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Zhang SM, Fan B, Li YL, Zuo ZY, Li GY. Oxidative Stress-Involved Mitophagy of Retinal Pigment Epithelium and Retinal Degenerative Diseases. Cell Mol Neurobiol 2023; 43:3265-3276. [PMID: 37391574 PMCID: PMC10477140 DOI: 10.1007/s10571-023-01383-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/22/2023] [Indexed: 07/02/2023]
Abstract
The retinal pigment epithelium (RPE) is a highly specialized and polarized epithelial cell layer that plays an important role in sustaining the structural and functional integrity of photoreceptors. However, the death of RPE is a common pathological feature in various retinal diseases, especially in age-related macular degeneration (AMD) and diabetic retinopathy (DR). Mitophagy, as a programmed self-degradation of dysfunctional mitochondria, is crucial for maintaining cellular homeostasis and cell survival under stress. RPE contains a high density of mitochondria necessary for it to meet energy demands, so severe stimuli can cause mitochondrial dysfunction and the excess generation of intracellular reactive oxygen species (ROS), which can further trigger oxidative stress-involved mitophagy. In this review, we summarize the classical pathways of oxidative stress-involved mitophagy in RPE and investigate its role in the progression of retinal diseases, aiming to provide a new therapeutic strategy for treating retinal degenerative diseases. The role of mitophagy in AMD and DR. In AMD, excessive ROS production promotes mitophagy in the RPE by activating the Nrf2/p62 pathway, while in DR, ROS may suppress mitophagy by the FOXO3-PINK1/parkin signaling pathway or the TXNIP-mitochondria-lysosome-mediated mitophagy.
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Affiliation(s)
- Si-Ming Zhang
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China
| | - Bin Fan
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China
| | - Yu- Lin Li
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China
| | - Zhao-Yang Zuo
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China
| | - Guang-Yu Li
- Department of Ophthalmology, Second Norman Bethune Hospital of Jilin University, Changchun, 130000, China.
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2
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New insight of metabolomics in ocular diseases in the context of 3P medicine. EPMA J 2023; 14:53-71. [PMID: 36866159 PMCID: PMC9971428 DOI: 10.1007/s13167-023-00313-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/09/2023] [Indexed: 02/19/2023]
Abstract
Metabolomics refers to the high-through untargeted or targeted screening of metabolites in biofluids, cells, and tissues. Metabolome reflects the functional states of cells and organs of an individual, influenced by genes, RNA, proteins, and environment. Metabolomic analyses help to understand the interaction between metabolism and phenotype and reveal biomarkers for diseases. Advanced ocular diseases can lead to vision loss and blindness, reducing patients' quality of life and aggravating socio-economic burden. Contextually, the transition from reactive medicine to the predictive, preventive, and personalized (PPPM / 3P) medicine is needed. Clinicians and researchers dedicate a lot of efforts to explore effective ways for disease prevention, biomarkers for disease prediction, and personalized treatments, by taking advantages of metabolomics. In this way, metabolomics has great clinical utility in the primary and secondary care. In this review, we summarized much progress achieved by applying metabolomics to ocular diseases and pointed out potential biomarkers and metabolic pathways involved to promote 3P medicine approach in healthcare.
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Olesen MA, Villavicencio-Tejo F, Quintanilla RA. The use of fibroblasts as a valuable strategy for studying mitochondrial impairment in neurological disorders. Transl Neurodegener 2022; 11:36. [PMID: 35787292 PMCID: PMC9251940 DOI: 10.1186/s40035-022-00308-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 05/26/2022] [Indexed: 11/10/2022] Open
Abstract
Neurological disorders (NDs) are characterized by progressive neuronal dysfunction leading to synaptic failure, cognitive impairment, and motor injury. Among these diseases, Alzheimer's disease (AD), Parkinson's disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS) have raised a significant research interest. These disorders present common neuropathological signs, including neuronal dysfunction, protein accumulation, oxidative damage, and mitochondrial abnormalities. In this context, mitochondrial impairment is characterized by a deficiency in ATP production, excessive production of reactive oxygen species, calcium dysregulation, mitochondrial transport failure, and mitochondrial dynamics deficiencies. These defects in mitochondrial health could compromise the synaptic process, leading to early cognitive dysfunction observed in these NDs. Interestingly, skin fibroblasts from AD, PD, HD, and ALS patients have been suggested as a useful strategy to investigate and detect early mitochondrial abnormalities in these NDs. In this context, fibroblasts are considered a viable model for studying neurodegenerative changes due to their metabolic and biochemical relationships with neurons. Also, studies of our group and others have shown impairment of mitochondrial bioenergetics in fibroblasts from patients diagnosed with sporadic and genetic forms of AD, PD, HD, and ALS. Interestingly, these mitochondrial abnormalities have been observed in the brain tissues of patients suffering from the same pathologies. Therefore, fibroblasts represent a novel strategy to study the genesis and progression of mitochondrial dysfunction in AD, PD, HD, and ALS. This review discusses recent evidence that proposes fibroblasts as a potential target to study mitochondrial bioenergetics impairment in neurological disorders and consequently to search for new biomarkers of neurodegeneration.
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Affiliation(s)
- Margrethe A Olesen
- Laboratory of Neurodegenerative Diseases, Facultad de Ciencias de La Salud, Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile
| | - Francisca Villavicencio-Tejo
- Laboratory of Neurodegenerative Diseases, Facultad de Ciencias de La Salud, Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile
| | - Rodrigo A Quintanilla
- Laboratory of Neurodegenerative Diseases, Facultad de Ciencias de La Salud, Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile.
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4
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Yang C, Zhang X, Ge X, He C, Liu S, Yang S, Huang C. N-Acetylcysteine protects against cobalt chloride-induced endothelial dysfunction by enhancing glucose-6-phosphate dehydrogenase activity. FEBS Open Bio 2022; 12:1475-1488. [PMID: 35666067 PMCID: PMC9340863 DOI: 10.1002/2211-5463.13449] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 05/05/2022] [Accepted: 06/03/2022] [Indexed: 11/07/2022] Open
Abstract
Hypoxia‐induced endothelial dysfunction is known to be involved in the pathogenesis of several vascular diseases. However, it remains unclear whether the pentose phosphate pathway (PPP) is involved in regulating the response of endothelial cells to hypoxia. Here, we established an in vitro model by treating EA.hy926 (a hybrid human umbilical vein cell line) with cobalt chloride (CoCl2; a chemical mimic that stabilizes HIF‐1α, thereby leading to the development of hypoxia), and used this to investigate the involvement of PPP by examining expression of its key enzyme, glucose‐6‐phosphate dehydrogenase (G6PD). We report that CoCl2 induces the accumulation of HIF‐1α, leading to endothelial cell dysfunction characterized by reduced cell viability, proliferation, tube formation, and activation of cytokine production, accompanied with a significant decrease in G6PD expression and activity. The addition of 6‐aminonicotinamide (6‐AN) to inhibit PPP directly causes endothelial dysfunction. Additionally, N‐Acetylcysteine (NAC), a precursor of glutathione, was further evaluated for its protective effects; NAC displayed a protective effect against CoCl2‐induced cell damage by enhancing G6PD activity, and this was abrogated by 6‐AN. The effects of CoCl2 and the involvement of G6PD in endothelial dysfunction have been confirmed in primary human aortic endothelial cells. In summary, G6PD was identified as a novel target of CoCl2‐induced damage, which highlighted the involvement of PPP in regulating the response of endothelial cell CoCl2. Treatment with NAC may be a potential strategy to treat hypoxia or ischemia, which are widely observed in vascular diseases.
