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Intracellular cAMP (intracellular + camp)
Terms modified by Intracellular cAMP Selected AbstractsStructural and functional changes in the olfactory pathway of adult Drosophila take place at a critical ageDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2003Jean-Marc Devaud Abstract The olfactory system of several holometabolous insect species undergoes anatomical changes after eclosion of the imago, following those occurring during metamorphosis. In parallel, odor experience and learning performance also evolve with age. Here, we analyze the case of adult Drosophila females. Synaptogenesis in the antennal lobe (AL) starts in late pupa and continues during the first days of adult life, at the same time as the behavioral response to odors matures. Individual olfactory glomeruli (DM6, DM2, and V) display specific growth patterns between days 1 and 12 of adult life. Experience can modify the olfactory pathway both structurally and functionally as shown by adaptation experiments. The modifications associated with this form of nonassociative learning seem to take place at a critical age. Exposure to benzaldehyde at days 2,5 of adult life, but not at 8,11, causes behavioral adaptation as well as structural changes in DM2 and V glomeruli. Altered levels in intracellular cAMP, caused by dunce and rutabaga mutants, do not affect the normal changes in glomerular size, at least at day 6 of development, but they prevent those elicited by experience, establishing a molecular difference between glomerular changes of intrinsic versus environmental origin. Taken together, these data demonstrate an imprinting-like phenomenon in the olfactory pathway of young Drosophila adults, and illustrate its glomerulus-specific dynamics. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 13,23, 2003 [source] Role for cAMP-protein kinase A signalling in augmented neutrophil adhesion and chemotaxis in sickle cell diseaseEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 4 2007Andreia A. Canalli Abstract The significance of the leukocyte in sickle cell disease (SCD) pathophysiology is becoming increasingly recognised; we sought to examine whether the chemotactic properties of neutrophils of SCD individuals may be altered and, further, to better understand the signalling events that mediate altered SCD neutrophil function. Adhesion to immobilised fibronectin (FN) and chemotaxis of control and SCD neutrophils were assessed using in vitro static adhesion assays and 96-well chemotaxis chamber assays. Adhesion assays confirmed a significantly higher basal adhesion of SCD neutrophils to FN, compared with control neutrophils. Chemotaxis assays established, for the first time, that SCD neutrophils demonstrate greater spontaneous migration and, also, augmented migration in response to IL-8, when compared with control neutrophils. Co-incubation of SCD neutrophils with KT5720 (an inhibitor of PKA) abrogated increased basal SCD neutrophil adhesion, spontaneous chemotaxis and IL-8-stimulated chemotaxis. Stimulation of SCD neutrophils with IL-8 also significantly augmented SCD neutrophil adhesion to FN with a concomitant increase in cAMP levels and this increase in adhesion was abolished by KT5720. Interestingly, the adhesive properties of neutrophils from SCD individuals on hydroxyurea therapy were not significantly altered and results indicate that a reduction in intracellular cAMP may contribute to lower the adhesive properties of these cells. Data indicate that up-regulated cAMP signalling plays a significant role in the altered adhesive and migratory properties in SCD neutrophils. Such alterations may have important implications for the pathophysiology of the disease and the cAMP-PKA pathway may represent a therapeutic target for the abrogation of altered leukocyte function. [source] The human basophil , a novel target of the neuropeptide alpha-melanocyte-stimulating hormoneEXPERIMENTAL DERMATOLOGY, Issue 8 2006M. Böhm There is increasing evidence that the basophil does not only play an important role in acute allergic reactions but also in the pathogenesis of chronic allergic disorders. Here we show that human basophils express melanocortin receptors (MC-Rs) and respond to