Interferon regulatory factor 2 plays a positive role in interferon gamma expression in golden pompano, Trachinotus ovatus (Linnaeus 1758).
In fish, interferon (IFN) regulatory factor 2 (IRF2) is a regulator of the type I IFN-dependent immune response, thereby playing a crucial role in innate immunity. However, the specific mechanism by which IRF2 regulates type II IFN in fish remains unclear. In the present study, first, to analyse the potential role of golden pompano (Trachinotus ovatus) IRF2 (ToIRF2) in the immune response, the mRNA level of ToIRF2 was detected by quantitative real-time polymerase chain reaction (qRT-PCR) after parasite infection. ToIRF2 was upregulated at early time points in both local infection sites (skin and gill) and system immune tissues (liver, spleen, and head-kidney) after stimulation with Cryptocaryon irritans. Second, to investigate the modulation effect of ToIRF2 on type II IFN (interferon gamma, IFNγ) expression, a promoter analysis was performed using progressive deletion mutations of ToIFNγ. The expression level of IFNγ-5 was highest among the five truncated mutants in response to ToIRF2, indicating that the core promoter region was located from -189 bp to +120 bp, which included the IRF2 binding sites. Mutation analyses showed that the activity of the ToIFNγ promoter dramatically decreased after the targeted mutation of the M1, M2 or M3 binding sites. Additionally, electrophoretic mobile shift assay (EMSA) confirmed that IRF2 interacted with the M1 binding site in the ToIFNγ promoter region to dominate ToIFNγ expression. Finally, overexpressing ToIRF2 in vitro notably increased ToIFNγ and the transcription of several type II IFN/IRF-based signalling pathway genes. These results suggested that ToIRF2 might be involved in the host defence against C. irritans infection and contribute to a better understanding of the transcriptional mechanisms by which ToIRF2 regulates type II IFN in fish.
['Zhu|Ke-Cheng|KC|', 'Liu|Bao-Suo|BS|', 'Zhang|Nan|N|', 'Guo|Hua-Yang|HY|', 'Guo|Liang|L|', 'Jiang|Shi-Gui|SG|', 'Zhang|Dian-Chang|DC|']
D000818:Animals D001483:Base Sequence D016798:Ciliophora D016770:Ciliophora Infections D005393:Fish Diseases D029941:Fish Proteins D005399:Fishes D020869:Gene Expression Profiling D005786:Gene Expression Regulation D007113:Immunity, Innate D050836:Interferon Regulatory Factor-2 D007371:Interferon-gamma D016415:Sequence Alignment
Trachinotus ovatus IRF2 Type II IFN EMSA Promoter activity