Editors' ChoiceDevelopment

How Wnt Signals Send Opposite Messages

Science's STKE  23 Nov 1999:
Vol. 1999, Issue 9, pp. tw4
DOI: 10.1126/stke.1999.9.tw4

A tremendous amount of information can be encoded in cellular responses to a single morphogenetic signaling molecule during development. Whangbo and Kenyon studied two neuroblast cells in Caenorhabditis elegans that move in opposite directions in response to the Wnt family member EGL-20. They show that several features of the signaling system can explain how this is accomplished. The two cells respond differently depending on the dose of EGL-20, with low doses causing anterior migration and high doses causing posterior migration. Although EGL-20 is expressed in a localized manner it does not appear to be a response to a gradient of the morphogen that produces the distinct cell fates. Rather, the two cell types have different response thresholds that result in their differential responses. Further refining the interaction is the distinction that posterior migration is signaled by a canonical Wnt pathway, whereas the anterior migration is produced by a different (currently unknown) signaling mechanism. Thus cellular responsiveness, rather than the absolute amount of the morphogen, proves to be the critical factor that determines cell fate in this system.

Whangbo, J., and Kenyon, C. (1999) A Wnt signaling system that specifies two patterns of cell migration in C. elegans. Mol. Cell 4: 851-858. [Online Journal]