scholarly journals Modulation of cAMP levels by a conserved actinobacteria phosphodiesterase enzyme reduces antimicrobial tolerance in mycobacteria

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Michael Thomson ◽  
Gerald Larrouy-Maumus
Keyword(s):  
Gene Expression ◽  
Antimicrobial Resistance ◽  
Cyclic Amp ◽  
Cell Envelope ◽  
Model Organism ◽  
Intracellular Camp ◽  
Virulence Regulation ◽  
Regulation Of Metabolism ◽  
Altered Cell ◽  
Camp Levels

Antimicrobial tolerance is the gateway to the development of antimicrobial resistance and is therefore a major issue that needs to be tackled. The second messenger, cyclic-AMP (cAMP) is conserved across all taxa of life. It is involved in propagating the signal from environmental stimuli and converting it into a response. In bacteria such as M. tuberculosis (Mtb), P. aeruginosa, V. cholerae and B. pertussis, cAMP has been implicated in virulence, regulation of metabolism and gene expression. Cyclic AMP signalling in mycobacteria is especially complex – with 16 enzymes that produce cAMP in Mtb alone. By discovery of a novel, actinobacteria conserved enzyme that degrades cAMP, we have developed a tool to modulate cAMP levels in mycobacteria. By using a combination of metabolomics, bioenergetics and time-to-kill assays, we show that when this enzyme is overexpressed in the model organism M. smegmatis, there is a 3.3 -fold decrease in intracellular cAMP levels. This was concomitant with 7-fold increased ATP. The unbalanced ATP/cAMP ratio consequently altered cell envelope permeability, compromised bioenergetics and most importantly, led to a decrease in the tolerance to various frontline antimicrobials. Taken together, this work provides clear evidence that cAMP is involved in antimicrobial tolerance in mycobacteria and that this may represent a promising new target for antimicrobial development.

scholarly journals Modulation of the cAMP levels with a conserved actinobacteria phosphodiesterase enzyme reduces antimicrobial tolerance in mycobacteria

2020 ◽  
Author(s):  
Michael Thomson ◽  
Kanokkan Nunta ◽  
Ashleigh Cheyne ◽  
Yi liu ◽  
Acely Garza-Garcia ◽  
...  
Keyword(s):  
Gene Expression ◽  
Antimicrobial Resistance ◽  
Cyclic Amp ◽  
Antimicrobial Susceptibility ◽  
Metabolic Regulation ◽  
Camp Signalling ◽  
The Poor ◽  
Camp Levels ◽  
Increased Susceptibility ◽  
Important Milestone

AbstractAntimicrobial tolerance (AMT) is the gateway to the development of antimicrobial resistance (AMR) and is therefore a major issue that needs to be addressed.The second messenger cyclic-AMP (cAMP), which is conserved across all taxa, is involved in propagating signals from environmental stimuli and converting these into a response. In bacteria, such as M. tuberculosis, P. aeruginosa, V. cholerae and B. pertussis, cAMP has been implicated in virulence, metabolic regulation and gene expression. However, cAMP signalling in mycobacteria is particularly complex due to the redundancy of adenylate cyclases, which are enzymes that catalyse the formation of cAMP from ATP, and the poor activity of the only known phosphodiesterase (PDE) enzyme, which degrades cAMP into 5’- AMP.Based on these two features, the modulation of this system with the aim of investigating cAMP signalling and its involvement in AMT in mycobacteria id difficult.To address this pressing need, we identified a new cAMP-degrading phosphodiesterase enzyme (Rv1339) and used it to significantly decrease the intrabacterial levels of cAMP in mycobacteria. This analysis revealed that this enzyme increased the antimicrobial susceptibility of M. smegmatis mc2155. Using a combination of metabolomics, RNA-sequencing, antimicrobial susceptibility assays and bioenergetics analysis, we were able to characterize the molecular mechanism underlying this increased susceptibility.This work represents an important milestone showing that the targeting of cAMP signalling is a promising new avenue for antimicrobial development and expands our understanding of cAMP signalling in mycobacteria.

