Henrique, D., Tyler, D., Kintner, C., Heath, J.K., Lewis, J.H., Ish-Horowitz, D., Storey, K.G. (1997). cash4, a novel achaete-scute homolog induced by Hensen's node during generation of the posterior nervous system.  Genes Dev. 11(5): 603--615.

FBrf0093508

Research paper

In vertebrate embryos, the precursor cells of the central nervous system (CNS) are induced by signaling from the organizer region. Here we report the isolation of a novel vertebrate achaete-scute homolog, cash4, which is expressed in the presumptive posterior nervous system in response to such signaling. cash4 is first expressed in epiblast cells flanking the late-phase organizer (Hensen's node), which retains its ability to induce cash4 during regression to the caudal end of the embryo. We show that these node-derived signals can be mimicked in vivo by the activity of fibroblast growth factor (FGF). We demonstrate that cash4 can substitute for the achaete/scute genes in the fly and that it also has proneural activity in vertebrate embryos. Together these results suggest that cash4 functions as a proneural gene downstream of node-derived signals (including FGF) to promote the formation of the neural precursors that will give rise to the posterior CNS in the chick embryo.