Figure 5

A network model for Foxa2-dependent gene regulation in organizer derivatives. (A) An example of binding motif prediction results visualized using the UCSC genome browser; http://genome.ucsc.edu/[105]. Conserved Foxa2 and Brachyury/T binding motifs were found in the 10 kb region upstream of the endoderm-specific Cer1 gene. (B) A hypothetical network model based on existing genetic data (see Discussion for details and references), and binding motif predictions around putative Foxa2 target genes (Additional Files 1, 9, 10, 11, 12). Brachyury/T is active in node, notochord and axial mesendoderm (ND/NC/AME), but not in definitive endoderm (DE). The transcription factors Foxa2, Brachyury/T, Noto, Foxa1, and/or Foxd4 could regulate putative ND/NC/AME target genes; Foxa2, Foxa1, and/or Sox17 could regulate DE target genes. We propose a role for Brachyury/T in repression of DE targets in the ND/NC/AME lineages. Foxa2 likely regulates itself in both ND/NC/AME and DE. (Note: the network diagram was created using BioTapestry; http://www.biotapestry.org/[106]).