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Radhakrishnan A, Chellapandian H, Ramasamy P, Jeyachandran S. Back2Basics: animal lectins: an insight into a highly versatile recognition protein. JOURNAL OF PROTEINS AND PROTEOMICS 2023; 14:43-59. [PMID: 36597476 PMCID: PMC9799708 DOI: 10.1007/s42485-022-00102-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/15/2022] [Accepted: 12/08/2022] [Indexed: 12/31/2022]
Abstract
The rapid advancement of molecular research has contributed to the discovery of 'Lectin', a carbohydrate-binding protein which specifically interacts with receptors on surface glycan moieties that regulate various critical cellular activities. The first animal lectin reported was 'the asialoglycoprotein receptor' in mammalian cells which helped analyze how animal lectins differ in glycoconjugate binding. Animal lectins are classified into several families, depending on their diverse cellular localization, and the binding specificities of their Carbohydrate-Recognition Domain (CRD) modules. Earlier characterization of animal lectins classified them into two structural families, the C-type (Ca2+-dependent binding) and S-type galectins (sulfhydryl-dependent binding) lectins. The C-type lectin includes the most significant animal lectins, such as endocytic receptors, mannose receptors, selectins, and collectins. The recent developments in research based on the complexity of the carbohydrate ligands, the metabolic processes they perform, their expression levels, and their reliance on divalent cations have identified more than 100 animal lectins and classified them into around 13 different families, such as Calnexin, F-lectin, Intelectin, Chitinase-like lectin, F-box lectin, etc. Understanding their structure and expression patterns have aided in defining their significant functions including cell adhesion, antimicrobial activity, innate immunity, disease diagnostic biomarkers, and drug delivery through specific carbohydrate-protein interactions. Such extensive potential roles of animal lectins made it equally important to plant lectins among researchers. Hence, the review focuses on providing an overview of animal lectins, their taxonomy, structural characteristics, and functions in diverse aspects interconnected to their specific carbohydrate and glycoconjugate binding. Graphical abstract
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Affiliation(s)
- Akshaya Radhakrishnan
- PG & Research Department of Biotechnology & Microbiology, National College, Tiruchirappalli, Tamil Nadu 620001 India
| | - Hethesh Chellapandian
- PG & Research Department of Biotechnology & Microbiology, National College, Tiruchirappalli, Tamil Nadu 620001 India
| | - Pasiyappazham Ramasamy
- Department of Physiology, Saveetha Dental College & Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, Tamil Nadu 600077 India
| | - Sivakamavalli Jeyachandran
- PG & Research Department of Biotechnology & Microbiology, National College, Tiruchirappalli, Tamil Nadu 620001 India
- Centre for Biotechnology & Biosignal Transduction, Department of Orthodontics, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, Tamil Nadu 600077 India
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Quach TD, Huang W, Sahu R, Diadhiou CM, Raparia C, Johnson R, Leung TM, Malkiel S, Ricketts PG, Gallucci S, Tükel Ç, Jacob CO, Lesser ML, Zou YR, Davidson A. Context dependent induction of autoimmunity by TNF signaling deficiency. JCI Insight 2022; 7:149094. [PMID: 35104241 PMCID: PMC8983147 DOI: 10.1172/jci.insight.149094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 01/26/2022] [Indexed: 11/17/2022] Open
Abstract
TNF inhibitors are widely used to treat inflammatory diseases; however, 30%–50% of treated patients develop new autoantibodies, and 0.5%–1% develop secondary autoimmune diseases, including lupus. TNF is required for formation of germinal centers (GCs), the site where high-affinity autoantibodies are often made. We found that TNF deficiency in Sle1 mice induced TH17 T cells and enhanced the production of germline encoded, T-dependent IgG anti-cardiolipin antibodies but did not induce GC formation or precipitate clinical disease. We then asked whether a second hit could restore GC formation or induce pathogenic autoimmunity in TNF-deficient mice. By using a range of immune stimuli, we found that somatically mutated autoantibodies and clinical disease can arise in the setting of TNF deficiency via extrafollicular pathways or via atypical GC-like pathways. This breach of tolerance may be due to defects in regulatory signals that modulate the negative selection of pathogenic autoreactive B cells.
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Affiliation(s)
- Tam D Quach
- Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Weiqing Huang
- Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Ranjit Sahu
- Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Catherine Mm Diadhiou
- Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Chirag Raparia
- Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Roshawn Johnson
- Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Tung Ming Leung
- Biostatistics Unit, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Susan Malkiel
- Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Peta-Gay Ricketts
- Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Stefania Gallucci
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, United States of America
| | - Çagla Tükel
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, United States of America
| | - Chaim O Jacob
- Department of Medicine, University of Southern California, Los Angeles, United States of America
| | - Martin L Lesser
- Biostatistics Unit, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Yong-Rui Zou
- Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Manhasset, United States of America
| | - Anne Davidson
- Institute of Molecular Medicine, Feinstein Institutes for Medical Research, Manhasset, United States of America
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Enterina JR, Jung J, Macauley MS. Coordinated roles for glycans in regulating the inhibitory function of CD22 on B cells. Biomed J 2019; 42:218-232. [PMID: 31627864 PMCID: PMC6818156 DOI: 10.1016/j.bj.2019.07.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/19/2019] [Accepted: 07/26/2019] [Indexed: 01/17/2023] Open
Abstract
CD22 is an inhibitory B cell co-receptor that recognizes sialic acid-containing glycoconjugates as ligands. Interactions with its glycan ligands are key to regulating the ability of CD22 to modulate B cell function, the most widely explored of which is antagonizing B cell receptor (BCR) signaling. Most importantly, interactions of CD22 with ligands on the same cell (cis) control the organization of CD22 on the cell surface, which minimizes co-localization with the BCR. In contrast with the modest ability of CD22 to intrinsically dampen BCR signaling, glycan ligands presented on another cell (trans) along with an antigen drawn CD22 and the BCR together within an immunological synapse, strongly inhibiting BCR signaling. New concepts are emerging for how CD22 controls B cell function, such as changes in glycosylation at different stages of B cell differentiation, specifically on GC B cells. Related to these changes, new players, such galectin-9, have been discovered that regulate cell surface nanoclusters of CD22. Roles of glycan ligands in controlling CD22 are the primary focus of this review as we highlight the ability of CD22 to modulate B cell function.
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Affiliation(s)
- Jhon R Enterina
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Canada
| | - Jaesoo Jung
- Department of Chemistry, University of Alberta, Edmonton, Canada
| | - Matthew S Macauley
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Canada; Department of Chemistry, University of Alberta, Edmonton, Canada.
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Leveraging Siglec-8 endocytic mechanisms to kill human eosinophils and malignant mast cells. J Allergy Clin Immunol 2017; 141:1774-1785.e7. [PMID: 28734845 DOI: 10.1016/j.jaci.2017.06.028] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 06/01/2017] [Accepted: 06/12/2017] [Indexed: 01/06/2023]
Abstract
BACKGROUND Sialic acid-binding immunoglobulin-like lectin (Siglec)-8 is a cell-surface protein expressed selectively on human eosinophils, mast cells, and basophils, making it an ideal target for the treatment of diseases involving these cell types. However, the effective delivery of therapeutic agents to these cells requires an understanding of the dynamics of Siglec-8 surface expression. OBJECTIVES We sought to determine whether Siglec-8 is endocytosed in human eosinophils and malignant mast cells, identify mechanisms underlying its endocytosis, and demonstrate whether a toxin can be targeted to Siglec-8-bearing cells to kill these cells. METHODS Siglec-8 surface dynamics were examined by flow cytometry using peripheral blood eosinophils, mast cell lines, and Siglec-8-transduced cells in the presence of inhibitors targeting components of endocytic pathways. Siglec-8 intracellular trafficking was followed by confocal microscopy. The ribosome-inhibiting protein saporin was conjugated to a Siglec-8-specific antibody to examine the targeting of an agent to these cells through Siglec-8 endocytosis. RESULTS Siglec-8 endocytosis required actin rearrangement, tyrosine kinase and protein kinase C activities, and both clathrin and lipid rafts. Internalized Siglec-8 localized to the lysosomal compartment. Maximal endocytosis in Siglec-8-transduced HEK293T cells required an intact immunoreceptor tyrosine-based inhibitory motif. Siglec-8 was also shuttled to the surface via a distinct pathway. Sialidase treatment of eosinophils revealed that Siglec-8 is partially masked by sialylated cis ligands. Targeting saporin to Siglec-8 consistently caused extensive cell death in eosinophils and the human mast cell leukemia cell line HMC-1.2. CONCLUSIONS Therapeutic payloads can be targeted selectively to eosinophils and malignant mast cells by exploiting this Siglec-8 endocytic pathway.
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Abstract
Many Siglecs function as inhibitory receptors on innate and adaptive immune cells and may contribute to the attenuation of immune responses to tumors. Siglec 9 on neutrophils and Siglec 7 on NK cells are prominent examples of inhibitory Siglecs that can potentially dampen anti-tumor immunity. CD169 is a Siglec that may function as an adhesion molecule and a facilitator of the recognition and internalization of sialic acid decorated apoptotic bodies and exosomes derived from tumors. It can potentially contribute to both the attenuation as well as the facilitation of anti-tumor immunity. Siglecs have been best studied in the tumor context in animal models of cancer. Modulators of Siglec function are likely to be developed and investigated clinically in a cancer context over the next few years.
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Affiliation(s)
- Isabella Fraschilla
- Ragon Institute of MGH, MIT and Harvard, Harvard Medical School, Cambridge, MA, USA
| | - Shiv Pillai
- Ragon Institute of MGH, MIT and Harvard, Harvard Medical School, Cambridge, MA, USA
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Abstract
An important underlying mechanism that contributes to autoimmunity is the loss of inhibitory signaling in the immune system. Sialic acid-recognizing Ig superfamily lectins or Siglecs are a family of cell surface proteins largely expressed in hematopoietic cells. The majority of Siglecs are inhibitory receptors expressed in immune cells that bind to sialic acid-containing ligands and recruit SH2-domain-containing tyrosine phosphatases to their cytoplasmic tails. They deliver inhibitory signals that can contribute to the constraining of immune cells, and thus protect the host from autoimmunity. The inhibitory functions of CD22/Siglec-2 and Siglec-G and their contributions to tolerance and autoimmunity, primarily in the B lymphocyte context, are considered in some detail in this review. The relevance to autoimmunity and unregulated inflammation of modified sialic acids, enzymes that modify sialic acid, and other sialic acid-binding proteins are also reviewed.
