Biomedical subjects

Eunkyung Lee

Publications and source records attributed to Eunkyung Lee.

At least 19 recordsLinked to original sources

PubMed2006

Deoxypodophyllotoxin (DPT) inhibits eosinophil recruitment into the airway and Th2 cytokine expression in an OVA-induced lung inflammation.

The effect of deoxypodophyllotoxin (DPT) isolated from Anthriscus sylvestris Hoffm. was evaluated in an IN VIVO animal model for antiasthmatic activity. DPT (1.0 to 5 mg/kg) was given orally to ovalbumin (OVA)/alum-induced asthmatic mice. DPT reduced the number of infiltrated eosinophils in bronchoalveolar lavage (BAL) fluid in a dose-dependent manner. Dexamethasone (5 mg/kg), which was used as a positive control, also strongly inhibited the number of infiltrated eosinophils. The effect of DPT on a transcript profile in a murine asthma model was determined by RT-PCR, which showed that DPT decreased the mRNA levels of the Th2 cytokines. Northern blot analysis showed that DPT also reduced both the eotaxin and arginase I mRNA levels in a dose-dependent manner.

Animals↗

PubMed2006

Effects of methyl gallate on arachidonic acid metabolizing enzymes: Cyclooxygenase-2 and 5-lipoxygenase in mouse bone marrow-derived mast cells.

Methyl gallate (MG) is a medicinal herbal product that is isolated from Paeonia lactiflora that inhibits cyclooxygenase-2 (COX-2) dependent phases of prostaglandin D2 (PGD2) generation in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with an IC50 values of 17.0 microM. This compound also found inhibited the COX-2-dependent conversion of the exogenous arachidonic acid to PGD2 in a dose-dependent manner with an IC50 values of 19.0 microM, using a COX enzyme assay kit. However, at concentrations up to 80 microM, MG did not inhibit COX-2 protein expression in BMMC, indicating that MG inhibits COX-2 activity directly. Furthermore, MG consistently inhibited the production of leukotriene C4 (LTC4) in a dose dependent manner, with an IC50 value of 5.3 microM. These results demonstrate that MG has a dual cyclooxygenase-2/5-lipoxygenase inhibitory activity, which might provide the basis for novel anti-inflammatory drugs.

Animals↗

PubMed2006

Anti-asthmatic activity of an ethanol extract from Saururus chinensis.

As an attempt to find bioactive medicinal herbs exerting anti-asthmatic activity, the effects of an ethanol extract from the parts of Saururus chinensis were evaluated in both in vitro and in vivo. The ethanol extract of S. chinensis (ESC) inhibited generation of the cyclooxygenase-2 (COX-2) dependent phases of prostaglandin D(2) in bone marrow-derived mast cells in a concentration-dependent manner with an IC(50) value of 14.3 microg/ml. ESC also inhibited leukotriene C(4) production with an IC(50) value of 0.3 microg/ml. This demonstrates that ESC has COX-2/5-lipoxygenase dual inhibitory activity. In addition, this compound inhibited degranulation reaction in a dose dependent manner, with an IC(50) value of 1.3 microg/ml. An ovalbumin induced mouse asthmatic animal model was used to determine its in vivo anti-asthmatic activity. The oral administration (50-200 mg/kg) of ESC reduced the number of infiltrated eosinophil in a bronchoalveolar lavage fluid. Furthermore, ESC (100 mg/kg) inhibited the eotaxin and IL-4 mRNA expression levels. These results suggest that the anti-asthmatic activity of S. chinensis might in part occur via the inhibition of eicosanoid generation, degranulation as well as the down regulation of IL-4 and eotaxin mRNA expression.

Animals↗

PubMed2006

Anti-inflammatory activity of Ailanthus altissima in ovalbumin-induced lung inflammation.

