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Distribuição de glicoproteinas no ligamento periodontal e no periodonto relacionado ao esmalte do incisivo de camundongo, em diferentes condições funcionais : estudo radioautografico pela incorporação de [3H]-Fucose

Monica Machado Duarte
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em //2004 PT
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Para analisar se o aumento da quantidade de proteínas não colágenas no ligamento periodontal de incisivos de ratos desimpedidos (hipofuncionais) está relacionado com o aumento da velocidade de erupção que ocorre nestes dentes, utilizamos a [3H]-fucose, precursor específico para glicoproteínas, e, através da radioautografia, observamos sua incorporação nos tecidos periodontais de incisivos de camundongos. Camundongos fêmeas foram divididos em três grupos com 4 animais cada. Em dois grupos o incisivo inferior esquerdo foi cortado à altura da papila gengival,tornando-o hipofuncional enquanto o contralateral direito tornou-se hiperfuncional. No terceiro grupo os incisivos foram mantidos intactos e portanto normofuncionais. A [3H]-fucose foi injetada na veia caudal no seguinte esquema: 1) no primeiro grupo, 1 dia após a instalação da alteração funcional; 2) no 2o grupo 7 dias após a desoclusão do incisivo esquerdo (assim mantida com cortes a cada 48 horas) e 3) no grupo normofuncional no mesmo tempo que no grupo 2. Os camundongos foram perfundidos com fixador de Karnovsky, em grupos de dois, 8 e 96 horas após a injeção do precursor radioativo. As hemimandíbulas foram removidas, descalcificadas, divididas em segmentos transversais e incluídas em araldite. Cortes de 1mm das regiões relacionadas à crista alveolar...

Radioactive fucose as a tool for studying glycoprotein secretion

Haddad,A.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/1998 EN
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The efficiency and reliability of radioactive fucose as a specific label for newly synthesized glycoproteins were investigated. Young adult male rabbits were injected intravitreally with [3H]-fucose, [3H]-galactose, [3H]-mannose, N-acetyl-[3H]-glucosamine or N-acetyl-[3H]-mannosamine, and killed 40 h after injection. In another series of experiments rabbits were injected with either [3H]-fucose or several tritiated amino acids and the specific activity of the vitreous proteins was determined. Vitreous samples were also processed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and histological sections of retina, ciliary body and lens (the eye components around the vitreous body) were processed for radioautography. The specific activity (counts per minute per microgram of protein) of the glycoproteins labeled with [3H]-fucose was always much higher than that of the proteins labeled with any of the other monosaccharides or any of the amino acids. There was a good correlation between the specific activity of the proteins labeled by any of the above precursors and the density of the vitreous protein bands detected by fluorography. This was also true for the silver grain density on the radioautographs of the histological sections of retina...

The MUR1 gene of Arabidopsis thaliana encodes an isoform of GDP-d-mannose-4,6-dehydratase, catalyzing the first step in the de novo synthesis of GDP-l-fucose

Bonin, Christopher P.; Potter, Ian; Vanzin, Gary F.; Reiter, Wolf-Dieter
Fonte: The National Academy of Sciences of the USA Publicador: The National Academy of Sciences of the USA
Tipo: Artigo de Revista Científica
Publicado em 04/03/1997 EN
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GDP-l-fucose is the activated nucleotide sugar form of l-fucose, which is a constituent of many structural polysaccharides and glycoproteins in various organisms. The de novo synthesis of GDP-l-fucose from GDP-d-mannose encompasses three catalytic steps, a 4,6-dehydration, a 3,5-epimerization, and a 4-reduction. The mur1 mutant of Arabidopsis is deficient in l-fucose in the shoot and is rescued by growth in the presence of exogenously supplied l-fucose. Biochemical assays of the de novo pathway for the synthesis of GDP-l-fucose indicated that mur1 was blocked in the first nucleotide sugar interconversion step, a GDP-d-mannose-4,6-dehydratase. An expressed sequence tag was identified that showed significant sequence similarity to proposed bacterial GDP-d-mannose-4,6-dehydratases and was tightly linked to the mur1 locus. A full-length clone was isolated from a cDNA library, and its coding region was expressed in Escherichia coli. The recombinant protein exhibited GDP-d-mannose-4,6-dehydratase activity in vitro and was able to complement mur1 extracts in vitro to complete the pathway for the synthesis of GDP-l-fucose. All seven mur1 alleles investigated showed single point mutations in the coding region for the 4,6-dehydratase, confirming that it represents the MUR1 gene.

