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‣ Gangliosides Are Important for the Preservation of the Structure and Organization of RBL-2H3 Mast Cells

SOUZA, Adriana Maria Mariano Silveira e; TRINDADE, Edvaldo S.; JAMUR, Maria Celia; OLIVER, Constance
Fonte: HISTOCHEMICAL SOC INC Publicador: HISTOCHEMICAL SOC INC
Tipo: Artigo de Revista Científica
Português
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Gangliosides are known to be important in many biological processes. However, details concerning the exact function of these glycosphingolipids in cell physiology are poorly understood. in this study, the role of gangliosides present on the surface of rodent mast cells in maintaining cell structure was examined using RBL-2H3 mast cells and two mutant cell lines (E5 and D1) deficient in the gangliosides, GM(1) and the alpha-galactosyl derivatives of the ganglioside GD(1b). The two deficient cell lines were morphologically different from each other as well as from the parental RBL-2H3 cells. Actin filaments in RBL-2H3 and E5 cells were under the plasma membrane following the spindle shape of the cells, whereas in D1 cells, they were concentrated in large membrane ruffles. Microtubules in RBL-2H3 and E5 cells radiated from the centrosome and were organized into long, straight bundles. The bundles in D1 cells were thicker and organized circumferentially under the plasma membrane. The endoplasmic reticulum, the Golgi complex, and the secretory granule matrix were also altered in the mutant cell lines. These results suggest that the mast cell-specific alpha-galactosyl derivatives of ganglioside GD(1b) and GM(1) are important in maintaining normal cell morphology. (J Histochern Cytochem 58:83-93...

‣ GD1b-Derived Gangliosides Modulate Fc epsilon RI Endocytosis in Mast Cells

MAZUCATO, Vivian Marino; SOUZA, Adriana Maria Mariano Silveira e; NICOLETTI, Liliana Martos; JAMUR, Maria Celia; OLIVER, Constance
Fonte: SAGE PUBLICATIONS LTD Publicador: SAGE PUBLICATIONS LTD
Tipo: Artigo de Revista Científica
Português
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The role of the mast cell-specific gangliosides in the modulation of the endocytic pathway of Fc epsilon RI was investigated in RBL-2H3 cells and in the ganglioside-deficient cell lines, E5 and D1. MAb BC4, which binds to the alpha subunit of Fc epsilon RI, was used in the analysis of receptor internalization. After incubation with BC4-FITC for 30 min, endocytic vesicles in RBL-2H3 and E5 cells were dispersed in the cytoplasm. After 1 hr, the endocytic vesicles of the RBL-2H3 cells had fused and formed clusters, whereas in the E5 cells, the fusion was slower. In contrast, in D1 cells, the endocytic vesicles were smaller and remained close to the plasma membrane even after 3 hr of incubation. When incubated with BC4-FITC and subsequently imunolabeled for markers of various endocytic compartments, a defect in the endocytic pathway in the E5 and D1 cells became evident. In the D1 cells, this defect was observed at the initial steps of endocytosis. Therefore, the ganglioside derivatives from GD1b are important in the endocytosis of Fc epsilon RI in mast cells. Because gangliosides may play a role in mast cell-related disease processes, they provide an attractive target for drug therapy and diagnosis. (J Histochem Cytochem 59:428-440, 2011); CAPES (Coordenacao de Aperfeicoamento de Pessoa de Nivel Superior); FAEPA (Fundacao de Apoio ao Ensino...

‣ Experimental surgery of the facial nerve. Assessment of the intraperitoneal use of exogenous gangliosides

Montovani, J. C.; Prado, R. G.; Bacchi, C. E.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 163-167
Português
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Compression and section of the facial nerve were performed in 48 rats in order to study the anatomopathological alterations occurring after daily intraperitoneal injections of 100 mg of exogenous gangliosides (Sinaxial®) for 45, 90, 180 days. In groups submitted to nerve compression, the histopathological changes were discrete and in the 180-day subgroups the nerve was practically normal. In animals submitted to section and neurorrhaphy there was formation of an amputation neuroma, a granuloma around the suture, axonal unstructuration and inter and perineural fibrosis. No significant differences were observed between the groups submitted or not to injection of exogenous gangliosides, indicating that the major factors involved in the quality of nerve regeneration were the technique and the formation of fibrosis and of an amputation neuroma.

