrics, Royal Brompton Hospital, Sydney Street, London, United Kingdom
| | - Amelia Lane
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - William E. Laughlin
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Michael E. Cheetham
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Clare E. Futter
- Institute of Ophthalmology, University College London, London, United Kingdom
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79
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Boesze-Battaglia K, Walker LP, Dhingra A, Kandror K, Tang HY, Shenker BJ. Internalization of the Active Subunit of the Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin Is Dependent upon Cellugyrin (Synaptogyrin 2), a Host Cell Non-Neuronal Paralog of the Synaptic Vesicle Protein, Synaptogyrin 1. Front Cell Infect Microbiol 2017; 7:469. [PMID: 29184850 PMCID: PMC5694546 DOI: 10.3389/fcimb.2017.00469] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 10/25/2017] [Indexed: 12/17/2022] Open
Abstract
The Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) is a heterotrimeric AB2 toxin capable of inducing lymphocytes, and other cell types, to undergo cell cycle arrest and apoptosis. Exposure to Cdt results in binding to the cell surface followed by internalization and translocation of the active subunit, CdtB, to intracellular compartments. These events are dependent upon toxin binding to cholesterol in the context of lipid rich membrane microdomains often referred to as lipid rafts. We now demonstrate that, in addition to binding to the plasma membrane of lymphocytes, another early and critical event initiated by Cdt is the translocation of the host cell protein, cellugyrin (synaptogyrin-2) to the same cholesterol-rich microdomains. Furthermore, we demonstrate that cellugyrin is an intracellular binding partner for CdtB as demonstrated by immunoprecipitation. Using CRISPR/cas9 gene editing we established a Jurkat cell line deficient in cellugyrin expression (JurkatCg−); these cells were capable of binding Cdt, but unable to internalize CdtB. Furthermore, JurkatCg− cells were not susceptible to Cdt-induced toxicity; these cells failed to exhibit blockade of the PI-3K signaling pathway, cell cycle arrest or cell death. We propose that cellugyrin plays a critical role in the internalization and translocation of CdtB to critical intracellular target sites. These studies provide critical new insight into the mechanism by which Cdt, and in particular, CdtB is able to induce toxicity.
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Affiliation(s)
- Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Lisa P Walker
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Anuradha Dhingra
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Konstantin Kandror
- Department of Biochemistry, School of Medicine, Boston University, Boston, MA, United States
| | - Hsin-Yao Tang
- Wistar Proteomics and Metabolomics Core Facility, Wistar Institute, Philadelphia, PA, United States
| | - Bruce J Shenker
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
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80
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Kanow MA, Giarmarco MM, Jankowski CS, Tsantilas K, Engel AL, Du J, Linton JD, Farnsworth CC, Sloat SR, Rountree A, Sweet IR, Lindsay KJ, Parker ED, Brockerhoff SE, Sadilek M, Chao JR, Hurley JB. Biochemical adaptations of the retina and retinal pigment epithelium support a metabolic ecosystem in the vertebrate eye. eLife 2017; 6:28899. [PMID: 28901286 PMCID: PMC5617631 DOI: 10.7554/elife.28899] [Citation(s) in RCA: 236] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/12/2017] [Indexed: 12/12/2022] Open
Abstract
Here we report multiple lines of evidence for a comprehensive model of energy metabolism in the vertebrate eye. Metabolic flux, locations of key enzymes, and our finding that glucose enters mouse and zebrafish retinas mostly through photoreceptors support a conceptually new model for retinal metabolism. In this model, glucose from the choroidal blood passes through the retinal pigment epithelium to the retina where photoreceptors convert it to lactate. Photoreceptors then export the lactate as fuel for the retinal pigment epithelium and for neighboring Müller glial cells. We used human retinal epithelial cells to show that lactate can suppress consumption of glucose by the retinal pigment epithelium. Suppression of glucose consumption in the retinal pigment epithelium can increase the amount of glucose that reaches the retina. This framework for understanding metabolic relationships in the vertebrate retina provides new insights into the underlying causes of retinal disease and age-related vision loss.
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Affiliation(s)
- Mark A Kanow
- Department of Biochemistry, University of Washington, Seattle, United States
| | | | - Connor Sr Jankowski
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Kristine Tsantilas
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Abbi L Engel
- Department of Ophthalmology, University of Washington, Seattle, United States
| | - Jianhai Du
- Department of Ophthalmology, West Virginia University, Morgantown, United States.,Department of Biochemistry, West Virginia University, Morgantown, United States
| | - Jonathan D Linton
- Department of Biochemistry, University of Washington, Seattle, United States.,Department of Ophthalmology, University of Washington, Seattle, United States
| | | | - Stephanie R Sloat
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Austin Rountree
- Department of Medicine, UW Diabetes Institute, University of Washington, Seattle, United States
| | - Ian R Sweet
- Department of Medicine, UW Diabetes Institute, University of Washington, Seattle, United States
| | - Ken J Lindsay
- Department of Biochemistry, University of Washington, Seattle, United States.,Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Edward D Parker
- Department of Ophthalmology, University of Washington, Seattle, United States
| | - Susan E Brockerhoff
- Department of Biochemistry, University of Washington, Seattle, United States.,Department of Ophthalmology, University of Washington, Seattle, United States
| | - Martin Sadilek
- Department of Chemistry, University of Washington, Seattle, United States
| | - Jennifer R Chao
- Department of Ophthalmology, University of Washington, Seattle, United States
| | - James B Hurley
- Department of Biochemistry, University of Washington, Seattle, United States.,Department of Ophthalmology, University of Washington, Seattle, United States
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