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Stosik M, Tokarz-Deptuła B, Deptuła W. Innate lymphoid cells (ILCs) in teleosts against data on ILCs in humans. FISH & SHELLFISH IMMUNOLOGY 2024; 146:109415. [PMID: 38296004 DOI: 10.1016/j.fsi.2024.109415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 02/13/2024]
Abstract
It is assumed that cells corresponding to innate lymphoid cells (ILCs) in humans, in addition to lymphoid tissue inducer cells (LTi), are also found in teleosts. In this systematic group of organisms, however, they are a poorly understood cell population. In contrast to the data on ILCs in humans, which also remain incomplete despite advanced research, in teleosts, these cells require much more attention. ILCs in teleosts have been presented as cells that may be evolutionary precursors of NK cells or ILCs identified in mammals, including humans. It is a highly heterogeneous group of cells in both humans and fish and their properties, as revealed by studies in humans, are most likely to remain strictly dependent on the location of these cells and the physiological state of the individual from which they originate. They form a bridge between innate and adaptive immunity. The premise of this paper is to review the current knowledge of ILCs in teleosts, taking into account data on similar cells in humans. A review of the knowledge concerning these particular cells, elements of innate immunity mechanisms as equivalent to, or perhaps dominant over, adaptive immunity mechanisms in teleosts, as presented, may inspire the need for further research.
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Affiliation(s)
- Michał Stosik
- Institute of Biological Sciences, University of Zielona Góra, Poland
| | | | - Wiesław Deptuła
- Institute of Veterinary Medicine, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Poland
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2
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Dornburg A, Yoder JA. On the relationship between extant innate immune receptors and the evolutionary origins of jawed vertebrate adaptive immunity. Immunogenetics 2022; 74:111-128. [PMID: 34981186 DOI: 10.1007/s00251-021-01232-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 11/01/2021] [Indexed: 01/17/2023]
Abstract
For over half a century, deciphering the origins of the genomic loci that form the jawed vertebrate adaptive immune response has been a major topic in comparative immunogenetics. Vertebrate adaptive immunity relies on an extensive and highly diverse repertoire of tandem arrays of variable (V), diversity (D), and joining (J) gene segments that recombine to produce different immunoglobulin (Ig) and T cell receptor (TCR) genes. The current consensus is that a recombination-activating gene (RAG)-like transposon invaded an exon of an ancient innate immune VJ-bearing receptor, giving rise to the extant diversity of Ig and TCR loci across jawed vertebrates. However, a model for the evolutionary relationships between extant non-recombining innate immune receptors and the V(D)J receptors of the jawed vertebrate adaptive immune system has only recently begun to come into focus. In this review, we provide an overview of non-recombining VJ genes, including CD8β, CD79b, natural cytotoxicity receptor 3 (NCR3/NKp30), putative remnants of an antigen receptor precursor (PRARPs), and the multigene family of signal-regulatory proteins (SIRPs), that play a wide range of roles in immune function. We then focus in detail on the VJ-containing novel immune-type receptors (NITRs) from ray-finned fishes, as recent work has indicated that these genes are at least 50 million years older than originally thought. We conclude by providing a conceptual model of the evolutionary origins and phylogenetic distribution of known VJ-containing innate immune receptors, highlighting opportunities for future comparative research that are empowered by this emerging evolutionary perspective.
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Affiliation(s)
- Alex Dornburg
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, NC, USA.
| | - Jeffrey A Yoder
- Department of Molecular Biomedical Sciences, North Carolina State University, 1060 William Moore Drive, Raleigh, NC, USA.
- Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA.
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA.
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3
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Holosteans contextualize the role of the teleost genome duplication in promoting the rise of evolutionary novelties in the ray-finned fish innate immune system. Immunogenetics 2021; 73:479-497. [PMID: 34510270 DOI: 10.1007/s00251-021-01225-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Accepted: 08/06/2021] [Indexed: 01/16/2023]
Abstract
Over 99% of ray-finned fishes (Actinopterygii) are teleosts, a clade that comprises half of all living vertebrate species that have diversified across virtually all fresh and saltwater ecosystems. This ecological breadth raises the question of how the immunogenetic diversity required to persist under heterogeneous pathogen pressures evolved. The teleost genome duplication (TGD) has been hypothesized as the evolutionary event that provided the substrate for rapid genomic evolution and innovation. However, studies of putative teleost-specific innate immune receptors have been largely limited to comparisons either among teleosts or between teleosts and distantly related vertebrate clades such as tetrapods. Here we describe and characterize the receptor diversity of two clustered innate immune gene families in the teleost sister lineage: Holostei (bowfin and gars). Using genomic and transcriptomic data, we provide a detailed investigation of the phylogenetic history and conserved synteny of gene clusters encoding diverse immunoglobulin domain-containing proteins (DICPs) and novel immune-type receptors (NITRs). These data demonstrate an ancient linkage of DICPs to the major histocompatibility complex (MHC) and reveal an evolutionary origin of NITR variable-joining (VJ) exons that predate the TGD by at least 50 million years. Further characterizing the receptor diversity of Holostean DICPs and NITRs illuminates a sequence diversity that rivals the diversity of these innate immune receptor families in many teleosts. Taken together, our findings provide important historical context for the evolution of these gene families that challenge prevailing expectations concerning the consequences of the TGD during actinopterygiian evolution.
