To study the role of during embryo implantation in rat. expression in rat early pregnancy was detected by Northern blot. The relation between and predicted and confirmed by bioinformatics method, dual-luciferase activity assay, Western blot and immunohistochemistry. The role of was detected by MTS, Edu and chamber assays. The expression level of on gestation day 5–8 (g.d. 5–8) was higher than on g.d. 3–4 in uteri of pregnant rat. was mainly localized in the superficial stroma/primary decidual zone, luminal and glandular epithelia. The expression of was not significantly influenced by pseudopregnancy, but the activation of delayed implantation and experimentally induced decidualization significantly promoted expression. Over-expression of in human endometrial stromal cells (ESCs) inhibited cell proliferation, migration and invasion. Knockdown of promoted cell proliferation and invasion. The results of recombinant luciferase reporters showed that could bind to the 3¢-untranslated region (UTR) of ( ) to inhibit translation. Uterine may be involved in the successful pregnancy, especially during the process of blastocyst implantation through regulating . This study may have the potential to provide new insights into the understanding of function during embryo implantation.
Every successful pregnancy requires proper embryo implantation. Low implantation rate is a major problem during infertility treatments using assisted reproductive technologies. Here we report a newly discovered molecular influence on implantation through the lysophosphatidic acid (LPA) receptor LPA3 (refs 2-4). Targeted deletion of LPA3 in mice resulted in significantly reduced litter size, which could be attributed to delayed implantation and altered embryo spacing. These two events led to delayed embryonic development, hypertrophic placentas shared by multiple embryos and embryonic death. An enzyme demonstrated to influence implantation, cyclooxygenase 2 (COX2) (ref. 5), was downregulated in LPA3-deficient uteri during pre-implantation. Downregulation of COX2 led to reduced levels of prostaglandins E2 and I2 (PGE2 and PGI2), which are critical for implantation. Exogenous administration of PGE2 or carbaprostacyclin (a stable analogue of PGI2) into LPA3-deficient female mice rescued delayed implantation but did not rescue defects in embryo spacing. These data identify LPA3 receptor-mediated signalling as having an influence on implantation, and further indicate linkage between LPA signalling and prostaglandin biosynthesis.
BACKGROUND Repeated implantation failure (RIF) is a major problem encountered in IVF. We have previously reported that RIF-IVF patients have a different endometrial gene expression profile during the window of implantation. Considering microRNA (miRNA) function in post-transcriptional regulation of gene expression, the aim of the study was to evaluate the involvement of miRNA in defects of endometrial receptivity. METHODS We used TaqMan miRNA array cards to identify the miRNAs differentially expressed in the secretory endometrium of RIF-IVF patients when compared with fertile women, and bioinformatics tools to identify their predicted targets and the molecular networks they may affect. RESULTS Comparing miRNA expression profiles, we identified 13 miRNAs, differentially expressed in RIF endometrial samples, that putatively regulate the expression of 3800 genes. We found that 10 miRNAs were overexpressed (including miR 145, 23b and 99a) and 3 were underexpressed. Using our previous gene expression analysis, we paralleled miRNA–mRNA expression profiling. By this means, we identified novel and previously characterized miRNA-regulated molecular pathways such as adherens junctions, cell adhesion molecules, Wnt-signaling, p53 signaling and cell cycle pathways. Consistent with the miRNA-predicted targets, mRNA levels of N-cadherin, H2AFX, netrin-4 and secreted frizzled-related protein-4, belonging to the cell adhesion molecules, Wnt signaling and cell cycle pathways were lower in RIF-IVF patients. CONCLUSIONS To our knowledge, this is the first study to evaluate the differential expression of miRNAs in the secretory endometrium of RIF-IVF patients. We suggest that the RIF-associated miRNAs could be exploited as new candidates for diagnosis and treatment of embryo implantation failures.
The molecular changes that support implantation in eutherian mammals are necessary to establish pregnancy. In marsupials, pregnancy is relatively short, and although a placenta does form, it is present for only a few days before parturition. However, morphological changes in the uterus of marsupials at term mimic those that occur during implantation in humans and mice. We investigated themolecular similarity between term pregnancy in the marsupials and implantation in eutherian mammals using the gray short-tailed opossum (Monodelphis domestica) as a model. Transcriptomic analysis shows that term pregnancy in the opossum is characterized by an inflammatory response consistent with implantation in humans and mice. This immune response is temporally correlated with the loss of the eggshell, and we used immunohistochemistry to report that this reaction occurs at the materno-fetal interface. We demonstrate that key markers of implantation, including Heparin binding EGF-like growth factor and Mucin 1, exhibit expression and localization profiles consistent with the pattern observed during implantation in eutherian mammals. Finally, we show that there are transcriptome-wide similarities between the opossum attachment reaction and implantation in rabbits and humans. Our data suggest that the implantation reaction that occurs in eutherians is derived froman attachment reaction in the ancestral therianmammal which, in the opossum, leads directly to parturition. Finally, we argue that the ability to shift from an inflammatory attachment reaction to a noninflammatory period of pregnancy was a key innovation in eutherian mammals that allowed an extended period of intimate placentation.
