MicroRNA-17 Suppresses TNF-α Signaling by Interfering with TRAF2 and cIAP2 Association in Rheumatoid Arthritis Synovial Fibroblasts

摘要

TNF-α is a major cytokine implicated in rheumatoid arthritis (RA). TNF-α expression is shown to be regulated at transcriptional as well as posttranscriptional levels. However, the impact of changes in microRNA (miRNA) expression on posttranslational processes involved in TNF-α signaling networks is not well-defined in RA. Here we evaluated the effect of miR-17, a member of miR-17-92~ cluster, on TNF-α signaling pathway in human RA synovial fibroblasts (RASFs). We demonstrated that miR-17 expression was significantly low in RA serum, SFs, and synovial tissues as well as in the serum and joints of adjuvant-induced arthritis rats. RNA sequencing analysis showed modulation of 664 genes by pre-miR-17 in human RASFs. Ingenuity pathway analysis of RNA sequencing data identified the ubiquitin proteasome system (UPS) in TNF-α signaling pathway as a primary target of miR-17. Western blot analysis confirmed the reduction of TRAF2, cIAP1, cIAP2, USP2, and PSMD13 expression by miR-17 in TNF-α-stimulated RASFs. Immunoprecipitation assays showed that miR-17 restoration increased the K48-linked polyubiquitination of TRAF2, cIAP1, and cIAP2 in TNF-α-stimulated RASFs. Thus, destabilization of TRAF2 by miR-17 reduced the ability of TRAF2 to associate with cIAP2, thereby resulting in the downregulation of TNF-α-induced NF-κBp65, c-Jun, and STAT3 nuclear translocation and the production of IL-6, IL-8, MMP-1, and MMP-13 in human RASFs. In conclusion, this study provides evidence for the role of miR-17 as a negative regulator of TNF-α signaling by modulating the protein ubiquitin processes in RASFs.