Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The cell-surface glycoproteins CD44 and CD58 are involved in cell adhesion reactions. In this paper 12 monoclonal antibodies in CD44 and two in CD58 are described. Competitive binding assays using CD44 antibodies identified three distinct epitope groups. Antibodies in Group 1 and, with one exception (BRIC 214), antibodies in group 2, but not antibodies in Group 3, recognized epitopes that are sensitive to reduction and to trypsin or chymotrypsin treatment of intact erythrocytes, and so these epitopes probably reside on the N-terminal disulphide-bonded domain of CD44. Antibodies in CD44 did not inhibit the binding of CD58 antibodies to erythrocytes or vice versa. Quantitative binding studies using radioiodinated IgG measured 1888-5592 copies of CD44 and 1772-3290 copies of CD58 on normal erythrocytes. Similar measurements with radioiodinated Fab fragments gave values of 6508-10,450 (CD44) and 3457-7622 (CD58). Immunocytochemical studies indicated that CD44 is much more widely expressed in non-haemopoietic tissues than CD58. Comparison with previously described CD44 antibodies suggests that antibodies in our Group 1 encompass Hermes 2 and that those in Group 2 encompass Hermes 1. All the CD44 antibodies gave weakened reactions with Lu(a-b-) erythrocytes of the In(Lu) type by one or more methods. BRIC 214 and antibodies in epitope Group 3 were used to demonstrate that CD44 on these variant cells gives membrane-bound trypsin and chymotrypsin cleavage fragments of similar molecular weight to those obtained with normal erythrocytes.
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PMID:New monoclonal antibodies in CD44 and CD58: their use to quantify CD44 and CD58 on normal human erythrocytes and to compare the distribution of CD44 and CD58 in human tissues. 172 Oct 39

B cell differentiation requires adhesion of B cell progenitors to bone marrow (BM) or fetal liver stroma. We show that B lymphoid cells can adhere to the BM stroma cell line CS 1.3, in vitro. Two monoclonal antibodies, SAB-1 and SAB-2, inhibited the adhesion of a B220+ progenitor B cell line but did not interfere with the binding of cytoplasmic mu chain-positive pre-B cells or mature B cells to the BM stromal cell line. Injection of both SAB-1 and SAB-2 antibodies into pregnant mice reduced by 90% the number of B220+n B lineage cells in the livers of their embryos. Livers from such embryos also were virtually devoid of cells able to give rise to B cell colonies in soft agar cultures (CFU-preB). Either antibody separately had no effect. Flow cytometry analysis show that SAB-1 is present on CS 1.3 stroma cells and on a pre-B cell line while SAB-2 is present on pro-B and pre-B cell lines, but not on CS 1.3 stromal cells. SAB-1 and SAB-2 react with different molecules and neither antibody seems to recognize CD44, and adhesion molecule that may also participate in B cell differentiation. Proteinase K and trypsin can digest both SAB-1 and SAB-2 antigens from viable cells suggesting that both are cell surface proteins. We propose that antibodies SAB-1 and SAB-2 probably recognize novel cell-cell adhesion molecules, and that these molecules are involved in the interactions between B cell progenitors and stroma cells.
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PMID:Monoclonal antibodies that block adhesion of B cell progenitors to bone marrow stroma in vitro prevent B cell differentiation in vivo. 188 55