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Affiliation(s)
- Chen Yang
- Department of Endocrinology and Diabetes, Xiamen Diabetes Institute, Fujian Key Laboratory of Translational Research for Diabetes, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, 361003, China.,Department of Geriatrics, Jinling Hospital, Medical School of Nanjing University, Nanjing, 210002, China
| | - Xiaofang Zhang
- Department of Endocrinology and Diabetes, Xiamen Diabetes Institute, Fujian Key Laboratory of Translational Research for Diabetes, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, 361003, China
| | - Xilin Ge
- Department of Endocrinology and Diabetes, Xiamen Diabetes Institute, Fujian Key Laboratory of Translational Research for Diabetes, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, 361003, China
| | - Chunmei He
- Department of Endocrinology and Diabetes, Xiamen Diabetes Institute, Fujian Key Laboratory of Translational Research for Diabetes, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, 361003, China
| | - Suhuan Liu
- Department of Endocrinology and Diabetes, Xiamen Diabetes Institute, Fujian Key Laboratory of Translational Research for Diabetes, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, 361003, China.,Research Center for Translational Medicine, the First Affiliated Hospital of Xiamen University, Xiamen, 361003, China
| | - Shuyu Yang
- Department of Endocrinology and Diabetes, Xiamen Diabetes Institute, Fujian Key Laboratory of Translational Research for Diabetes, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, 361003, China.,Traditional Chinese Medicine research studio, the First Affiliated Hospital of Xiamen University, Xiamen, 361003, China
| | - Caoxin Huang
- Department of Endocrinology and Diabetes, Xiamen Diabetes Institute, Fujian Key Laboratory of Translational Research for Diabetes, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, 361003, China
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Shosha E, Qin L, Lemtalsi T, Zaidi SAH, Rojas M, Xu Z, Caldwell RW, Caldwell RB, Fouda AY. Investigation of Retinal Metabolic Function in Type 1 Diabetic Akita Mice. Front Cardiovasc Med 2022; 9:900640. [PMID: 35722112 PMCID: PMC9201036 DOI: 10.3389/fcvm.2022.900640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/16/2022] [Indexed: 12/14/2022] Open
Abstract
Diabetic retinopathy (DR) is the leading cause of vision loss in working age adults. Understanding the retinal metabolic response to circulating high glucose levels in diabetic patients is critical for development of new therapeutics to treat DR. Measuring retinal metabolic function using the Seahorse analyzer is a promising technique to investigate the effect of hyperglycemia on retinal glycolysis and mitochondrial respiration. Here, we analyzed the retinal metabolic function in young and old diabetic and control mice. We also compared the expression of key glycolytic enzymes between the two groups. The Seahorse XF analyzer was used to measure the metabolic function of retina explants from young and old type 1 diabetic Akita (Ins2Akita) mice and their control littermates. Rate-limiting glycolytic enzymes were analyzed in retina lysates from the two age groups by Western blotting. Retinas from young adult Akita mice showed a decreased glycolytic response as compared to control littermates. However, this was not observed in the older mice. Western blotting analysis showed decreased expression of the glycolytic enzyme PFKFB3 in the young Akita mice retinas. Measurement of the oxygen consumption rate showed no difference in retinal mitochondrial respiration between Akita and WT littermates under normal glucose conditions ex vivo despite mitochondrial fragmentation in the Akita retinas as examined by electron microscopy. However, Akita mice retinas showed decreased mitochondrial respiration under glucose-free conditions. In conclusion, diabetic retinas display a decreased glycolytic response during the early course of diabetes which is accompanied by a reduction in PFKFB3. Diabetic retinas exhibit decreased mitochondrial respiration under glucose deprivation.
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Affiliation(s)
- Esraa Shosha
- Vascular Biology Center, Augusta University, Augusta, GA, United States
- Department of Clinical Pharmacy, Faculty of Pharmacy, Cairo University, Giza, Egypt
- University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Luke Qin
- Vascular Biology Center, Augusta University, Augusta, GA, United States
| | - Tahira Lemtalsi
- Vascular Biology Center, Augusta University, Augusta, GA, United States
- Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Syed A. H. Zaidi
- Vascular Biology Center, Augusta University, Augusta, GA, United States
- Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Modesto Rojas
- Vascular Biology Center, Augusta University, Augusta, GA, United States
- Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Zhimin Xu
- Vascular Biology Center, Augusta University, Augusta, GA, United States
- Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Robert William Caldwell
- Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA, United States
| | - Ruth B. Caldwell
- Vascular Biology Center, Augusta University, Augusta, GA, United States
- Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
- *Correspondence: Ruth B. Caldwell,
| | - Abdelrahman Y. Fouda
- Department of Clinical Pharmacy, Faculty of Pharmacy, Cairo University, Giza, Egypt
- University of Arkansas for Medical Sciences, Little Rock, AR, United States
- Abdelrahman Y. Fouda,
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Vallée A. Curcumin and Wnt/β‑catenin signaling in exudative age‑related macular degeneration (Review). Int J Mol Med 2022; 49:79. [PMID: 35445729 PMCID: PMC9083851 DOI: 10.3892/ijmm.2022.5135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/11/2022] [Indexed: 11/06/2022] Open
Abstract
Curcumin is a natural product widely used due to its pharmacological effects. Nevertheless, only a limited number of studies concerning the effects of curcumin on exudative age‑related macular degeneration (AMD) is currently available. Since ophthalmic diseases, including exudative AMD, have a marked impact on public health, the prevention and therapy of ophthalmic disorders remain of increasing concern. Exudative AMD is characterized by choroidal neovascularization (CNV) invading the subretinal space, ultimately enhancing exudation and hemorrhaging. The exudative AMD subtype corresponds to 10 to 15% of cases of macular degeneration; however, the occurrence of this subtype has been reported as the major cause of vision loss and blindness, with the occurrence of CNV being responsible for 80% of the cases with vision loss. In CNV increased expression of VEGF has been observed, stimulated by the overactivation of Wnt/β‑catenin signaling pathway. The stimulation of the Wnt/β‑catenin signaling pathway is responsible for the activation of several cellular mechanisms, simultaneously enhancing inflammation, oxidative stress and angiogenesis in numerous diseases, including ophthalmic disorders. Some studies have previously demonstrated the possible advantage of the use of curcumin for the inhibition of Wnt/β‑catenin signaling. In the present review article, the different mechanisms of curcumin are described concerning its effects on oxidative stress, inflammation and angiogenesis in exudative AMD, by interacting with Wnt/β‑catenin signaling.
