Gestation stage-dependent intrauterine trophoblast cell invasion in the rat and mouse: novel endocrine phenotype and regulation

Trophoblast cell invasion into the uterine wall is characteristic of hemochorial placentation. In this report, we examine trophoblast cell invasion in the rat and mouse, the endocrine phenotype of invasive trophoblast cells, and aspects of the regulation of trophoblast cell invasion. In the rat, trophoblast cells exhibit extensive interstitial and endovascular invasion. Trophoblast cells penetrate through the decidua and well into the metrial gland, where they form intimate associations with the vasculature. Trophoblast cell invasion in the mouse is primarily interstitial and is restricted to the mesometrial decidua. Both interstitial and endovascular rat trophoblast cells synthesize a unique set of prolactin (PRL)-like hormones/cytokines, PRL-like protein-A (PLP-A), PLP-L, and PLP-M. Invading mouse trophoblast cells also possess endocrine activities, including the expression of PLP-M and PLP-N. The trafficking of natural killer (NK) cells and trophoblast cells within the mesometrial uterus is reciprocal in both the rat and mouse. As NK cells disappear from the mesometrial compartment, a subpopulation of trophoblast cells exit the chorioallantoic placenta and enter the decidua. Furthermore, the onset of interstitial trophoblast cell invasion is accelerated in mice with a genetic deficiency of NK cells, Tg epsilon 26 mice, implicating a possible regulatory role of NK cells in trophoblast cell invasion. Additionally, the NK cell product, interferon-gamma (IFNgamma), inhibits trophoblast cell outgrowth, and trophoblast cell invasion is accelerated in mice with a genetic deficiency in the IFNgamma or the IFNgamma receptor. In summary, trophoblast cells invade the uterine wall during the last week of gestation in the rat and mouse and possess a unique endocrine phenotype, and factors present in the uterine mesometrial compartment modulate their invasive behavior.     

Maternal hypoxia activates endovascular trophoblast cell invasion

Oxygen is a critical regulator of placentation. Early placental development occurs in a predominantly low oxygen environment and is, at least partially, under the control of hypoxia signaling pathways. In the present study, in vivo hypobaric hypoxia was used as an experimental tool to delineate hypoxia-sensitive events during placentation. Pregnant rats were exposed to the equivalent of 11% oxygen between days 6.5 and 13.5 of gestation. Pair-fed pregnant animals exposed to ambient conditions were included as a control group. Uterine mesometrial blood vessels in the hypoxia-exposed animals were greatly expanded and some contained large cuboidal cells that were positive for cytokeratin and other markers characteristic of invasive trophoblast cells. Unlike later in gestation, the route of trophoblast cell invasion in the hypoxia-exposed animals was restricted to endovascular, with no interstitial invasion observed. Hypoxia-activated endovascular trophoblast invasion required exposure to hypoxia from gestation day 8.5 to day 9.5. Activation of the invasive trophoblast lineage was also associated with an enlargement of the junctional zone of the chorioallantoic placenta, a source of invasive trophoblast cell progenitors. In summary, maternal hypoxia during early stages of placentation activates the invasive endovascular trophoblast cell lineage and promotes uterine vascular remodeling.     

FOSL1 is integral to establishing the maternal-fetal interface

Remodeling of uterine spiral arteries by trophoblast cells is a requisite process for hemochorial placentation and successful pregnancy. The rat exhibits deep intrauterine trophoblast invasion and accompanying trophoblast-directed vascular modification. The involvement of phosphatidylinositol 3 kinase (PI3K), AKT, and Fos-like antigen 1 (FOSL1) in regulating invasive trophoblast and hemochorial placentation was investigated using Rcho-1 trophoblast stem cells and rat models. Disruption of PI3K/AKT with small-molecule inhibitors interfered with the differentiation-dependent elaboration of a signature invasive-vascular remodeling trophoblast gene expression profile and trophoblast invasion. AKT isoform-specific knockdown also affected the signature invasive-vascular remodeling trophoblast gene expression profile. Nuclear FOSL1 increased during trophoblast cell differentiation in a PI3K/AKT-dependent manner. Knockdown of FOSL1 disrupted the expression of a subset of genes associated with the invasive-vascular remodeling trophoblast phenotype, including the matrix metallopeptidase 9 gene (Mmp9). FOSL1 was shown to occupy regions of the Mmp9 promoter in trophoblast cells critical for the regulation of Mmp9 gene expression. Inhibition of FOSL1 expression also abrogated trophoblast invasion, as assessed in vitro and following in vivo trophoblast-specific lentivirally delivered FOSL1 short hairpin RNA (shRNA). In summary, FOSL1 is a key downstream effector of the PI3K/AKT signaling pathway responsible for development of trophoblast lineages integral to establishing the maternal-fetal interface.     

