β-1,4-Galactosyltransferase III suppresses extravillous trophoblast invasion through modifying β1-integrin glycosylation

Alpha 1,3 N-Acetylgalactosaminyl Transferase (GTA) Impairs Invasion Potential of Trophoblast Cells in Preeclampsia

Preeclampsia (PE) is a pregnancy-specific disorder associated with shallow invasion of the trophoblast cells and insufficient remodeling of the uterine spiral artery. Protein glycosylation plays an important role in trophoblast cell invasion. However, the glycobiological mechanism of PE has not been fully elucidated. In the current study, employing the Lectin array, we found that soybean agglutinin (SBA), which recognizes the terminal N-acetylgalactosamine α1,3-galactose (GalNAc α1,3 Gal) glycotype, was significantly increased in placental trophoblast cells from PE patients compared with third-trimester pregnant controls. Upregulating the expression of the key enzyme α1,3 N-acetylgalactosaminyl transferase (GTA) promoted the biosynthesis of terminal GalNAc α1,3 Gal and inhibited the migration/invasion of HTR8/SVneo trophoblast cells. Moreover, the methylation status of GTA promoter in placental tissues from PE patients was lower than that in the third trimester by methylation-specific PCR (MSP) and bisulfite sequencing PCR (BSP) analysis. Elevated GTA expression in combination with the DNA methylation inhibitor 5-azacytidine (5-AzaC) treatment increased the glycotype biosynthesis and impaired the invasion potential of trophoblast cells, leading to preeclampsia. This study suggests that elevated terminal GalNAc α1,3 Gal biosynthesis and GTA expression may be applied as the new markers for evaluating placental function and the auxiliary diagnosis of preeclampsia.

N-linked α2,6-sialylation of integrin β1 by the sialyltransferase ST6Gal1 promotes cell proliferation and stemness in gestational trophoblastic disease

INTRODUCTION

Gestational trophoblastic disease (GTD) encompasses a spectrum of rare pre-malignant and malignant entities originating from trophoblastic tissue, including partial hydatidiform mole, complete hydatidiform mole and choriocarcinoma. β-galactoside α2,6 sialyltransferase 1 (ST6Gal1), the primary sialyltransferase responsible for the addition of α2,6 sialic acids, is strongly associated with the occurrence and development of several tumor types. However, the role of ST6Gal1/α2,6 -sialylation of trophoblast cells in GTD is still not well understood.

METHODS

The expression of ST6Gal1 was investigated in GTD and human immortalized trophoblastic HTR-8/SVneo cells and human gestational choriocarcinoma JAR cells. We evaluated the effect of ST6Gal1 on proliferation and stemness of trophoblastic cells. We also examined the effect of internal miR-199a-5p on ST6Gal1 expression. The role of ST6Gal1 in regulating α2,6-sialylated integrin β1 and its significance in the activation of integrin β1/focal adhesion kinase (FAK) signaling pathway were also explored.

RESULTS

ST6Gal1 was observed to be highly expressed in GTD. Overexpression of ST6Gal1 promoted the proliferation and stemness of HTR-8/SVneo cells, whereas knockdown of ST6Gal1 suppressed the viability and stemness of JAR cells. MiR-199a-5p targeted and inhibited the expression of ST6Gal1 in trophoblastic cells. In addition, we revealed integrin β1 was highly α2,6-sialylated in JAR cells. Inhibition of ST6Gal1 reduced α2,6-sialylation on integrin β1 and suppressed the integrin β1/FAK pathway in JAR cells, thereby affecting its biological functions.

DISCUSSION

This study demonstrated that ST6Gal1 plays important roles in promoting proliferation and stemness through the integrin β1 signaling pathway in GTD. Therefore, ST6Gal1 may have a potential role in the occurrence and development of GTD.

The functional roles of protein glycosylation in human maternal-fetal crosstalk

BACKGROUND

The establishment of maternal-fetal crosstalk is vital to a successful pregnancy. Glycosylation is a post-translational modification in which glycans (monosaccharide chains) are attached to an organic molecule. Glycans are involved in many physiological and pathological processes. Human endometrial epithelium, endometrial gland secretions, decidual immune cells, and trophoblasts are highly enriched with glycoconjugates and glycan-binding molecules important for a healthy pregnancy. Aberrant glycosylation in the placenta and uterus has been linked to repeated implantation failure and various pregnancy complications, but there is no recent review summarizing the functional roles of glycosylation at the maternal-fetal interface and their associations with pathological processes.

