Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0406810 (NAME)
 13,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelial cell nitric oxide synthase (ECNOS) is a membrane-associated enzyme that generates endothelium-derived relaxing factor/nitric oxide (EDRF/NO) from L-arginine. We have suggested, from the cloning of the bovine ECNOS cDNA, that the presence of an N-myristoylation consensus sequence may impart its membrane localization since cytosolic forms of NOS do not contain such domains. To test the hypothesis that N-myristoylation is necessary for particulate ECNOS, we performed site-directed mutagenesis of the myristic acid acceptor site, Gly-2, and changed the glycine codon to alanine by a single nucleotide substitution. Expression of wild-type ECNOS in COS cells resulted in greater than 95% of the enzymatic activity in crude membrane fractions (as measured by the conversion of [3H]L-arginine to [3H]L-citrulline). In contrast, expression of the Gly-2 to Ala-2 mutant (G2A) demonstrated 8% ECNOS activity in membranes and 92% in the cytosol. The back mutation (from Ala-2 to Gly-2, A2G) restored ECNOS activity to the particulate fraction as seen with the wild type. Both wild-type membrane ECNOS and cytosolic G2A ECNOS activities were dependent on NADPH and calcium and were inhibited to the same extent by NG-monomethyl L-arginine (L-NMMA) and NG-nitro-L-arginine methyl ester (L-NAME). Moreover, kinetic analysis of these enzymes revealed similar Kms for L-arginine (2-4 microM, n = 3), demonstrating that the mutation did not affect ECNOS function. Thus, N-myristoylation is necessary for the membrane localization of ECNOS and may be of special significance for the basal or flow-induced production of NO by the endothelium.
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PMID:Mutation of N-myristoylation site converts endothelial cell nitric oxide synthase from a membrane to a cytosolic protein. 768 Feb 89

We have identified two types of polymorphism at the CAR (cell adhesion regulator) locus. One is a conventional TaqI polymorphism and the other is an insertion/deletion polymorphism in the coding region. One has the nucleotide sequence AGTGAGGCA (Ser-Gln-Ala) at nt 271-279, whereas the variant has ACAC-AGTGAGGCCCA (Thr-Gln-Ser-Gly-Pro). Although it is not clear whether this variation of amino acids affects the biological function of the gene product, this variant was detected in nine chromosomes among 30 unrelated Japanese individuals. Genetic linkage analysis based on the genotypes of TaqI polymorphism in CEPH families revealed close linkage of CAR to D16S7 and D16S154, which are located in the peritelomeric region of the long arm of chromosome 16.
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PMID:The cell adhesion regulator (CAR) gene, TaqI and insertion/deletion polymorphisms, and regional assignment to the peritelomeric region of 16q by linkage analysis. 809 8

We investigated the effects of age and NG-nitro-L-arginine methyl ester (L-NAME) on glutamate receptor systems and immunophilin in Fischer rat brain using receptor autoradiography. [3H]MK-801, [3H]glycine, sodium-dependent [3H]D-aspartate and [3H]FK-506 were used to label N-methyl-D-aspartate (NMDA) receptors, glycine receptors, excitatory amino acid transport sites and FK-506 binding proteins (FKBP), respectively. [3H]Glycine and sodium-dependent [3H]D-aspartate binding significantly reduced in the cerebral cortex, striatum, hippocampus, thalamus, substantia nigra and cerebellum of aged (24-month-old) rats in comparison with adult (6-month-old) animals. In contrast, [3H]MK-801 and [3H]FK-506 binding showed no significant changes in most brain regions of aged rats. Intraperitoneal chronic treatment with L-NAME (5 mg/kg, once a day for 4 weeks) showed no conspicuous changes in these binding sites in most brain areas of aged rats. In the cerebellum, however, this treatment showed a significant change in both [3H]MK-801 and sodium-dependent [3H]D-aspartate binding in aged rats. These results demonstrate that glycine receptors and excitatory amino acid transport sites are more susceptible to aging processes than NMDA receptors and FKBP. Furthermore, our findings may suggest a possible role of nitric oxide in the regulation of cerebellum during aging processes.
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PMID:Effect of NG-nitro-L-arginine on age-related changes of glutamate receptor systems and immunophilin in rats. 938 86