‣ Modulação da expressão de fatores de regeneração/crescimento de ilhotas pancreáticas e tecido acinar pancreático em camundongos NOD (non-obese diabetic) tratados com gangliosídeos = : Modulation of regeneration/growth factors expression in pancreatic exocrine and endocrine tissue of NOD (non-obese diabetic) mice treated with gangliosides; Modulation of regeneration/growth factors expression in pancreatic exocrine and endocrine tissue of NOD (non-obese diabetic) mice treated with gangliosides

Luís Guilherme Stivanin Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 13/07/2012 Português
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Empregando as linhagens de camundongos NOD (non-obese diabetic) de desenvolvimento espontâneo do diabetes mellitus tipo 1 e BALB/c como linhagem controle, administrou-se exogenamente gangliosídeo GM1, mistura de gangliosídeos (GGs) (GM1 21%, GD1a 40%, GD1b 16%, GT1b 19%) e solução salina (0,9% NaCl) estéril da 4ª à 28ª semana de vida. Os efeitos da administração dos gangliosídeos sobre a frequência da manifestação do diabetes, índice de insulite, imunofenotipificação e atividade apoptótica de células presentes em ilhotas pancreáticas de NOD foram verificados por meio de análise glicêmica semanal, técnica colorimétrica com Eosina-Hematoxilina, imunofluorescência e TUNEL. A expressão gênica e os níveis séricos de insulina, além das expressões celular protéica e gênica dos fatores de regeneração GLP-1, PDX-1 e Ngn3 nos tecidos pancreáticos de BALB/c e NOD foram analisados por meio de ELISA, imunofluorescência e RT-PCR em tempo real. Após 28 semanas de tratamento, pôde-se verificar que os animais tratados com GM1 reduziram o diabetes de 70% observado nos animais controle salina, para 38%. Os animais tratados com GGs não apresentaram diabetes. O índice de insulite estava diminuído nos animais tratados com GM1 (p=0.09)...

‣ The 9-O-acetyl GD3 gangliosides are expressed by migrating chains of subventricular zone neurons in vitro

Miyakoshi,L.M.; Mendez-Otero,R.; Hedin-Pereira,C.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2001 Português
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Neurons from the anterior subventricular zone (SVZ) of the cerebral cortex migrate tangentially to become interneurons in the olfactory bulb during development and in adult rodents. This migration was defined as neuronophilic, independent of a radial glial substrate. The cortical SVZ and the rostral migratory stream to the olfactory bulb were shown to be rich in 9-O-acetyl GD3 gangliosides (9-O-acGD3), which have been previously shown to be implicated in gliophilic migration in the rodent cerebral cortex and cerebellum. In the present study, we performed SVZ explant cultures using rats during their first postnatal week to analyze the expression of these gangliosides in chain migration of neuronal precursors. We characterized migrating chains of these neuroblasts through morphological analysis and immunocytochemistry for the neural cell adhesion molecule. By using the Jones monoclonal antibody which binds specifically to 9-O-acGD3 we showed that migrating chains from the SVZ explants express 9-O-acGD3 which is distributed in a punctate manner in individual cells. 9-O-acGD3 is also present in migrating chains that form in the absence of radial glia, typical of the neuronophilic chain migration of the SVZ. Our data indicate that 9-O-acetylated gangliosides may participate in neuronophilic as well as gliophilic migration.

‣ Inhibition of mouse and rat lymphoproliferation by gangliosides

MONTERO,EFS; CASTRO,LC; BARBIERI,CL; TAHA,MO; NIGRO,AJT
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2000 Português
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Our previous study have demonstrated that Glycosphingolipids (GSLs) have an immunosuppressive effect on murine lymphoproliferation and IL-2 production. In the present study we examined the effect of a pool of Gangliosides (Gang) on spleen lymphocyte proliferation from either isogeneic strains of Wistar rats or BALB/c mice. Two hundred-fifty grams adult female isogeneic Wistar rats and 8-week-old BALB/c mice were used. The animals were sacrificed and the spleen harvested aseptically for cellular assays. Spleen cells suspensions were obtained by homogenization in RPMI 1640 with a loose tissue grinder. After washing, the cells were suspended in RPMI 1640 supplemented. Cell viability was measured by Trypan blue exclusion. Cells were cultured in triplicate using increasing concentrations of Gang (1; 2; 5; 10; 15; 20 mug/well) and in the presence of Concanavalin A. The cells were incubated for 48 hours and were pulsed with [³H] thymidine 18 hours prior to harvesting on glass fiber paper for counting in a beta-counter. Data were presented as rate of inhibition, as previously described. At concentrations 1 and 2 mug/well, Gang stimulated lymphoproliferation (30% and 50%, rats and mice respectively), while at concentration from 5 to 20 mug/well an increasing inhibition was observed for spleen cells from both mouse and rat (from 40% up to 80%). In preliminary studies we observed inhibition of mixed lymphocyte reaction on spleen cells from rats treated with Gang for 10 days (data not shown). Our data suggest that Gang may be investigated as a immunosuppressive drug in organ transplantation.