The p85 glycoprotein expressed on a variety of human cell types including astrocytes and lymphocytes has not been associated with the CD44 cluster. The recent demonstration that Hermes, a glycoprotein implicated in the adhesion of lymphocytes to endothelium, belongs to the CD44 cluster raises interesting questions concerning the role of this molecule on astrocytes and on non-lymphoid cells. To obtain confirmation of the identity of p85 glycoprotein and CD44, p85 glycoprotein was purified from B-chronic lymphocytic leukemia cells by affinity to monolonal 50B4-IgG and electrophoretic elution, digested with trypsin or CNBr and fractionated by reversed-phase HPLC. The sequences of three peptides were obtained which could be aligned with the amino acid sequence deduced from the CD44 cDNA at residues 49-54, 59-66 and 309-323. These constitute the first reported peptide sequences for antigens of the CD44 cluster and confirm that p85 glycoprotein is indeed the product of the CD44 gene. Since two different cDNA clones encoding molecules with cytoplasmic tails of 72 and 5 amino acids have been isolated, the isolation of peptide 309-323 confirms the existence of a processed protein with the longer cytoplasmic domain. Using a cDNA probe, we have characterized the expression of CD44 in several normal and malignant cell types. The level of CD44 mRNA was correlated with the surface expression of CD44 antigens (50B4) in several leukemic cell lines, in astrocytoma lines and in normal granulocytes. Negative cells included the Y79 retinoblastoma line, the NALM-6 leukemic line and endothelial cells. Identical mRNA species of 5.0, 2.3 and 1.7 kb were present in all CD44-positive samples, including normal granulocytes, astrocytoma, melanoma and leukemia cell lines and leukemic cells from patients. The highest level of expression of CD44 was observed on astrocytoma lines and on acute lymphoblastic leukemia cells of immature phenotype. The presence of high levels of CD44 on malignant cells could increase the ability of these cells to adhere to matrix proteins and/or to interact with endothelium, thus potentially altering their capacity for invasiveness and metastasis.
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PMID:Confirmation by peptide sequence and co-expression on various cell types of the identity of CD44 and P85 glycoprotein. 223 56

Several studies have suggested that chondrocytes must have the capacity to internalize and degrade extracellular hyaluronan. In the present study we show direct evidence that hyaluronan is, in fact, endocytosed by chondrocytes and that the endocytosis is mediated via cell surface CD44/hyaluronan receptors. Cultures of bovine articular chondrocytes as well as rat chondrosarcoma chondrocytes were incubated with either fluorescein- or 3H-labeled hyaluronan. Intense binding and accumulation of labeled hyaluronan was visualized by fluorescence microscopy or bright-field/dark-field microscopy following autoradiography. Cell surface hyaluronan was removed with either trypsin or Streptomyces hyaluronidase in order to distinguish and quantify intracellular endocytosed hyaluronan. Labeled hyaluronan was visualized within small discrete intracellular vesicles distributed throughout the cytoplasm. Binding and endocytosis of fluorescein- or 3H-labeled hyaluronan was totally blocked by the addition of excess unlabeled hyaluronan or hyaluronan hexasaccharides, competitive inhibitors of hyaluronan/hyaluronan receptor interactions. Binding and endocytosis was also blocked by the addition of anti-CD44 monoclonal antibodies. Characterization of endocytosed 3H-labeled hyaluronan demonstrated that a significant portion of the hyaluronan was degraded by both the bovine articular and rat chondrosarcoma chondrocytes. Interestingly, a higher proportion of bound hyaluronan was internalized by the bovine chondrocytes. Therefore, hyaluronan receptor-mediated endocytosis and degradation of hyaluronan may provide a critical link to the maintenance and homeostasis of cartilage tissue.
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PMID:Internalization of hyaluronan by chondrocytes occurs via receptor-mediated endocytosis. 750 84

