scholarly journals Signaling in TRPV1-induced platelet activating factor (PAF) in human esophageal epithelial cells

2010 ◽  
Vol 298 (2) ◽  
pp. G233-G240 ◽  
Author(s):  
Jie Ma ◽  
Karen M. Harnett ◽  
Jose Behar ◽  
Piero Biancani ◽  
Weibiao Cao
Keyword(s):  
Epithelial Cells ◽  
Western Blot ◽  
Transient Receptor Potential ◽  
Platelet Activating Factor ◽  
Calcium Ionophore ◽  
Transferase Activity ◽  
Ionophore A23187 ◽  
Acetyl Coa ◽  
Coa Transferase

Transient receptor potential channel, vanilloid subfamily member 1 (TRPV1) receptors were identified in human esophageal squamous epithelial cell line HET-1A by RT-PCR and by Western blot. In fura-2 AM-loaded cells, the TRPV1 agonist capsaicin caused a fourfold cytosolic calcium increase, supporting a role of TRPV1 as a capsaicin-activated cation channel. Capsaicin increased production of platelet activating factor (PAF), an important inflammatory mediator that acts as a chemoattractant and activator of immune cells. The increase was reduced by the p38 MAP kinase (p38) inhibitor SB203580, by the cytosolic phospholipase A2 (cPLA2) inhibitor AACOCF3, and by the lyso-PAF acetyltransferase inhibitor sanguinarin, indicating that capsaicin-induced PAF production may be mediated by activation of cPLA2, p38, and lyso-PAF acetyltransferase. To establish a sequential signaling pathway, we examined the phosphorylation of p38 and cPLA2 by Western blot. Capsaicin induced phosphorylation of p38 and cPLA2. Capsaicin-induced p38 phosphorylation was not affected by AACOCF3. Conversely, capsaicin-induced cPLA2 phosphorylation was blocked by SB203580, indicating that capsaicin-induced PAF production depends on sequential activation of p38 and cPLA2. To investigate how p38 phosphorylation may result from TRPV1-mediated calcium influx, we examined a possible role of calmodulin kinase (CaM-K). p38 phosphorylation was stimulated by the calcium ionophore A23187 and by capsaicin, and the response to both agonists was reduced by a CaM inhibitor and by CaM-KII inhibitors, indicating that calcium induced activation of CaM and CaM-KII results in P38 phosphorylation. Acetyl-CoA transferase activity increased in response to capsaicin and was inhibited by SB203580, indicating that p38 phosphorylation in turn causes activation of acetyl-CoA transferase to produce PAF. Thus epithelial cells produce PAF in response to TRPV1-mediated calcium elevation.

Acetyl-CoA:lyso-Platelet-Activating Factor Acetyltransferase Activity in Neutrophils from Asthmatic Patients and Normal Subjects

1993 ◽  
Vol 85 (4) ◽  
pp. 455-463 ◽  
Author(s):  
Neil L. A. Misso ◽  
Robyn L. Gillon ◽  
Marcia L. Taylor ◽  
Geoffrey A. Stewart ◽  
Philip J. Thompson
Keyword(s):  
Platelet Activating Factor ◽  
Calcium Ionophore ◽  
Normal Subjects ◽  
Transferase Activity ◽  
Ionophore A23187 ◽  
Acetyltransferase Activity ◽  
Asthmatic Patients ◽  
Control Subjects ◽  
Factor Production ◽  
The Mean

