CircRNA_28313/miR-195a/CSF1 axis modulates osteoclast differentiation to affect OVX-induced bone absorption in mice

Osteoblastic bone formation and osteoclastic bone resorption dynamically maintain the bone homeostasis; in the present study, we attempt to investigate the mechanism of the excessive activation of osteoclasts inducing the deregulation of bone homeostasis from the perspective of non-coding RNA regulation. Differentially expressed patterns of circRNAs were examined in non-treated and RANKL + CSF1-treated bone marrow monocyte/macrophage (BMM) cells and differentially-expressed miRNAs during osteoclast differentiation were analyzed and identified. We found that circRNA_28313 was significantly induced by RANKL + CSF1 treatment. circRNA_28313 knockdown significantly inhibited RANKL + CSF1-induced differentiation of osteoclasts within BMM cells <i>in vitro</i>, while suppressed ovariectomized (OVX)-induced bone resorption in mice <i>in vivo</i>. Via bioinformatics analyses, it has been demonstrated that miR-195a might bind to circRNA_28313 and CSF1 and together form a circRNA-miRNA-mRNA network. circRNA_28313 relieves miR-195a-mediated suppression on CSF1 via acting as a ceRNA, therefore modulating the osteoclast differentiation in BMM cells. In conclusion, circRNA_28313, miR-195a, and CSF1 form a ceRNA network to function in RANKL + CSF1-induced osteoclast differentiation, thus affecting OVX-induced bone absorption in mice.