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)

Tryptase and chymase were localized in human mast cells by immunoelectron microscopy, enabling the T (tryptase positive, chymase negative) and TC (tryptase positive, chymase positive) types of mast cells to be identified and ultrastructurally characterized. A double immunogold staining procedure was performed on samples of human skin, small intestine, and lung with rabbit polyclonal IgG anti-chymase and mouse monoclonal IgG anti-tryptase primary antibodies and gold-conjugated secondary antibodies. Approximately 225 mast cells were examined in this fashion; comparable sections from 170 of these mast cells along with approximately 200 additional mast cells also were examined using techniques optimized for ultrastructural detail. Each secretory granule of TC mast cells contained both tryptase and chymase; secretory granules of T mast cells stained strongly positive for tryptase alone. Extremely small amounts of chymase appeared to be present in an occasional T mast cell granule. Staining for the neutral proteases was more intense over electron-dense regions of the granules, particularly noticeable over the characteristic discrete scrolls of T mast cells. T and TC mast cells each had large numbers of cytoplasmic granules, nuclei with peripherally condensed chromatin and low nuclear/cytoplasmic ratios, indicating maturity of both cell types. TC mast cell granules generally were more uniformly electron dense, larger and more numerous than T mast cell granules, which were more variable in shape. Compact solid-core scrolls, peripheral parallel lamellae and amorphous electron-dense material were found in granules of both cell types. Only TC mast cells had granules with grating and lattice substructures; only T mast cells had granules containing discrete scrolls. Less commonly, T mast cells were detected containing granules with a characteristic beaded or particulate ultrastructure. The ultrastructural features noted above were observed in T and TC mast cells regardless of the tissue in which they were examined and thereby permit T and TC mast cells to be distinguished by ultrastructure alone.
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PMID:Ultrastructural analysis of human T and TC mast cells identified by immunoelectron microscopy. 245 49

The serine proteases tryptase and chymase are present in human pulmonary mast cells. About 10-100 times more tryptase than chymase is found in these cells. However, a clear physiological role for both enzymes remains to be elucidated; angiotensin processing has been proposed as one possible function of chymase. A dose-dependent inhibition of A23187-induced histamine release from dispersed human lung mast cells was observed after pretreatment with the serine protease inhibitor diisopropylfluorophosphate (DFP) or the chymotrypsin-like enzyme inhibitor N-tosyl-L-phenylalanine chloromethylketone (TPCK) but not with the trypsin-like enzyme inhibitor N-tosyl-L-lysine chloromethylketone (TLCK). These results indicate that a chymase is probably an important factor in a late phase of human lung mast cell activation.
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PMID:The effect of serine esterase inhibitors on ionophore-induced histamine release from human pulmonary mast cells. 245 88

The release of histamine from rat mast cells induced by anti-immunoglobulin E (IgE) was markedly inhibited by Bowman-Birk soybean protease inhibitor (BBI) and anti-chymase F(ab')2 fragments which inhibit chymase activity [Kido, H., et al. (1985) Biochem. Int. 10, 863-871, and Fukusen, et al. (1987) Biochem. Med. Metab. Biol. 38, 165-169]. When radioiodinated anti-chymase F(ab')2 fragments or BBI were incubated with mast cells at 37 degrees C, they were subsequently recovered in the fractions of mast cell granules and of plasma membranes by Percoll density gradient centrifugation. However, when they were incubated with mast cells at 0 degrees C, they had no effect on histamine release and were subsequently recovered only in the plasma membrane fraction. Histamine release from mast cells was suppressed dose-dependently by the antibodies or BBI accumulated in mast cell granules at 37 degrees C. These results suggest that the antibodies and BBI are incorporated into mast cell granules and inhibit chymase activity, resulting in inhibition of histamine release.
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PMID:Antibodies and inhibitor of chymase are incorporated into mast cell granules and inhibit histamine release. 246 36

Serine proteases in mast cell granules, such as chymase, atypical chymase, and tryptase, which are major proteins in the granules, may play important roles in the process of immunoglobulin E (IgE)-mediated degranulation and in pathobiological alterations in tissues. Indeed, inhibitors of chymase, substrate analogs, and antichymase F(ab')2, but not inhibitors of tryptase, markedly inhibited histamine release induced by IgE-receptor bridging but not that induced by Ca ionophore. In contrast, inhibitors of metalloprotease inhibited histamine release induced not only by IgE-receptor bridging but also by Ca ionophore. These results suggest that chymase and metalloprotease are involved at different steps in the process of degranulation. The extents of inhibition of histamine release were closely correlated with the amounts of the inhibitors of chymase accumulated in the granules. After degranulation, the released proteases may in part contribute to pathobiological alterations in allergic disorders through generations of C3a anaphylatoxin and thrombin by human and rat tryptase, respectively, and those of angiotensin II and a chemotactic factor of neutrophils by human and rat chymase, respectively. Moreover, chymase and atypical chymase from rat were shown to destroy type IV collagen, and human tryptase was found to hydrolyze various plasma proteins, such as fibrinogen and high-molecular-weight kininogen. The biological activities of tryptase and chymase from rat may be regulated by their dissociation from and association with trypstatin, an endogenous inhibitor of these proteases.
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PMID:Biological functions of serine proteases in mast cells in allergic inflammation. 246 15

