1
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Sneed SL, Reese BB, Laureano AF, Ratnapriya S, Fraschilla I, Jeffrey KL, Coffey GP, Conley PB, Anthony RM. An engineered immunomodulatory IgG1 Fc suppresses autoimmune inflammation through pathways shared with i.v. immunoglobulin. J Clin Invest 2024; 134:e172980. [PMID: 38357917 PMCID: PMC10866649 DOI: 10.1172/jci172980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 12/27/2023] [Indexed: 02/16/2024] Open
Abstract
Immunoglobulin G (IgG) antibodies in the form of high-dose intravenous immunoglobulin (IVIG) exert immunomodulatory activity and are used in this capacity to treat inflammatory and autoimmune diseases. Reductionist approaches have revealed that terminal sialylation of the single asparagine-linked (N-linked) glycan at position 297 of the IgG1 Fc bestows antiinflammatory activity, which can be recapitulated by introduction of an F241A point mutation in the IgG1 Fc (FcF241A). Here, we examined the antiinflammatory activity of CHO-K1 cell-produced FcF241A in vivo in models of autoimmune inflammation and found it to be independent of sialylation. Intriguingly, sialylation markedly improved the half-life and bioavailability of FcF241A via impaired interaction with the asialoglycoprotein receptor ASGPR. Further, FcF241A suppressed inflammation through the same molecular pathways as IVIG and sialylated IgG1 Fc and required the C-type lectin SIGN-R1 in vivo. This contrasted with FcAbdeg (efgartigimod), an engineered IgG1 Fc with enhanced neonatal Fc receptor (FcRn) binding, which reduced total serum IgG concentrations, independent of SIGN-R1. When coadministered, FcF241A and FcAbdeg exhibited combinatorial antiinflammatory activity. Together, these results demonstrated that the antiinflammatory activity of FcF241A requires SIGN-R1, similarly to that of high-dose IVIG and sialylated IgG1, and can be used in combination with other antiinflammatory therapeutics that rely on divergent pathways, including FcAbdeg.
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Affiliation(s)
- Sunny L. Sneed
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Harvard Medical School, and
| | - Brian B. Reese
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Harvard Medical School, and
| | - Ana F.S. Laureano
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Harvard Medical School, and
| | - Sneha Ratnapriya
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Harvard Medical School, and
| | - Isabella Fraschilla
- Center for the Study of Inflammatory Bowel Disease, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Kate L. Jeffrey
- Center for the Study of Inflammatory Bowel Disease, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | | | | | - Robert M. Anthony
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Harvard Medical School, and
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2
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Vos GM, Hooijschuur KC, Li Z, Fjeldsted J, Klein C, de Vries RP, Toraño JS, Boons GJ. Sialic acid O-acetylation patterns and glycosidic linkage type determination by ion mobility-mass spectrometry. Nat Commun 2023; 14:6795. [PMID: 37880209 PMCID: PMC10600165 DOI: 10.1038/s41467-023-42575-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 10/16/2023] [Indexed: 10/27/2023] Open
Abstract
O-acetylation is a common modification of sialic acids that has been implicated in a multitude of biological and disease processes. A lack of analytical methods that can determine exact structures of sialic acid variants is a hurdle to determine roles of distinct O-acetylated sialosides. Here, we describe a drift tube ion mobility-mass spectrometry approach that can elucidate exact O-acetylation patterns as well as glycosidic linkage types of sialosides isolated from complex biological samples. It is based on the use of a library of synthetic O-acetylated sialosides to establish intrinsic collision cross section (CCS) values of diagnostic fragment ions. The CCS values were used to characterize O-acetylated sialosides from mucins and N-linked glycans from biologicals as well as equine tracheal and nasal tissues. It uncovered contrasting sialic acid linkage types of acetylated and non-acetylated sialic acids and provided a rationale for sialic acid binding preferences of equine H7 influenza A viruses.
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Affiliation(s)
- Gaёl M Vos
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Kevin C Hooijschuur
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Zeshi Li
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | | | | | - Robert P de Vries
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Javier Sastre Toraño
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands.
| | - Geert-Jan Boons
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands.
- Bijvoet Center for Biomolecular Research, Utrecht University, 3584 CG, Utrecht, The Netherlands.
- Complex Carbohydrate Research Center and Department of Chemistry, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA.
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3
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Herrera-Marcos LV, Sahali D, Ollero M. 9-O Acetylated Gangliosides in Health and Disease. Biomolecules 2023; 13:biom13050827. [PMID: 37238697 DOI: 10.3390/biom13050827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/05/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
Glycosphingolipids comprise a lipid class characterized by the presence of sugar moieties attached to a ceramide backbone. The role of glycosphingolipids in pathophysiology has gained relevance in recent years in parallel with the development of analytical technologies. Within this vast family of molecules, gangliosides modified by acetylation represent a minority. Described for the first time in the 1980s, their relation to pathologies has resulted in increased interest in their function in normal and diseased cells. This review presents the state of the art on 9-O acetylated gangliosides and their link to cellular disorders.
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Affiliation(s)
| | - Dil Sahali
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France
- AP-HP, Hôpitaux Universitaires Henri Mondor, Service de Néphrologie, F-94010 Creteil, France
| | - Mario Ollero
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France
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4
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Bose P, Jaiswal MK, Singh SK, Singh RK, Tiwari VK. Growing impact of sialic acid-containing glycans in future drug discovery. Carbohydr Res 2023; 527:108804. [PMID: 37031650 DOI: 10.1016/j.carres.2023.108804] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/21/2023] [Accepted: 03/29/2023] [Indexed: 04/05/2023]
Abstract
In nature, almost all cells are covered with a complex array of glycan chain namely sialic acids or nuraminic acids, a negatively charged nine carbon sugars which is considered for their great therapeutic importance since long back. Owing to its presence at the terminal end of lipid bilayer (commonly known as terminal sugars), the well-defined sialosides or sialoconjugates have served pivotal role on the cell surfaces and thus, the sialic acid-containing glycans can modulate and mediate a number of imperative cellular interactions. Understanding of the sialo-protein interaction and their roles in vertebrates in regard of normal physiology, pathological variance, and evolution has indeed a noteworthy journey in medicine. In this tutorial review, we present a concise overview about the structure, linkages in chemical diversity, biological significance followed by chemical and enzymatic modification/synthesis of sialic acid containing glycans. A more focus is attempted about the recent advances, opportunity, and more over growing impact of sialosides and sialoconjugates in future drug discovery and development.
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5
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Visser EA, Moons SJ, Timmermans SBPE, de Jong H, Boltje TJ, Büll C. Sialic acid O-acetylation: From biosynthesis to roles in health and disease. J Biol Chem 2021; 297:100906. [PMID: 34157283 PMCID: PMC8319020 DOI: 10.1016/j.jbc.2021.100906] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/16/2021] [Accepted: 06/18/2021] [Indexed: 02/06/2023] Open
Abstract
Sialic acids are nine-carbon sugars that frequently cap glycans at the cell surface in cells of vertebrates as well as cells of certain types of invertebrates and bacteria. The nine-carbon backbone of sialic acids can undergo extensive enzymatic modification in nature and O-acetylation at the C-4/7/8/9 position in particular is widely observed. In recent years, the detection and analysis of O-acetylated sialic acids have advanced, and sialic acid-specific O-acetyltransferases (SOATs) and O-acetylesterases (SIAEs) that add and remove O-acetyl groups, respectively, have been identified and characterized in mammalian cells, invertebrates, bacteria, and viruses. These advances now allow us to draw a more complete picture of the biosynthetic pathway of the diverse O-acetylated sialic acids to drive the generation of genetically and biochemically engineered model cell lines and organisms with altered expression of O-acetylated sialic acids for dissection of their roles in glycoprotein stability, development, and immune recognition, as well as discovery of novel functions. Furthermore, a growing number of studies associate sialic acid O-acetylation with cancer, autoimmunity, and infection, providing rationale for the development of selective probes and inhibitors of SOATs and SIAEs. Here, we discuss the current insights into the biosynthesis and biological functions of O-acetylated sialic acids and review the evidence linking this modification to disease. Furthermore, we discuss emerging strategies for the design, synthesis, and potential application of unnatural O-acetylated sialic acids and inhibitors of SOATs and SIAEs that may enable therapeutic targeting of this versatile sialic acid modification.
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Affiliation(s)
- Eline A Visser
- Institute for Molecules and Materials, Department of Synthetic Organic Chemistry, Radboud University Nijmegen, Nijmegen, the Netherlands
| | - Sam J Moons
- Institute for Molecules and Materials, Department of Synthetic Organic Chemistry, Radboud University Nijmegen, Nijmegen, the Netherlands
| | - Suzanne B P E Timmermans
- Institute for Molecules and Materials, Department of Synthetic Organic Chemistry, Radboud University Nijmegen, Nijmegen, the Netherlands
| | - Heleen de Jong
- Institute for Molecules and Materials, Department of Synthetic Organic Chemistry, Radboud University Nijmegen, Nijmegen, the Netherlands
| | - Thomas J Boltje
- Institute for Molecules and Materials, Department of Synthetic Organic Chemistry, Radboud University Nijmegen, Nijmegen, the Netherlands.
| | - Christian Büll
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; Hubrecht Institute, Utrecht, the Netherlands.