Pharmacological characterization of cyclic AMP receptors mediating gene regulation in Dictyostelium discoideum

1986 ◽  
Vol 6 (7) ◽  
pp. 2402-2408
Author(s):  
B Haribabu ◽  
R P Dottin
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Cell Surface Receptor ◽  
Intracellular Camp ◽  
Response Curves ◽  
Pharmacological Characterization ◽  
Surface Receptor ◽  
Extracellular Molecules

Extracellular molecules regulate gene expression in eucaryotes. Exogenous cyclic AMP (cAMP) affects the expression of a large number of developmentally regulated genes in Dictyostelium discoideum. Here, we determine the specificity of the receptor(s) which mediates gene expression by using analogs of cAMP. The order of potency with which these analogs affect the expression of specific genes is consistent with the specificity of their binding to a cell surface receptor and is distinct from their affinity for intracellular cAMP-dependent protein kinase. Dose-response curves with cAMP and adenosine 3',5'-monophosphorothioate, a nonhydrolyzable analog, revealed that the requirement for high concentrations of exogenous cAMP for regulating gene expression is due to the rapid degradation of cAMP by phosphodiesterase. The addition of low concentrations of cAMP (100 nM) or analogs in pulses also regulates gene expression. Both the genes that are positively regulated by exogenous cAMP and the discoidin gene, which is negatively regulated, respond to cAMP analogs to the same degree. Genes expressed in prespore or prestalk cells are also similarly regulated. These data suggest that the effects are mediated through the same receptor. The specificity of this receptor is indistinguishable from that of the well-characterized cell surface cAMP receptor.

scholarly journals Cyclic AMP enhances the sexual agglutinability of Chlamydomonas flagella.

1989 ◽  
Vol 109 (1) ◽  
pp. 247-252 ◽  
Author(s):  
U W Goodenough
Keyword(s):  
Cell Wall ◽  
Cyclic Amp ◽  
Mating Type ◽  
Feedback System ◽  
Intracellular Camp ◽  
Camp Generation ◽  
Sexual Agglutinability ◽  
Single Mating ◽  
Wall Loss ◽  
Camp Levels

Sexual adhesion between Chlamydomonas reinhardtii gametes elicits a rise in intracellular cAMP levels, and exogenous elevation of intracellular cAMP levels in gametes of a single mating type induces such mating responses as cell wall loss, flagellar tip activation, and mating structure activation (Pasquale, S. M., and U. W. Goodenough. 1987. J. Cell Biol. 105:2279-2292). Here evidence is presented that sexual adhesion mobilizes agglutinin to the flagellar surface, and that this mobilization can be induced by exogenous presentation of cAMP to gametes of a single mating type. It is proposed that Chlamydomonas adhesion entails a positive feedback system--initial contacts stimulate the presentation of additional agglutinin--and that this feedback is mediated by adhesion-induced cAMP generation.

Differential regulation of cholesterol side-chain cleavage (P450scc) and aromatase (P450arom) enzyme mRNA expression by gonadotrophins and cyclic AMP in human granulosa cells

1994 ◽  
Vol 12 (2) ◽  
pp. 239-249 ◽  
Author(s):  
E L Yong ◽  
S G Hillier ◽  
M Turner ◽  
D T Baird ◽  
S C Ng ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Mrna Expression ◽  
Granulosa Cells ◽  
Side Chain ◽  
Side Chain Cleavage ◽  
Human Granulosa Cells ◽  
Chain Cleavage ◽  
Camp Levels ◽  
Oestradiol Production

ABSTRACT The co-ordinated biosynthesis of progesterone and oestradiol in the human ovary is critical for reproductive cyclicity and eventual pregnancy. The crucial regulatory enzymes for progesterone and oestradiol biosynthesis in granulosa cells are the cholesterol side-chain cleavage (P450scc) and aromatase (P450arom) enzymes respectively. We utilized the cDNA sequences encoding P450arom and P450scc to examine the roles of FSH and LH, and their intracellular second messenger, cyclic AMP (cAMP), in regulating steroidogenic gene expression. Mature granulosa cells (aspirated before the onset of the endogenous LH surge) and granulosa lutein cells (obtained after an ovulatory dose of human chorionic gonadotrophin) were cultured for 4 days with FSH, LH or dibutyryl cAMP (dbcAMP). After the period of culture, total RNA was extracted from granulosa cells and Northern analyses were performed utilizing 32P-labelled cDNAs encoding P450arom and P450scc. Spent culture media were analysed for steroid and cAMP content. Both FSH and LH strongly stimulated P450arom mRNA expression and oestradiol production in mature granulosa cells. On the other hand, P450scc mRNA expression and progesterone biosynthesis were weakly induced by FSH; maximal synthesis occurred only in the presence of LH. With both gonadotrophins at equivalent concentrations, LH generated a 30-fold higher level of cAMP than FSH. Furthermore, the differential effects of FSH and LH on P450 mRNA expression were reproduced by the presence of low and high concentrations of dbcAMP respectively. LH (and high levels of dbcAMP) increased P450arom mRNA expression in mature granulosa cells but inhibited its accumulation in granulosa lutein cells. In contrast, it stimulated P450scc mRNA expression and progesterone synthesis in both mature granulosa and granulosa lutein cells. Therefore, FSH/low cAMP levels stimulated P450arom gene expression and oestradiol production, while LH/high cAMP levels maximally induced P450scc gene expression and function, in a development-related manner consistent with steroid production in vivo. These findings support the hypothesis that one set of genes (like P450arom) in human granulosa cells is regulated by FSH/low cAMP levels and another (like P450scc) by LH/high cAMP levels.

