Human Placental Trophoblast Cell Line Research Articles

Effects of valproic acid on syncytialization in human placental trophoblast cell lines

The placenta is a critical organ for fetal development and a healthy pregnancy, and has multifaceted functions (e.g., substance exchange and hormone secretion). Syncytialization of trophoblasts is important for maintaining placental functions. Epilepsy is one of the most common neurological conditions worldwide. Therefore, this study aimed to reveal the influence of antiepileptic drugs, including valproic acid (VPA), carbamazepine, lamotrigine, gabapentin, levetiracetam, topiramate, lacosamide, and clobazam, at clinically relevant concentrations on syncytialization using in vitro models of trophoblasts. To induce differentiation into syncytiotrophoblast-like cells, BeWo cells were treated with forskolin. Exposure to VPA was found to dose-dependently influence syncytialization-associated genes (ERVW-1, ERVFRD-1, GJA1, CGB, CSH, SLC1A5, and ABCC4) in differentiated BeWo cells. Herein, the biomarkers between differentiated BeWo cells and the human trophoblast stem model (TSCT) were compared. In particular, MFSD2A levels were low in BeWo cells but abundant in TSCT cells. VPA exposure affected the expression of ERVW-1, ERVFRD-1, GJA1, CSH, MFSD2A, and ABCC4 in differentiated cells (ST-TSCT). Furthermore, VPA exposure attenuated BeWo and TSCT cell fusion. Finally, the relationships between neonatal/placental parameters and the expression of syncytialization markers in human term placentas were analyzed. MFSD2A expression was positively correlated with neonatal body weight, head circumference, chest circumference, and placental weight. Our findings have important implications for better understanding the mechanisms of toxicity of antiepileptic drugs and predicting the risks to placental and fetal development.

WITHDRAWN: Circ_0014736 induces GPR4 to regulate the biological behaviors of a human placental trophoblast cell line through miR-942-5p in preeclampsia

WITHDRAWN: Circ_0014736 induces GPR4 to regulate the biological behaviors of a human placental trophoblast cell line through miR-942-5p in preeclampsia

Perfluorooctanoic acid exposure increases both proliferation and apoptosis of human placental trophoblast cells mediated by ER stress-induced ROS or UPR pathways

Perfluorooctanoate acid (PFOA) is a highly persistent and widespread chemical in the environment. PFOA serum levels in pregnant women are positively associated with an increased risk of placenta-related disorders. However, the mechanism of PFOA cytotoxicity involved in placental cells and cellular responses such as ER stress remains poorly understood. In this study, we studied the cellular toxicity of PFOA with a focus on proliferation and apoptosis in a human placental trophoblast cell line. Cell viability, number, apoptosis, stress response, activation of the involved signaling pathways were assessed. Our results showed PFOA affected cell viability, proliferation and also resulted in apoptosis. Besides, both pro-proliferation and pro-apoptosis effects were attenuated by endoplasmic reticulum (ER) stress inhibitors. Further experiments demonstrated that two different signaling pathways were activated by PFOA-induced ER stress and involved in PFOA toxicity: the reactive oxygen species (ROS)-dependent ERK signaling triggered trophoblast proliferation, while the ATF4-dependent C/EBP homologous protein (CHOP) signaling was the trigger of apoptosis. We conclude that PFOA-induced ER stress is the trigger of proliferation and apoptosis of trophoblast via ROS or UPR signaling pathway, which leads to the altered balance critical to the normal development and function of the placenta.

CTRP9 decreases high glucose‑induced trophoblast cell damage by reducing endoplasmic reticulum stress

