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PubMed1994

A novel soluble form of mouse VCAM-1 is generated from a glycolipid-anchored splicing variant.

VCAM-1 is a cytokine-induced endothelial adhesion molecule which belongs to the immunoglobulin (Ig) superfamily and mediates the binding of various leukocytes. In addition to the 110-kDa form of VCAM-1, we have found four additional glycoproteins on mouse brain-derived endothelioma cells after stimulation with tumor necrosis factor-alpha (TNF-alpha), which are recognized by several monoclonal antibodies against VCAM-1. Biochemical analysis revealed that the two smaller proteins (35 kDa and 37 kDa) are intracellular precursors of the two larger forms (44 kDa and 45 kDa), that the 44 kDa and 45 kDa proteins are glycolipid-anchored at the cell surface and that they differ in their N-glycosylation. Most likely they are identical to the recently identified glycolipid-anchored splice variant of VCAM-1, since they are recognized by the M3 antiserum which we raised against a peptide from the unique protein domain of this splicing variant. With the help of this antiserum we could show by immunohistology that the corresponding VCAM-1 protein variant is induced in vivo by lipopolysaccharide (LPS) on endothelium of the mouse. In addition, we found a 42-kDa soluble form of VCAM-1 in the serum of LPS-stimulated mice, which was recognized by the M3 antiserum. This soluble form was undetectable in the serum of unstimulated mice in contrast to the soluble 100-kDa form of VCAM-1 which was clearly detected in serum of unstimulated mice and only increased 2-3-fold upon stimulation with LPS. Thus, only the expression of the 42-kDa shredded form and not of the 100-kDa soluble form of VCAM-1 is strictly dependent on stimulation by LPS.

Animals↗
PubMed1989

Electron ionization mass spectrometry for sequence analysis of glycosphingolipid mixtures by fractional evaporation in the ion source. Mass spectrometric evidence for an eleven-sugar glycolipid.

This paper describes the use of electron ionization mass spectrometry for structural characterization of a mixture of glycosphingolipids from a single human kidney and presents mass spectrometric evidence for the presence of an eleven-sugar glycolipid. A large amount of structural information is obtained from minor glycolipid constituents having long sugar chains by a fractional evaporation in the ion source, achieved by steadily increasing the ion-source temperature.

Carbohydrate Sequence↗
PubMed2001

Structure-activity relationship of mycoloyl glycolipids derived from Rhodococcus sp. 4306.

Novel mycoloyl glycolipids with short carbon chains were isolated and purified from Rhodococcus sp. 4306, a soil origin of Actinomycetales. Their chemical structures were identified as trehalose 6,6'-dimycolate (TDM), trehalose 6-monomycolate, glucose 6-monomycolate, mannose 6-monomycolate and fructose 6-monomycolate. The length of carbon chains and number of double bonds of mycolic acids were C(34), C(36)and C(38)saturated, monoenoic and dienoic molecular species, which were much shorter than those of Mycobacterium tuberculosis (C(78-88)monoenoic and dienoic). Among them, only TDM could induce prominent granulomatous inflammation of the lung and spleen in mice. By contrast, other mycoloyl glycolipids induced mild lesions. The small-sized TDM of Rhodococcus possessed granulomatogenic activity, however, the toxicity was much lower than that of M. tuberculosis. Rhodococcal TDM was composed of mycolic acid with the shortest carbon chains, when compared to granulomatogenic TDM of Mycobacterium, Nocardia and Rhodococcus reported previously. Our results imply that rhodococcal TDM is a pathogenetic factor similar to that of M. tuberculosis, although rhodococcal TDM exhibits low toxicity.

Actinomycetales Infections↗
PubMed1991

Structural analysis of a glycosylphosphatidylinositol glycolipid of Leishmania donovani.

A glycosylphosphatidylinositol (GPI) glycolipid antigen recognized by sera from patients with visceral leishmaniasis was isolated from Leishmania donovani promastigotes. The carbohydrate moiety was cleaved from the lipid part by digestion with specific phosphatidylinositol phospholipase C. After separation, structural analysis was carried out on the phosphorylated inositol oligosaccharide and the alkylacyl glycerol. The following major structures were found: [formula: see text] The presence of the conserved sequence Man alpha 1-2Man alpha 1-6Man alpha 1-4GlcN-PI of glycosyl phosphatidylinositol protein anchors in this antigen may be consistent with a precursor role of Leishmania glycosyl phosphatidylinositol anchored proteins for this glycolipid.

