Fig. 2.

Crucial cell fate decisions in intestinal epithelium. The choice between absorptive enterocytes (Ent) and secretory (Sec) cells is enacted in transient bipotential progenitor (Bi-Pro) cells very soon after intestinal stem cells (ISCs) leave the stem-cell compartment. This cell fate decision depends on signaling from cell-bound ligands of the Delta family to adjoining cells that carry Notch-family receptors. Notch signaling activates the transcriptional repressor Hes1, which tightly represses expression of the transcription factor (TF) gene Atoh1. Delta-positive cells increase Atoh1 expression and adopt the Sec fate, while Atoh1-negative cells become enterocytes. [Adapted with permission from T.-H. Kim et al., Nature 506: 511–515, 2014.] Examples of TFs enriched in ISCs and different epithelial progenitors (Pro) are listed in Table 2.