PNU-120596, a positive allosteric modulator of α7 nicotinic acetylcholine receptor, directly inhibits p38 MAPK

• Published in: Biochemical pharmacology Vol. 182; p. 114297
• Main Authors: Uwada, Junsuke, Nakazawa, Hitomi, Mikami, Daisuke, Islam, Mohammad Sayful, Muramatsu, Ikunobu, Taniguchi, Takanobu, Yazawa, Takashi
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.12.2020
• Subjects: Allosteric Regulation - drug effects; Allosteric Regulation - physiology; alpha7 Nicotinic Acetylcholine Receptor - agonists; alpha7 Nicotinic Acetylcholine Receptor - metabolism; Animals; Dose-Response Relationship, Drug; Humans; Inflammation; Isoxazoles - chemistry; Isoxazoles - pharmacology; MCF-7 Cells; Mice; Off-target; p38 MAPK; p38 Mitogen-Activated Protein Kinases - antagonists & inhibitors; p38 Mitogen-Activated Protein Kinases - metabolism; Phenylurea Compounds - chemistry; Phenylurea Compounds - pharmacology; PNU-120596; Positive allosteric modulator; Protein Kinase Inhibitors - chemistry; Protein Kinase Inhibitors - pharmacology; α7 nicotinic acetylcholine receptor; Positive allosteric modulator; Inflammation; Off-target; p38 MAPK; PNU-120596; α7 nicotinic acetylcholine receptor
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/j.bcp.2020.114297

[Display omitted] PNU-120596 is a classical positive allosteric modulator (PAM) of α7 nicotinic acetylcholine receptor (α7 nAChR) and widely used to investigate the effect of α7 nAChR activation on several inflammation-associated diseases including rheumatoid arthritis, inflammatory bowel disease and cerebral ischemia. In this study, we report that PNU-120596 directly inhibits p38 mitogen-activated protein kinase (MAPK) activity. In 293A cells, p38 MAPK phosphorylation by several factors (oxidative stress, osmotic stress, TNF-α, or muscarinic stimulation) was inhibited by PNU-120596 as well as p38 MAPK inhibitor BIRB-796. Inhibition of p38 MAPK phosphorylation by PNU-120596 was not affected by α7 nAChR antagonist, methyllycaconitine (MLA). In vitro kinase assay revealed that PNU-120596 directly inhibits p38α MAPK-induced activating transcription factor 2 (ATF2) phosphorylation. MKK6-induced phosphorylation of p38α MAPK was also inhibited by PNU-120596. Real-time monitoring of binding to p38α MAPK using fluoroprobe SKF-86002 showed quite rapid binding of PNU-120596 compared to BIRB-796 which is known as a slow binder. Finally, we showed that PNU-120596 suppressed LPS-induced phosphorylation of p38 MAPK and expression of inflammatory factors including TNF-α, IL-6 and COX-2, independent on α7 nAChR activity in microglial cell BV-2. Thus, PNU-120596 might exert an anti-inflammatory effect through not only α7 nAChR potentiation but also direct inhibition of p38 MAPK.