Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The adenosine 5'-triphosphate (ATP)-sensitive K+ channel current was recorded in guinea-pig ventricular myocytes using the patch clamp technique with inside-out patch configuration. Modification of the channel activity by intracellular application of an endoprotease trypsin was studied, and was related to a possible model of regulation of this channel. 2. Maximal ATP-sensitive K+ channel activity was observed immediately upon formation of inside-out patches in the ATP-free internal solution, thereafter activity declined both spontaneously and gradually with time; a phenomenon known as rundown. When trypsin (1 mg/ml) was applied to the intracellular side of the membrane upon formation of inside-out patches, spontaneous run-down did not occur, and this trypsin action was irreversible. Neither trypsin (1 mg/ml) applied with trypsin inhibitor (0.25 mg/ml) nor heat-denatured trypsin (1 mg/ml) could mimic this effect. When trypsin was applied to the patches after run-down, channels were reactivated at approximately 13 min. 3. Treatment with trypsin did not affect unitary current amplitude, channel gating kinetics, or sensitivity to intracellular ATP. 4. Intracellularly applied Ca2+ induced run-down of channel activity in a dose-dependent manner. In membrane patches that were treated with trypsin (1 mg/ml) for 20 min, intracellularly applied Ca2+ up to 1 mM did not induce run-down of channel activity. 5. Intracellular application of an exopeptidase, carboxypeptidase A (1 mg/ml), but not Leu-aminopeptidase (0.5 mg/ml), prevented spontaneous or Ca(2+)-induced run-down of channel activity. 6. As postulated for several other channels, such as Na+ and Ca2+ channels, there may be a possible 'chemical gate' that is responsible for run-down of this channel activity. Application of trypsin might somehow modify this 'chemical gate', resulting in prevention of spontaneous or Ca(2+)-induced run-down. This target site for trypsin may be situated on the carboxy-terminus of the channel proteins, or of associated regulatory units. Because ATP sensitivity remained intact after trypsin treatment, the trypsin-selective site for channel inhibition is not related physically to the ATP binding site.
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PMID:Modification of the adenosine 5'-triphosphate-sensitive K+ channel by trypsin in guinea-pig ventricular myocytes. 841 Jul 13

Among the variety of signals stimulating pancreatic secretion, cholecystokinin (CCK) and related hormones are assumed to be responsible for modulating proteinase output. In some species, intraduodenal tryptic activity has to be abolished to demonstrate feedback-induced CCK release. The aim of this study was to investigate in vivo effects of modest inhibition of intraduodenal proteolytic enzymes on the secretion patterns of pancreatic enzymes and plasma CCK concentrations. Two inhibitors (Kunitz trypsin inhibitor and Bowman-Birk inhibitor) were applied. Intermittent sampling of plasma nd duodenal juice was performed during intraduodenal saline and inhibitor instillations in six healthy volunteers. Enzyme activities and concentrations were determined in the duodenal samples and expressed as percentage of basal values. Instillation of Kunitz trypsin inhibitor caused an increase in trypsin and the pancreatic secretory trypsin inhibitor (PSTI), without changes in plasma CCK. This result demonstrates, for the first time, that pancreatic exocrine secretion of trypsin and chymotrypsin is regulated by different mechanisms. Bowman-Birk inhibitor additionally stimulated the secretion of chymotrypsin and carboxypeptidase A and B and increased plasma CCK. Elastase 1 and amylase secretions were not increased by either instillations. Although the inhibitors have similar in vitro inhibition patterns, their in vivo effects are different. The nonparallel secretion of proteinases (trypsin, chymotrypsin and elastase 1) supports the view of a complex system involved in feedback regulation of human pancreatic exocrine secretion, including signals other than CCK.
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PMID:Proteinase inhibitors induce selective stimulation of human trypsin and chymotrypsin secretion. 859 48

