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

In the murine system, a number of cytokines (including interleukin-3 [IL-3], IL-4, and stem cell factor [SCF]) promote the growth of mast cells (MCs). However, so far little is known about factors controlling differentiation of human MCs. Recent data suggest that human MCs express receptors (R) for SCF. The aim of the present study was to investigate whether recombinant human (rh) SCF induces differentiation of human MCs from their precursor cells. For this purpose, bone marrow (BM; normal donors, n = 6) and peripheral blood (PB; normal donors, n = 11) mononuclear cells (MNC) were cultured in the presence of rhSCF, rhIL-3, rhIL-4, rhIL-9, recombinant human macrophage colony-stimulating factor (rhM-CSF), or control medium in long-term (8 weeks) suspension cultures. After 4 weeks, up to 5% of the MNC (BM and PB) cultured in the presence of rhSCF, but not in the presence of other cytokines, were found to exhibit the characteristics of MCs. These MCs expressed the YB5.B8-reactive domain of the SCF R as well as IgE R, as determined by combined toluidine blue/immunofluorescence staining. Myeloid antigens, likewise expressed on human basophils (ie, CD11b, CDw65, and Bsp-1), could not be detected on these cells. Furthermore, rhSCF, but not rhIL-3, rhIL-4, rhIL-9, or rhM-CSF, induced dose- and time-dependent increases in the formation of cellular tryptase (an MC-specific enzyme) (rhSCF [100 ng/mL], 1,308 +/- 679 ng/mL v control medium, 18 +/- 6 ng/mL tryptase on day 35 of PB cell cultures), as well as an increase in cellular histamine. After 6 to 8 weeks, when other mature hematopoietic cells decreased, MCs still could be detected in culture, with up to 40% of all cells being MCs. To test whether rhSCF also activates tissue MCs, we performed histamine release experiments (dispersed tissue; lung, n = 3; uterus, n = 3). SCF was found to enhance (by up to 3.4-fold) the capacity of the MCs to release histamine upon cross-linkage of IgE R with anti-IgE. Together, these observations suggest that rhSCF induces in vitro differentiation of human MCs from their BM and PB precursor cells in long-term culture and upregulates MC releasability.
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PMID:Induction of differentiation of human mast cells from bone marrow and peripheral blood mononuclear cells by recombinant human stem cell factor/kit-ligand in long-term culture. 138 99

The transition state of acylation step of trypsin catalysis was determined by molecular orbital calculations. The calculations were carried out at the RHF-LCAO-SCF approximation level with double zeta basis set (plus polarization functions). The role of His57 residue in the acylation step of the catalytic reaction of trypsin was analysed from a quantum mechanical point of view. The influences of surrounding residues, such as oxyanion hole and Asp102-, and the electrostatic effect of the other regions of the enzyme were also studied. His57 was proved to capture the proton from Ser195 side chain terminus with its lone pair and to transfer it to substrate with electrostatic assistance of Asp102- and oxyanion hole.
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PMID:Ab initio study on the transition state of acylation step of trypsin catalysis. 216 53

Investigations on the photodynamic action of psoralens with DNA were performed, using experimental techniques of fluorescence lifetime and NMR-CIDNP, as well as SCF-MO and CNDO molecular orbital calculations. It has been shown that the formation of a biradical through the triplet state is the decisive step for psoralen dimer formation, as well as for cyclobutane addition with thymine, while singlet oxygen production is responsible for enzyme inactivation (e.g., lysozyme and trypsin). The molecular orbital calculations, in agreement with experimental results, indicate that the differences in biological effectivity of different psoralens are based on variations in triplet formation probability.
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PMID:Investigations on the mechanism of photodynamic action of different psoralens with DNA. 661 9

In murines, interleukins (IL) 3, 4, 9, and 10, nerve growth factor, and stem cell factor induce or promote growth and differentiation of mast cells (MC). Increased stimulation and synergy was observed when combinations of cytokines were used. In man, no growth factor for human MCs had been identified until recently, when SCF was found to induce in vitro growth and differentiation of human MCs. In the present study, the effects of recombinant human IL-3 and IL-4 on SCF-dependent differentiation of human MCs from their circulating progenitor cells in long-term culture were analyzed. Surprisingly, both IL-3 and IL-4 were found to inhibit SCF-dependent formation of human MCs (SCF, 100 ng/ml: 36.4 +/- 18.7 x 10(3)/ml; SCF + IL-3, 100 U/ml: 23.4 +/- 4.2 x 10(3)/ml; SCF + IL-4, 100 U/ml: 7.4 +/- 4.4 x 10(3)/ml) and synthesis of MC tryptase (SCF, 100 ng/ml: 73.2 +/- 17.6 ng/ml; SCF + IL-3, 100 U/ml: 10.8 +/- 3.1 ng/ml [p < 0.01]; SCF + IL-4, 100 U/ml: 8.1 +/- 1.5 ng/ml, [p = 0.02]). The inhibitory effects of these cytokines on SCF-dependent formation of human MCs were associated with an increase in the number of macrophages (IL-3) or lymphocytes (IL-4) in the same cultures and may be due to competitive recruitment of cells from a pool of multilineage hematopoietic progenitor cells.
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PMID:Inhibition of stem cell factor dependent formation of human mast cells by interleukin-3 and interleukin-4. 752 90

