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PubMed2001

Molecular cloning and characterization of UDP-GlcNAc:lactosylceramide beta 1,3-N-acetylglucosaminyltransferase (beta 3Gn-T5), an essential enzyme for the expression of HNK-1 and Lewis X epitopes on glycolipids.

A new member of the UDP-N-acetylglucosamine:beta-galactose beta1,3-N-acetylglucosaminyltransferase (beta3Gn-T) family having the beta3Gn-T motifs was cloned from rat and human cDNA libraries and named beta3Gn-T5 based on its position in a phylogenetic tree. We concluded that beta3Gn-T5 is the most feasible candidate for lactotriaosylceramide (Lc(3)Cer) synthase, an important enzyme which plays a key role in the synthesis of lacto- or neolacto-series carbohydrate chains on glycolipids. beta3Gn-T5 exhibited strong activity to transfer GlcNAc to glycolipid substrates, such as lactosylceramide (LacCer) and neolactotetraosylceramide (nLc(4)Cer; paragloboside), resulting in the synthesis of Lc(3)Cer and neolactopentaosylceramide (nLc(5)Cer), respectively. A marked decrease in LacCer and increase in nLc(4)Cer was detected in Namalwa cells stably expressing beta3Gn-T5. This indicated that beta3Gn-T5 exerted activity to synthesize Lc(3)Cer and decrease LacCer, followed by conversion to nLc(4)Cer via endogenous galactosylation. The following four findings further supported that beta3Gn-T5 is Lc(3)Cer synthase. 1) The beta3Gn-T5 transcript levels in various cells were consistent with the activity levels of Lc(3)Cer synthase in those cells. 2) The beta3Gn-T5 transcript was presented in various tissues and cultured cells. 3) The beta3Gn-T5 expression was up-regulated by stimulation with retinoic acid and down-regulated with 12-O-tetradecanoylphorbol-13-acetate in HL-60 cells. 4) The changes in beta3Gn-T5 transcript levels during the rat brain development were determined. Points 2, 3, and 4 were consistent with the Lc(3)Cer synthase activity reported previously.

Amino Acid Sequence↗

PubMed1990

Dynamics and longevity of the glycolipid-anchored membrane protein, Thy-1.

Thy-1 and a number of other proteins are anchored to the outer hemi-leaflet of membranes by a glycolipid moiety containing ethanolamine phosphate, mannose, glucosamine, and phosphatidylinositol. They nevertheless have the striking property of being able to transduce signals across the plasma membrane. We here demonstrate, for the BW5147 murine T lymphoma, that (a) greater than 90% of Thy-1 is at the cell surface, (b) Thy-1 is about one order of magnitude less concentrated in coated pits than the transferrin receptor or H-2 antigens, (c) Thy-1 undergoes at most very limited endocytosis or diacytosis, and (d) Thy-1 has an unusually slow turnover rate. Several similar observations have also been made for a second glycolipid-anchored protein, the T cell activating protein. Thus, the absence of cytoplasmic and trans-membrane domains may result in lipid-anchored proteins being confined to the cell surface and being free from constraints which affect the turnover of transmembrane proteins.

Animals↗

PubMed1993

Carbohydrate recognition in the peripheral nervous system: a calcium-dependent membrane binding site for HNK-1 reactive glycolipids potentially involved in Schwann cell adhesion.

The carbohydrate determinants recognized by the HNK-1 antibody are potential cell-cell recognition ligands in the peripheral nervous system (PNS). The HNK-1 reactive sulfoglucuronylneolacto (SGNL) glycolipids specifically support Schwann cell adhesion, suggesting the presence of a cell surface receptor specific for SGNL-oligosaccharides. We directly probed PNS membranes for receptors complementary to SGNL determinants using a synthetic radioligand consisting of radioiodinated serum albumin derivatized with multiple SGNL-oligosaccharides. A high-affinity, saturable, calcium-dependent binding site for this ligand was found in PNS myelin membranes. Binding activity was carbohydrate-specific (most potently inhibited by SGNL-lipids compared to other glycolipids) and PNS-specific (absent from comparable central nervous system membranes). The SGNL-specific binding activity on PNS membranes reported here may be involved in peripheral myelination or myelin stabilization.

