scholarly journals Regulation of GH3 pituitary tumour-cell adenylate cyclase activity by activators of protein kinase C

1989 ◽  
Vol 262 (3) ◽  
pp. 829-834 ◽  
Author(s):  
L A Quilliam ◽  
P R M Dobson ◽  
B L Brown
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Maximal Response ◽  
Kinase C ◽  
Cyclic Amp Accumulation ◽  
Stimulation Of

The influence of protein kinase C (PKC) activation on cyclic AMP production in GH3 cells has been studied. The stimulation of cyclic AMP accumulation induced by forskolin and cholera toxin was potentiated by 4 beta-phorbol 12,13-dibutyrate (PDBu). Moreover, PDBu, which causes attenuation of the maximal response to vasoactive intestinal polypeptide (VIP), also induced a small right shift in the dose-response curve for VIP-induced cyclic AMP accumulation. PDBu-stimulated cyclic AMP accumulation was unaffected by pretreatment of cells with pertussis toxin or the inhibitory muscarinic agonist, oxotremorine. PDBu stimulation of adenylate cyclase activity required the presence of a cytosolic factor which appeared to translocate to the plasma membrane in response to the phorbol ester. The diacylglycerol-generating agents thyroliberin, bombesin and bacterial phospholipase C each stimulated cyclic AMP accumulation, but, unlike PDBu, did not attenuate the stimulation induced by VIP. These results suggest that PKC affects at least two components of the adenylate cyclase complex. Stimulation of cyclic AMP accumulation is probably due to modification of the catalytic subunit, whereas attenuation of VIP-stimulated cyclic AMP accumulation appears to be due to the phosphorylation of a different site, which may be the VIP receptor.

scholarly journals Insulin and vasopressin elicit inhibition of cholera-toxin-stimulated adenylate cyclase activity in both hepatocytes and the P9 immortalized hepatocyte cell line through an action involving protein kinase C

1995 ◽  
Vol 312 (3) ◽  
pp. 769-774 ◽  
Author(s):  
L Zeng ◽  
M D Houslay
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Cholera Toxin ◽  
Cell Line ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
3T3 Cells ◽  
Kinase C ◽  
Nih 3T3

Incubation of hepatocytes or the SV40-DNA-immortalized hepatocyte P9 cell line with cholera toxin led to a time-dependent activation of adenylate cyclase activity, which occurred after a defined lag period. When added together with cholera toxin, each of the hormones insulin and vasopressin was capable of attenuating the maximum stimulatory effect achieved by cholera toxin over a period of 60 min through a process which could be blocked by the compounds staurosporine and chelerythrine. Attenuating effects on cholera-toxin-stimulated adenylate cyclase activity could also be elicited by using either the protein kinase C (PKC)-stimulating phorbol ester PMA (phorbol 12-myristate 13-acetate) or the protein phosphatase inhibitor okadaic acid. Alkaline phosphatase treatment of membranes reversed the inhibitory effect of PMA. Cholera toxin also stimulated the adenylate cyclase activity of intact CHO (Chinese-hamster ovary) and NIH-3T3 cells, but this activity was insensitive to the addition of PMA. Overexpression of various PKC isoforms in CHO cell lines did not confer sensitivity to inhibition by PMA upon cholera-toxin-stimulated adenylate cyclase activity. Rather, overexpression of the gamma isoform of PKC allowed PMA to stimulate adenylate cyclase activity in CHO cells. It is suggested that the PKC-mediated phosphorylation of a membrane protein attenuates cholera-toxin-stimulated adenylate cyclase activity in hepatocytes and P9 cells. The cellular selectivity of such an action may be due to the target for this inhibitory action of PKC being a particular isoform of adenylate cyclase which provides the major activity in hepatocytes and P9 cells, but not in either CHO or NIH-3T3 cells.

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.

scholarly journals Multiple non-specific effects of sphingosine on adenylate cyclase and cyclic AMP accumulation in S49 lymphoma cells preclude its use as a specific inhibitor of protein kinase C

1990 ◽  
Vol 268 (2) ◽  
pp. 507-511 ◽  
Author(s):  
J A Johnson ◽  
R B Clark
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Mammalian Cells ◽  
Specific Inhibitor ◽  
Lymphoma Cells ◽  
Specific Effects ◽  
Kinase C ◽  
Cyclic Amp Accumulation

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.

Protein kinase C differentially modulates PTH- and PGE2-sensitive adenylate cyclase in osteoblast-like cells

1992 ◽  
Vol 262 (1) ◽  
pp. E87-E95
Author(s):  
A. M. Freyaldenhoven ◽  
G. E. Gutierrez ◽  
M. D. Lifschitz ◽  
M. S. Katz
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Enzyme Activation ◽  
Catalytic Subunit ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Osteosarcoma Cell ◽  
Kinase C ◽  
Umr 106

The effects of phorbol 12-myristate 13-acetate (PMA), a known activator of protein kinase C, on receptor-mediated stimulation of adenylate cyclase were evaluated in a rat osteosarcoma cell line (UMR-106) with the osteoblast phenotype. Pretreatment of UMR-106 cells with PMA increased parathyroid hormone (PTH)-stimulated adenylate cyclase activity and inhibited prostaglandin E2 (PGE2)-responsive enzyme activity. In addition, PMA enhanced enzyme activation by forskolin, which is thought to exert a direct stimulatory action on the catalytic subunit of adenylate cyclase. The regulatory effects of PMA were concentration dependent and of rapid onset (less than or equal to 1 min). Treatment with PMA also resulted in translocation of protein kinase C activity from the cytosol to the particulate cell fraction. Pertussis toxin, which attenuates inhibition of adenylate cyclase mediated by the inhibitory guanine nucleotide-binding regulatory protein (Gi), augmented PTH-sensitive adenylate cyclase activity and reduced the incremental increase in PTH response produced by PMA. The results suggest that activation of protein kinase C increases PTH-stimulated adenylate cyclase activity by actions on Gi and/or the catalytic subunit and decreases PGE2 responsiveness by a mechanism involving the PGE2 receptor.

