Nitric oxide stimulates chronic ceramide formation in glomerular endothelial cells.
Exposure of glomerular endothelial cells for 24 h to compounds releasing NO, including spermine-NO, MAHMA-NO, and S-nitroso-glutathione, results in a dose-dependent and delayed (after 24 h) increase in the lipid signaling molecule ceramide. This NO-induced stimulation occurs in a cGMP-independent fashion since the membrane-permeant cGMP analogue dibutyryl cGMP has no effect on chronic ceramide production. Short-term incubation of endothelial cells for 20 min reveals that NO and dibutyryl cGMP fail to stimulate an acute ceramide increase, whereas TNF-alpha, a well-known activator of sphingomyelinases, is able to acutely increase ceramide formation. Interestingly, N-oleoylethanolamine, an acidic ceramidase inhibitor, potentiates NO-induced chronic ceramide production, indicating that ceramide generation rather than ceramide metabolism is modulated by NO. Furthermore, NO-induced delayed ceramide formation is partially inhibited by the thiol-specific inhibitor iodoacetamide and the radical scavenger alpha-tocopherol, suggesting a regulatory role of thiol-containing enzymes and the involvement of a redox-sensitive mechanism. In addition, NO causes an increased DNA fragmentation in glomerular endothelial cells which is further enhanced by N-oleoylethanolamine and can be mimicked by exogenous ceramide. In summary, these results imply that ceramide represents an important mediator of NO-triggered chronic cell responses like apoptosis. Inhibition of ceramide synthesis may provide a new therapeutic approach to the treatment of pathological conditions involving increased NO formation.
Huwiler
A
A
Zentrum der Pharmakologie, Klinikum der Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, Frankfurt am Main, D-60590, Germany.
Dorsch
S
S
Briner
V A
VA
van den Bosch
H
H
Pfeilschifter
J
J
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002417:Cattle; D002478:Cells, Cultured; D002518:Ceramides / Q000096:biosynthesis*; D004727:Endothelium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004789:Enzyme Activation; D007678:Kidney Glomerulus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism
D002518:Ceramides; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D011493:Protein Kinase C