Circ-Plod2 destabilizes Mpo mRNA by binding to IGF2BP2 to promote osteogenic differentiation of bone marrow mesenchymal stem cells

Osteogenic differentiation, proliferation, and/or apoptosis of bone marrow mesenchymal stem cells (BMSCs) are involved in the progression of postmenopausal osteoporosis (PMO). However, circular RNA (circRNA)-mediated changes in the cellular function of BMSCs in PMO are still unclear. This study revealed the excellent ability of circ-Plod2 to promote osteogenic differentiation of BMSCs and its molecular mechanisms. In this study, ovariectomized (OVX) rats and control (Sham) rats were used to simulate PMO. Initially, we found that the expression of circ-Plod2 in OVX BMSCs is down-regulated and the expression of the Mpo gene is up-regulated by sequencing and verification. Further, we confirmed that circ-Plod2 is located in the cytoplasm and belongs to exon-type circRNA. Interestingly, circ-Plod2 promotes Mpo-dependent osteogenic differentiation of BMSCs without affecting proliferation, apoptosis, adipogenic differentiation, or chondrogenic differentiation of BMSCs. Mechanistically, we demonstrated that circ-Plod2 specifically binds IGF2BP2 to form an RNA-protein complex that destabilizes Mpo mRNA. Overexpression of circ-Plod2 in the bone marrow cavity effectively alleviated osteoporosis in OVX rats and inhibited the expression of MPO in BMSCs. Together, this study reveals that circ-Plod2 destabilizes Mpo mRNA by binding to IGF2BP2 to promote osteogenic differentiation of BMSCs to alleviate osteoporosis. The findings of this study may provide biomarkers for the diagnosis of PMO, and may also provide potential strategies for the clinical treatment of PMO.