Magnolol suppresses NF-κB activation and NF-κB regulated gene expression through inhibition of IkappaB kinase activation
Introduction
The bark of Magnolia officinalis (Cortex Magnoliae Officinalis) is widely used as a folk remedy for gastrointestinal disorders, cough, anxiety and allergic diseases. Magnolol, a low molecular weight lignan originally isolated from the Chinese medicinal plant (Wang et al., 2004), shows a number of diverse pharmacological effects including inducing apoptosis (Lin et al., 2001, Ikeda and Nagase, 2002, Yang et al., 2003, Zhong et al., 2003), differentiation (Fong et al., 2005), calcium mobilization (Teng et al., 1990, Wang and Chen, 1998, Zhai et al., 2003), and anti-platelet aggregation (Teng et al., 1988, Pyo et al., 2002). It has also been suggested to have anxiolytic (Maruyama et al., 1998), anti-oxidative (Lo et al., 1994, Shen et al., 1998), anti-fungal and anti-bacterial (Chang et al., 1998, Bang et al., 2000, Ho et al., 2001, Park et al., 2004), anti-viral and anti-carcinogenic (Konoshima et al., 1991) and anti-metastatic activities (Nagase et al., 2001, Ikeda et al., 2003).
Magnolol has a board spectrum anti-inflammatory effect. It suppresses the expression of the inducible nitric oxide synthase (iNOS) in macrophages (Son et al., 2000, Matsuda et al., 2001), the production of inflammatory cytokines interleukin-8 and tumor necrosis factor α (TNF-α) in THP-1 cells (Park et al., 2004, Lee et al., 2005), the formation of prostaglandin E2 (Wang et al., 1995, Lee et al., 2000), and the artherosclerosis mediators monocyte chemotactic protein-1 (MCP-1) and vascular cell adhesion molecule-1 (VCAM-1) (Chen et al., 2001, Chen et al., 2002, Chen et al., 2006). Moreover, magnolol was also reported as a cyclooxygenase (COX) inhibitor (Hsu et al., 2004, Lee et al., 2005).
Nuclear factor-κB (NF-κB) is an ubiquitous nuclear transcription factor regulating dozens of genes involved in inflammation, and also in growth regulation, apoptosis, cancer invasion/metastasis, tumor promotion, carcinogenesis (reviewed in Aggarwal, 2004). NF-κB consists of a family of transcription factors including p65 (RelA), p105/p50, p100/p52, RelB and c-Rel. The classic form of NF-κB is the p65/p50 heterodimer that contains the transcriptional activation domain and is sequestered in the cytoplasm as an inactive complex by IκB (Baldwin, 1996). Acute stimuli such as TNF-α, LPS or PMA led to the activation of IκB kinases (IKK) which in turn phosphorylate Ser32 and Ser36 within the N-terminal response domain of IκB (Karin and Ben-Neriah, 2000). Phosphorylated IκB would undergo ubiquitination-dependent proteolysis and the release of IκB unmasks the nuclear localization signal and results in the translocation of NF-κB to the nucleus, followed by the activation of specific target genes (Karin and Ben-Neriah, 2000).
We investigated whether the attenuation of NF-κB activity may account for the anti-inflammatory and pharmacological effects of magnolol. In a previous study magnolol was shown to reduce the nuclear NF-κB content in TNF-α-stimulated endothelial cells (Chen et al., 2002). However, the action mechanisms are poorly understood. We first established the effects of magnolol on NF-κB-regulated gene expression induced by a number of inflammatory agents and carcinogens. Then, we demonstrated that magnolol inhibited TNF-α stimulated activation of NF-κB in different cells. We further showed that magnolol suppressed IKK activity, stabilized cytoplasmic IκBα and subsequently reduced the nuclear translocation and phosphorylation of the p65 subunit of NF-κB. Magnolol also inhibited NF-κB-dependent reporter gene expression induced by TNF-α, over-expression of NIK, IKK and p65 subunit and enhanced TNF-α-mediated apoptosis.
Section snippets
Materials
Magnolol (Fig. 1A) was obtained from Wako Pure Chemical Industries Ltd., Japan, dissolved in DMSO to make a 100 mM stock solution and stored at −20 °C. LPS (E. coli 0127:B8) and PMA were obtained from Sigma (St. Louis, MO, USA). TNF-α was from Wako Pure Chemical Industries Ltd., Japan, dissolved in 0.1% (w/v) BSA and stored at −80 oC. [γ-32P] ATP was from Perkin-Elmer Life Sciences (Hong Kong) Ltd. Phospho-p65 (Ser536) and phosphor-IκBα (Ser32) antibodies were from Cell Signaling Technology. NF-κB
Magnolol suppressed NF-κB-regulated gene expression stimulated by TNF-α, LPS and PMA
Activation of NF-κB by various stimuli, such as TNF-α, LPS or PMA, induces the expression of diverse groups of target genes that control inflammation and the immune system (Shishodia and Aggarwal, 2004). We induced NF-κB-regulated gene expression by various stimuli and examined the effects of magnolol by RT-PCR. Under different situations treatment of cells with magnolol suppressed either the intrinsic or induced expression of NF-κB-regulated gene products (Fig. 1B).
