Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.13.39 (NO synthase)
 15,778 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Murine macrophages express high levels of nitric oxide synthase and produce large amounts of nitric oxide (NO) when stimulated with certain cytokines in the presence of a trace amount of lipopolysaccharide (LPS). The stimulatory cytokines include interleukin-1 (IL-1), interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) and migration inhibitory factor. Activated macrophages are highly effective killers of intra- and extra-cellular pathogens. However, as excessive NO can lead to immunopathology (diabetes, graft-v.-host disease, EAE, liver cirrhosis, rheumatoid arthritis), NO production is necessarily under tight regulation. A number of cytokines, including IL-4, IL-10 and transforming growth factor-beta, can down regulate the induction of NO synthase in macrophages. In addition, macrophages exposed to LPS alone and then stimulated with a mix of IFN-gamma and LPS express significantly lower levels of NO synthase than cells stimulated without pre-exposure to LPS. Furthermore, NO can reduce the activity of NO synthase by feedback inhibition, and also inhibit the production of IFN-gamma by Th1 cells (thus turning off its own synthesis from upstream). The regulatory pathways involve tyrosine kinase and protein kinase C.
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PMID:The role of nitric oxide in parasitic diseases. 751 Jan

Several lines of evidence indicate that insulin-like growth factor-I (IGF-I) is a potent mediator of vasodilation. To elucidate the mechanism and site of action of IGF-I, we performed continuous monitoring of nitric oxide (NO) release from endothelial cells using a highly-sensitive amperometric NO-sensor. Two types of cultured cells were used: human umbilical vein endothelial cells and immortalized rat renal interlobar artery endothelial cells. In separate experiments, [Ca2+]i changes in response to IGF-I were measured spectrofluorometrically in fura-2-loaded cells. Stimulation with IGF-I resulted in a rapid, dose-dependent increase in [NO] as detected by the NO-probe positioned 1 mm above the monolayers, followed by a sustained elevation lasting for at least five minutes. The effect of IGF-I was significantly suppressed by pretreatment with anti-IGF-I antibody, suggesting that it was specific for IGF-I. NG-nitro-L-arginine methyl ester, an inhibitor of NO synthesis, significantly blunted responses to IGF-I, but dexamethasone preincubation did not reduce the IGF-I-induced release of NO. These results indicate that the observed IGF-I-induced release of NO is a result of activation of the constitutive, rather than the inducible type of NO synthase in endothelial cells. Genistein, a tyrosine kinase inhibitor, resulted in a profound suppression of the IGF-I-induced release of NO. IGF-I did not affect [Ca2+]i in either type of cells. Therefore, IGF-I-induced NO production by both types of endothelial cells is mediated via a tyrosine kinase-dependent mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Direct demonstration of insulin-like growth factor-I-induced nitric oxide production by endothelial cells. 751 35

The cytotoxic effect of lipopolysaccharide (LPS) was examined on bovine aortic endothelial cell proliferation in vitro. These LPS-induced cytotoxicity (IC50 = 20 ng/ml) was not inhibitable by substances regulating the formation of nitric oxide (NO). e.g. by NG-monomethyl-L-arginine (L-NMMA), an inhibitor of NO synthesis, and by the glucocorticoid dexamethasone, an inhibitor of the induction of NO synthase. Also other substances which inhibit the generation or action of oxygen radicals, as glutathion and the xanthine oxidase inhibitor allopurinol did not prevent the cytotoxic effect of LPS. Only tyrphostin B46, an inhibitor of tyrosine kinase, attenuated the toxic LPS effect, suggesting that the LPS-induced cytotoxicity in bovine aortic endothelial cell cultures is mediated by a specific tyrosine kinase, and not by NO or oxygen radicals.
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PMID:Investigations into the mechanism of toxicity of lipopolysaccharide (LPS) in bovine aortic endothelial cells. 756 18

