WR-2721 inhibits parathyroid adenylate cyclase

1987 ◽  
Vol 252 (2) ◽  
pp. E197-E201 ◽  
Author(s):  
M. E. Weaver ◽  
J. Morrissey ◽  
C. McConkey ◽  
S. Goldfarb ◽  
E. Slatopolsky ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Parathyroid Glands ◽  
Intracellular Camp ◽  
Lower Serum ◽  
Wide Range ◽  
Dose Dependent Decrease ◽  
Camp Levels ◽  
Dose Dependent ◽  
Radioprotective Agent

WR-2721 [S-2-(3-aminopropylamino)ethylphosphorothioic acid] is a chemoprotective and radioprotective agent that has been shown to lower serum calcium in dogs and in humans. This is secondary both to impaired release of Ca2+ from bone and diminished secretion of parathyroid hormone (PTH) from parathyroid glands. Because cAMP plays a role in the regulation of PTH secretion and WR-2721 has been shown to lower cAMP levels in radiated mouse spleen, we investigated the effects of WR-2721 on cAMP production in dispersed bovine parathyroid cells. Additionally, we studied the adenylate cyclase in plasma membranes from normal bovine parathyroid glands after exposure to WR-2721. With parathyroid cells incubated at 0.5 mM Ca2+, addition of WR-2721 in concentrations ranging from 0.02 to 2.0 mM resulted in a progressive decrease in intracellular cAMP (42-50%, respectively). In plasma membranes of bovine parathyroid cells a dose-dependent decrease in adenylate cyclase activity was noted. Inhibition of the cyclase was seen over a wide range of Mg2+ concentrations (2.5-40 mM). WR-2721 inhibited both basal and NaF, Gpp(NH)p, forskolin, and pertussin toxin-stimulated adenylate cyclase. These data suggest that WR-2721 inhibits the activity of parathyroid adenylate cyclase.

scholarly journals PGE2-mediated inhibition of T cell p59fynis independent of cAMP

1999 ◽  
Vol 277 (2) ◽  
pp. C302-C309 ◽  
Author(s):  
Mashkoor A. Choudhry ◽  
Zulfiqar Ahmed ◽  
Mohammed M. Sayeed
Keyword(s):  
T Cells ◽  
T Cell ◽  
Adenylate Cyclase ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Prostaglandin E ◽  
Intracellular Camp ◽  
Sprague Dawley ◽  
Cell Functions ◽  
Camp Levels

We recently observed that prostaglandin E2(PGE2)-mediated suppression of T cell functions could result from an attenuation of p59fynprotein tyrosine kinase activity. The present study evaluated the effects of an adenylate cyclase agonist (forskolin) and antagonist (SQ-22536), as well as those of cAMP analogues (dibutyryl cAMP and 8-bromo- cAMP), on T cell p59fynkinase activity. The study allowed us to assess whether PGE2-mediated activation of adenylate cyclase by itself or the elevation in intracellular cAMP levels is an integral event in the modulation of anti-CD3-linked p59fynactivation in T cells. The experiments were carried out with splenic T cells from male Sprague-Dawley rats. A 30–50% suppression in the autophosphorylation and the kinase activity of p59fynin T cells incubated with PGE2or forskolin was observed. Pretreatment of T cells with SQ-22536 prevented significant PGE2-mediated inhibition of T cell p59fynkinase activity. In contrast, no change in p59fynautophosphorylation and kinase activity in T cells treated with cAMP analogues was observed. These data suggest that PGE2-mediated suppression of p59fynautophosphorylation and kinase activity in T cells is dependent on the activation of adenylate cyclase and independent of the elevation in 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 Calcium and calmodulin in the regulation of human thyroid adenylate cyclase activity

1985 ◽  
Vol 225 (3) ◽  
pp. 581-589 ◽  
Author(s):  
T Lakey ◽  
S Mac Neil ◽  
H Humphries ◽  
S W Walker ◽  
D S Munro ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Metal Ion ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Human Thyroid ◽  
Dependent Manner ◽  
Biphasic Response ◽  
Thyroid Stimulating Immunoglobulins ◽  
Wide Range ◽  
Dose Dependent