C1q/TNF-α-related protein 9 (CTRP9) is downregulated in gestational diabetes mellitus (GDM) and may exert a protective effect against GDM, although its mechanism of action is yet to be elucidated. To investigate the specific role of CTRP9 in GDM, the human placental trophoblast cell line HTR8/SVneo was treated with high glucose (HG) to simulate the environment of GDM in vitro. The effects of CTRP9 on the HTR8/SVneo cells and endoplasmic reticulum (ER) stress were analyzed before and after CTRP9 overexpression using reverse transcription-quantitative PCR and western blotting. The results obtained demonstrated that CTRP9 alleviated ER stress in the trophoblast cell line. After treating with the ER-stress inducer tunicamycin, cell viability was investigated by performing Cell Counting Kit-8, TUNEL and western blotting assays, which revealed that CTRP9 increased the activity of HTR8/SVneo cells induced by HG through the alleviation of ER stress. Subsequently, ELISA and western blotting assay results demonstrated that CTRP9 inhibited HG-induced inflammation of the HTR8/SVneo cells by the reduction in ER stress. Finally, the detection of reactive oxygen species, nitric oxide (NO) synthase and NO levels confirmed that CTRP9 inhibited the oxidative stress of HTR8/SVneo cells induced by HG through the reduction of ER stress. Collectively, the results of the present study suggested that CTRP9 may decrease trophoblast cell damage caused by HG through the suppression of ER stress, and therefore, CTRP9 may potentially be a therapeutic target in the treatment of GDM.

Effects of triclosan exposure on placental extravillous trophoblast motility, relevant IGF2/H19 signaling and DNA methylation-related enzymes of HTR-8/SVneo cell line

Triclosan (TCS) is an antimicrobial agent widely used in personal care products and a potential endocrine disruptor chemical (EDC). TCS can pass through the placental barrier. Any influence of EDCs on epigenetic changes of placenta and embryo may bring profound impact on later health. This study aimed to investigate the effects of TCS exposure on cell proliferation and migration, and the expression of imprinted genes IGF2/H19 and DNA methylation-related enzymes in human placental extravillous trophoblast cell line HTR-8/SVneo. After exposure to TCS levels of 0 (DMSO Control), 10−11, 10−10, 10−9, 10−8, 10−7, 10−6, 10−5, 3 × 10−5, 6 × 10−5, 10−4 M and incubated for up to 36 h, cell proliferation and migration were examined by CCK-8, EdU incorporation assay and wound healing assay; the mRNA levels of IGF2, H19, DNA methyltransferases (Dnmt3a, Dnmt3b and Dnmt1), ten-eleven translocation enzymes (Tet1, Tet2 and Tet3) and IGF2 Receptor (IGF2R) were analyzed by qRT-PCR. The protein levels of IGF2 were measured by Western blot and ELISA. The cell viability turned to decline at TCS treatment of 3 × 10−5 M and above (all p < 0.05, compared to the DMSO Control). The cell migration decreased at TCS 10−5 and 3 × 10−5 M treatment (p < 0.05), but consistently unchanged at low dose of TCS from 10−9 to 10−7 M (p > 0.05). TCS treatments below cytotoxicity doses (< 10−5 M) did not significantly alter the mRNA levels of IGF2, Dnmt1, Dnmt3a, Dnmt3b, Tet1, Tet2 and Tet3, compared to DMSO Control treatment (all p > 0.05). The transcription level of H19 was up-regulated by TCS at 3 × 10−5 M. TCS at 10−7 and 6 × 10−5 M increased the protein level of IGF2 in cell supernatant. Our data suggest that high TCS exposure may suppress HTR-8/SVneo cells viability and migration, increase H19 gene expressions and IGF2 protein secretion. The exact mechanism of TCS action in human trophoblast needs further studies.

Toxicity of anticancer drugs in human placental tissue explants and trophoblast cell lines

The application of anticancer drugs during pregnancy is associated with placenta-related adverse pregnancy outcomes. Therefore, it is important to study placental toxicity of anticancer drugs. The aim of this study was to compare effects on viability and steroidogenesis in placental tissue explants and trophoblast cell lines. Third trimester placental tissue explants were exposed for 72 h (culture day 4–7) to a concentration range of doxorubicin, paclitaxel, cisplatin, carboplatin, crizotinib, gefitinib, imatinib, or sunitinib. JEG-3, undifferentiated BeWo, and syncytialised BeWo cells were exposed for 48 h to the same drugs and concentrations. After exposure, tissue and cell viability were assessed and progesterone and estrone levels were quantified in culture medium. Apart from paclitaxel, all compounds affected both cell and tissue viability at clinically relevant concentrations. Paclitaxel affected explant viability moderately, while it reduced cell viability by 50% or more in all cell lines, at 3–10 nM. Doxorubicin (1 µM) reduced viability in explants to 83 ± 7% of control values, whereas it fully inhibited viability in all cell types. Interference with steroid release in explants was difficult to study due to large variability in measurements, but syncytialised BeWo cells proved suitable for this purpose. We found that 1 µM sunitinib reduced progesterone release to 76 ± 6% of control values, without affecting cell viability. While we observed differences between the models for paclitaxel and doxorubicin, most anticancer drugs affected viability significantly in both placental explants and trophoblast cell lines. Taken together, the placenta should be recognized as a potential target organ for toxicity of anticancer drugs.

