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Sanda M, Benicky J, Wu J, Wang Y, Makambi K, Ahn J, Smith CI, Zhao P, Zhang L, Goldman R. Increased sialylation of site specific O-glycoforms of hemopexin in liver disease. Clin Proteomics 2016; 13:24. [PMID: 27688741 PMCID: PMC5034550 DOI: 10.1186/s12014-016-9125-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 09/16/2016] [Indexed: 02/07/2023] Open
Abstract
Background Non-invasive monitoring of liver disease remains an important health issue. Liver secreted glycoproteins reflect pathophysiological states of the organ and represent a rational target for serologic monitoring. In this study, we describe sialylated O-glycoforms of liver-secreted hemopexin (HPX) and quantify them as a ratio of disialylated to monosialylated form (S-HPX). Methods We measured S-HPX in serum of participants of the HALT-C trial using a LC–MS/MS-MRM assay. Results Repeated measurements of S-HPX in the samples of 23 disease-free controls, collected at four different time points, show that the ratio remains stable in the healthy controls but increases with the progression of liver disease. The results of measurement of S-HPX in serum of participants of the HALT-C trial show that it increased significantly (Kruskal–Wallis test, p < 0.01) in liver disease as the stage of fibrosis progressed in liver biopsies. We observed a 1.7-fold increase in fibrosis defined as Ishak score 3–4 (24.9 + 14.2, n = 22) and 4.7-fold increase in cirrhosis defined as Ishak score 5–6 (68.6 + 38.5; n = 24) compared to disease-free controls (14.7 + 6.7, n = 23). S-HPX is correlated with AFP, bilirubin, INR, ALT, and AST while inversely correlated with platelet count and albumin. In an independent verification set of samples, S-HPX separated the Ishak 5–6 (n = 15) from the Ishak 3–4 (n = 15) participants with AuROC 0.84; at the same time, the Ishak 3–4 group was separated from disease-free controls (n = 15) with AuROC 0.82. Conclusion S-HPX, a measure of sialylated O-glycoforms of hemopexin, progressively increases in fibrotic and cirrhotic patient of HCV etiology and can be quantified by an LC–MS/MS-MRM assay in unfractionated serum of patients. Quantification of sialylated O-glycoforms of this liver secreted glycoprotein represents a novel measure of the stage of liver disease that could have a role in monitoring the progression of liver pathology. Electronic supplementary material The online version of this article (doi:10.1186/s12014-016-9125-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Miloslav Sanda
- Department of Oncology, Georgetown University, PS Room GD11, 3800 Reservoir Rd NW, Washington, DC 20057 USA
| | - Julius Benicky
- Department of Oncology, Georgetown University, NRB Room E207, 3970 Reservoir Rd NW, Washington, DC 20057 USA
| | - Jing Wu
- Department of Oncology, Georgetown University, NRB Room E207, 3970 Reservoir Rd NW, Washington, DC 20057 USA
| | - Yiwen Wang
- Department of Oncology, Georgetown University, NRB Room E207, 3970 Reservoir Rd NW, Washington, DC 20057 USA
| | - Kepher Makambi
- Department of Biostatistics, Bioinformatics, and Biomathematics, Georgetown University, Building D Suite 180 Room 185, 4000 Reservoir Rd NW, Washington, DC 20057 USA
| | - Jaeil Ahn
- Department of Biostatistics, Bioinformatics, and Biomathematics, Georgetown University, Basic Science Building D Room 255, 3900 Reservoir Rd NW, Washington, DC 20057 USA
| | - Coleman I Smith
- MedStar Georgetown University Transplant Institute, 2-PHC, 3800 Reservoir Rd NW, Washington, DC 20057 USA
| | - Peng Zhao
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA USA
| | - Lihua Zhang
- Department of Oncology, Georgetown University, PS Room GD11, 3800 Reservoir Rd NW, Washington, DC 20057 USA
| | - Radoslav Goldman
- Department of Oncology, Georgetown University, NRB Room E207, 3970 Reservoir Rd NW, Washington, DC 20057 USA
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Abstract
Whilst significant effort has been focused on development of tools and approaches to clinically modulate activation processes that consume platelets, the platelet receptors that initiate activation processes remain untargeted. The modulation of receptor levels is also linked to underlying platelet aging processes which influence normal platelet lifespan and also the functionality and survival of stored platelets that are used in transfusion. In this review, we will focus on platelet adhesion receptors initiating thrombus formation, and discuss how regulation of levels of these receptors impact platelet function and platelet survival.
