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: UMLS:C0043167 (pertussis)
19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the modulation of tumor necrosis factor (TNF)-mediated tumor cell lysis by cAMP. Among a panel of human breast tumor cell lines, MCF7 and MDA MB 231 were shown to be, respectively, sensitive and resistant to TNF-mediated cell lysis in vitro. 125I-labeled TNF-binding experiments demonstrated that both cell lines bind TNF, indicating that the differential sensitivity to TNF was not related to TNF receptor expression. To study the relationship between TNF-mediated cell lysis and cAMP accumulation, cAMP measurement was performed following TNF treatment. Our data show that TNF alone did not induce an enhancement of intracellular cAMP accumulation either in the TNF-sensitive or in the TNF-resistant cell line. Experiments in which cells were exposed to forskolin revealed that this cAMP elevating drug was efficient in enhancing the sensitivity to TNF of MCF7 cell line. This potentiating effect of forskolin was maximal for suboptimal concentrations of TNF (10 ng/ml), reaching up to 100% when forskolin was added at 100 microM. However, co-stimulating with forskolin of either MDA MB 231 or a TNF-resistant MCF7 clone (MCF7-R-A1) did not induce any reversal of resistance to TNF. We further assessed the interaction of TNF with transmembrane signalling and the possible involvement of guanine nucleotide-binding proteins (G-proteins). Bacterial toxin-catalyzed ADP ribosylation of MCF7 and MDA MB 231 membranes was, therefore, performed. Using cholera toxin, we demonstrate that TNF treatment did not quantitatively alter the activity of stimulatory G-proteins either in MCF7 or MDA MB 231 cell line. In contrast, pertussis toxin-catalyzed ADP ribosylation experiments suggest a functional coupling of TNF receptors to a 40-kDa pertussis toxin-sensitive G-protein in the TNF-sensitive MCF78 cell line but not in the TNF-resistant MDA MB 231 cell line. Taken together, these data indicate that cAMP might play a role in TNF-mediated cell lysis and are in support of the involvement of a pertussis toxin-sensitive G-protein in TNF-mediated MCF7 cells lysis.
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PMID:Tumor necrosis factor-mediated cell lysis in vitro: relationship to cAMP accumulation and guanine nucleotide-binding proteins. 131 37

Activated macrophages synthesize and release numerous tumoricidal soluble factors that can be divided into receptor- or nonreceptor-dependent agents. Tumor necrosis factor (TNF) would be an example of the former. In our experimental model the killing of EL4 thymoma cells by syngeneic activated macrophages involves, but not exclusively, TNF. Our results show that approximately 50% of the anti-EL4 activity expressed by macrophages can be specifically inhibited with rabbit anti-mouse TNF antibody. EL4 variants resistant to the lytic activity of TNF were still susceptible to macrophage-mediated lysis. A tumor-promoting phorbol ester, TPA, rendered TNF-sensitive and -insensitive EL4 cells resistant to M phi-mediated lysis. However, TPA down-regulated TNF-specific binding sites on both TNF-sensitive and -resistant cell surface membranes, suggesting that resistance to TNF involves postligand:receptor events. Tumor cell G-protein involvement (ADP-ribosylation), as a result of TNF-TNF receptor interactions, was investigated. The results showed that pertussis toxin was cytotoxic against TNF-sensitive and -resistant EL4 cells but not against TPA-treated target cells. Inhibitors of ADP-ribosyltransferase inhibited pertussis toxin cytotoxicity and macrophage-mediated lysis but did not interfere with recombinant TNF lytic activity.
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PMID:TPA induction of EL4 resistance to macrophage-released TNF: role of ADP-ribosylation in tumoricidal activities of TNF and other factors. 213 20

