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)

The chemotactic peptide f-Met-Leu-Phe (fMLP) stimulates leukocyte functions through binding and activation of a specific G-protein-coupled formyl peptide receptor (FPR). Recent studies have shown that stimulation of neutrophils with fMLP induces the activation of two members of the mitogen-activated protein kinase (MAP kinase) family, ERK1 and ERK2, through mechanisms that are not completely understood but may involve the phosphorylation of the adapter protein SHC by the Src-related kinase Lyn. In this study, transfected fibroblasts expressing the rabbit FPR were used to investigate further the role of Lyn and SHC phosphorylation in fMLP-stimulated MAP kinase activation. Stimulation of transfected cells with fMLP resulted in the time- and dose-dependent increase in tyrosine phosphorylation and activation of ERK1 and ERK2 and the activation of MEK, the MAP kinase/ERK kinase. The activation of both ERKs and MEK was inhibited by preincubation of the cells with pertussis toxin, indicating that activation was dependent upon a Gi/Go-like protein that couples to the receptor. Our data also show that, unlike neutrophils, FPR-transfected fibroblasts do not express the Src-related kinase Lyn. In the absence of Lyn, fMLP stimulation did not result in an increased tyrosine phosphorylation of the adapter protein SHC, whereas it was still able to induce MAP kinase activation. These data suggest that Lyn and SHC are not the only upstream signals for activation of the MAP kinase/ERK pathway by fMLP and demonstrate the potential application of the FPR-transfected cells for the delineation of additional signaling mechanisms stimulated by fMLP.
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PMID:Activation of the mitogen-activated protein kinase pathway by fMet-leu-Phe in the absence of Lyn and tyrosine phosphorylation of SHC in transfected cells. 866 60

The formyl peptide receptor on human neutrophils recognizes bacterial, N-formylated peptides and initiates a cascade of intracellular signals via a pertussis toxin sensitive Gi protein. We used fluorescence techniques to investigate the interactions of ligand (L), receptor (R), and G proteins (G), the ternary complex, in both live and fixed human neutrophils. By lightly fixing permeabilized neutrophils with a procedure that retained ligand binding, we were able to "capture' R and G in different configurations in the absence of ligand. Fixed receptors were trapped in a high affinity form (attributed to LRG) that could not be rapidly converted to low affinity by the addition of GTP[S]. Adding saturating nucleotide prior to fixation trapped receptors in a low affinity form (attributed to LR). The low affinity receptors retained the sensitivity of the native receptors to the presence of NA+. The distribution between high and low affinity receptors was modulated by GTP[S] in a dose dependent manner. The ability to redistribute low and high affinity receptor forms prior to fixation was unique to GTP[S], as compared to other non-activating nucleotides, suggesting that GTP[S] can regulate the distribution between R and RG. We suggest that precoupled receptors that give rise to high affinity ligand binding are likely to exist in native membranes in human neutrophils.
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PMID:Fixation traps formyl peptide receptors in high and low affinity forms that can be regulated by GTP[S] in the absence of ligand. 877 31