Nitric oxide (NO) formation via the expression of an endotoxin- and cytokine-inducible NO synthase (iNOS) within the vascular smooth muscle is thought to be responsible for the cardiovascular collapse that occurs during septic shock and antitumor therapy with cytokines. Because the molecular mechanisms that underlie induction of iNOS are still unclear and because tyrosine kinases are implicated in interleukin-1 beta (IL-1 beta)-induced prostaglandin synthesis in mesangial cells and in NO generation by an insulinoma cell line, we investigated the influence of tyrosine kinase inhibitors on iNOS induction in cultured rat aortic smooth muscle cells (RASMC). The production of biologically active NO was demonstrated by L-arginine-dependent guanosine 3',5'-cyclic monophosphate (cGMP) accumulation after a 3-h exposure to either IL-1 beta or lipopolysaccharide (LPS). Pretreatment of RASMC for 30 min with the tyrosine kinase inhibitor genistein prevented both IL-1 beta- and LPS-elicited cGMP accumulation in a concentration-dependent manner. Geldanamycin, a chemically different tyrosine kinase inhibitor, also blocked cGMP formation in response to both LPS and IL-1 beta at nanomolar concentrations. Genistein and geldanamycin inhibited cGMP accumulation even when added 90 min after LPS exposure, but no inhibition was observed when they were included at later time points (120-180 min), suggesting that the inhibitors had no direct effect on iNOS activity after its induction. Formation of cGMP in response to sodium nitroprusside and to NO released from bovine aortic endothelial cells remained virtually unaffected by genistein and geldanamycin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Tyrosine kinase inhibitors suppress endotoxin- and IL-1 beta-induced NO synthesis in aortic smooth muscle cells. 821 7

In this study, we demonstrate that glycosylphosphatidylinositol (GPI) is a major toxin of Plasmodium falciparum origin responsible for nitric oxide (NO) production in host cells. Purified malarial GPI is sufficient to induce NO release in a time- and dose-dependent manner in macrophages and vascular endothelial cells, and regulates inducible NO synthase expression in macrophages. GPI-induced NO production was blocked by the NO synthase-specific inhibitor L-N-monomethylarginine. GPI also synergizes with IFN-gamma in regulating NO production. The structurally related molecules dipalmitoylphosphatidylinositol and iM4 glycoinositolphospholipid from Leishmania mexicana had no such activity, and the latter antagonized IFN-gamma-induced NO output. GPI activates macrophages by initiating an early onset tyrosine kinase-mediated signaling process, similar to that induced by total parasite extracts. The tyrosine kinase antagonists tyrphostin and genistein inhibited the release of NO by parasite extracts and by GPI, alone or in combination with IFN-gamma, demonstrating the involvement of one or more tyrosine kinases in the signaling cascade. GPI-induced NO release was also blocked by the protein kinase C inhibitor calphostin C, demonstrating a role for protein kinase C in GPI-mediated cell signaling, and by pyrrolidine dithiocarbamate, indicating the involvement of the NF-kappa B/c-rel family of transcription factors in cell activation. A neutralizing mAb to malarial GPI inhibited NO production induced by GPI and total malarial parasite extracts in human vascular endothelial cells and murine macrophages, indicating that GPI is a necessary agent of parasite origin in parasite-induced NO output. Thus, in contrast to dipalmitoylphosphatidylinositol and glycoinositolphospholipids of Leishmania, malarial GPI initiates a protein tyrosine kinase- and protein kinase C-mediated signal transduction pathway, regulating inducible NO synthase expression with the participation of NF-kappa B/c-rel, which leads to macrophage and vascular endothelial cell activation and downstream production of NO. These events may play a role in the etiology of severe malaria.
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PMID:Glycosylphosphatidylinositol toxin of Plasmodium induces nitric oxide synthase expression in macrophages and vascular endothelial cells by a protein tyrosine kinase-dependent and protein kinase C-dependent signaling pathway. 859 42

