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1

Cyclic AMP-responsive element-dependent activation of Epstein-Barr virus zebra promoter by human herpesvirus 6.  

PubMed Central

We have recently shown that infection of Epstein-Barr virus (EBV) genome-positive B cells by human herpesvirus 6 (HHV-6) results in the expression of the immediate-early EBV Zebra gene, followed by virus replication (L. Flamand, I. Stefanescu, D. V. Ablashi, and J. Menezes, J. Virol. 67:6768-6777, 1993). Here we show that HHV-6 upregulates Zebra gene transcription through a cyclic AMP-responsive element (CRE) located within the Zebra promoter (Zp). Using human B- or T-cell lines transfected with ZpCat reporter gene constructs, we demonstrate that a region designated the ZII domain of Zp is the target of HHV-6 transactivation. Mutation of the consensus AP-1/CRE site within ZII abolished the inducibility of Zp by HHV-6, whereas positioning of the ZII domain upstream of the beta-globin minimal promoter conferred responsiveness following HHV-6 infection. Binding of these factors to ZII was prevented by oligonucleotides containing CRE but not by AP-1 consensus sequences. Antibodies against CRE-binding (CREB) protein but not against c-Fos or c-Jun were able to supershift the DNA-protein complex, identifying the nature of the transcription factor which binds to ZII as a member of the CREB family of proteins. Finally, transfection of CREB protein and protein kinase A expression vectors were found to activate Zp in Jurkat cells, suggesting that phosphorylated form of CREB protein can play a determining role in the EBV reactivation process.

Flamand, L; Menezes, J

1996-01-01

2

Regulation of Cyclic AMP Response Element Binding and Hippocampal Plasticity-Related Genes by Peroxisome Proliferator-Activated Receptor ?.  

PubMed

Peroxisome proliferator-activated receptor ? (PPAR?) is a transcription factor that regulates genes involved in fatty acid catabolism. Here, we provide evidence that PPAR? is constitutively expressed in nuclei of hippocampal neurons and, surprisingly, controls calcium influx and the expression of various plasticity-related genes via direct transcriptional regulation of cyclic AMP response element binding (CREB). Accordingly, Ppar?-null, but not Ppar?-null, mice are deficient in CREB and memory-associated proteins and have decreased spatial learning and memory. Small hairpin RNA knockdown of PPAR? in the hippocampus suppressed CREB and NR2A, rendering wild-type animals markedly poor in consolidating spatial memory, whereas introduction of PPAR? to the hippocampus of Ppar?-null mice increased hippocampal CREB and NR2A and improved spatial learning and memory. Through detailed analyses of CREB and NR2A activity, as well as spatial learning and memory in bone marrow chimeric animals lacking PPAR? in the CNS, we uncover a mechanism for transcriptional control of Creb and associated plasticity genes by PPAR?. PMID:23972989

Roy, Avik; Jana, Malabendu; Corbett, Grant T; Ramaswamy, Shilpa; Kordower, Jeffrey H; Gonzalez, Frank J; Pahan, Kalipada

2013-08-22

3

A Drosophila CREB/CREM homolog encodes multiple isoforms, including a cyclic AMP-dependent protein kinase-responsive transcriptional activator and antagonist.  

PubMed Central

We have characterized a Drosophila gene that is a highly conserved homolog of the mammalian cyclic AMP (cAMP)-responsive transcription factors CREB and CREM. Uniquely among Drosophila genes characterized to date, it codes for a cAMP-responsive transcriptional activator. An alternatively spliced product of the same gene is a specific antagonist of cAMP-inducible transcription. Analysis of the splicing pattern of the gene suggests that the gene may be the predecessor of the mammalian CREB and CREM genes.

Yin, J C; Wallach, J S; Wilder, E L; Klingensmith, J; Dang, D; Perrimon, N; Zhou, H; Tully, T; Quinn, W G

1995-01-01

4

Response of the human T-cell leukemia virus type 1 long terminal repeat to cyclic AMP.  

PubMed Central

The sequences that control transcriptional initiation of the provirus of the human T-cell leukemia virus type 1 (HTLV-1) are shown to be responsive to intracellular levels of cyclic AMP. A heptanucleotide sequence present within the 21-nucleotide repeat sequence that is similar to the cyclic AMP-responsive consensus (CRE) sequence was required for cyclic AMP-mediated increase in gene expression. Although the CRE-like sequences were contained within sequences that were responsive to the virally encoded trans-activator (tax), the evidence presented indicates that the mechanisms of promoter induction by the tax product and cyclic AMP are independent. The implication of cyclic AMP stimulation of HTLV-1 provirus gene expression for long-term persistence of infected T cells and for virus-induced transformation is discussed. Images

Poteat, H T; Kadison, P; McGuire, K; Park, L; Park, R E; Sodroski, J G; Haseltine, W A

1989-01-01

5

Evidence for a significant role of a G s -triggered mechanism unrelated to the activation of adenylyl cyclase in the cyclic AMP-independent relaxant response of guinea-pig tracheal smooth muscle  

Microsoft Academic Search

Cyclic AMP is a key molecule in the regulation of airway smooth muscle tone. Increased cyclic AMP leads to relaxation of this smooth muscle and its inhibition results in the muscle contraction. A constitutive role for cyclic AMP in the contraction and relaxation of airway muscle is supported by the observations that direct activators of adenylyl cyclase, such as forskolin

Yoshio Tanaka; Yoko Yamashita; Fumiko Yamaki; Takahiro Horinouchi; Koki Shigenobu; Katsuo Koike

2003-01-01

6

Reversal of resistance to adriamycin by 8-chloro-cyclic AMP in adriamycin-resistant HL-60 leukemia cells is associated with reduction of type I cyclic AMP-dependent protein kinase and cyclic AMP response element-binding protein DNA-binding activities.  

PubMed

8-Chloro-cyclic AMP (8-Cl-cAMP) produces growth-inhibitory and differentiating activity in the promyelocytic leukemia cell line HL-60. Adriamycin (ADR)-resistant HL-60 (HL-60/AR) cells exhibit the multidrug-resistant phenotype but do not express the mdr1 gene product P-glycoprotein. To explore potential signaling processes that may be involved in this atypical form of drug resistance, 8-Cl-cAMP was used as a modulator of the cAMP second messenger signal transduction pathway. Treatment for 48 hr with a 10% inhibitory concentration of 8-Cl-cAMP potentiated ADR cytotoxicity 14-fold in HL-60/AR cells but not in the parental cell line. 8-Cl-cAMP was stable to hydrolysis in the medium after 48 hr and was present intracellularly predominantly as phosphorylated metabolites (70%) and the parent compound (30%). No difference occurred in ADR accumulation in HL-60/AR cells after treatment with 8-Cl-cAMP. Accompanying the 8-Cl-cAMP-mediated increase in ADR cytotoxicity in HL-60/AR cells was a reduction in the cytosolic type I cAMP-dependent protein kinase (PKA) and disappearance of the nuclear PKA holoenzyme. Coincident with these changes in drug-resistant cells was a marked reduction in the DNA-binding activity of the cAMP response element-binding protein to levels equivalent to those in sensitive cells. This effect appears to result from reduced phosphorylation of the cAMP response element-binding protein. These results suggest that the potentiation by 8-Cl-cAMP of ADR cytotoxicity in HL-60/AR cells occurs through down-regulation of nuclear type I PKA and cAMP response element-binding factors whose activities are regulated by PKA. PMID:8383802

Rohlff, C; Safa, B; Rahman, A; Cho-Chung, Y S; Klecker, R W; Glazer, R I

1993-03-01

7

A Pivotal Role of Cyclic AMP-Responsive Element Binding Protein in Tumor Progression  

Microsoft Academic Search

Tumor microenvironment controls the selection of malignant cells ca- pable of surviving in stressful and hypoxic conditions. The transcription factor, cyclic AMP-responsive element binding (CREB) protein, activated by multiple extracellular signals, modulates cellular response by regulat- ing the expression of a multitude of genes. Previously, we have demon- strated that two cystein residues, at the DNA binding domain of CREB,

Rinat Abramovitch; Einat Tavor; Jasmine Jacob-Hirsch; Evelyne Zeira; Ninette Amariglio; Orit Pappo; Gideon Rechavi; Eithan Galun; Alik Honigman

2004-01-01

8

Mutants of PC12 cells with altered cyclic AMP responses  

SciTech Connect

PCl2 cells, derived from a rat pheochromocytoma, were mutagenized and selected in media containing agents known to elevate intracellular concentrations of cyclic AMP (cAMP). More than 40 clones were isolated by selection with cholera toxin or 2-chloroadenosine or both. The variants that were deficient in accumulating cAMP were obtained by using a protocol in which 1 ..mu..m 8-bromo-cAMP was included in addition to the agonist. Certain of these variants were partially characterized with respect to the site of altered cAMP metabolism. The profiles of adenylate cyclase activity responsiveness of certain variants to guanosine-5'-(BETA,..gamma..-imido) triphosphate and to forskolin resembled those of UNC and cyc phenotypes of S49 lymphoma cells, which are functionally deficient in the GTP-sensitive coupling protein, N/sub s/. Other variants were characterized by increased cyclic nucleotide phosphodiesterase activity at low substrate concentration. Diverse morphological traits were observed among the variants, but it was not possible to assign them to a particular cAMP phenotype. Two revertants of a PCl2 mutant were isolated and observed to have regained a cellular cAMP response to 2-chloroadenosine and to forskolin. It is hoped that these PCl2 mutants will have utility for defining cAMP-mediated functions, including any links to the action of nerve growth factor, in cells derived from the neural crest.

Block, T.; Kon, C.; Breckenridge, B.M.

1984-10-01

9

Direct activation of cardiac pacemaker channels by intracellular cyclic AMP  

Microsoft Academic Search

CYCLIC AMP acts as a second messenger in the modulation of several ion channels1-9 that are typically controlled by a phosphorylation process10. In cardiac pacemaker cells, adrenaline and acetylcholine regulate the hyperpolarization-activated current (if), but in opposite ways; this current is involved in the generation and modulation of pacemaker activity11. These actions are mediated by cAMP and underlie control of

Dario Difrancesco; Paolo Tortora

1991-01-01

10

Chronic nicotine administration impairs activation of cyclic AMP-response element binding protein and survival of newborn cells in the dentate gyrus.  

PubMed

Chronic intake of nicotine can impair hippocampal plasticity, but the underlying mechanism is poorly understood. Here, we demonstrate that chronic nicotine administration in adult rats inactivates the cyclic AMP-response element binding protein (CREB), a transcription factor that regulates neurogenesis and other plasticity-related processes necessary for learning and memory. Consequently, we showed that impaired CREB signaling is associated with a significant decline in the production of new neurons in the dentate gyrus. Combining retrovirus labeling with gene expression approaches, we found that chronic nicotine administration reduces the number of adult-generated granule neurons by decreasing the survival of newborn cells but not the proliferation of progenitor cells. Additionally, we found that retroviral-mediated expression of a constitutively active CREB in the dentate gyrus rescues survival of newborn cells and reverses the nicotine-induced decline in the number of mature granule neurons. Prolonged nicotine exposure also compromises CREB activation and reduces the viability of progenitor cells in vitro, thereby suggesting that nicotine may exert its adverse effects directly on immature cells in vivo. Taken together, these data demonstrate that inhibition of CREB activation is responsible for the nicotine-induced impairment of hippocampal plasticity. PMID:21740234

Wei, Zelan; Belal, Cherine; Tu, Weihong; Chigurupati, Srinivasulu; Ameli, Neema Jason; Lu, Youming; Chan, Sic L

2011-08-29

11

Induction of cyclooxygenase-2 by ginsenoside Rd via activation of CCAAT-enhancer binding proteins and cyclic AMP response binding protein  

SciTech Connect

Panax ginseng is a widely used herbal medicine in East Asia and is reported to have a variety of pharmacological effects against cardiovascular diseases and cancers. Here we show a unique effect of ginsenoside Rd (Rd) on cyclooxygenase-2 (COX-2) expression in RAW264.7 macrophages. Rd (100 {mu}g/ml), but not other ginsenosides induced COX-2 and increased prostaglandin E{sub 2} production. Gel shift and Western blot analyses using nuclear fractions revealed that Rd increased both the DNA binding of and the nuclear levels of CCAAT/enhancer binding protein (C/EBP){alpha}/{beta} and cyclic AMP response element binding protein (CREB), but not of p65, in RAW264.7 cells. Moreover, Rd increased the luciferase reporter gene activity in cells transfected with a 574-bp mouse COX-2 promoter construct. Site-specific mutation analyses confirmed that Rd-mediated transcriptional activation of COX-2 gene was regulated by C/EBP and CREB. These results provide evidence that Rd activated C/EBP and CREB, and that the activation of C/EBP and CREB appears to be essential for induction of COX-2 in RAW264.7 cells.

Jeong, Hye Gwang [BK21 Project Team, College of Pharmacy, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759, South Korea (Korea, Republic of); Pokharel, Yuba Raj [BK21 Project Team, College of Pharmacy, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759, South Korea (Korea, Republic of); Han, Eun Hee [BK21 Project Team, College of Pharmacy, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759, South Korea (Korea, Republic of); Kang, Keon Wook [BK21 Project Team, College of Pharmacy, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759, South Korea (Korea, Republic of)]. E-mail: kwkang@chosun.ac.kr

2007-07-20

12

Cyclic AMP-independent ATF family members interact with NF-kappa B and function in the activation of the E-selectin promoter in response to cytokines.  

PubMed Central

We previously reported that NF-kappa B and a complex we referred to as NF-ELAM1 play a central role in cytokine-induced expression of the E-selectin gene. In this study we identify cyclic AMP (cAMP)-independent members of the ATF family binding specifically to the NF-ELAM1 promoter element. The NF-ELAM1 element (TGACATCA) differs by a single nucleotide substitution from the cAMP-responsive element consensus sequence. We demonstrate that this sequence operates in a cAMP-independent manner to induce transcription and thus define it as a non-cAMP-responsive element (NCRE). We show that ATFa is a component of the NF-ELAM1 complex and its overexpression activates the E-selectin promoter. In addition, ATFa, ATF2, and ATF3 interact directly with NF-kappa B in vitro, linking two unrelated families of transcription factors in a novel protein-protein interaction. Furthermore, we demonstrate that the ability of overexpressed NF-kappa B to transactivate the E-selectin promoter in vivo is dependent on the NF-ELAM1 complex. Our results suggest that a direct interaction between ATFs and NF-kappa B is, at least in part, the mechanism by which these factors specifically regulate E-selectin promoter activity. Images

Kaszubska, W; Hooft van Huijsduijnen, R; Ghersa, P; DeRaemy-Schenk, A M; Chen, B P; Hai, T; DeLamarter, J F; Whelan, J

1993-01-01

13

Inhibition of membrane depolarisation-induced transcriptional activity of cyclic AMP response element binding protein (CREB) by the dual-leucine-zipper-bearing kinase in a pancreatic islet beta cell line  

Microsoft Academic Search

Aims\\/hypothesis  The activation of the transcription factor cyclic AMP response element binding protein (CREB) by protein kinase A is inhibited\\u000a by the human orthologue of the mitogen-activated protein kinase, dual-leucine-zipper-bearing kinase (DLK) in teratocarcinoma\\u000a cells. However, pancreatic beta cells are electrically excitable and a major pathway regulating CREB in these cells is membrane\\u000a depolarisation, leading to calcium influx and activation of

E. Oetjen; A. Lechleiter; R. Blume; D. Nihalani; L. Holzman; W. Knepel

2006-01-01

14

Ca(2+)-cyclic AMP interactions in sustained cellular responses.  

PubMed

As early as 1970 it was apparent that the cyclic AMP (cAMP) and Ca2+ messenger systems often interact to regulate cellular responses. Work over the past 20 years has greatly expanded our knowledge of these interactions, and has shown that these signalling systems interact in complex ways to regulate sustained cellular responses such as aldosterone secretion, smooth muscle contraction and insulin secretion. The latter system is considered in detail because it illustrates several types of interactions, both positive and negative, which help to determine the normal response of beta-cells to physiological stimuli, and how abnormalities in secretory patterns can develop as a consequence of the prolonged stimulation of a messenger system. PMID:1356716

Rasmussen, H; Isales, C; Ganesan, S; Calle, R; Zawalich, W

1992-01-01

15

Activation of Mitogen-Activated Protein Kinases and Cyclic Amp Response Element-Binding Protein in Synaptic Plasticity.  

National Technical Information Service (NTIS)

Current evidence supports a critical role for cAMP in synaptic plasticity. Forskolin increases adenylyl cyclase activity to generate cAMP which induces a long-lasting potentiation of excitatory postsynaptic potentials in the hippocaznpal dentate gyrus to ...

P. J. Voulalas

1997-01-01

16

Relationship between the activation of cyclic AMP responsive element binding protein and ischemic tolerance in the penumbra region of rat cerebral cortex.  

PubMed

Application of a brief period of ischemia, i.e. preconditioning treatment of the middle cerebral artery territory, has been known to produce ischemic tolerance, reducing cerebral infarction volume in the penumbra region after lethal ischemia. However, little is known about the molecular mechanisms responsible for preconditioning-induced ischemic tolerance. In the present study, we examined the difference in the phosphorylation pattern of cyclic AMP responsive element binding protein (CREB) after 1 h of focal cerebral ischemia between preconditioned and non-preconditioned rats by immunohistochemistry and Western blotting. The phosphorylation of CREB in the penumbra region was more rapidly enhanced in the preconditioned rats than in the non-preconditioned rats after 1 h of ischemia. The result suggested that the immediate enhancement in the phosphorylation of CREB in the penumbra region prevented the spread of infarction in the preconditioned rats. PMID:12359312

Nakajima, Takayuki; Iwabuchi, Sadahiro; Miyazaki, Hiroyuki; Okuma, Yasunobu; Inanami, Osamu; Kuwabara, Mikinori; Nomura, Yasuyuki; Kawahara, Koichi

2002-10-01

17

Activation of protein kinase C via the T-cell receptor complex potentiates cyclic AMP responses in T-cells.  

PubMed

We have recently shown that activation of protein kinase C by tumour promoting phorbolesters, such as 4 beta-phorbol-12,13-dibutyrate, stimulates adenosine-induced accumulation of cAMP in Jurkat cells, a human T-leukaemia line. Activating the CD3 complex associated with the T-cell receptor by means of the monoclonal antibody OKT3 caused a concentration-dependent accumulation of inositol phosphates and an increase in the phosphorylation of an endogenous protein kinase C substrate. OKT3 also mimicked the previously reported effects of protein kinase C since it potentiated the cAMP stimulation by either an adenosine analogue, NECA, or cholera toxin. Thus, our results indicate that stimulation of a receptor activating phospholipase C and protein kinase C can secondarily enhance the action of agonists that act on adenylate cyclase-coupled receptors. PMID:2561306

Kvanta, A; Nordstedt, C; Jondal, M; Fredholm, B B

1989-12-01

18

Cyclic AMP-dependent protein kinase in mammary tissue of the lactating rat. Activity ratio and responsiveness of the target enzymes acetyl-CoA carboxylase and glycogen phosphorylase to beta-adrenergic stimulation.  

PubMed Central

The role of cyclic AMP in acute regulation of the metabolism of mammary tissue in the lactating rat was examined by measuring the activity ratio of cyclic AMP-dependent protein kinase (A-kinase) and by examining the properties of this enzyme in its two major isoenzymic forms. Isoenzyme II is the major form in soluble extracts of rat mammary tissue. A-kinase activity ratio in such extracts is unaffected by starvation of the lactating rat. Treatment of the intact rat with isoprenaline, or addition of isoprenaline to incubations in vitro of mammary acini, resulted in a major increase in the activity ratio of A-kinase. These treatments equally affected isoenzymes I and II. The treatment in vitro lead to a rapid depletion of A-kinase as subsequently measured in extracts of acini. The degree of activation of the enzymes acetyl-CoA carboxylase and glycogen phosphorylase in extracts of mammary tissue and of acini was assessed as a function of these treatments. The increased activation of A-kinase induced by isoprenaline was unaccompanied by significant changes in the activity of acetyl-CoA carboxylase in acini, although we previously showed that this agent activates acetyl-CoA carboxylase in intact mammary tissue. Contrastingly, isoprenaline-induced enhancement of A-kinase activity was accompanied by an increase in the activity ratio of phosphorylase in acini. These results indicate that: (a) a normal response of expressed A-kinase activity to cyclic AMP operates in mammary acini and mammary tissue from lactating rats; (b) rapid modulation of the total amount of soluble A-kinase is mediated in mammary epithelial cells by cyclic AMP; (c) phosphorylase, an ultimate target of the protein phosphorylation cascade initiated by A-kinase, is activated in acini under conditions where A-kinase activity is enhanced; and (d) mechanisms other than that of the A-kinase phosphorylation/inhibition model for acetyl-CoA carboxylase regulation must operate in mammary tissue preparations and in vivo to account for the response of this enzyme to enhanced A-kinase activity.

Clegg, R A; Ottey, K A

1990-01-01

19

The role of calcium in the cyclic AMP response to histamine in rabbit cerebral cortical slices.  

PubMed Central

The effect of calcium on the H1- and H2-receptor components of the cyclic AMP response to histamine in rabbit cerebral cortical slices has been investigated. Removal of calcium ions from the incubation medium during the preparation, preincubation and final incubation of brain slices significantly reduced the cyclic AMP responses to adenosine, histamine and the H2-selective agonist, impromidine. Removal of calcium ions from the incubation medium during only the final incubation with agonists did not influence the responses to adenosine, histamine, impromidine and the H1-selective agonist, 2-thiazolylethylamine. Final incubation of rabbit cerebral cortical slices in calcium-free buffer containing EGTA (1 mM) however, selectively reduced the cyclic AMP responses to the H1-agonists histamine and 2-thiazolylethylamine without affecting the response to impromidine or adenosine. These latter incubation conditions significantly reduced the maximal extent of the augmentation of impromidine- or adenosine-stimulated cyclic AMP accumulation produced by H1-receptor stimulation, without affecting the EC50 values of the H1-agonists. Calcium-free/EGTA conditions did not, however, alter the dose-response parameters for the response to the H2-agonist, impromidine. These data provide further evidence that the two histamine receptor systems affect cyclic AMP accumulation in rabbit cerebral cortical slices by different mechanisms.

Al-Gadi, M.; Hill, S. J.

1987-01-01

20

Low-Power Laser Irradiation Suppresses Inflammatory Response of Human Adipose-Derived Stem Cells by Modulating Intracellular Cyclic AMP Level and NF-?B Activity  

PubMed Central

Mesenchymal stem cell (MSC)-based tissue regeneration is a promising therapeutic strategy for treating damaged tissues. However, the inflammatory microenvironment that exists at a local injury site might restrict reconstruction. Low-power laser irradiation (LPLI) has been widely applied to retard the inflammatory reaction. The purpose of this study was to investigate the anti-inflammatory effect of LPLI on human adipose-derived stem cells (hADSCs) in an inflammatory environment. We showed that the hADSCs expressed Toll-like Receptors (TLR) 1, TLR2, TLR3, TLR4, and TLR6 and that lipopolysaccharide (LPS) significantly induced the production of pro-inflammatory cytokines (Cyclooxygenase-2 (Cox-2), Interleukin-1? (IL-1?), Interleukin-6 (IL-6), and Interleukin-8 (IL-8)). LPLI markedly inhibited LPS-induced, pro-inflammatory cytokine expression at an optimal dose of 8 J/cm2. The inhibitory effect triggered by LPLI might occur through an increase in the intracellular level of cyclic AMP (cAMP), which acts to down-regulate nuclear factor kappa B (NF-?B) transcriptional activity. These data collectively provide insight for further investigations of the potential application of anti-inflammatory treatment followed by stem cell therapy.

Wang, Chau-Zen; Ho, Mei-Ling; Yeh, Ming-Long; Wang, Yan-Hsiung

2013-01-01

21

Activation of pp70/85 S6 kinases in interleukin-2-responsive lymphoid cells is mediated by phosphatidylinositol 3-kinase and inhibited by cyclic AMP.  

PubMed Central

Activation of phosphatidylinositol 3-kinase (PI3K) and activation of the 70/85-kDa S6 protein kinases (alpha II and alpha I isoforms, referred to collectively as pp70S6k) have been independently linked to the regulation of cell proliferation. We demonstrate that these kinases lie on the same signalling pathway and that PI3K mediates the activation of pp70 by the cytokine interleukin-2 (IL-2). We also show that the activation of pp70S6k can be blocked at different points along the signalling pathway by using specific inhibitors of T-cell proliferation. Inhibition of PI3K activity with structurally unrelated but highly specific PI3K inhibitors (wortmannin or LY294002) results in inhibition of IL-2-dependent but not phorbol ester (conventional protein kinase C [cPKC])-dependent pp70S6k activation. The T-cell immunosuppressant rapamycin potently antagonizes IL-2-(PI3K)- and phorbol ester (cPKC)-mediated activation of pp70S6k. Thus, wortmannin and rapamycin antagonize IL-2-mediated activation of pp70S6k at distinct points along the PI3K-regulated signalling pathway, or rapamycin antagonizes another pathway required for pp70S6k activity. Agents that raise the concentration of intracellular cyclic AMP (cAMP) and activate cAMP-dependent protein kinase (PKA) also inhibit IL-2-dependent activation of pp70S6k. In this case, inhibition appears to occur at least two points in this signalling path. Like rapamycin, PKA appears to act downstream of cPKC-mediated pp70S6k activation, and like wortmannin, PKA antagonizes IL-2-dependent activation of PI3K. The results with rapamycin and wortmannin are of added interest since the yeast and mammalian rapamycin targets resemble PI3K in the catalytic domain.

Monfar, M; Lemon, K P; Grammer, T C; Cheatham, L; Chung, J; Vlahos, C J; Blenis, J

1995-01-01

22

CyclicAMP Response Element-Based Signaling Assays for Characterization of Trk Family Tyrosine Kinases Modulators  

Microsoft Academic Search

Neurotrophins (NTs) induce gene transcription by binding their high-affinity tropomyosin-related kinase (Trk) receptors and initiating intracellular signal transduction cascades. In particular, activation of the cyclic AMP response element (CRE) in the promoters of target genes serves as surrogate markers for Trk receptor activation as demonstrated in both in vivo and in vitro systems. We used a HEK293 cell line stably

Jie Zhang; Diana Chen; Xiaohai Gong; Huaiping Ling; Guoming Zhang; Andrew Wood; Julia Heinrich; Seongeun Cho

2006-01-01

23

A simple electrostatic switch important in the activation of type I protein kinase A by cyclic AMP  

Microsoft Academic Search

Cyclic AMP activates protein kinase A by binding to an inhibitory regulatory (R) subunit and releasing inhibition of the catalytic (C) subunit. Even though crystal structures of regulatory and catalytic subunits have been solved, the precise molecular mechanism by which cyclic AMP activates the kinase remains unknown. The dynamic properties of the cAMP binding domain in the absence of cAMP

DOMINICO VIGIL; JUNG-HSIN LIN; CHRISTOPH A. SOTRIFFER; JUNIPER K. PENNYPACKER; J. ANDREW MCCAMMON; SUSAN S. TAYLOR

2006-01-01

24

Structural overview on the allosteric activation of cyclic AMP receptor protein  

Microsoft Academic Search

Cyclic AMP receptor protein (CRP) is a prokaryotic global transcription regulator that controls the expression of nearly 200 genes. The protein, allosterically activated by cAMP binding, binds to DNA and interacts with RNA polymerase. Current understanding on the allosteric process of the Escherichia coli CRP activation can be summarized into a rigid-body movement that involves subunit realignment and domain rearrangement.

Hyung-Sik Won; Yoo-Sup Lee; Sung-Hee Lee; Bong-Jin Lee

2009-01-01

25

Negative cyclic AMP response elements in the promoter of the L-type pyruvate kinase gene  

Microsoft Academic Search

L-type pyruvate kinase gene expression is modulated by hormonal and nutritional conditions. Here, we show by transient transfections in hepatocytes in primary culture that both the glucose response element and the contiguous hepatocyte nuclear factor 4 (HNF4) binding site (L3) of the promoter were negative cyclic AMP (cAMP) response elements and that cAMP-dependent inhibition through L3 requires HNF4 binding. Another

Laurence Gourdon; Dan Qing Lou; Michel Raymondjean; Mireille Vasseur-Cognet; Axel Kahn

1999-01-01

26

A unique enhancer element for the trans activator (p40 sup tax ) of human T-cell leukemia virus type I that is distinct from cyclic AMP- and 12-O-tetradecanoylphobol-13-acetate-responsive elements  

SciTech Connect

The trans activator (p40{sup tax}) of human T-cell leukemia virus type I (HTLV-I) is a transcriptional factor that activates the long terminal repeat (LTR) of HTLV-I and interleukin-2 receptor {alpha}. The authors examined the HTLV-I enhancer responsible for tax-mediated trans activation and identified (A/T)(G/C)(G/C)CNNTGACG(T/A) as a plausible tax-responsive element (TRE). The putative TRE in the LTR was found to be different from the elements required for activation by cyclic AMP and 12-O-tetradecanoylphorbol-13-acetate, although these elements overlapped each other. The TRE was also different from a binding site of N-{kappa}B-like factor that was identified was identified in the interleukin-2 receptor {alpha} promoter and human immunodeficiency virus LTR as a TRE. The latter result was further demonstrated by the failure of the NF-{kappa}B sequence to compete with the TRE of the LTR in a protein-binding assay. These findings indicate that tax function and its cascade can modulate activities of various enhancer sequences, which are probably regulated by distinct DNA-binding factors.

Fujisawa, Junichi; Toita, Masami; Yoshida, Mitsuaki (Cancer Institute, Tokyo (Japan))

1989-08-01

27

Noradrenaline-sensitive cyclic AMP-generating system of rat cerebral cortex with iron-induced epileptiform activity.  

PubMed

Noradrenaline-elicited accumulation of cyclic AMP and effects of an alpha-, beta-adrenoceptor, or adenosine receptor antagonist on the accumulation were examined in slices of different areas of rat cerebral cortex in which ferrous chloride solution was injected unilaterally into the sensorimotor cortex to induce epileptiform activity. The cyclic AMP accumulation was altered regionally in relation to both lateral dominance of electrographic isolated spike activity and variance of the epileptic process. Involvement of a beta-adrenergic, and possibly alpha-adrenergic, mechanism in the alterations in the cyclic AMP accumulation was indicated. PMID:2886687

Hattori, Y; Moriwaki, A; Yasuhara, H; Hori, Y

1987-01-01

28

Activity-Dependent Regulation of HCN Pacemaker Channels by Cyclic AMP  

Microsoft Academic Search

Signal transduction in neurons is a dynamic process, generally thought to be driven by transient changes in the concentration of second messengers. Here we describe a novel regulatory mechanism in which the dynamics of signaling through cyclic AMP are mediated by activity-dependent changes in the affinity of the hyperpolarization-activated, cation nonselective (HCN) channels for cAMP, rather than by changes in

Jing Wang; Shan Chen; Matthew F Nolan; Steven A Siegelbaum

2002-01-01

29

Dose-related antiallodynic effects of cyclic AMP response element-binding protein-antisense oligonucleotide in the spared nerve injury model of neuropathic pain  

Microsoft Academic Search

A transcription factor known as cyclic AMP response element-binding protein has been shown to be involved in the central sensitization in neuropathic pain and inflammation pain. The present study examined the roles of cyclic AMP response element-binding protein and of the phosphorylated cyclic AMP response element-binding protein in the maintenance of mechanical and cold allodynia induced by a neuropathic pain

Y.-Y. Wang; S.-X. Wu; L. Zhou; J. Huang; W. Wang; X.-Y. Liu; Y.-Q. Li

2006-01-01

30

Spatial Memory in the Morris Water Maze and Activation of Cyclic AMP Response Element-Binding (CREB) Protein within the Mouse Hippocampus  

ERIC Educational Resources Information Center

|We investigated the spatio-temporal dynamics of learning-induced cAMP response element-binding protein activation/phosphorylation (pCREB) in mice trained in a spatial reference memory task in the water maze. Using immunohistochemistry, we examined pCREB immunoreactivity (pCREB-ir) in hippocampal CA1 and CA3 and related brain structures. During…

Porte, Yves; Buhot, Marie Christine; Mons, Nicole E.

2008-01-01

31

Both the basic region and the 'leucine zipper' domain of the cyclic AMP response element binding (CREB) protein are essential for transcriptional activation.  

PubMed Central

Second messengers like cAMP can activate the transcription of genes containing consesus cAMP response element (CRE). A 43 kd nuclear phosphoprotein previously identified as the cAMP response element binding (CREB) protein has been shown to bind as a dimer to CRE and activate gene transcription. The rat and human CREB protein contain the 'leucine zipper' motif. We have analyzed the role of both leucine zipper domain and the amino-terminal basic region by making site-specific mutations. Our results show that the first three leucines int he leucine zipper domain are essential for efficient dimer formation. Mutations of two consecutive leucines in the leucine zipper domain completely abolish the ability to form dimers. Mutant CREB protein unable to form homodimers is also unable to bind to DNA. In contrast, however, mutations, in the DNA binding region had no effect on dimer formation but were unable to bind to CRE sites or activate transcription. We propose that CREB protein functions by forming homodimers which bind to CRE and activate transcription. Furthermore, the CREB protein needs to be phosphorylated before activating transcription. Finally, we show that the CREB basic region mutant acts as a trans-dominant transcriptional suppressor of wild-type CREB function. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6.

Dwarki, V J; Montminy, M; Verma, I M

1990-01-01

32

Cyclic AMP-receptor protein activates aerobactin receptor IutA expression in Vibrio vulnificus.  

PubMed

The ferrophilic bacterium Vibrio vulnificus can utilize the siderophore aerobactin of Escherichia coli for iron acquisition via its specific receptor IutA. This siderophore piracy by V. vulnificus may contribute to its survival and proliferation, especially in mixed bacterial environments. In this study, we examined the effects of glucose, cyclic AMP (cAMP), and cAMP-receptor protein (Crp) on iutA expression in V. vulnificus. Glucose dose-dependently repressed iutA expression. A mutation in cya encoding adenylate cyclase required for cAMP synthesis severely repressed iutA expression, and this change was recovered by in trans complementing cya or the addition of exogenous cAMP. Furthermore, a mutation in crp encoding Crp severely repressed iutA expression, and this change was recovered by complementing crp. Accordingly, glucose deprivation under iron-limited conditions is an environmental signal for iutA expression, and Crp functions as an activator that regulates iutA expression in response to glucose availability. PMID:22538662

Kim, Choon-Mee; Kim, Seong-Jung; Shin, Sung-Heui

2012-04-27

33

Cyclic AMP Receptor Protein: Role in Transcription Activation  

Microsoft Academic Search

The structure of this pleiotropic activator of gene transcription in bacteria and its interaction sites at promoter DNA's as well as the role of this protein in the RNA polymerase-promoter interactions are reviewed.

Benoit de Crombrugghe; Stephen Busby; Henri Buc

1984-01-01

34

Spatial memory in the Morris water maze and activation of cyclic AMP response element-binding (CREB) protein within the mouse hippocampus.  

PubMed

We investigated the spatio-temporal dynamics of learning-induced cAMP response element-binding protein activation/phosphorylation (pCREB) in mice trained in a spatial reference memory task in the water maze. Using immunohistochemistry, we examined pCREB immunoreactivity (pCREB-ir) in hippocampal CA1 and CA3 and related brain structures. During the course of spatial learning over Days 1-9, pCREB-ir progressively increased in hippocampal neurons whereas its level in the dorsal striatum decreased. No significant changes were observed in the prelimbic cortex and lateral amygdala. Mice killed at various time points after the last training session demonstrated two waves of pCREB-ir in CA1 and an early transient CREB phosphorylation in area CA3, lateral amygdala, and prelimbic cortex. We show that CREB phosphorylation and downstream gene Zif268 activation remained sustained in CA1 and CA3 for at least 24 h after extended training (Days 8-9) but not during early training (Day 3). The present results indicate that the strong CA1 CREB phosphorylation observed immediately after training was not related strictly to learning or to memory. In contrast, at 15 min after training, the changes in CA1 CREB phosphorylation state were specifically related to individual learning capability. We suggest that hippocampal-learning specificity of CREB is reflected best by duration, rather than magnitude, of CREB phosphorylation. PMID:19050160

Porte, Yves; Buhot, Marie Christine; Mons, Nicole E

2008-12-02

35

Bacterial cyclic AMP-phosphodiesterase activity coordinates biofilm formation.  

PubMed

Biofilm-related infections are a major contributor to human disease, and the capacity for surface attachment and biofilm formation are key attributes for the pathogenesis of microbes. Serratia marcescens type I fimbriae-dependent biofilms are coordinated by the adenylate cyclase, CyaA, and the cyclic 3',5'-adenosine monophosphate (cAMP)-cAMP receptor protein (CRP) complex. This study uses S. marcescens as a model system to test the role of cAMP-phosphodiesterase activity in controlling biofilm formation. Herein we describe the characterization of a putative S. marcescens cAMP-phosphodiesterase gene (SMA3506), designated as cpdS, and demonstrated to be a functional cAMP-phosphodiesterase both in vitro and in vivo. Deletion of cpdS resulted in defective biofilm formation and reduced type I fimbriae production, whereas multicopy expression of cpdS conferred a type I fimbriae-dependent hyper-biofilm. Together, these results support a model in which bacterial cAMP-phosphodiesterase activity modulates biofilm formation. PMID:23923059

Kalivoda, Eric J; Brothers, Kimberly M; Stella, Nicholas A; Schmitt, Matthew J; Shanks, Robert M Q

2013-07-29

36

The serum response factor nuclear localization signal: general implications for cyclic AMP-dependent protein kinase activity in control of nuclear translocation.  

PubMed Central

We have identified a basic sequence in the N-terminal region of the 67-kDa serum response factor (p67SRF or SRF) responsible for its nuclear localization. A peptide containing this nuclear localization signal (NLS) translocates rabbit immunoglobulin G (IgG) into the nucleus as efficiently as a peptide encoding the simian virus 40 NLS. This effect is abolished by substituting any two of the four basic residues in this NLS. Overexpression of a modified form of SRF in which these basic residues have been mutated confirms the absolute requirement for this sequence, and not the other basic amino acid sequences adjacent to it, in the nuclear localization of SRF. Since this NLS is in close proximity to potential phosphorylation sites for the cAMP-dependent protein kinase (A-kinase), we further investigated if A-kinase plays a role in the nuclear location of SRF. The nuclear transport of SRF proteins requires basal A-kinase activity, since inhibition of A-kinase by using either the specific inhibitory peptide PKIm or type II regulatory subunits (RII) completely prevents the nuclear localization of plasmid-expressed tagged SRF or an SRF-NLS-IgG conjugate. Direct phosphorylation of SRF by A-kinase can be discounted in this effect, since mutation of the putative phosphorylation sites in either the NLS peptide or the encoded full-length SRF protein had no effect on nuclear transport of the mutants. Finally, in support of an implication of A-kinase-dependent phosphorylation in a more general mechanism affecting nuclear import, we show that the nuclear transport of a simian virus 40-NLS-conjugated IgG or purified cyclin A protein is also blocked by inhibition of A-kinase, even though neither contains any potential sites for phosphorylation by A-kinase or can be phosphorylated by A-kinase in vitro.

Gauthier-Rouviere, C; Vandromme, M; Lautredou, N; Cai, Q Q; Girard, F; Fernandez, A; Lamb, N

1995-01-01

37

Cross-talk between glucagon- and adenosine-mediated signalling systems in rat hepatocytes: effects on cyclic AMP-phosphodiesterase activity.  

PubMed Central

The effect of adenosine analogues on glucagon-stimulated cyclic AMP accumulation in rat hepatocytes was explored. N6-Cyclopentyladenosine (CPA), 5'-N-ethylcarboxamidoadenosine and N6-(R-phenylisopropyl)adenosine inhibited in a dose-dependent manner the cyclic AMP accumulation induced by glucagon. This effect seems to be mediated through A1 adenosine receptors. Pertussis toxin completely abolished the effect of CPA on glucagon-stimulated cyclic AMP accumulation in whole cells which suggested that a pertussis-toxin-sensitive G-protein was involved. On the other hand, this action of adenosine analogues on glucagon-induced cyclic AMP accumulation was reverted by the selective low-Km cyclic AMP-phosphodiesterase inhibitor Ro 20-1724. Analysis of cyclic AMP-phosphodiesterase activity in purified hepatocyte plasma membranes showed that glucagon in the presence of GTP inhibited basal PDE activity by 45% and that CPA reverted this inhibition in dose-dependent manner. In membranes derived from pertussis-toxin-treated rats, we observed no inhibition of cyclic AMP-phosphodiesterase activity by glucagon in the absence or presence of CPA. Our results indicate that in hepatocyte plasma membranes, stimulation of adenylate cyclase activity and inhibition of a low-Km cyclic AMP phosphodiesterase activity are co-ordinately regulated by glucagon, and that A1 adenosine receptors can inhibit glucagon-stimulated cyclic AMP accumulation by blocking glucagon's effect on phosphodiesterase activity. Images Figure 2

Robles-Flores, M; Allende, G; Pina, E; Garcia-Sainz, J A

1995-01-01

38

Transient changes in cyclic AMP and in the enzymic activity of protein kinase and phosphorylase during the cardiac cycle in the canine myocardium and the effect of propranolol  

Microsoft Academic Search

Oscillation of cyclic AMP and in the activity ratio of cyclic AMP-dependent protein kinase and of glycogen phosphorylase with the cardiac cycle were demonstrated in the canine heart in situ. For tissue sampling an ECG (R-wave)-triggered, automatically working push-freeze-drill apparatus was developed which allows intraventricular cryobiopsies from the left ventricular muscle of anaesthetized open-chest dogs. The nucleotide cyclic AMP oscillated

Ernst-Georg Krause; Sabine Bartel; Inge Beyerdörfer; Wolfgang Freier; Karl Gerber; Dankwart Obst

1989-01-01

39

Multistep regulatory system for activation of a cyclic AMP-independent eukaryotic initiation factor 2 kinase.  

PubMed Central

Three functionally related components that block peptide initiation have been identified in lysates of rabbit reticulocytes. The components function consecutively in a cascade type sequence of reactions to cause phosphorylation of eukaryotic peptide initiation factor 2 (eIF-2). The eIF-2 kinase activated as part of this sequence has been tentatively identified as the same protein kinase that is activated by heme deficiency as part of the hemin-controlled repressor (HCR) system. The first component in the sequence is heat stable and can be reversibly activated by heat or pressure. It activates a second, heat-labile, component that in turn directly or indirectly activates the hemin-controlled eIF-2 kinase. This heat-labile component appears to function through proteolysis. This reaction sequence is not detectably affected by heme or cyclic AMP and thus appears to provide an alternative mechanism, independent of heme, for activation of the cyclic AMP-independent eIF-2 kinase of the HCR system. Images

Henderson, A B; Miller, A H; Hardesty, B

1979-01-01

40

TGF-beta 1 induces phosphorylation of the cyclic AMP responsive element binding protein in ML-CCl64 cells.  

PubMed Central

Type beta transforming growth factors represent a family of polypeptides that modulate growth and differentiation. TGF-beta exerts its effects on target cells through interaction with specific cell surface receptors, but the signal transduction pathways are largely unresolved as yet. In this study we report that TGF-beta 1 induces a rapid phosphorylation of the cyclic AMP responsive element binding protein (CREB) in mink lung CCl64 cells. Phosphorylation induced by TGF-beta 1 is not mediated by the cAMP-dependent protein kinase. Parallel to the increase in phosphorylation of CREB, an increase in binding to the collagenase TPA responsive element was observed. CREB participates in the binding to this element, probably as a heterodimer with another as yet unknown protein. The modification imposed on CREB and its involvement in an enhanced TRE-binding could be a mechanism by which TGF-beta 1 induces the TRE-mediated transcriptional activation. Images

Kramer, I M; Koornneef, I; de Laat, S W; van den Eijnden-van Raaij, A J

1991-01-01

41

Cyclic AMP-elevating agents prevent oligodendroglial excitotoxicity.  

PubMed

Previously, we have demonstrated that cells of the oligodendroglial lineage express non-NMDA glutamate receptor genes and are damaged by kainate-induced Ca2+ influx via non-NMDA glutamate receptor channels, representing oligodendroglial excitotoxicity. We find in the present study that agents that elevate intracellular cyclic AMP prevent oligodendroglial excitotoxicity. After oligodendrocyte-like cells, differentiated from the CG-4 cell line established from rat oligodendrocyte type-2 astrocyte progenitor cells, were exposed to 2 mM kainate for 24 h, cell death was evaluated by measuring activity of lactate dehydrogenase released into the culture medium. Released lactate dehydrogenase increased about threefold when exposed to 2 mM kainate. Kainate-induced cell death was prevented by one of the following agents: adenylate cyclase activator (forskolin), cyclic AMP analogues (dibutyryl cyclic AMP and 8-bromo-cyclic AMP), and cyclic AMP phosphodiesterase inhibitors (3-isobutyl-1-methylxanthine, pentoxifylline, propentofylline, and ibudilast). Simultaneous addition of both forskolin and phosphodiesterase inhibitors prevented the kainate-induced cell death in an additive manner. A remarkable increase in Ca2+ influx (approximately 5.5-fold) also was induced by kainate. The cyclic AMP-elevating agents caused a partial suppression of the kainate-induced increase in Ca2+ influx, leading to a less prominent response of intracellular Ca2+ concentration to kainate. The suppressing effect of forskolin on the kainate-induced Ca2+ influx was partially reversed by H-89, an inhibitor of cyclic AMP-dependent protein kinase. In contrast to this, okadaic acid, an inhibitor of protein phosphatases 1 and 2A, brought about a decrease in the kainate-induced Ca2+ influx. We therefore concluded that cyclic AMP-elevating agents prevented oligodendroglial excitotoxicity by cyclic AMP-dependent protein kinase-dependent protein phosphorylation, resulting in decreased kainate-induced Ca2+ influx. PMID:9603206

Yoshioka, A; Shimizu, Y; Hirose, G; Kitasato, H; Pleasure, D

1998-06-01

42

Cyclic AMP inhibits JNK activation by CREB-mediated induction of c-FLIPL and MKP-1, thereby antagonizing UV-induced apoptosis  

Microsoft Academic Search

The cyclic AMP (cAMP) signaling pathway has been reported to either promote or suppress apoptosis, in a cell context-dependent manner. Our previous study has shown that cAMP, by protein kinase A (PKA)–cAMP response element-binding protein (CREB)–dynein light chain (DLC) pathway, negatively regulates mitogen-activated protein kinase p38 activation, thereby contributing to tumor necrosis factor (TNF)-?-induced apoptosis in certain types of cells.

J Zhang; Q Wang; N Zhu; M Yu; B Shen; J Xiang; A Lin

2008-01-01

43

Inhibition by somatostatin of mouse thyroid activity following stimulation by thyrotrophin, isoprenaline and dibutyryl cyclic-AMP.  

PubMed

The recent discovery of somatostatin-containing cells within the thyroid gland infers that somatostatin may influence thyroid activity. This possibility was investigated by measurements of radio-iodine release in mice pre-treated with 125I and T4. The animals were treated with TSH, isoprenaline or dibutyryl-cyclic AMP with and without concomitant injection of somatostatin. It was found that somatostatin reduced the blood 125I increase in response to each of the three thyroid-stimulating agents. The elimination rates of 125I-labelled T4 and T3 were unaffected by somatostatin. The observations suggests that somatostatin may participate in the regulation of thyroid hormone secretion, by an inhibitory effect exerted within the thyroid gland. PMID:199013

Ahrén, B; Hedner, P; Melander, A; Westgren, U

1977-10-01

44

Heat shock response of Saccharomyces cerevisiae mutants altered in cyclic AMP-dependent protein phosphorylation.  

PubMed Central

When Saccharomyces cerevisiae cells grown at 23 degrees C were transferred to 36 degrees C, they initiated synthesis of heat shock proteins, acquired thermotolerance to a lethal heat treatment given after the temperature shift, and arrested their growth transiently at the G1 phase of the cell division cycle. The bcy1 mutant which resulted in production of cyclic AMP (cAMP)-independent protein kinase did not synthesize the three heat shock proteins hsp72A, hsp72B, and hsp41 after the temperature shift. The bcy1 cells failed to acquire thermotolerance to the lethal heat treatment and were not arrested at the G1 phase after the temperature shift. In contrast, the cyr1-2 mutant, which produced a low level of cAMP, constitutively produced three heat shock proteins and four other proteins without the temperature shift and was resistant to the lethal heat treatment. The results suggest that a decrease in the level of cAMP-dependent protein phosphorylation results in the heat shock response, including elevated synthesis of three heat shock proteins, acquisition of thermotolerance, and transient arrest of the cell cycle. Images

Shin, D Y; Matsumoto, K; Iida, H; Uno, I; Ishikawa, T

1987-01-01

45

Apparent presence of Ser133-phosphorylated cyclic AMP response element binding protein (pCREB) in brain mitochondria is due to cross-reactivity of pCREB antibodies with pyruvate dehydrogenase  

Microsoft Academic Search

Cyclic AMP response element binding protein (CREB) is a constitutive transcription factor that activates transcription following stimulus-dependent phosphorylation at Ser133, implicated in synaptic plasticity and neuronal survival path- ways. The prevailing view that CREB is exclusively nuclear has been questioned by several studies, and, for example, mitochondrial localization has been reported. Using subcel- lular fractionation of rat brain cortex coupled

Jan Platenik; Vladimir J. Balcar; Yukio Yoneda; Barbara Mioduszewska; Richard Buchal; Radovan Hynek; Lukasz Kilianek; Nobuyuki Kuramoto; Grzegorz Wilczynski; Kiyokazu Ogita; Yoichi Nakamura; Leszek Kaczmarek

2005-01-01

46

Histamine H1-agonist potentiation of adenosine-stimulated cyclic AMP accumulation in slices of guinea-pig cerebral cortex: comparison of response and binding parameters.  

PubMed Central

1 A range of histamine analogues have been examined as potentiators of the adenosine-stimulated accumulation of cyclic adenosine 3',5'-monophosphate (cyclic AMP) in slices of guinea-pig cerebral cortex. Dose-response curves were constructed for the 6 most active compounds and characterized in terms of the IC50, the slope and the maximum response attainable relative to that of histamine. 2 Histamine, 2-thiazolylethylamine and N alpha-methylhistamine produced a maximal or near maximal response. N alpha, N alpha-dimethylhistamine and 2-methylhistamine appear to be partial agonists. 3 The response to all the agonists was practically abolished by mepyramine 1 microM, indicating that the response is mediated largely or wholly via histamine H1-receptors. 4 The relative potencies of the agonists on cyclic AMP accumulation were in general similar to relative potencies in causing contraction of intestinal smooth muscle. The biggest difference was observed with N alpha-methylhistamine. 5 The histamine analogues were also examined as inhibitors of [3H]-mepyramine binding in homogenates of guinea-pig cerebral cortex. The inhibition curves were characterized in terms of IC50, the slope and the maximum percentage inhibition. This last value was compared with the inhibition produced by promethazine 2 microM. 6 For the 6 most potent agonists, the EC50 for cyclic AMP accumulation was compared with the IC50 against [3H]-mepyramine binding, corrected for inhibition of non-receptor binding and for competition with [3H]-mepyramine. With the possible exception of 2-pyridylethylamine, the values did not differ by more than a factor of 3.

Daum, P. R.; Hill, S. J.; Young, J. M.

1982-01-01

47

Structural overview on the allosteric activation of cyclic AMP receptor protein.  

PubMed

Cyclic AMP receptor protein (CRP) is a prokaryotic global transcription regulator that controls the expression of nearly 200 genes. The protein, allosterically activated by cAMP binding, binds to DNA and interacts with RNA polymerase. Current understanding on the allosteric process of the Escherichia coli CRP activation can be summarized into a rigid-body movement that involves subunit realignment and domain rearrangement. The main consequence of that overall transition is protrusion and adjustment of F-helices that recognize specific DNA sites. Although physicochemical and structural studies during the past decades have contributed to a comprehensive understanding of the CRP allostery, a paucity of structural information about the cAMP-free form (apo-CRP) has precluded a definite elucidation of the allosterism. In this respect, recent achievements of structures on other CRP-family proteins provide useful information to fill in the details of the allosteric transition of CRP. Thus, in this paper, accomplishments of CRP-family structures are summarized and inspected comparatively with new findings. This review not only provides a structural overview on the allosteric conformational change of CRP but also suggests a thoughtful discussion about unsolved issues or conflicting arguments. Solving those issues and the apo-CRP structure would enable us to finally define the CRP allostery. PMID:19439203

Won, Hyung-Sik; Lee, Yoo-Sup; Lee, Sung-Hee; Lee, Bong-Jin

2009-05-09

48

Enhanced phosphorylation of cyclic AMP response element binding protein in Brain of mice following repetitive hypoxic exposure  

SciTech Connect

Cerebral ischemic/hypoxic preconditioning (I/HPC) is a phenomenon of endogenous protection that renders Brain tolerant to sustained ischemia/hypoxia. This profound protection induced by I/HPC makes it an attractive target for developing potential clinical therapeutic approaches. However, the molecular mechanism of I/HPC is unclear. Cyclic AMP (cAMP) response element binding protein (CREB), a selective nuclear transcriptional factor, plays a key role in the neuronal functions. Phosphorylation of CREB on Ser-133 may facilitate its transcriptional activity in response to various stresses. In the current study, we observed the changes in CREB phosphorylation (Ser-133) and protein expression in Brain of auto-hypoxia-induced HPC mice by using Western blot analysis. We found that the levels of phosphorylated CREB (Ser-133), but not protein expression of CREB, increased significantly (p < 0.05) in the hippocampus and the frontal cortex of mice after repetitive hypoxic exposure (H2-H4, n = 6 for each group), when compared to that of the normoxic (H0, n = 6) or hypoxic exposure once group (H1, n = 6). In addition, a significant enhancement (p < 0.05) of CREB phosphorylation (Ser-133) could also be found in the nuclear extracts from the whole hippocampus of hypoxic preconditioned mice (H2-H4, n = 6 for each group). These results suggest that the phosphorylation of CREB might be involved in the development of cerebral hypoxic preconditioning.

Gao Yanan [Institute for Biomedical Science of Pain, Beijing Key Laboratory for Neural Regeneration and Repairing, Department of Neurobiology, Capital University of Medical Sciences, No. 10 You AnMen Wai Xi Tou Tiao, Beijing 100054 (China); Gao Ge [Institute for Biomedical Science of Pain, Beijing Key Laboratory for Neural Regeneration and Repairing, Department of Neurobiology, Capital University of Medical Sciences, No. 10 You AnMen Wai Xi Tou Tiao, Beijing 100054 (China); Long Caixia [Institute for Biomedical Science of Pain, Beijing Key Laboratory for Neural Regeneration and Repairing, Department of Neurobiology, Capital University of Medical Sciences, No. 10 You AnMen Wai Xi Tou Tiao, Beijing 100054 (China); Han Song [Institute for Biomedical Science of Pain, Beijing Key Laboratory for Neural Regeneration and Repairing, Department of Neurobiology, Capital University of Medical Sciences, No. 10 You AnMen Wai Xi Tou Tiao, Beijing 100054 (China); Zu Pengyu [Institute for Biomedical Science of Pain, Beijing Key Laboratory for Neural Regeneration and Repairing, Department of Neurobiology, Capital University of Medical Sciences, No. 10 You AnMen Wai Xi Tou Tiao, Beijing 100054 (China); Fang Li [Division of Neurosurgery, Department of Surgery, Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0517 (United States)]. E-mail: lfang@utmb.edu; Li Junfa [Institute for Biomedical Science of Pain, Beijing Key Laboratory for Neural Regeneration and Repairing, Department of Neurobiology, Capital University of Medical Sciences, No. 10 You AnMen Wai Xi Tou Tiao, Beijing 100054 (China)]. E-mail: junfali@cpums.edu.cn

2006-02-10

49

Estrogen upregulates cyclic AMP response element modulator ? expression and downregulates interleukin-2 production by human T lymphocytes.  

PubMed

Systemic lupus erythematosus (SLE) is an autoimmune disease with a complex multifactorial pathogenesis. T lymphocytes play a critical role in disease pathogenesis and display abnormal gene expression and poor interleukin (IL)-2 production. We previously showed that the expression of the transcriptional repressor cyclic AMP response element modulator ? (CREM?) is increased in SLE T cells and contributes to reduced IL-2 production. Although estrogen is implicated in the onset and exacerbation of SLE, the precise nature of molecular events regulated by estrogen in immune cell function is not well understood. Here, we asked whether estrogen regulates the expression of CREM? in human T lymphocytes. We show that exposure of human T cells to 17-?-estradiol leads to a dose-dependent increase in CREM? mRNA expression, and this increase appears to be mediated through the estrogen receptors ? and ?. We show that the increased expression of CREM? is due to increased transcriptional activity of the CREM promoter and is mediated by increased expression and binding of the Sp1 transcriptional activator. We further show that estrogen treatment leads to a dose-dependent decrease in IL-2 mRNA and cytokine production by T cells. Finally, the effect of ?-estradiol on CREM? is observed more frequently in T cells from women than from men. We conclude that estrogen can modulate the expression of CREM? and lead to IL-2 suppression in human T lymphocytes, thus revealing a molecular link between hormones and the immune system in SLE. PMID:22281835

Moulton, Vaishali R; Holcomb, Dana R; Zajdel, Melissa C; Tsokos, George C

2012-05-09

50

Caffeine suppresses TNF-? production via activation of the cyclic AMP\\/protein kinase A pathway  

Microsoft Academic Search

This study investigated the effect of in vitro exposure to caffeine, and its major metabolite paraxanthine, at concentrations relevant to typical caffeine consumption in humans, on lipopolysaccharide (LPS)-stimulated cytokine production in human whole blood. In addition, a role for the cyclic AMP\\/protein kinase A (PKA) pathway in the immunomodulatory effect of caffeine was investigated. Diluted whole blood (taken following ?15

Louise A Horrigan; John P Kelly; Thomas J Connor

2004-01-01

51

Cyclic AMP enhances agonist-induced Ca2+ entry into endothelial cells by activation of potassium channels and membrane hyperpolarization.  

PubMed Central

The mechanism underlying cyclic AMP (cAMP)-mediated amplification of agonist-induced Ca2+ responses in endothelial cells was investigated in pig endothelial cells. Forskolin, adenosine and isoprenaline, as well as the membrane-permeant cAMP analogue dibutyryl cAMP, enhanced bradykinin-induced rises in intracellular free Ca2+ as well as bradykinin-induced Mn2+ entry. These agents were also found to hyperpolarize endothelial cells without increasing intracellular Ca2+ by itself, i.e. in the absence of bradykinin. Both amplification of bradykinin effects and the hyperpolarizing action was blocked by the protein kinase inhibitor H-8. The involvement of K+ channels in the hyperpolarizing effects of forskolin was consequently studied in perforated outside-out vesicles. Two different types of K+ channels were recorded, one of which had a large conductance (170 pS) and was activated by forskolin. We suggest that stimulation of endothelial adenylate cyclase results in activation of large-conductance K+ channels and consequently in membrane hyperpolarization, which in turn enhances bradykinin-induced entry of Ca2+ by increasing its electrochemical gradient.

Graier, W F; Kukovetz, W R; Groschner, K

1993-01-01

52

Lithium increases transcription factor binding to AP-1 and cyclic AMP-responsive element in cultured neurons and rat brain.  

PubMed

We have investigated whether lithium has effects on transcription factor binding to consensus DNA sequences of AP-1 and cyclic AMP-responsive element (CRE) in cultured rat neurons and in vivo. Treatment of rat cerebellar granule cells (CGC) with lithium chloride induced a concentration-dependent increase in AP-1 and CRE binding activities with maximal effects at therapeutically relevant concentrations of 0.5 and 1.0 mM. Time-course studies show that lithium's effects on AP-1 and CRE binding were biphasic within the first 24 h of treatment in immature CGC in culture and persistent in mature CGC, lasting as long as 7 days. These actions were concurrent with an increase in the mRNA levels of c-fos and c-jun, as well as the protein levels of c-Fos, c-Jun, and phosphorylated CRE binding protein (p-CREB). Gel supershift assays using transcription factor-specific antibodies revealed that p-CREB, Jun D, and a Fos family protein(s) are components of the AP-1 binding complex in untreated and lithium-treated CGC. Chronic dietary treatment of rats with lithium carbonate for 4 weeks also significantly increased AP-1 and CRE binding activity in the frontal cortex, hippocampus, amygdala, and cerebellum. Similar to the results obtained in CGC, p-CREB, Jun D, and Fos family proteins are present in the AP-1 binding sites in the frontal cortex and hippocampus of untreated and lithium-treated rats. Lithium-induced activation of transcription factor binding to AP-1 and CRE sites in vivo and in vitro provides a new avenue to study the mechanisms of action of lithium in the treatment of manic depressive illness. PMID:9375664

Ozaki, N; Chuang, D M

1997-12-01

53

The CytR repressor antagonizes cyclic AMP-cyclic AMP receptor protein activation of the deoCp2 promoter of Escherichia coli K-12.  

