P66Shc Mediates SUMO2-induced Endothelial Dysfunction

Abstract

Sumoylation is a post-translational modification that can regulate different physiological functions. Increased sumoylation, specifically conjugation of SUMO2/3 (small ubiquitin like modifier 2/3), is detrimental to vascular health. However, the molecular mechanism mediating this effect is poorly understood. Here, we demonstrate that SUMO2 modifies p66Shc, which impairs endothelial function. In endothelial cells, knockdown of p66Shc blunted SUMO2-induced increases in reactive oxygen species and inflammation. Using multiple approaches, we show that p66Shc is a direct target of SUMO2. Mass spectrometry identified that SUMO2 modified lysine-81 in the unique collagen homology-2 domain of p66Shc. SUMO2ylation of p66Shc increased phosphorylation at serine-36 (S36), causing it to translocate to the mitochondria, which are key steps regulating the oxidative function of p66Shc. Notably, sumoylation-deficient p66Shc (p66ShcK81R) was resistant to SUMO2-induced p66ShcS36 phosphorylation and mitochondrial translocation. Ingenuity pathway analysis showed that SUMO2ylation of p66ShcK81 regulated multiple pathways in endothelial cells, including Rac1-GTPase. Finally, to examine the physiological significance of this posttranslational modification in vivo, we generated p66ShcK81R knockin mice. Unlike wild-type mice, the aortic rings of p66ShcK81R knockin mice were resistant to SUMO2-induced endothelial dysfunction. Collectively, our work uncovers a posttranslational modification of redox protein p66Shc and identifies SUMO2-p66Shc signaling as a regulator of vascular endothelial function.