title: Genomic characterization of interferon regulatory factor 5 from rock bream (Oplegnathus fasciatus) and its role in antiviral defense.
abstract: The interferon regulatory factor 5 (IRF5) is a key mediator of the Toll-like receptor (TLR)7 and TLR8 signaling pathways. In this study, we describe the identification of IRF5 (Rb-IRF5) from rock bream fish (Oplegnathus fasciatus) and its characteristics features at the genomic and expression levels. The full-length Rb-IRF5 sequence was identified from a cDNA library and its genomic sequence was obtained by screening and sequencing of a bacterial artificial chromosome (BAC) genomic DNA library of rock bream. The genomic sequence is comprised of 8 exons interrupted by 7 introns. The complete coding sequence of Rb-IRF5 is 1497 bp in length and encodes for 498 amino acids. The putative Rb-IRF5 protein consists of 3 important conserved domains: a DNA-binding domain (DBD) at the N-terminus, an IRF-associated domain (IAD), and a virus-activated domain (VAD) at the C-terminus. Based on pairwise sequence analysis, the highest sequence similarity/identity for Rb-IRF5 was observed with the IRF5 gene from turbot fish (>87%) and Japanese flounder (83%). Several important putative transcription factor-binding sites shared by the IRF gene family, including the NF-κB, Ap-1, IRF-1, and ICSBP/ISRE sites, were found in the 5' flanking region of Rb-IRF5. The predicted tertiary structure of the dimerized IAD and VAD of the Rb-IRF5 protein resembled that of its orthologs from humans. In healthy rock bream, the highest constitutive expression of Rb-IRF5 was detected in the liver. After iridovirus and polyinosinic-polycytidylic acid (poly(I:C)) challenge, Rb-IRF5 expression was significantly induced in the head kidney. Furthermore, rock bream recombinant type I interferon (Rb-IFN1) was also found to be an efficient inducer of Rb-IRF5 in a head kidney primary cell culture model. Upon IRF5 transfection, rock bream Mx (Rb-Mx), interferon I (Rb-IFN1) and tumor-necrosis factor α (Rb-TNFα) genes get significantly upregulated in rock bream heart cells. The findings of the present study explain the involvement of Rb-IRF5 in the induction of interferons and pro-inflammatory cytokines and thereby provide a model for how IRF5 modulates immune responses against viral infections in rock bream.
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea.
authors.forename: W D Niroshana
authors.initials: WD
authors.lastname: Wickramaarachchi
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wan
authors.affiliation: Marine and Environmental Institute, Jeju National University, Jeju Special Self-Governing Province 690-814, Republic of Korea.
authors.forename: Bong-Soo
authors.initials: BS
authors.lastname: Lim
authors.affiliation: Marine and Environmental Institute, Jeju National University, Jeju Special Self-Governing Province 690-814, Republic of Korea.
authors.forename: Hyung-Bok
authors.initials: HB
authors.lastname: Jung
authors.affiliation: College of Veterinary Medicine, Chungnam National University, Yuseong-gu, Daejeon 305-764, Republic of Korea.
authors.forename: Mahanama
authors.initials: M
authors.lastname: De Zoysa
authors.affiliation: Pathology Division, National Fisheries and Research & Developmental Institute, Busan 619-705, Republic of Korea.
authors.forename: Myoung-Ae
authors.initials: MA
authors.lastname: Park
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Marine and Environmental Institute, Jeju National University, Jeju Special Self-Governing Province 690-814, Republic of Korea. Electronic address: jehee@jejunu.ac.kr.
authors.forename: Jehee
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea. Electronic address: ilsonwhang@hanmail.net.
authors.forename: Ilson
authors.initials: I
authors.lastname: Whang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D022202:Chromosomes, Artificial, Bacterial; D004266:DNA Virus Infections / Q000276:immunology*; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D060226:Head Kidney / Q000378:metabolism; D050835:Interferon Regulatory Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017994:Iridovirus / Q000276:immunology; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics* / Q000276:immunology* / Q000821:virology; D010802:Phylogeny; D011070:Poly I-C / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment / Q000662:veterinary
chemical_list: D018076:DNA, Complementary; D029941:Fish Proteins; D050835:Interferon Regulatory Factors; D012333:RNA, Messenger; D011070:Poly I-C
keywords: Genomic structure; Immune challenge; Interferon regulatory factor 5; Promoter prediction; Transcriptional analysis