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.

Adenylate cyclase agonist properties of CGP-12177A in brown fat: evidence for atypical beta-adrenergic receptors

1991 ◽  
Vol 260 (2) ◽  
pp. E226-E231
Author(s):  
P. J. Scarpace ◽  
M. Matheny
Keyword(s):  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Adenylate Cyclase System ◽  
Dependent Manner ◽  
Beta Adrenergic ◽  
Brown Adipose ◽  
Adrenergic Antagonist ◽  
Dose Dependent ◽  
Binding Curves

Thermogenesis in brown adipose tissue (BAT) is stimulated by catecholamine activation of adenylate cyclase through the beta-adrenergic receptor. Recently it was reported that the beta-adrenergic antagonist CGP-12177A stimulates oxygen consumption in BAT. To investigate the mechanism of action of CGP-12177A in BAT, we assessed the inhibitory and stimulatory affects of CGP-12177A on the adenylate cyclase system in myocardial and BAT membranes from rats. CGP-1277A inhibited isoproterenol-stimulated adenylate cyclase activity in a dose-dependent manner, with an inhibitory constant (Ki) of 1.94 +/- 0.18 microM in BAT and 0.49 +/- 0.11 microM in the heart. However, in the absence of isoproterenol, CGP-12177A stimulated adenylate cyclase in BAT with two components of activation, and half-maximal stimulation occurred at 1 microM and 1.5 mM. In contrast, CGP-12177A did not stimulate adenylate cyclase activity in heart membranes. Propranolol inhibited the isoproterenol-stimulated activity with a potency that was one log less in BAT compared with heart. Propranolol fully blocked the high-affinity component but only weakly blocked the low-affinity component of CGP-12177A-stimulated activity in BAT. Pindolol was also less potent in BAT but inhibited the CGP-12177A-stimulated activity in a manner similar to the inhibition of the isoproterenol-stimulated activity, suggesting the CGP-12177A activation was beta-receptor mediated. Binding curves of [125I]iodocyanopindolol ([125I]ICYP) in competition with CGP-12177A demonstrated a shift to lower affinity in the presence of beta,gamma-imidoguanosine 5'-triphosphate, indicating that CGP-12177A has agonist properties with respect to the [125I]ICYP binding site.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermal growth factor receptors and adenylate cyclase activity in human thyroid tissues

1990 ◽  
Vol 14 (3) ◽  
pp. 410-417 ◽  
Author(s):  
Quan-Yang Duh ◽  
Allan E. Siperstein ◽  
Rebecca A. Miller ◽  
Joan J. Sancho ◽  
Michael J. Demeure ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Adenylate Cyclase ◽  
Growth Factor Receptors ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Human Thyroid ◽  
Epidermal Growth Factor Receptors ◽  
Epidermal Growth

Effect of histamine on canine gastric mucosal adenylate cyclase.

1977 ◽  
Vol 232 (1) ◽  
pp. E35
Author(s):  
R R Dozois ◽  
A Wollin ◽  
R D Rettmann ◽  
T P Dousa
Keyword(s):  
Gastric Mucosa ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Antral Mucosa ◽  
Fundic Mucosa ◽  
H2 Receptors ◽  
Dose Dependent ◽  
Stimulation Of

The effects of histamine, Nalpha-dimethylhistamine, 4,5-methylhistamine, Ntau-methylhistamine, pentagastrin, carbachol, and NaF on the adenylate cyclase activity from canine gastric mucosa were investigated in cell-free preparations. In gastric fundic mucosa, histamine (10(-4) M), Nalpha-dimethylhistamine (10(-4) M), 4,5-methylhistamine (10(-4 M), and NaF (10)-2) M) significantly (P less than 0.001) increased adenylate cyclase activity (means+/-SE) by 44.7+/-6.6, 49.4+/-6.7, 34.0+/-6.4, and 572.0+/-100%, respectively, above basal activity. The effect of histamine and Na-dimethyl histamine was dose-dependent. In contrast, other tested agents failed to stimulate the formation of cyclic AMP in gastric fundic mucosa. Metiamide (10(-4) M) blocked the stimulation of fundic mucosa adenylate cyclase by histamine and Nalpha-dimethylhistamine, without significantly altering basal and NaF-induced adenylate cyclase activity. Histamine, however, did not stimulate the adenylate cyclase activity from the gastric antral mucosa. The findings support the proposal that the canine gastric acid response to histamine may be mediated by cyclic AMP formed in response to stimulation of histamine H2-receptors.

