Elevated intracellular cAMP concentration mediates growth suppression in glioma cells

Exposure of CHO-K1 cells in vitro to dibutyryl adenosine cyclic 3',5'-monophosphate (DBcAMP) plus testololactone produces a rapid, reversible antagonism of ligand-induced collection of initially dispersed concanavalin A (Con A) binding sites into a caplike mass. Morphologically, as Con A capping occurs, the cells become less spread and then round completely. With prolonged Con A exposure, cells cultured in either the absence or the presence of DBcAMP plus testololactone cap and round. Capping is blocked by cold treatment and respiratory inhibitors. Colcemid at concentrations greater than 1 muM promotes both Con A capping and cell rounding. Cytochalasin B at similar concentrations inhibits both capping and cell rounding. Treatment of cells with Con A has little effect on intracellular cAMP concentration. Possible mechanisms by which cAMP may modulate the movement of Con A binding sites are discussed.

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cAMP targeting of p38 MAP kinase inhibits thrombin-induced NF-κB activation and ICAM-1 expression in endothelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00072.2004 ◽

2004 ◽

Vol 287 (5) ◽

pp. L1017-L1024 ◽

Cited By ~ 41

Author(s):

Arshad Rahman ◽

Khandaker N. Anwar ◽

Mohd. Minhajuddin ◽

Kaiser M. Bijli ◽

Kamran Javaid ◽

...

Keyword(s):

Endothelial Cells ◽

P38 Mapk ◽

Transcriptional Activity ◽

Umbilical Vein ◽

P38 Map Kinase ◽

Intracellular Camp ◽

Camp Concentration ◽

Binding Function ◽

Umbilical Vein Endothelial Cells ◽

Intracellular Camp Concentration

We investigated the mechanisms by which elevated intracellular cAMP concentration inhibits the thrombin-induced ICAM-1 expression in endothelial cells. Exposure of human umbilical vein endothelial cells to forskolin or dibutyryl cAMP, which increase intracellular cAMP by separate mechanisms, inhibited the thrombin-induced ICAM-1 expression. This effect of cAMP was secondary to inhibition of NF-κB activity, the key regulator of thrombin-induced ICAM-1 expression in endothelial cells. The action of cAMP occurred downstream of IκBα degradation and was independent of NF-κB binding to the ICAM-1 promoter. We observed that cAMP interfered with thrombin-induced phosphorylation of NF-κB p65 (RelA) subunit, a crucial event promoting the activation of the DNA-bound NF-κB. Because p38 MAPK can induce transcriptional activity of RelA/p65 without altering the DNA binding function of NF-κB, we addressed the possibility that cAMP antagonizes thrombin-induced NF-κB activity and ICAM-1 expression by preventing the activation of p38 MAPK. We observed that treating cells with forskolin blocked the activation of p38 MAPK, and inhibition of p38 MAPK interfered with phosphorylation of RelA/p65 induced by thrombin. Our data demonstrate that increased intracellular cAMP concentration in endothelial cells prevents thrombin-induced ICAM-1 expression by inhibiting p38 MAPK activation, which in turn prevents phosphorylation of RelA/p65 and transcriptional activity of the bound NF-κB.

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Ascorbic acid is a regulator of the intracellular cAMP concentration: Old molecule, new functions?

FEBS Letters ◽

10.1016/j.febslet.2008.09.040 ◽

2008 ◽

Vol 582 (25-26) ◽

pp. 3614-3618 ◽

Cited By ~ 27

Author(s):

F. Kaya ◽

S. Belin ◽

Gr. Diamantidis ◽

M. Fontes

Keyword(s):

Ascorbic Acid ◽

Intracellular Camp ◽

Camp Concentration ◽

Intracellular Camp Concentration

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Control of cyclic AMP concentration in bovine endometrial stromal cells by arachidonic acid

Reproduction ◽

10.1530/rep-06-0220 ◽

2007 ◽

Vol 133 (5) ◽

pp. 1017-1026 ◽

Cited By ~ 8

Author(s):

Z Cheng ◽

E L Sheldrick ◽

E Marshall ◽

D C Wathes ◽

D R E Abayasekara ◽

...

Keyword(s):

