PrP Knockout Cells Expressing Transmembrane PrP Resist Prion Infection

Area of Science:

• Neuroscience
• Biochemistry
• Molecular Biology

Background:

• Prion diseases involve misfolding of the prion protein (PrP^C) into infectious PrP^res.
• Glycosylphosphatidylinositol (GPI) anchoring directs PrP^C to membrane rafts, influencing misfolding and propagation.
• The role of raft localization in prion conversion remains incompletely understood.

Purpose of the Study:

• To investigate the necessity of GPI anchoring and raft localization for prion propagation.
• To determine if transmembrane-anchored PrP^C can convert to PrP^res under specific conditions.
• To utilize a novel cell culture model (NpL2 cells) for studying transmissible spongiform encephalopathy (TSE) infection.

Main Methods:

• Expression of PrP^C with either a GPI anchor or a nonraft transmembrane sequence in PrP knockout NpL2 cells.
• Infection of these cells with various prion strains and biochemical states of PrP^res (brain microsomes, purified fibrils).
• Assessment of PrP^res propagation and conversion in relation to PrP^C anchor type and localization.

Main Results:

• Only GPI-anchored PrP^C supported persistent PrP^res propagation.
• Transmembrane-anchored PrP^C did not support prion propagation, even when exposed to exogenous PrP^res.
• NpL2 cells provided a suitable model for studying prion infection dynamics.

Conclusions:

• GPI anchor-directed association of PrP^C with membrane rafts is essential for persistent PrP^res propagation in cell culture.
• Raft microdomains serve as critical sites for prion conversion.
• These findings highlight the importance of membrane microenvironment in prion pathogenesis.