scholarly journals Leukotriene C4biosynthesis in isolated August rat peritoneal leukocytes

1996 ◽  
Vol 5 (6) ◽  
pp. 443-447
Author(s):  
J. M. Huebner ◽  
R. R. Eversole ◽  
W. F. Jackson ◽  
C. D. Mackenzie ◽  
S. R. Stapleton ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Experimental Model ◽  
Model System ◽  
Ionophore A23187 ◽  
Leukocyte Population ◽  
Kinase C ◽  
Maximal Stimulation ◽  
Peritoneal Leukocytes ◽  
Isolated Cell

The mixed leukocyte population obtained from the peritoneum of the August rat is a potentially important experimental model of inherent eosinophilia that has not been well characterized. In the present study, isolated cell preparations generated a concentration-dependent release of leukotriene (LT) C4when exposed to the Ca2+ionophore A23187, reaching maximal stimulation at 5.0 μM. This response was inhibited by the 5-lipoxygenase activating protein antagonist MK-886 (0.1 μM), nominally Ca2+and Mg2+-free incubation media and by activation of protein kinase C via phorbol 12-myristate 13-acetate (50 nM). These findings establish a model system for investigating LTC4profiles contingent with innate peritoneal eosinophilia and are consistent with the hypothesis that cellular LTC4biosynthesis is phosphoregulated.

Comparison of the modes of action of Ca2+ ionophore A23187 and thrombin in protein kinase C activation in human platelets

FEBS Letters ◽  
1985 ◽  
Vol 192 (1) ◽  
pp. 4-8 ◽  
Author(s):  
Kimihiko Sano ◽  
Hajime Nakamura ◽  
Tamotsu Matsuo ◽  
Yasuhiro Kawahara ◽  
Hisashi Fukuzaki ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Human Platelets ◽  
Ionophore A23187 ◽  
Modes Of Action ◽  
Kinase C ◽  
Protein Kinase C Activation

scholarly journals Prostacyclin inhibits platelet aggregation induced by phorbol ester or Ca2+ ionophore at steps distal to activation of protein kinase C and Ca2+-dependent protein kinases

1989 ◽  
Vol 258 (1) ◽  
pp. 57-65 ◽  
Author(s):  
W Siess ◽  
E G Lapetina
Keyword(s):  
Protein Kinase C ◽  
Platelet Aggregation ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Shape Change ◽  
Ionophore A23187 ◽  
Maximal Effect ◽  
Kinase C ◽  
Dependent Protein ◽  
High Concentrations

Suspensions of aspirin-treated, 32P-prelabelled, washed platelets containing ADP scavengers in the buffer were activated with either phorbol 12,13-dibutyrate (PdBu) or the Ca2+ ionophore A23187. High concentrations of PdBu (greater than or equal to 50 nM) induced platelet aggregation and the protein kinase C (PKC)-dependent phosphorylation of proteins with molecular masses of 20 (myosin light chain), 38 and 47 kDa. No increase in cytosolic Ca2+ was observed. Preincubation of platelets with prostacyclin (PGI2) stimulated the phosphorylation of a 50 kDa protein [EC50 (concn. giving half-maximal effect) 0.6 ng of PGI2/ml] and completely abolished platelet aggregation [ID50 (concn. giving 50% inhibition) 0.5 ng of PGI2/ml] induced by PdBu, but had no effect on phosphorylation of the 20, 38 and 47 kDa proteins elicited by PdBu. The Ca2+ ionophore A23187 induced shape change, aggregation, mobilization of Ca2+, rapid phosphorylation of the 20 and 47 kDa proteins and the formation of phosphatidic acid. Preincubation of platelets with PGI2 (500 ng/ml) inhibited platelet aggregation, but not shape change, Ca2+ mobilization or the phosphorylation of the 20 and 47 kDa proteins induced by Ca2+ ionophore A23187. The results indicate that PGI2, through activation of cyclic AMP-dependent kinases, inhibits platelet aggregation at steps distal to protein phosphorylation evoked by protein kinase C and Ca2+-dependent protein kinases.

scholarly journals Calcium mobilization and protein kinase C activation are required for cholecystokinin stimulation of pancreatic cholesterol esterase secretion

1995 ◽  
Vol 306 (2) ◽  
pp. 605-608 ◽  
Author(s):  
J Brodt-Eppley ◽  
D Y Hui
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Digestive Enzyme ◽  
Calcium Mobilization ◽  
Cholesterol Esterase ◽  
Ionophore A23187 ◽  
Prolonged Incubation ◽  
Ar42j Cells ◽  
Kinase C ◽  
Stimulation Of

