Amyloid-binding compounds maintain protein homeostasis during ageing and extend lifespan

Abstract

The amyloid-binding histological dye thioflavin T (ThT) is known to slow protein aggregation in vitro. Experiments in Caenorhabditis elegans, commonly used as a model system for the study of ageing, now show that ThT also extends lifespan and slows ageing in the nematode. It inhibits the pathology caused by worm-specific toxic proteins and human β-amyloid expression. These beneficial effects depend on heat shock factor 1 (HSF-1), transcription factor SKN-1, molecular chaperones, autophagy and proteosomal functions. This work shows that the ageing rate in worms can be modulated by pharmacological maintenance of protein homeostasis. Genetic studies indicate that protein homeostasis is a major contributor to metazoan longevity1. Collapse of protein homeostasis results in protein misfolding cascades and the accumulation of insoluble protein fibrils and aggregates, such as amyloids2. A group of small molecules, traditionally used in histopathology to stain amyloid in tissues, bind protein fibrils and slow aggregation in vitro and in cell culture3,4. We proposed that treating animals with such compounds would promote protein homeostasis in vivo and increase longevity. Here we show that exposure of adult Caenorhabditis elegans to the amyloid-binding dye Thioflavin T (ThT) resulted in a profoundly extended lifespan and slowed ageing. ThT also suppressed pathological features of mutant metastable proteins and human β-amyloid-associated toxicity. These beneficial effects of ThT depend on the protein homeostasis network regulator heat shock factor 1 (HSF-1), the stress resistance and longevity transcription factor SKN-1, molecular chaperones, autophagy and proteosomal functions. Our results demonstrate that pharmacological maintenance of the protein homeostatic network has a profound impact on ageing rates, prompting the development of novel therapeutic interventions against ageing and age-related diseases.