We have isolated and characterized the human cardiac mast cell (CMC) and compared this novel mast cell (MC type with MC obtained from uterus, skin, and lung. Heart tissue was obtained from 14 patients with cardiomyopathy (CMP, heart transplantation). CMC were isolated by enzymatic digestion using collagenase, pronase-E, hyaluronidase, and DNAse. Substantial amounts of CMC (0.5% to 1.5% of isolated cells) were found in the atrial appendages but not in ventricular digests or other sites of the heart (< 0.1%). In situ staining of atrial tissue revealed the presence of CMC in the myocardium (2.16 +/- 0.7 MC/mm2), endocardium (2.24 +/- 0.9 MC/mm2), and epicardium. As assessed by combined toluidine blue/immunofluorescence staining with monoclonal antibodies (MoAbs), isolated CMC expressed surface IgE, the receptor for stem cell factor (c-kit receptor/CD117), the p24 antigen (CD9), the Pgp-1 homing receptor (CD44), the pan leukocyte antigen (CD45), and the ICAM-1 antigen (CD54). CMC were not recognized by MoAbs to lymphocyte function associated antigen 2 (LFA-2; CD2), T-cell receptor (TcR; CD3), T4 antigen (CD4), LFA-1 alpha-chain (CD11a), C3biR alpha-chain (CD11b), CR4 alpha-chain (CD11c), LPS-R related Ag (CD14), 3-FAL/x-hapten (CD15), Fc gamma RIII (CD16), lactosylceramid (CDw17), the B-cell antigen CD19, or CR1 (CD35). In situ expression of leukocyte antigens on CMC was demonstrable by indirect immunoperoxidase staining technique and double-labeling immunohistochemistry. Almost all CMC (90%) reacted with MoAbs against tryptase and chymase and thus were MCTC. Cardiac mast cells were also stained by the heparin-binding dye Berberine sulfate and expressed measurable amounts of histamine (4.6 +/- 1.4 pg per cell). Cross linking of either IgE receptor or SCF receptor (c-kit) on CMC resulted in histamine secretion (non-specific release: < 6% of total histamine, alpha IgE induced: 12% to 52%; SCF-induced release: 9% to 18%), whereas neither substance P (a skin MC agonist) nor the basophil agonist FMLP showed an effect on CMC. Together, the CMC is an MCTC primarily located in the appendage of the atrium. This novel type of MC exhibits surface membrane antigen and functional properties similar to those of lung and uterus MC.
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PMID:The human cardiac mast cell: localization, isolation, phenotype, and functional characterization. 752 50

Human fetal liver cells cultured in the presence of recombinant human stem cell factor (rhuSCF) give rise to highly purified mast cell populations. This study examined the effect of steroid hormones on mast cell differentiation. Dispersed fetal liver cells cultured in the presence of rhuSCF at 50 ng/ml and in the presence or absence of various steroid hormones for 4 weeks, were analysed for the presence of mast cells by metachromatic staining with toluidine blue, by immunohistochemistry with a monoclonal antibody against tryptase, and by immunofluorescent flow cytometry with a monoclonal antibody against Kit. Dexamethasone added to the cultures at day 0 resulted in a dose-dependent inhibition of rhuSCF-induced mast cell differentiation with > 85% inhibition seen at a dose of 10(-6) M. A similar effect was seen with hydrocortisone, but not with oestradiol or progesterone. The addition of dexamethasone resulted in decreased DNA synthesis in 14-day-old cultured cells, as assessed by incorporation of bromodeoxyuridine. Addition of dexamethasone to 3-week-old SCF-dependent fetal liver mast cells had no significant effect on mast cell survival. Removal of dexamethasone after 3 weeks of culture with SCF did not result in mast cell development. Thus, dexamethasone inhibits SCF-induced development of mast cells from fetal liver cells, but shows no appreciable effect on developed mast cells.
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PMID:Dexamethasone inhibits the development of mast cells from dispersed human fetal liver cells cultured in the presence of recombinant human stem cell factor. 753 66

Dienelactone hydrolase (DLH), an enzyme from the beta-ketoadipate pathway, catalyses the hydrolysis of dienelactone to maleylacetate. DLH is unusual because it is the only known naturally occurring enzyme which contains the catalytic triad Cys ... His ... Asp. This triad has previously been created artificially in the mutant serine proteases, thiol subtilisin and thiol trypsin. In both cases the mutant enzymes exhibited activities several orders of magnitude lower than the wild type enzymes; the low reactivity has generally been attributed to the inability of these enzymes to form a catalytically active thiolate anion (Cys- ... His+ ... Asp-). The crystal structure of DLH suggests that the native enzyme exists predominantly in a catalytically inert configuration; the triad cysteine is neutral and points away from the active site binding cleft. However, a crystallographic analysis of C123S DLH complexed with an isostructural inhibitor (dienelactam) indicates that substrate binding induces a prototropic rearrangement of the active site prior to catalysis which results in the formation of a highly nucleophilic thiolate anion. We have performed ab initio SCF/MP2 calculations on a relatively small portion of the active site of DLH to examine the details of this activation process. Our calculations provide supporting evidence that the conformational changes observed in the crystal structure due to inhibitor (or substrate) binding facilitate the formation of a reactive thiolate anion. In particular, substrate binding alters the position of Glu36; the carboxylate side chain of Glu36 is pushed towards C123 enabling it to abstract the thiol proton thus creating a catalytically active thiolate anion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A theoretical study of substrate-induced activation of dienelactone hydrolase. 763 Aug 83

