Trophoblasts, invasion, and microRNA

Expression of IMP3 and LIN28A RNA-Binding Proteins in Placentas of Patients with Pre-Eclampsia with and without Severe Features

BACKGROUND

this study aimed to determine the expression of RNA-binding oncofetal proteins IMP3 and LIN28A in extravillous (EVT) and villous trophoblast (VT) cells of placentas from pre-eclamptic (PE) pregnancies to better understand the pathogenesis of PE.

METHODS

placental tissue of 10 patients with PE with severe features, 10 patients with PE without severe features and 20 age-matched healthy pregnancy controls were analyzed by immunohistochemistry, double immunofluorescence and qPCR.

RESULTS

We found a decreased percentage of IMP3-positive EVT cells in PE with and without severe features compared to that of the healthy control (p < 0.001). IMP3 expression was significantly low in VT of PE placentas compared to that of the healthy control (p = 0.002). There was no significant difference in LIN28A expression between groups of PE and the control group. Additionally, we noticed the trend toward downregulation of IMP3 mRNA and LIN28A mRNA in severe PE compared to that of healthy controls.

CONCLUSIONS

We demonstrated that IMP3 expression is decreased in EVT and VT cells of placentas from pregnancies complicated with both PE with and without severe features. However, additional functional investigations are needed to clarify the role of IMP3 as a potential therapeutic target in the management of PE.

Linking genotype to trophoblast phenotype in preeclampsia and HELLP syndrome associated with STOX1 genetic variants

Preeclampsia is a major hypertensive pregnancy disorder with a 50% heritability. The first identified gene involved in the disease is STOX1, a transcription factor, whose variant Y153H predisposes to the disease. Two rare mutations were also identified in Colombian women affected by the hemolysis, elevated liver enzyme, low platelet syndrome, a complication of preeclampsia (T188N and R364X). Here, we explore the effects of these variants in trophoblast cell models (BeWo) where STOX1 was previously invalidated. We firstly showed that STOX1 knockout alters response to oxidative stress, cell proliferation, and fusion capacity. Then, we showed that mutant versions of STOX1 trigger alterations in gene profiles, growth, fusion, and oxidative stress management. The results also reveal alterations of the STOX interaction with DNA when the mutations affected the DNA-binding domain of STOX1 (Y153H and T188N). We also reveal here that a major contributor of these effects appears to be the E2F3 transcription factor.

Zona pellucida removal modifies the expression and release of specific microRNAs in domestic cat blastocysts

The in vitro culture of domestic cat embryos without the zona pellucida affects their implantation capacity. MicroRNAs (miRNAs) have an important role in embryo-maternal communication and implantation. The objective of this study was to evaluate the expression of specific miRNAs in domestic cat blastocysts cultured without the zona pellucida. Two experimental groups were done: (1) domestic cat embryos cultured with the zona pellucida (zona intact control group, ZI); and (2) cultured without the zona pellucida (zona free group, ZF). The cleavage, morula and blastocyst rates were evaluated. The blastocysts and their spent medium were used for miRNA expression analysis using RT-qPCR (miR-21, miR-24, mi25, miR-29, miR-96, miR-98, miR-103, miR-191, miR-196, miR-199, miR-130, miR-155 and miR-302). The pre-mature microRNAs (pre-miRNAs) and miRNAs were evaluated in the blastocysts and only miRNAs were evaluated in the spent medium. No differences were observed in the cleavage, morula and blastocyst rates between the ZF and ZI groups (P > 0.05). For miRNAs analysis, miR-103 and miR-191 had the most stable expression and were selected as internal controls. ZF blastocysts had a higher expression of miR-21, miR-25, miR-29 and miR-199 and a lower expression of miR-96 than their ZI counterparts (P < 0.05). Furthermore, higher levels of miR-21, miR-25 and miR-98 were detected in the spent medium of ZF blastocysts (P < 0.05). In conclusion, in vitro culture of domestic cat embryos without the zona pellucida modifies the expression of miR-21, miR-25, miR-29, miR-199 and miR-96 at the blastocyst stage and the release of miR-21, miR-25 and miR-98.

MicroRNAs targeting peroxisome proliferator-activated receptor (PPAR) gene are differentially expressed in low birth weight placentae

INTRODUCTION

Peroxisome proliferator-activated receptors (PPARs) are activated by natural ligands like fatty acids and influence placental angiogenesis and pregnancy outcome. However, the underlying molecular mechanisms are not clear. This study aims to investigate the association of maternal and placental fatty acid levels with DNA methylation and microRNA regulation of PPARs in the placentae of women delivering low birth weight (LBW) babies.

METHODS

This study includes 100 women delivering normal birth weight (NBW) baby and 70 women delivering LBW baby. Maternal and placental fatty acids levels were estimated by gas chromatograph. Gene promoter methylation and mRNA expression of PPARs was analyzed using Epitect Methyl-II PCR assay kit and RT-PCR respectively. Expression of miRNAs targeting PPAR mRNA were analyzed using a Qiagen miRCURY LNA PCR Array on RT-PCR.

RESULTS

Placental docosahexaenoic acid (DHA) levels and placental mRNA expression of PPARα and PPARγ were lower (p < 0.05 for all) in the LBW group. Differential expression of miRNAs (upregulated miR-33a-5p and miR-22-5p; downregulated miR-301a-5p, miR-518d-5p, miR-27b-5p, miR-106a-5p, miR-21-5p, miR-548d-5p, miR-17-5p and miR-20a-5p) (p < 0.05 for all) was observed in the LBW group. Maternal and placental polyunsaturated fatty acids and total omega-3 fatty acids were positively associated while saturated fatty acids were negatively associated with expression of miRNAs (p < 0.05 for all). Placental expression of miRNAs were positively associated with birth weight (p < 0.05 for all).

DISCUSSION

Our data suggests that maternal fatty acid status is associated with changes in the placental expression of miRNAs targeting PPAR gene in women delivering LBW babies.

Effect and mechanism of microRNA-515-5p in proliferation and apoptosis of trophoblast cells in preeclampsia via manipulating histone deacetylase 2

Preeclampsia (PE) refers to a pregnancy-specific disease that begins with the placenta. Differentially expressed microRNAs (miRs) are a feature of PE. This study tried to elicit the functional mechanism of miR-515-5p in trophoblast cell behaviors in PE. First, HTR-8/SVneo cells were transfected with miR-515-5p mimic or miR-515-5p inhibitor. Then, relative expression levels of miR-515-5p and histone deacetylase 2 (HDAC2) in HTR-8/SVneo cells were determined by reverse transcription-quantitative polymerase chain reaction. The potential binding site of miR-515-5p and HDAC2 was predicted on Targetscan and their binding relationship was verified via dual-luciferase assay. Proliferation, apoptosis, invasion, and migration of HTR-8/SVneo cells were assessed via cell counting kit-8, flow cytometry, Transwell, and wound healing assays, respectively. Protein levels of Cleaved caspase-3, Bcl-2, and Bax were determined via Western blot. Overexpressed miR-515-5p impeded proliferation and stimulated apoptosis of HTR-8/SVneo cells, and decreased levels of Cleaved caspase-3 and Bax and elevated Bcl-2, whilst opposite results were observed after miR-515-5p inhibition. miR-515-5p targeted HDAC2. Knockdown of HDAC2 annulled the promotional action of miR-515-5p inhibition on proliferative, invasive, and migratory abilities and its antiapoptotic action on HTR-8/SVneo cells. In brief, miR-515-5p affected the proliferation, apoptosis, invasion, and migration of HTR-8/SVneo cells by targeting HDAC2.

MicroRNAs: key regulators of the trophoblast function in pregnancy disorders

The placenta is essential for a successful pregnancy and healthy intrauterine development in mammals. During human pregnancy, the growth and development of the placenta are inseparable from the rapid proliferation, invasion, and migration of trophoblast cells. Previous reports have shown that the occurrence of many pregnancy disorders may be closely related to the dysfunction of trophoblasts. However, the function regulation of human trophoblast cells in the placenta is poorly understood. Therefore, studying the factors that regulate the function of trophoblast cells is necessary. MicroRNAs (miRNAs) are small, non-coding, single-stranded RNA molecules. Increasing evidence suggests that miRNAs play a crucial role in regulating trophoblast functions. This review outlines the role of miRNAs in regulating the function of trophoblast cells and several common signaling pathways related to miRNA regulation in pregnancy disorders.