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Affiliation(s)
- Alexandre Vallée
- Department of Epidemiology-Data-Biostatistics, Delegation of Clinical Research and Innovation (DRCI), Foch Hospital, 92150 Suresnes, France
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7
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Louer EMM, Yi G, Carmone C, Robben J, Stunnenberg HG, den Hollander AI, Deen PMT. Genes Involved in Energy Metabolism Are Differentially Expressed During the Day-Night Cycle in Murine Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2020; 61:49. [PMID: 32460311 PMCID: PMC7405837 DOI: 10.1167/iovs.61.5.49] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Purpose The functional interaction between photoreceptors and retinal pigment epithelium (RPE) cells is essential for vision. Phagocytosis of photoreceptor outer segments (POSs) by the RPE follows a circadian pattern; however, it remains unknown whether other RPE processes follow a daily rhythm. Therefore, our aim was to identify RPE processes following a daily rhythm. Methods Murine RPE was isolated at Zeitgeber time (ZT) 0, 2, 4, 9, 14, and 19 (n = 5 per time point), after which RNA was isolated and sequenced. Genes with a significant difference in expression between time points (P < 0.05) were subjected to EnrichR pathway analysis to identify daily rhythmic processes. Results Pathway enrichment revealed 13 significantly enriched KEGG pathways (P < 0.01), including the metabolic pathway (P = 0.002821). Analysis of the metabolic pathway differentially expressed genes revealed that genes involved in adenosine triphosphate production, glycolysis, glycogenolysis, and glycerophospholipid were low at ZT0 (light onset) and high at ZT19 (night). Genes involved in fatty acid degradation and cholesterol synthesis were high at light onset and low at night. Conclusions Our transcriptome data suggest that the highest energy demand of RPE cells is at night, whereas POS phagocytosis and degradation take place in the morning. Furthermore, we identified genes involved in fatty acid and glycerophospholipid synthesis that are upregulated at night, possibly playing a role in generating building blocks for membrane synthesis.
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8
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Autophagy in Age-Related Macular Degeneration: A Regulatory Mechanism of Oxidative Stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:2896036. [PMID: 32831993 PMCID: PMC7429811 DOI: 10.1155/2020/2896036] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/18/2020] [Indexed: 02/06/2023]
Abstract
Age-related macular degeneration (AMD) is a leading cause of severe visual loss and irreversible blindness in the elderly population worldwide. Retinal pigment epithelial (RPE) cells are the major site of pathological alterations in AMD. They are responsible for the phagocytosis of shed photoreceptor outer segments (POSs) and clearance of cellular waste under physiological conditions. Age-related, cumulative oxidative stimuli contribute to the pathogenesis of AMD. Excessive oxidative stress induces RPE cell degeneration and incomplete digestion of POSs, leading to the continuous accumulation of cellular waste (such as lipofuscin). Autophagy is a major system of degradation of damaged or unnecessary proteins. However, degenerative RPE cells in AMD patients cannot perform autophagy sufficiently to resist oxidative damage. Increasing evidence supports the idea that enhancing the autophagic process can properly alleviate oxidative injury in AMD and protect RPE and photoreceptor cells from degeneration and death, although overactivated autophagy may lead to cell death at early stages of retinal degenerative diseases. The crosstalk among the NFE2L2, PGC-1, p62, AMPK, and PI3K/Akt/mTOR pathways may play a crucial role in improving disturbed autophagy and mitigating the progression of AMD. In this review, we discuss how autophagy prevents oxidative damage in AMD, summarize potential neuroprotective strategies for therapeutic interventions, and provide an overview of these neuroprotective mechanisms.
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Sinha T, Naash MI, Al-Ubaidi MR. The Symbiotic Relationship between the Neural Retina and Retinal Pigment Epithelium Is Supported by Utilizing Differential Metabolic Pathways. iScience 2020; 23:101004. [PMID: 32252018 PMCID: PMC7132098 DOI: 10.1016/j.isci.2020.101004] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 01/09/2020] [Accepted: 03/18/2020] [Indexed: 12/13/2022] Open
Abstract
The neural retina and retinal pigment epithelium (RPE) maintain a symbiotic metabolic relationship, disruption of which leads to debilitating vision loss. The current study was undertaken to identify the differences in the steady-state metabolite levels and the pathways functioning between bona fide neural retina and RPE. Global metabolomics and cluster analyses identified 650 metabolites differentially modulated between the murine neural retina and RPE. Of these, 387 and 163 were higher in the RPE and the neural retina, respectively. Further analysis coupled with transcript and protein level investigations revealed that under normal physiological conditions, the RPE utilizes the pentose phosphate (>3-fold in RPE), serine (>10-fold in RPE), and sphingomyelin biosynthesis (>5-fold in RPE) pathways. Conversely, the neural retina relied mostly on glycolysis. These results show how the RPE and the neural retina have acquired an efficient, complementary and metabolically diverse symbiotic niche to support each other's distinct functions.
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Affiliation(s)
- Tirthankar Sinha
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA.
| | - Muayyad R Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA.
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10
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Vallée A, Lecarpentier Y, Vallée R, Guillevin R, Vallée JN. Circadian Rhythms in Exudative Age-Related Macular Degeneration: The Key Role of the Canonical WNT/β-Catenin Pathway. Int J Mol Sci 2020; 21:ijms21030820. [PMID: 32012797 PMCID: PMC7037737 DOI: 10.3390/ijms21030820] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/23/2020] [Accepted: 01/27/2020] [Indexed: 02/07/2023] Open
Abstract
Age-related macular degeneration (AMD) is considered as the main worldwide cause of blindness in elderly adults. Exudative AMD type represents 10 to 15% of macular degeneration cases, but is the main cause of vision loss and blindness. Circadian rhythm changes are associated with aging and could further accelerate it. However, the link between circadian rhythms and exudative AMD is not fully understood. Some evidence suggests that dysregulation of circadian functions could be manifestations of diseases or could be risk factors for the development of disease in elderly adults. Biological rhythms are complex systems interacting with the environment and control several physiological pathways. Recent findings have shown that the dysregulation of circadian rhythms is correlated with exudative AMD. One of the main pathways involved in exudative AMD is the canonical WNT/β-catenin pathway. Circadian clocks have a main role in some tissues by driving the circadian expression of genes involved in physiological and metabolic functions. In exudative AMD, the increase of the canonical WNT/β-catenin pathway is enhanced by the dysregulation of circadian rhythms. Exudative AMD progression is associated with major metabolic reprogramming, initiated by aberrant WNT/β-catenin pathway, of aerobic glycolysis. This review focuses on the interest of circadian rhythm dysregulation in exudative AMD through the aberrant upregulation of the canonical WNT/β-catenin pathway.
