Involvement of nephrin in human placental trophoblast syncytialization

The placenta has numerous functions, such as transporting oxygen and nutrients and building the immune tolerance of the fetus. Cell fusion is an essential process for placental development and maturation. In human placental development, mononucleated cytotrophoblast (CTB) cells can fuse to form a multinucleated syncytiotrophoblast (STB), which is the outermost layer of the placenta. Nephrin is a transmembrane protein that belongs to the Ig superfamily. Previous studies have shown that nephrin contributes to the fusion of myoblasts into myotubes in zebrafish and mice, presenting a functional conservation with its Drosophila ortholog sticks and stones. However, whether nephrin is involved in trophoblast syncytialization remains unclear. In this study, we report that nephrin was localized predominantly in the CTB cells and STB of human placenta villi from first trimester to term pregnancy. Using a spontaneous fusion model of primary CTB cells, the expression of nephrin was found to be increased during trophoblast cell fusion. Moreover, the spontaneous syncytialization and the expression of syncytin 2, connexin 43, and human chorionic gonadotropin beta were significantly inhibited by nephrin-specific siRNAs. The above results demonstrate that nephrin plays an important role in trophoblast syncytialization.

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Involvement of connexin 43 in human trophoblast cell fusion and differentiation

Journal of Cell Science ◽

10.1242/jcs.00648 ◽

2003 ◽

Vol 116 (16) ◽

pp. 3413-3421 ◽

Cited By ~ 93

Author(s):

J.-L. Frendo

Keyword(s):

Cell Fusion ◽

Connexin 43 ◽

Trophoblast Cell ◽

Human Trophoblast

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Tubulin detyrosination promotes human trophoblast syncytium formation

Journal of Molecular Cell Biology ◽

10.1093/jmcb/mjz084 ◽

2019 ◽

Vol 11 (11) ◽

pp. 967-978 ◽

Cited By ~ 6

Author(s):

Rui Wang ◽

Ruoxuan Yu ◽

Cheng Zhu ◽

Hai-Yan Lin ◽

Xiaoyin Lu ◽

...

Keyword(s):

Connexin 43 ◽

Syncytium Formation ◽

First Trimester ◽

Trophoblast Cells ◽

Placental Development ◽

Human Trophoblast ◽

Junction Protein ◽

Elevated Expression ◽

Surface Localization ◽

Cytotrophoblast Cells

Abstract Human trophoblast syncytialization is one of the most important yet least understood events during placental development. In this study, we found that detyrosinated α-tubulin (detyr-α-tub), which is negatively regulated by tubulin tyrosine ligase (TTL), was elevated during human placental cytotrophoblast fusion. Correspondingly, relatively high expression of TTL protein was observed in first-trimester human placental cytotrophoblast cells, but fusing trophoblast cells exhibited much lower levels of TTL. Notably, fusion of preeclamptic cytotrophoblast cells was compromised but could be partially rescued by knockdown of TTL levels. Mechanistically, chronic downregulation of TTL in trophoblast cells resulted in significantly elevated expression of detyr-α-tub. Restoration of detyr-α-tub thus contributed to the cell surface localization of the fusogenic protein Syncytin-2 and the gap junction protein Connexin 43 (Cx43), which in turn promoted successful fusion between trophoblast cells. Taken together, the results suggest that tubulin detyrosination plays an essential role in human trophoblast fusogenic protein aggregation and syncytialization. Insufficient tubulin detyrosination leads to defects in syncytialization and potentially to the onset of preeclampsia.

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Could the Human Endogenous Retrovirus-Derived Syncytialization Inhibitor, Suppressyn, Limit Heterotypic Cell Fusion Events in the Decidua?

International Journal of Molecular Sciences ◽

10.3390/ijms221910259 ◽

2021 ◽

Vol 22 (19) ◽

pp. 10259

Author(s):

Jun Sugimoto ◽

Sehee Choi ◽

Megan Sheridan ◽

Iemasa Koh ◽

Yoshiki Kudo ◽

...

Keyword(s):

