Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.31 (beta-glucuronidase)
7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of three platelet-activating factor (PAF) antagonists, WEB 2086, CV 6209 and CV 3988, on neutrophil respiratory burst activity and degranulation in response to PAF was investigated. Both WEB 2086 and CV 6209 significantly inhibited the respiratory burst and degranulation in response to 400 nM PAF in a dose-dependent manner (10(-8)-10(-5) M). Higher concentrations of CV 3988 were required to inhibit these functions (10(-5) M and above). The three antagonists inhibited both the release of beta-glucuronidase (from azurophilic granules) and vitamin B12 binding protein (from specific granules) in response to PAF. Only a small nonsignificant inhibition of neutrophil function occurred in the absence of PAF. There was no loss of viability after incubation with the three antagonists at the concentrations tested. These antagonists will be useful tools to study the involvement of PAF in neutrophil-mediated tissue damage and inflammation.
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PMID:Inhibition of neutrophil respiratory burst and degranulation responses to platelet-activating factor by antagonists WEB 2086, CV 6209 and CV 3988. 158 98

The interaction between vancomycin and teicoplanin (50 and 100 mg/l) on human neutrophils was studied using fMLP- and A23187-induced degranulation of elastase, beta-glucuronidase and vitamin B12-binding-protein. Each of these proteins is a marker of a different population of granules. fMLP-induced degranulation of beta-glucuronidase was significantly impaired by pre-incubating the neutrophils with teicoplanin (without affecting cell viability) although the inhibition was at most 23% at 100 mg/l, a concentration not achieved in the serum of patients after normal doses. Calcium ionophore-induced degranulation of beta-glucuronidase and elastase were slightly impaired (Student two-tailed; P less than 0.1) by both glycopeptides (beta-glucuronidase) and teicoplanin only (elastase). Again, inhibition remained below 25%. Vancomycin and teicoplanin at high concentrations, seldom achieved in patients, can moderately impair neutrophil degranulation.
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PMID:Influence of teicoplanin and vancomycin on degranulation by polymorphonuclear leucocytes stimulated by various agonists: an in-vitro study. 215 Apr 8

We studied the effect of adenosine nucleotides on several aspects of the functional activation of human peripheral blood polymorphonuclear leukocytes (PMN). Radiolabeled ATP bound to PMN in a manner suggesting the existence of specific binding sites because: 1) binding was reversed (92 +/- 6%) by 100-fold excess concentrations of unlabeled ATP but minimally by either ADP (43 +/- 12%) or GTP (37 +/- 8%); and 2) binding saturation was achieved (i.e., specific binding did not increase) above 250 microM ATP. Binding studies revealed that significant ATP hydrolysis occurred, even at low temperatures and in the presence of phosphatase inhibitors. Adenosine nucleotides activated signal transduction mechanisms in PMN because: 1) 1 to 100 microM ATP and 5'-adenylylimidodiphosphate (AMP-PNP) stimulated increased production of 1,2-diacylglycerols; 2) ATP (0.5 to 500 microM) and ADP (0.1 to 10 mM) induced increased insoluble protein kinase (PKC) activity in a dose-dependent manner when used at concentrations greater than 50 microM; 3) ATP (greater than or equal to 50 microM) induced a shift in the solubility of phorbol receptors from mostly soluble (89% in untreated cells) to mostly insoluble (68%), whereas ADP, GTP, and GDP were effective at higher concentrations; and 4) greater than or equal to 50 microM ATP stimulated increased phosphorylation of endogenous PMN proteins. AMP-PNP induced PKC activity and phosphoprotein changes that were qualitatively similar to those observed when PMN were treated with ATP, suggesting that extracellular ATP hydrolysis is not required for signal transduction to activate PKC. Functionally, ATP stimulated the secretion of specific (but not azurophil) granules because vitamin B12-binding protein and low levels of lysozyme, but not beta-glucuronidase, were released; qualitatively similar results were obtained by using AMP-PNP. These results suggest that certain adenosine nucleotides employed at physiologically relevant concentrations stimulate increased 1,2-diacylglycerol production, PKC activity, granule secretion, and endogenous phosphoprotein formation in a manner that is independent of extracellular ATP hydrolysis.
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PMID:Extracellular adenosine nucleotides stimulate protein kinase C activity and human neutrophil activation. 215 72