scholarly journals The metabolism of cyclic nucleotides in the guinea-pig pancreas. Adenylate cyclase and guanylate cyclase

1980 ◽  
Vol 186 (2) ◽  
pp. 499-505 ◽  
Author(s):  
M Lemon ◽  
P Methven ◽  
K Bhoola
Keyword(s):  
Adenylate Cyclase ◽  
Guinea Pig ◽  
Guanylate Cyclase ◽  
Cyclic Nucleotides ◽  
Cyclase Activity ◽  
Dependent Manner ◽  
Guanylate Cyclase Activity ◽  
Triton X ◽  
Dose Dependent ◽  
Significant Activation

Adenylate cyclase from the guinea-pig pancreas was activated in a dose-dependent manner by both secretin and cholecystokinin-pancreozymin, but in contrast with results in other species the hormones were approximately equipotent. All other hormones and transmitter substances tested were without any effect on adenylate cyclase activity. Guanylate cyclase activity was shown to have both particulate and supernatant components in the guinea-pig pancreas. The particulate enzyme, but not the supernatant enzyme, was markedly activated by Triton X-100, and most of the induced activity was released into the supernatant. The supernatant enzyme was specifically Mn2+-dependent, but, even though Mn2+ was maximally effective at a concentration of 3 mM, activity could be raised further by increasing Ca2+ concentration. The particulate enzyme, by contrast, was relatively Mn2+-independent. Activity of the particulate guanylate cyclase was enhanced by phosphatidylserine. The supernatant enzyme displayed classical Michaelis-Menten kinetics, but the particulate enzyme deviated markedly from such kinetics. Under none of the conditions used was any significant activation of guanylate cyclase observed with any of the secretogen hormones or transmitter substances.

Tannin inhibits adenylate cyclase in airway epithelial cells

1995 ◽  
Vol 268 (5) ◽  
pp. L851-L855
Author(s):  
M. M. Cloutier ◽  
L. Guernsey
Keyword(s):  
Epithelial Cells ◽  
Adenylate Cyclase ◽  
Cholera Toxin ◽  
Airway Epithelial Cells ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Airway Epithelial ◽  
Camp Production ◽  
Dose Dependent ◽  
In Cells

Tannin, isolated from cotton bracts extract and implicated in the pathogenesis of byssinosis, inhibits adenosine 3',5'-cyclic monophosphate (cAMP) production and Cl- secretion in bovine airway epithelial cells in part by inhibiting adrenergic receptor binding. The purpose of this study was to determine whether tannin affected other parts of the adrenergic-cAMP signal transduction pathway by examining the effect of tannin on guanosine 5'-triphosphate (GTP)-regulatory pathways (G proteins) and on adenylate cyclase activity. cAMP production in confluent airway epithelial cells was measured in the presence of cholera toxin (100 micrograms/ml), an activator of GS proteins, and forskolin (0.1-1,000 microM), a direct activator of adenylate cyclase. Cholera toxin stimulated cAMP production; this response, however, was inhibited in cells pretreated with 50 micrograms/ml tannin. Forskolin (100 microM) stimulated cAMP production 13-fold above baseline values. Tannin pretreatment inhibited the stimulatory effect of forskolin on cAMP release in a dose-dependent manner with a tannin concentration causing 50% inhibition of 7.5 micrograms/ml. The stimulatory effect of forskolin on cAMP release was completely inhibited in cells pretreated with 50 micrograms/ml tannin. The inhibition was reversible 3 h after removal of tannin from the solution. Tannin also inhibited forskolin-stimulated adenylate cyclase activity in a dose-dependent, noncompetitive manner. We conclude that forskolin and cholera toxin stimulate cAMP production in airway epithelial cells and that tannin inhibits the production of cAMP in airway epithelial cells by a direct effect on adenylate cyclase activity.