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6
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Cavdarli S, Schröter L, Albers M, Baumann AM, Vicogne D, Le Doussal JM, Mühlenhoff M, Delannoy P, Groux-Degroote S. Role of Sialyl- O-Acetyltransferase CASD1 on GD2 Ganglioside O-Acetylation in Breast Cancer Cells. Cells 2021; 10:cells10061468. [PMID: 34208013 PMCID: PMC8230688 DOI: 10.3390/cells10061468] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/01/2021] [Accepted: 05/07/2021] [Indexed: 02/08/2023] Open
Abstract
The O-acetylated form of GD2, almost exclusively expressed in cancerous tissues, is considered to be a promising therapeutic target for neuroectoderm-derived tumors, especially for breast cancer. Our recent data have shown that 9-O-acetylated GD2 (9-OAcGD2) is the major O-acetylated ganglioside species in breast cancer cells. In 2015, Baumann et al. proposed that Cas 1 domain containing 1 (CASD1), which is the only known human sialyl-O-acetyltransferase, plays a role in GD3 O-acetylation. However, the mechanisms of ganglioside O-acetylation remain poorly understood. The aim of this study was to determine the involvement of CASD1 in GD2 O-acetylation in breast cancer. The role of CASD1 in OAcGD2 synthesis was first demonstrated using wild type CHO and CHOΔCasd1 cells as cellular models. Overexpression using plasmid transfection and siRNA strategies was used to modulate CASD1 expression in SUM159PT breast cancer cell line. Our results showed that OAcGD2 expression was reduced in SUM159PT that was transiently depleted for CASD1 expression. Additionally, OAcGD2 expression was increased in SUM159PT cells transiently overexpressing CASD1. The modulation of CASD1 expression using transient transfection strategies provided interesting insights into the role of CASD1 in OAcGD2 and OAcGD3 biosynthesis, and it highlights the importance of further studies on O-acetylation mechanisms.
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Affiliation(s)
- Sumeyye Cavdarli
- Univ Lille, CNRS, UMR 8576-UGSF- Unité de Glycosylation Structurale et Fonctionnelle, 59655 Villeneuve d’Ascq, France; (S.C.); (D.V.); (P.D.)
| | - Larissa Schröter
- Institute of Clinical Biochemistry, Hannover Medical School, 30623 Hannover, Germany; (L.S.); (M.A.); (A.-M.B.); (M.M.)
| | - Malena Albers
- Institute of Clinical Biochemistry, Hannover Medical School, 30623 Hannover, Germany; (L.S.); (M.A.); (A.-M.B.); (M.M.)
| | - Anna-Maria Baumann
- Institute of Clinical Biochemistry, Hannover Medical School, 30623 Hannover, Germany; (L.S.); (M.A.); (A.-M.B.); (M.M.)
| | - Dorothée Vicogne
- Univ Lille, CNRS, UMR 8576-UGSF- Unité de Glycosylation Structurale et Fonctionnelle, 59655 Villeneuve d’Ascq, France; (S.C.); (D.V.); (P.D.)
| | | | - Martina Mühlenhoff
- Institute of Clinical Biochemistry, Hannover Medical School, 30623 Hannover, Germany; (L.S.); (M.A.); (A.-M.B.); (M.M.)
| | - Philippe Delannoy
- Univ Lille, CNRS, UMR 8576-UGSF- Unité de Glycosylation Structurale et Fonctionnelle, 59655 Villeneuve d’Ascq, France; (S.C.); (D.V.); (P.D.)
| | - Sophie Groux-Degroote
- Univ Lille, CNRS, UMR 8576-UGSF- Unité de Glycosylation Structurale et Fonctionnelle, 59655 Villeneuve d’Ascq, France; (S.C.); (D.V.); (P.D.)
- Correspondence:
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7
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Genetic glycoengineering in mammalian cells. J Biol Chem 2021; 296:100448. [PMID: 33617880 PMCID: PMC8042171 DOI: 10.1016/j.jbc.2021.100448] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 02/06/2023] Open
Abstract
Advances in nuclease-based gene-editing technologies have enabled precise, stable, and systematic genetic engineering of glycosylation capacities in mammalian cells, opening up a plethora of opportunities for studying the glycome and exploiting glycans in biomedicine. Glycoengineering using chemical, enzymatic, and genetic approaches has a long history, and precise gene editing provides a nearly unlimited playground for stable engineering of glycosylation in mammalian cells to explore and dissect the glycome and its many biological functions. Genetic engineering of glycosylation in cells also brings studies of the glycome to the single cell level and opens up wider use and integration of data in traditional omics workflows in cell biology. The last few years have seen new applications of glycoengineering in mammalian cells with perspectives for wider use in basic and applied glycosciences, and these have already led to discoveries of functions of glycans and improved designs of glycoprotein therapeutics. Here, we review the current state of the art of genetic glycoengineering in mammalian cells and highlight emerging opportunities.
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8
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Cipollo JF, Parsons LM. Glycomics and glycoproteomics of viruses: Mass spectrometry applications and insights toward structure-function relationships. MASS SPECTROMETRY REVIEWS 2020; 39:371-409. [PMID: 32350911 PMCID: PMC7318305 DOI: 10.1002/mas.21629] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 04/01/2020] [Accepted: 04/05/2020] [Indexed: 05/21/2023]
Abstract
The advancement of viral glycomics has paralleled that of the mass spectrometry glycomics toolbox. In some regard the glycoproteins studied have provided the impetus for this advancement. Viral proteins are often highly glycosylated, especially those targeted by the host immune system. Glycosylation tends to be dynamic over time as viruses propagate in host populations leading to increased number of and/or "movement" of glycosylation sites in response to the immune system and other pressures. This relationship can lead to highly glycosylated, difficult to analyze glycoproteins that challenge the capabilities of modern mass spectrometry. In this review, we briefly discuss five general areas where glycosylation is important in the viral niche and how mass spectrometry has been used to reveal key information regarding structure-function relationships between viral glycoproteins and host cells. We describe the recent past and current glycomics toolbox used in these analyses and give examples of how the requirement to analyze these complex glycoproteins has provided the incentive for some advances seen in glycomics mass spectrometry. A general overview of viral glycomics, special cases, mass spectrometry methods and work-flows, informatics and complementary chemical techniques currently used are discussed. © 2020 The Authors. Mass Spectrometry Reviews published by John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- John F. Cipollo
- Center for Biologics Evaluation and Research, Food and Drug AdministrationSilver SpringMaryland
| | - Lisa M. Parsons
- Center for Biologics Evaluation and Research, Food and Drug AdministrationSilver SpringMaryland
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9
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Otake AH, de Freitas Saito R, Duarte APM, Ramos AF, Chammas R. G D3 ganglioside-enriched extracellular vesicles stimulate melanocyte migration. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:422-432. [PMID: 29908366 DOI: 10.1016/j.bbalip.2018.06.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 05/17/2018] [Accepted: 06/12/2018] [Indexed: 01/30/2023]
Abstract
Melanomas often accumulate gangliosides, sialic acid-containing glycosphingolipids found in the outer leaflet of plasma membranes, as disialoganglioside GD3 and its derivatives. Here, we have transfected the GD3 synthase gene (ST8Sia I) in a normal melanocyte cell line in order to evaluate changes in the biological behavior of non-transformed cells. GD3-synthase expressing cells converted GM3 into GD3 and accumulated both GD3 and its acetylated form, 9-O-acetyl-GD3. Melanocytes were rendered more migratory on laminin-1 surfaces. Cell migration studies using the different transfectants, either treated or not with the glucosylceramide synthase inhibitor d-1-threo-1-phenyl-2-palmitoylamino-3-pyrrolidino-1-propanol (PPPP), allowed us to show that while GM3 is a negative regulator of melanocyte migration, GD3 increases it. We showed that gangliosides were shed to the matrix by migrating cells and that GD3 synthase transfected cells shed extracellular vesicles (EVs) enriched in GD3. EVs enriched in GD3 stimulated cell migration of GD3 negative cells, as observed in time lapse microscopy studies. Otherwise, EVs shed by GM3+veGD3-ve cells impaired migration and diminished cell velocity in cells overexpressing GD3. The balance of antimigratory GM3 and promigratory GD3 gangliosides in melanocytes could be altered not only by the overexpression of enzymes such as ST8Sia I, but also by the horizontal transfer of ganglioside enriched extracellular vesicles. This study highlights that extracellular vesicles transfer biological information also through their membrane components, which include a variety of glycosphingolipids remodeled in disease states such as cancer.
