Uterine Foxl2 regulates the adherence of the Trophectoderm cells to the endometrial epithelium

miR-149-PARP-2 Signaling Regulates E-cadherin and N-cadherin Expression in the Murine Model of Endometrium Receptivity

Cadherins play an essential role in the attachment of the blastocyst to the endometrium, a process known as endometrial receptivity. Loss of E-cadherin expression is essential during the process, while the expression level of the other cadherin, N-cadherin, has been reported to be altered in cases of infertility. Both E-cadherin and N-cadherin can be regulated by members of the PARP family. Specifically, PARP-2, which is under the epigenetic control of miR-149, has been observed to promote E-cadherin expression in other human cells. We investigated the roles of E-cadherin and N-cadherin in endometrial receptivity using mouse models for normal endometrial receptivity, pseudopregnancy, and LPS-induced endometrial receptivity failure. E-cadherin and phosphorylated E-cadherin were predominantly expressed during pre-receptive stages as well as in the implantation site of the receptive stage, which were observed reduced during the later stages of implantation in both implantation and non-implantation regions, while N-cadherin was detected only at pre-receptive stages. E-cadherin and N-cadherin were also seen in the uterus during pseudopregnancy, showing a downregulation trend during receptive and post-receptive stages. LPS-induced failed endometrial receptivity showed upregulation of E-cadherin and downregulation of N-cadherin. The E-cadherin expression promoter, GSK-3, was lost and its suppressor, SLUG was upregulated during normal course of endometrial receptivity in mouse model, while GSK-3 was increased during LPS-induced failed embryo implantation. In an in vitro model of embryo implantation, E-cadherin expression is promoted by PARP-2 and regulated by miR-149 epigenetically in human endometrium epithelial cells. In conclusion, E-cadherin is predominantly expressed during pre-receptive stage and promoted by PARP-2, which is regulated by miR-149 in the endometrial epithelial cells.

Differential expression of protein disulfide isomerase (PDI) in regulating endometrial receptivity in humans

Estrogen and progesterone regulate the expression of endometrial proteins that determine endometrial receptivity for embryo implantation. The protein disulfide isomerase (PDI) family of proteins play a diverse role in regulating protein modification and redox function. Although the role of PDIs in cancer progression has been widely studied, their role in endometrial receptivity is largely unknown. We have focused on the expressions of PDIA1, PDIA2, PDIA3, PDIA4, PDIA5, and PDIA6 isoforms in endometrial epithelium under the influence of estrogen and progesterone and investigated their functional role in regulating endometrial receptivity. We found PDIA1-6 transcripts were expressed in endometrial epithelial Ishikawa, RL95-2, AN3CA, and HEC1-B cell lines. The expression of PDIA1 was low and PDIA5 was high in HEC1-B cells, whereas PDIA2 was high in both AN3CA and HEC1-B cells. In Ishikawa cells, estrogen (10 and 100 nM) upregulated PDIA1 and PDIA6, whereas estrogen (100 nM) downregulated PDIA4 and PDIA5; and progesterone (0.1 and 1 μM) downregulated transcript expressions of PDIA1-6. In human endometrial samples, significantly lowered transcript expressions of PDIA2 and PDIA5 were observed in the secretory phase compared with the proliferative phase, whereas no change was observed in the other studied transcripts throughout the cycle. Inhibition of PDI by PDI antibody (5 and 10 μg/mL) and PDI inhibitor bacitracin (1 and 5 mM) significantly increased the attachment of Jeg-3 spheroids onto AN3CA cells. Taken together, our study suggests a role of PDI in regulating endometrial receptivity and the possibility of using PDI inhibitors to enhance endometrial receptivity.

Identification of biomarkers correlated with diagnosis and prognosis of endometrial cancer using bioinformatics analysis

