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PubMed1982

Effects of structural variations in synthetic glycolipids upon mitogenicity for spleen lymphocytes, adjuvancy for humoral immune response and on anti-tumour potential.

Synthetic glycolipids prepared by esterification of various sugars and sorbitol, and containing various numbers of saturated or unsaturated fatty acid residues as well as bacterial lipid A and lipopolysaccharide, were tested for mitogenicity of splenic cells of Fischer rats and Swiss mice and for the augmentation of humoral immune response against sheep red blood cells in these species. Subsequently a few of the humoral immune-response-enhancing glycolipids were compared with non-enhancers in their anti-tumour activity against 13762 rat mammary carcinoma in inbred Fischer 344 rats and Ehrlich tumour in Swiss mice. They were given systemically after tumour inoculation and intratumourally in squalene and Tween emulsion after intradermal MAC tumour development. It was observed that certain structural characteristics in glycolipids with respect to the type of sugar, the type and number of fatty-acid residues were needed for their adjuvant action of the humoral arm of the immune response. Although humoral immune-response enhancers were somewhat superior to non-enhancers in their anti-tumour activity, the correlation coefficient demonstrated a lack of significant concordance. It is concluded that glycolipids selected for their ability to augment humoral immune responses against standard antigens need not be suspect as tumour-enhancers on the grounds that they would elicit blocking antibodies in vivo against tumour-associated antigens.

Adenocarcinoma↗
PubMed2000

Unique poly(glycerophosphate) lipoteichoic acid and the glycolipids of a Streptococcus sp. closely related to Streptococcus pneumoniae.

The Streptococcus sp. studied here is closely related to Streptococcus pneumoniae with 98.6% 16S rRNA similarity and 65% DNA/DNA homology. We isolated the lipoteichoic acid and the membrane glycolipids whose structures were established using conventional procedures and NMR spectroscopy. The lipoteichoic acid contains a linear 1,3-linked poly(glycerophosphate) chain which is partly substituted with D-alanine ester and is phosphodiester-linked to O6 of beta-D-Galf(1-->3)acyl2Gro. This lipoteichoic acid is the first example in which a monohexosylglycerol serves as the glycolipid anchor; and with an average chain length of 10 glycerophosphate residues it is the shortest known to date. MS analysis, applied for the first time to a native acylated lipoteichoic acid, revealed a continuous increase in chain length from seven to 17 glycerophosphate residues with a maximum at 10, and allowed identification of the fatty acid combinations. Membrane glycolipids consisted of beta-D-Galf(1-->3)acyl2Gro (9%), alpha-D-Glcp(1-->3)acyl2Gro (22%), alpha-D-Galp(1-->2)-alpha-D-Glcp(1-->3)acyl2Gro (64%) and alpha-D-Galp(1-->2)-(6-O-acyl)-alpha-D-Glcp(1-->3)acyl2Gro (5%). It is noteworthy that in lipoteichoic acid biosynthesis, Galfacyl2Gro, a less abundant membrane glycolipid, is selected as the lipid anchor. Despite the genetic relatedness to Streptococcus pneumoniae, the lipoteichoic acid structure is quite different to the complex structure of pneumococcal lipoteichoic acid [T. Behr et al. (1992) Eur. J. Biochem. 207, 1063-1075], thus providing an example that minor differences in DNA sequence exert major changes in macromolecular structure.

Chromatography, High Pressure Liquid↗
PubMed2006

Glycolipid alpha-C-galactosylceramide is a distinct inducer of dendritic cell function during innate and adaptive immune responses of mice.

