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Updated: Aug 8, 2026
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Tissue Determination Using the Animal Cap Transplant (ACT) Assay in Xenopus laevis
Published on: May 17, 2010
Competition between noggin and bone morphogenetic protein 4 activities may regulate dorsalization during Xenopus
Y Re'em-Kalma1, T Lamb, D Frank
1Department of Biochemistry, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa.
Summary
Bone morphogenetic protein 4 (BMP-4) inhibits dorsal mesoderm formation in Xenopus embryos. BMP-4 and noggin compete to regulate mesoderm patterning and muscle formation, defining tissue boundaries.
Area of Science:
- Developmental Biology
- Molecular Biology
- Xenopus Embryology
Background:
- Bone morphogenetic protein 4 (BMP-4) is known to induce ventral mesoderm.
- Dorsal mesoderm formation, including the Spemann organizer, is crucial for embryonic patterning.
- The interplay between BMP-4 and dorsalizing signals is not fully understood.
Purpose of the Study:
- To investigate the role of BMP-4 in dorsal mesoderm formation and dorsalization.
- To elucidate the interaction between BMP-4 and noggin in mesoderm patterning.
- To understand how BMP-4 influences the response of ventral mesoderm to dorsalization signals.
Main Methods:
- Ectopic expression of BMP-4 RNA in Xenopus embryos and animal cap explants.
- Quantitative analysis of gene transcription (goosecoid, forkhead-1, Xbra, Xwnt-8, etc.).
- Treatment of ventral marginal zone explants with noggin protein and juxtaposition with Spemann organizer.
Main Results:
- BMP-4 overexpression repressed dorsal mesoderm markers (goosecoid, forkhead-1) and induced ventral markers (Xbra, Xwnt-8).
- BMP-4 ventralized the Spemann organizer and impaired its ability to dorsalize ventral mesoderm.
- BMP-4 inhibited the muscle-forming response of ventral mesoderm to noggin and Spemann organizer signals.
- Noggin treatment downregulated endogenous BMP-4 transcripts in dorsalized ventral marginal zone explants.
Conclusions:
- BMP-4 actively represses dorsal mesoderm formation and inhibits dorsalization signals in Xenopus.
- Noggin antagonizes BMP-4 activity and downregulates BMP-4 expression during dorsalization.
- A competitive interaction between BMP-4 and noggin regulates the extent of dorsalization and mesoderm patterning.
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