Sample records for activates cyclic-amp response

  1. Cyclic AMP-dependent protein kinase and Epac mediate cyclic AMP responses in pancreatic acini

    PubMed Central

    Chaudhuri, Anamika; Husain, Sohail Z.; Kolodecik, Thomas R.; Grant, Wayne M.; Gorelick, Fred S.

    2010-01-01

    The pancreatic acinar cell has several phenotypic responses to cAMP agonists. At physiological concentrations of the muscarinic agonist carbachol (1 ?M) or the CCK analog caerulein (100 pM), ligands that increase cytosolic Ca2+, cAMP acts synergistically to enhance secretion. Supraphysiological concentrations of carbachol (1 mM) or caerulein (100 nM) suppress secretion and cause intracellular zymogen activation; cAMP enhances both zymogen activation and reverses the suppression of secretion. In addition to stimulating cAMP-dependent protein kinase (PKA), recent studies using cAMP analogs that lack a PKA response have shown that cAMP can also act through the cAMP-binding protein, Epac (exchange protein directly activated by cyclic AMP). The roles of PKA and Epac in cAMP responses were examined in isolated pancreatic acini. The activation of both cAMP-dependent pathways or the selective activation of Epac was found to enhance amylase secretion induced by physiological and supraphysiological concentrations of the muscarinic agonist carbachol. Similarly, activation of both PKA or the specific activation of Epac enhanced carbachol-induced activation of trypsinogen and chymotrypsinogen. Disorganization of the apical actin cytoskeleton has been linked to the decreased secretion observed with supraphysiological concentrations of carbachol and caerulein. Although stimulation of PKA and Epac or Epac alone could largely overcome the decreased secretion observed with either supraphysiological carbachol or caerulein, stimulation of cAMP pathways did not reduce the disorganization of the apical cytoskeleton. These studies demonstrate that PKA and Epac pathways are coupled to both secretion and zymogen activation in the pancreatic acinar cell. PMID:17234888

  2. The Interplay between Cyclic AMP, MAPK, and NF-?B Pathways in Response to Proinflammatory Signals in Microglia

    PubMed Central

    Ghosh, Mousumi; Aguirre, Vladimir; Wai, Khine; Felfly, Hady; Dietrich, W. Dalton; Pearse, Damien D.

    2015-01-01

    Cyclic AMP is an important intracellular regulator of microglial cell homeostasis and its negative perturbation through proinflammatory signaling results in microglial cell activation. Though cytokines, TNF-? and IL-1?, decrease intracellular cyclic AMP, the mechanism by which this occurs is poorly understood. The current study examined which signaling pathways are responsible for decreasing cyclic AMP in microglia following TNF-? stimulation and sought to identify the role cyclic AMP plays in regulating these pathways. In EOC2 microglia, TNF-? produced a dramatic reduction in cyclic AMP and increased cyclic AMP-dependent PDE activity that could be antagonized by Rolipram, myristoylated-PKI, PD98059, or JSH-23, implicating a role for PDE4, PKA, MEK, and NF-?B in this regulation. Following TNF-? there were significant increases in iNOS and COX-2 immunoreactivity, phosphorylated ERK1/2 and NF-?B-p65, I?B degradation, and NF-?B p65 nuclear translocation, which were reduced in the presence of high levels of cyclic AMP, indicating that reductions in cyclic AMP during cytokine stimulation are important for removing its inhibitory action on NF-?B activation and subsequent proinflammatory gene expression. Further elucidation of the signaling crosstalk involved in decreasing cyclic AMP in response to inflammatory signals may provide novel therapeutic targets for modulating microglial cell activation during neurological injury and disease. PMID:25722974

  3. Novel interactions between human T-cell leukemia virus type I Tax and activating transcription factor 3 at a cyclic AMP-responsive element.

    PubMed Central

    Low, K G; Chu, H M; Schwartz, P M; Daniels, G M; Melner, M H; Comb, M J

    1994-01-01

    Human proenkephalin gene transcription is transactivated by human T-cell leukemia virus type I (HTLV-I) Tax in human Jurkat T lymphocytes. This transactivation was further enhanced in Jurkat cells treated with concanavalin A, cyclic AMP, or 12-O-tetradecanoylphorbol-13-acetate. Deletion and cis-element transfer analyses of the human proenkephalin promoter identified a cyclic AMP-responsive AP-1 element (-92 to -86) as both necessary and sufficient to confer Tax-dependent transactivation. Different AP-1 or cyclic AMP-responsive element-binding protein (CREB)/activating transcription factor (ATF) proteins which bind this element were expressed in murine teratocarcinoma F9 cells to identify those capable of mediating Tax-dependent transactivation of human proenkephalin gene transcription. Although CREB, c-Fos, c-Jun, and JunD did not have significant effects, JunB inhibited the Tax-dependent transactivation. In contrast, ATF3 dramatically induced Tax-dependent transactivation, which was further enhanced by protein kinase A. Electrophoretic mobility shift assays with recombinant fusion proteins expressed and purified from bacteria indicate that the DNA-binding activity of ATF3 is also dramatically enhanced by Tax. Chimeric fusion proteins consisting of the DNA-binding domain of the yeast transcription factor Gal4 and the amino-terminal domain (residues 1 to 66) of ATF3 were able to mediate Tax-dependent transactivation of a Gal4-responsive promoter, which suggests a direct involvement of this region of ATF3. Recombinant fusion proteins of glutathione S-transferase with either the amino- or carboxy-terminal (residues 139 to 181) domain of ATF3 were able to specifically interact with Tax. Furthermore, specific antisera directed against Tax coimmunoprecipitated ATF3 only in the presence of Tax. Images PMID:8007991

  4. Mutants of PC12 cells with altered cyclic AMP responses

    SciTech Connect

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

    1984-10-01

    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.

  5. Temporal effect of adrenocorticotrophic hormone on adrenal glucocorticoid steroidogenesis: involvement of the transducer of regulated cyclic AMP-response element-binding protein activity.

    PubMed

    Spiga, F; Liu, Y; Aguilera, G; Lightman, S L

    2011-02-01

    The availability of active steroidogenic acute regulatory protein (StAR) and side-chain cleavage cytochrome P450 (P450scc) are rate-limiting steps for steroidogenesis. Transcription of StAR and P450scc genes depends on cyclic AMP-response element-binding protein (CREB) phosphorylation and CREB co-activator, transducer of regulated CREB activity (TORC), which is regulated by salt-inducible kinase 1 (SIK1). In the present study, we investigated the relationship between TORC activation and adrenocorticotrophic hormone (ACTH)-induced steroidogenesis in vivo, by examining the time-course of the effect of ACTH injection (4?ng, i.v.) on the transcriptional activity of StAR and P450scc genes and the nuclear accumulation of transducer of regulated CREB activity 2 (TORC2) in rat adrenal cortex. ACTH produced rapid and transient increases in plasma corticosterone, with maximal responses between 5 and 15?min, and a decrease to almost basal values at 30?min. StAR and P450scc hnRNA levels increased 15?min following ACTH and decreased toward basal values at 30?min. Concomitant with an increase in nuclear phospho-CREB, ACTH injection induced nuclear accumulation of TORC2, with maximal levels at 5?min and a return to basal values by 30?min. The decline of nuclear TORC2 was paralleled by increases in SIK1 hnRNA and mRNA 15 and 30?min after injection, respectively. The early rises in plasma corticosterone preceding StAR and P450scc gene transcription suggest that post-transcriptional and post-translational changes in StAR protein mediate the early steroidogenic responses. Furthermore, the direct temporal relationship between nuclear accumulation of TORC2 and the increase in transcription of steroidogenic proteins, implicates TORC2 in the physiological regulation of steroidogenesis in the adrenal cortex. The delayed induction of SIK1 suggests a role for SIK1 in the declining phase of steroidogenesis. PMID:21083631

  6. Repeated predictable or unpredictable stress: effects on cocaine-induced locomotion and cyclic AMP-dependent protein kinase activity.

    PubMed

    Araujo, Ana Paula N; DeLucia, Roberto; Scavone, Cristoforo; Planeta, Cleopatra S

    2003-02-17

    Stressful experiences appear to have a strong influence on susceptibility to drug taking behavior. Cross-sensitization between stress and drug-induced locomotor response has been found. Locomotor response to novelty or cocaine (10 mg/kg, i.p.), cyclic AMP-dependent protein kinase (PKA) activity in the nucleus accumbens and basal corticosterone levels were evaluated in male adult rats exposed to acute and chronic predictable or unpredictable stress. Rats exposed to a 14-day predictable stress showed increased locomotor response to novelty and to cocaine, whereas rats exposed to chronic unpredictable stress demonstrated increased cyclic AMP-dependent PKA activity in the nucleus accumbens. Both predictable and unpredictable stress increased basal corticosterone plasma levels. These experiments demonstrated that stress-induced early cocaine sensitization depends on the stress regime and is apparently dissociated from stress-induced changes in cyclic AMP-dependent PKA activity and corticosterone levels. PMID:12642178

  7. Activation of Cannabinoid Receptor Type 1 (Cb1r) Disrupts Hepatic Insulin Receptor Signaling via Cyclic AMP-response Element-binding Protein H (Crebh)-mediated Induction of Lipin1 Gene*

    PubMed Central

    Chanda, Dipanjan; Kim, Yong-Hoon; Kim, Don-Kyu; Lee, Min-Woo; Lee, Su-Yeon; Park, Tae-Sik; Koo, Seung-Hoi; Lee, Chul-Ho; Choi, Hueng-Sik

    2012-01-01

    Activation of hepatic cannabinoid 1 receptor (Cb1r) signaling has been implicated in the development of phenotypes associated with fatty liver, hypertriglyceridemia, and insulin resistance. In the current study, we have elucidated the critical role of endoplasmic reticulum-bound transcription factor cyclic AMP-response element-binding protein H (Crebh) in mediating activated Cb1r signaling in inducing phosphatidic acid phosphatase Lipin1 gene expression and subsequently deregulating hepatic insulin receptor signaling. Cb1r agonist (2-arachidonoylglycerol (2-AG)) treatment induced Lipin1 gene expression in a Crebh-dependent manner via recruiting CREBH to the endogenous Lipin1 gene promoter. Adenoviral overexpression of Crebh or 2-AG treatment in mice induced Lipin1 gene expression to increase the hepatic diacylglycerol (DAG) level and phosphorylation of protein kinase C? (PKC?). This in turn inhibited hepatic insulin receptor signaling. Knockdown of Crebh or Cb1r antagonism attenuated 2-AG-mediated induction of Lipin1 gene expression and decreased DAG production in mouse liver and subsequently restored insulin receptor signaling. Similarly, knockdown of Lipin1 attenuated the 2-AG-induced increase in the DAG level and PKC? phosphorylation. Finally, shRNA-mediated knockdown of Crebh partially but significantly blunted Lipin1 expression and the DAG level in db/db mice. These results demonstrate a novel mechanism by which Cb1r signaling induces Lipin1 gene expression and increases DAG production by activating Crebh, thereby deregulating insulin receptor signaling pathway and lipid homeostasis. PMID:22989885

  8. Modulation of calcium-activated non-specific cation currents by cyclic AMP-dependent phosphorylation in neurones of Helix.

    PubMed Central

    Partridge, L D; Swandulla, D; Müller, T H

    1990-01-01

    1. Currents through calcium-activated non-specific cation (CAN) channels were studied in the fast burster neurone of Helix aspersa and Helix pomatia. CAN currents were activated by reproducible intracellular injections of small quantities of Ca2+ utilizing a fast, quantitative pressure injection technique. 2. External application of forskolin (10-25 microM), an activator of adenylate cyclase, caused the endogenous bursting activity of the cells to be replaced by beating activity. These same concentrations of forskolin reduced CAN currents reversibly to about 50%. 3. External application of IBMX (3-isobutyl-1-methylxanthine, 100 microM), an inhibitor of phosphodiesterase, the enzyme which breaks down cyclic AMP, reduced CAN currents reversibly to about 40%. 4. External application of the membrane-permeable cyclic AMP analogues 8-bromo-cyclic AMP and dibutyryl-cyclic AMP (100 microM) caused almost complete block of the CAN current. A marked reduction in the CAN current was also observed following quantitative injections of cyclic AMP (internal concentrations up to 50 microM) directly into the cells from a second pressure injection pipette. 5. Similar results were obtained with quantitative injections of the catalytic subunit (C-subunit) of the cyclic AMP-dependent protein kinase (internal concentrations 10(-4) units of enzyme) directly into the cells from a second pressure injection pipette. 6. Injection of the non-hydrolysable GTP analogue, GTP-gamma-S (internal concentrations 100 microM), which stimulates G-proteins, produced a prolonged increase in CAN current amplitude by as much as 300%. 7. External application of serotonin (100-200 microM) caused a transition from bursting to beating activity of the neurones and mimicked cyclic AMP's effects on CAN currents. Two other neurotransmitters, dopamine and acetylcholine, were not significantly effective in reducing CAN currents. 8. Injection of a peptide inhibitor of cyclic AMP-dependent protein kinase suppressed serotonin's action on bursting and on CAN current. 9. Our results indicate that CAN currents in Helix burster neurones are modulated by cyclic AMP-dependent membrane phosphorylation. They suggest that the physiological transmitter that induces this second messenger action is serotonin. The dual control of CAN channels by two second messengers, namely Ca2+ and cyclic AMP, has important functional implications. While Ca2+ activates these channels which generate the pacemaker current in these neurones, cyclic AMP-dependent phosphorylation down-regulates them, thereby resulting in modulation of neuronal bursting activity. PMID:1703569

  9. 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

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

    2008-01-01

    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…

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

    PubMed

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

    2012-04-01

    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

  11. (-)Epicatechin stimulates ERK-dependent cyclic AMP response element activity and up-regulates GluR2 in cortical neurons.

    PubMed

    Schroeter, Hagen; Bahia, Parmvir; Spencer, Jeremy P E; Sheppard, Olivia; Rattray, Marcus; Cadenas, Enrique; Rice-Evans, Catherine; Williams, Robert J

    2007-06-01

    Emerging evidence suggests that the cellular actions of flavonoids relate not simply to their antioxidant potential but also to the modulation of protein kinase signalling pathways. We investigated in primary cortical neurons, the ability of the flavan-3-ol, (-)epicatechin, and its human metabolites at physiologically relevant concentrations, to stimulate phosphorylation of the transcription factor cAMP-response element binding protein (CREB), a regulator of neuronal viability and synaptic plasticity. (-)Epicatechin at 100-300 nmol/L stimulated a rapid, extracellular signal-regulated kinase (ERK)- and PI3K-dependent, increase in CREB phosphorylation. At micromolar concentrations, stimulation was no longer apparent and at the highest concentration tested (30 mumol/L) (-)epicatechin was inhibitory. (-)Epicatechin also stimulated ERK and Akt phosphorylation with similar bell-shaped concentration-response characteristics. The human metabolite 3'-O-methyl-(-)epicatechin was as effective as (-)epicatechin at stimulating ERK phosphorylation, but (-)epicatechin glucuronide was inactive. (-)Epicatechin and 3'-O-methyl-(-)epicatechin treatments (100 nmol/L) increased CRE-luciferase activity in cortical neurons in a partially ERK-dependent manner, suggesting the potential to increase CREB-mediated gene expression. mRNA levels of the glutamate receptor subunit GluR2 increased by 60%, measured 18 h after a 15 min exposure to (-)epicatechin and this translated into an increase in GluR2 protein. Thus, (-)epicatechin has the potential to increase CREB-regulated gene expression and increase GluR2 levels and thus modulate neurotransmission, plasticity and synaptogenesis. PMID:17298385

  12. Cyclic AMP Receptor Protein: Role in Transcription Activation

    Microsoft Academic Search

    Benoit de Crombrugghe; Stephen Busby; Henri Buc

    1984-01-01

    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.

  13. Phorbol esters modulate cyclic AMP accumulation in porcine thyroid cells

    SciTech Connect

    Emoto, T.; Kasai, K.; Hiraiwa, M.; Shimoda, S.

    1988-01-01

    In cultured porcine thyroid cells, during 60 min incubation phorbol 12-myristate 13-acetate (PMA) had no effect on basal cyclic AMP accumulation and slightly stimulated cyclic AMP accumulation evoked by thyroid stimulating hormone (TSH) or forskolin. Cholera toxin-induced cyclic AMP accumulation was significantly stimulated by PMA. On the other hand, cyclic AMP accumulation evoked by prostaglandin E/sub 1/ or E/sub 2/ (PGE/sub 1/ and PGE/sub 2/) was markedly depressed by simultaneous addition of PMA. These opposing effects of PMA on cyclic AMP accumulation evoked by PGE and cholera toxin were observed in a dose-related fashion, with half-maximal effect of around 10/sup -9/ M in either case. The almost same effects of PMA on cyclic AMP accumulation in basal and stimulated conditions were also observed in freshly prepared thyroid cells. The present study was performed in the presence of phosphodiesterase inhibitor, 3-iso-butyl-1-methylxanthine (IBMX), indicating that PMA affected adenylate cyclase activity. Therefore, it is suggested that PMA may modulate the production of cyclic AMP in response to different stimuli, possibly by affecting several sites in the adenylate cyclase complex in thyroid cells.

  14. Microgravity changes in heart structure and cyclic-AMP metabolism

    NASA Technical Reports Server (NTRS)

    Philpott, D. E.; Fine, A.; Kato, K.; Egnor, R.; Cheng, L.

    1985-01-01

    The effects of microgravity on cardiac ultrastructure and cyclic AMP metabolism in tissues of rats flown on Spacelab 3 are reported. Light and electron microscope studies of cell structure, measurements of low and high Km phosphodiesterase activity, cyclic AMP-dependent protein kinase activity, and regulatory subunit compartmentation show significant deviations in flight animals when compared to ground controls. The results indicate that some changes have occurred in cellular responses associated with catecholamine receptor interactions and intracellular signal processing.

  15. Disulfiram inhibits activating transcription factor/cyclic AMP-responsive element binding protein and human melanoma growth in a metal-dependent manner in vitro, in mice and in a patient with metastatic disease.

    PubMed

    Brar, Sukhdev S; Grigg, Claude; Wilson, Kimberly S; Holder, Walter D; Dreau, Didier; Austin, Catherine; Foster, Mareva; Ghio, Andrew J; Whorton, A Richard; Stowell, Grayson W; Whittall, Linda B; Whittle, Robert R; White, David P; Kennedy, Thomas P

    2004-09-01

    The thiocarbamate alcoholism drug disulfiram blocks the P-glycoprotein extrusion pump, inhibits the transcription factor nuclear factor-kappaB, sensitizes tumors to chemotherapy, reduces angiogenesis, and inhibits tumor growth in mice. Thiocarbamates react with critical thiols and also complex metal ions. Using melanoma as the paradigm, we tested whether disulfiram might inhibit growth by forming mixed disulfides with critical thiols in a mechanism facilitated by metal ions. Disulfiram given to melanoma cells in combination with Cu2+ or Zn2+ decreased expression of cyclin A and reduced proliferation in vitro at lower concentrations than disulfiram alone. In electrophoretic mobility shift assays, disulfiram decreased transcription factor binding to the cyclic AMP-responsive element in a manner potentiated by Cu2+ ions and by the presence of glutathione, suggesting that thiocarbamates might disrupt transcription factor binding by inducing S-glutathionylation of the transcription factor DNA binding region. Disulfiram inhibited growth and angiogenesis in melanomas transplanted in severe combined immunodeficient mice, and these effects were potentiated by Zn2+ supplementation. The combination of oral zinc gluconate and disulfiram at currently approved doses for alcoholism also induced >50% reduction in hepatic metastases and produced clinical remission in a patient with stage IV metastatic ocular melanoma, who has continued on oral zinc gluconate and disulfiram therapy for 53 continuous months with negligible side effects. These findings present a novel strategy for treating metastatic melanoma by employing an old drug toward a new therapeutic use. PMID:15367699

  16. Mutations that alter the ability of the Escherichia coli cyclic AMP receptor protein to activate transcription.

    PubMed Central

    Bell, A; Gaston, K; Williams, R; Chapman, K; Kolb, A; Buc, H; Minchin, S; Williams, J; Busby, S

    1990-01-01

    The effects of a number of mutations in the E. coli cyclic AMP receptor protein (CRP) have been determined by monitoring the in vivo expression and in vitro open complex formation at two semi-synthetic promoters that are totally CRP-dependent. At one promoter the CRP-binding site is centered around 41.5 base pairs upstream from the transcription start whilst at the other promoter it is 61.5 base pairs upstream. The CRP mutation E171K reduces expression from both promoters whilst H159L renders CRP totally inactive: neither mutation stops CRP binding at either promoter. The mutations K52N and K52Q reverse the effect of H159L and 'reeducate' CRP to activate transcription. CRP carrying both H159L and K52N activates transcription from the promoter with the CRP site at -41.5 better than wild type CRP. In sharp contrast, this doubly changed CRP is totally inactive with respect to the activation of transcription from the promoter carrying the CRP site at -61.5. Our results suggest that CRP can use different contacts and/or conformations during transcription activation at promoters with different architectures. Images PMID:2259621

  17. Localized cyclic AMP-dependent protein kinase activity is required for myogenic cell fusion

    SciTech Connect

    Mukai, Atsushi [Department of Regenerative Medicine, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, 36-3 Gengo, Morioka, Oobu, Aichi 474-8522 (Japan); Hashimoto, Naohiro [Department of Regenerative Medicine, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, 36-3 Gengo, Morioka, Oobu, Aichi 474-8522 (Japan)], E-mail: nao@nils.go.jp

    2008-01-15

    Multinucleated myotubes are formed by fusion of mononucleated myogenic progenitor cells (myoblasts) during terminal skeletal muscle differentiation. In addition, myoblasts fuse with myotubes, but terminally differentiated myotubes have not been shown to fuse with each other. We show here that an adenylate cyclase activator, forskolin, and other reagents that elevate intracellular cyclic AMP (cAMP) levels induced cell fusion between small bipolar myotubes in vitro. Then an extra-large myotube, designated a 'myosheet,' was produced by both primary and established mouse myogenic cells. Myotube-to-myotube fusion always occurred between the leading edge of lamellipodia at the polar end of one myotube and the lateral plasma membrane of the other. Forskolin enhanced the formation of lamellipodia where cAMP-dependent protein kinase (PKA) was accumulated. Blocking enzymatic activity or anchoring of PKA suppressed forskolin-enhanced lamellipodium formation and prevented fusion of multinucleated myotubes. Localized PKA activity was also required for fusion of mononucleated myoblasts. The present results suggest that localized PKA plays a pivotal role in the early steps of myogenic cell fusion, such as cell-to-cell contact/recognition through lamellipodium formation. Furthermore, the localized cAMP-PKA pathway might be involved in the specification of the fusion-competent areas of the plasma membrane in lamellipodia of myogenic cells.

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

    SciTech Connect

    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

    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.

  19. Cholesterol ester hydrolase in pig liver is activated by cyclic AMP-dependent protein kinase

    SciTech Connect

    Chen, J.J.S.; Dubin, E.; Margolis, S.

    1986-05-01

    To examine whether hepatic neutral cholesterol ester hydrolase (CEH) is regulated by phosphorylation, the authors have assayed CEH activity from pig liver cytosol by measuring /sup 14/C-oleate release from labeled cholesteryl oleate at pH 7.4. When pig liver cytosol was incubated with 2 mM Mg and 0.5 mM ATP, CEH activity was increased (141 +/- 8% of control, mean +/- SEM). Addition of 25..mu..M cyclic AMP (cAMP) further activated CEH activity (164 +/- 4% of control) as compared to incubation with Mg and ATP (p < 0.02). In the presence of 5 mM EDTA or in the absence of either Mg or ATP, no activation of CEH was observed. The activation was completely abolished by further incubation of activated cytosol with E. coli alkaline phosphatase. Activation of CEH activity was partially prevented by the addition of protein kinase inhibitor (p < 0.02) and this effect was completely reversed in the presence of exogenous cAMP-dependent protein kinase (p < 0.05). To examine further the role of the cAMP-dependent protein kinase, CEH activity was purified 240-fold by 35% (NH/sub 4/)/sub 2/SO/sub 4/ precipitation and Sepharose 4B chromatography. Incubation of partially purified CEH fractions with Mg, ATP and cAMP did not increase CEH activity. Addition of exogenous cAMP-dependent protein kinase activated CEH activity of partially purified fractions. The authors observations indicate that pig liver CEH is activated by phosphorylation mediated by cAMP-dependent protein kinase.

  20. Repression of protein kinase C and stimulation of cyclic AMP response elements by fumonisin, a fungal encoded toxin which is a carcinogen.

    PubMed

    Huang, C; Dickman, M; Henderson, G; Jones, C

    1995-04-15

    Fusarium moniliforme (FM) is a major fungal pathogen of corn and is involved with stalk rot disease. FM is widely spread throughout the world, including the United States. Most strains of FM produce several mycotoxins, the most prominent of which is called fumonisin. Recent epidemiological studies indicated that ingestion of fumonisin correlates with a higher incidence of esophageal cancer in Southern and Northern Africa and China. Furthermore, fumonisin causes a neurodegenerative disease in horses, induces hepatic cancer in rats, and induces pulmonary edema in swine. Considering that high levels of fumonisin have been detected in healthy and diseased corn grown in the United States, fumonisin may pose a health threat to humans and livestock animals. Structurally, fumonisin resembles sphingolipids which are present in the membranes of animal and plant cells. At the present time, very little is known concerning the mechanism by which fumonisin elicits its carcinogenic effect. Our studies indicate that fumonisin represses expression of protein kinase C and AP-1-dependent transcription. In contrast, fumonisin stimulated a simple promoter containing a single cyclic AMP response element. Since fumonisin did not alter protein kinase A activity, it appears that cyclic AMP response element activation was independent of protein kinase A. It is hypothesized that the ability of fumonisin to alter signal transduction pathways plays a role in carcinogenesis. PMID:7712470

  1. Identification of a silencer module which selectively represses cyclic AMP-responsive element-dependent gene expression.

    PubMed Central

    Chung, K C; Huang, D; Chen, Y; Short, S; Short, M L; Zhang, Z; Jungmann, R A

    1995-01-01

    The cyclic AMP (cAMP)-inducible promoter from the rat lactate dehydrogenase A subunit gene (LDH A) is associated with a distal negative regulatory element (LDH-NRE) that represses inherent basal and cAMP-inducible promoter activity. The element is of dyad symmetry, consisting of a palindromic sequence with two half-sites, 5'-TCTTG-3'. It represses the expression of an LDH A/chloramphenicol acetyltransferase (CAT) reporter gene in a dose-dependent, orientation- and position-independent fashion, suggesting that it is a true silencer element. Uniquely, it selectively represses cAMP-responsive element (CRE)-dependent transcription but has no effect on promoters lacking a CRE sequence. The repressing action of LDH-NRE could be overcome by cotransfection with LDH A/CAT vector oligonucleotides containing either the LDH-NRE or CRE sequence. This suggests that the reversal of repression was caused by the removal of functional active, limiting transacting factors which associate with LDH-NRE as well as with CRE. Gel mobility shift, footprinting, and Southwestern blotting assays demonstrated the presence of a 69-kDa protein with specific binding activity for LDH-NRE. Additionally, gel supershift assays with anti-CREB and anti-Fos antibodies indicate the presence of CREB and Fos or antigenically closely related proteins with the LDH-NRE/protein complex. We suggest that the LDH-NRE and CRE modules functionally interact to achieve negative modulation of cAMP-responsive LDH A transcriptional activity. PMID:7565766

  2. Increases in the phosphorylation of cyclic AMP response element binding protein (CREB) and decreases in the content of calcineurin accompany thermal hyperalgesia following chronic constriction injury in rats

    Microsoft Academic Search

    Gordana Miletic; Matthew T. Pankratz; Vjekoslav Miletic

    2002-01-01

    Plasticity in the spinal dorsal horn may underlie the development of chronic pain following peripheral nerve injury or inflammation. In this study, we examined whether chronic constriction injury of the sciatic nerve was associated with changes in the immunoreactive content of cyclic AMP response element binding protein (CREB), protein kinase A (PKA), and calcineurin A? and A? in the spinal

  3. A cDNA for a human cyclic AMP response element-binding protein which is distinct from CREB and expressed preferentially in brain.

    PubMed Central

    Kara, C J; Liou, H C; Ivashkiv, L B; Glimcher, L H

    1990-01-01

    The cyclic AMP response element (CRE) is found in many cellular genes regulated by cyclic AMP, and similar elements are present in the early genes of adenovirus that are activated by E1A. The transcription factor CREB has previously been shown to bind this site, and cDNAs for CREB have recently been characterized. We report here the isolation of a cDNA encoding a human DNA-binding protein that also recognizes this motif in cellular and viral promoters. This protein, HB16, displays structural similarity to CREB and to c-Jun and c-Fos, which bind the related 12-O-tetradecanoylphorbol-13-acetate response element (TRE). HB16 contains a highly basic, putative DNA-binding domain and a leucine zipper structure thought to be involved in dimerization. Deletional analysis of HB16 demonstrated that the leucine zipper is required for its interaction with DNA. In addition, HB16 could form a complex with c-Jun but not with c-Fos. Despite its structural similarity to c-Jun and c-Fos and its interaction with c-Jun, HB16 had approximately a 10-fold-lower affinity for the TRE sequence than for the CRE sequence. Although HB16 and CREB both recognized the CRE motif, an extensive binding analysis of HB16 revealed differences in the fine specificity of binding of the two proteins. HB16 mRNA was found at various levels in many human tissues but was most abundant in brain, where its expression was widespread. The existence of more than one CRE-binding protein suggests that the CRE motif could serve multiple regulatory functions. Images PMID:2320002

  4. Role of receptor desensitization, phosphatase induction and intracellular cyclic AMP in the termination of mitogen-activated protein kinase activity in UTP-stimulated EAhy 926 endothelial cells.

    PubMed Central

    Graham, A; McLees, A; Malarkey, K; Gould, G W; Plevin, R

    1996-01-01

    We have investigated the mechanisms that bring about the termination of mitogen-activated protein kinase (MAP kinase) activation in response to UTP in EAhy 926 endothelial cells. UTP-stimulated MAP kinase activity was transient, returning to basal values by 60 min. At this time MAP kinase activation was desensitized; re-application of UTP did not further activate MAP kinase, full re-activation of MAP kinase being only apparent after a 1-2 h wash period. However, activation of MAP kinase by UTP could be sustained beyond 60 min by preincubation of the cells with the protein synthesis inhibitor cycloheximide. UTP also stimulated expression of MAP kinase phosphatase-1 and this was abolished after pretreatment with cycloheximide. Pretreatment of cells with forskolin abolished the initial activation of MAP kinase kinase or c-Raf-1 by UTP, but only affected MAP kinase activity during prolonged stimulation. The effect of forskolin on prolonged MAP kinase activation was also prevented by cycloheximide. These results suggest that the termination of MAP kinase activity in response to UTP involves a number of interacting mechanisms including receptor desensitization and the induction of a phosphatase. However, several pieces of evidence do not support a major role for MAP kinase phosphatase-1 in termination of the MAP kinase signal. Raising intracellular cyclic AMP may also be involved but only after an initial protein-synthesis step and by a mechanism that does not involve the inactivation of c-Raf-1 or MAP kinase kinase. PMID:8615830

  5. Synergistic activation of insect cAMP-dependent protein kinase A (type II) by cyclicAMP and cyclicGMP

    E-print Network

    Menzel, Randolf - Institut für Biologie

    as proposed in recent in vivo studies in honeybees [16­18]. 2. Materials and methods 2.1. Materials ApisSynergistic activation of insect cAMP-dependent protein kinase A (type II) by cyclicAMP and cyclic PKAII under physiological conditions. We tested this idea using PKAII holoenzyme purified from

  6. Cyclic AMP in prokaryotes.

    PubMed Central

    Botsford, J L; Harman, J G

    1992-01-01

    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. PMID:1315922

  7. The additional N-glycosylation site of the equine LH/CG receptor is not responsible for the limited cyclic AMP pathway activation by equine chorionic gonadotropin relative to luteinizing hormone.

    PubMed

    Saint-Dizier, Marie; Foulon-Gauze, Florence; Lecompte, François; Combarnous, Yves; Chopineau, Maryse

    2011-07-01

    In order to investigate the role of the unique seventh N23-glycosylation site of the equine LH/CG receptor (eLHCGR) in the cAMP pathway activation, COS-7 cells were transiently transfected with either the wild-type or the mutant eLHCGR(N23Q) cDNA and challenged with porcine LH and eCG for cAMP production. We showed that the N23-glycosylation site of the eLHCGR is not required for the functional coupling of the receptor with the cAMP pathway and is not responsible for the limited potency of eCG relative to pLH to activate this receptor. PMID:21804636

  8. Interdependence of Activation at rhaSR by Cyclic AMP Receptor Protein, the RNA Polymerase Alpha Subunit C-Terminal Domain, and RhaR

    Microsoft Academic Search

    CAROLYN C. HOLCROFT; SUSAN M. EGAN

    2000-01-01

    The Escherichia coli rhaSR operon encodes two AraC family transcription activators, RhaS and RhaR, and is activated by RhaR in the presence of L-rhamnose. b-Galactosidase assays of various rhaS-lacZ promoter fusions combined with mobility shift assays indicated that a cyclic AMP receptor protein (CRP) site located at 2111.5 is also required for full activation of rhaSR expression. To address the

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

    PubMed

    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

    1997-03-01

    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. PMID:9032251

  10. 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

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

    1994-01-01

    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. PMID:7969163

  11. Exchange Protein Activated by Cyclic AMP (Epac)-Mediated Induction of Suppressor of Cytokine Signaling 3 (SOCS-3) in Vascular Endothelial Cells

    Microsoft Academic Search

    William A. Sands; Hayley D. Woolson; Gillian R. Milne; Claire Rutherford; Timothy M. Palmer

    2006-01-01

    Here, we demonstrate that elevation of intracellular cyclic AMP (cAMP) in vascular endothelial cells (ECs) by either a direct activator of adenylyl cyclase or endogenous cAMP-mobilizing G protein-coupled receptors inhibited the tyrosine phosphorylation of STAT proteins by an interleukin 6 (IL-6) receptor trans-signaling complex (soluble IL-6R\\/IL-6). This was associated with the induction of suppressor of cytokine signaling 3 (SOCS-3), a

  12. Extracellular signal-regulated kinase 5 and cyclic AMP response element binding protein are novel pathways inhibited by vandetanib (ZD6474) and doxorubicin in mesotheliomas.

    PubMed

    Sayan, Mutlay; Shukla, Arti; MacPherson, Maximilian B; Macura, Sherrill L; Hillegass, Jedd M; Perkins, Timothy N; Thompson, Joyce K; Beuschel, Stacie L; Miller, Jill M; Mossman, Brooke T

    2014-11-01

    Malignant mesothelioma (MM), lung cancers, and asbestosis are hyperproliferative diseases associated with exposures to asbestos. All have a poor prognosis; thus, the need to develop novel and effective therapies is urgent. Vandetanib (Van) (ZD6474, ZACTIMA) is a tyrosine kinase inhibitor that has shown equivocal results in clinical trials for advanced non-small cell lung cancer. However, tyrosine kinase inhibitors alone have shown no significant clinical activity in phase II trials of patients with unresectable MM. Using epithelioid (HMESO) and sarcomatoid (H2373) human MM lines, the efficacy of tumor cell killing and signaling pathways modulated by Van with and without doxorubicin (Dox) was examined. Van alone reduced total cell numbers in HMESO MM and synergistically increased the toxicity of Dox in HMESO and H2373 cells. Most importantly, we identified two novel cell survival/resistance pathways, ERK5 and cyclic AMP response element binding protein (CREB), that were inhibited by Van and Dox. After silencing of either ERK5 or CREB, significant decreases in cell numbers in the Dox-resistant sarcomatoid H2373 line were observed. Results suggest that a plethora of cell signaling pathways associated with cell survival are induced by Dox but inhibited by the addition of Van in MM. Data from our study support the combined efficacy of Van and Dox as a novel approach in the treatment of MM that is further enhanced by blocking ERK5 or CREB signaling cascades. PMID:24940987

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

    SciTech Connect

    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

    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.

  14. Iontophoresis of cyclic AMP.

    PubMed Central

    Cohen, M H; Drage, D J; Robertson, A

    1975-01-01

    The design, calibration, and operation of a source of controlled amounts of cyclic AMP (c-AMP) are described. Typically, 1.5 s pulses containing 10(10)-10(-12) molecules of c-AMP can be delivered to a region about 10 mum in diameter on an agar plate. The resulting concentration profiles are given as functions of distance and time. The diffusion coefficient of c-AMP in agar was measured to be 0.97 times 10(-5) cm2-s-1 at 21 degrees C. PMID:167878

  15. The isolated frog skin epithelium: Permeability characteristics and responsiveness to oxytocin, cyclic AMP and theophylline

    Microsoft Academic Search

    R. M. Rajerison; M. Montegut; S. Jard; F. Morel

    1972-01-01

    The combined treatment of the frog skin with collagenase and hydrostatic pressure enables complete separation of the epithelial layer from the supporting dermis. The separation entirely preserves the epithelium's passive permeability and active sodium transport capacity. The short circuit current, d.c. resistance, unidirectional fluxes of Na+ and Cl- ions, and osmotic water permeability were found identical on series of isolated

  16. Recovery of beta-adrenoceptors and cyclic AMP response after long term treatment of intact heart cells with beta-blockers.

    PubMed Central

    Becker, C.; Porzig, H.

    1984-01-01

    We have studied the recovery of receptor binding and of isoprenaline-stimulated cyclic AMP responses after chronic (2-5 days) exposure of tissue-cultured living rat heart cells to several beta-adrenoceptor antagonists. Most experiments were performed with [3H]- (+/-)-carazolol and [3H]-(+/-)-CGP 12177, as prototypes of high affinity lipophilic and hydrophilic ligands respectively. Chronic antagonist treatment did not alter the total number of receptors nor did it cause intracellular accumulation of the ligands. At the end of the treatment, radiolabelled antagonists were displaced either by 'infinite' dilution of the incubation medium or by competitive displacement with the non-labelled ligand (-)-timolol. In dilution assays dissociation of carazolol from specific sites was biphasic with t 1/2 values of 41 +/- 14 and 219 +/- 15 min. Dissociation of CGP 12177 was monophasic with t 1/2 of 102 +/- 2 min. Timolol enhanced the dissociation rates of both radioligands and suppressed the slow phase of carazolol dissociation. Isoprenaline-stimulated cyclic AMP formation did not recover in parallel with the release of the two antagonists from receptor binding sites. To reach about 80% of control values for receptor availability or cyclic AMP response required 3 h and 24 h washout periods, respectively, after carazolol (0.2 nM) treatment, or 1.5 and 12 h washout periods after CGP 12177 (4 nM) treatment. Such a 'decoupling' effect was not observed during recovery from chronic exposure to the antagonists, timolol and propranolol. We conclude that some antagonists cause a novel form of desensitization that is not linked to their partial agonistic potency. Moreover, carazolol-type drugs seem to induce an additional isomeric form of the beta-receptor that is not recognized by other antagonists. These observations could explain the well known discrepancy between long duration of action and rapid removal from the circulation of several antagonists in current therapeutic use. PMID:6146370

  17. Terminal neuroendocrine differentiation of human prostate carcinoma cells in response to increased intracellular cyclic AMP.

    PubMed

    Bang, Y J; Pirnia, F; Fang, W G; Kang, W K; Sartor, O; Whitesell, L; Ha, M J; Tsokos, M; Sheahan, M D; Nguyen, P; Niklinski, W T; Myers, C E; Trepel, J B

    1994-06-01

    Recent clinicopathologic studies have shown that many prostatic adenocarcinomas express focal neuroendocrine differentiation and that neuroendocrine differentiation is most apparent in advanced anaplastic tumors. While studying growth-regulatory signal transduction events in human prostate carcinoma cell lines, we found that in two of four cell lines, the androgen-sensitive line LNCaP and the highly metastatic androgen-independent line PC-3-M, elevation of cAMP through addition of cAMP analogues or phosphodiesterase inhibitors induced a markedly neuronal morphology. Also in LNCaP cells ultrastructural analysis showed that cAMP induced the appearance of neurosecretory cell-like dense-core granules. Phenotypic analysis of untreated LNCaP and PC-3-M cells showed that both cell lines express markers of the neural crest including S-100, chromogranin A, pp60c-src, and neuron-specific enolase as well as the epithelial marker KS1/4 and stage-specific embryonic antigen 4. In PC-3-M cells, cAMP markedly elevated neuron-specific enolase protein and caused an increase in the specific activity of the neuroendocrine marker pp60c-src, and in both cell lines expression of KS1/4 and stage-specific embryonic antigen 4 was down-regulated. In addition to effects on lineage markers, cAMP treatment induced G1 synchronization, growth arrest, and loss of clonogenicity, indicating terminal differentiation. Our data provide direct evidence of plasticity in the lineage commitment of adenocarcinoma of the prostate. We have shown that cell-permeant cAMP analogues can induce terminal differentiation, suggesting that hydrolysis-resistant cyclic nucleotides may present an additional approach to the treatment of advanced prostate cancer. PMID:8202489

  18. Terminal neuroendocrine differentiation of human prostate carcinoma cells in response to increased intracellular cyclic AMP.

    PubMed Central

    Bang, Y J; Pirnia, F; Fang, W G; Kang, W K; Sartor, O; Whitesell, L; Ha, M J; Tsokos, M; Sheahan, M D; Nguyen, P

    1994-01-01

    Recent clinicopathologic studies have shown that many prostatic adenocarcinomas express focal neuroendocrine differentiation and that neuroendocrine differentiation is most apparent in advanced anaplastic tumors. While studying growth-regulatory signal transduction events in human prostate carcinoma cell lines, we found that in two of four cell lines, the androgen-sensitive line LNCaP and the highly metastatic androgen-independent line PC-3-M, elevation of cAMP through addition of cAMP analogues or phosphodiesterase inhibitors induced a markedly neuronal morphology. Also in LNCaP cells ultrastructural analysis showed that cAMP induced the appearance of neurosecretory cell-like dense-core granules. Phenotypic analysis of untreated LNCaP and PC-3-M cells showed that both cell lines express markers of the neural crest including S-100, chromogranin A, pp60c-src, and neuron-specific enolase as well as the epithelial marker KS1/4 and stage-specific embryonic antigen 4. In PC-3-M cells, cAMP markedly elevated neuron-specific enolase protein and caused an increase in the specific activity of the neuroendocrine marker pp60c-src, and in both cell lines expression of KS1/4 and stage-specific embryonic antigen 4 was down-regulated. In addition to effects on lineage markers, cAMP treatment induced G1 synchronization, growth arrest, and loss of clonogenicity, indicating terminal differentiation. Our data provide direct evidence of plasticity in the lineage commitment of adenocarcinoma of the prostate. We have shown that cell-permeant cAMP analogues can induce terminal differentiation, suggesting that hydrolysis-resistant cyclic nucleotides may present an additional approach to the treatment of advanced prostate cancer. Images PMID:8202489

  19. 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

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

    2013-05-01

    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

  20. 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

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

    1991-01-01

    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. PMID:1687369

  1. Cyclic AMP Receptor Protein-Aequorin Molecular Switch for Cyclic AMP

    PubMed Central

    Scott, Daniel; Hamorsky, Krystal Teasley; Ensor, C. Mark; Anderson, Kimberly W.; Daunert, Sylvia

    2011-01-01

    Molecular switches are designer molecules that combine the functionality of two individual proteins into one, capable of manifesting an “on/off” signal in response to a stimulus. These switches have unique properties and functionalities and thus, can be employed as nanosensors in a variety of applications. To that end, we have developed a bioluminescent molecular switch for cyclic AMP. Bioluminescence offers many advantages over fluorescence and other detection methods including the fact that there is essentially zero background signal in physiological fluids, allowing for more sensitive detection and monitoring. The switch was created by combining the properties of the cyclic AMP receptor protein (CRP), a transcriptional regulatory protein from E. coli that binds selectively to cAMP with those of aequorin, a bioluminescent photoprotein native of the jellyfish Aequorea victoria. Genetic manipulation to split the genetic coding sequence of aequorin in two and genetically attach the fragments to the N and C termini of CRP, resulted in a hybrid protein molecular switch. The conformational change experienced by CRP upon the binding of cyclic AMP is suspected to result in the observed loss of bioluminescent signal from aequorin. The “on/off” bioluminescence can be modulated by cyclic AMP over a range of several orders of magnitude in a linear fashion in addition to the capacity to detect changes in cellular cyclic AMP of intact cells exposed to different external stimuli without the need to lyse the cells. We envision that the molecular switch could find applications in vitro as well as in vivo cyclic AMP detection and/or imaging. PMID:21329338

  2. Cyclic AMP selectively enhances bradykinin receptor synthesis and expression in cultured arterial smooth muscle. Inhibition of angiotensin II and vasopressin response.

    PubMed Central

    Dixon, B S

    1994-01-01

    Bradykinin receptors on vascular smooth muscle may play an important role in regulating the endogenous effects of the vascular kallikrein-kinin system. The present study examined the effect of cyclic nucleotides on bradykinin-stimulated responses in cultured arterial smooth muscle cells. Short term stimulation (1 min) with cyclic AMP produced a variable inhibition of bradykinin-stimulated calcium mobilization which was lost in later passaged cells. However, long-term stimulation (24 h) produced a consistent increase in bradykinin-stimulated calcium mobilization in both early and late passaged cells. Further analysis demonstrated that chronic exposure to cAMP produced a twofold increase in both the number of cell surface bradykinin receptors and in bradykinin-stimulated phosphoinositide hydrolysis. The increase in bradykinin receptors was time dependent (> 7 h) and blocked by protein synthesis inhibitors, suggesting that cAMP enhanced the synthesis of new bradykinin receptors. The increase in bradykinin receptor binding and calcium mobilization was also stimulated by cholera toxin, forskolin, and isobutylmethylxanthine, but not isoproterenol or prostaglandin E2. Of considerable interest, prolonged exposure to cAMP inhibited both angiotensin II and arginine vasopressin-stimulated phosphoinositide hydrolysis and intracellular calcium mobilization. In summary, prolonged treatment with cAMP selectively stimulates the synthesis and expression of bradykinin receptors on arterial smooth muscle while decreasing the responsiveness to vasoconstrictor agonists such as angiotensin II and vasopressin. Images PMID:8200990

  3. Stimulation of GCMa Transcriptional Activity by Cyclic AMP/Protein Kinase A Signaling Is Attributed to CBP-Mediated Acetylation of GCMa†

    PubMed Central

    Chang, Ching-Wen; Chuang, Hsiao-Ching; Yu, Chenchou; Yao, Tso-Pang; Chen, Hungwen

    2005-01-01

    Human GCMa is a zinc-containing transcription factor primarily expressed in placenta. GCMa regulates expression of syncytin gene, which encodes for a placenta-specific membrane protein that mediates trophoblastic fusion and the formation of syncytiotrophoblast layer required for efficient fetal-maternal exchange of nutrients and oxygen. The adenylate cyclase activator, forskolin, stimulates syncytin gene expression and cell fusion in cultured placental cells. Here we present evidence that cyclic AMP (cAMP) signaling pathway activates the syncytin gene expression by regulating GCMa activity. We found that forskolin and protein kinase A (PKA) enhances GCMa-mediated transcriptional activation. Furthermore, PKA treatment stimulates the association of GCMa with CBP and increases GCMa acetylation. CBP primarily acetylates GCMa at lysine367, lysine406, and lysine409 in the transactivation domain (TAD). We found that acetylation of these residues is required to protect GCMa from ubiquitination and increases the TAD stability with a concomitant increase in transcriptional activity, supporting the importance of acetylation in PKA-dependent GCMa activation. Our results reveal a novel regulation of GCMa activity by cAMP-dependent protein acetylation and provide a molecular mechanism by which cAMP signaling regulates trophoblastic fusion. PMID:16166624

  4. Cyclic AMP Signaling: A Molecular Determinant of Peripheral Nerve Regeneration

    PubMed Central

    Knott, Eric P.; Assi, Mazen; Pearse, Damien D.

    2014-01-01

    Disruption of axonal integrity during injury to the peripheral nerve system (PNS) sets into motion a cascade of responses that includes inflammation, Schwann cell mobilization, and the degeneration of the nerve fibers distal to the injury site. Yet, the injured PNS differentiates itself from the injured central nervous system (CNS) in its remarkable capacity for self-recovery, which, depending upon the length and type of nerve injury, involves a series of molecular events in both the injured neuron and associated Schwann cells that leads to axon regeneration, remyelination repair, and functional restitution. Herein we discuss the essential function of the second messenger, cyclic adenosine monophosphate (cyclic AMP), in the PNS repair process, highlighting the important role the conditioning lesion paradigm has played in understanding the mechanism(s) by which cyclic AMP exerts its proregenerative action. Furthermore, we review the studies that have therapeutically targeted cyclic AMP to enhance endogenous nerve repair. PMID:25177696

  5. Competitive Inhibition of Beef Heart Cyclic AMP Phosphodiesterase by Cytokinins and Related Compounds

    PubMed Central

    Hecht, Sidney M.; Faulkner, Robert D.; Hawrelak, S. D.

    1974-01-01

    Two cytokinins and four related analogs, none of which is a cyclic ribonucleotide, have been shown to act as competitive inhibitors of the high Km cyclic-AMP phosphodiesterase (3?:5?-cyclic-AMP 5?-nucleotidohydrolase, EC 3.1.4.17) activity from beef heart. Weak inhibition of the low Km cyclic AMP phosphodiesterase activity was also observed, suggesting a possible mechanism for regulation of intracellular cyclic AMP levels by the exogenously added compounds. In addition to the kinetic data, obtained on the six inhibitors in four different heterocyclic series, 15 other cytokinins and related compounds have been shown to inhibit the high Km cyclic AMP phosphodiesterase activity at single concentrations of substrate and inhibitor. Heterocycles such as adenosine and 7-amino-3-methylpyrazolo[4,3-d]pyrimidine, which lack the N-substituent, were inactive as cyclic AMP phosphodiesterase inhibitors. The observed inhibition of cyclic AMP phophodiesterase supports prior observations which implicate exogenously added cytokinins in cyclic AMP metabolism. PMID:4373727

  6. Identification of calcium-dependent and -independent signaling pathways involved in polychlorinated biphenyl-induced cyclic AMP-responsive element-binding protein phosphorylation in developing cortical neurons 1 1 This article has been reviewed by the National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, and is approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use

    Microsoft Academic Search

    J. R Inglefield; W. R Mundy; C. A Meacham; T. J Shafer

    2002-01-01

    Cyclic AMP (cAMP)-responsive element-binding protein (CREB) is a transcription factor important in developing nervous system cells and is activated by a variety of signaling molecules. Aroclor 1254 (A1254), a polychlorinated biphenyl mixture, perturbs Ca2+ homeostasis and increases CREB phosphorylation in rat neonatal cortical cell cultures in a time- and concentration-dependent manner. The present experiments determined that the cell type responding

  7. Analysis of the human dopamine beta-hydroxylase promoter: transcriptional induction by cyclic AMP.

    PubMed

    Lamouroux, A; Houhou, L; Biguet, N F; Serck-Hanssen, G; Guibert, B; Icard-Liepkalns, C; Mallet, J

    1993-01-01

    We have analyzed some functional aspects of the promoter of the human dopamine beta-hydroxylase (DBH) gene. A fragment of 1,247 bp directly 5' to the transcriptional start was progressively shortened, placed in front of a reporter gene, and tested in a human neuroblastoma cell line expressing DBH (SK-N-SH-TFM) and in a monkey kidney cell line (CV-1). A remarkably short region (267 bp), directly upstream from the transcription start, was sufficient to confer activity and tissue-specific expression. Furthermore, the expression of the DBH gene was shown to be inducible by cyclic AMP in SK-N-SH-TFM cells. This effect was demonstrated to occur at the transcriptional level, as shown by run-on assays, and was due to the presence of a near-consensus cyclic AMP-responsive element located in the untranscribed 5' regulatory region of the gene. PMID:8380196

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

    ERIC Educational Resources Information Center

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

    2008-01-01

    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…

  9. Differential regulation of Raf-1 and B-Raf and Ras-dependent activation of mitogen-activated protein kinase by cyclic AMP in PC12 cells.

    PubMed Central

    Erhardt, P; Troppmair, J; Rapp, U R; Cooper, G M

    1995-01-01

    Growth factor stimulation of the mitogen-activated protein (MAP) kinase pathway in fibroblasts is inhibited by cyclic AMP (cAMP) as a result of inhibition of Raf-1. In contrast, cAMP inhibits neither nerve growth factor-induced MAP kinase activation nor differentiation in PC12 pheochromocytoma cells. Instead, in PC12 cells cAMP activates MAP kinase. Since one of the major differences between the Ras/Raf/MAP kinase cascades of these cell types is the expression of B-Raf in PC12 cells, we compared the effects of cAMP on Raf-1 and B-Raf. In PC12 cells maintained in serum-containing medium, B-Raf was refractory to inhibition by cAMP, whereas Raf-1 was effectively inhibited. In contrast, both B-Raf and Raf-1 were inhibited by cAMP in serum-starved PC12 cells. The effect of cAMP is thus dependent upon growth conditions, with B-Raf being resistant to cAMP inhibition in the presence of serum. These results were extended by studies of Rat-1 fibroblasts into which B-Raf had been introduced by transfection. As in PC12 cells, B-Raf was resistant to inhibition by cAMP in the presence of serum, whereas Raf-1 was effectively inhibited. In addition, the expression of B-Raf rendered Rat-1 cells resistant to the inhibitory effects of cAMP on both growth factor-induced activation of MAP kinase and mitogenesis. These results indicate that Raf-1 and B-Raf are differentially sensitive to inhibition by cAMP and that B-Raf expression can contribute to cell type-specific differences in the regulation of the MAP kinase pathway. In contrast to the situation in PC12 cells, cAMP by itself did not stimulate MAP kinase in B-Raf-expressing Rat-1 cells. The activation of MAP kinase by cAMP in PC12 cells was inhibited by the expression of a dominant negative Ras mutant, indicating that cAMP acts on a target upstream of Ras. Thus, it appears that a signaling component upstream of Ras is also require for cAMP stimulation of MAP kinase in PC12 cells. PMID:7565704

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

    NASA Astrophysics Data System (ADS)

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

    1988-12-01

    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.

  11. Activation of endogenous anti-inflammatory mediator cyclic AMP attenuates acute pyelonephritis in mice induced by uropathogenic Escherichia coli.

    PubMed

    Wei, Yang; Li, Ke; Wang, Na; Cai, Gui-Dong; Zhang, Ting; Lin, Yan; Gui, Bao-Song; Liu, En-Qi; Li, Zong-Fang; Zhou, Wuding

    2015-02-01

    The pathogenesis of pyelonephritis caused by uropathogenic Escherichia coli (UPEC) is not well understood. Here, we show that besides UPEC virulence, the severity of the host innate immune response and invasion of renal epithelial cells are important pathogenic factors. Activation of endogenous anti-inflammatory mediator cAMP significantly attenuated acute pyelonephritis in mice induced by UPEC. Administration of forskolin (a potent elevator of intracellular cAMP) reduced kidney infection (ie, bacterial load, tissue destruction); this was associated with attenuated local inflammation, as evidenced by the reduction of renal production of proinflammatory mediators, renal infiltration of inflammatory cells, and renal myeloperoxidase activity. In primary cell culture systems, forskolin not only down-regulated UPEC-stimulated production of proinflammatory mediators by renal tubular epithelial cells and inflammatory cells (eg, monocyte/macrophages) but also reduced bacterial internalization by renal tubular epithelial cells. Our findings clearly indicate that activation of endogenous anti-inflammatory mediator cAMP is beneficial for controlling UPEC-mediated acute pyelonephritis in mice. The beneficial effect can be explained at least in part by limiting excessive inflammatory responses through acting on both renal tubular epithelial cells and inflammatory cells and by inhibiting bacteria invasion of renal tubular epithelial cells. PMID:25478807

  12. CRP-Cyclic AMP Dependent Inhibition of the Xylene-Responsive ?54-Promoter Pu in Escherichia coli

    PubMed Central

    Tian, Zhe-Xian; Huo, Yi-Xin; Sun, Yi-Cheng; Wang, Yi-Ping

    2014-01-01

    The expression of ?54-dependent Pseudomonas putida Pu promoter is activated by XylR activator when cells are exposed to a variety of aromatic inducers. In this study, the transcriptional activation of the P. putida Pu promoter was recreated in the heterologous host Escherichia coli. Here we show that the cAMP receptor protein (CRP), a well-known carbon utilization regulator, had an inhibitory effect on the expression of Pu promoter in a cAMP-dependent manner. The inhibitory effect was not activator specific. In vivo KMnO4 and DMS footprinting analysis indicated that CRP-cAMP poised the RNA polymerase at Pu promoter, inhibiting the isomerization step of the transcription initiation even in the presence of an activator. Therefore, the presence of PTS-sugar, which eliminates cAMP, could activate the poised RNA polymerase at Pu promoter to transcribe. Moreover, the activation region 1 (AR1) of CRP, which interacts directly with the ?CTD (C-terminal domain of ?-subunit) of RNA polymerase, was found essential for the CRP-mediated inhibition at Pu promoter. A model for the above observations is discussed. PMID:24466213

  13. Activation of Cyclic AMP Synthesis by Full and Partial Beta-Adrenergic Receptor Agonists in Chicken Skeletal Muscle Cells

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Bridge, K. Y.; Cureri, Peter A. (Technical Monitor)

    2002-01-01

    Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Accordingly, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax concentrations were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. When cimaterol and clenbuterol were added to culture media at concentrations known to cause significant muscle hypertrophy in animals, there was no detectable effect on stimulation of cAMP synthesis. Finally, these same levels of cimaterol and clenbuterol did not antagonize the stimulation of cAMP by either epinephrine or isoproterenol.

  14. Activation of Cyclic AMP Synthesis by Full and Partial Beta-Adrenergic Receptor Agonists in Chicken Skeletal Muscle Cells

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Bridge, K. Y.

    2003-01-01

    Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Accordingly, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate CAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of CAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of CAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax concentrations were approximately 15-fold weaker than isoproterenol in stimulating the rate of CAMP synthesis. When cimaterol and clenbuterol were added to culture media at concentrations known to cause significant muscle hypertrophy in animals, there was no detectable effect on stimulation of CAMP synthesis. Finally, these same levels of cimaterol and clenbuterol did not antagonize the stimulation of CAMP by either epinephrine or isoproterenol.

  15. 21 CFR 862.1230 - Cyclic AMP test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...DEVICES Clinical Chemistry Test Systems § 862.1230 Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure...the diagnosis and treatment of endocrine disorders, including...

  16. 21 CFR 862.1230 - Cyclic AMP test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...DEVICES Clinical Chemistry Test Systems § 862.1230 Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure...the diagnosis and treatment of endocrine disorders, including...

  17. 21 CFR 862.1230 - Cyclic AMP test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...DEVICES Clinical Chemistry Test Systems § 862.1230 Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure...the diagnosis and treatment of endocrine disorders, including...

  18. 21 CFR 862.1230 - Cyclic AMP test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...DEVICES Clinical Chemistry Test Systems § 862.1230 Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure...the diagnosis and treatment of endocrine disorders, including...

  19. 21 CFR 862.1230 - Cyclic AMP test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...DEVICES Clinical Chemistry Test Systems § 862.1230 Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure...the diagnosis and treatment of endocrine disorders, including...

  20. Looking downstream: the role of cyclic AMP-regulated genes in axonal regeneration

    PubMed Central

    Siddiq, Mustafa M.; Hannila, Sari S.

    2015-01-01

    Elevation of intracellular cyclic AMP (cAMP) levels has proven to be one of the most effective means of overcoming inhibition of axonal regeneration by myelin-associated inhibitors such as myelin-associated glycoprotein (MAG), Nogo, and oligodendrocyte myelin glycoprotein. Pharmacological manipulation of cAMP through the administration of dibutyryl cAMP or rolipram leads to enhanced axonal growth both in vivo and in vitro, and importantly, upregulation of cAMP within dorsal root ganglion neurons is responsible for the conditioning lesion effect, which indicates that cAMP plays a significant role in the endogenous mechanisms that promote axonal regeneration. The effects of cAMP are transcription-dependent and are mediated through the activation of protein kinase A (PKA) and the transcription factor cyclic AMP response element binding protein (CREB). This leads to the induction of a variety of genes, several of which have been shown to overcome myelin-mediated inhibition in their own right. In this review, we will highlight the pro-regenerative effects of arginase I (ArgI), interleukin (IL)-6, secretory leukocyte protease inhibitor (SLPI), and metallothionein (MT)-I/II, and discuss their potential for therapeutic use in spinal cord injury. PMID:26150769

  1. Induction of nitric oxide synthase in cultured vascular smooth muscle cells: the role of cyclic AMP.

    PubMed Central

    Hirokawa, K.; O'Shaughnessy, K.; Moore, K.; Ramrakha, P.; Wilkins, M. R.

    1994-01-01

    1. Interleukin-1 beta (IL-1 beta) is a potent stimulant of inducible nitric oxide synthase (iNOS) mRNA and nitric oxide (NO) production in vascular smooth muscle (VSM) cells in culture. These studies investigate the role of adenosine 3':5'-cyclic monophosphate (cyclic AMP) in this process. 2. Dibutyryl cyclic AMP (db cyclic AMP, 0.1-1 mM), forskolin (1-10 microM) and the phosphodiesterase inhibitor, Ro 20-1724 (1-10 microM), all of which increase intracellular cyclic AMP, had no effect on NO production when added alone but markedly enhanced NO production by IL-1 beta-stimulated VSM cells in a dose-dependent manner. Consistent with a cyclic AMP-mediated action, isoprenaline (1-10 microM) increased NO production from IL-1 beta-stimulated cells. Dibutyryl cyclic GMP (db cyclic GMP) had no effect at concentrations up to 1 mM. 3. Pursuing these observations, iNOS protein levels were examined by Western blot analysis and iNOS mRNA levels were measured by reverse transcription and amplification of the resultant cDNA using the polymerase chain reaction. In addition to enhancing NO production, db cyclic AMP increased iNOS protein and mRNA above that produced by IL-1 beta alone. 4. These data demonstrate a major effect of cyclic AMP on cytokine-induced NOS activity in VSM cells, mediated at least in part by regulating synthesis of iNOS, and has implications for the pathogenesis and management of septic shock. Images Figure 6 Figure 7 PMID:7521256

  2. Effects of probenecid on transport and metabolism of cyclic AMP by isolated rabbit renal tubules.

    PubMed

    Podevin, R A; Boumendil-Podevin, E F; Bujoli-Roche, J; Priol, C

    1980-04-17

    The effects of probenecid on the transport and metabolism of cyclic [14C]-AMP were studied in isolated rabbit kidney cortex tubules. Incubation in a medium with 10-400 microM probenecid for 30 min caused a 30-70% decrease in the tubular uptake of labeled material from a medium containing 0.1 mM cyclic [14C]AMP. The radioactivity in the tubules, after 30 min incubation, with or without probenecid, was mostly in the form of inosine and hypoxanthine. The disappearance of external cyclic [14C]AMP was retarded by probenecid and the concentration ratio of cyclic AMP to inosine + hypoxanthine was increased. Cyclic AMP phosphodiesterase activities, from both the soluble and particulate fractions of the kidney, were inhibited by probenecid. These findings indicate that the changes caused by probenecid on the renal disposal of extracellular cyclic AMP can be accounted for by a decrease in the accumulation of the products of cyclic AMP metabolism secondary to inhibition of extracellular cyclic AMP phosphodiesterase activity. PMID:6245714

  3. Long-term regulation of synaptic acetylcholine release and nicotinic transmission: the role of cyclic AMP.

    PubMed Central

    Briggs, C. A.; McAfee, D. A.; McCaman, R. E.

    1988-01-01

    1. Using the rat superior cervical ganglion in vitro, the relative efficacy of nicotinic synaptic transmission was estimated by recording the postganglionic compound action potential and the amount of endogenous acetylcholine (ACh) released. These two parameters were correlated in individual ganglia by sampling the bathing medium for the assay of ACh while simultaneously recording the postganglionic response. 2. The beta-adrenoceptor agonist isoprenaline potentiated both the evoked release of ACh and the postganglionic response by about 20% during preganglionic stimulation at 0.2 Hz. 3. The adenosine receptor agonist 2-chloroadenosine inhibited ACh release and the postganglionic response by about 35%. 4. Tetanic preganglionic stimulation for a few seconds induced a long-term potentiation of nicotinic responses and of ACh release. Both of these potentiations were dependent upon extracellular Ca2+ during the tetani. 5. Forskolin and analogues of cyclic AMP also caused a long-lasting potentiation of both the evoked release of ACh and the postganglionic response, indicating that cyclic AMP may regulate transmission by a presynaptic mechanism. The specificity of the cyclic AMP analogues was tested using various butyryl- and bromo-purine nucleotides. 6. The effects of forskolin and 8-bromo-cyclic AMP did not appear to be dependent upon extracellular Ca2+. 7. The potentiation caused by forskolin was consistently augmented by three phosphodiesterase inhibitors--AH 21-132, papaverine and SQ 20-006. However, the effect of forskolin was not consistently enhanced by theophylline, nor was it reduced by the adenylate cyclase inhibitor SQ 22-536. 8. The neurogenic long-term potentiation was augmented by two of the phosphodiesterase inhibitors that also augmented the forskolin-induced potentiation--papaverine and SQ 20-006. 9. It was concluded that cyclic AMP can enhance nicotinic transmission, and can do so by increasing the evoked release of ACh. However, it was not possible to prove that cyclic AMP mediates the long-term potentiation induced by tetanic preganglionic stimulation. PMID:2833971

  4. Vasopressin potentiates the noradrenaline-induced accumulation of cyclic AMP in the rat superior cervical ganglion.

    PubMed

    Petit, P; Barberis, C; Jard, S

    1988-02-01

    Previous experiments gave biochemical and electrophysiological evidence for the presence of functional V1-vasopressin receptors coupled to inositol lipid metabolism, but not to cyclic AMP accumulation in the rat superior cervical ganglion. This work was designed to investigate whether there was an action of vasopressin on the noradrenaline-induced cyclic AMP accumulation through the activation of phospholipase C. Our results clearly demonstrate that arginine-vasopressin potentiates cyclic AMP accumulation induced by noradrenaline or isoproterenol in a concentration-dependent manner. The potentiation was unaffected by phentolamine, but was suppressed by the V1-type vasopressin receptor antagonists. Moreover, the phorbol ester 4 beta-phorbol-12-myristate-13-acetate (TPA) did not affect this potentiation which seemed to be Ca2+-dependent. The results suggest that vasopressin may modulate the activity of autonomous functions in the sympathetic ganglia. PMID:2833995

  5. Regulation of Cyclic AMP Formation in Brain Tissue by alpha -adrenergic Receptors: Requisite Intermediacy of Prostaglandins of the E Series

    Microsoft Academic Search

    Curtis R. Partington; Michael W. Edwards; John W. Daly

    1980-01-01

    The accumulations of cyclic AMP elicited by norepinephrine in slices of rat cerebral cortex or hypothalamus were markedly reduced after incubations with prostaglandin synthetase (8,11,14-eicosatrienoate, hydrogen-donor:oxygen oxidoreductase, EC 1.14.99.1) inhibitors such as indomethacin, aspirin, flufenamic acid, and acetoaminophen. Responses of cyclic AMP-generating systems to beta -adrenergic agonists or adenosine were unchanged by treatment with indomethacin and the reduction in the

  6. Comparison between the effects of inhaled isoprenaline and fenoterol on plasma cyclic AMP and heart rate in normal subjects.

    PubMed Central

    Fairfax, A J; Rehahn, M; Jones, D; O'Malley, B

    1984-01-01

    The time course of changes in plasma cyclic AMP, heart rate and bronchial tone after inhalation of fenoterol or isoprenaline from a dose-metered aerosol are reported in a group of normal subjects. After isoprenaline, plasma cyclic AMP increased rapidly reaching a peak by 10 min and returned to basal levels within 60 min. A rapid, transient rise in heart rate occurred that was maximal by 5 min and returned to a basal level by 45 min. After fenoterol, the changes in cyclic AMP and heart rate were of much longer duration. The rise in plasma cyclic AMP was slower in onset and of greater magnitude than for isoprenaline, reaching a peak by 20 min and remaining above basal level for more than 6 h. The maximum increase in heart rate after fenoterol was less than that observed with isoprenaline but an elevated rate persisted for 4 h after inhalation of fenoterol. Fenoterol is known to have a longer duration of action as a bronchodilator in comparison with isoprenaline. The prolonged rise in plasma cyclic AMP in normal subjects given inhaled fenoterol may reflect this long duration of action. The concomitant rise in heart rate, however, suggests that the duration of plasma cyclic AMP response may in part be due to the systemic effect of the fraction of inhaled fenoterol known to be absorbed via the buccal and intestinal routes. PMID:6322828

  7. Adenosine receptor-induced cyclic AMP generation and inhibition of 5-hydroxytryptamine release in human platelets.

    PubMed Central

    Cooper, J A; Hill, S J; Alexander, S P; Rubin, P C; Horn, E H

    1995-01-01

    1. We have assessed the effects of adenosine receptor agonists and antagonists on collagen-induced 5-hydroxytryptamine (5-HT) release and cyclic AMP generation in human platelets. 2. 5'-N-ethylcarboxamidoadenosine (NECA) and CGS 21680 elicited accumulations of cyclic AMP with mean EC50 values of 2678 and 980 nM, respectively. The maximal response to CGS 21680 was approximately half that of the response to 10 microM NECA. 3. NECA and CGS 21680 inhibited collagen-induced 5-hydroxytryptamine release with mean EC50 values of 960 and 210 nM, respectively. The maximal response to CGS 21680 was approximately 25% of the response to 10 microM NECA. 4. The A1/A2a-selective adenosine receptor antagonist PD 115,199 was more potent as an inhibitor of NECA-elicited responses than the A1-selective antagonist DPCPX with calculated Ki values of 22-32 nM and > 10 microM, respectively. 5. In the presence of a cyclic AMP phosphodiesterase inhibitor, the effects of CGS 21680 on cyclic AMP accumulation and 5-HT release were enhanced to levels similar to those elicited by 10 microM NECA. In the absence of phosphodiesterase inhibition, CGS 21680 did not antagonise the effects of NECA. Furthermore, endogenous adenosine did not contribute to the effects of CGS 21680 when phosphodiesterase was inhibited. 6. We conclude that an A2a adenosine receptor appears to be involved in the NECA-elicited increases in cyclic AMP levels and inhibition of 5-HT release in human platelets.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8527267

  8. Cyclic AMP system in muscle tissue during prolonged hypokinesia

    NASA Technical Reports Server (NTRS)

    Antipenko, Y. A.; Bubeyev, Y. A.; Korovkin, B. F.; Mikhaleva, N. P.

    1980-01-01

    Components of the cyclic Adenosine-cyclic-35-monophosphate (AMP) system in the muscle tissue of white rats were studied during 70-75 days of hypokinesia, created by placing the animals in small booths which restricted their movements, and during the readaptation period. In the initial period, cyclic AMP levels and the activities of phosphodiesterase and adenylate cyclase in muscle tissue were increased. The values for these indices were roughly equal for controls and experimental animals during the adaptation period, but on the 70th day of the experiment cAMP levels dropped, phosphodiesterase activity increased, and the stimulative effect of epinephrine on the activity of adenylate cyclase decreased. The indices under study normalized during the readaptation period.

  9. Bidirectional Regulation of the Cyclic-AMP Response Element Binding Protein Encodes Spatial Map Alignment in Prism-Adapting Barn Owls

    PubMed Central

    Nichols, Grant S; DeBello, William M

    2012-01-01

    The barn owl midbrain contains mutually aligned maps of auditory and visual space. Throughout life, map alignment is maintained through the actions of an instructive signal that encodes the magnitude of auditory-visual mismatch. The intracellular signaling pathways activated by this signal are unknown. Here we tested the hypothesis that CREB (cAMP response element binding protein) provides a cell-specific readout of instructive information. Owls were fitted with prismatic or control spectacles and provided rich auditory-visual experience - hunting live mice. CREB activation was analyzed within 30 minutes of hunting using phosphorylation state-specific (pCREB) and CREB antibodies, confocal imaging and immunofluorescence measurements at individual cell nuclei. In control owls or prism-adapted owls, which experience small instructive signals, the frequency distributions of pCREB/CREB values obtained for cell nuclei within the external nucleus of the inferior colliculus (ICX) were unimodal. In contrast, in owls adapting to prisms or re-adapting to normal conditions, the distributions were bimodal: certain cells had received a signal that positively regulated CREB, and by extension, transcription of CREB-dependent genes, while others a signal that negatively regulated it. These changes were restricted to the sub-region of the inferior colliculus that received optically displaced input, the rostral ICX, and not evident in the caudal ICX or central nucleus. Finally, the topographic pattern of CREB regulation was patchy, not continuous, as expected from the actions of a topographically precise signal encoding discrete events. These results support a model in which the magnitude of CREB activation within individual cells provides a readout of the instructive signal that guides plasticity and learning. PMID:18829948

  10. A functional cyclic AMP response element plays a crucial role in neuroendocrine cell type-specific expression of the secretory granule protein chromogranin A.