As part of an ongoing investigation to find bioactive medicinal herbs exerting anti-inflammation activity, the effect of an ethanol extract from the parts of Ailanthus altissima (Simaroubaceae) was evaluated in both in vitro and in in vivo system. The ethanol extract of A. altissima (EAa) inhibited generation of the cyclooxygenase-2 (COX-2) dependent phases of prostaglandin D2 in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with an IC50 value of 214.6 microg/ml. However, this compound did not inhibit COX-2 protein expression up to a concentration of 400 microg/ml in the BMMC, indicating that EAa directly inhibits COX-2 activity. In addition, EAa inhibited leukotriene C4 production with an IC50 value of 25.7 microg/ml. Furthermore, this compound inhibited degranulation reaction in a dose dependent manner, with an IC50 value of 27.3 microg/ml. Ovalbumin (OVA)-sensitized mice were orally pretreated with EAa before aerosol challenges. EAa reduced the eosinophil infiltration into the airway and the eotaxin, IL-4, and IL-13 mRNA expression levels. These results suggest that the anti-inflammation activity of A. altissima in OVA-induced lung inflammation may occur in part via the down regulation of T(H)2 cytokines and eotaxin transcripts as well as the inhibition of inflammatory mediators.

Ailanthus↗

PubMed2005

Identification of inducible genes during mast cell differentiation.

Mast cells play an important role in allergic inflammation by releasing their bioactive mediators. The function of mast cells is enhanced by stimulation because of the induction of specific genes and their products. While many inducible genes have been elucidated, we speculated that a significant number of genes remain to be identified. Thus, we applied differential display (dd) PCR to establish a profile of the induced genes in bone marrow-derived mast cells (BMMCs) after they were co-cultured with 3T3 fibroblasts. To date, 150 cDNA fragments from the connective-type mast cells (CTMCs) were amplified. Among them, thirty cDNA fragments were reamplified for cloning and sequencing. The ddPCR strategy revealed that serine proteases were the most abundant genes among the sequenced clones induced during the maturation. Additionally, unknown genes from the co-culture of BMMCs with 3T3 fibroblasts were identified. We confirmed their induction in the CTMCs by Northern blot analysis and RT-PCR. Characterization of these induced genes during the maturation processes will provide insight into the functions of mast cells.

3T3 Cells↗

PubMed2005

Induction of Ym1/2 in mouse bone marrow-derived mast cells by IL-4 and identification of Ym1/2 in connective tissue type-like mast cells derived from bone marrow cells cultured with IL-4 and stem cell factor.

Mast cells play an important role in allergic inflammation by releasing various bioactive mediators. The function of mast cells is enhanced by various stimuli, partly due to the induction of specific genes and their products. Although many inducible genes have been identified, a significant number of genes remain to be identified. Therefore, this study used PCR-selected cDNA subtraction to establish the profile of induced genes in the connective tissue (CT) type-like mast cells derived from bone marrow cells cultured in the presence of IL-4 and stem cell factor. Two hundred and fifty cDNA clones were obtained from the CT type-like mast cells by PCR-selected cDNA subtraction. Among them, Ym1/2, a chitinase-like protein, is one of the most abundantly induced genes. Ym1 is produced by activated macrophages in a parasitic infection, whereas its isotype, Ym2, is highly upregulated in allergic lung disease. In order to differentiate which isotype is expressed in bone marrow cells, specific primers for bone marrow-derived mast cells (BMMC), and CT type-like mast cells were used for RT-PCR. The results showed that Ym1 was constitutively expressed in bone marrow cells and gradually decreased in the presence of IL-3, whereas Ym2 was induced only in the presence of IL-4. CT type-like mast cells from bone marrow cells expressed Ym1 throughout the culture period and Ym2 was induced only by the addition of IL-4 into BMMC, indicating that IL-4 is essential for the expression of Ym1/2 genes.

Animals↗

PubMed2005

Ginkgetin, a Biflavone from Ginko biloba leaves, inhibits cyclooxygenases-2 and 5-lipoxygenase in mouse bone marrow-derived mast cells.

