Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytotoxic necrotizing factor type 1 (CNF1) induces, in epithelial cells, the development of stress fibres via the GTPase Rho pathway. We showed that CNF1 is able to modify Rho both in vitro and in vivo. Recombinant N-terminal 33kDa (CNF1Nter) and C-terminal 14.8-31.5 kDa (CNF1Cter) regions of the CNF1 protein allowed us to demonstrate that the N-terminal region contains the cell-binding domain of the toxin and that the C-terminal region is responsible for its catalytic activity. CNF1Nter lowered the activity of CNF1 when provided to cells before the toxin whereas CNF1Cter had no effect on CNF1 cell toxicity. CNF1Cter was sufficient to induce a typical CNF1 phenotype when microinjected into African green monkey kidney cells (Vero cells), and was able to modify Rho as previously reported for CNF1. The C-terminal domain lost its catalytic activity when deleted of various subdomains, suggesting a scattered distribution of catalytic-site amino acids. Elucidation of the CNF1 functional organization and analysis of amino acid homologies between CNFs (CNF1, CNF2), Pasteurella multocida toxin (PMT) and dermonecrotic toxin of Bordetella pertussis (DNT) allowed us to postulate that CNFs and DNT act on Rho via the same enzymatic activity located in their C-terminus, and that CNFs and PMT probably bind to analogous cell receptors.
 ...
PMID:Molecular localization of the Escherichia coli cytotoxic necrotizing factor CNF1 cell-binding and catalytic domains. 922 12

The expression of G protein-coupled receptors inducing calcium mobilization and stimulating cell migration was examined in human transitional-cell carcinoma (J82) cells. Measurements of cytoplasmic Ca2+ concentration ([Ca2+]i) and phospholipase C activity indicated that these cells express several calcium-mobilizing receptors, including those for lysophosphatidic acid (LPA), thrombin, bradykinin, bombesin and histamine, of which only the LPA response was sensitive (approximately 50%) to pertussis toxin (PTX). Migration of J82 cells was strongly stimulated by LPA and thrombin, by 5- to 20-fold, whereas bradykinin, bombesin and histamine were ineffective. Migration induced by either LPA or thrombin was inhibited by the actin cytoskeleton-disrupting agent, cytochalasin B, by the Rho protein-inactivating Clostridium difficile toxin B, by preventing [Ca2+]i transients with an intracellular calcium-chelating agent, and by the phorbol ester, phorbol 12-myristate 13-acetate, which also blocked the LPA- and thrombin-induced [Ca2+]i increases. On the other hand, ADP-ribosylation of Gi type G proteins by PTX abrogated the migratory response to LPA, without affecting the thrombin effect. Similarly, raising cAMP levels inhibited, by about 50%, the LPA- but not the thrombin-induced J82 cell migration. In conclusion, human transitional-cell carcinoma (J82) cells express various G protein-coupled, calcium-mobilizing receptors, out of which only those for LPA and thrombin stimulate cell migration, indicating that phospholipase C-derived second messengers per se are not sufficient for initiating this response. The complex signal transduction processes leading to LPA- and thrombin-stimulated motility of these human carcinoma cells apparently involve several common, essential factors, such as [Ca2+]i changes and Rho protein-regulated reorganization of the cytoskeleton, as well as some distinct components, most notably distinct subtypes of heterotrimeric G proteins and apparently also distinct cAMP-sensitive targets.
 ...
PMID:Identification of G protein-coupled receptors potently stimulating migration of human transitional-cell carcinoma cells. 945 63