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Affiliation(s)
- Vinay S Mahajan
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA.,Departments of Medicine and Pathology, Harvard Medical School, Boston, MA, USA.,Deaprtment of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Shiv Pillai
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA.,Departments of Medicine and Pathology, Harvard Medical School, Boston, MA, USA
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Chang CH, Wang Y, Gupta P, Goldenberg DM. Extensive crosslinking of CD22 by epratuzumab triggers BCR signaling and caspase-dependent apoptosis in human lymphoma cells. MAbs 2015; 7:199-211. [PMID: 25484043 PMCID: PMC4622945 DOI: 10.4161/19420862.2014.979081] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epratuzumab has demonstrated therapeutic activity in patients with non-Hodgkin lymphoma, acute lymphoblastic leukemia, systemic lupus erythematosus, and Sjögren's syndrome, but its mechanism of affecting normal and malignant B cells remains incompletely understood. We reported previously that epratuzumab displayed in vitro cytotoxicity to CD22-expressing Burkitt lymphoma cell lines (Daudi and Ramos) only when immobilized on plates or combined with a crosslinking antibody plus a suboptimal amount of anti-IgM (1 μg/mL). Herein, we show that, in the absence of additional anti-IgM ligation, extensive crosslinking of CD22 by plate-immobilized epratuzumab induced intracellular changes in Daudi cells similar to ligating B-cell antigen receptor with a sufficiently high amount of anti-IgM (10 μg/mL). Specifically, either treatment led to phosphorylation of CD22, CD79a and CD79b, along with their translocation to lipid rafts, both of which were essential for effecting caspase-dependent apoptosis. Moreover, such immobilization induced stabilization of F-actin, phosphorylation of Lyn, ERKs and JNKs, generation of reactive oxygen species (ROS), decrease in mitochondria membrane potential (Δψm), upregulation of pro-apoptotic Bax, and downregulation of anti-apoptotic Bcl-xl and Mcl-1. The physiological relevance of immobilized epratuzumab was implicated by noting that several of its in vitro effects, including apoptosis, drop in Δψm, and generation of ROS, could be observed with soluble epratuzumab in Daudi cells co-cultivated with human umbilical vein endothelial cells. These results suggest that the in vivo mechanism of non-ligand-blocking epratuzumab may, in part, involve the unmasking of CD22 to facilitate the trans-interaction of B cells with vascular endothelium.
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Key Words
- 488-annexin V, Alexa Fluor 488-conjugated annexin V
- 7-AAD, 7-aminoactinomycin D, Syk, spleen tyrosine kinase
- Anti-IgM, F(ab’)2 fragment of affinity-purified goat anti-human IgM, Fc5μ fragment
- BCR
- BCR, B-cell antigen receptor
- BSA, bovine serum albumin
- CD22
- CM-H2DCF-DA, 2′,7′-dichlorodihydrofluorescein diacetate
- DNP, 2,4-dinitrophenyl
- EC, endothelial cells
- ERKs, extracellular signal-regulated kinases
- FBS, fetal bovine serum
- FITC-DNase I, fluorescein isothiocyanate-conjugated DNase I
- GAH, F(ab′)2 fragment of affinity-purified goat anti-human IgG Fcγ fragment-specific
- HUV-EC
- HUV-EC, human umbilical vein endothelial cells
- ITIM, immunoreceptor tyrosine-based inhibition motif
- JNKs, c-Jun N-terminal kinases
- JP, jasplakinolide
- LatB, latrunculin B
- Lyn, Lck/Yes novel tyrosine kinase
- MAP kinases, mitogen-activated protein kinases
- MTS, (3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium
- PARP, poly(ADP-ribose) polymerase
- PBS, phosphate-buffered saline
- PLCγ2, phospholipase C, isotype gamma 2
- ROS, reactive oxygen species
- Rhodamine-anti-IgG, rhodamine-conjugated F(ab′)2 fragment of affinity-purified goat anti-human IgG, F(ab′)2 fragment-specific
- TMRE/tetramethylrhodamine/ethyl ester
- epratuzumab
- human B-cell lymphoma
- immobilized
- mIgM, membrane IgM
- Δψm, mitochondria membrane potential
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Lee M, Kiefel H, LaJevic MD, Macauley MS, Kawashima H, O'Hara E, Pan J, Paulson JC, Butcher EC. Transcriptional programs of lymphoid tissue capillary and high endothelium reveal control mechanisms for lymphocyte homing. Nat Immunol 2014; 15:982-95. [PMID: 25173345 PMCID: PMC4222088 DOI: 10.1038/ni.2983] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 07/31/2014] [Indexed: 12/13/2022]
Abstract
Lymphocytes are recruited from blood by high-endothelial venules (HEVs). We performed transcriptomic analyses and identified molecular signatures that distinguish HEVs from capillary endothelium and that define tissue-specific HEV specialization. Capillaries expressed gene programs for vascular development. HEV-expressed genes showed enrichment for genes encoding molecules involved in immunological defense and lymphocyte migration. We identify capillary and HEV markers and candidate mechanisms for regulated recruitment of lymphocytes, including a lymph node HEV-selective transmembrane mucin; transcriptional control of functionally specialized carbohydrate ligands for lymphocyte L-selectin; HEV expression of molecules for transendothelial migration; and metabolic programs for lipid mediators of lymphocyte motility and chemotaxis. We also elucidate a carbohydrate-recognition pathway that targets B cells to intestinal lymphoid tissues, defining CD22 as a lectin-homing receptor for mucosal HEVs.
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Affiliation(s)
- Mike Lee
- Laboratory of Immunology and Vascular Biology, Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
| | - Helena Kiefel
- Laboratory of Immunology and Vascular Biology, Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
| | - Melissa D LaJevic
- Laboratory of Immunology and Vascular Biology, Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
| | - Matthew S Macauley
- Departments of Cell and Molecular Biology, Immunology and Microbial Science, and Chemical Physiology, The Scripps Research Institute, La Jolla, California USA
| | | | - Edward O'Hara
- Palo Alto Veterans Institute for Research, Palo Alto, California, USA
| | - Junliang Pan
- Palo Alto Veterans Institute for Research, Palo Alto, California, USA
| | - James C Paulson
- Departments of Cell and Molecular Biology, Immunology and Microbial Science, and Chemical Physiology, The Scripps Research Institute, La Jolla, California USA
| | - Eugene C Butcher
- 1] Laboratory of Immunology and Vascular Biology, Department of Pathology, Stanford University School of Medicine, Stanford, California, USA. [2] Palo Alto Veterans Institute for Research, Palo Alto, California, USA. [3] The Center for Molecular Biology and Medicine, Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
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Kitazume S, Imamaki R, Ogawa K, Taniguchi N. Sweet role of platelet endothelial cell adhesion molecule in understanding angiogenesis. Glycobiology 2014; 24:1260-4. [PMID: 25214153 DOI: 10.1093/glycob/cwu094] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The vascular endothelial glycocalyx contains several anionic sugars, one of which is a sialic acid attached to both N- and O-glycans. Platelet endothelial cell adhesion molecule (PECAM), a member of the Ig superfamily that plays multiple roles in cell adhesion, mechanical stress sensing, antiapoptosis and angiogenesis, has recently been shown to recognize α2,6-sialic acid. In endothelial cells that lack α2,6-sialic acid because of sialyltransferase ST6Gal I deficiency, impairment of the homophilic PECAM interaction and PECAM-dependent cell survival signaling is observed. In this review, we will introduce part of the biological role of PECAM, and discuss how the lectin activity of PECAM is related to angiogenesis.
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Affiliation(s)
- Shinobu Kitazume
- Disease Glycomics Team, Systems Glycobiology Research Group, Global Research Cluster, RIKEN-Max Planck Joint Research Center, RIKEN, Saitama 351-0198, Japan
| | - Rie Imamaki
- Disease Glycomics Team, Systems Glycobiology Research Group, Global Research Cluster, RIKEN-Max Planck Joint Research Center, RIKEN, Saitama 351-0198, Japan
| | - Kazuko Ogawa
- Disease Glycomics Team, Systems Glycobiology Research Group, Global Research Cluster, RIKEN-Max Planck Joint Research Center, RIKEN, Saitama 351-0198, Japan
| | - Naoyuki Taniguchi
- Disease Glycomics Team, Systems Glycobiology Research Group, Global Research Cluster, RIKEN-Max Planck Joint Research Center, RIKEN, Saitama 351-0198, Japan
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Kitazume S, Imamaki R, Kurimoto A, Ogawa K, Kato M, Yamaguchi Y, Tanaka K, Ishida H, Ando H, Kiso M, Hashii N, Kawasaki N, Taniguchi N. Interaction of platelet endothelial cell adhesion molecule (PECAM) with α2,6-sialylated glycan regulates its cell surface residency and anti-apoptotic role. J Biol Chem 2014; 289:27604-13. [PMID: 25135639 DOI: 10.1074/jbc.m114.563585] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The luminal sides of vascular endothelial cells are heavily covered with a so-called glycocalyx, but the precise role of the endothelial glycocalyx remains unclear. Our previous study showed that N-glycan α2,6-sialylation regulates the cell surface residency of an anti-apoptotic molecule, platelet endothelial cell adhesion molecule (PECAM), as well as the sensitivity of endothelial cells toward apoptotic stimuli. As PECAM itself was shown to be modified with biantennary N-glycans having α2,6-sialic acid, we expected that PECAM would possess lectin-like activity toward α2,6-sialic acid to ensure its homophilic interaction. To verify this, a series of oligosaccharides were initially added to observe their inhibitory effects on the homophilic PECAM interaction in vitro. We found that a longer α2,6-sialylated oligosaccharide exhibited strong inhibitory activity. Furthermore, we found that a cluster-type α2,6-sialyl N-glycan probe specifically bound to PECAM-immobilized beads. Moreover, the addition of the α2,6-sialylated oligosaccharide to endothelial cells enhanced the internalization of PECAM as well as the sensitivity to apoptotic stimuli. Collectively, these findings suggest that PECAM is a sialic acid binding lectin and that this binding property supports endothelial cell survival. Notably, our findings that α2,6-sialylated glycans influenced the susceptibility to endothelial cell apoptosis shed light on the possibility of using a glycan-based method to modulate angiogenesis.
