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Regulation of purinergic signaling by prostaglandin E2 in murine macrophages
1Laboratory of Pharmacology, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki-shi, Gunma, Japan.
Abstract:
Extracellular nucleotides are primary signals for tissue injury, acting together with various chemical mediators such as prostanoids at the inflammatory site. We investigated whether prostaglandin E2 (PGE2) affects purinergic signaling in murine J774 macrophages. J774 cells expressed four different purinoceptor mRNAs: the ionotropic P2X4 and P2X7 receptors and G-protein-coupled P2Y2 and P2Y6 receptors. Functional responses mediated by these purinoceptor subtypes were confirmed by measurement of intracellular Ca2+ concentration ([Ca2+]i) in fura-2-loaded cells. Thus, low concentrations (10 microM) of ATP (P2Y2 agonist) and UDP (P2Y6 agonist) evoked Ca2+ transient in a phospholipase C (PLC)-dependent manner, whereas the P2X7 agonist benzoylbenzoyl-ATP (BzATP, 500 microM) caused a sustained rise in [Ca2+]i. Furthermore, ivermectin, an activator of the P2X4-receptor channel, enhanced the ATP-induced [Ca2+]i elevation. PGE2 inhibited ATP- and UDP-induced [Ca2+]i elevation, without affecting the BzATP-induced sustained [Ca2+]i elevation. Stimulation of J774 cells by UDP or BzATP increased the production of macrophage inflammatory peptide-alpha (MIP-alpha). PGE2 abolished the UDP-induced MIP-alpha production, but not the BzATP-induced one. These results demonstrate that purinergic signalings in macrophages were regulated by PGE2 in a subtype-specific manner. The different inhibitory effects on distinct purinoceptor functions may be related to the anti-inflammatory property of PGE2.
Insights
Prostaglandin E2 (PGE2) selectively inhibits specific purinergic signaling pathways in macrophages, impacting inflammatory responses. This research reveals subtype-specific regulation of macrophage purinergic signaling by PGE2.
Area of Science:
- Immunology
- Cell Biology
- Pharmacology
Background:
- Extracellular nucleotides act as key signaling molecules during tissue injury and inflammation.
- Prostaglandin E2 (PGE2) is a prostanoid mediator found at inflammatory sites.
- Macrophages play a crucial role in inflammatory processes.
Purpose of the Study:
- To investigate the effect of prostaglandin E2 (PGE2) on purinergic signaling in murine J774 macrophages.
- To determine the subtype-specific regulation of purinergic receptors by PGE2.
- To elucidate the role of PGE2 in modulating macrophage inflammatory mediator production.
Main Methods:
- J774 macrophages were analyzed for purinoceptor mRNA expression (P2X4, P2X7, P2Y2, P2Y6).
- Intracellular calcium ([Ca2+]i) concentration was measured using fura-2 to assess functional purinoceptor responses.
- Macrophage inflammatory peptide-alpha (MIP-alpha) production was quantified following stimulation.
Main Results:
- PGE2 inhibited ATP- and UDP-induced calcium ([Ca2+]i) elevation, but not BzATP-induced elevation.
- PGE2 abolished UDP-induced MIP-alpha production, while not affecting BzATP-induced production.
- These findings indicate subtype-specific regulation of purinergic signaling by PGE2 in macrophages.
Conclusions:
- Prostaglandin E2 (PGE2) differentially regulates purinergic signaling pathways in macrophages.
- The selective inhibition of distinct purinoceptor functions by PGE2 may contribute to its anti-inflammatory properties.
- Understanding these interactions is crucial for developing targeted anti-inflammatory therapies.
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