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:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lucifer yellow (LY) accumulation was used to measure macrophage pinocytosis. The hematopoietic growth factors, macrophage colony-stimulating factor (CSF-1), granulocyte-macrophage CSF (GM-CSF), and interleukin 3, and the macrophage activators, lipopolysaccharide and zymosan, all stimulated LY uptake in both murine bone marrow-derived macrophages (BMMs) and resident peritoneal macrophages (RPMs) without affecting LY efflux. The stimulation of pinocytosis in the poorly cycling RPMs and in BMMs by nonmitogens dissociates stimulation of pinocytosis from subsequent DNA synthesis. Regulation of pinocytosis in BMMs appears to be independent of that of urokinase-type plasminogen activator expression. The increases in CSF-mediated BMM pinocytosis were not inhibited by pertussis toxin, by elevations in intracellular cAMP, or by glucocorticoids and were only partially inhibited by inhibitors of Na+/H+ antiport and Na+/K(+)-ATPase activities. Protein kinase C activation could be involved in regulating BMM pinocytosis because phorbol myristate acetate, oleoylacyglycerol, and exogenously added phospholipase C can all stimulate it. Ca2+ ionophores were inactive, whereas the Na+/H+ ionophore monensin potently inhibited BMM pinocytosis.
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PMID:Regulation of pinocytosis in murine macrophages by colony-stimulating factors and other agents. 131 79

Steel factor (SF), the ligand for the proto-oncogene c-kit, acts synergistically with GM-CSF or IL-3 to support the growth of normal human hematopoietic progenitor cells. We examined the effects of SF on GM-CSF or IL-3 induced proliferation of a human factor-dependent cell line, MO7. SF supported MO7 cell proliferation as well as IL-3 or GM-CSF alone, and its addition dramatically enhanced (three- to sixfold) maximal GM-CSF or IL-3 stimulated proliferation. SF did not increase the number or affinity of cell surface GM-CSF receptors. We examined several early events of signal transduction in an effort to elucidate the biochemical mechanisms of synergy of these factors. Since each of these three cytokines is believed to function in part through activation of a tyrosine kinase, we examined their effects on cellular phosphotyrosine containing proteins. Each cytokine induced rapid, transient, and concentration dependent tyrosine phosphorylation of a number of substrates. For GM-CSF and IL-3, these phosphoproteins were indistinguishable (150, 125, 106, 93, 80, 79, 73, 44, 42, and 36 kDa), while SF induced major or minor tyrosine phosphorylation of 205, 140-150, 116, 106, 94, 90, 80, 79, 73, 44, 42, 39, 36, 32 kDa phosphoproteins. Two other signal transduction intermediates known to be phosphorylated and activated by GM-CSF and IL-3, the 70-75 kDa Raf-1 kinase, and p42 mitogen-activated protein kinase-2 (MAPK), were also phosphorylated by SF. Combinations of GM-CSF or IL-3 with SF did not further increase the phosphorylation of Raf-1 or p42 MAPK when compared to any of the factors alone. In contrast SF, but not GM-CSF or IL-3, induced tyrosine phosphorylation of phospholipase C-gamma (PLC-gamma). These results indicate that SF and GM-CSF/IL-3 have partially overlapping effects on early signal transducing events, as well as striking differences, such as tyrosine phosphorylation of PLC-gamma. This cell line should provide a useful model system to investigate the complicated process of hematopoietic growth factor synergy.
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PMID:Granulocyte-macrophage colony-stimulating factor and steel factor induce phosphorylation of both unique and overlapping signal transduction intermediates in a human factor-dependent hematopoietic cell line. 138 14

Purified hematopoietic growth factors such as colony-stimulating factor-1 (CSF-1) or macrophage CSF, granulocyte-macrophage CSF, and interleukin-3 or multi-CSF, stimulate the urokinase-type plasminogen activator (u-PA) activity of murine bone marrow-derived macrophages (BMM) and resident peritoneal macrophages. Granulocyte-CSF was inactive. The increases in BMM u-PA activity were inhibited by the glucocorticoid dexamethasone, and by agents that raise intracellular cyclic adenosine monophosphate levels, including prostaglandin E2 and cholera toxin. These changes in u-PA activity were paralleled by corresponding changes in u-PA mRNA levels. Evidence was obtained for protein kinase C and phospholipase C-mediated stimulation of BMM u-PA activity and mRNA levels; however, no evidence was found for an involvement of Na+/H+ exchange or Na+, K(+)-ATPase activity, Ca2+ fluxes, or pertussis toxin-sensitive G proteins. Several findings point to a dissociation between macrophage u-PA expression and DNA synthesis.
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PMID:Activation and proliferation signals in murine macrophages. Biochemical signals controlling the regulation of macrophage urokinase-type plasminogen activator activity by colony-stimulating factors and other agents. 184 64

