Gene/Protein Disease Symptom Drug Enzyme Compound
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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.
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PMID:Differential expression of iNOS and cNOS mRNA in human vascular smooth muscle cells and endothelial cells under normal and inflammatory conditions. 750 76

Autoimmune diabetes is characterized by an early infiltration of lymphocytes into and around islets, which is followed by selective destruction of the insulin-secreting beta-cell. Cytokines released during this inflammatory reaction have been implicated as effector molecules which mediate beta-cell destruction. In vitro treatment of rat islets with the cytokine IL-1 beta results in an inhibition of glucose-stimulated insulin secretion that is mediated by the overproduction of nitric oxide. IL-1 beta also stimulates the production of the cyclooxygenase (COX) product prostaglandin E2 (PGE2). In this study we have examined the effects of IL-1 beta on both inducible nitric oxide synthase (iNOS) and inducible cyclooxygenase (iCOX) expression, and the direct effects of nitric oxide on the activity of COX. Treatment of rat islets with 5 units/mL IL-1 beta induces a similar time-dependent production of both nitrite and PGE2. IL-1 beta-induced nitrite and PGE2 production is attenuated by the NOS inhibitor NG-monomethyl-L-arginine (NMMA), but NMMA has no inhibitory effect on the expression of either iCOX or iNOS as determined by immunoprecipitation. Actinomycin D prevents IL-1 beta-induced iCOX and iNOS expression and the production of both nitrite and PGE2 by islets, suggesting that mRNA transcription is required for IL-1 beta-induced expression of both iNOS and iCOX. The effects of exogenous arachidonic acid on both constitutive COX (cCOX) and iCOX activity were also investigated.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:IL-1 beta induces the coexpression of both nitric oxide synthase and cyclooxygenase by islets of Langerhans: activation of cyclooxygenase by nitric oxide. 750 13

The expression of nitric oxide synthase (NOS; EC 1.14.13.39) is induced in rat glomerular mesangial cells by exposure to the inflammatory cytokine interleukin 1 beta (IL-1 beta) or cAMP-elevating agents. Stimulation with IL-1 beta alone leads to an approximately 40-fold increase in NOS activity and nitrite synthesis, whereas the elevation of cAMP with forskolin, cholera toxin, salbutamol, or dibutyryl-cAMP for 24 h resulted in a 2- to 12-fold increase in NOS activity. Moreover, the combinations of IL-1 beta with each of the cAMP-elevating agents greatly enhanced NOS activity in a synergistic fashion. Northern-blot analysis demonstrated a single band of approximately 4.5 kb for the NOS mRNA in rat mesangial cells. IL-1 beta increased NOS mRNA levels in a dose- and time-dependent fashion with a peak of NOS mRNA at 24 h. Dibutyryl-cAMP also increased NOS mRNA levels in mesangial cells in a dose- and time-dependent manner. Furthermore, combination of IL-1 beta and forskolin revealed a strong synergy with maximal mRNA levels 12 h after stimulation. Nuclear run-on transcription experiments suggest that IL-1 beta and cAMP synergistically interact to increase NOS gene expression at the transcriptional level. Furthermore, message stability studies established that NOS mRNA induced by cAMP has a longer half-life than the IL-1 beta-induced message. Moreover, cAMP exposure markedly prolonged the half-life of NOS mRNA from 1 h to 3 h. These data suggest that the level of NOS mRNA is controlled by at least two different signaling pathways, one involving cAMP and the other being triggered by cytokines such as IL-1 beta. The two pathways act synergistically and thus potently up-regulate the expression of inducible NOS in rat mesangial cells.
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PMID:Two distinct signaling pathways trigger the expression of inducible nitric oxide synthase in rat renal mesangial cells. 751 1

