The Effect of Ethanol on Disassembly of Amyloid-β1-42 Pentamer Revealed by Atomic Force Microscopy and Gel Electrophoresis

Abstract

The most common type of dementia, Alzheimer’s disease, is associated with senile plaques formed by the filamentous aggregation of hydrophobic amyloid-β (Aβ) in the brains of patients. Small oligomeric assemblies also occur and drugs and chemical compounds that can interact with such assemblies have attracted much attention. However, these compounds need to be solubilized in appropriate solvents, such as ethanol, which may also destabilize their protein structures. As the impact of ethanol on oligomeric Aβ assembly is unknown, we investigated the effect of various concentrations of ethanol (0 to 7.2 M) on Aβ pentameric assemblies (Aβp) by combining blue native-PAGE (BN-PAGE) and ambient air atomic force microscopy (AFM). This approach was proven to be very convenient and reliable for the quantitative analysis of Aβ assembly. The Gaussian analysis of the height histogram obtained from the AFM images was correlated with band intensity on BN-PAGE for the quantitative estimation of Aβp. Our observations indicated up to 1.4 M (8.3%) of added ethanol can be used as a solvent/vehicle without quantitatively affecting Aβ pentamer stability. Higher concentration induced significant destabilization of Aβp and eventually resulted in the complete disassembly of Aβp.

Nanomechanical Profiling of Aβ42 Oligomer-Induced Biological Changes in Single Hippocampus Neurons

“…The statistics show that the apparent height of the Aβ42 oligomers ranges from 1.7 to 4.7 nm and centers around 2.29 ± 0.09 nm by applying the Gaussian fitting to the data (Figure C). These structural parameters are consistent with the previously described pentamer structure of the Aβ42 oligomer …”

“…These structural parameters are consistent with the previously described pentamer structure of the Aβ42 oligomer. 38 Next, we evaluated the effects of Aβ42 oligomers on the viability of neurons using a CCK-8 assay. From Figure 2D, it can be found that the survival rate of neurons dropped with increasing concentration of Aβ42 oligomers, which is consistent with previous studies on neuronal cells.…”