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Karmoker JR, Bounds SE, Cai J. Aryl hydrocarbon receptor (AhR)-mediated immune responses to degeneration of the retinal pigment epithelium. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167351. [PMID: 39004382 DOI: 10.1016/j.bbadis.2024.167351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 07/05/2024] [Accepted: 07/08/2024] [Indexed: 07/16/2024]
Abstract
Injuries to the retinal pigment epithelium (RPE) trigger immune responses, orchestrating interactions within the innate and adaptive immune systems in the outer retina and choroid. We previously reported that interleukin 17 (IL-17) is a pivotal signaling molecule originating from choroidal γδ T cells, exerting protective effects by mediating functional connections between the RPE and subretinal microglia. In this current study, we generated mice with aryl hydrocarbon receptor (AhR) knockout specifically in IL-17-producing cells. These animals had deficiency in IL-17 production from γδ T cells, and exhibited increased sensitivity to both acute and chronic insults targeting the RPE. These findings imply that IL-17 plays a crucial role as a signaling cytokine in preserving the homeostasis of the outer retina and choroid.
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Affiliation(s)
- James Regun Karmoker
- Department of Biochemistry & Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
| | - Sarah E Bounds
- Department of Biochemistry & Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
| | - Jiyang Cai
- Department of Biochemistry & Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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2
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Puertas-Neyra K, Coco-Martin RM, Hernandez-Rodriguez LA, Gobelli D, Garcia-Ferrer Y, Palma-Vecino R, Tellería JJ, Simarro M, de la Fuente MA, Fernandez-Bueno I. Clinical exome analysis and targeted gene repair of the c.1354dupT variant in iPSC lines from patients with PROM1-related retinopathies exhibiting diverse phenotypes. Stem Cell Res Ther 2024; 15:192. [PMID: 38956727 PMCID: PMC11218195 DOI: 10.1186/s13287-024-03804-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 06/16/2024] [Indexed: 07/04/2024] Open
Abstract
BACKGROUND Inherited retinal dystrophies (IRD) are one of the main causes of incurable blindness worldwide. IRD are caused by mutations in genes that encode essential proteins for the retina, leading to photoreceptor degeneration and loss of visual function. IRD generates an enormous global financial burden due to the lack of understanding of a significant part of its pathophysiology, molecular diagnosis, and the near absence of non-palliative treatment options. Patient-derived induced pluripotent stem cells (iPSC) for IRD seem to be an excellent option for addressing these questions, serving as exceptional tools for in-depth studies of IRD pathophysiology and testing new therapeutic approaches. METHODS From a cohort of 8 patients with PROM1-related IRD, we identified 3 patients carrying the same variant (c.1354dupT) but expressing three different IRD phenotypes: Cone and rod dystrophy (CORD), Retinitis pigmentosa (RP), and Stargardt disease type 4 (STGD4). These three target patients, along with one healthy relative from each, underwent comprehensive ophthalmic examinations and their genetic panel study was expanded through clinical exome sequencing (CES). Subsequently, non-integrative patient-derived iPSC were generated and fully characterized. Correction of the c.1354dupT mutation was performed using CRISPR/Cas9, and the genetic restoration of the PROM1 gene was confirmed through flow cytometry and western blotting in the patient-derived iPSC lines. RESULTS CES revealed that 2 target patients with the c.1354dupT mutation presented monoallelic variants in genes associated with the complement system or photoreceptor differentiation and peroxisome biogenesis disorders, respectively. The pluripotency and functionality of the patient-derived iPSC lines were confirmed, and the correction of the target mutation fully restored the capability of encoding Prominin-1 (CD133) in the genetically repaired patient-derived iPSC lines. CONCLUSIONS The c.1354dupT mutation in the PROM1 gene is associated to three distinct AR phenotypes of IRD. This pleotropic effect might be related to the influence of monoallelic variants in other genes associated with retinal dystrophies. However, further evidence needs to be provided. Future experiments should include gene-edited patient-derived iPSC due to its potential as disease modelling tools to elucidate this matter in question.
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Affiliation(s)
- Kevin Puertas-Neyra
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Universidad de Valladolid, Valladolid, Spain
| | - Rosa M Coco-Martin
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Universidad de Valladolid, Valladolid, Spain.
- Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS-REI), Inflamación E Inmunopatologia de Organos y Sistemas, Instituto de Salud Carlos III, Valladolid, Spain.
- Centro en Red de Medicina Regenerativa, y Terapia Celular de Castilla y León, Valladolid, Spain.
| | | | - Dino Gobelli
- Unidad de Excelencia Instituto de Biomedicina y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
- Departamento de Biología Celular, Genética, Histología y Farmacología, Facultad de Medicina, Universidad de Valladolid, Valladolid, Spain
| | - Yenisey Garcia-Ferrer
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Universidad de Valladolid, Valladolid, Spain
| | - Raicel Palma-Vecino
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Universidad de Valladolid, Valladolid, Spain
| | - Juan José Tellería
- Unidad de Excelencia Instituto de Biomedicina y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Maria Simarro
- Unidad de Excelencia Instituto de Biomedicina y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
- Departamento de Biología Celular, Genética, Histología y Farmacología, Facultad de Medicina, Universidad de Valladolid, Valladolid, Spain
| | - Miguel A de la Fuente
- Unidad de Excelencia Instituto de Biomedicina y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
- Departamento de Biología Celular, Genética, Histología y Farmacología, Facultad de Medicina, Universidad de Valladolid, Valladolid, Spain
| | - Ivan Fernandez-Bueno
- Instituto Universitario de Oftalmobiología Aplicada (IOBA), Universidad de Valladolid, Valladolid, Spain
- Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS-REI), Inflamación E Inmunopatologia de Organos y Sistemas, Instituto de Salud Carlos III, Valladolid, Spain
- Centro en Red de Medicina Regenerativa, y Terapia Celular de Castilla y León, Valladolid, Spain
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3
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Singh C. Systems levels analysis of lipid metabolism in oxygen-induced retinopathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.21.568200. [PMID: 38045301 PMCID: PMC10690220 DOI: 10.1101/2023.11.21.568200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Hyperoxia induces glutamine-fueled anaplerosis in the Muller cells, endothelial cells, and retinal explants. Anaplerosis takes away glutamine from the biosynthetic pathway to the energy-producing TCA cycle. This process depletes biosynthetic precursors from newly proliferating endothelial cells. The induction of anaplerosis in the hyperoxic retina is a compensatory response, either to decreased glycolysis or decreased flux from glycolysis to the TCA cycle. We hypothesized that by providing substrates that feed into TCA, we could reverse or prevent glutamine-fueled anaplerosis, thereby abating the glutamine wastage for energy generation. Using an oxygen-induced retinopathy (OIR) mouse model, we first compared the difference in fatty acid metabolism between OIR-resistant BALB/cByJ and OIR susceptible C57BL/6J strains to understand if these strains exhibit metabolic difference that protects BALB/cByJ from the hyperoxic conditions and prevents their vasculature in oxygen-induced retinopathy model. Based on our findings from the metabolic comparison between two mouse strains, we hypothesized that the medium-chain fatty acid, octanoate, can feed into the TCA and serve as an alternative energy source in response to hyperoxia. Our systems levels analysis of OIR model shows that the medium chain fatty acid can serve as an alternative source to feed TCA. We here, for the first time, demonstrate that the retina can use medium-chain fatty acid octanoate to replenish TCA in normoxic and at a higher rate in hyperoxic conditions.
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4
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Sun T, Huang K, Niu K, Lin C, Liu W, Yeh C, Kuo S, Chang C. Hyperbaric oxygen therapy suppresses hypoxia and reoxygenation injury to retinal pigment epithelial cells through activating peroxisome proliferator activator receptor-alpha signalling. J Cell Mol Med 2023; 27:3189-3201. [PMID: 37731202 PMCID: PMC10568664 DOI: 10.1111/jcmm.17963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 09/22/2023] Open
Abstract
Retinal ischemia followed by reperfusion (IR) is a common cause of many ocular disorders, such as age-related macular degeneration (AMD), which leads to blindness in the elderly population, and proper therapies remain unavailable. Retinal pigment epithelial (RPE) cell death is a hallmark of AMD. Hyperbaric oxygen (HBO) therapy can improve IR tissue survival by inducing ischemic preconditioning responses. We conducted an in vitro study to examine the effects of HBO preconditioning on oxygen-glucose deprivation (OGD)-induced IR-injured RPE cells. RPE cells were treated with HBO (100% O2 at 3 atmospheres absolute for 90 min) once a day for three consecutive days before retinal IR onset. Compared with normal cells, the IR-injured RPE cells had lower cell viability, lower peroxisome proliferator activator receptor-alpha (PPAR-α) expression, more severe oxidation status, higher blood-retinal barrier disruption and more elevated apoptosis and autophagy rates. HBO preconditioning increased PPAR-α expression, improved cell viability, decreased oxidative stress, blood-retinal barrier disruption and cellular apoptosis and autophagy. A specific PPAR-α antagonist, GW6471, antagonized all the protective effects of HBO preconditioning in IR-injured RPE cells. Combining these observations, HBO therapy can reverse OGD-induced RPE cell injury by activating PPAR-α signalling.
