title: Molecular aspects, genomic arrangement and immune responsive mRNA expression profiles of two CXC chemokine receptor homologs (CXCR1 and CXCR2) from rock bream, Oplegnathus fasciatus.
abstract: The CXCR1 and CXCR2 are the prototypical receptors and are the only known receptors for mammalian ELR+ (Glu-Leu-Arg) CXC chemokines, including CXCL8 (interleukin 8). These receptors transduce the ELR+ chemokine signals and operate the downstream signaling pathways in inflammation and innate immunity. In this study, we report the identification and characterization of CXCR1 and CXCR2 genes from rock bream fish (OfCXCR1 and OfCXCR2) at the molecular level. The cDNA and genomic DNA sequences of the OfCXCR1 and OfCXCR2 were identified from a transcriptome library and a custom-constructed BAC library, respectively. Both OfCXCR genes consisted of two exons, separated by an intron. The 5'-flanking regions of OfCXCR genes possessed multiple putative transcription factor binding sites related to immune response. The coding sequences of OfCXCR1 and OfCXCR2 encoded putative peptides of 355 and 360 amino acids (aa), respectively. The deduced aa sequences of OfCXCR1 and OfCXCR2 comprised of a G-protein coupled receptors (GPCR) family 1 profile with a GPCR signature and a DRY motif. In addition, seven conserved transmembrane regions were predicted in both OfCXCRs. While our multiple alignment study revealed the functionally significant conserved elements of the OfCXCR1 and OfCXCR2, phylogeny analyses further confirmed their position in teleost sub clade, in which they manifested an evolutionary relatedness with other fish counterparts. Based on comparative analyses, teleost CXC chemokine receptors appear to be distinct from their non-fish orthologs in terms of evolution (both CXCR1 and CXCR2) and genomic organization (CXCR2). Quantitative real-time PCR (qPCR) detected the transcripts of OfCXCR1 and OfCXCR2 in eleven examined tissues, with higher levels in head kidney, kidney and spleen highlighting their crucial importance in immunity. In vitro stimulation of peripheral blood leukocytes (PBLs) with concanavalin A (Con A) resulted in modulation of OfCXCR2 transcription, but not that of OfCXCR1. In addition, the magnitude of the OfCXCR1 and OfCXCR2 transcripts in head kidney and spleen was differentially increased after the in vivo administration of immune stimulants, LPS and poly I:C and in the infection models injected with rock bream irido virus, Edwardsiella tarda and Streptococcus iniae. These lines of evidence suggest that these receptors may play an important role(s) in immune responsive signaling during pathogenesis of rock bream.
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea.
authors.forename: Navaneethaiyer
authors.initials: N
authors.lastname: Umasuthan
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wan
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea.
authors.forename: Kasthuri Saranya
authors.initials: KS
authors.lastname: Revathy
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea.
authors.forename: Ilson
authors.initials: I
authors.lastname: Whang
authors.affiliation: Genetics & Breeding Research Center, National Fisheries Research & Development Institute, Geoje 656-842, Republic of Korea.
authors.forename: Jae Koo
authors.initials: JK
authors.lastname: Noh
authors.affiliation: Aquatic Life Disease Control Division, National Fisheries and Research & Developmental Institute, Busan 619-705, Republic of Korea.
authors.forename: Seokryel
authors.initials: S
authors.lastname: Kim
authors.affiliation: Aquatic Life Disease Control 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 Special Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea. Electronic address: jehee@jejunu.ac.kr.
authors.forename: Jehee
authors.initials: J
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D020609:Edwardsiella tarda / Q000502:physiology; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D007113:Immunity, Innate; D007497:Iridoviridae / Q000502:physiology; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D023062:Receptors, Interleukin-8A / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D023063:Receptors, Interleukin-8B / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment / Q000662:veterinary; D013291:Streptococcus / Q000502:physiology
chemical_list: D029941:Fish Proteins; D012333:RNA, Messenger; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B
keywords: CXC chemokine receptor (CXCR1 or CXCR2); Constitutive expression; Genomic organization; Immune responsive expression; Oplegnathus fasciatus