scholarly journals Deletion of TSPO Resulted in Change of Metabolomic Profile in Retinal Pigment Epithelial Cells

2019 ◽  
Vol 20 (6) ◽  
pp. 1387 ◽  
Author(s):  
Abdulwahab Alamri ◽  
Lincoln Biswas ◽  
David Watson ◽  
Xinhua Shu
Keyword(s):  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Nucleotide Metabolism ◽  
Retinal Pigment Epithelial Cells ◽  
Age Related Macular Degeneration ◽  
Clinical Feature ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Age Related ◽  
The Impact

Age-related macular degeneration is the main cause of vision loss in the aged population worldwide. Drusen, extracellular lesions formed underneath the retinal pigment epithelial (RPE) cells, are a clinical feature of AMD and associated with AMD progression. RPE cells support photoreceptor function by providing nutrition, phagocytosing outer segments and removing metabolic waste. Dysfunction and death of RPE cells are early features of AMD. The translocator protein, TSPO, plays an important role in RPE cholesterol efflux and loss of TSPO results in increased intracellular lipid accumulation and reactive oxygen species (ROS) production. This study aimed to investigate the impact of TSPO knockout on RPE cellular metabolism by identifying the metabolic differences between wildtype and knockout RPE cells, with or without treatment with oxidized low density lipoprotein (oxLDL). Using liquid chromatography mass spectrometry (LC/MS), we differentiated several metabolic pathways among wildtype and knockout cells. Lipids amongst other intracellular metabolites were the most influenced by loss of TSPO and/or oxLDL treatment. Glucose, amino acid and nucleotide metabolism was also affected. TSPO deletion led to up-regulation of fatty acids and glycerophospholipids, which in turn possibly affected the cell membrane fluidity and stability. Higher levels of glutathione disulphide (GSSG) were found in TSPO knockout RPE cells, suggesting TSPO regulates mitochondrial-mediated oxidative stress. These data provide biochemical insights into TSPO-associated function in RPE cells and may shed light on disease mechanisms in AMD.

TAK1 is involved in the autophagy process in retinal pigment epithelial cells

2016 ◽  
Vol 94 (2) ◽  
pp. 188-196 ◽  
Author(s):  
Yaron A. Green ◽  
Keren Ben-Yaakov ◽  
Orit Adir ◽  
Ayala Pollack ◽  
Zeev Dvashi
Keyword(s):  
Oxidative Stress ◽  
Retinal Pigment Epithelial ◽  
Transforming Growth Factor ◽  
Retinal Pigment ◽  
Specific Inhibitor ◽  
Retinal Pigment Epithelial Cells ◽  
Age Related Macular Degeneration ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Age Related

Autophagy is an evolutionarily conserved mechanism for degrading long-lived or malfunctioning proteins and organelles, such as those resulting from oxidative stress. Several publications have demonstrated the importance of the autophagy process in the pathophysiology of dry age-related macular degeneration (AMD). Still, the mechanism underlying this process and its involvement in dry AMD are not fully characterized. Investigating the autophagy process in retinal pigment epithelial (RPE) cells, we identified transforming growth factor β activated kinase 1 (TAK1) as a key player in the process. We found increased TAK1 phosphorylation in ARPE-19 and D407 cells treated with different inducers of autophagy, such as oxidative stress and rapamycin. Moreover, utilizing TAK1 specific inhibitor prior to oxidative stress or rapamycin treatment, we found significant reduction in LC3A/B-II expression. These results point at the involvement of TAK1 in the regulation of autophagy in RPE cells. This study suggests that aberrant activity of this kinase impairs autophagy and subsequently leads to alterations in the vitality of RPE cells. Proper activity of TAK1 may be essential for efficient autophagy, and crucial for the ability of RPE cells to respond to stress and dispose of damaged organelles, thus preventing or delaying retinal pathologies.

scholarly journals Effects of FTMT Expression by Retinal Pigment Epithelial Cells on Features of Angiogenesis

