(A) In C. elegans embryos, ztf-11 is expressed broadly in early progenitors (ztf-11+). These early progenitors subsequently differentiate to produce neuronal progenitors (in which expression of ztf-11 is maintained, thus repressing epithelial and muscle fates) and epithelial/muscle cells (which do not express ztf-11). The neuronal progenitors can differentiate to produce neurons or other cell types such as epithelial or muscle cells. Once neurons fully differentiate (pale blue at the bottom of the figure), they no longer express ztf-11. The mechanisms responsible for the repression of epithelial and muscle fates in these cells are not understood. (B) In C. elegans larvae, ztf-11 is not initially present in neuro-epithelial precursors or epithelial cells that eventually transdifferentiate into neurons. ztf-11 is turned on by pro-neural factors in differentiating neurons, where it represses epithelial fates. Differentiated neurons lack ztf-11 suggesting that other unknown factors take on the role of repression (bottom image).
Image credit: P Sivaramakrishnan and J I Murray