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Affiliation(s)
| | | | | | | | - Masaki Kato
- Structural Glycobiology Team, RIKEN-Max Planck Joint Research Center, Global Research Cluster, and
| | - Yoshiki Yamaguchi
- Structural Glycobiology Team, RIKEN-Max Planck Joint Research Center, Global Research Cluster, and
| | - Katsunori Tanaka
- Biofunctional Synthetic Chemistry Laboratory, RIKEN, Saitama 351-0198, Japan
| | - Hideharu Ishida
- Department of Applied Bioorganic Chemistry, Gifu University, Gifu 501-1193, Japan
| | - Hiromune Ando
- Department of Applied Bioorganic Chemistry, Gifu University, Gifu 501-1193, Japan, Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan, and
| | - Makoto Kiso
- Department of Applied Bioorganic Chemistry, Gifu University, Gifu 501-1193, Japan, Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan, and
| | - Noritaka Hashii
- Division of Biological Chemistry and Biologicals, National Institute of Health Sciences, Tokyo 158-8501, Japan
| | - Nana Kawasaki
- Division of Biological Chemistry and Biologicals, National Institute of Health Sciences, Tokyo 158-8501, Japan
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Sensing the neuronal glycocalyx by glial sialic acid binding immunoglobulin-like lectins. Neuroscience 2014; 275:113-24. [PMID: 24924144 DOI: 10.1016/j.neuroscience.2014.05.061] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/30/2014] [Accepted: 05/30/2014] [Indexed: 11/22/2022]
Abstract
Sialic acid binding immunoglobulin-like lectins (Siglecs) are cell surface receptors of microglia and oligodendrocytes that recognize the sialic acid cap of healthy neurons and neighboring glial cells. Upon ligand binding, Siglecs typically signal through an immunoreceptor tyrosine-based inhibition motif (ITIM) to keep the cell in a homeostatic status and support healthy neighboring cells. Siglecs can be divided into two groups; the first, being conserved among different species. The conserved Siglec-4/myelin-associated glycoprotein is expressed on oligodendrocytes and Schwann cells. Siglec-4 protects neurons from acute toxicity via interaction with sialic acids bound to neuronal gangliosides. The second group of Siglecs, named CD33-related Siglecs, is almost exclusively expressed on immune cells and is highly variable among different species. Microglial expression of Siglec-11 is human lineage-specific and prevents neurotoxicity via interaction with α2.8-linked sialic acid oligomers exposed on the neuronal glycocalyx. Microglial Siglec-E is a mouse CD33-related Siglec member that prevents microglial phagocytosis and the associated oxidative burst. Mouse Siglec-E of microglia binds to α2.8- and α2.3-linked sialic acid residues of the healthy glycocalyx of neuronal and glial cells. Recently, polymorphisms of the human Siglec-3/CD33 were linked to late onset Alzheimer's disease by genome-wide association studies. Human Siglec-3 is expressed on microglia and produces inhibitory signaling that decreases uptake of particular molecules such as amyloid-β aggregates. Thus, glial ITIM-signaling Siglecs recognize the intact glycocalyx of neurons and are involved in the modulation of neuron-glia interaction in healthy and diseased brain.
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Lee C, Liu A, Miranda-Ribera A, Hyun SW, Lillehoj EP, Cross AS, Passaniti A, Grimm PR, Kim BY, Welling PA, Madri JA, DeLisser HM, Goldblum SE. NEU1 sialidase regulates the sialylation state of CD31 and disrupts CD31-driven capillary-like tube formation in human lung microvascular endothelia. J Biol Chem 2014; 289:9121-35. [PMID: 24550400 PMCID: PMC3979388 DOI: 10.1074/jbc.m114.555888] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Indexed: 12/20/2022] Open
Abstract
The highly sialylated vascular endothelial surface undergoes changes in sialylation upon adopting the migratory/angiogenic phenotype. We recently established endothelial cell (EC) expression of NEU1 sialidase (Cross, A. S., Hyun, S. W., Miranda-Ribera, A., Feng, C., Liu, A., Nguyen, C., Zhang, L., Luzina, I. G., Atamas, S. P., Twaddell, W. S., Guang, W., Lillehoj, E. P., Puché, A. C., Huang, W., Wang, L. X., Passaniti, A., and Goldblum, S. E. (2012) NEU1 and NEU3 sialidase activity expressed in human lung microvascular endothelia. NEU1 restrains endothelial cell migration whereas NEU3 does not. J. Biol. Chem. 287, 15966-15980). We asked whether NEU1 might regulate EC capillary-like tube formation on a Matrigel substrate. In human pulmonary microvascular ECs (HPMECs), prior silencing of NEU1 did not alter tube formation. Infection of HPMECs with increasing multiplicities of infection of an adenovirus encoding for catalytically active WT NEU1 dose-dependently impaired tube formation, whereas overexpression of either a catalytically dead NEU1 mutant, NEU1-G68V, or another human sialidase, NEU3, did not. NEU1 overexpression also diminished EC adhesion to the Matrigel substrate and restrained EC migration in a wounding assay. In HPMECs, the adhesion molecule, CD31, also known as platelet endothelial cell adhesion molecule-1, was sialylated via α2,6-linkages, as shown by Sambucus nigra agglutinin lectin blotting. NEU1 overexpression increased CD31 binding to Arachis hypogaea or peanut agglutinin lectin, indicating CD31 desialylation. In the postconfluent state, when CD31 ectodomains are homophilically engaged, NEU1 was recruited to and desialylated CD31. In postconfluent ECs, CD31 was desialylated compared with subconfluent cells, and prior NEU1 silencing completely protected against CD31 desialylation. Prior CD31 silencing and the use of CD31-null ECs each abrogated the NEU1 inhibitory effect on EC tube formation. Sialyltransferase 6 GAL-I overexpression increased α2,6-linked CD31 sialylation and dose-dependently counteracted NEU1-mediated inhibition of EC tube formation. These combined data indicate that catalytically active NEU1 inhibits in vitro angiogenesis through desialylation of its substrate, CD31.
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Affiliation(s)
| | | | | | | | | | - Alan S. Cross
- From the Departments of Medicine
- the Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Antonino Passaniti
- Pathology, and
- the Department of Veterans Affairs, Baltimore, Maryland 21201
| | | | | | | | - Joseph A. Madri
- the Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520, and
| | - Horace M. DeLisser
- the Pulmonary, Allergy, and Critical Care Division, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Simeon E. Goldblum
- From the Departments of Medicine
- Pathology, and
- the Department of Veterans Affairs, Baltimore, Maryland 21201
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13
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Ogata S, Shimizu C, Franco A, Touma R, Kanegaye JT, Choudhury BP, Naidu NN, Kanda Y, Hoang LT, Hibberd ML, Tremoulet AH, Varki A, Burns JC. Treatment response in Kawasaki disease is associated with sialylation levels of endogenous but not therapeutic intravenous immunoglobulin G. PLoS One 2013; 8:e81448. [PMID: 24324693 PMCID: PMC3855660 DOI: 10.1371/journal.pone.0081448] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 10/12/2013] [Indexed: 12/12/2022] Open
Abstract
Objectives Although intravenous immunoglobulin (IVIG) is highly effective in Kawasaki disease (KD), mechanisms are not understood and 10-20% of patients are treatment-resistant, manifesting a higher rate of coronary artery aneurysms. Murine models suggest that α2-6-linked sialic acid (α2-6Sia) content of IVIG is critical for suppressing inflammation. However, pro-inflammatory states also up-regulate endogenous levels of β-galactoside:α2-6 sialyltransferase-I (ST6Gal-I), the enzyme that catalyzes addition of α2-6Sias to N-glycans. We asked whether IVIG failures correlated with levels of α2-6Sia on infused IVIG or on the patient’s own endogenous IgG. Methods We quantified levels of α2-6Sia in infused IVIG and endogenous IgG from 10 IVIG-responsive and 10 resistant KD subjects using multiple approaches. Transcript levels of ST6GAL1, in patient whole blood and B cell lines were evaluated by RT-PCR. Plasma soluble (s)ST6Gal-I levels were measured by ELISA. Results There was no consistent difference in median sialylation levels of infused IVIG between groups. However, α2-6Sia levels in endogenous IgG, ST6GAL1 transcript levels, and ST6Gal-I protein in serum from IVIG-resistant KD subjects were lower than in responsive subjects at both pre-treatment and one-year time points (p <0.001, respectively). Conclusions Our data indicate sialylation levels of therapeutic IVIG are unrelated to treatment response in KD. Rather, lower sialylation of endogenous IgG and lower blood levels of ST6GALI mRNA and ST6Gal-I enzyme predict therapy resistance. These differences were stable over time, suggesting a genetic basis. Because IVIG-resistance increases risk of coronary artery aneurysms, our findings have important implications for the identification and treatment of such individuals.
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Affiliation(s)
- Shohei Ogata
- Department of Pediatrics, University of California San Diego, School of Medicine, La Jolla, California, United States of America
| | - Chisato Shimizu
- Department of Pediatrics, University of California San Diego, School of Medicine, La Jolla, California, United States of America
| | - Alessandra Franco
- Department of Pediatrics, University of California San Diego, School of Medicine, La Jolla, California, United States of America
| | - Ranim Touma
- Department of Pediatrics, University of California San Diego, School of Medicine, La Jolla, California, United States of America
| | - John T. Kanegaye
- Department of Pediatrics, University of California San Diego, School of Medicine, La Jolla, California, United States of America
- Rady Children’s Hospital San Diego, San Diego, California, United States of America
| | - Biswa P. Choudhury
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of San Diego, School of Medicine, La Jolla, California, United States of America
| | - Natasha N. Naidu
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of San Diego, School of Medicine, La Jolla, California, United States of America
| | - Yutaka Kanda
- Kyowa Hakko Kirin California, Inc., La Jolla, California, United States of America
| | - Long T. Hoang
- Division of Infectious Disease 1, Genome Institute of Singapore, Singapore, Singapore
| | - Martin L. Hibberd
- Division of Human Genetics, Genome Institute of Singapore, Singapore, Singapore
| | - Adriana H. Tremoulet
- Department of Pediatrics, University of California San Diego, School of Medicine, La Jolla, California, United States of America
- Rady Children’s Hospital San Diego, San Diego, California, United States of America
| | - Ajit Varki
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of San Diego, School of Medicine, La Jolla, California, United States of America
| | - Jane C. Burns
- Department of Pediatrics, University of California San Diego, School of Medicine, La Jolla, California, United States of America
- Rady Children’s Hospital San Diego, San Diego, California, United States of America
- * E-mail:
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14
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Chaze T, Slomianny MC, Milliat F, Tarlet G, Lefebvre-Darroman T, Gourmelon P, Bey E, Benderitter M, Michalski JC, Guipaud O. Alteration of the serum N-glycome of mice locally exposed to high doses of ionizing radiation. Mol Cell Proteomics 2012; 12:283-301. [PMID: 23146835 DOI: 10.1074/mcp.m111.014639] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Exposure of the skin to ionizing radiation leads to characteristic reactions that will often turn into a pathophysiological process called the cutaneous radiation syndrome. The study of this disorder is crucial to finding diagnostic and prognostic bioindicators of local radiation exposure or radiation effects. It is known that irradiation alters the serum proteome content and potentially post-translationally modifies serum proteins. In this study, we investigated whether localized irradiation of the skin alters the serum glycome. Two-dimensional differential in-gel electrophoresis of serum proteins from a man and from mice exposed to ionizing radiation showed that potential post-translational modification changes occurred following irradiation. Using a large-scale quantitative mass-spectrometry-based glycomic approach, we performed a global analysis of glycan structures of serum proteins from non-irradiated and locally irradiated mice exposed to high doses of γ-rays (20, 40, and 80 Gy). Non-supervised descriptive statistical analyses (principal component analysis) using quantitative glycan structure data allowed us to discriminate between uninjured/slightly injured animals and animals that developed severe lesions. Decisional statistics showed that several glycan families were down-regulated whereas others increased, and that particular structures were statistically significantly changed in the serum of locally irradiated mice. The observed increases in multiantennary N-glycans and in outer branch fucosylation and sialylation were associated with the up-regulation of genes involved in glycosylation in the liver, which is the main producer of serum proteins, and with an increase in the key proinflammatory serum cytokines IL-1β, IL-6, and TNFα, which can regulate the expression of glycosylation genes. Our results suggest for the first time a role of serum protein glycosylation in response to irradiation. These protein-associated glycan structure changes might signal radiation exposure or effects.