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Affiliation(s)
- Robert K Andrews
- a Australian Centre for Blood Diseases , Monash University , Melbourne , Australia
| | - Elizabeth E Gardiner
- b Department of Cancer Biology and Therapeutics, John Curtin School of Medical Research , Australian National University , Canberra , Australia
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53
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Cordeiro OG, Chypre M, Brouard N, Rauber S, Alloush F, Romera-Hernandez M, Bénézech C, Li Z, Eckly A, Coles MC, Rot A, Yagita H, Léon C, Ludewig B, Cupedo T, Lanza F, Mueller CG. Integrin-Alpha IIb Identifies Murine Lymph Node Lymphatic Endothelial Cells Responsive to RANKL. PLoS One 2016; 11:e0151848. [PMID: 27010197 PMCID: PMC4806919 DOI: 10.1371/journal.pone.0151848] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 03/04/2016] [Indexed: 12/31/2022] Open
Abstract
Microenvironment and activation signals likely imprint heterogeneity in the lymphatic endothelial cell (LEC) population. Particularly LECs of secondary lymphoid organs are exposed to different cell types and immune stimuli. However, our understanding of the nature of LEC activation signals and their cell source within the secondary lymphoid organ in the steady state remains incomplete. Here we show that integrin alpha 2b (ITGA2b), known to be carried by platelets, megakaryocytes and hematopoietic progenitors, is expressed by a lymph node subset of LECs, residing in medullary, cortical and subcapsular sinuses. In the subcapsular sinus, the floor but not the ceiling layer expresses the integrin, being excluded from ACKR4+ LECs but overlapping with MAdCAM-1 expression. ITGA2b expression increases in response to immunization, raising the possibility that heterogeneous ITGA2b levels reflect variation in exposure to activation signals. We show that alterations of the level of receptor activator of NF-κB ligand (RANKL), by overexpression, neutralization or deletion from stromal marginal reticular cells, affected the proportion of ITGA2b+ LECs. Lymph node LECs but not peripheral LECs express RANK. In addition, we found that lymphotoxin-β receptor signaling likewise regulated the proportion of ITGA2b+ LECs. These findings demonstrate that stromal reticular cells activate LECs via RANKL and support the action of hematopoietic cell-derived lymphotoxin.
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Affiliation(s)
- Olga G. Cordeiro
- CNRS UPR 3572, University of Strasbourg, Laboratory of Immunopathology and Therapeutic Chemistry/ MEDALIS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
| | - Mélanie Chypre
- CNRS UPR 3572, University of Strasbourg, Laboratory of Immunopathology and Therapeutic Chemistry/ MEDALIS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
- Prestwick Chemical, Blvd Gonthier d'Andernach, Parc d’innovation, 67400, Illkirch, France
| | - Nathalie Brouard
- INSERM, UMR_S949, Etablissement Français du Sang-Alsace, Faculté de Médecine, Fédération de Médecine Translationnelle, Université de Strasbourg, Strasbourg, France
| | - Simon Rauber
- CNRS UPR 3572, University of Strasbourg, Laboratory of Immunopathology and Therapeutic Chemistry/ MEDALIS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
| | - Farouk Alloush
- CNRS UPR 3572, University of Strasbourg, Laboratory of Immunopathology and Therapeutic Chemistry/ MEDALIS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
| | | | - Cécile Bénézech
- BHF Centre for Cardiovascular Science, Queens Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Zhi Li
- Center for Immunology and Infection, Department of Biology, University of York, York, United Kingdom
| | - Anita Eckly
- INSERM, UMR_S949, Etablissement Français du Sang-Alsace, Faculté de Médecine, Fédération de Médecine Translationnelle, Université de Strasbourg, Strasbourg, France
| | - Mark C. Coles
- Center for Immunology and Infection, Department of Biology, University of York, York, United Kingdom
| | - Antal Rot
- Center for Immunology and Infection, Department of Biology, University of York, York, United Kingdom
| | - Hideo Yagita
- Department of Immunology, Juntendo University School of Medicine, Tokyo, 113–8421, Japan
| | - Catherine Léon
- INSERM, UMR_S949, Etablissement Français du Sang-Alsace, Faculté de Médecine, Fédération de Médecine Translationnelle, Université de Strasbourg, Strasbourg, France
| | - Burkhard Ludewig
- Institute of Immunobiology, Kantonspital St. Gallen, 9007, St. Gallen, Switzerland
| | - Tom Cupedo
- Department of Hematology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - François Lanza
- INSERM, UMR_S949, Etablissement Français du Sang-Alsace, Faculté de Médecine, Fédération de Médecine Translationnelle, Université de Strasbourg, Strasbourg, France
| | - Christopher G. Mueller
- CNRS UPR 3572, University of Strasbourg, Laboratory of Immunopathology and Therapeutic Chemistry/ MEDALIS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
- * E-mail:
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54
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Cellular O-Glycome Reporter/Amplification to explore O-glycans of living cells. Nat Methods 2015; 13:81-6. [PMID: 26619014 PMCID: PMC4697867 DOI: 10.1038/nmeth.3675] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 10/26/2015] [Indexed: 12/27/2022]
Abstract
Protein O-glycosylation plays key roles in many biological processes, but the repertoire of O-glycans synthesized by cells is difficult to determine. Here we describe a new approach termed Cellular O-Glycome Reporter/Amplification (CORA), a sensitive method to amplify and profile mucin-type O-glycans synthesized by living cells. Cells incubated with peracetylated benzyl-α-N-acetylgalactosamine (GalNAc-α-Benzyl) convert it to a large variety of modified O-glycan derivatives that are secreted from cells, allowing easy purification for analysis by HPLC and mass spectrometry (MS). CORA results in ~100–1000-fold increase in sensitivity over conventional O-glycan analyses and identifies a more complex repertoire of O-glycans in more than a dozen cell types from Homo sapiens and Mus musculus. Furthermore, CORA coupled with computational modeling allows predictions on the diversity of the human O-glycome and offers new opportunities to identify novel glycan biomarkers for human diseases.
