Transgenic zebrafish reporter lines reveal conserved Toll-like receptor signaling potential in embryonic myeloid leukocytes and adult immune cell lineages

• Published in: Journal of leukocyte biology Vol. 85; no. 5; pp. 751 - 765
• Main Authors: Hall, Chris, Flores, Maria Vega, Chien, Annie, Davidson, Alan, Crosier, Kathryn, Crosier, Phil
• Format: Journal Article
• Language: English
• Published: United States Society for Leukocyte Biology 01.05.2009
• Subjects: Animals; Animals, Genetically Modified - genetics; Animals, Genetically Modified - immunology; Bacterial Infections - immunology; Danio rerio; Discosoma; Embryo, Nonmammalian - cytology; Embryo, Nonmammalian - immunology; Fluorescent Antibody Technique; Gene Expression Regulation, Developmental; Genes, Reporter; Green Fluorescent Proteins - metabolism; immunity; Leukocytes - immunology; live imaging; macrophages; MyD88; Myeloid Cells - immunology; Myeloid Differentiation Factor 88 - genetics; Myeloid Differentiation Factor 88 - immunology; Myeloid Differentiation Factor 88 - metabolism; neutrophils; Phagocytosis; Promoter Regions, Genetic; Signal Transduction; TLR; Toll-Like Receptors - immunology; Toll-Like Receptors - metabolism; Wound Healing - immunology; Zebrafish - genetics; Zebrafish - immunology
• ISSN: 0741-5400; 1938-3673
• DOI: 10.1189/jlb.0708405

The immune response of a host to an invading pathogen is dependent on the capacity of its immune cell compartment to recognize highly conserved pathogen components using an ancient class of pattern recognition receptors known as Toll‐like receptors (TLRs). Initiation of TLR‐mediated signaling results in the induction of proinflammatory cytokines that help govern the scale and duration of any ensuing response. Specificity for TLR signaling is, in part, a result of the differential recruitment of intracellular adaptor molecules. Of these, MyD88 is required for the majority of TLR signaling. Zebrafish have been shown to possess TLRs and adaptor molecules throughout early development, including MyD88, strongly suggesting conservation of this ancient defense mechanism. However, information about which embryonic cells/tissues possess this conserved signaling potential is lacking. To help define which embryonic cells, in particular, those of the innate immune system, have the potential for MyD88‐dependent, TLR‐mediated signaling, we generated transgenic reporter lines using regulatory elements of the myd88 gene to drive the fluorescent reporters enhanced GFP and Discosoma red fluorescent protein 2 within live zebrafish. These lines possess fluorescently marked cells/tissues consistent with endogenous myd88 expression, including a subset of myeloid leukocytes. These innate immune cells were confirmed to express other TLR adaptors including Mal, trif, and Sarm. Live wound‐healing and infection assays validated the potential of these myd88‐expressing leukocytes to participate in immune responses. These lines will provide a valuable resource for further resolving the contribution of MyD88 to early vertebrate immunity.