Syncytiotrophoblast Of Placenta Research Articles

Placental mitochondria central to gestational diabetes pathogenesis?

Placental mitochondria central to gestational diabetes pathogenesis?

AT-rich interactive domain 1A protein expression in normal and pathological pregnancies complicated by preeclampsia.

AT-rich interactive domain 1A (ARID1A, as known as BAF250a) is a subunit of human switch/sucrose nonfermentable chromatin remodeling complex with tumour suppressor function. Mutations of Arid1a have been reported in many human cancers and low expression of this protein has been correlated to a poor prognosis outcome in patients affected by some types of cancer. Although there are many studies regarding ARID1A functions in cancer, little is known about its role in regulating cell differentiation and normal tissues homeostasis. Here, we investigate ARID1A expression in normal placental tissues of first and third trimester of gestation and in pathological placental tissues of pregnancy complicated by preeclampsia (PE) and intrauterine growth restriction (IUGR) to evaluate a possible role of this protein in trophoblast differentiation. We found that ARID1A was specifically expressed in villous and extravillous cytotrophoblastic cells in normal placentas whereas syncytiotrophoblast was negative. Interestingly, ARID1A was expressed in both cytotrophoblastic cells and syncytiotrophoblast in placentas affected by PE and PE-IUGR. Moreover, ARID1A was also present in syncitial knots of pathological placentas. The present results indicate that ARID1A is a good marker of poor trophoblast differentiation in these pathologies, because the significant high positive staining in syncytiotrophoblast nuclei may suggest a poor differentiation of this trophoblast layer due to the cytotrophoblast cells fusion with the syncytiotrophoblast overlaying before arresting their cell cycle.

The SARS-CoV-2 receptor ACE2 expression of maternal-fetal interface and fetal organs by single-cell transcriptome study.

The new type of pneumonia caused by the SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) has been declared as a global public health concern by WHO. As of April 3, 2020, more than 1,000,000 human infections have been diagnosed around the world, which exhibited apparent person-to-person transmission characteristics of this virus. The capacity of vertical transmission in SARS-CoV-2 remains controversial recently. Angiotensin-converting enzyme 2 (ACE2) is now confirmed as the receptor of SARS-CoV-2 and plays essential roles in human infection and transmission. In present study, we collected the online available single-cell RNA sequencing (scRNA-seq) data to evaluate the cell specific expression of ACE2 in maternal-fetal interface as well as in multiple fetal organs. Our results revealed that ACE2 was highly expressed in maternal-fetal interface cells including stromal cells and perivascular cells of decidua, and cytotrophoblast and syncytiotrophoblast in placenta. Meanwhile, ACE2 was also expressed in specific cell types of human fetal heart, liver and lung, but not in kidney. And in a study containing series fetal and post-natal mouse lung, we observed ACE2 was dynamically changed over the time, and ACE2 was extremely high in neonatal mice at post-natal day 1~3. In summary, this study revealed that the SARS-CoV-2 receptor was widely spread in specific cell types of maternal-fetal interface and fetal organs. And thus, both the vertical transmission and the placenta dysfunction/abortion caused by SARS-CoV-2 need to be further carefully investigated in clinical practice.

Syncytiotrophoblast of Placentae from Women with Zika Virus Infection Has Altered Tight Junction Protein Expression and Increased Paracellular Permeability.

The cytotrophoblast of human placenta transitions into an outer multinucleated syncytiotrophoblast (STB) layer that covers chorionic villi which are in contact with maternal blood in the intervillous space. During pregnancy, the Zika virus (ZIKV) poses a serious prenatal threat. STB cells are resistant to ZIKV infections, yet placental cells within the mesenchyme of chorionic villi are targets of ZIKV infection. We seek to determine whether ZIKV can open the paracellular pathway of STB cells. This route is regulated by tight junctions (TJs) which are present in the uppermost portion of the lateral membranes of STB cells. We analyzed the paracellular permeability and expression of E-cadherin, occludin, JAMs –B and –C, claudins -1, -3, -4, -5 and -7, and ZO-1, and ZO-2 in the STB of placentae from ZIKV-infected and non-infected women. In ZIKV-infected placentae, the pattern of expression of TJ proteins was preserved, but the amount of claudin-4 diminished. Placentae from ZIKV-infected women were permeable to ruthenium red, and had chorionic villi with a higher mean diameter and Hofbauer hyperplasia. Finally, ZIKV added to the basolateral surface of a trophoblast cell line reduced the transepithelial electrical resistance. These results suggest that ZIKV can open the paracellular pathway of STB cells.

