Nrf2 mediates the expression of BAG3 and autophagy cargo adaptor proteins and tau clearance in an age-dependent manner

During aging, decreased efficiency of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) activation and autophagic processes in the brain may be a contributing factor in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease. Therefore, we analyzed the expression of Bcl-2-associated athanogene 3, a cochaperone that mediates autophagy, and the autophagy adaptors NBR1, NDP52, and sequestosome 1/p62 in the brains of 4-, 8-, and 12-month-old wild-type and Nrf2 knockout (−/−) mice. We also analyzed the levels of total tau and phospho-tau species. There were minimal differences in the expression of autophagy-related genes or tau species in 4-month-old animals; however, by 12 months, all of these autophagy-associated genes were expressed at significantly lower levels in the Nrf2 (−/−) mice. The decreases in the autophagy-associated genes were accompanied by significantly elevated levels of phospho-tau species in the 12-month-old Nrf2 (−/−) brains. These findings indicate that Nrf2 regulation of autophagy-related genes likely plays a greater role in mediating the clearance of tau as an organism ages.