Core fucosylation of μ heavy chains regulates assembly and intracellular signaling of precursor B cell receptors

Roles of core fucosylation modification in immune system and diseases

Core fucosylation, catalyzed by α1,6-fucosyltransferase (FUT8), is an important N-glycosylation modification process that attaches a fucose residue via an α1,6-linkage to the core N-acetylglucosamine of N-glycans in mammals. Research over the past three decades has revealed the critical role of FUT8-mediated core fucosylation modification in various physiological and pathological processes, including cell growth, adhesion, receptor activation, antibody-dependent cellular cytotoxicity (ADCC), tumor metastasis and infections. This review discusses the immune system function involving FUT8 and the mechanisms by which core fucosylation regulates immunity and contributes to disease. A deeper understanding of these mechanisms can provide insights into cellular biology and suggest new therapeutic approaches and targets for related diseases.

Core fucosylation regulates the ovarian response via FSH receptor during follicular development

INTRODUCTION

Ovarian low response to follicle-stimulating hormone (FSH) causes infertility featuring hypergonadotropic hypogonadism, ovarian failure, and/or defective ovarian response.

OBJECTIVES

N-glycosylation is essential for FSH receptor (FSHR). Core fucosylation catalyzed by fucosyltransferase 8 (FUT8) is the most common N-glycosylation. Core fucosylation level changes between individuals and plays important roles in multiple physiological and pathological conditions. This study aims to elucidate the significance of FUT8 to modulate FSHR function in female fertility.

METHODS

Samples from patients classified as poor ovary responders (PORs) were detected with lectin blot and real-time PCR. Fut8 gene knockout (Fut8-/-) mice and FUT8-knockdown human granulosa cell line (KGN-KD) were established and in vitro fertilization (IVF) assay, western blot, molecular interaction, immunofluorescence and immunoprecipitation were applied.

RESULTS

Core fucosylation is indispensable for oocyte and follicular development. FSHR is a highly core-fucosylated glycoprotein. Loss of core fucosylation suppressed binding of FSHR to FSH, and attenuated FSHR downstream signaling in granulosa cells. Transcriptomic analysis revealed the downregulation of several transcripts crucial for oocyte meiotic progression and preimplantation development in Fut8-/- mice and in POR patients. Furthermore, loss of FUT8 inhibited the interaction between granulosa cells and oocytes, reduced transzonal projection (TZP) formation and caused poor developmental competence of oocytes after fertilization in vitro. While L-fucose administration increased the core fucosylation of FSHR, and its sensitivity to FSH.

CONCLUSION

This study first reveals a significant presence of core fucosylation in female fertility control. Decreased fucosylation on FSHR reduces the interaction of FSH-FSHR and subsequent signaling, which is a feature of the POR patients. Our results suggest that core fucosylation controls oocyte and follicular development via the FSH/FSHR pathway and is essential for female fertility in mammals.

Interplay between de novo and salvage pathways of GDP-fucose synthesis

GDP-fucose is synthesised via two pathways: de novo and salvage. The first uses GDP-mannose as a substrate, and the second uses free fucose. To date, these pathways have been considered to work separately and not to have an influence on each other. We report the mutual response of the de novo and salvage pathways to the lack of enzymes from a particular route of GDP-fucose synthesis. We detected different efficiencies of GDP-fucose and fucosylated structure synthesis after a single inactivation of enzymes of the de novo pathway. Our study demonstrated the unequal influence of the salvage enzymes on the production of GDP-fucose by enzymes of the de novo biosynthesis pathway. Simultaneously, we detected an elevated level of one of the enzymes of the de novo pathway in the cell line lacking the enzyme of the salvage biosynthesis pathway. Additionally, we identified dissimilarities in fucose uptake between cells lacking TSTA3 and GMDS proteins.

