Screening for modulators of aggregation with a microplate elongation assay

Many protein misfolding or conformational diseases, a number of which are neurodegenerative, are associated with the presence of proteinaceous deposits in the form of amyloid/amyloid-like fibrils/aggregates in tissues. Little is known about the exact mechanisms by which fibrillar aggregates are formed and can impair cellular functions leading to cell death. Small molecules that can modulate aggregate formation and/or structure can be powerful tools for studying the aggregate assembly mechanism and toxicity and may also prove to be therapeutic. We describe here a microplate-based high-throughput screening assay for identification of such molecules. The assay is based on the ability of microplate-coated aggregates to grow by incorporating additional monomers. Compounds that influence the elongation reaction are selected as hits and are tested in dose-response experiments. We also discuss some additional experiments that can be used to characterize the modes of action of these aggregation modulators further.