UPTAKE OF LONG-CHAIN FATTY-ACIDS BY HUMAN PLACENTAL CHORIOCARCINOMA (BEWO) CELLS - ROLE OF PLASMA-MEMBRANE FATTY-ACID-BINDING PROTEIN

In order to understand the mechanisms by which fatty acids are taken u p by the placenta, the uptake of oleic, linoleic, arachidonic, and doc osahexaenoic acids by cultured human placental choriocarcinoma (BeWo) cells was examined. Fatty acid uptake by BeWo cells was temperature-de pendent and exhibited saturable kinetics. Oleic acid was taken up leas t and docosahexaenoic acid most by these cells. Moreover, competitive studies of fatty acid uptake by BeWo cells also indicated preferential uptake compared with oleic acid in the order of docosahexaenoic acid, arachidonic acid, and linoleic acid. Western blot analysis demonstrat ed that BeWo cells express a protein immunoreactive with antibodies to the human placental plasma membrane fatty acid-binding protein (p-FAB P(pm)). Furthermore, pre-treatment of BeWo cells with these antibodies inhibited most of the uptake of docosahexaenoic (64%) and arachidonic acids (68%) whereas oleic acid uptake was inhibited only 32% compared with the controls treated with preimmune serum. These results clearly demonstrate that the p-FABP(pm) may be involved in the preferential u ptake of essential fatty acids (EFA) and their long chain polyunsatura ted fatty acids (LCPUFA) by these cells. Studies on the distribution o f radiolabeled fatty acids in the cellular lipids of BeWo cells showed that docosahexaenoic acid was incorporated mainly in the triacylglyce rol fraction, followed by the phospholipid fraction, whereas for arach idonic acid the reverse was true. The preferential incorporation of do cosahexaenoic acid into triacylglycerol suggests that triacylglycerol may play an important role in the placental transport of docosahexaeno ic acid to the fetal circulation. Together these results demonstrate t he preferential uptake of EFA/LCPUFA by BeWo cells that is most probab ly mediated via the p-FABP(pm). We thus propose that the p-FABP(pm) ma y be involved in the sequestration of maternal plasma LCPUFA by the pl acenta.