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Hoffmann A, Kerr S, Jellusova J, Zhang J, Weisel F, Wellmann U, Winkler TH, Kneitz B, Crocker PR, Nitschke L. Siglec-G is a B1 cell–inhibitory receptor that controls expansion and calcium signaling of the B1 cell population. Nat Immunol 2007; 8:695-704. [PMID: 17572677 DOI: 10.1038/ni1480] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Accepted: 05/14/2007] [Indexed: 01/24/2023]
Abstract
B1 cells are an important cell population for the production of natural antibodies and for antibacterial immunoglobulin responses. Here we identified the mouse protein Siglec-G as a B1 cell inhibitory receptor. Siglec-G was expressed in a B cell-restricted way, with large amounts present in B1 cells. When overexpressed, Siglec-G inhibited B cell receptor-mediated calcium signaling. Siglec-G-deficient mice had massive expansion of the B1a cell population, which began early in development and was B cell intrinsic. Siglec-G-deficient mice had higher titers of natural IgM antibodies but not a higher penetrance of IgG autoantibodies. Siglec-G-deficient B1 cells showed a strongly enhanced calcium signaling. Our results demonstrate that Siglec-G-dependent negative regulation exists in B1 cells, which may explain the naturally muted signaling response of B1 cells.
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Affiliation(s)
- Anja Hoffmann
- Department of Genetics, University of Erlangen, 91058 Erlangen, Germany
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52
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Tateno H, Li H, Schur MJ, Bovin N, Crocker PR, Wakarchuk WW, Paulson JC. Distinct endocytic mechanisms of CD22 (Siglec-2) and Siglec-F reflect roles in cell signaling and innate immunity. Mol Cell Biol 2007; 27:5699-710. [PMID: 17562860 PMCID: PMC1952126 DOI: 10.1128/mcb.00383-07] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Sialic acid-binding immunoglobulin-like lectins (siglecs) are predominately expressed on immune cells. They are best known as regulators of cell signaling mediated by cytoplasmic tyrosine motifs and are increasingly recognized as receptors for pathogens that bear sialic acid-containing glycans. Most siglec proteins undergo endocytosis, an activity tied to their roles in cell signaling and innate immunity. Here, we investigate the endocytic pathways of two siglec proteins, CD22 (Siglec-2), a regulator of B-cell signaling, and mouse eosinophil Siglec-F, a member of the rapidly evolving CD33-related siglec subfamily that are expressed on cells of the innate immune system. CD22 exhibits hallmarks of clathrin-mediated endocytosis and traffics to recycling compartments, consistent with previous reports demonstrating its localization to clathrin domains. Like CD22, Siglec-F mediates endocytosis of anti-Siglec-F and sialoside ligands, a function requiring intact tyrosine-based motifs. In contrast, however, we find that Siglec-F endocytosis is clathrin and dynamin independent, requires ADP ribosylation factor 6, and traffics to lysosomes. The results suggest that these two siglec proteins have evolved distinct endocytic mechanisms consistent with roles in cell signaling and innate immunity.
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Affiliation(s)
- Hiroaki Tateno
- Department of Molecular Biology and Molecular and Experimental Medicine, The Scripps Research Institute, San Diego, CA, USA
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53
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Zhang M, Angata T, Cho JY, Miller M, Broide DH, Varki A. Defining the in vivo function of Siglec-F, a CD33-related Siglec expressed on mouse eosinophils. Blood 2007; 109:4280-7. [PMID: 17272508 PMCID: PMC1885492 DOI: 10.1182/blood-2006-08-039255] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD33-related Siglecs (CD33rSiglecs) are a family of sialic acid-recognizing lectins on immune cells whose biologic functions are unknown. We studied in vivo functions of Siglec-F, the CD33rSiglec expressed on mouse eosinophils, which are prominent in allergic processes. Induction of allergic lung inflammation in mice caused up-regulation of Siglec-F on blood and bone marrow eosinophils, accompanied by newly induced expression on some CD4(+) cells, as well as quantitative up-regulation of endogenous Siglec-F ligands in the lung tissue and airways. Taken together with the tyrosine-based inhibitory motif in the cytosolic tail of Siglec-F, the data suggested a negative feedback loop, controlling allergic responses of eosinophils and helper T cells, via Siglec-F and Siglec-F ligands. To pursue this hypothesis, we created Siglec-F-null mice. Allergen-challenged null mice showed increased lung eosinophil infiltration, enhanced bone marrow and blood eosinophilia, delayed resolution of lung eosinophilia, and reduced peribronchial-cell apoptosis. Anti-Siglec-F antibody cross-linking also enhanced eosinophil apoptosis in vitro. These data support the proposed negative feedback role for Siglec-F, represent the first in vivo demonstration of biologic functions for any CD33rSiglec, and predict a role for human Siglec-8 (the isofunctional paralog of mouse Siglec-F) in regulating the pathogenesis of human eosinophil-mediated disorders.