scholarly journals A role for protein kinase C-mediated phosphorylation in eliciting glucagon desensitization in rat hepatocytes

1995 ◽  
Vol 307 (1) ◽  
pp. 281-285 ◽  
Author(s):  
A Savage ◽  
L Zeng ◽  
M D Houslay
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Adenylate Cyclase ◽  
Protein Phosphatase ◽  
Rat Hepatocytes ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Glucagon Receptor ◽  
Kinase C ◽  
Phosphorylation Reaction

An immobilized hepatocyte preparation was used to show that both vasopressin and glucagon could desensitize the ability of glucagon to increase intracellular cyclic AMP concentrations. This process was not dependent on any influx of extracellular Ca2+ and was not mediated by any rise in the intracellular level of Ca2+. The protein kinase C-selective inhibitors chelerythrine, staurosporine and calphostin C acted as potent inhibitors of the desensitization process but with various degrees of selectivity regarding their ability to inhibit the desensitizing actions of glucagon and vasopressin. The protein phosphatase inhibitor okadaic acid was just as potent as vasopressin and glucagon in causing desensitization. Treatment of hepatocyte membranes with alkaline phosphatase restored to near control levels the ability of glucagon to stimulate adenylate cyclase activity in membranes from both glucagon- and vasopressin-treated (desensitized) hepatocytes. It is suggested that the desensitization of glucagon-stimulated adenylate cyclase activity involves a reversible phosphorylation reaction with the likely target being the glucagon receptor itself.

scholarly journals Parathyroid hormone induces protein kinase C but not adenylate cyclase in adult cardiomyocytes and regulates cyclic AMP levels via protein kinase C-dependent phosphodiesterase activity

1995 ◽  
Vol 310 (2) ◽  
pp. 439-444 ◽  
Author(s):  
K D Schlüter ◽  
M Weber ◽  
H M Piper
Keyword(s):  
Protein Kinase C ◽  
Parathyroid Hormone ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Phosphodiesterase Activity ◽  
Beta Adrenoceptor ◽  
Kinase C ◽  
Adult Cardiomyocytes ◽  
Cyclic Amp Accumulation

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.

Protein kinase C activating phorbolesters enhance the cyclic AMP response to parathyroid hormone, forskolin and choleratoxin in mouse calvarial bones and rat osteosarcoma cells

1991 ◽  
Vol 11 (4) ◽  
pp. 203-211 ◽  
Author(s):  
Maria Ransjö
Keyword(s):  
Protein Kinase C ◽  
Parathyroid Hormone ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Phorbol Esters ◽  
Osteosarcoma Cells ◽  
Kinase C ◽  
Cyclic Amp Accumulation ◽  
Umr 106

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.

scholarly journals The rapid desensitization of glucagon-stimulated adenylate cyclase is a cyclic AMP-independent process that can be mimicked by hormones which stimulate inositol phospholipid metabolism

1987 ◽  
Vol 243 (1) ◽  
pp. 39-46 ◽  
Author(s):  
G J Murphy ◽  
V J Hruby ◽  
D Trivedi ◽  
M J O Wakelam ◽  
M D Houslay
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Membrane Fraction ◽  
Phospholipid Metabolism ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Kinase C ◽  
Independent Process ◽  
Inositol Phospholipid ◽  
Stimulation Of

Treatment of intact hepatocytes with glucagon, TH-glucagon [(1-N-alpha-trinitrophenylhistidine, 12-homoarginine]glucagon), angiotensin or vasopressin led to a rapid time- and dose-dependent loss of the glucagon-stimulated response of the adenylate cyclase activity seen in membrane fractions isolated from these cells. Intracellular cyclic AMP concentrations were only elevated with glucagon. All ligands were capable of causing both desensitization/loss of glucagon-stimulated adenylate cyclase activity and stimulation of inositol phospholipid metabolism in the intact hepatocytes. Maximally effective doses of angiotensin precluded any further inhibition/desensitizing action when either glucagon or TH-glucagon was subsequently added to these intact cells, as has been shown previously for the phorbol ester TPA (12-O-tetradecanoylphorbol 13-acetate) [Heyworth, Wilson, Gawler & Houslay (1985) FEBS Lett. 187, 196-200]. Treatment of intact hepatocytes with these various ligands caused a selective loss of the glucagon-stimulated adenylate cyclase activity in a washed membrane fraction and did not alter the basal, GTP-, NaF- and forskolin-stimulated responses. Angiotensin failed to inhibit glucagon-stimulated adenylate cyclase activity when added directly to a washed membrane fraction from control cells. Glucagon GR2 receptor-stimulated adenylate cyclase is suggested to undergo desensitization/uncoupling through a cyclic AMP-independent process, which involves the stimulation of inositol phospholipid metabolism by glucagon acting through GR1 receptors. This action can be mimicked by other hormones which act on the liver to stimulate inositol phospholipid metabolism. As the phorbol ester TPA also mimics this process, it is proposed that protein kinase C activation plays a pivotal role in the molecular mechanism of desensitization of glucagon-stimulated adenylate cyclase. The site of the lesion in desensitization is shown to be at the level of coupling between the glucagon receptor and the stimulatory guanine nucleotide regulatory protein Gs, and it is suggested that one or both of these components may provide a target for phosphorylation by protein kinase C.

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