[Show abstract][Hide abstract] ABSTRACT: The hydroxylated benzene metabolite hydroquinone (HQ) is mainly generated from benzene, an important industrial chemical, and is also a common dietary component. Although numerous reports have addressed the tumorigenesis-inducing effects of HQ, few papers have explored its molecular regulatory mechanism in immunological responses. In this study we characterized Akt (protein kinase B)-targeted regulation by HQ and its derivatives, in suppressing inflammatory responses using cellular, molecular, biochemical, and immunopharmacological approaches. HQ down-regulated inflammatory responses such as NO production, surface levels of pattern recognition receptors, and cytokine gene expression with IC(50) values that ranged from 5 to 10 microm. HQ inhibition was mediated by blocking NF-kappaB activation via suppression of its translocation pathway, which is composed of Akt, I kappaB alpha kinase beta, and I kappaB alpha. Of the targets in this pathway, HQ directly targeted and bound to the sulfhydryl group of Cys-310 of Akt and sequentially interrupted the phosphorylation of both Thr-308 and Ser-473 by mediation of beta-mercaptoethanol, according to the liquid chromatography/mass spectroscopy analysis of the interaction of HQ with an Akt-derived peptide. Therefore, our data suggest that Akt and its target site Cys-310 can be considered as a prime molecular target of HQ-mediated immunosuppression and for novel anti-Akt-targeted immunosuppressive drugs.
Journal of Biological Chemistry 03/2010; 285(13):9932-48. · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Acer tegmentosum has been traditionally used for folk medicine to treat hepatic disorders such as hepatitis, hepatic cancer, and hepatic cirrhosis. In this study, we demonstrate the ethno-pharmacological activity of Acer tegmentosum in in vitro and in vivo inflammatory conditions.
The 70% ethanol extract (At-EE) of Acer tegmentosum dose-dependently diminished the production of nitric oxide (NO), tumour necrosis factor (TNF)-alpha, and prostaglandin (PG)E(2), in lipopolysaccharide (LPS)-activated RAW264.7 cells and peritoneal macrophages, by a transcriptional mechanism. At-EE also suppressed the activation of nuclear factor (NF)-kappaB, activator protein (AP)-1, and cAMP-responsive element binding (CREB), and simultaneously blocked their upstream inflammatory signalling cascades, including Akt, p38, and JNK. Furthermore, At-EE protected against LPS-induced cell death induced by reactive oxygen species (ROS) and reactive nitrogen species (RNS) and neutralized reactive species generation. In agreement with the in vitro results, orally administered At-EE strongly ameliorated ear oedema formation induced by arachidonic acid.
At-EE displays strong anti-inflammatory activities in vitro and in vivo, contributing to its major ethno-pharmacological role such as anti-hepatitis remedy and may be applicable to novel anti-inflammatory therapeutics.
Journal of ethnopharmacology 03/2010; 128(1):139-47. · 2.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Regulator of G protein signaling (RGS) family members, such as RGS2, interact with Galpha subunits of heterotrimeric G proteins, accelerating the rate of GTP hydrolysis and attenuating the intracellular signaling triggered by the G protein-coupled receptor-ligand interaction. They are also reported to regulate G protein-effector interactions and form multiprotein signaling complexes. Ischemic stress-induced changes in RGS2 expression have been described in astrocytes, and these changes are associated with intracellular signaling cascades, suggesting that RGS2 upregulation may be an important mechanism by which astrocytes may regulate RGS2 function in response to physiological stress. However, information on the functional roles of stress-induced modulation of RGS2 protein expression in astrocyte function is limited. We report the role of ischemic stress in RGS2 protein expression in rat C6 astrocytoma cells and primary mouse astrocytes. A marked increase in RGS2 occurred after ischemic stress induced by chemicals (sodium azide and 2-deoxyglucose) or oxygen-glucose deprivation (OGD, real ischemia). RGS2 mRNA expression was markedly enhanced by 1 h of exposure to chemical ischemia or 6 h of OGD followed by 2 or 6 h of recovery, respectively. This enhanced expression in primary astrocytes and C6 cells was