Molecular Medicine Gene Silencing of the Mitochondrial Adaptor p66Shc Suppresses Vascular Hyperglycemic Memory in Diabetes

Rationale: Hyperglycemic memory may explain why intensive glucose control has failed to improve cardiovas-cular outcomes in patients with diabetes. Indeed, hyperglycemia promotes vascular dysfunction even after glucose normalization. However, the molecular mechanisms of this phenomenon remain to be elucidated. Objective: The present study investigated the role of mitochondrial adaptor p66Shc in this setting. Methods and Results: In human aortic endothelial cells (HAECs) exposed to high glucose and aortas of diabetic mice, activation of p66Shc by protein kinase C II (PKCII) persisted after returning to normoglycemia. Persistent p66Shc upregulation and mitochondrial translocation were associated with continued reactive oxygen species (ROS) production, reduced nitric oxide bioavailability, and apoptosis. We show that p66Shc gene overexpression was epigenetically regulated by promoter CpG hypomethylation and general control nondere-pressible 5–induced histone 3 acetylation. Furthermore, p66Shc-derived ROS production maintained PKCII upregulation and PKCII-dependent inhibitory phosphorylation of endothelial nitric oxide synthase at Thr-495, leading to a detrimental vicious cycle despite restoration of normoglycemia. Moreover, p66Shc activation accounted for the persistent elevation of the advanced glycated end product precursor methylglyoxal. In vitro and in vivo gene silencing of p66Shc, performed at the time of glucose normalization, blunted ROS production, restored endothelium-dependent vasorelaxation, and attenuated apoptosis by limiting cytochrome c release