D-arabinose metabolism in Escherichia coli B: induction and cotransductional mapping of the L-fucose-D-arabinose pathway enzymes.

Elsinghorst, E A; Mortlock, R P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1988 EN
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D-Arabinose is degraded by Escherichia coli B via some of the L-fucose pathway enzymes and a D-ribulokinase which is distinct from the L-fuculokinase of the L-fucose pathway. We found that L-fucose and D-arabinose acted as the apparent inducers of the enzymes needed for their degradation. These enzymes, including D-ribulokinase, appeared to be coordinately regulated, and mutants which constitutively synthesized the L-fucose enzymes also constitutively synthesized D-ribulokinase. In contrast to D-arabinose-positive mutants of E. coli K-12, in which L-fuculose-1-phosphate and D-ribulose-1-phosphate act as inducers of the L-fucose pathway, we found that these intermediates did not act as inducers in E. coli B. To further characterize the E. coli B system, some of the L-fucose-D-arabinose genes were mapped by using bacteriophage P1 transduction. A transposon Tn10 insertion near the E. coli B L-fucose regulon was used in two- and three-factor reciprocal crosses. The gene encoding D-ribulokinase, designated darK, was found to map within the L-fucose regulon, and the partial gene order was found to be Tn10-fucA-darK-fucI-fucK-thyA.

Isolation of a mutation resulting in constitutive synthesis of L-fucose catabolic enzymes.

Bartkus, J M; Mortlock, R P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1986 EN
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A ribitol-positive transductant of Escherichia coli K-12, JM2112, was used to facilitate the isolation and identification of mutations affecting the L-fucose catabolic pathway. Analysis of L-fucose-negative mutants of JM2112 enabled us to confirm that L-fucose-1-phosphate is the apparent inducer of the fucose catabolic enzymes. Plating of an L-fuculokinase-negative mutant of JM2112 on D-arabinose yielded an isolate containing a second fucose mutation which resulted in the constitutive synthesis of L-fucose permease, isomerase, and kinase. This constitutive mutation differs from the constitutive mutation described by Chen et al. (J. Bacteriol. 159:725-729, 1984) in that it is tightly linked to the fucose genes and appears to be located in the gene believed to code for the positive activator of the L-fucose genes.

Natural and altered induction of the L-fucose catabolic enzymes in Klebsiella aerogenes.

Saint Martin, E J; Mortlock, R P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1976 EN
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Mutants of Klebsiella aerogenes W70 were isolated that had gained the ability to utilize the uncommon pentose D-arabinose as their sole source of carbon and energy. In contrast to the D-arabinose-negative, parent strain, these mutants were found to be either constitutive for certain enzymes of the L-fucose catabolic pathway or inducible for such enzymes when incubated in the presence of D-arabinose. The mutants used L-fucose isomerase to convert D-arabinose to D-ribulose, which is an intermediate and inducer of the ribitol catabolic pathway. The D-ribulokinase of the ribitol pathway was then induced. This enzyme catalyzed the phosphorylation of D-ribulose at the 5-carbon position. Mutants that were negative for D-ribulokinase could still dissimilate D-arabinose slowly by using all three enzymes, the isomerase, kinase, and aldolase, of the L-fucose pathway. Using condition negative mutants, we were able to demonstrate that the natural induction of the L-fucose pathway enzymes by L-fucose required the activity of a functional L-fucose isomerase and a functional L-fuculokinase but not an L-fuculose-1-phosphate aldolase. A metabolic intermediate, L-fuculose-1-phosphate, was thereby shown to be a probable inducer of at least the isomerase and kinase of the L-fucose catabolic pathway. Similar experiments...

Disruption of the fucose pathway as a consequence of genetic adaptation to propanediol as a carbon source in Escherichia coli.

