Figure 3.

YY1 regulates c-Myc transcriptional activity via the c-Myc/Max/Mad network. A, subcellular colocalization of endogenous YY1 and c-Myc detected by immunofluorescence in 5-8F and HNE2 cell lines. Images were obtained via confocal microscopy. B and C, co-IP assays and Western blotting confirmed the interaction between YY1 and c-Myc in HEK293 cells. D and E, dual-luciferase reporter assays confirmed the transcriptional activity of c-Myc toward the consensus E-box sequence (D) and the effect of YY1 overexpression on c-Myc activity (E) in HNE2 and 5-8F cells. Data are normalized to Renilla activity (pRL-TK). F, effect of YY1 on c-Myc binding to Max or Mad was investigated by co-IP and Western blotting, and the amount of c-Myc binding to Max or Mad reflected the transcriptional activity intensity of c-Myc. Error bars represent the mean ± S.D. ***, p < 0.001. All experiments were performed in triplicate. IB, immunoblot.