The involvement of eukaryotic translation initiation factor 4E in extravillous trophoblast cell function

Three's a crowd - why did three N-terminal methyltransferases evolve for one job?

N-terminal methylation of the α-amine group (Nα-methylation) is a post-translational modification (PTM) that was discovered over 40 years ago. Although it is not the most abundant of the Nα-PTMs, there are more than 300 predicted substrates of the three known mammalian Nα-methyltransferases, METTL11A and METTL11B (also known as NTMT1 and NTMT2, respectively) and METTL13. Of these ∼300 targets, the bulk are acted upon by METTL11A. Only one substrate is known to be Nα-methylated by METTL13, and METTL11B has no proven in vivo targets or predicted targets that are not also methylated by METTL11A. Given that METTL11A could clearly handle the entire substrate burden of Nα-methylation, it is unclear why three distinct Nα-methyltransferases have evolved. However, recent evidence suggests that many methyltransferases perform important biological functions outside of their catalytic activity, and the Nα-methyltransferases might be part of this emerging group. Here, we describe the distinct expression, localization and physiological roles of each Nα-methyltransferase, and compare these characteristics to other methyltransferases with non-catalytic functions, as well as to methyltransferases with both catalytic and non-catalytic functions, to give a better understanding of the global roles of these proteins. Based on these comparisons, we hypothesize that these three enzymes do not just have one common function but are actually performing three unique jobs in the cell.

Long non-coding RNA MALAT1 regulates trophoblast functions through VEGF/VEGFR1 signaling pathway

Preeclampsia, as one of the most serious pregnancy-specific diseases, manifested by high blood pressure and companied by proteinuria in pregnancy women after 20 gestational weeks. Although the underlying mechanism has been studied for decades, no unambiguous interpretation of this phenomenon was well recognized. Recent researches focused on long non-coding RNAs (lncRNAs) as key regulators of cancer cell proliferation, invasion, migration and angiogenesis. Tumor development and placenta implantation share several common biological behaviors. The expression of lncRNA MALAT1 was downregulated in the placenta of patients with severe preeclampsia. MALAT1 smart silencer significantly inhibited HTR-8/SVneo trophoblast cell proliferation, invasion, migration and tube formation in vitro. Moreover, MALAT1 inhibited the expression of angiogenic factors in umbilical vein endothelial cells co-cultured with trophoblasts. These results indicated that MALAT1 was involved in the pathogenesis of preeclampsia and might be a candidate biomarker as well as a therapeutic target for preeclampsia.

Down-regulated long non-coding RNA PVT1 contributes to gestational diabetes mellitus and preeclampsia via regulation of human trophoblast cells

OBJECTIVE

We aimed to explore the expression level and biological function of lncRNA PVT1 in human trophoblast cells.

METHODS

The expression levels of PVT1 in cancer cell lines, HTR8/SVneo cell, HUVEC cell, the maternal placenta of GDM patients, PE patients and normal pregnancy were detected by qRT-PCR. The cell culture, cell transfection, CCK-8 assay, flow cytometry, wound scratch assay and transwell were carried out to determine the effects of silencing and overexpression of PVT1 on the HTR8/SVneo trophoblast cell line. Nuclear and chromatin RNA fraction assay, RNA-sequencing, western blot and qRT-PCR were conducted to preliminarily explore possible mechanisms.

RESULTS

The relative PVT1 expression level in HTR-8/Svneo cells was higher compared to other cancer cells and HUVEC, and was lower in the GDM and PE placentas than in the normal placentas. The results showed that PVT1 knockdown notably inhibited the proliferation, migration and invasiveness abilities of trophoblast cells, and significantly promoted the apoptosis. Furthermore, overexpression of PVT1 showed the opposite results. We identified 105 differentially expressed genes after PVT1 knockdown, 23 were up-regulated and 82 were down-regulated. GO enrichment analysis and pathway enrichment analysis showed that the DEGs were closely related to the functional changes of trophoblast cells. Because of the enrichment of 7 DEGs and less Q value, PI3K/AKT pathway was prominent and attracted our attention. More importantly, we confirmed that knockdown of PVT1 obviously decreased AKT phosphorylation and decreased the expression of DEGs (GDPD3, ITGAV and ITGB8) while overexpression of PVT1 promoted the AKT phosphorylation and increased the expression of DEGs (GDPD3, ITGAV and ITGB8). PVT1 was primarily distributed in the nuclear compartment and also distributed in the cytoplasmic of HTR-8/Svneo cells.

