microRNA‐143‐3p regulates odontogenic differentiation of human dental pulp stem cells through regulation of the osteoprotegerin–RANK ligand pathway by targeting RANK

New Findings What is the central question of this study? What is the role of miR‐143‐3p during human dental pulp stem cell (hDPSC) differentiation. What is the main finding and its importance? miR‐143‐3p negatively regulates receptor activator of nuclear factor‐κB (RANK). RANK ligand (RANKL) binds to RANK and stimulates the development of osteoclasts. Osteoprotegerin (OPG) inhibits the interaction between RANK and RANKL. The OPG–RANKL signalling pathway regulates odontogenic differentiation of hDPSCs. Abstract Human dental pulp stem cells (hDPSCs) are capable of differentiating into odontoblast‐like cells, which secrete reparative dentin after injury, in which the role of microRNA‐143‐3p (miR‐143‐3p) has been identified. Therefore, we investigated the mechanism by which miR‐143‐3p influences odontoblastic differentiation of hDPSCs. The relationship between miR‐143‐3p and receptor activator of nuclear factor‐κB (RANK) was initially identified by bioinformatics prediction and further verified by dual luciferase reporter gene assay. Gain‐ and loss‐of‐function analysis with miR‐143‐3p mimic and miR‐143‐3p inhibitor was subsequently conducted. Dentin sialophosphoprotein (DSPP), bone sialoprotein (BSP), alkaline phosphatase (ALP), osteocalcin (OCN) and osteopontin (OPN) mRNA levels were then evaluated by RT‐qPCR. Osteoprotegerin (OPG), RANK ligand (RANKL), nuclear factor‐κB (NF‐κB) p65 protein levels and the extent of NF‐κB p65 phosphorylation were examined by western blot analysis. Alizarin red staining was performed to assess the mineralization of hDPSCs. Cell apoptosis and cell cycle distribution were determined using flow cytometry. During odontoblastic differentiation of hDPSC, miR‐143‐3p had high expression, but RANK expression was low. miR‐143‐3p was found to target RANK, and its inhibition enhanced mineralization and hDPSC apoptosis, while blocking cell cycle entry. At the same time, miR‐143‐3p inhibition elevated the extent of NF‐κB p65 phosphorylation, as well as the expression of RANK, RANKL, DSPP, BSP, ALP, OCN and OPN, while decreasing the OPG level. Silencing RANK had opposite effects on these markers. miR‐143‐3p regulates odontoblastic differentiation of hDPSCs via the OPG–RANKL pathway that targets RANK. The elucidation of the mechanisms of odontogenic differentiation of hDPSCs may contribute to the development of effective dental pulp repair therapies for the clinical setting.