ATP-Binding Pocket-Targeted Suppression of Src and Syk by Luteolin Contributes to Its Anti-Inflammatory Action

• Published in: Mediators of Inflammation 2015-01, Vol.2015 (2015), p.1111-1122-502
• Main Authors: Cho, Jae Youl, Kim, Mi-Yeon, Jeong, Deok, Lee, Jeong-Oog
• Format: Article
• Language: English
• Subjects: Adenosine triphosphatase; Animals; Anti-Inflammatory Agents - pharmacology; Bioflavonoids; Cell Line; Cell Survival - drug effects; Cyclooxygenase 2 - metabolism; Enzymes; Flavones; Flavonoids; Gangrene; Gene expression; Health aspects; Herbal medicine; Humans; Inflammation; Intracellular Signaling Peptides and Proteins - metabolism; Kinases; Luteolin - pharmacology; Medical research; Mice; Nitric oxide; Nitric Oxide - metabolism; Observations; Phosphorylation; Prevention; Protein binding; Protein-Tyrosine Kinases - metabolism; Proteins; src-Family Kinases - metabolism; Studies; Syk Kinase; Tumor necrosis factor-TNF
• ISSN: 0962-9351; 1466-1861
• DOI: 10.1155/2015/967053

Luteolin is a flavonoid identified as a major anti-inflammatory component of Artemisia asiatica. Numerous reports have demonstrated the ability of luteolin to suppress inflammation in a variety of inflammatory conditions. However, its exact anti-inflammatory mechanism has not been fully elucidated. In the present study, the anti-inflammatory mode of action in activated macrophages of luteolin from Artemisia asiatica was examined by employing immunoblotting analysis, a luciferase reporter gene assay, enzyme assays, and an overexpression strategy. Luteolin dose-dependently inhibited the secretion of nitric oxide (NO) and prostaglandin E2 (PGE2) and diminished the levels of mRNA transcripts of inducible NO synthase (iNOS), tumor necrosis factor- (TNF-) α, and cyclooxygenase-2 (COX-2) in lipopolysaccharide- (LPS-) and pam3CSK-treated macrophage-like RAW264.7 cells without displaying cytotoxicity. Luteolin displayed potent NO-inhibitory activity and also suppressed the nuclear translocation of NF-κB (p65 and p50) via blockade of Src and Syk, but not other mitogen-activated kinases. Overexpression of wild type Src and point mutants thereof, and molecular modelling studies, suggest that the ATP-binding pocket may be the luteolin-binding site in Src. These results strongly suggest that luteolin may exert its anti-inflammatory action by suppressing the NF-κB signaling cascade via blockade of ATP binding in Src and Syk.