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.

Prolactin stimulation of ornithine decarboxylase and mitogenesis in Nb2 node lymphoma cells: The role of protein kinase C and calcium mobilization

1986 ◽  
Vol 12 (1) ◽  
pp. 37-51 ◽  
Author(s):  
Arthur R. Buckley ◽  
David W. Montgomery ◽  
Ruthann Kibler ◽  
Charles W. Putnam ◽  
Charles F. Zukoski ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Ornithine Decarboxylase ◽  
Calcium Mobilization ◽  
Lymphoma Cells ◽  
Kinase C ◽  
Stimulation Of

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

Effects of staurosporine on protein kinase C and amylase secretion from pancreatic acini

1989 ◽  
Vol 257 (4) ◽  
pp. G548-G553 ◽  
Author(s):  
T. B. Verme ◽  
R. T. Velarde ◽  
R. M. Cunningham ◽  
S. R. Hootman
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Digestive Enzyme ◽  
Amylase Secretion ◽  
Ionophore A23187 ◽  
Functional Protein ◽  
Amylase Release ◽  
Pancreatic Acini ◽  
Kinase C ◽  
Protein Kinase C Activity

The effects of staurosporine, a recently isolated microbial alkaloid, on amylase secretion and protein kinase C activity of guinea pig pancreatic acini were investigated. Staurosporine at a concentration of 1 microM completely inhibited both acinar protein kinase C activity (IC50 = 5.5 +/- 1.4 nM) and amylase secretion induced by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) (IC50 = 4.1 +/- 0.4 nM). At this concentration, staurosporine reduced amylase secretion elicited by maximally effective concentrations of carbachol and cholecystokinin by approximately 50% but did not appreciably alter the potencies of the two secretagogues. In the presence of staurosporine, amylase secretion induced by carbachol was linear for at least 60 min. Staurosporine had no effect on amylase release elicited by the Ca2+ ionophore A23187. It did, however, inhibit secretion induced by vasoactive intestinal peptide, although with a reduced potency relative to its effects on amylase release stimulated by TPA, carbachol, and cholecystokinin (IC50 = 34 +/- 17 nM). These results indicate that staurosporine is a potent inhibitor of protein kinase C activity in pancreatic acini and that protein kinase C has an important role as an intracellular mediator of digestive enzyme secretion induced by cholecystokinin and carbachol in the acinar cell. In addition, a separate staurosporine-insensitive coupling pathway, most likely involving Ca2+, appears to be equally important and can maintain long-term secretion in the absence of functional protein kinase C activity.

scholarly journals Ca2+ -dependent activation of oxoglutarate dehydrogenase by vasopressin in isolated hepatocytes

1985 ◽  
Vol 225 (2) ◽  
pp. 327-333 ◽  
Author(s):  
J M Staddon ◽  
J D McGivan
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Isolated Hepatocytes ◽  
Activation Mechanism ◽  
Ionophore A23187 ◽  
Kinase C ◽  
Initial Activation ◽  
Oxoglutarate Dehydrogenase ◽  
Stimulation Of

Vasopressin stimulated gluconeogenesis from proline in hepatocytes from starved rats; this was attributed to an activation of oxoglutarate dehydrogenase (EC 1.2.4.2) [Staddon & McGivan (1984) Biochem. J. 217, 477-483]. The role of Ca2+ in the activation mechanism was investigated. (1) In the absence of extracellular Ca2+, vasopressin caused a stimulation of gluconeogenesis and a decrease in cell oxoglutarate content that were markedly transient when compared with the effects in the presence of Ca2+. (2) Ca2+ added to cells stimulated for 2 min by vasopressin in the absence of extracellular Ca2+ sustained the initial effects of vasopressin. Ca2+ added 15 min after vasopressin, a time at which both the rate of gluconeogenesis and the cell oxoglutarate content were close to the control values, caused a stimulation of gluconeogenesis and a decrease in cell oxoglutarate content. (3) Under conditions of cell-Ca2+ depletion, vasopressin had no effect on gluconeogenesis or cell oxoglutarate content. (4) Ionophore A23187 stimulated gluconeogenesis and caused a decrease in cell oxoglutarate content, but the phorbol ester 4 beta-phorbol 12-myristate 13-acetate had no effects. (5) These data suggest that the initial activation of oxoglutarate dehydrogenase by vasopressin is dependent on an intracellular Ca2+ pool and independent of extracellular Ca2+. For activation of a greater duration, a requirement for extracellular Ca2+ occurs. The activation of oxoglutarate dehydrogenase by A23187 is consistent with a mechanism involving Ca2+, but the lack of effect of 4 beta-phorbol 12-myristate 13-acetate indicates that protein kinase C is not involved in the mechanism of activation by vasopressin.

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

Regulation of oxytocin secretion by the ovine corpus luteum: effect of activators of protein kinase C

1990 ◽  
Vol 124 (2) ◽  
pp. 225-232 ◽  
Author(s):  
J. J. Hirst ◽  
G. E. Rice ◽  
G. Jenkin ◽  
G. D. Thorburn
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Corpus Luteum ◽  
Phospholipase C ◽  
Tissue Slices ◽  
Kinase C ◽  
Luteal Tissue ◽  
Dose Dependent ◽  
Stimulation Of

ABSTRACT The effect of protein kinase C activation and dibutyryl cyclic AMP on oxytocin secretion by ovine luteal tissue slices was investigated. Several putative regulators of luteal oxytocin secretion were also examined. Oxytocin was secreted by luteal tissue slices at a basal rate of 234·4 ± 32·8 pmol/g per h (n = 24) during 60-min incubations.Activators of protein kinase C: phorbol 12,13-dibutyrate (n = 8), phorbol 12-myristate,13-acetate (n = 4) and 1,2-didecanoylglycerol (n = 5), caused a dose-dependent stimulation of oxytocin secretion in the presence of a calcium ionophore (A23187; 0·2 μmol/l). Phospholipase C (PLC; 50–250 units/l) also caused a dose-dependent stimulation of oxytocin secretion by luteal slices. Phospholipase C-stimulated oxytocin secretion was potentiated by the addition of an inhibitor of diacylglycerol kinase (R59 022; n = 4). These data suggest that the activation of protein kinase C has a role in the stimulation of luteal oxytocin secretion. The results are also consistent with the involvement of protein kinase C in PLC-stimulated oxytocin secretion. The cyclic AMP second messenger system does not appear to be involved in the control of oxytocin secretion by the corpus luteum. Journal of Endocrinology (1990) 124, 225–232

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.

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