Lymphohematopoiesis, cell matrix adhesion, homing of leukocytes, T cell activation, and tumor metastasis are mediated through the CD44 family of cell surface receptors. We have recently shown that anti-CD44 mAb trigger protein tyrosine kinase-dependent activation of T cell effector functions. Here, we show that hyaluronate (HA), a CD44 ligand, in conjunction with CD3/TCR-mediated stimuli, is costimulatory for human peripheral blood T cell proliferation, for IL-2 production by Th clones, and for release of trypsin-like esterase by cytolytic T cell clones. A human T cell line, HUT-78, was found to bind HA and on HA coating it was used as a target for cytolytic T cell clones. After anti-CD3 stimulation, CD3+/CD8+ clones acquire the ability of lysing HA-coated HUT-78 cells more efficiently than the same HA-uncoated targets. Resting peripheral blood T cells and T cell clones do not adhere to HA-coated plates. However, 24-h anti-CD3 mAb stimulation gives them the transient ability to bind HA. HA adhesion of activated T cells and T cell clones, as well as that of T cell lines, is blocked by one anti-CD44 mAb (J-173). Two other anti-CD44 mAbs induce a 10-fold increase in HA adhesiveness of anti-CD3-stimulated peripheral blood T cells. This impressive HA adhesiveness is also readily blocked by J-173 anti-CD44 mAb. These data indicate that 1) HA is costimulatory for human T cell effector functions in conjunction with CD3/TCR-mediated stimuli, 2) the capacity to bind HA is acquired by resting T cells and T cell clones after anti-CD3 stimulation, and 3) HA binding occurs via specific interaction with CD44 molecules expressed on activated T cells.
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PMID:Hyaluronate is costimulatory for human T cell effector functions and binds to CD44 on activated T cells. 751 23

Hyaluronan-binding sites were demonstrated on the cell surface of three malignant mesothelioma cell lines derived from human tumors using either [3H]hyaluronan or fluorescein-tagged hyaluronan. No hyaluronan-binding activity was observed on normal human mesothelial cells. The absence of hyaluronan receptors on normal human mesothelial cells was not due to a down-regulation by endogenously synthesized hyaluronan, since no binding sites appeared when the cells were cultured under conditions known to suppress hyaluronan synthesis (in starvation medium containing either hydrocortisone or n-butyrate) or to degrade endogenously synthesized hyaluronan (in the presence of Streptomyces or testicular hyaluronidase). The binding of [3H]hyaluronan on mesothelioma cells could be partially inhibited by prior incubation of the cells with trypsin, indicating that the hyaluronan-binding site is a protein. The binding sites on human malignant mesothelioma cells were shown to be saturable with about 54,000 hyaluronan molecules (M(r) 1.4 x 10(6)) bound per cell with a Kd of 0.3 x 10(-9) M. The binding was specific for hyaluronan inasmuch as a number of other macromolecules gave negligible inhibition of the binding. High molecular weight preparations of hyaluronan inhibited the binding more effectively than low molecular weight preparations; hyaluronan oligosaccharides down to a length of six monosaccharide units showed competing activity. The hyaluronan receptor appeared to be related to CD44 (a cell surface glycoprotein previously suggested to function as a hyaluronan receptor) since Hermes-1 monoclonal antibodies which inhibit the binding of hyaluronan to CD44 blocked a major part of the binding of hyaluronan to the mesothelioma cells. However, there was no strict correlation between the hyaluronan-binding activity on the mesothelioma cell lines tested and the levels of CD44 molecules on their cell surface, suggesting that only a subfraction of the CD44 molecules bound hyaluronan or that other hyaluronan-binding proteins also exist on those cells. The presence of hyaluronan receptors on mesothelioma cells, but not on their normal counterparts, may be of importance for the migration of the transformed cells in hyaluronan-enriched matrices and for their ability to form metastases.
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PMID:Hyaluronan receptors are expressed on human malignant mesothelioma cells but not on normal mesothelial cells. 751 23

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

A major route for the spread of ovarian cancer is by the attachment of tumour cells to the mesothelium lining in the peritoneal cavity. The expression of various adhesion molecules has been measured on freshly-prepared mesothelial cells, two mesothelial cells lines and 13 established ovarian tumour cell lines. The integrins beta 1 and beta 3, ICAM-1, and CD44 were detected on all mesothelial preparations and on many or all of the tumour lines. VCAM-I was expressed exclusively on the mesothelial cells and Lewis x was expressed on half of the tumour lines. There was low or no expression of sialyl Le(x), sialyl Le(a), integrins alpha 4, beta 1, beta 4, or E and P selectins. Only CD44 expression was significantly affected by trypsin treatment. From the known interactions of adhesion molecules, the results suggest that CD44, and beta 1 and beta 3 integrins may be important in tumour/mesothelial interactions.
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PMID:Expression of cell adhesion molecules on ovarian tumour cell lines and mesothelial cells, in relation to ovarian cancer metastasis. 753 37