alpha-Galactosylceramide (alpha-GalCer) is the prototype compound for studying the presentation of glycolipids on CD1d molecules to natural killer T (NKT) lymphocytes. A single i.v. dose of glycolipid triggers a cascade of events involving the production of several cytokines over the course of a day, a short-lived activation of NKT and natural killer (NK) cells, and a more prolonged adaptive T cell immune response if certain antigens are given together with alpha-GalCer. We find that a recently described analogue, alpha-C-galactosylceramide (alpha-C-GalCer), more potently induces these innate and adaptive immune responses in mice. alpha-C-GalCer acts as a more effective trigger for IL-12 and IFN-gamma production, although it minimally elicits IL-4 and TNF-alpha release into the serum. Also, alpha-C-GalCer better mobilizes NKT and natural killer cells to resist B16 melanoma. To help understand these effects, we find that alpha-C-GalCer binds more stably to dendritic cells than alpha-GalCer and that dendritic cells loaded with alpha-C-GalCer induce larger and more long lasting NKT cell responses in vivo. When glycolipid is targeted to dendritic cells in spleen together with antigens in dying cells, such as irradiated tumor cells, alpha-C-GalCer is active as an adjuvant for T cell-mediated immunity at lower doses, just 20 ng per mouse, where it is also able to up-regulate the required CD40L costimulatory molecule on NKT cells. Therefore, alpha-C-GalCer represents a glycolipid that binds more stably to dendritic cells and acts as a more effective link between innate and adaptive immunity in vivo.

Animals↗
PubMed1988

Glycolipid reanchoring of T-lymphocyte surface antigen CD8 using the 3' end sequence of decay-accelerating factor's mRNA.

Decay-accelerating factor (DAF) is one of a family of cell-associated proteins that undergo posttranslational modifications in which glycolipid anchoring structures are substituted for membrane-spanning sequences. The signals that direct the covalent substitution reaction in these proteins are unknown. Human DAF was expressed in Chinese hamster ovary (CHO) cells and murine BW lymphocytes. In both cases, the xenogeneic DAF in transfectants incorporated a glycolipid anchor. A chimeric CD8-DAF cDNA, encompassing the extra-cellular region of the T-lymphocyte surface antigen CD8 and the 3' end of DAF mRNA (encoding the C-terminal region of mature DAF as well as the hydrophobic extension peptide), was expressed in human leukemia lines after transfection with an Epstein-Barr virus-based episomal vector. The chimeric protein in transfectants demonstrated glycolipid anchoring, whereas unaltered CD8 in control experiments did not. The signals directing glycolipid anchoring in eukaryotic cells are thus evolutionarily conserved and contained in the 3' end of the DAF sequence.

Animals↗
PubMed1999

The proteoglycan lectin domain binds sulfated cell surface glycolipids and promotes cell adhesion.

The lecticans are a group of chondroitin sulfate proteoglycans characterized by the presence of C-type lectin domains. Despite the suggestion that their lectin domains interact with carbohydrate ligands, the identity of such ligands has not been elucidated. We previously showed that brevican, a nervous system-specific lectican, binds the surface of B28 glial cells (Yamada, H., Fredette, B., Shitara, K., Hagihara, K., Miura, R., Ranscht, B., Stallcup, W. B., and Yamaguchi, Y. (1997) J. Neurosci. 17, 7784-7795). In this paper, we demonstrate that two classes of sulfated glycolipids, sulfatides and HNK-1-reactive sulfoglucuronylglycolipids (SGGLs), act as cell surface receptors for brevican. The lectin domain of brevican binds sulfatides and SGGLs in a calcium-dependent manner as expected of a C-type lectin domain. Intact, full-length brevican also binds both sulfatides and SGGLs. The lectin domain immobilized as a substrate supports adhesion of cells expressing SGGLs or sulfatides, which was inhibited by monoclonal antibodies against these glycolipids or by treatment of the substrate with SGGLs or sulfatides. Our findings demonstrate that the interaction between the lectin domains of lecticans and sulfated glycolipids comprises a novel cell substrate recognition system, and suggest that lecticans in extracellular matrices serve as substrate for adhesion and migration of cells expressing these glycolipids in vivo.

Animals↗
PubMed2002

The Drosophila melanogaster brainiac protein is a glycolipid-specific beta 1,3N-acetylglucosaminyltransferase.

