The ulcerative colitis-associated gene FUT8 regulates the quantity and quality of secreted mucins.

Mucins are the main macrocomponents of the mucus layer that protects the digestive tract from pathogens. Fucosylation of mucins increases mucus viscoelasticity and its resistance to shear stress. These properties are altered in patients with ulcerative colitis (UC), which is marked by a chronic inflammation of the distal part of the colon. Here, we show that levels of Fucosyltransferase 8 (FUT8) and specific mucins are increased in the distal inflamed colon of UC patients. Recapitulating this FUT8 overexpression in mucin-producing HT29-18N2 colonic cell line increases delivery of MUC1 to the plasma membrane and extracellular release of MUC2 and MUC5AC. Mucins secreted by FUT8 overexpressing cells are more resistant to removal from the cell surface than mucins secreted by FUT8-depleted cells (FUT8 KD). FUT8 KD causes intracellular accumulation of MUC1 and alters the ratio of secreted MUC2 to MUC5AC. These data fit well with the Fut8-/- mice phenotype, which are protected from UC. Fut8-/- mice exhibit a thinner proximal colon mucus layer with an altered ratio of neutral to acidic mucins. Together, our data reveal that FUT8 modifies the biophysical properties of mucus by controlling levels of cell surface MUC1 and quantity and quality of secreted MUC2 and MUC5AC. We suggest that these changes in mucus viscoelasticity likely facilitate bacterial-epithelial interactions leading to inflammation and UC progression.

Involvement of langerin in the protective function of a keratan sulfate-based disaccharide in an emphysema mouse model.

Chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis, is now the third cause of death worldwide, and COVID-19 infection has been reported as an exacerbation factor of them. In this study, we report that the intratracheal administration of the keratan sulfate-based disaccharide L4 mitigates the symptoms of elastase-induced emphysema in a mouse model. To know the molecular mechanisms, we performed a functional analysis of a C-type lectin receptor, langerin, a molecule that binds L4. Using mouse BMDCs (bone marrow-derived dendritic cells) as langerin-expressing cells, we observed the downregulation of IL-6 and TNFa and the upregulation of IL-10 after incubation with L4. We also identified CapG (a macrophage-capping protein) as a possible molecule that binds langerin by immunoprecipitation combined with a mass spectrometry analysis. We identified a portion of the CapG that was localized in the nucleus and binds to the promoter region of IL-6 and the TNFa gene in BMDCs, suggesting that CapG suppresses the gene expression of IL-6 and TNFa as an inhibitory transcriptional factor. To examine the effects of L4 in vivo, we also generated langerin-knockout mice by means of genome editing technology. In an emphysema mouse model, the administration of L4 did not mitigate the symptoms of emphysema as well as the inflammatory state of the lung in the langerin-knockout mice. These data suggest that the anti-inflammatory effect of L4 through the langerin-CapG axis represents a potential therapeutic target for the treatment of emphysema and COPD.

A highly specific antibody against the core fucose of the N-glycan in IgG identifies the pulmonary diseases and its regulation by CCL2.

Glycan structure is often modulated in disease or predisease states, suggesting that such changes might serve as biomarkers. Here, we generated a monoclonal antibody (mAb) against the core fucose of the N-glycan in human IgG. Notably, this mAb can be used in Western blotting and ELISA. ELISA using this mAb revealed a low level of the core fucose of the N-glycan in IgG, suggesting that the level of acore fucosylated (noncore fucosylated) IgG was increased in the sera of the patients with lung cancer, chronic obstructive pulmonary disease, and interstitial pneumonia compared to healthy subjects. In a coculture analysis using human lung adenocarcinoma A549 cells and antibody-secreting B cells, the downregulation of the FUT8 (α1,6 fucosyltransferase) gene and a low level of core fucose of the N-glycan in IgG in antibody-secreting B cells were observed after coculture. A dramatic alteration in gene expression profiles for cytokines, chemokines, and their receptors were also observed after coculturing, and we found that the identified C-C motif chemokine 2 was partially involved in the downregulation of the FUT8 gene and the low level of core fucose of the N-glycan in IgG in antibody-secreting B cells. We also developed a latex turbidimetric immunoassay using this mAb. These results suggest that communication with C-C motif chemokine 2 between lung cells and antibody-secreting B cells downregulate the level of core fucose of the N-glycan in IgG, i.e., the increased level of acore fucosylated (noncore fucosylated) IgG, which would be a novel biomarker for the diagnosis of patients with pulmonary diseases.