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Affiliation(s)
- Tzong‐Bor Sun
- Department of Hyperbaric Oxygen MedicineChi Mei Medical CenterTainanTaiwan
- Division of Plastic Surgery, Department of SurgeryChi Mei Medical CenterTainanTaiwan
- Department of Biotechnology and Food TechnologySouthern Taiwan University of Science and TechnologyTainanTaiwan
| | - Kuo‐Feng Huang
- Division of Plastic Surgery, Department of SurgeryChi Mei Medical CenterTainanTaiwan
| | - Ko‐Chi Niu
- Department of Hyperbaric Oxygen MedicineChi Mei Medical CenterTainanTaiwan
| | - Cheng‐Hsien Lin
- Department of MedicineMackay Medical CollegeNew Taipei CityTaiwan
- Department of Medical ResearchChi Mei Medical CenterTainanTaiwan
| | - Wen‐Pin Liu
- Department of Medical ResearchChi Mei Medical CenterTainanTaiwan
| | - Chao‐Hung Yeh
- Division of Neurosurgery, Department of SurgeryChi Mei Medical CenterTainanTaiwan
- Department of OptometryChung Hwa University of Medical TechnologyTainanTaiwan
| | - Shu‐Chun Kuo
- Department of OptometryChung Hwa University of Medical TechnologyTainanTaiwan
- Department of OphthalmologyChi Mei Medical CenterTainanTaiwan
| | - Ching‐Ping Chang
- Department of Medical ResearchChi Mei Medical CenterTainanTaiwan
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5
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Jiménez-Loygorri JI, Benítez-Fernández R, Viedma-Poyatos Á, Zapata-Muñoz J, Villarejo-Zori B, Gómez-Sintes R, Boya P. Mitophagy in the retina: Viewing mitochondrial homeostasis through a new lens. Prog Retin Eye Res 2023; 96:101205. [PMID: 37454969 DOI: 10.1016/j.preteyeres.2023.101205] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 07/11/2023] [Accepted: 07/13/2023] [Indexed: 07/18/2023]
Abstract
Mitochondrial function is key to support metabolism and homeostasis in the retina, an organ that has one of the highest metabolic rates body-wide and is constantly exposed to photooxidative damage and external stressors. Mitophagy is the selective autophagic degradation of mitochondria within lysosomes, and can be triggered by distinct stimuli such as mitochondrial damage or hypoxia. Here, we review the importance of mitophagy in retinal physiology and pathology. In the developing retina, mitophagy is essential for metabolic reprogramming and differentiation of retina ganglion cells (RGCs). In basal conditions, mitophagy acts as a quality control mechanism, maintaining a healthy mitochondrial pool to meet cellular demands. We summarize the different autophagy- and mitophagy-deficient mouse models described in the literature, and discuss the potential role of mitophagy dysregulation in retinal diseases such as glaucoma, diabetic retinopathy, retinitis pigmentosa, and age-related macular degeneration. Finally, we provide an overview of methods used to monitor mitophagy in vitro, ex vivo, and in vivo. This review highlights the important role of mitophagy in sustaining visual function, and its potential as a putative therapeutic target for retinal and other diseases.
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Affiliation(s)
- Juan Ignacio Jiménez-Loygorri
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain.
| | - Rocío Benítez-Fernández
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain; Departament of Neuroscience and Movement Science, Faculty of Science and Medicine, University of Fribourg, 1700, Fribourg, Switzerland
| | - Álvaro Viedma-Poyatos
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Juan Zapata-Muñoz
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Beatriz Villarejo-Zori
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Raquel Gómez-Sintes
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Patricia Boya
- Autophagy Lab, Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain; Departament of Neuroscience and Movement Science, Faculty of Science and Medicine, University of Fribourg, 1700, Fribourg, Switzerland.
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6
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Lee J, Hu Z, Wang YA, Nath D, Liang W, Cui Y, Ma JX, Duerfeldt AS. Design, Synthesis, and Structure-Activity Relationships of Biaryl Anilines as Subtype-Selective PPAR-alpha Agonists. ACS Med Chem Lett 2023; 14:766-776. [PMID: 37312852 PMCID: PMC10258832 DOI: 10.1021/acsmedchemlett.3c00056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 05/16/2023] [Indexed: 06/15/2023] Open
Abstract
The role of peroxisome proliferator-activated receptor alpha (PPARα) in retinal biology is clarifying, and evidence demonstrates that novel PPARα agonists hold promising therapeutic utility for diseases like diabetic retinopathy and age-related macular degeneration. Herein, we disclose the design and initial structure-activity relationships for a new biaryl aniline PPARα agonistic chemotype. Notably, this series exhibits subtype selectivity for PPARα over other isoforms, a phenomenon postulated to be due to the unique benzoic acid headgroup. This biphenyl aniline series is sensitive to B-ring functionalization but allows isosteric replacement, and provides an opportunity for C-ring extension. From this series, 3g, 6j, and 6d were identified as leads with <90 nM potency in a cell-based luciferase assay cell and exhibited efficacy in various disease-relevant cell contexts, thereby setting the stage for further characterization in more advanced in vitro and in vivo models.
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Affiliation(s)
- Julia
J. Lee
- Department
of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Ziwei Hu
- Department
of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Yuhong Anna Wang
- Department
of Physiology, University of Oklahoma Health
Sciences Center, Oklahoma
City, Oklahoma 73104, United States
| | - Dinesh Nath
- Department
of Chemistry and Biochemistry, University
of Oklahoma, Norman, Oklahoma 73019, United
States
| | - Wentao Liang
- Department
of Biochemistry, Wake Forest School of Medicine, Winston-Salem, North Carolina 27101, United States
| | - Yi Cui
- Department
of Biochemistry, Wake Forest School of Medicine, Winston-Salem, North Carolina 27101, United States
- Department
of Ophthalmology, Fujian Medical University
Union Hospital, Fujian 350001, China
| | - Jian-Xing Ma
- Department
of Biochemistry, Wake Forest School of Medicine, Winston-Salem, North Carolina 27101, United States
| | - Adam S. Duerfeldt
- Department
of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
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7
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Liang W, Huang L, Whelchel A, Yuan T, Ma X, Cheng R, Takahashi Y, Karamichos D, Ma JX. Peroxisome proliferator-activated receptor-α (PPARα) regulates wound healing and mitochondrial metabolism in the cornea. Proc Natl Acad Sci U S A 2023; 120:e2217576120. [PMID: 36943878 PMCID: PMC10068757 DOI: 10.1073/pnas.2217576120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/14/2023] [Indexed: 03/23/2023] Open
Abstract
Diabetes can result in impaired corneal wound healing. Mitochondrial dysfunction plays an important role in diabetic complications. However, the regulation of mitochondria function in the diabetic cornea and its impacts on wound healing remain elusive. The present study aimed to explore the molecular basis for the disturbed mitochondrial metabolism and subsequent wound healing impairment in the diabetic cornea. Seahorse analysis showed that mitochondrial oxidative phosphorylation is a major source of ATP production in human corneal epithelial cells. Live corneal biopsy punches from type 1 and type 2 diabetic mouse models showed impaired mitochondrial functions, correlating with impaired corneal wound healing, compared to nondiabetic controls. To approach the molecular basis for the impaired mitochondrial function, we found that Peroxisome Proliferator-Activated Receptor-α (PPARα) expression was downregulated in diabetic human corneas. Even without diabetes, global PPARα knockout mice and corneal epithelium-specific PPARα conditional knockout mice showed disturbed mitochondrial function and delayed wound healing in the cornea, similar to that in diabetic corneas. In contrast, fenofibrate, a PPARα agonist, ameliorated mitochondrial dysfunction and enhanced wound healing in the corneas of diabetic mice. Similarly, corneal epithelium-specific PPARα transgenic overexpression improved mitochondrial function and enhanced wound healing in the cornea. Furthermore, PPARα agonist ameliorated the mitochondrial dysfunction in primary human corneal epithelial cells exposed to diabetic stressors, which was impeded by siRNA knockdown of PPARα, suggesting a PPARα-dependent mechanism. These findings suggest that downregulation of PPARα plays an important role in the impaired mitochondrial function in the corneal epithelium and delayed corneal wound healing in diabetes.
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Affiliation(s)
- Wentao Liang
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK73104
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC27157
| | - Li Huang
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC27157
- Department of Ophthalmology, Fujian Medical University Union Hospital, Fuzhou350000, China
| | - Amy Whelchel
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK73104
| | - Tian Yuan
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC27157
| | - Xiang Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK73104
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC27157
| | - Rui Cheng
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC27157
| | - Yusuke Takahashi
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC27157
| | - Dimitrios Karamichos
- Division of Research and Innovation, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX76107
- Department of Pharmaceutical Sciences, University of North Texas Health Science Center, Fort Worth, TX76107
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX76107
| | - Jian-Xing Ma
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC27157
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Todorova V, Stauffacher MF, Ravotto L, Nötzli S, Karademir D, Ebner LJA, Imsand C, Merolla L, Hauck SM, Samardzija M, Saab AS, Barros LF, Weber B, Grimm C. Deficits in mitochondrial TCA cycle and OXPHOS precede rod photoreceptor degeneration during chronic HIF activation. Mol Neurodegener 2023; 18:15. [PMID: 36882871 PMCID: PMC9990367 DOI: 10.1186/s13024-023-00602-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 02/03/2023] [Indexed: 03/09/2023] Open
Abstract
BACKGROUND Major retinal degenerative diseases, including age-related macular degeneration, diabetic retinopathy and retinal detachment, are associated with a local decrease in oxygen availability causing the formation of hypoxic areas affecting the photoreceptor (PR) cells. Here, we addressed the underlying pathological mechanisms of PR degeneration by focusing on energy metabolism during chronic activation of hypoxia-inducible factors (HIFs) in rod PR. METHODS We used two-photon laser scanning microscopy (TPLSM) of genetically encoded biosensors delivered by adeno-associated viruses (AAV) to determine lactate and glucose dynamics in PR and inner retinal cells. Retinal layer-specific proteomics, in situ enzymatic assays and immunofluorescence studies were used to analyse mitochondrial metabolism in rod PRs during chronic HIF activation. RESULTS PRs exhibited remarkably higher glycolytic flux through the hexokinases than neurons of the inner retina. Chronic HIF activation in rods did not cause overt change in glucose dynamics but an increase in lactate production nonetheless. Furthermore, dysregulation of the oxidative phosphorylation pathway (OXPHOS) and tricarboxylic acid (TCA) cycle in rods with an activated hypoxic response decelerated cellular anabolism causing shortening of rod photoreceptor outer segments (OS) before onset of cell degeneration. Interestingly, rods with deficient OXPHOS but an intact TCA cycle did not exhibit these early signs of anabolic dysregulation and showed a slower course of degeneration. CONCLUSION Together, these data indicate an exceeding high glycolytic flux in rods and highlight the importance of mitochondrial metabolism and especially of the TCA cycle for PR survival in conditions of increased HIF activity.
