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At least 271 records · Page 15Linked to original sources
PubMed1979

Role of calcium dependent regulator protein (CDR) in inhibition of 3',5'-c AMP-phosphodiesterase by influenza virus. I. Isolation and purification of CDR and CDR-dependent 3',5'-c' AMP-phosphodiesterase from chick embryos.

Calcium-dependent regulator protein (CDR) and CDR-dependent 3',5'-c AMP-phosphodiesterase were isolated and partially purified from 12-day chick embryos. Some basic properties of the preparations obtained were described. Native (infectious) but not noninfectious (heat-inactivated) influenza virus in the presence of CDR and ATP reduced the activity of CDR-dependent phosphodiesterase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

The role of cyclic AMP in modulating cytotoxic T lymphocytes. II. Sequential changes during culture in responsiveness of cytotoxic lymphocytes to cyclic AMP-active agents.

Agents that increase cyclic AMP (cAMP) levels inhibited the activity of cytotoxic T lymphocytes (CTL) obtained from spleens of mice immunized with allogeneic cells. Cultured CTL, however, were desensitized to cAMP-active agents, in that the capacity of these agents to inhibit the activity of cultured CTL was markedly reduced. The capacity to inhibit CTL activity was reduced more rapidly for some agents than for others; the percent inhibition by histamine and PGE2 was reduced after 4 hr and was reduced more than 20% after 24 hr, whereas the percent inhibition by dibutyryl cAMP, theophylline, and cholera enterotoxin was reduced less than 6% after 24 hr, and was reduced significantly only after 48 hr. Culture in the presence of antigen accelerated desensitization to the latter three agents. CTL populations were also tested for their capacity to increase cAMP levels in response to agonists. The capacity of histamine to increase cAMP levels of the CTL was lost within 4 hr (i.e., as rapidly as its capacity to inhibit CTL activity) and was never restored, whereas the capacity of PGE2 to increase cAMP levels persisted throughout culture. These results suggest that culture induces multiple alterations in cAMP metabolism of CTL. These alterations, which result in dissociation of CTL activity from cAMP-mediated regulatory steps, may include loss of histamine receptors and/or histamine receptor-adenylate cyclase coupling, and also loss of one or more biochemical reactions that link elevated cAMP levels to inhibition of lysis.

Animals↗
PubMed1999

Synergistic activation of mitogen-activated protein kinase by cyclic AMP and myeloid growth factors opposes cyclic AMP's growth-inhibitory effects.

Colony-stimulating factors (CSFs) promote the proliferation, differentiation, commitment, and survival of myeloid progenitors, whereas cyclic AMP (cAMP)-mediated signals frequently induce their growth arrest and apoptosis. The ERK/mitogen-activated protein kinase (MAPK) pathway is a target for both CSFs and cAMP. We investigated how costimulation by cAMP and colony-stimulating factor-1 (CSF-1) or interleukin-3 (IL-3) modulates MAPK in the myeloid progenitor cell line, 32D. cAMP dramatically increased ERK activity in the presence of CSF-1 or IL-3. IL-3 also synergized with cAMP to activate ERK in another myeloid cell line, FDC-P1. The increase in ERK activity was transmitted to a downstream target, p90(rsk). cAMP treatment of 32D cells transfected with oncogenic Ras was found to recapitulate the superactivation of ERK seen with cAMP and CSF-1 or IL-3. ERK activation in the presence of cAMP did not appear to involve any of the Raf isoforms and was blocked by expression of dominant-negative MEK1 or treatment with a MEK inhibitor, PD98059. Although cAMP had an overall inhibitory effect on CSF-1-mediated proliferation and survival, the inhibition was markedly increased if ERK activation was blocked by PD98059. These findings suggest that upregulation of the ERK pathway is one mechanism induced by CSF-1 and IL-3 to protect myeloid progenitors from the growth-suppressive and apoptosis-inducing effects of cAMP elevations.

Animals↗
PubMed2004

Transcriptional activation of phosphodiesterase 7B1 by dopamine D1 receptor stimulation through the cyclic AMP/cyclic AMP-dependent protein kinase/cyclic AMP-response element binding protein pathway in primary striatal neurons.