PubMed Central

We have investigated the regulation of the Escherichia coli deoCp2 promoter by the CytR repressor and the cyclic AMP (cAMP) receptor protein (CRP) complexed to cAMP. Promoter regions controlled by these two proteins characteristically contain tandem cAMP-CRP binding sites. Here we show that (i) CytR selectively regulated cAMP-CRP-dependent initiations, although transcription started from the same site in deoCp2 in the absence or presence of cAMP-CRP; (ii) deletion of the uppermost cAMP-CRP target (CRP-2) resulted in loss of CytR regulation, but had only a minor effect on positive control by the cAMP-CRP complex; (iii) introduction of point mutations in either CRP target resulted in loss of CytR regulation; and (iv) regulation by CytR of deletion mutants lacking CRP-2 could be specifically reestablished by increasing the intracellular concentration of CytR. These findings indicate that both CRP targets are required for efficient CytR repression of deoCp2. Models for the action of CytR are discussed in light of these findings. Images

S?gaard-Andersen, L; Martinussen, J; M?llegaard, N E; Douthwaite, S R; Valentin-Hansen, P

1990-01-01

54

Nuclear localization of v-Abl leads to complex formation with cyclic AMP response element (CRE)-binding protein and transactivation through CRE motifs.  

PubMed Central

Deregulated expression of v-abl and BCR/abl genes has been associated with myeloproliferative syndromes and myelodysplasia, both of which can progress to acute leukemia. These studies identify the localization of the oncogenic form of the abl gene product encoded by the Abelson murine leukemia virus in the nuclei of myeloid cells and the association of the v-Abl protein with the transcriptional regulator cyclic AMP response element-binding protein (CREB). We have mapped the specific domains within each of the proteins responsible for this interaction. We have shown that complex formation is a prerequisite for transcriptional potentiation of CREB. Transient overexpression of the homologous cellular protein c-Abl also results in the activation of promoters containing an intact CRE. These observations identify a novel function for v-Abl, that of a transcriptional activator that physically interacts with a transcription factor.

Birchenall-Roberts, M C; Ruscetti, F W; Kasper, J J; Bertolette, D C; Yoo, Y D; Bang, O S; Roberts, M S; Turley, J M; Ferris, D K; Kim, S J

1995-01-01

55

A simple electrostatic switch important in the activation of type I protein kinase A by cyclic AMP  

PubMed Central

Cyclic AMP activates protein kinase A by binding to an inhibitory regulatory (R) subunit and releasing inhibition of the catalytic (C) subunit. Even though crystal structures of regulatory and catalytic subunits have been solved, the precise molecular mechanism by which cyclic AMP activates the kinase remains unknown. The dynamic properties of the cAMP binding domain in the absence of cAMP or C-subunit are also unknown. Here we report molecular-dynamics simulations and mutational studies of the RI? R-subunit that identify the C-helix as a highly dynamic switch which relays cAMP binding to the helical C-subunit binding regions. Furthermore, we identify an important salt bridge which links cAMP binding directly to the C-helix that is necessary for normal activation. Additional mutations show that a hydrophobic “hinge” region is not as critical for the cross-talk in PKA as it is in the homologous EPAC protein, illustrating how cAMP can control diverse functions using the evolutionarily conserved cAMP-binding domains.

Vigil, Dominico; Lin, Jung-Hsin; Sotriffer, Christoph A.; Pennypacker, Juniper K.; McCammon, J. Andrew; Taylor, Susan S.

2006-01-01

56

A simple electrostatic switch important in the activation of type I protein kinase A by cyclic AMP.  

PubMed

Cyclic AMP activates protein kinase A by binding to an inhibitory regulatory (R) subunit and releasing inhibition of the catalytic (C) subunit. Even though crystal structures of regulatory and catalytic subunits have been solved, the precise molecular mechanism by which cyclic AMP activates the kinase remains unknown. The dynamic properties of the cAMP binding domain in the absence of cAMP or C-subunit are also unknown. Here we report molecular-dynamics simulations and mutational studies of the RIalpha R-subunit that identify the C-helix as a highly dynamic switch which relays cAMP binding to the helical C-subunit binding regions. Furthermore, we identify an important salt bridge which links cAMP binding directly to the C-helix that is necessary for normal activation. Additional mutations show that a hydrophobic "hinge" region is not as critical for the cross-talk in PKA as it is in the homologous EPAC protein, illustrating how cAMP can control diverse functions using the evolutionarily conserved cAMP-binding domains. PMID:16322564

Vigil, Dominico; Lin, Jung-Hsin; Sotriffer, Christoph A; Pennypacker, Juniper K; McCammon, J Andrew; Taylor, Susan S

2005-12-01

57

Psychoactive drug effects on a system which generates cyclic AMP in brain  

Microsoft Academic Search

RECENTLY a direct correlation has been reported between spontaneous motor activity, tyrosine hydroxylase activity and the responsiveness of the noradrenaline sensitive cyclic AMP-generating system in rat brain1,2. These observations may indicate that the turnover and\\/or level of noradrenaline in the brain is important in determining the sensitivity of the cyclic AMP-generating system to noradrenaline. Indeed, it has been shown that

Joachim Schultz

1976-01-01

58

Involvement of the cyclic AMP-responsive element binding protein in bovine leukemia virus expression in vivo.  

PubMed Central

The TAR element (Tax-responsive element; also called TxRE) is a major determinant of the regulation of bovine leukemia virus (BLV) expression. In order to gain insight into the mechanisms of viral expression, complexes formed between proteins and the TAR enhancer DNA were analyzed by gel retardation assays. We report here that nuclear lysates from ex vivo-isolated B lymphocytes contain proteins that specifically bind to TAR. An antibody directed toward the cyclic AMP-responsive element binding (CREB) protein supershifted a complex (C1) present only in BLV-infected B lymphocytes. The CREB protein thus appears to be a major transcription factor involved in BLV expression in vivo. Images

Adam, E; Kerkhofs, P; Mammerickx, M; Kettmann, R; Burny, A; Droogmans, L; Willems, L

1994-01-01

59

A cyclic AMP-responsive DNA-binding protein (CREB2) is a cellular transactivator of the bovine leukemia virus long terminal repeat.  

PubMed

To gain insight into the cellular regulation of bovine leukemia virus (BLV) trans activation, a lambda-gt11 cDNA library was constructed with mRNA isolated from a BLV-induced tumor and the recombinant proteins were screened with an oligonucleotide corresponding to the tax activation-responsive element (TAR). Two clones (called TAR-binding protein) were isolated from 750,000 lambda-gt11 plaques. The binding specificity was confirmed by Southwestern (DNA-protein) and gel retardation assays. Nucleotide sequence analysis revealed that TAR-binding protein is very similar to the CREB2 protein. It contains a leucine zipper structure required for dimerization, a basic amino acid domain, and multiple potential phosphorylation sites. A vector expressing CREB2 was transfected into D17 osteosarcoma cells. In the absence of the tax transactivator, the CREB2 protein and the cyclic AMP-dependent protein kinase A activate the BLV long terminal repeat at a basal expression level: trans activation reached 10% of the values obtained in the presence of tax alone. These data demonstrate that CREB2 is a cellular factor able to induce BLV long terminal repeat expression in the absence of tax protein and could thus be involved in the early stages of viral infection. In addition, we observed that in vitro tax-induced trans activation can be activated or inhibited by CREB2 depending on the presence or absence of protein kinase A. These data suggest that the cyclic AMP pathway plays a role in the regulation of viral expression in BLV-infected animals. PMID:1309910

Willems, L; Kettmann, R; Chen, G; Portetelle, D; Burny, A; Derse, D

1992-02-01

60

Cyclic AMP in prokaryotes.  

PubMed Central

Cyclic AMP (cAMP) is found in a variety of prokaryotes including both eubacteria and archaebacteria. cAMP plays a role in regulating gene expression, not only for the classic inducible catabolic operons, but also for other categories. In the enteric coliforms, the effects of cAMP on gene expression are mediated through its interaction with and allosteric modification of a cAMP-binding protein (CRP). The CRP-cAMP complex subsequently binds specific DNA sequences and either activates or inhibits transcription depending upon the positioning of the complex relative to the promoter. Enteric coliforms have provided a model to explore the mechanisms involved in controlling adenylate cyclase activity, in regulating adenylate cyclase synthesis, and in performing detailed examinations of CRP-cAMP complex-regulated gene expression. This review summarizes recent work focused on elucidating the molecular mechanisms of CRP-cAMP complex-mediated processes. For other bacteria, less detail is known. cAMP has been implicated in regulating antibiotic production, phototrophic growth, and pathogenesis. A role for cAMP has been suggested in nitrogen fixation. Often the only data that support cAMP involvement in these processes includes cAMP measurement, detection of the enzymes involved in cAMP metabolism, or observed effects of high concentrations of the nucleotide on cell growth.

Botsford, J L; Harman, J G

1992-01-01

61

Activation of Protein Kinase C? by EPAC1 Is Required for the ERK- and CCAAT/Enhancer-binding Protein ?-dependent Induction of the SOCS-3 Gene by Cyclic AMP in COS1 Cells*  

PubMed Central

We recently found that induction of the anti-inflammatory SOCS-3 gene by cyclic AMP occurs through novel cyclic AMP-dependent protein kinase-independent mechanisms involving activation of CCAAT/enhancer-binding protein (C/EBP) transcription factors, notably C/EBP?, by the cyclic AMP GEF EPAC1 and the Rap1 GTPase. In this study we show that down-regulation of phospholipase (PL) C? with small interfering RNA or blockade of PLC activity with chemical inhibitors ablates exchange protein directly activated by cyclic AMP (EPAC)-dependent induction of SOCS-3 in COS1 cells. Consistent with this, stimulation of cells with 1-oleoyl-2-acetyl-sn-glycerol and phorbol 12-myristate 13-acetate, both cell-permeable analogues of the PLC product diacylglycerol, are sufficient to induce SOCS-3 expression in a Ca2+-dependent manner. Moreover, the diacylglycerol- and Ca2+-dependent protein kinase C (PKC) isoform PKC? becomes activated following cyclic AMP elevation or EPAC stimulation. Conversely, down-regulation of PKC activity with chemical inhibitors or small interfering RNA-mediated depletion of PKC? or -? blocks EPAC-dependent SOCS-3 induction. Using the MEK inhibitor U0126, we found that activation of ERK MAPKs is essential for SOCS-3 induction by either cyclic AMP or PKC. C/EBP? is known to be phosphorylated and activated by ERK. Accordingly, we found ERK activation to be essential for cyclic AMP-dependent C/EBP activation and C/EBP?-dependent SOCS-3 induction by cyclic AMP and PKC. Moreover, overexpression of a mutant form of C/EBP? (T235A), which lacks the ERK phosphorylation site, blocks SOCS-3 induction by cyclic AMP and PKC in a dominant-negative manner. Together, these results indicate that EPAC mediates novel regulatory cross-talk between the cyclic AMP and PKC signaling pathways leading to ERK- and C/EBP?-dependent induction of the SOCS-3 gene.

Borland, Gillian; Bird, Rebecca J.; Palmer, Timothy M.; Yarwood, Stephen J.

2009-01-01

62

Regional profiles of steady-state levels of cyclic nucleotides, cyclic AMP phosphodiesterase, and guanylate cyclase activities during late stages of unilateral ischemia in gerbil forebrain.  

PubMed

The present study was an extension of earlier work regarding the role of cyclic nucleotides and related enzymes during cerebral ischemia in the gerbil. Following unilateral carotid occlusion, levels of cyclic AMP and cyclic GMP were measured in four rapidly inactivated brain regions at 3, 6, and 24 hr after permanent occlusion and at 2 hr of occlusion plus 1 hr of reflow. An analysis of variance indicated significant minor fluctuations in the steady-state levels of the two cyclic nucleotides within the frontal cortex, the hippocampus, the striatum, and especially the olfactory tubercle with respect to occlusion time (3 and 24 hr) but not when comparing control vs ischemic hemispheres (except at 3 hr). Changes occurred only in animals developing neurological symptoms of ischemia. At 24 hr postocclusion the specific activity of the low-Km form of cyclic AMP phosphodiesterase was elevated especially on the ischemic side when determined in homogenates of the four brain regions. Alternatively, the high-Km form of the enzyme in the presence or absence of Ca2+-calmodulin was unchanged. Guanylate cyclase activity in tissue homogenates was not influenced by the conditions of ischemia until 24 hr had elapsed, an event likewise unique to symptomatic gerbils. The sensitivity of the enzyme to hematin-catalase was decreased in the ischemic hemispheres of the hippocampus, striatum, and olfactory tubercle. In addition, further activation of the hematin-catalase response by NaN3 was depressed in the ischemic side of the hippocampus and striatum. Taken together these and previous studies indicate that fluctuations in the steady-state levels of cyclic nucleotides that occur rather prominently during acute and to a lesser degree during prolonged ischemia are not correlated with associated changes in enzymes responsible for their synthesis and/or degradation. PMID:2906108

Palmer, G C; Christie-Pope, B C; Medina, M A; Colombo, P M; Palmer, S J

1988-09-01

63

Imidazolines inhibit secretory responses of rat colonic mucosa to calcium-dependent but not cyclic AMP-dependent secretagogues.  

PubMed

The purpose of this study was to investigate whether imidazolines have an anti-secretory action on intestinal epithelial cells. Muscle-stripped preparations of rat colon and monolayers of T84 human colonic epithelial cells were set up in Ussing chambers for measurement of short-circuit current. In rat colon acetylcholine, histamine, vasoactive intestinal polypeptide and forskolin elicited secretory responses which were recorded as increases in short-circuit current. Secretory responses to acetylcholine were inhibited in a concentration-dependent manner by the imidazolines phentolamine, idazoxan and clonidine. The effect of clonidine was not reversed by pre-incubation of mucosal preparations with yohimbine. Secretory responses to vasoactive intestinal polypeptide were unaffected by the three imidazolines. Phentolamine reduced responses of colonic mucosa to histamine but had no effect on responses to forskolin. Responses to vasoactive intestinal polypeptide and forskolin were significantly reduced in the presence of barium. In T84 cell monolayers phentolamine significantly reduced responses to acetylcholine. Three imidazolines, two with alpha-adrenoceptor-antagonist properties and one with alpha-agonist properties, have anti-secretory effects in rat colonic mucosal preparations. The anti-secretory action appears to discriminate between calcium-dependent and cyclic AMP-dependent secretagogues, inhibiting the former but not the latter. PMID:11273018

Anderson, M; Burleigh, D

2001-02-01

64

Effects of histamine and activators of the cyclic AMP system on protein synthesis in and release of high molecular weight glycoproteins from isolated gastric non-parietal cells.  

PubMed Central

1. Glycoprotein and protein synthesis in and release from pig isolated, enriched gastric mucous cells were measured by the incorporation of N-acetyl-[14C]-D-glucosamine and [3H]-L-leucine, respectively, into cellular and released acid precipitable material. 2. Histamine and activators of the adenosine 3':5'-cyclic monophosphate (cyclic AMP) system maximally stimulated total protein and glycoprotein synthesis in and release from the cells at concentrations of histamine (10 microM), forskolin (10-100 microM), 3-isobutyl-1-methylxanthine (100 microM), and dibutyryl cyclic AMP (1-3 mM), respectively. In the presence of 3-isobutyl-1-methylxanthine (30 microM) histamine stimulation was enhanced. 3. As shown by gel chromatography, stimulation by histamine (100 microM), forskolin (10 microM), 3-isobutyl-1-methylxanthine (100 microM) and dibutyryl cyclic AMP (1 mM) resulted in a release of high molecular weight (approximately 2 x 10(6) daltons) glycoproteins from the cells. The histamine H2-receptor antagonist, ranitidine (100 microM), blocked the effect of histamine. 4. We conclude that cyclic AMP-dependent processes are involved in the regulation of protein and glycoprotein synthesis in and the release of high molecular weight (mucous) glycoproteins from pig gastric non-parietal cells and that histamine may be a physiological activator of this system.

Heim, H. K.; Oestmann, A.; Sewing, K. F.

1991-01-01

65

Effects of histamine and activators of the cyclic AMP system on protein synthesis in and release of high molecular weight glycoproteins from isolated gastric non-parietal cells.  

PubMed

1. Glycoprotein and protein synthesis in and release from pig isolated, enriched gastric mucous cells were measured by the incorporation of N-acetyl-[14C]-D-glucosamine and [3H]-L-leucine, respectively, into cellular and released acid precipitable material. 2. Histamine and activators of the adenosine 3':5'-cyclic monophosphate (cyclic AMP) system maximally stimulated total protein and glycoprotein synthesis in and release from the cells at concentrations of histamine (10 microM), forskolin (10-100 microM), 3-isobutyl-1-methylxanthine (100 microM), and dibutyryl cyclic AMP (1-3 mM), respectively. In the presence of 3-isobutyl-1-methylxanthine (30 microM) histamine stimulation was enhanced. 3. As shown by gel chromatography, stimulation by histamine (100 microM), forskolin (10 microM), 3-isobutyl-1-methylxanthine (100 microM) and dibutyryl cyclic AMP (1 mM) resulted in a release of high molecular weight (approximately 2 x 10(6) daltons) glycoproteins from the cells. The histamine H2-receptor antagonist, ranitidine (100 microM), blocked the effect of histamine. 4. We conclude that cyclic AMP-dependent processes are involved in the regulation of protein and glycoprotein synthesis in and the release of high molecular weight (mucous) glycoproteins from pig gastric non-parietal cells and that histamine may be a physiological activator of this system. PMID:1724626

Heim, H K; Oestmann, A; Sewing, K F

1991-10-01

66

Outer Dynein Arm Light Chain 1 Is Essential for Controlling the Ciliary Response to Cyclic AMP in Paramecium tetraurelia  

PubMed Central

The individual role of the outer dynein arm light chains in the molecular mechanisms of ciliary movements in response to second messengers, such as Ca2+ and cyclic nucleotides, is unclear. We examined the role of the gene termed the outer dynein arm light chain 1 (LC1) gene of Paramecium tetraurelia (ODAL1), a homologue of the outer dynein arm LC1 gene of Chlamydomonas reinhardtii, in ciliary movements by RNA interference (RNAi) using a feeding method. The ODAL1-silenced (ODAL1-RNAi) cells swam slowly, and their swimming velocity did not increase in response to membrane-hyperpolarizing stimuli. Ciliary movements on the cortical sheets of ODAL1-RNAi cells revealed that the ciliary beat frequency was significantly lower than that of control cells in the presence of ?1 mM Mg2+-ATP. In addition, the ciliary orientation of ODAL1-RNAi cells did not change in response to cyclic AMP (cAMP). A 29-kDa protein phosphorylated in a cAMP-dependent manner in the control cells disappeared in the axoneme of ODAL1-RNAi cells. These results indicate that ODAL1 is essential for controlling the ciliary response by cAMP-dependent phosphorylation.

Kutomi, Osamu; Hori, Manabu; Ishida, Masaki; Tominaga, Takashi; Kamachi, Hiroyuki; Koll, France; Cohen, Jean; Yamada, Norico

2012-01-01

67

Outer dynein arm light chain 1 is essential for controlling the ciliary response to cyclic AMP in Paramecium tetraurelia.  

PubMed

The individual role of the outer dynein arm light chains in the molecular mechanisms of ciliary movements in response to second messengers, such as Ca(2+) and cyclic nucleotides, is unclear. We examined the role of the gene termed the outer dynein arm light chain 1 (LC1) gene of Paramecium tetraurelia (ODAL1), a homologue of the outer dynein arm LC1 gene of Chlamydomonas reinhardtii, in ciliary movements by RNA interference (RNAi) using a feeding method. The ODAL1-silenced (ODAL1-RNAi) cells swam slowly, and their swimming velocity did not increase in response to membrane-hyperpolarizing stimuli. Ciliary movements on the cortical sheets of ODAL1-RNAi cells revealed that the ciliary beat frequency was significantly lower than that of control cells in the presence of ? 1 mM Mg(2+)-ATP. In addition, the ciliary orientation of ODAL1-RNAi cells did not change in response to cyclic AMP (cAMP). A 29-kDa protein phosphorylated in a cAMP-dependent manner in the control cells disappeared in the axoneme of ODAL1-RNAi cells. These results indicate that ODAL1 is essential for controlling the ciliary response by cAMP-dependent phosphorylation. PMID:22427431

Kutomi, Osamu; Hori, Manabu; Ishida, Masaki; Tominaga, Takashi; Kamachi, Hiroyuki; Koll, France; Cohen, Jean; Yamada, Norico; Noguchi, Munenori

2012-03-16

68

20?-hydroxysteroid dehydrogenase gene promoter: potential role for cyclic AMP and xenobiotic responsive elements.  

PubMed

Teleostean 20?-hydroxysteroid dehydrogenase (20?-HSD) is involved in final oocyte maturation and steroid hormone metabolism. It has structural and functional similarities to mammalian carbonyl reductases that are involved in the metabolism of endogenous carbonyl and xenobiotic compounds. To understand the transcriptional regulation of 20?-HSD, here we report the cloning of 20?-HSD promoter from two fish species, rainbow trout and air-breathing catfish. Analysis of the promoter motifs, in silico identified the presence of several sites for transcription factor binding including cAMP, xenobiotic and steroid hormone responsive elements. Luciferase reporter assays with progressive deletion constructs demonstrated that 20?-HSD type B of trout has no promoter activity while 20?-HSD type A of trout and catfish 20?-HSD promoters showed basal promoter activity. A TATA box flanked by a CAAT box is important for basal transcription. Deletion of cAMP responsive element in the promoter decreased basal promoter activity significantly. Reporter assays with forskolin and IBMX, drugs that increase intracellular cAMP induced the promoter activity over the basal level. Intriguingly, ?-nafthoflavone, an arylhydrocarbon receptor ligand, induced the 20?-HSD promoter activity and is further evidenced by the induction of 20?-HSD expression in the livers of catfish, in vivo. These results demonstrate for the first time that 20?-HSD expression is not only modulated by cAMP but also by xenobiotics and further studies may provide significance to the ubiquitous distribution and broad substrate specificity of this enzyme. PMID:22835697

Sreenivasulu, G; Senthilkumaran, B; Sudhakumari, C C; Guan, G; Oba, Y; Kagawa, H; Nagahama, Y

2012-07-23

69

Calspermin gene transcription is regulated by two cyclic AMP response elements contained in an alternative promoter in the calmodulin kinase IV gene.  

PubMed Central

The transcript for the high-affinity Ca2+/calmodulin-binding protein calspermin is generated from the gene encoding Ca2+/calmodulin-dependent protein kinase IV only in postmeiotic germ cells during spermatogenesis. We demonstrate that this testis-specific calspermin transcript can be produced in heterologous cells by utilization of a promoter located in an intron of the calmodulin (CaM) kinase IV gene. Critical motifs within this promoter are two cyclic AMP response element (CRE)-like sequences located about -70 and -50 bp upstream of the transcriptional initiation site. Both CRE motifs are footprinted by the authentic testis-specific transcriptional activator CREM tau or by CREM tau present in adult testis nuclear extract. Whereas a 2.1-kb DNA fragment containing the calspermin promoter is inactive when transfected into NIH 3T3 cells, activity can be restored by cotransfection of CREM tau and protein kinase A or CaM kinase IV but not CaM kinase II alpha. Restoration of activity is greatly reduced by mutation of the two CRE motifs. Since CRE-like motifs have been identified in many genes uniquely expressed in postmeiotic germ cells, which contain abundant CREM tau protein, we suggest that CREM tau may function as one transcription factor responsible for the expression of postmeiotic germ cell-specific genes.

Sun, Z; Sassone-Corsi, P; Means, A R

1995-01-01

70

Direct transcriptional control of the plasminogen activator gene of Yersinia pestis by the cyclic AMP receptor protein.  

PubMed

Horizontal gene transfer events followed by proper regulatory integration of a gene drive rapid evolution of bacterial pathogens. A key event in the evolution of the highly virulent plague bacterium Yersinia pestis was the acquisition of plasmid pPCP1, which carries the plasminogen activator gene, pla. This promoted the bubonic form of the disease by increasing bacterial dissemination from flea bite sites and incidentally enhanced replication in respiratory airways during pneumonic infection. We determined that expression of pla is controlled by the global regulator cyclic AMP (cAMP) receptor protein (Crp). This transcription factor is well conserved among distantly related bacteria, where it acts as a soluble receptor for the ubiquitous signaling molecule cAMP and controls a global network of metabolic and stress-protective genes. Crp has a similar physiological role in Y. pestis since loss of its function resulted in an inability to metabolize a variety of nonglucose substrates. Activation of pla expression requires a transcription activation element of the pla promoter that serves as a Crp binding site. Crp interaction with this site was demonstrated to occur only in the presence of cAMP. Alteration of the Crp binding site nucleotide sequence prevented in vitro formation of Crp-DNA complexes and inhibited in vivo expression of pla. The placement of pla under direct regulatory control of Crp highlights how highly adapted pathogens integrate laterally acquired genes to coordinate virulence factor expression with global gene networks to maintain homeostasis through the infectious life cycle. PMID:17933899

Kim, Tae-Jong; Chauhan, Sadhana; Motin, Vladimir L; Goh, Ee-Been; Igo, Michele M; Young, Glenn M

2007-10-12

71

Interplay of the E box, the cyclic AMP response element, and HTF4/HEB in transcriptional regulation of the neurospecific, neurotrophin-inducible vgf gene.  

PubMed Central

vgf is a neurotrophin response-specific, developmentally regulated gene that codes for a neurosecretory polypeptide. Its transcription in neuronal cells is selectively activated by the neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor, and neurotrophin 3, which induce survival and differentiation, and not by epidermal growth factor. We studied a short region of the rat vgf promoter which is essential for its regulated expression. A cyclic AMP response element (CRE) within this region is necessary for NGF induction of vgf transcription. Two sites upstream of CRE, an E box and a CCAAT sequence, bind nuclear protein complexes and are involved in transcriptional control. The E box has a dual role. It acts as an inhibitor in NIH 3T3 fibroblasts, together with a second E box located downstream, and as a stimulator in the NGF-responsive cell line PC12. By expression screening, we have isolated the cDNA for a basic helix-loop-helix transcription factor, a homolog of the HTF4/HEB E protein, that specifically binds the vgf promoter E box. The E protein was present in various cell lines, including PC12 cells, and was a component of a multiprotein nuclear complex that binds the promoter in vitro. The E box and CRE cooperate in binding to this complex, which may be an important determinant for neural cell-specific expression.

Di Rocco, G; Pennuto, M; Illi, B; Canu, N; Filocamo, G; Trani, E; Rinaldi, A M; Possenti, R; Mandolesi, G; Sirinian, M I; Jucker, R; Levi, A; Nasi, S

1997-01-01

72

Cyclic AMP enhances TGF? responses of breast cancer cells by upregulating TGF? receptor I expression.  

PubMed

Cellular functions are regulated by complex networks of many different signaling pathways. The TGF? and cAMP pathways are of particular importance in tumor progression. We analyzed the cross-talk between these pathways in breast cancer cells in 2D and 3D cultures. We found that cAMP potentiated TGF?-dependent gene expression by enhancing Smad3 phosphorylation. Higher levels of total Smad3, as observed in 3D-cultured cells, blocked this effect. Two Smad3 regulating proteins, YAP (Yes-associated protein) and T?RI (TGF? receptor 1), were responsive to cAMP. While YAP had little effect on TGF?-dependent expression and Smad3 phosphorylation, a constitutively active form of T?RI mimicked the cAMP effect on TGF? signaling. In 3D-cultured cells, which show much higher levels of T?RI and cAMP, T?RI was unresponsive to cAMP. Upregulation of T?RI expression by cAMP was dependent on transcription. A proximal T?RI promoter fragment was moderately, but significantly activated by cAMP suggesting that cAMP increases T?RI expression at least partially by activating T?RI transcription. Neither the cAMP-responsive element binding protein (CREB) nor the T?RI-regulating transcription factor Six1 was required for the cAMP effect. An inhibitor of histone deacetylases alone or together with cAMP increased T?RI expression by a similar extent as cAMP alone suggesting that cAMP may exert its effect by interfering with histone acetylation. Along with an additive stimulatory effect of cAMP and TGF? on p21 expression an additive inhibitory effect of these agents on proliferation was observed. Finally, we show that mesenchymal stem cells that interact with breast cancer cells can simultaneously activate the cAMP and TGF? pathways. In summary, these data suggest that combined effects of cAMP and TGF?, as e.g. induced by mesenchymal stem cells, involve the upregulation of T?RI expression on the transcriptional level, likely due to changes in histone acetylation. As a consequence, cancer cell functions such as proliferation are affected. PMID:23349840

Oerlecke, Ilka; Bauer, Elke; Dittmer, Angela; Leyh, Benjamin; Dittmer, Jürgen

2013-01-18

73

Cyclic AMP Enhances TGF? Responses of Breast Cancer Cells by Upregulating TGF? Receptor I Expression  

PubMed Central

Cellular functions are regulated by complex networks of many different signaling pathways. The TGF? and cAMP pathways are of particular importance in tumor progression. We analyzed the cross-talk between these pathways in breast cancer cells in 2D and 3D cultures. We found that cAMP potentiated TGF?-dependent gene expression by enhancing Smad3 phosphorylation. Higher levels of total Smad3, as observed in 3D-cultured cells, blocked this effect. Two Smad3 regulating proteins, YAP (Yes-associated protein) and T?RI (TGF? receptor 1), were responsive to cAMP. While YAP had little effect on TGF?-dependent expression and Smad3 phosphorylation, a constitutively active form of T?RI mimicked the cAMP effect on TGF? signaling. In 3D-cultured cells, which show much higher levels of T?RI and cAMP, T?RI was unresponsive to cAMP. Upregulation of T?RI expression by cAMP was dependent on transcription. A proximal T?RI promoter fragment was moderately, but significantly activated by cAMP suggesting that cAMP increases T?RI expression at least partially by activating T?RI transcription. Neither the cAMP-responsive element binding protein (CREB) nor the T?RI-regulating transcription factor Six1 was required for the cAMP effect. An inhibitor of histone deacetylases alone or together with cAMP increased T?RI expression by a similar extent as cAMP alone suggesting that cAMP may exert its effect by interfering with histone acetylation. Along with an additive stimulatory effect of cAMP and TGF? on p21 expression an additive inhibitory effect of these agents on proliferation was observed. Finally, we show that mesenchymal stem cells that interact with breast cancer cells can simultaneously activate the cAMP and TGF? pathways. In summary, these data suggest that combined effects of cAMP and TGF?, as e.g. induced by mesenchymal stem cells, involve the upregulation of T?RI expression on the transcriptional level, likely due to changes in histone acetylation. As a consequence, cancer cell functions such as proliferation are affected.

Oerlecke, Ilka; Bauer, Elke; Dittmer, Angela; Leyh, Benjamin; Dittmer, Jurgen

2013-01-01

74

Bacillus anthracis Edema Toxin Suppresses Human Macrophage Phagocytosis and Cytoskeletal Remodeling via the Protein Kinase A and Exchange Protein Activated by Cyclic AMP Pathways  

Microsoft Academic Search

Bacillus anthracis, the etiological agent of anthrax, is a gram-positive spore-forming bacterium. It produces edema toxin (EdTx), a powerful adenylate cyclase that increases cyclic AMP (cAMP) levels in host cells. Because other cAMP-increasing agents inhibit key macrophage (M) functions, such as phagocytosis, it was hypothesized that EdTx would exhibit similar suppressive activities. Our previous GeneChip data showed that EdTx downregulated

Linsey A. Yeager; Ashok K. Chopra; Johnny W. Peterson

2009-01-01

75

Neural plasticity maintained high by activation of cyclic AMP-dependent protein kinase: an age-independent, general mechanism in cat striate cortex.  

PubMed

Adult cats lack ocular dominance plasticity, showing little change in the ocular dominance distribution following monocular deprivation. Ocular dominance plasticity is also lost in kitten visual cortex that has been continuously infused with either catecholaminergic neurotoxin, beta-adrenoreceptor blocker, or inhibitor of cyclic AMP-dependent protein kinase (protein kinase A). Complementarily, in adult cats we showed earlier that pharmacological activation of protein kinase A, albeit partially, restored ocular dominance plasticity. In the present study, we first asked whether, mediated by protein kinase A activation, the same molecular mechanisms could restore ocular dominance plasticity to kitten cortex that once lost the expression of plasticity due to prior pharmacological treatments. Concurrently with monocular deprivation, two kinds of cyclic AMP-related drugs (cholera toxin A-subunit or dibutyryl cyclic AMP) were directly infused in two types of aplastic kitten cortex pretreated with either 6-hydroxydopamine or propranolol. The combined treatment resulted in clear ocular dominance shift to the non-deprived eye, indicating that cortical plasticity was fully restored to aplastic kitten cortex. Next, to directly prove the sensitivity difference in protein kinase A activation between the immature and mature cortex, we compared the thus-obtained data in kittens with the published data derived from adult cats under the comparable experimental paradigm. The extent of ocular dominance changes following monocular deprivation was compared at different drug concentrations in the two preparations: the shifted ocular dominance distribution in aplastic kitten cortex infused with dibutyryl cyclic AMP at the lowest concentration tested and the W-shaped distribution in similarly treated adult cortex at a thousandfold-higher drug concentration that induced nearly maximal changes. We conclude that, irrespective of the animal's age, activation of protein kinase A cascades is a general mechanism to maintain ocular dominance plasticity high, their sensitivity being substantially higher in the immature than mature cortex. PMID:17544224

Imamura, K; Kasamatsu, T; Tanaka, S

2007-06-01

76

Type I adenylyl cyclase functions as a coincidence detector for control of cyclic AMP response element-mediated transcription: synergistic regulation of transcription by Ca2+ and isoproterenol.  

PubMed Central

Studies carried out with mammals and invertebrates suggest that Ca(2+)-sensitive adenylyl cyclases may be important for neuroplasticity. Long-term potentiation in the hippocampus requires increases in intracellular Ca2+ which are accompanied by elevated cyclic AMP (cAMP). Furthermore, activation of cAMP-dependent protein kinase is required for the late stage of long-term potentiation in the CA1 region of the hippocampus, which is also sensitive to inhibitors of transcription. Therefore, some forms of synaptic plasticity may require coordinate regulation of transcription by Ca2+ and cAMP. In this study, we demonstrate that the expression of type I adenylyl cyclase in HEK-293 cells allows Ca2+ to stimulate reporter gene activity mediated through the cAMP response element. Furthermore, simultaneous activation by Ca2+ and isoproterenol caused synergistic stimulation of transcription in HEK-293 cells and cultured neurons. We propose that Ca2+ and neurotransmitter stimulation of type I adenylyl cyclase may play a role in synaptic plasticity by generating optimal cAMP signals for regulation of transcription.

Impey, S; Wayman, G; Wu, Z; Storm, D R

1994-01-01

77

The 5-HT4 receptor subtype inhibits K+ current in colliculi neurones via activation of a cyclic AMP-dependent protein kinase.  

PubMed Central

1. The aim of the present study was to examine the effect of 5-hydroxytryptamine (5-HT) on K+ current in primary culture of mouse colliculi neurones and to identify the 5-HT receptor subtype that could be involved in this effect. 2. The voltage-activated K+ current of the neurones was partially blocked by 8-bromo adenosine 3':5'-cyclic monophosphate (8-bromo-cyclic AMP). This effect was mimicked by 5-HT and the action of 5-HT could be antagonized by H7, a non specific protein kinase inhibitor, and by PKI, the specific cyclic AMP-dependent protein kinase blocker. 3. A similar cyclic AMP-dependent blockade of the K+ current was found with renzapride (BRL 24,924) and other 5-HT4 receptor agonists such as cisapride, BIMU 8, zacopride and 5-methoxytryptamine (5-MeOT). ICS 205,930, the classical 5-HT4 receptor blocker, could not be used in this study because it inhibited the studied K+ current by itself. However, the novel 5-HT4 receptor antagonist, DAU 6285 blocked the effects of 5-HT and renzapride on the K+ current. 4. The current was insensitive to the 5-HT1 and 5-HT3 receptor agonists (8-hydroxy-2-(di-n-propylamino) tetralin, RU 24,969, carboxamidotryptamine, 2-CH3-5-HT) as well as to 5-HT1, 5-HT2 and 5-HT3 antagonists (methiothepin, ketanserin, ondansetron [GR 38,032]). Moreover, these antagonists did not affect the actions of the tested 5-HT4 receptor agonists. 5. The present results show that part of the voltage-activated K+ current in mouse colliculi neurones is cyclic AMP-sensitive and the blockade of the current by 5-HT involves the 5-HT4 receptor subtype.(ABSTRACT TRUNCATED AT 250 WORDS)

Fagni, L.; Dumuis, A.; Sebben, M.; Bockaert, J.

1992-01-01

78

Antiplatelet activity of Phellinus baummii methanol extract is mediated by cyclic AMP elevation and inhibition of collagen-activated integrin-?(IIb) ?? and MAP kinase.  

PubMed

Phellinus baumii is a mushroom that has been used as folk medicine against various diseases and is reported to have antidiabetic, anticancer, antioxidant, antiinflammatory and antihypertensive activities. However, information on the effects of P. baumii extract in platelet function is limited. Therefore, the aim of this study was to examine the impact of a P. baumii methanol extract (PBME) on platelet activation and to investigate the mechanism behind its antiplatelet activity. PBME effects on agonist-induced platelet aggregation, granule secretion, [Ca²?](i) mobilization, ?(IIb) ?? activation, cyclic AMP release and mitogen-activated protein kinase (MAPK) phosphorylations were studied using rat platelets. PBME dose-dependently inhibited collagen, thrombin and ADP-induced platelet aggregation with an IC?? of 51.0?±?2.4, 54.0?±?2.1 and 53.0?±?4.3??g/mL, respectively. Likewise, thrombin-induced [Ca²?](i) and collagen-activated ATP secretions were suppressed in PBME treated platelets. Aggregation and ATP secretion were also markedly attenuated by PBME alone or in combination with PP2 (Src inhibitor) and U-73122 (PLC inhibitor) in collagen-stimulated platelets. Besides, PBME treatment elevated basal cyclic AMP levels and inhibited collagen-induced integrin-?(IIb) ?? activation. Moreover, PBME attenuated extracellular-signal-regulated protein kinase 2 (ERK2) and c-Jun N-terminal kinase 1 (JNK1) phosphorylations. Further PD98059 (ERK inhibitor) and SP60025 (JNK inhibitor) reduced collagen-induced platelet aggregation and ATP secretion. In conclusion, the observed PBME antiplatelet activity may be mediated by activation of cyclic AMP and inhibition of ERK2 and JNK1 phosphorylations. Finally, these data suggest that PBME may have therapeutic potential for the treatment of cardiovascular diseases that involve aberrant platelet function. PMID:21394810

Kamruzzaman, S M; Endale, Mehari; Oh, Won-Jun; Park, Seung-Chun; Kim, Tae-Hwan; Lee, In-Kyoung; Cho, Jae Youl; Park, Hwa-Jin; Kim, Sang Keun; Yun, Bong-Sik; Rhee, Man Hee

2011-03-11

79

Prostaglandin E2 increases cyclic AMP and inhibits endothelin-1 production/secretion by guinea-pig tracheal epithelial cells through EP4 receptors  

PubMed Central

Prostaglandin E2 (PGE2) increased adenosine 3??:?5?-cyclic monophosphate (cyclic AMP) formation in tracheal epithelial cells and concomitantly decreased the production/secretion of immunoreactive endothelin (irET). Naturally occurring prostanoids and selective and non-selective EP receptor agonists showed the following rank order of potency in stimulating cyclic AMP generation by epithelial cells: PGE2 (EP-selective)>16,16-dimethyl PGE2 (EP-selective)>11-deoxy PGE2 (EP-selective)>>>iloprost (IP/EP1/EP3-selective), butaprost (EP2-selective), PGD2 (DP-selective), PGF2? (FP-selective). The lack of responsiveness of the latter prostanoids indicated that the prostanoid receptor present in these cells is not of the DP, FP, IP, EP1, EP2 or EP3 subtype. Pre-incubating the cells with the selective TP/EP4-receptor antagonists AH23848B and AH22921X antagonized the PGE2-evoked cyclic AMP generation. This suggested that EP4 receptors mediate PGE2 effects. However, in addition to any antagonistic effects at EP4-receptors, both compounds, to a different extent, modified cyclic AMP metabolism. The selective EP1, DP and EP2 receptor antagonist (AH6809) failed to inhibit PGE2-evoked cyclic AMP generation which confirmed that the EP2 receptor subtype did not contribute to the change in cyclic AMP formation in these cells. The PGE2-induced inhibition of irET production by guinea-pig tracheal epithelial cells was due to cyclic AMP generation and activation of the cyclic AMP-dependent protein kinase since this effect was reverted by the cyclic AMP antagonist Rp-cAMPS. These results provide the first evidence supporting the existence of a functional prostaglandin E2 receptor that shares the pharmacological features of the EP4-receptor subtype in guinea-pig tracheal epithelial cells. These receptors modulate cyclic AMP formation as well as ET-1 production/secretion in these cells.

Pelletier, Stephane; Dube, Jean; Villeneuve, Annie; Gobeil, Fernand; Yang, Quan; Battistini, Bruno; Guillemette, Gaetan; Sirois, Pierre

2001-01-01

80

Increased phosphorylation of cyclic AMP response element-binding protein in the spinal cord of Lewis rats with experimental autoimmune encephalomyelitis.  

PubMed

To investigate whether the phosphorylation of cyclic AMP response element-binding protein (CREB) is implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), the change in the level of CREB phosphorylation was analyzed in the spinal cord of Lewis rats with EAE. Western blot analysis showed that the phosphorylation of CREB in the spinal cord of rats increased significantly at the peak stage of EAE compared with the controls (p<0.05) and declined significantly in the recovery stage (p<0.05). Immunohistochemistry showed that the phosphorylated form of CREB (p-CREB) was constitutively immunostained in few astrocytes and dorsal horn neurons in the spinal cord of normal rats. In the EAE-affected spinal cord, p-CREB was mainly found in ED1-positive macrophages at the peak stage of EAE, and the number of p-CREB-immunopositive astrocytes was markedly increased in the spinal cord with EAE compared with the controls. Moreover, p-CREB immunoreactivity of sensory neurons, which are closely associated with neuropathic pain, was significantly increased in the dorsal horns at the peak stage of EAE. Based on these results, we suggest that the increased phosphorylation of CREB in EAE lesions was mainly attributable to the infiltration of inflammatory cells and astrogliosis, possibly activating gene transcription, and that its increase in the sensory neurons in the dorsal horns is involved in the generation of neuropathic pain in the rat EAE model. PMID:17617386

Kim, Heechul; Moon, Changjong; Ahn, Meejung; Lee, Yongduk; Kim, Seungjoon; Matsumoto, Yoh; Koh, Chang-Sung; Kim, Moon-Doo; Shin, Taekyun

2007-06-21

81

Responsiveness of Immature versus Adult Male Rat Hypothalami to Dibutyryl Cyclic AMP and Forskolin-Induced LHRH Release in vitro  

Microsoft Academic Search

In the present study, we have investigated the effects of intermittent dibutyryl cyclic AMP (dbcAMP, 5 × 10–8 M), butyrate (5 × 10–8 M) and forskolin (10–4 M) on immunoreactive luteinizing hormone-releasing hormone (LHRH) release from superfused hypothalamic fragments from intact male rats of age 25, 30, 45, or 60–75 day (adult). The results indicate that at 25 days of

Daryl E. Hartter; Victor D. Ramirez

1985-01-01

82

The Role of Spinal Cord Cyclic AMP in the Acoustic Startle Response in Rats  

Microsoft Academic Search

Drugs thought to increase intracellular levels of CAMP were infused intrathecally into the subarachnoid space of the lumbar spinal cord, and the effects on the acoustic startle response in rats were measured. Intrathecal infusions of the CAMP analogs dibutyryl CAMP or 8-bromo CAMP (12.5100 pg) produced marked, dose-dependent increases in startle amplitude com- pared to the infusion of artificial cerebrospinal

J. H. Kehne; E. Astrachan; J. F. Tallman; M. Davis; Abraham Ribicoff

83

Hepatitis C virus NS2 protein activates cellular cyclic AMP-dependent pathways  

SciTech Connect

Chronic infection of the hepatitis C virus (HCV) leads to liver cirrhosis and cancer. The mechanism leading to viral persistence and hepatocellular carcinoma, however, has not been fully understood. In this study, we show that the HCV infection activates cellular cAMP-dependent pathways. Expression of a luciferase reporter gene controlled by a basic promoter with the cAMP response element (CRE) was significantly elevated in human hepatoma Huh-7 cells infected with the HCV JFH1. Analysis with viral subgenomic replicons indicated that the HCV NS2 protein is responsible for the effect. Furthermore, the level of cellular transcripts whose stability is known to be regulated by cAMP was specifically reduced in cells harboring NS2-expressing replicons. These results allude to the HCV NS2 protein having a novel function of regulating cellular gene expression and proliferation through the cAMP-dependent pathway.

Kim, Kyoung Mi [School of Life Sciences and Biotechnology, Korea University, Seoul 136-701 (Korea, Republic of); Kwon, Shi-Nae [School of Life Sciences and Biotechnology, Korea University, Seoul 136-701 (Korea, Republic of); Kang, Ju-Il [School of Life Sciences and Biotechnology, Korea University, Seoul 136-701 (Korea, Republic of); Lee, Song Hee [Department of Life Science, Pohang University of Science and Technology, San 31, Hyoja Dong, Pohang, Kyungbuk 790-784 (Korea, Republic of); Jang, Sung Key [Department of Life Science, Pohang University of Science and Technology, San 31, Hyoja Dong, Pohang, Kyungbuk 790-784 (Korea, Republic of); Ahn, Byung-Yoon [School of Life Sciences and Biotechnology, Korea University, Seoul 136-701 (Korea, Republic of); Kim, Yoon Ki [School of Life Sciences and Biotechnology, Korea University, Seoul 136-701 (Korea, Republic of)]. E-mail: yk-kim@korea.ac.kr

2007-05-18

84

Predominant role by CaM kinase in NPY Y 1 receptor signaling: Involvement of CREB and Ambikaipakan 1 1 Abbreviations: ATF-1, activating transcription factor 1; AP1, activator protein-1; CaM kinase II, Calcium\\/calmodulin dependent protein kinase II; cAMP, cyclic 3?, 5? adenosine monophosphate; CRE, cyclic AMP response element; CREB, cyclic AMP response element binding protein; CREM, cyclic AMP response element binding modulator; D-PBS, Dulbecco’s phosphate-buffered saline (PBS); KN93, (2-[N-(2-hydroxyethyl)-N-(4-methoxybenzenesulfonyl)]amino-N-methyl-L-tyrosyl]-4-phenylpiperazine; MAPK, mitogen-activated protein kinase; NPY, neuropeptide Y; pCREB, phosphorylated cyclic AMP response element binding protein; PKA, protein kinase A; PMSF, phenylmethylsulfonyl fluoride; PYY, peptide YY; RLU, Relative light unit  

Microsoft Academic Search

The role of Ca2+\\/cAMP-dependent signal transduction and transcription factor CREB in mediating NPY- Y1 receptor function was investigated in SK-N-MC cells. The Y1 receptor agonist, [Leu31,Pro34]-NPY, inhibited forskolin-stimulated cAMP production which was insensitive to thapsigargin or the CaM kinase II inhibitor, KN-93. Although activation of the Y1 receptor leads to an increase in CREB phosphorylation, [Leu31,Pro34]-NPY inhibited CREB phosphorylation in

Sulaiman Sheriff; Asbah F. Qureshy; William T. Chance; John W Kasckow; Ambikaipakan Balasubramaniam

2002-01-01

85

Modulation by atrial natriuretic factor of receptor-mediated cyclic AMP-dependent responses in canine pulmonary artery during heart failure.  

PubMed Central

1. Pacing-induced congestive heart failure (CHF) in dogs is associated with increased plasma levels of atrial natriuretic factor (ANF) and inhibition of receptor-mediated cyclic AMP-dependent relaxation in isolated pulmonary arteries (PA). Since ANF is known to be negatively coupled to adenylate cyclase, we studied cyclic AMP-mediated relaxation to isoprenaline (Iso) and arachidonic acid (AA) in PA from control dogs (C), dogs with pacing-induced CHF (CHF) and dogs with bilateral atrial appendectomy and CHF (ATR APP+CHF). 2. In CHF, plasma ANF levels increased from a baseline of 80 +/- 8 pg ml-1 to 283 +/- 64 pg ml-1 (P < 0.05), but the ATR APP+CHF group failed to show this increase (67 +/- 7 pg ml-1 vs 94 +/- 15 pg ml-1, P = NS). Plasma ANF levels, however, did not influence myocardial dysfunction in CHF. 3. The relaxation of 49 +/- 5% to 1 microM Iso in C was reduced to 23 +/- 4% in CHF (P < 0.05), but relaxation of 49 +/- 12% was observed in the ATR APP+CHF group (P = NS vs C). Relaxation responses to 10 microM AA were as follows: 77 +/- 5% (C, n = 8), 27 +/- 8% (CHF, n = 10, P < 0.05 vs C), and 93 +/- 5% (ATR APP+CHF, n = 5). The presence of CHF, or the plasma ANF levels, did not affect responses to cyclic GMP-mediated relaxing agents in PA. 4. These data indicate that the myocardial performance in CHF is not influenced by plasma ANF levels. However, altered cyclic AMP-mediated relaxation in PA during CHF is, in part, modulated by circulating ANF levels.

Mathew, R.; Omar, H. A.; Fayngersh, R.; Shen, W.; Wang, J.; Gewitz, M. H.; Hintze, T. H.; Wolin, M. S.

1996-01-01

86

Activation of cyclic AMP-dependent kinase is required but may not be sufficient to mimic cyclic AMP-dependent DNA synthesis and thyroglobulin expression in dog thyroid cells.  

PubMed Central

Thyrotropin (TSH), via a cyclic AMP (cAMP)-dependent pathway, induces cytoplasmic retractions, proliferation, and differentiation expression in dog thyroid cells. The role of cAMP-dependent protein kinase (PKA) in the induction of these events was assessed by microinjection into living cells. Microinjection of the heat-stable inhibitor of PKA (PKI) inhibited the effects of TSH, demonstrating that activation of PKA was required in this process. Overexpression of the catalytic (C) subunit of PKA brought about by microinjection of the expression plasmid pC alpha ev or of purified C subunit itself was sufficient to mimic the cAMP-dependent cytoplasmic changes and thyroperoxidase mRNA expression but not to induce DNA synthesis and thyroglobulin (Tg) expression. The cAMP-dependent morphological effect was not observed when C subunit was coinjected with the regulatory subunit (RI or RII subunit) of PKA. To mimic the cAMP-induced PKA dissociation into free C and R subunits, the C subunit was coinjected with the regulation-deficient truncated RI subunit (RIdelta1-95) or with wild-type RI or native RII subunits, followed by incubation with TSH at a concentration too low to stimulate the cAMP-dependent events by itself. Although the cAMP-dependent morphology changes were still observed, neither DNA synthesis nor Tg expression was stimulated in these cells. Taken together, these data suggest that in addition to PKA activation, another cAMP-dependent mechanism could exist and play an important role in the transduction of the cAMP signal in thyroid cells.

Dremier, S; Pohl, V; Poteet-Smith, C; Roger, P P; Corbin, J; Doskeland, S O; Dumont, J E; Maenhaut, C

1997-01-01

87

Synergism between Calcium and Cyclic GMP in Cyclic AMP Response Element-Dependent Transcriptional Regulation Requires Cooperation between CREB and C/EBP-?  

PubMed Central

Calcium induces transcriptional activation of the fos promoter by activation of the cyclic AMP response element (CRE)-binding protein (CREB), and in some cells its effect is enhanced synergistically by cyclic GMP (cGMP) through an unknown mechanism. We observed calcium-cGMP synergism in neuronal and osteogenic cells which express type II cGMP-dependent protein kinase (G-kinase); the effect on the fos promoter was mediated by the CRE and proportional to G-kinase activity. Dominant negative transcription factors showed involvement of CREB- and C/EBP-related proteins but not of AP-1. Expression of C/EBP-? but not C/EBP-? or -? enhanced the effects of calcium and cGMP on a CRE-dependent reporter gene. The transactivation potential of full-length CREB fused to the DNA-binding domain of Gal4 was increased synergistically by calcium and cGMP, and overexpression of C/EBP-? enhanced the effect, while a dominant negative C/EBP inhibited it. With a mammalian two-hybrid system, coimmunoprecipitation experiments, and in vitro binding studies, we demonstrated that C/EBP-? and CREB interacted directly; this interaction involved the C terminus of C/EBP-? but occurred independently of CREB's leucine zipper domain. CREB Ser133 phosphorylation was stimulated by calcium but not by cGMP; in cGMP-treated cells, 32PO4 incorporation into C/EBP-? was decreased and C/EBP-?/CRE complexes were increased, suggesting regulation of C/EBP-? functions by G-kinase-dependent dephosphorylation. C/EBP-? and CREB associated with the fos promoter in intact cells, and the amount of promoter-associated C/EBP-? was increased by calcium and cGMP. We conclude that calcium and cGMP transcriptional synergism requires cooperation of CREB and C/EBP-?, with calcium and cGMP modulating the phosphorylation states of CREB and C/EBP-?, respectively.

Chen, Yongchang; Zhuang, Shunhui; Cassenaer, Stijn; Casteel, Darren E.; Gudi, Tanima; Boss, Gerry R.; Pilz, Renate B.

2003-01-01

88

Identification and function of exchange proteins activated directly by cyclic AMP (Epac) in mammalian spermatozoa.  

PubMed

The role of cAMP in spermatic functions was classically thought to be mediated exclusively through the activation of Protein Kinase A (PKA). However, it has recently been shown that cAMP also exerts its effects through a PKA-independent pathway activating a family of proteins known as Epac proteins. Therefore, many of the spermatic functions thought to be regulated by cAMP through the activation of PKA are again under study. We aimed to identify and to investigate the role of Epac proteins in spermatozoa using a specific permeable analog (8-Br-2'-O-Me-cAMP). Also, we aimed to study its relationship with E-cadherin, an adhesion protein involved in fertility. Our results demonstrate the presence and sub-cellular distribution of Epac 1 and Epac 2 in mammalian spermatozoa. Capacitation and the acrosome reaction induced a change in the localization of Epac proteins in sperm. Moreover, incubation with 8-Br-2'-O-Me-cAMP prompted an increase in Rap1 activation, in the scrambling of plasma membrane phospholipids (necessary for the capacitation process), the acrosome reaction, motility, and calcium mobilization, when spermatozoa were incubated in acrosome reaction conditions. Finally, the activation of Epac proteins induced a change in the distribution of E-cadherin. Therefore, the increase in the acrosome reaction, together with the increase in calcium (which is known to be essential for fertilization) and the Epac nteraction with E-cadherin, might indicate that Epac proteins have an important role in gamete recognition and fertilization. PMID:22662198

Miro-Moran, Alvaro; Jardin, Isaac; Ortega-Ferrusola, Cristina; Salido, Gines M; Peña, Fernando J; Tapia, Jose A; Aparicio, Ines M

2012-05-25

89

Montelukast inhibits neutrophil pro-inflammatory activity by a cyclic AMP-dependent mechanism  

PubMed Central

Background and purpose The objective of this study was to characterize the effects of the cysteinyl leukotriene receptor antagonist, montelukast (0.1–2 µmol·L?1), on Ca2+-dependent pro-inflammatory activities, cytosolic Ca2+ fluxes and intracellular cAMP in isolated human neutrophils activated with the chemoattractants, N-formyl-L-methionyl-L-leucyl-L-phenylalanine (1 µmol·L?1) and platelet-activating factor (200 nmol·L?1). Experimental approach Generation of reactive oxygen species was measured by lucigenin- and luminol-enhanced chemiluminescence, elastase release by a colourimetric assay, leukotriene B4 and cAMP by competitive binding ELISA procedures, and Ca2+ fluxes by fura-2/AM-based spectrofluorimetric and radiometric (45Ca2+) procedures. Key results Pre-incubation of neutrophils with montelukast resulted in dose-related inhibition of the generation of reactive oxygen species and leukotriene B4 by chemoattractant-activated neutrophils, as well as release of elastase, all of which were maximal at 2 µmol·L?1 (mean percentages of the control values of 30 ± 1, 12 ± 3 and 21 ± 3 respectively; P < 0.05). From a mechanistic perspective, treatment of chemoattractant-activated neutrophils with montelukast resulted in significant reductions in both post-peak cytosolic Ca2+ concentrations and store-operated Ca2+ influx. These montelukast-mediated alterations in Ca2+ handling by the cells were associated with a significant elevation in basal cAMP levels, which resulted from inhibition of cyclic nucleotide phosphodiesterases. Conclusions and implications Montelukast, primarily a cysteinyl leukotriene (CysLT1) receptor antagonist, exhibited previously undocumented, secondary, neutrophil-directed anti-inflammatory properties, which appeared to be cAMP-dependent.

Anderson, Ronald; Theron, Annette J; Gravett, Cornelia M; Steel, Helen C; Tintinger, Gregory R; Feldman, Charles

2009-01-01

90

Adenylyl cyclase 6 mediates the action of cyclic AMP-dependent secretagogues in mouse pancreatic exocrine cells via protein kinase A pathway activation.  

PubMed

Both secretin and vasoactive intestinal polypeptide (VIP) receptors are responsible for the activation of adenylyl cyclases (ACs), which increase intracellular cyclic AMP (cAMP) levels in the exocrine pancreas. There are nine membrane-associated isoforms, each with its own pattern of expression and regulation. In this study we sought to establish which AC isoforms play a regulatory role in pancreatic exocrine cells. Using RT-PCR, AC3, AC4, AC6, AC7 and AC9 were found to be expressed in the pancreas. AC3, AC4, AC6 and AC9 were expressed in both pancreatic acini and ducts, whereas AC7 was expressed only in pancreatic ducts. Based on known regulation by intracellular signals, selective inhibitors and stimulators were used to suggest which isoforms play an important role in the induction of cAMP formation. AC6 appeared to be an important isoform because protein kinase A (PKA), PKC and calcium all inhibited VIP-induced cAMP formation, whereas calcineurin or calmodulin did not modify the response to VIP. Mice with genetically deleted AC6 were studied and showed reduced cAMP formation and PKA activation in both isolated pancreatic acini and duct fragments. The absence of AC6 reduced cAMP-dependent secretagogue-stimulated amylase secretion, and abolished fluid secretion in both in vivo and isolated duct fragments. In conclusion, several AC isoforms are expressed in pancreatic acini and ducts. AC6 mediates a significant part of pancreatic amylase and fluid secretion in response to secretin, VIP and forskolin through cAMP/PKA pathway activation. PMID:23753526

Sabbatini, Maria E; D'Alecy, Louis; Lentz, Stephen I; Tang, Tong; Williams, John A

2013-06-10

91

Mlc is a transcriptional activator with a key role in integrating cyclic AMP receptor protein and integration host factor regulation of leukotoxin RNA synthesis in Aggregatibacter actinomycetemcomitans.  

PubMed

Aggregatibacter actinomycetemcomitans, a periodontal pathogen, synthesizes leukotoxin (LtxA), a protein that helps the bacterium evade the host immune response. Transcription of the ltxA operon is induced during anaerobic growth. The cyclic AMP (cAMP) receptor protein (CRP) indirectly increases ltxA expression, but the intermediary regulator is unknown. Integration host factor (IHF) binds to and represses the leukotoxin promoter, but neither CRP nor IHF is responsible for the anaerobic induction of ltxA RNA synthesis. Thus, we have undertaken studies to identify other regulators of leukotoxin transcription and to demonstrate how these proteins work together to modulate leukotoxin synthesis. First, analyses of ltxA RNA expression from defined leukotoxin promoter mutations in the chromosome identify positions -69 to -35 as the key control region and indicate that an activator protein modulates leukotoxin transcription. We show that Mlc, which is a repressor in Escherichia coli, functions as a direct transcriptional activator in A. actinomycetemcomitans; an mlc deletion mutant reduces leukotoxin RNA synthesis, and recombinant Mlc protein binds specifically at the -68 to -40 region of the leukotoxin promoter. Furthermore, we show that CRP activates ltxA expression indirectly by increasing the levels of Mlc. Analyses of ?mlc, ?ihf, and ?ihf ?mlc strains demonstrate that Mlc can increase RNA polymerase (RNAP) activity directly and that IHF represses ltxA RNA synthesis mainly by blocking Mlc binding. Finally, a ?ihf ?mlc mutant still induces ltxA during anaerobic growth, indicating that there are additional factors involved in leukotoxin transcriptional regulation. A model for the coordinated regulation of leukotoxin transcription is presented. PMID:23475968

Childress, Catherine; Feuerbacher, Leigh A; Phillips, Linda; Burgum, Alex; Kolodrubetz, David

2013-03-08

92

Effects of porcine relaxin on contraction, membrane response and cyclic AMP content in rat myometrium in comparison with the effects of isoprenaline and forskolin.  

