黄颡鱼FTR67基因的克隆及功能研究

鱼类TRIM(Tripartite motif)家族的特异性扩张产生了一个硬骨鱼类特有的亚家族finTRIM (Fish novel TRIM, FTR),为探究finTRIM在黄颡鱼(Tachysurus fulvidraco)先天抗病毒免疫中发挥的作用,文章鉴定了1个与斑马鱼(Danio rerio) FTR67同源性较高的黄颡鱼finTRIM基因,命名为TfFTR67 (Tachysurus fulvidraco FTR67)。系统进化树分析表明, FTR67在有些鱼类物种中发生了基因重复,导致基因拷贝增多。TfFTR67不受SVCV的诱导表达,是一个组成型表达的基因。过量表达TfFTR67抑制poly(I﹕C)及RLR信号分子诱导的干扰素反应,同时促进病毒在细胞中的复制。鉴于TfFTR67与斑马鱼FTR67的表达特征和功能不同,研究结果表明,鱼类FTR67在不同物种中发生了基因重复和功能歧化。

MOLECULAR CLONING AND FUNCTION ANALYSIS OF TACHYSURUS FULVIDRACO FTR67

TRIM (Tripartite motif) proteins play direct antiviral and indirect regulatory roles in vertebrate innate antiviral responses. The independent expansion of fish TRIM family gives rise to a subfamily unique to teleosts, named finTRIM (fish novel TRIM, FTR). In the current study, we identified a yellow catfish finTRIM gene, which is most homologous to zebrafish (Danio rerio) FTR67, thus named TfFTR67 (Tachysurus fulvidraco FTR67). Phylogenetic tree analysis showed that FTR67 has undergone gene duplication in some fish species, resulting in increased gene copies. RT-PCR showed that TfFTR67 is virally inducible and thus is a constitutively expressed gene. Overexpression of TfFTR67 inhibited the interferon response induced by poly(I﹕C) transfection and overexpression of RLR signaling molecules, and also promoted virus replication in fish cells. A previous report has shown that zebrafishFTR67 is induced by virus infection, and overexpression of zebrafish FTR67 enhances fish interferon response. Therefore, yellow catfish FTR67 displays the expression characteristics and function features that are different from those of zebrafish FTR67. In addition, three copies of FTR67 are found in goldfish genome, indicating that there is independent expansion of FTR67 gene in certain fish species. Actually, we do not know whether there is only one copy of FTR67 gene in yellow catfish genome although a single one is found up to now. These data together suggest that fish FTR67 has undergone gene duplication and functional diversification after radiation of fish species.