Fisetin stimulates autophagic degradation of phosphorylated tau via the activation of TFEB and Nrf2 transcription factors

• Published in: Scientific reports 2016-04, Vol.6 (1), p.24933-24933, Article 24933
• Main Authors: Kim, Sunhyo, Choi, Ki Ju, Cho, Sun-Jung, Yun, Sang-Moon, Jeon, Jae-Pil, Koh, Young Ho, Song, Jihyun, Johnson, Gail V. W., Jo, Chulman
• Format: Article
• Language: English
• Subjects: 13/106; 13/109; 13/95; 14/28; 14/34; 38; 38/1; 38/89; 38/90; 42/35; 631/378/340; 692/699/375; 82; Alzheimer Disease - metabolism; Alzheimer's disease; Animals; Autophagy; Autophagy - drug effects; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors - metabolism; Carrier Proteins - metabolism; Cell Culture Techniques; Cortex; Flavonoids - pharmacology; Flavonols; Humanities and Social Sciences; Intracellular Signaling Peptides and Proteins; Kinases; multidisciplinary; Neurodegenerative diseases; Neurons - metabolism; NF-E2-Related Factor 2 - metabolism; Phagocytosis; Phosphoprotein phosphatase; Phosphoproteins - metabolism; Phosphorylation; Protein phosphatase; Rapamycin; Rats; Ribosomal protein S6 kinase; Ribosomal Protein S6 Kinases, 70-kDa - metabolism; Science; Science (multidisciplinary); Tau protein; tau Proteins - metabolism; TOR protein; Transcription activation; Transcription factors
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep24933

The neuronal accumulation of phosphorylated tau plays a critical role in the pathogenesis of Alzheimer’s disease (AD). Here, we examined the effect of fisetin, a flavonol, on tau levels. Treatment of cortical cells or primary neurons with fisetin resulted in significant decreases in the levels of phosphorylated tau. In addition, fisetin decreased the levels of sarkosyl-insoluble tau in an active GSK-3β-induced tau aggregation model. However, there was no difference in activities of tau kinases and phosphatases such as protein phosphatase 2A, irrespective of fisetin treatment. Fisetin activated autophagy together with the activation of transcription factor EB (TFEB) and Nrf2 transcriptional factors. The activation of autophagy including TFEB is likely due to fisetin-mediated mammalian target of rapamycin complex 1 (mTORC1) inhibition, since the phosphorylation levels of p70S6 kinase and 4E-BP1 were decreased in the presence of fisetin. Indeed, fisetin-induced phosphorylated tau degradation was attenuated by chemical inhibitors of the autophagy-lysosome pathway. Together the results indicate that fisetin reduces levels of phosphorylated tau through the autophagy pathway activated by TFEB and Nrf2. Our result suggests fisetin should be evaluated further as a potential preventive and therapeutic drug candidate for AD.