PubMed Central

1. The longitudinal muscle from the uterus of oestrogen-treated rats was quiescent in Mg-free Krebs solution. Electrical stimulation generated phasic contraction, which was depressed to 35% and 18% by 50 mu and 150 mu porcine relaxin, respectively. 2. The phasic contractions were more strongly depressed to 26% by 50 mu relaxin in solution containing 0.6 mM Mg, and the depression lasted for more than 4 h after the removal of relaxin. During the persisting depression, raising the external Ca to 7.5 mM did not restore the contraction, but the contraction was restored by removal of Mg. 3. The depression of the phasic contraction by relaxin, examined in Mg-free solution, was enhanced and reduced by pretreatment of the tissue with 0.6 mM Mg and 0.6 mM Mn, respectively, for about 15 min. In contrast, the depression of contraction by isoprenaline or forskolin was enhanced by pretreatment with either Mg or Mn. 4. The cellular content of cyclic AMP was measured in Krebs solution containing 0.6 mM Mg. The values were 1.24 (pmol mg-1 protein) in control solution, and 2.31 and 1.56 when the tissues were treated with 150 mu relaxin and 10(-9) M isoprenaline, respectively. 5. The cyclic AMP production in response to 10(-7) M forskolin measured in Mg-free solution was enhanced when the tissue was pretreated with either 0.6 mM Mg or Mn for 15 min. The cyclic AMP production in response to 100 mu relaxin was increased when the tissue was pretreated with 0.6 mM Mg, and was unchanged by pretreatment with Mn. The cyclic AMP production in response to 10(-9) M isoprenaline was unchanged by pretreatment with the divalent cations. 6. The membrane potential of the muscle was -60.8 mV in Krebs solution containing 0.3 mM Mg, and electrical stimulation induced an action potential which consisted of spike and plateau components. Application of 150 mu relaxin reduced the duration of the plateau; the contractions were progressively depressed. The resting membrane potential and membrane resistance were unchanged by application of 150 mu relaxin. The membrane was hyperpolarized by 2.8 mV, accompanied by a decrease in membrane resistance, when 10(-9) M isoprenaline was applied. 7. Although there were several differences between the effects of relaxin and isoprenaline, it is probable that some process, which is cyclic AMP-dependent, accelerated by Mg and depressed by Mn, is involved in the depressant action of relaxin on contraction.

Osa, T.; Inoue, H.; Okabe, K.

1991-01-01

93

GABA(B) receptor activation protects GABA(A) receptor from cyclic AMP-dependent down-regulation in rat cerebellar granule cells.  

PubMed

Interaction between GABAA and GABA(B) receptors was studied in rat cerebellar granule cells in culture, by the whole-cell patch-clamp approach. Our data show that the GABA(B) agonist (-)baclofen is not able, per se, to significantly change the muscimol-activated chloride current. However, (-)baclofen dose-dependently prevents the reduction of GABA(A) receptor function by forskolin, an activator of adenylate cyclase. The effect of baclofen is mediated by a pertussis toxin-sensitive G protein. In fact, in cells treated with pertussis toxin, baclofen and forskolin, the toxin is able to block baclofen action, allowing forskolin to act fully. The protective effect by GABA(B) receptor activation under these circumstances is most probably related to the prevention of cyclic AMP increases after forskolin treatment. In fact, in these neurons cyclic AMP and protein kinase A activation result in a down-regulation of GABA(A) receptor function. On the whole, the data indicate the presence of complex modulation of GABA(A) receptors by GABA(B) receptor types in cerebellum granule cells. PMID:10473272

Barilà, B; Cupello, A; Robello, M

1999-01-01

94

21 CFR 862.1230 - Cyclic AMP test system.  

Code of Federal Regulations, 2010 CFR

... Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure the level of adenosine 3â², 5â²-monophosphate (cyclic AMP) in plasma, urine, and other body fluids. Cyclic AMP measurements are...

2009-04-01

95

21 CFR 862.1230 - Cyclic AMP test system.  

Code of Federal Regulations, 2010 CFR

... Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure the level of adenosine 3â², 5â²-monophosphate (cyclic AMP) in plasma, urine, and other body fluids. Cyclic AMP measurements are...

2010-04-01

96

Cyclic AMP-Rap1A signaling activates RhoA to induce ?2c-adrenoceptor translocation to the cell surface of microvascular smooth muscle cells  

PubMed Central

Intracellular signaling by the second messenger cyclic AMP (cAMP) activates the Ras-related small GTPase Rap1 through the guanine exchange factor Epac. This activation leads to effector protein interactions, activation, and biological responses in the vasculature, including vasorelaxation. In vascular smooth muscle cells derived from human dermal arterioles (microVSM), Rap1 selectively regulates expression of G protein-coupled ?2C-adrenoceptors (?2C-ARs) through JNK-c-jun nuclear signaling. The ?2C-ARs are generally retained in the trans-Golgi compartment and mobilize to the cell surface and elicit vasoconstriction in response to cellular stress. The present study used human microVSM to examine the role of Rap1 in receptor localization. Complementary approaches included murine microVSM derived from tail arteries of C57BL6 mice that express functional ?2C-ARs and mice deficient in Rap1A (Rap1A-null). In human microVSM, increasing intracellular cAMP by direct activation of adenylyl cyclase by forskolin (10 ?M) or selectively activating Epac-Rap signaling by the cAMP analog 8-pCPT-2?-O-Me-cAMP (100 ?M) activated RhoA, increased ?2C-AR expression, and reorganized the actin cytoskeleton, increasing F-actin. The ?2C-ARs mobilized from the perinuclear region to intracellular filamentous structures and to the plasma membrane. Similar results were obtained in murine wild-type microVSM, coupling Rap1-Rho-actin dynamics to receptor relocalization. This signaling was impaired in Rap1A-null murine microVSM and was rescued by delivery of constitutively active (CA) mutant of Rap1A. When tested in heterologous HEK293 cells, Rap1A-CA or Rho-kinase (ROCK-CA) caused translocation of functional ?2C-ARs to the cell surface (?4- to 6-fold increase, respectively). Together, these studies support vascular bed-specific physiological role of Rap1 and suggest a role in vasoconstriction in microVSM.

Jeyaraj, Selvi C.; Unger, Nicholas T.; Eid, Ali H.; Mitra, Srabani; Paul El-Dahdah, N.; Quilliam, Lawrence A.; Flavahan, Nicholas A.

2012-01-01

97

Ethanol-induced loss of brain cyclic AMP binding proteins: correlation with growth suppression  

SciTech Connect

Brain hypoplasia secondary to maternal ethanol consumption is a common fetal defect observed in all models of fetal alcohol syndrome. The molecular mechanism by which ethanol inhibits growth is unknown but has been hypothesized to involve ethanol-induced changes in the activity of cyclic-AMP stimulated protein kinase. Acute and chronic alcohol exposure elevate cyclic AMP level in many tissues, including brain. This increase in cyclic AMP should increase the phosphorylating activity of kinase by increasing the amount of dissociated (active) kinase catalytic subunit. In 7-day embryonic chick brains, ethanol-induced growth suppression was correlated with increased brain cyclic AMP content but neither basal nor cyclic AMP stimulated kinase catalytic activity was increased. However, the levels of cyclic AMP binding protein (kinase regulatory subunit) were significantly lowered by ethanol exposure. Measured as either /sup 3/H cyclic AMP binding or as 8-azido cyclic AM/sup 32/P labeling, ethanol-exposed brains had significantly less cyclic AMP binding activity (51 +/- 14 versus 29 +/- 10 units/..mu..g protein for 8-azido cyclic AMP binding). These findings suggest that ethanol's effect on kinase activity may involve more than ethanol-induced activation of adenylate cyclase.

Pennington, S.; Kalmus, G.

1987-05-01

98

TSH-induced cyclic AMP production in an ovine thyroid cell line: OVNIS 5H.  

PubMed

The TSH-induced cyclic AMP response was studied using a 3-year-old ovine thyroid cell line TSH-independent for growth: OVNIS 5H. The kinetics of cyclic AMP production was followed both in cell layers and in cell culture media, with or without phosphodiesterase inhibitor. It is noteworthy that following the first wave in cyclic AMP obtained within minutes, we observed later a sustained exponential increase in cyclic AMP during the 5 days following TSH stimulation. A bioassay of TSH was derived allowing measurement of 1 microU/ml TSH from a crude bTSH preparation. PMID:3000830

Fayet, G; Aouani, A; Hovsépian, S

1986-01-01

99

Basal phosphorylation of cyclic AMP-regulated phosphoproteins in intact S49 mouse lymphoma cells.  

PubMed Central

Protein phosphorylation in intact S49 mouse lymphoma cells was studied by using high-resolution two-dimensional gel electrophoresis of proteins labelled with [35S]methionine or [32P]Pi. In wild-type cells substrates for cyclic AMP-stimulatable phosphorylation exhibited high basal phosphorylation; in mutant cells deficient in activities of either cyclic AMP-dependent protein kinase or adenylate cyclase, basal phosphorylation of most of these substrates was negligible. Analysis of tryptic phosphopeptides from proteins labelled with [32P]Pi in wild-type cells suggested that identical sites were phosphorylated under conditions of both basal and hormonally elevated concentrations of cyclic AMP. These results argue that most basal phosphorylation is a consequence of partial activation of cyclic AMP-dependent protein kinase and that this activation is attributable to basal concentrations of cyclic AMP. For the intermediate filament protein vimentin, basal phosphorylation was largely at a site distinct from that stimulated by increased cyclic AMP, and basal phosphorylation was not markedly different in mutant and wild-type cells. Vimentin phosphorylated at both sites was not observed. Cyclic AMP treatment resulted in enhanced phosphorylation at the cyclic AMP-specific site and decreased phosphorylation at the cyclic AMP-independent site. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5.

Steinberg, R A; Kiss, Z

1985-01-01

100

A reassessment of the modulatory role of cyclic AMP in catecholamine secretion by chromaffin cells.  

PubMed Central

1. The role of adenosine 3':5'-cyclic monophosphate (cyclic AMP) in the regulation of catecholamine (CA) secretion in chromaffin cells remains equivocal from previous studies. 2. In the present study the effect of this cyclic nucleotide on basal CA secretion, as well as on intracellular calcium and membrane potential has been examined. 3. Forskolin and the permeable cyclic AMP analogue, 8-(4-chlorphenylthio)-adenosine-3'-5' monophosphate cyclic (pClpcAMP), increased basal CA secretion in a dose-dependent manner. The EC50s were 0.43 +/- 0.10 microM for forskolin and 39 +/- 9 microM for pClpcAMP. Other agonists with adenylate cyclase activity such as stimulants of adenosine receptors, beta-adrenoceptors, GABAB receptors and intestinal vasoactive peptide (VIP), also increased basal CA secretion in a highly significant manner. However, when they were added together with forskolin, CA secretion was not affected although an additive increase in cyclic AMP levels was produced. 4. Statistical analysis of the correlation between cyclic AMP levels and CA secretion evoked by these cyclic AMP increasing compounds showed that a significant direct correlation between both parameters existed only when low levels of cyclic AMP were produced by secretagogue stimulation. When the increase in intracellular cyclic AMP concentrations exceeded approximately 8 times the basal cyclic AMP levels the correlation was not significant. These results indicate a dual dose-dependent effect of cyclic AMP on basal CA secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Parramon, M; Gonzalez, M P; Oset-Gasque, M J

1995-01-01

101

Role of Actin Cytoskeletal Dynamics in Activation of the Cyclic AMP Pathway and HWP1 Gene Expression in Candida albicans? †  

PubMed Central

Changes in gene expression during reversible bud-hypha transitions of the opportunistic fungal pathogen Candida albicans permit adaptation to environmental conditions that are critical for proliferation in host tissues. Our previous work has shown that the hypha-specific adhesin gene HWP1 is up-regulated by the cyclic AMP (cAMP) signaling pathway. However, little is known about the potential influences of determinants of cell morphology on HWP1 gene expression. We found that blocking hypha formation with cytochalasin A, which destabilizes actin filaments, and with latrunculin A, which sequesters actin monomers, led to a loss of HWP1 gene expression. In contrast, high levels of HWP1 gene expression were observed when the F-actin stabilizer jasplakinolide was used to block hypha formation, suggesting that HWP1 expression could be regulated by actin structures. Mutants defective in formin-mediated nucleation of F-actin were reduced in HWP1 gene expression, providing genetic support for the importance of actin structures. Kinetic experiments with wild-type and actin-deficient cells revealed two distinct phases of HWP1 gene expression, with a slow, actin-independent phase preceding a fast, actin-dependent phase. Low levels of HWP1 gene expression that appeared to be independent of stabilized actin and cAMP signaling were detected using indirect immunofluorescence. A connection between actin structures and the cAMP signaling pathway was shown using hyper- and hypomorphic cAMP mutants, providing a possible mechanism for up-regulation of HWP1 gene expression by stabilized actin. The results reveal a new role for F-actin as a regulatory agent of hypha-specific gene expression at the bud-hypha transition.

Wolyniak, Michael J.; Sundstrom, Paula

2007-01-01

102

Ephedrine induced thioredoxin-1 expression through ?-adrenergic receptor/cyclic AMP/protein kinase A/dopamine- and cyclic AMP-regulated phosphoprotein signaling pathway.  

PubMed

Ephedrine (Eph) is one of alkaloids that has been isolated from the ancient herb ephedra (ma huang) and is used as the treatment of asthma, hypotension and fatigue. However, its molecular mechanism remains unknown. Thioredoxin-1 (Trx-1) is a redox regulating protein, which has various biological activities, including regulating transcription factor DNA binding activity and neuroprotection. In this study, we found that Eph induced Trx-1 expression, which was inhibited by propranolol (?-adrenergic receptor inhibitor), but not by phenoxybenzamine (?-adrenergic receptor inhibitor) in rat pheochromocytoma PC12 cells. Moreover, the increase of Trx-1 expression was inhibited by SQ22536 (adenylyl cyclase inhibitor) and H-89 (protein kinase A inhibitor). Interestingly, the effect of Eph on dopamine- and cyclic AMP-regulated phosphoprotein (DARPP-32) was similar to Trx-1. Thus, the relationship between Trx-1 and DARPP-32 was further studied. The DARPP-32 siRNA significantly reduced Trx-1 expression, but Trx-1 siRNA did not exchange DARPP-32. These results suggested that Eph induced the Trx-1 expression through ?-adrenergic receptor/cyclic AMP/PKA/DARPP-32 signaling pathway. Furthermore, Eph induced PKA-mediated cyclic AMP response element-binding protein (CREB) phosphorylation. Down-regulation of DARPP-32 expression decreased phosphorylated CREB. In addition, Eph had a significant effect on the viability of the rat pheochromocytoma PC12 cells through ?-adrenergic receptors. Trx-1 may play an important role in the actions of Eph. PMID:23416460

Jia, Jin-Jing; Zeng, Xian-Si; Li, Ye; Ma, Sha; Bai, Jie

2013-02-14

103

Gotu Kola (Centella Asiatica) extract enhances phosphorylation of cyclic AMP response element binding protein in neuroblastoma cells expressing amyloid beta peptide.  

PubMed

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that shows cognitive deficits and memory impairment. Extract from the leaves of Gotu Kola (Centella Asiatica) have been used as an alternative medicine for memory improvement in Indian Ayurvedic system of medicine for a long time. Although several studies have revealed its effect in ameliorating the cognitive impairment in rat models of AD and stimulating property on neuronal dendrites of hippocampal region, the molecular mechanism of Gotu Kola on neuroprotection still remains to be elucidated. In this study, we report that phosphorylation of cyclic AMP response element binding protein (CREB) is enhanced in both a neuroblastoma cell line expressing amyloid beta 1-42 (Abeta) and in rat embryonic cortical primary cell culture. In addition, the contribution of two major single components to the enhanced CREB phosphorylatioin was examined. Furthermore, inhibitors were applied in this study revealing that ERK/RSK signaling pathway might mediate this effect of Gotu Kola extract. Taken together, we provide a possible molecular mechanism for memory enhancing property of Gotu Kola extract for the first time. PMID:18431001

Xu, Yanan; Cao, Zhiming; Khan, Ikhlas; Luo, Yuan

2008-04-01

104

CYCLIC AMP AND PSORIASIS  

Microsoft Academic Search

Evidence that an adenyl cyclase system is present in all mammalian epidermis is reviewed. This adenyl cyclase is stimulated by at least two separate types of chemicals: catecholamines, which act at a ?-adrenergic receptor site, and prostaglandins oft he E series, which act at a separate site. In the psoriatic lesion, the response to these stimulators. especially to the catecholamines,

Kenneth M. Halprin; Kenji Adachi; Kunihiko Yoshikawa; Victor Levine; Mei Mei Mui; S. L. Hsia

1975-01-01

105

Differential regulation of prohormone convertase 1/3, prohormone convertase 2 and phosphorylated cyclic-AMP-response element binding protein by short-term and long-term morphine treatment: implications for understanding the "switch" to opiate addiction.  

PubMed

Drug addiction is a state of altered brain reward and self-regulation mediated by both neurotransmitter and hormonal systems. Although an organism's internal system attempts to maintain homeostasis when challenged by exogenous opiates and other drugs of abuse, it eventually fails, resulting in the transition from drug use to drug abuse. We propose that the attempted maintenance of hormonal homeostasis is achieved, in part, through alterations in levels of processing enzymes that control the ratio of active hormone to pro-hormone. Two pro-hormone convertases, PC1/3 and PC2 are believed to be responsible for the activation of many neurohormones and expression of these enzymes is dependent on the presence of a cyclic-AMP response element (CRE) in their promoters. Therefore, we studied the effects of short-term (24-h) and long-term (7-day) morphine treatment on the expression of hypothalamic PC1/3 and PC2 and levels of phosphorylated cyclic-AMP-response element binding protein (P-CREB). While short-term morphine exposure down-regulated, long-term morphine exposure up-regulated P-CREB, PC1/3 and PC2 protein levels in the rat hypothalamus as determined by Western blot analysis. Quantitative immunofluorescence studies confirmed these regulatory actions of morphine in the paraventricular and dorsomedial nucleus of the hypothalamus. Specific radioimmunoassays demonstrated that the increase in PC1/3 and PC2 levels following long-term morphine led to increased TRH biosynthesis as evidence by increased TRH/5.4 kDa C-terminal proTRH-derived peptide ratios in the median eminence. Promoter activity experiments in rat somatomammotrope GH3 cells containing the mu-opioid receptor demonstrated that the CRE(s) in the promoter of PC1/3 and PC2 is required for morphine-induced regulation of PC1/3 and PC2. Our data suggest that the regulation of the prohormone processing system by morphine may lead to alterations in the levels of multiple bioactive hormones and may be a compensatory mechanism whereby the organism tries to restore its homeostatic hormonal milieu. The down-regulation of PC1/3, PC2 and P-CREB by short-term morphine and up-regulation by long-term morphine treatment may be a signal mediating the switch from drug use to drug abuse. PMID:18771713

Espinosa, V Paez; Liu, Y; Ferrini, M; Anghel, A; Nie, Y; Tripathi, P V; Porche, R; Jansen, E; Stuart, R C; Nillni, E A; Lutfy, K; Friedman, T C

2008-08-09

106

Subcellular Localization and Biological Actions of Activated RSK1 Are Determined by Its Interactions with Subunits of Cyclic AMP-Dependent Protein Kinase†  

PubMed Central

Cyclic AMP (cAMP)-dependent protein kinase (PKA) and ribosomal S6 kinase 1 (RSK1) share several cellular proteins as substrates. However, to date no other similarities between the two kinases or interactions between them have been reported. Here, we describe novel interactions between subunits of PKA and RSK1 that are dependent upon the activation state of RSK1 and determine its subcellular distribution and biological actions. Inactive RSK1 interacts with the type I regulatory subunit (RI) of PKA. Conversely, active RSK1 interacts with the catalytic subunit of PKA (PKAc). Binding of RSK1 to RI decreases the interactions between RI and PKAc, while the binding of active RSK1 to PKAc increases interactions between PKAc and RI and decreases the ability of cAMP to stimulate PKA. The RSK1/PKA subunit interactions ensure the colocalization of RSK1 with A-kinase PKA anchoring proteins (AKAPs). Disruption of the interactions between PKA and AKAPs decreases the nuclear accumulation of active RSK1 and, thus, increases its cytosolic content. This subcellular redistribution of active RSK1 is manifested by increased phosphorylation of its cytosolic substrates tuberous sclerosis complex 2 and BAD by epidermal growth factor along with decreased cellular apoptosis.

Chaturvedi, Deepti; Poppleton, Helen M.; Stringfield, Teresa; Barbier, Ann; Patel, Tarun B.

2006-01-01

107

Age-related changes of cyclic AMP phosphodiesterase activity in rat brain regions and a new phosphodiesterase inhibitor--nootropic agent adafenoxate.  

PubMed

1. The low- and high-KM cyclic AMP phosphodiesterase (cAMP PDE) activity in cerebral cortex, striatum, hypothalamus and hippocampus of young (4-5-month-old) and aged (22-month-old) rats has been studied. 2. A significant rise in the high-KM cAMP PDE activity in the cerebral cortex, hypothalamus and hippocampus in aged rats has been found. 3. The activity of the low-KM cAMP PDE does not change during senescence in all the brain structures studied. 4. In a series of increased concentrations (from 5 x 10(-4) to 1 x 10(-5) M) adafenoxate inhibits low- and high-KM cAMP PDE in most of the brain structures studied in both age groups. 5. The present results provide evidence for realization of the CNS effects of adafenoxate through inhibition of cAMP PDE activity and regulation of the intracellular level of cAMP. PMID:1662175

Stancheva, S L; Alova, L G

1991-01-01

108

Changes in cyclic AMP content of rat gastric mucosa induced by ulcerogenic stimuli--in relation to the antiulcer activity of irsogladine maleate.  

PubMed

Changes in the cyclic AMP (cAMP) content of the gastric mucosa induced by ulcerogenic stimuli were investigated in rats. Ligation of the pylorus for 5 hr produced no glandular mucosal lesion, but increased the cAMP content in the fundus and antrum. Aspirin produced glandular mucosal lesions in the pylorus-ligated rats and caused an increase of the cAMP content in the fundus and a decrease in the antrum. Irsogladine maleate (IM), an antiulcer agent, inhibited both the changes in the cAMP content and the mucosal damage induced by aspirin. IM increased the cAMP content in both regions, especially the antrum, in normal rats. Dibutyryl cAMP (dbcAMP) given orally prevented the gastric mucosal lesions induced by aspirin without affecting gastric secretion. These results suggest that 1) the changes in the cAMP content of the fundus and antrum induced by aspirin may be associated with the formation of glandular mucosal damage, 2) the antiulcer activity of IM may be related to an increase of the cAMP content in mucous cells, and 3) dbcAMP given orally may penetrate into the surface mucous cells and activate defensive functions. Thus, cAMP in the mucous cells may protect the gastric mucosa. PMID:1653374

Ueda, F; Watanabe, M; Hirata, Y; Kyoi, T; Kimura, K

1991-04-01

109

Multiple Control of Flagellum Biosynthesis in Escherichia coli: Role of H-NS Protein and the Cyclic AMP-Catabolite Activator Protein Complex in Transcription of the flhDC Master Operon  

Microsoft Academic Search

Little is known about the molecular mechanism by which histone-like nucleoid-structuring (H-NS) protein and cyclic AMP-catabolite activator protein (CAP) complex control bacterial motility. In the present paper, we show that crp and hns mutants are nonmotile due to a complete lack of flagellin accumulation. This results from a reduced expression in vivo of fliA and fliC, which encode the specific

O. SOUTOURINA; A. KOLB; E. KRIN; C. LAURENT-WINTER; S. RIMSKY; A. DANCHIN; P. BERTIN

1999-01-01

110

Bronchodilator drug efficacy via cyclic AMP  

Microsoft Academic Search

Cyclic adenosine 3', 5'-monophosphosphate (cyclic AMP) as measured by radioimmunoassay is found in diced rat lung in an amount approximating one picomole per milligram of wet weight lung tissue. Incubation of rat lung with adrenaline, a beta adrenergic agent, produced a rapid increase in cyclic AMP, 100% increase at 15 seconds and 340% at 2 minutes. Isoprenaline was more stimulatory

P E Duncan; J P Griffin; S S Solomon

1975-01-01

111

Paradoxical stimulation of cyclooxygenase-2 expression by glucocorticoids via a cyclic AMP response element in human amnion fibroblasts.  

PubMed

Human amnion fibroblasts produce abundant prostaglandins toward the end of gestation, which is one of the major events leading to parturition. In marked contrast to its well-described antiinflammatory effect, glucocorticoids have been shown to up-regulate cyclooxygenase-2 (COX-2) expression in human amnion fibroblasts. The mechanisms underlying this paradoxical induction of COX-2 by glucocorticoids have not been resolved. Using cultured human amnion fibroblasts, we found that the induction of COX-2 mRNA expression by cortisol was a glucocorticoid receptor (GR)-dependent process requiring ongoing transcription. Upon transfection of a COX-2 promoter-driven reporter gene into the amnion fibroblasts, cortisol stimulated the COX-2 promoter activity. This was abolished by mutagenesis of a cAMP response element (CRE) at -53 to approximately -59bp as well as by cotransfection of a plasmid expressing dominant-negative CRE-binding protein (CREB). The phosphorylation level of CREB-1 was significantly increased by cortisol treatment of the amnion fibroblasts, whereas the effect was attenuated either by the protein kinase A inhibitor H89 or the p38 -MAPK inhibitor SB203580. The induction of the COX-2 promoter activity and the phosphorylation of CREB-1 were also blocked by the GR antagonist RU486. Chromatin immunoprecipitation (ChIP) assay revealed that the binding of CREB-1 to the CRE of the COX-2 promoter was increased by cortisol treatment of the amnion fibroblasts. In conclusion, cortisol, via binding to GR, stimulated COX-2 expression by increasing phosphorylated CREB-1 binding to the CRE of the COX-2 gene. Cortisol may phosphorylate CREB-1 by activating either protein kinase A or p38-MAPK in the amnion fibroblasts. PMID:19797430

Zhu, X O; Yang, Z; Guo, C M; Ni, X T; Li, J N; Ge, Y C; Myatt, L; Sun, K

2009-10-01

112

Effects of osmolality and oxygen availability on soluble cyclic AMP-dependent protein kinase activity of rat renal inner medulla.  

PubMed Central

The renal inner medulla is ordinarily exposed to osmolalities that are much higher and to O2 tensions that are lower than those in other tissues. The effects of media osmolality and O2 availability on basal and arginine vasopressin(AVP)-responsive soluble cyclic (c)AMP-dependent protein kinase activity were examined in slices of rat inner medulla. Increasing total media osmolality from 305 to 750 or 1,650 mosM by addition of urea plas NaCl to standard Krebs-Ringer bicarbonate buffer significantly reduced basal cAMP content and protein kinase activity ratios. This occurred in the presence or absence of O2. Incubation of slices in high osmolality buffer also blunted increases in inner medullary slice cAMP and protein kinase activity ratios induced by O2. These changes reflected predominantly an action of the urea rather than the NaCl content of high osmolality buffers. In contrast to effects on basal activity, high media osmolality significantly enhanced activation of inner medullary protein kinase by AVP. Conversely, increases in media O2 content suppressed AVP stimulation of enzyme activity. This inhibitory effect of O2 was best expressed at low osmolality. Naproxen and ibuprofen, inhibitors of prostaglandin biosynthesis, reduced basal kinase activity ratios and increased AVP responsiveness in the presence, but not in the absence, of O2. Exogenous prostaglandins (PG) modestly increased (PGE2 and PGE1) or did not change (PGF2alpha) cAMP and protein kinase activity ratios in O2-deprived inner medullary slices. Protein kinase activation by PGE2 was not observed in oxygenated inner medulla with high basal activity ratios. The stimulatory effects of PGE2 and PGE1 on protein kinase activity observed in O2-deprived slices were additive with those of submaximal or maximal AVP. PGE2, PGE1, and PGF2alpha all failed to suppress AVP activation of protein kinase. Thus, enhanced endogenous PGE production may contribute to the higher basal protein kinase activity ratios induced by O2. However, the results do not support a role for PGE2, PGE1, or PGF2alpha in O2-mediated inhibition of AVP responsiveness. The present data indicate that both solute content and O2 availability can alter the expression of AVP action on cAMP-dependent protein kinase activity in inner medulla. AVP activation of protein kinase is best expressed when osmolality is high and O2 availability is low, conditions that pertain in inner medulla during hydropenia.

DeRubertis, F R; Craven, P A

1978-01-01

113

cap alpha. /sub 2/-Adrenergic receptor-mediated sensitization of forskolin-stimulated cyclic AMP production  

SciTech Connect

Preincubation of HT29 human colonic adenocarcinoma cells with ..cap alpha../sub 2/-adrenergic agonists resulted in a 10- to 20-fold increase in forskolin-stimulated cyclic AMP production as compared to cells preincubated without agonist. Similar results were obtained using either a (/sup 3/H)adenine prelabeling assay or a cyclic AMP radioimmunoassay to measure cyclic AMP levels. This phenomenon, which is termed sensitization, is ..cap alpha../sub 2/-adrenergic receptor-mediated and rapid in onset and reversal. Yohimbine, an ..cap alpha../sub 2/-adrenergic receptor-selective antagonist, blocked norepinephrine-induced sensitization, whereas prazosin (..cap alpha../sub 1/-adrenergic) and sotalol (..beta..-adrenergic) did not. The time for half-maximal sensitization was 5 min and the half-time for reversal was 10 min. Only a 2-fold sensitization of cyclic AMP production stimulated by vasoactive intestinal peptide was observed, indicating that sensitization is relatively selective for forskolin. Sensitization reflects an increased production of cyclic AMP and not a decreased degradation of cyclic AMP, since incubation with a phosphodiesterase inhibitor and forskolin did not mimic sensitization. Increasing the levels of cyclic AMP during the preincubation had no effect on sensitization, indicating that sensitization is not caused by decreased cyclic AMP levels during the preincubation. This rapid and dramatic sensitization of forskolin-stimulated cyclic AMP production is a previously unreported effect that can be added to the growing list of ..cap alpha../sub 2/-adrenergic responses that are not mediated by a decrease in cyclic AMP.

Jones, S.B.; Toews, M.L.; Turner, J.T.; Bylund, D.B.

1987-03-01

114

The plasma cyclic-AMP response to noise in humans and rats-short-term exposure to various noise levels  

NASA Astrophysics Data System (ADS)

Rats were exposed to short-term noise which was found to activate the hypothalamohypophyseal-adrenal system and result in a decrease of adrenal ascorbic acid (AAA) and an increase of serum corticosterone (SCS). The threshold limit value lay between 60 and 70 dB(A). To characterize better the effect of noise on the human hypothalamo-hypophyseal-adrenal system, a large group of subjects was exposed to short-term noise at 85 dB(A) and higher, and tested for levels of adrenocortical steroid (cortisol) and anterior pituitary hormones such as ACTH, growth hormone (GH) and prolactin (PRL). Results in humans showed hyperfunction of the hypothalamo-pituitary system. However, as the responses in rats and humans differed, a further experiment was performed using C-AMP, a second messenger mediating many of the effects of a variety of hormones. Plasma C-AMP in humans and rats increased significantly after exposure to noise greater than 70 dB(A). We suggest that plasma C-AMP could be useful as a sensitive index for noise-related stress in the daily living environment of humans and rats.

Iwamoto, M.; Dodo, H.; Ishii, F.; Yoneda, J.; Yamazaki, S.; Goto, H.

1988-12-01

115

Activation of Exchange Protein Activated by Cyclic-AMP Enhances Long-Lasting Synaptic Potentiation in the Hippocampus  

ERIC Educational Resources Information Center

|cAMP is a critical second messenger implicated in synaptic plasticity and memory in the mammalian brain. Substantial evidence links increases in intracellular cAMP to activation of cAMP-dependent protein kinase (PKA) and subsequent phosphorylation of downstream effectors (transcription factors, receptors, protein kinases) necessary for long-term…

Gelinas, Jennifer N.; Banko, Jessica L.; Peters, Melinda M.; Klann, Eric; Weeber, Edwin J.; Nguyen, Peter V.

2008-01-01

116

Effect of voltage and cyclic AMP on frequency of slow-wave-type action potentials in canine colon smooth muscle.  

PubMed Central

1. A non-L-type calcium conductance is involved in the generation of the initial part of the slow-wave-type action potential in colonic smooth muscle. The present study addresses the question whether this conductance is voltage or metabolically activated. 2. Current-induced hyperpolarization increased frequency and amplitude of slow waves measured in Krebs solution. 3. The upstroke potential was 'isolated' from the slow wave by superfusion with 'glucamine-nitrendipine' Krebs solution (NaCl was replaced by glucamine, nitrendipine was added). 4. Hyperpolarization up to -100 mV did not affect the upstroke potential frequency and increased its amplitude. Only hyperpolarization further than -100 mV decreased the frequency less than or equal to 20%, and reduced the amplitude less than or equal to 20%. 5. Depolarization did not affect the upstroke potential frequency. 6. Forskolin, but not 1,9-dideoxyforskolin dramatically decreased the upstroke potential frequency, without affecting other parameters including the resting membrane potential. 7. The effect of forskolin was mimicked by dibutyryl cyclic AMP, 8-bromo-cyclic AMP and 3-isobutyl-1-methylxanthine (IBMX), but not extracellular cyclic AMP. 8. The upstroke potential could not be evoked by depolarizing pulses after inhibition of activity by forskolin. 9. The effect of forskolin could be reversed by the calcium ionophore A23187. 10. In summary, voltage changes up to -40 mV and down to -100 mV do not, but changes in intracellular cyclic AMP do affect the frequency of the upstroke potential. 11. It is likely that intracellular metabolic activity, which may include cyclic AMP but not a voltage change, activates the conductance responsible for the generation of the upstroke potential.

Huizinga, J D; Farraway, L; Den Hertog, A

1991-01-01

117

The induction, desensitization and de-induction of tyrosine aminotransferase by 8-bromo-cyclic AMP in rat hepatoma cells.  

PubMed Central

Addition of 1-3 mM-8-bromo-cyclic AMP to monolayer cultures of H-4 rat hepatoma cells resulted in a rapid but short-lived increase in tyrosine aminotransferase (EC 2.6.1.5) activity. The transient nature of this induction is due to desensitization to 8-bromo-cyclic AMP. Throughout this time course of induction and desensitization, removal of 8-bromo-cyclic AMP resulted in a rapid and significant decrease in tyrosine aminotransferase activity, a process referred to as 'de-induction' in this study. We showed that the changes in tyrosine aminotransferase activity in its induction, desensitization and de-induction by 8-bromo-cyclic AMP were directly attributable to changes in the synthesis rate of the protein, and the amount of translatable and hybridizable mRNA encoding for tyrosine aminotransferase (mRNATAT). We further showed that this desensitization was specific to cyclic AMP. First, only active analogues of cyclic AMP and agents which increased cellular concentrations of cyclic AMP elicited this desensitization. Second, the desensitized cells were refractory only to the effects of 8-bromo-cyclic AMP; dexamethasone and insulin induced the tyrosine aminotransferase activity in the 8-bromo-cyclic AMP-desensitized cells in a manner similar to that of the controls. Studies on the metabolism of 8-bromo-cyclic AMP suggest that neither its degradation nor the accumulation of its primary metabolite, 8-bromoadenosine, played a significant role in modulating the expression of tyrosine aminotransferase during the time course of action of 8-bromo-cyclic AMP. These results provide evidence for a specific pretranslational mode of action of cyclic AMP in the control of tyrosine aminotransferase expression in its desensitization and de-induction, in addition to the early phase of induction. Images Fig. 1. Fig. 2. Fig. 3.

Smith, J D; Liu, A Y

1988-01-01

118

Cyclic AMP response element-binding protein is implicated in IL6 production from arthritic synovial cells  

Microsoft Academic Search

Overproduction of interleukin (IL)-6 from synovial cells is critically involved in the pathogenesis of rheumatoid arthritis\\u000a (RA). Cyclic adenosine monophosphate (AMP) response element-binding protein (CREB), a leucine zipper transcription factor,\\u000a is expressed at a high level in synovial cells of patients with RA. Although CREB transactivates IL-6 expression in vascular\\u000a smooth muscle cells, the relation between CREB expression and IL-6

Akihiro Ishizu; Asami Abe; Yukiko Miyatake; Tomohisa Baba; Chihiro Iinuma; Utano Tomaru; Takashi Yoshiki

2010-01-01

119

Transcriptional regulation of urokinase-type plasminogen activator receptor by cyclic AMP in PL-21 human myeloid leukemia cells: comparison with the regulation by phorbol myristate acetate.  

PubMed

We investigated the effect of dibutyryl cyclic AMP (Bt2-cAMP) on urokinase-type plasminogen activator receptor (uPAR) expression in human PL-21 myeloid leukemia cells and compared it with the effect of phorbol myristate acetate (PMA). Flow cytometric analysis clearly demonstrated that Bt2-cAMP and PMA both induced the cell surface expression of uPAR. Northern analysis and nuclear run-on assay revealed that cAMP and PMA activated the uPAR gene transcription and both additively increased the uPAR mRNA level. However, actinomycin-D decay experiment showed that PMA, but not cAMP, prolonged the uPAR mRNA half-life. Furthermore, inhibition of the ongoing protein synthesis with cycloheximide abrogated completely the PMA-induced uPAR mRNA accumulation but only partially the induction by PMA plus cAMP, whereas the induction by cAMP alone was rather amplified, indicating that the de novo protein synthesis is necessary in the induction by PMA but not in the induction by cAMP and that the cAMP pathway may be dominant in uPAR gene expression in the PL-21 cells as compared to the PMA pathway. These results suggest that cAMP induces the uPAR expression exclusively through activating the gene transcription in which a preexisting transcriptional factor may be involved, whereas PMA transcriptionally and posttranscriptionally regulates the uPAR gene expression. PMID:9531044

Niiya, K; Ozawa, T; Tsuzawa, T; Ueshima, S; Matsuo, O; Sakuragawa, N

1998-03-01

120

Phosphorylation of CREB, a cyclic AMP responsive element binding protein, contributes partially to lysophosphatidic acid-induced fibroblast cell proliferation  

SciTech Connect

Lysophospholipids regulate a wide array of biological processes including cell survival and proliferation. In our previous studies, we found that in addition to SRE, CRE is required for maximal c-fos promoter activation triggered by lysophosphatidic acid (LPA). c-fos is an early indicator of various cells into the cell cycle after mitogenic stimulation. However, role of CREB activation in LPA-stimulated proliferation has not been elucidated yet. Here, we investigate how LPA induces proliferation in Rat-2 fibroblast cell via CREB activation. We found that total cell number and BrdU-positive cells were increased by LPA. Moreover, levels of c-fos mRNA and cyclin D1 protein were increased via LPA-induced CREB phosphorylation. Furthermore, LPA-induced Rat-2 cell proliferation was decreased markedly by ERK inhibitor (U0126) and partially by MSK inhibitor (H89). Taken together, these results suggest that CREB activation could partially up-regulate accumulation of cyclin D1 protein level and proliferation of LPA-stimulated Rat-2 fibroblast cells.

Kwon, Yong-Jun; Sun, Yuanjie; Kim, Nam-Ho [Department of Pharmacology, College of Medicine, Institute of Natural Medicine, Hallym University, Chunchon, Gangwon-do 200-702 (Korea, Republic of); Huh, Sung-Oh [Department of Pharmacology, College of Medicine, Institute of Natural Medicine, Hallym University, Chunchon, Gangwon-do 200-702 (Korea, Republic of)], E-mail: s0huh@hallym.ac.kr

2009-03-13

121

Mesoporous silica nanoparticle-based double drug delivery system for glucose-responsive controlled release of insulin and cyclic AMP.  

PubMed

A boronic acid-functionalized mesoporous silica nanoparticle-based drug delivery system (BA-MSN) for glucose-responsive controlled release of both insulin and cyclic adenosine monophosphate (cAMP) was synthesized. Fluorescein isothiocyanate-labeled, gluconic acid-modified insulin (FITC-G-Ins) proteins were immobilized on the exterior surface of BA-MSN and also served as caps to encapsulate cAMP molecules inside the mesopores of BA-MSN. The release of both G-Ins and cAMP was triggered by the introduction of saccharides. The selectivity of FITC-G-Ins release toward a series of carbohydrate triggers was determined to be fructose > glucose > other saccharides. The unique feature of this double-release system is that the decrease of FITC-G-Ins release with cycles can be balanced by the release of cAMP from mesopores of MSN, which is regulated by the gatekeeper effect of FITC-G-Ins. In vitro controlled release of cAMP was studied at two pH conditions (pH 7.4 and 8.5). Furthermore, the cytotoxicity of cAMP-loaded G-Ins-MSN with four different cell lines was investigated by cell viability and proliferation studies. The cellular uptake properties of cAMP-loaded FITC-BA-MSN with and without G-Ins capping were investigated by flow cytometry and fluorescence confocal microscopy. We envision that this glucose-responsive MSN-based double-release system could lead to a new generation of self-regulated insulin-releasing devices. PMID:19476380

Zhao, Yannan; Trewyn, Brian G; Slowing, Igor I; Lin, Victor S-Y

2009-06-24

122

The Midbrain Periaqueductal Gray and Fear Extinction: Opioid Receptor Subtype and Roles of Cyclic AMP, Protein Kinase A, and Mitogen-Activated Protein Kinase  

Microsoft Academic Search

Four experiments studied the opioid receptor subtype and signal transduction mechanisms mediating fear extinction in the ventrolateral quadrant of the midbrain periaqueductal gray (vlPAG). Microinjection of a ?- but not a ?- or ?-opioid receptor antagonist into the vlPAG retarded extinction. Extinction was also dose-dependently retarded by vlPAG infusions of a cyclic AMP (cAMP) analog but was unaffected by infusions

Gavan P. McNally; Boo-Wahl Lee; Janet Y. Chiem; Eun A. Choi

2005-01-01

123

Cyclic AMP induces maturation of trout sperm axoneme to initiate motility  

NASA Astrophysics Data System (ADS)

Cyclic AMP has long been implicated as an activator of sperm motility1-5. From more recent experiments using demembranated mammalian and sea urchin spermatozoa6,7, it was concluded that cyclic AMP only increases the motility of the axoneme after it has been initiated by MgATP2-. We have now carried out similar experiments using spermatozoa collected from the rainbow trout and demembranated by treatment with the detergent Triton X-100. Our results suggest that in this species, cyclic AMP is required before MgATP2- to trigger maturation of the nonmotile axoneme. Subsequent addition of an energy source then induces motility.

Morisawa, Masaaki

1982-02-01

124

Direct Transcriptional Control of the Plasminogen Activator Gene of Yersinia pestis by the Cyclic AMP Receptor Protein  

Microsoft Academic Search

Horizontal gene transfer events followed by proper regulatory integration of a gene drive rapid evolution of bacterial pathogens. A key event in the evolution of the highly virulent plague bacterium Yersinia pestis was the acquisition of plasmid pPCP1, which carries the plasminogen activator gene, pla. This promoted the bubonic form of the disease by increasing bacterial dissemination from flea bite

Tae-Jong Kim; Sadhana Chauhan; Vladimir L. Motin; Ee-Been Goh; Michele M. Igo; Glenn M. Young

2007-01-01

125

Roles of hinge region, loops 3 and 4 in the activation of Escherichia coli cyclic AMP receptor protein  

Microsoft Academic Search

The cAMP receptor protein (CRP) requires cAMP for an allosteric change and regulates more than 150 genes in Escherichia coli. In this study, the modular half of cAMP receptor protein was used to investigate the allosteric signal transmission pathway induced by cAMP binding. The activation of CRP upon cAMP binding is indicated to be realignment of the two subunits within

Zhengya Gao; Feng Li; Guangrong Wu; Yanrun Zhu; Ting Yu; Shaoning Yu

126

Cyclic AMP-sensitive activation of hepatic sterol synthesis and 3-hydroxy-3-met hylg I utaryl coenzyme A reductase  

Microsoft Academic Search

We previously showed that preincubation of a 10,000 g supernatant (Slo) from rat liver for 20 min at 37°C dramatically increased the subsequent incorporation of (14C)acetate into sterols. No activation was seen with (14C)mev- alonate as substrate. In the present studies we have examined the effect of preincubation on HMG CoA reductase. When microsomes were isolated from Slo by calcium

Charles D. Goodwin; Simeon Margolis

127

The Effect of Cyclic AMP on the Permeability Characteristics of the Escherichia coli Membrane System.  

National Technical Information Service (NTIS)

Various metabolic functions associated with the Escherichia coli membrane system were analyzed in mutant strains lacking adenylate cyclase (cya mutations) or cyclic AMP binding protein (CRP) activity (crp mutations). Mutations which have suppressed the or...

W. J. Dobrogosz

1977-01-01

128

Cyclic AMP Analog Blocks Kinase Activation by Stabilizing Inactive Conformation: Conformational Selection Highlights a New Concept in Allosteric Inhibitor Design*  

PubMed Central

The regulatory (R) subunit of protein kinase A serves to modulate the activity of protein kinase A in a cAMP-dependent manner and exists in two distinct and structurally dissimilar, end point cAMP-bound “B” and C-subunit-bound “H”-conformations. Here we report mechanistic details of cAMP action as yet unknown through a unique approach combining x-ray crystallography with structural proteomics approaches, amide hydrogen/deuterium exchange and ion mobility mass spectrometry, applied to the study of a stereospecific cAMP phosphorothioate analog and antagonist((Rp)-cAMPS). X-ray crystallography shows cAMP-bound R-subunit in the B form but surprisingly the antagonist Rp-cAMPS-bound R-subunit crystallized in the H conformation, which was previously assumed to be induced only by C-subunit-binding. Apo R-subunit crystallized in the B form as well but amide exchange mass spectrometry showed large differences between apo, agonist and antagonist-bound states of the R-subunit. Further ion mobility reveals the apo R-subunit as an ensemble of multiple conformations with collisional cross-sectional areas spanning both the agonist and antagonist-bound states. Thus contrary to earlier studies that explained the basis for cAMP action through “induced fit” alone, we report evidence for conformational selection, where the ligand-free apo form of the R-subunit exists as an ensemble of both B and H conformations. Although cAMP preferentially binds the B conformation, Rp-cAMPS interestingly binds the H conformation. This reveals the unique importance of the equatorial oxygen of the cyclic phosphate in mediating conformational transitions from H to B forms highlighting a novel approach for rational structure-based drug design. Ideal inhibitors such as Rp-cAMPS are those that preferentially “select” inactive conformations of target proteins by satisfying all “binding” constraints alone without inducing conformational changes necessary for activation.

Badireddy, Suguna; Yunfeng, Gao; Ritchie, Mark; Akamine, Pearl; Wu, Jian; Kim, Choel W.; Taylor, Susan S.; Qingsong, Lin; Swaminathan, Kunchithapadam; Anand, Ganesh S.

2011-01-01

129

Simvastatin suppresses leptin expression in 3T3-L1 adipocytes via activation of the cyclic AMP-PKA pathway induced by inhibition of protein prenylation.  

PubMed

Simvastatin inhibits 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which catalyses conversion of HMG-CoA to mevalonate, a rate-limiting step in cholesterol synthesis. We demonstrated that simvastatin at 1 microM markedly inhibited adipocyte differentiation measured by Oil Red O staining in preadipocyte cells (3T3-L1), while expression of leptin, a marker of adipocyte differentiation, was suppressed by 1 muM simvastatin for up to 12 days of culture. Next, to elucidate mechanisms underlying the reduction of leptin expression induced by simvastatin, differentiated 3T3-L1 adipocytes were treated with various inhibitors with mevalonate or its metabolite in the presence or absence of simvastatin. Simvastatin time- and dose-dependently suppressed leptin mRNA expression. Heterogeneous nuclear RNA related to leptin mRNA was inhibited by 10 muM simvastatin, while stability of the mRNA was not changed by treatment with simvastatin in transcription-arrested 3T3-L1 cells. Simvastatin inhibition of leptin gene transcription was not abrogated by pre-treatment with cycloheximide, an inhibitor of protein synthesis. Addition of mevalonate or geranylgeranyl pyrophosphate (GGPP), a mevalonate metabolite, abolished simvastatin-induced inhibition of leptin expression in 3T3-L1 cells. Suppression of expression was observed upon addition of GGTI-298, a geranylgeranyl transferase I inhibitor, but not FTI-277, a farnesyl transferase inhibitor. Expression was suppressed by treatment with hydroxyfasudil, a protein prenylation inhibitor. Treatment with phosphatidylinositol 3-kinase (PI3K) inhibitors, LY294002 and wortmannin, reduced leptin expression in 3T3-L1 cells. Simvastatin dose-dependently increased intra-cellular cyclic AMP (cAMP) concentrations in 3T3-L1 cells, with maximal stimulation obtained at 10 muM. Addition of GGPP abolished simvastatin-induced stimulation of cAMP accumulation and protein kinase A (PKA) activity. H89, an inhibitor of PKA, completely abolished simvastatin-induced suppression of leptin expression. These results suggested that simvastatin reduced geranylgeranylprotein prenylation followed by deactivation of PI3K, leading to cAMP accumulation and subsequent activation of PKA in differentiated 3T3-L1 adipocytes. Finally, PKA inhibited leptin gene transcription without new protein synthesis. PMID:19254925

Maeda, Toyonobu; Horiuchi, Noboru

2009-03-02

130

Cyclic AMP level in red blood cells of Plasmodium berghei-infected Mastomys natalensis.  

PubMed

The present report describes the changes in cyclic AMP level which occur upon parasitization of red cells by Plasmodium berghei. Parasitized erythrocytes were separated from the non-parasitized population by percoll density-gradient centrifugation. An increase in the cyclic AMP content of both non-parasitized and parasitized erythrocytes of infected animals compared with that of uninfected animals was observed. The patterns of physiological response to isoproterenol in normal, parasitized and non-parasitized erythrocytes were identical. PMID:1849086

Khare, S; Ghatak, S

1991-03-15

131

P2Y receptor activation enhances insulin release from pancreatic beta-cells by triggering the cyclic AMP/protein kinase A pathway.  

PubMed

Adenine nucleotides stimulate insulin secretion by binding to P2 receptors of the pancreatic beta-cells; the stimulus-secretion coupling is not yet clearly established and may depend on the receptor subtype. The aim of the present study was to further investigate the mechanism whereby P2Y receptor agonists enhance glucose-induced insulin secretion. Experiments were performed in rat pancreatic islets and in the INS-1 secreting cell line in the presence of a slightly stimulating glucose concentration (8.3 mmol/l). In isolated islets, the P2Y receptor agonist ADPbetaS (50 micromol/l) induced a significant fivefold increase in the cyclic AMP (cAMP) content, from 43.4+/-3.7 fmol/10 islets in controls to 210.6+/-12.0; it still induced a 4.5-fold increase in cAMP content in the absence of calcium. In another series of experiments, ADPbetaS (50 micromol/l) significantly increased glucose-induced insulin secretion from 7.7+/-0.6 ng/3 islets in controls to 11.2+/-1.0. The adenylyl cyclase inhibitor SQ 22,536 (9-[tetrahydro-2-furanyl]-9 H-purin-6-amine; 100 micromol/l), which was ineffective alone, completely prevented the stimulating effect of ADPbetaS. In a set of experiments in which ADPbetaS increased glucose-induced insulin secretion from 10.0+/-0.7 ng/3 islets to 12.6+/-0.8, the inhibitor of cAMP-dependent protein kinase, TPCK (tos-phe-chloromethylketone; 3 micromol/l), which was ineffective alone, also prevented the stimulating effect of ADPbetaS. In incubated INS-1 cells, the P2Y receptor ligand ATPalphaS increased significantly both the content of cAMP and the release of insulin, in a concentration-dependent manner in the range of 50-150 micromol/l; the insulin release was significantly correlated with the cAMP content. In conclusion, the present results show that P2Y receptor agonists, ADPbetaS and ATPalphaS, amplify glucose-induced insulin secretion by activating beta-cell adenylyl cyclase and the subsequent cAMP/protein kinase A signaling pathway. PMID:12382076

Chevassus, H; Roig, A; Belloc, C; Lajoix, A-D; Broca, C; Manteghetti, M; Petit, P

2002-09-06

132

A cluster of phosphorylation sites on the cyclic AMP-regulated nuclear factor CREB predicted by its sequence  

Microsoft Academic Search

Cyclic AMP regulates the expression of a number of genes through a conserved promoter element, the CRE1. Moreover, transcrip-tional induction by cAMP requires the activation of cAMP-dependent protein kinase (protein kinase A)1,2. We have previously characterized the cAMP response element binding protein (CREB) in PC 12 cells and brain tissue as a nuclear factor, of relative molecular mass 43,000, whose

Gustavo A. Gonzalez; Karen K. Yamamoto; Wolfgang H. Fischer; David Karr; Patricia Menzel; William Biggs III; Wylie W. Vale; Marc R. Montminy

1989-01-01

133

Effects of forskolin analogs, phosphodiesterase inhibitors and 8-bromo cyclic AMP on plasma exudations induced with bradykinin and prostaglandin E/sub 1/ in rat skin  

SciTech Connect

The effects of forskolin analogs, phosphodiesterase inhibitors and 8-bromo cyclic AMP on plasma exudations induced with bradykinin and prostaglandin E/sub 1/ in rat skin were investigated using (/sup 125/I) bovine serum albumin (/sup 125/I-BSA). Forskolin, forskolin 7-ethyl carbonate and 7-desacetylforskolin, which are potent activators of adenylate cyclase, greatly potentiated the bradykinin-induced plasma exudation and inhibited the prostaglandin E/sub 1/-induced response. The phosphodiesterase inhibitors, ZK 627ll, dipyridamole, HL 725, and 3-isobutyl-1-methylxanthine potentiated the bradykinin-induced plasma exudation and inhibited and prostaglandin E/sub 1/-induced response. 8-Bromo cyclic AMP in the doses of 0.01 to 1 ..mu..g potentiated the bradykinin-induced plasma exudation, but had no effect at doses of 10 and 100 ..mu..g. 8-bromo cyclic AMP at all doses significantly inhibited the prostaglandin E/sub 1/-induced response. The results suggest that the effects of forskolin and its analogs on plasma exudations induced with bradykinin and prostaglandin E/sub 1/ in rat skin derive from activation of cyclic AMP-generating systems.

Sugio, K.; Daly, J.W.

1984-01-09

134

Relaxing and inotropic effects of cyclic AMP on skinned cardiac cells  

Microsoft Academic Search

THE positive inotropic effect of catecholamines in cardiac muscle is assumed to result from an increase in the intracellular level of cyclic AMP (adenosine 3',5'-monophosphate)1,2. Cyclic AMP may enhance the contraction by increasing the trans-sarcolemmal flux of Ca2+ during the plateau of the action potential3,4, but the flux seems insufficient to activate directly the myofilaments and it is generally assumed

Alexandre Fabiato; Francoise Fabiato

1975-01-01

135

Sgt1p Contributes to Cyclic AMP Pathway Activity and Physically Interacts with the Adenylyl Cyclase Cyr1p\\/Cdc35p in Budding Yeast  

Microsoft Academic Search

Sgt1p is a highly conserved eucaryotic protein that is required for both SCF (Skp1p\\/Cdc53p-Cullin-F-box)- mediated ubiquitination and kinetochore function in yeast. We show here that Sgt1p is also involved in the cyclic AMP (cAMP) pathway in Saccharomyces cerevisiae. SGT1 is an allele-specific suppressor of cdc35-1 ,a thermosensitive mutation in the leucine-rich repeat domain of the adenylyl cyclase Cyr1p\\/Cdc35p. We dem-

Caroline Dubacq; Raphael Guerois; Regis Courbeyrette; Katsumi Kitagawa; Carl Mann

2002-01-01

136

Cannabinoid Receptor Type 1- and 2-mediated Increase in Cyclic AMP Inhibits T Cell Receptor-triggered Signaling*  

PubMed Central

The aim of this study was to characterize inhibitory mechanisms on T cell receptor signaling mediated by the cannabinoid receptors CB1 and CB2. Both receptors are coupled to Gi/o proteins, which are associated with inhibition of cyclic AMP formation. In human primary and Jurkat T lymphocytes, activation of CB1 by R(+)-methanandamide, CB2 by JWH015, and both by ?9-tetrahydrocannabinol induced a short decrease in cyclic AMP lasting less than 1 h. However, this decrease was followed by a massive (up to 10-fold) and sustained (at least up to 48 h) increase in cyclic AMP. Mediated by the cyclic AMP-activated protein kinase A and C-terminal Src kinase, the cannabinoids induced a stable phosphorylation of the inhibitory Tyr-505 of the leukocyte-specific protein tyrosine kinase (Lck). By thus arresting Lck in its inhibited form, the cannabinoids prevented the dephosphorylation of Lck at Tyr-505 in response to T cell receptor activation, which is necessary for the subsequent initiation of T cell receptor signaling. In this way the cannabinoids inhibited the T cell receptor-triggered signaling, i.e. the activation of the ?-chain-associated protein kinase of 70 kDa, the linker for activation of T cells, MAPK, the induction of interleukin-2, and T cell proliferation. All of the effects of the cannabinoids were blocked by the CB1 and CB2 antagonists AM281 and AM630. These findings help to better understand the immunosuppressive effects of cannabinoids and explain the beneficial effects of these drugs in the treatment of T cell-mediated autoimmune disorders like multiple sclerosis.

Borner, Christine; Smida, Michal; Hollt, Volker; Schraven, Burkhart; Kraus, Jurgen

2009-01-01

137

Role of ecdysone, pupariation factors, and cyclic AMP in formation and tanning of the puparium of the fleshfly Sarcophaga bullata.  

PubMed

Two pupariation factors, anterior retraction factor (ARF) and puparium tanning factor (PTF), are absent from the hemolymph of larvae at the time of tanning accelerated by ARF/PTF, cyclic AMP, or dopamine. ARF and PTF are not involved in derepression of dopa decarboxylase (aromatic L-amino-acid decarboxylase, aromatic L-amino-acid carboxy-lyase, EC 4.1.1.28) synthesis initiated by ecdysone. Tanning is entirely inhibited by injection of two transcriptional inhibitors, actinomycin and BrdUrd, and two translational inhibitors, puromycin and cycloheximide. Retraction activity is more severely inhibited by the transcriptional than by the translational inhibitors. A tanning response is initiated by cyclic AMP in the presence of the transcriptional but not the translational inhibitors. Dihydric tanning substances (dopa, dopamine) initiate tanning in the presence of both types of inhibitors. Release of ARF and PTF from the central nervous system is inhibited by the four inhibitors. ARF totally reverses the inhibitory effects on retraction, whereas PTF does not reverse inhibition of tanning. These data are interpreted to mean that PTF is concerned with the regulation of two components of the tanning response: (i) acceleration of synthesis of a particular protein (associated with the tyrosine hydroxylation complex), and (ii) activation via cyclic AMP of a component of the tyrosine hydroxylating system. PMID:16592458

Seligman, M; Blechl, A; Blechl, J; Herman, P; Fraenkel, G

1977-10-01

138

21 CFR 862.1230 - Cyclic AMP test system.  

Code of Federal Regulations, 2010 CFR

...2012-04-01 2012-04-01 false Cyclic AMP test system. 862.1230 Section 862.1230...Chemistry Test Systems § 862.1230 Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure...

2012-04-01

139

Cyclic AMP and cyclic AMP-receptor protein modulate the autoinducer-2-mediated quorum sensing system in Vibrio vulnificus.  

PubMed

This study was undertaken to determine whether cyclic AMP (cAMP) or cAMP-receptor protein (CRP) modulates the activity of the autoinducer (AI)-2-mediated quorum sensing (QS) system in response to glucose availability in Vibrio vulnificus. A mutation in crp impaired V. vulnificus growth, decreased AI-2 production, and repressed the expression of smcR encoding the master regulator SmcR (a Vibrio harveyi LuxR homolog) of the AI-2-QS system, and these changes were prevented by in trans complementation of wild-type crp. Furthermore, glucose repressed smcR expression in the presence of CRP but not in its absence. A mutation in cyaA encoding adenylate cyclase, which is required for cAMP synthesis, also impaired V. vulnificus growth and repressed smcR expression, and these changes were recovered by in trans complementation of wild-type cyaA. These results indicate that cAMP or CRP modulates the AI-2-QS system in response to glucose availability in V. vulnificus, demonstrating the presence of a connection between catabolite repression and quorum sensing in V. vulnificus. PMID:22961036

Kim, Sun-Pyo; Kim, Choon-Mee; Shin, Sung-Heui

2012-09-09

140

Schwann cells express IP prostanoid receptors coupled to an elevation in intracellular cyclic AMP.  