Animals↗
PubMed1990

Glycolipid transfer protein and intracellular traffic of glucosylceramide.

Glycolipid transfer protein (GL-TP), a nonglycosylated protein with a molecular weight of 22,000 K, has been purified from pig brain. The protein transfers, by a carrier mechanism, glycolipids with a beta-glucosyl or beta-galactosyl residue directly linked to either ceramide or diacylglycerol. GL-TP appears to be present in most animal cells, and evidence has been obtained which indicates that it is a cytoplasmic protein. Little is known about the function of GL-TP. Current evidence indicates that glycosphingolipid glycosylation occurs at the luminal side of the Golgi apparatus, except for the glucosylation of ceramide, which has been shown to occur at the cytoplasmic side of the Golgi or endoplasmic membrane. It appears most likely that GL-TP participates in the intracellular traffic of glucosylceramide.

Animals↗
PubMed1989

Menstrual cycle-associated alteration of sulfogalactosylceramide in human uterine endometrium: possible induction of glycolipid sulfation by sex steroid hormones.

The human uterine endometrium is a tissue in which cell proliferation and differentiation are strictly controlled by sex steroid hormones, and these hormone-controlled cellular events occurring in association with the menstrual cycle of the uterine endometrium should be accompanied by characteristic molecular and metabolic changes. To characterize the menstrual cycle at the molecular level, we analyzed the glycolipids of human uterine endometrium in the proliferative and secretory phases of the menstrual cycle. Neutral glycosphingolipids from uterine endometrium comprised globo-series glycosphingolipids, such as GlcCer, LacCer, Gb3Cer, and Gb4Cer, and the relative concentrations remained constant in the two phases. However, in the case of acidic glycosphingolipids, although the concentrations of sialoglycosphingolipids remained at constant levels in the two phases, sulfatide, I3-SulfoGalCer, dramatically increased from the proliferative to the secretory phase, amounting to 7-17 nmol/g dry weight in the proliferative phase and 115-245 nmol/g dry weight in the secretory phase. Since sulfatide was the only glycolipid that changed in association with the menstrual cycle, it is likely that the sulfotransferase responsible for the synthesis of sulfatide might be induced by sex steroid hormones, estrogen and progesterone, and that sulfatide might play an essential biological role in the secretory phase of the menstrual cycle in the uterine endometrium.

Cerebrosides↗
PubMed1989

Sulfhydryl groups in glycolipid transfer protein: formation of an intramolecular disulfide bond and oligomers by Cu2+-catalyzed oxidation.

Glycolipid transfer protein (GLTP) purified from pig brain facilitates the transfer of various glycolipids between lipid bilayers. Purified GLTP migrates as two bands of different mobility in SDS-polyacrylamide gel electrophoresis (SDS-PAGE) under non-reducing conditions. The slower component and the faster component constituted about 80% and about 15%, respectively, of purified GLTP. Treatment of GLTP with 45 microM CuSO4 resulted in a decrease in the slower component, an increase in the faster component, and the formation of oligomeric components. The faster and oligomeric components were quantitatively converted to the slower component by reduction with 2% 2-mercaptoethanol in the presence of 1% SDS. The formation of oligomeric components was enhanced by increasing the concentration of CuSO4 to 450 microM and 4.5 mM. Oxidation of GLTP catalyzed by CuSO4 resulted in a decrease in the transfer activity and an increase in the apparent binding affinity of GLTP to 1-O-(beta-D-galactopyranosyl)-N-[10-(1-pyrenyl)decanoyl]-D-erythro- sphingosine (PyrGalCer). The oligomeric components and the monomeric components were isolated by chromatography on a Sephadex G-75 column. It was found that GLTP in fractions enriched with the monomeric components had very high transfer activity and is responsible for most of the transfer activity in the oxidized GLTP. Treatment of GLTP with 1.27 mM HgCl2 resulted in a formation of components unresolvable on SDS-PAGE and also resulted in a reduction of the transfer activity to one-third. However, no obvious change in the binding affinity of GLTP to PyrGalCer was observed by HgCl2 treatment. Treatment with 2-mercaptoethanol restored the activity of GLTP inactivated by HgCl2, whereas the activity inactivated by CuSO4 was not restored by treatment with 2-mercaptoethanol. These results suggest that the transfer activity depends on the turnover rate of the GLTP-PyrGalCer complex which is affected by modification of sulfhydryl groups of GLTP. The sulfhydryl group content of GLTP was estimated by the use of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). A value of 2.2 mol sulfhydryl groups per mol of GLTP was found in the presence of 0.5% SDS and one sulfhydryl group in a GLTP molecule was very rapidly oxidized in the native state, from which it is assumed that the slower component contains three sulfhydryl groups per GLTP molecule and the faster component contains one sulfhydryl group and one disulfide bond per GLTP molecule.

