Mmu_circ_009056 promotes osteogenic differentiation and mineralization of BMSCs via miR-139-3p

Abstract Bone remodeling is a dynamic process involving bone-forming osteoblasts and bone-resorting osteoclasts. Imbalanced bone metastases may alter the structure, mass and overall strength of the bone. Circular RNAs contribute to the osteoblastic differentiation process of stromal cells, however, the roles of which are not fully understood in bone marrow stromal cells (BMSCs). Here we reported the circular RNA mmu_circ_009056 was significantly upregulated in BMSCs undergoing osteoblastic differentiation. Knockdown of mmu_circ_009056 by siRNA decreased the expression of osteogenic genes Runx2 and Alp. Using high-throughput sequencing technique and bioinformatic tools, miR-139-3p was predicted to be a target of mmu_circ_009056, and the expression of miR-139-3p was increased after mmu_circ_009056 silencing. Moreover, inhibition of miR-139-3p increased osteoblastic differentiation of BMSCs, while miR-139-3p overexpression decreased osteoblastic differentiation and the expression of ALP and RUNX2 in BMSCs, as evidenced by Alizarin staining, RT-PCR and western blot. The paired box family member 5 (Pax5) was identified as a target gene using gene binding site prediction tools, and its expression was negatively correlated with miR-139-3p expression. Collectively, our findings demonstrate that mmu_circ_009056 plays as a regulator of miR-139-3p during osteogenic differentiation of BMSCs, and Pax5 is a potential target of miR-139-3p.