Expression And Its Function Of TACE In Mouse Endometrium During Estrus Cycle And Early Pregnancy

Backgroud: Embryo implantation is one of the earliest events in reproduction of humans and mammals that determines whether pregnancy will develop successfully or not. Successful implantation depends on invasive embryo, acceptive endometrium and their synchronization. There is an extremely short period in uterine receptivity for embryo implantation, which is called"implantation window". Implantation in all mammals involves shedding of zona pellucida, followed by orientation, attachment and adhesion, and invasion of the embryo to the endometrium. Embryo implantation is involved in the regulation of large number of genes and the enrollment of complicated regulatory systems. Tumour necrosis factor alpha converting enzyme (TACE) was identified by its ability to cleave tumor necrosis factor alpha at its physiological processing site[1]. TACE/ADAM17 gene is approximately 50 kb and contains 19 exons. It located on mouse chromosome 12 and human chromosome 2p25[2,3]. TACE belongs to a transmembrane glycoprotein family, i.e., the'A Disintegrin And Metalloprotease'family. This family falls within the metzincin superfamily. TACE is a multi-domain, type I transmembrane protein, in which opening reading frame encodes 824 amino acids. It has common sequences of ADAMs: signal peptide, propeptide, catalytic domin, disintegrin domin, cysteine-rich domin, transmembrane domin, cytoplasmic domin. By proteolytic removal of the extracellular domain of numerous transmembrane proteins, TACE can be concerned with cell adhesion, fusion, signal transduction and so on. Recent research indicated that TACE was expressed in human uterine epithelia during the receptive phase[4] and was overexpressed in most mammary tumors , renal cell carcinomas, hepatic cellular cancers, prostatic carcinomas pancreatic carcinomas and colon carcinomas[5,6]. Now it is accepted that the process of embryo implantation is extremely similar with that of tumor invasion and metastasis. So it is inferred that TACE may play the same role in the process of embryo implantation. However there is no report about the expression rule of TACE in mouse endometrium, which is a meaningful subject.Objective: To investigate the expression of TACE gene in mouse endometrium during estrus cycle and early pregnancy and to analyze its role in embryo implantation.Methods:1. Mouse endometria during estrus cycle and early pregnancy were gathered in the study. There were 11 groups, and each group contained 10 mice. TACE mRNA expression was detected in mouse endometrium by Reverse transcript-polymerase chain reaction (RT-PCR) technique.2. Mouse endometria during estrus cycle and early pregnancy were gathered in the study. There were 11 study groups, and each group contained 10 mice. TACE protein expression was detected in mouse endometrium by immunohistochemistry3. In vivo: TACE antibody or normal saline was injected into the horn of uterus on d3, and the number of embryo implantation was counted on d9. Each group contained 6 mice Results:1. RT-PCR: TACE mRNA was expressed in mouse endometrium during estrus cycle and early pregnancy. The expression of TACE mRNA in estrus stage group was higher than that in other 3 groups during estrus cycle(P<0.01). The expression of TACE mRNA in pregnant groups was higher than that in estrus stage group(P<0.05) and appeared an increased trend as time passing by, reaching the maximum at pregnancy d4.2. Immunohistochemistry: TACE protein was located in kytoplasm and apical surface of luminal epithelium and gland epithelium, and in stromal cell during pregnancy d3～d6. Immunohistochemical analysis showed the same result as RT-PCR.3. In vivo: The number of implantation embryo in the horn of uterus which received TACE antibody was fewer than another horn which received saline. In oneself control, the number of implantation embryo in treated horn of uterus was fewer than that in untreated horn in experiment group. However, there was no significant difference between the untreated horn and the treated horn which received the injection of saline.conclusion: TACE mRNA and protein in mouse endometrium during early pregnancy were higher than those during estrus cycle, and they were extremely expressed during d3～d6. It maybe promote endometrium synchronous development, blastocyst adhesion and invasion by proteolytic removal of the extracellular domain of numerous transmembrane proteins. In vivo experiment results showed the number of implantation embryo in the horn of uterus, which was injected TACE antibody into, was fewer than that in the untreated horn. It was implied that TACE might play an important role in the process of embryo implantation.