Interleukin-1?-mediated suppression of microRNA-27a-3p activity in human cartilage via MAPK and NF-?B pathways: A potential mechanism of osteoarthritis pathogenesis

Abstract

The aim of the present study was to investigate the role of microRNA (miR)-27a-3p in osteoarthritis (OA). Reverse transcription-quantitative polymerase chain reaction and western blotting were performed to determine the expression of miR-27a-3p and aggrecanase-2 (ADAMTS5) in cartilage tissues from patients with OA and healthy controls, and also in interleukin (IL)-1?-treated primary human chondrocytes. Primary human chondrocytes were transfected with miR-27a-3p. A luciferase reporter assay was used to validate the direct contact between miR-27a-3p and its putative binding site in the 3'-untranslated region ADAMTS5 mRNA. Furthermore, the effects of IL-1?-induced activation of mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-?B on miR-27a-3p were evaluated using specific inhibitors. The results revealed that the level of miR-27a-3p was reduced in OA cartilage tissues compared with those of normal controls. In addition, decreased miR-27a-3p and increased ADAMTS5 expression was observed in a time- and dose-dependent manner in chondrocytes treated with IL-1?. Furthermore, overexpression of miR-27a-3p suppressed the expression of ADAMTS5 in human chondrocytes induced by IL-1?. miR-27a-3p overexpression also decreased the luciferase activity of the wild-type ADAMTS5 reporter plasmid. Mutation of the miR-27a-3p binding site in the 3'-untranslated region of ADAMTS5 mRNA abolished the miR-27a-3p-mediated repression of reporter activity. Furthermore, the use of specific inhibitors demonstrated that IL-1? may regulate miR-27a-3p expression via NF-?B and MAPK signaling pathways in chondrocytes. The present study concluded that miR-27a-3p was downregulated in human OA and was suppressed by IL-1?, and functions as a crucial regulator of ADAMTS5 in OA chondrocytes. In addition, IL-1?-mediated suppression of miR-27a-3p activity may occur via the MAPK and NF-?B pathways. The present study may provide a novel strategy for clinical treatment of OA caused by upregulation of miR-27a-3p.