Despite numerous reports, the role of tumor necrosis factor (TNF) in polymorphonuclear leukocyte (PMN) function remains controversial. We found TNF to be a potent, pertussis toxin-independent stimulator of PMN adhesion (ED50 2.6 pM). TNF-stimulated PMN under adherent conditions released up to 65% of their transcobalamine content (ED50 3.9 pM) and increased their burst activity 10-fold (ED50 3.2 pM) as measured by the hexose monophosphate shunt, whereas PMN held in suspension hardly degranulated at all and only little burst activity was demonstrable. However, preincubation of PMN with TNF in suspension led to a decrease in cellular adhesiveness, degranulation, and burst activity in response to a secondary stimulus of TNF under adherent conditions, although cells remained fully responsive toward phorbol myristate acetate. A concomitant dose-dependent decline of TNF receptor numbers that correlated well with the inhibition of PMN function (r = 0.91) suggests receptor down-regulation as the mechanism of functional PMN deactivation. Remarkably, preincubation with other PMN stimuli such as N-formyl-methionyl-leucyl-phenylalanine, platelet-activating factor, leukotriene B4, complement component fragment 5a (C5a)/C5a (desarginated), and endotoxin also led to a reduction of TNF-specific PMN responses (cross-deactivation) from 35% (LTB4) to 90% (endotoxin), corresponding with the down-regulation of TNF receptors. Deactivation and receptor down-regulation are independent of pertussis toxin-sensitive G proteins and protein kinase C but seemed to depend on changes in calcium metabolism. Granulocyte hyporesponsiveness towards TNF in sepsis (with elevated blood levels of endotoxin and TNF) might be a mechanism of self-protection or, to the contrary, might impair a possibly central mode of host defense.
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PMID:The tumor necrosis factor receptor and human neutrophil function. Deactivation and cross-deactivation of tumor necrosis factor-induced neutrophil responses by receptor down-regulation. 216 42

The guanine nucleotide binding protein (G-protein) dependency of several of the activities of tumor necrosis factor (TNF), including cytotoxicity, inhibition of lipoprotein lipase activity, blockade of 3T3-L1 differentiation, and receptor binding were examined. TNF induced killing of the TNF-sensitive cell line L929S (ED50 = 30 pM), but had little to no effect on the TNF-resistant cell line L929R (ED50 = 5,300 pM). TNF-induced cytotoxicity in L929S was antagonized in a dose-dependent manner by pertussis toxin (sevenfold increase in ED50). However, TNF-induced cytotoxicity in L929R cells was only minimally affected by pretreatment with a high dose (50 ng/ml) of pertussis toxin (1.5-fold increase in ED50). Parallel biochemical investigations revealed that inhibition was accompanied by toxin-induced ADP ribosylation of a Gi alpha-like subunit in L929 and 3T3-L1 cell membranes. Pertussis toxin also significantly reduced TNF-induced inhibition of lipoprotein lipase activity in 3T3-L1 adipocytes and TNF blockade of 3T3-L1 preadipocyte differentiation. However, pertussis toxin pretreatment of L929S, L929R, and 3T3-L1 cell cultures had little to no effect on TNF receptor binding. These data indicate that several TNF-induced biological activities in the L929 and 3T3-L1 cell lines are partially dependent upon a pertussis toxin-sensitive G-protein.
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PMID:Tumor necrosis factor-mediated biological activities involve a G-protein-dependent mechanism. 216 71

Tumour necrosis factor (TNF) is an important mediator of endotoxin-induced vascular collapse and other inflammatory reactions. Eicosanoids have been implicated in the pathogeensis of these responses. In order to explore further the potential interactions between TNF and eicosanoid metabolism in eliciting vascular responses, we studied the effects of TNF on the bovine endothelial cell line CPAE. TNF induced cellular retraction observed by light microscope. This morphological change was monitored by the passage of iodinated protein A between adjacent cells and by release of [3H]arachidonic acid metabolites from cells. Both the morphological and functional responses were abrogated by inhibition of eicosanoid synthesis with BW755c. The release of [3H]arachidonic acid metabolites appeared to be mediated by a transient increase in phospholipase A2 activity. Phospholipase C activity was not affected by TNF. The maximal increase in phospholipase A2 activity occurred at 5 min following the addition of TNF. Phospholipase A2 activation, [3H]arachidonic acid-metabolite synthesis and passage of iodinated protein A, required both RNA and protein synthesis and were associated with an increase in the synthesis of a recently described phospholipase A2-activating protein. The Bordetella pertussis toxin, islet-activating protein, also inhibited the increase in phospholipase A2 activity, the release of [3H]arachidonic acid metabolites and the passage of iodinated protein A, suggesting that the TNF receptor-ligand interaction resulting in cellular retraction, phospholipase A2 activation and eicosanoid synthesis, is coupled through the Ni guanine nucleotide regulatory protein in these cells.
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PMID:Tumour necrosis factor (cachectin) induces phospholipase A2 activity and synthesis of a phospholipase A2-activating protein in endothelial cells. 312 74

