1
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Jalloh S, Olejnik J, Berrigan J, Nisa A, Suder EL, Akiyama H, Lei M, Ramaswamy S, Tyagi S, Bushkin Y, Mühlberger E, Gummuluru S. CD169-mediated restrictive SARS-CoV-2 infection of macrophages induces pro-inflammatory responses. PLoS Pathog 2022; 18:e1010479. [PMID: 36279285 PMCID: PMC9632919 DOI: 10.1371/journal.ppat.1010479] [Citation(s) in RCA: 9] [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: 03/29/2022] [Revised: 11/03/2022] [Accepted: 10/06/2022] [Indexed: 11/06/2022] Open
Abstract
Exacerbated and persistent innate immune response marked by pro-inflammatory cytokine expression is thought to be a major driver of chronic COVID-19 pathology. Although macrophages are not the primary target cells of SARS-CoV-2 infection in humans, viral RNA and antigens in activated monocytes and macrophages have been detected in post-mortem samples, and dysfunctional monocytes and macrophages have been hypothesized to contribute to a protracted hyper-inflammatory state in COVID-19 patients. In this study, we demonstrate that CD169, a myeloid cell specific I-type lectin, facilitated ACE2-independent SARS-CoV-2 fusion and entry in macrophages. CD169-mediated SARS-CoV-2 entry in macrophages resulted in expression of viral genomic and subgenomic RNAs with minimal viral protein expression and no infectious viral particle release, suggesting a post-entry restriction of the SARS-CoV-2 replication cycle. Intriguingly this post-entry replication block was alleviated by exogenous ACE2 expression in macrophages. Restricted expression of viral genomic and subgenomic RNA in CD169+ macrophages elicited a pro-inflammatory cytokine expression (TNFα, IL-6 and IL-1β) in a RIG-I, MDA-5 and MAVS-dependent manner, which was suppressed by remdesivir treatment. These findings suggest that de novo expression of SARS-CoV-2 RNA in macrophages contributes to the pro-inflammatory cytokine signature and that blocking CD169-mediated ACE2 independent infection and subsequent activation of macrophages by viral RNA might alleviate COVID-19-associated hyperinflammatory response.
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Affiliation(s)
- Sallieu Jalloh
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Judith Olejnik
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, Massachusetts, United States of America
| | - Jacob Berrigan
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Annuurun Nisa
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
| | - Ellen L. Suder
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, Massachusetts, United States of America
| | - Hisashi Akiyama
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Maohua Lei
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Sita Ramaswamy
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Sanjay Tyagi
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
| | - Yuri Bushkin
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
| | - Elke Mühlberger
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, Massachusetts, United States of America
| | - Suryaram Gummuluru
- Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
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2
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Bensing BA, Stubbs HE, Agarwal R, Yamakawa I, Luong K, Solakyildirim K, Yu H, Hadadianpour A, Castro MA, Fialkowski KP, Morrison KM, Wawrzak Z, Chen X, Lebrilla CB, Baudry J, Smith JC, Sullam PM, Iverson TM. Origins of glycan selectivity in streptococcal Siglec-like adhesins suggest mechanisms of receptor adaptation. Nat Commun 2022; 13:2753. [PMID: 35585145 PMCID: PMC9117288 DOI: 10.1038/s41467-022-30509-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 04/26/2022] [Indexed: 11/22/2022] Open
Abstract
Bacterial binding to host receptors underlies both commensalism and pathogenesis. Many streptococci adhere to protein-attached carbohydrates expressed on cell surfaces using Siglec-like binding regions (SLBRs). The precise glycan repertoire recognized may dictate whether the organism is a strict commensal versus a pathogen. However, it is currently not clear what drives receptor selectivity. Here, we use five representative SLBRs and identify regions of the receptor binding site that are hypervariable in sequence and structure. We show that these regions control the identity of the preferred carbohydrate ligand using chimeragenesis and single amino acid substitutions. We further evaluate how the identity of the preferred ligand affects the interaction with glycoprotein receptors in human saliva and plasma samples. As point mutations can change the preferred human receptor, these studies suggest how streptococci may adapt to changes in the environmental glycan repertoire.
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Affiliation(s)
- Barbara A Bensing
- Division of Infectious Diseases, Veterans Affairs Medical Center, Department of Medicine, University of California, San Francisco, CA, USA
- the Northern California Institute for Research and Education, San Francisco, CA, 94121, USA
| | - Haley E Stubbs
- Graduate Program in Chemical and Physical Biology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Rupesh Agarwal
- University of Tennessee/Oak Ridge National Laboratory, Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6309, USA
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Izumi Yamakawa
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA
- School of Nursing, Belmont University, Nashville, TN, 37212, USA
| | - Kelvin Luong
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Kemal Solakyildirim
- Department of Chemistry, Erzincan Binali Yildirim University, Erzincan, 24100, Turkey
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Hai Yu
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Azadeh Hadadianpour
- Department of Microbiology, Pathology, and Immunology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Manuel A Castro
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Kevin P Fialkowski
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA
- College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
| | - KeAndreya M Morrison
- Department of Pharmacology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, 37208, USA
| | - Zdzislaw Wawrzak
- LS-CAT Synchrotron Research Center, Northwestern University, Argonne, IL, 60439, USA
| | - Xi Chen
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Carlito B Lebrilla
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Jerome Baudry
- Department of Biological Sciences, The University of Alabama in Huntsville, Huntsville, AL, 35899, USA
| | - Jeremy C Smith
- University of Tennessee/Oak Ridge National Laboratory, Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6309, USA
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Paul M Sullam
- Division of Infectious Diseases, Veterans Affairs Medical Center, Department of Medicine, University of California, San Francisco, CA, USA
- the Northern California Institute for Research and Education, San Francisco, CA, 94121, USA
| | - T M Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, 37232, USA.
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA.
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3
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Jalloh S, Olejnik J, Berrigan J, Nisa A, Suder EL, Akiyama H, Lei M, Tyagi S, Bushkin Y, Mühlberger E, Gummuluru S. CD169-mediated restrictive SARS-CoV-2 infection of macrophages induces pro-inflammatory responses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.03.29.486190. [PMID: 35378756 PMCID: PMC8978933 DOI: 10.1101/2022.03.29.486190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Exacerbated and persistent innate immune response marked by pro-inflammatory cytokine expression is thought to be a major driver of chronic COVID-19 pathology. Although macrophages are not the primary target cells of SARS-CoV-2 infection in humans, viral RNA and antigens in activated monocytes and macrophages have been detected in post-mortem samples, and dysfunctional monocytes and macrophages have been hypothesized to contribute to a protracted hyper-inflammatory state in COVID-19 patients. In this study, we demonstrate that CD169, a myeloid cell specific I-type lectin, facilitated ACE2-independent SARS-CoV-2 fusion and entry in macrophages. CD169- mediated SARS-CoV-2 entry in macrophages resulted in expression of viral genomic and sub-genomic (sg) RNAs with minimal viral protein expression and no infectious viral particle release, suggesting a post-entry restriction of the SARS-CoV-2 replication cycle. Intriguingly this post-entry replication block was alleviated by exogenous ACE2 expression in macrophages. Restricted expression of viral gRNA and sgRNA in CD169 + macrophages elicited a pro-inflammatory cytokine expression (TNFα, IL-6 and IL-1β) in a RIG-I, MDA-5 and MAVS-dependent manner, which was suppressed by remdesivir pre- treatment. These findings suggest that de novo expression of SARS-CoV-2 RNA in macrophages contributes to the pro-inflammatory cytokine signature and that blocking CD169-mediated ACE2 independent infection and subsequent activation of macrophages by viral RNA might alleviate COVID-19-associated hyperinflammatory response. Author Summary Over-exuberant production of pro-inflammatory cytokine expression by macrophages has been hypothesized to contribute to severity of COVID-19 disease. Molecular mechanisms that contribute to macrophage-intrinsic immune activation during SARS- CoV-2 infection are not fully understood. Here we show that CD169, a macrophage- specific sialic-acid binding lectin, facilitates abortive SARS-CoV-2 infection of macrophages that results in innate immune sensing of viral replication intermediates and production of proinflammatory responses. We identify an ACE2-independent, CD169- mediated endosomal viral entry mechanism that results in cytoplasmic delivery of viral capsids and initiation of virus replication, but absence of infectious viral production. Restricted viral replication in CD169 + macrophages and detection of viral genomic and sub-genomic RNAs by cytoplasmic RIG-I-like receptor family members, RIG-I and MDA5, and initiation of downstream signaling via the adaptor protein MAVS, was required for innate immune activation. These studies uncover mechanisms important for initiation of innate immune sensing of SARS-CoV-2 infection in macrophages, persistent activation of which might contribute to severe COVID-19 pathophysiology.
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Affiliation(s)
- Sallieu Jalloh
- Department of Microbiology, Boston University School of Medicine, Boston, MA, USA
| | - Judith Olejnik
- Department of Microbiology, Boston University School of Medicine, Boston, MA, USA
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA
| | - Jacob Berrigan
- Department of Microbiology, Boston University School of Medicine, Boston, MA, USA
| | - Annuurun Nisa
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Ellen L Suder
- Department of Microbiology, Boston University School of Medicine, Boston, MA, USA
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA
| | - Hisashi Akiyama
- Department of Microbiology, Boston University School of Medicine, Boston, MA, USA
| | - Maohua Lei
- Department of Microbiology, Boston University School of Medicine, Boston, MA, USA
| | - Sanjay Tyagi
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Yuri Bushkin
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Elke Mühlberger
- Department of Microbiology, Boston University School of Medicine, Boston, MA, USA
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA
| | - Suryaram Gummuluru
- Department of Microbiology, Boston University School of Medicine, Boston, MA, USA
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4
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D'Addio M, Frey J, Tacconi C, Commerford CD, Halin C, Detmar M, Cummings RD, Otto VI. Sialoglycans on lymphatic endothelial cells augment interactions with Siglec-1 (CD169) of lymph node macrophages. FASEB J 2021; 35:e22017. [PMID: 34699642 DOI: 10.1096/fj.202100300r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 09/30/2021] [Accepted: 10/12/2021] [Indexed: 12/20/2022]
Abstract
Cellular interactions between endothelial cells and macrophages regulate macrophage localization and phenotype, but the mechanisms underlying these interactions are poorly understood. Here we explored the role of sialoglycans on lymphatic endothelial cells (LEC) in interactions with macrophage-expressed Siglec-1 (CD169). Lectin-binding assays and mass spectrometric analyses revealed that LEC from human skin express more sialylated glycans than the corresponding blood endothelial cells. Higher amounts of sialylated and/or sulfated glycans on LEC than BEC were consistently observed in murine skin, lung and lymph nodes. The floor LEC of the subcapsular sinus (SCS) in murine lymph nodes (LN) displayed sialylated glycans at particularly high densities. The sialoglycans of LN LEC were strongly bound by Siglec-1. Such binding plays an important role in the localization of Siglec-1+ LN-SCS macrophages, as their numbers are strongly reduced in mice expressing a Siglec-1 mutant that is defective in sialoglycan binding. The residual Siglec-1+ macrophages are less proliferative and have a more anti-inflammatory phenotype. We propose that the densely clustered, sialylated glycans on the SCS floor LEC are a key component of the macrophage niche, providing anchorage for the Siglec-1+ LN-SCS macrophages.