scholarly journals Changes in gene expression in the Ras/adenylate cyclase system of Saccharomyces cerevisiae: correlation with cAMP levels and growth arrest.

1993 ◽  
Vol 4 (7) ◽  
pp. 757-765 ◽  
Author(s):  
M Russell ◽  
J Bradshaw-Rouse ◽  
D Markwardt ◽  
W Heideman
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Adenylate Cyclase ◽  
Oxidative Metabolism ◽  
Growth Arrest ◽  
Intracellular Camp ◽  
Adenylate Cyclase System ◽  
Diauxic Shift ◽  
Yeast Saccharomyces Cerevisiae ◽  
Camp Levels

Levels of cyclic 3',5'-cyclic monophosphate (cAMP) play an important role in the decision to enter the mitotic cycle in the yeast, Saccharomyces cerevisiae. In addition to growth arrest at stationary phase, S. cerevisiae transiently arrest growth as they shift from fermentative to oxidative metabolism (the diauxic shift). Experiments examining the role of cAMP in growth arrest at the diauxic shift show the following: 1) yeast lower cAMP levels as they exhaust their glucose supply and shift to oxidative metabolism of ethanol, 2) a reduction in cAMP is essential for traversing the diauxic shift, 3) the decrease in adenylate cyclase activity is associated with a decrease in the expression of CYR1 and CDC25, two positive regulators of cAMP levels and an increase in the expression of IRA1 and IRA2, two negative regulators of intracellular cAMP, 4) mutants carrying disruptions in IRA1 and IRA2 were unable to arrest cell division at the diauxic shift and were unable to progress into the oxidative phase of growth. These results indicate that changes cAMP levels are important in regulation of growth arrest at the diauxic shift and that changes in gene expression plays a role in the regulation of the Ras/adenylate cyclase system.

scholarly journals Adenosine 3':5'-monophosphate content and actions in the division cycle of synchronized HeLa cells.

1976 ◽  
Vol 71 (2) ◽  
pp. 515-534 ◽  
Author(s):  
C E Zeilig ◽  
R A Johnson ◽  
E W Sutherland ◽  
D L Friedman
Keyword(s):  
Cell Cycle ◽  
Cyclic Amp ◽  
Hela Cells ◽  
S Phase ◽  
Intracellular Camp ◽  
Specific Effects ◽  
Low Concentrations ◽  
High Concentrations ◽  
Camp Levels ◽  
Stimulation Of

The involvement of adenosine 3':5'-monophosphate (cAMP) in the regulation of the cell cycle was studied by determining intracellular fluctuations in cAMP levels in synchronized HeLa cells and by testing the effects of experimentally altered levels on cell cycle traverse. Cyclic AMP levels were lowest during mitosis and were highest during late G-1 or early S phase. These findings were supported by results obtained when cells were accumulated at these points with Colcemid or high levels of thymidine. Additional fluctuations in cAMP levels were observed during S phase. Two specific effects of cAMP on cell cycle traverse were found. Elevation of cAMP levels in S phase or G-2 caused arrest of cells in G-2 for as long as 10 h and lengthened M. However, once cells reached metaphase, elevation of cAMP accelerated the completion of mitosis. Stimulation of mitosis was also observed after addition of CaCl2. The specificity of the effects of cAMP was verified by demonstrating that: (a) intracellular cAMP was increased after exposure to methylisobutylxanthine (MIX) before any observed effects on cycle traverse; (b) submaximal concentrations of MIX potentiated the effects of isoproterenol; and (c) effects of MIX and isoproterenol were mimicked by 8-Br-cAMP. MIX at high concentrations inhibited G-1 traverse, but this effect did not appear to be mediated by cAMP. Isoproterenol slightly stimulated G-1 traverse and partially prevented the MIX-induced delay. Moreover, low concentrations of 8-Br-cAMP (0.10-100 muM) stimulated G-1 traverse, whereas high concentrations (1 mM) inhibited. Both of these effects were also observed with the control, Br-5'-AMP, at 10-fold lower concentrations.