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Affiliation(s)
- Alexandre Vallée
- DACTIM-MIS, Laboratory of Mathematics and Applications (LMA), UMR CNRS 7348, University of Poitiers, CHU de Poitiers, 86021 Poitiers, France
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l'Est Francilien (GHEF), 77100 Meaux, France
| | - Rodolphe Vallée
- University Hospital Group of Paris-Seine-Saint-Denis, APHP, University of Paris-13 Sorbonne Paris-Cité, 93000 Paris, France
| | - Rémy Guillevin
- DACTIM-MIS, Laboratory of Mathematics and Applications (LMA), UMR CNRS 7348, University of Poitiers, CHU de Poitiers, 86021 Poitiers, France
| | - Jean-Noël Vallée
- CHU Amiens Picardie, University of Picardie Jules Verne (UPJV), 80000 Amiens, France
- Laboratory of Mathematics and Applications (LMA), UMR CNRS 7348, University of Poitiers, 86021 Poitiers, France
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11
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Nawaz IM, Rezzola S, Cancarini A, Russo A, Costagliola C, Semeraro F, Presta M. Human vitreous in proliferative diabetic retinopathy: Characterization and translational implications. Prog Retin Eye Res 2019; 72:100756. [PMID: 30951889 DOI: 10.1016/j.preteyeres.2019.03.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 03/26/2019] [Accepted: 03/28/2019] [Indexed: 02/07/2023]
Abstract
Diabetic retinopathy (DR) is one of the leading causes of visual impairment in the working-age population. DR is a progressive eye disease caused by long-term accumulation of hyperglycaemia-mediated pathological alterations in the retina of diabetic patients. DR begins with asymptomatic retinal abnormalities and may progress to advanced-stage proliferative diabetic retinopathy (PDR), characterized by neovascularization or preretinal/vitreous haemorrhages. The vitreous, a transparent gel that fills the posterior cavity of the eye, plays a vital role in maintaining ocular function. Structural and molecular alterations of the vitreous, observed during DR progression, are consequences of metabolic and functional modifications of the retinal tissue. Thus, vitreal alterations reflect the pathological events occurring at the vitreoretinal interface. These events are caused by hypoxic, oxidative, inflammatory, neurodegenerative, and leukostatic conditions that occur during diabetes. Conversely, PDR vitreous can exert pathological effects on the diabetic retina, resulting in activation of a vicious cycle that contributes to disease progression. In this review, we recapitulate the major pathological features of DR/PDR, and focus on the structural and molecular changes that characterize the vitreal structure and composition during DR and progression to PDR. In PDR, vitreous represents a reservoir of pathological signalling molecules. Therefore, in this review we discuss how studying the biological activity of the vitreous in different in vitro, ex vivo, and in vivo experimental models can provide insights into the pathogenesis of PDR. In addition, the vitreous from PDR patients can represent a novel tool to obtain preclinical experimental evidences for the development and characterization of new therapeutic drug candidates for PDR therapy.
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Affiliation(s)
- Imtiaz M Nawaz
- Department of Molecular and Translational Medicine, University of Brescia, Italy
| | - Sara Rezzola
- Department of Molecular and Translational Medicine, University of Brescia, Italy
| | - Anna Cancarini
- Department of Ophthalmology, University of Brescia, Italy
| | - Andrea Russo
- Department of Ophthalmology, University of Brescia, Italy
| | - Ciro Costagliola
- Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy
| | | | - Marco Presta
- Department of Molecular and Translational Medicine, University of Brescia, Italy.
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Haines NR, Manoharan N, Olson JL, D'Alessandro A, Reisz JA. Metabolomics Analysis of Human Vitreous in Diabetic Retinopathy and Rhegmatogenous Retinal Detachment. J Proteome Res 2018; 17:2421-2427. [PMID: 29877085 DOI: 10.1021/acs.jproteome.8b00169] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The vitreous humor is a highly aqueous eye fluid interfacing with the retina and lens and providing shape. Its molecular composition provides a readout for the eye's physiological status. Changes in cellular metabolism underlie vitreoretinal pathologies, but despite routine surgical collection of vitreous, only limited reports of metabolism in the vitreous of human patients have been described. Vitreous samples from patients with rhegmatogenous retinal detachment ( n = 25) and proliferative diabetic retinopathy ( n = 9) were profiled along with control human vitreous samples ( n = 8) by untargeted mass-spectrometry-based metabolomics. Profound changes were observed in diabetic retinopathy vitreous, including altered glucose metabolism and activation of the pentose phosphate pathway, which provides reducing equivalents to counter oxidative stress. In addition, purine metabolism was altered in diabetic retinopathy, with decreased xanthine and elevated levels of related purines (inosine, hypoxanthine, urate, allantoate) generated in oxidant-producing reactions. In contrast, the vitreous metabolite profiles of retinal detachment patients were similar to controls. In total, our results suggest a rewiring of vitreous metabolism in diabetic retinopathy that underlies disease features such as oxidative stress and furthermore illustrates how the vitreous metabolic profile may be impacted by disease.
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Affiliation(s)
- Nathan R Haines
- Department of Ophthalmology , University of Colorado , Anschutz Medical Campus , Aurora , Colorado 80045 , United States
| | - Niranjan Manoharan
- Department of Ophthalmology , University of Colorado , Anschutz Medical Campus , Aurora , Colorado 80045 , United States
| | - Jeffrey L Olson
- Department of Ophthalmology , University of Colorado , Anschutz Medical Campus , Aurora , Colorado 80045 , United States
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics , University of Colorado , Anschutz Medical Campus , Aurora , Colorado 80045 , United States
| | - Julie A Reisz
- Department of Biochemistry and Molecular Genetics , University of Colorado , Anschutz Medical Campus , Aurora , Colorado 80045 , United States
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Zhu S, Yam M, Wang Y, Linton JD, Grenell A, Hurley JB, Du J. Impact of euthanasia, dissection and postmortem delay on metabolic profile in mouse retina and RPE/choroid. Exp Eye Res 2018; 174:113-120. [PMID: 29864440 DOI: 10.1016/j.exer.2018.05.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 01/02/2023]
Abstract
Metabolomics studies in the retina and retinal pigment epithelium (RPE) in animal models or postmortem donors are essential to understanding the retinal metabolism and to revealing the underlying mechanisms of retinal degenerative diseases. We have studied how different methods of euthanasia (CO2 or cervical dislocation) different isolation procedures and postmortem delay affect metabolites in mouse retina and RPE/choroid using LC MS/MS and GC MS. Compared with cervical dislocation, CO2 exposure for 5 min dramatically degrades ATP and GTP into purine metabolites in the retina while raising intermediates in glucose metabolism and amino acids in the RPE/choroid. Isolation in cold buffer containing glucose has the least change in metabolites. Postmortem delay time-dependently and differentially impacts metabolites in the retina and RPE/choroid. In the postmortem retina, 18% of metabolites were changed at 0.5 h (h), 41% at 4 h and 51% at 8 h. However, only 6% of metabolites were changed in the postmortem RPE/choroid and it steadily increased to 20% at 8 h. Notably, both postmortem retina and RPE/choroid tissue showed increased purine metabolites. Storage of eyes in cold nutrient-rich medium substantially blocked the postmortem change in the retina and RPE/choroid. In conclusion, our study provides optimized methods to prepare fresh or postmortem retina and RPE/choroid tissue for metabolomics studies.
