Abstract 16505: Reprogramming Epigenetic Changes Blunts p66Shc-induced Vascular Dysfunction In Experimental and Human Obesity: Insights for Mechanisms-Based Therapeutic Strategies
Introduction: Epigenetic signatures may represent key modulators of oxidative stress in patients with obesity. The mitochondrial adaptor p66Shc is a major source of reactive oxygen species (ROS) in the vasculature.
Hypothesis: The present study was designed to investigate whether epigenetic regulation of p66Shc mediates vascular dysfunction in human and experimental obesity.
Methods: Visceral fat arteries (VFA) were isolated from 10 obese and 10 age-matched healthy subjects. To characterize the role of p66Shc, genetically obese mice (leptin deficient, LepOb/Obp66WT) were crossed with p66KO to generate double-mutant mice (LepOb/Obp66KO). Organ chamber experiments were performed to assess endothelium-dependent relaxations to acetylcholine (Ach, 10-9-10-4 mol/L). Mitochondrial superoxide anion (O2-) was assessed by ESR spectroscopy. mRNA and protein expression were assessed by real-time PCR and immunoblotting. Chromatin immunoprecipitation (ChIP) was performed to investigate epigenetic modifications on p66Shc promoter.
Results: Maximal endothelium-dependent relaxation was impaired in VFA from obese as compared with controls (64.9%±4.8 vs 93±2.9, p<0.01). p66Shc expression was increased in obese vessels (AU, 1.5±0.3 vs 0.7±0.2, p<0.01) and correlated with mitochondrial oxidative stress (r= 0.76, p<0.01) and endothelial dysfunction (r= -0.47, p<0.01). Demethylation and acetylation at lysine 9 of histone 3 (H3K9) were the main epigenetic changes found on p66Shc promoter of obese subjects. Interestingly, H3K9 methyl-writing and acetyl-erasing enzymes SUV39H1 and SRC-1 were dysregulated in these vessels. Consistently, LepOb/Obp66KO were protected against endothelial dysfunction and mitochondrial oxidative stress as compared with LepOb/Obp66WT. Overexpression of SUV39H1 and knockdown of SRC-1 abolished p66Shc upregulation and ROS generation in endothelial cells isolated from LepOb/Obp66WT.
Conclusions: Reversible epigenetic signatures on p66Shc promoter drive obesity-induced vascular disease. Reprogramming these modifications may attenuate vascular damage in obese individuals.
- © 2013 by American Heart Association, Inc.