LncRNA ZFAS1 protects chondrocytes from IL-1ß-induced apoptosis and extracellular matrix degradation via regulating miR-7-5p/FLRT2 axis.

ABSTRACT

BACKGROUND: Increasing evidence suggested that long non-coding RNAs (lncRNAs) played vital roles in osteoarthritis (OA) progression. In this study, we aimed to reveal the protective roles of lncRNA ZFAS1 in osteoarthritis (OA) and further investigated its underlying mechanism. METHODS: The chondrocytes were stimulated by IL-1ß to establish an in vitro OA model. Then, the expression of ZFAS1, miR-7-5p, and FLRT2 in chondrocytes was determined by qRT-PCR. Gain- and loss-of-function assays of ZFAS1, miR-7-5p and FLRT2 were conducted. CCK-8 assay and flow cytometry analysis were performed to detect cell viability and apoptosis rate. The expression levels of cartilage-related proteins, including MMP13, ADAMTS5, Collagen II, and Aggrecan, were measured by western blot analysis. The interaction between ZFAS1 and miR-7-5p, as well as miR-7-5p and FLRT2, was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. RESULTS: The expression of ZFAS1 and FLRT2 was down-regulated, while the expression of miR-7-5p was up-regulated in chondrocytes exposed to IL-1ß. ZFAS1 overexpression promoted cell viability and suppressed apoptosis in IL-1ß-treated chondrocytes. Besides, ZFAS1 overexpression suppressed the expression of MMP13 and ADAMTS5, but promoted the expression of Collagen II and Aggrecan to suppress ECM degradation. The mechanistic study showed that ZFAS1 sponged miR-7-5p to regulate FLRT2 expression. Furthermore, the overexpression of miR-7-5p could neutralize the effect of ZFAS1 in IL-1ß-treated chondrocytes, and suppression of FLRT2 counteracted the miR-7-5p down-regulation role in IL-1ß-treated chondrocytes. CONCLUSIONS: ZFAS1 could promote cell viability of IL-1ß-treated chondrocytes via regulating miR-7-5p/FLRT2 axis. Trial registration Not applicable.