FIG 9.

Mitogens induce an exchange of transcriptional regulatory complexes at Myc 5′ and 3′ Wnt-responsive elements. (A) Diagram of the Myc locus, with the Myc 5′ and 3′ WREs indicated by white rectangles. Gray rectangles indicate the positions of the amplicons produced in quantitative real-time PCRs in panels B to G. (B) The proliferative region of colonic crypts were isolated from 7-week-old WT mice and were untreated (Ctrl.) or treated with recombinant Wnt3A, EGF, and R-spondin1 (mitogens) for 3 h. ChIP assays were performed by using antibodies directed against RNA polymerase 2 (RNAP), and the precipitated DNA was measured by using quantitative real-time PCR with oligonucleotides that hybridized to the regions indicated. Colonic crypts were isolated from 3 mice, and 12 PCR replicates were prepared for each sample. Errors are standard errors of the means (**, P < 0.01; ***, P < 0.001). (C to G) Same as panel B except that ChIP assays were conducted with antibodies directed against H3K4me3 (C), TCF4 (D), β-catenin (E), TLE2 (F), or CDX2 (G).