Abstract 13770: Caveolin-1 is a Critical Determinant of Vascular Oxidative Stress
Reactive oxygen species (ROS) are implicated in the pathogenesis of many cardiovascular disease states. Caveolin-1 is a scaffolding/regulatory protein that interacts with diverse signaling molecules. Caveolin-1null mice have marked cardiovascular abnormalities, yet the molecular mechanisms are incompletely understood. We hypothesized that caveolin-1 regulates redox state in cardiovascular tissues. We found that plasma 8-isoprostanes levels were significantly higher in caveolin-1null mice compared to wild-type control mice (454 ± 44 vs. 319 ± 3 pg/ml, p<0.05). We performed tail vein injections in caveolin-1null and wild-type mice using a recombinant lentivirus expressing the hydrogen peroxide (H2O2) biosensor HyPer2; quantitative fluorescence imaging studies revealed significant increases in intracellular H2O2 in the endothelium of arterial preparations isolated from caveolin-1null mice (p<0.05 compared to wild type). siRNA-mediated caveolin-1 knockdown in cultured endothelial cells led to significant (p<0.05) increases both in intracellular and extracellular H2O2 levels (measured using the HyPer2 biosensor or the Amplex Red assay, respectively), associated with a marked decrease in the GSH/GSSG ratio. The mitochondrial inhibitor rotenone attenuated the increase in extracellular H2O2 levels seen after caveolin-1 knockdown, whereas the NADPH oxidase inhibitors apocynin and VAS-7820 had no effect. Cellular imaging of mitochondrial ROS production (assayed with MitoSox Red) and of mitochondrial membrane potential (measured using tetramethylrhodamine methyl ester) revealed marked increases after caveolin-1 knockdown, with no change in mitochondrial abundance (quantitated using MitoTracker Green). Importantly, 2-deoxy-D-glucose significantly attenuated the increase in mitochondrial ROS production seen after caveolin-1 knockdown, indicating that caveolin-1 may modulate oxidative stress through the regulation of glycolytic pathways. These findings establish that caveolin-1 plays a key role in the regulation of cellular and vascular oxidative stress, and suggest that caveolin-1-medulated pathways may represent novel targets for the amelioration of oxidative stress in cardiovascular disease states.
- © 2012 by American Heart Association, Inc.