Cell surface binding and internalization of a modulated by degree of aggregation

Abstract

The amyloid peptides, A40 and A42, are generated through endoproteolytic cleavage of the amyloid precursor protein. Here we have developed a model to investigate the interaction of living cells with various forms of aggregated A40/42. After incubation at endosomal pH 6, we observed a variety of A conformations after 3 (Aß3), 24 (Aß2ß4), and 90 hours (Aß9ß0). Both A42ß2ß4 and A40ß2ß4 were observed to rapidly bind and internalize into differentiated PC12 cells, leading to accumulation in the lysosome. In contrast, A40/42ß9ß0 were both found to only weakly associate with cells, but were observed as the most aggregated using dynamic light scattering and thioflavin-T. Internalization of A40/42ß2ß4 was inhibited with treatment of monodansylcadaverine, an endocytosis inhibitor. These studies indicate that the ability of A40/42 to bind and internalize into living cells increases with degree of aggregation until it reaches a maximum beyond which its ability to interact with cells diminishes drastically. Copyright 2011 David A. Bateman and Avijit Chakrabartty.