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Affiliation(s)
- Vyara Todorova
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Mia Fee Stauffacher
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Luca Ravotto
- Institute of Pharmacology and Toxicology and Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland
| | - Sarah Nötzli
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Duygu Karademir
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Lynn J A Ebner
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Cornelia Imsand
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Luca Merolla
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Stefanie M Hauck
- Metabolomics and Proteomics Core, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764, Munich, Germany
| | - Marijana Samardzija
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology and Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland
| | - L Felipe Barros
- Centro de Estudios Científicos (CECs), Valdivia, Chile.,Universidad San Sebastián, Valdivia, Chile
| | - Bruno Weber
- Institute of Pharmacology and Toxicology and Neuroscience Center Zurich, University and ETH Zurich, Winterthurerstr. 190, 8057, Zurich, Switzerland
| | - Christian Grimm
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Wagistrasse 14, 8952, Schlieren, Switzerland.
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9
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Yuan T, Dong L, Pearsall EA, Zhou K, Cheng R, Ma JX. The Protective Role of Microglial PPARα in Diabetic Retinal Neurodegeneration and Neurovascular Dysfunction. Cells 2022; 11:cells11233869. [PMID: 36497130 PMCID: PMC9739170 DOI: 10.3390/cells11233869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022] Open
Abstract
Microglial activation and subsequent pathological neuroinflammation contribute to diabetic retinopathy (DR). However, the underlying mechanisms of microgliosis, and means to effectively suppress pathological microgliosis, remain incompletely understood. Peroxisome proliferator-activated receptor alpha (PPARα) is a transcription factor that regulates lipid metabolism. The present study aimed to determine if PPARα affects pathological microgliosis in DR. In global Pparα mice, retinal microglia exhibited decreased structural complexity and enlarged cell bodies, suggesting microglial activation. Microglia-specific conditional Pparα-/- (PCKO) mice showed decreased retinal thickness as revealed by optical coherence tomography. Under streptozotocin (STZ)-induced diabetes, diabetic PCKO mice exhibited decreased electroretinography response, while diabetes-induced retinal dysfunction was alleviated in diabetic microglia-specific Pparα-transgenic (PCTG) mice. Additionally, diabetes-induced retinal pericyte loss was exacerbated in diabetic PCKO mice and alleviated in diabetic PCTG mice. In cultured microglial cells with the diabetic stressor 4-HNE, metabolic flux analysis demonstrated that Pparα ablation caused a metabolic shift from oxidative phosphorylation to glycolysis. Pparα deficiency also increased microglial STING and TNF-α expression. Taken together, these findings revealed a critical role for PPARα in pathological microgliosis, neurodegeneration, and vascular damage in DR, providing insight into the underlying molecular mechanisms of microgliosis in this context and suggesting microglial PPARα as a potential therapeutic target.
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Affiliation(s)
- Tian Yuan
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Lijie Dong
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China
| | - Elizabeth A. Pearsall
- Vision Research Center, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Kelu Zhou
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Rui Cheng
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
- Correspondence: (R.C.); (J.-X.M.); Tel.: +1-336-716-3914 (R.C.); +1-336-716-4676 (J.-X.M.)
| | - Jian-Xing Ma
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
- Correspondence: (R.C.); (J.-X.M.); Tel.: +1-336-716-3914 (R.C.); +1-336-716-4676 (J.-X.M.)
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10
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Short-Term Omega-3 Supplementation Modulates Novel Neurovascular and Fatty Acid Metabolic Proteome Changes in the Retina and Ophthalmic Artery of Mice with Targeted Cyp2c44 Gene Deletion. Cells 2022; 11:cells11213494. [PMID: 36359890 PMCID: PMC9658563 DOI: 10.3390/cells11213494] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/27/2022] [Accepted: 11/02/2022] [Indexed: 11/06/2022] Open
Abstract
Cytochrome P450 (CYP) gene mutations are a common predisposition associated with glaucoma. Although the molecular mechanisms are largely unknown, omega-3 polyunsaturated fatty acids (ω-3 PUFA) and their CYP-derived bioactive mediators play crucial roles in the ocular system. Here, we elucidated the proteome and cell-signalling alterations attributed to the main human CYP2C gene deficiency using a homologous murine model (Cyp2c44−/−), and unravelled the effects of acute ω-3 PUFA supplementation in two ocular vascular beds comprising the retrobulbar ophthalmic artery (OA) and retina (R). Male Cyp2c44−/− mice (KO) and their floxed littermates (WT) were gavaged daily for 7 days with 0.01 mL/g of ω-3 PUFA composed of menhaden fish oil. Another group in respective strains served as vehicle-treated controls. OA and R were isolated at day 8 post-treatment (n = 9/group) and subjected to mass spectrometry (MS)-based proteomics and in silico bioinformatics analyses. Cyp2c44−/− resulted in significant detrimental proteome changes associated with compromised vascular integrity and degeneration in the OA and R, respectively. However, notable changes in the OA after ω-3 PUFA intake were associated with the maintenance of intercellular junctional and endothelial cell functions, as well as activation of the fatty acid metabolic pathway in the KO mice. Conversely, ω-3 PUFA supplementation profoundly influenced the regulation of a large majority of retinal proteins involved in the preservation of neuronal and phototransduction activities in WT mice, namely synaptophysin, phosducin and guanylate cyclase-1, while significantly abrogating degenerative processes in the KO mice via the regulation of, namely, synaptotagmin-1 and beta-crystallin B2. In gist, this study demonstrated that dietary supplementation with ω-3 PUFA for a short period of seven days regulated specific neuro-vasculoprotective mechanisms to preserve the functionality of the OA and R in the absence of Cyp2c44. The potential adjunct use of ω-3 PUFA for glaucoma therapy needs further investigation.
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11
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Rehman S, Gora AH, Varshney S, Dias J, Olsvik PA, Fernandes JMO, Brugman S, Kiron V. Developmental defects and behavioral changes in a diet-induced inflammation model of zebrafish. Front Immunol 2022; 13:1018768. [PMID: 36389790 PMCID: PMC9643868 DOI: 10.3389/fimmu.2022.1018768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Accepted: 10/03/2022] [Indexed: 12/03/2022] Open
Abstract
Soybean meal evokes diet-induced intestinal inflammation in certain fishes. Although the molecular aspects of soybean-induced intestinal inflammation in zebrafish are known, the impact of the inflammatory diet on fish behavior remain largely underexplored. We fed zebrafish larvae with three diets - control, soybean meal and soybean meal with β-glucan to gain deeper insight into the behavioral changes associated with the soybean meal-induced inflammation model. We assessed the effect of the diets on the locomotor behavior, morphological development, oxygen consumption and larval transcriptome. Our study revealed that dietary soybean meal can reduce the locomotor activity, induce developmental defects and increase the oxygen demand in zebrafish larvae. Transcriptomic analysis pointed to the suppression of genes linked to visual perception, organ development, phototransduction pathway and activation of genes linked to the steroid biosynthesis pathway. On the contrary, β-glucan, an anti-inflammatory feed additive, counteracted the behavioral and phenotypic changes linked to dietary soybean. Although we did not identify any differentially expressed genes from the soybean meal alone fed group vs soybean meal + β-glucan-fed group comparison, the unique genes from the comparisons of the two groups with the control likely indicate reduction in inflammatory cytokine signaling, inhibition of proteolysis and induction of epigenetic modifications by the dietary glucan. Furthermore, we found that feeding an inflammatory diet at the larval stage can lead to long-lasting developmental defects. In conclusion, our study reveals the extra-intestinal manifestations associated with soybean meal-induced inflammation model.
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Affiliation(s)
- Saima Rehman
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Adnan H. Gora
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Shubham Varshney
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | | | - Pål A. Olsvik
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | | | - Sylvia Brugman
- Department of Animal Sciences, Host Microbe Interactomics, Wageningen University, Wageningen, Netherlands
| | - Viswanath Kiron
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
- *Correspondence: Viswanath Kiron,
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12
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Ren J, Ren A, Deng X, Huang Z, Jiang Z, Li Z, Gong Y. Long-Chain Polyunsaturated Fatty Acids and Their Metabolites Regulate Inflammation in Age-Related Macular Degeneration. J Inflamm Res 2022; 15:865-880. [PMID: 35173457 PMCID: PMC8842733 DOI: 10.2147/jir.s347231] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 01/20/2022] [Indexed: 12/24/2022] Open
Abstract
Age-related macular degeneration (AMD) is a blinding eye disease, whose incidence strongly increases with ages. The etiology of AMD is complex, including aging, abnormal lipid metabolism, chronic inflammation and oxidative stress. Long-chain polyunsaturated fatty acids (LCPUFA) are essential for ocular structures and functions. This review summarizes the regulatory effects of LCPUFA on inflammation in AMD. LCPUFA are related to aging, autophagy and chronic inflammation. They are metabolized to pro- and anti-inflammatory metabolites by various enzymes. These metabolites stimulate inflammation in response to oxidative stress, causing innate and acquired immune responses. This review also discusses the possible clinical applications, which provided novel targets for the prevention and treatment of AMD and other age-related diseases.
