Annexin 5 and apolipoprotein E2 protect against Alzheimer's amyloid-beta-peptide cytotoxicity by competitive inhibition at a common phosphatidylserine interaction site.
Amyloid-beta-protein (betaA/4, AbetaP) accumulates in the brains of patients with Alzheimer's disease (AD), regardless of genetic etiology, and is thought to be the toxic principle responsible for neuronal cell death. The varepsilon4 allele of apoE has been linked closely to earlier onset of AD and increased deposition of the amyloid peptide, regardless of the clinical status of AD, while the apoE varepsilon2 allele is generally protective. We have previously hypothesized that the cell target for amyloid peptide might be the apoptotic signal molecule phosphatidylserine (PS). We report here that annexin 5, a specific ligand for PS, not only blocks amyloid peptide AbetaP[1-40] cytotoxicity, but competitively inhibits AbetaP[1-40]-dependent aggregation of PS liposomes. In addition, we find that apoE2, but not apoE4, can not only perform the same protective effect on cells exposed to AbetaP[1-40], but can also competitively inhibit PS liposome aggregation and fusion by the amyloid peptide. Altogether, the in vivo and in vitro results reported here provide fundamental insight to the process by which amyloid targets specific neurons for destruction, and suggest that PS may be a surface "receptor" site for AbetaP binding. These results also provide a biochemical mechanism by which the apoE varepsilon2 allele, but not apoE varepsilon4, can be protective towards the incidence and progression of Alzheimer's disease.
Lee
George
G
Laboratory of Cell Biology and Biochemistry, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
Pollard
Harvey B
HB
Arispe
Nelson
N
D000544:Alzheimer Disease / Q000517:prevention & control*; D016229:Amyloid beta-Peptides / Q000187:drug effects / Q000633:toxicity*; D000818:Animals; D017302:Annexins / Q000378:metabolism* / Q000494:pharmacology; D053329:Apolipoprotein E2; D001057:Apolipoproteins E / Q000378:metabolism* / Q000494:pharmacology; D001665:Binding Sites; D002118:Calcium / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D006801:Humans; D007700:Kinetics; D008081:Liposomes / Q000378:metabolism; D008561:Membrane Fusion / Q000187:drug effects; D008954:Models, Biological; D016716:PC12 Cells; D010446:Peptide Fragments / Q000187:drug effects / Q000633:toxicity*; D010718:Phosphatidylserines / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D020033:Protein Isoforms / Q000378:metabolism / Q000494:pharmacology; D051381:Rats
D016229:Amyloid beta-Peptides; D017302:Annexins; D053329:Apolipoprotein E2; D001057:Apolipoproteins E; D008081:Liposomes; D010446:Peptide Fragments; D010718:Phosphatidylserines; D020033:Protein Isoforms; C078592:amyloid beta-protein (1-40); D002118:Calcium