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Hirata E, Sakata KT, Dearden GI, Noor F, Menon I, Chiduza GN, Menon AK. Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.03.587922. [PMID: 38617304 PMCID: PMC11014557 DOI: 10.1101/2024.04.03.587922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
The oligosaccharide needed for protein N-glycosylation is assembled on a lipid carrier via a multi-step pathway. Synthesis is initiated on the cytoplasmic face of the endoplasmic reticulum (ER) and completed on the luminal side after transbilayer translocation of a heptasaccharide lipid intermediate. More than 30 Congenital Disorders of Glycosylation (CDGs) are associated with this pathway, including RFT1-CDG which results from defects in the membrane protein Rft1. Rft1 is essential for the viability of yeast and mammalian cells and was proposed as the transporter needed to flip the heptasaccharide lipid intermediate across the ER membrane. However, other studies indicated that Rft1 is not required for heptasaccharide lipid flipping in microsomes or unilamellar vesicles reconstituted with ER membrane proteins, nor is it required for the viability of at least one eukaryote. It is therefore not known what essential role Rft1 plays in N-glycosylation. Here, we present a molecular characterization of human Rft1, using yeast cells as a reporter system. We show that it is a multi-spanning membrane protein located in the ER, with its N and C-termini facing the cytoplasm. It is not N-glycosylated. The majority of RFT1-CDG mutations map to highly conserved regions of the protein. We identify key residues that are important for Rft1's ability to support N-glycosylation and cell viability. Our results provide a necessary platform for future work on this enigmatic protein.
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Affiliation(s)
- Eri Hirata
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Ken-taro Sakata
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Grace I. Dearden
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Faria Noor
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Indu Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - George N. Chiduza
- Structure and Function of Biological Membranes - Chemistry Department, Université Libre de Bruxelles - Campus Plaine, 1050 Brussels, Belgium
| | - Anant K. Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
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Yale AR, Kim E, Gutierrez B, Hanamoto JN, Lav NS, Nourse JL, Salvatus M, Hunt RF, Monuki ES, Flanagan LA. Regulation of neural stem cell differentiation and brain development by MGAT5-mediated N-glycosylation. Stem Cell Reports 2023:S2213-6711(23)00141-8. [PMID: 37172586 DOI: 10.1016/j.stemcr.2023.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 04/13/2023] [Accepted: 04/17/2023] [Indexed: 05/15/2023] Open
Abstract
Undifferentiated neural stem and progenitor cells (NSPCs) encounter extracellular signals that bind plasma membrane proteins and influence differentiation. Membrane proteins are regulated by N-linked glycosylation, making it possible that glycosylation plays a critical role in cell differentiation. We assessed enzymes that control N-glycosylation in NSPCs and found that loss of the enzyme responsible for generating β1,6-branched N-glycans, N-acetylglucosaminyltransferase V (MGAT5), led to specific changes in NSPC differentiation in vitro and in vivo. Mgat5 homozygous null NSPCs in culture formed more neurons and fewer astrocytes compared with wild-type controls. In the brain cerebral cortex, loss of MGAT5 caused accelerated neuronal differentiation. Rapid neuronal differentiation led to depletion of cells in the NSPC niche, resulting in a shift in cortical neuron layers in Mgat5 null mice. Glycosylation enzyme MGAT5 plays a critical and previously unrecognized role in cell differentiation and early brain development.
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Affiliation(s)
- Andrew R Yale
- Department of Anatomy & Neurobiology, University of California Irvine, Irvine, CA 92697, USA; Department of Neurology, University of California Irvine, Irvine, CA 92697, USA; Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA
| | - Estelle Kim
- Department of Neurology, University of California Irvine, Irvine, CA 92697, USA; Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA
| | - Brenda Gutierrez
- Department of Anatomy & Neurobiology, University of California Irvine, Irvine, CA 92697, USA; Department of Neurology, University of California Irvine, Irvine, CA 92697, USA; Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA
| | - J Nicole Hanamoto
- Department of Neurology, University of California Irvine, Irvine, CA 92697, USA; Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA
| | - Nicole S Lav
- Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA
| | - Jamison L Nourse
- Department of Neurology, University of California Irvine, Irvine, CA 92697, USA; Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA
| | - Marc Salvatus
- Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA
| | - Robert F Hunt
- Department of Anatomy & Neurobiology, University of California Irvine, Irvine, CA 92697, USA; Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA
| | - Edwin S Monuki
- Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA; Department of Pathology & Laboratory Medicine, University of California Irvine, Irvine, CA 92697, USA
| | - Lisa A Flanagan
- Department of Anatomy & Neurobiology, University of California Irvine, Irvine, CA 92697, USA; Department of Neurology, University of California Irvine, Irvine, CA 92697, USA; Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697, USA; Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA.
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Glycomic and Glycoproteomic Techniques in Neurodegenerative Disorders and Neurotrauma: Towards Personalized Markers. Cells 2022; 11:cells11030581. [PMID: 35159390 PMCID: PMC8834236 DOI: 10.3390/cells11030581] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/22/2022] [Accepted: 02/03/2022] [Indexed: 12/16/2022] Open
Abstract
The proteome represents all the proteins expressed by a genome, a cell, a tissue, or an organism at any given time under defined physiological or pathological circumstances. Proteomic analysis has provided unparalleled opportunities for the discovery of expression patterns of proteins in a biological system, yielding precise and inclusive data about the system. Advances in the proteomics field opened the door to wider knowledge of the mechanisms underlying various post-translational modifications (PTMs) of proteins, including glycosylation. As of yet, the role of most of these PTMs remains unidentified. In this state-of-the-art review, we present a synopsis of glycosylation processes and the pathophysiological conditions that might ensue secondary to glycosylation shortcomings. The dynamics of protein glycosylation, a crucial mechanism that allows gene and pathway regulation, is described. We also explain how-at a biomolecular level-mutations in glycosylation-related genes may lead to neuropsychiatric manifestations and neurodegenerative disorders. We then analyze the shortcomings of glycoproteomic studies, putting into perspective their downfalls and the different advanced enrichment techniques that emanated to overcome some of these challenges. Furthermore, we summarize studies tackling the association between glycosylation and neuropsychiatric disorders and explore glycoproteomic changes in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington disease, multiple sclerosis, and amyotrophic lateral sclerosis. We finally conclude with the role of glycomics in the area of traumatic brain injury (TBI) and provide perspectives on the clinical application of glycoproteomics as potential diagnostic tools and their application in personalized medicine.
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Increased B4GALT1 expression is associated with platelet surface galactosylation and thrombopoietin plasma levels in MPNs. Blood 2021; 137:2085-2089. [PMID: 33238000 DOI: 10.1182/blood.2020007265] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 11/09/2020] [Indexed: 12/31/2022] Open
Abstract
Aberrant megakaryopoiesis is a hallmark of the myeloproliferative neoplasms (MPNs), a group of clonal hematological malignancies originating from hematopoietic stem cells, leading to an increase in mature blood cells in the peripheral blood. Sialylated derivatives of the glycan structure β4-N-acetyllactosamine (Galβ1,4GlcNAc or type-2 LacNAc, hereafter referred to as LacNAc) regulate platelet life span, hepatic thrombopoietin (TPO) production, and thrombopoiesis. We found increased TPO plasma levels in MPNs with high allele burden of the mutated clones. Remarkably, platelets isolated from MPNs had a significant increase in LacNAc expression that correlated with the high allele burden regardless of the underlying identified mutation. Megakaryocytes derived in vitro from these patients showed an increased expression of the B4GALT1 gene encoding β-1,4-galactosyltransferase 1 (β4GalT1). Consistently, megakaryocytes from MPN showed increased LacNAc expression relative to healthy controls, which was counteracted by the treatment with a Janus kinase 1/2 inhibitor. Altered expression of B4GALT1 in mutant megakaryocytes can lead to the production of platelets with aberrant galactosylation, which in turn promote hepatic TPO synthesis regardless of platelet mass. Our findings provide a new paradigm for understanding aberrant megakaryopoiesis in MPNs and identify β4GalT1 as a potential actionable target for therapy.
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Yale AR, Nourse JL, Lee KR, Ahmed SN, Arulmoli J, Jiang AYL, McDonnell LP, Botten GA, Lee AP, Monuki ES, Demetriou M, Flanagan LA. Cell Surface N-Glycans Influence Electrophysiological Properties and Fate Potential of Neural Stem Cells. Stem Cell Reports 2018; 11:869-882. [PMID: 30197120 PMCID: PMC6178213 DOI: 10.1016/j.stemcr.2018.08.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 08/10/2018] [Accepted: 08/11/2018] [Indexed: 01/10/2023] Open
Abstract
Understanding the cellular properties controlling neural stem and progenitor cell (NSPC) fate choice will improve their therapeutic potential. The electrophysiological measure whole-cell membrane capacitance reflects fate bias in the neural lineage but the cellular properties underlying membrane capacitance are poorly understood. We tested the hypothesis that cell surface carbohydrates contribute to NSPC membrane capacitance and fate. We found NSPCs differing in fate potential express distinct patterns of glycosylation enzymes. Screening several glycosylation pathways revealed that the one forming highly branched N-glycans differs between neurogenic and astrogenic populations of cells in vitro and in vivo. Enhancing highly branched N-glycans on NSPCs significantly increases membrane capacitance and leads to the generation of more astrocytes at the expense of neurons with no effect on cell size, viability, or proliferation. These data identify the N-glycan branching pathway as a significant regulator of membrane capacitance and fate choice in the neural lineage.
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Affiliation(s)
- Andrew R Yale
- Department of Anatomy & Neurobiology, University of California, Irvine, Irvine, CA 92697, USA; Department of Neurology, University of California, Irvine, Irvine, CA 92697, USA; Sue & Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA 92697, USA
| | - Jamison L Nourse
- Department of Neurology, University of California, Irvine, Irvine, CA 92697, USA; Sue & Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA 92697, USA
| | - Kayla R Lee
- Department of Neurology, University of California, Irvine, Irvine, CA 92697, USA; Sue & Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA 92697, USA
| | - Syed N Ahmed
- Department of Neurology, University of California, Irvine, Irvine, CA 92697, USA; Sue & Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA 92697, USA
| | - Janahan Arulmoli
- Sue & Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA 92697, USA; Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA
| | - Alan Y L Jiang
- Sue & Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA 92697, USA; Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA
| | - Lisa P McDonnell
- Department of Neurology, University of California, Irvine, Irvine, CA 92697, USA; Sue & Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA 92697, USA
| | - Giovanni A Botten
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Abraham P Lee
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA
| | - Edwin S Monuki
- Sue & Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA 92697, USA; Department of Pathology and Laboratory Medicine, University of California, Irvine, Irvine, CA 92697, USA
| | - Michael Demetriou
- Department of Neurology, University of California, Irvine, Irvine, CA 92697, USA; Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA 92697, USA
| | - Lisa A Flanagan
- Department of Anatomy & Neurobiology, University of California, Irvine, Irvine, CA 92697, USA; Department of Neurology, University of California, Irvine, Irvine, CA 92697, USA; Sue & Bill Gross Stem Cell Research Center, University of California, Irvine, Irvine, CA 92697, USA; Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA.
