The Expressions Of MiR-155 And MiR-146a In The Process Of Embryo Implantation And Their Functions

ObjectiveDue to the modern lifestyle,social pressure,late childbirth and the two-child policy in China,assisted reproduction technology become an option for more and more people with primary infertility or secondary infertility.Assisted reproduction technology is an effective treatment for these patients.Even the technology is becoming more and more mature,the success rate still can be improved.Both the high-quality embryo formation and the good endometrial receptivity are essential factors for a successful pregnancy.Non-coding small RNA(miRNAs),as a new discovery,play an important role in embryo implantation and endometrial decidualization by regulating expressions of endometrial receptivity-related genes at the transcriptional or post-transcriptional level.The expression profiles of miRNA in the endometrium of rat peri-endometrium were observed in the early stage of the study group.This article aims to investigate expressions and functions of miR-155,miR-146a during embryo implantation.MethodsPart Ⅰ Expression changes of hsa-miR-155,hsa-miR-146a in decidual tissues of induced abortion and in the mid-secretive phase endometrium of ovulation-nornal women.According to inclusion criteria and exclusion criteria,we collected one group pf samples from outpatients who obtained early induced abortions in our hospital and the other group of samples from ovulation-normal women of childbearing age who provided the mid-secretive phase endometrium as volunteers.We compare the pathological sections from the two groups to observed the morphological changes of the endometrium before and after implantation.Then RNAs were respectively extracted from the two groups.The real-time fluorescence quantitative polymerase chain reactions were performed with miRNA probes.After detecting expressions of hsa-miR-155 and hsa-miR-146a in the endometrial tissue from the two groups.We analysis changes of the two miRNAs during the decidualization of secretory endometrium.Part Ⅱ Expressions of mmu-miR-155 and mmu-miR-146a in early pregnancy of mice and their influences on embryo implantation.The 8-week-old female ICR mice with regular estrous cycle were caged with the males of the same species in their reproductive age to collect the endometrial tissues on the 1st,4th,5th,6th day of pregnancy respectively(D1,D4,D5,D6).In the meanwhile,the uterine tissues of the embryo implantation point and non-implantation point were collected on the 5th day of pregnancy.Hematoxylin-eosin staining was performed to these collected tissues to observe the morphological changes during early pregnancy.The real-time fluorescence quantitative polymerase chain reactions were used to detect expressions of mmu-miR-155 and mmu-miR-146a in the collected tissues.Based on previous experimental results,8-week-old female ICR mice with regular estrous cycle were caged with males in their reproductive age.On the 3th day of pregnancy,mmu-miR-155 agomir or mmu-miR-146a agomir was injected into the mouse’s uterine hom near the ovary during abdominal operation,and NC agomir was injected into the mouse’s uterine horn on the contralateral as a control.The mice were executed on the 8th day of pregnancy and we count the number of embryo implantation to confirm the influences of the two miRNAs.Result1.In clinical trials,expressions of hsa-miR-155 and hsa-miR-146a in normal early decidua tissues were significantly lower than those in the mid-secretive phase endometrium of ovulation-normal women.The difference was statistically significant(p<0.05).2.With the increase of pregnant days,from D1,D4,D5 to D6,the decidualization was enhanced gradually and the expressions of mmu-miR-155,mmu-miR-146a in endometrial tissue gradually decreased.The expressions of mmu-miR-155,mmu-miR-146a after embryo implantation were significantly lower than those before embryo implantation.At the same time,the expressions of mmu-miR-155 and mmu-miR-146a in endometrial tissue of embryo implantation site on D5 were significantly lower than those of non-implantation site.All the differences were statistically significant(P<0.05).3.The number of embryo implantations in the uterus with the injection of mmu-miR-155 agomir or mmu-miR-146a agomir was significantly lower than that of NC agomir(p<0.05).ConclusionWith the increase of pregnancy time,both miR-155 and miR-146a significantly decrease in the endometrial tissues of the embryo implantation process of early pregnancy.miR-155 and miR-146a may up-regulate the related target genes to affect decidualization during the process of embryo implantation.These results provid a new target for the study of embryo implantation.