Frizzled-7 signalling controls tissue separation during Xenopus gastrulation

Area of Science:

• Developmental Biology
• Cell Signaling
• Molecular Biology

Background:

• Frizzled (Fz) receptors mediate complex cell signaling in metazoans.
• Fz-dependent pathways regulate embryonic axis formation and cell polarization.
• Distinct Wnt ligands, Fz isoforms, and cellular context dictate pathway activation.

Purpose of the Study:

• To investigate a novel Frizzled-dependent signaling cascade.
• To identify Fz signaling pathways independent of Dishevelled.
• To elucidate the role of Fz/PKC signaling in vertebrate embryonic development.

Main Methods:

• Utilized Xenopus laevis embryos as a model system.
• Investigated Frizzled-7 (Fz7) signaling.
• Examined the roles of trimeric G proteins and protein kinase C (PKC).
• Assessed the effects of Fz7 loss-of-function on gastrulation.

Main Results:

• Identified a Dishevelled-independent Fz signaling branch involving G proteins and PKC.
• Demonstrated that Fz7-dependent PKC signaling regulates mesodermal cell sorting during gastrulation.
• Showed that loss of zygotic Fz7 function impairs anterior mesoderm separation from ectoderm, causing gastrulation defects.

Conclusions:

• A novel Fz/PKC signaling pathway plays a critical role in vertebrate gastrulation.
• This pathway is essential for controlling cell-sorting behaviors in the mesoderm.
• Provides the first in vivo evidence for the developmental relevance of the Fz/PKC pathway in vertebrates.