Figure 3.
Tcf3 is an integral component of the core regulatory circuitry of ES cells. (A) Tcf3 forms an interconnected autoregulatory loop with Oct4, Sox2, and Nanog. Proteins are represented by ovals and genes are indicated by rectangles. (B) Model showing a key portion of the regulatory circuitry of mES cells where Oct4, Sox2, Nanog, and Tcf3 occupy both active and silent genes. The evidence that Oct4, Nanog, and Tcf3 occupy these genes is described here; Sox2 occupancy is inferred from previous studies in human ES cells (Boyer et al. 2005). Evidence that the transcriptionally silent genes are occupied by Polycomb Repressive Complexes is from Boyer et al. (2006), and unpublished data and that these genes have stalled RNA polymerases is from Guenther et al. (2007) and Stock et al. (2007). Proteins are represented by ovals and genes are indicated by rectangles.