EFFECTS OF FATTY-ACIDS ON APOLIPOPROTEIN-B SECRETION BY MCARDLE RH-7777 RAT HEPATOMA-CELLS

The effect of oleic acid (OA), stearic acid (SA) and elaidic acid (EA) on cellular and secreted apolipoprotein (apo) B was examined in McArd le RH-7777 (McArdle) hepatoma cells and in primary rat hepatocytes. Ap oB secretion by McArdle cells was significantly inhibited by 20% in 8 h incubations in medium containing EA and SA and by 50% in medium cont aining OA. In contrast, apoB secretion and cellular apoB of primary ra t hepatocytes was relatively unaffected by incubations in medium conta ining fatty acids. Both B100 and B48 secretion in McArdle wild type an d B48 in apoB mRNA editing enzyme catalytic polypeptide transfectants expressing B48 were inhibited to a similar extent indicating an effect of OA on both apoB species. The effect of OA occurred without changes in cellular apoB or in apoB mRNA abundance suggesting a post-transcri ptional mechanism. Time course studies indicate that the suppressive e ffect of OA requires 4 h of incubation suggesting the depletion of a l imiting factor important in apoB secretion. By increasing the proporti on of palmitic acid to OA in the medium, apoB secretion by McArdle cel ls was progressively restored to control levels implicating an unique role for newly synthesized saturated fatty acid. (C) 1997 Elsevier Sci ence B.V.