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Alteration of N-glycans and expression of their related glycogenes in the epithelial-mesenchymal transition of HCV29 bladder epithelial cells. Molecules 2014; 19:20073-90. [PMID: 25470275 PMCID: PMC6271757 DOI: 10.3390/molecules191220073] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 11/23/2014] [Accepted: 11/24/2014] [Indexed: 11/16/2022] Open
Abstract
The epithelial-mesenchymal transition (EMT) is an essential step in the proliferation and metastasis of solid tumor cells, and glycosylation plays a crucial role in the EMT process. Certain aberrant glycans have been reported as biomarkers during bladder cancer progression, but global variation of N-glycans in this type of cancer has not been previously studied. We examined the profiles of N-glycan and glycogene expression in transforming growth factor-beta (TGFβ)-induced EMT using non-malignant bladder transitional epithelium HCV29 cells. These expression profiles were analyzed by mass spectrometry, lectin microarray analysis, and GlycoV4 oligonucleotide microarray analysis, and confirmed by lectin histochemistry and real-time RT-PCR. The expression of 5 N-glycan-related genes were notably altered in TGFβ-induced EMT. In particular, reduced expression of glycogene man2a1, which encodes α-mannosidase 2, contributed to the decreased proportions of bi-, tri- and tetra-antennary complex N-glycans, and increased expression of hybrid-type N-glycans. Decreased expression of fuca1 gene, which encodes Type 1 α-L-fucosidase, contributed to increased expression of fucosylated N-glycans in TGFβ-induced EMT. Taken together, these findings clearly demonstrate the involvement of aberrant N-glycan synthesis in EMT in these cells. Integrated glycomic techniques as described here will facilitate discovery of glycan markers and development of novel diagnostic and therapeutic approaches to bladder cancer.
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Lim JM, Wollaston-Hayden EE, Teo CF, Hausman D, Wells L. Quantitative secretome and glycome of primary human adipocytes during insulin resistance. Clin Proteomics 2014; 11:20. [PMID: 24948903 PMCID: PMC4055909 DOI: 10.1186/1559-0275-11-20] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 02/04/2014] [Indexed: 01/04/2023] Open
Abstract
Adipose tissue is both an energy storage depot and an endocrine organ. The impaired regulation of the secreted proteins of adipose tissue, known as adipocytokines, observed during obesity contributes to the onset of whole-body insulin resistance and the pathobiology of type 2 diabetes mellitus (T2DM). In addition, the global elevation of the intracellular glycosylation of proteins by O-linked β-N-acetylglucosamine (O-GlcNAc) via either genetic or pharmacological methods is sufficient to induce insulin resistance in both cultured cells and animal models. The elevation of global O-GlcNAc levels is associated with the altered expression of many adipocytokines. We have previously characterized the rodent adipocyte secretome during insulin sensitive and insulin resistant conditions. Here, we characterize and quantify the secretome and glycome of primary human adipocytes during insulin responsive and insulin resistant conditions generated by the classical method of hyperglycemia and hyperinsulinemia or by the pharmacological manipulation of O-GlcNAc levels. Using a proteomic approach, we identify 190 secreted proteins and report a total of 20 up-regulated and 6 down-regulated proteins that are detected in both insulin resistant conditions. Moreover, we apply glycomic techniques to examine (1) the sites of N-glycosylation on secreted proteins, (2) the structures of complex N- and O-glycans, and (3) the relative abundance of complex N- and O-glycans structures in insulin responsive and insulin resistant conditions. We identify 91 N-glycosylation sites derived from 51 secreted proteins, as well as 155 and 29 released N- and O-glycans respectively. We go on to quantify many of the N- and O-glycan structures between insulin responsive and insulin resistance conditions demonstrating no significant changes in complex glycosylation in the time frame for the induction of insulin resistance. Thus, our data support that the O-GlcNAc modification is involved in the regulation of adipocytokine secretion upon the induction of insulin resistance in human adipocytes.
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Affiliation(s)
- Jae-Min Lim
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, 30602-4712 Athens, Georgia ; Department of Chemistry, The University of Georgia, 30602 Athens, Georgia ; Department of Chemistry, Changwon National University, Changwon, Gyeongnam 641-773, South Korea
| | - Edith E Wollaston-Hayden
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, 30602-4712 Athens, Georgia ; Department of Biochemistry and Molecular Biology, The University of Georgia, 30602 Athens, Georgia
| | - Chin Fen Teo
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, 30602-4712 Athens, Georgia ; Department of Biochemistry and Molecular Biology, The University of Georgia, 30602 Athens, Georgia
| | - Dorothy Hausman
- Department of Foods and Nutrition, The University of Georgia, 30602 Athens, Georgia
| | - Lance Wells
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, 30602-4712 Athens, Georgia ; Department of Chemistry, The University of Georgia, 30602 Athens, Georgia ; Department of Biochemistry and Molecular Biology, The University of Georgia, 30602 Athens, Georgia
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Samways DSK. Applications for mass spectrometry in the study of ion channel structure and function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 806:237-61. [PMID: 24952185 DOI: 10.1007/978-3-319-06068-2_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Ion channels are intrinsic membrane proteins that form gated ion-permeable pores across biological membranes. Depending on the type, ion channels exhibit sensitivities to a diverse range of stimuli including changes in membrane potential, binding by diffusible ligands, changes in temperature and direct mechanical force. The purpose of these proteins is to facilitate the passive diffusion of ions down their respective electrochemical gradients into and out of the cell, and between intracellular compartments. In doing so, ion channels can affect transmembrane potentials and regulate the intracellular homeostasis of the important second messenger, Ca(2+). The ion channels of the plasma membrane are of particular clinical interest due to their regulation of cell excitability and cytosolic Ca(2+) levels, and the fact that they are most amenable to manipulation by exogenously applied drugs and toxins. A critical step in improving the pharmacopeia of chemicals available that influence the activity of ion channels is understanding how their three-dimensional structure imparts function. Here, progress has been slow relative to that for soluble protein structures in large part due to the limitations of applying conventional structure determination methods, such as X-ray crystallography, nuclear magnetic resonance imaging, and mass spectrometry, to membrane proteins. Although still an underutilized technique in the assessment of membrane protein structure, recent advances have pushed mass spectrometry to the fore as an important complementary approach to studying the structure and function of ion channels. In addition to revealing the subtle conformational changes in ion channel structure that accompany gating and permeation, mass spectrometry is already being used effectively for identifying tissue-specific posttranslational modifications and mRNA splice variants. Furthermore, the use of mass spectrometry for high-throughput proteomics analysis, which has proven so successful for soluble proteins, is already providing valuable insight into the functional interactions of ion channels within the context of the macromolecular-signaling complexes that they inhabit in vivo. In this chapter, the potential for mass spectrometry as a complementary approach to the study of ion channel structure and function will be reviewed with examples of its application.
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Affiliation(s)
- Damien S K Samways
- Department of Biology, Clarkson University, 8 Clarkson Avenue, Potsdam, NY, 13699, USA,
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Zhu J, Yan J, Thornhill WB. N-glycosylation promotes the cell surface expression of Kv1.3 potassium channels. FEBS J 2012; 279:2632-44. [PMID: 22613618 DOI: 10.1111/j.1742-4658.2012.08642.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The voltage-gated potassium channel Kv1.3 plays an essential role in modulating membrane excitability in many cell types. Kv1.3 is a heavily glycosylated membrane protein. Two successive N-glycosylation consensus sites, N228NS and N229ST, are present on the S1-S2 linker of rat Kv1.3. Our data suggest that Kv1.3 contains only one N-glycan and it is predominantly attached to N229 in the S1-S2 extracellular linker. Preventing N-glycosylation of Kv1.3 significantly decreased its surface protein level and surface conductance density level, which were ∼ 49% and ∼ 46% respectively of the level of wild type. Supplementation of N-acetylglucosamine (GlcNAc), l-fucose or N-acetylneuraminic acid to the culture medium promoted Kv1.3 surface protein expression, whereas supplementation of d-glucose, d-mannose or d-galactose did not. Among the three effective monosaccharides/derivatives, adding GlcNAc appeared to reduce sialic acid content and increase the degree of branching in the N-glycan of Kv1.3, suggesting that the N-glycan structure and composition had changed. Furthermore, the cell surface half-life of the Kv1.3 surface protein was increased upon GlcNAc supplementation, indicating that it had decreased internalization. The GlcNAc effect appears to apply mainly to membrane proteins containing complex type N-glycans. Thus, N-glycosylation promotes Kv1.3 cell surface expression; supplementation of GlcNAc increased Kv1.3 surface protein level and decreased its internalization, presumably by a combined effect of decreased branch size and increased branching of the N-glycan.
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Affiliation(s)
- Jing Zhu
- Department of Biological Sciences and Center for Cancer, Genetic Diseases and Gene Regulation, Fordham University, Bronx, NY, USA
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SIMPSON GREGORYIC, SHARKEY LESLIEC, FRAY JOHN. ALTERED ABUNDANCE OF MESSENGER RNA TRANSCRIPTS WHOSE PRODUCTS HAVE MEMBRANE ATTACHMENT SITES IN PREGNANCY-INDUCED HYPERTENSION. J BIOL SYST 2012. [DOI: 10.1142/s021833900200069x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Pregnancy-induced hypertensive disorders (PIH) are leading causes of maternal mortality. Although the mechanism responsible for initiating and maintaining the disorder is unproven, physiologic molecular attachments in kidney and placenta play a role. The SHHF/Mcc-facp (SHHF) rat has features of the disorder, including abnormal placenta gene expression. To gain a molecular understanding of the gene expression profile associated with PIH, kidneys and placentas of SHHF rats at gestation day 20 were compared to WKY controls using microarray technology. We report that SHHF rats have spontaneous PIH, elevated total placenta weights, and reduced total pup weights than WKY controls and that they also have greater total number of mRNA transcripts expressed in placenta. Kidneys of SHHF rats, on the other hand, not only expressed disproportionately more predicted gene products with attachment sites such as RGD motifs, N-glycosylation sites, and N-myristoylation sites they also responded more profoundly to oral administration of L-arginine. We conclude that the increased abundance of transcripts whose products engage in posttranslational attachments using RGD motifs, N-glycosylation sites, and N-myristoylation sites and the reversal of these increases by oral administration of L-arginine suggests that NO may be of importance in PIH at the level of molecular attachments.