The bile salt-stimulated cholesterol esterase is a digestive enzyme synthesized by the acinar cells of the pancreas. Previous results have shown that cholesterol esterase biosynthesis and secretion in the AR42J pancreatoma cells could be increased 3-5-fold by intestinal hormones such as cholecystokinin (CCK). The purpose of the current study is to explore the signalling mechanism by which CCK stimulation of AR42J cells results in increased biosynthesis and secretion of the cholesterol esterase. The results showed that the CCK-induced cholesterol esterase secretion could be mimicked by addition of the Ca2+ ionophore A23187 or by transient incubation of AR42J cells with the protein kinase C activator phorbol 12-myristate 13-acetate (PMA). Cholesterol esterase stimulation by CCK, A23187 and PMA could be abolished by the calcium chelator BAPTA or by specific protein kinase C inhibitors such as chelerythrine. Additionally, prolonged incubation of AR42J cells with PMA to reduce the protein kinase C level, also reduced CCK-stimulated cholesterol esterase secretion to a level similar to that observed in control cells. Taken together, these data suggested that CCK activation of cholesterol esterase secretion may be mediated by a Ca(2+)-dependent protein kinase C pathway, requiring increases in calcium mobilization and activation of protein kinase C.

Mechanism of action of luteinizing hormone-releasing hormone in rat ovarian cells

1989 ◽  
Vol 67 (8) ◽  
pp. 962-967 ◽  
Author(s):  
Peter C. K. Leung ◽  
Jian Wang ◽  
Kenneth G. Baimbridge
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Luteinizing Hormone ◽  
Inositol Phosphates ◽  
Ionophore A23187 ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Ovarian Cells ◽  
Kinase C

The initial step in the signal transduction of luteinizing hormone-releasing hormone (LHRH) in rat ovarian cells is the hydrolysis of membrane polyphosphoinositides into inositol phosphates and 1,2-diacylglycerol. The former compounds, especially inositol 1,4,5-triphosphate, are known to cause the release of calcium from intracellular stores, while diacylglycerol is a potent activator of protein kinase C. LHRH causes a rapid and transient increase in intracellular concentrations of free calcium ions, by approximately 4.5-fold, in the majority of granulosa cells as assessed by fura-2 microspectrofluorimetry. Like LHRH, a calcium ionophore (A23187) and activators of protein kinase C attenuate the steroidogenic response of the cells to follicle-stimulating hormone, but enhance the formation of gonadotropin-induced prostaglandin formation. These results support the concept that stimulation of polyphosphoinositide hydrolysis is intimitely involved in the direct action of LHRH at the level of the ovary.Key words: signal transduction, calcium, protein kinase C, ovary, steroid hormones.

Phorbol esters stimulate somatostatin release from cultured cells

1986 ◽  
Vol 250 (5) ◽  
pp. G686-G690 ◽  
Author(s):  
K. Sugano ◽  
J. Park ◽  
A. Soll ◽  
T. Yamada
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Esters ◽  
Cultured Cells ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Ionophore A23187 ◽  
Muscarinic Agonists ◽  
Kinase C ◽  
Somatostatin Cells

Recent studies suggest that 12-O-tetradecanoylphorbol 13-acetate (TPA), one of a family of phorbol esters that are known tumor promoters, can activate intracellular Ca2+, phospholipid-dependent protein kinase (protein kinase C) directly. To examine the possible involvement of protein kinase C-mediated mechanisms in regulating gastric somatostatin release, we studied the effects of TPA on isolated enriched canine gastric somatostatin cells in short-term culture. TPA markedly stimulated somatostatin release such that nearly 10% of total cellular content of somatostatin was released into media within 2 h of incubation. Among the phorbol compounds tested, TPA was the most potent, with half-maximum effective dose (ED50) obtained at a dose of 5 X 10(-9) M. Phorbol 12,13-dibutyrate (PDBu) also stimulated somatostatin release but with only 5% of the potency of TPA, whereas phorbol compounds with no biological activity in other systems failed to stimulate somatostatin release. In the absence of extracellular Ca2+, the effects of TPA were significantly attenuated. In contrast, stimulation of somatostatin release by forskolin (10(-4) M) was not affected by Ca2+ deprivation but was potentiated by TPA. No such potentiation was observed when TPA was combined with the Ca2+ ionophore A23187. Carbamylcholine (10(-5) M), which inhibits the stimulatory actions of beta-adrenergic agonists or dibutyryl cyclic adenosine monophosphate on somatostatin cells, also inhibited TPA-induced somatostatin release. These data suggest the presence of dual stimulatory mechanisms for gut somatostatin release, both of which are susceptible to inhibition by muscarinic agonists.

