Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activities of protein tyrosine kinase and phosphatidylinositol turnover have been found to be associated with cell growth and differentiation. We examined the effects of some inhibitors for these biochemical activities in human myelogenous leukemia cells. Genistein, which is known to inhibit the activities of protein tyrosine kinase, phosphatidylinositol turnover and topoisomerase II, induced nitroblue tetrazolium (NBT) reduction and lysozyme activity in ML-1, HL-60 and U937 cells. Morphological studies showed that genistein-induced differentiation of myeloblastic ML-1 cells into promyelocytes and of promyelocytic HL-60 cells into mature granulocytes. The differentiation-inducing effect of genistein was augmented by addition of 1 alpha,25-dihydroxyvitamin D3 (VD3) or retinoic acid, VD3 being more effective than retinoic acid. Methyl 2,5-dihydroxycinamate, a protein tyrosine kinase inhibitor, had only a weak effect in inducing differentiation of ML-1 cells. On the other hand, psi-tectorigenin was more effective than genistein in inducing the differentiations of ML-1 and HL-60 cells. Psi-tectorigenin is reported to inhibit phosphatidylinositol turnover without inhibiting protein tyrosine kinase. Thus modulation of phosphatidylinositol turnover might be more important than that of protein tyrosine kinase activity for differentiation of some myelogenous leukemia cells.
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PMID:Effects of inhibitors of protein tyrosine kinase activity and/or phosphatidylinositol turnover on differentiation of some human myelomonocytic leukemia cells. 189 51

We have reported previously that phenylarsine oxide (PAO) blocks insulin-stimulated glucose transport in 3T3-L1 adipocytes (Frost, S. C., and Lane, M. D. (1985) J. Biol. Chem. 260, 2646-2652). As shown in the present study, the locus of inhibition is post-receptor. Insulin stimulated the extent of receptor autophosphorylation in solution and in the intact cell by approximately 4-fold. PAO had no effect on this activity. Using reduced and carboxamidomethylated lysozyme as a substrate for the tyrosine-specific receptor, insulin stimulated the rate of receptor kinase-catalyzed substrate phosphorylation by 2-fold; PAO had no effect on this stimulation. However, the insulin-stimulated, serine-specific phosphorylation of two endogenous phosphoproteins (pp24 and pp240) in the intact cell was blocked by 25 microM PAO. These complementary in situ and in vitro studies demonstrate that the inhibition by PAO must be distal to the insulin receptor's protein tyrosine kinase activity.
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PMID:Effect of phenylarsine oxide on insulin-dependent protein phosphorylation and glucose transport in 3T3-L1 adipocytes. 329 62

The objective of this work was to investigate the role of tyrosine kinase in monosodium urate monohydrate (MSUM) and calcium pyrophosphate dihydrate (CPPD) crystal-induced neutrophil activation using the tyrosine kinase inhibitor lavendustin C (LVC). Human neutrophils pretreated with LVC at concentrations between 10 and 150 microM or control neutrophils were stimulated by plasma-coated CPPD or uncoated MSUM, and chemiluminescence, superoxide generation, intracellular calcium concentration, and degranulation (myeloperoxidase and lysozyme release) were monitored with time. LVC strongly inhibited chemiluminescence, superoxide anion generation, myeloperoxidase and lysozyme release, and calcium mobilization. After 1-min crystal-neutrophil incubations, neutrophil cytosolic fractions showed extensive inhibition of tyrosine kinase activity by LVC. We conclude that the inhibition of neutrophil responses to crystal stimulation, by the protein tyrosine kinase inhibitor LVC, provides evidence that supports the involvement of tyrosine kinases in crystal-induced neutrophil activation.
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PMID:Inhibition of crystal-induced neutrophil activation by a protein tyrosine kinase inhibitor. 828 35

Mouse leukemia Mm-A and Mm-S2 cells are subclones of mouse monocytic leukemia Mm cells, Mm-A cells having much higher leukemogenicity than Mm-S2 cells. The growth-inhibitory effects of several protein kinase inhibitors on leukemogenic Mm-A and non-leukemogenic Mm-S2 cells were examined. Most inhibitors of protein serine/threonine kinases inhibited the growth of Mm-A and Mm-S2 cells similarly, but some protein tyrosine kinase inhibitors exhibited differential inhibitory effects on Mm-A and Mm-S2 cells. Genistein inhibited growth of Mm-A cells more effectively than that of Mm-S2 cells, but another inhibitor of tyrosine kinase, herbimycin A, preferentially inhibited growth of non-leukemogenic Mm-S2 cells. Genistein induced or enhanced several differentiation markers of Mm-S2 cells, such as cell spreading, immunophagocytosis, nitroblue tetrazolium (NBT) reduction and lysozyme activity in a dose-dependent manner, but herbimycin A did not. Genistein was cytotoxic to Mm-A cells rather than inducing cell differentiation. Genistein has effects on several other cellular events as well as inhibition of tyrosine kinases. However, it effectively inhibited protein tyrosine phosphorylation in Mm-A cells and its decrease of tyrosine phosphorylation was closely associated with its inhibition of cell growth. Thus, a genistein-sensitive tyrosine kinase(s) may play an important role in the growth and/or survival of leukemogenic Mm-A cells.
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PMID:Genistein exhibits preferential cytotoxicity to a leukemogenic variant but induces differentiation of a non-leukemogenic variant of the mouse monocytic leukemia Mm cell line. 841 97

