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At least 721 records · Page 40Linked to original sources
PubMed1999

The expression of human leukocyte antigen-G on trophoblasts abolishes the growth-suppressing effect of interleukin-2 towards them.

PROBLEM: We have shown the attenuated human leukocyte antigen (HLA)-G expression on trophoblasts and an aberrant expression of interleukin (IL)-2, a cytotoxic cytokine, in decidual tissue in preeclampsia, where deteriorated trophoblastic invasion into decidual layers may constitute a crucial pathogenesis. We hypothesized that the absence of HLA-G might make trophoblasts susceptible to compromise by IL-2. METHOD OF STUDY: We analyzed the growth of HLA-G-negative and positive cell lines, all of which possessed IL-2 receptors, in the culture with or without IL-2 supplementation. RESULTS: The proliferation of HLA-G positive trophoblastic cell lines (BeWo and JEG-3) was not influenced by the addition of IL-2, whereas a HLA-G-negative trophoblastic cell line (JAR) exhibited significantly decreased proliferation when cultured with IL-2. Interestingly, the transfection of JAR cells with HLA-G completely eliminates the growth-inhibitory effect of IL-2. CONCLUSION: The expression of HLA-G may commit trophoblasts to evade cell damage by IL-2, which may be relevant to maternal tolerance of the fetus during pregnancy and its derangement as exemplified by preeclampsia.

Cell Division↗
PubMed1994

Human trophoblast invasion. Autocrine control and paracrine modulation.

Development of the human placenta involves rapid invasion of the uterine wall by fetal trophoblasts, a process with certain similarities to tumor cell invasion. Unlike tumor invasion, however, this unique interaction between genetically dissimilar trophoblast and uterine cells is closely regulated and limited both temporally and spatially by mechanisms that are largely unknown. We have used a combination of two experimental approaches to study this process: immunolocalization using tissue sections to investigate trophoblast invasion in vivo, and a cell culture model that allows manipulation of the invasion process in vitro. The results show that invading trophoblasts express activated forms of metalloproteinases, adhesion molecules and the novel class I histocompatibility antigen, HLA-G, in a highly regulated manner during invasion. The behavior of cytotrophoblasts in vitro, removed from the influences of uterine cells, closely parallels their behavior in vivo, suggesting the existence of autocrine control mechanisms. However, studies examining the effect of growth factors and cytokines on trophoblast invasion suggest that molecules of uterine origin can modify this process. Thus, we hypothesize that the intrinsic invasiveness of these cells is controlled, at least in part, by the specialized environment of the uterus. Future studies will concentrate on identifying these factors and the specific trophoblast functions they modify.

Animals↗
PubMed1997

Hypoxia stimulates ecNOS mRNA expression by differentiated human trophoblasts.

Cytotrophoblasts isolated from normal human placenta cultured under normoxic conditions (20% O2, pO2 = 130 mmHg) for 48-72 h differentiate to a form which expresses high levels of hCG and which morphologically resembles syncytiotrophoblast. We had previously shown that hypoxia (0-1% O2, pO2 = 12-14 mmHg) blocks this differentiation process, although trophoblasts exposed to hypoxia for up to 96 h were completely viable. In this article we showed that trophoblast responds to hypoxia by expressing the hypoxia-sensitive DNA binding protein HIF-1. We also showed that in trophoblast cultured under normoxic conditions, expression of endothelial cell nitric oxide synthase (ecNOS) mRNA increases with time, reaching a maximum in 48-72 h. However, in trophoblast maintained under hypoxic conditions for 48 h (after an initial 24 h in normoxia), expression of ecNOS mRNA is greatly reduced. These observations are consistent with the expression of ecNOS by syncytiotrophoblast but not by cytotrophoblast. In contrast, exposure of differentiated trophoblasts to hypoxia for 24 h (after 48-72 h in normoxia) significantly stimulates expression of ecNoS mRNA over that of cells maintained continuously in normoxia. These results suggest that in differentiated trophoblast hypoxia can stimulate ecNOS expression.