Phosphodiesterase (PDE) 7B, a cAMP-specific PDE which is dominantly expressed in striatum, is expected to be involved in dopaminergic signaling in striatal neurons. Here we show, for the first time, the involvement of the dopaminergic signaling pathway in transcriptional activation of rat PDE7B in primary striatal culture. RT-PCR analysis revealed that dopamine, D1 agonist, forskolin and 8-Br-cAMP stimulation potentiated PDE7B transcription in striatal neurons, while D2 agonist failed to activate the PDE7B transcription. Pre-treatment with D1 antagonist abolished the dopamine- or D1 agonist-induced transcriptional activation of PDE7B. The activation of PDE7B transcription by these stimulators was completely ablated by pre-treatment of the cells with a cAMP-dependent protein kinase inhibitor, H-89. RT-PCR using splice variant-specific primers revealed that transcription of PDE7B1, but not of other splice variants, was activated by D1 agonist. We determined the putative transcription start site of PDE7B1, a brain-specific splice variant of PDE7B, by 5'-RACE and identified a promoter region of PDE7B1. Sequence analysis of the PDE7B1 promoter revealed the presence of a canonical cAMP-response element at 166 bp upstream of the putative transcription start site. The cAMP-responsiveness of the PDE7B1 promoter was demonstrated by functional promoter analysis using the luciferase reporter system. Deletion and mutation of the cAMP-response element site in the PDE7B1 promoter abolished the forskolin-induced activation of the PDE7B1 promoter activity. Electrophoretic mobility shift assay showed the binding of cAMP-response element binding protein to the PDE7B1 promoter. These data demonstrate the dopamine D1 receptor-mediated transcriptional activation of PDE7B through the cAMP/cAMP-dependent protein kinase/cAMP-response element binding protein pathway in striatal neurons.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1999

Protection by a cyclic AMP-specific phosphodiesterase inhibitor, rolipram, and dibutyryl cyclic AMP against Propionibacterium acnes and lipopolysaccharide-induced mouse hepatitis.

OBJECTIVE AND DESIGN: To study the effect of cellular cAMP-increasing agents on Propionibacterium acnes (P. acnes) and lipopolysaccharide (LPS)-induced mouse hepatitis. MATERIAL: Male BALB/c mice were used. Macrophages/Kupffer cells isolated from P. acnes-primed murine liver were used for the in vitro study. TREATMENT: Type IV phosphodiesterase (PDE)-specific inhibitor, rolipram, was administered (10, 30 mg/kg, p. o.). Dibutyryl cyclic AMP (dbcAMP) was injected (10, 100 mg/kg, i.p.) into the mice. METHOD: Plasma TNFalpha estimated by the use of an L-929 cell cytotoxic assay and plasma transaminase activities were measured for the in vivo study. The LPS-induced production of TNFalpha in vitro from the cultured macrophage/Kupffer cells was determined by ELISA. RESULTS: Rolipram suppressed the elevation of plasma transaminases induced by injection of LPS, and dbcAMP had a tendency to suppress them. Both agents attenuated the LPS-induced release of TNFalpha in vivo, and suppressed the TNFalpha production from the cultured macrophage/Kupffer cells. CONCLUSIONS: These results suggest that rolipram and dbcAMP have potential to inhibit TNFalpha production from activated macrophage/Kupffer cells, and it may be partially involved in the protecting effect in the P. acnes/LPS hepatitis model.

Animals↗
PubMed1995

Effects of dibutyryl cyclic AMP and retinoic acid on the differentiation of dopamine neurons: prevention of cell death by dibutyryl cyclic AMP.

Immature neurons, including fetal and tumoral cells, are used for investigating neuronal differentiation in vitro. The human neuroblastoma cell line NB69 could be induced to differentiate to dopamine or acetylcholine neurons by different compounds, including neurotrophins and activators of the protein kinases. In these NB69 cells dibutyryl cyclic AMP (dbcAMP) at 2 mM reduced the division rate and increased the levels of catecholamines, tyrosine hydroxylase (TH) activity, and monoamine oxidase activity. The dbcAMP also increased cell size, dendritic arborization, density of the sites for high-affinity dopamine uptake, and activity of choline acetyltransferase. In fetal rat midbrain neurons treatment with dbcAMP increased the levels of dopamine and the number of TH-immunoreactive neurons in the culture. When embryonic day 14 fetal midbrain neurons, previously exposed to 1 microM retinoic acid (a compound that severely reduces the number of fetal midbrain dopamine neurons), were treated with dbcAMP, the levels of dopamine and the number of TH-immunoreactive cells returned to normal levels. This suggests that dbcAMP induces the differentiation to dopamine neurons of quiescent progenitor or facilitates expression of the dopamine phenotype in immature neurons. Therefore, dbcAMP not only differentiates uncommitted immature dopamine neurons, but also reverses the antidopaminergic effects of retinoic acid. These properties of dbcAMP could be of therapeutic value in Parkinson's disease.