Revisiting the immunopathology of congenital disorders of glycosylation: an updated review

Glycosylation is a critical post-translational modification that plays a pivotal role in several biological processes, such as the immune response. Alterations in glycosylation can modulate the course of various pathologies, such as the case of congenital disorders of glycosylation (CDG), a group of more than 160 rare and complex genetic diseases. Although the link between glycosylation and immune dysfunction has already been recognized, the immune involvement in most CDG remains largely unexplored and poorly understood. In this study, we provide an update on the immune dysfunction and clinical manifestations of the 12 CDG with major immune involvement, organized into 6 categories of inborn errors of immunity according to the International Union of Immunological Societies (IUIS). The immune involvement in phosphomannomutase 2 (PMM2)-CDG - the most frequent CDG - was comprehensively reviewed, highlighting a higher prevalence of immune issues during infancy and childhood and in R141H-bearing genotypes. Finally, using PMM2-CDG as a model, we point to links between abnormal glycosylation patterns in host cells and possibly favored interactions with microorganisms that may explain the higher susceptibility to infection. Further characterizing immunopathology and unusual host-pathogen adhesion in CDG can not only improve immunological standards of care but also pave the way for innovative preventive measures and targeted glycan-based therapies that may improve quality of life for people living with CDG.

The Multifaceted Role of FUT8 in Tumorigenesis: From Pathways to Potential Clinical Applications

FUT8, the sole glycosyltransferase responsible for N-glycan core fucosylation, plays a crucial role in tumorigenesis and development. Aberrant FUT8 expression disrupts the function of critical cellular components and triggers the abnormality of tumor signaling pathways, leading to malignant transformations such as proliferation, invasion, metastasis, and immunosuppression. The association between FUT8 and unfavorable outcomes in various tumors underscores its potential as a valuable diagnostic marker. Given the remarkable variation in biological functions and regulatory mechanisms of FUT8 across different tumor types, gaining a comprehensive understanding of its complexity is imperative. Here, we review how FUT8 plays roles in tumorigenesis and development, and how this outcome could be utilized to develop potential clinical therapies for tumors.

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.

The role of N-glycosylation in B-cell biology and IgG activity. The aspects of autoimmunity and anti-inflammatory therapy

The immune system is strictly regulated by glycosylation through the addition of highly diverse and dynamically changing sugar structures (glycans) to the majority of immune cell receptors. Although knowledge in the field of glycoimmunology is still limited, numerous studies point to the key role of glycosylation in maintaining homeostasis, but also in reflecting its disruption. Changes in oligosaccharide patterns can lead to impairment of both innate and acquired immune responses, with important implications in the pathogenesis of diseases, including autoimmunity. B cells appear to be unique within the immune system, since they exhibit both innate and adaptive immune activity. B cell surface is rich in glycosylated proteins and lectins which recognise glycosylated ligands on other cells. Glycans are important in the development, selection, and maturation of B cells. Changes in sialylation and fucosylation of cell surface proteins affect B cell signal transduction through BCRs, CD22 inhibitory coreceptor and Siglec-G. Plasmocytes, as the final stage of B cell differentiation, produce and secrete immunoglobulins (Igs), of which IgGs are the most abundant N-glycosylated proteins in human serum with the conserved N-glycosylation site at Asn297. N-oligosaccharide composition of the IgG Fc region affects its secretion, structure, half-life and effector functions (ADCC, CDC). IgG N-glycosylation undergoes little change during homeostasis, and may gradually be modified with age and during ongoing inflammatory processes. Hyperactivated B lymphocytes secrete autoreactive antibodies responsible for the development of autoimmunity. The altered profile of IgG N-glycans contributes to disease progression and remission and is sensitive to the application of therapeutic substances and immunosuppressive agents. In this review, we focus on the role of N-glycans in B-cell biology and IgG activity, the rearrangement of IgG oligosaccharides in aging, autoimmunity and immunosuppressive therapy.

Glycome dynamics in T and B cell development: basic immunological mechanisms and clinical applications

Glycans cover the surfaces of all mammalian cells through a process called glycosylation. Nearly all proteins and receptors that integrate the intricate series of co-stimulatory/inhibitory pathways of the immune system are glycosylated. Growing evidence indicates that the development of the immune system at the origins of T and B cell development is tightly regulated by glycosylation. In this opinion, we hypothesize that the glycome composition of developing T and B cells is developmentally regulated. We discuss how glycans play fundamental roles in lymphocyte development and how glycans early define T and B cell functionality in multiple aspects of adaptive immunity. These advances can provide opportunities for the discovery of novel disease factors and more effective candidate treatments for various conditions.