scholarly journals Cyclic AMP Promotes Neuronal Survival by Phosphorylation of Glycogen Synthase Kinase 3β

2000 ◽  
Vol 20 (24) ◽  
pp. 9356-9363 ◽  
Author(s):  
Mingtao Li ◽  
Xiaomin Wang ◽  
Mary Kay Meintzer ◽  
Tracey Laessig ◽  
Morris J. Birnbaum ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Glycogen Synthase ◽  
Neuronal Survival ◽  
Glycogen Synthase Kinase ◽  
Intracellular Camp ◽  
Glycogen Synthase Kinase 3Β ◽  
Gsk 3Β ◽  
Camp Levels

ABSTRACT Agents that elevate intracellular cyclic AMP (cAMP) levels promote neuronal survival in a manner independent of neurotrophic factors. Inhibitors of phosphatidylinositol 3 kinase and dominant-inactive mutants of the protein kinase Akt do not block the survival effects of cAMP, suggesting that another signaling pathway is involved. In this report, we demonstrate that elevation of intracellular cAMP levels in rat cerebellar granule neurons leads to phosphorylation and inhibition of glycogen synthase kinase 3β (GSK-3β). The increased phosphorylation of GSK-3β by protein kinase A (PKA) occurs at serine 9, the same site phosphorylated by Akt. Purified PKA is able to phosphorylate recombinant GSK-3β in vitro. Inhibitors of GSK-3 block apoptosis in these neurons, and transfection of neurons with a GSK-3β mutant that cannot be phosphorylated interferes with the prosurvival effects of cAMP. These data suggest that activated PKA directly phosphorylates GSK-3β and inhibits its apoptotic activity in neurons.

scholarly journals A 3′,5′ Cyclic AMP (cAMP) Phosphodiesterase Modulates cAMP Levels and Optimizes Competence in Haemophilus influenzae Rd

1998 ◽  
Vol 180 (17) ◽  
pp. 4401-4405 ◽  
Author(s):  
Leah P. Macfadyen ◽  
Caixia Ma ◽  
Rosemary J. Redfield
Keyword(s):  
Cyclic Amp ◽  
Haemophilus Influenzae ◽  
Competence Development ◽  
Intracellular Camp ◽  
Camp Phosphodiesterase ◽  
E Coli ◽  
Sugar Fermentation ◽  
Endogenous Production ◽  
Camp Levels ◽  
Dependent Processes

ABSTRACT Changes in intracellular 3′,5′ cyclic AMP (cAMP) concentration regulate the development of natural competence inHaemophilus influenzae. In Escherichia coli, cAMP levels are modulated by a cAMP phosphodiesterase encoded by the cpdA gene. We have used several approaches to demonstrate that the homologous icc gene of H. influenzae encodes a functional cAMP phosphodiesterase and that this gene limits intracellular cAMP and thereby influences competence and other cAMP-dependent processes. In E. coli, expression of cloned icc reduced both cAMP-dependent sugar fermentation and β-galactosidase expression, as has been shown forcpdA. In H. influenzae, an icc null mutation increased cAMP-dependent sugar fermentation and competence development in strains where these processes are limited by mutations reducing cAMP synthesis. When endogenous production of cAMP was eliminated by a cya mutation, an icc strain was 10,000-fold more sensitive to exogenous cAMP than anicc + strain. The icc strain showed moderately elevated competence under noninducing conditions, as expected, but had subnormal competence increases at onset of stationary phase in rich medium, and on transfer to a nutrient-limited medium, suggesting that excessive cAMP may interfere with induction. Consistent with this finding, a cya strain cultured in 1 mM cAMP failed to develop maximal competence on transfer to inducing conditions. Thus, by limiting cAMP levels, the H. influenzae cAMP phosphodiesterase may coordinate its responses to nutritional stress, ensuring optimal competence development.

scholarly journals Modulation of Cyclic AMP Levels in Fallopian Tube Cells by Natural and Environmental Estrogens

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1250
Author(s):  
Marinella Rosselli ◽  
Barbara P. S. Cometti ◽  
Brigitte Leeners ◽  
Marta Ewa Szutkowska ◽  
Edwin K. Jackson ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Fallopian Tube ◽  
Early Embryo ◽  
Environmental Estrogens ◽  
Intracellular Camp ◽  
Paracrine Factors ◽  
Creb Phosphorylation ◽  
Adrenoceptor Agonist ◽  
17Β Estradiol ◽  
Camp Levels

