GIT2 negatively regulates the NF-κB pathway directly or indirectly by regulating TRAF3 expression to promote...

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.

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.

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.

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.