Letteratura scientifica selezionata sul tema "Α1-3-Galactose"

ABSTRACT Galactose α1-3 galactose (Gal) trisaccharides are present on the surface of wild-type pig cells, as well as on viruses particles produced from such cells. The recognition of Gal sugars by natural anti-Gal antibodies (NAb) in human and Old World primate serum can cause the lysis of the particles via complement-dependent mechanisms and has therefore been proposed as an important antiviral mechanism. Recently, pigs have been generated that possess disrupted galactosyl-transferase (GGTA1) genes. The cells of these pigs do not express Gal sugars on their surface, i.e., are Gal null. Concerns have been raised that the risk of virus transmission from such pigs may be increased due to the absence of the Gal sugars. We investigated the sensitivity of porcine endogenous retrovirus (PERV) produced from Gal-null and Gal-positive pig cells to inactivation by purified NAb and human serum. PERV produced in Gal-null pig cells was resistant to inactivation by either NAb or human serum. In contrast, although Gal-positive PERV particles were sensitive to inactivation by NAb and human serum, they required markedly higher concentrations of NAb for inactivation compared to the Gal-positive cells from which they were produced. Complete inactivation of Gal-positive PERV particles was not achievable despite the use of high levels of NAb, indicating that NAb-mediated inactivation of cell-free PERV particles is an inefficient process.

The red alga, Betaphycus gelatinus is one of carrageenan sources in the world. The lectin from the red alga B. gelatinus was isolated by a combination of aqueous ethanol extraction, ethanol precipitation, ion-exchange chromatography and gel filtration chromatography and was designated as BGL after the specific name of alga. Lectin gave a single band with molecular mass of about 19,000 Da in both non-reducing and reducing SDS-PAGE conditions, therefore lectin exists in monomer form. The hemagglutination activities of BGL were stable over a wide range of pH from 3 to 10, temperature up 60 oC and not affected by either the presence of EDTA or addition of divalent cations, indicating that lectin requires no metal for biological activity. The hemagglutination activities of BGL were not inhibited by monosaccharides and glycoproteins, D-glucose, D-mannose, D-galactose, D-xylose, N-acetyl-galactosamine, N-acetyl-glucosamine, N-acetyl-neuraminic acid, N-acety-D-mannosamine, transferrin and fetuin, but strongly inhibited by glycoproteins bearing high-mannose type N-glycan, such as yeast mannan and porcine thyroglobulin. Lectin BGL is specific for N-glycans and may recognize terminal (α1–3) or (α1–6)-linked mannose residues in structure Man(α1-6)[Man(α1-3)]Man(α1-6)[Man(α1-3)]Man(β1-4)GlcNAc(β1-4)GlcNAc of N-glycans. High-mannose type N-glycan binding specificities of this lectin highly resemble with those of the anti-cancer, anti-virus and anti-bacteria lectins from the red algae, carrageenophytes, including Eucheuma serra (ESA-2), Eucheuma denticulatum (EDA-2), Kappaphycus striatum (KSA-2), Kappaphycus alvarezii (KAA-1 and KAA-2) and Solieria filiformis (SfL1 and SfL2). The red alga B. gelatinus could promise to be a good source of valuable lectins for application in biochemistry and biomedicine.

Bovine articular cartilage fibromodulin has been isolated from animals aged 3 months to 8 years, and the attached keratan sulphate (KS) chains digested with keratanase II. The oligosaccharides generated have been reduced, examined by high-pH anion-exchange chromatography and their structures identified by comparison with standards. It has been shown that in fibromodulin from young articular cartilage, the KS chains do not possess either non-reducing terminal (α2-6)-linked N-acetylneuraminic acid or fucose (α1-3)-linked to sulphated N-acetylglucosamine residues. However, an age-related increase has been observed in the abundance of both (α2-6)-linked N-acetylneuraminic acid and (α1-3)-linked fucose, neither of which is found in KS isolated from non-articular cartilage, irrespective of the age of the source. Interestingly, the KS chain length remains constant as a function of age, which possibly relates to a role in collagen fibril assembly. In addition, no significant age-related changes were identified in levels of galactose sulphation.

