Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Exposure of primary cultures of neonatal rat cortical astrocytes to bacterial lipopolysaccharide (LPS) results in the appearance of nitric oxide synthase (NOS) activity. The induction of NOS, which is blocked by actinomycin D, is directly related to the duration of exposure and dose of LPS, and a 2-hr pulse can induce enzyme activity. Cytosol from LPS-treated astrocyte cultures, but not from control cultures, produces a Ca(2+)-independent conversion of L-arginine to L-citrulline that can be completely blocked by the specific NOS inhibitor NG-monomethyl-L-arginine. The induced NOS activity exhibits an apparent Km of 16.5 microM for L-arginine and is dependent on NADPH, FAD, and tetrahydrobiopterin. LPS also induces NOS in C6 glioma cells and microglial cultures but not in cultured cortical neurons. The expression of NOS in astrocytes and microglial cells has been confirmed by immunocytochemical staining using an antibody to the inducible NOS of mouse macrophages and by histochemical staining for NADPH diaphorase activity. We conclude that glial cells of the central nervous system can express an inducible form of NOS similar to the inducible NOS of macrophages. Inducible NOS in glia may, by generating nitric oxide, contribute to the neuronal damage associated with cerebral ischemia and/or demyelinating diseases.
 ...
PMID:Induction of calcium-independent nitric oxide synthase activity in primary rat glial cultures. 127 98

A calmodulin-dependent nitric oxide synthase was significantly induced in the liver of rats treated intravenously with heat-killed Propionibacterium acnes and 5 days later with Escherichia coli lipopolysaccharide. The apparent calmodulin-dependent and -independent isozymes were separated by Mono Q column chromatography after their partial purification by 2',5'-ADP-agarose affinity chromatography. Both enzymes had a molecular weight of 125,000 as determined by SDS-polyacrylamide gel electrophoresis and required NADPH, tetrahydrobiopterin, and dithiothreitol as cofactors. Their activities were completely inhibited by the specific nitric oxide synthase inhibitors NG-monomethyl-L-arginine and N omega-nitro-L-arginine at 80 and 800 microM, respectively. The peptide maps of these two isozymes with lysylendopeptidase and their reverse-phase column chromatographic profiles were indistinguishable. In the presence of bovine calmodulin, the purified calmodulin-dependent isozyme behaved as a calmodulin-independent isozyme on Mono Q column chromatography. The purified calmodulin-independent isozyme was converted to a calmodulin-dependent isozyme by EDTA and EGTA. Calmodulin blot analysis using 125I-calmodulin showed that the two isozymes bound calmodulin equally efficiently.
 ...
PMID:Identification of inducible calmodulin-dependent nitric oxide synthase in the liver of rats. 128 Nov 57

Macrophages activated by exposure to cytokines and/or to endotoxin produce nitric oxide (NO.), a free radical that is a mediator of the host response to infection. Activation induces the expression of nitric oxide synthase, the enzyme that catalyzes formation of NO. from L-arginine and molecular oxygen. We report the cloning of a cDNA encoding the inducible nitric oxide synthase from a murine macrophage cell line, RAW264.7, exposed to interferon-gamma and lipopolysaccharide. Oocytes injected with mRNA transcribed from this cDNA demonstrate arginine-dependent production of nitrite, a stable metabolite of NO.. Nitric production is blocked by the enzyme inhibitor, NG-monomethylarginine, and is independent of calcium/calmodulin. RAW264.7 cells demonstrate rapid accumulation of the nitric oxide synthase-encoding mRNAs upon activation. Comparison of the deduced amino acid sequence to the calcium/calmodulin-dependent nitric oxide synthase previously purified (Bredt, D. S., and Synder, S.H. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 682-685) and cloned (Bredt, D. S., Hwang, P. M., Glatt, C. E., Lowenstein, C., Reed, R. R., and Synder, S. H. (1991) nature 351, 714-718) from rat brain identifies shared binding sites for the cofactors NADPH and flavins in the C-terminal half of both proteins and an additional conserved region near the N terminus that may recognize L-arginine and/or contribute to the active site.
 ...
PMID:Molecular cloning and functional expression of an inducible nitric oxide synthase from a murine macrophage cell line. 137 7

Primary astrocyte cultures, C6 glioma cells, and N18 neuroblastoma cells were assayed for nitric oxide synthase (NOS) activity with a bioassay of cyclic GMP production in RFL-6 fibroblasts. Treatment of astrocyte cultures for 16-18 h with lipopolysaccharide (LPS) induced NOS-like activity that was L-arginine and NADPH dependent, Ca2+ independent, and potentiated by superoxide dismutase. Induction was evident after 4 h, was dependent on the dose of LPS, and required protein synthesis. Treatment of astrocyte cultures with leucine methyl ester reduced microglial cell contamination from 7 to 1%, with a loss of 44% of NOS-like activity. C6 cells treated with LPS also showed Ca(2+)-independent and L-arginine-dependent NOS-like activity. N18 cells demonstrated constitutive Ca(2+)-dependent NOS-like activity that was not enhanced by LPS induction. These data indicate that NOS-like activity can be induced in microglia, astrocytes, and a related glioma cell line as it can in numerous other cell types, but not in neuron-like N18 cells.
 ...
PMID:Induction of nitric oxide synthase in glial cells. 137 33

