TNF-α-induced NF-κB activation upregulates microRNA-150-3p and inhibits osteogenesis of mesenchymal stem cells by targeting β-catenin.

Nan Wang,Chenhao Pan,Wei Liu,Peipei Yin,Xiaowei Yu,Zubin Zhou,Tianyi Wu

doi:10.1098/rsob.150258

Abstract

Although systemic or local inflammation, commonly featured by cytokine activation, is implicated in patients with bone loss, the underlying mechanisms are still elusive. As microRNAs (miR), a class of small non-coding RNAs involved in essential physiological processes, have been found in bone cells, we aimed to investigate the role of miR for modulating osteogenesis in inflammatory milieu using human bone marrow mesenchymal stem cells (hBM-MSCs). Induced by proinflammatory cytokine TNF-α, miR-150-3p was identified as a key player in suppressing osteogenic differentiation through downregulating β-catenin, a transcriptional co-activator promoting bone formation. TNF-α treatment increased the levels of miR-150-3p, which directly targeted the 3′-UTR of β-catenin mRNA and in turn repressed its expression. In addition, we observed that miR-150-3p expression was increased by TNF-α via IKK-dependent NF-κB signalling. There are three putative NF-κB binding sites in the promoter region of miR-150, and we identified −686 region as the major NF-κB binding site for stimulation of miR-150 expression by TNF-α. Finally, the osteogenic differentiation of hBM-MSCs was inhibited by either miR-150-3p overexpression or TNF-α treatment, which was prevented by anti-miR-150-3p oligonucleotides. Taken together, our data suggested that miR-150-3p integrated inflammation signalling and osteogenic differentiation and may contribute to the inhibition effects of inflammation on bone formation, thus expanding the pathophysiological functions of microRNAs in bone diseases.

Highlights

A delicate balance between bone resorption and bone formation is required for maintaining the integrity of human bones and physiological functions of the skeletal system, both of which are often disrupted in inflammatory diseases [1,2,3]
We examined the target genes that are known to be repressed by TNF-a, including peroxisome proliferator-activated receptor alpha (PPAR-a), intercellular adhesion molecule 2 (ICAM2), growth hormone receptor (GHR), CRH receptor-2 (CRH-R2), endothelial nitric oxide synthase and b-catenin [25,26,27,28,29,30]
In hBM-MSCs transfected with miR-150-3p, only b-catenin expression was decreased compared with the miR negative controls, suggesting that miR-150-3p induction by TNF-a might mediate the suppression of b-catenin in hBM-MSCs

Summary

Introduction

A delicate balance between bone resorption and bone formation is required for maintaining the integrity of human bones and physiological functions of the skeletal system, both of which are often disrupted in inflammatory diseases [1,2,3]. TNF-a is a major proinflammatory cytokine that mediates essential functions associated in bone mass regulation [6]. Bone resorption activated by TNF-a has been well characterized [7,8], mediated by the processes such as the increased numbers of osteoclast precursor, enhanced osteoclast differentiation and stimulated osteoclast functional maturation. The inhibition of Wnt/b-catenin signalling may be directly relevant to the suppressive effects of TNF-a or other proinflammatory cytokines on osteogenic differentiation. Cross-regulations between Wnt and TNF-a signalling have been suggested, and the major downstream player NF-kB activated by TNFa may mediate the inhibition of Wnt pathway [10,11,15,16]. The list of molecular players involved in this process is incomplete

Objectives

Methods

Results

Discussion

Conclusion