‣ Histopathological analysis of gangliosides use in peripheral nerve regeneration after axonotmesis in rats

Ribeiro,Camila Maria Beder; Vasconcelos,Belmiro Cavalcanti do Egito; Silva Neto,Joaquim Celestino da; Silva Júnior,Valdemiro Amaro da; Figueiredo,Nancy Gurgel
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2008 Português
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PURPOSE: To analyze the action of gangliosides in peripheral nerve regeneration in the sciatic nerve of the rat. METHODS: The sample was composed of 96 male Wistar rats. The animals were anaesthetized and, after identification of the anaesthesic plane, an incision was made in the posterior region of the thigh, followed by skin and muscle divulsion. The right sciatic nerve was isolated and compressed for 2 minutes. Continuous suture of the skin was performed. The animals were randomly divided into two groups: the experimental group (EG), which received subcutaneous injection of gangliosides, and the control group (CG), which received saline solution (0.9%) to mimic the effects of drug administration. RESULTS: No differences were observed between the experimental and control groups evaluated on the eighth day of observation. At 15 and 30 days the EG showed an decrease in Schwann cell activity and an apparent improvement in fibre organization; at 60 days, there was a slight presence of Schwann cells in the endoneural space and the fibres were organized, indicating nerve regeneration. At 15 and 30 days, the level of cell reaction in the CG had diminished, but there were many cells with cytoplasm in activity and in mitosis; at 60 days, hyperplastic Schwann cells and mitotic activity were again observed...

‣ Interaction of Fibroblast Growth Factor-2 (FGF-2) with Free Gangliosides: Biochemical Characterization and Biological Consequences in Endothelial Cell Cultures

Rusnati, Marco; Tanghetti, Elena; Urbinati, Chiara; Tulipano, Giovanni; Marchesini, Sergio; Ziche, Marina; Presta, Marco
Fonte: The American Society for Cell Biology Publicador: The American Society for Cell Biology
Tipo: Artigo de Revista Científica
Publicado em /02/1999 Português
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Exogenous gangliosides affect the angiogenic activity of fibroblast growth factor-2 (FGF-2), but their mechanism of action has not been elucidated. Here, a possible direct interaction of sialo-glycolipids with FGF-2 has been investigated. Size exclusion chromatography demonstrates that native, but not heat-denatured, 125I-FGF-2 binds to micelles formed by gangliosides GT1b, GD1b, or GM1. Also, gangliosides protect native FGF-2 from trypsin digestion at micromolar concentrations, the order of relative potency being GT1b > GD1b > GM1 = GM2 = sulfatide > GM3 = galactosyl-ceramide, whereas asialo-GM1, neuraminic acid, and N-acetylneuramin-lactose were ineffective. Scatchard plot analysis of the binding data of fluorochrome-labeled GM1 to immobilized FGF-2 indicates that FGF–2/GM1 interaction occurs with a Kd equal to 6 μM. This interaction is inhibited by the sialic acid-binding peptide mastoparan and by the synthetic fragments FGF-2(112–129) and, to a lesser extent, FGF-2(130–155), whereas peptides FGF-2(10–33), FGF-2(39–59), FGF-2(86–96), and the basic peptide HIV-1 Tat(41–60) were ineffective. These data identify the COOH terminus of FGF-2 as a putative ganglioside-binding region. Exogenous gangliosides inhibit the binding of 125I-FGF-2 to high-affinity tyrosine-kinase FGF-receptors (FGFRs) of endothelial GM 7373 cells at micromolar concentrations. The order of relative potency was GT1b > GD1b > GM1 > sulfatide a = sialo-GM1. Accordingly...