Mutations at the Drosophila melanogaster brainiac locus lead to defective formation of the follicular epithelium during oogenesis and to neural hyperplasia. The brainiac gene encodes a type II transmembrane protein structurally similar to mammalian beta1,3-glycosyltransferases. We have cloned the brainiac gene from D. melanogaster genomic DNA and expressed it as a FLAG-tagged recombinant protein in Sf9 insect cells. Glycosyltransferase assays showed that brainiac is capable of transferring N-acetylglucosamine (GlcNAc) to beta-linked mannose (Man), with a marked preference for the disaccharide Man(beta1,4)Glc, the core of arthro-series glycolipids. The activity of brainiac toward arthro-series glycolipids was confirmed by showing that the enzyme efficiently utilized glycolipids from insects as acceptors whereas it did not with glycolipids from mammalian cells. Methylation analysis of the brainiac reaction product revealed a beta1,3 linkage between GlcNAc and Man, proving that brainiac is a beta1,3GlcNAc-transferase. Human beta1,3GlcNAc-transferases structurally related to brainiac were unable to transfer GlcNAc to Man(beta1,4)Glc-based acceptor substrates and failed to rescue a homozygous lethal brainiac allele, indicating that these proteins are paralogous and not orthologous to brainiac.

Acetylglucosamine↗
PubMed2001

Cloning of a mouse beta 1,3 N-acetylglucosaminyltransferase GlcNAc(beta 1,3)Gal(beta 1,4)Glc-ceramide synthase gene encoding the key regulator of lacto-series glycolipid biosynthesis.

The distinction between the different classes of glycolipids is conditioned by the action of specific core transferases. The entry point for lacto-series glycolipids is catalyzed by the beta1,3 N-acetylglucosaminyltransferase GlcNAc(beta1,3)Gal(beta1,4)Glc-ceramide (Lc3) synthase enzyme. The Lc3 synthase activity has been shown to be regulated during development, especially during brain morphogenesis. Here, we report the molecular cloning of a mouse gene encoding an Lc3 synthase enzyme. The mouse cDNA included an open reading frame of 1131 base pairs encoding a protein of 376 amino acids. The Lc3 synthase protein shared several structural motifs previously identified in the members of the beta1,3 glycosyltransferase superfamily. The Lc3 synthase enzyme efficiently utilized the lactosyl ceramide glycolipid acceptor. The identity of the reaction products of Lc3 synthase-transfected CHOP2/1 cells was confirmed by thin-layer chromatography immunostaining using antibodies TE-8 and 1B2 that recognize Lc3 and Gal(beta1,4)GlcNAc(beta1,3)Gal(beta1,4)Glc-ceramide (nLc4) structures, respectively. In addition to the initiating activity for lacto-chain synthesis, the Lc3 synthase could extend the terminal N-acetyllactosamine unit of nLc4 and also had a broad specificity for gangliosides GA1, GM1, and GD1b to generate neolacto-ganglio hybrid structures. The mouse Lc3 synthase gene was mainly expressed during embryonic development. In situ hybridization analysis revealed that that the Lc3 synthase was expressed in most tissues at embryonic day 11 with elevated expression in the developing central nervous system. Postnatally, the expression was restricted to splenic B-cells, the placenta, and cerebellar Purkinje cells where it colocalized with HNK-1 reactivity. These data support a key role for the Lc3 synthase in regulating neolacto-series glycolipid synthesis during embryonic development.

Amino Acid Motifs↗
PubMedDate not supplied

New synthetic glycolipids for targeted gene transfer: synthesis, formulation in lipoplexes and specific interaction with lectin.

Nonviral gene delivery systems are a promising approach for gene therapy applications, despite their low in vivo gene transfer efficiency. One approach to enhance this efficiency is to incorporate targeting elements into cationic lipid/DNA complexes (lipoplexes). Ligand-containing lipoplexes have to retain their efficiency while exposing accessible ligand on their surface. Physicochemical properties (particle size, surface charge, and efficacy of DNA complexation) of the lipoplexes largely determine their gene transfer efficiency. We synthesized glycolipids with various galactosylated head ligand and incorporated them into lipoplexes. We showed that incorporation of up to 33% mol of glycolipid did not change the physicochemical properties of lipoplexes. Some of our glycolipids yielded lipoplexes whose galactosyl heads were well exposed on the surface as demonstrated by a strong interaction with Ricinus communis agglutinin. Glycolipid-containing lipoplexes gave an efficient gene transfer on hepatocytes, although no ligand-targeted transfection could be observed.