alpha-melanocyte-stimulating hormone (alpha-MSH) with regulation of proallergic cytokine expression and modulation of basophil activation markers. Using primers against all known MC-R subtypes we demonstrate that the human basophil cell line KU812 expresses MC-1R. Expression of MC-1R on the surface of KU812 cells was confirmed by FACS analysis using an anti-MC-1R antibody. The MC-1R expressed by KU812 cells was functionally active as alpha-MSH induced intracellular cAMP in a dose-dependent manner. Moreover, alpha-MSH abrogated the effect of calcium ionophore A23187 on IL-4 mRNA expression in these cells. The relevance of the above findings was corroborated by showing that MC-1R surface expression is also detectable in basophils of leukocyte suspensions derived from whole human blood. Most interestingly, alpha-MSH was capable of suppressing the inductive effect of fMLP on surface expression of the basophil activation marker CD63 in leukocyte suspensions of atopic individuals. Likewise, alpha-MSH significantly blocked grass pollen-induced up-regulation of CD63 in leukocyte suspensions of patients with grass pollen allergy. Our findings highlight a novel functional dimension of alpha-MSH. In addition, MSH peptides may become a novel future therapeutic avenue in treating human allergic diseases. [source] ,-Arrestin2 Regulates the Differential Response of Cortical and Trabecular Bone to Intermittent PTH in Female Mice,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2005Mary L Bouxsein PhD Abstract Cytoplasmic arrestins regulate PTH signaling in vitro. We show that female ,-arrestin2,/, mice have decreased bone mass and altered bone architecture. The effects of intermittent PTH administration on bone microarchitecture differed in ,-arrestin2,/, and wildtype mice. These data indicate that arrestin-mediated regulation of intracellular signaling contributes to the differential effects of PTH at endosteal and periosteal bone surfaces. Introduction: The effects of PTH differ at endosteal and periosteal surfaces, suggesting that PTH activity in these compartments may depend on some yet unidentified mechanism(s) of regulation. The action of PTH in bone is mediated primarily by intracellular cAMP, and the cytoplasmic molecule ,-arrestin2 plays a central role in this signaling regulation. Thus, we hypothesized that arrestins would modulate the effects of PTH on bone in vivo. Materials and Methods: We used pDXA, ,CT, histomorphometry, and serum markers of bone turnover to assess the skeletal response to intermittent PTH (0, 20, 40, or 80 ,g/kg/day) in adult female mice null for ,-arrestin2 (,-arr2,/,) and wildtype (WT) littermates (7-11/group). Results and Conclusions: ,-arr2,/, mice had significantly lower total body BMD, trabecular bone volume fraction (BV/TV), and femoral cross-sectional area compared with WT. In WT females, PTH increased total body BMD, trabecular bone parameters, and cortical thickness, with a trend toward decreased midfemoral medullary area. In ,-arr2,/, mice, PTH not only improved total body BMD, trabecular bone architecture, and cortical thickness, but also dose-dependently increased femoral cross-sectional area and medullary area. Histomorphometry showed that PTH-stimulated periosteal bone formation was 2-fold higher in ,-arr2,/, compared with WT. Osteocalcin levels were significantly lower in ,-arr2,/, mice, but increased dose-dependently with PTH in both ,-arr2,/, and WT. In contrast, whereas the resorption marker TRACP5B increased dose-dependently in WT, 20-80 ,g/kg/day of PTH was equipotent with regard to stimulation of TRACP5B in ,-arr2,/,. In summary, ,-arrestin2 plays an important role in bone mass acquisition and remodeling. In estrogen-replete female mice, the ability of intermittent PTH to stimulate periosteal bone apposition and endosteal resorption is inhibited by arrestins. We therefore infer that arrestin-mediated regulation of intracellular signaling contributes to the differential effects of PTH on cancellous and cortical bone. [source] Role of Rac 1 and cAMP in endothelial barrier stabilization and thrombin-induced barrier breakdownJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2009Y. Baumer Barrier stabilizing effects of cAMP as well as of the small GTPase