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)

Flow cytometry has been applied to study the persistence and regeneration rate of Epstein-Barr virus (EBV) receptors and other membrane proteins in normal and tumor cells. EBV receptors were detected in a binding assay utilizing fluorescein isothiocyanate-conjugated virions (FITC-EBV). After stripping receptors from the cell surface with trypsin, binding of FITC-EBV was rapidly regenerated in the lymphoma cell line Loukes, reaching 75% of the control levels by 3 h. Fresh human lymphocytes regenerated receptors at a much slower rate, reaching 50% of control levels by 24 h. The regenerating receptors did not reappear simultaneously on all the cells. Subpopulation of new receptor-positive cells increased gradually during the incubation at 37 degrees C. Reappearance of receptors was inhibited in the absence of protein synthesis. Conversely, receptors persisted in the nontrypsinized cells in the absence of protein synthesis. These results show that certain parameters of membrane receptor turnover, such as the change in receptor distribution within a cell population, receptor persistance, and regeneration rate, can be measured at the single-cell level by flow cytometry.
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PMID:Application of flow cytometry to studies on the distribution, persistence, and regeneration rate of Epstein-Barr virus receptors. 609 14

Glucocorticoid receptors of wild-type mouse lymphoma cells and two glucocorticoid resistant variants of nt- and nti phenotypes, respectively, were investigated. Photoaffinity labelling of receptor complexes with a radiolabelled glucocorticoid of high affinity enabled us to analyse crude receptor preparations by SDS gel electrophoresis. Wild-type and nt- receptors yielded radiolabelled polypeptide bands of 98,000 mol. wt while nti receptors had a mol. wt of 42,000. Monoclonal antibodies raised against purified rat liver glucocorticoid receptors reacted with wild-type and nt- receptors but not with nti receptors. Partial proteolysis of wild-type receptors with alpha-chymotrypsin resulted in a fragment of 39,000 mol. wt which contained the steroid binding site but had increased affinity for DNA indistinguishable from nti receptors. Mild proteolysis with trypsin yielded smaller fragments which contained the steroid binding site but did not bind to DNA. A model of the wild-type receptor is discussed.
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PMID:Glucocorticoid receptors of wild-type and variant mouse lymphoma cells. 619 41

A low-Mr freely dialysable endothelial cell-stimulating angiogenesis factor (ESAF) from conditioned medium of a mouse lymphoma cell line has previously been shown to activate latent skin fibroblast procollagenase. Activation comparable with the maximum that can be achieved with trypsin is obtained with chemically undetectable amounts of the factor. We now show that when even smaller amounts of ESAF are used heparin is able to potentiate its action in this system. The relationship between this activity and the mechanism of angiogenesis, which is itself potentiated by heparin, is discussed.
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PMID:Potentiating effect of heparin in the activation of procollagenase by a low-Mr angiogenesis factor. 631 31

T cells from the peripheral blood of a T-cell chronic lymphocytic leukemia (T-CLL) patients, were expanded by culture in the presence of interleukin-2 (IL-2). In contrast to the original leukemic T cells that showed a complete lack of suppressor activity, the proliferating T-CLL cells were extremely potent inhibitors of mitogen, antigen and alloantigen induced lymphoproliferative responses. Compared to the fresh T-CLL cells, the proliferating T-CLL cells showed an enhanced expression of the human T-cell leukemia/lymphoma virus (HTLV) p19 antigen and released type C virus particles into their culture supernatant. A direct involvement of the virus particles in the suppression was however unlikely, since the inhibition was found to be mediated by a soluble inhibitor in the culture supernatant of proliferating T-CLL cells. This inhibitor was very hydrophobic and was inactivated by treatment with trypsin, by heating to 56 degrees C for 2 h and by storage at -70 degrees C for more than 14 weeks. It could be excluded that the suppression of lymphoproliferation was due to competition for IL-2, to toxic effects, to nutrient depletion or to a shift in the kinetics of the target cell responses. Furthermore, it could not be attributed to suppressor inducer activity of the OKT4+ proliferating T-CLL cells, since normal T cells enriched for OKT4+ T cells and depleted for OKT8+ T cells were also inhibited in their proliferation. Since other hemopoietic cell lines, not of OKT4+ T lymphocyte origin, also were suppressed to proliferate, it is concluded that the proliferating T-CLL cells represent a neoplastic T-cell clone that had differentiated into suppressor effector T cells after prolonged culture in the presence of IL-2.
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PMID:Phenotypic and functional characterization of HTLV positive neoplastic T cells cultured with interleukin-2--II. Inhibition of lymphoproliferative responses. 632 61