Pregnancy in the brown Norway rat: a model for investigating the genetics of placentation

The placenta facilitates the exchange of nutrients and wastes in an effort to promote fetal development. Disruptions in the establishment of the placenta and its interactions with the maternal uterus are potential causes of pregnancy failure. In this study we investigated the pregnancy phenotype of two inbred rat strains: the Dahl Salt Sensitive (DSS) strain and the Brown Norway (BN) strain. The DSS strain is reported to have large litters, whereas the BN strain has small litters. Pregnant female rats of each strain were killed on various days of gestation. At the time of killing, the number of viable versus dead and/or resorbing conceptuses was determined. Placental tissues from viable conceptuses were collected and processed for biochemical and histologic analyses. The number of viable conceptuses at Days 8.5 and 18.5 of gestation was significantly greater in DSS versus BN rats. Additionally, the number of resorbing and/or dying conceptuses was significantly greater in the BN strain than in the DSS strain. Maternal responses to pregnancy and elements of placental and fetal development in DSS and BN rats differed. Immunohistologic analysis of placentation and gene expression profiles revealed that trophoblast cell invasion into the uterine mesometrial compartment was significantly less in the BN strain versus the DSS strain. In contrast, the uterine natural killer cell population was reciprocally expanded in the BN strain. The impairment in trophoblast cell invasion in BN rats was associated with a smaller junctional zone compartment of the chorioallantoic placenta. Collectively, the data indicate that BN rats exhibit a unique form of placentation and may represent an excellent model for investigating the genetics of placental development.     

The rat as an animal model for fetoplacental development: a reappraisal of the post-implantation period

Following implantation in rodents, the uterine stromal fibroblasts differentiate into densely packed decidual cells. This process, called decidualization, is well-orchestrated and progresses both antimesometrially and mesometrially, creating two regions with distinctive cellular morphologies. In addition, subsequent placental development is dependent on the invasion of the trophoblast, the process intimately linked to the endometrial tissue remodelling and depending largely on the environment created by the decidua; this phenomenon is crucial for the establishment and maintenance of pregnancy. The key mechanisms underlying the maternal tissue remodelling and trophoblast invasion remain poorly understood. The rat, just like human beings, exhibits a highly invasive type of placental development, the haemochorial placentation. For obvious ethical reasons, the studies of endometrial tissue remodelling throughout pregnancy in humans are greatly limited. Although the rat differs somewhat from humans with regards to the implantation process, it is an appropriate model for studying the mechanisms of decidualization as well as subsequent remodelling of the uterine tissues and fetoplacental development. As decidual remodelling is very closely linked to placentation and the maternal-fetal interactions in the rat show several important similarities to human placentation, the morphological alterations occurring during the post-implantation period in the rat have been addressed in the present review.     

Extracellular matrix remodelling in rat endometrium during early pregnancy: The role of fibronectin and laminin

The endometrial extracellular matrix (ECM) remodelling has a crucial role in the establishment of a successful pregnancy. In addition to its basic function such as regulation of cell function, differentiation, migration, proliferation, the substantial alterations in the endometrial ECM may play a specific role in the trophoblast invasion, placentation, cell death and formation of the proper and functional implantation chamber around the embryo. In the present study, immunolocalizations of fibronectin and laminin were determined using avidin-biotin complex-peroxidase in rat implantation sites during 7-10 days of pregnancy. Both proteins were present in the basal membrane of blood vessels and in decidual matrix whereas they were absent or had very weak reactivity in the primary decidual zone on day 7. When placentation has begun, the immunoreactivity of both proteins was increased in the placental bed and in the basal membrane of blood vessels of the mesometrial region. The immunolocalization of both proteins seemed to be decreased in the antimesometrial decidua, however, it was increased in the mesometrial decidual matrix on days 9 and 10. Therefore, it could be suggested laminin and fibronectin demonstrating dynamic expressions in relation with the morphological differentiation of endometrial stroma may play crucial roles in the control of trophoblast adhesion and invasion, in placentation and angiogenesis, in the determination of cell shape and fate thus contributing the endometrial receptivity and a successful pregnancy.     