Abstract Abnormal inflammation and apoptosis are major pathogenic features of synovial fibroblasts (SF) in rheumatoid arthritis (RA). Fucosylation, an important type of glycosylation, has been identified in cancer and inflammation conditions. The role of fucosylation in RA was investigated. Real-time PCR indicated that between RASF and osteoarthritis (OA) SF (N=14 each), there was no difference in the expression of apoptosis related molecules, including tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), its receptors DR4, DR5, DR6, DcR1, DcR2, and regulators of apoptosis FLIPL and cIAPs. However, there was a higher level of α1-2-Fucosyltransferase (Fut1, P=0.016), α1-3/1-4-Fucosyltransferase (Fut3, P=0.018) and α1-3-Fucosyltransferase (Fut6, P=0.038), but not α1-6-Fucosyltransferase (Fut8, P=0.910) in RA compared to OA synovial tissues. Interestingly, a strong positive correlation between TNFα and Fut1, Fut3 and Fut6 was identified. Fut1 also correlated with Il17a. Preincubation of RASFs with 2-Deoxy-D-Galactose (15 mM/ml), a FUT1 inhibitor, decreased the sensitivity to TRA-8, an anti-human DR5 antibody, mediated apoptosis and this effect can be reversed by fucose (15 mM). Similar results were also found on human monocyte/macrophage cell lines, HL60 and THP-1. Our studies suggest that fucosylation is strongly associated with abnormal inflammation and apoptosis in RA effector cells. Fucosylation might be a novel target for RA therapy.

ABSTRACTMarine red macroalgae have emerged to be renewable biomass for the production of chemicals and biofuels, because carbohydrates that form the major component of red macroalgae can be hydrolyzed into fermentable sugars. The main carbohydrate in red algae is agarose, and it is composed ofd-galactose and 3,6-anhydro-l-galactose (AHG), which are alternately bonded by β1-4 and α1-3 linkages. In this study, a novel β-galactosidase that can act on agarooligosaccharides (AOSs) to release galactose was discovered in a marine bacterium (Vibriosp. strain EJY3); the enzyme is annotated asVibriosp. EJY3 agarolytic β-galactosidase (VejABG). Unlike thelacZ-encoded β-galactosidase fromEscherichia coli,VejABG does not hydrolyze common substrates like lactose and can act only on the galactose moiety at the nonreducing end of AOS. The optimum pH and temperature ofVejABG on an agarotriose substrate were 7 and 35°C, respectively. Its catalytic efficiency with agarotriose was also similar to that with agaropentaose or agaroheptaose. Since agarotriose lingers as the unreacted residual oligomer in the currently available saccharification system using β-agarases and acid prehydrolysis, the agarotriose-hydrolyzing capability of this novel β-galactosidase offers an enormous advantage in the saccharification of agarose or agar in red macroalgae for its use as a biomass feedstock for fermentable sugar production.

Aberrant glycosylation in tumor cells is a hallmark during carcinogenesis. KRAS gene mutations are the most well-known oncogenic abnormalities but their association with glycan alterations in pancreatic ductal adenocarcinoma (PDAC) is largely unknown. We employed patient-derived 3D organoids to culture pure live PDAC cells, excluding contamination by fibroblasts and immune cells, to gasp the comprehensive cancer cell surface glycan expression profile using lectin microarray and transcriptomic analyses. Surgical specimens from 24 PDAC patients were digested and embedded into a 3D culture system. Surface-bound glycans of 3D organoids were analyzed by high-density, 96-lectin microarrays. KRAS mutation status and expression of various glycosyltransferases were analyzed by RNA-seq. We successfully established 16 3D organoids: 14 PDAC, 1 intraductal papillary mucinous neoplasm (IPMN), and 1 normal pancreatic duct. KRAS was mutated in 13 (7 G12V, 5 G12D, 1 Q61L) and wild in 3 organoids (1 normal duct, 1 IPMN, 1 PDAC). Lectin reactivity of AAL (Aleuria aurantia) and AOL (Aspergillus oryzae) with binding activity to α1-3 fucose was higher in organoids with KRAS mutants than those with KRAS wild-type. FUT6 (α1-3fucosyltransferase 6) and FUT3 (α1-3/4 fucosyltransferase 3) expression was also higher in KRAS mutants than wild-type. Meanwhile, mannose-binding lectin (rRSL [Ralstonia solanacearum] and rBC2LA [Burkholderia cenocepacia]) signals were higher while those of galactose-binding lectins (rGal3C and rCGL2) were lower in the KRAS mutants. We demonstrated here that PDAC 3D-cultured organoids with KRAS mutations were dominantly covered in increased fucosylated glycans, pointing towards novel treatment targets and/or tumor markers.

