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Lipid rafts mediate H 2 O 2 prosurvival effects in cultured endothelial cells
Author(s) -
Yang Baohua,
Oo Tin N.,
Rizzo Victor
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.05-5359fje
Subject(s) - lipid raft , microbiology and biotechnology , caveolae , wortmannin , signal transduction , protein kinase b , apoptosis , phosphorylation , pi3k/akt/mtor pathway , reactive oxygen species , chemistry , oxidative stress , biology , biochemistry
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 H 2 O 2 ‐induced responses. Bovine aortic endothelial cell cultures exposed to a 500‐µM bolus of H 2 O 2 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 H 2 O 2 cytotoxic effects. To investigate the role of lipid rafts in these signaling processes, endothelial cells were pretreated with methyl‐β‐cyclodextrin (CD) or filipin to ablate raft structures. H 2 O 2 ‐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 H 2 O 2 . Reconstitution of raft domains restored H 2 O 2 ‐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, B., Oo, T. N., and Rizzo, V. Lipid rafts mediate H 2 O 2 prosurvival effects in cultured endothelial cells. FASEB J. 20, E688–E697 (2006)