Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cyclic nucleotide phosphodiesterase (PDE) activity and cAMP amounts were measured in mouse preimplantation embryos at the 1-cell, 2-cell, 8-cell/morula, and mid-blastocyst stages. PDE activity remained constant between the 1-cell and 2-cell stages. It decreased by the 8-cell stage and continued to decrease by the mid blastocyst stage to about 14% of the 1- and 2-cell values. By contrast, cAMP amounts remained essentially constant at 0.05 fmole/embryo (0.3 microM) from the 1-cell to the blastocyst stage and increased to 0.175 fmole in the fully expanded blastocyst that was close to hatching. Measurements of embryo volume indicated that intracellular volume remained essentially constant up to the blastocyst stage. The morphological changes in cell shape that accompany differentiation of the trophectoderm and that are coupled with blastocoel expansion decreased the intracellular volume. This decrease resulted in an increase in the cAMP concentration to about 0.4 microM by the mid-blastocyst stage. Previous studies indicate that either cAMP or TGF-alpha/EGF can stimulate the rate of blastocoel expansion. Although TGF-alpha/EGF can elevate cAMP levels in other cell types, TGF-alpha, at a concentration that maximally stimulates the rate of blastocoel expansion, did not elevate cAMP in blastocysts. Thus, it was unlikely that elevation of cAMP is the mechanism by which TGF-alpha stimulates the rate of blastocoel expansion.
Mol Reprod Dev 1992 Aug
PMID:Changes in cAMP phosphodiesterase activity and cAMP concentration during mouse preimplantation development. 132 7

The mechanism(s) underlying adenosine receptor-mediated modulation of cardiac cAMP levels has been investigated using detergent-permeabilized embryonic chick ventricular myocytes. The beta-adrenergic receptor agonist isoproterenol (ISO) stimulated adenylyl cyclase activity in detergent-permeabilized cells by 5-10-fold, with an EC50 value of 0.3 microM. Three adenosine receptor agonists, (R)-N6-phenylisopropyladenosine, N6-(3-iodo-4-aminobenzyl)adenosine, and 5'-N-ethylcarboxamidoadenosine, inhibited ISO (10 microM)-stimulated adenylyl cyclase activity in a concentration-dependent manner. The maximum inhibition of the ISO-stimulated adenylyl cyclase activity by (R)-N6-phenylisopropyladenosine (10 microM) was 30-40%. This inhibition was antagonized by the adenosine receptor antagonists xanthine amine congener and 8-cyclopentyl-1,3-dipropylxanthine and was abolished by pertussis toxin treatment, suggesting that the inhibition of adenylyl cyclase activity is mediated by A1 adenosine receptors acting via a pertussis toxin-sensitive guanine nucleotide-binding protein (G protein). Because the adenosine receptor agonists had no detectable effect on phosphodiesterase activity, the adenosine receptor-mediated inhibition of adenylyl cyclase activity appears to account for the cAMP-lowering effect of adenosine receptor agonists seen in intact cardiac myocytes. Moreover, two A1 adenosine receptor antagonists, 8-cyclopentyl-1,3-dipropylxanthine and 3-(4-amino)phenethyl-1-propyl-8-cyclopentylxanthine, stimulated basal adenylyl cyclase activity in the absence of an adenosine receptor agonist; this stimulation was abolished by pretreatment of the cells with pertussis toxin. We postulate that "precoupled" A1 adenosine receptor-G protein complexes, present in the cardiac myocytes, exert a tonic inhibitory influence on adenylyl cyclase activity and that some adenosine receptor antagonists remove this tonic inhibition by destabilizing these precoupled receptor-G protein complexes.
Mol Pharmacol 1992 Nov
PMID:Modulation of cardiac cyclic AMP metabolism by adenosine receptor agonists and antagonists. 133 65

