CD52 expression is induced in the mouse uterus at the time of embryo implantation

CD52 is a GPI anchor protein present in lymphocytes, the epithelial cells of the epididymis and sperm. It has been reported that male reproductive tract CD52 induces antibodies interfering with sperm function and causes infertility. CD52 is also expressed in ovulated cumulus cells in female reproductive tissues. In the present study, we examined the distribution and the mechanism of regulation of CD52 in the uterus. CD52 expression was evaluated in uterine tissue recovered at 0.5, 4.5, 8.5 and 12.5 dpc (days post-coitum). Immunohistochemistry, RT-PCR, Western blotting and gel shift analysis were performed to determine localization and transcriptional regulation of CD52. Cd52 mRNA and CD52 protein were found to increase simultaneously from 0.5 to 4.5 dpc. Gel shift analysis revealed that NKX2.2, a transcriptional factor, binds to the promoter region of the Cd52 gene. CD52 and NKX2.2 were co-localized in the endometrium of the uterus. Pathway analysis using Ingenuity pathway analysis predicted that Cd52 is associated with genes involved in the formation of uterosomes which are necessary for embryo attachment. These findings suggest that CD52 synthesis is regulated by NKX2.2 at a transcriptional level, and that Cd52 may be a member of the network of genes regulating uterine receptivity for embryo implantation.