1
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Radovani B, Gudelj I. N-Glycosylation and Inflammation; the Not-So-Sweet Relation. Front Immunol 2022; 13:893365. [PMID: 35833138 PMCID: PMC9272703 DOI: 10.3389/fimmu.2022.893365] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/30/2022] [Indexed: 12/28/2022] Open
Abstract
Chronic inflammation is the main feature of many long-term inflammatory diseases such as autoimmune diseases, metabolic disorders, and cancer. There is a growing number of studies in which alterations of N-glycosylation have been observed in many pathophysiological conditions, yet studies of the underlying mechanisms that precede N-glycome changes are still sparse. Proinflammatory cytokines have been shown to alter the substrate synthesis pathways as well as the expression of glycosyltransferases required for the biosynthesis of N-glycans. The resulting N-glycosylation changes can further contribute to disease pathogenesis through modulation of various aspects of immune cell processes, including those relevant to pathogen recognition and fine-tuning the inflammatory response. This review summarizes our current knowledge of inflammation-induced N-glycosylation changes, with a particular focus on specific subsets of immune cells of innate and adaptive immunity and how these changes affect their effector functions, cell interactions, and signal transduction.
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Affiliation(s)
- Barbara Radovani
- Department of Biotechnology, University of Rijeka, Rijeka, Croatia
| | - Ivan Gudelj
- Department of Biotechnology, University of Rijeka, Rijeka, Croatia
- Genos Glycoscience Research Laboratory, Zagreb, Croatia
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2
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Matsuda Y, Watanabe T, Li XK. Approaches for Controlling Antibody-Mediated Allograft Rejection Through Targeting B Cells. Front Immunol 2021; 12:682334. [PMID: 34276669 PMCID: PMC8282180 DOI: 10.3389/fimmu.2021.682334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/17/2021] [Indexed: 01/14/2023] Open
Abstract
Both acute and chronic antibody-mediated allograft rejection (AMR), which are directly mediated by B cells, remain difficult to treat. Long-lived plasma cells (LLPCs) in bone marrow (BM) play a crucial role in the production of the antibodies that induce AMR. However, LLPCs survive through a T cell-independent mechanism and resist conventional immunosuppressive therapy. Desensitization therapy is therefore performed, although it is accompanied by severe side effects and the pathological condition may be at an irreversible stage when these antibodies, which induce AMR development, are detected in the serum. In other words, AMR control requires the development of a diagnostic method that predicts its onset before LLPC differentiation and enables therapeutic intervention and the establishment of humoral immune monitoring methods providing more detailed information, including individual differences in the susceptibility to immunosuppressive agents and the pathological conditions. In this study, we reviewed recent studies related to the direct or indirect involvement of immunocompetent cells in the differentiation of naïve-B cells into LLPCs, the limitations of conventional methods, and the possible development of novel control methods in the context of AMR. This information will significantly contribute to the development of clinical applications for AMR and improve the prognosis of patients who undergo organ transplantation.
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Affiliation(s)
- Yoshiko Matsuda
- Division of Transplantation Immunology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Takeshi Watanabe
- Laboratory of Immunology, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Xiao-Kang Li
- Division of Transplantation Immunology, National Research Institute for Child Health and Development, Tokyo, Japan
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3
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Barnard KN, Wasik BR, LaClair JR, Buchholz DW, Weichert WS, Alford-Lawrence BK, Aguilar HC, Parrish CR. Expression of 9- O- and 7,9- O-Acetyl Modified Sialic Acid in Cells and Their Effects on Influenza Viruses. mBio 2019; 10:e02490-19. [PMID: 31796537 PMCID: PMC6890989 DOI: 10.1128/mbio.02490-19] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 10/23/2019] [Indexed: 12/13/2022] Open
Abstract
Sialic acids (Sia) are widely displayed on the surfaces of cells and tissues. Sia come in a variety of chemically modified forms, including those with acetyl modifications at the C-7, C-8, and C-9 positions. Here, we analyzed the distribution and amounts of these acetyl modifications in different human and canine cells. Since Sia or their variant forms are receptors for influenza A, B, C, and D viruses, we examined the effects of these modifications on virus infections. We confirmed that 9-O-acetyl and 7,9-O-acetyl modified Sia are widely but variably expressed across cell lines from both humans and canines. Although they were expressed on the cell surfaces of canine MDCK cell lines, they were located primarily within the Golgi compartment of human HEK-293 and A549 cells. The O-acetyl modified Sia were expressed at low levels of 1 to 2% of total Sia in these cell lines. We knocked out and overexpressed the sialate O-acetyltransferase gene (CasD1) and knocked out the sialate O-acetylesterase gene (SIAE) using CRISPR/Cas9 editing. Knocking out CasD1 removed 7,9-O- and 9-O-acetyl Sia expression, confirming previous reports. However, overexpression of CasD1 and knockout of SIAE gave only modest increases in 9-O-acetyl levels in cells and no change in 7,9-O-acetyl levels, indicating that there are complex regulations of these modifications. These modifications were essential for influenza C and D infection but had no obvious effect on influenza A and B infection.IMPORTANCE Sialic acids are key glycans that are involved in many different normal cellular functions, as well as being receptors for many pathogens. However, Sia come in diverse chemically modified forms. Here, we examined and manipulated the expression of 7,9-O- and 9-O-acetyl modified Sia on cells commonly used in influenza virus and other research by engineering the enzymes that produce or remove the acetyl groups.
