Grant: Discovery Grants Program - Individual

Recognition and maintenance of pregnancy are complex processes involving both maternal and embryonic signals. In the rodents during early implantation, endometrial epithelial cells undergo apoptosis. Later, the stromal cells undergo decidualization, which is followed by decidua basalis (DB) regression, involving apoptosis of decidual cells. The failure to establish such a communication has been shown to be the most important cause of infertility among mammals. However, the molecular mechanisms governing endometrial cell apoptosis are not yet defined. Interestingly, our laboratory has showed that individual TGF-b isoforms (TGF-b1, -b2 and -b3) are differently expressed in the uterus during rat pregnancy: TGF-b1 and TGF-b2 are present during implantation and DB regression, whereas TGF-b3 isoform is only present during DB regression. We have also provided evidence that distinct TGF-b can activate distinct signaling pathways in endometrial cells. This strongly suggests that TGF-b can play an important role depending of the situation during pregnancy and we hypothesize that sex steroids progesterone and 17b-estradiol, the hormones of pregnancy, might also be involved in this process. The overall and long term objective of the proposed research program is to examine and understand the regulation of expression as well as the endocrine, paracrine and autocrine activity of the TGF-b isoforms in the endometrium during the two important phases of pregnancy: 1) embryo implantation and 2) DB regression. Epithelial and stromal cells as well as whole rat uteri from different Days of pregnancy, pseudopregnat and estrous cycle will be used for in vivo and in vitro studies. Experimental approaches will include molecular and biochemical techniques, upregulation with expression vectors and down-regulation of key proteins using shRNA, biochemical in vivo inhibition of signaling pathways, apoptosis in situ and by flow cytometry and immunofluorescence. Information gained from these studies will help to understand the importance of TGF-b isoforms during these critical reproductive situations and will provide important clues for successful establishment and maintenance of pregnancy.