Magnolol inhibited TNF-α-stimulated NF-κB activation in different cell types
To study the effects of
Discussion
In this paper we have established that magnolol may exert some of its anti-inflammatory and pharmacological effects by affecting the activity of NF-κB. In U937 promonocytes cells magnolol suppresses chemically induced, NF-κB-regulated inflammatory gene products and the suppression is mediated by interfering the binding of NF-κB p65/50 heterdimer to DNA. Mechanistically, magnolol abrogates the IKK activation, results in blockage of IκBα phosphorylation/degradation and p65 subunit translocation.
Acknowledgement
We thank Dr. Ronald T Hay for the NF-κB-dependent luciferase reporter and its control plasmids, Dr. Warner C. Greene for the p65 and IκBα plasmids, Dr. Richard B. Gaynor for the IKKα/β plasmids, and Dr. M. Kracht for the NIK plasmids. This project is supported by special grants from CityU.
References (78)
Nuclear factor-kappaB: the enemy within
Cancer Cell
(2004)- et al.
Tumor necrosis factor and lymphotoxin. Qualitative and quantitative differences in the mediation of early and late cellular response
J. Biol. Chem.
(1994) - et al.
Assay for redox-sensitive transcription factor
Meth. Enzymol.
(2000) - et al.
A JNK-dependent pathway is required for TNFalpha-induced apoptosis
Cell
(2003) - et al.
Magnolol and honokiol enhance HL-60 human leukemia cell differentiation induced by 1, 25-dihydroxyvitamin D3 and retinoic acid
Int. J. Biochem. Cell Biol.
(2005) - et al.
IKKbeta links inflammation and tumorigenesis in a mouse model of colitis-associated cancer
Cell
(2004) - et al.
Cell type-specific expression of the IkappaB kinases determines the significance of phosphatidylinositol 3-kinase/Akt signaling to NF-kappa B activation
J. Biol. Chem.
(2004) - et al.
Modulation of two forms of tumor necrosis factor receptors and their cellular response by soluble receptors and their monoclonal antibodies
J. Biol. Chem.
(1992) - et al.
Tumor necrosis factors-alpha and -beta bind to the same two types of tumor necrosis factor receptors and maximally activate the transcription factor NF-kappa B at low receptor occupancy and within minutes after receptor binding
J. Biol. Chem.
(1990) - et al.
TRADD-TRAF2 and TRADD-FADD interactions define two distinct TNF receptor 1 signal transduction pathways
Cell
(1996)
Mechanisms of the influence of magnolol on eicosanoid metabolism in neutrophils
Biochem. Pharmacol.
Calmodulin-dependent kinase II mediates T cell receptor/CD3- and phorbol ester-induced activation of IkappaB kinase
J. Biol. Chem.
Reactive oxygen species promote TNFalpha-induced death and sustained JNK activation by inhibiting MAP kinase phosphatases
Cell
Kaurane diterpene, kamebakaurin, inhibits NF-kappa B by directly targeting the DNA-binding activity of p50 and blocks the expression of antiapoptotic NF-kappa B target genes
J. Biol. Chem.
One nucleotide in a kappaB site can determine cofactor specificity for NF-kappaB dimers
Cell
Inhibition of p38 mitogen-activated protein kinase reduces TNF-induced activation of NF-kappaB, elicits caspase activity, and enhances cytotoxicity
Exp. Cell Res.
The end of the (cell) line: methods for the study of apoptosis in vitro
Meth. Cell Biol.
Macrophage inflammatory protein-1
Cytokine Growth Factor Rev.
Interleukin-8 (IL-8) and monocyte chemotactic and activating factor (MCAF/MCP-1), chemokines essentially involved in inflammatory and immune reactions
Cytokine Growth Factor Rev.
The ubiquitin-proteasome pathway is required for processing the NF-kappa B1 precursor protein and the activation of NF-kappa B
Cell
Iron-mediated H2O2 production as a mechanism for cell type-specific inhibition of tumor necrosis factor alpha-induced but not interleukin-1beta-induced IkappaB kinase complex/nuclear factor-kappaB activation
J. Biol. Chem.
In vitro antibacterial and anti-inflammatory effects of honokiol and magnolol against Propionibacterium sp
Eur. J. Pharmacol.
Magnolol inhibits Mac-1 (CD11b/CD18)-dependent neutrophil adhesion: relationship with its antioxidant effect
Eur. J. Pharmacol.
Nuclear factor-kappaB: a friend or a foe in cancer?
