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Wnt and FGF pathways cooperatively pattern anteroposterior neural ectoderm in Xenopus
L L McGrew1, S Hoppler, R T Moon
1Howard Hughes Medical Institute and Department of Pharmacology, University of Washington School of Medicine, Seattle 98195, USA.
Mechanisms of Development
|March 5, 1998
Summary
Loss-of-function studies in Xenopus reveal Wnt signaling is crucial for neural ectoderm patterning. Wnt and FGF pathways cooperate to establish the complete anteroposterior neural pattern.
Area of Science:
- Developmental biology
- Molecular biology
- Neuroscience
Background:
- Gain-of-function studies showed Xwnt-3a patterns neural tissue by altering anterior and posterior neural gene expression.
- No prior loss-of-function studies confirmed endogenous Wnt signaling's role in neural ectoderm anteroposterior patterning.
Purpose of the Study:
- To investigate the requirement of endogenous Wnt signaling for neural ectoderm patterning along the anteroposterior axis in Xenopus.
- To elucidate the interplay between Wnt and FGF signaling pathways in neural pattern formation.
Main Methods:
- Utilized dominant-negative Wnt expression in Xenopus embryos to assess loss-of-function effects.
- Employed noggin-treated explants to study the dependency of Xwnt-3a and FGF on signaling pathways.
Main Results:
- Dominant-negative Wnt caused reduced posterior and elevated anterior neural gene expression, confirming Wnt's role.
- Xwnt-3a's effect on anterior genes required FGF signaling, but posterior gene effects did not.
- FGF's ability to elevate posterior gene expression depended on endogenous Wnt signaling.
Conclusions:
- Neural induction is initially Wnt-independent.
- Complete anteroposterior neural pattern formation requires the cooperative action of Wnt and FGF signaling pathways.