Fig. 3.

Autoregulatory circuit of Oct-3/4 and Sox2 gene expression in ES cells. Expression of Oct-3/4 and Sox2 are controlled by the Oct-3/4-Sox2 complex through the DE and SRR2 enhancers, respectively. A–E represent downstream genes, including Nanog and UTF1, that are under the control of this pluripotency transcription factor complex. Oct-3/4 also functions to repress Cdx2 gene expression in which Sox2 is probably not involved. Although not depicted in the figure, Cdx2 blocks Oct-3/4 gene expression and commits differentiation to trophoblast cell lineage. Thus, reciprocal repression between Oct-3/4 and Cdx2 appears to be involved in cell fate determination between inner cell mass cells, which are the in vivo equivalent of ES cells, and trophectoderm within the blastocyst. DE Distal enhancer, PE proximal enhancer