ETV4 promotes lipid accumulation and oxidative stress in metabolic dysfunction-associated fatty liver disease by transcriptionally activating TYMS

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic liver disorder, with non-alcoholic steatohepatitis (NASH) as its progressive stage. This study aimed to identify diagnostic biomarkers and investigate the mechanism by which ETS variant transcription factor 4 (ETV4) regulated MAFLD via thymidylate synthase (TYMS). Gene expression profiles from GSE126848 and GSE89632 were analyzed to identify differentially expressed genes using |log2FC| > 1.5 and adjusted P < 0.05, followed by intersection analysis. Machine learning algorithms were applied to identify key genes. A NASH-like model was established in Huh-7 cells using palmitic acid (PA) and oleic acid (OA). Gene expression was measured by RNA extraction and real-time quantitative polymerase chain reaction and Western blot. Cell viability, lipid accumulation, triglyceride and total cholesterol levels, malondialdehyde content, and reactive oxygen species levels were assessed by Cell Counting Kit-8, Oil Red O staining, and commercial kits. Dual-luciferase reporter and chromatin immunoprecipitation assays were used to verify ETV4-mediated transcriptional regulation of TYMS. TYMS was identified as a key gene and was significantly upregulated in the PA + OA-induced Huh-7 cell model ( P < 0.05). TYMS knockdown alleviated PA + OA-induced lipid accumulation, inflammatory responses, and oxidative stress in Huh-7 cells ( P < 0.05). ETV4 was upregulated in the cellular model and directly bound to the promoter region of TYMS to transcriptionally activate its expression ( P < 0.05). TYMS overexpression significantly reversed the protective effects induced by ETV4 knockdown ( P < 0.05). ETV4 promoted lipid accumulation and oxidative stress in hepatocytes by transcriptionally activating TYMS, thereby exacerbating the progression of MAFLD. TYMS represents a candidate diagnostic biomarker and potential intervention target for MAFLD.