M13, an anthraquinone compound isolated from Morinda officinalis promotes the osteogenic differentiation of MSCs by targeting Wnt/β-catenin signaling

Morinda officinalis (MO) is a herb used in Traditional Chinese Medicine (TCM) for the treatment of osteoporosis. M13, a MO-based anthraquinone compound is known to suppress osteoclast activity. However, whether M13 promotes MSCs osteogenic differentiation and its potential mechanism remains unknown.To examine the influence of M13 on MSCs proliferation and osteogenic differentiation and elucidate the underlying mechanism.The effect of M13 exposure on MSCs proliferation was assessed via CCK8 assay, clone formation assay, immunofluorescence, RT-qPCR, and Western blot. The M13-mediated osteogenesis in vitro and ex vivo were evaluated via ALP and Alizarin red S staining, osteogenesis-associated gene (Runx2, Col1a1 and Opn) expression, and fetal limb explants culture. Molecular docking was employed for target signal pathway screening. The potential signaling mechanisms of M13-promoted MSCs osteogenic differentiation were analyzed by introducing XAV939 (Wnt/β-catenin signaling inhibitor).M13 induced certain obvious positive effects on MSCs proliferation and osteogenic differentiation. Treatment with M13 enhanced MSCs viability and clone numbers. Meanwhile, M13 promoted osteogenic gene expression, enhanced ALP intensity and Alizarin red S staining in MSCs. In terms of mechanism, M13 strongly interacted with the docking site of the WNT signaling complex, thereby activating the Wnt/β-catenin pathway. Furthermore, the M13-mediated osteogenic effect was partially inhibited by XAV939 both in vitro and ex vivo, which confirmed that the Wnt/β-catenin axis is a critical regulator of M13-induced osteogenic differentiation of MSCs.Our study elucidated for the first time that M13 significantly promoted osteogenic differentiation of MSCs via stimulation of the Wnt/β-catenin pathway in vitro and ex vivo.Our findings offered new additional evidence to support the MO or M13-based therapy of osteoporosis.