title: Induction of nitric oxide synthase in RAW 264.7 macrophages by lipoteichoic acid from Staphylococcus aureus: involvement of protein kinase C- and nuclear factor-kB-dependent mechanisms.
abstract: This study investigates the signaling pathway involved in inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) release caused by Staphylococcus aureus lipoteichoic acid (LTA) in RAW 264.7 macrophages. A phosphatidylcholine-phospholipase C (PC-PLC) inhibitor (D-609) and a phosphatidylinositol-phospholipase C (PI-PLC) inhibitor (U-73122) attenuated LTA-induced iNOS expression and NO release. Two PKC inhibitors (Go 6976 and Ro 31-8220), an NF-kappaB inhibitor (pyrrolidine dithiocarbamate; PDTC), and long-term (24 h) 12-phorbol-13-myristate acetate (PMA) treatment each also inhibited LTA-induced iNOS expression and NO release. Treatment of cells with LTA caused an increase in PKC activity; this stimulatory effect was inhibited by D-609, U-73122, or Ro 31-8220. Stimulation of cells with LTA caused IkappaB-alpha phosphorylation and IkappaB-alpha degradation in the cytosol, and translocation of p65 and p50 NF-kappaB from the cytosol to the nucleus. Treatment of cells with LTA caused NF-kappaB activation by detecting the formation of NF-kappaB-specific DNA-protein complexes in the nucleus; this effect was inhibited by Go 6976, Ro 31-8220, long-term PMA treatment, PDTC, L-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK), and calpain inhibitor I. These results suggest that LTA might activate PC-PLC and PI-PLC to induce PKC activation, which in turn initiates NF-kappaB activation, and finally induces iNOS expression and NO release in RAW 264.7 macrophages.
authors.affiliation: Graduate Institute of Biomedical Technology, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chen-Tzu
authors.initials: CT
authors.lastname: Kuo
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Chiang
authors.forename: Chun-Nin
authors.initials: CN
authors.lastname: Lee
authors.forename: Ming-Chih
authors.initials: MC
authors.lastname: Yu
authors.forename: Kuan-Jen
authors.initials: KJ
authors.lastname: Bai
authors.forename: Horng-Mo
authors.initials: HM
authors.lastname: Lee
authors.forename: Wen-Sen
authors.initials: WS
authors.lastname: Lee
authors.forename: Joen-Rong
authors.initials: JR
authors.lastname: Sheu
authors.forename: Chien-Huang
authors.initials: CH
authors.lastname: Lin
mesh_terms: D000818:Animals; D002460:Cell Line; D004790:Enzyme Induction / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000201:enzymology* / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction; D013211:Staphylococcus aureus; D013682:Teichoic Acids / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D013682:Teichoic Acids; D009569:Nitric Oxide; C009900:lipoteichoic acid; D019001:Nitric Oxide Synthase; D011493:Protein Kinase C; D010738:Type C Phospholipases