Rac 1 are well established. Moreover, it is generally believed that permeability-increasing mediators such as thrombin disrupt endothelial barrier functions primarily via activation of Rho A. In this study, we provide evidence that decrease of both cAMP levels and of Rac 1 activity contribute to thrombin-mediated barrier breakdown. Treatment of human dermal microvascular endothelial cells (HDMEC) with Rac 1-inhibitor NSC-23766 decreased transendothelial electrical resistance (TER) and caused intercellular gap formation. These effects were reversed by addition of forskolin/rolipram (F/R) to increase intracellular cAMP but not by the cAMP analogue 8-pCPT-2,-O-Methyl-cAMP (O-Me-cAMP) which primarily stimulates protein kinase A (PKA)-independent signaling via Epac/Rap 1. However, both F/R and O-Me-cAMP did not increase TER above control levels in the presence of NSC-23766 in contrast to experiments without Rac 1 inhibition. Because Rac 1 was required for maintenance of barrier functions as well as for cAMP-mediated barrier stabilization, we tested the role of Rac 1 and cAMP in thrombin-induced barrier breakdown. Thrombin-induced drop of TER and intercellular gap formation were paralleled by a rapid decrease of cAMP as revealed by fluorescence resonance energy transfer (FRET). The efficacy of F/R or O-Me-cAMP to block barrier-destabilizing effects of thrombin was comparable to Y27632-induced inhibition of Rho kinase but was blunted when Rac 1 was inactivated by NSC-23766. Taken together, these data indicate that decrease of cAMP and Rac 1 activity may be an important step in inflammatory barrier disruption. J. Cell. Physiol. 220: 716,726, 2009. © 2009 Wiley-Liss, Inc. [source] Neurosteroid dehydroepiandrosterone exerts anti-apoptotic effects by membrane-mediated, integrated genomic and non-genomic pro-survival signaling pathwaysJOURNAL OF NEUROCHEMISTRY, Issue 5 2008Ioannis Charalampopoulos Abstract Dehydroepiandrosterone (DHEA) protects neural crest-derived PC12 cells from serum deprivation-induced apoptosis via G protein-associated specific plasma membrane-binding sites (mDBS). Here, we studied the signaling pathways involved in the pro-survival effects of DHEA-mediated activation of the mDBS binding sites. Membrane impermeable DHEA-bovine serum albumin (BSA) conjugate induced an acute phosphorylation of the prosurvival kinases Src, protein kinase A (PKA), MEK1/2/ERK1/2, and PI3K/Akt in serum deprived PC12 cells in parallel to an elevation of intracellular cAMP. The physiological significance of these findings was further assessed in a series of experiments using several selective pro-survival kinase inhibitors. Our combined findings suggest that the following sequence of events may take place following activation of mDBS binding sites: DHEA-BSA induces an acute but transient sequential phosphorylation of the pro-survival kinases Src/PKCa/b/MEK1/2/ERK1/2 which, in their turn, activate transcription factors cAMP responsive element binding protein and nuclear factor kappa B which induce the expression of the anti-apoptotic Bcl-2 genes. In parallel, DHEA-BSA increases intracellular cAMP, and the subsequent phosphorylation of PKA kinase and of cAMP responsive element binding protein. Finally, DHEA-BSA induces phosphorylation of PI3K/Akt kinases which, subsequently, lead to phosphorylation/deactivation of the pro-apoptotic Bad. Our findings suggest that the neurosteroid DHEA affects neural crest-derived cell survival by multiple pro-survival signaling pathways comprising an integrated system of non-genomic and genomic mechanisms. [source] Neuroprotective role of bradykinin because of the attenuation of pro-inflammatory cytokine release from activated microgliaJOURNAL OF NEUROCHEMISTRY, Issue 2 2007Mami Noda Abstract Bradykinin (BK) has been reported to be a mediator of brain damage in acute insults. Receptors for BK have been identified on microglia, the pathologic sensors of the brain. Here, we report that BK attenuated lipopolysaccharide (LPS)-induced release of tumor necrosis factor-alpha (TNF-,) and interleukin-1, from microglial cells, thus acting as an anti-inflammatory mediator in the brain. This effect was mimicked by raising intracellular cAMP or stimulating the prostanoid receptors EP2 and