The protein kinase C inhibitor staurosporine influenced in different ways the functions of human neutrophils. Staurosporine prevented the enhanced protein phosphorylation in phorbol ester- and N-formylmethyionyl-leucylphenylalanine (fMLP)-stimulated cells, and was a powerful inhibitor of the respiratory burst induced by phorbol myristate acetate [IC50 (concentration causing 50% inhibition) 17 nM] and the chemotactic peptides fMLP and C5a (IC50 24 nM). It did not alter, however, the superoxide production by cell-free preparations of NADPH oxidase. Staurosporine had no effect on agonist-dependent changes in cytosolic free Ca2+ and exocytosis of specific and azurophil granules, and showed only a slight inhibition of the release of vitamin B12-binding protein induced by phorbol myristate acetate (decreased by 40% at 200 nM). On the other hand, staurosporine also exhibited neutrophil-activating properties: it induced the release of gelatinase (from secretory vesicles) and vitamin-B12-binding protein (from specific granules). These effects were protracted, concentration-dependent, insensitive to Ca2+ depletion, and strongly enhanced by cytochalasin B. Staurosporine, however, did not induce the release of beta-glucuronidase or elastase (from azurophil granules). Except for the sensitivity to cytochalasin B, these properties suggest a similarity between the exocytosis-inducing actions of staurosporine and PMA. The results obtained with staurosporine provide further evidence that different signal-transduction processes are involved in neutrophil activation, and suggest that protein phosphorylation is required for the induction of the respiratory burst, but not for exocytosis.
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PMID:Staurosporine inhibits the respiratory burst and induces exocytosis in human neutrophils. 255 21

Within 1 min of stimulation of human neutrophils by the chemotactic peptide (N-formyl-L-methionyl-L-leucyl-L-phenylalanine) plus cytochalasin B, myeloperoxidase (together with other granule enzymes) was secreted and detected extracellularly. In contrast with the other granule constituents assayed (vitamin B12-binding protein and beta-glucuronidase), the activity of released myeloperoxidase rapidly decreased, so that, by 10 min after stimulation, only about 5% of the total cellular activity was detected. This inactivation was shown to be dependent on oxidant generation during the respiratory burst, since inactivation was not observed (a) after stimulation of anaerobic suspensions or (b) after release from neutrophils from a patient with chronic granulomatous disease; purified myeloperoxidase was rapidly inactivated after incubation with H2O2, presumably owing to the formation of an inactive enzyme-H2O2 complex. These results show that experiments designed to assess the role of myeloperoxidase in neutrophil functions which utilize assays based on peroxidase activity will grossly underestimate this enzyme if oxidant generation during the respiratory burst has also been activated.
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PMID:Oxidative inactivation of myeloperoxidase released from human neutrophils. 282 34

Myeloperoxidase (MPO)-deficient neutrophils (PMN) released considerably more beta-glucuronidase, lysozyme and vitamin B12-binding activities, when exposed to opsonized zymosan (STZ), than the normal counterpart. Release of the soluble enzyme lactate dehydrogenase was not appreciably changed over the incubation time with particles in either cell type. MPO-deficient PMN and normal PMN ingested STZ particles at a similar rate at early times, but thereafter phagocytosis by MPO-deficient PMN was significantly higher than that by normal PMN. The difference in degranulation between the two cell types greatly exceeded the difference in ingestion and was evident already at early phagocytosis times when no difference in phagocytosis was observed; this suggested that the higher degranulation in MPO-deficient PMN was at least in part independent of the increased ingestion. This was confirmed by experiments with the soluble stimulant N-formyl-L-norleucyl-L-leucyl-phenylalanine (FNLLP). MPO-deficient PMN and normal PMN exhibited a comparable respiratory burst when exposed to FNLLP plus cytochalasin B, but the defective cells released more azurophilic and specific granule markers than normal PMN. These results indicate that MPO-deficient PMN degranulate more than normal PMN and suggest a role for MPO in the regulation of degranulation.
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PMID:Increased degranulation of human myeloperoxidase-deficient polymorphonuclear leucocytes. 298 89

After circulating in the vascular system a short time, polymorphonuclear leukocytes (PMN) migrate to extravascular sites in response to chemotactic stimuli. Prestimulation of PMN in vitro by secretagogues has been shown to increase their number of N-formylmethionylleucylphenylalanine (fmet-leu-phe) and complement component C3bi (CR3) receptors. We investigated whether the same phenomenon occurred in vivo, comparing characteristics of human skin chamber and guinea pig peritoneal exudate and blood PMN. Exudate PMN of both species contained approximately 28% less of the specific granule marker vitamin B12-binding protein (P less than 0.01) but a similar amount of the azurophil granule marker beta-glucuronidase. The total number of fmet-leu-phe receptors was 5.9 times higher in guinea pig exudate than in blood PMN (P less than 0.01) and 2.9 times higher in human exudate than in blood PMN (P less than 0.02). All exudate PMN and most blood PMN preparations showed a high affinity receptor (Kd approximately 2.3 X 10(-8) M) and a low affinity receptor (approximately 1.5 X 10(-7) M). The upregulation of fmet-leu-phe receptors in exudate PMN correlated with an improved responsiveness to fmet-leu-phe induced membrane depolarization, oxidative metabolism, and chemotaxis. In addition, the concentration of fmet-leu-phe that produced a half-maximal response of chemotaxis, superoxide production, and membrane potential depolarization was 10-fold lower in exudate PMN than in blood PMN. Human exudate PMN had a twofold increased C3bi receptor expression compared with blood PMN. Thus, a preferential loss of specific granules is associated with increased number of high and low affinity fmet-leu-phe receptors and increased C3bi receptor expression not only in vitro, but also in vivo. The data indicate that exudation primes PMN for their subsequent responsiveness to fmet-leu-phe, a modification that may be crucial for efficient antimicrobial host defense.
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PMID:Exudation primes human and guinea pig neutrophils for subsequent responsiveness to the chemotactic peptide N-formylmethionylleucylphenylalanine and increases complement component C3bi receptor expression. 300 69