The clinical course and pathophysiological investigation of adolescent gestational diabetes insipidus: a case report

BackgroundGestational diabetes insipidus (GDI) is a rare endocrine complication during pregnancy that is associated with vasopressinase overproduction from the placenta. Although increased vasopressinase is associated with placental volume, the regulation of placental growth in the later stage of pregnancy is not well known.Case presentationA 16-year-old pregnant woman was urgently transferred to our hospital because of threatened premature labor when the Kumamoto earthquakes hit the area where she lived. During her hospitalization, she complained of gradually increasing symptoms of polyuria and polydipsia. The serum level of arginine vasopressin (AVP) was 1.7 pg/mL, which is inconsistent with central DI. The challenge of diagnostic treatment using oral 1-deamino-8-D-AVP (DDAVP) successfully controlled her urine and allowed for normal delivery. DDAVP tablets were not necessary to control her polyuria thereafter. Based on these observations, clinical diagnosis of GDI was confirmed. Pathophysiological analyses revealed that vasopressinase expression was more abundant in the GDI patient’s syncytiotrophoblast in placenta compared with that in a control subject. Serum vasopressinase was also observed during gestation and disappeared soon after delivery. Vasopressinase is reportedly identical to oxytocinase or insulin regulated aminopeptidase (IRAP), which is an abundant cargo protein associated with the glucose transporter 4 (GLUT4) storage vesicle. Interestingly, the expression and subcellular localization of GLUT4 appeared to occur in a vasopressinase (IRAP)-dependent manner.ConclusionBecause placental volume may be associated with vasopressinase overproduction in GDI, vasopressinase (IRAP)/GLUT4 association appears to contribute to the growth of placenta in this case.

Vascular endothelial growth factor expression in placenta of hypertensive disorder in pregnancy.

Hypertensive disorder in pregnancy (HDP) represents the most common medical complication in pregnancy. It is the leading cause of maternal and perinatal mortality and morbidity. Vascular endothelial growth factor (VEGF) stimulates vascular endothelial cell growth, survival, and proliferation, and they are known to be expressed in human placenta. The aim of this study was to determine the VEGF expression in the placenta of hypertensive and normotensive patients. This is a retrospective, cross-sectional study from January 1, 2015 to December 31, 2015. A total of 30 placentae comprised of 15 hypertensive and 15 normotensive cases were assessed. VEGF expression in placenta was assessed by immunohistochemistry, and the number of syncytial knots was counted. Our study showed an increased syncytial knot formation in the placenta of hypertensive mothers. VEGF expression was seen in syncytiotrophoblasts of 14 of the hypertensive cases (14/15, 93.3%), while only two of the normotensive cases were positive (2/15, 13.3%). There were no statistically significant differences in VEGF expression in other placenta cells, that is, cytotrophoblasts (P = 1.0), decidual cells (0.1394), maternal endothelial cells (0.5977), and fetal endothelial cells (P = 1.0). This study showed an increased number of syncytial knots is a consistent histological finding in the placenta of patient with HDP. VEGF expression was significantly increased in syncytiotrophoblasts in placenta of hypertensive group, and it could be used as a biomarker for hypertension.

Megalin Is Predominantly Observed in Vesicular Structures in First and Third Trimester Cytotrophoblasts of the Human Placenta.