Possible regulation of ganglioside GD3 synthase gene expression with DNA methylation in human glioma cells.

Gangliosides are expressed in nervous systems and some neuroectoderm-derived tumors at high levels and play pivotal roles. However, mechanisms for the regulation of glycosyltransferase genes responsible for the ganglioside synthesis are not well understood. In this study, we analyzed DNA methylation patterns of promoter regions of GD3 synthase (ST8SIA1) as well as mRNA levels and ganglioside expression using human glioma cell lines. Among 5 cell lines examined, 4 lines showed changes in the expression levels of related genes after treatment with 5-aza-dC. LN319 showed up-regulation of St8sia1 and increased b-series gangliosides after 5-aza-dC treatment, and an astrocytoma cell line, AS showed high expression of ST8SIA1 and b-series gangliosides persistently before and after 5-Aza-2'-deoxycytidine treatment. Using these 2 cell lines, DNA methylation patterns of the promoter regions of the gene were analyzed by bisulfite-sequencing. Consequently, 2 regions that were methylated before 5-Aza-2'-deoxycytidine treatment were demethylated in LN319 after the treatment, while those regions were persistently demethylated in AS. These 2 regions corresponded with sites defined as promoter regions by Luciferase assay. Taken together, it was suggested that ST8SIA1 gene is regulated by DNA methylation at the promoter regions, leading to the regulation of tumor phenotypes.

N-glycan branching enzymes involved in cancer, Alzheimer's disease and COPD and future perspectives.

Over the past 3 decades, our group has been involved in studies related to the biosynthesis of N-glycan branching and related glycosyltransferases and have purified most of these Golgi-derived enzymes to homogeneity using classical purification methods and cloned the cDNA of GnT-III, IV, V, VI and Fut8 except GnT-IX(Vb) which was obtained by homology cloning. Based primarily on our data, we briefly summarize the significance of three major enzymes and discuss perspectives for future studies on the occasion of Ernesto's 90th birthday celebration.

Signaling domains of cancer-associated glycolipids.

Immunotherapy of malignant cancers is now becoming one of representative approaches to overcome cancers. To construct strategies for immunotherapy, presence of tumor-specific antigens should be a major promise. A number of cancer specific- or cancer-associated antigens have been reported based on various experimental sets and various animal systems. The most reasonable strategy to define tumor-specific antigens might be "autologous typing" performed by Old's group, proposing three classes of tumor-antigens recognized by host immune systems of cancer patients. Namely, class 1, individual antigens that is present only in the patient's sample analyzed; class 2, shared antigens that can be found only in some group of cancers in some patients, but not in normal cells and tissues; class 3, universal antigens that are present in some cancers but also in normal cells and tissues with different densities. Sen Hakomori reported there were novel carbohydrates in cancers that could not be detected in normal cells mainly by biochemical approaches. Consequently, many of class 2 cancer-specific antigens have been revealed to be carbohydrate antigens, and been used for cancer diagnosis and treatment. Not only as cancer markers, but roles of those cancer-associated carbohydrates have also been recognized as functional molecules in cancer cells. In particular, roles of complex carbohydrates in the regulation of cell signaling on the cell surface microdomains, glycolipid-enriched microdomain (GEM)/rafts have been reported by Hakomori and many other researchers including us. The processes and present status of these studies on cancer-associated glycolipids were summarized.

Lack of GD3 synthase (St8sia1) attenuates malignant properties of gliomas in genetically engineered mouse model.

High expression of gangliosides GD3 and GD2 is observed in human gliomas. The functions of GD3 and GD2 in malignant properties have been reported in glioma cells in vitro, but those functions have not yet been investigated in vivo. In this study, we showed that deficiency of GD3 synthase (GD3S, St8sia1) attenuated glioma progression and clinical and pathological features in a platelet-derived growth factor B-driven murine glioma model. Lack of GD3S resulted in the prolonged lifespan of glioma-bearing mice and low-grade pathology in generated gliomas. Correspondingly, they showed reduced phosphorylation levels of Akt, Erks, and Src family kinases in glioma tissues. A DNA microarray study revealed marked alteration in the expression of various genes, particularly in MMP family genes, in GD3S-deficient gliomas. Re-expression of GD3S restored expression of MMP9 in primary-cultured glioma cells. We also identified a transcription factor, Ap2α, expressed in parallel with GD3S expression, and showed that Ap2α was critical for the induction of MMP9 by transfection of its cDNA and luciferase reporter genes, and a ChIP assay. These findings suggest that GD3S enhances the progression of gliomas by enhancement of the Ap2α-MMP9 axis. This is the first report to describe the tumor-enhancing functions of GD3S in vivo.

