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

Analysis of an Aeromonas salmonicida A layer-deficient/O polysaccharide-deficient mutant carrying a Tn5 insertion in the structural gene for A protein (vapA) showed that the abcA gene immediately downstream of vapA had been interrupted by the endogenous insertion sequence element ISAS1. Immunoelectron microscopy showed that O polysaccharides did not accumulate at the inner membrane-cytoplasm interface of this mutant. abcA encodes an unusual protein; it carries both an amino-terminal ATP-binding cassette (ABC) domain showing high sequence similarity to ABC proteins implicated in the transport of certain capsular and O polysaccharides and a carboxyl-terminal potential DNA-binding domain, which distinguishes AbcA from other polysaccharide transport proteins in structural and evolutionary terms. The smooth lipopolysaccharide phenotype was restored by complementation with abcA but not by abcA carrying site-directed mutations in the sequence encoding the ATP-binding site of the protein. The genetic organization of the A. salmonicida ABC polysaccharide system differs from other bacteria. abcA also differs in apparently being required for both O-polysaccharide synthesis and in energizing the transport of O polysaccharides to the cell surface.
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PMID:Endogenous mutagenesis by an insertion sequence element identifies Aeromonas salmonicida AbcA as an ATP-binding cassette transport protein required for biogenesis of smooth lipopolysaccharide. 777 81

Capsaicin stimulates cyclic GMP production via nitric oxide (NO) (or another nitrosyl factor) in dorsal root ganglion (DRG) neurons maintained in culture. The purpose of the present study was to characterize further capsaicin stimulation of cyclic GMP production in DRG cells maintained in culture, investigate other algesic and/or inflammatory agents for effects on cyclic GMP production, and examine cells responsible for NO production and cyclic GMP production. Capsaicin stimulation of cyclic GMP production in DRG cells was dose dependent, receptor mediated, and attenuated by hemoglobin. Prostaglandin E2, substance P, and calcitonin gene-related peptide did not affect basal, capsaicin-stimulated, or bradykinin-stimulated cyclic GMP production. Other inflammatory or algesic agents, including serotonin, histamine, ATP, glutamate, aspartate, and NMDA, did not affect cyclic GMP production. Pretreatment of DRG cells with lipopolysaccharide increased basal cyclic GMP production in neuronal but not in nonneuronal cultures and facilitated stimulation of cyclic GMP production by L-arginine. Capsaicin pretreatment of neuronal DRG cultures, which destroys capsaicin-sensitive (small diameter) afferent neurons, attenuated capsaicin- and bradykinin-stimulated cyclic GMP production but did not affect basal or sodium nitroprusside-stimulated cyclic GMP production. These results indicate that capsaicin elicits production of a nitrosyl factor via capsaicin-sensitive (small diameter) neurons. Capsaicin evoked cyclic GMP production in nonneuronal DRG cultures in the presence but not in the absence of apposed neuronal DRG cultures. Overall, these findings suggest that specific exogenous (or endogenous) substances may stimulate production of a nitrosyl factor(s) by a subset of DRG neurons, and nitrosyl factors produced by these neurons may affect cyclic GMP production in neighboring neuronal or non-neuronal cells.
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PMID:Stimulation of cyclic GMP production via a nitrosyl factor in sensory neuronal cultures by algesic or inflammatory agents. 779 Aug 81

1. Purinoceptor agonist-induced currents in untreated (proliferating) and lipopolysaccharide- (LPS; 100 ng ml-1) treated (non-proliferating) rat microglial cells were recorded by the whole-cell patch-clamp technique. 2. In non-proliferating microglia, adenosine (0.01-100 microM), 2-methylthio ATP (3-3000 nM), ATP (0.1-1000 microM), and ATP-gamma-S (1-10 microM), but not alpha,beta-methylene ATP (alpha,beta-MeATP; 100 microM) produced a slow outward current at a holding potential of 0 mV. When K+ was replaced in the pipette solution by an equimolar concentration of Cs+ (150 mM), the 2-methylthio ATP- (300 nM) induced outward current disappeared. The effect of 2-methylthio ATP (300 nM) did not depend on the presence of extracellular Mg2+ (1 mM). The outward current response to 2-methylthio ATP (300 nM) was larger in proliferating than in non-proliferating microglia. 3. ATP (1-1000 microM) evoked a fast inward current at a holding potential of -70 mV in nonproliferating microglia, while adenosine (100-1000 microM) was inactive. When the effects of ATP were compared at 0 and -70 mV, it became evident that ATP is much more potent in evoking the outward current. 4. The 2-methylthio ATP- (300 nM) induced outward current was blocked by suramin (300 microM), but not by 8-(p-sulphophenyl)-theophylline (100 microM), while the adenosine- (1 microM) induced outward current had the reverse sensitivity to these antagonists. 5. The 2-methylthio ATP- (300 nM) induced outward current was inhibited by inclusion of GDP-beta-S(200 microM) into the pipette solution or by preincubation of microglial cells with pertussis toxin(50 ng ml-1) for 12 h. The 2-methylthio ATP- (300 microM) induced inward current was not changed by intracellular GDP-beta-S (200 microM). The outward current response to adenosine (1 microM) was also abolished after pretreatment with pertussis toxin (50 ng ml-1).6. Rat microglia possess both ATP-sensitive P2y- and adenosine-sensitive P1-purinoceptors. The ATP evoked inward current is mediated by P2y-purinoceptors, while the ATP- and adenosine-evoked outward currents are mediated by P2y- and P1-purinoceptors, respectively. The transduction mechanisms of the outward, but not the inward current activation involve a pertussis toxin-sensitive G protein.
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PMID:Characterization and transduction mechanisms of purinoceptors in activated rat microglia. 781 23