Cell Line, Tumor↗
PubMed1970

Synthesis of glycoprotein, glycolipid, protein, and lipid in synchronized L5178Y cells.

Synthesis of four macromolecular classes found in membranes-glycoprotein, glycolipid, protein, and lipid-was measured as a function of time of the cell cycle in synchronized L5178Y cells. Incorporation of leucine, choline, fucose, glucosamine, or thymidine into the cells, protein, nucleic acid, or lipid was measured by pulse-labeling for (1/2) hr at (1/2) hr intervals after release from the mitotic block. The amount of protein, lipid, glycoprotein, or glycolipid released or secreted into the medium by the L5178Y cells was also measured as a function of time of the cell cycle. Cellular protein was found to be synthesized throughout the cell cycle, with the highest synthesis occurring in the S period; synthesis was depressed in the M period. Cellular glycoprotein was synthesized at approximately the same times as protein, except that the rates of glycoprotein synthesis in the S period relative to other periods were much greater than for protein. Secreted protein was synthesized throughout the cell cycle without any general pattern, except that secretion was elevated in the late S and G(2) periods. Secreted glycoprotein was similar to secreted protein. Cellular lipid and cellular glycolipid were synthesized almost exclusively in the G(2) and M periods; there was no synthesis in the G(1) and S periods. Release or secretion of glycolipid and lipid also occurred in the G(2) and M periods.

Animals↗
PubMed1998

CD1d-restricted recognition of synthetic glycolipid antigens by human natural killer T cells.

A conserved subset of mature circulating T cells in humans expresses an invariant Valpha24-JalphaQ T cell receptor (TCR)-alpha chain rearrangement and several natural killer (NK) locus-encoded C-type lectins. These human T cells appear to be precise homologues of the subset of NK1.1(+) TCR-alpha/beta+ T cells, often referred to as NK T cells, which was initially identified in mice. Here we show that human NK T cell clones are strongly and specifically activated by the same synthetic glycolipid antigens as have been shown recently to stimulate murine NK T cells. Responses of human NK T cells to these synthetic glycolipids, consisting of certain alpha-anomeric sugars conjugated to an acylated phytosphingosine base, required presentation by antigen-presenting cells expressing the major histocompatibility complex class I-like CD1d protein. Presentation of synthetic glycolipid antigens to human NK T cells required internalization of the glycolipids by the antigen-presenting cell and normal endosomal targeting of CD1d. Recognition of these compounds by human NK T cells triggered proliferation, cytokine release, and cytotoxic activity. These results demonstrate a striking parallel in the specificity of NK T cells in humans and mice, thus providing further insight into the potential mechanisms of immune recognition by NK T cells and the immunological function of this unique T cell subset.

Animals↗
PubMedDate not supplied

Reactivity of antibodies to core glycolipid with gram-negative bacteria.

Studies of the cross-reactivity of antibodies to core glycolipid with assorted isolated, heterologous lipopolysaccharides (LPSs) confirm the conservation of core glycolipid epitopes among gram-negative bacterial species. However, the accessibility of core glycolipid epitopes to antibody in the intact bacterial cell may be affected by the cell surface structure. In studies with 125I-labeled monoclonal antibodies to core glycolipid that cross-react with isolated LPS, the degree to which antibodies can bind to LPS in the outer membrane of intact, viable, gram-negative bacterial cells was found to vary with the strain of bacteria tested. Sequestration of bacterial cell-bound LPS from antibody was confirmed in a smooth strain of Escherichia coli by means of immunoelectron microscopy. The inability of antibody to bind to membrane-bound LPS suggests that such sequestered LPS may also be unable to effect toxicity in the infected host until liberated by bacterial cell breakdown.