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Affiliation(s)
- Andreia Hanada Otake
- Center for Translational Research in Oncology (LIM-24), Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina, Universidade de São Paulo, 01246-000 São Paulo, SP, Brazil
| | - Renata de Freitas Saito
- Center for Translational Research in Oncology (LIM-24), Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina, Universidade de São Paulo, 01246-000 São Paulo, SP, Brazil
| | - Ana Paula Marques Duarte
- Center for Translational Research in Oncology (LIM-24), Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina, Universidade de São Paulo, 01246-000 São Paulo, SP, Brazil
| | - Alexandre Ferreira Ramos
- Center for Translational Research in Oncology (LIM-24), Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina, Universidade de São Paulo, 01246-000 São Paulo, SP, Brazil; Escola de Artes, Ciências e Humanidades da Universidade de São Paulo, São Paulo, SP, Brazil
| | - Roger Chammas
- Center for Translational Research in Oncology (LIM-24), Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina, Universidade de São Paulo, 01246-000 São Paulo, SP, Brazil.
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10
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Lertkiatmongkol P, Paddock C, Newman DK, Zhu J, Thomas MJ, Newman PJ. The Role of Sialylated Glycans in Human Platelet Endothelial Cell Adhesion Molecule 1 (PECAM-1)-mediated Trans Homophilic Interactions and Endothelial Cell Barrier Function. J Biol Chem 2016; 291:26216-26225. [PMID: 27793989 DOI: 10.1074/jbc.m116.756502] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/12/2016] [Indexed: 11/06/2022] Open
Abstract
Platelet Endothelial Cell Adhesion Molecule 1 (PECAM-1) is a major component of the endothelial cell intercellular junction. Previous studies have shown that PECAM-1 homophilic interactions, mediated by amino-terminal immunoglobulin homology domain 1, contribute to maintenance of the vascular permeability barrier and to its re-establishment following inflammatory or thrombotic insult. PECAM-1 glycans account for ∼30% of its molecular mass, and the newly solved crystal structure of human PECAM-1 immunoglobulin homology domain 1 reveals that a glycan emanating from the asparagine residue at position 25 (Asn-25) is located within the trans homophilic-binding interface, suggesting a role for an Asn-25-associated glycan in PECAM-1 homophilic interactions. In support of this possibility, unbiased molecular docking studies revealed that negatively charged α2,3 sialic acid moieties bind tightly to a groove within the PECAM-1 homophilic interface in an orientation that favors the formation of an electrostatic bridge with positively charged Lys-89, mutation of which has been shown previously to disrupt PECAM-1-mediated homophilic binding. To verify the contribution of the Asn-25 glycan to endothelial barrier function, we generated an N25Q mutant form of PECAM-1 that is not glycosylated at this position and examined its ability to contribute to vascular integrity in endothelial cell-like REN cells. Confocal microscopy showed that although N25Q PECAM-1 concentrates normally at cell-cell junctions, the ability of this mutant form of PECAM-1 to support re-establishment of a permeability barrier following disruption with thrombin was significantly compromised. Taken together, these data suggest that a sialic acid-containing glycan emanating from Asn-25 reinforces dynamic endothelial cell-cell interactions by stabilizing the PECAM-1 homophilic binding interface.
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Affiliation(s)
- Panida Lertkiatmongkol
- From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and.,the Departments of Pharmacology
| | - Cathy Paddock
- From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and
| | - Debra K Newman
- From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and.,the Departments of Pharmacology
| | - Jieqing Zhu
- From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and.,Biochemistry, and
| | | | - Peter J Newman
- From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and .,the Departments of Pharmacology.,Cell Biology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
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11
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Analytical detection and characterization of biopharmaceutical glycosylation by MS. Bioanalysis 2016; 8:711-27. [PMID: 26964748 DOI: 10.4155/bio.16.20] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Glycosylation plays an important role in ensuring the proper structure and function of most biotherapeutic proteins. Even small changes in glycan composition, structure, or location can have a drastic impact on drug safety and efficacy. Recently, glycosylation has become the subject of increased focus as biopharmaceutical companies rush to create not only biosimilars, but also biobetters based on existing biotherapeutic proteins. Against this backdrop of ongoing biopharmaceutical innovation, updated methods for accurate and detailed analysis of protein glycosylation are critical for biopharmaceutical companies and government regulatory agencies alike. This review summarizes current methods of characterizing biopharmaceutical glycosylation, including compositional mass profiling, isomer-specific profiling and structural elucidation by MS and hyphenated techniques.
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12
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Liu R, Giddens J, McClung CM, Magnelli PE, Wang LX, Guthrie EP. Evaluation of a glycoengineered monoclonal antibody via LC-MS analysis in combination with multiple enzymatic digestion. MAbs 2015; 8:340-6. [PMID: 26514686 PMCID: PMC4966608 DOI: 10.1080/19420862.2015.1113361] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Glycosylation affects the efficacy, safety and pharmacokinetics/pharmacodynamics properties of therapeutic monoclonal antibodies (mAbs), and glycoengineering is now being used to produce mAbs with improved efficacy. In this work, a glycoengineered version of rituximab was produced by chemoenzymatic modification to generate human-like N-glycosylation with α 2,6 linked sialic acid. This modified rituximab was comprehensively characterized by liquid chromatography-mass spectrometry and compared to commercially available rituximab. As anticipated, the majority of N-glycans were converted to α 2,6 linked sialic acid, in contrast to CHO-produced rituximab, which only contains α 2,3 linked sialic acid. Typical posttranslational modifications, such as pyro-glutamic acid formation at the N-terminus, oxidation at methionine, deamidation at asparagine, and disulfide linkages were also characterized in both the commercial and glycoengineered mAbs using multiple enzymatic digestion and mass spectrometric analysis. The comparative study reveals that the glycoengineering approach does not cause any additional posttranslational modifications in the antibody except the specific transformation of the glycoforms, demonstrating the mildness and efficiency of the chemoenzymatic approach for glycoengineering of therapeutic antibodies.
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Affiliation(s)
- Renpeng Liu
- a New England Biolabs Inc. , Ipswich , MA 01938
| | - John Giddens
- b Department of Chemistry & Biochemistry ; University of Maryland , College Park , MD 20742
| | | | | | - Lai-Xi Wang
- b Department of Chemistry & Biochemistry ; University of Maryland , College Park , MD 20742
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13
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Baumann AMT, Bakkers MJG, Buettner FFR, Hartmann M, Grove M, Langereis MA, de Groot RJ, Mühlenhoff M. 9-O-Acetylation of sialic acids is catalysed by CASD1 via a covalent acetyl-enzyme intermediate. Nat Commun 2015; 6:7673. [PMID: 26169044 PMCID: PMC4510713 DOI: 10.1038/ncomms8673] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 06/01/2015] [Indexed: 12/13/2022] Open
Abstract
Sialic acids, terminal sugars of glycoproteins and glycolipids, play important roles in development, cellular recognition processes and host–pathogen interactions. A common modification of sialic acids is 9-O-acetylation, which has been implicated in sialoglycan recognition, ganglioside biology, and the survival and drug resistance of acute lymphoblastic leukaemia cells. Despite many functional implications, the molecular basis of 9-O-acetylation has remained elusive thus far. Following cellular approaches, including selective gene knockout by CRISPR/Cas genome editing, we here show that CASD1—a previously identified human candidate gene—is essential for sialic acid 9-O-acetylation. In vitro assays with the purified N-terminal luminal domain of CASD1 demonstrate transfer of acetyl groups from acetyl-coenzyme A to CMP-activated sialic acid and formation of a covalent acetyl-enzyme intermediate. Our study provides direct evidence that CASD1 is a sialate O-acetyltransferase and serves as key enzyme in the biosynthesis of 9-O-acetylated sialoglycans. 9-O-Acetylation is one of the most common modifications of sialic acids, implicated in sialoglycan recognition and ganglioside biology. Here, the authors show that the key enzyme for the biosynthesis of 9-O-acetylated sialoglycans is CASD1, which uses CMP-activated sialic acid as acceptor substrate.![]()
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Affiliation(s)
- Anna-Maria T Baumann
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
| | - Mark J G Bakkers
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Falk F R Buettner
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
| | - Maike Hartmann
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
| | - Melanie Grove
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
| | - Martijn A Langereis
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Raoul J de Groot
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Martina Mühlenhoff
- Institute of Cellular Chemistry, Hannover Medical School, D-30623 Hannover, Germany
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14
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Löfling J, Lyi SM, Parrish CR, Varki A. Canine and feline parvoviruses preferentially recognize the non-human cell surface sialic acid N-glycolylneuraminic acid. Virology 2013; 440:89-96. [PMID: 23497940 DOI: 10.1016/j.virol.2013.02.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 02/12/2013] [Accepted: 02/13/2013] [Indexed: 12/27/2022]
Abstract
Feline panleukopenia virus (FPV) is a pathogen whose canine-adapted form (canine parvovirus (CPV)) emerged in 1978. These viruses infect by binding host transferrin receptor type-1 (TfR), but also hemagglutinate erythrocytes. We show that hemagglutination involves selective recognition of the non-human sialic acid N-glycolylneuraminic acid (Neu5Gc) but not N-acetylneuraminic acid (Neu5Ac), which differs by only one oxygen atom from Neu5Gc. Overexpression of α2-6 sialyltransferase did not change binding, indicating that both α2-3 and α2-6 linkages are recognized. However, Neu5Gc expression on target cells did not enhance CPV or FPV infection in vitro. Thus, the conserved Neu5Gc-binding preference of these viruses likely plays a role in the natural history of the virus in vivo. Further studies must clarify relationships between virus infection and host Neu5Gc expression. As a first step, we show that transcripts of CMAH (which generates Neu5Gc from Neu5Ac) are at very low levels in Western dog breed cells.
