Synergistic Activation of Tyrosine Phosphorylation by Orthovanadate plus Calcium Ionophore A23187 or Aromatic 1,2-Diols

Biochemistry ◽  
1994 ◽  
Vol 33 (6) ◽  
pp. 1518-1525 ◽  
Author(s):  
William R. Huckle ◽  
H. Shelton Earp
Keyword(s):  
Tyrosine Phosphorylation ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Synergistic Activation

scholarly journals Cholecystokinin-stimulated tyrosine phosphorylation of p125FAK and paxillin is mediated by phospholipase C-dependent and -independent mechanisms and requires the integrity of the actin cytoskeleton and participation of p21rho

1997 ◽  
Vol 327 (2) ◽  
pp. 461-472 ◽  
Author(s):  
J. Luis GARCÍA ◽  
A. Juan ROSADO ◽  
Antonio GONZÁLEZ ◽  
T. Robert JENSEN
Keyword(s):  
Phospholipase C ◽  
Tyrosine Phosphorylation ◽  
Inositol Phosphate ◽  
Calcium Ionophore ◽  
Cytosolic Calcium ◽  
Significant Inhibition ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Pancreatic Acini ◽  
Pkc Activation

Recent studies show that the effects of some oncogenes, integrins, growth factors and neuropeptides are mediated by tyrosine phosphorylation of the cytosolic kinase p125 focal adhesion kinase (p125FAK) and the cytoskeletal protein paxillin. Recently we demonstrated that cholecystokinin (CCK) C-terminal octapeptide (CCK-8) causes tyrosine phosphorylation of p125FAK and paxillin in rat pancreatic acini. The present study was aimed at examining whether protein kinase C (PKC) activation, calcium mobilization, cytoskeletal organization and small G-protein p21rho activation play a role in mediating the stimulation of tyrosine phosphorylation by CCK-8 in acini. CCK-8-stimulated phosphorylation of p125FAK and paxillin reached a maximum within 2.5 min. The CCK-8 dose response for causing changes in the cytosolic calcium concentration ([Ca2+]i) was similar to that for p125FAK and paxillin phosphorylation, and both were to the left of that for receptor occupation and inositol phosphate production. PMA increased tyrosine phosphorylation of both proteins. The calcium ionophore A23187 caused only 25% of the maximal stimulation caused by CCK-8. GF109203X, a PKC inhibitor, completely inhibited phosphorylation with PMA but had no effect on the response to CCK-8. Depletion of [Ca2+]i by thapsigargin had no effect on CCK-8-stimulated phosphorylation. Pretreatment with both GF109203X and thapsigargin decreased CCK-8-stimulated phosphorylation of both proteins by 50%. Cytochalasin D, but not colchicine, completely inhibited CCK-8- and PMA-induced p125FAK and paxillin phosphorylation. Treatment with Clostridium botulinum C3 transferase, which inactivates p21rho, caused significant inhibition of CCK-8-stimulated p125FAK and paxillin phosphorylation. These results demonstrate that, in pancreatic acini, CCK-8 causes rapid p125FAK and paxillin phosphorylation that is mediated by both phospholipase C-dependent and -independent mechanisms. For this tyrosine phosphorylation to occur, the integrity of the actin, but not the microtubule, cytoskeleton is essential as well as the activation of p21rho.

scholarly journals Tyrosine-specific protein phosphorylation during activation of human neutrophils

Blood ◽  
1990 ◽  
Vol 75 (12) ◽  
pp. 2445-2452 ◽  
Author(s):  
RL Berkow ◽  
RW Dodson
Keyword(s):  
Tyrosine Phosphorylation ◽  
Calcium Ionophore ◽  
Specific Protein ◽  
Leukotriene B4 ◽  
Calcium Ionophore A23187 ◽  
Human Neutrophils ◽  
Early Event ◽  
Ionophore A23187 ◽  
Protein Tyrosine Phosphorylation ◽  
Protein Tyrosine

Abstract The activation of human neutrophils by a variety of receptor-dependent and receptor-independent agonists induces the phosphorylation of a large number of proteins. Since we have previously shown that human neutrophils have at least two distinct tyrosine kinase activities, we examined protein tyrosine phosphorylation in human neutrophils stimulated with a variety of agonists. Using a monoclonal antibody specific for phosphotyrosine, the present study shows that the chemotactic peptides FMLP and leukotriene B4, the phorbol ester phorbol myristate acetate (PMA), and the calcium ionophore A23187 induce an increase in tyrosine phosphorylation of a number of neutrophil proteins. This increased protein tyrosine phosphorylation was dependent on the concentration of the agonist, as well as on the time of exposure to the agonist. Fractionation experiments showed that both a 150,000 g cytosolic and a particulate preparation showed increases in protein tyrosine phosphorylation with stimulation by FMLP or PMA, and showed that the pattern of protein tyrosine phosphorylation was slightly different in the FMLP- and PMA-stimulated cells. These data indicate that protein tyrosine phosphorylation is an early event in the activation of human neutrophils by a variety of receptor-dependent and receptor-independent agonists.

scholarly journals Tyrosine-specific protein phosphorylation during activation of human neutrophils

Blood ◽  
1990 ◽  
Vol 75 (12) ◽  
pp. 2445-2452
Author(s):  
RL Berkow ◽  
RW Dodson
Keyword(s):  
Tyrosine Phosphorylation ◽  
Calcium Ionophore ◽  
Specific Protein ◽  
Leukotriene B4 ◽  
Calcium Ionophore A23187 ◽  
Human Neutrophils ◽  
Early Event ◽  
Ionophore A23187 ◽  
Protein Tyrosine Phosphorylation ◽  
Protein Tyrosine