The signaling pathway initiated by factor Xa on vascular endothelial cells was investigated. Factor Xa stimulated a 5- to 10-fold increased release of nitric oxide (NO) in a dose-dependent reaction (0.1-2.5 microG/ml) unaffected by the thrombin inhibitor hirudin but abolished by active site inhibitors, tick anticoagulant peptide, or Glu-Gly-Arg-chloromethyl ketone. In contrast, the homologous clotting protease factor IXa or another endothelial cell ligand, fibrinogen, was ineffective. A factor Xa inter-epidermal growth factor synthetic peptide L (83)FTRKL(88) (G) blocking ligand binding to effector cell protease receptor-1 inhibited NO release by factor Xa in a dose-dependent manner, whereas a control scrambled peptide KFTGRLL was ineffective. Catalytically active factor Xa induced hypotension in rats and vasorelaxation in the isolated rat mesentery, which was blocked by the NO synthase inhibitor L-N(G)-nitroarginine methyl ester (L-NAME) but not by D-NAME. Factor Xa/NO signaling also produced a dose-dependent endothelial cell release of interleukin 6 (range 0.55-3.1 ng/ml) in a reaction inhibited by L-NAME and by the inter-epidermal growth factor peptide Leu(83)-Leu(88) but unaffected by hirudin. Maximal induction of interleukin 6 mRNA required a brief, 30-min stimulation with factor Xa, unaffected by subsequent addition of tissue factor pathway inhibitor. These data suggest that factor Xa-induced NO release modulates endothelial cell-dependent vasorelaxation and cytokine gene expression. This pathway requiring factor Xa binding to effector cell protease receptor-1 and a secondary step of ligand-dependent proteolysis may preserve an anti-thrombotic phenotype of endothelium but also trigger acute phase responses during activation of coagulation in vivo.
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PMID:Hypotension and inflammatory cytokine gene expression triggered by factor Xa-nitric oxide signaling. 953 8

The involvement of platelets in neovascularization was investigated in the matrigel tube formation assay, an in vitro model of angiogenesis. Platelets promoted the formation of capillary-like structures (expressed as relative tube area) number- and time-dependently. Relative tube area increased from 0.98+/-0.02 (n = 8) in the presence of 6.25 x 10(4), to 3.21+/-0.12 (n=8) in the presence of 10(6) platelets/well compared to 0.54+/-0.04 (n=8) in their absence. This increase was unaffected by acetyl salicylic acid (ASA), apyrase, and hirudin. Photographs from representative experiments, showed that platelets adhered along the differentiating endothelium. Addition of alpha-thrombin (0.1-1 i.u. ml(-1)), the nitric oxide (NO) donor sodium nitroprusside (SNP; 1-100 microM) or the NO synthase inhibitor, L-NG-arginine-methylester (L-NAME, 30-300 microM) to the assay, had no effect on tube formation compared to that seen with platelets alone. Neuraminidase (0.01 i.u./10(7) platelets), which strips sialic acid residues from membrane glycoproteins, abolished the promoting effect of platelets on tube formation. The relative tube area in the presence of neuraminidase-treated platelets was 0.81+/-0.03 (n = 8), in the presence of untreated platelets 1.69+/-0.09, P<0.001 (n=8) and in the absence of platelets, 0.80+/-0.04 (n=8). The tetrapeptide Arg-Gly-Asp-Ser (RGDS; 20-200 microM) which inhibits von Willebrand factor, fibrinogen and fibronectin-mediated adhesion, had no effect on the promoting effect of platelets on tube formation. These results indicate that platelets promote angiogenesis in vitro. This effect is largely independent from activation by alpha-thrombin, is not modified by manipulating NO and prostaglandin metabolism and proceeds possibly through adhesion of the platelets to the differentiating endothelium.
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PMID:Evidence that platelets promote tube formation by endothelial cells on matrigel. 986 54

