Abstract
BACKGROUND: Aggregation of the amyloid peptides, Abeta40 and Abeta42, is known to be involved in the pathology of Alzheimer's disease (AD). Here we investigate the relationship between peptide aggregation and cell surface binding of three forms of Abeta (Abeta40, Abeta42, and an Abeta mutant). RESULTS: Using confocal microscopy and flow cytometry with fluorescently labelled Abeta, we demonstrate a correlation between the aggregation propensity of the Alzheimer amyloid peptides and their neuronal cell surface association. We find that the highly aggregation prone Abeta42 associates with the surface of neuronal cells within one hour, while the less aggregation prone Abeta40 associates over 24 hours. We show that a double mutation in Abeta42 that reduces its aggregation propensity also reduces its association with the cell surface. Furthermore, we find that a cell line that is resistant to Abeta cytotoxicity, the non-neuronal human lymphoma cell line U937, does not bind either Abeta40 or Abeta42. CONCLUSION: Taken together, our findings reveal that amyloid peptide aggregation propensity is an essential determinant of neuronal cell surface association. We anticipate that our approach, involving Abeta imaging in live cells, will be highly useful for evaluating the efficacy of therapeutic drugs that prevent toxic Abeta association with neuronal cells.