Hyperoxia induces retinal vascular endothelial cell apoptosis through formation of peroxynitrite.
Hyperoxia exposure induces capillary endothelial cell apoptosis in the developing retina, leading to vaso-obliteration followed by proliferative retinopathy. Previous in vivo studies have shown that endothelial nitric oxide synthase (NOS3) and peroxynitrite are important mediators of the vaso-obliteration. Now we have investigated the relationship between hyperoxia, NOS3, peroxynitrite, and endothelial cell apoptosis by in vitro experiments using bovine retinal endothelial cells (BREC). We found that BREC exposed to 40% oxygen (hyperoxia) for 48 h underwent apoptosis associated with activation of caspase-3 and cleavage of the caspase substrate poly(ADP-ribose) polymerase. Hyperoxia-induced apoptosis was associated with increased formation of nitric oxide, peroxynitrite, and superoxide anion and was blocked by treatment with uric acid, nitro-L-arginine methyl ester, or superoxide dismutase. Analyses of the phosphatidylinositol 3-kinase/Akt kinase survival pathway in cells directly treated with peroxynitrite revealed inhibition of VEGF- and basic FGF-induced activation of Akt kinase. These results suggest that hyperoxia-induced formation of peroxynitrite induces BREC apoptosis by crippling key survival pathways and that blocking peroxynitrite formation prevents apoptosis. These data may have important clinical implications for infants at risk of retinopathy of prematurity.
Department of Cellular Biology and Anatomy, and Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912-2500, USA.
Xiaolin
X
Gu
Azza B
AB
El-Remessy
Steven E
SE
Brooks
Mohamed
M
Al-Shabrawey
Nai-Tsi
NT
Tsai
Ruth B
RB
Caldwell
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D018496:Hyperoxia / Q000378:metabolism / Q000473:pathology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D010100:Oxygen / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012171:Retinal Vessels / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction / Q000502:physiology; D013481:Superoxides / Q000378:metabolism
D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D010100:Oxygen; D030421:Peroxynitrous Acid; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D013481:Superoxides