CONCLUSIONS

This study provided the evidence that PVT1 played a vital role in trophoblast cells, and it is important for maintaining the normal physiological function of trophoblast cells. The PVT1 expression was lower in the GDM and PE placentas than the normal placentas, which might disrupt the function of trophoblast cells through PI3K/AKT pathway.

Stage-specific feed intake restriction differentially regulates placental traits and proteome of goats

A total of twenty-four healthy twin-bearing Liuyang black goats were allocated to two trials. In Trial 1, twelve goats received either the control diet (CG, n 6, 100 % feed) or restricted diet (RG, n 6, 60 % feed of CG) from gestation days 26 to 65 after synchronisation. In Trial 2, the remaining goats were randomly and equally divided into two treatments: CG and RG from days 95 to 125 of gestation. Placental traits, fetal weight, serum parameters, nitric oxide (NO), angiogenesis gene expression and cotyledon proteome were measured at the end of each trial. In early pregnancy, the total and relative weights of placenta, uterine caruncle and cotyledon, as well as fetus, were increased (P<0·05) in RG. The NO content in maternal serum was also increased (P<0·05) in RG. In all, fifty differentially expressed proteins were identified in cotyledon. The up-regulated proteins are related to proliferation and fission of trophoblast cell and the placenta angiogenesis. During the late pregnancy trial, placental weight was increased (P<0·05) in RG, but weight of the fetus was decreased (P<0·05). The capillary density in the cotyledon was also decreased (P<0·01). A total of fifty-eight proteins were differentially expressed in cotyledon. The up-regulated proteins in RG are related to placenta formation, blood flow regulation and embryonic development. These results indicated that feed intake restriction during gestation influenced the placental and fetal development in a stage-dependent manner. These findings have important implications for developing novel nutrient management strategies in goat production.

The long noncoding RNA uc.294 is upregulated in early-onset pre-eclampsia and inhibits proliferation, invasion of trophoblast cells (HTR-8/SVneo)

Recently, a large number of long noncoding RNAs (lncRNAs) have been reported in human diseases that are evolutionarily conserved and are likely to play a role in many biological events including pre-eclampsia. In our previous research, we selected thousands of lncRNAs for their relationship with early-onset pre-eclampsia. Among these lncRNAs, a lncRNA named uc.294 attracted our attention, was once reported to specifically be expressed at a high level in the early-onset of pre-eclampsia. This study aims to investigate the function of uc.294 in early-onset pre-eclampsia and the possible mechanism. The uc.294 expression level in early-onset pre-eclampsia or in normal placenta tissues was evaluated by quantitative real-time polymerase chain reaction. To detect the proliferation, invasion, and apoptosis capacity of the trophoblast cells, we performed the Cell Counting Kit-8 assay, transwell assay, and flow cytometry, respectively. Here we report, for the first time, that uc.294 inhibits proliferation, invasion, and promotes apoptosis of trophoblast cells HTR-8/SVneo by working in key aspects of biological behaviors. However, how uc.294 acts to regulate gene functions in early-onset pre-eclampsia needs further exploration.

Promotion of trophoblast invasion by lncRNA MVIH through inducing Jun-B

Preeclampsia (PE), a pregnancy‐specific disorder, is associated with impaired uterine spiral artery remodelling, which is related to the dysfunction of trophoblast cells. Lately, mounting evidence has indicated that aberrant expression of long non‐coding RNAs (lncRNAs) is associated with various human diseases. The lncRNA MVIH transcript has been shown to decrease the severity of several diseases. However, the biological function of MVIH, which is down‐regulated in placental tissues in PE, has not yet been clarified. Here, we report that MVIH may act as a vital factor in the pathogenesis of PE. In this study, functional analysis revealed that the silencing of MVIH expression via transfection with small interfering RNA (siRNAs) inhibited cell growth, migration, invasion, and angiogenesis in various trophoblast cell lines, and stimulation with MVIH could promote these functions. Mass spectrometry analysis revealed that MVIH could modulate Jun‐B protein expression, which has been reported to potentially regulate cell growth and angiogenesis. Further cotransfection assays were performed, revealing that MVIH and Jun‐B have a synergistic effect on the regulation of angiogenesis and cell proliferation. Taking these findings together, MVIH could be associated with PE and may be a candidate biomarker for its diagnosis and treatment.