Targeting Post-Translational Modifications to Improve Combinatorial Therapies in Breast Cancer: The Role of Fucosylation

Various tumors rely on post-translational modifications (PTMs) to promote invasiveness and angiogenesis and to reprogram cellular energetics to abate anti-cancer immunity. Among PTMs, fucosylation is a particular type of glycosylation that has been linked to different aspects of immune and hormonal physiological functions as well as hijacked by many types of tumors. Multiple tumors, including breast cancer, have been linked to dismal prognoses and increased metastatic potential due to fucosylation of the glycan core, namely core-fucosylation. Pre-clinical studies have examined the molecular mechanisms regulating core-fucosylation in breast cancer models, its negative prognostic value across multiple disease stages, and the activity of in vivo pharmacological inhibition, instructing combinatorial therapies and translation into clinical practice. Throughout this review, we describe the role of fucosylation in solid tumors, with a particular focus on breast cancer, as well as physiologic conditions on the immune system and hormones, providing a view into its potential as a biomarker for predicating or predicting cancer outcomes, as well as a potential clinical actionability as a biomarker.

Synthetic nanobodies as tools to distinguish IgG Fc glycoforms

Protein glycosylation is a crucial mediator of biological functions and is tightly regulated in health and disease. However, interrogating complex protein glycoforms is challenging, as current lectin tools are limited by cross-reactivity while mass spectrometry typically requires biochemical purification and isolation of the target protein. Here, we describe a method to identify and characterize a class of nanobodies that can distinguish glycoforms without reactivity to off-target glycoproteins or glycans. We apply this technology to immunoglobulin G (IgG) Fc glycoforms and define nanobodies that specifically recognize either IgG lacking its core-fucose or IgG bearing terminal sialic acid residues. By adapting these tools to standard biochemical methods, we can clinically stratify dengue virus and SARS-CoV-2 infected individuals based on their IgG glycan profile, selectively disrupt IgG-Fcγ receptor binding both in vitro and in vivo, and interrogate the B cell receptor (BCR) glycan structure on living cells. Ultimately, we provide a strategy for the development of reagents to identify and manipulate IgG Fc glycoforms.

Core Fucosylation Regulates the Function of Pre-BCR, BCR and IgG in Humoral Immunity

Most of the membrane molecules involved in immune response are glycosylated. N-glycans linked to asparagine (Asn) of immune molecules contribute to the protein conformation, surface expression, stability, and antigenicity. Core fucosylation catalyzed by core fucosyltransferase (FUT8) is the most common post-translational modification. Core fucosylation is essential for evoking a proper immune response, which this review aims to communicate. First, FUT8 deficiency suppressed the interaction between μHC and λ5 during pre-BCR assembly is given. Second, we described the effects of core fucosylation in B cell signal transduction via BCR. Third, we investigated the role of core fucosylation in the interaction between helper T (T_H) cells and B cells. Finally, we showed the role of FUT8 on the biological function of IgG. In this review, we discussed recent insights into the sites where core fucosylation is critical for humoral immune responses.

Keratan sulfate-based glycomimetics using Langerin as a target for COPD: lessons from studies on Fut8 and core fucose

Glycosylation represents one of the most abundant posttranslational modification of proteins. Glycosylation products are diverse and are regulated by the cooperative action of various glycosyltransferases, glycosidases, substrates thereof: nucleoside sugars and their transporters, and chaperons. In this article, we focus on a glycosyltransferase, α1,6-fucosyltransferase (Fut8) and its product, the core fucose structure on N-glycans, and summarize the potential protective functions of this structure against emphysema and chronic obstructive pulmonary disease (COPD). Studies of FUT8 and its enzymatic product, core fucose, are becoming an emerging area of interest in various fields of research including inflammation, cancer and therapeutics. This article discusses what we can learn from studies of Fut8 and core fucose by using knockout mice or in vitro studies that were conducted by our group as well as other groups. We also include a discussion of the potential protective functions of the keratan sulfate (KS) disaccharide, namely L4, against emphysema and COPD as a glycomimetic. Glycomimetics using glycan analogs is one of the more promising therapeutics that compensate for the usual therapeutic strategy that involves targeting the genome and the proteome. These typical glycans using KS derivatives as glycomimetics, will likely become a clue to the development of novel and effective therapeutic strategies.

