A Toxicogenic Interaction between Intracellular Amyloid-β and Apolipoprotein-E.

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Alzheimer's disease (AD) pathogenesis involves amyloid-beta (Aβ) and tau protein aggregation.
• Apolipoprotein E (ApoE) variants are key genetic risk factors for AD, but their precise role, particularly intracellularly, is unclear.

Purpose of the Study:

• To investigate the intracellular interaction between Aβ oligomers and ApoE in the context of AD.
• To determine how ApoE influences Aβ oligomer properties and toxicity.
• To explore the potential of Aβ-ApoE interactions as a target for AD drug discovery.

Main Methods:

• Utilized fluorescence lifetime measurements of fluorescently tagged Aβ oligomers in rat brain cells.
• Employed single-molecule techniques to analyze oligomer conformation and stoichiometry.
• Assessed the impact of an Aβ-ApoE interaction inhibitor on Aβ toxicity.
• Examined neural stem cells derived from Alzheimer's patient iPSCs.

Main Results:

• Cellular ApoE content correlated with specific changes in Aβ oligomer fluorescence lifetime.
• Inhibition of Aβ-ApoE interaction reduced Aβ toxicity in a dose-dependent manner.
• Single-molecule analysis revealed alterations in Aβ oligomer conformation and stoichiometry due to ApoE interaction.
• Similar fluorescence lifetime changes were observed in Alzheimer's patient-derived neural stem cells.

Conclusions:

• Intracellular ApoE interaction modifies Aβ oligomers, affecting their N-terminus, stoichiometry, membrane affinity, and toxicity.
• These ApoE-induced changes in Aβ oligomers can be imaged in live cells.
• The observed phenomena offer a potential basis for a rapid, quantitative cellular assay for Alzheimer's disease drug discovery.