| 1. |
- Axelsson, Magnus A. B., et al.
(författare)
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Neutralization of pH in the Golgi apparatus causes redistribution of glycosyltransferases and changes in the O-glycosylation of mucins.
- 2001
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 11:8, s. 633-44
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Tidskriftsartikel (refereegranskat)abstract
- Addition of the weak base ammonium chloride (NH4Cl) or the proton pump inhibitor bafilomycin A1 to cultured HeLa and LS 174T cells effectively neutralized the pH gradient of the secretory pathway. This resulted in relocalization of the three studied glycosyltransferases, N-acetylgalactosaminyltransferase 2, beta1,2 N-acetylglucosaminyltransferase I, and beta1,4 galactosyltransferase 1, normally localized to the Golgi stack, the medial/trans-Golgi and the trans-Golgi/TGN, respectively. Indirect immunofluorescence microscopy, immunoelectron microscopy, and subcellular fractionation of the tagged or native glycosyltransferases showed that NH4Cl caused a relocalization of the enzymes mainly to vesicles of endosomal type, whereas bafilomycin A1 gave mainly cell surface staining. The general morphology of the endoplasmic reticulum and Golgi apparatus was retained as judged from immunofluorescence and electron microscopy studies. When the O-glycans on the guanidinium chloride insoluble gel-forming mucins from the LS 174T cells were analyzed by gas chromatography-mass spectrometry after neutralization of the secretory pathway pH by NH4Cl over 10 days shorter O-glycans were observed. However, no decrease in the number of oligosaccharide chains was indicated. Together, the results suggest that pH is a contributing factor for proper steady-state distribution of glycosyltransferases over the Golgi apparatus and that altered pH may cause alterations in glycosylation possibly due to a relocalization of glycosyltransferases.
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| 2. |
- Cherian, Reeja Maria, et al.
(författare)
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Shiga-like toxin binds with high avidity to multivalent O-linked blood group P1 determinants on mucin-type fusion proteins
- 2014
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 24:1, s. 26-38
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Tidskriftsartikel (refereegranskat)abstract
- The binding of Shiga-like toxin 1 (Stx1) and Shiga-like toxin 2 (Stx2) to a mucin-like fusion protein, P-selectin glycoprotein ligand-1/mouse IgG(2b) (PSGL-1/mIgG(2b)), carrying multiple copies of the blood group P1 determinant on O-glycans was investigated with western blot and the biosensor Biacore. Chinese hamster ovary K-1 (CHO-K1) cells were stably transfected with linearized plasmids encoding the PSGL-1/mIgG(2b) fusion protein, the pigeon alpha 1,4-galactosyltransferase (alpha 4Gal-T) and the core 2 beta 1,6-N-acetylglucosaminyltransferase (C2GnT-I). Western blot analyses of purified PSGL-1/mIgG(2b) and liquid chromatography-mass spectrometry (LC-MS) of released O-glycans confirmed the presence of the P1 determinant. Western blot analysis indicated strong binding of Stx1, but not Stx2, to PSGL-1/mIgG(2b). In a Biacore assay, Stx1 and Stx2 were immobilized on a dextran chip and the binding of purified PSGL-1/mIgG(2b) and a P-k-albumin neoglycoprotein was analyzed. Stx1 and Stx2 bound with high avidity to both PSGL-1/mIgG(2b) and P-k-albumin, while the Stx1 binding was the strongest. In summary, we have shown that the pigeon alpha 4Gal-T can be aberrantly expressed in CHO cells together with the core 2 enzyme to generate multiple, O-linked P1 determinants on a simultaneously expressed mucin-type fusion protein. P1-decorated PSGL-1/mIgG(2b) bound with high avidity to both Stx1 and Stx2, and as such constitutes a potential therapeutic inhibitor of these toxins.
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| 3. |
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| 4. |
- Karlsson, Niclas G., 1966, et al.
(författare)
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O-Linked glycome and proteome of high-molecular-mass proteins in human ovarian cancer ascites: Identification of sulfation, disialic acid and O-linked fucose
- 2012
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 22:7, s. 918-929
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Tidskriftsartikel (refereegranskat)abstract
- The O-linked glycosylation of the main acidic high-molecular-weight glycoprotein from ascites fluid from patients with ovarian cancer were analyzed. The O-linked oligosaccharides were shown to consist of mainly highly sialylated core 1 and 2 structures with a smaller amount of sulfated core 2 structures. These structures were shown to be able to be further extended into small keratan sulfate (KS)-type oligosaccharides with up to four N-acetyllactosamine units. Proteomic studies of the acidic fraction of ascites fluid from patients with ovarian cancer showed that this fraction was enriched in proteoglycans. Among them, lumican, agrin, versican and dystroglycans were potential candidates, with threonine- and serine-rich domains that could carry a significant amount of O-linked glycosylation, including also the O-linked KS. Glycomic analysis using liquid chromatography (LC)-tandem mass spectrometry (MS/MS) also showed that the disialic acid NeuAc-NeuAc- was frequently found as the terminating structure on the O-linked core 1 and 2 oligosaccharides from one ascites sample. Also, a small amount of the epidermal growth factor (EGF)-associated O-linked fucose structure Gal-GlcNAc-Fucitol was detected with and without sialic acid in the LC-MS/MS analysis. Candidate proteins containing O-linked fucose were suggested to be proteoglycan-type molecules containing the O-linked fucose EGF consensus domain.
