Governing the invasive trophoblast: current aspects on intra- and extracellular regulation

The role of circular RNA in preeclampsia: From pathophysiological mechanism to clinical application

Preeclampsia (PE) is a common pregnancy-induced hypertension disorder that poses a significant threat to the health of pregnant women and fetuses, and has become a leading cause of maternal, fetal, and neonatal mortality. Currently, the therapy strategy for PE is mainly prevention management and symptomatic treatment, and only delivery can completely terminate PE. Therefore, a deeper understanding of the pathogenesis of PE is needed to make treatment and prevention more effective and targeted. With the deepening of molecular etiology research, circular RNAs (circRNAs) have been found to be widely involved in various processes of PE pathogenesis. As a kind of RNA with a special "head to tail" loop structure, the characteristics of circRNAs enable them to play diverse roles in the pathophysiology of PE, and can also serve as ideal biomarkers for early prediction and monitoring progression of PE. In this review, we summarized the latest research on PE-related circRNAs, trying to elucidate the unique or shared roles of circRNAs in various pathophysiological mechanisms of PE, aiming to provide a whole picture of current research on PE-related circRNAs, and extend a new perspective for the precise screening and targeted therapy of PE.

miR‑424‑5p is downregulated in the placentas of patients with preeclampsia and affects trophoblast migration and invasion

Insufficient invasion of trophoblast cells has been reported to be closely associated with the pathogenesis of preeclampsia (PE). MicroRNAs (miRs) have essential roles in the trophoblasts invasion via targeting specific genes with diverse functions. However, the underlying mechanism remains largely unclear and requires further investigation. The present study aimed to identify and evaluate the potential functions of miRs in trophoblasts invasion and to reveal the underlying mechanisms. In the present study, differentially expressed miRs that were screened based on previously published microarray data (GSE96985) and a significantly downregulated miR-424-5p (miR-424) was chosen for further investigation. Subsequently, reverse transcription-quantitative PCR, CCK-8, apoptosis, wound healing and Transwell assays were performed to determine the cell viability, apoptotic rate, cell migration and invasion of trophoblast cells. The results showed that miR-424 was decreased in placenta specimens from patients with PE. Upregulation of miR-424 promoted cell viability, suppressed cell apoptosis and improved the invasion and migration of trophoblasts, whereas inhibition of miR-424 had opposite results. Adenomatous polyposis coli (APC), a key mediator of Wnt/β-catenin signaling pathway, was identified as a functional target of miR-424 and an inverse relationship was observed between APC and miR-424 in placenta specimens. Further investigations revealed that APC overexpression efficiently suppressed the effect of miR-424 in trophoblast cells. In addition, the miR-424-mediated effects on trophoblast cells were dependent on the promotion of Wnt/β-catenin signaling pathway. The present findings revealed that miR-424 regulates the trophoblast cell invasion by regulating Wnt/β-catenin pathway through targeting APC, indicating miR-424 as a potential candidate for the treatment of PE.

Folic Acid Levels During Pregnancy Regulate Trophoblast Invasive Behavior and the Possible Development of Preeclampsia

Background

One of the unique features of placentation is its similarity to tumorigenesis yet being very well regulated. It allows rapid proliferation, migration, and invasion of mononuclear trophoblast cells into the maternal uterus and remodeling the maternal vasculature. This pseudomalignant nature of trophoblastic cells is strictly regulated and its importance becomes evident in abnormal pregnancies that are characterized by aberrant trophoblast proliferation/invasion like preeclampsia. In addition to this, the importance of folic acid supplementation during pregnancy is well documented. We aimed to analyze the molecular and epigenetic regulation of the pseudomalignant nature of placentation via folic acid levels.

Methods

Placental tissue samples were collected from different pregnancies in three different gestational stages. We estimated the impact of folic acid levels on global methylation, LINE1 methylation, and expression of DNMTs in all three gestational stages in pregnant women and preeclampsia pregnancies. We also analyzed the effect of folic acid supplementation on trophoblastic invasion using placental derived cells viz, JEG-3 and HTR-8/SVneo cell line and verified the molecular and epigenetic mechanisms involved in this regulation.

Results

Development of preeclampsia was observed to be associated with lower folate levels in placental tissue, higher global methylation level, and higher expression of DNMT1and DNMT3A. Folic acid supplementation was found to increase the invasive potential of placental trophoblasts by almost two folds which were associated with the decreased expression of tumor suppressor genes and tissue inhibitors of matrix metalloproteinases; and increased expression of oncogenes, telomerase gene, and matrix metalloproteinases. These folic acid-mediated changes were observed to be regulated by CpG methylation in the case of many genes. Folic acid supplementation was also observed to significantly decrease global methylation in placental trophoblasts related to decreasing expression of DNMT1 and DNMT3A.

Conclusion

Lower folic acid levels are associated with preeclampsia development and folic acid supplementation regulates the invasive potential of placental trophoblasts as mediated by various epigenetic changes in the placenta suggesting the protective effect of folic acid against preeclampsia.

Circular RNAs in Pregnancy and the Placenta

The emerging field of circular RNAs (circRNAs) has identified their novel roles in the development and function of many cancers and inspired the interest of many researchers. circRNAs are also found throughout the healthy body, as well as in other pathological states, but while research into the function and abundance of circRNAs has progressed, our overall understanding of these molecules remains primitive. Importantly, recent studies are elucidating new roles for circRNAs in pregnancy, particularly in the placenta. Given that many of the genes responsible for circRNA production in cancer are also highly expressed in the placenta, it is likely that the same genes act in the production of circRNAs in the placenta. Furthermore, placental development can be referred to as ‘controlled cancer’, as it shares many key signalling pathways and hallmarks with tumour growth and metastasis. Hence, the roles of circRNAs in this field are important to study with respect to pregnancy success but also may provide novel insights for cancer progression. This review illuminates the known roles of circRNAs in pregnancy and the placenta, as well as demonstrating differential placental expressions of circRNAs between complicated and uncomplicated pregnancies.

Matrix Metalloproteinases in Human Decidualized Endometrial Stromal Cells

Cyclic changes, such as growth, decidualization, shedding, and regeneration, in the human endometrium are regulated by the reciprocal action of female hormones, such as estradiol (E₂), and progesterone (P₄). Matrix metalloproteases (MMPs) and tissue inhibitors of MMPs (TIMPs) control the invasion of extravillous trophoblast cells after implantation. Several MMPs and TIMPs function in the decidua and endometrial stromal cells (ESCs). Here, we aimed to systematically investigate the changes in MMPs and TIMPs associated with ESC decidualization. We evaluated the expression of 23 MMPs, four TIMPs, and four anti-sense non-coding RNAs from MMP loci. Primary ESC cultures treated with E₂ + medroxyprogesterone acetate (MPA), a potent P₄ receptor agonist, showed significant down-regulation of MMP3, MMP10, MMP11, MMP12, MMP20, and MMP27 in decidualized ESCs, as assessed by quantitative reverse transcription PCR. Further, MMP15 and MMP19 were significantly upregulated in decidualized ESCs. siRNA-mediated silencing of Heart and Neural Crest Derivatives Expressed 2 (HAND2), a master transcriptional regulator in ESC decidualization, significantly increased MMP15 expression in untreated human ESCs. These results collectively indicate the importance of MMP15 and MMP19 in ESC decidualization and highlight the role of HAND2 in repressing MMP15 transcription, thereby regulating decidualization.