Cell Differentiation↗
PubMed2001

Differential expression and regulation of inducible nitric oxide synthase (iNOS) mRNA in human trophoblasts in vitro.

OBJECTIVES: To determine the expression of inducible nitric oxide synthase (iNOS) in human trophoblast and to examine the possible regulation of iNOS gene by cytokines. MATERIALS AND METHODS: Total RNA was isolated from: 1) homogenized placental tissue; from 2) isolated and purified cytotrophoblast cells; and 3) cytotrophoblast and syncytiotrophoblast cells treated with cytokines in vitro. RNA was reverse transcribed and amplified by polymerase chain reaction, using specific primers for iNOS. Trophoblast cells were treated in vitro by interferon-gamma (IFN-gamma) in a dose of 10 ng/mL, Interleukin 1beta (IL-1beta) (4 ng/mL) and leukemia inhibitory factor (LIF) (1 ng/mL). Trophoblasts were also subjected to immunocytochemistry using iNOS-specific antibody to detect iNOS protein expression in these cells. RESULTS: The expression of iNOS mRNA was found both in placental tissue and isolated cytotrophoblast cells. In culture, the highly differentiated syncytiotrophoblast expressed more mRNA than cytotrophoblast cells. IFN-gamma and LIF, but not IL-1beta, induced iNOS mRNA expression in trophoblast cells in vitro. The effects of these cytokines on iNOS mRNA were only observed in syncytiotrophoblast cells, but not in cytotrophoblast cells. Immunocytochemical staining confirmed the trophoblast cells as a major source of the iNOS synthase production. CONCLUSIONS: 1) Human trophoblast cells are able to express the iNOS mRNA, hence suggesting a role for NO in placental growth and function. 2) LIF and IFN-gamma, but not IL-1beta, induce the iNOS mRNA expression in syncytiotrophoblast cells in vitro, suggesting possible similar regulatory mechanisms in vivo. 3) This study, for the first time, demonstrates the stimulating effect of LIF on iNOS gene expression in human tissue.

Cells, Cultured↗
PubMed2004

Human amniotic fluid glycoproteins expressing sialyl Lewis carbohydrate antigens stimulate progesterone production in human trophoblasts in vitro.

BACKGROUND: Progesterone is thought to mediate immune modulator effects by regulating uterine responsiveness. The aim of the study was to clarify the effect of transferrin and glycodelin A (former name PP14) as sialyl Lewis X-expressing glycoproteins on the release of progesterone by trophoblast cells in vitro. METHODS: Cytotrophoblast cells were prepared from human term placentas by standard dispersion of villous tissue followed by a Percoll gradient centrifugation step. Trophoblasts were incubated with varying concentrations (50-300 microg/ml) of human amniotic fluid- and serum-transferrin as well as with glycodelin A. Culture supernatants were assayed for progesterone, human chorionic gonadotropin (hCG) and cortisol by enzyme immunometric methods. RESULTS: The release of progesterone is increased in amniotic fluid transferrin- and glycodelin A-treated trophoblast cell cultures compared to untreated trophoblast cells. There is no relation between transferrin and the hCG or cortisol production of trophoblast cells. CONCLUSION: The results suggest that sialyl Lewis carbohydrate antigen-expressing amniotic fluid glycoproteins modulate the endocrine function of trophoblasts in culture by upregulating progesterone production.

Amniotic Fluid↗
PubMed2006

Hypoxia represses the differentiation of Rcho-1 rat trophoblast giant cells.

