Figure 12.

Regulation of intestinal specification in C. elegans Raj et al. (2010): (a) Gene circuit controlling intestinal differentiation in wild-type E cells: master differentiation regulator gene elt-2 is redundantly activated by both End-1 and End-3 transcription factors, which are activated by the maternal protein Skn-1 either directly (End-1) or indirectly, via Med-1, Med-2 and End-3. End-3 also co-regulates expression of end-1; (b) In a mutant skn-1 strain, med-1, med-2 are not expressed, therefore the indirect activation of elt-2 and co-regulation of end-1 by end-3 are disabled. (c) Number of transcripts of end-1 and elt-2 vs time (measured in the number of nuclei) in the wild type (left) and skn-1 mutant (right). Misregulation of the intestinal specification circuit results in a highly variable expression of end-1 and a bimodal distribution of elt-2 transcripts.