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Affiliation(s)
- Marco D'Addio
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Jasmin Frey
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Carlotta Tacconi
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | | | - Cornelia Halin
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Michael Detmar
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Richard D Cummings
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Vivianne I Otto
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
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5
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A Novel Attenuated Enterovirus A71 Mutant with VP1-V238A,K244R Exhibits Reduced Efficiency of Cell Entry/Exit and Augmented Binding Affinity to Sulfated Glycans. J Virol 2021; 95:e0105521. [PMID: 34468173 PMCID: PMC8549518 DOI: 10.1128/jvi.01055-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Enterovirus A71 (EV-A71) is one of the major etiological agents of hand, foot, and mouth disease (HFMD), and infection occasionally leads to fatal neurological complications in children. However, only inactivated whole-virus vaccines against EV-A71 are commercially available in Mainland China. Furthermore, the mechanisms underlying the infectivity and pathogenesis of EV-A71 remain to be better understood. By adaptation of an EV-A71 B5 strain in monkey Vero cells in the presence of brilliant black BN (E151), an anti-EV-A71 agent, a double mutant with VP1-V238A,K244R emerged whose infection was enhanced by E151. The growth of the reverse genetics (RG) mutant RG/B5-VP1-V238A,K244R (RG/B5-AR) was promoted by E151 in Vero cells but inhibited in other human and murine cells, while its parental wild type, RG/B5-wt, was strongly prevented by E151 from infection in all tested cells. In the absence of E151, RG/B5-AR exhibited defective cell entry/exit, resulting in reduced viral transmission and growth in vitro. It had augmented binding affinity to sulfated glycans, cells, and tissue/organs, which probably functioned as decoys to restrict viral dissemination and infection. RG/B5-AR was also attenuated, with a 355 times higher 50% lethal dose (LD50) and a shorter timing of virus clearance than those of RG/B5-wt in suckling AG129 mice. However, it remained highly immunogenic in adult AG129 mice and protected their suckling mice from lethal EV-A71 challenges through maternal neutralizing antibodies. Overall, discovery of the attenuated mutant RG/B5-AR contributes to better understanding of virulence determinants of EV-A71 and to further development of novel vaccines against EV-A71. IMPORTANCE Enterovirus A71 (EV-A71) is highly contagious in children and has been responsible for thousands of deaths in Asia-Pacific region since the 1990s. Unfortunately, the virulence determinants and pathogenesis of EV-A71 are not fully clear. We discovered that a novel EV-A71 mutant, VP1-V238A,K244R, showed growth attenuation with reduced efficiency of cell entry/exit. In the Vero cell line, which has been approved for manufacturing EV-A71 vaccines, the growth defects of the mutant were compensated by a food dye, brilliant black BN. The mutant also showed augmented binding affinity to sulfated glycans and other cellular components, which probably restricted viral infection and dissemination. Therefore, it was virulence attenuated in a mouse model but still retained its immunogenicity. Our findings suggest the mutant as a promising vaccine candidate against EV-A71 infection.
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6
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Sytnyk V, Leshchyns'ka I, Schachner M. Neural glycomics: the sweet side of nervous system functions. Cell Mol Life Sci 2021; 78:93-116. [PMID: 32613283 PMCID: PMC11071817 DOI: 10.1007/s00018-020-03578-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 06/06/2020] [Accepted: 06/22/2020] [Indexed: 02/07/2023]
Abstract
The success of investigations on the structure and function of the genome (genomics) has been paralleled by an equally awesome progress in the analysis of protein structure and function (proteomics). We propose that the investigation of carbohydrate structures that go beyond a cell's metabolism is a rapidly developing frontier in our expanding knowledge on the structure and function of carbohydrates (glycomics). No other functional system appears to be suited as well as the nervous system to study the functions of glycans, which had been originally characterized outside the nervous system. In this review, we describe the multiple studies on the functions of LewisX, the human natural killer cell antigen-1 (HNK-1), as well as oligomannosidic and sialic (neuraminic) acids. We attempt to show the sophistication of these structures in ontogenetic development, synaptic function and plasticity, and recovery from trauma, with a view on neurodegeneration and possibilities to ameliorate deterioration. In view of clinical applications, we emphasize the need for glycomimetic small organic compounds which surpass the usefulness of natural glycans in that they are metabolically more stable, more parsimonious to synthesize or isolate, and more advantageous for therapy, since many of them pass the blood brain barrier and are drug-approved for treatments other than those in the nervous system, thus allowing a more ready access for application in neurological diseases. We describe the isolation of such mimetic compounds using not only Western NIH, but also traditional Chinese medical libraries. With this review, we hope to deepen the interests in this exciting field.
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Affiliation(s)
- Vladimir Sytnyk
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia.
| | - Iryna Leshchyns'ka
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Melitta Schachner
- Center for Neuroscience, Shantou University Medical College, 22 Xin Ling Road, Shantou, 515041, Guangdong, China
- Department of Cell Biology and Neuroscience, Keck Center for Collaborative Neuroscience, Rutgers University, 604 Allison Road, Piscataway, NJ, 08854, USA
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7
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Hane M, Chen DY, Varki A. Human-specific microglial Siglec-11 transcript variant has the potential to affect polysialic acid-mediated brain functions at a distance. Glycobiology 2020; 31:231-242. [PMID: 32845322 DOI: 10.1093/glycob/cwaa082] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 08/05/2020] [Accepted: 08/07/2020] [Indexed: 12/11/2022] Open
Abstract
CD33-related Siglecs are often found on innate immune cells and modulate their reactivity by recognition of sialic acid-based "self-associated molecular patterns" and signaling via intracellular tyrosine-based cytosolic motifs. Previous studies have shown that Siglec-11 specifically binds to the brain-enriched polysialic acid (polySia/PSA) and that its microglial expression in the brain is unique to humans. Furthermore, human microglial Siglec-11 exists as an alternate splice form missing the exon encoding the last (fifth) Ig-like C2-set domain of the extracellular portion of the protein, but little is known about the functional consequences of this variation. Here, we report that the recombinant soluble human microglial form of Siglec-11 (hSiglec-11(4D)-Fc) binds endogenous and immobilized polySia better than the tissue macrophage form (hSiglec-11(5D)-Fc) or the chimpanzee form (cSiglec-11(5D)-Fc). The Siglec-11 protein is also prone to aggregation, potentially influencing its ligand-binding ability. Additionally, Siglec-11 protein can be secreted in both intact and proteolytically cleaved forms. The microglial splice variant has reduced proteolytic release and enhanced incorporation into exosomes, a process that appears to be regulated by palmitoylation of cysteines in the cytosolic tail. Taken together, these data demonstrate that human brain specific microglial hSiglec-11(4D) has different molecular properties and can be released on exosomes and/or as proteolytic products, with the potential to affect polySia-mediated brain functions at a distance.
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Affiliation(s)
- Masaya Hane
- Departments of Medicine and Cellular & Molecular Medicine, Center for Academic Research and Training in Anthropogeny, Glycobiology Research and Training Center, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093, USA
| | - Dillon Y Chen
- Departments of Medicine and Cellular & Molecular Medicine, Center for Academic Research and Training in Anthropogeny, Glycobiology Research and Training Center, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093, USA
| | - Ajit Varki
- Departments of Medicine and Cellular & Molecular Medicine, Center for Academic Research and Training in Anthropogeny, Glycobiology Research and Training Center, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093, USA
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8
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Characterisation of the Dynamic Interactions between Complex
N
‐Glycans and Human CD22. Chembiochem 2019; 21:129-140. [DOI: 10.1002/cbic.201900295] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Indexed: 12/21/2022]
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9
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van Dinther D, Veninga H, Iborra S, Borg EGF, Hoogterp L, Olesek K, Beijer MR, Schetters STT, Kalay H, Garcia-Vallejo JJ, Franken KL, Cham LB, Lang KS, van Kooyk Y, Sancho D, Crocker PR, den Haan JMM. Functional CD169 on Macrophages Mediates Interaction with Dendritic Cells for CD8 + T Cell Cross-Priming. Cell Rep 2019; 22:1484-1495. [PMID: 29425504 DOI: 10.1016/j.celrep.2018.01.021] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/12/2017] [Accepted: 01/08/2018] [Indexed: 12/16/2022] Open
Abstract
Splenic CD169+ macrophages are located in the marginal zone to efficiently capture blood-borne pathogens. Here, we investigate the requirements for the induction of CD8+ T cell responses by antigens (Ags) bound by CD169+ macrophages. Upon Ag targeting to CD169+ macrophages, we show that BATF3-dependent CD8α+ dendritic cells (DCs) are crucial for DNGR-1-mediated cross-priming of CD8+ T cell responses. In addition, we demonstrate that CD169, a sialic acid binding lectin involved in cell-cell contact, preferentially binds to CD8α+ DCs and that Ag transfer to CD8α+ DCs and subsequent T cell activation is dependent on the sialic acid-binding capacity of CD169. Finally, functional CD169 mediates optimal CD8+ T cell responses to modified vaccinia Ankara virus infection. Together, these data indicate that the collaboration of CD169+ macrophages and CD8α+ DCs for the initiation of effective CD8+ T cell responses is facilitated by binding of CD169 to sialic acid containing ligands on CD8α+ DCs.