Cell fusion of mouse lymphoma (L5178Y) was achieved by applying electrical pulses under dielectrophoresis. The presence of dispase, pronase or trypsin facilitated the electric pulse-induced cell fusion. Heat-inactivated pronase was no longer effective. Protease inhibitors (aprotinin and p-tosyl-L-lysine chloromethylketone) suppressed the effect of trypsin. Even in the absence of proteases, the cells pretreated with dispase or pronase underwent fusion with high probabilities, as far as free calcium ions were present in the external solution. It is concluded that facilitation of electrofusion by proteases is due to their proteolytic activities.
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PMID:Facilitation of electrofusion of mouse lymphoma cells by the proteolytic action of proteases. 637 Feb 57

The levels of class II major histocompatibility complex (MHC) antigens (la antigens) on cells of a cultured B lymphoma line (WEHI-279) were significantly increased after 24 hr incubation with medium conditioned by concanavalin A-stimulated mouse or rat spleen cells, or by an azobenzenearsonate- (ABA) specific T cell clone that had been stimulated with ABA-coupled spleen cells or concanavalin A. The levels and properties of the la-inducing activity correlated with those of interferon-gamma (IFN-gamma) measured by inhibition of virus plaque formation. Both the la-inducing activity and the IFN-gamma from the T cell clone had an apparent m.w. of 40,000 determined by gel filtration, were sensitive to treatment with trypsin or exposure to pH 2, but were stable to heat (56 degrees C, 1 hr). The induction of la antigens on WEHI-279 cells was dose-dependent, and the maximum response occurred at a concentration corresponding to 1 to 2 U/ml of antiviral activity. This T cell-derived IFN-gamma-like molecule also increased the expression of cell surface la antigens on another B cell line (WEHI-231), and cell lines of macrophage (J774) and myeloid (WEHI-3B and WEHI-265) origin. Furthermore, in all cases the levels of class I MHC (H-2K or H-2D) antigens were also increased. Similar patterns of induction of Ia and H-2 antigens were obtained with supernatants containing IFN-gamma produced by a monkey cell line (COS) that had been transfected with a plasmid bearing the cloned murine IFN-gamma gene. This activity was sensitive to pH 2 and was not present in the supernatant from COS cells that were not transfected with the murine IFN-gamma gene. These results established that IFN-gamma is the T cell-derived molecule that induces the enhanced expression of Ia and H-2 antigens on B cells and macrophages. A major physiologic role of IFN-gamma may be to regulate immune function through the enhanced expression of MHC antigens.
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PMID:Interferon-gamma induces enhanced expression of Ia and H-2 antigens on B lymphoid, macrophage, and myeloid cell lines. 640 89

We have investigated the importance of glycosylation in determining the function of membrane-bound and secreted immunoglobulin M (IgM). Hickman and Kornfeld (1978) previously observed that glycosylation is required for IgM to be secreted by 104E, a mouse plasma cell tumor. In order to determine whether this requirement is a general one for all forms of IgM, we have used WEHI 279.1, a mouse B lymphoma that synthesizes both the membrane and secreted forms of IgM. In the presence of 5 microgram/ml tunicamycin (Tm), glycosylation of both membrane and secreted IgM is at least 90% inhibited, but total protein synthesis is equivalent in control and Tm-treated cells. Despite the absence of carbohydrate, IgM molecules are properly assembled into monomers for membrane localization. Cells whose surfaces have been stripped of membrane IgM by treatment with anti-mu antibody resynthesize the IgM equally well in the presence or absence of Tm. It is more surprising that the assembly of IgM into pentamers and the secretion of these pentamers into the medium are accomplished at the same rate and to about the same levels in control and Tm-treated WEHI 279.1 cells. This is in sharp contrast to the profound inhibition of IgM secretion observed when the plasmacytoma cell 104E is treated with the same concentration of Tm (5 microgram/ml). Although both WEHI 279.1 and 104E cells secrete IgM, the 2 are models for cells at very different points along the B cell differentiation pathway. The difference in the effect of Tm-treatment on IgM secretion may reflect a cellular change that occurs during this differentiation. The unglycosylated IgM is very sensitive to trypsin digestion, whereas the native forms are not. This suggests that the function of glycosylation may be to stabilize the IgM against proteolysis.
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PMID:Glycosylation is not required for membrane localization or secretion of IgM in a mouse B cell lymphoma. 678