1336-P: Trimethylamine N-Oxide Inhibits the Formation of Neutrophil Extracellular Traps to Regulate Placental Development in Gestational Diabetes Mellitus

Objective: Trimethylamine N-oxide (TMAO) is associated with risk of gestational diabetes mellitus (GDM), and TMAO levels in peripheral/cord blood of GDM mothers increased. Diabetes primes neutrophils to produce neutrophil extracellular traps (NETs), but it has not been reported in GDM. We determined the relationship between NETs and GDM, and explored potential role of TMAO. Methods: Maternal peripheral blood was collected during OGTT tests, and cord blood and placenta were collected during delivery. Plasma concentrations of cell-free double-stranded DNA (dsDNA) were compared between GDM and control mothers and association analysis was performed. Expression of myeloperoxidase (MPO) in placental tissues of GDM and control mothers was examined. Neutrophils from the blood of healthy donors were used to observe effects of TMAO on NETs formation. The effect of TMAO on human placental extravillous trophoblast cell line HTR-8/Svneo was examined. Results: Compared with controls, plasma concentrations of dsDNA in peripheral blood and cord blood were significantly increased in GDM mothers. Association analysis found that concentrations of dsDNA in peripheral and cord blood plasma were positively correlated with BMI and blood glucose levels, but not blood pressure. In addition, the placental thickness was positively correlated with dsDNA levels in cord blood plasma. MPO expression in the placental tissues of GDM mothers was also significantly higher than that of control mothers. TMAO-treated neutrophils could resist the formation of NETs stimulated by PMA or LPS, and TMAO promotes the proliferation, migration, invasion and angiogenesis of the cells. Conclusion: The formation of NETs was increased in GDM, and was positively correlated with BMI and blood glucose. TMAO could inhibit NETs formation and promote invasion and angiogenesis of human placental trophoblast cells, which may be involved in the development of the placenta. Disclosure X. Lin: None. X. He: None. X. Xiao: None.

Effects of Modified Lipoproteins on Human Trophoblast Cells-A Role in Preeclampsia in Pregnancies Complicated by Diabetes

Preeclampsia (PE) complicates 2-8% of pregnancies worldwide. In women with diabetes, the risk for PE is substantially increased by approximately 4 fold. Evidence indicates that an increased release of two anti-angiogenic factors, soluble fms-like tyrosine kinase (sFlt-1) and soluble endoglin (sEng) from placental trophoblasts into the maternal circulation promotes endothelial dysfunction associated with PE. In this study, we investigated sFlt-1 and sEng release from the human placental trophoblast cell line, HTR8/SVneo, in response to modified lipoproteins and/or elevated glucose. HTR8/SVneo cells were exposed to native low-density lipoprotein (N-LDL) vs. ’highly-oxidized glycated’ LDL (HOG-LDL) (50 µg protein/ml) for 24h, with and without pre-treatment with 30mM glucose for 72h. The mRNA expressions of sFlt-1 isoforms (sFlt-1-i13, sFlt-1-e15a), endoglin and MMP-14 were measured by RT-PCR, and levels of sFlt-1 and sEng in cell supernatant were determined by ELISA. Compared with N-LDL, HOG-LDL increased the mRNA expression of sFlt-1-i13 (2.0 fold, p&amp;lt;0.05), sFlt-1-e15a (1.9 fold, p&amp;lt;0.01), endoglin (1.5 fold, p&amp;lt;0.05) and MMP-14 (1.8 fold, p&amp;lt;0.05). HOG-LDL increased the levels of sFlt-1 and sEng proteins in the supernatant (2.9 fold, p&amp;lt;0.and 3.6 fold, p&amp;lt;0.01, respectively). High glucose alone had no significant effect on sFlt-1 and sEng expressions; however, pre-treatment of high glucose potentiated the effects of HOG-LDL: the supernatant levels of sFlt-1 and sEng were increased by 1.5 fold and 1.8 fold, respectively, compared to HOG-LDL treatment alone (p&amp;lt;0.for both). Exposure of trophoblasts to modified lipoproteins (which accumulate in the tissues of patients with diabetes due to vascular leakage) may contribute to the development of PE in diabetes, which is amplified by the presence of high glucose. These findings may explain, in part, the high risk of PE in women with diabetes. Disclosure R.H. McLeese: None. J. Zhao: None. J. Yu: None. D. Brazil: None. T. Lyons: None.

