Complex expression pattern of Wnt ligands and frizzled receptors in human placenta and its trophoblast subtypes

Stem Cell Markers LGR5, LGR4 and Their Immediate Signalling Partners are Dysregulated in Preeclampsia

Leucine-rich repeat-containing G protein-coupled receptors 5/4 (LGR5/LGR4) are critical stem cell markers in epithelial tissues including intestine. They agonise wingless-related integration site (WNT) signalling. Until now, LGR5/LGR4 were uncharacterised in placenta, where analogous functions may exist. We characterised LGR5/LGR4, their ligands/targets in human placenta, with further assessments on dysregulation in preeclampsia/fetal growth restriction (FGR). LGR5 mRNA was unaltered in first trimester (n = 11), preterm (n = 9) and term (n = 11) placental lysate. LGR5 was enriched in human trophoblast stem cells (hTSCs) and downregulated with differentiation to extravillous trophoblasts (p < 0.0215) and syncytiotrophoblasts (p < 0.0350). In situ hybridisation localised LGR5 to unique, proliferative MKI67 + mononuclear trophoblasts underlying syncytium which concurred with proposed progenitor identities in single-cell transcriptomics. LGR5 expression was significantly reduced in placentas from early-onset preeclampsia (p < 0.0001, n = 81 versus n = 19 controls), late-onset preeclampsia (p = 0.0046, n = 20 versus n = 33 controls) and FGR (p = 0.0031, n = 34 versus n = 17 controls). LGR4 was elevated in first trimester versus preterm and term placentas (p = 0.0412), in placentas with early-onset preeclampsia (p = 0.0148) and in FGR (p = 0.0417). Transcriptomic analysis and in vitro hTSC differentiation to both trophoblast lineages suggested LGR4 increases with differentiation. Single-nucleus RNA sequencing of placental villous samples supported LGR5 and LGR4 localisation findings. Hypoxia/proinflammatory cytokine treatment modelling elements experienced by the placenta in placental insufficiency pathogenesis did not significantly alter LGR5/LGR4. Ligands R-spondins 1/3/4, and neutralising targets ring finger protein 43 (RNF43) and zinc and ring finger 3 (ZNRF3) were also reduced in placentas from preeclamptic pregnancies. This study is the first to describe LGR5/LGR4 and their signalling partner expression in human placenta. Their dysregulations in the preeclamptic placenta allude to disruptions to integral trophoblast stem cell function/differentiation that may occur during placental development related to WNT signalling.

Down-regulation of PCBP2 suppresses the invasion and migration of trophoblasts via the WNT5A/ROR2 pathway in preeclampsia†

Impaired extravillous trophoblast (EVT) invasion and resulted poor placentation play a vital role in the development of preeclampsia (PE). However, the underlying mechanisms of dysregulated EVTs remain unclear. This study aimed to explore the role of poly (C)-binding protein 2 (PCBP2), a multifunctional RNA-binding protein, in the pathogenesis of PE and to investigate the detailed signaling pathway. Using qRT-PCR, western blot, and immunohistochemistry, we confirmed that the expression of PCBP2 significantly decreased in placentas from 18 early-onset PE and 30 late-onset PE in comparison to those from 30 normotensive pregnancies. Besides, more significant suppression of PCBP2 was observed in the early-onset type. After transfection of HTR-8/SVneo with small-interfering RNA specific to PCBP2, the cellular biological behaviors including vitality, immigration, invasiveness, and apoptosis were evaluated by CCK-8 assay, wound-healing assay, transwell assay, and flow cytometry respectively. RNA-seq was applied to screen differentially expressed genes in HTR-8/SVneo upon PCBP2 silencing. GO and KEGG analysis indicated that WNT signaling pathway and the related processes such as extracellular matrix remodeling and cell adhesion were among the most enriched pathways or processes. Meanwhile, the alternative splicing of WNT5A regulated by PCBP2 was also identified by RIP-seq. Based on HTR-8/SVneo and villous explant, the regulatory roles of PCBP2 on trophoblast were confirmed to be mediated by WNT5A. Besides, it revealed that ROR2/JNK/MMP2/9 pathway was a vital pathway downstream WNT5A in trophoblast cells. In conclusion, this study suggests that down-regulated PCBP2 impaired the functions of EVTs via suppression of WNT5A-mediating ROR2/JNK/MMPs pathway, which may eventually contribute to the development of PE.

NOTUM-mediated WNT silencing drives extravillous trophoblast cell lineage development

Trophoblast stem (TS) cells have the unique capacity to differentiate into specialized cell types, including extravillous trophoblast (EVT) cells. EVT cells invade into and transform the uterus where they act to remodel the vasculature facilitating the redirection of maternal nutrients to the developing fetus. Disruptions in EVT cell development and function are at the core of pregnancy-related disease. WNT-activated signal transduction is a conserved regulator of morphogenesis of many organ systems, including the placenta. In human TS cells, activation of canonical WNT signaling is critical for maintenance of the TS cell stem state and its downregulation accompanies EVT cell differentiation. We show that aberrant WNT signaling undermines EVT cell differentiation. Notum, palmitoleoyl-protein carboxylesterase (NOTUM), a negative regulator of canonical WNT signaling, was prominently expressed in first-trimester EVT cells developing in situ and up-regulated in EVT cells derived from human TS cells. Furthermore, NOTUM was required for optimal human TS cell differentiation to EVT cells. Activation of NOTUM in EVT cells is driven, at least in part, by endothelial Per-Arnt-Sim (PAS) domain 1 (also called hypoxia-inducible factor 2 alpha). Collectively, our findings indicate that canonical Wingless-related integration site (WNT) signaling is essential for maintenance of human trophoblast cell stemness and regulation of human TS cell differentiation. Downregulation of canonical WNT signaling via the actions of NOTUM is required for optimal EVT cell differentiation.

Role of circular RNAs in preeclampsia (Review)

Preeclampsia (PE) is a hypertensive disorder of pregnancy characterized by new-onset hypertension and proteinuria after 20 weeks of gestation, which affects 3-8% of pregnant individuals worldwide each year. Prevention, diagnosis and treatment of PE are some of the most important problems faced by obstetrics. There is growing evidence that circular RNAs (circRNAs) are involved in the pathogenesis of PE. The present review summarizes the research progress of circRNAs and then describes the expression patterns of circRNAs in PE and their functional mechanisms affecting PE development. The role of circRNAs as biomarkers for the diagnosis of PE, and the research status of circRNAs in PE are summarized in the hope of finding novel strategies for the prevention and treatment of PE.

NOTUM-MEDIATED WNT SILENCING DRIVES EXTRAVILLOUS TROPHOBLAST CELL LINEAGE DEVELOPMENT

Trophoblast stem (TS) cells have the unique capacity to differentiate into specialized cell types, including extravillous trophoblast (EVT) cells. EVT cells invade into and transform the uterus where they act to remodel the vasculature facilitating the redirection of maternal nutrients to the developing fetus. Disruptions in EVT cell development and function are at the core of pregnancy-related disease. WNT-activated signal transduction is a conserved regulator of morphogenesis of many organ systems, including the placenta. In human TS cells, activation of canonical WNT signaling is critical for maintenance of the TS cell stem state and its downregulation accompanies EVT cell differentiation. We show that aberrant WNT signaling undermines EVT cell differentiation. Notum, palmitoleoyl-protein carboxylesterase (NOTUM), a negative regulator of canonical WNT signaling, was prominently expressed in first trimester EVT cells developing in situ and upregulated in EVT cells derived from human TS cells. Furthermore, NOTUM was required for optimal human TS cell differentiation to EVT cells. Activation of NOTUM in EVT cells is driven, at least in part, by endothelial PAS domain 1 (also called hypoxia-inducible factor 2 alpha). Collectively, our findings indicate that canonical WNT signaling is essential for maintenance of human trophoblast cell stemness and regulation of human TS cell differentiation. Downregulation of canonical WNT signaling via the actions of NOTUM is required for optimal EVT cell differentiation.

