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EMBO J 1996 Sep 02;1517:4547-55.
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Endoderm induction by the organizer-secreted factors chordin and noggin in Xenopus animal caps.

Sasai Y , Lu B , Piccolo S , De Robertis EM .

Spemann's organizer has potent neural inducing and mesoderm dorsalizing activities in the Xenopus gastrula. A third activity, the organizer's ability to induce a secondary gut, has been difficult to analyze experimentally due to the lack of early gene markers. Here we introduce endodermin, a pan-endodermal gene marker, and use it to demonstrate that chordin (Chd), a protein secreted by the organizer region, is able to induce endodermal differentiation in Xenopus. The ability of chd, as well as that of noggin, to induce endoderm in animal cap explants is repressed by the ventralizing factor BMP-4. When FGF signaling is blocked by a dominant-negative FGF receptor in chd-injected animal caps, neural induction is inhibited and most of the explant is induced to become endoderm. The results suggest that proteins secreted by the organizer, acting together with known peptide growth factors, regulate differentiation of the endodermal germ layer.

PubMed ID: 8887546
PMC ID: PMC452184

Grant support: [+]

Species referenced: Xenopus
Genes referenced: a2m chrd nog

References [+] :
Amaya, Expression of a dominant negative mutant of the FGF receptor disrupts mesoderm formation in Xenopus embryos. 1991, Pubmed, Xenbase