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.

Synthesis and Screening of α-Xylosides in Human Glioblastoma Cells.

Glycosaminoglycans (GAGs) such as heparan sulfate and chondroitin sulfate decorate all mammalian cell surfaces. These mucopolysaccharides act as coreceptors for extracellular ligands, regulating cell signaling, growth, proliferation, and adhesion. In glioblastoma, the most common type of primary malignant brain tumor, dysregulated GAG biosynthesis results in altered chain length, sulfation patterns, and the ratio of contributing monosaccharides. These events contribute to the loss of normal cellular function, initiating and sustaining malignant growth. Disruption of the aberrant cell surface GAGs with small molecule inhibitors of GAG biosynthetic enzymes is a potential therapeutic approach to blocking the rogue signaling and proliferation in glioma, including glioblastoma. Previously, 4-azido-xylose-α-UDP sugar inhibited both xylosyltransferase (XYLT-1) and ß-1,4-galactosyltransferase-7 (ß-GALT-7)-the first and second enzymes of GAG biosynthesis-when microinjected into a cell. In another study, 4-deoxy-4-fluoro-ß-xylosides inhibited ß-GALT-7 at 1 mM concentration in vitro. In this work, we seek to solve the enduring problem of drug delivery to human glioma cells at low concentrations. We developed a library of hydrophobic, presumed prodrugs 4-deoxy-4-fluoro-2,3-dibenzoyl-(α- or ß-) xylosides and their corresponding hydrophilic inhibitors of XYLT-1 and ß-GALT-7 enzymes. The prodrugs were designed to be activatable by carboxylesterase enzymes overexpressed in glioblastoma. Using a colorimetric MTT assay in human glioblastoma cell lines, we identified a prodrug-drug pair (4-nitrophenyl-α-xylosides) as lead drug candidates. The candidates arrest U251 cell growth at an IC50 = 380 nM (prodrug), 122 µM (drug), and U87 cells at IC50 = 10.57 µM (prodrug). Molecular docking studies were consistent with preferred binding of the α- versus ß-nitro xyloside conformer to XYLT-1 and ß-GALT-7 enzymes.

Extracellular Vesicles and Glycosylation.

Extracellular vesicles (EVs), a generic term for any vesicles or particles that are released from cells, play an important role in modulating numerous biological and pathological events, including development, differentiation, aging, thrombus formation, immune responses, neurodegenerative diseases, and tumor progression. During the biogenesis of EVs, they encapsulate biologically active macromolecules (i.e., nucleotides and proteins) and transmit signals for delivering them to neighboring or cells that are located some distance away. In contrast, there are receptor molecules on the surface of EVs that function to mediate EV-to-cell and EV-to-matrix interactions. A growing body of evidence indicates that the EV surface is heavily modified with glycans, the function of which is to regulate the biogenesis and extracellular behaviors of EVs. In this chapter, we introduce the current status of our knowledge concerning EV glycosylation and discuss how it influences EV biology, highlighting the potential roles of EV glycans in clinical applications.

Peptide Sequence Mapping around Bisecting GlcNAc-Bearing N-Glycans in Mouse Brain.

N-glycosylation is essential for many biological processes in mammals. A variety of N-glycan structures exist, of which, the formation of bisecting N-acetylglucosamine (GlcNAc) is catalyzed by N-acetylglucosaminyltransferase-III (GnT-III, encoded by the Mgat3 gene). We previously identified various bisecting GlcNAc-modified proteins involved in Alzheimer's disease and cancer. However, the mechanisms by which GnT-III acts on the target proteins are unknown. Here, we performed comparative glycoproteomic analyses using brain membranes of wild type (WT) and Mgat3-deficient mice. Target glycoproteins of GnT-III were enriched with E4-phytohemagglutinin (PHA) lectin, which recognizes bisecting GlcNAc, and analyzed by liquid chromatograph-mass spectrometry. We identified 32 N-glycosylation sites (Asn-Xaa-Ser/Thr, Xaa ≠ Pro) that were modified with bisecting GlcNAc. Sequence alignment of identified N-glycosylation sites that displayed bisecting GlcNAc suggested that GnT-III does not recognize a specific primary amino acid sequence. The molecular modeling of GluA1 as one of the good cell surface substrates for GnT-III in the brain, indicated that GnT-III acts on N-glycosylation sites located in a highly flexible and mobile loop of GluA1. These results suggest that the action of GnT-III is partially affected by the tertiary structure of target proteins, which can accommodate bisecting GlcNAc that generates a bulky flipped-back conformation of the modified glycans.