Hacking, A J; Lin, E C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1976 EN
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In Escherichia coli, L-fucose is dissimilated via an inducible pathway mediated by L-fucose permease, L-fucose isomerase, L-fucose kinase, and L-fuculose 1-phosphate aldolase. The last enzyme cleaves the six-carbon substrate into dihydroxyacetone phosphate and L-lactaldehyde. Aerobically, lactaldehyde is oxidized to L-lactate by a nicotinamide adenine dinucleotide (NAD)-linked dehydrogenase. Anaerobically, lactaldehyde is reduced by an NADH-COUPLED REDUCTASE TO L-1,2-propanediol, which is lost into the medium irretrievably, even when oxygen is subsequently introduced. Propanediol excretion is thus the end result of a dismutation that permits further anaerobic metabolism of dihydroxy-acetone phosphate. A mutant selected for its ability to grow aerobically on propanediol as a carbon and energy source was reported to produce lactaldehyde reductase constitutively and at high levels, even aerobically. Under the new situation, this enzyme serves as a propanediol dehydrogenase. It was also reported that the mutant had lost the ability to grow on fucose. In the present study, it is shown that in wild-type cells the full synthesis of lactaldehyde dehydrogenase requires the presence of both molecular oxygen and a small molecule effector, and the full synthesis of lactaldehyde reductase requires anaerobiosis and the presence of a small molecule effector. The failure of mutant cells to grow on fucose reflects the impairment of a regulatory element in the fucose system that prevents the induction of the permease...

Regulatory changes in the fucose system associated with the evolution of a catabolic pathway for propanediol in Escherichia coli.

Hacking, A J; Lin, E C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1977 EN
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Wild-type strains of Escherichia coli are unable to use L-1,2-propanediol as a carbon and energy source. Strain 3, a mutant selected for the ability to grow on this compound at progressively more rapid rates, synthesizes constitutively a nicotinamide adenine dinucleotide-linked propanediol oxidoreductase. This enzyme is normally synthesized during anaerobic growth on L-fucose when it functions as a lactaldehyde reductase. Propanediol, the end product of this fermentation process, escapes irretrievably into the medium. The propanediol-utilizing mutant can no longer grow on fucose in either the presence or absence of molecular oxygen. In the present study nine independent lines of propanediol-positive mutants were characterized. One mutant, strain 418, attained a propanediol growth rate close to that of strain 3 without loss of the ability to grow on fucose. In all cases examined, however, prolonged selection on propanediol did result in the emergence of fucose-negative mutants. All of these mutants had enzyme patterns similar to that of strain 3; namely, fucose permease, fucose isomerase, and fuculose kinase were noninducible, whereas fuculose 1-phosphate aldolase was constitutive. In strain 418 and in the fucose-positive predecessors of the other mutants...

Enhancement of Glutamate Release by l-Fucose Changes Effects of Glutamate Receptor Antagonists on Long-Term Potentiation in the Rat Hippocampus

Matthies, Henry; Schroeder, Helmut; Smalla, Karl-Heinz; Krug, Manfred
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em /07/2000 EN
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In previous studies l-fucose has been shown to facilitate long-term memory formation and to enhance and prolong long-term potentiation (LTP). To search for possible presynaptic or postsynaptic mechanisms that are affected by l-fucose, we examined the effect of l-fucose on (1) inhibition of LTP induction via glutamate receptors by antagonists, (2) paired-pulse facilitation, and (3) presynaptic transmitter release. Coapplication of 0.2 mm l-fucose with the competitive N-methyl-d-aspartate (NMDA) receptor antagonist, d-2-amino-5-phosphonovalerate (AP5), or coapplication of 0.2 mml-fucose in the presence of an inhibitor for class I/II metabotropic glutamate receptors, (S)-α-methyl-4-carboxyphenylglycine (MCPG), reversed LTP blockade in the CA1-region of hippocampal slices. In contrast, l-fucose had no effect on the LTP blockade by the noncompetitive NMDA ion-channel blocker (5R,10S)-(+)-5-Methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine hydrogen maleate (MK-801). Paired-pulse facilitation, which is a primarily presynaptic phenomenon of short-term plasticity, was decreased in the presence of 0.2 mm l-fucose. Furthermore, l-fucose enhanced the K+-stimulated release of [3H]-d-aspartate from preloaded hippocampal slices in a concentration-dependent manner. These observations demonstrate an influence of l-fucose on transmitter release that in turn can increase transmitter availability at postsynaptic glutamate receptors. This effect of l-fucose may contribute to the LTP facilitation seen in vitro and in vivo as well as to improvement in memory formation.

