Molecular characterization and functional analysis of IRF3 in tilapia (Oreochromis niloticus).
Interferon regulatory factor 3 (IRF3) plays a key role in interferon (IFN) response and binding to the IFN stimulatory response elements (ISREs) within the promoter of IFN and IFN-stimulated genes followed by virus infection. In the current study, we discovered one IRF3 homologue in tilapia genome and analyzed the characterizations and functions of tilapia IRF3. Tilapia IRF3 contains 1368 bp with an ORF of 455 aa. Structurally, tilapia IRF3 protein typically shares the conserved characterizations with other species' IRF3 homologues, displaying conserved DNA-binding domain, IRF association domain, serine-rich C terminal domain, and tryptophan residue cluster. Phylogenetic analysis illustrated that tilapia IRF3 belongs to the IRF3 subfamily. Real-time PCR revealed a broad expression pattern of tilapia IRF3 in various tissues. Subcellular localization analysis showed that tilapia IRF3 mainly resides in the cytoplasm, Western blot demonstrated that IRF3 was distributed in the cytoplasmic fraction. Functionally, IRF3 was found to be transcriptionally up-regulated by the poly I:C stimulation. Moreover, reporter assay elucidated that tilapia IRF3 serves as a regulator in mediating IFN response by increasing the activity of IFN-β and ISRE-containing promoter. These data supported the view that tilapia IRF3 is a potential molecule in IFN immune defense system against viral infection.
Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306, China; Department of Developmental Biology, University of Texas Southwestern Medical Center at Dallas, 6000 Harry Hines Boulevard Dallas, TX, 75390-9133, USA. Electronic address: gu-yifeng@hotmail.com.
Yi-Feng
YF
Gu
Department of Surgical Oncology and Institute of Clinical Medicine, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China; Department of International Medicine, University of Texas Southwestern Medical Center at Dallas, 6000 Harry Hines Boulevard Dallas, TX, 75390-9133, USA.
Qun
Q
Wei
Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306, China.
Shou-Jie
SJ
Tang
Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306, China. Electronic address: xwchen@shou.edu.cn.
Xiao-Wu
XW
Chen
Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306, China. Electronic address: jlzhao@shou.edu.cn.
Jin-Liang
JL
Zhao
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D005393:Fish Diseases / Q000276:immunology*; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D007113:Immunity, Innate / Q000235:genetics; D050838:Interferon Regulatory Factor-3 / Q000235:genetics / Q000378:metabolism*; D016899:Interferon-beta / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D011070:Poly I-C / Q000276:immunology; D020218:Response Elements / Q000235:genetics; D017210:Tilapia / Q000276:immunology*; D015854:Up-Regulation; D014777:Virus Diseases / Q000276:immunology*
D029941:Fish Proteins; D050838:Interferon Regulatory Factor-3; D016899:Interferon-beta; D011070:Poly I-C
IFN (interferon); IRF3 (Interferon regulatory factor 3); ISGs (IFN-stimulated genes); ISRE (Interferon-stimulated response element); Tilapia