Wnt5b-Ryk pathway provides directional signals to regulate gastrulation movement

Area of Science:

• Developmental Biology
• Cell Signaling

Background:

• Noncanonical Wnt proteins typically act as permissive cues for cell movement, often through Frizzled (Fz) receptors.
• Wnt ligands also signal via the receptor tyrosine kinase-like orphan receptor (Ryk), but its role in embryogenesis is less understood.

Purpose of the Study:

• To investigate the role of Wnt5b and its receptor Ryk in regulating cell movements during vertebrate gastrulation.
• To elucidate the signaling mechanisms by which Wnt5b-Ryk influences embryonic development.

Main Methods:

• Utilized zebrafish as a model organism to study Wnt-Ryk signaling in vivo.
• Employed co-culture assays to establish directional Wnt5b gradients.
• Analyzed calcium (Ca2+) activity and cell protrusion dynamics in response to Wnt5b stimulation.

Main Results:

• Ryk deficiency in zebrafish disrupted Wnt5b-induced Ca2+ signaling and directional cell migration during gastrulation.
• Wnt5b-Ryk signaling was found to promote polarized cell protrusions.
• Frizzled 2 (Fz2), but not Ryk, recruited Dishevelled upon Wnt5b stimulation, indicating distinct signaling pathways.
• Ryk-expressing cells exhibited directed migration away from Wnt5b sources in co-culture experiments.

Conclusions:

• Wnt5b functions as an instructive cue, directing cell migration during gastrulation through Ryk.
• The Wnt5b-Ryk pathway plays a critical role in establishing directional cell movement essential for embryonic development.
• Full-length Ryk mediates directional Wnt5b signaling during the gastrulation process.