The membrane receptor megalin is crucial for normal fetal development. Besides its expression in the developing fetus, megalin is also expressed in the human placenta. Similar to its established function in the kidney proximal tubules, placental megalin has been proposed to mediate uptake of vital nutrients. However, details of megalin expression, subcellular localization, and function in the human placenta remain to be established. By immunohistochemical analyses of first trimester and term human placenta, we showed that megalin is predominantly expressed in cytotrophoblasts, the highly proliferative cells in placenta. Only limited amounts of megalin could be detected in syncytiotrophoblasts and least in term placenta syncytiotrophoblasts. Immunocytochemical analyses furthermore showed that placental megalin associates with structures of the endolysosomal apparatus. Combined, our results clearly place placental megalin in the context of endocytosis and trafficking of ligands. However, due to the limited expression of megalin in syncytiotrophoblasts, especially in term placenta, it appears that the main role for placental megalin is not to mediate uptake of nutrients from the maternal bloodstream, as previously proposed. In contrast, our results point toward novel and complex functions for megalin in the cytotrophoblasts. Thus, we propose that the perception of placental megalin localization and function should be revised.

РОЛЬ ЭСТРАДИОЛА В ПОДДЕРЖАНИИ ФЕТОПЛАЦЕНТАРНОЙ СИСТЕМЫ

The aim of the study is to define the role of abnormalities in the formation of estriol hormones in the development of hormonal dysfunction of fetoplacental system. There were examined 39 placentas from women with exacerbation of chronic cytomegalovirus infection at the third trimester of pregnancy and IgG antibody titer 1:1600 and 30 placentas from women with latent CMV infection and titer 1:400. The activity of androstenedione dehydrogenase was found out with histochemical method on cryostat sections of freshly frozen tissues of placentas by Lloyd’s method. The assessment of intensiveness of histochemical reaction was done with cytophotometric method by Scion program. Estradiol in homogenate of placenta was measured with immune-enzyme method. The quantity of nuclei of placenta syncytiotrophoblast in the state of apoptosis was done with cytophotometric method on paraffin sections stained by ISEL method. By the results of the study the exacerbation of CMV infection at the third trimester of pregnancy leads to the decrease of intensiveness of histochemical reaction in placentas to androstenedione dehydrogenase till 32.1±2.88 pixel/mcm2 (at the latent course it is 54.2±4.31 pixel/mcm2, р<0.001), and in homogenate of placenta to the decrease of estradiol till 18443.2±117.53 pmole/l (at the latent course of the disease it is 28977.7±158.13 pmole/l, p<0.001), on paraffin sections in syncytiotrophoblast by the increase of nuclei number in the state of apoptosis till 5.0±0.03% (at latent course of the disease it is 1.2±0.001%, р<0.001) and vacuole formation, which leads to destructive damages of syncytiotrophoblast cytoplasm. The obtained results prove that the exacerbation of CMV infection at the third trimester of pregnancy causes the decrease of estriol hormones formation, which is accompanied by the damage of morphostructure and exchange processes in cell elements of placenta.

Increased expression of high mobility group box 1 (HMGB1) in the cytoplasm of placental syncytiotrophoblast from preeclamptic placentae

BackgroundPreeclampsia is a pregnancy-specific disorder characterised by an inappropriate maternal inflammatory response during pregnancy. High mobility group box 1 (HMGB1) was originally characterised as a nuclear protein but when released into the extracellular environment following necrotic cell death, it is proinflammatory. HMGB1 is expressed in the syncytiotrophoblast of human placenta. Higher levels of uric acid are reported in preeclampsia. The aim of this study was to investigate whether the expression of HMGB1differed between early onset and late onset preeclampsia or severe and mild preeclampsia and whether its expression correlated with the levels of uric acid. Methods74 preeclamptic placentae and 110 normotensive placentae were included in this study. The levels of uric acid in women with preeclampsia were measured. The expression of HMGB1 in preeclamptic placentae or in first trimester and term placentae that had been treated with uric acid was measured. ResultsHMGB1 was expressed predominantly in the syncytiotrophoblast of the placenta and the expression of HMGB1 in the cytoplasm of the syncytiotrophoblast was significantly increased in both severe preeclampsia and early onset preeclampsia compared to normotensive pregnancies. The circulating levels of uric acid were significantly increased in preeclampsia and correlated with the expression of HMGB1. Increased levels of HMGB1 were significantly correlated with the severity and the time of onset of preeclampsia, but pathologic levels of uric acid did not increase the expression of HMGB1. ConclusionOur data provides a better understanding of the function of HMGB1, a danger molecule in the pathogenesis of preeclampsia.

