Inhibition of phosphatidylcholine synthesis precedes apoptosis induced by C2-ceramide: protection by exogenous phosphatidylcholine.
Cerebellar granule neurons in primary culture underwent apoptosis when exposed to C2-ceramide. Addition of exogenous phosphatidylcholine (PtdCho) resulted in a dose-dependent full prevention of neuronal death. Exogenous PtdCho also prevented apoptosis induced by farnesol, N-oleoylethanolamine, and sphingomyelinase, but did not prevent apoptosis induced after lowering the potassium concentration in the medium to non-depolarizing levels. Moreover, C2-ceramide inhibited labeling of [32P]PtdCho in cells incubated with [32P]orthophosphate, with the same potency to that causing apoptosis. Although cell viability did not decrease during the first few hours, inhibition of PtdCho synthesis was already patent after a 1 h exposure to C2-ceramide. Taken together, these results strongly suggest that inhibition of PtdCho synthesis constitutes one of the primary events by which C2-ceramide triggers apoptosis in cerebellar granule neurons.
Ramos
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Department of Physiology, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain.
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D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010713:Phosphatidylcholines / Q000096:biosynthesis* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*
C064769:N-acetylsphingosine; D018696:Neuroprotective Agents; D010713:Phosphatidylcholines; D013110:Sphingosine