Interaction between Prion Protein and Aβ Amyloid Fibrils Revisited

Recent studies indicate that the pathogenesis of Alzheimer disease may be related to the interaction between prion protein (PrP) and certain oligomeric species of A beta peptide. However, the mechanism of this interaction remains unclear and controversial. Here we provide direct experimental evidence that, in addition to previously demonstrated binding to A beta oligomers, PrP also interacts with mature A beta fibrils. However, contrary to the recent claim that PrP causes fragmentation of A beta fibrils into oligomeric species, no evidence for such a disassembly could be detected in the present study. In contrast, our data indicate that the addition of PrP to preformed A beta fibrils results in a lateral association of individual fibrils into larger bundles. These findings have potentially important implications for understanding the mechanism by which PrP might impact A beta toxicity as well as for the emerging efforts to use PrP-derived compounds as inhibitors of A beta-induced neurodegeneration. [GRAPHICS]