PTK7 modulates Wnt signaling activity via LRP6

Area of Science:

• Developmental Biology
• Cell Signaling
• Molecular Embryology

Background:

• Protein tyrosine kinase 7 (PTK7) is a transmembrane receptor crucial for vertebrate embryonic development.
• PTK7 is known to regulate planar cell polarity (PCP) pathways, affecting cell movements like convergent extension (CE).

Purpose of the Study:

• To investigate the role of PTK7 in canonical Wnt/β-catenin signaling.
• To elucidate the relationship between PTK7, LRP6, and Wnt signaling pathways in embryonic development.

Main Methods:

• PTK7 protein knockdown in Xenopus embryos.
• Analysis of Wnt/β-catenin activity and meis3 gene expression.
• Assessment of LRP6 protein levels and PTK7-LRP6 interaction.

Main Results:

• PTK7 knockdown inhibits Wnt/β-catenin signaling and meis3 expression, impacting posterior tissue specification and CE.
• PTK7 depletion reduces LRP6 protein levels, affecting both canonical and noncanonical Wnt activities.
• PTK7 physically interacts with LRP6, suggesting a regulatory mechanism.

Conclusions:

• PTK7 acts as a novel modulator of LRP6, influencing Wnt signaling pathways.
• PTK7 plays a critical role in balancing canonical Wnt/β-catenin and noncanonical Wnt/PCP activities during embryogenesis.