造血干/祖细胞（HSPC）是宿主免疫反应的基础，CXCR4是HSPC上的主要趋化因子受体。我们新近研究发现，香鱼两种CXCR4：CXCR4a和CXCR4b可能与炎症状态HSPC稳态调控相关。本项目拟在文献和前期研究基础上，综合采用流式细胞术、培养集落形成单位法、HSPC移植、放射性配体结合试验、Western blot及转录组测序分析等技术方法及辐照或鳗弧菌感染香鱼模型，测定炎症状态下香鱼肾和血液中CXCL12/CXCR4轴的蛋白表达变化，证实脂多糖及CXCL12与CXCR4a和CXCR4b各结构域的结合能力差异，明析CXCR4a阳性和CXCR4b阳性HSPC的增殖、动员、活性和转录组差异。本项目预期阐明香鱼两种CXCR4协同调控HSPC增殖、动员和活性的作用机制，这不仅有助于我们了解鱼类多拷贝基因的功能分化，也有助于我们理解脊椎动物免疫系统的进化。

Hematopoietic stem and progenitor cells (HSPC) are the founder cells for animal immune responses, and CXCR4 is thought to be the main chemokine receptor on HSPC surface. Our recent studies show that ayu (Plecoglossus altivelis) CXCR4a and CXCR4b are possibly implicated in the regulation of HSPC homeostasis under inflammatory conditions. The present project aims to illustrate the synergic regulatory roles of ayu CXCR4a and CXCR4b in mediating the proliferation, mobilization and biological activity of HSPC by using methods such as flow cytometry, colony-forming unit-culture, HSPC transplantation, radio ligand binding assay, Western blot, transcriptome analysis, and irradiated or Vibrio anguillarum infected ayu models. Firstly, we will investigate the changes of head kidney and blood protein levels regarding the CXCL12/CXCR4 axis under normal and inflammatory conditions. Besides, we will determine the binding capacity of different domains of CXCR4a and CXCR4b with LPS or CXCL12. Finally, we will elucidate the differences in the proliferation, mobilization and biological activity as well as in transcriptome between CXCR4a positive and CXCR4b positive HSPC. Through this project, we will elaborate the functional differentiation of CXCR4a and CXCR4b on regulating HSPC homeostasis in ayu, hoping to enrich the knowledge of fish immunology. Our project will not only be helpful for us to understand the subfunctionalization of fish multiple-copy genes, but also to better understand the evolution of vertebrate immune system.