Placental endoplasmic reticulum stress negatively regulates transcription of placental growth factor via ATF4 and ATF6β: implications for the pathophysiology of human pregnancy complications.

Low maternal circulating concentrations of placental growth factor (PlGF) are one of the hallmarks of human pregnancy complications, including fetal growth restriction (FGR) and early‐onset pre‐eclampsia (PE). Currently, PlGF is used clinically with other biomarkers to screen for high‐risk cases, although the mechanisms underlying its regulation are largely unknown. Placental endoplasmic reticulum (ER) stress has recently been found to be elevated in cases of FGR, and to an even greater extent in early‐onset PE complicated with FGR. ER stress activates the unfolded protein response (UPR); attenuation of protein translation and a reduction in cell growth and proliferation play crucial roles in the pathophysiology of these complications of pregnancy. In this study, we further identified that ER stress regulates release of PlGF. We first observed that down‐regulation of PlGF protein was associated with nuclear localization of ATF4, ATF6α and ATF6β in the syncytiotrophoblast of placentae from PE patients. Transcript analysis showed a decrease of PlGF mRNA, and an increase from genes encoding those UPR transcription factors in placentae from cases of early‐onset PE, but not of late‐onset (>34 weeks) PE, compared to term controls. Further investigations indicated a strong correlation between ATF4 and PlGF mRNA levels only (r = − 0.73, p < 0.05). These results could be recapitulated in trophoblast‐like cells exposed to chemical inducers of ER stress or hypoxia–reoxygenation. The stability of PlGF transcripts was unchanged. The use of small interfering RNA specific for transcription factors in the UPR pathways revealed that ATF4 and ATF6β, but not ATF6α, modulate PlGF transcription. To conclude, ATF4 and ATF6β act synergistically in the negative regulation of PlGF mRNA expression, resulting in reduced PlGF secretion by the trophoblast in response to stress. Therefore, these results further support the targeting of placental ER stress as a potential new therapeutic intervention for these pregnancy complications. © 2015 The Authors. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Transcription factors E2F1 and E2F3 are expressed in placenta but do not regulate MMP14

IntroductionPreeclampsia is a serious complication of pregnancy for which there are no efficacious medical treatments. Soluble endoglin is as an anti-angiogenic factor that contributes to the pathogenesis of the disease, however little is known about its molecular regulation in placenta. Recent data has demonstrated E2F transcription factors directly regulate MMPs in metastatic disease. Of particular interest was the capacity of E2F1 and E2F3 to up-regulate MMP14, a protease that cleaves and releases soluble endoglin from placenta.The aim of this study was to characterize E2F1 and E2F3 in preeclamptic placenta and assess whether silencing affects soluble endoglin release. MethodsE2F1 and E2F3 mRNA, protein expression and localization were assessed in severe early onset preeclamptic and preterm control placentas (delivered <34 weeks gestation). E2F siRNA was administered to primary trophoblast and primary endothelial cells and effect on MMP14 mRNA expression and soluble endoglin secretion assessed. ResultsE2F1 and E2F3 were localized to the syncytiotrophoblast. E2F1 was significantly down regulated in severe preeclamptic placentas, while E2F3 was unchanged. Silencing E2F1 did not decrease MMP14 expression in primary trophoblast or endothelial cells. However, E2F1 silencing resulted in a significant increase in soluble endoglin secretion from both cell types, and silencing of E2F3 also significantly increased soluble endoglin release from primary trophoblast. DiscussionThis study demonstrates that E2F1 and E2F3 are present within the syncytiotrophoblast of placenta and that E2F1 is reduced in preeclampsia. Although silencing of either E2F1 or E2F3 does not alter MMP14 expression, both appear to regulate soluble endoglin release.