Human pulmonary mast cells contain the serine proteases tryptase and chymase. Chymase is present in much smaller quantities than tryptase. The definite physiological role of both enzymes remains to be elucidated, angiotensin processing has been proposed as one possible function of chymase. A dose-dependent inhibition of A 23187-induced histamine release from dispersed human lung mast cells was observed after pretreatment with diisopropylfluorophosphate (DFP) or 1-1-tosyamide-2-phenylethyl chloromethyl ketone (TPCK) but not with N-2-p-tosyl-1-lysine chloromethyl ketone (TLCK). In contrast, no inhibition was observed under the same conditions with isolated rat peritoneal mast cells. These results indicate that a chymase is probably an important factor in a late phase of human lung mast cell activation. Current work focuses on the isolation of human lung chymase to further investigate this topic.
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PMID:The role of chymase in ionophore-induced histamine release from human pulmonary mast cells. 246 1

Populations of mature, long-lived, nondividing mast cells develop on embryonic fibroblast monolayers after 1 mo growth of lymph node cells taken from mice immunized with horse serum. Total mast cell degranulation with 80-90% histamine release has been obtained by monoclonal anti-2,4-dinitrophenol (anti-DNP) IgE and the antigen. This degranulation process was studied by time-lapse cinematography and scanning electron microscopy. Excitation of the mast cells began as early as 10 s after addition of the antigen and lasted for about 15 s. Consequently, the fibroblast cytoplasm was displaced by short 5-10 s movements. Before degranulation, due to an extracellular film that coated the cells and the extracellular fibers, the monolayer appeared as a continuous, uninterrupted layer. After degranulation and fibroblast cytoplasm displacement, the fibrous network was exposed. Several inhibitors and antagonists of mast cell mediators were introduced to the cultures prior to addition of the antigen. So far, only with soybean trypsin inhibitor was the cytoplasm dislocation inhibited. Histamine H1 and H2 and serotonin receptor antagonists, as well as indomethacin, cortisol, aprotinin, and phenylmethylsulfonyl fluoride, did not inhibit. These results suggest that chymase, which constitutes the greater part of the mast cell granule protein, is the causative agent.
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PMID:Structural alterations in fibroblast monolayers caused by mast cell degranulation. 247 Aug 46

Submucosal glands are the major sources of airway secretions in most mammals. Mast cells are abundant in the environment of airway submucosal glands and are rich sources of secreted proteases. To investigate the hypothesis that mast cell proteases stimulate airway gland secretion, we studied the ability of the two major mast cell granule proteases, chymase and tryptase, to cause secretion of 35S-labeled macromolecules from a line of cultured bovine airway gland serous cells. Mast cell chymase and tryptase were purified from dog mastocytoma cells. Chymase markedly stimulated serous cell secretion in a concentration-dependent fashion with a threshold of 10(-10) M, whereas tryptase had no effect. The response to 10(-8) M chymase (1530 +/- 80% over base line) was approximately 10-fold higher than that evoked by other agonists such as histamine and isoproterenol. The predominant 35S-labeled macromolecule released by chymase was chondroitin sulfate proteoglycan, the glycoconjugate present in serous cell secretory granules. The response to chymase was non-cytotoxic and was blocked by active site inhibitors of chymase (soybean trypsin inhibitor and chymostatin) and by inhibitors of cellular energy metabolism (azide,2,4-dinitrophenol, dicumarol). Supernatant obtained by degranulation of mastocytoma cells caused a secretory response of comparable magnitude to that caused by chymase. These findings demonstrate that chymase, but not tryptase, is a potent secretagogue for airway gland serous cells, and they suggest a possible role for chymase-containing mast cells in the pathogenesis of airway hypersecretion.
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PMID:Mast cell chymase. A potent secretagogue for airway gland serous cells. 249 59

