Canonical Wnt signalling activates TAZ through PP1A during osteogenic differentiation

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• TAZ is a key transcriptional modulator regulating cell proliferation, differentiation, and stem cell self-renewal.
• TAZ activity is influenced by Hippo, GPCR, and Wnt signaling pathways, but its precise activation mechanisms remain unclear.

Purpose of the Study:

• To investigate the role of canonical Wnt signaling in regulating TAZ activity during osteogenic differentiation.
• To elucidate the molecular mechanisms by which Wnt signaling controls TAZ activation and subsequent osteoblast differentiation.

Main Methods:

• Utilized Wnt3a stimulation and GSK3β inhibition to study TAZ regulation.
• Employed siRNA to deplete PP1A and assess its impact on TAZ stabilization.
• Analyzed TAZ expression, dephosphorylation, nuclear localization, and its role in osteogenic differentiation.

Main Results:

• Wnt3a stimulation increased TAZ expression and promoted its dephosphorylation, leading to stabilization and nuclear translocation.
• PP1A was identified as the phosphatase responsible for TAZ dephosphorylation; its depletion inhibited Wnt3a-induced TAZ stabilization.
• Wnt3a-induced TAZ activation was essential for osteoblastic differentiation, as TAZ depletion reduced Wnt3a-mediated osteogenesis.

Conclusions:

• TAZ mediates Wnt3a-stimulated osteogenic differentiation through the PP1A phosphatase.
• These findings reveal that Wnt signaling regulates the Hippo pathway via TAZ, impacting osteoblast differentiation.