Search results for "cyclic AMP"
showing 10 items of 177 documents
Effect of LIF-withdrawal on acetylcholine synthesis in the embryonic stem cell line CGR8 is not mediated by STAT3, PI3Ks or cAMP/PKA pathways.
2015
Acetylcholine (ACh) acts as a local cellular signaling molecule and is widely expressed in nature, including mammalian cells and embryonic stem cells. The murine embryonic stem cell line CGR8 synthesizes and releases substantial amounts of ACh. Particularly during early differentiation - a period associated with multiple alterations in geno-/phenotype functions - synthesis and release of ACh are increased by 10-fold. In murine stem cells second messengers of the STAT-3, PI3K and cAMP/PKA pathways are involved in maintaining self-renewal and pluripotency. The present experiments were designed to test whether blockers of these signaling pathways enhance ACh cell content in the presence of LIF…
Phylogenetic origin and transcriptional regulation at the post-diauxic phase of SPI1, in Saccharomyces cerevisiae
2012
15 pages, 4 figures, supplementary material
Hyperphosphorylation of Msn2p and Msn4p in response to heat shock and the diauxic shift is inhibited by cAMP in Saccharomyces cerevisiae.
2000
In response to various stresses, as well as during the diauxic transition, the Msn2p and Msn4p transcription factors of Saccharomyces cerevisiae are activated and induce a large set of genes. This activation is inhibited by the Ras/cAMP/PKA (cAMP-dependent protein kinase) pathway. Here we show by immunoblotting experiments that Msn2p and Msn4p are phosphorylated in vivo during growth on glucose, and become hyperphosphorylated at the diauxic transition and upon heat shock. This hyperphosphorylation is correlated with activation of Msn2/4p-dependent transcription. An increased level of cAMP prevents and reverses these hyperphosphorylations, indicating that kinases other than PKA are involved.…
Serine- and Threonine/Valine-Dependent Activation of PDK and Tor Orthologs Converge on Sch9 to Promote Aging
2014
Dietary restriction extends longevity in organisms ranging from bacteria to mice and protects primates from a variety of diseases, but the contribution of each dietary component to aging is poorly understood. Here we demonstrate that glucose and specific amino acids promote stress sensitization and aging through the differential activation of the Ras/cAMP/PKA, PKH1/2 and Tor/S6K pathways. Whereas glucose sensitized cells through a Ras-dependent mechanism, threonine and valine promoted cellular sensitization and aging primarily by activating the Tor/S6K pathway and serine promoted sensitization via PDK1 orthologs Pkh1/2. Serine, threonine and valine activated a signaling network in which Sch…
Transcriptional activation of apurinic/apyrimidinic endonuclease (Ape, Ref-1) by oxidative stress requires CREB.
1999
Abstract Apurinic/apyrimidinic endonuclease (APE alias Ref-1) is a multifunctional enzyme involved in DNA repair and redox regulation of transcription factors (e.g., AP-1). It also acts as a repressor of its own and other genes. Recently, it was shown that the level of APE mRNA and protein is enhanced upon treatment of cells with oxidative agents, such as hydrogen peroxide (H 2 O 2 ), which gives rise to an adaptive response of cells to oxidative stress. Induction of APE is due to APE promoter activation. To elucidate the mechanism of transcriptional activation of APE by oxidative agents, we introduced mutations into the cloned human APE promoter and checked its activity in transient transf…
A differential role of CREB phosphorylation in cAMP-inducible gene expression in the rat pineal
2000
In the rat pineal gland cAMP mediates nocturnal induction of the enzyme arylalkylamine N-acetyltransferase (AA-NAT) as well as of transcription factors such as inducible cAMP early repressor (ICER), Fos-related antigen-2 (Fra-2) and JunB. Cyclic AMP stimulates the phosphorylation of the DNA binding protein cAMP response element binding protein (CREB). While cAMP-induced CREB phosphorylation appears to be a prerequisite for AA-NAT and ICER gene expression, it is not known whether CREB phosphorylation accounts for the full cAMP response of the two genes. Furthermore, the significance of CREB phosphorylation in cAMP-activated Fra-2 and JunB transcription is unknown. In the present in vitro stu…
Acidic Environment Leads to ROS-Induced MAPK Signaling in Cancer Cells
2011
Tumor micromilieu often shows pronounced acidosis forcing cells to adapt their phenotype towards enhanced tumorigenesis induced by altered cellular signalling and transcriptional regulation. In the presents study mechanisms and potential consequences of the crosstalk between extra- and intracellular pH (pH(e), pH(i)) and mitogen-activated-protein-kinases (ERK1/2, p38) was analyzed. Data were obtained mainly in AT1 R-3327 prostate carcinoma cells, but the principle importance was confirmed in 5 other cell types. Extracellular acidosis leads to a rapid and sustained decrease of pH(i) in parallel to p38 phosphorylation in all cell types and to ERK1/2 phosphorylation in 3 of 6 cell types. Furth…
Indomethacin enhances endothelial NO release — evidence for a role of PGI2 in the autocrine control of calcium-dependent autacoid production
1998
Objective: We studied whether NO or prostacyclin (PGI2), which are continuously released by endothelial cells, have autocrine/paracrine effects on the calcium-dependent autacoid production by modulating the intracellular Ca2+ concentration ([Ca2+]i). Methods: Histamine(His)-induced [Ca2+]i increases (Fura 2-method) and NO-dependent cGMP increase were measured in human umbilical vein endothelial cells (HUVECs) before and after cyclooxygenase inhibition or application of cAMP- and cGMP-elevating drugs. Results: 0.3 μM His increased endothelial [Ca2+]i from 77±2 nM to 418±59 nM. The His-induced [Ca2+]i increases were significantly attenuated following treatment with PGI2 (by 23%) and forskolin…
Characterization of Membrane-Bound Cyclic Nucleotide Phosphodiesterases from Bovine Aortic Smooth Muscle
1992
This study reports the isolation and characterization of cyclic nucleotide phosphodiesterases (PDEs) associated with membrane fraction in comparison to cytosolic forms from bovine aorta. DEAE-Sephacel chromatography of a solubilized membrane fraction from a homogenate, prepared under isotonic conditions in the presence of protease inhibitors, yielded one major peak of PDE activity that specifically hydrolyzed cAMP and was not stimulated by calmodulin: It appeared to contain two subtypes of PDE. The first subtype belonged to the cyclic GMP (cGMP)-inhibited PDE family, (PDE III): It had an apparent Km value of 0.4 microM and was potently inhibited by cGMP, LY186126, and cilostamide. The secon…
On the biochemical classification of yeast trehalases: Candida albicans contains two enzymes with mixed features of neutral and acid trehalase activi…
2009
Abstract Two enzymes endowed with trehalase activity are present in Candida albicans . The cytosolic trehalase (Ntc1p), displayed high activity in exponential phase regardless of the carbon source (glucose, trehalose or glycerol). Ntc1p activity was similar in neutral (pH 7.1) or acid (pH 4.5) conditions, strongly inhibited by ATP, weakly stimulated by divalent cations (Ca 2+ or Mn 2+ ) and unaffected in the presence of cyclic AMP. The Ntc1p activity decreased in stationary phase, except in glycerol-grown cultures, but the catalytic properties did not change. In turn, the cell wall-linked trehalase (Atc1p) showed elevated activity in resting cells or in cultures growing on trehalose or glyc…