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Fischer S, Stegmann F, Gnanapragassam VS, Lepenies B. From structure to function – Ligand recognition by myeloid C-type lectin receptors. Comput Struct Biotechnol J 2022; 20:5790-5812. [DOI: 10.1016/j.csbj.2022.10.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/14/2022] [Accepted: 10/14/2022] [Indexed: 11/29/2022] Open
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2
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Valle-Argos B, Chiodin G, Bryant DJ, Taylor J, Lemm E, Duriez PJ, Rock PJ, Strefford JC, Forconi F, Burack RW, Packham G, Stevenson FK. DC-SIGN binding to mannosylated B-cell receptors in follicular lymphoma down-modulates receptor signaling capacity. Sci Rep 2021; 11:11676. [PMID: 34083646 PMCID: PMC8175722 DOI: 10.1038/s41598-021-91112-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 05/20/2021] [Indexed: 12/13/2022] Open
Abstract
In follicular lymphoma (FL), surface immunoglobulin (sIg) carries mandatory N-glycosylation sites in the variable regions, inserted during somatic hypermutation. These glycosylation sites are tumor-specific, indicating a critical function in FL. Added glycan unexpectedly terminates at high mannose (Mann) and confers capability for sIg-mediated interaction with local macrophage-expressed DC-SIGN lectin resulting in low-level activation of upstream B-cell receptor signaling responses. Here we show that despite being of low-level, DC-SIGN induces a similar downstream transcriptional response to anti-IgM in primary FL cells, characterized by activation of pathways associated with B-cell survival, proliferation and cell-cell communication. Lectin binding was also able to engage post-transcriptional receptor cross-talk pathways since, like anti-IgM, DC-SIGN down-modulated cell surface expression of CXCR4. Importantly, pre-exposure of a FL-derived cell line expressing sIgM-Mann or primary FL cells to DC-SIGN, which does not block anti-IgM binding, reversibly paralyzed the subsequent Ca2+ response to anti-IgM. These novel findings indicate that modulation of sIg function occurs in FL via lectin binding to acquired mannoses. The B-cell receptor alternative engagement described here provides two advantages to lymphoma cells: (i) activation of signaling, which, albeit of low-level, is sufficient to trigger canonical lymphoma-promoting responses, and (ii) protection from exogenous antigen by paralyzing anti-IgM-induced signaling. Blockade of this alternative engagement could offer a new therapeutic strategy.
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MESH Headings
- Calcium/metabolism
- Calcium Signaling
- Cell Adhesion Molecules/genetics
- Cell Adhesion Molecules/metabolism
- Cell Line, Tumor
- Gene Expression Regulation, Neoplastic
- Glycosylation
- Humans
- Immunoglobulin M/immunology
- Lectins, C-Type/genetics
- Lectins, C-Type/metabolism
- Lymphoma, Follicular/genetics
- Lymphoma, Follicular/immunology
- Lymphoma, Follicular/metabolism
- Protein Binding
- Receptors, Antigen, B-Cell/metabolism
- Receptors, CXCR4/metabolism
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Signal Transduction
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Affiliation(s)
- Beatriz Valle-Argos
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Giorgia Chiodin
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Dean J Bryant
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Joe Taylor
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Elizabeth Lemm
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Patrick J Duriez
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Philip J Rock
- Pathology Department, University of Rochester Medical Center, NY, USA
| | - Jonathan C Strefford
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Francesco Forconi
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Richard W Burack
- Pathology Department, University of Rochester Medical Center, NY, USA
| | - Graham Packham
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK.
| | - Freda K Stevenson
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK.
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Rahimi N. C-type Lectin CD209L/L-SIGN and CD209/DC-SIGN: Cell Adhesion Molecules Turned to Pathogen Recognition Receptors. BIOLOGY 2020; 10:1. [PMID: 33375175 PMCID: PMC7822156 DOI: 10.3390/biology10010001] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 12/19/2022]
Abstract
C-type lectin CD209/DC-SIGN and CD209L/L-SIGN proteins are distinct cell adhesion and pathogen recognition receptors that mediate cellular interactions and recognize a wide range of pathogens, including viruses such as SARS, SARS-CoV-2, bacteria, fungi and parasites. Pathogens exploit CD209 family proteins to promote infection and evade the immune recognition system. CD209L and CD209 are widely expressed in SARS-CoV-2 target organs and can contribute to infection and pathogenesis. CD209 family receptors are highly susceptible to alternative splicing and genomic polymorphism, which may influence virus tropism and transmission in vivo. The carbohydrate recognition domain (CRD) and the neck/repeat region represent the key features of CD209 family proteins that are also central to facilitating cellular ligand interactions and pathogen recognition. While the neck/repeat region is involved in oligomeric dimerization, the CRD recognizes the mannose-containing structures present on specific glycoproteins such as those found on the SARS-CoV-2 spike protein. Considering the role of CD209L and related proteins in diverse pathogen recognition, this review article discusses the recent advances in the cellular and biochemical characterization of CD209 and CD209L and their roles in viral uptake, which has important implications in understanding the host-pathogen interaction, the viral pathobiology and driving vaccine development of SARS-CoV-2.