BACKGROUND: A hypoxic environment is known to be essential for early placentation. A low oxygen tension induces hypoxia-inducible factor-1 (HIF-1alpha) which may play an important role as a transcription factor in maintaining the proliferative and undifferentiated phenotype in human trophoblasts. METHODS: We analyzed the effect of a low oxygen tension on the rat trophoblast giant cell differentiation pathway using Rcho-1 cells which were derived from rat choriocarcinomas and consist of trophoblast stem cells. RESULTS: We found that a low oxygen tension suppressed the morphological changes and steroidogenesis during differentiation. The anticipated downregulation of the Id-1 transcription factor, a negative regulator of trophoblast giant cell differentiation, was not observed in the hypoxic environment. On the other hand, deferoxamine, which mimics hypoxia and induces HIF-1alpha, caused downregulation of Id-1 transcription factor and trophoblast giant cell differentiation. CONCLUSION: These results indicate that hypoxia represses rat trophoblast giant cell differentiation via an HIF-1alpha-independent pathway.

Animals↗
PubMed1994

Invasiveness of mouse trophoblastic cells in connective tissue.

Ectoplacental cones from 8-day-old mouse embryos were grafted into the dorsal subcutaneous tissue of host mice. The grafts were collected between the 3rd and 8th days after transfer and processed for morphological analysis by light and electron microscopy. Approximately 60% of the grafts formed hemorrhagic nodules in which only invasive, giant trophoblastic cells developed. These cells shared many morphological features with the trophoblastic cells involved in normal implantation. At the periphery of the nodules, trophoblastic giant cells were frequently seen growing toward the host connective tissue. The association between the trophoblast and fibrilar components of the extracellular matrix was examined. No direct association with collagen fibrils was noted; however, many areas of the surface of invasive cells were in close proximity with microfibrils of the extracellular matrix. Since only the invasive trophoblast cells exhibited such an association, a direct comparison was made with the process of trophoblast migration within the connective tissue.

Animals↗
PubMed1999

Inhibition of TGF-beta 3 restores the invasive capability of extravillous trophoblasts in preeclamptic pregnancies.

Preeclampsia, the major cause of maternal morbidity and mortality in developed countries, is associated with abnormalities of placenta function due to shallow invasion of the maternal decidua by trophoblasts. Data suggest that TGF-beta may play a role in inhibiting trophoblast outgrowth or invasion, or both. We report that placental TGF-beta 3 expression is high in early pregnancy but falls at around 9 weeks' gestation. This pattern is inversely correlated with trophoblast outgrowth and fibronectin synthesis, markers of early trophoblast differentiation toward an invasive phenotype. We demonstrate that TGF-beta 3 is overexpressed in preeclamptic placentae. In contrast to control placentae, explants from preeclamptic pregnancies fail to exhibit spontaneous invasion in vitro. Significantly, antisense-induced inhibition of TGF-beta 3 expression, and inhibition of TGF-beta 3 activity with antibodies, induces the formation of columns of trophoblast cells, which migrate out of the explant into the underlying Matrigel. To our knowledge, this is the first demonstration that the hypoinvasive placental phenotype characteristic of preeclampsia can be essentially normalized in vitro by biochemical manipulation. We speculate that a failure to downregulate expression of TGF-beta 3 at around 9 weeks' gestation results in shallow trophoblast invasion and predisposes the pregnancy to preeclampsia.

Cell Differentiation↗
PubMed2000

Hypoxia-inducible factor-1 mediates the biological effects of oxygen on human trophoblast differentiation through TGFbeta(3)

During early pregnancy, placentation occurs in a relatively hypoxic environment that is essential for appropriate embryonic development. Intervillous blood flow increases around 10 to 12 weeks of gestation and results in exposure of trophoblast cells to increased oxygen tension. Before this time, low oxygen appears to prevent trophoblast differentiation toward an invasive phenotype. Using human villous explants of 5-8 weeks' gestation, we found that low oxygen tension triggered trophoblast proliferation, fibronectin synthesis, alpha(5) integrin expression, and gelatinase A activity. These biochemical markers were barely detectable under oxic conditions. We therefore examined the placental expression of hypoxia-inducible factor-1 (HIF-1), a master regulator of oxygen homeostasis, and determined that expression of HIF-1alpha subunit during the first trimester of gestation parallels that of TGFbeta(3), an inhibitor of extravillous trophoblast differentiation. Expression of both molecules is high in early pregnancy and falls around 9 weeks of gestation, when placental pO(2) levels are believed to increase. Increasing oxygen tension induced a similar decrease in expression in cultured explants. Moreover, antisense inhibition of HIF-1alpha expression in hypoxic explants inhibited expression of TGFbeta(3), arrested cell proliferation, decreased alpha(5) expression and gelatinase A activity, and triggered biochemical markers of an invasive trophoblast phenotype such as alpha(1) integrin and gelatinase B expression. These data suggest that the oxygen-regulated early events of trophoblast differentiation are in part mediated by TGFbeta(3) through HIF-1 transcription factors.