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Affiliation(s)
- Jonas Löfling
- Department of Medicine, Center for Academic Research and Training in Anthropogeny, 9500 Gilman Drive, University of California, San Diego, La Jolla, CA 92093, USA
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15
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Guérardel Y, Chang LY, Fujita A, Coddeville B, Maes E, Sato C, Harduin-Lepers A, Kubokawa K, Kitajima K. Sialome analysis of the cephalochordate Branchiostoma belcheri, a key organism for vertebrate evolution. Glycobiology 2011; 22:479-91. [PMID: 22057003 DOI: 10.1093/glycob/cwr155] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Sialic acid, a common terminal substitution of glycoconjugates, has been so far consistently identified in all vertebrates as well as in a growing number of bacterial species. It is assumed to be widely distributed among animal species of the deuterostome phylum, based on its identification in few echinoderm and all vertebrate species. However, whole sections of deuterostome, especially those intermediate species between invertebrates and vertebrates including cephalochordates, urochordates and hemichordates, are still unexplored in term of sialylation capacities. The discovery of functional sialic acid machinery in some of these species may shed new light onto the evolution of glycosylation capacities in deuterostome lineage. In a first approach, we investigated the sialylation pattern of a cephalocordate species, Branchiostoma belcheri, which occupies a strategic phylogenetic position to understand the transition of invertebrates toward vertebrates. Structural analysis of B. belcheri glycoconjugates established that this organism synthesizes large quantities of various sialic acids, some of which present rare or novel structures such as methylated sialic acids. These sialic acids were shown to be mainly associated with mono- and disialylated core 1-type O-glycans. Moreover, screening of the animal organs revealed the existence of exquisite tissue specificity in the distribution of sialic acids. Description of sialylation profiles was then correlated with the expression patterns of key enzymes involved in the biosynthesis of major forms of sialic acids, which provides the first complete overview of the sialylation patterns in cephalochordates.
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Affiliation(s)
- Yann Guérardel
- Université de Lille 1, Unité de Glycobiologie Structurale et Fonctionnelle, UGSF, F-59650 Villeneuve d'Ascq, France.
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16
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Arming S, Wipfler D, Mayr J, Merling A, Vilas U, Schauer R, Schwartz-Albiez R, Vlasak R. The human Cas1 protein: a sialic acid-specific O-acetyltransferase? Glycobiology 2011; 21:553-64. [PMID: 20947662 PMCID: PMC7108626 DOI: 10.1093/glycob/cwq153] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Sialic acids are important sugars at the reducing end of glycoproteins and glycolipids. They are among many other functions involved in cell-cell interactions, host-pathogen recognition and the regulation of serum half-life of glycoproteins. An important modification of sialic acids is O-acetylation, which can alter or mask the biological properties of the parent sialic acid molecule. The nature of mammalian sialate-O-acetyltransferases (EC 2.3.1.45) involved in their biosynthesis is still unknown. We have identified the human CasD1 (capsule structure1 domain containing 1) gene as a candidate to encode the elusive enzyme. The human CasD1 gene encodes a protein with a serine-glycine-asparagine-histidine hydrolase domain and a hydrophobic transmembrane domain. Expression of the Cas1 protein tagged with enhanced green fluorescent protein in mammalian and insect cells directed the protein to the medial and trans-cisternae of the Golgi. Overexpression of the Cas1 protein in combination with α-N-acetyl-neuraminide α-2,8-sialyltransferase 1 (GD3 synthase) resulted in an up to 40% increased biosynthesis of 7-O-acetylated ganglioside GD3. By quantitative real-time polymerase chain reaction, we found up to 5-fold increase in CasD1 mRNA in tumor cells overexpressing O-Ac-GD3. CasD1-specific small interfering RNA reduced O-acetylation in tumor cells. These results suggest that the human Cas1 protein is directly involved in O-acetylation of α2-8-linked sialic acids.
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Affiliation(s)
- Sigrid Arming
- Department of Molecular Biology, University Salzburg, Austria
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17
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Srinivasan GV, Schauer R. Assays of sialate-O-acetyltransferases and sialate-O-acetylesterases. Glycoconj J 2009; 26:935-44. [PMID: 18566887 DOI: 10.1007/s10719-008-9131-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 03/20/2008] [Accepted: 03/26/2008] [Indexed: 10/21/2022]
Abstract
The O-acetylation of sialic acids is one of the most frequent modifications of these monosaccharides and modulates many cell biological and pathological events. Sialic acid-specific O-acetyltransferases and O-acetylesterases are responsible for the metabolism of esterified sialic acids. Assays were developed for the analysis of the activities and specificities of these enzymes. The methods had to be varied in dependence on the substrate assayed, the kind of biological source, and the state of enzyme purity. With the new techniques the primary site of O-acetyl incorporation at C-7, catalyzed by the animal sialate-O-acetyltransferases studied, was ascertained. Correspondingly, this enzyme, for example from bovine submandibular gland, can be denominated as AcCoA:sialate-7-O-acetyltransferase (EC 2.3.1.45). Methods for assaying the activity of esterases de-O-acetylating sialic acids and their metabolic cooperation with the O-acetyltransferases are presented.
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Affiliation(s)
- G Vinayaga Srinivasan
- Biochemisches Institut, Christian-Albrechts-Universität, Olshausenstr. 40, 24098 Kiel, Germany
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18
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Mandal C, Srinivasan GV, Chowdhury S, Chandra S, Mandal C, Schauer R, Mandal C. High level of sialate-O-acetyltransferase activity in lymphoblasts of childhood acute lymphoblastic leukaemia (ALL): enzyme characterization and correlation with disease status. Glycoconj J 2008; 26:57-73. [PMID: 18677580 DOI: 10.1007/s10719-008-9163-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 06/13/2008] [Accepted: 06/16/2008] [Indexed: 11/27/2022]
Abstract
Previous studies had established an over-expression of 9-O-acetylated sialoglycoproteins (Neu5,9Ac(2)-GPs) on lymphoblasts of childhood acute lymphoblastic leukaemia (ALL). Here, we report the discovery and characterization of sialate-O-acetyltransferase enzyme in ALL-cell lines and lymphoblasts from bone marrow of children diagnosed with B- and T-ALL. We observed a positive correlation between the enhanced sialate-O-acetyltransferase activity and the enhanced expression of Neu5,9Ac(2)-GPs in these lymphoblasts. Sialate-O-acetyltransferase activity in cell lysates or microsomal fractions of lymphoblasts of patients was always higher than that in healthy donors reaching up to 22-fold in microsomes. Additionally, the V (max) of this enzymatic reaction with AcCoA was over threefold higher in microsomal fractions of lymphoblasts. The enzyme bound to the microsomal fractions showed high activity with CMP-N-acetylneuraminic acid, ganglioside GD3 and endogenous sialic acid as substrates. N-acetyl-7-O-acetylneuraminic acid was the main reaction product, as detected by radio-thin-layer chromatography and fluorimetrically coupled radio-high-performance liquid chromatography. CMP and coenzyme A inhibited the microsomal enzyme. Sialate-O-acetyltransferase activity increased at the diagnosis of leukaemia, decreased with clinical remission and sharply increased again in relapsed patients as determined by radiometric-assay. A newly-developed non-radioactive ELISA can quickly detect sialate-O-acetyltransferase, and thus, may become a suitable tool for ALL-monitoring in larger scale. This is the first report on sialate-O-acetyltransferase in ALL being one of the few descriptions of an enzyme of this type in human.
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Affiliation(s)
- Chandan Mandal
- Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, 4 Raja S.C. Mullick Road, Jadavpur, Kolkata 700 032, India
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19
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Yu H, Chokhawala H, Huang S, Chen X. One-pot three-enzyme chemoenzymatic approach to the synthesis of sialosides containing natural and non-natural functionalities. Nat Protoc 2007; 1:2485-92. [PMID: 17406495 PMCID: PMC2586341 DOI: 10.1038/nprot.2006.401] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chemoenzymatic synthesis, which combines the flexibility of chemical synthesis and the high selectivity of enzymatic synthesis, is a powerful approach to obtain complex carbohydrates. It is a preferred method for synthesizing sialic acid-containing structures, including those with diverse naturally occurring and non-natural sialic acid forms, different sialyl linkages and different glycans that link to the sialic acid. Starting from N-acetylmannosamine, mannose or their chemically or enzymatically modified derivatives, sialic acid aldolase-catalyzed condensation reaction leads to the formation of sialic acids and their derivatives. These compounds are subsequently activated by a CMP-sialic acid synthetase and transferred to a wide range of suitable acceptors by a suitable sialyltransferase for the formation of sialosides containing natural and non-natural functionalities. The three-enzyme coupled synthesis of sialosides can be carried out in one pot without the isolation of intermediates. The time for synthesis is 4-18 h. Purification and characterization of the product can be completed within 2-3 d.
