Apolipoprotein E inhibits liposome fusion induced by the alzheimer's beta-amyloid peptide

C-terminal fragments of the Alzheimer's beta-amyloid peptide (amino acids 29-40 and 29-42) are able to induce the fusion of lipid vesicles, suggesting that a direct interaction of the beta-amyloid peptide with cell membranes might account for part of the cytotoxicity of the peptide. As apolipoprotein E polymorphism has been shown to influence the pathology of alzheimer's disease, we examined the interaction between the apoE isoforms and the amyloid peptide. Our data show that only apo E2 and E3 are inhibitors of the amyloid peptide fusogenic and aggregational properties, Whereas apo E4 has no effect. Stable complexes between apo E2 and E3 and the amyloid peptide could be detected by polyacrylamide gel electrophoresis. The C-terminal domain of the amyloid peptide seems therefore critical for the amyloid- apo E interaction. The apo E2 and E3 isoforms, might play a protective role against the formation of amyloid aggregates and/or against their interaction with cellular membranes, whereas apo E4 has no effect on these properties.