The cell-selective neurotoxicity of the Alzheimer's Abeta peptide is determined by surface phosphatidylserine and cytosolic ATP levels. Membrane binding is required for Abeta toxicity.
Measurement of Abeta toxicity of cells in culture exposes a subpopulation of cells with resistance to Abeta, even at high concentrations and after long periods of treatment. The cell-selective toxicity of Abeta resembles the selective damage observed in cells of specific regions of the Alzheimer's disease (AD) brain and suggests that there must be particular characteristics or stages of these cells that make them exceptionally sensitive or resistant to the effect of Abeta. Using flow cytometry and cell sorting, we efficiently separated and analyzed the Abeta-sensitive and the Abeta-resistant subpopulations within a variety of neuronal cell lines (PC12, GT1-7) and primary cultured neurons (hippocampal, cortex). We found that this distinctive sensitivity to Abeta was essentially associated with cell membrane Abeta binding. This selective Abeta binding was correlated to distinctive cell characteristics, such as cell membrane exposure of the apoptotic signal molecule phosphatidyl serine, larger cell size, the G1 cell cycle stage, and a lower than normal cytosolic ATP level. The response to Abeta by the cells with high Abeta binding affinity was characterized by a larger calcium response and increased mortality, lactate dehydrogenase release, caspase activation, and DNA fragmentation. The distinctive sensitivity or resistance to Abeta of the different subpopulations was maintained even after multiple cell divisions. We believe that these distinctive cell characteristics are the determining factors for the selective attack of Abeta on cells in culture and in the AD brain.
Simakova
Olga
O
Department of Anatomy, Physiology, and Genetics and Institute for Molecular Medicine, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.
Arispe
Nelson J
NJ
D000255:Adenosine Triphosphate / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000737:chemistry / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001667:Binding, Competitive; D002118:Calcium / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D048429:Cell Size; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism*; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D016501:Neurites / Q000187:drug effects; D009474:Neurons / Q000145:classification / Q000187:drug effects* / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000633:toxicity*; D010718:Phosphatidylserines / Q000378:metabolism*; D051381:Rats; D013997:Time Factors
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D010718:Phosphatidylserines; C075222:amyloid beta-protein (1-42); D000255:Adenosine Triphosphate; D020169:Caspases; D016650:Fluorescein-5-isothiocyanate; D002118:Calcium