Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The possibility that an increased intracellular concentration of cyclic AMP (cAMP) can regulate the extent of muscarinic receptor-stimulated phosphoinositide (PPI) turnover in the human neuroblastoma cell line SK-N-SH was examined. Addition of either forskolin (or its water-soluble analog, L-85,8051), theophylline, isobutylmethylxanthine, or cholera toxin, agents that interact with either the catalytic unit of adenylate cyclase, cAMP phosphodiesterase, or the guanine nucleotide binding protein linked to adenylate cyclase activation, resulted in a 45-181% increase in cAMP concentration and a 27-70% inhibition of carbachol-stimulated inositol phosphate release. Through the use of digitonin-permeabilized cells, the site of inhibition was localized to a step at, or distal to, the guanine nucleotide binding protein that regulates phospholipase C activity. In contrast, when intact SK-N-SH cells were exposed to prostaglandin E1, the ensuing increases in cAMP were not accompanied by an inhibition of stimulated PPI turnover. These differential effects of increased cAMP concentrations on stimulated PPI turnover may reflect the compartmentation of cAMP within SK-N-SH cells.
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PMID:Muscarinic receptor-stimulated phosphoinositide turnover in human SK-N-SH neuroblastoma cells: differential inhibition by agents that elevate cyclic AMP. 247 99

Muscarinic receptor stimulation increased the accumulation of 3H-inositol phosphates in PC12 cells whose phospholipids had been prelabeled with [3H]inositol. Muscarine also inhibited the increase in cyclic AMP (cAMP) accumulation caused by 5'-N-ethylcarboxamide adenosine or by vasoactive intestinal peptide. This effect of muscarine was apparently due to the inhibition of adenylate cyclase rather than to a stimulation of a cAMP specific phosphodiesterase. The muscarinic receptor antagonist pirenzepine inhibited both the stimulation of inositol-phospholipid metabolism and the inhibition of cAMP production with Ki values of 0.34 microM and 0.36 microM, respectively. PC12 cells contained a single class of N-[3H]methylscopolamine ([3H]NMS) binding sites. Competition studies with muscarine (KD, 15 microM) and pirenzepine (Ki, 0.12 microM) revealed no evidence for multiple muscarinic receptors. The Ki of pirenzepine for the inhibition of [3H]NMS binding and the inhibition of muscarinic actions is consistent with the possibility that this is not an M1 receptor. Muscarine inhibited cAMP accumulation in cells made deficient in protein kinase C; therefore, this protein kinase is probably not involved in mediating the inhibitory effect of muscarine. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate also inhibited cAMP accumulation in PC12 cells but the mechanism of this effect differed from that of muscarine. Bradykinin caused a large increase in the accumulation of 3H-inositol phosphates and [3H]diacylglycerol relative to muscarine but did not inhibit cAMP production. Oxotremorine inhibited cAMP accumulation but it did not stimulate inositol-phospholipid metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Muscarinic receptor stimulation increases inositol-phospholipid metabolism and inhibits cyclic AMP accumulation in PC12 cells. 254 58

In the presence of Ro 20-1724, a selective inhibitor of cyclic nucleotide phosphodiesterase, carbamylcholine increases cAMP and cGMP levels in human thyroid cells in primary culture. The increase of cAMP exhibited at concentrations of carbamylcholine between 10 fM and 10 pM, is dose- and time-dependent, it is maximum after 30 min and is abolished after 60 min. At higher carbamylcholine concentration (10 microM), cAMP increases rapidly, becoming maximum after 15 min, but returns to unstimulated values after 30 min. The increase of cGMP is also dose-dependent (0.1 nM-10 microM); it reaches the maximum after 30 min and returns to unstimulated values after 120 min. A significant increase of phosphodiesterase activity is observed at 10 microM carbamylcholine. Atropine, a muscarinic receptor antagonist, blocks carbamylcholine effects on both cAMP and cGMP production without affecting the thyrotropin-induced cAMP accumulation. Hexamethonium, a nicotinic receptor antagonist does not affect the cholinergic effects. In the presence of Ro 20-1724, 10 microM carbamylcholine significantly inhibits the effect of thyrotropin on cAMP production, while the combined addition of low doses of carbamylcholine and thyrotropin (0.1 nM and 10 pM, respectively) results in an additive effect on cAMP levels. Inhibition of thyrotropin activity on cAMP production, similar to that exerted by 10 microM carbamylcholine is produced by increasing free intracellular calcium; this inhibition is relieved by using a calmodulin-sensitive phosphodiesterase inhibitor, M and B 22948 at 50 microM dose. High concentrations (10 microM) of carbamylcholine increase the adenylate cyclase activity, without any significant effect on the thyrotropin-induced activation of the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cholinergic control of cyclic nucleotide metabolism in human thyroid cells. 282 57