In murine bone marrow-derived macrophages, prelabeled with either [3H]myristic acid or [3H]arachidonic acid, the mitogenic colony stimulating factors GM-CSF and IL-3 stimulated a transient increase in [3H]diacylglycerol generation. Maximum [3H]diacylglycerol levels were detected at 10-15 min. The stimulation of [3H]diacylglycerol generation was dependent on the concentration of CSF and correlated with their ability to activate a variety of processes in the macrophage, including DNA synthesis. This is the first report to demonstrate that GM-CSF elevates diacylglycerol levels in macrophages and also to show that diacylglycerol generation may be an important signaling mechanism for IL-3 action. In conjunction with our recent demonstration that the mitogenic agents CSF-1, 12-0-tetradecanoylphorbol-13-acetate and exogenous phospholipase C also stimulate diacylglycerol generation in the macrophage (Veis and Hamilton, J.Cell.Physiol., 147, 298-305, 1991), our findings suggest that an increase in diacylglycerol levels is necessary but not sufficient for macrophage proliferation.
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PMID:GM-CSF and IL-3 stimulate diacylglycerol generation in murine bone marrow-derived macrophages. 190 23

Hemopoietic cells have an absolute requirement for survival and proliferation for specific growth factors. The growth factors maintain the critical vitality of the cells by stimulating adenosine triphosphate (ATP) synthesis and hexose transport. Intracellular alkalinization also occurs rapidly through the stimulation of the Na+/H+ antiporter. These immediate metabolic events, not initiated by serum components, appear to be necessary for the integrity of cellular viability (Fig. 6). Interleukin-3 has been shown to induce the activation of PK-C through a mechanism(s) not requiring the hydrolysis of phosphoinositol 4,5 bisphosphate. A role for Ca2+ influx or intracellular release in the action of CSFs or interleukins has not been shown. Although downregulation of cAMP has been reported in response to IL-2, the signal transduction process of CSFs and IL-2 appears not to be mediated by upregulation of cyclic nucleotide metabolism or "classical" phospholipid degradative pathways. Protein phosphorylation is clearly modulated by the hemopoietic cytokines, yet only the CSF-1 receptor has any known intrinsic kinase activity. Instead, the IL-3, GM-CSF receptors, and perhaps G-CSF appear to be coupling to kinases of both tyrosine and serine specificities. This may be a direct allosteric interaction with membrane-associated kinases or transduced through an intermediate protein such as those using GTP. Such is the case for many hormone receptors that couple to amplifying "second messenger" enzyme systems (i.e., adenylate cyclase, phospholipase C) or members of the insulin growth factor family that couple to tyrosine kinases in proximity to the receptors (IGF-II). One of the kinase systems that IL-2, IL-3, and other CSFs stimulate appears to have some characteristics similar to PK-C. Direct activators of PK-C stimulate some similar serine-threonine phosphorylation and perhaps even tyrosine phosphorylation. The hemopoietic growth factors, however, stimulate tyrosine phosphorylation of some proteins that are not phosphorylated in response to PK-C activators, suggesting that these kinase systems are independently regulated. Although phorbol esters stimulate many of the same metabolic activities (ATP synthesis in myeloid and lymphoid cell lines), growth-factor abrogation is clearly associated with the action of tyrosine kinase oncogenes or the nuclear oncogene effectors such as v-myc. It is likely, therefore, that tyrosine kinases are playing a critical role in the control of proliferation although the dominant amount of cellular protein phosphorylations are on serine. Both classes of kinases are apparently required for growth-factor action. All the hemopoietic growth factors examined thus far stimulate the steady-state accumulation of the nuclear protooncogenes.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Hematopoietic growth-factor signal transduction and regulation of gene expression. 209 Feb 58