The Role of Glycosylation in Inflammatory Diseases

The diversity of glycan presentation in a cell, tissue and organism is enormous, which reflects the huge amount of important biological information encoded by the glycome which has not been fully understood. A compelling body of evidence has been highlighting the fundamental role of glycans in immunity, such as in development, and in major inflammatory processes such as inflammatory bowel disease, systemic lupus erythematosus and other autoimmune disorders. Glycans play an instrumental role in the immune response, integrating the canonical circuits that regulate innate and adaptive immune responses. The relevance of glycosylation in immunity is demonstrated by the role of glycans as important danger-associated molecular patterns and pathogen-associated molecular patterns associated with the discrimination between self and non-self; also as important regulators of the threshold of T cell activation, modulating receptors signalling and the activity of both T and other immune cells. In addition, glycans are important determinants that regulate the dynamic crosstalk between the microbiome and immune response. In this chapter, the essential role of glycans in the immunopathogenesis of inflammatory disorders will be presented and its potential clinical applications (diagnosis, prognosis and therapeutics) will be highlighted.

Loss of core fucosylation enhances the anticancer activity of cytotoxic T lymphocytes by increasing PD-1 degradation

As an immune checkpoint, programmed cell death 1 (PD-1) and its ligand (PD-L1) pathway plays a crucial role in CD8⁺ cytotoxic T lymphocytes (CTL) activation and provides antitumor responses. The N-glycans of PD-1 and PD-L1 are highly core fucosylated, which are solely catalyzed by the core fucosyltransferase (Fut8). However, the precise biological mechanisms underlying effects of core fucosylation of PD-1 and PD-L1 on CTL activation have not been fully understood. In this study, we found that core fucosylation was significantly upregulated in lung adenocarcinoma. Compared to those of Fut8^+/+ OT-I mice, the lung adenocarcinoma formation induced by urethane was markedly reduced in Fut8^-/- OT-I mice. De-core fucosylation of PD-1 compromised its expression on Fut8^-/- CTL, resulted in enhanced Fut8^-/- CTL activation and cytotoxicity, leading to more efficient tumor eradication. Indeed, loss of core fucosylation significantly enhanced the PD-1 ubiquitination and in turn led to the degradation of PD-1 in the proteasome. Our current work indicates that inhibition of core fucosylation is a unique strategy to reduce PD-1 expression for the antilung adenocarcinoma immune therapy in the future.

A novel immunochromatographic strips assay for rapid and simple detection of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex multi-system autoimmune disease. Detection of anti-nuclear antibodies (ANA) is fundamental for the diagnosis of SLE. In the present study, we found that the level of core fucosylation catalyzed by α1,6-fucosyltransferase (Fut8) is markedly up-regulated on immunoglobulin G (IgG) in the sera of SLE patients detected by Aspergillus oryzae lectin (AOL) blot. In sandwich Dot enzyme-linked immunosorbent assay (Dot-ELISA), the core fucosylation level was also found significantly increased in the sera from SLE patients with a higher ANA titer. To establish a rapid and sensitive laboratory test for the diagnosis of SLE, we prokaryotically expressed AOL and C3-D1-C3-D2-C3 of protein G (SpG3), and generate AOL-conjugated colloid gold immunochromatographic strips (ICS). The detection limit of core fucosylated IgG was 10 μg/mL for AOL-conjugated colloid gold ICS. As well as indirect immunofluorescence, the AOL-conjugated colloid gold ICS showed reliable results in the serum of 39 SLE patients. Our results indicated that the AOL-conjugated colloid gold ICS could serve as a rapid test for the detection of ANA and suspected cases of SLE.