Proteolytic processing of select constituents of the nuclear factor kappa B (NF-kappa B)/inhibitor kappa B alpha (I kappa B) transcription factor system plays an important role in regulating the biological responses of monocytes to pro-inflammatory mediators. Nuclear translocation of NF-kappa B is preceded by the proteolytic degradation of I kappa B alpha, an ankyrin motif-rich inhibitor that traps NF-kappa B in the cytoplasm. In addition, formation of cytoplasmic NF-kappa B/I kappa B alpha complexes in quiescent cells requires constitutive proteolytic processing of p105, another ankyrin motif-rich inhibitory protein from which the p50 subunit of NF-kappa B is generated. We have demonstrated that, following stimulation of human monocytic cells with lipopolysaccharide or tumor necrosis factor-alpha, this critical p105 processing event is up-regulated in concert with the inactivation of I kappa B alpha. Moreover, the degradative loss of both p105 and I kappa B alpha is prevented in cells depleted of intracellular ATP. In activated monocytes, however, I kappa B alpha degradation occurs more rapidly than p105 processing to p50. Together these findings provide direct biochemical evidence that p105 and I kappa B alpha are differentially sensitive targets for inducible proteolysis via ATP-dependent degradative pathways.
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PMID:Proteolytic processing of NF-kappa B/I kappa B in human monocytes. ATP-dependent induction by pro-inflammatory mediators. 781 25

The aim of the current study was to assess the in vitro effects of nickel hydroxy carbonate (NiHC) at noncytotoxic concentrations on the production of cytokines such as tumour necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) in alveolar macrophages (AMs). The effect of NiHC was evaluated in both unstimulated AMs and cells activated by lipopolysaccharide (LPS). Cytotoxicity was related to lactate dehydrogenase release and ATP cell content. The results confirm that NiHC at concentrations of 0.125, 1.25 and 3.125 micrograms NiHC 10(-6) cells was not cytotoxic. The NiHC exposure of unstimulated AMs significantly increased the release of TNF-alpha at all concentrations and that of IL-6 at 1.25 micrograms NiHC 10(-6) cells. LPS addition significantly increased the secretion of both cytokines. However, NiHC did not cause a significant increase in the release of TNF-alpha and IL-6 in LPS-stimulated cells. In conclusion, the ability of NiHC to activate AMs and to release increased amounts of pro-inflammatory mediators may be responsible, at least partly, for inflammation and pneumotoxicity associated with nickel exposure.
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PMID:Nickel hydroxy carbonate increases tumour necrosis factor alpha and interleukin 6 secretion by alveolar macrophages. 782 88