The regulation of the cytoskeletal localization of guanine-nucleotide-binding protein alpha i subunits by formyl peptide receptors was studied in myeloid differentiated human leukemia (HL-60) cells. Stimulation of formyl peptide receptors with N-formyl-Met-Leu-Phe (fMet-Leu-Phe) transiently increased the amount of alpha i subunits in the Triton X-100-insoluble cytoskeleton. Similar to the biphasic regulation of the actin content, fMet-Leu-Phe ( > or = 10 nM) rapidly increased the cytoskeletal alpha i content (about threefold at 30 s), which was followed by a rapid reversal to control levels. The formyl peptide receptor increased the cytoskeletal content of both alpha i subtypes, alpha i2 and alpha i3- present in HL-60 cells. In cells permeabilized with Staphylococcus aureus alpha-toxin, fMet-Leu-Phe increased binding of the stable GTP analogue, guanosine 5'-[gamma-thio]triphosphate (GTP[S]), to cytoskeletal proteins in a pertussis-toxin-sensitive manner, which was completely abolished by the F-actin-disrupting agent, cytochalasin B. Using the photoreactive GTP analogue, m-acetylanilido-GTP, the formyl peptide receptor-regulated GTP binding sites at the cytoskeleton were identified as 40-kDa proteins, the molecular size of alpha i subunits. Cytoskeleton prepared from stimulated cells did not exhibit increased GTP[S] binding, which suggests that activated alpha i subunits are translocated to the cytoskeleton. Finally, in alpha-toxin-permeabilized HL-60 cells, fMet-Leu-Phe and GTP[S] cooperatively stimulated actin polymerization. In conclusion, evidence is provided that chemoattractant receptors cause translocation of activated alpha i subunits to the cytoskeleton coincidentally with F-actin formation. The data therefore argue for a potential role of translocated alpha i subunits in the process of receptor-induced actin polymerization.
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PMID:Receptor-induced translocation of activated guanine-nucleotide-binding protein alpha i subunits to the cytoskeleton in myeloid differentiated human leukemia (HL-60) cells. 877 23

Transfection of either the C5a receptor or the formyl peptide receptor into undifferentiated U937 cells generated continuously growing cell lines that stably expressed these receptors. The transfected cells displayed significant numbers of cell surface receptors that had ligand binding properties similar to fully differentiated U937 cells. Undifferentiated transfected U937 cells were capable of a ligand-specific calcium flux and showed migratory responses that were qualitatively and quantitatively similar to differentiated cells and were specific for each chemoattractant. Moreover, the chemotactic response could be desensitized by preincubating the cells in a high concentration of ligand and could be blocked by pertussis toxin. These results demonstrate that undifferentiated U937 cells possess the subcellular signaling apparatus and machinery necessary to generate a motile response and that the only missing component for chemotaxis is expression of a chemoattractant receptor. In addition, the results demonstrate that undifferentiated U937 cells transfected with chemoattractant receptors provide a defined model system to study receptor structure/function relationships and may be used to investigate receptor-mediated chemotactic responses in a relevant human myeloid cell.
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PMID:Undifferentiated U937 cells transfected with chemoattractant receptors: a model system to investigate chemotactic mechanisms and receptor structure/function relationships. 906 Apr 56

The human formyl peptide receptor (FPR) expressed in RBL-2H3 transfectants (RBL[FPR]) behaves qualitatively like the FPR expressed by neutrophils except that it causes sustained F-actin accumulation and cell shape change responses on formyl peptide stimulation. These sustained responses were not accounted for by changes in the transfected receptor's ability to interact with ligand or by receptor density. Signal transduction pathways of transfected and neutrophil FPRs are apparently similar. In transfected cells, dissociation of ligand is sensitive to guanine nucleotide, the G protein is pertussis toxin-sensitive, FPR and G protein appear to be precoupled, the F-actin response is stimulated with the same dose-response profile as in neutrophils, and the F-actin accumulation response is directly regulated by the FPR, even long after initial stimulation. Potentially significant differences between neutrophil and transfected FPR were found when receptor processing was measured. In neutrophils, practically 100% of the FPR is converted to forms that dissociate slowly from ligand and are inactive in signal transduction within 2 min of ligand stimulation. By contrast, 20% or more of transfected FPR remains rapidly dissociating even 5 min after stimulation. Although 80% of neutrophil FPR is internalized by 5 min after stimulation, transfected FPR appears to plateau at 50-60% internalized. Because actin responses in neutrophils are regulated by a small number of active receptors, the inefficiency of receptor inactivation in RBL(FPR) transfectants may account for the prolonged F-actin accumulation response.
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PMID:Relationship of ligand-receptor dynamics to actin polymerization in RBL-2H3 cells transfected with the human formyl peptide receptor. 933 25