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Affiliation(s)
- Siyan Zhu
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506, USA; Department of Biochemistry, West Virginia University, Morgantown, WV 26506, USA
| | - Michelle Yam
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506, USA; Department of Biochemistry, West Virginia University, Morgantown, WV 26506, USA
| | - Yekai Wang
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506, USA; Department of Biochemistry, West Virginia University, Morgantown, WV 26506, USA
| | - Jonathan D Linton
- Department of Biochemistry, University of Washington, Seattle, WA 98109, USA
| | - Allison Grenell
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506, USA; Department of Biochemistry, West Virginia University, Morgantown, WV 26506, USA
| | - James B Hurley
- Department of Biochemistry, University of Washington, Seattle, WA 98109, USA; Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
| | - Jianhai Du
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506, USA; Department of Biochemistry, West Virginia University, Morgantown, WV 26506, USA.
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Vallée A, Lecarpentier Y, Guillevin R, Vallée JN. PPARγ agonists: Potential treatments for exudative age-related macular degeneration. Life Sci 2017; 188:123-130. [PMID: 28887057 DOI: 10.1016/j.lfs.2017.09.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 08/29/2017] [Accepted: 09/05/2017] [Indexed: 12/22/2022]
Abstract
Choroidal neovascularization (CNV) characterizes the progression of exudative age-related macular degeneration (AMD) with the deterioration in the central vision. Vascular inflammation, and overproduction of inflammatory cytokines, growth factors and aberrant endothelial cell migration, initiate defective blood vessel proliferation in exudative AMD. CNV formation is initiated by the interplay between inflammation, the hallmark of exudative AMD, and the activation of WNT/β-catenin pathway. Upregulation of WNT/β-catenin pathway involves activation of PI3K/Akt pathway and then the Warburg effect to produce lactate. Lactate production generates VEGF expression and then participates to the initiation of CNV in exudative AMD. WNT/β-catenin pathway and PPARγ act in an opposite manner in several diseases. We focus this review on the interplay between PPARγ and canonical WNT/β-catenin pathway and the anti-inflammatory role of PPARγ in exudative AMD. In exudative AMD, PPARγ agonists downregulate inflammation and the WNT/β-catenin pathway. PPARγ agonists can appear as promising treatment against the initiation and the progression of CNV in exudative AMD.
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Affiliation(s)
- Alexandre Vallée
- Experimental and Clinical Neurosciences Laboratory, INSERM U1084, University of Poitiers, Poitiers, France; Laboratoire de Mathématiques et Applications (LMA), UMR CNRS 7348, Université de Poitiers, France.
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l'Est Francilien (GHEF), Meaux, France
| | - Rémy Guillevin
- Université de Poitiers et CHU de Poitiers, DACTIM, Laboratoire de Mathématiques et Applications, UMR CNRS 7348, SP2MI, Futuroscope, France
| | - Jean-Noël Vallée
- Laboratoire de Mathématiques et Applications (LMA), UMR CNRS 7348, Université de Poitiers, France; CHU Amiens Picardie, Université Picardie Jules Verne (UPJV), Amiens, France
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15
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Vallée A, Lecarpentier Y, Guillevin R, Vallée JN. Aerobic Glycolysis Hypothesis Through WNT/Beta-Catenin Pathway in Exudative Age-Related Macular Degeneration. J Mol Neurosci 2017; 62:368-379. [PMID: 28689265 DOI: 10.1007/s12031-017-0947-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 06/28/2017] [Indexed: 12/18/2022]
Abstract
Exudative age-related macular degeneration (AMD) is characterized by molecular mechanisms responsible for the initiation of choroidal neovascularization (CNV). Inflammatory processes are associated with upregulation of the canonical WNT/beta-catenin pathway in exudative AMD. We focus this review on the link between WNT/beta-catenin pathway activation and neovascular progression in exudative AMD through activation of aerobic glycolysis for production of angiogenic factors. Increased WNT/beta-catenin pathway involves hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2). WNT/beta-catenin pathway stimulates PI3K/Akt pathway and then HIF-1alpha which activates glycolytic enzymes: glucose transporter (Glut), pyruvate dehydrogenase kinase 1 (PDK1), lactate dehydrogenase A (LDH-A), and monocarboxylate lactate transporter (MCT-1). This phenomenon is called aerobic glycolysis or the Warburg effect. Consequently, phosphorylation of PDK-1 inhibits the pyruvate dehydrogenase complex (PDH). Thus, a large part of pyruvate cannot be converted into acetyl-CoA in mitochondria and only a part of acetyl-CoA can enter the tricarboxylic acid cycle. Cytosolic pyruvate is converted into lactate through the action of LDH-A. In exudative AMD, high level of cytosolic lactate is correlated with increase of VEGF expression, the angiogenic factor of CNV. Photoreceptors in retina cells can metabolize glucose through aerobic glycolysis to protect them against oxidative damage, as cancer cells do.
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Affiliation(s)
- Alexandre Vallée
- Experimental and Clinical Neurosciences Laboratory, INSERM U1084, University of Poitiers, Poitiers, France.
- Laboratoire de Mathématiques et Applications (LMA), UMR CNRS 7348, Université de Poitiers, 11 Boulevard Marie et Pierre Curie, Poitiers, France.
| | | | - Rémy Guillevin
- DACTIM, Laboratoire de Mathématiques et Applications, Université de Poitiers et CHU de Poitiers, UMR CNRS 7348, SP2MI Futuroscope, Chasseneuil-du-Poitou, France
| | - Jean-Noël Vallée
- Laboratoire de Mathématiques et Applications (LMA), UMR CNRS 7348, Université de Poitiers, 11 Boulevard Marie et Pierre Curie, Poitiers, France
- CHU Amiens Picardie, Université Picardie Jules Verne (UPJV), Amiens, France
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16
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Farnoodian M, Halbach C, Slinger C, Pattnaik BR, Sorenson CM, Sheibani N. High glucose promotes the migration of retinal pigment epithelial cells through increased oxidative stress and PEDF expression. Am J Physiol Cell Physiol 2016; 311:C418-36. [PMID: 27440660 DOI: 10.1152/ajpcell.00001.2016] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 07/18/2016] [Indexed: 12/11/2022]
Abstract
Defects in the outer blood-retinal barrier have significant impact on the pathogenesis of diabetic retinopathy and macular edema. However, the detailed mechanisms involved remain largely unknown. This is, in part, attributed to the lack of suitable animal and cell culture models, including those of mouse origin. We recently reported a method for the culture of retinal pigment epithelial (RPE) cells from wild-type and transgenic mice. The RPE cells are responsible for maintaining the integrity of the outer blood-retinal barrier whose dysfunction during diabetes has a significant impact on vision. Here we determined the impact of high glucose on the function of RPE cells. We showed that high glucose conditions resulted in enhanced migration and increased the level of oxidative stress in RPE cells, but minimally impacted their rate of proliferation and apoptosis. High glucose also minimally affected the cell-matrix and cell-cell interactions of RPE cells. However, the expression of integrins and extracellular matrix proteins including pigment epithelium-derived factor (PEDF) were altered under high glucose conditions. Incubation of RPE cells with the antioxidant N-acetylcysteine under high glucose conditions restored normal migration and PEDF expression. These cells also exhibited increased nuclear localization of the antioxidant transcription factor Nrf2 and ZO-1, reduced levels of β-catenin and phagocytic activity, and minimal effect on production of vascular endothelial growth factor, inflammatory cytokines, and Akt, MAPK, and Src signaling pathways. Thus high glucose conditions promote RPE cell migration through increased oxidative stress and expression of PEDF without a significant effect on the rate of proliferation and apoptosis.
