| 1. |
- de Oliveira, Felipe Marques Souza, et al.
(författare)
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Detection of post-translational modifications using solid-phase proximity ligation assay.
- 2018
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Ingår i: New biotechnology. - : Elsevier BV. - 1876-4347 .- 1871-6784. ; 45:October, s. 51-59
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Tidskriftsartikel (refereegranskat)abstract
- Post-translational modifications (PTMs) regulate protein activities to help orchestrate and fine-tune cellular processes. Dysregulation of PTMs is often related with disorders and malignancies, and may serve as a precise biomarker of disease. Developing sensitive tools to measure and monitor low-abundant PTMs in tissue lysates or serum will be instrumental for opening up new PTM-based diagnostic avenues. Here, we investigate the use of solid-phase proximity ligation assay (SP-PLA) for detection of different PTMs. The assay depends on the recognition of the target protein molecule and its modification by three affinity binders. Using antibodies and lectins, we applied the method for detection of glycosylated CD44 and E-Cadherin, and phosphorylated p53 and EGFR. The assay was found to have superior dynamic range and limit of detection compared to standard ELISAs. In summary, we have established the use of SP-PLA as an appropriate method for sensitive detection of PTMs in lysates and sera, which may provide a basis for future PTM-based diagnostic and prognostic biomarkers.
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| 2. |
- Flowers, Sarah A., et al.
(författare)
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Decrease of core 2 O-glycans on synovial lubricin in osteoarthritis reduces galectin-3 mediated crosslinking
- 2020
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 295:47, s. 16023-16036
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Tidskriftsartikel (refereegranskat)abstract
- The synovial fluid glycoprotein lubricin (also known as proteoglycan 4) is a mucin-type O-linked glycosylated biological lubricant implicated to be involved in osteoarthritis (OA) development. Lubricin's ability to reduce friction is related to its glycosylation consisting of sialylated and unsialylated Tn-antigens and core 1 and core 2 structures. The glycans on lubricin have also been suggested to be involved in crosslinking and stabilization of the lubricating superficial layer of cartilage by mediating interaction between lubricin and galectin-3. However, with the spectrum of glycans being found on lubricin, the glycan candidates involved in this interaction were unknown. Here, we confirm that the core 2 O-linked glycans mediate this lubricin-galectin-3 interaction, shown by surface plasmon resonance data indicating that recombinant lubricin (rhPRG4) devoid of core 2 structures did not bind to recombinant galectin-3. Conversely, transfection of Chinese hamster ovary cells with the core 2 GlcNAc transferase acting on a mucin-type O-glycoprotein displayed increased galectin-3 binding. Both the level of galectin-3 and the galectin-3 interactions with synovial lubricin were found to be decreased in late-stage OA patients, coinciding with an increase in unsialylated core 1 O-glycans (T-antigens) and Tn-antigens. These data suggest a defect in crosslinking of surface-active molecules in OA and provide novel insights into OA molecular pathology.
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| 3. |
- Mthembu, Yolanda H., et al.
(författare)
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Recombinant mucin-type proteins carrying LacdiNAc on differentO-glycan core chains fail to supportH. pyloribinding
- 2020
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Ingår i: Molecular Omics. - : Royal Society of Chemistry (RSC). - 1742-206X .- 1742-2051 .- 2515-4184. ; 16:3, s. 243-257
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Tidskriftsartikel (refereegranskat)abstract
- The beta 4-N-acetylgalactosaminyltransferase 3 (B4GALNT3) transfers GalNAc in a beta 1,4-linkage to GlcNAc forming the LacdiNAc (LDN) determinant on oligosaccharides. The LacdiNAc-binding adhesin (LabA) has been suggested to mediate attachment ofHelicobacter pylorito the gastric mucosaviabinding to the LDN determinant. TheO-glycan core chain specificity of B4GALNT3 is poorly defined. We investigated the specificity of B4GALNT3 on GlcNAc residues carried byO-glycan core 2, core 3 and extended core 1 precursors using transient transfection of CHO-K1 cells and a mucin-type immunoglobulin fusion protein as reporter protein. Binding of the LabA-positiveH. pyloriJ99 and 26695 strains to mucin fusion proteins carrying the LDN determinant on differentO-glycan core chains and human gastric mucins with and without LDN was assessed in a microtiter well-based binding assay, while the binding of(125)I-LDN-BSA to various clinicalH. pyloriisolates was assessed in solution. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and western blotting confirmed the requirement of a terminal GlcNAc for B4GALNT3 activity. B4GALNT3 added a beta 1,4-linked GalNAc to GlcNAc irrespective of whether the latter was carried by a core 2, core 3 or extended core 1 chain. No LDN-mediated adhesion ofH. pyloristrains 26 695 and J99 to LDN determinants on gastric mucins or a mucin-type fusion protein carrying core 2, 3 and extended core 1O-glycans were detected in a microtiter well-based adhesion assay and no binding of a(125)I-labelled LDN-BSA neoglycoconjugate to clinicalH. pyloriisolates was identified.