Nuclear factor kappa B (NF-kappa B), consisting of p50 and p65, is bound to a cytoplasmic retention protein, I kappa B, in a resting state, and the stimulation of cells with a variety of inflammatory stimuli induces the dissociation of NF-kappa B from I kappa B and the nuclear translocation of NF-kappa B, thereby activating several genes involved in inflammatory responses, such as interleukin (IL)-6, IL-8, and tumor necrosis factor alpha. In order to elucidate the precise mechanism of NF-kappa B activation, we have established lipopolysaccharide (LPS)-dependent NF-kappa B activation in a cell-free system using plasma membrane-enriched, cytosol, and nuclear fractions extracted from a human monocytic cell line, THP-1, by disruption with sonication followed by a differential centrifugation. The combination of plasma membrane-enriched fraction and cytosol was sufficient to activate NF-kappa B in a LPS/CD14-dependent manner only in the presence of ATP as judged by the binding of NF-kappa B to the IL-8 gene kappa B site on an electrophoretic mobility shift assay. LPS-dependent NF-kappa B activation was inhibited by protein kinase inhibitors, such as staurosporine, herbimycin A, tyrphostin, and genistein, but not mitogen-activated protein kinase substrate, cGMP-dependent protein kinase, cAMP-dependent protein kinase, protein kinase C, and calmodulin-dependent protein kinase II inhibitory peptides, suggesting that staurosporine-sensitive kinase(s) as well as tyrosine kinase(s) are involved in LPS-mediated NF-kappa B activation. In addition, LPS induced the phosphorylation of I kappa B-alpha, starting at 5 min after the stimulation in a cell-free system. Moreover, the phosphorylation was inhibited by herbimycin A and tyrphostin, but not staurosporine, suggesting that these protein kinase inhibitors act at distinct steps of signal transmission. Establishment of ligand-dependent activation of NF-kappa B in a cell-free system will facilitate identification of protein kinase(s) and its substrate(s) involved in LPS-mediated NF-kappa B activation.
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PMID:Establishment of lipopolysaccharide-dependent nuclear factor kappa B activation in a cell-free system. 787 68

The activity of phosphatidylinositol (PI) 3-kinase was examined in murine bone marrow-derived macrophages (BMM) stimulated with the haematopoietic growth factors colony stimulating factor-1 (CSF-1) and granulocyte/macrophage-CSF (GM-CSF). PI 3-kinase was immunoprecipitated from cell lysates using anti-phosphotyrosine antibody or an antibody directed against the 85K subunit of PI 3-kinase, and the activity assayed by the phosphorylation of PI in the presence of [gamma 32P]-ATP. The results demonstrate that CSF-1 increases the activity of PI 3-kinase, as compared to the non-stimulated control, in murine macrophages. Maximum activity was seen after 10 min of stimulation with CSF-1 at 3000-5000 U/ml. The dose-response of CSF-1 is consistent with other biochemical effects of CSF-1 seen in the BMM. GM-CSF also stimulated PI 3-kinase activity although to a lesser extent than CSF-1, correlating well with their degree of mitogenic activity on the BMM. Non-mitogenic macrophage activating agents, such as the phorbol myristate acetate, lipopolysaccharide, concanavalin A and formyl-methionyl-leucyl-phenylalanine, did not significantly increase the PI 3-kinase activity. Furthermore, CSF-1 failed to stimulate PI 3-kinase activity in resident peritoneal macrophages, a population of macrophages with poor proliferative capacity. These results suggest that the PI 3-kinase activity may be involved in the haemopoietic growth factor signalling pathways regulating macrophage growth.
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PMID:Haematopoietic colony stimulating factors CSF-1 and GM-CSF increase phosphatidylinositol 3-kinase activity in murine bone marrow-derived macrophages. 794 7

Human monocytes express the important procoagulant protein, tissue factor (TF), after stimulation by a variety of agents, including bacterial lipopolysaccharide (LPS). Monocyte TF expression may contribute to intravascular coagulation in a number of disease states. The present studies show that monocytic cell TF expression can be inhibited by several agents known to block cellular K+ channels. Exposure of human peripheral blood to 100 ng/mL LPS for 2 hours led to pronounced TF procoagulant activity associated with the mononuclear cell fraction. This was inhibited by 4-aminopyridine (2 mmol/L), tetraethylammonium chloride (10 mmol/L), and apamin (1 mumol/L). In contrast, charybdotoxin (100 nmol/L) was inactive. More detailed studies were carried out in cultured human monocytic tumor THP-1 cells. These cells exhibited low but detectable levels of TF mRNA, measured by reverse transcription and polymerase chain reaction; cell surface procoagulant activity, measured by a plasma clotting assay; and cell homogenate TF antigen, measured by immunoassay. Exposure of THP-1 cells to 1 microgram/mL LPS led to threefold to fivefold increases in all three parameters. Basal and LPS-induced levels of all three parameters were reduced in a dose-dependent manner by 4-aminopyridine (I50, 1 mmol/L) and tetraethylammonium chloride (I50, 20 mmol/L) but not by apamin or charybdotoxin. Expression of TF activity was also inhibited by glibenclamide, an inhibitor of ATP-dependent K+ channels (I50, 25 mumol/L). These results suggest that facilitation of TF synthesis may be an important role for K+ channels in monocytes.
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PMID:K+ channel blockers inhibit tissue factor expression by human monocytic cells. 800 Dec 75

