The Unexposed Secrets of Prion Protein Oligomers.

According to the "protein-only" hypothesis, the misfolding and conversion of host-derived cellular prion protein (PrP(C)) into pathogenically misfolded PrP are believed to be the key procedure in the pathogenesis of prion diseases. Intermediate, soluble oligomeric prion protein (PrP) aggregates were considered a critical process for prion diseases. Several independent studies on PrP oligomers gained insights into oligomers' formation, biophysical and biochemical characteristics, structure conversion, and neurotoxicity. PrP oligomers are rich in β-sheet structure and slightly resistant to proteinase K digestion. PrP oligomers exhibited more neurotoxicity and induced neuronal apoptosis in vivo and/or in vitro. In this review, we summarized recent studies regarding PrP oligomers and the relationship between misfolded PrP aggregates and neuronal death in the course of prion diseases.