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Affiliation(s)
- Jiangbo Ren
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China
- Department of Ophthalmology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China
| | - Anli Ren
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China
- Department of Ophthalmology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China
| | - Xizhi Deng
- Department of Ophthalmology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China
| | - Zhengrong Huang
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China
| | - Ziyu Jiang
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China
| | - Zhi Li
- Department of Ophthalmology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China
| | - Yan Gong
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China
- Human Genetics Resource Preservation Center of Wuhan University, Wuhan University, Wuhan, Hubei, People’s Republic of China
- Correspondence: Yan Gong; Zhi Li, Tel +86 27 6781 1461; +86 27 6781 2622, Fax +86 27 6781 1471; +86 27 6781 3133, Email ;
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13
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Yao F, Zhang X, Yao X, Ren X, Xia X, Jiang J, Ding L. Peroxisome Proliferator-Activated Receptor α Activation Protects Retinal Ganglion Cells in Ischemia-Reperfusion Retinas. Front Med (Lausanne) 2022; 8:788663. [PMID: 35004756 PMCID: PMC8732875 DOI: 10.3389/fmed.2021.788663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 11/24/2021] [Indexed: 01/04/2023] Open
Abstract
Background and Objective: Retinal ischemia-reperfusion (IR) leads to massive loss of retinal ganglion cells (RGC) and characterizes several blind-causing ophthalmic diseases. However, the mechanism related to retinal IR is controversial, and a drug that could prevent the RGC loss caused by IR is still lacking. This study aimed to investigate the role of endogenous retinal peroxisome proliferator-activated receptor (PPAR)α and the therapeutic effect of its agonist, fenofibric acid (FA), in IR-related retinopathy. Materials and Methods: Fenofibric acid treatment was applied to the Sprague-Dawley rats with IR and retinal cell line 28 cells with oxygen-glucose deprivation (OGD) (an in vitro model of IR). Western blotting, real-time PCR, and immunofluorescence were used to examine the expression levels of PPARα, glial fibrillary acidic protein (GFAP), and cyclooxygenase-2 (COX2). Hematoxylin and eosin (HE) staining, propidium iodide (PI) staining, retrograde tracing, and flash visual-evoked potential (FVEP) were applied to assess RGC injury and visual function. Results: Retinal IR down-regulated PPARα expression in vitro and in vivo. Peroxisome proliferator-activated receptor α activation by FA promoted survival of RGCs, mitigated thinning of the ganglion cell complex, and decreased the latency of positive waves of FVEPs after IR injury. Further, FA treatment enhanced the expression of endogenous PPARα and suppressed the expression of GFAP and COX2 significantly. Conclusion: Peroxisome proliferator-activated receptor α activation by FA is protective against RGC loss in retinal IR condition, which may occur by restoring PPARα expression, inhibiting activation of glial cells, and suppressing retinal inflammation. All these findings indicate the translational potential of FA in treating IR-related retinopathy.
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Affiliation(s)
- Fei Yao
- Eye Center of Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Ophthalmology, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China
| | - Xuan Zhang
- Eye Center of Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Ophthalmology, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China
| | - Xueyan Yao
- Eye Center of Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Ophthalmology, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China
| | - Xiaohua Ren
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China.,Department of Human Resource, Xiangya Hospital, Central South University, Changsha, China
| | - Xiaobo Xia
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China.,Department of Human Resource, Xiangya Hospital, Central South University, Changsha, China
| | - Jian Jiang
- Eye Center of Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Ophthalmology, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China
| | - Lexi Ding
- Eye Center of Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Ophthalmology, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China
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14
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Lewandowski D, Sander CL, Tworak A, Gao F, Xu Q, Skowronska-Krawczyk D. Dynamic lipid turnover in photoreceptors and retinal pigment epithelium throughout life. Prog Retin Eye Res 2021; 89:101037. [PMID: 34971765 PMCID: PMC10361839 DOI: 10.1016/j.preteyeres.2021.101037] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 12/13/2022]
Abstract
The retinal pigment epithelium-photoreceptor interphase is renewed each day in a stunning display of cellular interdependence. While photoreceptors use photosensitive pigments to convert light into electrical signals, the RPE supports photoreceptors in their function by phagocytizing shed photoreceptor tips, regulating the blood retina barrier, and modulating inflammatory responses, as well as regenerating the 11-cis-retinal chromophore via the classical visual cycle. These processes involve multiple protein complexes, tightly regulated ligand-receptors interactions, and a plethora of lipids and protein-lipids interactions. The role of lipids in maintaining a healthy interplay between the RPE and photoreceptors has not been fully delineated. In recent years, novel technologies have resulted in major advancements in understanding several facets of this interplay, including the involvement of lipids in phagocytosis and phagolysosome function, nutrient recycling, and the metabolic dependence between the two cell types. In this review, we aim to integrate the complex role of lipids in photoreceptor and RPE function, emphasizing the dynamic exchange between the cells as well as discuss how these processes are affected in aging and retinal diseases.
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Affiliation(s)
- Dominik Lewandowski
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Christopher L Sander
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Aleksander Tworak
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Fangyuan Gao
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Qianlan Xu
- Department of Physiology and Biophysics, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Dorota Skowronska-Krawczyk
- Department of Physiology and Biophysics, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA.
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15
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cGMP-PKG dependent transcriptome in normal and degenerating retinas: Novel insights into the retinitis pigmentosa pathology. Exp Eye Res 2021; 212:108752. [PMID: 34478738 DOI: 10.1016/j.exer.2021.108752] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 06/25/2021] [Accepted: 08/25/2021] [Indexed: 12/26/2022]
Abstract
Retinitis Pigmentosa represents a group of genetic disorders that cause progressive vision loss via degeneration of photoreceptors, but there is in principle no treatment available. For any therapy development, a deeper comprehension of the disease-leading mechanism(s) at the molecular level is needed. Here we focused on the cGMP-PKG system, which has been suggested to be a driver in several models of the disease. To gain insights in its downstream signaling we manipulated the cGMP-PKG system with the aid of organotypic retinal explant cultures from either a mouse-based disease model, i.e. the rd1 mouse, or its healthy wild-type counterpart (wt), by adding different types of cGMP analogues to either inhibit or activate PKG in retinal explants from rd1 and wt, respectively. An RNA sequencing was then performed to study the cGMP-PKG dependent transcriptome. Expression changes of gene sets related to specific pathways or functions, that fulfilled criteria involving that the changes should match PKG activation and inhibition, were determined via bioinformatics. The analyses highlighted that several gene sets linked to oxidative phosphorylation and mitochondrial pathways were regulated by this enzyme system. Specifically, the expression of such pathway components was upregulated in the rd1 treated with PKG inhibitor and downregulated in the wt with PKG activator treatment, suggesting that cGMP-PKG act as a negative regulator in this context. Downregulation of energy production pathways may thus play an integral part in the mechanism behind the degeneration for at least several RP mutations.
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16
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Escandon P, Vasini B, Whelchel AE, Nicholas SE, Matlock HG, Ma JX, Karamichos D. The role of peroxisome proliferator-activated receptors in healthy and diseased eyes. Exp Eye Res 2021; 208:108617. [PMID: 34010603 PMCID: PMC8594540 DOI: 10.1016/j.exer.2021.108617] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 12/23/2022]
Abstract
Peroxisome Proliferator-Activated Receptors (PPARs) are a family of nuclear receptors that play essential roles in modulating cell differentiation, inflammation, and metabolism. Three subtypes of PPARs are known: PPAR-alpha (PPARα), PPAR-gamma (PPARγ), and PPAR-beta/delta (PPARβ/δ). PPARα activation reduces lipid levels and regulates energy homeostasis, activation of PPARγ results in regulation of adipogenesis, and PPARβ/δ activation increases fatty acid metabolism and lipolysis. PPARs are linked to various diseases, including but not limited to diabetes, non-alcoholic fatty liver disease, glaucoma and atherosclerosis. In the past decade, numerous studies have assessed the functional properties of PPARs in the eye and key PPAR mechanisms have been discovered, particularly regarding the retina and cornea. PPARγ and PPARα are well established in their functions in ocular homeostasis regarding neuroprotection, neovascularization, and inflammation, whereas PPARβ/δ isoform function remains understudied. Naturally, studies on PPAR agonists and antagonists, associated with ocular pathology, have also gained traction with the development of PPAR synthetic ligands. Studies on PPARs has significantly influenced novel therapeutics for diabetic eye disease, ocular neuropathy, dry eye, and age-related macular degeneration (AMD). In this review, therapeutic potentials and implications will be highlighted, as well as reported adverse effects. Further investigations are necessary before any of the PPARs ligands can be utilized, in the clinics, to treat eye diseases. Future research on the prominent role of PPARs will help unravel the complex mechanisms involved in order to prevent and treat ocular diseases.
