Related Experiment Videos
Mechanisms underlying extracellular ATP-evoked interleukin-6 release in mouse microglial cell line, MG-5
Y Shigemoto-Mogami1, S Koizumi, M Tsuda
1Division of Pharmacology, National Institute of Health Sciences, Setagaya, Tokyo, Japan.
Abstract:
Microglia play various important roles in the CNS via the synthesis of cytokines. The ATP-evoked production of interleukin-6 (IL-6) and its intracellular signals were examined using a mouse microglial cell line, MG-5. ATP, but not its metabolites, produced IL-6 in a concentration-dependent manner. Although ATP activated two mitogen-activated protein kinases, i.e. p38 and extracellular signal-regulated protein kinase, only p38 was involved in the IL-6 induction. However, the activation of p38 was not sufficient for the IL-6 induction because 2'- and 3'-O-(4-benzoylbenzoyl) ATP, an agonist to P2X7 receptors, failed to produce IL-6 despite the fact that it activated p38. Unlike in other cytokines in microglial cells, P2Y rather than P2X7 receptors seem to have a major role in the IL-6 production by the cells. The ATP-evoked IL-6 production was attenuated by Gö6976, an inhibitor of Ca(2+)-dependent protein kinase C (PKC). The P2Y receptor responsible for these responses was insensitive to pertussis toxin (PTX) and was linked to phospholipase C. Taken together, ATP acting on PTX-insensitive P2Y receptors activates p38 and Ca(2+)-dependent PKC, thereby resulting in the mRNA expression and release of IL-6 in MG-5. This is a novel pathway for the induction of cytokines in microglia.
Insights
Adenosine triphosphate (ATP) triggers interleukin-6 (IL-6) release from microglia via P2Y receptors, activating p38 and protein kinase C (PKC). This reveals a new pathway for cytokine induction in the central nervous system (CNS).
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are key immune cells in the central nervous system (CNS).
- Microglia synthesize cytokines, crucial signaling molecules.
- Interleukin-6 (IL-6) is an important cytokine with diverse roles.
Purpose of the Study:
- To investigate the mechanisms of ATP-evoked IL-6 production in microglia.
- To identify the specific receptors and signaling pathways involved in IL-6 induction.
Main Methods:
- Utilized a mouse microglial cell line (MG-5).
- Examined the effects of ATP and its analogs on IL-6 production.
- Assessed the activation of mitogen-activated protein kinases (MAPKs) and protein kinase C (PKC).
- Investigated the roles of P2X7 and P2Y receptors using specific agonists and inhibitors.
Main Results:
- ATP induced IL-6 production in a concentration-dependent manner.
- Activation of p38 MAPK, but not ERK, was involved in IL-6 induction.
- P2Y receptors, not P2X7 receptors, were primarily responsible for ATP-evoked IL-6 release.
- Inhibition of Ca(2+)-dependent PKC attenuated IL-6 production.
- The identified P2Y receptor was pertussis toxin (PTX)-insensitive and linked to phospholipase C.
Conclusions:
- ATP activates PTX-insensitive P2Y receptors on microglia.
- This activation leads to p38 MAPK and Ca(2+)-dependent PKC activation.
- A novel signaling pathway involving P2Y receptors, p38, and PKC mediates IL-6 mRNA expression and release in microglia.