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Affiliation(s)
- Thibault Chaze
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), DRPH, SRBE, LRTE, 92260 Fontenay-aux-Roses, France
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15
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Tuscano JM, Kato J, Pearson D, Xiong C, Newell L, Ma Y, Gandara DR, O'Donnell RT. CD22 antigen is broadly expressed on lung cancer cells and is a target for antibody-based therapy. Cancer Res 2012; 72:5556-65. [PMID: 22986740 DOI: 10.1158/0008-5472.can-12-0173] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Most patients with lung cancer still die from their disease, necessitating additional options to improve treatment. Here, we provide evidence for targeting CD22, a cell adhesion protein known to influence B-cell survival that we found is also widely expressed in lung cancer cells. In characterizing the antitumor activity of an established anti-CD22 monoclonal antibody (mAb), HB22.7, we showed CD22 expression by multiple approaches in various lung cancer subtypes, including 7 of 8 cell lines and a panel of primary patient specimens. HB22.7 displayed in vitro and in vivo cytotoxicity against CD22-positive human lung cancer cells and tumor xenografts. In a model of metastatic lung cancer, HB22.7 inhibited the development of pulmonary metastasis and extended overall survival. The finding that CD22 is expressed on lung cancer cells is significant in revealing a heretofore unknown mechanism of tumorigenesis and metastasis. Our work suggests that anti-CD22 mAbs may be useful for targeted therapy of lung cancer, a malignancy that has few tumor-specific targets.
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Affiliation(s)
- Joseph M Tuscano
- Division of Hematology and Oncology, Department of Internal Medicine, University of California Davis Comprehensive Cancer Center, Sacramento, CA 95817, USA.
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16
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Gieseke F, Mang P, Viebahn S, Sonntag I, Kruchen A, Erbacher A, Pfeiffer M, Handgretinger R, Müller I. Siglec-7 tetramers characterize B-cell subpopulations and leukemic blasts. Eur J Immunol 2012; 42:2176-86. [PMID: 22585296 DOI: 10.1002/eji.201142298] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 03/29/2012] [Accepted: 04/20/2012] [Indexed: 01/31/2023]
Abstract
Cell surface glycosylation has important regulatory functions in the maturation, activation, and homeostasis of lymphocytes. The family of human sialic acid-binding immunoglobulin-like lectins (siglecs) comprises inhibitory as well as activating receptors intimately involved in the regulation of immune responses. Analyses of the interaction between siglecs and glycans are hampered by the low affinity of this interaction. Therefore, we expressed siglec-7 in eukaryotic cells, allowing for glycosylation, and oligomerized the protein in analogy to MHC tetramers. Using this tool, flow cytometric analysis of lymphocytes became possible. Sialic acid-dependent binding of siglec-7 tetramers was confirmed by glycan array analysis and loss of siglec tetramer binding after neuraminidase treatment of lymphocytes. In contrast to most lymphocyte subpopulations, which showed high siglec-7 ligand expression, B-cell subpopulations could be further subdivided according to different siglec-7 ligand expression levels. We also analyzed blasts from acute lymphoblastic leukemias of the B-cell lineage as well as the T-cell lineage, since malignant transformation is often associated with aberrant cell surface glycosylation. While pediatric T-ALL blasts highly expressed siglec-7 ligands, siglec-7 ligands were barely detectable on cALL blasts. Taken together, oligomerization of recombinant soluble siglec-7 enabled flow cytometric identification of physiologic lymphocyte subpopulations and malignant blasts.
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17
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Cross AS, Hyun SW, Miranda-Ribera A, Feng C, Liu A, Nguyen C, Zhang L, Luzina IG, Atamas SP, Twaddell WS, Guang W, Lillehoj EP, Puché AC, Huang W, Wang LX, Passaniti A, Goldblum SE. NEU1 and NEU3 sialidase activity expressed in human lung microvascular endothelia: NEU1 restrains endothelial cell migration, whereas NEU3 does not. J Biol Chem 2012; 287:15966-80. [PMID: 22403397 DOI: 10.1074/jbc.m112.346817] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The microvascular endothelial surface expresses multiple molecules whose sialylation state regulates multiple aspects of endothelial function. To better regulate these sialoproteins, we asked whether endothelial cells (ECs) might express one or more catalytically active sialidases. Human lung microvascular EC lysates contained heat-labile sialidase activity for a fluorogenic substrate, 2'-(4-methylumbelliferyl)-α-D-N-acetylneuraminic acid (4-MU-NANA), that was dose-dependently inhibited by the competitive sialidase inhibitor, 2,3-dehydro-2-deoxy-N-acetylneuraminic acid but not its negative control. The EC lysates also contained sialidase activity for a ganglioside mixture. Using real time RT-PCR to detect mRNAs for the four known mammalian sialidases, NEU1, -2, -3, and -4, NEU1 mRNA was expressed at levels 2700-fold higher that those found for NEU2, -3, or -4. Western analyses indicated NEU1 and -3 protein expression. Using confocal microscopy and flow cytometry, NEU1 was immunolocalized to both the plasma membrane and the perinuclear region. NEU3 was detected both in the cytosol and nucleus. Prior siRNA-mediated knockdown of NEU1 and NEU3 each decreased EC sialidase activity for 4-MU-NANA by >65 and >17%, respectively, and for the ganglioside mixture by 0 and 40%, respectively. NEU1 overexpression in ECs reduced their migration into a wound by >40%, whereas NEU3 overexpression did not. Immunohistochemical studies of normal human tissues immunolocalized NEU1 and NEU3 proteins to both pulmonary and extrapulmonary vascular endothelia. These combined data indicate that human lung microvascular ECs as well as other endothelia express catalytically active NEU1 and NEU3. NEU1 restrains EC migration, whereas NEU3 does not.
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Affiliation(s)
- Alan S Cross
- Center for Vaccine Development, University of Maryland, School of Medicine, Baltimore, Maryland 21201, USA
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18
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Andrade CA, Oliveira MD, de Melo CP, Coelho LC, Correia MT, Nogueira ML, Singh PR, Zeng X. Diagnosis of dengue infection using a modified gold electrode with hybrid organic–inorganic nanocomposite and Bauhinia monandra lectin. J Colloid Interface Sci 2011; 362:517-23. [DOI: 10.1016/j.jcis.2011.07.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 07/01/2011] [Accepted: 07/02/2011] [Indexed: 11/29/2022]
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19
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Kannagi R, Ohmori K, Chen GY, Miyazaki K, Izawa M, Sakuma K. Sialylated and Sulfated Carbohydrate Ligands for Selectins and Siglecs: Involvement in Traffic and Homing of Human Memory T and B Lymphocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 705:549-69. [DOI: 10.1007/978-1-4419-7877-6_29] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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20
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Kitazume S, Imamaki R, Ogawa K, Komi Y, Futakawa S, Kojima S, Hashimoto Y, Marth JD, Paulson JC, Taniguchi N. Alpha2,6-sialic acid on platelet endothelial cell adhesion molecule (PECAM) regulates its homophilic interactions and downstream antiapoptotic signaling. J Biol Chem 2010; 285:6515-21. [PMID: 20048157 PMCID: PMC2825447 DOI: 10.1074/jbc.m109.073106] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Antiangiogenesis therapies are now part of the standard repertoire of cancer therapies, but the mechanisms for the proliferation and survival of endothelial cells are not fully understood. Although endothelial cells are covered with a glycocalyx, little is known about how endothelial glycosylation regulates endothelial functions. Here, we show that alpha2,6-sialic acid is necessary for the cell-surface residency of platelet endothelial cell adhesion molecule (PECAM), a member of the immunoglobulin superfamily that plays multiple roles in cell adhesion, mechanical stress sensing, antiapoptosis, and angiogenesis. As a possible underlying mechanism, we found that the homophilic interactions of PECAM in endothelial cells were dependent on alpha2,6-sialic acid. We also found that the absence of alpha2,6-sialic acid down-regulated the tyrosine phosphorylation of PECAM and recruitment of Src homology 2 domain-containing protein-tyrosine phosphatase 2 and rendered the cells more prone to mitochondrion-dependent apoptosis, as evaluated using PECAM- deficient endothelial cells. The present findings open up a new possibility that modulation of glycosylation could be one of the promising strategies for regulating angiogenesis.
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Affiliation(s)
- Shinobu Kitazume
- Disease Glycomics Team, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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21
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Duong BH, Tian H, Ota T, Completo G, Han S, Vela JL, Ota M, Kubitz M, Bovin N, Paulson JC, Paulson J, Nemazee D. Decoration of T-independent antigen with ligands for CD22 and Siglec-G can suppress immunity and induce B cell tolerance in vivo. ACTA ACUST UNITED AC 2009; 207:173-87. [PMID: 20038598 PMCID: PMC2812539 DOI: 10.1084/jem.20091873] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Autoreactive B lymphocytes first encountering self-antigens in peripheral tissues are normally regulated by induction of anergy or apoptosis. According to the “two-signal” model, antigen recognition alone should render B cells tolerant unless T cell help or inflammatory signals such as lipopolysaccharide are provided. However, no such signals seem necessary for responses to T-independent type 2 (TI-2) antigens, which are multimeric antigens lacking T cell epitopes and Toll-like receptor ligands. How then do mature B cells avoid making a TI-2–like response to multimeric self-antigens? We present evidence that TI-2 antigens decorated with ligands of inhibitory sialic acid–binding Ig-like lectins (siglecs) are poorly immunogenic and can induce tolerance to subsequent challenge with immunogenic antigen. Two siglecs, CD22 and Siglec-G, contributed to tolerance induction, preventing plasma cell differentiation or survival. Although mutations in CD22 and its signaling machinery have been associated with dysregulated B cell development and autoantibody production, previous analyses failed to identify a tolerance defect in antigen-specific mutant B cells. Our results support a role for siglecs in B cell self-/nonself-discrimination, namely suppressing responses to self-associated antigens while permitting rapid “missing self”–responses to unsialylated multimeric antigens. The results suggest use of siglec ligand antigen constructs as an approach for inducing tolerance.
