Workshop 2: Approaches for Studying the Biological Roles of Sphingolipids. Probing apoptosis during neuronal development with novel ceramide analogs

Abstract

Lipid analysis of gestational day E14.5 mouse brain revealed elevation of ceramide to a tissue concentration that induced apoptosis when added to the medium of neuroprogenitor cells grown in cell culture. Elevation of ceramide was coincident with the first appearance of β‐series complex gangliosides (BCGs). Expression of BCGs by stable transfection of murine neuroblastoma (F‐11) cells with sialyltransferase‐II (ST2) resulted in a 70% reduction of apoptosis that was induced with the novel ceramide analog (NCA) N‐oleoyl serinol (S18). This was most likely due to an 80% reduced expression of prostate apoptotis response‐4 (PAR‐4). PAR‐4 expression and apoptosis were restored by preincubation of ST2‐transfected cells with N‐butyl deoxinojirimycin (NB‐DNJ) or PD98059, two inhibitors of ganglioside biosynthesis or p42/44 MAPK‐kinase, respectively. In sections of day E14.5 mouse brain, the intermediate zone showed intensive staining for complex gangliosides, but only low staining for apoptosis (TUNEL) and PAR‐4. Apoptosis and PAR‐4 expression, however, were elevated in the ventricular zone, which only weakly stained for complex gangliosides. Complex gangliosides may thus activate a cell survival mechanism that selectively protects developing neurons against ceramide‐induced apoptosis by up‐regulation of MAPK and reduction of PAR‐4 expression. NCAs may be useful to analyse the molecular mechanisms that underlie or counteract ceramide‐induced apoptosis during neuronal development.Acknowledgements: Supported by grants MH61934‐04 (to E.B.) and NS11853 (to R.K.Y.).