Down-regulated Wnt7a and GPR124 in early-onset preeclampsia placentas reduce invasion and migration of trophoblast cells

OBJECTIVES

Preeclampsia (PE) is a disease specific to pregnancy that causes 9-10 % of maternal deaths. Early-onset PE (<34 weeks' gestation) is the most dangerous category of PE. Wnt7a and GPR124 (G protein-coupled receptor 124) are widely expressed in the human reproductive process. Especially during embryogenesis and tumorigenesis, Wnt7a plays a crucial role. However, few studies have examined the association between Wnt7a-GPR124 and early-onset PE. The aim of this study was to examine the significance of Wnt7a and GPR124 in early-onset PE as well as Wnt7a's role in trophoblast cells.

METHODS

Immunohistochemistry (IHC), real-time PCR, and western blotting (WB) were used to investigate Wnt7a and GPR124 expression in normal and early-onset PE placentas. Additionally, FACS, Transwell, and CCK-8 assays were used to diagnose Wnt7a involvement in migration, invasion, and proliferation.

RESULTS

In the early-onset PE group, Wnt7a and GPR124 expression was significantly lower than in the normal group, especially in the area of syncytiotrophoblasts (STBs) and extravillous trophoblasts (EVTs). A negative correlation was found between Wnt7a RNA and GPR124 expression (r=-0.42, p<0.01). However, the Wnt7a RNA expression level was positive correlated with PE severity. In further cellular functional experiments, knockdown of Wnt7a inhibits HTR8/SVeno cells invasion and migration but has little effect on proliferation and apoptosis.

CONCLUSIONS

Through the Wnt pathway, Wnt7a regulates trophoblast cell invasion and migration, and may contribute to early-onset preeclampsia pathogenesis. A molecular level study of Wnt7a will be needed to find downstream proteins and mechanisms of interaction.

circPTK2 promotes proliferation, migration and invasion of trophoblast cells through the miR-619/WNT7B pathway in preeclampsia

It has been shown that the circular RNA (circRNA) circPTK2 modulates many types of diseases. However, the possible functions as well as the molecular mechanisms of circPTK2 in preeclampsia (PE) and their effects on trophoblast are unknown. Herein, we obtained the placental tissues from 20 pregnant women with PE who delivered in the Yueyang Maternal Child Medicine Health Hospital between 2019 and 2021 to serve as the PE group, and a normal group was composed of 20 healthy pregnant women with normal prenatal examinations. The circPTK2 level was significantly reduced in tissues from the PE group. The expression and localization of circPTK2 were verified using RT-qPCR. CircPTK2 silencing inhibited HTR-8/SVneo growth and migration in vitro. To investigate the underlying mechanism of circPTK2 in PE progression, dual-luciferase reporter assays were conducted. It was found that circPTK2 and WNT7B could bind directly to miR-619, and that circPTK2 affected WNT7B expression by sponging miR-619. To conclude, this study identified the functions and mechanisms of the circPTK2/miR-619/WNT7B axis in PE progression. In this way, circPTK2 has the potential to be used both in diagnostic and therapeutic settings for PE.

Exploring maternal-fetal interface with in vitro placental and trophoblastic models

The placenta, being a temporary organ, plays a crucial role in facilitating the exchange of nutrients and gases between the mother and the fetus during pregnancy. Any abnormalities in the development of this vital organ not only lead to various pregnancy-related disorders that can result in fetal injury or death, but also have long-term effects on maternal health. In vitro models have been employed to study the physiological features and molecular regulatory mechanisms of placental development, aiming to gain a detailed understanding of the pathogenesis of pregnancy-related diseases. Among these models, trophoblast stem cell culture and organoids show great promise. In this review, we provide a comprehensive overview of the current mature trophoblast stem cell models and emerging organoid models, while also discussing other models in a systematic manner. We believe that this knowledge will be valuable in guiding further exploration of the complex maternal-fetal interface.

Human Placental LRP5 and Sclerostin are Increased in Gestational Diabetes Mellitus Pregnancies

INTRODUCTION

The low-density lipoprotein receptor-related protein 5 (LRP5) and its inhibitor sclerostin, are key components of bone metabolism and potential contributors to type 2 diabetes mellitus susceptibility. This study aims at evaluating the expression of placental LRP5 and sclerostin in pregnancies with gestational diabetes mellitus (GDM) and investigate possible associations with umbilical sclerostin concentrations and clinical outcomes in mothers and their neonates.

METHODS

Twenty-six GDM-mothers and 34 non-GDM mothers of Caucasian origin and their neonates admitted in a gynecology and obstetrics department of a university hospital were included in this study. Demographic data and maternal fasting glucose concentrations (24-28 weeks of gestation) were retrieved from the patients' medical records. Placental LRP5 was determined by immunohistochemistry (IHC) and Western blotting analysis; placental sclerostin was determined by IHC. Umbilical serum sclerostin concentrations were measured by ELISA.

RESULTS

Placental sclerostin IHC intensity values were positively correlated with LRP5 values as detected either by IHC (r = 0.529; P < .001) or Western blotting (r = 0.398; P = .008), with pregestational maternal body mass index values (r = 0.299; P = .043) and with maternal fasting glucose concentrations (r = 0.475; P = .009). Placental sclerostin and LRP5 were significantly greater in GDM compared with non-GDM placentas (histo-score: 65.08 ± 17.09 vs 11.45 ± 2.33, P < .001; 145.53 ± 43.74 vs 202.88 ± 58.65, P < .001; respectively).

DISCUSSION

Sclerostin and LRP5 were detected in human placentas. The overexpression of placental sclerostin and LRP5 values in GDM compared with non-GDM pregnancies, as well as the positive association of placental sclerostin values with pregestational maternal body mass index and maternal fasting glucose concentrations may indicate the development of an adaptive mechanism in face of maternal hyperglycemia.

Zika virus targets human trophoblast stem cells and prevents syncytialization in placental trophoblast organoids

Zika virus (ZIKV) infection during pregnancy threatens pregnancy and fetal health. However, the infectivity and pathological effects of ZIKV on placental trophoblast progenitor cells in early human embryos remain largely unknown. Here, using human trophoblast stem cells (hTSCs), we demonstrated that hTSCs were permissive to ZIKV infection, and resistance to ZIKV increased with hTSC differentiation. Combining gene knockout and transcriptome analysis, we demonstrated that the intrinsic expression of AXL and TIM-1, and the absence of potent interferon (IFN)-stimulated genes (ISGs) and IFNs contributed to the high sensitivity of hTSCs to ZIKV. Furthermore, using our newly developed hTSC-derived trophoblast organoid (hTSC-organoid), we demonstrated that ZIKV infection disrupted the structure of mature hTSC-organoids and inhibited syncytialization. Single-cell RNA sequencing (scRNA-seq) further demonstrated that ZIKV infection of hTSC-organoids disrupted the stemness of hTSCs and the proliferation of cytotrophoblast cells (CTBs) and probably led to a preeclampsia (PE) phenotype. Overall, our results clearly demonstrate that hTSCs represent the major target cells of ZIKV, and a reduced syncytialization may result from ZIKV infection of early developing placenta. These findings deepen our understanding of the characteristics and consequences of ZIKV infection of hTSCs in early human embryos.

