Long noncoding RNA XIST regulates osteogenic differentiation of human bone marrow mesenchymal stem cells by targeting miR-9-5p.

This study aimed to investigate whether X inactivate-specific transcript (XIST) regulated the expression of tissue non-specific alkaline phosphatase (ALPL) through miR-9-5p to promote osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs). We elucidated the molecular regulation mechanisms of XIST underlying osteogenic differentiation of hBMSCs. In osteoporotic patients with hBMSCs, the expression of miR-9-5p was upregulated and the expression of XIST was downregulated. When hBMSCs were treated with osteogenic induction, the expression of XIST was increased and the expression of miR-9-5p was decreased. The osteogenic differentiation of hBMSCs was significantly decreased after knocking down XIST. Luciferase analysis revealed that XIST could directly bind to miR-9-5p and exert a negative regulatory effect on its expression. MiR-9-5p could bind directly to the 3'-UTR of ALPL and inhibit the expression of ALPL. Knockout of XIST reduced the expression of ALPL, while co-transfection of the miR-9-5p inhibitor could reverse the expression of the ALPL gene. In hBMSCs, overexpression of XIST upregulated the expression of ALPL, but the miR-9-5p mimic could reverse the expression of ALPL. Furthermore, silencing of ALPL could downregulate the expression of osteopontin(OPN) and osteocalcin(OCN) induced by miR-9-5p inhibitors. In conclusion, XIST regulated the expression of ALPL by targeting miR-9-5p. It could be used as a positive regulator of osteogenic differentiation of hBMSC.