Tumor necrosis factor (TNF) activates both p42 and p44 mitogen-activated protein kinases (MAPK) in human FS-4 fibroblasts, cells for which TNF is mitogenic. We now show that TNF activates p42 MAPK in two cell lines whose growth is inhibited by TNF. A mutant TNF that binds only to the p55 TNF receptor (TNFR) produced a similar degree of activation as wild-type TNF in FS-4 fibroblasts, indicating that the p55 TNFR is sufficient to mediate p42/p44 MAPK activation. The upstream intracellular signals that couple the TNFR to MAPK activation are still poorly defined. We now show that neither phorbol ester-sensitive protein kinase C nor Gialpha link TNF to p42/p44 MAPK activation, because pretreatment of FS-4 cells with phorbol ester to down-regulate protein kinase C or pretreatment with pertussis toxin to block Gialpha does not inhibit p42/p44 MAPK activation by TNF. To further analyze MAPK activation in FS-4 cells, we compared p42/p44 MAPK activation by TNF and epidermal growth factor (EGF). While tyrosine phosphorylation of p42/p44 MAPK was detected almost immediately (30 s) after stimulating cells with EGF, TNF-induced tyrosine phosphorylation was detected only after a more prolonged time interval (initially detected at 5 min and peaking at 15-30 min). In addition, the anti-inflammatory drug sodium salicylate, previously demonstrated to inhibit NF- kappaB activation by TNF, blocked the activation of p42/p44 MAPK in response to TNF but not in response to EGF. These findings demonstrate that the TNF and EGF receptors utilize distinct signaling molecules to couple to MAPK activation. Elucidation of the mechanism whereby sodium salicylate blocks TNF-induced p42/p44 MAPK activation may help to clarify TNF-activated signaling pathways.
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PMID:Inhibition of tumor necrosis factor-induced p42/p44 mitogen-activated protein kinase activation by sodium salicylate. 862 94

Leukocyte migration in response to cell attractant gradients or chemotaxis is a key phenomenon both in cell movement and in the inflammatory response. Chemokines are quite likely to be the key molecules directing migration of leukocytes that involve cell polarization with generation of specialized cell compartments. The precise mechanism of leukocyte chemoattraction is not known, however. In this study, we demonstrate that the CC chemokine receptors CCR2 and CCR5, but not cytokine receptors such as interleukin (IL)-2Ralpha, IL-2Rbeta, tumor necrosis factor receptor 1, or transforming growth factor betaR, are redistributed to a pole in T cells that are migrating in response to chemokines. Immunofluorescence and confocal microscopy studies show that the chemokine receptors concentrate at the leading edge of the cell on the flattened cell-substratum contact area, induced specifically by the signals that trigger cell polarization. The redistribution of chemokine receptors is blocked by pertussis toxin and is dependent on cell adhesion through integrin receptors, which mediate cell migration. Chemokine receptor expression on the leading edge of migrating polarized lymphocytes appears to act as a sensor mechanism for the directed migration of leukocytes through a chemoattractant gradient.
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PMID:Polarization of chemokine receptors to the leading edge during lymphocyte chemotaxis. 920 4