The activation of human neutrophils by a variety of receptor-dependent and receptor-independent agonists induces the phosphorylation of a large number of proteins. Since we have previously shown that human neutrophils have at least two distinct tyrosine kinase activities, we examined protein tyrosine phosphorylation in human neutrophils stimulated with a variety of agonists. Using a monoclonal antibody specific for phosphotyrosine, the present study shows that the chemotactic peptides FMLP and leukotriene B4, the phorbol ester phorbol myristate acetate (PMA), and the calcium ionophore A23187 induce an increase in tyrosine phosphorylation of a number of neutrophil proteins. This increased protein tyrosine phosphorylation was dependent on the concentration of the agonist, as well as on the time of exposure to the agonist. Fractionation experiments showed that both a 150,000 g cytosolic and a particulate preparation showed increases in protein tyrosine phosphorylation with stimulation by FMLP or PMA, and showed that the pattern of protein tyrosine phosphorylation was slightly different in the FMLP- and PMA-stimulated cells. These data indicate that protein tyrosine phosphorylation is an early event in the activation of human neutrophils by a variety of receptor-dependent and receptor-independent agonists.

Growth factors and the primary cilium in BALB/c 3T3 cells

1987 ◽  
Vol 45 ◽  
pp. 830-831
Author(s):  
R. W. Tucker ◽  
N. S. More ◽  
S. Jayaraman
Keyword(s):  
Growth Factors ◽  
Primary Cilium ◽  
Cultured Cells ◽  
Morphological Changes ◽  
Calcium Ionophore ◽  
Growth Stimulation ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
3T3 Cells ◽  
Microtubule Depolymerization

The mechanisms by which polypeptide growth factors Induce DNA synthesis in cultured cells is not understood, but morphological changes Induced by growth factors have been used as clues to Intracellular messengers responsible for growth stimulation. One such morphological change has been the transient disappearance of the primary cilium, a “9 + 0” cilium formed by the perinuclear centriole in interphase cells. Since calcium ionophore A23187 also produced both mitogenesis and ciliary changes, microtubule depolymerization might explain ciliary disappearance monitored by indirect immunofluorescence with anti-tubulin antibody. However, complete resorption and subsequent reformation of the primary cilium occurs at mitosis, and might also account for ciliary disappearance induced by growth factors. To settle this issue, we investigated the ultrastructure of the primary cilium using serial thin-section electron microscopy of quiescent BALB/c 3T3 cells before and after stimulation with serum.

Inhibition of Platelet Aggregation by Ethanol in Vitro Shows Specificity for Aggregating Agent Used and Is Influenced by Platelet Lipid Composition

1982 ◽  
Vol 48 (01) ◽  
pp. 049-053 ◽  
Author(s):  
C G Fenn ◽  
J M Littleton
Keyword(s):  
Platelet Aggregation ◽  
Lipid Composition ◽  
Saturated Fatty Acids ◽  
Calcium Ionophore ◽  
Cholesterol Content ◽  
Membrane Lipid ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Increased Sensitivity

SummaryEthanol at physiologically tolerable concentrations inhibited platelet aggregation in vitro in a relatively specific way, which may be influenced by platelet membrane lipid composition. Aggregation to collagen, calcium ionophore A23187 and thrombin (low doses) were often markedly inhibited by ethanol, adrenaline and ADP responses were little affected, and aggregation to exogenous arachidonic acid was actually potentiated by ethanol. Aggregation to collagen, thrombin and A23187 was inhibited more by ethanol in platelets enriched with saturated fatty acids than in those enriched with unsaturated fats. Platelets enriched with cholesterol showed increased sensitivity to ADP, arachidonate and adrenaline but this increase in cholesterol content did not appear to influence the inhibition by ethanol of platelet responses. The results suggest that ethanol may inhibit aggregation by an effect on membrane fluidity and/or calcium mobilization resulting in decreased activity of a membrane-bound phospholipase.

Effects of glucocorticoids on prostaglandin formation by human amnion

1990 ◽  
Vol 68 (6) ◽  
pp. 671-676 ◽  
Author(s):  
William Gibb ◽  
Jean-Claude Lavoie
Keyword(s):  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Isolated Cells ◽  
Stimulatory Action ◽  
Human Amnion ◽  
Human Labor ◽  
Epidermal Growth

The human amnion may be an important source of prostaglandins involved in the onset of human labor and therefore it is important to define the factors that regulate their formation in this tissue. In the present study we demonstrate that glucocorticoids inhibit prostaglandin production by freshly isolated amnion cells. The inhibitory action of the glucocorticoids, however, changes to a stimulatory action when the cells are maintained in primary culture for a few days. For both inhibition and stimulation, concentrations of 10−8 M dexamethasone or greater were required to give significant effects, and estradiol and progesterone had no effect on the prostaglandin output of the cells. Epidermal growth factor (EGF), which has previously been found to stimulate prostaglandin output by confluent amnion cells, did not alter prostaglandin output of cells initially placed in culture. Furthermore, the stimulatory action of EGF and dexamethasone appeared additive. The calcium ionophore A23187 stimulated prostaglandin output in freshly isolated cells and accentuated the inhibitory effect of dexamethasone. These studies indicate that prostaglandin formation by human amnion during pregnancy could be regulated by glucocorticoids. These steroids are easily available to the amnion by way of cortisone conversion to Cortisol by the maternal decidua. The results also indicate that amnion is capable of responding to glucocorticoids in both a stimulatory and inhibitory fashion and whether one or both actions are of importance in vivo is a question that is as yet unresolved.Key words: prostaglandins, amnion, fetal membranes, glucocorticoids, labor, pregnancy.

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