OBJECTIVE AND RATIONALE

This review aims to summarize recent findings on glycosylation, glycosyltransferases, and glycan-binding receptors at the maternal-fetal interface, and their involvement in regulating the biology and pathological conditions associated with endometrial receptivity, placentation and maternal-fetal immunotolerance. Current knowledge limitations and future insights into the study of glycobiology in reproduction are discussed.

SEARCH METHODS

A comprehensive PubMed search was conducted using the following keywords: glycosylation, glycosyltransferases, glycan-binding proteins, endometrium, trophoblasts, maternal-fetal immunotolerance, siglec, selectin, galectin, repeated implantation failure, early pregnancy loss, recurrent pregnancy loss, preeclampsia, and fetal growth restriction. Relevant reports published between 1980 and 2023 and studies related to these reports were retrieved and reviewed. Only publications written in English were included.

OUTCOMES

The application of ultrasensitive mass spectrometry tools and lectin-based glycan profiling has enabled characterization of glycans present at the maternal-fetal interface and in maternal serum. The endometrial luminal epithelium is covered with highly glycosylated mucin that regulates blastocyst adhesion during implantation. In the placenta, fucose and sialic acid residues are abundantly presented on the villous membrane and are essential for proper placentation and establishment of maternal-fetal immunotolerance. Glycan-binding receptors, including selectins, sialic-acid-binding immunoglobulin-like lectins (siglecs) and galectins, also modulate implantation, trophoblast functions and maternal-fetal immunotolerance. Aberrant glycosylation is associated with repeated implantation failure, early pregnancy loss and various pregnancy complications. The current limitation in the field is that most glycobiological research relies on association studies, with few studies revealing the specific functions of glycans. Technological advancements in analytic, synthetic and functional glycobiology have laid the groundwork for further exploration of glycans in reproductive biology under both physiological and pathological conditions.

WIDER IMPLICATIONS

A deep understanding of the functions of glycan structures would provide insights into the molecular mechanisms underlying their involvement in the physiological and pathological regulation of early pregnancy. Glycans may also potentially serve as novel early predictive markers and therapeutic targets for repeated implantation failure, pregnancy loss, and other pregnancy complications.

Protein glycosylation: bridging maternal-fetal crosstalk during embryo implantation†

Infertility is a challenging health problem that affects 8-15% of couples worldwide. Establishing pregnancy requires successful embryo implantation, but about 85% of unsuccessful pregnancies are due to embryo implantation failure or loss soon after. Factors crucial for successful implantation include invasive blastocysts, receptive endometrium, invasion of trophoblast cells, and regulation of immune tolerance at the maternal-fetal interface. Maternal-fetal crosstalk, which relies heavily on protein-protein interactions, is a critical factor in implantation that involves multiple cellular communication and molecular pathways. Glycosylation, a protein modification process, is closely related to cell growth, adhesion, transport, signal transduction, and recognition. Protein glycosylation plays a crucial role in maternal-fetal crosstalk and can be divided into N-glycosylation and O-glycosylation, which are often terminated by sialylation or fucosylation. This review article examines the role of protein glycosylation in maternal-fetal crosstalk based on two transcriptome datasets from the GEO database (GSE139087 and GSE113790) and existing research, particularly in the context of the mechanism of protein glycosylation and embryo implantation. Dysregulation of protein glycosylation can lead to adverse pregnancy outcomes, such as missed abortion and recurrent spontaneous abortion, underscoring the importance of a thorough understanding of protein glycosylation in the diagnosis and treatment of female reproductive disorders. This knowledge could have significant clinical implications, leading to the development of more effective diagnostic and therapeutic approaches for these conditions.

miR-27b targets MAIP1 to mediate lipid accumulation in cultured human and mouse hepatic cells

Non-alcoholic liver disease (NAFLD) is a condition caused by excessive fat accumulation in the liver and developed via multiple pathways. miR-27b has been suggested to play crucial roles in the development of NAFLD, assuming via targeting genes involved in lipid catabolism and anabolism. However, other pathways regulated by miR-27b are largely unknown. Here we show that lipid accumulation was induced in miR-27b-transfected human and mouse hepatic cells and that knockdowns of three miR-27b-target genes, β-1,4-galactosyltransferase 3 (B4GALT3), matrix AAA peptidase interacting protein 1 (MAIP1) and PH domain and leucine rich repeat protein phosphatase 2 (PHLPP2), induced lipid accumulation. We also show that B4GALT3 and MAIP1 were direct targets of miR-27b and overexpression of MAIP1 ameliorated miR-27b-induced lipid accumulation. In addition, we show that hepatic Maip1 expression declined in mice fed a high-fat diet, suggesting the involvement of decreased Maip1 expression in the condition of fatty liver. Overall, we identified MAIP1/miR-27b axis as a mediator of hepatic lipid accumulation, a potential therapeutic target for NAFLD.