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Affiliation(s)
- GREGORY I. C. SIMPSON
- Genomic Physiology Group, Cellular and Molecular Physiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
- Veterinary Services Division, Ministry of Agriculture, Kingston, Jamaica
| | - LESLIE C. SHARKEY
- Department of Biomedical Sciences, Tufts University School of Veterinary Medicine, Grafton, Massachusetts, USA
| | - JOHN FRAY
- Genomic Physiology Group, Cellular and Molecular Physiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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Burglen L, Chantot-Bastaraud S, Garel C, Milh M, Touraine R, Zanni G, Petit F, Afenjar A, Goizet C, Barresi S, Coussement A, Ioos C, Lazaro L, Joriot S, Desguerre I, Lacombe D, des Portes V, Bertini E, Siffroi JP, de Villemeur TB, Rodriguez D. Spectrum of pontocerebellar hypoplasia in 13 girls and boys with CASK mutations: confirmation of a recognizable phenotype and first description of a male mosaic patient. Orphanet J Rare Dis 2012; 7:18. [PMID: 22452838 PMCID: PMC3351739 DOI: 10.1186/1750-1172-7-18] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 03/27/2012] [Indexed: 11/10/2022] Open
Abstract
Background Pontocerebellar hypoplasia (PCH) is a heterogeneous group of diseases characterized by lack of development and/or early neurodegeneration of cerebellum and brainstem. According to clinical features, seven subtypes of PCH have been described, PCH type 2 related to TSEN54 mutations being the most frequent. PCH is most often autosomal recessive though de novo anomalies in the X-linked gene CASK have recently been identified in patients, mostly females, presenting with intellectual disability, microcephaly and PCH (MICPCH). Methods Fourteen patients (12 females and two males; aged 16 months-14 years) presenting with PCH at neuroimaging and with clinical characteristics unsuggestive of PCH1 or PCH2 were included. The CASK gene screening was performed using Array-CGH and sequencing. Clinical and neuroradiological features were collected. Results We observed a high frequency of patients with a CASK mutation (13/14). Ten patients (8 girls and 2 boys) had intragenic mutations and three female patients had a Xp11.4 submicroscopic deletion including the CASK gene. All were de novo mutations. Phenotype was variable in severity but highly similar among the 11 girls and was characterized by psychomotor retardation, severe intellectual disability, progressive microcephaly, dystonia, mild dysmorphism, and scoliosis. Other signs were frequently associated, such as growth retardation, ophthalmologic anomalies (glaucoma, megalocornea and optic atrophy), deafness and epilepsy. As expected in an X-linked disease manifesting mainly in females, the boy hemizygous for a splice mutation had a very severe phenotype with nearly no development and refractory epilepsy. We described a mild phenotype in a boy with a mosaic truncating mutation. We found some degree of correlation between severity of the vermis hypoplasia and clinical phenotype. Conclusion This study describes a new series of PCH female patients with CASK inactivating mutations and confirms that these patients have a recognizable although variable phenotype consisting of a specific form of pontocerebellar hypoplasia. In addition, we report the second male patient to present with a severe MICPCH phenotype and a de novo CASK mutation and describe for the first time a mildly affected male patient harboring a mosaic mutation. In our reference centre, CASK related PCH is the second most frequent cause of PCH. The identification of a de novo mutation in these patients enables accurate and reassuring genetic counselling.
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Affiliation(s)
- Lydie Burglen
- Centre de Référence Maladies Rares « malformations et maladies congénitales du cervelet », Hôpital Trousseau-Paris, CHU de Lyon, CHU de Lille, Paris, France.
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Labat-Robert J, Robert L. Fifty years of structural glycoproteins. ACTA ACUST UNITED AC 2012; 60:66-75. [PMID: 22227294 DOI: 10.1016/j.patbio.2011.11.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 10/30/2011] [Indexed: 10/14/2022]
Abstract
During decades preceding and following the last war, a favourite subject of biochemists was to study glycoproteins. One class of these substances, found in connective tissues were characterised as polysaccharides, most of them found to be linked to proteins, designated later as glycosaminoglycans and proteoglycans. Another family of glycoconjugates represented epithelial mucins as found in the gastro-intestinal and respiratory tracts and conduits. A third family of glycoconjugates is represented by circulating glycoproteins isolated from the blood plasma, mostly studied by medical biochemists in relation to pathological conditions comprising those increasing during the inflammatory reaction: acute phase glycoproteins. Their study suggested that they might be derived from connective tissues. Although inflammatory glycoproteins derive mostly from the liver, the possibility of connective tissue origin of glycoproteins remained open. Using cornea, an avascular tissue, we could show that connective tissues also synthesize glycoproteins. We proposed to designate them "structural glycoproteins" (SGP-s) to distinguish them from circulating, blood-born glycoproteins coming from the liver. They play locally "structural" roles in connective tissues where they are synthesized. Soon after fibronectin was identified and shown to mediate cell-matrix interactions. A large family of glycoproteins were then isolated from a variety of sources, cells, tissues others than liver, confirming our original hypothesis. The first experiments on these glycoproteins were published from 1961/1962 giving the opportunity to recapitulate this biochemical adventure 50 years later, together with the celebration of the foundation of the first connective tissue society in Europe, as described in the first article in this issue.
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Affiliation(s)
- J Labat-Robert
- Laboratoire de recherche ophtalmologique, hôpital Hôtel-Dieu, université Paris-5, 1, place du Parvis-Notre-Dame, 75181 Paris cedex 04, France
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13
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Abstract
Glycans as Biomarkers: Status and PerspectivesProtein glycosylation is a ubiquitous and complex co- and post-translational modification leading to glycan formation, i.e. oligosaccharide chains covalently attached to peptide backbones. The significance of changes in glycosylation for the beginning, progress and outcome of different human diseases is widely recognized. Thus, glycans are considered as unique structures to diagnose, predict susceptibility to and monitor the progression of disease. In the »omics« era, the glycome, a glycan analogue of the proteome and genome, holds considerable promise as a source of new biomarkers. In the design of a strategy for biomarker discovery, new principles and platforms for the analysis of relatively small amounts of numerous glycoproteins are needed. Emerging glycomics technologies comprising different types of mass spectrometry and affinity-based arrays are next in line to deliver new analytical procedures in the field of biomarkers. Screening different types of glycomolecules, selection of differentially expressed components, their enrichment and purification or identification are the most challenging parts of experimental and clinical glycoproteomics. This requires large-scale technologies enabling high sensitivity, proper standardization and validation of the methods to be used. Further progress in the field of applied glycoscience requires an integrated systematic approach in order to explore properly all opportunities for disease diagnosis.
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14
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Skropeta D. The effect of individual N-glycans on enzyme activity. Bioorg Med Chem 2009; 17:2645-53. [PMID: 19285412 DOI: 10.1016/j.bmc.2009.02.037] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2008] [Revised: 02/11/2009] [Accepted: 02/13/2009] [Indexed: 01/08/2023]
Abstract
In a series of investigations, N-glycosylation has proven to be a key determinant of enzyme secretion, activity, binding affinity and substrate specificity, enabling a protein to fine-tune its activity. In the majority of cases elimination of all putative N-glycosylation sites of an enzyme results in significantly reduced protein secretion levels, while removal of individual N-glycosylation sites often leads to the expression of active enzymes showing markedly reduced catalytic activity, with the decreased activity often commensurate with the number of glycosylation sites available, and the fully deglycosylated enzymes showing only minimal activity relative to their glycosylated counterparts. On the other hand, several cases have also recently emerged where deglycosylation of an enzyme results in significantly increased catalytic activity, binding affinity and altered substrate specificity, highlighting the very unique and diverse roles that individual N-glycans play in regulating enzyme function.
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Affiliation(s)
- Danielle Skropeta
- School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
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15
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Schachter H. The functions of paucimannose N-glycans in Caenorhabditis elegans. TRENDS GLYCOSCI GLYC 2009. [DOI: 10.4052/tigg.21.131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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16
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Glycosylation diseases: quo vadis? Biochim Biophys Acta Mol Basis Dis 2008; 1792:925-30. [PMID: 19061954 DOI: 10.1016/j.bbadis.2008.11.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 11/03/2008] [Accepted: 11/06/2008] [Indexed: 12/29/2022]
Abstract
About 250 to 500 glycogenes (genes that are directly involved in glycan assembly) are in the human genome representing about 1-2% of the total genome. Over 40 human congenital diseases associated with glycogene mutations have been described to date. It is almost certain that the causative glycogene mutations for many more congenital diseases remain to be discovered. Some glycogenes are involved in the synthesis of only a specific protein and/or a specific class of glycan whereas others play a role in the biosynthesis of more than one glycan class. Mutations in the latter type of glycogene result in complex clinical phenotypes that present difficult diagnostic problems to the clinician. In order to understand in biochemical terms the clinical signs and symptoms of a patient with a glycogene mutation, one must understand how the glycogene works. That requires, first of all, determination of the target protein or proteins of the glycogene followed by an understanding of the role, if any, of the glycogene-dependent glycan in the functions of the protein. Many glycogenes act on thousands of glycoproteins. There are unfortunately no general methods to identify all the potentially large number of glycogene target proteins and which of these proteins are responsible for the mutant phenotypes. Whereas biochemical methods have been highly successful in the discovery of glycogenes responsible for many congenital diseases, it has more recently been necessary to use other methods such as homozygosity mapping. Accurate diagnosis of many recently discovered diseases has become difficult and new diagnostic procedures must be developed. Last but not least is the lack of effective treatment for most of these children and of animal models that can be used to test new therapies.