TSH (thyrotropin)-stimulated human thyroid adenylate cyclase has a biphasic response to Ca2+, being activated by submicromolar Ca2+ (optimum 22nM), with inhibition at higher concentrations. Calmodulin antagonists caused an inhibition of TSH-stimulated adenylate cyclase in a dose-dependent manner. Inhibition of TSH-and TSIg-(thyroid-stimulating immunoglobulins)-stimulated activity was more marked than that of basal, NaF- or forskolin-stimulated activity. This inhibition was not due to a decreased binding of TSH to its receptor. Addition of pure calmodulin to particulate preparations of human non-toxic goitre which had not been calmodulin-depleted had no effect on adenylate cyclase activity. EGTA was ineffective in removing calmodulin from particulate preparations, but treatment with the tervalent metal ion La3+ resulted in a loss of up to 98% of calmodulin activity from these preparations. Addition of La3+ directly to the adenylate cyclase assay resulted in a partial inhibition of TSH- and NaF-stimulated activity, with 50% inhibition produced by 5.1 microM and 4.0 microM-La3+ respectively. Particulate preparations with La3+ showed a decrease of TSH- and NaF-stimulated adenylate cyclase activity (approx. 40-60%). In La3+-treated preparations there was a decrease in sensitivity of TSH-stimulated adenylate cyclase to Ca2+ over a wide range of Ca2+ concentrations, but most markedly in the region of the optimal stimulatory Ca2+ concentration. In particulate preparations from which endogenous calmodulin had been removed by La3+ treatment, the addition of pure calmodulin caused an increase (73 +/- 22%; mean +/- S.E.M., n = 8) in TSH-stimulated thyroid adenylate cyclase activity. This was seen in 8 out of 13 experiments.

Calcitonin is a competitive inhibitor of the hydrosmotic effect of oxytocin in toad bladder

1988 ◽  
Vol 255 (5) ◽  
pp. E613-E616
Author(s):  
M. Parisi ◽  
C. Ibarra ◽  
M. Ladizesky ◽  
C. Mautalen
Keyword(s):  
Urinary Bladder ◽  
Time Course ◽  
Water Flux ◽  
Competitive Inhibitor ◽  
Intracellular Camp ◽  
Toad Urinary Bladder ◽  
The One ◽  
Toad Bufo ◽  
Camp Levels ◽  
Dose Dependent

The effects of calcitonin (CT) on the water transfer in the toad (Bufo arenarum) urinary bladder, an epithelial barrier commonly employed as a model of the mammalian nephron, were studied. The net transmembrane water flux was measured at minute intervals, while the endogenous adenosine 3',5'-cyclic monophosphate (cAMP) levels were determined in isolated epithelial cells. It was observed that 1) CT, up to 10(-6) M, did not have any effect on water permeability. 2) Preincubation with CT, between 10(-7) and 10(-8) M, inhibited the hydrosmotic response to a supramaximal dose of oxytocin (OXT; 2 x 10(-8) M), used here as an antidiuretic hormone (ADH) analogue. This inhibition was reversible and concentration related. Nevertheless, although the magnitude of the response was reduced, its time course of evolution did not change. 3) When CT was added on the previously developed response to OXT, inhibition was also dose dependent with a time course not distinguishable from hormonal washout. 4) CT, up to 10(-6) M, did not modify the hydrosmotic response to 8-bromo cAMP, a potent analogue of the ADH second messenger. 5) CT and OXT increased the intracellular cAMP levels, but both effects were not cumulative. The increase induced by CT plus OXT was significantly lower than the one elicited by OXT alone. It is concluded that CT is a competitive inhibitor to the hydrosmotic effect of OXT in toad urinary bladder. Its action must be located prior to cAMP formation.