scholarly journals A role for protein kinase C in the membrane fusion necessary for platelet granule secretion

Blood ◽  
1989 ◽  
Vol 74 (7) ◽  
pp. 2405-2413 ◽  
Author(s):  
JM Gerrard ◽  
LL Beattie ◽  
J Park ◽  
SJ Israels ◽  
A McNicol ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Membrane Fusion ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ultrastructural Changes ◽  
Ionophore A23187 ◽  
Kinase C ◽  
Granule Secretion ◽  
Dimethyl Amiloride

Abstract The addition of 1-oleoyl-2-acetylglycerol (OAG), or phorbol-12- myristate-13-acetate (PMA) to platelets induced the phosphorylation of a 47,000 dalton protein (47 Kd), fusion of granule membranes with membranes of the surface connected canalicular system, the formation of large vesicles and the secretion of serotonin. 1-(5- isoquinolinesulfonyl)-2-methyl-piperazine (H7), and sphingosine, inhibitors of protein kinase C, significantly inhibited the ultrastructural changes and the phosphorylation of 47 Kd. N-(2- guanidinoethyl)-5-isoquinolinesulfonamide (HA1004), structurally similar to H7, but a weaker inhibitor of protein kinase C, did not attenuate these responses to OAG or to PMA. H7, but not HA1004, also markedly inhibited secretion induced by the synergistic combination of OAG and the calcium ionophore A23187. Amiloride and 5-(N,N dimethyl)- amiloride, inhibitors of the Na+/H+ transporter, did not inhibit the ultrastructural response and the protein phosphorylation induced by OAG, or the secretion induced by the combination of A23187 and OAG. The results link the activation of protein kinase C by diglycerides to the labilization and fusion of granule membranes important for secretion.

scholarly journals Stimulation by glucose of cyclic AMP accumulation in mouse pancreatic islets is mediated by protein kinase C

1988 ◽  
Vol 253 (1) ◽  
pp. 229-234 ◽  
Author(s):  
P Thams ◽  
K Capito ◽  
C J Hedeskov
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Pancreatic Islets ◽  
Time Course ◽  
Ionophore A23187 ◽  
Kinase C ◽  
Cyclic Amp Accumulation ◽  
Mouse Pancreatic Islets

The mechanism of glucose-stimulated cyclic AMP accumulation in mouse pancreatic islets was studied. In the presence of 3-isobutyl-1-methylxanthine, both glucose and the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA), an activator of protein kinase C, enhanced cyclic AMP formation 2.5-fold during 60 min of incubation. Both TPA-stimulated and glucose-stimulated cyclic AMP accumulations were abolished by the omission of extracellular Ca2+. The Ca2+ ionophore A23187 did not affect cyclic AMP accumulation itself, but affected the time course of TPA-induced cyclic AMP accumulation, the effect of A23187 + TPA mimicking the time course for glucose-induced cyclic AMP accumulation. A 24 h exposure to TPA, which depletes islets of protein kinase C, abolished the effects of both TPA and glucose on cyclic AMP production. Both TPA-induced and glucose-induced cyclic AMP productions were inhibited by anti-glucagon antibody, and after pretreatment with this antibody glucose stimulation was dependent on addition of glucagon. Pretreatment of islets with TPA for 10 min potentiated glucagon stimulation and impaired somatostatin inhibition of adenylate cyclase activity in a particulate fraction of islets. Carbamoylcholine, which is supposed to activate protein kinase C in islets, likewise stimulated cyclic AMP accumulation in islets. These observations suggest that glucose stimulates islet adenylate cyclase by activation of protein kinase C, and thereby potentiates the effect of endogenous glucagon on adenylate cyclase.

Protein kinase C activation and calcium mobilization decrease prolactin release from human decidual cells in early pregnancy

1993 ◽  
Vol 137 (2) ◽  
pp. 335-340 ◽  
Author(s):  
T. Kubota ◽  
S. Kamada ◽  
M. Taguchi ◽  
S. Sakamoto ◽  
T. Aso
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Early Pregnancy ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Calcium Mobilization ◽  
Ionophore A23187 ◽  
Prolactin Release ◽  
Kinase C ◽  
Decidual Cells

