NR AIUN
AU Naslavsky,N.; Shmeeda,H.; Friedlander,G.; Yanai,A.; Futerman,A.H.; Barenholz,Y.; Taraboulos,A.
TI Sphingolipid depletion increases formation of the scrapie prion protein in neuroblastoma cells infected with prions
QU The Journal of Biological Chemistry 1999 Jul 23; 274(30): 20763-71
IA http://www.jbc.org/cgi/content/full/274/30/20763
PT journal article
AB Sphingolipid-rich rafts play an essential role in the posttranslational (Borchelt, D. R., Scott, M., Taraboulos, A., Stahl, N., and Prusiner, S. B. (1990) J. Cell Biol. 110, 743-752)) formation of the scrapie prion protein PrPsc from its normal conformer PrPc (Taraboulos, A., Scott, M., Semenov, A., Avrahami, D., Laszlo, L., Prusiner, S. B., and Avraham, D. (1995) J. Cell Biol. 129, 121-132). We investigated the importance of sphingolipids in the metabolism of the PrP isoforms in scrapie-infected ScN2a cells. The ceramide synthase inhibitor fumonisin B(1) (FB(1)) reduced both sphingomyelin (SM) and ganglioside GM1 in cells by up to 50%, whereas PrPsc increased by 3-4-fold. Whereas FB(1) profoundly altered the cell lipid composition, the raft residents PrPc, PrPsc, caveolin 1, and GM1 remained insoluble in Triton X-100. Metabolic radiolabeling demonstrated that PrPc production was either unchanged or slightly reduced in FB(1)-treated cells, whereas PrPsc formation was augmented by 3-4-fold. To identify the sphingolipid species the decrease of which correlates with increased PrPsc, we used two other reagents. When cells were incubated with sphingomyelinase for 3 days, SM levels decreased, GM1 was unaltered, and PrPsc increased by 3-4-fold. In contrast, the glycosphingolipid inhibitor PDMP reduced PrPsc while increasing SM. Thus, PrPsc seems to correlate inversely with SM levels. The effects of SM depletion contrasted with those previously obtained with the cholesterol inhibitor lovastatin, which reduced PrPsc and removed it from detergent-insoluble complexes.
MH Animal; Mice; Neuroblastoma/*metabolism/virology; PrPsc Proteins/*metabolism; Prion Diseases/metabolism; Prions/*metabolism; Sphingolipids/*metabolism; Support, Non-U.S. Gov't; Support, U.S. Gov't, Non-P.H.S.; Tumor Cells, Cultured
AD Department of Molecular Biology, The Hebrew University-Hadassah Medical School, P. O. Box 12272, Jerusalem 91120, Israel.
SP englisch
PO USA