1. Platelet-activating factor is a putative mediator of inflammation in asthma and the enzyme acetyl-CoA:lyso-platelet-activating factor acetyltransferase appears to be important in regulating platelet-activating factor production by leucocytes. To determine whether there are differences in acetyl-transferase activity between asthmatic patients and normal subjects, enzyme activity was assayed in neutrophil lysates from atopic asthmatic patients (n = 20), aspirin-sensitive asthmatic patients (n = 12) and healthy, non-atopic, non-asthmatic control subjects (n = 20), both basally and after stimulation with the calcium ionophore A23187. 2. For a range of acetyl-CoA concentrations, acetyl-transferase activity (nmol of [acetyl-3H]PAF min−1 mg−1 of protein) in unstimulated neutrophils from atopic asthmatic patients was significantly higher than that for normal subjects (P = 0.038) and the mean Vmax. for atopic asthmatic patients [18.4 (SD 6.9) nmol min−1 mg−1 of protein] was significantly greater than that for the control subjects [14.9 (SD 4.6) nmol min−1 mg−1 of protein P <0.05]. The mean Vmax. for aspirin-sensitive asthmatic patients [15.9 (SD 6.9) nmol min−1 mg−1 of protein] was not significantly different from that for the normal subjects. 3. The mean ratio Vmax. stimulated/ Vmax. unstimulated for acetyltransferase from atopic asthmatic patients (1.71, SD 0.45) was significantly less than that for the normal subjects (2.13, SD 0.63, P <0.05), suggesting that acetyltransferase from atopic asthmatic patients was less sensitive to stimulation with A23187 in vitro. The mean ratio Vmax. stimulated/ Vmax. unstimulated for aspirin-sensitive asthmatic patients (2.05, SD 0.71) was not significantly different from that for the normal subjects. 4. Vmax. stimulated was significantly correlated with Vmax. unstimulated in atopic asthmatic patients (P = 0.0001) and aspirin-sensitive asthmatic patients (P = 0.012), but not in normal subjects (P = 0.071). 5. These results suggest that, in atopic asthmatic patients, neutrophils may be subject to chronic priming in vivo for increased acetyltransferase activity and capacity for platelet-activating factor synthesis. In these patients the increased platelet-activating factor production may be contributing significantly to the degree of inflammation associated with their asthma.

scholarly journals Platelet-activating factor both stimulates and "primes" human polymorphonuclear leukocyte actin filament assembly

Blood ◽  
1987 ◽  
Vol 70 (6) ◽  
pp. 1921-1927 ◽  
Author(s):  
M Shalit ◽  
GA Dabiri ◽  
FS Southwick
Keyword(s):  
Actin Filament ◽  
Polymorphonuclear Leukocyte ◽  
Actin Polymerization ◽  
Platelet Activating Factor ◽  
Calcium Ionophore ◽  
Leukotriene B4 ◽  
Calcium Ionophore A23187 ◽  
Optimal Concentration ◽  
Ionophore A23187 ◽  
Filament Assembly

Abstract The phospholipid inflammatory mediator, platelet-activating factor (PAF), can stimulate polymorphonuclear leukocyte (PMN) chemotaxis. Conversion of cytoplasmic actin from monomers to filaments is associated with PMN motile functions. Using the fluorescent actin filament stain nitrobenzodiaxole phallicidin, we have investigated PAF's effects on human PMN actin polymerization. Concentrations of PAF between 1 x 10(-11) to 1 x 10(-6) mol/L induced actin filament (F- actin) assembly. An optimal concentration of PAF (1–5 x 10(-8) mol/L) induced a significantly lower rise in relative F-actin content (1.72 +/- 0.07 SEM) than an optimal concentration (5 x 10(-7) mol/L) of the chemotactic peptide FMLP (2.21 +/- 0.06). Unlike FMLP (F-actin content: 1.25 +/- 0.04 at five seconds), PAF stimulation was associated with a delay of more than five seconds (1.04 +/- 0.01 at five seconds) before an increase in F-actin could be detected. F-actin concentration reached maximum levels by 30 to 60 seconds. Prolonged stimulation (20 minutes) with PAF was associated with two phases of polymerization and depolymerization. Like FMLP, the initiation of actin filament assembly by PAF required receptor occupancy, this reaction being totally blocked by the PAF receptor inhibitor, SKI 63–441. As evidenced by the lack of inhibition by nordihydroguaiaretic acid (5 to 20 mumol/L), the production of leukotriene B4 was not required for the PAF-induced changes in F-actin. Like FMLP, PAF's ability to stimulate PMN actin polymerization was inhibited by pertussis toxin (.05 to 2.5 micrograms/mL) but not impaired by the addition of EGTA and/or the calcium ionophore A23187. Preincubation with 1 x 10(-11) to 1 x 10(-8) mol/L PAF for 2 to 60 minutes enhanced the rise in F-actin content induced by low concentrations of FMLP (5 x 10(-12) to 1 x 10(-10) mol/L) indicating that this phospholipid was capable of “priming” the PMN actin polymerization response.

