Monosaccharides L-fucose Research Articles

The Effects of Brown Algae-Derived Monosaccharide L-Fucose on Lipid Metabolism in C57BL/6J Obese Mice.

Obesity is a global public health problem and a risk factor for several metabolic disorders as well as cancer. In this study, we investigated the effects of L-fucose on lipid metabolism through chronic and acute in vivo experiments in mice. In the chronic test, mice were fed a high-calorie diet (HCD) containing 0.0001%, 0.001%, 0.01%, and 0.1% L-fucose for one month. The L-fucose supplementation inhibited body weight and visceral fat mass gain in HCD-fed mice. The results of the acute test showed that L-fucose increased the ratio of serum high molecular weight adiponectin and enhanced glucose and lipid catabolism. Furthermore, L-fucose also decreased the expression of adipogenic genes (peroxisome proliferator-activated receptor γ and cluster of differentiation 36). In conclusion, this study provides a new approach to combat obesity and the related diseases.

C1q/TNF-Related Protein 6 Is a Pattern Recognition Molecule That Recruits Collectin-11 from the Complement System to Ligands.

C1q/TNF-related protein (CTRP) 6 is a member of the CTRP protein family associated with the regulation of cellular and endocrine processes. CTRP6 contains collagen and globular structures, resembling the pattern recognition molecules (PRMs) of the classical and lectin complement pathways. We expressed human CTRP6 in Chinese hamster ovary cells and investigated the binding to different putative ligands (acetylated BSA [AcBSA], zymosan, mannan, and LPS from Escherichia coli and Salmonella as well as to the monosaccharides l-fucose, d-mannose, N-acetylglucosamine, N-acetylgalactosamine, and galactose). Furthermore, we investigated the binding of CTRP6 to various Gram-negative bacteria as well as PRMs and enzymes of the lectin complement pathway. We found that CTRP6 bound to AcBSA and to a lesser extent to zymosan. Using EDTA as chelating agent, we observed an increased binding to AcBSA, zymosan and the two strains of LPS. We detected no binding to mannan and BSA. We identified l-fucose as a ligand for CTRP6 and that it bound to certain enteroaggregative Escherichia coli and Pseudomonas aeruginosa isolates, whereas to other bacterial isolates, no binding was observed. CTRP6 did not appear to interact directly with the activating enzymes of the lectin pathway; however, we could show the specific recruitment of collectin-11 and subsequent initiation of the complement cascade through deposition of C4. In conclusion, our results demonstrate the binding of CTRP6 to a variety of microbial and endogenous ligands identifying CTRP6 as a novel human lectin and PRM of importance for complement recognition and innate immunity.

Plant Fucosyltransferases and the Emerging Biological Importance of Fucosylated Plant Structures

Plants frequently incorporate the monosaccharide l-fucose (Fuc; 6-deoxy-l-galactose) into glycans and glycopolymers located in diverse cellular locations. The incorporation of Fuc onto these varied glycans is carried out by fucosyltransferases (FUTs), that make up a protein superfamily with equally varied and diverse functions. The structures wherein Fuc is found have numerous proposed and validated functions, ranging from plant growth and development, cell expansion, adhesion, and signaling, to energy metabolism, among others. FUTs from several different plant species have been identified and described; however, very few of them have been extensively characterized biochemically and biologically. In this review, we summarize plant FUTs that have been biochemically characterized and biologically investigated for associated phenotypes, offering greater insight and understanding into the physiological importance of Fuc in plants and in plant cell wall structures, glycans, and proteins.

Nature-inspired engineering of an F-type lectin for increased binding strength.

Individual lectin-carbohydrate interactions are usually of low affinity. However, high avidity is frequently attained by the multivalent presentation of glycans on biological surfaces coupled with the occurrence of high order lectin oligomers or tandem repeats of lectin domains in the polypeptide. F-type lectins are l-fucose binding lectins with a typical sequence motif, HX(26)RXDX(4)R/K, whose residues participate in l-fucose binding. We previously reported the presence of a few eukaryotic F-type lectin domains with partial sequence duplication that results in the presence of two l-fucose-binding sequence motifs. We hypothesized that such partial sequence duplication would result in greater avidity of lectin-ligand interactions. Inspired by this example from Nature, we attempted to engineer a bacterial F-type lectin domain from Streptosporangium roseum to attain avid binding by mimicking partial duplication. The engineered lectin demonstrated 12-fold greater binding strength than the wild-type lectin to multivalent fucosylated glycoconjugates. However, the affinity to the monosaccharide l-fucose in solution was similar and partial sequence duplication did not result in an additional functional l-fucose binding site. We also cloned, expressed and purified a Branchiostoma floridae F-type lectin domain with naturally occurring partial sequence duplication and confirmed that the duplicated region with the F-type lectin sequence motif did not participate in l-fucose binding. We found that the greater binding strength of the engineered lectin from S. roseum was instead due to increased oligomerization. We believe that this Nature-inspired strategy might be useful for engineering lectins to improve binding strength in various applications.

