The Rule And Significance Of Active β-Catenin During Early Pregnancy

Objective:To investigate the molecular mechanism of activeβ-catenin during the implantation process, expression, distribution and dynamic change of activeβ-catenin protein in endometria from non-pregnant mice and on day 3 to day 7 of pregnant mice were respectively detected by immuno- histochemistry, western blotting and indirect immunofluorescence histochemistry.Methods:1. The animal model of NIH pregnant mice was found. Endometrium from day 3-7 in early pregnancy mice were used to following study. Pregnant mice were randomly divided into 5 groups(d3, d4, d5, d6, d7) and non-pregnant (d0) mice was control group. The endometria of non-pregnant and pregnant mice were collected, and then were immediately stored at -80℃for further test.3. The expression of activeβ-catenin protein in the endometria of non-pregnant and pregnant mice were detected by western blotting, immunohistochemistry and indirect immunofluorence histochemistry.4. Pregnant mice were injected mifepristone in the nape of the neck on day 2 of pregnancy and the expression of activeβ-catenin protein were analysized on d3, d4, d5, d6, d7 of pregnancy, respectively.Result:1. The result showed that the expression of activeβ-catenin protein in pregnant mice endometria is higher than that of non-pregnant(P<0.05), and showed a raise trend from day 3 to day 4, reached the maximum level on day 4 of pregnancy.2. By immunohistochemistry, the positive expression of activeβ-catenin protein has been observed in the endometria of pregnant and non-pregnant mice and mainly located at the cytoplasm of epithelia and stromal cells. The activeβ-catenin expression of endometria in pregnant mice is higher than that of non-pregnant and reached the maximum level on day 4 of pregnancy. On pregnant day 5 to day 7, the expression level of activeβ-catenin porotein is down-regulated, but there are no statistically difference compared with d4 (P>0.05).3. The result of indirect immunofluorescence analysis showed the both of activeβ-catenin and E-cadherins antigens were expressed concomitantly in luminal epithelium and gland epithelium on day 3 and day 4 of pregnancy, the both of them were expressed concomitantly in stromal cells, vascular endothelium and embryo after day 5 of pregnancy.4. The result of western blot analysis is consistent with that of the immunohistochemistry and immunofluorence histochemistry.5. The expression of activeβ-catenin protein in mifepristone group were significantly lower than those of the two control groups(1,3-propanediol group and control group of pregnancy)(p <0.01),and there was no peak expression on day 4 of pregnancy.Conclusion1. The expression of activeβ-catenin protein has been observed in the endometria of non-pregnant and pregnant mice, and is higher in pregnant mice than that of non-pregnant mice. The result suggested that activeβ-catenin might involved in the whole process of blastocyst implantation and play an important role.2. According to the high expression of activeβ-catenin on day 4 and its distribution rule in the endometria of early pregnant mice, we suggested that activeβ-catenin might participated in the adhesion/invasion of blastocyst during implantation and angiogenesis of endometrium. It influences the action between trophoblast and endometrium to make the best reception of endometrium via promoting the adhesion of cell-extracellular matrix .3. The expression of activeβ-catenin in the endometria of pregnant mice were significantly inhibited by Mifepristone. The observation suggest that activeβ-catenin might play an important roles in signal transudation of embryo implantation and its expression may be up-regulated by progestogen.