Biochem. Pharmacol.
Two antiplatelet agents from Magnolia officinalis
Thromb. Res.
EDRF-release and Ca+(+)-channel blockade by magnolol, an antiplatelet agent isolated from Chinese herb Magnolia officinalis, in rat thoracic aorta
Life Sci.
Regulation of the transcriptional activity of the nuclear factor-kappaB p65 subunit
Biochem. Pharmacol.
Magnolol induces cytosolic-free Ca2+ elevation in rat neutrophils primarily via inositol trisphosphate signalling pathway
Eur. J. Pharmacol.
Isolation and purification of honokiol and magnolol from cortex Magnoliae officinalis by high-speed counter-current chromatography
J. Chromatogr. A
The IkappaB kinase complex (IKK) contains two kinase subunits, IKKalpha and IKKbeta, necessary for IkappaB phosphorylation and NF-kappaB activation
Cell
Honokiol and magnolol induce Ca2+ mobilization in rat cortical neurons and human neuroblastoma SH-SY5Y cells
Eur. J. Pharmacol.
The NF-kappa B and I kappa B proteins: new discoveries and insights
Annu. Rev. Immunol.
Antifungal activity of magnolol and honokiol
Arch. Pharm. Res.
An essential role for NF-kappaB in preventing TNF-alpha-induced cell death
Science
Transcriptional regulation of the human MIP-1alpha promoter by RUNX1 and MOZ
Nucl. Acids Res.
Antimicrobial activity of magnolol and honokiol against periodontopathic microorganisms
Planta Med.
Herbal remedy magnolol suppresses IL-6-induced STAT3 activation and gene expression in endothelial cells
Br. J. Pharmacol.
Magnolol attenuates VCAM-1 expression in vitro in TNF-alpha-treated human aortic endothelial cells and in vivo in the aorta of cholesterol-fed rabbits
Br. J. Pharmacol.
Magnolol, a potent antioxidant from Magnolia officinalis, attenuates intimal thickening and MCP-1 expression after balloon injury of the aorta in cholesterol-fed rabbits
Basic Res. Cardiol.
Cited by (60)
The natural compounds, Magnolol or Honokiol, promote adipose tissue browning and resist obesity through modulating PPARα/γ activity
2024, European Journal of PharmacologyMagnolol and Temozolomide exhibit a synergistic anti-glioma activity through MGMT inhibition
2023, Biochimica et Biophysica Acta - Molecular Basis of DiseaseEffects of dietary supplemented with a combination of magnolol, palmatine and β-glucan on growth rate, antioxidant activity, immune response and resistance to Aeromonas hydrophila in tilapia (Oreochromis niloticus)
2022, Aquaculture ReportsCitation Excerpt :Therefore, research had been carried out on herbal and other non-antibiotic feed additives to replace antibiotics has been conducted to improve the health of tilapia (Guo et al., 2019; Deng et al., 2020; Yilmaz et al., 2020, 2022). Magnolol is a low molecular weight lignan extracted from the bark of Magnolia officinalis, and is one of the main active ingredients of Magnoliae Officmalis Cortex (Tse et al., 2007). Currently, there have been many studies on the pharmacology of magnolol, and it has been found to have a wide range of antioxidant (Amorati et al., 2015), anti-inflammatory (Fried and Arbiser, 2009) and antibacterial effects (Ding et al., 2019).
Upregulation of HIF1-α via an NF-κB/COX2 pathway confers proliferative dominance of HER2-negative ductal carcinoma in situ cells in response to inflammatory stimuli
2020, Neoplasia (United States)Citation Excerpt :This was seen only in HER2-negative cells (Fig. 4C). Pre-treatment of HB2 and MCF10A cells with magnolol, PDTC (NF-κB inhibitors [49,50]) or celecoxib (COX2 inhibitor [51]) abolished IL-1β- and TNF-α-induced upregulation of COX2 and HIF1-α, respectively (Fig. 4D, Fig. S4C and Fig. S6), thus confirming the role of both NF-κB and COX2 in mediation of the process. HER2-dependenent specificity of NF-κB activation was additionally confirmed in experiment in which NF-κB p65 translocation to the nucleus upon IL-1β or TNF-α treatment was observed mostly in HER2-negative DCIS cells (Fig. 5A-B and Fig. S7A-B).
Dietary polyphenols and their roles in fat browning
2019, Journal of Nutritional BiochemistryCitation Excerpt :Magnolol is a bioactive polyphenolic component extract of magnolia bark (Magnolia officinalis) that is commonly found in Asian countries. Magnolol is used as a complementary medicine for the treatment of disorders associated with bowel movement, as well as for cough, pain, anxiety and cardiovascular diseases [135–137]. Magnolol has been shown to have anti-inflammatory effects against diabetes and to reduce lipid accumulation in obese animals [138,139].