PubMed

We have shown previously that prostaglandin E(2) (PGE(2)) and prostaglandin I(2) (PGI(2)) are each produced in an explant model of peripheral nerve injury. We report that IP prostanoid receptor mRNA and protein are present in primary rat Schwann cells. IP prostanoid receptor stimulation using prostacyclin produced an elevation in intracellular cyclic AMP concentration ([cAMP](i)) in primary Schwann cells. Peak [cAMP](i) was observed between 5-15 min of stimulation followed by a gradual recovery toward basal level. Phosphorylation of cyclic AMP-response element binding protein (CREB) on Ser(133) was also detected after IP prostanoid receptor stimulation and CREB phosphorylation was inhibited completely by the protein kinase A inhibitor, H-89. Intracellular calcium levels were not affected by IP prostanoid receptor stimulation. Unlike forskolin, IP prostanoid receptor stimulation did not significantly augment Schwann cell proliferation in response to growth factor treatment. However, IP prostanoid receptor stimulation increased the number of Schwann cells that were able to generate a calcium transient in response to P2 purinergic receptor activation. These findings suggest that signaling via the IP prostanoid receptor may by relevant to Schwann cell biology in vivo. PMID:17335081

Muja, Naser; Nelson, Julie K; DeVries, George H

2007-05-01

141

3':5'-cyclic AMP and hormonal control of puparium formation in the fleshfly Sarcophaga bullata.  

PubMed

Injection of 3':5'-cyclic AMP (cAMP) into larvae of the fly Sarcophaga bullata 3-4 hr before the beginning of puparium formation (red-spiracle stage) greatly accelerates the onset of tanning without affecting initiation of puparium formation (anterior retraction). Accelerated tanning resembles real tanning in two important respects: the solubility of cuticular proteins becomes reduced and [U-14C]tyrosine is incorporated into the cuticle. Of a number of cAMP analogues tested, 3':5'- cyclic GMP, 2':3'-cyclic AMP, and 5'-AMP were inactive, dibutyryl-3':5'-cAMP had only slight activity, and cyclic IMP and deoxy-3':5'-cAMP showed some activity. Theophylline enhanced the effect of small doses of cAMP or of blood, diluted 1:8, active in the puparium tanning factor. Injection of dopa, dopamine, acetyldopamine, or epinephrine, but not of tyrosine, had an accelerating effect similar to that of cAMP. The tanning-inhibiting effect of DL-alpha-methyl-alpha-hydrazino-beta-(3,4-dihydroxyphenyl)propionic acid monohydrate is reversed by dopamine or epinephrine, but not by tyrosine, dopa, or cAMP. Evidence is presented to indicate that the responses to cAMP are not artifacts but reflect actual biochemical events during tanning. PMID:194250

Fraenkel, G; Blechl, A; Blechl, J; Herman, P; Seligman, M I

1977-05-01

142

Regulation of Cyclic GMP, Cyclic amp and Lactate Dehydrogenase by Putative Neutrotransmitters in the C6 Rat Glioma Cell Line.  

National Technical Information Service (NTIS)

In C6 cells norepinephrine and dopamine caused transient increases in cyclic GMP and cyclic AMP, as well as an induction of lactate dehydrogenase. All of these responses were blocked by 1-propranolol, suggesting mediation by a beta -receptor. Phentolamine...

J. E. Bottenstein J. de Vellis

1977-01-01

143

Dopaminergic stimulation of cyclic AMP accumulation and parathyroid hormone release from dispersed bovine parathyroid cells  

PubMed Central

The effects of dopaminergic agonists and antagonists have been studied in dispersed bovine parathyroid cells. Dopaminergic agonists caused a transient 20- to 40-fold increase in cellular cyclic AMP and a 2- to 3-fold increase in parathyroid hormone release. Dose-response relationships were similar for cyclic AMP accumulation and hormone release, whether studied by increasing agonist concentration or by increasing concentration of antagonist with constant agonist. The effects on the dopamine receptor could be differentiated from those of the previously characterized ?-adrenergic receptor by specific inhibitors. These results appear to represent proof with a homogeneous cell population that dopaminergic receptors linked to adenylate cyclase can regulate a secretory process mediated by cyclic AMP. This system should be useful in further studies on dopamine receptors and should provide a valid tool for determining interactions of radiolabeled ligands with such receptors.

Brown, E. M.; Carroll, R. J.; Aurbach, G. D.

1977-01-01

144

An AP-2 element acts synergistically with the cyclic AMP- and Phorbol ester-inducible enhancer of the human proenkephalin gene  

SciTech Connect

An enhancer with two DNA elements, one containing the sequence CGTCA, is required for cyclic AMP-and phorbol ester-inducible transcription of the human proenkephalin gene. The authors report that an AP-2 element located adjacent to the enhancer acts synergistically with it to confer maximal response to cyclic AMP and phorbol esters.

Hyman, S.E.; Comb, M.; Pearlberg, J.; Goodman, H.M.

1989-01-01

145

Chloride permeability regulation via a cyclic AMP pathway in cultured human sweat duct cells.  

PubMed Central

1. Isolated coiled reabsorptive sweat ducts from normal subjects and patients with cystic fibrosis (CF) were cultured in vitro. Cells were harvested and plated onto permeable supports to form confluent cell sheets. The Ussing chamber technique was used to study pharmacological regulation of the transepithelial ion transport in these membranes. 2. Addition of a stable cyclic AMP analogue, 8-Br-cyclic AMP, to normal cell cultures resulted in a decrease of the transepithelial potential difference (PD). 3. Forskolin exposure resulted in a similar PD decrease, which was augmented by the phosphodiesterase inhibitor, isobutylmethylxanthine (IBMX). 4. Exposure to isoprenaline, prostaglandin E2 (PGE2), and phenylephrine resulted in a response mimicking the forskolin-induced response, that was also amplified by IBMX. 5. Pre-incubation with cholera toxin abolished the isoprenaline response and reduced the control resistance. 6. Propranolol abolished the responses induced by isoprenaline and phenylephrine, whereas phentolamine had no effect. PGE2-induced responses were inert to both types of blockers. 7. Indomethazine addition to an unstimulated membrane resulted in a weak PD increase, i.e. a response opposite to that induced by isoprenaline. 8. IBMX addition to an unstimulated membrane resulted in a weak isoprenaline-like response. When the cells were pre-treated with indomethazine this IBMX response was absent. 9. Unidirectional Cl- isotope flux studies demonstrated a large increase of net Cl- reabsorption in response to isoprenaline and PGE2. 10. Mannitol isotope flux studies revealed that the paracellular permeability was unaffected by isoprenaline exposure. 11. Membranes derived from CF patients did not respond similarly to any of these agents. However, a weak spike, occasionally followed by a gradual increase of the short-circuit current (Iscc), was observed in both normal subjects and CF patients. 12. It is concluded that the primary effect on ion transport of factors increasing the cyclic AMP in normal cultured sweat duct cells is an activation of a transcellular Cl- permeability. This effect was missing in cells derived from CF patients.

Pedersen, P S

1990-01-01

146

Chloride permeability regulation via a cyclic AMP pathway in cultured human sweat duct cells.  

PubMed

1. Isolated coiled reabsorptive sweat ducts from normal subjects and patients with cystic fibrosis (CF) were cultured in vitro. Cells were harvested and plated onto permeable supports to form confluent cell sheets. The Ussing chamber technique was used to study pharmacological regulation of the transepithelial ion transport in these membranes. 2. Addition of a stable cyclic AMP analogue, 8-Br-cyclic AMP, to normal cell cultures resulted in a decrease of the transepithelial potential difference (PD). 3. Forskolin exposure resulted in a similar PD decrease, which was augmented by the phosphodiesterase inhibitor, isobutylmethylxanthine (IBMX). 4. Exposure to isoprenaline, prostaglandin E2 (PGE2), and phenylephrine resulted in a response mimicking the forskolin-induced response, that was also amplified by IBMX. 5. Pre-incubation with cholera toxin abolished the isoprenaline response and reduced the control resistance. 6. Propranolol abolished the responses induced by isoprenaline and phenylephrine, whereas phentolamine had no effect. PGE2-induced responses were inert to both types of blockers. 7. Indomethazine addition to an unstimulated membrane resulted in a weak PD increase, i.e. a response opposite to that induced by isoprenaline. 8. IBMX addition to an unstimulated membrane resulted in a weak isoprenaline-like response. When the cells were pre-treated with indomethazine this IBMX response was absent. 9. Unidirectional Cl- isotope flux studies demonstrated a large increase of net Cl- reabsorption in response to isoprenaline and PGE2. 10. Mannitol isotope flux studies revealed that the paracellular permeability was unaffected by isoprenaline exposure. 11. Membranes derived from CF patients did not respond similarly to any of these agents. However, a weak spike, occasionally followed by a gradual increase of the short-circuit current (Iscc), was observed in both normal subjects and CF patients. 12. It is concluded that the primary effect on ion transport of factors increasing the cyclic AMP in normal cultured sweat duct cells is an activation of a transcellular Cl- permeability. This effect was missing in cells derived from CF patients. PMID:1693399

Pedersen, P S

1990-02-01

147

Epidermal chalone and cyclic AMP: an in vivo study.  

PubMed

Water extracts of skin contain two factors that inhibit epidermal cell proliferation: one substance inhibits epidermal cells in the G2 phase (the epidermal G2 inhibitor), and another inhibits the transit of cells from the G1 phase into the S phase (the epidermal G1 inhibitor). Pretreatment of mice with a beta-receptor antagonist (propranolol) abolished the activity of the G2 inhibitor but not that of the G1 inhibitor. After pretreatment with both propranolol and a phosphodiesterase inhibitor (caffine)the G2 inhibitor had full effect. Cafine alone had a moderately inhibitory effect on epidermal G2 cells and enhanced the depressing effect of the G1 inhibitor on epidermal DNA synthesis. AMP level in epidermis to be active. Cyclic AMP is probably also involved in the regulation of the rate of transit of epidermal G1 cells into the S phase but the epidermal cyclic AMP level seems not to be so critical for the efficacy of the epidermal G2 inhibitor in epidermal cell differentiation. PMID:162919

Elgjo, K

1975-01-01

148

Injection of subunits of cyclic AMP-dependent protein kinase into cardiac myocytes modulates Ca2+ current  

Microsoft Academic Search

beta-Adrenergic stimulation of the heart is thought to increase cardiac muscle contractility by activation of cyclic AMP-dependent protein kinase and concomitant increase in the phosphorylation of certain proteins (for refs see refs 1-6). Electrophysiological studies have shown that the stimulation of cardiac beta-adrenoreceptors7, the external application of cyclic AMP or its analogues to Purkinje fibres8, or the injection of cyclic

W. Osterrieder; G. Brum; J. Hescheler; W. Trautwein; V. Flockerzi; F. Hofmann

1982-01-01

149

Effect of adenosine receptor agonists and other compounds on cyclic AMP accumulation in forskolin-treated hippocampal slices  

Microsoft Academic Search

1.The effect of adenosine analogues and some putative neurotransmitters have been studied on cyclic AMP accumulation in rat hippocampal slices treated with the adenylate cyclase activator forskolin.2.The effects of PGE2 and histamine were potentiated by forskolin (0.1 µM). Isoprenaline and NECA had essentially additive effects with 0.1 µM forskolin and serotonin (above 10-4 M) inhibited forskolin-stimulated cyclic AMP accumulation.3.The A1-adenosine

Bertil B. Fredholm; Bror Jonzon; Karin Lindström

1986-01-01

150

Cyclic AMP-dependent protein phosphorylation in isolated neuronal growth cones from developing rat forebrain.  

PubMed

We have shown recently that neuronal growth cones isolated from developing rat forebrain possess an appreciable activity of adenylate cyclase, which produces cyclic AMP and can be stimulated by various neurotransmitter receptor agonists and by forskolin. To investigate cyclic AMP-mediated biochemical mechanisms in isolated growth cones, we have centered the present study on cyclic AMP-dependent protein phosphorylation. One-dimensional gel electrophoretic analysis showed that cyclic AMP analogs increased incorporation of 32P into several phosphoproteins in molecular mass ranges of 50-58 and 76-82 kilodaltons, including those of 82, 76, and 51 kilodaltons. Two-dimensional electrophoresis, using isoelectric focusing in the first dimension, resolved phosphorylated alpha- and beta-tubulin species, actin, a very acidic protein (isoelectric point 4.0) with a molecular mass of 93 kilodaltons, and two proteins (x and x') closely neighboring beta-tubulin. Two other phosphoproteins seen in the gels had molecular masses of 56 and 51 kilodaltons (respective isoelectric points, 4.5 and 4.4) and, along with the 93-kilodalton phosphoprotein, were highly enriched in the isolated growth cones. Only the tubulin and actin species were major proteins in the isolated growth cones. Cyclic AMP analogs enhanced incorporation of 32P into phosphoproteins x and x', and, as assessed by immunoprecipitation, into beta-tubulin. Peptide digest experiments suggested that phosphoproteins x and x' are unrelated to beta-tubulin. Nonequilibrium two-dimensional electrophoresis resolved many phosphoproteins, of which a 79- and 75-kilodalton doublet, a 74-kilodalton species, and a 58-kilodalton doublet showed enhanced incorporation of 32P in the presence of cyclic AMP. PMID:2537377

Lockerbie, R O; Eddé, B; Prochiantz, A

1989-03-01

151

Overexpression and RNA interference of Ap-cyclic AMP-response element binding protein-2, a repressor of long-term facilitation, in Aplysia kurodai sensory-to-motor synapses.  

PubMed

cyclic AMP-response element binding protein-2 (CREB2) is a member of the CREB/transcription factor (CREB/ATF4) family. CREB2 is a transcription factor known to be involved in Aplysia long-term facilitation. To further examine the role of ApCREB2 on long-term synaptic facilitation, we isolated ApCREB2 from Aplysia kurodai in full-length cDNA library, and found that the overexpression of ApCREB2 blocked 5-hydroxytryptamine (5-HT)-induced long-term synaptic facilitation in Aplysia sensory-to-motor synapses. Furthermore, a single pulse of 5-HT, which normally induces only short-term facilitation, in the presence of ApCREB2 inhibition by RNA interference, induced long-term facilitation in Aplysia sensory-to-motor synapses. These results suggest that ApCREB2 is a functional repressor of long-term facilitation in Aplysia sensory-to-motor synapses. PMID:12524159

Lee, Jin-A; Kim, Hyoung; Lee, Yong-Seok; Kaang, Bong-Kiun

2003-01-30

152

Cyclic AMP mediates inhibition of the Na(+)-K+ electrogenic pump by serotonin in tactile sensory neurones of the leech.  

PubMed

1. Serotonin (5-HT) reduced the after-hyperpolarization (AHP) amplitude in tactile sensory neurones (T) but not in pressor (P) or nociceptive (N) cells of the leech. 2. Adenylate cyclase activators, phosphodiesterase inhibitors and membrane permeant analogues of cyclic adenosine monophosphate (cyclic AMP) mimicked the effect of 5-HT in reducing the AHP amplitude in T neurones. 3. Ionophoretic injection of cyclic AMP in T cells reduced the AHP amplitude, while cyclic guanosine monophosphate (cyclic GMP) or adenosine-5'-monophosphate (AMP) were without effect. 4. Inhibition of adenylate cyclase by the drug RMI 12330A (also known as MDL 12330A) suggested that 5-HT reduced the AHP amplitude through cyclic AMP. 5. 8-Bromoadenosine-3'-5'-cyclic monophosphate (8-Br-cyclic AMP) was still able to reduce the AHP amplitude after blocking the Ca(2+)-activated K+ conductance with CdCl2 and converted the normal hyperpolarization which follows the intracellular injection of Na+ into a depolarization. In addition, the cyclic AMP analogue slowed down and reduced the repolarization usually induced by CsCl after perfusion with K(+)-free solution. It is proposed that, in T sensory neurones, cyclic AMP mediates the inhibition of the Na(+)-K+ electrogenic pump induced by 5-HT application. PMID:7687293

Catarsi, S; Scuri, R; Brunelli, M

1993-03-01

153

Localization of catalytic and regulatory subunits of cyclic AMP-dependent protein kinases in mitochondria from various rat tissues.  

PubMed Central

Observation and quantification of the catalytic subunit C of cyclic AMP-dependent protein kinases by immuno-gold electron microscopy suggested a high concentration of cyclic AMP-dependent protein kinases in mitochondria from liver, kidney, heart and skeletal muscle, pancreas, parotid gland and brain cells. The position of gold particles pointed to a localization in the inner membrane/matrix space. A similar distribution was obtained by immunolocalization of the cyclic AMP-dependent protein kinase regulatory subunits RI and RII in liver, pancreas and heart cells. The results indicated the presence of both the type I and the type II cyclic AMP-dependent protein kinases in mitochondria of hepatocytes, and the preferential occurrence of the type I protein kinase in mitochondria from exocrine pancreas and heart muscle. The immunocytochemical results were confirmed by immunochemical determination of cyclic AMP-dependent protein kinase subunits in fractionated tissues. Determinations by e.l.i.s.a. of the C-subunit in parotid gland cell fractions indicated about a 4-fold higher concentration of C-subunit in the mitochondria than in a crude 1200 g supernatant. Immunoblot analysis of subfractions from liver mitochondria supported the localization in situ of cyclic AMP-dependent protein kinases in the inner membrane/matrix space and suggested that the type I enzyme is anchored by its regulatory subunit to the inner membrane. In accordance with the immunoblot data, the specific activity of cyclic AMP-dependent protein kinase measured in the matrix fraction was about twice that measured in whole mitochondria. These findings indicate the importance of cyclic AMP-dependent protein kinases in the regulation of mitochondrial functions. Images Fig. 1. Fig. 2. Fig. 3. Fig. 5.

Schwoch, G; Trinczek, B; Bode, C

1990-01-01

154

21 CFR 862.1230 - Cyclic AMP test system.  

Code of Federal Regulations, 2013 CFR

...false Cyclic AMP test system. 862.1230 Section...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...Clinical Chemistry Test Systems § 862.1230 Cyclic... A cyclic AMP test system is a device intended...plasma, urine, and other body fluids....

2013-04-01

155

Cyclic AMP, the Microtubule-Microfilament System, and Cancer  

Microsoft Academic Search

Additional evidence is presented for the previously proposed existence in normal fibroblasts of a cyclic AMP-dependent network of microtubules and microfilaments, which is connected with cell membrane elements on one end and with nuclear structures on the other and whose disorganization leads to malignant transformation. In the presence of cyclic AMP derivatives sufficient to promote integrity of this network, cell

Theodore T. Puck

1977-01-01

156

Stimulation of natural killer and antibody-dependent cellular cytotoxicity activities in mouse leukocytes by bombesin, gastrin-releasing peptide and neuromedin C: involvement of cyclic AMP, inositol 1,4,5-trisphosphate and protein kinase C.  

PubMed

Bombesin and the two mammalian bombesin-related peptides, gastrin-releasing peptide (GRP) and neuromedin C, at physiological concentrations ranging from 10(-11) M to 10(-9) M have been shown in this study to significantly stimulate in vitro the antibody-dependent cellular cytotoxicity (ADCC) and natural killer (NK) activities in BALB/c mouse leukocytes from axillary nodes, spleen and thymus. The three neuropeptides studied induced no change in interleukin-2 production. In addition, these neuropeptides induced in leukocytes from axillary nodes a rapid, transient and significant decrease of intracellular cyclic AMP at 30 s, but a significant transient increase of inositol 1,4,5-trisphosphate levels at 30 and 60 s and a stimulation of protein kinase C activity in membrane fractions after 5 min incubation. These results suggest that inositol phospholipid signalling and cAMP messenger systems are involved in the increase of NK and ADCC activities when leukocytes are incubated in the presence of bombesin, GRP or neuromedin C. PMID:8227312

De la Fuente, M; Del Rio, M; Hernanz, A

157

Adrenergic Drug Effects on Cyclic AMP in Cultured Human Trabecular Meshwork Cells  

Microsoft Academic Search

Cyclic AMP production in the presence or absence of various adrenergic agonists and antagonists was determined in cultured human trabecular cells using a gammaflow automated radioimmunoassay that allowed multiple simultaneous experiments and reproducible results. Adrenergic agonists and antagonists showed activation and inhibition constants consistent with the presence of ?2-receptors: Ka of isoproterenol < epinephrine < norepinephrine < phenylephrine; Ki of

Zvi Friedman; Ernest Bloom; Jon R. Polansky

1999-01-01

158

Cardiac muscle ultrastructure and cyclic AMP reactions to altered gravity conditions  

SciTech Connect

Morphological and biochemical analyses of heart muscle of rats subjected to microgravity on Spacelab 3(SL-3) flight and rats born and reared under increased gravity (1.7 G) conditions were compared with 1-G controls. Electronmicroscopic studies showed an increase in the number of lipid droplets and in areas of glycogen storage. Distribution changes of microtubules and cytoskeletal elements from both SL-3 and 1.7-G groups were observed. The high K/sub m/(2,8-/sup 3/H) cyclic AMP phosphodiesterase activity was lower in SL-3 heart muscle, and low K/sub m/ activity was lower in 1.7-G males but was unaltered in females. Cyclic AMP-dependent protein kinase (cA-PK) activity was decreased in subcellular fractions of heart muscle of SL-3 animals. Recompartmentalization of cA-PK activity occurred in particulate tissue fraction of 1.7-g animals (70.3% of total for 1.7 G vs. 35.9% for controls). Phosphorylation of endogenous low-mobility proteins increased in SL-3 heart-soluble fractions. Photoaffinity labeling (18 h, 4/sup 0/C) decreased in type II cA-PK regulatory (R) subunits in both SL-3 and in 1.7-G male heart tissue particulate fractions. The 1.7-G female heart R subunit distribution did not differ from controls. These findings indicate that in heart muscle altered gravity conditions influenced physiological reactions similar to catecholamine-induced receptor-mediated hormonal responses.

Mednieks, M.I.; Fine, A.S.; Oyama, J.; Philpott, D.E.

1987-02-01

159

Pathogenic Role of Cyclic AMP in the Impairment of Urinary Concentrating Ability in Acute Hypercalcemia  

PubMed Central

A possible association between the impairment of urinary concentrating ability and an impairment of the vasopressin-dependent cyclic AMP system in hypercalcemia was investigated in rat kidneys both in vivo and in vitro. The increases of urinary osmolality and negative free water clearance and the increase of urinary cyclic AMP excretion by vasopressin injection were significantly less in the hypercalcemic rats than in the control rats. The increase of cyclic AMP concentration by vasopressin in renal medullary tissue was significantly less in the slices obtained from the hypercalcem'c rats than in those obtained from the control rats. The activation of adenylate cyclase by vasopressin was significantly less in the group with an increased concentration of calcium in media than the control group, but phosphodiesterase activity was not affected by calcium concentration in the media. These data suggest that the impaired urinary concentrating ability in hypercalcemic kidneys is due at least in part to the direct inhibitory effect of calcium on the vasopressin-dependent cyclic AMP system at the level of adenylate cyclase in renal medulla.

Beck, Nama; Singh, Harbans; Reed, Sarah W.; Murdaugh, H. V.; Davis, Bernard B.

1974-01-01

160

Transcriptional regulation of the tyrosine hydroxylase gene by glucocorticoid and cyclic AMP  

SciTech Connect

Glucocorticoid and cyclic AMP increase tyrosine hydroxylase (TH) activity and mRNA levels in pheochromocytoma cultures. The transcriptional activity of the TH gene, as measured by nuclear run-on assay, is also increased when cultures are treated with the synthetic glucocorticoid dexamethasone or agents that increase intracellular cyclic AMP, such as forskolin and 8-BrcAMP. Both inducers effect transcriptional changes within 10 min after treatment and are maximal after 30 min for forskolin and after 60 min for dexamethasone. The 5' flanking sequences of the TH gene were fused to the bacterial gene chloramphenicol acetyltransferase (CAT), and the hybrid gene was transfected into pheochromocytoma cultures and GH/sub 4/ pituitary cells. In both cell lines, a region of the TH gene containing bases -272 to +27 conferred induction of CAT by cyclic AMP, but not by glucocorticoid. The same results were found when a region of the TH gene containing -773 to + 27 was used. Thus, the sequences required for induction of TH by cyclic AMP are contained within 272 bases of 5' flanking sequence, but sequences sufficient for glucocorticoid regulation are not contained with 773 bases.

Lewis, E.J.; Harrington, C.A.; Chikaraishi, D.M.

1987-06-01

161

Antidepressant- and anxiolytic-like effects of the phosphodiesterase-4 (PDE4) inhibitor rolipram on behavior depend on cyclic AMP-response element binding protein (CREB)-mediated neurogenesis in the hippocampus  

PubMed Central

Inhibition of phosphodiesterase-4 (PDE4), an enzyme that catalyzes the hydrolysis of cyclic AMP (cAMP), increases phosphorylation of cAMP-response element binding protein (pCREB) and hippocampal neurogenesis, and produces antidepressant-like effects on behavior; however, causal links among these have not been established. In the present study, chronic administration of rolipram produced antidepressant- and anxiolytic-like effects on behavior in mice. It also increased cAMP and pCREB levels in the hippocampus and prefrontal cortex, but increased Sox2, a marker for mitotic progenitor cells, only in the hippocampus. Chronic rolipram treatment also increased hippocampal neurogenesis, as evidenced by increased bromodeoxyuridine (BrdU)-positive cells in the hippocampal dentate gyrus. Methylazoxymethanol (MAM), which is toxic to proliferating cells, reversed rolipram-induced increases in BrdU-positive cells and pCREB in the hippocampus and partially blocked its behavioral effects. Approximately 84% of BrdU-positive cells became newborn neurons, 93% of which co-expressed pCREB; these proportions were not altered by rolipram or MAM, either alone or in combination. Finally, three weeks following the end of MAM treatment, when neurogenesis was no longer inhibited, rolipram again increased hippocampal pCREB, with its antidepressant- and anxiolytic-like effects resumed. Overall, the present results suggest that rolipram produces its effects on behavior in a manner that at least partially depends on its neurogenic action in the hippocampus, targeting mitotic progenitor cells rather than newborn or mature neurons; cAMP/CREB signaling in hippocampal newborn neurons is critical for neurogenesis and contributes to the behavioral effects of rolipram.

Li, Yun-Feng; Huang, Ying; Amsdell, Simon L.; Xiao, Lan; O'Donnell, James M.; Zhang, Han-Ting

2009-01-01

162

Differential Regulation of Matrix Metalloproteinase-9 and Tissue Plasminogen Activator Activity by the CyclicAMP System in Lipopolysaccharide-stimulated Rat Primary Astrocytes  

Microsoft Academic Search

We investigated the effect of the cAMP system on lipopolysaccharide (LPS)-induced changes in the activity of matrix metalloproteinases\\u000a (MMPs) and tissue plasminogen activator (tPA) in rat primary astrocytes. LPS stimulation increased MMP-9 and decreased tPA\\u000a activity in rat primary astrocytes. Co-treatment with a cAMP analog, dibutyryl-cAMP (db-cAMP), or the cAMP elevating beta-adrenergic\\u000a agonist, isoproterenol, concentration-dependently inhibited LPS-induced MMP-9 activity. In

Soon Young Lee; Hee Jin Kim; Woo Jong Lee; So Hyun Joo; Se-Jin Jeon; Ji Woon Kim; Hee Sun Kim; Seol-Heui Han; Jongmin Lee; Seung Hwa Park; Jae Hoon Cheong; Won-Ki Kim; Kwang Ho Ko; Chan Young Shin

2008-01-01

163

Effect of Ca2+, cyclic GMP, and cyclic AMP added to artificial solution perfusing lingual artery on frog gustatory nerve responses  

PubMed Central

The lingual artery of the bullfrog was perfused with artificial solution and the effects of Ca2+, Ca-channel blockers (MnCl2 and verapamil), cGMP, and cAMP added to the perfusing solution of the gustatory nerve responses were examined. The responses to chemical stimuli of group 1 (CaCl2, NaCl, distilled water, D-galactose, and L- threonine) applied to the tongue surface were greatly decreased by a decrease in Ca2+ concentration in the perfusing solution, suppressed by the Ca-channel blockers, enhanced by cGMP, and suppressed by cAMP. The responses to chemical stimuli of group 2 (quinine hydrochloride, theophylline, ethanol, and HCl) were practically not affected by a decrease in Ca2+ concentration, the Ca-channel blockers, cGMP, and cAMP. The responses to the stimuli of group 1 seem to be induced by Ca influx into a taste cell that is triggered by depolarization and modulated by the cyclic nucleotides in a taste cell. The responses to group 2 seem to be induced without accompanying Ca influx.

1982-01-01

164

ICAM-1Coupled Signaling Pathways in Astrocytes Converge to Cyclic AMP Response Element-Binding Protein Phosphorylation and TNF-a Secretion1  

Microsoft Academic Search

In the CNS, astrocytes play a key role in immunological and inflammatory responses through ICAM-1 expression, cytokine secretion (including TNF-a), and regulation of blood-brain barrier permeability. Because ICAM-1 transduces intracellular signals in lymphocytes and endothelial cells, we investigated in the present study ICAM-1-coupled signaling pathways in astrocytes. Using rat astrocytes in culture, we report that ICAM-1 binding by specific Abs

Sandrine Etienne-Manneville; Nathalie Chaverot; A. Donny Strosberg; Pierre-Olivier Couraud

165

Endothelins-induce cyclicAMP formation in the guinea-pig trachea through an ETA receptor- and cyclooxygenase-dependent mechanism.  

PubMed Central

1. The non-selective endothelin agonist, endothelin-1 (ET-1), and the selective ETB receptor agonist, sarafotoxin-S6c (SRTX-c), contracted guinea-pig isolated trachea in a concentration-dependent manner. The EC50 value for ET-1 (11 +/- 2.1 nM) was significantly higher than that of SRTX-c (3.2 +/- 0.21 nM) and the maximal developed tension due to SRTX-c was 42.8 +/- 2.3% higher than that produced by ET-1 (P < 0.05). 2. Pretreatment with the ETA antagonist, BQ-610, appreciably enhanced the developed tension due to ET-1 but not SRTX-c. Likewise, the cyclo-oxygenase inhibitor, indomethacin, markedly potentiated the contractile responses to ET-1, but not to SRTX-c. Combining BQ-610 with indomethacin was not more effective than either of them in augmenting ET-1-evoked tension. 3. ET-1 significantly increased cyclic AMP formation in the trachea in concentration- and time-dependent manners. A t1/2 value of 4.3 min, an EC50 value of 20 +/- 3 nM and a maximal cyclic AMP increment of 124% above the basal level, were obtained for ET-1. Similarly but less effectively, ET-3 (0.1 microM) increased cyclic AMP level (35 +/- 3.7% compared to 94 +/- 7.8% for the same concentration of ET-1). By contrast, SRTX-c did not alter the cyclicAMP level when applied in concentrations up to 1 microM. 4. Pre-incubation of the trachea with BQ-610 (1 microM) or indomethacin (1 microM) prevented cyclicAMP formation by either ET-1 or ET-3. 5. The results of the present study indicate a negative regulatory role mediated by the ETA receptor on the ETB-triggered mechanical response. This effect is likely to be mediated by activation of adenylate cyclase through a cyclo-oxygenase-dependent mechanism.

el-Mowafy, A. M.; Abou-Mohamed, G. A.

1996-01-01

166

Decoupling of horizontal cells in carp and turtle retinae by intracellular injection of cyclic AMP.  

PubMed Central

1. Horizontal cells are electrically coupled through gap junctions. This is a disadvantage in elucidating the membrane properties of the cells. In order to block gap junctions, adenosine 3',5'-cyclic monophosphate (cyclic AMP) or its analogues, dibutyryl cyclic AMP and 8-bromo cyclic AMP, were ionophoretically injected into horizontal cells of the carp or turtle retina. 2. Before injection of the chemicals the input resistance of the cell was so low as to be unmeasurable, because the applied current leaked through gap junctions. After injection, however, the input resistance was significantly increased. 3. After the injection dye-coupling between horizontal cells was not observed when examined by intracellular injection of Lucifer Yellow dye, supporting the idea that high concentrations of intracellular cyclic AMP block gap junctions. 4. In this situation responses to light delivered to the receptive field centre were increased in amplitude, while responses to light delivered to the receptive field surround were greatly diminished. 5. After injection horizontal cells were readily polarized by conventional intracellular current injection. The hyperpolarizing light responses in carp and turtle luminosity-type cells (H1 cells) could be reversed by depolarizing the horizontal cells, and the reversal potentials were estimated to be about 0 mV. In addition, the resistance increase which accompanied the hyperpolarizing light responses could be detected. 6. In turtle biphasic chromaticity-type horizontal cells (H2 cells), hyperpolarizing light responses to shorter wavelengths and depolarizing ones to longer wavelengths could be reversed by depolarizing the horizontal cells. Both responses have almost the same reversal potential at about 0 mV. The membrane resistance changes associated with light responses were also detected; the resistance increased during the hyperpolarizing response, while it decreased during the depolarizing response. These observations suggest that the ionic mechanisms of both responses are probably the same, irrespective of their polarities.

Miyachi, E; Murakami, M

1989-01-01

167

Phosphorylation of cyclic AMP-response element-binding protein (CREB) is influenced by melatonin treatment in pancreatic rat insulinoma ?-cells (INS-1).  

PubMed

The pineal hormone melatonin exerts its influence on the insulin secretion of pancreatic islets by a variety of signalling pathways. The purpose of the present study was to analyse the impact of melatonin on the phosphorylated transcription factor cAMP-response element-binding protein (pCREB). In pancreatic rat insulinoma ?-cells (INS-1), pCREB immunofluorescence intensities in cell nuclei using digitised confocal image analysis were measured to semi-quantify differences in the pCREB immunoreactivity (pCREB-ir) caused by different treatments. Increasing concentrations of forskolin or 3-isobutyl-1-methylxanthine (IBMX) resulted in a dose-dependent rise of the mean fluorescence intensity in pCREB-ir nuclear staining. Concomitant melatonin application significantly decreased pCREB-ir in INS-1 cells after 30-min, 1-hr and 3-hr treatment. The melatonin receptor antagonists luzindole and 4-phenyl-2-propionamidotetraline (4P-PDOT) completely abolished the pCREB phosphorylation-decreasing effect of melatonin, indicating that both melatonin receptor isoforms (MT(1) and MT(2)) are involved. In a transfected INS-1 cell line expressing the human MT(2) receptor, melatonin caused the greatest reduction in pCREB after IBMX treatment compared with nontransfected INS-1 cells, indicating a crucial influence of melatonin receptor density on pCREB regulation. Furthermore, the downregulation of pCREB by melatonin is concomitantly associated with a statistically significant downregulation of Camk2d transcript levels, as measured after 3 hr. In conclusion, the present study provides evidence that the phosphorylation level of CREB is modulated in pancreatic ?-cells by melatonin. Mediated via CREB, melatonin regulates the expression of genes that play an important functional role in the regulation of ?-cell signalling pathways. PMID:22616931

Bazwinsky-Wutschke, Ivonne; Wolgast, Sabine; Mühlbauer, Eckhard; Albrecht, Elke; Peschke, Elmar

2012-05-23

168

Cyclic AMP is one of the intracellular signals during the mating of Chlamydomonas eugametos  

Microsoft Academic Search

Chlamydomonas eugametos gametes of opposite mating type make cell-cell contact via their flagellar surfaces. This contact triggers an increase in the intracellular level of cyclic AMP (cAMP) and several cellular responses which are necessary for cell fusion. Here, we show that wheat-germ agglutinin, which binds to the flagellar surface and induces all mating responses, also increased the intracellular cAMP level.

Ron Kooijman; Piet de Wildt; Wies van den Briel; Shu-hui Tan; Alan Musgrave; Herman van den Ende

1990-01-01

169

Post-receptor modulation of the effects of cyclic AMP in isolated cardiac myocytes  

Microsoft Academic Search

The actions of cyclic AMP are subject to several levels of post-receptor modulation in cardiac tissue. Isoproterenol and prostaglandin E1 both stimulate cAMP accumulation, but only isoproterenol causes activation of particulate cAMP-dependent protein kinase, leading to activation of phosphorylase kinase and glycogen phosphorylase, and inhibition of glycogen synthase. Through the use of isolated, adult ventricular myocytes, we have determined that

Donald C. Bode; Laurence L. Brunton

1988-01-01

170

Effect of Dihydroergotoxine on Cyclic-AMP-Generating Systems in Rat Cerebral Cortex Slices  

Microsoft Academic Search

In slices of rat cerebral cortex, cyclic-AMP formation is stimulated in response to added noradrenaline (NA), isoproterenol (ISP) or adenosine. The effect of ISP could be antagonized only by the selective ?-adrenoceptor-blocking agent pindolol, whereas the stimulating effect of NA could be antagonized by both ?- and ?-adrenoceptor-blocking agents. Dihydroergotoxine (DHET) at low concentrations (10-8M) antagonized the stimulating effect of

R. Markstein; H. Wagner

1978-01-01

171

Effect of Hydrogen Sulfide on Cyclic AMP Production in Isolated Bovine and Porcine Neural Retinae  

Microsoft Academic Search

Hydrogen sulfide (H2S) has been reported to exert pharmacological effects on neural and non-neural tissues from several mammalian species. In\\u000a the present study, we examined the role of the intracellular messenger, cyclic AMP in retinal response to H2S donors, sodium hydrosulfide (NaHS) and sodium sulfide (Na2S) in cows and pigs. Isolated bovine and porcine neural retinae were incubated in oxygenated

Ya Fatou Njie-Mbye; Odelia Y. N. Bongmba; Chinwe C. Onyema; Abhishek Chitnis; Madhura Kulkarni; Catherine A. Opere; Angela M. LeDay; Sunny E. Ohia

2010-01-01

172

Transcription activation at the Escherichia coli melAB promoter: the role of MelR and the cyclic AMP receptor protein  

Microsoft Academic Search

Summary MelR is a melibiose-triggered transcription activator that belongs to the AraC family of transcription factors. Using purified Escherichia coli RNA polymerase and a cloned DNA fragment carrying the entire melibiose operon intergenic region, we have demonstrated in vitro open complex formation and activation of tran- scription initiation at the melAB promoter. This acti- vation is dependent on MelR and

Tamara A. Belyaeva; Joseph T. Wade; Christine L. Webster; Victoria J. Howard; Mark S. Thomas; Eva I. Hyde; Stephen J. W. Busby

2000-01-01

173

Regulation of Phosphorylation of a Specific Protein in Toad-Bladder Membrane by Antidiuretic Hormone and Cyclic AMP, and Its Possible Relationship to Membrane Permeability Changes  

PubMed Central

Phosphorylation of a specific protein was decreased in intact toad bladders by exposure to either antidiuretic hormone or monobutyryl cyclic AMP. The decrease in phosphorylation caused by these agents preceded the change in electrical potential difference (an indicator of the rate of sodium ion transport) observed in response to the same compounds. The addition of cyclic AMP to homogenates of toad bladder led to a decrease in phosphorylation of the same, or a similar, protein. In subcellular fractionation studies, the effect of cyclic AMP on the phosphorylation of this protein was observed in those fractions rich in membrane fragments, but not in the nuclear or cell-sap fractions. These and other results are compatible with the possibility that the regulation by vasopressin and cyclic AMP of sodium and/or water transport in toad bladder may be mediated through regulation of the phosphorylation of this specific protein. Images

DeLorenzo, Robert J.; Walton, Kenneth G.; Curran, Peter F.; Greengard, Paul

1973-01-01

174

? and k opiate receptors in primary astroglial cultures part II: Receptor sets in cultures from various brain regions and interactions with ß-receptor activated cyclic AMP  

Microsoft Academic Search

In a previous paper, and opiate receptors were shown to be co-localized on the same cell in enriched primary cultures of astroglia from neonatal rat cerebral cortex. Activation of the receptors inhibited adenylate cyclase. In this work, the presence of opiate receptors was investigated in astroglial primary cultures from neonatal rat striatum and brain stem. Cyclic adenosine 3, 5-monophosphate accumulation

Peter S. Eriksson; Elisabeth Hansson; Lars Rönnbäck

1992-01-01

175

Cyclic AMP post-transcriptionally regulates the biosynthesis of a major bacterial autoinducer to modulate the cell density required to activate quorum sensing  

PubMed Central

In Vibrio cholerae, expression of the quorum sensing regulator HapR is induced by the accumulation of a major autoinducer synthesized by the activity of CqsA. Here we show that the cAMP-cAMP receptor protein complex regulates cqsA expression at the post-transcriptional level. This conclusion is supported by the analysis of cqsA-lacZ fusions, the ectopic expression of cqsA in ?crp mutants and by Northern blot analysis showing that cqsA mRNA is unstable in ?crp and ?cya (adenylate cyclase) mutants. Addition of cAMP to the culture of a ?cya mutant restored cqsA mRNA stability and CAI-1 production. Lowering intracellular cAMP levels by addition of D-glucose increased the cell density required to activate HapR. These results indicate that cAMP acts as a quorum modulator.

Liang, Weili; Sultan, Syed Zafar; Silva, Anisia J.; Benitez, Jorge A.

2008-01-01

176

Temporal coupling of cyclic AMP and Ca2+/CaM-stimulated adenylyl cyclase to the circadian clock in chick retinal photoreceptor cells  

PubMed Central

Cyclic AMP signaling pathways play crucial roles in photoreceptor cells and other retinal cell types. Previous studies demonstrated a circadian rhythm of cyclic AMP level in chick photoreceptor cell cultures that drives the rhythm of activity of the melatonin synthesizing enzyme arylalkylamine N-acetyltransferase (Ivanova and Iuvone, 2003a) and the rhythm of affinity of the cyclic nucleotide-gated channel for cyclic GMP (Ko et al., 2004). Here we report that the photoreceptor circadian clock generates a rhythm in Ca2+/calmodulin-stimulated adenylyl cyclase activity, which accounts for the temporal changes in the cyclic AMP levels in the photoreceptors. The circadian rhythm of cyclic AMP in photoreceptor cell cultures is abolished by treatment with the L-type Ca2+ channel antagonist nitrendipine, while the Ca2+ channel agonist, Bay K 8644, increased cyclic AMP levels with continued circadian rhythmicity in constant darkness. These results indicate that the circadian rhythm of cyclic AMP is dependent, in part, on Ca2+ influx. Photoreceptor cell cultures exhibit a circadian rhythm in Ca2+/calmodulin-stimulated adenylyl cyclase enzyme activity with high levels at night and low levels during the day, correlating with the temporal changes of cyclic AMP in these cells. Both of the Ca2+/calmodulin-stimulated adenylyl cyclase genes, type 1 and type 8 (Adcy1 and Adcy8), displayed significant daily rhythms of mRNA expression under a light-dark cycle, but only the Adcy1 transcript rhythm persisted in constant darkness. Similar rhythms of Adcy1 mRNA level and Ca2+/calmodulin-stimulated adenylyl cyclase activity were observed in retinas of 2 week old chickens. These results indicate that a circadian clock controls the expression of Adcy1 mRNA and Ca2+/calmodulin-stimulated adenylyl cyclase activity; and calcium influx into these cells gates the circadian rhythm of cyclic AMP, a key component in the regulation of photoreceptor function.

Chaurasia, Shyam S.; Haque, Rashidul; Pozdeyev, Nikita; Jackson, Chad R.; Iuvone, P. Michael

2009-01-01

177

The Transcriptional Activity of NF-?B Is Regulated by the I?B-Associated PKAc Subunit through a Cyclic AMP–Independent Mechanism  

Microsoft Academic Search

Stimulation of cells with inducers of NF-?B such as LPS and IL-1 leads to the degradation of I?B-? and I?B-? proteins and translocation of NF-?B to the nucleus. We now demonstrate that, besides the physical partitioning of inactive NF-?B to the cytosol, the transcriptional activity of NF-?B is regulated through phosphorylation of NF-?B p65 by protein kinase A (PKA). The

Haihong Zhong; Helena SuYang; Hediye Erdjument-Bromage; Paul Tempst; Sankar Ghosh

1997-01-01

178

A Fluorescence-Based High-Throughput Assay for the Discovery of Exchange Protein Directly Activated by Cyclic AMP (EPAC) Antagonists  

PubMed Central

Background The discovery, more than ten years ago, of exchange proteins directly activated by cAMP (EPAC) as a new family of intracellular cAMP receptors revolutionized the cAMP signaling research field. Extensive studies have revealed that the cAMP signaling network is much more complex and dynamic as many cAMP-related cellular processes, previously thought to be controlled by protein kinase A, are found to be also mediated by EPAC proteins. Although there have been many important discoveries in the roles of EPACs greater understanding of their physiological function in cAMP-mediated signaling is impeded by the absence of EPAC-specific antagonist. Methodology/Principal Findings To overcome this deficit, we have developed a fluorescence-based high throughput assay for screening EPAC specific antagonists. Our assay is highly reproducible and simple to perform using the “mix and measure” format. A pilot screening using the NCI-DTP diversity set library led to the identification of small chemical compounds capable of specifically inhibiting cAMP-induced EPAC activation while not affecting PKA activity. Conclusions/Significance Our study establishes a robust high throughput screening assay that can be effectively applied for the discovery of EPAC-specific antagonists, which may provide valuable pharmacological tools for elucidating the biological functions of EPAC and for promoting an understanding of disease mechanisms related to EPAC/cAMP signaling.

Tsalkova, Tamara; Mei, Fang C.; Cheng, Xiaodong

2012-01-01

179

Integration host factor and cyclic AMP receptor protein are required for TyrR-mediated activation of tpl in Citrobacter freundii.  

PubMed

The tpl gene of Citrobacter freundii encodes an enzyme that catalyzes the conversion of L-tyrosine to phenol, pyruvate, and ammonia. This gene is known to be positively regulated by TyrR. The amplitude of regulation attributable to this transcription factor is at least 20-fold. Three TyrR binding sites, designated boxes A, B, and C, centered at coordinates -272.5, -158.5, and -49.5, respectively, were identified in the upstream region of the tpl promoter. The results of mutational experiments suggest that TyrR binds in cooperative fashion to these sites. The nonavailability of any TyrR site impairs transcription. Full TyrR-mediated activation of tpl required integration host factor (IHF) and the cAMP receptor protein (CRP). By DNase I footprinting, it was shown that the IHF binding site is centered at coordinate -85 and that there are CRP binding sites centered at coordinates -220 and -250. Mutational alteration of the IHF binding site reduced the efficiency of the tpl promoter by at least eightfold. The proposed roles of CRP and IHF are to introduce bends into tpl promoter DNA between boxes A and B or B and C. Multimeric TyrR dimers were demonstrated by a chemical cross-linking method. The formation of hexameric TyrR increased when tpl DNA was present. The participation of both IHF and CRP in the activation of the tpl promoter suggests that molecular mechanisms quite different from those that affect other TyrR-activated promoters apply to this system. A model wherein TyrR, IHF, and CRP collaborate to regulate the expression of the tpl promoter is presented. PMID:9829925

Bai, Q; Somerville, R L

1998-12-01

180

Characterization of histamine receptors mediating the stimulation of cyclic AMP accumulation in rabbit cerebral cortical slices.  

PubMed Central

The characteristics of histamine-stimulated adenosine 3':5'-cyclic monophosphate (cyclic AMP) accumulation in slices of rabbit cerebral cortex have been investigated. The selective H2-receptor antagonists, cimetidine, tiotidine, metiamide and ranitidine appeared to antagonize the stimulation of cyclic AMP accumulation elicited by histamine in a competitive manner consistent with an interaction with histamine H2-receptors. The H1-receptor antagonist mepyramine (0.8 microM) produced only a weak inhibition of the response to histamine. The inhibition appeared to be non-competitive producing a decrease in the maximal response with little effect on the EC50 value. The specific H2-receptor agonist, impromidine, produced a maximum response of only 31 +/- 2% of that obtained with histamine. Studies with histamine and impromidine in combination indicated that impromidine was not acting as a partial agonist. 2-Thiazolylethylamine, a selective H1-agonist, produced only a weak response (EC50 approximately 1mM) yielding a relative potency with respect to histamine (= 100) of 2.5. In the presence of a supramaximal concentration of impromidine, histamine and 2-thiazolylethylamine further elevated the response to impromidine. In these conditions the relative potency of 2-thiazolylethylamine was increased to 59 (histamine = 100), a value which was comparable with that reported for H1-receptor-mediated contractions of guinea-pig ileum. The H1-receptor antagonists mepyramine, promethazine, triprolidine and chlorpheniramine competitively antagonized the potentiation of impromidine-stimulated cyclic AMP accumulation elicited by histamine and 2-thiazolylethylamine in rabbit cerebral cortex without affecting the response to impromidine alone. (+)-Chlorpheniramine was some 150 fold more potent than the (-)-isomer in this respect. Histamine and adenosine in combination had a much greater than additive effect on the accumulation of cyclic AMP in rabbit cerebral cortical slices. The potentiation of the adenosine response could be partially but not completely antagonized by either cimetidine or mepyramine. In the presence of H2-receptor blockade with 0.02 mM tiotidine, histamine elicited a significant potentiation (EC50 44 microM) of the response to adenosine. This response was antagonized competitively by mepyramine yielding a KB value of 0.05 microM similar to that obtained from inhibition of the potentiation of impromidine-stimulated accumulation of cyclic AMP (0.02 microM). These results suggest that there are two components in the response to histamine in rabbit cerebral cortical slices.(ABSTRACT TRUNCATED AT 400 WORDS)

Al-Gadi, M.; Hill, S. J.

1985-01-01

181

The Cyclic AMP-Dependent Protein Kinase A Network Regulates Development and Virulence in Aspergillus fumigatus  

Microsoft Academic Search

Aspergillus fumigatus is an important pathogen of immunocompromised hosts, causing pneumonia and invasive disseminated disease with high mortality. To determine the importance of the cyclic AMP (cAMP) signaling pathway for virulence, the pkaC1 gene encoding a protein kinase A (PKA) catalytic subunit was cloned and characterized. Deletion of pkaC1 led to reduced conidiation and growth. PKA activity was not detectable

Burghard Liebmann; Meike Muller; Armin Braun; Axel A. Brakhage

2004-01-01

182

Role of cyclic AMP in the release of noradrenaline from isolated rat atria  

Microsoft Academic Search

The possible role of cyclic AMP (cAMP) on tritium overflow evoked by stimulation of the cardioaccelerant nerves was studied in rat atria preincubated with [3H]-noradrenaline. Addition of the activator of adenylate cyclase forskolin (1 µmol\\/l), or of the phosphodiesterase inhibitor 3-isobutyl-l-methylxanthine (IBMx, 100 µmol\\/l), did not affect both basal and evoked overflow. However, in the presence of the a2-adrenoceptor antagonist

Marcelo G. Kazanietz; Maria Amelia Enero

1992-01-01

183

Opposite effects of cyclic GMP and cyclic AMP on Ca2+ current in single heart cells  

Microsoft Academic Search

The slow inward Ca2+ current, ICa, is fundamental in the initiation of cardiac contraction and neurohormonal regulation of cardiac function1. It is increased by beta-adrenergic agonists, which stimulate synthesis of cyclic AMP (cAMP) and cAMP-dependent phosphorylation2-4. The neurotransmitter acetylcholine reduces ICa5-7 by an unknown mechanism8,9. There is strong evidence that acetylcholine reduces ICa by decreasing adenylate cyclase activity7, but cGMP

H. Criss Hartzell; Rodolphe Fischmeister

1986-01-01

184

Activation of protein kinase C inhibits prostaglandin- and potentiates adenosine receptor-stimulated accumulation of cyclic AMP in a human T-cell leukemia line.  

PubMed

Accumulation of cAMP in the human T-cell leukemia cell line Jurkat was stimulated by the adenosine analogue 5'-N-ethylcarboxamidoadenosine (NECA) and by prostaglandin E2 (PGE2). Addition of two phorbol esters, PDiBu and TPA, markedly enhanced the NECA-stimulated accumulation of cAMP whereas the PGE2-stimulated cAMP accumulation was substantially reduced. The non-tumor-promoting phorbol ester, 4 alpha-PDD, had no effect on either NECA- or PGE2-stimulated cAMP accumulation. The ability of PDiBu to inhibit the effect of PGE2 and to stimulate the effect of NECA remained in the presence a low concentration of forskolin (0.3 microM), which per se increased both NECA- and PGE2-stimulated cAMP accumulation. Our results suggest that the effect of PK-C-activating drugs on receptor-mediated cAMP accumulation is entirely dependent on which receptor is being stimulated. PMID:3038616

Nordstedt, C; Jondal, M; Fredholm, B B

1987-08-10

185

From Drought Sensing to Developmental Control: Evolution of Cyclic AMP Signaling in Social Amoebas  

PubMed Central

Amoebas and other protists commonly encyst when faced with environmental stress. Although little is known of the signaling pathways that mediate encystation, the analogous process of spore formation in dictyostelid social amoebas is better understood. In Dictyostelium discoideum, secreted cyclic AMP (cAMP) mediates the aggregation of starving amoebas and induces the differentiation of prespore cells. Intracellular cAMP acting on cAMP-dependent protein kinase (PKA) triggers the maturation of spores and prevents their germination under the prevalent conditions of high osmolality in the spore head. The osmolyte-activated adenylate cyclase, ACG, produces cAMP for prespore differentiation and inhibition of spore germination. To retrace the origin of ACG function, we investigated ACG gene conservation and function in species that span the dictyostelid phylogeny. ACG genes, osmolyte-activated ACG activity, and osmoregulation of spore germination were detected in species that represent the 4 major groups of Dictyostelia. Unlike the derived species D. discoideum, many basal Dictyostelia have retained the ancestral mechanism of encystation from solitary amoebas. In these species and in solitary amoebas, encystation is independently triggered by starvation or by high osmolality. Osmolyte-induced encystation was accompanied by an increase in cAMP and prevented by inhibition of PKA, indicating that ACG and PKA activation mediate this response. We propose that high osmolality signals drought in soil amoebas and that developmental cAMP signaling in the Dictyostelia has evolved from this stress response.

Ritchie, Allyson V.; van Es, Saskia; Fouquet, Celine

2008-01-01

186

Combined Effects of Insulin and Dexamethasone on Cyclic AMP Phosphodiesterase 3 and Glycogen Metabolism in Cultured Rat Hepatocytes  

Microsoft Academic Search

Primary cultures of rat hepatocytes were used to study the combined effects of insulin and dexamethasone on cyclic AMP phosphodiesterase 3 (PDE 3) and glycogen metabolism. PDE activity was measured in extracts obtained by hypotonic shock treatment of the particulate fraction from cultured hepatocytes. PDE 3 was identified by inhibition with ICI 118233, Western blotting, immunoprecipitation of the activity with

Thomas Hermsdorf; Dietrich Dettmer

1998-01-01

187

Prostaglandin A1 metabolism and inhibition of cyclic AMP extrusion by avian erythrocytes  

SciTech Connect

Prostaglandins (PG) inhibit active cyclic AMP export from pigeon red cells, PGA1 and PGA2 most potently. To probe the mechanism of this action of PGA1, the authors have studied the interaction of (TH)PGA1 with suspensions of pigeon red cells. The interaction of PGA1 with pigeon red cells is a multistep process of uptake, metabolism, and secretion. (TH) PGA1 rapidly enters red cells and is promptly metabolized to a compound(s) that remains in the aqueous layer after ethylacetate extraction. The glutathione-depleting agent, diamide, inhibits formation of the PGA1 metabolite. The red cells secrete the polar metabolite of PGA1 by a saturable mechanism that lowered temperatures inhibit. Because uptake and metabolism progress with much greater rates than metabolite secretion, red cells transiently concentrate the polar compound intracellularly. Onset and reversal of inhibition of cyclic AMP export by PGA1 coincide with accumulation and secretion of PGA1 metabolite, suggesting that the polar metabolite acts at an intracellular site to inhibit cyclic AMP efflux.

Heasley, L.E.; Brunton, L.L.

1985-09-25

188

The Cyclic AMP Phenotype of Fragile X and Autism  

PubMed Central

Cyclic AMP (cAMP) is a second messenger involved in many processes including mnemonic processing and anxiety. Memory deficits and anxiety are noted in the phenotype of fragile X (FX), the most common heritable cause of mental retardation and autism. Here we review reported observations of altered cAMP cascade function in FX and autism. Cyclic AMP is a potentially useful biochemical marker to distinguish autism comorbid with FX from autism per se and the cAMP cascade may be a viable therapeutic target for both FX and autism.

Kelley, Daniel J; Bhattacharyya, Anita; Lahvis, Garet P; Yin, Jerry CP; Malter, Jim; Davidson, Richard J

2008-01-01

189

Rasd1 Modulates the Coactivator Function of NonO in the Cyclic AMP Pathway  

PubMed Central

All living organisms exhibit autonomous daily physiological and behavioural rhythms to help them synchronize with the environment. Entrainment of circadian rhythm is achieved via activation of cyclic AMP (cAMP) and mitogen-activated protein kinase signaling pathways. NonO (p54nrb) is a multifunctional protein involved in transcriptional activation of the cAMP pathway and is involved in circadian rhythm control. Rasd1 is a monomeric G protein implicated to play a pivotal role in potentiating both photic and nonphotic responses of the circadian rhythm. In this study, we have identified and validated NonO as an interacting partner of Rasd1 via affinity pulldown, co-immunoprecipitation and indirect immunofluorescence studies. The GTP-hydrolysis activity of Rasd1 is required for the functional interaction. Functional interaction of Rasd1-NonO in the cAMP pathway was investigated via reporter gene assays, chromatin immunoprecipitation and gene knockdown. We showed that Rasd1 and NonO interact at the CRE-site of specific target genes. These findings reveal a novel mechanism by which the coregulator activity of NonO can be modulated.

Ong, Shufen Angeline; Tan, Jen Jen; Tew, Wai Loon; Chen, Ken-Shiung

2011-01-01

190

Stimulation of osmotic water flow in toad bladder by prostaglandin E1. Evidence for different compartments of cyclic AMP.  

PubMed Central

The effect of prostaglandin E1 (PGE1) on osmotic water flow across toad bladder and cyclic AMP content of the mucosal epithelial cells has been determined under basal conditions and in the presence of either theophylline or antidiuretic hormone (ADH); Under basal conditions and with PGE1 concentrations from 10(-8) to 10(-5) M no evidence of stimulation of water flow was observed, and with 10(-7) M PGE1 a significant inhibition was foundmcyclic AMP content under control conditions was 8 pmol/mg protein. It was 9 at 10(-8) M PGE1, 13 at 10(-7) M, 16 at 10(-6) M, and 23 at 10(-5) M. In the presence of theophylline, 10(-8) and 10(-7) M PGE1 inhibited the theophylline-induced water flow as expected. In contrast, 10(-6) and 10(-5) M PGE1 enhanced the rate of water flow. Theophylline increased cyclic AMP content from 8 to 18 pmol/mg protein. PGE1 in the presence of theophylline caused marked increases in cyclic AMP content; The content was 23 at 10(-7) M, 41 at 10(-6) M, and 130 at 10(-5) M; Thus PGE1 stimulates theophylline-induced water flow at cyclic AMP concentrations somewhere between 23 and 41 pmol/mg. Further evidence along these lines was obtained from experiments in which the effects of PGE1 on ADH-induced water flow were studied. Inhibitory effects of PGE1 were not observed at concentrations of PGE1 which raised the level of intracellular cyclic AMP to 30 pmol/mg protein or higher. These results were obtained despite the fact that all four concentrations of PGE1 tested were found capable of inhibiting ADH-induced water flow under appropriate conditions or, in other words, were inhibiting the adenylate cyclase controlling water flow, Thus the increase in cyclic AMP content in response to PGE1 is not derived from this enzyme. Thus the stimulation of water flow by PGE1 in the presence of theophylline is thought to be caused by cyclic AMP spilling over from one compartment to the water flow compartment. No evidence was obtained to directly suggest spillover into the sodium transport compartment. Furthermore evidence is discussed to suggest that most of the cyclic AMP generated in the tissue does not originate from the enzyme controlling sodium transport. As cyclic AMP-stimulated water flow and sodium transport are thought to occur in one cell type, the granular cells, distinct pools of cyclic AMP are thought to be present in one and the same cell type. Thus one pool controls water flow and one controls sodium transport. With high concentrations of PGE1 in the presence of theophylline or high concentrations of ADH, the adenylate cyclase responsible for water flow is inhibited; However, PGE1 can stimulate a tissue adenylate cyclase to sufficiently high levels that cyclic AMP spills over into the "water flow compartment" and thus stimulates water flow. Images

Flores, J; Witkum, P A; Beckman, B; Sharp, G W

1975-01-01

191

Induction of ketogenesis and fatty acid oxidation by glucagon and cyclic AMP in cultured hepatocytes from rabbit fetuses. Evidence for a decreased sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition after glucagon or cyclic AMP treatment.  