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55
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Wihadmadyatami H, Heidinger K, Röder L, Werth S, Giptner A, Hackstein H, Knorr M, Bein G, Sachs UJ, Santoso S. Alloantibody against new platelet alloantigen (Lapa) on glycoprotein IIb is responsible for a case of fetal and neonatal alloimmune thrombocytopenia. Transfusion 2015; 55:2920-9. [DOI: 10.1111/trf.13238] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/30/2015] [Accepted: 06/09/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Hevi Wihadmadyatami
- Institute for Clinical Immunology and Transfusion Medicine; Justus Liebig University; Giessen Germany
- Department of Anatomy; Faculty of Veterinary Medicine; Universitas Gadjah Mada; Yogyakarta Indonesia
| | - Kathrin Heidinger
- Institute for Clinical Immunology and Transfusion Medicine; Justus Liebig University; Giessen Germany
| | - Lida Röder
- Institute for Clinical Immunology and Transfusion Medicine; Justus Liebig University; Giessen Germany
| | - Silke Werth
- Institute for Clinical Immunology and Transfusion Medicine; Justus Liebig University; Giessen Germany
| | - Astrid Giptner
- Institute for Clinical Immunology and Transfusion Medicine; Justus Liebig University; Giessen Germany
| | - Holger Hackstein
- Institute for Clinical Immunology and Transfusion Medicine; Justus Liebig University; Giessen Germany
| | - Martin Knorr
- Department of Paediatric Oncology and Haematology; University Clinic; Essen Germany
| | - Gregor Bein
- Institute for Clinical Immunology and Transfusion Medicine; Justus Liebig University; Giessen Germany
| | - Ulrich J. Sachs
- Institute for Clinical Immunology and Transfusion Medicine; Justus Liebig University; Giessen Germany
| | - Sentot Santoso
- Institute for Clinical Immunology and Transfusion Medicine; Justus Liebig University; Giessen Germany
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56
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Zeng J, Mi R, Wang Y, Li Y, Lin L, Yao B, Song L, van Die I, Chapman AB, Cummings RD, Jin P, Ju T. Promoters of Human Cosmc and T-synthase Genes Are Similar in Structure, Yet Different in Epigenetic Regulation. J Biol Chem 2015; 290:19018-33. [PMID: 26063800 PMCID: PMC4521027 DOI: 10.1074/jbc.m115.654244] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 05/29/2015] [Indexed: 01/31/2023] Open
Abstract
The T-synthase (core 1 β3-galactosyltransferase) and its molecular chaperone Cosmc regulate the biosynthesis of mucin type O-glycans on glycoproteins, and evidence suggests that both T-synthase and Cosmc are transcriptionally suppressed in several human diseases, although the transcriptional regulation of these two genes is not understood. Here, we characterized the promoters essential for human Cosmc and T-synthase transcription. The upstream regions of the genes lack a conventional TATA box but contain CpG islands, cCpG-I and cCpG-II for Cosmc and tCpG for T-synthase. Using luciferase reporter assays, site-directed mutagenesis, ChIP assays, and mithramycin A treatment, we identified the core promoters within cCpG-II and tCpG, which contain two binding sites for Krüppel-like transcription factors, including SP1/SP3, respectively. Methylome analysis of Tn4 B cells, which harbor a silenced Cosmc, confirmed the hypermethylation of the Cosmc core promoter but not for T-synthase. These results demonstrate that Cosmc and T-synthase are transcriptionally regulated at a basal level by the specificity protein/Krüppel-like transcription factor family of members, which explains their ubiquitous and coordinated expression, and also indicate that they are differentially epigenetically regulated beyond X chromosome imprinting. These results are important in understanding the regulation of these genes that have roles in human diseases, such as IgA nephropathy and cancer.
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Affiliation(s)
| | | | | | | | | | | | - Lina Song
- From the Departments of Biochemistry
| | - Irma van Die
- the Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands
| | - Arlene B Chapman
- Medicine, Emory University School of Medicine, Atlanta, Georgia 30322 and
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57
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Stowell SR, Ju T, Cummings RD. Protein glycosylation in cancer. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2015; 10:473-510. [PMID: 25621663 DOI: 10.1146/annurev-pathol-012414-040438] [Citation(s) in RCA: 567] [Impact Index Per Article: 63.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neoplastic transformation results in a wide variety of cellular alterations that impact the growth, survival, and general behavior of affected tissue. Although genetic alterations underpin the development of neoplastic disease, epigenetic changes can exert an equally significant effect on neoplastic transformation. Among neoplasia-associated epigenetic alterations, changes in cellular glycosylation have recently received attention as a key component of neoplastic progression. Alterations in glycosylation appear to not only directly impact cell growth and survival but also facilitate tumor-induced immunomodulation and eventual metastasis. Many of these changes may support neoplastic progression, and unique alterations in tumor-associated glycosylation may also serve as a distinct feature of cancer cells and therefore provide novel diagnostic and even therapeutic targets.
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58
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Zhong M, Zhang H, Reilly JP, Chrisitie JD, Ishihara M, Kumagai T, Azadi P, Reilly MP. ABO Blood Group as a Model for Platelet Glycan Modification in Arterial Thrombosis. Arterioscler Thromb Vasc Biol 2015; 35:1570-8. [PMID: 26044584 DOI: 10.1161/atvbaha.115.305337] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 05/22/2015] [Indexed: 01/02/2023]
Abstract
ABO blood groups have long been associated with cardiovascular disease, thrombosis, and acute coronary syndromes. Many studies over the years have shown type O blood group to be associated with lower risk of cardiovascular disease than non-type O blood groups. However, the mechanisms underlying this association remain unclear. Although ABO blood group is associated with variations in concentrations of circulating von Willebrand Factor and other endothelial cell adhesion molecules, ABO antigens are also present on several platelet surface glycoproteins and glycosphingolipids. As we highlight in this platelet-centric review, these glycomic modifications may affect platelet function in arterial thrombosis. More broadly, improving our understanding of the role of platelet glycan modifications in acute coronary syndromes may inform future diagnostics and therapeutics for cardiovascular diseases.
