Expression And Regulation Of Claudin-3 In Mouse Endometrium During Early Pregnancy

Claudin-3 is one of tight junction components. As a primary barrier, tight junction plays animportant role in cytoplasma diffusion by paracellular pathway, and it can play as a fence betweenbasal region of lateral membranes and apical region to constitute and maintain the polarity ofepithelial cells and endothelial cells. During early pregnancy, the endometrial cells can form atemporal permeability barrier around the embryo to protect it from the maternal harmfulenvironment. Normally, the polarized epithelial cells can regulate the transport of fluids through thelateral tight junctions, thus these cells can protect the embryo by acting as a permeability barrier. Inthis study, we used in situ hybridization to examine the expression patterns of claudin-3 in mouseperi-imptantation endometrium. Furthermore, we examined the factors which affect the expressionof claudin-3 in mouse peri-implantation endometrium by using artificial decidualization,pseudopregnancy, delayed implantation and ovariectomized mice. The results suggested that duringthe normal pregnancy, the highest level of claudin-3 expression occurred on days 3 and, and thesignal located on luminal epithelium and glandular epithelium, but claudin-3 expression was not inendometrial stroma cells. A weak signal was detected in the luminal epithelium surrounding theembryo on day 5 and in the primary decidualized zone on day 6. On days 1, 2, 7 and 8 of pregnancy,no signals were detected. In the pseudopregnant mice, the expression pattern of claduin-3 was alikenormal pregnancy. In the ovariectomized mice, progesterone had no effects on claudin-3 expression,but estrogen or a combination of estrogen and progesterone up-regulated claudin-3 expression. Inthe uterus under delayed implantation, no signal was detected. After delayed implantation wasactivated by estrogen, claudin-3 expression was detected in luminal epithelium surrounding theembryo. In conclusion, our results suggested that claudin-3 had a stage-special expression patternin mouse peri-implantation endometrium and was regulated by embryos and estrogen, Claduin-3may be closely related to embryo implantation and decidualization.