Recent evidence suggests that nonadrenergic airway relaxation may be controlled by vasoactive intestinal peptide (VIP). The magnitude and duration of smooth muscle relaxation in response to VIP may be influenced by rates of peptide degradation after release from efferent peptidergic neurons. To explore the potential role of mast cell mediators in modulating neural control of airway tone, we studied the effect of the mast cell proteases tryptase and chymase on airway smooth muscle relaxation induced by VIP in ferret airway. Tracheal rings precontracted by serotonin (10(-6) M) in a muscle bath were relaxed by VIP (10(-7) M). We found that protease-rich supernatant obtained by degranulation of dog mastocytoma cells reversed VIP-induced relaxation, as did highly purified tryptase and chymase incubated with the tracheal rings. Either enzyme completely reversed the effect of VIP, but tryptase was more potent than chymase, paralleling previous test tube observations on the relative rates of VIP cleavage by the two enzymes. Inhibitors of mast cell tryptase and chymase preincubated with the supernatant or with the purified proteases prevented reversal of VIP-induced relaxation. Mast cell proteases did not reverse the tracheal relaxation caused by the nonpeptide adrenergic agonist isoproterenol. These findings show that mast cell proteases tryptase and chymase counteract the smooth muscle relaxant effects of VIP in ferret trachea and suggest a potential role for the mast cell proteases in the modulation of nonadrenergic neural control of airway tone by VIP.
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PMID:Mast cell tryptase and chymase reverse airway smooth muscle relaxation induced by vasoactive intestinal peptide in the ferret. 249 55

The ability of plasma proteinase inhibitors to inactivate human chymase, a chymotrypsin-like proteinase stored within mast cell secretory granules, was investigated. Incubation with plasma resulted in over 80% inhibition of chymase hydrolytic activity for small substrates, suggesting that inhibitors other than alpha 2-macroglobulin were primarily responsible for chymase inactivation. Depletion of specific inhibitors from plasma by immunoadsorption using antisera against individual inhibitors established that alpha 1-antichymotrypsin (alpha 1-AC) and alpha 1-proteinase inhibitor (alpha 1-PI) were responsible for the inactivation. Characterization of the reaction between chymase and each inhibitor demonstrated in both cases the presence of two concurrent reactions proceeding at fixed relative rates. One reaction, which led to inhibitor inactivation, was about 3.5 and 4.0-fold faster than the other, which led to chymase inactivation. This was demonstrated in linear titrations of proteinase activity which exhibited endpoint stoichiometries of 4.5 (alpha 1-AC) and 5.0 (alpha 1-PI) instead of unity, and SDS gels of reaction products which exhibited a banding pattern indicative of both an SDS-stable proteinase-inhibitor complex and two lower Mr inhibitor degradation products which appear to have formed by hydrolysis within the reactive loop of each inhibitor. At inhibitor concentrations approaching those in plasma where inhibitor to chymase concentration ratios were in far excess of 4.5 and 5.0, the rate of chymase inactivation by both serpin inhibitors appeared to follow pseudo-first order kinetics. The "apparent" second order rate constants of inactivation determined from these data were about 3000-fold lower than the rate constants reported for human neutrophil cathepsin G and elastase with alpha 1-AC and alpha 1-PI, respectively. This suggests that chymase would be inhibited about 650-fold more slowly than these proteinases when released into plasma. These studies demonstrate that although chymase is inactivated by serpin inhibitors of plasma, both inhibitors are better substrates for the proteinase than they are inhibitors. This finding along with the slow rates of inactivation indicates that regulation of human chymase activity may not be a primary function of plasma.
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PMID:Reaction of human skin chymotrypsin-like proteinase chymase with plasma proteinase inhibitors. 259 76

Mast cells at immature stages of development were identified in human tissues by electron microscopic techniques. General morphologic criteria of immaturity (such as a high apparent nuclear:cytoplasmic ratio and small cell size), the presence of few granules (those present being smaller than those in mature mast cells) and a lack of features of mast cell activation were used together to determine the level of maturity. Mast cells were identified as being of the T or TC type by immunogold staining with polyclonal rabbit IgG anti-chymase and murine monoclonal anti-tryptase primary antibodies and the appropriate gold-labeled secondary antibodies. Only those cells with tryptase-positive granules were recognized as mast cells. Immature T mast cell granules contained the same characteristic discrete scrolls found in their mature counterparts and all stained positive for tryptase. The presence of trace amounts of chymase in a minority of these granules, as in mature T mast cells, could not be ruled out. The majority of granules in immature TC mast cells had one or more amorphous electron-dense cores rather than the grating and lattice substructures characteristic of granules in mature TC mast cells. Secretory granules in immature TC mast cells stained positively for tryptase and chymase. Occasional immature TC mast cells contained a complete granule or a portion of a granule with the substructure characteristic of mature TC mast cells, favoring the concept that these TC mast cell forms are developmentally related. Essentially all mast cells in foreskin of newborns appeared immature, whereas 10, 5, 10, and 15% of the mast cells in adult lung, foreskin, bowel mucosa and bowel submucosa, respectively, appeared immature. The distribution of T and TC types of immature mast cells seemed to parallel that of the mature mast cell types. These compositional and ultrastructural differences between immature T and TC types of mast cells suggest that from the time granule formation begins, and possibly before this time, each type of human mast cell follows a distinct developmental pathway.
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PMID:Ultrastructural analysis of maturing human T and TC mast cells in situ. 264 87


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