| 1. |
- Nilsson, Jonas, 1970, et al.
(author)
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Synthetic standard aided quantification and structural characterization of amyloid-beta glycopeptides enriched from cerebrospinal fluid of Alzheimer's disease patients
- 2019
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1
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Journal article (peer-reviewed)abstract
- An early pathological hallmark of Alzheimer's disease (AD) is amyloid-beta (A beta) deposits in the brain, which largely consist of up to 43 amino acids long A beta peptides derived from the amyloid precursor protein (APP). We previously identified a series of sialylated Tyr-10 O-glycosylated A beta peptides, 15-20 residues long, from human cerebrospinal fluid (CSF) and observed a relative increase of those in AD vs non-AD patients. We report here on the synthesis and use of an isotopically double-labeled A beta 1-15 glycopeptide, carrying the core 1Gal beta 3GalNAc alpha 1-O-Tyr-10 structure, to (1) identify by HCD LC-MS/MS the definite glycan core 1 structure of immunopurified and desialylated A beta glycopeptides in human CSF and to (2) establish a LC-MS/MS quantification method for desialylated A beta 1-15 (and A beta-17) glycopeptides and to (3) compare the concentrations of these A beta glycopeptides in CSF from 20 AD patients and 20 healthy controls. Although we unambiguously identified the core 1 structures and Tyr-10 attachment sites of the glycopeptides, we did not observe any quantitative differences, determined through both peptide and oxonium ion fragments, of the desialylated A beta 1-15 or A beta 1-17 glycopeptides between the AD and non-AD group. The new quantitative glycoproteomic approach described, using double-labeled glycopeptide standards, will undoubtedly facilitate future studies of glycopeptides as clinical biomarkers but should also embrace sialylated A beta standards to reveal specific sialylation patterns of individual A beta glycopeptides in AD patients and controls.
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| 2. |
- Nilsson, Jonas, 1970, et al.
(author)
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Targeting the glycoproteome.
- 2013
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In: Glycoconjugate journal. - : Springer Science and Business Media LLC. - 1573-4986 .- 0282-0080. ; 30:2, s. 119-36
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Journal article (peer-reviewed)abstract
- Despite numerous original publications describing the structural complexity of N- and O-linked glycans on glycoproteins, only very few answer the basic question of which particular glycans are linked to which amino acid residues along the polypeptide chain. Such structural information is of fundamental importance for understanding the biological roles of complex glycosylations as well as deciphering their non-template driven biosynthesis. This review focuses on presenting and commenting on recent strategies, specifically aimed at identifying the glycoproteome of cultured cells and biological samples, using targeted and global enrichment procedures and utilizing the high resolution power, high through-put capacity and complementary fragmentation techniques of tandem mass spectrometry. The goal is to give an update of this emerging field of protein and glyco-sciences and suggest routes to bridge the data gap between the two aspects of glycoprotein characteristics, i.e. glycan structures and their attachment sites.
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| 3. |
- Halim, Adnan, et al.
(author)
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LC-MS/MS characterization of O-glycosylation sites and glycan structures of human cerebrospinal fluid glycoproteins.
- 2013
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In: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 12:2, s. 573-584
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Journal article (peer-reviewed)abstract
- The GalNAc O-glycosylation on Ser/Thr residues of extracellular proteins has not been well characterized from a proteomics perspective. We previously reported a sialic acid capture-and-release protocol to enrich tryptic N- and O-glycopeptides from human cerebrospinal fluid glycoproteins using nanoLC-ESI-MS/MS with collision-induced dissociation (CID) for glycopeptide characterization. Here, we have introduced peptide N-glycosidase F (PNGase F) pre-treatment of CSF samples to remove the N-glycans facilitating the selective characterization of O-glycopeptides and enabling the use of an automated CID-MS2/MS3 search protocol for glycopeptide identification. We used electron capture and transfer dissociation (ECD/ETD) to pinpoint the glycosylation site(s) of the glycopeptides, identified as predominantly core 1 like HexHexNAc-O- glycans attached to 1-4 Ser/Thr residues. We characterized 108 O-glycosylations and found Pro residues preferentially in the n-1, n+1 and/or n+3 positions in relation to the Ser/Thr attachment site (n). The characterization of glycans and glycosylation sites in glycoproteins from human clinical samples provides a basis for future studies addressing the biological and diagnostic importance of specific protein glycosylations in relation to human disease.
