NR AXRQ
AU Luhr,K.; Nordström,E.; Löw,P.; Kristensson,K.
TI Regulation of Cathepsin Activity Affects Accumulation of PrPsc in ScGT1-1 Cells
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Natural and Experimental Strains P02.39
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB
Background: During prion diseases, PrPsc accumulates as a partially processed protein, PrP 27-30 in infected cells. We have previously shown that inhibition of specific lysosomal proteases, cathepsin B and L, in GT1-1 cells infected with the RML strain of scrapie (ScGT1-1), increases the amount of PrPsc, indicating that these proteases are important for PrPsc degradation. Variations in the degradation rates and cleavage-mechanisms between different strains may affect the accumulation and distribution of the different strains in cells.
Objectives: We here ask the question whether cathepsins are involved in degradation of different prion strains and if the regulation of cathepsin activity can modify the cellular clearance of PrPsc.
Methods: We investigated if inhibition of specific cathepsins increases the amount of the prion strains RML, Me7 and 22L in the GT1-1 cells. Using Western immunoblotting we studied the effects on PrPsc in ScGT1-1 cells after serum starvation and reduction of glucose, as well as other treatment known to affect cathepsin activity in different cell types. Changes in cathepsin activities after these treatments were measured using cathepsin B- and L-specific fluorescent substrates.
Results: We have analyzed effects in ScGT1-1 cells after treatments affecting cathepsin activities and found that starvation for 48 hrs caused decreased levels of PrPsc of the RML strain. This decrease was blocked by co-incubation with specific inhibitors of cathepsin B (CA074Me) and cathepsin L (Z-Phe-Tyr-aldehyde) indicating that these cathepsins are important for the starvation-induced reduction of PrPsc in the ScGT1-1 cells. We have also investigated the effect of specific cathepsin inhibitors on the levels of PrPsc from different prion strains during treatments decreasing the amount of PrPsc in the cells.
Conclusions: We conclude that manipulations of cathepsin activity in prion-infected cells can affect the amount of accumulated PrPsc in the cells, leading to altered balances between the formation and the degradation of PrPsc. The identification of molecules regulating the amount of PrPsc in a cell are important for elucidating the mechanisms involved in potential clearance of PrPsc from prion infected cells.
This research was supported by EC grant StrainBarrier FOOD-CT-2006-023183, Stiftelsen Lars Hiertas minne and Loo och Hans Ostermans Stiftelse för geriatrisk forskning.
AD K. Luhr, E. Nordström, P. Löw, K. Kristensson, Karolinska Institutet, Neuroscience, Sweden
SP englisch
PO Schottland