Mitochondria-specific transgenic overexpression of phospholipid hydroperoxide glutathione peroxidase (GPx4) attenuates ischemia/reperfusion-associated cardiac dysfunction
West Virginia University School of Medicine, Division of Exercise Physiology, and Center for Interdisciplinary Research in Cardiovascular Sciences, 1 Medical Center Drive, Morgantown, WV 26506, USA.Free Radical Biology and Medicine (Impact Factor: 5.74). 09/2008; 45(6):855-65. DOI: 10.1016/j.freeradbiomed.2008.06.021
Ischemia/reperfusion (I/R) injury elicits damage to mitochondria. Antioxidants provide protection from I/R-induced mitochondrial damage. The goal of this study was to determine the impact of mitochondria-specific overexpression of GPx4 (PHGPx) on cardiac function following I/R. Transgenic mice were created in which PHGPx was overexpressed solely in the mitochondrion (mPHGPx). MPHGPx and littermate control hearts were subjected to global no-flow ischemia (20 min) followed by reflow reperfusion (30, 60, and 90 min). Following I/R, mPHGPx hearts possessed significantly better rates of contraction, developed pressures, and peak-systolic pressures as compared to controls (P<0.05). No differences were observed in rates of relaxation or end-diastolic pressures. Lipid peroxidation was significantly lower in mitochondria from mPHGPx hearts as compared to controls, following I/R (P<0.05). Electron transport chain (ETC) complex I, III, and IV activities were significantly higher in mPHGPx hearts as compared to controls, following I/R (P<0.05). MPHGPx overexpression enhanced ETC complex I, III, and IV activities in subsarcolemmal mitochondria (SSM; P<0.05), and ETC complex I and III activities in interfibrillar mitochondria (IFM; P<0.05) following I/R. These results indicate that mitochondria-specific GPx4 overexpression protects cardiac contractile function and preserves ETC complex activities following I/R. These results provide further rationale for the use of mPHGPx as a therapeutic protectant.
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- "In support of this theory, both F2-IsoP production and accumulation of intercellular and secreted hydroperoxides were significantly decreased in GPx4-overexpressing mouse aortic endothelial cells compared with atherosclerotic cells( 33 ). When mitochondrial GPx4 was overexpressed in a mouse ischaemia–reperfusion model, researchers documented significantly increased cardiac function and decreased lipid peroxidation( 34 ). In another atherosclerosis model, ApoE−/– and GPx1 double knockout mice exhibited significantly increased atherosclerotic lesion development, suggesting that GPx1 may also play a role in disease progression( 88 ). "
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- "As expected in our high glucose exposed renal MECs, we found a significant reduction in complex I activity, with no apparent changes to the activities of complex III and IV. This is in accordance with the observations of others [35, 43–45]. Further, Lambert and Brand  have shown that high superoxide generation by the mitochondria requires inhibition of complex I activity. "
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