Building a Brain (IMAGE)

Salk Institute

Building a Brain

Caption

Wnt and Sonic hedgehog (Shh)are signaling proteins that pattern the dorsal (D) and ventral (V) ends - the North and South poles - of the embryonic brain. Wnt and Shh are in reciprocal competition in the embryo, and they strongly repress each other's activities. Vacik et al. describe a simple yet powerful new mechanism for this reciprocal repression: the Vax transcription factors, whose expression is activated by Shh, in turn activate the expression of dnTcf7l2, which functions as a potent inhibitor of Wnt signaling. This discovery is likely to have broad implications, since the competing Shh and Wnt pathways function in many other settings in biology, including the progression of colon cancer and the development of type II diabetes.

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Courtesy of the Salk Institute for Biological Studies

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