Animals↗
PubMed1996

Regulation of glycolipid sulfotransferase by tyrosine kinases in human renal cancer cells.

Glycolipid sulfotransferase activity in a human renal cancer cell line, SMKT-R3, is enhanced by the action of growth factors such as EGF, TGF-alpha and HGF, whose receptors possess tyrosine kinase domains. We investigated whether tyrosine kinases are involved in the regulation of the sulfotransferase in the cells by using specific tyrosine kinase inhibitors. Genistein and tyrphostin 51 not only cancelled the enhancement of the sulfotransferase by EGF but also reduced the enzyme level to a point much lower than that seen in non-treated cells, whereas they did not affect the sulfotransferase activity in vitro. The activity-reducing effects of genistein were dose- and time-dependent. Genistein also inhibited the cell growth of SMKT-R3 cells. Western blotting using anti-phosphotyrosine monoclonal antibody revealed a tyrosine-phosphorylated protein with an apparent molecular mass of 116 kDa in the non-treated cells. The EGF receptor was tyrosine-phosphorylated by the addition of EGF. The phosphorylations of the 116 kDa protein and EGF receptor were attenuated by co-incubation with genistein. These results indicate that tyrosine kinases including the EGF receptor are involved in the growth of SMKT-R3 cells and in the regulatory mechanisms of glycolipid sulfotransferase in the cells.

Cell Division↗
PubMed1985

Genetic and nongenetic control of the immune response of mice to a synthetic glycolipid, stearylisomaltotetraose.

Evidence for genetic control of antibody response to stearylisomaltotetraose (ST-IM4), a chemically defined synthetic glycolipid, was studied in various mouse strains. Anti-glycolipid antibodies were induced by repeated injections of ST-IM4 in complete Freund's adjuvant. C57BL and CBA/J mice were found to be good responders, while A/J, SJL/J, and AKR/J mice were poor responders. Responsiveness is independent of the H-2 genotype since AKR/J and CBA/J mice share the same H-2 locus. In addition, B10.A and B10.PL mice developed antibody levels similar to those of C57BL. The immunoglobulin heavy-chain locus (IgCH) was also found not to control antibody levels to ST-IM4 since C57BL and SJL/J mice share the same IgCH allotype. In C58/J mice, wide variation in response was observed among individual mice. Study of the response to ST-IM4 in 12 breeder pairs from different family lines of the C58/J colony also indicated that the regulation of the immune response to ST-IM4 is apparently more complex than can be explained by single gene control. C58 mice, unlike many other strains, had very low preimmune titers.

Animals↗
PubMed1970

Caracterisation de glycolipides dans une souche de Nocardia brasiliensis.

Several glycolipid fractions have been isolated from the bound lipids of N. brasiliensis. The main fraction was characterized as a monoester of nocardomycolic acids and D-arabinose. Fractionation of the free lipids yielded a glycolipid fraction consisting of nocardomycouc acids, arabinose, galactose and several amino acids. This last fraction appears to be similar to wax D of Mycobacteria; mild acid treatment of this fraction produced arabinose mononorcardomycolate.

Journal Article↗
PubMed1985

Structural characterization of a blood group A heptaglycosylceramide with globo-series structure. The major glycolipid based blood group A antigen of human kidney.

A blood group A glycosphingolipid with the globo-series structure has been isolated from human kidney and structurally characterized. The structure was shown by mass spectrometry and proton NMR spectroscopy of the intact permethylated and permethylated-reduced derivatives together with degradation studies to be, GalNAc alpha 1----3Gal(2----1 alpha Fuc)beta 1----3GalNAc beta 1----3Gal alpha 1----4Gal beta 1----4Glc beta 1----1 Ceramide. This glycolipid reacts with both polyclonal and monoclonal anti-A blood group typing antisera and it is the major glycolipid based blood group A antigen present in the human kidney.

ABO Blood-Group System↗
PubMed1992

Different patterns of glycolipid antibody reactivity: lower motor neuron syndromes vs. immunization.

