ABSTRACT
Studies reported the positive and negative osteogenic effects of MEG3 in mesenchymal stem cells (MSCs). This study aims at clarifying the osteogenic potential of MEG3 and the underlying mechanism. Bone morphogenetic protein 9- (BMP9-) transfected MSCs were recruited as an osteogenic model in vitro, and ectopic bone formation were used in vivo to explore the effect of MEG3 on osteogenesis. We found that overexpression of MEG3 facilitated BMP9-induced osteogenic markers, ALP activities, and matrix mineralization. However, knockdown of MEG3 attenuated BMP9-induced osteogenic markers. MEG3 increased the phosphorylation of GSK-3ß and the protein level of ß-catenin. Pyruvate dehydrogenase kinase 4 (PDK4) can also combine with GSK-3ß and increase the latter phosphorylation. Moreover, MEG3 increased the mRNA level of PDK4. The ceRNA analysis showed that MEG3 may regulate the expression of PDK4 via microRNA 532-5p (miR-532-5p). The MEG3-enhanced GSK-3ß/ß-catenin axis can be attenuated by miR-532-5p, and miR-532-5p inhibitor partly rescued endogenous PDK4 and MEG3-mediated expression of PDK4. MEG3 may potentiate PDK4 and GSK-3ß/ß-catenin by inhibiting miR-532-5p.
