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 hepa toma cell line (McA-RH 7777) by stable integration of rat ACBP cDNA. The tr ansfected cells (ACBP-27) had 3.5-fold higher concentrations of ACBP than c ontrol cells (14 vs. 4 ng/mug DNA). Both ACBP-27 and control cells were cul tured in the presence of various concentrations of radiolabeled palmitic ac id; and the effects of ACBP on lipogenesis and beta -oxidation were studied , Incubation of the cells with 100 muM palmitic acid resulted in 42% greate r incorporation of the fatty acid in ACBP-27 cells as compared to that in t he control cells. This increased incorporation of the fatty acid was observ ed predominantly in the triglyceride fraction. Higher concentrations of pal mitic 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 c ells, while lower concentrations had no effect. Our data suggest a role for ACBP in the partitioning of fatty acids between esterification reactions l eading to the formation of neutral lipids and beta -oxidation. ACBP may pla y a regulatory role by influencing this important branch point in intermedi ary lipid metabolism.