Protein tyrosine phosphatases were analyzed in oocytes of Ascaris suum. Phosphatases dephosphorylating modified acidic lysozyme were present in high-molecular-weight form (M(r) > 600,000) and as a 50- to 55-kDa protein in the soluble fraction. The low-molecular-weight form of the phosphatase cross-reacted with an antiserum raised against human T-cell protein tyrosine phosphatase and was not distinguishable from the 50- to 55-kDa protein tyrosine phosphatase previously described in the muscular layer of the adult worms (B. Schmid et al. 1996, Molecular and Biochemical Parasitology 77, 183-192). The low-molecular-weight form was also present on immunoblots of high-molecular-weight protein tyrosine phosphatase preparations after denaturing electrophoresis. The same or a similar form of the tyrosine phosphatase was also found in detergent extracts from the pelletal fraction. In addition, another tyrosine phosphatase of 180 kDa molecular mass that dephosphorylated myelin basic protein was also found in extracts from the soluble compartment as well as in detergent extracts from the pelletal fraction. It showed no cross-reactivity with antisera raised against soluble mammalian phosphatases and was resistant to inhibition by vanadate. While the activities of the myelin basic protein-dephosphorylating protein phosphatase remained fairly constant during early development of the oocytes, the activity of the enzyme dephosphorylating modified lysozyme in the pelletal fraction decreased to less than 10% of the initial activity between days 3 and 28 of incubation. Immunocytochemical studies of unfertilized and developing Ascaris eggs revealed association of protein tyrosine kinase and protein tyrosine phosphatase with the egg shell, in addition to their presence in the neighborhood of mitochondria. The amount of enzyme changed with the stage of development. In the larval stage (21 days) protein tyrosine kinase had increased in the chitin layer of the shell and in the nuclei while the relative amount of tyrosine phosphatase decreased in accordance with the biochemical data.
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PMID:Ascaris suum: protein phosphotyrosine phosphatases in oocytes and developing stages. 953 68

In order to explore the depressant action of ambroxol, a bronchial expectorant, on the activated alveolar macrophage responses, its effect on lipopolysaccharide (LPS)- or N-formyl-methionyl-leucyl-phenylalanine (fMLP)- stimulated free radical production and granule enzyme release by rat lung alveolar macrophages was investigated. Ambroxol attenuated the 100 ng/ml LPS- or 1 microM fMLP-stimulated superoxide, H(2)O(2)and nitric oxide production and releases of acid phosphatase and lysozyme by alveolar macrophages. Ambroxol attenuated phorbol myristate acetate-stimulated superoxide and nitric oxide production that was inhibited by 100 nM staurosporine. N,N-dimethylsphingosine (DMS, 4.5 and 9 microM) alone stimulated superoxide production by macrophages, while 45 microM of the compound did not show a stimulatory effect. However, DMS decreased nitric oxide production in a dose-dependent manner. Ambroxol did not alter the DMS effect on free radical production that was affected by 10 microM genistein. A preincubation of macrophages with ambroxol (10 and 100 microM), staurosporine and genistein attenuated the elevation of [Ca(2+)](i)caused by LPS. The results suggest that ambroxol exerts a depressant effect on LPS- or fMLP-stimulated free radical production and granule enzyme release by rat alveolar macrophages, which may be attributed to its inhibitory action on the activation process, protein kinase C, but its action on protein tyrosine kinase is not suggested.
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PMID:Depressant effects of ambroxol on lipopolysaccharide- or fMLP-stimulated free radical production and granule enzyme release by alveolar macrophages. 1054 83

CD45, a transmembrane protein tyrosine phosphatase (PTP), can either positively or negatively regulate Src-family protein tyrosine kinase (PTK) activity in vivo. It is proposed that TCR-initiated signaling requires the segregation of PTP activities from the engaged TCR, based upon the differential membrane compartmentalization on the T cell surface. To test the importance of CD45 exclusion from lipid microdomains for proper TCR signaling, a chimeric molecule was generated by fusing the CD45 cytoplasmic region, which contains the PTP domains, to the amino-terminal 12 amino acids of Lck, which target Lck to lipid microdomains. Using 3A9 T lymphocyte hybridoma (3A9H) cells whose TCR recognizes hen egg-white lysozyme (HEL), Lck-CD45 expression resulted in its targeting to lipid microdomains. The 3A9H cells expressing Lck-CD45 were reduced in their responses to HEL or co-cross-linking of CD3 and CD4, as assessed by IL-2 production and Ca(2+) mobilization. Src-family PTK activity associated with lipid microdomains was also decreased. These results suggest that the segregation of CD45 from proximal TCR signaling components is necessary for TCR signaling and that the targeting of CD45 PTP activity to lipid microdomains on the T cell surface results in decreased sensitivity of TCR-mediated signaling.
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PMID:Targeting of CD45 protein tyrosine phosphatase activity to lipid microdomains on the T cell surface inhibits TCR signaling. 1220 42