    PubMed Central

    Wu, H; Mahata, S K; Mahata, M; Webster, N J; Parmer, R J; O'Connor, D T

    1995-01-01

    Chromogranin A, a soluble acidic protein, is a ubiquitous component of secretory vesicles throughout the neuroendocrine system. We reported previously the cloning and initial characterization of the mouse chromogranin A gene promoter, which showed that the promoter contains both positive and negative domains and that a proximal promoter spanning nucleotides -147 to +42 bp relative to the transcriptional start site is sufficient for neuroendocrine cell type-specific expression. The current study was undertaken to identify the particular elements within this proximal promoter that control tissue-specific expression. We found that deletion or point mutations in the potential cAMP response element (CRE) site at -68 bp virtually abolished promoter activity specifically in neuroendocrine (PC12 chromaffin or AtT20 corticotrope) cells, with little effect on activity in control (NIH3T3 fibroblast) cells; thus, the CRE box is necessary for neuroendocrine cell type-specific activity of the chromogranin A promoter. Furthermore, the effect of the CRE site is enhanced in the context of intact (wild-type) promoter sequences between -147 and -100 bp. DNase I footprint analysis showed that these regions (including the CRE box) bind nuclear proteins present in both neuroendocrine (AtT20) and control (NIH3T3) cells. In AtT20 cells, electrophoretic mobility shift assays and factor-specific antibody supershifts showed that an oligonucleotide containing the chromogranin A CRE site formed a single, homogeneous protein-DNA complex containing the CRE-binding protein CREB. However, in control NIH3T3 cells we found evidence for an additional immunologically unrelated protein in this complex. A single copy of this oligonucleotide was able to confer neuroendocrine-specific expression to a heterologous (thymidine kinase) promoter, albeit with less fold selectivity than the full proximal chromogranin A promoter. Hence, the CRE site was partially sufficient to explain the neuroendocrine cell type specificity of the promoter. The functional activity of the CRE site was confirmed through studies of the endogenous chromogranin A gene. Northern mRNA analysis showed that expression of the endogenous chromogranin A gene was stimulated seven- to eightfold by cAMP in PC12 cells, whereas no induction occurred in the NIH3T3 cells. Similar cAMP induction was obtained with the transfected chromogranin A promoter in PC12 cells, and abolition of the CRE site (by deletion or point mutation) eliminated the induction. Thus, the CRE site in the chromogranin A proximal promoter is functional and plays a crucial, indeed indispensable, role in neuroendocrine-specific expression of the gene. These results also provide insight into transcriptional mechanisms governing acquisition of the neuroendocrine secretory phenotype. Images PMID:7615829

  11. Synthesis and properties of some cyclic AMP alkyl phosphotriesters

    PubMed Central

    Gohil, R.N.; Gillen, R.G.; Nagyvary, J.

    1974-01-01

    Cyclic AMP was converted to its phosphotriesters according to the classical approach of phosphate activation with a sulfonyl chloride, followed by esterification with an alcohol. The methyl, ethyl, propyl, butyl and cetyl triesters were prepared, and some of their physical-chemical properties determined. Alkaline hydrolysis of these alkyl phosphotriesters resulted predominantly in ring opening. On the other hand, nucleophilic attack by thiourea led to the formation of cAMP as the main product. The conclusion can be drawn from these results that cAMP phosphotriesters could serve as suitable storage forms of cAMP, and cyclic triesters may be the best vehicle of transporting nucleotides through biological membranes. PMID:4375277

  12. Synthesis and properties of some cyclic AMP alkyl phosphotriesters.

    PubMed

    Gohil, R N; Gillen, R G; Nagyvary, J

    1974-12-01

    Cyclic AMP was converted to its phosphotriesters according to the classical approach of phosphate activation with a sulfonyl chloride, followed by esterification with an alcohol. The methyl, ethyl, propyl, butyl and cetyl triesters were prepared, and some of their physical-chemical properties determined. Alkaline hydrolysis of these alkyl phosphotriesters resulted predominantly in ring opening. On the other hand, nucleophilic attack by thiourea led to the formation of cAMP as the main product. The conclusion can be drawn from these results that cAMP phosphotriesters could serve as suitable storage forms of cAMP, and cyclic triesters may be the best vehicle of transporting nucleotides through biological membranes. PMID:4375277

  13. Cyclic AMP-dependent and Epac-mediated activation of R-ras by G protein-coupled receptors leads to phospholipase D stimulation

    Microsoft Academic Search

    Jesus de M. L; M. B. Stope; P. A. O. Weernink; Y. Mahlke; C. Boergermann; V. N. Ananaba; C. Rimmbach; D. Rosskopf; M. C. Michel; K. H. Jakobs; M. Schmidt

    2006-01-01

    The activation of the Ras-related GTPase R-Ras, which has been implicated in the regulation of various cellular functions, by G protein-coupled receptors (GPCRs) was studied in HEK293 cells stably expressing the M-3 muscarinic acetylcholine receptor ( mAChR), which can couple to several types of heterotrimeric G proteins. Activation of the receptor induced a very rapid and transient activation of R-Ras.

  14. Activation of 3':5'-cyclic AMP-dependent protein kinase and induction of ornithine decarboxylase as early events in induction of mixed-function oxygenases.

    PubMed Central

    Byus, C V; Costa, M; Sipes, I G; Brodie, B B; Russell, D H

    1976-01-01

    The parenteral administration of a single dose of 3-methylcholanthrene to rats caused an increase in the liver of the concentration of 3', 5'-cAMP and of the activity of cAMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37). These events were followed by an increased activity of ornithine decarboxylase (L-ornithine carboxy-lase, EC 4.1.1.17), the enzyme that controls the biosynthesis of polyamines. Finally, the activity of benzo[a]pyrene hydroxylase, as well as the amount of cytochrome P-448, was increased. Similarly, after the administration of phenobarbital, there was first an increase in the cAMP concentration and in the activity of cAMP-dependent protein kinase, then the induction of ornithine decarboxylase, and finally, an enhanced activity of ethylmorphine N-demethylase and an increased content of cytochrome P-450. These data suggest that the drug-induced processes in liver that increase the activities of the oxidative, and presumably other, drug-metabolizing enzymes include the following sequence of events: (1) increase in cAMP concentration and/or activation of cAMP-dependent protein kinase; (2) induction of ornithine decarboxylase; and, (3) induction of drug-metabolizing enzymes. PMID:177981

  15. 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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 cAMP receptor protein (CRP) indirectly increases ltxA expression...

  16. Detection and investigation of a protein factor concerned with the stimulation of disulfide reductase activity by cyclic AMP and other effectors

    Microsoft Academic Search

    V. I. Kulinskii; L. S. Kolesnichenko

    1976-01-01

    Stimulation of disulfide reductase (DSR) in the supernatant fraction of mouse liver by 3',5'-AMP (10-7 M), ATP (5·10-5 M), Mg++ (5·10-5 M), EDTA (5·10-4 M), and protamine (5 mg\\/ml) is mediated by a factor which is readily adsorbed by BaSO4, Al(OH)3, and activated charcoal, and is readily eluted by a tenfold increase in the molarity of the buffer. Barium eluates

  17. Stimulation of GCMa Transcriptional Activity by Cyclic AMP\\/Protein Kinase A Signaling Is Attributed to CBP-Mediated Acetylation of GCMa

    Microsoft Academic Search

    Ching-Wen Chang; Hsiao-Ching Chuang; Chenchou Yu; Tso-Pang Yao; Hungwen Chen

    2005-01-01

    Human GCMa is a zinc-containing transcription factor primarily expressed in placenta. GCMa regulates expression of syncytin gene, which encodes for a placenta-specific membrane protein that mediates tropho- blastic fusion and the formation of syncytiotrophoblast layer required for efficient fetal-maternal exchange of nutrients and oxygen. The adenylate cyclase activator, forskolin, stimulates syncytin gene expression and cell fusion in cultured placental cells.

  18. Mutations that alter the charge of type I regulatory subunit and modify activation properties of cyclic AMP-dependent protein kinase from S49 mouse lymphoma cells.

    PubMed

    Steinberg, R A; Gorman, K B; Ogreid, D; Døskeland, S O; Weber, I T

    1991-02-25

    Mutations in regulatory (R) subunit of cAMP-dependent protein kinase were analyzed from cAMP-resistant mutants of S49 mouse lymphoma cells by direct sequencing of amplified regions of mutant R subunit cDNAs. Eight distinct single base-change lesions were identified in 24 independent mutants that were hemizygous for expression of mutant R subunits with altered protein charge. CG----TA transitions predominated, but AT----GC transitions and GC----TA transversions were also observed. Four of five spontaneous mutants had identical C----T transitions at CG causing substitution of Trp for Arg-334. Sites mutated in isolates obtained after mutagenesis with ethyl methanesulfonate or N-methyl-N'-nitro-N-nitrosoguanidine were more varied. Six of the lesions (two in binding site A and four in site B) were at amino acid residues that are highly conserved among cAMP-binding sites of R subunits and the Escherichia coli catabolite activator protein. These mutations all either prevented or strongly hindered binding of cyclic nucleotides to the mutated site. One of the remaining lesions (at Arg-242) also prevented cyclic nucleotide binding to the mutated binding site; the other (at Gly-170) had only minimal effects on binding of cyclic nucleotides but, nevertheless, increased the apparent constant for cAMP-dependent kinase activation. These results are discussed with reference to a model for the cAMP-binding sites of R subunit based on the crystal structure of the E. coli catabolite activator protein. PMID:1847378

  19. Regulation of cyclic AMP phosphodiesterase from human lung tissue by nucleosides and nucleotides

    E-print Network

    Glass, William Fredrick

    1978-01-01

    Hypothetical mechanism for catalysis of' cyclic AMP hydrolysis by phosphodiesterase enzymes 45 INTRODUGTION Cyclic nucleotide levels are important in modulating the i. mmunological release and effects of various mediators in allergic bronchial asthma.... Phos hodiesterase Assa s ? Two methods were used to assay phosphodiesterase activity. One method was that of Thompson snd. Appleman (24). For this method the final reaction volume was 400pl containing 20mM Mg012, 4mM 8-mercaptoethanol and. 50mM Tris...

  20. Inhibition of carbonic anhydrase by parathyroid hormone and cyclic AMP in rat renal cortex in vitro.

    PubMed Central

    Beck, N; Kim, K S; Wolak, M; Davis, B B

    1975-01-01

    It has been demonstrated that parathyroid hormone (PTH) inhibits the proximal tubular reabsorption of bicarbonate, and increases the urinary excretion of that ion. There is also a qualitative similarity between the alterations of the proximal tubular reabsorption of phosphate, sodium, and water after PTH administration and after acetazolamide administration. These findings suggest that the renal effect of PTH is possibly mediated through the inhibition of carbonic anhydrase in proximal tubules. Therefore, a possible inhibitory effect of PTH on carbonic anhydrase was evaluated in the homogenate of rat renal cortex by an indicator titration method. Incubation of cortical homogenates with PTH for 10 min at 37degreesC inhibited carbonic anhydrase activity. The inhibitory effect of PTH was ATP-, Mg++-, and K+-dependent and temperature-dependent; inactivation of PTH by heating at 100degreesC abolished the effect of PTH both to activate adenylate cyclase and to inhibit carbonic anhydrase. Calcium 5 mM also partially abolished effects of PTH to activate adenylate cyclase and to inhibit carbonic anhydrase. The inhibitory effect of PTH on carbonic anhydrase was specific to renal cortex. Cyclic AMP, the intracellular messenger substance for PTH, also inhibited carbonic anhydrase in renal cortex. The cyclic AMP-induced inhibition was also Mg++ dependent and temperature dependent, and required preincubation at 37degreesC. But 5'-AMP, a metabolic derivative of cyclic AMP without its biological effect, had no inhibitory effect on carbonic anhydrase. All the above results are consistent with the hypothesis that PTH inhibits proximal tubular reabsorption of bicarbonate and phosphate through the inhibition of carbonic anhydrase, and that inhibitory effect is mediated through the cyclic AMP system. PMID:233968

  1. Spatial encoding of cyclic AMP signalling specificity by GPCR endocytosis

    PubMed Central

    Tsvetanova, Nikoleta G.; von Zastrow, Mark

    2014-01-01

    G protein-coupled receptors (GPCRs) are well known to signal via cyclic AMP (cAMP) production at the plasma membrane, but it is now clear that various GPCRs also signal after internalization. Apart from its temporal impact through prolonging the cellular response, does the endosome-initiated signal encode any discrete spatial information? Using the beta2-adrenoceptor (?2-AR) as a model, we show that endocytosis is required for the full repertoire of downstream cAMP-dependent transcriptional control. Next, we describe an orthogonal optogenetic approach to definitively establish that the location of cAMP production is indeed the critical variable determining the transcriptional response. Finally, our results suggest that this spatial encoding scheme helps cells functionally discriminate chemically distinct ?2-AR ligands according to differences in their ability to promote receptor endocytosis. These findings reveal a discrete principle for achieving cellular signalling specificity, based on endosome-mediated spatial encoding of intracellular second messenger production and ‘location aware’ downstream transcriptional control. PMID:25362359

  2. Spatial encoding of cyclic AMP signaling specificity by GPCR endocytosis.

    PubMed

    Tsvetanova, Nikoleta G; von Zastrow, Mark

    2014-12-01

    G protein-coupled receptors (GPCRs) are well known to signal via cyclic AMP (cAMP) production at the plasma membrane, but it is now clear that various GPCRs also signal after internalization. Apart from its temporal impact through prolonging the cellular response, we wondered whether the endosome-initiated signal encodes any discrete spatial information. Using the ?2-adrenoceptor (?2-AR) as a model, we show that endocytosis is required for the full repertoire of downstream cAMP-dependent transcriptional control. Next, we describe an orthogonal optogenetic approach to definitively establish that the location of cAMP production is indeed the critical variable determining the transcriptional response. Finally, our results suggest that this spatial encoding scheme helps cells functionally discriminate chemically distinct ?2-AR ligands according to differences in their ability to promote receptor endocytosis. These findings reveal a discrete principle for achieving cellular signaling specificity based on endosome-mediated spatial encoding of intracellular second messenger production and 'location-aware' downstream transcriptional control. PMID:25362359

  3. Food restriction increases NMDA receptor-mediated calcium-calmodulin kinase II and NMDA receptor/extracellular signal-regulated kinase 1/2-mediated cyclic amp response element-binding protein phosphorylation in nucleus accumbens upon D-1 dopamine receptor stimulation in rats.

    PubMed

    Haberny, S L; Carr, K D

    2005-01-01

    Biological drive states exert homeostatic control in part by increasing the reinforcing effects of environmental incentive stimuli. An apparent by-product of this adaptive response is the enhanced acquisition of drug self-administration behavior in food-restricted (FR) animals. While previous research has demonstrated increased central sensitivity to rewarding effects of abused drugs and direct dopamine (DA) receptor agonists in FR subjects, the underlying neurobiology is not well understood. Recently, it was demonstrated that intracerebroventricular (i.c.v.) injection of the D-1 DA receptor agonist, SKF-82958 produces a stronger activation of striatal extracellular signal-regulated kinase (ERK) 1/2 and cyclic AMP response element-binding protein (CREB) in FR relative to ad libitum (AL) fed rats. The main purpose of the present study was to characterize the involvement and mechanisms of interaction between NMDA receptor function and the augmented cellular responses to D-1 DA receptor stimulation in nucleus accumbens (NAc) of FR rats. In experiment 1, Western immunoblotting was used to demonstrate that i.c.v. injection of SKF-82958 (20 microg) produces greater phosphorylation of the NMDA NR1 subunit and calcium-calmodulin kinase II (CaMK II) in NAc of FR as compared with AL rats. In experiment 2, pretreatment of subjects with the NMDA antagonist, MK-801 (1.0 mg/kg, i.p.) decreased SKF-82958-induced activation of CaMK II, ERK1/2 and CREB, and reversed the augmenting effect of FR on activation of all three proteins. In experiment 3, pretreatment with the mitogen-activated protein kinase/ERK kinase inhibitor SL-327 (60 mg/kg, i.p.) suppressed SKF-82958- induced activation of ERK1/2 and reversed the augmenting effect of FR on CREB activation. These results point to specific neuroadaptations in the NAc of FR rats whereby D-1 DA receptor stimulation leads to increased NMDA NR1 subunit phosphorylation and consequent increases in NMDA receptor-dependent CaMK II and ERK1/2 signaling, and increased NMDA receptor/ERK1/2-dependent phosphorylation of the nuclear transcription factor, CREB. The upregulated cellular responses to D-1 DA agonist challenge may play a role in the augmentation of drug reward and appetitive instrumental learning during periods of food restriction. PMID:15857708

  4. Electrical Stimulation Decreases Coupling Efficiency Between Beta-Adrenergic Receptors and Cyclic AMP Production in Cultured Muscle Cells

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Bridge, K. Y.

    1999-01-01

    Electrical stimulation of skeletal muscle cells in culture is an effective way to simulate the effects of muscle contraction and its effects on gene expression in muscle cells. Expression of the beta-adrenergic receptor and its coupling to cyclic AMP synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy, and the goal of this project was to determine if electrical stimulation altered the beta-adrenergic response in muscle cells. Chicken skeletal muscle cells that had been grown for seven days in culture were subjected to electrical stimulation for an additional two days at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. At the end of this two-day stimulation period, beta-adrenergic receptor population was measured by the binding of tritium-labeled CGP-12177 to muscle cells, and coupling to cAMP synthesis was measured by Radioimmunoassay (RIA) after treating the cells for 10 min with the potent (beta)AR agonist, isoproterenol. The number of beta adrenergic receptors and the basal levels of intracellular cyclic AMP were not affected by electrical stimulation. However, the ability of these cells to synthesize cyclic AMP was reduced by approximately 50%. Thus, an enhanced level of contraction reduces the coupling efficiency of beta-adrenergic receptors for cyclic AMP production.

  5. Myoblast fusion is regulated by a prostanoid of the one series independently of a rise in cyclic AMP

    PubMed Central

    1986-01-01

    The role of prostanoids in the regulation of chick myoblast differentiation has been investigated. At 3 X 10(-6) M, indomethacin and chloroquine specifically inhibit cell fusion. They do not affect cell proliferation, alignment, or the expression of two muscle-specific proteins, namely, the acetylcholine receptor and the muscle-specific form of creatine phosphokinase. The results demonstrate that it is indomethacin's activity as an inhibitor of prostaglandin synthesis at the cyclooxygenase step that causes the block of cell fusion, whereas chloroquine probably acts at the earlier step of phospholipase A. Prostaglandin E1 (PGE1), but not prostaglandin E2 (PGE2), rapidly reverses the inhibition of fusion imposed by indomethacin or chloroquine. The dose response of the myoblasts to PGE1 is a bell- shaped curve with a 100% reversal of fusion at approximately 10(-9) M. Eicosatrienoate and linoleate reverse the inhibition of fusion with similar kinetics, whereas arachidonate is completely ineffective. The ability of PGE1 and eicosatrienoate but not PGE2 and arachidonate to restore fusion to control levels implies that fusion is specifically regulated by a prostanoid of the one series. The reversal of the fusion- block by linoleate further suggests that this fatty acid provides the necessary source of eicosatrienoate in the myoblast plasma membrane. At 10(-8) M and above, PGE1 and PGE2 stimulate adenylate cyclase and depress control fusion as does 10(-5) M isoproterenol. The beta- adrenergic blocker propranolol abolishes both isoproterenol's inhibition of myoblast fusion and its activation of adenylate cyclase. The similar depressions imposed on cell fusion by 10(-8)-10(-6) M prostanoid and 10(-5) M isoproterenol suggest that in both cases the depressive effects are mediated by cyclic AMP. It is concluded that a prostanoid of the one series regulates fusion by a cyclic AMP- independent mechanisms. PMID:3017999

  6. Stereospecificity of rolipram actions on eosinophil cyclic AMP-specific phosphodiesterase.

    PubMed

    Souness, J E; Scott, L C

    1993-04-15

    The stereospecificity of rolipram inhibition of particulate cyclic AMP-specific phosphodiesterase (PDE IV) from guinea-pig eosinophils has been investigated. (-)-Rolipram (IC50 = 0.22 +/- 0.08 microM) was 2.5-fold more potent than (+)-rolipram (IC50 = 0.58 +/- 0.05 microM) in inhibiting membrane-bound PDE IV. Solubilization of PDE IV with deoxycholate (0.5%) and NaCl (100 mM) increased rolipram stereospecificity [IC50 (-)-rolipram = 0.020 +/- 0.002 microM; IC50 (+)-rolipram = 0.33 +/- 0.07 microM]. Partial purification of this solubilized PDE IV by DEAE-trisacryl anion-exchange chromatography reduced the enantiomeric potency difference compared with the pre-chromatographed activity, with (-)-rolipram (IC50 = 0.20 +/- 0.02 microM) being only 2.9-fold more potent than (+)-rolipram (IC50 = 0.57 +/- 0.14 microM). Vanadate-glutathione complex (V-GSH) stimulated membrane-bound PDE IV activity and increased the potency of (-)-rolipram (IC50 = 0.014 +/- 0.006 microM) but not (+)-rolipram (IC50 = 0.32 +/- 0.07 microM). In intact eosinophils, (-)-rolipram (EC50 = 0.19 +/- 0.02 microM) was 10-fold more potent than (+)-rolipram (EC50 = 1.87 +/- 0.09 microM) in enhancing isoprenaline (10 microM)-stimulated cyclic AMP accumulation. Strong correlations were demonstrated for displacement of [3H]rolipram binding to brain membranes by several PDE inhibitors and their inhibition of solubilized PDE IV (r = 0.98, P < 0.001, n = 7) and stimulation of cyclic AMP accumulation in intact cells (r = 0.98, P < 0.001, n = 6). Rolipram was a relatively weak inhibitor of partially purified pig aortic PDE IV and only slight stereospecificity was exhibited [IC50 (-)-rolipram = 1.47 +/- 0.09 microM; IC50 (+)-rolipram = 2.73 +/- 0.38 microM]. The results indicate the presence of a partially concealed stereospecific site (Sr) on eosinophil PDE IV possibly similar to the high-affinity rolipram-binding site in brain through which rolipram can potently inhibit enzyme activity. This site, which apparently is not present on partially purified pig aortic PDE IV, is concealed in freshly prepared eosinophil membranes but is exposed by solubilization or V-GSH treatment and is important in regulating intracellular cyclic AMP accumulation in intact cells. PMID:8387267

  7. Sustained signalling by PTH modulates IP3 accumulation and IP3 receptors through cyclic AMP junctions

    PubMed Central

    Meena, Abha; Tovey, Stephen C.; Taylor, Colin W.

    2015-01-01

    ABSTRACT Parathyroid hormone (PTH) stimulates adenylyl cyclase through type 1 PTH receptors (PTH1R) and potentiates the Ca2+ signals evoked by carbachol, which stimulates formation of inositol 1,4,5-trisphosphate (IP3). We confirmed that in HEK cells expressing PTH1R, acute stimulation with PTH(1-34) potentiated carbachol-evoked Ca2+ release. This was mediated by locally delivered cyclic AMP (cAMP), but unaffected by inhibition of protein kinase A (PKA), exchange proteins activated by cAMP, cAMP phosphodiesterases (PDEs) or substantial inhibition of adenylyl cyclase. Sustained stimulation with PTH(1-34) causes internalization of PTH1R–adenylyl cyclase signalling complexes, but the consequences for delivery of cAMP to IP3R within cAMP signalling junctions are unknown. Here, we show that sustained stimulation with PTH(1-34) or with PTH analogues that do not evoke receptor internalization reduced the potentiated Ca2+ signals and attenuated carbachol-evoked increases in cytosolic IP3. Similar results were obtained after sustained stimulation with NKH477 to directly activate adenylyl cyclase, or with the membrane-permeant analogue of cAMP, 8-Br-cAMP. These responses were independent of PKA and unaffected by substantial inhibition of adenylyl cyclase. During prolonged stimulation with PTH(1-34), hyperactive cAMP signalling junctions, within which cAMP is delivered directly and at saturating concentrations to its targets, mediate sensitization of IP3R and a more slowly developing inhibition of IP3 accumulation. PMID:25431134

  8. Renal handling of 3?-5?-cyclic AMP in the rat

    Microsoft Academic Search

    D. Butlen; S. Jard

    1972-01-01

    3'-5'-cyclic AMP, phosphate and calcium renal excretions were studied in rats in different physiological states and submitted to various hormonal treatments: Lysine-vasopressin, parathormone (PTH) and glucagon injections. Simultaneous measurement of the specific radioactivities of 3'-5'-cyclic AMP in plasma and urine during steady state infusion of tracer, amounts of3H 3'-5'-cyclic AMP made it possible to determine the contributions of renal synthesis

  9. Phosphorylation of  -Catenin by Cyclic AMP-Dependent Protein Kinase Stabilizes  -Catenin through Inhibition of Its Ubiquitination

    Microsoft Academic Search

    Shin-ichiro Hino; Chie Tanji; Keiichi I. Nakayama; Akira Kikuchi

    2005-01-01

    The mechanism of cross talk between the Wnt signaling and cyclic AMP (cAMP)-dependent protein kinase (protein kinase A (PKA)) pathways was studied. Prostaglandin E1 (PGE1), isoproterenol, and dibutyryl cAMP (Bt2cAMP), all of which activate PKA, increased the cytoplasmic and nuclear -catenin protein level, and these actions were suppressed by a PKA inhibitor and RNA interference for PKA. PGE1 and Bt2cAMP

  10. IDENTIFICATION OF A SEA URCHIN Na+\\/K+\\/2Cl COTRANSPORTER (NKCC): MICROFILAMENT-DEPENDENT SURFACE EXPRESSION IS MEDIATED BY HYPOTONIC SHOCK AND CYCLIC AMP

    Microsoft Academic Search

    GREGG R. STROHMEIER; BERNARD ROSSI; PAUL HOFMAN

    We report the identification of an invertebrate Na+\\/K+\\/2Cl- cotransporter, NKCC. As a model system, we used the immune cells (coelomocytes) of the Mediterranean sea urchin Paracentrotus lividus. These cells are particularly interesting because they can be activated to undergo a rapid and dynamic change in cell shape. We demonstrate that forskolin, a cyclic AMP agonist known to regulate NKCC, induced

  11. Effect of electrical stimulation on beta-adrenergic receptor population and cyclic amp production in chicken and rat skeletal muscle cell cultures

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Bridge, K. Y.; Strietzel, C. J.

    2000-01-01

    Expression of the beta-adrenergic receptor (betaAR) and its coupling to cyclic AMP (cAMP) synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy, and the goal of this study was to determine if electrical stimulation in a pattern simulating slow muscle contraction would alter the betaAR response in primary cultures of avian and mammalian skeletal muscle cells. Specifically, chicken skeletal muscle cells and rat skeletal muscle cells that had been grown for 7 d in culture were subjected to electrical stimulation for an additional 2 d at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. In chicken skeletal muscle cells, the betaAR population was not significantly affected by electrical stimulation; however, the ability of these cells to synthesize cyclic AMP was reduced by approximately one-half. In contrast, the betaAR population in rat muscle cells was increased slightly but not significantly by electrical stimulation, and the ability of these cells to synthesize cyclic AMP was increased by almost twofold. The basal levels of intracellular cyclic AMP in neither rat muscle cells nor chicken muscle cells were affected by electrical stimulation.

  12. On the mechanism of action of lead in the testis: in vitro suppression of FSH receptors, cyclic AMP and steroidogenesis. [Rats

    SciTech Connect

    Wiebe, J.P.; Salhanick, A.I.; Myers, K.I.

    1983-04-25

    The purpose of the present study was to determine by in vitro methods, if Pb acts by interfering directly with hormone binding, cyclic AMP production and steroidogenic enzyme activity. Sertoli cells were isolated from testes of prepubertal rats and cultured in the presence of 2.64 x 10/sup -4/ M of either NaAc (control) or PbAc for 1, 4, 24, 48, 96 or 144 hr. There was no reduction in FSH binding and in FSH-induced cyclic AMP after a 1-4 hr exposure to Pb. After a 24-hr exposure to Pb, the cells exhibited a 10-20% decrease in FSH binding and cyclic AMP production and after 96 hr there was a 75% decrease in these 2 parameters. The inhibition was greater in cells from 16 day old than from 20 day old rats, so that in the former, after a 144 hr exposure the FSH-induced cyclic AMP of the Pb exposed cells was only 3% of the amount produced by the NaAc exposed cells (i.e. a 97% inhibition). After in vitro exposure to Pb for 48 hr, the steroidogenic activity (progesterone conversion to steroid metabolites) of Sertoli cells was significantly reduced and their steroidogenesis was no longer stimulated by FSH. A crude testicular enzyme preparation containing 3..beta..-hydroxysteroid dehydrogenase (3..beta..-HSD) exhibited approximately 25% reduction in activity if the assay buffer contained PbCl/sub 2/ instead of the equivalent in NaCl. Prolonged in vivo exposure to Pb resulted in approximately 50% reduction in 3..beta..-HSD activity. This is the first indication that in the testis Pb may act directly (immediate effect) by suppressing enzyme activities, and indirectly (long term effect) by reducing gonadotropin-receptor binding and the resultant cyclic AMP production.

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

    PubMed Central

    Matthiesen, Karina; Nielsen, Jacob

    2011-01-01

    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

  14. Cholera toxin, and the related nontoxic adjuvants mmCT and dmLT, promote human Th17 responses via cyclic AMP-protein kinase A and inflammasome-dependent IL-1 signaling.

    PubMed

    Larena, Maximilian; Holmgren, Jan; Lebens, Michael; Terrinoni, Manuela; Lundgren, Anna

    2015-04-15

    We have examined the molecular pathways involved in the adjuvant action of cholera toxin (CT) and two novel nontoxic molecules, multiple-mutated CT (mmCT) and double-mutant heat-labile toxin (dmLT) on human T cell responses. Human PBMCs or isolated monocytes were stimulated in vitro with CT, mmCT, or dmLT plus a polyclonal stimulus (staphylococcal enterotoxin B) or specific bacterial Ags, and effects on expression of cytokines and signaling molecules were determined. CT, mmCT, and dmLT strongly enhanced IL-17A and to a lesser extent IL-13 responses, but had little effect on IFN-? production or cell proliferation. Intracellular cytokine staining revealed that the enhanced IL-17A production was largely confined to CD4(+) T cells and coculture experiments showed that the IL-17A promotion was effectively induced by adjuvant-treated monocytes. Relative to CT, mmCT and dmLT induced at least 100-fold lower levels of cAMP, yet this cAMP was enough and essential for the promotion of Th17 responses. Thus, inhibition of cAMP-dependent protein kinase A was abolished, and stimulation with a cAMP analog mimicked the adjuvant effect. Furthermore, CT, mmCT, and dmLT induced IL-1? production and caspase-1 activation in monocytes, which was associated with increased expression of key proinflammatory and inflammasome-related genes, including NLRP1, NLRP3, and NLRC4. Inflammasome inhibition with a specific caspase-1 inhibitor, or blocking of IL-1 signaling by IL-1 receptor antagonist, abrogated the Th17-promoting effect. We conclude that CT, mmCT, and dmLT promote human Th17 responses via cAMP-dependent protein kinase A and caspase-1/inflammasome-dependent IL-1 signaling. PMID:25786687

  15. A Novel Cyclic AMP/Epac1/CaMKI Signaling Cascade Promotes GCM1 Desumoylation and Placental Cell Fusion ?

    PubMed Central

    Chang, Ching-Wen; Chang, Geen-Dong; Chen, Hungwen

    2011-01-01

    Cyclic AMP (cAMP) signaling and the placental transcription factor glial cell missing 1 (GCM1) regulate expression of syncytin-1 and -2 fusogenic proteins, which are critical for syncytiotrophoblast formation by trophoblast fusion. We recently revealed a cAMP/protein kinase A (PKA)/CBP signaling pathway that activates GCM1 by coordinating GCM1 phosphorylation and acetylation. In contrast, GCM1 activity is downregulated by sumoylation of Lys156. How GCM1 sumoylation is regulated was unknown. Here, we identify a novel PKA-independent cAMP signaling pathway as the critical regulator of GCM1 sumoylation. We show that Epac1 and Rap1, in response to cAMP, activate CaMKI to phosphorylate Ser47 in GCM1. This phosphorylation facilitates the interaction between GCM1 and the desumoylating enzyme SENP1 and thereby leads to GCM1 desumoylation and activation. Using RNA interference (RNAi), we further demonstrate that 8-(4-chlorophenylthio)-2?-O-Me-cAMP-AM (8-CPT-AM), an Epac activator, stimulates syncytin-1 and -2 gene expression and cell fusion of placental BeWo cells in a GCM1-dependent manner. Importantly, the cell fusion defect in GCM1-knockdown BeWo cells can be reversed and enhanced by the RNAi-resistant phosphomimetic GCM1(S47D) mutant. Our study has identified a novel cAMP/Epac1/CaMKI/GCM1 signaling cascade that stimulates trophoblast fusion through promoting GCM1 phosphorylation and desumoylation. PMID:21791615

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

    NSDL National Science Digital Library

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

    1996-01-26

    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.

  17. Involvement of microtubules in the regulation of Bcl2 phosphorylation and apoptosis through cyclic AMP-dependent protein kinase.

    PubMed

    Srivastava, R K; Srivastava, A R; Korsmeyer, S J; Nesterova, M; Cho-Chung, Y S; Longo, D L

    1998-06-01

    The Bcl2 family of proteins plays a significant role in regulation of apoptosis. In this study, the microtubule-damaging drugs paclitaxel, vincristine, and vinblastine induced Bcl2 hyperphosphorylation and apoptosis in MCF-7 and MDA-MB-231 cells and reduced Bcl2-Bax dimerization. Paclitaxel or vincristine induced increased expression of Bax, while overexpression of Bcl2 in these cell lines counteracted the effects of low doses of these drugs. In addition, paclitaxel- and vincristine-induced activation of cyclic AMP (cAMP)-dependent protein kinase (protein kinase A [PKA]) induced Bcl2 hyperphosphorylation and apoptosis, which were blocked by the PKA inhibitor Rp diastereomers of cAMP (Rp-cAMP). This finding suggests that activation of PKA due to microtubule damage is an important event in Bcl2 hyperphosphorylation and induction of apoptosis. These microtubule-damaging drugs caused growth arrest in G2-M phase of the cell cycle and had no effect on p53 induction, suggesting that hyperphosphorylation mediated inactivation of Bcl2 and apoptosis without the involvement of p53. By comparison, the DNA-damaging drugs methotrexate and doxorubicin had no effect on Bcl2 hyperphosphorylation but induced p53 expression. Interestingly, paclitaxel or vincristine induced activation of caspase 3 and cleavage of poly(ADP-ribose) polymerase downstream of Bcl2 hyperphosphorylation. These data suggest that there may be a signaling cascade induced by agents that disrupt or damage the cytoskeleton that is distinct from (i.e., p53 independent), but perhaps related to (i.e., involves kinase activation and leads to apoptosis), the cellular response to DNA damage. PMID:9584191

  18. Regulation of the sodium/potassium/chloride cotransporter by calcium and cyclic AMP in cultured vascular smooth muscle cells

    SciTech Connect

    Higgins, B.L.; Smith, L.; Smith, J.B.

    1987-05-01

    The activity of the Na/K/Cl cotransporter in smooth muscle cells cultured from rat aorta was assayed by measuring the initial rate of furosemide-inhibitable /sup 86/Rb influx or efflux. Five uM furosemide or 0.2 uM bumetanide inhibited influx by 50%. Furosemide-inhibitable /sup 86/Rb influx depended on the presence of all 3 ions in the external medium. The dependence on Na and K was hyperbolic with apparent Km values of 45 and 5 mM, respectively. The dependence on Cl was sigmoidal. Assuming a stoichiometry of 1:1:2 for Na:K:Cl, a Km for Cl of 60 mM was obtained from a Hofstee plot of the data. Rapidly growing cells had 3 fold higher cotransport activity than quiescent cells. Angiotensin II (ANG) stimulated furosemide-inhibitable /sup 86/Rb efflux by 2 fold. An ANG receptor antagonist prevented ANG from increasing cotransport activity. Two calcium ionophores, A23187 and ionomycin, increased cotransport activity by 2 fold. Phorbol myristate acetate had no effect on cotransport activity. Isoproterenol, dibutyryl cyclic AMP, cholera toxin, or methylisobutylxanthine inhibited furosemide-sensitive /sup 86/Rb influx by 35 to 50%. From these findings they conclude that increasing cytoplasmic free calcium stimulates cotransport activity, whereas increasing cellular cyclic AMP inhibits the cotransporter.

  19. Ecklonia cava Polyphenol Has a Protective Effect against Ethanol-Induced Liver Injury in a Cyclic AMP-Dependent Manner

    PubMed Central

    Yamashita, Haruka; Goto, Mayu; Matsui-Yuasa, Isao; Kojima-Yuasa, Akiko

    2015-01-01

    Previously, we showed that Ecklonia cava polyphenol (ECP) treatment suppressed ethanol-induced increases in hepatocyte death by scavenging intracellular reactive oxygen species (ROS) and maintaining intracellular glutathione levels. Here, we examined the effects of ECP on the activities of alcohol-metabolizing enzymes and their regulating mechanisms in ethanol-treated hepatocytes. Isolated hepatocytes were incubated with or without 100 mM ethanol. ECP was dissolved in dimethylsulfoxide. ECP was added to cultured cells that had been incubated with or without ethanol. The cells were incubated for 0–24 h. In cultured hepatocytes, the ECP treatment with ethanol inhibited cytochrome P450 2E1 (CYP2E1) expression and activity, which is related to the production of ROS when large quantities of ethanol are oxidized. On the other hand, ECP treatment with ethanol increased the activity of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase. These changes in activities of CYP2E1 and ADH were suppressed by treatment with H89, an inhibitor of protein kinase A. ECP treatment with ethanol enhanced cyclic AMP concentrations compared with those of control cells. ECP may be a candidate for preventing ethanol-induced liver injury via regulating alcohol metabolic enzymes in a cyclic AMP-dependent manner. PMID:26096275

  20. Cyclic AMP (cAMP)-Mediated Stimulation of Adipocyte Differentiation Requires the Synergistic Action of Epac and cAMP-Dependent Protein Kinase-Dependent Processes

    Microsoft Academic Search

    Rasmus Koefoed Petersen; Lise Madsen; Lone Møller Pedersen; Philip Hallenborg; H. Hagland; K. Viste; S. O. Doskeland; K. Kristiansen

    2008-01-01

    Cyclic AMP (cAMP)-dependent processes are pivotal during the early stages of adipocyte differentiation. We show that exchange protein directly activated by cAMP (Epac), which functions as a guanine nucleotide exchange factor for the Ras-like GTPases Rap1 and Rap2, was required for cAMP-dependent stimulation of adipocyte differentiation. Epac, working via Rap, acted synergistically with cAMP-dependent protein kinase (protein kinase A (PKA))

  1. Reduced sensitivity of the hepatic adenylate cyclase-cyclic AMP system to glucagon during sustained hormonal stimulation.

    PubMed Central

    DeRubertis, F R; Craven, P

    1976-01-01

    Hormone-induced desensitization of hormonal regulation of cyclic AMP (cAMP) content has been described in a number of tissues. In the present study, we examined responses of rat liver to glucagon after periods of sustained exposure to the hormone in vivo and in vitro. In intact anesthetized rats infused with glucagon (50 ng/min) for 1 h or more and in liver slices incubated with the hormone (10 muM) for this period, hepatic cAMP responsiveness to glucagon was significantly blunted compared with that of tissue exposed to the hormone for shorter periods. The reduction in hepatic cAMP responsiveness to glucagon appeared to be fully expressed by 2 h. With the doses of hormone employed, the sequential alterations in hepatic responsiveness seemed to be limited to the cAMP system, since other parameters of glucagon action did not wane with time. Diminished hepatic cAMP responsiveness during sustained hormonal exposure could not be attributed to decreased glucagon availability, accelerated extracellular release of cAMP, hepatic ATP depletion, or enhanced phosphodiesterase activity. Studies in vitro suggested that modulation of the cAMP response occurred at the level of adenylate cyclase (AC). During sustained exposure of hepatic slices to glucagon, reductions in glucagon-responsive AC correlated temporally with those in cAMP and both changes were reversible. Alterations in glucagon-responsive AC were demonstrated over a wide range of ATP (10 muM-0.1 mM) and glucagon (10 nM-5 MM) concentrations in the cyclase reaction mixture, and appeared to be a noncompetitive phenomenon relative to glucagon. Maximal NaF-responsive AC did not fall concomitantly with time. Thus, the reduction in glucagon-responsive AC was probably not related to a reduction in the catalytic unit of the enzyme, but could have been due to an alteration in glucagon binding to its receptor sites, or in the coupling mechanism involved in transmission of the hormonal signal to the catalytic unit. Images PMID:176180

  2. Inhibition of the Raf-1 kinase by cyclic AMP agonists causes apoptosis of v-abl-transformed cells.

    PubMed Central

    Weissinger, E M; Eissner, G; Grammer, C; Fackler, S; Haefner, B; Yoon, L S; Lu, K S; Bazarov, A; Sedivy, J M; Mischak, H; Kolch, W

    1997-01-01

    Here we investigate the role of the Raf-1 kinase in transformation by the v-abl oncogene. Raf-1 can activate a transforming signalling cascade comprising the consecutive activation of Mek and extracellular-signal-regulated kinases (Erks). In v-abl-transformed cells the endogenous Raf-1 protein was phosphorylated on tyrosine and displayed high constitutive kinase activity. The activities of the Erks were constitutively elevated in both v-raf- and v-abl-transformed cells. In both cell types the activities of Raf-1 and v-raf were almost completely suppressed after activation of the cyclic AMP-dependent kinase (protein kinase A [PKA]), whereas the v-abl kinase was not affected. Raf inhibition substantially diminished the activities of Erks in v-raf-transformed cells but not in v-abl-transformed cells, indicating that v-abl can activate Erks by a Raf-1-independent pathway. PKA activation induced apoptosis in v-abl-transformed cells while reverting v-raf transformation without severe cytopathic effects. Overexpression of Raf-1 in v-abl-transformed cells partially protected the cells from apoptosis induced by PKA activation. In contrast to PKA activators, a Mek inhibitor did not induce apoptosis. The diverse biological responses correlated with the status of c-myc gene expression. v-abl-transformed cells featured high constitutive levels of expression of c-myc, which were not reduced following PKA activation. Myc activation has been previously shown to be essential for transformation by oncogenic Abl proteins. Using estrogen-regulated c-myc and temperature-sensitive Raf-1 mutants, we found that Raf-1 activation could protect cells from c-myc-induced apoptosis. In conclusion, these results suggest (i) that Raf-1 participates in v-abl transformation via an Erk-independent pathway by providing a survival signal which complements c-myc in transformation, and (ii) that cAMP agonists might become useful for the treatment of malignancies where abl oncogenes are involved, such as chronic myeloid leukemias. PMID:9154822

  3. Effect of Electrical Stimulation on Beta-Adrenergic Receptor Population and Cyclic AMP Production in Chicken and Rat Skeletal Muscle Cell Cultures

    NASA Technical Reports Server (NTRS)

    Young, Ronald B.; Bridge, Kristin Y.; Strietzel, Catherine J.

    2000-01-01

    Expression of the beta-adrenergic receptor (PAR) and its coupling to Adenosine 3'5' Cyclic Monophosphate (cAMP) synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy and the goal of this study was to determine if electrical stimulation in a pattern simulating slow muscle contraction would alter the PAR response in primary cultures of avian and mammalian skeletal muscle cells. Specifically chicken skeletal muscle cells and rat skeletal muscle cells that had been grown for 7 d in culture, were subjected to electrical stimulation for an additional 2 d at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. In chicken skeletal muscle cells, the PAR population was not significantly affected by electrical stimulation; however, the ability, of these cells to synthesize cyclic AMP was reduced by approximately one-half. In contrast, the PAR population in rat muscle cells was increased slightly but not significantly by electrical stimulation, and the ability of these cells to synthesize cyclic AMP was increased by almost twofold. The basal levels of intracellular cyclic AMP in neither rat muscle cells nor chicken muscle cells were affected by electrical stimulation.

  4. Effects of human chorionic gonadotropin, prostaglandin F2 alpha and protein kinase C activators on the cyclic AMP and inositol phosphate second messenger systems in cultured human granulosa-luteal cells.

    PubMed

    Davis, J S; Tedesco, T A; West, L A; Maroulis, G B; Weakland, L L

    1989-08-01

    The effects of human chorionic gonadotropin (hCG) and prostaglandin F2 alpha (PGF2 alpha) on the adenylate cyclase-cAMP and inositol phospholipid-phospholipase C-inositol trisphosphate and diacylglycerol transmembrane signalling systems were evaluated in cultured human granulosa-luteal cells. Granulosa-luteal cells obtained from patients undergoing in vitro fertilization were cultured for 72 h prior to addition of hormones. During the last 24 h of culture granulosa-luteal cells were incubated with [3H]inositol. Neither hCG nor gonadotropin-releasing hormone (GnRH) stimulated the inositol phospholipid-phospholipase C signalling system. PGF2 alpha stimulated increases in inositol mono-, bis-, and trisphosphate accumulation in 30 min incubations. NaF (20 mM) mimicked the stimulatory effect of PGF2 alpha on inositol phosphate accumulation suggesting the involvement of a guanine nucleotide regulatory protein in the activation of phospholipase C. In contrast, hCG but not PGF2 alpha or NaF stimulated cAMP accumulation in 30 min incubations. Simultaneous treatment with hCG and PGF2 alpha did not alter the stimulatory effect of PGF2 alpha on inositol phosphate accumulation but reduced (37%) the stimulatory effect of hCG on cAMP accumulation. The protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (TPA) inhibited the stimulatory effects of hCG (76%) and PGF2 alpha (62%) on cAMP and inositol phosphate accumulation, respectively. Thus, cultures of human granulosa-luteal cells possess multiple transmembrane signalling systems which may be modulated by the activation of protein kinase C. PMID:2550298

  5. 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

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

    2010-01-01

    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. PMID:20887824

  6. Isolated horizontal cells from carp retina demonstrate dopamine-dependent accumulation of cyclic AMP.

    PubMed Central

    Van Buskirk, R; Dowling, J E

    1981-01-01

    Horizontal cells of the carp retina were separated from other retinal cell types by using enzymatic dissociation and velocity sedimentation at unit gravity. Fractions containing horizontal cells were tested for their ability to accumulate cyclic AMP in the presence of various putative neurotransmitters. Micromolar concentrations of dopamine, when added in the presence of 3-isobutyl-1-methylxanthine, stimulated cyclic AMP accumulation in these isolated cells. The dopamine-dependent accumulation of cyclic AMP in intact isolated horizontal cells was blocked by nanomolar concentrations of dopamine antagonists such as haloperidol, (+)-butaclamol, and fluphenazine. The results indicate that there is a postsynaptic dopamine receptor on carp horizontal cells that is associated with adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1]. Images PMID:6278491

  7. Cyclic AMP (cAMP)-Mediated Stimulation of Adipocyte Differentiation Requires the Synergistic Action of Epac- and cAMP-Dependent Protein Kinase-Dependent Processes?

    PubMed Central

    Petersen, Rasmus Koefoed; Madsen, Lise; Pedersen, Lone Møller; Hallenborg, Philip; Hagland, Hanne; Viste, Kristin; Døskeland, Stein Ove; Kristiansen, Karsten

    2008-01-01

    Cyclic AMP (cAMP)-dependent processes are pivotal during the early stages of adipocyte differentiation. We show that exchange protein directly activated by cAMP (Epac), which functions as a guanine nucleotide exchange factor for the Ras-like GTPases Rap1 and Rap2, was required for cAMP-dependent stimulation of adipocyte differentiation. Epac, working via Rap, acted synergistically with cAMP-dependent protein kinase (protein kinase A [PKA]) to promote adipogenesis. The major role of PKA was to down-regulate Rho and Rho-kinase activity, rather than to enhance CREB phosphorylation. Suppression of Rho-kinase impaired proadipogenic insulin/insulin-like growth factor 1 signaling, which was restored by activation of Epac. This interplay between PKA and Epac-mediated processes not only provides novel insight into the initiation and tuning of adipocyte differentiation, but also demonstrates a new mechanism of cAMP signaling whereby cAMP uses both PKA and Epac to achieve an appropriate cellular response. PMID:18391018

  8. Blocking CXCR4-mediated cyclic AMP suppression inhibits brain tumor growth in vivo.

    PubMed

    Yang, Lihua; Jackson, Erin; Woerner, B Mark; Perry, Arie; Piwnica-Worms, David; Rubin, Joshua B

    2007-01-15

    The chemokine CXCL12 and its cognate receptor CXCR4 regulate malignant brain tumor growth and are potential chemotherapeutic targets. However, the molecular basis for CXCL12-induced tumor growth remains unclear, and the optimal approach to inhibiting CXCR4 function in cancer is unknown. To develop such a therapeutic approach, we investigated the signaling pathways critical for CXCL12 function in normal and malignant cells. We discovered that CXCL12-dependent tumor growth is dependent upon sustained inhibition of cyclic AMP (cAMP) production, and that the antitumor activity of the specific CXCR4 antagonist AMD 3465 is associated with blocking cAMP suppression. Consistent with these findings, we show that pharmacologic elevation of cAMP with the phosphodiesterase inhibitor Rolipram suppresses tumor cell growth in vitro and, upon oral administration, inhibits intracranial growth in xenograft models of malignant brain tumors with comparable efficacy to AMD 3465. These data indicate that the clinical evaluation of phosphodiesterase inhibitors in the treatment of patients with brain tumors is warranted. PMID:17234775

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

    PubMed Central

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

    2013-01-01

    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

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

    PubMed

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

    1981-01-01

    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

  11. Cyclic AMP Receptor Protein Regulates cspD, a Bacterial Toxin Gene, in Escherichia coli

    PubMed Central

    Shetty, Deeksha M.; Jawali, Narendra

    2014-01-01

    cspD, a member of cspA family of cold shock genes in Escherichia coli, is not induced during cold shock. Its expression is induced during stationary phase. CspD inhibits DNA replication, and a high level of the protein is toxic to cells. Recently, CspD was proposed to be associated with persister cell formation in E. coli. Here, we show that cyclic AMP receptor protein (CRP) upregulates cspD transcription. Sequence analysis of the cspD upstream region revealed two tandem CRP target sites, CRP site-I (the proximal site centered at ?83.5 with respect to the transcription start) and CRP site-II (the distal site centered at ?112.5). The results from electrophoretic mobility shift assays showed that CRP indeed binds to these two target sites in PcspD. The promoter-proximal CRP target site was found to play a major role in PcspD activation by CRP, as studied by transcriptional fusions carrying mutations in the target sites. The results from in vitro transcription assays demonstrated that CRP activates PcspD transcription in the absence of additional factors other than RNA polymerase. The requirement for activating region 1 of CRP in PcspD activation, along with the involvement of the 287, 265, and 261 determinants of the ?-CTD, suggest that CRP activates by a class I-type mechanism. However, only moderate activation in vitro was observed compared to high activation in vivo, suggesting there might be additional activators of PcspD. Overall, our findings show that CRP, a global metabolic regulator in E. coli, activates a gene potentially related to persistence. PMID:24509317

  12. Cyclic AMP receptor protein regulates cspD, a bacterial toxin gene, in Escherichia coli.

    PubMed

    Uppal, Sheetal; Shetty, Deeksha M; Jawali, Narendra

    2014-04-01

    cspD, a member of cspA family of cold shock genes in Escherichia coli, is not induced during cold shock. Its expression is induced during stationary phase. CspD inhibits DNA replication, and a high level of the protein is toxic to cells. Recently, CspD was proposed to be associated with persister cell formation in E. coli. Here, we show that cyclic AMP receptor protein (CRP) upregulates cspD transcription. Sequence analysis of the cspD upstream region revealed two tandem CRP target sites, CRP site-I (the proximal site centered at -83.5 with respect to the transcription start) and CRP site-II (the distal site centered at -112.5). The results from electrophoretic mobility shift assays showed that CRP indeed binds to these two target sites in PcspD. The promoter-proximal CRP target site was found to play a major role in PcspD activation by CRP, as studied by transcriptional fusions carrying mutations in the target sites. The results from in vitro transcription assays demonstrated that CRP activates PcspD transcription in the absence of additional factors other than RNA polymerase. The requirement for activating region 1 of CRP in PcspD activation, along with the involvement of the 287, 265, and 261 determinants of the ?-CTD, suggest that CRP activates by a class I-type mechanism. However, only moderate activation in vitro was observed compared to high activation in vivo, suggesting there might be additional activators of PcspD. Overall, our findings show that CRP, a global metabolic regulator in E. coli, activates a gene potentially related to persistence. PMID:24509317

  13. Opposing roles of cyclic AMP in the vascular control of edema formation

    Microsoft Academic Search

    JOHN B. WARREN; J. WILSON; RASHPAL K. LOl; MARGARET L COUGHLAN

    Eight agents that increase the intracellu- lar concentration of cyclic AMP were tested for their effect on edema formation. The specificity of the agents for vascular smooth muscle or the endothelium was deter- mined by measuring vasodilation with a laser Doppler flow probe and cAMP production by endothelial cells and vascular smooth muscle cells in culture. The agents were injected

  14. The Cyclic AMP Cascade Is Altered in the Fragile X Nervous System

    E-print Network

    Wisconsin at Madison, University of

    of Wisconsin, Madison, Wisconsin, United States of America Fragile X syndrome (FX), the most common heritable INTRODUCTION Fragile X syndrome (FX) is characterized by physical, cognitive, and behavioral deficits [1The Cyclic AMP Cascade Is Altered in the Fragile X Nervous System Daniel J. Kelley1,2,3 , Richard J

  15. Regulation of cyclic AMP phosphodiesterase from human lung tissue by nucleosides and nucleotides 

    E-print Network

    Glass, William Fredrick

    1978-01-01

    to adenosine by the addition of 100pl of snake venom (Crotalus adamanteus, lmg/ml) which contains a 5'-nucleotidase. After 15-20 min Bio-Rad AG1-X2 anion exchange resin was added to separate the cyclic AMP from the adenosine. After 10 min (with occasional...

  16. Glucocorticoid Receptor, C/EBP, HNF3, and Protein Kinase A Coordinately Activate the Glucocorticoid Response Unit of the Carbamoylphosphate Synthetase I Gene

    PubMed Central

    Christoffels, Vincent M.; Grange, Thierry; Kaestner, Klaus H.; Cole, Timothy J.; Darlington, Gretchen J.; Croniger, Colleen M.; Lamers, Wouter H.

    1998-01-01

    A single far-upstream enhancer is sufficient to confer hepatocyte-specific, glucocorticoid- and cyclic AMP-inducible periportal expression to the carbamoylphosphate synthetase I (CPS) gene. To identify the mechanism of hormone-dependent activation, the composition and function of the enhancer have been analyzed. DNase I protection and gel mobility shift assays revealed the presence of a cyclic AMP response element, a glucocorticoid response element (GRE), and several sites for the liver-enriched transcription factor families HNF3 and C/EBP. The in vivo relevance of the transcription factors interacting with the enhancer in the regulation of CPS expression in the liver was assessed by the analysis of knockout mice. A strong reduction of CPS mRNA levels was observed in glucocorticoid receptor- and C/EBP?-deficient mice, whereas the CPS mRNA was normally expressed in C/EBP? knockout mice and in HNF3? and -? double-knockout mice. (The role of HNF? could not be assessed, because the corresponding knockout mice die at embryonic day 10). In hepatoma cells, most of the activity of the enhancer is contained within a 103-bp fragment, which depends for its activity on the simultaneous occupation of the GRE, HNF3, and C/EBP sites, thus meeting the requirement of a glucocorticoid response unit. In fibroblast-like CHO cells, on the other hand, the GRE in the CPS enhancer does not cooperate with the C/EBP and HNF3 elements in transactivation of the CPS promoter. In both hepatoma and CHO cells, stimulation of expression by cyclic AMP depends mainly on the integrity of the glucocorticoid pathway, demonstrating cross talk between this pathway and the cyclic AMP (protein kinase A) pathway. PMID:9774647

  17. Lindane decreases forskolin-stimulated cyclic AMP accumulation but does not modify Gs in rat enterocytes.

    PubMed

    Carrero, I; Rodríguez-Henche, N; Guijarro, L G; Recio, M N; Pèrez-Albarsanz, M A; Prieto, J C

    1993-07-01

    Treatment of isolated rat enterocytes with the halogenated insecticide lindane (the gamma-isomer of hexachlorocyclohexane, HCCH) did not modify the general membrane fluidity (as estimated by a fluorescence polarization technique) nor the guanine nucleotide binding regulatory protein Gs (as studied by both ADP-ribosylation of its alpha subunit by cholera toxin and Gpp[NH]p stimulation of membrane adenylate cyclase activity). However, lindane decreased in a dose-dependent manner the effect of the diterpene forskolin on direct activation of the adenylate cyclase catalytic subunit. After 5 min of cell treatment with 0.5 mM lindane, the maximal stimulatory effect of forskolin (at 100 microM) decreased by about 50%. There was a certain degree of specificity since delta-HCCH was indeed more potent, whereas dieldrin and endrin (non-lindane related halogenated compounds) behaved as lindane, and alpha- and beta-HCCH were poorly efficient on the inhibition of forskolin stimulation of adenylate cyclase activity. A similar effect of lindane was observed on receptor-stimulated cyclic AMP accumulation by using vasoactive intestinal peptide instead of forskolin. The results on a non-receptor mediated effect of lindane on the adenylate cyclase catalytic subunit itself could be related to: (i) alterations of membrane microdomains surrounding this and other integral proteins which would result in modifications of their activities; and/or (ii) a reciprocal relation between the two main routes of signal transduction so that the activation of protein kinase C (or other Ca(2+)-dependent protein kinases) by lindane would lead to phosphorylation of the adenylate cyclase catalytic subunit.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7690584

  18. Rab11, but not Rab4, facilitates cyclic AMP- and tauroursodeoxycholate-induced MRP2 translocation to the plasma membrane.

    PubMed

    Park, Se Won; Schonhoff, Christopher M; Webster, Cynthia R L; Anwer, M Sawkat

    2014-10-15

    Rab proteins (Ras homologous for brain) play an important role in vesicle trafficking. Rab4 and Rab11 are involved in vesicular trafficking to the plasma membrane from early endosomes and recycling endosomes, respectively. Tauroursodeoxycholate (TUDC) and cAMP increase bile formation, in part, by increasing plasma membrane localization of multidrug resistance-associated protein 2 (MRP2). The goal of the present study was to determine the role of these Rab proteins in the trafficking of MRP2 by testing the hypothesis that Rab11 and/or Rab4 facilitate cAMP- and TUDC-induced MRP2 translocation to the plasma membrane. Studies were conducted in HuH-NTCP cells (HuH7 cells stably transfected with human NTCP), which constitutively express MRP2. HuH-NTCP cells were transfected with Rab11-WT and GDP-locked dominant inactive Rab11-GDP or with Rab4-GDP to study the role of Rab11 and Rab4. A biotinylation method and a GTP overlay assay were used to determine plasma membrane MRP2 and activation of Rab proteins (Rab11 and Rab4), respectively. Cyclic AMP and TUDC increased plasma membrane MRP2 and stimulated Rab11 activity. Plasma membrane translocation of MRP2 by cAMP and TUDC was increased and inhibited in cells transfected with Rab11-WT and Rab11-GDP, respectively. Cyclic AMP (previous study) and TUDC increased Rab4 activity. However, cAMP- and TUDC-induced increases in MRP2 were not inhibited by Rab4-GDP. Taken together, these results suggest that Rab11 is involved in cAMP- and TUDC-induced MRP2 translocation to the plasma membrane. PMID:25190474

  19. Regulatory Action of Calcium Ion on Cyclic AMP-Enhanced Expression of Implantation-Related Factors in Human Endometrial Cells

    PubMed Central

    Kusama, Kazuya; Yoshie, Mikihiro; Tamura, Kazuhiro; Imakawa, Kazuhiko; Isaka, Keiichi; Tachikawa, Eiichi

    2015-01-01

    Decidualization of human endometrial stroma and gland development is mediated through cyclic AMP (cAMP), but the role of intracellular calcium ion (Ca2+) on cAMP mediated-signaling in human endometrial stroma and glandular epithelia has not been well-characterized. The present study was designed to investigate the role of intracellular Ca2+ on cAMP mediated-decidualization and gland maturation events, which can be identified by the up-regulation of prolactin and IGF-binding protein (IGFBP)1 in human endometrial stromal cells (ESCs), and cyclooxygenase 2 (COX2) and prostaglandin E2 (PGE2) and glandular epithelial EM-1 cells. Increases in decidual prolactin and IGFBP-1 transcript levels, induced by cAMP-elevating agents forskolin or dibutyryl cyclic AMP, were inhibited by Ca2+ influx into ESCs with Ca2+ ionophores (alamethicin, ionomycin) in a dose-dependent manner. Conversely, inhibitors of Ca2+ influx through L-type voltage-dependent Ca2+ channel (VDCC), nifedipine and verapamil, enhanced the decidual gene expression. Furthermore, dantrolene, an inhibitor of Ca2+ release from the intracellular Ca2+ store, up-regulated prolactin and IGFBP-1 expression. Ca2+ ionophores decreased intracellular cAMP concentrations, whereas nifedipine, verapamil or dantrolene increased cAMP concentrations in ESCs. In glandular epithelial cells, similar responses in COX2 expression and PGE2 production were found when intracellular cAMP levels were up-regulated by decreases in Ca2+ concentrations. Thus, a marked decrease in cytosolic Ca2+ levels caused the elevation of cAMP concentrations, resulting in enhanced expression of implantation-related factors including decidual markers. These findings suggest that fluctuation in cytosolic Ca2+ concentrations alters intracellular cAMP levels, which then regulate differentiation of endometrial stromal and glandular epithelial cells. PMID:26161798

  20. Glucagon, cyclic AMP and adrenaline stimulate the degradation of low-density lipoprotein by cultured rat hepatocytes.

    PubMed Central

    Brown, N F; Salter, A M; Fears, R; Brindley, D N

    1989-01-01

    Rat hepatocytes were preincubated for 16 h with hormones or drugs and then for a further 8 h with 125I-human low-density lipoprotein (LDL). Glucagon (via cyclic AMP) and adrenaline (via cyclic AMP and alpha-effects) increased the binding of 125I-LDL to the LDL receptor, and the degradation of LDL to [125I]iodotyrosine. The effects on degradation were antagonized by dexamethasone, and the action of cyclic AMP on binding and degradation was inhibited by actinomycin D. The results are discussed in relation to the control of lipoprotein metabolism in diabetes. PMID:2552996

  1. Acute morphine alters GABAergic transmission in the central amygdala during naloxone-precipitated morphine withdrawal: role of cyclic AMP

    PubMed Central

    Bajo, Michal; Madamba, Samuel G.; Roberto, Marisa; Siggins, George R.

    2014-01-01

    The central amygdala (CeA) plays an important role in opioid addiction. Therefore, we examined the effects of naloxone-precipitated morphine withdrawal (WD) on GABAergic transmission in rat CeA neurons using whole-cell recordings with naloxone in the bath. The basal frequency of miniature inhibitory postsynaptic currents (mIPSCs) increased in CeA neurons from WD compared to placebo rats. Acute morphine (10 ? M) had mixed effects (?20% change from baseline) on mIPSCs in placebo and WD rats. In most CeA neurons (64%) from placebo rats, morphine significantly decreased mIPSC frequency and amplitude. In 32% of placebo neurons, morphine significantly increased mIPSC amplitudes but had no effect on mIPSC frequency. In WD rats, acute morphine significantly increased mIPSC frequency but had no effect on mIPSC amplitude in 41% of CeA neurons. In 45% of cells, acute morphine significantly decreased mIPSC frequency and amplitude. Pre-treatment with the cyclic AMP inhibitor (R)-adenosine, cyclic 3',5'-(hydrogenphosphorothioate) triethylammonium (RP), prevented acute morphine-induced potentiation of mIPSCs. Pre-treatment of slices with the Gi/o G-protein subunit inhibitor pertussis toxin (PTX) did not prevent the acute morphine-induced enhancement or inhibition of mIPSCs. PTX and RP decreased basal mIPSC frequencies and amplitudes only in WD rats. The results suggest that inhibition of GABAergic transmission in the CeA by acute morphine is mediated by PTX-insensitive mechanisms, although PTX-sensitive mechanisms cannot be ruled out for non-morphine responsive cells; by contrast, potentiation of GABAergic transmission is mediated by activated cAMP signaling that also mediates the increased basal GABAergic transmission in WD rats. Our data indicate that during the acute phase of WD, the CeA opioid and GABAergic systems undergo neuroadaptative changes conditioned by a previous chronic morphine exposure and dependence. PMID:24926240

  2. Luteinizing hormone stimulates the formation of inositol trisphosphate and cyclic AMP in rat granulosa cells. Evidence for phospholipase C generated second messengers in the action of luteinizing hormone.

    PubMed

    Davis, J S; Weakland, L L; West, L A; Farese, R V

    1986-09-01

    The following studies were conducted to determine whether luteinizing hormone (LH), a hormone which increases cellular levels of cyclic AMP, also provokes increases in 'second messengers' derived from inositol lipid metabolism (i.e. inositol phosphates and diacylglycerol). Rat granulosa cells isolated from mature Graafian follicles were prelabelled for 3 h with myo-[2-3H]inositol. LH provoked rapid (5 min) and sustained (up to 60 min) increases in the levels of inositol mono-, bis, and trisphosphates (IP, IP2 and IP3, respectively). Time course studies revealed that IP3 was formed more rapidly than IP2 and IP following LH treatment. The response to LH was concentration-dependent with maximal increases at LH concentrations of 1 microgram/ml. LiCl (2-40 mM) enhanced the LH-provoked accumulation of all [3H]inositol phosphates, presumably by inhibiting the action of inositol phosphate phosphatases. The effectiveness of LH, however, was dependent on the concentration of lithium employed; maximal increases in IP were observed at 10 mM-LiCl, whereas maximal increases in IP2 and IP3 were observed at 20 mM- and 40 mM-LiCl, respectively. The stimulatory effects of LH on inositol phosphate and progesterone accumulation were also compared with changes in cyclic nucleotide levels. LH rapidly increased levels of inositol phosphates, progesterone and cyclic AMP, but transiently reduced levels of cyclic GMP. These results demonstrate that LH increases both cyclic AMP and inositol trisphosphate (and presumably diacylglycerol) in rat granulosa cells. Our findings suggest that two messenger systems exist to mediate the action of LH in granulosa cells. PMID:3026357

  3. Luteinizing hormone stimulates the formation of inositol trisphosphate and cyclic AMP in rat granulosa cells. Evidence for phospholipase C generated second messengers in the action of luteinizing hormone.

    PubMed Central

    Davis, J S; Weakland, L L; West, L A; Farese, R V

    1986-01-01

    The following studies were conducted to determine whether luteinizing hormone (LH), a hormone which increases cellular levels of cyclic AMP, also provokes increases in 'second messengers' derived from inositol lipid metabolism (i.e. inositol phosphates and diacylglycerol). Rat granulosa cells isolated from mature Graafian follicles were prelabelled for 3 h with myo-[2-3H]inositol. LH provoked rapid (5 min) and sustained (up to 60 min) increases in the levels of inositol mono-, bis, and trisphosphates (IP, IP2 and IP3, respectively). Time course studies revealed that IP3 was formed more rapidly than IP2 and IP following LH treatment. The response to LH was concentration-dependent with maximal increases at LH concentrations of 1 microgram/ml. LiCl (2-40 mM) enhanced the LH-provoked accumulation of all [3H]inositol phosphates, presumably by inhibiting the action of inositol phosphate phosphatases. The effectiveness of LH, however, was dependent on the concentration of lithium employed; maximal increases in IP were observed at 10 mM-LiCl, whereas maximal increases in IP2 and IP3 were observed at 20 mM- and 40 mM-LiCl, respectively. The stimulatory effects of LH on inositol phosphate and progesterone accumulation were also compared with changes in cyclic nucleotide levels. LH rapidly increased levels of inositol phosphates, progesterone and cyclic AMP, but transiently reduced levels of cyclic GMP. These results demonstrate that LH increases both cyclic AMP and inositol trisphosphate (and presumably diacylglycerol) in rat granulosa cells. Our findings suggest that two messenger systems exist to mediate the action of LH in granulosa cells. PMID:3026357

  4. Cyclic AMP-receptor proteins in heart muscle of rats flown on Cosmos 1887

    NASA Technical Reports Server (NTRS)

    Mednieks, Maija I.; Popova, Irina A.; Grindeland, Richard E.

    1991-01-01

    The cellular compartmentalization of the cyclic AMP-receptor proteins in heart ventricular tissue obtained from rats flown on the Cosmos 1887 is determined. Photoaffinity labeling of soluble and particular cell fractions with a (32P)-8-azido analog of cyclic AMP is followed by electrophoretic separation of the proteins and by autoradiographic identification of the labeled isoforms of cAPK R subunits. It is shown that RII in the particulate subcellular fraction was significantly decreased in heart cells from rats in the flight group when compared to controls. Protein banding patterns in both the cytoplasmic fraction and in a fraction enriched in chromatin-bound proteins exhibited some variability in tissues of individual animals, but showed no changes that could be directly attributed to flight conditions. No significant change was apparent in the distribution of RI or RII cyclic AMP binding in the soluble fractions. It is inferred that the cardiac cell integrity or its protein content is not compromised under flight conditions.

  5. Light-induced photoreceptor shedding in teleost retina blocked by dibutyryl cyclic AMP.

    PubMed

    Eckmiller, M S; Burnside, B

    1983-09-01

    In retinas of lower vertebrates, at least two retinal phenomena appear to be closely tied to the diurnal light-dark cycle: photoreceptor renewal and retinomotor movements. The authors have previously reported that treatments that elevate retinal cyclic AMP levels induce dark-adaptive retinomotor movements. In the present study, the authors have tested whether cyclic nucleotides might also inhibit the burst of rod outer segment shedding expected to occur shortly following light onset. Green sunfish (Lepomis cyanellus) entrained to a 12hL:12hD schedule were given intraocular injections 1 hr before the time of light onset and killed 1 hr after light onset. Epon sections of retinas were used for RPE phagosome counts and for measurements of photoreceptor and RPE retinomotor positions. It is reported that injection of the cyclic AMP analog dibutyryl cyclic AMP before light onset (1) completely blocked the light-induced burst of photoreceptor shedding seen at dawn in these fish; and (2) inhibited light-adaptive retinomotor movements in the pigment epithelium but not in photoreceptors. PMID:6309697

  6. Cyclic AMP-Stimulated Interaction between Steroidogenic Factor 1 and Diacylglycerol Kinase ? Facilitates Induction of CYP17?

    PubMed Central

    Li, Donghui; Urs, Aarti N.; Allegood, Jeremy; Leon, Adam; Merrill, Alfred H.; Sewer, Marion B.

