Supplementation of Endothelial Cells with Mitochondria-targeted Antioxidants Inhibit Peroxide-induced Mitochondrial Iron Uptake, Oxidative Damage, and Apoptosis

Abstract

The mitochondria-targeted drugs mitoquinone (Mito-Q) and mitovitamin E (MitoVit-E) are a new class of antioxidants containing the triphenylphosphonium cation moiety that facilitates drug accumulation in mitochondria. In this study, Mito-Q (ubiquinone attached to a triphenylphosphonium cation) and MitoVit-E (vitamin E attached to a triphenylphosphonium cation) were used. The aim of this study was to test the hypothesis that mitochondria-targeted antioxidants inhibit peroxide-induced oxidative stress and apoptosis in bovine aortic endothelial cells (BAEC) through enhanced scavenging of mitochondrial reactive oxygen species, thereby blocking reactive oxygen species-induced transferrin receptor (TfR)-mediated iron uptake into mitochondria. Glucose/glucose oxidase-induced oxidative stress in BAECs was monitored by oxidation of dichlorodihydrofluorescein that was catalyzed by both intracellular H 2 O 2 and transferrin iron transported into cells. Pretreatment of BAECs with Mito-Q (1 M) and MitoVit-E (1 M) but not untargeted antioxidants (e.g. vitamin E) significantly abrogated H 2 O 2 -and lipid peroxide-induced 2 ,7 -dichlorofluorescein fluorescence and protein oxidation. Mitochondria-targeted antioxidants inhibit cytochrome c release, caspase-3 activation, and DNA fragmentation. Mito-Q and MitoVit-E inhibited H 2 O 2 -and lipid peroxide-induced inactivation of complex I and aconitase, TfR overexpression, and mitochondrial uptake of 55 Fe, while restoring the mitochondrial membrane potential and proteasomal activity. We conclude that Mito-Q or MitoVit-E supplementation of endothelial cells mitigates peroxide-mediated oxidant stress and maintains proteasomal function, resulting in the overall inhibition of TfR-dependent iron uptake and apoptosis.

Reactive Oxygen and Targeted Antioxidant Administration in Endothelial Cell Mitochondria

“…Mitochondria-targeted antioxidants protected Friedreich ataxia fibroblasts, in which glutathione synthesis was blocked, from oxidative stress (24), and mitoQ reduced telomere shortening in fibroblasts exposed to oxidative stress (25). In bovine aortic endothelial (BAE) cells, mitoQ reduced oxidative damage in cells stressed by 25 mM glucose and glucose oxidase (26). Moreover, mitoQ also reduced ROS and ERK2 activation in endothelial cells after hypoxic stress (27).…”

Complex I Dysfunction and Tolerance to Nitroglycerin

“…30 The active antioxidant form of MQ is the reduced ubiquinol form, which is regenerated by the electron transport chain, and selectively blocks mitochondrial oxidative damage by detoxifying ROS. 16,17 This and other mitochondrial-targeted antioxidants have been shown to protect this organelle from oxidative stress in isolated cells 32 and living tissues 20 in hypoxia, 26 apoptosis, 29 and cancer. 18 In our experiments, continuous pretreatment with GTN produced a substantial reduction in its vasorelaxant effects of GTN when administered acutely, but not in those of acute DETA-NO.…”

Mitochondrial Superoxide Production and Nuclear Factor Erythroid 2-Related Factor 2 Activation in p75 Neurotrophin Receptor-Induced Motor Neuron Apoptosis

“…the nontargeted antioxidants and particularly effective in preventing cell death induced by oxidative mitochondrial damage in vitro and in vivo (Kelso et al, 2001;Jauslin et al, 2003;Dhanasekaran et al, 2004Dhanasekaran et al, , 2005Adlam et al, 2005). Moreover, mitoQ has been shown to cross the blood-brain barrier and thus could be particularly useful to prevent mitochondrial oxidative damage and neuronal death induced by NGF/ p75 NTR -signaling in vivo.…”