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Affiliation(s)
- Nader Rahimi
- Department of Pathology, School of Medicine, Boston University Medical Campus, Boston, MA 02118, USA
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4
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Mnich ME, van Dalen R, van Sorge NM. C-Type Lectin Receptors in Host Defense Against Bacterial Pathogens. Front Cell Infect Microbiol 2020; 10:309. [PMID: 32733813 PMCID: PMC7358460 DOI: 10.3389/fcimb.2020.00309] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/22/2020] [Indexed: 12/11/2022] Open
Abstract
Antigen-presenting cells (APCs) are present throughout the human body—in tissues, at barrier sites and in the circulation. They are critical for processing external signals to instruct both local and systemic responses toward immune tolerance or immune defense. APCs express an extensive repertoire of pattern-recognition receptors (PRRs) to detect and transduce these signals. C-type lectin receptors (CLRs) comprise a subfamily of PRRs dedicated to sensing glycans, including those expressed by commensal and pathogenic bacteria. This review summarizes recent findings on the recognition of and responses to bacteria by membrane-expressed CLRs on different APC subsets, which are discussed according to the primary site of infection. Many CLR-bacterial interactions promote bacterial clearance, whereas other interactions are exploited by bacteria to enhance their pathogenic potential. The discrimination between protective and virulence-enhancing interactions is essential to understand which interactions to target with new prophylactic or treatment strategies. CLRs are also densely concentrated at APC dendrites that sample the environment across intact barrier sites. This suggests an–as yet–underappreciated role for CLR-mediated recognition of microbiota-produced glycans in maintaining tolerance at barrier sites. In addition to providing a concise overview of identified CLR-bacteria interactions, we discuss the main challenges and potential solutions for the identification of new CLR-bacterial interactions, including those with commensal bacteria, and for in-depth structure-function studies on CLR-bacterial glycan interactions. Finally, we highlight the necessity for more relevant tissue-specific in vitro, in vivo and ex vivo models to develop therapeutic applications in this area.
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Affiliation(s)
- Malgorzata E Mnich
- Medical Microbiology, UMC Utrecht, Utrecht University, Utrecht, Netherlands.,GSK, Siena, Italy
| | - Rob van Dalen
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Nina M van Sorge
- Department of Medical Microbiology and Infection Prevention, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Netherlands Reference Laboratory for Bacterial Meningitis, Amsterdam University Medical Center, Amsterdam, Netherlands
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5
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Valverde P, Martínez JD, Cañada FJ, Ardá A, Jiménez-Barbero J. Molecular Recognition in C-Type Lectins: The Cases of DC-SIGN, Langerin, MGL, and L-Sectin. Chembiochem 2020; 21:2999-3025. [PMID: 32426893 PMCID: PMC7276794 DOI: 10.1002/cbic.202000238] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 05/19/2020] [Indexed: 12/16/2022]
Abstract
Carbohydrates play a pivotal role in intercellular communication processes. In particular, glycan antigens are key for sustaining homeostasis, helping leukocytes to distinguish damaged tissues and invading pathogens from healthy tissues. From a structural perspective, this cross‐talk is fairly complex, and multiple membrane proteins guide these recognition processes, including lectins and Toll‐like receptors. Since the beginning of this century, lectins have become potential targets for therapeutics for controlling and/or avoiding the progression of pathologies derived from an incorrect immune outcome, including infectious processes, cancer, or autoimmune diseases. Therefore, a detailed knowledge of these receptors is mandatory for the development of specific treatments. In this review, we summarize the current knowledge about four key C‐type lectins whose importance has been steadily growing in recent years, focusing in particular on how glycan recognition takes place at the molecular level, but also looking at recent progresses in the quest for therapeutics.
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Affiliation(s)
- Pablo Valverde
- CIC bioGUNE, Basque Research Technology Alliance, BRTA, Bizkaia Technology park, Building 800, 48160, Derio, Spain
| | - J Daniel Martínez
- CIC bioGUNE, Basque Research Technology Alliance, BRTA, Bizkaia Technology park, Building 800, 48160, Derio, Spain
| | - F Javier Cañada
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain.,CIBER de Enfermedades Respiratorias (CIBERES), Avda Monforte de Lemos 3-5, 28029, Madrid, Spain
| | - Ana Ardá
- CIC bioGUNE, Basque Research Technology Alliance, BRTA, Bizkaia Technology park, Building 800, 48160, Derio, Spain
| | - Jesús Jiménez-Barbero
- CIC bioGUNE, Basque Research Technology Alliance, BRTA, Bizkaia Technology park, Building 800, 48160, Derio, Spain.,Ikerbasque, Basque Foundation for Science, 48009, Bilbao, Spain.,Department of Organic Chemistry II, Faculty of Science and Technology, UPV-EHU, 48940, Leioa, Spain
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6
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Chéneau C, Coulon F, Porkolab V, Fieschi F, Laurant S, Razanajaona-Doll D, Pin JJ, Borst EM, Messerle M, Bressollette-Bodin C, Halary F. Fine Mapping the Interaction Between Dendritic Cell-Specific Intercellular Adhesion Molecule (ICAM)-3-Grabbing Nonintegrin and the Cytomegalovirus Envelope Glycoprotein B. J Infect Dis 2019; 218:490-503. [PMID: 29648611 PMCID: PMC6049025 DOI: 10.1093/infdis/jiy194] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 04/03/2018] [Indexed: 12/22/2022] Open
Abstract
Background Human cytomegalovirus (HCMV) is a leading cause of virally induced congenital disorders and morbidities in immunocompromised individuals, ie, transplant, cancer, or acquired immune deficiency syndrome patients. Human cytomegalovirus infects virtually all cell types through the envelope glycoprotein complex gH/gL/gO with or without a contribution of the pentameric gH/gL/pUL128L. Together with gH/gL, the HCMV envelope glycoprotein B (gB) contributes to the viral fusion machinery. Methods We previously showed that gB is a ligand for the C-type lectin dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) contributing to HCMV attachment to and infection of DC-SIGN-expressing cells. However, the features of the DC-SIGN/gB interaction remain unclear. To address this point, the role of glycans on gB and the consequences of mutagenesis and antibody-mediated blockades on both partners were examined in this study. Results We identified DC-SIGN amino acid residues involved in this interaction through an extensive mutagenesis study. We also showed the importance of high-mannose N-glycans decorating the asparagine residue at position 208, demonstrating that the antigenic domain 5 on gB is involved in the interaction with DC-SIGN. Finally, antibody-mediated blockades allowed us to identify DC-SIGN as a major HCMV attachment receptor on monocyte-derived dendritic cells. Conclusions Taken together, these results have permitted us to fine-map the interaction between DC-SIGN and HCMV gB.