    2007-01-01

    In the human adrenal cortex, adrenocorticotropin (ACTH) activates CYP17 transcription by promoting the binding of the nuclear receptor steroidogenic factor 1 (SF1) (Ad4BP, NR5A1) to the promoter. We recently found that sphingosine is an antagonist for SF1 and inhibits cyclic AMP (cAMP)-dependent CYP17 gene transcription. The aim of the current study was to identify phospholipids that bind to SF1 and to characterize the mechanism by which ACTH/cAMP regulates the biosynthesis of this molecule(s). Using tandem mass spectrometry, we show that in H295R human adrenocortical cells, SF1 is bound to phosphatidic acid (PA). Activation of the ACTH/cAMP signal transduction cascade rapidly increases nuclear diacylglycerol kinase (DGK) activity and PA production. PA stimulates SF1-dependent transcription of CYP17 reporter plasmids, promotes coactivator recruitment, and induces the mRNA expression of CYP17 and several other steroidogenic genes. Inhibition of DGK activity attenuates the binding of SF1 to the CYP17 promoter, and silencing of DGK-? expression inhibits cAMP-dependent CYP17 transcription. LXXLL motifs in DGK-? mediate a direct interaction of SF1 with the kinase and may facilitate binding of PA to the receptor. We conclude that ACTH/cAMP stimulates PA production in the nucleus of H295R cells and that this increase in PA concentrations facilitates CYP17 induction. PMID:17664281

  7. Cyclic AMP Phosphodiesterase4 in Brain Tumor Biology: Immunochemical Analysis

    Microsoft Academic Search

    B. Mark Woerner; Joshua B. Rubin

    \\u000a Central to advancing the care for patients with malignant neoplasms are efforts to delineate how cancer cells differ from\\u000a their normal counterparts, and the identification of biological targets whose activity, when normalized, corrects the cancer\\u000a phenotype and re-establishes normal growth control. In this regard we and others have described the tumor promoting actions\\u000a of cyclic adenosine monophos­phate (cAMP) phosphodiesterases and

  8. Store-operated cyclic AMP signalling mediated by STIM1

    Microsoft Academic Search

    Konstantinos Lefkimmiatis; Meera Srikanthan; Isabella Maiellaro; Mary Pat Moyer; Silvana Curci; Aldebaran M. Hofer

    2009-01-01

    Depletion of Ca2+ from the endoplasmic reticulum (ER) results in activation of plasma membrane Ca2+ entry channels. This 'store-operated' process requires translocation of a transmembrane ER Ca2+ sensor protein, stromal interaction molecule 1 (STIM1), to sites closely apposed to Ca2+ channels at the cell surface. However, it is not known whether a reduction in Ca2+ stores is coupled to other

  9. Involvement of Cyclic AMP Receptor Protein in Regulation of the rmf Gene Encoding the Ribosome Modulation Factor in Escherichia coli

    PubMed Central

    Shimada, Tomohiro; Yoshida, Hideji

    2013-01-01

    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

  10. Uptake and Degradation of Cyclic AMP by Chloronema Cells

    PubMed Central

    Sharma, Shobhona; Johri, Man Mohan

    1982-01-01

    Suspension cultures of intact chloronema cells of the moss Funaria hygrometrica take up [3H]cAMP and degrade it rapidly. The increase in total radioactivity accumulated by the cells was linear up to 30 minutes. Initially, the major degradation products were 5?-AMP and adenosine, but later predominantly ADP and ATP. In spite of rapid degradation, the amount of extracellularly applied cAMP retained by the cells is about 4-fold higher than the maximum endogenous level of cAMP reported previously (Handa, Johri 1977 Plant Physiol 59: 490-496). The uptake showed a distinct dependence on the density of the culture. Cells at a lower cell density (1-2 milligrams per milliliter) accumulated 4 to 6 times more radioactivity than the cells at high density (>10 milligrams per milliliter). The cyclic nucleotide phosphodiesterase (cNPDE) activity of whole cells (18 milliunits per milligram protein) was comparable to that of protoplasts (23 milliunits per milligram protein), but about 4-fold lower than that of lysed protoplasts (80 milliunits per milligram protein), indicating an intracellular degradation of cAMP by chloronema cells. Images PMID:16662411

  11. Inhibition by amphetamine of testosterone secretion through a mechanism involving an increase of cyclic AMP production in rat testes.

    PubMed Central

    Tsai, S. C.; Chiao, Y. C.; Lu, C. C.; Doong, M. L.; Chen, Y. H.; Shih, H. C.; Liaw, C.; Wang, S. W.; Wang, P. S.

    1996-01-01

    1. The effect of amphetamine on the secretion of testosterone and the production of testicular adenosine 3':5'-cyclic monophosphate (cyclic AMP) in rats was studied. 2. A single intravenous injection of amphetamine decreased the basal and human chorionic gonadotropin (hCG)-stimulated levels of plasma testosterone. Plasma LH levels were not altered by the injection of amphetamine. 3. Administration of amphetamine in vitro resulted in a dose-dependent inhibition of both basal and hCG-stimulated release of testosterone. 4. Amphetamine enhanced the basal and hCG-increased levels of cyclic AMP accumulation in vitro in rat testes. 5. These results suggest that amphetamine inhibits the spontaneous and hCG-stimulated secretion of testosterone from the testes through a mechanism involving an increase in cyclic AMP production. PMID:8799572

  12. Adenylyl cyclase-cyclicAMP signaling in mood disorders: Role of the crucial phosphorylating enzyme protein kinase A

    PubMed Central

    Dwivedi, Yogesh; Pandey, Ghanshyam N

    2008-01-01

    Mood disorders are among the most prevalent and recurrent forms of psychiatric illnesses. In the last decade, there has been increased understanding of the biological basis of mood disorders. In fact, novel mechanistic concepts of the neurobiology of unipolar and bipolar disorders are evolving based on recent pre-clinical and clinical studies, most of which now focus on the role of signal transduction mechanisms in these psychiatric illnesses. Particular investigative emphasis has been given to the role of phosphorylating enzymes, which are crucial in regulating gene expression and neuronal and synaptic plasticity. Among the most important phosphorylating enzyme is protein kinase A (PKA), a component of adenylyl cyclase–cyclic adenosine monophosphate (AC–cAMP) signaling system. In this review, we critically and comprehensively discuss the role of various components of AC–cAMP signaling in mood disorders, with a special focus on PKA, because of the interesting observation that have been made about its involvement in unipolar and bipolar disorders. We also discuss the functional significance of the findings regarding PKA by discussing the role of important PKA substrates, namely, Rap-1, cyclicAMP-response element binding protein, and brain-derived neurotrophic factor. These studies suggest the interesting possibility that PKA and related signaling molecules may serve as important neurobiological factors in mood disorders and may be relevant in target-specific therapeutic interventions for these disorders. PMID:18728821

  13. Cyclic AMP counteracts mitogen-induced inositol phosphate generation and increases in intracellular Ca2+ concentrations in human lymphocytes.

    PubMed Central

    van Tits, L. J.; Michel, M. C.; Motulsky, H. J.; Maisel, A. S.; Brodde, O. E.

    1991-01-01

    1. The effects of increases in intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP) on mitogen-induced generation of inositol phosphates and increases in intracellular Ca2+ concentration were investigated in human peripheral blood mononuclear leukocytes (MNL). 2. The mitogens concanavalin A (Con A), pokeweed mitogen (PWM) and phytohaemagglutinin (PHA) concentration-dependently stimulated generation of inositol phosphates. Catecholamines inhibited this process with an order of potency: isoprenaline greater than adrenaline greater than noradrenaline indicating involvement of beta 2-adrenoceptors. This order of potency was also consistent with the catecholamine potencies for stimulating the generation of cyclic AMP. 3. In addition to catecholamines, the cyclic AMP formation-stimulating agents prostaglandin E1 (PGE1) and forskolin concentration-dependently inhibited mitogen-induced inositol phosphate generation, too. Moreover, the inhibitory effect of isoprenaline was potentiated by co-incubation with the phosphodiesterase inhibitor isobutylmethylxanthine demonstrating that these inhibitory effects were mediated by cyclic AMP. 4. Con A and PHA concentration-dependently increased the intracellular Ca2+ concentration in human MNL (assessed by the fluorescent indicator dye Fura-2). This increase was almost completely blocked by chelation of extracellular Ca2+, demonstrating influx rather than mobilization from intracellular stores. 5. The elevation of intracellular Ca2+ was not blocked by pretreatment with pertussis toxin, 100 ng ml-1, for 16 h. 6. Isoprenaline, PGE1, and forskolin, however, inhibited the mitogen-stimulated elevation of intracellular Ca2+. This inhibition was enhanced by the phosphodiesterase inhibitors isobutylmethylxanthine and Ro 20-1724, demonstrating mediation by cyclic AMP. 7. We conclude that catecholamines and other cyclic AMP increasing agents can inhibit mitogen-stimulated generation of inositol phosphates and elevation of intracellular Ca2+ in resting human MNL.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1653068

  14. Seventeen Sxy-Dependent Cyclic AMP Receptor Protein Site-Regulated Genes Are Needed for Natural Transformation in Haemophilus influenzae

    PubMed Central

    Mell, Joshua C.; Redfield, Rosemary J.

    2012-01-01

    Natural competence is the ability of bacteria to actively take up extracellular DNA. This DNA can recombine with the host chromosome, transforming the host cell and altering its genotype. In Haemophilus influenzae, natural competence is induced by energy starvation and the depletion of nucleotide pools. This induces a 26-gene competence regulon (Sxy-dependent cyclic AMP receptor protein [CRP-S] regulon) whose expression is controlled by two regulators, CRP and Sxy. The role of most of the CRP-S genes in DNA uptake and transformation is not known. We have therefore created in-frame deletions of each CRP-S gene and studied their competence phenotypes. All but one gene (ssb) could be deleted. Although none of the remaining CRP-S genes were required for growth in rich medium or survival under starvation conditions, DNA uptake and transformation were abolished or reduced in most of the mutants. Seventeen genes were absolutely required for transformation, with 14 of these genes being specifically required for the assembly and function of the type IV pilus DNA uptake machinery. Only five genes were dispensable for both competence and transformation. This is the first competence regulon for which all genes have been mutationally characterized. PMID:22821979

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

    Microsoft Academic Search

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

    1993-01-01

    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 (a-adrenergic action) in a dose-dependent fashion. Increasing cyclic PIP synthesis with increasing insulin concentrations matches

  16. Novel Mechanism Coupling Cyclic AMP-Protein Kinase A Signaling and Golgi Trafficking via Gyp1 Phosphorylation in Polarized Growth

    PubMed Central

    Wang, Haitao; Wang, Yan-Ming

    2014-01-01

    The cyclic AMP (cAMP)-protein kinase A (PKA) signaling activates virulence expression during hyphal development in the fungal human pathogen Candida albicans. The hyphal growth is characterized by Golgi polarization toward the hyphal tips, which is thought to enhance directional vesicle transport. However, how the hypha-induction signal regulates Golgi polarization is unknown. Gyp1, a Golgi-associated protein and the first GTPase-activating protein (GAP) in the Rab GAP cascade, critically regulates membrane trafficking from the endoplasmic reticulum to the plasma membrane. Here, we report a novel pathway by which the cAMP-PKA signaling triggers Golgi polarization during hyphal growth. We demonstrate that Gyp1 plays a crucial role in actin-dependent Golgi polarization. Hyphal induction activates PKA, which in turn phosphorylates Gyp1. Phosphomimetic mutation of four PKA sites identified by mass spectrometry (Gyp14E) caused strong Gyp1 polarization to hyphal tips, whereas nonphosphorylatable mutations (Gyp14A) abolished it. Gyp14E exhibited enhanced association with the actin motor Myo2, while Gyp14A showed the opposite effect, providing a possible mechanism for Golgi polarization. A GAP-dead Gyp1 (Gyp1R292K) showed strong polarization similar to that seen with Gyp14E, indicating a role for the GAP activity. Mutating the PKA sites on Gyp1 also impaired the recruitment of a late Golgi marker, Sec7. Furthermore, proper PKA phosphorylation and GAP activity of Gyp1 are required for virulence in mice. We propose that the cAMP-PKA signaling directly targets Gyp1 to promote Golgi polarization in the yeast-to-hypha transition, an event crucial for C. albicans infection. PMID:25326521

  17. Alkaloid binding and activation of D2 dopamine receptors in cell culture.

    PubMed

    Larson, B T; Harmon, D L; Piper, E L; Griffis, L M; Bush, L P

    1999-04-01

    Ergot and pyrrolizidine alkaloids, either extracted from endophyte-infected tall fescue, synthesized, or purchased commercially, were evaluated in cultured cells to estimate their binding to the D2 dopamine receptor and subsequent effects on cyclic AMP production in GH4ZR7 cells, transfected with a rat D2 dopamine receptor. Ergopeptide alkaloid (alpha-ergocryptine, bromocryptine, ergotamine tartrate, and ergovaline) inhibition of the binding of the D2-specific radioligand, [3H]YM-09151-2, exhibited inhibition constants (K(I)) in the nanomolar range, whereas dopamine was less potent (micromolar). The lysergic acid amides (ergine and ergonovine) were 1/100th as potent as the ergopeptide alkaloids. Ergovaline and ergotamine tartrate were equally effective in inhibiting vasoactive intestinal peptide (VIP)-stimulated cyclic AMP production, with consistent nanomolar effective concentration (EC50) values. The remaining ergopeptide alkaloids (alpha-ergocryptine and bromocryptine), lysergic acid amides (ergonovine and ergine), and dopamine were 1/100th as potent. Two representative pyrrolizidines, N-formylloline and N-acetylloline, exhibited no binding activity at the D2 dopamine receptor or effects on the cyclic AMP system within the concentration ranges of nanomolar to millimolar. Our results indicate that the commercially available ergot alkaloids ergotamine tartrate and ergonovine may be used interchangeably in the D2 dopamine receptor system to simulate the effects of extracted ergovaline and ergine and to examine responses in receptor binding and the inhibition of cyclic AMP. PMID:10328360

  18. Cyclic AMP inhibits neuromuscular junction maturation mediated by intracellular Ca2+.

    PubMed

    Song, Wei; Jin, Xiwan Albert

    2015-03-01

    The neuromuscular junction (NMJ) is established through initial contact of motor neuron axon with a skeletal muscle cell and the subsequent synaptic maturation. Previous studies have shown that cyclic AMP (cAMP) enhanced spinal neurons' survival and growth but inhibited synaptogenesis. Here, we find that elevating intracellular cAMP level of presynaptic neurons prevented NMJs from maturation both physiologically and morphologically. Importantly, cytosolic Ca(2+) is essential for the inhibitory effects of cAMP on NMJ maturation. We show that depletion of intracellular Ca(2+) store, rather than extracellular Ca(2+), abolished the cAMP-dependent inhibition of synaptic maturation. Taken together, we demonstrate that Ca(2+) released from intracellular Ca(2+) stores regulates neurotrophic actions on NMJ maturation. PMID:25596442

  19. Specific effect of magnesium ion on 2', 3'-cyclic amp synthesis from adenosine and trimeta phosphate in aqueous solution

    NASA Astrophysics Data System (ADS)

    Yamagata, Y.; Inoue, H.; Inomata, K.

    1995-06-01

    Phosphorylation of adenosine by trimetaphosphate was investigated using various catalysts in aqueous solution under mild conditions at pH ˜ 7.0 and at 41 °C. The product was primarily 2',3'-cyclic AMP together with smaller amounts of ATP. Magnesium ion was found to have a remarkable catalytic effect of approximately one hundred times greater than the other chemicals tested. The mechanism for the specific effect of magnesium ion is discussed.

  20. GEMM-I riboswitches from Geobacter sense the bacterial second messenger cyclic AMP-GMP.

    PubMed

    Kellenberger, Colleen A; Wilson, Stephen C; Hickey, Scott F; Gonzalez, Tania L; Su, Yichi; Hallberg, Zachary F; Brewer, Thomas F; Iavarone, Anthony T; Carlson, Hans K; Hsieh, Yu-Fang; Hammond, Ming C

    2015-04-28

    Cyclic dinucleotides are an expanding class of signaling molecules that control many aspects of bacterial physiology. A synthase for cyclic AMP-GMP (cAG, also referenced as 3'-5', 3'-5' cGAMP) called DncV is associated with hyperinfectivity of Vibrio cholerae but has not been found in many bacteria, raising questions about the prevalence and function of cAG signaling. We have discovered that the environmental bacterium Geobacter sulfurreducens produces cAG and uses a subset of GEMM-I class riboswitches (GEMM-Ib, Genes for the Environment, Membranes, and Motility) as specific receptors for cAG. GEMM-Ib riboswitches regulate genes associated with extracellular electron transfer; thus cAG signaling may control aspects of bacterial electrophysiology. These findings expand the role of cAG beyond organisms that harbor DncV and beyond pathogenesis to microbial geochemistry, which is important to environmental remediation and microbial fuel cell development. Finally, we have developed an RNA-based fluorescent biosensor for live-cell imaging of cAG. This selective, genetically encodable biosensor will be useful to probe the biochemistry and cell biology of cAG signaling in diverse bacteria. PMID:25848022

  1. Cyclic AMP in oocytes controls meiotic prophase I and primordial folliculogenesis in the perinatal mouse ovary.

    PubMed

    Wang, Yijing; Teng, Zhen; Li, Ge; Mu, Xinyi; Wang, Zhengpin; Feng, Lizhao; Niu, Wanbao; Huang, Kun; Xiang, Xi; Wang, Chao; Zhang, Hua; Xia, Guoliang

    2015-01-15

    In mammalian ovaries, a fixed population of primordial follicles forms during the perinatal stage and the oocytes contained within are arrested at the dictyate stage of meiotic prophase I. In the current study, we provide evidence that the level of cyclic AMP (cAMP) in oocytes regulates oocyte meiotic prophase I and primordial folliculogenesis in the perinatal mouse ovary. Our results show that the early meiotic development of oocytes is closely correlated with increased levels of intra-oocyte cAMP. Inhibiting cAMP synthesis in fetal ovaries delayed oocyte meiotic progression and inhibited the disassembly and degradation of synaptonemal complex protein 1. In addition, inhibiting cAMP synthesis in in vitro cultured fetal ovaries prevented primordial follicle formation. Finally, using an in situ oocyte chromosome analysis approach, we found that the dictyate arrest of oocytes is essential for primordial follicle formation under physiological conditions. Taken together, these results suggest a role for cAMP in early meiotic development and primordial follicle formation in the mouse ovary. PMID:25503411

  2. Cyclic AMP restores a normal phenotype to sis oncogene transformed cells and inhibits inositol phospholipid turnover

    SciTech Connect

    Murphy, S.K.; Lazarus, A.; Pendergas, M.; Lockwood, A.H.

    1987-05-01

    The sis oncogene encodes the A chain of platelet-derived growth factor (PDGF). NIH3T3 fibroblasts transfected with the cloned sis oncogene display a malignant phenotype and have enhanced turnover of the regulatory phospholipid phosphatidylinositol 4,5 biphosphate (PIP2). They have found that elevation of intracellular cyclic AMP can restore many aspects of normal growth and morphology to sis-transformed cells. Cells rapidly become less refractile, flatten on the substratum, develop actomyosin bundles, and acquire a more tranquil membrane. Growth rate and saturation density are reduced. Cultures become contact-inhibited and, at confluence, assume a normal fibrobastic morphology. The ability to grow in low serum or suspension is lost. Following addition of 8-Br-cAMP, cellular levels of PIP and PIP2 increase to those in untransformed cells. Concurrently, the steady-state levels of inositol phosphates are reduced to normal values. They have found a similar effect of cAMP on inositol phospholipid metabolism in cells transformed by the human H-ras oncogene. These results suggest that cAMP, acting through the cAMP-dependent protein kinase, antagonizes ras and sis oncogene expression by inhibiting polyphosphoinositide turnover. Such action might occur by phosphorylation of the PDGF (sis) receptor or of a ras-stimulated phospholipase C.

  3. Changes in sodium, potassium-ATPase induced by repeated fencamfamine: the roles of cyclic AMP-dependent protein kinase and the nitric oxide-cyclic GMP pathway.

    PubMed

    Munhoz, Carolina Demarchi; Glezer, Isaias; Kawamoto, Elisa Mitiko; Araújo, Ana Paula Natalini; Lepscha, Lucília B; Planeta, Cleopatra S; DeLucia, Roberto; Scavone, Cristoforo

    2003-12-01

    Fencamfamine (FCF) is an indirect dopamine agent with effects similar to amphetamine and cocaine. In the present study, we investigate changes in Na,K-ATPase, cyclic AMP-dependent protein kinase (PKA) and nitric oxide synthase (NOS) activity and cyclic GMP levels in the nucleus accumbens (NAc) and striatum (ST) of animals acutely or repeatedly treated with FCF (3.5 mg/kg). Na,K-ATPase had a similar activity in control and repeatedly treated animals, but was reduced in the NAc of the acute group. This enzyme was reduced in the ST in acute and repeatedly treated animals, compared to the control group. Expression of the alpha(1,2,3)-Na,K-ATPase isoforms in the NAc and the ST was not altered in all groups studied. Acute FCF induced a significant increase in PKA activity in both the ST and the NAc. Repeatedly treated animals showed a higher increase in PKA activity in the NAc, but not in the ST, when compared to the acute group. There was also an increase in both NOS activity and cyclic GMP levels only in the NAc of FCF repeatedly treated animals compared to the acute and control groups. We suggest that chronic FCF treatment is linked to a modification in Na,K-ATPase activity through the PKA and NO-cyclic GMP pathway. PMID:14614957

  4. Cyclic AMP levels during induction and repression of cellulase biosynthesis in Thermomonospora curvata.

    PubMed Central

    Wood, W E; Neubauer, D G; Stutzenberger, F J

    1984-01-01

    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 nonmetabolizable 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. PMID:6094497

  5. RGS17, an Overexpressed Gene in Human Lung and Prostate Cancer, Induces Tumor Cell Proliferation Through the Cyclic AMP-PKA-CREB Pathway

    PubMed Central

    James, Michael A.; Lu, Yan; Liu, Yan; Vikis, Haris G.; You, Ming

    2009-01-01

    We have identified RGS17 as a commonly induced gene in lung and prostate tumors. Through microarray and gene expression analysis, we show that expression of RGS17 is up-regulated in 80% of lung tumors, and also up-regulated in prostate tumors. Through knockdown and overexpression of RGS17 in tumor cells, we show that RGS17 confers a proliferative phenotype and is required for the maintenance of the proliferative potential of tumor cells. We show through exon microarray, transcript analysis, and functional assays that RGS17 promotes cyclic AMP (cAMP)-responsive element binding protein (CREB)-responsive gene expression, increases cAMP levels, and enhances forskolin-mediated cAMP production. Furthermore, inhibition of cAMP-dependent kinase prevents tumor cell proliferation, and proliferation is partially rescued by RGS17 overexpression. In the present study, we show a role for RGS17 in the maintenance of tumor cell proliferation through induction of cAMP signaling and CREB phosphorylation. The prevalence of the induction of RGS17 in tumor tissues of various types further implicates its importance in the maintenance of tumor growth. PMID:19244110

  6. Cyclic AMP as a modulator of NaCl transport in gills of the euryhaline Chinese crab Eriocheir sinensis

    Microsoft Academic Search

    A. Bianchini; R. Gilles

    1990-01-01

    Experiments on the effect of cyclic AMP on Na+ and Cl- transport pathways were performed on isolated, perfused preparations of the posterior, osmoregulating gills of the euryhaline Chinese crabEriocheir sinensis. The crabs were caught during the autumn of 1987 in freshwater lakes near Emden (Federal Republic of Germany). N6-2'-O-dibutyryl adenosine 3':5'-cyclic monophosphate (db-cAMP), 3-isobutyl-1-methylxanthine (IBMX), and 7ß-acetoxy-8,13-epoxy-1a, 6ß, 9a-trihydroxy-labd-14-ene-11-one (forskolin)

  7. Food restriction increases NMDA receptor-mediated calcium—calmodulin kinase II and NMDA receptor\\/extracellular signal-regulated kinase 1\\/2-mediated cyclic amp response element-binding protein phosphorylation in nucleus accumbens upon D-1 dopamine receptor stimulation in rats

    Microsoft Academic Search

    S. L. Haberny; K. D. Carr

    2005-01-01

    Biological drive states exert homeostatic control in part by increasing the reinforcing effects of environmental incentive stimuli. An apparent by-product of this adaptive response is the enhanced acquisition of drug self-administration behavior in food-restricted (FR) animals. While previous research has demonstrated increased central sensitivity to rewarding effects of abused drugs and direct dopamine (DA) receptor agonists in FR subjects, the

  8. Adrenoceptor responsiveness in bronchial asthma

    PubMed Central

    Trembath, P. W.; Shaw, J.

    1976-01-01

    1 The effect of isoprenaline inhalation on plasma levels of cyclic AMP has been studied in a group of normal subjects and compared to a group of asthmatics. 2 The normal subjects had a prompt rise in their plasma cyclic AMP level, and when compared to the asthmatic group, had a significantly greater percentage rise in plasma cyclic AMP from the basal levels. 3 The markedly attenuated response to isoprenaline inhalation in the asthmatic group is consistent with the concept that asthmatics have a relative impairment of ?-adrenoceptor function. 4 These results support the in vitro studies demonstrating that lymphocytes from asthmatic subjects incubated with isoprenaline produce less cyclic AMP than those from normal subjects. PMID:22216521

  9. Steady-State Modulation of Voltage-Gated K+ Channels in Rat Arterial Smooth Muscle by Cyclic AMP-Dependent Protein Kinase and Protein Phosphatase 2B

    PubMed Central

    Brignell, Jennifer L.; Perry, Matthew D.; Nelson, Carl P.; Willets, Jonathon M.; Challiss, R. A. John; Davies, Noel W.

    2015-01-01

    Voltage-gated potassium channels (Kv) are important regulators of membrane potential in vascular smooth muscle cells, which is integral to controlling intracellular Ca2+ concentration and regulating vascular tone. Previous work indicates that Kv channels can be modulated by receptor-driven alterations of cyclic AMP-dependent protein kinase (PKA) activity. Here, we demonstrate that Kv channel activity is maintained by tonic activity of PKA. Whole-cell recording was used to assess the effect of manipulating PKA signalling on Kv and ATP-dependent K+ channels of rat mesenteric artery smooth muscle cells. Application of PKA inhibitors, KT5720 or H89, caused a significant inhibition of Kv currents. Tonic PKA-mediated activation of Kv appears maximal as application of isoprenaline (a ?-adrenoceptor agonist) or dibutyryl-cAMP failed to enhance Kv currents. We also show that this modulation of Kv by PKA can be reversed by protein phosphatase 2B/calcineurin (PP2B). PKA-dependent inhibition of Kv by KT5720 can be abrogated by pre-treatment with the PP2B inhibitor cyclosporin A, or inclusion of a PP2B auto-inhibitory peptide in the pipette solution. Finally, we demonstrate that tonic PKA-mediated modulation of Kv requires intact caveolae. Pre-treatment of the cells with methyl-?-cyclodextrin to deplete cellular cholesterol, or adding caveolin-scaffolding domain peptide to the pipette solution to disrupt caveolae-dependent signalling each attenuated PKA-mediated modulation of the Kv current. These findings highlight a novel, caveolae-dependent, tonic modulatory role of PKA on Kv channels providing new insight into mechanisms and the potential for pharmacological manipulation of vascular tone. PMID:25793374

  10. Cyclic AMP-dependent protein kinase controls energy interconversion during the catalytic cycle of the yeast copper-ATPase.

    PubMed

    Valverde, Rafael H F; Morin, Isabelle; Lowe, Jennifer; Mintz, Elisabeth; Cuillel, Martine; Vieyra, Adalberto

    2008-03-19

    The pathogenesis of human Menkes and Wilson diseases depends on alterations in copper transport. Some reports suggest that intracellular traffic of copper might be regulated by kinase-mediated phosphorylation. However, there is no evidence showing the influence of kinase-related processes in coupled ATP hydrolysis/copper transport cycles. Here, we show that cyclic AMP-dependent protein kinase (PKA) regulates Ccc2p, the yeast Cu(I)-ATPase, with PKA-mediated phosphorylation of a conserved serine (Ser258) being crucial for catalysis. Long-range intramolecular communication between Ser258 and Asp627 (at the catalytic site) modulates the key pumping event: the conversion of the high-energy to the low-energy phosphorylated intermediate associated with copper release. PMID:18291109

  11. [Regulation of global transcriptional factor cyclic amp receptor protein and its metabolic engineering application in Escherichia coli].

    PubMed

    Wang, Xianju; Lü, Jing; Fu, Pengcheng

    2014-11-01

    Cyclic amp receptor protein (CRP) is a global transcriptional factor in many prokaryotes, capable of governing nearly half of the total genes in Escherichia coli. Through the method of error-prone PCR or DNA shuffling, we can first obtain CRP mutant library and then get the expected cell phenotype with enhanced resistance. In this article, we reviewed the following desired phenotype: enhanced tolerance towards oxidative stress, improved osmotolerance, enhanced organic solvent (toluene) tolerance, improved acetate tolerance of E. coli fermentation and improved ethanol tolerance during bio-ethanol production. We then concluded that CRP can also be applied in other host cells to get desired phenotypes. Last, we predicted potential applications of mutant CRP transcriptional factor. PMID:25985516

  12. Cyclic AMP-Mediated Suppression of Neutrophil Extracellular Trap Formation and Apoptosis by the Bordetella pertussis Adenylate Cyclase Toxin

    PubMed Central

    Gray, Mary C.; Hewlett, Erik L.

    2014-01-01

    The adenylate cyclase toxin (ACT) of Bordetella pertussis intoxicates target cells by generating supraphysiologic levels of intracellular cyclic AMP (cAMP). Since ACT kills macrophages rapidly and potently, we asked whether ACT would also kill neutrophils. In fact, ACT prolongs the neutrophil life span by inhibiting constitutive apoptosis and preventing apoptosis induced by exposure to live B. pertussis. Imaging of B. pertussis-exposed neutrophils revealed that B. pertussis lacking ACT induces formation of neutrophil extracellular traps (NETs), whereas wild-type B. pertussis does not, suggesting that ACT suppresses NET formation. Indeed, ACT inhibits formation of NETs by generating cAMP and consequently inhibiting the oxidative burst. Convalescent-phase serum from humans following clinical pertussis blocks the ACT-mediated suppression of NET formation. These studies provide novel insight into the phagocyte impotence caused by ACT, which not only impairs neutrophil function but also inhibits death of neutrophils by apoptosis and NETosis. PMID:25287922

  13. Production and release of cyclic AMP by Daphnia pulex: implications of grazing activity

    SciTech Connect

    Francko, D.A.; Wetzel, R.G.

    1982-04-01

    Daphnia pulex, a common cladoceran zooplankton species, contains tissue cAMP concentrations similar to those found in algae, bacteria, and aquatic macrophytes. Daphnia release significant quantities of cAMP into the extracellular medium. Release of algal cellular cAMP as a result of digestive degradation of algal cells may also be an important source of dissolved cAMP in lakewater.

  14. Production and release of cyclic AMP by Daphnia pulex: implications of grazing activity

    SciTech Connect

    Francko, D.A. (Michigan State Univ., Hickory Corners); Wetzel, R.G.

    1982-04-01

    Daphnia pulex, a common cladoceran zooplankton species, contains tissue cAMP concentrations similar to those found in algae, bacteria, and aquatic macrophytes. Daphnia release significant quantities of cAMP into the extracellular medium. Release of algal cellular cAMP as a result of digstive degradation of algal cells may also be an important source of dissolved cAMP in lakewater.

  15. Cyclic AMP Activates Anion Channels in Cultured Bovine Corneal Endothelial Cells

    Microsoft Academic Search

    JOSEPH A BONANNO; S. P SRINIVAS

    1997-01-01

    Ion coupled fluid transport by the corneal endothelium is stimulated by adenosine through a cAMP dependent mechanism. This study examines if anion conductance is enhanced by cAMP and, hence by adenosine. Cl?fluxes, measured by changes in fluorescence of the Cl?sensitive dye SPQ, following removal or re-addition of Cl?Ringer, could be accelerated by 20 ?Mforskolin or 10 ?Madenosine. The cAMP cocktail

  16. Cyclic AMP and Afferent Activity Govern Bidirectional Synaptic Plasticity in Striatopallidal Neurons

    PubMed Central

    Augustin, Shana M.; Beeler, Jeff A.; Zhuang, Xiaoxi

    2014-01-01

    Recent experimental evidence suggests that the low dopamine conditions in Parkinson's disease (PD) cause motor impairment through aberrant motor learning. Those data, along with computational models, suggest that this aberrant learning results from maladaptive corticostriatal plasticity and learned motor inhibition. Dopaminergic modulation of both corticostriatal long-term depression (LTD) and long-term potentiation (LTP) is proposed to be critical for these processes; however, the regulatory mechanisms underlying bidirectional corticostriatal plasticity are not fully understood. Previously, we demonstrated a key role for cAMP signaling in corticostriatal LTD. In this study, mouse brain slices were used to perform a parametric experiment that tested the impact of varying both intracellular cAMP levels and the strength of excitatory inputs on corticostriatal plasticity. Using slice electrophysiology in the dorsolateral striatum, we demonstrate that both LTP and LTD can be sequentially induced in the same D2-expressing neuron and that LTP was strongest with high intracellular cAMP and LFS, whereas LTD required low intracellular cAMP and high-frequency stimulation. Our results provide a molecular and cellular basis for regulating bidirectional corticostriatal synaptic plasticity and may help to identify novel therapeutic targets for blocking or reversing the aberrant synaptic plasticity that likely contributes to motor deficits in PD. PMID:24806695

  17. 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

    Zhange, Y.; Lin, J.X.; Vilcek, J.

    1988-05-05

    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.

  18. Putting on the Brakes: Cyclic AMP as a Multipronged Controller of Macrophage Function

    NSDL National Science Digital Library

    Marc Peters-Golden (Ann Arbor; University of Michigan Medical School REV)

    2009-06-16

    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.

  19. Photolysis of caged cyclic AMP in the ciliary cytoplasm of the newt olfactory receptor cell

    PubMed Central

    Takeuchi, Hiroko; Kurahashi, Takashi

    2002-01-01

    The effects of cyclic nucleotide monophosphate (cNMP) in the ciliary cytoplasm of the olfactory receptor cell were examined by using photolysis of caged cNMP loaded from the whole-cell patch clamp pipette. Illumination of the cilia induced an inward current at ?50 mV. The current amplitude was voltage dependent and the polarity was reversed at +10 mV. The amplitude of the light-induced current was dependent on both light intensity and duration. The intensity-response relation was fitted well by the Hill equation with a coefficient (nH) of 4.99 ± 2.66 (mean ± s.d., n = 19) and the duration-response relation with a coefficient of 4.03 ± 1.43 (n = 17). The activation time course of adenylyl cyclase was estimated by comparing the light-induced response with the odorant-induced response. Adenylyl cyclase was activated approximately 260 ms later from the onset of the odorant-stimulation. The light-induced current developed very sharply. This could be explained by the sequential openings of cAMP-gated and Ca2+-activated Cl? channels. At +100 mV, where Ca2+ influx is expected to be very small, the current rising phase became less steep. When the cells were stimulated by long steps of either odour or light, the odorant-induced current showed stronger decay than the light-induced response. This observation suggests that the molecular system regulating desensitization is situated upstream of cAMP production. PMID:12068043

  20. Effects of Dibutyryl Cyclic-AMP on Survival and Neuronal Differentiation of Neural Stem/Progenitor Cells Transplanted into Spinal Cord Injured Rats

    PubMed Central

    Kim, Howard; Zahir, Tasneem; Tator, Charles H.; Shoichet, Molly S.

    2011-01-01

    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 exposure either in vitro or in vivo through the controlled release of dbcAMP encapsulated within poly(lactic-co-glycolic acid) (PLGA) microspheres and embedded within chitosan guidance channels. NSPCs, seeded in fibrin scaffolds within the channels, differentiated in vitro to betaIII-tubulin positive neurons by immunostaining and mRNA expression, in response to dbcAMP released from PLGA microspheres. After transplantation in spinal cord injured rats, the survival and differentiation of NSPCs was evaluated. Untreated NSPCs, NSPCs transplanted with dbcAMP-releasing microspheres, and NSPCs pre-differentiated with dbcAMP for 4 days in vitro were transplanted after rat spinal cord transection and assessed 2 and 6 weeks later. Interestingly, NSPC survival was highest in the dbcAMP pre-treated group, having approximately 80% survival at both time points, which is remarkable given that stem cell transplantation often results in less than 1% survival at similar times. Importantly, dbcAMP pre-treatment also resulted in the greatest number of in vivo NSPCs differentiated into neurons (37±4%), followed by dbcAMP-microsphere treated NSPCs (27±14%) and untreated NSPCs (15±7%). The reverse trend was observed for NSPC-derived oligodendrocytes and astrocytes, with these populations being highest in untreated NSPCs. This combination strategy of stem cell-loaded chitosan channels implanted in a fully transected spinal cord resulted in extensive axonal regeneration into the injury site, with improved functional recovery after 6 weeks in animals implanted with pre-differentiated stem cells in chitosan channels. PMID:21738784

  1. Modulation of a human lymphoblastoid B cell line by cyclic AMP. Ig secretion and phosphatidylcholine metabolism

    SciTech Connect

    Shearer, W.T.; Patke, C.L.; Gilliam, E.B.; Rosenblatt, H.M.; Barron, K.S.; Orson, F.M.

    1988-09-01

    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.

  2. Adrenergic receptor stimulation of the mitogen-activated protein kinase cascade and cardiac hypertrophy.

    PubMed Central

    Bogoyevitch, M A; Andersson, M B; Gillespie-Brown, J; Clerk, A; Glennon, P E; Fuller, S J; Sugden, P H

    1996-01-01

    Phenylephrine and noradrenaline (alpha-adrenergic agonism) or isoprenaline (beta-adrenergic agonism) stimulated protein synthesis rates, increased the activity of the atrial natriuretic factor gene promoter and activated mitogen-activated protein kinase (MAPK). The EC50 for MAPK activation by noradrenaline was 2-4 microM and that for isoprenaline was 0.2-0.3 microM. Maximal activation of MAPK by isoprenaline was inhibited by the beta-adrenergic antagonist, propranolol, whereas the activation by noradrenaline was inhibited by the alpha1-adrenergic antagonist, prazosin. FPLC on a Mono-Q column separated two peaks of MAPK (p42MAPK and p44MAPK) and two peaks of MAPK-activating activity (MEK) activated by isoprenaline or noradrenaline. Prolonged phorbol ester exposure partially down-regulated the activation of MAPK by noradrenaline but not by isoprenaline. This implies a role for protein kinase C in MAPK activation by noradrenaline but not isoprenaline. A role for cyclic AMP in activation of the MAPK pathway was eliminated when other agonists that elevate cyclic AMP in the cardiac myocyte did not activate MAPK. In contrast, MAPK was activated by exposure to ionomycin, Bay K8644 or thapsigargin that elevate intracellular Ca2+. Furthermore, depletion of extracellular Ca2+ concentrations with bis-(o-aminophenoxy)ethane-NNN'N'-tetra-acetic acid (BAPTA) or blocking of the L-type Ca2+ channel with nifepidine or verapamil inhibited the response to isoprenaline without inhibiting the responses to noradrenaline. We conclude that alpha- and beta-adrenergic agonists can activate the MEK/MAPK pathway in the heart by different signalling pathways. Elevation of intracellular Ca2+ rather than cyclic AMP appears important in the activation of MAPK by isoprenaline in the cardiac myocyte. PMID:8660271

  3. Cyclic AMP levels in several macroalgae and their relation to light quantity and quality.

    PubMed

    Gordillo, Francisco J L; Segovia, María; López-Figueroa, Félix

    2004-02-01

    Total cAMP levels were measured in the macroalgae Dictyota dichotoma, Gelidium sesquipedale and Ulva rigida under different light conditions in order to study its regulation either by phytochrome or photosynthesis. Incubation in red or far-red light did not promote a phytochrome-like response; instead, it showed a synergistic effect upon cAMP accumulation. cAMP levels seemed to depend on the amount of energy applied. The correlation between photosynthetic oxygen evolution and cAMP variations at sub-saturating white light irradiance pointed to photosynthetic electron transport as involved in the regulation of cAMP accumulation at least in G. sesquipedale and U. rigida. Inhibitors of thylakoidal and mitochondrial electron transport chains reduced cAMP levels in 70 to 99%. We conclude that cAMP accumulation could be regulated by photosynthetic activity rather than phytochrome in the macroalgae studied. PMID:15022836

  4. CCR-08-0827 Version 2 Targeted inhibition of cyclic AMP phosphodiesterase-4 promotes brain tumor regression

    PubMed Central

    Goldhoff, Patricia; Warrington, Nicole; Limbrick, David D.; Hope, Andrew; Woerner, B. Mark; Jackson, Erin; Perry, Arie; Piwnica-Worms, David; Rubin, Joshua B.

    2008-01-01

    Statement of Clinical Relevance Therapies that can overcome the resistance of malignant brain tumors would be a major clinical advance. Here, we investigate the role of cAMP Phosphodiesterase-4 in stimulating brain tumor growth and the therapeutic utility of cAMP Phosphodiesterase-4 inhibition in the treatment of malignant brain tumors. Cyclic AMP Phosphodiesterase-4 was widely expressed in human brain tumors of glial and neuronal lineage, and forced expression of PDE4A1 accelerated intracranial glioblastoma and medulloblastoma xenograft growth. Moreover, targeted inhibition of PDE4, in combination with standard radiation and chemotherapy, induced a unique regression of established intracranial glioblastoma xenografts. These findings identify PDE4 as a novel molecular target for brain tumor therapy and indicate that PDE4 inhibition should be evaluated in clinical trials for malignant brain tumors. Purpose As favorable outcomes from malignant brain tumors remain limited by poor survival and treatment-related toxicity, novel approaches to cure are essential. Previously, we identified the cyclic AMP phosphodiesterase-4 (PDE4) inhibitor Rolipram as a potent anti-tumor agent. Here, we investigate the role of PDE4 in brain tumors and examine the utility of PDE4 as a therapeutic target. Experimental Design Immunohistochemistry was used to evaluate the expression pattern of a subfamily of PDE4, PDE4A, in multiple brain tumor types. To evaluate the effect of PDE4A on growth, a brain-specific isoform, PDE4A1 was overexpressed in xenografts of Daoy medulloblastoma and U87 glioblastoma cells. To determine therapeutic potential of PDE4 inhibition, Rolipram, temozolomide, and radiation were tested alone and in combination on mice bearing intracranial U87 xenografts. Results We found that PDE4A is expressed in medulloblastoma, glioblastoma, oligodendroglioma, ependymoma and meningioma. Moreover, when PDE4A1 was overexpressed in Daoy medulloblastoma and U87 glioblastoma cells, in vivo doubling times were significantly shorter for PDE4A1 overexpressing xenografts compared to controls. In long-term survival and bioluminescence studies, Rolipram in combination with first-line therapy for malignant gliomas (temozolomide and conformal radiation therapy) enhanced the survival of mice bearing intracranial xenografts of U87 glioblastoma cells. Bioluminescence imaging indicated that while temozolomide and radiation therapy arrested intracranial tumor growth, the addition of Rolipram to this regimen resulted in tumor regression. Conclusion This study shows that PDE4 is widely expressed in brain tumors and promotes their growth, and that inhibition with Rolipram overcomes tumor resistance and mediates tumor regression. PMID:19047098

  5. Cyclic AMP concentrations in dendritic cells induce and regulate Th2 immunity and allergic asthma.

    PubMed

    Lee, Jihyung; Kim, Tae Hoon; Murray, Fiona; Li, Xiangli; Choi, Sara S; Broide, David H; Corr, Maripat; Lee, Jongdae; Webster, Nicholas J G; Insel, Paul A; Raz, Eyal

    2015-02-01

    The inductive role of dendritic cells (DC) in Th2 differentiation has not been fully defined. We addressed this gap in knowledge by focusing on signaling events mediated by the heterotrimeric GTP binding proteins G?s, and G?i, which respectively stimulate and inhibit the activation of adenylyl cyclases and the synthesis of cAMP. We show here that deletion of Gnas, the gene that encodes G?s in mouse CD11c(+) cells (Gnas(?CD11c) mice), and the accompanying decrease in cAMP provoke Th2 polarization and yields a prominent allergic phenotype, whereas increases in cAMP inhibit these responses. The effects of cAMP on DC can be demonstrated in vitro and in vivo and are mediated via PKA. Certain gene products made by Gnas(?CD11c) DC affect the Th2 bias. These findings imply that G protein-coupled receptors, the physiological regulators of G?s and G?i activation and cAMP formation, act via PKA to regulate Th bias in DC and in turn, Th2-mediated immunopathologies. PMID:25605931

  6. Intact parathyroid hormone concentration and cyclic AMP metabolism in thyroid disease.

    PubMed

    Fraser, W D; Logue, F C; MacRitchie, K; Wilson, R M; Gray, H W; Beastall, G H; O'Reilly, D S

    1991-06-01

    In 35 thyrotoxic patients and 35 patients receiving thyroxine replacement therapy mean serum intact parathyroid hormone concentrations were lower than in euthyroid normal volunteer controls. In 20 hypothyroid patients intact PTH was increased relative to euthyroid controls. Mean serum adjusted calcium was increased in thyrotoxic patients relative to euthyroid controls and in 8 toxic patients with elevated serum adjusted calcium (greater than 2.60 mmol/l) intact PTH was below the assay detection limit (less than 0.5 pmol/l). Indices of PTH activity were consistent with intact PTH measurements in thyrotoxic patients with nephrogenous cyclic adenosine monophosphate lower, tubular maximum reabsorption of phosphate higher, and urinary calcium creatinine ratio higher than controls. In hypothyroid patients these indices of PTH activity suggest relative end organ resistance to PTH with nephrogenous cyclic adenosine monophosphate similar, tubular maximum reabsorption of phosphate similar, and calcium creatinine ratio lower than in controls. In treated hypothyroid patients nephrogenous cyclic adenosine monophosphate was higher, tubular maximum reabsorption of phosphate similar, and calcium creatinine ratio higher than in controls. These results are compatible with the hypothesis that thyroid status modifies the renal responses to PTH (1-84). PMID:1648852

  7. Cyclic AMP mediates the direct antiproliferative action of mismatched double-stranded RNA.

    PubMed

    Hubbell, H R; Boyer, J E; Roane, P; Burch, R M

    1991-02-01

    Previous experiments have demonstrated that double-stranded RNAs (dsRNAs) can exert an antiproliferative effect on human tumor cells, independent of interferon (IFN) induction. However, the mechanism by which dsRNAs inhibit tumor growth has not been elucidated. As a first step in determining the molecular events responsible for growth arrest, we have explored the role of signal transduction through the cAMP system in the antiproliferative effect of the mismatched dsRNA, r(I)n.r(C12,U)n (Ampligen). These studies utilized the human glioma cell line A1235, which does not produce detectable levels of IFN-alpha, -beta, or -gamma in response to mismatched dsRNA treatment. Treatment of A1235 cells with mismatched dsRNA in combination with either 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), which inhibits cAMP-dependent protein kinase and protein kinase C, or N-(2-guanidinoethyl)-5-isoquinolinesulfonamide (HA1004), which preferentially inhibits the cAMP-dependent protein kinase, yielded an antagonism of the mismatched dsRNA-induced antiproliferative effect. Measurement of adenylate cyclase activation showed a dose-dependent increase in activity at antiproliferative mismatched dsRNA concentrations, but not at lower, nonantiproliferative doses. This increase in activity was rapid, seen as early as 30 sec after initiation of treatment, and it was sustained at peak levels for 1-2 hr. Analysis of the intracellular cAMP concentration gave similar kinetics of induction. Exposure of cells to the stable cAMP analogue dibutyryl cAMP yielded dose-dependent inhibition of cell growth. The cAMP phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine also inhibited proliferation. In contrast, neither H-7 nor HA1004 had an effect on growth inhibition induced by human natural IFN-alpha treatment. In addition, antiproliferative doses of IFN-alpha did not increase cAMP concentrations. These results indicate that the cAMP system is utilized by mismatched dsRNA as an early signal transduction mechanism for growth control. Furthermore, the antiproliferative effects induced by mismatched dsRNA and IFN can occur by different mechanisms of action. PMID:1846967

  8. Cyclic nucleotide responses and radiation-induced mitotic delay in Physarum polycephalum

    SciTech Connect

    Daniel, J.W.; Oleinick, N.L.

    1984-02-01

    The response of the plasmodial levels of cyclic AMP and cyclic GMP in Physarum polycephalum to several putative phosphodiesterase inhibitors and to ionizing radiation has been measured. Isobutylmethylxanthine (2 mM) induces a rapid transient threefold elevation of cyclic AMP alone, with maximum response in about 10 min and return to the base line in about 30 min. Theophylline (2 mM) induces a rapid, sustained twofold elevation of cyclic GMP only. Caffeine (2mM) and Ro-20-1724 (18 ..mu..M) both elicit a rapid transient rise in cyclic AMP, resembling the isobutylmethylxanthine response, and a slow transient elevation of the cyclic GMP level. Of particular interest is the rapid threefold transient elevation of the cyclic AMP, but not of the cyclic GMP, level by ..gamma.. radiation.

  9. Action of 50 Hz magnetic fields on cyclic AMP and intercellular communication in monolayers and spheroids of mammalian cells

    SciTech Connect

    Schimmelpfeng, J.; Stein, J.C.; Dertinger, H. [Research Center Karlsruhe (Germany). Inst. of Toxicology

    1995-12-31

    To investigate the influence of physiological parameters such as cell density and three-dimensional cell contact on the biological action of a 2mT/50 Hz magnetic field, mouse fibroblasts were exposed as monolayers and as multicellular spheroids. Changes in cyclic AMP content of cells and alterations in gap junction-mediated intercellular communication were measured immediately after 5 min of exposure to the field. In monolayers of intermediate cell density (1 {times} 10{sup 5} cells/cm{sup 2}), the field treatment caused an increase in cAMP to 121% of the control level, whereas, at 3 {times} 10{sup 5} cells/cm{sup 2} (near confluence), a decrease to 88% of the unexposed cells was observed. Furthermore, field exposure stimulated gap-junction communication to 160% of the control level as determined by Lucifer yellow dye exchange. In spheroids, alterations in the radial profile of cellular cAMP were observed that were due both to field-induced local cAMP changes and to increased gap-junction permeability for this second messenger, the latter causing radial cAMP gradients to be flattened. The results indicate a strong dependence of field action on physiological parameters of the system exposed.

  10. Intracellular lithium and cyclic AMP levels are mutually regulated in neuronal cells.

    PubMed

    Montezinho, L P; B Duarte, C; Fonseca, C P; Glinka, Y; Layden, B; Mota de Freitas, D; Geraldes, C F G C; Castro, M M C A

    2004-08-01

    In this work, we studied the effect of intracellular 3',5'-cyclic adenosine monophosphate (cAMP) on Li+ transport in SH-SY5Y cells. The cells were stimulated with forskolin, an adenylate cyclase activator, or with the cAMP analogue, dibutyryl-cAMP. It was observed that under forskolin stimulation both the Li+ influx rate constant and the Li+ accumulation in these cells were increased. Dibutyryl-cAMP also increased Li+ uptake and identical results were obtained with cortical and hippocampal neurons. The inhibitor of the Na+/Ca2+ exchanger, KB-R7943, reduced the influx of Li+ under resting conditions, and completely inhibited the effect of forskolin on the accumulation of the cation. Intracellular Ca2+ chelation, or inhibition of N-type voltage-sensitive Ca2+ channels, or inhibition of cAMP-dependent protein kinase (PKA) also abolished the effect of forskolin on Li+ uptake. The involvement of Ca2+ on forskolin-induced Li+ uptake was confirmed by intracellular free Ca2+ measurements using fluorescence spectroscopy. Exposure of SH-SY5Y cells to 1 mm Li+ for 24 h increased basal cAMP levels, but preincubation with Li+, at the same concentration, decreased cAMP production in response to forskolin. To summarize, these results demonstrate that intracellular cAMP levels regulate the uptake of Li+ in a Ca(2+)-dependent manner, and indicate that Li+ plays an important role in the homeostasis of this second messenger in neuronal cells. PMID:15287898

  11. A large contribution of a cyclic AMP-independent pathway to turtle olfactory transduction.

    PubMed

    Kashiwayanagi, M; Kawahara, H; Hanada, T; Kurihara, K

    1994-06-01

    Although multiple pathways are involved in the olfactory transduction mechanism, cAMP-dependent pathway has been considered to contribute mainly to the transduction. We examined the degree of contribution of cAMP-independent pathway to the turtle olfactory response by recording inward currents from isolated cells, nerve impulses from cilia and olfactory bulbar responses. The results obtained by the three recordings were essentially consistent with each other, but detail studies were carried out by recording the bulbar response to obtain quantitative data. Application of an odorant cocktail to the isolated olfactory neuron after injection of 1 mM cAMP from the patch pipette elicited a large inward current. Mean amplitude of inward currents evoked by the cocktail with 1 mM cAMP in the patch pipette was similar to that without cAMP in the pipette. Application of the cocktail after the response to 50 microM forskolin was adapted also induced a large inward current. Application of the odorant cocktail to the olfactory epithelium, after the response to 50 microM forskolin was adapted, brought about an appreciable increase in the impulse frequency. The bulbar response to forskolin alone reached a saturation level around 10 microM. After the response to 50 microM forskolin was adapted, 11 species of odorants were applied to the olfactory epithelium. The magnitudes of responses to the odorants after forskolin were 45-80% of those of the control responses. There was no essential difference in the degree of the suppression by forskolin between cAMP- and IP3-producing odorants classified in the rat, suggesting that certain part of the forskolin-suppressive component was brought about by nonspecific action of forskolin. Application of a membrane permeant cAMP analogue, cpt-cAMP elicited a large response, and 0.1 mM citralva after 3 mM cpt-cAMP elicited 51% of the control response which was close to the response to citralva after 50 microM forskolin. A membrane permeant cGMP analogue, db-cGMP elicited a small response and the response to 0.1 mM citralva was unaffected by db-cGMP. It was concluded that cAMP-independent (probably IP3-independent) pathway greatly contributes to the turtle olfactory transduction. PMID:7523576

  12. A large contribution of a cyclic AMP-independent pathway to turtle olfactory transduction

    PubMed Central

    1994-01-01

    Although multiple pathways are involved in the olfactory transduction mechanism, cAMP-dependent pathway has been considered to contribute mainly to the transduction. We examined the degree of contribution of cAMP-independent pathway to the turtle olfactory response by recording inward currents from isolated cells, nerve impulses from cilia and olfactory bulbar responses. The results obtained by the three recordings were essentially consistent with each other, but detail studies were carried out by recording the bulbar response to obtain quantitative data. Application of an odorant cocktail to the isolated olfactory neuron after injection of 1 mM cAMP from the patch pipette elicited a large inward current. Mean amplitude of inward currents evoked by the cocktail with 1 mM cAMP in the patch pipette was similar to that without cAMP in the pipette. Application of the cocktail after the response to 50 microM forskolin was adapted also induced a large inward current. Application of the odorant cocktail to the olfactory epithelium, after the response to 50 microM forskolin was adapted, brought about an appreciable increase in the impulse frequency. The bulbar response to forskolin alone reached a saturation level around 10 microM. After the response to 50 microM forskolin was adapted, 11 species of odorants were applied to the olfactory epithelium. The magnitudes of responses to the odorants after forskolin were 45-80% of those of the control responses. There was no essential difference in the degree of the suppression by forskolin between cAMP- and IP3- producing odorants classified in the rat, suggesting that certain part of the forskolin-suppressive component was brought about by nonspecific action of forskolin. Application of a membrane permeant cAMP analogue, cpt-cAMP elicited a large response, and 0.1 mM citralva after 3 mM cpt- cAMP elicited 51% of the control response which was close to the response to citralva after 50 microM forskolin. A membrane permeant cGMP analogue, db-cGMP elicited a small response and the response to 0.1 mM citralva was unaffected by db-cGMP. It was concluded that cAMP- independent (probably IP3-independent) pathway greatly contributes to the turtle olfactory transduction. PMID:7523576

  13. Abnormal function of the vasopressin-cyclic-AMP-aquaporin2 axis during urine concentrating and diluting in patients with reduced renal function. A case control study

    PubMed Central

    2010-01-01

    Background The kidneys ability to concentrate and dilute urine is deteriorated during progressive renal insufficiency. We wanted to test the hypothesis that these phenomena could be attributed to an abnormal function of the principal cells in the distal part of the nephron. Methods Healthy control subjects and patients with chronic kidney diseases were studied. Group 1 comprised healthy subjects, n = 10. Groups 2-4 comprised patients with chronic kidney disease (Group 2, n = 14, e-GFR ? 90 m1/min; Group 3, n = 11, 60 m1/min ? e-GFR < 90 ml/min; and Group 4, n = 16, 15 ml/min ? e-GFR < 60 ml/min). The subjects collected urine during 24 hours. A urine concentrating test was done by thirsting during the following 12 hours. Thereafter, a urine diluting test was performed with a water load of 20 ml/kg body weight. The effect variables were urinary excretions of aquaporin2 (u-AQP2), cyclic-AMP (u-c-AMP), urine volume (UV), free water clearance (CH2O), urine osmolarity (u-Osm), and plasma arginine vasopressin (p-AVP). Results After fluid deprivation, u-Osm increased. In all groups, UV and CH2O decreased and u-AQP2 and u-c-AMP increased in Groups 1 and 2, but were unchanged in Group 3 and 4. P-AVP was significantly higher in Group 4 than in the other groups. During urine diluting, UV and CH2O reached significantly higher levels in Groups 1-3 than Group 4. Both before and after water loading, u-AQP2 and p-AVP were significantly higher and u-c-AMP was significantly lower in Group 4 than the other groups. Estimated-GFR was correlated negatively to p-AVP and positively to u-c-AMP. Conclusions Patients with moderately severe chronic kidney disease have a reduced renal concentrating and diluting capacity compared to both patients with milder chronic kidney disease and healthy control subjects. These phenomena can be attributed, at least partly, to an abnormally decreased response in the AVP-c-AMP-AQP2 axis. ClinicalTrials.Gov Identifier: NCT00313430 PMID:20923561

  14. A large contribution of a cyclic AMP-independent pathway to turtle olfactory transduction

    Microsoft Academic Search

    MAKOTO KASHIWAYANAGI; HAJIME KAWAHARA; TAKUYA HANADA; KENZO KURIHARA

    1994-01-01

    A B S T RAC T Although multiple pathways are involved in the olfactory transduction mechanism, cAMP-dependent pathway has been considered to contribute mainly to the transduction, We examined the degree of contribution of cAMP-independent pathway to the turtle olfactory response by recording inward currents from isolated cells, nerve impulses from cilia and olfactory bulbar responses. The results obtained by

  15. Parathyroid hormone promotes the disassembly of cytoskeletal actin and myosin in cultured osteoblastic cells: Mediation by cyclic AMP

    SciTech Connect

    Egan, J.J.; Gronowicz, G.; Rodan, G.A. (National Institutes of Diabetes, Digestive, and Kidney Diseases, Bethesda, MD (USA))

    1991-01-01

    Parathyroid hormone (PTH) alters the shape of osteoblastic cells both in vivo and in vitro. In this study, we examined the effect of PTH on cytoskeletal actin and myosin, estimated by polyacrylamide gel electrophoresis of Triton X-100 (1%) nonextractable proteins. After 2-5 minutes, PTH caused a rapid and transient decrease of 50-60% in polymerized actin and myosin associated with the Triton X-100 nonextractable cytoskeleton. Polymerized actin returned to control levels by 30 min. The PTH effect was dose-dependent with an IC50 of about 1 nM, and was partially inhibited by the (3-34) PTH antagonist. PTH caused a rapid transient rise in cyclic AMP (cAMP) in these cells that peaked at 4 min, while the nadir in cytoskeletal actin and myosin was recorded around 5 min. The intracellular calcium chelator Quin-2/AM (10 microM) also decreased cytoskeletal actin and myosin, to the same extent as did PTH (100 nM). To distinguish between cAMP elevation and Ca++ reduction as mediators of PTH action, we measured the phosphorylation of the 20 kD (PI 4.9) myosin light chain in cells preincubated with (32P)-orthophosphate. The phosphorylation of this protein decreased within 2-3 min after PTH addition and returned to control levels after 5 min. The calcium ionophore A-23187 did not antagonize this PTH effect. Visualization of microfilaments with rhodamine-conjugated phalloidin showed that PTH altered the cytoskeleton by decreasing the number of stress fibers. These changes in the cytoskeleton paralleled changes in the shape of the cells from a spread configuration to a stellate form with retracting processes. The above findings indicate that the alteration in osteoblast shape produced by PTH involve relatively rapid and transient changes in cytoskeletal organization that appear to be mediated by cAMP.

  16. 8-Chloro-cyclic AMP inhibits autocrine and angiogenic growth factor production in human colorectal and breast cancer.

    PubMed

    Bianco, C; Tortora, G; Baldassarre, G; Caputo, R; Fontanini, G; Chinè, S; Bianco, A R; Ciardiello, F

    1997-03-01

    8-Chloro-cyclic AMP (8-Cl-cAMP) is a cAMP analogue that specifically down-regulates type I protein kinase A, a signaling protein directly involved in cell proliferation and neoplastic transformation, and that causes growth inhibition in a variety of human cancer cell types. In this report, we have investigated the effects of 8-Cl-cAMP on the expression of several growth factors in human colon (GEO and LS174T) and breast (MDA-MB468) cancer cell lines. 8-Cl-cAMP treatment caused in the three cancer cell lines a significant dose- and time-dependent inhibition in the expression of various endogenous autocrine growth factors, such as transforming growth factor alpha, amphiregulin, and CRIPTO, and of two angiogenic factors, such as vascular endothelial growth factor and basic fibroblast growth factor, at both the mRNA and protein levels. Furthermore, 8-Cl-cAMP treatment markedly inhibited the ability of all three cell lines to invade a basement membrane matrix in a chemoinvasion assay. Finally, 8-Cl-cAMP-induced inhibition of GEO tumor growth in nude mice was accompanied by a significant suppression of transforming growth factor alpha, amphiregulin, CRIPTO, basic fibroblast growth factor, and vascular endothelial growth factor production by the tumor cells, and of neoangiogenesis, as detected by factor VIII staining of host blood cells. These results demonstrate that 8-Cl-cAMP is a novel anticancer drug that inhibits the production of various autocrine and paracrine tumor growth factors that are important in sustaining autonomous local growth and facilitate invasion and metastasis. PMID:9815703

  17. Cyclic AMP Mediates the Direct Antiproliferative Action of Mismatched Double-Stranded RNA

    Microsoft Academic Search

    Howard R. Hubbell; John E. Boyer; Philip Roane; Ronald M. Burch

    1991-01-01

    Previous experiments have demonstrated that double-stranded RNAs (dsRNAs) can exert an antiproliferative effect on human tumor cells, independent of interferon (IFN) induction. However, the mechanism by which dsRNAs inhibit tumor growth has not been elucidated. As a first step in determining the molecular events responsible for growth arrest, we have explored the role of signal transduction through the cAMP system

  18. 8-bromo-cyclicAMP stimulates glucose transporter-1 expression in a human choriocarcinoma cell line

    Microsoft Academic Search

    K Ogura; M Sakata; Y Okamoto; Y Yasui; C Tadokoro; Y Yoshimoto; M Yamaguchi; H Kurachi; T Maeda; Y Murata

    2000-01-01

    Facilitative glucose transporter-1 (GLUT1) is abundant in trophoblast cells and is responsible for glucose transport in the placenta. However, the change in GLUT expression in human placenta upon trophoblast differentiation re- mains to be clarified. Therefore, we first examined the localization of GLUT1 and GLUT3 using human first- trimester chorionic villi. We found that GLUT1 and GLUT3 were mainly localized

  19. Cyclic AMP-mediated induction of ornithine decarboxylase of glioma and neuroblastoma cells.

    PubMed Central

    Bachrach, U

    1975-01-01

    The activity of ornithine decarboxylase (EC 4.1.1.17; L-ornithine carboxy-lyase) of C6-BU-1 glioma and N115 neuroblastoma cells increases significantly when confluent cultures are treated with compounds that increase cellular cAMP levels. These include norepinephrine or isoproterenol, and prostaglandin E1 or adenosine, which stimulate ornithine decarboxylase activity in C6-BU-1 glioma and N115 neuroblastoma cells, respectively. Ornithine decarboxylase activity is also elevated in confluent C6-BU-1 glioma cells treated with dibutyrylcAMP and theophylline, or after the glioma cells are fed with a serum-depleted medium in the presence of catecholamines and inhibitors of cyclic nucleotide phosphodiesterase. The activity of the enzyme increases 500- to 1000-fold, 2-6 hr after stationary-phase N115 neuroblastoma cells are fed with a serum-free medium, supplemented with phosphodiesterase inhibitors, adenosine, or prostaglandin E1. This stimulation is antagonized by carbamoyl choline and is blocked by actinomycin D or cycloheximide. These results suggest that the synthesis of ornithine decarboxylase of C6-BU-1 glioma and N115 neuroblastoma cells is controlled by cAMP. PMID:171652

  20. Roles of cyclic AMP in regulation of phototaxis in Chlamydomonas reinhardtii

    Microsoft Academic Search

    Maskiet Boonyareth; Jureepan Saranak; Darawan Pinthong; Yupin Sanvarinda; Kenneth W. Foster

    2009-01-01

    Chlamydomonas reinhardtii swims toward or away from light (phototaxis) in a graded way depending on various conditions. Activation of rhodopsin provides\\u000a signals to control the steering of this unicellular organism relative to a light source and to up-regulate rhodopsin biosynthesis.\\u000a Intracellular cAMP and cGMP concentrations were measured in positive (1117, swims toward light) and negative (806, swims away\\u000a from light)

  1. Cyclic AMP Mediates a Presynaptic Form of LTP at Cerebellar Parallel Fiber Synapses

    Microsoft Academic Search

    Paul A Salin; Robert C Malenka; Roger A Nicoll

    1996-01-01

    The N-methyl-D-aspartate receptor–independent form of long-term potentiation (LTP) at hippocampal mossy fiber synapses requires presynaptic Ca2+–dependent activation of adenylyl cyclase. To determine whether this form of LTP might occur at other synapses, we examined cerebellar parallel fibers that, like hippocampal mossy fiber synapses, express high levels of the Ca2+\\/calmodulin-sensitive adenylyl cyclase I. Repetitive stimulation of parallel fibers caused a long-lasting

  2. Pharmacological characterization of the dopamine receptor coupled to cyclic AMP formation expressed by rat mesenteric artery vascular smooth muscle cells in culture.

    PubMed Central

    Hall, A. S.; Bryson, S. E.; Vaughan, P. F.; Ball, S. G.; Balmforth, A. J.

    1993-01-01

    1. Mesenteric artery vascular smooth muscle cells derived from male Wistar rats and grown in culture were prelabelled with [3H]-adenine and exposed to a range of dopamine receptor agonists and antagonists. Resultant [3H]-cyclic AMP formation was determined and concentration-effect curves constructed, in the presence of propranolol (10-6) M) and the phosphodiesterase inhibitor IBMX (5 x 10(-4) M). 2. Ka apparent values for D1/DA1 dopamine receptor agonists SKF 38393, fenoldopam, 6,7-ADTN, and dopamine were 0.06, 0.59, 4.06 and 5.77 x 10(-6) M respectively. Although fenoldopam and SKF 38393 were more potent than dopamine, they were partial agonists with efficacies, relative to dopamine of approximately 48% and 24% respectively. 6,7-ADTN, in contrast, behaved as a full agonist. 3. Dopamine-stimulated cyclic AMP formation was inhibited in a concentration-dependent manner by the D1/DA1 dopamine receptor selective antagonists, SCH 23390 and cis-flupenthixol (Ki values 0.53 and 36.1 x 10(-1) M respectively). In contrast, the D2/DA2 dopamine receptor selective antagonists, domperidone and (-)-sulpiride, were less potent (Ki values 2.06 and 5.82 x 10(-6) M respectively). Furthermore, the stereoisomers of SCH 23390 and cis-flupenthixol, SCH 23388 and trans-flupenthixol, were at least two orders of magnitude less potent (Ki values 0.14 and 13.2 x 10(-6) M respectively) indicating the stereoselective nature of this receptor. 4. Our results indicate that rat mesenteric artery vascular smooth muscle cells in culture express a dopamine receptor coupled to cyclic AMP formation, which has the pharmacological profile, characteristic of the D1 dopamine receptor subfamily. PMID:7902178

  3. An Odor-Specific Threshold Deficit Implicates Abnormal Intracellular Cyclic AMP Signaling in Schizophrenia

    PubMed Central

    Turetsky, Bruce I.; Moberg, Paul J.

    2012-01-01

    Objective Although olfactory deficits are common in schizophrenia, their underlying pathophysiology remains unknown. Recent evidence has suggested that cAMP signaling may be disrupted in schizophrenia. Since cAMP mediates signal transduction in olfactory receptor neurons, this could contribute to the etiology of observed olfactory deficits. This study was designed to test this hypothesis by determining odor detection threshold sensitivities to two odorants that differ in their relative activations of this intracellular cAMP signaling cascade. Method Thirty schizophrenia patients, 25 healthy comparison subjects, and 19 unaffected first-degree relatives of schizophrenia patients were studied. Odor detection threshold sensitivities were measured for the two odorants citralva and lyral. Although both have fruity/floral scents, citralva strongly activates adenylyl cyclase to increase cAMP levels, while lyral is a very weak activator of adenylyl cyclase. Results There was a significant group-by-odor interaction. Both schizophrenia patients and unaffected first-degree relatives were impaired in their ability to detect lyral versus citralva. Comparison subjects were equally sensitive to both odorants. This selective deficit could not be explained by differences in age, sex, smoking, clinical symptom profile, or medication use. Conclusions This study establishes the presence of an odor-specific hyposmia that may denote a disruption of cAMP-mediated signal transduction in schizophrenia. The presence of a parallel deficit in the patients’ unaffected first-degree relatives suggests that this deficit is genetically mediated. Although additional physiological studies are needed to confirm the underlying mechanism, these results offer strong inferential support for the hypothesis that cAMP signaling is dys-regulated in schizophrenia. PMID:19074977

  4. Ezrin is a cyclic AMP-dependent protein kinase anchoring protein.

    PubMed Central

    Dransfield, D T; Bradford, A J; Smith, J; Martin, M; Roy, C; Mangeat, P H; Goldenring, J R

    1997-01-01

    cAMP-dependent protein kinase (A-kinase) anchoring proteins (AKAPs) are responsible for the subcellular sequestration of the type II A-kinase. Previously, we identified a 78 kDa AKAP which was enriched in gastric parietal cells. We have now purified the 78 kDa AKAP to homogeneity from gastric fundic mucosal supernates using type II A-kinase regulatory subunit (RII) affinity chromatography. The purified 78 kDa AKAP was recognized by monoclonal antibodies against ezrin, the canalicular actin-associated protein. Recombinant ezrin produced in either Sf9 cells or bacteria also bound RII. Recombinant radixin and moesin, ezrin-related proteins, also bound RII in blot overlay. Analysis of recombinant truncations of ezrin mapped the RII binding site to a region between amino acids 373 and 439. This region contained a 14-amino-acid amphipathic alpha-helical putative RII binding region. A synthetic peptide containing the amphipathic helical region (ezrin409-438) blocked RII binding to ezrin, but a peptide with a leucine to proline substitution at amino acid 421 failed to inhibit RII binding. In mouse fundic mucosa, RII immunoreactivity redistributed from a predominantly cytosolic location in resting parietal cells, to a canalicular pattern in mucosa from animals stimulated with gastrin. These results demonstrate that ezrin is a major AKAP in gastric parietal cells and may function to tether type II A-kinase to a region near the secretory canaliculus. PMID:9009265

  5. Cyclic AMP and c-KIT Signaling in Familial Testicular Germ Cell Tumor Predisposition

    PubMed Central

    Azevedo, Monalisa F.; Horvath, Anelia; Bornstein, Ethan R.; Almeida, Madson Q.; Xekouki, Paraskevi; Faucz, Fabio R.; Gourgari, Evgenia; Nadella, Kiran; Remmers, Elaine F.; Quezado, Martha; de Alexandre, Rodrigo Bertollo; Kratz, Christian P.; Nesterova, Maria; Greene, Mark H.

    2013-01-01

    Background: Familial testicular germ cell tumors (FTGCTs) are hypothesized to result from the combined interaction of multiple low-penetrance genes. We reported inactivating germline mutations of the cAMP-binding phosphodiesterase 11A (PDE11A) as modifiers of FTGCT risk. Recent genome-wide association studies have identified single-nucleotide polymorphisms in the KITLG gene, the ligand for the cKIT tyrosine kinase receptor, as strong modifiers of susceptibility to both familial and sporadic testicular germ cell tumors. Design: We studied 94 patients with FTGCTs and 50 at-risk male relatives from 63 unrelated kindreds, in whom the PDE11A gene had been sequenced by investigating the association between KITLG genome-wide association study single-nucleotide polymorphisms rs3782179 and rs4474514 and FTGCT risk in these patients and in 692 controls. We also examined cAMP and c-KIT signaling in testicular tissues and cell lines and extended the studies to 2 sporadic cases, one with a PDE11A defect and one without, as a comparison. Results: We found a higher frequency of the KITLG risk alleles in FTGCT patients who also had a PDE11A sequence variant, compared with those with a wild-type PDE11A sequence. In NTERA-2 and Tcam-2 cells transfected with the mutated forms of PDE11A (R52T, F258Y, Y727C, R804H, V820M, R867G, and M878V), cAMP levels were significantly higher, and the relative phosphodiesterase activity was lower than in the wild-type cells. KITLG expression was consistently increased in the presence of PDE11A-inactivating defects, both at the RNA and protein levels, in familial testicular germ cell tumors. The 2 sporadic cases that were studied, one with a PDE11A defect and another without, agreed with the data in FTGTCT and in the cell lines. Conclusions: Patients with FTGCT and PDE11A defects also carry KITLG risk alleles more frequently. There may be an interaction between cAMP and c-KIT signaling in predisposition to testicular germ cell tumors. PMID:23771924

  6. The cyclic AMP-dependent protein kinase catalytic subunit selectively enhances calcium currents in rat nodose neurones.