Animals↗

PubMed1994

A glycolipid-anchored prion protein is endocytosed via clathrin-coated pits.

The cellular prion protein (PrPc) is a glycolipid-anchored, cell surface protein of unknown function, a posttranslationally modified isoform of which PrPSc is involved in the pathogenesis of Creutzfeldt-Jakob disease, scrapie, and other spongiform encephalopathies. We have shown previously that chPrP, a chicken homologue of mammalian PrPC, constitutively cycles between the cell surface and an endocytic compartment, with a transit time of approximately 60 min in cultured neuroblastoma cells. We now report that endocytosis of chPrP is mediated by clathrin-coated pits. Immunogold labeling of neuroblastoma cells demonstrates that the concentration of chPrP within 0.05 microns of coated pits is 3-5 times higher than over other areas of the plasma membrane. Moreover, gold particles can be seen within coated vesicles and deeply invaginated coated pits that are in the process of pinching off from the plasma membrane. ChPrP is also localized to coated pits in primary cultures of neurons and glia, and is found in coated vesicles purified from chicken brain. Finally, internalization of chPrP is reduced by 70% after neuroblastoma cells are incubated in hypertonic medium, a treatment that inhibits endocytosis by disrupting clathrin lattices. Caveolae, plasmalemmal invaginations in which several other glycolipid-anchored proteins are concentrated, are not seen in neuroblastoma cells analyzed by thin-section or deep-etch electron microscopy. Moreover, these cells do not express detectable levels of caveolin, a caveolar coat protein. Since chPrP lacks a cytoplasmic domain that could interact directly with the intracellular components of clathrin-coated pits, we propose that the polypeptide chain of chPrP associates with the extracellular domain of a transmembrane protein that contains a coated pit internalization signal.

Animals↗

PubMed1979

Capping of exogenous Forssman glycolipid on cells.

When motile cells are incubated with Forssman glycolipid, the antigen is incorporated into the cells' plasma membranes. If cross-linked by antibody, the patched glycolipids cap. This process is sensitive to those drugs that are known to inhibit capping of protein antigens. The results support a flow mechanism for capping.

Animals↗

PubMed1980

Myelin-specific proteins and glycolipids in rat Schwann cells and oligodendrocytes in culture.

We have used antibodies to identify Schwann cells and oligodendrocytes and to study the expression of myelin-specific glycolipids and proteins in these cells isolated from perinatal rats. Our findings suggest that only Schwann cells which have been induced to myelinate make detectable amounts of galactocerebroside (GC), sulfatide, myelin basic protein (BP), or the major peripheral myelin glycoprotein (P0). When rat Schwann cells were cultured, they stopped making detectable amounts of these myelin molecules, even when the cells were associated with neurites in short-term explant cultures of dorsal root ganglion. In contrast, oligodendrocytes in dissociated cell cultures of neonatal optic nerve, corpus callosum, or cerebellum continued to make GC, sulfatide and BP for many weeks, even in the absence of neurons. These findings suggest that while rat Schwann cells require a continuing signal from appropriate axons to make detectable amounts of myelin-specific glycolipids and proteins, oligodendrocytes do not. Schwann cells and oligodendrocytes also displayed very different morphologies in vitro which appeared to reflect their known differences in myelinating properties in vivo. Since these characteristic morphologies are maintained when Schwann cells and oligodendrocytes were grown together in mixed cultures and in the absence of neurons, we concluded that they are intrinsic properties of these two different myelin-forming cells.

Aging↗

PubMed2000

CD1b-mediated T cell recognition of a glycolipid antigen generated from mycobacterial lipid and host carbohydrate during infection.