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MESH Headings
- Animals
- Antigens, CD/chemistry
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/immunology
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Apoptosis/drug effects
- Bronchial Provocation Tests
- Disease Models, Animal
- Eosinophils/metabolism
- Gene Expression Regulation
- Hypersensitivity/genetics
- Hypersensitivity/metabolism
- Lung Diseases/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- N-Acetylneuraminic Acid/pharmacology
- Respiratory Mucosa/drug effects
- Respiratory Mucosa/metabolism
- Sequence Homology
- Sialic Acid Binding Ig-like Lectin 3
- Sialic Acid Binding Immunoglobulin-like Lectins
- T-Lymphocytes/metabolism
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Affiliation(s)
- Mai Zhang
- Glycobiology Research and Training Center, Departments of Medicine and Cellular & Molecular Medicine, and Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093-0687, USA
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54
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Angata T, Hayakawa T, Yamanaka M, Varki A, Nakamura M. Discovery of Siglec-14, a novel sialic acid receptor undergoing concerted evolution with Siglec-5 in primates. FASEB J 2006; 20:1964-73. [PMID: 17012248 DOI: 10.1096/fj.06-5800com] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Immune receptors that show high mutual sequence similarity and have antagonizing signaling properties are called paired receptors, and are believed to fine-tune immune responses. Siglecs are sialic acid-recognizing receptors of the immunoglobulin (Ig) superfamily expressed on immune cells. Human Siglec-5, encoded by SIGLEC5 gene, has four extracellular Ig-like domains and a cytosolic inhibitory motif. We discovered human Siglec-14 with three Ig-like domains, encoded by the SIGLEC14 gene, adjacent to SIGLEC5. Human Siglec-14 has almost complete sequence identity with human Siglec-5 at the first two Ig-like domains, shows a glycan binding preference similar to that of human Siglec-5, and associates with the activating adapter protein DAP12. Thus, Siglec-14 and Siglec-5 appear to be the first glycan binding paired receptors. Near-complete sequence identity of the amino-terminal part of human Siglec-14 and Siglec-5 indicates partial gene conversion between SIGLEC14 and SIGLEC5. Remarkably, SIGLEC14 and SIGLEC5 in other primates also show evidence of gene conversions within each lineage. Evidently, balancing the interactions between Siglec-14, Siglec-5 and their common ligand(s) had selective advantage during the course of evolution. The "essential arginine" critical for sialic acid recognition in both Siglec-14 and Siglec-5 is present in humans but mutated in almost all great ape alleles.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/metabolism
- Arginine/genetics
- Evolution, Molecular
- Gene Conversion
- Humans
- Lectins/genetics
- Lectins/metabolism
- Membrane Proteins
- Polysaccharides/metabolism
- Primates
- Protein Binding
- Protein Structure, Tertiary
- Receptors, Cell Surface/genetics
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
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Affiliation(s)
- Takashi Angata
- Research Center for Glycoscience, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
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55
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Abstract
Sialic acids are a family of acidic sugars with a 9-carbon backbone, prominently expressed in animals of deuterostome lineage. Siglecs are the largest family of vertebrate endogenous receptors that recognize glycoconjugates containing sialic acids. Although a few Siglecs are well-conserved throughout vertebrate evolution and show similar binding preference regardless of the species of origin, most others, particularly the CD33-related subfamily of Siglecs, show marked inter-species differences in repertoire, sequence, and binding preference. The diversification of CD33-related Siglecs may be driven by direct competition against pathogens, and/or by necessity to catch up with the changing landscape of endogenous glycans, which may in turn be changing to escape exploitation by other pathogens.
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Affiliation(s)
- Takashi Angata
- Research Center for Glycoscience, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki, Japan.
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56
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Yamada Y, Rothenberg ME, Lee AW, Akei HS, Brandt EB, Williams DA, Cancelas JA. The FIP1L1-PDGFRA fusion gene cooperates with IL-5 to induce murine hypereosinophilic syndrome (HES)/chronic eosinophilic leukemia (CEL)-like disease. Blood 2006; 107:4071-9. [PMID: 16418325 PMCID: PMC1895281 DOI: 10.1182/blood-2005-08-3153] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dysregulated tyrosine kinase activity by the Fip1-like1 (FIP1L1)-platelet-derived growth factor receptor alpha (PDGFRA) (F/P) fusion gene has been identified as a cause of clonal hypereosinophilic syndrome (HES), called F/P-positive chronic eosinophilic leukemia (CEL) in humans. However, transplantation of F/P-transduced hematopoietic stem cells/progenitors (F/P(+) HSCs/Ps) into mice results in a chronic myelogenous leukemia-like disease, which does not resemble HES. Because a subgroup of patients with HES show T-cell-dependent interleukin-5 (IL-5) overexpression, we determined if expression of the F/P fusion gene in the presence of transgenic T-cell IL-5 overexpression in mice induces HES-like disease. Mice that received a transplant of CD2-IL-5-transgenic F/P(+) HSC/Ps (IL-5Tg-F/P) developed intense leukocytosis, strikingly high eosinophilia, and eosinophilic infiltration of nonhematopoietic as well as hematopoietic tissues, a phenotype resembling human HES. The disease phenotype was transferable to secondary transplant recipients of a high cell dose, suggesting involvement of a short-term repopulating stem cell or an early myeloid progenitor. Induction of significant eosinophilia was specific for F/P since expression of another fusion oncogene, p210-BCR/ABL, in the presence of IL-5 overexpression was characterized by a significantly lower eosinophilia than IL-5Tg-F/P recipients. These results suggest that F/P is not sufficient to induce a HES/CEL-like disease but requires a second event associated with IL-5 overexpression.