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Affiliation(s)
- Ming Zhong
- From the Cardiology Division, Department of Medicine, Cardiovascular Institute (M.Z., H.Z., M.P.R.) and Pulmonology, Allergy, and Critical Care Division, Department of Medicine (J.P.R., J.D.C.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Complex Carbohydrate Research Center, University of Georgia, Athens (M.I., T.K., P.A.)
| | - Hanrui Zhang
- From the Cardiology Division, Department of Medicine, Cardiovascular Institute (M.Z., H.Z., M.P.R.) and Pulmonology, Allergy, and Critical Care Division, Department of Medicine (J.P.R., J.D.C.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Complex Carbohydrate Research Center, University of Georgia, Athens (M.I., T.K., P.A.)
| | - John P Reilly
- From the Cardiology Division, Department of Medicine, Cardiovascular Institute (M.Z., H.Z., M.P.R.) and Pulmonology, Allergy, and Critical Care Division, Department of Medicine (J.P.R., J.D.C.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Complex Carbohydrate Research Center, University of Georgia, Athens (M.I., T.K., P.A.)
| | - Jason D Chrisitie
- From the Cardiology Division, Department of Medicine, Cardiovascular Institute (M.Z., H.Z., M.P.R.) and Pulmonology, Allergy, and Critical Care Division, Department of Medicine (J.P.R., J.D.C.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Complex Carbohydrate Research Center, University of Georgia, Athens (M.I., T.K., P.A.)
| | - Mayumi Ishihara
- From the Cardiology Division, Department of Medicine, Cardiovascular Institute (M.Z., H.Z., M.P.R.) and Pulmonology, Allergy, and Critical Care Division, Department of Medicine (J.P.R., J.D.C.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Complex Carbohydrate Research Center, University of Georgia, Athens (M.I., T.K., P.A.)
| | - Tadahiro Kumagai
- From the Cardiology Division, Department of Medicine, Cardiovascular Institute (M.Z., H.Z., M.P.R.) and Pulmonology, Allergy, and Critical Care Division, Department of Medicine (J.P.R., J.D.C.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Complex Carbohydrate Research Center, University of Georgia, Athens (M.I., T.K., P.A.)
| | - Parastoo Azadi
- From the Cardiology Division, Department of Medicine, Cardiovascular Institute (M.Z., H.Z., M.P.R.) and Pulmonology, Allergy, and Critical Care Division, Department of Medicine (J.P.R., J.D.C.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Complex Carbohydrate Research Center, University of Georgia, Athens (M.I., T.K., P.A.)
| | - Muredach P Reilly
- From the Cardiology Division, Department of Medicine, Cardiovascular Institute (M.Z., H.Z., M.P.R.) and Pulmonology, Allergy, and Critical Care Division, Department of Medicine (J.P.R., J.D.C.), Perelman School of Medicine, University of Pennsylvania, Philadelphia; and Complex Carbohydrate Research Center, University of Georgia, Athens (M.I., T.K., P.A.).
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59
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Smeekens JM, Chen W, Wu R. Mass spectrometric analysis of the cell surface N-glycoproteome by combining metabolic labeling and click chemistry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:604-614. [PMID: 25425172 DOI: 10.1007/s13361-014-1016-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 10/02/2014] [Accepted: 10/03/2014] [Indexed: 06/04/2023]
Abstract
Cell surface N-glycoproteins play extraordinarily important roles in cell-cell communication, cell-matrix interactions, and cellular response to environmental cues. Global analysis is exceptionally challenging because many N-glycoproteins are present at low abundances and effective separation is difficult to achieve. Here, we have developed a novel strategy integrating metabolic labeling, copper-free click chemistry, and mass spectrometry (MS)-based proteomics methods to analyze cell surface N-glycoproteins comprehensively and site-specifically. A sugar analog containing an azido group, N-azidoacetylgalactosamine, was fed to cells to label glycoproteins. Glycoproteins with the functional group on the cell surface were then bound to dibenzocyclooctyne-sulfo-biotin via copper-free click chemistry under physiological conditions. After protein extraction and digestion, glycopeptides with the biotin tag were enriched by NeutrAvidin conjugated beads. Enriched glycopeptides were deglycosylated with peptide-N-glycosidase F in heavy-oxygen water, and in the process of glycan removal, asparagine was converted to aspartic acid and tagged with 18O for MS analysis. With this strategy, 144 unique N-glycopeptides containing 152 N-glycosylation sites were identified in 110 proteins in HEK293T cells. As expected, 95% of identified glycoproteins were membrane proteins, which were highly enriched. Many sites were located on important receptors, transporters, and cluster of differentiation proteins. The experimental results demonstrated that the current method is very effective for the comprehensive and site-specific identification of the cell surface N-glycoproteome and can be extensively applied to other cell surface protein studies.