PubMed Central

The effects of pancreatic hormones and cyclic AMP on the induction of ketogenesis and long-chain fatty acid oxidation were studied in primary cultures of hepatocytes from fetal and newborn rabbits. Hepatocytes were cultivated during 4 days in the presence of glucagon (10(-6) M), forskolin (2 x 10(-5) M), dibutyryl cyclic AMP (10(-4) M), 8-bromo cyclic AMP (10(-4) M) or insulin (10(-7) M). Ketogenesis and fatty acid metabolism were measured using [1-14C]oleate (0.5 mM). In hepatocytes from fetuses at term, the rate of ketogenesis remained very low during the 4 days of culture. In hepatocytes from 24-h-old newborn, the rate of ketogenesis was high during the first 48 h of culture and then rapidly decreased to reach a low value similar to that measured in cultured hepatocytes from term fetuses. A 48 h exposure to glucagon, forskolin or cyclic AMP derivatives is necessary to induce ketone body production in cultured fetal hepatocytes at a rate similar to that found in cultured hepatocytes from newborn rabbits. In fetal liver cells, the induction of ketogenesis by glucagon or cyclic AMP results from changes in the partitioning of long-chain fatty acid from esterification towards oxidation. Indeed, glucagon, forskolin and cyclic AMP enhance oleate oxidation (basal, 12.7 +/- 1.6; glucagon, 50.0 +/- 5.5; forskolin, 70.6 +/- 5.4; cyclic AMP, 77.5 +/- 3.4% of oleate metabolized) at the expense of oleate esterification. In cultured fetal hepatocytes, the rate of fatty acid oxidation in the presence of cyclic AMP is similar to the rate of oleate oxidation present at the time of plating (85.1 +/- 2.6% of oleate metabolized) in newborn rabbit hepatocytes. In hepatocytes from term fetuses, the presence of insulin antagonizes in a dose-dependent fashion the glucagon-induced oleate oxidation. Neither glucagon nor cyclic AMP affect the activity of carnitine palmitoyltransferase I (CPT I). The malonyl-CoA concentration inducing 50% inhibition of CPT I (IC50) is 14-fold higher in mitochondria isolated from cultured newborn hepatocytes (0.95 microM) compared with fetal hepatocytes (0.07 microM), indicating that the sensitivity of CPT I decreases markedly in the first 24 h after birth. The addition of glucagon or cyclic AMP into cultured fetal hepatocytes decreased by 80% and 90% respectively the sensitivity of CPT I to malonyl-CoA inhibition. In the presence of cyclic AMP, the sensitivity of CPT I to malonyl-CoA inhibition in cultured fetal hepatocytes is very similar to that measured in cultured hepatocytes from 24-h-old newborns.

Pegorier, J P; Garcia-Garcia, M V; Prip-Buus, C; Duee, P H; Kohl, C; Girard, J

1989-01-01

192

Independent cyclic AMP and E1A induction of adenovirus early region 4 expression.  

PubMed Central

A cellular transcription factor, ATF, binds to a repeated element in the adenovirus early region 4 (E4) promoter. ATF also binds to other viral early promoter regions and to the cyclic AMP (cAMP) response elements of cellular genes. In this report, we demonstrate that a single ATF-binding site located immediately upstream of the E4 TATA box, between -62 and -46, mediates induction of E4 transcription by 8-bromoadenosine-3',5-cyclic monophosphate or cholera toxin in the human hepatoma cell line HepG2 and rat pheochromocytoma cell line PC12. Different ATF-binding sites in the E4 control region independently conferred cAMP inducibility on the simian virus 40 early promoter in PC12 cells. Induction of E4 expression by cAMP was also observed in virus-infected HepG2 cells. Other viral early promoter regions that contain ATF-binding sites (E1A and E2A) were also induced by cAMP in infected cells. E4 expression was activated by the E1A 13S mRNA products in HepG2 cells. E1A trans activation appears to be distinct from the cAMP response. Images

Leza, M A; Hearing, P

1989-01-01

193

Sensitization and dishabituation of swim induction in the leech Hirudo medicinalis: role of serotonin and cyclic AMP  

Microsoft Academic Search

In this paper the role of serotonin (5HT) and cyclic AMP (cAMP) in sensitization and dishabituation of swim induction (SI) has been investigated in the leech Hirudo medicinalis. Electrical stimulation of the body wall evokes swimming activity with a constant latency. In animals with a disconnection between head ganglion and segmental ganglia, repetitive stimulation induces habituation of swimming whereas brushing

Maria Luisa Zaccardi; Giovanna Traina; Enrico Cataldo; Marcello Brunelli

2004-01-01

194

Adenosine induces cyclic-AMP formation and inhibits endothelin-1 production/secretion in guinea-pig tracheal epithelial cells through A2B adenosine receptors  

PubMed Central

The adenosine receptor subtype mediating adenosine 3??:?5?-cyclic monophosphate (cyclic AMP) formation and the effect of its activation on endothelin-1 (ET-1) secretion were studied in primary cultures of tracheal epithelial cells. Adenosine analogues showed the following rank order of potency (pD2 value) and intrinsic activity on the generation of cyclic AMP by tracheal epithelial cells: 5?-N-ethylcarboxyamidoadenosine (NECA, A1/A2A/A2B, pD2: 5.44±0.16)>adenosine (ADO, non selective, pD2: 4.99±0.09; 71±9% of NECA response) ?2-Cl-adenosine (2CADO, non selective, pD2: 4.72±0.14; 65±9% of NECA response)>>>CGS21680 (A2A; inactive at up to 100??M). Cyclic AMP formation stimulated by NECA in guinea-pig tracheal epithelial cells was inhibited by adenosine receptor antagonist with the following order of apparent affinity (pA2 value): Xanthine amine congeners (XAC, A2A/A2B, 7.89±0.22)>CGS15943 (A2A/A2B, 7.24±0.26)>ZM241385 (A2A, 6.69±0.14)>DPCPX (A1, 6.51±0.14)>3n-propylxanthine (weak A2B, 4.30±0.10). This rank order of potency is typical for A2B-adenosine receptor. Adenosine decreased basal and LPS-stimulated irET production in a concentration-dependent manner. Moreover, NECA but not CGS21680 inhibited LPS-induced irET production. The inhibitory effect of NECA on LPS-induced irET production was reversed by XAC (pA2=8.84±0.12) and DPCPX (pA2=8.10±0.22). These results suggested that adenosine increased cyclic AMP formation and inhibited irET production/secretion by guinea-pig tracheal epithelial cells through the activation of a functional adenosine receptor that is most likely the A2B subtype. This adenosine receptor may be involved in the regulation of the level of ET-1 production/secretion by guinea-pig tracheal epithelial cells in physiological as well as in pathophysiological conditions.

Pelletier, Stephane; Dube, Jean; Villeneuve, Annie; Gobeil, Fernand; Bernier, Sylvie G; Battistini, Bruno; Guillemette, Gaetan; Sirois, Pierre

2000-01-01

195

Farnesol and Cyclic AMP Signaling Effects on the Hypha-to-Yeast Transition in Candida albicans  

PubMed Central

Candida albicans, a fungal pathogen of humans, regulates its morphology in response to many environmental cues and this morphological plasticity contributes to virulence. Farnesol, an autoregulatory molecule produced by C. albicans, inhibits the induction of hyphal growth by inhibiting adenylate cyclase (Cyr1). The role of farnesol and Cyr1 in controlling the maintenance of hyphal growth has been less clear. Here, we demonstrate that preformed hyphae transition to growth as yeast in response to farnesol and that strains with increased cyclic AMP (cAMP) signaling exhibit more resistance to farnesol. Exogenous farnesol did not induce the hypha-to-yeast transition in mutants lacking the Tup1 or Nrg1 transcriptional repressors in embedded conditions. Although body temperature is not required for embedded hyphal growth, we found that the effect of farnesol on the hypha-to-yeast transition varies inversely with temperature. Our model of Cyr1 activity being required for filamentation is also supported by our liquid assay data, which show increased yeast formation when preformed filaments are treated with farnesol. Together, these data suggest that farnesol can modulate morphology in preformed hyphal cells and that the repression of hyphal growth maintenance likely occurs through the inhibition of cAMP signaling.

Lindsay, Allia K.; Deveau, Aurelie; Piispanen, Amy E.

2012-01-01

196

Cell-specific cyclic AMP-mediated induction of the PDGF receptor.  

PubMed Central

Cyclic AMP (cAMP) cooperates with a wide variety of polypeptide growth factors to synergistically stimulate the proliferation of many vertebrate cell types. However, the cellular mechanisms underlying these cooperative interactions are for the most part unknown. We have identified one such mechanism by observing that (i) cultured rat Schwann cells proliferate in response to platelet-derived growth factor (PDGF) only if simultaneously cultured in the presence of agents that elevate intracellular cAMP and (ii) this unmasked PDGF response is accounted for by a dramatic cAMP-mediated induction of PDGF receptor mRNA and protein. cAMP-mediated induction of the PDGF receptor results in enhanced, ligand dependent receptor autophosphorylation, and in enhanced PDGF activation of c-fos gene expression. In addition, this induction is unique to those cells, such as Schwann cells, for which cAMP is itself mitogenic. These results indicate that the synergistic proliferative effect obtained from the combination of cAMP and polypeptide growth factors may in large result from the cAMP-mediated induction of growth factor receptors. Images Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6.

Weinmaster, G; Lemke, G

1990-01-01

197

Farnesol and cyclic AMP signaling effects on the hypha-to-yeast transition in Candida albicans.  

PubMed

Candida albicans, a fungal pathogen of humans, regulates its morphology in response to many environmental cues and this morphological plasticity contributes to virulence. Farnesol, an autoregulatory molecule produced by C. albicans, inhibits the induction of hyphal growth by inhibiting adenylate cyclase (Cyr1). The role of farnesol and Cyr1 in controlling the maintenance of hyphal growth has been less clear. Here, we demonstrate that preformed hyphae transition to growth as yeast in response to farnesol and that strains with increased cyclic AMP (cAMP) signaling exhibit more resistance to farnesol. Exogenous farnesol did not induce the hypha-to-yeast transition in mutants lacking the Tup1 or Nrg1 transcriptional repressors in embedded conditions. Although body temperature is not required for embedded hyphal growth, we found that the effect of farnesol on the hypha-to-yeast transition varies inversely with temperature. Our model of Cyr1 activity being required for filamentation is also supported by our liquid assay data, which show increased yeast formation when preformed filaments are treated with farnesol. Together, these data suggest that farnesol can modulate morphology in preformed hyphal cells and that the repression of hyphal growth maintenance likely occurs through the inhibition of cAMP signaling. PMID:22886999

Lindsay, Allia K; Deveau, Aurélie; Piispanen, Amy E; Hogan, Deborah A

2012-08-10

198

Protective effect of cyclic AMP against cisplatin-induced nephrotoxicity  

Microsoft Academic Search

We reported earlier that reactive oxygen species are implicated in necrotic injury induced by a transient exposure of cultured renal tubular cells to a high concentration of cisplatin but not in apoptosis occurring after continuous exposure to a low concentration of cisplatin. We report here the protective effect of cyclic AMP against cisplatin-induced necrosis in cultured renal tubular cells as

Kazuto Mishima; Anri Baba; Misaki Matsuo; Yoshinori Itoh; Ryozo Oishi

2006-01-01

199

Transcription of the yeast mitochondrial genome requires cyclic AMP  

Microsoft Academic Search

Using various mutant strains and nutritional manipulations, we investigated a potential role for cyclic AMP (cAMP) in the regulation of mitochondrial (mt) gene expression in the yeast Saccharomyces cerevisiae. In RAS mutants known to have either abnormally low or high cellular levels of this nucleotide, we show that both mt transcription rate and overall mt transcript levels vary directly with

Catherine M. McEntee; Robin Cantwell; Mahboob U. Rahman; Alan P. Hudson

1993-01-01

200

Role of cyclic AMP in regulation of hepatic glucose production during exercise.  

PubMed

Cyclic AMP increases in liver during exercise, the magnitude of the increase being dependent on duration and intensity of the exercise. Within limits, the increase in cAMP is closely correlated with the rate of glycogenolysis and with the exercise intensity. It is unlikely that epinephrine is involved in determining cAMP concentration in liver during exercise. Adrenodemedullated rats show no impairment in exercise-induced liver glycogenolysis or in the increase in cAMP. When epinephrine is infused at different rates into exercising rats, liver cAMP appears to be unrelated to plasma epinephrine. The rise in plasma glucagon is likely responsible for the increase in hepatic cAMP during exercise. The increase in cAMP is apparently necessary for maintaining low levels of fructose-2,6-bisphosphate (the activator of PFK-1 and inhibitor of fructose-1,6-bisphosphate) in liver. The low fructose-2,6-bisphosphate concentration would be expected to result in an increase rate of gluconeogenesis during exercise. PMID:2853270

Winder, W W

1988-12-01

201

Cyclic AMP mediated arrhythmias induced in the ischaemic pig heart  

Microsoft Academic Search

Summary Ligation of the anterior descending coronary artery two-thirds from its origin in the pig was found to precipitate ventricular arrhythmias and fibrillation, starting approximately 20 min post-ligation, which were associated with regional accumulation of myocardial cAMP in the ischaemic area. When the arrhythmias stopped, cyclic AMP levels in the ischaemic zone were decreased. Arrhythmias could then be induced by

T. PodzuweitO; D. J. Elsl; J. McCarthy

1981-01-01

202

Automated Gamma-Flo radioimmunoassay of urinary cyclic AMP  

Microsoft Academic Search

The Gammaflow automated assay concept of Brooker et al. was adapted to the assay of urinary cyclic AMP in patients' samples on the now commercially available Squibb Gamma-Flo system, a totally automated continuous-flow immunoassay instrument. The instrument aspirates the unknown sample, combines it with radioligand and specific antiserum, incubates the mixture, separates antibody-bound radioligand from free radioligand, counts the radioactivity

G. Brooker; F. Murad

1980-01-01

203

Dictyostelium discoideum lipids modulate cell-cell cohesion and cyclic AMP signaling.  

PubMed Central

During Dictyostelium discoideum development, cell-cell communication is mediated through cyclic AMP (cAMP)-induced cAMP synthesis and secretion (cAMP signaling) and cell-cell contact. Cell-cell contact elicits cAMP secretion and modulates the magnitude of a subsequent cAMP signaling response (D. R. Fontana and P. L. Price, Differentiation 41:184-192, 1989), demonstrating that cell-cell contact and cAMP signaling are not independent events. To identify components involved in the contact-mediated modulation of cAMP signaling, amoebal membranes were added to aggregation-competent amoebae in suspension. The membranes from aggregation-competent amoebae inhibited cAMP signaling at all concentrations tested, while the membranes from vegetative amoebae exhibited a concentration-dependent enhancement or inhibition of cAMP signaling. Membrane lipids inhibited cAMP signaling at all concentrations tested. The lipids abolished cAMP signaling by blocking cAMP-induced adenylyl cyclase activation. The membrane lipids also inhibited amoeba-amoeba cohesion at concentrations comparable to those which inhibited cAMP signaling. The phospholipids and neutral lipids decreased cohesion and inhibited the cAMP signaling response. The glycolipid/sulfolipid fraction enhanced cohesion and cAMP signaling. Caffeine, a known inhibitor of cAMP-induced adenylyl cyclase activation, inhibited amoeba-amoeba cohesion. These studies demonstrate that endogenous lipids are capable of modulating amoeba-amoeba cohesion and cAMP-induced activation of the adenylyl cyclase. These results suggest that cohesion may modulate cAMP-induced adenylyl cyclase activation. Because the complete elimination of cohesion is accompanied by the complete elimination of cAMP signaling, these results further suggest that cohesion may be necessary for cAMP-induced adenylyl cyclase activation in D. discoideum.

Fontana, D R; Luo, C S; Phillips, J C

1991-01-01

204

Cyclic AMP-Mediated Cyst Expansion  

PubMed Central

In polycystic kidney disease (PKD), intracellular cAMP promotes cyst enlargement by stimulating mural epithelial cell proliferation and transepithelial fluid secretion. The proliferative effect of cAMP in PKD is unique in that cAMP is anti-mitogenic in normal renal epithelial cells. This phenotypic difference in the proliferative response to cAMP appears to involve cross-talk between cAMP and Ca2+ signaling to B-Raf, a kinase upstream of the MEK/ERK pathway. In normal cells, B-Raf is repressed by Akt (protein kinase B), a Ca2+-dependent kinase, preventing cAMP activation of ERK and cell proliferation. In PKD cells, disruption of intracellular Ca2+ homeostasis due to mutations in the PKD genes relieves Akt inhibition of B-Raf, allowing cAMP stimulation of B-Raf, ERK and cell proliferation. Fluid secretion by cystic cells is driven by cAMP-dependent transepithelial Cl? secretion involving apical cystic fibrosis transmembrane conductance regulator (CFTR) Cl? channels. This review summarizes the current knowledge of cAMP-dependent cyst expansion, focusing on cell proliferation and Cl?-dependent fluid secretion, and discusses potential therapeutic approaches to inhibit renal cAMP production and its downstream effects on cyst enlargement.

Wallace, Darren P.

2010-01-01

205

Multiple regulatory elements in the interleukin-6 gene mediate induction by prostaglandins, cyclic AMP, and lipopolysaccharide.  

PubMed Central

Induction of interleukin-6 (IL-6) gene expression is mediated by numerous agents involving all major signal transduction pathways. We have compared the effects of prostaglandins and their second messenger cyclic AMP (cAMP) with the effect of lipopolysaccharide (LPS) on IL-6 gene expression. We demonstrate that secretion of IL-6 is induced by cAMP in murine monocytic PU5-1.8 cells, even though to a lesser extent than by LPS. Nevertheless, cAMP and prostaglandins of the E series in the presence of theophylline induce transcription of the IL-6 promoter more strongly than LPS, suggesting distinctive effects of cAMP and LPS on posttranscriptional events. Mutations within four regulatory elements, namely, the multiple response element (MRE), AP-1, NF-IL6, and NF-kappa B sites, significantly reduce, but do not completely abrogate, inducibility by cAMP and prostaglandin E1, whereas alterations of four additional sites have no effects. LPS-induced promoter activity, however, is almost completely abolished by mutations in the NF-kappa B site, suggesting that a single regulatory element is crucial for inducibility by LPS. Stimulation by cAMP is correlated with the binding of inducible factors to the AP-1, NF-IL6, and NF-kappa B elements, whereas factors binding to the MRE are constitutively expressed. Recombinant cAMP response element-binding protein binds to the MRE, indicating a potential role for this factor in the cAMP response. Our results suggest that cAMP and prostaglandins act through multiple, partially redundant regulatory elements to induce IL-6 expression in monocytic cells. Nuclear events that overlap partially with the LPS response but also exhibit distinctive features are involved. Images

Dendorfer, U; Oettgen, P; Libermann, T A

1994-01-01

206

RNA-Based Fluorescent Biosensors for Live Cell Imaging of Second Messengers Cyclic di-GMP and Cyclic AMP-GMP.  

PubMed

Cyclic dinucleotides are an important class of signaling molecules that regulate a wide variety of pathogenic responses in bacteria, but tools for monitoring their regulation in vivo are lacking. We have designed RNA-based fluorescent biosensors for cyclic di-GMP and cyclic AMP-GMP by fusing the Spinach aptamer to variants of a natural GEMM-I riboswitch. In live cell imaging experiments, these biosensors demonstrate fluorescence turn-on in response to cyclic dinucleotides, and they were used to confirm in vivo production of cyclic AMP-GMP by the enzyme DncV. PMID:23488798

Kellenberger, Colleen A; Wilson, Stephen C; Sales-Lee, Jade; Hammond, Ming C

2013-03-21

207

Unlike thyrotropin, thyroid-stimulating antibodies do not activate phospholipase C in human thyroid slices.  

PubMed Central

The effects of thyroid-stimulating antibodies (TSAb) and of thyrotropin (TSH) were compared, on the generation of cyclic AMP and inositol phosphates (InsP), in human thyroid slices incubated in vitro, and on the Rapoport cyclic AMP bioassay. The TSAb positive sera were obtained from 19 patients with Graves' disease. In 14 experiments with the slices system, TSH significantly increased cyclic AMP accumulation (TSH, 0.03-10 mU/ml) as well as the cyclic AMP-independent inositol trisphosphate (InsP3) generation (TSH, 1-10 mU/ml). In the same 14 experiments, TSAb (0.10-28 mg/ml) enhanced cyclic AMP intracellular levels as expected while they did not induce any InsP accumulation. Even when TSAb increased cyclic AMP levels to the same or higher values as those obtained with TSH concentrations allowing InsP3 generation. TSAb were still unable to activate the phosphatidylinositol-Ca2+ cascade. The patterns of the response curves of TSAb and TSH on cyclic AMP accumulation were different, suggesting that different mechanisms may be involved. In addition, unlike TSH, TSAb were not able to stimulate H2O2 generation, which in human tissue mainly depends on the activation of the phosphatidylinositol-Ca2+ cascade. Immunoglobulins from six additional Graves' patients lacking measurable cyclic AMP-stimulating activity in both slices and cells systems did not activate phospholipase C either. In conclusion, our results show that TSAb do not share all the metabolic actions of TSH on human thyroid tissue. The data provide support for the concept that the pathogenesis of Graves' disease can be fully accounted for by the ability of TSAb to stimulate adenylate cyclase. This work also confirms that TSH activates the cyclic AMP and the phosphatidylinositol cascade by independent pathways in the human thyroid.

Laurent, E; Van Sande, J; Ludgate, M; Corvilain, B; Rocmans, P; Dumont, J E; Mockel, J

1991-01-01

208

Defect in cyclic AMP phosphodiesterase due to the dunce mutation of learning in Drosophila melanogaster  

Microsoft Academic Search

Cyclic AMP is an intracellular mediator (`second messenger') in the nervous and endocrine control of cellular function, regulating different processes in different cell types. Although evidence is incomplete, it seems that cyclic AMP enhances the calcium-mediated release of neurotransmitter in some neurones1-3. A simple form of memory in the mollusc Aplysia is probably encoded as a cyclic AMP-induced enhancement of

Duncan Byers; Ronald L. Davis; John A. Kiger

1981-01-01

209

Reduction of cyclic AMP levels by light and by cone degeneration  

Microsoft Academic Search

Dark-adapted retinas or whole eyes of 13-line ground squirrels (Citellus tridecemlineatus) and western fence lizards (Sceloporus occidentalis) contain higher levels of cyclic AMP than of cyclic GMP. In these cone-dominant retinas, light reduces cyclic AMP content selectively. Freezing of dark- or light-adapted retinas or eyes also reduces cyclic AMP content, with only minimal changes in cyclic GMP levels. In addition,

Debora B. Farber; Dennis W. Souza; David G. Chase; Richard N. Lolley

210

cap alpha. â-Adrenergic receptor-mediated sensitization of forskolin-stimulated cyclic AMP production  

Microsoft Academic Search

Preincubation of HT29 human colonic adenocarcinoma cells with ..cap alpha..â-adrenergic agonists resulted in a 10- to 20-fold increase in forskolin-stimulated cyclic AMP production as compared to cells preincubated without agonist. Similar results were obtained using either a (³H)adenine prelabeling assay or a cyclic AMP radioimmunoassay to measure cyclic AMP levels. This phenomenon, which is termed sensitization, is ..cap alpha..â-adrenergic receptor-mediated

S. B. Jones; M. L. Toews; J. T. Turner; D. B. Bylund

1987-01-01

211

Regulation of cyclic GMP, cyclic AMP and lactate dehydrogenase by putative neurotransmitters in the C6 rat glioma cell line  

Microsoft Academic Search

In C6 cells norepinephrine and dopamine caused transient increases in cyclic GMP and cyclic AMP, as well as an induction of lactate dehydrogenase. All of these responses were blocked by l-propranolol, suggesting mediation by a ..beta..-receptor. Phentolamine potentiated the NE-increased cAMP levels by 5-fold when NE was used at suboptimal doses, suggesting the presence of ..cap alpha..-adrenergic receptors in C6

Jane E. Bottenstein; Jean de Vellis

1978-01-01

212

Regulation of cyclic GMP, cyclic amp and lactate dehydrogenase by putative neutrotransmitters in the C6 rat glioma cell line  

Microsoft Academic Search

In C6 cells norepinephrine and dopamine caused transient increases in cyclic GMP and cyclic AMP, as well as an induction of lactate dehydrogenase. All of these responses were blocked by 1-propranolol, suggesting mediation by a ..beta..-receptor. Phentolamine potentiated the NE-increased cAMP levels by 5-fold when NE was used at suboptimal doses, suggesting the presence of ..cap alpha..-adrenergic receptors in C6

J. E. Bottenstein; J. de Vellis

1977-01-01

213

Adriamycin inhibits PTH-mediated but not PGE 2 -mediated stimulation of cyclic AMP formation in isolated bone cells  

Microsoft Academic Search

Summary  We have examined the effect of adriamycin, an anthracycline antibiotic which modifies plasma membrane functions, on the cyclic\\u000a AMP response to PTH and PGE2 in isolated osteoblastlike cells. Adriamycin blunted the increment in bone cell cyclic AMP caused by exposure to PTH. This\\u000a effect appeared rapidly (within 3 min after bone cells were exposed to adriamycin) and disappeared soon after

Gail Kohler; Victor Shen; William A. Peck

1984-01-01

214

Cyclic AMP can promote APL progression and protect myeloid leukemia cells against anthracycline-induced apoptosis  

PubMed Central

We show that cyclic AMP (cAMP) elevating agents protect blasts from patients with acute promyelocytic leukemia (APL) against death induced by first-line anti-leukemic anthracyclines like daunorubicin (DNR). The cAMP effect was reproduced in NB4 APL cells, and shown to depend on activation of the generally cytoplasmic cAMP-kinase type I (PKA-I) rather than the perinuclear PKA-II. The protection of both NB4 cells and APL blasts was associated with (inactivating) phosphorylation of PKA site Ser118 of pro-apoptotic Bad and (activating) phosphorylation of PKA site Ser133 of the AML oncogene CREB. Either event would be expected to protect broadly against cell death, and we found cAMP elevation to protect also against 2-deoxyglucose, rotenone, proteasome inhibitor and a BH3-only mimetic. The in vitro findings were mirrored by the findings in NSG mice with orthotopic NB4 cell leukemia. The mice showed more rapid disease progression when given cAMP-increasing agents (prostaglandin E2 analog and theophylline), both with and without DNR chemotherapy. The all-trans retinoic acid (ATRA)-induced terminal APL cell differentiation is a cornerstone in current APL treatment and is enhanced by cAMP. We show also that ATRA-resistant APL cells, believed to be responsible for treatment failure with current ATRA-based treatment protocols, were protected by cAMP against death. This suggests that the beneficial pro-differentiating and non-beneficial pro-survival APL cell effects of cAMP should be weighed against each other. The results suggest also general awareness toward drugs that can affect bone marrow cAMP levels in leukemia patients.

Gausdal, G; Wergeland, A; Skavland, J; Nguyen, E; Pendino, F; Rouhee, N; McCormack, E; Herfindal, L; Kleppe, R; Havemann, U; Schwede, F; Bruserud, ?; Gjertsen, B T; Lanotte, M; Segal-Bendirdjian, E; D?skeland, S O

2013-01-01

215

Cyclic AMP can promote APL progression and protect myeloid leukemia cells against anthracycline-induced apoptosis.  

PubMed

We show that cyclic AMP (cAMP) elevating agents protect blasts from patients with acute promyelocytic leukemia (APL) against death induced by first-line anti-leukemic anthracyclines like daunorubicin (DNR). The cAMP effect was reproduced in NB4 APL cells, and shown to depend on activation of the generally cytoplasmic cAMP-kinase type I (PKA-I) rather than the perinuclear PKA-II. The protection of both NB4 cells and APL blasts was associated with (inactivating) phosphorylation of PKA site Ser118 of pro-apoptotic Bad and (activating) phosphorylation of PKA site Ser133 of the AML oncogene CREB. Either event would be expected to protect broadly against cell death, and we found cAMP elevation to protect also against 2-deoxyglucose, rotenone, proteasome inhibitor and a BH3-only mimetic. The in vitro findings were mirrored by the findings in NSG mice with orthotopic NB4 cell leukemia. The mice showed more rapid disease progression when given cAMP-increasing agents (prostaglandin E2 analog and theophylline), both with and without DNR chemotherapy. The all-trans retinoic acid (ATRA)-induced terminal APL cell differentiation is a cornerstone in current APL treatment and is enhanced by cAMP. We show also that ATRA-resistant APL cells, believed to be responsible for treatment failure with current ATRA-based treatment protocols, were protected by cAMP against death. This suggests that the beneficial pro-differentiating and non-beneficial pro-survival APL cell effects of cAMP should be weighed against each other. The results suggest also general awareness toward drugs that can affect bone marrow cAMP levels in leukemia patients. PMID:23449452

Gausdal, G; Wergeland, A; Skavland, J; Nguyen, E; Pendino, F; Rouhee, N; McCormack, E; Herfindal, L; Kleppe, R; Havemann, U; Schwede, F; Bruserud, O; Gjertsen, B T; Lanotte, M; Ségal-Bendirdjian, E; Døskeland, S O

2013-02-28

216

Stoichiometry and structural effect of the cyclic nucleotide binding to cyclic AMP receptor protein.  

PubMed

Cyclic AMP receptor protein (CRP) is a homodimeric protein, which is activated by cAMP binding to function as a transcriptional regulator of many genes in prokaryotes. Until now, the actual number of cAMP molecules that can be bound by CRP in solution has been ambiguous. In this work, we performed a nuclear magnetic resonance study on CRP to investigate the stoichiometry of cyclic nucleotide binding to CRP. A series of (1)H-(15)N heteronuclear single quantum coherence (HSQC) spectra of the protein in the absence and in the presence of cAMP or cGMP were analyzed. The addition of cAMP to CRP induced a biphasic spectral change up to 4 equivalents, whereas the cGMP addition made a monophasic change up to 2 equivalents. Altogether, the results not only established for the first time that CRP possesses two cyclic AMP-binding sites in each monomer, even in a solution without DNA, but also suggest that the syn-cAMP binding sites of the CRP dimer can be formed by an allosteric conformational change of the protein upon the binding of two anti-cAMPs at the N-terminal domain. In addition, a residue-specific inspection of the spectral changes provides some new structural information about the cAMP-induced allosteric activation of CRP. PMID:11781328

Won, Hyung-Sik; Lee, Tae-Woo; Park, Sang-Ho; Lee, Bong-Jin

2002-01-07

217

Calcium- and cyclic AMP-dependent chloride secretion in human colonic epithelia.  

PubMed Central

Three stable epithelial cell lines (HCA-7, HCA-7-Col 1 and HCA-7-Col 3) all derived from the same human adenocarcinoma have been cultured on collagen-coated Millipore filters. These epithelial monolayers have been used to record short circuit current (SCC) in response to of secretagogues. Similar monolayers, but grown on plastic dishes, were used for measurements of tissue cyclic AMP. Lysylbradykinin, applied to either side of the monolayers, increased SCC in HCA-7 cells but had little effect on the other two lines. The responses showed rapid desensitization, which could be prevented by cooling to 4 degrees C. Responses to kinin were not significantly attenuated by piroxicam, an inhibitor of cyclo-oxygenase. Other secretagogues, vasoactive intestinal polypeptide (VIP) and carbachol also increased SCC in monolayers. The responses to VIP were greatest in HCA-7-Col 1 monolayers while responses were virtually absent in HCA-7-Col 3. A similar profile was seen with carbachol except that responses of HCA-7 and HCA-7-Col 1 monolayers were more equal. With one exception the responses to VIP and carbachol showed sidedness, acting only from the basolateral side. The effects of the secretagogues were inhibited by piretanide, a loop diuretic, applied basolaterally. It is presumed that SCC responses represent electrogenic chloride secretion. Treatment with forskolin increased SCC in HCA-7 and HCA-7-Col 1 monolayers with little effect in HCA-7-Col 3. Nevertheless cyclic AMP levels were elevated most in HCA-7-Col 3 and least in HCA-7-Col 1 monolayers, in reciprocal relationship to the functional response. A23187 increased SCC when applied to HCA-7 and HCA-7-Col 3 monolayers with little effect on HCA-7-Col 1. The differential responses of the three human cell lines provide unique opportunities to discover the functional responsibilities of entities involved in the chloride secretory process. HCA-7-Col 3 cells which generate high levels of cyclic AMP in response to forskolin but which fail to show a substantial chloride secretory response may be a useful model of some disease conditions. Images Figure 10

Cuthbert, A. W.; Egleme, C.; Greenwood, H.; Hickman, M. E.; Kirkland, S. C.; MacVinish, L. J.

1987-01-01

218

Effects of a bone resorptive factor from human cancer ascites fluid on rat bone cell calcium and cyclic AMP  

Microsoft Academic Search

Summary  The effects of a bone resorptive protein isolated from human cancer ascites fluid on bone cell calcium and cyclic AMP were\\u000a studied with fetal rat cells. The osteoclast-activating factor increased bone cell calcium uptake at 37°C and 4°C with no\\u000a direct effects on calcium efflux. Concentrations of the resorptive factor that increased in vitro bone resorption and cell\\u000a calcium uptake

R. Dziak; Y. W. Chang; D. Humphries; W. Lloyd; H. Wells; K. Schmid; R. B. Nimberg

1980-01-01

219

Tissue-specific enhancer of the human glycoprotein hormone alpha-subunit gene: dependence on cyclic AMP-inducible elements.  

PubMed Central

We identified and characterized elements which confer tissue specificity and cyclic AMP (cAMP) responsiveness to the human glycoprotein alpha-subunit gene. An enhancer containing an 18-base-pair repeat conferred cAMP responsiveness in a non-tissue-specific fashion. DNase I protection assays revealed DNA-binding factors that bound to this element in both placental and nonplacental cells. It also enhanced the alpha-subunit promoter in a tissue-specific manner but had a negligible effect on a heterologous promoter. A unique element found upstream of this enhancer had no independent activity but, in combination with the cAMP-responsive enhancer, distinctly increased the tissue-specific activity of both the alpha-subunit promoter and a heterologous promoter. A factor that bound to this upstream element was found in placental but not nonplacental cells. We conclude that this novel element acts, perhaps through a specific trans-acting factor, in concert with a cAMP-responsive enhancer to confer tissue specificity to the alpha-subunit gene. Images

Delegeane, A M; Ferland, L H; Mellon, P L

1987-01-01

220

Effects of cyclic AMP- and cyclic GMP- phosphodiesterase inhibitors on immunological release of histamine and on lung contraction.  

PubMed

1 Cyclic adenosine 3',5'-monophosphate (cyclic AMP)- and cyclic guanosine 3',5'-monophosphate (cyclic GMP)-phosphodiesterase activities from rat lung were selectively inhibited by ZK 62711 and M & B 22948, respectively. Theophylline and papaverine inhibited both activities. 2 Rat lung strips contracted by carbachol were relaxed by 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (ZK 26711, EC25 = 7 x 10(-8)M) and 2-O-propoxyphenyl-8-azapurin-6-one (M & B 22948, EC25 = 5 x 10(-7)M) indicating relaxant properties of both cyclic AMP and cyclic GMP. 3 The antigen-induced histamine release from human basophils was inhibited by ZK 62711 (IC25 = 8 x 10(-7)M), whereas M & B 22948 had no effect. On the contrary, the release from rat mast cells was inhibited by M & B 22948 (IC25 = 10(-6)M), while ZK 62711 had no effect. 4 These data show an inhibitory effect of cyclic AMP on histamine release to be involved with basophils, whereas cyclic GMP is predominantly involved with mast cells. Is is suggested that the antianaphylactic properties of cyclic nucleotide phosphodiesterase inhibitors are mainly linked to the increase of cyclic GMP. PMID:6168323

Frossard, N; Landry, Y; Pauli, G; Ruckstuhl, M

1981-08-01

221

Effects of cyclic AMP- and cyclic GMP- phosphodiesterase inhibitors on immunological release of histamine and on lung contraction.  

PubMed Central

1 Cyclic adenosine 3',5'-monophosphate (cyclic AMP)- and cyclic guanosine 3',5'-monophosphate (cyclic GMP)-phosphodiesterase activities from rat lung were selectively inhibited by ZK 62711 and M & B 22948, respectively. Theophylline and papaverine inhibited both activities. 2 Rat lung strips contracted by carbachol were relaxed by 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (ZK 26711, EC25 = 7 x 10(-8)M) and 2-O-propoxyphenyl-8-azapurin-6-one (M & B 22948, EC25 = 5 x 10(-7)M) indicating relaxant properties of both cyclic AMP and cyclic GMP. 3 The antigen-induced histamine release from human basophils was inhibited by ZK 62711 (IC25 = 8 x 10(-7)M), whereas M & B 22948 had no effect. On the contrary, the release from rat mast cells was inhibited by M & B 22948 (IC25 = 10(-6)M), while ZK 62711 had no effect. 4 These data show an inhibitory effect of cyclic AMP on histamine release to be involved with basophils, whereas cyclic GMP is predominantly involved with mast cells. Is is suggested that the antianaphylactic properties of cyclic nucleotide phosphodiesterase inhibitors are mainly linked to the increase of cyclic GMP.

Frossard, N.; Landry, Y.; Pauli, G.; Ruckstuhl, M.

1981-01-01

222

Differential Redistribution of Protein Kinase C Isoforms by Cyclic AMP in HL60 Cells  

Microsoft Academic Search

In this study we have analyzed the distribution of protein kinase C isoforms in cytosol, membrane, and nucleus in HL60 cells. Furthermore, we have studied the redistribution of these isoforms after cyclic AMP treatment. Protein kinase C localization and cyclic AMP-induced translocation was demonstrated by Western blot analysis. Cytosol, membrane and nucleus in HL60 cells expressed the abundance of protein

Begoña G. Miguel; M. Carmen Calcerrada; Felic??sima Mata; Patricio Aller; Roberto Clemente; R. Edgardo Catalán; Ana M. Mart??nez

2000-01-01

223

The Small Molecule Triclabendazole Decreases the Intracellular Level of Cyclic AMP and Increases Resistance to Stress in Saccharomyces cerevisiae  

PubMed Central

The Ras-adenylyl cyclase-protein kinase A nutrient-sensing pathway controls metabolism, proliferation and resistance to stress in Saccharomyces cerevisiae. The genetic disruption of this pathway increases resistance to a variety of stresses. We show here that the pharmacological inhibition of this pathway by the drug triclabendazole increases resistance to oxidants, heat stress and extends the chronological life. Evidence is presented that triclabendazole decreases the intracellular level of cyclic AMP by inhibiting adenylyl cyclase and triggers the parallel rapid translocation of the stress-resistance transcription factor Msn2 from the cytosol into the nucleus, as deduced from experiments employing a strain in which MSN2 is replaced with MSN2-GFP (GFP, green fluorescent protein). Msn2 and Msn4 are responsible for activating the transcription of numerous genes that encode proteins that protect cells from stress. The results are consistent with triclabendazole either inhibiting the association of Ras with adenylyl cyclase or directly inhibiting adenylyl cyclase, which in turn triggers Msn2/4 to enter the nucleus and activate stress-responsible element gene expression.

Lee, Yong Joo; Shi, Runhua; Witt, Stephan N.

2013-01-01

224

Effects of Chronic Lithium Treatment on Protein Kinase C and Cyclic AMP-Dependent Protein Phosphorylation. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

Lithium inhibits the agonist-induced hydrolysis of phosphoinositides and the synthesis of cyclic AMP (cAMP) in rat brain preparations, each of which is linked to activation of specific protein kinases. Therefore, we examine the effects of chronic lithium ...

T. L. Casebolt R. S. Jope

1991-01-01

225

Effect of cyclic AMP and some structural analogues on the dark repair inhibition by caffeine of UV-irradiated cells  

Microsoft Academic Search

Summary The effect of cyclic AMP and some structural analogues on the dark-repair inhibition by caffeine has been studied. Cyclic AMP had no significant effect, contrary to the previous report by Wackeret al. [5], on the dark-repair inhibition by caffeine. Some cyclic AMP derivatives, resistent to hydrolysis by the phosphodiesterase enzyme, were used to investigate the role of phosphodiesterase in

P. Chandra; R. E. O. Scheckel; A. Wacker

1974-01-01

226

The Pseudomonas aeruginosa Vfr regulator controls global virulence factor expression through cyclic AMP-dependent and -independent mechanisms.  

PubMed

Vfr is a global regulator of virulence factor expression in the human pathogen Pseudomonas aeruginosa. Although indirect evidence suggests that Vfr activity is controlled by cyclic AMP (cAMP), it has been hypothesized that the putative cAMP binding pocket of Vfr may accommodate additional cyclic nucleotides. In this study, we used two different approaches to generate apo-Vfr and examined its ability to bind a representative set of virulence gene promoters in the absence and presence of different allosteric effectors. Of the cyclic nucleotides tested, only cAMP was able to restore DNA binding activity to apo-Vfr. In contrast, cGMP was capable of inhibiting cAMP-Vfr DNA binding. Further, we demonstrate that vfr expression is autoregulated and cAMP dependent and involves Vfr binding to a previously unidentified site within the vfr promoter region. Using a combination of in vitro and in vivo approaches, we show that cAMP is required for Vfr-dependent regulation of a specific subset of virulence genes. In contrast, we discovered that Vfr controls expression of the lasR promoter in a cAMP-independent manner. In summary, our data support a model in which Vfr controls virulence gene expression by distinct (cAMP-dependent and -independent) mechanisms, which may allow P. aeruginosa to fine-tune its virulence program in response to specific host cues or environments. PMID:20494996

Fuchs, Erin L; Brutinel, Evan D; Jones, Adriana K; Fulcher, Nanette B; Urbanowski, Mark L; Yahr, Timothy L; Wolfgang, Matthew C

2010-05-21

227

Mitigation of Chlorine Lung Injury by Increasing Cyclic AMP Levels  

PubMed Central

Chlorine is considered a chemical threat agent to which humans may be exposed as a result of accidental or intentional release. Chlorine is highly reactive, and inhalation of the gas causes cellular damage to the respiratory tract, inflammation, pulmonary edema, and airway hyperreactivity. Drugs that increase intracellular levels of the signaling molecule cyclic AMP (cAMP) may be useful for treatment of acute lung injury through effects on alveolar fluid clearance, inflammation, and airway reactivity. This article describes mechanisms by which cAMP regulates cellular processes affecting lung injury and discusses the basis for investigating drugs that increase cAMP levels as potential treatments for chlorine-induced lung injury. The effects of ?2-adrenergic agonists, which stimulate cAMP synthesis, and phosphodiesterase inhibitors, which inhibit cAMP degradation, on acute lung injury are reviewed, and the relative advantages of these approaches are compared.

Hoyle, Gary W.

2010-01-01

228

Activation by Adenosine 3?:5?-Monophosphate of a Membrane-Bound Phosphoprotein Phosphatase from Toad Bladder  

PubMed Central

Adenosine 3?:5?-monophosphate (cyclic AMP) caused a decrease in the net rate of incorporation of radioactive phosphate into a specific protein (protein D) in a membrane fraction from toad bladder. Moreover, when the membrane protein was prelabeled with radioactive phosphate, cyclic AMP caused an increase in the net rate of removal of radioactive phosphate from this specific protein. Certain agents were shown to be selective inhibitors of membrane-bound protein D kinase or protein D phosphatase. With the help of these agents, it was concluded that cyclic AMP caused the activation of membrane-bound protein D phosphatase. The present data, together with earlier studies, are compatible with the possibility that the cyclic AMP-induced activation of a membrane-bound phosphoprotein phosphatase in toad bladder, with the consequent dephosphorylation of protein D, may be responsible for the physiological effects of antidiuretic hormone on sodium and/or water transport in this tissue.

Delorenzo, Robert J.; Greengard, Paul

1973-01-01

229

SRA5 encodes the low-Km cyclic AMP phosphodiesterase of Saccharomyces cerevisiae.  

PubMed Central

sra5 mutations in Saccharomyces cerevisiae were previously shown to suppress the inefficient growth of ras2 strains on nonfermentable carbon sources and to result in deficient low-Km cyclic AMP (cAMP) phosphodiesterase activity. We have cloned SRA5 by complementation. It maps to the right arm of chromosome XV, tightly linked to PRT1, and its sequence matches the sequence of PDE2, encoding the low-Km cAMP phosphodiesterase. Disruptions of SRA5 allowed ras1 ras2 strains to grow either on rich media supplemented with cAMP or on minimal media without exogenous cAMP. sra5 strains failed to survive prolonged nitrogen starvation in the presence of exogenous cAMP. Images

Wilson, R B; Tatchell, K

1988-01-01

230

Changes of concentration of cyclic AMP in rat brain and plasma in the clinical death model.  

PubMed

In the experimental model of clinical death in rats (Korpachev et al. 1982) cyclic AMP concentrations were evaluated in the brain and plasma at the end of 5-min clinical death, and 5, 15, 30, 60 and 120 min after resuscitation. The cAMP 125I assay system has been used. At the end of clinical death the cAMP level decreased in the brain with normalization 15 min after resuscitation; the second decrease of the cAMP level was observed 30 min post resuscitation with normalization in later periods. In the plasma cAMP concentration did not change at the end of clinical death, followed by a significant increase 5 min after resuscitation. Later the level of plasma cAMP decreased being still above the control value after 2 hours. The possible role of endogenous catecholamines stimulation on adenylate cyclase activity is discussed. PMID:1667542

Kapu?ci?ski, A

1991-01-01

231

Cyclic AMP-inducible genes respond uniformly to seasonal lighting conditions in the rat pineal gland.  

PubMed

The encoding of photoperiodic information ensues in terms of the daily profile in the expression of cyclic AMP (cAMP)-inducible genes such as the arylalkylamine N-acetyltransferase (AA-NAT) gene that encodes the rate-limiting enzyme in melatonin formation. In the present study, we compared the influence of the photoperiodic history on the cAMP-inducible genes AA-NAT, inducible cyclic AMP early repressor (ICER), fos-related antigen-2 (FRA-2), mitogen-activated protein kinase phosphatase-1 (MKP-1), nerve growth factor inducible gene-A (NGFI-A) and nerve growth factor inducible gene-B (NGFI-B) in the pineal gland of rats. For this purpose, we monitored the daily profiles of each gene in the same pineal gland under a long (light/dark 16:8) and a short (light/dark 8:16) photoperiod by measuring the respective mRNA amounts by real-time polymerase chain reaction analysis. We found that, for all genes under investigation, the duration of increased nocturnal expression is lengthened and, in relation to light onset, the nocturnal rise is earlier under the long photoperiod (light/dark 16:8). Furthermore, with the exception of ICER, all other cAMP-inducible genes tend to display higher maximum expression under light/dark 8:16 than under light/dark 16:8. Photoperiod-dependent changes persist for all of the cAMP-inducible genes when the rats are kept for two cycles under constant darkness. Therefore, all cAMP-inducible genes are also influenced by the photoperiod of prior entrained cycles. Our study indicates that, despite differences regarding the expressional control and the temporal phasing of the daily profile, cAMP-inducible genes are uniformly influenced by photoperiodic history in the rat pineal gland. PMID:16962714

Spessert, R; Gupta, B B P; Rohleder, N; Gerhold, S; Engel, L

2006-09-08

232

Cyclic AMP Control Measured in Two Compartments in HEK293 Cells: Phosphodiesterase KM Is More Important than Phosphodiesterase Localization  

PubMed Central

The intracellular second messenger cyclic AMP (cAMP) is degraded by phosphodiesterases (PDE). The knowledge of individual families and subtypes of PDEs is considerable, but how the different PDEs collaborate in the cell to control a cAMP signal is still not fully understood. In order to investigate compartmentalized cAMP signaling, we have generated a membrane-targeted variant of the cAMP Bioluminiscence Resonance Energy Transfer (BRET) sensor CAMYEL and have compared intracellular cAMP measurements with it to measurements with the cytosolic BRET sensor CAMYEL in HEK293 cells. With these sensors we observed a slightly higher cAMP response to adenylyl cyclase activation at the plasma membrane compared to the cytosol, which is in accordance with earlier results from Fluorescence Resonance Energy Transfer (FRET) sensors. We have analyzed PDE activity in fractionated lysates from HEK293 cells using selective PDE inhibitors and have identified PDE3 and PDE10A as the major membrane-bound PDEs and PDE4 as the major cytosolic PDE. Inhibition of membrane-bound or cytosolic PDEs can potentiate the cAMP response to adenylyl cyclase activation, but we see no significant difference between the potentiation of the cAMP response at the plasma membrane and in cytosol when membrane-bound and cytosolic PDEs are inhibited. When different levels of stimulation were tested, we found that PDEs 3 and 10 are mainly responsible for cAMP degradation at low intracellular cAMP concentrations, whereas PDE4 is more important for control of cAMP at higher concentrations.

Matthiesen, Karina; Nielsen, Jacob

2011-01-01

233

Stimulation of cyclic AMP production in chick renal tissue by cadmium and manganese.  

PubMed

The effects of cadmium on production of cyclic AMP by partially purified chick renal plasma membrane preparations and binding of 125I-parathyrin to the membranes have been investigated. At certain concentrations Cd2+ ions (and Mn2+ ions) markedly stimulated the production of cyclic AMP by the tissue. It was found that concentrations of Cd2+ roughly in the same range were also capable of stimulating binding of 125I-parathyrin to the membrane preparations. PMID:2995580

Cook, D B; Dewar, J H; Ershadi, S S

1985-07-01

234

Gating by Cyclic AMP: Expanded Role for an Old Signaling Pathway  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. The intracellular signal transduction pathway that utilizes cyclic AMP as a key messenger was the first such pathway to be described and has served as a model for many other transducing systems. Now Iyengar illustrates how this classic pathway has yet another function--in a number of different biological systems, the cyclic AMP pathway appears to gate (either negatively or positively) other signal transduction pathways.

Ravi Iyengar (City University of New York;Department of Pharmacology, Mount Sinai School of Medicine)

1996-01-26

235

Adenylate Cyclase and the Cyclic AMP Receptor Protein Modulate Stress Resistance and Virulence Capacity of Uropathogenic Escherichia coli  

PubMed Central

In many bacteria, the second messenger cyclic AMP (cAMP) interacts with the transcription factor cAMP receptor protein (CRP), forming active cAMP-CRP complexes that can control a multitude of cellular activities, including expanded carbon source utilization, stress response pathways, and virulence. Here, we assessed the role of cAMP-CRP as a regulator of stress resistance and virulence in uropathogenic Escherichia coli (UPEC), the principal cause of urinary tract infections worldwide. Deletion of genes encoding either CRP or CyaA, the enzyme responsible for cAMP synthesis, attenuates the ability of UPEC to colonize the bladder in a mouse infection model, dependent on intact innate host defenses. UPEC mutants lacking cAMP-CRP grow normally in the presence of glucose but are unable to utilize alternate carbon sources like amino acids, the primary nutrients available to UPEC within the urinary tract. Relative to the wild-type UPEC isolate, the cyaA and crp deletion mutants are sensitive to nitrosative stress and the superoxide generator methyl viologen but remarkably resistant to hydrogen peroxide (H2O2) and acid stress. In the mutant strains, H2O2 resistance correlates with elevated catalase activity attributable in part to enhanced translation of the alternate sigma factor RpoS. Acid resistance was promoted by both RpoS-independent and RpoS-dependent mechanisms, including expression of the RpoS-regulated DNA-binding ferritin-like protein Dps. We conclude that balanced input from many cAMP-CRP-responsive elements, including RpoS, is critical to the ability of UPEC to handle the nutrient limitations and severe environmental stresses present within the mammalian urinary tract.

Donovan, Grant T.; Norton, J. Paul; Bower, Jean M.

2013-01-01

236

Adenylate cyclase and the cyclic AMP receptor protein modulate stress resistance and virulence capacity of uropathogenic Escherichia coli.  

PubMed

In many bacteria, the second messenger cyclic AMP (cAMP) interacts with the transcription factor cAMP receptor protein (CRP), forming active cAMP-CRP complexes that can control a multitude of cellular activities, including expanded carbon source utilization, stress response pathways, and virulence. Here, we assessed the role of cAMP-CRP as a regulator of stress resistance and virulence in uropathogenic Escherichia coli (UPEC), the principal cause of urinary tract infections worldwide. Deletion of genes encoding either CRP or CyaA, the enzyme responsible for cAMP synthesis, attenuates the ability of UPEC to colonize the bladder in a mouse infection model, dependent on intact innate host defenses. UPEC mutants lacking cAMP-CRP grow normally in the presence of glucose but are unable to utilize alternate carbon sources like amino acids, the primary nutrients available to UPEC within the urinary tract. Relative to the wild-type UPEC isolate, the cyaA and crp deletion mutants are sensitive to nitrosative stress and the superoxide generator methyl viologen but remarkably resistant to hydrogen peroxide (H(2)O(2)) and acid stress. In the mutant strains, H(2)O(2) resistance correlates with elevated catalase activity attributable in part to enhanced translation of the alternate sigma factor RpoS. Acid resistance was promoted by both RpoS-independent and RpoS-dependent mechanisms, including expression of the RpoS-regulated DNA-binding ferritin-like protein Dps. We conclude that balanced input from many cAMP-CRP-responsive elements, including RpoS, is critical to the ability of UPEC to handle the nutrient limitations and severe environmental stresses present within the mammalian urinary tract. PMID:23115037

Donovan, Grant T; Norton, J Paul; Bower, Jean M; Mulvey, Matthew A

2012-10-31

237

Cyclic AMP negatively regulates prodigiosin production by Serratia marcescens.  

PubMed

Many Serratia marcescens strains produce the red pigment prodigiosin, which has antimicrobial and anti-tumor properties. Previous reports suggest that cyclic AMP (cAMP) is a positive regulator of prodigiosin production. Supporting this model, the addition of glucose to growth medium inhibited pigment production in rich and minimal media. Unexpectedly, we observed highly elevated levels of prodigiosin production in isogenic strains with mutations in genes involved in cAMP production (cyaA and crr) and in cAMP-dependent transcriptional signaling (crp). Multicopy expression of the Escherichia coli cAMP-phosphodiesterase gene, cpdA, also conferred a striking increase in prodigiosin production. Exogenous cAMP decreased both pigment production and pigA-lacZ transcription in the wild-type (WT) strain, and pigA-lacZ transcription was significantly increased in a crp mutant relative to WT. Suppressor and epistasis analysis indicate that the hyperpigment phenotype was dependent upon pigment biosynthetic genes (pigA, pigB, pigC, pigD and pigM). These experiments establish cAMP as a negative regulator of prodigiosin production in S. marcescens. PMID:20045458

Kalivoda, Eric J; Stella, Nicholas A; Aston, Marissa A; Fender, James E; Thompson, Paul P; Kowalski, Regis P; Shanks, Robert M Q

2010-01-04

238

Cyclic AMP negatively regulates prodigiosin production by Serratia marcescens  

PubMed Central

Many Serratia marcescens strains produce the red pigment prodigiosin, which has antimicrobial and anti-tumor properties. Previous reports suggest that cyclic AMP (cAMP) is a positive regulator of prodigiosin production. Supporting this model, the addition of glucose to growth medium inhibited pigment production in rich and minimal media. Unexpectedly, we observed highly elevated levels of prodigiosin production in isogenic strains with mutations in genes involved in cAMP production (cyaA and crr) and in cAMP-dependent transcriptional signaling (crp). Multicopy expression of the Escherichia coli camp phosphodiesterase gene, cpdA, also conferred a striking increase in prodigiosin production. Exogenous cAMP decreased both pigment production and pigA-lacZ transcription in the wild-type (WT) strain, and pigA-lacZ transcription was significantly increased in a crp mutant relative to WT. Suppressor and epistasis analysis indicate that the hyperpigment phenotype was dependent upon pigment biosynthetic genes (pigA, pigB, pigC, pigD and pigM). These experiments establish cAMP as a negative regulator of prodigiosin production in S. marcescens.

Kalivoda, Eric J.; Stella, Nicholas A.; Aston, Marissa A.; Fender, James E.; Thompson, Paul P.; Kowalski, Regis P.; Shanks, Robert M. Q.

2010-01-01

239

Effects of phorbol esters and pertussis toxin on calcitonin-stimulated accumulation of cyclic AMP in neonatal mouse calvarial bones  

Microsoft Academic Search

Summary  Calcitonin (CT) is a well-known inhibitor of osteoclastic bone resorption bothin vivo andin vitro. The effect is mediated by activation of adenylate cyclase and subsequent increased levels of cyclic AMP (cAMP). We report\\u000a here that CT-induced (30 nmol\\/liter) accumulation of cAMP in cultured neonatal mouse calvaria is enhanced two-fold by 12-O-tetradecanoylphorbol-13-acetate\\u000a (TPA; 100 nmol\\/liter) and phorbol 12,13-dibutyrate (PDBU; 100 nmol\\/liter),

Maria Ransjö; Ulf H. Lerner

1991-01-01

240

Regulation of adenylate cyclase and cyclic AMP phosphodiesterase by 5-hydroxytryptamine and calcium ions in blowfly salivary-gland homogenates.  

PubMed

Salivary-gland homogenates contain 5-hydroxytryptamine-stimulated adenylate cyclase. Half-maximal stimulation was obtained with 0.1 microM-5-hydroxytryptamine in the presence of added guanine nucleotides. Gramine antagonized the stimulation of cyclase caused by 5-hydroxytryptamine. In the presence of hormone, guanosine 5'-[gamma-thio]triphosphate produced a marked activation of adenylate cyclase activity. Stimulation of adenylate cyclase by forskolin or fluoride did not require the addition of guanine nucleotides or hormone. In the presence of EGTA, Ca2+ produced a biphasic activation of cyclase activity. Ca2+ at 1-100 microM increased activity, whereas 2000 microM-Ca2+ inhibited cyclase activity. The neuroleptic drugs trifluoperazine and chlorpromazine non-specifically inhibited adenylate cyclase activity even in the absence of Ca2+. The cyclic AMP phosphodiesterase activity in homogenates was not affected by Ca2+ or exogenous calmodulin. This enzyme was also inhibited by trifluoperazine in the absence of Ca2+. These results indicate that Ca2+ elevates adenylate cyclase activity, but had no effect on cyclic AMP phosphodiesterase of salivary-gland homogenates. PMID:6288011

Litosch, I; Fradin, M; Kasaian, M; Lee, H S; Fain, J N

1982-04-15

241

Regulation of adenylate cyclase and cyclic AMP phosphodiesterase by 5-hydroxytryptamine and calcium ions in blowfly salivary-gland homogenates.  

PubMed Central

Salivary-gland homogenates contain 5-hydroxytryptamine-stimulated adenylate cyclase. Half-maximal stimulation was obtained with 0.1 microM-5-hydroxytryptamine in the presence of added guanine nucleotides. Gramine antagonized the stimulation of cyclase caused by 5-hydroxytryptamine. In the presence of hormone, guanosine 5'-[gamma-thio]triphosphate produced a marked activation of adenylate cyclase activity. Stimulation of adenylate cyclase by forskolin or fluoride did not require the addition of guanine nucleotides or hormone. In the presence of EGTA, Ca2+ produced a biphasic activation of cyclase activity. Ca2+ at 1-100 microM increased activity, whereas 2000 microM-Ca2+ inhibited cyclase activity. The neuroleptic drugs trifluoperazine and chlorpromazine non-specifically inhibited adenylate cyclase activity even in the absence of Ca2+. The cyclic AMP phosphodiesterase activity in homogenates was not affected by Ca2+ or exogenous calmodulin. This enzyme was also inhibited by trifluoperazine in the absence of Ca2+. These results indicate that Ca2+ elevates adenylate cyclase activity, but had no effect on cyclic AMP phosphodiesterase of salivary-gland homogenates.

Litosch, I; Fradin, M; Kasaian, M; Lee, H S; Fain, J N

1982-01-01

242

The effect of thyroidectomy in the fetal sheep on lung liquid reabsorption induced by adrenaline or cyclic AMP.  

PubMed Central

1. In fetal sheep at 113-120 days' gestation, thyroidectomy was performed and tracheal, arterial and venous catheters inserted. Following a recovery period experiments were performed from 120-145 days to measure changes in lung liquid secretion or its absorption in response to I.V. adrenaline infusion or to introduction of dibuteryl cyclic AMP into lung liquid. The results were compared with those previously obtained in non-thyroidectomized fetuses. 2. Plasma levels of thyroid hormones in non-thyroidectomized fetuses confirmed the pattern found by previous workers. In thyroidectomized fetuses the levels of thyroxine (T4), tri-iodothyronine (T3) and reverse T3 (rT3) were very low except in one fetus which showed biochemical evidence of thyroid regeneration towards the end of gestation. 3. In thyroidectomized fetuses the normal response to adrenaline infusion (diminution of reversal of lung liquid secretion) was profoundly suppressed and very little gestational maturation in this response took place, except in the one fetus with evidence of thyroid regeneration in which a normal reabsorptive response developed in late gestation. 4. In thyroidectomized fetuses, the normal response to dibuteryl cyclic AMP was greatly reduced and its increase with gestation which normally parallels that seen during adrenaline infusion did not take place.