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Gao FX, Lu WJ, Wang Y, Zhang QY, Zhang YB, Mou CY, Li Z, Zhang XJ, Liu CW, Zhou L, Gui JF. Differential expression and functional diversification of diverse immunoglobulin domain-containing protein (DICP) family in three gynogenetic clones of gibel carp. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 84:396-407. [PMID: 29555550 DOI: 10.1016/j.dci.2018.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 03/15/2018] [Indexed: 06/08/2023]
Abstract
Diverse immunoglobulin (Ig) domain-containing protein (DICP) family is a novel bony fish-specific multi-gene family encoding diversified immune receptors. However, their function and the implication of binding partners remain unknown. In this study, we first identified 28 DICPs from three gibel carp gynogenetic clones and revealed their high variability and clone-specific feature. After crucian carp herpesvirus (CaHV) infection, these DICPs were significantly upregulated in head kidney, kidney and spleen. The up-regulation folds in clone A+, F and H were related to the susceptibility to CaHV, progressively increasing from resistant clone to susceptible clone. Overexpression of gibel carp DICPs inhibited interferon (IFN) and viperin promoter-driven luciferase activity. The additions of E. coli extracts and lipid A significantly enhanced the inhibition effect. In addition, gibel carp DICPs can interact with SHP-1 and SHP-2. These findings suggest that gible carp DICPs, as inhibitory receptors, might specifically recognize lipid A, and then interact with SHP-1 and SHP-2 to inhibit the induction of IFN and ISGs.
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Affiliation(s)
- Fan-Xiang Gao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei-Jia Lu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yang Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi-Ya Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi-Bing Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Cheng-Yan Mou
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhi Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Xiao-Juan Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Chao-Wei Liu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Li Zhou
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Jian-Fang Gui
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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5
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Wcisel DJ, Ota T, Litman GW, Yoder JA. Spotted Gar and the Evolution of Innate Immune Receptors. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2017; 328:666-684. [PMID: 28544607 DOI: 10.1002/jez.b.22738] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/23/2017] [Accepted: 02/27/2017] [Indexed: 01/02/2023]
Abstract
The resolution of the gar genome affords an opportunity to examine the diversification and functional specialization of immune effector molecules at a distant and potentially informative point in phylogenetic development. Although innate immunity is effected by a particularly large number of different families of molecules, the focus here is to provide detailed characterization of several families of innate receptors that are encoded in large multigene families, for which orthologous forms can be identified in other species of bony fish but not in other vertebrate groups as well as those for which orthologs are present in other vertebrate species. The results indicate that although teleost fish and the gar, as a holostean reference species, share gene families thought previously to be restricted to the teleost fish, the manner in which the members of the multigene families of innate immune receptors have undergone diversification is different in these two major phylogenetic radiations. It appears that both the total genome duplication and different patterns of genetic selection have influenced the derivation and stabilization of innate immune genes in a substantial manner during the course of vertebrate evolution.
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Affiliation(s)
- Dustin J Wcisel
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Tatsuya Ota
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan
| | - Gary W Litman
- Department of Pediatrics, University of South Florida Morsani College of Medicine, St. Petersburg, Florida, USA
| | - Jeffrey A Yoder
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, North Carolina, USA.,Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina.,Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina, USA
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6
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Brugman S. The zebrafish as a model to study intestinal inflammation. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 64:82-92. [PMID: 26902932 DOI: 10.1016/j.dci.2016.02.020] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 02/16/2016] [Accepted: 02/17/2016] [Indexed: 06/05/2023]
Abstract
Starting out as a model for developmental biology, during the last decade, zebrafish have also gained the attention of the immunologists and oncologists. Due to its small size, high fecundity and full annotation of its genome, the zebrafish is an attractive model system. The fact that fish are transparent early in life combined with the growing list of immune cell reporter fish, enables in vivo tracking of immune responses in a complete organism. Since zebrafish develop ex utero from a fertilized egg, immune development can be monitored from the start of life. Given that several gut functions and immune genes are conserved between zebrafish and mammals, the zebrafish is an interesting model organism to investigate fundamental processes underlying intestinal inflammation and injury. This review will first provide some background on zebrafish intestinal development, bacterial colonization and immunity, showing the similarities and differences compared to mammals. This will be followed by an overview of the existing models for intestinal disease, and concluded by future perspectives in light of the newest technologies and insights.
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Affiliation(s)
- Sylvia Brugman
- Animal Sciences Group, Cell Biology and Immunology, Wageningen University, De Elst 1, room Ee1253, 6708 WD Wageningen, Netherlands.