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Affiliation(s)
- Yoshiyuki Yamada
- Division of Allergy and Immunology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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57
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Zhang J, Raper A, Sugita N, Hingorani R, Salio M, Palmowski MJ, Cerundolo V, Crocker PR. Characterization of Siglec-H as a novel endocytic receptor expressed on murine plasmacytoid dendritic cell precursors. Blood 2006; 107:3600-8. [PMID: 16397130 DOI: 10.1182/blood-2005-09-3842] [Citation(s) in RCA: 187] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We describe the cloning and characterization of Siglec-H, a novel murine CD33-related siglec-like molecule with 2 immunoglobulin domains. Unlike other CD33-related siglecs, Siglec-H lacks tyrosine-based signaling motifs in its cytoplasmic tail. Although Siglec-H has the typical structural features required for sialic acid binding, no evidence for carbohydrate recognition was obtained. Specific monoclonal and polyclonal antibodies (Abs) were raised to Siglec-H and used to define its cellular expression pattern and functional properties. By flow cytometry, Siglec-H was expressed specifically on plasmacytoid dendritic cell (pDC) precursors in bone marrow, spleen, blood, and lymph nodes. Staining of tissue sections showed that Siglec-H was also expressed in a subset of marginal zone macrophages in the spleen and in medullary macrophages in lymph nodes. Using bone marrow-derived pDC precursors that express Siglec-H, addition of Abs did not influence cytokine production, either in the presence or absence of synthetic oligodeoxynucleotides containing unmethylated cytosine-guanine motifs (CpG). In comparison, Siglec-H functioned as an endocytic receptor and mediated efficient internalization of anti-Siglec-H Abs. By immunizing mice with ovalbumin-conjugated anti-Siglec-H Ab in the presence of CpG, we demonstrate generation of antigen-specific CD8 T cells in vivo. Targeting Siglec-H may therefore be a useful way of delivering antigens to pDC precursors for cross-presentation.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/metabolism
- Base Sequence
- CD8-Positive T-Lymphocytes/immunology
- Cloning, Molecular
- DNA, Complementary/genetics
- Dendritic Cells/cytology
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Endocytosis/immunology
- Gene Expression
- Hematopoietic Stem Cells/cytology
- Hematopoietic Stem Cells/immunology
- Hematopoietic Stem Cells/metabolism
- Mice
- Mice, Inbred Strains
- Mice, Knockout
- Molecular Sequence Data
- N-Acetylneuraminic Acid/metabolism
- Plasma Cells/cytology
- Plasma Cells/immunology
- Plasma Cells/metabolism
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Homology, Amino Acid
- Sialic Acid Binding Ig-like Lectin 3
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Affiliation(s)
- Jiquan Zhang
- Division of Cell Biology and Immunology, School of Life Sciences, Wellcome Trust Biocentre at Dundee, University of Dundee, Dundee DD1 5EH, United Kingdom
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58
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Stefan M, Claiborn KC, Stasiek E, Chai JH, Ohta T, Longnecker R, Greally JM, Nicholls RD. Genetic mapping of putative Chrna7 and Luzp2 neuronal transcriptional enhancers due to impact of a transgene-insertion and 6.8 Mb deletion in a mouse model of Prader-Willi and Angelman syndromes. BMC Genomics 2005; 6:157. [PMID: 16280085 PMCID: PMC1322230 DOI: 10.1186/1471-2164-6-157] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2005] [Accepted: 11/09/2005] [Indexed: 02/03/2023] Open
Abstract
Background Prader-Willi and Angelman syndrome (PWS and AS) patients typically have an ~5 Mb deletion of human chromosome 15q11-q13, of opposite parental origin. A mouse model of PWS and AS has a transgenic insertion-deletion (TgPWS/TgAS) of chromosome 7B/C subsequent to paternal or maternal inheritance, respectively. In this study, we define the deletion endpoints and examine the impact on expression of flanking genes. Results Using molecular and cytological methods we demonstrate that 13 imprinted and 11 non-imprinted genes are included in the TgPWS/TgAS deletion. Normal expression levels were found in TgPWS brain for genes extending 9.1- or 5.6-Mb centromeric or telomeric of the deletion, respectively. Our molecular cytological studies map the proximal deletion breakpoint between the Luzp2 and Siglec-H loci, and we show that overall mRNA levels of Luzp2 in TgPWS and TgAS brain are significantly reduced by 17%. Intriguingly, 5' Chrna7 shows 1.7-fold decreased levels in TgPWS and TgAS brain