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Affiliation(s)
- Dieke van Dinther
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Henrike Veninga
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Salvador Iborra
- Immunobiology Laboratory, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
| | - Ellen G F Borg
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Leoni Hoogterp
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Katarzyna Olesek
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Marieke R Beijer
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Sjoerd T T Schetters
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Hakan Kalay
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Juan J Garcia-Vallejo
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - Kees L Franken
- Department of Immunohematology and Bloodtransfusion, LUMC, Leiden, the Netherlands
| | - Lamin B Cham
- Institute of Immunology, Medical Faculty, University Duisburg-Essen, 45122 Essen, Germany
| | - Karl S Lang
- Institute of Immunology, Medical Faculty, University Duisburg-Essen, 45122 Essen, Germany
| | - Yvette van Kooyk
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands
| | - David Sancho
- Immunobiology Laboratory, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
| | - Paul R Crocker
- Division of Cell Signalling and Immunology, University of Dundee, Dundee, UK
| | - Joke M M den Haan
- Cancer Center Amsterdam, Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, the Netherlands.
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10
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Biassoni R, Malnati MS. Human Natural Killer Receptors, Co-Receptors, and Their Ligands. ACTA ACUST UNITED AC 2019; 121:e47. [PMID: 30040219 DOI: 10.1002/cpim.47] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In the last 20 years, the study of human natural killer (NK) cells has moved from the first molecular characterizations of very few receptor molecules to the identification of a plethora of receptors displaying surprisingly divergent functions. We have contributed to the description of inhibitory receptors and their signaling pathways, important in fine regulation in many cell types, but unknown until their discovery in the NK cells. Inhibitory function is central to regulating NK-mediated cytolysis, with different molecular structures evolving during speciation to assure its persistence. More recently, it has become possible to characterize the NK triggering receptors mediating natural cytotoxicity, unveiling the existence of a network of cellular interactions between effectors of both natural and adaptive immunity. This unit reviews the contemporary history of molecular studies of receptors and ligands involved in NK cell function, characterizing the ligands of the triggering receptor and the mechanisms for finely regulating their expression in pathogen-infected or tumor cells. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Roberto Biassoni
- IRCCS Istituto Giannina Gaslini, Laboratory of Molecular Medicine, Genova, Italy
| | - Mauro S Malnati
- IRCCS Ospedale San Raffaele, Unit of Human Virology, Division of Immunology, Transplantation and Infectious Diseases, Milan, Italy
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11
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Erikson E, Wratil PR, Frank M, Ambiel I, Pahnke K, Pino M, Azadi P, Izquierdo-Useros N, Martinez-Picado J, Meier C, Schnaar RL, Crocker PR, Reutter W, Keppler OT. Mouse Siglec-1 Mediates trans-Infection of Surface-bound Murine Leukemia Virus in a Sialic Acid N-Acyl Side Chain-dependent Manner. J Biol Chem 2015; 290:27345-27359. [PMID: 26370074 DOI: 10.1074/jbc.m115.681338] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Indexed: 01/21/2023] Open
Abstract
Siglec-1 (sialoadhesin, CD169) is a surface receptor on human cells that mediates trans-enhancement of HIV-1 infection through recognition of sialic acid moieties in virus membrane gangliosides. Here, we demonstrate that mouse Siglec-1, expressed on the surface of primary macrophages in an interferon-α-responsive manner, captures murine leukemia virus (MLV) particles and mediates their transfer to proliferating lymphocytes. The MLV infection of primary B-cells was markedly more efficient than that of primary T-cells. The major structural protein of MLV particles, Gag, frequently co-localized with Siglec-1, and trans-infection, primarily of surface-bound MLV particles, efficiently occurred. To explore the role of sialic acid for MLV trans-infection at a submolecular level, we analyzed the potential of six sialic acid precursor analogs to modulate the sialylated ganglioside-dependent interaction of MLV particles with Siglec-1. Biosynthetically engineered sialic acids were detected in both the glycolipid and glycoprotein fractions of MLV producer cells. MLV released from cells carrying N-acyl-modified sialic acids displayed strikingly different capacities for Siglec-1-mediated capture and trans-infection; N-butanoyl, N-isobutanoyl, N-glycolyl, or N-pentanoyl side chain modifications resulted in up to 92 and 80% reduction of virus particle capture and trans-infection, respectively, whereas N-propanoyl or N-cyclopropylcarbamyl side chains had no effect. In agreement with these functional analyses, molecular modeling indicated reduced binding affinities for non-functional N-acyl modifications. Thus, Siglec-1 is a key receptor for macrophage/lymphocyte trans-infection of surface-bound virions, and the N-acyl side chain of sialic acid is a critical determinant for the Siglec-1/MLV interaction.
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Affiliation(s)
- Elina Erikson
- Institute of Medical Virology, National Reference Center for Retroviruses, University of Frankfurt, 60596 Frankfurt am Main, Germany,; Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Paul R Wratil
- the Institut für Laboratoriumsmedizin, Klinische Chemie und Pathobiochemie, Charité Universitätsmedizin Berlin, 12200 Berlin, Germany
| | | | - Ina Ambiel
- Institute of Medical Virology, National Reference Center for Retroviruses, University of Frankfurt, 60596 Frankfurt am Main, Germany
| | - Katharina Pahnke
- Organic Chemistry, Department of Chemistry, Faculty of Sciences, University of Hamburg, 20146 Hamburg, Germany
| | - Maria Pino
- the AIDS Research Institute IrsiCaixa, Institut d'Investigatio en Ciencies de la Salut Germans Trias I Pujol, Universitat Autonoma de Barcelona, 08916 Barcelona, Spain
| | - Parastoo Azadi
- the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - Nuria Izquierdo-Useros
- the AIDS Research Institute IrsiCaixa, Institut d'Investigatio en Ciencies de la Salut Germans Trias I Pujol, Universitat Autonoma de Barcelona, 08916 Barcelona, Spain
| | - Javier Martinez-Picado
- the AIDS Research Institute IrsiCaixa, Institut d'Investigatio en Ciencies de la Salut Germans Trias I Pujol, Universitat Autonoma de Barcelona, 08916 Barcelona, Spain,; the Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
| | - Chris Meier
- Organic Chemistry, Department of Chemistry, Faculty of Sciences, University of Hamburg, 20146 Hamburg, Germany
| | - Ronald L Schnaar
- Departments of Pharmacology and Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21218
| | - Paul R Crocker
- College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Werner Reutter
- the Institut für Laboratoriumsmedizin, Klinische Chemie und Pathobiochemie, Charité Universitätsmedizin Berlin, 12200 Berlin, Germany
| | - Oliver T Keppler
- Institute of Medical Virology, National Reference Center for Retroviruses, University of Frankfurt, 60596 Frankfurt am Main, Germany,; Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Germany,.
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12
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Johnson QR, Lindsay RJ, Petridis L, Shen T. Investigation of Carbohydrate Recognition via Computer Simulation. Molecules 2015; 20:7700-18. [PMID: 25927900 PMCID: PMC6272577 DOI: 10.3390/molecules20057700] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 04/15/2015] [Accepted: 04/15/2015] [Indexed: 12/11/2022] Open
Abstract
Carbohydrate recognition by proteins, such as lectins and other (bio)molecules, can be essential for many biological functions. Recently, interest has arisen due to potential protein and drug design and future bioengineering applications. A quantitative measurement of carbohydrate-protein interaction is thus important for the full characterization of sugar recognition. We focus on the aspect of utilizing computer simulations and biophysical models to evaluate the strength and specificity of carbohydrate recognition in this review. With increasing computational resources, better algorithms and refined modeling parameters, using state-of-the-art supercomputers to calculate the strength of the interaction between molecules has become increasingly mainstream. We review the current state of this technique and its successful applications for studying protein-sugar interactions in recent years.
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Affiliation(s)
- Quentin R Johnson
- UT-ORNL Graduate School of Genome Science and Technology, Knoxville, TN 37996, USA.
| | - Richard J Lindsay
- Department of Biochemistry and Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
| | - Loukas Petridis
- Center for Molecular Biophysics, Oak Ridge National Lab, Oak Ridge, TN 37830, USA.
| | - Tongye Shen
- Department of Biochemistry and Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
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13
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Kijewski SDG, Gummuluru S. A mechanistic overview of dendritic cell-mediated HIV-1 trans infection: the story so far. Future Virol 2015; 10:257-269. [PMID: 26213560 PMCID: PMC4508676 DOI: 10.2217/fvl.15.2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Despite progress in antiretroviral therapy, HIV-1 rebound after cessation of antiretroviral therapy suggests that establishment of long-term cellular reservoirs of virus is a significant barrier to functional cure. There is considerable evidence that dendritic cells (DCs) play an important role in systemic virus dissemination. Although productive infection of DCs is inefficient, DCs capture HIV-1 and transfer-captured particles to CD4+ T cells, a mechanism of DC-mediated HIV-1 trans infection. Recent findings suggest that DC-mediated trans infection of HIV-1 is dependent on recognition of GM3, a virus-particle-associated host-derived ligand, by CD169 expressed on DCs. In this review, we describe mechanisms of DC-mediated HIV-1 trans infection and discuss specifically the role of CD169 in establishing infection in CD4+ T cells.
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Affiliation(s)
- Suzanne DG Kijewski
- Department of Microbiology, Boston University School of Medicine, Boston, MA 02118, USA
| | - Suryaram Gummuluru
- Department of Microbiology, Boston University School of Medicine, Boston, MA 02118, USA
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14
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Pröpster JM, Yang F, Ernst B, Allain FHT, Schubert M. Functional Siglec lectin domains from soluble expression in the cytoplasm of Escherichia coli. Protein Expr Purif 2015; 109:14-22. [PMID: 25623398 DOI: 10.1016/j.pep.2015.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 01/09/2015] [Accepted: 01/19/2015] [Indexed: 01/25/2023]
Abstract
Siglecs (sialic acid-binding immunoglobulin-like lectins) are a family of mammalian cell-surface receptors that are involved in cell-cell interactions and signaling functions, primarily expressed on cells of the immune system. Key to their function is their specific binding of distinct sialylated glycan ligands mediated via an N-terminal carbohydrate recognition (lectin) domain. Studies concerning the molecular basis of their individual carbohydrate specificities are rare due to the absence of suitable recombinant expression methods for producing these disulfide-containing proteins in sufficient quantities required for their in-depth in vitro characterization. We established an efficient E. coli-based expression and purification method for Siglec lectin domains, utilizing the trxB gor suppressor strain Rosetta-gami B (DE3) in which proper folding with intact disulfide bonds was achieved in the cytoplasm. The approach is demonstrated for human Siglec-7, -8 and -9 lectin domains and works equally well for expression in nutrient-rich (LB) or minimal growth medium, allowing stable-isotope labeling for NMR studies. The recombinant proteins were properly folded as proven by 2D (1)H-(15)N HSQC NMR spectroscopy and by thermal unfolding followed by CD spectroscopy, and functionally active as confirmed by monitoring ligand binding using NMR titration experiments. Our method enables efficient production of homogeneous and active protein samples in milligram quantities. Its implementation will significantly enhance future structure-function studies of this important class of immune-modulating receptors and will support a variety of applications including screening for natural and synthetic ligands or the development of fluorescently-labeled molecular tools for glycan ligand detection or flow-cytometric cell sorting.