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Affiliation(s)
- Johanna M Smeekens
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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60
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Fuwa TJ, Kinoshita T, Nishida H, Nishihara S. Reduction of T antigen causes loss of hematopoietic progenitors in Drosophila through the inhibition of filopodial extensions from the hematopoietic niche. Dev Biol 2015; 401:206-19. [PMID: 25779703 DOI: 10.1016/j.ydbio.2015.03.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Revised: 02/28/2015] [Accepted: 03/05/2015] [Indexed: 12/29/2022]
Abstract
Hematopoietic stem cells (HSCs) are present in hematopoietic organs and differentiate into mature blood cells as required. Defective HSCs have been implicated in the human autoimmune disease Tn syndrome, which results from the failure of the core 1 β1,3-galactosyltransferase 1 enzyme (C1β3GalT1) to synthesize T antigen. In both mice and humans, a reduced level of T antigen is associated with a reduction in blood cell numbers. However, the precise roles of T antigen in hematopoiesis are unknown. Here, we show that the Drosophila T antigen, supplied by plasmatocytes, is essential for the regulation of HSCs. T antigen appears to be an essential factor in maintaining the extracellular environment to support filopodial extensions from niches that are responsible for transmitting signaling molecules to maintain the HSCs. In addition, our results revealed that the clotting factor, hemolectin, disrupted the hemolymph environment of C1β3GalT1 mutants. This study identified a novel mucin function for the regulation of HSCs that may be conserved in other species.
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Affiliation(s)
- Takashi J Fuwa
- Laboratory of Cell Biology, Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Takaaki Kinoshita
- Laboratory of Cell Biology, Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Hiroshi Nishida
- Laboratory of Cell Biology, Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Shoko Nishihara
- Laboratory of Cell Biology, Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan.
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Kudelka MR, Ju T, Heimburg-Molinaro J, Cummings RD. Simple sugars to complex disease--mucin-type O-glycans in cancer. Adv Cancer Res 2015; 126:53-135. [PMID: 25727146 DOI: 10.1016/bs.acr.2014.11.002] [Citation(s) in RCA: 353] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mucin-type O-glycans are a class of glycans initiated with N-acetylgalactosamine (GalNAc) α-linked primarily to Ser/Thr residues within glycoproteins and often extended or branched by sugars or saccharides. Most secretory and membrane-bound proteins receive this modification, which is important in regulating many biological processes. Alterations in mucin-type O-glycans have been described across tumor types and include expression of relatively small-sized, truncated O-glycans and altered terminal structures, both of which are associated with patient prognosis. New discoveries in the identity and expression of tumor-associated O-glycans are providing new avenues for tumor detection and treatment. This chapter describes mucin-type O-glycan biosynthesis, altered mucin-type O-glycans in primary tumors, including mechanisms for structural changes and contributions to the tumor phenotype, and clinical approaches to detect and target altered O-glycans for cancer treatment and management.
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Affiliation(s)
- Matthew R Kudelka
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Tongzhong Ju
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Richard D Cummings
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA.
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Ju T, Aryal RP, Kudelka MR, Wang Y, Cummings RD. The Cosmc connection to the Tn antigen in cancer. Cancer Biomark 2015; 14:63-81. [PMID: 24643043 DOI: 10.3233/cbm-130375] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The Tn antigen is a tumor-associated carbohydrate antigen that is not normally expressed in peripheral tissues or blood cells. Expression of this antigen, which is found in a majority of human carcinomas of all types, arises from a blockage in the normal O-glycosylation pathway in which glycans are extended from the common precursor GalNAcα1-O-Ser/Thr (Tn antigen). This precursor is generated in the Golgi apparatus on newly synthesized glycoproteins by a family of polypeptide α-N-acetylgalactosaminyltransferases (ppGalNAcTs) and then extended to the common core 1 O-glycan Galβ1-3GalNAcα1-O-Ser/Thr (T antigen) by a single enzyme termed the T-synthase (core 1 β3-galactosyltransferase or C1GalT). Formation of the active form of the T-synthase requires a unique molecular chaperone termed Cosmc, encoded by Cosmc on the X-chromosome (Xq24 in humans, Xc3 in mice). Cosmc resides in the endoplasmic reticulum (ER) and prevents misfolding, aggregation, and proteasome-dependent degradation of newly synthesized T-synthase. Loss of expression of active T-synthase or Cosmc can lead to expression of the Tn antigen, along with its sialylated version Sialyl Tn antigen as observed in several cancers. Both genetic and epigenetic pathways, in addition to potential metabolic regulation, can result in abnormal expression of the Tn antigen. Engineered expression of the Tn antigen by disruption of either C1GalT (T-syn) or Cosmc in mice is associated with a tremendous range of pathologies and engineered expression of the Tn antigen in mouse embryos leads to embryonic death. Studies indicate that many membrane glycoproteins expressing the Tn antigen and/or truncated O-glycans may be dysfunctional, due to degradation and/or misfolding. Thus, expression of normal O-glycans is associated with health and homeostasis whereas truncation of O-glycans, e.g. the Tn and/or Sialyl Tn antigens is associated with cancer and other pathologies.