In this study we analyzed two ways of retargeting of Ad-vectors to human pancreatic carcinoma with the aim of enhancing the gene transfer efficiency. First, we analyzed the expression of the epidermal growth factor receptor (EGFR) on primary, as well as established pancreatic carcinoma cells by flow cytometry which revealed high expression levels of EGFR on the surface of these cells. We showed that EGFR-retargeted entry pathway using a bispecific fusion protein formed by a recombinant soluble form of truncated Coxsackie and Adenovirus Receptor (sCAR) genetically fused with human EGF (sCAR-EGF) redirects them to the EGFR leading to an enhanced gene transfer efficiency to pancreatic carcinoma cells. Since flow cytometry revealed absence of CAR expression, but the presence of at least one of both alphav integrins on the pancreatic carcinoma cells, a second way of targeting was investigated using a genetically modified Ad vector which has an RGD (Arg-Gly-Asp)-containing peptide inserted into the HI-loop of the fiber knob. This RGD targeted Ad (AdlucRGD) revealed efficient CAR-independent infection by allowing binding to cellular integrins resulting in a dramatic enhancement of gene transfer. These findings have direct relevance for Ad-vector based gene therapy strategies for pancreatic carcinoma.
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PMID:Improved gene transfer efficiency to primary and established human pancreatic carcinoma target cells via epidermal growth factor receptor and integrin-targeted adenoviral vectors. 1143 31

1. Endomorphins 1 and 2, endogenous ligands for the mu-opioid receptor, and nociceptin (orphanin FQ; OFQ), an endogenous ligand for the ORL1 receptor, have vasodilator activity in the vascular bed of the hindquarters of the rat. In the present study, the role of nitric oxide (NO), vasodilator prostaglandins and the opening of KATP channels in mediating vasodilator responses to these novel agonists was investigated in the rat. 2. Under constant-flow conditions, injections of endomorphins 1 and 2, PL017 ([N-MePhe3,D-Pro4]-morphiceptin), nociceptin and Tyr-D-Ala-Gly-MePhe-Gly(ol)-enkephalin (DAMGO) produced dose-dependent decreases in hindquarters perfusion pressure. Vasodilator responses to endomorphin 1 and 2, acetylcholine and adrenomedullin, were attenuated by the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) at a time when vasodilator responses to nociceptin, adrenomedullin and the NO donor diethylamine/NO were not altered. 3. Vasodilator responses to endomorphins 1 and 2, nociceptin, PL017 and DAMGO were not altered after administration of sodium meclofenamate at a time when vasodilator responses to arachidonic acid were reduced significantly or after administration of U-37883A at a time when vasodilator responses to levcromakalim were reduced significantly. 4. The results of these studies indicate that vasodilator responses to endomorphins 1 and 2, PL017 and DAMGO are mediated, in large part, by the release of NO, whereas vasodilator responses to nociceptin are mediated by an L-NAME-insensitive mechanism. Moreover, these results demonstrate that the vasodilator responses to these peptides are not due to the release of vasodilator prostaglandins or the opening of KATP channels in the hindquarters vascular bed of the rat.
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PMID:Role of nitric oxide in mediating vasodilator responses to opioid peptides in the rat. 1190 89

1. Infusion of the amino acid glycine leads to an increase in effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) by a mechanism that possibly involves stimulation of nitric oxide (NO). Because NO also increases proximal tubular fluid output (Vprox) by inhibition of proximal tubular Na+ reabsorption and modulation of the tubuloglomerular feedback system, we hypothesized that glycine would increase Vprox as measured by lithium clearance (CLi). 2. In the first series of experiments, the effect of glycine infusion (4 mg/min) was examined in conscious, unstressed, chronically catheterized rats. In an additional series of experiments, the effect of glycine was examined under similar conditions in rats pretreated with a NO synthase (NOS) inhibitor (NG-nitro-L-arginine methyl ester (L-NAME), 2.5 microg/min). 3. Glycine significantly increased ERPF (from 3268 to 4018 microL/min per 100 g bodyweight (BW)), GFR (from 874 to 1009 microL/min per 100 g BW), CLi (from 275 to 461 microL/min per 100 g BW) and Na+ clearance (CNa; from 2.9 to 14.0 microL/min per 100 g BW). Fractional excretion of lithium (FELi; from 32 to 46%) and CNa/CLi (from 0.99 to 2.99%) also rose, indicating inhibition of proximal and distal nephron Na+ reabsorption, respectively. In the rats pretreated with L-NAME, similar haemodynamic and tubular responses to glycine infusion were seen, suggesting that the effects were not mediated by NO. 4. We conclude, that glycine increases ERPF and GFR and it also inhibits proximal and distal nephron Na+ reabsorption leading to an increase in CLi and CNa. There was no indication that any of these effects were mediated by NO.
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PMID:Effects of glycine on glomerular filtration rate and segmental tubular handling of sodium in conscious rats. 1201 Jan 91

