TY - JOUR
T1 - Effects of altered sialic acid biosynthesis on N-linked glycan branching and cell surface interactions
AU - Pham, Nam D.
AU - Pang, Poh Choo
AU - Krishnamurthy, Soumya
AU - Wands, Amberlyn M.
AU - Grassi, Paola
AU - Dell, Anne
AU - Haslam, Stuart M.
AU - Kohler, Jennifer J.
N1 - Funding Information:
This work was supported, in whole or in part, by National Institutes of Health Grant R01GM090271. This work was also supported by Cancer Prevention and Research Institute of Texas (RP110080), the Welch Foundation (I-1686), and Grants BB/K016164/1 and BB/F008309/1 from the Biotechnology and Biological Sciences Research Council (to A. D. and S. M. H.). The authors declare that they have no conflicts of interest with the contents of this article. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Author’s Choice-Final version free via Creative Commons CC-BY license. 1 Supported by National Institutes of Health Predoctoral Fellowship F30AG040909. Acknowledgments-We thank Linda Baum and Mabel Pang (UCLA) for sharing the biotinylated galectin-1. Microarray analysis was performed by the UT Southwestern Genomics and Microarray Core Facility.
PY - 2017/6/9
Y1 - 2017/6/9
N2 - GNE (UDP-GlcNAc 2-epimerase/ManNAc kinase) myopathy is a rare muscle disorder associated with aging and is related to sporadic inclusion body myositis, the most common acquired muscle disease of aging. Although the cause of sporadic inclusion body myositis is unknown, GNE myopathy is associated with mutations in GNE. GNE harbors two enzymatic activities required for biosynthesis of sialic acid in mammalian cells. Mutations to both GNE domains are linked to GNE myopathy. However, correlation between mutation-associated reductions in sialic acid production and disease severity is imperfect. To investigate other potential effects of GNE mutations, we compared sialic acid production in cell lines expressing wild type or mutant forms of GNE. Although we did not detect any differences attributable to disease-associated mutations, lectin binding and mass spectrometry analysis revealed that GNE deficiency is associated with unanticipated effects on the structure of cell-surface glycans. In addition to exhibiting low levels of sialylation, GNE-deficient cells produced distinct N-linked glycan structures with increased branching and extended poly-Nacetyllactosamine. GNE deficiency may affect levels of UDPGlcNAc, a key metabolite in the nutrient-sensing hexosamine biosynthetic pathway, but this modest effect did not fully account for the change in N-linked glycan structure. Furthermore, GNE deficiency and glucose supplementation acted independently and additively to increaseN-linked glycan branching. Notably, N-linked glycans produced by GNE-deficient cells displayed enhanced binding to galectin-1, indicating that changes inGNEactivity can alter affinity of cell-surface glycoproteins for the galectin lattice. These findings suggest an unanticipated mechanism by which GNE activity might affect signaling through cell-surface receptors.
AB - GNE (UDP-GlcNAc 2-epimerase/ManNAc kinase) myopathy is a rare muscle disorder associated with aging and is related to sporadic inclusion body myositis, the most common acquired muscle disease of aging. Although the cause of sporadic inclusion body myositis is unknown, GNE myopathy is associated with mutations in GNE. GNE harbors two enzymatic activities required for biosynthesis of sialic acid in mammalian cells. Mutations to both GNE domains are linked to GNE myopathy. However, correlation between mutation-associated reductions in sialic acid production and disease severity is imperfect. To investigate other potential effects of GNE mutations, we compared sialic acid production in cell lines expressing wild type or mutant forms of GNE. Although we did not detect any differences attributable to disease-associated mutations, lectin binding and mass spectrometry analysis revealed that GNE deficiency is associated with unanticipated effects on the structure of cell-surface glycans. In addition to exhibiting low levels of sialylation, GNE-deficient cells produced distinct N-linked glycan structures with increased branching and extended poly-Nacetyllactosamine. GNE deficiency may affect levels of UDPGlcNAc, a key metabolite in the nutrient-sensing hexosamine biosynthetic pathway, but this modest effect did not fully account for the change in N-linked glycan structure. Furthermore, GNE deficiency and glucose supplementation acted independently and additively to increaseN-linked glycan branching. Notably, N-linked glycans produced by GNE-deficient cells displayed enhanced binding to galectin-1, indicating that changes inGNEactivity can alter affinity of cell-surface glycoproteins for the galectin lattice. These findings suggest an unanticipated mechanism by which GNE activity might affect signaling through cell-surface receptors.
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U2 - 10.1074/jbc.M116.764597
DO - 10.1074/jbc.M116.764597
M3 - Article
C2 - 28424265
AN - SCOPUS:85020621098
SN - 0021-9258
VL - 292
SP - 9637
EP - 9651
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 23
ER -