Hypoxia-induced miR-191-C/EBP\u03b2 signaling regulates cell proliferation and apoptosis of fibroblast-like synoviocytes from patients with rheumatoid arthritis

Shanshan Yu,Ming Zong,Ying Lu,Lieying Fan,Qi Tan

doi:10.1186/s13075-019-1861-7

Abstract

BackgroundHypoxia plays an important role in the proliferation of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS), leading to pathology of RA. This study was conducted to evaluate hypoxia-induced microRNAs (hypoxamiR) in RA-FLS and its role in the function of RA-FLS.MethodsRA-FLS were cultured under normoxia (21% O2) or hypoxia (3% O2) condition, followed by a microRNA (miRNA) array analysis. The upregulation of miR-191 by hypoxia was confirmed in RA-FLS and FLS from osteoarthritis (OA) patients by quantitative real-time polymerase chain reaction (RT-PCR). Transfection of miR-191 mimic and inhibitor was used to investigate the function of miR-191 in RA-FLS. The functional targets of miR-191 were predicted by bioinfomatics and then validated by reporter gene assay.ResultsA subset of miRNAs was identified to be induced by hypoxia including miR-191. The upregulation of miR-191 was found to be specific in hypoxic RA-FLS, compared to hypoxic OA-FLS. We observed that miR-191 in RA-FLS increased cellular proliferation via promoting G1/S transition of the cell cycle and suppressed cell apoptosis induced by cell starvation. Bioinformatical analysis and experimental assays identified CCAAT/enhancer binding protein β (C/EBPβ) as a target gene of miR-191 in RA-FLS. Enforced expression of C/EBPβ rescued the cellular phenotypes induced by miR-191. In addition, an inverse correlation between the C/EBPβ level and hypoxia stimulation was found in RA-FLS, and overexpression of C/EBPβ could partly rescue the hypoxia-induced cell proliferation.ConclusionWe demonstrated the miR-191-C/EBPβ signaling pathway mediating the hypoxia-induced cell proliferation in RA.

Highlights

Hypoxia plays an important role in the proliferation of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS), leading to pathology of Rheumatoid arthritis (RA)
In order to determine the potential role of hypoxia-induced microRNAs in RA-FLS, primary RA-FLS from three patients were isolated and cultured under normal or 3% O2 of hypoxia for 24 h
The expression of miR-191 and miR-770 was found to be upregulated in RA-FLS, whereas other three miRNAs showed upregulation by hypoxia treatment in both RA-FLS and OA-FLS (Fig. 1c)

Summary

Introduction

Hypoxia plays an important role in the proliferation of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS), leading to pathology of RA. Rheumatoid arthritis (RA) is a systemic autoimmune disease, which is characterized by chronic joint inflammation and synovial hyperplasia. Rheumatoid arthritis fibroblast-like synoviocytes (FLS), as the main stromal cell population in the joint synovium, proliferate and. Joint damage and fibroblast-like synoviocytes proliferation are all more severe in RA than that in OA, OA has been frequently used as control to study the pathobiology of RA. Reduced oxygen and induced inflammation in the synovium of arthritis have been well demonstrated as the key role in the progression of RA [9]. Our previous study demonstrated that hypoxia promoted cellular proliferation of RA-FLS and angiogenesis in RA though upregulating glucose-6-phosphate isomerase (G6PI) [13]

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Conclusion