Types Of Gangliosides Research Articles

Interaction of gangliosides with plasma low density lipoproteins

The role of gangliosides in the reception of low density lipoproteins (LDL) was studied using as targets mouse ascites hepatoma 22a (MAH) cells which bind LDL through a specific high affinity receptor. Low density lipoprotein binding and uptake by MAH cells decreased after brief treatment of the cells with neuraminidase to partially remove surface sialic acid residues. The LDL uptake capability of the neuraminidasetreated MAH cells was fully restored after incorporation of exogeneous GM1- and GD1a-gangliosides into the cell surface. In contrast, free (extracellular) gangliosides inhibited LDL uptake by native MAH cells. This inhibitory effect was seen at ganglioside concentrations corresponding to the ganglioside content of serum and was most pronounced with gangliosides whose sialic acids were linked to a terminal galactose residue (GM3, GD1a, GT1b) but was smaller or absent with gangliosides whose sialic acids were attached to an internal galactose (GM1, GM2). The binding of gangliosides to LDL was structure and concentration dependent, saturable and trypsin sensitive. The LDL-ganglioside interaction was further investigated by steady state fluorescence spectroscopy. Changes in the LDL fluorescence polarization were observed with as little as 0.01 μM concentrations of the gangliosides. The magnitude and nature of the effect depended on the type of ganglioside. We conclude that the LDL surface possesses sites recognizing specific carbohydrate sequences of glycoconjugates and that changes in the cell surface concentrations of sialic acids significantly modulate the LDL uptake. It is postulated that shedding of gangliosides into the blood stream may be a factor involved in regulation of cholesterol homeostasis.

Complement-dependent immune damage to liposomes containing gangliosides

Rabbit antiserum against mixed beef brain gangliosides served as an excellent source of antibodies to gangliosides G M1, G M3, G D1a, G D1b, and G T1b. Immune potency of antiserum was determined by complement-dependent damage to liposomes containing gangliosides as antigens. Antibody levels in antiserum to mixed gangliosides, when tested against individual gangliosides, were equivalent or superior to the levels obtained by immunization of rabbits with purified individual gangliosides. Naturally occurring antibodies to G M1, G D1b, and G M3 were observed in preimmunization sera. The levels of these natural antibodies, although easily high enough to serve as antiserum sources for liposome assay, were increased substantially following immunization. High titers of antibodies to G M1 and G D1b were observed in certain individual guinea pig sera, and selection of individual non-reacting guinea pig sera was necessary in order to obtain suitable complement sources when testing rabbit antibodies to liposomal G M1 and G D1b. The maximum plateau level of trapped glucose release from liposomes in the presence of saturating levels of antigen, antiserum, and complement was influenced strongly both by the method of removing untrapped glucose during liposome preparation and by the type of ganglioside incorporated into the lipid bilayer.

Gangliosides in postmitotic retina of chick embryo: Changes in vivo and in cell cultures

Developmental changes in ganglioside composition of postmitotic neural retina of chick embryo were analyzed by thin-layer chromatography. Gangliosides were identified by comparing their chromatographic mobilities with reference standards. The outstanding changes are decrease in the concentration of GD3L and increase in GD1a and GM1 concentrations. By depleting Müller glia cells from retina tissue of 13- and 16-day embryos (R 13, R 16) we determined that the bulk of the major gangliosides is associated with the neurons. Analysis of gangliosides in monolayer cultures of R 13 and R 16 cells highly enriched for Müller cell-derived gliocytes indicated that these cells express the same types of gangliosides as neurons, but in somewhat different concentrations and relative proportions; however, after time in culture these cells showed ganglioside types and changes in ganglioside profile that are not characteristic of normal retina. The latter observation is consistent with other evidence that the phenotype of Müller glia cells becomes altered in monolayer culture. In contrast to cultures of early embryonic retina, in organ cultures of later postmitotic retina, ganglioside composition did not continue to change as in normal development. This suggests that in postmitotic retina, normal developmental progression of ganglioside changes requires systemic and/or other conditions which are missing or altered when this tissue is isolated and cultured in vitro.

Calorimetric and fluorescence characterization of interactions between enkephalins and liposomal and synaptic plasma membranes containing gangliosides.