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Affiliation(s)
- Karen N Barnard
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Brian R Wasik
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Justin R LaClair
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - David W Buchholz
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Wendy S Weichert
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Brynn K Alford-Lawrence
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Hector C Aguilar
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Colin R Parrish
- Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
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4
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Shi Y, Zhu R, Xue Z, Han J, Han S. An in cellulo-activated multicolor cell labeling approach used to image dying cell clearance. Analyst 2019; 144:4687-4693. [DOI: 10.1039/c9an00904c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dying cell clearance is critical for myriad biological processes such as tissue homeostasis.
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Affiliation(s)
- Yilong Shi
- State key Laboratory of Cellular Stress Biology
- Innovation Center for Cell Signalling Network
- School of Life Sciences
- Xiamen University
- Xiamen, Fujian
| | - Rui Zhu
- State Key Laboratory for Physical Chemistry of Solid Surfaces
- Department of Chemical Biology
- College of Chemistry and Chemical Engineering
- the Key Laboratory for Chemical Biology of Fujian Province
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation
| | - Zhongwei Xue
- State Key Laboratory for Physical Chemistry of Solid Surfaces
- Department of Chemical Biology
- College of Chemistry and Chemical Engineering
- the Key Laboratory for Chemical Biology of Fujian Province
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation
| | - Jiahuai Han
- State key Laboratory of Cellular Stress Biology
- Innovation Center for Cell Signalling Network
- School of Life Sciences
- Xiamen University
- Xiamen, Fujian
| | - Shoufa Han
- State Key Laboratory for Physical Chemistry of Solid Surfaces
- Department of Chemical Biology
- College of Chemistry and Chemical Engineering
- the Key Laboratory for Chemical Biology of Fujian Province
- The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation
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5
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Clark EA, Giltiay NV. CD22: A Regulator of Innate and Adaptive B Cell Responses and Autoimmunity. Front Immunol 2018; 9:2235. [PMID: 30323814 PMCID: PMC6173129 DOI: 10.3389/fimmu.2018.02235] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 09/07/2018] [Indexed: 12/12/2022] Open
Abstract
CD22 (Siglec 2) is a receptor predominantly restricted to B cells. It was initially characterized over 30 years ago and named “CD22” in 1984 at the 2nd International workshop in Boston (1). Several excellent reviews have detailed CD22 functions, CD22-regulated signaling pathways and B cell subsets regulated by CD22 or Siglec G (2–4). This review is an attempt to highlight recent and possibly forgotten findings. We also describe the role of CD22 in autoimmunity and the great potential for CD22-based immunotherapeutics for the treatment of autoimmune diseases such as systemic lupus erythematosus (SLE).
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Affiliation(s)
- Edward A Clark
- Department of Immunology, University of Washington, Seattle, WA, United States.,Division of Rheumatology, Department of Medicine, University of Washington, Seattle, WA, United States
| | - Natalia V Giltiay
- Division of Rheumatology, Department of Medicine, University of Washington, Seattle, WA, United States
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6
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Pore D, Huang E, Dejanovic D, Parameswaran N, Cheung MB, Gupta N. Cutting Edge: Deletion of Ezrin in B Cells of Lyn-Deficient Mice Downregulates Lupus Pathology. THE JOURNAL OF IMMUNOLOGY 2018; 201:1353-1358. [PMID: 30021765 DOI: 10.4049/jimmunol.1800168] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 06/28/2018] [Indexed: 12/19/2022]
Abstract
Genetic deletion of the Src family tyrosine kinase Lyn in mice recapitulates human systemic lupus erythematosus, characterized by hyperactive BCR signaling, splenomegaly, autoantibody generation, and glomerulonephritis. However, the molecular regulators of autoimmunity in Lyn-deficient mice and in human lupus remain poorly characterized. In this study, we report that conditional deletion of the membrane-cytoskeleton linker protein ezrin in B cells of Lyn-deficient mice (double knockout [DKO] mice) ameliorates B cell activation and lupus pathogenesis. B cells from DKO mice respond poorly to BCR stimulation, with severe downregulation of major signaling pathways. DKO mice exhibit reduced splenomegaly as well as significantly lower levels of autoantibodies against a variety of autoantigens, including dsDNA, histone, and chromatin. Leukocyte infiltration and deposition of IgG and complement component C3 in the kidney glomeruli of DKO mice are markedly reduced. Our data demonstrate that ezrin is a novel molecular regulator of B cell-associated lupus pathology.
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Affiliation(s)
- Debasis Pore
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Emily Huang
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Dina Dejanovic
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Neetha Parameswaran
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Michael B Cheung
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Neetu Gupta
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
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7
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SIAE Rare Variants in Juvenile Idiopathic Arthritis and Primary Antibody Deficiencies. J Immunol Res 2017; 2017:1514294. [PMID: 28900629 PMCID: PMC5576406 DOI: 10.1155/2017/1514294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 07/18/2017] [Indexed: 01/23/2023] Open
Abstract
Sialic acid acetylesterase (SIAE) deficiency was suggested to lower the levels of ligands for sialic acid-binding immunoglobulin-like receptors, decreasing the threshold for B-cell activation. In humans, studies of rare heterozygous loss-of-function mutations in SIAE gene in common autoimmune diseases, including juvenile idiopathic arthritis (JIA), yielded inconsistent results. Considering the distinct pathogenesis of the two main subtypes of JIA, autoinflammatory systemic (sJIA) and autoimmune oligo/polyarticular (aJIA), and a predisposition to autoimmunity displayed by patients and families with primary antibody deficiencies (PADs), the aim of our study was to analyze whether SIAE rare variants are associated with both the phenotype of JIA and the autoimmunity risk in families with PADs. A cohort of 69 patients with JIA, 117 healthy children, 54 patients, and family members with PADs were enrolled in the study. Three novel SIAE variants (p.Q343P, p.Y495X, and c.1320+33T>C) were found only in patients with aJIA but interestingly also in their healthy relatives without autoimmunity, while none of PAD patients or their relatives carried SIAE defects. Our results show that SIAE rare variants are not causative of autoimmunity as single defects.