Barker, P M; Brown, M J; Ramsden, C A; Strang, L B; Walters, D V

1988-01-01

243

Effects of catecholamines and cyclic amp on excitation--contraction coupling in isolated skeletal muscle fibres of the frog.  

PubMed Central

1. In skeletal muscle the presence of a positive inotropic effect induced by adrenaline has been a matter of controversy. If it exists, it could be due to catecholamines acting on the actomyosin system, on the sarcoplasmic reticulum (SR) Ca2+ pump or on the release or influx of Ca2+. We investigated these possibilities by using intact, split and skinned skeletal muscle fibres. We also investigated whether adrenaline acts directly or through cyclic AMP. 2. Catecholamines produced an increase in twitch tension and in maximum rates of tension development and tension decay. The inotropic effect took 3 min to appear and 8 min to reach its maximum level. With tetanic stimulations the extra force appeared only at the beginning of the tetanus while approaching the same maximum level, and tended to disappear faster, the higher the frequency of stimulation. At 4 shocks/sec the peak twitch tension with catecholamines decreased during the first seven to ten twitches and became steady afterwards at a level that was still greater than the control. 3. Resting and action potentials showed no important changes in the presence of adrenaline that could explain the inotropic effect. 4. In split fibres the force produced with the release of Ca2+ from the SR by caffeine was 60-100% larger when cyclic AMP was added to the previous loading solution. In skinned fibres adrenaline given directly to the interior of the cell produced no changes in contraction--relaxation cycles induced by fixed amounts of Ca2+ applied with a pipette. 5. These results strongly suggest that catecholamines through cyclic AMP stimulate the SR Ca2+ pump, increasing thereby the concentration of Ca2+ within the SR. This extra Ca2+ when released during subsequent activation may produce the increase in twitch tension.

Gonzalez-Serratos, H; Hill, L; Valle-Aguilera, R

1981-01-01

244

Protein kinase activity-dependent inhibition of urokinase-type plasminogen activator gene transcription by cyclic AMP in human pre-B lymphoma cell line RC-K8  

Microsoft Academic Search

We investigated the effects of cAMP on the urokinase-type plasminogen activator (uPA) production in human pre-B lymphoma cell line RC-K8 that is consistently secreting uPA in the conditioned medium. Both Bt2cAMP and PGE1 inhibited the uPA accumulation in a dose-dependent manner. Northern blot analysis and nuclear run-on assay revealed that uPA gene transcription was repressed by Bt2cAMP and the repression

Masahiro Shinbo; Kenji Niiya; Maher Al-mokdad; Yumiko Hayakawa; Ko-ichi Hiraga; Masao Fujimaki; Nobuo Sakuragawa

1995-01-01

245

Activation of Cyclic AMP Signaling Leads to Different Pathway Alterations in Lesions of the Adrenal Cortex Caused by Germline PRKAR1A Defects versus Those due to Somatic GNAS Mutations  

PubMed Central

Context: The overwhelming majority of benign lesions of the adrenal cortex leading to Cushing syndrome are linked to one or another abnormality of the cAMP or protein kinase pathway. PRKAR1A-inactivating mutations are responsible for primary pigmented nodular adrenocortical disease, whereas somatic GNAS activating mutations cause macronodular disease in the context of McCune-Albright syndrome, ACTH-independent macronodular hyperplasia, and, rarely, cortisol-producing adenomas. Objective and Design: The whole-genome expression profile (WGEP) of normal (pooled) adrenals, PRKAR1A- (3) and GNAS-mutant (3) was studied. Quantitative RT-PCR and Western blot were used to validate WGEP findings. Results: MAPK and p53 signaling pathways were highly overexpressed in all lesions against normal tissue. GNAS-mutant tissues were significantly enriched for extracellular matrix receptor interaction and focal adhesion pathways when compared with PRKAR1A-mutant (fold enrichment 3.5, P < 0.0001 and 2.1, P < 0.002, respectively). NFKB, NFKBIA, and TNFRSF1A were higher in GNAS-mutant tumors (P < 0.05). Genes related to the Wnt signaling pathway (CCND1, CTNNB1, LEF1, LRP5, WISP1, and WNT3) were overexpressed in PRKAR1A-mutant lesions. Conclusion: WGEP analysis revealed that not all cAMP activation is the same: adrenal lesions harboring PRKAR1A or GNAS mutations share the downstream activation of certain oncogenic signals (such as MAPK and some cell cycle genes) but differ substantially in their effects on others.

Almeida, Madson Q.; Azevedo, Monalisa F.; Xekouki, Paraskevi; Bimpaki, Eirini I.; Horvath, Anelia; Collins, Michael T.; Karaviti, Lefkothea P.; Jeha, George S.; Bhattacharyya, Nisan; Cheadle, Chris; Watkins, Tonya; Bourdeau, Isabelle; Nesterova, Maria

2012-01-01

246

Effect of Immunization on the Cyclic AMP Level and 3H-Thymidine Incorporation in Cultured Lymphoid Cells  

Microsoft Academic Search

The cyclic AMP level and the uptake of 3H-thymidine were studied in short-term suspension cultures of guinea pig lymphoid cells. Spleen cells from animals immunized 3 days previously with typhoid vaccine were shown to differ in three respects from the normal cells: (1) The level of cyclic AMP was higher. (2) The cyclic AMP increase following addition of isoproterenol or

G. Sandberg; U. Ernström; K. Nordlind; B. B. Fredholm

1978-01-01

247

Relationship between cyclic AMP-dependent protein tyrosine phosphorylation and extracellular calcium during hyperactivation of boar spermatozoa.  

PubMed

In mammalian spermatozoa, the state of protein tyrosine phosphorylation is modulated by protein tyrosine kinases and protein tyrosine phosphatases that are controlled via cyclic AMP (cAMP)-protein kinase A (PKA) signaling cascades. The aims of this study were to examine the involvement of cAMP-induced protein tyrosine phosphorylation in response to extracellular calcium and to characterize effects of pharmacological modulation of the cAMP-induced protein phosphorylation state and calmodulin activity during hyperactivation in boar spermatozoa. Ejaculated spermatozoa were incubated with cBiMPS (a cell-permeable cAMP analog) and CaCl(2) at 38.5°C to induce hyperactivation, and then used for Western blotting and indirect immunofluorescence of phosphorylated proteins and for the assessment of motility. Both cBiMPS and CaCl(2) were necessary for hyperactivation. The increase in hyperactivated spermatozoa exhibited a dependence on the state of cBiMPS-induced protein tyrosine phosphorylation in the connecting and principal pieces. The addition of calyculin A (an inhibitor for protein phosphatases 1/2A (PP1/PP2A), 50-100 nM) coincidently promoted hyperactivation and cAMP-induced protein tyrosine phosphorylation in the presence of cBiMPS and CaCl(2). Moreover, the addition of W-7 (a calmodulin antagonist, 2-4 µM) enhanced the percentages of hyperactivated spermatozoa after incubation with cBiMPS and CaCl(2), independently of protein tyrosine phosphorylation. These findings indicate that cAMP-induced protein tyrosine phosphorylation in the connecting and principal pieces is involved in hyperactivation in response to extracellular calcium, and that calmodulin may suppress hyperactivation via the signaling cascades that are independent of cAMP-induced protein tyrosine phosphorylation. PMID:22933303

Harayama, Hiroshi; Noda, Taichi; Ishikawa, Shou; Shidara, Osamu

2012-09-14

248

Regulation of cyclic AMP levels in Arthrobacter crystallopoietes and a morphogenetic mutant.  

PubMed Central

The extracellular levels of cyclic AMP (cAMP), cAMP phosphodiesterase activity, and adenylate cyclase activity were measured at various intervals during growth and morphogenesis of Arthrobacter crystallopoietes. There was a significant rise in the extracellular cAMP level at the onset of stationary phase, and this rise coincided with a decrease in intracellular cAMP. The phosphodiesterase activity measured in vitro increased in the early exponential phase of growth as intracellular cAMP decreased, and, conversely, prior to the onset of stationary phase the phosphodiesterase activity decreased as the intracellular cAMP levels increased. Adenylate cyclase activity was greater in cell extracts prepared from cells grown in a medium where morphogenesis was observed. Pyruvate stimulated adenylate cyclase activity in vitro. A morphogenetic mutant, able to grow only as spheres in all media tested, was shown to have altered adenylated cyclase activity, whereas no significant difference compared to the parent strain was detectable in either the phosphodiesterase activity or the levels of extracellular cAMP. The roles of the two enzymes, adenylate cyclase and phosphodiesterase, and excretion of cAMP are discussed with regard to regulation of intracellular cAMP levels and morphogenesis.

Hamilton, R W; Kolenbrander, P E

1978-01-01

249

Cyclic AMP signaling pathway modulates susceptibility of candida species and Saccharomyces cerevisiae to antifungal azoles and other sterol biosynthesis inhibitors.  

PubMed

Azoles are widely used antifungals; however, their efficacy is compromised by fungistatic activity and selection of resistant strains during treatment. Recent studies demonstrated roles for the protein kinase C and calcium signaling pathways in modulating azole activity. Here we explored a role for the signaling pathway mediated by cyclic AMP (cAMP), which is synthesized by the regulated action of adenylate cyclase (encoded by CDC35 in Candida albicans and CYR1 in Saccharomyces cerevisiae) and cyclase-associated protein (encoded by CAP1 and SRV2, respectively). Relative to wild-type strains, C. albicans and S. cerevisiae strains mutated in these genes were hypersusceptible to fluconazole (>4- to >16-fold-decreased 48-h MIC), itraconazole (>8- to >64-fold), or miconazole (16- to >64-fold). Similarly, they were hypersusceptible to terbinafine and fenpropimorph (2- to >16-fold), which, like azoles, inhibit sterol biosynthesis. Addition of cAMP to the medium at least partially reversed the hypersusceptibility of Ca-cdc35 and Sc-cyr1-2 mutants. An inhibitor of mammalian adenylate cyclase, MDL-12330A, was tested in combination with azoles; a synergistic effect was observed against azole-susceptible and -resistant strains of C. albicans and five of six non-C. albicans Candida species. Analysis of cAMP levels after glucose induction in the presence and absence of MDL-12330A confirmed that it acts by inhibiting cAMP synthesis in yeast. RNA analysis suggested that a defect in azole-dependent upregulation of the multidrug transporter gene CDR1 contributes to the hypersusceptibility of the Ca-cdc35 mutant. Our results implicate cAMP signaling in the yeast azole response; compounds similar to MDL-12330A may be useful adjuvants in azole therapy. PMID:14506030

Jain, Pooja; Akula, Indira; Edlind, Thomas

2003-10-01

250

Regulation of luminescence by cyclic AMP in cya-like and crp-like mutants of Vibrio fischeri.  

PubMed Central

Mutants of Vibrio fischeri MJ-1 (wild type) apparently deficient in adenylate cyclase (cya-like) or cyclic AMP receptor protein (crp-like) were isolated and characterized. Compared with MJ-1, the mutants produced low levels of luminescence and luciferase. Addition of cyclic AMP restored wild-type levels of luminescence and luciferase in the cya-like mutant but not in the crp-like mutant. The results are consistent with the hypothesis that in V. fischeri cyclic AMP and cyclic AMP receptor protein are required for induction of the luminescence system.

Dunlap, P V

1989-01-01

251

Cyclic AMP inhibits the proliferation of thyroid carcinoma cell lines through regulation of CDK4 phosphorylation.  

PubMed

How cyclic AMP (cAMP) could positively or negatively regulate G1 phase progression in different cell types or in cancer cells versus normal differentiated counterparts has remained an intriguing question for decades. At variance with the cAMP-dependent mitogenesis of normal thyroid epithelial cells, we show here that cAMP and cAMP-dependent protein kinase activation inhibit S-phase entry in four thyroid carcinoma cell lines that harbor a permanent activation of the Raf/ERK pathway by different oncogenes. Only in Ret/PTC1-positive TPC-1 cells did cAMP markedly inhibit the Raf/ERK cascade, leading to mTOR pathway inhibition, repression of cyclin D1 and p21 and p27 accumulation. p27 knockdown did not prevent the DNA synthesis inhibition. In the other cells, cAMP little affected these signaling cascades and levels of cyclins D or CDK inhibitors. However, cAMP differentially inhibited the pRb-kinase activity and T172-phosphorylation of CDK4 complexed to cyclin D1 or cyclin D3, whereas CDK-activating kinase activity remained unaffected. At variance with current conceptions, our studies in thyroid carcinoma cell lines and previously in normal thyrocytes identify the activating phosphorylation of CDK4 as a common target of opposite cell cycle regulations by cAMP, irrespective of its impact on classical mitogenic signaling cascades and expression of CDK4 regulatory partners. PMID:18799615

Rocha, Ana Sofia; Paternot, Sabine; Coulonval, Katia; Dumont, Jacques E; Soares, Paula; Roger, Pierre P

2008-09-17

252

Cyclic AMP is sufficient for triggering the exocytic recruitment of aquaporin-2 in renal epithelial cells  

PubMed Central

The initial response of renal epithelial cells to the antidiuretic hormone arginine vasopressin (AVP) is an increase in cyclic AMP. By applying immunofluorescence, cell membrane capacitance and transepithelial water flux measurements we show that cAMP alone is sufficient to elicit the antidiuretic cellular response in primary cultured epithelial cells from renal inner medulla, namely the transport of aquaporin-2 (AQP2)-bearing vesicles to, and their subsequent fusion with, the plasma membrane (AQP2 shuttle). The AQP2 shuttle is evoked neither by AVP-independent Ca2+ increases nor by AVP-induced Ca2+ increases. However, clamping cytosolic Ca2+ concentrations below resting levels at 25 nM inhibited exocytosis. Exocytosis was confined to a slow monophasic response, and readily releasable vesicles were missing. Analysis of endocytic capacitance steps revealed that cAMP does not decelerate the retrieval of AQP2 from the plasma membrane. Our data suggest that cAMP initiates an early step, namely the transport of AQP2-bearing vesicles towards the plasma membrane, and do not support a regulatory function for Ca2+ in the AQP2 shuttle.

Lorenz, Dorothea; Krylov, Andrey; Hahm, Daniel; Hagen, Volker; Rosenthal, Walter; Pohl, Peter; Maric, Kenan

2003-01-01

253

Investigation of the subcellular distribution of cyclic-AMP phosphodiesterase in rat hepatocytes, using a rapid immunological procedure for the isolation of plasma membrane.  

PubMed

The distribution of cyclic-AMP phosphodiesterase was investigated in subcellular fractions prepared from homogenates of rat liver or isolated hepatocytes. When measured at 1 mM or 1 microM substrate concentration, approx. 35% or 50%, respectively, of enzyme activity was particulate. The soluble activity appeared to be predominantly a 'high Km' form, whereas the particulate activity had both 'high Km' and 'low Km' components. The recovery of cyclic-AMP phosphodiesterase was measured using 1 microM substrate concentraiton, in plasma membrane-containing fractions prepared either by centrifugation or by the use of specific immunoadsorbents. The recovery of phosphodiesterase was lower than that of marker enzymes for plasma membrane, and comparable with the recovery of markers for intracellular membranes. It was concluded that regulation of both 'high Km' and 'low Km' phosphodiesterase could potentially make a significant contribution to the control of cyclic AMP concentration, even at microM levels, in the liver. the 'low Km' enzyme, for which activation by hormones has been previously described, appears to be located predominantly in intracellular membranes in hepatocytes. The immunological procedure for membrane isolation allowed the rapid preparation of plasma membranes in high yield. Liver cells were incubated with rabbit anti-(rat erythrocyte) serum and homogenized. The antibody-coated membrane fragments were then extracted onto an immunoadsorbent consisting of sheep anti-(rabbit IgG) immunoglobulin covalently bound to aminocellulose. Plasma membrane was obtained in approx. 40% yield within 50 min of homogenizing cells. PMID:218638

Westwood, S A; Luzio, J P; Flockhart, D A; Siddle, K

1979-04-01

254

Cyclic AMP-Dependent Osmoregulation of crp Gene Expression in Escherichia coli  

PubMed Central

We have found that the cyclic AMP (cAMP) receptor protein (CRP)-cAMP regulatory complex in Escherichia coli is subject to osmoregulation at the level of crp gene expression. This osmoregulation was lost in a cya mutant strain but could be restored by external addition of cAMP, suggesting that the intracellular level of cAMP is a key factor in the osmoregulation of CRP. The ability of the cell to maintain optimal CRP activity was essential for the growth and survival of the bacteria under low-osmolarity conditions as shown by studies with different crp mutant alleles. A suppressor mutant with a novel amino acid substitution (L124R) in CRP showed restored growth at low osmolarity. CRP(L124R) was not activated by cAMP and was shown to be dominant negative over the wild type. Our findings suggest that the fine-tuning of the CRP activity may be critical for bacterial viability and adaptability to changing osmotic conditions.

Balsalobre, Carlos; Johansson, Jorgen; Uhlin, Bernt Eric

2006-01-01

255

Modulation of F-actin rearrangement by the cyclic AMP/cAMP-dependent protein kinase (PKA) pathway is mediated by MAPK-activated protein kinase 5 and requires PKA-induced nuclear export of MK5.  

PubMed

The MAPK-activated protein kinases belong to the Ca2+/calmodulin-dependent protein kinases. Within this group, MK2, MK3, and MK5 constitute three structurally related enzymes with distinct functions. Few genuine substrates for MK5 have been identified, and the only known biological role is in ras-induced senescence and in tumor suppression. Here we demonstrate that activation of cAMP-dependent protein kinase (PKA) or ectopic expression of the catalytic subunit Calpha in PC12 cells results in transient nuclear export of MK5, which requires the kinase activity of both Calpha and MK5 and the ability of Calpha to enter the nucleus. Calpha and MK5, but not MK2, interact in vivo, and Calpha increases the kinase activity of MK5. Moreover, Calpha augments MK5 phosphorylation, but not MK2, whereas MK5 does not seem to phosphorylate Calpha. Activation of PKA can induce actin filament accumulation at the plasma membrane and formation of actin-based filopodia. We demonstrate that small interfering RNA-triggered depletion of MK5 interferes with PKA-induced F-actin rearrangement. Moreover, cytoplasmic expression of an activated MK5 variant is sufficient to mimic PKA-provoked F-actin remodeling. Our results describe a novel interaction between the PKA pathway and MAPK signaling cascades and suggest that MK5, but not MK2, is implicated in PKA-induced microfilament rearrangement. PMID:17947239

Gerits, Nancy; Mikalsen, Theresa; Kostenko, Sergiy; Shiryaev, Alexey; Johannessen, Mona; Moens, Ugo

2007-10-17

256

Possible role of cyclic AMP phosphodiesterases in the actions of ibudilast on eosinophil thromboxane generation and airways smooth muscle tone.  

PubMed

1. The possible role of cyclic AMP phosphodiesterase (PDE) in the inhibitory actions of ibudilast on tracheal smooth muscle contractility and eosinophil thromboxane generation was investigated. 2. Ibudilast was a non-selective inhibitor of partially purified cyclic nucleotide PDE isoenzymes from pig aorta and bovine tracheal smooth muscle, exhibiting only moderate potency against bovine tracheal PDE IV (IC50 = 12 +/- 4 microM, n = 3). Similar or slightly lower potencies were displayed against PDEs I, II, III and V. In contrast, rolipram exhibited selectivity for PDE IV (3 +/- 0.5 microM, n = 3). 3. Ibudilast (IC50 = 0.87 +/- 0.37 microM, n = 3), like rolipram (IC50 = 0.20 +/- 0.04 microM, n = 3), was a more potent inhibitor of membrane-bound PDE IV from guinea-pig eosinophils than of partially purified PDE IV from bovine tracheal smooth muscle. The potency of ibudilast increased when the eosinophil enzyme was solubilised with deoxycholate and NaCl (IC50 = 0.11 +/- 0.05 microM, n = 3) or exposed to vanadate/glutathione complex (V/GSH) (IC50 = 0.11 +/- 0.02 microM, n = 3). The potency of rolipram was also increased by solubilization (IC50 = 0.012 +/- 0.003, n = 3) or V/GSH (IC50 = 0.012 +/- 0.003, n = 3). 4. In intact eosinophils, ibudilast (0.032 microM-20 microM) potentiated isoprenaline-induced cyclic AMP accumulation in a concentration-dependent manner, being approximately 20 fold less potent than rolipram. Little or no effect on basal cyclic AMP levels was observed with either compound. The cyclicAMP-dependent protein kinase activity ratio was significantly increased following incubation of eosinophils with either ibudilast (20 MicroM) or rolipram (20 MicroM) in the absence or presence of isoprenaline.5. Leukotriene B4 (300 nM)-induced thromboxane generation from guinea-pig eosinophils was inhibited by ibudilast (IC50 = 11.3 +/- 3.7 MicroM, n = 5) and rolipram (IC50 = 0.280 +/- 0.067 MicroM, n = 5) in a concentration-dependent manner.6. Ibudilast (10 nM-1 MicroM), whilst generally less potent than rolipram (1 nM- 1 MicroM), produced concentration-dependent relaxation of spasmogen (methacholine, histamine, LTD4)-induced tone in the guinea pig isolated tracheal strip. Ibudilast was less potent in reversing the methacholine (IC50 = 1.95 +/- 0.40 JM,n =6)-induced contraction than those of histamine (IC50 = 0.18 +/- 0.70 MicroM, n =6) or leukotriene D4(LTD4, IC50 = 0.12 +/- 0.05 MicroM, n = 6). Rolipram also exhibited a similar pattern of activity, although the difference in potency against methacholine (IC50 = 0.1 +/- 0.01 MicroM, n = 6) compared with the other two spasmogens, histamine (IC50 = 0.034 +/- 0.017 MicroM, n = 7) and LTD4 (IC50 = 0.026 +/- 0.008 MicroM, n = 7), was not as great.7. These results demonstrate that ibudilast, like rolipram, has several biological actions on the eosinophil and airways smooth muscle which may be attributed to inhibition of cyclic AMP PDE. These actions may account, at least in part, for the recently reported anti-asthma effects of ibudilast. PMID:8032594

Souness, J E; Villamil, M E; Scott, L C; Tomkinson, A; Giembycz, M A; Raeburn, D

1994-04-01

257

Differences in the adenosine receptors modulating inositol phosphates and cyclic AMP accumulation in mammalian cerebral cortex.  

PubMed Central

1. 2-Chloroadenosine stimulated adenosine 3':5'-cyclic monophosphate (cyclic AMP) accumulation and potentiated (guinea-pig) or inhibited (mouse) the histamine H1-receptor-stimulated hydrolysis of inositol phospholipids in slices of guinea-pig and mouse cerebral cortex. 2. Two xanthine-based adenosine receptor antagonists were identified which were one order of magnitude more potent at the adenosine receptor mediating augmentation of the histamine-stimulated inositol phospholipid hydrolysis than at the receptor linked to cyclic AMP formation in guinea-pig cerebral cortical slices. 3. These compounds, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and 7-benzyl-3-(2-methylpropyl)xanthine (BMPX) retained their selectivity under near-identical incubation conditions in both assays. 4. These compounds also showed similar affinities and selectivity for the adenosine receptor mediating inhibition of histamine-stimulated inositol phospholipid hydrolysis in mouse cerebral cortical slices. 5. Inclusion of agents which give rise to, or mimic, high levels of cyclic AMP (forskolin (1 microM), 8-bromo-cyclic AMP (1 mM) and vasoactive intestinal polypeptide (1 microM] in the incubation medium failed to mimic the action of 2-chloroadenosine on inositol phospholipid turnover in cerebral cortical slices from either species. 6. These data suggest that the adenosine receptor modulating the hydrolysis of inositol phospholipid in mouse and guinea-pig cerebral cortical slices is different from the adenosine receptor linked to cyclic AMP formation, and, furthermore, that the modulation of inositol phospholipid metabolism in either species is not mediated via alterations in cyclic AMP levels.

Alexander, S. P.; Kendall, D. A.; Hill, S. J.

1989-01-01

258

Cyclic AMP regulation of early gene expression in Dictyostelium discoideum: mediation via the cell surface cyclic AMP receptor.  

PubMed Central

We examined two sets of genes expressed early in the developmental cycle of Dictyostelium discoideum that appear to be regulated by cyclic AMP (cAMP). The transcripts of both sets of genes were not detectable in vegetative cells. During normal development on filter pads, RNA complementary to these genes could be detected at about 2 h, peaked around 6 to 8 h, and decreased gradually thereafter. Expression of these genes upon starvation in shaking culture was stimulated by pulsing the cells with nanomolar levels of cAMP, a condition that mimics the in vivo pulsing during normal aggregation. Expression was inhibited by caffeine or by continuous levels of cAMP, a condition found later in development when in vivo expression of these genes decreased. The inhibition of caffeine could be overcome by pulsing cells with cAMP. These results suggest that the expression is mediated via the cell surface cAMP receptor, but does not require a rise in intracellular cAMP. mRNA from a gene of the second class was induced upon starvation, peaked by 2.5 h of development, and then declined. In contrast to the other genes, its expression was maintained by continuous levels of cAMP and repressed by cAMP pulses. These and other results on a number of classes of developmentally regulated genes indicates that changing levels of cAMP, acting via the cell surface cAMP receptor, are involved in controlling these groups of genes. We also examined the structure and partial sequence of the cAMP pulse-induced genes. The two tandemly duplicated M3 genes were almost continuously homologous over the sequenced portion of the protein-coding region except for a region near the N-terminal end. The two M3 genes had regions of homology in the 5' flanking sequence and showed slight homology to the same regions in gene D2, another cAMP pulse-induced gene. D2 showed extremely significant homology over its entire sequenced length to an acetylcholinesterase. The results presented here and by others suggest that expression of many early genes in D. discoideum is regulated via the cell surface cAMP receptor. We expect that many of these genes may play essential roles in early Dictyostelium development and could code for elements of the cAMP signal transduction pathway involved in aggregation. Images

Mann, S K; Firtel, R A

1987-01-01

259

Potent constitutive cyclic AMP-generating activity of XL?s implicates this imprinted GNAS product in the pathogenesis of McCune-Albright Syndrome and fibrous dysplasia of bone  

PubMed Central

Patients with McCune-Albright syndrome (MAS), characterized primarily by hyperpigmented skin lesions, precocious puberty, and fibrous dyslasia of bone, carry postzygotic heterozygous mutations of GNAS causing constitutive cAMP signaling. GNAS encodes the ?-subunit of the stimulatory G protein (Gs?), as well as a large variant (XL?s) derived from the paternal allele. The mutations causing MAS affect both GNAS products, but whether XL?s, like Gs?, can be involved in the pathogenesis remains unknown. Here, we investigated biopsy samples from four previously reported and eight new patients with MAS. Activating mutations of GNAS (Arg201 with respect to the amino acid sequence of Gs?) were present in all the previously reported and five of the new cases. The mutation was detected within the paternally expressed XL?s transcript in five and the maternally expressed NESP55 transcript in four cases. Tissues carrying paternal mutations appeared to have higher XL?s mRNA levels than maternal mutations. The human XL?s mutant analogous to Gs?-R201H (XL?s-R543H) showed markedly higher basal cAMP accumulation than wild-type XL?s in transfected cells. Wild-type XL?s demonstrated higher basal and isoproterenol-induced cAMP signaling than Gs? and co-purified with G?1?2 in transduced cells. XL?s mRNA was measurable in mouse calvarial cells, with its level being significantly higher in undifferentiated cells than those expressing preosteoblastic markers osterix and alkaline phosphatase. XL?s mRNA was also expressed in murine bone marrow stromal cells and preosteoblastic MC3T3-E1 cells. Our findings are consistent with the possibility that constitutive XL?s activity adds to the molecular pathogenesis of MAS and fibrous dysplasia of bone.

Mariot, Virginie; Wu, Joy Y.; Aydin, Cumhur; Mantovani, Giovanna; Mahon, Matthew J.; Linglart, Agnes; Bastepe, Murat

2010-01-01

260

Thermal denaturation of the apo-cyclic AMP receptor protein and noncovalent interactions between its domains.  

PubMed

Cyclic AMP receptor protein (CRP) is allosterically activated by cAMP and functions as a global transcription regulator in enteric bacteria. Structural information on CRP in the absence of cAMP (apo-CRP) is essential to fully understand its allosteric behavior. In this study we demonstrated interdomain interactions in apo-CRP, using a comparative thermodynamic approach to the intact protein and its isolated domains, which were prepared either by limited proteolysis or using recombinant DNA. Thermal denaturation of the intact apo-CRP, monitored by differential scanning calorimetry, revealed an apparently single cooperative transition with a slight asymmetry. Combined with circular dichroism and fluorescence analysis, the thermal denaturation of apo-CRP could be interpreted as a coupled process involving two individual transitions, each attributable to a structural domain. When isolated individually, both of the domains exhibited significantly altered thermal behavior, thus pointing to the existence of non-covalent interdomain interactions in the intact apo-CRP. These observations suggest that the allosteric conformational change of CRP upon binding to cAMP is achieved by perturbing or modifying pre-existing interdomain interactions. They also underline the effectiveness of a comparative approach using calorimetric and structural probes for studying the thermodynamics of a protein. PMID:18525238

Won, Hyung-Sik; Seo, Min-Duk; Ko, Hyun-Suk; Choi, Wahn Soo; Lee, Bong-Jin

2008-06-04

261

Up-regulation of low-threshold tetrodotoxin-resistant Na+ current via activation of a cyclic AMP/protein kinase A pathway in nociceptor-like rat dorsal root ganglion cells.  

PubMed

The effects of forskolin on low-threshold tetrodotoxin-resistant (TTX-r) Na(+) currents was studied in small diameter (average ? 25 ?m) dorsal root ganglion (DRG) cells. All DRG cells included in the study were categorized as type-2 or non-type-2 based on the expression of a low-threshold A-current. In all type-2 and some non-type-2 DRG cells held at -80 mV, the adenylyl cyclase (AC) activator forskolin (10 ?M) up-regulated TTX-r Na(+) currents evoked with steps to -55 mV through -35 mV (low-threshold current). Up-regulation of low-threshold current by forskolin was mimicked by the protein kinase A (PKA) agonist Sp-cAMPs and the inflammatory mediator serotonin, and blocked by the PKA antagonist Rp-cAMPs. Forskolin-induced up-regulation of low-threshold current evoked from a holding potential of -60 mV was blocked by 40 ms steps to 0 mV, which presumably induced a long lasting inactivation of the low-threshold channels. Reducing to 3 ms the duration of steps to 0 mV, significantly increased the number of DRG cells where low-threshold current was up-regulated by forskolin, presumably by reducing the long-lasting inactivation of the low-threshold channels. In the same cells, high-threshold current, evoked by 40 ms or 3 ms steps to 0 mV, was consistently up-regulated by forskolin. The selective Na(V)1.8 channel blocker A-803467 markedly blocked high-threshold current but not low-threshold current. The different voltage protocols observed to activate and inactivate the low- and high-threshold currents, and the observation that A-803467 blocked high- but not low-threshold current suggests that the two currents were mediated by different channels, possibly Na(V)1.8 and Na(V)1.9, respectively. Inflammatory mediators may simultaneously up-regulate Na(V)1.8 and Na(V)1.9 channels in the same nociceptor via a AC/PKA signaling pathway, increasing nociceptor signaling strength, and lowering nociceptor threshold, respectively. PMID:21549179

Scroggs, R S

2011-04-28

262

Trafficking and Gating of Hyperpolarization-activated Cyclic Nucleotide-gated Channels Are Regulated by Interaction with Tetratricopeptide Repeat-containing Rab8b-interacting Protein (TRIP8b) and Cyclic AMP at Distinct Sites*  

PubMed Central

Ion channel trafficking and gating are often influenced by interactions with auxiliary subunits. Tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) is an auxiliary subunit for neuronal hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. TRIP8b interacts directly with two distinct sites of HCN channel pore-forming subunits to control channel trafficking and gating. Here we use mutagenesis combined with electrophysiological studies to define and distinguish the functional importance of the HCN/TRIP8b interaction sites. Interaction with the last three amino acids of the HCN1 C terminus governed the effect of TRIP8b on channel trafficking, whereas TRIP8b interaction with the HCN1 cyclic nucleotide binding domain (CNBD) affected trafficking and gating. Biochemical studies revealed that direct interaction between TRIP8b and the HCN1 CNBD was disrupted by cAMP and that TRIP8b binding to the CNBD required an arginine residue also necessary for cAMP binding. In accord, increasing cAMP levels in cells antagonized the up-regulation of HCN1 channels mediated by a TRIP8b construct binding the CNBD exclusively. These data illustrate the distinct roles of the two TRIP8b-HCN interaction domains and suggest that TRIP8b and cAMP may directly compete for binding the HCN CNBD to control HCN channel gating, kinetics, and trafficking.

Han, Ye; Noam, Yoav; Lewis, Alan S.; Gallagher, Johnie J.; Wadman, Wytse J.; Baram, Tallie Z.; Chetkovich, Dane M.

2011-01-01

263

Trafficking and gating of hyperpolarization-activated cyclic nucleotide-gated channels are regulated by interaction with tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) and cyclic AMP at distinct sites.  

PubMed

Ion channel trafficking and gating are often influenced by interactions with auxiliary subunits. Tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) is an auxiliary subunit for neuronal hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. TRIP8b interacts directly with two distinct sites of HCN channel pore-forming subunits to control channel trafficking and gating. Here we use mutagenesis combined with electrophysiological studies to define and distinguish the functional importance of the HCN/TRIP8b interaction sites. Interaction with the last three amino acids of the HCN1 C terminus governed the effect of TRIP8b on channel trafficking, whereas TRIP8b interaction with the HCN1 cyclic nucleotide binding domain (CNBD) affected trafficking and gating. Biochemical studies revealed that direct interaction between TRIP8b and the HCN1 CNBD was disrupted by cAMP and that TRIP8b binding to the CNBD required an arginine residue also necessary for cAMP binding. In accord, increasing cAMP levels in cells antagonized the up-regulation of HCN1 channels mediated by a TRIP8b construct binding the CNBD exclusively. These data illustrate the distinct roles of the two TRIP8b-HCN interaction domains and suggest that TRIP8b and cAMP may directly compete for binding the HCN CNBD to control HCN channel gating, kinetics, and trafficking. PMID:21504900

Han, Ye; Noam, Yoav; Lewis, Alan S; Gallagher, Johnie J; Wadman, Wytse J; Baram, Tallie Z; Chetkovich, Dane M

2011-04-19

264

Cyclic nucleotides of cone-dominant retinas. Reduction of cyclic AMP levels by light and by cone degeneration.  

PubMed

Dark-adapted retinas or whole eyes of 13-line ground squirrels (Citellus tridecemlineatus) and western fence lizards (Sceloporus occidentalis) contain higher levels of cyclic AMP than of cyclic GMP. In these cone-dominant retinas, light reduces cyclic AMP content selectively. Freezing of dark- or light-adapted retinas or eyes also reduces cyclic AMP content, with only minimal changes in cyclic GMP levels. In addition, exposure of frozen retinas of dark-adapted ground squirrel to light results in a significant decrease in cyclic AMP content. The destruction of cone visual cells of ground squirrel retina by iodoacetic acid injection decreases the cyclic nucleotide content of the dark-adapted retina. Considering the relative loss of cyclic nucleotides from cone degeneration, we estimate that the content of cyclic AMP in visual cells of ground squirrel retina is about four times greater than that of cyclic GMP. PMID:6256308

Farber, D B; Souza, D W; Chase, D G; Lolley, R N

1981-01-01

265

Cyclic AMP-elevating agents down-regulate the oxidative burst induced by granulocyte-macrophage colony-stimulating factor (GM-CSF) in adherent neutrophils.  

PubMed Central

Human neutrophils, plated on fibronectin-precoated wells, were found to release large quantities of superoxide anion (O2-) in response to GM-CSF. O2- production was reduced by prostaglandin E2 (PGE2) and the phosphodiesterase type IV (PDE IV) inhibitor RO 20-1724. Both agents are known to increase intracellular cyclic AMP (cAMP) levels by inducing its production (PGE2) or blocking its catabolism (RO 20-1724). When added in combination, PGE2 and RO 20-1724 had a marked synergistic inhibitory effect, which was reproduced by replacing PGE2 with a direct activator of adenylate cyclase, i.e. forskolin (FK). Moreover, the neutrophil response to GM-CSF was inhibited by a membrane-permeable analogue of cAMP in a dose-dependent manner. As GM-CSF and PGE2 are known to be generated at tissue sites of inflammation, the results suggest the existence of a PGE2-dependent regulatory pathway potentially capable of controlling the neutrophil response to GM-CSF, in turn limiting the risk of local oxidative tissue injury. Moreover, owing to its susceptibility to amplification by RO 20-1724, the PGE2-dependent pathway and in particular PDE-IV may represent a pharmacological target to reduce the generation of histotoxic oxidants by GM-CSF-responding neutrophils.

Ottonello, L; Morone, M P; Dapino, P; Dallegri, F

1995-01-01

266

Cyclic AMP Receptor Protein Regulates Pheromone-Mediated Bioluminescence at Multiple Levels in Vibrio fischeri ES114.  

PubMed

Bioluminescence in Vibrio fischeri ES114 is activated by autoinducer pheromones, and this regulation serves as a model for bacterial cell-cell signaling. As in other bacteria, pheromone concentration increases with cell density; however, pheromone synthesis and perception are also modulated in response to environmental stimuli. Previous studies suggested that expression of the pheromone-dependent bioluminescence activator LuxR is regulated in response to glucose by cyclic AMP (cAMP) receptor protein (CRP) (P. V. Dunlap and E. P. Greenberg, J. Bacteriol. 164:45-50, 1985; P. V. Dunlap and E. P. Greenberg, J. Bacteriol. 170:4040-4046, 1988; P. V. Dunlap, J. Bacteriol. 171:1199-1202, 1989; and W. F. Friedrich and E. P. Greenberg, Arch. Microbiol. 134:87-91, 1983). Consistent with this model, we found that bioluminescence in V. fischeri ES114 is modulated by glucose and stimulated by cAMP. In addition, a ?crp mutant was ?100-fold dimmer than ES114 and did not increase luminescence in response to added cAMP, even though cells lacking crp were still metabolically capable of producing luminescence. We further discovered that CRP regulates not only luxR but also the alternative pheromone synthase gene ainS. We found that His-tagged V. fischeri CRP could bind sequences upstream of both luxR and ainS, supporting bioinformatic predictions of direct regulation at both promoters. Luminescence increased in response to cAMP if either the ainS or luxR system was under native regulation, suggesting cAMP-CRP significantly increases luminescence through both systems. Finally, using transcriptional reporters in transgenic Escherichia coli, we elucidated two additional regulatory connections. First, LuxR-independent basal transcription of the luxI promoter was enhanced by CRP. Second, the effect of CRP on the ainS promoter depended on whether the V. fischeri regulatory gene litR was also introduced. These results suggest an integral role for CRP in pheromone signaling that goes beyond sensing cell density. PMID:23995643

Lyell, Noreen L; Colton, Deanna M; Bose, Jeffrey L; Tumen-Velasquez, Melissa P; Kimbrough, John H; Stabb, Eric V

2013-08-30

267

Cyclic AMP stimulation of calcium efflux from kidney, liver, and heart mitochondria  

Microsoft Academic Search

Summary The effect of cyclic AMP on subcellular calcium turnover was studied in isolated kidney, liver and heart mitochondria. The calcium concentration of the incubating medium was determined by fluorometric methods after its separation by millipore filtration. Liver and kidney mitochondria take up calcium in exchange for H+ and lower the medium calcium to 1 to 40×10-6m in less than

André B. Borle

1974-01-01

268

Lysophosphatidic acid mimics serum-induced sensitization of cyclic AMP accumulation  

Microsoft Academic Search

Pretreatment of 1321N1 human astrocytoma cells with serum induces a pronounced increase in subse- quent stimulation by forskolin and other agents of in- tracellular cyclic AMP accumulation, a phenomenon referred to as sensitization (Mol. Pharmacol. 39, 399-406, 1991). Pretreatment of these cells with lysophosphatidic acid induced sensitization to a similar extent as that with serum (approximately fivefold for for- skolin

DANA M. KREPS; SARA M. WHIrrLE; JOANNE M. HOFFMAN; MYRON L. TOEWS

269

The myriad roles of cyclic AMP in microbial pathogens: from signal to sword  

Microsoft Academic Search

All organisms must sense and respond to their external environments, and this signal transduction often involves second messengers such as cyclic nucleotides. One such nucleotide is cyclic AMP, a universal second messenger that is used by diverse forms of life, including mammals, fungi, protozoa and bacteria. In this review, we discuss the many roles of cAMP in bacterial, fungal and

Ana Rodriguez; Kathleen A. McDonough

2011-01-01

270

Cyclic AMP-independent secretion of mucin by SW1116 human colon carcinoma cells. Differential control by Ca2+ ionophore A23187 and arachidonic acid.  

PubMed Central

The regulation of mucin secretion by SW1116 human colon carcinoma cells has been studied using monoclonal antibody 19-9, which has previously been used to detect mucin in the serum of cancer and cystic fibrosis patients. We found that SW1116 cells constitutively secrete considerable amounts of mucin as the predominant glycoprotein. The secretion of mucin by these cells is independent of cyclic AMP levels, but can be further stimulated by the Ca2+ ionophore A23187. However, arachidonic acid and its metabolites inhibit mucin secretion. Electron microscope studies reveal that the mucin is located near the plasma membrane as well as in vesicular and lysosome-like structures. However, the secretion pathway of mucin is different than that of the lysosomal contents, since arachidonic acid, while inhibiting mucin secretion, actually activates the secretion of the lysosomal enzyme beta-glucuronidase. We suggest that the mechanism of mucin secretion by SW1116 cells occurs by a pathway different from common exocytosis, and possibly by more than one pathway. The response of mucin secretion by SW1116 cells to common secretagogues resembles that of epithelial cells obtained from cystic fibrosis patients. Thus SW1116 cells are an especially interesting system for studying processes related to pathological states associated with excessive constitutive secretion of mucin. Images Fig. 2.

Yedgar, S; Eidelman, O; Malden, E; Roberts, D; Etcheberrigaray, R; Goping, G; Fox, C; Pollard, H B

1992-01-01

271

Cyclic AMP-modulated phosphorylation of intermediate filament proteins in cultured avian myogenic cells.  

PubMed Central

The intermediate filament proteins desmin and vimentin and the muscle tropomyosins were the major protein phosphate acceptors in 8-day-old myotubes incubated for 4 h in medium containing radiolabeled phosphate. The addition of isoproterenol or 8-bromo-cyclic AMP (BrcAMP) resulted in a two- to threefold increase in incorporation of 32PO4 into both desmin and vimentin, whereas no changes in the incorporation of 32PO4 into tropomyosin or other cellular proteins were observed. The BrcAMP- or hormonally induced increase in 32PO4 incorporation into desmin and vimentin was independent of protein synthesis and was not caused by stimulation of protein phosphate turnover. In addition, BrcAMP did not induce significant changes in the specific activity of the cellular ATP pool. These data suggest that the observed increase in 32PO4 incorporation represented an actual increase in phosphorylation of the intermediate filament proteins desmin and vimentin. Two-dimensional tryptic analysis of desmin from 8-day-old myotubes revealed five phosphopeptides of which two showed a 7- to 10-fold increase in 32PO4 incorporation in BrcAMP-treated myotubes. Four of the phosphopeptides identified in desmin labeled in vivo were also observed in desmin phosphorylated in vitro by bovine heart cAMP-dependent protein kinase. Although phosphorylation of desmin and vimentin was apparent in myogenic cells at all stages of differentiation, BrcAMP- and isoproterenol-induced increases in phosphorylation of these proteins were restricted to mature myotubes. These data strongly suggest that in vivo phosphorylation of the intermediate filament proteins desmin and vimentin is catalyzed by the cAMP-dependent protein kinases and that such phosphorylation may be regulated during muscle differentiation. Images

Gard, D L; Lazarides, E

1982-01-01

272

Evidence for different interactions between beta(1)- and beta(2)-adrenoceptor subtypes with adenylyl cyclase in the rat brain: a concentration-response study using forskolin.  

PubMed

The aim of this study was to investigate beta(1)- and beta(2)-adrenoceptor signalling systems in the rat brain studying the synergistic effects between beta-adrenoceptor agonists and forskolin- induced activation of adenylyl cyclase. Experiments were performed in slices from cerebral cortex and cerebellum because they contain mainly beta(1)- and almost exclusively beta(2)- adrenoceptors, respectively. Five beta-adrenergic agonists were used, clenbuterol, flerobuterol, isoproterenol, salbutamol, and tulobuterol. All agonists stimulated cyclic AMP accumulation in the cerebral cortex but flerobuterol was inactive in the cerebellum. Forskolin amplified the generation of cyclic AMP. Forskolin potentiation was observed in glial cells but not in neurons and was not dependent on the number of beta-adrenoceptors. In return the amplitude of the potentiation was highly dependent on the intrinsic activity of the agonist in the cerebral cortex whereas it was constant whatever the agonist tested in the cerebellum. To analyse this difference we developed a modelling approach using a concentration-response study. Isoproterenol and forskolin stimulations of cyclic AMP production were studied either alone or in combination with increasing concentrations of forskolin and isoproterenol, respectively. In the cerebral cortex isoproterenol and forskolin were both able to potentiate the cyclic AMP accumulation induced by the other compound, whereas, in the cerebellum, isoproterenol was unable to increase the stimulation induced by forskolin. The results support the hypothesis that beta(1)- and beta(2)-adrenoceptors display distinct mechanisms of action in the signalling system by which they stimulate the accumulation of cyclic AMP. PMID:10704268

Morin, D; Sapena, R; Tillement, J P; Urien, S

2000-04-01

273

Cyclic AMP control measured in two compartments in HEK293 cells: phosphodiesterase K(M) is more important than phosphodiesterase localization.  

PubMed

The intracellular second messenger cyclic AMP (cAMP) is degraded by phosphodiesterases (PDE). The knowledge of individual families and subtypes of PDEs is considerable, but how the different PDEs collaborate in the cell to control a cAMP signal is still not fully understood. In order to investigate compartmentalized cAMP signaling, we have generated a membrane-targeted variant of the cAMP Bioluminiscence Resonance Energy Transfer (BRET) sensor CAMYEL and have compared intracellular cAMP measurements with it to measurements with the cytosolic BRET sensor CAMYEL in HEK293 cells. With these sensors we observed a slightly higher cAMP response to adenylyl cyclase activation at the plasma membrane compared to the cytosol, which is in accordance with earlier results from Fluorescence Resonance Energy Transfer (FRET) sensors. We have analyzed PDE activity in fractionated lysates from HEK293 cells using selective PDE inhibitors and have identified PDE3 and PDE10A as the major membrane-bound PDEs and PDE4 as the major cytosolic PDE. Inhibition of membrane-bound or cytosolic PDEs can potentiate the cAMP response to adenylyl cyclase activation, but we see no significant difference between the potentiation of the cAMP response at the plasma membrane and in cytosol when membrane-bound and cytosolic PDEs are inhibited. When different levels of stimulation were tested, we found that PDEs 3 and 10 are mainly responsible for cAMP degradation at low intracellular cAMP concentrations, whereas PDE4 is more important for control of cAMP at higher concentrations. PMID:21931705

Matthiesen, Karina; Nielsen, Jacob

2011-09-08

274

From Drought Sensing to Developmental Control: Evolution of Cyclic AMP Signaling in Social Amoebas  

Microsoft Academic Search

Amoebas and other protists commonly encyst when faced with environmental stress. Although little is known of the signaling pathways that mediate encystation, the analogous process of spore formation in dictyostelid social amoebas is better understood. In Dictyostelium discoideum, secreted cyclic AMP (cAMP) mediates the aggregation of starving amoebas and induces the differentiation of prespore cells. Intracellular cAMP acting on cAMP-dependent

Allyson V. Ritchie; Saskia van Es; Celine Fouquet; Pauline Schaap

2008-01-01

275

Prevention of methamphetamine-induced behavioral sensitization in rats by a cyclic AMP phosphodiesterase inhibitor, rolipram  

Microsoft Academic Search

Effects of an interaction between rolipram, a cyclic adenosine 3?,5?-monophosphate (cyclic AMP) phosphodiesterase inhibitor, and methamphetamine on the development of behavioral sensitization were observed in rats. In vivo microdialysis showed that a single dose of 4 mg\\/kg methamphetamine (i.p.) significantly increased striatal dopamine levels while coadministration with 4 mg\\/kg rolipram (i.p.) did not affect these levels. Also, methamphetamine alone did

Masaomi Iyo; Ying Bi; Kenji Hashimoto; Toshiya Inada; Susumu Fukui

1996-01-01

276

Production, Uptake, and Metabolic Effects of Cyclic AMP in the Bivascularly Perfused Rat Liver  

Microsoft Academic Search

Production, uptake, and metabolic effects of cyclic AMP (cAMP) were measured in the bivascularly perfused rat liver in anterograde and retrograde perfusion. Glucagon, cAMP, N6,2?-O-dibutyryl cAMP and N6-monobutyryl cAMP were infused into the portal vein (anterograde perfusion), the hepatic vein (retrograde perfusion), or the hepatic artery (anterograde and retrograde perfusion) in order to reach different cell populations. The following results

Jorgete Constantin; Fumie Suzuki-Kemmelmeier; Nair Seiko Yamamoto; Adelar Bracht

1997-01-01

277

Transport of cyclic AMP and synthetic analogs in the perfused rat liver  

Microsoft Academic Search

The purpose of the present work was to investigate the transport of cyclic AMP (cAMP) and analogs in the rat liver. The experimental system was the isolated once-through perfused liver. Transport was measured by employing the multiple-indicator dilution technique. The single-pass recovery of tracer [32P]cAMP was equal to 94.4 ± 1.4%; no significant extracellular transformation of cAMP occurred during a

Geraldo Em??lio Vicentini; Jorgete Constantin; Carlos Henrique Lopez; Adelar Bracht

2000-01-01

278

Prostaglandin-like substances in Propionibacterium acnes II. Stimulatory effect on ovarian cyclic AMP  

Microsoft Academic Search

Summary The prostaglandin-like substances (PLS) fromPropionibacterium acnes increased the ovarian tissue levels of cyclic AMP (cAMP) approximately 2-fold. The lipid material extracted fromP. acnes thus behaved like PG's of the E-type, and since it is unlikely that other known stimulators of the ovarian cAMP system can be present in the bacterial lipid fraction, these experiments give further evidence in favour

L. Hellgren; G. Selstam; J. Vincent

1979-01-01

279

3',5'-cyclic AMP binds to and promotes polymerisation on platelet tubulin  

Microsoft Academic Search

IN spite of considerable research, the regulatory mechanism of the reversible assembly-disassembly of microtubules remains obscure. Of the various processes and agents which have been examined as potential regulators probably none has received as much attention as cyclic nucleotides. Indeed, the number of reports which indicate that adenosine 3',5'-cyclic monophosphate (cyclic AMP) exerts a stimulatory effect in the formation of

Manfred Steiner

1978-01-01

280

3':5'Cyclic AMP and Hormonal Control of Puparium Formation in the Fleshfly Sarcophaga bullata  

Microsoft Academic Search

Injection of 3':5'-cyclic AMP (cAMP) into larvae of the fly Sarcophaga bullata 3-4 hr before the beginning of puparium formation (red-spiracle stage) greatly accelerates the onset of tanning without affecting initiation of puparium formation (anterior retraction). Accelerated tanning resembles real tanning in two important respects: the solubility of cuticular proteins becomes reduced and [U-14C]tyrosine is incorporated into the cuticle. Of

G. Fraenkel; Ann Blechl; James Blechl; Paul Herman; Morris I. Seligman

1977-01-01

281

The effects of forskolin on cyclic AMP, intraocular pressure and aqueous humor formation in rabbits.  

PubMed

Forskolin was used to study cyclic AMP-mediated regulation of aqueous humor dynamics in rabbits. Crystalline forskolin was solubilized in oil and its pharmacological effects were studied both in vitro and following topical ocular administration. In vitro, using cultured corneal epithelial cells, forskolin rapidly stimulated cyclic AMP production and in vivo increased cyclic AMP concentration in the aqueous humor 10-fold following topical administration. The effect of topical forskolin on intraocular pressure and aqueous humor formation was determined in vivo using pneumatonometry and fluorophotometry, respectively. Forskolin caused a prolonged reduction of intraocular pressure and decreased aqueous humor formation. The ability of forskolin to potentiate the ocular hypotensive effect of epinephrine was investigated. Forskolin in combination with epinephrine caused a decrease in intraocular pressure of longer duration than either 0.1% epinephrine or 1% forskolin administered separately. Forskolin caused a small but significant increase in the permeability of the blood-aqueous barrier at the time of maximal intraocular pressure reduction. This effect on the blood-aqueous barrier may explain the inhibitory effect of forskolin on aqueous humor formation. PMID:3032517

Bartels, S P; Lee, S R; Neufeld, A H

1987-02-01

282

Involvement of cyclic AMP, iodide and metabolites of arachidonic acid in the regulation of cell proliferation of isolated porcine thyroid follicles.  

PubMed

Experiments with primary cultures of isolated porcine thyroid follicles were performed in serum-free well-defined medium to investigate different pathways that may be involved in the regulation of thyroid cell growth. The incorporation of [3H]thymidine into DNA within 72 h was about 25-fold with fetal calf serum (FCS, 1%), 20-fold with epidermal growth factor (EGF, 1 ng/ml) and 3.5-fold with insulin (10 micrograms/ml) as compared to controls. Bovine TSH significantly reduced the basal and insulin-induced growth rate at concentrations of 10(-6) to 10(-4) U/ml and 10(-4) U/ml, respectively. Forskolin stimulated cyclic AMP accumulation in thyroid cells and significantly reduced FCS-, EGF- or insulin-induced growth. In contrast, a 2- to 7-fold increase in FCS-, insulin- or EGF-induced growth rate was found, when cyclic AMP formation was inhibited by 2',5'-dideoxyadenosine (DDA). Iodide was stimulatory at low concentrations (1 microM) and inhibitory at higher concentrations (40-80 microM) on FCS-induced growth rate. The inhibitory effect of iodide was blocked by propylthiouracil (PTU), indicating that an iodinated compound is responsible for this effect. Indomethacin, a cyclooxygenase inhibitor, did not inhibit EGF- and insulin-induced growth up to a concentration of 100 microM. However, nordihydroguaiaretic acid (NDGA) and BW-755C, which are lipoxygenase inhibitors, strongly inhibited the growth of thyroid cells at micromolar concentrations. These data clearly show that (1) bovine TSH is not a growth factor for isolated thyroid cells in vitro, (2) thyroid cell proliferation, induced by FCS, EGF and insulin is under negative control of cyclic AMP. (3) Iodide controls dose-dependently thyroid cell growth by iodinated metabolites, probably modulating 2 different pathways: (a) at low iodide concentrations, an iodinated compound enhances the growth rate by inhibition of cyclic AMP formation, and (b) at high concentrations, iodide diminishes the growth rate by inhibiting the response to growth factors. (4) Metabolite(s) of lipoxygenase appear to be involved in intracellular signal transduction evoked by growth factors in thyroid cells. PMID:2998905

Gärtner, R; Greil, W; Demharter, R; Horn, K

1985-09-01

283

RAS/Cyclic AMP and Transcription Factor Msn2 Regulate Mating and Mating-Type Switching in the Yeast Kluyveromyces lactis ?  

PubMed Central

In response to harsh environmental conditions, ascomycetes produce stress-resistant spores to promote survival. As sporulation requires a diploid DNA content, species with a haploid lifestyle, such as Kluyveromyces lactis, first induce mating in response to stress. In K. lactis, mating and mating-type switching are induced by the DNA-binding protein Mts1. Mts1 expression is known to be upregulated by nutrient limitation, but the mechanism is unknown. We show that a ras2 mutation results in a hyperswitching phenotype. In contrast, strains lacking the phosphodiesterase Pde2 had lower switching rates compared to that of the wild type (WT). As Ras2 promotes cyclic AMP (cAMP) production and Pde2 degrades cAMP, these data suggest that low cAMP levels induce switching. Because the MTS1 regulatory region contains several Msn2 binding sites and Msn2 is a transcription factor that is activated by low cAMP levels, we investigated if Msn2 regulates MTS1 transcription. Consistently with this idea, an msn2 mutant strain displayed lower switching rates than the WT strain. The transcription of MTS1 is highly induced in the ras2 mutant strain. In contrast, an msn2 ras2 double mutant strain displays WT levels of the MTS1 transcript, showing that Msn2 is a critical inducer of MTS1 transcription. Strains lacking Msn2 and Pde2 also exhibit mating defects that can be complemented by the ectopic expression of Mts1. Finally, we show that MTS1 is subjected to negative autoregulation, presumably adding robustness to the mating and switching responses. We suggest a model in which Ras2/cAMP/Msn2 mediates the stress-induced mating and mating-type switching responses in K. lactis.

Barsoum, E.; Rajaei, N.; Astrom, S. U.

2011-01-01

284

The effects of alcohol on cyclic AMP in mouse brain  

Microsoft Academic Search

Detailed analysis of the dose-response and time-course relationship of ethanol to changes in adenosine 3',5'-cyclic monophosphate (cAMP) content of mouse brain revealed several patterns of response, including both decreases and increases depending on brain area. Whole-brain cAMP content was decreased with ethanol injection at all doses (0.4–3.2 g\\/kg), and reflected the decreased levels in the cortex. The subcortical and cerebellar

E. K. Orenberg; J. Renson; J. D. Barchas

1976-01-01

285

Cyclic AMP inhibits Cl-/HCO3- exchange at the apical membrane of Necturus gallbladder epithelium  

PubMed Central

Intracellular microelectrode techniques were employed to study the effect of cyclic AMP on apical membrane Cl-/HCO3- exchange and electrodiffusive HCO3- transport in Necturus gallbladder epithelium. Intracellular cAMP levels were raised by addition of either the phosphodiesterase inhibitor theophylline (3 X 10(-3) M) or the adenylate cyclase activator forskolin (10(-5) M) to the serosal bathing solution. Measurements of pH in a poorly buffered control mucosal solution upon stopping superfusion show acidification, owing to secretion of both H+ and HCO3-. When the same experiment is performed after addition of amiloride or removal of Na+ from the mucosal bathing medium, alkalinization is observed since H+ transport is either inhibited or reversed, whereas HCO3- secretion persists. The changes in pH in both amiloride or Na-free medium were significantly decreased in theophylline-treated tissues. Theophylline had no effect on the initial rates of fall of intracellular Cl- activity (aCli) upon reducing mucosal solution [Cl-] to either 10 or 0 mM, although membrane voltage and resistance measurements were consistent with stimulation of apical membrane electrodiffusive Cl- permeability. Estimates of the conductive flux, obtained by either reducing simultaneously mucosal [Cl-] and [HCO3-] or lowering [Cl-] alone in the presence of a blocker of anion exchange (diphenylamine-2-carboxylate), indicate that elevation of intracellular cAMP inhibited the anion exchanger by approximately 50%. Measurements of net Cl- uptake upon increasing mucosal Cl- from nominally zero to levels ranging from 2.5 to 100 mM suggest that the mechanism of inhibition is a decrease in Vmax. Consistent with these results, the rate of intracellular alkalinization upon reducing external Cl- was also inhibited significantly by theophylline. Reducing mucosal solution [HCO3-] from 10 to 1 mM under control conditions caused intracellular acidification and an increase in aCli. Theophylline inhibited both changes, by 62 and 32%, respectively. These data indicate that elevation of intracellular cAMP inhibits apical membrane anion (Cl-/HCO3-) exchange. Studies of the effects of rapid changes in mucosal [HCO3-] on membrane voltages and the apparent ratio of membrane resistances, both in the presence and in the absence of theophylline, with or without Cl- in the mucosal solution, do not support the hypothesis that cAMP produces a sizable increase in apical membrane electrodiffusive HCO3- permeability.

1987-01-01

286

A cyclic AMP and phorbol ester-inducible DNA element  

Microsoft Academic Search

Many cellular processes are regulated by hormones and neuro-transmitters which interact with cell-surface receptors to produce intracellular second messengers that activate protein kinases. Cyclic (c) AMP is a second messenger whose intracellular level is determined by receptor-mediated activation or inhibition of adeny-late cyclase1,2. Phorbol esters directly activate protein kinase C, a Ca2+ and phospholipid-dependent protein kinase3 and a component of

Michael Comb; Neal C. Birnberg; Audrey Seasholtz; Edward Herbert; Howard M. Goodman

1986-01-01

287

Dynamics of retinal waves are controlled by cyclic AMP.  