Generating Functional Multicellular Organoids from Human Placenta Villi

The interaction between trophoblasts, stroma cells, and immune cells at the maternal-fetal interface constitutes the functional units of the placenta, which is crucial for successful pregnancy outcomes. However, the investigation of this intricate interplay is restricted due to the absence of efficient experimental models. To address this challenge, a robust, reliable methodology for generating placenta villi organoids (PVOs) from early, late, or diseased pregnancies using air-liquid surface culture is developed. PVOs contain cytotrophoblasts that can self-renew and differentiate directly, along with stromal elements that retain native immune cells. Analysis of scRNA sequencing and WES data reveals that PVOs faithfully recapitulate the cellular components and genetic alterations of the corresponding source tissue. Additionally, PVOs derived from patients with preeclampsia exhibit specific pathological features such as inflammation, antiangiogenic imbalance, and decreased syncytin expression. The PVO-based propagation of primary placenta villi should enable a deeper investigation of placenta development and exploration of the underlying pathogenesis and therapeutics of placenta-originated diseases.

The role of WNT10B in physiology and disease: A 10-year update

WNT10B, a member of the WNT family of secreted glycoproteins, activates the WNT/β-catenin signaling cascade to control proliferation, stemness, pluripotency, and cell fate decisions. WNT10B plays roles in many tissues, including bone, adipocytes, skin, hair, muscle, placenta, and the immune system. Aberrant WNT10B signaling leads to several diseases, such as osteoporosis, obesity, split-hand/foot malformation (SHFM), fibrosis, dental anomalies, and cancer. We reviewed WNT10B a decade ago, and here we provide a comprehensive update to the field. Novel research on WNT10B has expanded to many more tissues and diseases. WNT10B polymorphisms and mutations correlate with many phenotypes, including bone mineral density, obesity, pig litter size, dog elbow dysplasia, and cow body size. In addition, the field has focused on the regulation of WNT10B using upstream mediators, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). We also discussed the therapeutic implications of WNT10B regulation. In summary, research conducted during 2012-2022 revealed several new, diverse functions in the role of WNT10B in physiology and disease.

Gone with the Wnt(less): a mechanistic perspective on the journey of Wnt

Wnts are short-range signaling proteins, expressed in all metazoans from sponges to humans, critical for cell development and fate. There are 19 different Wnts in the human genome with varying expression levels and patterns, and post-translational modifications. Common to essentially all Wnts is the palmitoleation of a conserved serine by the O-acyltransferase PORCN in the endoplasmic reticulum (ER). All lipidated Wnts then bind a dedicated carrier Wntless (WLS), endowed with the task of transporting them from the ER to the plasma membrane, and ultimately facilitating their release to receptors on the Wnt-receiving cell to initiate signaling. Here, we will focus on the WLS-mediated transport step. There are currently two published structures, both obtained by single-particle cryo-electron microscopy of the Wnt/WLS complex: human Wnt8A-bound and human Wnt3A-bound WLS. We analyze the two Wnt/WLS structures - remarkably similar despite the sequence similarity between Wnt8A and Wnt3A being only ∼39% - to begin to understand the conserved nature of this binding mechanism, and ultimately how one carrier can accommodate a family of 19 different Wnts. By comparing how Wnt associates with WLS with how it binds to PORCN and FZD receptors, we can begin to speculate on mechanisms of Wnt transfer from PORCN to WLS, and from WLS to FZD, thus providing molecular-level insight into these essential steps of the Wnt signaling pathway.

How trophoblasts fuse: an in-depth look into placental syncytiotrophoblast formation

In humans, cell fusion is restricted to only a few cell types under normal conditions. In the placenta, cell fusion is a critical process for generating syncytiotrophoblast: the giant multinucleated trophoblast lineage containing billions of nuclei within an interconnected cytoplasm that forms the primary interface separating maternal blood from fetal tissue. The unique morphology of syncytiotrophoblast ensures that nutrients and gases can be efficiently transferred between maternal and fetal tissue while simultaneously restricting entry of potentially damaging substances and maternal immune cells through intercellular junctions. To maintain integrity of the syncytiotrophoblast layer, underlying cytotrophoblast progenitor cells terminate their capability for self-renewal, upregulate expression of genes needed for differentiation, and then fuse into the overlying syncytium. These processes are disrupted in a variety of obstetric complications, underscoring the importance of proper syncytiotrophoblast formation for pregnancy health. Herein, an overview of key mechanisms underlying human trophoblast fusion and syncytiotrophoblast development is discussed.

Wnt4, Wnt6 and β-catenin expression in human placental tissue - is there a link with first trimester miscarriage? Results from a pilot study

BACKGROUND

Demystifying the events around early pregnancy is challenging. A wide network of mediators and signaling cascades orchestrate the processes of implantation and trophoblast proliferation. Dysregulation of these pathways could be implicated in early pregnancy loss. There is accumulating evidence around the role of Wnt pathway in implantation and early pregnancy. The purpose of this study was to explore alterations in the expression of Wnt4, Wnt6 and β-catenin in placental tissue obtained from human first trimester euploid miscarriages versus normally developing early pregnancies.

METHODS

The study group consisted of first trimester miscarriages (early embryonic demises and incomplete miscarriages) and the control group of social terminations of pregnancy (TOPs). The placental mRNA expression of Wnt4, Wnt6 and β-catenin was studied using reverse transcription PCR and real time PCR. Only euploid conceptions were included in the analysis.

RESULTS

Wnt4 expression was significantly increased in placental tissue from first trimester miscarriages versus controls (p = 0.003). No significant difference was documented in the expression of Wnt6 (p = 0.286) and β-catenin (p = 0.793). There was a 5.1fold increase in Wnt4 expression for early embryonic demises versus TOPs and a 7.6fold increase for incomplete miscarriages versus TOPs - no significant difference between the two subgroups of miscarriage (p = 0.533).

CONCLUSIONS

This is, to our knowledge, the first study demonstrating significant alteration of Wnt4 expression in human placental tissue, from failed early pregnancies compared to normal controls. Undoubtedly, a more profound study is needed to confirm these preliminary findings and explore Wnt mediators as potential targets for strategies to predict and prevent miscarriage.

Modulation of Telocytes in Women with Preeclampsia: A Prospective Comparative Study

Background

Telocytes (TCs) are networking cells with enigmatic functions. Placenta is a noninnervated organ with the TCs could have function of signal transmission to placental myofibroblasts, being likely a regulator for maternal blood flow. Preeclampsia (PE) is a disease complicating the second half of pregnancy associated with hypoxia probably due to failure of vascular remodeling of spiral arteries resulting in poor placental perfusion. We hypothesized that disturbance in the morphology of TCs may have a role in the pathogenesis of PE.

Materials and Methods

Women with normal or physiological pregnancy (Group I; 15 women) and with PE (Group II; 15 women) participated in this study. Specimens were obtained from the central cotyledons and the superficial myometrium beneath the implantation sites processed for light microscopy and stained with Hematoxylin and Eosin, toluidine blue, masson trichrome, and CD117.

Results

The villi of group II has thick-walled blood vessels with increased peri-villous fibrinoid deposition, reduced areas of vasculosyncytial membrane and apparent increase in connective tissue density. Morphometric study and statistical analysis revealed a significant increase in the mean number of syncytial knots and significant decrease in placental (villous and decidual) and myometrial TCs and extravillous trophoblasts (EVTs) beneath the placental implantation site in Group II (P < 0.011) in comparison with group I.

