p45 NF-E2 regulates syncytiotrophoblast differentiation by post-translational GCM1 modifications in human intrauterine growth restriction

Increased EHD1 in trophoblasts causes RSM by activating TGFβ signaling†

BACKGROUND

Recurrent spontaneous miscarriage is one of the complications during pregnancy. However, the pathogenesis of recurrent spontaneous miscarriage is far from fully elucidated.

OBJECTIVE

Since the endocytic pathway is crucial for cellular homeostasis, our study aimed to explore the roles of endocytic recycling, especially EH domain containing 1, a member of the endocytic recycling compartment, in recurrent spontaneous miscarriage.

STUDY DESIGN

We first investigated the expression of the endocytic pathway member EH domain containing 1 in villi from the normal and recurrent spontaneous miscarriage groups. Then, we performed ribonucleic acid sequencing and experiments in villi, HTR8 cells and BeWo cells to determine the mechanisms by which EH domain containing 1-induced recurrent spontaneous miscarriage. Finally, placenta-specific EH domain containing 1-overexpressing mice were generated to investigate the recurrent spontaneous miscarriage phenotype in vivo.

RESULTS

EH domain containing 1 was expressed in extravillous trophoblasts and syncytiotrophoblast in the villi. Compared with the control group, recurrent spontaneous miscarriage patients expressed higher EH domain containing 1. A high level of EH domain containing 1 decreased proliferation, promoted apoptosis, and reduced the migration and invasion of HTR8 cells by activating the TGFβ receptor 1-SMAD2/3 signaling pathway. The TGFβ receptor 1 antagonist LY3200882 partially reversed the EH domain containing 1 overexpression-induced changes in the cell phenotype. Besides, a high level of EH domain containing 1 also induced abnormal syncytialization, which disturbed maternal-fetal material exchanges. In a mouse model, placenta-specific overexpression of EH domain containing 1 led to the failure of spiral artery remodeling, excessive syncytialization, and miscarriage.

CONCLUSIONS

Increased expression of EH domain containing 1 impaired the invasion of extravillous trophoblasts mediated by the TGFβ receptor 1-SMAD2/3 signaling pathway and induced abnormal syncytialization of syncytiotrophoblast, which is at least partially responsible for recurrent spontaneous miscarriage.

Spatial multiomic landscape of the human placenta at molecular resolution

Successful pregnancy relies directly on the placenta's complex, dynamic, gene-regulatory networks. Disruption of this vast collection of intercellular and intracellular programs leads to pregnancy complications and developmental defects. In the present study, we generated a comprehensive, spatially resolved, multimodal cell census elucidating the molecular architecture of the first trimester human placenta. We utilized paired single-nucleus (sn)ATAC (assay for transposase accessible chromatin) sequencing and RNA sequencing (RNA-seq), spatial snATAC-seq and RNA-seq, and in situ sequencing and hybridization mapping of transcriptomes at molecular resolution to spatially reconstruct the joint epigenomic and transcriptomic regulatory landscape. Paired analyses unraveled intricate tumor-like gene expression and transcription factor motif programs potentially sustaining the placenta in a hostile uterine environment; further investigation of gene-linked cis-regulatory elements revealed heightened regulatory complexity that may govern trophoblast differentiation and placental disease risk. Complementary spatial mapping techniques decoded these programs within the placental villous core and extravillous trophoblast cell column architecture while simultaneously revealing niche-establishing transcriptional elements and cell-cell communication. Finally, we computationally imputed genome-wide, multiomic single-cell profiles and spatially characterized the placental chromatin accessibility landscape. This spatially resolved, single-cell multiomic framework of the first trimester human placenta serves as a blueprint for future studies on early placental development and pregnancy.

Insight into the post-translational modifications in pregnancy and related complications

Successful pregnancy is dependent on a number of essential events, including embryo implantation, decidualization and placentation. Failure of the above process may lead to pregnancy-related complications, including preeclampsia (PE), gestational diabetes mellitus (GDM), preterm birth, fetal growth restriction (FGR), etc., may affect 15% of pregnancies, and lead to increased mortality and morbidity of pregnant women and perinatal infants, as well as the occurrence of short-term and long-term diseases. These complications have distinct etiology and pathogenesis, and the present comprehension is still lacking. Post-translational modifications (PTMs) are important events in epigenetics, altering the properties of proteins through protein hydrolysis or the addition of modification groups to one or more amino acids, with different modification states regulating subcellular localization, protein degradation, protein-protein interaction, signal transduction and gene transcription. In this review, we focus on the impact of various PTMs on the progress of embryo and placenta development and pregnancy-related complications, which will provide important experimental bases for exploring new insights into the physiology of pregnancy and pathogenesis associated with pregnancy complications.

