Figure 2

Resveratrol reduces the MID1 transcript and protein level in neurons. (a) Schematic showing the effect of resveratrol on MID1. Left: MID1 is a ubiquitin ligase that catalyses the ubiquitination of the catalytic subunit of PP2A (PP2Ac) and thereby stimulates proteasomal degradation of microtubule-associated PP2Ac. MID1 binds to and stabilizes its own mRNA. Right: Resveratrol treatment induces the proteasomal degradation of MID1, which stabilizes and activates PP2A at the microtubules. (b) Primary cortical neurons from wild-type mice were treated with 100 µM resveratrol for 20 hours. Cell lysates were analysed on western blots using antibodies detecting MID1 and actin as loading control (n = 3). (c) Primary cortical neurons from wild-type mice were treated with 100 µM resveratrol for 20 hours and expression levels of MID1 and GAPDH were analysed by real-time PCR. Samples were measured in quadruplicates and the relative MID1 mRNA expression normalized to GAPDH is shown. Columns represent mean values +/− SEM, (n = 4, *p < 0.002). (d) Primary cortical neurons from wild-type mice were treated with a peptide mimicking the MID1-α4 binding site (GSK′364A) or DMSO as negative control (mock) for 6 hours. Cell lysates were analysed on western blots using antibodies detecting Tau phosphorylation at S202, total Tau (Tau-5), and actin. Representative western blots and quantifications of several independent experiments are shown. Band intensities of phospho-Tau were normalized to total Tau (Tau-5). For each experiment the respective control sample was set to 100%. n = 11, *p < 0.001.