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Affiliation(s)
- Coraline Chéneau
- Centre de Recherche en Transplantation et Immunologie UMR1064, INSERM, Université de Nantes, France.,Institut de Transplantation Urologie Néphrologie, Centre Hospitalier Universitaire (CHU) Nantes, France
| | - Flora Coulon
- Centre de Recherche en Transplantation et Immunologie UMR1064, INSERM, Université de Nantes, France.,Institut de Transplantation Urologie Néphrologie, Centre Hospitalier Universitaire (CHU) Nantes, France
| | - Vanessa Porkolab
- Université Grenoble Alpes, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Institute de Biologie Structurale, Grenoble, France
| | - Franck Fieschi
- Université Grenoble Alpes, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Institute de Biologie Structurale, Grenoble, France
| | | | | | | | - Eva Maria Borst
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Martin Messerle
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Céline Bressollette-Bodin
- Centre de Recherche en Transplantation et Immunologie UMR1064, INSERM, Université de Nantes, France.,Institut de Transplantation Urologie Néphrologie, Centre Hospitalier Universitaire (CHU) Nantes, France.,Service de Virologie Clinique, CHU Hotel Dieu, Nantes, France
| | - Franck Halary
- Centre de Recherche en Transplantation et Immunologie UMR1064, INSERM, Université de Nantes, France.,Institut de Transplantation Urologie Néphrologie, Centre Hospitalier Universitaire (CHU) Nantes, France
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7
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Jo E, Elvitigala DAS, Wan Q, Oh M, Oh C, Lee J. Identification and molecular profiling of DC-SIGN-like from big belly seahorse (Hippocampus abdominalis) inferring its potential relevancy in host immunity. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 77:270-279. [PMID: 28867209 DOI: 10.1016/j.dci.2017.08.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/30/2017] [Accepted: 08/30/2017] [Indexed: 06/07/2023]
Abstract
Dendritic-cell-specific ICAM-3-grabbing non-integrin (DC-SIGN) is a C-type lectin that functions as a pattern recognition receptor by recognizing pathogen-associated molecular patterns (PAMPs). It is also involved in various events of the dendritic cell (DC) life cycle, such as DC migration, antigen capture and presentation, and T cell priming. In this study, a DC-SIGN-like gene from the big belly seahorse Hippocampus abdominalis (designated as ShDCS-like) was identified and molecularly characterized. The putative, complete ORF was found to be 1368 bp in length, encoding a protein of 462 amino acids with a molecular mass of 52.6 kDa and a theoretical isoelectric point of 8.26. The deduced amino acid sequence contains a single carbohydrate recognition domain (CRD), in which six conserved cysteine residues and two Ca2+-binding site motifs (QPN, WND) were identified. Based on pairwise sequence analysis, ShDCS-like exhibits the highest amino acid identity (94.6%) and similarity (97.4%) with DC-SIGN-like counterpart from tiger tail seahorse Hippocampus comes. Quantitative real-time PCR revealed that ShDCS-like mRNA is transcribed universally in all tissues examined, but with abundance in kidney and gill tissues. The basal mRNA expression of ShDCS-like was modulated in blood cell, kidney, gill and liver tissues in response to the stimulation of healthy fish with lipopolysaccharides (LPS), Edwardsiella tarda, or Streptococcus iniae. Moreover, recombinant ShDCS-like-CRD domain exhibited detectable agglutination activity against different bacteria. Collectively, these results suggest that ShDCS-like may potentially involve in immune function in big belly seahorses.
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Affiliation(s)
- Eunyoung Jo
- Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea; Jeju International Marine Science Research & Education Center, Korea Institute of Ocean Science & Technology (KIOST), Jeju Special Self-Governing Province, 63349, Republic of Korea
| | - Don Anushka Sandaruwan Elvitigala
- Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea; Department of Chemistry, University of Colombo, Colombo 03, 00300, Sri Lanka
| | - Qiang Wan
- Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea
| | - Minyoung Oh
- Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea
| | - Chulhong Oh
- Jeju International Marine Science Research & Education Center, Korea Institute of Ocean Science & Technology (KIOST), Jeju Special Self-Governing Province, 63349, Republic of Korea
| | - Jehee Lee
- Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea.
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8
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Dos Santos Á, Hadjivasiliou A, Ossa F, Lim NK, Turgut A, Taylor ME, Drickamer K. Oligomerization domains in the glycan-binding receptors DC-SIGN and DC-SIGNR: Sequence variation and stability differences. Protein Sci 2016; 26:306-316. [PMID: 27859859 PMCID: PMC5275740 DOI: 10.1002/pro.3083] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 10/21/2016] [Accepted: 11/08/2016] [Indexed: 11/05/2022]
Abstract
Human dendritic cell-specific intercellular adhesion molecule-1 grabbing nonintegrin, DC-SIGN, and the sinusoidal endothelial cell receptor DC-SIGNR or L-SIGN, are closely related sugar-binding receptors. DC-SIGN acts both as a pathogen-binding endocytic receptor and as a cell adhesion molecule, while DC-SIGNR has only the pathogen-binding function. In addition to differences in the sugar-binding properties of the carbohydrate-recognition domains in the two receptors, there are sequence differences in the adjacent neck domains, which are coiled-coil tetramerization domains comprised largely of 23-amino acid repeat units. A series of model polypeptides consisting of uniform repeat units have been characterized by gel filtration, differential scanning calorimetry and circular dichroism. The results demonstrate that two features characterize repeat units which form more stable tetramers: a leucine reside in the first position of the heptad pattern of hydrophobic residues that pack on the inside of the coiled coil and an arginine residue on the surface of the coiled coil that forms a salt bridge with a glutamic acid residue in the same polypeptide chain. In DC-SIGNR from all primates, very stable repeat units predominate, so the carbohydrate-recognition domains must be held relatively closely together. In contrast, stable repeat units are found only near the membrane in DC-SIGN. The presence of residues that disrupt tetramer formation in repeat units near the carbohydrate-recognition domains of DC-SIGN would allow these domains to splay further apart. Thus, the neck domains of DC-SIGN and DC-SIGNR can contribute to the different functions of these receptors by presenting the sugar-binding sites in different contexts.
