Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined the roles of enzymes from mast cells and from neutrophils in stimulating airway submucosal gland secretion. To avoid effects on surface epithelial cells and goblet cells, we studied a line of cultured bovine tracheal gland serous cells. We discovered that mast cell chymase and neutrophil elastase are the most potent secretagogues of airway submucosal glands described. Mast cell 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 (1,530 +/- 80% over baseline; mean +/- SEM) was approximately 10-fold higher than that evoked by other agonists such as histamine and isoproterenol. Both neutrophil proteases also stimulated secretion in a concentration-dependent fashion with a threshold of greater than 10(-10) M. Elastase was more potent than cathepsin G, causing a maximal secretory response of 1,810 +/- 60% over baseline at 10(-8) M. Secretion by the 3 proteases was noncytotoxic and required catalytically active enzymes. These findings suggest a potential role for neutrophil and mast cell proteases in the pathogenesis of increased and abnormal submucosal gland secretions in diseases associated with inflammation of the airways.
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PMID:Role of enzymes from inflammatory cells on airway submucosal gland secretion. 192 74

Rat mast cell tryptase is located largely if not totally in the cell's secretory granules. When the active site reagent [3H]diisopropyl fluorophosphate was used to label tryptase and chymase simultaneously, the ratio of tryptase:chymase active sites was determined to be 0.05. In comparison to chymase and tryptase in other species and chymase in the rat, rat tryptase is poorly bound to the granule matrix as evidenced by (1) its release parallel to histamine on induction of secretion and (2) its appearance in the supernatant when isolated granules were stripped of their membranes with hypotonic medium. Tryptase on release from the granule is moderately stable at a pH of 5.0 but unstable at pH 7.5, the pH that the enzyme encounters on secretion from the cell. These several properties indicate that the role of rat mast cell tryptase extracellularly is likely to differ greatly from that of chymase.
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PMID:Rat mast cell tryptase. 192 34

A long-term co-culture of mononuclear cells of human umbilical cord blood with mouse embryo-derived 3T3 fibroblasts resulted in the development of human mast cells. These mast cells are morphologically and functionally mature cells, containing 1.4-2.8 micrograms histamine per 10(6) cells and bear approximately 10(5) Fc epsilon RI per cell. The mast cells sensitized with human IgE released histamine upon challenge with anti-IgE. Electron-microscopic analysis of the cells showed that these cells were mature human mast cells, and clearly different from basophilic granulocytes. Most of the mast cells contained some granules with regular crystalline arrays and both tryptase and chymase, resembling human skin mast cells. When mononuclear cells of cord blood were seeded in a millicell insert which was placed on 3T3 fibroblasts monolayer, the number of mast cells developed in the millicell inserts was comparable to those developed in the co-culture of the same cord blood cells with 3T3 fibroblasts. Recent observations that mast cells developed in the presence of concentrated culture supernatants of 3T3 fibroblasts without fibroblasts feeder layers, confirmed that soluble factors released from 3T3 fibroblasts are essential and sufficient for the differentiation of human mast cell progenitors in vitro. Analysis of functional characteristics of cultured mast cells revealed that they respond to anti-IgE, Ca2+ ionophore A23187 and substance P for histamine release, but failed to respond to compound 48/80 and FMLP. Upon anti-IgE challenge, sensitized mast cells generated approximately 80 ng PGD2 per 10(6) cells, and approximately 50 ng of LTC4 per 10(6) cells but no detectable generation of LTB4.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:In vitro development and functions of human mast cells. 193 64

The putative inhibitor domain of Alzheimer's disease amyloid protein precursor was purified from E. coli containing a synthetic gene encoding the Kunitz domain. The purified protein (A4 inhibitor) inhibited the activity of trypsin, forming a 1:1 molar complex with the enzyme. It also strongly inhibited plasmin (Ki = 7.5 x 10(-11) M) from human serum and tryptase (Ki = 2.2 x 10(-10) M) from rat mast cells (tryptase M). In addition, it inhibited rat pancreatic trypsin, alpha-chymotrypsin and kallikrein and human serum kallikrein, but did not inhibit rat chymase, pancreatic elastase, alpha-thrombin, urokinase, papain or cathepsin B.
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PMID:Protease-specificity of Kunitz inhibitor domain of Alzheimer's disease amyloid protein precursor. 196 31