Placenta-specific protein 1 (PLAC1) expression is significantly down-regulated in preeclampsia via a hypoxia-mediated mechanism

OBJECTIVE

Examine a mechanism of PLAC1 regulation and its potential role in preeclampsia (PE).

MATERIALS AND METHODS

Placental tissue samples and detailed clinical information were obtained through the University of Iowa Maternal Fetal Tissue Bank (IRB# 200910784) from gestational and maternal age-matched control (n = 17) and PE affected pregnancies (n = 12). PLAC1 and PLAC1 promoter-specific expression was measured using quantitative polymerase chain reaction (qPCR) and differences were assessed via the standard ΔΔCt method. In addition, the role of hypoxia in PLAC1 transcription was investigated through the exposure of HTR8/SVneo human trophoblast cells to the hypoxia mimic dimethyloxaloylglycine (DMOG).

RESULTS

PLAC1 expression is seen to be 8.9-fold lower in human placentas affected by preeclampsia in comparison with controls (p < .05). Further, this decrease is paralleled by a significantly lower expression of the P2 or proximal PLAC1 promoter (p < .05). Expression of mediator complex subunit 1 (MED1), a known hypoxia-sensitive transcription coactivator and PLAC1 effector, is significantly correlated with PLAC 1 expression (r2 = 0.607, p < .001). These data suggest that PLAC1 expression is significantly down-regulated in preeclampsia at least in part via a MED1 hypoxia-mediated mechanism.

CONCLUSIONS

We confirm that PLAC1 transcription is suppressed in the placentae of women affected by preeclampsia. We further demonstrate that this suppression is driven through the P2 or proximal PLAC1 promoter. This demonstration led to the identification of the MED1-TRAP cofactor complex as the hypoxia-sensitive driver.

Role of microRNAs in trophoblast invasion and spiral artery remodeling: Implications for preeclampsia

It is now well-established that microRNAs (miRNAs) are important regulators of gene expression. The role of miRNAs in placental development and trophoblast function is constantly expanding. Trophoblast invasion and their ability to remodel uterine spiral arteries are essential for proper placental development and successful pregnancy outcome. Many miRNAs are reported to be dysregulated in pregnancy complications, especially preeclampsia and they exert various regulatory effects on trophoblasts. In this review, we provide a brief overview of miRNA biogenesis and their mechanism of action, as well as of trophoblasts differentiation, invasion and spiral artery remodeling. We then discuss the role of miRNAs in trophoblasts invasion and spiral artery remodeling, focusing on miRNAs that have been thoroughly investigated, especially using multiple model systems. We also discuss the potential role of miRNAs in the pathogenesis of preeclampsia.

The Temporal Profile of Circulating miRNAs during Gestation in Overweight and Obese Women with or without Gestational Diabetes Mellitus

Circulating non-coding microRNAs (miRNAs) are important for placentation, but their expression profiles across gestation in pregnancies, which are complicated by gestational diabetes mellitus (GDM), have not been fully established. Investigating a single time point is insufficient, as pregnancy is dynamic, involving several processes, including placenta development, trophoblast proliferation and differentiation and oxygen sensing. Thus, the aim of this study was to compare the temporal expression of serum miRNAs in pregnant women with and without GDM. This is a nested case-control study of longitudinal data obtained from a multicentric European study (the ‘DALI’ study). All women (n = 82) were overweight/obese (BMI ≥ 29 kg/m²) and were normal glucose tolerant (NGT) at baseline (before 20 weeks of gestation). We selected women (n = 41) who were diagnosed with GDM at 24–28 weeks, according to the IADPSG/WHO2013 criteria. They were matched with 41 women who remained NGT in their pregnancy. miRNA (miR-16-5p, -29a-3p, -103-3p, -134-5p, -122-5p, -223-3p, -330-3p and miR-433-3p) were selected based on their suggested importance for placentation, and measurements were performed at baseline and at 24–28 and 35–37 weeks of gestation. Women with GDM presented with overall miRNA levels above those observed for women remaining NGT. In both groups, levels of miR-29a-3p and miR-134-5p increased consistently with progressing gestation. The change over time only differed for miR-29a-3p when comparing women with GDM with those remaining NGT (p = 0.044). Our findings indicate that among overweight/obese women who later develop GDM, miRNA levels are already elevated early in pregnancy and remain above those of women who remain NGT during their pregnancy. Maternal circulating miRNAs may provide further insight into placentation and the cross talk between the maternal and fetal compartments.

Epigenetic processes during preeclampsia and effects on fetal development and chronic health

Preeclampsia (PE), the leading cause of maternal and fetal morbidity and mortality, is associated with poor fetal growth, intrauterine growth restriction (IUGR) and low birth weight (LBW). Offspring of women who had PE are at increased risk for cardiovascular (CV) disease later in life. However, the exact etiology of PE is unknown. Moreover, there are no effective interventions to treat PE or alleviate IUGR and the developmental origins of chronic disease in the offspring. The placenta is critical to fetal growth and development. Epigenetic regulatory processes such as histone modifications, microRNAs and DNA methylation play an important role in placental development including contributions to the regulation of trophoblast invasion and remodeling of the spiral arteries. Epigenetic processes that lead to changes in placental gene expression in PE mediate downstream effects that contribute to the development of placenta dysfunction, a critical mediator in the onset of PE, impaired fetal growth and IUGR. Therefore, this review will focus on epigenetic processes that contribute to the pathogenesis of PE and IUGR. Understanding the epigenetic mechanisms that contribute to normal placental development and the initiating events in PE may lead to novel therapeutic targets in PE that improve fetal growth and mitigate increased CV risk in the offspring.

Analysis of Circulating microRNA Signatures and Preeclampsia Development

microRNAs are important regulators of cell processes and have been proposed as potential preeclampsia biomarkers. We evaluated serum microRNA expression profiling to identify microRNAs involved in preeclampsia development. Serum microRNA expression profiling was evaluated at 12, 16, and 20 weeks of gestation (WG), and at the time of preeclampsia diagnosis. Two groups were evaluated using TaqMan low-density array plates: a control group with 18 normotensive pregnant women and a case group with 16 patients who developed preeclampsia during the follow-up period. Fifty-three circulating microRNAs were differentially expressed between groups (p < 0.05). Compared with controls, hsa-miR-628-3p showed the highest relative quantity values (at 12 WG = 7.7 and at 20 WG = 3.45) and the hsa-miRs -151a-3p and -573 remained differentially expressed from 16 to 20 WG (p < 0.05). Signaling pathways including cancer-related, axon guidance, Neurotrophin, GnRH, VEGF, and B/T cell receptor, were most commonly altered. Further target gene prediction revealed that nuclear factor of activated T-cells 5 gene was included among the transcriptional targets of preeclampsia-modulated microRNAs. Specific microRNAs including hsa-miRs -628-3p, -151a-3p, and -573 were differentially expressed in serum of pregnant women before they developed preeclampsia compared with controls and their participation in the preeclampsia development should be considered.

Placenta-Derived MicroRNAs in the Pathophysiology of Human Pregnancy

In placental mammals, reproductive success, and maternal-fetal health substantially depend on a well-being placenta, the interface between the fetus and the mother. Disorders in placental cells are tightly associated with adverse pregnancy outcomes including preeclampsia (PE), fetal growth restriction, etc. MicroRNAs (miRNAs) represent small non-coding RNAs that regulate post-transcriptional gene expression and are integral to a wide range of healthy or diseased cellular proceedings. Numerous miRNAs have been detected in human placenta and increasing evidence is revealing their important roles in regulating placental cell behaviors. Recent studies indicate that placenta-derived miRNAs can be released to the maternal circulation via encapsulating into the exosomes, and they potentially target various maternal cells to provide a hormone-like means of intercellular communication between the mother and the fetus. These placental exosome miRNAs are attracting more and more attention due to their differential expression in pregnant complications, which may provide novel biomarkers for prediction of the diseases. In this review, we briefly summarize the current knowledge and the perspectives of the placenta-derived miRNAs, especially the exosomal transfer of placental miRNAs and their pathophysiological relevance to PE. The possible exosomal-miRNA-targeted strategies for diagnosis, prognosis or therapy of PE are highlighted.

