Expression Of PCNA In Mouse Endometrium And Its Function During The Blastocyst Implantation

Backgroud:Blastocyst implantation is the first step of mammal's reproduction which determines whether pregnancy will develop successfully. In recent years, genetic, environmental pollution and other factors induce more and more unpregnency. However, implantation rate of IVF-ET is low and still have not been overcame now. So it is necessary to do some researches to this important reproduction event of blastocyst implantation.Blastocyst implantation process involves apposition, adhesion and invasion. Successful implantation needs synchronic development of blastocyst and endometrium, which leads endometrium to be receptive in the period of"implantation window", and the receptive endometrium becomes a adsorptive surface, it also induces stromal cell decidualization. Endometrial receptive changes include plenty of genic regulations and complicate regulatory factors, and cell proliferation, apoptosis and other complicate molecular events play important roles in the change. In addition, recent researches suggest that cell proliferation and apoptosis participate in every step of reproduction, so researches of these genes are popular now in blastocyst implantation.PCNA ( Proliferating cell nuclear antigen) was found in SLE serum in 1978. It is named for it exists in proliferating cells. At first it was only a inner marker to indicate cell proliferating. However, in recent years, plenty of researches showed PCNA possesses numerous of intricate biological functions, which acts important in cell proliferation, apoptosis and cell cycle regulation. Jeff R applied microarray and in-situ hybridization discovered that PCNA is one of up-regulate gene in endometrium during preimplantation, and presumed it participates endometrial proliferation, and may act in a concerted fashion for remodeling of the endometrium during blastocyst attachment and invasion. Researches also suggested that the expression of PCNA correlates to tumor invasion, and blastocyst implantation and tumor invasion have remarkable similar biological behavior. So we presume that PCNA may participate in blastocyst implantation process. However, the role of PCNA during blastocyst implantation have not been researched at present stage, so it is significant to do.Objective: To investigate the expression rule of PCNA in the mice's endometrium and analysis it's role in blastocyst implantation.1. Endometrium o f mice in the early phase of unpregnancy and pregnant d2, d3, d4, d5, d6, d7entered into the study. There were 7 groups, each group had 10 mice. PCNA mRNA and protein expression were detected in the endometria of mice by real-time fluorescence quantitative PCR (FQ-PCR) and immuno- histochemical technique respectively.2. The number of blastocyst implantation was registered by injecting PCNA monoclonal antibody in horn of uterus at 20:00 on the pregnant d3.Results:1. The PCNA mRNA expressed in every group. The PCNA/β-actin mRNA of d2 and d7 compared to d0 had no significant difference, other pregnant groups were all higher, and at pregnant d4 and d5 the expression reached the maximum.2. Immunohistochemical analysis showed PCNA protein expressed in nuclei of every group. Positive stromal-cell quantity showed gradual hoist trend as days past in d0 to d5 groups, d6 and d7 groups showed gradual descent trend. Positive glandular epithelium cells mainly existed in d0, d3, d6 groups, and Positive luminal epithelium cells mainly existed in d3, d6, d7 groups. The rule of positive cell quantity was similar to mRNA.3. The numbers of blastocyst in horn of uterus which was injected PCNA monoclonal antibody is fewer than that of saline injected.Conclusion: PCNA expressed strongly in"implantation window"suggested that it may participate in some pathway to initiate cell proliferation and apoptosis, which induced endometrial receptive change to ensure blastocyst implanting in this period and prepared for decidualization. PCNA monoclonal antibody was used to intercept the physiologic function. We found that the number of blastocyst implantation markedly decreased, and deduced that PCNA may act important in blastocyst implantation.