Investigation of controlled human extravillous trophoblast invasion

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Human trophoblasts differentiate into two main cell lineages : villous and extravillous cells. Villous trophoblasts cover the chorionic villi of the placenta, their function being to transport oxygen and nutrients from the mother to the fetus. In contrast, extravillous trophoblasts (EVT) invade maternal uterus and also migrate up the spiral arteries, transforming them into large vessels of low resistance. Many aspects of EVT invasion are similar to events that occur during tumor cell invasion. However, unlike tumor invasion, EVT invasion is precisely regulated, confined spatially to the uterus and temporally to early pregnancy. The mechanism of controlled EVT invasion is not clarified well.Therefore in this project, we first identified molecules which specifically express in EVT by several methods. Thereafter, we examined the role of each molecule in human trophoblasts, especially in their controlled invasiveness.We raised mouse mAb against human term chorion laeve (its contains abunda … More nt EVT) to identify novel molecules which are expressed in EVT.Several mAb clones which react with EVT were obtained, and their antigens were analyzed by amino acid sequencing, cDNA panning, or by immunoscreening method. These analyses revealed that integrin alpha 5, cytokeratin 18, and melanoma cell adhesion molecule (MCAM) are expressed in EVT.In addition, mAb 5-23 recognized the unknown cell surface protein of 200 kD.Besides mAb analyses, we carried out cDNA microarray analysis to identify genes which is differently expressed in non-invasive EVT of 3rd trimester chorion laeve compared with still invasive EVT of 1st trimester placenta. Several expressed sequence tag (EST) of unknown function were identified. Among these EST, EST9 was predominantly expressed in 1st trimester placenta which contains invasive EVT.Full length cDNA was determined by 5'RACE, and resultant EST9 mRNA of 6kb encoded a putative transcription factor of 40kD protein. Functions of EST9 in human trophoblast are now under investigation. Less