The zebrafish reveals dependence of the mast cell lineage on Notch signaling in vivo

Abstract

We used the opportunities afforded by the zebrafish to determine upstream pathways regulating mast cell development in vivo and identify their cellular origin. Colocalization studies demonstrated zebrafish notch receptor expression in cells expressing carboxypeptidase A5 (cpa5), a zebrafish mast cell-specific marker. Inhibition of the Notch pathway resulted in decreased cpa5 expression in mindbomb mutants and wild-type embryos treated with the ␥-secretase inhibitor, Compound E. A series of morpholino knockdown studies specifically identified notch1b and gata2 as the critical factors regulating mast cell fate. Moreover, hsp70::GAL4;UAS::nicd1a transgenic embryos overexpressing an activated form of notch1, nicd1a, displayed increased cpa5, gata2, and pu.1 expression. This increase in cpa5 expression could be reversed and reduced below baseline levels in a dose-dependent manner using Compound E. Finally, evidence that cpa5 expression colocalizes with lmo2 in the absence of IntroductionMast cells are best known for their role in acute and chronic allergic reactions; however, they also function as a crucial component in both innate and acquired immune responses 1 as well as solid tumor and leukemia progression. 2,3 Mast cells delineate from hematopoietic stem cells (HSCs) in the bone marrow but, unlike other blood cells, enter circulation as progenitors. They only complete maturation in resident tissues, which greatly hinders accurate lineage tracing studies in traditional mammalian models. 1 We have been using the zebrafish model to study mast cell development and, specifically, the transcriptional regulation of mast cell lineage commitment. The zebrafish is a highly efficient model system for studying blood cell development. 4-6 All of the major hematopoietic cellular lineages studied to date have zebrafish counterparts, and the fundamental genetic mechanisms that control hematopoiesis are well conserved. 4,7,8 We first described a mast cell counterpart in the zebrafish 9 and subsequently showed conserved roles of these cells in adaptive and innate responses to inflammatory stimuli. 10 Zebrafish carboxypeptidase a5 (cpa5) was identified as a zebrafish mast cell-specific marker, and gata2 and pu.1 were found to be the key transcription factors required for early mast cell lineage commitment in keeping with studies in mammalian systems. 9,11,12 The Notch signaling pathway is a critical regulator of cell fate determination conserved through evolution. Aberrant Notch signaling is associated with a wide range of human disorders from developmental syndromes to cancer. 13 Notch signaling is involved in the fate determination of a variety of cell types, including hematopoietic cells where it participates in differentiation, proliferation, and apoptosis. 14 In mammals, the Notch pathway consists of 4 Notch genes (Notch1-4), which encode transmembrane receptor proteins. These receptors are activated by 5 ligands encoded by the Delta and Serrate/Jagged gene families: Delta-like1, (Dll1), Dll3, Dll4, Jagged 1 (Jag1), and Jag2...

Notch Signaling Enhances FcεRI-Mediated Cytokine Production by Mast Cells through Direct and Indirect Mechanisms

“…Thus, the enhancing effect of N2 ICD on cytokine production was modest in BMMCs, probably due to the adverse effect of the excessive signaling caused by overexpression of N2 ICD . Although Da'as et al (42) have reported that zebrafish notch1b regulates mast cell development through gata2, previous reports by Sakata-Yanagimoto et al (16,17) and our results indicate that mouse Notch2 but not Notch1 is involved in mast cell development. Notch2 signaling-induced downregulation of SHIP-1 may contribute to the differentiation of mast cells and the enhancement of multiple cytokine production in mice.…”

Tween‐80 and impurity induce anaphylactoid reaction in zebrafish

“…According to the literature, zebrafish early mast cells could be distinguished at 28 hpf (Da'as et al ., ; Dobson et al ., ). In the initial assay development, we measured tryptase relative activity in zebrafish at six various developmental stages: 2, 3, 4, 5, 6 and 7 dpf in a microplate‐based assay using BAPNA as a substrate and found that tryptase activity increased as zebrafish developed, indicating that tryptase is measurable in larval zebrafish (Fig.…”

“…Zebrafish mast cells have similar structure and functions to mammals, and are involved in the body's immune response and allergic reaction (Dobson et al ., ). Zebrafish has been used as a model to study mast cell development and functions (Da'as et al ., ; Dobson et al ., ). Da'as et al .…”

Mast cell plasticity and sphingosine-1-phosphate in immunity, inflammation and cancer

“…Moreover, Notch2 signaling in MC is required for proper localization of intestinal MC during murine parasitic infection [24]. A transgenic zebrafish line overexpressing notch1a recapitulated the MC accumulation observed in human systemic mastocytosis and was abrogated upon Notch pathway inhibition, also suggesting the dependence of human MC lineage on Notch signaling [25]. Although both gata2 and pu.1 are critical to MC lineage commitment, gata2 is controlled by the Notch signaling pathway, whereas pu.1 appears to be more selectively regulated by notch1a [25].…”

“…A transgenic zebrafish line overexpressing notch1a recapitulated the MC accumulation observed in human systemic mastocytosis and was abrogated upon Notch pathway inhibition, also suggesting the dependence of human MC lineage on Notch signaling [25]. Although both gata2 and pu.1 are critical to MC lineage commitment, gata2 is controlled by the Notch signaling pathway, whereas pu.1 appears to be more selectively regulated by notch1a [25]. A recent study demonstrated that complete gata1 ablation had minimal effects on MC numbers and tissue distribution in adult mice but reduced MC tryptase expression levels [26].…”