Homeobox genes in the human placenta: Twists and turns on the path to find novel targets

Fetal growth restriction (FGR) is a clinically important human pregnancy disorder that is thought to originate early in pregnancy and while its aetiology is not well understood, the disorder is associated with placental insufficiency. Currently treatment for FGR is limited by increased surveillance using ultrasound monitoring and premature delivery, or corticosteroid medication in the third trimester to prolong pregnancy. There is a pressing need for novel strategies to detect and treat FGR at its early stage. Homeobox genes are well established as master regulators of early embryonic development and increasing evidence suggests they are also important in regulating early placental development. Most important is that specific homeobox genes are abnormally expressed in human FGR. This review focusses on identifying the molecular pathways controlled by homeobox genes in the normal and FGR-affected placenta. This information will begin to address the knowledge gap in the molecular aetiology of FGR and lay the foundation for identifying potential diagnostic and therapeutic targets.

miR-181d-5p, which is upregulated in fetal growth restriction placentas, inhibits trophoblast fusion via CREBRF

PURPOSE

Fetal growth restriction (FGR) is a common complication characterized by impaired placental function and unfavorable pregnancy outcomes. This study aims to elucidate the expression pattern of miR-181d-5p in FGR placentas and explore its effects on trophoblast fusion.

METHODS

The expression pattern of miR-181d-5p in human FGR placentas were evaluated using qRT-PCR. Western blot, qRT-PCR, and Immunofluorescence analysis were performed in a Forskolin (FSK)-induced BeWo cell fusion model following the transfection of miR-181d-5p mimic or inhibitor. Potential target genes for miR-181d-5p were identified by screening miRNA databases. The interaction between miR-181d-5p and Luman/CREB3 Recruitment Factor (CREBRF) was determined through a luciferase assay. Moreover, the effect of CREBRF on BeWo cell fusion was examined under hypoxic conditions.

RESULTS

Aberrant up-regulation of miR-181d-5p and altered expression of trophoblast fusion makers, including glial cell missing 1 (GCM1), Syncytin1 (Syn1), and E-cadherin (ECAD), were found in human FGR placentas. A down-regulation of miR-181d-5p expression was observed in the FSK-induced BeWo cell fusion model. Transfection of the miR-181d-5p mimic resulted in the inhibition of BeWo cell fusion, characterized by a down-regulation of GCM1 and Syn1, accompanied by an up-regulation of ECAD. Conversely, the miR-181d-5p inhibitor promoted BeWo cell fusion. Furthermore, miR-181d-5p exhibited negative regulation of CREBRF, which was significantly down-regulated in the hypoxia-induced BeWo cell model. The overexpression of CREBRF was effectively ameliorated the impaired BeWo cell fusion induced by hypoxia.

CONCLUSIONS

Our study demonstrated that miR-181d-5p, which is elevated in FGR placenta, inhibited the BeWo cell fusion through negatively regulating the expression of CREBRF.

Regulators involved in trophoblast syncytialization in the placenta of intrauterine growth restriction

Placental dysfunction refers to the insufficiency of placental perfusion and chronic hypoxia during early pregnancy, which impairs placental function and causes inadequate supply of oxygen and nutrients to the fetus, affecting fetal development and health. Fetal intrauterine growth restriction, one of the most common outcomes of pregnancy-induced hypertensions, can be caused by placental dysfunction, resulting from deficient trophoblast syncytialization, inadequate trophoblast invasion and impaired vascular remodeling. During placental development, cytotrophoblasts fuse to form a multinucleated syncytia barrier, which supplies oxygen and nutrients to meet the metabolic demands for fetal growth. A reduction in the cell fusion index and the number of nuclei in the syncytiotrophoblast are found in the placentas of pregnancies complicated by IUGR, suggesting that the occurrence of IUGR may be related to inadequate trophoblast syncytialization. During the multiple processes of trophoblasts syncytialization, specific proteins and several signaling pathways are involved in coordinating these events and regulating placental function. In addition, epigenetic modifications, cell metabolism, senescence, and autophagy are also involved. Study findings have indicated several abnormally expressed syncytialization-related proteins and signaling pathways in the placentas of pregnancies complicated by IUGR, suggesting that these elements may play a crucial role in the occurrence of IUGR. In this review, we discuss the regulators of trophoblast syncytialization and their abnormal expression in the placentas of pregnancies complicated by IUGR.

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.