Notch2 and Notch3 suppress the proliferation and mediate invasion of trophoblast cell lines

Notch signaling pathways play important roles in cell fate and many diseases, including preeclampsia, the dysregulation of which may be the main cause of maternal mortality. This study aimed to investigate the roles of Notch2 and Notch3 in proliferation and invasion in trophoblast cell lines (BeWo and JAR). Small hairpin RNAs targeting Notch2/Notch3 and Notch2/Notch3-overexpression vectors were designed, constructed and transfected into BeWo and JAR cells. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were then used to detect Notch2 and Notch3 mRNA and protein levels, and confirm the efficiency of silence and overexpression. Flow cytometry assays were conducted to evaluate the cell cycle of the two cell lines, and transwell assays were used to detect migration and invasion. Western blot analysis was also performed to show the alteration of the cell lines' physiological activities at protein level.When Notch2 was downregulated in BeWo cells, proliferation was dramatically promoted, while migration and invasion were significantly inhibited. When Notch2 was upregulated in JAR cells, proliferation was inhibited, but migration and invasion were promoted. After overexpression of Notch3 in BeWo cells, proliferation was downregulated, but migration and invasion were both upregulated. By contrast, the silencing of Notch3 expression in JAR cells significantly enhanced proliferation, but suppressed migration and invasion. These data indicated that Notch2 and Notch3 mediate the invasion and migration of BeWo and JAR cells, and may play a potential role in early onset severe preeclampsia.

Long Non-Coding RNA Uc.187 Is Upregulated in Preeclampsia and Modulates Proliferation, Apoptosis, and Invasion of HTR-8/SVneo Trophoblast Cells

Among the preeclampsia-related long non-cording RNAs (lncRNAs) screened with a gene chip in our preliminary study, uc.187 attracted our attention because of its high conservation across different species and significant positive correlation with preeclampsia (PE). The literature and bioinformatics analysis suggested that lncRNA uc.187 might be associated with cell growth, invasion, and apoptosis. The expression of uc.187 in severe preeclamptic placentas (n = 31) and normal placentas (n = 18) was evaluated by real-time reverse transcription polymerase chain reaction (qRT-PCR). We constructed a silencing lentivirus vector (uc.187 siRNA) to explore the biological function of uc.187 in the development and progression of HTR-8/SVneo trophoblast cells in vitro. Furthermore, we utilized CCK8 analysis, a transwell invasion assay, and flow cytometry to determine the role of uc.187 in the proliferation, invasion, and apoptosis of HTR-8/SVneo trophoblast cells. The proteins related to proliferation (PCNA, Ki67), invasion (MMP-2/-9 and TIMP-1), and apoptosis (caspase-3, Bcl-2) were evaluated with a Western blot assay. The results showed that there was an obvious upregulation of uc.187 expression in preeclamptic placental tissues. In addition, uc.187 silencing enhanced cell proliferation and invasion and reduced the cellular apoptotic response. Taken together, our findings suggest for the first time that abnormal expression of lncRNA uc.187 may lead to the aberrant biological behavior of HTR-8/SVneo cells. Therefore, we propose uc.187 as a novel lncRNA molecule that might contribute to the development of PE and might represent a potential diagnostic and therapeutic target for this disease. J. Cell. Biochem. 118: 1462-1470, 2017. © 2016 Wiley Periodicals, Inc.

The Lnc RNA SPRY4-IT1 Modulates Trophoblast Cell Invasion and Migration by Affecting the Epithelial-Mesenchymal Transition

Preeclampsia is a common, pregnancy-specific disease and a major contributor to maternal and foetal morbidity and mortality. Some placental abnormalities, including deficient implantation, abnormal trophoblast cell function, and improper placental vascular development, are believed to lead to preeclampsia. The long noncoding RNA SPRY4-IT1 is more highly expressed in preeclamptic human placentas than in normal placentas. We assessed the role of epithelial-mesenchymal transition (EMT)-associated invasion and migration in HTR-8/SVneo trophoblast cells. Overexpression of SPRY4-IT1 suppressed trophoblast cell migration and invasion, whereas reduced expression of SPRY4-IT1 prevented the EMT process. Mechanistically, an RNA immunoprecipitation experiment showed that SPRY4-IT1 bound directly to HuR and mediated the β-catenin expression associated with EMT in HTR-8/SVneo cells. Moreover, the expression levels of genes in the WNT family, such as WNT3 and WNT5B, were changed after transfection of HTR-8/SVneo with SPRY4-IT1. Together, our results highlight the roles of SPRY4-IT1 in causing trophoblast cell dysfunction by acting through the Wnt/β-catenin pathway, and consequently in impairing spiral artery remodelling. These results suggest a new potential therapeutic target for intervention against preeclampsia.