2-Fluoro-L-Fucose Is a Metabolically Incorporated Inhibitor of Plant Cell Wall Polysaccharide Fucosylation.

The monosaccharide L-fucose (L-Fuc) is a common component of plant cell wall polysaccharides and other plant glycans, including the hemicellulose xyloglucan, pectic rhamnogalacturonan-I (RG-I) and rhamnogalacturonan-II (RG-II), arabinogalactan proteins, and N-linked glycans. Mutations compromising the biosynthesis of many plant cell wall polysaccharides are lethal, and as a result, small molecule inhibitors of plant cell wall polysaccharide biosynthesis have been developed because these molecules can be applied at defined concentrations and developmental stages. In this study, we characterize novel small molecule inhibitors of plant fucosylation. 2-fluoro-L-fucose (2F-Fuc) analogs caused severe growth phenotypes when applied to Arabidopsis seedlings, including reduced root growth and altered root morphology. These phenotypic defects were dependent upon the L-Fuc salvage pathway enzyme L-Fucose Kinase/ GDP-L-Fucose Pyrophosphorylase (FKGP), suggesting that 2F-Fuc is metabolically converted to the sugar nucleotide GDP-2F-Fuc, which serves as the active inhibitory molecule. The L-Fuc content of cell wall matrix polysaccharides was reduced in plants treated with 2F-Fuc, suggesting that this molecule inhibits the incorporation of L-Fuc into these polysaccharides. Additionally, phenotypic defects induced by 2F-Fuc treatment could be partially relieved by the exogenous application of boric acid, suggesting that 2F-Fuc inhibits RG-II biosynthesis. Overall, the results presented here suggest that 2F-Fuc is a metabolically incorporated inhibitor of plant cellular fucosylation events, and potentially suggest that other 2-fluorinated monosaccharides could serve as useful chemical probes for the inhibition of cell wall polysaccharide biosynthesis.

Synthesis of mannoheptose derivatives and their evaluation as inhibitors of the lectin LecB from the opportunistic pathogen Pseudomonas aeruginosa

Biofilm formation and chronic infections with Pseudomonas aeruginosa depend on lectins produced by the bacterium. The bacterial C-type lectin LecB binds to the two monosaccharides l-fucose and d-mannose and conjugates thereof. Previously, d-mannose derivatives with amide and sulfonamide substituents at C6 were reported as potent inhibitors of the bacterial lectin LecB and LecB-mediated bacterial surface adhesion. Because d-mannose establishes a hydrogen bond via its 6-OH group with Ser23 of LecB in the crystal structure and may be beneficial for binding affinity, we extended d-mannose and synthesized mannoheptoses bearing the free 6-OH group as well as amido and sulfonamido-substituents at C7. Two series of diastereomeric mannoheptoses were synthesized and the stereochemistry was determined by X-ray crystallography. The potency of the mannoheptoses as LecB inhibitors was assessed in a competitive binding assay. The data reveal a diastereoselectivity of LecB for (6S)-mannoheptose derivatives with increased activity over methyl α-d-mannoside.