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Affiliation(s)
- Paulina Escandon
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Brenda Vasini
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Amy E Whelchel
- Department of Physiology, University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA
| | - Sarah E Nicholas
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - H Greg Matlock
- Department of Physiology, University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA
| | - Jian-Xing Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA; Harold Hamm Oklahoma Diabetes Center, 1000 N Lincoln Blvd, Oklahoma City, OK, USA
| | - Dimitrios Karamichos
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA.
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17
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Burger CA, Jiang D, Mackin RD, Samuel MA. Development and maintenance of vision's first synapse. Dev Biol 2021; 476:218-239. [PMID: 33848537 DOI: 10.1016/j.ydbio.2021.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/02/2021] [Accepted: 04/03/2021] [Indexed: 12/21/2022]
Abstract
Synapses in the outer retina are the first information relay points in vision. Here, photoreceptors form synapses onto two types of interneurons, bipolar cells and horizontal cells. Because outer retina synapses are particularly large and highly ordered, they have been a useful system for the discovery of mechanisms underlying synapse specificity and maintenance. Understanding these processes is critical to efforts aimed at restoring visual function through repairing or replacing neurons and promoting their connectivity. We review outer retina neuron synapse architecture, neural migration modes, and the cellular and molecular pathways that play key roles in the development and maintenance of these connections. We further discuss how these mechanisms may impact connectivity in the retina.
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Affiliation(s)
- Courtney A Burger
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Danye Jiang
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Robert D Mackin
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Melanie A Samuel
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA.
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18
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Photoreceptor metabolic reprogramming: current understanding and therapeutic implications. Commun Biol 2021; 4:245. [PMID: 33627778 PMCID: PMC7904922 DOI: 10.1038/s42003-021-01765-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 01/28/2021] [Indexed: 02/06/2023] Open
Abstract
Acquired and inherited retinal disorders are responsible for vision loss in an increasing proportion of individuals worldwide. Photoreceptor (PR) death is central to the vision loss individuals experience in these various retinal diseases. Unfortunately, there is a lack of treatment options to prevent PR loss, so an urgent unmet need exists for therapies that improve PR survival and ultimately, vision. The retina is one of the most energy demanding tissues in the body, and this is driven in large part by the metabolic needs of PRs. Recent studies suggest that disruption of nutrient availability and regulation of cell metabolism may be a unifying mechanism in PR death. Understanding retinal cell metabolism and how it is altered in disease has been identified as a priority area of research. The focus of this review is on the recent advances in the understanding of PR metabolism and how it is critical to reduction-oxidation (redox) balance, the outer retinal metabolic ecosystem, and retinal disease. The importance of these metabolic processes is just beginning to be realized and unraveling the metabolic and redox pathways integral to PR health may identify novel targets for neuroprotective strategies that prevent blindness in the heterogenous group of retinal disorders.
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19
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Fu Z, Kern TS, Hellström A, Smith LEH. Fatty acid oxidation and photoreceptor metabolic needs. J Lipid Res 2021; 62:100035. [PMID: 32094231 PMCID: PMC7905050 DOI: 10.1194/jlr.tr120000618] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/14/2020] [Indexed: 01/31/2023] Open
Abstract
Photoreceptors have high energy demands and a high density of mitochondria that produce ATP through oxidative phosphorylation (OXPHOS) of fuel substrates. Although glucose is the major fuel for CNS brain neurons, in photoreceptors (also CNS), most glucose is not metabolized through OXPHOS but is instead metabolized into lactate by aerobic glycolysis. The major fuel sources for photoreceptor mitochondria remained unclear for almost six decades. Similar to other tissues (like heart and skeletal muscle) with high metabolic rates, photoreceptors were recently found to metabolize fatty acids (palmitate) through OXPHOS. Disruption of lipid entry into photoreceptors leads to extracellular lipid accumulation, suppressed glucose transporter expression, and a duel lipid/glucose fuel shortage. Modulation of lipid metabolism helps restore photoreceptor function. However, further elucidation of the types of lipids used as retinal energy sources, the metabolic interaction with other fuel pathways, as well as the cross-talk among retinal cells to provide energy to photoreceptors is not fully understood. In this review, we will focus on the current understanding of photoreceptor energy demand and sources, and potential future investigations of photoreceptor metabolism.
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Affiliation(s)
- Zhongjie Fu
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Manton Center for Orphan Disease, Boston Children's Hospital, Boston, MA, USA.
| | - Timothy S Kern
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Irvine, CA, USA
| | - Ann Hellström
- Section for Ophthalmology, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| | - Lois E H Smith
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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20
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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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21
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Enright JM, Zhang S, Thebeau C, Siebert E, Jin A, Gadiraju V, Zhang X, Chen S, Semenkovich CF, Rajagopal R. Fenofibrate Reduces the Severity of Neuroretinopathy in a Type 2 Model of Diabetes without Inducing Peroxisome Proliferator-Activated Receptor Alpha-Dependent Retinal Gene Expression. J Clin Med 2020; 10:jcm10010126. [PMID: 33396512 PMCID: PMC7794763 DOI: 10.3390/jcm10010126] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/27/2020] [Accepted: 12/09/2020] [Indexed: 12/11/2022] Open
Abstract
Fenofibrate slows the progression of clinical diabetic retinopathy (DR), but its mechanism of action in the retina remains unclear. Fenofibrate is a known agonist of peroxisome proliferator-activated receptor alpha (PPARα), a transcription factor critical for regulating metabolism, inflammation and oxidative stress. Using a DR mouse model, db/db, we tested the hypothesis that fenofibrate slows early DR progression by activating PPARα in the retina. Relative to healthy littermates, six-month-old db/db mice exhibited elevated serum triglycerides and cholesterol, retinal gliosis, and electroretinography (ERG) changes including reduced b-wave amplitudes and delayed oscillatory potentials. These pathologic changes in the retina were improved by oral fenofibrate. However, fenofibrate did not induce PPARα target gene expression in whole retina or isolated Müller glia. The capacity of the retina to respond to PPARα was further tested by delivering the PPARα agonist GW590735 to the intraperitoneal or intravitreous space in mice carrying the peroxisome proliferator response element (PPRE)-luciferase reporter. We observed strong induction of the reporter in the liver, but no induction in the retina. In summary, fenofibrate treatment of db/db mice prevents the development of early DR but is not associated with induction of PPARα in the retina.
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Affiliation(s)
- Jennifer M. Enright
- John F. Hardesty Department of Ophthalmology, Washington University in St. Louis, St. Louis, MO 63110, USA; (J.M.E.); (S.Z.); (C.T.); (X.Z.); (S.C.)
| | - Sheng Zhang
- John F. Hardesty Department of Ophthalmology, Washington University in St. Louis, St. Louis, MO 63110, USA; (J.M.E.); (S.Z.); (C.T.); (X.Z.); (S.C.)
| | - Christina Thebeau
- John F. Hardesty Department of Ophthalmology, Washington University in St. Louis, St. Louis, MO 63110, USA; (J.M.E.); (S.Z.); (C.T.); (X.Z.); (S.C.)
| | - Emily Siebert
- Department of Pediatrics, UT Southwestern Medical Center, Dallas, TX 75390, USA;
| | - Alexander Jin
- St. Louis University School of Medicine, St. Louis, MO 63104, USA;
| | - Veda Gadiraju
- University of Washington Medical School, Seattle, WA 98195, USA;
| | - Xiaodong Zhang
- John F. Hardesty Department of Ophthalmology, Washington University in St. Louis, St. Louis, MO 63110, USA; (J.M.E.); (S.Z.); (C.T.); (X.Z.); (S.C.)
| | - Shiming Chen
- John F. Hardesty Department of Ophthalmology, Washington University in St. Louis, St. Louis, MO 63110, USA; (J.M.E.); (S.Z.); (C.T.); (X.Z.); (S.C.)
| | - Clay F. Semenkovich
- Division of Endocrinology, Metabolism and Lipid Research, Washington University in St. Louis, St. Louis, MO 63110, USA;
| | - Rithwick Rajagopal
- John F. Hardesty Department of Ophthalmology, Washington University in St. Louis, St. Louis, MO 63110, USA; (J.M.E.); (S.Z.); (C.T.); (X.Z.); (S.C.)
- Correspondence:
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22
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PPAR α Agonist WY-14643 Relieves Neuropathic Pain through SIRT1-Mediated Deacetylation of NF- κB. PPAR Res 2020; 2020:6661642. [PMID: 33414819 PMCID: PMC7752300 DOI: 10.1155/2020/6661642] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/09/2020] [Accepted: 11/23/2020] [Indexed: 01/04/2023] Open
Abstract
Inflammation caused by neuropathy contributes to the development of neuropathic pain (NP), but the exact mechanism still needs to be understood. Peroxisome proliferator-activated receptor α (PPARα), an important inflammation regulator, might participate in the inflammation in NP. To explore the role of PPARα in NP, the effects of PPARα agonist WY-14643 on chronic constriction injury (CCI) rats were evaluated. The results showed that WY-14643 stimulation could decrease inflammation and relieve neuropathic pain, which was relative with the activation of PPARα. In addition, we also found that the SIRT1/NF-κB pathway was involved in the WY-14643-induced anti-inflammation in NP, and activation of PPARα increased SIRT1 expression, thus reducing the proinflammatory function of NF-κB. These data suggested that WY-14643 might serve as an inflammation mediator, which may be a potential therapy option for NP.
