In situgeneration of Aβ42oligomers via secondary nucleation triggers neurite degeneration and synaptic dysfunction in human iPSC-derived glutamatergic neurons

Abstract

AbstractThe aggregation of Aβ42 into misfolded oligomers is a central event in the pathogenesis of Alzheimer’s disease. In this study, we aimed to develop a robust experimental system that recapitulates Aβ42 oligomerization in living cells to gain insight into their neurotoxicity and to provide a platform to characterize the effects of inhibitors of this process. Our strategy is based on thein situgeneration of Aβ42 oligomers via secondary nucleation by repeatedly treating the cells with Aβ42 monomers in the presence of pre-formed Aβ42 fibrils. This approach enables an accurate control over the levels of on-pathway soluble Aβ42 oligomers and cell-associated aggregates, as well as the study of their neurotoxic effects. By implementing this approach in human glutamatergic neurons derived from induced pluripotent stem cells (iPSCs), we were able to replicate key aspects of Alzheimer’s disease, including neurite degeneration and synaptic dysfunction. Using BRICHOS, a molecular chaperone that specifically inhibits secondary nucleation, we confirmed that aggregation in this system occurs through secondary nucleation, and that quantitative parameters for comparing potential Aβ42 aggregation inhibitors can be obtained. Overall, our results demonstrate that byin situgeneration of on-pathway Aβ42 oligomers, one can obtain translational cellular models of AD to bridge the gap between basic research and clinical applications.