Cell-type-specific markers for distinguishing and studying neurons and the major classes of glial cells in culture

We have used 4 cell-type-specific markers to identify individual glial and neuronal cells in dissociated cell cultures of neonatal rat sciatic nerve, dorsal root ganglia (DRG), optic nerve, cerebellum, corpus callosum, cerebral cortex and leptomeninges. Schwann cells were identified with antibodies against rat neural antigen-1 (Ran-1), neurons with tetanus toxin, astrocytes with antibody against the glial fibrillary acidic protein (GFAP) and oligodendrocytes with antibody against galactocerebroside. All of these ligands react with cell surface molecules except for anti-GFAP antibody which binds to intracellular glial filaments. Using two-fluorochrome immunofluorescence we have studied the distribution of various glycoproteins and glycolipids on these 4 major neural cell types in short-term cultures. We have found that (1) although Ran-1 is expressed on glial and neuronal tumours, it was not found on normal astrocytes, oligodendrocytes or neurons; (2) Thy-1 was present on fibroblasts and some neurons but not on the majority of leptomeningeal cells or on oligodendrocytes or astrocytes in short-term cultures (however, it was expressed on some astrocytes in longer term cultures); (3) the 'large external transformation sensitive' (LETS) protein could be detected on fibroblasts and leptomeningeal cells but not on neurons or glial cells; (4) GM1 was present on all neurons, most oligodendrocytes and approx. 50% of other cell types; sulfatide and GM3 were only detectable on oligodendrocytes, while globoside was only found on some neurons. In addition, we were able to identify putative microglial cells by the presence of cell surface receptors for IgG and by their phagocytic activity; they did not express and of the cell-type-specific defining markers.

Production of monoclonal antibodies specific for two distinct steric portions of the glycolipid ganglio-N-triosylceramide (asialo GM2)

Two hybrid cell lines were prepared by the fusion of mouse myeloma cells with the spleen cells of BALB/c mice that had been immunized with the glycolipid ganglio-N-triosylceramide (asialo GM2). The specificity of the monoclonal antibodies produced by these hybridomas, one an IgM and the other an IgG3, has been defined by hemagglutination inhibition, complement fixation, and lysis of glycolipid liposomes by antibody and complement. A major determinant recognized by the IgM antibody is the nonreducing terminal N-acetylgalactosamine including the C6 primary hydroxyl group, but excluding the C2-acetamide group of N-acetylgalactosamine, because oxidation with galactose oxidase produced a structure showing only minimal cross-reaction with the IgM but replacement of the N-acetyl group with an N-n-butyryl group produced a glycolipid that reacts with IgM antibody to the same extent as with the unmodified glycoplipd. A major determinant recognized by the IgG3 antibody is the terminal N-acetylgalactosamine including the C2-acetamido group, but excluding the C6 primary hydroxyl group of N-acetylgalactosamine, because replacement of the N-acetyl group with an N-n-butyryl group produced a glycolipid that did not react with the IgG3 antibody; in striking contrast the IgG3 antibody reacted with the C6-oxidized glycolipid as well as with the native glycolipid. Neither antibody reacted significantly with any other natural glycolipids tested including several that are structurally related to asialo GM2 such as ganglioside GM2, ganglio-N-tetraosylceramide (asialo GM1), or ceramide dihexoside. These results indicated that in addition to the fine structure specificity described above both antibodies recognize the nonreducing terminal GalNAc beta 1 leads to 4Gal structure. The strict antigenic specificity of these monoclonal anti-glycolipid antibodies indicates their great potential as specific probes for cell surface studies.

Isolation and characterization of gangliosides with a new sialosyl linkage and core structures. II. Gangliosides of human erythrocyte membranes

Eight monosialosylgangliosides, G1 to G8, have been isolated from human erythrocyte membranes and their structures have been determined. Gangliosides G4 and G7 have been characterized by having 2 leads to 6-linked sialic acid to galactose at their termini. Ganglioside G5 was a positional isomer of a brain ganglioside GM1 as to the linkage of sialic acid. Ganglioside G8 was characterized as a branched chain ganglioside similar to a fucoganglioside previously isolated but devoid of fucose, and it showed a strong blood group I activity. Structures of these four new gangliosides are shown below: (formula: see text).