Procedures are described for the isolation of a mast cell growth factor (MCGF) from medium conditioned by mitogen-activated splenic leukocytes (CM). Although optimal conditions for the production of MCGF in CM are identical to those for the production of T cell growth factor (TCGF), MCGF can be dissociated from TCGF after the first stage of purification on a DEAE-cellulose column. MCGF elutes from the column in the breakthrough fraction, whereas TCGF binds avidly to DEAE and is eluted only at high salt concentration. MCGF also differs from TCGF with respect to m.w. (as estimated by Sephadex G-150 chromatography) and sensitivity to trypsin. In addition, MCGF is produced by the murine myelomonocytic leukemia WEHI-3 and the radiation induced thymic lymphoma LBRM-33 cells, whereas TCGF is produced only by the latter in the presence of a mitogen. Another hemopoietically active factor, granulocyte colony-stimulating factor (G-CSF) present in media conditioned by WEHI-3 and LBRM-33 cells, however, shares a number of properties with MCGF. Although studies with purified or partially purified MCGF have thus far failed to reveal a correlation between MCGF and G-CSF, further biochemical analyses are necessary to dissociate MCGF from G-CSF.
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PMID:Long-term in vitro culture of murine mast cells. II. Purification of a mast cell growth factor and its dissociation from TCGF. 678 48

Long-term in vitro growth of murine mast cells was dependent on the presence of a mast cell growth factor (MCGF) present in media conditioned by mitogen-activated splenic leukocytes or by various murine leukemic cell lines. MCGF shared a number of properties with granulocyte colony-stimulating factor (G-CSF). Both factors were present in media conditioned by the myelomonocytic leukemic WEHI-3 and the T cell lymphoma, LBRM-33 cell lines. They were relatively sensitive to trypsin treatment, and were resistant to boiling temperature. NZB mice that failed to respond to WEHI-3-derived G-CSF also failed to respond to MCGF. MCGF differed from G-CSF, however, in sensitivity to neuraminidase and lactoferrin, an inhibitor of macrophage CSF production, suppressed G-CSF production by WEHI-3 cells without affecting MCGF production. Furthermore, peritoneal cells produced G-CSF but not MCGF when stimulated with lipopolysaccharide. In vitro production of MCGF by normal spleen cells required the presence of T lymphocytes and is relatively macrophage-independent. The role of T cells in the maturation and growth of mast cells and the physiologic function of MCGF are discussed.
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PMID:Long-term in vitro culture of murine mast cells. III. Discrimination of mast cells growth factor and granulocyte-CSF. 680 16

Cytogenetic studies from the peripheral blood of a patient with malignant lymphoma and rheumatoid arthritis who was treated with intra-articular gold Au 198 revealed mosaicism with a normal female metaphase and a 43-chromosome metaphase. The abnormal cell line showed six missing normal chromosomes and three morphologically abnormal chromosomes. The trypsin-digested G-banding metaphases showed that the marker chromosomes were an isochromosome of the long arm of chromosome 17, a translocated chromosome that involved the long arm of chromosome 4 and a chromosome 16, and a translocated chromosome that involved the long arm of chromosome 4 and a chromosome 5. It is tempting to conclude that these abnormalities were due to the gold Au 198 treatment, but we cannot exclude other possibilities.
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PMID:Chromosomal abnormalities. Findings in a patient with lymphoma and rheumatoid arthritis treated with intra-articular gold Au 198. 689


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