Recent evidence indicates that nitric oxide (NO) produced after expression of inducible NO synthase (iNOS) mediates cytokine-induced inhibition of insulin secretion by pancreatic islets. The current studies were designed to characterize the involvement of immediate-early response genes, c-fos and c-jun, in interleukin 1 (IL-1)-induced expression of iNOS. iNOS messenger RNA (mRNA) expression by both rat islets and RINm5F cells was time dependent, with maximal expression observed after an approximately 3- to 6-h exposure to IL-1. IL-1 also stimulated rapid and transient expression of c-fos and c-jun by both rat islets and RINm5F cells, with maximal mRNA accumulation detected 30-60 min after IL-1 treatment. IL-1-induced protein synthesis of Fos and Jun was observed as early as 30 min, peaked between 3-5 h, and decreased by 8 h after IL-1 treatment. Temporal correlation of Fos and Jun expression and iNOS gene induction suggested that Fos and Jun might regulate iNOS gene transcription by rodent pancreatic beta-cells. The present study, however, indicates that IL-1 induced expression of Fos and Jun does not seem to participate in the regulation of iNOS and mRNA expression, because: 1) cycloheximide (1 microM) completely inhibited Fos expression but had no inhibitory effect on iNOS mRNA levels; and 2) tyrosine kinase inhibitors genistein and herbimycin A completely inhibited IL-1 induced iNOS expression but did not block c-fos and c-jun expression. These results indicate that two separate signaling pathways may exist for induction of c-fos and c- jun and iNOS genes and that de novo synthesis of Fos and Jun does not participate in the regulation of iNOS gene expression.
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PMID:Interleukin 1-induced Fos and Jun do not regulate inducible nitric oxide synthase in rat islets of Langerhans and RINm5F cells. 860 91

Cytokines and endotoxin stimulate inducible NO synthase (iNOS) in different types of cells; however, little is known about regulatory mechanisms. Using the Griess reagent for nitric levels, Western blots for iNOS protein, Northern blots for iNOS mRNA, and transient transfection studies to monitor transcription, we determined potential mechanisms involved in interleukin-1beta stimulation of iNOS in cultured neonatal ventricular myocytes. When myocytes were treated with interleukin-1beta (5 ng/mL), nitrite levels increased, and this effect was inhibited 80% by the specific iNOS inhibitor aminoguanidine. Neither interferon gamma nor tumor necrosis factor-alpha alone stimulated nitrite production. Bacterial endotoxin alone stimulated nitrites and potentiated the effect of interleukin. To determine whether a tyrosine kinase-mediated signaling pathway was involved in interleukin action, we used the inhibitor genistein, which blocked interleukin-stimulated nitrites, iNOS protein, and iNOS mRNA. To determine the effect of activation of protein kinase C, we treated cells with the phorbol ester phorbol 12-myristate 13-acetate (PMA). PMA decreased both interleukin-stimulated nitrites and iNOS protein by 40%. To determine the involvement of cyclic nucleotides, cells were treated with either dibutyryl cAMP or cGMP. cAMP (1 mmol/L) stimulated iNOS mRNA, protein, and nitrite production, whereas cGMP had no effect. To test for a direct effect of interleukin on transcription of the iNOS gene, we transfected the full-length mouse iNOS 5' regulatory sequences (-1592 to +160) coupled to a luciferase reporter gene (-1592iNOSLuc). Interleukin stimulated luciferase activity 1.8 +/- 0.2-fold. To determine whether interleukin also affects iNOS mRNA stability, interleukin-stimulated iNOS mRNA was allowed to decay in the presence of the transcription inhibitor actinomycin D. iNOS mRNA t1/2 (approximately 1 hour) was not affected by interleukin. Thus, our data suggest that (1) interleukin-1beta is the primary cytokine in myocyte iNOS regulation and acts predominantly at the transcriptional level; (2) interleukin stimulation of iNOS mRNA and protein is coupled to a tyrosine kinase-mediated signaling pathway; and (3) protein kinase C and cAMP can modify interleukin signaling by decreasing and increasing iNOS, respectively.
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PMID:Mechanisms of interleukin-1beta regulation of nitric oxide synthase in cardiac myocytes. 861 29