Antibodies, Bacterial↗
PubMed1990

Expression of glycolipid receptors to Shiga-like toxin on human B lymphocytes: a mechanism for the failure of long-lived antibody response to dysenteric disease.

Fresh and transformed human B lineage cells were found to be sensitive to the cytotoxic action of Shiga-like toxin (SLT), a bacterial cytotoxin. The toxin was specifically bound by the glycolipids globotriosylceramide and galabiosylceramide expressed on the surface of sensitive cells. Mutant Daudi cells selected for resistance to SLT cytotoxicity (SLTR20) were deficient in SLT-binding glycolipids and failed to bind SLT to their surface, suggesting a role for these glycolipids in the mediation of SLT cytotoxicity. Of a number of normal and transformed lymphoid and myeloid cells screened for SLT sensitivity, only B lymphoid cells were susceptible to SLT action. Moreover, B lymphoid cells were the only cells expressing the SLT binding glycolipids. In vitro B cell activation studies with Epstein-Barr virus and pokeweed mitogen both indicated that the vast majority of SLT-sensitive B cells belong to the IgG and IgA committed subset, whereas most IgM and IgM/D producing cells were resistant to SLT toxicity. The selective elimination of IgG and IgA committed cells may explain the production of only IgM class anti-SLT antibodies in Shigella-infected humans leading to the failure of long-term immunity to dysenteric disease.

Antibodies, Bacterial↗
PubMed1987

Glycolipids of the bovine pineal organ and retina.

Neutral and acidic glycolipids from the bovine pineal organ and neutral glycolipids from the bovine retina were characterized. The chemical structures of the isolated glycolipids were determined by means of carbohydrate analysis, methylation analysis, enzyme treatment, fatty acid analysis, long chain base analysis, mass spectrometry, NMR spectroscopy, and IR spectroscopy. GM3, GD3, and GT1 were the major bovine pineal organ gangliosides, GD3 accounting for 75% of the total gangliosides. Galactosylceramide, glucosylceramide, and lactosylceramide were found in both the bovine pineal organ and retina. Sulfatide was also present in both tissues. It had already been reported that the major bovine retina ganglioside was GD3 (Handa, S. & Burton, R.M. (1969) Lipids 4, 205-208). The glycolipid patterns of the two tissues were very similar to each other and quite different from those of other tissues.

Animals↗
PubMed1978

Characterization of major glycolipids in bovine erythrocyte membrane.

Several neutral glycolipids and gangliosides were isolated from bovine erythrocyte stroma. Their structures were determined by partial acid hydrolysis, methylation analysis, periodate oxidation and CrO3 oxidation. Two major neutral glycolipids were characterized as lactosylceramide and galactosyl(alpha1--3)galactosyl(beta1--4)N-acetylglucosaminyl(beta1--3)galactosyl(beta1--4)glucosyl(beta1--1)ceramide. Two major gangliosides were N-glycolylneuraminosyl(2--3)galactosyl(beta1--4)glucosyl(beta1--1)ceramide and N-glycolylneuraminosyl(2--3)galactosyl(beta1--4)N-acetylglucosaminyl(beta1--3)galactosyl(beta1--4)glucosyl(beta1--1)ceramide. Minor glycolipids were glucosyl- and galactosylceramide, glucosamine-containing tri- and tetraglycosylceramide, glucosamine-containing disialosylhexaglycosylceramide, and gangliosides containing N-acetylneuraminic acid. The ceramide moiety of each glycolipid contained perdominantly d18:1 sphingosine, and normal fatty acids of C16:0, C22:0, C24:0, and C24:1.

Animals↗
PubMed1982

Intermolecular interaction between glycolipids and glycophorin on liposomal membranes.

