Overexpression of Acyl-CoA binding protein and its effects on the flux of free fatty acids in McA-RH 7777 cells

Overexpression of acyl-CoA binding protein (ACBP) was induced in a rat hepatoma cell line (McA-RH 7777) by stable integration of rat ACBP cDNA. The transfected cells (ACBP-27) had 3.5-fold higher concentrations of ACBP than control cells (14 vs. 4 ng/mug DNA). Both ACBP-27 and control cells were cultured in the presence of various concentrations of radiolabeled palmitic acid; and the effects of ACBP on lipogenesis and beta -oxidation were studied, Incubation of the cells with 100 muM palmitic acid resulted in 42% greater incorporation of the fatty acid in ACBP-27 cells as compared to that in the control cells. This increased incorporation of the fatty acid was observed predominantly in the triglyceride fraction. Higher concentrations of palmitic acid (200 to 400 muM) were associated with a significant decrease in the production of (CO2)-C-14 in the ACBP-27 cell line than in the control cells, while lower concentrations had no effect. Our data suggest a role for ACBP in the partitioning of fatty acids between esterification reactions leading to the formation of neutral lipids and beta -oxidation. ACBP may play a regulatory role by influencing this important branch point in intermediary lipid metabolism.