Quercetin alleviates LPS-induced embryonic lung fibroblast injury by regulating METTL3/TBL1XR1 expression

Abstract Background Pneumonia is a serious respiratory disease that significantly impacts human health. Quercetin (QUE), a plant extract, has been shown to exert protective effects against lung injury, but its precise mechanisms remain unclear. Methods Lipopolysaccharide (LPS) was used to induce injury in embryonic lung fibroblasts. Cell viability, proliferation, and apoptosis were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, 5-ethynyl-2’-deoxyuridine (EdU) staining, and flow cytometry assay, respectively. Reactive oxygen species (ROS), malondialdehyde (MDA), and Fe 2+ levels were evaluated using corresponding assay kits. The levels of inflammatory factors were determined by enzyme-linked immunosorbent assay (ELISA). Quantitative real-time PCR (qRT-PCR) and western blot were employed to analyze the expression and correlation of related genes. Methylated RNA immunoprecipitation (MeRIP) was employed to verify the regulatory mechanism between genes. Results QUE inhibited embryonic lung fibroblast injury. Both transducin β-like 1 X-linked receptor 1 (TBL1XR1) and methyltransferase 3 (METTL3) were highly expressed in lung injury tissues and cells, which were decreased by QUE treatment. TBL1XR1 deficiency weakened LPS-induced embryonic lung fibroblast injury. Mechanistically, METTL3 mediated the N 6 -methyladenosine (m6A) methylation and stabilized the TBL1XR1 mRNA. TBL1XR1 up-regulation alleviated the retardation of METTL3 absence on embryonic lung fibroblast injury. Furthermore, METTL3 overexpression reversed the inhibition of QUE on embryonic lung fibroblast injury. Conclusion QUE inhibited embryonic lung fibroblast injury by regulating the METTL3-mediated m6A methylation of TBL1XR1 mRNA.