Cell Fusion ◽

Cell Types ◽

Trophoblast Cell ◽

Endogenous Retroviruses ◽

Extravillous Trophoblast ◽

Human Endogenous Retrovirus ◽

Decidual Cell ◽

Placental Development ◽

Adverse Pregnancy ◽

Herv Expression

Proper placental development relies on tightly regulated trophoblast differentiation and interaction with maternal cells. Human endogenous retroviruses (HERVs) play an integral role in modulating cell fusion events in the trophoblast cells of the developing placenta. Syncytin-1 (ERVW-1) and its receptor, solute-linked carrier family A member 5 (SLC1A5/ASCT2), promote fusion of cytotrophoblast (CTB) cells to generate the multi-nucleated syncytiotrophoblast (STB) layer which is in direct contact with maternal blood. Another HERV-derived protein known as Suppressyn (ERVH48-1/SUPYN) is implicated in anti-fusogenic events as it shares the common receptor with ERVW-1. Here, we explore primary tissue and publicly available datasets to determine the distribution of ERVW-1, ERVH48-1 and SLC1A5 expression at the maternal-fetal interface. While SLC1A5 is broadly expressed in placental and decidual cell types, ERVW-1 and ERVH48-1 are confined to trophoblast cell types. ERVH48-1 displays higher expression levels in CTB and extravillous trophoblast, than in STB, while ERVW-1 is generally highest in STB. We have demonstrated through gene targeting studies that suppressyn has the ability to prevent ERVW-1-induced fusion events in co-culture models of trophoblast cell/maternal endometrial cell interactions. These findings suggest that differential HERV expression is vital to control fusion and anti-fusogenic events in the placenta and consequently, any imbalance or dysregulation in HERV expression may contribute to adverse pregnancy outcomes.

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Three types of HLA-G+ extravillous trophoblasts that have distinct immune regulatory properties

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2000484117 ◽

2020 ◽

Vol 117 (27) ◽

pp. 15772-15777 ◽

Cited By ~ 2

Author(s):

Henrieta Papuchova ◽

Sarika Kshirsagar ◽

Lily Xu ◽

Hannah A. Bougleux Gomes ◽

Qin Li ◽

...

Keyword(s):

Pregnancy Complications ◽

Inflammatory Responses ◽

Expression Profiles ◽

Gene Expression Profiles ◽

First Trimester ◽

Term Pregnancy ◽

Placental Development ◽

Underlying Mechanisms ◽

And Function ◽

Extravillous Trophoblasts

During pregnancy, invading HLA-G+ extravillous trophoblasts (EVT) play a key role in placental development, uterine spiral artery remodeling, and prevention of detrimental maternal immune responses to placental and fetal antigens. Failures of these processes are suggested to play a role in the development of pregnancy complications, but very little is known about the underlying mechanisms. Here we present validated methods to purify and culture primary HLA-G+ EVT from the placental disk and chorionic membrane from healthy term pregnancy. Characterization of HLA-G+ EVT from term pregnancy compared to first trimester revealed their unique phenotypes, gene expression profiles, and differing capacities to increase regulatory T cells (Treg) during coculture assays, features that cannot be captured by using surrogate cell lines or animal models. Furthermore, clinical variables including gestational age and fetal sex significantly influenced EVT biology and function. These methods and approaches form a solid basis for further investigation of the role of HLA-G+ EVT in the development of detrimental placental inflammatory responses associated with pregnancy complications, including spontaneous preterm delivery and preeclampsia.

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Where Polarity Meets Fusion: Role of Par6 in Trophoblast Differentiation during Placental Development and Preeclampsia

Endocrinology ◽

10.1210/en.2012-1823 ◽

2013 ◽

Vol 154 (3) ◽

pp. 1296-1309 ◽

Cited By ~ 12

Author(s):

Tharini Sivasubramaniyam ◽

Julia Garcia ◽

Andrea Tagliaferro ◽

Megan Melland-Smith ◽

Sarah Chauvin ◽

...

Keyword(s):

Tight Junction ◽

Cell Polarity ◽

Cell Fusion ◽

Trophoblast Cell ◽

Placental Development ◽

Trophoblast Differentiation ◽

Cytoskeleton Dynamics ◽

Insight Into ◽

Cells Cultured

Abstract Trophoblast cell fusion is a prerequisite for proper human placental development. Herein we examined the contribution of Par6 (Partitioning defective protein 6), a key regulator of cell polarity, to trophoblast cell fusion in human placental development. During early placentation, Par6 localized to nuclei of cytotrophoblast cells but with advancing gestation Par6 shifted its localization to the cytoplasm and apical brush border of the syncytium. Exposure of primary isolated trophoblasts to 3% O2 resulted in elevated Par6 expression, maintenance of tight junction marker ZO-1 at cell boundaries, and decreased fusogenic syncytin 1 expression compared with cells cultured at 20% O2. Treatment of choriocarcinoma BeWo cells with forskolin, a known inducer of fusion, increased syncytin 1 expression but decreased that of Par6 and ZO-1. Par6 overexpression in the presence of forskolin maintained ZO-1 at cell boundaries while decreasing syncytin 1 levels. In contrast, silencing of Par6 disrupted ZO-1 localization at cell boundaries and altered the expression and distribution of acetylated α-tubulin. Par6 expression was elevated in preeclamptic placentas relative to normotensive preterm controls and Par6 located to trophoblast cells expressing ZO-1. Together, our data indicate that Par6 negatively regulates trophoblast fusion via its roles on tight junctions and cytoskeleton dynamics and provide novel insight into the contribution of this polarity marker in altered trophoblast cell fusion typical of preeclampsia.

