Figure 2.

PLK4 Inhibition Reduces MRTF-A Protein and SRF Activity

(A) Effect of PLK4 silencing on MRTF-A. Cells were transfected with scrambled or PLK4-specific siRNA for 48 h in the complete medium, starved overnight, and then stimulated with solvent or AA for 24 h before harvest for Western blotting. (B) Effect of PLK4 inhibition on MRTF-A. Cells were pretreated with 1 μmol/l CenB (or vehicle) and then stimulated with solvent or AA for 48 h before harvest for Western blotting. Mean ± SEM, n = 3 experiments, 1-way ANOVA/Bonferroni test: #p < 0.05; ##p < 0.01; ###p < 0.001. ∗p < 0.05. ∗∗p < 0.01; ∗∗∗p < 0.001 compared with the control of scrambled siRNA or vehicle without AA stimulation (the first bar in each plot). (C) Luciferase reporter assay of SRF transcriptional activity. Cells were transfected with the empty vector control or the SRF-luciferase vector, followed by luminescence reading. The condition with 5 μmol/l tubastatin-A, a histone deacetylase 6 inhibitor and a novel SRF stimulator (13), served as a positive control. Mean ± SEM, n ≥3 experiments, Student t-test: ##p < 0.01; ###p < 0.001 (between 2 gray bars). MRTF-A = myocardin-related transcription factor A; SRF = serum response factor; other abbreviations as in Figure 1.