Expression and regulation of ATF6α in the mouse uterus during embryo implantation

Background: ATF6 alpha, one of the sensor proteins in the stress signaling pathway of the endoplasmic reticulum, is located in the membrane of the endoplasmic reticulum. To date, the physiological function of ATF6 alpha in the process of embryo implantation has not been reported. Methods: In this study, the expression pattern of ATF6 alpha in the mouse uterus during peri-implantation and the estrous cycle was detected by real-time PCR, western blot and immunohistochemistry. Results: ATF6 alpha mRNA and protein levels were higher in the uterus near the implantation site on day 5 and were intensely expressed in the secondary decidual zone (SDZ) on days 7-8. In the uteri of pseudopregnant mice, ATF6 alpha mRNA and protein levels were lower on day 5 than on other days. The activating blastocyst and artificial decidualization had an obvious effect of increasing the expression of ATF6 alpha. In addition, the expression of ATF6 alpha was affected by progesterone (P-4) and estrogen (E-2) in ovariectomized mice. This finding is further supported by evidence from mice during the estrous cycle. Conclusions: Thus, we have concluded that ATF6 alpha may play an important role during embryo implantation and decidualization.