whereas there is a ≥15-fold increase in expression in neonatal liver and spleen of these mouse models. By isolating a Chrna7-Tg fusion transcript from TgAS mice, we mapped the telomeric deletion breakpoint in Chrna7 intron 4. Conclusion Based on the extent of the deletion, TgPWS/TgAS mice are models for PWS/AS class I deletions. Other than for the first gene promoters immediately outside the deletion, since genes extending 5.6–9.1 Mb away from each end of the deletion show normal expression levels in TgPWS brain, this indicates that the transgene array does not induce silencing and there are no additional linked rearrangements. Using gene expression, non-coding conserved sequence (NCCS) and synteny data, we have genetically mapped a putative Luzp2 neuronal enhancer responsible for ~33% of allelic transcriptional activity. The Chrna7 results are explained by hypothesizing loss of an essential neuronal transcriptional enhancer required for ~80% of allelic Chrna7 promoter activity, while the Chrna7 promoter is upregulated in B lymphocytes by the transgene immunoglobulin enhancer. The mapping of a putative Chrna7 neuronal enhancer inside the deletion has significant implications for understanding the transcriptional regulation of this schizophrenia-susceptibility candidate gene.
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Affiliation(s)
- Mihaela Stefan
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Pediatrics, Children's Hospital of Pittsburgh, 3460 Fifth Avenue, Pittsburgh, PA 15213
| | - Kathryn C Claiborn
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Edyta Stasiek
- Division of Hematology, Department of Medicine, Albert Einstein College of Medicine, The Bronx, USA
| | - Jing-Hua Chai
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Tohru Ohta
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA
- Health Science University of Hokkaido, Hokkaido, Japan
| | - Richard Longnecker
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Ward 6-231, 303 East Chicago Ave, Chicago, IL 60611, USA
| | - John M Greally
- Division of Hematology, Department of Medicine, Albert Einstein College of Medicine, The Bronx, USA
| | - Robert D Nicholls
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Birth Defects Laboratories, Children's Hospital of Pittsburgh, Room 2109 Rangos Research Center, 3460 Fifth Avenue, Pittsburgh, PA 15213, USA
- Department of Pediatrics, Children's Hospital of Pittsburgh, 3460 Fifth Avenue, Pittsburgh, PA 15213
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59
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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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60
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Tateno H, Crocker PR, Paulson JC. Mouse Siglec-F and human Siglec-8 are functionally convergent paralogs that are selectively expressed on eosinophils and recognize 6′-sulfo-sialyl Lewis X as a preferred glycan ligand. Glycobiology 2005; 15:1125-35. [PMID: 15972893 DOI: 10.1093/glycob/cwi097] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mouse sialic acid-binding immunoglobulin-like lectin F (Siglec-F) is an eosinophil surface receptor, which contains an immunoreceptor tyrosine-based inhibitory motif (ITIM) in its cytoplasmic domain, implicating it as a regulator of cell signaling as documented for other siglecs. Here, we show that the sialoside sequence 6'-sulfo-sLe(X) (Neu5Acalpha2-3[6-SO4] Galbeta1-4[Fucalpha1-3]GlcNAc) is a preferred ligand for Siglec-F. In glycan array analysis of 172 glycans, recombinant Siglec-F-Fc chimeras bound with the highest avidity to 6'-sulfo-sLe X. Secondary analysis showed that related structures, sialyl-Lewis X (sLe X) and 6-sulfo-sLe X containing 6-GlcNAc-SO4 showed much lower binding avidity, indicating significant contribution of 6-Gal-SO4 on Siglec-F binding to 6'-sulfo-sLe x. The lectin activity of Siglec-F on mouse eosinophils was "masked" by endogenous cis ligands and could be unmasked by treatment with sialidase. Unmasked Siglec-F mediated mouse eosinophil binding and adhesion to multivalent 6'-sulfo-sLe X structure, and these interactions were inhibited by anti-Siglec-F monoclonal antibody (mAb). Although there is no clear-cut human ortholog of Siglec-F, Siglec-8 is encoded by a paralogous gene that is expressed selectively by human eosinophils and has recently been found to recognize 6'-sulfo-sLe X. These observations suggest that mouse Siglec-F and human Siglec-8 have undergone functional convergence during evolution and implicate a role for the interaction of these siglecs with their preferred 6'-sulfo-sLe X ligand in eosinophil biology.
