Kinetics of expression of prion protein in uninfected and scrapie-infected N2a mouse neuroblastoma cells.

The scrapie prion protein, PrPSc, is formed from its isoform, the cellular PrPc. There is evidence available indicating that PrPSc is a necessary component of the infectious prion particle to cause a series of transmissible spongiform encephalopathies. We have used immunocytochemistry and RNA blotting techniques to investigate if infection with prions results in an increased PrP gene expression. For the experiments we used N2a cells which had been infected with prions (ScN2a cells). We demonstrated by confocal laser scanning microscopy that PrP-protein was present in the nucleus (predominantly in the nucleoli) of ScN2a cells. Analysis of the PrP-mRNA levels both in N2a- and in ScN2a cells using cDNA encoding PrPc revealed no marked alteration of the mRNA steady state level between the two cell strains. Likewise, in run-off experiments no changes in either PrP-specific transcription or in general transcriptional activity were found. The half-life of PrP-mRNA was found to be identical in both cell strains (7h). Taken together, these results show that PrPSc and/or PrPc is present in the nucleus (nucleoli) of ScN2a cells but does not display an effect on the expression of the PrP gene.