Three types of blood group I specificity among monoclonal anti-I autoantibodies revealed by analogues of a branched erythrocyte glycolipid

Blood group I activities of the purified glycosphingolipid lacto-N-iso-octaosyl ceramide (Fromula: see text) and 8 of its analogues have been evaluated with 11 anti-I sera including 5 anti-I sera previously tested. All but one of the antisera were inhibited by the lacto-N-iso-octaosyl structure. Three types of I-specificity could be distinguished although none of the anti-I sera was identical in its inhibition patterns with the nine glycophingolipid analogues. The anti-I sera Ma and Woj represent the first type and require an intact Galbeta1 leads to 4GlcNAcbeta1 leads to 6 chain, the anti-I sera Step, Gra, Ver, and Ful represent the second type which requires Galbeta1 leads to 4GlcNAcbeta1 leads to 3 chain with branching, and the anti-I sera Phi, Da, Sch, and Low belong to the third type which requires both branches to be intact. Anti-I antibodies varry in their ability to react with their antigenic determinants in the presence of external substitutions with alpha-linked galactose or sialic acid.

Blood-group-I activity associated with band 3, the major intrinsic membrane protein of human erythrocytes

Affinity chromatography of radioiodinated solubilized erythrocyte stroma and of radioiodinated purified Band 3 on an anti-(blood-group I)-adsorbent column showed blood-group-I activity associated with a subpopulation of Band 3. The specificity of binding was confirmed by inhibition with known blood-group substances in radioimmunoassays.

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.

Association of the glycolipid pattern with antigenic alterations in mouse fibroblasts transformed by murine sarcoma virus

The level of the neutral glycolipid, Galnac beta 1 leads to 4 Gal beta 1 leads to 4Glc leads to Cer (asialo GM2), in BALB/c 3T3 mouse fibroblasts transformed by Kirsten murine sarcoma virus (3T3KIMSV) was greatly increased compared to the nontransformed parental cells (3T3). This elevated chemical quantity was found to be localized on the surface of intact cells and accessible to external reagents, as detected by immunofluorescence and labeling with galactose oxidase: NaB3H4. Furthermore, immunization of rabbits with 3T3KiMSV cells but not with 3T3 cells resulted in antibody production against asialo GM2. These results demonstrate the potential usefulness of glycolipids as tumor-associated cell surface markers.

Status of blood group carbohydrate chains in ontogenesis and in oncogenesis

Blood group ABH determinants in human erythrocytes are carried by four kinds of glycolipid carbohydrate chains, differing in their structural complexity. They are Aa, Ab, Ac, and Ad for A variants, and H1, H2, H3, and H4 for H variants (Table I and Fig 1). Based on the surface labeling of A variants and on the reactivity of erythrocytes to antibodies directed against H3 and against its degradation products, it is concluded that complex variants of A or H determinants (Ac and Ad/or H3 and H4) are absent or significantly low in fetal erythrocytes (80-150 days after gestation) and in new born erythrocytes, whereas these complex structures are fully developed in adult erythrocytes. In contrast, A determinants linked to simpler carbohydrate chains (Aa, Ab variants) are fully developed before birth and do not show significant change after birth. The precursor of blood group carbohydrate chains seems to be abundant in fetal or newborn erythrocytes. This assumption is based on the higher reactivity of fetal or newborn erythrocytes to an antibody, which is directed against the precursor N-acetylglucosaminly beta1 leads to 3 galactosyl beta1 leads to 4 glucosylceramide than in adult erythorocytes. Reactions of glycolipids of gastrointestinal mucosa, with antibodies directed against H3 glycolipid and its degradation products, were compared to that of gastrointestinal tumors. The reaction to bela Glc NAc1 leads to 3 beta Gall leads to 4 Glc leads to ceramide (structure 4), which is the precursor of all blood group glycolipids, was consistently high in many cases of tumor glycolipid than that of normal glycolipid. This as well as other evidence supports a general concept that the process of ontogenesis of a blood group carbohydrate chain occurs as step-by-step elongation and arborization, and that blocking of such a development of a carbohydrate chain occurs in the process of oncogenesis.

