Figure 5.

DKK1 knock-down attenuates cell death, GSK3β activation, and tau hyperphosphorylation in βAP-treated neurons. a, Real-time PCR analysis of DKK1 mRNA in neurons exposed to 25 μm βAP(25-35) for 16 hr in the presence or absence of DKK1 antisenses (DKK-As) or senses (DKK-Sn). Values are means ± SEM of normalized DKK1 from four determinations. ^*p < 0.05 versus controls (CTRL), or ^*# βAP alone (one-way ANOVA followed by Fisher's LSD test). The effect of DKK-As on neuronal survival (b), GSK3β activation, and tau hyperphosphorylation (c) in cultures exposed to 25 μm βAP(25-35) for 20 hr is shown. In b, values represent the means ± SEM of six determinations. ^*p < 0.05 versus controls (CTRL), or ^*# βAP alone (one-way ANOVA followed by Fisher's LSD test). In c, the immunoblot of PHF-1 was obtained from neuronal cultures treated with βAP in the presence of 20 μm z-DEVD. The β-actin band is shown for comparison. The immunoblot is representative of three independent experiments with similar results. The immunoblot of phospho(ser9)-GSK3β was obtained under the same conditions and repeated twice with similar results.