Fatty acid transport regulatory proteins in the developing rat placenta and in trophoblast cell culture models

The placenta forms a selective barrier that is able to transport nutrients that are of critical use to the fetus. Delivery of essential fatty acids to the fetus is dependent upon transplacental transport and provides the back bone for the biosynthesis of biological membranes, myelin and various signa lling molecules. The primary objective of this research was to elucidate th e expression patterns of genes that regulate fatty acid transport across th e placenta. Several fatty acid transport regulatory genes have been identif ied in the rat including; cytoplasmic heart fatty acid binding protein (hFA BP), plasma membrane fatty acid binding protein (FABPpm), fatty acid transl ocase (FAT) and fatty acid transport protein (FATP). In this study, we have elucidated temporal and spatial expression patterns for these genes in the rat placenta and in cell culture models of the rat placenta by Northern bl ot, RT-PCR, Western blot and/or by in situ hybridization analyses. Expressi on of hFABP was specific to the labyrinth zone, the main barrier and site o f transplacental transport in the rat placenta. In addition, the levels of hFABP expression increased with gestational age, suggesting a growing requi rement for fatty acid transport with advancing stages of pregnancy. FABPpm, FAT and FATP are expressed in both the junctional and labyrinth zones of t he rat placenta. FAT was predominantly localized to the labyrinth zone by i n situ hybridization analysis. The placental cell expression patterns of th e genes involved in fatty acid transport were supported by our observations of HRP-1 (labyrinth zone) and Rcho-1 (junctional zone) trophoblast cell cu lture models. Given their cell surface location, we predict that FABPpm, FA T and FATP potentially participate in placental fatty acid uptake. The pred ominant expression of hFABP and FAT in the labyrinth zone of the chorioalla ntoic placenta implicates hFABP and FAT in the transplacental movement of f atty acids from maternal to fetal compartments. (C) 2000 Harcourt Publisher s Ltd.