Procoagulant Extracellular Vesicles Alter Trophoblast Differentiation in Mice by a Thrombo-Inflammatory Mechanism

Procoagulant extracellular vesicles (EV) and platelet activation have been associated with gestational vascular complications. EV-induced platelet-mediated placental inflammasome activation has been shown to cause preeclampsia-like symptoms in mice. However, the effect of EV-mediated placental thrombo-inflammation on trophoblast differentiation remains unknown. Here, we identify that the EV-induced thrombo-inflammatory pathway modulates trophoblast morphology and differentiation. EVs and platelets reduce syncytiotrophoblast differentiation while increasing giant trophoblast and spongiotrophoblast including the glycogen-rich cells. These effects are platelet-dependent and mediated by the NLRP3 inflammasome. In humans, inflammasome activation was negatively correlated with trophoblast differentiation marker GCM1 and positively correlated with blood pressure. These data identify a crucial role of EV-induced placental thrombo-inflammation on altering trophoblast differentiation and suggest platelet activation or inflammasome activation as a therapeutic target in order to achieve successful placentation.

Association of Elevated Maternal Serum Total Bile Acids With Low Birth Weight and Intrauterine Fetal Growth Restriction

IMPORTANCE

Bile acids play essential roles in metabolic modulation. Excessive serum total bile acid (sTBA) levels during pregnancy are associated with adverse perinatal outcomes; however, their association with the risk of intrauterine growth restriction (IUGR) remains unclear.

OBJECTIVE

To investigate the association between maternal sTBA concentration during pregnancy and the risk of IUGR.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included pregnant individuals who delivered live singleton neonates and had regular antenatal examination records available at a hospital-based center in Shanghai, China, from 2014 to 2018. Data were analyzed from July to November 2020.

EXPOSURES

Maternal sTBA concentration during pregnancy.

MAIN OUTCOMES AND MEASURES

Fetal birth weight and probability of low birth weight (LBW) and IUGR.

RESULTS

This study included 68 245 singleton pregnancies with live births for analysis. The mean (SD) age of the pregnant individuals was 30.5 (3.8) years, 67 168 patients (98.4%) were Han, and 50 155 (73.5%) were nulliparous. Nonlinear regression models suggested that there was an inverted J-shaped association between maternal sTBA level during pregnancy and fetal birth weight, with a steep decrease in birth weight at high sTBA levels (estimated mean [SE] birth weight for sTBA of 40.8 ug/mL, 2879 [39.9] g) and greater birth weights at lower sTBA levels (estimated mean [SE] birth weight for sTBA 0.4 μg/mL, 3290 [3.9] g; and for 4.1 μg/mL, 3334 [1.6] g). Lower birth weight and a higher incidence of IUGR were observed in patients with gestational hypercholanemia (sTBA ≥4.08 μg/mL) compared with those without gestational hypercholanemia (birth weight: estimated adjusted mean [SE], 3309 [3.32] vs 3338 [0.80] g; P = .005; incidence of IUGR: 62 of 4467 [1.4%] vs 312 of 63 778 [0.5%]; P < .001). Moreover, compared with patients with sTBA concentrations of less than 4.08 μg/mL, those with gestational hypercholanemia had an increased risk of LBW (adjusted odds ratio [aOR], 1.29; 95% CI, 1.09-1.53) and IUGR (aOR, 2.18; 95% CI, 1.62-2.91). In addition, there was an additive interaction between hypertensive disorders in pregnancy (HDP) and hypercholanemia on LBW and IUGR risk. The highest risks of LBW and IUGR were found in pregnant individuals with both HDP and hypercholanemia compared with those with normotensive pregnancies with sTBA concentrations less than 4.08 μg/mL (LBW: aOR, 9.13; 95% CI, 6.88-12.12; IUGR: aOR, 19.14; 95% CI, 12.09-30.28).

CONCLUSIONS AND RELEVANCE

This study found that gestational hypercholanemia was associated with an increased risk of LBW and IUGR, especially in pregnant individuals with HDP. Therefore, it would be meaningful to monitor sTBA concentration during the follow-up of pregnancies with potential IUGR.

