Center for Informational Biology, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China.
Center for Informational Biology, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China.
Fish Shellfish Immunol. 2020 Feb;97:500-508. doi: 10.1016/j.fsi.2019.12.077. Epub 2019 Dec 25.
Interleukin (IL)-2 belongs to the four-helix bundle cytokine family and plays key roles in growth, survival, activation-induced cell death and differentiation of the immune cells. In cyprinid fish, only common carp interleukin-2 (il2) has been cloned because of relatively low sequence homology between carp Il-2 and its homologs in other fish species. In the present study, the coding sequence of grass carp Il-2 (gcIl-2) was cloned and its identity was verified via bioinformatic analysis. Tissue distribution study showed that grass carp il2 (gcil2) mRNA was expressed in thymus, head kidney and gill with relatively high levels. Recombinant gcIl-2 (rgcIl-2) protein was subsequently prepared by using a prokaryotic expression system followed by a refolding method. The purified rgcIl-2 displayed an ability to stimulate the cell proliferation along with an increased mRNA expression of cd4l but not cd8a, igm or mcsfr in grass carp head kidney leukocytes (HKLs), suggesting the possible involvement of gcIl-2 in T helper (Th) cell proliferation. In the same cell model, rgcIl-2 significantly enhanced mRNA expression of some cytotoxic molecules including perforin-like protein 2, granzyme B-like and Fas ligand, indicating the modulation of cytotoxic cells by gcIl-2 in grass carp HKLs. Besides, gene expression of regulatory T (Treg) cell- and Th1/2 cell-related cytokines or transcription factors was detected in grass carp HKLs treated by rgcIl-2. Results showed that rgcIL2 treatment increased the mRNA expression of foxp3, cd25l, ifng2, il12p35, tbet, tnfa, il2, il4/13a, il4/13b and gata3l in HKLs, implying the regulatory roles of Il-2 in the expression of these immune genes and its possible involvement in differentiation of Treg and Th1/2 cells. These observations together with the related studies in other fishes suggest the existence of cytotoxic cells, Treg and Th1/2 subpopulations in fish species and the functional roles of Il-2 in these cells.
白细胞介素 (IL)-2 属于四螺旋束细胞因子家族，在免疫细胞的生长、存活、激活诱导的细胞死亡和分化中发挥关键作用。在鲤科鱼类中，由于鲤鱼 Il-2 与其他鱼类的同源物之间的序列同源性相对较低，因此仅克隆了普通鲤鱼白细胞介素-2 (il2)。在本研究中，克隆了草鱼白细胞介素-2 (gcIl-2) 的编码序列，并通过生物信息学分析验证了其同一性。组织分布研究表明，草鱼 il2 (gcil2) mRNA 在胸腺、头肾和鳃中表达水平较高。随后，通过原核表达系统和复性方法制备了重组 gcIl-2 (rgcIl-2) 蛋白。纯化的 rgcIl-2 显示出刺激细胞增殖的能力，并增加了草鱼头肾白细胞 (HKLs) 中 cd4l 的 mRNA 表达，但 cd8a、igm 或 mcsfr 没有增加，表明 gcIl-2 可能参与 Th 细胞增殖。在相同的细胞模型中，rgcIl-2 显著增强了一些细胞毒性分子的 mRNA 表达，包括穿孔素样蛋白 2、颗粒酶 B 样和 Fas 配体，表明 gcIl-2 对草鱼 HKLs 中的细胞毒性细胞进行了调节。此外，在草鱼 HKLs 中检测到 rgcIl-2 处理后调节性 T (Treg) 细胞和 Th1/2 细胞相关细胞因子或转录因子的基因表达。结果表明，rgcIL2 处理增加了 HKLs 中 foxp3、cd25l、ifng2、il12p35、tbet、tnfa、il2、il4/13a、il4/13b 和 gata3l 的 mRNA 表达，表明 Il-2 在这些免疫基因表达中的调节作用及其可能参与 Treg 和 Th1/2 细胞的分化。这些观察结果与其他鱼类的相关研究一起表明，鱼类中存在细胞毒性细胞、Treg 和 Th1/2 亚群，以及 Il-2 在这些细胞中的功能作用。