Comparative matrix metalloproteinase-2 and -9 expression and activity during endotheliochorial and hemochorial trophoblastic invasiveness

To establish a functional placenta, its development needs adequate trophoblastic invasiveness. The intricate and complex morphological and molecular aspects regulating trophoblastic invasion during endotheliochorial placentation of domestic carnivores and their similarities and differences with the hemochorial placenta are still poorly understood. During placentation processes, from the time of implantation, trophoblast cells invade the uterine endometrium where they achieve extensive degradation and remodeling of extracellular matrix components; in this process, matrix metalloproteinases (MMPs), particularly MMP-2 and 9, have an essential role in rebuilding, cell migration, and invasiveness. This review provides an overview of comparative trophoblast invasive events and the expression and activity of MMP-2 and 9 during endotheliochorial and hemochorial placentation, emphasizing dog and mouse placental models. Understanding of trophoblastic invasiveness in two models of placentation, the intermediately invasive domestic carnivore endotheliochorial placenta, and the more highly invasive mouse hemochorial placenta, contributes to deepen knowledge of the trophoblast invasive processes and their diverse and complex human placental alterations, such as preeclampsia.

Elevated Serum SFRP5 Levels During Preeclampsia and Its Potential Association with Trophoblast Dysfunction via Wnt/β-Catenin Suppression

Preeclampsia (PE) is a life-threatening pregnancy complication associated with diminished trophoblast migration and invasion. Wnt signalling is one of the most important regulators of placentation. Secreted frizzled-related protein 5 (SFRP5) is an anti-inflammatory adipokine that may inhibit Wnt signalling. In this study, we aimed to investigate the relationship between SFRP5 and PE and its effect on trophoblast function, as well as the underlying signalling pathways. SFRP5 levels in the serum and placental tissues were detected using enzyme-linked immunosorbent assay and immunohistochemistry, respectively. To evaluate the effect of SFRP5 on Wnt signalling, the human trophoblast cell line HTR8/SVneo was treated with recombinant human SFRP5 and Dickkopf-related protein 1 (Dkk-1, canonical Wnt inhibitor) proteins and lithium chloride (LiCl, canonical Wnt agonist). The migration and invasion ability of HTR8/SVneo cells was evaluated using wound-healing and Matrigel Transwell assays. The activities of multiple matrix metalloproteinases (MMP)-2/9 were detected using gelatin zymography. Expression of glycogen synthase kinase-3 beta (GSK3β) and β-catenin proteins was investigated using western blotting. The serum SFRP5 levels were elevated in patients with PE, but SFRP5 expression was not detected in the placental tissues. Furthermore, SFRP5 inhibited the migration and invasion of HTR8/SVneo cells in vitro, increased GSK3β, and decreased β-catenin expression and MMP-2/9 activity in HTR8/SVneo cells. In conclusion, this study suggests that SFRP5 inhibits trophoblast migration and invasion potentially via the inhibition of Wnt/β-catenin signalling, which might be involved in the development of PE. However, the primary cause of the increased SFRP5 levels needs to be investigated.

LncRNA LINC01088 inhibits the function of trophoblast cells, activates the MAPK-signaling pathway and associates with recurrent pregnancy loss

Long noncoding RNAs (lncRNAs) have been reported to be involved in various cellular processes and to participate in a variety of human diseases. Recently, increasing studies have reported that lncRNAs are related to many reproductive diseases, such as pathogenesis of recurrent pregnancy loss (RPL), preeclampsia (PE) and gestational diabetes mellitus (GDM). In this study, we aimed to investigate the effect of LINC01088 in trophoblast cells and its potential role in pathogenesis of RPL. LINC01088 was found to be upregulated in first-trimester chorionic villi tissues from RPL patients. Increased LINC01088 repressed proliferation, migration and invasion of trophoblast cells, and promoted apoptosis of trophoblast cells. Further exploration indicated that LINC01088 decreased the production of nitric oxide (NO) by binding and increasing Arginase-1 and decreasing eNOS protein levels. Importantly, JNK and p38 MAPK-signaling pathways were active after overexpression of LINC01088. In conclusion, our studies demonstrated that LINC01088 plays an important role in the pathogenesis of RPL, and is a potential therapeutic target for the treatment of RPL.

M2 macrophage-derived G-CSF promotes trophoblasts EMT, invasion and migration via activating PI3K/Akt/Erk1/2 pathway to mediate normal pregnancy

Trophoblasts are important parts of the placenta and exert vital roles in the maternal-foetal crosstalk, and sufficient trophoblasts migration and invasion is critical for embryo implantation and normal pregnancy. Macrophages, as the major components of decidual microenvironment at maternal-foetal interface, can interact with trophoblasts to participate in the regulation of normal pregnancy. Previously, our group have demonstrated that trophoblasts could induce macrophages polarization to M2 subtype by secreting interleukin-6 (IL-6); however, the understanding of macrophages regulating the migration and invasion of trophoblasts is limited. In the present study, we used the co-cultured model to further investigate the effects of macrophages on trophoblasts migration and invasion. Our results showed that co-culture with macrophages promoted epithelial-to-mesenchymal transition (EMT) of trophoblasts, thereby enhancing their migrative and invasive abilities. Further experiments revealed that M2 macrophage-derived G-CSF was a key factor, which promoted the EMT, migration and invasion of trophoblasts via activating PI3K/Akt/Erk1/2 signalling pathway. Clinically, G-CSF was highly expressed in placental villous tissues of normal pregnancy patients compared to patients with recurrent spontaneous abortion, and its expression level was significantly correlation with EMT markers. Taken together, these findings indicate the important role of M2 macrophages in regulating trophoblasts EMT, migration and invasion, contributing to a new insight in concerning the crosstalk between macrophages and trophoblasts in the establishment and maintenance of normal pregnancy.

Macrophage migration inhibitory factor modulates cytokine expression in the trophoblast cell line HTR-8/SVneo

Extravillous trophoblasts are specific placental cells that invade the uterine stroma and spiral arteries modifying and adjusting them to pregnancy. Many pregnancy pathologies are associated with impairment of this process, including preeclampsia and intrauterine growth restriction, among others. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that is abundant at the fetomaternal interface. Previous results from our group showed that MIF participates in trophoblast invasion and modulates the expression of molecules known to mediate stromal and endovascular trophoblast invasion. In this study we investigated the possibility that MIF could act as a regulator of cytokines known to modulate trophoblast invasion using the normal extravillous trophoblast-derived cell line HTR-8/SVneo. Expression of trophoblast MIF was attenuated by MIF mRNA-specific small interfering RNAs. Cytokine expression was assessed at the mRNA and protein levels using real-time quantitative polymerase chain reaction and flow cytometry respectively. Knockdown of MIF led to a significant decrease in mRNA for IL-1β (IL1B) and IL-8 (CXCL8) and interleukin (IL)-8 protein. The addition of recombinant human MIF to cell culture medium increased IL-6 after 24h treatment and IL-6 and IL-8 after 72h treatment. Cell viability was not affected by MIF silencing or rhMIF treatment. The results of this study imply that at least some of the effects of MIF on trophoblast invasion could be mediated through autocrine or paracrine modulation of trophoblast cytokine production.