Roles of N-linked glycosylation and glycan-binding proteins in placentation: trophoblast infiltration, immunomodulation, angiogenesis, and pathophysiology

Protein N-linked glycosylation is a structurally diverse post-translational modification that stores biological information in a larger order of magnitude than other post-translational modifications such as phosphorylation, ubiquitination and acetylation. This gives N-glycosylated proteins a diverse range of properties and allows glyco-codes (glycan-related information) to be deciphered by glycan-binding proteins (GBPs). The intervillous space of the placenta is richly populated with membrane-bound and secreted glycoproteins. Evidence exists to suggest that altering the structural nature of their N-glycans can impact several trophoblast functions, which include those related to interactions with decidual cells. This review summarizes trophoblast-related activities influenced by N-glycan-GBP recognition, exploring how different subtypes of trophoblasts actively adapt to characteristics of the decidualized endometrium through cell-specific expression of N-glycosylated proteins, and how these cells receive decidua-derived signals via N-glycan-GBP interactions. We highlight work on how changes in N-glycosylation relates to the success of trophoblast infiltration, interactions of immunomodulators, and uterine angiogenesis. We also discuss studies that suggest aberrant N-glycosylation of trophoblasts may contribute to the pathogenesis of pregnancy complications (e.g. pre-eclampsia, early spontaneous miscarriages and hydatidiform mole). We propose that a more in-depth understanding of how N-glycosylation shapes trophoblast phenotype during early pregnancy has the potential to improve our approach to predicting, diagnosing and alleviating poor maternal/fetal outcomes associated with placental dysfunction.

Criminal of Adverse Pregnant Outcomes: A Perspective From Thyroid Hormone Disturbance Caused by SARS-CoV-2

Nowadays, emerging evidence has shown adverse pregnancy outcomes, including preterm birth, preeclampsia, cesarean, and perinatal death, occurring in pregnant women after getting infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but the underlying mechanisms remain elusive. Thyroid hormone disturbance has been unveiled consistently in various studies. As commonly known, thyroid hormone is vital for promoting pregnancy and optimal fetal growth and development. Even mild thyroid dysfunction can cause adverse pregnancy outcomes. We explored and summarized possible mechanisms of thyroid hormone abnormality in pregnant women after coronavirus disease 2019 (COVID-19) infection and made a scientific thypothesis that adverse pregnancy outcomes can be the result of thyroid hormone disorder during COVID-19. In which case, we accentuate the importance of thyroid hormone surveillance for COVID-19-infected pregnant women.

Regulation of placentation by the transforming growth factor beta superfamily†

During pregnancy, there is increased expression of some cytokines at the fetal-maternal interface; and the clarification of their roles in trophoblast-endometrium interactions is crucial to understanding the mechanism of placentation. This review addresses the up-to-date reported mechanisms by which the members of the transforming growth factor beta superfamily regulate trophoblast proliferation, differentiation, and invasion of the decidua, which are the main phases of placentation. The available information shows that these cytokines regulate placentation in somehow a synergistic and an antagonistic manner; and that dysregulation of their levels can lead to aberrant placentation. Nevertheless, prospective studies are needed to reconcile some conflicting reports; and identify some unknown mediators involved in the actions of these cytokines before their detailed mechanistic regulation of human placentation could be fully characterized. The TGF beta superfamily are expressed in the placenta, and regulate the process of placentation through the activation of several signaling pathways.

The interplay between thyroid hormones and the placenta: a comprehensive review†

Thyroid hormones (THs) regulate a number of metabolic processes during pregnancy. After implantation, the placenta forms and enhances embryonic growth and development. Dysregulated maternal THs signaling has been observed in malplacentation-mediated pregnancy complications such as preeclampsia, miscarriage, and intrauterine growth restriction (IUGR), but the molecular mechanisms involved in this association have not been fully characterized. In this review, we have discussed THs signaling and its roles in trophoblast proliferation, trophoblast differentiation, trophoblast invasion of the decidua, and decidual angiogenesis. We have also explored the relationship between specific pregnancy complications and placental THs transporters, deiodinases, and THs receptors. In addition, we have examined the effects of specific endocrine disruptors on placental THs signaling. The available evidence indicates that THs signaling is involved in the formation and functioning of the placenta and serves as the basis for understanding the pathogenesis and pathophysiology of dysthyroidism-associated pregnancy complications such as preeclampsia, miscarriage, and IUGR.