High titers of serum antibodies against GM1 ganglioside occur frequently in patients with lower motor neuron (LMN) syndromes. We compared the specificities of the antiganglioside antibody reactivities in LMN patients with those arising after immunization of Lewis rats with several ganglioside containing preparations including purified GM1, human central nervous system (CNS) grey matter and white matter. Serums with high titers of anti-GM1 antibodies from patients with LMN syndrome usually showed limited cross-reactivity to other glycolipids but often bound to a Gal(beta 1-3)GalNAc-containing neoglycoprotein. In contrast, serums with anti-GM1 antibody arising after immunization showed broad cross-reactivity with other glycolipids but did not bind to the neoglycoprotein. We conclude that the serum patterns of antiganglioside antibody reactivity secondary to immunization with gangliosides and CNS components are different from the natural autoantibodies found in LMN patients. The antiganglioside antibodies seen in LMN patients are unlikely to be a result of autoreactivity to gangliosides after nervous tissue damage.

Animals↗
PubMed1992

Structural characterization of a novel diglycosyl diacylglyceride glycolipid from Rhizobium trifolii ANU843.

A novel glycolipid was isolated by chloroform-methanol extraction of Rhizobium trifolii ANU843 cells. Compositional analysis, methylation studies, 1H NMR and spectroscopies led to the identification of a diglycosyl diacylglyceride: 1,2-di-O-acyl-3-O-[alpha-D-glucopyranosyl-(1----3)-O-alpha-D- mannopyranosyl]glycerol. Iso-hexadecanoic and anteiso-heptadecanoic acids were the predominant fatty acids esterifying the glyceryl moiety, but a microheterogeneity in fatty acid composition was found, resulting in at least five distinct molecular species of the glycolipid. Although widespread in plants, animals and Gram-positive bacteria, glycosyl glycerides have been seldom reported in Gram-negative bacteria and this work is the first evidence of their occurrence in the bacterial family Rhizobiaceae.

Carbohydrate Sequence↗
PubMed1998

A kinetics approach to the characterization of an IgM specific for the glycolipid asialo-GM1.

The unique features of protein recognition of membrane-anchored glycolipids were investigated by surface plasmon resonance (SPR) monitoring of antibody interactions with glycolipids contained in liposomes. Several positive hybridomas belonging to the IgM and IgG classes were identified when tested for binding to the glycosphingolipid asialo-GM1 (Gal beta1-3GalNAcl beta1-4Gal beta1-4Glc beta1-1-Ceramide). Preliminary screening by enzyme immunoassay and thin layer chromatography (TLC) followed by immunostaining indicated that only those of the IgM type showed specificity for this glycosphingolipid. One of the IgMs, H2G10, was purified and further characterized using a SPR technique that involved antibody binding to liposomal asialo-GM1. This method generated kinetic and affinity constants for the interaction and confirmed the specificity of H2G10 for the terminal galactose of asialo-GM1. Interestingly, inhibition of antibody binding to asialo-GM1 liposomes by the asialo-GM1 tetrasaccharide reduced the total amount of bound antibody but increased the affinity of the antigen-antibody interaction due to an inverse relationship between tetrasaccharide concentration and the H2G10 dissociation rate constant. We believe that this effect is due to the selective inhibition of lower valency binding by the tetrasaccharide which, in turn, promotes higher avidity antibody-carbohydrate interactions. The observation that slower dissociation rate constants were also observed at high antigen to antibody ratios supports this interpretation. These results highlight the insight that kinetic data can provide in efforts to promote and inhibit high avidity interactions such as those involving proteins and carbohydrates.

Antibodies, Monoclonal↗
PubMed1992

Globotriaosyl ceramide glycolipid in seminoma: its clinicopathological importance in differentiation from testicular malignant lymphoma.

Glycolipids were biochemically extracted from 14 specimens of seminoma, 2 of testicular malignant lymphoma (both of which were difficult to differentiate from seminoma with a high mitotic index) and 4 of normal testicle. The pattern of their expression was compared. Marked accumulation of globotriaosyl ceramide was observed in seminoma but it was present in a small amount in testicular malignant lymphoma. Differentiation between seminoma and malignant lymphoma is sometimes difficult by histopathological findings but it is considered to be greatly facilitated by examination of the pattern of glycolipid expression.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1993

A carbohydrate-carbohydrate interaction between galactosylceramide-containing liposomes and cerebroside sulfate-containing liposomes: dependence on the glycolipid ceramide composition.