1. Purinoceptor agonist-induced currents in untreated (proliferating) and lipopolysaccharide (LPS; 100 ng ml-1)-treated (non-proliferating) rat microglial cells in culture were recorded by the whole-cell patch-clamp technique. These cells have two preferred resting membrane potentials, one at -35 mV and another one at -70 mV. 2. Most experiments were carried out in non-proliferating cells. ATP, ATP-gamma-S and alpha,beta-MeATP (1-1000 microM in all cases) evoked an inward current at a holding potential of -70 mV, followed, in some experiments, by an outward current. At -70 mV 2-methylthio ATP (1-1000 microM) evoked an inward current, whereas at -35 mV it produced an outward current only. 3. When K+ was replaced in the pipette solution by an equimolar concentration of Cs+ (150 mM), the main outward component of the ATP-gamma-S (10 microM) induced response disappeared. Instead, an inward current was obtained. Replacement of K+ by Cs+ did not affect the inward current evoked by 2-methylthio ATP (300 microM). 4-Aminopyridine (1-10 mM), however, almost abolished this current and unmasked a smaller outward current. 4. The rank order of agonist potency was 2-methylthio ATP > ATP > alpha,beta-MeATP. Adenosine and UTP were inactive. Suramin (300 microM) and reactive blue 2 (50 microM) antagonized the effect of 2-methylthio ATP (300 microM). 5. I-V relations were determined by delivering fast voltage ramps before and during the application of 2-methylthio ATP (300 microM). In the presence of extra- (1 mM) and intracellular (150 mM) Cs+, the 2-methylthio ATP-evoked current crossed the zero current level near 0 mV. When both Cs+ (1 mm) and 4-aminopyridine (1 mM) were present in the bath medium, the intersection of the 2-methylthio ATP current with the zero current level was near - 75 mV.6. 2-Methylthio ATP (1-1I000 MicroM) induced the same inward current both in proliferating and nonproliferating microglia. However, the depolarizing response to 2-methylthio ATP (300 MicroM) was larger and longer-lasting in the proliferating cells. When the free Ca2+ concentration in the pipettes was increased from the standard 0.01 to 1 MicroM, the amplitude and duration of this depolarization was increased in non-proliferating cells. 4-Aminopyridine (1 mM) enhanced the duration, but not the amplitude of responses.7. ATP and its structural analogues stimulate microglial purinoceptors of the P2Y-type. This leads to the opening of non-selective cationic channels and potassium channels. Depending on the resting membrane potential, depolarization or hyperpolarization prevails. Although the inward current produced by 2-methylthio ATP is of similar amplitude in proliferating and non-proliferating microglia, the resulting depolarization is smaller in the latter cell type because of the presence of voltage-sensitive, outwardly rectifying potassium channels.
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PMID:Characterization and possible function of adenosine 5'-triphosphate receptors in activated rat microglia. 801 72

The ability of methotrexate and three lipophilic derivatives (methotrexate-gamma-dimyristoylphosphatidylethanolamine (M gamma D), methotrexate-alpha-dimyristoylphosphatidylethanolamine (M alpha D) and methotrexate-alpha-gamma-di-dimyristoylphosphatidylethanolamine (M alpha gamma D) to modulate mediator release by lipopolysaccharide-stimulated rat peritoneal macrophages was investigated. At nontoxic concentrations, approximately 10 nmol/10(5) cells, M alpha D and M gamma D produced 11.06 +/- 1.0 and 75.6 +/- 5.2%, respectively, inhibition of tumour necrosis factor (TNF) release (mean +/- s.e.m., n = 4). At this same dose M alpha gamma D resulted in 68.8 +/- 2.1% inhibition of TNF but cellular ATP levels were reduced by 80%. The inhibitory activity of all three derivatives was dose-dependent. Non-derivatized methotrexate at a concentration of 25 nmol/10(5) cells had no inhibitory effect upon TNF release (14.7 +/- 0.8%, n = 3). Determination of prostaglandin E2 (PGE2) levels in the same samples demonstrated that all three conjugates were powerful inhibitors of prostaglandin release. At a quarter of the conjugate concentrations described above the monoamides M alpha (3.1 nmol/10(5) cells) and M gamma D (2.5 nmol/10(5) cells) maintained their effects on PGE2 production with 73 +/- 2.3 and 71 +/- 2.0% (n = 4) inhibition, respectively. At this lower concentration, however, the diamide M alpha gamma D (3.1 nmol/10(5) cells) was less effective in reducing the amount of PGE2 released from the macrophages (29 +/- 18%, n = 4). Maximal PGE2 inhibition by each of the conjugates was attained at approximately 5 nmol/10(5) cells. Unconjugated methotrexate (range of 2.5-20 nmol/10(5) cells) did not inhibit the release of PGE2 from lipopolysaccharide-stimulated macrophages.
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PMID:Effect of three lipophilic methotrexate derivatives upon mediator release by lipopolysaccharide-stimulated rat peritoneal macrophages. 805 13


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