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Updated: Aug 4, 2026
Polarized Translocation of Fluorescent Proteins in Xenopus Ectoderm in Response to Wnt Signaling
Published on: May 26, 2011
Xwnt-8 modifies the character of mesoderm induced by bFGF in isolated Xenopus ectoderm
J L Christian1, D J Olson, R T Moon
1Department of Pharmacology, University of Washington School of Medicine, Seattle 98195.
Abstract:
In Xenopus, growth factors of the TGF-beta, FGF and Wnt oncogene families have been proposed to play a role in generating embryonic pattern. In this paper we examine potential interactions between the bFGF and Xwnt-8 signaling pathways in the induction and dorsal-ventral patterning of mesoderm. Injection of Xwnt-8 mRNA into 2-cell Xenopus embryos does not induce mesoderm formation in animal cap ectoderm isolated from these embryos at the blastula stage, but alters the response of this tissue to mesoderm induction by bFGF. While animal cap explants isolated from non-injected embryos differentiate to form ventral types of mesoderm and muscle in response to bFGF, explants from Xwnt-8 injected embryos form dorsal mesodermal and neural tissues in response to the same concentration of bFGF, even if the ectoderm is isolated from the prospective ventral sides of embryos or from UV-ventralized animals. Our results support a model whereby dorso-ventral mesodermal patterning can be attained by a single mesoderm inducing agent, possibly bFGF, which is uniformly distributed across the prospective dorsal-ventral axis, and which acts in concert with a dorsally localized signal, possibly a Wnt protein, which either alters the response of ectoderm to induction or modifies the character of mesoderm after its induction.
Insights
Basic fibroblast growth factor (bFGF) and Wnt signaling pathways interact to pattern embryonic mesoderm in Xenopus. Wnt signaling modifies ectoderm
Area of Science:
- Developmental Biology
- Molecular Embryology
- Signal Transduction
Background:
- Transforming growth factor-beta (TGF-β), fibroblast growth factor (FGF), and Wnt oncogene families are implicated in Xenopus embryonic patterning.
- Understanding interactions between signaling pathways is crucial for deciphering mesoderm induction and patterning mechanisms.
Purpose of the Study:
- To investigate the interplay between basic fibroblast growth factor (bFGF) and Xwnt-8 signaling pathways.
- To elucidate their roles in mesoderm induction and dorsal-ventral patterning in Xenopus embryos.
Main Methods:
- Injection of Xwnt-8 mRNA into 2-cell Xenopus embryos.
- Isolation and culture of animal cap explants at the blastula stage.
- Treatment of explants with bFGF to assess mesoderm induction and patterning.
Main Results:
- Xwnt-8 mRNA injection alone did not induce mesoderm in isolated animal caps.
- Xwnt-8 altered the response of animal cap ectoderm to bFGF-mediated mesoderm induction.
- Explants from Xwnt-8 injected embryos formed dorsal mesodermal and neural tissues in response to bFGF, unlike ventral tissues from controls.
Conclusions:
- A model is proposed where a uniformly distributed bFGF acts with a dorsally localized Wnt signal (possibly Xwnt-8) for dorsal-ventral mesodermal patterning.
- Wnt signaling may modify ectodermal response to induction or alter mesoderm character post-induction.
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