Autocrine/paracrine factors generated in response to 17β-estradiol (E2) within the fallopian tube (FT) facilitate fertilization and early embryo development for implantation. Since cyclic AMP (cAMP) plays a key role in reproduction, regulation of its synthesis by E2 may be of biological/pathophysiological relevance. Herein, we investigated whether cAMP production in FT cells (FTCs) is regulated by E2 and environmental estrogens (EE’s; xenoestrogens and phytoestrogens). Under basal conditions, low levels of extracellular cAMP were detectable in bovine FTCs (epithelial cells and fibroblasts; 1:1 ratio). Treatment of FTCs with forskolin (AC; adenylyl cyclase activator), isoproterenol (β-adrenoceptor agonist) and IBMX (phosphodiesterase (PDE) inhibitor) dramatically (>10 fold) increased cAMP; whereas LRE1 (sAC; soluble AC inhibitor) and 2’,5’-dideoxyadenosine (DDA; transmembrane AC (tmAC)) inhibitor decreased cAMP. Comparable changes in basal and stimulated intracellular cAMP were also observed. Ro-20-1724 (PDE-IV inhibitor), but not milrinone (PDE-III inhibitor) nor mmIBMX (PDE-I inhibitor), augmented forskolin-stimulated cAMP levels, suggesting that PDE-IV dominates in FTCs. E2 increased cAMP levels and CREB phosphorylation in FTCs, and these effects were mimicked by EE’s (genistein, 4-hydroxy-2’,4’,6’-trichlorobiphenyl, 4-hydroxy-2’,4’,6’-dichlorobiphenyl). Moreover, the effects of E2 and EE were blocked by the tmAC inhibitor DDA, but not by the ERα/β antagonist ICI182780. Moreover, BAPTA-AM (intracellular-Ca2+ chelator) abrogated the effects of E2, but not genistein, on cAMP suggesting differential involvement of Ca2+. Treatment with non-permeable E2-BSA induced cAMP levels and CREB-phosphorylation; moreover, the stimulatory effects of E2 and EEs on cAMP were blocked by G15, a G protein-coupled estrogen receptor (GPER) antagonist. E2 and IBMX induced cAMP formation was inhibited by LRE1 and DDA suggesting involvement of both tmAC and sAC. Our results provide the first evidence that in FTCs, E2 and EE’s stimulate cAMP synthesis via GPER. Exposure of the FT to EE’s and PDE inhibitors may result in abnormal non-cyclic induction of cAMP levels which may induce deleterious effects on reproduction.

Forskolin and thyrotrophin stimulation of rat FRTL-5 thyroid cell growth: the role of cyclic AMP

1987 ◽  
Vol 114 (2) ◽  
pp. 199-205 ◽  
Author(s):  
P. A. Ealey ◽  
C. A. Ahene ◽  
J. M. Emmerson ◽  
N. J. Marshall
Keyword(s):  
Cyclic Amp ◽  
Dose Range ◽  
Phosphodiesterase Inhibitor ◽  
Lag Phase ◽  
Thyroid Cell ◽  
Intracellular Camp ◽  
Camp Levels ◽  
Tsh Stimulation ◽  
Stimulation Of

ABSTRACT The adenylate cyclase stimulator forskolin increases intracellular cyclic AMP (cAMP) in rat FRTL-5 cells within minutes and, after a lag phase of 20–24 h, an increase of cells in metaphase is seen. The dose– response relationships were similar in both systems, with significant increases in the number of metaphases observed at ∼0·1 μmol/l and a doubling of cAMP levels at 1 μmol/l, whilst doses of 0·1 mmol/l and above proved cytotoxic. An involvement of intracellular cAMP as a positive intermediate in cell division was further suggested by the finding that a low dose of forskolin (0·1 μmol/l) potentiated TSH stimulation of mitosis. Isobutyl methyl xanthine (IBMX), a phosphodiesterase inhibitor, also acted as a mitogen and potentiated TSH action. Moreover, the simultaneous inclusion of low doses of IBMX and forskolin additionally potentiated TSH stimulation of mitosis. An analogue of cAMP, dibutyryl cAMP, also stimulated mitosis and acted over a restricted dose range, with maximal stimulation at 1 mmol/l. We conclude that cAMP may act as a positive signal for FRTL-5 thyroid cell proliferation. J. Endocr. (1987) 114, 199–205

Sign in / Sign up

Export Citation Format

Share Document