The role of UPK1b in the uterus during the Window of Implantation

Shani Agron

Embryo implantation into the uterus wall is one of the obligatory phases for successful pregnancy. This process can occur only during a specific time known as the window of implantation (WOI), in which the uterus is ready to accept the blastocyst. Nowadays in vitro fertilization (IVF) treatments are the answer for fertility problems, with high rate of egg fertilization and embryo formation. However, implantation process is considered as the limiting step for the success of the treatment. Clinical evidence suggests that endometrial biopsies significantly improve the rate of implantation, clinical pregnancies and live births by provoking an inflammatory response that modulates the expression of specific genes that may increase uterine receptivity.

In our lab we preformed global  microarray analysis which revealed a large number of genes that were expressed differentially in human endometrium during the implantation window in general and after endometrial biopsy particularly. One of the prominently up regulated genes was the bladder transmembranal protein, UPK1b, the expression of which in the the uterus is herein reported for the first time. We found that localization of this gene is restricted to the endometrial epithelial cells, the first uterine layer that contacts the embryo.

Moreover we found that UPK1b is upregulated by progesterone, the dominant sex hormone during the WOI. The aim of our study is to understand its role in the development of receptive endometrium that allows successful implantation.