Nrf2 differentially regulates osteoclast and osteoblast differentiation for bone homeostasis.

Nuclear factor erythroid-derived factor 2-related factor 2 (Nrf2) is a master regulator of antioxidant response and protects cells from excessive oxidative stress. Nrf2 emerges as a prospective therapeutic target for metabolic bone disorders, in which the balance between osteoblastic bone formation and osteoclastic bone resorption is disrupted. However, the molecular mechanism through which Nrf2 modulates bone homeostasis remains unclear. In this study, we compared the differences in Nrf2-mediated antioxidant response and ROS regulation in osteoblasts and osteoclasts, both in vitro and in vivo. Findings indicated a close connection between the Nrf2 expression and its related antioxidant response with osteoclasts than osteoblasts. We next pharmacologically manipulated the Nrf2-mediated antioxidant response during osteoclast or osteoblast differentiation. Nrf2 inhibition enhanced osteoclastogenesis, while its activation suppressed it. In contrast, osteogenesis decreased irrespective of whether Nrf2 was inhibited or activated. These findings highlight the distinct ways in which the Nrf2-mediated antioxidant response regulates osteoclast and osteoblast differentiation, thereby contributing to the development of Nrf2 targeted therapies for metabolic bone diseases. • The Nrf2-induced antioxidant response is more actively regulated in osteoclasts than in osteoblasts, both in vitro and in vivo. • ROS plays a critical role in osteoclastogenesis regulated by Nrf2. • Pharmacological inhibition of Nrf2 by ML385 leads to increased osteoclastogenesis and decreased osteogenesis. • Pharmacological activation of Nrf2 by curcumin leads to a decrease in both osteoclastogenesis and osteogenesis. [ABSTRACT FROM AUTHOR]