Adenylate cyclase activity in rat corpora lutea evidence for a rapid development of the regulatory Ns-protein

1986 ◽  
Vol 112 (4) ◽  
pp. 565-570 ◽  
Author(s):  
Sten Rosberg ◽  
Ensio Norjavaara ◽  
Monica Sender Baum ◽  
Iqbal Khan
Keyword(s):  
Adenylate Cyclase ◽  
Rapid Development ◽  
Close Correlation ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Corpora Lutea ◽  
Constant Amount ◽  
Adrenergic Response ◽  
Catalytic Unit ◽  
Serum Gonadotropin

Abstract. Adenylate cyclase activity was studied in membranes from isolated corpora lutea of defined ages obtained from pregnant mare's serum gonadotropin treated rats and the effects of luteinizing hormone (LH), isoproterenol, guanylylimidodiphosphate (Gpp (NH)p), fluoride and forskolin were compared. The effect of LH on adenylate cyclase activity increased with the luteal age up to nine days of age, while the effect of isoproterenol increased dramatically during the first days, reaching a maximum at 2–3 days of age and then declined. Forskolin potentiated the effects of both LH and isoproterenol without affecting the patterns of age-dependency. The effect of forskolin itself was fairly constant during the luteal phase, indicating a relatively constant amount of the catalytic unit in the corpus luteum. The effects of fluoride and Gpp(NH)p on the other hand increased markedly during the first days and then remained constant for the rest of the period studied. These results suggest that the regulatory Ns-protein develops during the first days of luteal life. It is speculated that the close correlation between the development of β-adrenergic response and the development of Ns-protein are causally related.

Studies of the luteinization process in the rat: follicular and luteal adenylate cyclase responsiveness to catecholamines

1987 ◽  
Vol 114 (2) ◽  
pp. 171-177 ◽  
Author(s):  
Gunnar Selstam ◽  
Ensio Norjavaara ◽  
Sten Rosberg ◽  
Knut Nordenström ◽  
Jan-Erik Damber ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Luteal Phase ◽  
Follicular Phase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Significant Response ◽  
Corpora Lutea ◽  
Preovulatory Follicles ◽  
The Subject ◽  
Catecholamine Responsiveness

Abstract. The subject of the study was the development of follicular and luteal catecholamine responsiveness during the periovulatory period. Follicles and corpora lutea and granulosa cells were obtained from the PMSG ovulatory model and adenylate cyclase activity measured in membrane fractions. In the earlier part of the follicular phase (48 h and 26 h before ovulation) no response to noradrenalin on follicular and granulosa cell adenylate cyclase activity was seen. A small but significant response to noradrenalin was observed from 18 h before until 3 h after ovulation. The response to noradrenalin on luteal adenylate cyclase activity increased markedly with time and reached a maximum 39–57 h after ovulation. After this time the luteal response to noradrenalin decreased with luteal age. The effect of LH was less than that of noradrenalin during the early luteal phase, and in contrast to noradrenalin, increased with luteal age. The combined effects of LH and noradrenalin were not additive. In order to test whether gonadotropins could induce a noradrenalin response, injections of LH and FSH were given to the animals two days before ovulation. LH, but not FSH, induced a small but significant response to noradrenalin 16 h later. The present investigation has shown that ovarian responsiveness to catecholamines appears in preovulatory follicles followed by a marked increase in luteal catecholamine responsiveness. This development could at least partly occur under the influence of LH.

Catecholamine content and adenylate cyclase activity in corpora lutea of different ages of the PMSG-treated immature rat

1987 ◽  
Vol 53 (3) ◽  
pp. 155-160 ◽  
Author(s):  
Gunnar Selstam ◽  
Ensio Norjavaara ◽  
Sten Rosberg ◽  
Iqbal Khan ◽  
Bertil Hamberger ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Corpora Lutea ◽  
Immature Rat ◽  
Catecholamine Content ◽  
Different Ages

A cytosolic peptide potentiates the GTP effect on beta-adrenergic response of adenylate cyclase