T cells recognize microbial glycolipids presented by CD1 proteins, but there is no information regarding the generation of natural glycolipid antigens within infected tissues. Therefore, we determined the molecular basis of CD1b-restricted T cell recognition of mycobacterial glycosylated mycolates, including those produced during tissue infection in vivo. Transfection of the T cell receptor (TCR) alpha and beta chains from a glucose monomycolate (GMM)-specific T cell line reconstituted GMM recognition in TCR-deficient T lymphoblastoma cells. This TCR-mediated response was highly specific for natural mycobacterial glucose-6-O-(2R, 3R) monomycolate, including the precise structure of the glucose moiety, the stereochemistry of the mycolate lipid, and the linkage between the carbohydrate and the lipid. Mycobacterial production of antigenic GMM absolutely required a nonmycobacterial source of glucose that could be supplied by adding glucose to media at concentrations found in mammalian tissues or by infecting tissue in vivo. These results indicate that mycobacteria synthesized antigenic GMM by coupling mycobacterial mycolates to host-derived glucose. Specific T cell recognition of an epitope formed by interaction of host and pathogen biosynthetic pathways provides a mechanism for immune response to those pathogenic mycobacteria that have productively infected tissues, as distinguished from ubiquitous, but innocuous, environmental mycobacteria.

Animals↗

PubMed2003

A monoclonal antibody to a carbohydrate epitope expressed on glycolipid and on alpha3beta1 integrin on human esophageal carcinoma.

A mouse monoclonal antibody (MAb-9) produced by immunization with a human esophageal carcinoma cell line, TE-2 (derived from undifferentiated squamous cell carcinoma) reacted specifically with about 30% of esophageal carcinoma cell lines and tissue sections from clinical samples. MAb-9 showed minimal reactivity with normal esophageal tissue. (125)I, fluorescent or gold particle labeled MAb-9 bound to TE-2 cell surfaces. (125)I-radiolabeled MAb-9 was used to detect reactive material from cell extracts in Western blot. Treatment of TE-2 membrane proteins with neuraminidase, N-glycanase or O-glycanase reduced antigen detection. Treatment of cells with periodic acid destroyed antibody binding in ELISA. Lipid extracts from cell membranes, containing glycolipids, also reacted with MAb-9. MAb-9 was used to purify target antigen from detergent solubilized membrane proteins and the prominent bands from subsequent gel electrophoresis were trypsin digested and analyzed by mass spectrometry. Peptides from alpha(3) and beta(1) integrin chains were identified. These data indicate that alpha3beta1integrin is prominently expressed on certain esophageal carcinomas and that a specific carbohydrate unit is selectively displayed on the alpha(3) integrin subunit as well as on glycolipid on the cell surface. The alpha3beta1 integrin expressed on A-431 carcinoma cells does not display this carbohydrate epitope and is not detected by MAb-9. Thus, expression of the carbohydrate epitope is the basis for the tumor selective reaction of MAb-9 with a subset of esophageal carcinomas.

Animals↗

PubMed2006

GPI-anchored proteins and free GPI glycolipids of procyclic form Trypanosoma brucei are nonessential for growth, are required for colonization of the tsetse fly, and are not the only components of the surface coat.

The procyclic form of Trypanosoma brucei exists in the midgut of the tsetse fly. The current model of its surface glycocalyx is an array of rod-like procyclin glycoproteins with glycosylphosphatidylinositol (GPI) anchors carrying sialylated poly-N-acetyllactosamine side chains interspersed with smaller sialylated poly-N-acetyllactosamine-containing free GPI glycolipids. Mutants for TbGPI12, deficient in the second step of GPI biosynthesis, were devoid of cell surface procyclins and poly-N-acetyllactosamine-containing free GPI glycolipids. This major disruption to their surface architecture severely impaired their ability to colonize tsetse fly midguts but, surprisingly, had no effect on their morphology and growth characteristics in vitro. Transmission electron microscopy showed that the mutants retained a cell surface glycocalyx. This structure, and the viability of the mutants in vitro, prompted us to look for non-GPI-anchored parasite molecules and/or the adsorption of serum components. Neither were apparent from cell surface biotinylation experiments but [3H]glucosamine biosynthetic labeling revealed a group of previously unidentified high apparent molecular weight glycoconjugates that might contribute to the surface coat. While characterizing GlcNAc-PI that accumulates in the TbGPI12 mutant, we observed inositolphosphoceramides for the first time in this organism.

