87 - Induction of Beta amyloid Radical fFrmation through Immuno-spin trapping of Copper nano particles: Implication of Protein Radicals in Alzheimer's Disease

Abstract

Alzheimer’s disease (AD) is a debilitating progressive neurodegenerative disease that usually starts slowly and worsens over time. Though AD etiology is believed to be multifactorial, there is considerable evidence showing the role of copper exposure in beta-amyloid (βA) aggregation and AD pathogenesis. Owing to the fact that βA aggregation takes place in the synaptic cleft where copper is found in high concentrations, copper exposure especially in the form of nano particles can be more detrimental. Though copper-induced oligomeric forms of βA accumulate and significantly damage the brain cells, inducing cognitive dysfunctions, the mechanism that initiates and promotes βA oligomerization remains unknown. We hypothesized protein radical formation as an initiating mechanism for βA oligomerization. Therefore, we used the highly sensitive immuno-spin trapping technique to investigate protein radical formation as a possible mechanism of βA oligomerization. Here, we have investigated copper nano particles induced βA radical formation and results clearly showed that both variants of nano particles (25 and 70 nm sizes) significantly produced βA radical in presence of hydrogen peroxide. To further validate copper nano particle-induced protein radical formation in biological context, we exposed IMR-32 hippocampal neuroblastoma cells expressing βA to both variants of copper nano particles and analyzed protein radical formation using confocal microscopy. Confocal microscopy results clearly showed protein radical formation in IMR-32 cells exposed to either variant of copper nano-particles in presence of hydrogen peroxide. Taken together, these results clearly suggest that both variants of copper nano particles induce βA radical formation which can lead to βA oligomerization, and therefore contributes to AD pathogenesis.