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23
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Chen Q, Jiang N, Zhang Y, Ye S, Liang X, Wang X, Lin X, Zong R, Chen H, Liu Z. Fenofibrate Inhibits Subretinal Fibrosis Through Suppressing TGF-β-Smad2/3 signaling and Wnt signaling in Neovascular Age-Related Macular Degeneration. Front Pharmacol 2020; 11:580884. [PMID: 33442383 PMCID: PMC7797782 DOI: 10.3389/fphar.2020.580884] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/13/2020] [Indexed: 12/29/2022] Open
Abstract
Subretinal fibrosis is a common pathological change that causes vision loss in neovascular age-related macular degeneration (nAMD). Treatment modalities for subretinal fibrosis are limited. In the present study, the effects of fenofibrate, a specific peroxisome proliferator-activated receptor alpha agonist, on subretinal fibrosis of nAMD were tested, and its molecular mechanisms of action were delineated. Collagen deposition and protein expression of fibrotic markers, such as vimentin, collagen-1, alpha-smooth muscle actin, and fibronectin, were increased in very low-density lipoprotein receptor (VLDLR) knockout mouse, indicating Vldlr -/- mice can be used as a model for subretinal fibrosis. Fenofibrate suppressed subretinal fibrosis of Vldlr -/- mice by reducing collagen deposition and protein expression of fibrotic markers. Two fibrotic pathways, TGF-β-Smad2/3 signaling and Wnt signaling, were significantly up-regulated, while inhibited by fenofibrate in Vldlr -/- retinas. Moreover, fenofibrate significantly reduced the downstream connective tissue growth factor (CTGF) expression of these two pathways. Müller cells were a major source of CTGF in Vldlr -/- retinas. Fenofibrate was capable of suppressing Müller cell activation and thus reducing the release of CTGF in Vldlr -/- retinas. In cultured Müller cells, fenofibrate reversed TGF-β2-induced up-regulation of Wnt signaling and CTGF expression. These findings suggested that fenofibrate inhibits subretinal fibrosis by suppressing TGF-β-Smad2/3 signaling and Wnt signaling and reducing CTGF expression, and thus, fenofibrate could be a potential treatment for nAMD with subretinal fibrosis.
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Affiliation(s)
- Qian Chen
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, China.,Xiamen University affiliated Xiamen Eye Center, Xiamen, China
| | - Nan Jiang
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Yuhan Zhang
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Sihao Ye
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Xu Liang
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Xin Wang
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Xiang Lin
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Rongrong Zong
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Haoyu Chen
- Joint Shantou International Eye Center of Shantou University and the Chinese University of Hong Kong, Shantou, China
| | - Zuguo Liu
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Eye Institute of Xiamen University, School of Medicine, Xiamen University, Xiamen, China.,Xiamen University affiliated Xiamen Eye Center, Xiamen, China
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24
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Fenofibrate prevents iron induced activation of canonical Wnt/β-catenin and oxidative stress signaling in the retina. NPJ Aging Mech Dis 2020; 6:12. [PMID: 33145027 PMCID: PMC7599211 DOI: 10.1038/s41514-020-00050-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 10/09/2020] [Indexed: 12/20/2022] Open
Abstract
Accumulating evidence strongly implicates iron in the pathogenesis of aging and disease. Iron levels have been found to increase with age in both the human and mouse retinas. We and others have shown that retinal diseases such as age-related macular degeneration and diabetic retinopathy are associated with disrupted iron homeostasis, resulting in retinal iron accumulation. In addition, hereditary disorders due to mutation in one of the iron regulatory genes lead to age dependent retinal iron overload and degeneration. However, our knowledge on whether iron toxicity contributes to the retinopathy is limited. Recently, we reported that iron accumulation is associated with the upregulation of retinal and renal renin-angiotensin system (RAS). Evidences indicate that multiple genes/components of the RAS are targets of Wnt/β-catenin signaling. Interestingly, aberrant activation of Wnt/β-catenin signaling is observed in several degenerative diseases. In the present study, we explored whether iron accumulation regulates canonical Wnt signaling in the retina. We found that in vitro and in vivo iron treatment resulted in the upregulation of Wnt/β-catenin signaling and its downstream target genes including renin-angiotensin system in the retina. We confirmed further that iron activates canonical Wnt signaling in the retina using TOPFlash T-cell factor/lymphoid enhancer factor promoter assay and Axin2-LacZ reporter mouse. The presence of an iron chelator or an antioxidant reversed the iron-mediated upregulation of Wnt/β-catenin signaling in retinal pigment epithelial (RPE) cells. In addition, treatment of RPE cells with peroxisome proliferator-activated receptor (PPAR) α-agonist fenofibrate prevented iron-induced activation of oxidative stress and Wnt/β-catenin signaling by chelating the iron. The role of fenofibrate, an FDA-approved drug for hyperlipidemia, as an iron chelator has potentially significant therapeutic impact on iron associated degenerative diseases.
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25
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Abstract
This review focuses on recent progress in understanding the role of mitochondrial markers in the context of mitochondrial dysfunction in glaucoma and discussing new therapeutic approaches to modulate mitochondrial function and potentially lead to improved outcomes in glaucoma.
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26
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Xu L, Brown EE, Santiago CP, Keuthan CJ, Lobanova E, Ash JD. Retinal homeostasis and metformin-induced protection are not affected by retina-specific Pparδ knockout. Redox Biol 2020; 37:101700. [PMID: 32863184 PMCID: PMC7767733 DOI: 10.1016/j.redox.2020.101700] [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: 06/23/2020] [Revised: 08/08/2020] [Accepted: 08/19/2020] [Indexed: 11/25/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are a family of three nuclear hormone receptors (PPARα, PPARδ, and PPARγ) that are known to regulate expression of lipid metabolism and oxidative stress genes. Given their role in reducing oxidative stress in a variety of tissues, these genes are likely important for retinal homeostasis. This hypothesis has been further supported by recent studies suggesting that PPAR-activating drugs are protective against retinal degenerations. The objective of the present study was to determine the role of PPARδ in the neuroretina. RNA-seq data show that Pparα and Pparδ are both expressed in the retina, but that Pparδ is expressed at 4-fold higher levels. Single-cell RNAseq data show that Pparδ is broadly expressed in all retinal cell types. To determine the importance of Pparδ to the retina, we generated retina-specific Pparδ knockout mice. We found that deletion of Pparδ had a minimal effect on retinal function or morphology out to 12 months of age and did not increase retinal sensitivity to oxidative stress induced by exposure to bright light. While data show that PPARδ levels were increased by the drug metformin, PPARδ was not necessary for metformin-induced protection from light damage. These data suggest that Pparδ either has a redundant function with Pparα or is not essential for normal neuroretina function or resistance to oxidative stress. PPARδ is not essential for neuroretinal development or retinal structure or function. Deletion of PPARδ in the neuroretina does not enhance degeneration due to light-induced damage. Metformin-induced neuroprotection is not mediated by PPARδ activity.
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Affiliation(s)
- Lei Xu
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Emily E Brown
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Clayton P Santiago
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Casey J Keuthan
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Ekaterina Lobanova
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, FL, USA; Department of Molecular Genetics & Microbiology, College of Medicine, University of Florida, 32610, USA; Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, 32610, USA
| | - John D Ash
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, FL, USA.
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27
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Dou X, Nath D, Shin H, Nurmemmedov E, Bourne PC, Ma JX, Duerfeldt AS. Evolution of a 4-Benzyloxy-benzylamino Chemotype to Provide Efficacious, Potent, and Isoform Selective PPARα Agonists as Leads for Retinal Disorders. J Med Chem 2020; 63:2854-2876. [PMID: 32096640 DOI: 10.1021/acs.jmedchem.9b01189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Peroxisome proliferator-activated receptor alpha (PPARα) is expressed in retinal Müller cells, endothelial cells, and in retinal pigment epithelium; agonism of PPARα with genetic or pharmacological tools ameliorates inflammation, vascular leakage, neurodegeneration, and neovascularization associated with retinal diseases in animal models. As such, PPARα is a promising drug target for diabetic retinopathy and age-related macular degeneration. Herein, we report proof-of-concept in vivo efficacy in an streptozotocin-induced vascular leakage model (rat) and preliminary pharmacokinetic assessment of a first-generation lead 4a (A91). Additionally, we present the design, synthesis, and evaluation of second-generation analogues, which led to the discovery of 4u and related compounds that reach cellular potencies <50 nM and exhibit >2,700-fold selectivity for PPARα over other PPAR isoforms. These studies identify a pipeline of candidates positioned for detailed PK/PD and pre-clinical evaluation.
