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XB-ART-11800
Genes Dev December 1, 1999; 13 (23): 3149-59.

Wnt signaling in Xenopus embryos inhibits bmp4 expression and activates neural development.

Baker JC , Beddington RS , Harland RM .


Abstract
We report a new role for Wnt signaling in the vertebrate embryo: the induction of neural tissue from ectoderm. Early expression of mouse wnt8, Xwnt8, beta-catenin, or dominant-negative GSK3 induces the expression of neural-specific markers and inhibits the expression of Bmp4 in Xenopus ectoderm. We show that Wnt8, but not the BMP antagonist Noggin, can inhibit Bmp4 expression at early gastrula stages. Furthermore, inhibition of beta-catenin activity in the neural ectoderm of whole embryos by a truncated TCF results in a decrease in neural development. Therefore, we suggest that a cleavage-stage Wnt signal normally contributes to an early repression of Bmp4 on the dorsal side of the embryo and sensitizes the ectoderm to respond to neural inducing signals from the organizer. The Wnt targets Xnr3 and siamois have been shown previously to have neuralizing activity when overexpressed. However, antagonists of Wnt signaling, dnXwnt8 and Nxfrz8, inhibit Wnt-mediated Xnr3 and siamois induction, but not neural induction, suggesting an alternative mechanism for Bmp repression and neuralization. Conversely, dnTCF blocks both Wnt-mediated Xnr3 and neural induction, suggesting that both pathways require this transcription factor.

PubMed ID: 10601040
PMC ID: PMC317181
Article link: Genes Dev
Grant support: [+]
Genes referenced: acta4 actc1 actl6a ag1 bmp4 bmpr1a ctnnb1 eef1a2 egr2 frzb fzd5 fzd8 gsk3b ncam1 nodal3.1 nodal3.2 nog nrp1 sia1 tbxt wnt3a wnt8a


Article Images: [+] show captions
References:
Axelrod, 1998, Pubmed, Xenbase [+]


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