Effect of Histone Deacetylase Inhibition on the Expression of Multidrug Resistance-associated Protein 2 in a Human Placental Trophoblast Cell Line.

Background:Placental multidrug resistance-associated protein 2 (MRP2), encoded by ABCC2 gene in human, plays a significant role in regulating drugs’ transplacental transfer rates. Studies on placental MRP2 regulation could provide more therapeutic targets for individualized and safe pharmacotherapy during pregnancy. Currently, the roles of epigenetic mechanisms in regulating placental drug transporters are still unclear. This study aimed to investigate the effect of histone deacetylases (HDACs) inhibition on MRP2 expression in the placental trophoblast cell line and to explore whether HDAC1/2/3 are preliminarily involved in this process.Methods:The human choriocarcinoma-derived trophoblast cell line (Bewo cells) was treated with the HDAC inhibitors-trichostatin A (TSA) at different concentration gradients of 0.5, 1.0, 3.0, and 5.0 μmol/L. Cells were harvested after 24 and 48 h treatment. Small interfering RNA (siRNA) specific for HDAC1/HDAC2/HDAC3 or control siRNA was transfected into cells. Total HDAC activity was detected by colorimetric assay kits. HDAC1/2/3/ABCC2 messenger RNA (mRNA) and protein expressions were determined by real-time quantitative polymerase chain reaction and Western-blot analysis, respectively. Immunofluorescence for MRP2 protein expression was visualized and assessed using an immunofluorescence microscopy and ImageJ software, respectively.Results:TSA could inhibit total HDAC activity and HDAC1/2/3 expression in company with increase of MRP2 expression in Bewo cells. Reduction of HDAC1 protein level was noted after 24 h of TSA incubation at 1.0, 3.0, and 5.0 μmol/L (vs. vehicle group, all P < 0.001), accompanied with dose-dependent induction of MRP2 expression (P = 0.045 for 1.0 μmol/L, P = 0.001 for 3.0 μmol/L, and P < 0.001 for 5.0 μmol/L), whereas no significant differences in MRP2 expression were noted after HDAC2/3 silencing. Fluorescent micrograph images of MRP2 protein were expressed on the cell membrane. The fluorescent intensities of MRP2 in the control, HDAC2, and HDAC3 siRNA-transfected cells were week, and no significant differences were noticed among these three groups (all P > 0.05). However, MRP2 expression was remarkably elevated in HDAC1 siRNA-transfected cells, which displayed an almost 3.19-fold changes in comparison with the control siRNA-transfected cells (P < 0.001).Conclusions:HDACs inhibition could up-regulate placental MRP2 expression in vitro, and HDAC1 was probably to be involved in this process.

Cytotoxicity of Endocytosis and Efflux Inhibitors in the BeWo Cell Line.