L-Fucose-terminated glycoconjugates are recognized by pinocytosis receptors on macrophages.

Shepherd, V L; Lee, Y C; Schlesinger, P H; Stahl, P D
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1981 EN
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125I-Labeled L-fucose-albumin complex and rat preputial beta-glucuronidase are rapidly cleared from plasma after intravenous infusion. L-Fucose-albumin retards the plasma clearance of beta-glucuronidase whereas D-fucose-albumin is inactive. In vitro, 125I-labeled L-fucose-albumin is taken up into rat or rabbit alveolar macrophages by receptor-mediated pinocytosis. Uptake (37 degrees C) is time-dependent, is saturable with increasing ligand concentration (Kuptake = 4.4 X 10(-8) M), and requires Ca2+. 125I-labeled D-fucose-albumin is poorly taken up. Binding (4 degrees C) is saturable and Ca2+ dependent. Binding and uptake are fully inhibited by yeast mannan. A series of neoglycoproteins, including L-fucose-albumin, were tested as inhibitors of uptake of 125I-labeled beta-glucuronidase into macrophages. The following order of potency was observed: L-Fuc = D-Man greater than GlcNAc approximately D-Glc greater than D-Xyl much greater than than D-Gal = L-Ara = D-Fuc. L-Fucose-terminated oligosaccharides coupled to bovine serum albumin also block 125I-labeled beta-glucuronidase uptake into macrophages.

Biosynthesis of the Fucose-Containing Xyloglucan Nonasaccharide by Pea Microsomal Membranes 1

Camirand, Anne; Maclachlan, Gordon
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1986 EN
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Pea microsomal membranes catalyze the transfer of [14C]fucose (Fuc) from GDP-[U-14C]fucose, with or without added unlabeled UDP-glucose (Glc), UDP-xylose (Xyl) or UDP-galactose (Gal), to an insoluble product with properties characteristic of xyloglucan. After digestion of the ethanol-insoluble pellet with Streptomyces griseus endocellulase, [14C] fucose residues occur exclusively in a fragment corresponding in size to the xyloglucan nonasaccharide, Glc4 Xyl3 Gal Fuc. This fragment contains a single labeled fucose residue per oligomer, α-linked in a terminal nonreducing position. By comparison, in incubations where GDP-[14C] fucose is absent and replaced by UDP-[3H]xylose, the maximum size of labeled oligosaccharide found following cellulase digestion of products is an octasaccharide. In the presence of both GDP-[14C]fucose and UDP-[3H]xylose, a nonasaccharide containing the two labels is produced. Fucose and xylose residues are transferred within a few minutes to acceptor molecules of molecular weight up to 300,000. Such products do not elongate detectably over 60 minutes of incubation. The data support the conclusion that the nonasaccharide subunit of xyloglucan may be generated in vitro by transfucosylation to preformed acceptor chains...

HIGHLY CONSERVED O-FUCOSE SITES HAVE DISTINCT EFFECTS ON NOTCH1 FUNCTION

Rampal, Raajit; Arboleda-Velasquez, Joseph F.; Nita-Lazar, Alexandra; Kosik, Kenneth S.; Haltiwanger, Robert S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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The extracellular domain of mouse Notch1 contains 36 tandem epidermal growth factor like (EGF) repeats, many of which are modified with O-fucose. Previous work from several laboratories has indicated that O-fucosylation plays an important role in ligand mediated Notch activation. Nonetheless, it is not clear whether all, or a subset, of the EGF repeats need to be O-fucosylated. Three O-fucose sites are invariantly conserved in all Notch homologues with 36 EGF repeats (within EGF repeats 12, 26 and 27). In order to investigate which O-fucose sites on Notch1 are important for ligand-mediated signaling, we mutated the three invariant O-fucose sites in mouse Notch1, along with several less highly conserved sites, and evaluated their ability to transduce Jagged1 and Delta1 mediated signaling in a cell-based assay. Our analysis revealed that mutation of any of the three invariant O-fucose sites resulted in significant changes in both Delta1 and Jagged1 mediated signaling, but mutations in less highly conserved sites had no detectable effect. Interestingly, mutation of each invariant site gave a distinct effect on Notch function. Mutation of the O-fucose site in EGF repeat 12 resulted in loss of Delta1 and Jagged1 signaling, while mutation of the O-fucose site in EGF repeat 26 resulted in hyperactivation of both Delta1 and Jagged1 signaling. Mutation of the O-fucose site in EGF repeat 27 resulted in faulty trafficking of the Notch receptor to the cell surface and a decreased S1 processing of the receptor. These results indicate that the most highly conserved O-fucose sites in Notch1 are important for both processing and ligand mediated signaling in the context of a cell-based signaling assay.

