Temporal and spatial expression of AIF in the mouse uterus during early pregnancy.

Apoptosis-inducing factor (AIF) is a phylogenetically old, bifunctional protein with a pro-apoptotic function and redox activity. AIF regulates apoptosis and also plays a role in the defense against stress depending on its subcellular localization. Embryo implantation is a complicated process, in which an activated blastocyst interacts with a receptive uterus. The expression and regulation of AIF were investigated in this study in the mouse uterus during early pregnancy, pseudopregnancy, delayed implantation, artificial decidualization and under hormonal treatment using in situ hybridization, immunohistochemistry and real-time PCR. During early pregnancy, temporally and spatially regulated patterns of AIF expression were found in the mouse uterus; AIF expression in the luminal epithelium and glandular epithelium is regulated by steroid hormones; AIF mRNA expression in the stroma is influenced by the active blastocyst; and AIF protein was found to be located in the cytoplasm rather than the nucleus through confocal microscope. Our data suggest that AIF might play an important role during mouse embryo implantation and that the role of AIF might be implemented through its physiological activity rather than through its pro-apoptotic function in the mouse uterus during this period.