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Affiliation(s)
- Ália Dos Santos
- Department of Life Sciences, Imperial College, London, SW7 2AZ, United Kingdom
| | | | - Felipe Ossa
- Department of Life Sciences, Imperial College, London, SW7 2AZ, United Kingdom
| | - Novandy K Lim
- Department of Life Sciences, Imperial College, London, SW7 2AZ, United Kingdom
| | - Aylin Turgut
- Department of Life Sciences, Imperial College, London, SW7 2AZ, United Kingdom
| | - Maureen E Taylor
- Department of Life Sciences, Imperial College, London, SW7 2AZ, United Kingdom
| | - Kurt Drickamer
- Department of Life Sciences, Imperial College, London, SW7 2AZ, United Kingdom
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9
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Development and evaluation of a double antibody sandwich ELISA for the detection of human sDC-SIGN. J Immunol Methods 2016; 436:16-21. [PMID: 27262264 DOI: 10.1016/j.jim.2016.05.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 05/28/2016] [Accepted: 05/31/2016] [Indexed: 12/22/2022]
Abstract
sDC-SIGN is the soluble form of dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN, CD209), which is a molecule involved with pathogen recognition and immune regulation. However, there is no commercially available ELISA kit for detecting human sDC-SIGN, and the normal range of this molecule is unknown. Here, we describe an ELISA for detecting human sDC-SIGN with high specificity. First, sDC-SIGN protein was expressed and purified. Monoclonal and polyclonal antibodies were then raised against the purified protein and subsequently characterized. A sandwich ELISA was developed using polyclonal antibodies specific for sDC-SIGN for capture and a biotin-labeled monoclonal antibody specific for sDC-SIGN for detection of protein. This method has sensitivity up to 0.2 ng/ml. Using this ELISA, we found that the concentration of sDC-SIGN in sera of healthy volunteers ranges from 0-319 ng/ml with a mean concentration of 27.14 ng/ml. Interestingly, the concentration of sDC-SIGN in sera from patients with cancer or chronic hepatitis B virus (CHB) infection was lower than that of health controls. The mean concentrations of sDC-SIGN in cancer patients and chronic hepatitis B virus infection patients were 3.2 ng/ml and 3.8 ng/ml, respectively. We developed a sandwich ELISA for detecting human sDC-SIGN and demonstrated its use by assessing sera concentrations of sDC-SIGN in patients with cancer and chronic CHB infection compared to that of healthy controls.
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10
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Garcia-Parajo MF, Cambi A, Torreno-Pina JA, Thompson N, Jacobson K. Nanoclustering as a dominant feature of plasma membrane organization. J Cell Sci 2015; 127:4995-5005. [PMID: 25453114 DOI: 10.1242/jcs.146340] [Citation(s) in RCA: 188] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Early studies have revealed that some mammalian plasma membrane proteins exist in small nanoclusters. The advent of super-resolution microscopy has corroborated and extended this picture, and led to the suggestion that many, if not most, membrane proteins are clustered at the plasma membrane at nanoscale lengths. In this Commentary, we present selected examples of glycosylphosphatidyl-anchored proteins, Ras family members and several immune receptors that provide evidence for nanoclustering. We advocate the view that nanoclustering is an important part of the hierarchical organization of proteins in the plasma membrane. According to this emerging picture, nanoclusters can be organized on the mesoscale to form microdomains that are capable of supporting cell adhesion, pathogen binding and immune cell-cell recognition amongst other functions. Yet, a number of outstanding issues concerning nanoclusters remain open, including the details of their molecular composition, biogenesis, size, stability, function and regulation. Notions about these details are put forth and suggestions are made about nanocluster function and why this general feature of protein nanoclustering appears to be so prevalent.
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Affiliation(s)
- Maria F Garcia-Parajo
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
| | - Alessandra Cambi
- Nanobiophysics, MIRA Institute for Biomedical Technology and Technical Medicine and MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, The Netherlands Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands
| | - Juan A Torreno-Pina
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - Nancy Thompson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA
| | - Ken Jacobson
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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11
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Pederson K, Mitchell DA, Prestegard JH. Structural characterization of the DC-SIGN-Lewis(X) complex. Biochemistry 2014; 53:5700-9. [PMID: 25121780 PMCID: PMC4159204 DOI: 10.1021/bi5005014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dendritic cell-specific intracellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) is a C-type lectin highly expressed on the surface of antigen-presenting dendritic cells. DC-SIGN mediates interactions among dendritic cells, pathogens, and a variety of epithelia, myeloid cells, and endothelia by binding to high mannose residues on pathogenic invaders or fucosylated residues on the membranes of other immune cells. Although these interactions are normally beneficial, they can also contribute to disease. The structural characterization of binding geometries is therefore of interest as a basis for the construction of mimetics that can mediate the effects of abnormal immune response. Here, we report the structural characteristics of the interaction of the DC-SIGN carbohydrate recognition domain (CRD) with a common fucosylated entity, the Lewis(X) trisaccharide (Le(X)), using NMR methods. Titration of the monomeric DC-SIGN CRD with Le(X) monitored by 2D NMR revealed significant perturbations of DC-SIGN cross-peak positions in (1)H-(15)N heteronuclear single quantum coherence (HSQC) spectra and identified residues near the binding site. Additionally, saturation transfer difference (STD) and transferred nuclear Overhauser effect (trNOE) NMR experiments, using a tetrameric form of DC-SIGN, identified binding epitopes and bound conformations of the Le(X) ligand. The restraints derived from these multiple experiments were used to generate models for the binding of Le(X) to the DC-SIGN CRD. Ranking of the models based on the fit of model-based simulations of the trNOE data and STD buildup curves suggested conformations distinct from those seen in previous crystal structures. The new conformations offer insight into how differences between binding of Lewis(X) and mannose-terminated saccharides may be propagated.