Cell Differentiation↗
PubMed1979

The pregnant Syrian hamster as a model to study intravascular trophoblasts and associated maternal blood vessel changes.

In pregnant Syrian hamsters (Mesocricetus auratus) used as an animal model for studying the migration of fetal trophoblasts and the associated changes in maternal blood vessels, intravascular trophoblasts migrated well beyond the blood vessels of the uterus and into the vessels of the mesometrium. They migrated beyond the decidua of the uterus, into the lumina of maternal uterine and mesometrial arteries, but not into veins. The arterial changes, which were often segmental, resembled those seen in the decidua and consisted of a replacement of normal smooth muscle cells by poorly differentiated stromal cells. Ultrastructurally, the trophoblasts were either above or below maternal endothelial cells. They occurred also as single or multiple layers within the lumina of arteries that lacked an endothelial lining. Apparent penetration of the elastic membrane by the fetal trophoblasts brought them into close apposition to maternal cells in the arterial wall. Histochemical studies showed heightened metabolic activity of the intravascular trophoblasts as suggested by strong histochemical reactions to nonspecific esterase, succinic dehydrogenase and the glycerophosphate dehydrogenase reactions. Thus, these metabolically active fetal trophoblasts actively migrate into the maternal arterial system, resulting in loss of endothelial cells and changes in the wall of the maternal arteries similar to those in the decidua at the uteroplacental junction.

Animals↗
PubMedDate not supplied

Differentiation-dependent expression of the BCL-2 proto-oncogene in the human trophoblast lineage.

OBJECTIVE: We explored the role of the BCL-2 proto-oncogene in the life cycle of trophoblast cells by examining: 1) the patterns of BCL-2 expression in normal placenta at various gestational ages and in specimens of hydatidiform moles and choriocarcinomas, and 2) the effects of cyclic adenosine monophosphate (cAMP) treatment of JEG-3 choriocarcinoma cells, which induces differentiated functions, on BCL-2. METHODS: BCL-2 protein was localized by indirect immunofluorescence and immunoperoxidase staining of tissue sections and cells using monoclonal and polyclonal antibodies. Western and Northern blotting were used to assess BCL-2 and p53 protein and mRNA levels, respectively. JEG-3 cells were transfected with a BCL-2 expression plasmid to establish that BCL-2 protein could be expressed at high levels in this cell type. RESULTS: BCL-2 immunostaining was most prominent in the syncytiotrophoblast of normal placenta. It was found in syncytiotrophoblast of complete and partial hydatidiform moles, whereas cytotrophoblast staining was weak. BCL-2 immunostaining was also barely detectable in choriocarcinoma cells (JEG-3 cells) and a primary choriocarcinoma. However, BCL-2 protein could be transiently overexpressed in JEG-3 cells by transfection with an expression plasmid. Western blot analysis revealed low levels of BCL-2 in JEG-3 cells and a rise in BCL-2 protein in placental extracts from 10 weeks' gestation to term. In contrast, p53 protein was abundant in JEG-3 cells and normal placenta at 10 weeks' gestation, but low at term, BCL-2 transcripts were substantially more abundant in term placenta than in JEG-3 cells. Treatment of JEG-3 cells with 8-Br-cAMP, which induces genes characteristic of the syncytiotrophoblast, raised BCL-2 protein approximately twofold, whereas p53 mRNA declined. CONCLUSIONS: We conclude that: 1) There is a differentiation-dependent pattern of BCL-2 expression in the placenta, with the protein being most abundant in terminally differentiated trophoblast cells; 2) there appears to be an inverse relation between BCL-2 and p53 expression in trophoblast; and 3) cAMP regulates BCL-2 protein in trophoblast cells. We speculate that the expression of BCL-2 in terminally differentiated trophoblast cells, and hence resistance to apoptotic cell death, may be one mechanism by which trophoblast mass is preserved during pregnancy. Conversely, the relatively low expression of BCL-2 in choriocarcinoma cells may render them more susceptible to apoptosis.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1993

