Nrf2 dynamically regulates RANKL-induced osteoclastogenesis and cathepsin K function.
Speck-Hernandez Cesar A, de Souza Furtado Taíssa C, de Souza Laisa Y, da Silva Keteryne R, Lucena Silva Gabriel V, Gonzalez Osuna Luis G, Publio Gabriel A, Schneider Ayda, Melo Paulo H, Scalice-Chiari Gabriella, Alves-Filho Jose Carlos, de Queiroz Cunha Fernando, Cunha Thiago Mattar, Fukada Sandra Yasuyo
Abstract
Osteoclasts mediate bone resorption primarily through the protease Cathepsin K. RANKL, the master cytokine driving osteoclastogenesis, elevates reactive oxygen species (ROS) levels that promote osteoclast differentiation; however, excessive ROS can lead to oxidative stress and cellular damage. To counteract the detrimental effects of ROS, osteoclasts activate antioxidant defense mechanisms, including the Nrf2 pathway. Here, we identify that antioxidant responses are dynamically regulated during osteoclastogenesis and osteoclast activation. Through a combined bioinformatic and genetic approach using engineered mouse models, we demonstrate a dual role of RANKL in regulating antioxidant responses in osteoclasts: while it suppresses glutathione-mediated antioxidant defenses, RANKL activates Nrf2-dependent mechanisms during osteoclast differentiation. Genetic deletion of Nrf2 in vitro enhances osteoclast formation, whereas impairs osteoclast resorptive function, reducing cathepsin K activity. Nrf2-deficient osteoclasts exhibit increased lipid peroxidation, mitochondrial dysfunction, and lysosomal instability without alterations in cell viability. Together, these findings identify Nrf2 as a critical regulator of osteoclast function, essential for maintaining redox balance and lysosomal integrity during bone resorption. This study reveals an intricate interplay between RANKL-induced oxidative signaling and antioxidant regulation, highlighting Nrf2 as a critical determinant of osteoclast-mediated bone resorption.
Key Findings
- RANKL regulates antioxidant responses in osteoclasts by suppressing glutathione-mediated defenses while activating Nrf2-dependent mechanisms.
- Genetic deletion of Nrf2 enhances osteoclast formation but impairs resorptive function by reducing cathepsin K activity.
- Nrf2-deficient osteoclasts show increased lipid peroxidation, mitochondrial dysfunction, and lysosomal instability without affecting cell viability.
Clinical Significance
Understanding Nrf2's role in maintaining redox balance and lysosomal integrity during osteoclast-mediated bone resorption may inform therapeutic strategies for bone diseases involving abnormal osteoclast activity.
Citation
Speck-Hernandez Cesar A, de Souza Furtado Taíssa C, de Souza Laisa Yet al.. Nrf2 dynamically regulates RANKL-induced osteoclastogenesis and cathepsin K function. The Journal of biological chemistry. 2026-Jun-19.