title: Sequence analysis and identification of new isoform of EP4 receptors in different atlantic salmon tissues (Salmo salar L.) and its role in PGE2 induced immunomodulation in vitro.
abstract: PGE2 plays an important role in a broad spectrum of physiological and pathological processes mediated through a membrane-bound G protein-coupled receptor (GPCR) called EP receptor. In mammals, four subtypes of EP receptor (EP 1-4) are identified and each of them functions through different signal transduction pathways. Orthologous EP receptors have also been identified in other non-mammalian species, such as chicken and zebrafish. EP4 is the only identified PGE2 receptor to date in Atlantic salmon but its tissue distribution and function have not been studied in any detail. In this study, we first sequenced EP4 receptor in different tissues and found that the presence of the 3nt deletion in the 5' untranslated region was accompanied by silent mutation at nt 668. While attempting to amplify the same sequence in TO cells (an Atlantic salmon macrophage-like cell line), we failed to obtain the full-length product. Further investigation revealed different isoform of EP4 receptor in TO cells and we subsequently documented its presence in different Atlantic salmon tissues. These two isoforms of EP4 receptor share high homology in their first half of sequence but differ in the second half part with several deletion segments though the final length of coding sequence is the same for two isoforms. We further studied the immunomodulation effect of PGE2 in TO cells and found that PGE2 inhibited the induction of CXCL-10, CCL-4, IL-8 and IL-1β genes expression in a time dependent manner and without cAMP upregulation.
authors.affiliation: Norwegian University of Life Sciences, Faculty of Veterinary Medicine and Biosciences, Sea Lice Research Centre, P.O. Box 8146 Dep., 0033 Oslo, Norway.
authors.forename: Tz Chun
authors.initials: TC
authors.lastname: Guo
authors.affiliation: Norwegian University of Life Sciences, Faculty of Veterinary Medicine and Biosciences, Sea Lice Research Centre, P.O. Box 8146 Dep., 0033 Oslo, Norway.
authors.forename: Amr Ahmed Abdelrahim
authors.initials: AA
authors.lastname: Gamil
authors.affiliation: European Neuroscience Institute, Synaptic Vesicle Dynamics, 37077 Göttingen, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Koenig
authors.affiliation: Norwegian University of Life Sciences, Faculty of Veterinary Medicine and Biosciences, Sea Lice Research Centre, P.O. Box 8146 Dep., 0033 Oslo, Norway.
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Evensen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D000242:Cyclic AMP / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism* / Q000494:pharmacology; D056747:Immunomodulation / Q000187:drug effects; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D010802:Phylogeny; D020033:Protein Isoforms; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D020317:Salmo salar / Q000145:classification / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015854:Up-Regulation
chemical_list: D020033:Protein Isoforms; D058309:Receptors, Prostaglandin E, EP4 Subtype; D000242:Cyclic AMP; D015232:Dinoprostone
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