State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
PLoS One. 2013 Apr 4;8(4):e60588. doi: 10.1371/journal.pone.0060588. Print 2013.
Gig2 (grass carp reovirus (GCRV)-induced gene 2) is first identified as a novel fish interferon (IFN)-stimulated gene (ISG). Overexpression of a zebrafish Gig2 gene can protect cultured fish cells from virus infection. In the present study, we identify a novel gene family that is comprised of genes homologous to the previously characterized Gig2. EST/GSS search and in silico cloning identify 190 Gig2 homologous genes in 51 vertebrate species ranged from lampreys to amphibians. Further large-scale search of vertebrate and invertebrate genome databases indicate that Gig2 gene family is specific to non-amniotes including lampreys, sharks/rays, ray-finned fishes and amphibians. Phylogenetic analysis and synteny analysis reveal lineage-specific expansion of Gig2 gene family and also provide valuable evidence for the fish-specific genome duplication (FSGD) hypothesis. Although Gig2 family proteins exhibit no significant sequence similarity to any known proteins, a typical Gig2 protein appears to consist of two conserved parts: an N-terminus that bears very low homology to the catalytic domains of poly(ADP-ribose) polymerases (PARPs), and a novel C-terminal domain that is unique to this gene family. Expression profiling of zebrafish Gig2 family genes shows that some duplicate pairs have diverged in function via acquisition of novel spatial and/or temporal expression under stresses. The specificity of this gene family to non-amniotes might contribute to a large extent to distinct physiology in non-amniote vertebrates.
Gig2（草鱼虹彩病毒诱导基因 2）最初被鉴定为一种新的鱼类干扰素（IFN）刺激基因（ISG）。斑马鱼 Gig2 基因的过表达可以保护培养的鱼类细胞免受病毒感染。在本研究中，我们鉴定了一个新的基因家族，该家族由与先前表征的 Gig2 同源的基因组成。EST/GSS 搜索和计算机克隆在 51 种脊椎动物物种中鉴定出 190 个 Gig2 同源基因，范围从七鳃鳗到两栖动物。对脊椎动物和无脊椎动物基因组数据库的进一步大规模搜索表明，Gig2 基因家族是无羊膜动物特有的，包括七鳃鳗、鲨鱼/鳐鱼、硬骨鱼和两栖动物。系统发育分析和同线性分析揭示了 Gig2 基因家族的谱系特异性扩张，并为鱼类特异性基因组复制（FSGD）假说提供了有价值的证据。尽管 Gig2 家族蛋白与任何已知蛋白没有显著的序列相似性，但典型的 Gig2 蛋白似乎由两个保守部分组成：一个 N 端，与多聚（ADP-核糖）聚合酶（PARPs）的催化结构域具有极低的同源性，和一个独特的新型 C 端结构域，是该基因家族所特有的。斑马鱼 Gig2 家族基因的表达谱显示，一些重复对在受到压力时通过获得新的空间和/或时间表达而在功能上发生了分化。这个基因家族对无羊膜动物的特异性在很大程度上可能有助于无羊膜脊椎动物的独特生理学。
