GIT2 negatively regulates the NF-κB pathway directly or indirectly by regulating TRAF3 expression to promote osteogenic differentiation of BMSCs

BACKGROUND AIMS: Osteoporosis (OP) is a common disease of aging, which is closely related to the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). DNA damage, as a senescence-associated secretory phenotype (SASP), plays an important role in aging diseases including OP. GIT2 has been identified as a DNA repair gene and alleviates aging-related phenotypes. However, the relationship between GIT2 and osteogenic differentiation of BMSCs remains unclear. METHODS: Here, we used bioinformatics analysis to identify the gene GIT2, which is closely related to aging, OP and DNA damage, and its downstream targets. Then, H₂O₂ -induced BMSCs senescence model and ovariectomy-induced mice OP model was established in vitro and in vivo, respectively. Micro-CT, H&E staining, toluidine blue staining, and calcein double labeling were used to analyze bone mass, osteogenic differentiation phenotype, and bone formation rate. Comet assay, Elisa and immunofluorescence were used to analyze senescence-related phenotypes. Western blotting was used to detect the protein levels of GIT2/TRAF3/NF-κB axis and osteogenesis-related markers. RESULTS: Our results showed that GTI2 and TRAF3 were positively correlated with OP-related markers. On the one hand, GIT2 could inhibit the activation of both canonical and non-canonical NF-κB signaling pathways by positively regulating TRAF3. On the other hand, GIT2 could directly bind to P65, a component of the classical NF-κB signaling pathway, and P52, a component of the non-classical NF-κB signaling pathway, to inhibit their activation, improve DNA damage repair, alleviate cell senescence, and further promote osteogenic differentiation of BMSCs. CONCLUSIONS: In summary, the present study demonstrates that GIT2 plays a crucial regulatory role in promoting osteogenic differentiation of BMSCs, which provides new ideas for the prevention and treatment of OP and other aging-related diseases.