Tobacco smoke releases performed mediators from canine mast cells and modulates prostaglandin production

1992 ◽  
Vol 263 (1) ◽  
pp. L67-L72
Author(s):  
P. S. Thomas ◽  
R. E. Schreck ◽  
S. C. Lazarus
Keyword(s):  
Mast Cells ◽  
Tobacco Smoke ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Prostaglandin D2 ◽  
Ionophore A23187 ◽  
Temperature Dependent ◽  
Prostaglandin Production ◽  
Lungs And Airways

The role of an extract of tobacco smoke in activating mast cells was studied. With the use of isolated, canine mast cells as a model, we found that cigarette smoke solution (CSS) induced the release of the performed mediators histamine and tryptase from these cells in an energy- and temperature-dependent, non-cytotoxic manner. There was no requirement for extracellular calcium. Nicotine tartrate did not reproduce the effect of CSS. Interestingly, mast cells produced little prostaglandin D2 (PGD2) in response to the CSS, and there was a concentration-related inhibition of calcium ionophore A23187-induced PGD2 synthesis. This suggests at least two mechanisms acting on the mast cell: tobacco smoke can directly activate mast cells to release performed mediators and can simultaneously inhibit prostaglandin production. These observations suggest a mechanism by which mast cells may participate in the bronchospastic and proinflammatory changes seen in the lungs and airways of smokers.

scholarly journals Calcium ionophore synergizes with bacterial lipopolysaccharides in activating macrophage arachidonic acid metabolism.

1988 ◽  
Vol 167 (2) ◽  
pp. 623-631 ◽  
Author(s):  
A A Aderem ◽  
Z A Cohn
Keyword(s):  
Arachidonic Acid ◽  
Acid Metabolism ◽  
Calcium Ionophore ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Rapid Release ◽  
Lipoxygenase Products ◽  
Order Of Magnitude ◽  
Bacterial Lipopolysaccharides

LPS, a major component of Gram-negative bacterial cell walls, prime macrophages for greatly enhanced arachidonic acid [20:4] metabolism when the cells are subsequently stimulated. The LPS-primed macrophage has been used as a model system in which to study the role of Ca2+ in the regulation of 20:4 metabolism. The Ca2+ ionophore A23187 (0.1 microM) triggered the rapid release of 20:4 metabolites from LPS-primed macrophages but not from cells not previously exposed to LPS. Macrophages required exposure to LPS for at least 40 min before A23187 became effective as a trigger. A23187 (0.1 microM) also synergized with PMA in activating macrophage 20:4 metabolism. The PMA effect could be distinguished from that of LPS since no preincubation with PMA was required. A23187 greatly increased the amount of lipoxygenase products secreted from LPS-primed macrophages, leukotriene C4 synthesis being increased 150-fold. LPS-primed macrophages, partially permeabilized to Ca2+ with A23187, were used to titrate the Ca2+ concentration dependence of the cyclooxygenase and lipoxygenase pathways. Cyclooxygenase metabolites were detected at an order of magnitude lower Ca2+ concentration than were lipoxygenase products. The data suggest that Ca2+ regulates macrophage 20:4 metabolism at two distinct steps: an increase in intracellular Ca2+ regulates the triggering signal and relatively higher Ca2+ concentrations are required for 5-lipoxygenase activity.

Effect of parathyroid hormone on transport by toad and turtle bladder

1987 ◽  
Vol 252 (1) ◽  
pp. R63-R68
Author(s):  
S. Sabatini ◽  
N. A. Kurtzman
Keyword(s):  
Parathyroid Hormone ◽  
Epithelial Cells ◽  
Calcium Uptake ◽  
Short Circuit ◽  
Calcium Ionophore ◽  
Toad Bladder ◽  
Base Line ◽  
Ionophore A23187 ◽  
45Ca Uptake ◽  
Turtle Bladder

We recently demonstrated that parathyroid hormone (PTH) inhibited both vasopressin- and cyclic AMP-stimulated water transport in the toad bladder. This was associated with an increase in calcium uptake by isolated epithelial cells. We postulated that PTH exerts its action on H2O transport by directly stimulating calcium uptake. The current study was designed to compare the effects of PTH and the calcium ionophore, A23187, on H2O and Na transport and H+ secretion in toad and turtle bladders. In toad bladder, PTH and A23187 decreased arginine vasopressin (AVP)-stimulated H2O flow and short-circuit current (SCC) after 60 min serosal incubation. In turtle bladder A23187 decreased SCC to 79.3 +/- 3.6% of base line (P less than 0.05), and significantly decreased RSCC as well. PTH had no effect on SCC or H+ secretion in turtle bladders. Both PTH and A23187 increased 45Ca uptake in toad bladder epithelial cells; only A23187 increased 45Ca uptake in the turtle bladder. The different action of PTH in these two membranes, compared with that of the calcium ionophore, illustrates the selectivity of PTH on membrane transport. PTH increases calcium uptake and decreases transport only in a hormone-sensitive epithelium, whereas the ionophore works in virtually all living membranes. The mode of action of these two agents to increase calcium uptake is, therefore, likely different.