Identification of differentially expressed miRNAs in serum extracellular vesicles (EVs) of Kazakh sheep at early pregnancy

MiRNAs-containing extracellular vesicles (EVs) possess the unique function of mediating intercellular communication and participating in many biological processes such as post-transcriptional gene regulation of embryo implantation and placental development. In the present study, Illumina small-RNA sequencing was used to identify differentially expressed (DE) miRNAs in serum EVs of pregnant (P) and non-pregnant (NP) Kazakh sheep at Day 17 from mating. The specifically and differentially expressed miRNAs at early pregnancy in sheep were verified by using RT-PCR. The target genes of DE miRNAs were predicted by bioinformatics software, and the functional and pathway enrichment analysis was performed on Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) terms. A total of 562 miRNAs (210 novel miRNAs) were identified by sequencing, of which 57 miRNAs were differentially expressed, 49 were up-regulated, 8 were down-regulated and 22 novel miRNAs were specifically expressed in the pregnant sheep. Eight highly expressed known miRNA (miR-378-3p, miR-320-3p, miR-22-3p, let-7b, miR-423-3p, miR-221, miR-296-3p, miR-147-3p) in pregnant group were down-regulated in the control group. miRNAs-containing pregnancy-related terms and regulatory pathways regulation were enriched using both GO and KEGG analyses. Moreover, we also envisioned a miRNA-mRNA interaction network to understand the function of miRNAs involved in the early pregnancy serum regulatory network. The results of RT-PCR verification confirmed the reliability of small-RNA sequencing. Among them, miR-22-3p and miR-378-3p were significantly differentially expressed (DE) between pregnant sheep and non-pregnant group (p <  0.01). The site at which oar-miR-22-3p binds MAPK3 was determined with a dual-luciferase system. This is the first integrated analysis of the expression profiles of EV-miRNAs and their targets during early pregnancy in ewes. These data identify key miRNAs that influence the implantation of sheep in the early stage of pregnancy, and provide theoretical basis for further molecular regulatory mechanisms research.

Downregulation of miR-126-3p expression contributes to increased inflammatory response in placental trophoblasts in preeclampsia

MiR-126-3p is a prototype of an endothelial miRNA and has protective effects on endothelial cells. However, little is known about the effects of miR-126-3p on placental trophoblasts. In the present study, we tested the hypothesis that aberrant miR-126-3p expression is present in preeclamptic placenta which contributes to increased inflammatory response in trophoblasts. Placentas were obtained immediately after delivery from normotensive and preeclamptic pregnancies. Villous tissue was either fixed with formalin or used for trophoblast isolation. Trophoblast miR-126-3p expression was assessed by in situ hybridization of formalin-fixed tissue sections and by RT-PCR in cultured syncytiotrophoblasts. Culture medium was collected for measurement of IL-6, TNFα, and 8-Isoprostane production by ELISA and total cellular protein was collected for evaluation of HIF1α expression by Western blot. Effects of overexpression of miR-126-3p in trophoblasts on cytokine production were tested by transfection of pre-mir-126, a precursor of miR-126, into primary isolated trophoblasts. We found that downregulation of miR-126-3p expression was associated with increased IL-6 and TNFα production in trophoblasts from preeclamptic placentas vs. normal placentas. Moreover, transient overexpression of miR-126-3p significantly reduced IL-6 and TNFα production in trophoblasts from both normal and preeclamptic placentas. We further found that increase in miR-126-3p expression not only suppressed hypoxia-induced increases in IL-6 and TNFα production, but also attenuated hypoxia-induced increases in HIF1α expression and 8-Isoprostane production in trophoblasts cultured under hypoxic condition. These results provide plausible evidence that downregulation of miR-126-3p expression reduces anti-inflammatory and anti-oxidative stress activities in placental trophoblasts in preeclampsia.

LncRNA H19-Derived miR-675-5p Accelerates the Invasion of Extravillous Trophoblast Cells by Inhibiting GATA2 and Subsequently Activating Matrix Metalloproteinases

The invasion of extravillous trophoblast (EVT) cells into the maternal decidua, which plays a crucial role in the establishment of a successful pregnancy, is highly orchestrated by a complex array of regulatory mechanisms. Non-coding RNAs (ncRNAs) that fine-tune gene expression at epigenetic, transcriptional, and post-transcriptional levels are involved in the regulatory mechanisms of EVT cell invasion. However, little is known about the characteristic features of EVT-associated ncRNAs. To elucidate the gene expression profiles of both coding and non-coding transcripts (i.e., mRNAs, long non-coding RNAs (lncRNAs), and microRNAs (miRNAs)) expressed in EVT cells, we performed RNA sequencing analysis of EVT cells isolated from first-trimester placentae. RNA sequencing analysis demonstrated that the lncRNA H19 and its derived miRNA miR-675-5p were enriched in EVT cells. Although miR-675-5p acts as a placental/trophoblast growth suppressor, there is little information on the involvement of miR-675-5p in trophoblast cell invasion. Next, we evaluated a possible role of miR-675-5p in EVT cell invasion using the EVT cell lines HTR-8/SVneo and HChEpC1b; overexpression of miR-675-5p significantly promoted the invasion of both EVT cell lines. The transcription factor gene GATA2 was shown to be a target of miR-675-5p; moreover, small interfering RNA-mediated GATA2 knockdown significantly promoted cell invasion. Furthermore, we identified MMP13 and MMP14 as downstream effectors of miR-675-5p/GATA2-dependent EVT cell invasion. These findings suggest that miR-675-5p-mediated GATA2 inhibition accelerates EVT cell invasion by upregulating matrix metalloproteinases.

Unique features and emerging in vitro models of human placental development

Background

The placenta is an essential organ for the normal development of mammalian fetuses. Most of our knowledge on the molecular mechanisms of placental development has come from the analyses of mice, especially histopathological examination of knockout mice. Choriocarcinoma and immortalized cell lines have also been used for basic research on the human placenta. However, these cells are quite different from normal trophoblast cells.

Methods

In this review, we first provide an overview of mouse and human placental development with particular focus on the differences in the anatomy, transcription factor networks, and epigenetic characteristics between these species. Next, we discuss pregnancy complications associated with abnormal placentation. Finally, we introduce emerging in vitro models to study the human placenta, including human trophoblast stem (TS) cells, trophoblast and endometrium organoids, and artificial embryos.

Main findings

The placental structure and development differ greatly between humans and mice. The recent establishment of human TS cells and trophoblast and endometrial organoids enhances our understanding of the mechanisms underlying human placental development.

Conclusion

These in vitro models will greatly advance our understanding of human placental development and potentially contribute to the elucidation of the causes of infertility and other pregnancy complications.

