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/μg 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 β-oxidation were studied. Incubation of the cells with 100 μM 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 predominanly in the triglyceride fraction. Higher concentrations of palmitic acid (200 to 400 μM) were associated with a significant decrease in the production of ¹⁴CO₂ in the ACBP-27 cell line than in the control cells, while lower concentrations had not 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 β-oxidation. ACBP may play a regulatory role by influencing this important branch point in intermediary lipid metabolism. [ABSTRACT FROM AUTHOR]