FIG. 1.

Schematic representation of regulatory regions of Wnt target genes. Shown are parts of the murine Axin2, Cdx1, and T/Bra gene loci. Thin lines represent DNA, TBEs are indicated by red bars and numbered, exons are highlighted in green, and CpG islands are in black. Blue arrowheads mark the location of primer pairs used for genomic bisulfite sequencing. White arrowheads indicate primer pairs used for the analyses of chromatin immunoprecipitates. Numbers refer to nucleotide positions relative to the transcriptional start sites (arrows, +1). For each gene, DNA fragments used to drive the expression of a luciferase reporter gene (yellow bar) are displayed and nucleotide coordinates are shown. In each case, reporter gene expression driven by the promoter fragments used recapitulates important aspects of Axin2, Cdx1, and T/Bra embryonic expression patterns in transgenic animals and mutational inactivation of TCF binding elements contained within the promoter regions abrogates transgene expression in cognate T/Bra, Cdx1, and Axin2 expression domains (7, 48, 81).