Conclusions

PE is associated with significantly low number of placental TCs interestingly with low number of EVTs. Further studies are needed to support our findings.

WNT and NOTCH signaling in human trophoblast development and differentiation

Correct development of the human placenta and its differentiated epithelial cells, syncytial trophoblasts (STBs) and extravillous trophoblasts (EVTs), is crucial for a successful pregnancy outcome. STBs develop by cell fusion of mononuclear cytotrophoblasts (CTBs) in placental floating villi, whereas migratory EVTs originate from specialized villi anchoring to the maternal decidua. Defects in trophoblast differentiation have been associated with severe pregnancy disorders such as early-onset preeclampsia and fetal growth restriction. However, the evolutionary pathways underlying normal and adverse placentation are poorly understood. Herein, we discuss Wingless (WNT) and NOTCH signaling, two pathways that play pivotal roles in human placenta and trophoblast development. Whereas WNT is necessary for expansion of trophoblast progenitors and stem cells, NOTCH1 is required for proliferation and survival of EVT precursors. Differentiation of the latter is orchestrated by a switch in NOTCH receptor expression as well as by changes in WNT ligands and their downstream effectors.

Comparison of Maternal Serum Levels and Placental mRNA Levels of Dickkopf-1 in Preeclamptic and Normal Pregnant Women at Delivery

Background Preeclampsia remains a major cause of perinatal and maternal mortality and morbidity worldwide. Wnt/β-catenin signaling is known to be critically involved in placenta development processes. Dickkopf-1 (DKK1) is a key regulator of this transduction pathway. The aim of this study is to compare maternal serum DKK1 levels and placental mRNA levels of DKK1 and β-catenin in preeclamptic and normal pregnant women at delivery.

Methods The present study included 30 women with preeclampsia and 30 women with normal pregnancy. Maternal serum DKK1 levels were measured by ELISA. Placental mRNA levels of DKK1 and β-catenin were detected using RT-PCR.

Results Decreased maternal serum DKK1 levels were associated with worse maternal and fetal complications including HELLP syndrome, determination of one or more pathological symptom and IUGR diagnosis. No significant difference in maternal serum DKK1 levels was reported between preeclamptic women and women with normal pregnancy. Placental mRNA DKK1 levels were lower in preeclamptic women compared with normal pregnant women. Placental mRNA β-catenin levels showed no significant difference between two groups.

Conclusions Our findings reported the aberrant placental mRNA DKK1 levels in patients with preeclampsia. In addition, worse preeclampsia features were associated with decreased maternal serum DKK1 levels. Hence, aberrant Wnt/β-catenin signaling might present a plausible mechanism in preeclampsia pathogenicity. Dysregulated expression of DKK1 at gene level in the placenta but not at protein level in the maternal serum might confirm the notion that preeclampsia is a type of placenta-derived disease.

WNT3 hypomethylation counteracts low activity of the Wnt signaling pathway in the placenta of preeclampsia

Preeclampsia is a hypertensive disorder of pregnancy. Many studies have shown that epigenetic mechanisms may play a role in preeclampsia. Moreover, our previous study indicated that the differentially methylated genes in preeclampsia were enriched in the Wnt/β-catenin signaling pathway. This study aimed to identify differentially methylated Wnt/β-catenin signaling pathway genes in the preeclamptic placenta and to study the roles of these genes in trophoblast cells in vitro. Using an Illumina Infinium HumanMethylation 850 K BeadChip, we found that the Wnt signaling pathway was globally hypermethylated in the preeclamptic group compared with the term birth group, but hypomethylated in the preeclamptic group compared with the preterm birth group. Among all Wnt/β-catenin signaling pathway factors, WNT3 was the most significantly differentially expressed gene and was hypomethylated in the preeclamptic group compared to the nonhypertensive groups, namely, the preterm birth group and term birth group. This result was confirmed by pyrosequencing. Through quantitative real-time PCR and western blot analysis, the WNT3 gene was found to be highly expressed in preeclamptic placental tissues, in contrast to other WNT factors, which were previously reported to be expressed at low levels in placental tissues. Additionally, in the HTR8/SVneo cell line, knockdown of WNT3 suppressed the Wnt/β-catenin signaling pathway, consistent with the findings for other WNT factors. These results prompted us to speculate that the WNT3 gene counteracts the low activation state of the Wnt signaling pathway in the preeclamptic placenta through methylation modification.

Cumulus cells of euploid versus whole chromosome 21 aneuploid embryos reveal differentially expressed genes

RESEARCH QUESTION

Can cumulus cells be used as a non-invasive target for the study of determinants of preimplantation embryo quality?

DESIGN

Cumulus cells were collected from monosomy 21, trisomy 21 and euploid embryos and subjected to RNA sequencing analysis and real-time polymerase chain reaction assays. The differential gene expression was analysed for different comparisons.

RESULTS

A total of 3122 genes in monosomy 21 cumulus cells and 19 genes in trisomy 21 cumulus cells were differentially expressed compared with euploid cumulus cells. Thirteen of these genes were differentially expressed in both monosomy and trisomy 21, compared with euploid, including disheveled segment polarity protein 2 (DVL2), cellular communication network factor 1 (CCN1/CYR61) and serum response factor (SRF), which have been previously implicated in embryo developmental competence. In addition, ingenuity pathway analysis revealed cell-cell contact function to be affected in both monosomy and trisomy 21 cumulus cells.

CONCLUSIONS

These findings support the use of cumulus cell gene expression analysis for the development of biomarkers evaluating oocyte quality for patients undergoing fertility preservation of oocytes.

Dissecting human trophoblast cell transcriptional heterogeneity in preeclampsia using single-cell RNA sequencing

Objective

PE is a pregnancy‐specific syndrome that affects 3%–5% of pregnant women. It often presents as new‐onset hypertension and proteinuria during the third trimester. PE progresses rapidly and may lead to serious complications, including the death of both mother and fetus. In low‐income countries, PE is one of the main causes of maternal and child mortality. While the cause of PE is still debated, clinical and pathological studies suggest that the placenta plays an important role in the pathogenesis of PE.

Materials and Methods

In this single‐cell RNA‐sequencing (RNA‐seq) study, the placenta was taken from the designated position after cesarean section. We compared placental cell subsets and their transcriptional heterogeneity between preeclampsia and healthy pregnancies using the single‐cell RNA‐seq technology. A developmental trajectory of human trophoblasts was shown.

Results

Gene expression in endoplasmic reticulum signaling pathways in syncytiotrophoblast was upregulated in the PE group. The villi cytotrophoblasts (VCT) and extravillous trophoblasts were mainly involved in immune responses.

Conclusion

The placental immune function of patients with PE was altered. Proteasomes, spliceosomes, ribosomes, and mitochondria were abnormally active in the new VCT cell type.

