Bmal1- and Per2-mediated Regulation of the Osteogenic Differentiation and Proliferation of Mouse BMSCs by Modulating the Wnt/β-catenin Pathway

Abstract Bmal1 and Per2 are the core components of the circadian clock genes(CCGs). Bmal1−/− mice exhibited premature aging characterized by osteoporosis and reduced proliferation ability. The same thing occurred in Per2−/− mice, albeit to a less severe degree. However, whether the effects of Bmal1 and Per2 on proliferation and osteogenic differentiation are synergistic or antagonistic remains unclear. To figure this out, we constructed lentiviral and adenoviral vectors to silence or overexpress Bmal1 or Per2 in bone marrow mesenchymal stem cells (BMSCs), and applied MTT, flow cytometry, RT-qPCR, WB, and ChIP-Seq analyses to identify the underlying mechanism. The results showed Bmal1 and Per2 had synergistic effects on the proliferation and differentiation of BMSCs. Furthermore, Bmal1 and Per2 inhibited the Wnt/β-catenin signaling pathway, accompanied by downregulating Rorα expression and upregulating Rev-erbα expression, both of which were also key elements of CCGs. This may be the mechanism by which Bmal1 and Per2 negatively regulate the osteogenic differentiation of BMSCs.