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Affiliation(s)
- Mitra Farnoodian
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Caroline Halbach
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Cassidy Slinger
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Bikash R Pattnaik
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; and
| | - Christine M Sorenson
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; and
| | - Nader Sheibani
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; and Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
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Osorio-Paz I, Uribe-Carvajal S, Salceda R. In the Early Stages of Diabetes, Rat Retinal Mitochondria Undergo Mild Uncoupling due to UCP2 Activity. PLoS One 2015; 10:e0122727. [PMID: 25951172 PMCID: PMC4423783 DOI: 10.1371/journal.pone.0122727] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 02/12/2015] [Indexed: 01/04/2023] Open
Abstract
In order to maintain high transmembrane ionic gradients, retinal tissues require a large amount of energy probably provided by a high rate of both, glycolysis and oxidative phosphorylation. However, little information exists on retinal mitochondrial efficiency. We analyzed the retinal mitochondrial activity in ex vivo retinas and in isolated mitochondria from normal rat retina and from short-term streptozotocin-diabetic rats. In normal ex vivo retinas, increasing glucose concentrations from 5.6mM to 30mM caused a four-fold increase in glucose accumulation and CO2 production. Retina from diabetic rats accumulated similar amounts of glucose. However, CO2 production was not as high. Isolated mitochondria from normal rat retina exhibited a resting rate of oxygen consumption of 14.6 ± 1.1 natgO (min.mg prot)-1 and a respiratory control of 4.0. Mitochondria from 7, 20 and 45 days diabetic rats increased the resting rate of oxygen consumption and the activity of the electron transport complexes; under these conditions the mitochondrial transmembrane potential decreased. In spite of this, the ATP synthesis was not modified. GDP, an UCP2 inhibitor, increased mitochondrial membrane potential and superoxide production in controls and at 45 days of diabetes. The role of UCP2 is discussed. The results suggest that at the early stage of diabetes we studied, retinal mitochondria undergo adaptations leading to maintain energetic requirements and prevent oxidative stress.
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Affiliation(s)
- Ixchel Osorio-Paz
- Departamento de Neurodesarrollo y Fisiología, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México Distrito Federal, México
| | - Salvador Uribe-Carvajal
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México Distrito Federal, México
| | - Rocío Salceda
- Departamento de Neurodesarrollo y Fisiología, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México Distrito Federal, México
- * E-mail:
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18
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Kanda A, Noda K, Ishida S. ATP6AP2/(pro)renin receptor contributes to glucose metabolism via stabilizing the pyruvate dehydrogenase E1 β subunit. J Biol Chem 2015; 290:9690-700. [PMID: 25720494 DOI: 10.1074/jbc.m114.626713] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Indexed: 12/27/2022] Open
Abstract
Aerobic glucose metabolism is indispensable for metabolically active cells; however, the regulatory mechanism of efficient energy generation in the highly evolved mammalian retina remains incompletely understood. Here, we revealed an unsuspected role for (pro)renin receptor, also known as ATP6AP2, in energy metabolism. Immunoprecipitation and mass spectrometry analyses identified the pyruvate dehydrogenase (PDH) complex as Atp6ap2-interacting proteins in the mouse retina. Yeast two-hybrid assays demonstrated direct molecular binding between ATP6AP2 and the PDH E1 β subunit (PDHB). Pdhb immunoreactivity co-localized with Atp6ap2 in multiple retinal layers including the retinal pigment epithelium (RPE). ATP6AP2 knockdown in RPE cells reduced PDH activity, showing a predilection to anaerobic glycolysis. ATP6AP2 protected PDHB from phosphorylation, thus controlling its protein stability. Down-regulated PDH activity due to ATP6AP2 knockdown inhibited glucose-stimulated oxidative stress in RPE cells. Our present data unraveled the novel function of ATP6AP2/(P)RR as a PDHB stabilizer, contributing to aerobic glucose metabolism together with oxidative stress.
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Affiliation(s)
- Atsuhiro Kanda
- From the Department of Ophthalmology, Laboratory of Ocular Cell Biology and Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Kousuke Noda
- From the Department of Ophthalmology, Laboratory of Ocular Cell Biology and Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
| | - Susumu Ishida
- From the Department of Ophthalmology, Laboratory of Ocular Cell Biology and Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
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19
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Hernández C, Garcia-Ramírez M, García-Rocha M, Saez-López C, Valverde ÁM, Guinovart JJ, Simó R. Glycogen storage in the human retinal pigment epithelium: a comparative study of diabetic and non-diabetic donors. Acta Diabetol 2014; 51:543-52. [PMID: 24458975 DOI: 10.1007/s00592-013-0549-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 12/18/2013] [Indexed: 01/18/2023]
Abstract
Liver and muscle glycogen content is reduced in diabetic patients but there is no information on the effect of diabetes on the glycogen content in the retinal pigment epithelium (RPE). The main aim of the study was to compare the glycogen content in the RPE between diabetic and non-diabetic human donors. Glycogen synthase (GS) and glycogen phosphorylase (GP), the key enzymes of glycogen metabolism, as well as their isoforms, were also assessed. For this purpose, 44 human postmortem eye cups were included (22 from 11 type 2 diabetic and 22 from 11 non-diabetic donors matched by age). Human RPE cells cultured in normoglycemic and hyperglycemic conditions were also analyzed. Glycogen content as well as the mRNA, protein content and enzyme activity of GS and GP were determined. In addition, GS and GP isoforms were characterized. In the RPE from diabetic donors, as well as in RPE cells grown in hyperglycemic conditions, the glycogen content was increased. The increase in glycogen content was associated with an increase in GS without changes in GP levels. In RPE form human donors, the muscle GS isoform but not the liver GS isoform was detected. Regarding GP, the muscle and brain isoform of GP but not the liver GP isoform were detected. We conclude that glycogen storage is increased in the RPE of diabetic patients, and it is associated with an increase in GS activity. Further studies aimed at determining the role of glycogen deposits in the pathogenesis of diabetic retinopathy are warranted.