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Affiliation(s)
- Xiaozheng Dou
- Institute for Natural Products Applications and Research Technologies, University of Oklahoma, 101 Stephenson Parkway, Stephenson Life Sciences Research Center, Norman, Oklahoma 73019, United States.,Department of Chemistry & Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Stephenson Life Sciences Research Center, Norman, Oklahoma 73019, United States
| | - Dinesh Nath
- Institute for Natural Products Applications and Research Technologies, University of Oklahoma, 101 Stephenson Parkway, Stephenson Life Sciences Research Center, Norman, Oklahoma 73019, United States.,Department of Chemistry & Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Stephenson Life Sciences Research Center, Norman, Oklahoma 73019, United States
| | - Henry Shin
- Department of Physiology, University of Oklahoma Health Sciences Center, 941 Stanton L. Young Boulevard, Oklahoma City, Oklahoma 73104, United States
| | - Elmar Nurmemmedov
- John Wayne Cancer Institute & Pacific Neuroscience Institute at Providence Saint John's Health Center, 2200 Santa Monica Boulevard, Santa Monica, California 90404, United States
| | - Philip C Bourne
- Department of Chemistry & Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Stephenson Life Sciences Research Center, Norman, Oklahoma 73019, United States
| | - Jian-Xing Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, 941 Stanton L. Young Boulevard, Oklahoma City, Oklahoma 73104, United States
| | - Adam S Duerfeldt
- Institute for Natural Products Applications and Research Technologies, University of Oklahoma, 101 Stephenson Parkway, Stephenson Life Sciences Research Center, Norman, Oklahoma 73019, United States.,Department of Chemistry & Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Stephenson Life Sciences Research Center, Norman, Oklahoma 73019, United States
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28
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Shao Y, Chen J, Dong LJ, He X, Cheng R, Zhou K, Liu J, Qiu F, Li XR, Ma JX. A Protective Effect of PPARα in Endothelial Progenitor Cells Through Regulating Metabolism. Diabetes 2019; 68:2131-2142. [PMID: 31451517 PMCID: PMC6804623 DOI: 10.2337/db18-1278] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 08/23/2019] [Indexed: 12/12/2022]
Abstract
Deficiency of endothelial progenitor cells, including endothelial colony-forming cells (ECFCs) and circulating angiogenic cells (CACs), plays an important role in retinal vascular degeneration in diabetic retinopathy (DR). Fenofibrate, an agonist of peroxisome proliferator-activated receptor α (PPARα), has shown therapeutic effects on DR in both patients and diabetic animal models. However, the function of PPARα in ECFC/CACs has not been defined. In this study, we determined the regulation of ECFC/CAC by PPARα. As shown by flow cytometry and Seahorse analysis, ECFC/CAC numbers and mitochondrial function were decreased in the bone marrow, circulation, and retina of db/db mice, correlating with PPARα downregulation. Activation of PPARα by fenofibrate normalized ECFC/CAC numbers and mitochondrial function in diabetes. In contrast, PPARα knockout exacerbated ECFC/CAC number decreases and mitochondrial dysfunction in diabetic mice. Primary ECFCs from PPARα -/- mice displayed impaired proliferation, migration, and tube formation. Furthermore, PPARα -/- ECFCs showed reduced mitochondrial oxidation and glycolysis compared with wild type, correlating with decreases of Akt phosphorylation and expression of its downstream genes regulating ECFC fate and metabolism. These findings suggest that PPARα is an endogenous regulator of ECFC/CAC metabolism and cell fate. Diabetes-induced downregulation of PPARα contributes to ECFC/CAC deficiency and retinal vascular degeneration in DR.
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Affiliation(s)
- Yan Shao
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
- Department of Physiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Jianglei Chen
- Department of Physiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Li-Jie Dong
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
- Department of Physiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Xuemin He
- Department of Physiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Rui Cheng
- Department of Physiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Kelu Zhou
- Department of Physiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Juping Liu
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
| | - Fangfang Qiu
- Department of Physiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Xiao-Rong Li
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
- Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China
| | - Jian-Xing Ma
- Department of Physiology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK
- Harold Hamm Diabetes Center, The University of Oklahoma Health Sciences Center, Oklahoma City, OK
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29
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Fu Z, Chen CT, Cagnone G, Heckel E, Sun Y, Cakir B, Tomita Y, Huang S, Li Q, Britton W, Cho SS, Kern TS, Hellström A, Joyal JS, Smith LE. Dyslipidemia in retinal metabolic disorders. EMBO Mol Med 2019; 11:e10473. [PMID: 31486227 PMCID: PMC6783651 DOI: 10.15252/emmm.201910473] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 06/10/2019] [Accepted: 08/15/2019] [Indexed: 12/24/2022] Open
Abstract
The light‐sensitive photoreceptors in the retina are extremely metabolically demanding and have the highest density of mitochondria of any cell in the body. Both physiological and pathological retinal vascular growth and regression are controlled by photoreceptor energy demands. It is critical to understand the energy demands of photoreceptors and fuel sources supplying them to understand neurovascular diseases. Retinas are very rich in lipids, which are continuously recycled as lipid‐rich photoreceptor outer segments are shed and reformed and dietary intake of lipids modulates retinal lipid composition. Lipids (as well as glucose) are fuel substrates for photoreceptor mitochondria. Dyslipidemia contributes to the development and progression of retinal dysfunction in many eye diseases. Here, we review photoreceptor energy demands with a focus on lipid metabolism in retinal neurovascular disorders.
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Affiliation(s)
- Zhongjie Fu
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA.,Manton Center for Orphan Disease, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Chuck T Chen
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Gael Cagnone
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, QC, Canada.,Department of Pharmacology and Therapeutics, University of Montreal, Montreal, QC, Canada
| | - Emilie Heckel
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, QC, Canada.,Department of Pharmacology and Therapeutics, University of Montreal, Montreal, QC, Canada
| | - Ye Sun
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Bertan Cakir
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Yohei Tomita
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Shuo Huang
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Qian Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - William Britton
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Steve S Cho
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Timothy S Kern
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Irvine, CA, USA
| | - Ann Hellström
- Section for Ophthalmology, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| | - Jean-Sébastien Joyal
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, QC, Canada.,Department of Pharmacology and Therapeutics, University of Montreal, Montreal, QC, Canada
| | - Lois Eh Smith
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
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30
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Nashine S, Subramaniam SR, Chwa M, Nesburn A, Kuppermann BD, Federoff H, Kenney MC. PU-91 drug rescues human age-related macular degeneration RPE cells; implications for AMD therapeutics. Aging (Albany NY) 2019; 11:6691-6713. [PMID: 31477635 PMCID: PMC6756897 DOI: 10.18632/aging.102179] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 08/09/2019] [Indexed: 12/24/2022]
Abstract
Since mitochondrial dysfunction is implicated in the pathogenesis of AMD, this study is based on the premise that repurposing of mitochondria-stabilizing FDA-approved drugs such as PU-91, might rescue AMD RPE cells from AMD mitochondria-induced damage. The PU-91 drug upregulates PGC-1α which is a critical regulator of mitochondrial biogenesis. Herein, we tested the therapeutic potential of PU-91 drug and examined the additive effects of treatment with PU-91 and esterase inhibitors i.e., EI-12 and EI-78, using the in vitro transmitochondrial AMD cell model. This model was created by fusing platelets obtained from AMD patients with Rho0 i.e., mitochondria-deficient, ARPE-19 cell lines. The resulting AMD RPE cell lines have identical nuclei but differ in their mitochondrial DNA content, which is derived from individual AMD patients. Briefly, we report significant improvement in cell survival, mitochondrial health, and antioxidant potential in PU-91-treated AMD RPE cells compared to their untreated counterparts. In conclusion, this study identifies PU 91 as a therapeutic candidate drug for AMD and repurposing of PU-91 will be a smoother transition from lab bench to clinic since the pharmacological profiles of PU-91 have been examined already.
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Affiliation(s)
- Sonali Nashine
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92697, USA
| | | | - Marilyn Chwa
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92697, USA
| | - Anthony Nesburn
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92697, USA.,Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Baruch D Kuppermann
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92697, USA
| | - Howard Federoff
- Department of Neurology, University of California Irvine, Irvine, CA 92697, USA
| | - M Cristina Kenney
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92697, USA.,Department of Pathology and Laboratory Medicine, University of California Irvine, Irvine, CA 92697, USA
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31
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Transcriptome Analysis Reveals the Effect of Long Intergenic Noncoding RNAs on Pig Muscle Growth and Fat Deposition. BIOMED RESEARCH INTERNATIONAL 2019; 2019:2951427. [PMID: 31341893 PMCID: PMC6614983 DOI: 10.1155/2019/2951427] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 06/01/2019] [Indexed: 01/09/2023]
Abstract
Muscle growth and fat deposition are the two important biological processes in the development of pigs which are closely related to the pig production performance. Long intergenic noncoding RNAs (lincRNAs), with lack of coding potential and the length of at least 200nt, have been extensively studied to play important roles in many biological processes. However, the importance and molecular regulation mechanism of lincRNAs in the process of muscle growth and fat deposition in pigs are still to be further studied comprehensively. In our study, we used the data, including liver, abdominal fat, and longissimus dorsi muscle of 240 days' age of two F2 full-sib female individuals from the white Duroc and Erhualian crossbreed, to identify 581 putative lincRNAs associated with pig muscle growth and fat deposition. The 581 putative lincRNAs shared many common features with other mammalian lincRNAs, such as fewer exons, lower expression levels, and shorter transcript lengths. Cross-tissue comparisons showed that many transcripts were tissue-specific and were involved in the important biological processes in their corresponding tissues. Gene ontology and pathway analysis revealed that many potential target genes (PTGs) of putative lincRNAs were involved in pig muscle growth and fat deposition-related processes, including muscle cell proliferation, lipid metabolism, and fatty acid degradation. In Quantitative Trait Locus (QTLs) analysis, some PTGs were screened from putative lincRNAs, MRPL12 is associated with muscle growth, GCGR and SLC25A10 were associated with fat deposition, and PPP3CA, DPYD, and FGGY were related not only to muscle growth but also to fat deposition. Therefore, it implied that these lincRNAs might participate in the biological processes related to muscle growth or fat deposition through homeostatic regulation of PTGs, but the detailed molecular regulatory mechanisms still needed to be further explored. This study lays the molecular foundation for the in-depth study of the role of lincRNAs in the pig muscle growth and fat deposition and further provides the new molecular markers for understanding the complex biological mechanisms of pig muscle growth and fat deposition.
