Genomic integration of Wnt/b-catenin and BMP/Smad1 coordinates the transcriptional program of foregut and hindgut progenitors [ChIP-seq]

Digestive system development is orchestrated by combinatorial signaling interactions between endoderm and mesoderm, but how they are integrated in the genome is poorly understood. Here we identified the Xenopus foregut and hindgut progenitor transcriptomes, which are largely conserved with mammals. Using RNA-seq and ChIP-seq we show that BMP/Smad1 regulates dorsal-ventral gene expression in both the endoderm and mesoderm, whereas Wnt/b-catenin acts as a genome-wide toggle between foregut and hindgut programs. In addition to b-catenin-Tcf promoting hindgut gene transcription, we unexpectedly observed Wnt-repressed foregut genes associated with b-catenin-binding to DNA lacking Tcf motifs, suggesting a novel direct repression. We define how BMP and Wnt signaling are integrated in the genome with Smad1 and β-catenin co-occupying DNA elements associated with hundreds of key regulatory genes. These results extend our understanding of GI organogenesis and how Wnt and BMP may coordinate genomic responses in other contexts. ChIP of whole embryos, foregut and hindgut explants for 3 different antibodies (b-catenin, Smad1 and p300).