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Affiliation(s)
- Cristina Hernández
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Pg. Vall d'Hebron 119-129, 08035, Barcelona, Spain,
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20
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Yokosako K, Mimura T, Funatsu H, Noma H, Goto M, Kamei Y, Kondo A, Matsubara M. Glycolysis in patients with age-related macular degeneration. Open Ophthalmol J 2014; 8:39-47. [PMID: 25191529 PMCID: PMC4150380 DOI: 10.2174/1874364101408010039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/18/2014] [Accepted: 07/21/2014] [Indexed: 12/31/2022] Open
Abstract
Purpose: Retinal adenosine triphosphate is mainly produced via glycolysis, so inhibition of glycolysis may promote the onset and progression of age-related macular degeneration (AMD). When glycolysis is inhibited, pyruvate is metabolized by lactic acid fermentation instead of entering the mitochondrial tricarboxylic acid (TCA) cycle. We measured urinary pyruvate and lactate levels in patients with AMD.
Methods: Eight patients with typical AMD (tAMD group) and 9 patients with polypoidal choroidal vasculopathy (PCV group) were enrolled. Urinary levels of pyruvate, lactate, α-hydroxybutyrate, and β-hydroxybutyrate were measured in all patients.
Results: The mean urinary levels of pyruvate and lactate were 8.0 ± 2.8 and 7.5 ± 8.3 μg/mg creatinine (reference values: 0.5-6.6 and 0.0-1.6), respectively, with the mean increase over the reference value being 83.6 ± 51.1% and 426.5 ± 527.8%, respectively. In 12 patients (70.6%), the lactate/pyruvate ratio was above the reference range. Urinary levels of α-hydroxybutyrate and β-hydroxybutyrate were decreased by -31.9 ± 15.2% and -33.1 ± 17.5% compared with the mean reference values. There were no significant differences of any of these glycolysis metabolites between the tAMD and PCV groups. Multivariate analysis revealed that none of the variables tested, including patient background factors (age, hypertension, diabetes, hyperlipidemia, cerebrovascular disease, alcohol, smoking, visual acuity, and AMD phenotype), were significantly associated with the lactate/pyruvate ratio.
Conclusion: A high lactate/pyruvate ratio is a well-known marker of mitochondrial impairment, and it indicates poor oxidative function in AMD. Our results suggest that increased lactate levels may be implicated in the pathogenesis of AMD.
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Affiliation(s)
- Kanako Yokosako
- Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan
| | - Tatsuya Mimura
- Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan
| | - Hideharu Funatsu
- Department of Ophthalmology, Yachiyo Medical Center, Tokyo Women's Medical University, Chiba, Japan
| | - Hidetaka Noma
- Department of Ophthalmology, Hachioji Medical Center, Tokyo Medical University, Tokyo, Japan
| | - Mari Goto
- Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan
| | - Yuko Kamei
- Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan
| | - Aki Kondo
- Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan
| | - Masao Matsubara
- Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan
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The chaperone-dependent ubiquitin ligase CHIP targets HIF-1α for degradation in the presence of methylglyoxal. PLoS One 2010; 5:e15062. [PMID: 21124777 PMCID: PMC2993942 DOI: 10.1371/journal.pone.0015062] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 10/17/2010] [Indexed: 11/24/2022] Open
Abstract
Hypoxia-inducible factor-1 (HIF-1) plays a key role in cell adaptation to low oxygen and stabilization of HIF-1 is vital to ensure cell survival under hypoxia. Diabetes has been associated with impairment of the cell response to hypoxia and downregulation of HIF-1 is most likely the event that transduces hyperglycemia into increased cell death in diabetes-associated hypoxia. In this study, we aimed at identifying the molecular mechanism implicated in destabilization of HIF-1 by high glucose. In this work, we identified a new molecular mechanism whereby methylglyoxal (MGO), which accumulates in high-glucose conditions, led to a rapid proteasome-dependent degradation of HIF-1α under hypoxia. Significantly, MGO-induced degradation of HIF-1α did not require the recruitment of the ubiquitin ligase pVHL nor did it require hydroxylation of the proline residues P402/P564 of HIF-1α. Moreover, we identified CHIP (Carboxy terminus of Hsp70-Interacting Protein) as the E3 ligase that ubiquitinated HIF-1α in the presence of MGO. Consistently, silencing of endogenous CHIP and overexpression of glyoxalase I both stabilized HIF-1α under hypoxia in the presence of MGO. Data shows that increased association of Hsp40/70 with HIF-1α led to recruitment of CHIP, which promoted polyubiquitination and degradation of HIF-1α. Moreover, MGO-induced destabilization of HIF-1α led to a dramatic decrease in HIF-1 transcriptional activity. Altogether, data is consistent with a new pathway for degradation of HIF-1α in response to intracellular accumulation of MGO. Moreover, we suggest that accumulation of MGO is likely to be the link between high glucose and the loss of cell response to hypoxia in diabetes.
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22
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Turgut B, Gul FC, Ilhan N, Demir T, Celiker U. Comparison of serum glycosylated hemoglobin levels in patients with diabetic cystoid macular edema with and without serous macular detachment. Indian J Ophthalmol 2010; 58:381-4. [PMID: 20689191 PMCID: PMC2992911 DOI: 10.4103/0301-4738.67044] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Aim: A clinical comparative trial was conducted to compare the levels of glycosylated hemoglobin (HbA1c) in patients with diabetic cystoid macular edema (CME) with and without serous macula detachment (SMD). Materials and Methods: Thirty patients (group 1) with diabetic CME in both eyes, but without SMD, and 30 patients (group 2) with diabetic CME and SMD in both eyes documented by optical coherence tomography (OCT) and fundus fluorescein angiography (FFA), were included in the study. In addition to the measurement of central macular thickness by OCT and visual acuity (VA) (as logMAR) using the the early treatment diabetic retinopathy study (ETDRS) chart, the concentrations of HbA1c were measured by high performance liquid chromatography (HPLC). Statistical analysis was done by independent samples t test. Results: The mean logMAR VA was 0.8 ± 0.22 (1.0–0.5) in group 1and 0.7 ± 0.16 (1.0–0.6) in group 2. The mean central macular thickness, as determined by OCT, was 468.70 ± 70.44 μm (344–602 μm) in group 1 and 477.80 ± 73.34 μm (354–612 μm) in group 2. The difference between the groups was not statistically significant (P = 0.626). The mean HbA1c levels were 8.16 ± 0.99% in group 1 and 10.05 ± 1.66% in group 2. The difference between the groups was statistically significant (P < 0.001). Conclusions: The presence of SMD and high HbA1c levels in the patients with diabetic CME may be indirectly suggestive of retinal pigment epithelium dysfunction.