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7
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Wcisel DJ, Yoder JA. The confounding complexity of innate immune receptors within and between teleost species. FISH & SHELLFISH IMMUNOLOGY 2016; 53:24-34. [PMID: 26997203 DOI: 10.1016/j.fsi.2016.03.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 03/03/2016] [Accepted: 03/15/2016] [Indexed: 06/05/2023]
Abstract
Teleost genomes encode multiple multigene families of immunoglobulin domain-containing innate immune receptors (IIIRs) with unknown function and no clear mammalian orthologs. However, the genomic organization of IIIR gene clusters and the structure and signaling motifs of the proteins they encode are similar to those of mammalian innate immune receptor families such as the killer cell immunoglobulin-like receptors (KIRs), leukocyte immunoglobulin-like receptors (LILRs), Fc receptors, triggering receptors expressed on myeloid cells (TREMs) and CD300s. Teleost IIIRs include novel immune-type receptors (NITRs); diverse immunoglobulin domain containing proteins (DICPs); polymeric immunoglobulin receptor-like proteins (PIGRLs); novel immunoglobulin-like transcripts (NILTs) and leukocyte immune-type receptors (LITRs). The accumulation of genomic sequence data has revealed that IIIR gene clusters in zebrafish display haplotypic and gene content variation. This intraspecific genetic variation, as well as significant interspecific variation, frequently confounds the identification of definitive orthologous IIIR sequences between teleost species. Nevertheless, by defining which teleost lineages encode (and do not encode) different IIIR families, predictions can be made about the presence (or absence) of specific IIIR families in each teleost lineage. It is anticipated that further investigations into available genomic resources and the sequencing of a variety of multiple teleost genomes will identify additional IIIR families and permit the modeling of the evolutionary origins of IIIRs.
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Affiliation(s)
- Dustin J Wcisel
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC 27607, USA
| | - Jeffrey A Yoder
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC 27607, USA; Comparative Medicine Institute, North Carolina State University, Raleigh, NC 27607, USA; Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27607, USA.
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8
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Rodriguez-Nunez I, Wcisel DJ, Litman RT, Litman GW, Yoder JA. The identification of additional zebrafish DICP genes reveals haplotype variation and linkage to MHC class I genes. Immunogenetics 2016; 68:295-312. [PMID: 26801775 DOI: 10.1007/s00251-016-0901-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 01/07/2016] [Indexed: 10/22/2022]
Abstract
Bony fish encode multiple multi-gene families of membrane receptors that are comprised of immunoglobulin (Ig) domains and are predicted to function in innate immunity. One of these families, the diverse immunoglobulin (Ig) domain-containing protein (DICP) genes, maps to three chromosomal loci in zebrafish. Most DICPs possess one or two Ig ectodomains and include membrane-bound and secreted forms. Membrane-bound DICPs include putative inhibitory and activating receptors. Recombinant DICP Ig domains bind lipids with varying specificity, a characteristic shared with mammalian CD300 and TREM family members. Numerous DICP transcripts amplified from different lines of zebrafish did not match the zebrafish reference genome sequence suggesting polymorphic and haplotypic variation. The expression of DICPs in three different lines of zebrafish has been characterized employing PCR-based strategies. Certain DICPs exhibit restricted expression in adult tissues whereas others are expressed ubiquitously. Transcripts of a subset of DICPs can be detected during embryonic development suggesting roles in embryonic immunity or other developmental processes. Transcripts representing 11 previously uncharacterized DICP sequences were identified. The assignment of two of these sequences to an unplaced genomic scaffold resulted in the identification of an alternative DICP haplotype that is linked to a MHC class I Z lineage haplotype on zebrafish chromosome 3. The linkage of DICP and MHC class I genes also is observable in the genomes of the related grass carp (Ctenopharyngodon idellus) and common carp (Cyprinus carpio) suggesting that this is a shared character with the last common Cyprinidae ancestor.
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Affiliation(s)
- Ivan Rodriguez-Nunez
- Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, North Carolina State University, 1060 William Moore Drive, Raleigh, NC, 27607, USA
| | - Dustin J Wcisel
- Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, North Carolina State University, 1060 William Moore Drive, Raleigh, NC, 27607, USA
| | - Ronda T Litman
- Department of Pediatrics, University of South Florida Morsani College of Medicine, USF/ACH Children's Research Institute, 140 7th Avenue South, St. Petersburg, FL, 33701, USA
| | - Gary W Litman
- Department of Pediatrics, University of South Florida Morsani College of Medicine, USF/ACH Children's Research Institute, 140 7th Avenue South, St. Petersburg, FL, 33701, USA.,Department of Molecular Genetics, All Children's Hospital Johns Hopkins Medicine, 501 6th Avenue South, St. Petersburg, FL, 33701, USA
| | - Jeffrey A Yoder
- Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, North Carolina State University, 1060 William Moore Drive, Raleigh, NC, 27607, USA.