Expression of interleukin-6 (IL-6), signal transducer and activator of transcription-3 (STAT-3) and telomerase in choriocarcinomas

Abstract

Blastocyst implantation and neoplastic invasion have some common properties related to tissue invasion, mediated by various cytokines.

Aim

To compare the expression of IL-6, STAT-3 and telomerase in material of abortions in the first trimester of pregnancy, at term placentas and in choriocarcinomas.

Methods

Immunohistochemical reactions were performed on formalin fixed and included in paraffin samples from 3 groups: abortions, normal at term placentas and choriocarcinomas. Western Blot and Real-Time PCR assays were performed on fresh material from BeWo cell line and in primary culture cells of normal placenta.

Results

Immunohistochemical reactions: IL-6 expression was moderate in the first trimester abortion samples and high in at term placentas and choriocarcinomas. STAT-3 was strongly positive in all groups. Telomerase expression was absent in normal at term placentas but was increased in BeWo cells.

Conclusion

IL-6 and STAT-3 are present in the invasion process of the normal placental development and they are maintained during the malignant transformation to choriocarcinoma. The intense telomerase expression observed in BeWo cells was strongly associated with the malignant phenotype, confirming it as a good marker for cell transformation and tumor progression.

Single-Cell RNA-seq Identifies Cell Subsets in Human Placenta That Highly Expresses Factors Driving Pathogenesis of SARS-CoV-2

Infection by the Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) results in the novel coronavirus disease COVID-19, which has posed a serious threat globally. Infection of SARS-CoV-2 during pregnancy is associated with complications such as preterm labor and premature rupture of membranes, and a proportion of neonates born to infected mothers are also positive for the virus. During pregnancy, the placental barrier protects the fetus from pathogens and ensures healthy development. To predict if the placenta is permissive to SARS-CoV-2, we utilized publicly available single-cell RNA-seq data to identify if the placental cells express the necessary factors required for infection. SARS-CoV-2 binding receptor ACE2 and the S protein priming protease TMPRSS2 are co-expressed by a subset of syncytiotrophoblasts (STB) in the first trimester and extravillous trophoblasts (EVT) in the second trimester human placenta. In addition, the non-canonical receptor BSG/CD147 and other proteases (CTSL, CTSB, and FURIN) are detected in most of the placental cells. Other coronavirus family receptors (ANPEP and DPP4) were also expressed in the first and second trimester placental cells. Additionally, the term placenta of multiple species including humans expressed ACE2, DPP4, and ANPEP along with the viral S protein proteases. The ACE2- and TMPRSS2-positive (ACE2 + TMPRSS2 +) placental subsets expressed mRNA for proteins involved in viral budding and replication. These cells also had the mRNA for proteins that physically interact with SARS-CoV-2 in host cells. Further, we discovered unique signatures of genes in ACE2 + TMPRSS2 + STBs and EVTs. The ACE2 + TMPRSS2 + STBs are highly differentiated cells and express genes involving mitochondrial metabolism and glucose transport. The second trimester ACE2 + TMPRSS2 + EVTs are enriched for markers of endovascular trophoblasts. Both these subtypes abundantly expressed genes in the Toll-like receptor pathway. The second trimester EVTs are also enriched for components of the JAK-STAT pathway that drives inflammation. We carried out a systematic review and identified that in 12% of pregnant women with COVID-19, the placenta was infected with SARS-CoV-2, and the virus was detected in STBs. To conclude, herein we have uncovered the cellular targets for SARS-CoV-2 entry and have shown that these cells can potentially drive viremia in the developing human placenta. Our results provide a basic framework toward understanding the paraphernalia involved in SARS-CoV-2 infections in pregnancy.

Trophoblast-derived IL-6 serves as an important factor for normal pregnancy by activating Stat3-mediated M2 macrophages polarization

Macrophages are major components of decidual microenvironment that play an important role in human implantation and placentation. Trophoblasts which migrate into the endometrium and interplay with decidual cells, have been reported to participate in the polarization of macrophages. However, the potential mechanisms of trophoblasts modulating M2 macrophages polarization still need further exploration. Herein, we used the co-cultured model to investigate the interaction between macrophages and trophoblasts. Our results illustrated that when co-cultured with trophoblasts, macrophages tended to polarize to M2-subtype, accompanied by increased expression of multiple M2 markers including CD206 and CCL18 mRNA expression and IL-10 and TGF-β protein level. Further experiments identified that trophoblast-derived IL-6, as the major contributor, promoted M2 macrophages polarization by activating Stat3 pathway. Moreover, activated M2 macrophages exerted a promoting role in the invasion and migration of trophoblasts in a feedback manner. Clinically, results from histology demonstrated that IL-6 expression in placental villous tissues was positive correlated with CD206-positive macrophage infiltration in decidua in normal pregnancy patients. Altogether, our findings indicate that trophoblasts induce M2 macrophages polarization via IL-6/Stat3 signal pathway, which in turn promote the invasion and migration of trophoblasts. These results provide insights into the crosstalk between macrophages and trophoblasts at maternal-fetal microenvironment in normal pregnancy.

MicroRNA-184 promotes apoptosis of trophoblast cells via targeting WIG1 and induces early spontaneous abortion

Recurrent spontaneous abortion (RSA) refers to the unintentional termination of two or more consecutive pregnancies that severely threatens human reproductive health. Our previous study has shown that miR-184 is expressed more highly in RSA than in normal pregnancy, whether in the villus or decidua. In this study, compared with normal pregnant women, the expression of miR-184 in decidual stromal cells (DSCs) and decidual immune cells (DICs), as well as in peripheral blood, from RSA patients was enhanced similarly. Moreover, we found miR-184 could promote the apoptosis and repress the proliferation of trophoblast cells. Further exploration indicated that miR-184 upregulated the expression of Fas by targeting WIG1 thus inducing cell apoptosis. Finally, after miR-184 overexpression in vivo, the embryo resorption rate in pregnant mice was increased significantly. Therefore, our study outlines the pivotal role of miR-184 in maintaining successful pregnancy, providing a new diagnostic and therapeutic target for RSA.

MicroRNA‑142‑3p inhibits trophoblast cell migration and invasion by disrupting the TGF‑β1/Smad3 signaling pathway

Insufficient invasion of trophoblasts is known to be associated with preeclampsia (PE) development. Recently, microRNAs (miRNAs) have been reported to serve important roles in the pathogenesis of PE. However, little is known regarding the regulation of trophoblastic invasion by miRNAs. The aim of the present study was to explore the role of miRNAs in trophoblastic invasion and the underlying molecular mechanism. Using a miRNA microarray, miRNAs putatively involved in the pathophysiology of PE were examined between normal and preeclamptic placentas. Validation analysis of miR‑142‑3p level in placenta specimens was performed using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). Then, the regulation of miR‑142‑3p on trophoblast cells migration and invasion was evaluated using wound healing and transwell migration assays. Furthermore, the target gene of miR‑142‑3p and the downstream signaling pathway were also investigated. Microarray analysis and RT‑qPCR revealed that miR‑142‑3p was significantly upregulated in placenta specimens from patients with PE. Its overexpression inhibited trophoblast cell invasion and migration, whereas its knockdown enhanced trophoblast cell invasion and migration. In addition, overexpression of miR‑142‑3p inhibited the mRNA expression and the activities of matrix metalloproteinase‑2 (MMP2) and MMP9, which are closely associated with cell invasion and migration, while inhibition of miR‑142‑3p had the opposite result. Subsequent analyses demonstrated that transforming growth factor‑β1 (TGF‑β1) was a direct and functional target of miR‑142‑3p. Notably, the knockdown of TGF‑β1 effectively reversed the enhancement of miR‑142‑3p inhibitor on trophoblast cell invasion and migration. Finally, the present study confirmed that miR‑142‑3p inhibitor enhanced cell invasion and migration by reactivating the TGF‑β1/Smad3 signaling pathway. Taken together, the results of the present study suggest that miR‑142‑3p may serve an important role in human placental development by suppressing trophoblast cell invasion and migration through disruption of the TGF‑β1/smad3 signaling pathway, suggesting that knockdown of miR‑142‑3p may provide a novel therapy for PE.