Leptin is involved in acrosome reaction by facilitating activation of MAPK cascades in the Chinese mitten crab, Eriocheir sinensis

2020 ◽  
Vol 70 (1) ◽  
pp. 81-95
Author(s):  
Qing Li ◽  
Haitao Zhao ◽  
Lin He ◽  
Hongdan Yang ◽  
Qun Wang
Keyword(s):  
Acrosome Reaction ◽  
Calcium Ionophore ◽  
Eriocheir Sinensis ◽  
Calcium Ionophore A23187 ◽  
Mitogen Activated Protein Kinase ◽  
Ionophore A23187 ◽  
Mapk Cascades ◽  
Mitten Crab ◽  
Mitogen Activated Protein

Abstract The role of leptin has been documented in several studies, including activated threonine phosphorylation of extracellular signal-regulated kinase (ERK1/2) in the reproduction of rodents and humans. Our previous studies have demonstrated that mitogen-activated protein kinase (MAPK) cascades ERK, P38, and c-Jun N-terminal kinase (JNK) are involved in the spermatogenesis and acrosome reaction of Eriocheir sinensis. Therefore, the aim of this study was to investigate the expression of leptin and its receptor (LepR), and the effect of leptin on MAPK cascades during calcium ionophore A23187-induced spermatozoa acrosome reaction in crabs. Successful western blotting revealed a 16 kDa band for leptin, and 120 kDa and 90 kDa bands for the obese receptor (LepR), respectively, in the tested male reproductive tissues. Both leptin and LepR were localized at the pro-acrosomal vesicle and apical cap (AC) of spermatids, suggesting their role in the subsequent acrosome reaction. Moreover, acrosome reaction can be enhanced by leptin, and this effect decreased due to the anti-LepR antibody. Afterwards, we investigated the effects of leptin on MAPK cascades. The results showed that leptin mainly activated the phosphorylation of ERK, P38 and JNK proteins in the apical cap during the acrosome reaction in crab spermatozoa. This study addresses the role of leptin on spermatozoa, and suggests that leptin may induce molecular changes associated with spermatozoa during acrosome reaction.

scholarly journals Nitric oxide and peroxynitrite trigger and enhance release of neutrophil extracellular traps

2019 ◽  
Vol 77 (15) ◽  
pp. 3059-3075 ◽  
Author(s):  
Aneta Manda-Handzlik ◽  
Weronika Bystrzycka ◽  
Adrianna Cieloch ◽  
Eliza Glodkowska-Mrowka ◽  
Ewa Jankowska-Steifer ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrosative Stress ◽  
Calcium Ionophore ◽  
Neutrophil Extracellular Traps ◽  
Calcium Ionophore A23187 ◽  
Human Neutrophils ◽  
Ionophore A23187 ◽  
Inflammatory Reactions ◽  
Extracellular Traps

Abstract Despite great interest, the mechanism of neutrophil extracellular traps (NETs) release is not fully understood and some aspects of this process, e.g. the role of reactive nitrogen species (RNS), still remain unclear. Therefore, our aim was to investigate the mechanisms underlying RNS-induced formation of NETs and contribution of RNS to NETs release triggered by various physiological and synthetic stimuli. The involvement of RNS in NETs formation was studied in primary human neutrophils and differentiated human promyelocytic leukemia cells (HL-60 cells). RNS (peroxynitrite and nitric oxide) efficiently induced NETs release and potentiated NETs-inducing properties of platelet activating factor and lipopolysaccharide. RNS-induced NETs formation was independent of autophagy and histone citrullination, but dependent on the activity of phosphoinositide 3-kinases (PI3K) and myeloperoxidase, as well as selective degradation of histones H2A and H2B by neutrophil elastase. Additionally, NADPH oxidase activity was required to release NETs upon stimulation with NO, as shown in NADPH-deficient neutrophils isolated from patients with chronic granulomatous disease. The role of RNS was further supported by increased RNS synthesis upon stimulation of NETs release with phorbol 12-myristate 13-acetate and calcium ionophore A23187. Scavenging or inhibition of RNS formation diminished NETs release triggered by these stimuli while scavenging of peroxynitrite inhibited NO-induced NETs formation. Our data suggest that RNS may act as mediators and inducers of NETs release. These processes are PI3K-dependent and ROS-dependent. Since inflammatory reactions are often accompanied by nitrosative stress and NETs formation, our studies shed a new light on possible mechanisms engaged in various immune-mediated conditions.