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| 5. |
- Karlsson, Niclas G., 1966, et al.
(författare)
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Salivary MUC7 is a major carrier of blood group I type O-linked oligosaccharides serving as the scaffold for sialyl Lewis x.
- 2009
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 19:3, s. 288-300
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Tidskriftsartikel (refereegranskat)abstract
- Isolation of salivary MUC7 with gel electrophoresis allowed analysis by LC-MS and LC-MS(2) of released O-linked oligosaccharides and a thorough description of the glycosylation of this molecule, where high-molecular-weight oligosaccharides up to the size of 2790 Da and with up to three sialic acid residues were identified. A common theme of these novel high abundant oligosaccharides on MUC7 showed that the C-3 branch of the oligosaccharides consisted of branched I-antigen type structural epitopes (GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-), where the branch point was initiated on core 1 and core 2 galactose residues, and the branches were terminated by sialyl type 2 and sialyl Lewis x epitopes. Six sulfated sialylated oligosaccharides of low intensity were also identified, with the sulfate mainly on N-acetyl glucosamine residues located close to the reducing termini. One of these oligosaccharides was identified as a candidate for the high-affinity L-selectin ligand 6'-sulfo sialyl Lewis x. Neutral oligosaccharides and blood group antigens were found to be less abundant on MUC7 and the glycosylation appeared to be more preserved between individuals as compared to salivary MUC5B. This was illustrated by comparing the LC-MS spectra of MUC7 and MUC5B glycans from secretors (23 individuals) and nonsecretors (6 individuals). The data show that MUC7 provides a multivalent scaffold for sialylation, meeting the requirement for high-avidity binding via its glycosylation and mediator of the interaction between immune cells such as salivary neutrophils and oral bacteria.
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| 6. |
- Kenny, Diarmuid T., et al.
(författare)
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Presence of terminal N-acetylgalactosamineβ1-4N-acetylglucosamine residues on O-linked oligosaccharides from gastric MUC5AC: involvement in Helicobacter pylori colonization?
- 2012
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 22:8, s. 1077-85
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Tidskriftsartikel (refereegranskat)abstract
- Isolation of MUC5AC mucins from the gastric mucosa from two secretor individuals (one from normal mucosa from a patient with gastric cancer and one from a control) showed different abilities to bind and induce the proliferation of the Helicobacter pylori strain J99. Analysis of the released O-linked oligosaccharides by LC-MS from these individuals showed a very heterogeneous mixture of species from the cancer patient containing both neutral and sialylated structures, whereas the normal sample showed dominating neutral blood group H terminating structures as well as neutral structures containing the di-N-acetyllactosamine (lacdiNAc) unit GalNAcβ1-4GlcNAcβ1- on the C-6 branch of the reducing end GalNAc. The linkage configuration of these epitopes were determined using C-4-specific fragmentation for the GalNAcβ1-4GlcNAcβ1- glycosidic linkage, comparison of the MS(3) fragmentation with standards for linkage configuration and N-acetylhexosamine type as well as exoglycosidase treatment. It was also shown that the lacdiNAc epitope is present in both human and porcine gastric mucins, indicating that this is an epitope preserved between species. We hypothesize that the termination on gastric MUC5AC with lacdiNAc is in competition with complex glycosylation such as the Le(b) and H type 1 as well as complex sialylated structures. These are epitopes known to bind the H. pylori BabA and SabA adhesins.
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| 7. |
- Lindberg, L., et al.
(författare)
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Mucin-type fusion proteins with blood group A or B determinants on defined O-glycan core chains produced in glycoengineered Chinese hamster ovary cells and their use as immunoaffinity matrices
- 2013
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 23:6, s. 720-735
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Tidskriftsartikel (refereegranskat)abstract
- Assays for quantification, and methods for removal, of anti-A and anti-B antibodies are the key for the success of ABO incompatible organ transplantation programs. In order to produce tools that can be used as substrates in tests for anti-A/anti-B quantification and specificity determination or as affinity matrices in extracorporeal immunoadsorption (IA) columns, we engineered Chinese hamster ovary (CHO) cells secreting mucin-type fusion proteins carrying blood group A or B determinants on defined O-glycan core saccharide chains. Besides the P-selectin glycoprotein ligand-1/mouse immunoglobulin G2b (PSGL-1/mIgG2b) cDNA, CHO cells were transfected with plasmids encoding core 2 (β1,6GlcNAc-T1) or core 3 (β1,3GlcNAc-T6 and β1,3Gal-T5) enzymes together with α1,2Fuc-T1 or α1,2Fuc-T2 and the A or B gene-encoded α1,3GalNAcT or α1,3Gal-T, respectively. Selected clones with the correct glycophenotype were expanded and cultured in shaker flasks and Wave bioreactors. Western blotting was used to characterize purified fusion protein and liquid chromatography–mass spectrometry was used to characterize the released O-glycans. Clones producing PSGL-1/mIgG2b carrying O-glycans with A and B determinants on type 1 (Galβ3GlcNAc), type 2 (Galβ4GlcNAc) and type 3 (Galβ3GalNAcα) outer core saccharide chains were established. The conversion of CHO cells from exclusive inner core 1 (Galβ3GalNAc) to core 3 (GlcNAcβ3GalNAc) O-glycan producers was almost complete, whereas conversion to inner core 2 (GlcNAcβ6GalNAc) O-glycans was incomplete as was the α2-fucosylation of the core 1 chain. Sialylation may prevent these biosynthetic steps. The clinical utility of the blood group A and B substituted mucin-type fusion proteins as substrates in enzyme-linked immunosorbent assay or as affinity matrices in IA columns is explored.
