NR ATFX
AU Gahali-Sass,I.; Rouvinski,A.; Metzer,E.; Taraboulos,A.
TI Prions and raft lipids: cholesterol analogs reduce PrPsc in ScN2a cells
QU International Conference - Prion 2005: Between fundamentals and society's needs - 19.10.-21.10.2005, Congress Center Düsseldorf - Oral sessions ORAL-28
PT Konferenz-Vortrag
AB The metabolism and pathogenesis of prions appears to be associated with rafts, probably because both PrP isoforms are GPI-anchored. Rafts are membrane domains enriched with cholesterol and with (saturated) sphingolipids. Studies with liposomes have indicated that natural sterols differ widely in their propensity to form raft-like domains (Xu et al., J Biol Chem. 2001; 276:33540-6). We have investigated the effect of several cholesterol analogs on PrPsc. Cholesterol sulfate (CholSO4) is the major sulfated sterol in the human circulation (2-3µg/ml in adult serum). Treating ScN2a cells with 3-7.5µg/ml CholSO4 reduced PrPsc in a dose- and time-dependent way. In contrast, PrPc was slightly increased, but the internalization of cell surface PrPc was delayed. Thin layer chromatography showed that CholSO4 associated with cell membranes (ca 5µg CholSO4/1.5x107 cells). Density flotation of raft residents and cell surface patching of PrPc suggested that rafts were changed only slightly by the CholSO4 treatment. In contrast, lipids typically associated with rafts were dramatically changed. In particular, free cholesterol decreased by 30%, and the raft sphingolipid GM1 virtually disappeared after a 5 days treatment with 7.5µg/ml CholSO4. Adding bovine brain gangliosides to the cell medium together with CholSO4 repleted GM1 and partially prevented the PrPsc decrease. Dehydroepiandrosterone, a neurosteroid, also reduced PrPsc but dramatically increased GM1 and cholesterol. These results reinforce the idea that PrPsc metabolism is functionally associated with raft lipids. Additional data on prions and raft lipids, and results from bioassays will be presented.
AD I.Gahali-Sass, A.Rouvinski, E.Metzer, A.Taraboulos, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
SP englisch
PO Deutschland