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17
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Affiliation(s)
- Heather E. Murrey
- Division of Chemistry and Chemical Engineering and Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125
| | - Linda C. Hsieh-Wilson
- Division of Chemistry and Chemical Engineering and Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125
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18
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Qasba PK, Ramakrishnan B, Boeggeman E. Structure and function of beta -1,4-galactosyltransferase. Curr Drug Targets 2008; 9:292-309. [PMID: 18393823 DOI: 10.2174/138945008783954943] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Beta-1,4-galactosylransferase (beta4Gal-T1) participates in the synthesis of Galbeta1-4-GlcNAc-disaccharide unit of glycoconjugates. It is a trans-Golgi glycosyltransferase (Glyco-T) with a type II membrane protein topology, a short N-terminal cytoplasmic domain, a membrane-spanning region, as well as a stem and a C-terminal catalytic domain facing the trans-Golgi-lumen. Its hydrophobic membrane-spanning region, like that of other Glyco-T, has a shorter length compared to plasma membrane proteins, an important feature for its retention in the trans-Golgi. The catalytic domain has two flexible loops, a long and a small one. The primary metal binding site is located at the N-terminal hinge region of the long flexible loop. Upon binding of metal ion and sugar-nucleotide, the flexible loops undergo a marked conformational change, from an open to a closed conformation. Conformational change simultaneously creates at the C-terminal region of the flexible loop an oligosaccharide acceptor binding site that did not exist before. The loop acts as a lid covering the bound donor substrate. After completion of the transfer of the glycosyl unit to the acceptor, the saccharide product is ejected; the loop reverts to its native conformation to release the remaining nucleotide moiety. The conformational change in beta4Gal-T1 also creates the binding site for a mammary gland-specific protein, alpha-lactalbumin (LA), which changes the acceptor specificity of the enzyme toward glucose to synthesize lactose during lactation. The specificity of the sugar donor is generally determined by a few residues in the sugar-nucleotide binding pocket of Glyco-T, conserved among the family members from different species. Mutation of these residues has allowed us to design new and novel glycosyltransferases, with broader or requisite donor and acceptor specificities, and to synthesize specific complex carbohydrates as well as specific inhibitors for these enzymes.
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Affiliation(s)
- Pradman K Qasba
- Structural Glycobiology Section, CCRNP, NCI-Frederick, Building 469, Room 221, Frederick, Maryland 21702, USA.
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19
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Lewandrowski U, Zahedi RP, Moebius J, Walter U, Sickmann A. Enhanced N-glycosylation site analysis of sialoglycopeptides by strong cation exchange prefractionation applied to platelet plasma membranes. Mol Cell Proteomics 2007; 6:1933-41. [PMID: 17660510 DOI: 10.1074/mcp.m600390-mcp200] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Elucidation of post-translational modifications to proteins, such as glycosylations or phosphorylations, is one of the major issues concerning ongoing proteomics studies. To reduce general sample complexity, a necessary prerequisite is specific enrichment of peptide subsets prior to mass spectrometric sequencing. Regarding analysis of overall N-glycosylation sites in the past, this has been achieved by several approaches proving to be more or less complicated and specific. Here we present a novel strategy to target N-glycosylation sites with application to platelet membrane proteins. Initial aqueous two-phase partitioning for membrane enrichment and single step strong cation exchange-based purification of glycopeptides resulted in identification of 148 glycosylation sites on 79 different protein species. Although 69% of these sites were not annotated in the Swiss-Prot database before, a high number of 75% plasma membrane-localized proteins were analyzed. Furthermore miniaturizations and relative quantification are comprised in the developed method suggesting further use in other proteome projects. Results on platelet glycosylation sites may imply an impact on research of bleeding disorders as well as potential new functions in inflammation and immunoactivity.
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Affiliation(s)
- Urs Lewandrowski
- DFG Research Center for Experimental Biomedicine, University Würzburg, Versbacher Strasse 9, 97078 Würzburg, Germany
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20
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Marklová E, Albahri Z. Screening and diagnosis of congenital disorders of glycosylation. Clin Chim Acta 2007; 385:6-20. [PMID: 17716641 DOI: 10.1016/j.cca.2007.07.002] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 06/22/2007] [Accepted: 07/02/2007] [Indexed: 02/07/2023]
Abstract
The aim of this paper is to review the diagnostics of congenital disorders of glycosylation (CDG), an ever expanding group of diseases. Development delay, neurological, and other clinical abnormalities as well as various non-specific laboratory changes can lead to the first suspicion of the disease. Still common screening test for most CDG types, including CDG Ia, is isoelectric focusing/polyacrylamide gel electrophoresis (IEF). IEF demonstrates the hypoglycosylation of various glycoproteins, usually serum transferrin. Other methods, such as agarose electrophoresis, capillary electrophoresis, high-performance liquid chromatography, micro-column separation combined with turbidimetry, enzyme-(EIA) and radioimmunoassay (RIA) have also been used for screening. However, these methods do not recognize all CDG defects, so other approaches including analysis of membrane-linked markers and urine oligosaccharides should be taken. Confirmation of diagnosis and detailed CDG subtyping starts with thorough structure analysis of the affected lipid-linked oligosaccharide or protein-(peptide)-linked-glycan using metabolic labeling and various (possibly mass-spectrometry combined) techniques. Decreased enzyme activity in peripheral leukocytes/cultured fibroblasts or analysis of affected transporters and other functional proteins combined with identification of specific gene mutations confirm the diagnosis. Prenatal diagnosis, based on enzyme assay or mutation analysis, is also available. Peri-/post-mortem investigations of fatal cases are important for genetic counseling. Evaluation of various analytical approaches and proposed algorithms for investigation complete the review.
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Affiliation(s)
- Eliska Marklová
- Charles University, Faculty of Medicine, Department of Pediatrics, Hradec Králové, Czech Republic.
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21
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Angel PM, Lim JM, Wells L, Bergmann C, Orlando R. A potential pitfall in 18O-based N-linked glycosylation site mapping. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2007; 21:674-82. [PMID: 17279607 DOI: 10.1002/rcm.2874] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A common procedure for identifying N-linked glycosylation sites involves tryptic digestion of the glycoprotein, followed by the conversion of glycosylated asparagine residues into (18)O-labeled aspartic acids by PNGase F digestion in (18)O water. The 3 Da mass tag created by this process is readily observable by liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis, and is often used to identify the sites of N-linked glycosylation. While using this procedure, we noticed that 60% of the asparagines identified as being glycosylated were not part of the consensus sequence required for N-linked glycosylation, and thus were not biologically possible. Investigation into the source of this unacceptably high false positive rate demonstrated that even after reversed-phase cleanup and heat denaturation, the trypsin used for proteolysis was still active and led to the incorporation of (18)O into the C-termini of the peptides during the deglycosylation step. The resulting mass shift accounted for most of the false positive sites, as the database search algorithm confused it with an (18)O-labeled Asp residue near the C-terminus of a peptide. This problem can be overcome by eliminating trypsin from the solution prior to performing the deglycosylation process, by resuspending the peptides in natural abundance water following deglycosylation, or by allowing (18)O incorporation into the C-terminus as a variable modification during the database search. These methods have been demonstrated on a model protein, and are applicable to the analyses of glycoproteins that are digested with trypsin or another serine protease prior to enzymatic release of the carbohydrate side chains. This study should alert investigators in the field to this potential and unexpected pitfall and provide strategies to overcome this phenomenon.
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Affiliation(s)
- Peggi M Angel
- Complex Carbohydrate Research Center and the Departments of Biochemistry and Molecular Biology and Chemistry, University of Georgia, 315 Riverbend Road, Athens, GA 30302-4712, USA
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22
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Uccelletti D, Farina F, Rufini S, Magnelli P, Abeijon C, Palleschi C. The Kluyveromyces lactis alpha1,6-mannosyltransferase KlOch1p is required for cell-wall organization and proper functioning of the secretory pathway. FEMS Yeast Res 2006; 6:449-57. [PMID: 16630285 DOI: 10.1111/j.1567-1364.2006.00027.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Mutants of Kluyveromyces lactis denominated vga (vanadate glycosylation affected) bear various combinations of glycosylation and cell-wall defects. The vga3 mutation of K. lactis was mapped in the KlOCH1 gene, encoding the functional homologue of the Saccharomyces cerevisiaealpha1,6-mannosyltransferase. Quantitative analysis of cell-wall components indicated a noticeable increase of chitin and beta1,6-glucans and a severe decrease of mannoproteins in the mutant cells as compared with the wild-type counterparts. Fine-structure determination of the beta1,6-glucan polymer indicated that, in the vga3-1 strain, the beta1,6-glucans are shorter and have more branches than in the wild-type strain. This suggests that cell-wall remodelling changes take place in K. lactis in the presence of glycosylation defects. Moreover, the vga3 cells showed a significantly improved capability of secreting heterologous proteins. Such a capability, accompanied by the highly reduced N-glycosylation, may be of biotechnological interest, especially when hyper-glycosylation of recombinant products must be avoided.
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Affiliation(s)
- Daniela Uccelletti
- Department of Developmental and Cell Biology, University La Sapienza, Rome, Italy
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23
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Suzuki A. Genetic basis for the lack of N-glycolylneuraminic acid expression in human tissues and its implication to human evolution. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2006; 82:93-103. [PMID: 25873750 PMCID: PMC4323044 DOI: 10.2183/pjab.82.93] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Accepted: 03/13/2006] [Indexed: 05/17/2023]
Abstract
Sialic acid is a family of acidic monosaccharides and consists of over 30 derivatives. Two major derivatives are N-acetylneuraminic acid (NeuAc) and N-glycolylneuraminic acid (NeuGc), and the hydroxylation of CMP-NeuAc is the rate limiting reaction for the production of NeuGc. The hydroxylation was carried out by a complex formed with hydroxylase, cytochrome b5, and NADH-cytochrome b5 reductase. Mouse hydroxylase was purified from the cytosolic fraction of the liver and its cDNA was cloned. Normal human tissues do not contain NeuGc. Human hydroxylase cDNA was also cloned and the sequence revealed that human hydroxylase has 92 bp deletion. The deletion is the cause of defective expression of NeuGc in human. Chimpanzee has intact hydroxylase gene and the 92 bp deletion occurred after the divergence of human ancestor from chimpanzee ancestor. Biochemical and molecular biological studies on the biosynthesis of NeuGc and biological functions of NeuGc are reviewed.
