Notch2 signaling promotes osteoclast resorption via activation of PYK2

Area of Science:

• Cell Biology
• Skeletal Biology
• Signaling Pathways

Background:

• Notch signaling is crucial for cell fate decisions and skeletal development.
• Its role in osteoclast differentiation and resorption activity is increasingly recognized.
• The precise mechanisms linking Notch signaling to osteoclast resorption require further investigation.

Purpose of the Study:

• To investigate the specific role of Notch signaling in osteoclast resorption activity.
• To elucidate the molecular pathways involved in Notch-mediated control of osteoclast function.

Main Methods:

• Utilized the gamma-secretase inhibitor dibenzazepine (DBZ) to attenuate Notch signaling in osteoclasts.
• Assessed the expression of key osteoclast differentiation factors like NFATc1.
• Examined the activation of PYK2, c-Src/PYK2 interaction, and microtubule acetylation.
• Employed an in vivo interleukin-1-induced bone loss model.

Main Results:

• DBZ treatment suppressed NFATc1 expression and PYK2 autophosphorylation, impairing podosome belt and sealing zone formation.
• RANKL stimulation enhanced PYK2 activation and NICD2 production in osteoclasts.
• Overexpression of NICD2 rescued DBZ-induced suppression of resorption activity, promoting PYK2 activation and microtubule acetylation.
• DBZ significantly reduced bone destruction in the in vivo bone loss model.

Conclusions:

• Notch2 signaling in osteoclasts regulates resorption activity through the PYK2-c-Src-microtubule pathway.
• Targeting Notch signaling may offer a therapeutic strategy for conditions involving excessive bone resorption.