Immunolocalisation of PrP(Sc) in scrapie-infected N2a mouse neuroblastoma cells by light and electron microscopy.
Eur J Cell Biol. 2008 Sep 30;
Authors: Veith NM, Plattner H, Stuermer CA, Schulz-Schaeffer WJ, Bürkle A
The causative agent of transmissible spongiform encephalopathies (TSE) is PrP(Sc), an infectious, misfolded isoform of the cellular prion protein (PrP(C)). The localisation and trafficking of PrP(Sc) and sites of conversion from PrP(C) to PrP(Sc) are under debate, particularly since most published work did not discriminate between PrP(C) and PrP(Sc). Here we describe the localisation of PrP(C) and PrP(Sc) in a scrapie-infected neuroblastoma cell line, ScN2a, by light and electron microscopic immunolocalisation. After eliminating PrP(C) with proteinase K, PrP(Sc) was detected at the plasma membrane, endocytosed via clathrin-coated pits and delivered to early endosomes. Finally, PrP(Sc) was detected in late endosomes/lysosomes. As we detected PrP(Sc) at the cell surface, in early endosomes and in late endosomes/lysosomes, i.e. locations where PrP(C) is also present, our data imply that the conversion process could take place at the plasma membrane and/or along the endocytic pathway. Finally, we observed the release of PrP(C)/PrP(Sc) via exocytotic pathways, i.e. via exosomes and as an opaque electron-dense mass which may represent a mechanism of intercellular spreading of infectious prions.
PMID: 18834644 [PubMed - as supplied by publisher]