PRDX6 attenuates osteoporotic bone loss by restraining oxidative stress-associated osteoblast senescence.

Osteoporosis (OP) is characterized by excessive bone resorption and defective bone formation, with its pathogenesis closely linked to oxidative stress. Peroxiredoxin 6 (PRDX6) is a multifunctional enzyme with peroxidase and aiPLA2 activities, yet its contribution to osteoporotic bone loss remains insufficiently defined. This study aims to investigate the role and mechanisms of PRDX6 in alleviating OP. In ovariectomized (OVX) mice, PRDX6 levels were reduced in plasma and femoral tissue and correlated with osteoporotic changes. In MC3T3-E1 cells challenged with tert-butyl hydroperoxide (tert-BHP), PRDX6 knockdown increased ROS accumulation, enhanced senescence-associated secretory phenotype, and impaired osteogenic function, whereas PRDX6 overexpression attenuated oxidative stress-associated senescence and preserved osteogenic potential. In parallel, PRDX6 knockdown promoted osteoclast differentiation in RAW264.7 cells and BMMs, and OB-OC co-culture supported a paracrine contribution. RNA-seq highlighted cAMP pathways, and PRDX6 modulation altered intracellular cAMP with corresponding changes in PKA and CREB phosphorylation. Pharmacological and genetic perturbations supported a functional requirement for cAMP/PKA/CREB signaling in PRDX6-dependent osteogenic maintenance. Notably, in PRDX6 knockdown osteoblasts, mutant-rescue with PRDX6-WT restored cAMP signaling and osteogenic gene expression, whereas the peroxidase-deficient mutant C47S failed to rescue and the aiPLA2-deficient mutant D140A largely retained rescue capacity. Collectively, these findings identify PRDX6 as a protective regulator in OP and suggest that peroxidase-active PRDX6 may limit oxidative stress-associated senescence while preserving osteoblast function.