EGF-mediated reduced miR-92a-1-5p controls HTR-8/SVneo cell invasion through activation of MAPK8 and FAS which in turn increase MMP-2/-9 expression

The members of human miR-17-92 cluster are implicated in several cancers and are known to increase cancer cells invasiveness. The present study reports reduced expression of miR-92a-1-5p in EGF treated HTR-8/SVneo trophoblastic cells by NGS and qRT-PCR. Overexpression of miR-92a-1-5p led to significantly reduced EGF-mediated HTR-8/SVneo cells invasion. MAPK8 and FAS were predicted to be miR-92a-1-5p targets, and confirmed to be reduced by qRT-PCR and Western blotting in trophoblast cells overexpressing miR-92a-1-5p. The binding of miR-92a-1-5p to MAPK8 and FAS 3'-UTR was confirmed by Luciferase reporter assay and Rescue assay. EGF increases MMP-2 & MMP-9 expression and reduces TIMP1 expression in HTR-8/SVneo cells. Inhibition of MAPK8 (by SP600125) reduced EGF-mediated MMP-9/TIMP1 ratio and invasion. Similarly, silencing of FAS by siRNA reduced EGF-mediated MMP-2/TIMP1 ratio and invasion. Treatment of HTR-8/SVneo cells with STAT1/3 inhibitors or siRNAs led to loss of EGF-mediated reduction in miR-92a-1-5p levels. Inserting the predicted binding sites of STAT3 present in promoter region of miR-92a-1-5p upstream of Luciferase promoter reduced its expression in presence of STAT3 expression vector. Thus, EGF leads to reduced miR-92a-1-5p expression which may be regulated by STAT1/STAT3 and controls HTR-8/SVneo cells invasion by targeting MAPK8 and FAS, which in turn increases MMP-2/MMP-9 expression.

miR-183-5p suppressed the invasion and migration of HTR-8/SVneo trophoblast cells partly via targeting MMP-9 in preeclampsia

Preeclampsia (PE), a common obstetrical disorder, is characterized by impaired migration and invasion abilities of trophoblastic cells. MicroRNA-183-5p (miR-183) was reported to regulate cell migration and invasion in various types of human cancers; however, its role in the pathogenesis of PE remains elusive. Herein, we investigated the role of miR-183 in HTR-8/SVneo trophoblast cells invasion and migration and explored the underlying mechanism. Our results showed that miR-183 was significantly up-regulated in placental tissues from pregnant women compared with that in normal pregnant women. Overexpression of miR-183 inhibited proliferation, migration and invasion, as well as induced apoptosis in HTR-8/SVneo cells. Otherwise, down-regulation of miR-183 achieved the opposite effects. Bioinformatics prediction and luciferase reporter assay confirmed that matrix metalloproteinase-9 (MMP-9) is a target of miR-183. In addition, MMP-9 expression was significantly down-regulated, and inversely correlated with the miR-183 level in placental tissues from pregnant women with severe PE. Down-regulation of MMP-9 suppressed the trophoblast cell invasion and migration, whereas overexpression of MMP-9 promoted cell invasion and migration in HTR-8/SVneo cells. More importantly, up-regulation of MMP-9 reversed the inhibitory effects of miR-183 on cell invasion and migration in trophoblast cells. Collectively, our findings suggested that miR-183 may play critical roles in the pathogenesis of PE and serve as a potential biomarker for severe PE.

The Role of LIN28-let-7-ARID3B Pathway in Placental Development

Placental disorders are a major cause of pregnancy loss in humans, and 40–60% of embryos are lost between fertilization and birth. Successful embryo implantation and placental development requires rapid proliferation, invasion, and migration of trophoblast cells. In recent years, microRNAs (miRNAs) have emerged as key regulators of molecular pathways involved in trophoblast function. A miRNA binds its target mRNA in the 3ʹ-untranslated region (3ʹ-UTR), causing its degradation or translational repression. Lethal-7 (let-7) miRNAs induce cell differentiation and reduce cell proliferation by targeting proliferation-associated genes. The oncoprotein LIN28 represses the biogenesis of mature let-7 miRNAs. Proliferating cells have high LIN28 and low let-7 miRNAs, whereas differentiating cells have low LIN28 and high let-7 miRNAs. In placenta, low LIN28 and high let-7 miRNAs can lead to reduced proliferation of trophoblast cells, resulting in abnormal placental development. In trophoblast cells, let-7 miRNAs reduce the expression of proliferation factors either directly by binding their mRNA in 3ʹ-UTR or indirectly by targeting the AT-rich interaction domain (ARID)3B complex, a transcription-activating complex comprised of ARID3A, ARID3B, and histone demethylase 4C (KDM4C). In this review, we discuss regulation of trophoblast function by miRNAs, focusing on the role of LIN28-let-7-ARID3B pathway in placental development.

poFUT1 promotes uterine angiogenesis and vascular remodeling via enhancing the O-fucosylation on uPA

Uterine angiogenesis and vascular remodeling play critical roles in determing the normal menstrual cycle and successful pregnancy. Poor uterine angiogenesis usually results in pregnancy failure. Protein O-fucosyltransferase 1 (poFUT1) is the key enzyme responsible for O-fucosylated glycan biosynthesis on glycoproteins. However, the dynamic expression and regulation of poFUT1 on the uterine angiogenesis and vascular remodeling remain unknown. Here, we showed that the enlargement of the vascular lumen in the secretory phase was greater than that in the proliferative phase of the uterine endometrium during menstrual cycle; whereas there was a narrower vessel lumen and fewer blood vessels in the decidua from miscarriage patients than in that from healthy pregnancy women. Additionally, the expression of poFUT1 was increased in the uterine endometrium during the secretory phase compared with that in the proliferation phase, and its expression was decreased in the uterus of miscarriage patients compared with that of the healthy pregnancy women. Using hESCs and a mouse model, we demonstrated that poFUT1 increased the O-fucosylation on uPA, and activated of the RhoA signaling pathway, thus facilitating uterine angiogenesis and vascular remodeling. We also provide evidence that poFUT1 promotes hESCs angiogenesis by the decreased stemness of hESCs. These findings reveal a new insight into the uterine angiogenesis and vascular remodeling. The study suggests that poFUT1 could be seen as a novel potential diagnostic and therapeutic target for miscarriage.

MicroRNA changes in maternal serum from pregnancies complicated by twin-twin transfusion syndrome: A discovery study

OBJECTIVE

MicroRNAs (miRNAs) are used as biomarkers in cardiovascular disease and cancer. miRNAs are involved in placental development but have not previously been investigated in twin-twin transfusion syndrome (TTTS). Our aim is to explore the miRNA profile of TTTS pregnancies.

METHOD

Initial miRNA profiling was performed using a reverse transcription polymerase chain reaction (RT-PCR) panel on maternal serum samples taken from five women prior to fetoscopic laser ablation for TTTS and compared with serum samples from five women with uncomplicated monochorionic diamniotic twin pregnancies. Validation RT-PCR was performed in an additional cohort of eight TTTS pregnancies and eight uncomplicated pregnancies.

RESULTS

Median gestational age at sampling in the TTTS and control groups was 20+0  weeks (interquartile range [IQR], 19+4 -20+0 ) and 20+2  weeks (IQR, 20+0 -20+2 ), respectively. All samples passed quality control. One control sample was excluded as a biological outlier. Thirty-one of 752 miRNAs were significantly different: 17 were upregulated and 14 downregulated in the TTTS group, although they did not remain significant following Benjamini-Hochberg correction for multiple testing. The six miRNAs chosen for validation demonstrated no significant difference.

CONCLUSION

This is the first study to investigate miRNA changes in TTTS pregnancies. We did not demonstrate a statistically significant difference in miRNAs in TTTS pregnancies, but further investigation is required.

The Role of Epigenetics in Placental Development and the Etiology of Preeclampsia

In this review, we comprehensively present the function of epigenetic regulations in normal placental development as well as in a prominent disease of placental origin, preeclampsia (PE). We describe current progress concerning the impact of DNA methylation, non-coding RNA (with a special emphasis on long non-coding RNA (lncRNA) and microRNA (miRNA)) and more marginally histone post-translational modifications, in the processes leading to normal and abnormal placental function. We also explore the potential use of epigenetic marks circulating in the maternal blood flow as putative biomarkers able to prognosticate the onset of PE, as well as classifying it according to its severity. The correlation between epigenetic marks and impacts on gene expression is systematically evaluated for the different epigenetic marks analyzed.

miR-196b inhibits cell migration and invasion through targeting MAP3K1 in hydatidiform mole

MicroRNAs (miRNAs) are a class of small non-coding RNAs that are closely associated with carcinogenesis. Accumulating data indicate that miR-196b participates in the development of various types of cancers. However, the role of miR-196b in the formation of hydatidiform mole (HM) is still unclear. Our previous studies have demonstrated that miR-196b levels were decreased in JAR and BeWo cells and in HM tissue samples, as demonstrated by RT-PCR analysis. Furthermore, we discovered that overexpression of miR-196b in JAR and BeWo cells inhibited cellular proliferation, migration and invasion, as shown by Cell counting kit-8 (CCK-8) and transwell assays, respectively. Subsequently, we explored the interaction of miR-196b with its target gene in human choriocarcinoma cell lines. MAP3K1 is a target gene predicted by bioinformatic analysis that was previously shown to exhibit reduced expression levels following treatment with miR-196b in JAR and BeWo cells. We demonstrated that MAP3K1 was a direct target of miR-196b using the dual-luciferase reporter assay in Hela cells. In summary, the present study demonstrated that miR-196b suppressed proliferation, migration and invasion of human choriocarcinoma cells by inhibiting its transcriptional target MAP3K1. miR-196b and MAP3K1 may be considered potential targets for the clinical treatment of HM.