Arachidonic Acid ◽

Cyclic Amp ◽

Stromal Cells ◽

Inhibitory Effect ◽

Intracellular Camp ◽

Dibutyryl Camp ◽

Camp Concentration ◽

Endometrial Stromal Cells ◽

Kinase C ◽

Intracellular Camp Concentration

Second messenger signalling through cyclic AMP (cAMP) plays an important role in the response of the endometrium to prostaglandin (PG) E2during early pregnancy. Arachidonic acid, which is a by-product of the luteolytic cascade in ruminants, is a potential paracrine signal from the epithelium to the stroma. We investigated the effects of arachidonic acid on the response of the stroma to PGE2. cAMP was measured in bovine endometrial stromal cells treated with agents known to activate or inhibit adenylyl cyclase, protein kinase C (PKC) or phosphodiesterase (PDE). PGE2increased the intracellular cAMP concentration within 10 min, and this effect was attenuated by arachidonic acid and the PKC activator, 4β-phorbol myristate acetate (PMA). The inhibitory effect of arachidonic acid on PGE2-induced cAMP accumulation was prevented by the PKC inhibitor, RO318425, and was absent in cells in which PKC had been downregulated by exposure to PMA for 24 h. The effect of arachidonic acid was also prevented by the PDE inhibitor, 3-isobutyl-1-methylxanthine. Arachidonic acid was shown by immunoblotting to prevent induction of cyclooxygenase-2 by PGE2, forskolin or dibutyryl cAMP. The results indicate that arachidonic acid activates PDE through a mechanism involving PKC, counteracting a rise in intracellular cAMP in response to PGE2. The data suggest that arachidonic acid antagonizes PGE2signalling through cAMP in the bovine endometrium, possibly acting to ensure a rapid return to oestrus in the case of failure of the maternal recognition of pregnancy.

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Cl−-dependent secretory mechanisms in isolated rat bile duct epithelial units

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.2001.281.2.g438 ◽

2001 ◽

Vol 281 (2) ◽

pp. G438-G446 ◽

Cited By ~ 15

Author(s):

Satish K. Singh ◽

Albert Mennone ◽

Alessandro Gigliozzi ◽

Flavia Fraioli ◽

James L. Boyer

Keyword(s):

Bile Duct ◽

Intrahepatic Bile Duct ◽

Fluid Secretion ◽

Intracellular Camp ◽

Camp Concentration ◽

Uptake Pathway ◽

Duct Epithelium ◽

Bile Duct Epithelium ◽

Rat Bile ◽

Intracellular Camp Concentration

Cholangiocytes absorb and secrete fluid, modifying primary canalicular bile. In several Cl−-secreting epithelia, Na+-K+-2Cl− cotransport is a basolateral Cl− uptake pathway facilitating apical Cl− secretion. To determine if cholangiocytes possess similar mechanisms independent of CO2/HCO[Formula: see text], we assessed Cl−-dependent secretion in rat liver isolated polarized bile duct units (IBDUs) by using videomicroscopy. Without CO2/HCO[Formula: see text], forskolin (FSK) stimulated secretion entirely dependent on Na+ and Cl−and inhibited by Na+-K+-2Cl−inhibitor bumetanide. Carbonic anhydrase inhibitor ethoxyzolamide had no effect on FSK-stimulated secretion, indicating negligible endogenous CO2/HCO[Formula: see text] transport. In contrast, FSK-stimulated secretion was inhibited ∼85% by K+ channel inhibitor Ba2+ and blocked completely by bumetanide plus Ba2+. IBDU Na+-K+-2Cl− cotransport activity was assessed by recording intracellular pH during NH4Cl exposure. Bumetanide inhibited initial acidification rates due to NH[Formula: see text] entry in the presence and absence of CO2/HCO[Formula: see text]. In contrast, when stimulated by FSK, a 35% increase in Na+-K+-2Cl− cotransport activity occurred without CO2/HCO[Formula: see text]. These data suggest a cellular model of HCO[Formula: see text]-independent secretion in which Na+-K+-2Cl−cotransport maintains high intracellular Cl−concentration. Intracellular cAMP concentration increases activate basolateral K+ conductance, raises apical Cl−permeability, and causes transcellular Cl− movement into the lumen. Polarized IBDU cholangiocytes are capable of vectorial Cl−-dependent fluid secretion independent of HCO[Formula: see text]. Bumetanide-sensitive Na+-K+-2Cl− cotransport, Cl−/HCO[Formula: see text] exchange, and Ba2+-sensitive K+ channels are important components of stimulated fluid secretion in intrahepatic bile duct epithelium.

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Modulation of ionic permeability in a nonpolarized cell: effect of cAMP

AJP Renal Physiology ◽

10.1152/ajprenal.1989.257.6.f985 ◽

1989 ◽

Vol 257 (6) ◽

pp. F985-F993

Author(s):

R. D. London ◽

M. S. Lipkowitz ◽

R. H. Sinert ◽

R. G. Abramson

Keyword(s):

