Abstract 482: IDH2 Deficiency Induces Oxidative Stress and Vascular Inflammation

Abstract

Isocitrate dehydrogenase 2 (IDH2) plays an essential role protecting cells against oxidative stress-induced damage. A deficiency in IDH2 leads to mitochondrial dysfunction and the production of reactive oxygen species (ROS) in cardiomyocytes and endothelial cells. However, the physiological function of IDH2 in vascular system is mostly unknown In this study, we investigated whether IDH2 knockdown causes mitochondrial dysfunction and vascular inflammation in vitro and in vivo . IDH2 knockdown decreased the expression of mitochondrial oxidative phosphorylation (OXPHOS) complexes I, II and III, which lead to increased mitochondrial superoxide. In addition, the levels of fission and fusion proteins (Mfn-1, OPA-1, and Drp-1) were significantly altered and MnSOD expression also was decreased by IDH2 knockdown. Furthermore, knockdown of IDH2 decreased eNOS phosphorylation and nitric oxide (NO) concentration in endothelial cells. Interestingly, treatment with Mito-TEMPO, a mitochondrial-specific superoxide scavenger, recovered mitochondrial fission-fusion imbalance and blunted mitochondrial superoxide production, and reduced the IDH2 knockdown-induced decrease in MnSOD expression, eNOS phosphorylation and NO production in endothelial cells. Endothelium-dependent vasorelaxation was impaired, and the concentration of bioavailable NO decreased in the aortic ring in IDH2 knockout mice. These findings suggest that IDH2 deficiency induces endothelial dysfunction through the induction of dynamic mitochondrial changes and impairment in vascular function. Key words: IDH2, mitochondria, endothelial cells, ROS