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Affiliation(s)
- Tongzhong Ju
- Department of Biochemistry and the Emory Glycomics Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Rajindra P Aryal
- Department of Biochemistry and the Emory Glycomics Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Matthew R Kudelka
- Department of Biochemistry and the Emory Glycomics Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Yingchun Wang
- Department of Biochemistry and the Emory Glycomics Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Richard D Cummings
- Department of Biochemistry and the Emory Glycomics Center, Emory University School of Medicine, Atlanta, GA, USA
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Herzog BH, Fu J, Xia L. Mucin-type O-glycosylation is critical for vascular integrity. Glycobiology 2014; 24:1237-41. [PMID: 24946788 DOI: 10.1093/glycob/cwu058] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Vascular endothelial cells, in addition to many other mammalian cell types, express proteins that are highly modified with mucin-type O-glycosylation, a specific type of glycosylation that begins with the addition of an N-acetylgalactosamine moiety to serine or threonine residues within the peptide backbone. Recently, it has become evident that O-glycosylation governs the separation of blood and lymphatic vessels throughout life and plays a critical role in maintaining vascular integrity in specific tissues such as the brain and lymph node. This mini-review seeks to highlight some of these recent advances regarding in vivo functions of mucin-type O-glycans.
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Affiliation(s)
- Brett H Herzog
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Jianxin Fu
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Lijun Xia
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Burkhart JM, Gambaryan S, Watson SP, Jurk K, Walter U, Sickmann A, Heemskerk JWM, Zahedi RP. What can proteomics tell us about platelets? Circ Res 2014; 114:1204-19. [PMID: 24677239 DOI: 10.1161/circresaha.114.301598] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
More than 130 years ago, it was recognized that platelets are key mediators of hemostasis. Nowadays, it is established that platelets participate in additional physiological processes and contribute to the genesis and progression of cardiovascular diseases. Recent data indicate that the platelet proteome, defined as the complete set of expressed proteins, comprises >5000 proteins and is highly similar between different healthy individuals. Owing to their anucleate nature, platelets have limited protein synthesis. By implication, in patients experiencing platelet disorders, platelet (dys)function is almost completely attributable to alterations in protein expression and dynamic differences in post-translational modifications. Modern platelet proteomics approaches can reveal (1) quantitative changes in the abundance of thousands of proteins, (2) post-translational modifications, (3) protein-protein interactions, and (4) protein localization, while requiring only small blood donations in the range of a few milliliters. Consequently, platelet proteomics will represent an invaluable tool for characterizing the fundamental processes that affect platelet homeostasis and thus determine the roles of platelets in health and disease. In this article we provide a critical overview on the achievements, the current possibilities, and the future perspectives of platelet proteomics to study patients experiencing cardiovascular, inflammatory, and bleeding disorders.
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Affiliation(s)
- Julia M Burkhart
- From the Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Dortmund, Germany (J.M.B., A.S., R.P.Z); Institut für Klinische Biochemie und Pathobiochemie, Universitätsklinikum Würzburg, Würzburg, Germany (S.G.); Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia (S.G.); Centre for Cardiovascular Sciences, Institute for Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom (S.P.W.); Center for Thrombosis and Hemostasis, Universitätsklinikum der Johannes Gutenberg-Universität Mainz, Mainz, Germany (K.J., U.W.); Medizinisches Proteom Center, Ruhr Universität Bochum, Bochum, Germany (A.S.); Department of Chemistry, College of Physical Sciences, University of Aberdeen, Aberdeen, Scotland, United Kingdom (A.S.); and Department of Biochemistry, CARIM, Maastricht University, Maastricht, The Netherlands (J.W.M.H.)
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Aryal RP, Ju T, Cummings RD. Identification of a novel protein binding motif within the T-synthase for the molecular chaperone Cosmc. J Biol Chem 2014; 289:11630-11641. [PMID: 24616093 DOI: 10.1074/jbc.m114.555870] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Prior studies suggested that the core 1 β3-galactosyltransferase (T-synthase) is a specific client of the endoplasmic reticulum chaperone Cosmc, whose function is required for T-synthase folding, activity, and consequent synthesis of normal O-glycans in all vertebrate cells. To explore whether the T-synthase encodes a specific recognition motif for Cosmc, we used deletion mutagenesis to identify a cryptic linear and relatively hydrophobic peptide in the N-terminal stem region of the T-synthase that is essential for binding to Cosmc (Cosmc binding region within T-synthase, or CBRT). Using this sequence information, we synthesized a peptide containing CBRT and found that it directly interacts with Cosmc and also inhibits Cosmc-assisted in vitro refolding of denatured T-synthase. Moreover, engineered T-synthase carrying mutations within CBRT exhibited diminished binding to Cosmc that resulted in the formation of inactive T-synthase. To confirm the general recognition of CBRT by Cosmc, we performed a domain swap experiment in which we inserted the stem region of the T-synthase into the human β4GalT1 and found that the CBRT element can confer Cosmc binding onto the β4GalT1 chimera. Thus, CBRT is a unique recognition motif for Cosmc to promote its regulation and formation of active T-synthase and represents the first sequence-specific chaperone recognition system in the ER/Golgi required for normal protein O-glycosylation.
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Affiliation(s)
- Rajindra P Aryal
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Tongzhong Ju
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322.
| | - Richard D Cummings
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322.