During inflammatory processes of the kidney, lesions of the glomerulus lead to aggregation of thrombocytes and infiltration of macrophages, which can release bioactive mediators. One of these important signalling molecules is lysophosphatidic acid (LPA). Incubation of rat mesangial cells with LPA induced mRNA and protein expression of the early-response genes pghs-2 (for prostaglandin G/H synthase-2/cyclo-oxygenase-2) and egr-1. As shown by antisense experiments, induction of egr-1 was related to the strong mitogenic effect of LPA. LPA-mediated gene expression was inhibited by pertussis toxin, indicating coupling to G-proteins of the Gi family. Specific inhibition of proteins of the small G-protein subfamily Rho with toxin B from Clostridium difficile led to changes in mesangial cell morphology without induction of apoptosis. LPA-mediated expression of pghs-2 and egr-1 was reduced to base-line levels by toxin B, indicating a role for Rho proteins in LPA-mediated gene induction. Of the two mitogen-activated protein kinase (MAPK) pathways investigated, the MAPK kinase-extracellular signal-regulated kinase pathway was involved in the induction of both pghs-2 and egr-1 mRNA expression, as shown by the inhibitory effect of PD98059. Activation of the MAPK p38, however, was only related to pghs-2 expression, whereas egr-1 expression was not affected by treatment of mesangial cells with the specific inhibitor SB203580. Taken together our data provide evidence that LPA-mediated activation of MAPK kinase and Rho proteins leads to the induction of the functionally distinct early-response genes pghs-2 and egr-1, whereas activation of MAPK p38 revealed considerable differences between the regulation of these two genes.
 ...
PMID:Lysophosphatidic acid-mediated signal-transduction pathways involved in the induction of the early-response genes prostaglandin G/H synthase-2 and Egr-1: a critical role for the mitogen-activated protein kinase p38 and for Rho proteins. 949 74

The recent identification of the Vzg-1/Edg2 protein as a functional G protein-coupled receptor for lysophosphatidic acid (LPA) has allowed a sequence-based search for new genes that may encode novel subtypes of LPA receptors. A human cDNA encoding a G protein-coupled receptor, designated Edg4, was identified by searching the GenBankTM for homologs of the human Edg2 LPA receptor. The Edg4 protein is 46% identical and 72% similar in amino acid sequence to human Edg2. When overexpressed in Jurkat T cells, the Edg4 protein mediated LPA-induced activation of a serum response element reporter gene with LPA concentration dependence (EC50 of 10 nM) and specificity. This LPA-induced reporter gene activation could be partially inhibited by pretreatment with pertussis toxin or C3 exoenzyme, suggesting requirements for both a Gi protein and Rho GTPase. Overexpression of Edg4 in Jurkat cells also led to increases in specific binding sites for [3H]LPA. Northern blots revealed that two edg4 mRNA transcripts of 1.8 and 8 kilobases are distributed very differently from edg2 mRNAs in adult human tissues and several cancer cell lines. The existence and distinctive tissue expression of structurally different subtypes of LPA receptors may provide one basis for tissue-specific functions and permit independent regulation of each subtype of LPA receptor.
 ...
PMID:Characterization of a novel subtype of human G protein-coupled receptor for lysophosphatidic acid. 952 86

Thrombin treatment causes a dose-dependent rounding of 1321N1 astrocytoma cells. This cytoskeletal response is rapid, peaking 2 h after thrombin stimulation, and reverses by 50% after 24 h. The thrombin receptor peptide SFLLRNP also induces cell rounding, whereas other G protein-linked receptor agonists such as carbachol, lysophosphatidic acid, or bradykinin fail to do so. Results of studies using pharmacological inhibitors do not support a requirement for phosphatidylinositol 3-kinase, mitogen-activated protein kinase, or Ca2+ mobilization in this response. Inhibition of protein kinase C or tyrosine kinase produces minimal blockade. Pertussis toxin treatment is also without effect. However, thrombin-induced rounding is fully blocked by the C3 toxin from Clostridium botulinum, which specifically ADP-ribosylates and inactivates the small G protein Rho. Thrombin also leads to a rapid, 2.4-fold increase in 32P incorporation into myosin light chain while carbachol does not. Myosin phosphorylation, like cell rounding is inhibited by inactivation of Rho with C3 exoenzyme, suggesting that myosin phosphorylation is necessary for this cytoskeletal response. This is supported by the observation that thrombin-induced rounding is also blocked by the myosin light chain kinase inhibitor KT5926. However, treatment with KT5926 fails to inhibit mitogenesis. Thus, cell rounding is not prerequisite to thrombin-induced DNA synthesis. We conclude that stimulation of the heterotrimeric G protein-coupled thrombin receptor in 1321N1 cells activates Rho-dependent pathways for both DNA synthesis and cell rounding, the cytoskeletal response being mediated in part through increases in myosin phosphorylation.
 ...
PMID:Requirement for Rho-mediated myosin light chain phosphorylation in thrombin-stimulated cell rounding and its dissociation from mitogenesis. 955 56