restored to baseline levels after 12 h of recovery from chemically induced ischemic stress or 4-6 h of recovery from OGD. RGS2 protein was also significantly expressed at 12-24 h of recovery from ischemic insult. Ischemia-induced RGS2 upregulation was associated with enhanced apoptosis. It significantly increased annexin V-positive cells, cleaved caspase-3, and enhanced DNA ladder formation and cell cycle arrest. However, a small interfering RNA (siRNA)-mediated RGS2 knockdown reversed the apoptotic cell death associated with ischemia-induced RGS2 upregulation. Upregulated RGS2 was significantly inhibited by SB-203580, a p38 MAPK inhibitor. Rottlerin, a potent inhibitor of PKCdelta, completely abrogated the increased RGS2 expression. We also examine whether ischemia-induced RGS2-mediated apoptosis is affected by siRNA-targeted endogenous PKCdelta downregulation or its phosphorylation. Although RGS2 upregulation was not affected, siRNA transfection significantly suppressed endogenous PKCdelta mRNA and protein expressions. Ischemia-induced PKCdelta phosphorylation and caspase-3 cleavage were dose dependently inhibited by PKCdelta knockdown, and this endogenous PKCdelta suppression reversed ischemia-induced annexin V-positive cells. This study suggests that ischemic stress increases RGS2 expression and that this condition contributes to enhanced apoptosis in C6 cells and primary astrocytes. The signaling it follows may involve PKCdelta and p38 MAPK pathways.
[Show abstract][Hide abstract] ABSTRACT: Ginsenoside Rg3, a single ginseng saponin, is known to be a major anti-platelet component of protopanaxadiol that is isolated from Korean red ginseng. In this study, we investigated whether dihydroginsenoside Rg3, a stable chemical derivative of ginsenoside Rg3, also demonstrated anti-platelet activity. Dihydroginsenoside Rg3 inhibited thrombin-induced platelet aggregation in a concentration-dependent manner with an IC50 (concentration producing 50% inhibition) of 18.8 ± 0.4 μM. Ginsenoside Rg3 inhibited platelet aggregation which was induced by thrombin (0.1 U mL−1) with an IC50 of 40.2 ± 0.9 μM. We next determined whether dihydroginsenoside Rg3 affected different types of ligand-induced platelet aggregation. We found that dihydroginsenoside Rg3 inhibited collagen-induced platelet aggregation with an IC50 of 20.0 ± 0.9 μM. To elucidate the inhibitory mechanism of dihydroginsenoside Rg3 on aggregation, we analysed its downstream signalling pathway. It was interesting to note that dihydroginsenoside Rg3 elevated cyclic AMP production in resting platelets, but did not affect cyclic GMP production. In addition, we found that dihydroginsenoside Rg3 potently suppressed phosphorylation of extracellular signal-regulated kinase 2 (ERK2), which was stimulated by collagen (2.5 μg mL−1), but not of p38 mitogen-activated protein kinase. Taken together, our results indicate that dihydroginsenoside Rg3 potently inhibited platelet aggregation via the modulation of downstream signalling components such as cAMP and ERK2.
Journal of Pharmacy and Pharmacology. 02/2010; 60(11):1531 - 1536.
[Show abstract][Hide abstract] ABSTRACT: Syringin was found to possess immunomodulatory activity by which it inhibited the in-vitro immunohaemolysis of antibody-coated sheep erythrocytes by guinea-pig serum through suppression of C3-convertase of the classical complement. In this study, we examined its in-vitro and in-vivo activity on tumour necrosis factor (TNF)- and nitric oxide (NO) production, CD4 + T cell and CD8+ cytotoxic T cell (CTLL-2) proliferation, and croton oil-, arachidonic acid- and fluorescein-isothiocynate (FITC)-induced mouse ear oedema model. Syringin significantly inhibited both TNF- production from lipopolysaccharide (LPS)-stimulated RAW264.7 cells and CD8+ T cell (CTLL-2) proliferation in a dose-dependent manner, whereas neither NO production nor CD4+ T cell proliferation were blocked even by high concentrations of syringin. In the in-vivo experiments, syringin also significantly suppressed FITC-induced ear oedema in mice but not the ear oedema induced by croton or arachidonic acid. These results suggest that syringin may be implicated as an immunomodulator having an anti-allergic effect rather than an antiinflammatory effect. The anti-allergic effect of syringin seems to be due, in part, to inhibition of TNF- production and cytotoxic T cell proliferation.