Tryptase is a trypsin-type serine protease that is released from mast cells. Bradykinin (BK) is released directly from kininogens or through activation of either Hageman factor or subsequent plasma prekallikrein. Its nasal administration or inhalation induces allergy-like symptoms. Although elevated levels of tryptase and BK in allergic fluids have been detected, the role of this proteinase and the mechanism of BK production at allergic reaction sites are still unknown. To investigate the pathologic functions of tryptase, the enzyme, purified from human lung, was incubated with normal human plasma, deficient plasmas, kininogens, or prekallikrein. High molecular weight kininogen was then added, and the mixtures were examined for vascular permeability enhancement (VPE) activity, a representative function of bradykinin, using guinea pig skin. Tryptase-treated plasma induced VPE in a dose-dependent manner; activity was lost in the absence of a kininase inhibitor but not an antihistamine drug. Tryptase produced VPE activity from normal or Hageman factor-deficient plasma, but only 30% of this activity was produced from prekallikrein-deficient plasma. Significantly, no activity was obtained from kininogen-deficient plasma. Deficient plasma that were reconstituted with each missing factor resulted in VPE-inducing capacity by tryptase, equivalent to that found with normal plasma. Incubation of tryptase with high or low molecular weight kininogen induced VPE activity in a dose- and incubation time-dependent manner. Prekallikrein incubated with tryptase also generated a soybean trypsin inhibitor-sensitive VPE-inducing activity from high molecular weight kininogen. The loss of tryptase VPE-producing activity as a function of incubation time was found to be a result of spontaneous inactivation of the enzyme and not of the degradation of high molecular weight kininogen by the enzyme. We conclude that tryptase induces VPE by releasing BK, primarily through prekallikrein activation, but also through direct release from kininogens. This indicates that this mast cell-derived proteinase contributes to kinin production in allergic diseases.
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PMID:Induction of vascular permeability enhancement by human tryptase: dependence on activation of prekallikrein and direct release of bradykinin from kininogens. 864 82

Tryptase (EC 3.4.21.59), the major secretory product of human mast cells, has become widely used as a biochemical marker for mast cells and mast cell activation, and is attracting attention as a mediator of allergic disease. However, there is little information available on the properties, or even the presence, of this protease in commonly used species of laboratory animals. We, here, report the demonstration and characterisation of this enzyme in the guinea pig lung. Tryptic activity resistant to alpha 1-proteinase inhibitor and soybean trypsin inhibitor was detected in sections of guinea pig lung tissue with the histochemical substrate Z-Gly-Pro-Arg-MNA. It was localised to mast cells and appeared to be present in all mast cells staining with Alcian Blue. A tryptic protease was purified 2400-fold from whole lung tissue by high salt extraction, cetylpyridinium chloride precipitation, heparin agarose chromatography, and gel filtration. This enzyme was found to be multimeric with a subunit of 38 kDa and a native molecular mass of 860 +/- 100 kDa. Inhibitor studies identified it as a serine protease. Like human tryptase, it was inhibited by leupeptin, benzamidine, and APC 366 (N-(1-hydroxy-2- naphthoyl)-L-arginyl(-L-prolinamide hydrochloride), but not by alpha 1-proteinase inhibitor, soybean trypsin inhibitor, or antithrombin III. Its response to changes in pH and ionic strength was similar to that of human tryptase. Differences between the guinea pig and human enzymes were seen in activity toward a panel fo 10 tryptic p_nitroanilide peptide substrates. Kinetic constants were determined for two of these: with L-Pyr-Pro-Arg-pNA the guinea pig tryptase had a similar Km but a 5-fold lower kcat than human tryptase, and with L-Pyr-Gly-Arg-pNA the guinea pig enzyme had a 10-fold lower Km and a 30% greater kcat than human counterpart. Heparin stabilised guinea pig tryptase, but did not alter its kinetic parameters as it did with human tryptase, decreasing the Km towards both substrates. The presence of a protease with similarities to human tryptase in the mast cells of guinea pigs suggests that this species may be an appropriate model to investigate the actions to tryptase in vivo, provided cognizance is taken of the differences that do exist.
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PMID:Guinea pig lung tryptase. Localisation to mast cells and characterisation of the partially purified enzyme. 869 58

Sheep mast cell proteinase-1 (sMCP-1), a serine proteinase with dual chymase/tryptase activity, is expressed in gastrointestinal mast cells, and released systemically and on to the mucosal surface during gastrointestinal nematode infection. The potential for native plasma proteinase inhibitors to control sMCP-1 activity was investigated. Sheep alpha1-proteinase inhibitor (alpha1PI) inhibited sMCP-1 slowly, with second-order association rate constant (kass) 1. 1x10(3) M-1.s-1, whereas sheep contrapsin inhibited trypsin (kass 2.2x10(6) M-1.s-1) but not sMCP-1. Western-blot analysis and gel filtration showed that when added to serum or plasma, sMCP-1 was partitioned between alpha1PI and alpha2-macroglobulin. The possibility that significant cleavage of plasma proteins could occur before sMCP-1 was inhibited was investigated using gel filtration and SDS/PAGE after adding sMCP-1 to plasma. Cleavage of ovine fibrinogen occurred in the presence of excess alpha1PI and alpha2-macroglobulin, the alpha-chain being cleaved C-terminally and the beta-chain at the putative Lys-27. In addition, sMCP-1 was found to be mitogenic for bovine pulmonary artery fibroblasts, but was not mitogenic in the presence of soya-bean trypsin inhibitor. In terms of fibrinogen cleavage and fibroblast stimulation, sMCP-1 shows functional similarities to mast cell tryptase.
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PMID:Sheep mast cell proteinase-1, a serine proteinase with both tryptase- and chymase-like properties, is inhibited by plasma proteinase inhibitors and is mitogenic for bovine pulmonary artery fibroblasts. 916 5