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Affiliation(s)
- Akemi Suzuki
- Supra-Biomolecular System Research Group, RIKEN Frontier Research System, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan ()
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24
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Wada Y. Mass spectrometry for congenital disorders of glycosylation, CDG. J Chromatogr B Analyt Technol Biomed Life Sci 2006; 838:3-8. [PMID: 16517226 DOI: 10.1016/j.jchromb.2006.02.028] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2005] [Revised: 01/20/2006] [Accepted: 02/08/2006] [Indexed: 10/24/2022]
Abstract
Congenital disorders of glycosylation (CDG) constitute a group of diseases affecting N-linked glycosylation pathways. The classical type of CDG, now called CDG-I, results from deficiencies in the early glycosylation pathway for biosynthesis of lipid-linked oligosaccharide and its transfer to proteins in endoplasmic reticulum, while the CDG-II diseases are caused by defects in the subsequent processing steps. Mass spectrometry (MS) produced a milestone in CDG research, by localizing the CDG-I defect to the early glycosylation pathway in 1992. Currently, MS of transferrin, either by electrospray ionization or matrix-assisted laser desorption/ionization, plays the central role in laboratory screening of CDG-I. On the other hand, the glycopeptide analysis recently developed for site-specific glycans of glycoproteins allows detailed glycan analysis in a high throughput manner and will solve problems in CDG-II diagnosis. These techniques will facilitate studying CDG, a field now expanding to O-linked glycosylation and to acquired as well as inherited conditions that can affect protein glycosylation.
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Affiliation(s)
- Yoshinao Wada
- Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka 594-1101, Japan.
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25
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Parry S, Hadaschik D, Blancher C, Kumaran MK, Bochkina N, Morris HR, Richardson S, Aitman TJ, Gauguier D, Siddle K, Scott J, Dell A. Glycomics investigation into insulin action. Biochim Biophys Acta Gen Subj 2006; 1760:652-68. [PMID: 16473469 DOI: 10.1016/j.bbagen.2005.12.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 12/09/2005] [Accepted: 12/12/2005] [Indexed: 11/30/2022]
Abstract
Defects in glycosylation are becoming increasingly associated with a range of human diseases. In some cases, the disease is caused by the glycosylation defect, whereas in others, the aberrant glycosylation may be a consequence of the disease. The implementation of highly sensitive and rapid mass spectrometric screening strategies for profiling the glycans present in model biological systems is revealing valuable insights into disease phenotypes. In addition, glycan screening is proving useful in the analysis of knock-out mice where it is possible to assess the role of glycosyltransferases and glycosidases and what function they have at the cellular and whole organism level. In this study, we analysed the effect of insulin on the glycosylation of 3T3-L1 cells and the effect of insulin resistance on glycosylation in a mouse model. Transcription profiling of 3T3-L1 cells treated with and without insulin revealed expression changes of several glycogenes. In contrast, mass spectrometric screening analysis of the glycans from these cells revealed very similar profiles suggesting that any changes in glycosylation were most likely on specific proteins rather than a global phenomenon. A fat-fed versus carbohydrate-fed mouse insulin resistant model was analysed to test the consequences of chronic insulin resistance. Muscle and liver N-glycosylation profiles from these mice are reported.
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Affiliation(s)
- Simon Parry
- Division of Molecular Biosciences, Imperial College, London, South Kensington, UK
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26
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Hashii N, Kawasaki N, Itoh S, Hyuga M, Kawanishi T, Hayakawa T. Glycomic/glycoproteomic analysis by liquid chromatography/mass spectrometry: Analysis of glycan structural alteration in cells. Proteomics 2005; 5:4665-72. [PMID: 16281179 DOI: 10.1002/pmic.200401330] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The alteration of glycosyltransferase expression and the subsequent changes in oligosaccharide structures are reported in several diseases. The analysis of glycan structural alteration in glycoproteins is becoming increasingly important in the discovery of therapies and diagnostic markers. In this study, we propose a strategy for glycomic/glycoproteomic analysis based on oligosaccharide profiling by LC/MS followed by proteomic approaches, including 2-DE and 2-D lectin blot. As a model of aberrant cells, we used Chinese hamster ovary cells transfected with N-acetylglucosaminyltransferase III (GnT-III), which catalyzes the addition of a bisecting N-acetylglucosamine (GlcNAc) to beta-mannose of the mannosyl core of N-linked oligosaccharides. LC/MS equipped with a graphitized carbon column (GCC) enabled us to elucidate the structural alteration induced by the GnT-III expression. Using 2-D lectin blot followed by LC/MS/MS, the protein carrying an extra N-acetylhexosamine in cells transfected with GnT-III was successfully identified as integrin alpha3. Thus, oligosaccharide profiling by GCC-LC/MS followed by proteomic methods can be a powerful tool for glycomic/glycoproteomic analysis.
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Affiliation(s)
- Noritaka Hashii
- Division of Biological Chemistry and Biologicals, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
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27
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Schachter H. The search for glycan function: fucosylation of the TGF-beta1 receptor is required for receptor activation. Proc Natl Acad Sci U S A 2005; 102:15721-2. [PMID: 16249330 PMCID: PMC1276088 DOI: 10.1073/pnas.0507659102] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Harry Schachter
- Program in Structural Biology and Biochemistry, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, Canada M5G 1X8.
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28
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Sagi D, Kienz P, Denecke J, Marquardt T, Peter-Katalinić J. Glycoproteomics ofN-glycosylation by in-gel deglycosylation and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry mapping: Application to congenital disorders of glycosylation. Proteomics 2005; 5:2689-701. [PMID: 15912511 DOI: 10.1002/pmic.200401312] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A general strategy for the structural evaluation of N-glycosylation, a common post-translational protein modification, is presented. The methods for the release of N-linked glycans from the gel-separated proteins, their isolation, purification and matrix-assisted laser desorption/ionisation-mass spectrometry (MALDI-MS) analysis of their mixtures were optimised. Since many glycoproteins are available only at low quantities from sodium dodecyl sulphate-polyacrylamide gel electrophoresis or two-dimensional gels, high attention was paid to obtain N-glycan mixtures representing their actual composition in human plasma by in-gel deglycosylation. The relative sensitivity of solid MALDI matrices for MS analysis of acidic N-glycans was compared. The most favourable results for native acidic N-glycans were obtained with 2,4,6-trihydroxyacetophenone monohydrate/diammoniumcitrate as a matrix. This matrix provided good results for both neutral and acidic mixtures as well as for methylated N-glycans. In the second part of this paper the potential of such an optimised MS strategy alone or in combination with high pH anion-exchange chromatography profiling for the clinical diagnosis of congenital disorders of glycosylation is presented.
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Affiliation(s)
- Dijana Sagi
- Institute for Medical Physics and Biophysics, University of Münster, Münster, Germany
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29
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Aronica E, van Kempen AAMW, van der Heide M, Poll-The BT, van Slooten HJ, Troost D, Rozemuller-Kwakkel JM. Congenital disorder of glycosylation type Ia: a clinicopathological report of a newborn infant with cerebellar pathology. Acta Neuropathol 2005; 109:433-42. [PMID: 15714316 DOI: 10.1007/s00401-004-0975-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 12/06/2004] [Accepted: 12/06/2004] [Indexed: 12/11/2022]
Abstract
Congenital disorders of glycosylation (CDG) represent a newly delineated group of inherited multisystem disorders characterized by defective glycoprotein biosynthesis. In the present study we report and discuss the clinical and neuropathological findings in a newborn with CDG type Ia (CDG-Ia). The patient presented mild dysmorphic facial features, inverted nipples, progressive generalized edema, hypertrophic cardiomyopathy, hepatosplenomegaly, muscular hypotonia and had severe hypoalbuminemia. Deficiency of phosphomannomutase (PMM)-2 activity was detected. Molecular analysis showed V231M/T237R mutations of the PMM2 gene. Muscular biopsy, disclosed myopathic alterations with myofibrillar disarray by electron microscopy. The patient died at 1 month of age of circulatory and respiratory failure. Autopsy showed liver fibrosis and renal abnormalities. Neuropathological abnormalities were mainly confined to the cerebellum. Histological and immunocytochemical examination of cerebellar tissue showed partial atrophy of cerebellar folia with severe loss of Purkinje cells, granular cell depletion and various morphological changes in the remaining Purkinje cells and their dendritic arborization. Autopsy findings confirm the complexity of the CDG-Ia syndrome, and indicate that CDG-Ia is a distinct disease entity, which can be differentiated from other neurological disorders and other types of CDG, not only clinically, but also based on unique pathological findings. The data proved useful in determining the underlying disease process associated with a defective N-glycosylation pathway.
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Affiliation(s)
- E Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ , Amsterdam, The Netherlands,
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30
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Qasba PK, Ramakrishnan B, Boeggeman E. Substrate-induced conformational changes in glycosyltransferases. Trends Biochem Sci 2005; 30:53-62. [PMID: 15653326 DOI: 10.1016/j.tibs.2004.11.005] [Citation(s) in RCA: 185] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oligosaccharide chains of glycoproteins, glycolipids and glycosaminoglycans are synthesized by glycosyltransferases by the transfer of specific glycosyl moieties from activated sugar-nucleotide donors to specific acceptors. Structural studies on several of these enzymes have shown that one or two flexible loops at the substrate-binding site of the enzymes undergo a marked conformational change from an open to a closed conformation on binding the donor substrate. This conformational change, in which the loop acts as a lid covering the bound donor substrate, creates an acceptor-binding site. After the glycosyl unit is transferred from the donor to the acceptor, the saccharide product is ejected and the loop reverts to its native conformation, thereby releasing the remaining nucleotide moiety. The specificity of the sugar donor is determined by a few residues in the sugar-nucleotide-binding pocket of the enzyme that are conserved among the family members from different species.
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Affiliation(s)
- Pradman K Qasba
- Structural Glycobiology Section, Laboratory of Experimental and Computational Biology, CCR, NCI-Frederick, MD 21702, USA.