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8
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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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9
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Mechanisms of disease: The human N-glycome. Biochim Biophys Acta Gen Subj 2016; 1860:1574-82. [DOI: 10.1016/j.bbagen.2015.10.016] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/03/2015] [Accepted: 10/15/2015] [Indexed: 12/20/2022]
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10
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Mahajan VS, Demissie E, Mattoo H, Viswanadham V, Varki A, Morris R, Pillai S. Striking Immune Phenotypes in Gene-Targeted Mice Are Driven by a Copy-Number Variant Originating from a Commercially Available C57BL/6 Strain. Cell Rep 2016; 15:1901-9. [PMID: 27210752 DOI: 10.1016/j.celrep.2016.04.080] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 03/28/2016] [Accepted: 04/21/2016] [Indexed: 12/21/2022] Open
Abstract
We describe a homozygous copy-number variant that disrupts the function of Dock2 in a commercially available C57BL/6 mouse strain that is widely used for backcrossing. This Dock2 allele was presumed to have spontaneously arisen in a colony of Irf5 knockout mice. We discovered that this allele has actually been inadvertently backcrossed into multiple mutant mouse lines, including two engineered to be deficient in Siae and Cmah. This particular commercially obtained subline of C57BL/6 mice also exhibits several striking immune phenotypes that have been previously described in the context of Dock2 deficiency. Inadvertent backcrossing of a number of gene-targeted mice into this background has complicated the interpretation of several immunological studies. In light of these findings, published studies involving immune or hematopoietic phenotypes in which these C57BL/6 mice have been used as controls, as experimental animals, or for backcrossing will need to be reinterpreted.
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Affiliation(s)
- Vinay S Mahajan
- Ragon Institute of MGH, MIT and Harvard, 400 Technology Square, Cambridge, MA 02139, USA
| | - Ezana Demissie
- Ragon Institute of MGH, MIT and Harvard, 400 Technology Square, Cambridge, MA 02139, USA
| | - Hamid Mattoo
- Ragon Institute of MGH, MIT and Harvard, 400 Technology Square, Cambridge, MA 02139, USA
| | - Vinay Viswanadham
- Ragon Institute of MGH, MIT and Harvard, 400 Technology Square, Cambridge, MA 02139, USA
| | - Ajit Varki
- Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Robert Morris
- Ragon Institute of MGH, MIT and Harvard, 400 Technology Square, Cambridge, MA 02139, USA
| | - Shiv Pillai
- Ragon Institute of MGH, MIT and Harvard, 400 Technology Square, Cambridge, MA 02139, USA.
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11
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Characterization of a sialate-O-acetylesterase (NanS) from the oral pathogen Tannerella forsythia that enhances sialic acid release by NanH, its cognate sialidase. Biochem J 2015; 472:157-67. [DOI: 10.1042/bj20150388] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 09/16/2015] [Indexed: 12/11/2022]
Abstract
We characterize a novel bacterial sialate-O-acetylesterase potentially important for the nutrition of oral pathogens causing periodontal disease by enhancing their ability to harvest sialic acid sugar. Its high activity and stability indicate that it can also be used in glycan pharmacoanalytics.
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12
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Orizio F, Damiati E, Giacopuzzi E, Benaglia G, Pianta S, Schauer R, Schwartz-Albiez R, Borsani G, Bresciani R, Monti E. Human sialic acid acetyl esterase: Towards a better understanding of a puzzling enzyme. Glycobiology 2015; 25:992-1006. [DOI: 10.1093/glycob/cwv034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 05/17/2015] [Indexed: 01/09/2023] Open
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13
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Macauley MS, Crocker PR, Paulson JC. Siglec-mediated regulation of immune cell function in disease. Nat Rev Immunol 2014; 14:653-66. [PMID: 25234143 DOI: 10.1038/nri3737] [Citation(s) in RCA: 743] [Impact Index Per Article: 74.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
All mammalian cells display a diverse array of glycan structures that differ from those that are found on microbial pathogens. Siglecs are a family of sialic acid-binding immunoglobulin-like receptors that participate in the discrimination between self and non-self, and that regulate the function of cells in the innate and adaptive immune systems through the recognition of their glycan ligands. In this Review, we describe the recent advances in our understanding of the roles of Siglecs in the regulation of immune cell function in infectious diseases, inflammation, neurodegeneration, autoimmune diseases and cancer.
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Affiliation(s)
- Matthew S Macauley
- Departments of Cell and Molecular Biology, Immunology and Microbial Science, and Physiological Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Paul R Crocker
- Division of Cell Signalling and Immunology, Wellcome Trust Building, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - James C Paulson
- Departments of Cell and Molecular Biology, Immunology and Microbial Science, and Physiological Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA
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14
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Chen GY, Brown NK, Zheng P, Liu Y. Siglec-G/10 in self-nonself discrimination of innate and adaptive immunity. Glycobiology 2014; 24:800-6. [PMID: 24996822 DOI: 10.1093/glycob/cwu068] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Siglec-G/10 is broadly expressed on B cells, dendritic cells and macrophage subsets. It binds strongly to CD24, a small glycosyl-phosphatidylinositol-anchored sialoprotein, in a sialylation-dependent manner. Targeted mutation of Siglecg dramatically elevates the level of natural IgM antibodies and its producer, B1 B cells. Incorporation of Siglec-G ligands to both T-dependent and T-independent immunogens reduces antibody production and induces B-cell tolerance to subsequent antigen challenges. By interacting with CD24, Siglec-G suppresses inflammatory responses to danger (damage)-associated molecular patterns, such as heat-shock proteins and high mobility group protein 1, but not to Toll-like receptor ligands. By a CD24-independent mechanism, Siglec-G has been shown to associate with Cbl to cause degradation of retinoic acid-inducible gene 1 and reduce production of type I interferon in response to RNA virus infection. The negative regulation by Siglec-G/10 may provide a mechanism for the host to discriminate between infectious nonself and noninfectious self, as envisioned by the late Dr. Charles A. Janeway.
