Mechanisms of murine trophoblast interaction with laminin.

Implantation of the mouse embryo depends on the interaction of the trophoblast and the uterine environment, which includes an extracellular matrix with abundant amounts of laminin. The experiments reported here analyzed the interaction of trophoblast with laminin in vitro. Secondary trophoblast attachment and spreading on laminin matrices was competitively inhibited in the presence of the laminin peptides YIGSR (Tyr-Ile-Gly-Ser-Arg), RGD (Arg-Gly-Asp), and IKVAV (Ile-Lys-Val-Ala-Val). Substrates of multiple, but not single, peptides supported attachment and spreading of trophoblast. The presence of laminin-binding proteins on trophoblast cell surfaces were detected by immunofluorescence using antiserum directed against a fusion protein encoded by the full-length clone for the 32-kDa laminin-binding protein. Immunoblotting with the same antiserum identified immunoreactive proteins of 33, 41, 45, 62, and 76 kDa in trophoblast lysates. The antiserum also inhibited the spreading of trophoblast on laminin matrices.