Effects of pituitary adenylate cyclase-activating polypeptide and vasoactive intestinal polypeptide on cyclic AMP accumulation in sheep pituitary cells in vitro

1996 ◽  
Vol 148 (3) ◽  
pp. 545-552 ◽  
Author(s):  
K Sawangjaroen ◽  
C Sernia ◽  
J D Curlewis
Keyword(s):  
Adenylate Cyclase ◽  
Vasoactive Intestinal Polypeptide ◽  
Rapid Development ◽  
Intracellular Camp ◽  
Type I ◽  
Pituitary Cells ◽  
Camp Accumulation ◽  
Pituitary Adenylate Cyclase ◽  
Camp Levels ◽  
Intestinal Polypeptide

Abstract Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) are known to stimulate adenylate cyclase activity in rat pituitary cells but no direct effects have been reported on sheep pituitary cells. In this study we determined whether either peptide could stimulate intracellular cAMP accumulation in dispersed sheep pituitary cells in primary culture. Time course studies with PACAP showed that tachyphylaxis developed rapidly and so a short incubation time (5 min) was used to define the dose–response relationship. PACAP dose-dependently stimulated intracellular cAMP levels with a half-maximum response at 2·9 ± 0·2 nmol/l (n=4). In contrast, VIP only caused a small increase in intracellular cAMP levels at the highest dose tested (1 μmol/l). The VIP antagonist [4C1-d-Phe6,Leu17]VIP had no effect on the cAMP response to either PACAP or VIP while the peptide PACAP(6–38), a putative PACAP antagonist, blocked the cAMP response to PACAP. The desensitisation to PACAP was further investigated by pretreating cells with PACAP for 30 min. After a further 15 min in culture medium alone, these cells showed no cAMP response to subsequent treatment with PACAP but could respond to forskolin. When a longer incubation period of 240 min was used between the first and second treatment with PACAP, a partial return in responsiveness to PACAP was observed. In summary, these results show that PACAP activates adenylate cyclase in sheep pituitary cells but that there is rapid development of tachyphylaxis. Experiments with the antagonists suggest that the response to PACAP is via the PACAP type I receptor. In contrast, physiological doses of VIP do not stimulate cAMP accumulation in sheep pituitary cells. Journal of Endocrinology (1996) 148, 545–552

Octopamine-mediated elevation of cyclic AMP in haemocytes of the American cockroach, Periplaneta americana L.

1987 ◽  
Vol 65 (6) ◽  
pp. 1509-1514 ◽  
Author(s):  
J. W. D. Gole ◽  
G. L. Orr ◽  
R. G. H. Downer
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Adult Male ◽  
Periplaneta Americana ◽  
American Cockroach ◽  
Time Dependent ◽  
Blocking Agents ◽  
Adrenergic Blocking ◽  
Camp Levels ◽  
Dose Dependent

The injection of 10 μL of 5 × 10−3 M octopamine into the haemocoel of adult male Periplaneta americana results in a 20 × increase in haemolymph cyclic AMP (cAMP) levels within 3 min. Synephrine also causes a marked increase in haemolymph cAMP, and less pronounced elevations were obtained following the injection of tyramine, dopamine, norepinephrine, 5-hydroxytryptamine, phenylethanolamine, β-phenylethylamine, and L-phenylephrine. The octopamine effect is time dependent for at least 10 min and dose dependent with the EC50 for the injected dose calculated to be about 2.5 × 10−3 M. These results indicate that the octopamine response is receptor mediated and studies on isolated haemocytes suggest that the octopamine-sensitive receptors are located on haemocytes. Incubation of whole haemocytes in medium containing octopamine results in a dose-dependent elevation of cAMP with the EC50 calculated at about 7.5 × 10−6 M. Synephrine, tyramine, and dopamine also elevate cAMP levels in incubated haemocytes, and the activator of adenylate cyclase, forskolin, causes a marked increase in cAMP. The octopamine-mediated response is blocked by mianserin, phentolamine, and cyproheptadine but not by the β-adrenergic blocking agents propranolol and dichloroisoproterenol.

