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Mediator complex subunit 12 (MED12) is the most frequently mutated gene in uterine leiomyomas (ULs)-with a frequency of up to 85%-suggesting that it plays key roles in the pathogenesis of ULs. However, there is no established relationship between genetic alteration and other risk factors of UL pathogenesis such as the patient's age, weight, and race. In this meta-analysis, we established an association between these risk factors and the frequency of MED12 mutation. We also established the relationship between MED12 mutation with the number and size of tumors in a patient. A systematic literature search was performed for studies published by May 2020 and performed a meta-analysis according to PRISMA guidelines. Twenty-five studies were included in the analysis, representing 3151 tissue samples. MED12 mutations were more common in Black (74.5%) as compared to White (65.8%) and Asian (53.2%) patients. There was no significant relationship between the patient's age and the frequency of mutations (OR 0.73, 95% CI 0.38 to 1.41). MED12 mutations were common in patients barring small-sized (OR 1.46, 95% CI 1.09 to 1.95) multiple (OR 0.39, 95% CI 0.17 to 0.92) tumors. For the patient's weight, studies were few and the outcome was not statistically significant. This meta-analysis provides valuable information on the relationship between the patient's clinical characteristics and frequency of MED12 mutation among patients barring ULs, which is relevant for understanding the pathogenesis of ULs.Protocol registration: The protocol was registered in PROSPERO with registration number CRD42019123439.

Ubiquitination is a regulatory mechanism that occurs after protein translation. To date, few studies have reported on ubiquitination during embryo implantation. We used real-time quantitative polymerase chain reaction, immunohistochemistry, and Western blotting analyses to analyze the expression of speckle-type pox virus and zinc finger (POZ) protein (SPOP; an adapter of E3 ligases of ubiquitination) in mouse uteri during early pregnancy and pseudopregnancy using an artificially induced decidualization model and a steroid hormone–processing model. At the same time, we established an artificially induced decidualization in vitro model. We observed that SPOP regulates endometrial stromal cell decidualization in mice and that hormones regulate the expression of SPOP. This study suggests that ubiquitination may be involved in embryonic implantation.

Previous studies have shown that microRNAs are involved in the process of implantation. They play an important role in cell growth and proliferation. DROSHA is the microRNA-processing enzyme and is required for the maturation of microRNAs. However, its expression and function during early pregnancy in mice still remain unclear. In the present study, we analyzed the expression pattern of DROSHA in the mouse uterus during early pregnancy, pseudopregnancy, artificially induced decidualization, and in the ovariectomized mouse uterus using real-time quantitative polymerase chain reaction, Western blotting analyses, and immunohistochemistry. We found that DROSHA was spatiotemporally expressed in decidualizing stromal cells during early pregnancy and in pseudopregnant mice in which decidualization was artificially induced. In the ovariectomized mouse uterus, the expression of DROSHA was upregulated after progesterone treatment. In a stromal cell culture model, the expression of DROSHA gradually increased with the progression of stromal decidualization. Taken together, our findings suggest that DROSHA is involved in stromal decidualization and may play an important role in embryo implantation in mice.

Embryo implantation is a dynamic physiological process involving morphological and molecular changes in the endometrium during the pre-receptivity, receptivity, and implantation phases. A comprehensive analysis of messenger RNA (mRNA) and microRNA (miRNA) profiles during implantation will likely provide new clues to elucidate the underlying mechanisms governing embryo implantation. We characterized the mRNA and miRNA transcriptomes using next generation sequencing (NGS) of the endometrium 1 day postcoitum (dpc) and 4dpc and the implantation site (IMS) and inter-implantation (IIM) site of the endometrium on 5dpc. Real-time quantitative polymerase chain reaction was performed on selected miRNAs and their predicted target mRNAs to validate their negatively correlated expression. Statistical analysis of the data based on Gene Ontology (GO) group annotation and Kyoto Encyclopedia of Genes and Genomes pathway analysis demonstrated that the genes with significant expression at the IIM site were primarily involved in glucose, protein, and lipoprotein metabolism to provide energy for embryo implantation, while the genes identified at the IMS were involved in RNA functions to produce proteins in support of embryo development and trophoblast invasion. Extracellular matrix (ECM)-receptor interactions between cells and the ECM was the most remarkable event during implantation. The miRNA-mRNA interaction network unraveled the regulatory relationship between miRNAs and mRNAs. Hub miRNAs (mmu-miR-96 and mmu-miR-200b) were identified to target B-cell lymphoma 2 (Bcl-2), Kruppel-like factor 13 (Klf13), and Progesterone receptor (PGR), which are associated with the preparation of the receptive condition or the maintenance of early pregnancy.