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Affiliation(s)
- Kari Pederson
- Complex Carbohydrate Research Center, University of Georgia , Athens, Georgia 30602, United States
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12
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Liu P, Wang X, Itano MS, Neumann AK, de Silva AM, Jacobson K, Thompson NL. Low copy numbers of DC-SIGN in cell membrane microdomains: implications for structure and function. Traffic 2013; 15:179-96. [PMID: 24313910 DOI: 10.1111/tra.12138] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 11/07/2013] [Accepted: 11/11/2013] [Indexed: 12/17/2022]
Abstract
Presently, there are few estimates of the number of molecules occupying membrane domains. Using a total internal reflection fluorescence microscopy (TIRFM) imaging approach, based on comparing the intensities of fluorescently labeled microdomains with those of single fluorophores, we measured the occupancy of DC-SIGN, a C-type lectin, in membrane microdomains. DC-SIGN or its mutants were labeled with primary monoclonal antibodies (mAbs) in either dendritic cells (DCs) or NIH3T3 cells, or expressed as GFP fusions in NIH3T3 cells. The number of DC-SIGN molecules per microdomain ranges from only a few to over 20, while microdomain dimensions range from the diffraction limit to > 1 µm. The largest fraction of microdomains, appearing at the diffraction limit, in either immature DCs or 3 T3 cells contains only 4-8 molecules of DC-SIGN, consistent with our preliminary super-resolution Blink microscopy estimates. We further show that these small assemblies are sufficient to bind and efficiently internalize a small (∼ 50 nm) pathogen, dengue virus, leading to infection of host cells.
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Affiliation(s)
- Ping Liu
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7090, USA
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13
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Abstract
The C-type lectins DC-SIGN, DC-SIGNR and LSECtin are encoded by the lectin gene cluster on chromosome 19p13.3 and perform cell-adhesion and pathogen recognition functions on dendritic cells, liver cells and lymph node sinusoidal endothelial cells. DC-SIGN and DC-SIGNR share similar overall gene and protein molecule structures, and they exhibit high affinity for high-mannose carbohydrates. LSECtin, a Ca2+-dependent C-type lectin, interacts with mannose, NAcGlc and fucose. These lectins allow pathogen recognition (e.g., viruses, bacteria and allergens) and cell adhesion for dendritic and endothelial cells in different tissues, which may enhance the infection and facilitate the spread of those pathogens. A better understanding of these lectins may yield information about how pathogens are captured by particular cells and how they spread in different tissues. These studies would provide more detail about the physiopathological mechanisms of viral and bacterial infections and may also lead to new strategies to treat or prevent infections.
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Affiliation(s)
- Feng Zhang
- 1Department of Clinical Biochemistry, College of Laboratory Diagnostic Medicine, Dalian Medical University, Dalian, China
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14
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Probert F, Whittaker SBM, Crispin M, Mitchell DA, Dixon AM. Solution NMR analyses of the C-type carbohydrate recognition domain of DC-SIGNR protein reveal different binding modes for HIV-derived oligosaccharides and smaller glycan fragments. J Biol Chem 2013; 288:22745-57. [PMID: 23788638 PMCID: PMC3829359 DOI: 10.1074/jbc.m113.458299] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 06/13/2013] [Indexed: 01/08/2023] Open
Abstract
The C-type lectin DC-SIGNR (dendritic cell-specific ICAM-3-grabbing non-integrin-related; also known as L-SIGN or CD299) is a promising drug target due to its ability to promote infection and/or within-host survival of several dangerous pathogens (e.g. HIV and severe acute respiratory syndrome coronavirus (SARS)) via interactions with their surface glycans. Crystallography has provided excellent insight into the mechanism by which DC-SIGNR interacts with small glycans, such as (GlcNAc)2Man3; however, direct observation of complexes with larger, physiological oligosaccharides, such as Man9GlcNAc2, remains elusive. We have utilized solution-state nuclear magnetic resonance spectroscopy to investigate DC-SIGNR binding and herein report the first backbone assignment of its active, calcium-bound carbohydrate recognition domain. Direct interactions with the small sugar fragments Man3, Man5, and (GlcNAc)2Man3 were investigated alongside Man9GlcNAc derived from recombinant gp120 (present on the HIV viral envelope), providing the first structural data for DC-SIGNR in complex with a virus-associated ligand, and unique binding modes were observed for each glycan. In particular, our data show that DC-SIGNR has a different binding mode for glycans on the HIV viral envelope compared with the smaller glycans previously observed in the crystalline state. This suggests that using the binding mode of Man9GlcNAc, instead of those of small glycans, may provide a platform for the design of DC-SIGNR inhibitors selective for high mannose glycans (like those on HIV). (15)N relaxation measurements provided the first information on the dynamics of the carbohydrate recognition domain, demonstrating that it is a highly flexible domain that undergoes ligand-induced conformational and dynamic changes that may explain the ability of DC-SIGNR to accommodate a range of glycans on viral surfaces.
