Disease relevance of Mcpt6

• In further experiments using highly purified enzymes, mastocytoma cell chymase activated 92-kD progelatinase in the absence of other enzymes or cofactors; tryptase and dMCP-3, however, had no effect [1].
• Tryptase has potent proinflammatory properties and has been implicated in diverse pathological conditions such as asthma and fibrosis [2].
• Subsequent analysis of a tryptase-specific, phage display peptide library revealed that recombinant mMCP-7 preferentially cleaves an amino acid sequence that is nearly identical to that in the middle of the alpha-chain of rat fibrinogen [3].
• Because enzymatically active mMCP-7 is selectively released into the plasma of V3 mastocytosis mice undergoing passive systemic anaphylaxis, we used this in vivo model system to identify a physiologic substrate of the tryptase [3].
• CONCLUSION: The discovery that the human genome contains a large number of homologous, but distinct, tryptase genes suggests that the individual members of this family of proteases evolved to carry out discrete functions in mast cell-mediated allergic reactions [4].

High impact information on Mcpt6

• Mast cells infiltrate hyperplasias, dysplasias, and invasive fronts of carcinomas, but not the core of solid tumors, where they degranulate in close apposition to capillaries and epithelial basement membranes, releasing mast-cell-specific serine proteases MCP-4 (chymase) and MCP-6 (tryptase) [5].
• Testing of individual mast cell-derived products in this model indicated that tumor necrosis factor was the main mediator of nodal hypertrophy, whereas tryptase and histamine had no effect [6].
• This plasma-localized tryptase was approximately 150 kD in its multimeric state and approximately 32 kD in its monomeric state, possessed an NH2 terminus identical to that of mature mMCP-7, and was not covalently bound to any protease inhibitor [7].
• Inhibitors of tryptase and dog mast cell protease (dMCP)-3, i.e., aprotinin or bis(5-amidino-2-benzimidazolyl) methane (BABIM), did not [1].
• Analysis of mRNA from multiple sclerosis lesions revealed increased amounts of transcripts for several genes encoding molecules traditionally associated with allergic responses, including prostaglandin D synthase, histamine receptor type 1 (H1R), platelet activating factor receptor, Ig Fc epsilon receptor 1 (Fc epsilon RI), and tryptase [8].

Chemical compound and disease context of Mcpt6

• Comparison of the N-terminal 24 residues of mastocytoma tryptase revealed 80% identity with the more limited sequence reported for human lung tryptase, and surprisingly, closer homology to serine proteases of digestion and clotting than to other leukocyte granule proteases sequenced to date, including mast cell chymase [9].
• We examined the temporal distribution and phenotype of mast cells during intestinal schistosomiasis in mice, using antibodies directed against histamine, a general mast cell marker, against mouse mast cell protease-1 (MMCP-1), a mucosal mast cell (MMC) marker, and against tryptase, a predominantly connective tissue mast cell (CTMC) marker [10].
• In dog BR mastocytoma cells incubated with phorbol ester, high steady state levels of alpha-chymase mRNA drop dramatically with little change in tryptase mRNA, whereas dexamethasone decreases expression of both mRNAs [11].
• Human breast cancer is extensively infiltrated by mast cells that contain powerful anticoagulants such as heparin, tryptase and chymase [12].
• CONCLUSIONS: By depleting pre-beta-HDL, mast cell tryptase may impair the initial step of reverse cholesterol transport and will then favor cellular accumulation of cholesterol during atherogenesis [13].

Biological context of Mcpt6

• Both MMCP-6 and MMCP-7 are tryptases, and their coding regions with high homology are closely located on chromosome 17 [14].
• These three motifs were necessary for the 10-fold transactivation ability of the MMCP-6 promoter by +-MITF [15].
• Regulation of mouse mast cell protease 6 gene expression by transcription factor encoded by the mi locus [15].
• Although +-MITF directly bound CANNTG motifs in the promoter region of the MMCP-6 gene and transactivated it, the binding of +-MITF to the CAGTTG motif in the promoter region of the MMCP-5 gene was not detectable [16].
• We reported that expression of the mouse mast cell protease 5 (MMCP-5) and MMCP-6 genes were deficient in cultured mast cells (CMC) derived from mutant mice of mi/mi genotype [17].