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MESH Headings
- Animals
- Antibodies, Monoclonal/pharmacology
- Antigens, CD/drug effects
- Antigens, CD/genetics
- Antigens, CD/physiology
- Antigens, Differentiation, B-Lymphocyte/drug effects
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/physiology
- Antigens, Differentiation, Myelomonocytic/drug effects
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/physiology
- CHO Cells
- Cricetinae
- Eosinophils/metabolism
- Humans
- Lectins/drug effects
- Lectins/genetics
- Lectins/physiology
- Lewis X Antigen/analogs & derivatives
- Ligands
- Mice
- Mice, Transgenic
- Microscopy, Fluorescence
- Neuraminidase/metabolism
- Oligosaccharides/metabolism
- Polysaccharides/chemistry
- Polysaccharides/metabolism
- Sialic Acid Binding Immunoglobulin-like Lectins
- Sialyl Lewis X Antigen/analogs & derivatives
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Affiliation(s)
- Hiroaki Tateno
- Department of Molecular Biology, The Scripps Research Institute, San Diego, CA 92037, USA
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61
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Staub E, Rosenthal A, Hinzmann B. Systematic identification of immunoreceptor tyrosine-based inhibitory motifs in the human proteome. Cell Signal 2004; 16:435-56. [PMID: 14709333 DOI: 10.1016/j.cellsig.2003.08.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Immunoreceptor tyrosine-based inhibitory motifs (ITIMs) are short sequences of the consensus (ILV)-x-x-Y-x-(LV) in the cytoplasmic tail of immune receptors. The phosphorylation of tyrosines in ITIMs is known to be an important signalling mechanism regulating the activation of immune cells. The shortness of the motif makes it difficult to predict ITIMs in large protein databases. Simple pattern searches find ITIMs in approximately 30% of the protein sequences in the RefSeq database. The majority are false positive predictions. We propose a new database search strategy for ITIM-bearing transmembrane receptors based on the use of sequence context, i.e. the predictions of signal peptides, transmembrane helices (TMs) and protein domains. Our new protocol allowed us to narrow down the number of potential human ITIM receptors to 109 proteins (0.7% of RefPep). Of these, 36 have been described as ITIM receptors in the literature before. Many ITIMs are conserved between orthologous human and mouse proteins which represent novel ITIM receptor candidates. Publicly available DNA array expression data revealed that ITIM receptors are not exclusively expressed in blood cells. We hypothesise that ITIM signalling is not restricted to immune cells, but also functions in diverse solid organs of mouse and man.
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Affiliation(s)
- Eike Staub
- MetaGen Pharmaceuticals GmbH, Oudenarderstr. 16, 13347, Berlin, Germany.
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62
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Angata T, Margulies EH, Green ED, Varki A. Large-scale sequencing of the CD33-related Siglec gene cluster in five mammalian species reveals rapid evolution by multiple mechanisms. Proc Natl Acad Sci U S A 2004; 101:13251-6. [PMID: 15331780 PMCID: PMC516556 DOI: 10.1073/pnas.0404833101] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Siglecs are a recently discovered family of animal lectins that belong to the Ig superfamily and recognize sialic acids (Sias). CD33-related Siglecs (CD33rSiglecs) are a subgroup with as-yet-unknown functions, characterized by sequence homology, expression on innate immune cells, conserved cytosolic tyrosine-based signaling motifs, and a clustered localization of their genes. To better understand the biology and evolution of CD33rSiglecs, we sequenced and compared the CD33rSiglec gene cluster from multiple mammalian species. Within the sequenced region, the segments containing CD33rSiglec genes showed a lower degree of sequence conservation. In contrast to the adjacent conserved kallikrein-like genes, the CD33rSiglec genes showed extensive species differences, including expansions of gene subsets; gene deletions, including one human-specific loss of a novel functional primate Siglec (Siglec-13); exon shuffling, generating hybrid genes; accelerated accumulation of nonsynonymous substitutions in the Sia-recognition domain; and multiple instances of mutations of an arginine residue essential for Sia recognition in otherwise intact Siglecs. Nonsynonymous differences between human and chimpanzee orthologs showed uneven distribution between the two beta sheets of the Sia-recognition domain, suggesting biased mutation accumulation. These data indicate that CD33rSiglec genes are undergoing rapid evolution via multiple genetic mechanisms, possibly due to an evolutionary "arms race" between hosts and pathogens involving Sia recognition. These studies, which reflect one of the most complete comparative sequence analyses of a rapidly evolving gene cluster, provide a clearer picture of the ortholog status of CD33rSiglecs among primates and rodents and also facilitate rational recommendations regarding their nomenclature.