Mast cells (MC3) belong to the hemopoietic system and arise from hemopoietic precursor cells. Human MC progenitors can be detected in the bone marrow as well as in the peripheral blood (pb) and are responsive to the mast cell growth factor SCF, the ligand of the c-kit tyrosine kinase receptor. However, little is known about the subsets of cells that become committed to and differentiate into mature human MC. In this study, the identity of the circulating MC progenitor, previously felt to be a monocyte (Mo) or basophil (Ba), was investigated. For this purpose, CD14+ pb monocytes, CD17+ pb basophils and CD34+ cord blood cells were purified to homogeneity (> 95%) from mononuclear cells (normal adult donors, n = 17, cord blood, n = 2) by counter-flow centrifugation followed by cell sorting with mAb. In the presence of rhSCF, MC developed in long term suspension culture from pure CD34+ cells but not from pure Mo, pure Ba, or Ly (MC-tryptase levels on day 42: CD14+ Mo: 3.7 +/- 0.8 vs CD17+ Ba: 3.2 +/- 0.5 vs Ly: 2.0 +/- 1.5 vs control: 196.5 +/- 92.5 ng/ml, p < 0.001). Depletion of CD34+ cells from MNC resulted in a loss of MC in long term suspension culture, whereas depletion of either Mo, Ba, or Ly did not. In methyl-cellulose cultures in the presence of rhSCF, MC and tryptase could be detected in pure (CFU-mast) and mixed (CFU-myeloid/mast) MC colonies. Together, MC do not originate from circulating Mo, Ba, or Ly. The circulating MC progenitor is a CD34+, c-kit+, Ly-, CD14-, CD17- colony-forming cell. This is the first definitive demonstration that mast cells are replenished directly from early hemopoietic progenitors and thus form a unique cell lineage within the hemopoietic system.
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PMID:Monocytes do not make mast cells when cultured in the presence of SCF. Characterization of the circulating mast cell progenitor as a c-kit+, CD34+, Ly-, CD14-, CD17-, colony-forming cell. 769 41

Mast cell neutral proteases are the most precise markers of heterogeneity among human mast cells. Two types of human mast cells have been recognized. MCTC cells contain tryptase together with chymase, cathepsin-G like protease, and mast cell carboxypeptidase; MCT cells contain tryptase, but lack the other neutral proteases present in MCTC cells. All mast cells develop from hemopoietic stem cells. In vitro procedures for studying mast cell growth have been developed, using the major human mast cell growth factor, stem cell factor (SCF, also called Kit-ligand). Cultures of hemopoietic progenitor cells in the presence of SCF alone result in selective differentiation to mast cells. The same progenitor cells can be induced to differentiate into other lineages when SCF is used with various lineage-specific colony-stimulating factors such as erythropoietin for erythrocytes. Mast cell development from hematopoietic progenitors may represent a "default pathway," occurring optimally in a permissive microenvironment such as skin, bowel, and lung. The presence or absence of certain cytokines in blood and bone marrow may create a non-permissive environment, thus the absence of granulated mast cells in such locations.
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PMID:Human mast cell heterogeneity. 772 Oct 78

It has been reported that the administration of interferon alpha-2b is of potential benefit in the treatment of mastocytosis based on a single patient study (NEJM, Feb 27, 1992, 326(9):619-623). Following this report, we administered interferon alpha-2b at a dose of 4 to 5 million units per square meter of body surface area for at least 12 months to one patient with mastocytosis with an associated hematologic disorder (patient 1), one patient with aggressive systemic mastocytosis (patient 2), and one patient with indolent mastocytosis (patient 3). Patients were monitored with the following clinical and laboratory parameters: serial bone marrow biopsies and aspirates, patient log of histamine release attacks, medication dependency, plasma tryptase levels, serum lactate dehydrogenase (LDH) levels, white blood cell counts and differentials, extent of urticaria pigmentosa lesions, bony involvement, and extent of gastrointestinal involvement and hepatomegaly. We also examined the ability of interferon alpha-2b to inhibit recombinant human stem cell factor (rhSCF)-dependent mast cell proliferation from CD34+ bone marrow-derived cells. All patients demonstrated continued progression of disease in one or more clinical criteria at one year of therapy. Similarly, interferon alpha-2b did not inhibit the culture of mast cells from CD34+ bone marrow-derived cells in the presence of SCF. Thus, in our study of three patients with systemic mastocytosis, treatment with interferon alpha-2b was found to be ineffective in controlling progression of disease.
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PMID:Treatment of three patients with systemic mastocytosis with interferon alpha-2b. 888 64


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