The Alzheimer's disease amyloid precursor protein modulates copper-inducedtoxicity and oxidative stress in primary neuronal cultures

The amyloid precursor protein (APP) of Alzheimer's disease can reduce coppe r (II) to copper (I) in a cell-free system potentially leading to increased oxidative stress in neurons. We used neuronal cultures derived from APP kn ock-out (APP(-/-)) and wild-type (WT) mice to examine the role of APP in co pper neurotoxicity. WT cortical, cerebellar, and hippocampal neurons were s ignificantly more susceptible than their respective APP(-/-) neurons to tox icity induced by physiological concentrations of copper but not by zinc or iron. There was no difference in copper toxicity between APLP2(-/-) and WT neurons, demonstrating specificity for APP-associated copper toxicity. Copp er uptake was the same in WT and APP(-/-) neurons, suggesting APP may inter act with copper to induce a localized increase in oxidative stress through copper (I) production. This was supported by significantly higher levels of copper-induced lipid peroxidation in WT neurons. Treatment of neuronal cul tures with a peptide corresponding to the human APP copper-binding domain ( APP142-166) potentiated copper but not iron or zinc toxicity. Incubation of APP142-166 with low-density lipoprotein (LDL) and copper resulted in signi ficantly increased lipid peroxidation compared to copper and LDL alone. Sub stitution of the copper coordinating histidine residues with asparagines (A PP142-166(H147N, H149N, H151N)) abrogated the toxic effects. A peptide corr esponding to the zinc-binding domain (APP181-208) failed to induce copper o r zinc toxicity in neuronal cultures. These data support a role for the APP copper-binding domain in APP-mediated copper (I) generation and toxicity i n primary neurons, a process that has important implications for Alzheimer' s disease and other neurodegenerative disorders.