Lipoxin A4 interferes with embryo implantation via suppression of epithelial-mesenchymal transition

PROBLEM

To test whether lipoxin A4 (LXA4) interferes with embryo implantation via suppression of epithelial-mesenchymal transition (EMT).

METHOD OF STUDY

We developed a mouse model of LXA4 blocking embryo implantation and detected the indicators of EMT to confirm that LXA4 inhibits EMT might be a mechanism of interfering with the embryo implantation. We detected integrin-linked kinase (ILK), N-formylpeptide receptor 2 (FPR2), vascular endothelial growth factor, matrix metalloproteinases (MMPs), Akt, GSK3β, NF-ĸB, twist, vimentin, fibronectin, and β-catenin mRNA expression using reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time RT-PCR; localized protein expression using immunohistochemistry and Western blotting assay; MMPs activity assay by gelatin zymography; and the status of implantation in pregnant animals assessed by pontamine blue reaction test.

RESULTS

Preimplantation administration of LXA4 resulted in implantation failure. LXA4 has a time- and dose-dependent effect on embryo implantation. Day 0.5 after fertilization is the most effective time to use LXA4 to block embryo implantation. (a) LXA4 reduced endometrial stroma edema; (b) LXA4 inhibited the activity of MMP9 and significantly upregulated the expression of β-catenin, and downregulated the expression of vimentin, fibronectin, twist, NF-κB, Akt, and Gsk-3β in the endometrium and TEV-1 cells; (c) LXA4 upregulated the expression of FPR2, and downregulated the expression of ILK; FPR2-overexpressing had an inhibitory effect on ILK in TEV-1 cells.

CONCLUSION

LXA4 inhibits EMT which attenuates ILK action by enhancing FPR2; therefore, this might be a mechanism of interfering with embryo implantation.

Imprinted MicroRNA Gene Clusters in the Evolution, Development, and Functions of Mammalian Placenta

In mammals, the expression of a subset of microRNA (miRNA) genes is governed by genomic imprinting, an epigenetic mechanism that confers monoallelic expression in a parent-of-origin manner. Three evolutionarily distinct genomic intervals contain the vast majority of imprinted miRNA genes: the rodent-specific, paternally expressed C2MC located in intron 10 of the Sfmbt2 gene, the primate-specific, paternally expressed C19MC positioned at human Chr.19q13.4 and the eutherian-specific, maternally expressed miRNAs embedded within the imprinted Dlk1-Dio3 domains at human 14q32 (also named C14MC in humans). Interestingly, these imprinted miRNA genes form large clusters composed of many related gene copies that are co-expressed with a marked, or even exclusive, localization in the placenta. Here, we summarize our knowledge on the evolutionary, molecular, and physiological relevance of these epigenetically-regulated, recently-evolved miRNAs, by focusing on their roles in placentation and possibly also in pregnancy diseases (e.g., preeclampsia, intrauterine growth restriction, preterm birth).

Silencing H19 regulated proliferation, invasion, and autophagy in the placenta by targeting miR-18a-5p

Fetal growth restriction (FGR) is a serious pregnancy complication associated with increased perinatal mortality and morbidity. It may lead to neurodevelopmental impairment and adulthood onset disorders. Recently, long noncoding RNAs (lncRNAs) were found to be associated with the pathogenesis of FGR. Here we report that the lncRNAH19 is significantly decreased in placentae from pregnancies with FGR. Downregulation of H19 leads to reduced proliferation and invasion of extravillous trophoblast cells. This is identified with reduced trophoblast invasion, which has been discovered in FGR. Autophagy is exaggerated in FGR. Downregulation of H19 promotes autophagy via the PI3K/AKT/mTOR and MAPK/ERK/mTOR pathways of extravillous trophoblast cells in FGR. We also found that the expression level of microRNAs miR-18a-5p was negatively correlated with that of H19. H19 can act as an endogenous sponge by directly binding to miR-18a-5p, which targets IRF2. The expression of miR-18a-5p was upregulated, but IRF2 expression was downregulated after the H19 knockdown. In conclusion, our study revealed that H19 downexpressed could inhibit proliferation and invasion, and promote autophagy by targeting miR-18a-5pin HTR8 and JEG3 cells. We propose that aberrant regulation of H19/miR-18a-5p-mediated regulatory pathway may contribute to the molecular mechanism of FGR. We indicated that H19 may be a potential predictive, diagnostic, and therapeutic modality for FGR.

Exploring maternal serum microRNAs during early pregnancy in cattle

Confirmation of the pregnancy establishment at the very earliest day post-insemination increases the reproduction efficiency of high yielding dairy cows and farm profitability by allowing rebreeding of the non-pregnant cows. Inaccuracies in the currently available pregnancy detection tools to detect pregnancy establishment within the first 3 weeks post insemination extends the inter-calving interval and have contributed to the decline in profitability. Thus, development of non-invasive early pregnancy detection biomarkers could be proposed as alternative tools. MicroRNAs (miRNAs), a subclass of small non-coding RNAs are abundantly expressed in virtually all bio fluids circulation and have been associated with various pregnancy-related pathophysiological conditions. The study aimed to determine the expression of circulatory miRNAs in serum samples of pregnant and non-pregnant cows at day 19 and 24 post-insemination. Lactating Holstein-Friesian cows were estrous synchronized and inseminated with frozen semen. Blood samples were taken 19 and 24 days post-insemination. Serum samples were retrospectively categorized according to the pregnancy status of cows diagnosed 35 later using ultrasonography. Total RNA enriched with miRNAs was isolated from pooled (4 animals/pool) serum samples of pregnant and non-pregnant cows and subjected to cDNA synthesis. The expression of circulatory miRNAs was performed using PCR array containing primers 748 mature miRNAs. Results showed that a total of 302 and 316 miRNAs were detected in day 19 pregnant and non-pregnant cows, respectively. Similarly, 356 and 325 miRNAs were detected in day 24 pregnant and non-pregnant cows, respectively. Principal component analysis showed clear separation between pregnant and non-pregnant cows both at 19 and 24 days. We identified 8 and 23 differentially expressed miRNAs in the serum of pregnant cows of day 19 and 24, respectively. Interestingly, miR-433 and 4 other miRNAs (miR-487b, miR-495-3p, miR-376b-3p, and miR-323a-3p), which are homologous to the human pregnancy-associated C14MC miRNAs were among the differentially expressed miRNAs in day 19 and 24 pregnant cows, respectively. The adherens junction and ECM-interaction are among the pathways significantly enriched by predicted target genes of differentially expressed miRNAs. In conclusion, the expression of circulatory miRNAs in maternal blood serum of pregnant and non-pregnant cows showed distinct expression pattern and could suggest their potential involvement in early pregnancy establishment.

