Magnolol suppresses NF-κB activation and NF-κB regulated gene expression through inhibition of IkappaB kinase activation
Autor: | Xiao-Ling Shen, Hon-Yeung Cheung, Guo-Yuan Zhu, Anfernee Kai-Wing Tse, Chi-Keung Wan, Mengsu Yang, Wang-Fun Fong |
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Rok vydání: | 2007 |
Předmět: |
Lipopolysaccharides
Immunology Down-Regulation Apoptosis IκB kinase Biology Lignans chemistry.chemical_compound Cell Line Tumor Humans Luciferase Phosphorylation Molecular Biology U937 cell Tumor Necrosis Factor-alpha Kinase Anti-Inflammatory Agents Non-Steroidal Biphenyl Compounds NF-kappa B Transcription Factor RelA NF-kappa B p50 Subunit NF-κB Molecular biology Magnolol I-kappa B Kinase IκBα Gene Expression Regulation Matrix Metalloproteinase 9 chemistry Cytokines Dimerization |
Zdroj: | Molecular Immunology. 44:2647-2658 |
ISSN: | 0161-5890 |
DOI: | 10.1016/j.molimm.2006.12.004 |
Popis: | The mis-regulation of nuclear factor-kappa B (NF-kappaB) signal pathway is involved in a variety of inflammatory diseases that leds to the production of inflammatory mediators. Our studies using human U937 promonocytes cells suggested that magnolol, a low molecular weight lignan isolated from the medicinal plant Magnolia officinalis, differentially down-regulated the pharmacologically induced expression of NF-kappaB-regulated inflammatory gene products MMP-9, IL-8, MCP-1, MIP-1alpha, TNF-alpha. Pre-treatment of magnolol blocked TNF-alpha-induced NF-kappaB activation in different cell types as evidenced by EMSA. Magnolol did not directly affect the binding of p65/p50 heterodimer to DNA. Immunoblot analysis demonstrated that magnolol inhibited the TNF-alpha-stimulated phosphorylation and degradation of the cytosolic NF-kappaB inhibitor IkappaBalpha and the effects were dose-dependent. Mechanistically, a non-radioactive IkappaB kinases (IKK) assay using immunoprecipitated IKKs protein demonstrated that magnolol inhibited both intrinsic and TNF-alpha-stimulated IKK activity, thus suggesting a critical role of magnolol in abrogating the phosphorylation and degradation of IkappaBalpha. The involvement of IKK was further verified in a HeLa cell NF-kappaB-dependent luciferase reporter system. In this system magnolol suppressed luciferase expression stimulated by TNF-alpha and by the transient transfection and expression of NIK (NF-kappaB-inducing kinase), wild type IKKbeta, constitutively active IKKalpha and IKKbeta, or the p65 subunit. Magnolol was also found to inhibit the nuclear translocation and phosphorylation of p65 subunit of NF-kappaB. In line with the observation that NF-kappaB activation may up-regulate anti-apoptotic genes, it was shown in U937 cells that magnolol enhanced TNF-alpha-induced apoptotic cell death. Our results suggest that magnolol or its derivatives may have potential anti-inflammatory actions through IKK inactivation. |
Databáze: | OpenAIRE |
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