The capacity of human neutrophils (PMN) to bind tumor necrosis factor (TNF) was rapidly lost when the cells were incubated in suspension with agents that can stimulate their migratory and secretory responses. Both physiological (poly)peptides (FMLP, C5a, CSF-GM) and pharmacologic agonists (PMN, calcium ionophore A23187) induced the loss of TNF receptors (TNF-R) from the cell surface. Half-maximal loss in TNF-R ensued after only approximately 2 min with 10(-7) M FMLP at 37 degrees C, and required only 10(-9) M FMLP during a 30-min exposure. However, there were no such changes even with prolonged exposure of PMN to FMLP at 4 degrees or 16 degrees C. Scatchard analysis revealed loss of TNF-binding sites without change in their affinity (Kd approximately 0.4 nM) as measured at incompletely modulating concentrations of FMLP, C5a, PMA, or A23187. The binding of anti-TNF-R mAbs to PMN decreased in parallel, providing independent evidence for the loss of TNF-R from the cell surface. At the same time, soluble TNF-R appeared in the medium of stimulated PMN. This inference was based on the PMN- and FMLP-dependent generation of a nonsedimentable activity that could inhibit the binding of TNF to fresh human PMN or to mouse macrophages, and the ability of mAbs specific for human TNF-R to abolish inhibition by PMN-conditioned medium of binding of TNF to mouse macrophages. Soluble TNF-R activity was associated with a protein of Mr approximately 28,000 by ligand blot analysis of cell-free supernatants of FMLP-treated PMN. Thus, some portion of the FMLP-induced loss of TNF-R from human PMN is due to shedding of TNF-R. Shedding was unaffected by inhibitors of serine and thiol proteases and could not be induced with phosphatidylinositol-specific phospholipase C. Loss of TNF-R from PMN first stimulated by other agents may decrease their responsiveness to TNF. TNF-R shed by PMN may be one source of the TNF-binding proteins found in body fluids, and may blunt the actions of the cytokine on other cells.
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PMID:Shedding of tumor necrosis factor receptors by activated human neutrophils. 216 28

Murine bone marrow-derived macrophages (BMM) undergo DNA synthesis in response to growth factors such as colony stimulating factor-1 (CSF-1) and granulocyte-macrophage CSF (GM-CSF). These macrophages can also be "activated," but without subsequent DNA synthesis, by a number of other agents, including lipopolysaccharide (LPS), concanavalin A, zymosan, formyl-methionyl-leucyl-phenylalanine (FMLP), and the Ca2+ ionophore, A23187. When BMM are treated with a range of stimuli, there is some, although not perfect, correlation between transient elevations in both c-myc mRNA and c-fos mRNA levels and increases in DNA synthesis. However, enhanced DNA synthesis and oncogene expression are readily dissociated from rises in inositol phosphates and, by implication, phospholipase C-mediated hydrolysis of phosphatidyl inositol 4,5-bisphosphate. Superoxide formation in BMM can also be dissociated from the other responses and does not necessarily depend on protein kinase C activation.
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PMID:Activation and proliferation signals in murine macrophages: relationships among c-fos and c-myc expression, phosphoinositide hydrolysis, superoxide formation, and DNA synthesis. 255 11

Hepatocyte growth factor/scatter factor (HGF/SF) is a multifunctional cytokine that induces mitogenesis, motility, invasion, and morphogenesis of several epithelial and endothelial cell lines in culture. The receptor for HGF/SF has been identified as the Met tyrosine kinase. To investigate the signaling pathways that are involved in these events, we have generated chimeric receptors containing the extracellular domain of the colony-stimulating factor-1 (CSF-1) receptor fused to the transmembrane and intracellular domains of the Met receptor (MET). Madin-Darby canine kidney (MDCK) epithelial cells expressing the CSF-MET chimera dissociate and scatter in response to CSF-1. However, cells expressing a mutant CSF-MET receptor containing a phenylalanine substitution for tyrosine 1356 were unable to scatter or form branching tubules following stimulation with CSF-1. Tyrosine 1356 is essential for the recruitment of multiple substrates including the p85 subunit of PI3-kinase, phospholipase C gamma, and Grb2. In this study, we have investigated the role of PI3-kinase and a downstream target of PI3-kinase, pp70S6K, in the induction of MDCK cell scatter in response to HGF/SF. Our results demonstrate that following stimulation with HGF/SF, activation of PI3-kinase but not pp70S6K is essential for MDCK cell scatter.
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PMID:Hepatocyte growth factor-induced scatter of Madin-Darby canine kidney cells requires phosphatidylinositol 3-kinase. 749 47