This study investigated whether short-term exposure to Escherichia coli lipopolysaccharide (LPS) elicits vasomotor dysfunction in skeletal muscle in vivo and, if so, whether perivascular mast cell proteases partly modulate this response. With intravital microscopy, we found that suffusion of E. coli LPS on the in situ hamster spinotrapezius muscle for 60 min elicits immediate vasoconstriction followed by vasodilation. Vasoconstriction is abrogated by SK&F 108566, a selective, nonpeptide angiotensin II (AT II) subtype 1 receptor antagonist, chymostatin and soybean trypsin inhibitor. These compounds also attenuate E. coli LPS-induced vasodilation. By contrast, superoxide dismutase, catalase and indomethacin attenuate only E. coli LPS-induced vasodilation. Endothelin receptor antagonists, lisinopril, leupeptin, Bestatin and DL-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid are ineffective. Histochemical analysis of the spinotrapezius muscle reveals abundant perivascular mast cells with chymostatin-inhibitable chymase-like activity. Pretreatment of hamsters with compound 48/80 for 4 days curtails E. coli LPS-induced vasoconstriction and converts vasodilation to vasoconstriction. On balance, these data indicate that E. coli LPS stimulates perivascular mast cells in the in situ hamster spinotrapezius muscle to release an AT II-producing chymase-like protease(s). AT II thus produced elicits local vasoconstriction and elaborates reactive oxygen species which, in turn, generate vasodilator prostaglandins.
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PMID:Mast cell chymase-like protease(s) modulates Escherichia coli lipopolysaccharide-induced vasomotor dysfunction in skeletal muscle in vivo. 949 78

A chymotrypsin-like proteinase, designated myonase, was successfully purified to homogeneity from X-chromosome linked muscular dystrophic mouse skeletal muscle by affinity chromatography on agarose conjugated with lima bean trypsin inhibitor as ligand. The molecular mass of the purified myonase was determined to be 26 kDa by SDS-PAGE and to be 25,187 Da by mass spectrometry. The native enzyme is a single chain molecule and a monomeric protein without sugar side-chains. The nucleotide sequence of myonase mRNA is similar to mouse mast cell proteinase 4 (MMCP-4) cDNA. This is the first report of a native enzyme whose amino acid sequence closely corresponds to MMCP-4 cDNA. Myonase has chymotrypsin-like activities and hydrolyzes the amide bonds of synthetic substrates having Tyr and Phe residues at the P1 position. Myonase is most active at pH 9 and at high concentration of salts. Myonase preferentially hydrolyzes the Tyr4-Ile5 bond of angiotensin I and the Phe20-Ala21 bond of amyloid beta-protein, and it is less active towards the Phe8-His9 bond of angiotensin I and the Phe4-Ala5 and Tyr10-Glu11 bonds of amyloid beta-protein. Myonase is completely inhibited by such serine proteinase inhibitors as chymostatin, diisopropylfluorophosphate and phenylmethylsulfonyl fluoride, but not by p-tosyl-L-phenylalanine chloromethyl ketone, p-tosyl-L-lysine chloromethyl ketone, pepstatin, E-64, EDTA, and o-phenanthroline. It is also inhibited by lima bean trypsin inhibitor, soy bean trypsin inhibitor, and human plasma alpha1-antichymotrysin. These properties match those of chymase, but unlike chymase, myonase does not interact with heparin in the regulation of its activity. Myonase was immunohistochemically localized in myocytes, but not in mast cells.
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PMID:Purification and characterization of myonase from X-chromosome linked muscular dystrophic mouse skeletal muscle. 953 57