AimsThe purpose of this study was to determine the cell viability and cytotoxicity of various endocytosis and efflux inhibitors which can be used to determine transport and uptake mechanisms in the BeWo (b30 clone) human placental trophoblast cell line. Ethanol and dimethylsulfoxide (DMSO) were also studied since they are often used as cosolvents for administration of these inhibitors.MethodologyThe water-soluble tetrazolium-1 (WST-1) assay was used to quantify cell viability and the lactate dehydrogenase (LDH) assay was used to determine cytotoxicity.ResultsBy the WST-1 assay, reduced cell viability was observed following 4 hours of exposure to chlorpromazine (10 μg/mL), colchicine (1 mM), filipin (3 μg/mL), gentamicin (2 mM), GF120918 (1 μM), methyl-β-cyclodextrin (5 mM), and verapamil (100 μM). By the LDH assay, however, no cytotoxicity was observed after 4 hours of exposure to the aforementioned compounds. Amiloride (500 μM), ethanol (up to 0.1% v/v), and DMSO (up to 0.1% v/v) did not reduce cell viability nor induce cytotoxicity.ConclusionThis information is valuable when selecting potential inhibitors of endocytosis and efflux and the selection of time points for mechanistic studies.

The effect of histone deacetylase inhibition on the expression of P-glycoprotein in human placental trophoblast cell lines

IntroductionsPlacental P-glycoprotein (P-gp), encoded by ABCB1 gene in human, plays a significant role in regulating drugs' transplacental transfer rates. Investigations on placental P-gp regulation could provide more therapeutic targets for individualized and safe pharmacotherapy during pregnancy. Currently, the epigenetic control of placental P-gp is rare. This study aimed to investigate the effect of histone deacetylases (HDACs) inhibition on P-gp expression in placental trophoblast cell lines and to explore whether HDAC1/2/3 was involved in this process preliminarily. MethodsHuman placental trophoblast cell lines (Bewo and JAR) were treated with two different HDAC inhibitors-suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA) at different concentration gradients of 0.5, 1.0, 3.0 and 5.0 μM. Cells were harvested after 24, 48, and 72 h treatment. Total HDAC activity was detected by colorimetric assay Kits. HDAC1/2/3/ABCB1 mRNA and protein expressions were determined by real-time quantitative PCR and western-blot, respectively. Pearson correlation analysis test was performed to explore the relationship between HDAC1/2/3 mRNA and ABCB1 mRNA expression. ResultsSAHA and TSA could inhibit total HDAC activity and placental HDAC1/2/3 expression both in Bewo and JAR, but displayed a transient induction of HDAC mRNA or protein level after being treated at low dosage or prolonged exposure to drugs. Discordance in HDAC mRNA and protein expression was also observed. Placental P-gp expression was significantly induced in company with HDACs inhibition. There was a significant negative linear relationship between HDAC1/2 mRNA and ABCB1 mRNA expression. ConclusionsHDACs inhibition could up-regulate placental P-gp expression in trophoblast cells, and HDAC1/2 was most likely to be involved in this process.

Triazole fungicide tebuconazole disrupts human placental trophoblast cell functions

Triazole fungicides are one of the top ten classes of current-use pesticides. Although exposure to triazole fungicides is associated with reproductive toxicity in mammals, limited information is available regarding the effects of triazole fungicides on human placental trophoblast function. Tebuconazole (TEB) is a common triazole fungicide that has been extensively used for fungi control. In this work, we showed that TEB could reduce cell viability, disturb normal cell cycle distribution and induce apoptosis of human placental trophoblast cell line HTR-8/SVneo (HTR-8). Bcl-2 protein expression decreased and the level of Bax protein increased after TEB treatment in HTR-8 cells. The results demonstrated that this fungicide induced apoptosis of trophoblast cells via mitochondrial pathway. Importantly, we found that the invasive and migratory capacities of HTR-8 cells decreased significantly after TEB administration. TEB altered the expression of key regulatory genes involved in the modulation of trophoblast functions. Taken together, TEB suppressed human trophoblast invasion and migration through affecting the expression of protease, hormones, angiogenic factors, growth factors and cytokines. As the invasive and migratory abilities of trophoblast are essential for successful placentation and fetus development, our findings suggest a potential risk of triazole fungicides to human pregnancy.

Deleterious effects of benomyl and carbendazim on human placental trophoblast cells.