Long-chain neutral glycolipids and gangliosides of murine fibroblast lines and their low- and high-tumourigenic hybrids

The patterns of long-chain neutral glycolipids and gangliosides of established, L-cell-derived murine fibroblast lines and their low- and high-tumorigenic hybrids were studied.

On neutral fucoglycolipids having long, branched carbohydrate chains: H-active and I-active glycosphingolipids of human erythrocyte membranes

H-Active ceramide heptasaccharide (H2-glycolipid) and ceramide decasaccharide (H3-glycolipid) were isolated from blood group O human erythrocyte membranes. Their structures have been determined by conventional methylation analysis, enzymatic degradation, and direct total mass spectrometry of the enzymatic degradation products after permethylation and reduction with sodium bis(2-methoxyethoxy)aluminum hydride. The branched sugar residue in the structure of H3-glycolipid was unambiguously determined by a new method with the combination of enzymatic degradation and comparison of the total mass spectrogram of the reduced product of the enzyme-degraded compounds. The proposed structures are as follows: (see article) The fourth component of H-active glycolipid (H4-glycolipid) was also isolated in chromatographically heterogenous form, but chemical analysis and methylation study indicate heterogeneity of the fraction. Both H3- and H4-glycolipids inhibit I-hemagglutination, whereas H1- and H2-glycolipids do not inhibit I-hemagglutination.

Altered growth behavior of malignant cells associated with changes in externally labeled glycoprotein and glycolipid

By use of galactose oxidase (EC 1.1.3.9), followed by reduction with tritiated sodium borohydride, the surface structures of transformed 3T3 and NIL cells, under ordinary growth conditions, were characterized by (i) deletion of the normally existing glycoprotein label and (ii) appearance or increase of a new glycoprotein label. NIL cells had a galactoprotein label with molecular weight 200,000 that was deleted in NIL cells transformed by polyoma virus. 3T3 cells had a glycoprotein label with molecular weight of 30,000 that was lost after transformation. Glycoproteins of transformed 3T3 cells, with molecular weight 105,000, and those of transformed NIL cells, with molecular weight 85,000, were not labeled in normal confluent cells, but became labeled after trypsin treatment. The label in glycolipids was quantitatively different in normal and transformed cells. The labeling pattern in glycoprotein and glycolipids of transformed NIL and 3T3 cells became similar to that of nontransformed cells when contact responses of transformed cells became conspicuous when cells were cultured in the presence of dextran sulfate or dibutyryl cyclic adenosine monophosphate, or in medium in which glucose was replaced with galactose.

Quantitative isolation of total glycosphingolipids from animal cells

The quantitative isolation of total glycosphingolipids from crude lipid extracts without contamination from other lipid classes is described. The method consists of (a) acetylation of total lipids with pyridine and acetic anhydride, (b) separation of acetylated glycolipids from nonglycolipids on a magnesia-silica gel (Florisil) column, and (c) deacetylation of glycolipid in chloroform-methanol-sodium methoxide. This method is useful for determination of microgram quantities of glycolipids derived from less than 1 ml of packed cells.

Glycolipids of hamster fibroblasts and derived malignant-transformed cell lines

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Release of carbohydrates from sphingoglycolipid by osmium-catalyzed periodate oxidation followed by treatment with mild alkali

The carbohydrate moiety of sphingoglycolipid, after preliminary acetylation, can be released by periodate oxidation catalyzed by a trace amount of osmium tetroxide, followed by alkaline treatment. Cerebroside, lactosyl ceramide, hematoside, globoside, and gangliosides were degraded to yield, respectively, galactose, lactose, sialyl lactose, a tetrasaccharide, and various oligosaccharides containing sialic acid. Oligosaccharides were separated by paper chromatography and paper electrophoresis. The procedure is useful for characterizing micromolar amounts of sphingoglycolipids.