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Affiliation(s)
- Guo-Yun Chen
- Center for Cancer and Immunology Research, Children's National Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010, USA Department of Pediatrics, School of Medicine and Health Sciences, George Washington University
| | - Nicholas K Brown
- Center for Cancer and Immunology Research, Children's National Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010, USA
| | - Pan Zheng
- Center for Cancer and Immunology Research, Children's National Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010, USA Division of Pathology, Children's National Medical Center, Washington, DC 20010, USA
| | - Yang Liu
- Center for Cancer and Immunology Research, Children's National Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010, USA
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15
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Abstract
Why exactly some individuals develop autoimmune disorders remains unclear. The broadly accepted paradigm is that genetic susceptibility results in some break in immunological tolerance, may enhance the availability of autoantigens, and may enhance inflammatory responses. Some environmental insults that occur on this background of susceptibility may then contribute to autoimmunity. In this review we discuss some aspects related to inhibitory signaling and rare genetic variants, as well as additional factors that might contribute to autoimmunity including the possible role of clonal somatic mutations, the role of epigenetic events and the contribution of the intestinal microbiome. Genetic susceptibility alleles generally contribute to the loss of immunological tolerance, the increased availability of autoantigens, or an increase in inflammation. Apart from common genetic variants, rare loss-of-function genetic variants may also contribute to the pathogenesis of autoimmunity. Studies of an inhibitory signaling pathway in B cells helped identify a negative regulatory enzyme called sialic acid acetyl esterase. The study of rare genetic variants of this enzyme provides an illustrative example showing the importance of detailed functional analyses of variant alleles and the need to exclude functionally normal common or rare genetic variants from analysis. It has also become clear that pathways that are functionally impacted by either common or rare defective variants can also be more significantly compromised by gene expression changes that may result from epigenetic alterations. Another important and evolving area that has been discussed relates to the role of the intestinal microbiome in influencing helper T cell polarization and the development of autoimmunity.
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Affiliation(s)
- Shiv Pillai
- Massachusetts General Hospital, Center for Cancer Research, Harvard Medical School, Boston, MA 02129, USA.
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16
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Chellappa V, Taylor KN, Pedrick K, Donado C, Netravali IA, Haider K, Cariappa A, Dalomba NF, Pillai S. M89V Sialic acid Acetyl Esterase (SIAE) and all other non-synonymous common variants of this gene are catalytically normal. PLoS One 2013; 8:e53453. [PMID: 23308225 PMCID: PMC3538537 DOI: 10.1371/journal.pone.0053453] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 11/29/2012] [Indexed: 11/18/2022] Open
Abstract
Catalytically defective rare variants of Sialic acid Acetyl Esterase (SIAE) have previously been linked to autoimmunity. Studies presented here confirm that the M89V SIAE protein and all other products of common variant alleles of SIAE are catalytically normal. Although overexpressing transfected non-lymphoid cells secrete small amounts of SIAE that can associate with the cell surface, normal human lymphocytes do not exhibit cell surface SIAE, supporting genetic evidence in mice that indicates that this protein functions in a lymphocyte intrinsic manner. Analyses of the plasma proteome also indicate that SIAE is not secreted in vivo. A re-analysis exclusively of catalytically defective rare variant alleles of SIAE in subjects in which this gene was completely sequenced confirmed an association of SIAE with autoimmunity. A subset of catalytically defective rare variant SIAE alleles has previously been typed in a large genotyping study comparing a diverse group of disease subjects and controls; our re-analysis of this data shows that catalytically defective alleles are enriched in disease subjects. These data suggest that SIAE may be associated with autoimmunity and that further study of catalytically defective rare variant SIAE alleles in terms of autoimmune disease susceptibility is strongly warranted.
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Affiliation(s)
- Vasant Chellappa
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, Massachusetts, United States of America
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17
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Gan EH, MacArthur K, Mitchell AL, Pearce SHS. The role of functionally defective rare germline variants of sialic acid acetylesterase in autoimmune Addison's disease. Eur J Endocrinol 2012; 167:825-8. [PMID: 23011869 PMCID: PMC3494867 DOI: 10.1530/eje-12-0579] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Autoimmune Addison's disease (AAD) is a rare condition with a complex genetic basis. A panel of rare and functionally defective genetic variants in the sialic acid acetylesterase (SIAE) gene has recently been implicated in several common autoimmune conditions. We performed a case-control study to determine whether these rare variants are associated with a rarer condition, AAD. METHOD We analysed nine SIAE gene variants (W48X, M89V, C196F, C226G, R230W, T312M, Y349C, F404S and R479C) in a United Kingdom cohort of 378 AAD subjects and 387 healthy controls. All samples were genotyped using Sequenom iPlex chemistry to characterise primer extension products. RESULTS A heterozygous rare allele at codon 312 (312*M) was found in one AAD patient (0.13%) but was not detected in the healthy controls. The commoner, functionally recessive variant at codon 89 (89*V) was found to be homozygous in two AAD patients but was only found in the heterozygous state in controls. Taking into account all nine alleles examined, 4/378 (1.06%) AAD patients and 1/387 (0.25%) healthy controls carried the defective SIAE alleles, with a calculated odds ratio of 4.13 (95% CI 0.44-97.45, two-tailed P value 0.212, NS). CONCLUSION We demonstrated the presence of 89*V homozygotes and the 312*M rare allele in the AAD cohort, but overall, our analysis does not support a role for rare variants in SIAE in the pathogenesis of AAD. However, the relatively small collection of AAD patients limits the power to exclude a small effect.