We studied the function of the platelet integrin alphaIIb beta3 using a B lymphocyte model in which alphaIIb beta3 can be induced to interact with fibrinogen using phorbol myristate acetate (PMA). To determine whether a G protein-coupled receptor could also activate alphaIIb beta3 in lymphocytes, we coexpressed the human formyl peptide receptor (fPR) and alphaIIb beta3, finding that the fPR agonist formyl Met-Leu-Phe (fMLP)-stimulated lymphocyte adherence to immobilized fibrinogen and binding of soluble fibrinogen to the lymphocyte surface. The response to fMLP, but not PMA, was abrogated by pertussis toxin, indicating that the fPR was coupled to the G-protein Galphai, whereas the protein kinase C inhibitor bisindolylmaleimide I inhibited the response to both fMLP and PMA, indicating that signaling from the fPR included protein kinase C. On the other hand, the tyrosine kinase inhibitor genistein, the Syk inhibitor piceatannol, and the RhoA inhibitor C3 exoenzyme had no effect, implying that neither tyrosine phosphorylation nor the GTPase RhoA were involved. Furthermore, whereas micromolar concentrations of cytochalasin D inhibited the PMA-stimulated interaction of alphaIIb beta3 with fibrinogen, nanomolar concentrations actually induced fibrinogen binding to unstimulated cells. Our studies demonstrate that alphaIIb beta3 expressed in B lymphocytes can be activated by a physiologic agonist and outline an activating pathway that includes Galphai, protein kinase C, and the actin cytoskeleton.
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PMID:Regulation of alphaIIb beta3 function in human B lymphocytes. 961 43

Activation of the N-formyl peptide receptor (FPR) of human neutrophils by ligands such as N-formyl-methionine-leucine-phenylalanine (fMLP) induces mobilization of intracellular calcium, cell adhesion, chemotaxis, superoxide production and degranulation. Chinese hamster ovary (CHO) cells are normally devoid of FPR and unresponsive to fMLP, but when stably transfected with a human FPR cDNA, exhibited some of these same responses. Specifically, stimulation with fMLP resulted in release of intracellular calcium and chemotactic migration toward a gradient of fMLP. As in neutrophils, both processes were inhibited through receptor desensitization by prior exposure to a higher or equal concentration of ligand or by treatment with pertussis toxin. Soluble and membrane-bound fibronectin greatly increased fMLP-induced chemotaxis of CHO cells expressing FPR, but not of wild-type CHO cells, suggesting a role for FPR in activation of integrin function. Evidence for this hypothesis was obtained by demonstrating that CHO cells expressing FPR rapidly increased their adhesion to a fibronectin-coated surface after stimulation with fMLP. Both chemotaxis and adhesion were largely inhibited by RGDS peptide and a function-blocking antibody against alpha5 integrin. FPR-mediated chemotaxis of the CHO transfectants was partly inhibited by a tyrosine kinase inhibitor, herbimycin A, and blocked by a phosphoinositide 3-kinase inhibitor, wortmannin. These data suggest that stimulation of CHO FPR transfectants with a gradient of fMLP results in phosphoinositide 3-kinase-dependent chemotactic migration, which is enhanced by binding of activated alpha5beta1 to fibronectin. This non-myeloid, non-lymphoid fibroblastic cell line will thus serve as a useful model to investigate additional requirements of signal transduction molecules, adhesion molecules and cytoskeletal elements in FPR-mediated chemotaxis.
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PMID:Chemotaxis of chinese hamster ovary cells expressing the human neutrophil formyl peptide receptor: role of signal transduction molecules and alpha5beta1 integrin. 964 40

