Abstract
The purpose of this study was to test the hypothesis whether Mito-carboxy proxyl (Mito-CP), a mitochondria-targeted nitroxide, inhibits peroxide-induced oxidative stress and apoptosis in bovine aortic endothelial cells (BAEC). Glucose/glucose oxidase (Glu/GO)-induced oxidative stress was monitored by dichlorodihydrofluorescein oxidation catalyzed by intracellular H(2)O(2) and transferrin receptor-mediated iron transported into cells. Pretreatment of BAECs with Mito-CP significantly diminished H(2)O(2)- and lipid peroxide-induced intracellular formation of dichlorofluorescene and protein oxidation. Electron paramagnetic resonance (EPR) studies confirmed the selective accumulation of Mito-CP into the mitochondria. Mito-CP inhibited the cytochrome c release and caspase-3 activation in cells treated with peroxides. Mito-CP inhibited both H(2)O(2)- and lipid peroxide-induced inactivation of complex I and aconitase, overexpression of transferrin receptor (TfR), and mitochondrial uptake of (55)Fe, while restoring the mitochondrial membrane potential and proteasomal activity. In contrast, the "untargeted" carboxy proxyl (CP) nitroxide probe did not protect the cells from peroxide-induced oxidative stress and apoptosis. However, both CP and Mito-CP inhibited superoxide-induced cytochrome c reduction to the same extent in a xanthine/xanthine oxidase system. We conclude that selective uptake of Mito-CP into the mitochondria is responsible for inhibiting peroxide-mediated Tf-Fe uptake and apoptosis and restoration of the proteasomal function.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Aconitate Hydratase / metabolism
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Animals
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Antioxidants / pharmacology
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Aorta / cytology
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Apoptosis
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Caspases / metabolism
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Catalysis
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Cattle
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Cell Survival
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Cyclic N-Oxides / pharmacology
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Cytochromes c / metabolism
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Cytosol / metabolism
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Electron Spin Resonance Spectroscopy
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Endothelial Cells / cytology
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Endothelium, Vascular / cytology
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Flow Cytometry
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Free Radicals
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Gas Chromatography-Mass Spectrometry
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Glucose Oxidase / metabolism
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Hydrogen Peroxide / chemistry
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Hydrogen Peroxide / pharmacology
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Iron / metabolism
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Lipid Peroxidation
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Lipids / chemistry
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Membrane Potentials
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Microscopy, Fluorescence
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Mitochondria / enzymology*
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Mitochondria / metabolism
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Models, Chemical
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Nitric Oxide / metabolism
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Organophosphorus Compounds / pharmacology
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Oxidative Stress
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Oxygen / metabolism
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Peroxides / pharmacology*
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Proteasome Endopeptidase Complex / chemistry
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Proteasome Endopeptidase Complex / metabolism
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Receptors, Transferrin / chemistry
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Receptors, Transferrin / metabolism
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Superoxide Dismutase / chemistry*
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Superoxides / chemistry
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Time Factors
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Transferrin / metabolism
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Xanthine / chemistry
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Xanthine Oxidase / metabolism
Substances
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Antioxidants
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Cyclic N-Oxides
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Free Radicals
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Lipids
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Organophosphorus Compounds
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Peroxides
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Receptors, Transferrin
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Transferrin
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mito-carboxy proxyl
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Superoxides
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Xanthine
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Nitric Oxide
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Cytochromes c
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Hydrogen Peroxide
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Iron
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Glucose Oxidase
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Superoxide Dismutase
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Xanthine Oxidase
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Caspases
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Proteasome Endopeptidase Complex
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ATP dependent 26S protease
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Aconitate Hydratase
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Oxygen