Down-regulation of miR-193a-3p promotes osteoblast differentiation through up-regulation of LGR4/ATF4 signaling

Emerging evidence indicates that microRNAs (miRNAs) are crucial regulators of osteoblast differentiation. A previous study has reported that miR-193a-3p expression is altered during the induction of osteoblast differentiation. However, the precise biological function and regulatory mechanism of miR193a-3p during osteoblast differentiation remains unclear. In this study, we aimed to investigate the precise role and underlying mechanism of miR-193a-3p in regulating osteoblast differentiation. The results showed that miR-193a-3p expression was significantly down-regulated during the induction of osteoblast differentiation. Functional experiments demonstrated that the overexpression of miR-193a-3p impeded osteoblast differentiation while miR-193a-3p inhibition promoted osteoblast differentiation. Bioinformatics analysis and a luciferase assay revealed that leucine-rich repeat-containing G-protein coupled receptor 4 (LGR4), a critical regulator of osteoblast differentiation, was a target gene of miR-193a-3p. We showed that miR-193a-3p negatively regulated the expression of LGR4 and activating transcription factor 4 (ATF4). Moreover, the knockdown of LGR4 or ATF4 significantly reversed the promotion effect of miR-193a-3p inhibition on osteoblast differentiation. Overall, these findings demonstrate that miR-193a-3p regulates osteoblast differentiation by modulating LGR4/ATF4 signaling and suggests that the miR-193a-3p/LGR4/ATF4 regulation axis may play an important role in regulating bone remodeling. (C) 2018 Elsevier Inc. All rights reserved.