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Affiliation(s)
| | | | | | - Xi Chen
- Correspondence should be addressed to X.C. , Tel: 530-754-6037; Fax: 530-752-8995; webpage: http://chemgroups.ucdavis.edu/~chen/home.htm
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20
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Lrhorfi LA, Srinivasan GV, Schauer R. Properties and partial purification of sialate-O-acetyltransferase from bovine submandibular glands. Biol Chem 2007; 388:297-306. [PMID: 17338637 DOI: 10.1515/bc.2007.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The O-acetylation of sialic acids in various positions is a frequent modification of these residues in glycoproteins and glycolipids of higher animals and some bacteria. Sialic acid O-acetylation is involved in the regulation of many cell biological and pathophysiological events. Since the properties and the structural and molecular genetic aspects of the eukaryotic sialate O-acetyltransferases are not yet known, we attempted to isolate the enzyme from bovine submandibular glands. O-Acetyltransferase was solubilised from its microsomal location with a zwitterionic detergent and enriched by approximately 50-fold in three steps, including affinity chromatography on coenzyme A. It exhibits a molecular mass of 150-160 kDa. Evidence was obtained for the putative existence of a low-molecular-mass, dialysable enzyme activator. The enzyme showed best activity with CMP-N-acetylneuraminic acid (CMP-Neu5Ac), followed by N-acetylneuraminic acid (Neu5Ac). These compounds, as well as AcCoA, have high affinity for both the microsome-bound and the partially purified O-acetyltransferase. CoA is a strong inhibitor. N-Acetyl-9-O-acetylneuraminic acid was found to be the main reaction product. No evidence was obtained for the involvement of an isomerase that might be responsible for the migration of O-acetyl groups within the sialic acid side chain.
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Affiliation(s)
- L Aicha Lrhorfi
- Biochemisches Institut, Christian-Albrechts-Universität, Olshausenstr. 40, D-24098 Kiel, Germany
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21
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Argüeso P, Sumiyoshi M. Characterization of a carbohydrate epitope defined by the monoclonal antibody H185: sialic acid O-acetylation on epithelial cell-surface mucins. Glycobiology 2006; 16:1219-28. [PMID: 16940404 PMCID: PMC1976397 DOI: 10.1093/glycob/cwl041] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sialic acids comprise a large family of derivatives of neuraminic acid containing methyl, acetyl, sulfate, and phosphate among other groups, which confer specific physicochemical properties (e.g., hydrophobicity and resistance to hydrolases) to the molecules carrying them. Several years ago, a monoclonal antibody, designated H185, was developed, which binds to cell membranes of human corneal, conjunctival, laryngeal, and vaginal epithelia and whose distribution is altered on the ocular surface of patients with keratinizing disease. Recent findings using immunoprecipitation and immunodepletion techniques have demonstrated that, in human corneal epithelial cells, the H185 antigen is carried by the membrane-associated mucin MUC16. In this study, we show that the H185 epitope on human corneal cells and in tear fluid is an O-acetylated sialic acid epitope that can be selectively hydrolyzed in an enzyme-concentration-dependent manner by sialidase from Arthrobacter ureafaciens and to a lesser extent by sialidases from Newcastle disease virus, Clostridium perfringens, and Streptococcus pneumoniae. Binding of the H185 antibody was impaired by treatment of tear fluid with a recombinant 9-O-acetylesterase from influenza C virus. Two O-acetyl derivatives, Neu5,7Ac(2) and Neu5,9Ac(2), were identified in human tear fluid by fluorometric high-performance liquid chromatography (HPLC) and electrospray mass spectrometry (MS). Immunoprecipitation of the H185 epitope from human corneal epithelial cells revealed that Neu5,9Ac(2) was the major derivative on the mucin isolate. These results indicate that exposed wet-surfaced epithelia are decorated with O-acetyl sialic acid derivatives on membrane-associated mucins and suggest that O-acetylation on cell surfaces may protect against pathogen infection by preventing degradation of membrane-associated mucins.
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Affiliation(s)
- Pablo Argüeso
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114-2508, USA.
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22
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Chen HY, Challa AK, Varki A. 9-O-acetylation of exogenously added ganglioside GD3. The GD3 molecule induces its own O-acetylation machinery. J Biol Chem 2006; 281:7825-33. [PMID: 16434401 DOI: 10.1074/jbc.m512379200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Sialic acids are sometimes 9-O-acetylated in a developmentally regulated and cell-type-specific manner. Cells naturally expressing the disialoganglioside GD3 often O-acetylate the terminal sialic acid residue, giving 9-O-acetyl-GD3 (9AcGD3), a marker of neural differentiation and malignant transformation. We also reported that Chinese hamster ovary cells transfected with GD3 synthase can spontaneously O-acetylate some of the newly synthesized GD3. It is unclear whether such phenomena result from induction of the 9-O-acetylation machinery and whether induction is caused by the GD3 synthase protein or by the GD3 molecule itself. We now show that exogenously added GD3 rapidly incorporates into the plasma membrane of Chinese hamster ovary cells, and 9AcGD3 is detected after approximately 6 h. The incorporated GD3 and newly synthesized 9AcGD3 have a half-life of approximately 24 h. This phenomenon is also seen in other cell types, such as human diploid fibroblasts. Inhibitors of gene transcription, protein translation, or endoplasmic reticulum-to-Golgi transport each prevent induction of 9-O-acetylation, without affecting GD3 incorporation. Inhibition of the initial clathrin-independent internalization of incorporated GD3 also blocks induction of 9-O-acetylation. Thus, new synthesis of one or more components of the 9-O-acetylation machinery is induced by incorporation and internalization of GD3. Prepriming with structurally related gangliosides fails to accelerate the onset of 9-O-acetylation of subsequently added GD3, indicating a requirement for specific recognition of GD3. To our knowledge, this is the first example wherein a newly expressed or exogenously introduced ganglioside induces de novo synthesis of an enzymatic machinery to modify itself, and the first evidence for a mechanism of induction of sialic acid O-acetylation.
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Affiliation(s)
- Helen Y Chen
- Glycobiology Research and Training Center, Department of Medicine, University of California San Diego, La Jolla, California 92093-0687, USA
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23
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Lewis AL, Nizet V, Varki A. Discovery and characterization of sialic acid O-acetylation in group B Streptococcus. Proc Natl Acad Sci U S A 2004; 101:11123-8. [PMID: 15263085 PMCID: PMC503750 DOI: 10.1073/pnas.0403010101] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Group B Streptococcus (GBS) is the leading cause of human neonatal sepsis and meningitis. The GBS capsular polysaccharide is a major virulence factor and the active principle of vaccines in phase II trials. All GBS capsules have a terminal alpha 2-3-linked sialic acid [N-acetylneuraminic acid (Neu5Ac)], which interferes with complement-mediated killing. We show here that some of the Neu5Ac residues of the GBS type III capsule are O-acetylated at carbon position 7, 8, or 9, a major modification evidently missed in previous studies. Data are consistent with initial O-acetylation at position 7, and subsequent migration of the O-acetyl ester at positions 8 and 9. O-acetylation was also present on several other GBS serotypes (Ia, Ib, II, V, and VI). Deletion of the CMP-Neu5Ac synthase gene neuA by precise, in-frame allelic replacement gave intracellular accumulation of O-acetylated Neu5Ac, whereas overexpression markedly decreased O-acetylation. Given the known GBS Neu5Ac biosynthesis pathway, these data indicate that O-acetylation occurs on free Neu5Ac, competing with the CMP-Neu5Ac synthase. O-acetylation often generates immunogenic epitopes on bacterial capsular polysaccharides and can modulate human alternate pathway complement activation. Thus, our discovery has important implications for GBS pathogenicity, immunogenicity, and vaccine design.
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Affiliation(s)
- Amanda L Lewis
- Division of Biological Sciences, Glycobiology Research and Training Center, University of California at San Diego, La Jolla, CA 92093-0687, USA
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24
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Shen Y, Tiralongo J, Kohla G, Schauer R. Regulation of sialic acid O-acetylation in human colon mucosa. Biol Chem 2004; 385:145-52. [PMID: 15101557 DOI: 10.1515/bc.2004.033] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The expression of O-acetylated sialic acids in human colonic mucins is developmentally regulated, and a reduction of O-acetylation has been found to be associated with the early stages of colorectal cancer. Despite this, however, little is known about the enzymatic process of sialic acid O-acetylation in human colonic mucosa. Recently, we have reported on a human colon sialate-7(9)-O-acetyltransferase capable of incorporating acetyl groups into sialic acids at the nucleotide-sugar level [Shen et al., Biol. Chem. 383 (2002), 307-317]. In this report, we show that the CMP-N-acetyl-neuraminic acid (CMP-Neu5Ac) and acetyl-CoA (AcCoA) transporters are critical components for the O-acetylation of CMP-Neu5Ac in Golgi lumen, with specific inhibition of either transporter leading to a reduction in the formation of CMP-5-N-acetyl-9-O-acetyl-neuraminic acid (CMP-Neu5,9Ac2). Moreover, the finding that 5-N-acetyl-9-O-acetyl-neuraminic acid (Neu5,9Ac2 could be transferred from neo-synthesised CMP-Neu5,9Ac2 to endogenous glycoproteins in the same Golgi vesicles, together with the observation that asialofetuin and asialo-human colon mucin are much better acceptors for Neu5,9Ac2 than asialo-bovine submandibular gland mucin, suggests that a sialyltransferase exists that preferentially utilises CMP-Neu5,9Ac2 as the donor substrate, transferring Neu5,9Ac2 to terminal Galbeta1,3(4)R- residues.