Cytosolic free calcium concentration, [Ca2+]i, and exocytosis of azurophil granules (beta-glucuronidase), specific granules (vitamin B12-binding protein), and secretory vesicles (gelatinase) were measured concomitantly in intact human neutrophils under steady state [Ca2+]i. The cells were loaded with the fluorescent calcium indicator quin2 in the presence or absence of extracellular Ca2+, and steady state [Ca2+]i levels ranging from 20 to greater than 2,000 nM were obtained by adding the Ca2+ ionophore ionomycin at various concentrations of extracellular calcium. The extent of exocytosis from the three granule populations was found to be a function of [Ca2+]i. The minimal [Ca2+]i that caused significant release (threshold [Ca2+]i) was approximately 200-300 nM and was similar for all three compartments. Marked differences, however, were found when the [Ca2+]i for half-maximal exocytosis (EC50) was determined. In the absence of cytochalasin B the EC50 was 1,100 +/- 220 nM and 1,600 +/- 510 nM for specific granules and secretory vesicles, respectively, and approximately 6,000 nM for azurophil granules. Cytochalasin B did not affect the threshold [Ca2+]i but decreased the EC50 and enhanced the rate of exocytosis. In the presence of cytochalasin B the EC50 was approximately 600 nM both for secretory vesicles and specific granules, and approximately 2,600 nM for azurophil granules. The addition of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine dramatically changed the [Ca2+]i dependency of granule secretion: It decreased the threshold [Ca2+]i to less than 20 and less than 50 nM, and the EC50 to 50 and 200 nM for specific and azurophil granules, respectively, and it significantly increased the rate of exocytosis. Thus, the additional signal(s) provided by receptor activation markedly lower(s) the Ca2+ requirement of the exocytotic process. Furthermore, these results indicate that the secretion from three different granule populations within the same cell type are differently modulated by [Ca2+]i.
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PMID:Quantitative analysis of the cytosolic free calcium dependency of exocytosis from three subcellular compartments in intact human neutrophils. 301 10

The properties of platelet-activating factor (PAF-acether) 42-48ulus of exocytosis in human neutrophils have been re-investigated with particular attention to effects on cells that were not pretreated with cytochalasin B. Release of gelatinase, the most sensitive marker of exocytosis, was determined in addition to that of vitamin B-12-binding protein and beta-glucuronidase. Superoxide production was assayed as a measure of the respiratory burst. The effects of PAF-acether were compared to those of leukotriene B4 and N-formylmethionylleucylphenylalanine (fMet-Leu-Phe). Our results show that PAF-acether elicits marked secretion in untreated human neutrophils, and refute the prevalent view that cytochalasin B treatment is required for responsiveness. PAF-acether induced abundant release of gelatinase, increasing on average from 20% at 10 nM to 35% at 1 microM. This release was very rapid, i.e., almost complete after 2 min. fMet-Leu-Phe induced the same maximum response already at 0.1 microM, but release was considerably slower. Leukotriene B4 was less potent with a maximum release of 20%. Exocytosis of gelatinase was always paralleled by liberation of smaller but significant amounts of vitamin B12-binding protein from the specific granules. In contrast to their effect on exocytosis, PAF-acether and leukotriene B4 were very weak stimuli of the respiratory burst when compared with fMet-Leu-Phe.
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PMID:Platelet-activating factor as a stimulus of exocytosis in human neutrophils. 301 43

The authors have previously shown that human neutrophils can be permeabilized with the cholesterol-complexing agent digitonin and that these cells can be induced to secrete granule contents by increasing free Ca2+ concentrations. In the studies reported here, the authors wished to determine whether secretion of granule constituents correlated with the appearance of an immunologic marker for granule membranes on the surface of the permeabilized neutrophils. For this purpose, we used flow cytometry and two fluorometrically identifiable markers, Mo1 (a granule membrane marker) and beta 2-microglobulin (beta 2m) (a plasma membrane marker). It was found that the ratio of Mo1/beta 2m increased for permeabilized neutrophils which were exposed to micromolar concentrations of free Ca2+. This increase in the detectable surface concentration of Mo1 was accompanied by the release of lysozyme, vitamin B12 binding protein, and beta-glucuronidase into the medium. Statistical analysis showed a very strong correlation between granule secretion and the Mo1/beta 2m ratio. These data thus suggest that granule membrane components were being introduced into the plasma membrane during Ca2+-induced granule discharge; this in turn suggests that secretion by permeabilized neutrophils represents true degranulation.
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PMID:Expression of a granule membrane marker on the surface of neutrophils permeabilized with digitonin. Correlations with Ca2+-induced degranulation. 352 11


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