Trophoblast VIP deficiency entails immune homeostasis loss and adverse pregnancy outcome in mice

Immune homeostasis maintenance throughout pregnancy is critical for normal fetal development. Trophoblast cells differentiate into an invasive phenotype and contribute to the transformation of maternal arteries and the functional shaping of decidual leukocyte populations. Insufficient trophoblast invasion, inadequate vascular remodeling, and a loss of immunologic homeostasis are associated with pregnancy complications, such as preeclampsia and intrauterine growth restriction. Vasoactive intestinal peptide (VIP) is a pleiotropic neuropeptide synthetized in trophoblasts at the maternal-placental interface. It regulates the function of trophoblast cells and their interaction with decidual leukocytes. By means of a murine model of pregnancy in normal maternal background with VIP-deficient trophoblast cells, here we demonstrate that trophoblast VIP is critical for trophoblast function: VIP gene haploinsufficiency results in lower matrix metalloproteinase 9 expression, and reduced migration and invasion capacities. A reduced number of regulatory T cells at the implantation sites along with a lower expression of proangiogenic and antiinflammatory markers were also observed. Findings detected in the implantation sites at early stages were followed by an abnormal placental structure and lower fetal weight. This effect was overcome by VIP treatment of the early pregnant mice. Our results support the relevance of trophoblast-synthesized VIP as a critical factor in vivo for trophoblast-cell function and immune homeostasis maintenance in mouse pregnancy.-Hauk, V., Vota, D., Gallino, L., Calo, G., Paparini, D., Merech, F., Ochoa, F., Zotta, E., Ramhorst, R., Waschek, J., Leirós, C. P. Trophoblast VIP deficiency entails immune homeostasis loss and adverse pregnancy outcome in mice.

Elevated Tristetraprolin Impairs Trophoblast Invasion in Women with Recurrent Miscarriage by Destabilization of HOTAIR

Tristetraprolin (TTP) regulates the stability of multiple targets that have important biological roles. However, the role of TTP in trophoblasts at the maternal-fetal interface remains poorly understood. We demonstrated that TTP was upregulated in placental trophoblasts from patients with recurrent miscarriages (RMs). Immunofluorescence and immunoblotting analyses indicated that TTP was redistributed from the nucleus to the cytoplasm in trophoblasts from patients with RMs. Trophoblast invasion and proliferation was repressed by TTP overexpression and was enhanced by TTP knockdown. Interestingly, TTP knockdown promoted trophoblast invasion in an ex vivo explant culture model. Furthermore, TTP overexpression in trophoblasts significantly inhibited the expression of the long non-coding RNA (lncRNA) HOTAIR. TTP was found to regulate HOTAIR expression by a posttranscriptional mechanism. To RNA immunoprecipitation (RIP) and RNA-protein, pull-down identified TTP as a specific binding partner that decreased the half-life of HOTAIR and lowered steady-state HOTAIR expression levels, indicating a novel posttranscriptional regulatory mechanism. Our findings identify a novel function for TTP in lncRNA regulation and provide important insights into the regulation of lncRNA expression. This study reveals a new pathway governing the regulation of TTP/HOTAIR in trophoblast cell invasion during early pregnancy.

Cancer cell transmission via the placenta

Cancer cells have a parasitic propensity in the primary host but their capacity to transit between individuals is severely restrained by two factors: a lack of a route for viable cell transfer and immune recognition in allogeneic, secondary recipients. Several examples of transmissible animal cancers are now recognised. In humans, the only natural route for transmission is via the haemochorial placenta which is permissive for cell traffic. There are three special examples of this occurring in utero: maternal to foetus, intraplacental twin to twin leukaemias and choriocarcinoma-extra-embryonic cells to mother. We discuss the rare circumstances under which such transmission occurs.

Transforming growth factor β1 promotes invasion of human JEG-3 trophoblast cells via TGF-β/Smad3 signaling pathway

Transforming growth factor (TGF)-β1 is involved invasion of human trophoblasts. However, the underlying mechanisms remain unclear. In this study, we performed Transwell assay and found that TGF-β1 promoted the invasion of trophoblast cell line JEG-3. Treatment with TGF-β1 up-regulated the expression of receptor-regulated Smad transcription factors Smad2 and Smad3, and two invasive-associated genes, namely, matrix metallopeptidase (MMP)-9 and MMP-2, in JEG-3 cells. Over-expressing activin receptor-like kinase (ALK) 5, the TGF-β type I receptor (TβRI) enhanced the up-regulation of Smad2, Smad3, MMP-9, and MMP-2 induced by TGF-β1, whereas application of TβRI inhibitor SB431542 diminished the stimulatory effects of TGF-β1 on these genes. Furthermore, transfection of Smad3 and ALK-5 seperately or in combination into JEG-3 cells before TGF-β1 treatment significantly increased the expression of MMP-9 and MMP-2. By contrast, silencing Smad3 and Smad2 by siRNAs significantly decreased the expression of MMP-9 and MMP-2, with Smad3 silence having a more potent inhibitory effect. Inhibiting TβRI with SB431542 or knockdown of Smad3, but not Smad2, abolished the stimulatory effect of TGF-β1 on the invasion of JEG-3 cells. Taken together, the results indicate that TGF-β1 activates the Smads signaling pathway in JEG-3 trophoblast cells and Smad3 play a key role in TGF-β1-induced invasion of JEG-3 and up-regulation of MMP-9 and MMP-2 expression.

MXRA5 is decreased in preeclampsia and affects trophoblast cell invasion through the MAPK pathway

Preeclampsia causes gestational failure in a significant number of women annually. Insufficient trophoblast cell invasion plays an essential role in preeclampsia pathogenesis. Matrix-remodeling associated 5 (MXRA5) is a proteoglycan involved in adhesion and matrix remodeling. This study sought to explore the role of MXRA5 in trophoblast cell invasion. Preeclamptic villi were obtained for the delineation of MXRA5 expression. Specific MXRA5 siRNA and pcDNA3.1/MXRA5 were used to manipulate MXRA5 expression in HTR-8/SVneo. Cell viability was determined by MTT and apoptosis by flow cytometry. Cell invasion was evaluated using Matrigel invasion assay. MXRA5 expression was lower in preeclamptic villi and cytotrophoblasts. Silencing MXRA5 expression in HTR-8/SVneo decreased cell viability and invasion, which were augmented by MXRA5 overexpression. Furthermore, MXRA5 modulated N-cadherin, E-cadherin, MMP-2, and MMP-9 expression through p38 MAPK and ERK1/2 signaling transduction. In addition, the expression of MXRA5 was influenced by exogenous TNF-α but not by IFN-γ. Overexpression of MXRA5 attenuated HTR-8/SVneo apoptosis induced by TNF-α. MXRA5 is downregulated in preeclamptic cytotrophoblasts and can regulate trophoblast cell invasion via the MAPK pathway.