PubMed

Waves of spontaneous activity sweep across the developing mammalian retina and influence the pattern of central connections made by ganglion cell axons. These waves are driven by synaptic input from amacrine cells. We show that cholinergic synaptic transmission during waves is not blocked by TTX, indicating that release from starburst amacrine cells is independent of sodium action potentials. The spatiotemporal properties of the waves are regulated by endogenous release of adenosine, which sets intracellular cAMP levels through activation of A2 receptors present on developing amacrine and ganglion cells. Increasing cAMP levels increase the size, speed, and frequency of the waves. Conversely, inhibiting adenylate cyclase or PKA prevents wave activity. Together, these results imply a novel mechanism in which levels of cAMP within an immature retinal circuit regulate the precise spatial and temporal patterns of spontaneous neural activity. PMID:10595518

Stellwagen, D; Shatz, C J; Feller, M B

1999-11-01

288

Inhibition of calmodulin-dependent cyclic AMP phosphodiesterase by phenoxazines.  

PubMed

Phenoxazine derivatives were examined for their ability to inhibit the calmodulin-mediated activation of phosphodiesterase, which is based on the hydrolysis of cAMP to AMP by phosphodiesterase in the presence or absence of inhibitor, followed by quantitative analysis by HPLC method. Anticalmodulin activity of phenoxazines with respect to substitution at C-2 position follows the order: 2-trifluoromethyl>2-chloro>unsubstituted phenoxazines. The interaction of phenoxazines with calmodulin using fluorescence spectroscopy has been performed. Binding study showed that calmodulin has two types of binding sites for phenoxazines. One is high affinity binding site (Kd value 0.07-0.46 microM) and the other, a low affinity binding site (Kd value 0.7-34.5 microM). The change in secondary structure of calmodulin upon binding to phenoxazines was studied by circular dichroism (CD) method, which showed that the percentage of helicity decreased with an extensive change in tertiary structure of calmodulin. Kinetic analysis of the phenoxazine-calmodulin interaction showed that phenoxazines competitively inhibited the activation of phosphodiesterase without affecting Vmax. Thus, these studies showed a good correlation between the ability of phenoxazines to block the activation of phosphodiesterase and their ability to bind to the activator. PMID:16494842

Jagadeesh, Shankar; Padma, Thimmaiah; Parimala, Hanumesh; Chandramouli, K H; D'Souza, Cletus J M; Thimmaiah, Kuntebommanahalli N

2006-02-13

289

Cyclic AMP Effectors in African Trypanosomes Revealed by Genome-Scale RNA Interference Library Screening for Resistance to the Phosphodiesterase Inhibitor CpdA.  

PubMed

One of the most promising new targets for trypanocidal drugs to emerge in recent years is the cyclic AMP (cAMP) phosphodiesterase (PDE) activity encoded by TbrPDEB1 and TbrPDEB2. These genes were genetically confirmed as essential, and a high-affinity inhibitor, CpdA, displays potent antitrypanosomal activity. To identify effectors of the elevated cAMP levels resulting from CpdA action and, consequently, potential sites for adaptations giving resistance to PDE inhibitors, resistance to the drug was induced. Selection of mutagenized trypanosomes resulted in resistance to CpdA as well as cross-resistance to membrane-permeable cAMP analogues but not to currently used trypanocidal drugs. Resistance was not due to changes in cAMP levels or in PDEB genes. A second approach, a genome-wide RNA interference (RNAi) library screen, returned four genes giving resistance to CpdA upon knockdown. Validation by independent RNAi strategies confirmed resistance to CpdA and suggested a role for the identified cAMP Response Proteins (CARPs) in cAMP action. CARP1 is unique to kinetoplastid parasites and has predicted cyclic nucleotide binding-like domains, and RNAi repression resulted in >100-fold resistance. CARP2 and CARP4 are hypothetical conserved proteins associated with the eukaryotic flagellar proteome or with flagellar function, with an orthologue of CARP4 implicated in human disease. CARP3 is a hypothetical protein, unique to Trypanosoma. CARP1 to CARP4 likely represent components of a novel cAMP signaling pathway in the parasite. As cAMP metabolism is validated as a drug target in Trypanosoma brucei, cAMP effectors highly divergent from the mammalian host, such as CARP1, lend themselves to further pharmacological development. PMID:23877697

Gould, Matthew K; Bachmaier, Sabine; Ali, Juma A M; Alsford, Sam; Tagoe, Daniel N A; Munday, Jane C; Schnaufer, Achim C; Horn, David; Boshart, Michael; de Koning, Harry P

2013-07-22

290

Iontophoretic release of cyclic AMP and dispersion of melanosomes within a single melanophore  

PubMed Central

Selective dispersion of melanosomes was often observed after iontophoretic injection of cyclic adenosine monophosphate (AMP) from a glass microelectrode positioned in a target melanophore in frog skin (as viewed from above through a microscope), with other melanophores in the field serving as controls. Because the skin has orderly arrays of several types of closely spaced cells, it is probable that at times the microelectrode also impales cells other than melanophores. When cyclic AMP injection inside a cell resulted in dispersion of melanosomes from a perinuclear position into dendritic processes, the onset of dispersion was relatively rapid, in many cases less than 4 min (mean time of onset, 5.3 +/- 2.9 [SD] min). A much slower dispersion (mean time of onset, 19.0 +/- 5.0 min) of melanosomes was observed when the microelectrode was positioned adjacent to a melanophore, and much larger quantities of cyclic AMP were released. In addition, no changes were observed for injections of 5'-AMP or cyclic guanosine monophosphate (GMP) through electrodes positioned inside or adjacent to melanophores. Potential measurements showed that after impaling a clell, a constant transmembrane potential could often be recorded over many minutes, indicating that the membrane tends to seal around the microelectrode. The results indicate that cyclic AMP acts more rapidly on the inside of a cell than when applied outside a cell and allowed to diffuse through the plasma membrane. This study introduces a model system whereby the properties of the plasma membrane and melanocyte- stimulating hormone (MSH) receptors can be studies within a single target cell.

1977-01-01

291

GABAB receptors modulate catecholamine secretion in chromaffin cells by a mechanism involving cyclic AMP formation.  

PubMed Central

1. The function of gamma-aminobutyric acidB (GABAB) receptors in modulation of catecholamine secretion by chromaffin cells and the possible mechanism involved in this action have been examined. 2. The GABAB agonists (-)-baclofen and 3-aminopropylphosphinic acid (3-APPA) were found to induce a dose-dependent increase of basal catecholamine secretion. The EC50s were 151 +/- 35 microM and 225 +/- 58 microM for baclofen and 3-APPA, respectively. This stimulatory effect was specific since it could be blocked by 0.5 mM of the specific GABAB antagonist CGP-35348. 3. In contrast, preincubation of chromaffin cells with the GABAB agonists was found to inhibit, in a dose-dependent manner, the catecholamine secretion evoked by 10 microM nicotine and 200 microM muscimol. 4. The effects of GABAB agonists on both basal and evoked catecholamine secretion were found to be accompanied by parallel changes in intracellular calcium concentration ([Ca2+]i). GABAB agonists produced a dose-dependent increase in [Ca2+]i which was partially blocked by CGP 35348, but they produced a strong inhibition of the [Ca2+]i increase induced by nicotine and muscimol. 5. The GABAB agonists also produced a dose-dependent increase in intracellular cyclic AMP levels, there being a direct correlation between both increase in catecholamine secretion and in intracellular cyclic AMP levels. 6. The pretreatment of chromaffin cells with pertussis toxin doubled the catecholamine secretion and increased by four times the intracellular cyclic AMP levels evoked by GABAB agonists. 7. The possible involvement of adenylate cyclase in the mechanism of GABAA receptor modulation of catecholamine secretion is discussed.

Oset-Gasque, M. J.; ParramA?n, M.; GonzA?lez, M. P.

1993-01-01

292

Modulating action of cyclic AMP on the expression of two SOS genes in Escherichia coli K-12.  

PubMed

Ultraviolet irradiation and cyclic AMP treatment produce a synergistic effect on the induction of the cle1 gene (coding for bacteriocin ColE1) in wild-type strains of Escherichia coli. On the other hand, cyclic AMP does not affect the uv-mediated induction of the recA, sfiA, and umuDC genes. Growth in the presence of glucose or glycerol does not affect the factor of amplification of the expression of the cle1 gene in uv-irradiated cells of the wild-type strain. Although, in cultures not treated with uv, the basal level of cle1 induction is about twice as high in cell grown grown with glycerol as in those using glucose as carbon source. In recA mutants neither simultaneous nor separate treatments with either cyclic AMP or uv irradiation induced transcription of the cle1 gene. Moreover, cyclic AMP induced a slight increase in cle1 gene expression in uv-irradiated cya strains, but not in the crp mutants. Nevertheless, the pattern of the uv-mediated induction of other SOS genes, such as umuDC, was the same in the cya and crp mutants, as in their parental wild-type strains. Furthermore, the uv-mediated induction of lambda prophage was decreased after either addition of cyclic AMP or growth in cultural conditions where the level of this nucleotide was low. PMID:2825953

Barbé, J; Gibert, I; Guerrero, R

1987-08-01

293

Immunochemical visualization and quantitation of cyclic AMP in single cells.  

PubMed

Adenosine 3':5'-cyclic monophosphate (cAMP) is a key second messenger in signaling pathways governing many cellular processes. To define the subcellular localization and relative abundance of cAMP, we developed a novel immunochemical approach based on acrolein fixation to visualize cAMP within cells. We describe here the fixation and immobilization of cAMP within cells and the production of specific, high titer polyclonal antibodies that recognize cAMP. Relative levels of cAMP immunofluorescence were quantitated in glial cells (oligodendrocytes, astrocytes, Schwann cells, and glioma cells) that were either untreated or treated with activators of endogenous adenylyl cyclase to raise cAMP levels. In treated cells, cAMP immunofluorescence is strongly localized in the perinuclear cytoplasm. PMID:9395484

Wiemelt, A P; Engleka, M J; Skorupa, A F; McMorris, F A

1997-12-12

294

Effect of cyclic GMP-dependent vasodilators on the expression of inducible nitric oxide synthase in vascular smooth muscle cells: role of cyclic AMP.  

PubMed

1. In the present study we examined whether interleukin-1 beta (IL-1 beta) increases the activity of adenylyl cyclase in vascular smooth muscle cells and determined its role in the cytokine-induced expression of the inducible nitric oxide synthase (iNOS) and activation of nuclear transcription factor-kappa B (NF-kappa B). In addition the interaction between cyclic AMP- and cyclic GMP-elevating agonists on the IL-1 beta-stimulated expression of iNOS was examined. 2. Exposure of vascular smooth muscle cells to IL-1 beta stimulated the formation of cyclic AMP but not of cyclic GMP. The intracellular level of cyclic AMP reached a maximum within 1 h and then gradually declined over the next 5 h. This IL-1 beta (60 u ml-1)-stimulated formation of cyclic AMP was modest (about 3 fold at 60 u ml-1 for 1 h) compared to that evoked by isoprenaline (about 9 fold at 3 x 10(-6) M for 2 min). 3. The IL-1 beta (60 u ml-1 for 24 h)-stimulated accumulation of nitrite, which was taken as an index of NO production, was concentration-dependently increased by preferential inhibitors of cyclic AMP-dependent phosphodiesterases (rolipram and trequinsin). This effect was reproduced by a specific activator of the cyclic AMP-dependent protein kinase(s) A, Sp-8-CPT-cAMPS (10(-4) M) but was prevented by a specific inhibitor of cyclic AMP-dependent protein kinase(s) A, Rp-8-CPT-cAMPS (10(-4) M). These compounds alone [rolipram (10(-6) M), trequinsin (3 x 10(-6) M) and Sp-8-CPT-cAMPS (10(-4) M)] slightly but significantly increased the release of nitric oxide while Rp-8-CPT-cAMPS elicited no such effect. 4. Inducible NOS protein was expressed in IL-1 beta (30 u ml-1, 24 h)-stimulated smooth muscle cells as assessed by Western blot analysis. The level of iNOS protein was markedly increased in smooth muscle cells which had been exposed to IL-1 beta in combination with either rolipram (3 x 10(-6) M) or Sp-8-CPT-cAMPS (10(-4) M) but was reduced in those exposed to IL-1 beta and Rp-8-CPT-cAMPS (10(-4) M). A weak expression of iNOS protein was found in smooth muscle cells which had been exposed to either Sp-8-CPT-cAMPS or rolipram alone for 24 h while Rp-8-CPT-cAMPS elicited no such effect. 5. Exposure of smooth muscle cells to IL-1 beta (30 u ml-1) for 30 min increased the level of NF-kappa B-DNA complexes in nuclear extracts as detected by electrophoretic mobility shift assay. Similar levels of NF-kappa B-DNA complexes were found in cells which had been exposed to IL-1 beta in combination with either Sp-8-CPT-cAMPS (10(-4) M), trequinsin (10(-6) M) or rolipram (10(-6) M). None of the modulators alone affected the basal level of NF-kappa B binding activity. 6. NO-donors [sodium nitroprusside (SNP) 10(-4) M; dinitrosyl-iron-di-L-cysteine-complex (DNIC), 10(-4) M; 3-morpholino-sydnonimine (SIN-1), 10(-4) M] and atrial natriuretic factor (10(-6) M) significantly increased the IL-1 beta (30 or 60 u ml-1, 24 h)-stimulated expression of iNOS protein and activity as assessed indirectly by the conversion of oxyhaemoglobin to methaemoglobin. In the absence of IL-1 beta, SNP (10(-4) M, 24 h) but not the other cyclic GMP-dependent vasodilators caused a modest expression of iNOS protein. No such effect was found in smooth muscle cells exposed to SNP in combination with Rp-8-CPT-cAMPS (10(-4) M) while an increased level of iNOS protein was found in those exposed to SNP in combination with either Sp-8-CPT-cAMPS (10(-4) M) or rolipram (3 x 10(-6) M). 7. Exposure of vascular smooth muscle cells to either S-nitroso-L-cysteine (Cys-SNO, 10(-4) M), SNP (10(-4) M) or SIN-1 (10(-4) M) for 35 min affected minimally the basal activation of NF-kappa B but abolished that evoked by IL-1 beta (30 u ml-1 added during the last 30 min). However, addition of Cys-SNO following the stimulation with IL-1 beta (during the last 5 min of the 30 min exposure period) reduced the level of NF-kappa B-DNA complexes only slightly. 8. These data indicate that the cyclic AMP-dependent pathway plays a decisi PMID:8904645

Boese, M; Busse, R; Mülsch, A; Schini-Kerth, V

1996-10-01

295

Effect of cyclic AMP on barrier function of human lymphatic microvascular tubes  

Microsoft Academic Search

This work examines the effect of cyclic AMP (cAMP) on the in vitro barrier function of tubes of human dermal lymphatic microvascular endothelial cells (LECs). Under baseline conditions, the barrier function of LEC tubes was weak, with diffusional permeability coefficients to bovine serum albumin and 10 kDa dextran of 1.4?0.6+0.9×10?6 cm\\/s and 1.7?0.5+0.8×10?6 cm\\/s (geometric mean±95% CI), respectively, and 1.2±0.5 (mean±95% CI) focal

Gavrielle M. Price; Kenneth M. Chrobak; Joe Tien

2008-01-01

296

The myriad roles of cyclic AMP in microbial pathogens, from signal to sword  

PubMed Central

All organisms must sense and respond to their external environments, and this signal transduction is often done with second messengers such as cyclic nucleotides. Adenosine 3'5'-cyclic AMP is a universal second messenger that is used by diverse forms of life, including mammals, fungi, protozoa and bacteria. In this review, we discuss the many roles of cAMP in bacterial, fungal and protozoan pathogens and its contributions to microbial pathogenesis. These include coordination of intracellular processes such as virulence gene expression with extracellular signals from the host environment, and manipulation of host immunity by increasing cAMP levels in host cells during infection.

McDonough, Kathleen A.; Rodriguez, Ana

2013-01-01

297

Energetics of cyclic AMP binding to HCN channel C terminus reveal negative cooperativity.  

PubMed

Cyclic AMP binds to the HCN channel C terminus and variably stabilizes its open state. Using isothermal titration calorimetry, we show that cAMP binds to one subunit of tetrameric HCN2 and HCN4 C termini with high affinity (?0.12 ?M) and subsequently with low affinity (?1 ?M) to the remaining three subunits. Changes induced by high affinity binding already exist in both a constrained HCN2 tetramer and the unconstrained HCN1 tetramer. Natural "preactivation" of HCN1 may explain both the smaller effect of cAMP on stabilizing its open state and the opening of unliganded HCN1, which occurs as though already disinhibited. PMID:22084239

Chow, Sarah S; Van Petegem, Filip; Accili, Eric A

2011-11-14

298

Effect of cerebral injury on cerebrospinal fluid cyclic AMP concentration.  

PubMed

Cerbrospinal fluid (CSF) cyclic adenosine-3', 5'-monophosphate (cAMP) was measured in rabbits after experimental brain injury as well as in patients with cerebral contusion and cerebral concussion. In rabbits a marked elevation lasting for two weeks was observed. From the third week onwards after the injury the CSF cAMP concentration was lower than the basal level before the injury. Dexamethasone partly inhibited the elevation. Ethanol treatment decreased the CSF cAMP values. In man, the CSF cAMP concentration was significantly higher in patients with cerebral contusion than in those with cerebral concussion. Also in the latter group the cAMP values were higher than in control patients. Due to the clear differences between the various groups, measurement of cAMP concentration in CSF might have diagnostic value in evaluation of the severity of cerebral lesion in the acute phase. Also the activities of some enzymes were measured, and the results were parallel with cAMP changes but less striking. PMID:186266

Myllyla, V V

1976-01-01

299

Histamine augments beta2-adrenoceptor-induced cyclic AMP accumulation in human prostate cancer cells DU-145 independently of known histamine receptors.  

PubMed

Androgen-independent prostate cancer cells DU-145 express a number of G protein-coupled receptors, including histamine H1 receptors. There is evidence for the presence of beta-adrenoceptors in the human prostate, and in this work we set out to characterise the expression of beta-adrenoceptors by DU-145 cells, their linking to cyclic AMP (cAMP) formation and the possible modulation by histamine H1 receptors of beta-adrenoceptor function. Saturation [3H]-dihydroalprenolol binding indicated that DU-145 cells express moderate levels of beta-adrenoceptors (22.7+/-2.5 fmol/mg protein), which belong to the beta2-subtype as assessed by inhibition by the antagonists ICI-118,551 and CGP-20712A. Inhibition of [3H]-dihydroalprenolol binding by agonists (noradrenaline, adrenaline and isoproterenol) showed the presence of both high-(53-59%) and low-affinity binding sites. beta-Adrenoceptor stimulation with isoproterenol resulted in robust [3H]-cAMP accumulation (10-30-fold of basal, EC50 142 nM; pEC50 6.85+/-0.05). While not having effect of its own on basal [3H]-cAMP accumulation, histamine significantly augmented the beta2-adrenoceptor-induced response (overall effect 152+/-6% of isoproterenol alone) with EC50 1.35 microM (pEC50 5.87+/-0.06). This effect was independent of extracellular Ca2+, insensitive to antagonists/agonists at H1, H2 or H3/H4 receptors and mimicked by drugs containing an imidazole ring in their chemical structure and by imidazole itself. Taken together, our results show that in DU-145 cells histamine augments beta2-adrenoceptor-induced cAMP independently of the activation of known histamine receptors. The effect may involve other mechanisms such as allosteric modulation of beta2-adrenoceptors by the imidazole moiety of histamine. PMID:17196553

Ramos-Jiménez, Judith; Soria-Jasso, Luis-Enrique; López-Colombo, Aurelio; Reyes-Esparza, Jorge-Alberto; Camacho, Javier; Arias-Montaño, José-Antonio

2006-12-01

300

Involvement of cyclic AMP receptor protein in regulation of the rmf gene encoding the ribosome modulation factor in Escherichia coli.  

PubMed

The decrease in overall translation in stationary-phase Escherichia coli is accompanied with the formation of functionally inactive 100S ribosomes mediated by the ribosome modulation factor (RMF). At present, however, little is known regarding the regulation of stationary-phase-coupled RMF expression. In the course of a systematic screening of regulation targets of DNA-binding transcription factors from E. coli, we realized that CRP (cyclic AMP [cAMP] receptor protein), the global regulator for carbon source utilization, participates in regulation of some ribosomal protein genes, including the rmf gene. In this study, we carried out detailed analysis of the regulation of the RMF gene by cAMP-CRP. The cAMP-dependent binding of CRP to the rmf gene promoter was confirmed by gel shift and DNase I footprinting assays. By using a reporter assay system, the expression level of RMF was found to decrease in the crp knockout mutant, indicating the involvement of CRP as an activator of the rmf promoter. In good agreement with the reduction of rmf promoter activity, we observed decreases in RMF production and 100S ribosome dimerization in the absence of CRP. Taken together, we propose that CRP regulates transcription activation of the rmf gene for formation of 100S ribosome dimers. Physiological roles of CRP involvement in RMF production are discussed. PMID:23475967

Shimada, Tomohiro; Yoshida, Hideji; Ishihama, Akira

2013-03-08

301

Effects of granulocyte-macrophage colony-stimulating factor and cyclic AMP interaction on human neutrophil apoptosis.  

PubMed Central

The current study was undertaken to evaluate the effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) and cyclic AMP (cAMP) signaling interaction on human neutrophil apoptosis, either occurring spontaneously or induced by Fas antigen activation. Results show that GM-CSF, dibutyryl cAMP (a cAMP analog) and forskolin (an adenylate cyclase activator) are all able to suppress spontaneous neutrophil cell death. Of note however, when GM-CSF is used in combination with cAMP-elevating agents, an additive effect on neutrophil survival is observed with dibutyryl cAMP only, whereas supplementation of cell cultures with GM-CSF and forskolin results in a progressive reduction of antiapoptotic effects exerted by the single compounds. Moreover, although dibutyryl cAMP and forskolin do not affect Fas-triggered apoptotic events, they are still able to modulate the GM-CSF capacity to prolong neutrophil survival following anti-Fas IgM cell challenge, with effects similar to those respectively exerted on spontaneous neutrophil apoptosis. The data indicate that GM-CSF may negatively modulate the cAMP-mediated antiapoptotic pathway in human neutrophils, likely via the inhibition of adenylate cyclase activity. This would prevent an abnormal neutrophil survival as a result of cAMP signaling stimulation, which provides a novel insight into the role of GM-CSF as a physiological regulator of myeloid cell turnover.

Tortorella, C; Piazzolla, G; Spaccavento, F; Antonaci, S

1998-01-01

302

Characterization of Mycobacterium tuberculosis Rv3676 (CRPMt), a cyclic AMP receptor protein-like DNA binding protein.  

PubMed

Little is known about cyclic AMP (cAMP) function in Mycobacterium tuberculosis, despite its ability to encode 15 adenylate cyclases and 10 cNMP-binding proteins. M. tuberculosis Rv3676, which we have designated CRP(Mt), is predicted to be a cAMP-dependent transcription factor. In this study, we characterized CRP(Mt)'s interactions with DNA and cAMP, using experimental and computational approaches. We used Gibbs sampling to define a CRP(Mt) DNA motif that resembles the cAMP receptor protein (CRP) binding motif model for Escherichia coli. CRP(Mt) binding sites were identified in a total of 73 promoter regions regulating 114 genes in the M. tuberculosis genome, which are being explored as a regulon. Specific CRP(Mt) binding caused DNA bending, and the substitution of highly conserved nucleotides in the binding site resulted in a complete loss of binding to CRP(Mt). cAMP enhanced CRP(Mt)'s ability to bind DNA and caused allosteric alterations in CRP(Mt) conformation. These results provide the first direct evidence for cAMP binding to a transcription factor in M. tuberculosis, suggesting a role for cAMP signal transduction in M. tuberculosis and implicating CRP(Mt) as a cAMP-responsive global regulator. PMID:16267303

Bai, Guangchun; McCue, Lee Ann; McDonough, Kathleen A

2005-11-01

303

Elevation of cyclic AMP levels in HL-60 cells accumulated in G1 or G2 by transmethylation inhibitors.  

PubMed

Effects of the transmethylation inhibitors 3-deazaadenosine (c3Ado) and 3-deaza-(+/-)-aristeromycin (c3Ari) on cell cycle and cyclic AMP (cAMP) concentrations in human promyelocytic leukemia cells (HL-60) were studied by flow cytometry and radioimmunoassay techniques. Previously described cell cycle accumulations, after incubation with drugs (25 microM) for two cell doublings (36 hr), were localized to G1 and G2 after incubation with c3Ado and c3Ari, respectively. cAMP levels were elevated in cells treated with c3Ado (35%) and c3Ari (92%) for 36 hr. Addition of the phosphodiesterase (PDE) inhibitor theophylline, increased cAMP levels further, while cAMP responsiveness to the beta-adrenergic stimulator isoproterenol was attenuated after c3Ado and c3Ari incubation. Homocysteine thiolactone (Hcy) alone reduced cell growth slightly (5%) and increased cAMP levels (17%). Hcy increased the growth inhibitory effects of c3Ado, while no modulating effect was seen in combination with c3Ari, nor did Hcy counteract the effects on the cell cycle perturbations. The results suggest that c3Ado- and c3Ari-induced cell cycle accumulation is, at least in part, mediated through cAMP elevation, possibly due to PDE inhibition secondary to S-adenosyl-homocysteine hydrolase inhibition and S-adenosyl-homocysteine build-up. PMID:1656997

Prytz, P S; Bang, B E; Endresen, P C; Møller, C; Aarbakke, J

1991-10-01

304

Cyclic AMP-elevating agents prolong or inhibit eosinophil survival depending on prior exposure to GM-CSF.  

PubMed Central

1. Purified human eosinophils survived for up to 7 days when cultured in vitro in the presence of 1 ng ml-1 granulocyte-macrophage colony stimulating factor (GM-CSF) with a viability of 73%. In the absence of GM-CSF, eosinophil viability decreased after one day in culture, and only 4% of cells were viable by day 4. 2. Culture of eosinophils with cholera toxin produced a concentration-dependent decrease in GM-CSF-induced survival at 7 days (IC50 = 7 ng ml-1) which was associated with a 6 fold increase in the intracellular cyclic AMP concentration. This inhibition of cell survival could be prevented by the addition of the protein kinase A inhibitor, H89 (10(-6)M). 3. When eosinophils were cultured with dibutyryl cyclic AMP, there was a concentration-dependent inhibition of GM-CSF-induced survival at 7 days with an IC50 of 200 microM. The related cyclic nucleotide analogue, dibutyryl cyclic GMP did not inhibit GM-CSF-induced eosinophil survival over the same concentration range. 4. Culture of eosinophils with forskolin, or with the phosphodiesterase inhibitors, rolipram and SK&F94120, had no effect on GM-CSF-induced eosinophil survival at any concentration examined. 5. After 7 days' culture in the absence of GM-CSF, fractionation of eosinophil DNA on agarose gels demonstrated a 'ladder' pattern characteristic of apoptosis. GM-CSF prevented DNA fragmentation and this protection could be overcome by both cholera toxin and dibutyryl cyclic AMP. 6. GM-CSF did not affect intracellular cyclic AMP concentrations in unstimulated eosinophils or in cells stimulated by cholera toxin. Thus, GM-CSF does not apparently increase eosinophil survival by affecting cyclic AMP levels. 7. In the absence of GM-CSF both cholera toxin and dibutyryl cyclic AMP decreased the rate of eosinophil death, when compared to cells cultured with medium alone. The t1/2 values for cell death were 1.63 +/- 0.3, 2.46 +/- 0.3 and 4.62 +/- 1.0 days for cells cultured in the presence of medium, cholera toxin and dibutyryl cyclic AMP respectively. 8. In conclusion, cyclic AMP exerts opposing effects on eosinophil survival depending on prior exposure of the cells to GM-CSF. Images Figure 5

Hallsworth, M. P.; Giembycz, M. A.; Barnes, P. J.; Lee, T. H.

1996-01-01

305

The endogenous cyclic AMP antagonist, cyclic PIP: its ubiquity, hormone-stimulated synthesis and identification as prostaglandylinositol cyclic phosphate.  

PubMed

This report shows that the cyclic AMP antagonist cyclic PIP is present in all organs and tissues of the rat so far examined: brain, heart, lung, intestine, kidney, liver, spleen, skeletal muscle and fat. The synthesis of cyclic PIP is stimulated by insulin or noradrenaline (alpha-adrenergic action) in a dose-dependent fashion. Increasing cyclic PIP synthesis with increasing insulin concentrations matches the insulin receptor binding curves. Cyclic PIP levels in blood serum remain low after hormonal stimulation and no cyclic PIP can be detected in urine. As an indication of its ubiquity, cyclic PIP was even detected in yeast. Prostaglandin E (as shown by incorporation of [3H]PGE into cyclic PIP and demonstration of a constant specific activity), myo-inositol (as shown by acid hydrolysis of the dephosphorylated cyclic PIP and mass spectrometric identification of the products) and one phosphate (as shown by the ionic nature of cyclic PIP and its inactivation by phosphodiesterase plus phosphatase) are components of cyclic PIP. Chemical derivatization experiments of cyclic PIP suggest the phosphate to be bound to myo-inositol and the myo-inositol phosphate to the prostaglandin E by its C15-hydroxyl group. PMID:8180414

Wasner, H K; Salge, U; Gebel, M

1993-01-01

306

Regulation of endogenous Ca2+ channels by cyclic AMP and cyclic GMP-dependent protein kinases in Pleurodeles oocytes.  

PubMed

The effects of cyclic AMP (cAMP) and cyclic GMP (cGMP) on dihydropyridine sensitive Ca2+ channels were investigated under voltage-clamp in defolliculated Pleurodeles oocytes. Intracellular injection of cAMP or extracellular application of the permeable cAMP analogue (8-Bromo cAMP, 8Br-cAMP) decreased the Ba current (IBa). This effect on IBa was blocked by the injection of protein kinase A inhibitor. Similar results were found upon internal application of the catalytic subunit of protein kinase A. In contrast, the injection of cGMP or perfusion of 8Br-cGMP increased IBa amplitude. The increase of IBa by 8Br-cGMP was blocked by the injection of the selective inhibitor of protein kinase G (KT5823). These results support the hypothesis that the basal Ba current amplitude of Pleurodeles oocytes is under the control of Protein Kinases A (PKA) and G (PKG) activity. This regulation of Ca2+ channels by the second messengers, and particularly by cAMP may reflect an important step in the maturation processus of Pleurodeles oocytes. PMID:9062905

Van Coppenolle, F; Ahidouch, A; Guilbault, P; Ouadid, H

1997-03-01

307

N-acetylneuraminic acid (NANA) stimulates in situ cyclic AMP production in tentacles of sea anemone (Aiptasia pallida): possible role in chemosensitization of nematocyst discharge.  

PubMed

Cnidocytes, the stinging cells of cnidarians, optimally discharge nematocysts in response to combined physical contact and stimulation of specific chemoreceptors. In the tentacles of certain sea anemones, the primary chemoreceptors bind N-acetylated sugars, such as N-acetylneuraminic acid (NANA). Sensitization with NANA predisposes contact-sensitive mechanoreceptors (CSMs) to trigger discharge in response to physical contact. In the ectoderm of sea anemone tentacles, cnidocyte/supporting cell complexes (CSCCs) control and trigger nematocyst discharge. Previous findings have implicated cyclic AMP (cAMP) as a second messenger in NANA-sensitized nematocyst discharge. However, no reports have directly demonstrated that the cAMP content of tentacles changes in response to NANA stimulation. We now show that NANA elevates in situ cAMP levels in a dose-dependent manner in the ectoderm of tentacles from the sea anemone Aiptasia pallida. However, the endoderm of tentacles shows no detectable cAMP response to NANA. The effect of NANA on the cAMP content of the ectoderm is biphasic. Micromolar NANA increases the in situ cAMP level, with a maximal response occurring at 1.8x10(-5)mol x l(-1) NANA. At higher NANA concentrations, the cAMP content decreases to that of controls. Because the cAMP dose/response curve to NANA coincides precisely with the dose/response curves of NANA-sensitized nematocyst discharge and nematocyst-mediated adhesive force, a second-messenger role for cAMP in NANA-sensitized nematocyst discharge is strongly suggested. The addition of isobutyl-1-methylxanthine (IBMX) to the medium with sea anemones increases tissue cAMP levels both in the absence and in the presence of NANA. However, anesthetizing anemones in sea water containing high levels of Mg(2+) blocks the NANA-stimulated cAMP response of the ectoderm. In addition, our results suggest that NANA-stimulated cAMP may activate endogenous cAMP-dependent protein kinase (PKA) in broken cell preparations of tentacles. Thus, NANA-stimulated cAMP may function as a second messenger in the NANA chemosensory signaling pathway controlling nematocyst discharge. PMID:11441042

Ozacmak, V H; Thorington, G U; Fletcher, W H; Hessinger, D A

2001-06-01

308

Mechanism of action of hydrogen sulfide on cyclic AMP formation in rat retinal pigment epithelial cells.  

PubMed

Hydrogen sulfide (H(2)S), a colorless gas with the pungent odor of rotten eggs has been reported to produce pharmacological actions in ocular and non-ocular tissues. We have evidence that H(2)S, using sodium hydrosulfide (NaHS) and sodium sulfide (Na(2)S) as donors can increase cyclic AMP (cAMP) production in neural retina. In the present study, we investigated the mechanism of action of H(2)S on cyclic nucleotide production in rat retinal pigment epithelial cells (RPE-J). Cultured RPE-J cells were incubated for 30 min in culture medium containing the cyclic nucleotide phosphodiesterase (PDE) inhibitor, IBMX (2 mM). Cells were exposed to varying concentrations of NaHS, the H(2)S substrate (L-cysteine), cyclooxygenase (COX) inhibitors or the diterpene activator of adenylate cyclase, forskolin in the presence or absence of H(2)S biosynthetic enzymes or the ATP-sensitive potassium (K(ATP)) channel antagonist, glibenclamide. Following drug-treatment at different time intervals, cell homogenates were prepared for cAMP assay using a well established methodology. In RPE-J cells, NaHS (10 nM-1 ?M) produced a time-dependent increase in cAMP concentrations over basal levels which reached a maximum at 20 min. At this time point, both NaHS (1 nM-100 ?M) and L-cysteine (1 nM-10 ?M) produced a concentration-dependent significant (p<0.05) increase in cAMP concentrations over basal level. The effects of NaHS on cAMP levels in RPE-J cells was enhanced significantly (p<0.01) in the presence of the COX inhibitors, indomethacin and flurbiprofen. In RPE-J cells, the effects caused by forskolin (10 ?M) on cAMP production were potentiated by addition of low concentrations of NaHS. Both the inhibitor of cystathionine ?-synthase (CBS), aminooxyacetic acid (AOA, 1 mM) and the inhibitor of cystathionine ?-lyase (CSE), proparglyglycine (PAG, 1mM) significantly attenuated the increased effect of L-cysteine on cAMP production. The K(ATP) channel antagonist, glibenclamide (100 ?M) caused inhibition of NaHS induced-increase of cAMP formation in RPE-J cells. We conclude that, H(2)S (using H(2)S donor and substrate) can increase cAMP production in RPE-J cells, and removal of the apparent inhibitory effect of prostaglandins unmasks an excitatory activity of H(2)S on cAMP. Effects elicited by the H(2)S substrate on cAMP formation are dependent on biosynthesis of H(2)S catalyzed by the biosynthetic enzymes, CBS and CSE. In addition to the adenylyl cylcase pathway, K(ATP) channels are involved in mediating the observed effects of the H(2)S on cAMP production. PMID:22445555

Njie-Mbye, Ya Fatou; Kulkarni, Madhura; Opere, Catherine A; Ohia, Sunny E

2012-03-14

309

Activating transcription factor 4  

Microsoft Academic Search

Activating transcription factor 4 (ATF4) belongs to the ATF\\/CREB (activating transcription factor\\/cyclic AMP response element binding protein) family of basic region-leucine zipper (bZip) transcription factors, which have the consensus binding site cAMP responsive element (CRE). ATF4 has numerous dimerization partners. ATF4 is induced by stress signals including anoxia\\/hypoxia, endoplasmic reticulum stress, amino acid deprivation, and oxidative stress. ATF4 expression is

Kurosh Ameri; Adrian L. Harris

2008-01-01

310

Neutrophil beta-adrenergic receptor responses are potentiated by acute exposure to phorbol ester without changes in receptor distribution or coupling  

SciTech Connect

Exposure to the phorbol ester, phorbol 12-myristate, 13-acetate for 10 minutes enhanced cyclic AMP accumulation in human neutrophils under basal conditions and in response to the beta-adrenergic receptor agonist isoproterenol (ISO, 1{mu}M) and the adenylate cyclase activator forskolin (FSK, 10mM). Potentiation of responses to ISO by PMA was dose-dependent between 0.1 and 100nM PMA. The diacylglycerol analogue, 1-oleoyl-2-actylgylcerol (OAG) (50 {mu}M) also elevated beta-receptor responses, but 4beta-phorbol (100nM), lacking the capacity to activate PMA, was ineffective. Short-term exposure to the peptide n-formylmethionine leucyl-phenylalanine (FMLP, 1 {mu}M) also elevated neutrophil cyclic AMP accumulation. All potentiating effects of PMA on cyclic AMP production were inhibited by the protein kinase inhibitor 1-(5-isoquinolinylsulphonyl)-2-methylpiperazine (H{sub 7}). PMA had no apparent effect on beta-receptor agonist-affinity, distribution between cell-surface and internalized compartments, or the capacity of ISO to induce beta-receptor internalization. Responses to FSK or ISO in terms of fold-stimulation of basal cyclic AMP accumulation int he presence of PMA were not elevated by PMA.

Kilfeather, S.A.; Stein, M.; O'Malley, K. (Royal College of Surgeons, Dublin (Ireland))

1991-01-01

311

Cyclic AMP increases cell surface expression of functional Na,K-ATPase units in mammalian cortical collecting duct principal cells.  

PubMed

Cyclic AMP (cAMP) stimulates the transport of Na(+) and Na,K-ATPase activity in the renal cortical collecting duct (CCD). The aim of this study was to investigate the mechanism whereby cAMP stimulates the Na,K-ATPase activity in microdissected rat CCDs and cultured mouse mpkCCD(c14) collecting duct cells. db-cAMP (10(-3) M) stimulated by 2-fold the activity of Na,K-ATPase from rat CCDs as well as the ouabain-sensitive component of (86)Rb(+) uptake by rat CCDs (1.7-fold) and cultured mouse CCD cells (1.5-fold). Pretreatment of rat CCDs with saponin increased the total Na,K-ATPase activity without further stimulation by db-cAMP. Western blotting performed after a biotinylation procedure revealed that db-cAMP increased the amount of Na,K-ATPase at the cell surface in both intact rat CCDs (1.7-fold) and cultured cells (1.3-fold), and that this increase was not related to changes in Na,K-ATPase internalization. Brefeldin A and low temperature (20 degrees C) prevented both the db-cAMP-dependent increase in cell surface expression and activity of Na,K-ATPase in both intact rat CCDs and cultured cells. Pretreatment with the intracellular Ca(2+) chelator bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid also blunted the increment in cell surface expression and activity of Na,K-ATPase caused by db-cAMP. In conclusion, these results strongly suggest that the cAMP-dependent stimulation of Na,K-ATPase activity in CCD results from the translocation of active pump units from an intracellular compartment to the plasma membrane. PMID:11179413

Gonin, S; Deschênes, G; Roger, F; Bens, M; Martin, P Y; Carpentier, J L; Vandewalle, A; Doucet, A; Féraille, E

2001-02-01

312

Identification of Cyclic AMP-Regulated Genes in Mycobacterium tuberculosis Complex Bacteria under Low-Oxygen Conditions  

Microsoft Academic Search

Mycobacterium tuberculosis is the etiological agent of tuberculosis (TB), which kills approximately 2 million people a year despite current treatment options. A greater understanding of the biology of this bacterium is needed to better combat TB disease. The M. tuberculosis genome encodes as many as 15 adenylate cyclases, suggesting that cyclic AMP (cAMP) has an important, yet overlooked, role in

Michaela A. Gazdik; Kathleen A. McDonough

2005-01-01

313

Influence of cell type on the steroidogenic potential and basal cyclic AMP levels of ras-oncogene-transformed rat cells  

Microsoft Academic Search

Transformation with ras oncogenes causes loss, maintenance or modulation of differentiation, depending on the developmental history of the target cells. In the present study, we examined steps in signal transduction that may underlie some of this variation, using steroidogenic cells of adult rats as the model system. Steroidogenesis in normal cells is regulated by cyclic AMP and protein kinase A

Jie Pan; Calvin D. Roskelley; Nelly Auersperg

1995-01-01

314

Synergistic Inhibition of Growth of Breast and Colon Human Cancer Cell Lines by Site-selective Cyclic AMP Analogues  

Microsoft Academic Search

Our past studies on the mechanism of cyclic AMP (cAMP)-mediated control of tumor growth, using the experimental rat mammary tumor models as well as human breast cancer cell lines, indicated that the action of cAMP is mediated by the R\\

Pierosandro Tagliaferri; Dionyssios Katsaros; Timothy Clair; Giampaolo Tortora; Leonard Neckers; Yu-an Chang; Ganapathi R. Revankar; Gerald W. Crabtree; Roland K. Robins; Yoon Sang

1988-01-01

315

Enhancement of gap junctional intercellular communication by dibutyryl cyclic AMP in lung epithelial cells.  

PubMed

Reduced gap junctional intercellular communication (GJIC) occurs in neoplastic cells and contributes to their phenotype. Cyclic AMP agonists inhibit lung cancer cell growth and enhance GIIC in other cell types, but little is known about their effects on lung epithelial cell gap junctions. We have examined whether N6, 2'-O-dibutyryladenosine 3':5'-cyclic mono-phosphate (DBcAMP) affected GJIC, gap junction protein (connexin43) expression, and the growth of non-transformed and neoplastic mouse lung epithelial cells. DBcAMP (0.01.1 mM) stimulated GJIC (assayed by fluorescent dye microinjection) and connexin43 expression (assessed by Northern and Western blotting) and reduced their proliferation. These results suggest an association between cAMP growth inhibition and enhanced GJIC in lung epithelial cells. PMID:9042246

Banoub, R W; Fernstrom, M; Malkinson, A M; Ruch, R J

316

Primary culture of human aortic intima cells as a model for testing antiatherosclerotic drugs. Effects of cyclic AMP, prostaglandins, calcium antagonists, antioxidants, and lipid-lowering agents.  

PubMed

Smooth muscle cells isolated from atherosclerotic lesions of human aorta retain in primary culture their intrinsic in vivo characteristics: namely, enhanced proliferative activity and high lipid levels. We have tested the effect of different compounds on [3H]thymidine uptake and on the levels of phospholipids, triglycerides, cholesterol, and cholesteryl esters in cultured aortic cells. Effects, such as the inhibition of cellular proliferation and/or lowering of the intracellular lipid levels which would be regarded as antiatherosclerotic if exerted in vivo, were observed in vitro by the following compounds: dibutyryl cyclic AMP, cholera toxin, forskolin, methylisobutylxanthine, stable prostacyclin analogues, prostaglandins E2 and D2, verapamil, reserpine, alpha-tocopherol, butylated hydroxytoluene, lipostabil, and high density lipoproteins. In this paper, we discuss the possibility of using a primary culture of smooth muscle cells from an atherosclerotic human aorta for testing drugs for possible antiatherosclerotic activity. PMID:3013216

Orekhov, A N; Tertov, V V; Kudryashov, S A; Khashimov, Kh A; Smirnov, V N

1986-05-01

317

Ethanol increases receptor-dependent cyclic AMP production in cultured hepatocytes by decreasing G(i)-mediated inhibition.  

PubMed Central

Increasing evidence suggests that ethanol-induced changes in cyclic AMP (cAMP) signal transduction play a critical role in the acute and chronic effects of ethanol. Here we have investigated the effects of ethanol on cAMP signal transduction in primary cultures of rat hepatocytes. Acute exposure to ethanol had a biphasic effect on glucagon-receptor-dependent cAMP production in intact cells: 25-50 mM-ethanol decreased cAMP, whereas treatment with 100-200 mM-ethanol increased cAMP. After chronic exposure to 50-200 mM-ethanol for 48 h in culture, glucagon-receptor-dependent cAMP levels were increased, but no change in glucagon receptor number was observed. These effects of ethanol were independent of ethanol oxidation. Chronic ethanol treatment also increased adenosine-receptor- and forskolin-stimulated cAMP production. Increased cAMP production was also observed upon stimulation of adenylate cyclase with glucagon, forskolin and F- in membranes isolated from cells cultured with 100 mM-ethanol for 48 h. However, no differences were observed in basal and MnCl2-stimulated adenylate cyclase activity. The quantity of alpha i protein was decreased by 35% after chronic ethanol treatment, but no change in the quantity of alpha s protein was detected. Decreased alpha i protein was associated with a decrease in G(i) function, as assessed by the ability of 0.1 nM-guanosine 5'-[beta gamma-imido]triphosphate and 1 microM-somatostatin to inhibit forskolin-stimulated adenylate cyclase activity. Taken together, these results suggest that chronic exposure to ethanol increases receptor-dependent cAMP production in hepatocytes by decreasing the quantity of alpha i protein at the plasma membrane and thereby decreasing the inhibitory effects of G(i) on adenylate cyclase activity. Images Fig. 4.

Nagy, L E; DeSilva, S E

1992-01-01

318

Identification of electrostatic interaction sites between the regulatory and catalytic subunits of cyclic AMP-dependent protein kinase.  

PubMed Central

Two classes of molecules inhibit the catalytic subunit (C) of the cyclic AMP-dependent protein kinase (cAPK), the heat-stable protein kinase inhibitors (PKIs) and the regulatory (R) subunits. Basic sites on C, previously identified as important for R/C interaction in yeast TPK1 and corresponding to Lys213, Lys217, and Lys189 in murine C alpha, were replaced with either Ala or Thr and characterized for their kinetic properties and ability to interact with RI and PKI. rC(K213A) and rC(K217A) were both defective in forming holoenzyme with RI but were inhibited readily with PKI. This contrasts with rC(R133A), which is defective in binding PKI but not RI (Wen & Taylor, 1994). Thus, the C-subunit employs two distinct electrostatic surfaces to achieve high-affinity binding with these two types of inhibitory molecules even though all inhibitors share a common consensus site that occupies the active site cleft. Unlike TPK1, mutation of Lys189 had no effect. The mutant C subunits that were defective in binding RI, rC(K213A) and rC(K217A), were then paired with three RI mutants, rRI(D140A), rRI(E143A), and rRI(D258A), shown previously to be defective in recognition of C. Although the mutations at Asp140 and Asp258 in RI were additive with respect to the C mutations. rC(K213A) and rRI(E143A) were compensatory, thus identifying a specific electrostatic interaction site between RI and C. The results are discussed in terms of the RI and C crystal structures and the sequence homology between the yeast and mammalian enzymes.

Gibson, R. M.; Ji-Buechler, Y.; Taylor, S. S.

1997-01-01

319

Reversal of TGF-?1 stimulation of ?-smooth muscle actin and extracellular matrix components by cyclic AMP in Dupuytren's - derived fibroblasts  

PubMed Central

Background Myofibroblasts, a derived subset of fibroblasts especially important in scar formation and wound contraction, have been found at elevated levels in affected Dupuytren's tissues. Transformation of fibroblasts to myofibroblasts is characterized by expression of alpha- smooth muscle actin (?-SMA) and increased production of extracellular matrix (ECM) components, both events of relevance to connective tissue remodeling. We propose that increasing the activation of the cyclic AMP (cAMP)/protein kinase A signaling pathway will inhibit transforming growth factor-beta1 (TGF-?1)-induced ECM synthesis and myofibroblast formation and may provide a means to blunt fibrosis. Methods Fibroblasts derived from areas of Dupuytren's contracture cord (DC), from adjacent and phenotypically normal palmar fascia (PF), and from palmar fascia from patients undergoing carpal tunnel release (CTR; CT) were treated with TGF-?1 (2 ng/ml) and/or forskolin (10 ?M) (a known stimulator of cAMP). Total RNA and protein extracted was subjected to real time RT-PCR and Western blot analysis. Results The basal mRNA expression levels of fibronectin- extra domain A (FN1-EDA), type I (COL1A2) and type III collagen (COL3A1), and connective tissue growth factor (CTGF) were all significantly increased in DC- and in PF-derived cells compared to CT-derived fibroblasts. The TGF-?1 stimulation of ?-SMA, CTGF, COL1A2 and COL3A1 was greatly inhibited by concomitant treatment with forskolin, especially in DC-derived cells. In contrast, TGF-?1 stimulation of FN1-EDA showed similar levels of reduction with the addition of forskolin in all three cell types. Conclusion In sum, increasing cAMP levels show potential to inhibit the formation of myofibroblasts and accumulation of ECM components. Molecular agents that increase cAMP may therefore prove useful in mitigating DC progression or recurrence.

2011-01-01

320

Effects of thyroid-stimulating hormone on adenyl cyclase activity and intermediary metabolism of "cold" thyroid nodules and normal human thyroid tissue  

PubMed Central

“Cold” thyroid nodules do not concentrate 131I before or after thyrotropin (TSH) administration. In an attempt to elucidate the reason for this TSH unresponsiveness, the effect of TSH in vitro on several metabolic parameters was studied in 11 “cold” thyroid adenomas, 2 medullary carcinomas, and in the surrounding normal thyroid tissue. Basal adenyl cyclase activity, glucose-1-14C oxidation, and 32P incorporation into phospholipids were significantly greater in the adenomas than in the adjacent normal thyroid; basal cyclic 3?,5?-adenosine monophosphate (cyclic AMP) concentration and adenine-3H incorporation into 3H-labeled cyclic AMP were not different. In adenomas as well as normal thyroid, all parameters responded significantly to in vitro TSH stimulation. The response to TSH of adenyl cyclase activity and 32P incorporation was enhanced in adenomas compared with that of the adjacent normal thyroid. These differences were not explained by an increased cellularity of the adenomas. Medullary carcinomas did not respond to TSH in any of the above parameters. The studies demonstrate an intact, TSH-responsive adenyl cyclase-cyclic AMP system in the adenomas and, accordingly, imply the presence of receptor sites for TSH on the cells of the adenoma. The failure of such nodules to concentrate 131I may be owing to a subsequent impairment in the expression of cyclic AMP action on iodine metabolism. Images

DeRubertis, Frederick; Yamashita, Kamejiro; Dekker, Andrew; Larsen, P. Reed; Field, James B.

1972-01-01

321

Genetic Interactions of the E3 Ubiquitin Ligase Component FbxA with Cyclic AMP Metabolism and a Histidine Kinase Signaling Pathway during Dictyostelium discoideum Development  

PubMed Central

Dictyostelium discoideum amoebae with an altered fbxA gene, which is thought to encode a component of an SCF E3 ubiquitin ligase, have defective regulation of cell type proportionality. In chimeras with wild-type cells, the mutant amoebae form mainly spores, leaving the construction of stalks to wild-type cells. To examine the role of fbxA and regulated proteolysis, we have recovered the promoter of fbxA and shown that it is expressed in a pattern resembling that of a prestalk-specific gene until late in development, when it is also expressed in developing spore cells. Because fbxA cells are developmentally deficient in pure culture, we were able to select suppressor mutations that promote sporulation of the original mutant. One suppressor mutation resides within the gene regA, which encodes a cyclic AMP (cAMP) phosphodiesterase linked to an activating response regulator domain. In another suppressor, there has been a disruption of dhkA, a gene encoding a two-component histidine kinase known to influence Dictyostelium development. RegA appears precociously and in greater amounts in the fbxA mutant than in the wild type, but in an fbxA/dhkA double mutant, RegA is restored to wild-type levels. Because the basis of regA suppression might involve alterations in cAMP levels during development, the concentrations of cAMP in all strains were determined. The levels of cAMP are relatively constant during multicellular development in all strains except the dhkA mutant, in which it is reduced at least sixfold. The level of cAMP in the double mutant dhkA/fbxA is relatively normal. The levels of cAMP in the various mutants do not correlate with spore formation, as would be expected on the basis of our present understanding of the signaling pathway leading to the induction of spores. Altered amounts of RegA and cAMP early in the development of the mutants suggest that both fbxA and dhkA genes act earlier than previously thought.

Tekinay, Turgay; Ennis, Herbert L.; Wu, Mary Y.; Nelson, Margaret; Kessin, Richard H.; Ratner, David I.

2003-01-01

322

Regulation of the inflammatory response of vascular endothelial cells by EPAC1  

PubMed Central

Life-threatening diseases of the cardiovascular system, like atherosclerosis, are exacerbated by unwanted inflammation within the structures of large blood vessels. This inflammation involves increased permeability of the vascular endothelial cells (VECs) that form the lining of blood vessels, leading to exaggerated extravasation of blood components and accumulation of fluid in the extravascular space. This results in tissue dysfunction and increased secretion of chemokines that attract leukocytes and monocytes to the inflamed endothelium. Cyclic AMP is synthesized in VECs in response to endogenous Gs-coupled receptors and is known to limit cytokine action and reduce endothelial hyperpermeability induced by multiple pro-inflammatory stimuli. The mechanisms underlying this anti-inflammatory action of cyclic AMP are now being elucidated and it is becoming clear that the cyclic AMP sensor, exchange protein activated by cyclic AMP (EPAC1), appears to play a key role in suppressing unwanted inflammation. EPAC1 mediates at least three anti-inflammatory pathways in VECs by down-regulating inflammatory signalling through the induction of the suppressors of cytokine signalling 3 (SOCS-3) gene, limiting integrin-dependent vascular permeability and enhancing endothelial barrier function through the stabilization of VE-cadherin junctions. Given that manipulation of cellular cyclic AMP levels currently forms the basis of many effective pharmaceuticals and that EPAC1 is involved in multiple anti-inflammatory protective processes in VECs, does this make EPAC1 an attractive target for the development of activators capable of eliciting a coordinated programme of ‘protection’ against the development of endothelial dysfunction? Here we discuss whether EPAC1 represents an attractive therapeutic target for limiting endothelial dysfunction associated with cardiovascular diseases like atherosclerosis. LINKED ARTICLES This article is part of a themed section on Novel cAMP Signalling Paradigms. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.166.issue-2

Parnell, Euan; Smith, Brian O; Palmer, Timothy M; Terrin, Anna; Zaccolo, Manuela; Yarwood, Stephen J

2012-01-01

323

Sensitization of adenylate cyclase: A general mechanism of neuroadaptation to persistent activation of G? i\\/o-coupled receptors?  

Microsoft Academic Search

Acute activation of G?s-coupled receptors stimulates cyclic AMP accumulation leading to the activation of downstream signaling cascades. These G?s-mediated events can be countered by acute activation of inhibitory G proteins (G?i\\/o), which inhibit the activity of adenylate cyclase, thereby attenuating cyclic AMP accumulation. Furthermore, an additional, less direct mechanism for G?i\\/o proteins modulation of cyclic AMP signaling also has been

Christopher A Johnston; Val J Watts

2003-01-01

324

The Role of Cyclic AMP in Normalizing the Function of Engineered Human Blood Microvessels in Microfluidic Collagen Gels  

PubMed Central

Nearly all engineered tissues must eventually be vascularized to survive. To this end, we and others have recently developed methods to synthesize extracellular matrix-based scaffolds that contain open microfluidic networks. These scaffolds serve as templates for the formation of endothelial tubes that can be perfused; whether such microvascular structures are stable and/or functional is largely unknown. Here, we show that compounds that elevate intracellular concentrations of the second messenger cyclic AMP (cAMP) strongly normalize the phenotype of engineered human microvessels in microfluidic type I collagen gels. Cyclic AMP-elevating agents promoted vascular stability and barrier function, and reduced cellular turnover. Under conditions that induced the highest levels of cAMP, the physiology of engineered microvessels in vitro quantitatively mirrored that of native vessels in vivo. Computational analysis indicated that cAMP stabilized vessels partly via its enhancement of barrier function.

Wong, Keith H. K.; Truslow, James G.; Tien, Joe

2010-01-01

325

Effects of chronic treatment with a cyclic AMP-selective phosphodiesterase inhibitor, rolipram, on excitatory amino acid neurotransmission systems in young and aged rat brains  

Microsoft Academic Search

Summary Rolipram selectively inhibits cyclic AMP-specific phosphodiesterase, and leads to an increase in cyclic AMP levels in the brain. In this study, we investigated the effects of chronic rolipram treatment on excitatory and inhibitory amino acid neurotransmission systems in young and aged Wistar rat brains. We used in vitro autoradiography with [3H]MK-801, [3H]glycine, D-[3H]aspartate, and [3H]muscimol to label N-methyl-D-aspartate (NMDA)

H. Kato; T. Araki; T. Chen; X.-H. Liu; T. Hiranuma; K. Murase; Y. Itoyama; K. Kogure

1997-01-01

326

Effects of Cyclic AMP on Expression of Myelin Genes in the N20.1 Oligodendroglial Cell Line  

Microsoft Academic Search

The N20.1 immortalized cell line has several characteristics of differentiating oligodendrocytes (OLs), including expression of the glycolipids galactocerebroside (GalC) and sulfatide, and the myelin proteins CNPase and myelin basic protein (MBP) (1,2). Addition of 1–100 µM forskolin to elevate cyclic AMP (cAMP) levels changed cell morphology from irregular and flattened to a more rounded birefringent cell with multiple branched processes.

Diane M. Studzinski; Radhika Ramaswamy; Joyce A. Benjamins

1998-01-01

327

Role of the cyclic AMP-dependent pathway in free radical-induced cholesterol accumulation in vascular smooth muscle cells  

Microsoft Academic Search

We have previously reported that free radical-treated vascular smooth muscle cells (SMC) lead to cholesterol accumulation in vitro. In the current study, we investigated the effects of oxidative stress on cyclic AMP concentration and cAMP-dependent enzymes involved in cholesterol homeostasis in A7r5 cells. Under our conditions of a mild oxidative stress, namely with no change in cell viability, we found

Laurence Gesquière; Nadine Loreau; Denis Blache

2000-01-01

328

Decrease in thromboxane A 2 receptor expression by differentiation with dibutyryl cyclic AMP in 1321N1 human astrocytoma cells  

Microsoft Academic Search

Thromboxane A2 (TXA2) receptor expression with its signaling was investigated in 1321N1 human astrocytoma cells differentiated with dibutyryl cyclic AMP (dbcAMP). The cells cultured in 0.5% fetal calf serum containing 0.5 mM dbcAMP for 3 days showed the star-shaped morphology, accompanied with the reduction of a TXA2 mimetic U46619-induced phosphoinositide hydrolysis and Ca2+ mobilization. Immunoblotting analysis revealed that human astrocytoma

Shigeyoshi Honma; Norimichi Nakahata; Hiroshi Kobayashi; Shizuyo Ikeda; Noriko Takeda; Yasushi Ohizumi

1999-01-01

329

Comparisons between the antianesthetic action of dibutyryl cyclic AMP and analeptic drugs on amobarbital-induced narcosis in the rat.  

PubMed

The dose-related antianesthetic and antidotal property of dibutyryl cyclic AMP, devoid of toxic effects, imparts uniqueness to the nucleotide as an arousal agent. Of the analeptic drugs studied (d-amphetamine, picrotoxin, pentylenetetrazol, caffeine, theophylline, strychnine, ethamivan and doxapram), only picrotoxin demonstrated antianesthetic properties. However, picrotoxin was associated with severe toxicity at all dose levels tested. No analeptic drug is effective in reversing the central nervous system depression produced by sedative, hypnotic or tranquilizer drug overdosage. PMID:8796

Kraynack, B J; Cohn, M L; Cohn, M; Taylor, F H

1976-01-01

330

Pde1 Phosphodiesterase Modulates Cyclic AMP Levels through a Protein Kinase A-Mediated Negative Feedback Loop in Cryptococcus neoformans  

Microsoft Academic Search

Received 25 July 2005\\/Accepted 20 September 2005 The virulence of the human pathogenic fungus Cryptococcus neoformans is regulated by a cyclic AMP (cAMP)-dependent protein kinase A (PKA) signaling cascade that promotes mating and the production of melanin and capsule. In this study, genes encoding homologs of the Saccharomyces cerevisiae low- and high- affinity phosphodiesterases, PDE1 and PDE2, respectively, were deleted

Julie K. Hicks; Yong-Sun Bahn; Joseph Heitman

2005-01-01

331

An EAL domain protein and cyclic AMP contribute to the interaction between the two quorum sensing systems in Escherichia coli  

Microsoft Academic Search

Quorum sensing (QS) is a bacterial cell-cell communication process by which bacteria communicate using extracellular signals called autoinducers. Two QS systems have been identified in Escherichia coli K-12, including an intact QS system 2 that is stimulated by the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex and a partial QS system 1 that consists of SdiA (suppressor of cell division

Xianxuan Zhou; Xiaoming Meng; Baolin Sun

2008-01-01

332

Role of Ecdysone, Pupariation Factors, and Cyclic AMP in Formation and Tanning of the Puparium of the Fleshfly Sarcophaga bullata  

Microsoft Academic Search

Two pupariation factors, anterior retraction factor (ARF) and puparium tanning factor (PTF), are absent from the hemolymph of larvae at the time of tanning accelerated by ARF\\/PTF, cyclic AMP, or dopamine. ARF and PTF are not involved in derepression of dopa decarboxylase (aromatic L-amino-acid decarboxylase, aromatic L-amino-acid carboxy-lyase, EC 4.1.1.28) synthesis initiated by ecdysone. Tanning is entirely inhibited by injection

Morris Seligman; Ann Blechl; James Blechl; Paul Herman; G. Fraenkel

1977-01-01

333

Heat shock protein 72 restores cyclic AMP accumulation after heat shock in N18TG2 cells  

Microsoft Academic Search

Although there are several reports on the alteration of intracellular signal transduction during heat shock in somatic cells, the long term effects of heat shock on neuronal cells remain unknown. In this report, we investigated cyclic AMP (cAMP) accumulation and the expression of heat shock proteins following heat shock in mouse neuroblastoma N18TG2 cells. Basal cAMP accumulation, or that stimulated

Hidenobu Zensho; Akira Nishida; Masami Shimizu; Yousuke Uchitomi; Shigeto Yamawaki

1998-01-01

334

Intracellular cyclic AMP concentration is decreased in Salmonella typhimurium fur mutants.  

