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

Insulin stimulates production of NO in vascular endothelium via activation of phosphatidylinositol (PI) 3-kinase, Akt, and endothelial NO synthase. We hypothesized that insulin resistance may cause imbalance between endothelial vasodilators and vasoconstrictors (e.g., NO and ET-1), leading to hypertension. Twelve-week-old male spontaneously hypertensive rats (SHR) were hypertensive and insulin resistant compared with control Wistar-Kyoto (WKY) rats (systolic blood pressure 202 +/- 11 vs. 132 +/- 10 mmHg; fasting plasma insulin 5 +/- 1 vs. 0.9 +/- 0.1 ng/ml; P < 0.001). In WKY rats, insulin stimulated dose-dependent relaxation of mesenteric arteries precontracted with norepinephrine (NE) ex vivo. This depended on intact endothelium and was blocked by genistein, wortmannin, or N(omega)-nitro-l-arginine methyl ester (inhibitors of tyrosine kinase, PI3-kinase, and NO synthases, respectively). Vasodilation in response to insulin (but not ACh) was impaired by 20% in SHR (vs. WKY, P < 0.005). Preincubation of arteries with insulin significantly reduced the contractile effect of NE by 20% in WKY but not SHR rats. In SHR, the effect of insulin to reduce NE-mediated vasoconstriction became evident when insulin pretreatment was accompanied by ET-1 receptor blockade (BQ-123, BQ-788). Similar results were observed during treatment with the MEK inhibitor PD-98059. In addition, insulin-stimulated secretion of ET-1 from primary endothelial cells was significantly reduced by pretreatment of cells with PD-98059 (but not wortmannin). We conclude that insulin resistance in SHR is accompanied by endothelial dysfunction in mesenteric vessels with impaired PI3-kinase-dependent NO production and enhanced MAPK-dependent ET-1 secretion. These results may reflect pathophysiology in other vascular beds that directly contribute to elevated peripheral vascular resistance and hypertension.
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PMID:Insulin resistance in spontaneously hypertensive rats is associated with endothelial dysfunction characterized by imbalance between NO and ET-1 production. 1579 94

Phenylarsine oxide (PAO), a trivalent arsenical compound, stimulated [Ca2+]i elevation in rat neutrophils in a Ca2+-containing medium but caused no appreciable response in a Ca2+-free medium. PAO also induced external Mn2+ entry, which was inhibited by N-acetyl-L-cysteine (NAC), but failed to elicit any appreciable Ba2+ and Sr2+ entry. Pretreatment of neutrophils with thiol-reducing agents including dithiothreitol (DTT), NAC, 2,3-dimercapto-1-propanol (DMP), 2,3-dimercaptopropane-1-sulfonic acid (DMPS) and tris-(2-carboxyethyl)phosphine (TCEP), all greatly inhibited PAO-induced [Ca2+]i elevation. Addition of Ni2+ or La3+ followed by PAO stimulation also attenuated the Ca2+ signals in a concentration-dependent manner. PAO had no significant effect on the production of reactive oxygen intermediates (ROI) and nitric oxide (NO) nor did it decrease cellular low molecular weight thiols levels. PAO-induced [Ca2+]i elevation was significantly inhibited by 1-[6-[17beta-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U-73122), the inhibitor of phospholipase C-coupled processes, genistein, a general tyrosine kinase inhibitor, phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator, calyculin A, a cortical actin stabilizer, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY 294002), a phosphoinositide 3-kinase inhibitor, 1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole (SKF-96365), and cis-N-(2-phenylcyclopentyl)azacyclotridec-1-en-2-amine (MDL-12,330A), the blockers of receptor-gated and store-operated Ca2+ channels, whereas there was no appreciable effect exerted by aristolochic acid, a phospholipase A2 inhibitor, 7-nitroindazole and N-(3-aminomethyl)benzylacetamidine (1400W), the blockers of NO synthase, and by suspension in a Na+-deprived medium. In contrast, 2-aminoethoxydiphenyl borane (2-APB), the blocker of IP3 receptor and Ca2+ influx, enhanced the PAO-induced response. PAO had no effect on the plasma membrane Ca2+-ATPase (PMCA) activity in the pharmacological isolated neutrophil preparation and the neutrophil membrane fractions. These results indicate that PAO stimulates [Ca2+]i rise in rat neutrophils mainly through the oxidation of vicinal thiol groups on the cell surface membrane to activation of a non-store operated Ca2+ entry (non-SOCE) without affecting the activity of PMCA and the plasmalemmal Na+/Ca2+ exchanger.
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PMID:Stimulation of intracellular Ca2+ elevation in neutrophils by thiol-oxidizing phenylarsine oxide. 1579 43