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Affiliation(s)
- Yanqin Shen
- Biochemisches Institut, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
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25
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Satake H, Chen HY, Varki A. Genes modulated by expression of GD3 synthase in Chinese hamster ovary cells. Evidence that the Tis21 gene is involved in the induction of GD3 9-O-acetylation. J Biol Chem 2003; 278:7942-8. [PMID: 12493756 DOI: 10.1074/jbc.m210565200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
9-O-Acetylation is a common sialic acid modification, expressed in a developmentally regulated and tissue/cell type-specific manner. The relevant 9-O-acetyltransferase(s) have not been isolated or cloned; nor have mechanisms for their regulation been elucidated. We previously showed that transfection of the GD3 synthase (ST8Sia-I) gene into Chinese hamster ovary (CHO)-K1 cells gave expression of not only the disialoganglioside GD3 but also 9-O-acetyl-GD3. We now use differential display PCR between wild type CHO-K1 cells and clones stably expressing GD3 synthase (CHO-GD3 cells) to detect any increased expression of other genes and explore the possible induction of a 9-O-acetyltransferase. The four CHO mRNAs showing major up-regulation were homologous to VCAM-1, Tis21, the KC-protein-like protein, and a functionally unknown type II transmembrane protein. A moderate increase in expression of the FxC1 and SPR-1 genes was also seen. Interestingly, these are different from genes observed by others to be up-regulated after transfection of GD3 synthase into a neuroblastoma cell line. We also isolated a CHO-GD3 mutant lacking 9-O-acetyl-GD3 following chemical mutagenesis (CHO-GD3-OAc(-)). Analysis of the above differential display PCR-derived genes in these cells showed that expression of Tis21 was selectively reduced. Transfection of a mouse Tis21 cDNA into the CHO-GD3-OAc(-) mutant cells restored 9-O-acetyl-GD3 expression. Since the only major gangliosides expressed by CHO-GD3 cells are GD3 and 9-O-acetyl-GD3 (in addition to GM3, the predominant ganglioside type in wild-type CHO-K1 cells), we conclude that GD3 enhances its own 9-O-acetylation via induction of Tis21. This is the first known nuclear inducible factor for 9-O-acetylation and also the first proof that 9-O-acetylation can be directly regulated by GD3 synthase. Finally, transfection of CHO-GD3-OAc(-) mutant cells with ST6Gal-I induced 9-O-acetylation specifically on sialylated N-glycans, in a manner similar to wild-type cells. This indicates separate machineries for 9-O-acetylation on alpha2-8-linked sialic acids of gangliosides and on alpha2-6-linked sialic acids on N-glycans.
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Affiliation(s)
- Honoo Satake
- Glycobiology Research and Training Center, Department of Medicine, University of California, San Diego, La Jolla 92093-0687, USA
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26
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Martin LT, Verhagen A, Varki A. Recombinant influenza C hemagglutinin-esterase as a probe for sialic acid 9-O-acetylation. Methods Enzymol 2003; 363:489-98. [PMID: 14579598 DOI: 10.1016/s0076-6879(03)01074-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Laura T Martin
- Departments of Medicine and Cellular Molecular Medicine, University of California-San Diego, School of Medicine, La Jolla, California 92093, USA
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27
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Abstract
Lipid and glycolipid mediators are important messengers of the adaptive responses to stress, including apoptosis. In mammalian cells, the intracellular accumulation of ganglioside GD3, an acidic glycosphingolipid, contributes to mitochondrial damage, a crucial event during the apoptopic program. GD3 is a minor ganglioside in most normal tissues. Its expression increases during development and in pathological conditions such as cancer and neurodegenerative disorders. Intriguingly, GD3 can mediate additional biological events such as cell proliferation and differentiation. These diverse and opposing effects indicate that tightly regulated mechanisms, including 9-O-acetylation, control GD3 function, by affecting intracellular levels, localization and structure of GD3, and eventually dictate biological outcomes and cell fate decisions.
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Affiliation(s)
- Florence Malisan
- Department of Experimental Medicine and Biochemical Sciences, University Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.
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28
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Affiliation(s)
- Helen Y Chen
- Glycobiology Research and Training Center, Department of Medicine and Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
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29
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Abstract
Lipid and glycolipid mediators are important components of the adaptive responses to stress, including apoptosis. In mammalian cells, the intracellular accumulation of ganglioside GD3, an acidic glycosphingolipid, contributes to mitochondrial damage, a crucial event during the apoptotic program. GD3 is a minor ganglioside in most normal tissues. Its expression increases during development and in pathological conditions such as cancer and neurodegenerative disorders. Interestingly, GD3 expression also increases with the normal ageing process. Moreover, GD3 can also mediate biological events like proliferation and differentiation. Since organism integrity requires a tight balance between cell proliferation, apoptosis and senescence, controlling the intracellular level of GD3 appears of particular importance for cell fate determination.
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Affiliation(s)
- Florence Malisan
- Department of Experimental Medicine and Biochemical Sciences, University Tor Vergata, Via Montpellier, 1, 00133 Rome, Italy
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30
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Martin LT, Marth JD, Varki A, Varki NM. Genetically altered mice with different sialyltransferase deficiencies show tissue-specific alterations in sialylation and sialic acid 9-O-acetylation. J Biol Chem 2002; 277:32930-8. [PMID: 12068010 DOI: 10.1074/jbc.m203362200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycan chains on glycoconjugates traversing the Golgi apparatus are often terminated by sialic acid residues, which can also be 9-O-acetylated. This process involves competition between multiple Golgi enzymes. Expression levels of Golgi enzyme mRNAs do not always correlate with enzyme activity, which in turn cannot accurately predict glycan sequences found on cell surfaces. Here we examine the cell type-specific expression of terminal glycans in tissues of normal mice in comparison with animals deficient in ST6Gal-I (transfers alpha2-6-linked sialic acid to Galbeta1-4GlcNAc) or ST3Gal-I (transfers alpha2-3-linked sialic acid to Galbeta1-3GalNAc). Tissues of ST6Gal-I null mice showed minimal binding of an alpha2-6-sialic acid-specific lectin, indicating that no other enzyme generates Siaalpha2-6Galbeta1-4GlcNAc and that Siaalpha2-6GalNAc (sialyl-Tn) is rare in mice. However, exposed Galbeta1-4GlcNAc termini were only moderately increased, indicating that these can be partially capped by other enzymes. Indeed, Galalpha1-3Galbeta1-4GlcNAc and Fucalpha1-2Galbeta1-4GlcNAc termini were enhanced in some tissues. Many tissues of ST3Gal-I null animals showed increases in Galbeta1-3GalNAc termini, and some increases in poly-N-acetyllactosamines. However, overall expression of alpha2-3-linked sialic acid was selectively reduced only in a few instances, indicating that other ST3Gal enzymes can generate this linkage in most tissues. Highly selective losses of 9-O-acetylation of sialic acid residues were also observed, with ST6Gal-I deficiency causing loss on endothelium and ST3Gal-I deficiency giving a marked decrease on CD4(+) lymphocytes. These data demonstrate selective regulation of sialylation and 9-O-acetylation, point to cell types with potential physiological defects in null animals, and show in vivo evidence for competition between Golgi enzymes.
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Affiliation(s)
- Laura T Martin
- Glycobiology Research and Training Center, Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
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31
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Dumermuth E, Beuret N, Spiess M, Crottet P. Ubiquitous 9-O-acetylation of sialoglycoproteins restricted to the Golgi complex. J Biol Chem 2002; 277:18687-93. [PMID: 11904293 DOI: 10.1074/jbc.m109408200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
9-O-Acetylation of sialic acid is known as a cell type-specific modification of secretory and plasma membrane glycoconjugates of higher vertebrates with important functions in modulating cell-cell recognition. Using a recombinant probe derived from influenza C virus hemagglutinin, we discovered 9-O-acetylated protein in the Golgi complex of various cell lines, most of which did not display 9-O-acetylated sialic acid on the cell surface. All cell lines expressed a sulfated glycoprotein of 50 kDa (sgp50) carrying 9-O-acetylated sialic acids, which was used as a model substrate. Like gp40, the major receptor for influenza C virus of Madin-Darby canine kidney I cells, sgp50 is 9-O-acetylated on O-linked glycans. However, gp40 was not 9-O-acetylated when expressed in Madin-Darby canine kidney II or COS-7 cells. The results demonstrate the existence of two 9-O-acetylation machineries for O-glycosylated proteins with distinct substrate specificities. The widespread occurrence of 9-O-acetylated protein in the Golgi furthermore suggests an additional intracellular role for this modification.
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Affiliation(s)
- Eric Dumermuth
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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32
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Mandal C. Reply to the Brief Commentary published in Biochem. Biophys. Res. Commun. (2001) 284,1. Biochem Biophys Res Commun 2001; 288:1069-70. [PMID: 11700019 DOI: 10.1006/bbrc.2001.5857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- C Mandal
- Immunobiology Division, Indian Institute of Chemical Biology, 4, Raja S.C. Mallick Road, Calcutta 700032, India.