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9
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Rodríguez-Nunez I, Wcisel DJ, Litman GW, Yoder JA. Multigene families of immunoglobulin domain-containing innate immune receptors in zebrafish: deciphering the differences. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 46:24-34. [PMID: 24548770 PMCID: PMC4028400 DOI: 10.1016/j.dci.2014.02.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/05/2014] [Accepted: 02/09/2014] [Indexed: 06/03/2023]
Abstract
Five large multigene families encoding innate-type immune receptors that are comprised of immunoglobulin domains have been identified in bony fish, of which four do not possess definable mammalian orthologs. The members of some of the multigene families exhibit unusually extensive patterns of divergence and the individual family members demonstrate marked variation in interspecific comparisons. As a group, the gene families reveal striking differences in domain type and content, mechanisms of intracellular signaling, basic structural features, haplotype and allelic variation and ligand binding. The potential functional roles of these innate immune receptors, their relationships to immune genes in higher vertebrate species and the basis for their adaptive evolution are of broad interest. Ongoing investigations are expected to provide new insight into alternative mechanisms of immunity.
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Affiliation(s)
- Iván Rodríguez-Nunez
- Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27607, USA
| | - Dustin J Wcisel
- Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27607, USA
| | - Gary W Litman
- Department of Pediatrics, University of South Florida College of Medicine, USF/ACH Children's Research Institute, 140 7th Avenue South, St. Petersburg, FL 33701, USA; Department of Molecular Genetics, All Children's Hospital, 501 6th Avenue South, St. Petersburg, FL 33701, USA; H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, USA
| | - Jeffrey A Yoder
- Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27607, USA.
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10
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Identification of natural killer cell receptor genes in the genome of the marsupial Tasmanian devil (Sarcophilus harrisii). Immunogenetics 2012; 65:25-35. [PMID: 23007952 DOI: 10.1007/s00251-012-0643-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 07/30/2012] [Indexed: 10/27/2022]
Abstract
Within the mammalian immune system, natural killer (NK) cells contribute to the first line of defence against infectious agents and tumours. Their activity is regulated, in part, by cell surface NK cell receptors. NK receptors can be divided into two unrelated, but functionally analogous superfamilies based on the structure of their extracellular ligand-binding domains. Receptors belonging to the C-type lectin superfamily are predominantly encoded in the natural killer complex (NKC), while receptors belonging to the immunoglobulin superfamily are predominantly encoded in the leukocyte receptor complex (LRC). Natural killer cell receptors are emerging as a rapidly evolving gene family which can display significant intra- and interspecific variation. To date, most studies have focused on eutherian mammals, with significantly less known about the evolution of these receptors in marsupials. Here, we describe the identification of 43 immunoglobulin domain-containing LRC genes in the genome of the Tasmanian devil (Sarcophilus harrisii), the largest remaining marsupial carnivore and only the second marsupial species to be studied. We also identify orthologs of NKC genes KLRK1, CD69, CLEC4E, CLEC1B, CLEC1A and an ortholog of an opossum NKC receptor. Characterisation of these regions in a second, distantly related marsupial provides new insights into the dynamic evolutionary histories of these receptors in mammals. Understanding the functional role of these genes is also important for the development of therapeutic agents against Devil Facial Tumour Disease, a contagious cancer that threatens the Tasmanian devil with extinction.
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11
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Development and characterization of anti-nitr9 antibodies. Adv Hematol 2012; 2012:596925. [PMID: 23049557 PMCID: PMC3463160 DOI: 10.1155/2012/596925] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 06/13/2012] [Accepted: 06/27/2012] [Indexed: 11/17/2022] Open
Abstract
The novel immune-type receptors (NITRs), which have been described in numerous bony fish species, are encoded by multigene families of inhibitory and activating receptors and are predicted to be functional orthologs to the mammalian natural killer cell receptors (NKRs). Within the zebrafish NITR family, nitr9 is the only gene predicted to encode an activating receptor. However, alternative RNA splicing generates three distinct nitr9 transcripts, each of which encodes a different isoform. Although nitr9 transcripts have been detected in zebrafish lymphocytes, the specific hematopoietic lineage(s) that expresses Nitr9 remains to be determined. In an effort to better understand the role of NITRs in zebrafish immunity, anti-Nitr9 monoclonal antibodies were generated and evaluated for the ability to recognize the three Nitr9 isoforms. The application of these antibodies to flow cytometry should prove to be useful for identifying the specific lymphocyte lineages that express Nitr9 and may permit the isolation of Nitr9-expressing cells that can be directly assessed for cytotoxic (e.g., NK) function.