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| 4. |
- Persson, Andrea, et al.
(author)
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Glycosaminoglycan Domain Mapping of Cellular Chondroitin/Dermatan Sulfates
- 2020
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Journal article (peer-reviewed)abstract
- Glycosaminoglycans (GAGs) are polysaccharides produced by most mammalian cells and involved in a variety of biological processes. However, due to the size and complexity of GAGs, detailed knowledge about the structure and expression of GAGs by cells, the glycosaminoglycome, is lacking. Here we report a straightforward and versatile approach for structural domain mapping of complex mixtures of GAGs, GAGDoMa. The approach is based on orthogonal enzymatic depolymerization of the GAGs to generate internal, terminating, and initiating domains, and nanoflow reversed-phase ion-pairing chromatography with negative mode higher-energy collision dissociation (HCD) tandem mass spectrometry (MS/MS) for structural characterization of the individual domains. GAGDoMa provides a detailed structural insight into the glycosaminoglycome, and offers an important tool for deciphering the complexity of GAGs in cellular physiology and pathology. © 2020, The Author(s).
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| 5. |
- Nordén, Rickard, 1977, et al.
(author)
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O-linked glycosylation of the mucin domain of the herpes simplex virus type 1 specific glycoprotein gC-1 is temporally regulated in a seed-and-spread manner.
- 2015
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In: The Journal of biological chemistry. - 1083-351X. ; 290:8, s. 5078-5091
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Journal article (peer-reviewed)abstract
- The herpes simplex virus type 1 (HSV-1) glycoprotein gC-1, participating in viral receptor interactions and immunity interference, harbors a mucin-like domain with multiple clustered O-linked glycans. Using HSV-1 infected diploid human fibroblasts, an authentic target for HSV-1 infection, and a protein immunoaffinity procedure, we enriched fully glycosylated gC-1 and a series of its biosynthetic intermediates. This fraction was subjected to trypsin digestion and a LC-MS/MS glycoproteomics approach. In parallel, we characterized the expression patterns of the 20 isoforms of human GalNAc transferases responsible for initiation of O-linked glycosylation. The gC-1 O-glycosylation was regulated in an orderly manner initiated by synchronous addition of one GalNAc unit each to T87 and T91, and one GalNAc unit to either T99 or T101, forming a core glycopeptide for subsequent additions of in all 11 GalNAc residues to selected Ser and Thr residues of the T76-L107 stretch of the mucin domain. The expression patterns of GalNAc transferases in the infected cells suggested that initial additions of GalNAc were carried out by initiating GalNAc transferases, in particular GalNAc-T2, whereas subsequent GalNAc additions were carried out by follow up transferases, in particular GalNAc-T10. Essentially all of the susceptible Ser or Thr residues had to acquire their GalNAc units before any elongation to longer O-linked glycans of the gC-1-associated GalNAc units was permitted. Since the GalNAc occupancy pattern is of relevance for receptor binding of gC-1, the data provides a model to delineate biosynthetic steps of O-linked glycosylation of the gC-1 mucin domain in HSV-1 infected target cells.
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| 6. |
- De Leoz, M. L. A., et al.