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33
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Schauer R, Schmid H, Pommerencke J, Iwersen M, Kohla G. Metabolism and role of O-acetylated sialic acids. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2001; 491:325-42. [PMID: 14533806 DOI: 10.1007/978-1-4615-1267-7_21] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- R Schauer
- Biochemisches Institut, Christian-Albrechts-Universität Olshausenstrasse 40, D-24098 Kiel, Germany.
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34
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Brockhausen I, Schutzbach J, Kuhns W. Glycoproteins and their relationship to human disease. ACTA ANATOMICA 2000; 161:36-78. [PMID: 9780351 DOI: 10.1159/000046450] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Glycoproteins are proteins that carry N- and O-glycosidically-linked carbohydrate chains of complex structures and functions. N-glycan chains are assembled in the endoplasmic reticulum and the Golgi by a controlled sequence of glycosyltransferase and glycosidase processing reactions involving dolichol intermediates. The assembly of O-glycans occurs in the Golgi and does not involve dolichol. For most reactions, families of glycosyltransferases exist; the expression of the individual enzymes within a family is often subject to complex regulation. The biosynthesis of N- and O-glycan is controlled at the level of gene expression, mRNA, enzyme protein activity and localization, and through substrate and cofactor concentrations at the site of synthesis. This complex regulation results in many hundreds of structures, the range of which varies in different species, cell types, tissue types, states of development and differentiation. In diseased cells, the relative proportions of these structures are often characteristically different from normal, and may be useful for the assessment of the stage of the disease and for diagnosis. Knowledge of disease-specific glycoprotein structures and their functions may be used therapeutically, in immunotherapy, in blocking cell adhesion or interfering with other binding or biological processes. Recently, some of the mechanisms underlying glycoprotein alterations in disease have been elucidated. This opens the possibility of an active interference in the disease process. The functions of glycans in diseased cells will become more clear with the tools of molecular biology and transgenic animal models.
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Affiliation(s)
- I Brockhausen
- Biochemistry Department, University of Toronto, and The Terrence Donnelly Heart Centre, St. Michael's Hospital, Toronto, Canada.
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35
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Mandal C, Chatterjee M, Sinha D. Investigation of 9-O-acetylated sialoglycoconjugates in childhood acute lymphoblastic leukaemia. Br J Haematol 2000; 110:801-12. [PMID: 11054061 DOI: 10.1046/j.1365-2141.2000.02105.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- C Mandal
- Indian Institute of Chemical Biology, Immunobiology Division, 4, Raja S. C. Mullick Road, Calcutta 700032, India.
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36
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Lu CQ, Lu J, Wang BL, Cui YZ. Changes in ganglioside contents, plasma sialic acid and cAMP levels in experimental hepatoma in mice. Mol Cell Biochem 2000; 207:29-33. [PMID: 10888223 DOI: 10.1023/a:1007029927664] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The present study was designed to assess whether changes in glycolipids and cyclic AMP contents might serve as markers for the diagnosis of malignancy in the liver. The experimental model was a transplantable murine hepatoma. Experimental mice were divided into three groups: (1) a therapeutic group, which had been transplanted with hepatoma and treated with the antimetabolism drug 5-fluorouracil (0.2 mg/day i.p.), (2) a control group, which had been transplanted with hepatoma and treated with 0.2 ml 0.9% NaCl/day and (3) a normal group of mice. The ganglioside and cAMP contents in the hepatoma tissue, plasma cAMP, total- and lipid-bound sialic acid levels and red blood cell membrane sialic acid levels were determined. Results showed that the ganglioside content, total and lipid-bound sialic acid levels in the control group were significantly higher than those in the livers of normal mice (p < 0.01) while these respective values in the therapeutic group were significantly lower than those in the control group (p < 0.01). The cAMP levels of tumor tissues and plasma in the control group were lower than those in normal mice. No significant difference in red blood cell membrane sialic acid content was observed between the therapeutic and control groups though levels for both were higher than those in normal mice. These results indicate that ganglioside content and sialic acid levels in hepatoma tissues were significantly elevated, and cAMP levels in hepatoma tissues were significantly decreased during proliferation and abnormal differentiation.
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Affiliation(s)
- C Q Lu
- Department of Biochemistry, Wannan Medical College, Wuhu, Anhui, China
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37
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Abstract
Glycoproteins with O-glycosidically linked carbohydrate chains of complex structures and functions are found in secretions and on the cell surfaces of cancer cells. The structures of O-glycans are often unusual or abnormal in cancer, and greatly contribute to the phenotype and biology of cancer cells. Some of the mechanisms of changes in O-glycosylation pathways have been determined in cancer model systems. However, O-glycan biosynthesis is a complex process that is still poorly understood. The glycosyltransferases and sulfotransferases that synthesize O-glycans appear to exist as families of related enzymes of which individual members are expressed in a tissue- and growth-specific fashion. Studies of their regulation in cancer may reveal the connection between cancerous transformation and glycosylation which may help to understand and control the abnormal biology of tumor cells. Cancer diagnosis may be based on the appearance of certain glycosylated epitopes, and therapeutic avenues have been designed to attack cancer cells via their glycans.
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Affiliation(s)
- I Brockhausen
- Department of Biochemistry, University of Toronto, Oncology Research, Toronto Hospital, 67 College Street, Toronto, Ont., Canada.
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38
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Takematsu H, Diaz S, Stoddart A, Zhang Y, Varki A. Lysosomal and cytosolic sialic acid 9-O-acetylesterase activities can Be encoded by one gene via differential usage of a signal peptide-encoding exon at the N terminus. J Biol Chem 1999; 274:25623-31. [PMID: 10464298 DOI: 10.1074/jbc.274.36.25623] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
9-O-Acetylation is one of the most common modifications of sialic acids, and it can affect several sialic acid-mediated recognition phenomena. We previously reported a cDNA encoding a lysosomal sialic acid-specific 9-O-acetylesterase, which traverses the endoplasmic reticulum-Golgi pathway and localizes primarily to lysosomes and endosomes. In this study, we report a variant cDNA derived from the same gene that contains a different 5' region. This cDNA has a putative open reading frame lacking a signal peptide-encoding sequence and is thus a candidate for the previously described cytosolic sialic acid 9-O-acetylesterase activity. Epitope-tagged constructs confirm that the new sequence causes the protein product to be targeted to the cytosol and has esterase activity. Using reverse transcription-polymerase chain reaction to distinguish the two forms of message, we show that although the lysosomal sialic acid-specific 9-O-acetylesterase message has a widespread pattern of expression in adult mouse tissues, this cytosolic sialic acid 9-O-acetylesterase form has a rather restricted distribution, with the strongest expression in the liver, ovary, and brain. Using a polyclonal antibody directed against the 69-amino acid region common to both proteins, we confirmed that the expression of glycosylated and nonglycosylated polypeptides occurred in appropriate subcellular fractions of normal mouse tissues. Rodent liver polypeptides reacting to the antibody also co-purify with previously described lysosomal sialic acid esterase activity and at least a portion of the cytosolic activity. Thus, two sialic acid 9-O-acetylesterases found in very different subcellular compartments can be encoded by a single gene by differential usage of a signal peptide-encoding exon at the N terminus. The 5'-rapid amplification of cDNA ends results and the differences in tissue-specific expression suggest that expression of these two products may be differentially regulated by independent promoters.
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Affiliation(s)
- H Takematsu
- Glycobiology Research and Training Center, Divisions of Hematology-Oncology and Cellular and Molecular Medicine, University of California San Diego, La Jolla, California 92093, USA
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39
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Ueda T, Kajita K, Fujimori O. Histochemical studies on sialic acids in the epididymis during post-natal development of the rat. THE HISTOCHEMICAL JOURNAL 1998; 30:667-76. [PMID: 9870767 DOI: 10.1023/a:1003400307405] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A variety of sialic acids contained in the rat epididymis during post-natal development were examined by means of lectin and carbohydrate histochemistry. Epididymides from male Sprague-Dawley rats on post-natal days 14, 21, 30, 39, 49, 56 and 70 were fixed in Bouin's fluid and embedded routinely in paraffin wax. Hydrated sections were subjected either to the lectin methods using biotinylated Sambucus sieboldiana lectin or Maackia amurensis lectin or to the selective periodate oxidation-phenylhydrazine-thiocarbohydrazide-silver protein-physical development technique with or without saponification. The results revealed that sialic acids appeared in the epididymal epithelium at day 14, followed by particular distribution patterns corresponding to cell differentiation during days 21-39. High-level O-acetylation of sialic acids was observed in the principal cells of the initial segment and proximal caput after day 39. These results suggest that sialic acids with different linkages and O-acetylation become adult in distribution at the 'differentiation' period under the influence of androgen, before spermatozoa reach the epididymal lumen. Such carbohydrates may be correlated, at least in part, with sperm-binding sialoproteins, which increase dramatically during the window between days 21 and 39.
