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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inhibitors of mast cell tryptase and chymase can be effective as mast cell stabilising compounds. Lactoferrin has been reported to inhibit tryptase activity, but its actions on other serine proteases of mast cells and its potential to alter mast cell function are not known. We have examined the ability of lactoferrin to inhibit mast cell tryptase, chymase and cathepsin G, and investigated its potential to modulate the activation of human mast cells. Enzymatically dispersed cells from human skin, lung and tonsil were challenged with anti-IgE or calcium ionophore A23187, following incubation with recombinant human lactoferrin, and histamine release determined. IgE-dependent histamine release from skin mast cells was inhibited by up to 50% following incubation with lactoferrin (50 or 500 nM). Tonsil mast cells were also stabilised by lactoferrin, but not those from lung. Calcium ionophore A23187-induced histamine release was not altered by lactoferrin. A double-labelling immunocytochemical procedure revealed the presence of lactoferrin in 4-6% of mast cells, and this proportion increased to 40% following incubation with lactoferrin. Lactoferrin did not inhibit cleavage of synthetic substrates by tryptase and chymase directly, though it was able to diminish the ability of heparin to stabilise tryptase. Cathepsin G activity was inhibited by lactoferrin. The ability of lactoferrin to inhibit IgE-dependent activation of human mast cells and modulate protease activity suggests that the release of this neutrophil product may have a role in the downregulation of allergic inflammation.
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PMID:The inhibition of mast cell activation by neutrophil lactoferrin: uptake by mast cells and interaction with tryptase, chymase and cathepsin G. 1262 33

Previous work has shown that endothelial cell (EC)-derived matrix metalloproteinases (MMPs) regulate regression of capillary tubes in vitro in a plasmin- and MMP-1 dependent manner. Here we report that a number of serine proteases can activate MMP-1 and cause capillary tube regression; namely plasma kallikrein, trypsin, neutrophil elastase, cathepsin G, tryptase and chymase. Plasma prekallikrein failed to induce regression without coactivators such as high molecular weight kininogen (HMWK) or coagulation Factor XII. The addition of trypsin, the neutrophil serine proteases (neutrophil elastase and cathepsin G) and the mast cell serine proteases (tryptase and chymase) each caused MMP-1 activation and collagen type I proteolysis, capillary tubular network collapse, regression and EC apoptosis. Capillary tube collapse is accompanied by collagen gel contraction, which is strongly related to the wound contraction that occurs during regression of granulation tissue in vivo. We also report that proMMP-10 protein expression is markedly induced in ECs undergoing capillary tube morphogenesis. Addition of each of the serine proteases described above led to activation of proMMP-10, which also correlated with MMP-1 activation and capillary tube regression. Treatment of ECs with MMP-1 or MMP-10 siRNA markedly delayed capillary tube regression, whereas gelatinase A (MMP-2), gelatinase B (MMP-9) and stromelysin-1 (MMP-3) siRNA-treated cells behaved in a similar manner to controls and regressed normally. Increased expression of MMP-1 or MMP-10 in ECs using recombinant adenoviral delivery markedly accelerated serine protease-induced capillary tube regression. ECs expressing increased levels of MMP-10 activated MMP-1 to a greater degree than control ECs. Thus, MMP-10-induced activation of MMP-1 correlated with tube regression and gel contraction. In summary, our work demonstrates that MMP-1 zymogen activation is mediated by multiple serine proteases and MMP-10, and that these events are central to EC-mediated collagen degradation and capillary tube regression in 3D collagen matrices.
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PMID:MMP-1 activation by serine proteases and MMP-10 induces human capillary tubular network collapse and regression in 3D collagen matrices. 1587 Jan 7

Human mast cells (MC) exhibit two distinct phenotypes based on the protease content of their secretory granules. MC(TC) cells express tryptase, chymase, cathepsin G, and mast cell carboxypeptidase, while MC(T) cells express only tryptase. Both mast cell phenotypes were assessed near regions of osteolysis in uninfected failed joint implants by immunohistochemistry with antibodies to tryptase and chymase, and by in situ hybridization with anti-sense RNA probes for the respective mRNA molecules. Specimens from the interface membrane of 32 aseptically loosened total hip implants were studied, 28 of which had mast cells of the MC(TC) type. Most of these mast cells were aligned along the bone-prosthesis interface adjacent to loosened implants, suggesting involvement in the chronic inflammatory response that leads to bone resorption. Further ultrastructural evidence of mast cells in tissues from failed joint interface membranes was shown by transmission electron microscopy, and detection by staining after magnetic activated cell sorting. The presence of MC at the periprosthetic interface of eroded bone suggests MC degranulation and activity are associated with osteolysis in failed joint prostheses.
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PMID:Simultaneous labeling of mast cell proteases and protease mRNAs at the bone-implant interface of aseptically loosened hip implants. 1597 56

