| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
The chemokine system plays a critical role in mammalian immunity ; however, the role of chemokines, particularly CC chemokines, in hematopoiesis during early development is ill-defined. Until 2004, drCCL1 was the only known zebrafish CC chemokine. Thereafter, more than 50 new CC chemokines have been discovered in the public database ; this is almost twice the number of CC chemokines discovered in humans or mouse. We chose three CC chemokines, i.e., drCCL1, drCCL25L, and drCCL19L, which were thought to be the homologs of human CCL27/CCL28, CCL25, and CCL19, respectively. Gene expression analyses using zebrafish early embryos revealed that drCCL19, drCCL1, and drCCL25L were expressed at different time points, i.e., immediately after fertilization, at 4 h postfertilization (hpf), and at 12 hpf, respectively, indicating that these chemokines are involved in cell migration during early embryogenesis. Whole-mount in situ hybridization using embryos at 20 hpf (segmentation period) demonstrated the gene expression of these chemokines in some regions of the inner cell mass (ICM), which is a hematopoietic tissue from around 16 hpf to 2 or 3 days postfertilization. Furthermore, we also observed gene expression of both drCCL1 and drCCL25L around the thymic primordium and pronephros (corresponding to the human bone marrow). These findings strongly suggested that these chemokines could be involved in the hematopoiesis and/or lymphopoiesis during early development. We are currently generating transgenic zebrafishes in which lymphocytes express green fluorescent protein under the control of lck or rag2 gene promoter, and examining knock-down effects of morpholino oligos that target these chemokine genes on migration of lymphocytes during early development.
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