Adenylate cyclase blockers dissociate PTH-stimulated bone resorption from cAMP production

1990 ◽  
Vol 258 (4) ◽  
pp. E708-E714 ◽  
Author(s):  
I. R. Reid ◽  
C. Lowe ◽  
J. Cornish ◽  
D. H. Gray ◽  
S. J. Skinner
Keyword(s):  
Bone Resorption ◽  
Adenylate Cyclase ◽  
Camp Production ◽  
Organ Cultures ◽  
Maximal Inhibition ◽  
Dihydroxyvitamin D3 ◽  
Messenger System ◽  
45Ca Release ◽  
Stimulation Of

It is uncertain whether adenosine 3',5'-cyclic monophosphate (cAMP) or the inositol-calcium pathway mediates the stimulation of bone resorption by parathyroid hormone (PTH). Incubation of bone organ cultures with cAMP analogues and forskolin has not resolved this question because of the cellular inhomogeneity of bone and the consequent presence of adenylate cyclase-linked receptors for both PTH and calcitonin, hormones with opposite effects on bone resorption. We have used two new inhibitors of adenylate cyclase, 9-(tetrahydro-2-furyl)adenine (SQ 22536) and 2',5'-dideoxyadenosine (DDA), to directly reassess the role of cAMP in PTH-stimulated osteolysis. SQ 22536 (0.01-1.0 mM) and DDA (0.01-1.0 mM) completely blocked PTH stimulation of cAMP production measured in the absence of a phosphodiesterase blocker. In the presence of 1 mM 3-isobutyl-1-methylxanthine, half-maximal inhibition of PTH-induced cAMP production occurred with 0.2 mM SQ and 0.1 mM DDA, respectively. These concentrations of SQ and DDA had no effect on PTH-stimulated 45Ca release from calvaria, although both agents inhibited bone resorption when present at concentrations of 1-2 mM. At these levels, SQ and DDA caused equivalent inhibition of 45Ca release stimulated by 1,25-dihydroxyvitamin D3 but did not affect basal 45Ca release or [3H]-phenylalanine incorporation. It is concluded that substantial blockade of PTH-induced cAMP production does not affect this hormone's stimulation of bone resorption, which is therefore likely to be mediated by another intracellular messenger system, possibly calcium. In millimolar concentrations, SQ and DDA appear to be nonspecific blockers of osteoclastic bone resorption.

Differential effects of glucocorticoids on bone resorption in neonatal mouse calvariae stimulated by peptide and steroid-like hormones

1997 ◽  
Vol 155 (3) ◽  
pp. 513-521 ◽  
Author(s):  
HH Conaway ◽  
D Grigorie ◽  
UH Lerner
Keyword(s):  
Bone Resorption ◽  
Vitamin D3 ◽  
Neonatal Mouse ◽  
Receptor Interaction ◽  
Differential Effects ◽  
All Trans Retinoic Acid ◽  
45Ca Release ◽  
Stimulation Of

Differential effects on in vitro bone resorption were observed when the glucocorticoids, hydrocortisone and dexamethasone, were added to neonatal mouse calvariae treated with either parathyroid hormone (PTH), 1,25(OH)2-vitamin D3, all trans-retinoic acid (t-RA), or prostaglandin E2 (PGE2). Bone resorption was assessed by analyzing either the release of 45Ca from [45Ca]CaCl2 prelabeled calvarial bones or the release of 3H from [3H]proline prelabeled calvariae. At PGE2 concentrations of 3 x 10(-8) and 3 x 10(-7) mol/l, co-treatment with either 10(-6) mol/l dexamethasone or 10(-6) mol/l hydrocortisone caused additive 45Ca release from neonatal mouse calvariae. In contrast, synergistic release from mouse calvarial bones of both 45Ca and 3H was found after either 10(-6) mol/l hydrocortisone or 10(-6) mol/l dexamethasone was combined with 3 x 10(-11) mol/l PTH treatment for 120 h. Dose-response studies indicated that the synergistic stimulation of 45Ca release from neonatal mouse calvariae by glucocorticoids and PTH could be elicited at glucocorticoid concentrations of 10(-8) to 10(-6) mol/l and at PTH concentrations of 10(-11) to 10(-9) mol/l. Progesterone and RU 38486 (a derivative of 19-nortestosterone with antiglucocorticoid activity) blocked the synergism noted with glucocorticoid and PTH co-treatment, suggesting that interaction between the steroids and PTH was dependent on glucocorticoid receptor interaction. Addition of either 10(-6) mol/l hydrocortisone or 10(-6) mol/l dexamethasone to neonatal mouse calvariae treated with 1,25(OH)2-vitamin D3 (10(-11) and 10(-10) mol/l) also resulted in synergistic stimulation of 45Ca release. In contrast to these observations, the stimulatory effect of t-RA (10(-8) mol/l) on 45Ca release from calvarial bones was abolished in the presence of 10(-6) mol/l dexamethasone. These results suggest that an important role of glucocorticoids may be to synergistically potentiate bone resorption stimulated by PTH and 1,25(OH)2-vitamin D3, but indicate an opposing interaction between the glucocorticoids and bone resorptive retinoids.