Ginkgetin, a biflavone from Ginkgo biloba leaves, was previously reported to be a phospholipase A(2) inhibitor and this compound showed the potent antiarthritic activity in rat adjuvant-induced arthritis as well as analgesic activity. This investigation was carried out to find effects on cyclooxygenase-2 (COX-2) in vitro effect. Ginkgetin inhibits COX-2 dependent phases of prostaglandin D(2) (PGD(2)) generation in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with IC(50) values of 0.75 microM. Western blotting probed with specific anti-COX-2 antibodies showed that the decrease in quantity of the PGD(2) product was accompanied by a decrease in the COX-2 protein level. In addition, this compound consistently inhibited the production of leukotriene C(4) (LTC(4)) in a dose dependent manner, with an IC(50) value of 0.33 microM. These results demonstrate that ginkgetin has a dual cyclooxygenase-2/5-lipoxygenase inhibitory activity. Furthermore, this compound also inhibited degranulation reaction in a dose dependent manner, with an IC(50) value of 6.52 microM. Therefore, this compound might provide a basis for novel anti-inflammatory agents.

Animals↗

PubMed2005

cDNA cloning and expression of biologically active platelet activating factor-acetylhydrolase (PAF-AH) from bovine mammary gland.

Platelet activating factor (PAF)-acetylhydrolase (PAF-AH) is an enzyme that hydrolyzes the acetyl ester at the sn-2 position of PAF, and converts it to the inactive metabolite, lyso PAF. This enzyme is distributed widely in the intracellular as well as the extracellular matrix and is believed to be a defense mechanism that protects the host against the toxic effects of PAF and other biologically active oxidized phospholipids. Purification and expression of cDNA cloning of the intracellular and extracellular types of PAF-AH from several sources from different species have been reported. In this study, the cDNA for PAF-AH was cloned by reverse transcription (RT)-PCR from total RNA of bovine mammary gland. The complete amino acid sequences from the cDNA contains 444 amino acids and was identical to that of the PAF-AH isolated from the bovine spleen cDNA library except for two mismatches of amino acid residues (Thr-247 to Met and Ile-431 to Thr). Recombinant PAF-AH was expressed in HEK 293 cells, which exhibited enzyme activity in the in vitro assay system. Furthermore, recombinant bovine PAF-AH was identified by western blot using human plasma PAF-AH antibody as a monomeric polypeptide with a molecular weight of approximately 43 kDa. This protein can be applied to in vivo models to test its protective role against the deleterious PAF actions.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed2004

InsP3-mediated intracellular calcium signalling is altered by expression of synaptojanin-1.

Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] plays an important physiological role as a precursor for the InsP3-mediated intracellular calcium (Ca2+) signalling cascade. It also regulates membrane trafficking, actin function and transmembrane proteins. SJ-1 (synaptojanin-1), a phosphoinositide phosphatase, regulates the turnover of a PtdIns(4,5)P2 pool involved in clathrin and actin dynamics at the cell surface. We tested the interrelationship of this pool with PtdIns(4,5)P2 pools involved in Ca2+ signalling by expressing in Chinese-hamster ovary cells full-length SJ-1 or its 5-Pase (inositol 5-phosphatase) domain. SJ-1 significantly attenuated the generation of Ca2+ oscillations induced by ATP and the 5-Pase domain mimicked this effect. These changes correlated with increased PtdIns(4,5)P2 phosphatase activity of cellular extracts. Overexpression of the endoplasmic reticulum-anchored PtdIns(4)P phosphatase Sac1 did not affect Ca2+ oscillations, although it increased the Ca2+ efflux rate from intracellular stores. The ability of SJ-1 to alter intracellular Ca2+ signalling indicates a close functional interrelationship between plasma membrane PtdIns(4,5)P2 pools that control actin and endocytosis and those involved in the regulation of specific spatio-temporal Ca2+ signals.

Adenosine Triphosphate↗

PubMed2004

Deoxypodophyllotoxin, a naturally occurring lignan, inhibits the passive cutaneous anaphylaxis reaction.

