Expression And Regulation Of Plekhs1 During The Transition Of Uterine Receptivity In Mouse

Embryo implantation is an important stage during pregnancy. The successful implantation depends primarily on three factors: embryo activation, uterine receptivity and interaction between activated embryo and receptive uterus. Endometrial receptivity is affected mainly by estrogen and progesterone secreted by ovary. In addition to ovarine hormones, certain molecules(such as KLF5), which are not regulated by ovarin hormones, can also regulate the state of uterus.The PH domain is present in many signaling and cytoskeletal proteins, mediating extracellular and intracellular signaling. Plekhs1 is PH domain containing family S member1. So far there has not been any reports about expression and functions of Plekhs1. We found that Plekhs1 was highly expressed in luminal epithelium before implantation and the expression decreased significantly after implantation by Microarray analysis. We speculate that this gene might be related with the uterine receptivity.The aim of this study was to investigate the relationship between Plekhs1 and mouse uterine receptivity by using various mouse models including early pregnant mice model, pseudopregnant model, steroid hormone processing model, delayed implantation and activation model, delayed and activation model in pseudopregnancy and tubal ligation model, and quantitative RT-PCR, in situ hybridization, immunohistochemistry, Western blot and TALEN technology.The expression of plekhs1 mRNA in the luminal epithelium was very strong from day 1 to day 4 of pregnancy, and especially from day 3 to day 4. The transcripts of plekhs1 was hardly to be detected from day 5 to day 8 of pregnancy. The signals of plekhs1 protein were strongly detected from day 1 to day 5 of pregnancy, and especially from day 4 to day 5. In the pseudopregnant uteri, plekhs1 gene was highly expressed in luminal epithelium from day 1 to day 5, but not be detected on day 6 and days 7; however, it was re-detected on days 8. There were stong signals detected in the luminal epithelium in the ovaryectomized mice, and in the ovaryectomized mice treated with estrogen and/or progesterone. Under the delayed-implantation condition, there was strong plekhs1 signal detected in the luminal epithelim. Once delayed implantation was terminated by estrogen treatment and embryo initiated into uterus, the m RNA of plekhs1 was not detected. In delayed implantation and activation model of pseudopregnant mice, there was strong plekhs1 signal detected in the luminal epithelim when the uterus was in the pre-receptive or receptive status(3 ng E2 treated for 24 h, 25 ng E2 treated for 7 h and 50 ng E2 treated for 3 h), while no signal was detected when the uterus was in the nonreceptive status(25 ng E2 treated for 24 h and 50 ng E2treated for 7 h). The plekhs1 gene was highly expressed in luminal epithelium on day 5 of pregnancy in bilateral uterotubal junction-ligated pregnant mice. In unilateral uterotubal junction-ligated pregnant mice, there was strong plekhs1 m RNA signal detected in luminal epithelium on day 5 of pregnancy in the ligated site, while no plekhs1 signal was detected in the non-ligated site uterus. In case of few implantation sites(one or two) in the uterus on day 5 of pregnancy, the stronger plekhs1 signal could be detected, the further away from the implantation site. There was no signal detected in the inter-implantation site close enough to the implantation site.The results of our research showed that plekhs1 may be closely related to the transition of uterine receptivity. The plekhs1 gene was strongly expressed when the uterine environment was neutral and it was not expressed when the uterus became nonreceptive. The results suggest that plekhs1 might has a regulatory role in the transition of uterine receptivity.In order to further study the functions of plekhs1 in vivo, we have constructed a TALEN vector targeting plekhs1 gene for the generation of plekhs1 knockout mice.