EP4, while it was abolished by a cAMP antagonist, a prostanoid receptor antagonist, or by an inhibitor of the inducible cyclooxygenase (cyclooxygenase-2). BK also enhanced formation of prostaglandin E2 and expression of microsomal prostaglandin E synthase. Expression of BK receptors and EP2/EP4 receptors were also enhanced. Using physiological techniques, we identified functional BK receptors not only in culture, but also in microglia from acute brain slices. BK reduced LPS-induced neuronal death in neuron,microglia co-cultures. This was probably mediated via microglia as it did not affect TNF-,-induced neuronal death in pure neuronal cultures. Our data imply that BK has anti-inflammatory and neuroprotective effects in the central nervous system by modulating microglial function. [source] A family of octapamine receptors that specifically induce cyclic AMP production or Ca2+ release in Drosophila melanogasterJOURNAL OF NEUROCHEMISTRY, Issue 2 2005Sabine Balfanz Abstract In invertebrates, the biogenic-amine octopamine is an important physiological regulator. It controls and modulates neuronal development, circadian rhythm, locomotion, ,fight or flight' responses, as well as learning and memory. Octopamine mediates its effects by activation of different GTP-binding protein (G protein)-coupled receptor types, which induce either cAMP production or Ca2+ release. Here we describe the functional characterization of two genes from Drosophila melanogaster that encode three octopamine receptors. The first gene (Dmoa1) codes for two polypeptides that are generated by alternative splicing. When heterologously expressed, both receptors cause oscillatory increases of the intracellular Ca2+ concentration in response to applying nanomolar concentrations of octopamine. The second gene (Dmoa2) codes for a receptor that specifically activates adenylate cyclase and causes a rise of intracellular cAMP with an EC50 of ,3 × 10,8 m octopamine. Tyramine, the precursor of octopamine biosynthesis, activates all three receptors at ,,100-fold higher concentrations, whereas dopamine and serotonin are non-effective. Developmental expression of Dmoa genes was assessed by RT,PCR. Overlapping but not identical expression patterns were observed for the individual transcripts. The genes characterized in this report encode unique receptors that display signature properties of native octopamine receptors. [source] "Soluble" adenylyl cyclase-generated cyclic adenosine monophosphate promotes fast migration in PC12 cellsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2008Jennifer J. Young Abstract In a model for neuronal movement, PC12 cells undergo fast migration in response to nerve growth factor (NGF) and phorbol ester (PMA). We previously showed that NGF increases intracellular cAMP via activation of soluble adenylyl cyclase (sAC). In this report, we demonstrate that sAC activation is an essential component of NGF- + PMA-induced fast migration in PC12 cells. Interestingly, PMA also raises intracellular cAMP but does so by stimulating transmembrane adenylyl cyclases (tmAC); however, this tmAC-generated cAMP does not contribute to fast migration. Therefore, cells must possess independent pools of cAMP capable of modulating distinct functions. © 2007 Wiley-Liss, Inc. [source] The melanocortin system in articular chondrocytes: Melanocortin receptors, pro-opiomelanocortin, precursor proteases, and a regulatory effect of ,-melanocyte,stimulating hormone on proinflammatory cytokines and extracellular matrix componentsARTHRITIS & RHEUMATISM, Issue 10 2009Susanne Grässel Objective The pro-opiomelanocortin (POMC),derived neuropeptide ,-melanocyte,stimulating hormone (,-MSH) mediates its effects via melanocortin (MC) receptors. This study was carried out to investigate the expression patterns of the MC system and the effects of ,-MSH in human articular chondrocytes. Methods Articular chondrocytes established from human osteoarthritic joint cartilage were analyzed by reverse transcription,polymerase chain reaction (RT-PCR) and Western blotting for the expression of MC receptors, POMC, and prohormone convertases (PCs). MC-1 receptor (MC-1R) expression in articular cartilage was further studied by immunohistochemistry. Ca2+ and cAMP assays were