Signalling pathways determining the shear stress-induced production of NO from endothelial cells in situ were investigated using a bioassay system in which shear stress was increased by inducing vasoconstriction in an endothelium-intact donor segment (rabbit iliac artery) while maintaining a constant luminal perfusion rate. Shear stress-induced NO production, as assessed by changes in the tone of a preconstricted endothelium-denuded detector ring, was biphasic and consisted of an initial transient (20- to 25-minute) Ca(2+)-dependent phase followed by a Ca(2+)-independent plateau phase, which was maintained as long as the donor segment remained constricted. Stretching the donor segments to their in vivo length abolished the initial phase without affecting the plateau phase of NO release. Inhibition of the Na(+)-H+ exchanger using HOE 694 elicited an intracellular acidification which attenuated shear stress-induced NO production. The specific protein kinase C inhibitor, Ro 31-8220, was without effect, whereas the unspecific inhibitors, staurosporine and calphostin C, abolished the shear stress-induced production of NO. Erbstatin A, a tyrosine kinase inhibitor, attenuated the shear stress-induced tyrosine phosphorylation of specific cellular proteins and abrogated the associated NO production. In summary, these data indicate that shear stress activates the NO synthase at basal levels of [Ca2+]i via a mechanotransduction cascade that involves tyrosine phosphorylation and can be modulated by changes in pHi. The apparent fundamental alteration of the endothelial NO synthase under shear stress that renders its maintained activation independent of an increase in [Ca2+]i is probably the consequence of a change in the enzyme microenvironment.
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PMID:Intracellular pH and tyrosine phosphorylation but not calcium determine shear stress-induced nitric oxide production in native endothelial cells. 862 Jun 15

The pathogenesis of viral myocarditis involves contributions from the virus, the immune system and myocytes. In defining the molecular contributions in the disease process, modulations of the components of the immune system through transgenic knockout models provide useful insights. Advantages of the transgenic knockout models are that they allow biological evaluation of the importance of a particular molecule in the physiological context of an intact organism. Furthermore, the techniques of transgenic knockout models are now standardized, even though they are still technically challenging and time consuming. An example in myocarditis is the IRF-1 knockout mouse, where there is a complete absence of the inducible form of nitric oxide synthetase in the tissues. These animals are exquisitely sensitive to coxsackieviral infection, with extremely high mortality. On the other hand, CD4 knockouts appear to still have myocarditis in an autoimmune myocarditis model, while p56lck knockouts (the T-cell tyrosine kinase signalling molecule) appears to be free of viral myocarditis. These elegant systems of molecular manipu-lation should allow us unique insights into the pathogenesis of myocarditis.
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PMID:The role of transgenic knockout models in defining the pathogenesis of viral heart disease. 868 95

To clarify the induction pathway of inducible nitric oxide (NO) synthase in the brain, we examined the effects of interferon-gamma and lipopolysaccharide on the induction of inducible NO synthase in glial cells cultured from neonatal rats, compared to those in the macrophage cell line RAW264.7 which was derived from Abelson leukemia virus-induced BALB/c lymphocytic lymphoma. NO synthase activity (NO2- accumulation) and 130 kDa protein of inducible NO synthase were induced 24 h after treatment with interferon-gamma or lipopolysaccharide in both glial cells and RAW264.7 macrophages. These induction activities were inhibited by a tyrosine kinase inhibitor, herbimycin A. Immunoprecipitation assay using antibodies against Janus kinases, and the signal transducer and activator of transcription-1 (STAT1), revealed that interferon-gamma induced tyrosine phosphorylation of the just another kinase-2 (Jak2) and STAT1 alpha but did not induced the phosphorylation of Jak1, the non-receptor tyrosine kinase-2 (Tyk2) and STAT1 beta. Tyrosine phosphorylation of Jak2 and STAT1 alpha induced by interferon-gamma was also inhibited by herbimycin A, while lipopolysaccharide did not induce any tyrosine phosphorylation of Janus kinases and STAT1 at all. These results suggest that the interferon-gamma-induced inducible NO synthase induction involves activation of Jak2-STAT1 alpha pathway in both glial cells and macrophages.
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PMID:Possible involvement of Janus kinase Jak2 in interferon-gamma induction of nitric oxide synthase in rat glial cells. 881 44


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