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Schachter H, Vajsar J, Zhang W. The role of defective glycosylation in congenital muscular dystrophy. Glycoconj J 2005; 20:291-300. [PMID: 15229394 DOI: 10.1023/b:glyc.0000033626.65127.e4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The dystrophin glycoprotein complex (DGC) is an assembly of proteins spanning the sarcolemma of skeletal muscle cells. Defects in the DGC appear to play critical roles in several muscular dystrophies due to disruption of basement membrane organization. O -mannosyl oligosaccharides on alpha-dystroglycan, a major extracellular component of the DGC, are essential for normal binding of alpha-dystroglycan to ligands (such as laminin) in the extracellular matrix and subsequent signal transmission to actin in the cytoskeleton of the muscle cell. Muscle-Eye-Brain disease (MEB) and Walker-Warburg Syndrome (WWS) have mutations in genes encoding glycosyltransferases needed for O -mannosyl oligosaccharide synthesis. Myodystrophic myd mice and humans with Fukuyama Congenital Muscular Dystrophy (FCMD), congenital muscular dystrophy due to defective fukutin-related protein (FKRP) and MDC1D have mutations in putative glycosyltransferases. These human congenital muscular dystrophies and the myd mouse are associated with defective glycosylation of alpha-dystroglycan. It is expected other congenital muscular dystrophies will prove to have mutations in genes involved in glycosylation.
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Affiliation(s)
- Harry Schachter
- Department of Structural Biology and Biochemistry, The Hospital for Sick Children, 555 University Avenue, Toronto, Ont. M5G 1X8, Canada.
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32
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Nozaki H, Wijayagunawardane MPB, Kodituwakku SP, Yoshida T, Nakamura T, Arai I, Urashima T, Miyamoto A. N-acetylglucosaminyltransferase I activity of bovine oviduct epithelial cells: stimulation by luteinizing hormone, vascular endothelial growth factor and tumor necrosis factor alpha. J Reprod Dev 2005; 51:229-34. [PMID: 15699581 DOI: 10.1262/jrd.16083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
N-acetylglucosaminyltransferase I (GnT I; EC 2.4.1.101), which catalyzes the first step in the conversion of oligomannose to complex or hybrid N-glycans of glycoproteins, was found in media cultured with bovine oviduct epithelial cells (BOEC) obtained from non-pregnant cows during the follicular phase. Combined treatment with specific hormones increased GnT I release from BOEC. Luteinizing hormone (LH; 10 ng/ml) alone slightly, but together with 17beta-estradiol (E2; 1 ng/ml), synergistically increased GnT I activity. Vascular endothelial growth factor (VEGF) and tumor necrosis factor (TNF) alpha, which have been shown to have their highest activities in the bovine oviduct during the periovulatory period, also increased in GnT I activity. This study provides the first evidence of an increase of GnT I release from BOEC in vitro, and shows that endocrine as well as local factors such as LH, VEGF and TNFalpha increase this activity. The results suggest that GnT I activity in the bovine oviduct may contribute to the induction of glycosylation and thereby contributing to the provision of the optimal microenvironment for fertilization and early development of the embryos.
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Affiliation(s)
- Hirofumi Nozaki
- Department of Agricultural and Life Science, Obihiro University of Agriculture and Veterinary Medicine, Japan
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Cardinale A, Filesi I, Vetrugno V, Pocchiari M, Sy MS, Biocca S. Trapping Prion Protein in the Endoplasmic Reticulum Impairs PrPC Maturation and Prevents PrPSc Accumulation. J Biol Chem 2005; 280:685-94. [PMID: 15513919 DOI: 10.1074/jbc.m407360200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The conversion of the normal cellular prion protein (PrP(C)) into the abnormal scrapie isoform (PrP(Sc)) is a key feature of prion diseases. The pathogenic mechanisms and the subcellular sites of the conversion are complex and not completely understood. In particular, little is known on the role of the early compartment of the secretory pathway in the processing of PrP(C) and in the pathogenesis of prion diseases. In order to interfere with the intracellular traffic of endogenous PrP(C) we have generated two anti-prion single chain antibody fragments (scFv) directed against different epitopes, each fragment tagged either with a secretory leader or with the ER retention signal KDEL. The stable expression of these constructs in PC12 cells allowed us to study their specific effects on the synthesis, maturation, and processing of endogenous PrP(C) and on PrP(Sc) formation. We found that ER-targeted anti-prion scFvs retain PrP(C) in the ER and inhibit its translocation to the cell surface. Retention in the ER strongly affects the maturation and glycosylation state of PrP(C), with the appearance of a new aberrant endo-H sensitive glycosylated species. Interestingly, ER-trapped PrP(C) acquires detergent insolubility and proteinase K resistance. Furthermore, we show that ER-targeted anti-prion antibodies prevent PrP(Sc) accumulation in nerve growth factor-differentiated PC12 cells, providing a new tool to study the molecular pathology of prion diseases.
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Affiliation(s)
- Alessio Cardinale
- Department of Neuroscience, University of Tor Vergata, Via Montpellier 1, 00133 Roma, Italy
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Fan X, She YM, Bagshaw RD, Callahan JW, Schachter H, Mahuran DJ. A method for proteomic identification of membrane-bound proteins containing Asn-linked oligosaccharides. Anal Biochem 2004; 332:178-86. [PMID: 15301963 DOI: 10.1016/j.ab.2004.05.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Indexed: 10/26/2022]
Abstract
Glycosylated proteins on the cell surface have been shown to be essential for cell-cell interactions in development and differentiation. Our ultimate goal is to identify Asn-linked oligosaccharides that are directly involved in these critical in vivo functions. Because such oligosaccharides would be expected to reside on the integral plasma membrane proteins, and conventional two-dimensional gel techniques are ineffective at separating such proteins, we have developed a new approach to their identification on a proteomics scale from Caenorhabditis elegans. Membrane proteins are solubilized in guanidine-HCl, precipitated, and digested with trypsin. The glycopeptides are then separated by lectin chromatography. Next, glycopeptidase F digestion removes the oligosaccharides from the peptides and converts to Asp each Asn to which one was attached. The peptides are then analyzed by matrix-assisted laser desorption/ionization quadrupole time-of-flight (MALDI-Q-TOF) mass spectrometry. Thus, the membrane glycoproteins are identified through the sequence tags of these peptides and the conversion of at least one deduced Asn residue to Asp at the Asn-X-Ser/Thr consensus sequence. To validate the utility of this approach, we have identified 13 membrane-bound N-glycosylated proteins from the major peaks observed on MALDI-Q-TOF analysis of our total glycopeptide fraction.
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Affiliation(s)
- Xiaolian Fan
- Research Institute of the Hospital for Sick Children, Toronto, Ont., Canada M5G 1X8
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35
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Tsitilou SG, Grammenoudi S. Evidence for alternative splicing and developmental regulation of the Drosophila melanogaster Mgat2 (N-acetylglucosaminyltransferase II) gene. Biochem Biophys Res Commun 2004; 312:1372-6. [PMID: 14652025 DOI: 10.1016/j.bbrc.2003.11.059] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a molecular study of the Drosophila melanogaster Mgat2 gene that codes for the N-acetylglucosaminyltransferase II. Isolation and analysis of two cDNA clones indicated that the gene is alternatively spliced, generating two transcripts of 3.3 and 2.7kb. Developmental specificity was observed between the two alternative transcripts during the major developmental stages of D. melanogaster. The deduced amino acid sequences of the two proteins show significant homology to the equivalent mammalian proteins, especially in the carboxyterminal region. In situ hybridizations in embryos and embryonic imaginal discs showed that the gene is expressed mainly but not exclusively in the brain.
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Affiliation(s)
- Sonia G Tsitilou
- Department of Biochemistry and Molecular Biology, University of Athens, 15701, Athens, Greece.
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Dupré T, Lavieu G, Moore S, Seta N. Les anomalies congénitales de glycosylation des N-glycosylprotéines. Med Sci (Paris) 2004; 20:331-8. [PMID: 15067579 DOI: 10.1051/medsci/2004203331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Protein N-glycosylation is a widely occurring and vital posttranslational modification in mammalian cells. Although the molecular machinery that is involved in the biosynthesis of these glycoconjugates has been largely identified, the recent discovery of a family of rare inborn diseases in which glycoproteins are abnormally glycosylated has both changed some of our ideas concerning glycoprotein biosynthesis, and given us new insights into this complex process. Advances in the diagnosis of the congenital disorders of glycosylation are well under way and mutations in several of the genes involved in the biosynthesis and maturation of N-linked glycans have been shown to underlie these diseases. By contrast, the chain of events that lead from faulty protein glycosylation to the often severe clinical presentation is an as yet unexplored aspect of these metabolic disorders, and represents a challenge for the future.
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Affiliation(s)
- Thierry Dupré
- Service de Biochimie A, Hôpital Bichat, AP-HP, 16, rue Henri Huchard, 75877 Paris Cedex 18, France
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Damen G, de Klerk H, Huijmans J, den Hollander J, Sinaasappel M. Gastrointestinal and other clinical manifestations in 17 children with congenital disorders of glycosylation type Ia, Ib, and Ic. J Pediatr Gastroenterol Nutr 2004; 38:282-7. [PMID: 15076627 DOI: 10.1097/00005176-200403000-00010] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVES The typical signs and symptoms of congenital disorders of glycosylation (CDG) include dysmorphy, failure to thrive, and neurologic abnormalities. However, more and more children diagnosed at a young age are not dysmorphic and do not have neurologic involvement. The authors studied the gastrointestinal and other clinical manifestations of CDG type Ia, Ib, and Ic. METHODS As of January 2003, 17 children were identified with CDG at the authors' institution. The medical records of the patients were reviewed. RESULTS Five children had CDG Ia, three children CDG Ib, and nine children CDG Ic. Age at diagnosis ranged from 2 months to 15 years. Failure to thrive was present in 80% of patients with CDG Ia, in 66% of those with CDG Ib, and in 11% of those with CDG Ic. Five children had protein-losing enteropathy (two CDG Ia, two CDG Ib, and one CDG Ic). Hepatomegaly was present in 40% of patients with CDG Ia, in 66% of those with CDG Ib, and in 11% of those with CDG Ic. In CDG Ic, hepatomegaly was transient. In CDG Ia, histologic analysis of the liver showed swollen hepatocytes, steatosis, and fibrosis. In CDG Ib, hamartomatous collections of bile ducts were seen. In one patient with CDG Ib, the clinical picture was restricted to congenital hepatic fibrosis for more than a decade. CONCLUSIONS The study confirms the heterogeneity of the clinical picture in children with CDG type Ia, Ib, and Ic. Children with protein-losing enteropathy should be tested for CDG. Protein-losing enteropathy can be caused, not only by CDG Ia and Ib, but also by type Ic. Children with congenital hepatic fibrosis should be tested for CDG, even in the absence of other symptoms. In CDG Ib, histologic analysis of the liver showed hamartomatous collections of bile ducts (Meyenburg complex).