The thyroid tissue is innervated by cholinergic and VIPergic nerves. The present study investigated the possible interactions of cholinergic agents with VIP-induced cAMP accumulation and thyroid hormone release in vitro. Carbamylcholine (Cch), acting through the muscarinic receptor increases cellular cGMP content in cultured human thyroid cells incubated with a phosphodiesterase inhibitor. Cch (10 microM) inhibits cellular cAMP accumulation and thyroxine (T4) release induced by vasoactive intestinal peptide (VIP), with or without a phosphodiesterase inhibitor. Cch (10 microM) inhibits 8-bromo-cAMP-induced T4 release from human thyroid slices. 8-Bromo-cGMP inhibits VIP-induced T4 release from human thyroid slices, only in cells incubated without the phosphodiesterase inhibitor. The results indicate that interactions between VIPergic and cholinergic receptors may be of importance in human thyroid cell.
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PMID:Interaction of VIPergic and cholinergic receptors in human thyroid cell. 282 44

Changes in cyclic AMP concentrations were studied in intact PC12 pheochromocytoma cells exposed to a variety of treatments. A marked increase was triggered by N-(L-2-phenylisopropyl)adenosine, the activator of an adenosine receptor, whereas a decrease (observed even after phosphodiesterase blockade) was induced by carbachol, working through a muscarinic receptor inhibited by the selective muscarinic blocker pirenzepine, only at high concentration (Ki 450 nM). A decrease in cyclic AMP was also induced by clonidine, an alpha 2-adrenergic-receptor agonist. Both the alpha 2-adrenergic and the muscarinic inhibitions were prevented by pretreatment of the cells with pertussis toxin, and were unaffected by the phorbol ester 12-O-tetradecanoylphorbol 13-acetate. The latter drug caused a decrease in the resting cyclic AMP concentrations, and a potentiation of the increase induced by adenosine-receptor activation. Except for clonidine, all these treatments were found to be effective in both growing PC12 cells and, although to a smaller degree, in cells that had stopped growing and had acquired a neuron-like phenotype after prolonged treatment with nerve growth factor (NGF). Neither forskolin (a direct activator of adenylate cyclase) nor the activation of adenosine and alpha-adrenergic receptors was able to modify the resting cytosolic Ca2+ concentration [Ca2+]i in PC12 cells. Likewise, the K+-induced [Ca2+]i transients were unchanged after these treatments, whereas the transients induced by carbachol through the activation of a muscarinic receptor highly sensitive to pirenzepine were moderately potentiated by forskolin (and, to a lesser degree, by the adenosine analogue) and attenuated by clonidine. These results characterize in further detail the spectrum and the mutual interrelationships of the intracellular signals induced by receptor activation in PC12 cells, also as a function of the NGF-induced differentiation.
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PMID:Second-messenger generation in PC12 cells. Interactions between cyclic AMP and Ca2+ signals. 285 Jul 95

Balb/3T3 murine fibroblasts transformed by transfection with the EJ/T24 human bladder carcinoma oncogene were assayed in terms of adenylate cyclase response and hydrolysis of polyphosphoinositides dependent on specific agents. Transformed cells were much less responsive to beta-adrenergic agonists in rising cAMP than normal cells. They are instead much more sensitive to muscarinic receptor agonists, inducing a rapid intracellular accumulation of inositol phosphates. These results suggest that the functional alteration of the cell membrane caused by the product of the point mutated H-ras oncogene concerns in 3T3 fibroblasts both inhibitory and stimulatory effects, respectively on adenylate cyclase and phosphoinositide-phosphodiesterase.
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PMID:Transformation of BALB/3T3 cells with EJ/T24/H-ras oncogene inhibits adenylate cyclase response to beta-adrenergic agonist while increases muscarinic receptor dependent hydrolysis of inositol lipids. 286 65