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Affiliation(s)
- Takashi Angata
- Glycobiology Research and Training Center, University of California at San Diego, La Jolla, CA 92093-0687, USA
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63
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Aizawa H, Zimmermann N, Carrigan PE, Lee JJ, Rothenberg ME, Bochner BS. Molecular analysis of human Siglec-8 orthologs relevant to mouse eosinophils: identification of mouse orthologs of Siglec-5 (mSiglec-F) and Siglec-10 (mSiglec-G). Genomics 2004; 82:521-30. [PMID: 14559209 DOI: 10.1016/s0888-7543(03)00171-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We recently identified a novel human sialic acid binding immunoglobulin-like lectin, Siglec-8, using mRNA from human eosinophils. To search for a mouse Siglec (mSiglec) ortholog of Siglec-8 and other mouse Siglec paralogs, we conducted public database searches with cDNA sequences of human Siglec-5 to -10 and identified two novel mSiglecs. One has significant sequence identity to human Siglec-5 and is a splice variant of mSiglec-F. The other has greatest sequence identity to human Siglec-10 (mSiglec-G). Both mSiglecs have extracellular Ig-like domains and intracellular tyrosine-based motifs. To determine whether these mSiglecs were relevant to mouse eosinophils, RT-PCR and Northern blot analysis were performed. We detected expression of mSiglec-5 (or -F), -10, and -E mRNA in purified mouse eosinophils, but Northern blot data comparing expression in tissues from normal, IL-5 transgenic, and allergen-sensitized and -challenged mice suggest that mSiglec-10 is probably most relevant to mouse eosinophils.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, Differentiation, B-Lymphocyte/chemistry
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/genetics
- DNA, Complementary/analysis
- Databases, Nucleic Acid
- Eosinophils/metabolism
- Humans
- Lectins/chemistry
- Lectins/genetics
- Mice
- Molecular Sequence Data
- Sequence Alignment
- Sequence Homology, Amino Acid
- Sialic Acid Binding Immunoglobulin-like Lectins
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Affiliation(s)
- Hideyuki Aizawa
- Department of Medicine, Division of Allergy and Clinical Immunology, Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224, USA
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Brinkman-Van der Linden ECM, Angata T, Reynolds SA, Powell LD, Hedrick SM, Varki A. CD33/Siglec-3 binding specificity, expression pattern, and consequences of gene deletion in mice. Mol Cell Biol 2003; 23:4199-206. [PMID: 12773563 PMCID: PMC156146 DOI: 10.1128/mcb.23.12.4199-4206.2003] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mouse CD33/Siglec-3 (mCD33) is the apparent ortholog of human CD33/Siglec-3 (hCD33), a member of the Siglec (sialic acid-binding Ig superfamily lectin) family of sialic acid-recognizing cell-surface lectins. We examined the binding specificity and expression pattern of mCD33 and explored its functions by generating mice deficient in this molecule. Like hCD33, mCD33 is expressed on myeloid precursors in the bone marrow, albeit mostly in the more mature stages of the granulocytic lineage. Moreover, unlike hCD33, mCD33 in peripheral blood is primarily expressed on granulocytes. Also, unlike hCD33, mCD33 did not bind to alpha2-3- or alpha2-6-linked sialic acids on lactosamine units. Instead, it showed distinctive sialic acid-dependent binding only to the short O-linked glycans of certain mucins and weak binding to the sialyl-Tn epitope. Binding was enhanced by removal of 9-O-acetyl groups and attenuated by truncation of the glycerol-like side chain of sialic acids. Mice deficient in CD33 were viable and fertile in a controlled-access specific-pathogen-free vivarium, showed no major morphological or histological abnormalities, had no changes in bone marrow or peripheral leukocyte subpopulations, and had very minor differences in biochemical and erythrocyte parameters. Cellular responses to intraperitoneally injected proinflammatory stimulants, as well as subsequent interleukin-6 secretion, were also apparently unaffected. These results indicate substantial species differences in CD33 expression patterns and ligand recognition and suggest functional degeneracy between mCD33 and the other CD33-related Siglec proteins expressed on cells of the myeloid lineage.
