RANKL promotes MT2 degradation and ROS production in osteoclast precursors through Beclin1-dependent autophagy

Area of Science:

• Cell Biology
• Biochemistry
• Bone Biology

Background:

• Reactive oxygen species (ROS) are critical for osteoclast differentiation.
• Metallothionein (MT), particularly MT2, scavenges ROS and influences osteoclast formation.
• Autophagy, promoted by RANKL, degrades cellular components, suggesting a link with MT2 and ROS.

Purpose of the Study:

• To investigate the interplay between RANKL-dependent autophagy, MT2, and ROS in osteoclast differentiation.
• To explore the therapeutic potential of MT2 in RANKL-related bone loss.

Main Methods:

• In vitro RANKL administration and RANKL-overexpressing (Tg-RANKL) mice models.
• Assessment of ROS production, MT2 expression, Beclin1, and autophagic activity in osteoclast precursors (OCPs).
• Utilized Spautin1 to study Beclin1-dependent autophagy and MT2 regulation; employed MT2-cDNA-AAVs for therapeutic assessment.

Main Results:

• RANKL increased ROS production and Beclin1 expression while decreasing MT2 protein levels in OCPs.
• Inhibition of Beclin1 with Spautin1 reduced RANKL-induced ROS and osteoclast differentiation, restoring MT2 levels.
• MT2 overexpression via AAVs attenuated ROS production and osteoclastogenesis in Tg-RANKL mice, ameliorating bone loss.

Conclusions:

• RANKL reduces MT2 protein expression through Beclin1-dependent autophagy, subsequently enhancing ROS production and osteoclast differentiation.
• Targeting MT2 via overexpression presents a potential therapeutic strategy for RANKL-related bone loss conditions.