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12
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Rag1-/- mutant zebrafish demonstrate specific protection following bacterial re-exposure. PLoS One 2012; 7:e44451. [PMID: 22970222 PMCID: PMC3435260 DOI: 10.1371/journal.pone.0044451] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 08/06/2012] [Indexed: 12/14/2022] Open
Abstract
Background Recombination activation gene 1 deficient (rag1−/−) mutant zebrafish have a reduced lymphocyte-like cell population that lacks functional B and T lymphocytes of the acquired immune system, but includes Natural Killer (NK)-like cells and Non-specific cytotoxic cells (NCC) of the innate immune system. The innate immune system is thought to lack the adaptive characteristics of an acquired immune system that provide enhanced protection to a second exposure of the same pathogen. It has been shown that NK cells have the ability to mediate adaptive immunity to chemical haptens and cytomegalovirus in murine models. In this study we evaluated the ability of rag1−/− mutant zebrafish to mount a protective response to the facultative intracellular fish bacterium Edwardsiella ictaluri. Methodology/Principal Findings Following secondary challenge with a lethal dose of homologous bacteria 4 and 8 weeks after a primary vaccination, rag1−/− mutant zebrafish demonstrated protective immunity. Heterologous bacterial exposures did not provide protection. Adoptive leukocyte transfers from previously exposed mutants conferred protective immunity to naïve mutants when exposed to homologous bacteria. Conclusions/Significance Our findings show that a component of the innate immune system mounted a response that provided significantly increased survival when rag1−/− mutant zebrafish were re-exposed to the same bacteria. Further, adoptive cell transfers demonstrated that kidney interstitial leukocytes from previously exposed rag1−/− mutant zebrafish transferred this protective immunity. This is the first report of any rag1−/− mutant vertebrate mounting a protective secondary immune response to a bacterial pathogen, and demonstrates that a type of zebrafish innate immune cell can mediate adaptive immunity in the absence of T and B cells.
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Cheng SF, Hu YH, Sun BG, Zhang M, Chi H, Sun L. A single immunoglobulin-domain IgSF protein from Sciaenops ocellatus regulates pathogen-induced immune response in a negative manner. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2012; 38:117-127. [PMID: 22564857 DOI: 10.1016/j.dci.2012.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2011] [Revised: 04/23/2012] [Accepted: 04/25/2012] [Indexed: 05/31/2023]
Abstract
The immunoglobulin superfamily (IgSF) is a large group of cell surface proteins that include various immunoregulatory receptors such as novel immune type receptors (NITRs), which are a family of diversified proteins found exclusively in bony fish. In this study, we identified and analyzed an IgSF protein, SoIgSF1, from red drum (Sciaenops ocellatus). SoIgSF1 is composed of 225 amino acid residues and moderately related to teleost NITRs. In silico analysis indicated that SoIgSF1 is a type I transmembrane glycoprotein and contains an N-terminal signal peptide sequence, a single extracellular immunoglobulin V domain, a transmembrane region, and a cytoplasmic region. However, unlike most NITRs, the cytoplasmic region of SoIgSF1 exhibits no consensus inhibitory or stimulatory signaling sequences but has two tyrosine-containing motifs that conform to the right-half sequence of the immunoreceptor tyrosine-based inhibitory motif (ITIM). Quantitative real time RT-PCR analysis showed that SoIgSF1 expression occurred mainly in immune organs and was drastically induced by viral and bacterial infection. Immunofluorescence microscopy indicated that viral infection of head kidney (HK) leukocytes induced surface expression of SoIgSF1, which was able to interact with antibodies against recombinant SoIgSF1. Antibody cross-linking of SoIgSF1 on HK leukocytes inhibited the expression of immune relevant genes and promoted viral and bacterial infection. Taken together, these results indicate that SoIgSF1, though lacking canonical intracellular signaling motifs, is involved in regulation of host immune response during pathogen infection possibly by functioning as a negative signaling receptor through a novel mechanism.
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Affiliation(s)
- Shun-feng Cheng
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Rd., Qingdao, China
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Sameshima S, Nakao M, Somamoto T. Diversity of CD2 subfamily receptors in cyprinid fishes. RESULTS IN IMMUNOLOGY 2012; 2:25-34. [PMID: 24371564 PMCID: PMC3862340 DOI: 10.1016/j.rinim.2012.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 01/18/2012] [Accepted: 01/24/2012] [Indexed: 01/08/2023]
Abstract
CD2 family receptor (CD2f) is evolutionarily conserved and is widely expressed by various types of leukocytes. To elucidate the phylogenetic diversity of the CD2f, we characterized CD2f in teleosts using ginbuna crucian carp and zebrafish. The identified CD2f isoforms of the ginbuna carp (caauCD2f) exhibited high sequence similarity to the mammalian CD2 subsets CD48, CD244, and CD319, but it was difficult to classify them into their respective mammalian CD2f based on sequence similarity, the presence of an immunoreceptor tyrosine-based switch motif (ITSM), and phylogenetic tree analysis. Although the four caauCD2f isoforms share an extracellular domain with quite high identity (83-94% identity at the nucleic acid level), they differ in the number of ITSM motifs in their cytoplasmic tail. RT-PCR and in situ hybridization analyses showed that the caauCD2f isoforms are expressed by different cell populations, suggesting that they, like mammalian CD2f, have diverse roles. Interestingly, immunoglobulin (Ig) domain-like sequences with high identity to caauCD2fs are clustered close together within 0.6 Mbp on zebrafish chromosomes 1 and 2 (at least 8 and 35 sequences, respectively), and many pairs of the Ig domains share more than 90% identity at the amino acid level. Therefore, the teleost CD2fs with considerably high identity have been probably generated from a common ancestral Ig-domain gene by a very recent gene duplication event. These findings suggest that the identified CD2f acquired functional diversification through successive duplications together with the acquisition of ITSM.
