Regulation of Urokinase Plasminogen Activator Production in Implanting Mouse Embryo: Effect of Embryo Interaction with Extracellular Matrix1

Abstract

Embryo implantation in the mouse is an invasive process and requires the action of proteinases, including plasminogen activator (PA) and metalloproteinases. After the implanting embryo establishes close contact with the endometrium, the invasion process begins, at least in part, through interactions of the embryo with the extracellular matrix in the endometrium. This study determined whether embryo interaction with extracellular matrix components would affect the secretion of PA in vitro. PA in vitro. Mouse embryos were collected from the uterus on Day 3.5 of development, just before implantation, and were cultured dishes precoated with bovine serum, plasma fibronectin, or BSA (control). Embryos cultured on serum- or fibronectin-coated dishes secretes significantly more PA than those cultured on BSA. The effect of fibronectin was inhibited by hexapeptides that contained the integrin-recognizing Arg-Gly-Asp sequence. This indicates that the action of fibronectin in enhancing PA secretion is mediated through its receptor (integrins) in the embryo. Fibronectin fragments reproduced the effect of the whole fibronectin molecule, suggesting that the clustering of integrins by specific ligands is responsible, at least in part, for the increase PA secretion. The increase in PA secretion was a specific response to fibronectin rather than a reflection of increased total protein secretion, and was at least partially a result of the increased steady-state level of PA mRNA in the cultured embryos. Laminin was as effective as fibronectin in promoting PA secretion. Epidermal growth factor increased PA secretion, probably by promoting the interaction of the embryos with the extracellular matrix. In summary, our findings indicate that the interactions of the implanting embryos with their extracellular matrix may regulate trophoblast invasion by controlling PA secretion.

Transcriptional Profiling of Equine Conceptuses Reveals New Aspects of Embryo-Maternal Communication in the Horse1

“…The plasminogen system is one of the proteinases implicated in trophoblast invasion [42]. Here we report the down-regulation of plasminogen activator and antiplasmin precursor, as well as the up-regulation of PAI.…”

Nuclear Translocation of Hand-1 Acts as a Molecular Switch to Regulate Vascular Radiosensitivity in Medulloblastoma Tumors: The Protein uPAR Is a Cytoplasmic Sequestration Factor for Hand-1

“…3A), suggesting their role in early embryogenesis and development (42)(43)(44)(45). Earlier, we showed that increased expression of uPAR with IR treatment induces the angiogenic ability of medulloblastoma cells (7,44).…”

Optimisation of in vitro culture conditions in B6CBF1 mouse embryos

“…The application of mineral oil significantly reduced embryo development compared with the presence of paraffin oil although these two types of oil have been broadly used in embryo culture [2,10,11,37]. A recent study indicates that the use of mineral oil significantly reduces the rate of pig embryos developing to the blastocyst stage after IVF [38].…”

“…An M16 medium [2] was extensively used, but not employed in this study because an early study has shown that the M16 medium is inferior to the CZB medium during the culture of mouse embryos [3]. Based on the rationale that in vitro culture conditions need to be as similar as possible to those found in the oviducts, Quinn et al [4] developed a culture medium that was biochemically very similar to that of human tubal fluid (HTF).…”