Differentiation and proliferation patterns in human trophoblast revealed by c-erbB-2 oncogene product and EGF-R.

It is well known that growth factors and proto-oncogenes play a pivotal role in organogenesis as well as in tumor development. The human placenta is a rapidly growing organ which shares some aspects with malignant tumors. We have studied the expression of epidermal growth factor receptor (EGF-R) and the receptor encoded by the c-erbB-2 proto-oncogene in first- and third-trimester human placentas. We compared these expression patterns with that of the proliferation marker Ki-67. By immunohistochemistry, EGF-R was intensively expressed in the villous cytotrophoblast in the first trimester. The apical plasma membrane of the syncytium was weakly stained. In placental villi from the third trimester the reaction product for EGF-R was most intense in single villous cytotrophoblastic cells and along the apical plasma membrane of the syncytium, whereas the basal plasma membrane was much less stained. C-erbB-2 protein product was expressed in the first and third trimesters along the apical membrane of the syncytiotrophoblast. Concerning the extravillous trophoblast in cell islands and cell columns, EGF-R was expressed in the cells proximal to the villous stroma whereas the distal cells were c-erbB-2 positive. The Ki-67 antibody revealed the proliferative character of the villous cytotrophoblast and of the EGF-R-positive extravillous trophoblast. In contrast, most of the c-erbB-2-positive cells were Ki-67 negative. By in situ hybridization, c-erbB-2 transcripts were found in all types of villous and extravillous trophoblast, including those that did not express c-erbB-2 protein product. Our data indicate that EGF-R expression is strongly related to the proliferative trophoblast and, with advancing pregnancy, to the differentiated villous trophoblast.off contrast, expression of c-erB-2 protein product occurs only in more advanced stages of trophoblast differentiation, although transcripts of c-erbB-2 are found in both proliferative and differentiated trophoblast. In addition, the coexpression of EGF-R and c-erbB-2 protein product in the syncytiotrophoblast suggests their involvement in complex regulation of hormones and growth factors.

Cell Division↗
PubMed2003

Nitric oxide synthase activity in human trophoblast, term placenta and pregnant myometrium.

To investigate the possible role of nitric oxide (NO) produced locally or intramurally in the quiescence of the pregnant myometrium, nitric oxide synthase (NOS) activity was measured in samples from first trimester (villous, and non villous-trophoblast), term placenta and pregnant myometrium. Trophoblast tissue was obtained from psychosocial termination of pregnancy (9-12 weeks' gestation) whereas placenta and myometrium, from the same patient, at deliveries by Caesarean section. NOS activity was measured in both cytosolic and particulate fractions by the formation of 14C-citrulline from 14C-arginine. Western immunoblotting was used to identify the endothelial NOS (eNOS) and neuronal (nNOS) isoforms. The activity of NOS in particulate fractions from all preparations was considerably higher than the cytosolic fractions. Activity in all fractions except the myometrium was highly Ca-dependent. More than 50% of particulate NOS from the myometrium was Ca-independent. NOS activity was highest in the villous trophoblast and there was a significant difference between the villous and non-villous trophoblast. In placenta and myometrium, NOS was 2-4 fold and 20-28-fold lower than the villous trophoblast, respectively. Western blot analysis showed clearly eNOS in the particulate fraction and a weak eNOS band in the cytosolic fractions, whereas nNOS was not detectable in any of the fractions. In view of the marginal activity of NOS in the myometrium, NO produced by the trophoblast and placenta could play a significant role in maintaining uterine quiescence by paracrine effect.