1994 ◽  
Vol 266 (2) ◽  
pp. C498-C507
Author(s):  
K. Omori ◽  
K. Kitagawa ◽  
K. Omori ◽  
T. Yasukura ◽  
T. Uriu ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Complex Form ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Beta Adrenergic ◽  
Adrenergic Response ◽  
Peptide Component ◽  
Relative Molecular Weight ◽  
Guanine Nucleotide Binding ◽  
Competition Curve

A cytosolic peptide-GTP complex that stimulates l-isoproterenol-responsive adenylate cyclase activity was identified in the rat liver. The peptide component was purified and characterized with regard to its interaction with GTP. The peptide was isolated as a complex form with GTP on a Sephadex G-25 column in 1 mM NaHCO3, and was purified as a dissociated form, with relative molecular weight (M(r)) approximately 3,000 and GTP-binding ability, in 200 mM ammonium acetate. The purified peptide alone displayed little stimulatory effect on adenylate cyclase activity, but its reassociated form with GTP clearly enhanced the effect of GTP on the enzyme activity. The isoproterenol competition curve using l-[3H]dihydroalprenolol as an antagonist ligand shifted to lower affinity by the addition of the peptide reassociated with GTP (16.5-fold shift), whereas the same concentration of GTP (1 microM) or the peptide alone had little or no effect (1.5- or 0.9-fold shift, respectively). Furthermore, the peptide enhanced the GTP effect in response to l-isoproterenol but not to glucagon, prostaglandin E1, or fluoride. These results suggest that the cytosolic peptide potentiates the effect of GTP on the agonist-beta-adrenergic receptor-stimulatory guanine nucleotide-binding regulatory component of the adenylate cyclase ternary complex.

scholarly journals The local anaesthetic benzyl alcohol attenuates the α2-adrenoceptor-mediated inhibition of human platelet adenylate cyclase activity when stimulated by prostaglandin E1, but not that stimulated by forskolin

1989 ◽  
Vol 264 (2) ◽  
pp. 483-488 ◽  
Author(s):  
S Spence ◽  
M D Houslay
Keyword(s):  
Adenylate Cyclase ◽  
Benzyl Alcohol ◽  
Inhibitory Action ◽  
Prostaglandin E1 ◽  
Regulatory Protein ◽  
Inhibitory Response ◽  
Dose Effect ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Catalytic Unit

Treatment of human platelets with concentrations of benzyl alcohol up to 50 mM augmented adenylate cyclase activity when it was assayed in the basal state and when stimulated by prostaglandin E1 (PGE1), isoprenaline or NaF. Benzyl alcohol antagonized the stimulatory effect exerted on the catalytic unit of adenylate cyclase by the diterpene forskolin. Benzyl alcohol did not modify the magnitude of the inhibitory response when the catalytic unit of adenylate cyclase was inhibited by using either low concentrations of guanosine 5′-[beta gamma-imido]triphosphate, which acts selectively on the inhibitory guanine nucleotide-regulatory protein Gi, or during alpha 2-adrenoceptor occupancy, by using adrenaline (+ propranolol). Some 34% of the potent inhibitory action of adrenaline on PGE1-stimulated adenylate cyclase was obliterated in a dose-dependent fashion (concn. giving 50% inhibition = 12.5 mM) by benzyl alcohol, with the residual inhibitory action being apparently resistant to the action of benzyl alcohol at concentrations up to 50 mM. Treatment of membranes with benzyl alcohol did not lead to the release of either the alpha-subunit of Gi or G-protein subunits. The alpha 2-adrenoceptor-mediated inhibition of adenylate cyclase was abolished when assays were performed in the presence of Mn2+ rather than Mg2+ and, under such conditions, dose-effect curves for the action of benzyl alcohol on PGE1-stimulated adenylate cyclase activity were similar whether or not adrenaline (+propranolol) was present. We suggest that (i) alpha 2-adrenoceptor- and Gi-mediated inhibition of PGE1-stimulated adenylate cyclase may have two components, one of which is sensitive to inhibition by benzyl alcohol, and (ii) the Gi-mediated inhibition of forskolin-stimulated adenylate cyclase exhibits predominantly the benzyl alcohol-insensitive component.