The functionality of the alpha 1-, beta-adrenergic and muscarinic cholinergic binding sites of neuroblastoma B 50 is investigated under proliferating and differentiating conditions. In proliferating cells, the stimulation of the alpha 1-adrenergic and muscarinic cholinergic binding sites by their respective agonists causes an increase in both extracellular calcium association with the cells and phosphatidylinositol (PI) turnover; effects usually associated with functional receptors. When the cells are induced to differentiate morphologically with dibutyryl cyclic AMP (db-cAMP), extracellular calcium or a combination of both, the activity of the muscarinic receptor-coupled PI turnover is strictly correlated with the binding affinity of the receptor. This is not the case for the alpha 1-adrenergic receptor stimulation of PI turnover. The latter result, however, may be explained in terms of the intrinsic properties of the inducing agents used to cause neurite extension. The stimulation of the beta-adrenergic binding site with isoproterenol in proliferating cells, both with and without a phosphodiesterase inhibitor present, does not result in cellular cAMP accumulation. In morphologically differentiated cells, only the db-cAMP-induced state exhibits an increase in [3H]adenosine incorporation into cellular cAMP upon isoproterenol stimulation. This happens only in the presence of a phosphodiesterase inhibitor. The data presented in this study are discussed in terms of the affinity of the receptors for their respective ligands and in terms of the intrinsic properties of the inducing agents.
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PMID:Multiple types of neurotransmitter binding sites in the rat neuroblastoma B 50 cell line. II. Response of second messenger systems to physiological stimuli in proliferating and differentiated cells. 288 12

The occurrence of muscarinic cholinergic receptor-mediated activation of phosphodiesterase in 1321N1 cells does not represent an isolated phenomenon, since a similar response to cholinergic stimuli is observed in thyroid slices (45) and WI-38 fibroblasts (1,42). Both muscarinic-receptor-mediated inhibition of adenylate cyclase and activation of phosphodiesterase occur in WI-38 fibroblasts (42). Work currently under way in our laboratory is directed toward determining if a guanine nucleotide regulatory protein is involved in the activation of phosphodiesterase in these cells and whether common or separate populations of muscarinic receptors are coupled to these two mechanisms of cyclic AMP metabolism. The analysis of acute hormonal regulation of phosphodiesterase in intact cells is sufficiently complicated to have previously discouraged investigators from pursuing this question in mammalian tissues. The 1321N1 cell line provides a simple model system in which at least one mechanism of hormonal regulation of phosphodiesterase can be examined. In light of the widespread occurrence of muscarinic-receptor-mediated effects on Ca2+ mobilization, it would not be surprising to find that this mechanism represents an important part of cholinergic action in both the peripheral and central nervous systems. Indeed, this system could provide an important regulatory link between Ca2+ -mediated and cyclic-AMP-mediated events in target cells. The potential importance of such a mechanism also need not be restricted to the muscarinic receptor system, since any neurotransmitter or hormone receptor system coupled to events involved in Ca2+ mobilization might produce phenomena similar to that observed for muscarinic receptors in 1321N1 cells. Our studies emphasize that two mechanisms for regulation of cyclic AMP accumulation by muscarinic cholinergic receptors exist. The data to date suggest that separate receptor subtypes are involved in these mechanisms of cholinergic regulation and provide another biochemical basis whereby the well-known interaction of Ca2+ with the cyclic AMP system can be effected. Thus, identification of the molecular events involved in the regulation of PI turnover and its consequences may be crucial in defining the basis of this aspect of cholinergic action. In addition, more extensive analyses of the phosphodiesterase system using cell-free preparations have the potential of providing clues to the molecular basis of this mechanism.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Regulation of cyclic AMP metabolism by muscarinic cholinergic receptors. 298 97

