title: Serum deprivation increases ceramide levels and induces apoptosis in undifferentiated HN9.10e cells.
abstract: 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.
authors.affiliation: Institute of Neurophysiology of CNR, Pisa, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Colombaioni
authors.forename: Laura M
authors.initials: LM
authors.lastname: Frago
authors.forename: Isabel
authors.initials: I
authors.lastname: Varela-Nieto
authors.forename: Rossana
authors.initials: R
authors.lastname: Pesi
authors.forename: Mercedes
authors.initials: M
authors.lastname: Garcia-Gil
mesh_terms: 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
chemical_list: 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