The interactions of the opioid peptide [D-Ala2]methionine-enkephalinamide with dipalmitoylphosphatidylcholine (DPPC) large unilamellar vesicles containing gangliosides GM1, Gd1a, and Gt1b and synaptic plasma membranes selectively enriched with dimyristoylphosphatidylcholine (DMPC) and ganglioside Gd1a have been investigated by using high-sensitivity differential scanning calorimetry. In the absence of gangliosides, the addition of enkephalinamide in concentrations of up to 10(-3) M does not induce any appreciable change in the heat capacity function of DPPC. In the presence of gangliosides, however, changes in the heat capacity function were observed with as little as micromolar concentrations of the enkephalinamide; the same is true for DMPC-Gd1a-enriched synaptic membranes. The magnitude and the nature of the enkephalinamide effect depend on the type of ganglioside studied. For DPPC vesicles containing ganglioside GM1 only a slight broadening in the heat capacity function and a small upward shift in the transition temperature were observed. For DPPC vesicles containing ganglioside Gd1a the effect was more dramatic; enkephalinamide concentrations as low as 10(-5) M caused the appearance of two well-defined peaks in the heat capacity function in contrast to the one peak observed in the absence of enkephalinamide. In the case of DPPC vesicles containing ganglioside Gt1b the enkephalinamide effect was seen at concentrations of 10(-4) M or higher. Synaptic plasma membranes were isolated from bovine brain, selectively enriched with exogenous lipid, and their thermotropic behavior was characterized by steady-state fluorescence spectroscopy and differential scanning calorimetry. This lipid enrichment results in the appearance of a membrane phase transition otherwise absent in the intact membrane preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of early neuronal subpopulations in avian neural crest cell cultures

Gangliosides were employed as early differentiation markers to investigate how phenotypic diversity is generated in the vertebrate neutral crest cell population. Chromatographic analysis of metabolically labeled glycolipids from neural crest derivatives revealed that glia cell precursors synthesize a characteristic subset of the ganglioside types produced by dorsal root ganglion neurons. The ganglioside synthesis pattern of neural crest cultures is similar to that of glial precursors, but gangliosides characteristic of neurons are also detectable. To determine whether neuronal gangliosides are expressed by every cell in neural crest cultures, or by discrete cell subpopulations, crest cultures were stained immunocytochemically with monoclonal antibody A2B5 which recognizes a neuron-specific ganglioside in the GQ fraction. A2B5 was found to bind to about 1% of migratory stage neural crest cells isolated from neural tube explants after 1 day in culture. These A2B5 + cells were postmitotic and exhibited a uni- or bipolar neuronal morphology. A second, larger (10–20%) population of A2B5 + cells appears after culturing cells from 1-day crest cell clusters an additional 1–2 days. These cells initially have the typical small, stellate morphology of crest cells but later extend one or more processes. [ 3H]Thymidine incorporation and cell counting studies show that the precursors to these cells had divided at least once in culture before becoming postmitotic and expressing A2B5 immunoreactivity. The second A2B5 + population does not appear in secondary cultures of crest cell clusters isolated from 2-day-old explants of neural tubes. Another monoclonal antibody, R24, which recognizes ganglioside GD3, binds to subpopulations of both neurons and nonneurons in sensory ganglion cultures. In neural crest cultures R24 binds to a large subpopulation of cells, but not to A2B5 + ones. The significance of this immunostaining pattern is not yet understood. The early appearance of subpopulations, and the presence of heterogeneity in neural crest cultured under a variety of conditions suggest that intrinsic cellular mechanisms might generate subpopulations within the neural crest upon which environmental factors act.

Synthesis of gangliosides by cultured oligodendrocytes

Gangliosides are enriched in the nervous system compared to other tissues. The synthesis of gangliosides by monolayer cultures of isolated oligodendrocytes has not previously been investigated. Cells were labeled with [3H] galactose at preselected times and gangliosides isolated by phase partition, purified, and identified by chromatography. Cultured oligodendrocytes showed selectivity in their synthesis of gangliosides, which was expressed in the type of ganglioside synthesized as well as in the change of incorporation over time in culture. For the first ten days, there was very little incorporation of [3H] galactose in gangliosides, but this was followed by a stimulation of uptake for GM3, GM1/GD3, and GD1 gangliosides, reaching a maximum after approximately 25-30 days in vitro. There was little incorporation into GM2 or trisialogangliosides throughout the life of the cultures. Since oligodendrocytes synthesize extensive membranes during this period, one may speculate that the de novo-synthesized gangliosides are used for membranes.

