Inhibition of miR-665 alleviates lipopolysaccharide-induced inflammation via up-regulation of SOCS7 in chondrogenic ATDC5 cells
Purpose: To examine the effect and mechanism of action of miR-665 in osteoarthritis.
Methods: An in vitro inflammatory injury model of osteoarthritis was established using chondrogenic ATDC5 cells with lipopolysaccharide (LPS) treatment. The expression levels of inflammatory cytokines were determined by enzyme-linked immunosorbent assays (ELISAs) and by quantitative real-time polymerase chain reaction (qRT-PCR). A binding target for miR-665 was predicted using TargetScan and then evaluated using a dual-luciferase reporter assay.
Results: Treatment with LPS significantly up-regulated the inflammatory cytokine expressions of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α), in ATDC5 cells (p < 0.01), and the expression of miRNA-665 was significantly increased in LPS-treated ATDC5 cells (p < 0.01).
Knockdown of miR-665 down-regulated the expression levels of these inflammatory cytokines. Suppressor of cytokine signaling 7 (SOCS7) was identified as a target of miR-665. Data from qRT-PCR and western-blot analyses indicated that SOCS7 expression was promoted by miR-665 inhibition and inhibited by miR-665 over-expression. LPS treatment significantly decreased the expression of SOCS7 protein in ATDC5 cells (p < 0.01), and over-expression of SOCS7 attenuated the LPS-stimulated inflammatory injury. In addition, over-expression of miR-655 enhanced the inflammatory injury and reversed the protective effect of SOCS7 against LPS-stimulated inflammation.
Conclusion: Inhibition of miR-665 alleviated LPS-stimulated inflammatory injury in ATDC5 cells via the up-regulation of SOCS7, suggesting a potential therapeutic target for osteoarthritis.
Keywords: MiR-665, Lipopolysaccharide, Inflammation, SOCS7, Chondrogenic, ATDC5
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