We show that antibodies to the CD44 molecule trigger proliferation of human CD3+/CD4+ T-cell clones. Such effect is IL2-dependent, as shown by IL2 production induced by anti-CD44 mAb and by inhibition of cell proliferation in the presence of anti-IL2 antibodies or cyclosporin A (CsA). Moreover, anti-CD44 mAb triggered human cytolytic CD4+ and CD8+ TCR alpha/beta+ clones, and V delta 1 or V delta 2 TCR Y/delta+ clones to lyse Fc-gamma-R+ P815 cells and to release granule trypsin-like esterase enzymes. Anti-CD44 mAb-triggered proliferation and cytotoxicity were blocked by the PTK-inhibitor, genestein. In addition, ligation of the CD44 molecule induced tyrosine phosphorylation of proteins identical, by molecular weight, to those phosphorylated following anti-CD3 mAb-stimulation. Notably, anti-CD44 mAb does not induce tyrosine phosphorylation of a 21 kD protein (the phosphorylated zeta chain of the TcR molecular complex) typically observed upon anti-CD3 mAb stimulation.
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PMID:Ligation of the lymphocyte homing receptor CD44 triggers T-helper and cytolytic functions of human T cells. 776 33

mAb against the lymphocyte homing receptor CD44/Hermes up-regulate the proliferation of human T PBL induced by anti-CD3 or anti-CD2 mAb. Moreover, certain anti-CD44 mAb can activate human resting T cells and mouse cytotoxic T cells in the absence of anti-CD3 or anti-CD2 mAb. Here, we show that anti-CD44 mAb trigger proliferation of human CD3+/CD4+ T cell clones in a fashion similar to that observed with mAb to CD3. Such an effect is IL-2-dependent, as shown by IL-2 production induced by anti-CD44 mAb and by complete inhibition of cell proliferation in the presence of anti-IL-2 antibodies or cyclosporin A. Moreover, anti-CD44 mAb trigger human cytolytic T cell clones to lyse Fc gamma-R+ P815 cells in the absence of additional stimuli. The magnitude of the cytolytic response induced by anti-CD44 mAb is comparable to that observed in the presence of anti-CD3 mAb for both CD4+ and CD8+ TCR-alpha/beta+ clones, and for V delta 1 or V delta 2 TCR-gamma/delta+ clones. By contrast, in CD3-/CD16+ NK cell clones, no cytolytic responses to anti-CD44 mAb could be observed. Granule trypsin-like esterase enzyme (granzyme) release by cytolytic T cell clones is induced by plastic-immobilized anti-CD44 mAb. Anti-CD44 mAb-triggered proliferation ([3H]thymidine incorporation) and cytotoxicity are blocked by the protein tyrosine kinase inhibitor, genestein. In addition, ligation of the CD44 molecule induces tyrosine phosphorylation of proteins identical, by molecular mass, to those phosphorylated after anti-CD3 mAb stimulation. Notably, anti-CD44 mAb does not induce tyrosine phosphorylation of a 21-kDa protein (the phosphorylated zeta-chain of the TCR molecular complex) typically observed upon anti-CD3 mAb stimulation. In conclusion, this study shows that the ligated CD44 molecule provides the necessary stimuli for a variety of T cell-mediated functions triggered via protein tyrosine kinase-dependent signal transduction pathways at least in part similar to those that follow stimulation of the CD3/TCR complex.
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PMID:Antibodies to CD44 trigger effector functions of human T cell clones. 809 50


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