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Affiliation(s)
- Bao Hoa Duong
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA
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22
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23
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Abstract
CD22 is an inhibitory coreceptor of the B-cell receptor (BCR), and plays a critical role in establishing signalling thresholds for B-cell activation. Like other coreceptors, the ability of CD22 to modulate B-cell signalling is critically dependent upon its proximity to the BCR, and this in turn is governed by the binding of its extracellular domain to alpha2,6-linked sialic acid ligands. Manipulation of CD22 ligand binding in various experimental settings has profound effects on B-cell signalling, but as yet there is no complete model for how ligand binding in vivo controls normal CD22 function. Several elegant studies have recently shed light on this issue, although the results appear to suggest two mutually exclusive models for the role of ligand binding; in either promoting or inhibiting, CD22 function. We shall therefore discuss these results in detail, and suggest possible approaches by which these conflicting experimental findings might be reconciled. We shall also consider a second important issue in CD22 biology, which relates to the role that defects in this receptor might play in mediating autoimmune disease. We review the current evidence for this, and discuss the importance of genetic background in modifying CD22 function and predisposition to autoimmunity.
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Affiliation(s)
- Jennifer A Walker
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Cambridge CB2 0XY, United Kingdom.
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24
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Kimura N, Ohmori K, Miyazaki K, Izawa M, Matsuzaki Y, Yasuda Y, Takematsu H, Kozutsumi Y, Moriyama A, Kannagi R. Human B-lymphocytes express alpha2-6-sialylated 6-sulfo-N-acetyllactosamine serving as a preferred ligand for CD22/Siglec-2. J Biol Chem 2007; 282:32200-7. [PMID: 17728258 DOI: 10.1074/jbc.m702341200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
CD22/Siglec-2, an important inhibitory co-receptor on B-lymphocytes, is known to recognize alpha2-6-sialylated glycan as a specific ligand. Here we propose that the alpha2-6-sialylated and 6-GlcNAc-sulfated determinant serves as a preferred ligand for CD22 because the binding of a human B-cell line to CD22 was almost completely abrogated after incubating the cells with NaClO3, an inhibitor of cellular sulfate metabolism, and was also significantly inhibited by a newly generated monoclonal antibody specific to the alpha2-6-sialylated 6-sulfo-N-acetyllactosamine (LacNAc) determinant (KN343, murine IgM). The alpha2-6-sialylated 6-sulfo-LacNAc determinant defined by the antibody was significantly expressed on a majority of normal human peripheral B-lymphocytes as well as follicular B-lymphocytes in peripheral lymph nodes. The determinant was also expressed in endothelial cells of high endothelial venules of secondary lymphoid tissues, including lymph nodes, tonsils, and intestine-associated lymphoid tissues, more strongly than on B-lymphocytes, suggesting a role for CD22 in B-cell interaction with blood vessels and trafficking. These results indicate that the alpha2-6-sialylated 6-sulfo-LacNAc determinant serves as an endogenous ligand for human CD22 and suggest the possibility that 6-GlcNAc sulfation as well as alpha2-6-sialylation may regulate CD22/Siglec-2 functions in humans.
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Affiliation(s)
- Naoko Kimura
- Department of Molecular Pathology, Aichi Cancer Center Research Institute, Nagoya 464-8681, Japan
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25
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Crocker PR, Paulson JC, Varki A. Siglecs and their roles in the immune system. Nat Rev Immunol 2007; 7:255-66. [PMID: 17380156 DOI: 10.1038/nri2056] [Citation(s) in RCA: 1460] [Impact Index Per Article: 85.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell surfaces in the immune system are richly equipped with a complex mixture of glycans, which can be recognized by diverse glycan-binding proteins. The Siglecs are a family of sialic-acid-binding immunoglobulin-like lectins that are thought to promote cell-cell interactions and regulate the functions of cells in the innate and adaptive immune systems through glycan recognition. In this Review, we describe recent studies on signalling mechanisms and discuss the potential role of Siglecs in triggering endocytosis and in pathogen recognition. Finally, we discuss the postulated functions of the recently discovered CD33-related Siglecs and consider the factors that seem to be driving their rapid evolution.
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Affiliation(s)
- Paul R Crocker
- Wellcome Trust Biocentre, College of Life Sciences, University of Dundee, Dundee DD 15EH, UK.
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26
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Ghosh S, Bandulet C, Nitschke L. Regulation of B cell development and B cell signalling by CD22 and its ligands alpha2,6-linked sialic acids. Int Immunol 2006; 18:603-11. [PMID: 16497829 DOI: 10.1093/intimm/dxh402] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
CD22 is an inhibitory co-receptor of B cell receptor (BCR)-mediated signalling which binds specifically to glycan ligands containing alpha2,6-linked sialic acids. This interaction modulates the CD22 activity by an unknown mechanism. Mice deficient for ST6GalI, the enzyme that generates alpha2,6-linked sialic acids, show an immunodeficient and opposing phenotype to CD22-deficient mice. By generating mice double-deficient for this receptor/ligand pair, we analysed its influence on B cell maturation and signalling. Both ST6GalI-deficient and ST6GalI x CD22-deficient mice showed normal B cell development, but an impaired marginal zone B cell population in the spleen. Both types of mutant mice also showed a reduced population of bone marrow recirculating B cells, a defect previously detected in CD22-/- mice. In adoptive transfer experiments, a migration defect of wild-type B cells to the bone marrow of ST6GalI-deficient mice was found. This suggests a direct involvement of CD22 and its ligands 2,6Sia in a homing process of recirculating B cells to the bone marrow. Interestingly, defective B cell Ca2+ signalling and proliferation of ST6Gal-/- mice was rescued in ST6GalI x CD22-deficient mice. This points to a new mechanism of BCR signal regulation by CD22 and its ligand.
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Affiliation(s)
- Snigdha Ghosh
- Department of Genetics, University of Erlangen, Erlangen, Germany
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27
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Wattel S, Mircescu H, Venet D, Burniat A, Franc B, Frank S, Andry G, Van Sande J, Rocmans P, Dumont JE, Detours V, Maenhaut C. Gene expression in thyroid autonomous adenomas provides insight into their physiopathology. Oncogene 2006; 24:6902-16. [PMID: 16027733 DOI: 10.1038/sj.onc.1208849] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of this study was to use the microarray technology to define expression profiles characteristic of thyroid autonomous adenomas and relate these findings to physiological mechanisms. Experiments were performed on a series of separated adenomas and their normal counterparts on Micromax cDNA microarrays covering 2400 genes (analysis I), and on a pool of adenomatous tissues and their corresponding normal counterparts using microarrays of 18,000 spots (analysis II). Results for genes present on the two arrays corroborated and several gene regulations previously determined by Northern blotting or microarrays in similar lesions were confirmed. Five overexpressed and 24 underexpressed genes were also confirmed by real-time RT-PCR in some of the samples used for microarray analysis, and in additional tumor specimens. Our results show: (1) a change in the cell populations of the tumor, with a marked decrease in lymphocytes and blood cells and an increase in endothelial cells. The latter increase would correspond to the establishment of a close relation between thyrocytes and endothelial cells and is related to increased N-cadherin expression. It explains the increased blood flow in the tumor; (2) a homogeneity of tumor samples correlating with their common physiopathological mechanism: the constitutive activation of the thyrotropin (TSH)/cAMP cascade; (3) a low proportion of regulated genes consistent with the concept of a minimal deviation tumor; (4) a higher expression of genes coding for specific functional proteins, consistent with the functional hyperactivity of the tumors; (5) an increase of phosphodiesterase gene expression which explains the relatively low cyclic AMP levels measured in these tumors; (6) an overexpression of antiapoptotic genes and underexpression of proapoptotic genes compatible with their low apoptosis rate; (7) an overexpression of N-cadherin and downregulation of caveolins, which casts doubt about the use of these expressions as markers for malignancy.
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Affiliation(s)
- Sandrine Wattel
- Institute of Interdisciplinary Research, School of Medicine, Free University of Brussels, Brussels, Belgium
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28
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García-Vallejo JJ, Van Dijk W, Van Het Hof B, Van Die I, Engelse MA, Van Hinsbergh VWM, Gringhuis SI. Activation of human endothelial cells by tumor necrosis factor-α results in profound changes in the expression of glycosylation-related genes. J Cell Physiol 2005; 206:203-10. [PMID: 16080149 DOI: 10.1002/jcp.20458] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The endothelium plays a central role in the logistics of the immune system by allowing the selective transmigration of leukocytes, as well as the maintenance of the circulation and coagulation homeostasis. Evidence is increasing that the carbohydrate composition of the endothelial cell surface is critical for the cells to exert their physiological function. The major aim of this study is to unravel the mechanisms underlying the expression of carbohydrate structures by endothelial cells, which are involved in leukocyte adhesion and migration. Using quantitative real-time PCR, the expression profile of a selected group of 74 glycosylation-related genes has been determined in human umbilical vein endothelial cells (HUVEC) and human foreskin microvascular endothelial cells (FMVEC) under control and TNFalpha-induced conditions. The set of genes comprised 59 glycosyltransferases, 6 mannosidases and 9 sulfotransferases. In parallel, the overall cell surface glycan profile has been assessed by the use of glycan-specific lectins and monoclonal antibodies. The results demonstrate that HUVEC and FMVEC differ substantially in the expression of glycosylation-related genes and, accordingly, also in the presence of different glycan epitopes on the cell membrane. Induction of an inflamed phenotype of the cells by treatment with TNFalpha differentially modulates a set of these genes in HUVEC and FMVEC resulting in a change in the cell membrane associated glycans that are of importance in inflammation-related endothelial cell-surface processes.
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Affiliation(s)
- Juan J García-Vallejo
- Department of Molecular Cell Biology & Immunology, VU Medical Center, Amsterdam, The Netherlands.
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29
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Abstract
Animal glycan-recognizing proteins can be broadly classified into two groups-lectins (which typically contain an evolutionarily conserved carbohydrate-recognition domain [CRD]) and sulfated glycosaminoglycan (SGAG)-binding proteins (which appear to have evolved by convergent evolution). Proteins other than antibodies and T-cell receptors that mediate glycan recognition via immunoglobulin (Ig)-like domains are called "I-type lectins." The major homologous subfamily of I-type lectins with sialic acid (Sia)-binding properties and characteristic amino-terminal structural features are called the "Siglecs" (Sia-recognizing Ig-superfamily lectins). The Siglecs can be divided into two groups: an evolutionarily conserved subgroup (Siglecs-1, -2, and -4) and a CD33/Siglec-3-related subgroup (Siglecs-3 and -5-13 in primates), which appear to be rapidly evolving. This article provides an overview of historical and current information about the Siglecs.