Adult↗
PubMed2001

Thromboxane A(2) limits differentiation and enhances apoptosis of cultured human trophoblasts.

Prostanoids influence differentiation in diverse cell types. Altered expression of cyclooxygenase and prostaglandins has been implicated in the pathophysiology of placental dysfunction, which results in preeclampsia and fetal growth restriction. We hypothesized that prostanoids modulate differentiation and apoptosis in cultured human trophoblasts. Villous cytotrophoblasts were isolated from term human placentas and cultured in serum-free medium. The level of human chorionic gonadotropin was used as a marker of biochemical differentiation of primary trophoblasts, and syncytia formation was used as a marker of morphologic differentiation. Of the prostanoids tested, we found exposure to thromboxane A(2) hindered both biochemical and morphologic differentiation of cultured trophoblasts. As expected, human chorionic gonadotropin levels in the media were elevated in a concentration-dependent manner in the presence of the thromboxane synthase inhibitor, sodium furegrelate, or the thromboxane A(2) receptor blocker SQ 29,548. Furthermore, thromboxane A(2) enhanced trophoblast apoptosis, determined using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, cell morphology, and a concentration-dependent increase in p53 expression. We conclude that thromboxane A(2) hinders differentiation and enhances apoptosis in cultured trophoblasts from term human placenta. We speculate that thromboxane may contribute to placental dysfunction by restricting differentiation and enhancing apoptosis in human trophoblasts.

Apoptosis↗
PubMed2004

Hypoxia-inducible factor-1 transactivates transforming growth factor-beta3 in trophoblast.

Hypoxia occurs during the development of placenta in the first trimester and is implicated in trophoblast differentiation. Intervillous blood flow increases after 10 wk of gestation and results in exposure of trophoblast cells to oxygen. Before this time, low oxygen appears to prevent trophoblast differentiation toward an invasive phenotype. The oxygen-regulated early events of trophoblast differentiation are mediated by TGF-beta3. TGF-beta3 plays a vital role in trophoblast differentiation, and its overexpression can be found in preeclamptic placenta. We sought to determine the mechanism of TGF-beta3 expression through hypoxia-inducible factor (HIF)-1. We show that HIF-1alpha and TGF-beta3 are overexpressed in preeclamptic placenta. Hypoxia not only transactivates the TGF-beta3 promoter activity but also enhances endogenous TGF-beta3 expression. Using the TGF-beta3 promoter deletion mutants, we show that the region between -90 and -60, which contains a putative HIF-1 consensus motif, is crucial for HIF-1-mediated transactivation. Electrophoretic mobility shift assays show that HIF-1 binds to the oligonucleotide containing the HIF-1 motif. Also, introduction of an antisense oligonucleotide for HIF-1 diminishes TGF-beta3 expression during hypoxia, indicating that the up-regulation of TGF-beta3 by hypoxia is mediated through HIF-1. Our results provide evidence that regulation of TGF-beta3 promoter activity by HIF-1 represents a mechanism for trophoblast differentiation during hypoxia.

Cell Line, Tumor↗
PubMed2004

Lipids from oxidized low-density lipoprotein modulate human trophoblast invasion: involvement of nuclear liver X receptors.

