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At least 433 records · Page 24Linked to original sources
PubMed1985

Effect of cold exposure on liver and muscle cAMP content and cAMP phosphodiesterase activity.

Adenosine 3',5'-cyclic monophosphate (cAMP) concentration and 3',5'-cyclic-nucleotide phosphodiesterase (PDE) activity were measured in skeletal muscle, heart, and liver of rats exposed to 1, 3, 5, and 7 days of cold. Cyclic nucleotide concentration increased in fast-twitch red muscle at the same time that PDE activity was decreasing. Nucleotide concentration and enzyme activity of slow-twitch red muscle were not altered by the cold exposure. The PDE activity of fast-twitch white muscle was elevated approximately 50% above control after 1 and 3 days of cold exposure. By the 5th day in the cold, white muscle PDE activity had returned to control levels and remained there through the 7th day of experimentation. cAMP concentration in hearts of cold-exposed rats was significantly (P less than 0.01) elevated above control at all time points measured. Myocardial PDE activity was elevated above control (P less than 0.05) at 1 and 3 days of cold exposure but returned to control levels by the 5th day in the cold. Hepatic cAMP and PDE activity were elevated above control at all time points analyzed. These data suggest that changes in cyclic nucleotide metabolism play a role in attaining homeostasis during acute cold exposure.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1982

Effect of high level bovine parathyroid extracts on serum PTH, cAMP and urinary cAMP, Na+, and uric acid in stone-forming patients.

Patients with a history of idiopathic calcium oxalate stones, but without current stone formation, show distinctly higher levels of serum cAMP (cyclic adenosine 3',5'-monophosphate) after rapid injection of an extreme concentration of parathyroid extract (PTE). Extreme parathyroid hormone (PTH) levels, as induced by rapid injection of biologically active bovine PTEs, significantly affect the renal generation of cAMP and the elimination of electrolytes in a healthy control group. The stimulated increase of urinary cAMP, sodium, potassium, calcium and phosphate are observed to return to normal levels 120 min after extreme PTE injections for both groups studied.

Calcium↗
PubMed2005

Coordinate regulation of basal and cyclic 5'-adenosine monophosphate (cAMP)-activated expression of human chorionic gonadotropin-alpha by Ets-2 and cAMP-responsive element binding protein.

Ets-2 controls the activities of many genes characteristically up-regulated in trophoblast. One apparent exception has been the gene for the human chorionic gonadotropin subunit alpha (hCGalpha). Here, we show that the hCGalpha gene contains two overlapping Ets binding sites adjacent to an activator protein-1-like site in its proximal promoter. Transactivation by Ets-2 is susceptible to truncation and mutation of these sites, which bind Ets-2 during in vitro mobility shift assays, as well as in vivo as determined by chromatin immunoprecipitation in choriocarcinoma cells. Knockdown of Ets-2 with short interfering RNA decreases both promoter activity and synthesis of hCGalpha. Ets-2 acts in combination with the protein kinase A (PKA) signal transduction pathway to activate the hCGalpha promoter expression. Mutation of the Ets-2 binding sites dramatically reduces up-regulation by PKA, whereas mutations within the two cAMP-responsive elements abolish responsiveness of the promoter to Ets-2. cAMP-responsive element binding protein (CREB) and Ets-2 form a complex that can be coimmunoprecipitated from choriocarcinoma cells, and association of CREB and Ets-2 is increased by activation of PKA. Regulation of hCGalpha subunit gene activity by cAMP involves the binding of CREB and Ets-2 to discrete elements in the promoter as well as a physical interaction between the two proteins. We propose that regulation of hCGalpha by Ets-2 and CREB enables coordinated expression of hCGalpha with its partner hCGbeta subunit.

Base Sequence↗
PubMed1999

Inducible binding of cyclic adenosine 3',5'-monophosphate (cAMP)-responsive element binding protein (CREB) to a cAMP-responsive promoter in vivo.

In general, DNA-binding factors that activate gene transcription are thought to do so via reversible interaction with DNA. However, most studies, largely performed in vitro, suggest that the transcriptional activator, cAMP response element-binding protein (CREB), is exceptional in that it is constitutively bound to the promoter, where its phosphorylation leads to the recruitment of CREB-binding protein (CBP) to form a CREB/CBP/promoter complex. We have studied how CREB interacts with DNA in vivo to regulate the cAMP-responsive gene encoding human CRH (hCRH). Protein-DNA complexes were cross-linked in cells expressing the endogenous hCRH gene by exposure to a 10 nsec pulse of high-energy UV-laser light, followed by immunoaffinity purification of CREB-DNA complexes. Binding of CREB to a fragment of the hCRH promoter containing a canonical, functional cAMP response element was absent in untreated cells, but was specifically induced after activation of the protein kinase A pathway with forskolin. These data indicate that, in vivo, CREB, like the majority of other DNA-binding transcriptional activators, undergoes signal-mediated promoter interaction.