Role of monocyte fucose-receptors in T-cell fibronectin activity.

Donson, J; Mandy, K; Feng, Z H; Mandy, S; Brown, E J; Godfrey, H P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1991 EN
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T-cell fibronectin (FN) is a lymphokine produced by antigen- and mitogen-activated T cells that agglutinates human monocytes at femtomolar concentrations. This extreme degree of activity derives from co-operative interactions between multiple FN domains and multiple monocyte integrin protein receptors. T-cell FN, like other FN, is a glycoprotein. The role interactions between T-cell FN carbohydrate and lectin-like monocyte surface receptors play in mediating T-cell FN activity was studied by determining the ability of monosaccharides to inhibit T-cell FN activity. L-Fucose and L-rhamnose significantly inhibited T-cell FN-mediated monocyte agglutination at concentrations as low as 0.01 mM; D-glucose, D- or L-galactose, D- or L-mannose and D-fucose were not inhibitory at 10-100 mM. This inhibition appeared to be due to interference with the binding of T-cell FN fucose residues to monocyte fucose receptors since: (i) treatment of T-cell FN with alpha-L-fucosidase abolished its agglutinating activity for human monocytes, while treatment with beta-D-galactosidase or with alpha-L-fucosidase in the presence of L-fucose had no effect; (ii) treatment of monocytes with alpha-L-fucosidase did not affect their response to T-cell FN; and (iii) L-fucose or L-rhamnose did not alter the expression of monocyte integrin FN receptors under conditions where T-cell FN-mediated monocyte agglutination was completely inhibited. In vivo...

Two Pathways for Importing GDP-fucose into the Endoplasmic Reticulum Lumen Function Redundantly in the O-Fucosylation of Notch in Drosophila*

Ishikawa, Hiroyuki O.; Ayukawa, Tomonori; Nakayama, Minoru; Higashi, Shunsuke; Kamiyama, Shin; Nishihara, Shoko; Aoki, Kazuhisa; Ishida, Nobuhiro; Sanai, Yutaka; Matsuno, Kenji
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
EN
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Notch is a transmembrane receptor that shares homology with proteins containing epidermal growth factor-like repeats and mediates the cell-cell interactions necessary for many cell fate decisions. In Drosophila, O-fucosyltransferase 1 catalyzes the O-fucosylation of these epidermal growth factor-like repeats. This O-fucose elongates, resulting in an O-linked tetrasaccharide that regulates the signaling activities of Notch. Fucosyltransferases utilize GDP-fucose, which is synthesized in the cytosol, but fucosylation occurs in the lumen of the endoplasmic reticulum (ER) and Golgi. Therefore, GDP-fucose uptake into the ER and Golgi is essential for fucosylation. However, although GDP-fucose biosynthesis is well understood, the mechanisms and intracellular routes of GDP-fucose transportation remain unclear. Our previous study on the Drosophila Golgi GDP-fucose transporter (Gfr), which specifically localizes to the Golgi, suggested that another GDP-fucose transporter(s) exists in Drosophila. Here, we identified Efr (ER GDP-fucose transporter), a GDP-fucose transporter that localizes specifically to the ER. Efr is a multifunctional nucleotide sugar transporter involved in the biosynthesis of heparan sulfate-glycosaminoglycan chains and the O-fucosylation of Notch. Comparison of the fucosylation defects in the N-glycans in Gfr and Efr mutants revealed that Gfr and Efr made distinct contributions to this modification; Gfr but not Efr was crucial for the fucosylation of N-glycans. We also found that Gfr and Efr function redundantly in the O-fucosylation of Notch...