Short-term exposure to okadaic acid (OA), a specific inhibitor of protein phosphatases 1 and 2A, induced resumption of meiosis, including metaphase spindle formation, in mouse oocytes treated with a phosphodiesterase inhibitor, while long incubations with OA arrested oocyte maturation at a step prior to spindle formation. To explore the basis for this difference, the overall patterns of protein synthesis and phosphorylation and the production of tissue-type plasminogen activator (tPA), the synthesis of which is induced after germinal vesicle breakdown (GVBD), were analyzed under various OA treatments. Short-term exposure to OA led to tPA production and did not greatly affect the maturation-associated changes in protein phosphorylation. By contrast, a long application of OA did not result in tPA production and induced more marked changes in protein phosphorylation. Microinjection into prophase oocytes of the product of the fission yeast gene p13suc1, known to inhibit p34cdc2 kinase activation and/or activity, prevented meiotic reinitiation. This effect was overcome by microinjection of OA, at concentrations higher than those required for induction of maturation in the absence of p13suc1. These observations suggest that inhibition of phosphatase 1 or 2A or both triggers meiotic resumption by acting at the same site or at a site proximal to the p13suc1-sensitive step of cdc2 kinase activation.
Mol Reprod Dev 1992 Nov
PMID:Okadaic acid and p13suc1 modulate the reinitiation of meiosis in mouse oocytes. 133 41

The possibility that vasoactive intestinal polypeptide (VIP) may facilitate the nicotine-mediated induction of adrenal medullary tyrosine hydroxylase (TH) was investigated with primary cultures (5-7 days in vitro) of bovine adrenal chromaffin (BAC) cells. Exposure of BAC cells to 100 microM nicotine led to only a marginal increase in the amount of TH mRNA, TH protein, and TH activity. VIP, alone or in the presence of a phosphodiesterase inhibitor, produced a marked increase in TH mRNA, TH protein, and TH activity. Moreover, VIP together with nicotine, at concentrations that alone were devoid of effect, increased the amount of TH mRNA and TH activity. A synergistic effect of VIP and nicotine on cAMP accumulation in BAC cells was also apparent. The marginal effects of large doses of nicotine on both cAMP accumulation and TH induction were blocked completely by hexamethonium but were also partially inhibited by the VIP antagonist [p-chloro-D-Phe6,Leu17]-VIP. Nicotine may, therefore, stimulate the release of VIP from cultured BAC cells and VIP, in turn, by increasing cAMP, may synergize with nicotine to enhance TH gene expression.
Mol Pharmacol 1992 Mar
PMID:Vasoactive intestinal polypeptide facilitates tyrosine hydroxylase induction by cholinergic agonists in bovine adrenal chromaffin cells. 134 40

Using rat hepatocytes we confirmed our previous results that glucagon and beta-adrenergic agonists increased the enzyme activity of alanine aminotransferase (AAT) and propranolol abolished their effects. Only the enzyme activity was measured and other parameters like quantity of the enzyme or activation due to modification were not looked for. As in perfusion experiment phenylephrine and phenoxybenzamine (alpha-agonist and alpha-antagonist respectively) also alpha-antagonist respectively) also increased the AAT activity in isolated rat hepatocytes and propranolol reversed these effects. The additive effect of glucagon and phenoxybenzamine on AAT was also persistent in hepatocyte system. Fructose-1:6-bisphosphatase (Fru-P2-ase), another key enzyme in gluconeogenic pathway, was elevated by glucagon and other beta-adrenergic agonists both in liver perfusion and isolated hepatocyte experiments and was brought back to the normal level by propranolol. In this case also only the enzyme activity was measured and no other parameters were looked for. Unlike AAT this enzyme was not stimulated by phenylephrine or phenoxybenzamine. But AAT and Fru-P2-ase activities were increased significantly by adenylate cyclase activators like fluoride or forskolin. Thus, it appears that the regulation of fru-P2-ase by glucagon is purely a b-receptor mediated process whereas AAT activation shows a mixed type of regulation where some well known alpha-agonist and antagonists are behaving as beta-agonists. Results further indicate the presence of phosphodiesterase in hepatocyte membrane which was stimulated by glucagon and brought back to the normal level by propranolol. The different adrenergic compounds stated above, not only modified the activity of the above two enzymes but also stimulated glucose production by hepatocytes from alanine which was in turn abolished by propranolol as well as amino oxyacetate (AOA), a highly specified inhibitor of AAT. This confirm the participation of AAT in gluconeogenesis from alanine in liver. Forskolin and fluoride also increased the glucose production from alanine and showed additive effects with glucagon, phenylephrine and phenoxybenzamine.
Mol Cell Biochem 1992 Aug 18
PMID:Effect of adrenergic agonists and antagonists on alanine amino transferase, fructose-1:6-bisphosphatase and glucose production in hepatocytes. 135 93

