METTL3 involves the progression of osteoarthritis probably by affecting ECM degradation and regulating the inflammatory response

We aimed to identify RNA N6-methyladenosine methylation associated genes in osteoarthritis (OA), and to explore possible regulatory mechanisms of these RNA methylation associated genes. Bioinformatics analyses, including differential expression analysis, functional enrichment analysis, verification analysis, and box plot analysis, were conducted based on different datasets from OA and non-OA patients. Gene expression at mRNA and protein levels was determined by quantitative reverse transcription PCR, western blot and immunofluorescence. Interleukin 1 beta (IL-1 beta)-treated SW1353 cells was used as cell model. Lentiviral vector was used for overexpression METTL3 in vitro. CCK-8 assay kit was used to determine cell viability and inflammatory cytokines (IL1 alpha, IL-6, IL-8, IL-10 and TNF-alpha) was detected using ELISA kits. Bioinformatics analysis showed that METTL3 expression was decreased in OA group, which was confirmed in clinical samples. Expression of METTL3 was also reduced in IL-1 beta-treated cells. Levels of inflammatory cytokines were obviously reduced in the METTL3 overexpression group, while IL-1 beta treatment reversed such decrease caused by METTL3 overexpression (p < 0.05). Both METTL3 overexpression and IL-1 beta treatment promoted expression of p65 protein and p-ERK (p < 0.01). Additionally, increased expression of MMP1 and MMP3, and decreased expression of MMP13, TIMP-1, and TIMP2 at both mRNA and protein levels were observed in the METTL3 overexpression group when compared with the control group (p < 0.01). Expression of m6A methylation gene METTL3 was reduced in OA. METTL3 is involved in OA probably by regulating the inflammatory response. METTL3 overexpression may affect extracellular matrix degradation in OA by adjusting the balance between TIMPs and MMPs.

Automated summary

The study identified decreased expression of the m6A methylation gene METTL3 in osteoarthritis, suggesting its involvement in regulating the inflammatory response in OA. Overexpression of METTL3 may impact extracellular matrix degradation in OA through modulation of the balance between TIMPs and MMPs.