Increased expression levels of E-cadherin, cytokeratin 18 and 19 observed in preeclampsia were not correlated with disease severity

IntroductionPreeclampsia is a pregnancy-specific disorder and placental factor(s) contribute to the pathogenesis of preeclampsia. Turnover of villous trophoblast is affected by impaired placental perfusion in preeclampsia. Expression and localisation of cadherins and cytokeratins are involved in the pathogenesis of preeclampsia. However, studies describing the associations between cadherins and cytokeratins in preeclampsia are limited. The aim of this study was to investigate the expression of E-cadherin, N-cadherin, cytokeratin 18 and cytokeratin 19 in placentae from women with preeclampsia in order to determine whether their expression differs with disease severity. Methods29 preeclamptic placentae and 25 normotensive placentae were included in this study. The expression of E-cadherin, cytokeratin 18, cytokeratin 19 andN-cadherin was quantified by immunohistochemistry and western blotting. ResultsE-cadherin, cytokeratin 18 and cytokeratin 19 were expressed predominantly in the syncytiotrophoblast of the placenta and the expression of E-cadherin, cytokeratin 18 and cytokeratin 19 was significantly increased in preeclampsia compared to normotensive pregnancies. However, there was no significant difference in expression between severe preeclampsia and mild preeclampsia. In addition, there was no difference in the expression of N-cadherin between preeclampsic and normotensive pregnancies. DiscussionOur data demonstrated increased expression of E-cadherin, cytokeratin 18 and cytokeratin 19 in the syncytiotrophoblast of preeclamptic placentae, but this increase was not correlated with disease severity. ConclusionOur data suggests that E-cadherin and cytokeratins are involved in the pathogenesis of preeclampsia.

United we stand not dividing: The syncytiotrophoblast and cell senescence

The multinucleate syncytiotrophoblast of the human placenta is responsible for transport functions between maternal and fetal blood supplies and is a major site of protein synthesis and steroid production. It is formed by cell fusion of the underlying cytotrophoblast cells. The nuclei of the multinucleate syncytiotrophoblast are non-mitotic yet the mechanism of cell cycle arrest in the syncytiotrophoblast is not known. The recent publication by the group of Krizhanovsky (2013), demonstrates that cell fusion induces cell senescence. The work reported the exciting finding that term placenta syncytiotrophoblast displays markers associated with cellular senescence. Cellular senescence is perhaps best known as a component of aging, a response to stress and an important factor in preventing tumor cell growth. The aforementioned study suggests myriad avenues of investigation in placental biology with intriguing possibilities to furthering our understanding of placental development and aging, health of pregnancy and placental pathologies having their origin in placental stress.

Abstract 275: Tissue Transglutaminase Stabilizes Placental AT1 Receptor and Contributes to Pathophysiology in Preeclampsia

Preeclampsia (PE) is a serious hypertensive disease of pregnancy associated with the presence of the major angiotensin receptor AT1-agnostic autoantibodies (AT1-AAs) that cause the defining PE features when introduced into pregnant mice. To understand AT1-AA-mediated receptor activation in PE, we explored the role of tissue transglutaminases (TG2), the most ubiquitous member of a group of enzymes modifying proteins by catalyzing the formation of ε-(γ-glutamyl)-lysine isopeptide bonds. TG2, a versatile protein that can also function as a G protein, is enriched in the syncytiotrophoblasts of placenta, the key organ in PE pathogenesis. Western blot analysis and IHC-IF double staining initially revealed that TG2 and transglutaminase (TG)-mediated isopeptide modification levels are increased approximately 2X in PE vs normotensive (NT) placental tissue (n=4 or 5, p&lt;0.05). Next, we identified a similar increase in PE plasma TG activity (NT=3.1±0.5, mild PE=5.4±0.6, severe PE=9.1±0.7milliunit/ml, n=26-29, p&lt;0.01), and the increased plasma TG activity is positively correlated with the key disease features including blood pressure and proteinuria (r 2 &gt;0.5, p&lt;0.01). We also found a higher level of AT1 receptor with isopeptide modification in PE placentas by immunoprecipitation and IF colocalization. A pathogenic role for TG2 in PE is suggested by in vivo experiments in which TG inhibitor cystamine, or siRNA-mediated TG2 knockdown, significantly attenuated AT1-AA-induced PE features in pregnant mice including hypertension (PE=160±6 vs PE+cystamine=133±3mmHg, p&lt;0.01, n=6; PE+control siRNA=161±3 vs PE+ TG2 siRNA=137±7mmHg, p&lt;0.05, n=5-6), proteinuria (PE=133±21 vs PE+cystamine=58±12ng albumin/mg creatine, p&lt;0.01, n=6; PE+control siRNA=102±51 vs PE+ TG2 siRNA=26±6ng albumin/mg creatine, p&lt;0.05, n=4), and placental isopeptide modification. In trophoblasts, AT1-AA stimulation enhanced the interaction between AT1 receptor and TG2, and resulted in increased AT1 receptor stabilization via isopeptide modification, which is further confirmed by mutagenesis studies. Taken together, our results not only identify a pathogenic role of TG2 in PE, but also shed light on a previously unrecognized mechanism of TG2-mediated GPCR stabilization.