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Affiliation(s)
- Johannes M Pröpster
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Fan Yang
- Institute of Molecular Pharmacy, Pharmacenter, University of Basel, CH-4056 Basel, Switzerland; Department of Molecular & Medical Pharmacology, David Geffen School of Medicine at UCLA, CA 90095, USA(1)
| | - Beat Ernst
- Institute of Molecular Pharmacy, Pharmacenter, University of Basel, CH-4056 Basel, Switzerland
| | - Frédéric H-T Allain
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland.
| | - Mario Schubert
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland; Department of Molecular Biology, University of Salzburg, A-5020 Salzburg, Austria(1).
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15
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Abstract
Exosomes are lipid nanovesicles released following fusion of the endosoma limiting membrane with the plasma membrane; however, their fate in lymphoid organs after their release remains controversial. We determined that sialoadhesin (CD169; Siglec-1) is required for the capture of B cell-derived exosomes via their surface-expressed α2,3-linked sialic acids. Exosome-capturing macrophages were present in the marginal zone of the spleen and in the subcapsular sinus of the lymph node. In vitro assays performed on spleen and lymph node sections confirmed that exosome binding to CD169 was not solely due to preferential fluid flow to these areas. Although the circulation half-life of exosomes in blood of wild-type and CD169(-/-) mice was similar, exosomes displayed altered distribution in CD169(-/-) mice, with exosomes freely accessing the outer marginal zone rim of SIGN-R1(+) macrophages and F4/80(+) red pulp macrophages. In the lymph node, exosomes were not retained in the subcapsular sinus of CD169(-/-) mice but penetrated deeper into the paracortex. Interestingly, CD169(-/-) mice demonstrated an enhanced response to antigen-pulsed exosomes. This is the first report of a role for CD169 in the capture of exosomes and its potential to mediate the immune response to exosomal antigen.
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16
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Porcine, murine and human sialoadhesin (Sn/Siglec-1/CD169): portals for porcine reproductive and respiratory syndrome virus entry into target cells. J Gen Virol 2013; 94:1955-1960. [DOI: 10.1099/vir.0.053082-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Porcine sialoadhesin (pSn; a sialic acid-binding lectin) and porcine CD163 (pCD163) are molecules that facilitate infectious entry of porcine reproductive and respiratory syndrome virus (PRRSV) into alveolar macrophages. In this study, it was shown that murine Sn (mSn) and human Sn (hSn), like pSn, can promote PRRSV infection of pCD163-expressing cells. Intact sialic acid-binding domains are crucial, since non-sialic acid-binding mutants of pSn, mSn and hSn did not promote infection. Endodomain-deletion mutants of pSn, mSn and hSn promoted PRRSV infection less efficiently, but also showed markedly reduced expression levels, making further research into the potential role of the Sn endodomain in PRRSV receptor activity necessary. These data further complement our knowledge on Sn as an important PRRSV receptor, and suggest – in combination with other published data – that species differences in the main PRRSV entry mediators Sn and CD163 do not account for the strict host species specificity displayed by the virus.
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17
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Interferon-inducible mechanism of dendritic cell-mediated HIV-1 dissemination is dependent on Siglec-1/CD169. PLoS Pathog 2013; 9:e1003291. [PMID: 23593001 PMCID: PMC3623718 DOI: 10.1371/journal.ppat.1003291] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 02/21/2013] [Indexed: 01/12/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) interactions with myeloid dendritic cells (DCs) can result in virus dissemination to CD4+ T cells via a trans infection pathway dependent on virion incorporation of the host cell derived glycosphingolipid (GSL), GM3. The mechanism of DC-mediated trans infection is extremely efficacious and can result in infection of multiple CD4+ T cells as these cells make exploratory contacts on the DC surface. While it has long been appreciated that activation of DCs with ligands that induce type I IFN signaling pathway dramatically enhances DC-mediated T cell trans infection, the mechanism by which this occurs has remained unclear until now. Here, we demonstrate that the type I IFN-inducible Siglec-1, CD169, is the DC receptor that captures HIV in a GM3-dependent manner. Selective downregulation of CD169 expression, neutralizing CD169 function, or depletion of GSLs from virions, abrogated DC-mediated HIV-1 capture and trans infection, while exogenous expression of CD169 in receptor-naïve cells rescued GSL-dependent capture and trans infection. HIV-1 particles co-localized with CD169 on DC surface immediately following capture and subsequently within non-lysosomal compartments that redistributed to the DC – T cell infectious synapses upon initiation of T cell contact. Together, these findings describe a novel mechanism of pathogen parasitization of host encoded cellular recognition machinery (GM3 – CD169 interaction) for DC-dependent HIV dissemination. Dendritic cells (DCs) are one of the initial cellular targets of HIV-1 and can play a crucial role in determining the course of virus infection in vivo. While sentinel functions of DCs are essential for establishment of an antiviral state, HIV-1 can subvert DC function for its dissemination. One of the mechanisms by which DCs can mediate virus spread is via the trans infection pathway whereby DCs capture HIV-1 particles and retain them in an infectious state without getting infected, and pass these infectious particles to CD4+ T cells upon initiation of cellular contacts. In this report, we demonstrate that expression of Siglec-1or CD169, on DC surface is responsible for capture of HIV-1 particles by binding the ganglioside, GM3, present in the virion lipid bilayer. This interaction between CD169 and GM3 targets captured virus particles to non-degradative compartments and resulted in retention of virus particle infectivity within DCs. Upon initiation of T cell contacts with virus-laden DCs, HIV-1 particles were trafficked to the DC – T synaptic junctions and transferred to T cells for establishment of productive infection. These studies define a novel host-encoded receptor – ligand interaction that drives HIV-1 dissemination and can be used for development of novel anti-viral therapeutics.
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18
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Abstract
CD22 is a 140-kDa member of the Siglec family of cell surface proteins that is expressed by most mature B-cell lineages. As a co-receptor of the B-cell receptor (BCR), it is known to contribute to the sensitive control of the B-cell response to antigen. Cross-linking of CD22 and the BCR by antigen triggers the phosphorylation of CD22, which leads to activation of signaling molecules such as phosphatases. Signal transduction pathways involving CD22 have been explored in a number of mouse models, some of which have provided evidence that in the absence of functional CD22, B cells have a "hyperactivated" phenotype, and suggest that loss of CD22 function could contribute to the pathogenesis of autoimmune diseases. Modulating CD22 activity has therefore been suggested as a possible therapeutic approach to such diseases. For example, the novel CD22-targeting monoclonal antibody epratuzumab is currently under investigation as a treatment for the connective tissue disorder systemic lupus erythematosus (SLE).
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Affiliation(s)
- Thomas Dörner
- Charité University Medicine Berlin, CC12, Dept. Medicine/Rheumatology and Clinical Immunology and German Rheumatism Research Center Berlin (DRFZ), Berlin, Germany.
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19
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Kidder D, Richards HE, Ziltener HJ, Garden OA, Crocker PR. Sialoadhesin ligand expression identifies a subset of CD4+Foxp3- T cells with a distinct activation and glycosylation profile. THE JOURNAL OF IMMUNOLOGY 2013; 190:2593-602. [PMID: 23408841 DOI: 10.4049/jimmunol.1201172] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Sialoadhesin (Sn) is a sialic acid-binding Ig-like lectin expressed selectively on macrophage subsets. In a model of experimental autoimmune encephalomyelitis, Sn interacted with sialylated ligands expressed selectively on CD4(+)Foxp3(+) regulatory T cells (Tregs) and inhibited their proliferation. In this study, we examined the induction of Sn ligands (SnL) on all splenic CD4(+) T cells following in vitro activation. Most CD4(+) Tregs strongly upregulated SnL, whereas only a small subset of ~20% CD4(+)Foxp3(-) T cells (effector T cells [Teffs]) upregulated SnL. SnL(+) Teffs displayed higher levels of activation markers CD25 and CD69, exhibited increased proliferation, and produced higher amounts of IL-2 and IFN-γ than corresponding SnL(-) Teffs. Coculture of activated Teffs with Sn(+) macrophages or Sn(+) Chinese hamster ovary cells resulted in increased cell death, suggesting a regulatory role for Sn-SnL interactions. The key importance of α2,3-sialylation in SnL expression was demonstrated by increased binding of α2,3-linkage-specific Maackia amurensis lectin, increased expression of α2,3-sialyltransferase ST3GalVI, and loss of SnL following treatment with an α2,3-linkage-specific sialidase. The induction of SnL on activated CD4(+) T cells was dependent on N-glycan rather than O-glycan biosynthesis and independent of the mucin-like molecules CD43 and P-selectin glycoprotein ligand-1, previously implicated in Sn interactions. Induction of ligands on CD4(+)Foxp3(-) Teffs was also observed in vivo using the New Zealand Black × New Zealand White F1 murine model of spontaneous lupus and SnL levels on Teffs correlated strongly with the degree of proteinuria. Collectively, these data indicate that SnL is a novel marker of activated CD4(+) Teffs that are implicated in the pathogenesis of autoimmune diseases.
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Affiliation(s)
- Dana Kidder
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
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20
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Heikema AP, Jacobs BC, Horst-Kreft D, Huizinga R, Kuijf ML, Endtz HP, Samsom JN, van Wamel WJB. Siglec-7 specifically recognizes Campylobacter jejuni strains associated with oculomotor weakness in Guillain-Barré syndrome and Miller Fisher syndrome. Clin Microbiol Infect 2012; 19:E106-12. [PMID: 23173866 DOI: 10.1111/1469-0691.12073] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 10/12/2012] [Accepted: 10/12/2012] [Indexed: 11/26/2022]
Abstract
Due to molecular mimicry, Campylobacter jejuni lipo-oligosaccharides can induce a cross-reactive antibody response to nerve gangliosides, which leads to Guillain-Barré syndrome (GBS). Cross-reactive antibodies to ganglioside GQ1b are strongly associated with oculomotor weakness in GBS and its variant, Miller Fisher syndrome (MFS). Antigen recognition is a crucial first step in the induction of a cross-reactive antibody response, and it has been shown that GQ1b-like epitopes expressed on the surface of C. jejuni are recognized by sialic acid-binding immunoglobulin-like lectin-7 (Siglec-7). We aimed to determine the epitope specificity of C. jejuni binding to Siglec-7, and correlate the outcome to disease symptoms in GBS and MFS patients. Using a well-defined GBS/MFS-associated C. jejuni strain collection, which included three sialic acid knockout strains, we found that Siglec-7 exclusively binds to C. jejuni strains that express terminal disialylated ganglioside mimics. When serological and diagnostic patient records were correlated with the Siglec-7-binding properties, we observed an association between Siglec-7 binding and the presence of anti-GQ1b antibodies in patient serum. In addition, Siglec-7 binding was associated with oculomotor weakness in GBS and MFS patients. Lipo-oligosaccharide-specific binding of C. jejuni to Siglec-7 may be an initiating event in immune recognition and presentation, and lead to anti-GQ1b antibody production and the development of ocular weakness in GBS or MFS.