Cyclic AMP can profoundly influence the growth and differentiation of neuronal cells in culture. In this study, the relationship between this second messenger signal transduction pathway, cell differentiation, and the expression of a retinoid-responsive, thymosin beta-10 gene was examined. Thymosin beta-10 and cognate mRNA were expressed at high levels in actively proliferating rat B104 neuroblastoma cells cultured in medium containing 10% FCS. These cells were induced to differentiate in the presence of the cAMP analog N6, 2'-O-dibutyryladenosine 3':5'-cyclic monophosphate (Bt2-cAMP) (1 mM) and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) (100 microM). Expression of thymosin beta-10 mRNA was markedly inhibited (greater than 90% and 70%, respectively) by these compounds. Addition of sodium butyrate (NaB, 1 mM) indicated that at least part of the inhibitory actions of Bt2-cAMP were due to esterase-induced release of butyrate from this compound. Adenosine (50 microM), a metabolic precursor to endogenous cyclic AMP, also inhibited accumulation of thymosin beta-10 mRNA (to less than 70% of control levels). The inhibitory action of Bt2-cAMP upon thymosin beta-10 mRNA levels was time dependent; levels were inhibited by greater than 50% 24 hours after addition of the cAMP analog and by greater than 90% after 72 hours. Serum starvation (0.2% FCS for seven days) provoked a marked increase in neurite out-growth; this morphological change was also accompanied by a modest inhibition of thymosin beta-10 mRNA accumulation. These findings together with previous observations imply that both cyclic AMP-dependent and retinoid-responsive mechanisms coordinate thymosin beta-10 gene expression during neuroembryogenesis.
J Mol Neurosci 1992
PMID:Influence of cyclic AMP and serum factors upon expression of a retinoid-responsive gene in neuroblastoma cells. 137 94

Analysis of cyclic nucleotide phosphodiesterase (PDE) activity in cellular fractions from cultured rat pheochromocytoma (PC12) cells has shown that the predominant hydrolytic activity in both cytosolic and particulate compartments is characteristic of a PDE II, the cGMP-activatable family of PDE isozymes. Cytosolic PDE activity was purified to a high degree utilizing DE-52 anion exchange and cGMP-Sepharose affinity chromatographies. The physicochemical properties of PC12 PDE II were similar to those of PDE II isolated from particulate or soluble fractions of other tissues, including subunit molecular weight of approximately 102,000, activation of cAMP hydrolysis by cGMP, and positive cooperative kinetic behavior for cAMP and cGMP hydrolysis. The potential role of PDE II in regulating cAMP metabolism in intact PC12 cells was studied using an [3H]adenine prelabeling technique. Stimulation of PC12 cell adenosine receptors resulted in a 5-8-fold increase in cAMP accumulation. Removal of the adenosine stimulus by the addition of exogenous adenosine deaminase resulted in a rapid decay of cAMP to prestimulated basal levels within 2 min. Treatment of PC12 cells with atrial natriuretic factor or sodium nitroprusside caused 1) increased intracellular cGMP levels, 2) attenuation of adenosine-stimulated cAMP accumulation, and 3) increased rates of cAMP decay after removal of the adenosine stimulus. Treatment of PC12 cells with HL-725 (a potent inhibitor of isolated PDE II activity in vitro) caused 1) increased basal cAMP accumulation, 2) potentiation of adenosine-stimulated cAMP accumulation, and 3) retardation of the rate of cAMP decay after removal of the adenosine stimulus. HL-725 blocked both the attenuation of cAMP accumulation and the accelerated rate of cAMP decay observed with the cGMP-elevating agents. These results suggest that, in PC12 cells, drugs or hormones that inhibit PDE II or increase intracellular cGMP levels to activate PDE II can modulate cAMP metabolism by altering the catalytic status of the enzyme.
Mol Pharmacol 1991 Jun
PMID:Phosphodiesterase II, the cGMP-activatable cyclic nucleotide phosphodiesterase, regulates cyclic AMP metabolism in PC12 cells. 164 46