used to monitor ,-MSH signaling, while studies of ,-MSH function were performed in cultures with chondrocyte micromass pellets stimulated with ,-MSH. Expression of cytokines and extracellular matrix (ECM) components was determined by real-time RT-PCR, Western immunoblotting, and enzyme-linked immunosorbent assays. Results MC-1R expression was detected in articular chondrocytes in vitro and in articular cartilage in situ. In addition, expression of transcripts for MC-2R, MC-5R, POMC, and PCs was detected in articular chondrocytes. Stimulation with ,-MSH increased the levels of intracellular cAMP, but not Ca2+, in chondrocytes. Both messenger RNA and protein expression of various proinflammatory cytokines, collagens, matrix metalloproteinases (MMPs), and SOX9 was modulated by ,-MSH. Conclusion Human articular chondrocytes are target cells for ,-MSH. The effects of ,-MSH on expression of cytokines and MMPs suggest that this neuropeptide plays a role in inflammatory and degenerative processes in cartilage. It is conceivable that inflammatory reactions can be mitigated by the induction of endogenous MCs or administration of ,-MSH to the affected joints. The induction pattern of regulatory and structural ECM components such as collagens as well as SOX9 and anabolic and catabolic cytokines points to a function of ,-MSH as a trophic factor in skeletal development during endochondral ossification rather than as a factor in homeostasis of permanent cartilage. [source] Phosphodiesterase-linked inhibition of nonmicturition activity in the isolated bladderBJU INTERNATIONAL, Issue 9 2004J.I. Gillespie Over the past few months Gillespie has published several papers in the BJU International investigating the overactive bladder and BOO, using novel models and theories. This next paper continues these concepts and shows that the mechanisms influencing the frequency of agonist-induced phasic activity in the isolated bladder model is slowed by cAMP. These findings will have important implications in future pharmacological strategies in the overactive bladder. OBJECTIVE To explore the influence of intracellular cAMP on phasic activity in the isolated bladder (phasic rises in intravesical pressure associated with waves of contraction and local stretches that can be activated by muscarinic or nicotinic agonists), as it has been argued that this activity underlies nonmicturition contractions, and that it contributes to the generation and modulation of afferent nerve activity. MATERIALS AND METHODS Isolated whole bladders from female guinea pigs (270,300 g) were cannulated via the urethra and suspended in a chamber containing oxygenated Tyrode solution at 33,35 °C. Bladder pressure was recorded and pharmacological agents added to the solution bathing the abluminal surface of the bladder. RESULTS Forskolin (1,3 µmol/L), an activator of adenyl cyclase, reduced the frequency and amplitude of the phasic activity induced by the muscarinic agonist arecaidine (300 nmol/L). There were similar changes in frequency and amplitude in bladders exposed to the nonspecific phosphodiesterase (PDE) inhibitor iso-butyl-methyl-xanthene (IBMX). The actions of specific PDE inhibitors were explored to assess which isoenzymes might be responsible for regulating phasic activity. ENHA (PDE-2), zaprinast (PDE-5, -6, -8, -9 and -11) and siguazodan (PDE-3) had no effect. Zardavarine (PDE-3, -4) and Ro 20-1724 (PDE-4) reduced both the frequency and amplitude of the phasic activity. Nerve-mediated rises in intravesical pressure were also inhibited by Ro 20-1724, and the inhibition was more pronounced at 6.5 Hz than at 30 Hz stimulation. Ro 20-1724 inhibited nerve-mediated fluctuations induced by prolonged (200 s) stimulation at 6.5 Hz. CONCLUSION The mechanisms influencing the frequency of agonist-induced phasic activity in the isolated bladder are slowed by cAMP. Degradation of intracellular cAMP in the cells responsible for phasic activity appears to involve primarily PDE-4. The importance of these observations in relation to the overall physiological regulation of the bladder are discussed, and the possible importance of these findings in the development of pharmacological strategies to modulated bladder activity reviewed. [source] | |||||||||||||