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Affiliation(s)
- Ajit Varki
- Research Center for Glycoscience, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan.
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30
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García-Vallejo JJ, van Dijk W, van Die I, Gringhuis SI. Tumor necrosis factor-alpha up-regulates the expression of beta1,4-galactosyltransferase I in primary human endothelial cells by mRNA stabilization. J Biol Chem 2005; 280:12676-82. [PMID: 15668241 DOI: 10.1074/jbc.m410093200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
During the course of an inflammatory response, the pro-inflammatory cytokine tumor necrosis factor-alpha (TNFalpha) triggers endothelial cells to increase the expression levels of adhesion molecules that are pivotal for the rolling, adhesion, and transmigration of leukocytes over the endothelial cell wall. Here we show that TNFalpha, in addition, has a regulatory function in the biosynthesis of proper carbohydrate molecules on endothelial cells that constitute ligands for adhesion molecules on leukocytes. Our data show that TNFalpha induced an increase in the expression of beta1,4-galactosyltransferase-1 (beta4GalT-1) in primary human umbilical vein endothelial cells in a time- and concentration-dependent manner. The beta4GalT-1 mRNA up-regulation correlated with an increase in the Golgi expression and catalytic activity of the enzyme. Furthermore, an enhanced incorporation of galactose was observed in newly synthesized glycoproteins. Analysis of the molecular mechanism behind the up-regulation of beta4GalT-1 showed that the increase in mRNA levels is due to an enhanced stability of the transcripts. These data strongly demonstrate that TNFalpha modulates the glycosylation of endothelial cells by a mechanism that directly enhances the stability of beta4GalT-1 mRNA transcripts.
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Affiliation(s)
- Juan Jesús García-Vallejo
- Department of Molecular Cell Biology and Immunology, Vrije Universiteit Medical Centre, 1007 MB Amsterdam, The Netherlands.
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31
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Nitschke L, Tsubata T. Molecular interactions regulate BCR signal inhibition by CD22 and CD72. Trends Immunol 2004; 25:543-50. [DOI: 10.1016/j.it.2004.08.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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32
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Blixt O, Collins BE, van den Nieuwenhof IM, Crocker PR, Paulson JC. Sialoside specificity of the siglec family assessed using novel multivalent probes: identification of potent inhibitors of myelin-associated glycoprotein. J Biol Chem 2003; 278:31007-19. [PMID: 12773526 DOI: 10.1074/jbc.m304331200] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Ten of the 11 known human siglecs or their murine orthologs have been evaluated for their specificity for over 25 synthetic sialosides representing most of the major sequences terminating carbohydrate groups of glycoproteins and glycolipids. Analysis has been performed using a novel multivalent platform comprising biotinylated sialosides bound to a streptavidin-alkaline phosphatase conjugate. Each siglec was found to have a unique specificity for binding 16 different sialoside-streptavidin-alkaline phosphatase probes. The relative affinities of monovalent sialosides were assessed for each siglec in competitive inhibition studies. The quantitative data obtained allows a detailed analysis of each siglec for the relative importance of sialic acid and the penultimate oligosaccharide sequence on binding affinity and specificity. Most remarkable was the finding that myelin-associated glycoprotein (Siglec-4) binds with 500-10,000-fold higher affinity to a series of mono- and di-sialylated derivatives of the O-linked T-antigen (Galbeta(1-3)-GalNAc(alpha)OThr) as compared with alpha-methyl-NeuAc.
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MESH Headings
- Alkaline Phosphatase
- Animals
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/metabolism
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/metabolism
- CHO Cells
- Carbohydrate Sequence
- Cell Adhesion Molecules
- Chimera
- Cricetinae
- Enzyme-Linked Immunosorbent Assay
- Galactosides/chemical synthesis
- Galactosides/metabolism
- Glycolipids/chemical synthesis
- Glycolipids/metabolism
- Glycoproteins/chemical synthesis
- Glycoproteins/metabolism
- Humans
- Lectins/genetics
- Lectins/metabolism
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Mice
- Molecular Sequence Data
- N-Acetylneuraminic Acid/metabolism
- Protein Binding
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Sialic Acid Binding Ig-like Lectin 1
- Sialic Acid Binding Ig-like Lectin 2
- Sialic Acid Binding Immunoglobulin-like Lectins
- Streptavidin
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Affiliation(s)
- Ola Blixt
- Scripps Research Institute, Department of Molecular Biology, La Jolla, California 92037, USA
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33
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Brinkman-Van der Linden EC, Varki A. Probing for Masked and Unmasked Siglecs on Cell Surfaces. Methods Enzymol 2003; 363:113-20. [PMID: 14579571 DOI: 10.1016/s0076-6879(03)01047-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Els C Brinkman-Van der Linden
- Departments of Medicine and Cellular Molecular Medicine, University of California-San Diego, School of Medicine, La Jolla, California 92093, USA
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34
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Khodair AI, Schmidt RR. Synthesis of C-glycosyl compounds of N-acetylneuraminic acid from D-gluconolactone. Carbohydr Res 2002; 337:1967-78. [PMID: 12433462 DOI: 10.1016/s0008-6215(02)00176-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A general strategy towards the synthesis of C-glycosyl compounds of N-acetylneuraminic acid (Neu5Ac) has been developed and successfully applied to the synthesis of C-methyl and C-phenyl derivatives. The key strategic elements are (i) chain extension of a D-gluconolactone derivative as C(6)-precursor with an allyl Grignard reagent as C(3)-precursor having in 2 position the C-linked aglycon moiety, (ii) stereoselective C-4/C-5 erythro-diol formation, (iii) 6-exo-trig selective heterocyclization, and (iv) installment of the 5-acetylamino and C-1 carboxylate functionalities. The efficiency and potential versatility of this approach was exemplified in the synthesis of C-methyl derivative 1 as target molecule.
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Affiliation(s)
- Ahmed I Khodair
- Fachbereich Chemie, Universität Konstanz, Fach M 725, D-78457 Konstanz, Germany
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35
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Kelm S, Gerlach J, Brossmer R, Danzer CP, Nitschke L. The ligand-binding domain of CD22 is needed for inhibition of the B cell receptor signal, as demonstrated by a novel human CD22-specific inhibitor compound. J Exp Med 2002; 195:1207-13. [PMID: 11994426 PMCID: PMC2193707 DOI: 10.1084/jem.20011783] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
CD22 is a B cell-specific transmembrane protein of the Siglec family. It binds specifically to alpha2,6-linked sialic acid (Sia) residues, which are also present on glycoproteins on the B cell surface. CD22 acts as a negative regulator in B cell receptor-mediated signaling by recruitment of Src homology 2 domain-containing tyrosine phosphatase (SHP)-1 to its intracellular tail. To analyze how ligand-binding of CD22 influences its intracellular signaling domain, we designed synthetic sialosides as inhibitors for the lectin domain of CD22. One of these compounds inhibited binding of human CD22-Fc to target cells over 200-fold better than Sia and was highly selective for human CD22. When Daudi cells or primary B cells were stimulated with anti-immunoglobulin (Ig)M in presence of this sialoside inhibitor, a higher Ca(2+) response was observed, similar to CD22-deficient B cells. Accordingly, a lower tyrosine-phosphorylation of CD22 and SHP-1 recruitment was demonstrated in presence of the sialoside. Thus, by interfering with ligand binding of CD22 on the B cell surface, we have shown for the first time that the lectin domain of CD22 has a direct, positive influence on its intracellular inhibitory domain. Also, we have developed a novel low molecular weight compound which can enhance the response of human B cells.
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Affiliation(s)
- Soerge Kelm
- Centre for Biomolecular Interactions Bremen, University Bremen, Department for Biology and Chemistry, 28334 Bremen, Germany
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36
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Affiliation(s)
- P R Crocker
- The Wellcome Trust Biocentre at Dundee, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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37
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Azuma Y, Sakanashi M, Matsumoto K. The effect of alpha2,6-linked sialic acid on anti-IgM antibody-induced apoptosis in Ramos cells. Glycoconj J 2001; 18:419-24. [PMID: 11925509 DOI: 10.1023/a:1014820316267] [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
Apoptosis in B cells is induced through the B cell antigen receptor (BCR) and affects the sialic acid recognition molecules on B cells. We investigated the effects of alpha(1)-acid glycoprotein (AGP), which mainly contains alpha2,6-linked sialic acid, on anti-IgM antibody (Ab)-induced apoptosis in Ramos cells, which are derived from Burkitt's lymphoma. When Ramos cells were incubated with anti-IgM-Ab in plates coated with AGP, neuraminidase-digested AGP (asAGP) or alpha2,3-sialylated AGP (2,3AGP), apoptosis was suppressed only in those coated with AGP. We also studied the effects of CD22, which is expressed on the surface of mature B cells and binds to sugar chains containing alpha2,6-linked sialic acid, with anti-CD22 monoclonal antibody (mAb). Anti-CD22mAb enhanced anti-IgM Ab-induced apoptosis in Ramos cells. These contradictory results suggested that the recognition molecules for alpha2,6-linked sialic acid on AGP, which inhibits B-cell apoptosis, is distinct from CD22, or that different binding domains of CD22 between alpha2,6-linked sialic acid and anti-CD22 mAb exert opposite functions of suppression or enhancement to anti-IgM Ab-induced B cells.
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MESH Headings
- Antibodies, Anti-Idiotypic/pharmacology
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacology
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Antigens, Differentiation, B-Lymphocyte/immunology
- Antigens, Differentiation, B-Lymphocyte/metabolism
- Apoptosis/drug effects
- B-Lymphocytes/cytology
- B-Lymphocytes/drug effects
- B-Lymphocytes/immunology
- Carbohydrate Conformation
- Cell Adhesion Molecules
- Cell Survival/drug effects
- DNA Fragmentation/drug effects
- Flow Cytometry
- Humans
- Lectins
- N-Acetylneuraminic Acid/chemistry
- N-Acetylneuraminic Acid/pharmacology
- Orosomucoid/chemistry
- Orosomucoid/pharmacology
- Sialic Acid Binding Ig-like Lectin 2
- Tumor Cells, Cultured
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Affiliation(s)
- Y Azuma
- Department of Clinical Chemistry, School of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan.
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38
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Affiliation(s)
- S Kelm
- Institute of Biochemistry, University of Kiel, Olshausenstrasse 40, 24098 Kiel, Germany
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39
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Nitschke L, Floyd H, Crocker PR. New functions for the sialic acid-binding adhesion molecule CD22, a member of the growing family of Siglecs. Scand J Immunol 2001; 53:227-34. [PMID: 11251878 DOI: 10.1046/j.1365-3083.2001.00868.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- L Nitschke
- Institute of Virology and Immunobiology, University of Würzburg, Versbacherstr. 7, 97078 Würzburg, Germany.