alpha-lactorphin (Tyr-Gly-Leu-Phe) lowers blood pressure in conscious adult SHR. This tetrapeptide is originally released from milk protein alpha-lactalbumin by enzymatic hydrolysis. In order to evaluate the antihypertensive mechanisms of alpha-lactorphin, the effects of the tetrapeptide on vascular function were investigated in (30-35 weeks old) spontaneously hypertensive rats (SHR) with established hypertension and age-matched normotensive Wistar-Kyoto (WKY) rats in vitro. In addition, we studied the vascular effects of another structurally related tetrapeptide, beta-lactorphin (Tyr-Leu-Leu-Phe), which originates from milk protein beta-lactoglobulin. Endothelium-dependent relaxation to acetylcholine (ACh) was reduced in mesenteric arterial preparations of SHR as compared to those of WKY. In SHR, the ACh-induced relaxation was augmented by alpha-lactorphin or beta-lactorphin. The role of nitric oxide (NO) is suggested, since this improvement was abolished by the NO synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). Simultaneous potassium channel inhibitor tetraethylammonium (TEA) elicited no additional effect on the ACh-induced relaxation. The cyclooxygenase inhibitor diclofenac did not attenuate the augmented ACh relaxation induced by alpha-lactorphin or beta-lactorphin, suggesting that endothelial vasodilatory prostanoids were not involved in the effect of the tetrapeptides. Endothelium-independent relaxation to the NO donor sodium nitroprusside (SNP) was augmented in mesenteric arterial preparations of SHR by simultaneous beta-lactorphin. The tetrapeptides did not alter vascular responses in mesenteric arteries from WKY. In conclusion, both alpha-lactorphin and beta-lactorphin improved vascular relaxation in adult SHR in vitro. The beneficial effect of alpha-lactorphin was directed towards endothelial function, whereas beta-lactorphin also enhanced endothelium-independent relaxation.
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PMID:Alpha-lactorphin and beta-lactorphin improve arterial function in spontaneously hypertensive rats. 1210 90

We studied the actions of the proteinase-activated receptor-2-activating peptide (PAR2-AP) trans-cinnamoyl-LIGRLO-amide (tc-LI) in femoral (FA), renal, and small mesenteric (MA) arterial vessels from C57BL/6 [PAR2 (+/+)] and PAR2 (-/-) mice. The actions of tc-LI were compared with those of the parent PAR2-AP Ser-Leu-Ile-Gly-Arg-Leu-amide (SLIGRL-amide; SLI-NH2). Either SLI-NH2 or tc-LI (0.1-10 microM) induced relaxation of either 9,11-dideoxy-9alpha,11alpha-methanoepoxy-prosta-5Z,13E-dien-1-oic acid (U46619)- or cirazoline-precontracted FA from PAR2 (+/+) in endothelium-intact preparations but did not relax vessels from PAR2 (-/-) mice. This FA relaxation by SLI-NH2 and by tc-LI was inhibited by 1) pretreatment with a combination of L-N(G)-nitroarginine methyl ester (L-NAME) and 1H-[1,2,4]-oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), 2) precontraction with 30 mM KCl, or 3) removal of the endothelium. In contrast, tc-LI caused an L-NAME/ODQ/indomethacin-resistant relaxation of MA from PAR2 (+/+) mice. In contrast with SLI-NH2, tc-LI (>30 microM) contracted arteries from both PAR2 (-/-) and PAR2 (+/+) mice. Pretreatment of tissues with a combination of cyclopiazonic acid plus caffeine reduced significantly tc-LI-induced contractions, whereas nifedipine, CdCl2, and Ca2+-free conditions did not. Inhibitors of vascular muscarinic, alpha1-adrenergic, neurokinin, thromboxane A2, histamine, angiotensin II, or endothelin-1 receptors failed to inhibit contractions by 50 microM tc-LI. At resting tension, SLI-NH2 (>10 microM) contracted all arteries in an endothelium-independent manner but only from PAR2 (+/+) mice. We conclude that the endothelium-dependent vasodilation initiated by SLI-NH2 and tc-LI, but not the endothelium-independent contraction initiated by tc-LI, are due to the activation of PAR2. Indeed, the data from PAR2 (-/-) mice indicate that tc-LI, in addition to activating PAR2, is an agonist of vascular smooth muscle contraction via a receptor different than PAR2.
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PMID:Proteinase-activated receptor-2 (PAR2): vascular effects of a PAR2-derived activating peptide via a receptor different than PAR2. 1243 18


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