Characterization of intracellular dynamics of inoculated PrP-res and newly generated PrPSc during early stage prion infection in Neuro2a cells

- We analyzed cellular mechanisms involved in establishing prion infection.
- We established method for the distinction of newly generated PrPSc from inoculated PrPSc.
- Most of introduced PrPSc was transported to the endo-lysosomal pathway.
- Newly generated PrPSc was mainly detected in early and recycling endosomes.
- Transfer of PrPSc from endo-lysosomal to endocytic-recycling pathway initiates efficient PrPSc formation.

To clarify the cellular mechanisms for the establishment of prion infection, we analyzed the intracellular dynamics of inoculated and newly generated abnormal isoform of prion protein (PrPSc) in Neuro2a cells. Within 24 h after inoculation, the newly generated PrPSc was evident at the plasma membrane, in early endosomes, and in late endosomes, but this PrPSc was barely evident in lysosomes; in contrast, the majority of the inoculated PrPSc was evident in late endosomes and lysosomes. However, during the subsequent 48 h, the newly generated PrPSc increased remarkably in early endosomes and recycling endosomes. Overexpression of wild-type and mutant Rab proteins showed that membrane trafficking along not only the endocytic-recycling pathway but also the endo-lysosomal pathway is involved in de novo PrPSc generation. These results suggest that the trafficking of exogenously introduced PrPSc from the endo-lysosomal pathway to the endocytic-recycling pathway is important for the establishment of prion infection.