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Affiliation(s)
- A P Heikema
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands.
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21
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Klaas M, Oetke C, Lewis LE, Erwig LP, Heikema AP, Easton A, Willison HJ, Crocker PR. Sialoadhesin promotes rapid proinflammatory and type I IFN responses to a sialylated pathogen, Campylobacter jejuni. THE JOURNAL OF IMMUNOLOGY 2012; 189:2414-22. [PMID: 22851711 DOI: 10.4049/jimmunol.1200776] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sialoadhesin (Sn) is a macrophage (Mφ)-restricted receptor that recognizes sialylated ligands on host cells and pathogens. Although Sn is thought to be important in cellular interactions of Mφs with cells of the immune system, the functional consequences of pathogen engagement by Sn are unclear. As a model system, we have investigated the role of Sn in Mφ interactions with heat-killed Campylobacter jejuni expressing a GD1a-like, sialylated glycan. Compared to Sn-expressing bone marrow-derived macrophages (BMDM) from wild-type mice, BMDM from mice either deficient in Sn or expressing a non-glycan-binding form of Sn showed greatly reduced phagocytosis of sialylated C. jejuni. This was accompanied by a strong reduction in MyD88-dependent secretion of TNF-α, IL-6, IL-12, and IL-10. In vivo studies demonstrated that functional Sn was required for rapid TNF-α and IFN-β responses to i.v.-injected sialylated C. jejuni. Bacteria were captured within minutes after i.v. injection and were associated with Mφs in both liver and spleen. In the spleen, IFN-β-reactive cells were localized to Sn⁺ Mφs and other cells in the red pulp and marginal zone. Together, these studies demonstrate that Sn plays a key role in capturing sialylated pathogens and promoting rapid proinflammatory cytokine and type I IFN responses.
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Affiliation(s)
- Mariliis Klaas
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
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22
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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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23
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Klaas M, Crocker PR. Sialoadhesin in recognition of self and non-self. Semin Immunopathol 2012; 34:353-64. [PMID: 22450957 DOI: 10.1007/s00281-012-0310-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 03/05/2012] [Indexed: 11/28/2022]
Abstract
The immune system is tightly regulated to maintain an appropriate balance between immune activation and tolerance. Macrophages play a key role in this process since they express many pathogen recognition molecules as well as receptors for 'self'. Sialoadhesin is a major macrophage receptor that specifically recognizes sialic acid, an abundant component of host glycoconjugates but which can also be found on several human pathogens. In recent years, several studies have demonstrated that sialoadhesin can contribute to the uptake and processing of sialylated pathogens as well as playing an important role in regulating inflammatory and autoimmune responses via recognition of self.
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Affiliation(s)
- Mariliis Klaas
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee, UK
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24
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Sun Y, Senger K, Baginski TK, Mazloom A, Chinn Y, Pantua H, Hamidzadeh K, Ramani SR, Luis E, Tom I, Sebrell A, Quinones G, Ma Y, Mukhyala K, Sai T, Ding J, Haley B, Shadnia H, Kapadia SB, Gonzalez LC, Hass PE, Zarrin AA. Evolutionarily conserved paired immunoglobulin-like receptor α (PILRα) domain mediates its interaction with diverse sialylated ligands. J Biol Chem 2012; 287:15837-50. [PMID: 22396535 DOI: 10.1074/jbc.m111.286633] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Paired immunoglobulin-like receptor (PILR) α is an inhibitory receptor that recognizes several ligands, including mouse CD99, PILR-associating neural protein, and Herpes simplex virus-1 glycoprotein B. The physiological function(s) of interactions between PILRα and its cellular ligands are not well understood, as are the molecular determinants of PILRα/ligand interactions. To address these uncertainties, we sought to identify additional PILRα ligands and further define the molecular basis for PILRα/ligand interactions. Here, we identify two novel PILRα binding partners, neuronal differentiation and proliferation factor-1 (NPDC1), and collectin-12 (COLEC12). We find that sialylated O-glycans on these novel PILRα ligands, and on known PILRα ligands, are compulsory for PILRα binding. Sialylation-dependent ligand recognition is also a property of SIGLEC1, a member of the sialic acid-binding Ig-like lectins. SIGLEC1 Ig domain shares ∼22% sequence identity with PILRα, an identity that includes a conserved arginine localized to position 97 in mouse and human SIGLEC1, position 133 in mouse PILRα and position 126 in human PILRα. We observe that PILRα/ligand interactions require conserved PILRα Arg-133 (mouse) and Arg-126 (human), in correspondence with a previously reported requirement for SIGLEC1 Arg-197 in SIGLEC1/ligand interactions. Homology modeling identifies striking similarities between PILRα and SIGLEC1 ligand binding pockets as well as at least one set of distinctive interactions in the galactoxyl-binding site. Binding studies suggest that PILRα recognizes a complex ligand domain involving both sialic acid and protein motif(s). Thus, PILRα is evolved to engage multiple ligands with common molecular determinants to modulate myeloid cell functions in anatomical settings where PILRα ligands are expressed.
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Affiliation(s)
- Yonglian Sun
- Department of Immunology, Genentech, South San Francisco, California 94080, USA
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25
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Characterization of the specific interaction between sialoadhesin and sialylated Campylobacter jejuni lipooligosaccharides. Infect Immun 2010; 78:3237-46. [PMID: 20421384 DOI: 10.1128/iai.01273-09] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Campylobacter jejuni-induced Guillain-Barré syndrome (GBS), molecular mimicry between C. jejuni lipooligosaccharide (LOS) and host gangliosides leads to the production of cross-reactive antibodies directed against the peripheral nerves of the host. Currently, the presence of surface exposed sialylated LOS in C. jejuni is the single known bacterial pathogenesis factor associated with the development of GBS. Using a unique, well-characterized strain collection, we demonstrate that GBS-associated C. jejuni strains bind preferentially to sialoadhesin (Sn, Siglec-1, or CD169), a sialic acid receptor found on a subset of macrophages. In addition, using a whole-cell enzyme-linked immunosorbent assay (ELISA), C. jejuni strains with sialylated LOS bound exclusively to soluble Sn. Mass spectrometry revealed that binding was sialic acid-linkage specific with a preference for alpha(2,3)-linked sialic acid attached to the terminal galactose of the LOS chain as seen in the gangliosides GD1a, GM1b, and GM3. This molecular interaction was also related to functional consequences as a GBS-associated C. jejuni strain that bound Sn in a whole-cell ELISA adhered to surface-expressed Sn of Sn-transfected CHO cells but was unable to adhere to wild-type CHO cells. Moreover, a sialic acid-negative mutant of the same C. jejuni strain was unable to bind Sn-transfected CHO cells. This is the first report of the preferential binding of GBS-associated C. jejuni strains to the Sn immune receptor (P = 0.014). Moreover, because this binding is dependent on sialylated LOS, the main pathogenic factor in GBS progression, the present findings bring us closer to unraveling the mechanisms that lead to formation of cross-reactive antibodies in GBS disease.
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Van Breedam W, Delputte PL, Van Gorp H, Misinzo G, Vanderheijden N, Duan X, Nauwynck HJ. Porcine reproductive and respiratory syndrome virus entry into the porcine macrophage. J Gen Virol 2010; 91:1659-67. [PMID: 20410315 DOI: 10.1099/vir.0.020503-0] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) emerged in the late 1980s and rapidly became one of the most significant viral pathogens in the swine industry. In vivo, the virus shows a very narrow cell tropism and targets specific subsets of porcine macrophages. The entry of PRRSV into its host cell is the first crucial step in infection and has been the focus of many fundamental studies. This review provides a comprehensive overview of the current knowledge on PRRSV entry into the porcine macrophage, covering virus binding, internalization and genome release, and integrates these findings into a general model of the entry process.
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Affiliation(s)
- Wander Van Breedam
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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27
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Abstract
Siglecs have emerged as an important family of immunomodulatory glycan-binding proteins that can bind sialoside ligands both on the same cell surface, in cis, and on other cells, in trans. Expression of siglecs varies among a variety of immune cells, and tools to probe siglecs on these cells are crucial to understanding their function. In designing synthetic ligands, competition by cis ligands requires the use of multivalency to achieve sufficient avidity to stably bind siglecs on native cells. This chapter describes the use of multivalent ligands to probe cell surfaces, as well as to investigate ligand binding to recombinant siglecs.
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Affiliation(s)
- Mary K O'Reilly
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, USA
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Abdu-Allah HHM, Watanabe K, Hayashizaki K, Takaku C, Tamanaka T, Takematsu H, Kozutsumi Y, Tsubata T, Ishida H, Kiso M. Potent small molecule mouse CD22-inhibitors: exploring the interaction of the residue at C-2 of sialic acid scaffold. Bioorg Med Chem Lett 2009; 19:5573-5. [PMID: 19720531 DOI: 10.1016/j.bmcl.2009.08.044] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 08/08/2009] [Accepted: 08/12/2009] [Indexed: 10/20/2022]
Abstract
Our previous study revealed that compound 1 (9-(4'-hydroxy-4-biphenyl)acetamido-9-deoxy-Neu5Gcalpha2-6GalOMP) has the most promising affinity for mCD22. Replacing the subterminal galactose residue of 1 with benzyl or biphenylmethyl as aglycone led to 38- and 20-fold higher potency, respectively. This discovery represents a new direction in inhibitor design suitable for pharmaceutical development.
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Affiliation(s)
- Hajjaj H M Abdu-Allah
- Department of Applied Bio-organic Chemistry, The United Graduate School of Agricultural Sciences, Gifu University, Gifu 501-1193, Japan.
