Expression And Function Of Pin1 During Mouse Embryo Implantation And Decidualization

Embryo implantation and decidualization are two key links in the early pregnancy process,which play a vital role in the establishment and maintenance of normal pregnancy.Pin1(protein interaction with NIMA1)is a peptidyl-prolyl isomerase(PPIase)whose imbalance can lead to the occurrence of many diseases including tumors.However,there are no detailed studies on the regulation and function of Pin1 in the pregnant uterus,and there is no report on the regulation and function of Pin1 in the process of mouse embryo implantation and decidualization.In order to explore the relationship of Pin1 between embryo implantation and decidualization in early pregnancy,the localization and expression of Pin1 in the uterus of early pregnancy in mice was first detected by immunohistochemistry,RT-PCR and Western-Blot experiments.The results showed that Pin1 was expressed on the luminal epithelium and glandular epithelium of the uterus on D1 and D4 of pregnancy.On D5 of pregnancy,it was mainly expressed in the stromal cells around the implantation sites.During D6 to D8 of pregnancy,it began to be expressed in the secondary decidua and embryo.RT-PCR results showed that the expression of Pin1 at the m RNA level gradually increased in the uterus of pregnant mice from D1 to D8.Western-Blot results further verified that as the pregnancy progressed,the protein expression of Pin1 in the mouse uterus gradually increased,and the expression at the implantation sites was higher than that at the non-implantation sites on D5 of pregnancy.In the artificially induced decidualization model,Pin1 is expressed on the luminal epithelium and glandular epithelium of the uterus of control mice,while it is highly expressed in the secondary decidual area in the uterus of induced decidualization mice,which is similar to normal pregnancy D6～D8.When mouse stromal cells were treated with estrogen and progesterone to induce decidualization in vitro,the expression of Pin1 was significantly increased after decidualization.We treated pregnant mice with Juglone,a specific inhibitor of Pin1,to study the role of Pin1 in mouse embryo implantation and decidualization.we found that the number of embryo implantation sites in the uterus of pregnant D5 mice after intraperitoneal injection of Juglone significantly reduced,and the size of the decidua of pregnancy D7 was significantly smaller than the control group.RT-PCR results verified that the effector gene of estrogen,Muc1,as a resistance molecule,was abnormally up-regulated in the uterus of pregnant D5 mice with Juglone-treated.The decidualization marker molecule Dtprp was significantly down-regulated in the uterus of pregnant D7 mice with Juglone-treated.The progesterone effector genes Hand2 and Hoxa10 were down-regulated in the uterus of pregnant D5 and D7 mice with Juglone-treated,indicating that inhibiting the expression of Pin1 is unfavorable for mouse embryo implantation and decidualization.As a member of the Wnt signaling pathway,β-catenin plays an important role in the process of embryo implantation and decidualization.Its expression in the mouse uterus is similar to Pin1.Studies have shown that Pin1 can regulate the subcellular localization of β-catenin,so we speculate that there is a connection between the two.Western-Blot results showed that the expression of Pin1 and β-catenin protein was significantly reduced during the process of embryo implantation and decidualization after intraperitoneal injection of Juglone.After treating mouse stromal cells with 1μM and 5μM Juglone inhibitors in vitro,the protein expression of Pin1 and β-catenin decreased,and the inhibitory effect was the most obvious at a concentration of 5μM.In cells that induced decidualization in vitro,Pin1 si RNA was transfected,and it was found that after knocking down the expression of Pin1,the expression of β-catenin decreased,and the expression of the decidual marker molecule Dtprp also decreased.Finally,we used the obtained clinical specimens(endometrial secretion in the middle of the normal menstrual cycle as a control and the endometrium at the same period of recurrent implantation failure)to detect the expression of Pin1 in the endometrium between the two samples by RT-PCR experiment.As a result,it was found that the expression of Pin1 in the endometrium of patients with recurrent implantation failure was significantly down-regulated.In summary,we speculate that Pin1 plays an important role in regulating embryo implantation and decidualization.