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.