scholarly journals Regulation of basal adenylate cyclase activity in neuroblastoma × glioma hybrid, NG108-15, cells transfected to express the human β 2 adrenoceptor: evidence for empty receptor stimulation of the adenylate cyclase cascade

1994 ◽  
Vol 303 (3) ◽  
pp. 803-808 ◽  
Author(s):  
E J Adie ◽  
G Milligan
Keyword(s):  
Membrane Protein ◽  
Adenylate Cyclase ◽  
Receptor Activation ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Wild Type ◽  
Catalytic Unit ◽  
Beta 2 ◽  
Signalling Cascade ◽  
Stimulation Of

Clones of neuroblastoma x glioma hybrid, NH108-15, cells expressing differing levels of the human beta 2 adrenoceptor were isolated. Two clones were examined in detail, beta N22 which expressed some 4000 fmol/mg of membrane protein and clone beta N17 which expressed approx. 300 fmol/mg of membrane protein of the receptor. In beta N22 cells ‘basal’ adenylate cyclase activity measured in the presence of Mg2+ was significantly greater than that in wild-type NG108-15 or beta N17 cells. Both isoprenaline and iloprost were able to stimulate adenylate cyclase activity in each of beta N22 and beta N17 membranes. However, the EC50 for isoprenaline stimulation of adenylate cyclase in membranes of beta N22 cells (6 nM) was significantly lower than that in membranes of beta N17 cells (80 nM), whereas the EC50 for iloprost stimulation of adenylate cyclase (approx. 25 nM) was the same in the two clones and in parental NG108-15 cells. The high basal adenylate cyclase activity of beta N22 cell membranes was not a reflection of higher levels of expression of the adenylate cyclase catalytic unit, as adenylate cyclase activity measured in the presence of Mn2+ was equivalent in membranes of each of wild-type NG108-15 cells and clones beta N22 and beta N17. Basal adenylate cyclase activity measured in the presence of Mg2+ in clone beta N22 was significantly reduced, however, by the beta-receptor antagonist propranolol, whereas this agent was without effect on basal adenylate cyclase activity in membranes of wild-type NG108-15 cells. These data indicate that the elevated basal adenylate cyclase cascade in NG108-15 cells expressing high levels of the beta 2 adrenoceptor represents empty receptor activation of the signalling cascade.

scholarly journals Increase of adenylate cyclase catalytic-unit activity by dexamethasone in rat osteoblast-like cells

1986 ◽  
Vol 237 (2) ◽  
pp. 447-454 ◽  
Author(s):  
R Rizzoli ◽  
V von Tscharner ◽  
H Fleisch
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Bone Cells ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Guanine Nucleotide ◽  
Dexamethasone Treatment ◽  
Intact Cells ◽  
Catalytic Unit ◽  
Rat Osteoblast

Glucocorticoids are known to increase the cyclic AMP response to parathyroid hormone (PTH) in cultured bone organs or bone cells. Using the osteoblast-like cell line ROS 17/2.8, which possesses receptors for both PTH and glucocorticoids, we investigated which component of the complex hormone receptor-guanine nucleotide regulatory unit—adenylate cyclase was affected by dexamethasone treatment. In response to PTH, isoproterenol or forskolin, a compound that is supposed to act directly on the catalytic unit, cyclic AMP production by intact cells and adenylate cyclase activity in purified plasma membrane were markedly increased by dexamethasone. Whereas NaF, guanosine 5′-[beta gamma-imido]triphosphate and Mn/ stimulated adenylate cyclase activity were similarly enhanced in membranes isolated from glucocorticoid-treated cells, the activity of the stimulatory guanine nucleotide regulatory unit, as assessed by reconstitution into membranes from the CYC- clone, which is genetically devoid of this component, was not altered. Thus in osteoblast-like cells dexamethasone appears to increase cyclic AMP synthesis by influencing the catalytic unit. Moreover, since it has been reported that glucocorticoids may produce changes in cell calcium metabolism, we evaluated cytoplasmic free Ca2+ concentration ([Ca2+]i) and intracellular Ca2+ stores mobilizable by the bivalent-cationophore ionomycin, by using the intracellular fluorescent indicator Quin-2. The results indicated that dexamethasone treatment did not influence [Ca2+]i but markedly decreased ionomycin-releasable Ca2+ stores.