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Affiliation(s)
- Fay Probert
- From the Molecular Organisation and Assembly in Cells Doctoral Training Centre
| | - Sara B.-M. Whittaker
- the Henry Wellcome Building for Biomolecular NMR Spectroscopy, Birmingham Cancer Research UK Centre, School of Cancer Sciences, University of Birmingham, Vincent Drive, Edgbaston, Birmingham B15 2TT, United Kingdom, and
| | - Max Crispin
- the Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | | | - Ann M. Dixon
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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15
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Garcia-Vallejo JJ, van Kooyk Y. The physiological role of DC-SIGN: a tale of mice and men. Trends Immunol 2013; 34:482-6. [PMID: 23608151 DOI: 10.1016/j.it.2013.03.001] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/08/2013] [Accepted: 03/10/2013] [Indexed: 02/01/2023]
Abstract
The innate immune receptor DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3 grabbing non-integrin) was discovered over a decade ago and was initially identified as a pattern recognition receptor. In addition to its ability to recognize a broad range of pathogen-derived ligands and self-glycoproteins, DC-SIGN also mediates intercellular adhesion, as well as antigen uptake and signaling, which is a functional hallmark of dendritic cells (DCs). Most research on DC-SIGN has relied on in vitro studies. The in vivo function of DC-SIGN is difficult to address, in part because there are eight genetic homologs in mice with no clear DC-SIGN ortholog. Here, we summarize the functions attributed to DC-SIGN based on in vitro data and discuss the limitations of available mouse models to uncover the physiological role of this receptor in vivo.
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Affiliation(s)
- Juan J Garcia-Vallejo
- Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, 1081BT, The Netherlands
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16
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Jégouzo SAF, Quintero-Martínez A, Ouyang X, dos Santos Á, Taylor ME, Drickamer K. Organization of the extracellular portion of the macrophage galactose receptor: a trimeric cluster of simple binding sites for N-acetylgalactosamine. Glycobiology 2013; 23:853-64. [PMID: 23507965 PMCID: PMC3671775 DOI: 10.1093/glycob/cwt022] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The properties of the human macrophage galactose receptor have been investigated. Specificity for N-acetylgalactosamine (GalNAc) residues with exposed 3- and 4-hydroxyl groups explains virtually all of the results obtained from a recently expanded array of synthetic glycans and is consistent with a model for the structure of the binding site. This simple interaction is sufficient to explain the ability of the receptor to bind to tumor-cell glycans bearing Tn and sialyl-Tn antigens, but not to more elaborate O-linked glycans that predominate on normal cells. This specificity also allows for binding of parasite glycans and screening of an array of bacterial outer membrane oligosaccharides confirms that the receptor binds to a subset of these structures with appropriately exposed GalNAc residues. A key feature of the receptor is the clustering of binding sites in the extracellular portion of the protein, which retains the trimeric structure observed in the cell membrane. Chemical crosslinking, gel filtration, circular dichroism analysis and differential scanning calorimetry demonstrate that this trimeric structure of the receptor is stabilized by an α-helical coiled coil that extends from the surface of the membrane to the globular carbohydrate-recognition domains. The helical neck domains form independent trimerization domains. Taken together, these results indicate that the macrophage galactose receptor shares many of the features of serum mannose-binding protein, in which clusters of monosaccharide-binding sites serve as detectors for a simple epitope that is not common on endogenous cell surface glycans but that is abundant on the surfaces of tumor cells and certain pathogens.
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Affiliation(s)
- Sabine A F Jégouzo
- Department of Life Sciences, Imperial College, Sir Ernst Chain Building, London SW7 2AZ, UK
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17
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Manzo C, Torreno-Pina JA, Joosten B, Reinieren-Beeren I, Gualda EJ, Loza-Alvarez P, Figdor CG, Garcia-Parajo MF, Cambi A. The neck region of the C-type lectin DC-SIGN regulates its surface spatiotemporal organization and virus-binding capacity on antigen-presenting cells. J Biol Chem 2012; 287:38946-55. [PMID: 23019323 DOI: 10.1074/jbc.m112.380121] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The C-type lectin DC-SIGN expressed on dendritic cells (DCs) facilitates capture and internalization of a plethora of different pathogens. Although it is known that DC-SIGN organizes in nanoclusters at the surface of DCs, the molecular mechanisms responsible for this well defined nanopatterning and role in viral binding remain enigmatic. By combining biochemical and advanced biophysical techniques, including optical superresolution and single particle tracking, we demonstrate that DC-SIGN intrinsic nanoclustering strictly depends on its molecular structure. DC-SIGN nanoclusters exhibited free, Brownian diffusion on the cell membrane. Truncation of the extracellular neck region, known to abrogate tetramerization, significantly reduced nanoclustering and concomitantly increased lateral diffusion. Importantly, DC-SIGN nanocluster dissolution exclusively compromised binding to nanoscale size pathogens. Monte Carlo simulations revealed that heterogeneity on nanocluster density and spatial distribution confers broader binding capabilities to DC-SIGN. As such, our results underscore a direct relationship between spatial nanopatterning, driven by intermolecular interactions between the neck regions, and receptor diffusion to provide DC-SIGN with the exquisite ability to dock pathogens at the virus length scale. Insight into how virus receptors are organized prior to virus binding and how they assemble into functional platforms for virus docking is helpful to develop novel strategies to prevent virus entry and infection.