In the skin, wounding initiates a complex array of physiological processes mediated by growth factors and inflammatory mediators which stimulate tissue repair and protect against infection. We report that primary cultures of human keratinocytes and a mouse keratinocyte cell line respond to the inflammatory stimuli gamma-interferon and lipopolysaccharide or tumor necrosis factor-alpha by producing nitric oxide and hydrogen peroxide, two reactive mediators that are important in nonspecific host defense. Nitric oxide is produced by the l-arginine- and NADPH-dependent enzyme, nitric oxide synthase. In murine keratinocytes, optimal enzymatic activity was found to be dependent on Ca2+ and calmodulin as well as on glutathione. Inflammatory mediators were also found to inhibit the growth of keratinocytes, an effect that could be reversed by a nitric oxide synthase inhibitor. Epidermal growth factor (EGF), which promotes wound healing by stimulating cellular proliferation, was found to be a potent antagonist of reactive nitrogen and reactive oxygen intermediate production by keratinocytes. EGF also reversed the growth inhibitory actions of the inflammatory mediators. These data suggest that nitric oxide produced by keratinocytes is important in the control of cellular proliferation during wound healing. Our findings that EGF effectively regulates the production of free radicals by keratinocytes may represent an important pathway by which this growth factor not only stimulates epidermal cell proliferation but also facilitates the resolution of inflammation following wounding.
 ...
PMID:Epidermal growth factor suppresses nitric oxide and hydrogen peroxide production by keratinocytes. Potential role for nitric oxide in the regulation of wound healing. 138 21

The cytosol fraction of J774-1 murine macrophages activated with lipopolysaccharide (LPS) + interferon-gamma (IFN-gamma) was found to nitrosate a wide range of secondary and tertiary amines. The reaction was dependent on L-arginine and NADPH. The optimal pH for nitrosation was 7.2-7.3. Nitrosation was inhibited by arginine derivatives such as NG-monomethyl-L-arginine and NG-nitro-L-arginine, well-known inhibitors of nitric oxide (NO) synthase. These results indicate that nitrosation is mediated by NO synthase, which catalyzes formation of NO and L-citrulline from L-arginine. Nitrosamine formation also required oxygen and was inversely correlated with the basicity of nitrosatable amines. The nitrosation was inhibited by oxyhemoglobin, an NO trapping agent, and enhanced by superoxide dismutase, which stabilizes NO. LPS + IFN-gamma induced approximately 500-600 times greater nitrosation activity than that of non-activated macrophages. Macrophages treated with LPS alone exhibited 3-4 times greater nitrosation activity than untreated macrophages, whereas macrophages treated with IFN-gamma alone did not show enhanced nitrosation activity. A combination of the cytosols from macrophages treated with LPS alone and IFN-gamma alone did not nitrosate morpholine as rapidly as the cytosol of macrophages treated with both compounds together. The activity for forming L-citrulline and nitrite/nitrate from L-arginine was markedly induced by treatment with either LPS alone or LPS + IFN-gamma but not with IFN-gamma. Those results suggest that some other factor(s) in addition to NO synthase is involved for efficient nitrosation by the macrophage cytosol. This factor(s) was not induced in macrophages by either LPS- or IFN-gamma alone, but was induced only in the presence of the two compounds.
 ...
PMID:L-arginine-dependent formation of N-nitrosamines by the cytosol of macrophages activated with lipopolysaccharide and interferon-gamma. 171 76

A soluble nitric oxide (NO) synthase activity was purified 426-fold from a mouse macrophage cell line activated with interferon gamma and bacterial lipopolysaccharide by sequential anion-exchange, affinity, and gel filtration chromatography. SDS/PAGE of the purified NO synthase gave three closely spaced silver-staining protein bands between 125 and 135 kDa. When assayed in the presence of L-arginine, NADPH, tetrahydrobiopterin, FAD, and reduced thiol, purified NO synthase had a specific activity of 1313 nmol of NO2- plus NO3- per min per mg. The apparent Km of the enzyme for L-arginine and NADPH was 2.8 and 0.3 microM, respectively. Addition of calcium ions with or without calmodulin did not increase the activity of the purified enzyme, and NO synthesis was not altered by calmodulin inhibitors. Gel filtration chromatography indicated that the induced NO synthase was catalytically competent as a dimer of approximately 250 kDa but could be dissociated into inactive monomers of approximately 130 kDa in the absence of L-arginine, FAD, and tetrahydrobiopterin. Upon heat denaturation, NO synthase released 1.1 mol of FAD and 0.55 mol of FMN per mol of 130-kDa subunit. Thus, inducible macrophage NO synthase differs in several respects from constitutive NO synthases and is one of very few eukaryotic enzymes containing both FAD and FMN.
 ...
PMID:Purification and characterization of the cytokine-induced macrophage nitric oxide synthase: an FAD- and FMN-containing flavoprotein. 171 79