Alprostadil↗
PubMed1990

Glucose-induced hyperaccumulation of cyclic AMP and defective glucose repression in yeast strains with reduced activity of cyclic AMP-dependent protein kinase.

Addition of glucose or related fermentable sugars to derepressed cells of the yeast Saccharomyces cerevisiae triggers a RAS-mediated cyclic AMP (cAMP) signal that induces a protein phosphorylation cascade. In yeast mutants (tpk1w1, tpk2w1, and tpk3w1) containing reduced activity of cAMP-dependent protein kinase, fermentable sugars, as opposed to nonfermentable carbon sources, induced a permanent hyperaccumulation of cAMP. This finding confirms previous conclusions that fermentable sugars are specific stimulators of cAMP synthesis in yeast cells. Despite the huge cAMP levels present in these mutants, deletion of the gene (BCY1) coding for the regulatory subunit of cAMP-dependent protein kinase severely reduced hyperaccumulation of cAMP. Glucose-induced hyperaccumulation of cAMP was also observed in exponential-phase glucose-grown cells of the tpklw1 and tpk2w1 strains but not the tpk3w1 strain even though addition of glucose to glucose-repressed wild-type cells did not induce a cAMP signal. Investigation of mitochondrial respiration by in vivo 31P nuclear magnetic resonance spectroscopy showed the tpk1w1 and tpk2w1 strains, to be defective in glucose repression. These results are consistent with the idea that the signal transmission pathway from glucose to adenyl cyclase contains a glucose-repressible protein. They also show that a certain level of cAMP-dependent protein phosphorylation is required for glucose repression. Investigation of the glucose-induced cAMP signal and glucose-induced activation of trehalase in derepressed cells of strains containing only one of the wild-type TPK genes indicates that the transient nature of the cAMP signal is due to feedback inhibition by cAMP-dependent protein kinase.

Adenosine Triphosphate↗
PubMed1982

[Affinity modification of heavy meromyosin and subfragment 1 by mixed anhydrides of [14C] AMP, epsilon AMP and mesitylene carboxylic acid].

Using mixed anhydride of AMP and mesitylene carboxylic acid carrying a fluorescent or radioactive label, it was found that the previously established irreversible inhibition of myosin ATPase is a result of protein covalent binding to the nucleotide residue of the inhibitor. The stoichiometry of the affinity labelling of heavy meromyosin is 1 mole of nucleotide residue of mixed anhydride per 1 mole of protein, that of subfragment 1-0.5 mole per 1 mole of protein. The lack of irreversible inhibition of the ATPase activity of subfragment 1 is suggestive of an existence of a regulatory substrate-binding site in the myosin molecule.

Adenosine Monophosphate↗
PubMed2004

Antipsychotics regulate cyclic AMP-dependent protein kinase and phosphorylated cyclic AMP response element-binding protein in striatal and cortical brain regions in mice.

Adenosine 3',5'-monophosphate (cAMP) and cAMP-dependent protein kinase (PKA) signaling have been implicated in antipsychotic drug action. This study examines the effects of acute antipsychotic treatment using typical (haloperidol) and atypical (olanzapine) agents on cAMP signaling in dorsal striatum, nucleus accumbens and medial prefrontal cortex in mice. PKA catalytic subunit (PKA-c) and phosphorylated cAMP response element-binding protein (pCREB) levels were measured to evaluate antipsychotic drug effects. Nuclear PKA-c levels increased in the dorsal striatum after haloperidol and olanzapine treatment. In medial prefrontal cortex, olanzapine produced dose-dependent decreases in PKA-c and pCREB levels. The differential effects of typical versus atypical antipsychotic agents on PKA and pCREB in striatal and cortical regions illustrate the diverging actions of these agents on cAMP pathways.

Animals↗
PubMed1995

Norepinephrine stimulation of pineal cyclic AMP response element-binding protein phosphorylation: primary role of a beta-adrenergic receptor/cyclic AMP mechanism.

