Ubiquitin-Specific Protease 34 Inhibits Osteoclast Differentiation by RegulatingNF-κBSignaling

The ubiquitination and deubiquitination enzymes ensure the stability and proper function of most cellular proteins. Disturbance of either enzyme compromises tissue homeostasis. We recently have identified that the ubiquitin-specific protease 34 (USP34) contributes to bone formation by promoting osteogenic differentiation of mesenchymal stem cells. However, its role in bone resorption, which couples bone formation, remains unknown. Here we show that knockdown ofUsp34promotes osteoclast differentiation of RAW264.7 cells. Conditional knockout ofUsp34in bone marrow-derived macrophages (BMMs) or in osteoclasts leads to elevated osteoclast function and low bone mass. Mechanically, we identify that USP34 restrains NF-kappa B signaling by deubiquitinating and stabilizing the NF-kappa B inhibitor alpha (I kappa B alpha). Overexpression ofI kappa B alpha represses osteoclastic hyperfunction ofUsp34-deficient RAW264.7 cells. Collectively, our results show that USP34 inhibits osteoclastogenesis by regulating NF-kappa B signaling. (c) 2020 American Society for Bone and Mineral Research.