Interaction between amrinone and parathyroid hormone on bone in culture

1982 ◽  
Vol 243 (6) ◽  
pp. E499-E504
Author(s):  
N. S. Krieger ◽  
P. H. Stern
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Direct Interaction ◽  
Inhibitory Effects ◽  
Dihydroxyvitamin D3 ◽  
Basal Bone ◽  
Cardiotonic Agent ◽  
Neonatal Mouse Calvaria ◽  
Dose Dependent ◽  
Stimulation Of

The cardiotonic agent amrinone has been postulated to directly affect Na-Ca exchange. Because stimulated bone resorption has been proposed to require Na-Ca exchange, we examined the effects of amrinone on bone. Amrinone inhibited release of Ca from neonatal mouse calvaria in organ culture stimulated by parathyroid hormone (PTH), 1,25-dihydroxyvitamin d3, or prostaglandin E2. Inhibition was dose dependent and maximal at 2 X 10(-4) M. The effect of amrinone differed from the inhibitory effects of calcitonin, ouabain, or nigericin in that 1) 6-h exposure to amrinone alone prevented the effect of subsequently added PTH; 2) amrinone was only partially effective if added after resorption was initiated by 24-h treatment with PTH; 3) coincubation with amrinone and PTH during the first 48 h of culture allowed for a response to PTH after amrinone was removed; no such protection by a stimulator occurred with ouabain or nigericin. Also submaximal concentrations of amrinone plus calcitonin, ouabain, or nigericin gave greater than additive inhibition of Ca release. Amrinone had no effect on basal bone cAMP or on the acute stimulation of cAMP by PTH. The results suggest that amrinone could have a more direct interaction with the pathway involved in stimulated bone resorption than the other inhibitors.

The biological activity of glucagon–phospholipid complexes

1983 ◽  
Vol 61 (7) ◽  
pp. 688-691 ◽  
Author(s):  
J. J. Liepnieks ◽  
P. Stoskopf ◽  
E. A. Carrey ◽  
C. Prosser ◽  
R. M. Epand
Keyword(s):  
Biological Activity ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Bovine Brain ◽  
Water Soluble ◽  
Dipalmitoyl Phosphatidylcholine ◽  
Dimyristoyl Phosphatidylcholine ◽  
Lipoprotein Complex ◽  
Stimulation Of

Glucagon can form water-soluble complexes with phospholipids. The incorporation of glucagon into these lipoprotein particles reduces the biological activity of the hormone. The effect is observed only at temperatures below the phase transition temperature of the phospholipid and results in a decreased stimulation of the adenylate cyclase of rat liver plasma membranes by the lipoprotein complex as compared with the hormone in free solution. Two- to five-fold higher concentrations of glucagon are required for half-maximal stimulation of adenylate cyclase when the hormone is complexed with dimyristoyl phosphatidylcholine, dipalmitoyl phosphatidylcholine, or bovine brain sphingomyelin. A possible role of lipoprotein-associated hormones in the development of insulin resistance is discussed.

scholarly journals G protein-regulated endocytic trafficking of adenylyl cyclase type 9

2020 ◽  
Author(s):  
André M. Lazar ◽  
Roshanak Irannejad ◽  
Tanya A. Baldwin ◽  
Aparna A. Sundaram ◽  
J. Silvio Gutkind ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Adenylyl Cyclase ◽  
G Protein ◽  
Subcellular Location ◽  
Endocytic Pathway ◽  
Heterotrimeric G Proteins ◽  
Camp Production ◽  
Stimulation Of

SummaryGPCRs are increasingly recognized to initiate signaling via heterotrimeric G proteins as they move through the endocytic network, but little is known about how relevant G protein effectors are localized. Here we report dynamic trafficking of adenylyl cyclase type 9 (AC9) from the plasma membrane to endosomes, while adenylyl cyclase type 1 (AC1) remains in the plasma membrane, and stimulation of AC9 trafficking by ligand-induced activation of Gs-coupled GPCRs or Gs. AC9 transits a similar dynamin-dependent early endocytic pathway as activated GPCRs but, in contrast to GPCR trafficking which is regulated by β-arrestin but not Gs, AC9 trafficking is regulated by Gs but not β-arrestin. We also show that AC9, but not AC1, contributes to cAMP production from endosomes. These results reveal dynamic and isoform-specific trafficking of adenylyl cyclase in the endocytic network, and a discrete role of a heterotrimeric G protein in controlling subcellular location of a relevant effector.