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Affiliation(s)
| | | | - Tomonori Somamoto
- Laboratory of Marine Biochemistry, Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
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15
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Montgomery BC, Cortes HD, Mewes-Ares J, Verheijen K, Stafford JL. Teleost IgSF immunoregulatory receptors. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2011; 35:1223-1237. [PMID: 21414352 DOI: 10.1016/j.dci.2011.03.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 01/14/2011] [Accepted: 03/06/2011] [Indexed: 05/30/2023]
Abstract
In all animals innate immunity is the first line of immune defense from invading pathogens. The prototypical innate cellular responses such as phagocytosis, degranulation, and cellular cytotoxicity are elicited by leukocytes in a diverse range of animals including fish, amphibians, birds and mammals reinforcing the importance of such primordial defense mechanisms. In mammals, these responses are intricately controlled and coordinated at the cellular level by distinct subsets of immunoregulatory receptors. Many of these surface proteins belong to the immunoglobulin superfamily and in mammals elaborate immunoregulatory receptor networks play a major role in the control of infectious diseases. Recent examination of teleost immunity has begun to further illustrate the complexities of these receptor networks in lower vertebrates. However, little is known about the mechanisms that control how immunoregulatory receptors influence cellular decision making in ectothermic vertebrates. This review focuses on several families of recently discovered immunoglobulin superfamily members in fish that share structural, phylogenetic and in some cases functional relationships with mammalian immunoregulatory receptors. Further characterization of these teleost innate immune receptor families will provide detailed information regarding the conservation and importance of innate immune defense strategies throughout vertebrate evolution.
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16
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Dobrinski KP, Brown KH, Freeman JL, Lee C. Molecular cytogenetic methodologies and a BAC probe panel resource for genomic analyses in the zebrafish. Methods Cell Biol 2011; 104:237-57. [PMID: 21924167 DOI: 10.1016/b978-0-12-374814-0.00014-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Molecular cytogenetics is a field that emerged in the 1980s, based on a technique referred to as fluorescence in situ hybridization, (FISH). Using FISH methodologies, a specific DNA sequence or collection of DNA fragments may be selectively labeled with a hapten molecule or fluorescent dye and hybridized to denatured chromosomes, interphase cells, or even chromatin fibers. DNA hybridization kinetics permit these labeled probes to anneal to their complementary sequences on such chromosomal DNA preparations allowing for direct visualization of the sequence of interest in the genome being interrogated. If present, the relative chromosomal position of the sequence can sometimes also be ascertained. Progress in molecular cytogenetic research has advanced the genetic characterization of zebrafish models of human diseases as well as assisted with accurate annotation of the zebrafish reference genome by anchoring large DNA fragments to specific chromosome regions. Using the procedures described in this chapter, hundreds of ambiguous zebrafish bacterial artificial chromosome (BAC) clones have already been assigned to individual genetic linkage groups. Molecular cytogenetic techniques can also be used to study gene duplication events and study the molecular mechanisms by which they arise. Moreover, the availability of a new molecular cytogenetic technique, array-based comparative genomic hybridization (aCGH), is now able to identify gains and losses of DNA segments in zebrafish DNA samples in a genome-wide manner and in a single assay.
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Affiliation(s)
- Kimberly P Dobrinski
- Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
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17
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The phylogenetic origins of natural killer receptors and recognition: relationships, possibilities, and realities. Immunogenetics 2010; 63:123-41. [PMID: 21191578 DOI: 10.1007/s00251-010-0506-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 12/16/2010] [Indexed: 12/20/2022]
Abstract
Natural killer (NK) cells affect a form of innate immunity that recognizes and eliminates cells that are infected with certain viruses or have undergone malignant transformation. In mammals, this recognition can be mediated through immunoglobulin- (Ig) and/or lectin-type NK receptors (NKRs). NKR genes in mammals range from minimally polymorphic single-copy genes to complex multigene families that exhibit high levels of haplotypic complexity and exhibit significant interspecific variation. Certain single-copy NKR genes that are present in one mammal are present as expanded multigene families in other mammals. These observations highlight NKRs as one of the most rapidly evolving eukaryotic gene families and likely reflect the influence of pathogens, especially viruses, on their evolution. Although well characterized in human and mice, cytotoxic cells that are functionally similar to NK cells have been identified in species ranging from birds to reptiles, amphibians and fish. Although numerous receptors have been identified in non-mammalian vertebrates that share structural relationships with mammalian NKRs, functionally defining these lower vertebrate molecules as NKRs is confounded by methodological and interpretive complexities. Nevertheless, several lines of evidence suggest that NK-type function or its equivalent has sustained a long evolutionary history throughout vertebrate species.
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18
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Abstract
Novel immune-type receptors (NITRs) are encoded by large multi-gene families and share structural and signaling similarities to mammalian natural killer receptors (NKRs). NITRs have been identified in multiple bony fish species, including zebrafish, and may be restricted to this large taxonomic group. Thirty-nine NITR genes that can be classified into 14 families are encoded on zebrafish chromosomes 7 and 14. Herein, we demonstrate the expression of multiple NITR genes in the zebrafish ovary and during embryogenesis. All 14 families of zebrafish NITRs are expressed in hematopoietic kidney, spleen and intestine as are immunoglobulin and T cell antigen receptors. Furthermore, all 14 families of NITRs are shown to be expressed in the lymphocyte lineage, but not in the myeloid lineage, consistent with the hypothesis that NITRs function as NKRs. Sequence analyses of NITR amplicons identify known alleles and reveal additional alleles within the nitr1, nitr2, nitr3, and nitr5 families, reflecting the recent evolution of this gene family.