scholarly journals Guanosine 5′-triphosphate and guanosine 5′-[βγ-imido]triphosphate effect a collision coupling mechanism between the glucagon receptor and catalytic unit of adenylate cyclase

1980 ◽  
Vol 186 (3) ◽  
pp. 649-658 ◽  
Author(s):  
Miles D. Houslay ◽  
Irene Dipple ◽  
Keith R. F. Elliott
Keyword(s):  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Regulatory Protein ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Lipid Phase ◽  
Trypsin Treatment ◽  
Phase Separations ◽  
Catalytic Unit

1. GTP, but not p[NH]ppG (guanosine 5′-[βγ-imido]triphosphate), abolishes the sensitivity of glucagon-stimulated adenylate cyclase to the lipid-phase separations occurring in the outer half of the bilayer in liver plasma membranes from rat. 2. When either GTP or p[NH]ppG alone stimulate adenylate cyclase, the enzyme senses only those lipid-phase separations occurring in the inner half of the bilayer. 3. Trypsin treatment of intact hepatocytes has no effect on the basal, fluoride-, GTP- or p[NH]ppG-stimulated adenylate cyclase activity. However, 125I-labelled-glucagon specific binding decays with a half-life matching that of the decay of glucagon-stimulated adenylate cyclase activity. 4. When GTP or p[NH]ppG are added to assays of glucagon-stimulated activity, the half-life of the trypsin-mediated decay of activity is substantially increased and the decay plots are no longer first-order. 5. Trypsin treatment of purified rat liver plasma membranes abolishes basal and all ligand-stimulated adenylate cyclase activity, and 125I-labelled-glucagon specific binding. 6. Benzyl alcohol activates the GTP- and p[NH]ppG-stimulated activities in an identical fashion, whereas these activities are affected differently when glucagon is present in the assays. 7. We suggest that guanine nucleotides alter the mode of coupling between the receptor and catalytic unit. In the presence of glucagon and GTP, a complex of receptor, catalytic unit and nucleotide regulatory protein occurs as a transient intermediate, releasing a free unstable active catalytic unit. In the presence of p[NH]ppG and glucagon, the transient complex yields a relatively stable complex of the catalytic unit associated with a p[NH]ppG-bound nucleotide-regulatory protein.

The interaction of guanine nucleotides with the adenylate cyclase complex in white adipocyte membranes of lean and obese (ob/ob) mice

1984 ◽  
Vol 62 (9) ◽  
pp. 819-826 ◽  
Author(s):  
Nicole Bégin-Heick
Keyword(s):  
Adenylate Cyclase ◽  
Guanine Nucleotides ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Obese Mouse ◽  
Guanine Nucleotide ◽  
Obese Mice ◽  
White Adipocyte ◽  
Catalytic Unit ◽  
Maximal Activation

The ability of the guanine nucleotides (Gpp(NH)p and GTP-γ-S) and of fluoride to stimulate adenylate cyclase is equal in the white adipocyte of lean and ob/ob mice. This suggests that the interaction between the guanine nucleotide regulatory component (N) and the catalytic unit of adenylate cyclase is normal. In the membranes from obese mice, the addition of agonist did not diminish the concentration of guanine nucleotide required for half-maximal activation, as it did in membranes from lean mice, indicating that the interaction between the receptor and N may be altered in the obese mouse. GDP-β-S and GTP were found to be equally potent in inhibiting Gpp(NH)p-activated adenylate cyclase activity in both groups. Experiments with membranes loaded with or depleted of GDP showed that GDP did inhibit the activation of the cyclase under all conditions tested. Although depleting the membranes of obese mice of GDP improved their response to isoproterenol, it did not restore the response to levels seen in the membranes of lean mice. The data show that it is not likely the binding of GDP which limits cyclase stimulation by agonists. The defect must therefore reside in another property of N.

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