The expression of miRNA encoded by C19MC and miR-371-3 strongly varies among individual placentas but does not differ between spontaneous and induced abortions

miRNAs of the largest human miRNA gene cluster at all, i.e., C19MC, are almost exclusively expressed in the placenta. Nevertheless, only little is known about the interindividual variation of their expression and even about possible influence of gestational age, conflicting data is reported as well as for miRNAs of the much smaller miR-371-3 cluster. Our present study aims at the analyses of the expression of miRNAs from both clusters at different times of pregnancy, possible differences between placenta samples obtained from spontaneous or induced abortions in the first trimester, and the possible variation of miRNA expression at different sites within same placentas. miR-371a-3p, miR-372-3p, miR-373-3p, miR-517a-3p, and miR-520c-3p were quantified in 85 samples and miR-371a-3p was quantified in maternal serum samples taken immediately before delivery. While for miRNA-517a-3p and miR-520c-3p the expression increased with increasing gestational age, the present study revealed strong interindividual differences in the expression of miR-371-3 in full-term placental tissue as well as for miRNAs of the C19MC cluster, where the levels differed to a much lesser extent than for the former microRNAs. Also, strong interindividual differences were noted between the serum samples but differences related to the site of the placenta where the sample has been taken from were excluded. For neither of the data from placental tissue, the study revealed differences between the spontaneous and induced abortion group. Thus, the differences do not in general seem to be related to first trimester abortion. It remains to be elucidated whether or not they affect other prenatal processes.

Extracellular Vesicles Are Key Regulators of Tumor Neovasculature

Tumor progression involves a series of biologically important steps in which the crosstalk between cancer cells and the surrounding environment is an important issue. Angiogenesis is a key tumorigenic phenomenon for cancer progression. Tumor-related extracellular vesicles (EVs) modulate the tumor microenvironment (TME) through cell-to-cell communication. Tumor cells in a hypoxic TME release more EVs than cells in a normoxic environment due to uncontrollable tumor proliferation. Tumor-derived EVs in the TME influence endothelial cells (ECs), which then play multiple roles, contributing to tumor angiogenesis, loss of the endothelial vascular barrier by binding to ECs, and subsequent endothelial-to-mesenchymal transition. In contrast, they also indirectly induce tumor angiogenesis through the phenotype switching of various cells into cancer-associated fibroblasts, the activation of tumor-associated ECs and platelets, and remodeling of the extracellular matrix. Here, we review current knowledge regarding the involvement of EVs in tumor vascular-related cancer progression.

Role of galectin-glycan circuits in reproduction: from healthy pregnancy to preterm birth (PTB)

Growing evidence suggests that galectins, an evolutionarily conserved family of glycan-binding proteins, fulfill key roles in pregnancy including blastocyst implantation, maternal-fetal immune tolerance, placental development, and maternal vascular expansion, thereby establishing a healthy environment for the growing fetus. In this review, we comprehensively present the function of galectins in shaping cellular circuits that characterize a healthy pregnancy. We describe the current understanding of galectins in term and preterm labor and discuss how the galectin-glycan circuits contribute to key immunological pathways sustaining maternal tolerance and preventing microbial infections. A deeper understanding of the glycoimmune pathways regulating early events in preterm birth could offer the broader translational potential for the treatment of this devastating syndrome.

Glycan characterization of pregnancy-specific glycoprotein 1 and its identification as a novel Galectin-1 ligand

Pregnancy-specific beta 1 glycoprotein (PSG1) is secreted from trophoblast cells of the human placenta in increasing concentrations as pregnancy progresses, becoming one of the most abundant proteins in maternal serum in the third trimester. PSG1 has seven potential N-linked glycosylation sites across its four domains. We carried out glycomic and glycoproteomic studies to characterize the glycan composition of PSG1 purified from serum of pregnant women and identified the presence of complex N-glycans containing poly LacNAc epitopes with α2,3 sialyation at four sites. Using different techniques, we explored whether PSG1 can bind to galectin-1 (Gal-1) as these two proteins were previously shown to participate in processes required for a successful pregnancy. We confirmed that PSG1 binds to Gal-1 in a carbohydrate-dependent manner with an affinity of the interaction of 0.13 μM. In addition, we determined that out of the three N-glycosylation-carrying domains, only the N and A2 domains of recombinant PSG1 interact with Gal-1. Lastly, we observed that the interaction between PSG1 and Gal-1 protects this lectin from oxidative inactivation and that PSG1 competes the ability of Gal-1 to bind to some but not all of its glycoprotein ligands.