Safety evaluation of the human-identical milk monosaccharide, l-fucose

l-Fucose is a natural monosaccharide present in mammals where it is found predominantly as an O-glycosidically linked component of glycoproteins, glycolipids, and oligosaccharides. It is also present in its free form in human breast milk (human milk monosaccharide). l-Fucose plays important roles in the development of the immune and nervous systems and is involved in cognitive function and memory formation. The human-identical milk monosaccharide l-fucose is therefore proposed for use in infant formulas to better simulate the free saccharides present in human breast milk. As part of the safety evaluation of l-fucose, a subchronic dietary toxicity study preceded by an in utero phase was conducted in Sprague–Dawley rats. l-Fucose was without maternal toxicity or compound-related adverse effects on female reproduction and general growth and development of offspring at a maternal dietary level up to 1%, equivalent to a dose of 1655mg/kgbodyweight(bw)/day. During the subchronic phase, no compound-related adverse effects were observed in first generation rats at dietary levels of up to 1% (highest level tested), corresponding to doses of 516 and 665mg/kgbw/day in males and females, respectively. l-Fucose was non-genotoxic in a series of in vitro genotoxicity/mutagenicity tests. These results support the safe use of l-fucose in infant formula and as a food ingredient at levels equivalent to those present in human breast milk.

Fucoidan stimulates cell division in the amebocyte-producing organ of the schistosome-transmitting snail Biomphalaria glabrata

Adult Salvador (schistosome-resistant) strain Biomphalaria glabrata snails were injected with 5μl of 10mg/ml solutions of the sulfated polysaccharides λ carageenan, dextran sulfate, fucoidan, and heparin, the nonsulfated polysaccharide laminarin, and the monosaccharides L-fucose and L-galactose, and mitotic activity in the amebocyte-producing organ (APO) was measured in histological sections at 24h post injection. Among the substances tested, only fucoidan induced elevated mitotic activity. Desulfated fucoidan was not mitogenic, indicating that sulfate groups are required for activity. Schistosome-susceptible M-line snails possessed minimal or no hematopoietic tissue in their APO, which did not respond to fucoidan. Immersion of juvenile Salvador snails in 1 or 10mg/ml solutions of fucoidan for 3h did not elevate mitotic activity at 24h post immersion, suggesting that the external and digestive tract epithelia of B. glabrata are impermeable to this molecule. These results provide support for the hypothesis that fucosylated glycans on the tegument and in excretory–secretory products of sporocysts of Schistosoma mansoni are in part responsible for increased mitotic activity in the APO of B. glabrata infected with this trematode or injected with its extracts.

Effect of Monosaccharide L-fucose and Polysaccharide Fucoidan on Sperm ??L-fucosidase Activity and Relation to Sperm-oocyte Interaction in Pig

Carbohydrate-protein interactions are known to be important in gamete interactions. Several evidence indicated that a fucose-containing sulfated polysaccharide fucoidan was potential inhibitor of fertilization in vitro and thus fucose seemed to be part of the recognition signal of gamete interaction in mammals. In recent investigation we found that α-L-fucosidase activity was present in boar spermatozoa and it was related to sperm binding to and penetration into zona pellucida (ZP) in vitro. The objective of this study was to determine the effects of monosaccharide L-fucose and polysaccharide fucoidan on sperm α-L-fucosidase activity and relation to sperm-oocyte interaction in pig. Results indicated that the activity of sperm α-L-fucosidase was largely inhibited (62%) when sperm suspension was treated with monosaccharide L-fucose. It also significantly inhibited the number of sperm binding to ZP (32%) and penetration into zona-intact oocytes (72%), but did not inhibit penetration into zona-free oocytes when fertilization medium contained L-fucose. The chlorotetracycline (CTC) assessment showed that L-fucose did not affect induction of sperm capacitation and acrosome reaction. In contrast, the activity of sperm α-L-fucosidase was not inhibited when sperm suspension was treated with polysaccharide fucoidan but sperm-ZP binding was greatly inhibited (85%) and completely blocked sperm penetration into zona-intact or zona-free oocytes. The CTC assessment showed that fucoidan increased the F pattern and decreased the AR pattern sperm. These results suggested that the different inhibitory mechanisms were present between monosaccharide L-fucose and polysaccharide fucoidan on sperm-oocyte interaction, the inhibition effect of α-L-fucose on sperm binding and penetrating into ZP caused sperm α-L-fucosidase inhibited by α-L-fucose.