Ganglioside GD2 Enhances the Malignant Phenotypes of Melanoma Cells by Cooperating with Integrins.

Gangliosides have been considered to modulate cell signals in the microdomain of the cell membrane, lipid/rafts, or glycolipid-enriched microdomain/rafts (GEM/rafts). In particular, cancer-associated gangliosides were reported to enhance the malignant properties of cancer cells. In fact, GD2-positive (GD2+) cells showed increased proliferation, invasion, and adhesion, compared with GD2-negative (GD2-) cells. However, the precise mechanisms by which gangliosides regulate cell signaling in GEM/rafts are not well understood. In order to analyze the roles of ganglioside GD2 in the malignant properties of melanoma cells, we searched for GD2-associating molecules on the cell membrane using the enzyme-mediated activation of radical sources combined with mass spectrometry, and integrin ß1 was identified as a representative GD2-associating molecule. Then, we showed the physical association of GD2 and integrin ß1 by immunoprecipitation/immunoblotting. Close localization was also shown by immuno-cytostaining and the proximity ligation assay. During cell adhesion, GD2+ cells showed multiple phospho-tyrosine bands, i.e., the epithelial growth factor receptor and focal adhesion kinase. The knockdown of integrin ß1 revealed that the increased malignant phenotypes in GD2+ cells were clearly cancelled. Furthermore, the phosphor-tyrosine bands detected during the adhesion of GD2+ cells almost completely disappeared after the knockdown of integrin ß1. Finally, immunoblotting to examine the intracellular distribution of integrins during cell adhesion revealed that large amounts of integrin ß1 were localized in GEM/raft fractions in GD2+ cells before and just after cell adhesion, with the majority being localized in the non-raft fractions in GD2- cells. All these results suggest that GD2 and integrin ß1 cooperate in GEM/rafts, leading to enhanced malignant phenotypes of melanomas.

Novel Molecular Mechanisms of Gangliosides in the Nervous System Elucidated by Genetic Engineering.

Acidic glycosphingolipids, i.e., gangliosides, are predominantly and consistently expressed in nervous tissues of vertebrates at high levels. Therefore, they are considered to be involved in the development and function of nervous systems. Recent studies involving genetic engineering of glycosyltransferase genes have revealed novel aspects of the roles of gangliosides in the regulation of nervous tissues. In this review, novel findings regarding ganglioside functions and their modes of action elucidated mainly by studies of gene knockout mice are summarized. In particular, the roles of gangliosides in the regulation of lipid rafts to maintain the integrity of nervous systems are reported with a focus on the roles in the regulation of neuro-inflammation and neurodegeneration via complement systems. In addition, recent advances in studies of congenital neurological disorders due to genetic mutations of ganglioside synthase genes and also in the techniques for the analysis of ganglioside functions are introduced.

New era of research on cancer-associated glycosphingolipids.

Cancer-associated glycosphingolipids have been used as markers for diagnosis and targets for immunotherapy of malignant tumors. Recent progress in the analysis of their implications in the malignant properties of cancer cells revealed that cancer-associated glycosphingolipids are not only tumor markers, but also functional molecules regulating various signals introduced by membrane microdomains, lipid rafts. In particular, a novel approach, enzyme-mediated activation of radical sources combined with mass spectrometry, has enabled us to clarify the mechanisms by which cancer-associated glycosphingolipids regulate cell signals based on the interaction with membrane molecules and formation of molecular complexes on the cell surface. Novel findings obtained from these approaches are now providing us with insights into the development of new anticancer therapies targeting membrane molecular complexes consisting of cancer-associated glycolipids and their associated membrane molecules. Thus, a new era of cancer-associated glycosphingolipids has now begun.