Norepinephrine (NE) regulates melatonin production and many other aspects of pineal function through actions involving cAMP. In the present study the effects of NE on the phosphorylation of the cAMP response element-binding protein (CREB) were studied to determine whether CREB phosphorylation might be involved in cAMP signal transduction in this tissue. CREB was detected using gel mobility-shift analysis with the radiolabeled Ca2+/cAMP response element of the c-fos promoter. CREB phosphorylation was estimated in the gel mobility-shift assay using an antiserum specific for phosphorylated CREB. This antiserum generates a supershifted CREB signal with protein extracts obtained from glands treated with NE (EC50 approximately equal to 10 nM) in organ culture, demonstrating that NE stimulates CREB phosphorylation. CREB phosphorylation peaks 30-45 min after NE treatment is initiated and then gradually returns to base-line values. Pharmacological studies show that NE-stimulated CREB phosphorylation is mediated primarily through beta 1-adrenergic receptor-stimulated increases in cAMP. Activation of alpha 1-adrenergic receptors, which is known to elevate the intracellular free Ca2+ concentration, does not cause CREB phosphorylation. However, it is possible to produce CREB phosphorylation with certain pharmacological agents that elevate the intracellular free Ca2+ concentration. In vivo studies show that CREB phosphorylation can be induced by treatment with isoproterenol (1 mg/kg), demonstrating that phosphorylation of pineal CREB occurs in intact animals. These studies indicate that cAMP-dependent CREB phosphorylation could play a role in the adrenergic regulation of gene expression in pinealocytes.

Animals↗
PubMed1984

On the action of the cyclic AMP-cyclic AMP receptor protein complex at the Escherichia coli lactose and galactose promoter regions.

Using DNase footprinting and transcription assays in vitro we have probed the effect of the cAMP-cAMP receptor protein complex (cAMP-CRP) on the positioning of RNA polymerase and on the location of the transcription start point at the Escherichia coli gal and lac operon regulatory regions. In both cases, RNA polymerase can form two alternative complexes which promote transcription from two different start points, S1 and S2: pre-incubation of promoter DNA with cAMP-CRP results in a shift of the transcription start from S2 to S1 and in an increase in the rate of open complex formation. Moreover, the rate of formation of each heparin-resistant complex parallels the establishment of the corresponding footprint, showing that the stable binding corresponds to open complex formation. We show that, in the case of gal, RNA polymerase, which is bound so as to transcribe from S2, cannot be diverted to S1 by subsequent addition of cAMP-CRP. In contrast, in the case of lac, when cAMP-CRP is added after RNA polymerase, complexes which initiate transcription at S2 are rapidly converted to complexes which initiate at S1. Finally, we present data which suggest that protein-protein interactions are essential for CRP-induced activation at both the lac and gal promoters.

Base Sequence↗
PubMed1988

Cell cycle phase in Dictyostelium discoideum is correlated with the expression of cyclic AMP production, detection, and degradation. Involvement of cyclic AMP signaling in cell sorting.

Cell cycle phase in Dictyostelium is correlated with a different preference for either spore or stalk differentiation. Cells which start development early in the cell cycle (E cells) exhibit a strong tendency to sort to the prestalk region of slugs, while late cell cycle cells (L cells) sort to the prespore region. We investigated the expression of the cAMP chemotactic system during development of synchronized E and L cells and found that E cells exhibit cAMP-binding activity, cell surface cAMP-phosphodiesterase (mPDE) activity, and the ability to relay cAMP signals at least 2 hr earlier and to higher levels than L cells. We hypothesize that E cells are prestalk sorters because they are the first to initiate aggregation centers and respond most effectively with chemotaxis and signal relay.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

Cooperative non-specific DNA binding of the N-terminal core of the cyclic AMP receptor protein of Escherichia coli and its modulation by cyclic AMP.

The non-specific DNA binding of CRP and its N-terminal core, alpha CRP, to a 298 base pair DNA fragment, in the presence and absence of cAMP, has been studied using the nitrocellulose filter binding technique and analysed quantitatively using the theory of Clore et al. [J. Mol. Biol. (1982) 155, 447-466]. It is shown that both CRP and alpha CRP bind cooperatively to DNA. At an ionic strength of 100 mM and pH 7.5, the intrinsic equilibrium association constant for the binding of alpha CRP to DNA is approximately 10-times smaller than that for CRP, but the cooperativity parameter is approximately 17-times larger for alpha CRP than CRP. cAMP exerts its effect solely on the intrinsic equilibrium constant and does not alter the cooperativity. In the case of alpha CRP, cAMP reduces the intrinsic equilibrium association constant by a factor of 3, in contrast to the case of CRP where cAMP increases it by a factor of 3. The possible location of the DNA binding site present in the N-terminal core of CRP is discussed in the light of crystallographic data on the cAMP . CRP complex [McKay et al. (1982) J. Biol. Chem. 257, 9518-9524].

Base Composition↗