1. Interleukin-1 beta (IL-1 beta) is a potent stimulant of inducible nitric oxide synthase (iNOS) mRNA and nitric oxide (NO) production in vascular smooth muscle (VSM) cells in culture. These studies investigate the role of adenosine 3':5'-cyclic monophosphate (cyclic AMP) in this process. 2. Dibutyryl cyclic AMP (db cyclic AMP, 0.1-1 mM), forskolin (1-10 microM) and the phosphodiesterase inhibitor, Ro 20-1724 (1-10 microM), all of which increase intracellular cyclic AMP, had no effect on NO production when added alone but markedly enhanced NO production by IL-1 beta-stimulated VSM cells in a dose-dependent manner. Consistent with a cyclic AMP-mediated action, isoprenaline (1-10 microM) increased NO production from IL-1 beta-stimulated cells. Dibutyryl cyclic GMP (db cyclic GMP) had no effect at concentrations up to 1 mM. 3. Pursuing these observations, iNOS protein levels were examined by Western blot analysis and iNOS mRNA levels were measured by reverse transcription and amplification of the resultant cDNA using the polymerase chain reaction. In addition to enhancing NO production, db cyclic AMP increased iNOS protein and mRNA above that produced by IL-1 beta alone. 4. These data demonstrate a major effect of cyclic AMP on cytokine-induced NOS activity in VSM cells, mediated at least in part by regulating synthesis of iNOS, and has implications for the pathogenesis and management of septic shock.
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PMID:Induction of nitric oxide synthase in cultured vascular smooth muscle cells: the role of cyclic AMP. 752 Dec 56

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.
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PMID:Inducible nitric oxide synthase from human articular chondrocytes: cDNA cloning and analysis of mRNA expression. 752 54

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.
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PMID:Nitric oxide production by human proximal tubular cells: a novel immunomodulatory mechanism? 753 48

Unlike large-vessel endothelial cells in cell culture, cardiac microvascular endothelial cells (CMEC) isolated from adult rat ventricular muscle exhibit little detectable constitutive nitric oxide (NO) synthase activity after isolation in vitro but respond to specific combinations of inflammatory mediators with an increase in inducible NO synthase (iNOS; type 2 NO synthase) activity. CMEC iNOS is induced by soluble inflammatory mediators in lipopolysaccharide-activated rat alveolar macrophage-conditioned medium at 24 hours, and this induction can be partially prevented by either interleukin-1 (IL-1) receptor antagonist or a polyclonal anti-rat tumor necrosis factor-alpha (TNF-alpha) antiserum. Interferon-gamma (IFN-gamma), which by itself does not induce iNOS in CMEC, potentiates and accelerates iNOS induction by IL-1 beta. Transforming growth factor-beta (TGF-beta) decreases iNOS activity, protein content, and mRNA abundance in IL-1 beta- and IFN-gamma-pretreated CMEC. To determine whether NO released by CMEC would affect myocyte contractile function in vitro, freshly isolated ARVM were allowed to settle onto confluent, serum-starved CMEC that had been pretreated for 24 hours with IL-1 beta, a cytokine that alone does not affect myocyte contractile function in vitro. Baseline contractile amplitude, at 2 Hz and 37 degrees C, of myocytes in heterotypic culture with IL-1 beta-pretreated CMEC was not different from that of myocytes in control, homotypic myocyte cultures. However, cocultured myocytes exhibited decreased contractile responsiveness to 2 nmol/L isoproterenol compared with control cells, and this could be reversed by the addition of 1 mmol/L NG-monomethyl-L-arginine, an inhibitor of NOS.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Contractile responsiveness of ventricular myocytes to isoproterenol is regulated by induction of nitric oxide synthase activity in cardiac microvascular endothelial cells in heterotypic primary culture. 754 25

Recent evidence suggests that the production of nitric oxide (NO) may have important roles in the regulation of osteoblast and osteoclast metabolism. The present study was performed to investigate the effects of interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) on the expression of inducible NO-synthase (iNOS) and to measure high-output production of NO by primary rat osteoblasts and osteoblastic cell lines ROS 17/2.8, MC3T3-E1 and MG-63. In addition, we have investigated if NO may mediate some of the effects of these cytokines on osteoblast metabolism. Northern blots and immunocytochemistry revealed time-dependent iNOS messenger RNA and protein expression in primary rat osteoblasts in response to cytokine treatment. Reverse transcription polymerase chain reaction amplified an 807-base pair (bp) product from ROS 17/2.8 cells, which had a size and restriction enzyme-cut pattern identical to that predicted for authentic rat iNOS. Nitrite accumulation in culture medium was induced by IFN-gamma in a time- and dose-dependent manner and inhibited by cotreatment with inhibitors of NOS activity and by dexamethasone. IL-1 beta, TNF-alpha, and bacterial lipopolysaccharide were found to have weak stimulatory effects on nitrite production on their own. However, IL-1 beta and TNF-alpha showed strong synergy with IFN-gamma, but, surprisingly, lipopolysaccharide was found to exert potent inhibitory effects on IFN-gamma-induced nitrite synthesis. Basal production of nitrite and induction of its synthesis was similarly observed with primary rat osteoblasts as well as ROS 17/2.8, MC3T3-E1, and MG-63 cell lines. Cytokine-induced NO production significantly reduced osteoblast activity, as was evidenced by inhibition of DNA synthesis, cell proliferation, alkaline phosphatase activity, and osteocalcin production. The results provide evidence for a basal expression of iNOS activity and show that the iNOS messenger RNA, protein, and enzyme activity are all induced by cytokines across the species. The data further suggest that osteoblast-derived NO may have an important role in mediation of localized bone destruction associated with inflammatory bone diseases such as rheumatoid arthritis.
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PMID:Cytokine-stimulated expression of inducible nitric oxide synthase by mouse, rat, and human osteoblast-like cells and its functional role in osteoblast metabolic activity. 758 94