    PubMed Central

    Gross, R A; Uhler, M D; Macdonald, R L

    1990-01-01

    1. The whole-cell variation of the patch clamp technique was used to study the effect of the purified catalytic subunit of the cyclic AMP-dependent protein kinase (A kinase catalytic subunit: AK-C) on the calcium current components of acutely dissociated rat nodose ganglion neurones. 2. The transient low-threshold calcium current component (T) was stable during whole-cell recording. In contrast, currents containing the transient high-threshold (N) and slowly inactivating high-threshold (L) current components declined steadily after stabilization of the currents during the first 5-7 min of recording. When AK-C was included in the recording pipette at physiological concentrations (50 micrograms/ml, approximately 1 microM), currents containing the N- and L-components increased in magnitude beginning 7-9 min after patch rupture, but there was no effect on the isolated T-current. The current-voltage relation of the T-current component was similar to controls, but the current-voltage relation for the N- and L-current components was shifted slightly to more depolarized clamp potentials (Vc), approximately 10 mV. 3. The effect of AK-C on currents containing the N- and L-currents was concentration dependent. There was no effect of 0.1 microgram/ml AK-C, the lowest concentration tested. Currents evoked from holding potentials (Vh) = -80 mV increased 5-10% during a 20 min recording in the presence of 1 microgram/ml AK-C and 30-35% in the presence of 50 micrograms/ml AK-C. In contrast, currents evoked from Vh = -40 mV increased 5-10% in the presence of either 1 or 50 micrograms/ml AK-C. The increase in current magnitude was associated with an increased rate of current inactivation and was evident particularly in currents evoked from Vh = -80 mV. 4. These effects were blocked by prior incubation of AK-C (1 microgram/ml) with a specific peptide inhibitor (protein kinase inhibitor peptide, PKIP; 0.2 mg/ml). 5. We evoked calcium currents using very long (1 s) voltage commands and modelled the traces using a multiexponential function in order to determine the effects of AK-C on the N- and L-current components. The (curve-fitted) N- and L-current components each declined approximately 50% during a 20 min recording in control neurones.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2177506

  7. Phosphorylation of SOX9 by Cyclic AMP-Dependent Protein Kinase A Enhances SOX9's Ability To Transactivate a Col2a1 Chondrocyte-Specific Enhancer

    PubMed Central

    Huang, Wendong; Zhou, Xin; Lefebvre, Véronique; de Crombrugghe, Benoit

    2000-01-01

    Sox9 is a high-mobility-group domain-containing transcription factor required for chondrocyte differentiation and cartilage formation. We used a yeast two-hybrid method based on Son of Sevenless (SOS) recruitment to screen a chondrocyte cDNA library and found that the catalytic subunit of cyclic AMP (cAMP)-dependent protein kinase A (PKA-C?) interacted specifically with SOX9. Next we found that two consensus PKA phosphorylation sites within SOX9 could be phosphorylated by PKA in vitro and that SOX9 could be phosphorylated by PKA-C? in vivo. In COS-7 cells cotransfected with PKA-C? and SOX9 expression plasmids, PKA enhanced the phosphorylation of wild-type SOX9 but did not affect phosphorylation of a SOX9 protein in which the two PKA phosphorylation sites (S64 and S211) were mutated. Using a phosphospecific antibody that specifically recognized SOX9 phosphorylated at serine 211, one of the two PKA phosphorylation sites, we demonstrated that addition of cAMP to chondrocytes strongly increased the phosphorylation of endogenous Sox9. In addition, immunohistochemistry of mouse embryo hind legs showed that Sox9 phosphorylated at serine 211 was principally localized in the prehypertrophic zone of the growth plate, corresponding to the major site of expression of the parathyroid hormone-related peptide (PTHrP) receptor. Since cAMP has previously been shown to effectively increase the mRNA levels of Col2a1 and other specific markers of chondrocyte differentiation in culture, we then asked whether PKA phosphorylation could modulate the activity of SOX9. Addition of 8-bromo-cAMP to chondrocytes in culture increased the activity of a transiently transfected SOX9-dependent 48-bp Col2a1 chondrocyte-specific enhancer; similarly, cotransfection of PKA-C? increased the activity of this enhancer. Mutations of the two PKA phosphorylation consensus sites of SOX9 markedly decreased the PKA-C? activation of this enhancer by SOX9. PKA phosphorylation and the mutations in the consensus PKA phosphorylation sites of SOX9 did not alter its nuclear localization. In vitro phosphorylation of SOX9 by PKA resulted in more efficient DNA binding. We conclude that SOX9 is a target of cAMP signaling and that phosphorylation of SOX9 by PKA enhances its transcriptional and DNA-binding activity. Because PTHrP signaling is mediated by cAMP, our results support the hypothesis that Sox9 is a target of PTHrP signaling in the growth plate and that the increased activity of Sox9 might mediate the effect of PTHrP in maintaining the cells as nonhypertrophic chondrocytes. PMID:10805756

  8. Role of platelet activating factor in the intestinal epithelial secretory and Chinese hamster ovary cell cytoskeletal responses to cholera toxin.

    PubMed Central

    Guerrant, R L; Fang, G D; Thielman, N M; Fonteles, M C

    1994-01-01

    With the recent heightened concern about cholera around the world come new questions about the mechanism by which cholera toxin causes diarrhea. Peterson and Ochoa have suggested that prostaglandin synthesis is key to both the intestinal epithelial secretory and the CHO cell responses to cholera toxin [Peterson, J. W. and Ochoa, G. (1989) Science 245, 857-859]. Because platelet activating factor (PAF) can be a potent stimulus for prostaglandin synthesis, we examined its role in the intestinal and tissue culture effects of cholera toxin. We report that the specific PAF receptor antagonists BN 52021 and SR 27417 inhibit the effects of cholera toxin on intestinal secretion in rabbit ileal loops in vivo and on the cytoskeleton of Chinese hamster ovary cells in vitro. We also show that PAF itself can cause net fluid secretion in the rabbit model and that PAF potentiates the effects of cholera toxin on intestinal secretion. Finally, we demonstrate that cholera toxin stimulates significant PAF production (2.6-fold) in isolated T-84 intestinal epithelial cells. We conclude that cholera toxin stimulates PAF production and that PAF is involved in both the secretory and cytoskeletal responses to cholera toxin. These findings further support the involvement of additional mediators of cholera toxin effects other than mucosal cell cyclic AMP and help explain the effects of cholera toxin on prostaglandin synthesis. PMID:7937824

  9. Differential Regulation of Human 3?-Hydroxysteroid Dehydrogenase Type 2 for Steroid Hormone Biosynthesis by Starvation and Cyclic Amp Stimulation: Studies in the Human Adrenal NCI-H295R Cell Model

    PubMed Central

    Hofer, Gaby; Mullis, Primus E.; Flück, Christa E.

    2013-01-01

    Human steroid biosynthesis depends on a specifically regulated cascade of enzymes including 3?-hydroxysteroid dehydrogenases (HSD3Bs). Type 2 HSD3B catalyzes the conversion of pregnenolone, 17?-hydroxypregnenolone and dehydroepiandrosterone to progesterone, 17?-hydroxyprogesterone and androstenedione in the human adrenal cortex and the gonads but the exact regulation of this enzyme is unknown. Therefore, specific downregulation of HSD3B2 at adrenarche around age 6–8 years and characteristic upregulation of HSD3B2 in the ovaries of women suffering from the polycystic ovary syndrome remain unexplained prompting us to study the regulation of HSD3B2 in adrenal NCI-H295R cells. Our studies confirm that the HSD3B2 promoter is regulated by transcription factors GATA, Nur77 and SF1/LRH1 in concert and that the NBRE/Nur77 site is crucial for hormonal stimulation with cAMP. In fact, these three transcription factors together were able to transactivate the HSD3B2 promoter in placental JEG3 cells which normally do not express HSD3B2. By contrast, epigenetic mechanisms such as methylation and acetylation seem not involved in controlling HSD3B2 expression. Cyclic AMP was found to exert differential effects on HSD3B2 when comparing short (acute) versus long-term (chronic) stimulation. Short cAMP stimulation inhibited HSD3B2 activity directly possibly due to regulation at co-factor or substrate level or posttranslational modification of the protein. Long cAMP stimulation attenuated HSD3B2 inhibition and increased HSD3B2 expression through transcriptional regulation. Although PKA and MAPK pathways are obvious candidates for possibly transmitting the cAMP signal to HSD3B2, our studies using PKA and MEK1/2 inhibitors revealed no such downstream signaling of cAMP. However, both signaling pathways were clearly regulating HSD3B2 expression. PMID:23874725

  10. Cyclic AMP stimulates platelet-derived growth factor B chain mRNA expression in murine macrophage cell lines

    PubMed Central

    VanStedum, Susan

    1995-01-01

    Prostaglandin E2 plays a role in cytokine production presumably by altering intracellular levels of cAMP. In this paper, we report on the differential expression of cytokine genes in murine macrophages in response to stimulation with activators of cAMP. Macrophages were cultured with or without cAMP activators in the presence or absence of LPS. Prior to treatment, macrophages do not express interleukin-1?, but do express low levels of tumour necrosis factor ? and platelet-derived growth factor B chain mRNAs. After culture with cAMP-inducers, including PGE2, dibutyryl cAMP and forskolin, PDGF B chain mRNA is induced. Forskolin, for example, induced expression PDGF B chain mRNA to a level ranging from 25% to 200% of the level induced by LPS in 6 h. In contrast, cAMP-inducers enhance the expression of IL-1? and TNF-? mRNAs, but only in the presence of LPS. The combination of forskolin and LPS does not appear to act synergistically on PDGF B chain mRNA levels, suggesting that LPS-stimulated effects are not mediated through a cAMP-dependent pathway. Furthermore, macrophages differentially express cytokine genes in response to treatment with inducers of intracellular cAMP. PMID:18475654

  11. Intracellular events mediating insulin-like growth factor I-induced oligodendrocyte development: modulation by cyclic AMP.

    PubMed

    Palacios, Nuria; Sánchez-Franco, Franco; Fernández, Miriam; Sánchez, Isabel; Cacicedo, Lucinda

    2005-11-01

    Insulin-like growth factor I (IGF-I) is a potent inducer of oligodendrocyte development and myelination. Although IGF-I intracellular signaling has been well described in several cell types, intracellular mechanisms for IGF-I-induced oligodendrocyte development have not been defined. By using specific inhibitors of intracellular signaling pathways, we report here that the MAPK and phosphatidylinositol 3-kinase signaling pathways are required for the full effect of IGF-I on oligodendrocyte development in primary mixed rat cerebrocortical cell cultures. The MAPK activation, but not the phosphatidylinositol 3-kinase activation, leads to phosphorylation of the cAMP response element-binding protein, which is necessary for IGF-I to induce oligodendrocyte development. cAMP, although it does not show any effect on oligodendrocyte development, has an inhibitory effect on IGF-I-induced oligodendrocyte development that is mediated by the cAMP-dependent protein kinase. Furthermore, cAMP also has an inhibitory effect on IGF-I-dependent MAPK activation. This is a cAMP-dependent protein kinase-independent effect and probably contributes to the cAMP action on IGF-I-induced oligodendrocyte development. PMID:16271046

  12. Effect of beta-ADrenergic Agonist on Cyclic AMP Synthesis in Chicken Skeletal Muscle Cells in Culture

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Bridge, K. Y.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Because it seems logical that these agonists exert their action on muscle through stimulation of cAMP synthesis, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax levels were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. In addition, the EC50 values for isoproterenol, cimaterol, clenbuterol, epinephrine, and albuterol were 360 nM, 630 nM, 900 nM, 2,470 nM, and 3,650 nM, respectively. Finally, dose response curves show that the concentrations of cimaterol and clenbuterol in culture media at concentrations known to cause significant muscle hypertrophy in animals had no detectable effect on stimulation of CAMP accumulation in chicken skeletal muscle cells.

  13. Cyclic AMP directs inositol (1,4,5)-trisphosphate-evoked Ca2+ signalling to different intracellular Ca2+ stores

    PubMed Central

    Tovey, Stephen C.; Taylor, Colin W.

    2013-01-01

    Summary Cholesterol depletion reversibly abolishes carbachol-evoked Ca2+ release from inositol (1,4,5)-trisphosphate (IP3)-sensitive stores, without affecting the distribution of IP3 receptors (IP3R) or endoplasmic reticulum, IP3 formation or responses to photolysis of caged IP3. Receptors that stimulate cAMP formation do not alone evoke Ca2+ signals, but they potentiate those evoked by carbachol. We show that these potentiated signals are entirely unaffected by cholesterol depletion and that, within individual cells, different IP3-sensitive Ca2+ stores are released by carbachol alone and by carbachol combined with receptors that stimulate cAMP formation. We suggest that muscarinic acetylcholine receptors in lipid rafts deliver IP3 at high concentration to associated IP3R, stimulating them to release Ca2+. Muscarinic receptors outside rafts are less closely associated with IP3R and provide insufficient local IP3 to activate IP3R directly. These IP3R, probably type 2 IP3R within a discrete Ca2+ store, are activated only when their sensitivity is increased by cAMP. Sensitization of IP3R by cAMP extends the effective range of signalling by phospholipase C, allowing muscarinic receptors that are otherwise ineffective to recruit additional IP3-sensitive Ca2+ stores. PMID:23525004

  14. Engineers and Active Responsibility.

    PubMed

    Pesch, Udo

    2014-07-01

    Knowing that technologies are inherently value-laden and systemically interwoven with society, the question is how individual engineers can take up the challenge of accepting the responsibility for their work? This paper will argue that engineers have no institutional structure at the level of society that allows them to recognize, reflect upon, and actively integrate the value-laden character of their designs. Instead, engineers have to tap on the different institutional realms of market, science, and state, making their work a 'hybrid' activity combining elements from the different institutional realms. To deal with this institutional hybridity, engineers develop routines and heuristics in their professional network, which do not allow societal values to be expressed in a satisfactory manner. To allow forms of 'active' responsibility, there have to be so-called 'accountability forums' that guide moral reflections of individual actors. The paper will subsequently look at the methodologies of value-sensitive design (VSD) and constructive technology assessment (CTA) and explore whether and how these methodologies allow engineers to integrate societal values into the design technological artifacts and systems. As VSD and CTA are methodologies that look at the process of technological design, whereas the focus of this paper is on the designer, they can only be used indirectly, namely as frameworks which help to identify the contours of a framework for active responsibility of engineers. PMID:25005341

  15. Functional Similarities between the Listeria monocytogenes Virulence Regulator PrfA and Cyclic AMP Receptor Protein: the PrfA* (Gly145Ser) Mutation Increases Binding Affinity for Target DNA

    PubMed Central

    Vega, Yolanda; Dickneite, Carmen; Ripio, María-Teresa; Böckmann, Regine; González-Zorn, Bruno; Novella, Susana; Domínguez-Bernal, Gustavo; Goebel, Werner; Vázquez-Boland, José A.

    1998-01-01

    Most Listeria monocytogenes virulence genes are positively regulated by the PrfA protein, a transcription factor sharing sequence similarities with cyclic AMP (cAMP) receptor protein (CRP). Its coding gene, prfA, is regulated by PrfA itself via an autoregulatory loop mediated by the upstream PrfA-dependent plcA promoter. We have recently characterized prfA* mutants from L. monocytogenes which, as a result of a single amino acid substitution in PrfA, Gly145Ser, constitutively overexpress prfA and the genes of the PrfA virulence regulon. Here, we show that about 10 times more PrfA protein is produced in a prfA* strain than in the wild type. Thus, the phenotype of prfA* mutants is presumably due to the synthesis of a PrfA protein with higher promoter-activating activity (PrfA*), which keeps its intracellular levels constantly elevated by positive feedback. We investigated the interaction of PrfA and PrfA* (Gly145Ser) with target DNA. Gel retardation assays performed with a DNA fragment carrying the PrfA binding site of the plcA promoter demonstrated that the PrfA* mutant form is much more efficient than wild-type PrfA at forming specific DNA-protein complexes. In footprinting experiments, the two purified PrfA forms interacted with the same nucleotides at the target site, although the minimum amount required for protection was 6 to 7 times lower with PrfA*. These results show that the primary functional consequence of the Gly145Ser mutation is an increase in the affinity of PrfA for its target sequence. Interestingly, similar mutations at the equivalent position in CRP result in a transcriptionally active, CRP* mutant form which binds with high affinity to target DNA in the absence of the activating cofactor, cAMP. Our observations suggest that the structural similarities between PrfA and CRP are also functionally relevant and support a model in which the PrfA protein, like CRP, shifts from transcriptionally inactive to active conformations by interaction with a cofactor. PMID:9852011

  16. Effect of Increased Cyclic AMP Concentration on Muscle Protein Synthesis and Beta-Adrenergic Receptor Expression in Chicken Skeletal Muscle Cells in Culture

    NASA Technical Reports Server (NTRS)

    Young, R. B.; Vaughn, J. R.; Bridge, K. Y.; Smith, C. K.

    1998-01-01

    Analogies of epinephrine are known to cause hypertrophy of skeletal muscle when fed to animals. These compounds presumably exert their physiological action through interaction with the P-adrenergic receptor. Since the intracellular signal generated by the Beta-adrenergic receptor is cyclic AMP (cAMP), experiments were initiated in cell culture to determine if artificial elevation of cAMP by treatment with forskolin would alter muscle protein metabolism and P-adrenergic receptor expression. Chicken skeletal muscle cells after 7 days in culture were treated with 0.2-30 micrometers forskolin for a total of three days. At the end of the treatment period, both the concentration of cAMP and the quantity of myosin heavy chain (MHC) were measured. Concentration of cAMP in forskolin-treated cells increased up to 10-fold in a dose dependent manner. In contrast, the quantity of MHC was increased approximately 50% above control cells at 0.2 micrometers forskolin, but exhibited a gradual decline at higher levels of forskolin so that the quantity of MHC in cells treated with 30 micrometers forskolin was not significantly different from controls. Curiously, the intracellular concentration of cAMP which elicited the maximum increase in the quantity of MHC was only 40% higher than cAMP concentration in control cells.

  17. Forskolin: unique diterpene activator of adenylate cyclase in membranes and in intact cells.

    PubMed Central

    Seamon, K B; Padgett, W; Daly, J W

    1981-01-01

    The diterpene, forskolin [half-maximal effective concentration (EC50), 5-10 microM] activates adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] in rat cerebral cortical membranes in a rapid and reversible manner. Activation is not dependent on exogenous guanyl nucleotides and is not inhibited by guanosine 5'-O-(2-thiodiphosphate) when assayed with adenosine 5'-[beta, gamma-imido]triphosphate as substrate. GTP and GDP potentiate responses to forskolin. The activations of adenylate cyclase by forskolin and guanosine 5'-[beta, gamma-imido]triphosphate p[NH]ppG are not additive, whereas activations by forskolin and fluoride are additive or partially additive. The responses of adenylate cyclase to forskolin or fluoride are not inhibited by manganese ions, whereas the response to p[NH]ppG is completely blocked. Activation of adenylate cyclase by forskolin is considerably greater than the activation by fluoride in membranes from rat cerebellum, striatum, heart, and liver, while being about equal or less than the activation by fluoride in other tissues. Forskolin (EC50, 25 microM) causes a rapid and readily reversible 35-fold elevation of cyclic AMP in rat cerebral cortical slices that is not blocked by a variety of neurotransmitter antagonists. Low concentrations of forskolin (1 microM) augment the response of cyclic AMP-generating systems in brain slices to norepinephrine, isoproterenol, histamine, adenosine, prostaglandin E2, and vasoactive intestinal peptide. Forskolin would appear to activate adenylate cyclase through a unique mechanism involving both direct activation of the enzyme and facilitation or potentiation of the modulation of enzyme activity by receptors or the guanyl nucleotide-binding subunit, or both. PMID:6267587

  18. Effect of adenylate cyclase stimulation on meiotic resumption and cyclic AMP content of zona-free and cumulus-enclosed bovine oocytes in vitro.

    PubMed

    Bilodeau, S; Fortier, M A; Sirard, M A

    1993-01-01

    The effect of adenylate cyclase stimulation via the components of the enzyme on nuclear maturation in bovine cumulus-enclosed and zona-free oocytes was examined. The stimulating agents were cholera toxin, pertussis toxin, forskolin, sodium fluoride and prostaglandin E2. Cyclic AMP contents were measured in cumulus-oocyte complexes, cumulus-enclosed oocytes and in zona-free oocytes after stimulation, to establish the relationship between cumulus cell and oocyte cAMP concentrations and the meiotic status of the oocyte. In cumulus-enclosed oocytes, forskolin alone and 3-isobutyl-1-methylxanthine (IBMX), at 0.5 mmol l-1, inhibited the resumption of meiosis after 8 h of culture; the other agents were without effect. After 24 h of culture, IBMX at 0.5 mmol l-1 was without effect, but at 2 mmol l-1 reduced the percentage of oocytes at the mature stage (51 versus 82% in control medium). Forskolin alone reduced the proportion of oocytes at the mature stage from 82 to 58%. Forskolin plus IBMX at 2 mmol l-1 and sodium fluoride plus IBMX at 2 mmol l-1 significantly diminished the maturation rate (6 and 17% mature oocytes, respectively). Cholera toxin (with IBMX) and forskolin (alone or with IBMX) stimulated the synthesis of high amounts of cAMP in complexes, but only forskolin had a significant effect on the cAMP contents of oocytes derived from complexes. Forskolin was more effective in zona-free oocytes than in cumulus-enclosed oocytes in inhibiting nuclear maturation (24% mature oocytes versus 73% in control medium) even after 24 h of culture; its effect was potentiated by IBMX; forskolin also stimulated cAMP synthesis.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7681878

  19. Cloning and nucleotide sequence of the cyclic AMP receptor protein-regulated Salmonella typhimurium pepE gene and crystallization of its product, an alpha-aspartyl dipeptidase.

    PubMed Central

    Conlin, C A; Håkensson, K; Liljas, A; Miller, C G

    1994-01-01

    The Salmonella typhimurium pepE gene, encoding an N-terminal-Asp-specific dipeptidase, has been cloned on pBR328 by complementation of the Asp-Pro growth defect conferred by a pepE mutation. Strains carrying the complementing plasmids greatly overproduce peptidase E. The enzyme has been purified from an extract of such a strain, its N-terminal amino acid sequence has been determined, and crystals suitable for X-ray diffraction have been grown. A new assay using L-aspartic acid p-nitroanilide as a substrate has been used to determine the pH optimum (approximately 7.5) and to test the effect of potential inhibitors. Insertions of transposon gamma delta (Tn1000) into one of the plasmids have been used to localize the gene and as sites for priming sequencing reactions. The nucleotide sequence of a 1,088-bp region of one of these plasmids has been determined. This sequence contains an open reading frame that predicts a 24.8-kDa protein with an N-terminal sequence that agrees with that determined for peptidase E. The predicted peptidase E amino acid sequence is not similar to that of any other known protein. The nucleotide sequence of the region upstream from pepE contains a promoter with a cyclic AMP receptor protein (CRP) site, and the effects of growth medium and of a crp mutation on expression of a pepE-lacZ fusion indicate that pepE is a member of the CRP regulon. The unique specificity of peptidase E and its lack of sequence similarity to any other peptidase suggest that this enzyme may be the prototype of a new class of peptidases. Its regulation by CPR and its specificity suggest that the enzyme may play a role in allowing the cell to use peptide aspartate to spare carbon otherwise required for the synthesis of the aspartate family of amino acids. PMID:8282693

  20. Beta-Adrenergic Receptor Population is Up-Regulated by Increased Cyclic Amp Concentration in Chicken Skeletal Muscle Cells in Culture

    NASA Technical Reports Server (NTRS)

    Young, Ronald B.; Bridge, Kristin Y.; Vaughn, Jeffrey R.

    1999-01-01

    Skeletal muscle hypertrophy is promoted in vivo by administration of beta-drenergic receptor (bAR) agonists. Chicken skeletal muscle cells were treated with 1 (mu)M isoproterenol, a strong bAR agonist, between days 7 and 10 in culture. bAR population increased by approximately 40% during this treatment; however, the ability of the cells to synthesize cyclic AMP (cAMP) was diminished by two-fold. The quantity of myosin heavy chain (MHC) was not affected. To understand further the relationship between intracellular cAMP levels, bAR population, and muscle protein accumulation, intracellular cAMP levels were artificially elevated by treatment with 0-10 uM forskolin for up to three days. The basal concentration of CAMP in forskolin-treated cells increased up to 7-fold in a dose dependent manner. Increasing concentrations of forskolin also led to an increase in bAR population, with a maximum increase of approximately 40-60% at 10 uM forskolin. A maximum increase of 40-50% in the quantity of MHC was observed at 0.2 uM forskolin, but higher concentrations of forskolin reduced the quantity of MHC back to control levels. At 0.2 uM forskolin, intracellular levels of cAMP were higher by approximately 35%, and the (beta)AR population was higher by approximately 30%. Neither the number of muscle nuclei fused into myotubes nor the percentage of nuclei in myotubes were affected by forskolin at any of the concentrations studied.

  1. Cyclic AMP-dependent protein kinase A negatively regulates conidia formation by the tangerine pathotype of Alternaria alternata.

    PubMed

    Tsai, Hsieh-Chin; Yang, Siwy Ling; Chung, Kuang-Ren

    2013-02-01

    The necrotrophic fungal pathogen Alternaria alternata causes brown spot diseases in many citrus cultivars. The FUS3 and SLT2 mitogen-activated protein kinases (MAPK)-mediated signaling pathways have been shown to be required for conidiation. Exogenous application of cAMP to this fungal pathogen decreased conidia formation considerably. This study determined whether a cAMP-activated protein kinase A (PKA) is required for conidiation. Using loss-of-function mutations in PKA catalytic and regulatory subunit-coding genes, we demonstrated that PKA negatively regulates conidiation. Fungal mutants lacking PKA catalytic subunit gene (PKA ( cat )) reduced growth, lacked detectable PKA activity, and produced higher amounts of conidia compared to wild-type. Introduction of a functional copy of PKA ( cat ) into a null mutant partially restored PKA activity and produced wild-type level of conidia. In contrast, fungi lacking PKA regulatory subunit gene (PKA ( reg )) produced detectable PKA activity, exhibited severe growth reduction, formed swelling hyphal segments, and produced no mature conidia. Introduction of the PKA ( reg ) gene to a regulatory subunit mutant restored all phenotypes to wild type. PKA ( reg )-null mutants induced fewer necrotic lesions on citrus compared to wild-type, whereas PKA ( cat ) mutant displayed wild-type virulence. Overall, our studies indicate that PKA and FUS3-mediated signaling pathways apparently have very different roles in the regulation of conidia production and A. alternata pathogenesis in citrus. PMID:23054702

  2. Intracellular signaling in the regulation of renal Na-K-ATPase. I. Role of cyclic AMP and phospholipase A2.

    PubMed Central

    Satoh, T; Cohen, H T; Katz, A I

    1992-01-01

    We have reported that dopamine (DA) inhibits Na-K-ATPase activity in the cortical collecting duct (CCD) by stimulating the DA1 receptor, and the present study was designed to evaluate the mechanism of this effect. Short-term exposure (15-30 min) of microdissected rat CCD to DA, a DA1 agonist (fenoldopam), vasopressin (AVP), forskolin, or dibutyryl cAMP (dBcAMP), which increase cAMP content by different mechanisms, strongly (approximately 60%) inhibited Na-K-ATPase activity. 2',5'-dideoxyadenosine, an inhibitor of adenylate cyclase, completely blocked Na-K-ATPase inhibition by DA or fenoldopam, and IP20, an inhibitor peptide of cAMP-dependent protein kinase A (PKA), abolished the Na:K pump effect of all the cAMP agonists listed above. To verify whether the mechanism of pump inhibition by agents that increase cell cAMP involves phospholipase A2 (PLA2), we used mepacrine, a PLA2 inhibitor, which also abolished Na-K-ATPase inhibition by DA or fenoldopam, as well as by AVP, forskolin, or dBcAMP. Arachidonic acid (10(-7) - 10(-4) M) inhibited Na-K-ATPase activity in dose-dependent fashion. Corticosterone, which induces lipomodulin, a PLA2 inhibitor protein inactivated by PKA, equally abolished the pump effects of DA, fenoldopam, forskolin, and dBcAMP, suggesting that lipomodulin might act between PKA and PLA2 in cAMP-dependent pump regulation. We conclude that dopamine inhibits Na-K-ATPase activity in the CCD through a DA1 receptor-mediated cAMP-PKA pathway that involves the stimulation of PLA2 and arachidonic acid release, possibly mediated by inactivation of lipomodulin. This pathway is shared by other agonists that increase cell cAMP and thus stimulate PKA activity. PMID:1349027

  3. Boron and silicon: Effects on growth, plasma lipids, urinary cyclic AMP and bone and brain mineral composition of male rats

    SciTech Connect

    Seaborn, C.D.; Nielsen, F.H. (Dept. of Agriculture, Grand Forks, ND (United States). Grand Forks Human Nutrition Research Center)

    1994-06-01

    Because boron resembles silicon in its chemical properties, an experiment was performed to determine if excessive dietary boron would affect the response to silicon deprivation and, conversely, if silicon would influence the effects of an excessive intake of boron. Male weanling Sprague-Dawley rats were assigned to groups of 6 or 12 in a two-by-two factorially arranged experiment. Supplemented to a ground corn/casein diet containing 1.2 [mu]g silicon and 3 [mu]g boron per gram were silicon as sodium metasilicate at 0 or 50 [mu]g/g and boron as orthoboric acid at 0 or 500 [mu]g/g diet. At nine weeks, animals fed high dietary boron had significantly decreased final body weights, liver-weight-to-body-weight ratios, urinary cAMP concentrations, plasma triglyceride, cholesterol, glycine, valine, leucine, and lysine concentrations and skull copper, sodium, and manganese concentrations. High dietary boron also significantly increased brain-weight-to-body-weight ratios, magnesium concentrations of femur, brain, and plasma, zinc concentration of femur, and iron concentration of skull. The bone mineral findings suggest that excess dietary boron exerts subtle effects on bone composition. Dietary silicon affected blood urea nitrogen, hematocrit, hemoglobin, and the concentrations of plasma threonine and aspartic acid in animals fed excess boron. Depression of the testes-weight-to-body-weight ratio of animals fed 500 [mu]g boron per gram diet was most marked in animals not fed silicon. Although excessive dietary boron did not markedly enhanced the response of rats to silicon deprivation, dietary silicon affected their response to high dietary boron. Thus, dietary silicon apparently can influence boron toxicity.

  4. A deficiency in cyclic AMP results in pH-sensitive growth of Escherichia coli K-12.

    PubMed Central

    Ahmad, D; Newman, E B

    1988-01-01

    Mutants of Escherichia coli K-12 deficient in adenyl cyclase (cya) and catabolite activator protein (crp) have been shown to grow more slowly than their parent strains in glucose-minimal medium. Their growth rate decreased markedly with increasing pH between 6 and 7.8. We have shown that this pH sensitivity is a direct consequence of the cya mutation, because a mutation to pH resistance also restored ability to ferment a variety of sugars. The proton motive force-dependent uptake of proline and glutamate was also reduced and sensitive to pH in the cya mutant. The membrane-bound ATPase activity was normal. The rate of oxygen uptake by cells, although reduced, was pH insensitive. We suggest several explanations for this phenotype, including a possible defect in energy transduction. PMID:2841287

  5. Regulation of Na + \\/H + exchange in opossum kidney cells by parathyroid hormone, cyclic AMP and phorbol esters

    Microsoft Academic Search

    Corinna Helmle-Kolb; Marshall Ho Montrose; Gerti Stange; Heini Murer

    1990-01-01

    Parathyroid hormone (PTH) controls two proximal tubular brush border membrane transport systems, Na+\\/phosphate co-transport and Na+\\/H+ exchange. In OK cells, a cell line with proximal tubular transport characteristics, PTH acts via kinase C and kinase A activation to inhibit Na+\\/phosphate co-transport [6, 8, 9, 19, 22]. In the present study, we show that PTH inhibits Na+\\/H+ exchange and that this

  6. Prolyl hydroxylase domain protein 2 regulates the intracellular cyclic AMP level in cardiomyocytes through its interaction with phosphodiesterase 4D.

    PubMed

    Huo, Zhaoxia; Ye, Jiang-Chuan; Chen, Jinjin; Lin, Xiaoping; Zhou, Zhao-Nian; Xu, Xin-Ran; Li, Chang-Ming; Qi, Man; Liang, Dandan; Liu, Yi; Li, Jun

    2012-10-12

    Cyclic adenosine 3',5'-monophosphate (cAMP), which is synthesized by adenylyl cyclase (AC) and degraded by phosphodiesterase (PDE), plays crucial roles in the regulation of multiple cellular functions and physiological processes. Prolyl hydroxylase domain (PHD) proteins, which belong to a family of dioxygenases that function as oxygen sensors through their hydroxylation activity, have been implicated in multiple signaling pathways. Here, we aimed to determine whether PHD played a role in regulating intracellular cAMP level in cardiomyocytes. Through the overexpression/knockdown of the PHD gene and the measurement of the cAMP content, we found that PHD2, but not PHD1 or PHD3, acts as a regulator of intracellular cAMP. In neonatal rat cardiomyocytes and H9c2 cells, the overexpression of PHD2 increased the intracellular cAMP level, whereas the PHD2 knockdown reduced it. There was no alteration in the AC expression or activity in cells that overexpressed or downregulated PHD2. The overexpression of PHD2 decreased both the protein expression and the activity of phosphodiesterase 4D (PDE4D), whereas the PHD2 knockdown increased the PDE4D expression and activity. Co-immunoprecipitation experiments revealed a direct binding between PHD2 and PDE4D and liquid chromatography-tandem mass spectrometry analyses identified the specific hydroxylation sites on PDE4D. In conclusion, PHD2 may directly interact with PDE4D to function as a novel regulator of the intracellular cAMP levels in cardiomyocytes. PMID:22975349

  7. Characterization of the MKS1 gene, a new negative regulator of the Ras-cyclic AMP pathway in Saccharomyces cerevislae

    Microsoft Academic Search

    Akira Matsuura; Yasuhiro Anraku

    1993-01-01

    In order to isolate genes that function downstream of the Ras-cAMP pathway in Saccharomyces cerevisiae, a YEp13-based genomic library was screened for clones that inhibit growth of cells with diminished A-kinase activity. One such gene, MKS1, was found to encode a hydrophilic 52 kDa protein that shares weak homology with the yeast SPT2\\/SIN1 gene product. Three lines of evidence suggest

  8. (S)-?-Chlorohydrin Inhibits Protein Tyrosine Phosphorylation through Blocking Cyclic AMP - Protein Kinase A Pathway in Spermatozoa

    PubMed Central

    Zheng, Weiwei; Yang, Bei; Pi, Jingbo; He, Gengsheng; Qu, Weidong

    2012-01-01

    ?-Chlorohydrin is a common contaminant in food. Its (S)-isomer, (S)-?-chlorohydrin (SACH), is known for causing infertility in animals by inhibiting glycolysis of spermatozoa. The aim of present work was to examine the relationship between SACH and protein tyrosine phosphorylation (PTP), which plays a critical role in regulating mammalian sperm capacitation. In vitro exposure of SACH 50 µM to isolated rat epididymal sperm inhibited PTP. Sperm-specific glyceraldehyde 3-phosphate dehydrogenase (GAPDS) activities, the intracellular adenosine 5?-triphosphate (ATP) levels, 3?-5?-cyclic adenosine monophosphate (cAMP) levels and phosphorylation of protein kinase A (PKA) substrates in rat sperm were diminished dramatically, indicating that both glycolysis and the cAMP/PKA signaling pathway were impaired by SACH. The inhibition of both PTP and phosphorylation of PKA substrates by SACH could be restored by addition of cAMP analog dibutyryl-cAMP (dbcAMP) and phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Moreover, addition of glycerol protected glycolysis, ATP levels, phosphorylation of PKA substrates and PTP against the influence of SACH. These results suggested SACH inhibited PTP through blocking cAMP/PKA pathway in sperm, and PTP inhibition may play a role in infertility associated with SACH. PMID:22916194

  9. (S)-?-chlorohydrin inhibits protein tyrosine phosphorylation through blocking cyclic AMP - protein kinase A pathway in spermatozoa.

    PubMed

    Zhang, Hao; Yu, Huan; Wang, Xia; Zheng, Weiwei; Yang, Bei; Pi, Jingbo; He, Gengsheng; Qu, Weidong

    2012-01-01

    ?-Chlorohydrin is a common contaminant in food. Its (S)-isomer, (S)-?-chlorohydrin (SACH), is known for causing infertility in animals by inhibiting glycolysis of spermatozoa. The aim of present work was to examine the relationship between SACH and protein tyrosine phosphorylation (PTP), which plays a critical role in regulating mammalian sperm capacitation. In vitro exposure of SACH 50 µM to isolated rat epididymal sperm inhibited PTP. Sperm-specific glyceraldehyde 3-phosphate dehydrogenase (GAPDS) activities, the intracellular adenosine 5'-triphosphate (ATP) levels, 3'-5'-cyclic adenosine monophosphate (cAMP) levels and phosphorylation of protein kinase A (PKA) substrates in rat sperm were diminished dramatically, indicating that both glycolysis and the cAMP/PKA signaling pathway were impaired by SACH. The inhibition of both PTP and phosphorylation of PKA substrates by SACH could be restored by addition of cAMP analog dibutyryl-cAMP (dbcAMP) and phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Moreover, addition of glycerol protected glycolysis, ATP levels, phosphorylation of PKA substrates and PTP against the influence of SACH. These results suggested SACH inhibited PTP through blocking cAMP/PKA pathway in sperm, and PTP inhibition may play a role in infertility associated with SACH. PMID:22916194

  10. Inhibition of human platelet cyclic AMP phosphodiesterase and of platelet aggregation by a hemisynthetic flavonoid, amentoflavone hexaacetate.

    PubMed

    Beretz, A; Briançon-Scheid, F; Stierlé, A; Corre, G; Anton, R; Cazenave, J P

    1986-01-15

    Amentoflavone hexaacetate (AmAc) was synthesized from natural amentoflavone (Am), a biflavonoid extracted from Viburnum lantana L. Am does not inhibit aggregation of intact platelets up to a concentration of 100 microM but inhibits human platelet cAMP phosphodiesterase (IC50 = 22.0 microM). AmAc is a potent inhibitor of the aggregation of washed human platelets induced by ADP (IC50 = 2.3 microM) or collagen (IC50 = 4.7 microM). AmAc inhibits crude (IC50 = 8.6 microM) or partially purified (IC50 = 42.2 microM) human platelet cAMP phosphodiesterase. In the presence of prostaglandin E1, AmAc (10 microM) induces a 3.7-fold increase in total platelet cAMP. The characteristics of this action suggest a role for cAMP in the mechanism of action of AmAc. The incubation of AmAc with intact platelets for 5 min is necessary for its activity. PMID:3002388

  11. Dibutyryl cyclic AMP stimulation of a monocyte-like cell line, U937: a model for monocyte chemotaxis and Fc receptor-related functions.

    PubMed Central

    Sheth, B; Dransfield, I; Partridge, L J; Barker, M D; Burton, D R

    1988-01-01

    Treatment of the U937 cell line with 1 mM dibutyryl cyclic AMP (Bt2cAMP) resulted in a reduction in cell size and inhibition of DNA synthesis, and morphologically the cells appeared similar to macrophages. Electron micrographs indicated an increase in intracellular apparatus, whilst histochemical studies revealed smaller, denser nuclei and a greater intensity of non-specific esterase staining. Ia-like antigens (HLA-DR and HLA-DC) and complement receptor CR1 were not detected on U937 cells by monoclonal antibodies, nor were they induced by Bt2cAMP. CR3 was present in small amounts on U937 cells, and stimulation with Bt2cAMP increased the expression of this molecule in the cytoplasm and on the cell surface. Leu M3, a monocyte-specific antibody, was weakly reactive on both unstimulated and stimulated cells, whereas transferrin receptors, present on 90% of U937 cells, were lost after 48-hr stimulation with Bt2cAMP. JW6 and NH6, two monoclonal antibodies raised in our laboratory and found to be against immature monocytic antigens, showed decreased expression on stimulation. Monomer IgG binding via Fc receptors decreased on stimulated cells, and a monoclonal antibody (32.2) specific for FcRI confirmed this to be due to a decrease in the number of high-affinity receptors, rather than a decrease in IgG-binding affinity. In contrast, expression of the low-affinity FcRII, monitored by monoclonal antibody IV3, increased dramatically after stimulation. Other functional changes included the production of superoxide anions and the induction of non-specific phagocytosis. Two dimensional gel analysis, of detergent soluble proteins from unstimulated and 48-hr stimulated U937 cells, showed many differences in protein expression. A detailed investigation of these changes will facilitate a better understanding of the molecular mechanisms involved in the differentiation of U937 cells. Images Figure 2 Figure 3 Figure 6 PMID:2832314

  12. Characterization of prostanoid receptor-evoked responses in rat sensory neurones

    PubMed Central

    Smith, Jacqueline A M; Amagasu, Shanti M; Eglen, Richard M; Hunter, John C; Bley, Keith R

    1998-01-01

    Prostanoid receptor-mediated sensitization, or excitation, of sensory nerve fibres contributes to the generation of hyperalgesia. To characterize the prostanoid receptors present on sensory neurones, biochemical assays were performed on primary cultures of adult rat dorsal root ganglia (DRG) and the F-11 (embryonic rat DRG×neuroblastoma hybrid) cell line.In DRG cultures, the IP receptor agonists, cicaprost and carbaprostacyclin (cPGI2) stimulated cyclic AMP accumulation. Prostaglandin E2 (PGE2) also increased cyclic AMP levels, but to a lesser extent, while carbocyclic thromboxane A2 (cTxA2), PGD2 and PGF2? had negligible effects. The rank order of agonist potency was cicaprost >PGE2=BMY45778=cPGI2=PGI2. In the F-11 cells, the rank order of agonist potency for the stimulation of cyclic AMP accumulation was: cicaprost>iloprost=cPGI2=PGI2=BMY45778>PGE2=cTXA2. In DRG cultures, cicaprost induced significantly more accumulation of inositol phosphates than PGE2.To examine the effects of prostanoids on C-fibre activity, extracellular recordings of d.c. potentials from the rat isolated vagus nerve were made with the ‘grease-gap' technique. PGI2 (0.1?nM–10??M) produced the largest depolarizations of the nerve. The rank order of agonist potency was: PGI2=cPGI2=PGE1>cTXA2>PGE2=PGD2=TXB2>PGF2?.Prior depolarization of nerves with either forskolin (10??M) or phorbol dibutyrate (1??M) alone significantly reduced the response to PGI2 (10??M), while simultaneous application of both forskolin and phorbol dibutyrate attenuated PGI2 responses almost completely.Putative EP1 and/or TP receptor-selective antagonists had no effect on the responses to PGI2, cPGI2 or PGE2 in the three preparations studied.Collectively, these data are consistent with a positive coupling of IP receptors to both adenylyl cyclase and phospholipase C in sensory neurones. These findings suggest that IP receptors play a major role in the sensitization of rat sensory neurones. PMID:9647476

  13. An Exploratory Trial of Cyclooxygenase Type 2 Inhibitor in HIV-1 Infection: Downregulated Immune Activation and Improved T Cell-Dependent Vaccine Responses?

    PubMed Central

    Pettersen, Frank O.; Torheim, Eirik A.; Dahm, Anders E. A.; Aaberge, Ingeborg S.; Lind, Andreas; Holm, Malin; Aandahl, Einar M.; Sandset, Per M.; Taskén, Kjetil; Kvale, Dag

    2011-01-01

    Chronic HIV infection is characterized by chronic immune activation and dysfunctional T cells with elevated intracellular cyclic AMP (cAMP), which inhibits the T cell activation capability. cAMP may be induced by prostaglandin E2 following lipopolysaccharide (LPS)-induced upregulation of cyclooxygenase type 2 (COX-2) in monocytes due to the elevated LPS levels in patients with chronic HIV infection. This hypothesis was tested using celecoxib, a COX-2 inhibitor, for 12 weeks in HIV-infected patients without antiretroviral treatment in a prospective, open, randomized exploratory trial. Thirty-one patients were randomized in the trial; 27 completed the study, including 13 patients on celecoxib. Celecoxib reduced chronic immune activation in terms of CD38 density on CD8+ T cells (?24%; P = 0.04), IgA levels (P = 0.04), and a combined score for inflammatory markers (P < 0.05). Celecoxib further reduced the inhibitory surface receptor programmed death 1 (PD-1) on CD8+ T cells (P = 0.01), including PD-1 on the HIV Gag-specific subset (P = 0.02), enhanced the number of CD3+ CD4+ CD25+ CD127lo/? Treg or activated cells (P = 0.02), and improved humoral memory recall responses to a T cell-dependent vaccine (P = 0.04). HIV RNA (P = 0.06) and D dimers (P = 0.07) tended to increase in the controls, whereas interleukin-6 (IL-6) possibly decreased in the treatment arm (P = 0.10). In conclusion, celecoxib downmodulated the immune activation related to clinical progression of chronic HIV infection and improved T cell-dependent functions in vivo. PMID:21490090

  14. PAC1hop, null and hip receptors mediate differential signaling through cyclic AMP and calcium leading to splice variant-specific gene induction in neural cells

    PubMed Central

    Holighaus, Yvonne; Mustafa, Tomris; Eiden, Lee E.

    2011-01-01

    Pituitary adenylate cyclase-activating polypeptide (PACAP)-mediated activation of its G protein-coupled receptor PAC1 results in activation of the two G proteins Gs and Gq to alter second messenger generation and gene transcription in the nervous system, important for homeostatic responses to stress and injury. Heterologous expression of the three major splice variants of the rat PAC1 receptor, PAC1hop, null and hip, in neural NG108-15 cells conferred PACAP-mediated intracellular cAMP generation, while elevation of [Ca2+]i occurred only in PAC1hop-, and to a lesser extent in PAC1null-expressing cells. Induction of vasoactive intestinal polypeptide (VIP) and stanniocalcin 1 (STC1), two genes potentially involved in PACAP’s homeostatic responses, was examined as a function of the expressed PAC1 variant. VIP induction was greatest in PAC1hop-expressing cells, suggesting that a maximal transcriptional response requires combinatorial signaling through both cAMP and Ca2+. STC1 induction was similar for all three receptor splice variants and was mimicked by the adenylate cyclase activator forskolin, indicating that cAMP elevation is sufficient to induce STC1. The degree of activation of two different second messenger pathways appears to determine the transcriptional response, suggesting that cellular responses to stressors are fine-tuned through differential receptor isoform expression. Signaling to the VIP gene proceeded through cAMP and protein kinase A (PKA) in these cells, independently of the MAP kinase ERK1/2. STC1 gene induction by PACAP was dependent on cAMP and ERK1/2, independently of PKA. Differential gene induction via different cAMP dependent signaling pathways potentially provides further targets for the design of treatments for stress-associated disorders. PMID:21693142

  15. Long-Term Memory for Place Learning Is Facilitated by Expression of cAMP Response Element-Binding Protein in the Dorsal Hippocampus

    ERIC Educational Resources Information Center

    Brightwell, Jennifer J.; Smith, Clayton A.; Neve, Rachael L.; Colombo, Paul J.

    2007-01-01

    Extensive research has shown that the hippocampus is necessary for consolidation of long-term spatial memory in rodents. We reported previously that rats using a place strategy to solve a cross maze task showed sustained phosphorylation of hippocampus cyclic AMP response element-binding protein (CREB), a transcription factor implicated in…

  16. Neural activation during response competition

    NASA Technical Reports Server (NTRS)

    Hazeltine, E.; Poldrack, R.; Gabrieli, J. D.

    2000-01-01

    The flanker task, introduced by Eriksen and Eriksen [Eriksen, B. A., & Eriksen, C. W. (1974). Effects of noise letters upon the identification of a target letter in a nonsearch task. Perception & Psychophysics, 16, 143--149], provides a means to selectively manipulate the presence or absence of response competition while keeping other task demands constant. We measured brain activity using functional magnetic resonance imaging (fMRI) during performance of the flanker task. In accordance with previous behavioral studies, trials in which the flanking stimuli indicated a different response than the central stimulus were performed significantly more slowly than trials in which all the stimuli indicated the same response. This reaction time effect was accompanied by increases in activity in four regions: the right ventrolateral prefrontal cortex, the supplementary motor area, the left superior parietal lobe, and the left anterior parietal cortex. The increases were not due to changes in stimulus complexity or the need to overcome previously learned associations between stimuli and responses. Correspondences between this study and other experiments manipulating response interference suggest that the frontal foci may be related to response inhibition processes whereas the posterior foci may be related to the activation of representations of the inappropriate responses.

  17. Repression of Protein Kinase C and Stimulation of Cyclic AMP Response Elements by Fumonisin, a Fungal Encoded Toxin Which Is a Carcinogen1

    Microsoft Academic Search

    Chongxi Huang; Martin Dickman; Gail Henderson; Clinton Jones

    1995-01-01

    Fusarium monili\\/orme (FM) is a major fungal pathogen of corn and is involved with stalk rot disease. FM is widely spread throughout the world, including the United States. Most strains of FM produce several nij co- toxins, the most prominent of which is called fumonisin. Recent epidemi ológica! studies indicated that ingestion of fumonisin correlates with a higher incidence of

  18. Post Graduate Activities Response Rates

    E-print Network

    Lipson, Michal

    Post Graduate Activities Response Rates Most Frequently Selected Fields, with average salaries www engineers will be at the forefront of solving issues facing society in the next generations. Bachelors Laboratory LG Electronics Marconi Institute of Technology Microsoft MITRE Corporation NVIDIA QED Systems LLC

  19. Post Graduate Activities Response Rates

    E-print Network

    Lipson, Michal

    Post Graduate Activities Response Rates Most Frequently Selected Fields, with average salaries www engineers will be at the forefront of solving issues facing society in the next generations. Bachelors Microsoft MITRE Corporation NVIDIA QED Systems LLC Qualcomm, Inc. Ropes and Gray LLP Siemens AG Soft Servo

  20. Appetitive Cue-Evoked ERK Signaling in the Nucleus Accumbens Requires NMDA and D1 Dopamine Receptor Activation and Regulates CREB Phosphorylation

    ERIC Educational Resources Information Center

    Kirschmann, Erin K. Z.; Mauna, Jocelyn C.; Willis, Cory M.; Foster, Rebecca L.; Chipman, Amanda M.; Thiels, Edda

    2014-01-01

    Conditioned stimuli (CS) can modulate reward-seeking behavior. This modulatory effect can be maladaptive and has been implicated in excessive reward seeking and relapse to drug addiction. We previously demonstrated that exposure to an appetitive CS causes an increase in the activation of extracellular signal-regulated kinase (ERK) and cyclic-AMP

  1. Cyclic AMP-dependent phosphorylation modifies the gating properties of L-type Ca2+ channels in bovine adrenal chromaffin cells.

    PubMed

    Doupnik, C A; Pun, R Y

    1992-01-01

    We investigated the effects of cAMP-dependent phosphorylation on the voltage- and time-dependent gating properties of Ca2+ channel currents recorded from bovine adrenal chromaffin cells under whole-cell voltage clamp. Extracellular perfusion with the membrane-permeant activator of cAMP-dependent protein kinase, 8-bromo(8-Br)-cAMP (1 mM), caused a 49%, 29%, and 21% increase in Ca2+ current (ICa) amplitudes evoked by voltage steps to 0, +10, and +20 mV respectively (mean values from eight cells, p less than or equal to 0.05). Analysis of voltage-dependent steady-state activation (m infinity) curves revealed a 0.70 +/- 0.27 charge increase in the activation-gate valency (zm) following 8-Br-cAMP perfusion. Similar responses were observed when Ba2+ was the charge carrier, where zm was increased by 1.33 +/- 0.34 charges (n = 8). The membrane potential for half activation (V1/2) was also significantly shifted 6 mV more negative for IBa (mean, n = 8). The time course for IBa (and ICa) activation was well described by second-order m2 kinetics. The derived time constant for activation (tau m) was voltage-dependent, and the tau m/V relation shifted negatively after 8-Br-cAMP treatment. Ca2+ channel gating rates were derived from the tau m and m infinity 2 values according to a Hodgkin-Huxley type m2 activation process. The forward rate (alpha m) for channel activation was increased by 8-Br-cAMP at membrane potentials greater than or equal to 0 mV, and the backward rate (beta m) decreased at potentials less than or equal to + 10 mV. Time-dependent inactivation of ICa consisted of a slowly decaying component (tau h approximately 300 ms) and a "non-inactivating" steady-state component. The currents contributed by the two inactivation processes displayed different voltage dependences, the effects of 8-Br-cAMP being exclusively on the slowly inactivating L-type component. PMID:1313168

  2. Role of cyclic AMP sensor Epac1 in masseter muscle hypertrophy and myosin heavy chain transition induced by ?2-adrenoceptor stimulation.

    PubMed

    Ohnuki, Yoshiki; Umeki, Daisuke; Mototani, Yasumasa; Jin, Huiling; Cai, Wenqian; Shiozawa, Kouichi; Suita, Kenji; Saeki, Yasutake; Fujita, Takayuki; Ishikawa, Yoshihiro; Okumura, Satoshi

    2014-12-15

    The predominant isoform of ?-adrenoceptor (?-AR) in skeletal muscle is ?2-AR and that in the cardiac muscle is ?1-AR. We have reported that Epac1 (exchange protein directly activated by cAMP 1), a new protein kinase A-independent cAMP sensor, does not affect cardiac hypertrophy in response to pressure overload or chronic isoproterenol (isoprenaline) infusion. However, the role of Epac1 in skeletal muscle hypertrophy remains poorly understood. We thus examined the effect of disruption of Epac1, the major Epac isoform in skeletal muscle, on masseter muscle hypertrophy induced by chronic ?2-AR stimulation with clenbuterol (CB) in Epac1-null mice (Epac1KO). The masseter muscle weight/tibial length ratio was similar in wild-type (WT) and Epac1KO at baseline and was significantly increased in WT after CB infusion, but this increase was suppressed in Epac1KO. CB treatment significantly increased the proportion of myosin heavy chain (MHC) IIb at the expense of that of MHC IId/x in both WT and Epac1KO, indicating that Epac1 did not mediate the CB-induced MHC isoform transition towards the faster isoform. The mechanism of suppression of CB-mediated hypertrophy in Epac1KO is considered to involve decreased activation of Akt signalling. In addition, CB-induced histone deacetylase 4 (HDAC4) phosphorylation on serine 246 mediated by calmodulin kinase II (CaMKII), which plays a role in skeletal muscle hypertrophy, was suppressed in Epac1KO. Our findings suggest that Epac1 plays a role in ?2-AR-mediated masseter muscle hypertrophy, probably through activation of both Akt signalling and CaMKII/HDAC4 signalling. PMID:25344550

  3. HAWC Response to Lighting Activity

    NASA Astrophysics Data System (ADS)

    Lara, A.

    2014-12-01

    The High Altitude Water Cherenkov (HAWC) observatory is being constructed at the Sierra Negra volcano (4100 m a.s.l.) in Mexico. HAWC's primary purpose is the study of both: galactic and extra-galactic sources of high energy gamma rays. HAWC will consist of 300 large water Cherenkov detectors (WCD), each instrumented with 4 photo-multipliers (PMTs). The Data taking has already started while construction continues, with the completion projected for late 2014. The HAWC scaler system records the rates of individual PMTs giving the opportunity of study relatively low energy transients as solar energetic particles and the solar modulation of galactic cosmic rays. In this work, we present the observations of scaler rate enhancements associated with lightning activity observed close to HAWC (i. e. at high altitude). In particular, we present the time and space coincidence of the lighting strikes and the scaler enhancements and our preliminary speculations on the origin of the detector response to the lighting activity.

  4. Widespread receptivity to neuropeptide PDF throughout the neuronal circadian clock network of Drosophila revealed by real-time cyclic AMP imaging

    PubMed Central

    Shafer, Orie T.; Kim, Dong Jo; Dunbar-Yaffe, Richard; Nikolaev, Viacheslav O.; Lohse, Martin J.; Taghert, Paul H.

    2008-01-01

    Summary The neuropeptide PDF is released by sixteen clock neurons in Drosophila and helps maintain circadian activity rhythms by coordinating a network of ~150 neuronal clocks. Whether PDF acts directly on elements of this neural network remains unknown. We address this question by adapting Epac1-camps, a genetically encoded cAMP FRET sensor, for use in the living brain. We find that a subset of the PDF-expressing neurons respond to PDF with long-lasting cAMP increases, and confirm that such responses require the PDF receptor. In contrast, an unrelated Drosophila neuropeptide, DH 31, stimulates large cAMP increases in all PDF-expressing clock neurons. Thus the network of ~150 clock neurons displays widespread, though not uniform, PDF receptivity. This work introduces a sensitive means of measuring cAMP changes in a living brain with sub-cellular resolution. Specifically, it experimentally confirms the longstanding hypothesis that PDF is a direct modulator of most neurons in the Drosophila clock network. PMID:18439407

  5. Sustained antagonism of acute ethanol-induced ataxia following microinfusion of cyclic AMP and cpt-cAMP in the mouse cerebellum.

    PubMed

    Dar, M Saeed

    2011-05-01

    Ataxia is a conspicuous physical manifestation of alcohol consumption in humans and laboratory animals. Previously we reported possible involvement of cAMP in ethanol-induced ataxia. We now report a sustained antagonism of ataxia due to multiple ethanol injections following intracerebellar (ICB) cAMP or cpt-cAMP microinfusion. Adenylyl cyclase drugs cAMP, cpt-cAMP, Sp-cAMP, Rp-cAMP, adenosine A? agonist, N?-cyclohexyladenosine (CHA) and GABA(A) agonist muscimol were directly microinfused into the cerebellum of CD-1 male mice to evaluate their effect on ethanol (2 g/kg; i.p.) ataxia. Drug microinfusions were made via stereotaxically implanted stainless steel guide cannulas. Rotorod was used to evaluate the ethanol's ataxic response. Intracerebellar cAMP (0.1, 1, 10 fmol) or cpt-cAMP (0.5, 1, 2 fmol) 60 min before ethanol treatment, dose-dependently attenuated ethanol-induced ataxia in general agreement with previous observations. Intracerebellar microinfusion of cAMP (100 fmol) or cpt-cAMP (2 fmol) produced a sustained attenuation of ataxia following ethanol administration at 1, 4, 7 and 25 h or 31 h post-cAMP/cpt-cAMP microinfusion. At 31 h post-cAMP, the ataxic response of ethanol reappeared. Additionally, marked antagonism to the accentuation of ethanol-induced ataxia by adenosine A? and GABA(A) agonists, CHA (34 pmol) and muscimol (88 pmol), respectively, was noted 24h after cAMP and cpt-cAMP treatment. This indicated possible participation of AC/cAMP/PKA signaling in the co-modulation of ethanol-induced ataxia by A? adenosinergic and GABAergic systems. No change in normal motor coordination was noted when cAMP or cpt-cAMP microinfusion was followed by saline. Finally, Rp-cAMP (PKA inhibitor, 22 pmol) accentuated ethanol-induced ataxia and antagonized its attenuation by cAMP whereas Sp-cAMP (PKA activator, 22 pmol) produced just the opposite effects, further indicating participation of cAMP-dependent PKA downstream. Overall, the results support a role of AC/cAMP/PKA signaling in the expression of ethanol-induced ataxia and its co-modulation by adenosine A? and GABA(A) receptors. PMID:21192968

  6. Spinal Glia Division Contributes to Conditioning Lesion-Induced Axon Regeneration Into the Injured Spinal Cord: Potential Role of Cyclic AMP-Induced Tissue Inhibitor of Metalloproteinase-1.

    PubMed

    Liu, Huaqing; Angert, Mila; Nishihara, Tasuku; Shubayev, Igor; Dolkas, Jennifer; Shubayev, Veronica I

    2015-06-01

    Regeneration of sensory neurons after spinal cord injury depends on the function of dividing neuronal-glial antigen 2 (NG2)-expressing cells. We have shown that increases in the number of dividing NG2-positive cells through short-term pharmacologic inhibition of matrix metalloproteinases contributes to recovery after spinal cord injury. A conditioning sciatic nerve crush (SNC) preceding spinal cord injury stimulates central sensory axon regeneration via the intraganglionic action of cyclic adenosine monophosphate. Here, using bromodeoxyuridine, mitomycin (mitosis inhibitor), and cholera toxin B tracer, we demonstrate that SNC-induced division of spinal glia is related to the spinal induction of tissue inhibitor of metalloproteinase-1 and contributes to central sensory axon growth into the damaged spinal cord. Dividing cells were mainly NG2-positive and Iba1-positive and included myeloid NG2-positive populations. The cells dividing in response to SNC mainly matured into oligodendrocytes and microglia within the injured spinal cord. Some postmitotic cells remained NG2-reactive and were associated with regenerating fibers. Moreover, intraganglionic tissue inhibitor of metalloproteinase-1 expression was induced after administration of SNC or cyclic adenosine monophosphate analog (dbcAMP) to dorsal root ganglia in vivo and in primary adult dorsal root ganglia cultures. Collectively, these findings support a novel model whereby a cyclic adenosine monophosphate-activated regeneration program induced in sensory neurons by a conditioning peripheral nerve lesion uses tissue inhibitor of metalloproteinase-1 to protect against short-term proteolysis, enabling glial cell division and promoting axon growth into the damaged CNS. PMID:25933384

  7. Protein kinase activity associated with pancreatic zymogen granules.

    PubMed Central

    Burnham, D B; Munowitz, P; Thorn, N; Williams, J A

    1985-01-01

    Purified zymogen granules were prepared from rat pancreas by using an iso-osmotic Percoll gradient. In the presence of [gamma-32P]ATP, phosphorylation of several granule proteins was induced by Ca2+, most notably a Mr-13 000 protein, whereas addition of cyclic AMP was without effect. When phosphatidylserine was also added, Ca2+ increased the phosphorylation of additional proteins, with the largest effect on a protein of Mr 62 000. Purified granules were also able to phosphorylate exogenous substrates. Ca2+-induced phosphorylation of lysine-rich histone was enhanced over 3-fold in the presence of phosphatidylserine, and cyclic AMP-activated protein kinase activity was revealed with mixed histone as substrate. The concentrations of free Ca2+ and cyclic AMP required for half-maximal phosphorylation of both endogenous and exogenous proteins were 1-3 microM and 57 nM respectively. Treatment of granules with 0.25 M-KCl resulted in the release of phosphatidylserine-dependent kinase activity into a high-speed granule supernatant. In contrast, granule-protein substrates of Ca2+-activated kinase activity were resistant to KCl extraction, and in fact were present in purified granule membranes. Kinase activity activated by cyclic AMP was not extracted by KCl treatment. It is concluded that phosphorylation of integral membrane proteins in the zymogen granule can be induced by one or more Ca2+-activated protein kinases. Such a reaction is a potential mechanism by which exocytosis may be regulated in the exocrine pancreas by Ca2+-mediated secretagogues. Images Fig. 1. Fig. 2. Fig. 7. Fig. 8. PMID:4004796

  8. Activating transcription factor 3 and the nervous system.

    PubMed

    Hunt, David; Raivich, Gennadij; Anderson, Patrick Norval

    2012-01-01

    Activating transcription factor 3 (ATF3) belongs to the ATF/cyclic AMP responsive element binding family of transcription factors and is often described as an adaptive response gene whose activity is usually regulated by stressful stimuli. Although expressed in a number of splice variants and generally recognized as a transcriptional repressor, ATF3 has the ability to interact with a number of other transcription factors including c-Jun to form complexes which not only repress, but can also activate various genes. ATF3 expression is modulated mainly at the transcriptional level and has markedly different effects in different types of cell. The levels of ATF3 mRNA and protein are normally very low in neurons and glia but their expression is rapidly upregulated in response to injury. ATF3 expression in neurons is closely linked to their survival and the regeneration of their axons following axotomy, and that in peripheral nerves correlates with the generation of a Schwann cell phenotype that is conducive to axonal regeneration. ATF3 is also induced by Toll-like receptor (TLR) ligands but acts as a negative regulator of TLR signaling, suppressing the innate immune response which is involved in immuno-surveillance and can enhance or reduce the survival of injured neurons and promote the regeneration of their axons. PMID:22347845

  9. Allergic manifestations and cutaneous histamine responses in patients with McCune Albright syndrome

    PubMed Central

    2013-01-01

    Background McCune Albright syndrome (MAS) is a rare disorder characterized by precocious puberty, café-au-lait spots, and fibrous dysplasia. Its cause is an activating mutation in the GNAS gene, encoding a subunit of the stimulatory G protein, Gsalpha (Gs?). The action of any mediator that signals via Gs? and cyclic AMP can be up regulated in MAS. We had observed gastritis, gastroesophageal reflux, and anaphylaxis in McCune Albright patients. Objective As histamine is known to signal via histamine 1 (H1) and histamine 2 (H2) receptors, which couple with stimulatory G proteins, we attempted to mechanistically link histamine responsiveness to the activating GNAS mutation. We hypothesized that responsiveness to histamine skin testing would differ between MAS patients and healthy controls. Patients and methods After obtaining informed consent, we performed a systematic review of histamine responsiveness and allergic manifestations in 11 MAS patients and 11 sex-matched, Tanner-stage matched controls. We performed skin prick testing, quantifying the orthogonal diameters of wheals and erythema. We also quantitated G protein mRNA expression. Results The peak wheal and flare responses to histamine were significantly higher in MAS patients compared to controls. Conclusions This study suggests that MAS patients may be at risk for exaggerated histamine responsiveness compared to unaffected controls. PMID:23663565

  10. Resveratrol Inhibits LPS-Induced MAPKs Activation via Activation of the Phosphatidylinositol 3-Kinase Pathway in Murine RAW 264.7 Macrophage Cells

    PubMed Central

    Liu, Bin; Deng, Yi-Shu; Zhan, Dong; Chen, Yuan-Li; He, Ying; Liu, Jing; Zhang, Zong-Ji; Sun, Jun; Lu, Di

    2012-01-01

    Background Resveratrol is a natural polyphenolic compound that has cardioprotective, anticancer and anti-inflammatory properties. We investigated the capacity of resveratrol to protect RAW 264.7 cells from inflammatory insults and explored mechanisms underlying inhibitory effects of resveratrol on RAW 264.7 cells. Methodology/Principal Findings Murine RAW 264.7 cells were treated with resveratrol (1, 5, and 10 µM) and/or LPS (5 µg/ml). Nitric oxide (NO) and prostaglandin E2 (PGE2) were measured by Griess reagent and ELISA. The mRNA and protein levels of proinflammatory proteins and cytokines were analysed by ELISA, RT-PCR and double immunofluorescence labeling, respectively. Phosphorylation levels of Akt, cyclic AMP-responsive element-binding protein (CREB), mitogen-activated protein kinases (MAPKs) cascades, AMP-activated protein kinase (AMPK) and expression of SIRT1(Silent information regulator T1) were measured by western blot. Wortmannin (1 µM), a specific phosphatidylinositol 3-kinase (PI3-K) inhibitor, was used to determine if PI3-K/Akt signaling pathway might be involved in resveratrol’s action on RAW 264.7 cells. Resveratrol significantly attenuated the LPS-induced expression of nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-? (TNF-?) and interleukin-1? (IL-1?) in RAW 264.7 cells. Resveratrol increased Akt phosphorylation in a time-dependent manner. Wortmannin, a specific phosphatidylinositol 3-kinase (PI3-K) inhibitor, blocked the effects of resveratrol on LPS-induced RAW 264.7 cells activation. In addition, PI3-K inhibition partially abolished the inhibitory effect of resveratrol on the phosphorylation of cyclic AMP-responsive element-binding protein (CREB) and mitogen-activated protein kinases (MAPKs) cascades. Meanwhile, PI3-K is essential for resveratrol-mediated phosphorylation of AMPK and expression of SIRT1. Conclusion and Implications This investigation demonstrates that PI3-K/Akt activation is an important signaling in resveratrol-mediated activation of AMPK phosphorylation and SIRT1 expression, and inhibition of phosphorylation of CREB and MAPKs activation, proinflammatory mediators and cytokines production in response to LPS in RAW 264.7 cells. PMID:22952890

  11. CYCLIC AMP STIMULATION OF ELECTROGENIC UPTAKE OF Na+ AND Cl2 ACROSS THE GILL EPITHELIUM OF THE CHINESE CRAB ERIOCHEIR SINENSIS

    Microsoft Academic Search

    S. RIESTENPATT; W. ZEISKE; H. ONKEN

    Summary Split gill lamellae (epithelium plus cuticle) of hyperregulating Chinese crabs acclimated to fresh water were mounted in a modified Ussing chamber. Active and electrogenic absorption of sodium and chloride were measured as positive amiloride- sensitive and negative Cl 2-dependent short-circuit currents ( INa, ICl), respectively. Both currents were characterized before and after treatment of the tissue with theophylline or

  12. The MAP kinase ERK2 inhibits the cyclic AMP-specific phosphodiesterase HSPDE4D3 by phosphorylating it at Ser579.

    PubMed Central

    Hoffmann, R; Baillie, G S; MacKenzie, S J; Yarwood, S J; Houslay, M D

    1999-01-01

    The extracellular receptor stimulated kinase ERK2 (p42(MAPK))-phosphorylated human cAMP-specific phosphodiesterase PDE4D3 at Ser579 and profoundly reduced ( approximately 75%) its activity. These effects could be reversed by the action of protein phosphatase PP1. The inhibitory state of PDE4D3, engendered by ERK2 phosphorylation, was mimicked by the Ser579-->Asp mutant form of PDE4D3. In COS1 cells transfected to express PDE4D3, challenge with epidermal growth factor (EGF) caused the phosphorylation and inhibition of PDE4D3. This effect was blocked by the MEK inhibitor PD98059 and was not apparent using the Ser579-->Ala mutant form of PDE4D3. Challenge of HEK293 and F442A cells with EGF led to the PD98059-ablatable inhibition of endogenous PDE4D3 and PDE4D5 activities. EGF challenge of COS1 cells transfected to express PDE4D3 increased cAMP levels through a process ablated by PD98059. The activity of the Ser579-->Asp mutant form of PDE4D3 was increased by PKA phosphorylation. The transient form of the EGF-induced inhibition of PDE4D3 is thus suggested to be due to feedback regulation by PKA causing the ablation of the ERK2-induced inhibition of PDE4D3. We identify a novel means of cross-talk between the cAMP and ERK signalling pathways whereby cell stimuli that lead to ERK2 activation may modulate cAMP signalling. PMID:10022832

  13. Cyclic AMP inhibits translation of cyclin D3 in T lymphocytes at the level of elongation by inducing eEF2-phosphorylation.

    PubMed

    Gutzkow, Kristine B; Låhne, Hege U; Naderi, Soheil; Torgersen, Knut Martin; Skålhegg, Bjørn; Koketsu, Mamoru; Uehara, Yoshimasa; Blomhoff, Heidi Kiil

    2003-09-01

    The purpose of the present study was to understand the mechanism by which activated protein kinase A (PKA) leads to down-regulation of cyclin D3 in lymphocytes. By using Jurkat cells as a model system, we have been able to demonstrate that cyclin D3 is reduced at the level of translation by inhibition of elongation. One of the important factors involved in translational elongation is the eukaryotic elongation factor 2 (eEF2). eEF2 promotes translation in its unphosphorylated form, and we observed a rapid phosphorylation of the eEF2-protein upon forskolin treatment. When using specific inhibitors of the eEF2-kinase prior to forskolin treatment, we were able to inhibit the increased phosphorylation of eEF2. Furthermore, inhibition of eEF2-kinase prevented the forskolin-mediated down-regulation of cyclin D3. Taken together, it appears that activation of PKA in Jurkat cells reduces the expression of cyclin D3 at the level of translational elongation by increasing the phosphorylation of eEF2 and thereby inhibiting its activity. PMID:12834812

  14. The upstream operator of the Escherichia coli galactose operon is sufficient for repression of transcription initiated at the cyclic AMP-stimulated promoter.