The current study characterizes the cytokine protein (ELISA) and mRNA (gene array and RT-PCR) profiles of skin-derived mast cells cultured under serum-free conditions when activated by cross-linking of Fc epsilonRI. Prior to mast cell activation, mRNA only for TNF-alpha was detected, while after activation mRNA for IL-5, IL-6, IL-13, TNF-alpha, and GM-CSF substantially increased, and for IL-4 it minimally increased. However, at the protein level certain recombinant cytokines, as measured by ELISAs, were degraded by proteases released by these skin-derived mast cells. IL-6 and IL-13 were most susceptible, followed by IL-5 and TNF-alpha; GM-CSF was completely resistant. These observations also held for the endogenous cytokines produced by activated mast cells. By using protease inhibitors, chymase and cathepsin G, not tryptase, were identified in the mast cell releasates as the likely culprits that digest these cytokines. Their cytokine-degrading capabilities were confirmed with purified chymase and cathepsin G. Soy bean trypsin inhibitor, when added to mast cell releasates, prevented the degradation of exogenously added cytokines and, when added to mast cells prior to their activation, prevented degradation of susceptible endogenous cytokines without affecting either degranulation or GM-CSF production. Consequently, substantial levels of IL-5, IL-6, IL-13, TNF-alpha, and GM-CSF were detected 24-48 h after mast cells had been activated, while none were detected 15 min after activation, by which time preformed granule mediators had been released. IL-4 was not detected at any time point. Thus, unless cytokines are protected from degradation by endogenous proteases, cytokine production by human mast cells with chymase and cathepsin G cells may be grossly underestimated.
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PMID:Cytokine production by skin-derived mast cells: endogenous proteases are responsible for degradation of cytokines. 1608 39

The MC(TC) and MCT types of human mast cells initially were recognized on the basis of the protease compositions of their secretory granules, with tryptase, chymase, carboxypeptidase A3, and cathepsin G in the former and only tryptase in the latter. Antibodies against chymase and tryptase traditionally have been used to distinguish these mast cell types from one another. Antitryptase antibodies label all mast cells; antichymase labels only the MC(TC) type. To identify both types in a tissue section, a sequential double-labeling scheme was developed to first stain chymase-positive cells, thereby blocking their recognition by the antitryptase antibody, which will label only the chymase-negative mast cells. In general, these immunocytochemical techniques are more sensitive and specific than classical histochemical techniques for detecting mast cells.
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PMID:Analysis of MC(T) and MC(TC) mast cells in tissue. 1611 Jan 48

Human mast cells contain proteases that are important functional components and serve as markers of mast cell activation or degranulation. Although tryptase is the best recognized mast cell protease, chymase and Cathepsin G also are found in some human mast cells. Methods for measuring the activities of these enzymes using sensitive synthetic peptide thiobenzyl ester substrates are described in this chapter. Using a visible plate reader with kinetic software femtomole quantities of these proteases can be measured. These methods are demonstrated in assays of tryptase and chymase in cell-free extracts of the HMC-1 and 5C6 human mast cell lines, as well as in extracts of cord blood derived mast cells.
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PMID:Human mast cell proteases: activity assays using thiobenzyl ester substrates. 1611 Jan 59

Hematopoietic serine proteases (SPs) are stored in the granules of different leukocytes and these enzymes are important effector molecules in the immune system of mammals. However, very little is known about the presence of these proteins in lower vertebrates. Herein, the primary structures of five novel fish SPs, from the Atlantic cod (Gadus morhua) and the channel catfish (Ictalurus punctatus), are presented. One of the cod SPs is a homologue to human GzmA and K. The other fish SPs identified are termed 'Gzm-like' and are distantly related to a large heterogeneous group of hematopoietic SPs, including most of the T-cell Gzms (B-H), the mast cell chymases, the mast cell/basophil proteases of the mouse mast cell protease-8 subfamily (M8-family) and the neutrophil cathepsin G. Extensive BLAST-searches in genome and expressed sequence tag (EST) databases identified 40 additional teleost SPs related to the mammalian hematopoietic SP family. Subsequent phylogenetical analyses clearly demonstrate that the diversification into different subgroups within the GzmB/chymase/cathepsin G-related family has occurred independently in bony fishes and in mammals. In contrast, our findings suggest that the three subgroups, including (1) GzmK and the potent apoptosis-inducing GzmA, (2) the neutrophil proteases (proteinase 3, N-elastase and azurocidin), and (3) adipsin, have all evolved as distinct groups before the separation of tetrapods from the ray-finned fish approximately 420 million years ago.
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PMID:Granzyme-like sequences in bony fish shed light on the emergence of hematopoietic serine proteases during vertebrate evolution. 1641 8