Cyclic AMP regulation by muscarinic and adenosine receptors was investigated in isolated canine ventricular myocytes. Both the muscarinic receptor agonist, carbachol, and the adenosine receptor agonist, phenylisopropyladenosine, decreased isoproterenol-stimulated cyclic AMP accumulation in a concentration-dependent manner. Carbachol was more potent than phenylisopropyladenosine and had a greater inhibitory effect. At 10(-6) M, carbachol reduced isoproterenol-stimulated cyclic AMP by 73 +/- 5% while 10(-3) M phenylisopropyladenosine was required to decrease cyclic AMP accumulation by 54 +/- 8%. Pretreatment of myocytes with pertussis toxin to inactivate the inhibitory guanine nucleotide binding protein, Gi, completely abolished the effect of phenylisopropyladenosine to reduce cyclic AMP stimulation. In comparison, pertussis toxin treatment blunted the response to carbachol and shifted the dose-effect curve to the right but did not eliminate the inhibitory action of carbachol. In toxin-treated myocytes, 10(-3) M carbachol produced a 26 +/- 6% reduction of isoproterenol-induced cyclic AMP accumulation. This pertussis toxin-insensitive action of carbachol was antagonized by atropine and pirenzepine and was prevented when either of two different phosphodiesterase inhibitors. RO-20-1724 or isobutylmethylxanthine, was included in the incubation medium. The results indicate that adenosine receptor-mediated inhibition of hormone-stimulated cyclic AMP accumulation in ventricular myocytes occurs by a single, Gi-dependent mechanism while muscarinic inhibition appears to involve both Gi-dependent and Gi-independent mechanisms. The Gi-independent mechanism may reflect enhanced phosphodiesterase activity which results from the activation of muscarinic receptors.
J Mol Cell Cardiol 1991 Feb
PMID:Differential effect of pertussis toxin on adenosine and muscarinic inhibition of cyclic AMP accumulation in canine ventricular myocytes. 164 26

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+/calmodulin-dependent cyclic nucleotide (AMP) phosphodiesterase activity in rat liver cytosol was investigated. The addition of Ca2+ (50 microM) and calmodulin 160 U/ml in the enzyme reaction mixture caused a significant increase in cyclic AMP phosphodiesterase activity. This increase was inhibited by the presence of regucalcin (0.5-3.0 microM); the inhibitory effect was complete at 1.0 microM. Regucalcin (1.0 microM) did not have an appreciable effect on basal activity without Ca2+ and calmodulin. The inhibitory effect of regucalcin was still evident even at several fold higher concentrations of calmodulin (160-480 U/ml). However, regucalcin (1.0 microM) did not inhibit Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity in the presence of 100 and 200 microM Ca2+ added. Meanwhile, Cd2+ (25-100 microM)-induced decrease in Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity was not reversed by the presence of regucalcin (1.0 microM). The present results suggest that regucalcin can regulate Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity due to binding Ca2+ in liver cells.
Mol Cell Biochem 1991 Jul 24
PMID:Inhibitory effect of calcium-binding protein regucalcin on Ca2+/calmodulin-dependent cyclic nucleotide phosphodiesterase activity in rat liver cytosol. 165 6

Impaired inotropic responsiveness to isoproterenol stimulation has been reported in the hypertrophied hearts of spontaneously hypertensive rats and renal hypertensive rats. This study was carried out in order to investigate the possibility that a defect in cyclic AMP production by cardiac myocytes is responsible for the impaired inotropic responsiveness of these hearts. Basal and isoproterenol stimulated cyclic AMP levels were measured in ventricular myocytes isolated from hypertrophied rat hearts. Cyclic AMP accumulation was also measured in the presence of isobutyl-methyl-xanthine, a phosphodiesterase inhibitor, and the results were compared to the appropriate controls. In the spontaneously hypertensive rat, no changes were detected in the basal or isoproterenol stimulated cyclic AMP formation. This suggests that the biochemical alterations leading to a diminished inotropic response in this model of cardiac hypertrophy involve abnormalities in mechanisms other than cyclic AMP production. In the renal hypertensive rat, basal and isoproterenol stimulated cyclic AMP levels were significantly depressed as compared to controls. This suggests that abnormalities in the signal transduction mechanism and formation of cyclic AMP are, at least in part, responsible for the impaired inotropic responsiveness seen in this model. These results confirm that cardiac hypertrophy is a heterogeneous process. Reduced inotropic responsiveness to isoproterenol stimulation in the hypertrophied hearts of the SHR and the RHR, both models of pressure overload hypertrophy, involve different biochemical alterations. Results of this study suggest that the physiologic response of cardiac hypertrophy may not be as important as the underlying cause of hypertrophic stimuli in determining the pathophysiological consequences.
J Mol Cell Cardiol 1991 Jun
PMID:Cyclic AMP in myocytes isolated from hypertrophied rat hearts. 165 43


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>