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Qiao J, Shen Y, Shi M, Lu Y, Cheng J, Chen Y. Molecular cloning and characterization of rhesus monkey platelet glycoprotein Ibα, a major ligand-binding subunit of GPIb-IX-V complex. Thromb Res 2014; 133:817-25. [PMID: 24560895 DOI: 10.1016/j.thromres.2014.01.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 01/04/2014] [Accepted: 01/27/2014] [Indexed: 02/05/2023]
Abstract
INTRODUCTION Through binding to von Willebrand factor (VWF), platelet glycoprotein (GP) Ibα, the major ligand-binding subunit of the GPIb-IX-V complex, initiates platelet adhesion and aggregation in response to exposed VWF or elevated fluid-shear stress. There is little data regarding non-human primate platelet GPIbα. This study cloned and characterized rhesus monkey (Macaca Mullatta) platelet GPIbα. MATERIALS AND METHODS DNAMAN software was used for sequence analysis and alignment. N/O-glycosylation sites and 3-D structure modelling were predicted by online OGPET v1.0, NetOGlyc 1.0 Server and SWISS-MODEL, respectively. Platelet function was evaluated by ADP- or ristocetin-induced platelet aggregation. RESULTS Rhesus monkey GPIbα contains 2,268 nucleotides with an open reading frame encoding 755 amino acids. Rhesus monkey GPIbα nucleotide and protein sequences share 93.27% and 89.20% homology respectively, with human. Sequences encoding the leucine-rich repeats of rhesus monkey GPIbα share strong similarity with human, whereas PEST sequences and N/O-glycosylated residues vary. The GPIbα-binding residues for thrombin, filamin A and 14-3-3ζ are highly conserved between rhesus monkey and human. Platelet function analysis revealed monkey and human platelets respond similarly to ADP, but rhesus monkey platelets failed to respond to low doses of ristocetin where human platelets achieved 76% aggregation. However, monkey platelets aggregated in response to higher ristocetin doses. CONCLUSIONS Monkey GPIbα shares strong homology with human GPIbα, however there are some differences in rhesus monkey platelet activation through GPIbα engagement, which need to be considered when using rhesus monkey platelet to investigate platelet GPIbα function.
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Affiliation(s)
- Jianlin Qiao
- Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu 610041, China; Department of Haematology, the Affiliated Hospital of Xuzhou Medical College, Xuzhou 221002, China
| | - Yang Shen
- Australian Centre for Blood Diseases, Monash University, Melbourne, 3004, Victoria, Australia
| | - Meimei Shi
- Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yanrong Lu
- Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Jingqiu Cheng
- Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Younan Chen
- Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu 610041, China.
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Malaspina A, Collins BS, Dell A, Alter G, Onami TM. Conference report: "Functional Glycomics in HIV Type 1 Vaccine Design" workshop report, Bethesda, Maryland, April 30-May 1, 2012. AIDS Res Hum Retroviruses 2013; 29:1407-17. [PMID: 23767872 DOI: 10.1089/aid.2013.0102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A vital part of the renewed hope for a vaccine against the human immunodeficiency virus (HIV-1) is based on recent studies that have highlighted major sites of HIV-1 vulnerability that could be effectively targeted by a preventive vaccine. One of these potential vulnerabilities includes the dense cluster of carbohydrates surrounding HIV-1's envelope glycoproteins gp120 and gp41, typically referred to as the "glycan shield." Recent data from several laboratories have shown that glycans on the HIV-1 envelope form key epitopes for broadly neutralizing antibodies (bNAb). Moreover, HIV-1 envelope glycans play an important role in viral transmission, antigenicity, and immunogenicity. The recent availability of novel tools and technologies has now allowed investigators to leverage glycomic structure-function relationships in the design of candidate HIV-1 vaccines. Additionally, glycans modulate the immune response, playing an essential role in Fc receptor and complement activity. To promote cross-disciplinary collaboration and promote synergistic HIV-1- glycomics research, the National Institutes of Health (NIH) cosponsored and convened a 1.5-day workshop entitled "Functional Glycomics in HIV-1 Vaccine Design." The meeting focused on the role of glycan interactions with neutralizing antibodies, the influence of immunoglobulin G (IgG) Fc receptor glycosylation, newly available glycomics technologies, and how new information on the role of glycans could be applied in HIV-1 immunogen design strategies. This report summarizes the discussions of this workshop.
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Affiliation(s)
- Angela Malaspina
- Preclinical Research and Development Branch, Division of AIDS, U.S. National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
| | - Brenda S. Collins
- HJF-DAIDS, a Division of The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Contractor to NIAID, NIH, DHHS, Bethesda, Maryland
| | - Anne Dell
- Division of Molecular Biosciences, Imperial College London, London, United Kingdom
| | - Galit Alter
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Charlestown, Massachusetts
| | - Thandi M. Onami
- Vaccine Clinical Research Branch, Division of AIDS, U.S. National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
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Ju T, Wang Y, Aryal RP, Lehoux SD, Ding X, Kudelka MR, Cutler C, Zeng J, Wang J, Sun X, Heimburg-Molinaro J, Smith DF, Cummings RD. Tn and sialyl-Tn antigens, aberrant O-glycomics as human disease markers. Proteomics Clin Appl 2013; 7:618-31. [PMID: 23857728 DOI: 10.1002/prca.201300024] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 04/24/2013] [Indexed: 12/12/2022]
Abstract
In many different human disorders, the cellular glycome is altered. An interesting but poorly understood alteration occurs in the mucin-type O-glycome, in which there is aberrant expression of the truncated O-glycans Tn (GalNAcα1-Ser/Thr) and its sialylated version sialyl-Tn (STn) (Neu5Acα2,6GalNAcα1-Ser/Thr). Both Tn and STn are tumor-associated carbohydrate antigens and tumor biomarkers, since they are not expressed normally and appear early in tumorigenesis. Moreover, their expression is strongly associated with poor prognosis and tumor metastasis. The Tn and STn antigens are also expressed in other human diseases and disorders, such as Tn syndrome and IgA nephropathy. The major pathological mechanism for expression of the Tn and STn antigens is compromised T-synthase activity, resulting from alteration of the X-linked gene that encodes for Cosmc, a molecular chaperone specifically required for the correct folding of T-synthase to form active enzyme. This review will summarize our current understanding of the Tn and STn antigens in terms of their biochemistry and role in pathology.