Journal of Pharmacy and Pharmacology. 02/2010; 53(9):1287 - 1294.
[Show abstract][Hide abstract] ABSTRACT: Coffee is a popular beverage worldwide with various nutritional benefits. Diterpene cafestol, one of the major components of coffee, contributes to its beneficial effects through various biological activities such as chemopreventive, antitumorigenic, hepatoprotective, antioxidative and antiinflammatory effects. In this study, we examined the precise molecular mechanism of the antiinflammatory activity of cafestol in terms of prostaglandin E(2) (PGE(2)) production, a critical factor involved in inflammatory responses. Cafestol inhibited both PGE(2) production and the mRNA expression of cyclooxygenase (COX)-2 from lipopolysaccharide (LPS)-treated RAW264.7 cells. Interestingly, this compound strongly decreased the translocation of c-Jun into the nucleus and AP-1 mediated luciferase activity. In kinase assays using purified extracellular signal-regulated kinase 2 (ERK2) or immunoprecipitated ERK prepared from LPS-treated cells in the presence or absence of cafestol, it was found that this compound can act as an inhibitor of ERK2 but not of ERK1 and mitogen-activated protein kinase kinase 1 (MEK 1). Therefore our data suggest that cafestol may be a novel ERK inhibitor with AP-1-targeted inhibitory activity against PGE(2) production in LPS-activated RAW264.7 cells.
[Show abstract][Hide abstract] ABSTRACT: It has been reported that red ginseng acidic polysaccharide (RGAP), isolated from Korean red ginseng, displays immunostimulatory and anti-tumor activities. In a follow-up study, we have carried out a study on the anti-hyperlipidemic effects of RGAP using hyperlipidemic rats acutely induced by Triton WR1339 or corn oil intravenously injected. Oral administration of RGAP (100 to 1000 mg/kg) dose-dependently reduced the serum levels of triglyceride (TG) up-regulated by Triton WR1339, an inducer of endogenous model hyperlipidemia. Moreover, RGAP treatment was shown to significantly decrease the levels of non-esterified fatty acid (NEFA) concomitant with TG reduction. However, such reduction effects were not observed in cases of total cholesterol (TC) and phospholipid levels increased under the same conditions, although there was an inhibitory tendency. Similar suppressive patterns were also seen in hepatic parameters (total lipids and TG) under the same conditions. The exogenous hyperlipidemic rat condition triggered by corn oil also supported the anti-hyperlipidemic activity of RGAP in serum and hepatic parameters of TG and NEFA. Interestingly, RGAP significantly enhanced the serum activity of lipoprotein lipase, a key hydrolytic enzyme of lipid molecules in lipoprotein, in a dose-dependent manner up to 80%, implying potential involvement of this enzyme in lowering TG and NEFA by RGAP. Therefore, our data suggest that RGAP may play an additional role in reducing hyperlipidemic conditions, which can be used as a valuable neutraceutical application for the treatment of hyperlipidemia.
[Show abstract][Hide abstract] ABSTRACT: Although its demand increased greatly due to the volatile strong flavor and bioactive molecules, little information has been
about the cultural characteristics of Tricholoma matsutake. In this study, we investigated the optimal medium composition of liquid culture with the goal of shortening the culture
period, and to maximize polysaccharide production and mycelial growth. From these experiments we found that the optimal medium
contained 40 g/L, glucose; 30 g/L, yeast extract; 1.5 g/L, KH2PO4; and 1 g/L MgSO4·7H2O. In flask culture, the maximum mycelial growth and polysaccharide production were 22.45 and 5.3 g/L, which were about 9
and 3 g/L higher than that at the basal medium, respectively.
