title: Differential effects of LY294002 and wortmannin on inducible nitric oxide synthase expression in glomerular mesangial cells.
abstract: Nitric oxide (NO) that is produced by inducible nitric oxide synthase (iNOS) is associated with the pathophysiology of glomerulonephritis. Numerous studies have focused on the regulation of NO production by iNOS to reduce NO-mediated cytotoxicity. In the present study, we demonstrated the differential effects of two phosphatidylinositol 3-kinase (PI3K) inhibitors, LY294002 and wortmannin, on lipopolysaccharide- (LPS) and interferon (IFN)-γ-induced NO production in a glomerular mesangial cell line, MES-13 cells. At dosages without affecting cell viability of MES-13 cells, 5μM LY294002 showed a more-significant inhibitory effect on LPS/IFN-γ-induced NO production, and iNOS protein and gene expressions than did 1μM wortmannin. Akt phosphorylation in MES-13 cells declined upon the addition of wortmannin, but not upon treatment with LY294002. Suppression of PI3K expression by small interfering (si)RNA exhibited no effect on LPS/IFN-γ-stimulated NO production or iNOS protein expression in MES-13 cells. Neither LY294002 nor wortmannin reduced IFN-γ-induced STAT-1α phosphorylation. LY294002 exhibited a more-significant inhibitory effect on NF-κB luciferase activities than wortmannin in LPS/IFN-γ-stimulated MES-13 cells. Moreover, LY294002, but not wortmannin, accelerated iNOS protein degradation and reduced the iNOS dimer/monomer ratio in MES-13 cells. Although both LY294002 and wortmannin are known as PI3K inhibitors, their differential effects on iNOS expression in MES-13 cells indicate that the effects of LY294002 on inhibiting NF-κB activation and accelerating iNOS protein degradation are through a mechanism independent of PI3K.
authors.affiliation: Department of Internal Medicine, China Medical University Beigang Hospital, 123 Sinde Road, Beigang Township, Yunlin County 65152, Taiwan, ROC.
authors.forename: Kuen-Daw
authors.initials: KD
authors.lastname: Tsai
authors.forename: Wen-Wei
authors.initials: WW
authors.lastname: Chang
authors.forename: Chia-Ching
authors.initials: CC
authors.lastname: Lin
authors.forename: Shu-Ching
authors.initials: SC
authors.lastname: Hsu
authors.forename: Yi-Ju
authors.initials: YJ
authors.lastname: Lee
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Jia-Ching
authors.initials: JC
authors.lastname: Shieh
authors.forename: Ting-Hui
authors.initials: TH
authors.lastname: Lin
mesh_terms: D000730:Androstadienes / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology*; D004396:Coloring Agents; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D050832:Interferon-Stimulated Gene Factor 3 / Q000096:biosynthesis / Q000235:genetics; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000633:toxicity; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000633:toxicity; D050527:Mesangial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D009025:Morpholines / Q000494:pharmacology*; D016328:NF-kappa B / Q000096:biosynthesis / Q000235:genetics; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis*; D051058:Oncogene Protein v-akt / Q000096:biosynthesis / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013778:Tetrazolium Salts; D013844:Thiazoles; D014162:Transfection; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D002867:Chromones; D004396:Coloring Agents; D004791:Enzyme Inhibitors; D050832:Interferon-Stimulated Gene Factor 3; D008070:Lipopolysaccharides; D009025:Morpholines; D016328:NF-kappa B; D034741:RNA, Small Interfering; D013778:Tetrazolium Salts; D013844:Thiazoles; C079868:gamma interferon activation factor; D009569:Nitric Oxide; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II; D019869:Phosphatidylinositol 3-Kinases; D051058:Oncogene Protein v-akt; C022616:thiazolyl blue; D000077191:Wortmannin