PRC2 suppresses CTNNA1 expression through H3K27 trimethylation. (A) HL-60 cells were treated with 0.6μM TSA for 0 and 12 hours. ChIP analyses were performed with the indicated antibodies. (B) Western blot analyses of EZH2, SUZ12, and α-catenin proteins in HL-60 cells treated with 0.4μM TSA for the indicated times. (C-D) HL-60 cells were infected with retroviral constructs generating SUZ12- and EZH2-specific shRNA. Knockdown of SUZ12 (C) and EZH2 (D), as well as levels of CTNNA1 expression, were determined by both real-time quantitative RT-PCR and Western blot analysis. (E) HL-60 cells were infected with retroviral SUZ12 shRNA, and ChIP analyses were performed with the indicated antibodies at the UP1, P1E1, and I1E2 sites, or at the promoter of the GAPDH gene. Knockdown of SUZ12 resulted in a massive reduction of the repressive H3K27me3, with concomitant increase of the activating H3K4me3 marked specifically at the P1E1 site.