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Lewis(x) and alpha2,3-sialyl glycans and their receptors TAG-1, Contactin, and L1 mediate CD24-dependent neurite outgrowth. J Neurosci 2009; 29:6677-90. [PMID: 19458237 DOI: 10.1523/jneurosci.4361-08.2009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Although carbohydrates have been implicated in cell interactions in the nervous system, the molecular bases of their functions have remained largely obscure. Here, we show that promotion or inhibition of neurite outgrowth of cerebellar or dorsal root ganglion neurons, respectively, induced by the mucin-type adhesion molecule CD24 depends on alpha2,3-linked sialic acid and Lewis(x) present on glia-specific CD24 glycoforms. Alpha2,3-sialyl residues of CD24 bind to a structural motif in the first fibronectin type III domain of the adhesion molecule L1. Following the observation that the adhesion molecules TAG-1 and Contactin show sequence homologies with fucose-specific lectins, we obtained evidence that TAG-1 and Contactin mediate Lewis(x)-dependent CD24-induced effects on neurite outgrowth. Thus, L1, TAG-1, and Contactin function as lectin-like neuronal receptors. Their cis interactions with neighboring adhesion molecules, e.g., Caspr1 and Caspr2, and with their triggered signal transduction pathways elicit cell type-specific promotion or inhibition of neurite outgrowth induced by glial CD24 in a glycan-dependent trans interaction.
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Chen GY, Tang J, Zheng P, Liu Y. CD24 and Siglec-10 selectively repress tissue damage-induced immune responses. Science 2009; 323:1722-5. [PMID: 19264983 PMCID: PMC2765686 DOI: 10.1126/science.1168988] [Citation(s) in RCA: 582] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Patten recognition receptors, which recognize pathogens or components of injured cells (danger), trigger activation of the innate immune system. Whether and how the host distinguishes between danger- versus pathogen-associated molecular patterns remains unresolved. We report that CD24-deficient mice exhibit increased susceptibility to danger- but not pathogen-associated molecular patterns. CD24 associates with high mobility group box 1, heat shock protein 70, and heat shock protein 90; negatively regulates their stimulatory activity; and inhibits nuclear factor kappaB (NF-kappaB) activation. This occurs at least in part through CD24 association with Siglec-10 in humans or Siglec-G in mice. Our results reveal that the CD24-Siglec G pathway protects the host against a lethal response to pathological cell death and discriminates danger- versus pathogen-associated molecular patterns.
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Affiliation(s)
- Guo-Yun Chen
- Division of Immunotherapy, Department of Surgery, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Jie Tang
- Institute of Biophysics, Chinese Academy of Science, Beijing, China
| | - Pan Zheng
- Division of Immunotherapy, Department of Surgery, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
- Division of Immunotherapy, Department of Pathology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Yang Liu
- Division of Immunotherapy, Department of Surgery, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
- Division of Immunotherapy, Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
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31
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Biassoni R. Human natural killer receptors, co-receptors, and their ligands. CURRENT PROTOCOLS IN IMMUNOLOGY 2009; Chapter 14:14.10.1-14.10.40. [PMID: 19235767 DOI: 10.1002/0471142735.im1410s84] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In the last 20 years, the study of human natural killer (NK) cells has moved from the first molecular characterizations of very few receptor molecules to the identification of a plethora of receptors displaying surprisingly divergent functions. Our laboratory has contributed to the description of inhibitory receptors and their signaling pathways, important in fine regulation in many cell types, but unknown until their discovery in the NK cells. Inhibitory function is central to regulating NK-mediated cytolysis, with different molecular structures evolving during speciation to assure its persistence. Only in the last ten years has it become possible to characterize the NK triggering receptors mediating natural cytotoxicity, leading to an appreciation of the existence of a cellular interaction network between effectors of both natural and adaptive immunity. This report reviews the contemporary history of molecular studies of receptors and ligands involved in NK cell function, characterizing the ligands of the triggering receptor and the mechanisms for finely regulating their expression in pathogen-infected or tumor cells.
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Affiliation(s)
- Roberto Biassoni
- Instituto Giannina Gaslini, Laboratory of Molecular Medicine, Genova, Italy
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Abdu-Allah HHM, Tamanaka T, Yu J, Zhuoyuan L, Sadagopan M, Adachi T, Tsubata T, Kelm S, Ishida H, Kiso M. Design, synthesis, and structure-affinity relationships of novel series of sialosides as CD22-specific inhibitors. J Med Chem 2008; 51:6665-81. [PMID: 18841881 DOI: 10.1021/jm8000696] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Sialosides incorporating substituted amides or amines at 9-position of sialic acid moiety have been synthesized and evaluated as CD22 inhibitors. Several derivatives exhibited inhibitory potency in sub- to low micromolar range (e. g., 8o, 9d, 9g, and 9k showed IC 50 values 0.40, 0.47, 0.24, and 0.23 microM, respectively, for hCD22, while 8p, 8q, and 9f, showed IC 50 values 1.70, 2.90, and 4.10 microM, respectively, for mCD22). The most significant result was the strongly enhanced affinity of 9g and 9k containing 9-(2' or 4'-hydroxy-4-biphenyl) methylamino substituents (600-fold more potent for hCD22 than the corresponding 9-hydroxy derivative; 7a). Molecular modeling study was carried out to get some insights into the molecular basis of CD22 inhibition. To the best of our knowledge, this is the first systematic structure-affinity relationship study on inhibition of CD22.
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Affiliation(s)
- Hajjaj H M Abdu-Allah
- Department of Applied Bio-organic Chemistry, The United Graduate School of Agricultural Sciences, Gifu University, Gifu 501-1193, Japan
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Wang J, Shiratori I, Satoh T, Lanier LL, Arase H. An essential role of sialylated O-linked sugar chains in the recognition of mouse CD99 by paired Ig-like type 2 receptor (PILR). THE JOURNAL OF IMMUNOLOGY 2008; 180:1686-93. [PMID: 18209065 DOI: 10.4049/jimmunol.180.3.1686] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The paired Ig-like type 2 receptor (PILR), which comprises both inhibitory and activating isoforms, is well conserved among most mammalians. The inhibitory PILRalpha possesses an ITIM in its cytoplasmic domain, whereas the activating PILRbeta does not have an ITIM but transduces activating signals by associating with the ITAM-bearing DAP12 adapter molecule. Both mouse PILRalpha and PILRbeta recognize mouse CD99, which is broadly expressed on various cells, including lymphocytes, and is involved in the regulation of immune responses. We herein report that sialylated O-linked sugar chains on CD99 are essential for the recognition by PILR. Mutations of one of two O-glycosylation sites on CD99 significantly reduced recognition of CD99 by the activating PILRbeta, whereas recognition by the inhibitory PILRalpha was not affected. In contrast, mutations of both O-glycosylation sites on CD99 completely abrogated the recognition by both PILRalpha and PILRbeta. PILR did not recognize CD99 treated with neuraminidase, and CD99 expressed on cells transfected with core 2 beta-1,6-N-acetylglucosaminyltransferase was not recognized by PILR. NK cells expressing endogenous activating PILRbeta receptors mediated cytotoxicity against cells expressing wild-type CD99 but not cells expressing mutant CD99 that lacked O-glycosylation sites. These findings indicate that sialylated O-linked sugar structures on CD99 play an important role in the recognition of PILR.
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Affiliation(s)
- Jing Wang
- Department of Immunochemistry, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka, Japan
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Walker JA, Smith KGC. Dependence of surface monoclonal antibody binding on dynamic changes in FcgammaRIIb expression. Immunology 2008; 124:412-8. [PMID: 18217946 PMCID: PMC2440835 DOI: 10.1111/j.1365-2567.2007.02791.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Receptors for the Fc region of immunoglobulin G (FcgammaRs) are expressed on a broad range of haematopoietic cell types and are responsible for regulating antibody production and linking the humoral and effector responses. In response to a number of stimuli, such as cytokine signals or inflammation, FcgammaR expression at the cell surface is dynamically regulated. On B cells, we observed what appeared to be a correlation between CD22 expression and FcgammaRIIb expression when the latter was varied in a number of models. Further investigation revealed that this was specific to a particular anti-CD22 monoclonal antibody, which appeared to require stabilization by interaction with FcgammaRIIb for optimal binding to CD22. Since alterations in the regulation of FcgammaR expression are important in controlling immune responses and have been associated with a number of immune-mediated disease states, we suggest that it might be prudent to confirm the expression of cell surface markers by two independent methods. Furthermore, because the efficacy of therapeutic antibodies may depend upon their interaction with FcgammaRs, our results are relevant to their design and assessment.
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Affiliation(s)
- Jennifer A Walker
- Department of Medicine, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge, UK.
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35
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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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36
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Royer B, Soares DC, Barlow PN, Bontrop RE, Roll P, Robaglia-Schlupp A, Blancher A, Levasseur A, Cau P, Pontarotti P, Szepetowski P. Molecular evolution of the human SRPX2 gene that causes brain disorders of the Rolandic and Sylvian speech areas. BMC Genet 2007; 8:72. [PMID: 17942002 PMCID: PMC2151080 DOI: 10.1186/1471-2156-8-72] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Accepted: 10/18/2007] [Indexed: 12/11/2022] Open
Abstract
Background The X-linked SRPX2 gene encodes a Sushi Repeat-containing Protein of unknown function and is mutated in two disorders of the Rolandic/Sylvian speech areas. Since it is linked to defects in the functioning and the development of brain areas for speech production, SRPX2 may thus have participated in the adaptive organization of such brain regions. To address this issue, we have examined the recent molecular evolution of the SRPX2 gene. Results The complete coding region was sequenced in 24 human X chromosomes from worldwide populations and in six representative nonhuman primate species. One single, fixed amino acid change (R75K) has been specifically incorporated in human SRPX2 since the human-chimpanzee split. The R75K substitution occurred in the first sushi domain of SRPX2, only three amino acid residues away from a previously reported disease-causing mutation (Y72S). Three-dimensional structural modeling of the first sushi domain revealed that Y72 and K75 are both situated in the hypervariable loop that is usually implicated in protein-protein interactions. The side-chain of residue 75 is exposed, and is located within an unusual and SRPX-specific protruding extension to the hypervariable loop. The analysis of non-synonymous/synonymous substitution rate (Ka/Ks) ratio in primates was performed in order to test for positive selection during recent evolution. Using the branch models, the Ka/Ks ratio for the human branch was significantly different (p = 0.027) from that of the other branches. In contrast, the branch-site tests did not reach significance. Genetic analysis was also performed by sequencing 9,908 kilobases (kb) of intronic SRPX2 sequences. Despite low nucleotide diversity, neither the HKA (Hudson-Kreitman-Aguadé) test nor the Tajima's D test reached significance. Conclusion The R75K human-specific variation occurred in an important functional loop of the first sushi domain of SRPX2, indicating that this evolutionary mutation may have functional importance; however, positive selection for R75K could not be demonstrated. Nevertheless, our data contribute to the first understanding of molecular evolution of the human SPRX2 gene. Further experiments are now required in order to evaluate the possible consequences of R75K on SRPX2 interactions and functioning.