    PubMed Central

    Kuhnke, G; Krause, A; Heibach, C; Gieske, U; Fritz, H J; Ehring, R

    1986-01-01

    Two operators are known to bind Escherichia coli galactose repressor with roughly equal affinity. A study of the control these two operators exert on the two overlapping gal promoters is reported. The experiments rest on a set of mutations specifically constructed to inactivate individual control units of the gal operon and on quantitation of gal promoter activities. Messenger RNAs initiated at one or other of the promoters in a cell-free transcription-translation system were determined by a primer extension assay with synthetic deoxyoligonucleotide primers. The main conclusions are: (i) the classical galactose operator O1, located upstream with respect to the two overlapping promoters is sufficient for negative control of the cAMP activated promoter P1; (ii) complete repression of the second promoter P2, on the other hand, needs the presence of both intact operators O1 and O2. Thus, the two overlapping gal promoters (with only 5 bp separating their respective transcriptional start sites) are both subject to negative control by the galactose repressor. This regulation, however, is exerted by two different mechanisms. Images Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. PMID:3007113

  15. Sex differences in feeding behavior in rats: the relationship with neuronal activation in the hypothalamus

    PubMed Central

    Fukushima, Atsushi; Hagiwara, Hiroko; Fujioka, Hitomi; Kimura, Fukuko; Akema, Tatsuo; Funabashi, Toshiya

    2015-01-01

    There is general agreement that the central nervous system in rodents differs between sexes due to the presence of gonadal steroid hormone during differentiation. Sex differences in feeding seem to occur among species, and responses to fasting (i.e., starvation), gonadal steroids (i.e., testosterone and estradiol), and diet (i.e., western-style diet) vary significantly between sexes. The hypothalamus is the center for controlling feeding behavior. We examined the activation of feeding-related peptides in neurons in the hypothalamus. Phosphorylation of cyclic AMP response element-binding protein (CREB) is a good marker for neural activation, as is the Fos antigen. Therefore, we predicted that sex differences in the activity of melanin-concentrating hormone (MCH) neurons would be associated with feeding behavior. We determined the response of MCH neurons to glucose in the lateral hypothalamic area (LHA) and our results suggested MCH neurons play an important role in sex differences in feeding behavior. In addition, fasting increased the number of orexin neurons harboring phosphorylated CREB in female rats (regardless of the estrous day), but not male rats. Glucose injection decreased the number of these neurons with phosphorylated CREB in fasted female rats. Finally, under normal spontaneous food intake, MCH neurons, but not orexin neurons, expressed phosphorylated CREB. These sex differences in response to fasting and glucose, as well as under normal conditions, suggest a vulnerability to metabolic challenges in females. PMID:25870535

  16. Sex differences in feeding behavior in rats: the relationship with neuronal activation in the hypothalamus.

    PubMed

    Fukushima, Atsushi; Hagiwara, Hiroko; Fujioka, Hitomi; Kimura, Fukuko; Akema, Tatsuo; Funabashi, Toshiya

    2015-01-01

    There is general agreement that the central nervous system in rodents differs between sexes due to the presence of gonadal steroid hormone during differentiation. Sex differences in feeding seem to occur among species, and responses to fasting (i.e., starvation), gonadal steroids (i.e., testosterone and estradiol), and diet (i.e., western-style diet) vary significantly between sexes. The hypothalamus is the center for controlling feeding behavior. We examined the activation of feeding-related peptides in neurons in the hypothalamus. Phosphorylation of cyclic AMP response element-binding protein (CREB) is a good marker for neural activation, as is the Fos antigen. Therefore, we predicted that sex differences in the activity of melanin-concentrating hormone (MCH) neurons would be associated with feeding behavior. We determined the response of MCH neurons to glucose in the lateral hypothalamic area (LHA) and our results suggested MCH neurons play an important role in sex differences in feeding behavior. In addition, fasting increased the number of orexin neurons harboring phosphorylated CREB in female rats (regardless of the estrous day), but not male rats. Glucose injection decreased the number of these neurons with phosphorylated CREB in fasted female rats. Finally, under normal spontaneous food intake, MCH neurons, but not orexin neurons, expressed phosphorylated CREB. These sex differences in response to fasting and glucose, as well as under normal conditions, suggest a vulnerability to metabolic challenges in females. PMID:25870535

  17. The Cyclic AMP-binding protein CbpB in Brucella melitensis and its role in cell envelope integrity, resistance to detergent and virulence.

    PubMed

    Liu, Wen-Juan; Dong, Hao; Peng, Xiao-Wei; Wu, Qing-Min

    2014-07-01

    Brucella melitensis possesses an operon with two components: the response regulator OtpR and a putative cAMP-dependent protein kinase regulatory subunit encoded by the BMEI0067 gene. In the previous study, the function of OtpR has been studied, while little is known about the function of the BMEI0067 gene. Using a bioinformatics approach, we showed that the BMEI0067 gene encodes an additional putative cAMP-binding protein, which we refer to as CbpB. Structural modeling predicted that CbpB has a cAMP-binding protein (CAP) domain and is structurally similar to eukaryotic protein kinase A regulatory subunits. Here, we report the characterization of CbpB, a cAMP-binding protein in Brucella melitensis, showed to be involved in mouse persistent infections. ?cbpB::km possessed cell elongation, bubble-like protrusions on cell surface and its resistance to environmental stresses (temperature, osmotic stress and detergent). Interestingly, comparative real-time qPCR assays, the cbpB mutation resulted in significantly different expression of aqpX and several penicillin-binding proteins and cell division proteins in Brucella. Combined, these results demonstrated characterization of CbpB in B. melitensis and its key role for intracellular multiplication. PMID:24850100

  18. One-day Treatment of Small Molecule 8-Bromo-cyclic AMP Analogue Induces Cell-based VEGF production for In Vitro Angiogenesis and Osteoblastic Differentiation

    PubMed Central

    Lo, Kevin W.-H.; Kan, Ho Man; Gagnon, Keith A.; Laurencin, Cato T.

    2014-01-01

    Small molecule based regenerative engineering is emerging as a promising strategy for regenerating bone tissue. Small molecule cAMP analogues have been proposed as novel biofactors for bone repair and regeneration, and while promising, the effect that these small molecules have on angiogenesis, a critical requirement for successful bone regeneration, is still unclear. Our previous research demonstrated that the small molecule cAMP analogue 8-bromoadenosine-3’,5’-cyclic monophosphate (8-Br-cAMP) was able to promote initial osteoblast adhesion on a polymeric scaffold via cAMP signaling cascades. Here, we report that 8-Br-cAMP is capable of inducing in vitro cell-based VEGF production for angiogenesis promotion. We first demonstrated that treating osteoblast-like MC3T3-E1 cells with 8-Br-cAMP for one day significantly increased VEGF production and secretion. We then demonstrated that 8-Br-cAMP induced cell-secreted VEGF is biologically active and may promote angiogenesis as evidenced by increased endothelial cells (HUVECs) migration and tubule formation. In addition, treatment of MC3T3-E1 cells with 8-Br-cAMP for as short as a single day resulted in enhanced ALP activity as well as matrix mineralization, demonstrating in vitro osteoblastic differentiation. A short term 8-Br-cAMP treatment also addresses the concern of non-specific cytotoxicity, as our data indicate that a one-day 8-Br-cAMP treatment scheme supports cellular proliferation of MC3T3-E1 cells as well as HUVECs. While the major concern associated with small molecule drugs is the risk of non-specific cytotoxicity, the short exposure treatment outlined in this paper provides a very promising strategy to mitigate the risk associated with small molecules. PMID:24493289

  19. Smooth muscle cell expression of type I cyclic GMP-dependent protein kinase is suppressed by continuous exposure to nitrovasodilators, theophylline, cyclic GMP, and cyclic AMP.

    PubMed Central

    Soff, G A; Cornwell, T L; Cundiff, D L; Gately, S; Lincoln, T M

    1997-01-01

    A key component of the nitric oxide-cyclic guanosine monophosphate (cGMP) pathway in smooth muscle cells (SMC) is the type I GMP-dependent protein kinase (PK-G I). Activation of PK-G I mediates the reduction of cytoplasmic calcium concentrations and vasorelaxation. In this manuscript, we demonstrate that continuous exposure of SMC in culture to the nitrovasodilators S-nitroso-N-acetylpenicillamine (SNAP) or sodium nitroprusside (SNP) results in approximately 75% suppression of PK-G I mRNA by 48 h. PK-G I mRNA and protein were also suppressed by continuous exposure to cGMP analogues 8-bromo- and 8-(4-chlorophenylthio) guanosine-3,5-monophosphate or the cAMP analogue dibutyryl cAMP. These results suggest that activation of one or both of the cyclic nucleotide-dependent protein kinases mediates PK-G I mRNA suppression. Using isoform-specific cDNA probes, only the PK-G I alpha was detected in SMC, either at baseline or after suppression, while PK-G I beta was not detected, indicating that isoform switch was not contributing to the gene regulation. Using the transcription inhibitor actinomycin D, the PK-G I mRNA half-life in bovine SMC was observed to be 5 h. The half-life was not affected by the addition of SNAP to actinomycin D, indicating no effect on PK-G I mRNA stability. Nuclear runoff studies indicated a suppression of PK-G I gene transcription by SNAP. PK-G I suppression was also observed in vivo in rats given isosorbide dinitrate in the drinking water, with a dose-dependent suppression of PK-G I protein in the aorta. PK-G I antigen in whole rat lung extract was also suppressed by administration of isosorbide or theophylline in the drinking water. These data may contribute to our understanding of nitrovasodilator resistance, a phenomenon resulting from continuous exposure to nitroglycerin or other nitrovasodilators. PMID:9366573

  20. Anaerobic growth of Rhodopseudomonas palustris on 4-hydroxybenzoate is dependent on AadR, a member of the cyclic AMP receptor protein family of transcriptional regulators.

    PubMed Central

    Dispensa, M; Thomas, C T; Kim, M K; Perrotta, J A; Gibson, J; Harwood, C S

    1992-01-01

    The purple nonsulfur phototrophic bacterium Rhodopseudomonas palustris converts structurally diverse aromatic carboxylic acids, including lignin monomers, to benzoate and 4-hydroxybenzoate under anaerobic conditions. These compounds are then further degraded via aromatic ring-fission pathways. A gene termed aadR, for anaerobic aromatic degradation regulator, was identified by complementation of mutants unable to grow anaerobically on 4-hydroxybenzoate. The deduced amino acid sequence of the aadR product is similar to a family of transcriptional regulators which includes Escherichia coli Fnr and Crp, Pseudomonas aeruginosa Anr, and rhizobial FixK and FixK-like proteins. A mutant with a deletion in aadR failed to grow on 4-hydroxybenzoate under anaerobic conditions and grew very slowly on benzoate. It also did not express aromatic acid-coenzyme A ligase II, an enzyme that catalyzes the first step of 4-hydroxybenzoate degradation, and it was defective in 4-hydroxybenzoate-induced expression of benzoate-coenzyme A ligase. The aadR deletion mutant was unaffected in other aspects of anaerobic growth. It grew normally on nonaromatic carbon sources and also under nitrogen-fixing conditions. In addition, aerobic growth on 4-hydroxybenzoate was indistinguishable from that of the wild type. These results indicate that AadR functions as a transcriptional activator of anaerobic aromatic acid degradation. Images PMID:1522059

  1. Cyclic AMP-dependent protein kinase phosphorylates residues in the C-terminal domain of the cardiac L-type calcium channel alpha1 subunit.

    PubMed

    Leach, R N; Brickley, K; Norman, R I

    1996-06-11

    The molecular basis of the regulation of cardiac L-type calcium channel activity by cAMP-dependent protein kinase (cA-PK) remains unclear. Direct cA-PK-dependent phosphorylation of the bovine ventricular alpha1 subunit in vitro has been demonstrated in microsomal membranes, detergent extracts and partially purified (+)-[3H]PN 200-110 receptor preparations. Two 32P-labeled phosphopeptides, derived from cyanogen bromide cleavage, of 4.7 and 9.5 kDa were immunoprecipitated specifically by site-directed antibodies against the rabbit cardiac alpha1 subunit amino acid sequences 1602-1616 and 1681-1694, respectively, consistent with phosphorylation at the cA-PK consensus sites at Ser(1627) and Ser(1700). No phosphopeptide products consistent with phosphorylation at three other C-terminal cA-PK consensus phosphorylation sites (Ser(1575), Ser(1848) and Ser(1928)) were identified using similar procedures suggesting that these sites are poor substrates for this kinase. Ser(1627) and Ser(1700) may represent sites of cA-PK phosphorylation involved in the physiological regulation of cardiac L-type calcium channel function. PMID:8664319

  2. Adenylate cyclase from synchronized neuroblastoma cells: responsiveness to prostaglandin E1, adenosine, and dopamine during the cell cycle.

    PubMed

    Pénit, J; Cantau, B; Huot, J; Jard, S

    1977-04-01

    Neuroblastoma cells were synchronized by a combined isoleucine plus glutamine starvation. Adenylate cyclase activity [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] was measured under basal conditions and in the presence of dopamine, adenosine and prostaglandin (PG) E1. A clear dissociation occurred between the respective evolution patterns of basal and agonist-stimulated adenylate cyclase activities. The magnitudes of the enzyme response to PGE1, adenosine, and dopamine also exhibited different evolution patterns during the cell cycle. Evolution of adenylate cyclase responsiveness to PGE1 during the cell cycle exhibited striking similarities with the intracellular 3':5'-cyclic AMP changes observed elsewhere. Use of theophylline and fluphenazine as specific inhibitors of adenosine and dopamine, respectively, made it possible to demonstrate that adenosine, dopamine, and PGE1 stimulated adenylate cyclase through independent receptor sites. Furthermore, whatever the stage of the cell cycle, responses to these three agonists were not additive, indicating that the receptors of adenosine, dopamine, and PGE1 control the same adenylate cyclase moieties. The data suggest that adenylate cyclase cell content and enzyme responsiveness to specific agonists can be independently controlled. PMID:266197

  3. Cyclic AMP-independent, dual regulation of voltage-dependent Ca2+ currents by LHRH and somatostatin in a pituitary cell line.

    PubMed Central

    Rosenthal, W; Hescheler, J; Hinsch, K D; Spicher, K; Trautwein, W; Schultz, G

    1988-01-01

    Voltage-dependent Ca2+ currents appear to be involved in the actions of hormones that regulate pituitary secretion. In order to investigate modulation of Ca2+ currents by release-inducing and release-inhibiting hormones, we performed whole-cell clamp experiments in the pituitary cell line GH3. The resting potential was approximately -40 mV; spontaneous action potentials were observed in the majority of cells. Superfusion of cells with the stimulatory hormone, LHRH, depolarized the plasma membrane to approximately -10 mV, whereas the inhibitory hormone, somatostatin, caused hyperpolarization to approximately -60 mV; both hormones suppressed spontaneous action potentials. Under voltage clamp conditions, GH3 cells exhibited slowly and fast inactivating Ca2+ currents. LHRH increased whereas somatostatin decreased the slowly inactivating currents; fast inactivating currents were not affected by these hormones. The stimulatory effect of LHRH was not mimicked by intracellularly applied cAMP. In contrast to vasoactive intestinal peptide and forskolin, LHRH did not activate adenylate cyclase in membranes of GH3 cells, but rather appeared to cause inhibition of the enzyme. Hormonal stimulation and inhibition of inward currents were abolished by pretreatment of the cells with pertussis toxin. In membranes of GH3 cells, we identified a pertussis toxin-sensitive G-protein of the Gi-type and Go. We conclude that LHRH and somatostatin modulate voltage-dependent Ca2+ currents via cAMP-independent mechanisms involving pertussis toxin-sensitive G-proteins. The occurrence of both pertussis toxin-sensitive hormonal stimulation and inhibition of voltage-dependent Ca2+ currents in one cell type suggest that these opposite regulations are mediated by distinct G-proteins. Images PMID:2458919

  4. Comparison of cellular responses induced by low level light in different cell types

    NASA Astrophysics Data System (ADS)

    Huang, Ying-Ying; Chen, Aaron C.-H.; Sharma, Sulbha K.; Wu, Qiuhe; Hamblin, Michael R.

    2010-02-01

    Discoveries are rapidly being made in multiple laboratories that shed "light" on the fundamental molecular and cellular mechanisms underlying the use of low level light therapy (LLLT) in vitro, in animal models and in clinical practice. Increases in cellular levels of respiration, in cytochrome c oxidase activity, in ATP levels and in cyclic AMP have been found. Increased expression of reactive oxygen species and release of nitric oxide have also been shown. In order for these molecular changes to have a major effect on cell behavior, it is likely that various transcription factors will be activated, possibly via different signal transduction pathways. In this report we compare and contrast the effects of LLLT in vitro on murine embryonic fibroblasts, primary cortical neurons, cardiomyocytes and bone-marrow derived dendritic cells. We also examined two human cell lines, HeLa cancer cells and HaCaT keratinocytes. The effects of 810-nm near-infra-red light delivered at low and high fluences were addressed. Reactive oxygen species generation, transcription factor activation and ATP increases are reported. The data has led to the hypothesis that cells with a high level of mitochondrial activity (mitochondrial membrane potential) have a higher response to light than cells with low mitochondrial activity.

  5. Constitutive and interleukin-1 (IL-1)-inducible factors interact with the IL-1-responsive element in the IL-6 gene

    SciTech Connect

    Isshiki, H.; Akira, S.; Tanabe, O.; Nakajima, T.; Shimamoto, T.; Hirano, T.; Kishimoto, T. (Div. of Cellular Immunology, Institute for Molecular and Cellular Biology, Osaka Univ., 1-3 Yamada-oka, Suita-city, Osaka 565 (JP))

    1990-06-01

    The interleukin-6 (IL-6) promoter is rapidly and transiently activated with other cytokines, including IL-1, tumor necrosis factor, and platelet-derived growth factor, as well as phorbol esters and agents that increase intracellular cyclic AMP. In this study, the authors have investigated {ital cis}-acting regulatory elements and {ital trans}-acting factors responsible for IL-1-induced IL-6 gene expression. Studies on the 5{prime} deletion mutants of the human IL-6 gene suggested that the IL-1-responsive element was mapped within the IL-6 promoter region ({minus} 180 to {minus} 123) which was homologous to the c-{ital fos} serum-responsive enhancer element. Gel retardation assay identified two types of nuclear factors that bound to this region, one constitutive and the other inducible. These two factors recognized a 14-base-pair (bp) palindromic sequence, ACATTGCACAATCT. Furthermore, three copies of this 14-bp palindrome conferred IL-1 responsiveness to the basal enhancerless IL-6 promoter, indicating that a 14-bp-dyad symmetry sequence was an IL-1-responsive element in the IL-6 gene.

  6. Electrophysiological responses of neurons in the rat spinal cord to nitric oxide.

    PubMed

    Pehl, U; Schmid, H A

    1997-03-01

    The effects of nitric oxide-containing solution and different nitric oxide donors were investigated on spontaneously active neurons using extracellular recording technique in areas of rat spinal cord slices where high levels of nitric oxide synthase are present. In lamina X, 93% of all neurons investigated (n = 84) increased their firing rate and 2% decreased it by superfusion with the nitric oxide donor sodium nitroprusside. In contrast, 49% of all neurons in laminae I and II (n = 90) were inhibited and only 28% were activated. Both effects were due to the postsynaptic action of sodium nitroprusside, because they could still be observed in medium containing 0.3 mM Ca2+ and 9 mM Mg2+, known to block synaptic transmission. Application of 8-bromo-cyclic-GMP caused an excitation of every neuron which was excited by sodium nitroprusside and an inhibition of every cell which was inhibited by sodium nitroprusside (n = 25). This effect was different from the effect of 8-bromo-cyclic-AMP, which mimicked only the excitatory, but not the inhibitory response of sodium nitroprusside. These results provide evidence that nitric oxide in the spinal cord can directly cause an excitation or an inhibition of the electrical activity of spinal neurons. Another, more general conclusion from our results is that the nitric oxide-induced production of cyclic-GMP alone does not allow any prediction about an excitatory or inhibitory effect on the neuronal activity, which has to be determined separately. PMID:9472412

  7. A0005 Cyclic AMP Receptors of Dictyostelium

    E-print Network

    Devreotes, Peter

    for the identification of the cAMP receptors. S0010Identification and Properties of cAMP Receptors P0020The molecular that yields a fruiting body comprised of a round mass of spores held aloft by a slender stalk (Figure 1A identification of the first cAMP receptor (cAR1) began with its photoaffinity labeling with the cAMP analogue, 8

  8. Spatial learning associated with stimulus response in goldfish Carassius auratus: relationship to activation of CREB signalling.

    PubMed

    Rajan, Koilmani Emmanuvel; Thangaleela, Subramanian; Balasundaram, Chellam

    2015-06-01

    Earlier, we reported spatial learning ability in goldfish (Carassius auratus) by using spatial paradigm with food reward. Therefore, we hypothesized that goldfish may use associated cue to integrate "where" and "what" for spatial memory. To test our hypothesis, we first trained goldfish to learn to cross the gate1, which is associated with spatial task. Subsequently, they were trained to learn to enter the task chamber and to identify the food reward chamber associated with visual cue (red/green light). Red and green lights were positioned randomly for each trial but always the food reward was kept in green chamber. In addition, to elucidate the role of the signalling cascade in spatial memory associated with visual cue, nicotinamide (NAM, 1000 mg/kg, i.p), a NAD(+) precursor, was used to inhibit the Sirtuin 1 (SIRT1) cyclic AMP response element binding protein (CREB) pathway. Fishes were trained for 5 days in a maze after treating with either vehicle (VEH, DD H2O) or NAM, and then, they were individually tested for memory. We found that VEH-treated fish learned and recalled the task successfully by showing less latency and making more correct choices than NAM-treated group. Subsequent analysis showed that NAM treatment significantly down-regulated the phosphorylation of extracellular signal-regulated kinase (ERK1/2), CREB, expression of SirT1 and brain-derived neurotrophic factor (Bdnf) in telencephalon. Taken together, our results provide behavioural evidence of spatial memory associated with visual cue in C. auratus, which could be regulated by ERK1/2-CREB-SirT1-Bdnf pathway. PMID:25739351

  9. Physiological Response to Physical Activity in Children.

    ERIC Educational Resources Information Center

    Gilliam, Thomas B.

    This is a report on research in the field of physical responses of children to strenuous activity. The paper is divided into three subtopics: (1) peak performance measure in children; (2) training effects on children; and (3) importance of physical activity for children. Measurements used are oxygen consumption, ventilation, heart rate, cardiac…

  10. Hepatitis B Virus HBx Protein Activation of Cyclin A-Cyclin-Dependent Kinase 2 Complexes and G1 Transit via a Src Kinase Pathway

    Microsoft Academic Search

    MICHAEL BOUCHARD; STAVROS GIANNAKOPOULOS; EDITH H. WANG; NAOKO TANESE; ROBERT J. SCHNEIDER

    2001-01-01

    Numerous studies have demonstrated that the hepatitis B virus HBx protein stimulates signal transduction pathways and may bind to certain transcription factors, particularly the cyclic AMP response element binding protein, CREB. HBx has also been shown to promote early cell cycle progression, possibly by functionally replacing the TATA-binding protein-associated factor 250 (TAFII250), a transcriptional coactivator, and\\/or by stimulating cytoplasmic signal

  11. 1-Bromopropane up-regulates cyclooxygenase-2 expression via NF-?B and C/EBP activation in murine macrophages.

    PubMed

    Han, Eun Hee; Yang, Ji Hye; Kim, Hyung-Kyun; Choi, Jae Ho; Khanal, Tilak; Do, Minh Truong; Chung, Young Chul; Lee, Kwang Youl; Jeong, Tae Cheon; Jeong, Hye Gwang

    2012-05-01

    1-Bromopropane (1-BP) has been used in industry as an alternative to ozone-depleting solvents. In the present study, we examined the effect of 1-BP on cyclooxygenase-2 (COX-2) gene expression and analyzed the molecular mechanism of its activity in murine RAW 264.7 macrophages. 1-BP dose-dependently increased COX-2 protein and mRNA levels, as well as COX-2 promoter-driven luciferase activity in macrophages. Additionally, exposure to 1-BP markedly enhanced the production of prostaglandin E(2) (PGE(2)), a major COX-2 metabolite, in macrophages. Transfection experiments with several human COX-2 promoter constructs revealed that 1-BP activated the transcription factors nuclear factor-?B (NF-?B) and CCAAT/enhancer-binding protein (C/EBP), but not AP-1 or the cyclic AMP response element binding protein. Furthermore, Akt and mitogen-activated protein (MAP) kinases were significantly activated by 1-BP. These results demonstrated that 1-BP induced COX-2 expression via NF-?B and C/EBP activation through the Akt/ERK and p38 MAP kinase pathways. These findings provide further insight into the signal transduction pathways involved in the inflammatory effects of 1-BP. PMID:22353212

  12. Active thermal isolation for temperature responsive sensors

    NASA Technical Reports Server (NTRS)

    Martinson, Scott D. (inventor); Gray, David L. (inventor); Carraway, Debra L. (inventor); Reda, Daniel C. (inventor)

    1994-01-01

    A temperature responsive sensor is located in the airflow over the specified surface of a body and is maintained at a constant temperature. An active thermal isolator is located between this temperature responsive sensor and the specified surface of the body. The temperature of this isolator is controlled to reduce conductive heat flow from the temperature responsive sensor to the body. This temperature control includes: (1) operating the isolator at the same temperature as the constant temperature of the sensor and (2) establishing a fixed boundary temperature which is either less than or equal to or slightly greater than the sensor constant temperature.

  13. PakD, a Putative p21-Activated Protein Kinase in Dictyostelium discoideum, Regulates Actin

    PubMed Central

    Garcia, Miguel; Ray, Sibnath; Brown, Isaiah; Irom, Jon

    2014-01-01

    Proper regulation of the actin cytoskeleton is essential for cell function and ultimately for survival. Tight control of actin dynamics is required for many cellular processes, including differentiation, proliferation, adhesion, chemotaxis, endocytosis, exocytosis, and multicellular development. Here we describe a putative p21-activated protein kinase, PakD, that regulates the actin cytoskeleton in Dictyostelium discoideum. We found that cells lacking pakD are unable to aggregate and thus unable to develop. Compared to the wild type, cells lacking PakD have decreased membrane extensions, suggesting defective regulation of the actin cytoskeleton. pakD? cells show poor chemotaxis toward cyclic AMP (cAMP) but normal chemotaxis toward folate, suggesting that PakD mediates some but not all chemotaxis responses. pakD? cells have decreased polarity when placed in a cAMP gradient, indicating that the chemotactic defects of the pakD? cells may be due to an impaired cytoskeletal response to cAMP. In addition, while wild-type cells polymerize actin in response to global stimulation by cAMP, pakD? cells exhibit F-actin depolymerization under the same conditions. Taken together, the results suggest that PakD is part of a pathway coordinating F-actin organization during development. PMID:24243792

  14. A novel family of dehydrin-like proteins is involved in stress response in the human fungal pathogen Aspergillus fumigatus

    PubMed Central

    Hoi, Joanne Wong Sak; Lamarre, Claude; Beau, Rémi; Meneau, Isabelle; Berepiki, Adokiye; Barre, Annick; Mellado, Emilia; Read, Nick D.; Latgé, Jean-Paul

    2011-01-01

    ?During a search for genes controlling conidial dormancy in Aspergillus fumigatus, two dehydrin-like genes, DprA and DprB, were identified. The deduced proteins had repeated stretches of 23 amino acids that contained a conserved dehydrin-like protein (DPR) motif. Disrupted DprA? mutants were hypersensitive to oxidative stress and to phagocytic killing, whereas DprB? mutants were impaired in osmotic and pH stress responses. However, no effect was observed on their pathogenicity in our experimental models of invasive aspergillosis. Molecular dissection of the signaling pathways acting upstream showed that expression of DprA was dependent on the stress-activated kinase SakA and the cyclic AMP-protein kinase A (cAMP-PKA) pathways, which activate the bZIP transcription factor AtfA, while expression of DprB was dependent on the SakA mitogen-activated protein kinase (MAPK) pathway, and the zinc finger transcription factor PacC. Fluorescent protein fusions showed that both proteins were associated with peroxisomes and the cytosol. Accordingly, DprA and DprB were important for peroxisome function. Our findings reveal a novel family of stress-protective proteins in A. fumigatus and, potentially, in filamentous ascomycetes. PMID:21490150

  15. 1. Emergency Management Plan ACTIVE SHOOTER RESPONSE

    E-print Network

    cell phone when semester starts ­ Inside.mines.edu ­ Updating our system ­ Update information1. Emergency Management Plan ACTIVE SHOOTER RESPONSE #12;The world has changed!The world has changed!The world has changed!The world has changed! Student Life and Public Safety are fully aware

  16. Active flutter and gust response control

    NASA Technical Reports Server (NTRS)

    Oli, Muluneh

    1990-01-01

    After a short recall concerning the aeroelastic equations, active control law based on optimal stochastic control theory is synthesized for a wing flutter and gust response. Robustness of the control system due to structured and unstructured uncertainties is considered. Robustness recovery technique is applied to improve the stability margin.

  17. Sensitivity of HCN channel deactivation to cAMP is amplified by an S4 mutation combined with activation mode shift

    Microsoft Academic Search

    Nadine L. Wicks; Kerry S. C. Chan; Zarina Madden; Bina Santoro; Edgar C. Young

    2009-01-01

    Hyperpolarisation–activation of HCN ion channels relies on the movement of a charged S4 transmembrane helix, preferentially\\u000a stabilising the open conformation of the ion pore gate. The open state is additionally stabilised, (a) when cyclic AMP (cAMP)\\u000a is bound to a cytoplasmic C-terminal domain or (b) when the “mode I” open state formed initially by gate opening undergoes\\u000a a “mode shift”

  18. 14 -3-3 Inhibits the Dictyostelium Myosin II Heavy Chain-specific Protein Kinase C Activity by a Direct Interaction: Identification of the 14 -3-3 Binding Domain

    Microsoft Academic Search

    Meirav Matto-Yelin; Alastair Aitken; Shoshana Ravid

    Myosin II heavy chain (MHC) specific protein kinase C (MHC-PKC), isolated from Dictyostelium discoideum, regulates myosin II assembly and localization in response to the chemoattractant cyclic AMP. Immunoprecipitation of MHC-PKC revealed that it resides as a complex with several proteins. We show herein that one of these proteins is a homologue of the 14 -3-3 protein (Dd14 -3-3). This protein

  19. Hypoxia-activated metabolic pathway stimulates phosphorylation of p300 and CBP in oxygen-sensitive cells

    PubMed Central

    Zakrzewska, Adriana; Schnell, Phillip O.; Striet, Justin B.; Hui, Anna; Robbins, Jennifer R.; Petrovic, Milan; Conforti, Laura; Gozal, David; Wathelet, Marc G.; Czyzyk-Krzeska, Maria F.

    2006-01-01

    Transcription co-activators and histone acetyltransferases, p300 and cyclic AMP responsive element-binding protein-binding protein (CBP), participate in hypoxic activation of hypoxia-inducible genes. Here, we show that exposure of PC12 and cells to 1–10% oxygen results in hyperphosphorylation of p300/CBP. This response is fast, long lasting and specific for hypoxia, but not for hypoxia-mimicking agents such as desferioxamine or Co2+ ions. It is also cell-type specific and occurs in pheochromocytoma PC12 cells and the carotid body of rats but not in hepatoblastoma cells. The p300 hyperphosphorylation specifically depends on the release of intracellular calcium from inositol 1,4,5-triphosphate (IP3)-sensitive stores. However, it is not inhibited by pharmacological inhibitors of any of the kinases traditionally known to be directly or indirectly calcium regulated. On the other hand, p300 hyperphosphorylation is inhibited by several different inhibitors of the glucose metabolic pathway from generation of NADH by glyceraldehyde 3-phosphate dehydrogenase, through the transfer of NADH through the glycerol phosphate shuttle to ubiquinone and complex III of the mitochondrial respiratory chain. Inhibition of IP3-sensitive calcium stores decreases generation of ATP, and this inhibition is significantly stronger in hypoxia than in normoxia. We propose that the NADH glycerol phosphate shuttle participates in generating a pool of ATP that serves either as a co-factor or a modulator of the kinases involved in the phosphorylation of p300/CBP during hypoxia. PMID:16000154

  20. Combinatorial regulation of a signal-dependent activator by phosphorylation and acetylation

    PubMed Central

    Paz, Jose C.; Park, Sangho; Phillips, Naomi; Matsumura, Shigenobu; Tsai, Wen-Wei; Kasper, Lawryn; Brindle, Paul K.; Zhang, Guangtao; Zhou, Ming-Ming; Wright, Peter E.; Montminy, Marc

    2014-01-01

    In the fasted state, increases in catecholamine signaling promote adipocyte function via the protein kinase A-mediated phosphorylation of cyclic AMP response element binding protein (CREB). CREB activity is further up-regulated in obesity, despite reductions in catecholamine signaling, where it contributes to the development of insulin resistance. Here we show that obesity promotes the CREB binding protein (CBP)-mediated acetylation of CREB at Lys136 in adipose. Under lean conditions, CREB acetylation was low due to an association with the energy-sensing NAD+-dependent deacetylase SirT1; amounts of acetylated CREB were increased in obesity, when SirT1 undergoes proteolytic degradation. Whereas CREB phosphorylation stimulated an association with the KIX domain of CBP, Lys136 acetylation triggered an interaction with the CBP bromodomain (BRD) that augmented recruitment of this coactivator to the promoter. Indeed, coincident Ser133 phosphorylation and Lys136 acetylation of CREB stimulated the formation of a ternary complex with the KIX and BRD domains of CBP by NMR analysis. As disruption of the CREB:BRD complex with a CBP-specific BRD inhibitor blocked effects of CREB acetylation on target gene expression, our results demonstrate how changes in nutrient status modulate cellular gene expression in response to hormonal signals. PMID:25404345

  1. Combinatorial regulation of a signal-dependent activator by phosphorylation and acetylation.

    PubMed

    Paz, Jose C; Park, Sangho; Phillips, Naomi; Matsumura, Shigenobu; Tsai, Wen-Wei; Kasper, Lawryn; Brindle, Paul K; Zhang, Guangtao; Zhou, Ming-Ming; Wright, Peter E; Montminy, Marc

    2014-12-01

    In the fasted state, increases in catecholamine signaling promote adipocyte function via the protein kinase A-mediated phosphorylation of cyclic AMP response element binding protein (CREB). CREB activity is further up-regulated in obesity, despite reductions in catecholamine signaling, where it contributes to the development of insulin resistance. Here we show that obesity promotes the CREB binding protein (CBP)-mediated acetylation of CREB at Lys136 in adipose. Under lean conditions, CREB acetylation was low due to an association with the energy-sensing NAD(+)-dependent deacetylase SirT1; amounts of acetylated CREB were increased in obesity, when SirT1 undergoes proteolytic degradation. Whereas CREB phosphorylation stimulated an association with the KIX domain of CBP, Lys136 acetylation triggered an interaction with the CBP bromodomain (BRD) that augmented recruitment of this coactivator to the promoter. Indeed, coincident Ser133 phosphorylation and Lys136 acetylation of CREB stimulated the formation of a ternary complex with the KIX and BRD domains of CBP by NMR analysis. As disruption of the CREB:BRD complex with a CBP-specific BRD inhibitor blocked effects of CREB acetylation on target gene expression, our results demonstrate how changes in nutrient status modulate cellular gene expression in response to hormonal signals. PMID:25404345

  2. Activation state of the hyperpolarization-activated current modulates temperature-sensitivity of firing in locus coeruleus neurons from bullfrogs.

    PubMed

    Santin, Joseph M; Hartzler, Lynn K

    2015-06-15

    Locus coeruleus neurons of anuran amphibians contribute to breathing control and have spontaneous firing frequencies that, paradoxically, increase with cooling. We previously showed that cooling inhibits a depolarizing membrane current, the hyperpolarization-activated current (I h) in locus coeruleus neurons from bullfrogs, Lithobates catesbeianus (Santin JM, Watters KC, Putnam RW, Hartzler LK. Am J Physiol Regul Integr Comp Physiol 305: R1451-R1464, 2013). This suggests an unlikely role for I h in generating cold activation, but led us to hypothesize that inhibition of I h by cooling functions as a physiological brake to limit the cold-activated response. Using whole cell electrophysiology in brain slices, we employed 2 mM Cs(+) (an I h antagonist) to isolate the role of I h in spontaneous firing and cold activation in neurons recorded with either control or I h agonist (cyclic AMP)-containing artificial intracellular fluid. I h did not contribute to the membrane potential (V m) and spontaneous firing at 20°C. Although voltage-clamp analysis confirmed that cooling inhibits I h, its lack of involvement in setting baseline firing and V m precluded its ability to regulate cold activation as hypothesized. In contrast, neurons dialyzed with cAMP exhibited greater baseline firing frequencies at 20°C due to I h activation. Our hypothesis was supported when the starting level of I h was enhanced by elevating cAMP because cold activation was converted to more ordinary cold inhibition. These findings indicate that situations leading to enhancement of I h facilitate firing at 20°C, yet the hyperpolarization associated with inhibiting a depolarizing cation current by cooling blunts the net V m response to cooling to oppose normal cold-depolarizing factors. This suggests that the influence of I h activation state on neuronal firing varies in the poikilothermic neuronal environment. PMID:25833936

  3. By activating matrix metalloproteinase-7, shear stress promotes chondrosarcoma cell motility, invasion and lung colonization

    PubMed Central

    Guan, Pei-Pei; Yu, Xin; Guo, Jian-Jun; Wang, Yue; Wang, Tao; Li, Jia-Yi; Konstantopoulos, Konstantinos; Wang, Zhan-You; Wang, Pu

    2015-01-01

    Interstitial fluid flow and associated shear stress are relevant mechanical signals in cartilage and bone (patho)physiology. However, their effects on chondrosarcoma cell motility, invasion and metastasis have yet to be delineated. Using human SW1353, HS.819.T and CH2879 chondrosarcoma cell lines as model systems, we found that fluid shear stress induces the accumulation of cyclic AMP (cAMP) and interleukin-1? (IL-1?), which in turn markedly enhance chondrosarcoma cell motility and invasion via the induction of matrix metalloproteinase-7 (MMP-7). Specifically, shear-induced cAMP and IL-1? activate PI3-K, ERK1/2 and p38 signaling pathways, which lead to the synthesis of MMP-7 via transactivating NF-?B and c-Jun in human chondrosarcoma cells. Importantly, MMP-7 upregulation in response to shear stress exposure has the ability to promote lung colonization of chondrosarcomas in vivo. These findings offer a better understanding of the mechanisms underlying MMP-7 activation in shear-stimulated chondrosarcoma cells, and provide insights on designing new therapeutic strategies to interfere with chondrosarcoma invasion and metastasis. PMID:25823818

  4. Hepatitis B Virus HBx Protein Activation of Cyclin A–Cyclin-Dependent Kinase 2 Complexes and G1 Transit via a Src Kinase Pathway

    PubMed Central

    Bouchard, Michael; Giannakopoulos, Stavros; Wang, Edith H.; Tanese, Naoko; Schneider, Robert J.

    2001-01-01

    Numerous studies have demonstrated that the hepatitis B virus HBx protein stimulates signal transduction pathways and may bind to certain transcription factors, particularly the cyclic AMP response element binding protein, CREB. HBx has also been shown to promote early cell cycle progression, possibly by functionally replacing the TATA-binding protein-associated factor 250 (TAFII250), a transcriptional coactivator, and/or by stimulating cytoplasmic signal transduction pathways. To understand the basis for early cell cycle progression mediated by HBx, we characterized the molecular mechanism by which HBx promotes deregulation of the G0 and G1 cell cycle checkpoints in growth-arrested cells. We demonstrate that TAFII250 is absolutely required for HBx activation of the cyclin A promoter and for promotion of early cell cycle transit from G0 through G1. Thus, HBx does not functionally replace TAFII250 for transcriptional activity or for cell cycle progression, in contrast to a previous report. Instead, HBx is shown to activate the cyclin A promoter, induce cyclin A–cyclin-dependent kinase 2 complexes, and promote cycling of growth-arrested cells into G1 through a pathway involving activation of Src tyrosine kinases. HBx stimulation of Src kinases and cyclin gene expression was found to force growth-arrested cells to transit through G1 but to stall at the junction with S phase, which may be important for viral replication. PMID:11287574

  5. Activating transcription factor 3 (ATF3) expression is increased in erythema multiforme and is regulated by IFN-gamma in human keratinocytes.

    PubMed

    Pollack, Brian P; Sapkota, Bishu; Haun, Paul L

    2010-08-01

    Activating transcription factor 3 (ATF3) expression is increased in erythema multiforme and is regulated by IFN-gamma in human keratinocytes. Experimental Dermatology 2010; 19: e310-e313. Abstract: Activating transcription factor 3 (ATF3) is a member of the ATF/cyclic AMP responsive element-binding protein (CREB) family of transcription factors and is involved in the regulation of immune responses, apoptosis, DNA repair and oncogenesis. The epidermal expression of ATF3 in the setting of cutaneous inflammation has not been well characterized. To examine the expression of ATF3 in the setting of inflammatory skin disease, ATF3 protein expression was analysed by immunohistochemistry (IHC). We found diffuse epidermal ATF3 protein expression in skin biopsies of erythema multiforme (EM). Given the role of interferon (IFN)-gamma in erythema multiforme, we sought to examine the impact of IFN-gamma on ATF3 expression in human keratinocytes. IFN-gamma induced ATF3 mRNA and protein in primary human keratinocytes and HaCaT cells. Thus, epidermal ATF3 expression can be increased in the setting of inflammatory skin diseases and is regulated by IFN-gamma in human keratinocytes. PMID:20002170

  6. Active thermal isolation for temperature responsive sensors

    NASA Technical Reports Server (NTRS)

    Martinson, Scott D. (inventor); Gray, David L. (inventor); Carraway, Debra L. (inventor); Reda, Daniel C. (inventor)

    1994-01-01

    The detection of flow transition between laminar and turbulent flow and of shear stress or skin friction of airfoils is important in basic research for validation of airfoil theory and design. These values are conventionally measured using hot film nickel sensors deposited on a polyimide substrate. The substrate electrically insulates the sensor and underlying airfoil but is prevented from thermally isolating the sensor by thickness constraints necessary to avoid flow contamination. Proposed heating of the model surface is difficult to control, requires significant energy expenditures, and may alter the basic flow state of the airfoil. A temperature responsive sensor is located in the airflow over the specified surface of a body and is maintained at a constant temperature. An active thermal isolator is located between this temperature responsive sensor and the specific surface of the body. The total thickness of the isolator and sensor avoid any contamination of the flow. The temperature of this isolator is controlled to reduce conductive heat flow from the temperature responsive sensor to the body. This temperature control includes (1) operating the isolator at the same temperature as the constant temperature of the sensor; and (2) establishing a fixed boundary temperature which is either less than or equal to, or slightly greater than the sensor constant temperature. The present invention accordingly thermally isolates a temperature responsive sensor in an energy efficient, controllable manner while avoiding any contamination of the flow.

  7. Metabolic responses to simulated extravehicular activity

    NASA Technical Reports Server (NTRS)

    Williamson, Rebecca C.; Sharer, Peter J.; Webbon, Bruce W.; Rendon, Lisa R.

    1992-01-01

    Automatic control of the liquid cooling garment (LCG) worn by astronauts during extravehicular activity (EVA) would more efficiently regulate astronaut thermal comfort and improve astronaut productivity. An experiment was conducted in which subjects performed exercise profiles on a unique, supine upper body ergometer to elicit physiological and thermal responses similar to those achieved during zero-g EVAs. Results were analyzed to quantify metabolic rate, various body temperatures, and other heat balance parameters. Such data may lead to development of a microprocessor-based system to automatically maintain astronaut heat balance during extended EVAs.

  8. [Role of "secondary transmitters" in the exocrine function of the pancreas].

    PubMed

    Domshke, V; Konturek, S Ia; Domshke, S

    1981-03-01

    In animals, exogenous secretin produces dose--related increases in pancreatic tissue levels of cyclic AMP which are closely correlated with both bicarbonate and cyclic AMP outputs in pancreatic juice. These effects can be augmented by additional administration of phosphodiesterase inhibitors such as methylxanthines. Vasoactive intestinal peptide (VIP) produces similar though less pronounced effects than secretin. Following secretion or VIP the changes in pancreatic tissue cyclic AMP concentrations precede the physiological response, i.e. enhance water and electrolyte secretion. In man, bicarbonate and cyclic AMP concentrations of pure pancreatic juice obtained by endoscopic cannulation of Vater's papilla are significantly correlated in response to both secretin and VIP. VIP however, has a lower efficacy and potency relative to secretin. There is no significant correlation between pancreatic juice cyclic GMP and bicarbonate concentrations or outputs. These observations suggest that cyclic AMP plays an important role in mediating the stimulatory effects of secretin and VIP on hydrokinetic pancreatic exocrine function. However, it still remains to be elucidated in which specific way cyclic AMP initiates the secretory process. In principle, the action of cyclic nucleotides on cell function is thought to occur from their ability to activate cyclic nucleotide--dependent protein kinases which in turn are capable of activating enzymes of protein synthesis by phosphorylation (19). With respect to pancreatic secretion, studies of this kind are currently under way. PMID:6265294

  9. Role of convergent activation of glutamatergic and dopaminergic systems in the nucleus accumbens in the development of methamphetamine psychosis and dependence.

    PubMed

    Miyazaki, Masayuki; Noda, Yukihiro; Mouri, Akihiro; Kobayashi, Kazuto; Mishina, Masayoshi; Nabeshima, Toshitaka; Yamada, Kiyofumi

    2013-07-01

    Methamphetamine (Meth) abuse can result in long-lasting psychosis and dependence. The nucleus accumbens (NAc), which controls psychomotor and reward behaviours, is an important interface between the limbic system and receives convergent projections from dopaminergic and glutamatergic terminals. This study investigated the involvements of dopaminergic and glutamatergic transmission in the development of Meth psychosis and dependence by using tyrosine hydroxylase heterozygous mutant (TH+/-) mice and N-methyl-d-aspartate receptor knockout (NR2A-/-) mice. Repeated treatment with Meth (1 mg/kg s.c.) for 7 d in wild-type mice led to the development of behavioural abnormalities such as hyperactivity, sensory motor gating deficits and place preference. Associated with the behavioural changes, repeated treatment with Meth led to protein kinase A activation and phosphorylation of Ca2+/calmodulin kinase II and cyclic AMP response element binding protein in the NAc. In contrast, TH+/- and NR2A-/- mice displayed neither behavioural abnormalities nor activation of intracellular signalling pathways in the NAc. These results suggest that both dopaminergic and glutamatergic transmission play a crucial role in the development of Meth psychosis and dependence, which are associated with convergent activation of intracellular signalling pathways in the NAc. PMID:23195702

  10. The Freeze-Thaw Stress Response of the Yeast Saccharomyces cerevisiae Is Growth Phase Specific and Is Controlled by Nutritional State via the RAS-Cyclic AMP Signal Transduction Pathway

    Microsoft Academic Search

    JONG-IN PARK; CHRIS M. GRANT; PAUL V. ATTFIELD; IAN W. DAWES

    was frozen at 220°C for 2 h (cooling rate, less than 4°C min21) and thawed on ice for 40 min. Supercooling occurred without reducing cell survival and was followed by freezing. Loss of viability was proportional to the freezing duration, indicating that freezing is the main determinant of freeze-thaw damage. Regardless of the carbon source used, the wild-type strain and

  11. Influenza matrix protein 2 alters CFTR expression and function through its ion channel activity

    PubMed Central

    Londino, James D.; Lazrak, Ahmed; Jurkuvenaite, Asta; Collawn, James F.; Noah, James W.

    2013-01-01

    The human cystic fibrosis transmembrane conductance regulator (CFTR) is a cyclic AMP-activated chloride (Cl?) channel in the lung epithelium that helps regulate the thickness and composition of the lung epithelial lining fluid. We investigated whether influenza M2 protein, a pH-activated proton (H+) channel that traffics to the plasma membrane of infected cells, altered CFTR expression and function. M2 decreased CFTR activity in 1) Xenopus oocytes injected with human CFTR, 2) epithelial cells (HEK-293) stably transfected with CFTR, and 3) human bronchial epithelial cells (16HBE14o?) expressing native CFTR. This inhibition was partially reversed by an inhibitor of the ubiquitin-activating enzyme E1. Next we investigated whether the M2 inhibition of CFTR activity was due to an increase of secretory organelle pH by M2. Incubation of Xenopus oocytes expressing CFTR with ammonium chloride or concanamycin A, two agents that alkalinize the secretory pathway, inhibited CFTR activity in a dose-dependent manner. Treatment of M2- and CFTR-expressing oocytes with the M2 ion channel inhibitor amantadine prevented the loss in CFTR expression and activity; in addition, M2 mutants, lacking the ability to transport H+, did not alter CFTR activity in Xenopus oocytes and HEK cells. Expression of an M2 mutant retained in the endoplasmic reticulum also failed to alter CFTR activity. In summary, our data show that M2 decreases CFTR activity by increasing secretory organelle pH, which targets CFTR for destruction by the ubiquitin system. Alteration of CFTR activity has important consequences for fluid regulation and may potentially modify the immune response to viral infection. PMID:23457187

  12. Rapamycin induces mitogen-activated protein (MAP) kinase phosphatase-1 (MKP-1) expression through activation of protein kinase B and mitogen-activated protein kinase kinase pathways.

    PubMed

    Rastogi, Ruchi; Jiang, Zhongliang; Ahmad, Nisar; Rosati, Rita; Liu, Yusen; Beuret, Laurent; Monks, Robert; Charron, Jean; Birnbaum, Morris J; Samavati, Lobelia

    2013-11-22

    Mitogen-activated protein kinase phosphatase-1 (MKP-1), also known as dual specificity phosphatase-1 (DUSP-1), plays a crucial role in the deactivation of MAPKs. Several drugs with immune-suppressive properties modulate MKP-1 expression as part of their mechanism of action. We investigated the effect of mTOR inhibition through rapamycin and a dual mTOR inhibitor (AZD2014) on MKP-1 expression. Low dose rapamycin led to a rapid activation of both AKT and ERK pathways with a subsequent increase in MKP-1 expression. Rapamycin treatment led to phosphorylation of CREB, transcription factor 1 (ATF1), and ATF2, three transcription factors that bind to the cyclic AMP-responsive elements on the Mkp-1 promoter. Inhibition of either the MEK/ERK or the AKT pathway attenuated rapamycin-mediated MKP-1 induction. AZD2014 did not activate AKT but activated the ERK pathway, leading to a moderate MKP-1 induction. Using bone marrow-derived macrophages (BMDMs) derived from wild-type (WT) mice or mice deficient in AKT1 and AKT2 isoforms or BMDM from targeted deficiency in MEK1 and MEK2, we show that rapamycin treatment led to an increased MKP1 expression in BMDM from WT but failed to do so in BMDMs lacking the AKT1 isoform or MEK1 and MEK2. Importantly, rapamycin pretreatment inhibited LPS-mediated p38 activation and decreased nitric oxide and IL-6 production. Our work provides a conceptual framework for the observed immune modulatory effect of mTOR inhibition. PMID:24126911

  13. DNA binding activity of transcription factors in bronchial cells of horses with recurrent airway obstruction.

    PubMed

    Couëtil, Laurent L; Art, Tatiana; de Moffarts, Brieuc; Becker, Martine; Mélotte, Dorothée; Jaspar, Fabrice; Bureau, Fabrice; Lekeux, Pierre

    2006-09-15

    Horses with recurrent airway obstruction (RAO) present many similarities with human asthmatics including airway inflammation, hyperresponsiveness, reversible obstruction, and increased NF-kappaB expression. Studies in experimental asthma models have shown that transcriptions factors such as activator protein-1 (AP-1), GATA-3, cyclic AMP response element binding protein (CREB) and CAAT/enhancer binding protein (C/EBP) may also play an important role in airway inflammation. The purpose of this study was to measure DNA binding activity of these transcription factors in the airways of horses with RAO and to compare it to pulmonary function and bronchoalveolar lavage fluid (BALF) cytology. Seven horses with RAO and six control animals were studied during a moldy hay challenge and after 2 months at pasture. Pulmonary function, BALF cytology and transcription factors' activities in bronchial brushings were measured during hay and pasture exposures. During moldy hay challenge, RAO-affected horses developed severe airway obstruction and inflammation and a significantly higher airway AP-1 binding activity than in controls. After 2 months on pasture, pulmonary function and airway AP-1 binding activity were not different between RAO and control horses. The DNA binding activity of CREB in airways of RAO-affected horses increased significantly after 2 months at pasture and became higher than in controls. A significant positive correlation was detected between AP-1 binding activity and indicators of airway obstruction and inflammation. Airway GATA-3, CEBP and CREB binding activities were negatively correlated with indices of airway obstruction. However, contrarily to CREB binding activity, GATA-3 and CEBP binding activities were not different between RAO and control horses and were unaffected by changes in environment. These data support the view that AP-1 and CREB play a role in modulating airway inflammation in horses with RAO. PMID:16753225

  14. 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

    Microsoft Academic Search

    R. S. Scroggs

    2011-01-01

    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

  15. Up-regulation of circulating hemocyte population in response to bacterial challenge is mediated by octopamine and 5-hydroxytryptamine via Rac1 signal in Spodoptera exigua.

    PubMed

    Kim, Geun Seob; Kim, Yonggyun

    2010-06-01

    Bacterial challenge induced a significant increase in the total hemocyte population within 4h in the beet armyworm, Spodoptera exigua. Octopamine and 5-hydroxytryptamine (5-HT) are known to play critical roles in mediating insect immune responses. This study analyzed the effects of both biogenic monoamines on mediating up-regulation of circulating hemocyte population in response to bacterial challenge. Injection of either octopamine or 5-HT induced a significant increase in the total hemocyte count in the hemolymph without any bacterial challenge. On the other hand, the monoamine antagonists, phentolamine (an octopamine antagonist) and ketanserin (a 5-HT antagonist) each suppressed the increase of the circulating hemocyte counts in response to bacterial challenge. This rapid change of circulating hemocyte population did not appear to be the result of de novo hemocyte production from the hematopoietic organ because a physical block ("ligation") of hemolymph circulation between thorax and abdomen did not inhibit the increase of hemocyte counts in the isolated abdomen in response to bacterial challenge. The effects of the two monoamines on hemocyte numbers were not dependent on the mediatory effects of eicosanoids, because dexamethasone, an eicosanoid biosynthesis inhibitor, had no effect on the hemocyte recruitment induced by the monoamines. On the other hand, an adenylate cyclase inhibitor, NKY80, significantly impaired hemocyte mobilization in response to bacterial challenge, implying involvement of cyclic AMP in the control of hemocyte numbers. Also, a Rac1 inhibitor, NSC23766, significantly antagonized the effects of monoamines in increasing circulating hemocyte numbers. Rac1 activity was necessary to form F-actins in the hemocytes of S. exigua, where its activity showed a quantitative correlation with hemocyte-spreading behavior. This study suggests that octopamine and 5-HT mediate a rapid increase of circulating hemocyte population in response to bacterial challenge via Rac1 signal in S. exigua. PMID:19961854

  16. A PKA activity sensor for quantitative analysis of endogenous GPCR signaling via 2-photon FRET-FLIM imaging

    PubMed Central

    Chen, Yao; Saulnier, Jessica L.; Yellen, Gary; Sabatini, Bernardo L.

    2014-01-01

    Neuromodulators have profound effects on behavior, but the dynamics of their intracellular effectors has remained unclear. Most neuromodulators exert their function via G-protein-coupled receptors (GPCRs). One major challenge for understanding neuromodulator action is the lack of dynamic readouts of the biochemical signals produced by GPCR activation. The adenylate cyclase/cyclic AMP/protein kinase A (PKA) module is a central component of such biochemical signaling. This module is regulated by several behaviorally important neuromodulator receptors. Furthermore, PKA activity is necessary for the induction of many forms of synaptic plasticity as well as for the formation of long-term memory. In order to monitor PKA activity in brain tissue, we have developed a 2-photon fluorescence lifetime imaging microscopy (2pFLIM) compatible PKA sensor termed FLIM-AKAR, which is based on the ratiometric FRET sensor AKAR3. FLIM-AKAR shows a large dynamic range and little pH sensitivity. In addition, it is a rapidly diffusible cytoplasmic protein that specifically reports net PKA activity in situ. FLIM-AKAR expresses robustly in various brain regions with multiple transfection methods, can be targeted to genetically identified cell types, and responds to activation of both endogenous GPCRs and spatial-temporally specific delivery of glutamate. Initial experiments reveal differential regulation of PKA activity across subcellular compartments in response to neuromodulator inputs. Therefore, the reporter FLIM-AKAR, coupled with 2pFLIM, enables the study of PKA activity in response to neuromodulator inputs in genetically identified neurons in the brain, and sheds light on the intracellular dynamics of endogenous GPCR activation. PMID:24765076

  17. Desensitization of prostacyclin responsiveness in a neuronal hybrid cell line: selective loss of high affinity receptors.

    PubMed Central

    Leigh, P. J.; MacDermot, J.

    1985-01-01

    The binding of [3H]-iloprost (ZK36374) to NCB-20 membranes revealed a single population of high affinity receptors (KD = 9.55 nM, Bmax = 431 fmol mg-1 protein) and a low affinity, non-saturable binding component. Desensitization of prostacyclin-responsiveness of NCB-20 cells is induced by culture in the presence of the stable prostacyclin analogue carbacyclin. Desensitization is accompanied by an increase in the Kact value for prostacyclin (64.1 nM to 175 nM), and a reduction in the prostacyclin-dependent increase in adenylate cyclase activity (41.2 to 15.1 pmol cyclic AMP min-1 mg-1 protein). Desensitization is not accompanied by changes in the coupling of the catalytic (C) to the regulatory (Ns) subunit of adenylate cyclase. In addition, the physical identity of the receptor molecule (as characterized by its sensitivity to electron bombardment in the beam of a linear accelerator) is not changed by desensitization. Desensitization of prostacyclin-dependent activation of adenylate cyclase may be explained most simply by a loss of prostacyclin receptors. The anomalous increase in the Kact (concentration of prostaglandin giving half-maximum enzyme activation) for prostacyclin-stimulated adenylate cyclase was not accompanied by a substantial change in the KD of [3H]-iloprost binding, and is explained by a loss of spare receptors. Prostacyclin responsiveness in non-dividing cells may be restored after desensitization by prolonged culture (up to 48 h) in the absence of carbacyclin. Resensitization is accompanied by restoration of the high affinity Kact value (143 nM to 45.5 nM), and is dependent on de novo protein synthesis. PMID:2992650

  18. Macrophage membrane glycoprotein binding of Griffonia simplicifolia I-B4 induces TNF-alpha production and a tumoricidal response.

    PubMed

    Tabor, D R; Theus, S A; Barnett, J B; Jacobs, R F

    1992-09-01

    Thioglycollate-elicited macrophages (m phi), upon binding the lectin Griffonia simplicifolia IB4 (GSIB4) at the plasma membrane, are induced to secrete several low molecular weight proteins. In this investigation, results from specific ELISA and immunoprecipitation analysis of these molecules confirmed that the cytokine, tumor necrosis factor-alpha (TNF-alpha), belongs to the group of elicited proteins. This specific m phi response is directly influenced by the dose of GSIB4 used and the time in contact with the cells. At 40 micrograms/ml GSIB4, the maximum dose of lectin used, the m phi activity was equal to that achieved when the cells were incubated with an interferon-gamma/lipopolysaccharide (IFN/LPS) stimulus alone. Moreover, the data showed that TNF-mediated tumoricidal activity was significantly influenced by GSIB4 binding to the m phi membrane. When the lectin was incubated alone or in sequence with IFN/LPS, this ligand-receptor binding promoted the lysis of WEHI 164 tumor target cells. However, concurrent incubation of both IFN/LPS and GSIB4 with m phi significantly diminished the tumoricidal response. This suggested that one of the metabolic pathways utilized subsequent to receptor-ligand binding was altered by these interactions. When cyclic AMP (cAMP) and inositol triphosphate (IP3) levels were examined, the results showed that the concentration of cAMP was unchanged despite the fact that IP3 levels were significantly enhanced upon m phi-GSIB4 binding. Collectively, the data show that GSIB4 binding to specific glycoproteins in the m phi membrane induces TNF-alpha production and facilitates TNF-alpha dependent tumoricidal responses. It also appears that the transduction of the signal, in part, at least utilizes the phosphatidyl inositol pathway. Finally, it is noteworthy that m phi activity is influenced by the sequence in which GSIB4 is presented to the m phi relative to the IFN/LPS treatment. PMID:1324245

  19. Actions of adenosine A1 and A2 receptor antagonists on CFTR antibody-inhibited ?-adrenergic mucin secretion response

    PubMed Central

    Pereira, M M C; Lloyd Mills, C; Dormer, R L; McPherson, M A

    1998-01-01

    The cystic fibrosis gene protein, the cystic fibrosis transmembrane conductance regulator (CFTR) acts as a chloride channel and is a key regulator of mucin secretion. The mechanism by which 3-isobutyl-1-methylxanthine (IBMX) corrects the defect in CFTR mediated ?-adrenergic stimulation of mucin secretion has not been determined. The present study has investigated the actions of adenosine A1 and A2 receptor antagonists to determine whether ability to stimulate mucin secretion correlates with correction of CFTR antibody inhibited ?-adrenergic response and whether excessive cyclic AMP rise is required.CFTR antibodies were introduced into living rat submandibular acini by hypotonic swelling. Following recovery, mucin secretion in response to isoproterenol was measured.The adenosine A1 receptor antagonist, 8 cyclopentyltheophylline (CPT) was a less potent stimulator of mucin secretion than was the A2 receptor antagonist dimethylpropargylxanthine (DMPX). A concentration of CPT close to the Ki for A1 receptor antagonism (10?nM) did not stimulate mucin secretion.DMPX, although a potent stimulator of mucin secretion, did not correct CFTR antibody inhibited mucin secretion.CPT corrected defective CFTR antibody inhibited mucin secretion at a high (1?mM) concentration, suggesting a mechanism other than adenosine receptor antagonism.DMPX potentiated the isoproterenol induced cyclic AMP rise, whereas CPT did not.Correction of the defective CFTR mucin secretion response did not correlate with ability to stimulate mucin secretion and did not require potentiation of ?-adrenergic induced increases in cyclic AMP. This affords real promise for the development of a selective drug treatment for cystic fibrosis. PMID:9831904

  20. An Overview of the Environmental Response Team's Air Surveillance Procedures at Emergency Response Activities.

    ERIC Educational Resources Information Center

    Turpin, Rodney D.; Campagna, Philip

    1991-01-01

    Describes the United States Environmental Protection Agency's program for analytical response to chemical spills. Discusses the role and activities of the Environmental Response Team and the Safety and Air Surveillance Section (SASS). Describes SASS equipment and procedures. Provides case studies that demonstrate emergency response activities.…

  1. Mice expressing constitutively active Gsalpha exhibit stimulus encoding deficits similar to those observed in schizophrenia patients.

    PubMed

    Maxwell, C R; Liang, Y; Kelly, M P; Kanes, S J; Abel, T; Siegel, S J

    2006-09-01

    People with schizophrenia display sensory encoding deficits across a broad range of electrophysiological and behavioral measures, suggesting fundamental impairments in the ability to transduce the external environment into coherent neural representations. This inability to create basic components of complex stimuli interferes with a high fidelity representation of the world and likely contributes to cognitive deficits. The current study evaluates the effects of constitutive forebrain activation of the G(s)alpha G-protein subunit on auditory threshold and gain using acoustic brainstem responses and cortically generated N40 event-related potentials to assess the role of cyclic AMP signaling in sensory encoding. Additionally, we examine the ability of pharmacological treatments that mimic (amphetamine) or ameliorate (haloperidol) positive symptoms of schizophrenia to test the hypothesis that the encoding deficits observed in G(s)alpha transgenic mice can be normalized with treatment. We find that G(s)alpha transgenic mice have decreased amplitude of cortically generated N40 but normal acoustic brainstem response amplitude, consistent with forebrain transgene expression and a schizophrenia endophenotype. Transgenic mice also display decreased stimulus intensity response (gain) in both acoustic brainstem response and N40, indicating corticofugal influence on regions that lack transgene expression. N40 deficits in transgenic animals were ameliorated with low dose haloperidol and reversed with higher dose, suggesting dopamine D2 receptor-linked Gi activity contributes to the impairment. Consistent with this hypothesis, we recreated the G(s)alpha transgenic deficit in wild type animals using the indirect dopamine agonist amphetamine. This transgenic model of sensory encoding deficits provides a foundation for identifying biochemical contributions to sensory processing impairments associated with schizophrenia. PMID:16750890

  2. T3-induced liver AMP-activated protein kinase signaling: Redox dependency and upregulation of downstream targets

    PubMed Central

    Videla, Luis A; Fernández, Virginia; Cornejo, Pamela; Vargas, Romina; Morales, Paula; Ceballo, Juan; Fischer, Alvaro; Escudero, Nicolás; Escobar, Oscar

    2014-01-01

    AIM: To investigate the redox dependency and promotion of downstream targets in thyroid hormone (T3)-induced AMP-activated protein kinase (AMPK) signaling as cellular energy sensor to limit metabolic stresses in the liver. METHODS: Fed male Sprague-Dawley rats were given a single ip dose of 0.1 mg T3/kg or T3 vehicle (NaOH 0.1 N; controls) and studied at 8 or 24 h after treatment. Separate groups of animals received 500 mg N-acetylcysteine (NAC)/kg or saline ip 30 min prior T3. Measurements included plasma and liver 8-isoprostane and serum ?-hydroxybutyrate levels (ELISA), hepatic levels of mRNAs (qPCR), proteins (Western blot), and phosphorylated AMPK (ELISA). RESULTS: T3 upregulates AMPK signaling, including the upstream kinases Ca2+-calmodulin-dependent protein kinase kinase-? and transforming growth factor-?-activated kinase-1, with T3-induced reactive oxygen species having a causal role due to its suppression by pretreatment with the antioxidant NAC. Accordingly, AMPK targets acetyl-CoA carboxylase and cyclic AMP response element binding protein are phosphorylated, with the concomitant carnitine palmitoyltransferase-1? (CPT-1?) activation and higher expression of peroxisome proliferator-activated receptor-? co-activator-1? and that of the fatty acid oxidation (FAO)-related enzymes CPT-1?, acyl-CoA oxidase 1, and acyl-CoA thioesterase 2. Under these conditions, T3 induced a significant increase in the serum levels of ?-hydroxybutyrate, a surrogate marker for hepatic FAO. CONCLUSION: T3 administration activates liver AMPK signaling in a redox-dependent manner, leading to FAO enhancement as evidenced by the consequent ketogenic response, which may constitute a key molecular mechanism regulating energy dynamics to support T3 preconditioning against ischemia-reperfusion injury. PMID:25516653

  3. Synaptic Background Activity Enhances the Responsiveness of Neocortical Pyramidal Neurons

    E-print Network

    Destexhe, Alain

    Synaptic Background Activity Enhances the Responsiveness of Neocortical Pyramidal Neurons NICOLAS H the responsiveness of neocortical pyramidal neurons. J Neu- rophysiol 84: 1488­1496, 2000. Neocortical pyramidal in morphologically reconstructed neocortical pyramidal neurons in which synaptic back- ground activity was simulated

  4. Pre- and poststimulus activation of response channels: a psychophysiological analysis.

    PubMed

    Gratton, G; Coles, M G; Sirevaag, E J; Eriksen, C W; Donchin, E

    1988-08-01

    To examine mechanisms of response activation, we asked subjects to respond differentially to the central letter of one of four arrays--HHHHH, SSHSS, SSSSS, and HHSHH--and measured event-related brain potentials (ERPs) and electromyographic activity (EMG). For very fast responses, accuracy was at chance level for all arrays, suggesting that subjects were guessing. For intermediate latency responses, accuracy was above chance if the noise was compatible with the targets and below chance if it was incompatible, suggesting that these responses were based on partial stimulus analysis. For slow responses, accuracy was above chance for all arrays, suggesting that these responses were based on complete stimulus analysis. The occurrence and accuracy of fast responses could be predicted by examining motor potentials preceding the presentation of the array. Measures of the motor potentials in the period following the presentation of the array suggested that partial analysis of stimulus information could activate responses and that the level of response activation at the time of the EMG response was constant for trials with different response latencies. The data are discussed in terms of a response channel conception. PMID:2971764

  5. Inflammasome Activation in Response to Eukaryotic Pathogens

    Microsoft Academic Search

    Olaf Gross; Christina J. Thomas; Laura E. Layland

    \\u000a Inflammasomes are multi-protein complexes that serve as platforms for caspase-1 activation and subsequent proteolytic maturation\\u000a of interleukin 1? (IL-1?) within innate immune cells. The Nlrp3 inflammasome is the most fully characterised. It is activated\\u000a by various endogenous and exogenous danger signals such as environmental irritants, signals of tissue damage and pathogens.\\u000a The broad spectrum of activators is reflected at the

  6. A-kinase-anchoring proteins coordinate inflammatory responses to cigarette smoke in airway smooth muscle.

    PubMed

    Poppinga, Wilfred J; Heijink, Irene H; Holtzer, Laura J; Skroblin, Philipp; Klussmann, Enno; Halayko, Andrew J; Timens, Wim; Maarsingh, Harm; Schmidt, Martina

    2015-04-15

    ?2-Agonist inhibitors can relieve chronic obstructive pulmonary disease (COPD) symptoms by stimulating cyclic AMP (cAMP) signaling. A-kinase-anchoring proteins (AKAPs) compartmentalize cAMP signaling by establishing protein complexes. We previously reported that the ?2-agonist fenoterol, direct activation of protein kinase A (PKA), and exchange factor directly activated by cAMP decrease cigarette smoke extract (CSE)-induced release of neutrophil attractant interleukin-8 (IL-8) from human airway smooth muscle (ASM) cells. In the present study, we tested the role of AKAPs in CSE-induced IL-8 release from ASM cells and assessed the effect of CSE on the expression levels of different AKAPs. We also studied mRNA and protein expression of AKAPs in lung tissue from patients with COPD. Our data show that CSE exposure of ASM cells decreases AKAP5 and AKAP12, both capable of interacting with ?2-adrenoceptors. In lung tissue of patients with COPD, mRNA levels of AKAP5 and AKAP12 were decreased compared with lung tissue from controls. Using immunohistochemistry, we detected less AKAP5 protein in ASM of patients with COPD Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II compared with control subjects. St-Ht31, which disrupts AKAP-PKA interactions, augmented CSE-induced IL-8 release from ASM cells and diminished its suppression by fenoterol, an effect mediated by disturbed ERK signaling. The modulatory role of AKAP-PKA interactions in the anti-inflammatory effects of fenoterol in ASM cells and the decrease in expression of AKAP5 and AKAP12 in response to cigarette smoke and in lungs of patients with COPD suggest that cigarette smoke-induced changes in AKAP5 and AKAP12 in patients with COPD may affect efficacy of pharmacotherapy. PMID:25637608

  7. Magnetogastrographic detection of gastric electrical response activity in humans

    Microsoft Academic Search

    Andrei Irimia; William O Richards; L Alan Bradshaw

    2006-01-01

    The detection and characterization of gastric electrical activity has important clinical applications, including the early diagnosis of gastric diseases in humans. In mammals, this phenomenon has two important features: an electrical control activity (ECA) that manifests itself as an electric slow wave (with a frequency of 3 cycles per minute in humans) and an electrical response activity (ERA) that is

  8. ON THE ACTIVE RESPONSE OF SOFT LIVING TISSUES P. Nardinocchi

    E-print Network

    of activation of a cardiac muscle cell) and on the time­varying muscle fibre extension ratio. In [9 incompressible (visco-) elastic response; a key issue is the active nature of muscle fibres, in other words for are the complex distribution of the predominant orientation of muscle fibres across the tissues and the active

  9. The phosphorylation state of phosducin determines its ability to block transducin subunit interactions and inhibit transducin binding to activated rhodopsin.

    PubMed

    Yoshida, T; Willardson, B M; Wilkins, J F; Jensen, G J; Thornton, B D; Bitensky, M W

    1994-09-30

    Heterotrimeric GTP-binding proteins (G-proteins) serve many different signal transduction pathways. Phosducin, a 28-kDa phosphoprotein, is expressed in a variety of mammalian cell types and blocks activation of several classes of G-proteins. Phosphorylation of phosducin by cyclic AMP-dependent protein kinase prevents phosducin-mediated inhibition of G-protein GTPase activity (Bauer, P. H., Müller, S., Puzicha, M., Pippig, S., Obermaier, B., Helmreich, E. J. M., and Lohse, M. J. (1992) Nature 358, 73-76). In retinal rods, phosducin inhibits transducin (Gt) activation by binding its beta gamma subunits. While rod phosducin is phosphorylated in the dark and dephosphorylated after illumination (Lee, R.-H., Brown, B. M., and Lolley, R. N. (1984) Biochemistry 23, 1972-1977), the significance of these reactions is still unclear. The data presented here permit a more precise characterization of phosducin function and the consequences of its phosphorylation. Dephosphophosducin blocked binding of the Gt alpha 1 subunit to activated rhodopsin in the presence of stoichiometric amounts of Gt beta gamma, whereas phosphophosducin did not. Surprisingly, the binding affinity of phosphophosducin for Gt beta gamma was not significantly reduced compared with the binding affinity of dephosphophosducin. However, the association of phosducin with Gt beta gamma in a size exclusion column matrix was dependent on the phosphorylation state of phosducin. Moreover, the ability of phosducin to compete with Gt alpha for binding to Gt beta gamma was also dependent on the phosphorylation state of phosducin. No interaction was found between phosducin and Gt alpha. These data indicate that phosducin decreases rod responsiveness by binding to the beta gamma subunits of Gt and preventing their interaction with Gt alpha, thereby inhibiting Gt alpha activation by the activated receptor. Moreover, phosphorylation of phosducin blocks its ability to compete with Gt alpha for binding to Gt beta gamma. PMID:7929057

  10. The effects of the ?-agonist isoproterenol on the down-regulation, functional responsiveness, and trafficking of ?2-adrenergic receptors with amino-terminal polymorphisms

    PubMed Central

    Koryakina, Yulia; Jones, Stacie M.; Cornett, Lawrence E.; Seely, Kathryn; Brents, Lisa; Prather, Paul L.; Kofman, Alexander; Kurten, Richard C.