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MESH Headings
- Animals
- Antigens, CD/biosynthesis
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/biosynthesis
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Biotinylation
- COS Cells
- Caseins/metabolism
- Cell Lineage
- Enzyme-Linked Immunosorbent Assay
- Epitopes
- Exons
- Gene Deletion
- Granulocytes/metabolism
- Hematopoietic Stem Cells/metabolism
- Humans
- Inflammation
- Lipopolysaccharides/metabolism
- Mice
- Mice, Inbred C57BL
- Models, Genetic
- N-Acetylneuraminic Acid/metabolism
- Protein Binding
- Recombinant Fusion Proteins/metabolism
- Sialic Acid Binding Ig-like Lectin 3
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Alphey MS, Attrill H, Crocker PR, van Aalten DMF. High resolution crystal structures of Siglec-7. Insights into ligand specificity in the Siglec family. J Biol Chem 2003; 278:3372-7. [PMID: 12438315 DOI: 10.1074/jbc.m210602200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sialic acid-binding immunoglobulin-like lectins (Siglecs) recognize sialylated glycoconjugates and play a role in cell-cell recognition. Siglec-7 is expressed on natural killer cells and displays unique ligand binding properties different from other members of the Siglec family. Here we describe the high resolution structures of the N-terminal V-set Ig-like domain of Siglec-7 in two crystal forms, at 1.75 and 1.9 A. The latter crystal form reveals the full structure of this domain and allows us to speculate on the differential ligand binding properties displayed by members of the Siglec family. A fully ordered N-linked glycan is observed, tethered by tight interactions with symmetry-related protein molecules in the crystal. Comparison of the structure with that of sialoadhesin and a model of Siglec-9 shows that the unique preference of Siglec-7 for alpha(2,8)-linked disialic acid is likely to reside in the C-C' loop, which is variable in the Siglec family. In the Siglec-7 structure, the ligand-binding pocket is occupied by a loop of a symmetry-related molecule, mimicking the interactions with sialic acid.
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Affiliation(s)
- Magnus S Alphey
- Division of Cell Biology and Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
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66
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Abstract
Recent studies of the major cell types involved in the initiation and progression of allergic inflammation have revealed that they express an unexpectedly large number of surface receptors that inhibit the release of proinflammatory mediators from mast cells and basophils in vitro. Moreover, analyses of animals deficient in some of these receptors, for example, Fc(gamma)RIIB, gp49B1 and paired Ig-like receptor (PIR)-B, have shown that the molecules indeed suppress allergic responses driven by the adaptive immune response in vivo. These findings support the emerging concept that allergic diseases are caused not only by excessive activation of cells but also from deficiencies in receptors that suppress these activation responses.
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Affiliation(s)
- Howard R Katz
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
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67
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Connolly NP, Jones M, Watt SM. Human Siglec-5: tissue distribution, novel isoforms and domain specificities for sialic acid-dependent ligand interactions. Br J Haematol 2002; 119:221-38. [PMID: 12358929 DOI: 10.1046/j.1365-2141.2002.03808.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Human Siglec-5 is a sialic acid binding immunoglobulin (Ig)-like lectin (Siglec), comprising one N-terminal IgV-SET domain followed by three IgC2-SET domains, and a cytoplasmic domain with ITIM and SAP motifs which regulate cell signalling. We report the differential distribution of hSiglec-5 on neutrophil and macrophage subsets in tissues using monoclonal antibodies, 1A5 and 2H8, which require the first IgC2-SET domain for binding. Interestingly, hSiglec-5 was especially prominent on macrophages in reactive lymph nodes. We have identified four isoforms of hSiglec-5 possessing three (hSiglec-5-3L and -3C) or four (hSiglec-5-4L and -4S) extracellular domains linked to long (hSiglec-5-3L and -4L) or short (hSiglec-5-4S) cytoplasmic tails or existing as a soluble isoform (hSiglec-5-3C). hSiglec-5-4L has the broadest tissue distribution, being detected in adult spleen, thymus, lymph node, peripheral blood leucocytes and bone marrow, and in fetal lung and liver. A soluble Fc chimaeric protein containing the hSiglec-5-4L extracellular domain binds in a sialic acid-dependent manner to glycophorin A on human erythrocytes and to alpha2-3- and alpha2-6-sialyllactose moieties. Domain deletion mutants of hSiglec-5(D1-4)-Fc reveal that the first three IgC2-SET domains are required for optimal binding, with adhesion being abolished if the first IgC2-SET domain is deleted. This indicates that each hSiglec-5 isoform will interact with sialic acid ligands and provides the first step towards defining structure-function relationships of hSiglec-5 isoforms.