N-Glycan Branching Is Required for Development of Mature B Cells

Galectins have been implicated in inhibiting BCR signaling in mature B cells but promoting pre-BCR signaling during early development. Galectins bind to branched N-glycans attached to cell surface glycoproteins to control the distribution, clustering, endocytosis, and signaling of surface glycoproteins. During T cell development, N-glycan branching is required for positive selection of thymocytes, inhibiting both death by neglect and negative selection via enhanced surface retention of the CD4/CD8 coreceptors and limiting TCR clustering/signaling, respectively. The role of N-glycan branching in B cell development is unknown. In this study, we report that N-glycan branching is absolutely required for development of mature B cells in mice. Elimination of branched N-glycans in developing B cells via targeted deletion of N-acetylglucosaminyl transferase I (Mgat1) markedly reduced cellularity in the bone marrow and/or spleen and inhibited maturation of pre-, immature, and transitional stage 2 B cells. Branching deficiency markedly reduced surface expression of the pre-BCR/BCR coreceptor CD19 and promoted spontaneous death of pre-B cells and immature B cells in vitro. Death was rescued by low-dose pre-BCR/BCR stimulation but exacerbated by high-dose pre-BCR/BCR stimulation as well as antiapoptotic Bcl_xL overexpression in pre-B cells. Branching deficiency also enhanced Nur77 induction, a marker of negative selection. Together, these data suggest that, as in T cells, N-glycan branching promotes positive selection of B cells by augmenting pre-BCR/BCR signaling via CD19 surface retention, whereas limiting negative selection from excessive BCR engagement.

Loss of core fucosylation suppressed the humoral immune response in Salmonella typhimurium infected mice

BACKGROUND

The humoral immune response is pivotal to protect the host from Salmonella typhimurium (S. typhimurium) infection. Previously, we found that core fucosylation catalyzed by core fucosyltransferase (Fut8) could regulate the immune responses. However, the role of core fucosylation during S. typhimurium infection remains unclear.

METHODS

To demonstrate the role of Fut8 in S. typhimurium infection, we infected Fut8^+/+ and Fut8^-/- mice using S. typhimurium. The production of antiserum against the S. typhimurium was detected. The expression of T and B cell activation-related genes during S. typhimurium infection was analyzed. The role of core fucosylation on CD4⁺ T-B cell interaction and B cell generation was investigated during S. typhimurium infection. The production of sIgA was compared between Fut8^+/+ and Fut8^-/- mice.

RESULTS

Compared to Fut8^+/+ mice, the number of S. typhimurium colonized in the cecum was markedly increased in Fut8^-/- mice. The production of the IgG and sIgA specific for S. typhimurium was significantly decreased in Fut8^-/- mice. Moreover, loss of Fut8 decreased the induction of Th2-type cytokines from splenic cells of Fut8^-/- mice during S. typhimurium infection. In addition, we found that the core fucosylation regulated the interaction between B and T cells in the lipid raft formation.

CONCLUSION

Core fucosylation plays important roles in host defence against S. typhimurium infection.

CDG and immune response: From bedside to bench and back

Glycosylation is an essential biological process that adds structural and functional diversity to cells and molecules, participating in physiological processes such as immunity. The immune response is driven and modulated by protein-attached glycans that mediate cell-cell interactions, pathogen recognition and cell activation. Therefore, abnormal glycosylation can be associated with deranged immune responses. Within human diseases presenting immunological defects are congenital disorders of glycosylation (CDG), a family of around 130 rare and complex genetic diseases. In this review, we have identified 23 CDG with immunological involvement, characterized by an increased propensity to-often life-threatening-infection. Inflammatory and autoimmune complications were found in 7 CDG types. CDG natural history(ies) and the mechanisms behind the immunological anomalies are still poorly understood. However, in some cases, alterations in pathogen recognition and intracellular signaling (eg, TGF-β1, NFAT, and NF-κB) have been suggested. Targeted therapies to restore immune defects are only available for PGM3-CDG and SLC35C1-CDG. Fostering research on glycoimmunology may elucidate the involved pathophysiological mechanisms and open new therapeutic avenues, thus improving CDG patients' quality of life.