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Affiliation(s)
- Earn H Gan
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
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18
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Abstract
Sialic acids are a diverse family of monosaccharides widely expressed on all cell surfaces of vertebrates and so-called "higher" invertebrates, and on certain bacteria that interact with vertebrates. This overview surveys examples of biological roles of sialic acids in immunity, with emphasis on an evolutionary perspective. Given the breadth of the subject, the treatment of individual topics is brief. Subjects discussed include biophysical effects regulation of factor H; modulation of leukocyte trafficking via selectins; Siglecs in immune cell activation; sialic acids as ligands for microbes; impact of microbial and endogenous sialidases on immune cell responses; pathogen molecular mimicry of host sialic acids; Siglec recognition of sialylated pathogens; bacteriophage recognition of microbial sialic acids; polysialic acid modulation of immune cells; sialic acids as pathogen decoys or biological masks; modulation of immunity by sialic acid O-acetylation; sialic acids as antigens and xeno-autoantigens; antisialoglycan antibodies in reproductive incompatibility; and sialic-acid-based blood groups.
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Affiliation(s)
- Ajit Varki
- Glycobiology Research and Training Center, Department of Medicine, University of California at San Diego, La Jolla, 92093-0687, USA.
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Deleury E, Dubreuil G, Elangovan N, Wajnberg E, Reichhart JM, Gourbal B, Duval D, Baron OL, Gouzy J, Coustau C. Specific versus non-specific immune responses in an invertebrate species evidenced by a comparative de novo sequencing study. PLoS One 2012; 7:e32512. [PMID: 22427848 PMCID: PMC3299671 DOI: 10.1371/journal.pone.0032512] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 01/27/2012] [Indexed: 12/27/2022] Open
Abstract
Our present understanding of the functioning and evolutionary history of invertebrate innate immunity derives mostly from studies on a few model species belonging to ecdysozoa. In particular, the characterization of signaling pathways dedicated to specific responses towards fungi and Gram-positive or Gram-negative bacteria in Drosophila melanogaster challenged our original view of a non-specific immunity in invertebrates. However, much remains to be elucidated from lophotrochozoan species. To investigate the global specificity of the immune response in the fresh-water snail Biomphalaria glabrata, we used massive Illumina sequencing of 5′-end cDNAs to compare expression profiles after challenge by Gram-positive or Gram-negative bacteria or after a yeast challenge. 5′-end cDNA sequencing of the libraries yielded over 12 millions high quality reads. To link these short reads to expressed genes, we prepared a reference transcriptomic database through automatic assembly and annotation of the 758,510 redundant sequences (ESTs, mRNAs) of B. glabrata available in public databases. Computational analysis of Illumina reads followed by multivariate analyses allowed identification of 1685 candidate transcripts differentially expressed after an immune challenge, with a two fold ratio between transcripts showing a challenge-specific expression versus a lower or non-specific differential expression. Differential expression has been validated using quantitative PCR for a subset of randomly selected candidates. Predicted functions of annotated candidates (approx. 700 unisequences) belonged to a large extend to similar functional categories or protein types. This work significantly expands upon previous gene discovery and expression studies on B. glabrata and suggests that responses to various pathogens may involve similar immune processes or signaling pathways but different genes belonging to multigenic families. These results raise the question of the importance of gene duplication and acquisition of paralog functional diversity in the evolution of specific invertebrate immune responses.
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Affiliation(s)
- Emeline Deleury
- INRA/CNRS/UNS, Institut Sophia Agrobiotech, Sophia Antipolis, France
| | | | | | - Eric Wajnberg
- INRA/CNRS/UNS, Institut Sophia Agrobiotech, Sophia Antipolis, France
| | | | - Benjamin Gourbal
- CNRS, UMR 5244, Ecologie et Evolution des Interactions (2EI), Université de Perpignan Via Domitia, Perpignan, France
| | - David Duval
- CNRS, UMR 5244, Ecologie et Evolution des Interactions (2EI), Université de Perpignan Via Domitia, Perpignan, France
| | - Olga Lucia Baron
- INRA/CNRS/UNS, Institut Sophia Agrobiotech, Sophia Antipolis, France
- UdS, UPR 9022 CNRS, IBMC, 15 rue Rene Descartes, Strasbourg, France
| | - Jérôme Gouzy
- INRA/CNRS, UMR441/2594, Laboratoire Interactions Plantes Micro-organismes, Chemin de Borde Rouge, Castanet Tolosan, France
| | - Christine Coustau
- INRA/CNRS/UNS, Institut Sophia Agrobiotech, Sophia Antipolis, France
- * E-mail:
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20
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Paulson JC, Macauley MS, Kawasaki N. Siglecs as sensors of self in innate and adaptive immune responses. Ann N Y Acad Sci 2012; 1253:37-48. [PMID: 22288608 DOI: 10.1111/j.1749-6632.2011.06362.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Siglecs are expressed on most white blood cells of the immune system and are known to modulate the activity of cell signaling receptors via regulatory motifs in their cytoplasmic domains. This immunoglobulin subfamily of coreceptors recognize sialic acid containing glycans as ligands, which are found on glycoproteins and glycolipids of all mammalian cells. By virtue of their ability to recognize this common structural element, siglecs are increasingly recognized for their ability to help immune cells distinguish between self and nonself, and dampen autoimmune responses.
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Affiliation(s)
- James C Paulson
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA.