Epiregulin promotes trophoblast epithelial-mesenchymal transition through poFUT1 and O-fucosylation by poFUT1 on uPA

Objectives

The transformation of cytotrophoblasts into mesenchymal‐like extravillous trophoblasts is necessary for successful embryo implantation, and the inadequate transformation may cause abortion. Epiregulin, which is a new growth factor, plays important roles in the reproductive processes. The glycosylation of many proteins in reproduction processes is critical. Protein O‐fucosyltransferase 1 (poFUT1) is the key enzyme for the biosynthesis of O‐fucosylation on the specific glycoproteins. Urokinase‐type plasminogen activator (uPA) contains O‐fucosylated domain on Thr¹⁸. However, the functions of epiregulin and poFUT1 in the trophoblast epithelial–mesenchymal transition (EMT) process, the regulatory mechanism of epiregulin on poFUT1 and the resulting O‐fucosylated uPA remain unclear.

Materials and methods

We employed ELISA and Western blot to detect serum levels of epiregulin and poFUT1 from non‐pregnancy women, pregnancy women and abortion patients. Using two trophoblast cell lines and a mouse pregnancy model, we investigated the underlying mechanisms of epiregulin and poFUT1 in trophoblast EMT process.

Results

Serum levels of epiregulin and poFUT1 were higher in pregnant women compared with non‐pregnant women, and their levels were significantly decreased in abortion patients compared with pregnant women. The results showed that epiregulin upregulated poFUT1 expression and increased O‐fucosylation on uPA, which further activated the PI3K/Akt signalling pathway, facilitating EMT behaviour of trophoblast cells and embryo implantation in the mouse pregnant model.

Conclusions

Level of epiregulin and poFUT1 is lower in abortion patients than early pregnancy women. Epiregulin promotes trophoblast EMT through O‐fucosylation on uPA catalysed by poFUT1. Epiregulin and poFUT1 may be suggested as the potential diagnostic biomarkers and useful treatment targets for abortion.

Circular RNA circUBXN7 represses cell growth and invasion by sponging miR-1247-3p to enhance B4GALT3 expression in bladder cancer

Circular RNAs (circRNAs) have recently been confirmed to participate in different pathological processes, including cancer progression. However, the role and precise mechanism of action of the majority of circRNAs have not been elucidated in bladder cancer (BC). Here, we identified a novel circular RNA, termed circUBXN7, which was significantly downregulated in BC tissues compared with matched nontumor tissues. Importantly, we found that decreased circUBXN7 expression was associated with pathological stage, grade and poor prognosis of BC patients. Functional experiments showed that circUBXN7 overexpression dramatically inhibited proliferation, migration and invasion in vitro and suppressed tumor growth in vivo. Mechanistically, circUBXN7 could directly bind to miR-1247-3p and reverse the oncogenic effects induced by miR-1247-3p. Furthermore, B4GALT3 was predicted and confirmed to be a target of miR-1247-3p. Rescue experiments demonstrated that circUBXN7 abrogated miR-1247-3p-mediated inhibition of B4GALT3 expression. Finally, silencing of B4GALT3 promoted proliferation and invasion of BC cells; and partially abolished the tumor suppressive effects caused by circUBXN7. Taken together, our study revealed that circUBXN7 serves as a competitive endogenous RNA of miR-1247-3p to elevate B4GALT3 expression, consequently inhibiting cell viability and invasion in BC. The circUBXN7-miR-1247-3p-B4GALT3 regulatory network may provide a new perspective for gene-based treatment strategies for BC.

The role of adiponectin in placentation and preeclampsia

Preeclampsia is not fully understood; and few biomarkers, therapeutic targets, and therapeutic agents for its management have been identified. Original investigative findings suggest that abnormal placentation triggers preeclampsia and leads to hypertension, proteinuria, endothelial dysfunction, and inflammation, which are characteristics of the disease. Because of the regulatory roles that it plays in several metabolic processes, adiponectin has become a cytokine of interest in metabolic medicine. In this review, we have discussed the role of adiponectin in trophoblast proliferation, trophoblast differentiation, trophoblast invasion of the decidua, and decidual angiogenesis, which are the major phases of placentation. Also, we have highlighted the physiological profile of adiponectin in the course of normal pregnancy. Moreover, we have discussed the involvement of adiponectin in hypertension, endothelial dysfunction, inflammation, and proteinuria. Furthermore, we have summarized the reported relationship between the maternal serum adiponectin level and preeclampsia. The available evidence indicates that adiponectin level physiologically falls as pregnancy advances, regulates placentation, and exhibits protective effects against the symptoms of preeclampsia and that while hyperadiponectinemia is evident in normal-weight preeclamptic women, hypoadiponectinemia is evident in overweight and obese preeclamptic women. Therefore, the clinical use of adiponectin as a biomarker, therapeutic target, or therapeutic agent against the disease looks promising and should be considered.

