RESUMEN
Long noncoding RNAs (lncRNAs) have been considered as important modulators in the development of osteoarthritis. The present study investigates whether there is a link between lncRNA small nucleolar RNA host gene 5 (SNHG5) and osteoarthritis pathogenesis, and the underlying molecular mechanism. To establish an in vitro model of osteoarthritis, interleukin 1ß (IL-1ß) was used to treat chondrocytes (C20/A4 cells) for mimicking the inflammatory condition in osteoarthritis pathogenesis. SNHG5 and miR-181a-5p expression levels were then detected in cartilage tissues of osteoarthritis patients and C20/A4 cells by quantitative polymerase chain reaction (qPCR). Cell counting kit-8 and 5-ethynyl-2'-deoxyuridine assays were applied for detecting the viability of chondrocytes, and the apoptosis of chondrocytes was examined through caspase-3 activity assay and flow cytometry analysis. Western blot and qPCR were employed for determining the expression levels of TGFBR3, ADAMTS5, and MMP-13. The regulatory relationships among SNHG5, miR-181a-5p, and TGFBR3 were verified by RNA immunoprecipitation and dual-luciferase reporter assays. The expression levels of SNHG5 and TGFBR3 were markedly decreased, and miR-181a-5p expression was enhanced in osteoarthritis tissues and chondrocytes treated with IL-1ß. SNHG5 knockdown inhibited the viability of chondrocytes, induced apoptosis, and promoted the expression levels of ADAMTS5 and MMP-13. Conversely, SNHG5 overexpression could counteract the effects of IL-1ß, increase the viability of chondrocytes and suppress apoptosis. Mechanically, SNHG5 positively regulated TGFBR3 expression via sponging miR-181a-5p. Moreover, miR-181a-5p overexpression and TGFBR3 knockdown counteracted the effects of SNHG5 on chondrocytes. SNHG5 can probably protect chondrocytes from the inflammatory response and reduce the degradation of the extracellular matrix via modulating the miR-181a-5p/TGFBR3 axis.