Stimulation of reactive oxidant production in neutrophils by soluble and insoluble immune complexes occurs via different receptors/signal transduction systems

A wide spectrum of prostaglandins (PG) stimulate both the production of cyclic AMP and an increase in free cytosolic Ca2+ concentration [(Ca2+]i) in the osteogenic osteosarcoma cell line, UMR-106-01, which has characteristics compatible with osteoblasts. Using PG-stimulated determinations of the second messengers cyclic AMP and [Ca2+]i, a method for classification of PG receptors is presented. UMR-106-01 cells demonstrate three subclasses of PG receptors. One receptor interacts with PGF2 alpha, PGD2, and thromboxane B2 (TxB2) to increase [Ca2+]i. A second receptor binds PGE2, PGE1, PGI2, PGA2 and 6-oxo-PGF1 alpha to increase [Ca2+]i by stimulation of a second separate phospholipase C pool. A third receptor accepts PGE2, PGE1, PGA2, PGI2 and to a lesser extent PGF2 alpha, PGD2 and TxB2 to increase cyclic AMP. Such a classification system may be applicable to other cells responding to multiple PGs by inducing changes in cellular second messengers.

Download Full-text

Glucagon activates two distinct signal transduction systems in hepatocytes, which leads to the desensitization of G-protein-regulated adenylate cyclase, the phosphorylation and inactivation of Gi-2 and the phosphorylation and stimulation of a specific cyclic AMP phosphodiesterase

Activation and Desensitization of Transducing Pathways ◽

10.1007/978-3-642-83618-3_4 ◽

1990 ◽

pp. 63-83 ◽

Cited By ~ 1

Author(s):

Miles D. Houslay ◽

Mark Bushfield ◽

Elaine Kilgour ◽

Brian Lavan ◽

Suzanne Griffiths ◽

...

Keyword(s):

Signal Transduction ◽

Cyclic Amp ◽

Adenylate Cyclase ◽

G Protein ◽

Cyclic Amp Phosphodiesterase ◽

Stimulation Of ◽

Signal Transduction Systems

Download Full-text

Eicosapentaenoic Acid Interferes with U46619-Stimulated Formation of Inositol Phosphates in Washed Rabbit Platelets

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647129 ◽

1989 ◽

Vol 62 (04) ◽

pp. 1116-1120 ◽

Cited By ~ 9

Author(s):

N Chetty ◽

J D Vickers ◽

R L Kinlough-Rathbone ◽

M A Packham ◽

J F Mustard

Keyword(s):

Signal Transduction ◽

Fatty Acid Composition ◽

Eicosapentaenoic Acid ◽

Inositol Phosphates ◽

Inositol Phosphate ◽

Dense Granule ◽

Detectable Change ◽

Membrane Phospholipids ◽

Rabbit Platelets ◽

Stimulation Of

SummaryEicosapentaenoic acid (EPA) inhibits platelet responsiveness to aggregating agents. To investigate the reactions that are affected by EPA, we examined the effect of preincubating aspirintreated rabbit platelets with EPA on stimulation of inositol phosphate formation in response to the TXA2 analogue U46619. Stimulation of platelets with U46619 (0.5 μM) caused aggregation and slight release of dense granule contents; aggregation and release were inhibited by preincubation of the platelets with EPA (50 μM) for 1 h followed by washing to remove unincorporated EPA. Incubation with EPA (50 μM) for 1 h did not cause a detectable increase in the amount of EPA in the platelet phospholipids. When platelets were prelabelled with [3H]inositol stimulation with U46619 of control platelets that had not been incubated with EPA significantly increased the labelling of mos1tol phosphates. The increases in inositol phosphate labelling due to U46619 at 10 and 60 s were partially inhibited by premcubat10n of the platelets with 50 μM EPA. Since the activity of cyclo-oxygenase was blocked with aspirin, inhibition of inositol phosphate labelling in response to U46619 indicates either that there may be inhibition of signal transduction without a detectable change in the amount of EPA in platelet phospholipids, that changes in signal transduction require only minute changes in the fatty acid composition of membrane phospholipids, or that after a 1 h incubation with EPA, activation of phospholipase C is affected by a mechanism that is not directly related to incorporation of EPA.

Download Full-text