title: Signalling pathways regulating inducible nitric oxide synthase expression in human kidney epithelial cells.
abstract: The purpose of this study was to elucidate the signalling pathways involved in the cytokine-activated inducible nitric oxide synthase (iNOS) response in a human kidney epithelial cell line, A498. Unstimulated cells did not express iNOS. Exposure of A498 cells to a cytokine mixture consisting of interferon gamma, interleukin-1 beta and tumor necrosis factor-alpha (TNF-alpha) increased nitrite production, iNOS mRNA and protein expression. Pharmacological inhibition of tyrosine kinases, including janus kinase (JAK2), and protein kinase C (PKC) inhibited cytokine-mediated nitrite production and iNOS protein expression. The involvement of mitogen-activated protein kinases (MAPKs) was investigated. Inhibition of p38 MAPK, but not of an upstream activator of extracellular signal-regulated kinase (ERK), caused a decrease in iNOS expression and nitrite production in response to cytokines. Electrophoretic mobility shift assay of nuclear extract from cytokine-stimulated cells demonstrated a pronounced binding to a nuclear factor kappa B (NF-kappa B) sequence present in the human iNOS promoter. Furthermore, the NF-kappa B inhibitor pyrrolidinedithiocarbamate (PDTC) decreased cytokine-activated iNOS protein expression and nitrite production. The present study has demonstrated that cytokine-stimulated iNOS expression in human kidney epithelial cells involves activation of tyrosine kinases, including JAK2, PKC, p38 MAPK and NF-kappa B.
authors.affiliation: Department of Clinical Pharmacology, Lund University Hospital, Lund, Sweden.
authors.forename: Mirjana
authors.initials: M
authors.lastname: Poljakovic
authors.forename: Jens M
authors.initials: JM
authors.lastname: Nygren
authors.forename: Katarina
authors.initials: K
authors.lastname: Persson
mesh_terms: D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: D004791:Enzyme Inhibitors; D009573:Nitrites; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II