Carbohydrate-dependent B cell activation by fucose-binding bacterial lectins

Bacterial lectins are typically multivalent and bind noncovalently to specific carbohydrates on host tissues to facilitate bacterial adhesion. Here, we analyzed the effects of two fucose-binding lectins, BambL from Burkholderia ambifaria and LecB from Pseudomonas aeruginosa, on specific signaling pathways in B cells. We found that these bacterial lectins induced B cell activation, which, in vitro, was dependent on the cell surface expression of the B cell antigen receptor (BCR) and its co-receptor CD19, as well as on spleen tyrosine kinase (Syk) activity. The resulting release of intracellular Ca²⁺ was followed by an increase in the cell surface abundance of the activation marker CD86, augmented cytokine secretion, and subsequent cell death, replicating all of the events that are observed in vitro upon canonical and antigen-mediated B cell activation. Moreover, injection of BambL in mice resulted in a substantial, BCR-independent loss of B cells in the bone marrow with simultaneous, transient enlargement of the spleen (splenomegaly), as well as an increase in the numbers of splenic B cells and myeloid cells. Together, these data suggest that bacterial lectins can initiate polyclonal activation of B cells through their sole capacity to bind to fucose.

Core fucosylation of copper transporter 1 plays a crucial role in cisplatin-resistance of epithelial ovarian cancer by regulating drug uptake

Core fucosylation catalyzed by core fucosyltransferase (Fut8) contributes to the progressions of epithelial ovarian cancer (EOC). Copper transporter 1 (CTR1), which contains one N-glycan on Asn¹⁵ , mediates cellular transport of cisplatin (cDDP), and plays an important role in the process of cDDP-resistance in EOC. In the present study, we found that the core fucosylation level elevated significantly in the sera of cDDP-treated EOC patients. The in vitro assays also indicate that core fucosylation of CTR1 was significantly upregulated in cDDP-resistant A2780CP cells compared to the cDDP-sensitive A2780S cells. Intriguingly, the hyper core fucosylation suppressed the CTR1-cDDP interactions and cDDP-uptake into A2780CP cells. Conversely, contrast to the Fut8^+/+ mouse ovarian epithelial cells, the Fut8-deleted (Fut8^-/- ) cells obviously showed higher cDDP-uptake. Furthermore, the recovered core fucosylation induced the suppression of cDDP-uptake in Fut8-restored ovarian epithelial cells. In addition, the core fucosylation could regulate the phosphorylation of cDDP-resistance-associated molecules, such as AKT, ERK, JNK, and mTOR. Our findings suggest that the core fucosylation of CTR1 plays an important role in the cellular cDDP-uptake and thus provide new strategies for improving the outcome of cDDP based chemotherapy of EOC.

FUT 2 polymorphism and outcome in very-low-birth-weight infants

BACKGROUND

To determine whether the secretor gene fucosyltransferase (FUT)2 polymorphism G428A is predictive for adverse outcomes in a large cohort of very-low-birth weight (VLBW) infants.

METHODS

We prospectively enrolled 2,406 VLBW infants from the population-based multicenter cohort of the German Neonatal network cohort (2009-2011). The secretor genotype (rs601338) was assessed from DNA samples extracted from buccal swabs. Primary study outcomes were clinical sepsis, blood-culture confirmed sepsis, intracerebral hemorrhage (ICH), necrotizing enterocolitis (NEC) or focal intestinal perforation requiring surgery, and death.

RESULTS

Based on the assumption of a recessive genetic model, AA individuals had a higher incidence of ICH (AA: 19.0% vs.

GG/AG

14.9%, P = 0.04) which was not significant in the additive genetic model (multivariable logistic regression analysis; allele carriers: 365 cases, 1,685 controls; OR: 1.2; 95% CI: 0.99-1.4; P = 0.06). Other outcomes were not influenced by FUT2 genotype in either genetic model.