The present study was conducted to determine effects of U0126, a specific inhibitor of mitogen-activated kinase kinase 1/2, on production of nitric oxide (NO) in RAW264.7 macrophage cells. U0126 significantly enhanced NO production in lipopolysaccharide (LPS) but not CpG DNA or interferon-gamma-stimulated RAW264.7 cells. In contrast, U0124, a negative control for U0126, did not affect LPS-induced NO production. Further, a series of inhibitors of p38, phosphatidyl-inositol 3-kinase and Janus tyrosine kinase rather caused suppression in LPS-stimulated RAW264.7 cells. U0126 was found to definitely inhibit phosphorylation of extracellular signal-regulated kinase (Erk) 1/2 and augment the levels of inducible type of NO synthase. Antisense oligonucleotides of Erk1/2 also augmented LPS-induced NO production. Inactivation of Erk1/2 by U0126 furthermore inhibited LPS-induced activating protein-1 activation, but not nuclear factor-kappaB activation. The results suggest that Erk1/2 might negatively regulate NO production in LPS-stimulated RAW264.7 cells.
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PMID:Inhibition of extracellular signal-regulated kinase 1/2 augments nitric oxide production in lipopolysaccharide-stimulated RAW264.7 macrophage cells. 1605 Oct 71

A possible role of nitric oxide (NO) in adult neurogenesis has been suggested based on anatomical findings showing that subventricular zone (SVZ) neuroblasts are located close to NO-producing cells, and on the known antiproliferative actions of NO in many cell types. Experiments have been performed in rodents with systemic and intracerebroventricular administrations of the NO synthase (NOS) inhibitor L-NAME. NOS inhibition leads to significant increases in the number of proliferating cells in the SVZ and olfactory bulb (OB). NO exerts its cytostatic action preferentially on the cell population expressing nestin but not betaIII-tubulin, which may correspond to the type C cells described in the SVZ. The negative effect of NO on SVZ cell proliferation has also been confirmed in SVZ primary cultures. An inhibition of the tyrosine kinase activity of the epidermal growth factor receptor (EGFR) is described as one of the molecular mechanisms responsible for the antiproliferative effect of NO in SVZ cells. Biochemical data supporting this conclusion has been obtained using the neuroblastoma cell line NB69, which endogenously expresses the EGFR. In these cells, the antimitotic action of NO occurs upon inhibition of the EGFR tyrosine phosphorylation, probably by a direct S-nitrosylation of the receptor. The latest published reports on NO and neurogenesis indicate that NO physiologically participates in the control of adult neurogenesis by modulating the proliferation and fate of the SVZ progenitor cells. These effects might be partially due to a direct inhibition of the EGFR by S-nitrosylation.
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PMID:Role of nitric oxide in subventricular zone neurogenesis. 1611 62

The application of fluid shear stress to endothelial cells elicits the formation of nitric oxide (NO) and phosphorylation of the endothelial NO synthase (eNOS). Shear stress also elicits the enhanced tyrosine phosphorylation of endothelial proteins, especially of those situated in the vicinity of cell-cell contacts. Since a major constituent of these endothelial cell-cell contacts is the platelet endothelial cell adhesion molecule-1 (PECAM-1) we assessed the role of PECAM-1 in the activation of eNOS. In human endothelial cells, shear stress induced the tyrosine phosphorylation of PECAM-1 and enhanced the association of PECAM-1 with eNOS. Endothelial cell stimulation with shear stress elicited the phosphorylation of Akt and eNOS as well as of the AMP-activated protein kinase (AMPK). While the shear-stress-induced tyrosine phosphorylation of PECAM-1 as well as the serine phosphorylation of Akt and eNOS were abolished by the pre-treatment of cells with the tyrosine kinase inhibitor PP1 the phosphorylation of AMPK was unaffected. Down-regulation of PECAM-1 using a siRNA approach attenuated the shear-stress-induced phosphorylation of Akt and eNOS, as well as the shear-stress-induced accumulation of cyclic GMP levels while the shear-stress-induced phosphorylation of AMPK remained intact. A comparable attenuation of Akt and eNOS (but not AMPK) phosphorylation and NO production was also observed in endothelial cells generated from PECAM-1-deficient mice. These data indicate that the shear-stress-induced activation of Akt and eNOS in endothelial cells is modulated by the tyrosine phosphorylation of PECAM-1 whereas the shear-stress-induced phosphorylation of AMPK is controlled by an alternative signaling pathway.
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PMID:Role of PECAM-1 in the shear-stress-induced activation of Akt and the endothelial nitric oxide synthase (eNOS) in endothelial cells. 1611 42