Embryo Implantation: War in Times of Love

Contrary to widespread belief, the implantation of an embryo for the initiation of pregnancy is like a battle, in that the embryo uses a variety of coercive tactics to force its acceptance by the endometrium. We propose that embryo implantation involves a three-step process: (1) identification of a receptive endometrium; (2) superimposition of a blastocyst-derived signature onto the receptive endometrium before implantation; and finally (3) breaching by the embryo and trophoblast invasion, culminating in decidualization and placentation. We review here the story that is beginning to emerge, focusing primarily on the cells that are in "combat" during this process.

Promoter Methylation Status of WNT2 in Placenta from Patients with Preeclampsia

Background

Preeclampsia is a serious multisystem disorder of human gestation, affecting up to 10% of pregnant women worldwide, and results in maternal morbidity and mortality. The aim of this study was to determine the gene expression pattern and methylation status of the promoter of the WNT2 gene in placentas from patients with preeclampsia and to evaluate the potential role of the WNT2 pathway in the pathogenesis of preeclampsia.

Material/Methods

Real-time quantitative polymerase chain reaction (PT-PCR) was used to determine the WNT2 gene expression level. Western blot analysis was used to identify alterations in wnt2 protein expression.

Results

The mRNA and protein expression levels of the WNT2 gene were reduced in placentas from patients with preeclampsia when compared with placentas from healthy women. The average methylation level of the promoter of the WNT2 gene was elevated in the placentas from patients with preeclampsia compared with the controls placentas from healthy women.

Conclusions

The findings of this study have shown that molecular mechanisms, including aberrant activation of the WNT2 gene signaling pathway, may be involved in the pathogenesis of preeclampsia. Promoter hypermethylation and reduced expression of the WNT2 gene requires further study to determine a potential role in the diagnosis and treatment of preeclampsia.

Interdependence of JAK-STAT and MAPK signaling pathways during EGF-mediated HTR-8/SVneo cell invasion

Invasion of trophoblast cells is spatio-temporally regulated by various cytokines and growth factors. In pregnancy, complications like preeclampsia, shallow invasion of trophoblast cells and low amounts of epidermal growth factor (EGF) have been reported. In the present study, regulatory mechanisms associated with EGF-mediated invasion in HTR-8/SVneo trophoblastic cells have been delineated. Treatment of HTR-8/SVneo cells with EGF (10 ng/ml) led to eight fold increase (p < 0.05) in invasion. Increased invasion of HTR-8/SVneo cells by EGF was associated with an increase in phosphorylation of ERK½. In addition, significant phosphorylation of STAT1 (ser 727) and STAT3 (both tyr 705 and ser 727 residues) was also observed, accompanied by a decrease in total STAT1. Inhibition of ERK½ phosphorylation by U0126 (10 μM) led to a significant decrease in EGF-mediated invasion with simultaneous decrease in the phosphorylated forms of STAT3 and STAT1. Decrease in total STAT1 was also reversed on inhibition of ERK½. Interestingly, inhibition of STAT3 by siRNA led to a significant decrease in EGF-mediated invasion of HTR-8/SVneo cells and phosphorylation of STAT1, but it did not have any effect on the activation of ERK½. On the other hand, inhibition of STAT1 by siRNA, also led to a significant decrease in the EGF-mediated invasion of HTR-8/SVneo cells, showed concomitant decrease in ERK½ phosphorylation and STAT3 phosphorylation at ser 727 residue. These results suggest cross-communication between ERK½ and JAK-STAT pathways during EGF-mediated increase in invasion of trophoblast cells; phosphorylation at ser 727 residue of both STAT3 and STAT1 appears to be critical.

Role of Wnt signalling in early pregnancy

The integration of a complex network of signalling molecules promotes implantation of the blastocyst and development of the placenta. These processes are crucial for a successful pregnancy and fetal growth and development. The signalling network involves both cell-cell and cell-extracellular matrix communication. The family of secreted glycoprotein ligands, the Wnts, plays a major role in regulating a wide range of biological processes, including embryonic development, cell fate, proliferation, migration, stem cell maintenance, tumour suppression, oncogenesis and tissue homeostasis. Recent studies have provided evidence that Wnt signalling pathways play an important role in reproductive tissues and in early pregnancy events. The focus of this review is to summarise our present knowledge of expression, regulation and function of the Wnt signalling pathways in early pregnancy events of human and other model systems, and its association with pathological conditions. Despite our recent progress, much remains to be learned about Wnt signalling in human reproduction. The advancement of knowledge in this area has applications in the reduction of infertility and the incidence and morbidity of gestational diseases.

Forkhead box a2 (FOXA2) is essential for uterine function and fertility

Establishment of pregnancy is a critical event, and failure of embryo implantation and stromal decidualization in the uterus contribute to significant numbers of pregnancy losses in women. Glands of the uterus are essential for establishment of pregnancy in mice and likely in humans. Forkhead box a2 (FOXA2) is a transcription factor expressed specifically in the glands of the uterus and is a critical regulator of postnatal uterine gland differentiation in mice. In this study, we conditionally deleted FOXA2 in the adult mouse uterus using the lactotransferrin Cre (Ltf-Cre) model and in the neonatal mouse uterus using the progesterone receptor Cre (Pgr-Cre) model. The uteri of adult FOXA2-deleted mice were morphologically normal and contained glands, whereas the uteri of neonatal FOXA2-deleted mice were completely aglandular. Notably, adult FOXA2-deleted mice are completely infertile because of defects in blastocyst implantation and stromal cell decidualization. Leukemia inhibitory factor (LIF), a critical implantation factor of uterine gland origin, was not expressed during early pregnancy in adult FOXA2-deleted mice. Intriguingly, i.p. injections of LIF initiated blastocyst implantation in the uteri of both gland-containing and glandless adult FOXA2-deleted mice. Although pregnancy was rescued by LIF and was maintained to term in uterine gland-containing adult FOXA2-deleted mice, pregnancy failed by day 10 in neonatal FOXA2-deleted mice lacking uterine glands. These studies reveal a previously unrecognized role for FOXA2 in regulation of adult uterine function and fertility and provide original evidence that uterine glands and, by inference, their secretions play important roles in blastocyst implantation and stromal cell decidualization.

Acute alcohol exposure during mouse gastrulation alters lipid metabolism in placental and heart development: Folate prevention

Background

Embryonic acute exposure to ethanol (EtOH), lithium, and homocysteine (HCy) induces cardiac defects at the time of exposure; folic acid (FA) supplementation protects normal cardiogenesis (Han et al., 2009, 2012; Serrano et al., 2010). Our hypothesis is that EtOH exposure and FA protection relate to lipid and FA metabolism during mouse cardiogenesis and placentation.

