Protein kinase C isozymes differentially affect intracellular cyclic AMP accumulation

1990 ◽  
Vol 183 (3) ◽  
pp. 749-750
Author(s):  
F. Gusovsky ◽  
J.S. Gutkind
1988 ◽  
Vol 253 (1) ◽  
pp. 229-234 ◽  
Author(s):  
P Thams ◽  
K Capito ◽  
C J Hedeskov

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.


1990 ◽  
Vol 268 (2) ◽  
pp. 507-511 ◽  
Author(s):  
J A Johnson ◽  
R B Clark

Recent studies with phorbol esters have suggested that protein kinase C (PKC) may play a role in the regulation of adenylate cyclase in mammalian cells. Since D-sphingosine has been reported to specifically inhibit PKC in many cell types, we evaluated its effects on stimulation of cyclic AMP accumulation by adrenaline in S49 lymphoma cells. We found sphingosine to have multiple non-specific effects which could not be explained by an inhibition of PKC. These effects included: (i) inhibition by sphingosine (50 microM) of adrenaline-stimulated cyclic AMP accumulation and sphingosine permeation of the cells which rendered them leaky to ATP; (iii) sphingosine (20 microMs) augmentation of adrenaline-stimulated cyclic AMP accumulation; (iii) inhibition by sphingosine of adrenaline-stimulated adenylate cyclase in isolated membranes by up to 95%; and (iv) sphingosine (20 microM) inhibition of cellular mechanisms for the elimination of cyclic AMP. These results demonstrate the importance of evaluating the non-specific effects of sphingosine before concluding that its actions are the consequences of a specific inhibition of PKC.


1995 ◽  
Vol 310 (2) ◽  
pp. 439-444 ◽  
Author(s):  
K D Schlüter ◽  
M Weber ◽  
H M Piper

Adult ventricular cardiomyocytes have been identified as target cells for parathyroid hormone (PTH) but little is known about its signal transduction in these cells. In the present study the influence of PTH on cyclic AMP accumulation and the activity of protein kinase C (PKC) in cardiomyocytes was evaluated. A mid-regional synthetic fragment of PTH, PTH-(28-48), which exerts a hypertrophic effect on cardiomyocytes, increased the activity of membrane-associated PKC in a dose-dependent manner (1-100 nM). Activated membranous PKC was dependent on Ca2+ and sensitive to an inhibitor of Ca(2+)-dependent isoforms of PKC. When adenylate cyclase was stimulated by the addition of isoprenaline, a beta-adrenoceptor agonist, PTH-(28-48) antagonized cyclic AMP accumulation. This antagonistic effect of PTH-(28-48) could be mimicked by activation of PKC with a phorbol ester and inhibited by isobutylmethylxanthine, a phosphodiesterase inhibitor. An N-terminal synthetic fragment, PTH-(1-34), which includes an adenylate cyclase-activating domain, did not stimulate the accumulation of cyclic AMP in cardiomyocytes. The results demonstrate that in adult cardiomyocytes PTH (1) is able to stimulate PKC, (2) is not able to cause accumulation of cyclic AMP and (3) functionally antagonizes the effect of beta-adrenoceptor stimulation to increase cellular cyclic AMP concentrations via PKC-dependent phosphodiesterase activity.


Nature ◽  
1985 ◽  
Vol 314 (6009) ◽  
pp. 359-361 ◽  
Author(s):  
David Sugden ◽  
Jiri Vanecek ◽  
David C. Klein ◽  
Thomas P. Thomas ◽  
Wayne B. Anderson

1991 ◽  
Vol 11 (4) ◽  
pp. 203-211 ◽  
Author(s):  
Maria Ransjö

The protein kinase C-(PKC) activating phorbol esters 12-O-tetradecanoylphorbol-13-acetate (TPA; 100 nmol/l) and phorbol 12, 13-dibutyrate (PDBU; 100 nmol/l) enhanced basal cyclin AMP accumulation in cultured neonatal mouse calvaria. The cyclic AMP response to parathyroid hormone (PTH; 10 nmol/l) and the adenylate cyclase activators forskolin (1–3 μmol/l) and choleratoxin (0.1 μmg/ml) was potentiated in a more than additive manner by TPA and PDBU. In contrast, phorbol 13-monoacetate (phorb-13; 100 nmol/l), a related compound but inactive on PKC, had no effect on basal or stimulated cyclic AMP accumulation. In the presence of indomethacin (1μmol/l), TPA and PDBU had no effect on cyclic AMP accumulation in calvarial bones per se, but were still able to cause a significant enhancement of the response to PTH, forskolin and choleratoxin. PTH-, forskolin- and choleratoxin-stimulated cyclic AMP accumulation in rat osteosarcoma cells UMR 106-01 was synergistically potentiated by TPA and PDBU, but not by phorb.-13. These data indicate that PKC enhances cyclic AMP formation and that the level of interaction may be at, or distal to, adenylate cyclase.


Sign in / Sign up

Export Citation Format

Share Document