Kinetic Modulation of Amyloid‐β (1‐42) Fibrillation and Alleviated Cytotoxicity with Rationally Designed Point Mutants

Abstract

Background Most Alzheimer’s disease (AD) treatments focus on symptomatic relief by boosting the availability of neurotransmitters in the brain. Aside from symptomatic therapies, the amyloid‐β (Aβ) targeting approach has recently been established to reduce or postpone the production of Aβ plaques.1 Therefore, understanding the pathogenesis of AD requires regulation of Aβ fibrillation. Method We used the CamSol method and molecular dynamics simulations to find a group of residues that were significantly associated with Aβ fibrillation. To investigate the suppressed amyloid aggregation and reduced cytotoxicity of the designed mutants, we performed multiple in vitro experiments such as thioflavin T assay, circular dichroism spectroscopy measurement, transmission electron microscopy image analysis, liquid chromatography‐mass spectrometry based quantification, and cell viability test. We also characterized structural dynamics of the designed mutants using a multidisciplinary biophysical approach with small‐angle X‐ray scattering, ion mobility‐mass spectrometry, additional in silico experiments, and mass spectrometry. Result We rationally designed mutant constructs to suppress the fibrillation process using comprehensive molecular dynamics simulations and the atomic resolution structure of fibrils. Then, we used a multidisciplinary biophysical technique to investigate the physicochemical characteristics and unveil the structural basis associated with reduced self‐assembly. Lastly, cell‐based tests were performed to evaluate the alleviated cytotoxicity of designed mutant candidates. Conclusion More generally, our method for modulating the self‐assembly property of the pathologically disordered proteins offers a novel viewpoint to treating neurodegenerative diseases and other protein folding‐related issues. Reference: 1. Sevigny, J., et al. “The antibody aducanumab reduces A beta plaques in Alzheimer’s disease.” Nature 2016, 537(7618), 50‐56.