Binding Sites↗
PubMed1992

Identification and characterization of the GC-rich and cyclic adenosine 3',5'-monophosphate (cAMP)-inducible promoter of the type II beta cAMP-dependent protein kinase regulatory subunit gene.

A rat genomic clone containing 4.5 kilobases of 5'-flanking DNA and the first exon of the type II beta regulatory subunit (RII beta) of cAMP-dependent protein kinase was isolated, restriction mapped, and sequenced. The proximal 400-basepair promoter region was GC rich, lacked TATA/CAAT box motifs, and initiated transcription at multiple sites. Bandshifting and DNase-I footprinting experiments using this region of the RII beta promoter detected several related specific DNA-protein complexes formed using crude and fractionated nuclear extracts from rat ovary, brain, adrenal gland, and liver. All binding in these experiments mapped to a domain within the same region found to confer cAMP inducibility to a chloramphenicol acetyltransferase (CAT) reporter gene when transfected into primary cultures of rat granulosa cells. Although GC boxes (putative SP1-binding sites) and activator protein-2 (AP-2) elements were present in this functional region, and although expression vectors containing AP-2 sites conferred high levels of cAMP regulation of the CAT gene in cultured ovarian cells, neither the GC boxes nor the AP-2 sites were protected by footprint analyses or required for band shift activity of nuclear extract protein. These known regulatory elements, therefore, may be involved in functional activity of the RII beta promoter, but additional cis-acting DNA and trans-acting factors (yet to be characterized) also appear to interact with the functional promoter of the RII beta gene and regulate the hormone-specific expression of the A-kinase subunit in ovarian and neuronal cells.

Amino Acid Sequence↗
PubMed2006

The Dunce cAMP phosphodiesterase PDE-4 negatively regulates G alpha(s)-dependent and G alpha(s)-independent cAMP pools in the Caenorhabditis elegans synaptic signaling network.

Forward genetic screens for mutations that rescue the paralysis of ric-8 (Synembryn) reduction-of-function mutations frequently reveal mutations that cause hyperactivation of one or more components of the G alpha(s) pathway. Here, we report that one of these mutations strongly reduces the function of the Dunce cAMP phosphodiesterase PDE-4 by disrupting a conserved active site residue. Loss of function and neural overexpression of PDE-4 have profound and opposite effects on locomotion rate, but drug-response assays suggest that loss of PDE-4 function does not affect steady-state acetylcholine release or reception. Our genetic analysis suggests that PDE-4 regulates both G alpha(s)-dependent and G alpha(s)-independent cAMP pools in the neurons controlling locomotion rate. By immunostaining, PDE-4 is strongly expressed throughout the nervous system, where it localizes to small regions at the outside boundaries of synaptic vesicle clusters as well as intersynaptic regions. The synaptic subregions containing PDE-4 are distinct from those containing active zones, as indicated by costaining with an antibody against the long form of UNC-13. This highly focal subsynaptic localization suggests that PDE-4 may exert its effects by spatially regulating intrasynaptic cAMP pools.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2003

Inducible cAMP early repressor, an endogenous antagonist of cAMP responsive element-binding protein, evokes neuronal apoptosis in vitro.

Active CREB (cAMP responsive element-binding protein) transcription factor is crucial for neuronal survival. Several members of the CREM/ICER (cAMP responsive element modulator/inducible cAMP early repressor) protein family may act as endogenous CREB antagonists. However, their involvement in a process of programmed cell death remains unexplored. Here we report that ICER may play such a role in neuronal apoptosis because it is upregulated in apoptotic neurons in vitro, and overexpression of ICER, delivered in adenoviral vector, evokes programmed cell death of three different kinds of cultured neurons, namely those derived from hippocampal dentate gyrus, cerebral cortex, and superior cervical ganglion. Reporter gene assay with a promoter containing a CREB-responsive sequence revealed a decrease in both basal and induced CRE-dependent gene expression in neurons overexpressing ICER. Finally, the level of expression of the anti-apoptotic protein Bcl-2, a well known CREB target, was markedly diminished in ICER-treated neurons. We suggest that the naturally occurring CREB functional antagonist ICER may have a specific function in programmed cell death of neurons, probably by silencing the expression of anti-apoptotic genes.

Adenoviridae↗
PubMed1990

A DNA motif related to the cAMP-responsive element and an exon-located activator protein-2 binding site in the human tissue-type plasminogen activator gene promoter cooperate in basal expression and convey activation by phorbol ester and cAMP.