scholarly journals Detection and analysis of agonist-induced formation of the complex of the stimulatory guanine nucleotide-binding protein with adenylate cyclase in intact wild-type and β2-adrenoceptor-expressing NG108-15 cells

1995 ◽  
Vol 308 (1) ◽  
pp. 275-281 ◽  
Author(s):  
G D Kim ◽  
I C Carr ◽  
G Milligan
Keyword(s):  
Adenylate Cyclase ◽  
Nucleotide Binding ◽  
Dose Effect ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Guanine Nucleotide ◽  
Guanine Nucleotide Binding Protein ◽  
Guanine Nucleotide Binding ◽  
Dose Dependent ◽  
Stimulation Of

Neuroblastoma x glioma hybrid, NG108-15, cells appear to express the alpha-subunit of the guanine nucleotide-binding protein Gs in a substantial molar excess over its effector adenylate cyclase [Kim, Adie and Milligan (1994) Eur. J. Biochem. 219, 135-143]. Addition of the IP prostanoid receptor agonist iloprost to intact NG108-15 cells resulted in a dose-dependent increase in formation of the complex between Gs alpha and adenylate cyclase (GSAC) as measured by specific high-affinity binding of [3H]forskolin. NG108-15 cells transfected to express either relatively high (clone beta N22) or low (clone beta N17) levels of beta 2-adrenoceptor both showed dose-dependent increases in specific [3H]forskolin binding in response to the beta-adrenoceptor agonist isoprenaline, and maximally effective concentrations of isoprenaline resulted in the generation of similar numbers of GSAC complexes in both clones. The dose-effect curve for clone beta N22, however, was some 15-fold to the left of that for clone beta N17, which is similar to that noted for isoprenaline-mediated stimulation of adenylate cyclase activity [Adie and Milligan (1994) Biochem. J. 303, 803-808]. In contrast, dose-effect curves for iloprost stimulation of [3H]forskolin binding were not different in clones beta N22 and beta N17. Basal specific [3H]forskolin binding in the absence of agonist was significantly greater in cells of clone beta N22 than clone beta N17. This was not a reflection of higher immunological levels of adenylate cyclase, indicating that the higher basal formation of GSAC probably reflects empty-receptor activation of Gs. This higher basal specific [3H]forskolin binding was partially reversed by propranolol. The addition of the opioid peptide D-Ala-D-Leu-enkephalin to NG108-15 cells did not reduce iloprost-stimulated [3H]forskolin binding even though this peptide inhibits stimulated adenylate cyclase activity by activation of a delta opioid receptor.

scholarly journals The role of GTP in prostaglandin E1 stimulation of adenylate cyclase in platelet membranes

1983 ◽  
Vol 214 (1) ◽  
pp. 231-234 ◽  
Author(s):  
J M Stein ◽  
B R Martin
Keyword(s):  
Adenylate Cyclase ◽  
Prostaglandin E1 ◽  
Platelet Membrane ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent ◽  
Stimulation Of

Adenylate cyclase activity in platelet membrane preparations was measured in the presence of prostaglandin E1 (PGE1), GTP and a non-hydrolysable analogue of GDP, guanosine 5′-[beta-thio]diphosphate (GDP[beta S]). A dose-dependent inhibition of adenylate cyclase by GDP[beta S] was observed that could be reversed either by adding increased amounts of GTP or of PGE1.

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