Cytotoxicity of Prion Protein Peptide (PrP106–126) Differs in Mechanism from the Cytotoxic Activity of the Alzheimer's Disease Amyloid Peptide, Aβ25–35

The abnormal form of the prion protein (PrP^Sc), a synthetic prion protein peptide fragment (PrP^106–126) and fragments of the Alzheimer's protein precursor, APP, have been shown to be cytotoxicin vitro.We have used synchronous, clonal cell models originally developed to study the toxicity of the Alzheimer's disease amyloid peptide, Aβ25–35, to investigate the actions of PrP peptides. We found that the cytotoxicity of the PrP^106–126depends on its state of aggregation and the cellular expression of PrP^C, and is independent of a loss of MTT reduction activity in the absence of cell death associated with the cellular effects of Aβ25–35. These factors may play a role in the lesion specificity of different pathological phenotypes of prion-protein related diseases.