Placental Angiogenesis in Mammals: A Review of the Regulatory Effects of Signaling Pathways and Functional Nutrients

Normal placental development and proper angiogenesis are essential for fetal growth during pregnancy. Angiogenesis involves the regulatory action of many angiogenic factors and a series of signal transduction processes inside and outside the cell. The obstruction of placental angiogenesis causes fetal growth restriction and serious pregnancy complications, even leading to fetal loss and pregnancy cessation. In this review, the effects of placental angiogenesis on fetal development are described, and several signaling pathways related to placental angiogenesis and their key regulatory mediators are summarized. These factors, which include vascular endothelial growth factor (VEGF)-VEGF receptor, delta-like ligand 4 (DLL-4)-Notch, Wnt, and Hedgehog, may affect the placental angiogenesis process. Moreover, the degree of vascularization depends on cell proliferation, migration, and differentiation, which is affected by the synthesis and secretion of metabolites or intermediates and mutual coordination or inhibition in these pathways. Furthermore, we discuss recent advances regarding the role of functional nutrients (including amino acids and fatty acids) in regulating placental angiogenesis. Understanding the specific mechanism of placental angiogenesis and its influence on fetal development may facilitate the establishment of new therapeutic strategies for the treatment of preterm birth, pre-eclampsia, or intrauterine growth restriction, and provide a theoretical basis for formulating nutritional regulation strategies during pregnancy.

CTHRC1 promotes growth, migration and invasion of trophoblasts via reciprocal Wnt/β-catenin regulation

Preeclampsia (PE) is a pregnancy complication that is characterized by high blood pressure and is associated with high maternal and fetal morbidities. At a mechanistic level, PE is characterized by reduced invasion ability of trophoblasts. Collagen triple helix repeat containing-1 (CTHRC1) is a well-known tumor-promoting factor in several malignant tumors, but its role in trophoblasts remains unknown. In this study, we characterized the expression of CTHRC1 in placenta tissue samples from PE pregnancies and from normal pregnancies. We used the trophoblasts cell lines HTR-8/SVneo and JEG-3 to investigate the role of CTHRC1 in cell migration, invasion and proliferation. Western blot, PCR and TOP/FOP luciferase activity assays were used to investigate the molecular mechanisms underlying these cell behaviors. Placenta tissue samples obtained from pregnant women with PE expressed lower levels of CTHRC1 than those of placenta tissues from women with normal pregnancies. Down-regulation of CTHRC1 impaired cell proliferation, migration and invasion of trophoblasts, while CTHRC1 overexpression promoted nuclear translocation of β-catenin, a result that was further confirmed by TOP/FOP luciferase activity assay. Our findings suggest that CTHRC1 promotes migration and invasion of trophoblasts via reciprocal Wnt/β-catenin signaling pathway. Down-regulation of CTHRC1 may be a potential mechanism underpinning the development of preeclampsia.

Long noncoding RNA expression profiling identifies MIR210HG as a novel molecule in severe preeclampsia

OBJECTIVE

Preeclampsia (PE) is a potentially fatal pregnancy-specific complication. Nevertheless, the pathogenesis of PE remains indistinct. Recently, increasing studies emphasized that long noncoding RNAs (lncRNAs) functions as imperative regulators in PE. The aim of this study was to compare the lncRNAs transcript profile of placentae in early onset severe preeclampsia (EOSP) with lncRNAs in normal pregnancy (NP) and to evaluate the role of lncRNA MIR210HG (microRNA 210 host gene) in the PE pathogenesis.

METHODS

Using RNA sequencing, we compared transcriptome profiles of placentae in EOSP (n = 3) and NP (n = 3). Bioinformatic tools were used to predict the function of differentially expressed genes while qRT-PCR was used to verify RNA sequencing data. The role of MIR210HG in HTR8/SVneo migration and invasion were analyzed by in vitro MIR210HG gene overexpression.

RESULTS

Our results showed that 527 lncRNAs and 600 mRNAs were differentially expressed in placental samples of EOSP, and the analysis identified 63 key EOSP related genes. As indicated by bioinformatics analyses, lncRNA MIR210HG was a potential pathogenic marker of PE. LncRNA-MIR210HG expression was upregulated in placental samples of PE and enriched in the canonical Wnt signalling pathway. MiR210HG overexpression inhibited HTR8/SVneo cell migration and invasion in vitro. Additionally, miR210HG upregulated dickkopf-1 expression via the sponging of microRNA-520a-3p (miR-520a-3p), thus repressing trophoblast migration and invasion.

CONCLUSION

Our study showed that MiR210HG is a novel upregulated lncRNA in the placentas of PE and MiR210HG regulates the migration and invasive potential of HTR-8/SVneo cell by targeting the miR-520a-3p/Dickkopf-1 axis.

Cyclin G2 upregulation impairs migration, invasion, and network formation through RNF123/Dvl2/JNK signaling in the trophoblast cell line HTR8/SVneo, a possible role in preeclampsia

Disruption of extravillous trophoblast (EVT) migration and invasion is considered to be responsible for pathological placentation in preeclampsia (PE). Cyclin G2 (CCNG2) is an atypical cyclin that inhibits cell cycle progression. However, its biological function and underlying molecular mechanism in PE are poorly understood. In this study, clinical data demonstrated that CCNG2 was significantly upregulated in PE placenta and associated with invasive EVT dysfunction. Additionally, Ccng2 knockout led to an attenuation of PE-like symptoms in the PE mouse model produced via treatment with NG-nitro-L-arginine methyl ester (L-NAME). In vitro, CCNG2 inhibited the migration, invasion, and endothelial-like network formation of human trophoblast cell line HTR8/SVneo. Mechanically, CCNG2 suppressed JNK-dependent Wnt/PCP signaling and its downstream indicators including epithelial-to-mesenchymal transition (EMT) markers and matrix metalloproteinases (MMPs) via promoting the polyubiquitination degradation of dishevelled 2 (Dvl2) protein in HTR8/SVneo cells. We also discovered that the E3 ligase Ring finger protein 123 (RNF123), as a novel CCNG2 target among HTR8/SVneo cells, interacted with Dvl2 and participated in CCNG2-induced polyubiquitination degradation of Dvl2. Moreover, we verified that the treatment of HTR8/SVneo cells with RNF123-specific siRNA improved polyubiquitination-induced degradation of Dvl2 and the activity of Wnt/PCP-JNK signaling mediated by CCNG2. Taken together, our results reveal that the CCNG2/RNF123/Dvl2/JNK axis may be involved in the pathogenesis and progression of PE through trophoblastic cell function modulation, thus probably providing us with new therapeutic strategies for PE treatment.

PAR1&2 driven placenta EVT invasion act via LRP5/6 as coreceptors

While the involvement of protease-activated receptors (PARs) in the physiological regulation of human placenta development, as in tumor biology, is recognized, the molecular pathway is unknown. We evaluated the impact of PAR₁ and PAR₂ function in cytotrophoblast (CTB) proliferation and invasion in a system of extravillous trophoblast (EVT) organ culture and in human cell-lines. Activation of PAR₁ - and PAR₂ -induced EVT invasion and proliferation, while the shRNA silencing of low-density lipoprotein receptor-related protein 5/6 (LRP5/6) inhibited these processes. PAR₁ and PAR₂ effectively induce β-catenin stabilization in a manner similar to that shown for the canonical β-catenin stabilization pathway yet independent of Wnts. Immunoprecipitation analyses and protein-protein docking demonstrated the co-association between either PAR₁ or PAR₂ with LRP5/6 forming an axis of PAR-LRP5/6-Axin. Noticeably, in PAR₁ -PAR₂ heterodimers a dominant role is assigned to PAR₂ over PAR₁ as shown by inhibition of PAR₁ -induced β-catenin levels, and Dvl nuclear localization. This inhibition takes place either by shRNA silenced hPar2 or in the presence of a TrPAR₂ devoid its cytoplasmic tail. Indeed, TrPAR₂ cannot form the PAR₁ -PAR₂ complex, obstructing thereby the flow of signals downstream. Elucidation of the mechanism of PAR-induced invasion contributes to therapeutic options highlighting key partners in the process.