Role of SOCS3 in the Jak/stat3 pathway in the human placenta: different mechanisms for preterm and term labor

INTRODUCTION

To identify changes in interleukin (IL)-6 levels and its pathway (Jak/stat3) in the human placenta during preterm and term labor, placental tissues were collected from primiparous women who underwent vaginal deliveries or cesarean sections in our hospital. The women were divided into three groups: preterm labor (n = 15), term labor (n = 15), and term not in labor (n = 15).

MATERIAL AND METHODS

IL-6 levels were detected by ELISA in placental supernatant, and p-STAT3 and SOCS3 protein was detected by Western blot. TUNEL was used to detect apoptosis in trophoblasts. HTR-8/SVneo cells were cultured after stimulation with IL-6, and we measured p-STAT3, SOCS3, and the rate of apoptosis.

RESULTS

Expression of p-STAT3 and SOCS3 in the placenta and trophoblast cells showed that IL-6 levels were highest in the preterm labor group and lowest in the term not in labor group. The highest expression of placental SOCS3 protein was observed in the preterm labor group. More apoptotic cells were found in the preterm labor group than in the other two groups by TUNEL. SOCS3 and p-STAT3 expression was significantly upregulated after stimulation by IL-6 in trophoblast cells in a dose-dependent manner. However, p-STAT3 was significantly decreased after 50 ng/mL and 100 ng/mL IL-6 for 72 h. A significant increase of apoptosis was observed with treatment of 50 ng/mL IL-6 in HTR-8/SVneo cells.

CONCLUSIONS

The role of the SOCS3 protein in the Jak/stat3 pathway is to mediate different mechanisms for preterm and term labor processes in the placenta.

Decorin-Mediated Inhibition of Human Trophoblast Cells Proliferation, Migration, and Invasion and Promotion of Apoptosis In Vitro

Preeclampsia (PE) is a unique complication of pregnancy, the pathogenesis of which has been generally accepted to be associated with the dysfunctions of extravillous trophoblast (EVT) including proliferation, apoptosis, and migration and invasion. Decorin (DCN) has been proved to be a decidua-derived TGF-binding proteoglycan, which negatively regulates proliferation, migration, and invasiveness of human extravillous trophoblast cells. In this study, we identified a higher expression level of decorin in severe PE placentas by both real-time reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). And an inhibitory effect of decorin on proliferation, migration, and invasion and an enhanced effect on apoptosis in trophoblast cells HTR-8/SVneo and JEG-3 were validated in vitro. Also the modulations of decorin on trophoblast cells' metastasis and invasion functions were detected through regulating the matrix metalloproteinases (MMP2 and MMP9). Thus, we suggested that the contribution of decorin to the modulation of trophoblast cells might have implications for the pathogenesis of preeclampsia.

Dynamic proteomic profiles of in vivo- and in vitro-produced mouse postimplantation extraembryonic tissues and placentas

As the interface between the mother and the developing fetus, the placenta is believed to play an important role in assisted reproductive technology (ART)-induced aberrant intrauterine and postnatal development. However, the mechanisms underlying aberrant placentation remain unclear, especially during extraembryonic tissue development and early stages of placental formation. Using a mouse model, this investigation provides the first comparative proteomic analysis of in vivo (IVO) and in vitro-produced (IVP) extraembryonic tissues and placentas after IVO fertilization and development, or in vitro fertilization and culture, respectively. We identified 165 and 178 differentially expressed proteins (DEPs) between IVO and IVP extraembryonic tissues and placentas on Embryonic Day 7.5 (E7.5) and E10.5, respectively. Many DEPs were functionally associated with genetic information processing, such as impaired de novo DNA methylation, as well as posttranscriptional, translational and posttranslational dysregulation. These novel findings were further confirmed by global hypomethylation, and a lower level of correlation was found between the transcriptome and proteome in the IVP groups. In addition, numerous DEPs were involved in energy and amino acid metabolism, cytoskeleton organization and transport, and vasculogenesis and angiogenesis. These disturbed processes and pathways are likely to be associated with embryonic intrauterine growth restriction, an enlarged placenta, and impaired labyrinth morphogenesis. This study provides a direct and comprehensive reference for the further exploration of the placental mechanisms that underlie ART-induced developmental aberrations.