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Affiliation(s)
- Carlo Manzo
- Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
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18
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Itano MS, Steinhauer C, Schmied JJ, Forthmann C, Liu P, Neumann AK, Thompson NL, Tinnefeld P, Jacobson K. Super-resolution imaging of C-type lectin and influenza hemagglutinin nanodomains on plasma membranes using blink microscopy. Biophys J 2012; 102:1534-42. [PMID: 22500753 DOI: 10.1016/j.bpj.2012.02.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 01/30/2012] [Accepted: 02/13/2012] [Indexed: 11/28/2022] Open
Abstract
Dendritic cells express DC-SIGN, a C-type lectin (CTL) that binds a variety of pathogens and facilitates their uptake for subsequent antigen presentation. DC-SIGN forms remarkably stable microdomains on the plasma membrane. However, inner leaflet lipid markers are able to diffuse through these microdomains suggesting that, rather than being densely packed with DC-SIGN proteins, an elemental substructure exists. Therefore, a super-resolution imaging technique, Blink Microscopy (Blink), was applied to further investigate the lateral distribution of DC-SIGN. Blink indicates that DC-SIGN, another CTL (CD206), and influenza hemagglutinin (HA) are all localized in small (∼80 nm in diameter) nanodomains. DC-SIGN and CD206 nanodomains are randomly distributed on the plasma membrane, whereas HA nanodomains cluster on length scales up to several microns. We estimate, as a lower limit, that DC-SIGN and HA nanodomains contain on average two tetramers or two trimers, respectively, whereas CD206 is often nonoligomerized. Two-color Blink determined that different CTLs rarely occupy the same nanodomain, although they appear colocalized using wide-field microscopy. What to our knowledge is a novel domain structure emerges in which elemental nanodomains, potentially capable of binding viruses, are organized in a random fashion; evidently, these nanodomains can be clustered into larger microdomains that act as receptor platforms for larger pathogens like yeasts.
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Affiliation(s)
- Michelle S Itano
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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19
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Liu P, Wang X, Itano MS, Neumann AK, Jacobson K, Thompson NL. The formation and stability of DC-SIGN microdomains require its extracellular moiety. Traffic 2012; 13:715-26. [PMID: 22292921 DOI: 10.1111/j.1600-0854.2012.01337.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/29/2012] [Accepted: 01/31/2012] [Indexed: 12/25/2022]
Abstract
Dendritic cell-specific intercellular adhesion molecule (ICAM)-3-grabbing non-integrin (DC-SIGN) is a Ca(2+) -dependent transmembrane lectin that binds a large variety of pathogens and facilitates their uptake for subsequent antigen presentation. This receptor is present in cell surface microdomains, but factors involved in microdomain formation and their exceptional stability are not clear. To determine which domain/motif of DC-SIGN facilitates its presence in microdomains, we studied mutations at key locations including truncation of the cytoplasmic tail, and ectodomain mutations that resulted in the removal of the N-linked glycosylation site, the tandem repeats and the carbohydrate recognition domain (CRD), as well as modification of the calcium sites in the CRD required for carbohydrate binding. Confocal imaging and fluorescence recovery after photobleaching measurements showed that the cytoplasmic domain and the N-linked glycosylation site do not affect the ability of DC-SIGN to form stable microdomains. However, truncation of the CRD results in complete loss of visible microdomains and subsequent lateral diffusion of the mutants. Apart from cell adhesions, membrane domains are thought to be localized primarily via the cytoskeleton. By contrast, we propose that interactions between the CRD of DC-SIGN and the extracellular matrix and/or cis interactions with transmembrane scaffolding protein(s) play an essential role in organizing these microdomains.
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Affiliation(s)
- Ping Liu
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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20
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Abstract
In the immune system, C-type lectins and CTLDs have been shown to act both as adhesion and as pathogen recognition receptors. The Dendritic cell-specific ICAM-3 grabbing non-integrin (DC-SIGN) and its homologs in human and mouse represent an important C-type lectin family. DC-SIGN contains a lectin domain that recognizes in a Ca2+-dependent manner carbohydrates such as mannose-containing structures present on glycoproteins such as ICAM-2 and ICAM-3. DC-SIGN is a prototype C-type lectin organized in microdomains, which have their role as pathogen recognition receptors in sensing microbes. Although the integrin LFA-1 is a counter-receptor for both ICAM-2 and ICAM-3 on DC, DC-SIGN is the high affinity adhesion receptor for ICAM-2/-3. While cell–cell contact is a primary function of selectins, collectins are specialized in recognition of pathogens. Interestingly, DC-SIGN is a cell adhesion receptor as well as a pathogen recognition receptor. As adhesion receptor, DC-SIGN mediates the contact between dendritic cells (DCs) and T lymphocytes, by binding to ICAM-3, and mediates rolling of DCs on endothelium, by interacting with ICAM-2. As pathogen receptor, DC-SIGN recognizes a variety of microorganisms, including viruses, bacteria, fungi and several parasites (Cambi et al. 2005). The natural ligands of DC-SIGN consist of mannose oligosaccharides or fucose-containing Lewis-type determinants. In this chapter, we shall focus on the structure and functions of DC-SIGN and related CTLDs in the recognition of pathogens, the molecular and structural determinants that regulate the interaction with pathogen-associated molecular patterns. The heterogeneity of carbohydrate residues exposed on cellular proteins and pathogens regulates specific binding of DC-expressed C-type lectins that contribute to the diversity of immune responses created by DCs (van Kooyk et al. 2003a; Cambi et al. 2005).
