Transport of fatty acids across the human placenta: A review

Essential fatty acids and their long chain polyunsaturated fatty acid derivatives (20C) such as docosahexaenoic and arachidonic acids are critical for proper fetal growth and development. Dietary intake as well as metabolism of these fatty acids, and their subsequent transfer from the mother to the fetus are therefore important requisites for developing fetus. The placenta is the key organ through which nutrients such as these fatty acids flow from the mother to the fetus. Cellular uptake and translocation of long chain fatty acids (LCFAs) in different tissues is achieved by a concert of co-existing mechanism. Although LCFA can enter the cell via passive diffusion, emerging reports indicate that LCFA uptake is tightly regulated by several plasma membrane-located transport/binding proteins such as fatty acid translocase (FAT/CD36), plasma membrane fatty acid binding protein (FABPpm), fatty acid transport protein (FATP) and intracellular FABPs in several tissues including human placenta. Fatty acid activated transcription factors (PPARs, LXR, RXR, and SREBP-1) have been demonstrated to regulate these fatty acid transport/binding proteins, and placental functions. Maternal fatty acids therefore may regulate their own placental transport as well as placental function via several fatty acid-activated transcription factors. This review summarizes recent developments on placental fatty acid transport and metabolisms, and the regulatory roles of these proteins in these processes.