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19
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Cannon JP, Dishaw LJ, Haire RN, Litman RT, Ostrov DA, Litman GW. Recognition of additional roles for immunoglobulin domains in immune function. Semin Immunol 2009; 22:17-24. [PMID: 20004115 DOI: 10.1016/j.smim.2009.11.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 11/16/2009] [Indexed: 01/08/2023]
Abstract
Characterization of immune receptors found in phylogenetically disparate species at the genetic, structural and functional levels has provided unique insight into the evolutionary acquisition of immune function. The roles of variable- and intermediate-type immunoglobulin (Ig) domains in direct recognition of ligands and other functions are far wider than previously anticipated. Common mechanisms of multigene family diversification and expansion as well as unique adaptations that relate to function continue to provide unique insight into the numerous patterns, processes and complex interactions that regulate the host response to infectious challenge.
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Affiliation(s)
- John P Cannon
- University of South Florida, Department of Pediatrics, USF/ACH Children's Research Institute, 140 Seventh Avenue South, St. Petersburg, FL 33701, USA.
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20
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Ferraresso S, Kuhl H, Milan M, Ritchie DW, Secombes CJ, Reinhardt R, Bargelloni L. Identification and characterisation of a novel immune-type receptor (NITR) gene cluster in the European sea bass, Dicentrarchus labrax, reveals recurrent gene expansion and diversification by positive selection. Immunogenetics 2009; 61:773-88. [PMID: 19851764 PMCID: PMC2921055 DOI: 10.1007/s00251-009-0398-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 09/18/2009] [Indexed: 01/17/2023]
Abstract
In the last decade, a new gene family encoding non-rearranging receptors, called novel immune-type receptors (NITRs), has been discovered in teleost fish. NITRs belong to the immunoglobulin superfamily and represent an extraordinarily divergent and rapidly evolving gene complex. Genomic analysis of a region spanning 270 kb led to the discovery of a NITR gene cluster in the European sea bass (Dicentrarchus labrax). In total, 27 NITR genes and three putative pseudogenes, organised in a tandemly arrayed cluster, were identified. Sea bass NITR genes maintain the three major genomic organisations that appear to be essentially conserved among fish species along with new features presumably involving processes of intron loss, exon deletion and acquisition of new exons. Comparative and evolutionary analyses suggest that these receptors have evolved following a “birth-and-death” model of gene evolution in which duplication events together with lineage-specific gain and loss of individual members contributed to the rapid diversification of individual gene families. In this study, we demonstrate that species-specific gene expansions provide the raw material for diversifying, positive Darwinian selection favouring the evolution of a highly diverse array of molecules.
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Affiliation(s)
- Serena Ferraresso
- Department of Public Health, Comparative Pathology and Veterinary Hygiene, Faculty of Veterinary Medicine, University of Padova, Viale dell'Università 16, 35020 Legnaro, Italy.
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21
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Cannon JP. Plasticity of the immunoglobulin domain in the evolution of immunity. Integr Comp Biol 2009; 49:187-96. [PMID: 21669857 DOI: 10.1093/icb/icp018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Immune receptors are omnipresent in multicellular organisms and comprise a vast array of molecular structures that serve to detect and eliminate pathogenic threats. The immunoglobulin (Ig) domain, a central structural feature of the antigen binding receptors that mediate adaptive immunity in jawed vertebrates, appears to play a particularly widespread role in metazoan immunity. Recent reports also have implicated Ig domains in the immune responses of protostomes such as flies and snails. Our research has focused on understanding the utilization of the Ig domain in the immunity of chordates and has identified numerous multigene families of Ig domain-containing receptors that appear to serve roles distinct from the adaptive antigen-binding receptors. Three families have received particular focus: novel immune-type receptors (NITRs) of bony fish, modular domain immune-type receptors (MDIRs) of cartilaginous fish and variable region-containing chitin-binding proteins (VCBPs) of amphioxus. NITRs and MDIRs are encoded in large multigene families of highly diversified forms and exhibit a striking dichotomy of an apparently ubiquitous presence but extensive diversification of sequence both within and among the particular taxonomic groups in which they are found. Crystal structures of VCBPs and NITRs demonstrate significant similarity to those of antigen-binding receptors but at the same time exhibit key differences that imply acquisition of separate and distinct ligand-binding functions. The tremendous plasticity of the Ig domain makes it a strong focus for studies of evolutionary events that have shaped modern integrated immune systems. Current data are consistent with a model of extremely rapid emergence and divergence of immune receptors, perhaps specific to individual species, as organisms contend with environments in which pathogens are continually selected for variation of their own molecular signatures.
