Figure 6

SET7/9-mediated YY1 methylation is involved in YY1-regulated cell proliferation.

(A) HeLa cells were transfected with control siRNA or siRNA specifically targeting YY1 or SET7/9, followed by flow cytometry analysis. Percentage of cells in each cell cycle phase, G0-G1, S and G2-M, was shown as indicated (±s.e.m.). The change of percentage of cells in G0-G1 and S phases between siCTL and siYY1 were both significant (P < 0.001). Experiments were repeated three times and representative data was shown. (B) HeLa cells were transfected with control siRNA or siRNA specifically targeting YY1 or SET7/9, followed by MTS assay to measure cell proliferation rate for two consecutive days. The change of absorbance between siCTL and siYY1 in both day 2 and 3 were significant (P < 0.01 and P < 0.001, respectively). Experiments were repeated three times and representative data was shown. (C) HeLa cells stably expressing control vector, Flag-tagged YY1(wt), YY1(K173R) or YY1(K411R) were seeded at the same density and their proliferation rate was monitored for three consecutive days by MTS assay. Significant test was performed for the change of absorbance between different conditions. In day 2: CTL vs YY1(wt) (P < 0.001), CTL vs YY1(K411R) (P < 0.001); In day 3: CTL vs YY1(wt) (P < 0.001), CTL vs YY1(K411R) (P < 0.01); In day 4: CTL vs YY1(wt) (P < 0.001), CTL vs YY1(K173R) (P < 0.01), CTL vs YY1(K411R) (P < 0.01). Experiments were repeated three times and representative data was shown. (D) The levels of stably expressed Flag-tagged YY1(wt), YY1(K173R) and YY1(K411R) as described in (C) was examined through immunoblotting using anti-YY1 antibody. Endo-YY1: endogenous YY1.