Pregnancy Galectinology: Insights Into a Complex Network of Glycan Binding Proteins

Galectins are a phylogenetically conserved family of soluble β-galactoside binding proteins, consisting of 15 different types, each with a specific function. Galectins contribute to placentation by regulating trophoblast development, migration, and invasion during early pregnancy. In addition, galectins are critical players regulating maternal immune tolerance to the embedded embryo. Recently, the role of galectins in angiogenesis during decidualization and in placenta formation has gained attention. Altered expression of galectins is associated with abnormal pregnancies and infertility. This review focuses on the role of galectins in pregnancy-associated processes and discusses the relevance of galectin-glycan interactions as potential therapeutic targets in pregnancy disorders.

FUT8 drives the proliferation and invasion of trophoblastic cells via IGF-1/IGF-1R signaling pathway

INTRODUCTION

Trophoblast proliferation and invasion are essential for embryo implantation and placentation. Protein glycosylation is one of the most common and vital post-translational modifications, regulates protein physical and biochemical properties. FUT8 is the only known fucosyltransferase responsible for catalyzing α1,6-fucosylation in mammals, and α1,6-fucosylated glycoproteins are found to participate in various physiopathological processes. However, whether FUT8/α1,6-fucosylation modulates the functions of trophoblastic cells remains elusive.

METHODS

FUT8 in human placenta villi during 6-8 gestational weeks and trophoblastic cells were detected by Western blot and immunofluorescent staining. α1,6-fucosylation in tissues or cells were measured by Lectin LCA (Lens culinaris) fluorescent staining and Lectin blot. FUT8 expression was down-regulated by siRNA transfection in JAR and JEG-3 cells, and cell viability, motility and invasiveness ability were detected by the functional experiments. α1,6-fucosylation of insulin-like growth factor receptor (IGF-1R) was examined by immunoprecipitation, and the amount of phosphorylated IGF-1R was detected in FUT8 down-regulated JAR cells.

RESULTS

Human placenta villi and trophoblastic cells expressed FUT8/α1,6-fucosylation. Knockdown FUT8 by siRNA transfection suppressed the proliferation, epithelial-mesenchymal transition, migration and invasion of JAR and JEG-3 cells. Furthermore, we found that FUT8 modified the α1,6-fucosylation of IGF-1R, and regulated IGF-1 dependent activation of IGF-1R, MAPK and PI3K/Akt signaling pathways in JAR cells.

CONCLUSIONS

Our results implicate a critical role for FUT8 in maintaining the normal functions of trophoblastic cells, suggesting manipulating FUT8 may be an effective approach in pregnancy.

Integrin β1 is bound to galectin-1 in human trophoblast

Interaction of sugar binding proteins-galectins, with glycoconjugates is considered relevant for various reproductive processes. Galectin-1 (gal-1) is a molecule involved in trophoblast cell invasion, which is accomplished through interaction with cell surface and/or extracellular matrix glycoproteins. A possibility of interaction of endogenous gal-1 and trophoblast β1 integrins, both previously shown relevant for trophoblast invasion, was investigated. Confocal microscopy showed overlap in gal-1 and β1 integrin localization at the plasma membrane of isolated cytotrophoblast, HTR-8/SVneo extravillous trophoblast cell line and JAr choriocarcinoma cells. Immunoprecipitation confirmed an interaction of gal-1 with integrin β1, but not with α1 or α5 integrin subunits. Nondenaturing electrophoresis and subcellular fractionation suggested association of gal-1 with β1 integrin in intracellular and plasma membrane compartments of HTR-8/SVneo cells. Gal-1/β1 integrin complex was sensitive to chemical and enzyme treatments, indicating carbohydrate dependent interaction. Down-regulation of gal-1 by siRNA, however, had no effect on level or distribution of β1 integrin, as determined by qPCR and flow cytometry. These results suggest complex lectin type interaction of gal-1 with β1 integrin at the trophoblast cell membrane, which could influence trophoblast cell adhesion, migration and invasion.

