Sonic hedgehog patterning in chick neural plate is antagonized by a Wnt3-like signal

Sonic hedgehog (Shh) patterns the dorsal-ventral axis of the neural tube by promoting the differentiation of ventral neural cell types while suppressing dorsal neural fates. Other signals impinge upon the Shh response, biasing the differentiation of a cell. Three dorsally expressed transforming Wnts, of which the most broadly expressed is Wnt3, may be among the signals that influence the Shh response. We demonstrate that activation of Wnt signaling results in an inhibition of the Shh response in neural tissue. Additionally, we show that the expression pattern of chick Wnt3 is consistent with a role in neural patterning. These results indicate that differentiating neural tube cells, besides integrating signals from Hedgehogs and BMPs, may also incorporate a Wnt response to make cell fate decisions.