Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:1.5.1.19 (NOS)
7,285 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To examine the potential contribution of endothelial cell cNOS (ec-cNOS) and inducible NOS (iNOS) in controlling vascular tone under normal versus inflammatory conditions, we performed Northern hybridizations to examine the differential expression of each NOS mRNA in human aortic endothelial cells (AOEC) and human aortic smooth muscle cells (AOSMC) cultured for 8 h in the presence or absence of cytokines (IL-1 beta, TNF-alpha, and IFN-gamma) and LPS. Cytokine/LPS treatment induced a 4.4 kb iNOS mRNA in the human AOSMC; in contrast, cytokine/LPS treatment down regulated the expression of ec-cNOS mRNA in the AOEC. No iNOS mRNA was detected in the AOEC under the conditions examined. These results suggest that under specific inflammatory conditions the generation of NO in vascular tissue switches from ec-cNOS in the endothelium to iNOS in the smooth muscle.
...
PMID:Differential expression of iNOS and cNOS mRNA in human vascular smooth muscle cells and endothelial cells under normal and inflammatory conditions. 750 76

Production of nitric oxide (NO) by macrophages is enhanced upon activation by bacterial endotoxins and cytokines mainly via an increase of the intracellular content of the inducible isoform of nitric oxide synthase (i-NOS). We have studied in detail the effect of several modulators of macrophage activity on steady state levels of i-NOS mRNA in the mouse macrophage-like cell line RAW 264.7. Bacterial lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) were found to be effective inducers of i-NOS mRNA, in accordance with their known ability to stimulate both i-NOS activity and NO production in macrophages from different sources, while TNF-alpha, IL-1, or IL-6 was ineffective in this regard. Accumulation of i-NOS mRNA in response to either LPS or IFN-gamma stimulation was accompanied by increased i-NOS gene transcription, as detected both by using a nuclear "run-on" transcription assay and by transient transfection of the cloned gene promoter in RAW 264.7 cells. Co-stimulation of the cells with both inducers resulted in higher steady state levels of i-NOS mRNA in the absence, however, of a corresponding potentiation of the rate of gene transcription. This was due primarily to a considerable effect of LPS on i-NOS mRNA stability, with prolongation of its half-life from 1-1.5 h, in the presence of IFN-gamma alone, to 4-6 h in the presence of both LPS and IFN-gamma.
...
PMID:Dual mechanism for the control of inducible-type NO synthase gene expression in macrophages during activation by interferon-gamma and bacterial lipopolysaccharide. Transcriptional and post-transcriptional regulation. 751 Jun 85

Human articular chondrocytes can be induced by IL-1 beta, TNF-alpha or LPS to release high levels of nitric oxide. Using degenerate PCR primers based on homologous regions from previously cloned NOS enzymes, a 1.9 kb cDNA fragment was amplified from IL-1 beta stimulated but not from resting chondrocytes. Screening of a lambda gt11 cDNA library, which was prepared from RNA of IL-1 beta activated chondrocytes, resulted in the isolation of the complete cDNA, encoding a protein of 1153 amino acids. Comparison of the cDNA sequence identified human chondrocyte iNOS to be almost identical to the sequence recently reported for the hepatocyte enzyme, differing in 12 amino acids. Northern blot analysis revealed, that stimulated chondrocytes express a single 4.5 kb iNOS mRNA species. IL-1 beta induction of iNOS mRNA was detectable by 6 h and continued to be elevated throughout a 72 h culture period. Screening of a human bone cDNA library identified this inducible NOS to be also expressed by bone cells.
...
PMID:Inducible nitric oxide synthase from human articular chondrocytes: cDNA cloning and analysis of mRNA expression. 752 54

To investigate how the number of mast cells is controlled, we studied a murine mastocytoma cell line. Based on electron microscopic observation of nuclear condensation and electrophoretic evidence with DNA fragmentation, these mastocytoma wells were shown to undergo apoptosis. This apoptosis was dependent on the concentrations of serum and L-arginine and was enhanced by TNF-alpha. We confirmed that apoptosis was mediated by nitric oxide (NO) synthase; inducible NO synthase (iNOS) mRNA was strongly expressed in apoptotic cells, while an inhibitor of NOS, NG-monomethyl-L-arginine, and dexamethasone prevented apoptosis in addition to inhibiting iNOS mRNA expression. Our results suggest that iNOS expression is very important in regulating the proliferation of mast cells under pathological conditions.
...
PMID:Nitric oxide-mediated apoptosis in murine mastocytoma. 752 98