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Affiliation(s)
- Gerard Damen
- Department of Pediatric Gastroenterology, Erasmus MC/Sophia Children Hospital, Rotterdam, the Netherlands.
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Nozaki H, Miyamoto A, Hayashi KG, Matsui M, Yoshida T, Nakamura T, Arai I, Urashima T. N-Acetylglucosaminyltransferase I Activity in Bovine Ovarian Follicular Fluids from Dominant and Atretic Follicles. J Appl Glycosci (1999) 2004. [DOI: 10.5458/jag.51.315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Vilaseca MA, Artuch R, Briones P. Defectos congénitos de la glucosilación: últimos avances y experiencia española. Med Clin (Barc) 2004; 122:707-16. [PMID: 15171833 DOI: 10.1016/s0025-7753(04)74362-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Congenital disorders of glycosylation (CDG) are a group of inherited disorders caused by defects in the synthesis and processing of the linked glycans of glycoproteins and other molecules. The first patients with CDG were described in 1980. Fifteen years later, phosphomannomutase was found to be the basis of the most frequent type: CDG-Ia. Over the last years, several novel types have been identified related to the N-glycosylation pathway, affecting enzymes or transporters of the cytosol, endoplasmic reticulum or the Golgi compartment. CDGs are multisystemic disorders, mainly affecting the central nervous system. Yet CDG-Ib and Ih are mainly hepato-intestinal diseases. Recently, several defects involving the O-glycosylation pathways have been described, indicating that some congenital muscular dystrophies and neuronal migration disorders are caused by congenital disorders of glycosylation.
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Affiliation(s)
- María Antonia Vilaseca
- Servei de Bioquímica, Hospital Sant Joan de Déu, Passeig Sant Joan de Déu 2, 08950 Esplugues de Llobregat, Barcelona, Spain.
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Butler M, Quelhas D, Critchley AJ, Carchon H, Hebestreit HF, Hibbert RG, Vilarinho L, Teles E, Matthijs G, Schollen E, Argibay P, Harvey DJ, Dwek RA, Jaeken J, Rudd PM. Detailed glycan analysis of serum glycoproteins of patients with congenital disorders of glycosylation indicates the specific defective glycan processing step and provides an insight into pathogenesis. Glycobiology 2003; 13:601-22. [PMID: 12773475 DOI: 10.1093/glycob/cwg079] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The fundamental importance of correct protein glycosylation is abundantly clear in a group of diseases known as congenital disorders of glycosylation (CDGs). In these diseases, many biological functions are compromised, giving rise to a wide range of severe clinical conditions. By performing detailed analyses of the total serum glycoproteins as well as isolated transferrin and IgG, we have directly correlated aberrant glycosylation with a faulty glycosylation processing step. In one patient the complete absence of complex type sugars was consistent with ablation of GlcNAcTase II activity. In another CDG type II patient, the identification of specific hybrid sugars suggested that the defective processing step was cell type-specific and involved the mannosidase III pathway. In each case, complementary serum proteome analyses revealed significant changes in some 31 glycoproteins, including components of the complement system. This biochemical approach to charting diseases that involve alterations in glycan processing provides a rapid indicator of the nature, severity, and cell type specificity of the suboptimal glycan processing steps; allows links to genetic mutations; indicates the expression levels of proteins; and gives insight into the pathways affected in the disease process.
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Affiliation(s)
- Michael Butler
- The Glycobiology Institute, Department of Biochemistry, Oxford University, South Parks Road, Oxford, OX1 3QU, UK
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McKillop AM, Meade A, Flatt PR, O'Harte FPM. Evaluation of the site(s) of glycation in human proinsulin by ion-trap LCQ electrospray ionization mass spectrometry. REGULATORY PEPTIDES 2003; 113:1-8. [PMID: 12686455 DOI: 10.1016/s0167-0115(02)00292-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The glycation of beta cell proteins is known to occur under hyperglycemic states. The site(s) of glycation in human proinsulin was investigated following exposure to a hyperglycemic environment under reducing conditions in vitro. Proinsulin and glycated proinsulin were separated by reversed-phase high-performance liquid chromatography (RP-HPLC) and identified using LCQ ion-trap electrospray ionization mass spectrometry. This revealed a major peak (>70% total) of monoglycated proinsulin (M(r) 9552.2 Da), a second peak (approximately 27%) of nonglycated proinsulin (M(r) 9389.8 Da), and a third minor peptide peak (approximately 3%) corresponding to diglycated proinsulin (M(r) 9717.9 Da). Following reduction of disulphide bridges with dithiothreitol, intact peptides were incubated with endoproteinase Glu-C to release nine daughter fragments for LC-MS analysis. This strategy revealed an N-terminal fragment of monoglycated proinsulin Phe(1)-Glu(13), which contained a single glucitol adduct (M(r) 1642.0 Da). A similar treatment of small amounts of purified diglycated proinsulin revealed a fragment with Phe(1)-Glu(13) linked by a disulphide bridge to Gln(70)-Glu(82) containing two glucitol adducts (M(r) 3292.7 Da). In summary, these studies indicate that the major site of glycation in proinsulin, like insulin, is the amino terminal Phe(1) residue. However, small amounts of diglycated proinsulin occur naturally, involving an additional site of glycation located between Gln(70) and Glu(82).
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Affiliation(s)
- Aine M McKillop
- School of Biomedical Sciences, University of Ulster, Northern Ireland BT52 1SA, Coleraine, UK.
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42
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Chantret I, Dancourt J, Dupré T, Delenda C, Bucher S, Vuillaumier-Barrot S, Ogier de Baulny H, Peletan C, Danos O, Seta N, Durand G, Oriol R, Codogno P, Moore SEH. A deficiency in dolichyl-P-glucose:Glc1Man9GlcNAc2-PP-dolichyl alpha3-glucosyltransferase defines a new subtype of congenital disorders of glycosylation. J Biol Chem 2003; 278:9962-71. [PMID: 12480927 DOI: 10.1074/jbc.m211950200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The underlying causes of type I congenital disorders of glycosylation (CDG I) have been shown to be mutations in genes encoding proteins involved in the biosynthesis of the dolichyl-linked oligosaccharide (Glc(3)Man(9)GlcNAc(2)-PP-dolichyl) that is required for protein glycosylation. Here we describe a CDG I patient displaying gastrointestinal problems but no central nervous system deficits. Fibroblasts from this patient accumulate mainly Man(9)GlcNAc(2)-PP-dolichyl, but in the presence of castanospermine, an endoplasmic reticulum glucosidase inhibitor Glc(1)Man(9)GlcNAc(2)-PP-dolichyl predominates, suggesting inefficient addition of the second glucose residue onto lipid-linked oligosaccharide. Northern blot analysis revealed the cells from the patient to possess only 10-20% normal amounts of mRNA encoding the enzyme, dolichyl-P-glucose:Glc(1)Man(9)GlcNAc(2)-PP-dolichyl alpha3-glucosyltransferase (hALG8p), which catalyzes this reaction. Sequencing of hALG8 genomic DNA revealed exon 4 to contain a base deletion in one allele and a base insertion in the other. Both mutations give rise to premature stop codons predicted to generate severely truncated proteins, but because the translation inhibitor emetine was shown to stabilize the hALG8 mRNA from the patient to normal levels, it is likely that both transcripts undergo nonsense-mediated mRNA decay. As the cells from the patient were successfully complemented with wild type hALG8 cDNA, we conclude that these mutations are the underlying cause of this new CDG I subtype that we propose be called CDG Ih.
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MESH Headings
- Alleles
- Amino Acid Sequence
- Base Sequence
- Blotting, Northern
- Blotting, Western
- Carbohydrate Metabolism, Inborn Errors/diagnosis
- Carbohydrate Metabolism, Inborn Errors/enzymology
- Carbohydrate Metabolism, Inborn Errors/genetics
- Cells, Cultured
- Chloroform/pharmacology
- Chromatography, Thin Layer
- Codon, Terminator
- DNA Mutational Analysis
- DNA, Complementary/metabolism
- Fibroblasts/metabolism
- Glucosyltransferases/chemistry
- Glucosyltransferases/metabolism
- Glycosylation
- Humans
- Lipids/chemistry
- Lymphocytes/metabolism
- Molecular Sequence Data
- Mutation
- Oligosaccharides/chemistry
- RNA, Messenger/metabolism
- Signal Transduction
- Time Factors
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Affiliation(s)
- Isabelle Chantret
- Unité de Glycobiologie et Signalisation Cellulaire, INSERM, U504, Bâtiment INSERM, 16 Avenue Paul Vaillant-Couturier, 94807 Villejuif, France
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Miller BS, Freeze HH. New disorders in carbohydrate metabolism: congenital disorders of glycosylation and their impact on the endocrine system. Rev Endocr Metab Disord 2003; 4:103-13. [PMID: 12618564 DOI: 10.1023/a:1021883605280] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Bradley S Miller
- Division of Pediatric Endocrinology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, USA
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Chen S, Spence AM, Schachter H. Isolation of null alleles of the Caenorhabditis elegans gly-12, gly-13 and gly-14 genes, all of which encode UDP-GlcNAc: alpha-3-D-mannoside beta1,2-N-acetylglucosaminyltransferase I activity. Biochimie 2003; 85:391-401. [PMID: 12770777 DOI: 10.1016/s0300-9084(03)00009-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
UDP-GlcNAc: alpha-3-D-mannoside beta1,2-N-acetylglucosaminyltransferase I (GnT I) is a Golgi-resident enzyme which transfers a GlcNAc residue in beta1,2 linkage to the Manalpha1,3Manbeta-terminus of (Manalpha1,6(Manalpha1,3)Manalpha1,6)(Manalpha1,3)Manbeta1,4GlcNAcbeta1,4GlcNAc-Asn-protein, thereby initiating the synthesis of hybrid N-glycans. Three Caenorhabditis elegans genes homologous to mammalian GnT I (designated gly-12, gly-13 and gly-14) have been cloned. All three cDNAs encode proteins with GnT I enzyme activity. We report in this paper the preparation by ultra-violet (UV) light irradiation in the presence of trimethylpsoralen, of mutants lacking either gly-12, gly-13 or gly-14. A double null mutation in the gly-12 and gly-14 genes (gly-14; gly-12) has also been prepared. These mutations are intragene deletions, removing large portions of the GnT I catalytic domain, and are therefore, all molecular nulls. The gly-12 and gly-14 mutants as well as the gly-14; gly-12 double mutant all displayed wild-type phenotypes, indicating that neither gly-12 nor gly-14 is necessary for worm development under standard laboratory conditions. In contrast, about 60% of the mutants lacking the gly-13 gene arrested as L1 larvae at 20 degrees C and the remaining 40% homozygous worms grew to adulthood but displayed severe morphological and behavioral defects despite the presence of the other two GnT I genes, gly-12 and gly-14. Attempts to rescue the gly-13 null phenotype with the wild type transgene were not successful. However, lethality co-segregated with the gly-13 deletion within 0.02 map units (mu) in genetic mapping experiments, suggesting that the gly-13 mutation is responsible for the phenotype.