(author)
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NIST Interlaboratory Study on Glycosylation Analysis of Monoclonal Antibodies: Comparison of Results from Diverse Analytical Methods
- 2020
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In: Molecular & Cellular Proteomics. - 1535-9476. ; 19:1, s. 11-30
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Journal article (peer-reviewed)abstract
- A broad-based interlaboratory study of glycosylation profiles of a reference and modified IgG antibody involving 103 reports from 76 laboratories. Glycosylation is a topic of intense current interest in the development of biopharmaceuticals because it is related to drug safety and efficacy. This work describes results of an interlaboratory study on the glycosylation of the Primary Sample (PS) of NISTmAb, a monoclonal antibody reference material. Seventy-six laboratories from industry, university, research, government, and hospital sectors in Europe, North America, Asia, and Australia submitted a total of 103 reports on glycan distributions. The principal objective of this study was to report and compare results for the full range of analytical methods presently used in the glycosylation analysis of mAbs. Therefore, participation was unrestricted, with laboratories choosing their own measurement techniques. Protein glycosylation was determined in various ways, including at the level of intact mAb, protein fragments, glycopeptides, or released glycans, using a wide variety of methods for derivatization, separation, identification, and quantification. Consequently, the diversity of results was enormous, with the number of glycan compositions identified by each laboratory ranging from 4 to 48. In total, one hundred sixteen glycan compositions were reported, of which 57 compositions could be assigned consensus abundance values. These consensus medians provide community-derived values for NISTmAb PS. Agreement with the consensus medians did not depend on the specific method or laboratory type. The study provides a view of the current state-of-the-art for biologic glycosylation measurement and suggests a clear need for harmonization of glycosylation analysis methods.
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| 7. |
- Halim, Adnan, et al.
(author)
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Assignment of Saccharide Identities through Analysis of Oxonium Ion Fragmentation Profiles in LC-MS/MS of Glycopeptides.
- 2014
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In: Journal of proteome research. - : American Chemical Society (ACS). - 1535-3907 .- 1535-3893. ; 13:12, s. 6024-32
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Journal article (peer-reviewed)abstract
- Protein glycosylation plays critical roles in the regulation of diverse biological processes, and determination of glycan structure-function relationships is important to better understand these events. However, characterization of glycan and glycopeptide structural isomers remains challenging and often relies on biosynthetic pathways being conserved. In glycoproteomic analysis with liquid chromatography-tandem mass spectrometry (LC-MS/MS) using collision-induced dissociation (CID), saccharide oxonium ions containing N-acetylhexosamine (HexNAc) residues are prominent. Through analysis of beam-type CID spectra and ion trap CID spectra of synthetic and natively derived N- and O-glycopeptides, we found that the fragmentation patterns of oxonium ions characteristically differ between glycopeptides terminally substituted with GalNAcα1-O-, GlcNAcβ1-O-, Galβ3GalNAcα1-O-, Galβ4GlcNAcβ-O-, and Galβ3GlcNAcβ-O- structures. The difference in the oxonium ion fragmentation profiles of such glycopeptides may thus be used to distinguish among these glycan structures and could be of importance in LC-MS/MS-based glycoproteomic studies.
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| 8. |
- Mehmedbasic, Arnela, et al.
(author)
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SorLA CR-Domains Protect the Amyloid Precursor Protein against Processing.
- 2015
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In: The Journal of biological chemistry. - 1083-351X. ; 290, s. 3359-3376
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Journal article (peer-reviewed)abstract
- SorLA is a neuronal sorting receptor that is genetically associated with Alzheimer's disease. SorLA interacts directly with the amyloid precursor protein (APP) and affects the processing of the precursor, leading to a decreased generation of the amyloid-β (Aβ) peptide. The sorLA complement-type repeat (CR)-domains associate in vitro with APP, but the precise molecular determinants of sorLA-APP complex formation and the mechanisms responsible for the effect of binding on APP processing have not yet been elucidated. Here, we have generated protein expression constructs for sorLA devoid of the 11 CR-domains and for two sorLA mutants harboring substitutions of the fingerprint residues in the central CR-domains. We generated SH-SY5Y cell lines that stably express these sorLA variants to study the binding and processing of APP using co-immunoprecipitation and western blotting/ELISA assays, respectively. We found that the sorLA CR-cluster is essential for interaction with APP and that deletion of the CR-cluster abolishes the protection against APP processing. Mutation of identified fingerprint residues in the sorLA CR-domains leads to changes in the O-linked glycosylation of APP when expressed in SH-SY5Y cells. Our results provide novel information on the mechanisms behind the influence of sorLA activity on APP metabolism by controlling post-translational glycosylation in the Golgi, suggesting new strategies against amyloidogenesis in Alzheimer's disease.