    2014-01-01

    The ?2-adrenergic receptor (?2AR) is an important target for respiratory and cardiovascular disease medications. Clinical studies suggest that amino-terminal polymorphisms of the ?2AR may act as disease modifiers. We hypothesized that polymorphisms at amino acids 16 and 27 result in differential trafficking and down-regulation of ?2AR variants following ?-agonist exposure. The functional consequences of the four possible combinations of these polymorphisms in the human ?2AR (designated ?2AR-RE, -GE, -RQ and -GQ) were studied using site-directed mutagenesis and recombinant expression in HEK 293 cells. Ligand binding assays demonstrated that after 24 h exposure to 1 ?M isoproterenol, isoforms with Arg16 (?2AR-RE and ?2AR-RQ) underwent increased down-regulation compared to isoforms with Gly16 (?2AR-GE and ?2AR-GQ). Consistent with these differences in down-regulation between isoforms, prolonged isoproterenol treatment resulted in diminished cyclic AMP response to subsequent isoproterenol challenge in ?2AR-RE relative to ?2AR-GE. Confocal microscopy revealed that the receptor isoforms had similar co-localization with the early endosomal marker EEA1 following isoproterenol treatment, suggesting that they had similar patterns of internalization. None of the isoforms exhibited significant co-localization with the recycling endosome marker Rab11 in response to isoproterenol treatment. Furthermore, we found that prolonged isoproterenol treatment led to a higher degree of co-localization of ?2AR-RE with the lysosomal marker Lamp1 compared to that of ?2AR-GE. Taken together, these results indicate that a mechanism responsible for differential responses of these receptor isoforms to ?-agonist involves differences in the efficiency with which agonist-activated receptors are trafficked to lysosomes for degradation, or differences in degradation in the lysosomes. PMID:22938397

  11. The Neurophysiology of Response Competition: Motor Cortex Activation and Inhibition following Subliminal Response Priming

    Microsoft Academic Search

    Peter Praamstra; Ellen Seiss

    2005-01-01

    Some widely used tasks in cognitive neuroscience depend on the induction of a response conflict between choice alternatives, involving partial activation of the incorrect response before the correct response is emitted. Although such conflict tasks are often used to investigate frontal-lobe-based conflict-monitoring processes, it is not known how response competition evolves in the motor cortex. To investigate the dynamics of

  12. Activation of codependent transcription factors is required for transcriptional induction of the vgf gene by nerve growth factor and Ras.

    PubMed Central

    D'Arcangelo, G; Habas, R; Wang, S; Halegoua, S; Salton, S R

    1996-01-01

    Nerve growth factor (NGF) treatment of PC12 cells leads to the elaboration of a neuronal phenotype, including the induction of neuronally expressed genes such as vgf. To study vgf transcription, we have created chimeric vgf/beta-globin genes in which vgf promoter sequences drive the expression of the beta-globin reporter gene or of a chimeric beta-globin gene fused to 3' untranslated vgf gene sequences. We have found that the level of inducibility of the latter construct by NGF resembles that of the endogenous vgf gene. Using transient transfection of the chimeric reporter genes into PC12 cells, into PC12 subclones expressing activated or dominantly interfering mutant Ras proteins, and into PC12 variants expressing specific NGF receptor/Trk mutants, we show that transcriptional regulation of the vgf promoter by NGF is mediated through a Ras-dependent signaling pathway. By mutational analysis of the vgf promoter, we have identified three promoter elements involved in mediating transcriptional induction by NGF and Ras. In addition to the cyclic AMP-responsive element (CRE), which binds to ATF-1, ATF-2, and CRE-binding protein in PC12 nuclear extracts, a novel CCAAT element and its binding proteins were identified, which, like the CRE, is necessary but not sufficient for the Ras-dependent induction of the vgf gene by NGF. We also identify a G(S)G element unusually located between the TATA box and transcriptional start site, which binds the NGF- and Ras-induced transcription factor, NGFI-A, and amplifies the transcriptional response. Integrating data from studies of vgf promoter regulation and NGF signal transduction, we present a model for vgf gene induction in which transcriptional activation is achieved through the persistent, direct activation of multiple interacting transcription factors binding to CRE and CCAAT elements, coordinated with the delayed transcription factor action at a G(S)G element resulting from the induced expression of NGFI-A. PMID:8756618

  13. SILENT STORM Distributed Active Response System for Cyber Defense

    E-print Network

    SILENT STORM ­ Distributed Active Response System for Cyber Defense Traditional intrusion detection the Ubiquitous Network Transient Autonomous Mission Entity (UNTAME) system developed at ORNL over the past 10 37831-6418 www.ioc.ornl.gov #12;

  14. IP receptor-dependent activation of PPAR{gamma} by stable prostacyclin analogues

    SciTech Connect

    Falcetti, Emilia [BHF Laboratories, Department of Medicine, Rayne Building, University College London, 5 University Street, London WC1E 6JF (United Kingdom); Flavell, David M. [BHF Laboratories, Department of Medicine, Rayne Building, University College London, 5 University Street, London WC1E 6JF (United Kingdom); Staels, Bart [Institut Pasteur de Lille, Departement d'Atherosclerose, Lille F-59019 (France); Inserm, U545, Lille F-59019 (France); Universite de Lille 2, Faculte de Pharmacie et Faculte de Medecine, Lille F-59006 (France); Tinker, Andrew [BHF Laboratories, Department of Medicine, Rayne Building, University College London, 5 University Street, London WC1E 6JF (United Kingdom); Haworth, Sheila G. [Institute of Child Health, Great Ormond Street Hospital, London (United Kingdom); Clapp, Lucie H. [BHF Laboratories, Department of Medicine, Rayne Building, University College London, 5 University Street, London WC1E 6JF (United Kingdom)]. E-mail: l.clapp@ucl.ac.uk

    2007-09-07

    Stable prostacyclin analogues can signal through cell surface IP receptors or by ligand binding to nuclear peroxisome proliferator-activated receptors (PPARs). So far these agents have been reported to activate PPAR{alpha} and PPAR{delta} but not PPAR{gamma}. Given PPAR{gamma} agonists and prostacyclin analogues both inhibit cell proliferation, we postulated that the IP receptor might elicit PPAR{gamma} activation. Using a dual luciferase reporter gene assay in HEK-293 cells stably expressing the IP receptor or empty vector, we found that prostacyclin analogues only activated PPAR{gamma} in the presence of the IP receptor. Moreover, the novel IP receptor antagonist, RO1138452, but not inhibitors of the cyclic AMP pathway, prevented activation. Likewise, the anti-proliferative effects of treprostinil observed in IP receptor expressing cells, were partially inhibited by the PPAR{gamma} antagonist, GW9662. We conclude that PPAR{gamma} is activated through the IP receptor via a cyclic AMP-independent mechanism and contributes to the anti-growth effects of prostacyclin analogues.

  15. Pythium infection activates conserved plant defense responses in mosses

    Microsoft Academic Search

    Juan Pablo Oliver; Alexandra Castro; Carina Gaggero; Tomas Cascón; Eric A. Schmelz; Carmen Castresana; Inés Ponce de León

    2009-01-01

    The moss Physcomitrella patens (P. patens) is a useful model to study abiotic stress responses since it is highly tolerant to drought, salt and osmotic stress. However,\\u000a very little is known about the defense mechanisms activated in this moss after pathogen assault. In this study, we show that\\u000a P. patens activated multiple and similar responses against Pythium irregulare and Pythium

  16. Pythium infection activates conserved plant defense responses in mosses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The moss Physcomitrella patens (P. patens) is a useful model to study abiotic stress responses since it is highly tolerant to drought, salt and osmotic stress. However, little is known about the defense mechanisms activated in this moss after pathogen assault. Here the induction of defense responses...

  17. Glucocorticoid-mediated inhibition of ornithine decarboxylyase activity in S49 lymphoma cells.

    PubMed Central

    Insel, P A; Honeysett, J M

    1981-01-01

    Incubation of wild-type S49 lymphoma cells with glucocorticoids, such as dexamethasone and hydrocortisone, inhibits the activity of ornithine decarboxylase (L-ornithine carboxylyase, EC 4.1.1.17), the rate-limiting enzyme in the pathway of polyamine biosynthesis. The kinetics of this inhibition are more rapid than the glucocorticoid-mediated growth arrest in the G1 phase of the cell cycle or in glucocorticoid-mediated cytolysis of these cells. The inhibition of ornithine decarboxylase activity by corticosteroids is specific for steroids of the glucocorticoid class. Results obtained with variant S49 cells having lesions in the pathways of glucocorticoid or cyclic AMP action indicate that cytoplasmic glucocorticoid receptors, as well as nuclear transfer of steroid--receptor complexes, are required for the inhibition of ornithine decarboxylase activity but that this inhibition does not require hormonal activation of adenylate cyclase or cyclic AMP-dependent protein kinase. Because glucocorticoid-mediated inhibition of ornithine decarboxylase occurs when cellular protein synthesis has decreased less than 20%, this inhibition may represent a specific glucocorticoid-mediated deinduction of ornithine decarboxylase in S49 cells. Inhibition of ornithine decarboxylase activity may offer a useful marker for suppression of growth and cell cycle progression in these and other lymphoma cells. Images PMID:6272311

  18. The neurophysiology of response competition: motor cortex activation and inhibition following subliminal response priming.

    PubMed

    Praamstra, Peter; Seiss, Ellen

    2005-03-01

    Some widely used tasks in cognitive neuroscience depend on the induction of a response conflict between choice alternatives, involving partial activation of the incorrect response before the correct response is emitted. Although such ''conflict tasks'' are often used to investigate frontal-lobe-based conflict-monitoring processes, it is not known how response competition evolves in the motor cortex. To investigate the dynamics of motor cortex activation during response competition, we used a subliminal priming task that induced response competition while bypassing pre-response stage processing conflict. Analyses of movement-related EEG potentials supported an interaction between competing responses characterized by reciprocal inhibition. Inhibitory interactions between response channels contribute to the resolution of response conflict. However, the reciprocal inhibition at motor cortex level seemed to operate independent of higher level conflict-monitoring processes, which were relatively insensitive to response conflict induced by subliminal priming. These results elucidate how response conflict causes interference as well as the conditions under which frontal-lobe-based interference control processes are engaged. PMID:15814007

  19. Fractalkine/CX3CL1 engages different neuroprotective responses upon selective glutamate receptor overactivation

    PubMed Central

    Lauro, Clotilde; Catalano, Myriam; Di Paolo, Eleonora; Chece, Giuseppina; de Costanzo, Ida; Trettel, Flavia; Limatola, Cristina

    2015-01-01

    Neuronal death induced by overactivation of N-methyl-d-aspartate receptors (NMDARs) is implicated in the pathophysiology of many neurodegenerative diseases such as stroke, epilepsy and traumatic brain injury. This toxic effect is mainly mediated by NR2B-containing extrasynaptic NMDARs, while NR2A-containing synaptic NMDARs contribute to cell survival, suggesting the possibility of therapeutic approaches targeting specific receptor subunits. We report that fractalkine/CX3CL1 protects hippocampal neurons from NMDA-induced cell death with a mechanism requiring the adenosine receptors type 2A (A2AR). This is different from CX3CL1-induced protection from glutamate (Glu)-induced cell death, that fully depends on A1R and requires in part A3R. We show that CX3CL1 neuroprotection against NMDA excitotoxicity involves D-serine, a co-agonist of NR2A/NMDAR, resulting in cyclic AMP-dependent transcription factor cyclic-AMP response element-binding protein (CREB) phosphorylation. PMID:25653593

  20. Response of the topside ionosphere to recurrent geomagnetic activity

    Microsoft Academic Search

    Jing Liu; Libo Liu; Biqiang Zhao; Weixing Wan; Roderick A. Heelis

    2010-01-01

    In the present study we investigate the solar activity, local time, and latitudinal dependence of the topside ionosphere response to recurrent geomagnetic activity, using 8 years (1998–2005) of data on total ion density (Ni) retrieved from Defense Meteorological Satellites Program observations at about 840 km altitude. It is the first attempt to explore the presence of oscillations in the topside

  1. Reindeer and caribou (Rangifer tarandus) response towards human activities

    Microsoft Academic Search

    We address the question of how human activities and infrastructure influence reindeer\\/caribou's (Rangifer tarandus) behaviour and habitat use and review studies based on current methodologies. Anthropogenic activities have a direct affect on Rangifer behaviour through the senses hearing, sight and smell, and all of these are important tools for behavioural risk assessment. Short term indirect responses, such as habituation, sensitisation,

  2. Effect of Global Regulators RpoS and Cyclic-AMP/CRP on the Catabolome and Transcriptome of Escherichia coli K12 during Carbon- and Energy-Limited Growth

    PubMed Central

    Egli, Thomas

    2015-01-01

    For heterotrophic microbes, limited availability of carbon and energy sources is one of the major nutritional factors restricting the rate of growth in most ecosystems. Physiological adaptation to this hunger state requires metabolic versatility which usually involves expression of a wide range of different catabolic pathways and of high-affinity carbon transporters; together, this allows for simultaneous utilization of mixtures of carbonaceous compounds at low concentrations. In Escherichia coli the stationary phase sigma factor RpoS and the signal molecule cAMP are the major players in the regulation of transcription under such conditions; however, their interaction is still not fully understood. Therefore, during growth of E. coli in carbon-limited chemostat culture at different dilution rates, the transcriptomes, expression of periplasmic proteins and catabolomes of strains lacking one of these global regulators, either rpoS or adenylate cyclase (cya), were compared to those of the wild-type strain. The inability to synthesize cAMP exerted a strong negative influence on the expression of alternative carbon source uptake and degradation systems. In contrast, absence of RpoS increased the transcription of genes belonging to high-affinity uptake systems and central metabolism, presumably due to reduced competition of ?D with ?S. Phenotypical analysis confirmed this observation: The ability to respire alternative carbon substrates and to express periplasmic high-affinity binding proteins was eliminated in cya and crp mutants, while these properties were not affected in the rpoS mutant. As expected, transcription of numerous stress defence genes was negatively affected by the rpoS knock-out mutation. Interestingly, several genes of the RpoS stress response regulon were also down-regulated in the cAMP-negative strain indicating a coordinated global regulation. The results demonstrate that cAMP is crucial for catabolic flexibility during slow, carbon-limited growth, whereas RpoS is primarily involved in the regulation of stress response systems necessary for the survival of this bacterium under hunger conditions. PMID:26204448

  3. Phosphoinositide and Erk signaling pathways mediate activity-driven rodent olfactory sensory neuronal survival and stress mitigation.

    PubMed

    Kim, So Yeun; Mammen, Alex; Yoo, Seung-Jun; Cho, Bongki; Kim, Eun-Kyoung; Park, Jong-In; Moon, Cheil; Ronnett, Gabriele V

    2015-08-01

    Olfactory sensory neurons (OSNs) are the initial site for olfactory signal transduction. Therefore, their survival is essential to olfactory function. In the current study, we demonstrated that while odorant stimulation promoted rodent OSN survival, it induced generation of reactive oxygen species in a dose- and time-dependent manner as well as loss of membrane potential and fragmentation of mitochondria. The MEK-Erk pathway played a critical role in mediating these events, as its inhibition decreased odorant stimulation-dependent OSN survival and exacerbated intracellular stress measured by reactive oxygen species generation and heat-shock protein 70 expression. The phosphoinositide pathway, rather than the cyclic AMP pathway, mediated the odorant-induced activation of the MEK-Erk pathway. These findings provide important insights into the mechanisms of activity-driven OSN survival, the role of the phosphoinositide pathway in odorant signaling, and demonstrate that odorant detection and odorant stimulation-mediated survival proceed via independent signaling pathways. This mechanism, which permits independent regulation of odorant detection from survival signaling, may be advantageous if not diminished by repeated or prolonged odor exposure. We investigated the role of odorant stimulation in generating cellular stress and the molecular mechanisms mitigating such stress and promoting neuronal survival. Odorant stimulation promoted olfactory sensory neuron (OSN) survival and also induced intracellular oxidative stress, which was exacerbated when MEK/Erks pathway was inhibited. Sensory stimulation simultaneously activated at least two parallel pathways, the AC/cAMP cascade responsible for odorant detection, and phosphoinositide hydrolysis to promote odorant stimulation-dependent neuronal survival odorants may activate parallel signaling cascades to mediate sensory detection and sensory stimulation-dependent survival. AC, adenylyl cyclase; cAMP, cyclic adenosine monophosphate; Erk, extracellular signal-regulated kinase; MEK, MAPK/ERK kinase. PMID:25903517

  4. Predicting Memory Training Response Patterns: Results From ACTIVE

    PubMed Central

    Rebok, George W.; Bandeen-Roche, Karen; Carlson, Michelle C.

    2009-01-01

    Previous research suggests that there is a great deal of variability among older adults' response to memory training. Using latent class analysis, we examined data from the memory training arm of the Advanced Cognitive Training for Independent and Vital Elderly Trial (ACTIVE), a large randomized controlled cognitive training trial, to determine if there were distinct patterns of responsiveness to training. Additionally, we examined whether baseline demographic and cognitive factors were predictive of these response patterns. The results indicate that among memory-trained participants, there are 3 distinct response patterns, suggesting that participants gravitate toward specific mnemonic techniques. Furthermore, baseline memory and speed of processing abilities, age, and education are predictive of these distinct response patterns. Taken together, the findings suggest that we can characterize and predict older adults' response to memory training. PMID:19196693

  5. Participation in Peer Response as Activity: An Examination of Peer Response Stances from an Activity Theory Perspective

    ERIC Educational Resources Information Center

    Zhu, Wei; Mitchell, Deborah A.

    2012-01-01

    This article reports a case study that examined English as a Second Language students' peer response stances from an activity theory perspective. More specifically, the study was guided by the constructs of activity and motive/object in Leont'ev's theory. Multiple sources of data were collected from two native Spanish-speaking students enrolled in…

  6. Overlapping CRE and E Box Motifs in the Enhancer Sequences of the Bovine Leukemia Virus 5? Long Terminal Repeat Are Critical for Basal and Acetylation-Dependent Transcriptional Activity of the Viral Promoter: Implications for Viral Latency

    PubMed Central

    Calomme, Claire; Dekoninck, Ann; Nizet, Séverine; Adam, Emmanuelle; Nguyên, Thi Liên-Anh; Van Den Broeke, Anne; Willems, Luc; Kettmann, Richard; Burny, Arsène; Lint, Carine Van

    2004-01-01

    Bovine leukemia virus (BLV) infection is characterized by viral latency in a large proportion of cells containing an integrated provirus. In this study, we postulated that mechanisms directing the recruitment of deacetylases to the BLV 5? long terminal repeat (LTR) could explain the transcriptional repression of viral expression in vivo. Accordingly, we showed that BLV promoter activity was induced by several deacetylase inhibitors (such as trichostatin A [TSA]) in the context of episomal LTR constructs and in the context of an integrated BLV provirus. Moreover, treatment of BLV-infected cells with TSA increased H4 acetylation at the viral promoter, showing a close correlation between the level of histone acetylation and transcriptional activation of the BLV LTR. Among the known cis-regulatory DNA elements located in the 5? LTR, three E box motifs overlapping cyclic AMP responsive elements (CREs) in U3 were shown to be involved in transcriptional repression of BLV basal gene expression. Importantly, the combined mutations of these three E box motifs markedly reduced the inducibility of the BLV promoter by TSA. E boxes are susceptible to recognition by transcriptional repressors such as Max-Mad-mSin3 complexes that repress transcription by recruiting deacetylases. However, our in vitro binding studies failed to reveal the presence of Mad-Max proteins in the BLV LTR E box-specific complexes. Remarkably, TSA increased the occupancy of the CREs by CREB/ATF. Therefore, we postulated that the E box-specific complexes exerted their negative cooperative effect on BLV transcription by steric hindrance with the activators CREB/ATF and/or their transcriptional coactivators possessing acetyltransferase activities. Our results thus suggest that the overlapping CRE and E box elements in the BLV LTR were selected during evolution as a novel strategy for BLV to allow better silencing of viral transcription and to escape from the host immune response. PMID:15564493

  7. Targeted Activation of Conventional and Novel Protein Kinases C through Differential Translocation Patterns

    PubMed Central

    Hui, Xin; Reither, Gregor; Kaestner, Lars

    2014-01-01

    Activation of the two ubiquitous families of protein kinases, protein kinase A (PKA) and protein kinase C (PKC), is thought to be independently coupled to stimulation of G?s and G?q, respectively. Live-cell confocal imaging of protein kinase C fluorescent protein fusion constructs revealed that simultaneous activation of G?s and G?q resulted in a differential translocation of the conventional PKC? to the plasma membrane while the novel PKC? was recruited to the membrane of the endoplasmic reticulum (ER). We demonstrate that the PKC? translocation was driven by a novel G?s-cyclic AMP-EPAC-RAP-PLC? pathway resulting in specific diacylglycerol production at the membrane of the ER. Membrane-specific phosphorylation sensors revealed that directed translocation resulted in phosphorylation activity confined to the target membrane. Specific stimulation of PKC? caused phosphorylation of the inositol-1,4,5-trisphosphate receptor and dampening of global Ca2+ signaling revealed by graded flash photolysis of caged inositol-1,4,5-trisphosphate. Our data demonstrate a novel signaling pathway enabling differential decoding of incoming stimuli into PKC isoform-specific membrane targeting, significantly enhancing the versatility of cyclic AMP signaling, thus demonstrating the possible interconnection between the PKA and PKC pathways traditionally treated independently. We thus provide novel and elementary understanding and insights into intracellular signaling events. PMID:24732802

  8. Differences in wearer response to garments for outdoor activity

    Microsoft Academic Search

    R. M. Laing; S. T. Sims; C. A. Wilson; B. E. Niven; N. M. Cruthers

    2008-01-01

    The performance of garments for outdoor activity was compared. Three fabrics, each in garments for the upper body, matched garment\\/wearer dimensions, were worn by 10 athletically ‘well-trained’ males under controlled conditions (hot 32 ± 2°C, 20 ± 2% relative humidity (RH); cold 8 ± 2°C, 40 ± 2% RH) with physical (instrumental) and sensory responses obtained during the trials. Differences in human responses to the fabrics\\/garments included heart

  9. Patterning of sympathetic nerve activity in response to vestibular stimulation

    NASA Technical Reports Server (NTRS)

    Kerman, I. A.; McAllen, R. M.; Yates, B. J.

    2000-01-01

    Growing evidence suggests a role for the vestibular system in regulation of autonomic outflow during postural adjustments. In the present paper we review evidence for the patterning of sympathetic nerve activity elicited by vestibular stimulation. In response to electrical activation of vestibular afferents, firing of sympathetic nerves located throughout the body is altered. However, activity of the renal nerve is most sensitive to vestibular inputs. In contrast, high-intensity simultaneous activation of cutaneous and muscle inputs elicits equivalent changes in firing of the renal, superior mesenteric and lumbar colonic nerves. Responses of muscle vasoconstrictor (MVC) efferents to vestibular stimulation are either inhibitory (Type I) or are comprised of a combination of excitation and inhibition (Type II). Interestingly, single MVC units located in the hindlimb exhibited predominantly Type I responses while those located in the forelimb and face exhibited Type II responses. Furthermore, brachial and femoral arterial blood flows were dissociated in response to vestibular stimulation, such that brachial vascular resistance increased while femoral resistance decreased. These studies demonstrate that vestibulosympathetic reflexes are patterned according to both the anatomical location and innervation target of a particular sympathetic nerve, and can lead to distinct changes in local blood flow.

  10. Ionizing radiation activates the Nrf2 antioxidant response

    PubMed Central

    McDonald, J. Tyson; Kim, Kwanghee; Norris, Andrew; Vlashi, Erina; Phillips, Tiffany M.; Lagadec, Chann; Donna, Lorenza Della; Ratikan, Josephine; Szelag, Heather; Hlatky, Lynn; McBride, William H.

    2010-01-01

    The transcription factor Nrf2 binds the antioxidant DNA response element (ARE) to activate important cellular cytoprotective defense systems. Recently several types of cancers have been shown to overexpress Nrf2, but its role in the cellular response to radiation therapy has yet to be fully determined. In this study, we report that single doses of ionizing radiation from 2-8Gy activate ARE-dependent transcription in breast cancer cells in a dose-dependent manner, but only after a delay of 5 days. Clinically relevant daily dose fractions of radiation also increased ARE-dependent transcription, but again only after 5 days. Downstream activation occurred of Nrf2-ARE-dependent gene and protein markers, such as heme oxygenase-1, whereas Nrf2-deficient fibroblasts were incapable of these responses. Compared to wild-type fibroblasts, Nrf2-deficient fibroblasts had relatively high basal levels of reactive oxygen species that increased greatly five days after radiation exposure. Further, in vitro clonogenic survival assays and in vivo sublethal whole body irradiation tests demonstrated that Nrf2 deletion increased radiation sensitivity, whereas Nrf2-inducing drugs did not increase radioresistance. Our results indicate that the Nrf2-ARE pathway is important to maintain resistance to irradiation, but that it operates as a second-tier antioxidant adaptive response system activated by radiation only under specific circumstances, including those that may be highly relevant to tumor response during standard clinical dose-fractionated radiation therapy. PMID:20940400

  11. Transonic calculation of airfoil stability and response with active controls

    NASA Technical Reports Server (NTRS)

    Batina, J. T.; Ynag, T. Y.

    1984-01-01

    Transonic aeroelastic stability and response analyses are performed for the MBB A-3 supercritical airfoil. Three degrees of freedom are considered: plunge, pitch, and aileron pitch. The control of airfoil stability and response in transonic flow are studied. Stability analyses are performed using a Pade aeroelastic model based on the use of LTRAN2-NLR transonic small disturbance finite difference computer code. Response analyses are performed by coupling the structural equations of motion to the unsteady aerodynamic forces of LTRAN2-NLR. The focus is on transonic time marching transient response solutions using modal identification to determine stability. Frequency and damping of these modes are directly compared in the complex s-plane with Pade model eigenvalues. Transonic stability and response characteristics of 2-D airfoils are discussed and comparisons are made. Application of the Pade aeroelastic model and time marching analyses to flutter suppression using active controls is demonstrated.

  12. Cyclic AMP Modulation of Axonal Regeneration Following Spinal Cord Injury

    Microsoft Academic Search

    Sari S. Hannila; Marie T. Filbin

    Central nervous system (CNS) myelin contains several proteins that contribute to regenerative failure after spinal cord injury, and elevation of intracellular cyclic adenosine monophosphate (cAMP) has proven to be one of the most effective means of overcoming myelin inhibition. In this chapter, we describe how increasing cAMP promotes axonal regeneration in the CNS and how this finding has advanced the

  13. Cyclic AMP tastes aversive, not sweet, to rats.

    PubMed

    Houpt, T A; Frankmann, S P; Berlin, R

    1996-03-01

    Electrophysiological and biochemical evidence suggests that cAMP mediates sweet taste transduction. Neural recordings from anesthetized rats and in vitro preparations demonstrate that membrane-per-meable cAMP analogues mimic the effects of sucrose and artificial sweetners. We presented solutions of sodium 8-(4-chlorophenylthio)-adenosine 3'-5'-cyclic monophosphate (8cpt-cAMP), a water-soluble, membrane-permeable cAMP analogue to freely behaving rats in short-term lickometer tests. Rats licked significantly less to 8cpt-cAMP than to sucrose or palatable saccharin solutions. Rats could taste 8cpt-cAMP solutions, however, because they licked less to 8cpt-cAMP in mixture with sucrose than to sucrose alone. Because 8cpt-cAMP decreased licking when mixed with sucrose, we conclude that the taste of 8cpt-cAMP is aversive, not sweet, to freely behaving rats. PMID:8700952

  14. Cyclic AMP tastes aversive, not sweet, to rats

    Microsoft Academic Search

    Thomas A. Houpt; Sandra P. Frankmann; Roseanne Berlin

    1996-01-01

    Electrophysiological and biochemical evidence suggests that cAMP mediates sweet taste transduction. Neural recordings from anesthetized rats and in vitro preparations demonstrate that membrane-permeable cAMP analogues mimic the effects of sucrose and artificial sweetners. We presented solutions of sodium 8-(4-chlorophenylthio)-adenosine 3?-5?-cyclic monophosphate (8cpt-cAMP), a water-soluble, membrane-permeable cAMP analogue to freely behaving rats in short-term lickometer tests. Rats licked significantly less to

  15. Hydrogen Sulfide Induces Cyclic AMP and Modulates the NMDA Receptor

    Microsoft Academic Search

    Hideo Kimura

    2000-01-01

    Hydrogen sulfide (H2S) is produced endogenously from l-cysteine in mammalian tissues, and may function as a neuromodulator in the brain as well as a tone regulator in smooth muscle. H2S is present at relatively high levels in the brain, and cystathionine ?-synthase (CBS), which is highly expressed in the hippocampus, is involved in the production of brain H2S. Physiological concentrations

  16. Ricinoleic acid stimulation of active anion secretion in colonic mucosa of the rat.

    PubMed

    Racusen, L C; Binder, H J

    1979-04-01

    Perfusion of the colon with ricinoleic acid produces fluid and electrolyte accumulation. The mechanism of these changes in water and electrolyte movement is uknown. These studies were designed to determine whether ricinoleic acid effects active ion transport across isolated rat colonic mucosa. 0.5 mM Na ricinoleate produced significant increases in potential difference (3.8 +/- 0.5 mV) and short-circuit current (Isc) (99.2 +/- 10.1 muA/cm2). The increases in Isc produced by Na ricinoleate were inhibited by both removal of bicarbonate and chloride and by the presence of theophylline. The hydroxy fatty acid also resulted in a significant decrease in net Na absorption from 4.7 +/- 0.8 to 0.1 +/- 0.7 mueq/h cm2 and reversed net Cl transport from absorption (+ 4.5 +/- 0.9) to secretion (-2.2 +/- mueq/h cm2). In parallel studies 0.5 mM Na ricinoleate increased mucosal cyclic AMP content by 58%. The concentrations of Na ricinoleate required to produce detectable and maximal increases in both Isc and cyclic AMP were the same. These results provide evidence in support of the concept that hydroxy fatty acid-induced fluid and electrolyte accumulation is driven by an active ion secretory process. PMID:220281

  17. Activation of the renin-angiotensin system, specifically in the subfornical organ is sufficient to induce fluid intake.

    PubMed

    Coble, Jeffrey P; Cassell, Martin D; Davis, Deborah R; Grobe, Justin L; Sigmund, Curt D

    2014-08-15

    Increased activity of the renin-angiotensin system within the brain elevates fluid intake, blood pressure, and resting metabolic rate. Renin and angiotensinogen are coexpressed within the same cells of the subfornical organ, and the production and action of ANG II through the ANG II type 1 receptor in the subfornical organ (SFO) are necessary for fluid intake due to increased activity of the brain renin-angiotensin system. We generated an inducible model of ANG II production by breeding transgenic mice expressing human renin in neurons controlled by the synapsin promoter with transgenic mice containing a Cre-recombinase-inducible human angiotensinogen construct. Adenoviral delivery of Cre-recombinase causes SFO-selective induction of human angiotensinogen expression. Selective production of ANG II in the SFO results in increased water intake but did not change blood pressure or resting metabolic rate. The increase in water intake was ANG II type 1 receptor-dependent. When given a choice between water and 0.15 M NaCl, these mice increased total fluid and sodium, but not water, because of an increased preference for NaCl. When provided a choice between water and 0.3 M NaCl, the mice exhibited increased fluid, water, and sodium intake, but no change in preference for NaCl. The increase in fluid intake was blocked by an inhibitor of PKC, but not ERK, and was correlated with increased phosphorylated cyclic AMP response element binding protein in the subfornical organ. Thus, increased production and action of ANG II specifically in the subfornical organ are sufficient on their own to mediate an increase in drinking through PKC. PMID:24965793

  18. Ginger improves cognitive function via NGF-induced ERK/CREB activation in the hippocampus of the mouse.

    PubMed

    Lim, Soonmin; Moon, Minho; Oh, Hyein; Kim, Hyo Geun; Kim, Sun Yeou; Oh, Myung Sook

    2014-10-01

    Ginger (the rhizome of Zingiber officinale Roscoe) has been used worldwide for many centuries in cooking and for treatment of several diseases. The main pharmacological properties of ginger include anti-inflammatory, antihyperglycemic, antiarthritic, antiemetic and neuroprotective actions. Recent studies demonstrated that ginger significantly enhances cognitive function in various cognitive disorders as well as in healthy brain. However, the biochemical mechanisms underlying the ginger-mediated enhancement of cognition have not yet been studied in normal or diseased brain. In the present study, we assessed the memory-enhancing effects of dried ginger extract (GE) in a model of scopolamine-induced memory deficits and in normal animals by performing a novel object recognition test. We found that GE administration significantly improved the ability of mice to recognize novel objects, indicating improvements in learning and memory. Furthermore, to elucidate the mechanisms of GE-mediated cognitive enhancement, we focused on nerve growth factor (NGF)-induced signaling pathways. NGF enzyme-linked immunosorbent assay analysis revealed that GE administration led to elevated NGF levels in both the mouse hippocampus and rat glioma C6 cells. GE administration also resulted in phosphorylation of extracellular-signal-regulated kinase (ERK) and cyclic AMP response element-binding protein (CREB), as revealed by Western blotting analysis. Neutralization of NGF with a specific NGF antibody inhibited GE-triggered activation of ERK and CREB in the hippocampus. Also, GE treatment significantly increased pre- and postsynaptic markers, synaptophysin and PSD-95, which are related to synapse formation in the brain. These data suggest that GE has a synaptogenic effect via NGF-induced ERK/CREB activation, resulting in memory enhancement. PMID:25049196

  19. Recognition of microorganisms and activation of the immune response

    Microsoft Academic Search

    Ruslan Medzhitov

    2007-01-01

    The mammalian immune system has innate and adaptive components, which cooperate to protect the host against microbial infections. The innate immune system consists of functionally distinct 'modules' that evolved to provide different forms of protection against pathogens. It senses pathogens through pattern-recognition receptors, which trigger the activation of antimicrobial defences and stimulate the adaptive immune response. The adaptive immune system,

  20. Educating for Political Activity: A Younger Generational Response

    ERIC Educational Resources Information Center

    Mac an Ghaill, Mairtin

    2010-01-01

    This paper is a response to Professor Chitty's "Educational Review" Guest Lecture article, "Educating for political activity". I address the three sections of his paper: a global and national-based politics of war, corporate manipulation and parliamentary scandals. This provides a basis to draw upon empirical material from a recent critical…

  1. Invited Review Dendritic cell activation and function in response

    E-print Network

    MacDonald, Andrew

    , linking innate and adaptive immunity. Their central role in the activation of nai¨ve T cells gives DC, specialised in both the initiation and polarisation of adaptive immunity (Banchereau et al., 2000; Moser a strategic position in the control of immune responses. While the mechanisms by which viral, bacterial

  2. Bacterial lifestyle shapes the regulation of stringent response activation

    PubMed Central

    Boutte, Cara C.; Crosson, Sean

    2014-01-01

    Bacteria inhabit enormously diverse niches and have a correspondingly large array of regulatory mechanisms to adapt to often inhospitable and variable environments. The stringent response allows bacteria to quickly reprogram transcription in response to changes in nutrient availability. Although the proteins controlling this response are conserved in almost all bacterial species, recent work has illuminated considerable diversity in the starvation cues and regulatory mechanisms that activate stringent signaling proteins in bacteria from different environments. In this review we describe the signals and genetic circuitries that control the stringent signaling systems of a copiotroph, a bacteriovore, an oligotroph and a mammalian pathogen – Escherichia coli, Myxococcus xanthus, Caulobacter crescentus and Mycobacterium tuberculosis, respectively – and discuss how control of the stringent response in these species is adapted to their particular lifestyles. PMID:23419217

  3. [Bone marrow stromal damage mediated by immune response activity].

    PubMed

    Vojinovi?, J; Kamenov, B; Najman, S; Brankovi?, Lj; Dimitrijevi?, H

    1994-01-01

    The aim of this work was to estimate influence of activated immune response on hematopoiesis in vitro, using the experimental model of BCG immunized BALB/c mice and in patients with chronic immunoactivation: long-lasting infections, autoimmunity or malignancy. We correlated changes in long term bone marrow cultures (Dexter) and NBT reduction with appearance of anemia in patients and experimental model of immunization by BCG. Increased spontaneous NBT reduction pointed out role of macrophage activation in bone marrow stroma damage. Long-term bone marrow cultures showed reduced number of hematopoietic cells, with predomination of fibroblasts and loss of fat cells. This results correlated with anemia and leucocytosis with stimulated myelopoiesis in peripheral blood. Activation of immune response, or acting of any agent that directly changes extracellular matrix and cellularity of bone marrow, may result in microenviroment bone marrow damage that modify hematopoiesis. PMID:18173180

  4. Delphinid behavioral responses to incidental mid-frequency active sonar.

    PubMed

    Henderson, E Elizabeth; Smith, Michael H; Gassmann, Martin; Wiggins, Sean M; Douglas, Annie B; Hildebrand, John A

    2014-10-01

    Opportunistic observations of behavioral responses by delphinids to incidental mid-frequency active (MFA) sonar were recorded in the Southern California Bight from 2004 through 2008 using visual focal follows, static hydrophones, and autonomous recorders. Sound pressure levels were calculated between 2 and 8?kHz. Surface behavioral responses were observed in 26 groups from at least three species of 46 groups out of five species encountered during MFA sonar incidents. Responses included changes in behavioral state or direction of travel, changes in vocalization rates and call intensity, or a lack of vocalizations while MFA sonar occurred. However, 46% of focal groups not exposed to sonar also changed their behavior, and 43% of focal groups exposed to sonar did not change their behavior. Mean peak sound pressure levels when a behavioral response occurred were around 122?dB re: 1??Pa. Acoustic localizations of dolphin groups exhibiting a response gave insight into nighttime movement patterns and provided evidence that impacts of sonar may be mediated by behavioral state. The lack of response in some cases may indicate a tolerance of or habituation to MFA sonar by local populations; however, the responses that occur at lower received levels may point to some sensitization as well. PMID:25324099

  5. Multiple nuclear factors interact with promoter sequences of the urokinase-type plasminogen activator gene.

    PubMed Central

    von der Ahe, D; Pearson, D; Nakagawa, J; Rajput, B; Nagamine, Y

    1988-01-01

    To characterize proteins that bind to the cyclic AMP inducible promoter of the urokinase-type plasminogen activator gene, we performed a DNAase I footprinting analysis. Within 500 nucleotides upstream of the transcription start site we found eight protected regions due to at least four different binding proteins. Among these is a single binding site for the transcription factor CTF/NF1, which is flanked on each side by two conserved binding sites for the transcription factor Sp1. A region at -380, which shares a similarity with sequences observed in the corresponding regions of other cyclic AMP regulated genes, was protected. This binding site contains a sequence of ten nucleotides which is repeated further upstream at -480 and also protected against DNAase I digestion. Comparisons of extracts from four different cell lines revealed that all DNA binding factors are present in nuclei of uPA expressing and nonexpressing cells. Mechanism underlying hormonal regulation of the gene is discussed. Images PMID:3412894

  6. Discordant biological and toxicological species responses to TLR3 activation.

    PubMed

    Mitchell, William M; Nicodemus, Christopher F; Carter, William A; Horvath, Joseph C; Strayer, David R

    2014-04-01

    Toll-like receptors (TLRs) are highly conserved type 1 membrane proteins that initiate a multiplicity of transient gene transcriptions, resulting in innate and adaptive immune responses. These essential immune responses are triggered by common TLR pattern recognition receptors of microbial products expressed through the cytoplasmic carboxy-terminal Toll/IL-1 domain. Toll/IL-1 adapter protein cascades are induced by an activated Toll/IL-1 to induce transient transcription responses. All TLRs, with the exception of TLR3, use an MyD88 adapter to Toll/IL-1 to initiate a proinflammatory cascade. TLR3 uses the toll receptor 3/4 induction factor adapter to initiate a different cytosolic adapter cascade with double-stranded RNA agonists. This non-MyD88 pathway induces both NF-?B and type 1 interferon responses. By using a TLR3-restricted double-stranded RNA agonist, rintatolimod, we demonstrate significant unexpected differences in toxic responses between rats and primates. The mechanism of this differential response is consistent with a relative down-regulation of the NF-?B inflammatory cytokine induction pathway in the cynomolgus monkey and humans, but not observed systemically in rat. Our findings suggest evaluation of TLR3 agonists in drug therapy. PMID:24486326

  7. Response Activation in Overlapping Tasks and the Response-Selection Bottleneck

    ERIC Educational Resources Information Center

    Schubert, Torsten; Fischer, Rico; Stelzel, Christine

    2008-01-01

    The authors investigated the impact of response activation on dual-task performance by presenting a subliminal prime before the stimulus in Task 2 (S2) of a psychological refractory period (PRP) task. Congruence between prime and S2 modulated the reaction times in Task 2 at short stimulus onset asynchrony despite a PRP effect. This Task 2…

  8. The relationship between the agonist-induced activation and desensitization of the human tachykinin NK2 receptor expressed in Xenopus oocytes

    PubMed Central

    Maudsley, S; Gent, J P; Findlay, J B C; Donnelly, D

    1998-01-01

    Repeated applications of neurokinin?A (NKA) to oocytes injected with 25?ng wild-type hNK2 receptor cRNA caused complete attenuation of second and subsequent NKA-induced responses while analogous experiments using repeated applications of GR64349 and [Nle10]NKA(4–10) resulted in no such desensitization. This behaviour has been previously attributed to the ability of the different ligands to stabilize different active conformations of the receptor that have differing susceptibilities to receptor kinases (Nemeth & Chollet, 1995).However, for Xenopus oocytes injected (into the nucleus) with 10?ng wild-type hNK2 receptor cDNA, a single 100?nM concentration of any of the three ligands resulted in complete desensitization to further concentrations.On the other hand, none of the ligands caused any desensitization in oocytes injected with 0.25?ng wild-type hNK2 receptor cRNA, even at concentrations up to 10??M.The two N-terminally truncated analogues of neurokinin?A have a lower efficacy than NKA and it is likely that it is this property which causes the observed differences in desensitization, rather than the formation of alternative active states of the receptor.The peak calcium-dependent chloride current is not a reliable measure of maximal receptor stimulation and efficacy is better measured in this system by studying agonist-induced desensitization.The specific adenylyl cyclase inhibitor SQ22536 can enhance NKA and GR64349-mediated desensitization which suggests that agonist-induced desensitization involves the inhibition of adenylyl cyclase and the subsequent down-regulation of the cyclic AMP-dependent protein kinase, possibly by cross-talk to a second signalling pathway. PMID:9690859

  9. Topiramate protects against glutamate excitotoxicity via activating BDNF/TrkB-dependent ERK pathway in rodent hippocampal neurons.

    PubMed

    Mao, Xiao-Yuan; Cao, Yong-Gang; Ji, Zhong; Zhou, Hong-Hao; Liu, Zhao-Qian; Sun, Hong-Li

    2015-07-01

    Topiramate (TPM) was previously found to have neuroprotection against neuronal injury in epileptic and ischemic models. However, whether TPM protects against glutamate-induced excitotoxicity in hippocampal neurons is elusive. Our present work aimed to evaluate the protective effect of TPM against glutamate toxicity in hippocampal neurons and further figure out the potential molecular mechanisms. The in vitro glutamate excitotoxic model was prepared with 125?M glutamate for 20min. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) analysis and Hoechst 33342 staining were conducted to detect neuronal survival. The protein expressions of brain-derived neurotrophic factor (BDNF), TrkB, mitogen-activated protein kinase (MAPK) cascade (including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 MAPK), cyclic AMP response element binding protein (CREB), Bcl-2, Bax and ?-actin were detected via Western blot assay. Our results demonstrated that TPM protected hippocampal neurons from glutamate toxicity. Meanwhile, the pretreatment of TPM for 10min significantly prevented the down-regulation of BDNF and the phosphorylation of TrkB. Furthermore, the elevation of phosphorylated EKR expression was significantly inhibited after blockade of TrkB by TrkB IgG, while no alterations of phosphorylated JNK and p38 MAPK were found in the cultured hippocampal neurons. Besides, it was also found that the enhanced phosphorylation of CREB was evidently reversed under excitotoxic conditions after treating with U0126 (the selective inhibitor of ERK). The protein level of Bcl-2 was also observed to be remarkably increased after TPM treatment. In conclusion, these findings implicate that TPM exerts neuroprotective effects against glutamate excitotoxicity in hippocampal neurons and its protection may be modulated through BDNF/TrkB-dependent ERK pathway. PMID:25661849

  10. Affective Response to Physical Activity: Testing for Measurement Invariance of the Physical Activity Affect Scale Across Active and Non-Active Individuals

    Microsoft Academic Search

    Laura C. Carpenter; Sara Anne Tompkins; Sarah J. Schmiege; Renea Nilsson; Angela Bryan

    2010-01-01

    Affective responses to physical activity are assumed to play a role in exercise initiation and maintenance. The Physical Activity Affect Scale measures four dimensions of an individual's affective response to exercise. Group differences in the interpretation of scale items can impact the interpretability of mean differences, underscoring the need to examine whether measurement structure holds across groups (e.g., active vs.

  11. Recognition of microorganisms and activation of the immune response.

    PubMed

    Medzhitov, Ruslan

    2007-10-18

    The mammalian immune system has innate and adaptive components, which cooperate to protect the host against microbial infections. The innate immune system consists of functionally distinct 'modules' that evolved to provide different forms of protection against pathogens. It senses pathogens through pattern-recognition receptors, which trigger the activation of antimicrobial defences and stimulate the adaptive immune response. The adaptive immune system, in turn, activates innate effector mechanisms in an antigen-specific manner. The connections between the various immune components are not fully understood, but recent progress brings us closer to an integrated view of the immune system and its function in host defence. PMID:17943118

  12. Photodynamic therapy for cancer and activation of immune response

    NASA Astrophysics Data System (ADS)

    Mroz, Pawel; Huang, Ying-Ying; Hamblin, Michael R.

    2010-02-01

    Anti-tumor immunity is stimulated after PDT for cancer due to the acute inflammatory response, exposure and presentation of tumor-specific antigens, and induction of heat-shock proteins and other danger signals. Nevertheless effective, powerful tumor-specific immune response in both animal models and also in patients treated with PDT for cancer, is the exception rather than the rule. Research in our laboratory and also in others is geared towards identifying reasons for this sub-optimal immune response and discovering ways of maximizing it. Reasons why the immune response after PDT is less than optimal include the fact that tumor-antigens are considered to be self-like and poorly immunogenic, the tumor-mediated induction of CD4+CD25+foxP3+ regulatory T-cells (T-regs), that are able to inhibit both the priming and the effector phases of the cytotoxic CD8 T-cell anti-tumor response and the defects in dendritic cell maturation, activation and antigen-presentation that may also occur. Alternatively-activated macrophages (M2) have also been implicated. Strategies to overcome these immune escape mechanisms employed by different tumors include combination regimens using PDT and immunostimulating treatments such as products obtained from pathogenic microorganisms against which mammals have evolved recognition systems such as PAMPs and toll-like receptors (TLR). This paper will cover the use of CpG oligonucleotides (a TLR9 agonist found in bacterial DNA) to reverse dendritic cell dysfunction and methods to remove the immune suppressor effects of T-regs that are under active study.

  13. Cryopyrin activates the inflammasome in response to toxins and ATP

    Microsoft Academic Search

    Sanjeev Mariathasan; David S. Weiss; Kim Newton; Jacqueline McBride; Karen O'Rourke; Meron Roose-Girma; Wyne P. Lee; Yvette Weinrauch; Denise M. Monack; Vishva M. Dixit

    2006-01-01

    A crucial part of the innate immune response is the assembly of the inflammasome, a cytosolic complex of proteins that activates caspase-1 to process the proinflammatory cytokines interleukin (IL)-1beta and IL-18. The adaptor protein ASC is essential for inflammasome function, binding directly to caspase-1 (refs 3, 4), but the triggers of this interaction are less clear. ASC also interacts with

  14. Ionosphere response to recurrent geomagnetic activity: local time dependency

    NASA Astrophysics Data System (ADS)

    Pedatella, N. M.; Lei, J.; Thayer, J. P.; Forbes, J. M.

    2009-12-01

    Observations of global positioning system total electron content (TEC) and in-situ electron densities at altitudes of ~350-370 km from the CHAMP satellite are used to illustrate the local time and latitude dependence of 9-day periodicities due to recurring high-speed solar wind streams and geomagnetic activity in the ionosphere during 2005. A local time dependence is found, with nighttime TEC oscillations concentrated at high-latitudes and close to ±40 percent of background levels. The largest oscillations in daytime TEC occur at mid-latitudes and are ±25 percent of background levels. Furthermore, the daytime response is generally symmetric about the geomagnetic equator with anti-correlation between high- and low-latitudes, whereas at night the high-latitude Northern Hemisphere is generally in-phase with low-latitudes and anti-correlated with the high-latitude Southern Hemisphere. A combination of enhanced equatorial neutral winds and changes in neutral composition are thought to be the primary mechanisms responsible for the observed ionospheric response. Although similar mechanisms are driving the response, the local time dependency arises due to the presence (lack) of photoionization during the daytime (nighttime). Similar trends are observed in CHAMP in-situ electron densities; however, the oscillations at a near constant altitude are ~10-15 percent larger than the TEC oscillations. Additionally, the CHAMP observations reveal possible variations in the strength of the equatorial ionization anomaly, indicating that disturbance dynamo electric fields may also contribute to the ionospheric response to recurrent geomagnetic activity. The results presented are the first to reveal the significant differences between the daytime and nighttime response of the ionosphere to periodic forcing from solar wind high-speed streams.

  15. Ionosphere response to recurrent geomagnetic activity: Local time dependency

    NASA Astrophysics Data System (ADS)

    Pedatella, N. M.; Lei, J.; Thayer, J. P.; Forbes, J. M.

    2010-02-01

    Observations of global positioning system total electron content (TEC) and in situ electron densities at altitudes of ˜350-370 km from the CHAMP satellite are used to illustrate the local time and latitude dependence of 9 day periodicities in the ionosphere due to recurring high-speed solar wind streams and geomagnetic activity during 2005. A local time dependence is found, with nighttime TEC oscillations concentrated at high latitudes and close to ±40% of background levels. The largest oscillations in daytime TEC occur at midlatitudes and are ±25% of background levels. Furthermore, the daytime response is generally symmetric about the geomagnetic equator with anticorrelation between high and low latitudes, whereas at night the high-latitude Northern Hemisphere is generally in-phase with low latitudes and anticorrelated with the high-latitude Southern Hemisphere. A combination of enhanced equatorward neutral winds and changes in neutral composition are thought to be the primary mechanisms responsible for the observed ionospheric response. Although similar mechanisms are driving the response, the local time dependency arises because of the presence (lack) of photoionization during the daytime (nighttime). Similar trends are observed in CHAMP in situ electron densities; however, the oscillations at a near-constant altitude are ˜10-15% larger than the TEC oscillations. Additionally, the CHAMP observations reveal possible variations in the strength of the equatorial ionization anomaly, indicating that disturbance dynamo electric fields may also contribute to the ionospheric response to recurrent geomagnetic activity. The results presented are the first to reveal the significant differences between the daytime and nighttime response of the ionosphere to periodic forcing from solar wind high-speed streams.

  16. Ionosphere response to recurrent geomagnetic activity in 1974

    NASA Astrophysics Data System (ADS)

    Fang, Tzu-Wei; Forbes, Jeffrey M.

    2012-01-01

    The 9 day variation of Earth's thermosphere neutral density in 2005 and 2006 is known to have been influenced by rotating solar coronal holes and the quasiperiodic solar wind high-speed streams (HSSs) and by the concomitant recurrent geomagnetic activity that they induce. The corresponding responses in ion temperature, ionospheric electron density, and total electron content have also been reported during the same period. In 1974, a significant 13.5 day periodicity in geomagnetic activity was created by the quasiperiodic HSS associated with two major solar coronal hole regions separated by about 180°. In the present paper, ionospheric F-region peak plasma density (NmF2) and height (hmF2) in the daytime and nighttime from 12 ionosonde stations are analyzed to delineate the responses to this epoch of HSS forcing of the geospace system. Results show that the ionospheric responses to this 13.5 day periodic forcing are similar in some ways to responses to the 9 day periodicity. For instance, in middle and high latitudes, daytime and nighttime NmF2 is mostly out of phase with the fluctuations in the daily mean Kp index (Kp¯), while the daytime hmF2 are in phase with the Kp¯ fluctuations. Empirical model results confirm the important role of thermal expansion in connecting thermospheric and ionospheric changes driven by high-speed streams and recurrent geomagnetic activity. At low latitudes, the 13.5 day signatures are not as straightforward as those at middle and high latitudes, and significant spectral energy thought to be connected with planetary waves and perhaps other lower-atmosphere influences exists at periods of less than 13.5 days.

  17. Optimization of an Active Twist Rotor Blade Planform for Improved Active Response and Forward Flight Performance

    NASA Technical Reports Server (NTRS)

    Sekula, Martin K; Wilbur, Matthew L.

    2014-01-01

    A study was conducted to identify the optimum blade tip planform for a model-scale active twist rotor. The analysis identified blade tip design traits which simultaneously reduce rotor power of an unactuated rotor while leveraging aeromechanical couplings to tailor the active response of the blade. Optimizing the blade tip planform for minimum rotor power in forward flight provided a 5 percent improvement in performance compared to a rectangular blade tip, but reduced the vibration control authority of active twist actuation by 75 percent. Optimizing for maximum blade twist response increased the vibration control authority by 50 percent compared to the rectangular blade tip, with little effect on performance. Combined response and power optimization resulted in a blade tip design which provided similar vibration control authority to the rectangular blade tip, but with a 3.4 percent improvement in rotor performance in forward flight.

  18. Substance P primes lipoteichoic acid- and Pam3CysSerLys4-mediated activation of human mast cells by up-regulating Toll-like receptor 2.

    PubMed

    Tancowny, Brian P; Karpov, Victor; Schleimer, Robert P; Kulka, Marianna

    2010-10-01

    Substance P (SP) is a neuropeptide with neuroimmunoregulatory activity that may play a role in susceptibility to infection. Human mast cells, which are important in innate immune responses, were analysed for their responses to pathogen-associated molecules via Toll-like receptors (TLRs) in the presence of SP. Human cultured mast cells (LAD2) were activated by SP and TLR ligands including lipopolysaccharide (LPS), Pam3CysSerLys4 (Pam3CSK4) and lipoteichoic acid (LTA), and mast cell leukotriene and chemokine production was assessed by enzyme-linked immunosorbent assay (ELISA) and gene expression by quantitative PCR (qPCR). Mast cell degranulation was determined using a ?-hexosaminidase (?-hex) assay. SP treatment of LAD2 up-regulated mRNA for TLR2, TLR4, TLR8 and TLR9 while anti-immunoglobulin E (IgE) stimulation up-regulated expression of TLR4 only. Flow cytometry and western blot confirmed up-regulation of TLR2 and TLR8. Pretreatment of LAD2 with SP followed by stimulation with Pam3CSK4 or LTA increased production of leukotriene C4 (LTC(4) ) and interleukin (IL)-8 compared with treatment with Pam3CSK4 or LTA alone (>2-fold; P<0·01). SP alone activated 5-lipoxygenase (5-LO) nuclear translocation but also augmented Pam3CSK4 and LTA-mediated 5-LO translocation. Pam3CSK4, LPS and LTA did not induce LAD2 degranulation. SP primed LTA and Pam3CSK4-mediated activation of JNK, p38 and extracellular-signal-regulated kinase (ERK) and activated the nuclear translocation of c-Jun, nuclear factor (NF)-?B, activating transcription factor 2 (ATF-2) and cyclic-AMP-responsive element binding protein (CREB) transcription factors. Pretreatment with SP followed by LTA stimulation synergistically induced production of chemokine (C-X-C motif) ligand 8 (CXCL8)/IL-8, chemokine (C-C motif) ligand 2 (CCL2)/monocyte chemotactic protein 1 (MCP-1), tumour necrosis factor (TNF) and IL-6 protein. SP primes TLR2-mediated activation of human mast cells by up-regulating TLR expression and potentiating signalling pathways associated with TLR. These results suggest that neuronal responses may influence innate host defence responses. PMID:20497485

  19. Activation and regulation of ATM kinase activity in response to DNA double-strand breaks.

    PubMed

    Lee, J-H; Paull, T T

    2007-12-10

    The ataxia-telangiectasia-mutated (ATM) protein kinase is rapidly and specifically activated in response to DNA double-strand breaks in eukaryotic cells. In this review, we summarize recent insights into the mechanism of ATM activation, focusing on the role of the Mre11/Rad50/Nbs1 (MRN) complex in this process. We also compare observations of the ATM activation process in different biological systems and highlight potential candidates for cellular factors that may participate in regulating ATM activity in human cells. PMID:18066086

  20. 77 FR 20887 - Proposed Information Collection (National Acquisition Center Customer Response Survey) Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-06

    ...National Acquisition Center Customer Response Survey) Activity...information needed to measure customer satisfaction with delivered products and services...National Acquisition Center Customer Response Survey, VA Form...

  1. Immunomodulatory activity of andrographolide on macrophage activation and specific antibody response

    Microsoft Academic Search

    Wei Wang; Jing Wang; Sheng-fu Dong; Chun-hong Liu; Paola Italiani; Shu-hui Sun; Jing Xu; Diana Boraschi; Shi-ping Ma; Di Qu

    2010-01-01

    Aim:To investigate the immunomodulatory effects of andrographolide on both innate and adaptive immune responses.Methods:Andrographolide (10 ?g\\/mL in vitro or 1 mg\\/kg in vivo) was used to modulate LPS-induced classical activated (M1) or IL-4-induced alternative activated (M2) macrophages in vitro and humor immune response to HBsAg in vivo. Cytokine gene expression profile (M1 vs M2) was measured by real-time PCR, IL-12\\/IL-10

  2. Physiologic Responses Produced by Active and Passive Personal Cooling Vests

    NASA Technical Reports Server (NTRS)

    Ku, Yu-Tsuan E.; Lee, Hank C.; Montgomery, Leslie D.; Luna, Bernadette

    2000-01-01

    Personal thermoregulatory systems which provide chest cooling are used in the industrial and aerospace environments to alleviate thermal stress. However, little information is available regarding the physiologic and circulatory changes produced by routine operation of these systems. The objectives of this study were to document and compare the subjects' response to three cooling vests in their recommended configurations. The Life Enhancement Tech (LET) lightweight active cooling vest with cap, the MicroClimate Systems Change of Phase garment (MCS), and the Steele Vest were each used to cool the chest regions of 12 male and 8 female Healthy subjects (21 to 69 yr.) in this study. The subjects, seated in an upright position at normal room temperature (approx. 22 C), were tested for 60 min. with one of the cooling garments. The LET active garment had an initial coolant fluid inlet temperature of 60 F, and was ramped down to 50 F. Oral, right and left ear canal temperatures were logged manually every 5 min. Arm, leg, chest and rectal temperatures; heart rate; and respiration were recorded continuously on a U.F.I., Inc. Biolog ambulatory monitor. For men, all three vests had similar, significant cooling effects. Decreases in the average rectal temperature, oral temperature, and ear canal temperatures were approximately 0.2 C, 0.2 C and 0.1 C, respectively. In contrast to the men, the female subjects wearing the MCS and Steel vests had similar cooling responses in which the core temperature remained elevated and oral and ear canal temperatures did not drop. The LET active garment cooled most of the female subjects in this study; rectal, oral and ear temperature decreased about 0.2 C, 0.3 C and 0.3 C, respectively. These results show that the garment configurations tested do not elicit a similar thermal response in all subjects. A gender difference is evident. The LET active garment configuration was most effective in decreasing temperatures of the female subjects; the MCS vest was least effective. For male subjects, the three vests appear to be more nearly equivalent. The active garment system under study included a cooling cap, which may account for some of the difference in response.

  3. Behavioral responses of north American Elk to recreational activity

    USGS Publications Warehouse

    Naylor, L.M.; Wisdom, M.J.; Anthony, R.G.

    2009-01-01

    Off-road recreation on public lands in North America has increased dramatically in recent years. Wild ungulates are sensitive to human activities, but the effect of off-road recreation, both motorized and nonmotorized, is poorly understood. We measured responses of elk (Cervus elaphus) to recreational disturbance in northeast Oregon, USA, from April to October, 2003 and 2004. We subjected elk to 4 types of recreational disturbance: all-terrain vehicle (ATV) riding, mountain biking, hiking, and horseback riding. Motion sensors inside radiocollars worn by 13 female elk recorded resting, feeding, and travel activities at 5-minute intervals throughout disturbance and control periods. Elk fed and rested during control periods, with little time spent traveling. Travel time increased in response to all 4 disturbances and was highest in mornings. Elk travel time was highest during ATV exposure, followed by exposure to mountain biking, hiking, and horseback riding. Feeding time decreased during ATV exposure and resting decreased when we subjected elk to mountain biking and hiking disturbance in 2003. Our results demonstrated that activities of elk can be substantially affected by off-road recreation. Mitigating these effects may be appropriate where elk are a management priority. Balancing management of species like elk with off-road recreation will become increasingly important as off-road recreational uses continue to increase on public lands in North America.

  4. Organization and regulation of the D-xylose operons in Escherichia coli K-12: XylR acts as a transcriptional activator.

    PubMed Central

    Song, S; Park, C

    1997-01-01

    The metabolism of D-xylose in Escherichia coli K-12 is known to be mediated by the xylAB gene. However, the nearby xylFGHR genes were found by genome sequencing and predicted to be responsible for transport and regulation for xylose based on their sequence similarities to other functionally related genes. Here, we investigated transcriptional organization and functions of the xyl genes. An analysis with random transposon insertions revealed that the xyl genes are organized into two major transcriptional units, xylAB and xylFGHR, governed by the promoters PA and PF, respectively. However, there is an additional weak promoter, PR, which is specific for xylR. Sites of transcription initiation were determined by primer extension analysis. When studied with operon fusions to lacZ, the PA and PF promoters were activated by D-xylose and repressed by glucose. In contrast, the PR promoter was not regulated by these sugars. A mutation in xylR completely abolished expression from the PA and PF promoters, causing a defect in both growth and transport. Binding of XylR to the xyl promoter was enhanced by the presence of D-xylose, suggesting that transcription was positively regulated by XylR. In vivo footprinting analysis revealed that XylR binds to at least two DNA regions, IA and IF, each with a direct repeat. It is very likely that XylR interacts with IA and IF as a dimer. The presumed binding sites are located just upstream of the promoter consensus sequences (-35), while IA is additionally flanked by a cyclic AMP receptor protein-binding site on the other side. The proposed structure of xyl promoters is consistent with the regulation of xyl gene expression and with phenotypes of transposon insertions obtained in the promoter regions. PMID:9371449

  5. Nimodipine activates TrkB neurotrophin receptors and induces neuroplastic and neuroprotective signaling events in the mouse hippocampus and prefrontal cortex.

    PubMed

    Koskimäki, Janne; Matsui, Nobuaki; Umemori, Juzoh; Rantamäki, Tomi; Castrén, Eero

    2015-03-01

    The L-type calcium channel blocker nimodipine improves clinical outcome produced by delayed cortical ischemia or vasospasm associated with subarachnoid hemorrhage. While vasoactive mechanisms are strongly implicated in these therapeutic actions of nimodipine, we sought to test whether nimodipine might also regulate neurotrophic and neuroplastic signaling events associated with TrkB neurotrophin receptor activation. Adult male mice were acutely treated with vehicle or nimodipine (10 mg/kg, s.c., 1.5 h) after which the phosphorylation states of TrkB, cyclic-AMP response element binding protein (CREB), protein kinase B (Akt), extracellular regulated kinase (ERK), mammalian target of rapamycin (mTor) and p70S6 kinase (p70S6k) from prefrontal cortex and hippocampus were assessed. Nimodipine increased the phosphorylation of the TrkB catalytic domain and the phosphoslipase-C?1 (PLC?1) domain, whereas phosphorylation of the TrkB Shc binding site remained unaltered. Nimodipine-induced TrkB phosphorylation was associated with increased phosphorylation levels of Akt and CREB in the prefrontal cortex and the hippocampus whereas phosphorylation of ERK, mTor and p70S6k remained unaltered. Nimodipine-induced TrkB signaling was not associated with changes in BDNF mRNA or protein levels. These nimodipine-induced changes on TrkB signaling mimic those produced by antidepressant drugs and thus propose common mechanisms and long-term functional consequences for the effects of these medications. This work provides a strong basis for investigating the role of TrkB-associated signaling underlying the neuroprotective and neuroplastic effects of nimodipine in translationally relevant animal models of brain trauma or compromised synaptic plasticity. PMID:25204460

  6. Identification of Cyclic GMP-Activated Nonselective Ca2+-Permeable Cation Channels and Associated CNGC5 and CNGC6 Genes in Arabidopsis Guard Cells1[W][OPEN

    PubMed Central

    Wang, Yong-Fei; Munemasa, Shintaro; Nishimura, Noriyuki; Ren, Hui-Min; Robert, Nadia; Han, Michelle; Puzõrjova, Irina; Kollist, Hannes; Lee, Stephen; Mori, Izumi; Schroeder, Julian I.

    2013-01-01

    Cytosolic Ca2+ in guard cells plays an important role in stomatal movement responses to environmental stimuli. These cytosolic Ca2+ increases result from Ca2+ influx through Ca2+-permeable channels in the plasma membrane and Ca2+ release from intracellular organelles in guard cells. However, the genes encoding defined plasma membrane Ca2+-permeable channel activity remain unknown in guard cells and, with some exceptions, largely unknown in higher plant cells. Here, we report the identification of two Arabidopsis (Arabidopsis thaliana) cation channel genes, CNGC5 and CNGC6, that are highly expressed in guard cells. Cytosolic application of cyclic GMP (cGMP) and extracellularly applied membrane-permeable 8-Bromoguanosine 3?,5?-cyclic monophosphate-cGMP both activated hyperpolarization-induced inward-conducting currents in wild-type guard cells using Mg2+ as the main charge carrier. The cGMP-activated currents were strongly blocked by lanthanum and gadolinium and also conducted Ba2+, Ca2+, and Na+ ions. cngc5 cngc6 double mutant guard cells exhibited dramatically impaired cGMP-activated currents. In contrast, mutations in CNGC1, CNGC2, and CNGC20 did not disrupt these cGMP-activated currents. The yellow fluorescent protein-CNGC5 and yellow fluorescent protein-CNGC6 proteins localize in the cell periphery. Cyclic AMP activated modest inward currents in both wild-type and cngc5cngc6 mutant guard cells. Moreover, cngc5 cngc6 double mutant guard cells exhibited functional abscisic acid (ABA)-activated hyperpolarization-dependent Ca2+-permeable cation channel currents, intact ABA-induced stomatal closing responses, and whole-plant stomatal conductance responses to darkness and changes in CO2 concentration. Furthermore, cGMP-activated currents remained intact in the growth controlled by abscisic acid2 and abscisic acid insensitive1 mutants. This research demonstrates that the CNGC5 and CNGC6 genes encode unique cGMP-activated nonselective Ca2+-permeable cation channels in the plasma membrane of Arabidopsis guard cells. PMID:24019428

  7. Identification of cyclic GMP-activated nonselective Ca2+-permeable cation channels and associated CNGC5 and CNGC6 genes in Arabidopsis guard cells.

    PubMed

    Wang, Yong-Fei; Munemasa, Shintaro; Nishimura, Noriyuki; Ren, Hui-Min; Robert, Nadia; Han, Michelle; Puzõrjova, Irina; Kollist, Hannes; Lee, Stephen; Mori, Izumi; Schroeder, Julian I

    2013-10-01

    Cytosolic Ca(2+) in guard cells plays an important role in stomatal movement responses to environmental stimuli. These cytosolic Ca(2+) increases result from Ca(2+) influx through Ca(2+)-permeable channels in the plasma membrane and Ca(2+) release from intracellular organelles in guard cells. However, the genes encoding defined plasma membrane Ca(2+)-permeable channel activity remain unknown in guard cells and, with some exceptions, largely unknown in higher plant cells. Here, we report the identification of two Arabidopsis (Arabidopsis thaliana) cation channel genes, CNGC5 and CNGC6, that are highly expressed in guard cells. Cytosolic application of cyclic GMP (cGMP) and extracellularly applied membrane-permeable 8-Bromoguanosine 3',5'-cyclic monophosphate-cGMP both activated hyperpolarization-induced inward-conducting currents in wild-type guard cells using Mg(2+) as the main charge carrier. The cGMP-activated currents were strongly blocked by lanthanum and gadolinium and also conducted Ba(2+), Ca(2+), and Na(+) ions. cngc5 cngc6 double mutant guard cells exhibited dramatically impaired cGMP-activated currents. In contrast, mutations in CNGC1, CNGC2, and CNGC20 did not disrupt these cGMP-activated currents. The yellow fluorescent protein-CNGC5 and yellow fluorescent protein-CNGC6 proteins localize in the cell periphery. Cyclic AMP activated modest inward currents in both wild-type and cngc5cngc6 mutant guard cells. Moreover, cngc5 cngc6 double mutant guard cells exhibited functional abscisic acid (ABA)-activated hyperpolarization-dependent Ca(2+)-permeable cation channel currents, intact ABA-induced stomatal closing responses, and whole-plant stomatal conductance responses to darkness and changes in CO2 concentration. Furthermore, cGMP-activated currents remained intact in the growth controlled by abscisic acid2 and abscisic acid insensitive1 mutants. This research demonstrates that the CNGC5 and CNGC6 genes encode unique cGMP-activated nonselective Ca(2+)-permeable cation channels in the plasma membrane of Arabidopsis guard cells. PMID:24019428

  8. Amarogentin, a Secoiridoid Glycoside, Abrogates Platelet Activation through PLC?2-PKC and MAPK Pathways

    PubMed Central

    Yen, Ting-Lin; Lu, Wan-Jung; Lien, Li-Ming; Thomas, Philip Aloysius; Lee, Tzu-Yin; Chiu, Hou-Chang; Sheu, Joen-Rong

    2014-01-01

    Amarogentin, an active principle of Gentiana lutea, possess antitumorigenic, antidiabetic, and antioxidative properties. Activation of platelets is associated with intravascular thrombosis and cardiovascular diseases. The present study examined the effects of amarogentin on platelet activation. Amarogentin treatment (15~60??M) inhibited platelet aggregation induced by collagen, but not thrombin, arachidonic acid, and U46619. Amarogentin inhibited collagen-induced phosphorylation of phospholipase C (PLC)?2, protein kinase C (PKC), and mitogen-activated protein kinases (MAPKs). It also inhibits in vivo thrombus formation in mice. In addition, neither the guanylate cyclase inhibitor ODQ nor the adenylate cyclase inhibitor SQ22536 affected the amarogentin-mediated inhibition of platelet aggregation, which suggests that amarogentin does not regulate the levels of cyclic AMP and cyclic GMP. In conclusion, amarogentin prevents platelet activation through the inhibition of PLC?2-PKC cascade and MAPK pathway. Our findings suggest that amarogentin may offer therapeutic potential for preventing or treating thromboembolic disorders. PMID:24868545

  9. Active microwave responses - An aid in improved crop classification

    NASA Technical Reports Server (NTRS)

    Rosenthal, W. D.; Blanchard, B. J.

    1984-01-01

    A study determined the feasibility of using visible, infrared, and active microwave data to classify agricultural crops such as corn, sorghum, alfalfa, wheat stubble, millet, shortgrass pasture and bare soil. Visible through microwave data were collected by instruments on board the NASA C-130 aircraft over 40 agricultural fields near Guymon, OK in 1978 and Dalhart, TX in 1980. Results from stepwise and discriminant analysis techniques indicated 4.75 GHz, 1.6 GHz, and 0.4 GHz cross-polarized microwave frequencies were the microwave frequencies most sensitive to crop type differences. Inclusion of microwave data in visible and infrared classification models improved classification accuracy from 73 percent to 92 percent. Despite the results, further studies are needed during different growth stages to validate the visible, infrared, and active microwave responses to vegetation.

  10. 77 FR 38398 - Agency Information Collection (National Acquisition Center Customer Response Survey) Activities...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-27

    ...National Acquisition Center Customer Response Survey) Activities Under OMB Review...National Acquisition Center Customer Response Survey, VA Form 0863. OMB Control Number...Respondent: 5 minutes. Frequency of Response: On occasion. Estimated...

  11. 75 FR 21648 - MMS Information Collection Activity: 1010-0106, Oil Spill Financial Responsibility for Offshore...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-26

    ...Collection Activity: 1010-0106, Oil Spill Financial Responsibility for Offshore...regulations under ``30 CFR Part 253, Oil Spill Financial Responsibility for Offshore...INFORMATION: Title: 30 CFR Part 253, Oil Spill Financial Responsibility for...

  12. 77 FR 60715 - Information Collection Activities: Oil-Spill Response Requirements for Facilities Located Seaward...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-04

    ...Information Collection Activities: Oil-Spill Response Requirements for Facilities...regulations under 30 CFR Part 254, ``Oil-Spill Response Requirements for Facilities...INFORMATION: Title: 30 CFR 254, Oil-Spill Response Requirements for...

  13. 77 FR 33479 - Information Collection Activities: Oil-Spill Response Requirements for Facilities Located Seaward...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-06

    ...Information Collection Activities: Oil-Spill Response Requirements for Facilities...regulations under Part 254, ``Oil-Spill Response Requirements for Facilities...INFORMATION: Title: 30 CFR 254, Oil-Spill Response Requirements for...