In VitroInfection ofTrypanosoma cruziCauses Decrease in Glucose Transporter Protein-1 (GLUT1) Expression in Explants of Human Placental Villi Cultured under Normal and High Glucose Concentrations

Trypanosoma cruzi, the etiologic Chagas' disease agent, induces changes in protein pattern of the human placenta syncytiotrophoblast. The glucose transporter protein-1 (GLUT1) is the primary isoform involved in transplacental glucose transport. We carried out in vitro assays to determine if T. cruzi infection would induce changes in placental GLUT1 protein expression under normal and high concentration of glucose. Using Western blot and immunohistological techniques, GLUT1 expression was determined in normal placental villi cultured under normal or high concentrations of glucose, with or without in vitro T. cruzi infection, for 24 and 48 hours. High glucose media or T. cruzi infection alone reduced GLUT1 expression. A yet more accentuated reduction was observed when infection and high glucose condition took place together. We inform, for the first time, that T. cruzi infection may induce reduction of GLUT1 expression under normal and high glucose concentrations, and this effect is synergic to high glucose concentrations.

Fine-scale quantification of HCG beta gene transcription in human trophoblastic and non-malignant non-trophoblastic tissues

Human chorionic gonadotropin (HCG) is produced by syncytiotrophoblast of placenta. It delays the apoptosis of corpus luteum and functions in implantation. Its possible role in male reproduction has been raised. HCG beta subunit is encoded by CGB, CGB5, CGB7 and CGB8 genes located at 19q13.3 in a common genome cluster with beta subunit non-coding CGB1 and CGB2. We conducted a sensitive quantification and comparison of CGB gene expression in human trophoblastic (blastocysts, n = 6; normal/failed pregnancy, n = 51) and non-malignant non-trophoblastic tissues (15 different tissue types, samples n = 241), by real-time RT-PCR. We showed a wide transcriptional window of CGB genes in normal pregnancy, a significant reduction in recurrent miscarriages, and a high expression (especially CGB1/CGB2) in ectopic and molar pregnancies. Expression was several orders of magnitude lower in the non-placental tissues, with the highest CGB levels being seen in testis, prostate, thymus, skeletal muscle and lung samples. The contribution of CGB1/CGB2 to the summarized expression of six CGB genes was not proportional to their gene dosage: 1/1000 to 1/10,000. An interesting exception was the testis exhibiting a much higher CGB1/CGB2 to total CGB mRNA ratio of approximately one-third, corresponding to gene dosage. In conclusion, the expressional profile of CGB genes, activated already in blastocyst stage, is associated with the status of pregnancy. The presence of CGB transcripts in testes, and in particular CGB1/CGB2 transcripts, may indicate a role in male reproductive tract.

Aquaporin 3 Expression in Human Fetal Membranes and its Up-regulation by Cyclic Adenosine Monophosphate in Amnion Epithelial Cell Culture

