title: Role of interferon regulatory factor-1 and mitogen-activated protein kinase pathways in the induction of nitric oxide synthase-2 in retinal pigmented epithelial cells.
abstract: Bovine retinal pigmented epithelial cells express an inducible nitric oxide synthase (NOS-2) after activation with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS). Experiments were performed to investigate the involvement of interferon regulatory factor-1 (IRF-1) on NOS-2 induction and its regulation by NOS-2 inhibitors such as pyrrolidine dithiocarbamate (PDTC), an antioxidant, or protein kinase inhibitors. Analysis by transitory transfections showed that LPS, alone or with IFN-gamma, stimulated activity of the murine NOS-2 promoter fragment linked upstream of luciferase and its suppression by PDTC and by the different protein kinase inhibitors, genistein (tyrosine kinase inhibitor), PD98059 (mitogen-actived protein (MAP) kinase kinase inhibitor), and SB 203580 (p38 MAP inhibitor). Using specific antibodies, we have confirmed that extracellular signal-regulated kinases and p38 MAP kinase were activated by LPS and IFN-gamma in retinal pigmented epithelial cells. Analysis by reverse transcriptase-polymerase chain reaction, Western blot, and electrophoretic mobility shift assay demonstrated that IFN-gamma alone or combined with LPS induced an accumulation of IRF-1 mRNA and protein and IRF-1 DNA binding. Transfections assays with the IRF-1 promoter showed an induction of this promoter with IFN-gamma, potentiated by LPS. The decrease of LPS/IFN-gamma-induced IRF-1 promoter activity, IRF-1 synthesis, and IRF-1 activation, by PDTC, genistein, PD98059, and SB 203580, could explained in part the inhibition of the NOS-2 induction by these compounds. Our results demonstrate that IRF-1 is necessary for NOS-2 induction by LPS and IFN-gamma and that its synthesis requires the involvement of a redox-sensitive step, the activation of tyrosine kinases, and extracellular signal-regulated kinases 1/2 and p38 MAP kinases.
authors.affiliation: Développement, Vieillissement et Pathologie de la Rétine, U450, INSERM, Paris 75016, France.
authors.forename: V
authors.initials: V
authors.lastname: Faure
authors.forename: C
authors.initials: C
authors.lastname: Hecquet
authors.forename: Y
authors.initials: Y
authors.lastname: Courtois
authors.forename: O
authors.initials: O
authors.lastname: Goureau
mesh_terms: D000818:Animals; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004789:Enzyme Activation; D004790:Enzyme Induction; D005786:Gene Expression Regulation; D019833:Genistein / Q000378:metabolism; D050856:Interferon Regulatory Factor-1; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008156:Luciferases / Q000235:genetics; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D010750:Phosphoproteins / Q000235:genetics / Q000502:physiology*; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000201:enzymology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism