Sphingosylphosphorylcholine induces mitochondria-mediated apoptosis in neuro 2a cells: Involvement of protein kinase C

We demonstrate that sphingosylphosphorylcholine-mediated cell death involves the activation of different protein kinase Cisozymes in different manners. Treating cells with sphingosylphosphorylcholine resulted in activation of protein kinase C δ, which is necessary, together with elevation of Ca2+, for sphingosylphosphorylcholine-induced apoptosis. A rapid translocation from cytosol to membrane, and a proteolytic protein kinase C δ cleavage was found, probably due to activation of caspase-3, to give a catalytically active fragment involved in cellular apoptosis. Moreover, sphingosylphosphorylcholine also induced translocation of protein kinase C ζ, resulting in an anti-apoptotic effect. To explore whether a mitochondrial pathway is involved in sphingosylphosphorylcholine-induced apoptosis, we analyzed the effect of sphingosylphosphorylcholine on cytochrome c release and caspase-3 activity. We must point out that the sphingolipid caused an increase of cytochrome c release from mitochondria to cytosol concomitantly with an increase of caspase-3 activity. Furthermore, a translocation of Bax was found, after sphingosylphosphorylcholine treatment.