Activation of P2X7 receptors induces CCL3 production in microglial cells through transcription factor NFAT
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Published on: May 31, 2018
Ayako Kataoka1, Hidetoshi Tozaki-Saitoh, Yui Koga
1Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi, Fukuoka, Japan.
Abstract:
Microglia are implicated as a source of diverse proinflammatory factors in the CNS. Extracellular nucleotides are well known to be potent activators of glial cells and trigger the release of cytokines from microglia through purinergic receptors. However, little is known about the role of purinoceptors in microglial chemokine release. In this study, we found that high concentrations of ATP evoked release of CC-chemokine ligand 3 (CCL3)/macrophage inflammatory protein-1alpha from MG-5 cells, a mouse microglial cell line, and rapid up-regulation of CCL3 mRNA was elicited within 30 min of ATP stimulation. The release of CCL3 was also stimulated by 2'- and 3'-O-(4-benzoylbenzoyl) ATP, an agonist of P2X(7) receptors. Brilliant Blue G, an antagonist of P2X(7) receptors, strongly inhibited this ATP-induced CCL3 release. Similar pharmacological profile was observed in primary microglia. In MG-5 cells, ATP caused de-phosphorylation and nuclear translocation of the transcription factor nuclear factor of activated T cells (NFAT). ATP-induced NFAT de-phosphorylation was also dependent on P2X(7) receptor activation. Furthermore, ATP-induced CCL3 release and production were prevented by a selective inhibitor of NFAT. Taken together, the results of this study demonstrate an involvement of NFAT in the mechanism underlying P2X(7) receptor-mediated CCL3 release.
Insights
Extracellular ATP (adenosine triphosphate) triggers microglia to release CC-chemokine ligand 3 (CCL3) via P2X(7) receptors and NFAT activation. This finding clarifies a key mechanism in neuroinflammation.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are key immune cells in the central nervous system (CNS).
- Extracellular nucleotides, like ATP, activate glial cells via purinergic receptors.
- The role of purinoceptors in microglial chemokine release is not well understood.
Purpose of the Study:
- To investigate the role of purinoceptors in microglial chemokine release.
- To elucidate the signaling pathway involved in ATP-induced chemokine release from microglia.
Main Methods:
- Used MG-5 microglial cell line and primary microglia.
- Stimulated cells with ATP and its analogs.
- Utilized P2X(7) receptor agonists and antagonists (Brilliant Blue G).
- Assessed CCL3 release and mRNA expression.
- Investigated nuclear factor of activated T cells (NFAT) de-phosphorylation and translocation.
Main Results:
- High ATP concentrations induced CCL3 release and CCL3 mRNA up-regulation in MG-5 cells.
- ATP-induced CCL3 release was mediated by P2X(7) receptors, as shown by agonist and antagonist studies.
- ATP stimulation led to NFAT de-phosphorylation and nuclear translocation, dependent on P2X(7) receptor activation.
- Inhibition of NFAT blocked ATP-induced CCL3 release and production.
Conclusions:
- P2X(7) receptors play a crucial role in ATP-mediated CCL3 release from microglia.
- NFAT is a key transcription factor involved in the P2X(7) receptor-dependent release of CCL3.
- This study reveals a signaling pathway linking purinergic receptors to chemokine production in microglia, relevant to neuroinflammation.