It is believed that human proximal tubular cells may possess immunological function and play an important role in a variety of renal disease states such as interstitial nephritis, allograft rejection and drug induced nephrotoxicity. The role of cytokines and nitric oxide in the human forms of these disease states is not clear. In this study we examined the effect of stimulation with the cytokines IL-1 beta. TNF-alpha and IFN-gamma, individually and in combination, upon primary cultures of human proximal tubular cells. Nitric oxide production increased significantly within 24 hours following cytokine stimulation. This response was inhibited, in a dose dependent manner, by L-NMMA. PCR amplification of mRNA extracted from control and cytokine stimulated human proximal tubular cells revealed a NOS product with a > 97% homology with human hepatocyte inducible nitric oxide synthase. The results of this study clearly show that human proximal tubular cells, in primary culture, are capable of producing nitric oxide in response to an immune challenge secondary to the induction of nitric oxide synthase.
...
PMID:Nitric oxide production by human proximal tubular cells: a novel immunomodulatory mechanism? 753 48

Large amount of nitric oxide (NO) are produced at sites of inflammation through the action of inducible nitric oxide synthase (iNOS) present in both infiltrating leucocytes and activated, resident tissue cells. However, the role of NO in inflammation remains unclear. NO is a vasodilator, which inhibits the adhesion of neutrophils to the vascular endothelium; it reduces the production of IL-6 by Kupffer cells and chondrocytes, and the production of gamma-IFN and TNF-alpha by splenocytes. The literature provides contradictory information on the effect of NO on vascular leakiness, chemotaxis, prostaglandin production and tissue damage. Increasingly, data suggest that NO is immunosuppressive. Inhibitors of NOS have potent prophylactic activity in several but not all, animal models of inflammatory disease. However, in rat adjuvant arthritis, therapeutic activity is weak. Whether inhibitors of iNOS will be therapeutically useful in human inflammatory diseases cannot be predicted on the basis of present information.
...
PMID:Nitric oxide: what role does it play in inflammation and tissue destruction? 754 Mar 50

Evidence has previously been presented for an immunomodulatory role of a soluble activity, designated as tumor-derived recognition factor (TDRF), which was produced constitutively by P815 mastocytoma, L 1210 leukemia and other murine tumor targets. TDRF synergized with IFN-gamma and IL-2 to promote TNF-alpha and mRNA synthesis and release by murine macrophages for increased autocrine induction of nitric oxide (NO)-mediated tumor cytotoxicity. We have now further assessed the modulatory role of TDRF on TNF-alpha, TNF receptors (TNF-R) and NOS mRNA synthesis. Macrophages activated by INF-gamma priming and triggering by rTNF-alpha bacterial lipopolysaccharide (LPS) of IL-2 evoked greater NO generation in the presence than in the absence of L1210 targets. TDRF-containing culture fluid from L1210 targets was subsequently confirmed to synergize with IFN-gamma and rTNF-alpha, LPS or IL-2 triggering agents to promote increased TNF-alpha mRNA for autocrine induction of NOS mRNA synthesis with resultant augmentation of NO generation. IFN-gamma selectively upregulated TNF-R1 mRNA expression, whereas either IL-2 or LPS upregulated only TNF-R2 mRNA expression. TDRF combined with IFN-gamma to further upregulate TNF-R1 mRNA and with either IL-2 or LPS to further upregulate TNF-R2, mRNA expression. These findings indicate that TDRF activity synergizes with either IL-2 or LPS triggering agents for enhanced activation of IFN-gamma-primed macrophages by promotion of TNF-alpha and TNF-R mRNA synthesis for autocrine induction of NOS with resultant increased NO-mediated tumor cytotoxicity.
...
PMID:Tumor-derived factor synergizes with IFN-gamma and LPS, IL-2 or TNF-alpha to promote macrophage synthesis of TNF-alpha and TNF receptors for autocrine induction of nitric oxide synthase and enhanced nitric oxide-mediated tumor cytotoxicity. 754 21

