Serum deprivation increases ceramide levels and induces apoptosis in undifferentiated HN9.10e cells.
Sphingolipid metabolites have been involved in the regulation of proliferation, differentiation and apoptosis. While cellular mechanisms of these processes have been extensively analysed in the post-mitotic neurons, little is known about proliferating neuronal precursors. We have taken as a model of neuroblasts the embryonic hippocampal cell line HN9.10e. Apoptosis was induced by serum deprivation and by treatment with N-acetylsphingosine (C2-Cer), a membrane-permeant analogue of the second messenger ceramide. Following C2-Cer addition, cytochrome c was released from mitochondria, [Ca(2+)](i) and caspase-3-like activity increased. Both cytochrome c release and rise of [Ca(2+)](i) occurred before caspase-3 activation and nuclear condensation. The intracellular levels of ceramide peaked at 1h following the serum deprivation. These results indicate that the serum deprivation induces a rise in the intracellular ceramide level, and that increased ceramide concentration leads to calcium dysregulation and release of cytochrome c followed by caspase-3 activation. We show that cytochrome c is released without a loss of mitochondrial transmembrane potential.
Colombaioni
Laura
L
Institute of Neurophysiology of CNR, Pisa, Italy.
Frago
Laura M
LM
Varela-Nieto
Isabel
I
Pesi
Rossana
R
Garcia-Gil
Mercedes
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured / Q000187:drug effects; D002518:Ceramides / Q000096:biosynthesis*; D016895:Culture Media, Serum-Free / Q000494:pharmacology*; D003574:Cytochrome c Group / Q000032:analysis; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology
D002518:Ceramides; D016895:Culture Media, Serum-Free; D003574:Cytochrome c Group; C064769:N-acetylsphingosine; D009419:Nerve Tissue Proteins; D053148:Caspase 3; D020169:Caspases; D013110:Sphingosine; D002118:Calcium