Placental thromboinflammation impairs embryonic survival by reducing placental thrombomodulin expression

Excess platelet activation by extracellular vesicles (EVs) results in trophoblast inflammasome activation, interleukin 1β (IL-1β) activation, preeclampsia (PE), and partial embryonic lethality. Embryonic thrombomodulin (TM) deficiency, which causes embryonic lethality hallmarked by impaired trophoblast proliferation, has been linked with maternal platelet activation. We hypothesized that placental TM loss, platelet activation, and embryonic lethality are mechanistically linked to trophoblast inflammasome activation. Here, we uncover unidirectional interaction of placental inflammasome activation and reduced placental TM expression: although inflammasome inhibition did not rescue TM-null embryos from lethality, the inflammasome-dependent cytokine IL-1β reduced trophoblast TM expression and impaired pregnancy outcome. EVs, known to induce placental inflammasome activation, reduced trophoblast TM expression and proliferation. Trophoblast TM expression correlated negatively with IL-1β expression and positively with platelet numbers and trophoblast proliferation in human PE placentae, implying translational relevance. Soluble TM treatment or placental TM restoration ameliorated the EV-induced PE-like phenotype in mice, preventing placental thromboinflammation and embryonic death. The lethality of TM-null embryos is not a consequence of placental NLRP3 inflammasome activation. Conversely, EV-induced placental inflammasome activation reduces placental TM expression, promoting placental and embryonic demise. These data identify a new function of placental TM in PE and suggest that soluble TM limits thromboinflammatory pregnancy complications.

Phosphorylation of Yes-associated protein impairs trophoblast invasion and migration: implications for the pathogenesis of fetal growth restriction†

Fetal growth restriction (FGR) is a condition in which a newborn fails to achieve his or her prospective hereditary growth potential. This condition is associated with high newborn mortality, second only to that associated with premature birth. FGR is associated with maternal, fetal, and placental abnormalities. Although the placenta is considered to be an important organ for supplying nutrition for fetal growth, research on FGR is limited, and treatment through the placenta remains challenging, as neither proper uterine intervention nor its pathogenesis have been fully elucidated. Yes-associated protein (YAP), as the effector of the Hippo pathway, is widely known to regulate organ growth and cancer development. Therefore, the correlation of the placenta and YAP was investigated to elucidate the pathogenic mechanism of FGR. Placental samples from humans and mice were collected for histological and biomechanical analysis. After investigating the location and role of YAP in the placenta by immunohistochemistry, we observed that YAP and cytokeratin 7 have corresponding locations in human and mouse placentas. Moreover, phosphorylated YAP (p-YAP) was upregulated in FGR and gradually increased as gestational age increased during pregnancy. Cell function experiments and mRNA-Seq demonstrated impaired YAP activity mediated by extracellular signal-regulated kinase inhibition. Established FGR-like mice also recapitulated a number of the features of human FGR. The results of this study may help to elucidate the association of FGR development with YAP and provide an intrauterine target that may be helpful in alleviating placental dysfunction.

Platelet-derived factors impair placental chorionic gonadotropin beta-subunit synthesis

Abstract

During histiotrophic nutrition of the embryo, maternal platelets may be the first circulating maternal cells that find their way into the placental intervillous space through narrow intertrophoblastic gaps within the plugs of spiral arteries. Activation of platelets at the maternal-fetal interface can influence trophoblast behavior and has been implicated in serious pregnancy pathologies. Here, we show that platelet-derived factors impaired expression and secretion of the human chorionic gonadotropin beta-subunit (βhCG) in human first trimester placental explants and the trophoblast cell line BeWo. Impaired βhCG synthesis was not the consequence of hampered morphological differentiation, as assessed by analysis of differentiation-associated genes and electron microscopy. Platelet-derived factors did not affect intracellular cAMP levels and phosphorylation of CREB, but activated Smad3 and its downstream-target plasminogen activator inhibitor (PAI)-1 in forskolin-induced BeWo cell differentiation. While TGF-β type I receptor inhibitor SB431542 did not restore impaired βhCG production in response to platelet-derived factors, Smad3 inhibitor SIS3 interfered with CREB activation, suggesting an interaction of cAMP/CREB and Smad3 signaling. Sequestration of transcription co-activators CBP/p300, known to bind both CREB and Smad3, may limit βhCG production, since CBP/p300 inhibitor C646 significantly restricted its forskolin-induced upregulation. In conclusion, our study suggests that degranulation of maternal platelets at the early maternal-fetal interface can impair placental βhCG production, without substantially affecting morphological and biochemical differentiation of villous trophoblasts.

Key messages

Maternal platelets can be detected on the surface of the placental villi and in intercellular gaps of trophoblast cell columns from gestational week 5 onwards.

Platelet-derived factors impair hCG synthesis in human first trimester placenta.

Platelet-derived factors activate Smad3 in trophoblasts.

Smad3 inhibitor SIS3 interferes with forskolin-induced CREB signaling.

Sequestration of CBP/p300 by activated Smad3 may limit placental hCG production.

Electronic supplementary material

The online version of this article (10.1007/s00109-019-01866-x) contains supplementary material, which is available to authorized users.

