Figure 7.

MARK4^ΔG316E317D promotes misfolding of tau. A, MARK4^wt and MARK4^ΔG316E317D promoted accumulation of tau oligomers and dimers at similar levels. Western blotting was performed on fly head lysates prepared under nonreducing conditions with oligomer-specific antibody T22 (oligomer) and pan-tau antibody Tau5 (dimer). Representative blots and quantification are shown. Actin was used as a loading control. Means ± S.D. (error bars); n = 3. n.s. (not significant), p > 0.05; *p < 0.05, **p < 0.01 (one-way ANOVA and Tukey's post-hoc test). B and C, tau in extracts from heads expressing tau alone (tau), coexpressing tau and MARK4^wt (tau+MARK4^wt), or coexpressing tau and MARK4^ΔG316E317D (tau+MARK4^ΔG316E317D) were detected by Western blotting with pan-tau antibody T46. Head homogenates were extracted first with RIPA buffer containing NP-40 (NP-40), next with 2% SDS (SDS), and finally with 70% formic acid (FA). B, representative Western blots are shown (shorter exposure (upper panel) and longer exposure (lower panel)). C, Western blotting was performed on fly heads extracted with RIPA buffer containing NP-40 (NP-40) and then with 2% SDS (SDS). Representative blots (left) and quantification (right) are shown.