‣ Specific binding of Haemophilus influenzae to minor gangliosides of human respiratory epithelial cells.

Fakih, M G; Murphy, T F; Pattoli, M A; Berenson, C S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1997 Português
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Gangliosides are sialylated glycosphingolipids that serve as receptors for various bacteria. To investigate endogenous gangliosides of human respiratory epithelial cells as potential receptors for Haemophilus influenzae, three strains, including nontypeable H. influenzae (NTHI) 1479, and isogenic fimbriated (f+) and nonfimbriated (f0) H. influenzae type b 770235, were 3H labeled and overlaid on two-dimensional thin-layer chromatography (TLC) plates containing either purified HEp-2 gangliosides or murine brain gangliosides. NTHI 1479 bound exclusively to two distinct minor ganglioside doublets, with mobilities near that of GM1. These minor gangliosides comprised only 14.2 and 9.4% of the total, respectively. NTHI 1479 also bound to a distinct ganglioside of human macrophages whose chromatographic mobilities closely resemble those of one of the NTHI-binding gangliosides of HEp-2 cells. H. influenzae type b 770235 f+ and f0 each bound to a different minor HEp-2 ganglioside doublet, with proportionately weaker affinity for a major ganglioside doublet. Remarkably, none of the three strains bound to any murine brain gangliosides. Moreover, when 80 to 90% of sialic acid residues were enzymatically removed from HEp-2 gangliosides, NTHI 1479 binding was proportionately impaired...

‣ Specific gangliosides function as host cell receptors for Sendai virus.

Markwell, M A; Svennerholm, L; Paulson, J C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1981 Português
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The ability of specific gangliosides to function as host cell receptors for Sendai virus was investigated by using Madin-Darby bovine kidney cells which become resistant to infection upon treatment with Vibrio cholerae sialidase. Sialidase-treated cells were incubated for 20 min at 37 degrees C with individual, highly purified gangliosides containing homogeneous carbohydrate moieties and then inoculated with virus for 10 min. Susceptibility of the cells to infection was monitored by hemagglutination titer of the virus produced 48 hr after inoculation. Incubation of the cells with gangliosides containing the sequence NeuAc alpha 2,3Gal beta 1,3GalNAc (i.e., GD1a, GT1b, and GQ1b) fully restored susceptibility to infection to the cells. However, the ganglioside GQ1b in which the sequence ends with two sialic acids in a NeuAc alpha 2,8NeuAc linkage instead of a single sialic acid as in GD1a and GT1b, was effective as a receptor at a concentration 1/100th that of any of the other gangliosides tested. Incubation with gangliosides similar in structure to GD1a, GT1b, and GQ1b but lacking the sialic acid attached to the terminal galactose (i.e., GM1 and GD1b) had no effect. The results from control experiments in which gangliosides were incubated at 0 degrees C with cells or in which trypsin was used to remove gangliosides adsorbed to cells were consistent with the premise that the gangliosides must actually insert into the cellular membrane to function as Sendai virus receptors. Addition of 4 X 10(6) molecules of 14C-labeled GD1a per cell made the cells fully susceptible to infection. Analysis of the ganglioside content of cell membranes showed that gangliosides GD1a...

‣ Gangliosides are potent immunosuppressors of IL-2-mediated T-cell proliferation in a low protein environment.

Lu, P; Sharom, F J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1995 Português
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Gangliosides are immunosuppressive to many classes of immune cells, and shedding of these glycosphingolipids by tumour cells may regulate immune responses in cancer, and protect tumours from host immune destruction. One mechanism of immunosuppression by gangliosides in vitro involves competition with interleukin-2 receptors (IL-2R) for binding of IL-2. Previous studies on inhibition of IL-2-mediated events by gangliosides have been conducted in the presence of high levels of fetal bovine serum (FBS). However, gangliosides shed by tumours in vivo will encounter immune cells in the low protein microenvironment of the tissue fluid. In order to better mimic physiological conditions, we have examined immunosuppression by gangliosides towards IL-2-dependent HT-2 cells in a low serum-low protein medium. The ability of gangliosides to inhibit IL-2-stimulated DNA synthesis in HT-2 increased dramatically as the serum concentration in the culture medium was decreased; the 50% inhibitory concentration (IC50) value for GM1 was 13 microM under low serum conditions, 14-fold lower than the value obtained in 10% FBS. Further investigation revealed that the mechanism of immunosuppression by gangliosides in low serum-low protein medium involved interference with the IL-2/IL-2R system. Ganglioside-mediated inhibition was dependent on the continued presence of the glycolipids during the first few hours after IL-2 stimulation...

