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: 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.Immunity 09/2008; 29(2):228-37. DOI:10.1016/j.immuni.2008.05.018 · 19.75 Impact Factor
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ABSTRACT: Development of the vertebrate blood lineages is complex, with multiple waves of hematopoietic precursors arising in different embryonic locations. Monopotent, or primitive, precursors first give rise to embryonic macrophages or erythrocytes. Multipotent, or definitive, precursors are subsequently generated to produce the adult hematopoietic lineages. In both the zebrafish and the mouse, the first definitive precursors are committed erythromyeloid progenitors (EMPs) that lack lymphoid differentiation potential. We have previously shown that zebrafish EMPs arise in the posterior blood island independently from hematopoietic stem cells (HSCs). In this report, we demonstrate that a fourth wave of hematopoietic precursors arises slightly later in the zebrafish aorta/gonad/mesonephros (AGM) equivalent. We have identified and prospectively isolated these cells by CD41 (itga2b) and cmyb expression. Unlike EMPs, CD41(+) AGM cells colonize the thymus to generate rag2(+) T lymphocyte precursors. Timelapse imaging and lineage tracing analyses demonstrate that AGM-derived precursors use a previously undescribed migration pathway along the pronephric tubules to initiate adult hematopoiesis in the developing kidney, the teleostean equivalent of mammalian bone marrow. Finally, we have analyzed the gene expression profiles of EMPs and AGM precursors to better understand the molecular cues that pattern the first definitive hematopoietic cells in the embryo. Together, these studies suggest that expression of CD41 and cmyb marks nascent HSCs in the zebrafish AGM, and provide the means to further dissect HSC generation and function in the early vertebrate embryo.Development 06/2008; 135(10):1853-62. DOI:10.1242/dev.015297 · 6.27 Impact Factor
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ABSTRACT: Lectins play a crucial role in the innate immunity of invertebrates and vertebrates by recognizing and disposing of pathogens. We obtained the complete cDNA of a C-type lectin (EALec1) from Epinephelus akaara using RACE. The complete EALec1 cDNA sequence was 827 bp. The 5-UTR and 3-UTR were 28 bp and 151 bp, respectively, in length. The sequence also contained a polyadenylation signal AATAAA and a poly(A) tail. The EALec1 cDNA encodes polypeptides with 215 amino acids, including a signal peptide of 31 amino acids. The protein has a cysteine-rich region at the N terminal, a collagenous region characterized by G-X-Y repeats, a neck region, and a typical carbohydrate-recognition domain (CRD), indicating that EALec1 is a collectin. The key recognition positions of this CRD are EPD, isolated for the first time in fish. These are likely the interim types, between mannan-binding lectin and galactose-binding lectin. We evaluated the expression pattern of EALec1 in 12 different tissues using RT-PCR. EALec1 was expressed in all tissues, though at different levels. In addition, we inserted EALec1 into an expression vector (pET-28a) for transformation into the BL21 engineering bacteria. Based on enzyme digestion and sequencing of the positive clone, we successfully constructed the EALec1 recombinant expression vector.Chinese Journal of Oceanology and Limnology 09/2009; 27(3):543-549. DOI:10.1007/s00343-009-9291-z · 0.68 Impact Factor