Embryo implantation is a complex process requiring reciprocal interactions between implantation-competent blastocysts and receptive uteri. Accumulating literatures have indicated that T cells are involved in this process. The first signal mediated by T-cell receptor/CD3 complex and the second signal delivered by costimulatory molecules are essential for the differentiation of T cell into an effector cell. Expression and function of CD28, an important costimulatory molecule, during early pregnancy in mice is still unclear. In the present study, we investigated the expression pattern of CD28 in mouse uterus during early pregnancy and pseudopregnancy by real-time quantitative polymerase chain reaction, Western blotting, in situ hybridization, and immunohistochemistry (IHC). We found that injection of the uterine horn with CD28 antisense oligodeoxynucleotides leads to a decreased number of implantation sites. The expression pattern of CD3 protein examined by IHC is similar to that of CD28. These findings suggest that CD28 participates in the process of embryo implantation in mice, which might play its role through delivering the second costimulatory signal.

Embryo implantation is a complicated process involving a series of endometrial changes that depend on differential gene expression. MicroRNAs (miRNAs) are important for regulation of gene expression. Previous studies have shown that miRNAs may participate in the regulation of gene expression during embryo implantation. To explore the role of endometrial miRNAs in early murine pregnancy, we used microarrays to investigate whether miRNAs were differentially expressed in the mouse endometrium on pregnancy day 4 (D4) and day 6 (D6). The results demonstrated that 17 miRNAs were upregulated and 18 were downregulated (>2-fold) in D6 endometria compared to D4. We identified that mmu-miR-193 exhibited the highest upregulation on D6, and the upregulation of mmu-miR-193 before embryo implantation could reduce the embryo implantation rate. Further, we demonstrated that mmu-miR-193 influenced embryo implantation by regulating growth factor receptor-bound protein 7 expression. In summary, our study suggests that mmu-miR-193 plays an important role in embryo implantation.

Successful mouse embryo implantation requires a receptive uterus and an activated blastocyst. A large number of genes, cytokines, and other factors are involved in the process. MicroRNAs (miRNAs) regulate the expression of many genes, and previous studies have investigated the relationship between miRNA expression and embryo implantation. In this study, we show that mmu-microRNA-200a (mmu-miR-200a) is expressed in a spatiatemporal manner during implantation in mouse uterus and found that phosphatase and tensin homolog (PTEN), SON, and programmed cell death 4 (Pdcd4) are the target genes of mmu-miR-200a by bioinformatics analysis. In vitro gain and loss of function experiments confirm that PTEN, a critical gene for cell proliferation and apoptosis, is the target gene of mmu-miR-200a. Our experiments also show that injection of the uterine horn with mmu-miR-200a lentivirus leads to a decreased implantation rate. Collectively, our results suggest that mmu-miR-200a affects embryo implantation by regulating PTEN protein expression. Thus, clarifying the physiological functions of uterine miRNAs will help to elucidate the embryo implantation process and may even contribute to curing infertility and inventing new contraceptives.

During the reproductive cycle, a number of genes controlling endometrial changes are regulated by DNA methylation, a common epigenetic modification. Because dietary folate affects DNA methylation, we determined whether a folate-deficient diet (FDD) alters DNA methylation in endometria of pseudopregnant mice, focusing on the homeobox A10 (Hoxa10) promoter. Mice were given an FDD or control diet for 40 to 45 days and examined on day 5 of pseudopregnancy. Compared to control mice, FDD mice had lower folate levels in liver and serum (P = .004). However, the FDD did not significantly affect DNA methylation within the cytosine-guanine dinucleotide (CpG)-rich Hoxa10 promoter, even when specific CpG sites were examined (P > .05). In endometrial tissue sections, the localization of anti-Hoxa10 staining was unchanged in FDD mice. Therefore, folate deficiency did not significantly affect promoter methylation or expression of Hoxa10.