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Affiliation(s)
- T Ueda
- Second Department of Anatomy, Nagoya City University Medical School, Nagoya, Japan
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40
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Iwersen M, Vandamme-Feldhaus V, Schauer R. Enzymatic 4-O-acetylation of N-acetylneuraminic acid in guinea-pig liver. Glycoconj J 1998; 15:895-904. [PMID: 10052593 DOI: 10.1023/a:1006911100081] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Sialic acids from the liver and serum of guinea-pig are composed of N-acetylneuraminic acid (Neu5Ac; 85% and 61%, respectively), N-acetyl-4-O-acetylneuraminic acid (Neu4,5Ac2; 10% and 32%, respectively) and N-glycolylneuraminic acid (Neu5Gc; 5% and 7%, respectively), besides traces of N-glycolyl-4-O-acetylneuraminic acid in serum. The analysis was carried out using thin-layer chromatography, high-performance liquid chromatography, electron impact ionization mass spectrometry, and different enzymes (sialidase, sialate esterase, and sialate-pyruvate lyase after hydrolysis and purification of the sialic acids by ion-exchange chromatography). We showed that this O-acetylation of sialic acids is due to the activity of an acetyl-coenzyme A:sialate-4-O-acetyltransferase (EC 2.3.1.44), which occurs together with sialyltransferase activity in Golgi-enriched membrane fractions of guinea-pig liver. The enzyme operates optimally at 30 degrees C in 70 mM potassium phosphate buffer at pH 6.7 and in the presence of 90 mM KCI with an apparent KM for AcCoA of 0.6 1microM and a Vmax of 20 pmol/mg protein x min. The enzyme is inhibited by coenzyme A in a mixed-competitive manner (Ki = 4.2 microM), as well as by parachloromercuribenzoate, MnCl2, saponin and Triton X-100.
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Affiliation(s)
- M Iwersen
- Biochemisches Institut, Christian-Albrechts-Universität, Kiel, Germany
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41
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Shi WX, Chammas R, Varki A. Induction of sialic acid 9-O-acetylation by diverse gene products: implications for the expression cloning of sialic acid O-acetyltransferases. Glycobiology 1998; 8:199-205. [PMID: 9451030 DOI: 10.1093/glycob/8.2.199] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Sialic acids can be modified by O-acetyl esters at the 7- and/or 9-position, altering recognition by antibodies, lectins and viruses. 9(7)-O-acetylation is mediated by a sialic acid-specific O-acetyltransferase, which has proven difficult to purify. Two groups have recently isolated cDNAs possibly encoding this enzyme, by expression cloning of human melanoma libraries in COS cells expressing the substrate ganglioside GD3. Pursuing a similar approach, we have isolated additional clones that can induce 9-O-acetylation. One clone present in a melanoma library encodes a fusion protein between a bacterial tetracycline resistance gene repressor and a sequence reported to be part of the P3 plasmid. Expression of the open reading frame is necessary for inducing 9-O-acetylation, indicating that this is not a reaction to the introduction of bacterial DNA. Another clone from a rat liver cDNA library induced 9-O-acetylation on COS cells expressing alpha2-6-linked sialic acids, and encodes an open reading frame identical to the Vitamin D binding protein. However, truncation at the 5' end eliminates the amino-terminal hydrophobic signal sequence, predicting cytosolic hyperexpression of a truncated protein. Thus, diverse types of cDNAs can indirectly induce sialic acid 9-O-acetylation in the COS cell system, raising the possibility that the real enzyme may be composed of multiple subunits which would not be amenable to expression cloning. Importantly, the cDNAs we isolated are highly specific in their ability to induce 9-O-acetylation either on alpha2-6-linked sialic acids of glycoproteins (truncated vitamin D binding protein) or on the alpha2-8-linked sialic acids of gangliosides (Tetrfusion protein). These data confirm our prior suggestion that a family of O-acetyltransferases with distinctive substrate specificities exists in mammalian systems.
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Affiliation(s)
- W X Shi
- Glycobiology Program, UCSD Cancer Center, Division of Cellular and Molecular Medicine, University of California San Diego, La Jolla 92093, USA
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42
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Abstract
Sialic acids can be acetylated at the 4, 7, 8 and/or 9 position. Biological roles of these substitutions have been missed until recently because of their low abundance and lability to conventional purification methods. The recent advances in the analysis of sialic acids have allowed to demonstrate that O-acetylation has a selective but widespread distribution. The metabolism of acetylated sialic acids is under the control of two groups of enzymes, O-acetyl transferases and 9-O-acetyl esterases. O-acetyl transferases are difficult to purify, and furthermore, attempts at expression cloning have failed in isolating the true 9-O-acetyl transferase cDNA. This explains that the regulation of the selective expression of O-acetylated sialic acid in not completely understood. Acetylation of sialic acid is expressed on the outer most part of the carbohydrate moiety of membrane and secreted glycoconjugates. This particular location explains why this modification is involved in cell/cell interactions and in the non-immune protection of mucosa.
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Affiliation(s)
- A Klein
- Unité INSERM 377, Lille, France
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43
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Rosales Fritz VM, Daniotti JL, Maccioni HJ. Chinese hamster ovary cells lacking GM1 and GD1a synthesize gangliosides upon transfection with human GM2 synthase. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1354:153-8. [PMID: 9396632 DOI: 10.1016/s0167-4781(97)00117-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
GM3-positive Chinese hamster ovary cells (CHO-K1 cells) lack the ability to synthesize GM2 and the complex gangliosides GM1 and GD1a from [3H]Gal added to the culture medium. However, they acquire the ability to synthesize GM2 and to synthesize and immunoexpress complex gangliosides upon transient transfection with a cDNA encoding the human GM3:N-acetylgalactosaminyl transferase (GM2 synthase). The activities of endogenous GM1- and GD1a-synthases in the parental cell line and in cells transfected with the plasmid with or without the GM2 synthase cDNA were essentially identical and comparable in terms of specific activity with the endogenous GM3 synthase. Results indicate that glycosyltransferases acting on GM2 to produce GM1 and GD1a are constitutively present in CHO-K1 cells, and that the expression of their activities depend on the supply of the acceptor GM2. In addition, these results lend support to the notion that GM2 synthase is a key regulatory enzyme influencing the balance between simple and complex gangliosides.
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Affiliation(s)
- V M Rosales Fritz
- Centro de Investigaciones en Química Biológica de Córdoba, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina
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44
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Krishna M, Varki A. 9-O-Acetylation of sialomucins: a novel marker of murine CD4 T cells that is regulated during maturation and activation. J Exp Med 1997; 185:1997-2013. [PMID: 9166429 PMCID: PMC2196344 DOI: 10.1084/jem.185.11.1997] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/1996] [Revised: 02/25/1997] [Indexed: 02/04/2023] Open
Abstract
Terminal sialic acids on cell surface glycoconjugates can carry 9-O-acetyl esters. For technical reasons, it has previously been difficult to determine their precise distribution on different cell types. Using a recombinant soluble form of the Influenza C virus hemagglutinin-esterase as a probe for 9-O-acetylated sialic acids, we demonstrate here their preferential expression on the CD4 T cell lineage in normal B10.A mouse lymphoid organs. Of total thymocytes, 8-10% carry 9-O-acetylation; the great majority of these are the more mature PNA-, HSA-, and TCRhi medullary cells. While low levels of 9-O-acetylation are seen on some CD4/CD8 double positive (DP) and CD8 single positive (SP) cells, high levels are present primarily on 80- 85% of CD4 SP cells. Correlation with CD4 and CD8 levels suggests that 9-O-acetylation appears as an early differentiation marker as cells mature from the DP to the CD4 SP phenotype. This high degree of 9-O-acetylation is also present on 90-95% of peripheral spleen and lymph node CD4 T cells. In contrast, only a small minority of CD8 T cells and B cells show such levels of 9-O-acetylation. Among mature peripheral CD4 T lymphocytes, the highly O-acetylated cells are Mel 14(hi), CD44(lo), and CD45R(exon B)hi, features typical of naive cells. Digestions with trypsin and O-sialoglycoprotease (OSGPase) and ELISA studies of lipid extracts indicate that the 9-O-acetylated sialic acids on peripheral CD4 T cells are predominantly on O-linked mucintype glycoproteins and to a lesser degree, on sialylated glycolipids (gangliosides). In contrast, sialic acids on mucin type molecules of CD8 T cells are not O-acetylated; instead these molecules mask the recognition of O-acetylated gangliosides that seem to be present at similar levels as on CD4 cells. The 9-O-acetylated gangliosides on mouse T cells are not bound by CD60 antibodies, which recognize O-acetylated gangliosides in human T cells. Tethering 9-O-acetylated mucins with the Influenza C probe with or without secondary cross-linking did not cause activation of CD4 T cells. However, activation by other stimuli including TCR ligation is associated with a substantial decrease in surface 9-O-acetylation, primarily in the mucin glycoprotein component. Thus, 9-O-acetylation of sialic acids on cell surface mucins is a novel marker on CD4 T cells that appears on maturation and is modulated downwards upon activation.
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Affiliation(s)
- M Krishna
- Glycobiology Program, UCSD Cancer Center, the Department of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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