In a cell-free system from neutrophil cytosol GTP(&ggr ;)S can induce an increase in the number of free filament barbed ends and massive actin polymerisation and cross-linking. GTP(&ggr ;)S stimulation was susceptible to an excess of GDP, but not Bordetella pertussis toxin and could not be mimicked by aluminium fluoride, myristoylated GTPgammaS.Gialpha2 or Gbeta1gamma2 subunits of trimeric G proteins. In contrast, RhoGDI and Clostridium difficile toxin B (inactivating Rho family proteins) completely abrogated the effect of GTPgammaS. When recombinant, constitutively activated and GTPgammaS-loaded Rac1, RhoA, or Cdc42 proteins alone or in combination were probed at concentrations >100 times the endogenous, however, they were ineffective. Purified Cdc42/Rac-interactive binding (CRIB) domain of WASP or C3 transferase did not prevent actin polymerisation by GTPgammaS. The action of GTPgammaS was blocked by mM [Mg2+], unless a heat- and trypsin-sensitive component present in neutrophil plasma membrane was added. Liberation of barbed ends seems therefore to be mediated by a toxin B-sensitive cytosolic Rho-family protein, requiring a membrane-associated guanine nucleotide exchange factor (GEF) for its activation by GTPgammaS under physiologic conditions. The inefficiency of various protein kinase and phosphatase inhibitors (staurosporine, genistein, wortmannin, okadaic acid and vanadate) and removal of ATP by apyrase, suggests that phosphate transfer reactions are not required for the downstream propagation of the GTPgammaS signal. Moreover, exogenously added phosphoinositides failed to induce actin polymerisation and a PtdIns(4,5)P2-binding peptide did not interfere with the response to GTPgammaS. The speed and simplicity of the presented assay applicable to protein purification techniques will facilitate the further elucidation of the molecular partners involved in actin polymerisation.
 ...
PMID:GTPgammaS-induced actin polymerisation in vitro: ATP- and phosphoinositide-independent signalling via Rho-family proteins and a plasma membrane-associated guanine nucleotide exchange factor. 958 May 66

Activation of intact human neutrophils by fMLP stimulates phospholipase D (PLD) by an unknown signaling pathway. The small GTPase, ADP-ribosylation factor (ARF), and Rho proteins regulate the activity of PLD1 directly. Cell permeabilization with streptolysin O leads to loss of cytosolic proteins including ARF but not Rho proteins from the human neutrophils. PLD activation by fMLP is refractory in these cytosol-depleted cells. Readdition of myr-ARF1 but not non-myr-ARF1 restores fMLP-stimulated PLD activity. C3 toxin, which inactivates Rho proteins, reduces the ARF-reconstituted PLD activity, illustrating that although Rho alone does not stimulate PLD activity, it synergizes with ARF. To identify the signaling pathway to ARF and Rho activation by fMLP, we used pertussis toxin and wortmannin to examine the requirement for heterotrimeric G proteins of the Gi family and for phosphoinositide 3-kinase, respectively. PLD activity in both intact cells and the ARF-restored response in cytosol-depleted cells is inhibited by pertussis toxin, indicating a requirement for Gi2/Gi3 protein. In contrast, wortmannin inhibited only fMLP-stimulated PLD activity in intact neutrophils, but it has no effect on myr-ARF1-reconstituted activity. fMLP-stimulated translocation of ARF and Rho proteins to membranes is not inhibited by wortmannin. It is concluded that activation of Gi proteins is obligatory for ARF/Rho activation by fMLP, but activation of phosphoinositide 3-kinase is not required.
 ...
PMID:ADP-ribosylation factor and Rho proteins mediate fMLP-dependent activation of phospholipase D in human neutrophils. 958 56