MicroRNA-218-5p Promotes Endovascular Trophoblast Differentiation and Spiral Artery Remodeling

Preeclampsia (PE) is the leading cause of maternal and neonatal morbidity and mortality. Defects in trophoblast invasion, differentiation of endovascular extravillous trophoblasts (enEVTs), and spiral artery remodeling are key factors in PE development. There are no markers clinically available to predict PE, leaving expedited delivery as the only effective therapy. Dysregulation of miRNA in clinical tissues and maternal circulation have opened a new avenue for biomarker discovery. In this study, we investigated the role of miR-218-5p in PE development. miR-218-5p was highly expressed in EVTs and significantly downregulated in PE placentas. Using first-trimester trophoblast cell lines and human placental explants, we found that miR-218-5p overexpression promoted, whereas anti-miR-218-5p suppressed, trophoblast invasion, EVT outgrowth, and enEVT differentiation. Furthermore, miR-218-5p accelerated spiral artery remodeling in a decidua-placenta co-culture. The effect of miR-218-5p was mediated by the suppression of transforming growth factor (TGF)-β2 signaling. Silencing of TGFB2 mimicked, whereas treatment with TGF-β2 partially reversed, the effects of miR-218-5p. Taken together, these findings demonstrate that miR-218-5p promotes trophoblast invasion and enEVT differentiation through a novel miR-218-5p-TGF-β2 pathway. This study elucidates the role of an miRNA in enEVT differentiation and spiral artery remodeling and suggests that downregulation of miR-218-5p contributes to PE development.

XCL1-XCR1 pathway promotes trophoblast invasion at maternal-fetal interface by inducing MMP-2/MMP-9 activity

PROBLEM

Certain chemokines with their receptors can promote or inhibit trophoblast cell migration and invasion in human first-trimester placenta. Whether the lymphotactin (Lptn; XCL1)-XC chemokine receptor 1 (XCR1) chemokine pathway affects trophoblast cell migration and invasion in human first-trimester placenta remains unclear.

METHOD OF STUDY

The expression pattern of chemokine XCL1 and its receptor XCR1 was detected in human first-trimester by qRT-PCR, and the effect of recombinant human XCL1 (rhXCL1) on trophoblast cell function was tested by wound healing and Transwell assays. Matrix metalloproteinase (MMP) activity in trophoblast cells treated with rhXCL1 was assessed via qRT-PCR and gelatin zymography.

RESULTS

Abundant XCR1 mRNA was expressed in the first-trimester decidua and villi. XCL1 and XCR1 mRNA were expressed at a higher level in the first-trimester than in the term placenta. RhXCL1 promoted trophoblast cell migration and invasion by increasing MMP-9 and MMP-2 activity and that of the MMP-2/tissue inhibitor of metalloproteinases 2 (TIMP-2) complex via the phosphatidylinositol 3-kinase (PI3K)/AKT kinase (AKT), mitogen-activated protein kinase (MEK), and JUN N-terminal kinase (JNK) signaling pathways.

CONCLUSION

XCL1-XCR1 chemokine pathway promotes trophoblast invasion by increasing matrix metalloproteinase activity in human first-trimester placenta.

Forskolin-mediated BeWo cell fusion involves down-regulation of miR-92a-1-5p that targets dysferlin and protein kinase cAMP-activated catalytic subunit alpha

PROBLEM

To study the role of miRNA(s) during trophoblastic BeWo cell fusion.

METHOD OF STUDY

Changes in miRNA(s) profile of BeWo cells treated with forskolin were analyzed using Affymetrix miRNA microarray platform. Down-regulated miRNA, miR-92a-1-5p, was overexpressed in BeWo cells followed by forskolin treatment to understand its relevance in the process of BeWo cell fusion by desmoplakin I+II staining and hCG secretion by ELISA. Predicted targets of miR-92a-1-5p were also confirmed by qRT-PCR/Western blotting.

RESULTS

The miRNA profiling of BeWo cells after forskolin (25 μmol/L) treatment identified miR-92a-1-5p as the most significantly down-regulated miRNA both at 24 and 48 hours time points. Overexpression of miR-92a-1-5p in these cells led to a significant decrease in forskolin-mediated cell fusion and hCG secretion. miRNA target prediction software, TargetScan, revealed dysferlin (DYSF) and protein kinase cAMP-activated catalytic subunit alpha (PRKACA), as target genes of miR-92a-1-5p. Overexpression of miR-92a-1-5p in BeWo cells showed reduction in forskolin-induced transcripts for DYSF and PRKACA. Further, reduction in DYSF (~2.6-fold) at protein level and PRKACA-encoded protein kinase A catalytic subunit alpha (PKAC-α; ~1.6-fold) were also observed.

CONCLUSION

These observations suggest that miR-92a-1-5p regulates forskolin-mediated BeWo cell fusion and hCG secretion by regulating PKA signaling pathway and dysferlin expression.

H19 long noncoding RNA alters trophoblast cell migration and invasion by regulating TβR3 in placentae with fetal growth restriction

Fetal growth restriction (FGR) is a well-recognized risk factor for perinatal mortality and morbidity, as well as neurodevelopmental impairment and adulthood onset disorders. Here we report that the H19 long noncoding RNA (lncRNA) is significantly decreased in placentae from pregnancies with FGR. Downregulation of H19 leads to reduced migration and invasion of extravillous trophoblast (EVT) cells in vitro. This is consistent with reduced trophoblast invasion that has been observed in FGR. Genome-scale transcriptome profiling of EVT cells reveals significantly decreased expression of the type III TGF-β receptor (TβR3) following H19 knockdown. Decreased TβR3 expression is also seen in FGR placentae. TβR3 repression decreases EVT cell migration and invasion, owing to impaired TGF-β signaling through a non-canonical TGF-β signaling pathway. Further, we identify TβR3 as a novel regulatory target of microRNA let-7. We propose that dysregulation of this newly identified H19/TβR3-mediated regulatory pathway may contribute to the molecular mechanism of FGR. Our findings are the first to show a lncRNA-based mechanism of FGR, holding promise for the development of novel predictive, diagnostic, and therapeutic modalities for FGR.

[New perspectives on preeclampsia]

Preeclampsia is a major, frequent and potentially severe condition of pregnancy, characterized by severe hypertension and proteinuria. In this review, we describe recent advances in understanding the pathology, and discuss the long-term impacts on maternal vascular health. Next, we describe the genetic, epigenetic and immunological basis of preeclampsia. We describe the links between preeclampsia and oxidative stress in placental (trophoblast) and endothelial cells. We mention cellular and animal models commonly used to decipher modified pathophysiological pathways in a preeclamptic pregnancy compared to a normal pregnancy. Finally, we discuss the therapeutic options, readily available or in development, to improve the monitoring of pregnancies, the health of patients and that of children born from preeclamptic pregnancies.

Circulating levels of specific members of chromosome 19 microRNA cluster are associated with preeclampsia development

PURPOSE

To perform serum microRNA expression profiling to identify members of chromosome 19 miRNA cluster involved in preeclampsia development.

METHODS

Serum chromosome 19 miRNA cluster microRNA expression profiling was evaluated at 12, 16, and 20 gestational weeks and at the time of preeclampsia diagnosis, in women who developed preeclampsia (WWD-PE; n = 16) and controls (n = 18) using TaqMan low density array plates.

RESULTS

A total of 51 chromosome 19 microRNA cluster members were evaluated. The circulating hsa-miRs 512-3p, 518f-3p, 520c-3p, and 520d-3p, were differentially expressed between groups (P < 0.05). Compared with controls, serum levels of hsa-miR-518f-3p at 20 GW were useful for identifying WWD-Mild-PE (P = 0.035) and WWD-Severe-PE (P = 0.007).

CONCLUSIONS

Serum hsa-miRs 512-3p, 518f-3p, 520c-3p, and 520d-3p, are differentially expressed between WWD-PE and controls and their role in the development of preeclampsia should be investigated further.