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Affiliation(s)
- Shihao Chen
- The Burnham Institute, La Jolla, CA 92037, USA
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Pathways and functions of mammalian protein glycosylation. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0167-7306(03)38026-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
Congenital disorders of glycosylation (CDGs) are due to defects in the synthesis of the glycan moiety of glycoproteins or other glycoconjugates. This review is devoted mainly to the clinical aspects of protein glycosylation defects. There are two main types of protein glycosylation: N-glycosylation and O-glycosylation. N-glycosylation generally consists of an assembly pathway (in cytosol and endoplasmic reticulum) and a processing pathway (in endoplasmic reticulum and Golgi). O-glycosylation lacks a processing pathway but is otherwise more complex. Sixteen disease-causing defects are known in protein glycosylation: 12 in N-glycosylation and four in O-glycosylation. The N-glycosylation defects comprise eight assembly defects (CDG-I) designated CDG-Ia to CDG-Ih, and four processing defects (CDG-II) designated CDG-IIa to CDG-IId. By far the most frequent is CDG-Ia (phosphomannomutase-2 deficiency). It affects the nervous system and many other organs. Its clinical expression varies from extremely severe to very mild (and thus probably underdiagnosed). The most interesting disease in this group is CDG-Ib (phosphomannose isomerase deficiency) because it is so far the only efficiently treatable CDG (mannose treatment). It has a hepatic-intestinal presentation. The O-glycosylation defects comprise two O-xylosylglycan defects (a progeroid variant of Ehlers-Danlos syndrome and the multiple exostoses syndrome) and two O-mannosylglycan defects (Walker-Warburg syndrome and muscle-eye-brain disease). All known CDGs have a recessive inheritance except for multiple exostoses syndrome, which is dominantly inherited. There is a rapidly growing group of putative CDGs with a large spectrum of clinical presentations (CDG-x). Serum transferrin iso-electrofocusing remains the cornerstone of the screening for N-glycosylation defects associated with sialic acid deficiency. Abnormal patterns can be grouped in to type 1 and type 2. However, a normal pattern does not exclude these defects. Screening for the other CDGs is much more difficult, particularly when the defect is organ- or system-restricted. The latter group promises to become an important new chapter in CDG. It is concluded that CDGs will eventually cover the whole clinical spectrum of paediatric and adult disease manifestations.
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Affiliation(s)
- J Jaeken
- Department of Pediatrics, Centre for Metabolic Disease, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.
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Li Y, Ogata Y, Freeze HH, Scott CR, Turecek F, Gelb MH. Affinity capture and elution/electrospray ionization mass spectrometry assay of phosphomannomutase and phosphomannose isomerase for the multiplex analysis of congenital disorders of glycosylation types Ia and Ib. Anal Chem 2003; 75:42-8. [PMID: 12530817 DOI: 10.1021/ac0205053] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report a new application of affinity capture-elution electrospray mass spectrometry (ACESI-MS) to assay the enzymes phosphomannomutase (PMM) and phosphomannose isomerase (PMI), which when deficient cause congenital disorders of glycosylation CDG-type Ia and type Ib, respectively. The novel feature of this mass-spectrometry-based assay is that it allows one to distinguish and quantify enzymatic products that are isomeric with their substrates that are present simultaneously in complex mixtures, such as cultured human cell homogenates. This is achieved by coupled assays in which the PMM and PMI primary products are in vitro subjected to another enzymatic reaction with yeast transketolase that changes the mass of the products to be detected by mass spectrometry. The affinity purification procedure is fully automated, and the mass spectrometric analysis is multiplexed in a fashion that is suitable for high-throughput applications.
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Affiliation(s)
- Yijun Li
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
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Abstract
Genes that cause human disorders in N-linked oligosaccharide biosynthesis have appeared much faster than animal model systems to study them. In most models, a single gene is altered or deleted while other genes and the environment are held constant. Since humans have variable genetic backgrounds and environments, model systems may only partially mimic the actual disorders. Mutations in seven of the 30-40 genes needed for the synthesis and transfer of oligosaccharides from the lipid donor to the nascent protein acceptors in the endoplasmic reticulum cause Type I Congenital Disorders of Glycosylation (CDG). Since all of these gene products ultimately contribute to the same final step, one might suspect that all the diseases would be very similar. However, even patients with mutations in the same gene show considerable phenotypic variability. Modifier, or susceptibility genes in the background likely explain some variations of the "primary" gene chosen for study. Add to this the stress of infections, dietary insufficiencies, and the demands of growth itself. These issues are particularly important during development when the temporal and spatial specific interplay of cell adhesions and signals has only a single opportunity. Multiple hypomorphic alleles of genes in the same pathway may have synergistic effects. Investigators designing model systems to study human glycosylation disorders may want to construct strains with several heterozygous hypomorphic alleles in rate-limiting steps in the glycosylation pathway.
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Affiliation(s)
- Hudson H Freeze
- Glycobiology and Carbohydrate Chemistry Program, The Burnham Institute, La Jolla, CA 92037, USA.
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Moremen KW. Golgi alpha-mannosidase II deficiency in vertebrate systems: implications for asparagine-linked oligosaccharide processing in mammals. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1573:225-35. [PMID: 12417404 DOI: 10.1016/s0304-4165(02)00388-4] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The maturation of N-glycans to complex type structures on cellular and secreted proteins is essential for the roles that these structures play in cell adhesion and recognition events in metazoan organisms. Critical steps in the biosynthetic pathway leading from high mannose to complex structures include the trimming of mannose residues by processing mannosidases in the endoplasmic reticulum (ER) and Golgi complex. These exo-mannosidases comprise two separate families of enzymes that are distinguished by enzymatic characteristics and sequence similarity. Members of the Class 2 mannosidase family (glycosylhydrolase family 38) include enzymes involved in trimming reactions in N-glycan maturation in the Golgi complex (Golgi mannosidase II) as well as catabolic enzymes in lysosomes and cytosol. Studies on the biological roles of complex type N-glycans have employed a variety of strategies including the treatment of cells with glycosidase inhibitors, characterization of human patients with enzymatic defects in processing enzymes, and generation of mouse models for the enzyme deficiency by selective gene disruption approaches. Corresponding studies on Golgi mannosidase II have employed swainsonine, an alkaloid natural plant product that causes "locoism", a phenocopy of the lysosomal storage disease, alpha-mannosidosis, as a result of the additional targeting of the broad-specificity lysosomal mannosidase by this compound. The human deficiency in Golgi mannosidase II is characterized by congenital dyserythropoietic anemia with splenomegaly and various additional abnormalities and complications. Mouse models for Golgi mannosidase II deficiency recapitulate many of the pathological features of the human disease and confirm that the unexpectedly mild effects of the enzyme deficiency result from a tissue-specific and glycoprotein substrate-specific alternate pathway for synthesis of complex N-glycans. In addition, the mutant mice develop symptoms of a systemic autoimmune disorder as a consequence of the altered glycosylation. This review will discuss the biochemical features of Golgi mannosidase II and the consequences of its deficiency in mammalian systems as a model for the effects of alterations in vertebrate N-glycan maturation during development.
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Affiliation(s)
- Kelley W Moremen
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA.
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Chen S, Tan J, Reinhold VN, Spence AM, Schachter H. UDP-N-acetylglucosamine:alpha-3-D-mannoside beta-1,2-N-acetylglucosaminyltransferase I and UDP-N-acetylglucosamine:alpha-6-D-mannoside beta-1,2-N-acetylglucosaminyltransferase II in Caenorhabditis elegans. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1573:271-9. [PMID: 12417409 DOI: 10.1016/s0304-4165(02)00393-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
UDP-N-acetylglucosamine:alpha-3-D-mannoside beta-1,2-N-acetylglucosaminyltransferase I (GnT I) and UDP-N-acetylglucosamine:alpha-6-D-mannoside beta-1,2-N-acetylglucosaminyltransferase II (GnT II) are key enzymes in the synthesis of Asn-linked hybrid and complex glycans. We have cloned cDNAs from Caenorhabditis elegans for three genes homologous to mammalian GnT I (designated gly-12, gly-13 and gly-14) and one gene homologous to mammalian GnT II. All four cDNAs encode proteins which have the domain structure typical of previously cloned Golgi-type glycosyltransferases and show enzymatic activity (GnT I and GnT II, respectively) on expression in transgenic worms. We have isolated worm mutants lacking the three GnT I genes by the method of ultraviolet irradiation in the presence of trimethylpsoralen (TMP); null mutants for GnT II have not yet been obtained. The gly-12 and gly-14 mutants as well as the gly-14;gly-12 double mutant displayed wild-type phenotypes indicating that neither gly-12 nor gly-14 is necessary for worm development under standard laboratory conditions. This finding and other data indicate that the GLY-13 protein is the major functional GnT I in C. elegans. The mutation lacking the gly-13 gene is partially lethal and the few survivors display severe morphological and behavioral defects. We have shown that the observed phenotype co-segregates with the gly-13 deletion in genetic mapping experiments although a second mutation near the gly-13 gene cannot as yet be ruled out. Our data indicate that complex and hybrid N-glycans may play critical roles in the morphogenesis of C. elegans, as they have been shown to do in mice and men.
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Affiliation(s)
- Shihao Chen
- Department of Structural Biology and Biochemistry, The Hospital for Sick Children, Toronto, ON, Canada
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