Utility of human placental alkaline phosphatase as a genetic marker for cell tracking in bone and cartilage

It was the aim of the current study to evaluate the utility of human placental alkaline phosphatase (hPLAP) as a genetic marker for cell tracking in bone and cartilage, using transgenic Fischer 344 rats expressing hPLAP under the control of the ubiquitous R26 promoter [F344-Tg(R26-hPLAP)]. hPLAP enzyme activity was retained during paraffin and methylmethacrylate (MMA) embedding, and was best preserved using 40% ethanol as fixative. Endogenous alkaline phosphatase activity could be completely blocked by heat inactivation in paraffin and MMA sections, allowing histochemical detection of hPLAP in the complete absence of background staining. In addition, sensitive detection of hPLAP was also possible using immunohistochemistry. F344-Tg(R26-hPLAP) rats demonstrated ubiquitous expression of hPLAP in hematopoietic bone marrow cells and stromal cells such as osteoblasts, osteocytes, and chondrocytes. Osteoclasts only weakly expressed hPLAP. In conclusion, hPLAP provides superb detection quality in paraffin and plastic sections, and constitutes an excellent genetic marker for cell tracking in hard and soft tissues.     

Marker tolerant,immunocompetent animals as a new tool for regenerative medicine and long-term cell tracking

Background  

Immune-mediated rejection of labeled cells is a general problem in transplantation studies using cells labeled with any immunogenic marker, and also in gene therapy protocols. The aim of this study was to establish a syngeneic model for long-term histological cell tracking in the absence of immune-mediated rejection of labeled cells in immunocompetent animals. We used inbred transgenic Fischer 344 rats expressing human placental alkaline phosphatase (hPLAP) under the control of the ubiquitous R26 promoter for this study. hPLAP is an excellent marker enzyme, providing superb histological detection quality in paraffin and plastic sections.     

Non‐invasive placentation in the marsupials Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae) involves redistribution of uterine Desmoglein‐2

In mammalian pregnancy, the uterus is remodeled to become receptive to embryonic implantation. Since non‐invasive placentation in marsupials is likely derived from invasive placentation, and is underpinned by intra‐uterine conflict between mother and embryo, species with non‐invasive placentation may employ a variety of molecular mechanisms to maintain an intact uterine epithelium and to prevent embryonic invasion. Identifying such modifications to the uterine epithelium of marsupial species with non‐invasive placentation is key to understanding how conflict is mediated during pregnancy in different mammalian groups. Desmoglein‐2, involved in maintaining lateral cell–cell adhesion of the uterine epithelium, is redistributed before implantation to facilitate embryo invasion in mammals with invasive placentation. We identified localization patterns of this cell adhesion molecule throughout pregnancy in two marsupial species with non‐invasive placentation, the tammar wallaby (Macropus eugenii; Macropodidae), and the brushtail possum (Trichosurus vulpecula; Phalangeridae). Interestingly, Desmoglein‐2 redistribution also occurs in both M. eugenii and T. vulpecula, suggesting that cell adhesion, and thus integrity of the uterine epithelium, is reduced during implantation regardless of placental type, and may be an important component of uterine remodeling. Desmoglein‐2 also localizes to the mesenchymal stromal cells of M. eugenii and to epithelial cell nuclei in T. vulpecula, suggesting its involvement in cellular processes that are independent of adhesion and may compensate for reduced lateral adhesion in the uterine epithelium. We conclude that non‐invasive placentation in marsupials involves diverse and complementary strategies to maintain an intact epithelial barrier.     

