Prion protein aggregation reverted by low temperature in transfected cells carrying a prion protein gene mutation

Prion diseases are characterized by the conversion of the normal cellular prion protein (PrPC), a glycoprotein that is anchored to the cell membrane by a glycosylphosphatidylinositol moiety, into an isoform that is protease-resistant (PrPres) and pathogenic. In inherited prion diseases, mutations in the prion protein (PrPM) engender the conversion of PrPM into PrPres. We developed a cell model of Gerstmann-Sträussler-Scheinker disease, a neurodegenerative condition characterized by PrPM-containing amyloid deposits and neuronal loss, by expressing the Gerstmann-Sträussler-Scheinker haplotype Q217R-129V in human neuroblastoma cells. By comparison to PrPC, this genotype results in the following alterations of PrPM: 1) expression of an aberrant form lacking the glycosylphosphatidylinositol anchor, 2) increased aggregation and protease resistance, and 3) impaired transport to the cell surface. Most of these alterations are temperature-sensitive, indicating that they are due to misfolding of PrPM.