G-Alpha Subunit Abundance and Activity Differentially Regulate β-Catenin Signaling

Area of Science:

• Cellular signaling
• Molecular biology
• Biochemistry

Background:

• Heterotrimeric G proteins are crucial signal transducers.
• G proteins influence β-catenin signaling, but this link is debated and context-specific.
• Understanding G protein-β-catenin interactions is key to deciphering cellular regulation.

Purpose of the Study:

• To investigate the specific roles of G-alpha subunits in regulating β-catenin signaling.
• To elucidate the context-dependent nature of G protein regulation of β-catenin.

Main Methods:

• Utilized genetic knockout and knockdown of G-alpha subunits.
• Employed Pasteurella multocida toxin (PMT) for G-protein activation.
• Used LiCl as a β-catenin signaling agonist in HEK293T cells and mouse embryo fibroblasts.

Main Results:

• PMT significantly enhanced LiCl-induced active β-catenin levels.
• Gq/11 and G12/13 knockout cells exhibited higher active and total β-catenin.
• PMT/LiCl-stimulated β-catenin was abolished by G12/13 knockdown, but not Gq knockdown.

Conclusions:

• Endogenous G-alpha proteins act as negative regulators of active β-catenin.
• PMT-activated G-alpha subunits positively regulate LiCl-induced β-catenin in a G12/13-dependent manner.
• G-alpha subunit regulation of β-catenin is context-dependent.