Screening the morphological landscape of amyloid aggregates with atomic force microscopy and infrared spectroscopy.

Amyloids exhibit structural diversity based on their aggregation states (oligomers, seeds, end state fibrils, etc.) and can form distinct structural polymorphs. Crucially, this diversity correlates with different pathological outcomes and rates of disease progression. This project aims at deepening our understanding of the inconsistencies between in vivo and in vitro amyloid formation and how amyloid polymorphism correlates with variable disease phenotypes. Cryo-electron microscopy has been pivotal in determining the structures of amyloid aggregates at atomic resolution but we need a screening method that can facilitate reliable and efficient highthroughput analysis of amyloid polymorphs without extracting the deposits from the tissue. I will focus on the structural polymorphism of two model amyloidforming proteins (Abeta and tau) using samples of increasing complexity. Using a state-of-the-art approach (atomic force microscopy-infrared spectroscopy), I will study the impact of reaction conditions during aggregate formation on the structural diversity of amyloid aggregates produced in vitro. These results will be crosscorrelated with in situ and ex vivo aggregates obtained from reporter cell lines and animal models. Following an unsupervised computational approach for clustering, I will explore the impact of experimental conditions during fibril formation and extraction on fibril structure, seeding capacity, and the limitations of structural compatibility.