The implantation process is complex, requiring reciprocal interactions between implantation-competent blastocysts and the receptive uterus. Because microRNAs (miRNAs) have major roles in regulating gene expression, we speculated that they participate in directing the highly regulated spatiotemporally expressed genetic network during implantation. Here, we show that two miRNAs, mmu-miR-101a and mmu-miR-199a*, are spatiotemporally expressed in the mouse uterus during implantation coincident with expression of cyclooxygenase-2, a gene critical for implantation. More interestingly, our in vitro gain- and loss-of-function experiments show that cyclooxygenase-2 expression is posttranscriptionally regulated by these two miRNAs. We report on miRNA-mediated regulation of uterine gene expression in the context of implantation. We believe that many other critical genes related to this process are also regulated by miRNAs. Thus, elucidating the physiological roles of uterine miRNAs will help us better understand the genetic control of implantation, the gateway to a successful pregnancy.
Failure of embryo implantation is a major limiting factor in early pregnancy and assisted reproduction. Determinants of implantation include the embryo viability, the endometrial receptivity, and embryo-maternal interactions. Multiple molecules are involved in the regulation of implantation, but their specific regulatory mechanisms remain unclear. MicroRNA (miRNA), functioning as the transcriptional regulator of gene expression, has been widely reported to be involved in embryo implantation. Recent studies reveal that miRNAs not only act inside the cells, but also can be released by cells into the extracellular environment through multiple packaging forms, facilitating intercellular communication and providing indicative information associated with physiological and pathological conditions. The discovery of extracellular miRNAs shed new light on implantation studies. MiRNAs provide new mechanisms for embryo-maternal communication. Moreover, they may serve as non-invasive biomarkers for embryo selection and assessment of endometrial receptivity in assisted reproduction, which improves the accuracy of evaluation while reducing the mechanical damage to the tissue. In this review, we discuss the involvement of miRNAs in embryo implantation from several aspects, focusing on the role of extracellular miRNAs and their potential applications in assisted reproductive technologies (ART) to promote fertility efficiency.
Abstract A cross-sectional study was carried out at the Australian Concept Infertility Medical Centre from June 2014 to June 2015 to relate serum kisspeptin levels on human chorionic gonadotrophin (HCG) day with pregnancy outcome after intracytoplasmic sperm injection (ICSI). A total of 176 women aged 20 to 42 years, with regular menstrual cycles, normal thyroid function and prolactin levels selected for ICSI were included in the study. Patients with uterine fibroids, metabolic disorders, short agonist and antagonist protocol were excluded. Long protocol for down-regulation of ovaries was observed and kisspeptin levels were estimated on HCG day. Results were categorized into groups: Group A, non-pregnant with β-HCG 25 mIU/ml and cardiac activity on transvaginal scan. Kisspeptin levels were significantly higher in Group B versus Group A ( P < 0.001), independently associated with positive pregnancy ( r = 0.388; P < 0.001), but just borderline with endometrial thickness ( r = 0.294; P = 0.05). The area under the curve was highest for kisspeptin, 0.784 (95% CI, 0.681 to 0.886) for positive pregnancy, which indicated that kisspeptin measured on HCG day can be used as a marker for success of treatment in women after ICSI.
Implantation is a key stage during pregnancy, as the fate of the embryo is often decided upon its first contact with the maternal endometrium. Around this time, DCs accumulate in the uterus; however, their role in pregnancy and, more specifically, implantation, remains unknown. We investigated the function of uterine DCs (uDCs) during implantation using a transgenic mouse model that allows conditional ablation of uDCs in a spatially and temporally regulated manner. Depletion of uDCs resulted in a severe impairment of the implantation process, leading to embryo resorption. Depletion of uDCs also caused embryo resorption in syngeneic and T cell-deficient pregnancies, which argues against a failure to establish immunological tolerance during implantation. Moreover, even in the absence of embryos, experimentally induced deciduae failed to adequately form. Implantation failure was associated with impaired decidual proliferation and differentiation. Dynamic contrast-enhanced MRI revealed perturbed angiogenesis characterized by reduced vascular expansion and attenuated maturation. We suggest therefore that uDCs directly fine-tune decidual angiogenesis by providing two critical factors, sFlt1 and TGF-beta 1, that promote coordinated blood vessel maturation. Collectively, uDCs appear to govern uterine receptivity, independent of their predicted role in immunological tolerance, by regulating tissue remodeling and angiogenesis. Importantly, our results may aid in understanding the limited implantation success of embryos transferred following in vitro fertilization.