Mechanism and site of action of a dopamine D1 antagonist in the rabbit retina

1989 ◽  
Vol 3 (6) ◽  
pp. 573-585 ◽  
Author(s):  
Ralph J. Jesen
Keyword(s):  
Adenylate Cyclase ◽  
Ganglion Cells ◽  
Excitatory Amino Acid ◽  
Sch 23390 ◽  
Amacrine Cells ◽  
Intracellular Camp ◽  
Rabbit Retina ◽  
Pharmacological Agents ◽  
Evoked Activity ◽  
Camp Levels

AbstractDopamine D1 antagonists have been shown to alter drastically the spontaneous and light-evoked activity of ganglion cells in the rabbit retina (Jensen & Daw, 1984, 1986). A major target of dopaminergic neurons in mammalian retinas appears to be rod All amacrine cells (Pourcho, 1982; Voigt & Wässle, 1987). In the present study, the following questions were addressed: (1) Do dopamine D1 antagonists alter the activity of ganglion cells through actions primarily on rod All amacrine cells? (2) Are the effects of dopamine D1 antagonists on ganglion cells due to an inhibition of dopamine-stimulated adenylate cyclase activity?Using an isolated, superfused retinal preparation, the ability of several pharmacological agents to counteract the physiological effects of the dopamine D1 antagonist (+)-SCH 23390 on rabbit ganglion cells was examined. The glycine antagonist strychnine abolished the effects of (+)-SCH 23390 on the spontaneous and light-evoked activity of OFF-center ganglion cells, whereas the excitatory amino-acid antagonist kynurenic acid abolished the effects of (+)-SCH 23390 on the spontaneous and light-evoked activity of ON-center ganglion cells. The findings obtained with these antagonists can be explained in terms of the known synaptic connections of All amacrine cells.Both 8-(4-chlorophenylthio) cyclic AMP, a membrane-permeable cAMP analog, and forskolin, an activator of adenylate cyclase, reversed the effects of (+)-SCH 23390 on the spontaneous and light-evoked activity of OFF-center ganglion cells but not ON-center ganglion cells. These findings suggest that the effects of dopamine D1 antagonists on OFF-center ganglion cells are due to an inhibition of dopamine-stimulated adenylate cyclase, with the ensuing lowering of cellular cAMP levels. The effects of dopamine D1 antagonists on ON-center ganglion cells appear, however, to be independent of intracellular cAMP levels.

scholarly journals Cyclic AMP functions as a primary sexual signal in gametes of Chlamydomonas reinhardtii.

1987 ◽  
Vol 105 (5) ◽  
pp. 2279-2292 ◽  
Author(s):  
S M Pasquale ◽  
U W Goodenough
Keyword(s):  
Adenylate Cyclase ◽  
Chlamydomonas Reinhardtii ◽  
Mating Type ◽  
Cyclic Nucleotide ◽  
Actin Polymerization ◽  
Cyclic Nucleotide Phosphodiesterase ◽  
Intracellular Camp ◽  
Opposite Mating Type ◽  
Flagellar Membrane ◽  
Camp Levels

When Chlamydomonas reinhardtii gametes of opposite mating type are mixed together, they adhere by a flagella-mediated agglutination that triggers three rapid mating responses: flagellar tip activation, cell wall loss, and mating structure activation accompanied by actin polymerization. Here we show that a transient 10-fold elevation of intracellular cAMP levels is also triggered by sexual agglutination. We further show that gametes of a single mating type can be induced to undergo all three mating responses when presented with exogenous dibutyryl-cAMP (db-cAMP). These events are also induced by cyclic nucleotide phosphodiesterase inhibitors, which elevate endogenous cAMP levels and act synergistically with db-cAMP. Non-agglutinating mutants of opposite mating type will fuse efficiently in the presence of db-cAMP. No activation of mating events is induced by calcium plus ionophores, 8-bromo-cGMP, dibutyryl-cGMP, nigericin at alkaline pH, phorbol esters, or forskolin. H-8, an inhibitor of cyclic nucleotide-dependent protein kinase, inhibits mating events in agglutinating cells and antagonizes the effects of cAMP on non-agglutinating cells. Adenylate cyclase activity was detected in both the gamete cell body and flagella, with the highest specific activity displayed in flagellar membrane fractions. The flagellar membrane adenylate cyclase is preferentially stimulated by Mn++, unresponsive to NaF, GTP, GTP gamma S, AlF4-, and forskolin, and is inhibited by trifluoperazine. Cyclic nucleotide phosphodiesterase activity is also present in flagella. Our observations indicate that cAMP is a sufficient initial signal for all of the known mating reaction events in C. reinhardtii, and suggest that the flagellar cyclase and/or phosphodiesterase may be important loci of control for the agglutination-stimulated production of this signal.