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Affiliation(s)
- John P Cannon
- Children's Research Institute, University of South Florida/All Children's Hospital, 140 Seventh Avenue South, St Petersburg, FL 33701, USA
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Yoder JA. Form, function and phylogenetics of NITRs in bony fish. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2009; 33:135-144. [PMID: 18840463 DOI: 10.1016/j.dci.2008.09.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Accepted: 09/08/2008] [Indexed: 05/26/2023]
Abstract
Novel immune-type receptors (NITRs) are encoded by clusters of multigene families and have been identified in multiple bony fish species. All NITRs possess one extracellular immunoglobulin (Ig) domain of the variable (V) type and recent crystal structures of NITR V domains demonstrate their high degree of similarity to V domains of antigen receptors. Many NITRs possess a second extracellular Ig domain of the intermediate (I) type which helps differentiate NITRs from other V domain receptors. The majority of NITRs are type I transmembrane receptors; however, a small number are predicted to encode secreted proteins. Based on their sequence and structure, NITRs have been proposed to be "functional orthologs" of mammalian natural killer receptors (NKRs). Like NKRs, most NITRs possess short functional motifs permitting their classification as inhibitory or activating. NITRs lacking these motifs are functionally ambiguous. Inhibitory and activating NKRs utilize opposing signaling mechanisms to influence the response of NK cells to target cells; studies employing recombinant NITRs suggest that these signaling pathways are conserved between NKRs and NITRs. An analysis of all published NITR sequences demonstrates the conserved nature of multiple residues within the NITR Ig domains permitting the identification of NITR ESTs from salmon, cod, halibut, lake whitefish and stickleback species. Complete data sets of NITRs from the sequencing of the zebrafish and medaka genomes provide insight into the evolution of the NITRs within bony fish species. It is likely that all teleost species encode NITRs which function within innate immunity to regulate cell mediated cytotoxicity.
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Affiliation(s)
- Jeffrey A Yoder
- Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA.
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A bony fish immunological receptor of the NITR multigene family mediates allogeneic recognition. Immunity 2008; 29:228-37. [PMID: 18674935 DOI: 10.1016/j.immuni.2008.05.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 04/30/2008] [Accepted: 05/13/2008] [Indexed: 11/21/2022]
Abstract
Novel immune-type receptors (NITRs) comprise an exceptionally large, diversified family of activating and inhibitory receptors that has been identified in bony fish. Here, we characterized the structure of an activating NITR that is expressed by a cytotoxic natural killer (NK)-like cell line and that specifically binds an allogeneic B cell target. A single amino acid residue within the NITR immunoglobulin variable (V)-type domain accounts for specificity of the interaction. Structures solved by X-ray crystallography revealed that the V-type domains of NITRs form homodimers resembling rearranging antigen-binding receptor heterodimers. CDR1 elements of both subunits of NITR dimers form ligand-binding surfaces that determine specificity for the nonself target. In the evolution of immune function, it appears that a specific NK type of innate recognition may be mediated by a complex germline multigene family of V structures resembling those that are somatically diversified in adaptive immunological responses.
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Desai S, Heffelfinger AK, Orcutt TM, Litman GW, Yoder JA. The medaka novel immune-type receptor (NITR) gene clusters reveal an extraordinary degree of divergence in variable domains. BMC Evol Biol 2008; 8:177. [PMID: 18565225 PMCID: PMC2442602 DOI: 10.1186/1471-2148-8-177] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Accepted: 06/19/2008] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Novel immune-type receptor (NITR) genes are members of diversified multigene families that are found in bony fish and encode type I transmembrane proteins containing one or two extracellular immunoglobulin (Ig) domains. The majority of NITRs can be classified as inhibitory receptors that possess cytoplasmic immunoreceptor tyrosine-based inhibition motifs (ITIMs). A much smaller number of NITRs can be classified as activating receptors by the lack of cytoplasmic ITIMs and presence of a positively charged residue within their transmembrane domain, which permits partnering with an activating adaptor protein. RESULTS Forty-four NITR genes in medaka (Oryzias latipes) are located in three gene clusters on chromosomes 10, 18 and 21 and can be organized into 24 families including inhibitory and activating forms. The particularly large dataset acquired in medaka makes direct comparison possible to another complete dataset acquired in zebrafish in which NITRs are localized in two clusters on different chromosomes. The two largest medaka NITR gene clusters share conserved synteny with the two zebrafish NITR gene clusters. Shared synteny between NITRs and CD8A/CD8B is limited but consistent with a potential common ancestry. CONCLUSION Comprehensive phylogenetic analyses between the complete datasets of NITRs from medaka and zebrafish indicate multiple species-specific expansions of different families of NITRs. The patterns of sequence variation among gene family members are consistent with recent birth-and-death events. Similar effects have been observed with mammalian immunoglobulin (Ig), T cell antigen receptor (TCR) and killer cell immunoglobulin-like receptor (KIR) genes. NITRs likely diverged along an independent pathway from that of the somatically rearranging antigen binding receptors but have undergone parallel evolution of V family diversity.
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Affiliation(s)
- Salil Desai
- Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606, USA.
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