Methods

On the morning of conception, pregnant C57BL/6J mice were placed on either of two FA‐containing diets: a 3.3 mg health maintenance diet or a high FA diet of 10.5 mg/kg. Mice were injected a binge level of EtOH, HCy, or saline on embryonic day (E) 6.75, targeting gastrulation. On E15.5, cardiac and umbilical blood flow were examined by ultrasound. Embryonic cardiac tissues were processed for gene expression of lipid and FA metabolism; the placenta and heart tissues for neutral lipid droplets, or for medium chain acyl‐dehydrogenase (MCAD) protein.

Results

EtOH exposure altered lipid‐related gene expression on E7.5 in comparison to control or FA‐supplemented groups and remained altered on E15.5 similarly to changes with HCy, signifying FA deficiency. In comparison to control tissues, the lipid‐related acyl CoA dehydrogenase medium length chain gene and its protein MCAD were altered with EtOH exposure, as were neutral lipid droplet localization in the heart and placenta.

Conclusion

EtOH altered gene expression associated with lipid and folate metabolism, as well as neutral lipids, in the E15.5 abnormally functioning heart and placenta. In comparison to controls, the high FA diet protected the embryo and placenta from these effects allowing normal development. Birth Defects Research (Part A) 106:749–760, 2016. © 2016 The Authors Birth Defects Research Part A: Clinical and Molecular Teratology Published by Wiley Periodicals, Inc.

Association of aberrant methylation at promoter regions of tumor suppressor genes with placental pathologies

Aim: The resemblance between invasive behavior of cancer cells and placental trophoblasts and the role of aberrant epigenetic regulation in cancer development is well known. Methods: We analyzed the role of promoter region CpG-methylation and H3K9/27me3 of tumor suppressor genes in normal and pathological pregnancies and utilized their CpG-methylation data to search for fetal DNA epigenetic marker in maternal blood. Results: CpG and H3K9/27-methylation associated decreased expression of RASSF1A and APC and increased expression of P16, RB1 and PRKCDBP was observed with advancing normal gestation. Gestational trophoblastic diseases and preeclampsia revealed gene-specific epigenetic deregulation of candidate tumor suppressor genes. Furthermore, APC and PRKCDBP showed the potential to act as fetal DNA epigenetic markers, similar to RASSF1A. Conclusion: Deregulation of methylation of tumor suppressor genes contributes to the development of preeclampsia and gestational trophoblastic diseases. APC and PRKCDBP may act as fetal DNA epigenetic markers for prenatal diagnosis.

Evidence from the very beginning: endoglandular trophoblasts penetrate and replace uterine glands in situ and in vitro

STUDY QUESTION

How is histiotrophic nutrition of the embryo secured during the first trimester of pregnancy?

SUMMARY ANSWER

Rather than specifically focusing on invasion into spiral arteries, extravillous trophoblasts also invade into uterine glands (endoglandular trophoblast) from the very beginning and open them toward the intervillous space.

WHAT IS KNOWN ALREADY

Extravillous trophoblasts can be found in close contact and within the lumen of uterine glands, sometimes replacing glandular epithelial cells.

STUDY DESIGN, SIZE, DURATION

As well as extensive screening of specimens from first trimester placentation sites in situ we used a previously established three-dimensional co-culture in vitro model system of first trimester villous explants with non-invaded decidua parietalis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

First trimester placentas were obtained from elective terminations of pregnancies (n = 48) at 5-11 weeks of gestational age. A subset was processed for confrontation co-culture (n = 31). Invaded decidua basalis was obtained from 20 placentas. All tissues were sectioned, subsequently immunostained and immunodoublestained with antibodies against keratin 7 (KRT7), major histocompatibility complex, class I, G (HLA-G), matrix metallopeptidase 9 (MMP9), von Willebrand factor (VWF) and the appropriate Immunoglobulin G (IgG) negative controls. Replacement of endothelial/epithelial cells by extravillous trophoblasts was quantified semi-quantitatively. Additionally, hematoxylin and eosin-stained archival specimens from early implantation sites were assessed.

MAIN RESULTS AND THE ROLE OF CHANCE

The earliest available specimen was from around Day 10 after conception; already at this stage trophoblasts had penetrated into uterine glands and had started to replace the epithelium of the glands. Endoglandular trophoblasts replaced uterine glands in vitro and in situ and could be found in the lumen of invaded glands. Quantitative analysis revealed significantly more replacement of epithelial cells in glands (63.8 ± 22.1%) compared with endothelial cells in vessels (26.4 ± 8.8%). Accumulated detached glandular epithelial cells could be repeatedly observed in the lumen of invaded glands. Additionally, in areas of trophoblast invasion the glandular epithelium seemed to be completely disintegrated compared with glandular epithelium in the non-invaded parts of the decidua. Whole tissue specimens were used in vitro and in situ instead of cell lines; these systems mostly maintain the context of the in vivo situation.

LIMITATIONS, REASONS FOR CAUTION

This is a descriptive study supported by in vitro experiments. However, a histological section will always only be a snapshot and quantification from histological sections has its limitations.

WIDER IMPLICATIONS OF THE FINDINGS

This study further strengthens the hypothesis of histiotrophic nutrition of the embryo prior to the establishment of the maternal blood flow toward the placenta. Invasion of uterine glands by endoglandular trophoblasts may have more impact on the outcome of early pregnancy than assumed up to now.

Gal-1 silenced trophoblast tumor cells (BeWo) show decreased syncytium formation and different miRNA production compared to non-target silenced BeWo cells

Galectin-1 (gal-1), a member of the mammalian β-galactoside-binding proteins, exerts biological effects by recognition of glycan ligands, including those involved in cell adhesion and growth regulation. In previous studies, we demonstrated that gal-1 induces cell differentiation processes on the membrane of choriocarcinoma cells BeWo, including the receptor tyrosine kinases (RTKs) REarranged during Transfection (RET), Janus Kinase 2 (JAK2) and Vascular endothelial growth factor receptor 3 (VEGFR3). Furthermore, Mitogen-Activated Protein Kinases (MAPK) and serine/threonine kinases were phosphorylated by gal-1. In addition, gal-1 in trophoblast cells in vitro induced syncytium formation especially after concentration dependent stimulation of the cells with this galectin. This is in contrast to MAPK-inhibitor U0126 that reduced syncytium formation of BeWo cells. The aim of this study was to analyze the syncytium formation abilities of BeWo cells that were gal-1 silenced. We found a significantly reduced syncytium formation rate in gal-1 silenced BeWo cells. In addition, these cells show a different miRNA expression profile. In summary, we found that gal-1 is a major trigger for fusion processes in BeWo cells. This function is accompanied by different regulation of miRNA synthesis in the BeWo cell culture model.

Molecular Cross-Talk at the Feto-Maternal Interface

Molecular cross-talk at the feto-maternal interface occurs between many different cell types, including uterine leukocytes, extravillous trophoblast cells, and uterine spiral arteries, is essential for the establishment and maintenance of pregnancy. This review concentrates on human pregnancy and examines three main areas in which cross-talk occurs; immune tolerance, regulation of extravillous trophoblast invasion, and remodeling of the uterine spiral arteries.

