Mettl14 KO and WT mouse single cell RNA sequencing

Without intervention, a considerable proportion of metabolic fatty liver disease (MAFLD) patients will progress from simple steatosis to metabolic steatohepatitis, liver fibrosis and even hepatocellular carcinoma. However, the molecular mechanisms that control progressive MAFLD have yet to be fully determined. Here, the N6-methyladenosine (m6A) methyltransferase METTL14 hepatocyte conditional knockout mouse model was created. In vivo and in vitro experiments were performed to identify the mechanism of MAFLD progression caused by low METTL14 expression in hepatocytes. In details, METTL14 downregulation decreased GLS2 by affecting the translation efficiency mediated by YTHDF1 in a m6A-depedent manner, which might help to form an oxidative stress microenvironment. Considering that the oxidative stress microenvironment of liver tissue is the basic feature of MAFLD-related liver tissue and the key factor in fostering the progression of inflammation, non-parenchymal cells of one KO and one WT mouse liver were used for single cell RNA sequencing (scRNA-seq). It was further revealed that METTL14/GLS2 downregulation recruited Cx3cr1+Ccr2+ monocyte-derived macrophages (Mo-macs). Further experiments revealed that CX3CR1 can activate the transcription of S100A4 via CX3CR1/MyD88/NF-κB signaling pathway in Cx3cr1+Ccr2+ Mo-macs. Restoration of METTL14 or GLS2, or blocking the above pathway such as inhibiting MyD88 could ameliorate liver injuries and fibrosis. Taken together, these findings indicate potential therapies for the treatment of MAFLD progression.