Normal Subjects ◽

Disulfonic Acid ◽

Intracellular Camp ◽

Red Cell ◽

Relative Permeabilities ◽

Camp Concentration ◽

Chloride Permeability ◽

Polarized Epithelia ◽

Disulfonic Stilbene ◽

Intracellular Camp Concentration

To evaluate whether adenosine 3',5'-cyclic monophosphate (cAMP) modulates ionic permeabilities of nonpolarized cells, as reported in diverse polarized epithelia, relative ionic permeabilities were determined in human red cell ghosts by means of the potential-sensitive fluorescent probe 3,3'-dipropylthiadicarbocyanine iodide. Relative ionic chloride permeability (PCl/PK), but not PNa/PK, was significantly increased in ghosts prepared from normal red blood cells (RBCs) exposed to cAMP analogues or forskolin, with the latter at a concentration that significantly increased intracellular cAMP concentration. As basal RBC cAMP concentrations of untreated uremic subjects were also increased, relative permeabilities of ghosts and unstimulated RBC cAMP concentrations were compared in normal, uremic, and dialyzed subjects, PCl/PK was significantly increased in uremic compared with normal subjects; PNa/PK was not altered. PCl/PK and RBC cAMP concentrations were indistinguishable in normal and dialyzed subjects. Neither the kinetics nor number of Cl(-)-HCO3- antiporters, assessed with the pH-sensitive probe acridine orange and the disulfonic stilbene 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, respectively, were altered in uremic cells. These studies suggest that cAMP modulates ionic chloride permeability via increased chloride conductance of each Cl(-)-HCO3- antiporter or by activation/opening of new or existing channels in RBC membranes.

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Dysregulation of intracellular pH is a cause of impaired capacitation in Slc22a14-deficient mice

Reproduction ◽

10.1530/rep-21-0135 ◽

2021 ◽

Author(s):

Momoe Ito ◽

Masato Unou ◽

Toshiya Higuchi ◽

Shuhei So ◽

Masahiko Ito ◽

...

Keyword(s):

Intracellular Ph ◽

Critical Role ◽

Fertilization Rate ◽

Intracellular Camp ◽

Camp Concentration ◽

Vitro Fertilization ◽

Solute Carrier ◽

Deficient Mice ◽

Intracellular Camp Concentration

Solute carrier 22a member 14 (SLC22A14) plays a critical role in male infertility in mice. We previously revealed that one of the causes of infertility is impaired capacitation. However, the molecular mechanism remained unclear. Here, we show that the influx of HCO3–, a trigger of capacitation, is impaired and intracellular pH is decreased in the sperm of Slc22a14 knockout (KO) mice. While intracellular cAMP concentration did not increase during capacitation in Slc22a14 KO spermatozoa, HCO3–-dependent soluble adenylate cyclase activity was normal, and the addition of 8-bromo cAMP rescued the decreased protein tyrosine phosphorylation. In addition, the intracellular pH of Slc22a14 KO sperm was lower than that of wild-type sperm and did not increase after the addition of HCO3–. Although its relationship to the regulation of intracellular pH is unknown, TMEM225, a possible protein phosphatase inhibitor, was found to be decreased in Slc22a14 KO sperm. The decreased in vitro fertilization rate of Slc22a14 KO sperm was partially rescued by an increase in the intracellular pH (pHi) and the addition of 8-bromo cAMP. These results suggest that SLC22A14 is involved in capacitation through the regulation of HCO3– transport and pHi.

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Identification and Characterization of glxR, a Gene Involved in Regulation of Glyoxylate Bypass in Corynebacterium glutamicum

Journal of Bacteriology ◽

10.1128/jb.186.11.3453-3460.2004 ◽

2004 ◽

Vol 186 (11) ◽

pp. 3453-3460 ◽

Cited By ~ 80

Author(s):

Hyung-Joon Kim ◽

Tae-Hyun Kim ◽

Younhee Kim ◽

Heung-Shick Lee

Keyword(s):

Corynebacterium Glutamicum ◽

Promoter Region ◽

Gel Filtration ◽

Receptor Protein ◽

Predicted Amino Acid Sequence ◽

Intracellular Camp ◽

Camp Concentration ◽

Glyoxylate Bypass ◽

Acetate Medium ◽

Intracellular Camp Concentration

ABSTRACT A corynebacterial clone, previously isolated by scoring repression of lacZYA fused to the aceB promoter of Corynebacterium glutamicum, was analyzed further. In the clone, an open reading frame designated glxR, consisting of 681 nucleotides and encoding a 24,957-Da protein, was found. The molecular mass of a native GlxR protein was estimated by gel filtration column chromatography to be 44,000 Da, suggesting that the protein formed dimers. The predicted amino acid sequence contained both cyclic AMP (cAMP)- and DNA-binding motifs and was homologous with the cAMP receptor protein family of proteins. The aceB-repressing activity of the glxR clone was markedly relieved in an Escherichia coli cya mutant, but the activity was restored in growth medium containing cAMP. In glucose medium, the intracellular cAMP concentration of C. glutamicum reached 22 nmol/mg of protein in the early exponential phase and then decreased further; but in acetate medium, the intracellular cAMP concentration was only 5 nmol/mg of protein and remained low throughout the growth phase. The expression of glxR was not affected by the carbon source. Binding of purified GlxR to the promoter region of aceB could be demonstrated only in the presence of cAMP. These data suggest that GlxR may form dimers which bind to the aceB promoter region in the presence of cAMP and repress the glyoxylate bypass genes.

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