Endothelial membrane-bound thrombomodulin is a high affinity receptor for thrombin to inhibit coagulation. We previously demonstrated that the thrombin-thrombomodulin complex restrains cell proliferation mediated through protease-activated receptor (PAR)-1. We have now tested the hypothesis that thrombomodulin transduces a signal to activate the endothelial nitric-oxide synthase (NOS3) and to modulate G protein-coupled receptor signaling. Cultured human umbilical vein endothelial cells were stimulated with thrombin or a mutant of thrombin that binds to thrombomodulin and has no catalytic activity on PAR-1. Thrombin and its mutant dose dependently activated NO release at cell surface. Pretreatment with anti-thrombomodulin antibody suppressed NO response to the mutant and to low thrombin concentration and reduced by half response to high concentration. Thrombin receptor-activating peptide that only activates PAR-1 and high thrombin concentration induced marked biphasic Ca2+ signals with rapid phosphorylation of PLC(beta3) and NOS3 at both serine 1177 and threonine 495. The mutant thrombin evoked a Ca2+ spark and progressive phosphorylation of Src family kinases at tyrosine 416 and NOS3 only at threonine 495. It activated rapid phosphatidylinositol-3 kinase-dependent NO synthesis and phosphorylation of epidermal growth factor receptor and calmodulin kinase II. Complete epidermal growth factor receptor inhibition only partly reduced the activation of phospholipase Cgamma1 and NOS3. Prestimulation of thrombomodulin did not affect NO release but reduced Ca2+ responses to thrombin and histamine, suggesting cross-talks between thrombomodulin and G protein-coupled receptors. This is the first demonstration of an outside-in signal mediated by the cell surface thrombomodulin receptor to activate NOS3 through tyrosine kinase-dependent pathway. This signaling may contribute to thrombomodulin function in thrombosis, inflammation, and atherosclerosis.
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PMID:Endothelial thrombomodulin induces Ca2+ signals and nitric oxide synthesis through epidermal growth factor receptor kinase and calmodulin kinase II. 1612 27

The role of nitric oxide (NO) in various systems of the body has gained prominence since the last decade. The dual role of NO either as a toxic or protective molecule depends on the concentrations of NO being produced, the isoform of NO synthase involved and the type of cell in which NO produced. The protective roles of NO appear to be mediated via cross talk between neurotrophic pathways. In view of this, in this paper, the role of NO in the enteric system is discussed with respect to neuronal nitric oxide synthase expression in neurons associated with the gut and the nerve growth factor and its receptor, tyrosine kinase A expression in the lamina epithelialis.
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PMID:Neuronal nitric oxide synthase and nerve growth factor expression in the enteric nervous system. 1619 97

Melatonin, which is synthesized in the pineal gland and other tissues, has a variety of physiological, immunological, and biochemical functions. It is a direct scavenger of free radicals and has indirect antioxidant effects due to its stimulation of the expression and activity of antioxidative enzymes such as glutathione peroxidase, superoxide dismutase and catalase, and NO synthase, in mammalian cells. Melatonin also reduces serum lipid levels in mammalian species, and helps to prevent oxidative stress in diabetic subjects. Long-term melatonin administration to diabetic rats reduced their hyperlipidemia and hyperinsulinemia, and restored their altered ratios of polyunsaturated fatty acid in serum and tissues. It was recently reported that melatonin enhanced insulin-receptor kinase and IRS-1 phosphorylation, suggesting the potential existence of signaling pathway cross-talk between melatonin and insulin. Because TNF-alpha has been shown to impair insulin action by suppressing insulin receptor-tyrosine kinase activity and its IRS-1 tyrosine phosphorylation in peripheral tissues such as skeletal muscle cells, it was speculated that melatonin might counteract TNF-alpha-associated insulin resistance in type 2 diabetes. This review will focus on the physiological and metabolic effects of melatonin and highlight its potential use for the treatment of cholesterol/lipid and carbohydrate disorders.
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PMID:Metabolic effects of melatonin on oxidative stress and diabetes mellitus. 1621 26

