Sirt6 cooperates with Blimp1 to positively regulate osteoclast differentiation

Area of Science:

• Molecular biology
• Cell biology
• Bone biology

Background:

• Sirtuin 6 (Sirt6) deficiency in mice causes osteopenia with low bone turnover.
• The role of Sirt6 in osteoclast differentiation remains unclear.

Purpose of the Study:

• To investigate the function of Sirt6 in regulating osteoclast differentiation.
• To elucidate the molecular mechanisms by which Sirt6 controls osteoclastogenesis.

Main Methods:

• Targeted ablation of Sirt6 in hematopoietic cells and osteoclast precursors.
• Overexpression of Sirt6 in osteoclast precursor cells.
• Analysis of gene expression and protein interactions involving Sirt6, Blimp1, and Mafb.
• Assessment of osteoclast formation and bone volume in Sirt6-manipulated mice.

Main Results:

• Sirt6 directly represses anti-osteoclastogenic gene expression.
• Ablation of Sirt6 in hematopoietic cells decreased osteoclast numbers and increased bone volume.
• Sirt6 overexpression enhanced osteoclast formation.
• Sirt6-deficient osteoclast precursors showed impaired differentiation.
• Sirt6 forms a complex with Blimp1 to negatively regulate Mafb expression, induced by RANKL-NFATc1 signaling.

Conclusions:

• Sirt6 is a novel transcriptional repressor that negatively regulates osteoclast differentiation.
• Sirt6 plays a critical role in controlling osteoclastogenesis through the regulation of specific anti-osteoclastogenic genes.
• Targeting Sirt6 may offer a therapeutic strategy for bone disorders characterized by excessive bone resorption.