CONCLUSION

This large-scale multicenter study did not confirm previously reported associations between FUT2 genotype and adverse outcomes in preterm infants.

Core fucosylation of IgG B cell receptor is required for antigen recognition and antibody production

Ag recognition and Ab production in B cells are major components of the humoral immune response. In the current study, we found that the core fucosylation catalyzed by α1,6-fucosyltransferase (Fut8) was required for the Ag recognition of BCR and the subsequent signal transduction. Moreover, compared with the 3-83 B cells, the coalescing of lipid rafts and Ag-BCR endocytosis were substantially reduced in Fut8-knockdown (3-83-KD) cells with p31 stimulation and then completely restored by reintroduction of the Fut8 gene to the 3-83-KD cells. Indeed, Fut8-null (Fut8(-/-)) mice evoked a low immune response following OVA immunization. Also, the frequency of IgG-producing cells was significantly reduced in the Fut8(-/-) spleen following OVA immunization. Our results clearly suggest an unexpected mode of BCR function, in which the core fucosylation of IgG-BCR mediates Ag recognition and, concomitantly, cell signal transduction via BCR and Ab production.

Overexpression of α (1,6) fucosyltransferase associated with aggressive prostate cancer

Aberrant protein glycosylation is known to be associated with the development of cancers. The aberrant glycans are produced by the combined actions of changed glycosylation enzymes, substrates and transporters in glycosylation synthesis pathways in cancer cells. To identify glycosylation enzymes associated with aggressive prostate cancer (PCa), we analyzed the difference in the expression of glycosyltransferase genes between aggressive and non-aggressive PCa. Three candidate genes encoding glycosyltransferases that were elevated in aggressive PCa were subsequently selected. The expression of the three candidates was then further evaluated in androgen-dependent (LNCaP) and androgen-independent (PC3) PCa cell lines. We found that the protein expression of one of the glycosyltransferases, α (1,6) fucosyltransferase (FUT8), was only detected in PC3 cells, but not in LNCaP cells. We further showed that FUT8 protein expression was elevated in metastatic PCa tissues compared to normal prostate tissues. In addition, using tissue microarrays, we found that FUT8 overexpression was statistically associated with PCa with a high Gleason score. Using PC3 and LNCaP cells as models, we found that FUT8 overexpression in LNCaP cells increased PCa cell migration, while loss of FUT8 in PC3 cells decreased cell motility. Our results suggest that FUT8 may be associated with aggressive PCa and thus is potentially useful for its prognosis.

α1,6-Fucosylation regulates neurite formation via the activin/phospho-Smad2 pathway in PC12 cells: the implicated dual effects of Fut8 for TGF-β/activin-mediated signaling

It is well known that α1,6-fucosyltransferase (Fut8) and its products, α1,6-fucosylated N-glycans, are highly expressed in brain tissue. Recently, we reported that Fut8-knockout mice exhibited multiple behavioral abnormalities with a schizophrenia-like phenotype, suggesting that α1,6-fucosylation plays important roles in the brain and neuron system. In the present study, we screened several neural cell lines and found that PC12 cells express the highest levels of α1,6-fucosylation. The knockdown (KD) of Fut8 promoted a significant enhancement of neurite formation and induction of neurofilament expression. Surprisingly, the levels of phospho-Smad2 were greatly increased in the KD cells. Finally, we found that the activin-mediated signal pathway was essential for these changes in KD cells. Exogenous activin, not TGF-β1, induced neurite outgrowth and phospho-Smad2. In addition, the α1,6-fucosylation level on the activin receptors was greatly decreased in KD cells, while the total expression level was unchanged, suggesting that α1,6-fucosylation negatively regulated activin-mediated signaling. Furthermore, inhibition of activin receptor-mediated signaling or restoration of Fut8 expression rescued cell morphology and phospho-Smad2 levels, which were enhanced in KD cells. Considering the fact that α1,6-fucosylation is important for TGF-β-mediated signaling, the results of this study strongly suggest that Fut8 plays a dual role in TGF-β/activin-mediated signaling.