‣ Gangliosides interact with interleukin-4 and inhibit interleukin-4-stimulated helper T-cell proliferation.

Chu, J W; Sharom, F J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1995 Português
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Gangliosides are potent immunosuppressive agents in vitro, and gangliosides shed from tumours in vivo may play an important role in the escape of tumours from immune destruction. We have investigated the effect of gangliosides on interleukin-4 (IL-4)-mediated processes in the murine helper T-cell line HT-2. Various gangliosides inhibited IL-4-stimulated DNA synthesis in HT-2 with IC50 values in the range 26-60 micrograms/ml. However, the proliferation of four lymphokine-independent cell lines was unaffected by 500 micrograms/ml gangliosides, as was the IL-1-stimulated secretion of IL-2 by EL-4 NOB-1 cells. Gangliosides were highly effective inhibitors when added to G0-G1-synchronized HT-2 cells during the first 6 hr after IL-4 stimulation, indicating that they act early in the IL-4 signalling pathway. High levels of exogenous IL-4 completely reversed inhibition of proliferation by gangliosides, which suggests that gangliosides compete with cellular IL-4 receptors for available lymphokine. Receptor-binding experiments confirmed that gangliosides blocked binding of [125I]IL-4 to receptors on intact HT-2 cells in a dose-dependent fashion. Gel-filtration fast protein liquid chromatography (FPLC) demonstrated that [125I]IL-4 co-eluted with ganglioside micelles after co-incubation before chromatography...

‣ Gangliosides inhibit T-lymphocyte proliferation by preventing the interaction of interleukin-2 with its cell surface receptors.

Chu, J W; Sharom, F J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1993 Português
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Gangliosides are known to be actively shed from tumour cell membranes, and increased levels of circulating gangliosides may cause tumour-induced T-lymphocyte immunosuppression in vivo by interfering with the actions of interleukin-2 (IL-2). We have investigated the effect of gangliosides on the interaction of IL-2 with its cell surface receptors (IL-2R). Gangliosides inhibited IL-2-stimulated proliferation in synchronized populations of the IL-2-dependent cell lines CTLL-2 and HT-2. The immunosuppressive effect was most effective when gangliosides were added during the first 4 hr after IL-2-stimulation, indicating that they acted early in the IL-2 signalling pathway. Inhibition could be completely overcome by exogenous IL-2, suggesting that gangliosides inhibited growth solely by competing with IL-2R for available IL-2. In support of this proposal, gangliosides induced a concomitant dose-dependent decrease in binding of [125I]IL-2 to high-, medium- and low-affinity IL-2R. Ganglioside-treated cells recovered their high-affinity [125I]IL-2 binding after washing. The glycolipids also prevented chemical cross-linking of [125I]IL-2 to the p55/p75 complex, as well as to both IL-2R alpha (p55) and IL-2R beta (p75) independently. A thin-layer chromatography overlay technique was used to demonstrate that IL-2 binds directly to gangliosides...

‣ Incorporation of fluorescent gangliosides into human fibroblasts: mobility, fate, and interaction with fibronectin

Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/08/1984 Português
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Rhodamine- and fluorescein-labeled gangliosides were used as probes to investigate the distribution, dynamics, and fate of plasma membrane- bound gangliosides on cultured human fibroblasts. When sparse cultures of fibroblasts were incubated with the fluorescent ganglioside derivatives, their surfaces became highly fluorescent. The fluorescent gangliosides were taken up by the cells in a time- and temperature- dependent manner and were not removed from the cell surface by trypsin or serum. Thus, the gangliosides appeared to be stably incorporated into the lipid bilayer of the plasma membrane. Fluorescent photobleaching recovery measurements showed that the inserted gangliosides were free to diffuse in the plane of the membrane with a high diffusion coefficient of approximately 10(-8) cm2/s. When the ganglioside-treated cells were washed and incubated in fresh medium, the surface gangliosides became internalized with time, and localized in the perinuclear region of the fibroblasts. In dense cultures of fibroblasts, a large fraction of the fluorescent gangliosides were organized in a fibrillar network and were immobile on the time scale of fluorescent photobleaching recovery measurements. Using antifibronectin antibodies and indirect immunofluorescence...

