title: CpG- and LPS-activated MAPK signaling in in vitro cultured salmon (Salmo salar) mononuclear phagocytes.
abstract: The Mitogen-activated protein kinases (MAPK) are involved in transmitting intracellular signals downstream of diverse cell surface receptors and mediate the response to ligands such as growth factors, hormones and cytokines. In addition, MAPK are critically involved in the innate immune response to pathogen-derived substances, commonly referred to as pathogen-associated molecular patterns (PAMPs), such as bacterial lipopolysaccharide (LPS) and bacterial DNA rich in CpG dinucleotides. Currently, a great deal of knowledge is available about the involvement of MAPK in the innate immune response to PAMPs in mammals; however, little is known about the role of the different MAPK classes in the immune response to PAMPs in lower vertebrates. In the current study, p38 phosphorylation was induced by CpG oligonucleotides (ODNs) and LPS in primary salmon mononuclear phagocytes. Pre-treatment of the cells with a p38 inhibitor (SB203580) blocked the PAMP-induced p38 activity and suppressed the upregulation of most of the CpG- and LPS-induced transcripts highlighting the role of this kinase in the salmon innate immune response to PAMPs. In contrast to p38, the phosphorylation of extracellular signal-regulated kinase (ERK), a MAPK involved primarily in response to mitogens, was high in resting cells and, surprisingly, incubation with both CpG and control ODNs downregulated the phospho-ERK levels independently of p38 activation. The basal phospho-ERK level and the CpG-inducible p38 phosphorylation were greatly influenced by the length of in vitro incubation. The basal phospho-ERK level increased gradually throughout a 5-day culture period and was PI3K-dependent as demonstrated by its sensitivity to Wortmannin suggesting it is influenced by growth factors. Overall these data indicate that both basal and PAMP-induced activity of MAPKs might be greatly influenced by the differentiation status of salmon mononuclear phagocytes.
authors.affiliation: The Norwegian College of Fishery Science, University of Tromsø, N-9037 Tromsø, Norway.
authors.forename: Dimitar B
authors.initials: DB
authors.lastname: Iliev
authors.forename: Tom
authors.initials: T
authors.lastname: Hansen
authors.forename: Sven Martin
authors.initials: SM
authors.lastname: Jørgensen
authors.forename: Aleksei
authors.initials: A
authors.lastname: Krasnov
authors.forename: Jorunn B
authors.initials: JB
authors.lastname: Jørgensen
mesh_terms: D000818:Animals; D015153:Blotting, Western / Q000662:veterinary; D002454:Cell Differentiation; D004269:DNA, Bacterial / Q000737:chemistry; D004926:Escherichia coli; D007093:Imidazoles / Q000494:pharmacology; D007113:Immunity, Innate; D007962:Leukocytes / Q000187:drug effects / Q000201:enzymology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D046228:Microarray Analysis / Q000662:veterinary; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D010587:Phagocytosis / Q000187:drug effects; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D020317:Salmo salar / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: C408982:CPG-oligonucleotide; D004269:DNA, Bacterial; D007093:Imidazoles; D008070:Lipopolysaccharides; D009838:Oligodeoxyribonucleotides; D011725:Pyridines; D058539:Phosphatidylinositol 3-Kinase; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580
keywords: Atlantic salmon (Salmo salar); CpG oligodeoxynucleotides (ODNs); DCs; ERK; FBS; HRP; IL-1β; JNK; LPS; Lipopolysaccharide (LPS); M-CSF; MAPK; MAPK kinase; MAPK-activated protein kinase2; MK2; MKK; Mitogen-activated protein kinase (MAPK); Mononuclear phagocytes; NFkB; NRF2; ODNs; PAMPs; PI3K; TLRs; WB; Western blot; c-Jun NH terminal kinase; dendritic cells; eEF2; eukaryotic elongation factor 2; extracellular signal-regulated kinase; fetal bovine serum; horseradish peroxidase; interleukin-1β; lipopolysaccharide; macrophage colony stimulating factor; mitogen-activated protein kinase; nuclear factor (erythroid-derived 2)-like 2; nuclear factor kappaB; oligodeoxynucleotides; pathogen-associated molecular patterns; phosphatidylinositol 3-kinase; the toll-like receptors