A peroxiredoxin 1-reactive oxygen species feedback loop modulates nuclear factor kappa B activity in osteoclastogenesis.

Osteoclastogenesis is driven by tightly coordinated transcriptional programs downstream of receptor activator of nuclear factor-κB ligand (RANKL) signaling, in which reactive oxygen species (ROS) function as essential secondary messengers. Although extracellular peroxiredoxin 1 (PRDX1) has been implicated in the suppression of osteoclast differentiation, the role of intracellular PRDX1 in regulating osteoclastogenic signaling remains poorly understood. Here, we identify intracellular PRDX1 as a redox-sensitive negative regulator of osteoclastogenesis and bone resorption. PRDX1 deficiency markedly enhanced osteoclast differentiation, bone resorption activity, and osteoporotic phenotypes in vivo. Transcriptomic and mechanistic analyses revealed that PRDX1 attenuates osteoclastogenic gene transcription by blocking the nuclear factor kappa B (NF-κB)/p65 signaling axis. Loss of PRDX1 increased intracellular ROS accumulation, promoted p65 nuclear translocation and promoter occupancy, thereby amplifying osteoclastogenic transcriptional programs. Mechanistically, PRDX1 underwent TNF receptor associated factor 6 (TRAF6)-mediated Lys67-dependent ubiquitylation and lysosomal degradation in response to RANKL signaling. In addition, RANKL-induced Src activation promoted phosphorylation of PRDX1 at Tyr194, which enhanced TRAF6-mediated ubiquitylation without substantially altering overall TRAF6 binding. Together, these findings reveal a PRDX1-ROS feedback loop that modulates NF-κB activity during osteoclastogenesis and identify regulated PRDX1 degradation as a mechanism by which RANKL signaling amplifies osteoclastogenic responses. These findings establish intracellular PRDX1 as an important modulator of skeletal homeostasis, suggesting its potential relevance as a pharmacological target in diseases characterized by excessive bone resorption.