‣ Direct visualization of redistribution and capping of fluorescent gangliosides on lymphocytes

Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/11/1984 Português
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Fluorescent derivatives of gangliosides were prepared by oxidizing the sialyl residues to aldehydes and reacting them with fluorescent hydrazides. When rhodaminyl gangliosides were incubated with lymphocytes, the cells incorporated them in a time- and temperature- dependent manner. Initially, the gangliosides were evenly distributed on the cell surface but were redistributed into patches and caps by antirhodamine antibodies. When the cells were then stained with a second antibody or protein A labeled with fluorescein, the fluorescein stain revealed the coincident movement of both the gangliosides and the antirhodamine antibodies. When the cells were treated with both rhodamine and Lucifer yellow CH-labeled gangliosides, the antirhodamine antibodies induced patching and capping of both fluorescent gangliosides but had no effect on cells incubated only with Lucifer yellow CH-labeled gangliosides. In addition, capping was observed on cells exposed to cholera toxin, antitoxin antibodies, and rhodamine- labeled protein A, indirectly showing the redistribution of endogenous ganglioside GM1, the cholera toxin receptor. By incorporating Lucifer yellow CH-labeled GM1 into the cells and inducing capping as above, we were able to demonstrate directly the coordinate redistribution of the fluorescent GM1 and the toxin. When the lymphocytes were stained first with Lucifer yellow CH-labeled exogenous ganglioside GM3...

‣ Fibrillar organization of fibronectin is expressed coordinately with cell surface gangliosides in a variant murine fibroblast

Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/05/1986 Português
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NCTC 2071A cells, a line of transformed murine fibroblasts, grow in serum-free medium, are deficient in gangliosides, synthesize fibronectin, but do not retain and organize it on the cell surface. When the cells are exposed to exogenous gangliosides, fibrillar strands of fibronectin become attached to the cell surface. A morphologically distinct variant of NCTC 2071A cells was observed to both retain cell surface fibronectin and organize it into a fibrillar network when the cells were stained with anti-fibronectin antibodies and a fluorescent second antibody. A revertant cell type appeared to resemble the parental NCTC 2071A cells in terms of morphology and fibronectin organization. All three cell types were subjected to mild NaIO4 oxidation and reduction with KB3H4 of very high specific radioactivity in order to label the sialic acid residues of surface gangliosides. The variant had much more surface gangliosides than the parental, particularly more complex gangliosides corresponding to GM1 and GD1a. The surface gangliosides of the revertant were intermediate between the parental and the variant. By using sialidase, which hydrolyzes GD1a to GM1, and 125I-labeled cholera toxin, which binds specifically to GM1, the identity and levels of these gangliosides were confirmed in the three cell types. When variant cells were exposed to sialidase for 2 d...

‣ Lack of specificity of brain gangliosides in the modulation of lymphocyte activation.

Ryan, J. L.; Inouye, L. N.; Gobran, L.; Yohe, W. B.; Yohe, H. C.
Fonte: Yale Journal of Biology and Medicine Publicador: Yale Journal of Biology and Medicine
Tipo: Artigo de Revista Científica
Publicado em //1985 Português
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A potential role for glycolipid gangliosides to act as immunomodulating agents has been suggested. Most studies have employed brain gangliosides. We have systematically investigated highly purified murine brain gangliosides for their ability to modulate lymphocyte activation. All sialic acid classes of ganglioside inhibited lipopolysaccharide (LPS)-induced antibody secretion and all polysialated gangliosides inhibited LPS-induced DNA synthesis. Monosialated gangliosides had no effect on DNA synthesis induced by LPS. 8-BrcGMP-induced DNA synthesis was also inhibited, suggesting that a negative signal was delivered to B lymphocytes by co-cultivation with exogenous gangliosides. The lack of specificity with respect to sialic acid class observed in these studies suggests that further investigation of an immunomodulatory role for gangliosides focus on endogenous lymphocyte gangliosides.