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32
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Pearsall EA, Cheng R, Matsuzaki S, Zhou K, Ding L, Ahn B, Kinter M, Humphries KM, Quiambao AB, Farjo RA, Ma JX. Neuroprotective effects of PPARα in retinopathy of type 1 diabetes. PLoS One 2019; 14:e0208399. [PMID: 30716067 PMCID: PMC6361421 DOI: 10.1371/journal.pone.0208399] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 11/16/2018] [Indexed: 01/01/2023] Open
Abstract
Diabetic retinopathy (DR) is a common neurovascular complication of type 1 diabetes. Current therapeutics target neovascularization characteristic of end-stage disease, but are associated with significant adverse effects. Targeting early events of DR such as neurodegeneration may lead to safer and more effective approaches to treatment. Two independent prospective clinical trials unexpectedly identified that the PPARα agonist fenofibrate had unprecedented therapeutic effects in DR, but gave little insight into the physiological and molecular mechanisms of action. The objective of the present study was to evaluate potential neuroprotective effects of PPARα in DR, and subsequently to identify the responsible mechanism of action. Here we reveal that activation of PPARα had a robust protective effect on retinal function as shown by Optokinetic tracking in a rat model of type 1 diabetes, and also decreased retinal cell death, as demonstrated by a DNA fragmentation ELISA. Further, PPARα ablation exacerbated diabetes-induced decline of visual function as demonstrated by ERG analysis. We further found that PPARα improved mitochondrial efficiency in DR, and decreased ROS production and cell death in cultured retinal neurons. Oxidative stress biomarkers were elevated in diabetic Pparα-/- mice, suggesting increased oxidative stress. Mitochondrially mediated apoptosis and oxidative stress secondary to mitochondrial dysfunction contribute to neurodegeneration in DR. Taken together, these findings identify a robust neuroprotective effect for PPARα in DR, which may be due to improved mitochondrial function and subsequent alleviation of energetic deficits, oxidative stress and mitochondrially mediated apoptosis.
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Affiliation(s)
- Elizabeth A. Pearsall
- Angiogenesis Laboratory, Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, United States
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Rui Cheng
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Satoshi Matsuzaki
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
| | - Kelu Zhou
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Lexi Ding
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Bumsoo Ahn
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
| | - Michael Kinter
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
| | - Kenneth M. Humphries
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
- Department of Biochemistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | | | | | - Jian-xing Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
- Harold Hamm Oklahoma Diabetes Center, Oklahoma City, OK, United States
- * E-mail:
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33
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Abstract
Each day, the retina converts an immense number of photons into chemical signals that are then transported to higher order neural centers for interpretation. This process of photo transduction requires large quantities of cellular energy and anabolic precursors, making the retina one of the most metabolically active tissues in the body. With such a large metabolic demand, the retina is understandably sensitive to perturbations in perfusion and hypoxia. Indeed, retinal ischemia underlies many prevalent retinal disorders including diabetic retinopathy (DR), retinal vein occlusion (RVO), and retinopathy of prematurity (ROP). Retinal ischemia leads to the expression of growth factors, cytokines, and other cellular mediators which promote inflammation, vascular dysfunction, and ultimately, vision loss. This review aims to highlight the most recent and compelling findings that have advanced our understanding of the molecular mechanisms underlying retinal ischemias.
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Affiliation(s)
- Seth D Fortmann
- Department of Ophthalmology, University of Alabama, Birmingham, AL, United States
| | - Maria B Grant
- Department of Ophthalmology, University of Alabama, Birmingham, AL, United States
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34
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Millman JR, Doggett T, Thebeau C, Zhang S, Semenkovich CF, Rajagopal R. Measurement of Energy Metabolism in Explanted Retinal Tissue Using Extracellular Flux Analysis. J Vis Exp 2019. [PMID: 30663677 DOI: 10.3791/58626] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
High acuity vision is a heavily energy-consuming process, and the retina has developed several unique adaptations to precisely meet such demands while maintaining transparency of the visual axis. Perturbations to this delicate balance cause blinding illnesses, such as diabetic retinopathy. Therefore, the understanding of energy metabolism changes in the retina during disease is imperative to the development of rational therapies for various causes of vison loss. The recent advent of commercially-available extracellular flux analyzers has made the study of retinal energy metabolism more accessible. This protocol describes the use of such an analyzer to measure contributions to retinal energy supply through its two principle arms - oxidative phosphorylation and glycolysis - by quantifying changes in oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) as proxies for these pathways. This technique is readily performed in explanted retinal tissue, facilitating assessment of responses to multiple pharmacologic agents in a single experiment. Metabolic signatures in retinas from animals lacking rod photoreceptor signaling are compared to wild-type controls using this method. A major limitation in this technique is the lack of ability to discriminate between light-adapted and dark-adapted energy utilization, an important physiologic consideration in retinal tissue.
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Affiliation(s)
- Jeffrey R Millman
- Division of Metabolism, Endocrinology and Lipid Research, Department of Medicine, Washington University School of Medicine; Department of Biomedical Engineering, Washington University in Saint Louis
| | - Teresa Doggett
- Department of Ophthalmology and Visual Science, Washington University School of Medicine
| | - Christina Thebeau
- Department of Ophthalmology and Visual Science, Washington University School of Medicine
| | - Sheng Zhang
- Department of Ophthalmology and Visual Science, Washington University School of Medicine
| | - Clay F Semenkovich
- Division of Metabolism, Endocrinology and Lipid Research, Department of Medicine, Washington University School of Medicine
| | - Rithwick Rajagopal
- Department of Ophthalmology and Visual Science, Washington University School of Medicine;
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35
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Tang L, Wang X, Wu J, Li SM, Zhang Z, Wu S, Su T, Lin Z, Chen X, Liao X, Bai T, Qiu Y, Reinach PS, Li W, Chen Y, Liu Z. Sleep Deprivation Induces Dry Eye Through Inhibition of PPARα Expression in Corneal Epithelium. ACTA ACUST UNITED AC 2018; 59:5494-5508. [DOI: 10.1167/iovs.18-24504] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Liying Tang
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - Xue Wang
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - Jieli Wu
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - San Ming Li
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - Zhaoqiang Zhang
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - Sangang Wu
- Department of Radiation Oncology, Xiamen Cancer Hospital, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, China
| | - Ting Su
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - Zhirong Lin
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
- Xiamen University Affiliated Xiamen Eye Center, Xiamen, Fujian, China
| | - Xueting Chen
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - Xulin Liao
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - Ting Bai
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - Yan Qiu
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | | | - Wei Li
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
- Xiamen University Affiliated Xiamen Eye Center, Xiamen, Fujian, China
- The Affiliated Xiang'an Hospital of Xiamen University, Xiamen, Fujian, China
| | - Yongxiong Chen
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
| | - Zuguo Liu
- Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Medical College, Xiamen University, Xiamen, Fujian, China
- Xiamen University Affiliated Xiamen Eye Center, Xiamen, Fujian, China
- The Affiliated Xiang'an Hospital of Xiamen University, Xiamen, Fujian, China
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36
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Castelli V, d'Angelo M, Antonosante A, Catanesi M, Benedetti E, Desideri G, Cimini A. Physiology and Pathophysiology of PPARs in the Eye. NUCLEAR RECEPTOR RESEARCH 2018. [DOI: 10.11131/2018/101370] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Vanessa Castelli
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | - Michele d'Angelo
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | - Andrea Antonosante
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | - Mariano Catanesi
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | - Elisabetta Benedetti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | | | - Annamaria Cimini
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
- Sbarro Institute for Cancer Research and Molecular Medicine, Department of Biology, Temple University, Philadelphia, USA
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37
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Structural and Functional Rescue of Chronic Metabolically Stressed Optic Nerves through Respiration. J Neurosci 2018; 38:5122-5139. [PMID: 29760184 DOI: 10.1523/jneurosci.3652-17.2018] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 02/27/2018] [Accepted: 04/24/2018] [Indexed: 01/05/2023] Open
Abstract
Axon degeneration can arise from metabolic stress, potentially a result of mitochondrial dysfunction or lack of appropriate substrate input. In this study, we investigated whether the metabolic vulnerability observed during optic neuropathy in the DBA/2J (D2) model of glaucoma is due to dysfunctional mitochondria or impaired substrate delivery to axons, the latter based on our observation of significantly decreased glucose and monocarboxylate transporters in D2 optic nerve (ON), human ON, and mice subjected to acute glaucoma injury. We placed both sexes of D2 mice destined to develop glaucoma and mice of a control strain, the DBA/2J-Gpnmb+, on a ketogenic diet to encourage mitochondrial function. Eight weeks of the diet generated mitochondria, improved energy availability by reversing monocarboxylate transporter decline, reduced glial hypertrophy, protected retinal ganglion cells and their axons from degeneration, and maintained physiological signaling to the brain. A robust antioxidant response also accompanied the response to the diet. These results suggest that energy compromise and subsequent axon degeneration in the D2 is due to low substrate availability secondary to transporter downregulation.SIGNIFICANCE STATEMENT We show axons in glaucomatous optic nerve are energy depleted and exhibit chronic metabolic stress. Underlying the metabolic stress are low levels of glucose and monocarboxylate transporters that compromise axon metabolism by limiting substrate availability. Axonal metabolic decline was reversed by upregulating monocarboxylate transporters as a result of placing the animals on a ketogenic diet. Optic nerve mitochondria responded capably to the oxidative phosphorylation necessitated by the diet and showed increased number. These findings indicate that the source of metabolic challenge can occur upstream of mitochondrial dysfunction. Importantly, the intervention was successful despite the animals being on the cusp of significant glaucoma progression.
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