USP2-induced upregulation of LEF1 through deubiquitination relieves osteoporosis development by promoting the osteogenic differentiation of bone marrow mesenchymal stem cells

Background: Bone marrow mesenchymal stem cells (BMSCs) exhibit therapeutic potential for osteoporosis through their differentiation into osteoblasts. Here, we investigated the role and mechanism of lymphoid enhancer-binding factor 1 (LEF1) in regulating osteogenic differentiation of human BMSCs (hBMSCs).

Methods: hBMSCs were exposed to the specific medium to induce their osteogenic differentiation. The ovariectomy (OVX)-induced osteoporotic mouse model was constructed. LEF1 and USP2 mRNA expression was analyzed by quantitative PCR, and protein levels were detected by immunohistochemistry and immunoblotting. Cell proliferation was assessed by CCK-8 assay. Alkaline Phosphatase (ALP) expression and activity assay and Alizarin Red staining were used to evaluate osteogenic differentiation. LEF1 protein stability analysis and co-immunoprecipitation (Co-IP) assay were performed to test the USP2/LEF1 interaction.

Results: During hBMSC osteogenic differentiation, LEF1 and USP2 levels were increased in hBMSCs. Inhibiting LEF1 or USP2 diminished the proliferation and osteogenic differentiation of hBMSCs in vitro. Mechanistically, USP2 stabilized LEF1 protein by mediating LEF1 deubiquitination. Increased expression of LEF1 reversed USP2 knockdown-imposed suppression on proliferation and osteogenic differentiation of hBMSCs. Moreover, increased USP2 expression reduced bone loss and enhanced osteogenic differentiation in OVX mice. Additionally, LEF1 and USP2 were downregulated in the bone marrow of patients with osteoporosis.

Conclusion: Our findings provide the first demonstration of the USP2/LEF1 cascade that enhances the osteogenic differentiation of hBMSCs, broadening the field for the development of BMSCs as effective agents in osteoporosis therapy.

LEF1; Osteogenic differentiation; Osteoporosis; USP2; hBMSCs.