Nitric oxide (NO) is a radical molecule that not only serves as a vasodilator and neurotransmitter but also acts as a cytotoxic effector molecule of the immune system. The inducible enzyme making NO, inducible NO synthase (iNOS), is transcriptionally activated by IFN-gamma and TNF-alpha, cytokines which are produced during viral infection. We show that iNOS is induced in mice infected with the Coxsackie B3 virus. Macrophages expressing iNOS are identified in the hearts and spleens of infected animals with an antibody raised against iNOS. Infected mice have increased titers of virus and a higher mortality when fed NOS inhibitors. Thus, viral infection induces iNOS in vivo, and NO inhibits viral replication. NO is a novel, nonspecific immune defense against viruses in vivo.
...
PMID:Nitric oxide inhibits viral replication in murine myocarditis. 862 66

Human mesangial cells express an inducible form of nitric-oxide synthase (iNOS) after treatment with cytokines. Tetrahydrobiopterin (BH4), an essential cofactor for NOS, is required for cytokine-induced NO generation. We report here that BH4 is necessary not only for the activity but also for the expression of iNOS in human mesangial cells. Inhibition of de novo BH4 synthesis with 2,4-diamino-6-hydroxypyrimidine (DAHP) significantly attenuated iNOS activity as well as mRNA and protein expression in response to interleukin 1beta plus tumor necrosis factor alpha (IL-1beta/TNF-alpha). In contrast, sepiapterin, which provides BH4 through the pterin salvage pathway, strongly potentiated IL-1beta/TNF-alpha-induced iNOS expression and abrogated the inhibitory effect of DAHP. Inhibition of the pterin salvage pathway with methotrexate abolished sepiapterin potentiation of iNOS induction but did not alter the effect of IL-1beta/TNF-alpha. Determination of intracellular pteridines confirmed that sepiapterin markedly raised BH4 content, an effect that was blocked by methotrexate. These results suggest that BH4 availability plays an important role in the regulation of iNOS expression. The effect of BH4 appears to be mediated, at least in part, by an increase in mRNA stability, as indicated by the observation that DAHP shortened, whereas sepiapterin prolonged the half-life of IL-1beta/TNF-alpha-induced iNOS mRNA. Taken together, our results suggest that the biosynthesis of BH4 contributes to cytokine induction of iNOS expression in human mesangial cells through the stabilization of iNOS mRNA.
...
PMID:Role of tetrahydrobiopterin availability in the regulation of nitric-oxide synthase expression in human mesangial cells. 866 83

Nitric oxide (NO) is a short-lived pleiotropic mediator with a multitude of biologic functions. The inducible form of NO synthase (iNOS) is responsible for the discontinuous production of high amounts of NO and is important for the cytotoxic capacity of macrophages in rodents, whereas NO production by human macrophages or monocytes (MO) is under debate. Here we report that high amounts of NO are synthesized in cocultures of human MO with the human carcinoma cell line RT4 without further stimulation. Both cell types have to be viable and metabolically active for NO production. However, in contrast to reports by others, we could demonstrate that tumor cells and not MO are the producers of NO by the following findings: 1) NO release was induced in RT4 cells, but not in MO, by diluted supernatants (SN) of RT4/MO cocultures; 2) SN of MO stimulated with tumor cell membrane preparations were sufficient to induce NO release by tumor cells; and 3) NOS mRNA expression could be detected only in tumor cells, not in MO. Separating both cells by a cell-impermeable membrane resulted in NO amounts comparable to those in cocultures with direct cell contact, indicating one or more soluble NO-inducing factors. Considerable amounts of IL-1 beta and TNF-alpha were present in cocultures. IL-1 beta and TNF-alpha, mediators produced by activated MO, in combination induce NO release in RT4 cells. Blocking of TNF-alpha or IL-1 in SN inhibited NO release in RT4 cells. This indicates that IL-1 beta and TNF-alpha play prominent roles in iNOS induction by MO in RT4 tumor cells.
...
PMID:Human monocytes induce a carcinoma cell line to secrete high amounts of nitric oxide. 875 34


1 2 3 4 5 6 7 8 9 10 Next >>

---