Tolfenamic acid reduces tau and CDK5 levels: implications for dementia and tauopathies.

Tau and its aggregates are linked to the pathology of Alzheimer's disease (AD) and other tauopathies and, therefore, are explored as therapeutic targets for such disorders. Tau belongs to a family of microtubule-associated proteins that promote microtubule assembly. When hyperphosphorylated, tau becomes prone to forming aggregates. Increased brain levels of hyperphosphorylated tau correlate with dementia. Specificity protein 1 (Sp1), a transcription factor elevated in AD, is responsible for the transcription of AD-related proteins including the amyloid precursor protein, tau, and its cyclin-dependent kinase-5 (CDK5) activators. Tolfenamic acid promotes the degradation of Sp1, our previous studies demonstrated its ability to down-regulate transcriptional targets of Sp1 like amyloid precursor protein and reduce amyloid beta (Aβ), the main component of AD plaques. In this study, we administered tolfenamic acid daily to hemizygous R1.40 transgenic mice for 34 days, and examined tau and CDK5 gene and protein expression within the brain. Our results demonstrate that tolfenamic acid lowers tau mRNA and protein, as well as the levels of its phosphorylated form and CDK5. Thus, we present a drug candidate that inhibits the transcription of multiple major intermediates in AD pathology, thereby helping uncover a new mechanism-based approach for targeting AD. A new approach for targeting Alzheimer's disease through a transcriptional based mechanism is presented. Tolfenamic acid lowers the levels of tau, which forms pathological aggregates in Alzheimer's disease and other tauopathies, by promoting the degradation of the transcription factor specificity protein 1 which regulates tau transcription.