The haptenic activity of Forssman glycolipid was affected by glycophorin, and the interaction of glycophorin with lectins was also affected by the glycolipids, when both glycophorin and Forssman glycolipid or globoside were incorporated into the same phosphatidylcholine liposomes. Glycophorin incorporated into phospholipid membranes could interact with lectins, whereas that in glyceroglycolipid membranes could not. These findings suggest that glycophorin and glycolipids may interact, affecting the conformation of their sugar residues, probably through a carbohydrate-carbohydrate interaction. Such an interaction may cause suppression or stimulation of the reactivity of glycoconjugates with lectins or antibodies. Lactosylceramide showed only a slight effect on the interaction between glycophorin and lectins. We suggest that the structure of the sugar residues as well as the lateral distribution of molecules was important for the intermolecular interaction.

Animals↗
PubMed1983

The preparative separation of sialic acid-containing lipids from sulphate group-containing glycolipids from small intestine of different animals. Analysis by thin-layer chromatography and detection of novel species.

Acidic glycolipids (gangliosides and glycolipid sulphates) were purified from non-glycolipid contaminants by silicic acid chromatography of their acetylated derivatives. Acetylation converted gangliosides into non-polar neutral and weakly acidic derivatives. These were separated from acetylated sulphate-containing glycolipids by chromatography on DEAE-cellulose. The fractions thus isolated from small intestine of 7 different animals were analyzed by thin-layer chromatography. This revealed a considerable species-related variation of both gangliosides and sulphoglycolipids. Mass spectrometry demonstrated a novel ganglioside in guinea-pig small intestine and a novel sulphoglycolipid in mouse small intestine.

Acetylation↗
PubMed1984

Glycolipid composition of ascitic fluids from patients with cancer.

The glycolipid composition of ascitic fluids from nine patients with cancer and one pleural effusion from a hepatoma patient was studied. Glucosylceramide, lactosylceramide, globotriaosylceramide, and globotetraosylceramide were found in all samples and also in normal human serum. These glycolipids accounted for more than 90% of the neutral glycolipid fraction and the composition in ascitic fluids was similar to that in normal human serum. From ascitic fluids, several minor glycolipids, which could not be detected in normal human serum, were isolated and characterized by exoglycosidase treatment. Lactoneotetraosylceramide was found in eight samples of ascitic fluids, and globopentaosylceramide was detected in two samples from hepatoma and one from pancreatic cancer. A fucolipid which was converted to lactoneotetraosylceramide by alpha-L-fucosidase treatment was recognized in two samples from hepatoma patients. In the ganglioside fraction, GM3 was the predominant component both in normal human serum and in ascitic fluid. The GM2 content in ascitic fluids was much higher than that in normal human serum. From these results, lactoneotetraosylceramide and GM2 are possible candidates as cancer markers, because they seemed to be derived from cancer tissues by shedding.

Ascites↗
PubMed1985

High performance liquid chromatographic analysis of long chain bases in intestinal glycolipids of adult and embryonic Japanese quails.

A new sensitive assay method for sphingoids, 4-D-hydroxysphinganine, sphingosine, and sphinganine, involving reversed phase HPLC was described. Chromatography of p-N-nitrophenylacetyl derivatives of the sphingoids showed sufficient resolution, and each peak showed a linear relationship between molar quantity and area response, from 10 pmol to 10 nmol. The method was applied to the analysis of long chain bases in intestinal glycolipids from embryonic and adult Japanese quails. At the embryonic stage of 12 days' incubation, 4-D-hydroxysphinganine accounted for about 40% of the long chain bases of glycolipids, a concentration comparable to that in adult tissue. Egg yolk, which is an exclusive exogenous nutrient mixture supplied by the mother, contained only a few percent of 4-D-hydroxysphinganine as a glycolipid component. While, [3H]palmitic acid administered to embryos was incorporated into 4-D-hydroxysphinganine as well as sphingosine and sphinganine. These results suggest that sphingoids of intestinal glycolipids including 4-D-hydroxysphinganine are synthesized in the tissue, excluding the possibility of their exogenous origin in the embryonic tissue.

Animals↗