The ERα/KDM6B regulatory axis modulates osteogenic differentiation in human mesenchymal stem cells

Osteoporosis is a highly prevalent public health burden associated with an increased risk of bone fracture, particularly in aging women. Estrogen, an important medicinal component for the preventative and therapeutic treatment of postmenopausal osteoporosis, induces osteogenesis by activating the estrogen receptor signaling pathway and upregulating the expression of osteogenic genes, such as bone morphogenetic proteins (BMPs). The epigenetic regulation of estrogen-mediated osteogenesis, however, is still unclear. In this report, we found that estrogen significantly induced the expression of lysine-specific demethylase 6B (KDM6B) and that KDM6B depletion by shRNAs led to a significant reduction in the osteogenic potential of DMSCs. Mechanistically, upon estrogen stimulation, estrogen receptor-α (ERα) was recruited to the KDM6B promoter, directly enhancing KDM6B expression. Subsequently, KDM6B was recruited to the BMP2 and HOXC6 promoters, resulting in the removal of H3K27me3 marks and activating the transcription of BMP2 and HOXC6, the master genes of osteogenic differentiation. Furthermore, we found that estrogen enhanced DMSC osteogenesis during calvarial bone regeneration and that estrogen's pro-osteogenic effect was dependent on KDM6B in vivo. Taken together, our results demonstrate the vital role of the ERα/KDM6B regulatory axis in the epigenetic regulation of the estrogen-dependent osteogenic response.