1,25-Dihydroxyvitamin D3 and TPA activate phospholipase D in Caco-2 cells: role of PKC-α

1999 ◽  
Vol 276 (4) ◽  
pp. G993-G1004 ◽  
Author(s):  
Sharad Khare ◽  
Marc Bissonnette ◽  
Beth Scaglione-Sewell ◽  
Ramesh K. Wali ◽  
Michael D. Sitrin ◽  
...  
Keyword(s):  
Phospholipase D ◽  
Dihydroxyvitamin D3 ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Gf 109203X ◽  
Pkc Β ◽  
Stimulation Of

1,25-Dihydroxyvitamin D3[1,25(OH)2D3] and 12- O-tetradecanoylphorbol 13-acetate (TPA) both activated phospholipase D (PLD) in Caco-2 cells. GF-109203x, an inhibitor of protein kinase C (PKC) isoforms, inhibited this activation by both of these agonists. 1,25(OH)2D3activated PKC-α, but not PKC-β1, -βII, -δ, or -ζ, whereas TPA activated PKC-α, -β1, and -δ. Chronic treatment with TPA (1 μM, 24 h) significantly reduced the expression of PKC-α, -βI, and -δ and markedly reduced the ability of 1,25(OH)2D3or TPA to acutely stimulate PLD. Removal of Ca2+ from the medium, as well as preincubation of cells with Gö-6976, an inhibitor of Ca2+-dependent PKC isoforms, significantly reduced the stimulation of PLD by 1,25(OH)2D3or TPA. Treatment with 12-deoxyphorbol-13-phenylacetate-20-acetate, which specifically activates PKC-βI and -βII, however, failed to stimulate PLD. In addition, the activation of PLD by 1,25(OH)2D3or TPA was markedly reduced or accentuated in stably transfected cells with inhibited or amplified PKC-α expression, respectively. Taken together, these observations indicate that PKC-α is intimately involved in the stimulation of PLD in Caco-2 cells by 1,25(OH)2D3or TPA.

scholarly journals Role of prostaglandins in hypoxia-stimulated erythropoietin production

1985 ◽  
Vol 249 (1) ◽  
pp. C3-C8 ◽  
Author(s):  
A. Kurtz ◽  
W. Jelkmann ◽  
J. Pfeilschifter ◽  
C. Bauer
Keyword(s):  
Arachidonic Acid ◽  
Adenylate Cyclase ◽  
Cell Cultures ◽  
Mesangial Cells ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Cyclooxygenase Inhibitor ◽  
Erythropoietin Production ◽  
Stimulation Of

The role of prostaglandins in the mediation of hypoxia-stimulated erythropoietin (Ep) production by cultured rat renal mesangial cells was examined. It was found that an increase in prostaglandin E2 (PGE2) production accompanied the rise in Ep due to hypoxia (2% O2). The hypoxia-stimulated increase in Ep production was abolished in the presence of the cyclooxygenase inhibitor indomethacin (10(-5) M). When PGE2 (10(-6) M was added simultaneously with indomethacin, however, no diminution in hypoxia-stimulated Ep production was observed. Addition of arachidonic acid (AA, 10(-5) M), PGE2 (10(-6) M), or PGI2 (10(-4) M) enhanced Ep production under normoxic conditions (20% O2), while PGF2 alpha (10(-6) M) had no effect on Ep production. AA, PGE2, and PGI2 were found to stimulate adenosine 3',5'-cyclic monophosphate formation by the cultured mesangial cells. Enhancement of adenylate cyclase activity by forskolin (10(-5) M) also increased Ep production in the cell cultures. Our results suggest that hypoxia-stimulated Ep production by cultured mesangial cells is mediated by prostaglandins with subsequent stimulation of adenylate cyclase activity.

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.

Parathyroid hormone sensitizes long bones to the stimulation of bone resorption by 1,25-dihydroxyvitamin D3

2009 ◽  
Vol 7 (3) ◽  
pp. 303-309 ◽  
Author(s):  
J. P. T. M. van Leeuwen ◽  
J. C. Birkenhäger ◽  
M. P. Bos ◽  
G. J. C. M. van der Bemd ◽  
M. P. M. Herrmann-Erlee ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Long Bones ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3 ◽  
Stimulation Of
Sign in / Sign up

Export Citation Format

Share Document