Tumor-derived exosomal miR-1247-3p induces cancer-associated fibroblast activation to foster lung metastasis of liver cancer

The communication between tumor-derived elements and stroma in the metastatic niche has a critical role in facilitating cancer metastasis. Yet, the mechanisms tumor cells use to control metastatic niche formation are not fully understood. Here we report that in the lung metastatic niche, high-metastatic hepatocellular carcinoma (HCC) cells exhibit a greater capacity to convert normal fibroblasts to cancer-associated fibroblasts (CAFs) than low-metastatic HCC cells. We show high-metastatic HCC cells secrete exosomal miR-1247-3p that directly targets B4GALT3, leading to activation of β1-integrin–NF-κB signaling in fibroblasts. Activated CAFs further promote cancer progression by secreting pro-inflammatory cytokines, including IL-6 and IL-8. Clinical data show high serum exosomal miR-1247-3p levels correlate with lung metastasis in HCC patients. These results demonstrate intercellular crosstalk between tumor cells and fibroblasts is mediated by tumor-derived exosomes that control lung metastasis of HCC, providing potential targets for prevention and treatment of cancer metastasis.

How tumor cells control metastatic niche formation is not fully understood. Here, the authors show in a lung metastatic niche, high-metastatic hepatocellular carcinoma cells secrete exosomal miR-1247-3p that leads to activation of β1-integrin-NF-κBsignalling, converting fibroblasts to cancer-associated fibroblasts.

Calreticulin Is Involved in Invasion of Human Extravillous Trophoblasts Through Functional Regulation of Integrin β1

Calreticulin (CRT), a molecular chaperone in the endoplasmic reticulum (ER), plays a variety of roles in cell growth, differentiation, apoptosis, immunity, and cancer biology. It has been reported that CRT is expressed in the human placenta, although its function in placental development is poorly understood. Appropriate invasion of extravillous trophoblasts (EVTs) into the maternal decidua is necessary for successful pregnancy. The objective of the present study was to investigate the expression and functional role of CRT in EVTs using the human EVT cell line HTR8/SVneo, in which CRT gene expression was knocked down. We found that CRT was highly expressed in the human placenta in the early stage of pregnancy and localized to the EVTs. CRT knockdown markedly suppressed the invasion ability of HTR8/SVneo cells. Furthermore, the adhesion to fibronectin was suppressed in the CRT-knockdown cells via the dysfunction of integrin α5β1. In the CRT-knockdown cells, terminal sialylation and fucosylation were decreased, and the core galactose-containing structure was increased in the N-glycans of integrin β1. In addition, the expression levels of several critical glycosyltransferases were changed in the CRT-knockdown cells, consistent with the changes in the N-glycans. These results showed that CRT regulates the function of integrin β1 by affecting the synthesis of N-glycans in HTR8/SVneo cells. Collectively, the results of the present study demonstrate that the ER chaperone CRT plays a regulatory role in the invasion of EVTs, suggesting the importance of CRT expression in placental development during early pregnancy.

Identification of Mutations in Myocilin and Beta-1,4-galactosyltransferase 3 Genes in a Chinese Family with Primary Open-angle Glaucoma

BACKGROUND

Glaucoma is a major cause of irreversible blindness worldwide. There is evidence showing that a subset of the disease is genetically determined. In this study, we screened for mutations in chromosome 1q-linked open-angle glaucoma (GLC1A) in a Chinese family with primary open-angle glaucoma (POAG).

METHODS

A total of 23 members from five generations of a family were enrolled and underwent thorough ophthalmologic examinations. In addition, 200 unrelated healthy Chinese controls were also recruited as normal control. GLC1A gene was amplified by polymerase chain reaction, and DNA sequencing was performed to screen for mutations.

RESULTS

Six members were diagnosed as POAG, with severe clinical manifestations, and history of high intraocular pressures. The mean age of disease onset was 26.3 years. However, the others were asymptomatic. In six affected and three asymptomatic members, gene sequencing revealed a mutation c.C1456T in exon 3 of myocilin gene (MYOC). Furthermore, we also identified a novel mutation c.G322A in beta-1,4-galactosyltransferase 3 (B4GALT3) gene in all six affected and three asymptomatic members, which was not reported previously in POAG patients. The two newly identified variants were absent in other family members as well as controls.

CONCLUSION

The mutations c.1456C < T (p.L486F) in MYOC and c.322G < A (p.V108I) in B4GALT3 are likely responsible for the pathogenesis of POAG in this family.

Gene-based analysis of regulatory variants identifies 4 putative novel asthma risk genes related to nucleotide synthesis and signaling

BACKGROUND

Hundreds of genetic variants are thought to contribute to variation in asthma risk by modulating gene expression. Methods that increase the power of genome-wide association studies (GWASs) to identify risk-associated variants are needed.

OBJECTIVE

We sought to develop a method that aggregates the evidence for association with disease risk across expression quantitative trait loci (eQTLs) of a gene and use this approach to identify asthma risk genes.