Acetylglucosamine↗

PubMed1995

Guillain-Barré syndrome in northern China. Relationship to Campylobacter jejuni infection and anti-glycolipid antibodies.

Guillain-Barré syndrome has been considered to be primarily an acute inflammatory demyelinating polyneuropathy (AIDP). Our experience with Guillain-Barré syndrome in northern China differs from the traditional concept. Electrophysiologically and pathologically, most of our patients have motor axonal degeneration with minimal cellular inflammation, which we have termed 'acute motor axonal neuropathy' (AMAN). The current studies were undertaken to characterize prospectively the clinical, electrophysiological, and serological features of Guillain-Barré syndrome, defined clinically, in northern China. In 1991 and 1992, we characterized by electrodiagnostic criteria 129 Chinese patients with Guillain-Barré syndrome. The AMAN form was present in 65% of patients, the AIDP form in 24% and 11% were unclassifiable. For the 38 patients who presented from January to October, 1992, we performed serological assays for antibodies to Campylobacter jejuni and to glycolipids. Of these 38 patients, 55% had AMAN, 32% had AIDP and 13% were unclassifiable. Sixty-six percent of the 38 had serological evidence of recent C. jejuni infection as compared with 16% of village controls (P = 0.001). Seventy-six percent of AMAN patients and 42% of AIDP patients were seropositive. IgG anti-GM1 antibodies were more frequent in Guillain-Barré syndrome patients compared with village controls (42% versus 6%; P < 0.01). However, no statistically significant correlations were found between the pattern of disease, AMAN or AIDP, anti-glycolipid antibodies, or C. jejuni antibodies. Based on electrophysiological criteria, Guillain-Barré syndrome in northern China can be divided into two predominant forms: AIDP and AMAN. The AMAN form is more common and predominates in the yearly summer outbreaks of Guillain-Barré syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2005

Murine glycosyltransferases responsible for the expression of globo-series glycolipids: cDNA structures, mRNA expression, and distribution of their products.

Biological functions of globo-series glycosphingolipids are not well understood. In this study, murine cDNAs of two glycosyltransferases responsible for the synthesis of globo-series glycolipids and mRNA expression of those genes were analyzed. Distribution of their products was also analyzed. Murine cDNAs for Gb3/CD77 synthase and Gb4 synthase predicted that both of them are type II membrane proteins with 348 and 331 amino acids, respectively. In northern blotting, Gb3/CD77 synthase gene was mainly expressed in kidney and lung but also detected in many other tissues. Gb4 synthase was expressed in brain, heart, kidney, liver, skin, and testis. In the immunohistological analysis, Gb3/CD77 was mainly expressed in the proximal tubules as revealed with coincidental expression with angiotensin-converting enzyme (ACE). In spleen, it was detected in pre-B cells in the peripheral region of the white pulp, as suggested with coincidental expression with CD10. It was also expressed on the endothelia of the alveolar capillaries in lung and on the sebaceous ducts aside of the hair follicles. Gb4 was also detected mainly on the proximal tubules in kidney and on the endothelia of the alveolar capillaries in lung as Gb3/CD77. But it was also detected on the epithelium of the bronchus, seminiferous tubules and tails of spermatozoa in testis, blood vessels of choroids plexus and endothelial cells in brain, and central and hepatoportal veins in liver. The expression patterns of two genes and their products almost corresponded with some exception. The results would provide essential information for the functional studies of globo-series glycolipids.

Amino Acid Sequence↗

PubMed1977

Cross-protective immunity to Gram-negative bacilli: studies with core glycolipid of Salmonella minnesota and antigens of Streptococcus pneumoniae.