Differentially expressed circular RNAs and the competing endogenous RNA network associated with preeclampsia

INTRODUCTION

Circular RNAs (circRNAs) are non-coding RNAs that are implicated in preeclampsia (PE) pathogenesis; however, their expression and functions in PE remain unclear. In this study, we aimed to investigate the expression of circRNAs in PE and construct a competing endogenous RNA (ceRNA) network, and analyze the associated pathways in PE pathogenesis.

METHODS

We performed circRNA sequencing to identify the differential expression profile of circRNAs in PE as compared to normal pregnancy. The circRNA candidates were validated using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Subsequently, we used datasets from the GEO database to generate the interaction network between circRNAs, microRNAs (miRNAs), and mRNAs. GO and KEGG enrichment analyses were performed to understand the functional significance of the differentially expressed circRNAs in PE.

RESULTS

We identified 361 differentially expressed circRNAs (252 upregulated and 109 downregulated) in preeclamptic placentas. Within the selected 31 circRNAs, 6 of them were verified by qRT-PCR. GO and KEGG analyses revealed the potential pathways affected by these circRNAs, e.g., T cell receptor signaling and MAP kinase pathways. A total of 134 miRNAs and 199 mRNAs were revealed to be differentially expressed in PE by analyzing datasets from the GEO database. The circRNA-miRNA-mRNA network comprised 206 circRNAs, 50 miRNAs, and 38 mRNAs. KEGG analysis of the 38 mRNAs included pathways involved in AMPK and PI3K-Akt signaling.

DISCUSSION

Our results reported the differential expression profile of circRNAs and the circRNA-miRNA-mRNA network in PE, which provides potential therapeutic targets for this disease.

Macrophage-stimulating protein is decreased in severe preeclampsia and regulates the biological behavior of HTR-8/SVneo trophoblast cells

Preeclampsia (PE) is a major challenge for obstetricians. There is no effective way to block the development of PE other than terminating the pregnancy. The biological behavior of trophoblast cells, which are similar to cancer cells, may be closely related to the onset of PE. The vital role of macrophage-stimulating protein (MSP) in the development and progression of cancer has been recognized, while a role for this protein in PE has rarely been reported. This study aimed to explore whether MSP affects severe PE (sPE) and, if so, to characterize the mechanism. Patient information, blood samples and/or placental tissues were collected. An enzyme-linked immunosorbent assay (ELISA) was used to determine the plasma MSP concentration. The relationships between the plasma MSP concentration and clinical characteristics were analyzed. Immunofluorescence was performed to localize MSP in placental tissues. Western blotting and reverse transcription quantitative polymerase chain reaction (RT-qPCR) were used to determine MSP protein and mRNA expression in placental tissues. MSP was overexpressed or underexpressed in the trophoblastic cell line HTR-8/SVneo by lentiviral transfection and the proliferation, apoptosis, migration, invasion and angiogenesis of cells were detected. MSP was downregulated in sPE, and the underexpression of MSP inhibited HTR-8/SVneo cell proliferation, migration, invasion and angiogenesis. We further verified that MSP affects the biological behavior of trophoblast cells through the β-catenin/ZEB1 signaling pathway. These results suggest that decreased MSP in the blood and placental tissues of patients with sPE, especially those with early-onset sPE, leads to reduced trophoblast cell invasion, which plays an important role in the pathogenesis of PE.

Establishment and differentiation of long-term trophoblast organoid cultures from the human placenta

The human placenta is essential for successful reproduction. There is great variation in the anatomy and development of the placenta in different species, meaning that animal models provide limited information about human placental development and function. Until recently, it has been impossible to isolate trophoblast cells from the human placenta that proliferate in vitro. This has limited our ability to understand pregnancy disorders. Generating an in vitro model that recapitulates the unique features of the human placenta has been challenging. The first in vitro model system of human trophoblast that could be cultured long term and differentiated to syncytiotrophoblast (SCT) and extravillous trophoblast (EVT) was a two-dimensional (2D) culture system of human trophoblast stem cells. Here, we describe a protocol to isolate trophoblast from first-trimester human placentas that can be grown long term in a three-dimensional (3D) organoid culture system. Trophoblast organoids can be established within 2-3 weeks, passaged every 7-10 d, and cultured for over a year. The structural organization of these human trophoblast organoids closely resembles the villous placenta with a layer of cytotrophoblast (VCT) that differentiates into superimposed SCT. Altering the composition of the medium leads to differentiation of the trophoblast organoids into HLA-G+ EVT cells which rapidly migrate and invade through the Matrigel droplet in which they are cultured. Our previous research confirmed that there is similarity between the trophoblast organoids and in vivo placentas in their transcriptomes and ability to produce placental hormones. This organoid culture system provides an experimental model to investigate human placental development and function as well as interactions of trophoblast cells with the local and systemic maternal environment.

Development of the human placenta

The placenta is essential for normal in utero development in mammals. In humans, defective placental formation underpins common pregnancy disorders such as pre-eclampsia and fetal growth restriction. The great variation in placental types across mammals means that animal models have been of limited use in understanding human placental development. However, new tools for studying human placental development, including 3D organoids, stem cell culture systems and single cell RNA sequencing, have brought new insights into this field. Here, we review the morphological, molecular and functional aspects of human placental formation, with a focus on the defining cell of the placenta - the trophoblast.

Extravillous trophoblast invasion accelerated by WNT3A, 5A, and 10B via CD44

INTRODUCTION

Appropriate extravillous trophoblast (EVT) invasion is essential for successful pregnancy. Previously, we showed that EVTs express CD44, which accelerated EVT invasion. However, its regulation mechanism via CD44 remains unknown. Our hypothesis was that WNT signaling enhanced EVT invasion via CD44. To test this hypothesis, we investigated the effects of WNT ligands on CD44 expression and EVT invasion using EVT cell lines and isolated primary EVTs.

METHODS

We used EVT cell lines (HTR8/SVneo and HChEpC1b) and isolated primary EVTs, extracted from first-trimester trophoblasts. The cells were supplemented with WNT3A, 5A, and 10B. We examined cell invasion and the expressions of CD44 and matrix metalloproteinase (MMP) 9. Next, to clarify the pathway of WNT10B in EVTs, we knock-downed WNT10B using siRNA and activated or inhibited the WNT canonical pathway using an activator (lithium chloride) or inhibitor (FH535, XAV939) with WNT10B addition.

RESULTS

WNT3A, 5A, and 10B accelerated the invasion in the EVT lines and isolated primary EVTs. The expressions of CD44 and MMP9 were also upregulated by WNT ligands. WNT10B knockdown significantly inhibited EVT invasion concomitantly with CD44 expression. The WNT canonical pathway activator upregulated CD44 expression and its inhibitor downregulated it with WNT10B addition.

CONCLUSIONS

The present study is the first to show the possibility that WNT3A, WNT5A, and WNT10B exist upstream of CD44 in EVTs. Among them, WNT10B may be a novel accelerator of EVT invasion. WNT signaling mediated by multiple WNT ligands may contribute to EVT invasion.

