Redox-active iron mediates amyloid-β toxicity

While amyloid-β toxicity is mediated by oxidative stress and can be attenuated by antioxidants, the actual biochemical mechanism underlying neurotoxicity remains to be established. However, since aggregated amyloid-β can interact with transition metals, such as iron, both in vitro and in vivo, we suspected that bound iron might be the mediator of toxicity such that holo- and apo-amyloid would have differential effects on cellular viability. Here we demonstrate that when amyloid-β is pretreated with the iron chelator deferoxamine, neuronal toxicity is significantly attenuated while conversely, incubation of holo-amyloid-β with excess free iron restores toxicity to original levels. These data, taken together with the known sequelae of amyloid-β, suggest that the toxicity of amyloid-β is mediated, at least in part, via redox-active iron that precipitates lipid peroxidation and cellular oxidative stress.