Human embryonic implantation involves major invasion of the uterine wall and remodeling of the uterine arteries by extravillous cytotrophoblast cells (EVCT). Abnormalities in these early steps of placental development lead to poor placentation and fetal growth defects and are frequently associated with preeclampsia, a major complication of human pregnancy. We recently showed that oxidized low-density lipoproteins (oxLDLs) are present in situ in EVCT and inhibit cell invasion in a concentration-dependent manner. The aim of the present study was to better understand the mechanisms by which oxLDL modulate trophoblast invasion. We therefore investigated the presence of oxLDL receptors in our cell culture model of human invasive primary EVCT. We found using immunocytochemistry and immunoblotting that the lectin-like oxLDL receptor-1 was the scavenger receptor mainly expressed in EVCT and was probably involved in oxLDL uptake. We next examined the effect of low-density lipoprotein oxidative state on trophoblast invasion in vitro using EVCT cultured on Matrigel-coated Transwell. We demonstrated that only oxLDL containing a high proportion of oxysterols and phosphatidylcholine hydroperoxide derivatives that provide ligands for liver X receptor (LXR) and peroxisomal proliferator-activated receptor gamma (PPARgamma), respectively, reduced trophoblast invasion. We next investigated the presence and the role of these nuclear receptors and found that in addition to PPARgamma, human invasive trophoblasts express LXRbeta, and activation of these nuclear receptors by specific synthetic or natural ligands inhibited trophoblast invasion. Finally, using a PPARgamma antagonist, we suggest that LXRbeta, rather than PPARgamma, is involved in oxLDL-mediated inhibition of human trophoblast invasion in vitro.

Cell Nucleus↗
PubMed1994

Recapitulation of the pathway for trophoblast giant cell differentiation in vitro: stage-specific expression of members of the prolactin gene family.

The trophoblast giant cell lineage is characterized by endoreduplication and expression of members of the PRL gene family. This report describes the functional consequences following in vitro manipulation of a rat trophoblast cell line, termed Rcho-1. Rcho-1 cells can be cultured under conditions that promote proliferation or differentiation. Proliferation is maintained by culturing the cells in the presence of fetal bovine serum under subconfluent conditions. Differentiation is induced by growing the cells to confluence and removing the mitogenic source. Differentiation is characterized by continued synthesis of DNA in the absence of proliferation (endoreduplication) and the sequential expression of members of the PRL gene family. Western and Northern blot analyses demonstrated that placental lactogen-I (PL-I) was first expressed, followed sequentially by PL-II, PRL-like protein-A, and PRL-like protein-C. The ontogeny of expression of members of the PRL gene family by the Rcho-1 cells recapitulated the pattern of in situ expression by trophoblast giant cells of the junctional zone of the chorioallantoic placenta. A notable difference between in vivo trophoblast giant cell differentiation and in vitro Rcho-1 cell differentiation is the termination of PL-I expression in normal trophoblast giant cells developing in vivo and the continued expression of PL-I in differentiated Rcho-1 cell cultures. The Rcho-1 cell line provides a unique in vitro model for investigating the initiation and maintenance of the trophoblast giant cell differentiation pathway.

Animals↗
PubMed1999

Distinct regulatory regions from the prolactin-like protein C variant promoter direct trophoblast giant cell versus spongiotrophoblast cell-specific expression.

PRL-like protein C variant (PLP-Cv) is a newly identified member of the PRL family. PLP-Cv is specifically expressed in the chorioallantoic placenta by two distinct cell populations: trophoblast giant cells and spongiotrophoblast cells. To gain some insight regarding the control of PLP-Cv gene expression and the regulatory factors controlling trophoblast giant cell and spongiotrophoblast cell lineages, we have initiated a structural and functional analysis of the PLP-Cv promoter. The activities of a series of PLP-Cv promoter constructs, ranging in size from 4.5 kb to 50 bp, ligated to a luciferase reporter have been assessed in the Rcho-1 trophoblast cell line (restricted to trophoblast giant cell differentiation) and in a primary spongiotrophoblast cell culture system after transient transfection. PLP-Cv promoter constructs containing 4.5 kb to 149 bp of 5'-flanking DNA possessed full activity in the trophoblast giant cell model. A region located between -149 and -124 bp upstream of the PLP-Cv transcription start site was found to be essential for activation of the PLP-Cv promoter. Spongiotrophoblast cells required additional PLP-Cv 5'-flanking DNA for full activity. A region located between -2518 and -2242 bp upstream of the PLP-Cv transcription start site significantly enhanced PLP-Cv promoter in spongiotrophoblast cells. In conclusion, mechanisms underlying the activation of the PLP-Cv promoter are different in trophoblast giant cells vs. spongiotrophoblast cells.

Animals↗