Tissue-type plasminogen activator (t-PA) gene expression is regulated by the tumor-promoting phorbol ester, phorbol-12-myristate 13-acetate (PMA), by cyclic AMP analogues, and the cAMP agonist, forskolin. Based on nuclear "run-on" transcription assays, t-PA expression is modulated by PMA on the level of transcription. 8-Bromo-cyclic AMP and forskolin do not induce t-PA gene transcription alone but act synergistically with PMA. These effects are confirmed by transient expression assays in HeLa cells employing deletion mutants of the t-PA gene promoter fused to the chloramphenicol acetyltransferase (CAT) reporter gene. Constitutive expression and most of the PMA-mediated induction requires sequences downstream of position -145. DNase I protection ("footprint") analysis of this region reveals two protein-binding sites: one between position -102 and -115, differing from the consensus sequence of the cAMP-responsive element (CRE) by the substitution of an adenine for a guanine in the middle of the core motif (TGACATCA), and another, located in the first exon (between position +60 and +74), displaying homology to the consensus sequence of the activator protein 2- (AP-2) binding site (CCCCACCCCC). Base substitutions in the core of either the CRE-like element or the AP-2 site suppress constitutive CAT expression by over 80%, whereas the relative PMA- and PMA plus cAMP-mediated responses are retained. CAT expression is below the detection limit when both elements are mutagenized together. Hence, the CRE-like element and the exon-located AP-2-binding site have a cooperative impact on basal transcription, but each element can independently convey the effect of activators of the protein kinase C- and A-dependent pathways of signal transduction. The results of band-shift analysis and competition titration experiments demonstrate that the CRE-like element acts as a low affinity binding site for the same proteins which recognize the authentic CRE.

Amanitins↗
PubMed1989

[The cAMP content and cAMP-dependent protein kinase activity in the brain of rabbits in the dynamics of moderate craniocerebral trauma].

An intracellular concentration of cAMP is a factor to define activity of cAMP-dependent protein kinases. Enzyme activity changes in cytosol and microsomal fractions from investigated brain's regions. Two-phase character of posttraumatic changes of A-kinases activity is shown. Linear dependence for microsomal fractions obtained from brain's hemispheres is observed between A-kinases activity and calculated equilibrium cAMP concentration in different time after experimental cranial trauma.

Animals↗
PubMed1988

[Dynamics of cAMP contents and cAMP-binding capacity of tissue in the healing of different types of wound in animal experiments].

The paper considers the alterations in the cAMP and cAMP-binding capacity of proteins in the tissues of aseptic and infected wounds on 220 experimental Wistar male rats weighing 200-210 g. Variations of cyclic nucleotide levels in the time course of wound healing have been found to be dependent on the ratio between free and bound forms of cyclic nucleotides. There are stated the differences in the cAMP level range that arise from a variety of reasons during the healing of infected and aseptic wounds.

Animals↗
PubMed1995

TGF-beta 1 and cAMP attenuate cyclin A gene transcription via a cAMP responsive element through independent pathways.

Transforming growth factor beta (TGF-beta) is a potent inhibitor of the proliferation of many cell lines. The expression of Cyclin A is down-regulated by TGF-beta 1 in Chinese hamster lung fibroblasts and most of this effect is mediated at the transcriptional level through a cAMP-responsive element (CRE), but does not require a functional cAMP-dependent protein kinase. However, activation of the cAMP pathway in these cells gives rise to a strong inhibition of proliferation, paralleled by a down-regulation of Cyclin A promoter activity. This effect requires the integrity of the CRE, suggesting a role for CRE-binding proteins in late G1/S controls.

Animals↗
PubMed1981

Regulation of the synthesis of adenylate cyclase in Escherichia coli by the cAMP -- cAMP receptor protein complex.

The synthesis of the adenylate cyclase [ATP pyrophosphatelyase-(cyclizing), E.C. 4.6.1.1.] of Escherichia coli, appears to be regulated negatively by the cAMP receptor protein, CRP. This conclusion is based on a comparison of adenylate cyclase activities measured in vitro with the rates of cAMP synthesis by intact bacteria. The activity of adenylate cyclase, depending on conditions of growth, is also regulated by CRP; this effect, however, is indirect insofar as it is mediated by a protein or proteins under CRP control.

Adenylyl Cyclases↗
PubMed1991

Phosphorylation of cAMP response element-binding protein, CRE-BP1, by cAMP-dependent protein kinase and protein kinase C.