LIN28-let-7 axis regulates genes in immortalized human trophoblast cells by targeting the ARID3B-complex

Abnormal placental development is one of the main etiological factors for intrauterine growth restriction (IUGR). Here, we show that LIN28A and LIN28B are significantly lower and lethal-7 (let-7) microRNAs (miRNAs) significantly higher in term human IUGR vs. normal placentas. We hypothesize that let-7 miRNAs regulate genes with known importance for human placental development [high-mobility group AT-hook 1 (HMGA1), transcriptional regulator Myc-like (c-myc), vascular endothelial growth factor A (VEGF-A), and Wnt family member 1 (WNT1)] by targeting the AT-rich interacting domain (ARID)-3B complex. ACH-3P cells with LIN28A and LIN28B knockout (DKOs) significantly increased let-7 miRNAs, leading to significantly decreased ARID3A, ARID3B, and lysine demethylase 4C (KDM4C). Similarly, Sw.71 cells overexpressing LIN28A and LIN28B (DKIs) significantly decreased let-7 miRNAs, leading to significantly increased ARID3A, ARID3B, and KDM4C. In ACH-3P cells, ARID3A, ARID3B, and KDM4C make a triprotein complex [triprotein complex comprising ARID3A, ARID3B, and KDM4C (ARID3B-complex)] that binds the promoter regions of HMGA1, c-MYC, VEGF-A, and WNT1. ARID3B knockout in ACH-3P cells disrupted the ARID3B-complex, leading to a significant decrease in HMGA1, c-MYC, VEGF-A, and WNT1. DKOs had a significant reduction, whereas DKIs had a significant increase in HMGA1, c-MYC, VEGF-A, and WNT1, potentially due to regulation by the ARID3B-complex. This is the first study showing regulation of let-7 targets in immortalized human trophoblast cells by the ARID3B-complex.-Ali, A., Anthony, R. V., Bouma, G. J., Winger, Q. A. LIN28-let-7 axis regulates genes in immortalized human trophoblast cells by targeting the ARID3B-complex.

Trophoblast organoids as a model for maternal-fetal interactions during human placentation

The placenta is the extraembryonic organ that supports the fetus during intrauterine life. Although placental dysfunction results in major disorders of pregnancy with immediate and lifelong consequences for the mother and child, our knowledge of the human placenta is limited owing to a lack of functional experimental models1. After implantation, the trophectoderm of the blastocyst rapidly proliferates and generates the trophoblast, the unique cell type of the placenta. In vivo, proliferative villous cytotrophoblast cells differentiate into two main sub-populations: syncytiotrophoblast, the multinucleated epithelium of the villi responsible for nutrient exchange and hormone production, and extravillous trophoblast cells, which anchor the placenta to the maternal decidua and transform the maternal spiral arteries2. Here we describe the generation of long-term, genetically stable organoid cultures of trophoblast that can differentiate into both syncytiotrophoblast and extravillous trophoblast. We used human leukocyte antigen (HLA) typing to confirm that the organoids were derived from the fetus, and verified their identities against four trophoblast-specific criteria3. The cultures organize into villous-like structures, and we detected the secretion of placental-specific peptides and hormones, including human chorionic gonadotropin (hCG), growth differentiation factor 15 (GDF15) and pregnancy-specific glycoprotein (PSG) by mass spectrometry. The organoids also differentiate into HLA-G+ extravillous trophoblast cells, which vigorously invade in three-dimensional cultures. Analysis of the methylome reveals that the organoids closely resemble normal first trimester placentas. This organoid model will be transformative for studying human placental development and for investigating trophoblast interactions with the local and systemic maternal environment.

Regulation of Placental Extravillous Trophoblasts by the Maternal Uterine Environment

During placentation invasive extravillous trophoblasts (EVTs) migrate into the maternal uterus and modify its vessels. In particular, remodeling of the spiral arteries by EVTs is critical for adapting blood flow and nutrient transport to the developing fetus. Failures in this process have been noticed in different pregnancy complications such as preeclampsia, intrauterine growth restriction, stillbirth, or recurrent abortion. Upon invasion into the decidua, the endometrium of pregnancy, EVTs encounter different maternal cell types such as decidual macrophages, uterine NK (uNK) cells and stromal cells expressing a plethora of growth factors and cytokines. Here, we will summarize development of the EVT lineage, a process occurring independently of the uterine environment, and formation of its different subtypes. Further, we will discuss interactions of EVTs with arteries, veins and lymphatics and illustrate how the decidua and its different immune cells regulate EVT differentiation, invasion and survival. The present literature suggests that the decidual environment and its soluble factors critically modulate EVT function and reproductive success.

Self-Renewing Trophoblast Organoids Recapitulate the Developmental Program of the Early Human Placenta

Defective placentation is the underlying cause of various pregnancy complications, such as severe intrauterine growth restriction and preeclampsia. However, studies on human placental development are hampered by the lack of a self-renewing in vitro model that would recapitulate formation of trophoblast progenitors and differentiated subtypes, syncytiotrophoblast (STB) and invasive extravillous trophoblast (EVT), in a 3D orientation. Hence, we established long-term expanding organoid cultures from purified first-trimester cytotrophoblasts (CTBs). Molecular analyses revealed that the CTB organoid cultures (CTB-ORGs) express markers of trophoblast stemness and proliferation and are highly similar to primary CTBs at the level of global gene expression. Whereas CTB-ORGs spontaneously generated STBs, withdrawal of factors for self-renewal induced trophoblast outgrowth, expressing the EVT progenitor marker NOTCH1, and provoked formation of adjacent, distally located HLA-G⁺ EVTs. In summary, we established human CTB-ORGs that grow and differentiate under defined culture conditions, allowing future human placental disease modeling.

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Derivation of cytotrophoblast organoids from human placenta

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Long-term expansion of trophoblast organoids in a chemically defined medium

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Formation of the extravillous trophoblast lineage under defined culture conditions

Impaired Wnt5a signaling in extravillous trophoblasts: Relevance to poor placentation in early gestation and subsequent preeclampsia

BACKGROUND

Defective decidual endovascular trophoblast invasion and subsequent impaired spiral artery remodeling is highly associated with the pathogenesis of preeclampsia (PE). Since there are scant and conflicting data regarding the function of Wnt5a signaling in extravillous trophoblasts (EVT), the aim of this study was to investigate whethere impaired Wnt5a signaling affects the invasive and tube forming capabilities of EVT.

METHODS

Expression levels of Wnt ligands were compared between first trimester chorionic villi of women who later developed PE and women with unaffected pregnancies using publicly available microarray data (GSE12767). Wnt5a expression was examined in placentas using quantitative RT-PCR, Western blot analysis and immunohistochemistry. The function of Wnt5a signaling in EVT was investigated in an immortalized first trimester EVT cell line, HTR-8/SVneo, using small-interfering RNAs, recombinant human Wnt5a (rhWnt5a), and inhibitors of JNK or PKC.

RESULTS

Microarray data analysis of the first trimester placentas showed that, among Wnt ligands, Wnt5a expression was significantly lower in women who later developed PE. The mRNA and protein expression levels of Wnt5a were significantly decreased in PE placentas compared with normal term placentas. Wnt5a knockdown significantly suppressed invasion and tube formation of HTR-8/SVneo cells, while the addition of rhWnt5a augmented the cell migration, invasion, and tube formation. Repression of Wnt5a/PKC signaling in HTR-8/SVneo cells inhibited cell invasion, but did not alter cell tube formation. In contrast, inhibition of Wnt5a/JNK signaling attenuated rhWnt5a-induced invasion and tube formation capabilities.

CONCLUSIONS

These findings suggest that impaired Wnt5a signaling is associated with poor placentation and subsequent PE.