‣ Differential Distribution of Major Brain Gangliosides in the Adult Mouse Central Nervous System

Vajn, Katarina; Viljetić, Barbara; Degmečić, Ivan Večeslav; Schnaar, Ronald L.; Heffer, Marija
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 30/09/2013 Português
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Gangliosides - sialic acid-bearing glycolipids - are major cell surface determinants on neurons and axons. The same four closely related structures, GM1, GD1a, GD1b and GT1b, comprise the majority of total brain gangliosides in mammals and birds. Gangliosides regulate the activities of proteins in the membranes in which they reside, and also act as cell-cell recognition receptors. Understanding the functions of major brain gangliosides requires knowledge of their tissue distribution, which has been accomplished in the past using biochemical and immunohistochemical methods. Armed with new knowledge about the stability and accessibility of gangliosides in tissues and new IgG-class specific monoclonal antibodies, we investigated the detailed tissue distribution of gangliosides in the adult mouse brain. Gangliosides GD1b and GT1b are widely expressed in gray and white matter. In contrast, GM1 is predominately found in white matter and GD1a is specifically expressed in certain brain nuclei/tracts. These findings are considered in relationship to the hypothesis that gangliosides GD1a and GT1b act as receptors for an important axon-myelin recognition protein, myelin-associated glycoprotein (MAG). Mediating axon-myelin interactions is but one potential function of the major brain gangliosides...

‣ Abnormal gangliosides are localized in lipid rafts in Sanfilippo (MPS3a) mouse brain

Dawson, G.; Fuller, M.; Hemsley, K.; Hopwood, J.
Fonte: Kluwer Academic/Plenum Publ Publicador: Kluwer Academic/Plenum Publ
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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Allogenic stem cell transplantation can reduce lysosomal storage of heparan sulfate-derived oligosaccharides by up to 27 % in Sanfilippo MPS3a brain, but does not reduce the abnormal storage of sialolactosylceramide (GM3) or improve neurological symptoms, suggesting that ganglioside storage is in a non-lysosomal compartment. To investigate this further we isolated the Triton X100-insoluble at 4 °C, lipid raft (LR) fraction from a sucrose-density gradient from cerebral hemispheres of a 7 month old mouse model of Sanfilippo MPS3a and age-matched control mouse brain. HPLC/MS/MS analysis revealed the expected enrichment of normal complex gangliosides, ceramides, galatosylceramides and sphingomyelin enrichment in this LR fraction. The abnormal HS-derived oligosaccharide storage material was in the Triton X100-soluble at 4 °C fractions (8–12),whereas both GM3 and sialo[GalNAc]lactosylceramide (GM2) were found exclusively in the LR fraction (fractions 3 and 4) and were >90 % C18:0 fatty acid, suggesting a neuronal origin. Further analysis also revealed a >threefold increase in the late-endosome marker bis (monoacylglycerol) phosphate (>70 % as C22:6/22:6-BMP) in non-LR fractions 8–12 whereas different forms of the proposed BMP precursor...

‣ O papel de gangliosídeos específicos como moduladores da liberação de mediadores de mastócitos; The role of mast cell specific gangliosides in modulating mediator release

Freitas Filho, Edismauro Garcia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/03/2015 Português
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Os mastócitos são células multifuncionais do sistema imunológico que participam em diversos processos biológicos. As funções dos mastócitos estão diretamente relacionados com a sua ativação e, subsequente, liberação de mediadores químicos. Os eventos iniciais da ativação dos mastócitos e da transdução de sinais ocorrem em microdomínios lipídicos (lipid rafts) da membrana plasmática. Os gangliosídeos derivados do GD1b são constituintes dos lipid rafts de mastócitos de roedores. O intercruzamento destes gangliosídeos pelo mAb AA4, resulta na formação de agregados (caps) na superfície celular e promove uma ativação parcial dos mastócitos, sem que ocorra a desgranulação. A ativação é semelhante a observada quando os FcRIs são intercruzados por antígenos multivalentes ligados a IgEs, mas neste caso ocorre a desgranulação. O presente estudo tem como objetivo caracterizar o papel dos gangliosídeos derivados do GD1b na liberação de mediadores de mastócitos da linhagem RBL-2H3. O intercruzamento dos gangliosídeos derivados do GD1b resulta na ativação dos fatores de transcrição NFAT e NFB e esta ativação é mediada pela proteína quinase Syk. A ativação destes fatores de transcrição resulta na liberação de mediadores neo-sintetizados...