Placental trophoblast debris mediated feto-maternal signalling via small RNA delivery: implications for preeclampsia

To profile the small RNA cargo carried by trophoblast debris derived from the placenta during normal and preeclamptic pregnancies and to determine whether trophoblast debris can deliver its small RNAs to endothelial cells with functional consequences. We confirmed that trophoblast debris can deliver its small RNAs contents to recipient endothelial cells during the co-culture. Next generation sequencing was employed to profile the small RNA contents in both normotensive and preeclamptic trophoblast debris. We identified 1278 mature miRNAs and 2646 non-miRNA small RNA fragments contained. Differential expression analysis identified 16 miRNAs (including miR-145), 5 tRNA fragments from 3 different tRNAs, 13 snRNA fragments and 85 rRNA fragments that were present in different levels between preeclamptic and normotensive trophoblast debris. We loaded a miR-145 mimic into normotensive trophoblast debris via transfection of placental explants from which the debris was derived and found the miR-145 loaded debris induced transcriptomic changes in endothelial cells similar to those induced by preeclamptic trophoblast debris. Trophoblast debris deported into maternal circulation can deliver its small RNA contents to maternal cells thereby contributing to feto-maternal communication. Small RNAs that are dysregulated in preeclamptic trophoblast debris might contribute to the endothelial cell activation which is a hallmark of preeclampsia.

Low levels of exosomal-miRNAs in maternal blood are associated with early pregnancy loss in cloned cattle

Nuclear reprogramming mediated by somatic cell nuclear transfer (SCNT) has many applications in medicine. However, animal clones show increased rates of abortion and reduced neonatal viability. Herein, we used exosomal-miRNA profiles as a non-invasive biomarker to identify pathological pregnancies. MiRNAs play important roles in cellular proliferation and differentiation during early mammalian development. Thus, the aim of this study was to identify exosomal-miRNAs in maternal blood at 21 days of gestation that could be used for diagnosis and prognosis during early clone pregnancies in cattle. Out of 40 bovine-specific miRNAs, 27 (67.5%) were with low abundance in the C-EPL (Clone - Early pregnancy loss) group compared with the C-LTP (Clone - Late pregnancy) and AI-LTP (Artificial Insemination - Late pregnancy) groups, which had similar miRNAs levels. Bioinformatics analysis of the predicted target genes demonstrated signaling pathways and functional annotation clusters associated with critical biological processes including cell proliferation, differentiation, apoptosis, angiogenesis and embryonic development. In conclusion, our results demonstrate decreased exosomal-miRNAs in maternal blood at 21 days of gestation in cloned cattle pregnancies that failed to reach term. Furthermore, the predicted target genes regulated by these 27 miRNAs are strongly associated with pregnancy establishment and in utero embryonic development.

Efficient production of trophoblast lineage cells from human induced pluripotent stem cells

Human induced pluripotent stem cells (hiPSCs) are potentially useful in both clinical applications and basic biological research. hiPSCs can differentiate into extra-embryonic cells in the presence of BMP4. However, the differentiation potential of hiPSCs can be affected by culture conditions or genetic variation. In this study, we investigated the effect of various BMP4 concentrations on the expression states of trophoblast markers and the optimal conditions for trophoblast induction. A high-fidelity gene expression assay using hiPSC lines showed that the expression levels of various trophoblast marker genes, such as KRT7, GCM1, CGB, and HLA-G, were upregulated by BMP4 in a dose-dependent manner in all types of hiPSCs used in this study. Treatment with high doses of BMP4 for prolonged periods increased the ratio of cells with trophoblast markers irrespective of the presence of bFGF. We found that the expression states of major pluripotency- and differentiation-related protein-coding genes in BMP4-treated cells depended on culture conditions rather than donor cell types. However, miRNA expression states were affected by donor cell types rather than BMP4 dose. Furthermore, the effect of the presence of bFGF on differentiation potential of KRT7-positive cells differed among iPSC types. Mechanistically, chromatin states around KRT7 promoter regions were comparable among the iPSC types used in this study, indicating that hiPSC chromatin state at these regions is not a parameter for cytotrophoblast differentiation potential. In conclusion, the optimal conditions for trophoblast differentiation from hiPSCs differ according to parental cell line.

miR-346 and miR-582-3p-regulated EG-VEGF expression and trophoblast invasion via matrix metalloproteinases 2 and 9

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) is an important regulator for embryo implantation and placental development, and is clinically associated with several obstetric disorders related to insufficient or inappropriate trophoblast invasion, such as recurrent abortion, preeclampsia, and intrauterine fetal growth restriction. This study was performed to identify the microRNAs targeting EG-VEGF, and evaluate the regulatory effect on trophoblast biology. miR-346 and miR-582-3p were initially identified via bioinformatic tools, and their specific binding sites on the EG-VEGF 3'UTR were further confirmed using dual luciferase and a co-transfection assays. miR-346 and miR-582-3p were demonstrated not only to suppress EG-VEGF expression, but also inhibit trophoblast invasion and migration in the JAR and HTR-8/SVneo cell lines. We further evaluated the effect of microRNAs in HTR-8/SVneo cells coexpressing EG-VEGF and miR-346 or miR-582-3p on matrix metalloproteinase (MMP 2 and MMP 9) and the tissue inhibitors of metalloproteinase (TIMP 1 and TIMP 2) using RT-PCR, western blotting and gelatin zymography. TIMP 1 and TIMP 2 were not affected by the two microRNAs, whereas the expressions and activities of MMP 2 and MMP 9 were significantly downregulated, which in turn inhibited the invasion ability of trophoblasts. In conclusion, miR-346 and miR-582-3p regulate EG-VEGF-induced trophoblast invasion through repressing MMP 2 and MMP 9, and may become novel diagnostic biomarkers or therapeutic targets for EG-VEGF-related obstetric disorders. © 2016 BioFactors, 43(2):210-219, 2017.

The YY1/MMP2 axis promotes trophoblast invasion at the maternal-fetal interface

YY1 is a sequence-specific DNA-binding transcription factor that has many important biological roles. However, its function in trophoblasts at the maternal-fetal interface remains to be elucidated. In this study, we used an mRNA microarray and reverse transcription qPCR and compared the YY1 mRNA expression level in trophoblasts between patients with recurrent miscarriage (RM) and healthy control subjects. Our results revealed that YY1 mRNA expression was significantly lower in the trophoblasts of the RM group compared with the healthy control group. Furthermore, immunofluorescence and immunohistochemical data showed that YY1 was highly expressed in human placental villi during early pregnancy, especially in cytotrophoblast cells and invasive extravillous trophoblasts, and it was expressed at a much lower level in the placental villi of term pregnancy. YY1 overexpression enhanced, and knockdown repressed, the invasion and proliferation of trophoblasts. Antibody array screening revealed that YY1 significantly promoted MMP2 expression in trophoblasts. Bioinformatics analysis identified three YY1-binding sites in the MMP2 promoter region, and chromatin immunoprecipitation analysis verified that YY1 binds directly to its promoter region. Importantly, inhibition of YY1 by siRNA clearly decreased trophoblast invasion in an ex vivo explant culture model. Overall, our findings revealed a new regulatory pathway of YY1/MMP2 in trophoblast cell invasion during early pregnancy and indicated that YY1 may be involved in the pathogenesis of RM.

Circulating miRNA signatures of early pregnancy in cattle

Background

Low fertility remains a leading cause of poor productivity in dairy cattle. In this context, there is significant interest in developing novel tools for accurate early diagnosis of pregnancy. MicroRNAs (miRNAs) are short RNA molecules which are critically involved in regulating gene expression during both health and disease. MiRNAs have been shown to regulate ovarian function, uterine receptivity, embryonic development and placental function. Circulating miRNAs can provide useful biomarkers of tissue function and disease; importantly, differential miRNA profiles have been linked to pregnancy and preeclampsia in humans. This study sought to establish the potential of circulating miRNAs as biomarkers of early pregnancy in cattle.

Results

We applied Illumina small-RNA sequencing to profile miRNAs in plasma samples collected from eight non-pregnant heifers on Days 0, 8 and 16 of the oestrous cycle and 11 heifers on Days 16 and 24 of pregnancy. We sequenced a total of 46 samples and generated 9.2 million miRNA reads per sample. There were no differences in miRNA read abundance between any of the pregnant and non-pregnant time-points (FDR > 0.1). As a complementary approach, we analysed sample pools (3–4 samples/pool) corresponding to Days 0, 8 and 16 of the oestrous cycle and Day 24 of pregnancy (n = 3 pools/group) using Qiagen PCR arrays. A total of 16 miRNAs were differentially expressed (FDR < 0.1) in plasma between pregnant and non-pregnant animals. RT-qPCR validation using the same plasma samples confirmed that miR-26a was differentially upregulated on Day 16 pregnant relative to non-pregnant heifers (1.7-fold; P = 0.043), whereas miR-1249 tended to be upregulated in Day 16 pregnant heifers (1.6-fold; P = 0.081). Further validation in an independent group of heifers confirmed an increase in plasma miR-26a levels during early pregnancy, which was significant only on Day 24 (2.0-fold; P = 0.027).

