Cytotoxicity of Prion Protein Peptide (PrP 106–126) 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 cytotoxic in 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.