-exo-polysaccharide-mycelial growth-carbon-to-nitrogen ratio-trace elements
Biotechnology and Bioprocess Engineering 01/2010; 15(2):293-298. · 1.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Diterpene kahweol, one of the major components in coffee, has anti-cancer, anti-oxidative, and anti-inflammatory activity. In this study, we explored the molecular mechanism of the anti-inflammatory activity of kahweol. Lipopolysaccharide (LPS)-activated RAW264.7 cells were used to explore the modulatory role of kahweol on nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production and the activation of signaling proteins and transcription factors using immunoblotting and reverse transcription-polymerase chain reaction (RT-PCR). Kahweol diminished both the production of NO and PGE(2) and the mRNA expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2. Interestingly, this compound suppressed the phospho-signal transducers and activators of transcription (STAT)-1 and p65/nuclear factor (NF)-kappaB levels in the nucleus but not c-Jun and c-fos. In conjunction, the phosphorylation of Akt and Janus kinase (JAK)2 also decreased. Therefore, our data suggest that kahweol in coffee may be an anti-inflammatory modulator with NF-kappaB/STAT-1-targeted inhibitory properties in LPS-activated RAW264.7 cells.
[Show abstract][Hide abstract] ABSTRACT: Cinnamaldehyde (CA) has been known to exhibit anti-inflammatory and anticancer effects. Although numerous pharmacological effects have been demonstrated, regulatory effect of CA on the functional activation of monocytes and macrophages has not been fully elucidated yet. To evaluate its monocyte/macrophage-mediated immune responses, macrophages activated by lipopolysaccharide (LPS), and monocytes treated with proaggregative antibodies, and extracellular matrix protein fibronectin were employed. CA was able to suppress both the production of nitric oxide (NO) and upregulation of surface levels of costimulatory molecules (CD80 and CD69) and pattern recognition receptors (toll-like receptor 2 (TLR2) and complement receptor (CR3)). In addition, CA also blocked cell-cell adhesion induced by the activation of CD29 and CD43 but not cell-fibronectin adhesion. Immunoblotting analysis suggested that CA inhibition was due to the inhibition of phosphoinositide-3-kinase (PI3K) and phosphoinositide-dependent kinase (PDK)1 as well as nuclear factor-(NF-) kappaB activation. In particular, thiol compounds with sulphydryl group, L-cysteine and dithiothreitol (DTT), strongly abrogated CA-mediated NO production and NF-kappaB activation. Therefore, our results suggest that CA can act as a strong regulator of monocyte/macrophage-mediated immune responses by thiolation of target cysteine residues in PI3K or PDK1.
Mediators of Inflammation 01/2010; 2010:529359. · 3.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Platelets, though anucleated, possess several transcription factors, including NF-kappaB, that exert non-genomic functions regulating platelet activation. Since platelets have not only been recognized as central players of homeostasis, but also participated in pathological conditions such as thrombosis, atherosclerosis, and inflammation, we examined rat platelet NF-kappaB expression and evaluated the effects of anti-inflammatory drug BAY 11-7082, an inhibitor of NF-kappaB activation, in platelet physiology. Western blotting revealed that rat platelets express NF-kappaB. BAY 11-7082, dose dependently, inhibited collagen- or thrombin-induced-platelet aggregation. ATP release, TXB(2) formation, P-selectin expression, and intercellular Ca(2+) concentration activated by collagen were reduced in BAY 11-7082-treated platelets. BAY 11-7082 elevated intracellular levels of cAMP, but not cGMP, and its co-incubation with cAMP-activating agent (forskolin) or its hydrolyzing enzyme inhibitor (3-isobutyl-1-methylxanthine, IBMX), synergistically inhibited collagen-induced-platelet aggregation. In addition, vasodilator-stimulated-phosphoprotein (VASP) phosphorylation was enhanced in BAY 11-7082-treated platelets, which was partially inhibited by a protein kinase A (PKA) inhibitor, H-89. Moreover, while p38 mitogen-activated protein kinase (MAPK) was not affected, BAY 11-7082 attenuated c-Jun N-terminal kinase 1 (JNK1) and extracellular-signal-regulated protein kinase 2 (ERK2) phosphorylations. In conclusion, BAY 11-7082 inhibits platelet activation, granule secretion, and aggregation, and that this effect is mediated by inhibition of JNK1 and ERK2 phosphorylations, and partially by stimulation of cAMP-dependent PKA VASP phosphorylation. The ability of BAY 11-7082 to inhibit platelet function might be relevant in cases involving aberrant platelet activation where the drug is considered as anti-atherothrombosis, and anti-inflammatory therapy.