Endometrial cancer (EC) is one of the most common malignancies in the female genital system, characterized by high mortality and recurrence rates. This study attempted to screen key genes and potential prognostic biomarkers for EC using bioinformatics analysis. Twenty-seven normal endometrial tissues and 135 EC samples were collected from four Gene Expression Omnibus (GEO) databases, then we identified the differentially expressed genes (DEGs) and conducted downstream analyses. Moreover, we screened hub genes by constructing a protein-protein interaction (PPI) network. Finally, we assessed the prognostic values and molecular mechanism of the potential prognostic genes using the Kaplan-Meier curve and Gene Set Enrichment Analysis (GSEA). As a result, 28 upregulated and 94 downregulated genes were determined after gene integration of these four GEO data sets. Gene Ontology analysis indicated that DEGs were mainly involved in transcriptional regulation and cell proliferation. The Kyoto Encyclopedia of Gene and Genome pathway analysis primarily related to transcriptional misregulation and apoptosis. Moreover, the PPI analysis revealed 10 hub genes (JUN, UBE2I, GATA2, WT1, PIAS1, FOXL2, RUNXI, EZR, TCF4, and NR2F2) with a high degree of connectivity, among them, the expression tendency of nine genes except UBE2I were consistent with messenger RNA level from The Cancer Genome Atlas data. Furthermore, only FOXL2, TCF4, and NR2F2 were significantly correlated with prognosis of EC patients, and their low expression associated biological pathways were enriched in the cell cycle and fatty acid metabolism. In conclusion, this study identified three key genes as biomarkers and potential therapeutic targets of EC on the basis of integrated bioinformatics analysis. The findings will improve our comprehension of the molecular mechanisms underlying the pathogenesis and prognosis of EC.

Transcriptome and regulatory maps of decidua-derived stromal cells inform gene discovery in preterm birth

While a genetic component of preterm birth (PTB) has long been recognized and recently mapped by genome-wide association studies (GWASs), the molecular determinants underlying PTB remain elusive. This stems in part from an incomplete availability of functional genomic annotations in human cell types relevant to pregnancy and PTB. We generated transcriptome (RNA-seq), epigenome (ChIP-seq of H3K27ac, H3K4me1, and H3K4me3 histone modifications), open chromatin (ATAC-seq), and chromatin interaction (promoter capture Hi-C) annotations of cultured primary decidua-derived mesenchymal stromal/stem cells and in vitro differentiated decidual stromal cells and developed a computational framework to integrate these functional annotations with results from a GWAS of gestational duration in 56,384 women. Using these resources, we uncovered additional loci associated with gestational duration and target genes of associated loci. Our strategy illustrates how functional annotations in pregnancy-relevant cell types aid in the experimental follow-up of GWAS for PTB and, likely, other pregnancy-related conditions.

Prolonged Effect of Seminal Plasma on Global Gene Expression in Porcine Endometrium

Seminal plasma (SP) deposited in the porcine uterine tract at the time of mating is known to elicit an initial response that is beneficial for pregnancy outcome. However, whether SP has any long-term effect on alterations in endometrial molecular and cellular processes is not known. In this study, using microarray analyses, differential changes in endometrial transcriptome were evaluated after Day 6 of SP-infusion (6DPI) or Day 6 of pregnancy as compared to corresponding day of estrous cycle. Both, pregnancy and SP induced significant changes in the endometrial transcriptome and most of these changes were specific for a particular group. Functional analysis of differentially expressed genes (DEGs) using Ingenuity Pathway Analysis revealed that inhibition in immune response was affected by both pregnancy and SP infusion. Long-term effects of SP included differential expression of genes involved in inhibition of apoptosis, production of reactive oxygen species and steroid biosynthesis, and activation of processes such as proliferation of connective tissue cells and microvascular endothelial cells. Moreover, interleukin-2 and interferon-γ was identified to be responsible for regulating expression of many DEGs identified on 6DPI. The present study provides evidence for the long-term effects of SP on porcine endometrium that can be beneficial for pregnancy success.