ABSTRACT The present study was undertaken to investigate the effects of protein kinase C (PKC) activation and calcium mobilization on the release of prolactin from human decidual cells in early pregnancy. Decidua obtained from patients in early pregnancy was enzymatically dispersed and cultured with phorbol myristate acetate (PMA) and calcium ionophore A23187 in a cell culture system. Prolactin in the medium was measured by enzyme-immunoassay. PMA, a PKC activator, dose-dependently attenuated the release of prolactin from cultured decidual cells, while a PKC inhibitor, H7, significantly (P < 0·001) diminished the effect of PMA on prolactin release. PMA had no effect on cell numbers or DNA synthesis in the decidual cells during culture. It did not significantly increase the generation of inositol phosphate in decidual cells prelabelled with myo[3H]inositol and it had no effect on intracellular calcium concentration ([Ca2 + ]i). Calcium ionophore A23187, a Ca2 +-mobilizing agent, also significantly (P<0·001) attenuated the release of prolactin and potentiated the PMA-induced suppression of prolactin release from decidual cells. These findings suggest that activation of PKC and mobilization of Ca2+ may be involved in regulating prolactin release from human decidual cells. The PMA-induced suppression of prolactin release is not triggered by phosphoinositide hydrolysis nor by the increase in [Ca2 + ]i in decidual cells. Journal of Endocrinology (1993) 137, 335–340

scholarly journals Vitamin E potentiates arachidonate release and phospholipase A2 activity in rat heart myoblastic cells

1996 ◽  
Vol 319 (2) ◽  
pp. 385-391 ◽  
Author(s):  
Khai TRAN ◽  
Jason T WONG ◽  
Edmund LEE ◽  
Alvin C. CHAN ◽  
Patrick C. CHOY
Keyword(s):  
Enzyme Activity ◽  
Protein Kinase C ◽  
Vitamin E ◽  
Protein Kinase ◽  
Phospholipase A2 ◽  
Rat Heart ◽  
Lipid Vesicles ◽  
Ionophore A23187 ◽  
Kinase C ◽  
Arachidonate Release

Cytosolic phospholipase A2 (cPLA2) selectively catalyses the release of arachidonic acid from the sn-2 position of glycerophospholipids to produce prostaglandins and leukotrienes. In this study, vitamin E enrichment of rat heart myoblastic H9c2 cells caused an increase in the release of arachidonate during ionophore (A23187) stimulation. PLA2 activity in the cytosolic fraction was also enhanced but enzyme activity in the particulate fraction was not affected by this treatment. Immunoblotting analysis with a polyclonal anti-cPLA2 antibody showed an increased level of the enzyme in vitamin E-treated cells. Direct incorporation of vitamin E into lipid vesicles in the assay mixture resulted in modulation of enzyme activity in a biphasic manner. Pretreatment of cells with phorbol 12-myristate 13-acetate, a known activator of protein kinase C, synergistically potentiated the ionophore-induced arachidonate release in both the control and vitamin E-treated cells. However, vitamin E treatment by itself did not affect the protein kinase C activity, indicating that the vitamin E-induced activation of cPLA2 was independent of the protein kinase C cascade. Collectively, these results suggest that vitamin E potentiates arachidonate release through the direct and/or indirect modulation of cPLA2 activity.

scholarly journals A Model System for Activation-Induced Alternative Splicing of CD45 Pre-mRNA in T Cells Implicates Protein Kinase C and Ras

2000 ◽  
Vol 20 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Kristen W. Lynch ◽  
Arthur Weiss
Keyword(s):  
T Cells ◽  
Protein Kinase C ◽  
Alternative Splicing ◽  
T Cell ◽  
Protein Kinase ◽  
Cell Line ◽  
T Cell Activation ◽  
Cell Activation ◽  
Model System ◽  
Kinase C

ABSTRACT Multiple isoforms of the protein tyrosine phosphatase CD45 are expressed on the surface of human T cells. Interestingly, the expression of these isoforms has been shown to vary significantly upon T-cell activation. In this report, we describe a novel cell line-based model system in which we can mimic the activation-induced alternative splicing of CD45 observed in primary T cells. Of the many proximal signaling events induced by T-cell stimulation, we show that activation of protein kinase C and activation of Ras are important for the switch toward the exclusion of CD45 variable exons, whereas events related to Ca2+ flux are not. In addition, the ability of cycloheximide to block the activation-induced alternative splicing of CD45 suggests a requirement for de novo protein synthesis. We further demonstrate that sequences which have previously been implicated in the tissue-specific regulation of CD45 variable exons are likewise necessary and sufficient for activation-induced splicing. These results provide an initial understanding of the requirements for CD45 alternative splicing upon T-cell activation, and they confirm the importance of this novel cell line in facilitating a more detailed analysis of the activation-induced regulation of CD45 than has been previously possible.

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