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40
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Floyd H, Nitschke L, Crocker PR. A novel subset of murine B cells that expresses unmasked forms of CD22 is enriched in the bone marrow: implications for B-cell homing to the bone marrow. Immunology 2000; 101:342-7. [PMID: 11106937 PMCID: PMC2327092 DOI: 10.1046/j.1365-2567.2000.00103.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD22 is a B-cell-restricted transmembrane protein, which acts as a negative regulator of B-cell signalling. CD22 also has lectin-like adhesive properties. When expressed on transfected fibroblasts, it is capable of mediating adhesion to other cells via recognition of cell-surface glycoconjugates terminating in alpha2,6-linked sialic acids. In previous studies in the mouse, CD22 was implicated as a bone marrow homing receptor for recirculating immunoglobulin D+ (IgD+) B cells through recognition of sialylated ligands on marrow sinusoidal endothelium. As the adhesive function of CD22 can be masked when alpha2,6-linked sialic acids are co-expressed at the cell surface, the aim of the present study was to investigate whether recirculating B cells have unmasked forms of CD22 that could be involved in bone marrow homing. Using alpha2,6-sialyllactose coupled to biotinylated polyacrylamide as a probe for detection of unmasked CD22, we showed that approximately 2-5% of IgD+ murine B cells in the spleen and mesenteric lymph nodes were able to bind this synthetic ligand. In the bone marrow, however, the fraction of IgD+ B cells with unmasked CD22 was increased by two- to fivefold. B cells from CD22-deficient mice were not stained with the polyacrylamide probe, confirming that staining of B cells in wild-type mice was caused by CD22 and not by other potential sialic acid-binding lectins. In conclusion, we have identified a new subset of mature B cells in the mouse with unmasked CD22. This subset of recirculating B cells may bind to CD22 ligands on bone marrow sinusoidal endothelium, leading to their selective homing and subsequent enrichment in this tissue.
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Affiliation(s)
- H Floyd
- The Wellcome Trust Biocentre at Dundee, Department of Biochemistry, University of Dundee, Dundee, UK
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41
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Abstract
Sialylation represents one of the most frequently occurring terminations of the oligosaccharide chains of glycoproteins and glycolipids. Sialic acid is commonly found alpha2,3- or alpha2,6-linked to galactose (Gal), alpha2,6-linked to N-acetylgalactosamine (GalNAc) or alpha2,8-linked to another sialic acid. The biosynthesis of the various linkages is mediated by the different members of the sialyltransferase family. The addition of sialic acid in alpha2,6-linkage to the galactose residue of lactosamine (type 2 chains) is catalyzed by beta-galactoside alpha2,6-sialyltransferase (ST6Gal.I). Although expressed by a single gene, this enzyme shows a complex pattern of regulation which allows its tissue- and stage-specific modulation. The cognate oligosaccharide structure, NeuAcalpha2,6Galbeta1,4GlcNAc, is widely distributed among tissues and is involved in biological processes such as the regulation of the immune response and the progression of colon cancer. This review summarizes the current knowledge on the biochemistry of ST6Gal.I and on the functional role of the sialyl-alpha2,6-lactosaminyl structure.
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Affiliation(s)
- F Dall'Olio
- Dipartimento di Patologia Sperimentale, Università di Bologna, Italy
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42
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Abstract
The Siglecs are a recently discovered family of sialic acid-binding lectins of the immunoglobulin (Ig) superfamily. We report a molecule showing homology to the six first reported Siglecs, with the closest relationship to Siglec-3(CD33), Siglec-5, and Siglec-6(OBBP-1). The extracellular portion has two Ig-like domains, with the amino-terminal V-set Ig domain including amino acid residues known to be involved in sialic acid recognition by other Siglecs. The cytoplasmic domain has putative sites of tyrosine phosphorylation shared with some Siglecs, including an Immuno-receptor Tyrosine-based Inhibitory Motif (ITIM). Expression of the full-length cDNA induces sialic acid-dependent binding to human erythrocytes. A recombinant chimeric form containing the extracellular Ig domains selectively recognizes the sequence Neu5Acalpha2-6Galbeta1-4Glc, and binding requires the side chain of sialic acid. Mutation of an arginine residue predicted to be critical for sialic acid binding abolishes both interactions. Taken together, our findings justify designation of the molecule as Siglec-7. Analysis of bacterial artificial chromosome (BAC) clones spanning the known human genomic location of Siglec-3 indicates that the Siglec-7 gene is also located on chromosome 19q13.3-13.4. Human tissues show strong expression of Siglec-7 mRNA in spleen, peripheral blood leukocytes, and liver. The combination of an extracellular sialic acid binding site and an intracellular ITIM motif suggests that this molecule is involved in trans-membrane regulatory signaling reactions.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/genetics
- Base Sequence
- COS Cells
- Chromosomes, Human, Pair 19
- DNA, Complementary/chemistry
- Erythrocytes/metabolism
- Gene Expression
- Humans
- Lectins
- Leukocytes/chemistry
- Liver/chemistry
- Molecular Sequence Data
- N-Acetylneuraminic Acid/metabolism
- N-Acetylneuraminic Acid/pharmacology
- RNA, Messenger/analysis
- Sequence Homology
- Spleen/chemistry
- Transfection
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Affiliation(s)
- T Angata
- Glycobiology Research and Training Center, Department of Medicine and Cancer Center, University of California San Diego, La Jolla, CA 92093, USA
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43
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Brinkman-Van der Linden EC, Varki A. New aspects of siglec binding specificities, including the significance of fucosylation and of the sialyl-Tn epitope. Sialic acid-binding immunoglobulin superfamily lectins. J Biol Chem 2000; 275:8625-32. [PMID: 10722702 DOI: 10.1074/jbc.275.12.8625] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The siglecs (sialic acid-binding immunoglobulin superfamily lectins) are immunoglobulin superfamily members recognizing sialylated ligands. Most prior studies of siglec specificities focused on alpha2-3- and alpha2-6-sialyllactos(amin)es and on one or two of the siglecs at a time. Here, we explore several new aspects of specificities of the first six reported siglecs, using sialylated glycans presented in multivalent form, on synthetic polyacrylamide backbones, or on mucin polypeptides. First, we report that binding of siglec-1 (sialoadhesin), siglec-3 (CD33), siglec-4a (myelin-associated glycoprotein), and siglec-5 to alpha2-3 sialyllactosamine is affected markedly by the presence of an alpha1-3-linked fucose. Thus, while siglecs may not interfere with selectin-mediated recognition, fucosylation could negatively regulate siglec binding. Second, in contrast to earlier studies, we find that siglec-3 prefers alpha2-6-sialyllactose. Third, siglec-5 binds alpha2-8-linked sialic acid, making it the siglec least specific for linkage recognition. Fourth, siglecs-2 (CD22), -3, -5, and -6 (obesity-binding protein 1) showed significant binding to sialyl-Tn (Neu5Acalpha2-6-GalNAc), a tumor marker associated with poor prognosis. Fifth, siglec-6 is an exception among siglecs in not requiring the glycerol side chain of sialic acid for recognition. Sixth, all siglecs require the carboxyl group of sialic acid for binding. Finally, the presentation of the sialyl-Tn epitope and/or more extended structures that include this motif may be important for optimal recognition by the siglecs. This was concluded from studies using ovine, bovine, and porcine submaxillary mucins and Chinese hamster ovary cells transfected with ST6GalNAc-I and/or the mucin polypeptide MUC1.
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Affiliation(s)
- E C Brinkman-Van der Linden
- Glycobiology Research and Training Center and Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
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44
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Brinkman-Van der Linden EC, Sjoberg ER, Juneja LR, Crocker PR, Varki N, Varki A. Loss of N-glycolylneuraminic acid in human evolution. Implications for sialic acid recognition by siglecs. J Biol Chem 2000; 275:8633-40. [PMID: 10722703 DOI: 10.1074/jbc.275.12.8633] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The common sialic acids of mammalian cells are N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc). Humans are an exception, because of a mutation in CMP-sialic acid hydroxylase, which occurred after our common ancestor with great apes. We asked if the resulting loss of Neu5Gc and increase in Neu5Ac in humans alters the biology of the siglecs, which are Ig superfamily members that recognize sialic acids. Human siglec-1 (sialoadhesin) strongly prefers Neu5Ac over Neu5Gc. Thus, humans have a higher density of siglec-1 ligands than great apes. Siglec-1-positive macrophages in humans are found primarily in the perifollicular zone, whereas in chimpanzees they also occur in the marginal zone and surrounding the periarteriolar lymphocyte sheaths. Although only a subset of chimpanzee macrophages express siglec-1, most human macrophages are positive. A known evolutionary difference is the strong preference of mouse siglec-2 (CD22) for Neu5Gc, contrasting with human siglec-2, which binds Neu5Ac equally well. To ask when the preference for Neu5Gc was adjusted in the human lineage, we cloned the first three extracellular domains of siglec-2 from all of the great apes and examined their preference. In fact, siglec-2 had evolved a higher degree of recognition flexibility before Neu5Gc was lost in humans. Human siglec-3 (CD33) and siglec-6 (obesity-binding protein 1) also recognize both Neu5Ac and Neu5Gc, and siglec-5 may have some preference for Neu5Gc. Others showed that siglec-4a (myelin-associated glycoprotein) prefers Neu5Ac over Neu5Gc. Thus, the human loss of Neu5Gc may alter biological processes involving siglec-1, and possibly, siglec-4a or -5.
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Affiliation(s)
- E C Brinkman-Van der Linden
- Glycobiology Research and Training Center and Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
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45
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Basset C, Durand V, Mimassi N, Pennec YL, Youinou P, Dueymes M. Enhanced sialyltransferase activity in B lymphocytes from patients with primary Sjögren's syndrome. Scand J Immunol 2000; 51:307-11. [PMID: 10736101 DOI: 10.1046/j.1365-3083.2000.00692.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Despite the indisputable role of immunoglobulin (Ig)A in the pathogenesis of primary Sjögren syndrome (pSS), the causative abnormality remains largely unknown. As an extension of our report that IgA is oversialylated in this disease, the thrust of the present study was to measure the sialyltransferase (ST) activity in B lymphocytes. ST containing lysates of B cells from 17 pSS patients and 10 controls, were obtained using a combination of detergents, and incubated with affinity purified IgA that had been previously desialylated. The deposition of cytidine 5' monophosphate sialic acid (SA) by ST from B cells onto IgA was detected by two ELISA based upon the use of biotinylated lectins (Sambucus nigra agglutinin which is specific for alpha2-6 SA and Maackia amurensis which is specific for alpha2-3 SA). In parallel, the amount of SA on IgA from ten of the 17 patients and eight of the 10 controls was assayed using the same method. An excess of alpha2-3 and alpha2-6 SA on IgA was found in those patients with excessive activity of alpha2-3 and alpha2-6 ST. Thus, IgA hypersialylation in pSS patients may result from undue activity of ST.