European journal of pharmacology 11/2009; 627(1-3):85-91. · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mushroom-derived polysaccharides (beta-glucans) are considered as a valuable biopharmaceutical principle without displaying side effects. Although Tricholoma matsutake is well-known mushroom in Korea, Japan and China, the immunoregulatory roles of T. matsutake-derived polysaccharides were not fully elucidated yet. In this study, we continued to evaluate the immunomodulatory effect of T. matsutake-derived polysaccharide fraction (TmC-2) using functional activation models of macrophages, monocytes and splenic lymphocytes. TmC-2 treatment strongly increased the production of NO and TNF-alpha. Phagocytic uptake and ROS generation was also up-regulated by TmC-2. Interestingly, TmC-2 stimulated CD29-mediated cell-cell or cell-finbronectin adhesions in monocytes, while CD43-mediated cell adhesion was down-regulated. Interestingly, the enhancement of proliferation and IFN-gamma production was striking observed in TmC-2-treated splenic lymphocytes. The activation seemed to be mediated by up-regulating intracellular signaling cascades such as PI3K/Akt and MAPK (ERK and p38) and by the involvement of surface receptors (dectin-1 and TLR-2). Therefore, our results suggest that this TmC-2 from T. matsutake can be developed as a promising immunostimulatory principle, applicable to people with lowered immunomodulatory potentials.
Archives of Pharmacal Research 11/2009; 32(11):1565-72. · 1.54 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Saponins are valuable principles found in various herbal medicine with pharmaceutical, cosmetical and nutraceutical merits. In this study, we evaluated the protective role of saponin fraction (Cl-SF), prepared from Codonopsis lanceolata, an ethnopharmacologically famous plant in Korea, China and Japan, on water immersion stress-induced liver damage and radical generation. Cl-SF clearly decreased the up-regulated levels of serum glutamate-oxalacetate transaminase and glutamate-pyruvate-transaminase induced by water-immersed stress conditions. Furthermore, Cl-SF seemed to block the stress-induced radicals. Thus, Griess and DPPH assays revealed that Cl-SF significantly suppressed both radical generation in sodium nitroprusside-treated RAW264.7 cells and nitric oxide production in LPS-treated RAW264.7 cells. Therefore, these results suggest that Cl-SF may be considered as a promising stress-regulatory principle with radical scavenging actions.
Archives of Pharmacal Research 10/2009; 32(10):1441-6. · 1.54 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ginsenosides (G) are biologically active saponin compounds found in Panax ginseng. Although these compounds are reported to possess numerous biological activities, recent issues have arisen regarding their immunosuppressive and anti-inflammatory roles in inflammatory cells. This is because 1) inflammation, managed by a large amount of different pro-inflammatory mediators such as cytokines, nitric oxide (NO) and prostaglandin (PG)E 2 , is now considered as a principle cause of most immunological diseases, such as cancer and autoimmunity; and 2) some ginsenosides (e.g., G-Rb1, G-Rd and G-Rh2) can modulate these phenomena effectively by inhibiting the production of inflammatory mediators through suppressing the activation of nuclear factor (NF)-κB and its upstream signaling cascade. This review, therefore, discusses the in vitro and in vivo anti-inflammatory effects of ginsenosides in detail and proposes the possibility that ginsenosides, or their derivatives, can be developed as pharmaceutically useful drugs against NF-κB-mediated inflammatory diseases.