Rescue of Notch signaling in cells incapable of GDP-l-fucose synthesis by gap junction transfer of GDP-l-fucose in Drosophila

Ayukawa, Tomonori; Matsumoto, Kenjiroo; Ishikawa, Hiroyuki O.; Ishio, Akira; Yamakawa, Tomoko; Aoyama, Naoki; Suzuki, Takuya; Matsuno, Kenji
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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Notch (N) is a transmembrane receptor that mediates cell–cell interactions to determine many cell-fate decisions. N contains EGF-like repeats, many of which have an O-fucose glycan modification that regulates N-ligand binding. This modification requires GDP-l-fucose as a donor of fucose. The GDP-l-fucose biosynthetic pathways are well understood, including the de novo pathway, which depends on GDP-mannose 4,6 dehydratase (Gmd) and GDP-4-keto-6-deoxy-d-mannose 3,5-epimerase/4-reductase (Gmer). However, the potential for intercellularly supplied GDP-l-fucose and the molecular basis of such transportation have not been explored in depth. To address these points, we studied the genetic effects of mutating Gmd and Gmer on fucose modifications in Drosophila. We found that these mutants functioned cell-nonautonomously, and that GDP-l-fucose was supplied intercellularly through gap junctions composed of Innexin-2. GDP-l-fucose was not supplied through body fluids from different isolated organs, indicating that the intercellular distribution of GDP-l-fucose is restricted within a given organ. Moreover, the gap junction-mediated supply of GDP-l-fucose was sufficient to support the fucosylation of N-glycans and the O-fucosylation of the N EGF-like repeats. Our results indicate that intercellular delivery is a metabolic pathway for nucleotide sugars in live animals under certain circumstances.

Transforming Growth Factor β Signaling Upregulates the Expression of Human GDP-Fucose Transporter by Activating Transcription Factor Sp1

Xu, Yu-Xin; Ma, Anna; Liu, Li
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 12/09/2013 EN
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GDP-fucose transporter plays a crucial role in fucosylation of glycoproteins by providing activated fucose donor, GDP-fucose, for fucosyltransferases in the lumen of the Golgi apparatus. Fucose-containing glycans are involved in many biological processes, which are essential for growth and development. Mutations in the GDP-fucose transporter gene cause leukocyte adhesion deficiency syndrome II, a disease characterized by slow growth, mental retardation and immunodeficiency. However, no information is available regarding its transcriptional regulation. Here, by using human cells, we show that TGF-β1 specifically induces the GDP-fucose transporter expression, but not other transporters tested such as CMP-sialic acid transporter, suggesting a diversity of regulatory pathways for the expression of these transporters. The regulatory elements that are responsive to the TGF-β1 stimulation are present in the region between bp −330 and −268 in the GDP-fucose transporter promoter. We found that this region contains two identical octamer GC-rich motifs (GGGGCGTG) that were demonstrated to be essential for the transporter expression. We also show that the transcription factor Sp1 specifically binds to the GC-rich motifs in vitro and Sp1 coupled with phospho-Smad2 is associated with the promoter region covering the Sp1-binding motifs in vivo using chromatin immunoprecipitation (ChIP) assays. In addition...

Upregulation of Glycans Containing 3’ Fucose in a Subset of Pancreatic Cancers Uncovered Using Fusion-Tagged Lectins

Singh, Sudhir; Pal, Kuntal; Yadav, Jessica; Tang, Huiyuan; Partyka, Katie; Kletter, Doron; Hsueh, Peter; Ensink, Elliot; Birendra, KC; Hostetter, Galen; Xu, H. Eric; Bern, Marshall; Smith, David F.; Mehta, Anand S.; Brand, Randall; Melcher, Karsten; Haab,
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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The fucose post-translational modification is frequently increased in pancreatic cancer, thus forming the basis for promising biomarkers, but a subset of pancreatic cancer patients does not elevate the known fucose-containing biomarkers. We hypothesized that such patients elevate glycan motifs with fucose in linkages and contexts different from the known fucose-containing biomarkers. We used a database of glycan array data to identify the lectins CCL2 to detect glycan motifs with fucose in a 3’ linkage; CGL2 for motifs with fucose in a 2’ linkage; and RSL for fucose in all linkages. We used several practical methods to test the lectins and determine the optimal mode of detection, and we then tested whether the lectins detected glycans in pancreatic cancer patients who did not elevate the sialyl-Lewis A glycan, which is upregulated in ~75% of pancreatic adenocarcinomas. Patients who did not upregulate sialyl-Lewis A, which contains fucose in a 4’ linkage, tended to upregulate fucose in a 3’ linkage, as detected by CCL2, but they did not upregulate total fucose or fucose in a 2’ linkage. CCL2 binding was high in cancerous epithelia from pancreatic tumors, including areas negative for sialyl-Lewis A and a related motif containing 3’ fucose...