The cell membrane water channel protein aquaporins (AQPs) may be important in regulating the intramembranous (IM) pathway of amniotic fluid (AF) resorption. The objective of the present study was to determine whether aquaporin 3 (AQP3) is expressed in human fetal membranes and to further determine if AQP3 expression in primary human amnion cell culture is regulated by second-messenger cyclic adenosine monophosphate (cAMP). AQP3 expression in human fetal membranes of normal term pregnancy was studied by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC). To determine the effect of cAMP on AQP3 expression, primary human amnion cell cultures were treated in either heat-inactivated medium alone (control), or heat-inactivated medium containing: (1) SP-cAMP, a membrane-permeable and phosphodiesterase resistant cAMP agonist, or (2) forskolin, an adenylate cyclase stimulator. Total RNA was isolated and multiplex real-time RT-PCR employed for relative quantitation of AQP3 expression. We detected AQP3 expression in placenta, chorion, and amnion using RT-PCR. Using IHC, we identified AQP3 protein expression in placenta syncytiotrophoblasts and cytotrophoblasts, chorion cytotrophoblasts, and amnion epithelia. In primary amnion epithelial cell culture, AQP3 mRNA significantly increased at 2 hours following forskolin or SP-cAMP, remained elevated at 10 hours following forskolin, and returned to baseline levels by 20 hours following treatment. This study provides evidence of AQP3 expression in human fetal membranes and demonstrates that AQP3 expression in primary human amnion cell culture is up-regulated by second-messenger cAMP. As AQP3 is permeable to water, urea, and glycerol, modulation of its expression in fetal membranes may contribute to AF homeostasis.

Human Latrophilin-2 is Expressed in the Cytotrophoblast and Syncytiotrophoblast of Placenta and in Endothelial Cells

Human Latrophilin-2 is Expressed in the Cytotrophoblast and Syncytiotrophoblast of Placenta and in Endothelial Cells

Human Latrophilin-2 is Expressed in the Cytotrophoblast and Syncytiotrophoblast of Placenta and in Endothelial Cells

Latrophilin-2 is a member of the family of adhesion-GPCRs that is characterised by a long N-terminus which contains motifs identified in proteins involved in cell adhesion. We were interested in determining the expression pattern of human latrophilin-2 and to perform a biochemical characterisation of this protein. The expression pattern of latrophilin-2 was analysed in human organs, tissues and cell lines. RT-PCR analyses detect a very strong signal for latrophilin-2 in human placenta and in situ hybridisation further showed that latrophilin-2 is predominantly expressed in the cytotrophoblast and syncytiotrophoblast. Moreover, latrophilin-2 expression is visible in adherent cells with a remarkably strong signal in microvascular endothelial cells (MVEC) and in human umbilical vein endothelial cells (HUVEC). Deglycosylation experiments using glycosidase F demonstrated that the N-terminal fragment of human latrophilin-2 is highly glycosylated. Using specific antibodies and latrophilin-2 stable cell lines we could show that human latrophilin-2 is cleaved into a 135 kDa N-terminal and a 70 kDa C-terminal fragment. It was also possible to detect the N-terminal fragment of latrophilin-2 in cell culture supernatant of HUVEC indicating that endogenous latrophilin-2 is expressed on the protein level in human vascular endothelial cells and that post-translational modification and generation of a 135 kDa N-terminal fragment takes place. The role of this fragment in the activation of the transmembrane domain of latrophilin-2 or in other cellular processes remains to be elucidated.

Syncytin-A and syncytin-B, two fusogenic placenta-specific murine envelope genes of retroviral origin conserved in Muridae.

Recently, we and others have identified two human endogenous retroviruses that entered the primate lineage 25-40 million years ago and that encode highly fusogenic retroviral envelope proteins (syncytin-1 and -2), possibly involved in the formation of the placenta syncytiotrophoblast layer generated by trophoblast cell fusion at the materno-fetal interface. A systematic in silico search throughout mouse genome databases presently identifies two fully coding envelope genes, present as unique copies and unrelated to any known murine endogenous retrovirus, that we named syncytin-A and -B. Quantitative RT-PCR demonstrates placenta-specific expression for both genes, with increasing transcript levels in this organ from 9.5 to 14.5 days postcoitum. In situ hybridization of placenta cryosections further localizes these transcripts in the syncytiotrophoblast-containing labyrinthine zona. Consistently, we show that both genes can trigger cell-cell fusion in ex vivo transfection assays, with distinct cell type specificities suggesting different receptor usage. Genes orthologous to syncytin-A and -B and disclosing a striking conservation of their coding status are found in all Muridae tested (mouse, rat, gerbil, vole, and hamster), dating their entry into the rodent lineage approximately 20 million years ago. Together, these data strongly argue for a critical role of syncytin-A and -B in murine syncytiotrophoblast formation, thus unraveling a rather unique situation where two pairs of endogenous retroviruses, independently acquired by the primate and rodent lineages, would have been positively selected for a convergent physiological role.