Superoxide potently induces ceramide formation in glomerular endothelial cells.
Recent evidence suggests that the sphingolipid-derived second messenger ceramide and oxidative stress are intimately involved in apoptosis induction. Here we report that exposure of microcapillary glomerular endothelial cells to superoxide-generating substances, including hypoxanthine/xanthine oxidase and the redox cyclers DMNQ and menadione results in a dose-dependent and delayed increase in the lipid signaling molecule ceramide. Long-term incubation of endothelial cells for 2-30 h with either DMNQ or hypoxanthine/xanthine oxidase leads to a continuous increase in ceramide levels. In contrast, short-term stimulation for 1 min up to 1 h had no effect on ceramide formation. The DMNQ-induced delayed ceramide formation is dose-dependently inhibited by reduced glutathione, whereas oxidized glutathione was without effect. Furthermore, N-acetylcysteine completely blocks DMNQ-induced ceramide formation. All superoxide-generating substances were found to dose-dependently trigger endothelial cell apoptosis. In addition, glutathione and N-acetylcysteine also prevented superoxide-induced apoptosis and implied that ceramide represents an important mediator of superoxide-triggered cell responses like apoptosis.
Huwiler
A
A
Pharmazentrum Frankfurt, Institute of Medical Microbiology, Klinikum der Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, Frankfurt am Main, D-60590, Germany.
Böddinghaus
B
B
Pautz
A
A
Dorsch
S
S
Franzen
R
R
Briner
V A
VA
Brade
V
V
Pfeilschifter
J
J
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002417:Cattle; D002478:Cells, Cultured; D002518:Ceramides / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005978:Glutathione / Q000494:pharmacology; D019271:Hypoxanthine / Q000378:metabolism / Q000494:pharmacology; D007678:Kidney Glomerulus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009285:Naphthoquinones / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism* / Q000494:pharmacology; D014812:Vitamin K / Q000494:pharmacology; D014969:Xanthine Oxidase / Q000378:metabolism / Q000494:pharmacology
D000975:Antioxidants; D002518:Ceramides; D009285:Naphthoquinones; D013481:Superoxides; D014812:Vitamin K; D019271:Hypoxanthine; C063002:2,3-dimethoxy-1,4-naphthoquinone; D014969:Xanthine Oxidase; D005978:Glutathione; D000111:Acetylcysteine