  14. 75 FR 54354 - BOEMRE Information Collection Activity: 1010-0106, Oil Spill Financial Responsibility for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-07

    ...Collection Activity: 1010-0106, Oil Spill Financial Responsibility for Offshore...regulations under 30 CFR part 253, ``Oil Spill Financial Responsibility for Offshore...INFORMATION: Title: 30 CFR 253, Oil Spill Financial Responsibility for...

  15. Activation of Innate Immune Responses by Haemophilus influenzae Lipooligosaccharide

    PubMed Central

    Choi, Joshua; Cox, Andrew D.; Li, Jianjun; McCready, William

    2014-01-01

    A Gram-negative pathogen Haemophilus influenzae has a truncated endotoxin known as lipooligosaccharide (LOS). Recent studies on H. influenzae LOS highlighted its structural and compositional implications for bacterial virulence; however, the role of LOS in the activation of innate and adaptive immunity is poorly understood. THP-1 monocytes were stimulated with either lipopolysaccharide (LPS) from Escherichia coli or LOS compounds derived from H. influenzae Eagan, Rd, and Rd lic1 lpsA strains. Cell surface expression of key antigen-presenting, costimulatory, and adhesion molecules, as well as gene expression of some cytokines and pattern recognition receptors, were studied. Eagan and Rd LOS had a lower capacity to induce the expression of ICAM-1, CD40, CD58, tumor necrosis factor alpha (TNF-?), and interleukin-1? (IL-1?) compared to LPS. In contrast, antigen-presenting (HLA-ABC or HLA-DR) and costimulatory (CD86) molecules and NOD2 were similarly upregulated in response to LOS and LPS. LOS from a mutant Rd strain (Rd lic1 lpsA) consistently induced higher expression of innate immune molecules than the wild-type LOS, suggesting the importance of phosphorylcholine and/or oligosaccharide extension in cellular responses to LOS. An LOS compound with a strong ability to upregulate antigen-presenting and costimulatory molecules combined with a low proinflammatory activity may be considered a vaccine candidate to immunize against H. influenzae. PMID:24671554

  16. Tirasemtiv amplifies skeletal muscle response to nerve activation in humans

    PubMed Central

    Hansen, Richard; Saikali, Khalil G; Chou, Willis; Russell, Alan J; Chen, Michael M; Vijayakumar, Vipin; Stoltz, Randall R; Baudry, Stephane; Enoka, Roger M; Morgans, David J; Wolff, Andrew A; Malik, Fady I

    2014-01-01

    Introduction: In this study we tested the hypothesis that tirasemtiv, a selective fast skeletal muscle troponin activator that sensitizes the sarcomere to calcium, could amplify the response of muscle to neuromuscular input in humans. Methods: Healthy men received tirasemtiv and placebo in a randomized, double-blind, 4-period, crossover design. The deep fibular nerve was stimulated transcutaneously to activate the tibialis anterior muscle and produce dorsiflexion of the foot. The force–frequency relationship of tibialis anterior dorsiflexion was assessed after dosing. Results: Tirasemtiv increased force produced by the tibialis anterior in a dose-, concentration-, and frequency-dependent manner with the largest increases [up to 24.5% (SE 3.1), P?response of skeletal muscle to nerve input in humans. This outcome provides support for further studies of tirasemtiv as a potential therapy in conditions marked by diminished neuromuscular input. Muscle Nerve 50: 925–931, 2014 PMID:24634285

  17. Listening as a Perceived and Interactive Activity: Understanding the Impact of Verbal Listening Responses

    ERIC Educational Resources Information Center

    Hall, Bradford

    2012-01-01

    This sequenced activity encourages active engagement with the idea that listening and speaking are not inherently separate or one-way activities. Listening involves both verbal, and nonverbal responses and perceptions of effective listening are tied to these patterns of response. These patterns of response impact both the immediate communication…

  18. Enantioselective Response of Rice and Barnyard Millet on Root Growth Inhibition by Optically Active ?-Methylbenzyl Phenylureas

    Microsoft Academic Search

    Hiroyoshi Omokawa; Jae Hwan Ryoo

    2001-01-01

    Optical active ?-methylbenzyl p-tolylureas (7, 8) show diverse plant physiological properties. Experiments were conducted to evaluate the response of the optically active ?-methylbenzyl phenylureas on root growth inhibition against rice and barnyard millet and to assess differential chiral responses of both plants from the viewpoints of activity, enantioselectivity, and cross intergenus response. A preference configuration to inhibit the root growth

  19. Sulforaphane prevents pulmonary damage in response to inhaled arsenic by activating the Nrf2-defense response

    SciTech Connect

    Zheng, Yi [Department of Environmental and Occupational Health, School of Public Health, China Medical University, Shenyang, Liaoning 110001 (China) [Department of Environmental and Occupational Health, School of Public Health, China Medical University, Shenyang, Liaoning 110001 (China); Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, AZ 85721 (United States); Tao, Shasha [Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, AZ 85721 (United States)] [Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, AZ 85721 (United States); Lian, Fangru [Department of Pathology, University of Arizona, 1501 North Campbell Ave, Tucson, AZ 85724 (United States)] [Department of Pathology, University of Arizona, 1501 North Campbell Ave, Tucson, AZ 85724 (United States); Chau, Binh T. [Department of Cellular and Molecular Medicine, The University of Arizona, 1501 North Campbell Ave, Tucson, AZ 85724 (United States)] [Department of Cellular and Molecular Medicine, The University of Arizona, 1501 North Campbell Ave, Tucson, AZ 85724 (United States); Chen, Jie; Sun, Guifan [Department of Environmental and Occupational Health, School of Public Health, China Medical University, Shenyang, Liaoning 110001 (China)] [Department of Environmental and Occupational Health, School of Public Health, China Medical University, Shenyang, Liaoning 110001 (China); Fang, Deyu [Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611 (United States)] [Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611 (United States); Lantz, R. Clark [Department of Cellular and Molecular Medicine, The University of Arizona, 1501 North Campbell Ave, Tucson, AZ 85724 (United States) [Department of Cellular and Molecular Medicine, The University of Arizona, 1501 North Campbell Ave, Tucson, AZ 85724 (United States); Arizona Cancer Center, University of Arizona, 1515 North Campbell Avenue, Tucson, AZ 85724 (United States); Zhang, Donna D., E-mail: dzhang@pharmacy.arizona.edu [Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, AZ 85721 (United States); Arizona Cancer Center, University of Arizona, 1515 North Campbell Avenue, Tucson, AZ 85724 (United States)

    2012-12-15

    Exposure to arsenic is associated with an increased risk of lung disease. Novel strategies are needed to reduce the adverse health effects associated with arsenic exposure in the lung. Nrf2, a transcription factor that mediates an adaptive cellular defense response, is effective in detoxifying environmental insults and prevents a broad spectrum of diseases induced by environmental exposure to harmful substances. In this report, we tested whether Nrf2 activation protects mice from arsenic-induced toxicity. We used an in vivo arsenic inhalation model that is highly relevant to low environmental human exposure to arsenic-containing dusts. Two-week exposure to arsenic-containing dust resulted in pathological alterations, oxidative DNA damage, and mild apoptotic cell death in the lung; all of which were blocked by sulforaphane (SF) in an Nrf2-dependent manner. Mechanistically, SF-mediated activation of Nrf2 alleviated inflammatory responses by modulating cytokine production. This study provides strong evidence that dietary intervention targeting Nrf2 activation is a feasible approach to reduce adverse health effects associated with arsenic exposure. -- Highlights: ? Exposed to arsenic particles and/or SF have elevated Nrf2 and its target genes. ? Sulforaphane prevents pathological alterations, oxidative damage and cell death. ? Sulforaphane alleviates infiltration of inflammatory cells into the lungs. ? Sulforaphane suppresses arsenic-induced proinflammatory cytokine production.

  20. Xenoestrogens are potent activators of nongenomic estrogenic responses.

    PubMed

    Watson, Cheryl S; Bulayeva, Nataliya N; Wozniak, Ann L; Alyea, Rebecca A

    2007-02-01

    Studies of the nuclear transcriptional regulatory activities of non-physiological estrogens have not explained their actions in mediating endocrine disruption in animals and humans at the low concentrations widespread in the environment. However, xenoestrogens have rarely been tested for their ability to participate in the plethora of nongenomic steroid signaling pathways elucidated over the last several years. Here we review what is known about such responses in comparison to our recent evidence that xenoestrogens can rapidly and potently elicit signaling through nongenomic pathways culminating in functional endpoints. Both estradiol (E(2)) and compounds representing various classes of xenoestrogens (diethylstilbestrol, coumestrol, bisphenol A, DDE, nonylphenol, endosulfan, and dieldrin) act via a membrane version of the estrogen receptor-alpha on pituitary cells, and can provoke Ca(2+) influx via L-type channels, leading to prolactin (PRL) secretion. These hormones and mimetics can also cause the oscillating activation of extracellular regulated kinases (ERKs). However, individual estrogen mimetics differ in their potency and temporal phasing of these activations compared to each other and to E(2). It is perhaps in these ways that they disrupt some endocrine functions when acting in combination with physiological estrogens. Our quantitative assays allow comparison of these outcomes for each mimetic, and let us build a detailed picture of alternative signaling pathway usage. Such an understanding should allow us to determine the estrogenic or antiestrogenic potential of different types of xenoestrogens, and help us to develop strategies for preventing xenoestrogenic disruption of estrogen action in many tissues. PMID:17174995

  1. Exercise intensity-dependent regulation of peroxisome proliferator-activated receptor coactivator-1 mRNA abundance is associated with differential activation of upstream signalling kinases in human skeletal muscle.

    PubMed

    Egan, Brendan; Carson, Brian P; Garcia-Roves, Pablo M; Chibalin, Alexander V; Sarsfield, Fiona M; Barron, Niall; McCaffrey, Noel; Moyna, Niall M; Zierath, Juleen R; O'Gorman, Donal J

    2010-05-15

    Skeletal muscle contraction increases intracellular ATP turnover, calcium flux, and mechanical stress, initiating signal transduction pathways that modulate peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha)-dependent transcriptional programmes. The purpose of this study was to determine if the intensity of exercise regulates PGC-1alpha expression in human skeletal muscle, coincident with activation of signalling cascades known to regulate PGC-1alpha transcription. Eight sedentary males expended 400 kcal (1674 kj) during a single bout of cycle ergometer exercise on two separate occasions at either 40% (LO) or 80% (HI) of . Skeletal muscle biopsies from the m. vastus lateralis were taken at rest and at +0, +3 and +19 h after exercise. Energy expenditure during exercise was similar between trials, but the high intensity bout was shorter in duration (LO, 69.9 +/- 4.0 min; HI, 36.0 +/- 2.2 min, P < 0.05) and had a higher rate of glycogen utilization (P < 0.05). PGC-1alpha mRNA abundance increased in an intensity-dependent manner +3 h after exercise (LO, 3.8-fold; HI, 10.2-fold, P < 0.05). AMP-activated protein kinase (AMPK) (2.8-fold, P < 0.05) and calcium/calmodulin-dependent protein kinase II (CaMKII) phosphorylation (84%, P < 0.05) increased immediately after HI but not LO. p38 mitogen-activated protein kinase (MAPK) phosphorylation increased after both trials (2.0-fold, P < 0.05), but phosphorylation of the downstream transcription factor, activating transcription factor-2 (ATF-2), increased only after HI (2.4-fold, P < 0.05). Cyclic-AMP response element binding protein (CREB) phosphorylation was elevated at +3 h after both trials (80%, P < 0.05) and class IIa histone deacetylase (HDAC) phosphorylation increased only after HI (2.0-fold, P < 0.05). In conclusion, exercise intensity regulates PGC-1alpha mRNA abundance in human skeletal muscle in response to a single bout of exercise. This effect is mediated by differential activation of multiple signalling pathways, with ATF-2 and HDAC phosphorylation proposed as key intensity-dependent mediators. PMID:20308248

  2. Probing the nonlinear response of soft materials by active microrheology

    NASA Astrophysics Data System (ADS)

    Squires, Todd

    2007-03-01

    In passive microrheology, the linear viscoelastic properties of complex fluids are inferred from the Brownian motion of colloidal tracer particles. Active (but gentle) forcing may also be used to obtain such linear-response information. More significant forcing may drive the material significantly out of equilibrium, thus potentially providing a window into the nonlinear response properties of the material. In leaving the linear-response regime, however, the theoretical underpinning for passive microrheology is lost, and a variety of issues arise. Most generally, what exactly can be measured, and how can such measurements be interpreted? Using a model system (a large colloidal probe pulled through a dilute suspension of small bath particles), we examine the different sources of stress upon the probe particle (e.g. direct probe-bath collisions vs. microstructural deformations within the bulk suspension) and discuss their analog in the corresponding macro- rheological measurement (or lack thereof). Several crucial issues emerge for the interpretation of nonlinear microrheology: 1) how to interpret the inhomogeneous and non-viscometric nature of the deformation field around the probe, 2) the distinction between of direct and bulk stresses and their deconvolution, and 3) the (Lagrangian) time-dependent nature of the stress histories experienced by material elements as they advect past the probe. Having identified these issues, we discuss several adaptations of the basic technique/interpretation, both to more faithfully recover bulk rheology as well as to measure properties inaccessible to macro- rheology. While we specifically discuss a model colloidal suspension, we ultimately envision a technique capable of measuring the nonlinear rheology of general materials.

  3. Active Disaster Response System for a Smart Building

    PubMed Central

    Lin, Chun-Yen; Chu, Edward T.-H; Ku, Lun-Wei; Liu, Jane W. S.

    2014-01-01

    Disaster warning and surveillance systems have been widely applied to help the public be aware of an emergency. However, existing warning systems are unable to cooperate with household appliances or embedded controllers; that is, they cannot provide enough time for preparedness and evacuation, especially for disasters like earthquakes. In addition, the existing warning and surveillance systems are not responsible for collecting sufficient information inside a building for relief workers to conduct a proper rescue action after a disaster happens. In this paper, we describe the design and implementation of a proof of concept prototype, named the active disaster response system (ADRS), which automatically performs emergency tasks when an earthquake happens. ADRS can interpret Common Alerting Protocol (CAP) messages, published by an official agency, and actuate embedded controllers to perform emergency tasks to respond to the alerts. Examples of emergency tasks include opening doors and windows and cutting off power lines and gas valves. In addition, ADRS can maintain a temporary network by utilizing the embedded controllers; hence, victims trapped inside a building are still able to post emergency messages if the original network is disconnected. We conducted a field trial to evaluate the effectiveness of ADRS after an earthquake happened. Our results show that compared to manually operating emergency tasks, ADRS can reduce the operation time by up to 15 s, which is long enough for people to get under sturdy furniture, or to evacuate from the third floor to the first floor, or to run more than 100 m. PMID:25237897

  4. Stress responses in flavivirus-infected cells: activation of unfolded protein response and autophagy

    PubMed Central

    Blázquez, Ana-Belén; Escribano-Romero, Estela; Merino-Ramos, Teresa; Saiz, Juan-Carlos; Martín-Acebes, Miguel A.

    2014-01-01

    The Flavivirus is a genus of RNA viruses that includes multiple long known human, animal, and zoonotic pathogens such as Dengue virus, yellow fever virus, West Nile virus, or Japanese encephalitis virus, as well as other less known viruses that represent potential threats for human and animal health such as Usutu or Zika viruses. Flavivirus replication is based on endoplasmic reticulum-derived structures. Membrane remodeling and accumulation of viral factors induce endoplasmic reticulum stress that results in activation of a cellular signaling response termed unfolded protein response (UPR), which can be modulated by the viruses for their own benefit. Concomitant with the activation of the UPR, an upregulation of the autophagic pathway in cells infected with different flaviviruses has also been described. This review addresses the current knowledge of the relationship between endoplasmic reticulum stress, UPR, and autophagy in flavivirus-infected cells and the growing evidences for an involvement of these cellular pathways in the replication and pathogenesis of these viruses. PMID:24917859

  5. Involvement of Ca2+ in the inhibition by crocetin of platelet activity and thrombosis formation.

    PubMed

    Yang, Lina; Qian, Zhiyu; Yang, Yun; Sheng, Liang; Ji, Hui; Zhou, Chenghua; Kazi, Hamid Ali

    2008-10-22

    Crocetin, a unique carotenoid with potent antioxidative and anti-inflammatory activities, is a major ingredient of saffron used as an important spice and food colorant in various parts of the world. In the present study, the effects of crocetin on platelet activity and thrombosis formation were systematically investigated. Crocetin showed a dose-dependent inhibition of platelet aggregation induced by ADP, collagen, but not by arachidonic acid (AA). Crocetin significantly attenuated dense granule release, while neither platelets adhesion to collagen nor cyclic AMP level was altered by crocetin. Pretreatment with crocetin was confirmed to partially inhibit Ca (2+) mobilization via reducing both intracellular Ca (2+) release and extracellular Ca (2+) influx. Besides that, crocetin prolonged the occlusive time in electrical stimulation-induced carotid arterial thrombosis. These findings suggest that the favorable impacts of crocetin on platelet activity and thrombosis formation may be related to the inhibition of Ca (2+) elevation in stimulated platelets. PMID:18817408

  6. Active muscle response using feedback control of a finite element human arm model

    Microsoft Academic Search

    Jonas Östh; Karin Brolin; Riender Happee

    2012-01-01

    Mathematical human body models (HBMs) are important research tools that are used to study the human response in car crash situations. Development of automotive safety systems requires the implementation of active muscle response in HBM, as novel safety systems also interact with vehicle occupants in the pre-crash phase. In this study, active muscle response was implemented using feedback control of

  7. Active muscle response using feedback control of a finite element human arm model

    Microsoft Academic Search

    Jonas Östh; Karin Brolin; Riender Happee

    2011-01-01

    Mathematical human body models (HBMs) are important research tools that are used to study the human response in car crash situations. Development of automotive safety systems requires the implementation of active muscle response in HBM, as novel safety systems also interact with vehicle occupants in the pre-crash phase. In this study, active muscle response was implemented using feedback control of

  8. Induction of ornithine decarboxylase activity by growth and differentiation factors in FRTL-5 cells.

    PubMed Central

    Eggo, M. C.; Higgins, B. P.; Tam, D.; Bachrach, L. K.; Burrow, G. N.

    1989-01-01

    Induction of ornithine decarboxylase has been correlated with the onset of cellular proliferation and cAMP production. Whether the resulting increases in polyamine levels are essential mediators of growth and/or differentiation or are merely incidental remains controversial. We have used FRTL-5 thyroid cells in culture to study the effects of three growth factors on ornithine decarboxylase activity. These factors [TSH, bovine calf serum, and 12-O-tetradecanoylphorbol-13-acetate (TPA)] are thought to act through different intracellular pathways. TSH stimulates cAMP production in thyroid cells, calf serum acts through ill-defined pathways to stimulate growth, and TPA is known to activate protein kinase C. Bovine calf serum and TSH acted synergistically to induce ornithine decarboxylase activity. Activity was maximal when the phosphodiesterase inhibitor, methyl isobutyl xanthine, was included. Individually, neither serum nor TSH was a potent stimulator of the enzyme. Ornithine decarboxylase mRNA was apparent on Northern blots as a doublet following one hour of exposure to these agents. TPA did not stimulate ornithine decarboxylase activity and had an inhibitory effect on enzyme induction by TSH and serum. Difluoromethylornithine, a specific inhibitor of ornithine decarboxylase, inhibited growth induced by both TPA and TSH in putrescine-free medium. This effect was not apparent in medium containing 10(-5) M putrescine. The data indicate that, although intracellular levels of cyclic AMP regulate ornithine decarboxylase activity, a component in serum is necessary for significant induction of this enzyme. Factors stimulating growth by non-cyclic AMP-dependent pathways may act without apparently stimulating this enzyme, although polyamines appear to be essential for their growth stimulatory effects. PMID:2483473

  9. Sesamin inhibits bacterial formylpeptide-induced inflammatory responses in a murine air-pouch model and in THP-1 human monocytes.

    PubMed

    Cui, Youhong; Hou, Xinwei; Chen, Juan; Xie, Lianying; Yang, Lang; Le, Yingying

    2010-02-01

    The reaction of human leukocytes to chemoattractants is an important component of the host immune response and also plays a crucial role in the development of inflammation. Sesamin has been shown to inhibit lipid peroxidation and regulate cytokine production. In this study, we examined the effect of sesamin on inflammatory responses elicited by the bacterial chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLF) in vitro and in vivo and explored the mechanisms involved. fMLF is recognized by a human G protein-coupled receptor formyl peptide receptor (FPR) on phagocytic leukocytes. Sesamin at concentrations between 12.5 and 50 micromol/L inhibited fMLF-induced chemotaxis of human monocyte cell line THP-1 differentiated with dibutyryl cyclic AMP (P < 0.01). Similarly, sesamin inhibited FPR-transfected rat basophilic leukemia cell [epitope-tagged human FPR (ETFR) cell] migration toward fMLF (P < 0.01). In fMLF-induced inflammation in a murine air-pouch model, intraperitoneal administration of sesamin (12 mgkg(-1)d(-1) for 2 d) suppressed leukocyte infiltration into the air pouch induced by fMLF [(62.89 +/- 7.93) x 10(4) vs. (19.67 +/- 4.43) x 10(4) cells/air pouch; n = 9; P < 0.001]. Ca(2+) mobilization and mitogen-activated protein kinase extracellular signal-regulated kinase (ERK1/2) activation are involved in fMLF-induced leukocyte migration. Pretreatment of ETFR cells with sesamin inhibited fMLF-induced ERK1/2 phosphorylation in a dose-dependent manner but did not affect fMLF-induced Ca(2+) flux. Electrophoretic mobility shift assay showed that pretreatment of THP-1 cells with sesamin dose dependently inhibited fMLF-induced nuclear factor-kappaB (NF-kappaB) activation. These results suggest that sesamin inhibits leukocyte activation by fMLF through ERK1/2- and NF-kappaB-related signaling pathways and thus is a potential compound for the management of inflammatory diseases. PMID:20032476

  10. Cytosolic DNA-activated Human Dendritic Cells are Potent Activators of the Adaptive Immune Response#

    PubMed Central

    Kis-Toth, Katalin; Szanto, Attila; Thai, To-Ha; Tsokos, George C.

    2011-01-01

    Recent studies in cell lines and genetically engineered mice have demonstrated that cytosolic double-stranded (ds) DNA could activate dendritic cells (DCs) to become effector antigen presenting cells. Recognition of DNA might be a major factor in antimicrobial immune responses against cytosolic pathogens and also in human autoimmune diseases such as systemic lupus erythematosus. However, the role of cytosolic dsDNA in human DC activation and its effects on effector T and B cells are still elusive. Here we demonstrate that intracellular dsDNA is a potent activator of human monocyte-derived DCs, as well as primary DCs. Activation by dsDNA depends on NF-?B activation, partially on the adaptor molecule IPS-1 and the novel cytosolic dsDNA receptor IFI16, but not on the previously recognized dsDNA sentinels AIM2, DAI, RNA polymerase III or HMGBs. More importantly, we report for the first time that human dsDNA-activated DCs, rather than LPS- or inflammatory cytokine cocktail-activated DCs, represent the most potent inducers of naïve CD4+ T cells to promote Th1-type cytokine production and to generate CD4+ and CD8+ cytotoxic T cells. dsDNA-, but not LPS- or cocktail-activated DCs induce B cells to produce complement fixing IgG1 and IgG3 antibodies. We propose that cytosolic dsDNA represents a novel, more effective approach to generate DCs to enhance vaccine effectiveness in reprogramming the adaptive immune system to eradicate infectious agents, autoimmunity, allergy and cancer. PMID:21709148

  11. Requirement for a Peptidoglycan Recognition Protein (PGRP) in Relish Activation and Antibacterial Immune Responses in Drosophila

    Microsoft Academic Search

    Kwang-Min Choe; Thomas Werner; Svenja Stöven; Dan Hultmark; Kathryn V. Anderson

    2002-01-01

    Components of microbial cell walls are potent activators of innate immune responses in animals. For example, the mammalian TLR4 signaling pathway is activated by bacterial lipopolysaccharide and is required for resistance to infection by Gram-negative bacteria. Other components of microbial surfaces, such as peptidoglycan, are also potent activators of innate immune responses, but less is known about how those components

  12. Structure of catabolite activator protein with cobalt(II) and sulfate.

    PubMed

    Rao, Ramya R; Lawson, Catherine L

    2014-05-01

    The crystal structure of cyclic AMP-catabolite activator protein (CAP) from Escherichia coli containing cobalt(II) chloride and ammonium sulfate is reported at 1.97 Å resolution. Each of the two CAP subunits in the asymmetric unit binds one cobalt(II) ion, in each case coordinated by N-terminal domain residues His19, His21 and Glu96 plus an additional acidic residue contributed via a crystal contact. The three identified N-terminal domain cobalt-binding residues are part of a region of CAP that is important for transcription activation at class II CAP-dependent promoters. Sulfate anions mediate additional crystal lattice contacts and occupy sites corresponding to DNA backbone phosphate positions in CAP-DNA complex structures. PMID:24817710

  13. Structure of catabolite activator protein with cobalt(II) and sulfate

    PubMed Central

    Rao, Ramya R.; Lawson, Catherine L.

    2014-01-01

    The crystal structure of cyclic AMP–catabolite activator protein (CAP) from Escherichia coli containing cobalt(II) chloride and ammonium sulfate is reported at 1.97?Å resolution. Each of the two CAP subunits in the asymmetric unit binds one cobalt(II) ion, in each case coordinated by N-terminal domain residues His19, His21 and Glu96 plus an additional acidic residue contributed via a crystal contact. The three identified N-terminal domain cobalt-binding residues are part of a region of CAP that is important for transcription activation at class II CAP-dependent promoters. Sulfate anions mediate additional crystal lattice contacts and occupy sites corresponding to DNA backbone phosphate positions in CAP–DNA complex structures. PMID:24817710

  14. Acute up-regulation of the rat brain somatostatin receptor-effector system by leptin is related to activation of insulin signaling and may counteract central leptin actions.

    PubMed

    Perianes-Cachero, A; Burgos-Ramos, E; Puebla-Jiménez, L; Canelles, S; Frago, L M; Hervás-Aguilar, A; de Frutos, S; Toledo-Lobo, M V; Mela, V; Viveros, M P; Argente, J; Chowen, J A; Arilla-Ferreiro, E; Barrios, V

    2013-11-12

    Leptin and somatostatin (SRIF) have opposite effects on food seeking and ingestive behaviors, functions partially regulated by the frontoparietal cortex and hippocampus. Although it is known that the acute suppression of food intake mediated by leptin decreases with time, the counter-regulatory mechanisms remain unclear. Our aims were to analyze the effect of acute central leptin infusion on the SRIF receptor-effector system in these areas and the implication of related intracellular signaling mechanisms in this response. We studied 20 adult male Wister rats including controls and those treated intracerebroventricularly with a single dose of 5 ?g of leptin and sacrificed 1 or 6h later. Density of SRIF receptors was unchanged at 1h, whereas leptin increased the density of SRIF receptors at 6h, which was correlated with an elevated capacity of SRIF to inhibit forskolin-stimulated adenylyl cyclase activity in both areas. The functional capacity of SRIF receptors was unaltered as cell membrane levels of ?i1 and ?i2 subunits of G inhibitory proteins were unaffected in both brain areas. The increased density of SRIF receptors was due to enhanced SRIF receptor subtype 2 (sst2) protein levels that correlated with higher mRNA levels for this receptor. These changes in sst2 mRNA levels were concomitant with increased activation of the insulin signaling, c-Jun and cyclic AMP response element-binding protein (CREB); however, activation of signal transducer and activator of transcription 3 was reduced in the cortex and unchanged in the hippocampus and suppressor of cytokine signaling 3 remained unchanged in these areas. In addition, the leptin antagonist L39A/D40A/F41A blocked the leptin-induced changes in SRIF receptors, leptin signaling and CREB activation. In conclusion, increased activation of insulin signaling after leptin infusion is related to acute up-regulation of the SRIF receptor-effector system that may antagonize short-term leptin actions in the rat brain. PMID:23973620

  15. Enterobacter-Activated Mosquito Immune Responses to Plasmodium Involve Activation of SRPN6 in Anopheles stephensi

    PubMed Central

    Jacobs-Lorena, Marcelo

    2013-01-01

    Successful development of Plasmodium in the mosquito is essential for the transmission of malaria. A major bottleneck in parasite numbers occurs during midgut invasion, partly as a consequence of the complex interactions between the endogenous microbiota and the mosquito immune response. We previously identified SRPN6 as an immune component which restricts Plasmodium berghei development in the mosquito. Here we demonstrate that SRPN6 is differentially activated by bacteria in Anopheles stephensi, but only when bacteria exposure occurs on the lumenal surface of the midgut epithelium. Our data indicate that AsSRPN6 is strongly induced following exposure to Enterobacter cloacae, a common component of the mosquito midgut microbiota. We conclude that AsSRPN6 is a vital component of the E. cloacae-mediated immune response that restricts Plasmodium development in the mosquito An. stephensi. PMID:23658788

  16. Neural activation in the orbitofrontal cortex in response to male faces increases during the follicular phase

    E-print Network

    James, Thomas

    also demon- strated increased limbic system activation in response to erotic videos during mid. These increases in neural responses to appetitive stimuli such as money and erotic videos (Dreher et al., 2007

  17. Responses of alkaline phosphatase activity in Daphnia to poor nutrition.

    PubMed

    Wagner, Nicole D; Frost, Paul C

    2012-09-01

    The use of biochemical and molecular indices of nutritional stress have recently been promoted for their potential ability to assess the in situ nutritional state of zooplankton. The development and application of these indicators should at least consider the cross-reactivity with other nutritional stressors. We examined the potential usefulness of body alkaline phosphatase activity (APA) as an indicator of dietary phosphorus (P) stress in Daphnia. We measured growth rate, body P-content, and body APA of two species of Daphnia (D. magna, D. pulex) grown for different periods under diverse dietary conditions. We found P-poor food reduced daphnid growth rates and body P-content, while body APA increased in both species. However, body APA increased in P-sufficient D. magna and D. pulex that were feeding on cyanobacterial compared to green algal food, despite no differences in animal body P content. Body APA increased in D. magna fed P-poor food whether cyanobacterial or algal. Body APA also varied with age and other nutritional stresses (low food quantity, nitrogen-poor algae) in both daphnid species. Our results demonstrate that whole body homogenate APA in Daphnia is not singularly responsive to P-poor food, which will complicate or limit its future usefulness and application as an indicator of dietary P-stress in metazoans. PMID:22327742

  18. Cytokine response is determined by duration of receptor and signal transducers and activators of transcription 3 (STAT3) activation.

    PubMed

    Braun, David A; Fribourg, Miguel; Sealfon, Stuart C

    2013-02-01

    Paradoxically, the pro-inflammatory cytokine IL-6 and the anti-inflammatory cytokine IL-10 both activate STAT3, yet generate nearly opposing cellular responses. Here, we show that the temporal pattern of STAT3 activation codes for the specific cytokine response. A computational model of IL-6 and IL-10 signaling predicted that IL-6 stimulation results in transient activation of STAT3, with a rapid decline in phosphorylation and nuclear localization. In contrast, simulated IL-10 signaling resulted in sustained STAT3 activation. The predicted STAT3 patterns produced by each cytokine were confirmed experimentally in human dendritic cells. Time course microarray studies further showed that the dynamic genome-wide transcriptional responses were nearly identical at early time points following stimulation (when STAT3 is active in response to both IL-6 and IL-10) but divergent at later times (when STAT3 is active only in response to IL-10). Truncating STAT3 activation after IL-10 stimulation caused IL-10 to elicit an IL-6-like transcriptional and secretory response. That the duration of IL-10 receptor and STAT3 activation can direct distinct responses reveals a complex cellular information-coding mechanism that may be relevant to improving the prediction of the effects of drug candidates using this mechanism. PMID:23166328

  19. Induction of early-response genes KC and JE by mycobacterial lipoarabinomannans: regulation of KC expression in murine macrophages by Lsh/Ity/Bcg (candidate Nramp).

    PubMed Central

    Roach, T I; Chatterjee, D; Blackwell, J M

    1994-01-01

    The murine chromosome 1 gene Lsh/Ity/Bcg (candidate Nramp) regulates macrophage activation for antimicrobial activity against Salmonella typhimurium, Leishmania donovani, and Mycobacterium spp. To determine early events in the activation pathway, the ability of mycobacterial lipoarabinomannan (LAM) to induce early gene (KC and JE) expression in macrophages from susceptible (S) C57BL/10ScSn (Lshs) and congenic resistant (R) B10.L-Lshr mice was investigated. Stimulation with 1.8 microgram of arabinofuranosyl-terminated LAM (AraLAM) per ml resulted in similar kinetics for KC or JE expression in S and R macrophages. However, whereas JE/glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA ratios remained equivalent, R macrophages consistently showed enhanced KC/GAPDH ratios within 30 to 40 min of stimulation compared with S macrophages. Significant differences in KC/GAPDH ratios were observed throughout the peak period (0.5 to 6 h) of the KC response and with doses of AraLAM ranging from 0.01 to 2.5 micrograms/ml. Heavily mannosylated LAM from virulent Mycobacterium tuberculosis Erdman, in doses of up to 2.5 micrograms/ml, failed to stimulate KC or JE in S or R macrophages. Gamma interferon alone (25 U/ml) stimulated equivalent JE expression in S and R macrophages and synergized with AraLAM to enhance JE in both. In contrast, AraLAM-induced KC expression was inhibited in the presence of gamma interferon. Agonist/inhibitor studies were undertaken to determine the signal transduction pathways mediating KC expression. The protein kinase C (PKC) inhibitor Calphostin C (200 nM) inhibited AraLAM-induced KC by 34% +/- 4% in S macrophages and 43% +/- 5% in R macrophages; the cyclic AMP-dependent PKA inhibitor KT5720 (2 microM) inhibited AraLAM-induced KC by 33% +/- 4% (S) and 25% +/- 5% (R). A role for Ca2+ was indicated because ionophore alone stimulated KC expression and synergized with AraLAM to give a dramatically enhanced response. Induction of KC was also inhibited by (i) blocking constitutive nitric oxide (NO) production by preincubation of macrophages with NG-monomethyl-L-arginine (400 microM) (48% +/- 8% [S] and 40% +/- 11% [R]) and (ii) incubation of macrophages with the cyclic GMP-dependent kinase inhibitor KT5823 (4 microM) (65% +/- 4% [S] and 72% +/- 6% [R]). The manner in which these PKC-, PKA-, and Ca(2+)-dependent, NO-mediated cyclic GMP-dependent kinase signal transduction pathways may relate to function of the candidate Lsh/Ity/Bcg gene Nramp is discussed. Images PMID:8132324

  20. Induction of early-response genes KC and JE by mycobacterial lipoarabinomannans: regulation of KC expression in murine macrophages by Lsh/Ity/Bcg (candidate Nramp).

    PubMed

    Roach, T I; Chatterjee, D; Blackwell, J M

    1994-04-01

    The murine chromosome 1 gene Lsh/Ity/Bcg (candidate Nramp) regulates macrophage activation for antimicrobial activity against Salmonella typhimurium, Leishmania donovani, and Mycobacterium spp. To determine early events in the activation pathway, the ability of mycobacterial lipoarabinomannan (LAM) to induce early gene (KC and JE) expression in macrophages from susceptible (S) C57BL/10ScSn (Lshs) and congenic resistant (R) B10.L-Lshr mice was investigated. Stimulation with 1.8 microgram of arabinofuranosyl-terminated LAM (AraLAM) per ml resulted in similar kinetics for KC or JE expression in S and R macrophages. However, whereas JE/glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA ratios remained equivalent, R macrophages consistently showed enhanced KC/GAPDH ratios within 30 to 40 min of stimulation compared with S macrophages. Significant differences in KC/GAPDH ratios were observed throughout the peak period (0.5 to 6 h) of the KC response and with doses of AraLAM ranging from 0.01 to 2.5 micrograms/ml. Heavily mannosylated LAM from virulent Mycobacterium tuberculosis Erdman, in doses of up to 2.5 micrograms/ml, failed to stimulate KC or JE in S or R macrophages. Gamma interferon alone (25 U/ml) stimulated equivalent JE expression in S and R macrophages and synergized with AraLAM to enhance JE in both. In contrast, AraLAM-induced KC expression was inhibited in the presence of gamma interferon. Agonist/inhibitor studies were undertaken to determine the signal transduction pathways mediating KC expression. The protein kinase C (PKC) inhibitor Calphostin C (200 nM) inhibited AraLAM-induced KC by 34% +/- 4% in S macrophages and 43% +/- 5% in R macrophages; the cyclic AMP-dependent PKA inhibitor KT5720 (2 microM) inhibited AraLAM-induced KC by 33% +/- 4% (S) and 25% +/- 5% (R). A role for Ca2+ was indicated because ionophore alone stimulated KC expression and synergized with AraLAM to give a dramatically enhanced response. Induction of KC was also inhibited by (i) blocking constitutive nitric oxide (NO) production by preincubation of macrophages with NG-monomethyl-L-arginine (400 microM) (48% +/- 8% [S] and 40% +/- 11% [R]) and (ii) incubation of macrophages with the cyclic GMP-dependent kinase inhibitor KT5823 (4 microM) (65% +/- 4% [S] and 72% +/- 6% [R]). The manner in which these PKC-, PKA-, and Ca(2+)-dependent, NO-mediated cyclic GMP-dependent kinase signal transduction pathways may relate to function of the candidate Lsh/Ity/Bcg gene Nramp is discussed. PMID:8132324

  1. Neuroprotective effects of hesperetin in mouse primary neurones are independent of CREB activation.

    PubMed

    Rainey-Smith, Stephanie; Schroetke, Lars-Wilhelm; Bahia, Parmvir; Fahmi, Ahmed; Skilton, Rachel; Spencer, Jeremy P E; Rice-Evans, Catherine; Rattray, Marcus; Williams, Robert J

    2008-06-13

    Dietary flavonoids, including the citrus flavanone hesperetin, may have stimulatory effects on cytoprotective intracellular signalling pathways. In primary mouse cortical neurone cultures, but not SH-SY5Y human neuroblastoma cells or human primary dermal fibroblasts (Promocells), hesperetin (100-300nM, 15min) caused significant increases in the level of ERK1/2 phosphorylation, but did not increase CREB phosphorylation. Administration of hesperetin for 18h did not alter gene expression driven by the cyclic AMP response element (CRE), assessed using a luciferase reporter system, but 300nM hesperetin partially reversed staurosporine-induced cell death in primary neurones. Our data show that hesperetin is a neuroprotective compound at concentrations where antioxidant effects are unlikely to predominate. The effects of hesperetin are cell-type dependent and, unlike the flavanol (-)epicatechin, neuroprotection in vitro is not associated with enhanced CREB phosphorylation or CRE-mediated gene expression. PMID:18467030

  2. Mouse ?3a- and ?3b-adrenoceptors expressed in Chinese hamster ovary cells display identical pharmacology but utilize distinct signalling pathways

    PubMed Central

    Hutchinson, Dana S; Bengtsson, Tore; Evans, Bronwyn A; Summers, Roger J

    2002-01-01

    This study characterizes the mouse ?3a-adrenoceptor (AR) and the splice variant of the ?3-AR (?3b-AR) expressed in Chinese hamster ovary cells (CHO-K1).Stable clones with high (?1200), medium (?500) or low receptor expression (?100?fmol?mg protein?1) were determined by saturation binding with [125I]-(?)-cyanopindolol. Competition binding studies showed no significant differences in affinity of ?-AR ligands for either receptor.Several functional responses of each receptor were measured, namely extracellular acidification rate (EAR; cytosensor microphysiometer), cyclic AMP accumulation, and Erk1/2 phosphorylation. The ?3-AR agonists BRL37344, CL316243, GR265162X, L755507, SB251023, the non-conventional partial ?-AR agonist CGP12177 and the ?-AR agonist (?)-isoprenaline caused concentration-dependent increases in EAR in cells expressing either splice variant. CL316243 caused concentration-dependent increases in cyclic AMP accumulation and Erk1/2 phosphorylation in cells expressing either receptor.PTX treatment increased maximum EAR and cyclic AMP responses to CL316243 in cells expressing the ?3b-AR but not in cells expressing the ?3a-AR at all levels of receptor expression.CL316243 increased Erk1/2 phosphorylation with pEC50 values and maximum responses that were not significantly different in cells expressing either splice variant. Erk1/2 phosphorylation was insensitive to PTX or H89 (PKA inhibitor) but was inhibited by LY294002 (PI3K? inhibitor), PP2 (c-Src inhibitor), genistein (tyrosine kinase inhibitor) and PD98059 (MEK inhibitor).The adenylate cyclase activators forskolin or cholera toxin failed to increase Erk1/2 levels although both treatments markedly increased cyclic AMP accumulation in both ?3a- or ?3b-AR transfected cells.These results suggest that in CHO-K1 cells, the ?3b-AR, can couple to both Gs and Gi to stimulate and inhibit cyclic AMP production respectively, while the ?3a-AR, couples solely to Gs to increase cyclic AMP levels. However, the increase in Erk1/2 phosphorylation following receptor activation is not dependent upon coupling of the receptors to Gi or the generation of cyclic AMP. PMID:11959793

  3. Diuretics and the renal adenylate cyclase system

    PubMed Central

    Dawborn, J.K.; Macneil, S.; Martin, T.J.

    1977-01-01

    1 The relationship between the diuretic effectiveness and the effect on the renal adenylate cyclase of three diuretics, acetazolamide, frusemide and ethacrynic acid, was examined. The hypothesis that acetazolamide and parathyroid hormone (PTH), inhibit renal carbonic anhydrase by a cyclic adenosine 3?,5?-monophosphate (cyclic AMP)-dependent mechanism was also tested. 2 In vitro, acetazolamide, frusemide and ethacrynic acid at high concentrations (10-3M) all produced some inhibition of basal and stimulated rat kidney plasma membrane adenylate cyclase. The effect of acetazolamide was much less than that of frusemide and ethacrynic acid. These plasma membrane effects were reproduced in studies of cyclic AMP formation in isolated kidney tubules of rats. 3 Intravenous injections of acetazolamide did not change the total cyclic AMP content of the kidneys of rats killed by microwave irradiation. 4 Acetazolamide produced a diuresis in the rat and a slight inhibition of the antidiuretic effect of Pitressin. Frusemide produced a diuresis and greatly reduced the antidiuretic response to Pitressin. Ethacrynic acid was ineffective as a diuretic in the rat and actually enhanced the antidiuretic response to Pitressin. 5 In investigating the possible influence of diuretics and PTH on the activity and state of phosphorylation of carbonic anhydrase it was found that: there was no correlation between the ability of diuretics to inhibit carbonic anhydrase activity and to inhibit carbonic anhydrase phosphorylation; neither PTH nor cyclic AMP (in the presence of adenosine triphosphate, Mg2+, K+ and incubation at 37°C) inhibited rat cortex homogenate carbonic anhydrase activity. 6 It seems unlikely that any of the tested diuretics exerts its pharmacological effect by means of changes in kidney cyclic AMP metabolism. PMID:202362

  4. The Effect of Tip Geometry on Active-Twist Rotor Response

    NASA Technical Reports Server (NTRS)

    Wilbur, Matthew L.; Sekula, Martin K.

    2005-01-01

    A parametric examination of the effect of tip geometry on active-twist rotor system response is conducted. Tip geometry parameters considered include sweep, taper, anhedral, nonlinear twist, and the associated radial initiation location for each of these variables. A detailed study of the individual effect of each parameter on active-twist response is presented, and an assessment offered of the effect of combining multiple tip shape parameters. Tip sweep is shown to have the greatest affect on active-twist response, significantly decreasing the response available. Tip taper and anhedral are shown to increase moderately the active-twist response, while nonlinear twist is shown to have a minimal effect. A candidate tip shape that provides active-twist response equivalent to or greater than a rectangular planform blade is presented.

  5. Efficient Generation of Cardiac Purkinje Cells from ESCs by Activating cAMP Signaling.

    PubMed

    Tsai, Su-Yi; Maass, Karen; Lu, Jia; Fishman, Glenn I; Chen, Shuibing; Evans, Todd

    2015-06-01

    Dysfunction of the specialized cardiac conduction system (CCS) is associated with life-threatening arrhythmias. Strategies to derive CCS cells, including rare Purkinje cells (PCs), would facilitate models for mechanistic studies and drug discovery and also provide new cellular materials for regenerative therapies. A high-throughput chemical screen using CCS:lacz and Contactin2:egfp (Cntn2:egfp) reporter embryonic stem cell (ESC) lines was used to discover a small molecule, sodium nitroprusside (SN), that efficiently promotes the generation of cardiac cells that express gene profiles and generate action potentials of PC-like cells. Imaging and mechanistic studies suggest that SN promotes the generation of PCs from cardiac progenitors initially expressing cardiac myosin heavy chain and that it does so by activating cyclic AMP signaling. These findings provide a strategy to derive scalable PCs, along with insight into the ontogeny of CCS development. PMID:26028533

  6. Efficient Generation of Cardiac Purkinje Cells from ESCs by Activating cAMP Signaling

    PubMed Central

    Tsai, Su-Yi; Maass, Karen; Lu, Jia; Fishman, Glenn I.; Chen, Shuibing; Evans, Todd

    2015-01-01

    Summary Dysfunction of the specialized cardiac conduction system (CCS) is associated with life-threatening arrhythmias. Strategies to derive CCS cells, including rare Purkinje cells (PCs), would facilitate models for mechanistic studies and drug discovery and also provide new cellular materials for regenerative therapies. A high-throughput chemical screen using CCS:lacz and Contactin2:egfp (Cntn2:egfp) reporter embryonic stem cell (ESC) lines was used to discover a small molecule, sodium nitroprusside (SN), that efficiently promotes the generation of cardiac cells that express gene profiles and generate action potentials of PC-like cells. Imaging and mechanistic studies suggest that SN promotes the generation of PCs from cardiac progenitors initially expressing cardiac myosin heavy chain and that it does so by activating cyclic AMP signaling. These findings provide a strategy to derive scalable PCs, along with insight into the ontogeny of CCS development. PMID:26028533

  7. Manipulation of endogenous kinase activity in living cells using photoswitchable inhibitory peptides.

    PubMed

    Yi, Jason J; Wang, Hui; Vilela, Marco; Danuser, Gaudenz; Hahn, Klaus M

    2014-11-21

    Optogenetic control of endogenous signaling can be an important tool for probing cell behavior. Using the photoresponse of the LOV2 domain of Avena sativa phototropin 1, we developed analogues of kinase inhibitors whose activity is light dependent. Inhibitory peptides were appended to the J? helix, where they potently inhibited kinases in the light but were sterically blocked from kinase interaction in the dark. Photoactivatable inhibitors for cyclic-AMP dependent kinase (PKA) and myosin light chain kinase (MLCK) are described, together with studies that shed light on proper positioning of the peptides in the LOV domain. These inhibitors altered endogenous signaling in living cells and produced light-dependent changes in cell morphodynamics. PMID:24905630

  8. The nitric oxide-cGKII system relays death and survival signals during embryonic retinal development via AKT-induced CREB1 activation

    PubMed Central

    Socodato, R; Brito, R; Portugal, C C; de Oliveira, N A; Calaza, K C; Paes-de-Carvalho, R

    2014-01-01

    During early neurogenesis, retinal neuronal cells display a conserved differentiation program in vertebrates. Previous studies established that nitric oxide (NO) and cGMP accumulation regulate essential events in retinal physiology. Here we used pharmacological and genetic loss-of-function to investigate the effects of NO and its downstream signaling pathway in the survival of developing avian retinal neurons in vitro and in vivo. Six-day-old (E6) chick retinal cells displayed increased calcium influx and produced higher amounts of NO when compared with E8 cells. L-arginine (substrate for NO biosynthesis) and S-nitroso-N-acetyl-D,L-penicillamine (SNAP; a nitrosothiol NO donor) promoted extensive cell death in E6 retinas, whereas in E8 both substances decreased apoptosis. The effect of NO at both periods was mediated by soluble guanylyl cyclase (sGC) and cGMP-dependent kinase (cGK) activation. In addition, shRNA-mediated cGKII knockdown prevented NO-induced cell death (E6) and cell survival (E8). This, NO-induced cell death or cell survival was not correlated with an early inhibition of retinal cell proliferation. E6 cells also responded differentially from E8 neurons regarding cyclic AMP-responsive element-binding protein (CREB) activation in the retina in vivo. NO strongly decreased nuclear phospho-CREB staining in E6 but it robustly enhanced CREB phosphorylation in the nuclei of E8 neurons, an effect that was completely abrogated by cGKII shRNAs at both embryonic stages. The ability of NO in regulating CREB differentially during retinal development relied on the capacity of cGKII in decreasing (E6) or increasing (E8) nuclear AKT (V-Akt murine thymoma viral oncogene) activation. Accordingly, inhibiting AKT prevented both cGKII shRNA-mediated CREB upregulation in E6 and SNAP-induced CREB activation in E8. Furthermore, shRNA-mediated in vivo cGKII or in vitro CREB1 knockdown confirmed that NO/cGKII dualistically regulated the downstream CREB1 pathway and caspase activation in the chick retina to modulate neuronal viability. These data demonstrate that NO-mediated cGKII signaling may function to control the viability of neuronal cells during early retinal development via AKT/CREB1 activity. PMID:24531539

  9. Loading and reflexes : the influence of body weight and active movements on reflex responses in humans

    Microsoft Academic Search

    Catharina Maria Bastiaanse

    2003-01-01

    This thesis describes six studies on the influence of active movements and body loading on reflex responses. To measure those influences healthy subjects were asked to walk with different loadings (e.g. a backpack) or with different active movements (e.g. arm swing) while different reflex responses were measured. After a general introduction (chapter 1), the studies are described. In chapter 2

  10. Gamma Band Unit Activity and Population Responses in the Pedunculopontine Nucleus

    E-print Network

    Hayar, Abdallah

    states (waking and paradoxical sleep), electroencephalographic (EEG) responses are characterized by low) is involved in the activated states of waking and paradoxical sleep, forming part of the reticular activating system (RAS). The studies described tested the hypothesis that single unit and/or population responses

  11. Sleepy Watermark Tracing: An Active Network-Based Intrusion Response Framework*

    E-print Network

    Wang, Xinyuan "Frank"

    Sleepy Watermark Tracing: An Active Network- Based Intrusion Response Framework* Xinyuan Wang of California at Davis USA Key words: Intrusion Response, Intrusion Tracing, Active Security, and Network Security Abstract: Network-based intrusion has become a serious threat to today's highly networked

  12. Involvement of tissue plasminogen activator in stress responsivity during acute cocaine withdrawal in mice

    E-print Network

    Involvement of tissue plasminogen activator in stress responsivity during acute cocaine withdrawal to stress responsivity during cocaine withdrawal (WD). Recent studies suggest that tissue plasminogen activator (tPA) in the CeA is a downstream effector protein for CRF after acute "binge" cocaine

  13. Human Amygdala Activity During the Expression of Fear Responses Dominic T. Cheng, David C. Knight, and

    E-print Network

    Squire, Larry R.

    Human Amygdala Activity During the Expression of Fear Responses Dominic T. Cheng, David C. Knight of Pavlovian fear conditioning suggest that the amygdala is important for both forming stimulus associations and for subsequently expressing learned behavioral responses. In the present article, human amygdala activity

  14. Artery active mechanical response: High order finite element implementation and investigation

    E-print Network

    Yosibash, Zohar

    to the passive mechanical response due to the elastin and collagen fibers (well investigated in past studies the SEDFs are formulated to result in a stress-strain response that mimics the experimentally observed reArtery active mechanical response: High order finite element implementation and investigation Zohar

  15. Phosphatidylinositol 3-kinase-dependent, MEK-independent proliferation in response to CaR activation

    SciTech Connect

    Bilderback, Tim R.; Lee, Fred; Auersperg, Nelly; Rodland, Karin D.

    2002-07-02

    Although ovarian surface epithelial (OSE) cells are responsible for the majority of ovarian tumors, we know relatively little about the pathway(s) that are responsible for regulating their proliferation. We found that phosphatidylinositol 3-kinase (PI3K) is activated in OSE cells in response to elevated extracellular calcium, and the PI3K inhibitors wortmannin and LY29004 inhibited ERK activation by approximately 75%, similar to effects of the MEK2 inhibitor PD98059. However, in assays of proliferation we found that PD98059 inhibited proliferation by approximately 50%, while wortmannin inhibited greater than 90% of the proliferative response to elevated calcium. Expression of a dominant negative PI3K totally inhibited ERK activation in response to calcium. These results demonstrate that ERK activation cannot account for the full proliferative effect of elevated calcium in OSE cells, and suggest the presence of an ERK independent, PI3K dependant component in the proliferative response.

  16. Contribution of the ciliary cyclic nucleotide-gated conductance to olfactory transduction in the salamander.

    PubMed Central

    Lowe, G; Gold, G H

    1993-01-01

    1. Flash photolysis of caged cyclic nucleotides was used to examine the contribution of the ciliary cyclic nucleotide-gated conductance to olfactory transduction in the tiger salamander. Brief illumination of solitary olfactory receptor cells loaded with 100 microM caged cyclic AMP caused a large inward current (peak amplitude 355 +/- 200 pA; mean +/- S.D. for eleven cells) under whole-cell voltage clamp at -50 mV. 2. The photolysis response was initiated after a latency of 4-12 ms, whereas an odorant response of identical amplitude had a latency of several hundred milliseconds. The amplitudes of both responses exhibited almost identical voltage dependence between -50 and +25 mV, with both reversing near 0 mV. The time courses of the falling phases of odorant and photolysis responses also exhibited similar voltage dependence, both being prolonged at positive voltages. 3. Photolysis of caged cyclic GMP activated a current similar in amplitude and time course to that produced by photolysis of caged cyclic AMP. 4. When the flash was spatially limited to the cilia, the amplitude and duration of the photolysis response increased linearly with the length of the cilia illuminated (for cilia not longer than 30-40 microns) while the latency remained constant at 4-12 ms. The increase in duration was described semi-quantitatively by a model which incorporated diffusion and saturable hydrolysis of cyclic AMP. When the flash was limited to the soma or proximal dendrite, the response latency was proportional to the square of the distance between the illuminated region and the cilia. 5. Dialysis of cells with 500 microM cyclic AMP from a whole-cell electrode under voltage clamp activated a large transient inward current. Simultaneous suction electrode recording showed that this current originated almost entirely from the ciliary membrane. The density of cyclic nucleotide-gated channels was estimated to be 800-fold higher in the cilia than in the soma. 6. Summation of simultaneous odorant and photolysis responses was non-linear, the flash-induced current being enhanced during a small odorant response and attenuated during a large odorant response. Summation of two photolysis responses was similarly non-linear. The data were consistent with odorant stimuli and cyclic AMP both activating a common cyclic nucleotide-gated conductance with a Hill coefficient, n, of 2.0-4.4. For n = 2.5, the basal cyclic AMP concentration was estimated to be less than 20% of the K 1/2, which predicts a basal current of 5.8 pA, less than 2% of the maximum.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8392566

  17. Candida albicans Czf1 and Efg1 Coordinate the Response to Farnesol during Quorum Sensing, White-Opaque Thermal Dimorphism, and Cell Death

    PubMed Central

    Langford, Melanie L.; Hargarten, Jessica C.; Patefield, Krista D.; Marta, Elizabeth; Blankenship, Jill R.; Fanning, Saranna; Nickerson, Kenneth W.

    2013-01-01

    Quorum sensing by farnesol in Candida albicans inhibits filamentation and may be directly related to its ability to cause both mucosal and systemic diseases. The Ras1-cyclic AMP signaling pathway is a target for farnesol inhibition. However, a clear understanding of the downstream effectors of the morphological farnesol response has yet to be unraveled. To address this issue, we screened a library for mutants that fail to respond to farnesol. Six mutants were identified, and the czf1?/czf1? mutant was selected for further characterization. Czf1 is a transcription factor that regulates filamentation in embedded agar and also white-to-opaque switching. We found that Czf1 is required for filament inhibition by farnesol under at least three distinct environmental conditions: on agar surfaces, in liquid medium, and when embedded in a semisolid agar matrix. Since Efg1 is a transcription factor of the Ras1-cyclic AMP signaling pathway that interacts with and regulates Czf1, an efg1?/efg1? czf1?/czf1? mutant was tested for filament inhibition by farnesol. It exhibited an opaque-cell-like temperature-dependent morphology, and it was killed by low farnesol levels that are sublethal to wild-type cells and both efg1?/efg1? and czf1?/czf1? single mutants. These results highlight a new role for Czf1 as a downstream effector of the morphological response to farnesol, and along with Efg1, Czf1 is involved in the control of farnesol-mediated cell death in C. albicans. PMID:23873867

  18. 77 FR 66830 - Agency Information Collection Activities OMB Responses

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-07

    ...Request (ICR) Number. SUPPLEMENTARY INFORMATION: OMB Responses To Agency Clearance Requests OMB Approvals EPA ICR Number 1587.12; State Operating Permit Regulations; 40 CFR part 70; was approved on 10/03/2012; OMB Number 2060-0243;...

  19. WATER: Water Activities Teaching Environmental Responsibility: Teacher Resource, Environmental Science.

    ERIC Educational Resources Information Center

    Kramer, Ed, Ed.; And Others

    This activity book was developed as part of an effort to protect water quality of the Stillwater River, Ohio, through a Watershed Protection Project. It is designed to raise teachers' and students' awareness and trigger a sense of stewardship towards the preservation of water resources. The activities are generally appropriate for elementary age…

  20. Outdoor Activities as a Basis for Environmental Responsibility.

    ERIC Educational Resources Information Center

    Palmberg, Irmeli E.; Kuru, Jari

    2000-01-01

    Discusses experiences with outdoor activities involving 11- and 12-year-old pupils in Finland. Indicates that nature experiences develop pupils' self-confidence and feelings of safety, which in turn increases their willingness to participate in future outdoor activities. (Contains 17 references.) (Author/ASK)

  1. Controlling NK Cell Responses: Integration of Signals for Activation and Inhibition

    PubMed Central

    Long, Eric O.; Kim, Hun Sik; Liu, Dongfang; Peterson, Mary E.; Rajagopalan, Sumati

    2013-01-01

    Understanding how signals are integrated to control NK cell responsiveness in the absence of antigen-specific receptors has been a challenge, but recent work has revealed some underlying principles that govern NK cell responses. NK cells use an array of innate receptors to sense their environment and respond to alterations caused by infections, cellular stress and transformation. No single activation receptor dominates; instead, synergistic signals from combinations of receptors are integrated to activate natural cytotoxicity and cytokine production. Inhibitory receptors for MHC class I have a critical role in controlling NK cell responses and paradoxically, in maintaining NK cells in a state of responsiveness to subsequent activation events, a process referred to as licensing. MHC-I specific inhibitory receptors both block activation signals and trigger signals to phosphorylate and inactivate the small adaptor Crk. These different facets of inhibitory signaling are incorporated into a revocable license model for the reversible tuning of NK cell responsiveness. PMID:23516982

  2. The Effects of the Perceived Motivation Type toward Corporate Social Responsibility Activities on Customer Loyalty

    Microsoft Academic Search

    Kyungjin Kim

    2009-01-01

    Corporate social responsibility (CSR) activities have been shown to be potential factors that can improve corporate image and increase the ability of corporations to compete. However, most previous studies related to CSR activities investigated how these activities influence product and corporate evaluation, as well as corporate image. In addition, some researchers treated consumers’ perceptions of corporate motives as moderator variables

  3. CREB activity in the nucleus accumbens shell controls gating of behavioral responses to emotional stimuli

    Microsoft Academic Search

    Michel Barrot; Jocelien D. A. Olivier; Linda I. Perrotti; Ralph J. Dileone; Olivier Berton; Amelia J. Eisch; Soren Impey; Daniel R. Storm; Rachael L. Neve; Jerry C. Yin; Venetia Zachariou; Eric J. Nestler

    2002-01-01

    The transcription factor cAMP response element (CRE)-binding protein (CREB) has been shown to regulate neural plasticity. Drugs of abuse activate CREB in the nucleus accumbens, an important part of the brain's reward pathways, and local manipulations of CREB activity have been shown to affect cocaine reward, suggesting an active role of CREB in adaptive processes that follow exposure to drugs

  4. Fear Is Fast in Phobic Individuals: Amygdala Activation in Response to Fear-Relevant Stimuli

    E-print Network

    Fear Is Fast in Phobic Individuals: Amygdala Activation in Response to Fear-Relevant Stimuli and resistance to cognitive regulation. We hypothesized that activation of the amygdala early in the presentation of amygdala activation to phobia-relevant pictures was assessed in 13 spider phobics and 14 nonphobics using

  5. Dual function of CD70 in viral infection: modulator of early cytokine responses and activator of adaptive responses1

    PubMed Central

    Allam, Atef; Swiecki, Melissa; Vermi, William; Ashwell, Jonathan D.; Colonna, Marco

    2014-01-01

    The role of the tumor necrosis factor family member CD70 in adaptive T cell responses has been intensively studied but its function in innate responses is still under investigation. Here we show that CD70 inhibits the early innate response to murine cytomegalovirus (MCMV) but is essential for the optimal generation of virus-specific CD8 T cells. CD70-/- mice reacted to MCMV infection with a robust type I interferon and proinflammatory cytokine response. This response was sufficient for initial control of MCMV, although at later time points, CD70-/- mice became more susceptible to MCMV infection. The heightened cytokine response during the early phase of MCMV infection in CD70-/- mice was paralleled by a reduction in regulatory T cells (Treg). Treg from naïve CD70-/- mice were not as efficient at suppressing T cell proliferation compared to Treg from naïve WT mice and depletion of Treg during MCMV infection in Foxp3-DTR mice or in WT mice recapitulated the phenotype observed in CD70-/- mice. Our study demonstrates that while CD70 is required for the activation of the antiviral adaptive response, it has a regulatory role in early cytokine responses to viruses such as MCMV, possibly through maintenance of Treg survival and function. PMID:24913981

  6. Nonconscious activation of placebo and nocebo pain responses

    E-print Network

    Jensen, Karin B.

    The dominant theories of human placebo effects rely on a notion that consciously perceptible cues, such as verbal information or distinct stimuli in classical conditioning, provide signals that activate placebo effects. ...

  7. Inotropic responses of the frog ventricle to adenosine triphosphate and related changes in endogenous cyclic nucleotides.

    PubMed Central

    Flitney, F W; Singh, J

    1980-01-01

    1. A study has been made of a well documented but poorly understood response of the isolated frog ventricle to treatment with exogenous adenosine 5' triphosphate (ATP). Measurements of membrane potential, isometric twitch tension and levels of endogenous 3',5'-cyclic nucleotides have been made at various times during the ATP-induced response. 2. ATP elicits a characteristic triphasic response, which comprises an initial, abrupt increase in contractility, rising to a maximum within a few beats (first phase); followed by a period when the twitch amplitude falls, sometimes to below the control level (second phase); and superceded by a more slowly developing and longer-lasting increase in contractile force (third phase). The response is unaffected by atropine, propranolol or phentolamine. However, the prostaglandin synthetase inhibitor indomethacin depresses the first phase and entirely suppresses the third phase. 3. The inotropic effects of ATP are accompanied by changes in the shape of the action potential. These effects are dose-related. The duration of the action potential (D-30mV) and its positive overshoot (O) are increased during all phases of the response, for [ATP]o's up to 10(-5) M. However, at higher [ATP]o's, D-30mV and O ar both reduced during the second phase (but not the first or third phase), when isometric twitch tension is also depressed. The relationship between action potential duration and twitch tension (P) for different [ATP]o's is linear for all three phases of the response, but the slopes of the curves (delta P/delta D) are markedly different, indicating that the sensitivity of the contractile system to membrane depolarization is not constant, but varies continuously throughout the response. 4. ATP has a potent stimulatory effect on the metabolism of endogenous 3',5'-cyclic nucleotides. The time courses of the changes in adenosine 3','5-cyclic monophosphate (3',5'-cyclic AMP) and guanosine 3',5'-cyclic monophosphate (3',5'-cyclic GMP) are complex, but the accompanying change in isometric twitch tension is paralleled closely by corresponding changes in the ratio 3',5'cyclic AMP:3',5'-cyclic GMP. 5. It is concluded that ATP exerts a dual effect on the ventricle and that the contractile response is regulated by changes in the metabolism of 3',5'-cyclic nucleotides. The effects of indomethacin indicate a possible involvement of prostaglandins in mediating the ATP response. It is suggested that the initial effect of ATP on the ventricle is to increase the permeability of the fibres to Ca2+. 6. The relationship between 3',5' cyclic nucleotide levels and ventricular contractility is discussed. It is postulated that the antagonistic effects of 3',5'-cyclic AMP and 3',5'-cyclic GMP are expressed at the level of certain phosphoproteins which regulate both the availability of Ca2+ and the sensitivity of the contractile proteins to Ca2+. PMID:6255141

  8. Bald Eagle response to boating activity in northcentral Florida

    USGS Publications Warehouse

    Wood, P.B.

    1999-01-01

    I examined the effects of weekend and weekday boating activity on Bald Eagle (Haliaeetus leucocephalus) use of three lakes in northcentral Florida during 1988-89. On Lake Lochloosa, which had the highest number of boats of the three lakes, boating activity significantly reduced the numbers of all age classes of eagles using the lake (P < 0.025). Increased boating activity on Lake Wauberg was not related to use by eagles (P = 0.06) likely because boating activity was concentrated during midday while eagles typically foraged early and late in the day. On Newnan's Lake, the number of eagles observed also was not different between weekends and weekdays (P = 0.20). Weekend boating activity did not relate to perch use, habitat use, interactions or age distribution indicating no alteration of eagle behavior patterns. Flush distance did not vary between weekends and weekdays (P = 0.96), but did vary by month (P = 0.0001), with a greater flush distance during months with highest boating activity. Minimal flush distances (x?? = 53m) and lack of measurable effects on behavior suggested that eagles in my study area were tolerant of boat disturbance.

  9. Motor Activation From Visible Speech: Evidence From Stimulus Response Compatibility

    Microsoft Academic Search

    Dirk Kerzel; Harold Bekkering

    2000-01-01

    In speech perception, phonetic information can be acquired optically as well as acoustically. The motor theory of speech perception holds that motor control structures are involved in the processing of visible speech, whereas perceptual accounts do not make this assumption. Motor involvement in speech perception was examined by showing participants response-irrelevant movies of a mouth articulating \\/b&Lgr\\/ or \\/d&Lgr\\/ and

  10. Dynamic structure of joint-action stimulus-response activity.

    PubMed

    Malone, MaryLauren; Castillo, Ramon D; Kloos, Heidi; Holden, John G; Richardson, Michael J

    2014-01-01

    The mere presence of a co-actor can influence an individual's response behavior. For instance, a social Simon effect has been observed when two individuals perform a Go/No-Go response to one of two stimuli in the presence of each other, but not when they perform the same task alone. Such effects are argued to provide evidence that individuals co-represent the task goals and the to-be-performed actions of a co-actor. Motivated by the complex-systems approach, the present study was designed to investigate an alternative hypothesis--that such joint-action effects are due to a dynamical (time-evolving) interpersonal coupling that operates to perturb the behavior of socially situated actors. To investigate this possibility, participants performed a standard Go/No-Go Simon task in joint and individual conditions. The dynamic structure of recorded reaction times was examined using fractal statistics and instantaneous cross-correlation. Consistent with our hypothesis that participants responding in a shared space would become behaviorally coupled, the analyses revealed that reaction times in the joint condition displayed decreased fractal structure (indicative of interpersonal perturbation processes modulating ongoing participant behavior) compared to the individual condition, and were more correlated across a range of time-scales compared to the reaction times of pseudo-pair controls. Collectively, the findings imply that dynamic processes might underlie social stimulus-response compatibility effects and shape joint cognitive processes in general. PMID:24558467

  11. Signal-Regulated Activation of Serum Response Factor Is Mediated by Changes in Actin Dynamics

    Microsoft Academic Search

    Athanassia Sotiropoulos; Dziugas Gineitis; John Copeland; Richard Treisman

    1999-01-01

    Serum response factor (SRF) regulates transcription of many serum-inducible and muscle-specific genes. Using a functional screen, we identified LIM kinase-1 as a potent activator of SRF. We show that SRF activation by LIM kinase-1 is dependent on its ability to regulate actin treadmilling. LIM kinase activity is not essential for SRF activation by serum, but signals depend on alterations in

  12. Response of alkali activated fly ash mortars to microwave curing

    Microsoft Academic Search

    Jeevaka Somaratna; Deepak Ravikumar; Narayanan Neithalath

    2010-01-01

    Volumetric heating provided by microwave curing results in faster property development as compared to conventional heat curing that relies on heat conduction from the skin to the core. This paper discusses the compressive strength and microstructure development of microwave cured NaOH activated fly ash mortars, and relates them to the microwave energy absorption by the material which is a function

  13. Oculomotor Responses to Active Head Movements in Darkness

    E-print Network

    Ramat, Stefano

    velocity in space; = eye position in the orbit; ED = desired eye position in the orbit; = vestibular mechanism produces the fast phases. A similar pattern of eye movements can be evoked by active head rotations in darkness, suggesting that vestibular nystagmus represents a specific strategy of eye

  14. Norepinephrine Controls Astroglial Responsiveness to Local Circuit Activity

    E-print Network

    Bergles, Dwight

    simulta- neous activation of astrocyte networks in multiple brain regions. This global stimulation the brain. Although astrocytes in visual cortex of awake mice were rarely engaged when neurons were of astrocytes on various aspects of brain physiology is controlled by these metabotropic receptors. Nevertheless

  15. Mechanisms of transcriptional activation of estrogen responsive genes in breast cancer cells 

    E-print Network

    Chen, Chien-Cheng

    2009-06-02

    Estrogen receptor (ER) acts as a ligand-activated transcription factor that regulates the expression of genes. The genomic mechanisms of ER action include ligand-induced dimerization of ER which binds estrogen responsive ...

  16. ISS Update: Active Response Gravity Offload System -- 08.24.12 - Duration: 5 minutes, 35 seconds.

    NASA Video Gallery

    NASA Public Affairs Officer Brandi Dean talks to the Active Response Gravity Offload System (ARGOS) Project Manager Larry Dungan in the Space Vehicle Mock-Up Facility at Johnson Space Center in Hou...

  17. Spatial and temporal winter territory use and behavioral responses of whooping cranes to human activities 

    E-print Network

    LaFever, Kristin E.

    2009-06-02

    I investigated spatial and temporal winter behavior and behavioral responses of 5 territorial whooping crane families to human activities at Aransas National Wildlife Refuge during winters 2003-2004 and 2004-2005. Adult ...

  18. Complexity of the primary genetic response to mitogenic activation of human T cells

    SciTech Connect

    Zipfel, P.F.; Siebenlist, U. (National Inst. of Allergy and Infectious Diseases, Bethesda, MD (USA)); Irving, S.G.; Kelly, K. (National Cancer Inst., Bethesda, MD (USA))

    1989-03-01

    The authors describe the isolation and characterization of more than 60 novel cDNA clones that constitute part of the immediate genetic response to resting human peripheral blood T cells after mitogen activation. This primary response was highly complex, both in the absolute number of inducible genes and in the diversity of regulation. Although most of the genes expressed in activated T cells were shared with the activation response of normal human fibroblasts, a significant number were more restricted in tissue specificity and thus likely encode or effect the differentiated functions of activated T cells. The activatable genes could be further differentiated on the basis of kinetics of induction, response to cycloheximide, and sensitivity to the immunosuppressive drug cylcosporin A. It is of note that cyclosporin A inhibited the expression of more than 10 inducible genes, which suggests that this drug has a broad genetic mechanism of action.

