4-Phenylbutyric acid attenuates amyloid-ß proteotoxicity through activation of HSF-1 in an Alzheimer's disease model of the nematode Caenorhabditiselegans.

Alzheimer's disease (AD) is a neurodegenerative disorder and the most common form of dementia. The pathogenesis is a complex process, in which the proteotoxicity of amyloid-ß (Aß) was identified as a major factor. 4-Phenylbutyric acid (4-PBA) is an aromatic short-chain fatty acid that may attenuate Aß proteotoxicity through its already shown properties as a chemical chaperone or by inhibition of histone deacetylases (HDACs). In the present study, we investigated the molecular effects of 4-PBA on Aß proteotoxicity using the nematode Caenorhabditis elegans as a model. Computer-based analysis of motility was used as a measure of Aß proteotoxicity in the transgenic strain GMC101, expressing human Aß1-42 in body wall muscle cells. Aß aggregation was quantified using the fluorescent probe NIAD-4 to correlate the effects of 4-PBA on motility with the amount of the proteotoxic protein. Furthermore, these approaches were supplemented by gene regulation via RNA interference (RNAi) to identify molecular targets of 4-PBA. 4-PBA improved the motility of GMC101 nematodes and reduced Aß aggregation significantly. Knockdown of hsf-1, encoding an ortholog essential for the cytosolic heat shock response, prevented the increase in motility and decrease in Aß aggregation by 4-PBA incubation. RNAi for hda-1, encoding an ortholog of histone deacetylase 2, also increased motility. Double RNAi for hsf-1 and hda-1 revealed a dominant effect of hsf-1 RNAi. Moreover, 4-PBA failed to further increase motility under hda-1 RNAi. Accordingly, the results suggest that 4-PBA attenuates Aß proteotoxicity in an AD-model of C. elegans through activation of HSF-1 via inhibition of HDA-1.