A number of agents capable of interfering with oxidative events were found to inhibit, in a dose-dependent manner, DNA synthesis in isolated human peripheral blood lymphocytes stimulated with phytohaemagglutinin, or phorbol myristate acetate plus ionomycin. These inhibitory substances were: the iron chelators desferrioxamine and desferrithiocin; the electron acceptor ferricyanide; the anti-oxidant nordihydroguaiaretic acid; ebselen, an agent with glutathione peroxidase-like activity; and diphenylene iodonium, an inhibitor of NADPH-oxidase. The actions of desferrioxamine and desferrithiocin were abolished by prior saturation with iron. Ferrocyanide was much less active in inhibiting human lymphocyte DNA synthesis than its redox partner ferricyanide. Desferrioxamine, ferricyanide and nordihydroguaiaretic acid also inhibited lipopolysaccharide-initiated DNA synthesis in mouse splenocytes in vitro. The common property of these structurally dissimilar agents is their ability to prevent formation of, or detoxify, reactive oxygen species. Thus, the data are consistent with an obligatory role for reactive oxygen formation in human T-cell and mouse B-cell activation at a stage prior to DNA synthesis.
 ...
PMID:Interference with oxidative processes inhibits proliferation of human peripheral blood lymphocytes and murine B-lymphocytes. 176 47

This study shows that stimulating bone marrow-derived macrophages with either lipopolysaccharide (LPS) or the lipopeptide N-palmitoyl-S-(2,3-bis(palmitoyloxy)-(2RS)-propyl)-(R)- cysteinyl-alanyl-glycine (Pam3Cys-Ala-Gly), a synthetic analogue of the N-terminal part of bacterial lipoprotein, leads to the formation of nitric oxide (NO) and nitrite (NO2-), a stable analogue of NO. NO was detected by applying the chemiluminescence method and by measuring the activity of exogenously added soluble guanylate cyclase (GC), which is strongly and selectively activated by NO. Synthesis of NO and NO2- occurs via activation of the L-arginine and NADPH-dependent enzyme(s) present in the cytosol of bone marrow-derived macrophages. No produced by this non-constitutive L-arginine pathway is thought to be responsible for the cytostatic and killing properties of macrophages (Stuehr & Nathan, 1989). Macrophages stimulated either with LPS or Pam3Cys-Ala-Gly exhibited a 6-hr lag time before engaging in nitrite synthesis, a time at which expression of the NO-forming enzyme had already reached its maximum. The regulation of NO and NO2- synthesis during macrophage development seems to differ from that of cytokine synthesis. Whereas cytokine release varies during a culture period up to 20 days, NO synthesis and expression of the NO-forming enzyme remain unaltered. These studies show that, similar to LPS, Pam3Cys-Ala-Gly is a potent activator of 'the oxidative L-arginine pathway' in bone marrow-derived macrophages. Whether both stimuli use the same signal transfer mechanism to induce this pathway and whether NO synthesized by this pathway is involved in the activation of the enzyme guanylate cyclase in macrophages requires clarification.
 ...
PMID:L-arginine-dependent nitric oxide formation and nitrite release in bone marrow-derived macrophages stimulated with bacterial lipopeptide and lipopolysaccharide. 197 43

The murine adenocarcinoma cell line TA 3 synthesized nitrite from L-arginine upon stimulation with gamma-interferon (IFN-gamma) associated with tumor necrosis factor (TNF), and/or bacterial lipopolysaccharide (LPS), but not with IFN-gamma, TNF, or LPS added separately. Induction of the NO2(-)-generating activity caused an inhibition of DNA synthesis in TA 3 cells. This inhibition was prevented by the L-arginine analog N omega-nitro-L-arginine, which inhibited under the same conditions nitrite production by TA 3 cells. The TA 3 M2 subclone, selected for enhanced ribonucleotide reductase activity, was found to be less sensitive than the wild phenotype TA 3 WT to the cytostatic activity mediated by the NO2(-)-generating system. Cytosolic preparations from TA 3 M2 cells treated for 24 or 48 h with IFN-gamma, TNF, and LPS exhibited a reduced ribonucleotide reductase activity, compared to untreated control cells. No reduction in ribonucleotide reductase activity was observed when N omega-nitro-L-arginine was added to treated cells. Addition of L-arginine, NADPH, and tetrahydrobiopterin into cytosolic extracts from 24-h treated TA 3 M2 cells triggered the synthesis of metabolic products from the NO2(-)-generating pathway. This resulted in a dramatic inhibition of the residual ribonucleotide reductase activity present in the extracts. The inhibition was reversed by NG-monomethyl-L-arginine, another specific inhibitor of the NO2(-)-generating activity. No L-arginine-dependent inhibition of ribonucleotide reductase activity was observed using extracts from untreated cells that did not express NO2(-)-generating activity. These results demonstrate that, in an acellular preparation, molecules derived from the NO2(-)-generating pathway exert an inhibitory effect on the ribonucleotide reductase enzyme. This negative action might explain the inhibition of DNA synthesis induced in adenocarcinoma cells by the NO2(-)-generating pathway.
 ...
PMID:Alterations of ribonucleotide reductase activity following induction of the nitrite-generating pathway in adenocarcinoma cells. 211 5


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