PubMed

It is known that the Fur protein negatively regulates iron-uptake systems in different bacterial species, including Salmonella typhimurium. In this study it has been shown that the intracellular concentration of cyclic AMP (cAMP) is lower in a knockout S. typhimurium fur mutant than in the wild-type strain. According to this, the expression of two cAMP-regulated genes, such as pepE (encoding an alpha-aspartyl dipeptidase) and the Escherichia coli lac operon, is decreased in S. typhimurium fur cells in comparison with wild-type cells. Introduction of an additional mutation in cpdA, encoding a cyclic 3',5'-cAMP phosphodiesterase, recovers wild-type intracellular cAMP concentration in the S. typhimurium fur mutant. Likewise, expression of pepE and the E. coli lac operon was the same in the S. typhimurium fur cpdA double mutant and the wild-type strain. Moreover, these results also demonstrate that the S. typhimurium Fur protein positively regulates the expression of the flhD master operon governing the flagellar regulon. This positive control must be mediated by binding of the S. typhimurium Fur protein to the flhD promoter as indicated by the fact that this promoter tests positive in a Fur titration assay. PMID:11932449

Campoy, Susana; Jara, Mónica; Busquets, Núria; de Rozas, Ana M Pérez; Badiola, Ignacio; Barbé, Jordi

2002-04-01

335

Effect of Cyclic AMP on Barrier Function of Human Lymphatic Microvascular Tubes1  

PubMed Central

This work examines the effect of cyclic AMP (cAMP) on the in vitro barrier function of tubes of human dermal lymphatic microvascular endothelial cells (LECs). Under baseline conditions, the barrier function of LEC tubes was weak, with diffusional permeability coefficients to bovine serum albumin and 10 kDa dextran of 1.4?0.6+0.9×10?6 cm/s and 1.7?0.5+0.8×10?6 cm/s (geometric mean ± 95% CI), respectively, and 1.2 ± 0.5 (mean ± 95% CI) focal leaks per mm. Exposure to low concentrations (3 ?M) of a cell-permeant analog of cAMP did not alter the barrier function. Exposure to higher concentrations (80 and 400 ?M) and/or the phosphodiesterase inhibitor Ro-20?1724 (20 ?M) lowered permeabilities and the number of focal leaks, and increased the selectivity of the barrier. Decreased permeabilities were accompanied by an increase in continuous VE-cadherin staining at cell-cell borders. Exposure to 1 mM 2?,5?-dideoxyadenosine, an inhibitor of adenylate cyclase, did not increase permeabilities. LECs expressed the lymphatic-specific master transcription factor Prox-1, regardless of whether barrier function was weak or strong. Our results indicate that the permeability of LEC tubes in vitro responds to cAMP in a manner similar to that well-described for the permeability of blood microvessels.

Price, Gavrielle M.; Chrobak, Kenneth M.; Tien, Joe

2008-01-01

336

CREB and the CRTC co-activators: sensors for hormonal and metabolic signals  

Microsoft Academic Search

The cyclic AMP-responsive element-binding protein (CREB) is phosphorylated in response to a wide variety of signals, yet target gene transcription is only increased in a subset of cases. Recent studies indicate that CREB functions in concert with a family of latent cytoplasmic co-activators called cAMP-regulated transcriptional co-activators (CRTCs), which are activated through dephosphorylation. A dual requirement for CREB phosphorylation and

Judith Y. Altarejos; Marc Montminy

2011-01-01

337

Ability of E. coli cyclic AMP receptor protein to differentiate cyclic nucelotides: effects of single site mutations.  

PubMed

Escherichia coli cyclic AMP receptor protein (CRP) is a global transcriptional regulator which controls the expression of many different genes. Although different cyclic nucleotides can bind to CRP with almost equal affinity, only in the presence of cAMP could wild-type CRP bind to specific DNA sequences. Molecular genetic studies have identified a class of mutants, CRP*, which either do not require exogenous cAMP for activation or can be activated by cGMP. Thus, these mutants might aid in identifying the structural elements that are involved in the modulation of CRP to correctly differentiate the messages embedded in cyclic nucleotides. In this in vitro study, five CRP* mutants, namely, D53H, S62F, G141Q, G141K, and L148R, were tested for their abilities to bind the lac promoter sequence and the effects of cyclic nucleotides in modulating DNA sequence recognition. For comparison, non-CRP* mutants K52N, T127L, H159L, and K52N/H159L were studied. cCMP and cGMP can replace cAMP as an allosteric effector in all of these CRP mutants except S62F and non-CRP* mutants. The D53H, G141Q, G141K, and L148R mutants exhibit significantly higher affinity for the lac promoter sequence than wild-type CRP while S62F and the non-CRP* mutants exhibit reduced affinity. To probe the pathway of communication, the energetics of subunit assembly in these mutants were monitored by sedimentation equilibrium, and the conformational states of these mutants were probed by proteolysis and accessibility of Cys178 to chemical modifications. Results from these studies imply that signals due to mutations are mostly transmitted through the subunit interface. Thus, residues in CRP outside of the cyclic nucleotide binding site modulate the ability of CRP to differentiate these three cyclic nucleotides through long-range communication. Furthermore, this study shows that CRP* mutations do not impart any unique properties to CRP except that the DNA binding constants are shifted to a regime of higher affinity. PMID:11863432

Lin, Shwu-Hwa; Kovac, Lubomir; Chin, Anita J; Chin, Christopher C Q; Lee, J Ching

2002-03-01

338

Cyclic AMP levels during induction and repression of cellulase biosynthesis in Thermomonospora curvata  

SciTech Connect

Specific cellulase production rates (SCPR) were compared with intracellular cyclic AMP (cAMP) levels in the thermophilic actinomycete, Thermomonospora curvata, during growth on several carbon sources in a chemically defined medium. SCPR and cAMP levels were 0.03 U (endoglucanase (EG) units) and 2 pmol per mg of dry cells, respectively, during exponential growth on glucose. These values increased to about 6 and 25, respectively, during growth on cellulose. Detectable EG production ceased when cAMP levels dropped below 10. Cellobiose (usually considered to be a cellulase inducer) caused a sharp decrease in cAMP levels and repressed EG production when added to cellulose-grown cultures. 2-deoxy-D-glucose, although nometabolizable in T. curvata, depressed cAMP to levels observed with glucose, but unlike glucose, the 2DG effect persisted until cells were washed and transferred to fresh medium. SCPR values and cAMP levels in cells grown in continuous culture under conditions of cellobiose limitation were markedly influenced by dilution rate (D). The maxima for both occurred at D = 0.085 (culture generation time of 11.8 h). When D was held constant and cellobiose concentration was increased over a 14-fold range to support higher steady state population levels, SCPR values decreased about fivefold, indicating that extracellular catabolite accumulation may be a factor in EG repression. The role of cAMP in the mechanism of this repression appears to be neither simple nor direct, since large changes (up to 200-fold) in SCPR accompany relatively small changes (10-fold) in cellular cAMP levels.

Wood, W.E.; Neubauer, D.G.; Stutzenberger, F.J.

1984-12-01

339

Regulation of osteosarcoma EGF receptor affinity by phorbol ester and cyclic AMP  

SciTech Connect

We studied the binding and degradation of 125I-labeled epidermal growth factor (EGF) by UMR-106 osteosarcoma cells and the regulation of EGF receptor affinity for EGF by the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and by treatments that raise intracellular levels of cyclic AMP. Cell surface binding of (125I)EGF to A431 cells reached a plateau after a 30 minute incubation at 37 degrees C but was undetectable in UMR-106 cells. Degradation of (125I)EGF proceeded at a 50-fold higher rate in A431 cells on a per cell basis, but receptor-bound (125I)EGF was internalized and degraded at a 3.5-fold higher rate by UMR-106 cells on a per receptor basis. At 4 degrees C, (125I)EGF labeled a single class of surface binding sites in the UMR-106 cell. Treatment with TPA at 37 degrees C reduced subsequent cell surface binding of (125I)EGF at 4 degrees C a maximum of 80% with an IC50 of 1.25 ng/ml. Maximal TPA reduction of (125I)EGF binding was observed within 5-15 minutes and was due to a reduction in the affinity of cell surface receptors of (125I)EGF without a change in receptor density. Pretreatment of the cells for 4 h with 30 microM forskolin, 1 mM isobutylmethylxanthine (IBMX) plus 30 microM forskolin, or 1 mM IBMX plus 100 ng/ml parathyroid hormone (PTH) attenuated the loss in (125I)EGF binding caused by a subsequent dose of 10 ng/ml of TPA by 17% (p less than 0.0005), 39% (p less than 0.0002), and 35% (p less than 0.002), respectively.

Borst, S.E.; Catherwood, B.D. (Emory Univ. Department of Medicine, Atlanta, GA (USA))

1989-04-01

340

The Cyclic AMP Cascade Is Altered in the Fragile X Nervous System  

PubMed Central

Fragile X syndrome (FX), the most common heritable cause of mental retardation and autism, is a developmental disorder characterized by physical, cognitive, and behavioral deficits. FX results from a trinucleotide expansion mutation in the fmr1 gene that reduces levels of fragile X mental retardation protein (FMRP). Although research efforts have focused on FMRP's impact on mGluR signaling, how the loss of FMRP leads to the individual symptoms of FX is not known. Previous studies on human FX blood cells revealed alterations in the cyclic adenosine 3?, 5?-monophosphate (cAMP) cascade. We tested the hypothesis that cAMP signaling is altered in the FX nervous system using three different model systems. Induced levels of cAMP in platelets and in brains of fmr1 knockout mice are substantially reduced. Cyclic AMP induction is also significantly reduced in human FX neural cells. Furthermore, cAMP production is decreased in the heads of FX Drosophila and this defect can be rescued by reintroduction of the dfmr gene. Our results indicate that a robust defect in cAMP production in FX is conserved across species and suggest that cAMP metabolism may serve as a useful biomarker in the human disease population. Reduced cAMP induction has implications for the underlying causes of FX and autism spectrum disorders. Pharmacological agents known to modulate the cAMP cascade may be therapeutic in FX patients and can be tested in these models, thus supplementing current efforts centered on mGluR signaling.

Kelley, Daniel J.; Davidson, Richard J.; Elliott, Jamie L.; Lahvis, Garet P.; Yin, Jerry C. P.; Bhattacharyya, Anita

2007-01-01

341

Regulation of Na(+)-coupled glucose transport in LLC-PK1 cells. Message stabilization induced by cyclic AMP elevation is accompanied by binding of a M(r) = 48,000 protein to a uridine-rich domain in the 3'-untranslated region.  

PubMed

In an exploration of the molecular basis of cyclic AMP-induced stabilization of Na+/glucose cotransporter mRNA (SGLT1 isoform) accompanying cell differentiation in the pig kidney cell line LLC-PK1, we have identified a 48-kDa cytoplasmic protein factor, designated SG-URBP, which specifically binds a 120-nucleotide sequence within the 3'-untranslated region of the SGLT1 message. A 46-nucleotide uridine-rich element within this region appears necessary for specific binding, and the presence of the 3'-untranslated region is necessary for message stabilization by cyclic AMP. The binding activity of SG-URBP is up-regulated after cyclic AMP elevation and protein kinase A activation, whereas protein dephosphorylation either in vivo or in vitro is associated with loss of binding activity. The increase in SG-URBP binding activity correlates with an increase in the half-life of the SGLT1 message, suggesting a cause and effect relationship. PMID:7592596

Peng, H; Lever, J E

1995-10-13

342

Studies on the Mechanism of Phosphorylation of Synthetic Polypeptides by a Calf Thymus Cyclic AMP-Dependent Protein Kinase  

Microsoft Academic Search

Synthetic polypeptides were employed as substrates in kinetic analyses of the reaction mechanism for the catalytic subunit of a cyclic AMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) from calf thymus. This enzyme preparation was shown to catalyze the transfer of phosphate from ATP to histone H1 from calf thymus, as well as to two synthetic polypeptides, Arg-Lys-Ala-Ser-Gly-Pro (H1-6) and Arg-Arg-Lys-Ala-Ser-Gly-Pro

Arthur H. Pomerantz; Vincent G. Allfrey; R. B. Merrifield; Edward M. Johnson

1977-01-01

343

Agonist trafficking of Gi/o-mediated ?2A-adrenoceptor responses in HEL 92.1.7 cells  

PubMed Central

The ability of 19 agonists to elevate Ca2+ and inhibit forskolin-induced cyclic AMP elevation through ?2A-adrenoceptors in HEL 92.1.7 cells was investigated. Ligands of catecholamine-like- (five), imidazoline- (nine) and non-catecholamine-non-imidazoline-type (five) were included. The relative maximum responses were similar in both assays. Five ligands were full or nearly full agonists, six produced 20?–?70% of the response to a full agonist and the remaining eight gave lower responses (<20%) so that their potencies were difficult to evaluate. Marked differences in the potencies of the agonists with respect to the two measured responses were seen. The catecholamines were several times less potent in decreasing cyclic AMP than in increasing Ca2+, whereas the other, both imidazoline and ox-/thiazoloazepine ligands, were several times more potent with respect to the former than the latter response. For instance, UK14,304 was more potent than adrenaline with respect to the cyclic AMP response but less potent than adrenaline with respect to the Ca2+ response. All the responses were sensitive to pertussis toxin-pretreatment. Also the possible role of PLA2, ?-adrenoceptors or ligand transport or metabolism as a source of error could be excluded. The results suggest that the active receptor states produced by catecholamines and the other agonists are markedly different and therefore have different abilities to activate different signalling pathways.

Kukkonen, Jyrki P; Jansson, Christian C; Akerman, Karl E O

2001-01-01

344

Chromatin-Dependent Cooperativity between Constitutive and Inducible Activation Domains in CREB  

Microsoft Academic Search

The cyclic AMP (cAMP)-responsive factor CREB induces target gene expression via constitutive (Q2) and inducible (KID, for kinase-inducible domain) activation domains that function synergistically in response to cellular signals. KID stimulates transcription via a phospho (Ser133)-dependent interaction with the coacti- vator paralogs CREB binding protein and p300, whereas Q2 recruits the TFIID complex via a direct associ- ation with hTAFII130.

HIROSHI ASAHARA; BUYUNG SANTOSO; ERNESTO GUZMAN; KEYONG DU; PHILIP A. COLE; IRWIN DAVIDSON; MARC MONTMINY

2001-01-01

345

A Model for cAMP-mediated cGMP Response in Dictyostelium discoideum  

Microsoft Academic Search

In Dictyostelium discoideum extracellular cyclic AMP (cAMP), as shown by previous studies, induces a transient accumulation of intracellular cyclic guanosine-5'-monophosphate (cGMP), which peaks at 10 s and recovers basal levels at 30 s after stimulation, even with persistent cAMP stimulation. Additional investigations have shown that the cAMP-mediated cGMP response is built up from surface cAMP receptor-mediated activation of guanylyl cyclase

Romi Valkema; Peter J. M. van Haastert

1994-01-01

346

Effect of cyclic AMP and prostaglandin E2 on the induction of nitric oxide- and prostanoid-forming pathways in cultured rat mesangial cells.  

PubMed Central

Cyclic AMP (cAMP) represents an important cellular signalling molecule. We analysed the effect of dibutyryl cAMP (db-cAMP), a cell-permeable and stable derivative of cAMP, on the regulation and expression of cyclo-oxygenase 2, inducible NO synthase and argininosuccinate synthetase. We observed different transcriptional regulation of these enzymes depending on the db-cAMP concentration used. Low concentrations of db-cAMP in the range 10-50 microM elevated levels of cyclo-oxygenase 2 mRNA, protein and activity, but not the respective mRNA and protein concentrations of the inducible NO synthase or argininosuccinate synthetase. At higher concentrations a massive induction of the latter two enzymes was also apparent. Expression of prostacyclin synthase and argininosuccinate lyase, secondary enzymes of NO- and prostanoid-forming pathways, was not stimulated by db-cAMP. Prostaglandin E2, known to be an intracellular physiological trigger of cAMP formation, stimulated only cyclooxygenase 2 expression and activity at a concentration of 10 microM, and not inducible NO synthase. The induction of the mRNA for the transcription factors JunB and p65, a component of the NF kappa B complex, by prostaglandin treatment of the cells might be a possible mechanistic explanation for this observation.

Nusing, R M; Klein, T; Pfeilschifter, J; Ullrich, V

1996-01-01

347

[The role of gonadotropins, cyclic AMP, 22-R-OH-cholesterol and cofactors in regulating endocrine functions of the Leydig cells in rats. III. Mechanisms responsible for "desensitization" of the Leydig cells of rats caused by high doses of hCG].  

PubMed

Two groups of rats (a control group and the group examined) were administered intraperitoneally supraphysiological doses of hCG in order to induce a "down regulation" effect on the level of receptors LH and to achieve the desensibilization of Leydig cells. The authors tried to find out at which stage of sequence of changes from receptor stimulation to hormone production there appears a state of cellular resistance to further stimulation. Sections of the nucleus were incubated with various substances influencing steridogenesis (LH, hCG, dbcAMP, 22-R-OH-cholesterol, NAD + NADP + G-6-P + G-6-PDH). An index of the influence of the above substances on the synthesis of androgens were amounts of pregnenolon as the first and testosterone as the final stage of hormonal changes marked radioimmunologically in nucleus homogenates and incubating media. It was shown that the resistance of Leydig cells to further stimulation in the group of animals that were given high doses of hCG is the result of enzymatic blocks in testosterone synthesis. The first block is "late" block of 17 alpha-hydroxylase and 17-20 desmolase, disturbing transforming of 21-carbon steriods into 19-carbon androgens. When the dose of hCG increases, there appears the second block, the so called "early" block, disturbing mitochondrial synthesis of pregnenolon. It was found that exogenic cofactors are in a position, at least partially, to restore the activity of blocked enzymes.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2561360

Grochowski, D; Szamatowicz, M

1989-05-01

348

Genome-Wide Identification of In Vivo Binding Sites of GlxR, a Cyclic AMP Receptor Protein-Type Regulator in Corynebacterium glutamicum?†  

PubMed Central

Corynebacterium glutamicum GlxR is a cyclic AMP (cAMP) receptor protein-type regulator. Although over 200 GlxR-binding sites in the C. glutamicum genome are predicted in silico, studies on the physiological function of GlxR have been hindered by the severe growth defects of a glxR mutant. This study identified the GlxR regulon by chromatin immunoprecipitation in conjunction with microarray (ChIP-chip) analyses. In total, 209 regions were detected as in vivo GlxR-binding sites. In vitro binding assays and promoter-reporter assays demonstrated that GlxR directly activates expression of genes for aerobic respiration, ATP synthesis, and glycolysis and that it is required for expression of genes for cell separation and mechanosensitive channels. GlxR also directly represses a citrate uptake gene in the presence of citrate. Moreover, ChIP-chip analyses showed that GlxR was still able to interact with its target sites in a mutant with a deletion of cyaB, the sole adenylate cyclase gene in the genome, even though binding affinity was markedly decreased. Thus, GlxR is physiologically functional at the relatively low cAMP levels in the cyaB mutant, allowing the cyaB mutant to grow much better than the glxR mutant.

Toyoda, Koichi; Teramoto, Haruhiko; Inui, Masayuki; Yukawa, Hideaki

2011-01-01

349

Cloning and expression of cDNA for a human low-K sub m , rolipram-sensitive cyclic AMP phosphodiesterase  

SciTech Connect

The authors have isolated cDNA clones representing cyclic AMP (cAMP)-specific phosphodiesterases (PDEases) from a human monocyte cDNA library. One cDNA clone (hPDE-1) defines a large open reading frame of ca. 2.1 kilobases, predicting a 686-amino-acid, ca. 77-kilodalton protein which contains significant homology to both rat brain and {ital Drosophila} cAMP PDEases, especially within an internal conserved domain of ca. 270 residues. Amino acid sequence divergence exists at the NH{sub 2} terminus and also within a 40- to 100-residue domain near the COOH-terminal end. hPDE-1 hybridizes to a major 4.8-kilobase mRNA transcript from both human monocytes and placenta. The coding region of hPDE-1 was engineered for expression in COS-1 cells, resulting in the overproduction of cAMP PDEase activity. The hPDE-1 recombinant gene product was identified as a low-{ital K{sub m}} cAMP phosphodiesterase on the basis of several biochemical properties including selective inhibition by the antidepressant drug rolipram. Known inhibitors of other PDEases (cGMP-specific PDEase, cGMP-inhibited PDEase) had little or no effect on the hPDE-1 recombinant gene product.

Livi, G.P.; McHale, M.J.; Sathe, G.M.; Taylor, D.P. (Dept. of Gene Expression Sciences, Smithkline Beecham Pharmaceuticals, King of Prussia, PA (US)); Kmetz, P.; Balcarek, J.M. (Dept. of Molecular Genetics, Smithkline Beecham Pharmaceuticals, King of Prussia, PA (US)); Cieslinski, L.B.; Torphy, T.J. (Dept. of Pharmacology, Smithkline Beecham Pharmaceuticals, King of Prussia, PA (US)); Davis, R.L. (Baylor Univ., Houston, TX (USA). Dept. of Cell Biology)

1990-06-01

350

A spontaneous change in the intracellular cyclic AMP level in Aspergillus niger is influenced by the sucrose concentration in the medium and by light.  

PubMed Central

A spontaneous rise in intracellular cyclic AMP (cAMP) levels was observed in the early stages of Aspergillus niger growth under conditions yielding large amounts of citric acid. The amount of cAMP formed was found to depend on the initial concentration of sucrose in the medium. Under higher-sucrose conditions, the cAMP peak appeared earlier and was higher, while in lower-sucrose media a flattened peak was observed later in fermentation. Since in media with higher concentrations of sucrose intracellular citric acid starts to accumulate earlier and more rapidly, cAMP synthesis may be triggered by intracellular acidification, which is caused by the dissociation of citric acid. No spontaneous increase in cAMP concentrations could be detected when the cells were grown in continuously illuminated cultures, suggesting that A. niger phosphodiesterase (PDE) is photoregulated. More evidence for the activation of PDE by light was obtained from morphological studies under light and dark conditions in the presence of cAMP or N6,O2'-dibutyryl cAMP, and this idea was additionally supported by experiments in which PDE inhibitors were tested.

Gradisnik-Grapulin, M; Legisa, M

1997-01-01

351

Engineered deletion of the unique N-terminal domain of the cyclic AMP-specific phosphodiesterase RD1 prevents plasma membrane association and the attainment of enhanced thermostability without altering its sensitivity to inhibition by rolipram.  

PubMed Central

Full-length cDNA for the rat brain rolipram-sensitive cyclic AMP phosphodiesterase (PDE), RD1 was introduced into the expression vector pSVL. COS cells transfected with the recombinant vector pSVL-RD1 exhibited a 30-55% increase in homogenate PDE activity, which was abolished by rolipram (10 microM). Removal of the first 67 nucleotides of the RD1 cDNA yielded a truncated enzyme called Met26-RD1 which lacked the N-terminal first 25 amino acids. Whereas approx. 75% of RD1 activity was membrane-associated, Met26-RD1 activity was found exclusively in the cytosol fraction. Expression of RD1 nearly doubled membrane-associated PDE activity, while expression of Met26-RD1 increased cytosolic activity by approx. 30%. Membrane RD1 activity was found to be primarily associated with the plasma membrane, was not released by either high concentrations of NaCl or by a 'hypotonic shock' treatment, but was solubilized with low concentrations of Triton X-100. Phase separation of membrane components with Triton X-114 showed partition of RD1 into both the aqueous and detergent-rich phases, whereas Met26-RD1 partitioned exclusively into the aqueous phase. Both RD1 and Met26-RD1 specifically hydrolysed cyclic AMP; were unaffected by either Ca2+/calmodulin or by low cyclic GMP concentrations; exhibited linear Lineweaver-Burke plots with similar Km values for cyclic AMP (4 microM); both were potently and similarly inhibited by rolipram (Ki approx. 0.5 microM) and were similarly inhibited by cilostamide and 3-isobutyl-1-methylxanthine. Thermal inactivation, at 50 degrees C, showed that while the cytosolic-located fraction of RD1 (t0.5 approx. 3 min) and Met26-RD1 (t0.5 approx 3 min) were similarly thermolabile, membrane-bound RD1 was considerably more thermostable (t0.5 approx. 11 min). Treatment of both cytosolic RD1 and Met26-RD1 with Triton X-100 did not affect their thermostability, but solubilization of membrane RD1 activity with Triton X-100 markedly decreased its thermostability (t0.5 approx. 5 min). The N-terminal domain of RD1 appears not to influence either the substrate specificity or inhibitor sensitivity of this enzyme, but it does contain information which can allow RD1 to become plasma membrane-associated and thereby adopt a conformation which has enhanced thermostability. Images Figure 1 Figure 2

Shakur, Y; Pryde, J G; Houslay, M D

1993-01-01

352

Generation of Cyclic AMP in Taste Buds of the Rat Circumvallate Papilla in Response to Sucrose  

Microsoft Academic Search

Epithelial sheets rich in taste buds and free of muscle tissue and von Ebner’s washing glands were isolated as a U-shaped cleft which surrounds the circumvallate (CV) papilla of the rat tongue. The sheet of CV tissue from one tongue (total protein content: 8–14 ?g) was cut in two approximately equal parts which were incubated with permeant phosphodiesterase inhibitor (IBMX;

Benjamin J. Striem; Michael Naim; Bernd Lindemann

1991-01-01

353

Impaired cyclic AMP response to stimuli in glucose-desensitized rat pancreatic islets  

Microsoft Academic Search

Isolated islets were either studied immediately after isolation (fresh: F), or were cultured for 6 days at 11 mM glucose (desensitized; D), or were incubated for 2 h at 5.5 mM glucose following D (recovered; R). Glucose-stimulated insulin secretion in D islets was reduced compared with F and R islets. In the presence of 3-isobutyl-1-methylxanthine, glucose also increased cyclic adenosine

S. G. Laychock

1995-01-01

354

The role of protein kinase activation in the control of steroidogenesis by adrenocorticotrophic hormone in the adrenal cortex  

PubMed Central

A method has been developed for investigation of the effect of adrenocorticotrophic hormone (ACTH) on the state of activation of a cyclic AMP-dependent protein kinase within cells of the adrenal cortex. Enzyme activity was measured in terms of the quantity of 32P transferred from [?-32P]ATP to histone under conditions in which bound cyclic AMP did not dissociate from the regulatory subunit of the protein kinase ACTH (1×10?2i.u./ml) caused a rapid and complete activation of the cyclic AMP-dependent protein kinase activity within 2min of hormone addition to the isolated cells. In response to a range of ACTH concentrations a sigmoid log dose–response curve for protein kinase activation was obtained, with half-maximal stimulation attained at about 1×10?3i.u./ml. However, some low doses of ACTH that elicited a marked (but submaximal) steroidogenic response failed to cause a clear stimulation of protein kinase activity in isolated adrenal cells. Theophylline (2mm) potentiated the effect of ACTH on protein kinase activity. The results implicate an important role for protein kinase in ACTH action on the adrenocortical cell.

Richardson, Malcolm C.; Schulster, Dennis

1973-01-01

355

Cyclic AMP-mediated upregulation of the expression of neuronal NO synthase in human A673 neuroepithelioma cells results in a decrease in the level of bioactive NO production: analysis of the signaling mechanisms that are involved.  

PubMed

The expression level of neuronal nitric oxide synthase (nNOS) can vary depending on the (patho)physiological conditions. Here we document a marked induction of nNOS mRNA, protein, and total NO production in response to dibutyryl cyclic AMP (db-cAMP) in human A673 neuroepithelial cells. However, the upregulation of nNOS was associated with a decreased level of production of bioactive NO and by an increase in the level of generation of reactive oxygen species (ROS). ROS production could be prevented by the NOS inhibitor L-NAME, suggesting nNOS itself is involved in ROS generation. Sepiapterin supplementation of db-cAMP-treated A673 cells could restore full bioactive NO production, most likely by preventing the uncoupling of nNOS. nNOS was upregulated by other stable analogues of cAMP, by the activator of adenylyl cyclase forskolin, by isoproterenol or by dopamine through activation of D1 receptors, and by inhibitors of phosphodiesterase. cAMP did not change the half-life of the nNOS mRNA. Inhibitors of protein kinase A (PKA), H-89 and R(p)-cAMPS, produced a partial inhibition of basal and cAMP-induced nNOS expression. cAMP response element binding and modulator transcription factors (CREB and CREM), typical target proteins of PKA, were expressed in A673 cells, as was the coactivator CREB binding protein (CBP). cAMP-stimulated induction of nNOS was significantly enhanced in A673 cells stably transfected with wild-type CREB and almost abolished in cells transfected with KCREB (containing a mutation of the DNA binding domain). In A673 cells transfected with CREB(133) (containing a mutation of the phosphorylatable serine 133), the overall level of nNOS expression was reduced, but the expressional stimulation by cAMP remained. This suggests that CREB bypasses, in part, the classical requirement for phosphorylation and association with CBP. Three members of the recently described four-and-a-half-LIM-domain proteins (FHL1-FHL3) were found to be expressed in A673 cells; FHL-1 and FHL-3 were upregulated by cAMP. These proteins can provide direct activation function to both CREB and CREM, and may be responsible for the PKA-independent component of CREB and CREM activity. PMID:15170357

Boissel, Jean-Paul; Bros, Matthias; Schröck, Andreas; Gödtel-Armbrust, Ute; Förstermann, Ulrich

2004-06-01

356

Selective unresponsiveness to the inhibition of p38 MAPK activation by cAMP helps L929 fibroblastoma cells escape TNF-?-induced cell death  

Microsoft Academic Search

BACKGROUND: The cyclic AMP (cAMP) signaling pathway has been reported to either promote or suppress cell death, in a cell context-dependent manner. Our previous study has shown that the induction of dynein light chain (DLC) by cAMP response element-binding protein (CREB) is required for cAMP-mediated inhibition of mitogen-activated protein kinase (MAPK) p38 activation in fibroblasts, which leads to suppression of

Jing Wang; Ruihong Tang; Ming Lv; Jiyan Zhang; Beifen Shen

2010-01-01

357

Study of enzymes regulating vasopressin-stimulated cyclic AMP metabolism in separated mitochondria-rich and granular epithelial cells of toad urinary bladder  

Microsoft Academic Search

Summary The epithelial cells of the toad urinary bladder are morphologically heterogeneous. In order to relate the effect of vasopressin on cyclic AMP metabolism to cell type, the epithelial cells were separated by the density gradient technique of Scott, Sapirstein and Yoder (Science184: 797, 1974). The separation was verified by electron-microscopy and by observing that the band of cells enriched

J. S. Handler; A. S. Preston

1976-01-01

358

Catalytic unit-independent phosphorylation and dephosphorylation of type II regulatory subunit of cyclic AMP-dependent protein kinase in rat liver plasma membranes.  

PubMed Central

Rat liver plasma membranes contain a 55 kDa protein which proved to be identical with type II regulatory subunit (RII) of the cyclic AMP-dependent protein kinase (kinase A) by several criteria (gel electrophoretic behaviour, peptide map, position of the autophosphorylated site). Analysis of phosphopeptide maps revealed that the membrane-bound RII was phosphorylated by a kinase which is unrelated to the catalytic unit (C) of kinase A. Dephosphorylation of the membrane-bound RII by an endogenous phosphatase was stimulated by both cyclic AMP and fluoride. Addition of C did not stimulate dephosphorylation even in the presence of ADP; moreover, protein inhibitor of C did not modify the effects of cyclic AMP or fluoride. The effects of both cyclic AMP and fluoride were, however, inhibited by C. Results indicate that rat liver plasma membranes contain a phosphorylation-dephosphorylation system for which RII is a relatively specific substrate. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6.

Kiss, Z; Luo, Y; Vereb, G

1986-01-01

359

Dual transcriptional regulation of the Escherichia coli phosphate-starvation-inducible psiE gene of the phosphate regulon by PhoB and the cyclic AMP (cAMP)-cAMP receptor protein complex.  

PubMed

We have shown that the Escherichia coli phosphate-starvation-inducible psiE gene is regulated by both phosphate and the carbon source by using both lacZ and chloramphenicol acetyltransferase gene (cat) fusions. Yet, under all conditions tested, a single transcriptional start site lying 7 bp downstream of a predicted -10 region was revealed by primer extension analysis. DNase I footprinting showed that the PhoB transcriptional-activator protein protects two predicted pho boxes lying upstream of and near the -35 promoter region. Similar analysis showed that the cyclic AMP (cAMP)-cAMP receptor protein (cAMP-CRP) complex binds a region that overlaps with the downstream pho box. These results, together with measurements of the in vivo psiE promoter activity under various conditions, show that expression of the psiE gene is under direct positive and negative control by PhoB and cAMP-CRP, respectively. PMID:10986267

Kim, S K; Kimura, S; Shinagawa, H; Nakata, A; Lee, K S; Wanner, B L; Makino, K

2000-10-01

360

Isoproterenol decreases LDL receptor expression in rat adipose cells: activation of cyclic AMP-dependent proteolysis  

Microsoft Academic Search

The low density lipoprotein (LDL) receptor is part of a family of proteins that mediate the uptake of lipoproteins into cells. In this paper we have demonstrated the over-ex- pression in E. coli of a rat LDL receptor fusion protein that contains the region of the receptor sharing homology with the EGF precursor. The fusion protein was utilized to immu-

Fredric B. Kraemer; Vanita Natu; Anita Singh-Bist; Shailja Patel; Michael C. Komaromy; Satyananyana Medicherla; Salman Azhar; Carole Sztalryd

361

Circadian rhythmicity in the activities of adenyiate cyciase and phosphodiesterase in synchronously dividing and stationary-phase cultures of the achiorophylious ZC mutant of Euglena gracilis  

Microsoft Academic Search

Summary Key factors in the adenosine 3',5'-cyclic monophos- phate (cyclic AMP) metabolic pathway are two enzymes responsible for its generation and degra- dation, namely, adenyiate cyciase (AC) and phospho- diesterase (PDE). In LD: 12,12 (12 h light, 12 h dark), these enzymes were found to undergo bimodal, circadian variation of activity in both dividing and nondividing cultures of the photosynthesis-deficient,

JIAN TONG; ISABELLE A. CARRE; LELAND N. EDMUNDS

1991-01-01

362

Influence of cyclic AMP, agmatine, and a novel protein encoded by a flanking gene on speB (agmatine ureohydrolase) in Escherichia coli.  

PubMed Central

The speB gene of Escherichia coli encodes agmatine ureohydrolase (AUH), a putrescine biosynthetic enzyme. The speB gene is transcribed either from its own promoter or as a polycistronic message from the promoter of the speA gene encoding arginine decarboxylase. Two open reading frames (ORF1 and ORF2) are present on the strand complementary to speB; approximately 90% of ORF2 overlaps the speB coding region. Analysis of transcriptional and translational fusions of ORF1 or ORF2 to lacZ revealed that ORF1 encoded a novel protein while ORF2 was not transcribed. Deletion of ORF1 from a plasmid containing ORF1, ORF2, and speB reduced the activity of AUH by 83%. In contrast, the presence of plasmid-encoded ORF1 caused an 86% increase in chromosomally encoded AUH activity. ORF1 did not stimulate alkaline phosphatase expressed from a phi(speB-phoA) transcriptional fusion encoded on the same plasmid. Western analysis (immunoblot) of a phi(ORF1-lacZ) translational fusion revealed that ORF1 encodes a 25.3-kDa protein. Agmatine induced transcription of phi(speB-phoA) but not phi(speA-phoA) fusions. Consequently, agmatine affects selection between the monocistronic and the polycistronic modes of speB transcription. In contrast, cyclic AMP (cAMP) repressed AUH activity of chromosomally encoded AUH but had no effect on plasmid-borne speB nor phi(speB-phoA). It is concluded that ORF1 encodes a protein which is a posttranscriptional regulator of speB, agmatine induces speB independent of speA, and cAMP regulates speB indirectly. Images

Szumanski, M B; Boyle, S M

1992-01-01

363

Synthesis of interleukin 6 (interferon-. beta. /sub 2//B cell stimulatory factor 2) in human fibroblasts is triggered by an increase in intracellular cyclic AMP  

SciTech Connect

Interleukin 6 (IL-6; also referred to as interferon-..beta../sub 2/, 26-kDa protein, and B cell stimulatory factor 2) is a cytokine whose actions include a stimulation of immunoglobulin synthesis, enhancement of B cell growth, and modulation of acute phase protein synthesis by hepatocytes. Synthesis of IL-6 is stimulated by interleukin 1 (IL-1), tumor necrosis factor (TNF), or platelet-derived growth factor. The authors examined the role of the cyclic AMP (cAMP)-dependent signal transduction pathway in IL-6 gene expression. Several activators of adenylate cyclase, including prostaglandin E1, forskolin, and cholera toxin, as well as the phosphodiesterase inhibitor isobutylmethylxanthine and the cAMP analog dibutyryl cAMP, shared the ability to cause a dramatic and sustained increase in IL-6 mRNA levels in human FS-4 fibroblasts. Actinomycin D treatment abolished this enhancement. Treatments that increased intracellular cAMP also stimulated the secretion of the IL-6 protein in a biologically active form. Increased intracellular cAMP appears to enhance IL-6 gene expression by a protein kinase C-independent mechanism because down-regulation of protein kinase C by a chronic exposure of cells to a high dose of 12-O-tetradecanoylphorbol 13-acetate did not abolish the enhancement of IL-6 expression by treatments that increase cAMP. IL-1 and TNF too increased IL-6 mRNA levels by a protein kinase C-independent mechanism. The results suggest a role for the cAMP-dependent pathway(s) in IL-6 gene activation by TNF and IL-1.

Zhange, Y.; Lin, J.X.; Vilcek, J.

1988-05-05

364

Neural expression of G protein-coupled receptors GPR3, GPR6, and GPR12 up-regulates cyclic AMP levels and promotes neurite outgrowth.  

PubMed

Cyclic AMP regulates multiple neuronal functions, including neurite outgrowth and axonal regeneration. GPR3, GPR6, and GPR12 make up a family of constitutively active G protein-coupled receptors (GPCRs) that share greater than 50% identity and 65% similarity at the amino acid level. They are highly expressed in the central nervous system, and their expression in various cell lines results in constitutive stimulation of cAMP production. When the constitutively active GPCRs were overexpressed in rat cerebellar granule neurons in culture, the transfected neurons exhibited significantly enhanced neurite outgrowth and overcame growth inhibition caused by myelin-associated glycoprotein. GPR12-mediated neurite outgrowth was the most prominent and was shown to depend on G(s) and cAMP-dependent protein kinase. Moreover, the GPR12-mediated rescue from myelin-associated glycoprotein inhibition was attributable to cAMP-dependent protein kinase-mediated inhibition of the small GTPase, RhoA. Among the three receptors, GPR3 was revealed to be enriched in the developing rat cerebellar granule neurons. When the endogenous GPR3 was knocked down, significant reduction of neurite growth was observed, which was reversed by expression of either GPR3 or GPR12. Taken together, our results indicate that expression of the constitutively active GPCRs up-regulates cAMP production in neurons, stimulates neurite outgrowth, and counteracts myelin inhibition. Further characterization of the GPCRs in developing and injured mammalian neurons should provide insights into how basal cAMP levels are regulated in neurons and could establish a firm scientific foundation for applying receptor biology to treatment of various neurological disorders. PMID:17284443

Tanaka, Shigeru; Ishii, Ken; Kasai, Kazue; Yoon, Sung Ok; Saeki, Yoshinaga

2007-02-06

365

Does cyclic 3' ,5'-adenosine monophosphate act as second messenger in a voltage-dependent response to 5-hydroxytryptamine in Aplysia?  

PubMed Central

1 The possibility that cyclic adenosine 3',5'-monophosphate (cyclic AMP) mediates a voltage-dependent inward current elicited by 5-hydroxytryptamine (5-HT) in RB and LB cells of the abdominal ganglion of Aplysia was tested. 2 Intracellular injection of cyclic AMP elicited an inward current with a similar time course, potential dependence and ionic sensitivity as the response to 5-HT. 3 Intracellular injection of guanylyl imidodiphosphate (GMP-PNP), which activated adenylate cyclase, neither mimicked nor enhanced the 5-HT-evoked current. On the contrary, it reduced the current. 4 The phosphodiesterase inhibitors, Ro20-1724, isobutyl methylxanthine (IBMX) and theophylline, each antagonized the voltage-dependent response to 5-HT. To varying degrees they each induced an inward current. 5 The adenylate cyclase antagonist, dithiobisnitrobenzoic acic (DTNB), had no effect on the response to 5-HT when applied either intracellularly or extracellularly. Intracellular injection of the phosphodiesterase activator imidazole also had no effect. 6 Tubocurarine and neostigmine did not reduce the voltage-dependent inward current evoked by 5-HT; methysergide elicited an inward current. 7 Although the observations that cyclic AMP and 5-HT can evoke similar voltage-dependent inward currents in RB and LB neurones of Aplysia might suggest a second messenger role for the cyclic nucleotide, the pharmacological data are inconsistent with this hypothesis.

Pellmar, T. C.

1981-01-01

366

Acetate Regulation of Spore Formation Is under the Control of the Ras/Cyclic AMP/Protein Kinase A Pathway and Carbon Dioxide in Saccharomyces cerevisiae  

PubMed Central

In Saccharomyces cerevisiae, the Ras/cyclic AMP (cAMP)/protein kinase A (PKA) pathway is a nutrient-sensitive signaling cascade that regulates vegetative growth, carbohydrate metabolism, and entry into meiosis. How this pathway controls later steps of meiotic development is largely unknown. Here, we have analyzed the role of the Ras/cAMP/PKA pathway in spore formation by the meiosis-specific manipulation of Ras and PKA or by the disturbance of cAMP production. We found that the regulation of spore formation by acetate takes place after commitment to meiosis and depends on PKA and appropriate A kinase activation by Ras/Cyr1 adenylyl cyclase but not by activation through the Gpa2/Gpr1 branch. We further discovered that spore formation is regulated by carbon dioxide/bicarbonate, and an analysis of mutants defective in acetate transport (ady2?) or carbonic anhydrase (nce103?) provided evidence that these metabolites are involved in connecting the nutritional state of the meiotic cell to spore number control. Finally, we observed that the potential PKA target Ady1 is required for the proper localization of the meiotic plaque proteins Mpc70 and Spo74 at spindle pole bodies and for the ability of these proteins to initiate spore formation. Overall, our investigation suggests that the Ras/cAMP/PKA pathway plays a crucial role in the regulation of spore formation by acetate and indicates that the control of meiotic development by this signaling cascade takes places at several steps and is more complex than previously anticipated.

Jungbluth, Marc; Mosch, Hans-Ulrich

2012-01-01

367

Putting on the Brakes: Cyclic AMP as a Multipronged Controller of Macrophage Function  

NSDL National Science Digital Library

Macrophages orchestrate innate immune responses in tissues by activating various proinflammatory signaling programs. A key mechanism for preventing inflammatory disease states that result from excessive activation of such programs is the generation of the second messenger cyclic adenosine monophosphate (cAMP) by ligation of certain guanine nucleotide–binding protein (G protein)–coupled receptors (GPCRs). The pleiotropic actions of this cyclic nucleotide on various inflammatory functions of macrophages are mediated by diverse molecular mechanisms, including the assembly of distinct multiprotein complexes. A better understanding of crosstalk between cAMP signaling and proinflammatory pathways in macrophages may provide a basis for improved immunomodulatory strategies.

Marc Peters-Golden (Ann Arbor;University of Michigan Medical School REV)

2009-06-16

368

Presence of free cyclic AMP receptor protein and regulation of its level by cyclic AMP in neuroblastoma-glioma hybrid cells.  

PubMed Central

Neuroblastoma-glioma hybrid cells of line 108CC-5 were found to contain high levels of soluble adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase activity and high levels of two specific cAMP receptor proteins, RI and RII. Treatment of the hybrid cells with dibutyryl cAMP increased the level of RI but did not significantly affect the level either of RII or of cAMP-dependent protein kinase activity. The effect of dibutyryl cAMP could be mimicked by prostaglandin E1 and 3-isobutyl-1-methylxanthine, both of which are known to raise cAMP levels in neuroblastoma-glioma hybrid cells. Both in control as well as in dibutyryl cAMP-treated cells, RII but not RI was associated with cAMP-dependent protein kinase. Several lines of evidence suggest that RI represents the free regulatory subunit of type I cAMP-dependent protein kinase. The presence of this regulatory subunit as free cAMP receptor protein in neuroblastoma-glioma hybrid cells may be of significance with respect to the regulation of growth and differentiation in tumor cells. Images

Walter, U; Costa, M R; Breakefield, X O; Greengard, P

1979-01-01

369

Cyclic AMP-mediated suppression of normal and neoplastic B cell proliferation is associated with regulation of myc and Ha-ras protooncogenes.  

PubMed

Cyclic AMP functions as a negative regulator of cell proliferation in a variety of cell systems. We show here that the proliferation of normal and neoplastic B cells can be inhibited by high intracellular levels of cAMP. Thus forskolin treatment of the neoplastic B precursor cell line Reh induced a rapid increase in the cAMP level, which was followed by an accumulation of cells in the G0/G1 phase of the cell cycle over a period of 2-3 days. Similar inhibition of Reh cell proliferation after 3 days was observed whether forskolin was present continuously or only during the first 5 hr. Both c-myc and c-Ha-ras protein levels were transiently down-regulated at 4 hr of forskolin treatment, suggesting that these protooncogenes play a role in the process leading to cAMP-mediated growth cessation. Northern-blot analysis showed that the steady-state levels of c-myc RNA rapidly declined in all phases of the cell cycle, to return to control levels within a time period of 24 hr. In contrast, the c-Ha-ras mRNA level was steadily maintained. Thus the expression of c-myc and c-Ha-ras protein was regulated at different metabolic levels. The reduced proliferative capacity of the B precursor cell line in the presence of forskolin was not linked to induced differentiation. This was judged from the lack of appearance of three different B cell differentiation markers; cytoplasmic immunoglobulin heavy chain and two antigens recognized by the monoclonal antibodies B1 (CD20) and HH1 (CD37). We also showed that forskolin partially inhibited the proliferation of normal B lymphocytes stimulated by anti-immunoglobulins (anti-mu) and B cell growth factor (BCGF). The burst of c-myc mRNA during activation of normal B cells was also reduced by forskolin. PMID:3036888

Blomhoff, H K; Smeland, E B; Beiske, K; Blomhoff, R; Ruud, E; Bjøro, T; Pfeifer-Ohlsson, S; Watt, R; Funderud, S; Godal, T

1987-06-01

370

Modulation of a human lymphoblastoid B cell line by cyclic AMP. Ig secretion and phosphatidylcholine metabolism  

SciTech Connect

A transformed human B cell line, LA350, was found to be sensitive to cAMP-elevating agents by responding with rapid (0 to 2 h) severalfold elevations of intracellular cAMP to treatment with cholera toxin, isobutylmethylxanthine (IBMX), forskolin, and dibutyryl cAMP (all p less than 0.001). These cAMP-elevating agents also produced significant inhibitions of subsequent (48 to 72 h) Ig secretion by the same B cells as measured by a reverse hemolytic plaque assay and an enzyme-linked immunoadsorbent assay for IgM (both p less than 0.001). PMA- and IBMX-treated cells were particularly responsive to the effects of cholera toxin, showing a doubling of cAMP content and profound decrease in Ig production (p less than 0.001). Because our previous studies had correlated activation of the metabolic turnover of the phosphatidylcholine (PC) fraction of membrane phospholipids with enhanced Ig secretion, we examined the sensitivity of PC metabolism to cAMP in control and PMA-stimulated cells. Formation of PC was found to be inhibited by forskolin and IBMX (both p less than 0.002) but breakdown of PC was stimulated (p less than 0.001). These findings imply that as the enzymatic products of PC, choline phosphate and diacylglycerol, are depleted due to the combined effects of cAMP upon synthesis and turnover of PC, there is a decrease in Ig secretion. Since diacylglycerol activates protein kinase C, it appears reasonable that Ig secretion is at least partially regulated by cAMP-responsive alterations in PC metabolism produced by protein kinase C-induced phosphorylation. We conclude that the early cAMP-sensitive changes in PC metabolism in this activated B cell line may signal for subsequent alterations in Ig secretion.

Shearer, W.T.; Patke, C.L.; Gilliam, E.B.; Rosenblatt, H.M.; Barron, K.S.; Orson, F.M.

1988-09-01

371

The action of insulin and dibutyryl cyclic AMP on the biosynthesis of polyunsaturated acids of alpha-linolenic acid family in HTC cells.  

PubMed

Incubation of HTC cells (7288 C) with 114C-alpha-linolenic acid in Swim's 77 medium during 24 hours converted the fatty acid to octadeca-6,9,12,15-tetraenoic acid, eicosa-11,14,17-trienoic acid, eicosa-8,11,14,17-tetraenoic acid, eicosa-5,11,14,17-tetraenoic acid, eicosa-5,8,11,14,17-pentaenoic acid and unsaturated acids of 22 carbons. The existence of two pathways was recognized: one initiated by a delta6-desaturation and the other by an elongation of alpha-linolenic acid. Incubation of the cells with insulin and dibutyryl cyclic AMP modified both pathways in different ways. HTC cells were sensitive to insulin which enhanced the desaturating route increasing eicosapentaenoic acid synthesis and depressed the elongating route decreasing eicosatrienoic acid. In an opposite way, dibutyryl cyclic AMP decreased eicosapentaenoic acid synthesis and increased eicosatrienoic acid. PMID:184376

de Alaniz, M J; de Gómez Dumm, I N; Brenner, R R

1976-07-30

372

Effects of Dibutyryl CyclicAMP on Survival and Neuronal Differentiation of Neural Stem\\/Progenitor Cells Transplanted into Spinal Cord Injured Rats  

Microsoft Academic Search

Neural stem\\/progenitor cells (NSPCs) have great potential as a cell replacement therapy for spinal cord injury. However, poor control over transplant cell differentiation and survival remain major obstacles. In this study, we asked whether dibutyryl cyclic-AMP (dbcAMP), which was shown to induce up to 85% in vitro differentiation of NSPCs into neurons would enhance survival of transplanted NSPCs through prolonged

Howard Kim; Tasneem Zahir; Charles H. Tator; Molly S. Shoichet; Maria A. Deli

2011-01-01

373

Inhibition of morphine tolerance and dependence by diazepam and its relation to cyclic AMP levels in discrete rat brain regions and spinal cord  

Microsoft Academic Search

Diazepam inhibits morphine tolerance and dependence and reverses a decrease in the met-enkephalin level in brain induced by morphine. In this study, we investigated whether inhibition of morphine-induced tolerance and dependence by diazepam involved a change in cyclic AMP levels in discrete rat brain regions and spinal cord. Male Sprague-Dawley rats were made tolerant and dependent by subcutaneous (s.c.) implantation

Ming-Jyh Sheu; Pongruk Sribanditmongkol; Didi N. Santosa; Gopi A. Tejwani

1995-01-01

374

Temporal relationship between nerve-stump-length-dependent changes in the autophosphorylation of a cyclic AMP-dependent protein kinase and the acetylcholine receptor content in skeletal muscle  

Microsoft Academic Search

The acetylcholine receptor (AChR) content and the autorphosphorylation of the regulatory subunit of cyclic AMP-dependent protein kinase type II (R-II) were evaluated in rat soleus muscles at 24, 30 and 66 hr after surgical denervation by cutting the nerve at a short distance (short-nerve-stump) and at a long distance (long-nerve-stump) from the muscle. AChR content was based on the specific

Scott T. Sayers; Hock C. Yeoh; Jerry A. McLane; Irene R. Held

1988-01-01

375

Effects of SQ 22536, an adenylyl cyclase inhibitor, on isoproterenol-induced cyclic AMP elevation and relaxation in newborn ovine pulmonary veins  

Microsoft Academic Search

The effects of inhibition of adenylyl cyclase on isoproterenol-induced relaxation were determined in isolated pulmonary veins of newborn lambs (7–12 days old). In veins constricted with endothelin-1, isoproterenol at concentrations ?3×10?9 M had no effect on the cyclic AMP (cAMP) content but caused up to 56% relaxation. At higher concentrations (?10?8 M), isoproterenol elevated cAMP content and caused further relaxation.

Yuansheng Gao; J Usha Raj

2002-01-01

376

Histamine augments ? 2-adrenoceptor-induced cyclic AMP accumulation in human prostate cancer cells DU145 independently of known histamine receptors  

Microsoft Academic Search

Androgen-independent prostate cancer cells DU-145 express a number of G protein-coupled receptors, including histamine H1 receptors. There is evidence for the presence of ?-adrenoceptors in the human prostate, and in this work we set out to characterise the expression of ?-adrenoceptors by DU-145 cells, their linking to cyclic AMP (cAMP) formation and the possible modulation by histamine H1 receptors of

Judith Ramos-Jiménez; Luis-Enrique Soria-Jasso; Aurelio López-Colombo; Jorge-Alberto Reyes-Esparza; Javier Camacho; José-Antonio Arias-Montaño

2007-01-01

377

Elevated cyclic AMP and PDE4 inhibition induce chemokine expression in human monocyte-derived macrophages  

PubMed Central

Macrophages are central mediators of the innate immune system that can be differentiated from monocytes upon exposure to cytokines. While increased cyclic adenosine monophosphate (cAMP) levels are known to inhibit many lipopolysaccharide-elicited macrophage inflammatory responses, the effects of elevated cAMP on monocyte/macrophage differentiation are not as well understood. We show here that during differentiation, cAMP agonists can cause a large increase in the mRNA and protein levels of several of the pro-inflammatory CXCL and CCL chemokines. The cAMP mediator-exchange protein activated by cAMP (Epac) contributes substantially to the increase in these chemokines. These chemokines are known to play an important role in the regulation of immune responses, particularly regarding the pathogenesis of asthma and chronic obstructive pulmonary disorder. We also found that a selective cAMP-degrading phosphodiesterase (PDE) 4 inhibitor can potentiate the chemokine expression elicited by low-dose forskolin or Prostaglandin E2 (PGE2). These data suggest that chemokine receptor antagonists administered in conjunction with a PDE4 inhibitor may improve both the efficacy and safety of PDE4-inhibitor therapy for chronic inflammatory disorders.

Hertz, Angie L.; Bender, Andrew T.; Smith, Kimberly C.; Gilchrist, Mark; Amieux, Paul S.; Aderem, Alan; Beavo, Joseph A.

2009-01-01

378

Novel model for "calcium paradox" in sympathetic transmission of smooth muscles: role of cyclic AMP pathway.  

PubMed

It is well established that reduction of Ca2+ influx through L-type voltage-dependent Ca2+ channel (L-type VDCC), or increase of cytosolic cAMP concentration ([cAMP]c), inhibit contractile activity of smooth muscles in response to transmitters released from sympathetic nerves. Surprisingly, in this work we observed that simultaneous administration of L-type VDCC blocker (verapamil) and [cAMP]c enhancers (rolipram, IBMX and forskolin) potentiated purinergic contractions evoked by electrical field stimulation of rat vas deferens, instead of inhibiting them. These results, including its role in sympathetic transmission, can be considered as a "calcium paradox". On the other hand, this potentiation was prevented by reduction of [cAMP]c by inhibition of adenylyl cyclase (SQ 22536) or depletion of Ca2+ storage of sarco-endoplasmic reticulum by blockade of Ca2+ reuptake (thapsigargin). In addition, cytosolic Ca2+ concentration ([Ca2+]c) evaluated by fluorescence microscopy in rat adrenal medullary slices was significantly reduced by verapamil or rolipram. In contrast, simultaneous incubation of adrenal slices with these compounds significantly increased [Ca2+]c. This effect was prevented by thapsigargin. Thus, a reduction of [Ca2+]c due to blockade of Ca2+ influx through L-type VDCC could stimulate adenylyl cyclase activity increasing [cAMP]c thereby stimulating Ca2+ release from endoplasmic reticulum, resulting in augmented transmitter release in sympathetic nerves and contraction. PMID:23849429

Bergantin, Leandro Bueno; Souza, Cláudio Fontes; Ferreira, Regiane Miranda; Smaili, Soraya Soubhi; Jurkiewicz, Neide Hyppolito; Caricati-Neto, Afonso; Jurkiewicz, Aron

2013-07-09

379

Biophysical properties and microfilament assembly in neutrophils: modulation by cyclic AMP  

PubMed Central

The microfilament lattice, composed primarily of filamentous (F)-actin, determines in large part the mechanical (deformability) properties of neutrophils, and thus may regulate the ability of neutrophils to transit a microvascular bed. Circulating factors may stimulate the neutrophil to become rigid and therefore be retained in the capillaries. We hypothesized that cell stiffening might be attenuated by an increase in intracellular cAMP. A combination of cell filtration and cell poking (mechanical indentation) was used to measure cell deformability. Neutrophils pretreated with dibutyryl cAMP (db-cAMP) or the combination of prostaglandin E2 (PGE2, a stimulator of adenylate cyclase) and isobutylmethylxanthine (IBMX, an inhibitor of phosphodiesterase) demonstrated significant inhibition of the n-formyl- methionyl-leucyl-phenylalanine (fMLP)-inducing stiffening. The inhibition of cell stiffening was associated with an increase in intracellular cAMP as measured by enzyme-linked immunoassay (EIA) and an increase in the activity of the cAMP-dependent kinase (A-kinase). Treatment with PGE2 and IBMX also resulted in a decrease in the F-actin content of stimulated neutrophils as assayed by NBD-phallacidin staining and flow cytometry or by changes in right angle light scattering. Direct addition of cAMP to electropermeabilized neutrophils resulted in attenuation of fMLP-induced actin assembly. Neutrophils stimulated with fMLP demonstrated a rapid redistribution of F-actin from a diffuse cortical location to a peripheral ring as assessed by conventional and scanning confocal fluorescence microscopy. Pretreatment of neutrophils with the combination of IBMX and PGE2 resulted in incomplete development and fragmentation of the cortical ring. We conclude that assembly and redistribution of F-actin may be responsible for cell stiffening after exposure to stimulants and that this response was attenuated by agents that increase intracellular cAMP, by altering the amount and spatial organization of the microfilament component of the cytoskeleton.

1991-01-01

380

Cyclic GMP from the surrounding somatic cells regulates cyclic AMP and meiosis in the mouse oocyte  

PubMed Central

Summary Mammalian oocytes are arrested in meiotic prophase by an inhibitory signal from the surrounding somatic cells in the ovarian follicle. In response to luteinizing hormone (LH), which binds to receptors on the somatic cells, the oocyte proceeds to second metaphase, where it can be fertilized. Here we investigate how the somatic cells regulate the prophase-to-metaphase transition in the oocyte, and show that the inhibitory signal from the somatic cells is cGMP. Using FRET-based cyclic nucleotide sensors in follicle-enclosed mouse oocytes, we find that cGMP passes through gap junctions into the oocyte, where it inhibits the hydrolysis of cAMP by the phosphodiesterase PDE3A. This inhibition maintains a high concentration of cAMP and thus blocks meiotic progression. LH reverses the inhibitory signal by lowering cGMP levels in the somatic cells (from ?2 ?M to ?80 nM at 1 hour after LH stimulation) and by closing gap junctions between the somatic cells. The resulting decrease in oocyte cGMP (from ?1 ?M to ?40 nM) relieves the inhibition of PDE3A, increasing its activity by ?5-fold. This causes a decrease in oocyte cAMP (from ?700 nM to ?140 nM), leading to the resumption of meiosis.

Norris, Rachael P.; Ratzan, William J.; Freudzon, Marina; Mehlmann, Lisa M.; Krall, Judith; Movsesian, Matthew A.; Wang, Huanchen; Ke, Hengming; Nikolaev, Viacheslav O.; Jaffe, Laurinda A.

2009-01-01