Effects of Thioflavin T and GSK-3 Inhibition on Lifespan and Motility in a Caenorhabditis elegans Model of Tauopathy

The nematode Caenorhabditis elegans (C. elegans) is a powerful model organism to study lifespan and aging, protein aggregation, and neurodegeneration, as well as to carry out drug screenings. The C. elegans strain aex-3/T337 expresses human pathogenic V337M mutant tau under a pan-neuronal promoter and presents uncoordinated locomotion, accumulation of phosphorylated insoluble tau, and shortened lifespan. Herein we have used this strain to assay two compounds that could affect tau aggregation and/or phosphorylation, and looked for phenotypic changes in their lifespan and motility. The first compound is Thioflavin T (ThT), a member of the tetracycline family with protein antiaggregant properties, yet to be tested in a tauopathy model. The second is a novel small molecule, NP103, a highly selective inhibitor of glycogen synthase kinase-3 (GSK-3), the main kinase contributing to pathogenic tau hyperphosphorylation. Importantly, we find that ThT extends lifespan of aex-3/T337 worms as it does with control N2 animals, showing both strains similar locomotion features under this treatment. By contrast, NP103 improves the paralysis phenotype of aex-3/T337 mutants but not their lifespan. Our results show that both treatments present beneficial effects for this model of tauopathy and encourage pursuing further investigations on their therapeutic potential for AD and other tauopathies.