The formyl peptide receptor (FPR) couples to pertussis toxin (PTX)-sensitive Gi-proteins to activate chemotaxis and exocytosis in neutrophils. PTX reduces not only formyl peptide-stimulated but also agonist-independent ("basal") Gi-protein activity, suggesting that the FPR is constitutively active. We aimed at identifying an inverse FPR agonist, i.e. a compound that suppresses constitutive FPR activity. In Sf9 insect cell membranes, the G-protein heterotrimer Gialpha2beta1gamma2 reconstituted N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-stimulated guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) binding and GTPgammaS-sensitive high affinity [3H]FMLP binding. The FPR "antagonist" cyclosporin H (CsH) potently and efficiently reduced basal GTPgammaS binding in Sf9 membranes. Another FPR antagonist, N-t-butoxycarbonyl-L-phenylalanyl-L-leucyl-L-phenylalanyl-L-leucyl-L- phenylalanine did not inhibit basal GTPgammaS binding but blocked the inhibitory effect of CsH on GTPgammaS binding. Na+ reduced basal GTPgammaS binding and eliminated the inhibitory effect of CsH. Similar effects of FMLP, CsH, and Na+ as in Sf9 membranes were observed with FPR expressed in the mammalian cell line HEK293. Our data show that the human FPR possesses high constitutive activity. CsH is an inverse FPR agonist and stabilizes the FPR in an inactive state. Na+ also stabilizes the FPR in an inactive state and, thereby, diminishes inverse agonist efficacy.
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PMID:High constitutive activity of the human formyl peptide receptor. 972 41

Sphingosine-1-phosphate (SPP) produced from sphingosine by sphingosine kinase has recently been reported to act as intracellular second messenger for a number of plasma membrane receptors. In the present study, we investigated whether the sphingosine kinase/SPP pathway is involved in cellular signaling of the Gi protein-coupled formyl peptide receptor in myeloid differentiated human leukemia (HL-60) cells. Receptor activation resulted in rapid and transient production of SPP by sphingosine kinase, which was abolished after pertussis toxin treatment. Direct activation of heterotrimeric G proteins by AlF4- also rapidly increased SPP formation in intact HL-60 cells. In cytosolic preparations of HL-60 cells, sphingosine kinase activity was stimulated by the stable GTP analog, guanosine 5'-O-(3-thiotriphosphate). Inhibition of sphingosine kinase by DL-threo-dihydrosphingosine and N,N-dimethylsphingosine did not affect phospholipase C stimulation and superoxide production but markedly inhibited receptor-stimulated Ca2+ mobilization and enzyme release. We conclude that the formyl peptide receptor stimulates through Gi-type G proteins SPP production by sphingosine kinase, that the enzyme is also stimulated by direct G protein activation, and that the sphingosine kinase/SPP pathway apparently plays an important role in chemoattractant signaling in myeloid differentiated HL-60 cells.
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PMID:Formyl peptide receptor signaling in HL-60 cells through sphingosine kinase. 993 90

A leucine zipper-like domain, T21/DP107, located in the amino terminus of the ectodomain of gp41, is crucial to the formation of fusogenic configuration of the HIV-1 envelope protein gp41. We report that the synthetic T21/DP107 segment is a potent stimulant of migration and calcium mobilization in human monocytes and neutrophils. The activity of T21/DP107 on phagocytes was pertussis toxin-sensitive, suggesting this peptide uses Gi-coupled seven-transmembrane receptor(s). Since the bacterial chemotactic peptide fMLP partially desensitized the calcium-mobilizing activity of T21/DP107 in phagocytes, we postulated that T21/DP107 might preferentially use a lower affinity fMLP receptor. By using cells transfected to express cloned prototype chemotactic N-formyl peptide receptor (FPR) or its variant, FPR-like 1 (FPRL1), we demonstrate that T21/DP107 activates both receptors but has a much higher efficacy for FPRL1. In addition, T21/DP107 at nM concentrations induced migration of FPRL1-transfected human embryonic kidney 293 cells. In contrast, fMLP did not induce significant chemotaxis of the same cells at a concentration as high as 50 microM. Although a lipid metabolite, lipoxin A4, was a high-affinity ligand for FPRL1, it was not reported to induce Ca2+ mobilization or chemotaxis in FPRL1-transfected cells. Therefore, T21/DP107 is a first chemotactic peptide agonist identified thus far for FPRL1. Our results suggest that this peptide domain of the HIV-1 gp41 may have the potential to activate host innate immune response by interacting with FPR and FPRL1 on phagocytes.
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PMID:T21/DP107, A synthetic leucine zipper-like domain of the HIV-1 envelope gp41, attracts and activates human phagocytes by using G-protein-coupled formyl peptide receptors. 1022 29


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