CircRNA hsa_circ_0001421 promotes the osteoblast differentiation of human adipose mesenchymal stem cells through the miR-608/SP7 axis

Human adipose mesenchymal stem cells (hAMSCs) can differentiate into osteoblasts, which can enhance bone mass and bone formation. Circular RNA plays an important role in the osteoblast differentiation of mesenchymal stem cells, but the mechanism remains unclear. We used hAMSCs to study the role of circRNA hsa_circ_0001421/miR-608/SP7 axis in osteoblast differentiation. qRT-PCR, western blotting, alkaline phosphatase (ALP) activity measurement, and alizarin red staining (ARS) were used to evaluate the osteoblast differentiation ability of hAMSCs. Dual luciferase reporter gene assay to analyze the relationship of miR-608 with circRNA hsa_circ_0001421 and SP7. Our results showed that circRNA hsa_circ_0001421 could promote the osteoblast differentiation of hAMSCs. qRT-PCR and western blotting showed that the expression of osteogenic genes (ALP, RUNX2, and OCN) was upregulated, and ALP activity and ARS were significantly increased. The dual luciferase reporter gene assay showed that miR-608 competitively binds with circRNA hsa_circ_0001421 and SP7. MiR-608 inhibited the expression of SP7 and repressed the osteoblast differentiation of hAMSCs, whereas circRNA hsa_circ_0001421 inhibited the expression of miR-608 and reversed the downregulation of SP7 by miR-608. Taken together, the circRNA hsa_circ_0001421/miR-608/SP7 axis at least partially regulates the osteoblast differentiation of hAMSCs, which may be a potential target of hAMSCs for the treatment of osteoporosis.