Epinephrine translocates GLUT-4 but inhibits insulin-stimulated glucose transport in rat muscle

1998 ◽  
Vol 274 (4) ◽  
pp. E700-E707 ◽  
Author(s):  
Xiao-Xia Han ◽  
Arend Bonen
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Glucose Transport ◽  
Plasma Membranes ◽  
Rat Muscle ◽  
Glut 4 ◽  
Glut 4 Translocation ◽  
Dose Dependent Decrease ◽  
Dose Dependent

We examined the effects of epinephrine (25, 50, and 150 nM) on 1) basal and insulin-stimulated 3- O-methylglucose (3-MG) transport in perfused rat muscles and 2) GLUT-4 in skeletal muscle plasma membranes. Insulin increased glucose transport 330–600% in three types of skeletal muscle [white (WG) and red (RG) gastrocnemius and soleus (SOL)]. Glucose transport was also increased by epinephrine (22–48%) in these muscles ( P < 0.05). In contrast, the insulin-stimulated 3-MG transport was reduced by epinephrine in all three types of muscles; maximal reductions were observed at 25 nM epinephrine in WG (−25%) and RG (−32.5%). A dose-dependent decrease occurred in SOL (−27% at 25 nM; −55% at 150 nM, P < 0.05). Insulin (20 mU/ml) and epinephrine (150 nM) each translocated GLUT-4 to the plasma membrane, and no differences in translocation were observed between insulin and epinephrine ( P > 0.05). In addition, epinephrine did not inhibit insulin-stimulated GLUT-4 translocation, and the combined epinephrine and insulin effects on GLUT-4 translocation were not additive. The increase in surface GLUT-4 was associated with increases in muscle cAMP concentrations, but only when epinephrine alone was present. No relationship was evident between muscle cAMP concentrations and surface GLUT-4 in the combined epinephrine and insulin-stimulated muscles. These studies indicate that epinephrine can translocate GLUT-4 while at the same time increasing glucose transport when insulin is absent, or can inhibit glucose transport when insulin is present.

Coxsackievirus B3 entry into the host cell interferes with G-protein-mediated transmembrane signalling

1994 ◽  
Vol 14 (4) ◽  
pp. 205-214
Author(s):  
Jiri Novotny ◽  
Petr Kvapil ◽  
Jeronimo Cello ◽  
Lennart A. Ransnäs
Keyword(s):  
Adenylyl Cyclase ◽  
G Protein ◽  
Plasma Membranes ◽  
Coxsackievirus B3 ◽  
Intracellular Camp ◽  
Transmembrane Signalling ◽  
Signalling System ◽  
System A ◽  
Infected Cells ◽  
Camp Levels

In the present work we used various cell lines in order to study the possible effect of coxsackievirus B3 (CVB3) entry on the adenylyl cyclase transmembrane signalling system. A significant decrease (by about 10–20%) was found in forskolin-augmented as well as in AlF4−- and GTPγS-sensitive adenylyl cyclase activity in plasma membranes isolated from HeLa, HEp-2, Vero and green monkey kidney cells shortly (up to 60 min) preincubated with CVB3 (5 PFU/cell). Moreover, the ability of G-proteins derived from plasma membranes of infected cells to reconstitute AC activity in the cyc− mutant of S49 cells was also reduced. Content of G-protein subunits, however, remained unchanged after CVB3 attachment. Functional alterations in the G-protein-mediated adenylyl cyclase signalling system were accompanied by a marked decrease (by about 20–40%) of intracellular cAMP levels in virus-affected cells. These findings demonstrate clearly that CVB3 may affect functioning of the G-protein regulated adenylyl cyclase transmembrane signalling system in virus-sensitive cells as early as during the first period of its contact with the cellular plasma membrane.

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