Identification of uterine genes induced by embryo during mice implantation.

点击翻译按钮获取中文摘要

In this project, we sought to identify the genes involved in the implantation process by subtracting cDNA constructed from the uteri of non-pregnant mice from cDNA from those of pregnancy day 5 mice. One of the identified cDNA encoded the calcium binding protein D-9k (Calbindin). Northern blot analysis showed that the size of the transcript was the same as rat calbindin mRNA, and that it was expressed in the uteri of pregnancy day 5 mice. We found that the expression of calbindin mRNA increased on day 3 of pregnancy when the serum progesterone concentration is high. In fact, progesterone induced a marked increase in the expression of calbindin mRNA.In situ hybridization showed that the uterine expression of calbindin mRNA disappeared in the glandular epithelium on day 5 of pregnancy. In the pseudopregnant mice, the expression of calbindin mRNA was observed in the glandular epithelium on day 5, suggesting that this molecule is regulated not only by the sex steroid hormones, but also by the embryonal signal. To examine this possibility, we performed the embryo transfer experiments. While calbindin mRNA was detected in the glandular epithelium of the control uterine horn, it was not detected in the embryo-transferred horn 36 h after embryo transfer. These results indicated that the expression of calbindin mRNA in the glandular epithelium was suppressed by the presence of blastocysts on day 5 of pregnancy.In conclusion we could found that embryonic signals modulate the endometrium during implantation. We are now analyzing other cDNA clones cloned from subtracted cDNA library. This approach will contribute towards the clarification of reproductive physiology.