  19. Glucose-6-phosphate mediates activation of the carbohydrate responsive binding protein (ChREBP)

    SciTech Connect

    Li, Ming V. [Program of Cardiovascular Sciences, Houston, TX 77030 (United States) [Program of Cardiovascular Sciences, Houston, TX 77030 (United States); Departments of Medicine and Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030 (United States); Chen, Weiqin [Departments of Medicine and Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030 (United States)] [Departments of Medicine and Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030 (United States); Harmancey, Romain N. [Division of Cardiology, The University of Texas Health Science Center at Houston, Houston, TX 77030 (United States)] [Division of Cardiology, The University of Texas Health Science Center at Houston, Houston, TX 77030 (United States); Nuotio-Antar, Alli M.; Imamura, Minako; Saha, Pradip [Departments of Medicine and Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030 (United States)] [Departments of Medicine and Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030 (United States); Taegtmeyer, Heinrich [Division of Cardiology, The University of Texas Health Science Center at Houston, Houston, TX 77030 (United States)] [Division of Cardiology, The University of Texas Health Science Center at Houston, Houston, TX 77030 (United States); Chan, Lawrence, E-mail: lchan@bcm.tmc.edu [Program of Cardiovascular Sciences, Houston, TX 77030 (United States) [Program of Cardiovascular Sciences, Houston, TX 77030 (United States); Departments of Medicine and Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030 (United States); St. Luke's Episcopal Hospital, Houston, TX 77030 (United States)

    2010-05-07

    Carbohydrate response element binding protein (ChREBP) is a Mondo family transcription factor that activates a number of glycolytic and lipogenic genes in response to glucose stimulation. We have previously reported that high glucose can activate the transcriptional activity of ChREBP independent of the protein phosphatase 2A (PP2A)-mediated increase in nuclear entry and DNA binding. Here, we found that formation of glucose-6-phosphate (G-6-P) is essential for glucose activation of ChREBP. The glucose response of GAL4-ChREBP is attenuated by D-mannoheptulose, a potent hexokinase inhibitor, as well as over-expression of glucose-6-phosphatase (G6Pase); kinetics of activation of GAL4-ChREBP can be modified by exogenously expressed GCK. Further metabolism of G-6-P through the two major glucose metabolic pathways, glycolysis and pentose-phosphate pathway, is not required for activation of ChREBP; over-expression of glucose-6-phosphate dehydrogenase (G6PD) diminishes, whereas RNAi knockdown of the enzyme enhances, the glucose response of GAL4-ChREBP, respectively. Moreover, the glucose analogue 2-deoxyglucose (2-DG), which is phosphorylated by hexokinase, but not further metabolized, effectively upregulates the transcription activity of ChREBP. In addition, over-expression of phosphofructokinase (PFK) 1 and 2, synergistically diminishes the glucose response of GAL4-ChREBP. These multiple lines of evidence support the conclusion that G-6-P mediates the activation of ChREBP.

  20. Cooperative phosphorylation at multiple sites is required to activate p53 in response to UV radiation

    Microsoft Academic Search

    Mini Kapoor; Rebecca Hamm; Wen Yan; Yoichi Taya; Guillermina Lozano

    2000-01-01

    The activity of the tumor suppressor p53 is induced in response to DNA-damaging agents such as UV and ? radiation. Phosphorylation is one of the key regulatory steps for activating p53 function. Recent reports have shown that p53 is phosphorylated at both serines 15 and 392 in response to UV radiation. Phosphorylation at serine 15 prevents the binding of HDM2,

  1. 256-site Active Neural Probe and 64-channel Responsive Cortical Stimulator

    E-print Network

    Genov, Roman

    responsive electrical stimulation before the onset of a seizure often prevents the development of the seizure inductively through the skin. In this paper we present the design of the neural recording and stimulation256-site Active Neural Probe and 64-channel Responsive Cortical Stimulator R. Shulyzki, K

  2. Evaluation of Social Cognitive Scaling Response Options in the Physical Activity Domain

    ERIC Educational Resources Information Center

    Rhodes, Ryan E.; Matheson, Deborah Hunt; Mark, Rachel

    2010-01-01

    The purpose of this study was to compare the reliability, variability, and predictive validity of two common scaling response formats (semantic differential, Likert-type) and two numbers of response options (5-point, 7-point) in the physical activity domain. Constructs of the theory of planned behavior were chosen in this analysis based on its…

  3. The Response of US College Enrollment to Unexpected Changes in Macroeconomic Activity

    ERIC Educational Resources Information Center

    Ewing, Kris M.; Beckert, Kim A.; Ewing, Bradley T.

    2010-01-01

    This paper estimates the extent and magnitude of US college and university enrollment responses to unanticipated changes in macroeconomic activity. In particular, we consider the relationship between enrollment, economic growth, and inflation. A time series analysis known as a vector autoregression is estimated and impulse response functions are…

  4. The Responses of Preschoolers with Cochlear Implants to Musical Activities: A Multiple Case Study

    ERIC Educational Resources Information Center

    Schraer-Joiner, Lyn E.; Chen-Hafteck, Lily

    2009-01-01

    The purpose of this study was to investigate the musical experiences of preschool cochlear implant users. Research objectives were to examine: (1) musical, social and emotional responses to activities; and (2) whether length of experience with the implant influenced responses. Participants were three prelingually deafened children, age 4,…

  5. Relation between abnormal patterns of muscle activation and response to common peroneal nerve stimulation in hemiplegia

    Microsoft Academic Search

    J H Burridge; D L McLellan

    2000-01-01

    OBJECTIVETo investigate the relation between response to common peroneal nerve stimulation, timed to the swing phase of walking, and abnormal ankle movement and muscle activation patterns.METHODEighteen patients who took part had a drop foot and had had a stroke at least 6 months before the study Twelve age matched normal subjects were also studied. Response to stimulation was measured by

  6. Modeling the dynamic response of camels' heart rate to physical activities

    Microsoft Academic Search

    Techane Bosona; Girma Gebresenbet; Fufa S. Bulitta

    2011-01-01

    This paper presents the result of the study made on the dynamic response of camels' heart rate (HR) under working conditions. The main objective was to develop a simulation model that can describe the dynamic nature of the camels' heart rate response to physical activity i.e. pulling a loaded cart and sledge. The dynamic simulation model was developed using Powersim

  7. Tissue plasminogen activator modulates the cellular and behavioral response to cocaine

    E-print Network

    Tissue plasminogen activator modulates the cellular and behavioral response to cocaine Rajani, 2008 (received for review April 6, 2008) Cocaine exposure induces long-lasting molecular and structural protease involved in neuronal plasticity, modulates the biochemical and behavioral response to cocaine

  8. Virulent Type A Francisella tularensis actively suppresses cytokine responses in human monocytes

    PubMed Central

    Gillette, Devyn D.; Curry, Heather M.; Cremer, Thomas; Ravneberg, David; Fatehchand, Kavin; Shah, Prexy A.; Wewers, Mark D.; Schlesinger, Larry S.; Butchar, Jonathan P.; Tridandapani, Susheela; Gavrilin, Mikhail A.

    2014-01-01

    Background: Human monocyte inflammatory responses differ between virulent and attenuated Francisella infection. Results: A mixed infection model showed that the virulent F. tularensis Schu S4 can attenuate inflammatory cytokine responses to the less virulent F. novicida in human monocytes. Conclusion: F. tularensis dampens inflammatory response by an active process. Significance: This suppression may contribute to enhanced pathogenicity of F. tularensis. Francisella tularensis is a Gram-negative facultative bacterium that can cause the disease tularemia, even upon exposure to low numbers of bacteria. One critical characteristic of Francisella is its ability to dampen or subvert the host immune response. Previous work has shown that monocytes infected with highly virulent F. tularensis subsp. tularensis strain Schu S4 responded with a general pattern of quantitatively reduced pro-inflammatory signaling pathway genes and cytokine production in comparison to those infected with the less virulent related F. novicida. However, it has been unclear whether the virulent Schu S4 was merely evading or actively suppressing monocyte responses. By using mixed infection assays with F. tularensis and F. novicida, we show that F. tularensis actively suppresses monocyte pro-inflammatory responses. Additional experiments show that this suppression occurs in a dose-dependent manner and is dependent upon the viability of F. tularensis. Importantly, F. tularensis was able to suppress pro-inflammatory responses to earlier infections with F. novicida. These results lend support that F. tularensis actively dampens human monocyte responses and this likely contributes to its enhanced pathogenicity. PMID:24783062

  9. ENDOCRINE ACTIVE SUBSTANCES AND DOSE-RESPONSE FOR INDIVIDUALS AND POPULATIONS

    EPA Science Inventory

    Endocrine Active Substances and Dose-Response for Individuals and Populations Hugh A. Barton Abstract for IUPAC-SCOPE article Dose-response characteristics for endocrine disruption have been major focuses in efforts to understand potential impacts on human and ec...

  10. Aberrant mTOR activation in senescence and aging: A mitochondrial stress response?

    PubMed

    Nacarelli, Timothy; Azar, Ashley; Sell, Christian

    2015-08-01

    Unexpected activation of mTOR signaling, measured by ribosomal S6 phosphorylation or ribosomal S6 kinase (p70S6K) activity, has been reported in aging-related settings. Evidence of elevated mTOR activity has been reported in the heart and muscle tissue in aged mice and humans, mouse models of progeria, and senescent human fibroblasts. We explore these reports and the possibility that activation of the mTOR/p70S6K kinase pathway may represent a ROS-mediated response to mitochondrial stress leading to the activation of senescence. This activation is a hallmark of both aged tissue and senescent human cells. PMID:25449851

  11. Pronociceptive response elicited by TRPA1 receptor activation in mice

    Microsoft Academic Search

    E. L. Andrade; A. P. Luiz; J. Ferreira; J. B. Calixto

    2008-01-01

    Ankyrin-repeat transient receptor potential 1 (TRPA1) is a member of the transient receptor potential (TRP) channel family and it is found in sensory neurons. In the present study, we found that TRPA1 receptor activation with allyl isothiocyanate or cinnamaldehyde caused dose-dependent spontaneous nociception when injected into the mouse hind paw. Very similar results were obtained when stimulating transient receptor potential

  12. Irradiance responsivity and unequivocal type-1 phase responsivity of rat circadian activity rhythms.

    PubMed

    Bauer, M S

    1992-11-01

    Behavioral, neuropharmacological, and molecular studies of light-induced phase shifting of rodent circadian rhythms evaluate carefully the phase dependence of light responsivity. However, much less information is available regarding the dependence of such effects on the duration and irradiance of the photic stimulus used. In this study, very brief (5-min) white light pulses of 50 microW/cm2 (175 lux) administered to hooded rats elicited unequivocal type-1 phase responsivity, without significant changes in period, and with phase shift variability comparable to that in studies using longer, higher intensity pulses. Irradiance dependence was demonstrated in the phase-delay, phase-advance, and crossover portions of the phase-response curve, with minimal phase shifting seen during the dead zone even at very high irradiance. These results indicate that maximal phase-shifting magnitude may be achieved with shorter, less intense photic stimuli than are often used in studies of the neural mechanisms involved in light responsivity of rat circadian rhythms. PMID:1443229

  13. Toward a Fast-Response Active Turbine Tip Clearance Control

    NASA Technical Reports Server (NTRS)

    Melcher, Kevin J.; Kypuros, Javier A.

    2003-01-01

    This paper describes active tip clearance control research being conducted by NASA to improve turbine engine systems. The target application for this effort is commercial aircraft engines. However, technologies developed for clearance control can benefit a broad spectrum of current and future turbomachinery. The first portion of the paper addresses the research from a programmatic viewpoint. Recent studies that provide motivation for the work, identification of key technologies, and NASA's plan for addressing deficiencies in the technologies are discussed. The later portion of the paper drills down into one of the key technologies by presenting equations and results for a preliminary dynamic model of the tip clearance phenomena.

  14. Role of protease-activated receptors for the innate immune response of the heart.

    PubMed

    Weithauser, Alice; Rauch, Ursula

    2014-08-01

    Protease-activated receptors (PARs) are a family of G-protein-coupled receptors with a unique activation mechanism via cleavage by the serine proteases of the coagulation cascade, immune cell-released proteases, and proteases from pathogens. Pathogens, such as viruses and bacteria, cause myocarditis and heart failure and PAR1 was shown to positively regulate the anti-viral innate immune response via interferon ? during virus-induced myocarditis. In contrast, PAR2 negatively regulated the innate immune response and inhibited the interferon ? expression. Thus, PARs play a central role for the innate immune response in the heart. PMID:25066486

  15. Activities of antioxidant enzymes and photosynthetic responses in tomato pre-treated by plant activators and inoculated by Xanthomonas vesicatoria

    Microsoft Academic Search

    Fabio Rossi Cavalcanti; Mario Lucio Vilela Resende; João Paulo Matos Santos Lima; Joaquim Albenisio Gomes Silveira; José Tadeu Abreu Oliveira

    2006-01-01

    The activities of antioxidant enzymes and photosynthetic responses were investigated in tomato (Lycopersicon esculentum L. var.) pre-treated by plant activators and inoculated by Xanthomonas vesicatoria. Plants were sprayed with acibenzolar-S-methyl, ASM [Bion® 50WG (0.2gl?1)] and aqueous extract from dry necrotic tissue flour (VLA) of ‘Lobeira’ (Solanum lycocarpum) bush. Four days later, the plants were challenged with a virulent strain of

  16. Orosomucoid, an acute response protein with multiple modulating activities.

    PubMed

    Luo, Zhumin; Lei, Hong; Sun, Yang; Liu, Xia; Su, Ding-Feng

    2015-06-01

    Orosomucoid (ORM), or alpha-1-acid glycoprotein (AGP), is one of the acute-phase proteins. It has a molecular weight of 37-54 kDa, low pI of 2.8-3.8, and is heavily glycosylated (45 %). It is mainly synthesized by the liver, but many extrahepatic tissues have also been reported to produce ORM under myriad physiological and pathological conditions. Expression of the ORM gene is mainly controlled by a combination of the major regulatory mediators, such as glucocorticoids, interleukin (IL)-1, TNF-?, and IL-6. ORM has many activities including, but not limited to, acting as an acute-phase reactant and disease marker, modulating immunity, binding and carrying drugs, maintaining the barrier function of capillary, and mediating the sphingolipid metabolism. Its related receptor has been preliminarily explored in macrophages, neutrophils, and liver parenchymal cells, involving the membrane receptor CCR5, Siglect-5, and HBB, respectively. Additional activities of ORM such as regulating metabolism are currently being explored. Because of its regulation in liver diseases, cancer, and HIV, future ORM research is warranted. PMID:25711902

  17. Mycobacterium tuberculosis Activates Human Macrophage Peroxisome Proliferator-Activated Receptor ? Linking Mannose Receptor Recognition to Regulation of Immune Responses

    PubMed Central

    Rajaram, Murugesan V. S.; Brooks, Michelle N.; Morris, Jessica D.; Torrelles, Jordi B.; Azad, Abul K.; Schlesinger, Larry S.

    2010-01-01

    Mycobacterium tuberculosis enhances its survival in macrophages by suppressing immune responses in part through its complex cell wall structures. Peroxisome proliferator-activated receptor ? (PPAR?), a nuclear receptor superfamily member, is a transcriptional factor that regulates inflammation and has high expression in alternatively activated alveolar macrophages and macrophage-derived foam cells, both cell types relevant to tuberculosis pathogenesis. In this study, we show that virulent M. tuberculosis and its cell wall mannose-capped lipoarabinomannan induce PPAR? expression through a macrophage mannose receptor-dependent pathway. When activated, PPAR? promotes IL-8 and cyclooxygenase 2 expression, a process modulated by a PPAR? agonist or antagonist. Upstream, MAPK-p38 mediates cytosolic phospholipase A2 activation, which is required for PPAR? ligand production. The induced IL-8 response mediated by mannose-capped lipoarabinomannan and the mannose receptor is independent of TLR2 and NF-?B activation. In contrast, the attenuated Mycobacterium bovis bacillus Calmette-Guérin induces less PPAR? and preferentially uses the NF-?B–mediated pathway to induce IL-8 production. Finally, PPAR? knockdown in human macrophages enhances TNF production and controls the intracellular growth of M. tuberculosis. These data identify a new molecular pathway that links engagement of the mannose receptor, an important pattern recognition receptor for M. tuberculosis, with PPAR? activation, which regulates the macrophage inflammatory response, thereby playing a role in tuberculosis pathogenesis. PMID:20554962

  18. Lags in Training Response to Changes in Economic Activity: An Exploratory Inquiry for Five Industries

    ERIC Educational Resources Information Center

    Azevedo, Ross E.; Park, Jin S.; Akdere, Mesut

    2007-01-01

    This study investigates the length of time it takes training budgets in five industries to respond to changes in the demand for their services/activity and for their speed of response to changes in productive activity. The results indicate that for the industries studied, the length of lag between change in demand and median adjustment to that…

  19. Cognitive Bias Modification: The Critical Role of Active Training in Modifying Emotional Responses

    Microsoft Academic Search

    Laura Hoppitt; Andrew Mathews; Jenny Yiend; Bundy Mackintosh

    2010-01-01

    Training participants to select threat or nonthreat interpretations of emotionally ambiguous stimuli or passively exposing them to valenced scenarios can modify later interpretation of ambiguity. However, only when encouraged to actively select meanings do congruent changes in emotional response occur during training itself (Mathews & Mackintosh, 2000). The present study assessed the more critical question of whether active training is

  20. The hemodynamic and arterial blood gas response to asphyxiation: a canine model of pulseless electrical activity

    Microsoft Academic Search

    Daniel J. DeBehnke; Swen J. Hilander; Daniel W. Dobler; Laurie L. Wickman; Gary L. Swart

    1995-01-01

    Objective: Asphyxiation is a time-honored animal model for producing pulseless electrical activity cardiac arrest. To date, there has not been a detailed description of the hemodynamic and arterial blood gas response to asphyxiation in a large number of animals. Our objective was to describe a single laboratory's experience with a standardized canine model of asphyxial pulseless electrical activity arrest. Methods:

  1. 7000 years of paleostorm activity in the NW Mediterranean Sea in response to Holocene climate events

    E-print Network

    Demouchy, Sylvie

    7000 years of paleostorm activity in the NW Mediterranean Sea in response to Holocene climate 2010 Available online 20 October 2011 Keywords: Paleostorms Mediterranean Sea Holocene Lagoon for high storm activity in the NW Mediterranean Sea is in agreement with the changes in coast- al

  2. A Feedback Model Reproduces Muscle Activity During Human Postural Responses to Support-Surface Translations

    E-print Network

    of human postural control have reproduced joint torques and segmental motions of the body, but not muscleReport A Feedback Model Reproduces Muscle Activity During Human Postural Responses to Support motions in human postural control, it is not known whether muscle activation patterns generated

  3. Gamma Band Unit Activity and Population Responses in the Pedunculopontine Nucleus

    PubMed Central

    Simon, Christen; Kezunovic, Nebojsa; Ye, Meijun; Hyde, James; Hayar, A.; Williams, D. K.

    2010-01-01

    The pedunculopontine nucleus (PPN) is involved in the activated states of waking and paradoxical sleep, forming part of the reticular activating system (RAS). The studies described tested the hypothesis that single unit and/or population responses of PPN neurons are capable of generating gamma band frequency activity. Whole cell patch clamp recordings (immersion chamber) and population responses (interface chamber) were conducted on 9- to 20-day-old rat brain stem slices. Regardless of cell type (I, II, or III) or type of response to the nonselective cholinergic receptor agonist carbachol (excitation, inhibition, biphasic), almost all PPN neurons fired at gamma band frequency, but no higher, when subjected to depolarizing steps (50 ± 2 Hz, mean ± SE). Nonaccommodating neurons fired at 18–100 Hz throughout depolarizing steps, while most accommodating neurons exhibited gamma band frequency of action potentials followed by gamma band membrane oscillations. These oscillations were blocked by the sodium channel blocker tetrodotoxin (TTX), suggesting that at least some are mediated by sodium currents. Population responses in the PPN showed that carbachol induced peaks of activation in the theta and gamma range, while glutamatergic receptor agonists induced overall increases in activity at theta and gamma frequencies, although in differing patterns. Gamma band activity appears to be a part of the intrinsic membrane properties of PPN neurons, and the population as a whole generates different patterns of gamma band activity under the influence of specific transmitters. Given sufficient excitation, the PPN may impart gamma band activation on its targets. PMID:20463196

  4. Asc and Ipaf Inflammasomes Direct Distinct Pathways for Caspase1 Activation in Response to Legionella pneumophila

    Microsoft Academic Search

    Christopher L. Case; Sunny Shin; Craig R. Roy

    2009-01-01

    Caspase-1 activation is a key feature of the innate immune response of macrophages elicited by pathogens and a variety of toxins. Here, we determined the requirement for different adapter proteins involved in regulating host processes mediated by caspase-1 after macrophage infection by Legionella pneumophila. The adapter protein Asc was found to be important for caspase-1 activation during L. pneumophila infection.

  5. A new biomimetic route to engineer enzymatically active mechano-responsive materials.

    PubMed

    Rios, César; Longo, Johan; Zahouani, Sarah; Garnier, Tony; Vogt, Cédric; Reisch, Andreas; Senger, Bernard; Boulmedais, Fouzia; Hemmerlé, Joseph; Benmlih, Karim; Frisch, Benoît; Schaaf, Pierre; Jierry, Loïc; Lavalle, Philippe

    2015-04-01

    Using modified ?-galactosidase covalently linked to cross-linked polyelectrolyte multilayers (PEM), catalytically active materials have been designed. Their enzymatic activity can be modulated, partially in a reversible way, simply by stretching. This strategy, based on enzyme conformational changes, constitutes a new tool for the development of biocatalytic mechano-responsive materials. PMID:25719225

  6. Cortical Activity during Manual Response Inhibition Guided by Color and Orientation Cues

    PubMed Central

    Cai, Weidong; Leung, Hoi-Chung

    2009-01-01

    It has been suggested that the right inferior frontal gyrus (IFG) plays a critical role in manual response inhibition, although neuroimaging studies of healthy adults have also reported widespread activations in other cortical regions during a variety of response inhibition tasks. We conducted a functional magnetic resonance imaging (fMRI) experiment to examine whether the activation of the IFG is dependent on the type of visuo-motor associations during response inhibition by varying the feature of the stop signal (color vs. orientation) in the stop-signal task. Results from 12 subjects showed that the bilateral ventral posterior IFG, anterior insula, inferior frontal junction (IFJ), middle temporal gyrus (MTG) and fusiform gyrus (FG) are active during response inhibition cued by both color and orientation stop signals. While only the MTG showed differential activity to the two stop signals, both MTG and FG showed significantly stronger activity during successful than unsuccessful stopping of unwanted responses cued by orientation and color, respectively. Our findings suggest that the right ventral posterior IFG may play a more general role in response inhibition regardless of the feature of the visual signal, while successful inhibition may depend on efficient processing of the signal. PMID:19401178

  7. Activation of stress-responsive mitogen-activated protein kinase pathways in hybrid poplar (Populus trichocarpa x Populus deltoides).

    PubMed

    Hamel, Louis-Philippe; Miles, Godfrey P; Samuel, Marcus A; Ellis, Brian E; Séguin, Armand; Beaudoin, Nathalie

    2005-03-01

    Plant mitogen-activated protein kinase (MAPK) cascades are important amplifying modules that can rapidly transduce stress signals into various appropriate intracellular responses. Several extracellular regulated kinase (ERK)-type MAPKs involved in plant defense signaling have been identified in herbaceous species, but no MAPK cascade has yet been characterized in a tree species. We examined the signal transduction events that lead to activation of defense mechanisms in poplar, a major forest species of economic and ecological importance which is becoming the model tree system for studying stress and adaptation responses. We show that, in poplar cell suspensions and leaf tissue, chitosan, a non-host-specific elicitor, and ozone, a strong oxidant and atmospheric pollutant, induce rapid and transient activation of at least two myelin basic protein (MBP) kinases with apparent molecular masses of 44 and 47 kD. The chitosan- and ozone-activated kinases have characteristics of MAPKs-they preferentially phosphorylate MBP, require tyrosine and threonine phosphorylation to be activated and are specifically recognized by anti-ERK and anti-pERK antibodies. Moreover, activation of these poplar MAPKs by chitosan or ozone is dependent on the production of reactive oxygen species; the influx of calcium ions via membrane channels; the activation of an upstream, membrane-localized component; and a cognate MAPK kinase (MAPKK). These data suggest that biotic and abiotic challenges activate MAPKs in poplar, as in herbaceous species, which then function as a convergence point for pathogen defense and oxidant stress signaling cascades. PMID:15631976

  8. Duration differences of corticostriatal responses in striatal projection neurons depend on calcium activated potassium currents

    PubMed Central

    Arias-García, Mario A.; Tapia, Dagoberto; Flores-Barrera, Edén; Pérez-Ortega, Jesús E.; Bargas, José; Galarraga, Elvira

    2013-01-01

    The firing of striatal projection neurons (SPNs) exhibits afterhyperpolarizing potentials (AHPs) that determine discharge frequency. They are in part generated by Ca2+-activated K+-currents involving BK and SK components. It has previously been shown that suprathreshold corticostriatal responses are more prolonged and evoke more action potentials in direct pathway SPNs (dSPNs) than in indirect pathway SPNs (iSPNs). In contrast, iSPNs generate dendritic autoregenerative responses. Using whole cell recordings in brain slices, we asked whether the participation of Ca2+-activated K+-currents plays a role in these responses. Secondly, we asked if these currents may explain some differences in synaptic integration between dSPNs and iSPNs. Neurons obtained from BAC D1 and D2 GFP mice were recorded. We used charybdotoxin and apamin to block BK and SK channels, respectively. Both antagonists increased the depolarization and delayed the repolarization of suprathreshold corticostriatal responses in both neuron classes. We also used NS 1619 and NS 309 (CyPPA), to enhance BK and SK channels, respectively. Current enhancers hyperpolarized and accelerated the repolarization of corticostriatal responses in both neuron classes. Nevertheless, these drugs made evident that the contribution of Ca2+-activated K+-currents was different in dSPNs as compared to iSPNs: in dSPNs their activation was slower as though calcium took a diffusion delay to activate them. In contrast, their activation was fast and then sustained in iSPNs as though calcium flux activates them at the moment of entry. The blockade of Ca2+-activated K+-currents made iSPNs to look as dSPNs. Conversely, their enhancement made dSPNs to look as iSPNs. It is concluded that Ca2+-activated K+-currents are a main intrinsic determinant causing the differences in synaptic integration between corticostriatal polysynaptic responses between dSPNs and iSPNs. PMID:24109439

  9. Activation and manipulation of host responses by a Gram-positive bacterium.

    PubMed

    Balaji, Vasudevan; Sessa, Guido

    2008-10-01

    The interaction between tomato plants and Clavibacter michiganensis subsp. michiganensis (Cmm) represents a model pathosystem to study the interplay between the virulence determinants of a Gram-positive bacterium and the attempt of a crop plant to counteract pathogen invasion. To investigate plant responses activated during this compatible interaction, we recently analyzed gene expression profiles of tomato stems infected with Cmm. This analysis revealed activation of basal defense responses that are typically observed upon plant perception of pathogen-associated molecular patterns. In addition, Cmm infection upregulated the expression of host genes related to ethylene synthesis and response. Further analysis of tomato plants impaired in ethylene perception and production demonstrated an important role for ethylene in the development of disease symptoms. Here we discuss possible molecular strategies used by the plant to recognize Cmm infection and possible mechanisms employed by the pathogen to interfere with the activation of plant defense responses and promote disease. PMID:19704516

  10. Activation of Endoplasmic Reticulum Stress Response Following Trauma-Hemorrhage

    PubMed Central

    Jian, Bixi; Hsieh, Chi-Hsun; Chen, Jianguo; Choudhry, Mashkoor; Bland, Kirby; Chaudry, Irshad; Raju, Raghavan

    2008-01-01

    Summary Hemorrhagic trauma leads to organ dysfunction, sepsis and death. There is abnormal production of proinflammatory cytokines by Kupffer cells, tissue hypoxia and liver injury following trauma-hemorrhage. The physiological conditions consequent to trauma-hemorrhage are consistent with factors necessary to initiate endoplasmic reticulum (ER) stress and unfolded protein response. However, the contribution of ER stress to apoptosis and liver injury after trauma-hemorrhage is not known. In the present study ER stress was investigated in mice that underwent trauma-hemorrhage or sham operation. Expression of endoplasmic reticulum stress proteins Bip, ATF6, PERK, IRE1?, and PDI were significantly elevated in the liver after trauma-hemorrhage compared to the controls. The ER stress associated proapoptotic transcription factor CHOP protein expression was also significantly elevated in trauma-hemorrhage group. Consistent with this, enhanced DNA fragmentation was observed, confirming apoptosis, in the liver following trauma-hemorrhage. These results demonstrate the initiation of ER stress and its role in apoptosis and liver injury, subsequent to hemorrhagic trauma. PMID:18801427

  11. Geomagnetic responses to the solar wind and to solar activity

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1974-01-01

    A unified overview of present knowledge of the geomagnetic response to the dynamic solar wind is reported. The formation of the magnetosphere and the magnetospheric tail is discussed the importance of electric fields is stressed, and the magnetospheric convection of plasma and frozen-in magnetic field lines under the influence of large scale magnetospheric electric fields is outlined. Ionospheric electric fields and currents are intimately related to electric fields and currents in the magnetosphere and the strong coupling between the two regions is discussed. The energy input of the solar wind to the magnetosphere and upper atmosphere is discussed in terms of the reconnection model where interplanetary magnetic field lines merge or connect with the terrestrial field on the sunward side of the magnetosphere. The merging model emphasizes the importance of the interplanetary magnetic field and especially the north-south component. The solar sector structure with its organized magnetic field and embeeded high speed plasma streams is identified as the source of recurrent geomagnetic disturbances while flare associated interplanetary shock waves are the source of most violet and sporadic geomagnetic storms.

  12. Active immunotherapy induces antibody responses that target tumor angiogenesis.

    PubMed

    Schoenfeld, Jonathan; Jinushi, Masahisa; Nakazaki, Yukoh; Wiener, Daniel; Park, Joosang; Soiffer, Robert; Neuberg, Donna; Mihm, Martin; Hodi, F Stephen; Dranoff, Glenn

    2010-12-15

    The inhibition of VEGF signaling with antibodies or small molecules achieves clinical benefits in diverse solid malignancies. Nonetheless, therapeutic effects are usually not sustained, and most patients eventually succumb to progressive disease, indicating that antiangiogenic strategies require additional optimization. Vaccination with lethally irradiated, autologous tumor cells engineered to secrete granulocyte-macrophage colony stimulating factor (GM-CSF) and antibody blockade of cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) trigger a tumor vasculopathy in some long-term responding subjects. These reactions are characterized by disrupted tumor blood vessels in association with lymphocyte and granulocyte infiltrates and zonal areas of ischemic tumor necrosis. However, the mechanisms underlying this immune-mediated destruction of the tumor vasculature remain to be clarified. Here, we show that GM-CSF-secreting tumor cell vaccines and CTLA-4 blockade elicit a functionally important humoral reaction against multiple angiogenic cytokines. Antibodies to angiopoietin-1 and angiopoietin-2 block Tie-2 binding, downstream signaling, endothelial cell tube formation, and macrophage chemotaxis. Antibodies to macrophage inhibitory factor (MIF) attenuate macrophage Tie-2 expression and matrix metalloproteinase-9 (MMP-9) production. Together, these results delineate an immunotherapy-induced host response that broadly targets the angiogenic network in the tumor microenvironment. PMID:21159637

  13. Mining large-scale response networks reveals ‘topmost activities’ in Mycobacterium tuberculosis infection

    PubMed Central

    Sambarey, Awanti; Prashanthi, Karyala; Chandra, Nagasuma

    2013-01-01

    Mycobacterium tuberculosis owes its high pathogenic potential to its ability to evade host immune responses and thrive inside the macrophage. The outcome of infection is largely determined by the cellular response comprising a multitude of molecular events. The complexity and inter-relatedness in the processes makes it essential to adopt systems approaches to study them. In this work, we construct a comprehensive network of infection-related processes in a human macrophage comprising 1888 proteins and 14,016 interactions. We then compute response networks based on available gene expression profiles corresponding to states of health, disease and drug treatment. We use a novel formulation for mining response networks that has led to identifying highest activities in the cell. Highest activity paths provide mechanistic insights into pathogenesis and response to treatment. The approach used here serves as a generic framework for mining dynamic changes in genome-scale protein interaction networks. PMID:23892477

  14. Mid-latitude ionospheric response to active experiments

    NASA Technical Reports Server (NTRS)

    Foster, John C.

    1992-01-01

    Understanding the ion chemistry and conditions leading to the formation of ionospheric depletions (ionospheric holes) was an important objective of the NASA active ionospheric experiment program. Millstone Hill radar observations were used to monitor the magnitude and temporal extent of the plasma holes produced under varying conditions. The major objective of the completed project was to provide radar diagnostic support for individual NASA rocket campaigns flown from Wallops Island. Two rocket programs, NICARE and REDAIR 2, were selected by NASA for radar support during the proposal period and pre-launch and in-flight radar observations were provided for each as well as basic reduction of the acquired data for scientific analysis. Radar operations and analysis for both of these experiments were performed as proposed and the work on these projects at M.I.T. was completed.

  15. Medial prefrontal cortex activity can disrupt the expression of stress response habituation

    PubMed Central

    Weinberg, Marc S.; Johnson, Drew C.; Bhatt, Aadra P.; Spencer, Robert L.

    2010-01-01

    Recent findings suggest that the expression of hypothalamic-pituitary-adrenal (HPA) axis stress response adaptation in rats depends on top-down neural control. We therefore examined whether the medial prefrontal cortex (mPFC) modulates expression of stress response habituation. We transiently suppressed (muscimol microinfusion) or stimulated (picrotoxin microinfusion) mPFC neural activity in rats and studied the consequence on the first time response to psychological stress (restraint) or separately on the development and expression of habituation to repeated restraint. We monitored both the hormonal (corticosterone) and neural (forebrain c-fos mRNA) response to stress. Inactivation of the mPFC had no effect on the HPA-axis response to first time restraint, however increased mPFC activity attenuated stress-induced HPA-axis activity. In a three day repeated restraint stress regimen, inactivation of the mPFC on days 1 and 2, but not day 3, prevented the expression of HPA-axis hormone response habituation. In these same rats, the mPFC activity on day 3 interfered with the expression of c-fos mRNA habituation selectively within the mPFC, lateral septum and hypothalamic paraventricular nucleus. In contrast, inactivation of the mPFC only on day 3, or on all 3 days did not interfere with the expression of habituation. We conclude that the mPFC can permit or disrupt expression of HPA-axis stress response habituation, and this control depends on alteration of neural activity within select brain regions. A possible implication of these findings is that the dysregulation of PFC activity associated with depression and post-traumatic stress disorder may contribute to impaired expression of stress-response adaptation and consequently exacerbation of those disorders. PMID:20394807

  16. Interplay between the E2F pathway and ?-adrenergic signaling in the pathological hypertrophic response of myocardium.

    PubMed

    Major, Jennifer L; Salih, Maysoon; Tuana, Balwant S

    2015-07-01

    The E2F/Pocket protein (Rb) pathway regulates cell growth, differentiation, and death by modulating gene expression. We previously examined this pathway in the myocardium via manipulation of the unique E2F repressor, E2F6, which is believed to repress gene activity independently of Rb. Mice with targeted expression of E2F6 in postnatal myocardium developed dilated cardiomyopathy (DCM) without hypertrophic growth. We assessed the mechanisms of the apparent failure of compensatory hypertrophic growth as well as their response to the ?-adrenergic agonist isoproterenol. As early as 2weeks, E2F6 transgenic (Tg) mice present with dilated thinner left ventricles and significantly reduced ejection fraction and fractional shortening which persists at 6weeks of age, but with no apparent increase in left ventricle weight: body weight (LVW:BW). E2F6-Tg mice treated with isoproterenol (6.1mg/kg/day) show double the increase in LVW:BW than their Wt counterparts (32% vs 16%, p-value: 0.007). Western blot analysis revealed the activation of the adrenergic pathway in Tg heart tissue under basal conditions with ~2-fold increase in the level of ?2-adrenergic receptors (p-value: 8.9E-05), protein kinase A catalytic subunit (PKA-C) (p-value: 0.0176), activated c-Src tyrosine-protein kinase (p-value: 0.0002), extracellular receptor kinase 2 (ERK2) (p-value: 0.0005), and induction of the anti-apoptotic protein Bcl2 (p-value 0. 0.00001). In contrast, a ~60% decrease in the cardiac growth regulator: AKT1 (p-value 0.0001) and a ~four fold increase in cyclic AMP dependent phosphodiesterase 4D (PDE4D), the negative regulator of PKA activity, were evident in the myocardium of E2F6-Tg mice. The expression of E2F3 was down-regulated by E2F6, but was restored by isoproterenol. Further, Rb expression was down-regulated in Tg mice in response to isoproterenol implying a net activation of the E2F pathway. Thus the unique regulation of E2F activity by E2F6 renders the myocardium hypersensitive to adrenergic stimulus resulting in robust hypertrophic growth. These data reveal a novel interplay between the E2F pathway, ?2-adrenergic/PKA/PDE4D, and ERK/c-Src axis in fine tuning the pathological hypertrophic growth response. E2F6 deregulates E2F3 such that pro-hypertrophic growth and survival are enhanced via ?2-adrenergic signaling however this response is outweighed by the induction of anti-hypertrophic signals so that left ventricle dilation proceeds without any increase in muscle mass. PMID:25944088

  17. Activism and Leadership Development: Examining the Relationship between College Student Activism Involvement and Socially Responsible Leadership Capacity

    ERIC Educational Resources Information Center

    Page, Jeremy Dale

    2010-01-01

    The purpose of this study was to examine the relationship between participation in student activism and leadership development among college students. This study applied the social change model of leadership development (SCM) as the theoretical model used to measure socially responsible leadership capacity in students. The study utilized data…

  18. Dissociable patterns of neural activity during response inhibition in depressed adolescents with and without suicidal behavior

    PubMed Central

    Pan, Lisa A.; Batezati-Alves, Silvia C.; Almeida, Jorge R.C.; Segreti, AnnaMaria; Akkal, Dalila; Hassel, Stefanie; Lakdawala, Sara; Brent, David A.; Phillips, Mary L.

    2011-01-01

    Objectives Impaired attentional control and behavioral control are implicated in adult suicidal behavior. Little is known about the functional integrity of neural circuitry supporting these processes in suicidal behavior in adolescence. Method We employed fMRI in 15 adolescent suicide attempters with history of major depressive disorder (MDD; ATT), 15 adolescents with history of MDD but not suicide attempt (NAT), and 14 healthy controls (HC), during performance of a well-validated GoNoGo response inhibition and motor control task that measures attentional and behavioral control, and has been shown to activate prefrontal, anterior cingulate and parietal cortical circuitry. Questionnaires assessed symptoms and standardized interviews characterized suicide attempt. Results A 3 group × 2 condition (“GoNoGo” response inhibition versus “Go” motor control blocks) block-design whole-brain analysis (p<0.05, corrected) revealed that NAT showed greater activity than ATT in right anterior cingulate gyrus (p=0.008), and that NAT, but not ATT, showed significantly greater activity than HC in the left insula (p=0.004) to GoNoGo response inhibition blocks. Conclusions While ATT did not show differential patterns of neural activity from HC during GoNoGo response inhibition blocks, ATT and NAT showed differential activation of the right anterior cingulate gyrus during response inhibition. Our findings indicate that suicide attempt during adolescence is not associated with abnormal activity in response inhibition neural circuitry. The differential patterns of activity in response inhibition neural circuitry in ATT and NAT, however, suggest different neural mechanisms for suicide attempt versus MDD in general in adolescence that should be a focus of further study. PMID:21621144

  19. Alterations in serum lipolytic activity of cancer patients with response to therapy.

    PubMed Central

    Beck, S. A.; Groundwater, P.; Barton, C.; Tisdale, M. J.

    1990-01-01

    The effect of chemotherapy on the serum lipid mobilising activity of a group of cancer patients with or without weight loss has been determined. The pre-treatment level of serum lipolytic activity in all cancer patients, with or without weight loss, was higher than normal controls (0.22 +/- 0.01 versus 0.06 +/- 0.01 mumols glycerol released ml-1 serum respectively). The pre-treatment levels of lipid mobilising activity in the patients serum was proportional to the extent of weight loss (correlation coefficient 0.81), if the extent of weight loss was small (less than 14 kg). Patients who showed a positive response to chemotherapy also showed a decrease in their plasma levels of lipolytic activity, while a patient who showed no response to therapy also showed no change in the serum lipolytic activity. There was no correlation between the serum lipolytic activity and response to megestrol acetate, a synthetic orally active progestogen, which is currently under investigation as an anticachectic agent. Serum from cancer patients showed lipolytic activity which was retained on a DEAE cellulose column and eluted by a salt gradient, in contrast with normal controls. Response to chemotherapy was associated with a decrease of the retained material, although the profile did not return to the normal state. These results need confirmation in a larger group of patients using more specific methods to determine tumour lipolytic activity, but suggest that it may be possible to monitor response to therapy by measurement of the serum lipolytic activity. PMID:2245174

  20. Identification of a Neuropeptide S Responsive Circuitry Shaping Amygdala Activity via the Endopiriform Nucleus

    PubMed Central

    Meis, Susanne; Bergado-Acosta, Jorge Ricardo; Yanagawa, Yuchio; Obata, Kunihiko; Stork, Oliver; Munsch, Thomas

    2008-01-01

    Neuropeptide S (NPS) and its receptor are thought to define a set of specific brain circuits involved in fear and anxiety. Here we provide evidence for a novel, NPS-responsive circuit that shapes neural activity in the mouse basolateral amygdala (BLA) via the endopiriform nucleus (EPN). Using slice preparations, we demonstrate that NPS directly activates an inward current in 20% of EPN neurons and evokes an increase of glutamatergic excitation in this nucleus. Excitation of the EPN is responsible for a modulation of BLA activity through NPS, characterized by a general increase of GABAergic inhibition and enhancement of spike activity in a subset of BLA projection neurons. Finally, local injection of NPS to the EPN interferes with the expression of contextual, but not auditory cued fear memory. Together, these data suggest the existence of a specific NPS-responsive circuitry between EPN and BLA, likely involved in contextual aspects of fear memory. PMID:18628994

  1. Watch out! Medial frontal cortex is activated by cues signaling potential changes in response demands.

    PubMed

    van Noordt, Stefon J R; Desjardins, James A; Segalowitz, Sidney J

    2015-07-01

    The human medial frontal cortex and especially the anterior cingulate cortex (ACC) have been implicated in several aspects of performance monitoring. We examined event-related EEG during a general process of controlling attention by using a novel paradigm to elicit a medial frontal negativity (MFN) to stimuli that indicate potential changes in future response demands. Independent components analysis revealed that the latent factors that accounted for MFN activity to such changes also accounted for activity associated with the error-related negativity and the NoGo inhibitory N2. Given that the medial frontal activation to these changes varied reliably across subjects simply as a function of potential need to alter responses in the absence of error commission and response inhibition, we propose that the underlying basis for medial frontal activation in situations demanding ongoing monitoring of performance involves an increase in attention control, a factor common to all MFN paradigms. PMID:25887260

  2. Sensory integration and response to balance perturbation in overweight physically active individuals.

    PubMed

    Cheung, Peggy Py; Azevedo, Liane B

    2015-01-01

    The purpose of this study was to compare sensory integration and response to balance perturbation between physically active normal weight and overweight adults. Physically active young adults were grouped into normal weight (n = 45) or overweight (n = 17) according to the World Health Organization body mass index classification for Asian adults. Participants underwent two balance tests: sensory organization and motor control. Overweight participants presented marginally lower somatosensory score compared to normal weight participants. However, they scored significantly higher in response to balance perturbation. There was no difference in the onset of participants' active response to balance perturbation. Physical activity might have contributed to improved muscle strength and improved the ability of overweight individuals to maintain balance. PMID:25738978

  3. Activation of cutaneous immune responses in complex regional pain syndrome

    PubMed Central

    Birklein, Frank; Drummond, Peter D.; Li, Wenwu; Schlereth, Tanja; Albrecht, Nahid; Finch, Philip M.; Dawson, Linda F.; Clark, J. David; Kingery, Wade S.

    2014-01-01

    The pathogenesis of complex regional pain syndrome (CRPS) is unresolved, but TNF-? and IL-6 are elevated in experimental skin blister fluid from CRPS affected limbs, as is tryptase, a marker for mast cells. In the rat fracture model of CRPS exaggerated sensory and sympathetic neural signaling stimulate keratinocyte and mast cell proliferation, causing the local production of high levels of inflammatory cytokines leading to pain behavior. The current investigation used CRPS patient skin biopsies to determine whether keratinocyte and mast cell proliferation occur in CRPS skin and to identify the cellular source of the up-regulated TNF-?, IL-6, and tryptase observed in CRPS experimental skin blister fluid. Skin biopsies were collected from the affected skin and the contralateral mirror site in 55 CRPS patients and the biopsy sections were immunostained for keratinocyte, cell proliferation, mast cell markers, TNF-?, and IL-6. In early CRPS keratinocytes were activated in the affected skin, resulting in proliferation, epidermal thickening, and up-regulated TNF-? and IL-6 expression. In chronic CRPS there was reduced keratinocyte proliferation with epidermal thinning in the affected skin. Acute CRPS patients also had increased mast cell accumulation in the affected skin, but there was no increase in mast cell numbers in chronic CRPS. PMID:24462502

  4. Global changes in biogeochemical cycles in response to human activities

    NASA Technical Reports Server (NTRS)

    Moore, Berrien, III; Melillo, Jerry

    1994-01-01

    The main objective of our research was to characterize biogeochemical cycles at continental and global scales in both terrestrial and aquatic ecosystems. This characterization applied to both natural ecosystems and those disturbed by human activity. The primary elements of interest were carbon and nitrogen and the analysis sought to quantify standing stocks and dynamic cycling processes. The translocation of major nutrients from the terrestrial landscape to the atmosphere (via trace gases) and to fluvial systems (via leaching, erosional losses, and point source pollution) were of particular importance to this study. Our aim was to develop the first generation of Earth System Models. Our research was organized around the construction and testing of component biogeochemical models which treated terrestrial ecosystem processes, aquatic nutrient transport through drainage basins, and trace gas exchanges at the continental and global scale. A suite of three complementary models were defined within this construct. The models were organized to operate at a 1/2 degree latitude by longitude level of spatial resolution and to execute at a monthly time step. This discretization afforded us the opportunity to understand the dynamics of the biosphere down to subregional scales, while simultaneously placing these dynamics into a global context.

  5. Key residues on microtubule responsible for activation of kinesin ATPase

    PubMed Central

    Uchimura, Seiichi; Oguchi, Yusuke; Hachikubo, You; Ishiwata, Shin'ichi; Muto, Etsuko

    2010-01-01

    Microtubule (MT) binding accelerates the rate of ATP hydrolysis in kinesin. To understand the underlying mechanism, using charged-to-alanine mutational analysis, we identified two independent sites in tubulin, which are critical for kinesin motility, namely, a cluster of negatively charged residues spanning the helix 11–12 (H11–12) loop and H12 of ?-tubulin, and the negatively charged residues in H12 of ?-tubulin. Mutation in the ?-tubulin-binding site results in a deceleration of ATP hydrolysis (kcat), whereas mutation in the ?-tubulin-binding site lowers the affinity for MTs (K0.5MT). The residue E415 in ?-tubulin seems to be important for coupling MT binding and ATPase activation, because the mutation at this site results in a drastic reduction in the overall rate of ATP hydrolysis, largely due to a deceleration in the reaction of ADP release. Our results suggest that kinesin binding at a region containing ?-E415 could transmit a signal to the kinesin nucleotide pocket, triggering its conformational change and leading to the release of ADP. PMID:20224548

  6. Efficient Modeling and Active Learning Discovery of Biological Responses

    PubMed Central

    Naik, Armaghan W.; Kangas, Joshua D.; Langmead, Christopher J.; Murphy, Robert F.

    2013-01-01

    High throughput and high content screening involve determination of the effect of many compounds on a given target. As currently practiced, screening for each new target typically makes little use of information from screens of prior targets. Further, choices of compounds to advance to drug development are made without significant screening against off-target effects. The overall drug development process could be made more effective, as well as less expensive and time consuming, if potential effects of all compounds on all possible targets could be considered, yet the cost of such full experimentation would be prohibitive. In this paper, we describe a potential solution: probabilistic models that can be used to predict results for unmeasured combinations, and active learning algorithms for efficiently selecting which experiments to perform in order to build those models and determining when to stop. Using simulated and experimental data, we show that our approaches can produce powerful predictive models without exhaustive experimentation and can learn them much faster than by selecting experiments at random. PMID:24358322

  7. Constitutively expressed ERF-VII transcription factors redundantly activate the core anaerobic response in Arabidopsis thaliana.

    PubMed

    Bui, Liem T; Giuntoli, Beatrice; Kosmacz, Monika; Parlanti, Sandro; Licausi, Francesco

    2015-07-01

    Plant adaptation to hypoxic conditions is mediated by the transcriptional activation of genes involved in the metabolic reprogramming of plant cells to cope with reduced oxygen availability. Recent studies indicated that members of the group VII of the Ethylene Responsive Transcription Factor (ERFs) family act as positive regulators of this molecular response. In the current study, the five ERF-VII transcription factors of Arabidopsis thaliana were compared to infer a hierarchy in their role with respect to the anaerobic response. When the activity of each transcription factor was tested on a set of hypoxia-responsive promoters, RAP2.2, RAP2.3 and RAP2.12 appeared to be the most powerful activators. RAP2.12 was further dissected in transactivation assays in Arabidopsis protoplasts to identify responsible regions for transcriptional activation. An ultimate C-terminal motif was identified as sufficient to drive gene transcription. Finally, using realtime RT-PCR in single and double mutants for the corresponding genes, we confirmed that RAP2.2 and RAP2.12 exert major control upon the anaerobic response. PMID:26025519

  8. Rhythmic Auditory Cortex Activity at Multiple Timescales Shapes Stimulus–Response Gain and Background Firing

    PubMed Central

    Wilson, Caroline; Safaai, Houman; Sakata, Shuzo; Panzeri, Stefano

    2015-01-01

    The phase of low-frequency network activity in the auditory cortex captures changes in neural excitability, entrains to the temporal structure of natural sounds, and correlates with the perceptual performance in acoustic tasks. Although these observations suggest a causal link between network rhythms and perception, it remains unknown how precisely they affect the processes by which neural populations encode sounds. We addressed this question by analyzing neural responses in the auditory cortex of anesthetized rats using stimulus–response models. These models included a parametric dependence on the phase of local field potential rhythms in both stimulus-unrelated background activity and the stimulus–response transfer function. We found that phase-dependent models better reproduced the observed responses than static models, during both stimulation with a series of natural sounds and epochs of silence. This was attributable to two factors: (1) phase-dependent variations in background firing (most prominent for delta; 1–4 Hz); and (2) modulations of response gain that rhythmically amplify and attenuate the responses at specific phases of the rhythm (prominent for frequencies between 2 and 12 Hz). These results provide a quantitative characterization of how slow auditory cortical rhythms shape sound encoding and suggest a differential contribution of network activity at different timescales. In addition, they highlight a putative mechanism that may implement the selective amplification of appropriately timed sound tokens relative to the phase of rhythmic auditory cortex activity. PMID:25995464

  9. Activation of defense response pathways by OGs and Flg22 elicitors in Arabidopsis seedlings

    PubMed Central

    Denoux, Carine; Galletti, Roberta; Mammarella, Nicole; Gopalan, Suresh; Werck, Danièle; De Lorenzo, Giulia; Ferrari, Simone; Ausubel, Frederick M.; Dewdney, Julia

    2010-01-01

    We carried out transcriptional profiling analysis in 10 day-old Arabidopsis thaliana seedlings treated with oligogalacturonides (OGs), oligosaccharides derived from the plant cell wall, or the bacterial flagellin peptide Flg22, general elicitors of the basal defense response in plants. Although detected by different receptors, both OGs and Flg22 trigger a fast and transient response that is both similar and comprehensive, and characterized by activation of early stages of multiple defense signaling pathways, particularly JA-associated processes. However, the response to Flg22 is stronger in both the number of genes differentially expressed and the amplitude of change. The magnitude of induction of individual genes is in both cases dose dependent, but even at very high concentrations, OGs do not induce a response that is as comprehensive as that seen with Flg22. While high doses of either microbe-associated molecular pattern (MAMP) elicit a late response that includes activation of senescence processes, SA-dependent secretory pathway genes and PR1 expression are substantially induced only by Flg22. These results suggest a lower threshold for activation of early responses than for sustained or SA-mediated late defenses. Expression patterns of aminocyclopropane-carboxylate synthase genes also implicate ethylene biosynthesis in regulation of the late innate immune response. PMID:19825551

  10. Activation of the unfolded protein response during anoxia exposure in the turtle Trachemys scripta elegans.

    PubMed

    Krivoruchko, Anastasia; Storey, Kenneth B

    2013-02-01

    Red-eared slider turtles, Trachemys scripta elegans, can survive for several weeks without oxygen when submerged in cold water. We hypothesized that anaerobiosis is aided by adaptive up-regulation of the unfolded protein response (UPR), a stress-responsive pathway that is activated by accumulation of unfolded proteins in the endoplasmic reticulum (ER) and functions to restore ER homeostasis. RT-PCR, western immunoblotting and DNA-binding assays were used to quantify the responses and/or activation status of UPR-responsive genes and proteins in turtle tissues after animal exposure to 5 or 20 h of anoxic submergence at 4 °C. The phosphorylation state of protein kinase-like ER kinase (PERK) (a UPR-regulated kinase) and eukaryotic initiation factor 2 (eIF2?) increased by 1.43-2.50 fold in response to anoxia in turtle heart, kidney, and liver. Activation of the PERK-regulated transcription factor, activating transcription factor 4 (ATF4), during anoxia was documented by elevated atf4 transcripts and total ATF4 protein (1.60-2.43 fold), increased nuclear ATF4 content, and increased DNA-binding activity (1.44-2.32 fold). ATF3 and GADD34 (downstream targets of ATF4) also increased by 1.38-3.32 fold in heart and liver under anoxia, and atf3 transcripts were also elevated in heart. Two characteristic chaperones of the UPR, GRP78, and GRP94, also responded positively to anoxia with strong increases in both the transcript and protein levels. The data demonstrate that the UPR is activated in turtle heart, kidney, and liver in response to anoxia, suggesting that this pathway mediates an integrated stress response to protect tissues during oxygen deprivation. PMID:23124854

  11. Rapid response of a hydrologic system to volcanic activity: Masaya volcano, Nicaragua

    USGS Publications Warehouse

    Pearson, S.C.P.; Connor, C.B.; Sanford, W.E.

    2008-01-01

    Hydrologic systems change in response to volcanic activity, and in turn may be sensitive indicators of volcanic activity. Here we investigate the coupled nature of magmatic and hydrologic systems using continuous multichannel time series of soil temperature collected on the flanks of Masaya volcano, Nicaragua, one of the most active volcanoes in Central America. The soil temperatures were measured in a low-temperature fumarole field located 3.5 km down the flanks of the volcano. Analysis of these time series reveals that they respond extremely rapidly, on a time scale of minutes, to changes in volcanic activity also manifested at the summit vent. These rapid temperature changes are caused by increased flow of water vapor through flank fumaroles during volcanism. The soil temperature response, ~5 °C, is repetitive and complex, with as many as 13 pulses during a single volcanic episode. Analysis of the frequency spectrum of these temperature time series shows that these anomalies are characterized by broad frequency content during volcanic activity. They are thus easily distinguished from seasonal trends, diurnal variations, or individual rainfall events, which triggered rapid transient increases in temperature during 5% of events. We suggest that the mechanism responsible for the distinctive temperature signals is rapid change in pore pressure in response to magmatism, a response that can be enhanced by meteoric water infiltration. Monitoring of distal fumaroles can therefore provide insight into coupled volcanic-hydrologic-meteorologic systems, and has potential as an inexpensive monitoring tool.

  12. Statistical Analysis of Metal Chelating Activity of Centella asiatica and Erythroxylum cuneatum Using Response Surface Methodology.

    PubMed

    Mohd Salim, R J; Adenan, M I; Amid, A; Jauri, M H; Sued, A S

    2013-01-01

    The purpose of the study is to evaluate the relationship between the extraction parameters and the metal chelating activity of Centella asiatica (CA) and Erythroxylum cuneatum (EC). The response surface methodology was used to optimize the extraction parameters of methanolic extract of CA and EC with respect to the metal chelating activity. For CA, Run 17 gave optimum chelating activity with IC50 = 0.93?mg/mL at an extraction temperature of 25°C, speed of agitation at 200?rpm, ratio of plant material to solvent at 1?g?:?45?mL and extraction time at 1.5 hour. As for EC, Run 13 with 60°C, 200?rpm, 1?g?:?35?mL and 1 hour had metal chelating activity at IC50 = 0.3817?mg/mL. Both optimized extracts were further partitioned using a solvent system to evaluate the fraction responsible for the chelating activity of the plants. The hexane fraction of CA showed potential activity with chelating activity at IC50 = 0.090 and the ethyl acetate fraction of EC had IC50 = 0.120?mg/mL. The study showed that the response surface methodology helped to reduce the extraction time, temperature and agitation and subsequently improve the chelating activity of the plants in comparison to the conventional method. PMID:23533781

  13. Statistical Analysis of Metal Chelating Activity of Centella asiatica and Erythroxylum cuneatum Using Response Surface Methodology

    PubMed Central

    Mohd Salim, R. J.; Adenan, M. I.; Amid, A.; Jauri, M. H.; Sued, A. S.

    2013-01-01

    The purpose of the study is to evaluate the relationship between the extraction parameters and the metal chelating activity of Centella asiatica (CA) and Erythroxylum cuneatum (EC). The response surface methodology was used to optimize the extraction parameters of methanolic extract of CA and EC with respect to the metal chelating activity. For CA, Run 17 gave optimum chelating activity with IC50 = 0.93?mg/mL at an extraction temperature of 25°C, speed of agitation at 200?rpm, ratio of plant material to solvent at 1?g?:?45?mL and extraction time at 1.5 hour. As for EC, Run 13 with 60°C, 200?rpm, 1?g?:?35?mL and 1 hour had metal chelating activity at IC50 = 0.3817?mg/mL. Both optimized extracts were further partitioned using a solvent system to evaluate the fraction responsible for the chelating activity of the plants. The hexane fraction of CA showed potential activity with chelating activity at IC50 = 0.090 and the ethyl acetate fraction of EC had IC50 = 0.120?mg/mL. The study showed that the response surface methodology helped to reduce the extraction time, temperature and agitation and subsequently improve the chelating activity of the plants in comparison to the conventional method. PMID:23533781

  14. IGF-1 protects cardiac myocytes from hyperosmotic stress-induced apoptosis via CREB

    Microsoft Academic Search

    Carola Maldonado; Paola Cea; Tatiana Adasme; Andrés Collao; Guillermo Díaz-Araya; Mario Chiong; Sergio Lavandero

    2005-01-01

    Hyperosmotic stress stimulates a rapid and pronounced apoptosis in cardiac myocytes which is attenuated by insulin-like growth factor-1 (IGF-1). Because in these cells IGF-1 induces intracellular Ca2+ increase, we assessed whether the cyclic AMP response element-binding protein (CREB) is activated by IGF-1 through Ca2+-dependent signalling pathways. In cultured cardiac myocytes, IGF-1 induced phosphorylation (6.5±1.0-fold at 5min), nuclear translocation (30min post-stimulus)

  15. Why should an immune response activate the stress response? Insights from the insects (the cricket Gryllus texensis).

    PubMed

    Adamo, S A

    2010-02-01

    Mediators of the stress response (e.g. glucocorticoids and norepinephrine) can be immunosuppressive. Nevertheless, immune challenge leads to the release of these compounds in vertebrates. To resolve this paradox, it has been suggested that stress hormones help restore immune homeostasis, preventing self-damage. A comparative approach may provide additional hypotheses as to why an immune challenge induces the release of stress hormones/neurohormones. Octopamine, a neurohormonal mediator of the stress response in the cricket Gryllus texensis, increased in concentration in the hemolymph during an immune challenge. Therefore, the release of stress hormones during an immune response occurs in animals across phyla. Octopamine induced an increase in lipid concentration in the hemolymph. After an acute stress (flying or running) the total number of hemocytes in the hemolymph increased. Injections of octopamine had the same effect, suggesting that it may enhance hemocyte-dependent immune functions. On the other hand, octopamine decreased lysozyme-like activity in vitro, suggesting that it inhibits some immune functions. However, lysozyme-like activity was increased by the presence of heat-killed bacteria in vitro and this increase was significantly augmented by the presence of octopamine. Therefore, the effect of octopamine on immune function differed depending on the presence of pathogens. Stress hormones may help shift immune function into the most optimal configuration depending on the physiological context. PMID:19679179

  16. An activated unfolded protein response promotes retinal degeneration and triggers an inflammatory response in the mouse retina.

    PubMed

    Rana, T; Shinde, V M; Starr, C R; Kruglov, A A; Boitet, E R; Kotla, P; Zolotukhin, S; Gross, A K; Gorbatyuk, M S

    2014-01-01

    Recent studies on the endoplasmic reticulum stress have shown that the unfolded protein response (UPR) is involved in the pathogenesis of inherited retinal degeneration caused by mutant rhodopsin. However, the main question of whether UPR activation actually triggers retinal degeneration remains to be addressed. Thus, in this study, we created a mouse model for retinal degeneration caused by a persistently activated UPR to assess the physiological and morphological parameters associated with this disease state and to highlight a potential mechanism by which the UPR can promote retinal degeneration. We performed an intraocular injection in C57BL6 mice with a known unfolded protein response (UPR) inducer, tunicamycin (Tn) and examined animals by electroretinography (ERG), spectral domain optical coherence tomography (SD-OCT) and histological analyses. We detected a significant loss of photoreceptor function (over 60%) and retinal structure (35%) 30 days post treatment. Analysis of retinal protein extracts demonstrated a significant upregulation of inflammatory markers including interleukin-1? (IL-1?), IL-6, tumor necrosis factor-? (TNF-?), monocyte chemoattractant protein-1 (MCP-1) and IBA1. Similarly, we detected a strong inflammatory response in mice expressing either Ter349Glu or T17M rhodopsin (RHO). These mutant rhodopsin species induce severe retinal degeneration and T17M rhodopsin elicits UPR activation when expressed in mice. RNA and protein analysis revealed a significant upregulation of pro- and anti-inflammatory markers such as IL-1?, IL-6, p65 nuclear factor kappa B (NF-kB) and MCP-1, as well as activation of F4/80 and IBA1 microglial markers in both the retinas expressing mutant rhodopsins. We then assessed if the Tn-induced inflammatory marker IL-1? was capable of inducing retinal degeneration by injecting C57BL6 mice with a recombinant IL-1?. We observed ~19% reduction in ERG a-wave amplitudes and a 29% loss of photoreceptor cells compared with control retinas, suggesting a potential link between pro-inflammatory cytokines and retinal pathophysiological effects. Our work demonstrates that in the context of an established animal model for ocular disease, the persistent activation of the UPR could be responsible for promoting retinal degeneration via the UPR-induced pro-inflammatory cytokine IL-1?. PMID:25522272

  17. An activated unfolded protein response promotes retinal degeneration and triggers an inflammatory response in the mouse retina

    PubMed Central

    Rana, T; Shinde, V M; Starr, C R; Kruglov, A A; Boitet, E R; Kotla, P; Zolotukhin, S; Gross, A K; Gorbatyuk, M S

    2014-01-01

    Recent studies on the endoplasmic reticulum stress have shown that the unfolded protein response (UPR) is involved in the pathogenesis of inherited retinal degeneration caused by mutant rhodopsin. However, the main question of whether UPR activation actually triggers retinal degeneration remains to be addressed. Thus, in this study, we created a mouse model for retinal degeneration caused by a persistently activated UPR to assess the physiological and morphological parameters associated with this disease state and to highlight a potential mechanism by which the UPR can promote retinal degeneration. We performed an intraocular injection in C57BL6 mice with a known unfolded protein response (UPR) inducer, tunicamycin (Tn) and examined animals by electroretinography (ERG), spectral domain optical coherence tomography (SD-OCT) and histological analyses. We detected a significant loss of photoreceptor function (over 60%) and retinal structure (35%) 30 days post treatment. Analysis of retinal protein extracts demonstrated a significant upregulation of inflammatory markers including interleukin-1? (IL-1?), IL-6, tumor necrosis factor-? (TNF-?), monocyte chemoattractant protein-1 (MCP-1) and IBA1. Similarly, we detected a strong inflammatory response in mice expressing either Ter349Glu or T17M rhodopsin (RHO). These mutant rhodopsin species induce severe retinal degeneration and T17M rhodopsin elicits UPR activation when expressed in mice. RNA and protein analysis revealed a significant upregulation of pro- and anti-inflammatory markers such as IL-1?, IL-6, p65 nuclear factor kappa B (NF-kB) and MCP-1, as well as activation of F4/80 and IBA1 microglial markers in both the retinas expressing mutant rhodopsins. We then assessed if the Tn-induced inflammatory marker IL-1? was capable of inducing retinal degeneration by injecting C57BL6 mice with a recombinant IL-1?. We observed ~19% reduction in ERG a-wave amplitudes and a 29% loss of photoreceptor cells compared with control retinas, suggesting a potential link between pro-inflammatory cytokines and retinal pathophysiological effects. Our work demonstrates that in the context of an established animal model for ocular disease, the persistent activation of the UPR could be responsible for promoting retinal degeneration via the UPR-induced pro-inflammatory cytokine IL-1?. PMID:25522272

  18. Delineation of Diverse Macrophage Activation Programs in Response to Intracellular Parasites and Cytokines

    PubMed Central

    Zhang, Shuyi; Kim, Charles C.; Batra, Sajeev; McKerrow, James H.; Loke, P'ng

    2010-01-01

    Background The ability to reside and proliferate in macrophages is characteristic of several infectious agents that are of major importance to public health, including the intracellular parasites Trypanosoma cruzi (the etiological agent of Chagas disease) and Leishmania species (etiological agents of Kala-Azar and cutaneous leishmaniasis). Although recent studies have elucidated some of the ways macrophages respond to these pathogens, the relationships between activation programs elicited by these pathogens and the macrophage activation programs elicited by bacterial pathogens and cytokines have not been delineated. Methodology/Principal Findings To provide a global perspective on the relationships between macrophage activation programs and to understand how certain pathogens circumvent them, we used transcriptional profiling by genome-wide microarray analysis to compare the responses of mouse macrophages following exposure to the intracellular parasites T. cruzi and Leishmania mexicana, the bacterial product lipopolysaccharide (LPS), and the cytokines IFNG, TNF, IFNB, IL-4, IL-10, and IL-17. We found that LPS induced a classical activation state that resembled macrophage stimulation by the Th1 cytokines IFNG and TNF. However, infection by the protozoan pathogen L. mexicana produced so few transcriptional changes that the infected macrophages were almost indistinguishable from uninfected cells. T. cruzi activated macrophages produced a transcriptional signature characterized by the induction of interferon-stimulated genes by 24 h post-infection. Despite this delayed IFN response by T. cruzi, the transcriptional response of macrophages infected by the kinetoplastid pathogens more closely resembled the transcriptional response of macrophages stimulated by the cytokines IL-4, IL-10, and IL-17 than macrophages stimulated by Th1 cytokines. Conclusions/Significance This study provides global gene expression data for a diverse set of biologically significant pathogens and cytokines and identifies the relationships between macrophage activation states induced by these stimuli. By comparing macrophage activation programs to pathogens and cytokines under identical experimental conditions, we provide new insights into how macrophage responses to kinetoplastids correlate with the overall range of macrophage activation states. PMID:20361029

  19. Responsibility modulates pain-matrix activation elicited by the expressions of others in pain

    PubMed Central

    Cui, Fang; Abdelgabar, Abdel-Rahman; Keysers, Christian; Gazzola, Valeria

    2015-01-01

    Here we examine whether brain responses to dynamic facial expressions of pain are influenced by our responsibility for the observed pain. Participants played a flanker task with a confederate. Whenever either erred, the confederate was seen to receive a noxious shock. Using functional magnetic resonance imaging, we found that regions of the functionally localized pain-matrix of the participants (the anterior insula in particular) were activated most strongly when seeing the confederate receive a noxious shock when only the participant had erred (and hence had full responsibility). When both or only the confederate had erred (i.e. participant's shared or no responsibility), significantly weaker vicarious pain-matrix activations were measured. PMID:25800210

  20. Responsibility modulates pain-matrix activation elicited by the expressions of others in pain.

    PubMed

    Cui, Fang; Abdelgabar, Abdel-Rahman; Keysers, Christian; Gazzola, Valeria

    2015-07-01

    Here we examine whether brain responses to dynamic facial expressions of pain are influenced by our responsibility for the observed pain. Participants played a flanker task with a confederate. Whenever either erred, the confederate was seen to receive a noxious shock. Using functional magnetic resonance imaging, we found that regions of the functionally localized pain-matrix of the participants (the anterior insula in particular) were activated most strongly when seeing the confederate receive a noxious shock when only the participant had erred (and hence had full responsibility). When both or only the confederate had erred (i.e. participant's shared or no responsibility), significantly weaker vicarious pain-matrix activations were measured. PMID:25800210

  1. A Central Regulatory System Largely Controls Transcriptional Activation and Repression Responses to Phosphate Starvation in Arabidopsis

    PubMed Central

    Bustos, Regla; Castrillo, Gabriel; Linhares, Francisco; Puga, María Isabel; Rubio, Vicente; Pérez-Pérez, Julian; Solano, Roberto; Leyva, Antonio; Paz-Ares, Javier

    2010-01-01

    Plants respond to different stresses by inducing or repressing transcription of partially overlapping sets of genes. In Arabidopsis, the PHR1 transcription factor (TF) has an important role in the control of phosphate (Pi) starvation stress responses. Using transcriptomic analysis of Pi starvation in phr1, and phr1 phr1-like (phl1) mutants and in wild type plants, we show that PHR1 in conjunction with PHL1 controls most transcriptional activation and repression responses to phosphate starvation, regardless of the Pi starvation specificity of these responses. Induced genes are enriched in PHR1 binding sequences (P1BS) in their promoters, whereas repressed genes do not show such enrichment, suggesting that PHR1(-like) control of transcriptional repression responses is indirect. In agreement with this, transcriptomic analysis of a transgenic plant expressing PHR1 fused to the hormone ligand domain of the glucocorticoid receptor showed that PHR1 direct targets (i.e., displaying altered expression after GR:PHR1 activation by dexamethasone in the presence of cycloheximide) corresponded largely to Pi starvation-induced genes that are highly enriched in P1BS. A minimal promoter containing a multimerised P1BS recapitulates Pi starvation-specific responsiveness. Likewise, mutation of P1BS in the promoter of two Pi starvation-responsive genes impaired their responsiveness to Pi starvation, but not to other stress types. Phylogenetic footprinting confirmed the importance of P1BS and PHR1 in Pi starvation responsiveness and indicated that P1BS acts in concert with other cis motifs. All together, our data show that PHR1 and PHL1 are partially redundant TF acting as central integrators of Pi starvation responses, both specific and generic. In addition, they indicate that transcriptional repression responses are an integral part of adaptive responses to stress. PMID:20838596

  2. Proc. Nati. Acad. Sci. USA Vol. 75, No. 12, pp. 5926-5930, December 1978

    E-print Network

    Dreyfuss, Gideon

    Compartmentalization of cyclic AMP-dependent protein kinases in human erythrocytes (membrane and cytoplasm, September 21, 1978 ABSTRACT The human erythrocyte contains two types of cyclic AMP-dependent protein kinase), and in steroid-responsive tissues in rats subjected to castration, hypophysectomy, or adrenec- tomy (12

  3. Induction of nitric oxide and respiratory burst response in activated goldfish macrophages requires potassium channel activity

    Microsoft Academic Search

    James L Stafford; Fernando Galvez; Gregory G Goss; Miodrag Belosevic

    2002-01-01

    Potassium channel activity is important for modulating mammalian macrophage antimicrobial functions. The involvement of potassium channels in mediation of immune cell function in lower vertebrates, such as teleost, has not been explored. Since relatively little is known about the types of potassium channels present in fish macrophages, pharmacological blockers with broad ranges of activity were tested: 4-aminopyridine (4-AP), quinine, and

  4. Activity-Induced DNA Breaks Govern the Expression of Neuronal Early-Response Genes.

    PubMed

    Madabhushi, Ram; Gao, Fan; Pfenning, Andreas R; Pan, Ling; Yamakawa, Satoko; Seo, Jinsoo; Rueda, Richard; Phan, Trongha X; Yamakawa, Hidekuni; Pao, Ping-Chieh; Stott, Ryan T; Gjoneska, Elizabeta; Nott, Alexi; Cho, Sukhee; Kellis, Manolis; Tsai, Li-Huei

    2015-06-18

    Neuronal activity causes the rapid expression of immediate early genes that are crucial for experience-driven changes to synapses, learning, and memory. Here, using both molecular and genome-wide next-generation sequencing methods, we report that neuronal activity stimulation triggers the formation of DNA double strand breaks (DSBs) in the promoters of a subset of early-response genes, including Fos, Npas4, and Egr1. Generation of targeted DNA DSBs within Fos and Npas4 promoters is sufficient to induce their expression even in the absence of an external stimulus. Activity-dependent DSB formation is likely mediated by the type II topoisomerase, Topoisomerase II? (Topo II?), and knockdown of Topo II? attenuates both DSB formation and early-response gene expression following neuronal stimulation. Our results suggest that DSB formation is a physiological event that rapidly resolves topological constraints to early-response gene expression in neurons. PAPERCLIP. PMID:26052046

  5. Neural activation patterns during response inhibition distinguish adolescents with ADHD, their unaffected siblings, and healthy controls

    PubMed Central

    van Rooij, Daan; Hoekstra, Pieter J.; Mennes, Maarten; von Rhein, Daniel; Thissen, Andrieke J.A.M.; Heslenfeld, Dirk; Zwiers, Marcel P.; Faraone, Stephen V.; Oosterlaan, Jaap; Franke, Barbara