Thrombin, the ultimate enzyme in the blood coagulation cascade, has prominent actions on various cells, including neurons. As in platelets, thrombin increases [Ca2+]i mobilization in neurons, and also retracts neurites. Both these effects are mediated through a G protein-coupled, proteolytically activated receptor for thrombin (PAR-1). Prolonged exposure to thrombin kills neurons via apoptosis, that may also involve PAR-1 activation. Increased [Ca2+]i has been a unifying mechanism proposed for cell death in several neurodegenerative diseases. Thrombin-elevated calcium levels may activate intracellular cascades in neurons leading to cell death. Since thrombin mediates its diverse effects on cells through both heterotrimeric and monomeric G proteins, we also explored what effect altering differential G protein coupling would have on the neuronal response to thrombin. We studied calcium mobilization by thrombin in a model motor neuronal cell line, NSC19, using fluorescence image analysis. Confirming effects in other neuronal types, thrombin caused dramatic increases in [Ca2+]i levels, both transiently and after prolonged exposure, which involved activation and cleavage of the PAR-1 receptor. Using enzyme linked immunosorbent assay (ELISA) and dot-blot analysis, we found that the N-terminal fragment of PAR-1 was released into the medium after exposure to thrombin. We confirmed that PAR-1 protein and mRNA expression occurred in motor neurons. We found that cholera toxin inhibited thrombin-mediated Ca2+ influx, pertussis toxin did not significantly alter thrombin action, and lovastatin, a small 21-kDa Ras GTPase (Rho) modulator, showed a tendency to reduce the thrombin effect. These data indicate that thrombin-increased [Ca2+]i, sufficient to trigger cell death in motor neurons, might be approached in vivo by modulating thrombin signaling through PAR-1.
 ...
PMID:Calcium mobilization and protease-activated receptor cleavage after thrombin stimulation in motor neurons. 958 68

To determine whether M2 muscarinic receptors are linked to the monomeric G protein Rho, we studied the effect of carbachol on actin reorganization (stress fiber formation) in cultured human airway smooth muscle cells that expressed mainly M2 muscarinic receptors by dual-fluorescence labeling of filamentous (F) and monomeric (G) actin. F-actin was labeled with FITC-labeled phalloidin, and G-actin was labeled with Texas Red-labeled DNase I. Carbachol stimulation induced stress fiber formation (increased F-actin staining) in the cells and increased the F- to G-actin ratio 3.6 +/- 0.4-fold (mean +/- SE; n = 5 experiments). Preincubation with pertussis toxin, Clostridium C3 exoenzyme, or tyrosine kinase inhibitors reduced the carbachol-induced increase in stress fiber formation and significantly decreased the F- to G-actin ratio, whereas a mitogen-activated protein kinase inhibitor, a phosphatidylinositol 3-kinase inhibitor, and a protein kinase C inhibitor were without effect. This study demonstrates that in cultured human airway smooth muscle cells, muscarinic-receptor activation induces stress fiber formation via a pathway involving a pertussis-sensitive G protein, Rho proteins, and tyrosine phosphorylation.
 ...
PMID:Carbachol-induced actin reorganization involves Gi activation of Rho in human airway smooth muscle cells. 961 96

Endothelial barrier function is regulated at the cellular level by cytoskeletal-dependent anchoring and retracting forces. In the present study we have examined the signal transduction pathways underlying agonist-stimulated reorganization of the actin cytoskeleton in human umbilical vein endothelial cells. Receptor activation by thrombin, or the thrombin receptor (proteinase-activated receptor 1) agonist peptide, leads to an early increase in stress fiber formation followed by cortical actin accumulation and cell rounding. Selective inhibition of thrombin-stimulated signaling systems, including Gi/o (pertussis toxin sensitive), p42/p44, and p38 MAP kinase cascades, Src family kinases, PI-3 kinase, or S6 kinase pathways had no effect on the thrombin response. In contrast, staurosporine and KT5926, an inhibitor of myosin light chain kinase, effectively blocked thrombin-induced cell rounding and retraction. The contribution of Rho to these effects was analyzed by using bacterial toxins that either activate or inhibit the GTPase. Escherichia coli cytotoxic necrotizing factor 1, an activator of Rho, induced the appearance of dense actin cables across cells without perturbing monolayer integrity. Accordingly, lysophosphatidic acid, an activator of Rho-dependent stress fiber formation in fibroblasts, led to reorganization of polymerized actin into stress fibers but failed to induce cell rounding. Inhibition of Rho with Clostridium botulinum exoenzyme C3 fused to the B fragment of diphtheria toxin caused loss of stress fibers with only partial attenuation of thrombin-induced cell rounding. The implication of Rac and Cdc42 was analyzed in transient transfection experiments using either constitutively active (V12) or dominant-interfering (N17) mutants. Expression of RacV12 mimicked the effect of thrombin on cell rounding, and RacN17 blocked the response to thrombin, whereas Cdc42 mutants were without effect. These observations suggest that Rho is involved in the maintenance of endothelial barrier function and Rac participates in cytoskeletal remodeling by thrombin in human umbilical vein endothelial cells.
 ...
PMID:Regulation of the actin cytoskeleton by thrombin in human endothelial cells: role of Rho proteins in endothelial barrier function. 972 17


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>