During blastocyst implantation, interaction between integrins on the apical surface of the trophoblast and extracellular matrix (ECM) in the endometrium anchors the embryo to the uterine wall. Strong adhesion of the blastocyst to fibronectin (FN) requires integrin signaling initiated by exogenous fibronectin. However, it is not known how integrin signaling enhances blastocyst adhesion. We present new evidence that the integrin, αIIbβ3, plays a key role in trophoblast adhesion to fibronectin during mouse peri-implantation development. Trafficking of αIIb to the apical surface of the trophoblast increased dramatically after blastocysts were exposed to fibronectin, whereas other fibronectin-binding integrins, α5β1 and αVβ3, were resident at the apical surface before ligand exposure. Functional comparisons among the three integrins revealed that ligation of α5β1 most efficiently strengthened blastocyst fibronectin-binding activity, while subsequent trophoblast cell migration was dependent primarily on the β3-class integrins. In vivo, αIIb was highly expressed by invasive trophoblast cells in the ectoplacental cone and trophoblast giant cells of the parietal yolk sac. These data demonstrate that trafficking of αIIb regulates adhesion between trophoblast cells and fibronectin as invasion of the endometrium commences. © 2004 Elsevier Inc. All rights reserved.
Rout, U. K., Wang, J., Paria, B. C., & Armant, D. R. (2004). α5β1, αVβ3 and the platelet-associated integrin αIIbβ3 coordinately regulate adhesion and migration of differentiating mouse trophoblast cells. Developmental Biology, 268(1), 135–151. https://doi.org/10.1016/j.ydbio.2003.12.010