Cyclin-dependent kinase inhibitor-1 deficiency enhances bone destruction in a mouse model of arthritis.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41438476.
- Also identified by DOI 10.1016/j.bonr.2025.101892 and PMC identifier 12720362.
- Licence recorded as CC BY-NC.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Rheumatoid arthritis (RA) causes bone destruction by activating inflammatory cytokines and osteoclasts. Cyclin-dependent kinase inhibitor 1 (p21), a cell cycle regulator, may influence this process; however, its role remains unclear. Therefore, we investigated the effect and potential mechanisms of p21 deficiency in bone loss in a mouse model of arthritis. Collagen antibody-induced arthritis (CAIA) was established in p21 knockout (<i>p21</i> <sup><i>-/-</i></sup> ) and wild-type mice. Bone destruction was analyzed using histology, micro-computed tomography, and bone strength testing; osteoclast formation and activity were evaluated using tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemistry for cathepsin K. The expression of inflammatory cytokines and osteoclast-related genes was examined using immunohistochemistry and real-time polymerase chain reaction, respectively. <i>p21</i> <sup><i>-</i></sup> <i>/</i> <sup><i>-</i></sup> mice exhibited greater bone destruction and lower bone strength than wild-type mice. Additionally, TRAP and cathepsin K staining revealed significantly higher osteoclast count in <i>p21</i> <sup><i>-</i></sup> <i>/</i> <sup><i>-</i></sup> mice. Interleukin (IL)-6, IL-1β, tumor necrosis factor-alpha (TNF-α), and phosphorylated signal transducer and activator of transcription 3 (STAT3) levels were considerably higher in bone tissues of <i>p21</i> <sup><i>-</i></sup> <i>/</i> <sup><i>-</i></sup> mice than in those of wild-type mice. In vitro osteoclast differentiation in bone marrow macrophages (BMMs) was examined after IL-6 stimulation; osteoclast differentiation and osteoclast marker gene expression were significantly enhanced in <i>p21</i> <sup><i>-/-</i></sup> BMMs. Western blotting confirmed increased STAT3 phosphorylation in <i>p21</i> <sup><i>-/-</i></sup> BMMs; IL-6 treatment further amplified osteoclastogenesis in <i>p21</i> <sup><i>-/-</i></sup> BMMs. In conclusion, p21 deficiency exacerbates bone destruction in arthritis by promoting osteoclast differentiation and inflammatory cytokine expression via the IL-6/STAT3 pathway. Targeting p21 may offer therapeutic potential for preventing arthritis-related bone loss, such as in RA.