scholarly journals Synergistic Effects of Cyclic AMP-Related Vasodilators and the Phosphatase Inhibitor Okadaic Acid

1993 ◽  
Vol 63 (1) ◽  
pp. 129-131 ◽  
Author(s):  
Asaki Abe ◽  
Hideaki Karaki
Keyword(s):  
Cyclic Amp ◽  
Okadaic Acid ◽  
Synergistic Effects ◽  
Phosphatase Inhibitor

scholarly journals Okadaic acid, a phosphatase inhibitor, induces activation and phosphorylation of the Na+/H+ antiport

1991 ◽  
Vol 266 (23) ◽  
pp. 15406-15413 ◽  
Author(s):  
L. Bianchini ◽  
M. Woodside ◽  
C. Sardet ◽  
J. Pouyssegur ◽  
A. Takai ◽  
...  
Keyword(s):  
Okadaic Acid ◽  
Phosphatase Inhibitor

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

2000 ◽  
Vol 182 (23) ◽  
pp. 6774-6782 ◽  
Author(s):  
Carolyn C. Holcroft ◽  
Susan M. Egan
Keyword(s):  
Cyclic Amp ◽  
Rna Polymerase ◽  
Synergistic Effects ◽  
Receptor Protein ◽  
Mobility Shift ◽  
Α Subunit ◽  
Subunit C ◽  
Cyclic Amp Receptor Protein ◽  
Terminal Domain ◽  
Full Activation

ABSTRACT 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. β-Galactosidase assays of various rhaS-lacZ promoter fusions combined with mobility shift assays indicated that a cyclic AMP receptor protein (CRP) site located at −111.5 is also required for full activation of rhaSR expression. To address the mechanisms of activation by CRP and the RNA polymerase α-subunit C-terminal domain (α-CTD) at rhaSR, we tested the effects of alanine substitutions in CRP activating regions 1 and 2, overexpression of a truncated version of α (α-Δ235), and alanine substitutions throughout α-CTD. We found that DNA-contacting residues in α-CTD are required for full activation, and for simplicity, we discuss α-CTD as a third activator of rhaSR. CRP and RhaR could each partially activate transcription in the absence of the other two activators, and α-CTD was not capable of activation alone. In the case of CRP, this suggests that this activation involves neither an α-CTD interaction nor cooperative binding with RhaR, while in the case of RhaR, this suggests the likelihood of direct interactions with core RNA polymerase. We also found that CRP, RhaR, and α-CTD each have synergistic effects on activation by the others, suggesting direct or indirect interactions among all three. We have some evidence that the α-CTD–CRP and α-CTD–RhaR interactions might be direct. The magnitude of the synergistic effects was usually greater with just two activators than with all three, suggesting possible redundancies in the mechanisms of activation by CRP, α-CTD, and RhaR.

Effects Of Pentoxifylline, Penbutolol, Prenylamine, Clofibric Acid And Nicotinic Acid On The Release Of Prostacyclin-(PGI2-) Like Activity From Rat Aorta In Vivo And In Vitro

1981 ◽  
Author(s):  
K U Weithmann ◽  
A G Hoechst
Keyword(s):  
Cyclic Amp ◽  
Nicotinic Acid ◽  
Ex Vivo ◽  
Synergistic Effects ◽  
Rat Aorta ◽  
Clofibric Acid ◽  
Vessel Walls ◽  
Induced Aggregation

Aortas from rats, treated with 5-20 mg/kg of pentoxifylline (pof), penbutolol, prenylamine, clofibric acid or nicotinic acid showed, ex vivo, a significantly higher release of acid labile PGI2-like anti-aggregatory activity compared to controls. This activity could be suppressed by pre-treatment with 2 mg/kg Indomethacin. When incubated with rat aortas in vitro, pof showed a similar stimulatory effect on PGI2-like release, whereas clofibric-and nicotinic acid had no significant effect in this system. Pof and all other drugs mentioned above in therapeutical concentrations had virtually no effect on induced aggregation of human platelets in vitro. However, in the presence of small amounts PGI2 in vitro, inhibition of aggregation and platelet cyclic AMP are enhanced synergistically above the effects of PGI2 and pof individually.We conclude from these experiments that therapeutic doses of all drugs in our study stimulate in vivo the release of PGI2-like activity from vessel walls, thus inhibiting platelet aggregation in vivo. The primary site of action of pof seems to be the vessel wall, whereas the effect of clofibric acid and nicotinic acid on the vessel walls seem to be secondary. The elevation of platelet cyclic AMP levels which generally parallels PGI2-induced inhibition of aggregation might be further enhanced by pof known as an inhibitor of platelet cyclic AMP phosphodiesterase, thus explaining the observed synergistic effects between PGI2 and pof.