MiR-101 regulates apoptosis of trophoblast HTR-8/SVneo cells by targeting endoplasmic reticulum (ER) protein 44 during preeclampsia

To investigate a possible association between miR-101 and apoptosis of human trophoblast cells mediated by endoplasmic reticulum protein 44 (ERp44) in preeclampsia (PE), we explored the expression of miR-101 in PE placentas (n=30) compared with normotensive pregnant placentas (n=30) and the correlation between miR-101 and ERp44 was also analyzed. Furthermore, both the apoptotic rate of trophoblast cells and the ER stress-induced apoptotic proteins were assayed when the HTR-8/SVneo cells were treated with miR-101 mimics or inhibitors in vitro. We found a lower expression of miR-101 and an inverse correlation between miR-101 and ERp44 protein in PE placentas. Upregulation of miR-101 expression could inhibit trophoblast HTR-8/SVneo cell apoptosis and repress ER stress-induced apoptotic proteins by targeting ERp44 in vitro, whereas inhibition of miR-101 could induce HTR-8/SVneo cell apoptosis. Our findings indicated that overexpression of miR-101 could downregulate ERp44 and suppress apoptosis in trophoblast cells during PE. Therefore, loss of miR-101 expression could contribute to ER stress-induced trophoblast cell apoptosis by targeting ERp44.

The effect of heat shock protein 27 on extravillous trophoblast differentiation and on eukaryotic translation initiation factor 4E expression

Heat shock protein (HSP27) is expressed in human placentae. Previously, we showed that HSP27 is expressed in the villous cell column of first trimester placental explants and in extravillous trophoblast (EVT) cells. EVT differentiation is accompanied by increased motility, matrix metalloproteinase (MMP) activity, decreased proliferation and expression of specific markers such as HLAG and CD9. HSP27 regulates cell apoptosis, migration, protein stability and the availability of eukaryotic translation initiation factors, such as eukaryotic translation initiation factor 4E (eIF4E). eIF4E supports trophoblast cell proliferation and survival. We wanted to explore the effect of HSP27 silencing on trophoblast cell phenotype, EVT markers and eIF4E expression and regulators [4E-binding protein (4E-BP1) and MAP kinase-interacting kinase (MNK1)]. This study evaluated the effect of HSP27 siRNA on placental explant and HTR-8/SVneo migration, MMP activity/mRNA, cell death, cell cycle, HLAG/CD9 levels, and eIF4E and its regulators' total and phosphorylated levels. Furthermore, we evaluated HSP27 levels in placentae exposed to ribavirin, which triggers EVT differentiation. We found that HSP27 silencing increased cell death in HTR-8/SVneo and placental explants. Furthermore, it reduced HTR-8/SVneo migration and EVT outgrowth from the explants (P < 0.05), MMP2 activity and expression of EVT markers HLAG and CD9 (in placental explants and HTR-8/SVneo, respectively, P < 0.05). Induction of EVT differentiation by ribavirin elevated HSP27 levels. Finally, HSP27 silencing in both HTR-8/SVneo and placental explants reduced eIF4E levels (33 and 28%, respectively, P < 0.05) and the levels of its regulators 4E-BP1 and MNK1 (37 and 32%, respectively, done on HTR-8/SVneo only), but not their phosphorylated forms. Altogether, our results suggest that HSP27 contributes to EVT cell differentiation.

Upregulation of long noncoding RNA SPRY4-IT1 modulates proliferation, migration, apoptosis, and network formation in trophoblast cells HTR-8SV/neo

SPRY4-IT1 has been reported to have extremely high expression in normal placenta tissues. It is a Long noncoding RNA (lncRNA), which is associated with cell growth, migration, invasion, and apoptosis in melanoma. A 2.8-fold increase of SPRY4-IT1 expression was validated by Real-time reverse transcription-polymerase chain reaction (qRT-PCR) in severe preeclamptic placenta as compared with that of the normal ones (n=25) in this study. Furthermore, the role of SPRY4-IT1 in proliferation, migration, apoptosis, and network formation ability of trophoblast cells HTR-8/SVneo was assessed. Suppression of SPRY4-IT1 using siRNA treatment and its overexpression using plasmid targeting SPRY4-IT1 were performed in order to explore the biological function of SPRY4-IT1 in the development and progression of trophoblast cells HTR-8/SVneo, in vitro. The results showed that SPRY4-IT1 knockdown enhanced the cell migration and proliferation, and reduced the response of cells to apoptosis. However, exogenous SPRY4-IT1 overexpression significantly decreased the cell migration and proliferation, while increased cell apoptosis. Our study showed for the first time that aberrant expression of lncRNA SPRY4-IT1 might contribute to the abnormal condition of trophoblast cells HTR-8/SVneo. Therefore, we proposed SPRY4-IT1 as a novel lncRNA molecule, which might be associated with the pathogenesis of preeclampsia and might provide a new target for its early diagnosis and treatment.