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21
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Itano MS, Neumann AK, Liu P, Zhang F, Gratton E, Parak WJ, Thompson NL, Jacobson K. DC-SIGN and influenza hemagglutinin dynamics in plasma membrane microdomains are markedly different. Biophys J 2011; 100:2662-70. [PMID: 21641311 DOI: 10.1016/j.bpj.2011.04.044] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 04/11/2011] [Accepted: 04/14/2011] [Indexed: 11/24/2022] Open
Abstract
DC-SIGN, a Ca(2+)-dependent transmembrane lectin, is found assembled in microdomains on the plasma membranes of dendritic cells. These microdomains bind a large variety of pathogens and facilitate their uptake for subsequent antigen presentation. In this study, DC-SIGN dynamics in microdomains were explored with several fluorescence microscopy methods and compared with dynamics for influenza hemagglutinin (HA), which is also found in plasma membrane microdomains. Fluorescence imaging indicated that DC-SIGN microdomains may contain other C-type lectins and that the DC-SIGN cytoplasmic region is not required for microdomain formation. Fluorescence recovery after photobleaching measurements showed that neither full-length nor cytoplasmically truncated DC-SIGN in microdomains appreciably exchanged with like molecules in other microdomains and the membrane surround, whereas HA in microdomains exchanged almost completely. Line-scan fluorescence correlation spectroscopy indicated an essentially undetectable lateral mobility for DC-SIGN but an appreciable mobility for HA within their respective domains. Single-particle tracking with defined-valency quantum dots confirmed that HA has significant mobility within microdomains, whereas DC-SIGN does not. By contrast, fluorescence recovery after photobleaching indicated that inner leaflet lipids are able to move through DC-SIGN microdomains. The surprising stability of DC-SIGN microdomains may reflect structural features that enhance pathogen uptake either by providing high-avidity platforms and/or by protecting against rapid microdomain endocytosis.
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Affiliation(s)
- Michelle S Itano
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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22
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Leckband DE, Menon S, Rosenberg K, Graham SA, Taylor ME, Drickamer K. Geometry and adhesion of extracellular domains of DC-SIGNR neck length variants analyzed by force-distance measurements. Biochemistry 2011; 50:6125-32. [PMID: 21650186 PMCID: PMC3140775 DOI: 10.1021/bi2003444] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
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Force–distance measurements have been used to examine differences in the interaction of the dendritic cell glycan-binding receptor DC-SIGN and the closely related endothelial cell receptor DC-SIGNR (L-SIGN) with membranes bearing glycan ligands. The results demonstrate that upon binding to membrane-anchored ligand, DC-SIGNR undergoes a conformational change similar to that previously observed for DC-SIGN. The results also validate a model for the extracellular domain of DC-SIGNR derived from crystallographic studies. Force measurements were performed with DC-SIGNR variants that differ in the length of the neck that result from genetic polymorphisms, which encode different numbers of the 23-amino acid repeat sequences that constitute the neck. The findings are consistent with an elongated, relatively rigid structure of the neck repeat observed in crystals. In addition, differences in the lengths of DC-SIGN and DC-SIGNR extracellular domains with equivalent numbers of neck repeats support a model in which the different dispositions of the carbohydrate-recognition domains in DC-SIGN and DC-SIGNR result from variations in the sequences of the necks.
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Affiliation(s)
- Deborah E Leckband
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
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23
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Raska M, Novak J. Involvement of Envelope-Glycoprotein Glycans in HIV-1 Biology and Infection. Arch Immunol Ther Exp (Warsz) 2010; 58:191-208. [DOI: 10.1007/s00005-010-0072-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 11/30/2009] [Indexed: 01/24/2023]
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24
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Segmented helical structure of the neck region of the glycan-binding receptor DC-SIGNR. J Mol Biol 2009; 394:613-20. [PMID: 19835887 PMCID: PMC2971551 DOI: 10.1016/j.jmb.2009.10.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 09/30/2009] [Accepted: 10/01/2009] [Indexed: 11/25/2022]
Abstract
Carbohydrate-recognition domains (CRDs) in the glycan-binding receptors DC-SIGN (dendritic-cell-specific intercellular adhesion molecule 1-grabbing nonintegrin; CD209) and DC-SIGNR (DC-SIGN-related receptor, also known as L-SIGN and variously designated CD209L and CD299) are projected from the membrane surface by extended neck domains containing multiple repeats of a largely conserved 23-amino-acid sequence motif. Crystals of a fragment of the neck domain of DC-SIGNR containing multiple repeats in which each molecule extends through multiple unit cells, such that the observed crystallographic asymmetric unit represents one repeat averaged over six repeats of the protein, have been obtained. The repeats are largely α-helical. Based on the structure and arrangement of the repeats in the crystal, the neck region can be described as a series of four-helix bundles connected by short, non-helical linkers. Combining the structure of the isolated neck domain with a previously determined overlapping structure of the distal end of the neck region with the CRDs attached provides a model of the almost-complete extracellular portion of the receptor. The results are consistent with previous characterization of the extended structure for the isolated neck region and the extracellular domain. The organization of the neck suggests how CRDs may be disposed differently in DC-SIGN compared with DC-SIGNR and in variant forms of DC-SIGNR assembled from polypeptides with different numbers of repeats in the neck domain.
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25
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Capture and transmission of HIV-1 by the C-type lectin L-SIGN (DC-SIGNR) is inhibited by carbohydrate-binding agents and polyanions. Antiviral Res 2009; 83:61-70. [PMID: 19514109 DOI: 10.1016/j.antiviral.2009.03.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
It was recently shown that capture of HIV-1 by DC-SIGN-expressing cells and the subsequent transmission of HIV to CD4+ T-lymphocytes can be prevented by carbohydrate-binding agents (CBAs), whereas polyanions were unable to block virus capture by DC-SIGN. In this study, we could show that a short pre-exposure of HIV-1 to both mannose- and N-acetylglucosamine (GlcNAc)-specific CBAs or polyanions dose-dependently prevented virus capture by L-SIGN-expressing 293T-REx/L-SIGN cells and subsequent syncytia formation in co-cultures of the drug-exposed HIV-1-captured 293T-REx/L-SIGN cells and uninfected C8166 CD4+ T-lymphocytes. Additionally, the inhibitory potential of the compounds against L-SIGN-mediated HIV-1 capture and transmission was more pronounced than observed for DC-SIGN expressing293T-REx/DC-SIGN cells. The excess value of CBAs and polyanions to prevent HIV-1 capture and transmission by DC-SIGN and L-SIGN-expressing cells to susceptible T-lymphocytes could be of interest for the development of new drug leads targeting HIV entry/fusion.
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