Two immunoprophylactic approaches to the control of infections caused by gramnegative bacilli were evaluated by study of experimental infections in animals. The core glycolipid antigen derived from the Re mutant of Salmonella minnesota R595 is shared by virtually all enteric bacteria, and immunization with this endotoxin protects against the hemodynamic sequelae of bacterial infection and pyrexia without enhancing intravascular clearance of bacteria. The degree of protection afforded by active and passive immunization with core glycolipid was significantly less than that conferred by type-specific immunization. Escherichia coli and Klebsiella pneumoniae share capsular antigens with some strains of Streptococcus pneumoniae; by the mechanism of enhanced opsonization, antibodies to S. pneumoniae may cross-protect against infection with E. coli or K. pneumoniae.

Animals↗

PubMed1992

Human monoclonal antibodies to glycolipid A that exhibit complement species-specific effector functions.

Two human IgM monoclonal anti-glycolipid A antibodies (MAbs) were evaluated for their abilities to bind to various endotoxins and pathogenic gram-negative bacteria and to activate complement pathways, thereby accomplishing bactericidal and opsonic effector functions. Both MAbs cross-reacted with glycolipid A mutant lipopolysaccharides from rough colony-forming gram-negative bacteria and with selected endotoxins from smooth colony-forming bacteria. However, MAb 10235 bound to all clinical isolates of Escherichia coli and Klebsiella pneumoniae tested but only very weakly to Pseudomonas aeruginosa, whereas MAb 10058 bound to all three genera. Several strains of serum-insensitive organisms were selected for evaluation of antigen-specific, complement-mediated effector functions for the two MAbs. Assessment of bactericidal and opsonic activities showed that neither MAb was able to activate complement from nonprimate species (mouse, rat, rabbit, guinea pig, or sheep). However, both MAbs were highly effective in using primate sources of serum complement to mediate these effector functions.

Animals↗

PubMed1994

Pathogenesis of Shigella diarrhea: XVII. A mammalian cell membrane glycolipid, Gb3, is required but not sufficient to confer sensitivity to Shiga toxin.

Shiga toxin recognizes a galactose-alpha 1-->4-galactose terminal glycolipid, globotriaosylceramide (Gb3), in sensitive mammalian cells and is translocated by endocytosis to the cytoplasm, where it blocks protein synthesis. To determine if Gb3 is both required and sufficient for toxicity, Gb3 content in cells was altered by blocking key biosynthetic or degradative path enzymes with specific inhibitors. The resulting decrease or increase in cellular Gb3 was associated with a decrease or increase in binding of and response to Shiga toxin. Toxin-resistant Gb3-deficient variants of sensitive cells fused with liposomes containing Gb3 but not globotetraosylceramide (Gb4) became susceptible, whereas fusion of Gb3 liposomes to naturally resistant Gb3-deficient CHO cells increased toxin binding but not cytotoxicity. These data demonstrate that Gb3 is required, but not sufficient, for the action of Shiga toxin and suggest the existence of a toxin translocation mechanism linked to surface glycolipids that is not expressed in CHO cells.

Animals↗

PubMed1979

Effect of butyrate on glycolipid metabolism of two cell types of rat ascites hepatomas with different ganglioside biosynthesis.

The effect of butyrate on glycolipid metabolism and morphological differentiation in the cell culture system of rat ascites hepatomas, AH 7974 of island-forming type and AH 7974F of free type, was studied. Both cell lines adhered to the substratum in the presence of 1 mM butyrate. In the case of AH 7974, the addition of butyrate induced a distinct morphological change but the other cell line showed no such conspicuous change. Butyrate-treated AH 7974 cells showed a 2 to 3-fold elevation of CMP-N-acetylneuraminic acid: lactosylceramide sialyltransferase activity to form N-acetylneuraminylgalactosylglucosylceramide (GM3). On the other hand, no enzyme activity could be detected in AH 7974F cells. Four glycosyltransferase activities involved in glycolipid synthesis, including sialyltransferase in AH 7974F cells, were reduced by butyrate. From these observations we concluded that sialyltransferase to form GM3, or TM3 itself, is prerequisite for the morphological alteration induced by butyrate.

Animals↗

PubMed1982

Simple purification method for anti-glycolipid antibody using polystyrene latex beads coated with gangliotetraosylceramide.