Elevated expression of N-acetylglucosaminyltransferase V in first trimester human placenta

In early pregnancy, placental trophoblast cells rapidly grow and invade into maternal uterine tissue. N-Acetylglucosaminyltransferase V (GnT-V) and its product, beta1-6-GlcNAc branching glycan, are known to correlate with tumor invasion and metastasis. Since the placentation process resembles invasion of cancer cells, we examined the expression of beta1-6-GlcNAc branching glycan and GnT-V in human placenta. Placentas derived from the first trimester contained a larger amount of beta1-6-GlcNAc branching glycan, detected by leukoagglutinating phytohemagglutinin lectin blotting, than those at term. Immunohistochemical study revealed that beta1-6-GlcNAc branching glycans and GnT-V protein were localized in the trophoblast layer. Both protein expression and the enzyme activity of GnT-V in first trimester placentas were higher than those at term. These results suggest that GnT-V would contribute to placentation in the early phase of pregnancy, possibly regulating the process of invasion of trophoblast cells.     

Uterine leukocytes: key players in pregnancy

In species with hemochorial placentation, which includes humans, mice and rats, antigen-specific T and B lymphocytes which are responsible for acquired immunity are virtually absent from the maternal-fetal interface. In contrast, non-antigen specific natural killer cells and macrophages which provide innate immunity are abundant and highly specialized. Autocrine/paracrine factors such as steroid and polypeptide hormones, prostaglandins and anti-inflammatory cytokines that are present in the uterine environment during pregnancy re-program their secretory profiles. Recent studies using transgenic mice and other approaches indicate that these environmentally modified leukocytes have major pregnancy-associated functions that include facilitation of implantation, modulation of the maternal uterine vasculature, supply of growth factors to the placenta, promotion of trophoblast differentiation and facilitation of parturition.     

Placental villous mesenchymal cells trigger trophoblast invasion

The successful transformation of uterine spiral arteries by invasion trophoblasts is critical for the formation of the human hemochorial placenta. Placental trophoblast migration and invasion are well regulated by various autocrine/paracrine factors at maternal–fetal interface. Human placental multipotent mesenchymal stromal cells (hPMSCs) are a subpopulation of villous mesenchymal cells and have been shown to produce a wide array of soluble cytokines and growth factors including HGF (hepatocyte growth factor). The function of hPMSCs in placental villous microenvironment has not been explored. The interaction between hPMSCs and trophoblasts was proposed in vitro in a recent article. HGF produced by hPMSCs was able to engage c-Met receptor on trophoblast and induced the trophoblast cAMP expression. The cAMP activated PKA, which in turn, signaled to Rap1 and led to integrin β1 activation. The total integrin β1 protein expression by trophoblasts was not affected by HGF stimulation. Hypoxia downregulated HGF expression by hPMSCs. HGF and PKA activator 6-Bnz-cAMP increased trophoblast adhesion and migration that were inhibited by PKA inhibitor H89 or Rap1 siRNA. Thus, hPMSCs-derived paracrine HGF can regulate trophoblast migration during placentation. These findings provided insight revealing at least one mechanism by which hPMSCs implicated in the development of preeclampsia.     

Control of human trophoblast function

The trophoblast, i.e. the peripheral part of the human conceptus, exerts a crucial role in implantation and placentation. Both processes properly occur as a consequence of an intimate dialogue between fetal and maternal tissues, fulfilled by membrane ligands and receptors, as well as by hormone and local factor release. During blastocyst implantation, generation of distinct trophoblast cell types begins, namely the villous and the extravillous trophoblast, the former of which is devoted to fetal-maternal exchanges and the latter binds the placental body to the uterine wall. Physiological placentation is characterized by the invasion of the uterine spiral arteries by extravillous trophoblast cells arising from anchoring villi. Due to this invasion, the arterial structure is replaced by amorphous fibrinoid material and endovascular trophoblastic cells. This transformation establishes a low-resistance, high-capacity perfusion system from the radial arteries to the intervillous space, in which the villous tree is embedded. The physiology of pregnancy depends upon the orderly progress of structural and functional changes of villous and extravillous trophoblast, whereas a derangement of such processes can lead to different types of complications of varying degrees of gravity, including possible pregnancy loss and maternal life-threatening diseases. In this review we describe the mechanisms which regulate trophoblast differentiation, proliferation, migration and invasiveness, and the alterations in these mechanisms which lead to pathological conditions. Furthermore, based on the growing evidence that proper inflammatory changes and oxidative balance are needed for successful gestation, we explain the mechanisms by which agents able to influence such processes may be useful in the prevention and treatment of pregnancy disorders.     

