Specification of the anteroposterior neural axis through synergistic interaction of the Wnt signaling cascade with noggin and follistatin.

Embryological data and the activities of the neural-inducing factors noggin and follistatin are consistent with the hypothesis that the nervous system is initially induced with an anterior character, with subsequent signals imparting posterior pattern. We report that Xwnt3a is a candidate for involvement in anteroposterior neural patterning, as it synergizes with the neural-inducing factors noggin and follistatin to increase the expression of posterior neural genes. Furthermore we show that beta-catenin, an intracellular protein implicated in the Wnt signal transduction cascade, mimics the activity of Xwnt3a. These data suggest that the generation of pattern within the vertebrate nervous system may rely on synergism between a Wnt signaling pathway and multiple neural-inducing factors.