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Affiliation(s)
- Tongzhong Ju
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Yingchun Wang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Rajindra P Aryal
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Sylvain D Lehoux
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Xiaokun Ding
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Matthew R Kudelka
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Christopher Cutler
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Junwei Zeng
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Jianmei Wang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Xiaodong Sun
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | | | - David F Smith
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Richard D Cummings
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
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C1galt1-deficient mice exhibit thrombocytopenia due to abnormal terminal differentiation of megakaryocytes. Blood 2013; 122:1649-57. [PMID: 23794065 DOI: 10.1182/blood-2012-12-471102] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
C1galt1 is essential for synthesis of the core 1 structure of mucin-type O-glycans. To clarify the physiological role of O-glycans in adult hematopoiesis, we exploited the interferon-inducible Mx1-Cre transgene to conditionally ablate the C1galt(flox) allele (Mx1-C1). Mx1-C1 mice exhibit severe thrombocytopenia, giant platelets, and prolonged bleeding times. Both the number and DNA ploidy of megakaryocytes in Mx1-C1 bone marrow were similar to those in wild-type (WT) mice. However, there were few proplatelets in Mx1-C1 primary megakaryocytes. Conversely, bone marrow transplanted from Mx1-C1 to WT and splenectomized Mx1-C1 mice gave rise to observations similar to those described above. The expression of GPIbα messenger RNA was unchanged in Mx1-C1 bone marrow, whereas flow cytometric and western blot analyses using megakaryocytes and platelets revealed that the expression of GPIbα protein was significantly reduced in Mx1-C1 mice. Moreover, circulating Mx1-C1 platelets exhibited an increase in the number of microtubule coils, despite normal levels of α- and β-tubulin. Our observations suggest that O-glycan is required for terminal megakaryocyte differentiation and platelet production and that the decrease in GPIbα in cells lacking O-glycan might be caused by increased proteolysis.
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Abstract
Mucin-type O-glycosylation is an evolutionarily conserved protein modification present on membrane-bound and secreted proteins. Aberrations in O-glycosylation are responsible for certain human diseases and are associated with disease risk factors. Recent studies have demonstrated essential roles for mucin-type O-glycosylation in protein secretion, stability, processing, and function. Here, we summarize our current understanding of the diverse roles of mucin-type O-glycosylation during eukaryotic development. Appreciating how this conserved modification operates in developmental processes will provide insight into its roles in human disease and disease susceptibilities.
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Affiliation(s)
- Duy T Tran
- Developmental Glycobiology Section, NIDCR, National Institutes of Health, Bethesda, Maryland 20892-4370, USA
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Mi R, Song L, Wang Y, Ding X, Zeng J, Lehoux S, Aryal RP, Wang J, Crew VK, van Die I, Chapman AB, Cummings RD, Ju T. Epigenetic silencing of the chaperone Cosmc in human leukocytes expressing tn antigen. J Biol Chem 2012; 287:41523-33. [PMID: 23035125 DOI: 10.1074/jbc.m112.371989] [Citation(s) in RCA: 243] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cosmc is the specific molecular chaperone in the endoplasmic reticulum for T-synthase, a Golgi β3-galactosyltransferase that generates the core 1 O-glycan, Galβ1-3GalNAcα-Ser/Thr, in glycoproteins. Dysfunctional Cosmc results in the formation of inactive T-synthase and consequent expression of the Tn antigen (GalNAcα1-Ser/Thr), which is associated with several human diseases. However, the molecular regulation of expression of Cosmc, which is encoded by a single gene on Xq24, is poorly understood. Here we show that epigenetic silencing of Cosmc through hypermethylation of its promoter leads to loss of Cosmc transcripts in Tn4 cells, an immortalized B cell line from a male patient with a Tn-syndrome-like phenotype. These cells lack T-synthase activity and express the Tn antigen. Treatment of cells with 5-aza-2'-deoxycytidine causes restoration of Cosmc transcripts, restores T-synthase activity, and reduces Tn antigen expression. Bisulfite sequencing shows that CG dinucleotides in the Cosmc core promoter are hypermethylated. Interestingly, several other X-linked genes associated with glycosylation are not silenced in Tn4 cells, and we observed no correlation of a particular DNA methyltransferase to aberrant methylation of Cosmc in these cells. Thus, hypermethylation of the Cosmc promoter in Tn4 cells is relatively specific. Epigenetic silencing of Cosmc provides another mechanism underlying the abnormal expression of the Tn antigen, which may be important in understanding aberrant Tn antigen expression in human diseases, including IgA nephropathy and cancer.
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Affiliation(s)
- Rongjuan Mi
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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