The role of T-lymphoma invasion and metastasis inducing protein 1 in early pregnancy in mice.

T-lymphoma invasion and metastasis inducing protein 1 (Tiam1) is involved in tumorigenesis processes, including cell migration, adhesion and invasion, proteolysis, cytoskeleton reorganization, cell morphological transformation and intracellular signaling. These processes are also critical for embryo implantation, although the role of Tiam1 during embryo implantation remains poorly understood. The aim of this study was to investigate the spatio-temporal expression of Tiam1 in endometria of mice comparing early pregnancy and non-pregnancy. Fluorescent quantitative-PCR and immunohistochemical analysis showed that the expression of Tiam1 mRNA and protein in endometria of pregnant mice was higher than that of non-pregnant mice, and gradually increased from Day 1 of pregnancy reaching a maximum level on Day 5 and then declining on Days 6 and 7. Immunohistochemistry showed that Tiam1 protein was present in luminal epithelium from Days 3-5 of pregnancy and in gland epithelium from Days 4 to 6 and enhanced significantly in stromal cells on Day 5, regarded as the 'implantation window' period. The number of implantation sites was greatly decreased by the intrauterine injection with anti-Tiam1 polyclonal antibody in the early morning of the Day 4 of pregnancy. These findings suggest that Tiam1 might play an important role in embryo implantation in mice.