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| 4. |
- Venkatakrishnan, Vignesh, 1987, et al.
(författare)
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Glycan analysis of human neutrophil granules implicates a maturation-dependent glycosylation machinery
- 2020
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 295:36, s. 12648-12660
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Tidskriftsartikel (refereegranskat)abstract
- Protein glycosylation is essential to trafficking and immune functions of human neutrophils. During granulopoiesis in the bone marrow, distinct neutrophil granules are successively formed. Distinct receptors and effector proteins, many of which are glycosylated, are targeted to each type of granule according to their time of expression, a process called "targeting by timing." Therefore, these granules are time capsules reflecting different times of maturation that can be used to understand the glycosylation process during granulopoiesis. Herein, neutrophil subcellular granules were fractionated by Percoll density gradient centrifugation, andN- andO-glycans present in each compartment were analyzed by LC-MS. We found abundant paucimannosidicN-glycans and lack ofO-glycans in the early-formed azurophil granules, whereas the later-formed specific and gelatinase granules and secretory vesicles contained complexN-andO-glycans with remarkably elongatedN-acetyllactosamine repeats with Lewis epitopes. Immunoblotting and histochemical analysis confirmed the expression of Lewis X and sialyl-Lewis X in the intracellular granules and on the cell surface, respectively. Many glycans identified are unique to neutrophils, and their complexity increased progressively from azurophil granules to specific granules and then to gelatinase granules, suggesting temporal changes in the glycosylation machinery indicative of "glycosylation by timing" during granulopoiesis. In summary, this comprehensive neutrophil granule glycome map, the first of its kind, highlights novel granule-specific glycosylation features and is a crucial first step toward a better understanding of the mechanisms regulating protein glycosylation during neutrophil granulopoiesis and a more detailed understanding of neutrophil biology and function.
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| 5. |
- Flowers, Sarah A., et al.
(författare)
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Deciphering Isomers with a Multiple Reaction Monitoring Method for the Complete Detectable O-Glycan Repertoire of the Candidate Therapeutic, Lubricin
- 2019
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 91:15, s. 9819-9827
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Tidskriftsartikel (refereegranskat)abstract
- Glycosylation is a fundamental post-translational modification, occurring on half of all proteins. Despite its significance, our understanding is limited, in part due to the inherent difficulty in studying these branched, multi-isomer structures. Accessible, detailed, and quantifiable methods for studying glycans, particularly O-glycans, are needed. Here we take a multiple reaction monitoring (MRM) approach to differentiate and relatively quantify all detectable glycans, including isomers, on the heavily O-glycosylated protein lubricin. Lubricin (proteoglycan 4) is essential for lubrication of the joint and eye. Given the therapeutic potential of lubricin, it is essential to understand its O-glycan repertoire in biological and recombinantly produced samples. O-Glycans were released by reductive beta-elimination and defined, showing a range of 26 neutral, sulfated, sialylated, and both sulfated and sialylated core 1 (Gal beta 1-3GalNAc alpha 1-) and core 2 (Gal beta 1-3(GlcNAc beta 1-6)GalNAc alpha 1-) structures. Isomer-specific MRM transitions allowed effective differentiation of neutral glycan isomers as well as sulfated isomeric structures, where the sulfate was retained on the fragment ions. This strategy was not as effective with labile sialylated structures; instead, it was observed that the optimal collision energy for the m/z 290.1 sialic acid B-fragment differed consistently between sialic acid isomers, allowing differentiation between isomers when fragmentation spectra were insufficient. This approach was also effective for purchased Neu5Ac alpha 2-3Gal beta 1-4Glc and Neu5Ac alpha 2-6Gal beta 1-4Glc and for Neu5Ac alpha 2-3Gal beta 1-4GlcNAc and Neu5Ac alpha 2-6Gal beta 1-4GlcNAc linkage isomers with the Neu5Ac alpha 2-6 consistently requiring more energy for optimal generation of the m/z 290.1 fragment. Overall, this method provides an effective and easily accessible approach for the quantification and annotation of complex released O-glycan samples.
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| 6. |
- Gotz, L., et al.
(författare)
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GlycoDigest: a tool for the targeted use of exoglycosidase digestions in glycan structure determination
- 2014
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Ingår i: Bioinformatics. - : Oxford University Press (OUP). - 1367-4803 .- 1367-4811. ; 30:21, s. 3131-3133
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Tidskriftsartikel (refereegranskat)abstract
- Sequencing oligosaccharides by exoglycosidases, either sequentially or in an array format, is a powerful tool to unambiguously determine the structure of complex N- and O-link glycans. Here, we introduce GlycoDigest, a tool that simulates exoglycosidase digestion, based on controlled rules acquired from expert knowledge and experimental evidence available in GlycoBase. The tool allows the targeted design of glycosidase enzyme mixtures by allowing researchers to model the action of exoglycosidases, thereby validating and improving the efficiency and accuracy of glycan analysis.