Anatomical context of Mcpt6

• Both MMCP-6 and MMCP-7 genes are expressed in normal cultured mast cells (+/+ CMCs) [14].
• The luciferase construct under the control of the MMCP-6 promoter and the cDNA encoding +-MITF or mi-MITF were cotransfected into NIH/ 3T3 fibroblasts [15].
• Mast cell tryptase is stored as an active tetramer in complex with heparin in mast cell secretory granules [18].
• Microphthalmia-associated transcription factor (MITF), a tissue-specific transcription factor predominantly expressed in mast cells, melanocytes, the heart and skeletal muscle, also stimulated the transcription of mMCP-6 [19].
• Cloning of the cDNA and gene of mouse mast cell protease-6. Transcription by progenitor mast cells and mast cells of the connective tissue subclass [20].

Associations of Mcpt6 with chemical compounds

• Because MMCP-5 is a chymase and MMCP-6 a tryptase, there was a possibility that the difference in regulation mechanisms was associated with their different characteristics as proteases [17].
• The minimal heparin oligosaccharide required for binding to mMCP-6 was 8-10 saccharide units [18].
• Analysis of the tryptase family of genes in mice and humans now indicates that a primordial serine protease gene duplicated early and often during the evolution of mammals to generate a panel of homologous tryptases in each species that differ in their tissue expression, substrate specificities, and physical properties [21].
• The dysregulated tryptase in SOCS1-/- BMMCs is unlikely to be mMCP6 or mMCP7, because the enzyme activity was not inhibited by Polybrene but was inhibited by normal mouse plasma [22].
• The proteolytic activity in SOCS1-/- BMMCs was selectively inhibited by phenylmethylsulfonyl fluoride and soybean trypsin inhibitor, suggesting that the protease regulated by SOCS1 is a tryptase [22].

Regulatory relationships of Mcpt6

• On the other hand, dystrophin-positive normal controls injected with 48/80 liberated little CK or tryptase activity [23].
• These results show that c-jun might play a role in regulating the transcription of mMCP-6 gene in mast cells stimulated by SCF [24].
• A second implantation serine proteinase gene (ISP2) was isolated, which encodes a related secreted tryptase expressed specifically within uterine endometrial glands [25].

Other interactions of Mcpt6

• The expression of MMCP-2, MMCP-4, and MMCP-6 was much greater in IC-2G559 and IC-2V814 cells than in the original IC-2 cells [26].
• A possible role of tryptase in angiogenesis in the brain of mdx mouse, a model of Duchenne muscular dystrophy [27].
• Due to its 17-mer hydrophobic domain at its C terminus, mT4 is a membrane-anchored tryptase more analogous to mTMT than the other members of its family [28].
• Genomic blot analysis raised the possibility that uncharacterized tryptase genes reside on chromosome 17 at the complex containing the three genes that encode mouse mast cell protease (mMCP) 6, mMCP-7, and transmembrane tryptase (mTMT) [28].
• Mouse mast cells differentially express at least four chymases (mouse mast cell protease (mMCP) 1, mMCP-2, mMCP-4, and mMCP-5), a tryptase (mMCP-6), and an exopeptidase (mouse mast cell carboxypeptidase A (mMC-CPA)) [29].

Analytical, diagnostic and therapeutic context of Mcpt6

• Gel filtration analyses showed that such short oligosaccharides were unable to generate tryptase tetramers, but instead gave rise to active mMCP-6 monomers [18].
• Electron microscopic examination of cultures supplemented with human rIL-3 and rSCF, but not human rIL-3 alone, revealed that after 3 wk in culture, mast cell granules contained tryptase and exhibited scroll, reticular, and homogeneous patterns as seen previously in CD34+/3T3 fibroblast cocultures [30].
• Heparin affinity chromatography caused a high loss of tryptase and residual protein contamination [31].
• On Western blot analysis and on autoradiography in the presence of the serine protease inhibitor diisopropylfluorophosphate (DFP), only one 28 kD molecule with chymase activity was identified, whereas a broad 32-38 kD band of tryptase monomers was noted [31].
• By northern blot analysis with oligonucleotide probes specific for the alpha and beta tryptases both cell lines were found to express only one type of tryptase [32].

References