Protein kinase CK2 is required for Wntless internalization and Wnt secretion

Area of Science:

• Cellular biology
• Molecular signaling
• Developmental biology

Background:

• Wnt proteins are crucial lipid-modified signaling molecules essential for development and tissue homeostasis.
• Wntless (Wls) is a transmembrane protein that mediates Wnt secretion from the endoplasmic reticulum to the cell surface.
• Wls undergoes endocytosis and recycling via the retromer complex to maintain efficient Wnt secretion.

Purpose of the Study:

• To investigate the role of protein kinase CK2 (CK2) in regulating Wnt secretion.
• To determine the evolutionary conservation of CK2's function in Wnt secretion.
• To elucidate the molecular mechanism by which CK2 affects Wntless trafficking.

Main Methods:

• Genome-wide screening in Caenorhabditis elegans to identify Wnt signaling regulators.
• Inhibition of CK2 activity in both C. elegans and mammalian cell cultures.
• Assessment of Wnt secretion and Wntless (Wls) protein localization using cellular and biochemical assays.

Main Results:

• CK2 function is required in Wnt-producing cells for efficient Wnt secretion.
• Inhibition of CK2 activity impairs Wnt5a secretion in mammalian cells, demonstrating evolutionary conservation.
• CK2 inhibition leads to increased plasma membrane localization of Wls in both C. elegans and mammalian cells.

Conclusions:

• Protein kinase CK2 plays a conserved role in regulating Wnt secretion.
• CK2 likely controls Wnt secretion by modulating Wntless internalization from the plasma membrane.
• Understanding CK2's role in Wntless trafficking offers insights into developmental and homeostatic signaling pathways.