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| 8. |
- Liu, Y., et al.
(författare)
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The minimum information required for a glycomics experiment (MIRAGE) project: improving the standards for reporting glycan microarray-based data
- 2017
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 27:4, s. 280-284
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Tidskriftsartikel (refereegranskat)abstract
- MIRAGE (Minimum Information Required for A Glycomics Experiment) is an initiative that was created by experts in the fields of glycobiology, glycoanalytics and glycoinformatics to produce guidelines for reporting results from the diverse types of experiments and analyses used in structural and functional studies of glycans in the scientific literature. As a sequel to the guidelines for sample preparation (Struwe et al. 2016, Glycobiology, 26: 907-910) and mass spectrometry data (Kolarich et al. 2013, Mol. Cell Proteomics, 12: 991-995), here we present the first version of guidelines intended to improve the standards for reporting data from glycan microarray analyses. For each of eight areas in the workflow of a glycan microarray experiment, we provide guidelines for the minimal information that should be provided in reporting results. We hope that the MIRAGE glycan microarray guidelines proposed here will gain broad acceptance by the community, and will facilitate interpretation and reproducibility of the glycan microarray results with implications in comparison of data from different laboratories and eventual deposition of glycan microarray data in international databases.
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| 9. |
- Struwe, Weston B, et al.
(författare)
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The minimum information required for a glycomics experiment (MIRAGE) project: sample preparation guidelines for reliable reporting of glycomics datasets.
- 2016
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 26:9, s. 907-910
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Tidskriftsartikel (refereegranskat)abstract
- The minimum information required for a glycomics experiment (MIRAGE) project was established in 2011 to provide guidelines to aid in data reporting from all types of experiments in glycomics research including mass spectrometry (MS), liquid chromatography, glycan arrays, data handling and sample preparation. MIRAGE is a concerted effort of the wider glycomics community that considers the adaptation of reporting guidelines as an important step towards critical evaluation and dissemination of datasets as well as broadening of experimental techniques worldwide. The MIRAGE Commission published reporting guidelines for MS data and here we outline guidelines for sample preparation. The sample preparation guidelines include all aspects of sample generation, purification and modification from biological and/or synthetic carbohydrate material. The application of MIRAGE sample preparation guidelines will lead to improved recording of experimental protocols and reporting of understandable and reproducible glycomics datasets.
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| 10. |
- Thomsson, Kristina A, 1969, et al.
(författare)
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MUC5B glycosylation in human saliva reflects blood group and secretor status.
- 2005
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 15:8, s. 791-804
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to characterize human salivary glycoforms and the natural glycosylation variation of the major ABO blood group bearing high molecular weight glycoprotein fraction MG1, which mainly consists of MUC5B mucin. Reduced and alkylated mucins from individuals of blood group A, B, and O were purified by sodium dodecyl sulfate-agarose/polyacrylamide composite gel electrophoresis (SDS-AgPAGE), blotted to polyvinylidene fluoride (PVDF) membranes, and visualized with alcian blue. O-linked oligosaccharides were released from MUC5B glycoform bands by reductive beta-elimination and analyzed by liquid chromatography (LC) electrospray ion trap mass spectrometry (MS). Slow electrophoretically migrating MUC5B components (sm) were found to be dominated by neutral oligosaccharides, and fast-migrating (fm) components were dominated by sulfated oligosaccharides. ABO blood group-specific sequences were found on all glycoforms, and novel oligosaccharides containing blood group A and B type sequences were sequenced. This is the first molecular description of the influence of the blood group ABO system on salivary MUC5B oligosaccharides. Expanding these results from the three A, B, and O individuals into larger population (29 individuals), we found oligosaccharide sequences corresponding to the blood group of the donor on MUC5B from 23 individuals. The remaining six individuals were characterized by a high degree of sialylation. These individuals were assigned as nonsecretors, whereas blood group-expressing individuals were assigned as secretors. Western blot assays with antibodies confirmed increased expression of Sialyl Lewis a (Si-Le(a)) in the nonsecretors. Our results highlight that salivary MUC5B consists of glycoforms with distinct glycosylation that vary extensively between individuals and that some of this variation is owing to blood group and secretor status.
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