Related Experiment Videos
Activation of cyclic AMP-dependent protein kinase in macrophages
Abstract:
The activity of cyclic AMP-dependent protein kinase (cyclic AMP-PK) was significantly higher (P less than 0.001) in thioglycollate-elicited than in resident rat peritoneal macrophages. The activity ratio of the enzyme (its activity in the absence of added cyclic AMP divided by that in the presence of 5 microM cyclic AMP) was similar in the two cell types. The divalent ion ionophore A23187 induced a rapid increase in the activity ratio of cyclic AMP-PK in both macrophage types. This effect was blocked by pretreating the cells with indomethacin or aspirin (inhibitors of cyclo-oxygenase) and bromo-phenacyl bromide (an inhibitor of phospholipase A2), implicating the synthesis of a prostanoid as an intermediary step. Prostaglandin (PG) E2, 8-bromo cyclic AMP and cholera toxin, all of which inhibit chemiluminescence and/or PG formation in macrophages, increased the activity ratio of cyclic AMP-PK in these cells. We propose that the activation of cyclic AMP-PK plays a central role in the response of macrophages to both endogenously-generated and exogenously added PGE.
Insights
Cyclic AMP-dependent protein kinase (cyclic AMP-PK) activity is higher in elicited macrophages. Prostaglandin E2 and other agents activate cyclic AMP-PK, suggesting its central role in macrophage responses.
Area of Science:
- Immunology
- Cellular Biology
- Biochemistry
Background:
- Macrophages play a crucial role in immune responses.
- Cyclic AMP-dependent protein kinase (cyclic AMP-PK) is a key regulator of cellular processes.
Purpose of the Study:
- To investigate the activity and regulation of cyclic AMP-PK in rat peritoneal macrophages.
- To elucidate the role of cyclic AMP-PK in macrophage activation and response.
Main Methods:
- Measurement of cyclic AMP-PK activity in resident and thioglycollate-elicited rat peritoneal macrophages.
- Stimulation of macrophages with ionophore A23187, prostaglandin E2, 8-bromo cyclic AMP, and cholera toxin.
- Inhibition studies using indomethacin, aspirin, and bromo-phenacyl bromide.
Main Results:
- Cyclic AMP-PK activity was significantly higher in elicited macrophages compared to resident macrophages.
- A23187 induced a rapid increase in cyclic AMP-PK activity ratio, which was blocked by cyclo-oxygenase and phospholipase A2 inhibitors.
- Prostaglandin E2, 8-bromo cyclic AMP, and cholera toxin increased the cyclic AMP-PK activity ratio.
Conclusions:
- Prostanoid synthesis is implicated in the activation of cyclic AMP-PK by A23187.
- Activation of cyclic AMP-PK is central to macrophage responses to endogenous and exogenous prostaglandin E2.