Abstract 14657: p66Shc Mediates SUMO2-Induced Endothelial Dysfunction and ROS Production

Abstract

Endothelial dysfunction is one of the earliest changes promoting vascular pathologies. Studies suggest that promoting sumoylation increases endothelial dysfunction and development of atherosclerotic plaque. We showed that overexpression of SUMO2 (one of the sumo isoforms) leads to impaired vasorelaxation. However, the molecular signaling is not well understood.P66Shc is an adaptor protein known to regulate vascular function. Studies in mice suggest that p66Shc impairs endothelial function via promoting oxidative stress. Mice with p66Shc knockout are protected against endothelial dysfunction due to hyperlipidemia, diabetes, and aging. Therefore, we asked if p66Shc mediates endothelial effects of SUMO2. We show that p66Shc is modified by SUMO2 and knockdown of p66Shc in endothelial cells inhibits SUMO2-induced reactive oxygen species production as well as inflammation. To identify the specific residue of p66Shc getting sumoylated, we generated recombinant p66Shc and SUMO2ylated it with a commercially available kit. Using mass spectroscopy, we identified that lysine-81 in CH2 domain of p66Shc is specifically modified by SUMO2. We also show that SUMO2-modificaiton of p66ShcK81 promotes oxidative activation (serine-36 phosphorylation) and mitochondrial translocation of p66Shc which are essential for ROS production. P66Shc non-sumoylatable at lysine 81 (p66ShcK81R) is resistant to SUMO2-induced serine-36 phosphorylation and mitochondrial translocation. To examine physiological significance of p66ShcK81-SUMO2, we generated a mouse model having knock in of p66ShcK81R. Using aortic rings from p66ShcK81R knock in and wild type mice, we show that overexpression of SUMO2 significantly impairs endothelium dependent relaxation in wild type mice aortic rings while aortic rings from p66ShcK81R knock are protected against it. Together, we demonstrate that SUMO2-p66Shc is a novel molecular signaling regulating vascular endothelial function.