2020 ◽  
Vol 21 (10) ◽  
pp. 3635
Author(s):  
Undral Buyandelger ◽  
Douglas G. Walker ◽  
Daijiro Yanagisawa ◽  
Toshifumi Morimura ◽  
Ikuo Tooyama
Keyword(s):  
Proinflammatory Cytokines ◽  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Angiogenic Factors ◽  
Retinal Pigment Epithelial Cells ◽  
Age Related Macular Degeneration ◽  
Pathological Feature ◽  
Cellular Models ◽  
Pigment Epithelial ◽  
Age Related

Aberrant angiogenesis is a pathological feature of a number of diseases and arises from the uncoordinated expression of angiogenic factors as response to different cellular stresses. Age-related macular degeneration (AMD), a leading cause of vision loss, can result from pathological angiogenesis. As a mutation in the mitochondrial ferritin (FTMT) gene has been associated with AMD, its possible role in modulating angiogenic factors and angiogenesis was investigated. FTMT is an iron-sequestering protein primarily expressed in metabolically active cells and tissues with high oxygen demand, including retina. In this study, we utilized the human retinal pigment epithelial cell line ARPE-19, both as undifferentiated and differentiated cells. The effects of proinflammatory cytokines, FTMT knockdown, and transient and stable overexpression of FTMT were investigated on expression of pro-angiogenic vascular endothelial growth factor (VEGF) and anti-angiogenic pigment epithelial-derived factor (PEDF). Proinflammatory cytokines induced FTMT and VEGF expression, while NF-κB inhibition significantly reduced FTMT expression. VEGF protein and mRNA expression were significantly increased in FTMT-silenced ARPE-19 cells. Using an in vitro angiogenesis assay with endothelial cells, we showed that conditioned media from FTMT-overexpressing cells had significant antiangiogenic effects. Collectively, our findings indicate that increased levels of FTMT inhibit angiogenesis, possibly by reducing levels of VEGF and increasing PEDF expression. The cellular models developed can be used to investigate if increased FTMT may be protective in angiogenic diseases, such as AMD.

scholarly journals Protective effects of delphinidin against H2O2–induced oxidative injuries in human retinal pigment epithelial cells

2019 ◽  
Vol 39 (8) ◽  
Author(s):  
Timin Ni ◽  
Wanju Yang ◽  
Yiqiao Xing
Keyword(s):  
Oxidative Stress ◽  
Protein Expression ◽  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
Age Related Macular Degeneration ◽  
Ros Generation ◽  
Dependent Manner ◽  
Pigment Epithelial ◽  
Age Related

Abstract Age-related macular degeneration (AMD) is now one of the leading causes of blindness in the elderly population and oxidative stress-induced damage to retinal pigment epithelial (RPE) cells occurs as part of the pathogenesis of AMD. In the present study, we evaluated the protective effect of delphinidin (2-(3,4,5-trihydroxyphenyl) chromenylium-3,5,7-triol) against hydrogen peroxide (H2O2)-induced toxicity in human ARPE-19 cells and its molecular mechanism. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and flow cytometry demonstrated that pretreatment of ARPE-19 cells with delphinidin (25, 50, and 100 μg/ml) significantly increased cell viability and reduced the apoptosis from H2O2 (0.5 mM)-induced oxidative stress in a concentration-dependent manner, which was achieved by the inhibition of Bax, cytochrome c, and caspase-3 protein expression and enhancement of Bcl-2 protein. The same tendency was observed in ARPE-19 cells pre-treated with 15 mM of N-acetylcysteine (NAC) before the addition of H2O2. Furthermore, pre-incubation of ARPE-19 cells with delphinidin markedly inhibited the intracellular reactive oxygen species (ROS) generation and Nox1 protein expression induced by H2O2. Moreover, the decreased antioxidant enzymes activities of superoxide dismutase (SOD), catalase (CAT), and glutathione-peroxidase (GSH-PX) and elevated (MDA) level in H2O2-treated cells were reversed to the normal standard by the addition of delphinidin, which was regulated by increasing nuclear Nrf2 protein expression in ARPE-19 cells. Our results suggest that delphinidin effectively protects human ARPE-19 cells from H2O2-induced oxidative damage via anti-apoptotic and antioxidant effects.

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