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21
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Muthana SM, Campbell CT, Gildersleeve JC. Modifications of glycans: biological significance and therapeutic opportunities. ACS Chem Biol 2012; 7:31-43. [PMID: 22195988 DOI: 10.1021/cb2004466] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Carbohydrates play a central role in a wide range of biological processes. As with nucleic acids and proteins, modifications of specific sites within the glycan chain can modulate a carbohydrate's overall biological function. For example, acylation, methylation, sulfation, epimerization, and phosphorylation can occur at various positions within a carbohydrate to modulate bioactivity. Therefore, there is significant interest in identifying discrete carbohydrate modifications and understanding their biological effects. Additionally, enzymes that catalyze those modifications and proteins that bind modified glycans provide numerous targets for therapeutic intervention. This review will focus on modifications of glycans that occur after the oligomer/polymer has been assembled, generally referred to as post-glycosylational modifications.
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Affiliation(s)
- Saddam M. Muthana
- Chemical Biology Laboratory, National Cancer Institute, NCI-Frederick, Frederick, Maryland 21702, United States
| | - Christopher T. Campbell
- Chemical Biology Laboratory, National Cancer Institute, NCI-Frederick, Frederick, Maryland 21702, United States
| | - Jeffrey C. Gildersleeve
- Chemical Biology Laboratory, National Cancer Institute, NCI-Frederick, Frederick, Maryland 21702, United States
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22
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Abstract
Sialic acid-binding Ig-like lectins, or Siglecs, vary in their specificity for sialic acid-containing ligands and are mainly expressed by cells of the immune system. Many Siglecs are inhibitory receptors expressed in innate immune cells that regulate inflammation mediated by damage-associated and pathogen-associated molecular patterns (DAMPs and PAMPs). This family also includes molecules involved in adhesion and phagocytosis and receptors that can associate with the ITAM-containing DAP12 adaptor. Siglecs contribute to the inhibition of immune cells both by binding to cis ligands (expressed in the same cells) and by responding to pathogen-derived sialoglycoconjugates. They can help maintain tolerance in B lymphocytes, modulate the activation of conventional and plasmacytoid dendritic cells, and contribute to the regulation of T cell function both directly and indirectly. Siglecs modulate immune responses, influencing almost every cell in the immune system, and are of relevance both in health and disease.
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Affiliation(s)
- Shiv Pillai
- Center for Cancer Research, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, USA.
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23
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Sang A, Yin Y, Zheng YY, Morel L. Animal Models of Molecular Pathology. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 105:321-70. [DOI: 10.1016/b978-0-12-394596-9.00010-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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24
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Pillai S, Mattoo H, Cariappa A. B cells and autoimmunity. Curr Opin Immunol 2011; 23:721-31. [PMID: 22119110 DOI: 10.1016/j.coi.2011.10.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 10/17/2011] [Accepted: 10/27/2011] [Indexed: 12/21/2022]
Abstract
There is a growing appreciation for the role for B cells in autoimmune disorders in which inflammation is driven by T cells, in addition to the well-established role for B cells in autoimmune disorders characterized by pathogenic auto-antibodies. Current information on tolerance checkpoints in B cells, B cell depletion, BAFF blockade, regulatory B cells and clonal ignorance mediated by the SIAE/Siglec pathway will be reviewed.
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Affiliation(s)
- Shiv Pillai
- Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, United States.
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25
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Held W, Mariuzza RA. Cis-trans interactions of cell surface receptors: biological roles and structural basis. Cell Mol Life Sci 2011; 68:3469-78. [PMID: 21863376 PMCID: PMC11115084 DOI: 10.1007/s00018-011-0798-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 08/08/2011] [Accepted: 08/08/2011] [Indexed: 10/17/2022]
Abstract
Cell surface receptors bind ligands expressed on other cells (in trans) in order to communicate with neighboring cells. However, an increasing number of cell surface receptors are found to also interact with ligands expressed on the same cell (in cis). These observations raise questions regarding the biological role of such cis interactions. Specifically, it is important to know whether cis and trans binding have distinct functional effects and, if so, how a single cell discriminates between interactions in cis versus trans. Further, what are the structural features that allow certain cell surface receptors to engage ligand both on the same as well as on an apposed cell membrane? Here, we summarize known examples of receptors that display cis-trans binding and discuss the emerging diversity of biological roles played by these unconventional two-way interactions, along with their structural basis.
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Affiliation(s)
- Werner Held
- Ludwig Center for Cancer Research of the University of Lausanne, 1066 Epalinges, Switzerland.
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26
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Stanley M, Mayr J, Huber W, Vlasak R, Streicher H. Synthesis and inhibitory activity of sialic acid derivatives targeted at viral sialate-O-acetylesterases. Eur J Med Chem 2011; 46:2852-60. [PMID: 21524502 PMCID: PMC7111470 DOI: 10.1016/j.ejmech.2011.04.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 03/25/2011] [Accepted: 04/02/2011] [Indexed: 11/18/2022]
Abstract
A series of sialosides modified at the 4- and 9-hydroxy group were synthesised and tested for inhibition of the viral haemagglutinin-esterase activity from various Orthomyxoviruses and Coronaviruses. While no inhibition of the sialate-4-O-acetylesterases from mouse hepatitis virus strain S or sialodacryoadenitis virus was found, a 9-O-methyl derivative displayed inhibitory activity against recombinant sialate-9-O-acetylesterase from influenza C virus.
