Lipid rafts mediate H2O2 prosurvival effects in cultured endothelial cells.
Reactive oxygen species (ROS) generated during pathological events, such as inflammation and ischemia-reperfusion, activates both proapoptotic and antiapoptotic signaling programs in endothelial cells. Because cholesterol-rich, plasma membrane rafts serve as platforms for organizing and integrating signaling transduction processes, we asked whether these membrane regions play a mechanistic role in H2O2-induced responses. Bovine aortic endothelial cell cultures exposed to a 500-microM bolus of H2O2 showed progressive activation of caspase 3 and an increase in the number of TUNEL-positive cells. Pretreatment with either wortmannin or PD 098059 heightened these apoptotic responses, demonstrating that both PI3 kinase/Akt and ERK1/2 serve as signaling mediators to alleviate H2O2 cytotoxic effects. To investigate the role of lipid rafts in these signaling processes, endothelial cells were pretreated with methyl-beta-cyclodextrin (CD) or filipin to ablate raft structures. H2O2-induced phosphorylation of Akt and ERK 1/2 was attenuated, while caspase 3 and the number of TUNEL positive cells was enhanced in CD-pretreated cells exposed to H2O2. Reconstitution of raft domains restored H2O2-induced Akt and ERK1/2 phosphorylation, which was concomitant with reduction of caspase 3 activation and DNA fragmentation. Taken together, our findings suggest that plasma membrane compartments rich in cholesterol participate in signal transduction pathways activated by oxidative stress.
Yang
Baohua
B
Cardiovascular Research Center and Department of Anatomy and Cell Biology, Temple University School of Medicine, 3420 North Broad St., MRB826, Philadelphia, Pennsylvania 19140, USA.
Oo
Tin N
TN
Rizzo
Victor
V
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001011:Aorta; D017209:Apoptosis / Q000187:drug effects; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D020287:In Situ Nick-End Labeling; D021962:Membrane Microdomains / Q000502:physiology*; D010766:Phosphorylation; D017382:Reactive Oxygen Species; D000077191:Wortmannin
D000730:Androstadienes; D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D000077191:Wortmannin