Conclusions

Through genome-wide analyses we have successfully profiled plasma miRNA populations associated with early pregnancy in cattle. We have identified miR-26a as a potential circulating biomarker of early pregnancy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2529-1) contains supplementary material, which is available to authorized users.

MicroRNA-34a inhibits human trophoblast cell invasion by targeting MYC

Background

Preeclampsia, one of the major disorders of pregnancy, is characterized by inadequate trophoblast invasion and defective trophoblast-mediated remodeling of placental vasculature. MicroRNA-34a (miR-34a) has been found to be aberrantly expressed in the placentas of preeclamptic patients, yet its role in placental development and in the pathogenesis of preeclampsia remains elusive.

Results

The levels of miR-34a in the placentas of 20 preeclamptic patients and 20 healthy subjects were determined by real time-PCR, and miR-34a was found significantly elevated in the preeclamptic placentas. Further, the function of miR-34a in trophoblast cells was investigated by overexpressing miR-34a in JEG-3 trophoblast cell line. Overexpression of miR-34a in JEG-3 cells inhibited cell proliferation, migration and invasion. In addition, elevated expression of miR-34a reduced the expression of both endogenous and ectopic MYC. Moreover, we identified that MYC mRNA was a direct target of miR-34a in JEG-3 cells by dual luciferase reporter assay, and found that downregulation of MYC expression by miR-34a targeting significantly reduced the invasiveness of JEG-3 cells.

Conclusions

Our findings provide preliminary evidence for the diverse functions of miR-34a in trophoblast biology, and suggest that miR-34a suppresses trophoblast invasion by directly targeting MYC.

HCG-Activated Human Peripheral Blood Mononuclear Cells (PBMC) Promote Trophoblast Cell Invasion

Successful embryo implantation and placentation depend on appropriate trophoblast invasion into the maternal endometrial stroma. Human chorionic gonadotropin (hCG) is one of the earliest embryo-derived secreted signals in the peripheral blood mononuclear cells (PBMC) that abundantly expresses hCG receptors. The aims of this study were to estimate the effect of human embryo-secreted hCG on PBMC function and investigate the role and underlying mechanisms of activated PBMC in trophoblast invasion. Blood samples were collected from women undergoing benign gynecological surgery during the mid-secretory phase. PBMC were isolated and stimulated with or without hCG for 0 or 24 h. Interleukin-1β (IL-1β) and leukemia inhibitory factor (LIF) expressions in PBMC were detected by enzyme-linked immunosorbent assay and real-time polymerase chain reaction (PCR). The JAR cell line served as a model for trophoblast cells and was divided into four groups: control, hCG only, PBMC only, and PBMC with hCG. JAR cell invasive and proliferative abilities were detected by trans-well and CCK8 assays and matrix metalloproteinase (MMP)-2 (MMP-2), MMP-9, vascular endothelial growth factor (VEGF), tissue inhibitor of metalloproteinase (TIMP)-1, and TIMP-2 expressions in JAR cells were detected by western blotting and real-time PCR analysis. We found that hCG can remarkably promote IL-1β and LIF promotion in PBMC after 24-h culture. PBMC activated by hCG significantly increased the number of invasive JAR cells in an invasion assay without affecting proliferation, and hCG-activated PBMC significantly increased MMP-2, MMP-9, and VEGF and decreased TIMP-1 and TIMP-2 expressions in JAR cells in a dose-dependent manner. This study demonstrated that hCG stimulates cytokine secretion in human PBMC and could stimulate trophoblast invasion.

The Function of TrophomiRs and Other MicroRNAs in the Human Placenta

In eutherian organisms, the placenta interfaces the fetal and maternal environments. Located at the placental villous surface, in direct contact with maternal blood, is the trophoblast layer, which mediates the crucial maternal-fetal exchange of gases, nutrients, and waste products, produces hormones that support the pregnancy, and provides immunologic defense. Discovery of microRNAs (miRNAs) and their role in development, differentiation, and homeostatic resilience has increased our understanding of genomic and epigenomic networks that regulate placental function. Moreover, unique miRNA species, which are expressed by human trophoblasts and are termed "trophomiRs," may show specialized functions during normal and pathological pregnancies. Placental miRNAs, packaged within exosomes and other vesicles or bound in protein complexes, are capable of communicating distinctive signals to maternal and/or fetal tissues. Additional research may usher in the use of circulating miRNAs as pregnancy-related disease biomarkers, providing new diagnostic and therapeutic options during pregnancy.

Galectins in angiogenesis: consequences for gestation

Members of the galectin family have been shown to exert several roles in the context of reproduction. They contribute to placentation, maternal immune regulation and facilitate angiogenesis encompassing decidualisation and placenta formation during pregnancy. In the context of neo-vascularisation, galectins have been shown to augment signalling pathways that lead to endothelial cell activation, cell proliferation, migration and tube formation in vitro in addition to angiogenesis in vivo. Angiogenesis during gestation ensures not only proper foetal growth and development, but also maternal health. Consequently, restriction of placental blood flow has major consequences for both foetus and mother, leading to pregnancy diseases. In this review we summarise both the established and the emerging roles of galectin in angiogenesis and discuss the possible implications during healthy and pathological gestation.

C19MC microRNAs regulate the migration of human trophoblasts

Early in pregnancy, trophoblast invasion into the decidua and inner myometrium is essential for establishment of proper implantation, maternal-fetal exchange, and immunological tolerance of the feto-placental allograft. Unlike villous trophoblasts (VTs), extravillous trophoblasts (EVTs) are unique in their capacity to invade the maternal decidua and myometrium. The largest human microRNA (miRNA) gene cluster, the chromosome 19 miRNA cluster (C19MC), is expressed almost exclusively in the placenta and, rarely, in certain tumors and undifferentiated cells. In the work reported here, we found that the expression of C19MC miRNAs is higher in VTs than in EVTs. Using a bacterial artificial chromosome (BAC)-mediated overexpression of C19MC miRNAs in an EVT-derived cell line, which does not naturally express these miRNAs, we found that C19MC miRNAs selectively attenuate cell migration without affecting cell proliferation or apoptosis. A microarray analysis revealed that C19MC miRNAs regulate target transcripts related to cellular movement. Our data also implicated a specific C19MC member, miR-519d, indirectly regulating the EVT invasive phenotype by targeting CXCL6, NR4A2 and FOXL2 transcripts through a 3'UTR miRNA-responsive element. Together, our data suggest a role for C19MC miRNAs in modulating the migration of EVTs.

miR455 is linked to hypoxia signaling and is deregulated in preeclampsia

Preeclampsia is a severe pregnancy-related disorder and a leading cause of maternal and fetal mortality worldwide. Early identification of patients with an increased risk for preeclampsia is thus one of the most important goals in obstetrics. Here we identify two related human microRNAs as potential biomarkers to detect at-risk pregnancies. We demonstrate that miR455-3P and miR455-5P are significantly downregulated in placentas from preeclampsia patients, whereas other placenta-specific microRNAs remain unaffected. microRNA target prediction and validation revealed a potential link of miR455-3P to hypoxia signaling. Together with our observation that expression levels of miR455-3P and miR455-5P are upregulated during trophoblast differentiation, our results suggest a model in which miR455-3P represses a hypoxia response that might otherwise prevent cytotrophoblasts from syncytiotrophoblast differentiation. In summary, our work reveals aberrant hypoxia signaling in preeclampsia that can be explained by deregulated expression of miR455. As miR455 has been found in circulating blood, the development of noninvasive prenatal tests enabling early diagnosis of preeclampsia may be possible.