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Affiliation(s)
- Mathew Stanley
- Department of Chemistry and Biochemistry, University of Sussex, Brighton, BN1 9QG, UK
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27
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Long JZ, Cravatt BF. The metabolic serine hydrolases and their functions in mammalian physiology and disease. Chem Rev 2011; 111:6022-63. [PMID: 21696217 DOI: 10.1021/cr200075y] [Citation(s) in RCA: 299] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jonathan Z Long
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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Rangarajan ES, Ruane KM, Proteau A, Schrag JD, Valladares R, Gonzalez CF, Gilbert M, Yakunin AF, Cygler M. Structural and enzymatic characterization of NanS (YjhS), a 9-O-Acetyl N-acetylneuraminic acid esterase from Escherichia coli O157:H7. Protein Sci 2011; 20:1208-19. [PMID: 21557376 DOI: 10.1002/pro.649] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 04/15/2011] [Accepted: 04/18/2011] [Indexed: 11/08/2022]
Abstract
There is a high prevalence of sialic acid in a number of different organisms, resulting in there being a myriad of different enzymes that can exploit it as a fermentable carbon source. One such enzyme is NanS, a carbohydrate esterase that we show here deacetylates the 9 position of 9-O-sialic acid so that it can be readily transported into the cell for catabolism. Through structural studies, we show that NanS adopts a SGNH hydrolase fold. Although the backbone of the structure is similar to previously characterized family members, sequence comparisons indicate that this family can be further subdivided into two subfamilies with somewhat different fingerprints. NanS is the founding member of group II. Its catalytic center contains Ser19 and His301 but no Asp/Glu is present to form the classical catalytic triad. The contribution of Ser19 and His301 to catalysis was confirmed by mutagenesis. In addition to structural characterization, we have mapped the specificity of NanS using a battery of substrates.
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29
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Szymański K, Skórka A, Szypowska A, Bednarczuk T, Płoski R. Functionally defective germline variant of sialic acid acetylesterase (Met89Val) is not associated with type 1 diabetes mellitus and Graves' disease in a Polish population. ACTA ACUST UNITED AC 2011; 78:214-6. [PMID: 21615338 DOI: 10.1111/j.1399-0039.2011.01703.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Recently, rare genotypes encoding defective variants of sialic acid acetylesterase (SIAE), such as homozygous Met89Val substitution, were strongly associated [odds ratio (OR) = 8] with a panel of autoimmune diseases including type 1 diabetes mellitus (T1DM). Our purpose was to replicate this finding in T1DM and explore whether Met89Val predisposes to Graves' diseases (GD). We studied 561 GD patients, 379 T1DM patients and 1822 controls. The prevalence of Met89Val homozygosity was similar among patients (GD: 0.4%, n = 2; T1DM: 0.3%, n = 1) and controls (0.4%, n = 7) yielding OR of 0.93 [95% confidence interval (CI): 0.19-4.48, P = 0.9] and 0.69 (95% CI: 0.08-5.59, P = 0.71) for GD and T1DM, respectively. We conclude that further studies are needed before the proposed strong effect of defective SIAE variants on susceptibility to autoimmunity can be universally accepted.
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Affiliation(s)
- K Szymański
- Department of Medical Genetics, Centre for Biostructure, Medical University of Warsaw, Warsaw, Poland
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30
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Inhibitory receptors specific for MHC class I educate murine NK cells but not CD8αα intestinal intraepithelial T lymphocytes. Blood 2011; 118:339-47. [PMID: 21613250 DOI: 10.1182/blood-2011-01-331124] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The engagement of inhibitory receptors specific for major histocompatibility complex class I (MHC-I) molecules educates natural killer (NK) cells, meaning the improvement of the response of activation receptors to subsequent stimulation. It is not known whether inhibitory MHC-I receptors educate only NK cells or whether they improve the responsiveness of all cell types, which express them. To address this issue, we analyzed the expression of inhibitory MHC-I receptors on intestinal intraepithelial lymphocytes (iIELs) and show that T-cell receptor (TCR)-αβ CD8αα iIELs express multiple inhibitory receptors specific for MHC-I molecules, including CD94/NKG2A, Ly49A, and Ly49G2. However, the presence of MHC-I ligand for these receptors did not improve the response of iIELs to activation via the TCR. The absence of iIEL education by MHC-I receptors was not related to a lack of inhibitory function of these receptors in iIELs and a failure of these receptors to couple to the TCR. Thus, unlike NK cells, iIELs do not undergo an MHC-I-guided education process. These data suggest that education is an NK cell-specific function of inhibitory MHC-I receptors.
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31
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Arming S, Wipfler D, Mayr J, Merling A, Vilas U, Schauer R, Schwartz-Albiez R, Vlasak R. The human Cas1 protein: a sialic acid-specific O-acetyltransferase? Glycobiology 2011; 21:553-64. [PMID: 20947662 PMCID: PMC7108626 DOI: 10.1093/glycob/cwq153] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Sialic acids are important sugars at the reducing end of glycoproteins and glycolipids. They are among many other functions involved in cell-cell interactions, host-pathogen recognition and the regulation of serum half-life of glycoproteins. An important modification of sialic acids is O-acetylation, which can alter or mask the biological properties of the parent sialic acid molecule. The nature of mammalian sialate-O-acetyltransferases (EC 2.3.1.45) involved in their biosynthesis is still unknown. We have identified the human CasD1 (capsule structure1 domain containing 1) gene as a candidate to encode the elusive enzyme. The human CasD1 gene encodes a protein with a serine-glycine-asparagine-histidine hydrolase domain and a hydrophobic transmembrane domain. Expression of the Cas1 protein tagged with enhanced green fluorescent protein in mammalian and insect cells directed the protein to the medial and trans-cisternae of the Golgi. Overexpression of the Cas1 protein in combination with α-N-acetyl-neuraminide α-2,8-sialyltransferase 1 (GD3 synthase) resulted in an up to 40% increased biosynthesis of 7-O-acetylated ganglioside GD3. By quantitative real-time polymerase chain reaction, we found up to 5-fold increase in CasD1 mRNA in tumor cells overexpressing O-Ac-GD3. CasD1-specific small interfering RNA reduced O-acetylation in tumor cells. These results suggest that the human Cas1 protein is directly involved in O-acetylation of α2-8-linked sialic acids.
