Mesoderm induction by fibroblast growth factor in early Xenopus development

Area of Science:

• Developmental Biology
• Molecular Embryology
• Cell Signaling

Background:

• Mesoderm formation in early amphibian development is crucial for establishing embryonic structures.
• Endodermal signals induce mesoderm, which comprises ventral and organizer zones.
• Heparin binding growth factors (HBGFs) are implicated as potential mesoderm inducers.

Purpose of the Study:

• To identify and characterize the endogenous mesoderm-inducing factors in amphibian embryos.
• To investigate the role of fibroblast growth factors (FGFs) in mesoderm induction and differentiation.
• To explore the temporal competence of ectoderm to respond to FGFs and the underlying receptor mechanisms.

Main Methods:

• In vitro induction assays using blastula ectoderm cells with candidate HBGFs.
• Purification of inducing activity from Xenopus blastulae via heparin affinity chromatography.
• Antibody neutralization, Western blotting, and 125I-labeled ligand binding to identify and characterize the FGF receptor.

Main Results:

• Fibroblast growth factors (FGFs) and ECDGF are potent mesoderm-inducing agents in vitro.
• Endogenous inducing activity in Xenopus blastulae is identified as FGF, sufficient for ventral induction in vivo.
• Ectoderm competence to FGFs is developmentally regulated, paralleled by changes in FGF receptor binding, mediated by a ~130 kDa receptor.

Conclusions:

• FGFs are key endogenous signals for mesoderm induction in early amphibian development.
• The FGF receptor plays a critical role in mediating developmental responses to FGF signaling.
• Understanding these mechanisms provides insights into embryonic patterning and can be extended to other species, including mammals.