Immune-related, lectin-like receptors are differentially expressed in the myeloid and lymphoid lineages of zebrafish
ABSTRACT The identification of C-type lectin (Group V) natural killer (NK) cell receptors in bony fish has remained elusive. Analyses of the Fugu rubripes genome database failed to identify Group V C-type lectin domains (Zelensky and Gready, BMC Genomics 5:51, 2004) suggesting that bony fish, in general, may lack such receptors. Numerous Group II C-type lectin receptors, which are structurally similar to Group V (NK) receptors, have been characterized in bony fish. By searching the zebrafish genome database we have identified a multi-gene family of Group II immune-related, lectin-like receptors (illrs) whose members possess inhibiting and/or activating signaling motifs typical of Group V NK receptors. Illr genes are differentially expressed in the myeloid and lymphoid lineages, suggesting that they may play important roles in the immune functions of multiple hematopoietic cell lineages.
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ABSTRACT: There has been a revolution in immunology in recent years that has transformed the paradigmatic underpinnings of vertebrate immunology to include the innate immune response. The utilization of basally diverging model systems, like the zebrafish, provides particular insight into the origins and evolution of vertebrate immunity. Investigations aimed at exposing the breadth and complexity of innate immunity using the zebrafish model system have uncovered a broad spectrum of mechanisms, both novel and conserved, that add depth to our understanding of how the immune system functions. Of particular significance is the fact that, during the first 4–6 weeks of development, the zebrafish relies upon innate immunity as its sole mechanism of defense. This unique characteristic, combined with the zebrafish model's inherent advantages including high fecundity, external development, and optical transparency during early development, make the zebrafish a particularly attractive model of study. The establishment of bacterial and viral infectious disease models such as Edwardsiella tarda and snakehead rhabdovirus, respectively, as well as the addition of a wide range of reagents and techniques, including robust forward and reverse genetics approaches, have facilitated the zebrafish model's usage to study of a variety of innate immunity questions. Close examination of the zebrafish's innate immune system reveals a strong degree of sequence conservation in many of areas of study, including but not limited to pattern recognition receptors like the Toll-like receptors, their pathway components, and a variety of cytokines. Studies are currently underway to determine whether such sequence homology equates to functional homology. In addition, a variety of zebrafish genes encoding proteins of unique function are currently under study, including assorted lectins and novel immune type receptors. Close examination of these genes may provide needed insight into the evolutionary history of immunity in vertebrates.12/2007: pages 113-133;
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ABSTRACT: The zebrafish has proven itself as an excellent model to study vertebrate innate immunity. It presents us with possibilities for in vivo imaging of host-pathogen interactions which are unparalleled in mammalian model systems. In addition, its suitability for genetic approaches is providing new insights on the mechanisms underlying the innate immune response. Here, we review the pattern recognition receptors that identify invading microbes, as well as the innate immune effector mechanisms that they activate in zebrafish embryos. We compare the current knowledge about these processes in mammalian models and zebrafish and discuss recent studies using zebrafish infection models that have advanced our general understanding of the innate immune system. Furthermore, we use transcriptome analysis of zebrafish infected with E. tarda, S. typhimurium, and M. marinum to visualize the gene expression profiles resulting from these infections. Our data illustrate that the two acute disease-causing pathogens, E. tarda and S. typhimurium, elicit a highly similar proinflammatory gene induction profile, while the chronic disease-causing pathogen, M. marinum, induces a weaker and delayed innate immune response.Advances in Hematology 07/2012; 2012:159807. DOI:10.1155/2012/159807