ABSTRACT Lipoteichoic acid (LTA) is an essential bacterial membrane polysaccharide (cell wall component) that is attached to the membrane via a lipid anchor. According to the currently accepted structure of pneumococcal LTA, the polysaccharide is comprised of several repeating units, each of which starts with glucose and ends with ribitol, with the lipid anchor predicted to be Glc(β1→3)AATGal(β1→3)Glc(α1→3)-acyl2Gro, where AATGal is 2-acetamido-4-amino-2,4,6-trideoxy-d-galactose. However, this lipid anchor has not been detected in pneumococcal membranes. Furthermore, the currently accepted structure does not explain the Forssman antigen properties of LTA and predicts a molecular weight for LTA that is larger than its actual observed molecular weight. To resolve these problems, we used mass spectrometry to analyze the structure of LTA isolated from several pneumococcal strains. Our study found that the R36A pneumococcal strain produces LTA that is more representative of pneumococci than that previously characterized from the R6 strain. Analysis of LTA fragments obtained after hydrofluoric acid and nitrous treatments showed that the fragments were consistent with an LTA nonreducing terminus consisting of GalNAc(α1→3)GalNAc(β1→, which is the minimal structure for the Forssman antigen. Based on these data, we propose a revised model of LTA structure: its polysaccharide repeating unit begins with GalNAc and ends with AATGal, and its lipid anchor is Glc(α1→3)-acyl2Gro, a common lipid anchor found in pneumococcal membranes. This new model accurately predicts the observed molecular weights. The revised model should facilitate investigation of the relationship between LTA's structure and its function.

L’espèce humaine a perdu lors de l’évolution la capacité de synthétiser certains hydrates de carbone et voit sa glycosylation des protéines et des lipides modifiée par rapport aux autres mammifères. Certains motifs glycosylés acquis lors de l’ingestion de denrées d’origine animale ou produits par le microbiote intestinal peuvent être incorporés dans nos tissus et représentent de potentiels xénoantigènes stimulant la production d’anticorps. Nous sommes exposés aussi à ces xénoantigènes lors de l’administration de protéines thérapeutiques ou lors de greffe de cellules ou de tissus d’origine animale. C’est le cas par exemple des anticorps polyclonaux d’origine animale. L’α1,3-Gal et le Neu5Gc sont deux de ces xénoantigènes induisant des réponses anticorps chez l’homme et suspectées d’induire des allergies, des maladies sériques, de l’inflammation et des tumeurs. Parmi ces anticorps en cause, les sérums anti-lymphocytaires d’origine animale sont largement utilisés dans le traitement d’induction en greffe rénale et ont été testés dans diverses indications dont le diabète de type 1. Cette thèse vise à décrire les réponses anticorps dirigées contre le Neu5Gc et l’α-1,3-Gal dans le cadre de traitements par du sérum de lapin anti-thymocytes. La thèse aborde également la possible influence de ces anticorps dans l’étiologie de la sclérose en plaque. Les résultats montrent un impact quantitatif et qualitatif de l’administration de sérum de lapin anti-thymocytes sur les réponses anticorps anti-Neu5Gc, révèlent une corrélation entre le niveau de ces anticorps et la demi-vie d’une greffe rénale, mais n’ont pas permis de conclure quant à leur impact possible dans d’autres pathologies
During evolution, the human species has lost the ability to synthesize certain carbohydrates and sees its glycosylation of proteins and lipids modified compared to other mammals. Some glycosylated moieties acquired through the ingestion of food of animal origin or produced by the intestinal microbiota can be incorporated into our tissues and represent potential xeno-antigens that stimulate the production of antibodies. We are also exposed to these xeno-antigens when administering therapeutic proteins or when transplanting cells or tissues of animal origin. This is the case, for example, for polyclonal antibodies of animal origin. α1,3-Gal and Neu5Gc are two of these xeno-antigens that induce antibody responses in humans and are suspected of inducing allergies, serum diseases, inflammation and tumors. Among these antibodies, antilymphocytic sera of animal origin are widely used in induction treatment in kidney transplantation and have been tested in various indications including type 1 diabetes. This thesis aims to describe antibody responses against Neu5Gc and α-1,3-Gal in the context of rabbit serum antithymocyte treatments. The thesis also discusses the possible influence of these antibodies in the etiology of multiple sclerosis. The results show a quantitative and qualitative impact of rabbit antithymocyte serum administration on anti-Neu5Gc antibody responses, reveal a correlation between the level of these antibodies and the half-life of a kidney transplant, but did not allow to conclude as to their possible impact in other pathologies