<scp>ACSL1</scp> Contributes to Metabolic‐Associated Fatty Liver Disease by Mediating Arachidonic Acid Metabolism

The precise involvement of ACSL1 in metabolic-associated fatty liver disease (MAFLD) pathogenesis remains unclear. To this end, we analyzed the effects of long-chain acyl-CoA synthase (ACSL1) on MAFLD. Analysis of GEO datasets showed that ACSL1 was downregulated in MAFLD. To elucidate its mechanistic role, we generated BRL hepatocyte cell lines with stable ACSL1 knockdown or overexpression. These engineered cells were cultured with a lipid mixture containing 300 μM oleic acid, 150 μM palmitic acid, and 100 μM linoleic acid (OPL) to mimic MAFLD pathophysiology in vitro. Lipidomic profiling identified 195 upregulated and 357 downregulated lipid metabolites in OPL-treated ACSL1-knockdown cells (OPL-shACSL1). Notably, the OPL-shACSL1 group exhibited marked elevations in free fatty acids, including linoleic acid, arachidonic acid (AA), FA20:3, FA22:5, and FA22:2, accompanied by enhanced AA metabolism. Western blotting demonstrated that ACSL1 knockdown significantly upregulated key enzymes in AA metabolic pathways, including ELOVL5, COX1, and LOX5. Consistent with these in vitro findings, mice with high-fat diet-induced MAFLD showed reduced hepatic ACSL1 expression with concurrent elevation of COX1 protein levels. Co-immunoprecipitation assays showed that ACSL1 did not interact with LOX5 or COX1. Our findings demonstrate that ACSL1 knockdown enhances AA metabolism, evidenced by elevated levels of AA-related metabolites and upregulated expression of key enzymes (ELOVL5, COX1, LOX5), and suggest that ACSL1 may represent a potential therapeutic target for MAFLD.