The acidic granules of natural killer (NK) cells, T cells, mast cells, and neutrophils store large amounts of serine proteases. Functionally, these proteases are involved, e.g., in the induction of apoptosis, the recruitment of inflammatory cells, and the remodeling of extra-cellular matrix. Among the granule proteases are the phylogenetically related mast cell chymases, neutrophil cathepsin G, and T-cell granzymes (Gzm B to H and Gzm N), which share the characteristic absence of a Cys(191)-Cys(220) bridge. The genes of these proteases are clustered in one locus, the mast cell chymase locus, in all previously investigated mammals. In this paper, we present a detailed analysis of the chymase locus in cattle (Bos taurus) and opossum (Monodelphis domestica). The gained information delineates the evolution of the chymase locus over more than 200 million years. Surprisingly, the cattle chymase locus contains two alpha-chymase and two cathepsin G genes where all other studied chymase loci have single genes. Moreover, the cattle locus holds at least four genes for duodenases, which are not found in other chymase loci. Interestingly, duodenases seem to have digestive rather than immune functions. In opossum, on the other hand, only two chymase locus-related genes have been identified. These two genes are not arranged in one locus, but appear to have been separated by a marsupial-specific chromosomal rearrangement. Phylogenetic analyses place one of the opossum genes firmly with mast cell alpha-chymases, which indicates that the alpha-chymase had already evolved as a separate, clearly identifiable gene before the separation of marsupials and placental mammals. In contrast, the second gene in opossum is positioned phylogenetically between granzymes, cathepsin G, and the duodenases. These genes, therefore, probably evolved as separate subfamilies after the separation of placental mammals from marsupials. In platypus, only one chymase locus-like sequence could be identified. This previously published "granzyme" does not cluster clearly with any of the chymase locus gene families, but shares the absence of the Cys(191)-Cys(220) bridge with the other chymase locus proteases. These findings indicate that all chymase locus genes are derived from a single ancestor that was present more than 200 million years ago.
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PMID:Expansion of the mast cell chymase locus over the past 200 million years of mammalian evolution. 1680 45

Serine proteases constitute the major protein granule content of cells of several hematopoietic cell lineages. A subgroup of these proteases, including the mast cell chymases, neutrophil cathepsin G, and T cell granzymes B to F and N, are in all investigated mammals encoded in one locus, the chymase locus. It is interesting to note that this locus has diversified greatly during the last 95 Myr of mammalian evolution. This divergence is exemplified by the presence of Mcpt8-related genes and multiple beta-chymases in the mouse and rat, which lack direct counterparts in primates and in seven functional granzyme genes in the mouse where the human locus has only two. To study the expansion of the locus during rodent evolution and to better understand the evolutionary origin of beta-chymases and the Mcpt8-family, we have performed a detailed analysis of the chymase locus of four mammalian species, i.e., human, dog, mouse, and rat. As a result, we report here a second chymase-like gene in dog, Cma2, which clusters with beta-chymases in phylogenetic analyses. This finding supports a duplication of the common ancestor for alpha- and beta-chymases before the major radiation of placental mammals, and a loss of the ancestral beta-chymase gene sometime during primate evolution. Moreover, we show that in the rat, the Mcpt8-family diversified relatively recently together with sequences related to the beta-chymase Mcpt2. Eight novel genes were identified in the duplication region, four of which are predicted to be functional. Duplications of rat granzyme B- and C-like sequences occurred seemingly independently within a similar time frame, but did not give rise to functional genes. Due to the duplications in rat and deletions in the carnivore/primate lineage, the rat chymase locus is approximately 15 and 9 times larger than its counterparts in dog and human, respectively. These findings illustrate the importance of gene duplications in conferring rapid changes in mammalian genomes.
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PMID:Rapid lineage-specific diversification of the mast cell chymase locus during mammalian evolution. 1680 46

An important feature of chemokines is their ability to bind to the glycosaminoglycan (GAG) side chains of proteoglycans, predominately heparin and heparan sulfate. To date, all chemokines tested bind to immobilized heparin in vitro, as well as cell surface heparan sulfate in vitro and in vivo. These interactions play an important role in modulating the action of chemokines by facilitating the formation of stable chemokine gradients within the vascular endothelium and directing leukocyte migration, by protecting chemokines from proteolysis, by inducing chemokine oligomerization, and by facilitating transcytosis. Despite the importance of eotaxin in eosinophil differentiation and recruitment being well established, little is known about the interaction between eotaxin and GAGs and the functional consequences of such an interaction. Here we report that eotaxin binds selectively to immobilized heparin with high affinity (K(d) = 1.23 x 10(-8) M), but not to heparan sulfate or a range of other GAGs. The interaction of eotaxin with heparin does not promote eotaxin oligomerization but protects eotaxin from proteolysis directly by plasmin and indirectly by cathepsin G and elastase. In vivo, co-administration of eotaxin and heparin is able to significantly enhance eotaxin-mediated eosinophil recruitment in a mouse air-pouch model. Furthermore, when heparin is co-administered with eotaxin at a concentration that does not normally result in eosinophil infiltration, eosinophil recruitment occurs. In contrast, heparin does not enhance eotaxin-mediated eosinophil chemotaxis in vitro, suggesting protease protection or haptotactic gradient formation as the mechanism by which heparin enhances eotaxin action in vivo. These results suggest a role for mast cell-derived heparin in the recruitment of eosinophils, reinforcing Th2 polarization of inflammatory responses.
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PMID:Eotaxin selectively binds heparin. An interaction that protects eotaxin from proteolysis and potentiates chemotactic activity in vivo. 1738 13


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