Figure 5.
Combined treatment with lithium and VPA potentiates inhibition of GSK-3 activity. CGCs at 6 DIV were treated with 3 mm LiCl, 0.8 mm VPA, or a combination of the two for 24 h. Cells were harvested for Western blotting of levels of p-TauSer400, p-TauThr205, total Tau, and GAPDH (as a loading control). Typical blots are shown in A, and quantified results (means ± SEM from three independent experiments) are in B. *p < 0.05, **p < 0.01 between the indicated groups. Note that p-TauSer400, p-TauThr205, and total Tau appeared as doublets in the Western blots, which likely reflects differential degrees of glycosylation (Liu et al., 2002). C, Cortical neurons at 6 DIV were treated with 3 mm LiCl, 0.8 mm VPA, or their combination for 24 h. Cells were harvested for Western blotting analysis of p-GSK-3αSer21, p-GSK-3βSer9, and p-TauSer400. D, Cell lysates prepared from CGCs at 7 DIV were immunoprecipitated with anti-GSK-3β antibody. The immunocomplex was then assayed for GSK-3β enzymatic activity in the absence or presence of LiCl (3 mm), VPA (0.8 mm), or a combination of both. The data are means ± SEM of percentage of control from three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001 between the indicated groups.