鱼类CC趋化因子基因及其系统进化分析

Phylogenetic analysis of CC chemokine genes of fish

CC趋化因子(CC Chemokine)是一类能够促进动物体内炎症部位的各种白细胞的补充、激活和黏附的趋化性细胞因子家族,是鱼类天然免疫系统的重要组成部分。趋化因子也是当今国际鱼类分子免疫学研究的热点之一。本研究通过比较基因组学和生物信息学的方法,分析了虹鳟(Oncorhynchus mykiss)、牙鲆(Paralichthys olivaceus)和斑点叉尾(Ictalurus punctatus)等重要经济鱼类的CC趋化因子基因结构特点和功能,并采用Clustal X的NJ法对所有新的CC趋化因子和先前发表的鱼类趋化因子与其他动物的CC趋化因子进行系统进化分析,建立了3个独特的包含非鱼类CC趋化因子的直向进化同源组。第1个直向进化同源组建立于人的CCL27和CCL28,有丽鱼科(Cichlidae)Melanochromisauratus和Paralabidochromis chilotes的SCYA101、SCYA101a、大西洋鲑(Salmo salar)的CB510320、斑马鱼(Danio rerio)的BI839410、虹鳟的CK11、斑点叉尾的BM027974和BM029630;第2个直向进化同源组是以人类CCL20建立的,包括虹鳟的CK8a、CK8b、斑点叉尾的SCYA112和鸡(Gallus gallus)AAK84434,其中鸡的序列与人的CCL20最相近(与其他鱼类CC趋化因子相比);第3个直向进化同源组是以鸡的XP_424980和蓝(Ictalurus furcatus)的SCYA109建立的。所有其他鱼类CC趋化因子都没有归类到非鱼类CC趋化因子的同源组中。为了进一步分析鱼类CC趋化因子和哺乳类CC趋化因子间的关系,采用Clustal W的非自举检验(Bootstrapping)启发式搜索(heuristic search)比对法对这些CC趋化因子进行归类分析,结果得到7个潜在的直向进化同源组,包括含有4个鱼类CC趋化因子的CCL20直向进化同源组、5个鱼类CC趋化因子的CCL24直向进化同源组、8个鱼类CC趋化因子的CCL22直向进化同源组、4个鱼类CC趋化因子的CCL17直向进化同源组、15个鱼类CC趋化因子的CCL25直向进化同源组,7个鱼类CC趋化因子的CCL27/CCL28和17个鱼类CC趋化因子的CCL19/CCL21直向进化同源组。趋化因子的研究将有助于更好地了解鱼类抗病性与天然免疫性的关系。[中国水产科学,2006,13(1):119-127]

CC chemokines are a superfamily of chemotactic cytokines involved in recruitment, activation and adhesion of a variety of leukocyte types to inflammatory foci, the important component of the innate immune system. In this paper the structure and function of CC chemokine genes from economically important fishes such as rainbow trout （Oncorhynchus rnykiss）, flounder（Paralichthys olivaceus）and catfish were analysed by comparative genomics and bioinformatics methods. Phylogenetic analysis of all the new CC ehemokines and the previously published fish ehemokines using the neighbor joining method allowed the establishment of orthologies of three distinct CC ehemokine groups with non-fish CC chemokines . The first orthology was established with human CCL27 and CCL28. Included within this elade were ciehlid （Melanochromis auratus and Paralabidochromis ehilotes） SCYA101 and SCYA101a, salmon （ Salmo salar） CB510320, zebrafish （ Danio rerio ） BI839410, rainbow trout CKll, channel catfish （ Ictalurus punctatus） BM027974 and BM029630. The second orthology was established with human CCL20. This elade contained the trout CK8a, CK8b, catfish SCYA112, and chicken （Callus gallus ） AAK84434. The chicken sequence was much closer to the human CCL20 than to any of the fish CC chemokines included in the clade. The third orthology was established between chicken XP _ 424980 and blue catfish （ Ictalurus furcatus ） SCYA109. All the other fish CC ehemokines were not grouped into elades containing non-fish CC chemokines. Phylogenetic analysis using Clustal W by heuristic search without bootstrapping was also performed to explore the relationship of fish CC chemokines and mammalian CC chemokines. Altogether, orthologies were suggested for seven groups of fish CC chemokines. Potential orthologies were suggested for CCL20 including Fundulus CN976993, the trout CK8a and CK8b, and the catfish SCYA112. Similarly, orthologies were suggested for CCL24 with five fish CC ehemokines, for CCL22 with eight fish CC chemokines, for CCL17 with at least four fish CC chemokines, for CCL25 with 15 fish CC ehemokines, for CCL27AS;CL28 with seven fish CC ehemokines, and for CCL19/CCL21 with 17 fish CC chemokines. Chemokine data from fish is crucial not only for comparative immunology, but also in efforts to understand and prevent a number of fast-acting diseases prevalent among important aquaculture species. Ongoing work in fish CC chemokines will help better understand the important relationship between fish disease resistance and innate immunity.