The scrapie prion protein is present in flotillin-1-positive vesicles in central- but not peripheral-derived neuronal cell lines

Transmissible prion diseases are fatal neurodegenerative diseases associated with the conversion of the normal host prion protein (PrPc) into an abnormal isoform (PrPSc) that accumulates in brain. This pathology affects neurons of the central nervous system whereas no clear toxic effect has been reported for peripheral neurons. We examined the subcellular distribution of PrPc and PrPSc in the scrapie-infected mouse neuronal cell lines GT1-7 and N2a, derived, respectively, from the central and peripheral nervous system. We observed that in both cell types, PrPc is present in the endocytic compartment, mainly in LAMP-1-positive late endosomes, but excluded from LYAAT-1-lysosomes. In contrast, PrPSc was distributed differently in the two cell lines. In infected N2a, PrPSc and PrPc had comparable distribution patterns. In infected GT1-7, PrPSc is present in an additional vesicular compartment which is flotillin-1-positive. The level of expression of flotillin-1 is higher in GT1-7 than in N2a cells, but no difference is observed between infected and noninfected cells. In Alzheimer's disease patients, it has been reported that flotillin-1 is abundant in brain areas containing the beta-amyloid protein, which accumulates in endosomal vesicles in primary neurons. We propose that the flotillin compartment could store aggregated proteins and play a role in these neurodegenerative pathologies.