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Glycosylation of a CNS-specific extracellular matrix glycoprotein, tenascin-R, is dominated by O-linked sialylated glycans and "brain-type” neutral N-glycans

Zamze, Susanne ; Harvey, David J. ; Pesheva, Penka ; Mattu, Taj S. ; Schachner, Melitta ; Dwek, Raymond A. ; Wing, David R.

In: Glycobiology, 1999, vol. 9, no. 8, p. 823-831

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    Title
    • Glycosylation of a CNS-specific extracellular matrix glycoprotein, tenascin-R, is dominated by O-linked sialylated glycans and "brain-type” neutral N-glycans
    Author
    • Zamze, Susanne. Glycobiology Institute, Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK, CH-8093 Zürich, Switzerland
    • Harvey, David J.. Glycobiology Institute, Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK, CH-8093 Zürich, Switzerland
    • Pesheva, Penka. Department of Neurobiology, ETH-Honggerberg, CH-8093 Zürich, Switzerland
    • Mattu, Taj S.. Glycobiology Institute, Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK, CH-8093 Zürich, Switzerland
    • Schachner, Melitta. Department of Neurobiology, ETH-Honggerberg, CH-8093 Zürich, Switzerland
    • Dwek, Raymond A.. Glycobiology Institute, Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK, CH-8093 Zürich, Switzerland
    • Wing, David R.. Glycobiology Institute, Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK, CH-8093 Zürich, Switzerland
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:304438
    Summary
    As a member of the tenascin family of extracellular matrix glycoproteins, tenascin-R is located exclusively in the CNS. It is believed to play a role in myelination and axonal stabilization and, through repulsive properties, may contribute to the lack of regeneration of CNS axons following damage. The contrary functions of the tenascins have been localized to the different structural domains of the protein. However, little is known concerning the influence of the carbohydrate conjugated to the many potential sites for N- and O-glycosylation (10-120% by weight). As a first analytical requirement, we show that >80% of the N-glycans in tenascin-R are neutral and dominated by complex biantennary structures. These display the "brain-type” characteristics of outer-arm- and core-fucosylation, a bisecting N-acetylglucosamine and, significantly, an abundance of antennae truncation. In some structures, truncation resulted in only a single mannose residue remaining on the 3-arm, a particularly unusual consequence of the N-glycan processing pathway. In contrast to brain tissue, hybrid and oligomannosidic N-glycans were either absent or in low abundance. A high relative abundance of O-linked sialylated glycans was found. This was associated with a significant potential for O-linked glycosylation sites and multivalent display of the sialic acid residues. These O-glycans were dominated by the disialylated structure, NeuAcα2-3Galβ1-3(NeuAcα2-6)GalNAc. The possibility that these O-glycans enable tenascin-R to interact in the CNS either with the myelin associated glycoprotein or with sialoadhesin on activated microglia is discussed