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| 7. |
- Adamczyk, Barbara, 1985, et al.
(författare)
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Sample handling of gastric tissue and O-glycan alterations in paired gastric cancer and non-tumorigenic tissues
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Sample collection, handling and storage are the most critical steps for ensuring the highest preservation of specimens. Pre-analytical variability can influence the results as protein signatures alter rapidly after tissue excision or during long-term storage. Hence, we evaluated current state-of-the-art biobank preservation methods from a glycomics perspective and analyzed O-glycan alterations occurring in the gastric cancer tissues. Paired tumor and adjacent normal tissue samples were obtained from six patients undergoing gastric cancer surgery. Collected samples (n = 24) were either snap-frozen or heat stabilized and then homogenized. Glycans were released from extracted glycoproteins and analyzed by LC-MS/MS. In total, the relative abundance of 83 O-glycans and 17 derived structural features were used for comparison. There was no statistically significant difference found in variables between snap frozen and heat-stabilized samples, which indicated the two preservation methods were comparable. The data also showed significant changes between normal and cancerous tissue. In addition to a shift from high sialylation in the cancer area towards blood group ABO in the normal area, we also detected that the LacdiNAc epitope (N, N'-diacetyllactosamine) was significantly decreased in cancer samples. The O-glycan alterations that are presented here may provide predictive power for the detection and prognosis of gastric cancer.
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| 8. |
- 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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| 9. |
- Acharya, Shikha, 1986, et al.
(författare)
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Reduced sialyl-Lewis(x) on salivary MUC7 from patients with burning mouth syndrome
- 2019
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Ingår i: Molecular Omics. - : Royal Society of Chemistry (RSC). - 2515-4184. ; 15:5, s. 331-339
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Tidskriftsartikel (refereegranskat)abstract
- We analysed and compared MUC7 O-glycosylation and inflammatory biomarkers in saliva from female patients with burning mouth syndrome (BMS) and gender/age-matched controls. Oligosaccharides from salivary MUC7 from BMS and controls were released. Inflammatory mediators were measured by multiplex proximity extension assay. Presence of sialyl-Lewis(x) (Si-Le(x)) epitope on MUC7 was confirmed using Western blot. MUC7 O-glycans and measured inflammatory biomarkers were found to be similar between BMS and controls. However, oligosaccharides sialyl-Lewis(x) (Si-Le(x)) was found to be reduced in samples from BMS patients. Positive correlation (combined patients and controls) was found between levels of C-C motif chemokine 19 (CCL-19) and the amount of core-2 oligosaccharides on MUC7 as well as fractalkine (CX3CL1) and level of sialylation. Patients with BMS were shown to represent a heterogeneous group in terms of inflammatory biomarkers. This indicates that BMS patients could be further stratified on the basis of low-level inflammation. The results furthermore indicate that reduced sialylation of MUC7, particularly Si-Le(x), may be an important feature in patients with BMS. However, the functional aspects and potential involvement in immune regulation of Si-Le(x) remains unclear. Our data suggests a chemokine driven alteration of MUC7 glycosylation.
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| 10. |
- Aspberg, A., et al.
(författare)
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Cartilage oligomeric matrix protein forms protein complexes with synovial lubricin via non-covalent and covalent interactions
- 2017
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Ingår i: Osteoarthritis and Cartilage. - : Elsevier BV. - 1063-4584. ; 25:9, s. 1496-1504
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Understanding the cartilage surface structure, lost in arthritic disease, is essential for developing strategies to effectively restore it. Given that adherence of the lubricating protein, lubricin, to the cartilage surface is critical for boundary lubrication, an interaction with cartilage oligomeric matrix protein (COMP) was investigated. COMP, an abundant cartilage protein, is known to be important for matrix formation. Design: Synovial fluid (SF) from arthritic patients was used to detect possible COMP-lubricin complexes by immunological methods. Recombinant (RC) COMP and lubricin fragments were expressed to characterize this bonding and mass spectrometry employed to specifically identify the cysteines involved in inter-protein disulfide bonds. Results: COMP-lubricin complexes were identified in the SF of arthritic patients by Western blot, co-immunoprecipitation and sandwich ELISA. RC fragment solid-phase binding assays showed that the C-terminal (amino acids (AA) 518-757) of COMP bound non-covalently to the N-terminal of lubricin (AA 105-202). Mass spectrometry determined that although cysteines throughout COMP were involved in binding with lubricin, the cysteines in lubricin were primarily focused to an N-terminal region (AA 64-86). The close proximity of the non-covalent and disulfide binding domains on lubricin suggest a two-step mechanism to strongly bind lubricin to COMP. Conclusion: These data demonstrate that lubricin forms a complex network with COMP involving both non-covalent and covalent bonds. This complex between lubricin and the cartilage protein COMP can be identified in the SF of patients with arthritis conditions including osteoarthritis (OA) and rheumatoid arthritis (RA). (C) 2017 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
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