Oligomer-specific Aβ toxicity in cell models is mediated by selective uptake

Alzheimer's disease (AD) is characterized by the aggregation and subsequent deposition of misfolded beta-amyloid (A beta) peptide. Previous studies show that aggregated A beta is more toxic in oligomeric than in fibrillar form, and that each aggregation form activates specific molecular pathways in the cell. We hypothesize that these differences between oligomers and fibrils are related to their different accessibility to the intracellular space. To this end we used fluorescently labelled A beta(1-42) and demonstrate that A beta(1-42) oligomers readily enter both HeLa and differentiated SK N SH cells whereas fibrillar A beta(1-42) is not internalized. Oligomeric A beta(1-42) is internalized by an endocytic process and is transported to the lysosomes. Inhibition of uptake specifically inhibits oligomer but not fibril toxicity. Our study indicates that selective uptake of oligomers is a determinant of oligomer specific A beta toxicity. (C) 2008 Elsevier B.V. All rights reserved.