The intracellular signals generated by carbachol activation of the muscarinic receptor [release of inositol phosphates as a consequence of phosphoinositide hydrolysis and rise of the cytosolic Ca2+ concentration ([Ca2+]i, measured by quin2)] were studied in intact PC12 pheochromocytoma cells that had been differentiated by treatment with nerve growth factor. When measured in parallel samples of the same cell preparation 30 s after receptor activation, the release of inositol trisphosphate and of its possible metabolites, inositol bis- and mono-phosphate, and the [Ca2+]i rise were found to occur with almost superimposable carbachol concentration curves. At the same time carbachol caused a decrease in the radioactivity of preloaded phosphatidylinositol 4,5-bisphosphate, the precursor of inositol trisphosphate. Neither the inositol phosphate nor the [Ca2+]i signal was modified by preincubation of the cells with either purified Bordetella pertussis toxin or forskolin, the direct activator of adenylate cyclase. Both signals were partially inhibited by dibutyryl cyclic AMP, especially when the nucleotide analogue was applied in combination with the phosphodiesterase inhibitors RO 201724 and theophylline. The latter drug alone profoundly inhibited the carbachol-induced [Ca2+]i rise, with only minimal effect on phosphoinositide hydrolysis. Because of the diverging results obtained with forskolin on the one hand, dibutyryl cyclic AMP and phosphodiesterase inhibitors on the other, the effects of the latter drugs are considered to be pharmacological, independent of the intracellular cyclic AMP concentration. Two further drugs tested, mepacrine and MY5445, inhibited phosphoinositide hydrolysis at the same time as the 45Ca2+ influx stimulated by carbachol. Taken together, our results concur with previous evidence obtained with permeabilized cells and cell fractions to indicate phosphatidylinositol 4,5-bisphosphate hydrolysis and [Ca2+]i rise as two successive events in the intracellular transduction cascade initiated by receptor activation. The strict correlation between the carbachol concentration curves for inositol trisphosphate generation and [Ca2+]i rise, and the inhibition by theophylline of the Ca2$ signal without major effects on inositol phosphate generation, satisfy important requirements of the abovementioned interpretation.
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PMID:Activation of muscarinic receptors in PC12 cells. Correlation between cytosolic Ca2+ rise and phosphoinositide hydrolysis. 301 59

Activation of muscarinic cholinergic receptors on 1321N1 human astrocytoma cells results in attenuation of cyclic AMP accumulation, apparently as a consequence of increases in phosphoinositide hydrolysis, Ca2+ mobilization, and the activation of a Ca2+ calmodulin-regulated phosphodiesterase. Preincubation of these cells with carbachol for 30-90 min resulted in a 15-30-fold shift to the right of the concentration effect curves for carbachol or methacholine for attenuation of cyclic AMP accumulation, with no change occurring in the maximal effect observed with either agonist. In contrast, preincubation with carbachol for 30-90 min resulted in an essentially complete loss of effects on cyclic AMP accumulation of the muscarinic receptor agonists oxotremorine, arecoline, and bethanechol. In contrast to carbachol and methacholine, oxotremorine, arecoline, and pilocarpine were much less effective inducers of desensitization. Inactivation of muscarinic receptors with propylbenzylcholine mustard, or preincubation of cells with 4 beta-phorbol 12 beta-myristate 13 alpha-acetate, which has been shown to markedly decrease the phosphoinositide response of 1321N1 cells to cholinergic agonists, produced differential effects on the cyclic AMP response to carbachol and oxotremorine that were similar to those observed after preincubation with carbachol. The data can be explained by the presence of "reserve" in the series of steps that result in muscarinic receptor-mediated activation of phosphodiesterase. That is, it is proposed that carbachol and methacholine mobilize much more Ca2+ than is necessary for maximal activation of phosphodiesterase, whereas oxotremorine and several other muscarinic receptor agonists do not.
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PMID:Receptor reserve in the calcium-dependent cyclic AMP response of astrocytoma cells to muscarinic receptor stimulation: demonstration by agonist-induced desensitization, receptor inactivation, and phorbol ester treatment. 301 76


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