Benomyl and carbendazim are benzimidazole fungicides that are used throughout the world against a wide range of fungal diseases of agricultural products. There is as yet little information regarding the toxicity of benzimidazole fungicides to human placenta. In this study, we utilized human placental trophoblast cell line HTR-8/SVneo (HTR-8) to access the toxic effects of benomyl and carbendazim. Our data showed that these two fungicides decreased cell viability and the percentages of cells in G0/G1 phase, as well as induced apoptosis of HTR-8 cells. The invasion and migration of HTR-8 cells were significantly inhibited by benomyl and carbendazim. We further found that benomyl and carbendazim altered the expression of protease systems (MMPs/TIPMs and uPA/PAI-1) and adhesion molecules (integrin α5 and β1) in HTR-8 cells. Our present study firstly shows the deleterious effects of benomyl and carbendazim on placental cells and suggests a potential risk of benzimidazole fungicides to human reproduction.

Bioinformatic Analysis of Benzo-α-Pyrene-Induced Damage to the Human Placental Insulin-Like Growth Factor-1 Gene

Intrauterine growth restriction (IUGR) has been associated with exposure to polyaromatic hydrocarbons (PAHs) which are released in the combustion of oil, fuel, gas, garbage, and tobacco. Pregnant women exposed to PAHs are at risk of the effects of these environmental toxins; for example, benzo-α-pyrene (BαP) is able to enter the blood stream and could contribute to IUGR or other developmental abnormalities via effects on the placental cells. Since IUGR has been associated with decreased cord blood concentrations of immunoreactive insulin-like growth factor 1 (ir-IGF-1) and IUGR has been associated with disordered development and fetal programming, we tested the effects of BαP on human placental trophoblast cells in culture. IGF-1 expression and activation was studied using an immortalized human placental trophoblast cell line (HTR-8). The cells were treated with vehicle control or 1 µmol/L BαP, or 5 µmol/L BαP for 12 hours. RNA was extracted and the exons of IGF-1 were amplified using reverse transcriptase-polymerase chain reaction (RT-PCR). The ir-IGF-1 expression levels were compared using gel electrophoresis. The PCR products were sequenced, and levels of mutation were measured with comparative sequence analysis. A computational protein analysis (computer simulation) was performed in order to assess the potential impact of BαP-associated mutation on IGF-1 protein function. The IGF-1 expression decreased considerably in BαP-treated cells relative to untreated controls (P < .05), also in a dose-dependent manner. Comparative sequence analysis indicated that the level of BαP exposure correlated with the percentage of base pair mutations in IGF-1 nucleotide sequences for both treatment groups (P < .05). Shifts were observed in the open reading frame, indicating a possible change in the IGF-1 start codon. Protein folding simulation analysis indicated that the base pair changes induced by BαP weakened IGF-1-IGF binding protein (IGFBP) interaction. In concordance with the previous findings, exposure of human placental trophoblast cells to BαP exposure results in reduction of IGF-1 expression and base pair mutations. The direct action of BαP on the placenta indicates that it may not be necessary for BαP to access other maternal tissues in order for gene abnormalities to occur. Given that PAHs are known to work through aryl hydrocarbon hydrolase (AHH), these results are likely due to the presence of AHH in HTR cells. Computational modeling of BαP actions on IGF1, substrate-ligand binding, supports the biological premise of this work and underlines the need to determine actual biological effects rather than equating immune to bioactivity of IGF1.

Downregulation of SPARC Expression Inhibits the Invasion of Human Trophoblast Cells In Vitro