An important approach to understanding complex diseases is to reduce them into well-characterized subphenotypes that are under monogenic control. One such example is Bordetella pertussis toxin-induced histamine sensitization in mice, a subphenotype of experimental allergic encephalomyelitis and experimental allergic orchitis. This subphenotype is controlled by a single locus, Bphs, previously mapped to a 33 cM region on mouse Chromosome (Chr) 6. We achieved considerable reduction of this candidate region and constructed a YAC contig across the refined interval. Our results demonstrate that Bphs is located between D6Mit151 and a newly developed marker, EC108RR, a region containing a small cluster of genes belonging to the TNF receptor superfamily. Sequence and quantitative analysis of the candidate gene, tumor necrosis factor receptor 1 (Tnfr1, p55), indicates that it is unlikely to be Bphs. However, the location of Bphs, together with physiologic effects it shares with Tnfr1 activation, suggest that Bphs may prove to be another member of the TNF receptor superfamily.
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PMID:Physical mapping of the autoimmune disease susceptibility locus, Bphs: co-localization with a cluster of genes from the TNF receptor superfamily on mouse chromosome 6. 1044 35

Microglia are the resident immune cells of the CNS. Upon brain damage, these cells are rapidly activated and function as tissue macrophages. The first steps in this activation still remain unclear, but it is widely believed that substances released from damaged brain tissue trigger this process. In this article, we describe the effects of the blood coagulation factor thrombin on cultured rodent microglial cells. Thrombin induced a transient Ca(2+) increase in microglial cells, which persisted in Ca(2+)-free media. It was blocked by thapsigargin, indicating that thrombin caused a Ca(2+) release from internal stores. Preincubation with pertussis toxin did not alter the thrombin-induced [Ca(2+)](i) signal, whereas it was blocked by hirudin, a blocker of thrombin's proteolytic activity. Incubation with thrombin led to the production of nitric oxide and the release of the cytokines tumor necrosis factor-alpha, interleukin-6, interleukin-12, the chemokine KC, and the soluble tumor necrosis factor-alpha receptor II and had a significant proliferative effect. Our findings indicate that thrombin, a molecule that enters the brain at sites of injury, rapidly triggered microglial activation.
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PMID:Thrombin-induced activation of cultured rodent microglia. 1098 34

The cytokine tumour necrosis factor-alpha (TNF) has been implicated in autoimmune diseases and may play an indirect role in activation of pain pathways. In this study we have investigated the possibility that TNF directly activates cultured neonatal rat dorsal root ganglion (DRG) neurones and provides a signalling pathway from cells in the immune system such as macrophages to sensory neurones. Expression of TNF receptor subtypes (TNFR1 and TNFR2) on sensory neurones was identified using immunohistochemistry, fluorescence-activated cell sorting analysis and RT-PCR. Biochemical and immunocytochemical analysis showed that TNF activated p38 mitogen-activated protein kinase (p38MAPK) and c-Jun N-terminal kinase (JNK) but not p42/p44 MAPK. TNF treatment evoked transient Ca2+-dependent inward currents in 70% of DRG neurones. These TNF-evoked currents were significantly attenuated by ryanodine or thapsigargin or by inclusion of BAPTA in the patch pipette solution. Responses were also evoked in subpopulations of cultured DRG neurones by human mutant TNFs that cross-reacted with rat receptors and selectively activated TNFR1 or TNFR2 subtypes. TNF-evoked transient increases in [Ca2+]i were also detected in 34% of fura-2-loaded DRG neurones. The link between TNF receptor activation and Ca2+ release from stores remains to be elucidated. However, responses to TNF were mimicked by sphingolipids, including sphingosine-1-phosphate, which evoked a transient rises in [Ca2+]i in a pertussis toxin-insensitive manner in fura-2-loaded DRG neurones. We conclude that distinct receptors TNFR1 and TNFR2 are expressed on cultured DRG neurones and that they are functionally linked to intracellular Ca2+ mobilisation, a response that may involve sphingolipid signalling.
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PMID:TNF-alpha receptors simultaneously activate Ca2+ mobilisation and stress kinases in cultured sensory neurones. 1175 Sep 19


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