Steel factor (SF) synergizes with a variety of hemopoietins to support the growth and differentiation of human progenitor cells. The human factor-dependent cell line MO7 has been used as a model to study the interaction of SF with other growth factors such as GM-CSF, because both factors support the proliferation of this cell line and are synergistic in combination. Previous studies have shown that this effect is not readily explained by the synergistic activation of early, cytosolic signal transduction intermediates such as tyrosine kinases, Raf-1, MAP2 kinase, or phospholipase C gamma. In an attempt to further explore the biological and biochemical mechanisms of the synergy between SF and GM-CSF, we examined the effects of these growth factors on the regulation of nuclear proto-oncogenes, cell cycle control genes, and G1-->S transition of MO7 cells. Individually, GM-CSF was a much more potent growth factor for MO7 cells than SF, particularly under serum-free conditions. Only GM-CSF, but not SF, was able to stimulate G1-->S transition of MO7 cells after factor deprivation for 24 h. Northern blot analyses showed also differential effects of GM-CSF and SF on the expression of some nuclear proto-oncogenes and G1 cyclins. GM-CSF (10 ng/ml), but not SF (20 ng/ml) increased the expression of c-myc and cyclin D2 mRNA, whereas both factors caused transient increases of c-fos and cyclin D3 mRNAs. When added simultaneously, GM-CSF and SF induced an at least additive increase of c-fos mRNA expression; this effect required the presence of fetal calf serum. No additive effects of GM-CSF and SF on c-myc, cyclin D2 or D3 mRNA expression were observed. C-jun and c-myb mRNAs were constitutively expressed in the MO7 cell line, but not further increased after stimulation with GM-CSF or SF for 15 min to 48 h. The inability of SF to induce growth promoting genes such as c-myc and cyclin D2 may explain why this cytokine does not support sustained proliferation of MO7 cells. These observations suggest that SF and GM-CSF exert different effects on the expression of genes involved in regulatory pathways of cell proliferation, but the molecular mechanism of synergy remains to be elucidated.
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PMID:Signal transduction of steel factor and granulocyte-macrophage colony-stimulating factor: differential regulation of transcription factor and G1 cyclin gene expression, and of proliferation in the human factor-dependent cell line MO7. 751 43

The tyrosine phosphorylation responses initiated in human neutrophils by soluble and particulate agonists were characterized. Chemotactic factors, hematopoietic growth factors, and inflammatory microcrystals stimulated in a time- and concentration-dependent manner the tyrosine phosphorylation of distinct patterns of substrates: pp120, pp85, pp70, and pp60 in the case of chemotactic factors; pp155, pp130, pp120, pp85, pp60, and pp40 in the case of granulocyte macrophage-CSF; and pp130, pp120, pp70, and pp60 in the case of monosodium urate (MSU) crystals. Several of the single bands on one-dimensional blots (including pp40, pp70, and pp120) could be resolved into multiple spots on two-dimensional gels. The responses of several other chemotactic factors resembled those of FMLP. Cytokineplasts retained the capacity to respond to FMLP, granulocyte-macrophage-CSF, or MSU crystals with a stimulation of tyrosine phosphorylation, and contained the major substrates detected in intact neutrophils. Several unrelated tyrosine kinase inhibitors (herbimycin A, genistein, and erbstatin) strongly diminished the tyrosine phosphorylation response to chemotactic factors. Pertussis toxin abrogated the tyrosine phosphorylation response to FMLP, whereas protein kinase C (Ro 21-8220, chelerithryn) inhibitors were without effect. Chelation of intracellular calcium attenuated the tyrosine phosphorylation response to FMLP. These results indicate that G proteins play a crucial role in the coupling of chemotactic factor receptors to tyrosine phosphorylation and that this coupling occurs in parallel to that of phospholipase C. These results also underline the complexity of the transduction pathways implicated in the initiation of tyrosine phosphorylation.
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PMID:Tyrosine phosphorylation in activated human neutrophils. Comparison of the effects of different classes of agonists and identification of the signaling pathways involved. 751 26


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