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MESH Headings
- Amino Acid Sequence
- Antibodies, Monoclonal/metabolism
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/metabolism
- Chimera
- Enzyme-Linked Immunosorbent Assay/methods
- Epitopes
- Erythrocytes/metabolism
- Hematopoietic Stem Cells/metabolism
- Humans
- Lectins/chemistry
- Lectins/genetics
- Lectins/metabolism
- Macrophages/metabolism
- Molecular Sequence Data
- Monocytes/metabolism
- N-Acetylneuraminic Acid/metabolism
- Neutrophils/metabolism
- Protein Isoforms/chemistry
- Reverse Transcriptase Polymerase Chain Reaction
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Affiliation(s)
- Nicholas P Connolly
- National Blood Service, Stem Cell Laboratory, National Blood Service Oxford Centre, John Radcliffe Hospital, Oxford, UK
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Collins BE, Blixt O, Bovin NV, Danzer CP, Chui D, Marth JD, Nitschke L, Paulson JC. Constitutively unmasked CD22 on B cells of ST6Gal I knockout mice: novel sialoside probe for murine CD22. Glycobiology 2002; 12:563-71. [PMID: 12213789 DOI: 10.1093/glycob/cwf067] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The interaction of CD22 with glycoprotein ligands bearing the Siaalpha2,6Gal-R sequence is believed to modulate its function as a regulator of B cell signaling. Although a commercial sialoside-polyacrylamide (PAA) probe, NeuAc- alpha2,6Gal-PAA, has facilitated studies on ligand binding by human CD22, murine CD22 binds instead with high affinity to NeuGcalpha2,6Gal-R. A multivalent probe with this sequence was constructed to facilitate investigations of ligand binding in CD22 function using genetically defined murine models. The probe is based on the sialoside-PAA platform, which is then biotinylated for easy detection. A series of sialoside probes were constructed with two different length linker arms between the sialoside and the backbone and three different sialoside to PAA molar ratios. The NeuGcalpha2,6Gal-PAA probe is specific for CD22: it binds to sialidase-treated B cells of wild-type mice but not B cells of CD22-null mice. Additionally, because the probe only binds to sialidase-treated wild-type cells, it confirms that CD22 is constitutively "masked" on most B cells from wild-type mice by binding to ligands in cis. In contrast, the probe bound equally well to native or sialidase-treated B cells from the immunocompromised ligand-deficient ST6Gal I knockout mice, demonstrating that CD22 is constitutively "unmasked" in these cells.
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Affiliation(s)
- Brian E Collins
- Department of Molecular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., MEM-L71, La Jolla, CA 92075, USA
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69
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Angata T, Kerr SC, Greaves DR, Varki NM, Crocker PR, Varki A. Cloning and characterization of human Siglec-11. A recently evolved signaling molecule that can interact with SHP-1 and SHP-2 and is expressed by tissue macrophages, including brain microglia. J Biol Chem 2002; 277:24466-74. [PMID: 11986327 DOI: 10.1074/jbc.m202833200] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Siglecs are sialic acid-recognizing animal lectins of the immunoglobulin superfamily. We have cloned and characterized a novel human molecule, Siglec-11, that belongs to the subgroup of CD33/Siglec-3-related Siglecs. As with others in this subgroup, the cytosolic domain of Siglec-11 is phosphorylated at tyrosine residue(s) upon pervanadate treatment of cells and then recruits the protein-tyrosine phosphatases SHP-1 and SHP-2. However, Siglec-11 has several novel features relative to the other CD33/Siglec-3-related Siglecs. First, it binds specifically to alpha2-8-linked sialic acids. Second, unlike other CD33/Siglec-3-related Siglecs, Siglec-11 was not found on peripheral blood leukocytes. Instead, we observed its expression on macrophages in various tissues, such as liver Kupffer cells. Third, it was also expressed on brain microglia, thus becoming the second Siglec to be found in the nervous system. Fourth, whereas the Siglec-11 gene is on human chromosome 19, it lies outside the previously described CD33/Siglec-3-related Siglec cluster on this chromosome. Fifth, analyses of genome data bases indicate that Siglec-11 has no mouse ortholog and that it is likely to be the last canonical human Siglec to be reported. Finally, although Siglec-11 shows marked sequence similarity to human Siglec-10 in its extracellular domain, the cytosolic tail appears only distantly related. Analysis of genomic regions surrounding the Siglec-11 gene suggests that it is actually a chimeric molecule that arose from relatively recent gene duplication and recombination events, involving the extracellular domain of a closely related ancestral Siglec gene (which subsequently became a pseudogene) and a transmembrane and cytosolic tail derived from another ancestral Siglec.
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MESH Headings
- Amino Acid Sequence
- Antigens, CD/analysis
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/analysis
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/metabolism
- Appendix/cytology
- Appendix/metabolism
- Base Sequence
- Brain/physiology
- Cloning, Molecular
- Evolution, Molecular
- Humans
- Intracellular Signaling Peptides and Proteins
- Lectins/chemistry
- Lectins/genetics
- Lectins/metabolism
- Macrophages/physiology
- Membrane Proteins
- Microglia/physiology
- Molecular Sequence Data
- Organ Specificity
- Palatine Tonsil/cytology
- Palatine Tonsil/metabolism
- Protein Tyrosine Phosphatase, Non-Receptor Type 11
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/metabolism
- Pseudogenes
- RNA, Messenger/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Alignment
- Sequence Homology, Amino Acid
- Sialic Acid Binding Ig-like Lectin 3
- Transcription, Genetic
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Affiliation(s)
- Takashi Angata
- Glycobiology Research and Training Center, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0687, USA
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