Elucidation of the enigma of glycosphingolipids in the regulation of inflammation and degeneration - Great progress over the last 70 years.

Since globotetraosylceramide was defined as a major glycosphingolipid in human erythrocytes, various glycolipids have been found in normal cells and diseased organs. However, the implications of their polymorphic structures in the function of individual cells and tissues have not been clarified. Genetic manipulation of glycosphingolipids in cultured cells and experimental animals has enabled us to substantially elucidate their roles. In fact, great progress has been achieved in the last 70 years in revealing that glycolipids are essential in the maintenance of integrity of nervous tissues and other organs. Furthermore, the correct composition of glycosphingolipids has been shown to be critical for the protection against inflammation and degeneration. Here, we summarized historic information and current knowledge about glycosphingolipids, with a focus on their involvement in inflammation and degeneration. This topic is significant for understanding the biological responses to various stresses, because glycosphingolipids play roles in the interaction with various intrinsic and extrinsic factors. These findings are also important for the application of therapeutic interventions of various diseases.

Oligosaccharyltransferase: A Gatekeeper of Health and Tumor Progression.

Oligosaccharyltransferase (OST) is a multi-span membrane protein complex that catalyzes the addition of glycans to selected Asn residues within nascent polypeptides in the lumen of the endoplasmic reticulum. This process, termed N-glycosylation, is a fundamental post-translational protein modification that is involved in the quality control, trafficking of proteins, signal transduction, and cell-to-cell communication. Given these crucial roles, N-glycosylation is essential for homeostasis at the systemic and cellular levels, and a deficiency in genes that encode for OST subunits often results in the development of complex genetic disorders. A growing body of evidence has also demonstrated that the expression of OST subunits is cell context-dependent and is frequently altered in malignant cells, thus contributing to tumor cell survival and proliferation. Importantly, a recently developed inhibitor of OST has revealed this enzyme as a potential target for the treatment of incurable drug-resistant tumors. This review summarizes our current knowledge regarding the functions of OST in the light of health and tumor progression, and discusses perspectives on the clinical relevance of inhibiting OST as a tumor treatment.

ASC amino acid transporter 2, defined by enzyme-mediated activation of radical sources, enhances malignancy of GD2-positive small-cell lung cancer.

Ganglioside GD2 is specifically expressed in small-cell lung cancer (SCLC) cells, leading to enhancement of malignant phenotypes, such as cell proliferation and migration. However, how GD2 promotes malignant phenotypes in SCLC cells is not well known. In this study, to reveal the mechanisms by which GD2 increases malignant phenotypes in SCLC cells, we used enzyme-mediated activation of radical sources combined with mass spectrometry in GD2+ SCLC cells. Consequently, we identified ASC amino acid transporter 2 (ASCT2), a major glutamine transporter, which coordinately works with GD2. We showed that ASCT2 was highly expressed in glycolipid-enriched microdomain/rafts in GD2+ SCLC cells, and colocalized with GD2 in both proximity ligation assay and immunocytostaining, and bound with GD2 in immunoprecipitation/TLC immunostaining. Malignant phenotypes of GD2+ SCLC cells were enhanced by glutamine uptake, and were suppressed by L-γ-glutamyl-p-nitroanilide, a specific inhibitor of ASCT2, through reduced phosphorylation of p70 S6K1 and S6. These results suggested that ASCT2 enhances glutamine uptake in glycolipid-enriched microdomain/rafts in GD2+ SCLC cells, leading to the enhancement of cell proliferation and migration through increased phosphorylation of the mTOR complex 1 signaling axis.

Neogenin, Defined as a GD3-associated Molecule by Enzyme-mediated Activation of Radical Sources, Confers Malignant Properties via Intracytoplasmic Domain in Melanoma Cells.