A new type of ganglioside. The structures of three novel gangliosides from the fat body of the frog.

Three unusual gangliosides were isolated from frog fat body, and their structures were characterized. The carbohydrate structures were elucidated by determination of the molar ratio of the individual monosaccharides, methylation analysis, galactosidase treatment, and chromium trioxide oxidation studies. The following novel structures were proposed: [Formula: see text].

Polystyrene-adsorbed gangliosides for investigation of the structure of the tetanus-toxin receptor.

This paper describes the elaboration, using cholera toxin and GM ganglioside as a model system, of versatile, sensitive methods allowing simple determinations of the specific binding of protein ligands to polystyrene‐adsorbed gangliosides, and, secondly, the application of these methods to the tentative identification of the receptor structure for tetanus toxin.The adsorption characteristics and the ligand‐binding properties of the adsorbed gangliosides were determined, and the specificity and sensitivity of the various ligand‐detection methods (radio‐isotope; enzyme‐linked antibody or water‐vapour condensation) defined. The adsorption did not vary with the type of ganglioside and was found to be linearly proportional to the square root of the incubation concentration and to the log of the incubation time. No difference in adsorption was seen between temperatures of 4 to 37 deg;C. As analyzed with cholera toxin, the polystyrene‐adsorbed ganglioside was structurally specific in binding; i.e. only GM1 was active while after hydrolysis by Vibrio cholerae sialidase also GD1a, GD1b and GT1b, for example, had the same activity as GM1. The affinity of cholera toxin for polystyrene‐adsorbed GM1 was similar to that for viable cells (Ka= 1.2 nM−1).Tetanus toxin was found to bind specifically to gangliosides of the G1b series (GD1b, GT1b and GQ1b) and though with less affinity, also to GT1a, GM1, GD1a and GD3. The binding affinity of tetanus toxin for the G1b gangliosides was less than that of cholera toxin for GM1. The studies showed that tetanus toxin has specific binding affinity for tetraose‐gangliosides with a disialosyl group linked to the inner galactose. It is conceivable that the natural binding structure for the tetanus toxin has the end sequence Galβ1 → 3Ga1NAcβ1 → 4Ga1(2← 8αNeuAc2 ← 3αNeuAc) which occurs in the ganglioside G1b series and possibly also in the oligosaccharide chains of certain cell membrane glycoproteins.

Blood-group-Ii-active gangliosides of human erythrocyte membranes.

More than ten new types of gangliosides, in addition to haematoside and sialosylparagloboside, were isolated from human erythrocyte membranes. These were separated by successive chromatographies on DEAE-Sephadex, on porous silica-gel columns and on thin-layer silica gel as acetylated compounds. Highly potent blood-group-Ii and moderate blood-group-H activities were demonstrated in some of the ganglioside fractions. The gangliosides incorporated into cholesterol/phosphatidylcholine liposomes stoicheiometrically inhibited binding of anti-(blood-group I and i) antibodies to a radioiodinated blood-group-Ii-active glycoprotein. The fraction with the highest blood-group-I-activity, I(g) fraction, behaved like sialosyl-deca- to -dodeca-glycosylceramides on t.l.c. Certain blood-group-I and most of the -i determinants were in partially or completely cryptic form and could be unmasked by sialidase treatment. Thus the I and i antigens, which are known to occur on internal structures of blood-group-ABH-active glycoproteins in secretions, also occur in the interior of the carbohydrate chains of erythrocyte gangliosides.

New Types of Gangliosides in Starfish with Sialic Acid Residues in the Inner Part of Their Carbohydrate Chains

Three gangliosides were isolated from the starfish by Folch's partition, dialysis, silicic acid column chromatography, Iatrobead column chromatography and preparative thin-layer chromatography. Partial acid hydrolysis of the three lipids in 0.1 N HCl at 80 degrees for 90 min liberated all the lactosyl ceramide and water-soluble degradation products, but no sialic acid. Gas-liquid chromatography of the trimethylsilylated methyl glycosides of the water-soluble products demonstrated the presence of arabinose in addition to the usual sugar units of gangliosides.

