TRPM2 contributes to LPS/IFNγ-induced production of nitric oxide via the p38/JNK pathway in microglia.

Abstract

Microglia are immune cells that maintain brain homeostasis at a resting state by surveying the environment and engulfing debris. However, in some pathological conditions, microglia can produce neurotoxic factors such as pro-inflammatory cytokines and nitric oxide (NO) that lead to neuronal degeneration. Inflammation-induced calcium (Ca(2+)) signaling is thought to underlie this abnormal activation of microglia, but the mechanisms are still obscure. We previously showed that combined application of lipopolysaccharide and interferon γ (LPS/IFNγ) induced-production of NO in microglia from wild-type (WT) mice is significantly reduced in microglia from transient receptor potential melastatin 2 (TRPM2)-knockout (KO) mice. Here, we found that LPS/IFNγ produced a late-onset Ca(2+) signaling in WT microglia, which was abolished by application of the NADPH oxidase inhibitor diphenylene iodonium (DPI) and ML-171. In addition, pharmacological blockade or gene deletion of TRPM2 channel in microglia did not show this Ca(2+) signaling. Furthermore, pharmacological manipulation and Western blotting revealed that Ca(2+) mobilization, the proline-rich tyrosine kinase 2 (Pyk2), p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun NH2-terminal kinase (JNK) contributed to TRPM2-mediated LPS/IFNγ-induced activation, while the extracellular signal-regulated protein kinase (ERK) did not. These results suggest that LPS/IFNγ activates TRPM2-mediated Ca(2+) signaling, which in turn increases downstream p38 MAPK and JNK signaling and results in increased NO production in microglia.

• Authors: Takahito Miyake, Hisashi Shirakawa, Ayaka Kusano, Shinya Sakimoto, Masakazu Konno, Takayuki Nakagawa, Yasuo Mori, Shuji Kaneko
• Journal: Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 444 Issue 2 Pg. 212-7 (Feb 07 2014) ISSN: 1090-2104 [Electronic] United States
• PMID: 24462864 (Publication Type: Journal Article)
• Copyright: Copyright © 2014 Elsevier Inc. All rights reserved.

Chemical References

• Chelating Agents
• Enzyme Inhibitors
• Lipopolysaccharides
• Nitriles
• TRPM Cation Channels
• TRPM2 protein, mouse
• Tyrphostins
• Nitric Oxide
• SF 6847
• Egtazic Acid
• Miconazole
• Interferon-gamma
• NADPH Oxidases
• Focal Adhesion Kinase 2
• Ptk2b protein, mouse
• JNK Mitogen-Activated Protein Kinases
• p38 Mitogen-Activated Protein Kinases
• 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
• Calcium

Topics

• Animals
• Blotting, Western
• Calcium (metabolism)
• Cells, Cultured
• Chelating Agents (pharmacology)
• Egtazic Acid (analogs & derivatives, pharmacology)
• Enzyme Inhibitors (pharmacology)
• Focal Adhesion Kinase 2 (antagonists & inhibitors, metabolism)
• Interferon-gamma (pharmacology)
• JNK Mitogen-Activated Protein Kinases (antagonists & inhibitors, metabolism)
• Lipopolysaccharides (pharmacology)
• MAP Kinase Signaling System (drug effects)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Miconazole (pharmacology)
• Microglia (drug effects, metabolism)
• NADPH Oxidases (antagonists & inhibitors, metabolism)
• Nitric Oxide (biosynthesis)
• Nitriles
• TRPM Cation Channels (antagonists & inhibitors, genetics, metabolism)
• Tyrphostins (pharmacology)
• p38 Mitogen-Activated Protein Kinases (antagonists & inhibitors, metabolism)