To investigate mechanisms for increased malignant properties in malignant melanomas by ganglioside GD3, enzyme-mediated activation of radical sources and subsequent mass spectrometry were performed using an anti-GD3 antibody and GD3-positive (GD3+) and GD3-negative (GD3-) melanoma cell lines. Neogenin, defined as a GD3-neighbored molecule, was largely localized in lipid/rafts in GD3+ cells. Silencing of neogenin resulted in the reduction of cell growth and invasion activity. Physical association between GD3 and neogenin was demonstrated by immunoblotting of the immunoprecipitates with anti-neogenin antibody from GD3+ cell lysates. The intracytoplasmic domain of neogenin (Ne-ICD) was detected in GD3+ cells at higher levels than in GD3- cells when cells were treated by a proteasome inhibitor but not when simultaneously treated with a γ-secretase inhibitor. Exogenous GD3 also induced increased Ne-ICD in GD3- cells. Overexpression of Ne-ICD in GD3- cells resulted in the increased cell growth and invasion activity, suggesting that Ne-ICD plays a role as a transcriptional factor to drive malignant properties of melanomas after cleavage with γ-secretase. γ-Secretase was found in lipid/rafts in GD3+ cells. Accordingly, immunocyto-staining revealed that GD3, neogenin, and γ-secretase were co-localized at the leading edge of GD3+ cells. All these results suggested that GD3 recruits γ-secretase to lipid/rafts, allowing efficient cleavage of neogenin. ChIP-sequencing was performed to identify candidates of target genes of Ne-ICD. Some of them actually showed increased expression after expression of Ne-ICD, probably exerting malignant phenotypes of melanomas under GD3 expression.

A therapeutic trial of human melanomas with combined small interfering RNAs targeting adaptor molecules p130Cas and paxillin activated under expression of ganglioside GD3.

We previously demonstrated that focal adhesion kinase (FAK), p130Cas and paxillin are crucially involved in the enhanced malignant properties under expression of ganglioside GD3 in melanoma cells. Therefore, molecules existing in the GD3-mediated signaling pathway could be considered as suitable targets for therapeutic intervention in malignant melanoma. The aim of this study was to determine whether blockade of p130Cas and/or paxillin by RNAi suppresses melanoma growth. We found a suitable dose (40 µM siRNA, 25 µl/tumor) of the siRNA to suppress p130Cas in the xenografts generated in nu/nu mice. Based on these results, we performed intratumoral (i.t.) treatment with anti-p130Cas and/or anti-paxillin siRNAs mixed with atelocollagen as a drug delivery system in a xenograft tumor of a human melanoma cell line, SK-MEL-28. Mixture of atelocollagen (1.75%) and an siRNA (500 or 1000 pmol/tumor) was injected into the tumors every 3 days after the first injection. An siRNA against human p130Cas markedly suppressed tumor growth of the xenograft in a dose-dependent manner, whereas siRNA against human paxillin slightly inhibited the tumor growth. A control siRNA against firefly luciferase showed no effect. To our surprise, siRNA against human p130Cas (500 or 1000 pmol/tumor) combined with siRNA against human paxillin dramatically suppressed tumor growth. In agreement with the tumor suppression effects of the anti-p130Cas siRNA, reduction in Ki-67 positive cell number as well as in p130Cas expression was demonstrated by immunohistostaining. These results suggested that blockade of GD3-mediated growth signaling pathways by siRNAs might be a novel and promising therapeutic strategy against malignant melanomas, provided signaling molecules such as p130Cas and paxillin are significantly expressed in individual cases. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.

Glycolipids: Essential regulator of neuro-inflammation, metabolism and gliomagenesis.

Gene knockout mice of glycosyltransferases have clearly showed roles of their products in the bodies, while there are examples where phenotype of knockout was much less severe than expected probably due to functional redundancy. The most striking novel finding obtained from ganglioside-deficient mice was that progressive inflammatory reaction took place, leading to neurodegeneration. In particular, dysfunction of complement-regulatory proteins due to deteriorated architecture of lipid rafts seemed to be essential mechanisms for the inflammation. Furthermore, roles of gangliosides in neurons were demonstrated by neuron-specific transgenic of B4galnt1 with genetic background of B4galnt1 deficiency. From study of gene knockout mice of St8sia1, new roles of b-series gangliosides in leptin secretion from adipocytes, and roles of a-series gangliosides in leptin receptor, ObR in hypothalamus were demonstrated, leading to apparent intact balance of energy. Essential roles of b-series gangliosides in malignant properties of gliomas were also shown, suggesting their roles in the regulation of inflammation and proliferation in nervous tissues. How to apply these findings for the control of newly discovered patients with ganglioside deficiency remains to be investigated. This article is part of a Special Issue entitled Neuro-glycoscience, edited by Kenji Kadomatsu and Hiroshi Kitagawa.