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Affiliation(s)
- Burak Turgut
- Department of Ophthalmology, Firat University School of Medicine, Elazig, Turkey
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23
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Santiago AR, Garrido MJ, Cristóvão AJ, Duarte JMN, Carvalho RA, Ambrósio AF. Evaluation of the Impact of Diabetes on Retinal Metabolites by NMR Spectroscopy. Curr Eye Res 2010; 35:992-1001. [DOI: 10.3109/02713683.2010.500113] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- A. R. Santiago
- Center for Neuroscience and Cell Biology, Department of Zoology, University of Coimbra, Coimbra, Portugal
- Center of Ophthalmology and Visual Sciences, IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - M. J. Garrido
- Center for Neuroscience and Cell Biology, Department of Zoology, University of Coimbra, Coimbra, Portugal
| | - A. J. Cristóvão
- Center for Neuroscience and Cell Biology, Department of Zoology, University of Coimbra, Coimbra, Portugal
- Department of Zoology, University of Coimbra, Coimbra, Portugal
| | - J. M. N. Duarte
- Center for Neuroscience and Cell Biology, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - R. A. Carvalho
- Center for Neuroscience and Cell Biology, Department of Zoology, University of Coimbra, Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal
| | - A. F. Ambrósio
- Center for Neuroscience and Cell Biology, Department of Zoology, University of Coimbra, Coimbra, Portugal
- Center of Ophthalmology and Visual Sciences, IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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Methylglyoxal alters the function and stability of critical components of the protein quality control. PLoS One 2010; 5:e13007. [PMID: 20885985 PMCID: PMC2945773 DOI: 10.1371/journal.pone.0013007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Accepted: 09/06/2010] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Increased production and accumulation of methylglyoxal (MGO), as well as increased modification of proteins by glycoxidation, are hallmarks of aging and diabetes. MGO was shown to modify proteins and to contribute to the accumulation of damaged proteins that can be toxic to cells. However, the effect of MGO on the cell systems responsible for repairing or degrading damaged proteins is still unclear. In this study, the effect of MGO on the function of the ubiquitin-proteasome system (UPS) and on molecular chaperones, two cooperative mechanisms associated with protein quality control, was investigated. PRINCIPAL FINDINGS In this work it is shown that treatment of cells with MGO leads to accumulation of ubiquitin conjugates and depletion of free ubiquitin. Moreover, MGO significantly decreases the proteolytic activity of the 20S proteasome. Data further shows that MGO decreases the levels of the molecular chaperones Hsc70 and Hsp90 and leads to accumulation of CHIP-, Hsp40- and ubiquitin-containing aggregates. The formation of large aggregates containing CHIP is a consequence of its binding to misfolded proteins and to molecular chaperones. Moreover, dysfunction of the chaperones/CHIP/UPS axis is associated with accumulation of oxidized and argpyrimidine-modified proteins, which is likely to be associated with decreased cell viability. Interestingly, data further shows that MGO-induced stress induces the activation of heat shock factor-1 (Hsf-1), the main transcription factor involved in the regulation of the expression of heat shock proteins (HSPs) and cell response to stress. CONCLUSIONS The data obtained in this work suggests that MGO impairs both the UPS and the protein quality control dependent on CHIP and molecular chaperones, leading to accumulation of toxic aggregates and increased cell death. However, these MGO-induced changes appear to elicit a response from the Hsf-1 system, which is crucial to help cells to cope with cellular stress and to re-establish homeostasis.
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Abstract
The glycemic index (GI) indicates how fast blood glucose is raised after consuming a carbohydrate-containing food. Human metabolic studies indicate that GI is related to patho-physiological responses after meals. Compared with a low-GI meal, a high-GI meal is characterized with hyperglycemia during the early postprandial stage (0-2h) and a compensatory hyperlipidemia associated with counter-regulatory hormone responses during late postprandial stage (4-6h). Over the past three decades, several human health disorders have been related to GI. The strongest relationship suggests that consuming low-GI foods prevents diabetic complications. Diabetic retinopathy (DR) is a complication of diabetes. In this aspect, GI appears to be useful as a practical guideline to help diabetic people choose foods. Abundant epidemiological evidence also indicates positive associations between GI and risk for type 2 diabetes, cardiovascular disease, and more recently, age-related macular degeneration (AMD) in people without diabetes. Although data from randomized controlled intervention trials are scanty, these observations are strongly supported by evolving molecular mechanisms which explain the pathogenesis of hyperglycemia. This wide range of evidence implies that dietary hyperglycemia is etiologically related to human aging and diseases, including DR and AMD. In this context, these diseases can be considered as metabolic retinal diseases. Molecular theories that explain hyperglycemic pathogenesis involve a mitochondria-associated pathway and four glycolysis-associated pathways, including advanced glycation end products formation, protein kinase C activation, polyol pathway, and hexosamine pathway. While the four glycolysis-associated pathways appear to be universal for both normoxic and hypoxic conditions, the mitochondria-associated mechanism appears to be most relevant to the hyperglycemic, normoxic pathogenesis. For diseases that affect tissues with highly active metabolism and that frequently face challenge from low oxygen tension, such as retina in which metabolism is determined by both glucose and oxygen homeostases, these theories appear to be insufficient. Several lines of evidence indicate that the retina is particularly vulnerable when hypoxia coincides with hyperglycemia. We propose a novel hyperglycemic, hypoxia-inducible factor (HIF) pathway, to complement the current theories regarding hyperglycemic pathogenesis. HIF is a transcription complex that responds to decrease oxygen in the cellular environment. In addition to playing a significant role in the regulation of glucose metabolism, under hyperglycemia HIF has been shown to increase the expression of HIF-inducible genes, such as vascular endothelial growth factor (VEGF) leading to angiogenesis. To this extent, we suggest that HIF can also be described as a hyperglycemia-inducible factor. In summary, while management of dietary GI appears to be an effective intervention for the prevention of metabolic diseases, specifically AMD and DR, more interventional data is needed to evaluate the efficacy of GI management. There is an urgent need to develop reliable biomarkers of exposure, surrogate endpoints, as well as susceptibility for GI. These insights would also be helpful in deciphering the detailed hyperglycemia-related biochemical mechanisms for the development of new therapeutic agents.
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Rothermel A, Weigel W, Pfeiffer-Guglielmi B, Hamprecht B, Robitzki AA. Immunocytochemical analysis of glycogen phosphorylase isozymes in the developing and adult retina of the domestic chicken (Gallus domesticus). Neurochem Res 2007; 33:336-47. [PMID: 17940897 DOI: 10.1007/s11064-007-9477-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Accepted: 08/15/2007] [Indexed: 11/26/2022]
Abstract
Glycogen is the major energy reserve in neural tissues including the retina. A key-enzyme in glycogen metabolism is glycogen phosphorylase (GP) which exists in three differentially regulated isoforms. By applying isozyme-specific antibodies it could be demonstrated that the GP BB (brain), but not the GP MM (muscle) isoform is expressed in the chicken retina in neuronal and glial (Müller) cells. In the embryonic chicken retina, GP showed a development-dependent expression pattern. Double-labeling experiments with cell type-specific antibodies revealed that GP is expressed in various layers of the retina some of which, e.g., the photoreceptor inner segments, are known to be sites of high energy consumption. This suggests important roles of GP BB, and therefore glycogen, in early differentiation, spontaneous wave generation and in formation and stabilization of synapses.
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Affiliation(s)
- Andrée Rothermel
- Molekularbiologisch-biochemische Prozesstechnik, Biotechnologisch-Biomedizinisches Zentrum, Universität Leipzig, Deutscher Platz 5, Leipzig 04103, Germany
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