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| 9. |
- Nilsson, Jonas, 1970, et al.
(author)
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Characterization of Glycan Structures of Chondroitin Sulfate-Glycopeptides Facilitated by Sodium Ion-Pairing and Positive Mode LC-MS/MS.
- 2017
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In: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1879-1123 .- 1044-0305. ; 28:2, s. 229-41
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Journal article (peer-reviewed)abstract
- Purification and liquid chromatography-tandem mass spectrometry (LC-MS/MS) characterization of glycopeptides, originating from protease digests of glycoproteins, enables site-specific analysis of protein N- and O-glycosylations. We have described a protocol to enrich, hydrolyze by chondroitinase ABC, and characterize chondroitin sulfate-containing glycopeptides (CS-glycopeptides) using positive mode LC-MS/MS. The CS-glycopeptides, originating from the Bikunin proteoglycan of human urine samples, had ΔHexAGalNAcGlcAGalGalXyl-O-Ser hexasaccharide structure and were further substituted with 0-3 sulfate and 0-1 phosphate groups. However, it was not possible to exactly pinpoint sulfate attachment residues, for protonated precursors, due to extensive fragmentation of sulfate groups using high-energy collision induced dissociation (HCD). To circumvent the well-recognized sulfate instability, we now introduced Na(+) ions to form sodiated precursors, which protected sulfate groups from decomposition and facilitated the assignment of sulfate modifications. Sulfate groups were pinpointed to both Gal residues and to the GalNAc of the hexasaccharide structure. The intensities of protonated and sodiated saccharide oxonium ions were very prominent in the HCD-MS2 spectra, which provided complementary structural analysis of sulfate substituents of CS-glycopeptides. We have demonstrated a considerable heterogeneity of the bikunin CS linkage region. The realization of these structural variants should be beneficial in studies aimed at investigating the importance of the CS linkage region with regards to the biosynthesis of CS and potential interactions to CS binding proteins. Also, the combined use of protonated and sodiated precursors for positive mode HCD fragmentation analysis will likely become useful for additional classes of sulfated glycopeptides. Graphical Abstract ᅟ.
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| 10. |
- Nilsson, Johanna, et al.
(author)
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Molecular pathogenesis of a new glycogenosis caused by a glycogenin-1 mutation.
- 2012
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In: Biochimica et biophysica acta. - : Elsevier BV. - 0006-3002. ; 1822:4, s. 493-9
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Journal article (peer-reviewed)abstract
- Glycogenin-1 initiates the glycogen synthesis in skeletal muscle by the autocatalytic formation of a short oligosaccharide at tyrosine 195. Glycogenin-1 catalyzes both the glucose-O-tyrosine linkage and the α1,4 glucosidic bonds linking the glucose molecules in the oligosaccharide. We recently described a patient with glycogen depletion in skeletal muscle as a result of a non-functional glycogenin-1. The patient carried a Thr83Met substitution in glycogenin-1. In this study we have investigated the importance of threonine 83 for the catalytic activity of glycogenin-1. Non-glucosylated glycogenin-1 constructs, with various amino acid substitutions in position 83 and 195, were expressed in a cell-free expression system and autoglucosylated in vitro. The autoglucosylation was analyzed by gel-shift on western blot, incorporation of radiolabeled UDP-(14)C-glucose and nano-liquid chromatography with tandem mass spectrometry (LC/MS/MS). We demonstrate that glycogenin-1 with the Thr83Met substitution is unable to form the glucose-O-tyrosine linkage at tyrosine 195 unless co-expressed with the catalytically active Tyr195Phe glycogenin-1. Our results explain the glycogen depletion in the patient expressing only Thr83Met glycogenin-1 and why heterozygous carriers without clinical symptoms show a small proportion of unglucosylated glycogenin-1.
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