scholarly journals Cross-regulation of cortisol secretion by adrenocorticotropin and platelet-activating factor in perfused guinea pig adrenals

2007 ◽  
Vol 195 (1) ◽  
pp. 29-38
Author(s):  
Toshio Shimada ◽  
Taeko Hirose ◽  
Itsuro Matsumoto ◽  
Tadaomi Aikawa
Keyword(s):  
Protein Kinase ◽  
Guinea Pig ◽  
Platelet Activating Factor ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Cortisol Response ◽  
Cortisol Secretion ◽  
Induced Signal ◽  
Dependent Processes

We examined the cross-regulation of signaling between ACTH-and platelet-activating factor (PAF)-mediated steroidogenesis in the perfused guinea pig adrenal gland. Our method of in situ perfusion using an artificial medium can evaluate whether cortisol secretion in response to ACTH and PAF is interactive. Treating adrenal glands with 100 pg/ml ACTH diminished the subsequent cortisol response to 10 nM PAF. By contrast, PAF resulted in subsequent potentiation of ACTH-induced cortisol secretion. A mixture of 50 μM l-α-1-oleoyl-2-acetyl-sn-glycerol (OAG), an activator of protein kinase C (PKC), and 3.3 μM calcium ionophore (A23187), or 10 μM forskolin (FRK) diminished the cortisol response to PAF, whereas that to ACTH was unaffected. Each of PAF, ACTH, or FRK eliminated the cortisol response to OAG plus A23187, whereas that to FRK was unaffected. These data show that the protein kinase A (PKA)-dependent processes activated by ACTH or FRK can interfere with PAF-induced signal transduction at receptor and post-receptor levels. In contrast, PKC-dependent processes activated by PAF promoted ACTH-signaling at receptor and post-receptor level. Cross-regulation between processes activated by PAF receptor–PKC and by ACTH receptor–PKA might function in the multifactorial regulation of adrenocortical steroidogenesis.

scholarly journals Platelet-activating factor acts on cortisol secretion by perfused guinea-pig adrenals via calcium-/phospholipid-dependent mechanisms

2005 ◽  
Vol 184 (2) ◽  
pp. 381-391 ◽  
Author(s):  
Toshio Shimada ◽  
Taeko Hirose ◽  
Itsuro Matsumoto ◽  
Tadaomi Aikawa
Keyword(s):  
Protein Kinase ◽  
Guinea Pig ◽  
Platelet Activating Factor ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Breakdown Product ◽  
Ionophore A23187 ◽  
Cortisol Secretion ◽  
Cortisol Responses ◽  
Paf Receptor

Bilateral adrenals of the guinea pig were perfused in situ with an artificial medium equilibrated with 95% O2/5% CO2. Platelet-activating factor (PAF) induced biphasic cortisol responses, which reached a maximum at 10 nM PAF and declined at 100 nM. The effect of the PAF receptor antagonists CV-3988 and CV-6209 on PAF-stimulated cortisol secretion was examined. Prior exposure of adrenal glands to 10 μM CV-3988 or a simultaneous incubation with 10 μM CV-6209 abolished the cortisol response to 10 nM PAF. Lyso-PAF (a PAF precursor and breakdown product) did not affect cortisol secretion. Concentrations of 5–12.5 μM 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), a protein kinase C (PKC) inhibitor, abolished subsequent cortisol secretion in response to 10 nM PAF. N-[2-(Methylamino)ethyl]-5-isoquinoline sulfonamide dihydrochloride (H-8), a protein kinase A inhibitor, was less effective. A calcium ionophore (A23187) at 3.3 and 10 μM increased cortisol secretion, but the activator of PKC, l-α-1-oleoyl-2-acetyl-sn-3-glycerol (OAG), at 50 μM had no effect. When infused simultaneously, OAG (50 μM) and A23187 (3.3 μM) stimulated cortisol secretion synergistically. The secretory response of cortisol to repeated infusions of adrenocortico-trophin (100 pg/ml) or forskolin (10 μM) was essentially reproducible. By contrast, cortisol secretion in response to repeated infusions of PAF (10 nM) or OAG plus A23187 was not reproducible and the second response was diminished compared with the first. Our findings suggest that PAF plays a role in the regulation of steroidogenesis via a mechanism mediated by the PAF receptor and PKC.

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