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Dev Dyn 2005 Sep 01;2341:102-13. doi: 10.1002/dvdy.20523.
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Xenopus hairy2b specifies anterior prechordal mesoderm identity within Spemann's organizer.

Yamaguti M , Cho KW , Hashimoto C .

Spemann's organizer is a region of the gastrula stage embryo that contains future anterior endodermal and dorsal mesodermal tissues. During gastrulation, the dorsal mesoderm is divided into the prechordal mesoderm and the chordamesoderm. However, little is known regarding how this division is established. We analyzed the role of the anterior prechordal mesoderm-specific gene Xhairy2b in the regionalization of the organizer. We found that mesoderm-inducing transforming growth factor-beta signaling induced Xhairy2b expression. On the other hand, the ectopic expression of Xhairy2b induced the expression of organizer-specific genes and resulted in the formation of a secondary dorsal axis lacking head and notochord structures. We also showed that Xhairy2b down-regulated the expression of ventral mesodermal, anterior endodermal, and chordamesodermal genes. In Xhairy2b-depleted embryos, defects in the specification of anterior prechordal mesoderm identity were observed as the border between the prechordal mesoderm and the chordamesoderm was anteriorly shifted. These results suggest that Xhairy2b establishes the identity of the anterior prechordal mesoderm within Spemann's organizer by inhibiting the formation of neighboring tissues.

PubMed ID: 16059909
Article link: Dev Dyn

Species referenced: Xenopus
Genes referenced: admp cer1 chrd dkk1 egr2 en2 frzb fst gal.2 gsc hes4 hhex nkx2-4 nodal1 nodal2 nog not otx2 pax2 tbxt ventx1.2 ventx2.2
Morpholinos: hes4 MO4

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