Role of IGF2BP3 in trophoblast cell invasion and migration.

The insulin-like growth factor-2 mRNA-binding protein 3 (IGF2BP3) is a member of a highly conserved protein family that is expressed specifically in placenta, testis and various cancers, but is hardly detectable in normal adult tissues. IGF2BP3 has important roles in RNA stabilization and translation, especially during early stages of both human and mouse embryogenesis. Placenta is an indispensable organ in mammalian reproduction that connects developing fetus to the uterine wall, and is responsible for nutrient uptake, waste elimination and gas exchange. Fetus development in the maternal uterine cavity depends on the specialized functional trophoblast. Whether IGF2BP3 plays a role in trophoblast differentiation during placental development has never been examined. The data obtained in this study revealed that IGF2BP3 was highly expressed in human placental villi during early pregnancy, especially in cytotrophoblast cells (CTBs) and trophoblast column, but a much lower level of IGF2BP3 was detected in the third trimester placental villi. Furthermore, the expression level of IGF2BP3 in pre-eclamptic (PE) placentas was significantly lower than the gestational age-matched normal placentas. The role of IGF2BP3 in human trophoblast differentiation was shown by in vitro cell invasion and migration assays and an ex vivo explant culture model. Our data support a role of IGF2BP3 in promoting trophoblast invasion and suggest that abnormal expression of IGF2BP3 might be associated with the etiology of PE.