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Affiliation(s)
- C Basset
- Laboratory of Immunology; Department of Internal Medicine, Institut de Synergie des Sciences et de la Santé (I3S), Brest University Medical School, Brest, France
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46
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Nicoll G, Ni J, Liu D, Klenerman P, Munday J, Dubock S, Mattei MG, Crocker PR. Identification and characterization of a novel siglec, siglec-7, expressed by human natural killer cells and monocytes. J Biol Chem 1999; 274:34089-95. [PMID: 10567377 DOI: 10.1074/jbc.274.48.34089] [Citation(s) in RCA: 196] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We describe the characterization of sialic acid-binding Ig-like lectin-7 (siglec-7), a novel member of the siglec subgroup of the immunoglobulin superfamily. A full-length cDNA encoding siglec-7 was isolated from a human primary dendritic cell cDNA library. Siglec-7 is predicted to contain three extracellular immunoglobulin-like domains that comprise an N-terminal V-set domain and two C2-set domains, a transmembrane region and a cytoplasmic tail containing two tyrosine residues embodied in immunoreceptor tyrosine-based inhibition motif-like motifs. Overall, siglec-7 exhibited a high degree of sequence similarity to genes encoding CD33 (siglec-3), siglec-5, OBBP1/siglec-6, and OBBP-like protein and mapped to the same region on chromosome 19q13.3. When siglec-7 was expressed on COS or Chinese hamster ovary cells, it was able to mediate high levels of sialic acid-dependent binding to human erythrocytes and soluble sialoglycoconjugates, suggesting that it may be involved in cell-cell interactions. Among human peripheral blood leukocytes, siglec-7 was found to be present at low levels on granulocytes, intermediate levels on monocytes, and relatively high levels on a major subset of natural killer cells and a minor subset of CD8(+) T cells. Immunoprecipitation experiments indicated that siglec-7 is expressed as a monomer of approximately 65 kDa.
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MESH Headings
- 3T3 Cells
- Amino Acid Sequence
- Animals
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/immunology
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/immunology
- Blotting, Northern
- CHO Cells
- COS Cells
- Cell Line
- Chromosome Banding
- Chromosome Mapping
- Chromosomes, Human, Pair 9/genetics
- Cricetinae
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Female
- Gene Expression
- HL-60 Cells
- Humans
- Immunophenotyping
- In Situ Hybridization, Fluorescence
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Lectins
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/metabolism
- Male
- Mice
- Molecular Sequence Data
- Molecular Weight
- Monocytes/immunology
- Monocytes/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Tissue Distribution
- Tumor Cells, Cultured
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Affiliation(s)
- G Nicoll
- Medical Sciences Institute/Wellcome Trust Biocentre at Dundee Complex, Department of Biochemistry, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
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47
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Razi N, Varki A. Cryptic sialic acid binding lectins on human blood leukocytes can be unmasked by sialidase treatment or cellular activation. Glycobiology 1999; 9:1225-34. [PMID: 10536038 DOI: 10.1093/glycob/9.11.1225] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
We recently reported that the sialic acid-specific binding sites of CD22 molecules on B cells are masked by endogenous ligands, and can be unmasked by sialidase treatment or cellular activation. Here, we show that many other human blood leukocyte types have endogenous sialic acid binding sites that can be unmasked by sialidase treatment. Truncation of sialic acid side chains on the soluble probes used for detection abolishes all binding, indicating the specificity of the interaction for the details of sialic acid structure. There is limited overlap between alpha2-6- and alpha2-3-sialic acid-specific binding sites, which are unmasked on monocytes, natural killer cells, a minority of mature T cells, neutrophils, and some cultured human leukemic cell lines. Activation with phorbol ester and calcium ionophore causes spontaneous exposure of some of the binding sites, occurring over a period of minutes on neutrophils and several hours on monocytes and U937 leukemia cells. Activation is accompanied by some evidence for desialylation of cell surface molecules. Thus, many human blood cells have specific binding sites for sialic acids, masked by endogenous sialylated ligands. Cellular activation can unmask these sites, possibly by the action of an endogenous sialidase. The nearly universal masking of such sites in unactivated blood cells could explain why many of these sialic acid-binding lectins have not been previously discovered. Similar considerations may apply to sialic acid binding lectins of other cell types and tissues.
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Affiliation(s)
- N Razi
- Glycobiology Program and Cancer Center, Divisions of Hematology-Oncology, and Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
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48
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Lo NW, Lau JT. Transcription of the beta-galactoside alpha2,6-sialyltransferase gene (SIAT1) in B-lymphocytes: cell type-specific expression correlates with presence of the divergent 5'-untranslated sequence. Glycobiology 1999; 9:907-14. [PMID: 10460832 DOI: 10.1093/glycob/9.9.907] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A single gene, SIAT1, encodes ST6Gal I, the sialyltransferase that mediates transfer of alpha2,6-linked sialic acids to Galbeta1, 4GlcNAc termini of N-linked glycoproteins. In vivo, multiple SIAT1 mRNA forms, differing only in the 5'-untranslated region, are expressed in a tissue-specific manner. This mRNA heterogeneity has been attributed, at least in part, to transcription from a number of physically distinct promoter regions. In mature B-lymphocytes, SIAT1 transcription initiates at P2, a regulatory region known to function only in B-lineage cells. Bacterial chloramphenicol acetyltransferase (CAT) under the control of the P2 region encompassing 415 bp 5'- and 125 bp 3' of the transcriptional initiation site is efficiently expressed in Louckes, a mature B-lymphoblastoid cell line. In contrast, CAT expression in Reh, a T-null/B-null precursor line, and in HepG2, a hepatoma line, are 14-fold and >25-fold less than in Louckes, respectively. The data is consistent with the presence of cis -acting regulatory elements residing both 5' and 3' of the P2 transcriptional initiation site. At least 370 bp of 5'-flanking sequence, coinciding with the inclusion of AP2 and NF-kappaB sites, is necessary for high level expression in Louckes. Exon sequences 3' of the transcription start site are also important for expression. A segment from(+)32 to(+)125 (position(+)1 is transcription start site) is capable of exerting promoter-like activity in Louckes, but not in Reh or HepG2. CAT expression by P2 is negligible in Reh cells. However, enhanced CAT activity is not accompanied by elevated mRNA levels. This observation is consistent with the relief of translational restraints imposed by the(+)32 to(+)125 region. Together, the data demonstrate that efficient and cell-specific transcription regulation in mature B lymphocytes is contained in a 495 bp P2 segment that is comprised of 370 bp of 5'-flanking region and 125 bp of transcribed region of Exon X.
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Affiliation(s)
- N W Lo
- Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA
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49
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Abe Y, Smith CW, Katkin JP, Thurmon LM, Xu X, Mendoza LH, Ballantyne CM. Endothelial α2,6-Linked Sialic Acid Inhibits VCAM-1- Dependent Adhesion Under Flow Conditions. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.5.2867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
We have previously shown that costimulation of endothelial cells with IL-1 + IL-4 markedly inhibits VCAM-1-dependent adhesion under flow conditions. We hypothesized that sialic acids on the costimulated cell surfaces may contribute to the inhibition. Northern blot analyses showed that Galβ1-4GlcNAc α2,6-sialyltransferase (ST6N) mRNA was up-regulated in cultured HUVEC by IL-1 or IL-4 alone, but that the expression was enhanced by costimulation, whereas the level of Galβ1-4GlcNAc/Galβ1-3GalNAc α2,3-sialyltransferase (ST3ON) mRNA was unchanged. Removing both α2,6- and α2,3-linked sialic acids from IL-1 + IL-4-costimulated HUVEC by sialidase significantly increased VCAM-1-dependent adhesion, whereas removing α2,3-linked sialic acid alone had no effect; adenovirus-mediated overexpression of ST6N with costimulation almost abolished the adhesion, which was reversible by sialidase. The same treatments of IL-1-stimulated HUVEC had no effect. Lectin blotting showed that VCAM-1 is decorated with α2,6- but not α2,3-linked sialic acids. However, overexpression of α2,6-sialyltransferase did not increase α2,6-linked sialic acid on VCAM-1 but did increase α2,6-linked sialic acids on other proteins that remain to be identified. These results suggest that α2,6-linked sialic acids on a molecule(s) inducible by costimulation with IL-1 + IL-4 but not IL-1 alone down-regulates VCAM-1-dependent adhesion under flow conditions.
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Affiliation(s)
- Yasunori Abe
- *Speros Martel Section of Leukocyte Biology, Department of Pediatrics,
| | - C. Wayne Smith
- *Speros Martel Section of Leukocyte Biology, Department of Pediatrics,
- †Department of Microbiology and Immunology,
| | | | - Lisa M. Thurmon
- *Speros Martel Section of Leukocyte Biology, Department of Pediatrics,
| | - Xudong Xu
- ‡Pulmonary Medicine, Department of Pediatrics, and
| | | | - Christie M. Ballantyne
- *Speros Martel Section of Leukocyte Biology, Department of Pediatrics,
- §Section of Atherosclerosis, Department of Medicine, Baylor College of Medicine, Houston, TX 77030
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50
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Nitschke L, Floyd H, Ferguson DJ, Crocker PR. Identification of CD22 ligands on bone marrow sinusoidal endothelium implicated in CD22-dependent homing of recirculating B cells. J Exp Med 1999; 189:1513-8. [PMID: 10224292 PMCID: PMC2193059 DOI: 10.1084/jem.189.9.1513] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
CD22 is a B cell-specific transmembrane protein known to function as a negative regulator of B cell signaling. It has also been implicated in cell adhesion through recognition of alpha2,6-linked sialic acids on glycans of target cells. Previous studies showed that CD22-deficient mice had a strongly reduced population of mature recirculating B cells in the bone marrow despite normal B cell development. Using a soluble recombinant form of the receptor (CD22-Fc), we demonstrate here that sialylated ligands for CD22 are expressed on sinusoidal endothelial cells of murine bone marrow but not on endothelial cells in other tissues examined. Injection of CD22-Fc revealed that the CD22 ligands in the bone marrow were accessible to the circulation. Treatment of mice with either CD22-Fc or affinity-purified anti-CD22 antibody led to an approximately 50% reduction in mature recirculating B cells in the bone marrow without affecting numbers in the spleen. Finally, consistent with the notion that CD22 is a homing receptor, we show that compared with wild-type mice, CD22-deficient animals have a lower number of immunoglobulin M-secreting plasma cells in the bone marrow.
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Affiliation(s)
- L Nitschke
- Institute for Virology and Immunobiology, University of Würzburg, 97078 Würzburg, Germany
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