METHODS

We developed a gene-based test and software package called EUGENE that (1) is applicable to GWAS summary statistics; (2) considers both cis- and trans-eQTLs; (3) incorporates eQTLs identified in different tissues; and (4) uses simulations to account for multiple testing. We applied this approach to 2 published asthma GWASs (combined n = 46,044) and used mouse studies to provide initial functional insights into 2 genes with novel genetic associations.

RESULTS

We tested the association between asthma and 17,190 genes that were found to have cis- and/or trans-eQTLs across 16 published eQTL studies. At an empirical FDR of 5%, 48 genes were associated with asthma risk. Of these, for 37, the association was driven by eQTLs located in established risk loci for allergic disease, including 6 genes not previously implicated in disease cause (eg, LIMS1, TINF2, and SAFB). The remaining 11 significant genes represent potential novel genetic associations with asthma. The association with 4 of these replicated in an independent GWAS: B4GALT3, USMG5, P2RY13, and P2RY14, which are genes involved in nucleotide synthesis or nucleotide-dependent cell activation. In mouse studies, P2ry13 and P2ry14-purinergic receptors activated by adenosine 5-diphosphate and UDP-sugars, respectively-were upregulated after allergen challenge, notably in airway epithelial cells, eosinophils, and neutrophils. Intranasal exposure with receptor agonists induced the release of IL-33 and subsequent eosinophil infiltration into the lungs.

CONCLUSION

We identified novel associations between asthma and eQTLs for 4 genes related to nucleotide synthesis/signaling and demonstrated the power of gene-based analyses of GWASs.

B4GALT3 up-regulation by miR-27a contributes to the oncogenic activity in human cervical cancer cells

β-1,4-Galactosyltransferase III (B4GALT3) is an enzyme responsible for the generation of poly-N-acetyllactosamine and is involved in tumorigenesis. However, B4GALT3-dysregulation and its role in cervical cancer cells are unknown. Herein, we found that B4GALT3 was upregulated in cervical cancer tissues compared to adjacent non-tumor tissues. B4GALT3-overexpression promoted, whereas B4GALT3-knockdown suppressed the cellular migration, invasion and EMT of HeLa and C33A cervical cancer cells. To explore the mechanism of dysregulation, B4GALT3 was predicted to be a target of miR-27a. EGFP and pGL3-promoter reporter assay showed miR-27a binds to B4GALT3 3'UTR region but enhanced its expression. RT-qPCR showed miR-27a was also upregulated and presented positive correlation with B4GALT3-expression in cervical cancer tissues. miR-27a-overexpression promoted, but blocking-miR-27a repressed these malignancies in HeLa and C33A cells. Furthermore, shR-B4GALT3 counteracted the promotion of malignancies induced by miR-27a, suggesting miR-27a upregulates B4GALT3 to enhance tumorigenic activities. In addition, we found that B4GALT3 significantly enhances β1-integrin stability, thus mediating promotion of B4GALT3 on malignancy in cervical cancer cells. Altogether, our findings evidenced that B4GALT3 upregulated by miR-27a contributes to the tumorigenic activities by β1-integrin pathway and might provide potential biomarkers for cervical cancer.

Intrauterine trophoblast migration: A comparative view of humans and rodents

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.

CCN1 (CYR61) and CCN3 (NOV) signaling drives human trophoblast cells into senescence and stimulates migration properties

During placental development, continuous invasion of trophoblasts into the maternal compartment depends on the support of proliferating extravillous trophoblasts (EVTs). Unlike tumor cells, EVTs escape from the cell cycle before invasion into the decidua and spiral arteries. This study focused on the regulation properties of glycosylated and non-glycosylated matricellular CCN1 and CCN3, primarily for proliferation control in the benign SGHPL-5 trophoblast cell line, which originates from the first-trimester placenta. Treating SGHPL-5 trophoblast cells with the glycosylated forms of recombinant CCN1 and CCN3 decreased cell proliferation by bringing about G0/G1 cell cycle arrest, which was accompanied by the upregulation of activated Notch-1 and its target gene p21. Interestingly, both CCN proteins increased senescence-associated β-galactosidase activity and the expression of the senescence marker p16. The migration capability of SGHPL-5 cells was mostly enhanced in response to CCN1 and CCN3, by the activation of FAK and Akt kinase but not by the activation of ERK1/2. In summary, both CCN proteins play a key role in regulating trophoblast cell differentiation by inducing senescence and enhancing migration properties. Reduced levels of CCN1 and CCN3, as found in early-onset preeclampsia, could contribute to a shift from invasive to proliferative EVTs and may explain their shallow invasion properties in this disease.