Activation of β-catenin causes defects in embryonic development during maternal-to-zygotic transition in mice

The early stage of embryogenesis is an important and complex cell-remodeling event in reproductive biology. To develop into a normal zygote, maternal-to-zygotic transition (MZT) is especially important for both zygotic genome activation (ZGA) and degradation of maternal products during the early stage of embryonic development. β-Catenin has been identified as an important regulator of embryonic development and adult stem cell division via the canonical Wnt/β-catenin signalling pathway. However, the role of activated β-catenin during MZT remains elusive. In the present study, we found that β-catenin is mainly expressed during embryogenesis in the cell membrane from the zygote- to morula-stage embryos but not in MII oocytes. To analyze the function of activated β-catenin during MZT, we conducted a β-catenin activation assay during embryogenesis. Our results indicated that development beyond the two-cell stage was inhibited in zygotes with β-catenin activation. Further analysis showed that activated form of β-catenin protein was increased and the phosphorylated form of β-catenin protein was decreased in culture embryos. Taken together, our study reveals that activation of β-catenin may play a vital role in zygotic development, determining the developmental potential of mouse embryos.

Decreased expression of WNT2 in villi of unexplained recurrent spontaneous abortion patients may cause trophoblast cell dysfunction via downregulated Wnt/β-catenin signaling pathway

WNT2 has been reported to be important for placental development, especially for the proper vascularization of the placenta. However, its precise role in first-trimester trophoblast cells is still unknown. WNT2 expression in the villous tissues of unexplained recurrent spontaneous abortion (URSA) patients was compared with that of healthy women by Western blot. The function of WNT2 in HTR-8/SVneo trophoblast cells was evaluated by altering the cellular WNT2 level through overexpression and shRNA knockdown. The molecular mechanism of the effect of WNT2 on trophoblast cells was investigated. The association of WNT2 with the Wnt/β-catenin signaling pathway was studied through Western blot and immunofluorescence. Results showed that WNT2 protein expression was significantly decreased in villi of the URSA group compared with the control group. In vitro studies showed that WNT2 could promote human trophoblast cell proliferation and migration through activating the Wnt/β-catenin signaling pathway. Moreover, upon the knockdown of WNT2, trophoblast cell proliferation and migration were significantly suppressed. In conclusion, our study indicated that WNT2 plays an important role in trophoblast function. WNT2 insufficiency might cause impaired trophoblast cell proliferation and migration via downregulation of Wnt/β-catenin signaling pathway.

Wnt/β-catenin signaling pathway in severe preeclampsia

This study aims to elucidate the mechanisms of Wnt/β-catenin signaling pathway in the development of preeclampsia (PE). The mRNA levels of Wnt1, β-catenin, c-myc and cyclinD1 were determined by real-time PCR in the placentas. Moreover, the expression levels of Wnt1, β-catenin, Dickkopf-1 (DKK1) and glycogen synthase kinase 3β (GSK-3β) proteins were detected by Western blot. Immunohistochemistry was used in placental tissue microarray to localize the expression of Wnt1, β-catenin, DKK1 proteins in the placentas of two groups. Compared with the control placentas, the mRNA levels of Wnt1, β-catenin, c-myc and cyclinD1 were decreased in the severe preeclamptic placentas. The Western blot results showed that the expression levels of Wnt1, β-catenin, and GSK-3β proteins were significantly elevated in the control group, while the expression level of DKK1 was significantly decreased. In addition, the staining intensity of Wnt1, β-catenin were weaker in the placentas of the severe PE group while the staining intensity of DKK1 was significantly stronger in the placentas of the severe PE group. Wnt/β-catenin signaling pathway may play a significant role in the pathogenesis of PE by regulating the invasion and proliferation of trophoblast.

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.

Wnt/β-catenin signaling pathway in trophoblasts and abnormal activation in preeclampsia (Review)

Preeclampsia (PE) is one of the most common types of hypertensive disease and occurs in 3‑4% of pregnancies. There are a number of theories on the pathogenesis of PE. Abnormal differentiation of the placenta may lead to failure of trophoblast migration, shallow placenta implantation and placental ischemia/hypoxia, followed by the subsequent occurrence of PE. The Wnt/β-catenin pathway is a canonical Wnt‑signaling pathway that regulates several biological processes, including proliferation, migration, invasion and apoptosis. Abnormal activation of the Wnt/β‑catenin signaling pathway may serve an important role in the pathogenesis of various human diseases, particularly in human cancer. Recent studies have demonstrated that the dysregulation of the Wnt/β‑catenin signaling pathway may contribute to PE. The present review aims to summarize the articles on Wnt/β‑catenin signaling pathway in the trophoblast and abnormal activation in PE. Wnt/β-catenin signaling may serve a significant role in the pathogenesis of PE and may be a prospective therapeutic target for the prevention and treatment of PE.

Transcriptional Dynamics of Cultured Human Villous Cytotrophoblasts

During human pregnancy, cytotrophoblasts (CTBs) play key roles in uterine invasion, vascular remodeling, and anchoring of the feto-placental unit. Due to the challenges associated with studying human placentation in utero, cultured primary villous CTBs are used as a model of the differentiation pathway that leads to invasion of the uterine wall. In vitro, CTBs emulate in vivo cell behaviors, such as migration, aggregation, and substrate penetration. Although some of the molecular features related to these cell behaviors have been described, the underlying mechanisms, at a global level, remain undefined at midgestation. Thus, in this study, we characterized second-trimester CTB differentiation/invasion in vitro, correlating the major morphological transitions with the transcriptional changes that occurred at these steps. After plating on Matrigel as individual cells, CTBs migrated toward each other and formed multicellular aggregates. In parallel, using a microarray approach, we observed differentially expressed (DE) genes across time, which were enriched for numerous functions, including cell migration, vascular remodeling, morphogenesis, cell communication, and inflammatory signaling. DE genes encoded several molecules that we and others previously linked to critical CTB function in vivo, suggesting that the novel DE molecules we discovered played important roles. Immunolocalization confirmed that CTBs in situ gave a signal for two of the most highly expressed genes in vitro. In summary, we characterized, at a global level, the temporal dynamics of primary human CTB gene expression in culture. These data will enable future analyses of various types of in vitro perturbations-for example, modeling disease processes and environmental exposures.

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.

Syndecan-1 Acts as an Important Regulator of CXCL1 Expression and Cellular Interaction of Human Endometrial Stromal and Trophoblast Cells

Successful implantation of the embryo into the human receptive endometrium is substantial for the establishment of a healthy pregnancy. This study focusses on the role of Syndecan-1 at the embryo-maternal interface, the multitasking coreceptor influencing ligand concentration, release and receptor presentation, and cellular morphology. CXC motif ligand 1, being involved in chemotaxis and angiogenesis during implantation, is of special interest as a ligand of Syndecan-1. Human endometrial stromal cells with and without Syndecan-1 knock-down were decidualized and treated with specific inhibitors to evaluate signaling pathways regulating CXC ligand 1 expression. Western blot analyses of MAPK and Wnt members were performed, followed by analysis of spheroid interactions between human endometrial cells and extravillous trophoblast cells. By mimicking embryo contact using IL-1β, we showed less ERK and c-Jun activation by depletion of Syndecan-1 and less Frizzled 4 production as part of the canonical Wnt pathway. Additionally, more beta-catenin was phosphorylated and therefore degraded after depletion of Syndecan-1. Secretion of CXC motif ligand 1 depends on MEK-1 with respect to Syndecan-1. Regarding the interaction of endometrial and trophoblast cells, the spheroid center-to-center distances were smaller after depletion of Syndecan-1. Therefore, Syndecan-1 seems to affect signaling processes relevant to signaling and intercellular interaction at the trophoblast-decidual interface.