This article reviews the ultrastructural and immunohistochemical features of normal human mast cells (MC) at multiple tissue sites. Current literature indicates that granules containing discrete scrolls (scroll-rich morphology) are frequent in MC from bowel mucosa and lung, locations where the majority of MC show only tryptase immunoreactivity (MCT). In contrast, most MC from skin, breast parenchyma, axillary lymph nodes, and bowel submucosa are characterized by scroll-poor morphology (that is, granules are rimmed by incomplete scrolls forming parallel lamellae and containing central, amorphous granular material or grating/lattice-like structures) and show both tryptase and chymase immunoreactivity (MCTC). MC having granules with both scroll-rich and scroll-poor features can occur in all tissue sites, and an occasional MC, especially in lung and bowel, may show only chymase immunoreactivity (MCC). Chymase immunoreactivity in MC also is closely associated with avidin binding and carboxypeptidase reactivity. We conclude that there is ultrastructural and immunophenotypic diversity among normal human MC, although certain forms predominate in specific tissue environments. In skin, breast tissue, axillary lymph nodes, and bowel submucosa MC tend to have scroll-poor granules and stain for avidin, chymase, tryptase, and carboxypeptidase, whereas, in lung and bowel mucosa MC granules tend to be scroll-rich and stain only for tryptase with currently available reagents.
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PMID:Ultrastructural and immunohistochemical characterization of normal mast cells at multiple body sites. 200 49

An intracellular serine protease zymogen, factor C, is an initiator in the hemolymph coagulation system of horseshoe crab. We purified this zymogen from the hemocytes of the American horseshoe crab, Limulus (L.) polyphemus, the objective being to compare its properties with those of the Japanese horseshoe crab, Tachypleus (T.) tridentatus, factor C. The purified zymogen L.-factor C showed similar properties to those of T.-factor C, in terms of molecular mass (123,000), amino acid composition (1,011 residues), subunit structure (two chains), and antigenicity. Like the zymogen T.-factor C, this zymogen was also activated autocatalytically in the presence of bacterial lipopolysaccharide (LPS) and its synthetic lipid A analogue. A most interesting finding is that both protease zymogens are rapidly activated by alpha-chymotrypsin or rat mast cell chymase, but not by trypsin. The active enzyme factor C showed alpha-thrombin-like specificity toward synthetic tripeptide substrates. This factor C was also strongly inhibited by an alpha-thrombin inhibitor, D-Phe-Pro-Arg-chloromethyl ketone. Thus, the enzymatic properties of factor C are similar to those of mammalian alpha-thrombin. On the other hand, the coagulation cascade system present in the hemocyte lysate was activated when chymotrypsin, free from LPS, was added to the lysate used to detect the endotoxins. The implication of our findings is that the chymotrypsin-catalyzed initiation of the horseshoe crab coagulation system is unique, since all known mammalian coagulation, fibrinolysis and complement systems are initiated by trypsin-like enzymes.
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PMID:Further studies on lipopolysaccharide-sensitive serine protease zymogen (factor C): its isolation from Limulus polyphemus hemocytes and identification as an intracellular zymogen activated by alpha-chymotrypsin, not by trypsin. 201 64

Recent studies have led to a rapid expansion of knowledge concerning the structure and biology of the two major mast cell proteinases, tryptase and chymase. Tryptase is an abundant, trypsin-like enzyme found in the secretory granules of all human lung mast cells. The subunits of the heparin-associated tryptase tetramer appear to be the products of a multigene family whose intron-exon organization is unique and is not closely related to that of other mast cell or leukocyte serine proteinases. In vitro studies suggest that tryptases may participate in lung and airway responses by regulating airway neuropeptide activity, bronchomotor tone, and fibroblast mitogenesis. Mast cell chymases are chymotrypsin-like proteinases related closely to neutrophil cathepsin G and lymphocyte granzymes. The cDNA-derived structures of tryptase and chymase suggest that the two enzymes may differ in modes of activation from proenzyme forms, although the mature enzymes are packaged and released together. Chymase expression appears to be limited to a subset of human lung mast cells most prevalent in the airway submucosa. Possible roles for chymase include inactivation of sensory neuropeptides, regulation of submucosal gland secretion, and potentiation of histamine-induced vascular permeability.
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PMID:The structure and airway biology of mast cell proteinases. 202 78