An extracellular sulfated fucose-rich polysaccharide produced by a tropical strain of cryptomonas obovata (cryptophyceae)

Giroldo, Danilo; Vieira, Armando Augusto Henriques
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
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A tropical strain of Cryptomonas obovata Skuja, isolated from a shallow oxbow lake, released a sulfated fucoserich polysaccharide. The polysaccharide is composed mainly of fucose (42%), N-acetyl-galactosamine (26%) and rhamnose (15%), with small quantities of glucuronic acid, mannose, galactose, xylose and glucose. Sulfate accounted for 1.7% total polysaccharide. Quantitative release was studied with cells exposed to optimal culture conditions contrasted with high irradiance and nitrate depletion. This latter set of conditions could simulate stress situati ons usually found in the place from which this strain was isolated. The monosaccharide composition of the polysaccharide was evaluated using PAD-HPLC and gas chromatography. The two irradiances tested (165 mol m???2 s???1 and 2000 mol m???2 s???1) had no significant effect on amounts of polysaccharide released by the cells. Differences were observed when the nitrate availability was varied. In the nitrate-depleted situation, extracellular polysaccharide production was 2.5 times higher than replete cells after 6 h at 165 mol m???2 s???1, and 2.25 times higher at 2000 mol m???2 s???1.

Biosynthesis of GDP-fucose and other sugar nucleotides in the blood-stages of Plasmodium falciparum

Sanz, Silvia; Bandini, Giulia; Ospina, Diego; Bernabeu, Maria; Mariño, Karina Valeria; Fernández Becerra, Carmen; Izquierdo, Luis
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
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Carbohydrate structures play important roles in many biological processes, including cell adhesion, cell-cell communication, and host-pathogen interactions. Sugar nucleotides are activated forms of sugars used by the cell as donors for most glycosylation reactions. Using a liquid chromatography-tandem mass spectrometry- based method, we identified and quantified the pools of UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, GDP-mannose, and GDP-fucose in Plasmodium falciparum intraerythrocytic life stages. We assembled these data with the in silico functional reconstruction of the parasite metabolic pathways obtained from the P. falciparum annotated genome, exposing new active biosynthetic routes crucial for further glycosylation reactions. Fucose is a sugar present in glycoconjugates often associated with recognition and adhesion events. Thus, the GDP-fucose precursor is essential in a wide variety of organisms. P. falciparum presents homologues of GDP-mannose 4,6-dehydratase and GDP-L-fucose synthase enzymes that are active in vitro, indicating that most GDP-fucose is formed by a de novo pathway that involves the bioconversion of GDP-mannose. Homologues for enzymes involved in a fucose salvage pathway are apparently absent in the P. falciparum genome. This is in agreement with in vivo metabolic labeling experiments showing that fucose is not significantly incorporated by the parasite. Fluorescence microscopy of epitope-tagged versions of P. falciparum GDP-mannose 4...

Study of cyclization of diphenylacetals derived from L-rhamnose and L-fucose: A theoretical approach

Bañueios-Hernández,A.E.; Mendoza-Espinoza,J.A.
Fonte: South African Journal of Chemistry Publicador: South African Journal of Chemistry
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
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This work aimed to study the configuration of two mono-tosyl-diphenylacetals, highly flexible molecules derived from L-ramnose and L-fucose, by means of the Monte Carlo conformational search method. The energy of the conformers established by this method and calculated by using the molecular mechanics force field (MMFF) permitted to establish a first conformational space. The geometry of the conformers was optimized by using the semi-empirical AM1 and the density functional B3LYP/DGDZVP methods. We were able to explain the different final products recovered from the reaction of the diphenylacetals derived from L-rhamnose and L-fucose with tosyl chloride, in a pyridine solution. On the other hand, obtaining cyclical compounds by intramolecular cyclization could be an attractive pathway for the synthesis of furanosides.