We determined the ability of urinary trypsin inhibitor (UTI), which is a Kunitz-type protease inhibitor present in serum and in urine, to inhibit rat peritoneal mast cell (RPMC) mediator release induced by several stimuli. UTI attenuated the immunoglobulin E-mediated release of both preformed (histamine) and newly formed (leukotriene C4) mediators from RPMCs. Inhibition (21%+/-5%) of the anti-IgE-triggered release of histamine was observed after a 30-minute incubation of RPMCs with UTI (5 micromol/L). To investigate the specificity of the UTI effect, we studied the stimulatory activity of phorbol ester (phorbol 12-myristate 13-acetate (PMA)) or calcium ionophore A23187 in control and UTI-treated mast cells. The efficacy of UTI as an inhibitor was dependent on the nature of the stimulus, because histamine release induced by PMA-mediated or calcium ionophore A23187-mediated processes was not inhibited by UTI. A series of structurally distinct protease inhibitors did not inhibit IgE-induced release of mediators from RPMCs. The Kunitz-type protease inhibitors are important in the regulation of RPMC function. In parallel with the UTI-related decrease in anti-IgE stimulatory activity on mediator release, increased microviscosity of membrane lipids could be observed by two independent experiments on fluorescence polarization with diphenylhexatriene (DPH) and on the fluorescence probe fluorescein isothiocyanate-concanavalin A. UTI reduces mediator release by a mechanism-possibly an interruption of the coupling of receptor and effector systems-because UTI acts as an agent to decrease biologic lipid membrane fluidity.
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PMID:Urinary trypsin inhibitor reduces the release of histamine from rat peritoneal mast cells. 957 92

Mucosal mast cells undergo hyperplasia in a variety of inflammatory bowel diseases including nematode infection in man and animals. The intra-epithelial localization of these cells make their soluble mediators prime candidates for modulators of epithelial function. In particular previous in vivo and ex vivo studies have established a link between the release of the highly soluble mast cell granule chymases and increased mucosal permeability. The hypothesis that the rat mast cell protease, RMCP-II, directly increases permeability to macromolecules via the paracellular route is tested in this study. Monolayers of epithelial cells (Madin-Darby canine kidney cell line) were exposed to varying concentrations of RMCP-II in vitro, in the absence of other cell types or mediators, and the effect on permeability and tight junction associated proteins was investigated. Basolateral, but not apical, exposure of polarized MDCK monolayers on porous supports to RMCP-II led to concentration- (> 100 microg/ml) and time-dependent increases in electrical conductance and permeability to mannitol (MW182) and inulin (MW5000), which was accompanied by decreases in the immunostaining of the tight junction-associated proteins occludin and ZO-1. Furthermore, prolonged exposure to RMCP-II (> 12 hours) resulted in the formation of identifiable gaps separating adjacent epithelial cells, in the absence of evidence of cytotoxicity. Inhibition of RMCP-II with Soya bean trypsin inhibitor completely abrogated the response, demonstrating that proteolysis was required. These data provide direct evidence that the rat mast cell chymase RMCP-II can, in the absence of other inflammatory mediators, increase epithelial permeability via an effect on the paracellular route.
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PMID:The rat mucosal mast cell chymase, RMCP-II, alters epithelial cell monolayer permeability in association with altered distribution of the tight junction proteins ZO-1 and occludin. 962 18

Our aim was to determine if mucosal mast cells could be activated by endogenous CCK and, as a consequence, mediate CCK actions in the small intestine. Rats were prepared for electromyography to record electrical activity in the small intestine. In another group of animals, the duodenum was perfused to measure rat mast cell protease II (RMCP II) as indicative of mast cell degranulation. Endogenous CCK release was induced by administration of soybean trypsin inhibitor (SBTI) in conscious rats or by intraduodenal perfusion of ovalbumin hydrolysate (OVH) in anesthetized rats. CCK concentration was measured by bioassay on pancreatic acini. SBTI in control rats disrupted migrating motor complexes (MMC) for >40 min. In rats treated with the mast cell stabilizer ketotifen, SBTI did not induce any change in the MMC pattern. RMCP II concentration in the duodenal perfusate significantly increased after OVH. Perfusate from ketotifen-treated animals did not show any significant increase in RMCP II values during OVH perfusion, although CCK plasma concentration was not different from the control group. Furthermore, infusion of the CCK-B receptor antagonist L-365,260 significantly blocked the increase of RMCP II concentration after OVH. Our results indicate that mucosal mast cells are degranulated by endogenous CCK release through stimulation of CCK-B receptors. Therefore mucosal mast cells participate in CCK intestinal actions.
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PMID:Mucosal mast cells are involved in CCK disruption of MMC in the rat intestine. 965 85


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