The human recombinant CRE-BP1 was phosphorylated by cAMP-dependent protein kinase and protein kinase C, in vitro. These two protein kinases modified distinct serine residues of CRE-BP1. Ser-62 downstream of a putative metal finger structure of CRE-BP1 was the phosphorylation site by cAMP-dependent protein kinase, whereas two serine residues, Ser-340 and Ser-367, located in the basic region of this protein were the major protein kinase C phosphorylation sites. It seems possible that transcriptional and DNA-binding activities of CRE-BP1 are regulated by phosphorylation with these protein kinases.

Amino Acid Sequence↗
PubMed1986

cAMP mediated proteolysis of the catalytic subunit of cAMP-dependent protein kinase.

The cAMP-dependent protein kinase from LLC-PK1 cells can be activated in vivo by calcitonin and vasopressin, or forskolin. Continuous treatment of cells with these agents results in a decrease of total cAMP-PK activity. The loss of kinase activity was enhanced when either of these three agents was incubated in the presence of isobutylmethylxanthine. Results obtained using affinity purified antibodies to the catalytic subunit show that the loss of kinase was due to specific proteolysis of this subunit.

1-Methyl-3-isobutylxanthine↗
PubMed1983

Meiotic resumption and intracellular cAMP levels in mouse oocytes treated with compounds which act on cAMP metabolism.

We have studied the effect of agents known to stimulate adenylate cyclase on spontaneous meiotic resumption in vitro by mouse oocytes. We have found that cholera toxin (CT) (up to 1 microM) and prostaglandin E1 (PGE1) (up to 160 microM) are not able to prevent meiotic resumption, but a clear dose-dependent delay in meiosis resumption was observed during the first 3 h of incubation in medium containing CT or PGE1. The effect became clearer when a small concentration of isobutylmethylxanthine (MIX) (1 microM) was added to the medium. We have also measured the cAMP content of the oocyte: the basal content is 2.1 fmol; this value drops to 0.9 fmol during a 2-h culture period. The decrease is partially prevented if CT is present in the incubation medium, while total cAMP content increases to 3.1 fmol in the presence of 1 mM MIX. The results suggest that isolated mouse oocytes contain toxin and prostaglandin sensitive adenylate cyclase and also an active phosphodiesterase system.

1-Methyl-3-isobutylxanthine↗
PubMed1982

cAMP-dependent and cAMP-independent modulation of synaptic transmission in guinea-pig superior cervical ganglion.

RMI 12330A dose-dependently inhibits cAMP accumulation induced by PGE2 in guinea-pig superior cervical ganglion (SCG). Norepinephrine (NE) is unable to modify cAMP concentration in the same preparation. On the other hand, both PGE2 and NE block the firing discharge of guinea-pig SCG neurons elicited by electrical stimulation (1 Hz) of the cervical sympathetic trunk. The effect of PGE2, but not that of NE, is prevented by RMI 12330A, suggesting that NE and PGE2 act through different pathways

Acetylcholine↗
PubMed1994

Myomodulin application increases cAMP and activates cAMP-dependent protein kinase in the accessory radula closer muscle of Aplysia.

Myomodulin A (MMA) application or stimulation of neuron B16, which releases MMA, increases cAMP levels in the accessory radula closer (ARC) muscle of Aplysia. MMA application also increases cAMP-dependent protein kinase (cAPK) activity in one subcellular compartment of the muscle. These results suggest that at least part of MMA's effects in this system are mediated via the cAPK signal transduction pathway. Since the effects of the small cardioactive peptides (SCPs) on ARC muscle contraction are similar to those of MMA, our results suggest that the convergent physiological effects of MMA and SCPB in this system may be due, in part, to the two peptide neuromodulators utilizing the same signal transduction pathway.

Animals↗
PubMed1995

Determination of phosphodiesterase activity in rat mast cells using the fluorescent cAMP analogue anthraniloyl cAMP.

Cyclic AMP and the isozyme families that control its concentration have an important role in rat mast cells. We have attempted to determine the total phosphodiesterase activity in rat mast cells by means of specific and non-specific inhibitors of phosphodiesterases. We used a fluorescent analogue of cAMP, 2'-O-anthraniloyl cAMP, the fluorescence intensity of which decreases when hydrolysed by phosphadiesterase (PDE), providing a measurement of total activity of PDE. The PDE inhibitors produced a decrease in the fluorescence fall. Therefore, we can establish that at least Type I, III, IV and probably Type V PDE are present in rat mast cells. We have also studied the effect of these PDE inhibitors on histamine release elicited by compound 48/80 and sodium fluoride. Chlorpromazine, a Type I PDE inhibitor, only slightly inhibits the fluoride-evoked response, while, on the other hand, milrinone, a Type III PDE inhibitor, does not modify the response to compound 48/80.

Affinity Labels↗