Successful pregnancy depends on the precise regulation of extravilloustrophoblast (EVT) invasion into the uterine decidua. SPARC (secreted protein acidic and rich in cysteine) is a matricellular glycoprotein that plays critical roles in the pathologies associated with obesity and diabetes, as well as tumorigenesis. The objective of this study was to investigate the role of SPARC in the process of trophoblast invasion which shares many similarities with tumor cell invasion. By Western blot, higher expression of SPARC was observed in mouse brain, ovary and uterus compared to other mouse tissues. Immunohistochemistry analysis revealed a spatio-temporal expression of SPARC in mouse uterus in the periimplantation period. At the implantation site of d8 pregnancy, SPARC mainly accumulated in the secondary decidua zone (SDZ), trophoblast cells and blastocyst. The expression of SPARC was also detected in human placental villi and trophoblast cell lines. In a Matrigel invasion assay, we found SPARC-specific RNA interference significantly reduced the invasion of human extravilloustrophoblast HTR8/SVneo cells. Microarray analysis revealed that SPARC depletion upregulated the expression of interleukin 11 (IL11), KISS1, insulin-like growth factor binding protein 4 (IGFBP4), collagen type I alpha 1 (COLIA1), matrix metallopeptidase 9 (MMP9), and downregulated the expression of the alpha polypeptide of chorionic gonadotropin (CGA), MMP1, gap junction protein alpha 1 (GJA1), et al. The gene array result was further validated by qRT-PCR and Western blot. The present data indicate that SPARC may play an important role in the regulation of normal placentation by promoting the invasion of trophoblast cells into the uterine decidua.

Regulation of pregnancy-associated plasma protein A2 (PAPPA2) in a human placental trophoblast cell line (BeWo)

BackgroundPregnancy-associated plasma protein A2 (PAPPA2) is an insulin-like growth factor-binding protein (IGFBP) protease expressed at high levels in the placenta and upregulated in pregnancies complicated by preeclampsia and HELLP (Hemolytic anemia, Elevated Liver enzymes, and Low Platelet count) syndrome. However, it is unclear whether elevated PAPPA2 expression causes abnormal placental development, or whether upregulation compensates for placental pathology. In the present study, we investigate whether PAPPA2 expression is affected by hypoxia, oxidative stress, syncytialization factors or substances known to affect the expression of PAPPA2's paralogue, PAPPA.MethodsBeWo cells, a model of placental trophoblasts, were treated with one of the following: hypoxia (2% O2), oxidative stress (20 microM hydrogen peroxide), forskolin (10 microM and 100 microM), TGF-beta (10 and 50 ng/mL), TNF-alpha (100 ng/mL), IL-1beta (100 ng/mL) or PGE2 (1 microM). We used quantitative RT-PCR (qRT-PCR) to quantify the mRNA levels of PAPPA2, as well as those of PAPPA and ADAM12 since these proteases have similar substrates and are also highly expressed in the placenta. Where we observed significant effects on PAPPA2 mRNA levels, we tested for effects at the protein level using an in-cell Western assay.ResultsHypoxia, but not oxidative stress, caused a 47-fold increase in PAPPA2 mRNA expression, while TNF-alpha resulted in a 6-fold increase, and both of these effects were confirmed at the protein level. PGE2 resulted in a 14-fold upregulation of PAPPA2 mRNA but this was not reflected at the protein level. Forskolin, TGF-beta and IL-1beta had no significant effect on PAPPA2 mRNA expression. We observed no effects of any treatment on PAPPA or ADAM12 expression.ConclusionOur study demonstrates that factors previously known to be highly expressed in preeclamptic placentae (PGE2 and TNF-alpha), contribute to the upregulation of PAPPA2. Hypoxia, known to occur in preeclamptic placentae, also increased PAPPA2 expression. These results are consistent with the hypothesis that PAPPA2 is upregulated as a consequence of placental pathology, rather than elevated PAPPA2 levels being a cause of preeclampsia.

Multifunctional angiogenic factors: add GnRH to the list. Focus on “Gonadotropin-releasing hormone-regulated chemokine expression in human placentation”

the historical view that angiogenesis is governed by the action of a few dominant trophic factors, such as VEGF, FGF, and transforming growth factor-β (TGF-β), has steadily eroded over the past two decades to give rise to the vision of a much more dynamic regulation in which angiogenesis is

Membrane trafficking of CD98 and its ligand galectin 3 in BeWo cells − implication for placental cell fusion