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Affiliation(s)
- Barbara Royer
- INSERM UMR 491, Université de la Méditerranée, 13385 Marseille, Cedex 5, France.
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Cao Z, Qiu J, Domeniconi M, Hou J, Bryson JB, Mellado W, Filbin MT. The inhibition site on myelin-associated glycoprotein is within Ig-domain 5 and is distinct from the sialic acid binding site. J Neurosci 2007; 27:9146-54. [PMID: 17715351 PMCID: PMC6672207 DOI: 10.1523/jneurosci.2404-07.2007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Myelin-associated glycoprotein (MAG) is a potent inhibitor of axonal regeneration. It contains five Ig-like domains and is a sialic binding protein. Previously, we showed that the sialic acid binding site on MAG maps to arginine 118 in Ig domain 1 (Kelm et al., 1994). However, sialic acid binding was neither necessary nor sufficient for MAG to bring about inhibition of neurite outgrowth. Consistent with this, we now map a distinct inhibition site on MAG to Ig domain 5 (Ig-5). We show that when a truncated form of MAG missing Ig domains 1 and 2 is expressed by Chinese hamster ovary (CHO) cells, it does not bind sialic acid, but still inhibits neurite outgrowth almost as effectively as full-length MAG. To determine whether the inhibition site mapped to Ig-3, Ig-4, or Ig-5, we made chimeric molecules of various combinations of these three MAG Ig domains fused to Ig domains from another Ig family member, sialoadhesin (Sn), which also binds to sialic acid in the same linkage as MAG. The MAG-Sn molecules were expressed in CHO cells and all contained five Ig domains and were able to bind sialic acid. However, only the chimeric molecules containing MAG Ig-5 inhibited neurite outgrowth. Furthermore, peptides corresponding to sequences in MAG Ig-5, but not Ig-4 or Sn Ig-5, are able to block inhibition of neurite outgrowth by both wild-type MAG and CNS myelin. We conclude that the inhibition site on MAG is carried by Ig domain 5 and that this site is distinct from the sialic-acid binding site.
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Affiliation(s)
- Zixuan Cao
- The Department of Biological Sciences, Hunter College, City University of New York, New York, New York 10021
| | - Jin Qiu
- The Department of Biological Sciences, Hunter College, City University of New York, New York, New York 10021
| | - Marco Domeniconi
- The Department of Biological Sciences, Hunter College, City University of New York, New York, New York 10021
| | - Jianwei Hou
- The Department of Biological Sciences, Hunter College, City University of New York, New York, New York 10021
| | - J. Barney Bryson
- The Department of Biological Sciences, Hunter College, City University of New York, New York, New York 10021
| | - Wilfredo Mellado
- The Department of Biological Sciences, Hunter College, City University of New York, New York, New York 10021
| | - Marie T. Filbin
- The Department of Biological Sciences, Hunter College, City University of New York, New York, New York 10021
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Delputte PL, Van Breedam W, Delrue I, Oetke C, Crocker PR, Nauwynck HJ. Porcine arterivirus attachment to the macrophage-specific receptor sialoadhesin is dependent on the sialic acid-binding activity of the N-terminal immunoglobulin domain of sialoadhesin. J Virol 2007; 81:9546-50. [PMID: 17567703 PMCID: PMC1951444 DOI: 10.1128/jvi.00569-07] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The sialic acid-binding lectin sialoadhesin (Sn) is a macrophage-restricted receptor for porcine reproductive and respiratory syndrome virus (PRRSV). To investigate the importance of pSn sialic acid-binding activity for PRRSV infection, an R(116)-to-E mutation was introduced in the predicted sialic acid-binding domain of pSn, resulting in a mutant, pSn(RE), that could not bind sialic acids. PSn, but not pSn(RE), allowed PRRSV binding and internalization. These data show that the sialic acid-binding activity of pSn is essential for PRRSV attachment to pSn and thus identifies the variable, N-terminal domain of Sn as a PRRSV binding domain.
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Affiliation(s)
- Peter L Delputte
- Laboratory of Virology, Department Virology, Parasitology, and Immunology, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
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Zaccai NR, May AP, Robinson RC, Burtnick LD, Crocker PR, Brossmer R, Kelm S, Jones EY. Crystallographic and in Silico Analysis of the Sialoside-binding Characteristics of the Siglec Sialoadhesin. J Mol Biol 2007; 365:1469-79. [PMID: 17137591 DOI: 10.1016/j.jmb.2006.10.084] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 10/06/2006] [Accepted: 10/24/2006] [Indexed: 11/27/2022]
Abstract
The Siglec family of receptors mediates cell-surface interactions through recognition of sialylated glycoconjugates. Previously reported structures of the N-terminal domain of the Siglec sialoadhesin (SnD1) in complex with various sialic acid analogs revealed the structural template for sialic acid binding. To characterize further the carbohydrate-binding properties, we have determined the crystal structures of SnD1 in the absence of ligand, and in complex with 2-benzyl-Neu5NPro and 2-benzyl-Neu5NAc. These structures reveal that SnD1 undergoes very few structural changes on ligand binding and detail how two novel classes of sialic acid analogs bind, one of which unexpectedly can induce Siglec dimerization. In conjunction with in silico analysis, this set of structures informs us about the design of putative ligands with enhanced binding affinities and specificities to different Siglecs, and provides data with which to test the effectiveness of different computational drug design protocols.
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Affiliation(s)
- Nathan R Zaccai
- CR-UK Receptor Structure Research Group, Division of Structural Biology, The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Headington, Oxford OX3 7BN, UK.
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40
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Rapoport EM, Pazynina GV, Sablina MA, Crocker PR, Bovin NV. Probing sialic acid binding Ig-like lectins (siglecs) with sulfated oligosaccharides. BIOCHEMISTRY (MOSCOW) 2006; 71:496-504. [PMID: 16732727 DOI: 10.1134/s0006297906050051] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Soluble siglecs-1, -4, -5, -6, -7, -8, -9, and -10 were probed with polyacrylamide glycoconjugates in which: 1) the Neu5Ac residue was substituted by a sulfate group (Su); 2) glycoconjugates contained both Su and Neu5Ac; 3) sialoglycoconjugates contained a tyrosine-O-sulfate residue. It was shown that sulfate derivatives of LacNAc did not bind siglecs-1, -4, -5, -6, -7, -8, -9, and -10; binding of 6'-O-Su-LacNAc to siglec-8 was stronger than binding of 3'SiaLacNAc. The relative affinity of 3'-O-Su-TF binding to siglecs-1, -4, and -8 was similar to that of 3'SiaTF. 3'-O-Su-Le(c) displayed two-fold weaker binding to siglec-1 and siglec-4 than 3'SiaLe(c). The interaction of soluble siglecs with sulfated oligosaccharides containing sialic acid was also studied. It was shown that siglecs-1, -4, -5, -6, -7, -9, and -10 did not interact with these compounds; binding of 6-O-Su-3'SiaLacNAc and 6-O-Su-3'SiaTF to siglec-8 was weaker than that of the corresponding sulfate-free sialoside probes. Siglec-8 displayed affinity to 6'-O-Su-LacNAc and 6'-O-Su-SiaLe(x), and defucosylation of the latter compound led to an increase in the binding. Sialoside probes containing tyrosine-O-sulfate residue did not display increased affinity to siglecs-1 and -5 compared with glycoconjugates containing only sialoside. Cell-bound siglecs-1, -5, -7, and -9 did not interact with 6-O-Su-3'SiaLacNAc, whereas the sulfate-free probe 3'SiaLacNAc demonstrated binding. In contrast, the presence of sulfate in 6-O-Su-6'SiaLacNAc did not affect binding of the sialoside probe to siglecs. 6'-O-Su-SiaLe(x) displayed affinity to cell-bound siglecs-1 and -5; its isomer 6-O-Su-SiaLe(x) bound more strongly to siglecs-1, -5, and -9 than SiaLe(x).
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Affiliation(s)
- E M Rapoport
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
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Abstract
CD45 has been recognized as an important player in regulating signalling in lymphocytes. However, compared with tyrosine kinases, phosphatases are still poorly understood in terms of the details of their specificity and regulation. Here, the recent progress in understanding the biology of the first recognized receptor tyrosine phosphatase, CD45, is reviewed.
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Affiliation(s)
- Nick Holmes
- Division of Immunology, Department of Pathology, Cambridge University, UK.
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Mättö M, Nuutinen UM, Ropponen A, Myllykangas K, Pelkonen J. CD45RA and RO isoforms have distinct effects on cytokine- and B-cell-receptor-mediated signalling in human B cells. Scand J Immunol 2005; 61:520-8. [PMID: 15963046 DOI: 10.1111/j.1365-3083.2005.01624.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The common leucocyte antigen, CD45, is widely expressed on the surface of lymphocytes. In T and B cells, CD45 has an important role in the early events of receptor signalling. However, the role of various CD45 isoforms in B-cell receptor (BCR)- and cytokine-induced signalling and proliferation is still unclear. In the present study, we establish two follicular lymphoma cell lines expressing either CD45RA (HF28RA) or CD45R0 (HF28R0) isoforms. It was observed that the two isoforms had distinct effects on BCR- or cytokine-induced cellular proliferation. BCR stimulation significantly increased the proliferation of HF28R0 cells, in contrast to a decreased proliferation of HF28RA cells. Moreover, proliferation of HF28R0 cells significantly increased after the addition of interleukin-2 (IL-2), IL-4, IL-6, IL-10, IL-12, IL-13, IL-15, interferon-gamma and tumour necrosis factor-alpha cytokines, whereas most of these cytokines significantly inhibited the proliferation of HF28RA cells. In addition, the cell lines had their individual cytokine mRNA expression profiles after BCR stimulation. We also analysed the effect of CD45 isoforms on intracellular signalling after BCR stimulation. It was found out that the kinetics of ERK1/2 MAP kinase phosphorylation was clearly faster in HF28R0 than in HF28RA cells. The phosphorylation of other analysed MAP kinases or PTKs was very similar in the cell lines.
