FOXO1-suppressed miR-424 regulates the proliferation and osteogenic differentiation of MSCs by targeting FGF2 under oxidative stress

Liangping Li,Manman Gao,Maik Stiehler,Zhiyu Zhou,Qihua Qi,Xuenong Zou,Jiaquan Luo,Zemin Ling,Sheng Huang

doi:10.1038/srep42331

Abstract

Recently, microRNAs (miRNAs) have been identified as key regulators of the proliferation and differentiation of mesenchymal stem cells (MSCs). Our previous in vivo study and other in vitro studies using miRNA microarrays suggest that miR-424 is involved in the regulation of bone formation. However, the role and mechanism of miR-424 in bone formation still remain unknown. Here, we identified that the downregulation of miR-424 mediates bone formation under oxidative stress, and we explored its underlying mechanism. Our results showed that miR-424 was significantly downregulated in an anterior lumbar interbody fusion model of pigs and in a cell model of oxidative stress induced by H2O2. The overexpression of miR-424 inhibited proliferation and osteogenic differentiation shown by a decrease in alkaline phosphatase (ALP) activity, mineralization and osteogenic markers, including RUNX2 and ALP, whereas the knockdown of miR-424 led to the opposite results. Moreover, miR-424 exerts its effects by targeting FGF2. Furthermore, we found that FOXO1 suppressed miR-424 expression and bound to its promoter region. FOXO1 enhanced proliferation and osteogenic differentiation in part through the miR-424/FGF2 pathway. These results indicated that FOXO1-suppressed miR-424 regulates both the proliferation and osteogenic differentiation of MSCs via targeting FGF2, suggesting that miR-424 might be a potential novel therapeutic strategy for promoting bone formation.

Highlights

Evidence demonstrates that miR-424 is downregulated by oxidative stress in patients and mice after ischaemic stroke[8,9]
To evaluate the status of oxidative stress at different stages in human adipose derived mesenchymal stem cells (hASCs) treated with H2O2, intracellular reactive oxygen species (ROS) was measured by flow cytometry
At 24 h, no significant increase was observed (Fig. 1c). These results suggest that hASCs initially undergo oxidative stress and subsequently maintain redox homeostasis upon exposure to 80 μM H2O2

Summary

Introduction

Evidence demonstrates that miR-424 is downregulated by oxidative stress in patients and mice after ischaemic stroke[8,9]. MiR-424, FOXOs and FGF2 are all associated with bone formation, whether there is a regulatory relationship among these factors during bone formation under oxidative stress has not been defined. Our present work aimed at elucidating the effect of miR-424 on bone formation and the upstream and downstream regulatory mechanisms under oxidative stress. We identified that miR-424, which is repressed transcriptionally by FOXO1, regulates the proliferation and osteogenic differentiation of MSCs by targeting FGF2 under oxidative stress. Our results provide insight into the mechanism of bone formation after implantation and the relationship of FOXO1, miR-424, and FGF2 under oxidative stress

Methods

Results

Discussion

Conclusion