An EG-VEGF-Dependent Decrease in Homeobox Gene NKX3.1 Contributes to Cytotrophoblast Dysfunction: A Possible Mechanism in Human Fetal Growth Restriction

Idiopathic fetal growth restriction (FGR) is frequently associated with placental insufficiency. Previous reports have provided evidence that endocrine gland-derived vascular endothelial growth factor (EG-VEGF), a placental secreted protein, is expressed during the first trimester of pregnancy, controls both trophoblast proliferation and invasion, and its increased expression is associated with human FGR. In this study, we hypothesize that EG-VEGF-dependent changes in placental homeobox gene expressions contribute to trophoblast dysfunction in idiopathic FGR. The changes in EG-VEGF-dependent homeobox gene expressions were determined using a homeobox gene cDNA array on placental explants of 8-12 wks gestation after stimulation with EG-VEGF in vitro for 24 h. The homeobox gene array identified a greater-than-five-fold increase in HOXA9, HOXC8, HOXC10, HOXD1, HOXD8, HOXD9 and HOXD11, while NKX 3.1 showed a greater-than-two-fold decrease in mRNA expression compared with untreated controls. Homeobox gene NKX3.1 was selected as a candidate because it is a downstream target of EG-VEGF and its expression and functional roles are largely unknown in control and idiopathic FGR-affected placentae. Real-time PCR and immunoblotting showed a significant decrease in NKX3.1 mRNA and protein levels, respectively, in placentae from FGR compared with control pregnancies. Gene inactivation in vitro using short-interference RNA specific for NKX3.1 demonstrated an increase in BeWo cell differentiation and a decrease in HTR-8/SVneo proliferation. We conclude that the decreased expression of homeobox gene NKX3.1 downstream of EG-VEGF may contribute to the trophoblast dysfunction associated with idiopathic FGR pregnancies.

Decreased STAT3 in human idiopathic fetal growth restriction contributes to trophoblast dysfunction

Abnormal trophoblast function is associated with fetal growth restriction (FGR). The JAK-STAT pathway is one of the principal signalling mechanisms by which cytokines and growth factors modulate cell proliferation, differentiation, cell migration and apoptosis. The expression of placental JAK-STAT genes in human idiopathic FGR is unknown. In this study, we propose the hypothesis that JAK-STAT pathway genes are differentially expressed in idiopathic FGR-affected pregnancies and contribute to abnormal feto-placental growth by modulating the expression of the amino acid transporter SNAT2, differentiation marker CGB/human chorionic gonadotrophin beta-subunit (β-hCG) and apoptosis markers caspases 3 and 8, and TP53. Expression profiling of FGR-affected placentae revealed that mRNA levels of STAT3, STAT2 and STAT5B decreased by 69, 52 and 50%, respectively, compared with gestational-age-matched controls. Further validation by real-time PCR and immunoblotting confirmed significantly lower STAT3 mRNA and STAT3 protein (total and phosphorylated) levels in FGR placentae. STAT3 protein was localised to the syncytiotrophoblast (ST) in both FGR and control placentae. ST differentiation was modelled by in vitro differentiation of primary villous trophoblast cells from first-trimester and term placentae, and by treating choriocarcinoma-derived BeWo cells with forskolin in cell culture. Differentiation in these models was associated with increased STAT3 mRNA and protein levels. In BeWo cells treated with siRNA targeting STAT3, the mRNA and protein levels of CGB/β-hCG, caspases 3 and 8, and TP53 were significantly increased, while that of SNAT2 was significantly decreased compared with the negative control siRNA. In conclusion, we report that decreased STAT3 expression in placentae may contribute to abnormal trophoblast function in idiopathic FGR-affected pregnancies.

LIMK1 regulates human trophoblast invasion/differentiation and is down-regulated in preeclampsia

Successful human pregnancy requires extensive invasion of maternal uterine tissues by the placenta. Invasive extravillous trophoblasts derived from cytotrophoblast progenitors remodel maternal arterioles to promote blood flow to the placenta. In the pregnancy complication preeclampsia, extravillous trophoblasts invasion and vessel remodeling are frequently impaired, likely contributing to fetal underperfusion and maternal hypertension. We recently demonstrated in mouse trophoblast stem cells that hypoxia-inducible factor-2 (HIF-2)-dependent Lim domain kinase 1 (LIMK1) expression regulates invasive trophoblast differentiation by modulating the trophoblast cytoskeleton. Interestingly, in humans, LIMK1 activity promotes tumor cell invasion by modulating actin and microtubule integrity, as well as by modulating matrix metalloprotease processing. Here, we tested whether HIF-2α and LIMK1 expression patterns suggested similar roles in the human placenta. We found that LIMK1 immunoreactivity mirrored HIF-2α in the human placenta in utero and that LIMK1 activity regulated human cytotrophoblast cytoskeletal integrity, matrix metallopeptidase-9 secretion, invasion, and differentiation in vitro. Importantly, we also found that LIMK1 levels are frequently diminished in the preeclampsia setting in vivo. Our results therefore validate the use of mouse trophoblast stem cells as a discovery platform for human placentation disorders and suggest that LIMK1 activity helps promote human placental development in utero.

Association of tissue inhibitor of metalloproteinase gene polymorphisms and unexplained recurrent spontaneous abortions in Han Chinese couples

OBJECTIVE

To investigate the association of tissue inhibitor of metalloproteinase (TIMP) gene polymorphisms with unexplained recurrent spontaneous abortions (URSA) in a well-defined group of Han Chinese couples.

STUDY DESIGN

This is a case-control association study. Genomic DNA was extracted from peripheral blood samples from 84 couples with histories of three or more pregnancy losses and 69 age-matched healthy couples with at least one live birth and no histories of pregnancy loss. Polymerase chain reactions (PCRs) and sequencing with the fluorescent dye dideoxy-termination method were used to detect the rs4898 in TIMP-1, rs2277698 in TIMP-2, rs2234921 and rs5749511 in TIMP-3 and rs17035945 in TIMP-4 genotypes and allele frequencies.

RESULTS

Neither the allele frequencies nor any of the genetic model of the five TIMP gene SNPs (i.e., TIMP-1-rs4898, TIMP-2-rs2277698, TIMP-3-rs5749511 and rs2234921, and TIMP-4-rs7035945) were significantly differences between the URSA couples and the control group.

CONCLUSIONS

No evidence was found for any associations between the TIMP-1,-2,-3, or -4 genes SNPs with URSA in this Han Chinese Han.

Galectin-7 is important for normal uterine repair following menstruation

Menstruation involves the shedding of the functional layer of the endometrium in the absence of pregnancy. At sites where tissue shedding is complete, re-epithelialization of the tissue is essential for repair and termination of bleeding. The complement of growth factors that mediate post-menstrual endometrial repair are yet to be completely elucidated. Galectins regulate many cell functions important for post-menstrual repair, such as cell adhesion and migration. Galectin-7 has a well characterized role in re-epithelialization and wound healing. We hypothesized that galectin-7 would be important in re-epithelialization during post-menstrual repair. We aimed to identify endometrial expression of galectin-7 in women undergoing normal endometrial repair and in women with amenorrhoea who do not experience endometrial breakdown and repair, and to determine whether galectin-7 enhances endometrial re-epithelialization in vitro. Galectin-7 immunolocalized to the endometrial luminal and glandular epithelium during the late secretory and menstrual phases, and to decidualized stroma in regions exhibiting tissue breakdown. Immunostaining intensity was significantly reduced in the endometrium of women with amenorrhoea compared with normally cycling woman. ELISA identified galectin-7 in menstrual fluid at significantly elevated levels compared with matched peripheral plasma. Exogenous galectin-7 (2.5 µg/ml) significantly enhanced endometrial epithelial wound repair in vitro; this was abrogated by inhibition of integrin binding. Galectin-7 elevated epithelial expression of extracellular matrix-related molecules likely involved in repair including β-catenin, contactin and TGF-β1. In conclusion, galectin-7 is produced by the premenstrual and menstrual endometrium, where it accumulates in menstrual fluid and likely acts as a paracrine factor to facilitate post-menstrual endometrial re-epithelialization.

