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A conserved interferon regulation factor 1 (IRF-1) from Pacific oyster Crassostrea gigas functioned as an activator of IFN pathway

Lu, Mengmeng, Yang, Chuanyan, Li, Meijia, Yi, Qilin, Lu, Guangxia, Wu, Yichen, Qu, Chen, Wang, Lingling, Song, Linsheng
Fish & shellfish immunology 2018 v.76 pp. 68-77
Crassostrea gigas, DNA-binding domains, amino acids, cytoplasm, enzyme activity, fish, gene expression, hemocytes, immune response, interferon regulatory factor-1, interferons, luciferase, messenger RNA, open reading frames, oysters, polypeptides, reporter genes, response elements, shellfish, tissues, transcription (genetics), transfection
Interferon regulatory factors (IRFs), a family of transcription factors with a novel helix-turn-helix DNA-binding motif, play important roles in regulating the expression of interferons (IFNs) and IFN-stimulated genes. In the present study, an interferon regulation factor 1 was identified from oyster Crassostrea gigas (designated CgIRF-1), and its immune function was characterized to understand the regulatory mechanism of interferon system against viral infection in invertebrates. The open reading frame (ORF) of CgIRF-1 was 990 bp, encoding a polypeptide of 329 amino acids with a typical IRF domain (also known as DNA-binding domain). The mRNA transcripts of CgIRF-1 were detected in all the tested tissues with the highest expression level in hemocyte. CgIRF-1 protein was distributed in both nucleus and cytoplasm of the oyster hemocyte. The mRNA expression of CgIRF-1 in hemocytes was significantly up-regulated at 48 h after poly (I:C) stimulation (p < 0.05). The recombinant CgIRF-1 (rCgIRF-1) could interact with classically IFN-stimulated response elements (ISRE) in vitro. The relative luciferase activity of interferon-like protein promotor reporter gene (pGL-CgIFNLP promotor) was significantly (p < 0.05) enhanced in HEK293T cell after transfection of CgIRF-1. These results indicated that CgIRF-1 could bind ISRE and regulate the expression of CgIFNLP as a transcriptional regulatory factor, and participated in the antiviral immune response of oysters.