Okadaic acid, a phosphatase inhibitor, decreases macrophage motility

1991 ◽  
Vol 260 (2) ◽  
pp. L105-L112 ◽  
Author(s):  
A. K. Wilson ◽  
A. Takai ◽  
J. C. Ruegg ◽  
P. de Lanerolle
Keyword(s):  
Protein Phosphorylation ◽  
Okadaic Acid ◽  
Light Chain ◽  
Intracellular Signaling ◽  
Mammalian Cells ◽  
Morphological Changes ◽  
Phosphoprotein Phosphatase ◽  
Phosphatase Inhibitor ◽  
Signaling Mechanisms ◽  
Dose Dependent

Cellular locomotion results from a series of spatially and temporally integrated reactions. The coordinated regulation of these reactions requires sensitive intracellular signaling mechanisms. Because protein phosphorylation reactions represent important signaling mechanisms in mammalian cells, we investigated the effect of okadaic acid, a phosphoprotein phosphatase inhibitor, on protein phosphorylation and macrophage motility. Okadaic acid was applied to rat alveolar macrophages, and motility was quantitated by a directed chemotaxis assay. Okadaic acid inhibits macrophage motility in a dose-dependent fashion; the concentrations for 50 and 100% inhibition were 3 and 25 microM, respectively. Protein phosphorylation studies demonstrated a 2.5-fold increase in total protein phosphorylation in macrophages treated with 25 microM okadaic acid. These experiments also demonstrated a dose-dependent increase in the phosphorylation of the 20-kDa light chain of myosin. Moreover, 25 microM okadaic acid 1) maximally increased myosin light chain phosphorylation by 6.6-fold, 2) raised the level of myosin associated with the cytoskeleton from a basal level of 47.0 to 96.7% of the total myosin, and 3) induced profound morphological changes as visualized by scanning electron microscopy. These data correlate an increase in protein phosphorylation with a decrease in macrophage motility. Furthermore, they suggest that phosphoprotein phosphatase inhibition may prevent motility by uncoupling coordinated processes, such as cytoskeletal reorganization, that are essential for macrophage motility.

scholarly journals Control of rat skeletal-muscle phosphorylase phosphatase activity by adrenaline

1978 ◽  
Vol 176 (1) ◽  
pp. 347-350 ◽  
Author(s):  
S H Tao ◽  
F L Huang ◽  
A Lynch ◽  
W H Glinsmann
Keyword(s):  
Skeletal Muscle ◽  
Cyclic Amp ◽  
Phosphatase Activity ◽  
Glycogen Synthase ◽  
Rat Skeletal Muscle ◽  
Inhibitor Activity ◽  
Phosphatase Inhibitor ◽  
Heat Stable ◽  
Muscle Phosphorylase ◽  
Isolated Rat

Administration of adrenaline to an isolated rat hindlimb preparation rapidly decreased muscle phosphorylase phosphatase (EC 3.1.3.17) activity and increased heat-stable and trypsin-labile phosphatase inhibitor activity. This was associated with increased tissue cyclic AMP concentrations, phosphorylase (EC 2.4.1.1) activation and glycogen synthase (EC 2.4.1.11) inactivation.

scholarly journals Estrogenic Compounds or Adiponectin Inhibit Cyclic AMP Response to Human Luteinizing Hormone in Mouse Leydig Tumor Cells

Biology ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 45 ◽  
Author(s):  
Thi Mong Diep Nguyen ◽  
Danièle Klett ◽  
Yves Combarnous
Keyword(s):  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Tumor Cells ◽  
Estrogenic Activity ◽  
Synergistic Effects ◽  
Inhibitory Effect ◽  
Dose Effect ◽  
Sexual Steroids ◽  
Leydig Tumor Cells ◽  
High Concentrations

Mouse Leydig Tumor cells (mLTC), transiently expressing cAMP-dependent luciferase, were used to study the influence of sexual steroids and of adiponectin (ADPN) on the cAMP response to luteinizing hormones (LH). While testosterone and progesterone had no significant effect, several molecules with estrogenic activity (17β-estradiol, ethynylestradiol, and bisphenol A) provoked a decrease in intracellular cyclic AMP accumulation under 0.7 nM human LH stimulation. Adiponectin exhibited a bimodal dose-effect on LH response: synergistic between 2–125 ng/mL and inhibitory between 0.5–5 µg/mL. In brief, our data indicate that estrogens and ADPN separately exert rapid (<1 h) inhibitory and/or synergistic effects on cAMP response to LH in mLTC-1 cells. As the inhibitory effect of each estrogenic molecule was observed after only 1-h preincubation, it might be mediated through the G protein-coupled estrogen receptor (GPER) membrane receptor, but this remains to be demonstrated. The synergistic effect with low concentrations of ADPN with human Luteinizing Hormone (hLH) was observed with both fresh and frozen/thawed ADPN. In contrast, the inhibitory effect with high concentrations of ADPN was lost with frozen/thawed ADPN, suggesting deterioration of its polymeric structure.

Synergistic effects of some metals contaminating mussels on the cytotoxicity of the marine toxin okadaic acid

1999 ◽  
Vol 73 (6) ◽  
pp. 289-295 ◽  
Author(s):  
Adama Traoré ◽  
Michelle Bonini ◽  
Sébastien D. Dano ◽  
Edmond E. Creppy
Keyword(s):  
Okadaic Acid ◽  
Synergistic Effects ◽  
Marine Toxin
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