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108. FUNCTIONAL ROLE OF HtrA3 IN TROPHOBLAST CELL INVASION DURING HUMAN PLACENTAL DEVELOPMENT

Reproduction Fertility and Development ◽

10.1071/srb09abs108 ◽

2009 ◽

Vol 21 (9) ◽

pp. 27

Author(s):

H. Singh ◽

G. Nie

Keyword(s):

Cell Invasion ◽

Stromal Cells ◽

Functional Role ◽

First Trimester ◽

Trophoblast Cell ◽

Extravillous Trophoblast ◽

Placental Development ◽

Decidual Cells

Controlled invasion of extravillous trophoblast (EVT) through the maternal decidua is important for placental development and function. Serine protease HtrA3 is highly expressed in the decidual cells in the late secretory phase of the menstrual cycle and throughout pregnancy. It is highly expressed in first trimester in most trophoblast cell types, but not in the invading interstitial trophoblast. HtrA3 and its family members are down-regulated in a number of cancers and are proposed as tumor-suppressors. We hypothesized that HtrA3 is an inhibitor of trophoblast invasion and is down-regulated in invading EVTs, while up-regulation of decidual HtrA3 controls the process. The current study investigated HtrA3 expression in human endometrial stromal cells (HESC) during decidualization in vitro and whether HtrA3 inhibits EVT cell invasion. Stromal cells isolated from human endometrium were decidualized in vitro with estrogen, progesterone and cAMP. Quantitative RT-PCR and western showed HtrA3 mRNA and protein expression was significantly increased in decidualized HESC compared to controls. Indirect immunofluorescence showed homogeneous pattern and increase in intensity of HtrA3 staining in decidualized HESC compared to non-decidualized cells. HTR-8 cells derived from first trimester of pregnancy EVT showed higher levels of HtrA3 mRNA expression compared to other human choriocarcinoma cell lines (AC-1M88, AC-1M32, JEG-3 and BeWo). Both intracellular and extracellular HtrA3 staining was observed in HTR8 cells. Functional role of HtrA3 in cell invasion was determined in HTR-8 cells using an in vitro invasion assay. Exogenous addition of mutant HtrA3 (inhibitor) resulted in a significant increase in HTR-8 cells invading through matrigel coated membrane compared with controls. TGFβ-1 (as positive control) completely inhibited invasion of HTR-8 cells. HtrA3 is tightly regulated during decidualization of HESC in vitro. Inhibition of HtrA3 activity in trophoblastic HTR-8 cells increased invasiveness supporting its functional role during placental development.

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Faculty Opinions recommendation of Intrauterine growth restriction, human placental development and trophoblast cell death.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.3943956.3696054 ◽

2010 ◽

Author(s):

Jeff Dicke

Keyword(s):

Cell Death ◽

Intrauterine Growth Restriction ◽

Trophoblast Cell ◽

Growth Restriction ◽

Placental Development ◽

Intrauterine Growth

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Expression of interleukin-6 (IL-6), signal transducer and activator of transcription-3 (STAT-3) and telomerase in choriocarcinomas

Surgical and Experimental Pathology ◽

10.1186/s42047-020-00080-1 ◽

2020 ◽

Vol 3 (1) ◽

Author(s):

Luciana Pietro ◽

Fátima Bottcher-Luiz ◽

Lício Augusto Velloso ◽

Joseane Morari ◽

Marcelo Nomura ◽

...

Keyword(s):

Cell Transformation ◽

First Trimester ◽

Bewo Cell ◽

Placental Development ◽

Trimester Abortion ◽

Bewo Cells ◽

Culture Cells ◽

Bewo Cell Line ◽

Blastocyst Implantation ◽

First Trimester Of Pregnancy

Abstract Blastocyst implantation and neoplastic invasion have some common properties related to tissue invasion, mediated by various cytokines. Aim To compare the expression of IL-6, STAT-3 and telomerase in material of abortions in the first trimester of pregnancy, at term placentas and in choriocarcinomas. Methods Immunohistochemical reactions were performed on formalin fixed and included in paraffin samples from 3 groups: abortions, normal at term placentas and choriocarcinomas. Western Blot and Real-Time PCR assays were performed on fresh material from BeWo cell line and in primary culture cells of normal placenta. Results Immunohistochemical reactions: IL-6 expression was moderate in the first trimester abortion samples and high in at term placentas and choriocarcinomas. STAT-3 was strongly positive in all groups. Telomerase expression was absent in normal at term placentas but was increased in BeWo cells. Conclusion IL-6 and STAT-3 are present in the invasion process of the normal placental development and they are maintained during the malignant transformation to choriocarcinoma. The intense telomerase expression observed in BeWo cells was strongly associated with the malignant phenotype, confirming it as a good marker for cell transformation and tumor progression.

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