Placental villous mesenchymal cells trigger trophoblast invasion

The successful transformation of uterine spiral arteries by invasion trophoblasts is critical for the formation of the human hemochorial placenta. Placental trophoblast migration and invasion are well regulated by various autocrine/paracrine factors at maternal–fetal interface. Human placental multipotent mesenchymal stromal cells (hPMSCs) are a subpopulation of villous mesenchymal cells and have been shown to produce a wide array of soluble cytokines and growth factors including HGF (hepatocyte growth factor). The function of hPMSCs in placental villous microenvironment has not been explored. The interaction between hPMSCs and trophoblasts was proposed in vitro in a recent article. HGF produced by hPMSCs was able to engage c-Met receptor on trophoblast and induced the trophoblast cAMP expression. The cAMP activated PKA, which in turn, signaled to Rap1 and led to integrin β1 activation. The total integrin β1 protein expression by trophoblasts was not affected by HGF stimulation. Hypoxia downregulated HGF expression by hPMSCs. HGF and PKA activator 6-Bnz-cAMP increased trophoblast adhesion and migration that were inhibited by PKA inhibitor H89 or Rap1 siRNA. Thus, hPMSCs-derived paracrine HGF can regulate trophoblast migration during placentation. These findings provided insight revealing at least one mechanism by which hPMSCs implicated in the development of preeclampsia.     

Intrauterine trophoblast migration: A comparative view of humans and rodents

ABSTRACT

Trophoblast migration and invasion through the decidua and maternal uterine spiral arteries are crucial events in placentation. During this process, invasive trophoblast replace vascular endothelial cells as the uterine arteries are remodeled to form more permissive vessels that facilitate adequate blood flow to the growing fetus. Placentation failures resulting from either extensive or shallow trophoblastic invasion can cause pregnancy complications such as preeclampsia, intrauterine growth restriction, placenta creta, gestational trophoblastic disease and even maternal or fetal death. Consequently, the use of experimental animal models such as rats and mice has led to great progress in recent years with regards to the identification of mechanisms and factors that control trophoblast migration kinetics. This review aims to perform a comparative analysis of placentation and the mechanisms and factors that coordinate intrauterine trophoblast migration in humans, rats and mice under physiological and pathological conditions.     

Nodal signals via β-arrestins and RalGTPases to regulate trophoblast invasion

Placentation is critical for establishing a healthy pregnancy. Trophoblasts mediate implantation and placentation and certain subtypes, most notably extravillous cytotrophoblast, are highly invasive. Trophoblast invasion is tightly regulated by microenvironmental cues that dictate placental morphology and depth. In choriocarcinomas, malignant trophoblast cells become hyperinvasive, breaching the myometrium and leading to major complications. Nodal, a member of the TGF-β superfamily, is expressed throughout the endometrium during the peri-implantation period and in invasive trophoblast cells. Nodal promotes the invasion of numerous types of cancer cells. However, Nodal's role in trophoblast and choriocarcinoma cell invasion is unclear. Here we show that Nodal stimulates the invasion of both the non-malignant HTR-8SV/neo trophoblast and JAR choriocarcinoma cells in a dose-dependent manner. We found that endogenous β-arrestins and Ral GTPases, key regulators of the cell cytoskeleton, are constitutively associated with Nodal receptors (ALK4 and ALK7) in trophoblast cells and that RalA is colocalized with ALK4 in endocytic vesicles. Nodal stimulates endogenous β-arrestin2 to associate with phospho-ERK1/2, and knockdown of β-arrestin or Ral proteins impairs Nodal-induced trophoblast and choriocarcinoma cell invasion. These results demonstrate, for the first time, that β-arrestins and RalGTPases are important regulators of Nodal-induced invasion.     

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.     

