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Dev Biol 2013 Jun 01;3781:1-12. doi: 10.1016/j.ydbio.2013.02.024.
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Different thresholds of Wnt-Frizzled 7 signaling coordinate proliferation, morphogenesis and fate of endoderm progenitor cells.

Wnt signaling has multiple dynamic roles during development of the gastrointestinal and respiratory systems. Differential Wnt signaling is thought to be a critical step in Xenopus endoderm patterning such that during late gastrula and early somite stages of embryogenesis, Wnt activity must be suppressed in the anterior to allow the specification of foregut progenitors. However, the foregut endoderm also expresses the Wnt-receptor Frizzled 7 (Fzd7) as well as several Wnt ligands suggesting that the current model may be too simple. In this study, we show that Fzd7 is required to transduce a low level of Wnt signaling that is essential to maintain foregut progenitors. Foregut-specific Fzd7-depletion from the Xenopus foregut resulted in liver and pancreas agenesis. Fzd7-depleted embryos failed to maintain the foregut progenitor marker hhex and exhibited decreased proliferation; in addition the foregut cells were enlarged with a randomized orientation. We show that in the foregut Fzd7 signals via both the Wnt/β-catenin and Wnt/JNK pathways and that different thresholds of Wnt-Fzd7 activity coordinate progenitor cell fate, proliferation and morphogenesis.

PubMed ID: 23562607
PMC ID: PMC4263287
Article link: Dev Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: a2m actl6a casp3.2 cat.2 cdc42 cdh1 cdh3 ctnnb1 dkk1 fos fzd7 gsk3b hhex jun mapk8 pdx1 rac1 sfrp5 tbx2 ventx1.2 ventx2.2 wnt11 wnt8a
Antibodies: Cdh3 Ab1

Phenotypes: Xla Wt + BIO (fig.7.a) [+]

Article Images: [+] show captions
References [+] :
Adams, Quantitative analysis of cadherin-catenin-actin reorganization during development of cell-cell adhesion. 1997, Pubmed