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XB-ART-51516
Wiley Interdiscip Rev Dev Biol March 1, 2016; 5 (2): 150-68.

Specification of anteroposterior axis by combinatorial signaling during Xenopus development.

Carron C , Shi DL .


Abstract
The specification of anteroposterior (AP) axis is a fundamental and complex patterning process that sets up the embryonic polarity and shapes a multicellular organism. This process involves the integration of distinct signaling pathways to coordinate temporal-spatial gene expression and morphogenetic movements. In the frog Xenopus, extensive embryological and molecular studies have provided major advance in understanding the mechanism implicated in AP patterning. Following fertilization, cortical rotation leads to the transport of maternal determinants to the dorsal region and creates the primary dorsoventral (DV) asymmetry. The activation of maternal Wnt/ß-catenin signaling and a high Nodal signal induces the formation of the Nieuwkoop center in the dorsal-vegetal cells, which then triggers the formation of the Spemann organizer in the overlying dorsal marginal zone. It is now well established that the Spemann organizer plays a central role in building the vertebrate body axes because it provides patterning information for both DV and AP polarities. The antagonistic interactions between signals secreted in the Spemann organizer and the opposite ventral region pattern the mesoderm along the DV axis, and this DV information is translated into AP positional values during gastrulation. The formation of anterior neural tissue requires simultaneous inhibition of zygotic Wnt and bone morphogenetic protein (BMP) signals, while an endogenous gradient of Wnt, fibroblast growth factors (FGFs), retinoic acid (RA) signaling, and collinearly expressed Hox genes patterns the trunk and posterior regions. Collectively, DV asymmetry is mostly coupled to AP polarity, and cell-cell interactions mediated essentially by the same regulatory networks operate in DV and AP patterning. For further resources related to this article, please visit the WIREs website.

PubMed ID: 26544673
Article link: Wiley Interdiscip Rev Dev Biol

Genes referenced: admp aldh1a2 bambi bmi1 bmp2 bmp4 bmp7.1 bmp7.2 bmper cdx4 cer1 chrd.1 dkk1 ezh2 foxa4 foxd3 frzb fst gsc hoxa1 hoxa7 hoxa9 hoxb9 hoxd1 lhx1 ncoa6 nodal nodal1 nodal3.1 nog not olfm1 otx2 prc1 ripply3 sia1 sia2 tbxt tll1 twsg1 vegt ventx1.1 ventx1.2 wnt11 wnt8a wnt8b


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