AFRICAN JOURNAL OF BIOTECHNOLOGY 09/2009; 8:3682-3690. · 0.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sorbus commixta has been known as enthopharmacologically valuable plant in Korea, China and Japan. This plant has been reported to display numerous pharmacological activities such as anti-oxidative, anti-ice nucleation, anti-vascular inflammation, anti-lipid peroxidation, anti-atherogenic, and vasorelaxant effects. Although numerous pharmacological potentials have been demonstrated, immunomodulatory effect of this plant has not been fully elucidated yet. To evaluate its anti-inflammatory activity, macrophages activated by lipopolysaccharide (LPS) were employed and the production of inflammatory mediators was explored in terms of understanding its molecular inhibitory mechanism. 70% ethanol extract (Sc-EE) from S. commixta strongly suppressed the production of nitric oxide (NO) and prostaglandin (PG) E 2 but not tumor necrosis factor (TNF)-. The extract also clearly diminished the mRNA levels of inducible NO synthase (iNOS) and cyclo-oxygenase (COX)-2, implying that the inhibition occurs at the transcriptional level. Indeed, Western blot analysis and luciferase activity assay revealed that Sc-EE remarkably suppressed AP-1 translocation and its activity, respectively. In agreement, this extract strongly suppressed the phosphorylation of JNK, a prime enzyme responsible for AP-1 translocation. Therefore, our results suggest that Sc-EE can be applied as an anti-inflammatory herbal medicine. To prove this possibility, in vivo efficacy test will be further continued in the following project.
Journal of Medicinal Plants Research. 09/2009; 3:600-607.
[Show abstract][Hide abstract] ABSTRACT: Salicornia (S.) herbacea L. (Chenopodiaceae) is a salt marsh plant and one of the most salt tolerant species on Western coast of Korea. In a long time, S. herbacea has been prescribed in traditional medicines for the treatment of intestinal ailments, nephropathy, and hepatitis in Oriental countries. In addition, S. herbacea has recently reported to be effective on the atherosclerosis, hyperlipidemia, and diabetes. A variety of pharmacological experiments have revealed that solvent-extracted fractions of S. herbacea exhibited anti-oxidative, anti-microbial, anti-proliferative, and anti-inflammatory activities, supporting rationale behind its several traditional uses. Tungtungmadic acid, quercetin 3-O-glucoside, and isorhamnetin 3-O-glucoside have been isolated from S. herbacea, and identified as active ingredients of biological and pharmacological activities. Due to the easily collection of the plant and remarkable biological activities, this plant has become the food and medicine in seashore area of Korea. This review presents comprehensively analyzed information on the botanical, chemical, and pharmacological aspects of S. herbacea.
Journal of Medicinal Plants Research. 09/2009; 3:548-555.
[Show abstract][Hide abstract] ABSTRACT: Most, if not all, Basidiomycetes mushrooms have biologically active polysaccharides showing potent antitumor activity with immunomodulating properties. These polysaccharides have various chemical compositions and belong primarily to the beta-glucan group. In this study, the crude water-soluble polysaccharide HEF-P, which was obtained from the fruiting body of Hericium erinaceus by hot water extraction and ethanol precipitation, was fractionated by DEAE-cellulose and Sepharose CL-6B column chromatographies. This process resulted in four polysaccharide fractions, named HEF-NP Fr I, HEF-NP Fr II, HEF-AP Fr I, and HEF-AP Fr II. Of these fractions, HEF-AP Fr II was able to upregulate the functional events mediated by activated macrophages, such as production of nitric oxide and expression of cytokines (IL-1beta and TNF-beta). The molecular mass of HEF-AP Fr II was estimated by gel filtration to be 13 kDa. Its structural characteristics were investigated by a combination of chemical and instrumental analyses, including methylation, reductive cleavage, acetylation, Fourier transform infrared spectroscopy (FT-IR), and gas chromatography-mass spectrometry (GC-MS). Results indicate that HEF-AP Fr II is a low-molecular-mass polysaccharide with a laminarin-like triple helix conformation of a beta-1,3-branched-beta-1,6-glucan.