Silencing BRIT1 Facilitates the Abilities of Invasiveness and Migration in Trophoblast Cells

Background

The improper invasion of trophoblast cells (TC) can cause various diseases. BRCT-repeat inhibitor of hTERT expression (BRIT1) is involved in the invasion of tumors. Here, we analyzed the effects of BRIT1 on the invasion of TC.

Material/Methods

The expression of BRIT1 in JEG-3, B6Tert, and HTR8/SVneo cells was evaluated by transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting. The viability, invasion, and migration of HTR8/SVneo cells were measured using cell counting kit-8 (CCK-8) and Transwell assays. The activities of pro-matrix metalloproteinase-2 (pro-MMP-2) and pro-MMP-9 were tested by gelatin zymography assay. The levels of invasion- and Wnt/β-catenin pathway-related factors were assessed by RT-qPCR and Western blotting.

Results

Levels of BRIT1 in HTR8/SVneo cells were higher than that of JEG-3 and B6Tert cells. The transfection efficiency of BRIT1 siRNA-2 was better than BRIT1 siRNA-1 in HTR8/SVneo cells. BRIT1 siRNA-2 did not change cell viability, whereas it promoted cell invasion and migration. BRIT1 siRNA-2 enhanced the activities of pro-MMP-2 and pro-MMP-9, as well MMP-2 and MMP-9 levels, and reduced tissue inhibitor of metalloproteinases-1 (TIMP-1) and TIMP-2 expression. Moreover, BRIT1 siRNA-2 significantly increased the levels of Wnt2, Wnt3, and β-catenin.

Conclusions

BRIT1 silencing accelerated the invasion and migration of TC and activated the Wnt/β-catenin pathway. Our results may provide new insights for finding new molecular targets to cure disease caused by insufficient invasion of TC.

Regulation of Placental Development and Its Impact on Fetal Growth-New Insights From Mouse Models

The placenta is the chief regulator of nutrient supply to the growing embryo during gestation. As such, adequate placental function is instrumental for developmental progression throughout intrauterine development. One of the most common complications during pregnancy is insufficient growth of the fetus, a problem termed intrauterine growth restriction (IUGR) that is most frequently rooted in a malfunctional placenta. Together with conventional gene targeting approaches, recent advances in screening mouse mutants for placental defects, combined with the ability to rapidly induce mutations in vitro and in vivo by CRISPR-Cas9 technology, has provided new insights into the contribution of the genome to normal placental development. Most importantly, these data have demonstrated that far more genes are required for normal placentation than previously appreciated. Here, we provide a summary of common types of placental defects in established mouse mutants, which will help us gain a better understanding of the genes impacting on human placentation. Based on a recent mouse mutant screen, we then provide examples on how these data can be mined to identify novel molecular hubs that may be critical for placental development. Given the close association between placental defects and abnormal cardiovascular and brain development, these functional nodes may also shed light onto the etiology of birth defects that co-occur with placental malformations. Taken together, recent insights into the regulation of mouse placental development have opened up new avenues for research that will promote the study of human pregnancy conditions, notably those based on defects in placentation that underlie the most common pregnancy pathologies such as IUGR and pre-eclampsia.

Decreased PGF may contribute to trophoblast dysfunction in fetal growth restriction

Fetal growth restriction (FGR) threatens perinatal health and is correlated with increased incidence of fetal original adult diseases. Most cases of FGR were idiopathic, which were supposed to be associated with placental abnormality. Decreased circulating placental growth factor (PGF) was recognized as an indication of placental deficiency in FGR. In this study, the epigenetic regulation of PGF in FGR placentas and the involvement of PGF in modulation of trophoblast activity were investigated. The expression level of PGF in placental tissues was determined by RT-qPCR, immunohistochemistry and ELISA. DNA methylation profile of PGF gene was analyzed by bisulfite sequencing. Trophoblastic cell lines were treated with ZM-306416, an inhibitor of PGF receptor FLT1, to observe the effect of PGF/FLT1 signaling on cell proliferation and migration. We demonstrated that PGF was downregulated in placentas from FGR pregnancies compared with normal controls. The villous expression of PGF was positively correlated with placental and fetal weight. The CpG island inside PGF promoter was hypomethylated without obvious difference in both normal and FGR placentas. However, the higher DNA methylation at another CpG island downstream exon 7 of PGF was demonstrated in FGR placentas. Additionally, we found FLT1 was expressed in trophoblast cells. Inhibition of PGF/FLT1 signaling by a selective inhibitor impaired trophoblast proliferation and migration. In conclusion, our data suggested that the PGF expression was dysregulated, and disrupted PGF/FLT1 signaling in trophoblast might contribute to placenta dysfunction in FGR. Thus, our results support the significant role of PGF in the pathogenesis of FGR.