An in vitro assessment of mucus/mucoadhesive interactions

One proposed mechanism of mucoadhesion involves the interpenetration of the mucus/mucoadhesive molecules, followed by the formation of secondary chemical bonds. In this study the nature of interactions between the mucus gel and the mucoadhesive macromolecule was investigated. A logarithmic frequency sweep between 10 and 0.002 Hz was used to investigate the nature of interactions between homogenised mucus gel and the model mucoadhesive Carbopol 934P (C934) at pH 6.2. The rheogram obtained was found to be intermediate between a physically entangled system and a cross-linked system, and was found to closely resemble that of a mixture of mucus glycoprotein (major structure forming component of the mucus gel) and C934 at pH 6.2. Furthermore, it was found that the addition of the hydrogen bond breaking agents urea and potassium thiocyanate (KCNS) to a mixture of homogenised mucus/C934 at pH 6.2 resulted in a reduction in the G′ (storage modulus) as well as the G′(loss modulus) of the mixture. The addition of the model monosaccharides l-fucose and d-galacturonic acid to the mucoadhesive poly(acrylic acid) (paa) shifted the paa carboxylic acid signals upfield and downfield, respectively, when tested using 13C-NMR. The addition of urea and KCNS to the l-fucose/paa as well as the paa/water control mixtures at pH 6.2 resulted in a positional change in the chemical shift of the paa carboxylic acid signals, when examined using 13C-NMR. Finally, the incorporation of urea into 50 mg C934 or poly(ethylene oxide) discs resulted in a reduction in their mucoadhesive strength in vitro. It is concluded that the mucoadhesive polymer could interact with the mucus glycoproteins by forming physical entanglements followed by hydrogen bonds with sugar residues on the oligosaccharide chains, resulting in the formation of a strengthened mucus gel network, which allows the mucoadhesive system to remain adhesive for an extended period of time. Disruption of hydrogen bonds could substantially reduce the adhesive strength of a mucoadhesive system, suggesting the importance of these bonds in mucoadhesion.

Macrophage migration inhibition induced by MDP, LPS, PMA, and MIF/MAF: reversal by macrophage migration enhancement factor (MEF), L-fucose, L-fucosyl BSA, D-mannose, and D-mannosyl BSA.

Our data establish that migration inhibition factor (MIF) and migration enhancement factor (MEF) mutually neutralize the effect of each other in a concentration-dependent manner. The monosaccharides L-fucose and D-mannose were also shown to reverse MIF and additionally to stimulate alveolar macrophage (AM) migration in the absence of MIF. The specific activity of these sugars was increased 200-fold when conjugated to bovine serum albumin (BSA). Macrophage activation is usually observed concurrently with migration inhibition when macrophages are incubated with MIF preparations. Migration inhibition occurred also when AM were incubated in the presence of known metabolic activators (MDP, PMA, and LPS). It was found that L-fucose, D-mannose, L-fucosyl BSA, and D-mannosyl BSA could reverse migration inhibition caused by MIF as well as by these metabolic activators. These observations suggest that reversal of MIF by L-fucose is unexplained solely on the basis that L-fucose is functioning as a competitive inhibitor; instead, they suggest that MEF and the above sugars and their conjugates stimulate AM through a receptor system different from the MIF receptor. These observations support the concept that MEF is an important macrophage modulator in CMI responses.

Mononuclear cell factors that inhibit fibroblast collagen synthesis. II. Properties of the factors.

Supernatants harvested from peripheral blood mononuclear cells (PBMC) incubated either with the non-specific mitogen phytohaemagglutinin-P (PHA) or with the specific antigen tuberculin purified protein derivative for 72 h decreased collagen synthesis by dermal fibroblasts. PHA-induced mononuclear cell factors (PHA-MCF) responsible for decreases in collagen synthesis by dermal fibroblasts were localized by column chromatography on Sephacryl S-200 to fractions of 30,000-60,000 daltons. Proteolytic enzymes destroyed the activity of PHA-MCF, but after incubation with neuraminidase some activity of these factors remained. The activity of PHA-MCF was not inhibited by incubation with the monosaccharides L-fucose, L-rhamnose, N-acetylglucosamine, and alpha-methyl-D-mannoside but was partially destroyed by heating at 80 degrees C for 10 min. The factors were not mitogenic to PBMC. These factors did not appear to resemble any previously characterized factors produced by non-adherent mononuclear cells. The mechanism by which these factors decreased fibroblast collagen synthesis appeared complex. There was no detectable increase in the release of collagenase by fibroblasts, nor was a cytotoxic effect apparent. Increased PGE2 production by fibroblasts could not be related to the factor-induced decrease in fibroblast collagen synthesis.