A simple method for the purification of antiglycolipid antibody is described. Polystyrene latex beads coated with gangliotetraosylceramide (GA1) were used as immunoadsorbent for the purification of anti-GA1 antibody. The antibody bound to the GA1-coated latex beads was released with 1 M NaSCN solution. The glycolipid-coated latex beads seem valuable not only for the purification of antibodies but also as a tool for investigating the function of glycolipids.

Antibodies↗

PubMed1984

Acidic glycolipids from kidney of suncus (Insectivora).

Lipids were extracted from the kidney of house musk shrew (Suncus murinus), which belongs to the order Insectivora. Acidic glycosphingolipids were purified from lipid extracts by mild alkaline methanolysis followed by column chromatographies on DEAE-Sephadex and silica beads (Iatrobeads). Purified glycolipids were analyzed by thin-layer chromatography, mild acid hydrolysis, gas liquid chromatography of the methyl glycosides after methanolysis and gas chromatography-mass spectrometry of the partially methylated alditol acetates. The kidney of suncus was unique in that it contained ganglioside GM2 (NeuAc type, 28.7 nmol and NeuGc type, 15.8 nmol/g tissue) as the major ganglioside. GM4 (NeuAc) (2.6 nmol/g), and GM3 (NeuAc type, 11.5 nmol and NeuGc type, 8.7 nmol/g) were also present. The content (298.9 nmol/g) of galactosyl sulfatide (GalCer-I3-sulfate) was higher than the values reported previously for other animal species. The total amount of acidic groups in glycolipids of suncus kidney was compared with the values for the kidney of 4 placental mammals to obtain an allometric correlation: log Y = 0.266 + 0.780 log X where X designates body weight, kg and Y, total acidic groups, mumol. A highly significant correlation (r = 0.999) was obtained among values from 5 representative placental mammals which live in mesic environments, suggesting that acidic glycosphingolipids are essential for the kidney function.

Animals↗

PubMed1985

Acidic glycolipids from dolphin kidney.

The composition and contents of acidic glycolipids in the kidney of a striped dolphin (Stenella coeruleoalba, the order Cetacea, whales) were determined. The following eight acidic glycolipids were isolated and characterized: SM4s (124.2 nmol/g tissue), SM3 (8.7), GM3 (NeuAc) (12.3), GM3 (NeuGc) (31.6), GD3 (NeuAc-NeuAc) (14.7), GD3 (NeuAc-NeuGc) (II3 alpha(NeuAc alpha 2-8NeuGc)-LacCer) (9.8), GD3 (NeuGc-NeuAc) (II3 alpha(NeuGc alpha 2-8NeuAc)-LacCer) (5.3), and GD3 (NeuGc-NeuGc) (15.8). The assignment of the four types of GD3 was further confirmed as described below. Evidence indicating 2-8 linkages of the disialosyl residues of GD3 was obtained on methylation analysis of sialic acid. GD3 (NeuAc-NeuAc) and GD3 (NeuGc-NeuAc) were degraded to GM3 (NeuAc), and GD3 (NeuAc-NeuGc) and GD3 (NeuGc-NeuGc) yielded GM3 (NeuGc) on mild acid hydrolysis. Fragment ions characteristic of the carbohydrate and lipophilic moieties of the permethylated GD3 were observed in direct inlet-electron impact-mass spectra. The presence of these four types of GD3 in a tissue has not been reported previously. GD3 contained non-hydroxy (69-84%) and hydroxy fatty acids (16-31%) with 16-24 carbons. The long chain base of all GD3, except GD3 (NeuGc-NeuAc) (not analyzed), consisted of 4-sphingenine (d18:1) and 4-hydroxysphinganine (t18:0) in almost equal amounts. The total amount of renal lipid-bound acidic groups (sulfate and sialic acid) of the dolphin (190 mumol/animal) is considerably higher than that of a terrestrial mammal (88 mumol/animal) with a body weight comparable to that of the dolphin. This deviation suggests that the amount of renal acidic amphiphiles required to maintain the osmotic balance of body fluids in marine mammals might be higher than that in terrestrial ones.

Animals↗