On the role of the cellular prion protein in the uptake and signaling of pathological aggregates in neurodegenerative diseases

Neurodegenerative disorders are associated with intra- or extra-cellular deposition of aggregates of misfolded insoluble proteins. These deposits composed of tau, amyloid-β or α-synuclein spread from cell to cell, in a prion-like manner. Novel evidence suggests that the circulating soluble oligomeric species of these misfolded proteins could play a major role in pathology, while insoluble aggregates would represent their protective less toxic counterparts. Recent convincing data support the proposition that the cellular prion protein, PrP(C), act as a toxicity-inducing receptor for amyloid-β oligomers. As a consequence, several studies focused their investigations to the role played by PrP(C) in binding other protein aggregates, such as tau and α-synuclein, for its possible common role in mediating toxic signalling. The biological relevance of PrP(C) as key ligand and potential mediator of toxicity for multiple proteinaceous aggregated species, prions or PrP(Sc) included, could lead to relevant therapeutic implications. Here we describe the structure of PrP(C) and the proposed interplay with its pathological counterpart PrP(Sc) and then we recapitulate the most recent findings regarding the role of PrP(C) in the interaction with aggregated forms of other neurodegeneration-associated proteins.