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Travan Lukeland Gentles, Yan Levitsky, Kiera Fisher, Sandra S Hammer, Julia Busik, Elahé Crockett, Denis Proshlyakov; SIRT1 Activation and mitochondrial dynamics in Retinal Endothelial Cells. . Invest. Ophthalmol. Vis. Sci. 2020;61(7):729.
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© ARVO (1962-2015); The Authors (2016-present)
Diabetic Retinopathy (DR), a common complication of diabetes, is the leading cause of blindness among working-age adults. DR is ultimately a multifactorial disease caused by chronic hyperglycemia, dyslipidemia, and inflammation. Time restricted eating is a well-known intervention resulting in metabolic improvements and reduced incidence of diabetic complications; however, the mechanisms underlying metabolic shifts related to time restricted eating and metabolic disease complications are not well characterized. Sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, is activated during calorie restriction and results in changes to glucose and lipid metabolism. SIRT1 levels are decreased in diabetic retina thus, we hypothesize that fasting mimicking conditions (FMCs) will lead to increased levels of SIRT1 resulting in enhanced mitochondrial oxidation of carbon sources in retinal bovine endothelial cells.
Bovine retinal endothelial cells (BREC) were isolated and cultured according to previously established protocols. SIRT1 activation was induced pharmacologically by treatment with SRT1720 and serum deprivation in vitro (FMC). Gene expression was measured by qPCR and normalized to cyclophilin A expression. Cellular viability was measured by trypan blue exclusion assay and inferred from substrate-supported respiratory activity. Respiratory activity was measured using a custom-built microrespirometer.
BREC subjected to FMC showed a 3.04 ± 0.18-fold increase in SIRT1 expression (p<0.05, N=3). FMC resulted in a transient increase in respiratory activity from 50.7 ± 5.0 nM/sec (N = 3) in 10% serum conditions to 86.1 ± 10.3 nM/sec (N = 4) under FMC. After 24 hours of FMC, the respiratory activity was 55.5 ± 5.8 nM/sec (N = 3). There was no significant increase in BREC cell death under FMC for 24 hours compared to control (16.7 ± 4.3 % vs 5.7 ± 2.3 %, p>0.05).
Short term nutrient deprivation, such as intermittent fasting, leads to increased levels of SIRT1 and downstream metabolic adaptations. These changes promote glucose and lipid disposal with the potential to delay diabetes-induced retinopathy.
This is a 2020 ARVO Annual Meeting abstract.
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