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Affiliation(s)
- Sigrid Arming
- Department of Molecular Biology, University Salzburg, Austria
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32
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Held W, Kijima M, Angelov G, Bessoles S. The function of natural killer cells: education, reminders and some good memories. Curr Opin Immunol 2011; 23:228-33. [DOI: 10.1016/j.coi.2010.11.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 11/22/2010] [Accepted: 11/22/2010] [Indexed: 11/16/2022]
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33
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Tsai S, Hardison NE, James AH, Motsinger-Reif AA, Bischoff SR, Thames BH, Piedrahita JA. Transcriptional profiling of human placentas from pregnancies complicated by preeclampsia reveals disregulation of sialic acid acetylesterase and immune signalling pathways. Placenta 2010; 32:175-82. [PMID: 21183218 DOI: 10.1016/j.placenta.2010.11.014] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 10/09/2010] [Accepted: 11/19/2010] [Indexed: 02/08/2023]
Abstract
The placenta plays an important role as a regulator of fetal nutrition and growth throughout development and placental factors contribute to gestational abnormalities such as preeclampsia. This study describes the genome-wide gene expression profiles of a large (n = 60) set of human placentas in order to uncover gene expression patterns associated with preeclampsia. In addition to confirming changes in expression of soluble factors associated with preeclampsia such as sFLT1 (soluble fms-like tyrosine kinase-1), sENG (soluble endoglin), and INHA (inhibin alpha), we also find changes in immune-associated signaling pathways, offering a potential upstream explanation for the shallow trophoblast invasion and inadequate uterine remodeling typically observed in pathogenesis of preeclampsia. Notably, we also find evidence of preeclampsia-associated placental upregulation of sialic acid acetylesterase (SIAE), a gene functionally associated with autoimmune diseases.
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Affiliation(s)
- S Tsai
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
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34
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Surolia I, Pirnie SP, Chellappa V, Taylor KN, Cariappa A, Moya J, Liu H, Bell DW, Driscoll DR, Diederichs S, Haider K, Netravali I, Le S, Elia R, Dow E, Lee A, Freudenberg J, De Jager PL, Chretien Y, Varki A, MacDonald ME, Gillis T, Behrens TW, Bloch D, Collier D, Korzenik J, Podolsky DK, Hafler D, Murali M, Sands B, Stone JH, Gregersen PK, Pillai S. Functionally defective germline variants of sialic acid acetylesterase in autoimmunity. Nature 2010; 466:243-7. [PMID: 20555325 PMCID: PMC2900412 DOI: 10.1038/nature09115] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Accepted: 04/22/2010] [Indexed: 01/05/2023]
Abstract
Sialic acid acetylesterase (SIAE) is an enzyme that negatively regulates B lymphocyte antigen receptor signaling and is required for the maintenance of immunological tolerance in mice1, 2. Heterozygous loss-of-function germline rare variants and a homozygous defective polymorphic variant of SIAE were identified in 24/923 Caucasian subjects with relatively common autoimmune disorders and in 2/648 Caucasian controls. All heterozygous loss-of-function SIAE mutations tested were capable of functioning in a dominant negative manner. A homozygous secretion-defective polymorphic variant of SIAE was catalytically active, lacked the ability to function in a dominant negative manner, and was seen in 8 autoimmune subjects but in no control subjects. The Odds Ratio for inheriting defective SIAE alleles was 8.6 in all autoimmune subjects, 8.3 in subjects with rheumatoid arthritis, and 7.9 in subjects with type I diabetes. Functionally defective SIAE rare and polymorphic variants represent a strong genetic link to susceptibility in relatively common human autoimmune disorders.
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Affiliation(s)
- Ira Surolia
- Cancer Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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35
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Parker RB, Kohler JJ. Regulation of intracellular signaling by extracellular glycan remodeling. ACS Chem Biol 2010; 5:35-46. [PMID: 19968325 DOI: 10.1021/cb9002514] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The plasma membrane of eukaryotic cells is coated with carbohydrates. By virtue of their extracellular position and recognizable chemical features, cell surface glycans mediate many receptor-ligand interactions. Recently, mammalian extracellular hydrolytic enzymes have been shown to modify the structure of cell surface glycans and consequently alter their binding properties. These cell surface glycan remodeling events can cause rapid changes in critical signal transduction phenomena. This Review highlights recent studies on the roles of eukaryotic extracellular sialidases, sulfatases, and a deacetylase in regulation of intracellular signaling. We also describe possible therapies that target extracellular glycan remodeling processes and discuss the potential for new discoveries in this area.
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Affiliation(s)
- Randy B. Parker
- Division of Translational Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9185
| | - Jennifer J. Kohler
- Division of Translational Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9185
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36
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The follicular versus marginal zone B lymphocyte cell fate decision. Nat Rev Immunol 2009; 9:767-77. [PMID: 19855403 DOI: 10.1038/nri2656] [Citation(s) in RCA: 382] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bone marrow-derived B cells make an important cell fate choice to develop into either follicular B cells or marginal zone B cells in the spleen, which depends on signalling through the B cell receptor, Notch2, the receptor for B cell-activating factor and the canonical nuclear factor-kappaB pathway, as well as signals involved in the migration and anatomical retention of marginal zone B cells. Recent information discussed in this Review reconciles some of the controversies regarding the role of the B cell receptor in this cell fate decision and a clearer picture has also emerged regarding the anatomical location of ligands for Notch2 in the spleen. This cell fate decision could provide mechanistic insights that are relevant to other commitment events in lymphocytes.
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