CD98 heavy chain (CD98hc), expressed at high levels in developing human trophoblasts, is an integral membrane protein with multiple N-linked glycosylation sites and known to be important for cell fusion, adhesion, and amino acid transport. Western blotting and flow cytometry were used to study the effect of brefeldin A, an inhibitor of protein translocation through the Golgi, on CD98hc in the human placental trophoblast cell line BeWo. Although brefeldin A treatment caused increased cell surface expression of CD98hc, a novel partially glycosylated form of the protein was found and, concomitantly, cell fusion was reduced. Western blotting showed that CD98 and galectin 3, a proposed ligand for the glycosylated extracellular domain of CD98hc, co-immunoprecipitated, and double-label immuno-electron microscopy confirmed that CD98hc associated with galectin 3. Furthermore, cell fusion was reduced (specifically) by the disaccharide lactose, a known ligand for the carbohydrate recognition domain of galectin 3, suggesting that the association was functional. Taken together, the data suggest that N-glycosylation of CD98 and subsequent interaction with galectin 3 is critical for aspects of placental cell biology, and provides a rationale for the observation that, in the mouse, truncation of the CD98hc extracellular domain leads to early embryonic lethality [Tsumura H, Suzuki N, Saito H, Kawano M, Otake S, Kozuka Y, Komada H, Tsurudome M & Ito Y (2003) Biochem Biophys Res Commun 308, 847-851].

Differential effect of cross-linking the CD98 heavy chain on fusion and amino acid transport in the human placental trophoblast (BeWo) cell line

CD98 (otherwise known as 4F2) is an integral membrane protein with multiple functions including amino acid transport, integrin activation, cell fusion and cell activation. The molecular mechanisms coordinating these multiple functions remain unclear. We have studied CD98 heavy chain (hc) function in a human placental trophoblast cell line (BeWo). We show that cross-linking of CD98hc by incubation of cells in the presence of functional monoclonal antibodies causes cellular re-distribution of the protein from the cytoplasm to the plasma membrane as measured by flow cytometry, western blotting and quantitative immuno-electron microscopy. The latter technique also indicated that CD98hc is trafficked between cell surface and cytoplasmic pools in vesicles. Increased cell surface CD98 correlates with increased cellular fusion in BeWo cells. In addition, we show reduced LAT 1 surface expression and neutral amino acid transport in the presence of the CD98 mabs. The results thus suggest that the function of CD98 in cell fusion is distinct from its role in cellular nutrient delivery.

Phosphorylation of the Norepinephrine Transporter at Threonine 258 and Serine 259 Is Linked to Protein Kinase C-mediated Transporter Internalization

Recently, we have demonstrated the phosphorylation- and lipid raft-mediated internalization of the native norepinephrine transporter (NET) following protein kinase C (PKC) activation (Jayanthi, L. D., Samuvel, D. J., and Ramamoorthy, S. (2004) J. Biol. Chem. 279, 19315-19326). Here we tested an hypothesis that PKC-mediated phosphorylation of NET is required for transporter internalization. Phosphoamino acid analysis of 32P-labeled native NETs from rat placental trophoblasts and heterologously expressed wild type human NET (WT-hNET) from human placental trophoblast cells revealed that the phorbol ester (beta-PMA)-induced phosphorylation of NET occurs on serine and threonine residues. Beta-PMA treatment inhibited NE transport, reduced plasma membrane hNET levels, and stimulated hNET phosphorylation in human placental trophoblast cells expressing the WT-hNET. Substance P-mediated activation of the G alpha(q)-coupled human neurokinin 1 (hNK-1) receptor coexpressed with the WT-hNET produced effects similar to beta-PMA via PKC stimulation. In striking contrast, an hNET double mutant harboring T258A and S259A failed to show NE uptake inhibition and plasma membrane redistribution by beta-PMA or SP. Most interestingly, the plasma membrane insertion of the WT-hNET and hNET double mutant were not affected by beta-PMA. Although the WT-hNET showed increased endocytosis and redistribution from caveolin-rich plasma membrane domains following beta-PMA treatment, the hNET double mutant was completely resistant to these PKC-mediated effects. In addition, the PKC-induced phosphorylation of hNET double mutant was significantly reduced. In the absence of T258A and S259A mutations, alanine substitution of all other potential phosphosites within the hNET did not block PKC-induced phosphorylation and down-regulation. These results suggest that Thr-258 and Ser-259 serve as a PKC-specific phospho-acceptor site and that phosphorylation of this motif is linked to PKC-induced NET internalization.