Fig. 6

TFCP2 binds to the core TF-binding region of CPEB1 when it is hypermethylated. a Silver staining of the nucleoproteins identified in DNA pull-down assay under various conditions. p-WT, the non-methylated CPEB1 promoter; p-Me, the hypermethylated CPEB1 promoter; control, magnetic beads without probes; Input, total nucleoproteins extracted from HCT116 cells; M, protein molecular mass marker. b WB detecting immunoreactive CEBPB in the nucleoprotein fraction after DNA pull-down with the anti-CEBPB antibody. The molecular mass of CEBPB is approximately 35 kDa. c EMSA revealed that CEBPB protein was unable to bind to its target sequence in the hypermethylated TF-binding region of CPEB1; 50 × cold probe WT, 50-fold concentration of the unlabelled wild-type CPEB1 promoter which was served as the competitor probe; Bio-Probe WT, a biotin-labelled wild-type probe of CPEB1 upstream region; Bio-Probe Mut, a biotin-labelled mutant probe of CPEB1 upstream region; Nucleoprotein, nucleoprotein extracted from HCT116 cells; Me-Bio Probe WT, a biotin-labelled hypermethylated probe of CPEB1 upstream region. d TFCP2 may be a candidate methylation reader at the upstream region of CPEB1; Methylation, the hypermethylated CPEB1 upstream region probe; Wild-type, the wild-type CPEB1 upstream region probe; Control, a probe with a scrambled sequence of CPEB1 upstream region; TF, the TFs capable of binding to the CPEB1 upstream as determined by ChIP-Seq. e Competitive EMSA to confirm TFCP2 as a methylation reader for CPEB1. Bio-probe, a biotin-labelled wild-type CPEB1 upstream region probe; Me-Bio Probe, a biotin-labelled hypermethylated CPEB1 upstream region probe; 50 × Cold Probe, 50-fold concentration of the unlabelled wild-type CPEB1 upstream region probe that served as a competitor of the Bio-probe; 50 × Cold Me-Probe, 50-fold concentration the unlabelled hypermethylated CPEB1 upstream region probe that served as a competitor of the Me-Bio Probe