FIGURE 4.

Psen1/2 dKO-dependent hyperactivation of GSK3 contributes to neurotrypsin up-regulation and enhanced activity. A, Western blot analysis of P-S9-GSK3β and total GSK3β in WT, Psen1/2 dKO, and Psen1/2 dKO cells rescued with hPSEN1/2 or catalytically inactive D257A hPSEN1 and wild-type hPSEN2. Samples were run in the same gel but were cut and pasted to adjust the order of lanes displayed in this panel. B, Western blot analysis of β-catenin and actin levels in cellular lysates and agrin-90 and agrin-22 in conditioned medium from Psen1/2 dKO cells treated for 24 h with 50 mm LiCl or vehicle (left panel). RT-qPCR analysis of Tbp-normalized neurotrypsin (middle panel) and Agrn (right panel) mRNA expression from the same samples is shown. C, as in B but treated for 24 h with 0.1 μm factor XV or vehicle. D, as in B but treated for 24 h with purified Wnt3a and DMSO (vehicle) or Wnt3a and 1 μm IWR (IWR). All experiments shown in this figure were triplicates (n = 3). Representative Westerns are shown. Mean ± S.E. is shown. p values relative to control/wild type are shown when significant (Student's t test): **, p ≤ 0.01; ***, p ≤ 0.001. n.s., not significant. Error bars represent S.E.