Pharmacological Interrogation of the C. elegans Pharyngeal Cuticle Reveals Small Molecule Amyloid Disruptors

Abstract

Amyloids are associated with over 50 human diseases and have inspired significant effort to identify small molecule remedies. Here, we present a novel in vivo platform that efficiently yields small molecule disruptors of amyloid formation. We previously identified small molecules that kill the nematode C. elegans by forming membrane-piercing crystals in the pharynx cuticle, which is rich in amyloid-like material. We show here that many of these molecules are known amyloid-binders whose crystal-formation in the pharynx can be blocked by amyloid-binding dyes. Furthermore, we found that amyloid fibrils can seed small molecule crystal formation in vitro. These observations suggest that small molecule crystals are seeded by the cuticles amyloid-like material. We asked whether this phenomenon could be exploited to identify additional molecules that interfere with the ability of amyloids to seed higher-order structures. We screened 2560 compounds and identified 85 crystal suppressors, which we found to be 10-fold enriched in known amyloid disruptors relative to a random set. Of the uncharacterized suppressors, we found 25% to inhibit Ab42 fibril nucleation and/or extension in vitro, which is a hit rate that far exceeds other screening methodologies. Hence, screens for suppressors of crystal formation can efficiently reveal small molecules with amyloid-disrupting potential.