Abstract 9930: Exercise-Induced ATP7A, A Cu Transporter for SOD3, Restores Endothelial Dysfunction in Type2 Diabetes via Cysteine Oxidation of Protein Kinase G

Abstract

Background: Exercise training protects against type2 diabetes (T2D)-induced endothelial dysfunction which is mediated through eNOS uncoupling-induced O 2 -, but its underlying mechanisms are not fully understood. Cu transporter ATP7A is required for full activity of antioxidant Cu enzyme extracellular SOD (SOD3) that scavenges O 2 - to generate H 2 O 2 that has been proposed to function as a signaling molecule to mediate endothelium-dependent vasorelaxation (EDR) in T2D instead of nitric oxide (NO). However, role of ATP7A and its link with H 2 O 2 signaling in exercise-induced restoration of endothelial function in T2D is entirely unknown. Results: Here we show that ATP7A protein (49%), SOD3 activity (51%) and extracellular H 2 O 2 levels as well as EDR in blood vessels of high fat diet-induced T2D mice were significantly decreased compared to those of control C57Bl6 mice, which were restored by volunteer wheel exercise (2 weeks) or in T2D/ATP7A overexpressing mice. Of note, exercise-induced restoration of EDR in T2D mice was inhibited by PEG-catalase infusion or direct application of catalase to vessels, or in ATP7A dysfunctional ATP7A mut mice or T2D/SOD3 knockout (KO) mice, but not by eNOS inhibitor, L-NAME. This suggests that exercise-induced ATP7A-SOD3 axis-derived H 2 O 2 , but not eNOS/NO, plays a role in this effect. We then examined downstream targets of exercise-induced H 2 O 2 in blood vessels and found that protein kinase G (PKG)1α that is shown to be activated by exogenous H 2 O 2 via oxidation at Cys42 was sulfenylated (CysOH formed)(2.3-fold increase) in response to exercise in aorta of T2D, but not control, mice. This T2D-specific exercise-induced CysOH formaton of PKG1a in vascular tissue was inhibited by T2D/ ATP7A mut mice or T2D/SOD3 KO mice or PEG-catalase treatment. Functionally, “redox-dead” PKG1a Cys42Ser knock-in mutant mice blocked exercise-induced restoration of EDR in T2D, not control mice. Conclusion: Exercise-induced ATP7A promotes SOD3-mediated out-side in H 2 O 2 signaling, which contributes to restore EC dysfunction in T2D via PKG1α oxidation at Cys42.