Increased FOXL2 expression alters uterine structures and functions†

The transcription factor forkhead box L2 (FOXL2) regulates sex differentiation and reproductive function. Elevated levels of this transcription factor have been observed in the diseases of the uterus, such as endometriosis. However, the impact of elevated FOXL2 expression on uterine physiology remains unknown. In order to determine the consequences of altered FOXL2 in the female reproductive axis, we generated mice with over-expression of FOXL2 (FOXL2OE) by crossing Foxl2LsL/+ with the Progesterone receptor Pgrcre model. FOXL2OE uterus showed severe morphological abnormality including abnormal epithelial stratification, blunted adenogenesis, increased endometrial fibrosis, and disrupted myometrial morphology. In contrast, increasing FOXL2 levels specifically in uterine epithelium by crossing the Foxl2LsL/+ with the lactoferrin Ltficre mice resulted in the eFOXL2OE mice with uterine epithelial stratification but without defects in endometrial fibrosis and adenogenesis, demonstrating a role of the endometrial stroma in the uterine abnormalities of the FOXL2OE mice. Transcriptomic analysis of 12 weeks old Pgrcre and FOXL2OE uterus at diestrus stage showed multiple signaling pathways related with cellular matrix, wnt/β-catenin, and altered cell cycle. Furthermore, we found FOXL2OE mice were sterile. The infertility was caused in part by a disruption of the hypophyseal ovarian axis resulting in an anovulatory phenotype. The FOXL2OE mice failed to show decidual responses during artificial decidualization in ovariectomized mice demonstrating the uterine contribution to the infertility phenotype. These data support that aberrantly increased FOXL2 expressions in the female reproductive tract can disrupt ovarian and uterine functions.

FOXL2 is a Progesterone Target Gene in the Endometrium of Ruminants

Forkhead Box L2 (FOXL2) is a member of the FOXL class of transcription factors, which are essential for ovarian differentiation and function. In the endometrium, FOXL2 is also thought to be important in cattle; however, it is not clear how its expression is regulated. The maternal recognition of pregnancy signal in cattle, interferon-Tau, does not regulate FOXL2 expression. Therefore, in the present study, we examined whether the ovarian steroid hormones that orchestrate implantation regulate FOXL2 gene expression in ruminants. In sheep, we confirmed that FOXL2 mRNA and protein was expressed in the endometrium across the oestrous cycle (day 4 to day 15 post-oestrus). Similar to the bovine endometrium, ovine FOXL2 endometrial expression was low during the luteal phase of the oestrous cycle (4 to 12 days post-oestrus) and at implantation (15 days post-oestrus) while mRNA and protein expression significantly increased during the luteolytic phase (day 15 post-oestrus in cycle). In pregnant ewes, inhibition of progesterone production by trilostane during the day 5 to 16 period prevented the rise in progesterone concentrations and led to a significant increase of FOXL2 expression in caruncles compared with the control group (1.4-fold, p < 0.05). Ovariectomized ewes or cows that were supplemented with exogenous progesterone for 12 days or 6 days, respectively, had lower endometrial FOXL2 expression compared with control ovariectomized females (sheep, mRNA, 1.8-fold; protein, 2.4-fold; cattle; mRNA, 2.2-fold; p < 0.05). Exogenous oestradiol treatments for 12 days in sheep or 2 days in cattle did not affect FOXL2 endometrial expression compared with control ovariectomized females, except at the protein level in both endometrial areas in the sheep. Moreover, treating bovine endometrial explants with exogenous progesterone for 48h reduced FOXL2 expression. Using in vitro assays with COS7 cells we also demonstrated that progesterone regulates the FOXL2 promoter activity through the progesterone receptor. Collectively, our findings imply that endometrial FOXL2 is, as a direct target of progesterone, involved in early pregnancy and implantation.

Connecting links between genetic factors defining ovarian reserve and recurrent miscarriages

PURPOSE

Approximately 1-2% of the women faces three or more successive spontaneous miscarriages termed as recurrent miscarriage (RM). Many clinical factors have been attributed so far to be the potential risk factors in RM, including uterine anomalies, antiphospholipid syndrome, endocrinological abnormalities, chromosomal abnormalities, and infections. However, in spite of extensive studies, reviews, and array of causes known to be associated with RM, about 50% cases encountered by treating physicians remains unknown. The aims of this study were to evaluate recent publications and to explore oocyte-specific genetic factors that may have role in incidence of recurrent miscarriages.

METHOD

Recent studies have identified common molecular factors contributing both in establishment of ovarian reserve and in early embryonic development. Also, studies have pointed out the relationship between the age-associated depletion of OR and increase in the risk of miscarriages, thus suggestive of an interacting biology. Here, we have gathered literature evidences in establishing connecting links between genetic factors associated with age induced or pathological OR depletion and idiopathic RM, which are the two extreme ends of female reproductive pathology.

CONCLUSION

In light of connecting etiological link between infertility and RM as reviewed in this study, interrogating the oocyte-specific genes with suspected roles in reproductive biology, in cases of unexplained RM, may open new possibilities in widening our understanding of RM pathophysiology.