DNA methyltransferases and TETs in the regulation of differentiation and invasiveness of extra-villous trophoblasts

Specialized cell types of trophoblast cells form the placenta in which each cell type has particular properties of proliferation and invasion. The placenta sustains the growth of the fetus throughout pregnancy and any aberrant trophoblast differentiation or invasion potentially affects the future health of the child and adult. Recently, the field of epigenetics has been applied to understand differentiation of trophoblast lineages and embryonic stem cells (ESC), from fertilization of the oocyte onward. Each trophoblast cell-type has a distinctive epigenetic profile and we will concentrate on the epigenetic mechanism of DNA methyltransferases and TETs that regulate DNA methylation. Environmental factors affecting the mother potentially regulate the DNA methyltransferases in trophoblasts, and so do steroid hormones, cell cycle regulators, such as p53, and cytokines, especially interlukin-1β. There are interesting questions of why trophoblast genomes are globally hypomethylated yet specific genes can be suppressed by hypermethylation (in general, tumor suppressor genes, such as E-cadherin) and how invasive cell-types are liable to have condensed chromatin, as in metastatic cancer cells. Future work will attempt to understand the interactive nature of all epigenetic mechanisms together and their effect on the complex biological system of trophoblast differentiation and invasion in normal as well as pathological conditions.

Decidual angiogenesis and placental orientation are altered in mice heterozygous for a dominant loss-of-function Gja1 (connexin43) mutation

Connexin43 (CX43), encoded by Gja1 in the mouse, is highly expressed in decidual cells and is known to be important for the transformation of stromal cells into the compact decidua and for neoangiogenesis. Here we investigated if the dominant Gja1(Jrt) mutation encoding CX43(G60S) in mice, which results in a phenotype resembling oculodentodigital dysplasia in humans, has an impact on decidualization, angiogenesis, and implantation. We found a reduced mean weight of fetuses at Gestational Day 17.5 in dams carrying this mutation, with the growth deficiency being independent of fetal genotype. Although the mutant implantation sites exhibited a reduction in CX43 protein, with most immunoreactivity being cytoplasmic, the decidua was morphologically intact at Embryonic Days 5.5 to 7.5. However, the mutation resulted in enhanced and irregular angiogenesis and an increased level of expression of the angiogenic factor-encoding genes Vegfa, Flt1, Kdr, and Fgf2 as well as the prolactin-related gene Prl6a. Moreover, immunolocalization of VEGFA, FLT1, and KDR revealed a homogeneous distribution pattern in the mesometrial as well as antimesometrial decidua of the mutants. Most obviously, uterine NK cells are drastically diminished in the mesometrial decidua of the mutant mice. Invasion of ectoplacental cone cells was disoriented, and placentation was established more laterally in the implantation chambers. It was concluded that the CX43(G60S) mutant impairs control of decidual angiogenesis, leading to dysmorphic placentation and fetal growth restriction. This phenomenon could contribute to the reduced fetal weights and viability of pups born of Gja1(Jrt)/+ dams.

Intranuclear crosstalk between extracellular regulated kinase1/2 and signal transducer and activator of transcription 3 regulates JEG-3 choriocarcinoma cell invasion and proliferation

Invasiveness of trophoblast and choriocarcinoma cells is in part mediated via leukemia inhibitory factor- (LIF-) induced activation of signal transducer and activator of transcription 3 (STAT3). The regulation of STAT3 phosphorylation at its ser727 binding site, possible crosstalk with intracellular MAPK signaling, and their functional implications are the object of the present investigation. JEG-3 choriocarcinoma cells were cultured in presence/absence of LIF and the specific ERK1/2 inhibitor (U0126). Phosphorylation of signaling molecules (p-STAT3 (ser727 and tyr705) and p-ERK1/2 (thr 202/tyr 204)) was assessed per Western blot. Immunocytochemistry confirmed results, but also pinpointed the location of phosphorylated signaling molecules. STAT3 DNA-binding capacity was studied with a colorimetric ELISA-based assay. Cell viability and invasion capability were assessed by MTS and Matrigel assays. Our results demonstrate that LIF-induced phosphorylation of STAT3 (tyr705 and ser727) is significantly increased after blocking ERK1/2. STAT3 DNA-binding capacity and cell invasiveness are enhanced after LIF stimulation and ERK1/2 blockage. In contrast, proliferation is enhanced by LIF but reduced after ERK1/2 inhibition. The findings herein show that blocking ERK1/2 increases LIF-induced STAT3 phosphorylation and STAT3 DNA-binding capacity by an intranuclear crosstalk, which leads to enhanced invasiveness and reduced proliferation.

Expression and function of galectins in the endometrium and at the human feto-maternal interface

Galectins are classified as lectins that share structural similarities and bind β-galactosides via a conserved carbohydrate recognition domain. So far 16 out of 19 identified galectins were shown to be present in humans and numerous studies revealed galectins as pivotal modulators of cell death, differentiation and growth. Galectins were highlighted to interact with both the adaptive and innate immune response. In the field of reproductive medicine and placenta research different roles for galectins have been proposed. Several galectins, being abundantly present at the human feto-maternal interphase and endometrium, were hypothesized to significantly contribute to endometrial receptivity and pregnancy physiology. Hence, this review outlines selected aspects of galectin action within endometrial function and at the feto-maternal interphase. Further current knowledge on galectins in reproductive and pregnancy disorders like endometriosis, abortion or preeclampsia is summarized.

The heart-placenta axis in the first month of pregnancy: induction and prevention of cardiovascular birth defects

Extrapolating from animal studies to human pregnancy, our studies showed that folate (FA) deficiency as well as one-time exposure to environmental factors in the first two to three weeks of human gestation can result in severe congenital heart defects (CHDs). Considering that approximately 49% of pregnancies are unplanned, this period of pregnancy can be considered high-risk for cardiac, as well as for neural, birth defects, as the woman usually is not aware of her pregnancy and may not yet be taking precautionary actions to protect the developing embryo. Using avian and mouse vertebrate models, we demonstrated that FA supplementation prevents CHD induced by alcohol, lithium, or elevation of the metabolite homocysteine, a marker for FA deficiency. All three factors affected the important Wnt signaling pathway by suppressing Wnt-mediated gene expression in the heart fields, resulting in a delay of cardiomyocyte migration, cardiomyogenesis, and CHD. Optimal protection of cardiogenesis was observed to occur with FA supplementation provided upon morning after conception and at higher doses than the presently available in prenatal vitamin supplementation. Our studies demonstrate pathways and cell processes that are involved with protection of one-carbon metabolism during heart development.