Biochemical studies of transneuronal degeneration: The effects of enucleation on the biochemical maturation of the chick optic tectum

The chick visual system is a useful model to study the biochemical consequences of transsynaptic degeneration. Following enucleation on the day of hatching, the deafferented chick optic tectum at days 12–16 fails to demonstrate the increased protein, glycoprotein and ganglioside content of normal optic tectum. Morphologic and biochemical studies suggest that the number of neurons and glia are not decreased in the deafferented optic tectum. However their surface membrane and intracellular constituents are decreased. Although enucleation produces a marked reduction in total ganglioside and fucosyl glycopeptide constituents, it does not alter the normal developmental changes in the profile of specific gangliosides or in the molecular weight of fucosyl glycopeptides. Within the limits of sensitivity of techniques employed, the effects of transneuronal degeneration on gangliosides and fucosyl glycopeptides appear to be primarily quantitative rather than qualitative. Once synapses are formed presynaptic terminals from the retina may have less effect on the types of gangliosides and the molecular weights of fucosyl glycopeptides than on the amounts of these constituents.

Blocks in Ganglioside Synthesis in Transformed Hamster Cells and Their Revertants

Abstract Hamster cells transformed by polyoma virus or by treatment with the chemical carcinogen dimethylnitrosamine and revertants from these transformed cells were examined for UDP-N-acetylgalactosamine:hematoside N-acetylgalactosaminyltransferase activity and for their types of gangliosides. Compared to normal cells, both the transformed and revertant cells showed 3 to 12% of the enzyme activity and a simplification of the ganglioside pattern. The presence of similar blocks in glycosyltransferase activity and ganglioside synthesis in these transformed cells and their revertants indicates that these blocks were not associated with the regulation of cell growth, but may be due to a common genetic change in transformed cells and their revertants that is not found in normal cells.

Glycosphingolipids and amines in neoplastic mast cells

Glycosphingolipids containing neuraminic acid (gangliosides) have been isolated from two lines of mouse neoplastic mast cells. Thin-layer chromatography and chemical analysis of these lipids suggest the presence of at least three different types of gangliosides: N-acylneuraminosyl-monoglycosylceramide, N-acylneuraminosylmonaminoglycosyl-triglycosylceramide and N-acyl-dineuranminosyl-monoaminoglyco-syldiglycosylceramide. The intracellular distribution of the gangliosides differs from cerebroside sulfate in that the neuraminic acid lipids are primarily found in small-particle fractions, but the cerebroside sulfate occurs mainly in the amine containing large-particle fractions. Density gradient centrifugation of this large-particle fraction has demonstrated that the cerebroside sulfate is retained in a subfraction showing high fumarase activity, characteristic of mitochondria, and separable from the amine containing granules. The chemical analysis of purified mast cell cerebroside sulfate showed an approximately equimolar ratio of sphingosine, hexose and sulfate.

The structure and the function of gangliosides.

AbstractGangliosides are found in the brain and other organs, and are composed of sphingosine, fatty acids, hexoses, and sialic acid. Types of gangliosides differ in the fatty acids and the sugar residues. The carbohydrate residue in the quantitatively predominating brain gangliosides is ganglio‐N‐tetraose, a tetrasaccharide. In these gangliosides, this residue combines with one or more molecules of sialic acid. The oligosaccharide part is a carrier of serologic properties. Gangliosides are characteristic lipid components of some neuronal membranes in the central nervous system, and can be localized on the synaptic apparatus of nerve cells in the cerebral cortex. Their site of occurrence and physiological action point to their participation in the transmission of impulses. It was in the brains of the mentally ill that gangliosides were first discoverd, and indeed their pathologic accumulation can possibly be attributed to congenital defect of enzymes involved in their synthesis or metabolism. Gangliosides are produced from their components by acceptor‐specific transferases.

Composition of gangliosides from human brain.

GANGLIOSIDES are lipids closely allied to the cerebrosides. They were so named because of their occurrence mainly in the ganglion cells of the nervous system, although gangliosides seem to exist in most parenchymatous organs. Klenk et al. 1, for example, have isolated gangliosides from brain, spleen and red cells. The composition of ganglioside from brain as given by Klenk had to be modified after the isolation of chondrosamine from brain ganglioside by us2, and in a recent paper Klenk et al. suggested its composition as follows : In the same paper they also assert the existence of only one type of ganglioside from brain.