Resveratrol (trans-3, 4', 5-trihydroxy stilbene), a phytoalexin found in grape skins and red wine, has been reported to have a wide range of biological and pharmacological properties. It has been speculated that resveratrol may have cardioprotective activity. The objective of our study was to investigate the effects of resveratrol on intracellular calcium concentration ([Ca(2+)](i)) in rat ventricular myocytes. [Ca(2+)](i) was detected by laser scanning confocal microscopy. The results showed that resveratrol (15~60 mumol/L) reduced [Ca(2+)](i) in normal and Ca(2+)-free Tyrode's solution in a concentration-dependent manner. The effects of resveratrol on [Ca(2+)](i) in normal Tyrode's solution was partially inhibited by pretreatment with sodium orthovanadate (Na3VO4, 1.0 mmol/L, P<0.01), an inhibitor of protein tyrosine phosphatase, or L-type Ca(2+) channel agonist Bay K8644 (10 mumol/L, P<0.05), but could not be antagonized by NO synthase inhibitor L-NAME (1.0 mmol/L). Resveratrol also markedly inhibited the ryanodine-induced [Ca(2+)](i) increase in Ca(2+)-free Tyrode's solution (P<0.01). When Ca(2+) waves were produced by increasing extracellular Ca(2+) concentration from 1 to 10 mmol/L, resveratrol (60 mumol/L) could reduce the velocity and duration of propagating waves, and block the propagating waves of elevated [Ca(2+)](i). These results suggest that resveratrol may reduce the [Ca(2+)](i) in isolated rat ventricular myocytes. The inhibition of voltage-dependent Ca(2+) channel and tyrosine kinase, and alleviation of Ca(2+) release from sarcoplasmic reticulum (SR) are possibly involved in the effects of resveratrol on rat ventricular myocytes. These findings could help explain the protective activity of resveratrol against cardiovascular disease.
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PMID:Resveratrol reduces intracellular free calcium concentration in rat ventricular myocytes. 1622 Jan 98

Sphingosine 1-phosphate (S1P) is a platelet-derived sphingolipid that activates G protein-coupled S1P receptors and initiates a broad range of responses in vascular endothelial cells. The small GTPase Rac1 is implicated in diverse S1P-modulated cellular responses in endothelial cells, yet the molecular mechanisms involved in S1P-mediated Rac1 activation are incompletely understood. We studied the pathways involved in S1P-mediated Rac1 activation in bovine aortic endothelial cells (BAEC) and found that S1P-induced Rac1 activation is impaired following chelation of G protein betagamma subunits by transfection of betaARKct. Treatment with the Src tyrosine kinase inhibitor PP2 completely attenuated S1P-mediated Rac1 activation; however, pretreatment of BAEC with wortmannin, an inhibitor of phosphoinositide (PI) 3-kinase, had no effect on Rac1 activation while completely blocking S1P-induced Akt phosphorylation. We used Rac1-specific small interfering RNA (siRNA) duplexes to "knock down" endogenous Rac1 expression and found that siRNA-mediated Rac1 knockdown significantly impaired basal as well as S1P-induced phosphorylation of protein kinase Akt, as well as several downstream targets of Akt including endothelial nitric-oxide synthase and glycogen synthase kinase 3beta. By contrast, S1P-induced phosphorylation of the mitogen-activated protein kinases ERK1/2 was unperturbed by siRNA-mediated Rac1 knockdown. We found that overexpression of the Rac1 guanine nucleotide exchange factor (GEF) Tiam1 markedly enhanced Rac1 activity, whereas a dominant negative Tiam1 mutant significantly attenuated S1P-mediated Rac1 activation. Taken together, these studies identify G protein betagamma subunits, Src kinase and the GEF Tiam1 as upstream modulators of S1P-mediated Rac1 activation, and establish a central role for Rac1 in S1P-mediated activation of PI 3-kinase/Akt/endothelial nitric-oxide synthase signaling in vascular endothelial cells.
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PMID:Rac1 modulates sphingosine 1-phosphate-mediated activation of phosphoinositide 3-kinase/Akt signaling pathways in vascular endothelial cells. 1633 42


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