Interplay among H3K9-editing enzymes SUV39H1, JMJD2C and SRC-1 drives p66Shc transcription and vascular oxidative stress in obesity.

Aims Accumulation of reactive oxygen species (ROS) promotes vascular disease in obesity, but the underlying molecular mechanisms remain poorly understood. The adaptor p66(Shc) is emerging as a key molecule responsible for ROS generation and vascular damage. This study investigates whether epigenetic regulation of p66(Shc) contributes to obesity-related vascular disease. Methods and results ROS-driven endothelial dysfunction was observed in visceral fat arteries (VFAs) isolated from obese subjects when compared with normal weight controls. Gene profiling of chromatin-modifying enzymes in VFA revealed a significant dysregulation of methyltransferase SUV39H1 (fold change, -6.9, P<0.01), demethylase JMJD2C (fold change, 3.2, P<0.01), and acetyltransferase SRC-1 (fold change, 5.8, P<0.01) in obese vs. control VFA. These changes were associated with reduced di-(H3K9me2) and trimethylation (H3K9me3) as well as acetylation (H3K9ac) of histone 3 lysine 9 (H3K9) on p66(Shc) promoter. Reprogramming SUV39H1, JMJD2C, and SRC-1 in isolated endothelial cells as well as in aortas from obese mice (Lep(Ob/Ob)) suppressed p66(Shc)-derived ROS, restored nitric oxide levels, and rescued endothelial dysfunction. Consistently, in vivo editing of chromatin remodellers blunted obesity-related vascular p66(Shc) expression. We show that SUV39H1 is the upstream effector orchestrating JMJD2C/SRC-1 recruitment to p66(Shc) promoter. Indeed, SUV39H1 overexpression in obese mice erased H3K9-related changes on p66(Shc) promoter, while SUV39H1 genetic deletion in lean mice recapitulated obesity-induced H3K9 remodelling and p66(Shc) transcription. Conclusion These results uncover a novel epigenetic mechanism underlying endothelial dysfunction in obesity. Targeting SUV39H1 may attenuate oxidative transcriptional programmes and thus prevent vascular disease in obese individuals.