Galactosylceramide (GalCer) and cerebroside sulfate (CBS) are the major glycolipids found in myelin. They occur in greater concentrations in this membrane than any other. Recently, it was reported that these two glycolipids can participate in a heterotypic carbohydrate-carbohydrate interaction [Hakomori et al. (1991) Glycoconjugate J. 8, 178]. In the present study, the effect of changes in the ceramide composition of both GalCer and CBS on this interaction has been examined. The interaction was monitored by measuring the aggregation of small unilamellar phosphatidylcholine/cholesterol liposomes containing GalCer with similar liposomes containing CBS, through the increase in optical density at 450 nm. Aggregation depends on the addition of a divalent cation and varies inversely with the ionic radius of the cation. Aggregation occurred at millimolar concentrations of divalent cation and was inhibited and reversed by the addition of EDTA. A lesser degree of homotypic self-aggregation of GalCer and of CBS liposomes also occurred in the presence of divalent cations, but the sum of this self-aggregation was significantly less than the heterotypic interaction between the two types of liposomes. Changes in the ceramide composition of GalCer and CBS significantly affected the extent of their interaction with each other. Increasing the fatty acid chain length of either GalCer or CBS resulted in increased aggregation. Hydroxylation of the fatty acid also increased the degree of aggregation of GalCer and CBS liposomes. These findings indicate that a divalent cation-mediated GalCer-CBS interaction could play a role in cell recognition and membrane adhesion phenomena such as the formation of compact multilamellar myelin.(ABSTRACT TRUNCATED AT 250 WORDS)

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1991

Glycosphingolipids: 2H NMR study of the influence of carbohydrate headgroup structure on ceramide acyl chain behavior in glycolipid-phospholipid bilayers.

Galactosyl- and glucosylceramide, globoside, and dihydrolactosylceramide, bearing [2,2-2H2]stearic acid, have been studied at a concentration of 10 mol% in bilayers of dimyristoylphosphatidylcholine by 2H NMR. The quadrupolar splitting delta vQ of the C2 deuterons were measured at several temperatures in the range of 30-60 degrees C. Spin-lattice relaxation times T1 of C2 deuterons were determined in the same temperature range for all lipids but globoside. T1 values at 30 and 50 degrees C were unexpectedly short (6-8 ms), indicating reduced mobility of the ceramide acyl chains compared to that of the host phospholipid. At all temperatures, both delta vQ and T1 were essentially identical for the monoglycosylated species, GalCer and GlcCer, indicating that the order and dynamics of the upper portion of the fatty acyl chain are insensitive to this small change in the headgroup structure. In the case of globoside, where the glycolipid headgroup is equivalent to that of GlcCer extended by three sugar residues, values for the quadrupolar splittings associated with the acyl chain C2-position were very close to those obtained for Gal- and GlcCer. In contrast, the delta vQ values obtained for the diglycosyl species, LacCer, were significantly different at all temperatures. This different behavior of LacCer relative to that of the other glycolipids most likely originates from an orientational change of the acyl chain at the C2-position due to the absence of a 4,5 double bond in dihydrosphingosine. T1 values for the GlcCer and GalCer systems increased with temperature, indicating that the motions responsible for relaxation were in the short correlation time regime.(ABSTRACT TRUNCATED AT 250 WORDS)

Ceramides↗
PubMed1987

Isolation of two glycolipid transfer proteins from bovine brain: reactivity toward gangliosides and neutral glycosphingolipids.

Two glycolipid transfer proteins that catalyze the transfer of gangliosides and neutral glycosphingolipids from phosphatidylcholine vesicles to erythrocyte ghosts have been isolated from calf brain. Purification procedures included differential centrifugation, precipitation at pH 5.1, ammonium sulfate precipitation, and gel filtration on Sephadex G-50 and G-75. The final stage employed fast protein liquid chromatography (Mono S), producing two peaks of activity. Apparent purity of the major peak (TP I) was approximately 85-90%, as judged by sodium dodecyl sulfate/urea-polyacrylamide gel electrophoresis. That of the minor fraction (TP II) was less. The major band of both fractions had a molecular mass of approximately 20,000 daltons. Both proteins catalyzed the transfer of ganglioside GM1 as well as asialo-GM1, but transfer protein I was more effective with di- and trisialogangliosides. Transfer protein II appeared to be somewhat more specific for neutral glycolipids in that GA1 was transferred more rapidly than any of the gangliosides; however, lactosylceramide transfer was relatively slow. Neither protein catalyzed transfer of phosphatidylcholine.

Animals↗