Experimental autoimmune encephalomyelitis (EAE) is a T cell-mediated inflammatory demyelinating disorder of the central nervous system (CNS) which serves as a prime animal model for the human disease multiple sclerosis. Previous studies from these laboratories demonstrated excess nitric oxide (NO) in the CNS of EAE-affected mice, and amelioration of EAE with a selective inhibitor of the inducible nitric oxide synthase (iNOS). Recent studies from other laboratories have indicated that prostaglandin PGE2 is increased in CNS tissues of EAE-affected rodents and that EAE is prevented by the inhibition of cyclooxygenase activity. The present study investigated the ability of encephalitogenic lymphoid cells to induce NOS and cyclooxygenase (COX-2) in the murine macrophage line, RAW 264.7. In order to mimic the extracellular milieu present in EAE lesions, conditioned medium (CM) of activated EAE-inducer cells was added to this macrophage line. CM caused a time-dependent increase in nitrite, indicating NO production. Reverse-transcriptase PCR demonstrated iNOS mRNA in RAW 264.7 cells, first detected at 3 h, and Western blots confirmed the induction in RAW cells of the 130-kDa iNOS protein. Production of nitrite by CM-exposed RAW 264.7 cells was blocked by inhibitors of NOS (L-N-methylarginine or aminoguanidine) or by antibodies to murine IFN-gamma or IL-1 beta. CM of activated encephalitogenic cells induced production of PGE2 by RAW 264.7 cells, as determined by ELISA, and Western blots identified the presence of the 70-80-kDa inducible COX (COX-2) protein. Induction of COX-2 could be inhibited by antibody to IFN-gamma. Thus, encephalitogenic cells are capable of inducing the expression of the inflammatory enzymes iNOS and COX-2 in a murine macrophage line via the T cell cytokine IFN-gamma, alone or in combination with IL-1 beta.
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PMID:Mediation of inflammation by encephalitogenic cells: interferon gamma induction of nitric oxide synthase and cyclooxygenase 2. 759 55

Nitric oxide (NO) synthase (NOS), the enzyme responsible for NO formation, is found in hypothalamic neurons containing oxytocin (OT), vasopressin (VP), and to a lesser extent corticotropin-releasing factor (CRF). Because NO is reported to modulate endocrine activity, we have investigated the hypothesis that endogenous NO participates in ACTH released by various secretagogues in the rat. In the adult male rat, the intravenous injection of interleukin-1 beta (IL-1 beta; 0.2-0.3 micrograms/kg), VP (0.3-0.9 micrograms/kg), and OT (30 micrograms/kg) significantly increased plasma ACTH and corticosterone levels. Pretreatment with the L-form, but not the D-form, of N omega nitro-L-arginine-methylester (L-NAME; a specific inhibitor of NOS) markedly augmented the effects of these secretagogues whether it was injected acutely or over a 4 d period. Blockade of NOS activity also caused significant (P < 0.01) extensions of the duration of action of IL-1 beta, VP, and OT. In contrast, L-NAME did not significantly alter the stimulatory action of peripherally injected CRF, or centrally administered IL-1 beta. Administration of L-arginine, but not D-arginine (100 mg/kg), used as a substrate for basal NO synthesis and which did not by itself alter the activity of the hypothalamic-pituitary-adrenal (HPA) axis, blunted IL-1-induced ACTH secretion, and reversed the interaction between L-NAME and IL-1 beta. The stimulatory action of endotoxin, a lipopolysaccharide that releases endogenous cytokines, was also augmented by inhibition of NO formation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:In the rat, endogenous nitric oxide modulates the response of the hypothalamic-pituitary-adrenal axis to interleukin-1 beta, vasopressin, and oxytocin. 815 53


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