Osteopontin expression in uterine stroma indicates a decidualization-like differentiation during ovine pregnancy

Osteopontin (OPN) is a component of the extracellular matrix that interacts with cell surface receptors, including integrins, to mediate cell adhesion, migration, differentiation, survival, and immune function. In pregnant mice and primates, OPN has been detected in decidualized stroma and is considered to be a gene marker for decidualization. Decidualization involves transformation of spindle-like fibroblasts into polygonal epithelial-like cells that are hypothesized to limit conceptus trophoblast invasion through the uterine wall during invasive implantation. Decidualization is not considered characteristic of species with noninvasive implantation, such as domestic animals. However, the extent of trophoblast invasion between sheep and pigs differs, with sheep exhibiting erosion of the uterine luminal epithelium (LE) and fusion of trophectoderm with LE to form syncytia, and pigs maintaining an intact LE throughout pregnancy. Therefore, the present study measured changes in the decidualization marker genes OPN, desmin, and alpha smooth muscle actin (alphaSMA) in ovine and porcine uterine stroma throughout pregnancy. The morphology of endometrial stromal cells in pregnant ewes changes following conceptus attachment, with cells increasing in size and becoming polyhedral in shape by Day 35 of pregnancy. Expression of OPN mRNA and protein, as well as desmin and alphaSMA proteins, was observed in this same uterine stromal compartment. In contrast, no morphological changes in uterine stroma nor induction of OPN mRNA and protein, or desmin protein, were detected during porcine pregnancy. Interestingly, alphaSMA protein was absent on Day 20, but prominent in uterine stroma of pregnant pigs on Day 45. Collectively, these results indicate that the uterine stroma of sheep undergoes a program of differentiation similar to decidualization in invasive implanting species, whereas porcine stroma exhibits differentiation that is more limited than that in sheep, rodents, or primates. Results suggest that uterine stromal decidualization is common to species with different types of placentation, but the extent is variable and correlates with the depth of trophoblast invasion during implantation.     

Protein phosphatase 1A (PPM1A) is involved in human cytotrophoblast cell invasion and migration

Trophoblast invasion is crucial for embryo implantation and placentation. Excessive trophoblast invasion leads to hydatidiform moles and choriocarcinoma. PPM1A is a phosphatase which dephosphorylates and inactivates a broad range of substrates, including TGF-β, MAP kinases, p38 and JNK kinase cascades, and is involved in tumor suppression. The objective of this study was to investigate the expression of PPM1A in normal and malignant human placenta and its role in trophoblast invasion, which shares many similarities with invasion of tumor cells. By Western blotting and immunocytochemistry, significantly higher expression of PPM1A in human placental villi at term was found as compared with that during the first trimester. Furthermore, the expression level of PPM1A protein in hydatidiform moles was lower compared with that during normal pregnancy. We further investigated the function of PPM1A in extravillous trophoblast cell line HTR8/SVneo. Transwell migration and Matrigel invasion assays demonstrated that PPM1A siRNA significantly promoted the motility and invasiveness of the cells. Gelatin zymography showed that knockdown of PPM1A with siRNA elevated the expression of pro-matrix metalloproteinase pro-(MMP)-9, but down-regulated tissue inhibitors of metalloproteinases (TIMP)-2. The present data indicate that PPM1A plays a critical role in the regulation of normal placentation by inhibiting trophoblast migration and invasion.     

Prostasin inhibits cell invasion in human choriocarcinomal JEG-3 cells

Controlled invasion of the uterine wall by the trophoblast cells is pivotal for the successful pregnancy, and various kinds of protease are involved in this process. Serine protease prostasin has been shown to participate in the proteolytic activation of epithelial sodium channel as well as cleavage of epidermal growth factor receptor extracellular domain in human epithelial cells. Its physiological significance in human placentation has been suggested but not validated. In the present study, we found that prostasin was expressed at a relatively high level in human placenta trophoblasts in early pregnant weeks. In the in vitro cultured human choriocarcinomal JEG-3 cells, treatment with functional antibody against prostasin led to promotion in cell invasion capability, as well as increase in the production of MMP-2, MMP-26, TIMP-1, and TIMP-4. Our data indicated that this serine protease may function as an invasion suppressor in human trophoblast, participating in the invasion-restrictive regulation of trophoblasts to avoid their over-penetration into the uterine wall.