NR ARVF
AU Qiu,Y.; Nixon,R.; Mobley,W.B.; Prusiner,S.B.; DeArmond,S.J.
TI Abnormalities of the plasma-membrane and endocytosis in prion- infected cell-lines
QU Journal of Neuropathology and Experimental Neurology 1996; 55(5): 635 Nr. 122
PT Meeting Abstract
AB We previously reported a decrease in plasma membrane fluidity in scrapie infected N2a (ScN2a) cells as compared to uninfectcd (N2a) cells which correlated with decreased bradykinin (Bk) receptor affinity for its ligand and decreased Bk-stimulated IP3 and Ca responses. We postulated that the change in membrane fluidity in scrapie was due to disruption of normal endocytic-plasma membrane recycling pathways. To test this hypothesis, we compared the rates of fluid phase endocytosis of horseradish peroxidase (HRP) in two scrapie (Sc)-infected cell lines relative to their unifected counterparts: N2a vs. ScN2a cells and GT-1-Trk9 vs. ScGT-1-Trk9 cells. The amounts of HRP uptake were determined by biochemical and cytochemical methods. The rate of uptake at 37° was compared to that at 4°. Biochemical measurement of total HRP activity after 10 min showed a statistically significant 15-25% increase in the rate of HRP uptake in the scrapie infected cell lines (p<0.001 covariant analysis). There was little or no exocytosis of the HRP into the medium over a 36 hr period; rather, internalized HRP was slowly degraded over that time period. The uptake and cellular distribution of HRP was determined by hiochemical detection of HRP with diaminobenzidine at 5, 10,30 and 60 min. Scrapie infected cells contained more and coarser granular deposits of HRP than did uninfected cells consistent with an increased rate of fluid phase endocytosis. In addition, fewer normal cells accumulated HRP than did scrapie-infected cells, particularly at the earlier time points. These findings raise the possibility that conversion of PrPc to PrPsc alters the trafficking of lipids and proteins in scrapie infected cells which, secondarily, alters plasma membrane fluidity and function.
AD University of California, School of Medicine, San Francisco, CA 94143-0506
ZR 0
SP englisch
OR Prion-Krankheiten 7