Two murine mAb were prepared against human mast cell carboxypeptidase (HMC-CP) purified from human skin, and were termed CP1 and CP2, respectively. Double immunohistochemical labeling of Carnoy's-fixed sections of human skin, lung, and gastrointestinal tissue with CP1 and CP2, respectively, and with a murine monoclonal antitryptase antibody demonstrated that HMC-CP was selectively present in a subset of human mast cells. Double labeling experiments with CP1 and CP2, respectively, and a murine anti-chymase mAb demonstrated the presence of HMC-CP in the tryptase-positive, chymase-positive mast cell type (MCTC) only. Immunohistochemical labeling of peripheral blood leukocytes resulted in staining of monocytes with CP2 but not with CP1. In addition to chymase and a cathepsin-G like proteinase, HMC-CP is another neutral protease that is selectively present in the MCTC tryptase-positive, chymase-positive mast cells type of mast cell, thus extending the biochemical definition of human mast cell heterogeneity.
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PMID:Human mast cell carboxypeptidase. Selective localization to MCTC cells. 205 Oct 21

Protease nexin-2 (PN-2) is a protease inhibitor that is synthesized and secreted by a variety of extravascular cells including human fibroblasts. It forms sodium dodecyl sulfate-stable complexes with trypsin, the epidermal growth factor binding protein and the gamma-subunit of nerve growth factor. Recently we reported that PN-2 is the secreted form of the amyloid beta-protein precursor (APP) and is a potent inhibitor of chymotrypsin. Here we describe a two-step procedure to purify PN-2/APP using a monoclonal antibody immunoaffinity column. We also quantitated the protease inhibitory properties of purified PN-2/APP on a number of serine proteases. PN-2/APP was a potent inhibitor of coagulation factor XIa with a Ki = 2.9 x 10(-10). The inhibition of factor XIa by PN-2/APP was augmented by heparin and resulted in a Ki = 5.5 x 10(-11) M. Trypsin and chymotrypsin were also effectively inhibited with a Ki = 4.2 x 10(-10) and 1.6 x 10(-9), respectively. PN-2/APP also inhibited the epidermal growth factor binding protein, the gamma-subunit of nerve growth factor, and chymase and plasmin to a lesser extent. In view of recent findings that PN-2/APP is contained in alpha-granules of platelets and is secreted upon platelet activation, the potent inhibition of factor XIa suggests that PN-2/APP may play a regulatory role in the coagulation pathway at vascular wound sites. In addition, these studies define biochemical activities of PN-2/APP which may be involved in regulating proteases that lead to the generation and deposition of the beta-protein in neurodegenerative lesions associated with Alzheimer's disease and Down's syndrome.
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PMID:Immunopurification and protease inhibitory properties of protease nexin-2/amyloid beta-protein precursor. 211 43

We have previously characterized dog mastocytoma cells propagated in nude mice. We have established two of these lines (C1 and C2) in continuous culture. Freshly disaggregated mastocytoma cells were cultured in Dulbecco's modified Eagle's medium (DME)-H16 mixed with 50% Ham's F12 and supplemented with histidine and 5% allergic dog serum (ADS). Cells were fed every 3 d and passaged weekly. Growth was assessed by cell count. Cell growth was best supported by culture in 5% ADS. C1 cells grow in suspension in ADS and have been passaged 55 times with a doubling time of 37.4 +/- 18.7 h (mean +/- 1 SD; n = 15). C2 cells adhere to tissue culture plastic in ADS and have been passaged 26 times with a doubling time of 49.3 +/- 12.5 h (n = 13). Morphologic and functional characteristics are unchanged from those described in cells propagated in nude mice. Histamine content for C1 is 0.46 +/- 0.18 pg/cell (n = 12) and 0.07 +/- 0.04 pg/cell (n = 6) for C2. Both lines contain the neutral protease tryptase and C2 contains chymase. Calcium ionophore A23187 or ragweed antigen caused concentration-dependent histamine release from both cell lines. C1 and C2 generate prostaglandin D2 in response to A23187. We conclude that dog mastocytoma cells can be established in continuous culture, thus providing a system for studying mast cell biology, including growth and development.
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PMID:Establishment of two dog mastocytoma cell lines in continuous culture. 212 Nov 70


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