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Affiliation(s)
- M Mättö
- Department of Clinical Microbiology, University of Kuopio, Kuopio, Finland.
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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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Schwardt O, Gao G, Visekruna T, Rabbani S, Gassmann E, Ernst B. Substrate Specificity and Preparative Use of Recombinant Rat ST3Gal III. J Carbohydr Chem 2004. [DOI: 10.1081/car-120030021] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Bukrinsky JT, St Hilaire PM, Meldal M, Crocker PR, Henriksen A. Complex of sialoadhesin with a glycopeptide ligand. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2004; 1702:173-9. [PMID: 15488769 DOI: 10.1016/j.bbapap.2004.08.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 07/13/2004] [Accepted: 08/20/2004] [Indexed: 11/21/2022]
Abstract
Sialoadhesin is a sialic acid-binding immunoglobulin-like lectin (Siglec), expressed on subsets of macrophages. It is a model system for Siglec receptor-mediated cell surface interactions through binding of sialylated glycoconjugates. The N-terminal sialoadhesin domain can mediate sialic acid-binding on its own. The structure of this domain has been determined in complex with a sialic acid-containing heptapeptide, (Ala-Gly-His-Thr(Neu5Ac)-Trp-Gly-His). The affinity of sialoadhesin for this ligand is four times higher than the affinity for the natural linkage 2,3'-sialyllactose. The structure of the glycopeptide complex suggests strategies for ligand optimization and provides possible explanations for the observed differences in specificities among the Siglecs.
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Affiliation(s)
- Jens T Bukrinsky
- Department of Chemistry, The Carlsberg Laboratory, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
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Delputte PL, Nauwynck HJ. Porcine arterivirus infection of alveolar macrophages is mediated by sialic acid on the virus. J Virol 2004; 78:8094-101. [PMID: 15254181 PMCID: PMC446125 DOI: 10.1128/jvi.78.15.8094-8101.2004] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Recently, we showed that porcine sialoadhesin (pSn) mediates internalization of the arterivirus porcine reproductive and respiratory syndrome virus (PRRSV) in alveolar macrophages (Vanderheijden et al., J. Virol. 77:8207-8215, 2003). In rodents and humans, sialoadhesin, or Siglec-1, has been described as a macrophage-restricted molecule and to specifically bind sialic acid moieties. In the current study, we investigated whether pSn is a sialic acid binding protein and, whether so, whether this property is important for its function as a PRRSV receptor. Using untreated and neuraminidase-treated sheep erythrocytes, we showed that pSn binds sialic acid. Furthermore, pSn-specific monoclonal antibody 41D3, which blocks PRRSV infection, inhibited this interaction. PRRSV attachment to and infection of porcine alveolar macrophages (PAM) were both shown to be dependent on the presence of sialic acid on the virus: neuraminidase treatment of virus but not of PAM blocked infection and reduced attachment. Enzymatic removal of all N-linked glycans on the virus with N-glycosidase F reduced PRRSV infection, while exclusive removal of nonsialylated N-linked glycans of the high-mannose type with endoglycosidase H had no significant effect. Free sialyllactose and sialic acid containing (neo)glycoproteins reduced infection, while lactose and (neo)glycoproteins devoid of sialic acids had no significant effect. Studies with linkage-specific neuraminidases and lectins indicated that alpha2-3- and alpha2-6-linked sialic acids on the virion are important for PRRSV infection of PAM. From these results, we conclude that pSn is a sialic acid binding lectin and that interactions between sialic acid on the PRRS virion and pSn are essential for PRRSV infection of PAM.
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Kalovidouris SA, Blixt O, Nelson A, Vidal S, Turnbull WB, Paulson JC, Stoddart JF. Chemically defined sialoside scaffolds for investigation of multivalent interactions with sialic acid binding proteins. J Org Chem 2004; 68:8485-93. [PMID: 14575475 DOI: 10.1021/jo030203g] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Four glycodendrons and a glycocluster were synthesized from carbohydrate building blocks to form paucivalent (di- to tetravalent) structures of controlled scaffold architectures. Enzymatic sialylation of the functionalized cluster and dendrons, terminated in lactose residues, generated a library of paucivalent synthetic sialosides displaying sialic acids with different dispositions. These newly constructed bioactive sialic acid-based structures were differentially recognized by sialoadhesin, a mammalian macrophage sialic acid binding protein. The binding of the sialosides to sialoadhesin was evaluated by an enzyme-linked immunosorbant assay to investigate the complementarity of scaffold structure and binding to sialoadhesin. Modulating the interaction between sialoadhesin and its sialic acid ligands has important implications in immunobiology.
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Affiliation(s)
- Stacey A Kalovidouris
- California NanoSystems Institute and the Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095, USA
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Vanderheijden N, Delputte PL, Favoreel HW, Vandekerckhove J, Van Damme J, van Woensel PA, Nauwynck HJ. Involvement of sialoadhesin in entry of porcine reproductive and respiratory syndrome virus into porcine alveolar macrophages. J Virol 2003; 77:8207-15. [PMID: 12857889 PMCID: PMC165228 DOI: 10.1128/jvi.77.15.8207-8215.2003] [Citation(s) in RCA: 214] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2003] [Accepted: 05/06/2003] [Indexed: 11/20/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) shows a very restricted tropism for cells of the monocyte/macrophage lineage. It enters cells via receptor-mediated endocytosis. A monoclonal antibody (MAb) that is able to block PRRSV infection of porcine alveolar macrophages (PAM) and that recognizes a 210-kDa protein (p210) was described previously (MAb41D3) (X. Duan, H. Nauwynck, H. Favoreel, and M. Pensaert, J. Virol. 72:4520-4523, 1998). In the present study, the p210 protein was purified from PAM by immunoaffinity using MAb41D3 and was subjected to internal peptide sequencing after tryptic digestion. Amino acid sequence identities ranging from 56 to 91% with mouse sialoadhesin, a macrophage-restricted receptor, were obtained with four p210 peptides. Using these peptide data, the full p210 cDNA sequence (5,193 bp) was subsequently determined. It shared 69 and 78% amino acid identity, respectively, with mouse and human sialoadhesins. Swine (PK-15) cells resistant to viral entry were transfected with the cloned p210 cDNA and inoculated with European or American PRRSV strains. Internalized virus particles were detected only in PK-15 cells expressing the recombinant sialoadhesin, demonstrating that this glycoprotein mediated uptake of both types of strains. However, nucleocapsid disintegration, like that observed in infected Marc-145 cells as a result of virus uncoating after fusion of the virus with the endocytic vesicle membrane, was not observed, suggesting a block in the fusion process. The ability of porcine sialoadhesin to mediate endocytosis was demonstrated by specific internalization of MAb41D3 into PAM. Altogether, these results show that sialoadhesin is involved in the entry process of PRRSV in PAM.
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Affiliation(s)
- Nathalie Vanderheijden
- Laboratory of Virology, Faculty of Veterinary Medicine, Flanders Interuniversity Institute of Biotechnology (VIB), 5830 AA Boxmeer, The Netherlands
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Halkes KM, St Hilaire PM, Crocker PR, Meldal M. Glycopeptides as oligosaccharide mimics: high affinity sialopeptide ligands for sialoadhesin from combinatorial libraries. JOURNAL OF COMBINATORIAL CHEMISTRY 2003; 5:18-27. [PMID: 12523830 DOI: 10.1021/cc0200641] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two different sialic acid containing glycopeptide (sialopeptide) libraries were synthesized using the portion mixing method and ladder synthesis. The libraries were attached via an IMP spacer and a photolabile linker to PEGA(1900) resin in order to facilitate rapid and unambiguous structural analysis of hits by MALDI-TOFMS. One library contained a lactamized sialic acid moiety at the N terminus of a pentapeptide, while a second library displayed a sialic acid residue at the center of a heptapeptide. The sialopeptide libraries were screened against the recombinant binding domain (SnD1) of a sialic acid binding Ig-like protein, sialoadhesin (Siglec-1). No ligands were identified from the lactamized sialic acid library, underscoring the importance of the carboxylic acid moiety for binding. Screening of the second gave few distinct hits (approximately 0.03% of library) with a high consensus. The high-affinity ligands contained, in most cases, a WG motif following the sialylated Thr. The strength of binding of selected ligands was determined by surface plasmon resonance. The best sialopeptide ligand, WLLT(Sa)WGT, exhibited micromolar affinity of SnD1; >10 times the affinity of SnD1 to 3'-sialyl lactose.
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Affiliation(s)
- Koen M Halkes
- Carlsberg Laboratory, Center for Solid-Phase Combinatorial Chemistry, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
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50
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Rughetti A, Biffoni M, Pierelli L, Rahimi H, Bonanno G, Barachini S, Pellicciotta I, Napoletano C, Pescarmona E, Del Nero A, Pignoloni P, Frati L, Nuti M. Regulated expression of MUC1 epithelial antigen in erythropoiesis. Br J Haematol 2003; 120:344-52. [PMID: 12542497 DOI: 10.1046/j.1365-2141.2003.04038.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
MUC1 is a large surface glycoprotein expressed by epithelial cells, which is overexpressed and aberrantly glycosylated in carcinomas. MUC1 is involved in epithelial cell interactions and appears to function as a signal-transducing molecule. The finding that MUC1 can also be expressed in the haematopoietic lineages prompted us to further investigate the possible function(s) of this molecule in haematopoietic cells. In bone marrow differentiating cells, MUC1 was strongly and selectively expressed during erythropoiesis; it was also weakly expressed during megakaryocytopoiesis and granulomonocytopoiesis; however, no correlation between MUC1 and differentiation marker expression was observed in these lineages. In vitro CD34+ cells, induced towards erythroid differentiation, acquired MUC1 transiently, while expressing increasing levels of the lineage marker glycophorin A. MUC1 was absent in the circulating erythrocytes. During erythropoiesis, MUC1 expression was transcriptionally regulated and the molecule underwent phosphorylation. To investigate the possible role of MUC1 during erythropoiesis, we studied the ability of MUC1 to act as ligand for cell-cell interaction. The sialylated MUC1 glycoforms selectively expressed on erythroid cells were able to bind the macrophage-restricted molecule sialoadhesin. These results suggest that MUC1 can function as a cross-talk molecule between the erythroblasts and the surrounding cells during erythropoiesis.
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Affiliation(s)
- Aurelia Rughetti
- Department of Experimental Medicine and Pathology, University La Sapienza, Italy
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