Host and transmissible spongiform encephalopathy agent strain control glycosylation of PrP

PrP is a host-encoded glycoprotein involved in the pathogenesis of transmissible spongiform encephalopathies (TSEs) or 'prion' diseases. The normal form of the protein (PrPC) is heavily but incompletely glycosylated; it shows structural diversity in three neuroanatomically distinct regions of the brain. No effect of TSE infection on PrPC glycosylation has been detected. TSE-specific forms of PrP (PrPSc) vary in their degree of glycosylation according to strain of TSE infectious agent. PrPSc also varies independently in the amount and pattern of glycosylation according to brain region. This diversity shows that the glycosylation of PrP is under both host- and TSE agent-specified control, probably within the biosynthetic pathway for protein N-glycosylation. These findings challenge assumptions that PrPSc is formed from the normal, mature form of PrPC but are compatible with a model in which the glycosylation phenotype of PrPSc is under the control of both host cellular factors and TSE agent-specified information.