Journal of Microbiology and Biotechnology 09/2009; 19(9):951-9. · 1.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The regulatory effects of honokiol on the cellular responses of macrophages and monocytes were evaluated. Specifically, we investigated the effects of honokiol with respect to lipopolysaccharide (LPS)-induced cytotoxicity, LPS- or phorbol-12-myristate-13-acetate (PMA)-mediated morphological changes, and relevant events (FITC-dextran-induced phagocytic uptake). Honokiol blocked the LPS-induced cytotoxicity of RAW264.7 cells in a dose-dependent manner. In addition, honokiol appeared to block the production of cytotoxic cytokines such as interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha, nitric oxide (NO), and reactive oxygen species (ROS). Moreover, honokiol strongly prevented the morphological changes in RAW 264.7 and U937 cells that were induced by LPS and PMA. The surface levels of marker proteins, which are up-regulated under the morphological changes of RAW264.7 and U937 cells, were also diminished. The data presented here strongly suggest that the honokiol modulates various cellular responses managed by macrophages and monocytes. [BMB reports 2009; 42(9): 574-579].
[Show abstract][Hide abstract] ABSTRACT: Although the role of the actin cytoskeleton has become increasingly elucidated, the role of actin polymerization in inflammatory processes remains poorly understood. Here, we examine the role of the actin cytoskeleton during LPS-mediated inflammatory events in RAW264.7 cells and peritoneal macrophages. We observed that actin cytoskeleton disruption by cytochalasin B and siRNA to cytoplasmic actin strongly down-regulated LPS-mediated inflammatory responses such as NO production, PGE(2) release, and TNF-alpha secretion. Actin cytoskeleton disruption by cytochalasin B down-regulated a series of signaling cascades including PI3K, Akt, and IKK, but not MAPKs, necessary for NF-kappaB activation without down-regulating total forms of the proteins as assessed by measuring their phosphorylation levels. In particular, cytochalasin B significantly inhibited LPS-induced both phosphorylation and kinase activity of Src without altering total level, implying that Src may be a potential pharmacological target of actin cytoskeleton rearrangement. Moreover, the direct association of Src with actin was actin polymerization-dependent according to immunoprecipitation analysis performed with a GFP-actin wild type and HA-tagged Src. Therefore, our data suggest that actin cytoskeleton rearrangement may be a key event during the regulation of inflammatory responses that modulates the activity of Src and its downstream signaling molecules.
[Show abstract][Hide abstract] ABSTRACT: Ceramides are signaling molecules that regulate differentiation, proliferation, and apoptosis of cells. In this study, we report novel modulatory effects of ceramides on the functional activation of beta1 integrins (CD29) and their associated molecules, such as CD98 and CD147, using U937 cell-cell or cell-fibronectin (FN) adhesion events. Cell-permeable ceramides (C2- or C6-ceramides) effectively blocked monocytic cell-cell adhesion, mediated by CD29, CD98, and CD147, and cell-FN adhesion in a dose-dependent manner. The suppressive effect was demonstrated with the treatment of only ceramides but not other sphingolipid metabolites or analogs, such as sphingosine, dihydrosphingosine, and fumonisin B1. Ceramides displayed a distinct inhibitory profile on cell-cell and cell-FN adhesions compared with other inhibitors such as PD98059 (an extracellular signal-related kinase (ERK) inhibitor), SB203580 (a p38 inhibitor), rottlerin (a PKCdelta inhibitor), and cytochalasin B (an actin cytoskeleton disruptor). Interestingly, C6-ceramide inhibited the phosphorylation of CD29 induced by MEM101A treatment and down-regulated surface levels of CD29, CD98, and CD147, as well as CD49d. Since there are no reports showing that ceramides act as negative regulators of the functional activation of CD29, our results therefore suggest a novel possibility that ceramides can be used as a therapeutic drug regarding CD29-mediated pathological events, including tumor metastasis, inflammatory states, granuloma formation, and blood vessel occlusion.