This study examined the effect of a podophyllotoxin derivative, deoxypodophyllotoxin (anthricin), which is a medicinal herb product isolated from Anthriscus sylvestris Hoffm. Deoxypodophyllotoxin was tested in a rat PCA (passive cutaneous anaphylaxis) assay by administering deoxypodophyllotoxin intraperitoneally (1.0 to 10 mg/kg, i.p.) and intravenously (0.25 to 1.0 mg/kg, i.v.). Deoxypodophyllotoxin dose-dependently inhibited the PCA reaction activated by anti-dinitrophenyl (DNP) IgE. The PCA inhibitory activity of deoxypodophyllotoxin was stronger than those of prednisolone and indomethacin, which were used as positive controls. These results suggest that deoxypodophyllotoxin may be beneficial in regulating the immediate-type allergic reaction.

Animals↗

PubMed2004

Inhibition of nitric oxide and tumor necrosis factor-alpha (TNF-alpha) production by propenone compound through blockade of nuclear factor (NF)-kappa B activation in cultured murine macrophages.

Lipopolysaccharide (LPS)-stimulated macrophages produce large amounts of nitric oxide (NO) by inducible nitric oxide synthase (iNOS). This is an important mechanism in macrophage-induced septic shock and inflammation. In the present study, we tested a synthetic propenone compound, 1-furan-2-yl-3-pyridin-2-yl-propenone (FPP-3) for its ability to inhibit the production of tumor necrosis factor-alpha (TNF-alpha) and an inducible enzyme, iNOS, in the LPS-stimulated murine macrophage-like cell line, RAW264.7. FPP-3 consistently inhibited nitric oxide (NO) and TNF-alpha production in a dose dependent manner, with IC(50) values of 10.0 and 13.1 microM, respectively. Western blotting probed with specific anti-iNOS antibodies showed that the decrease in quantity of the NO product was accompanied by a decrease in the iNOS protein level. In cells transiently transfected with nuclear factor (NF)-kappaB promoter-luciferase reporter construct, this compound clearly inhibited the LPS-stimulated NF-kappaB activation. Moreover, this compound inhibited IkappaB-alpha degradation in a concentration and time-dependent manner. These results indicate that FPP-3 inhibits NO production via inhibition of degradation of IkappaB-alpha through NF-kappaB activation.

Animals↗

PubMed2003

Degranulation and cytokine expression in human cord blood-derived mast cells cultured in serum-free medium with recombinant human stem cell factor.

Human cord blood-derived mast cells (HCMC) grown in medium with serum and recombinant human stem cell factor (rhSCF) with or without interleukin (IL)-6 are less mature than human skin mast cells (HSMC). We found that c-kit-positive HCMC cultured for 8-10 weeks with rhSCF in serum-free medium became sensitive to basic secretatogues and expressed the serine protease, chymase, which is preferentially expressed in HSMC. The HCMC release beta-hexosaminidase (beta-HEX) within 1 min of stimulation with compound 48/80 or substance P, and release was suppressed by pertussis toxin. Approximately 34% of the HCMC in the serum-free culture stained positively with chymase antibody. Chymase and c-kit levels, and responsiveness to basic secretagogues, increased substantially after an additional 2 weeks in a serum-free environment with rhIL-6 and rhSCF. Moreover, Fc(epsilon)RI-dependent activation of the HCMC resulted in induction of cytokines and cyclooxygenase-2. These results show that HCMC can differentiate into a phenotype morphologically and functionally similar to HSMC if exposed to SCF in serum-free medium.

Cell Degranulation↗

PubMed2003

Recombinant human (rh) stem cell factor and rhIL-4 stimulate differentiation and proliferation of CD3+ cells from umbilical cord blood and CD3+ cells enhance FcepsilonR1 expression on fetal liver-derived mast cells in the presence of rhIL-4.

We previously reported that rhIL-4 induced apoptosis and rhIL-6 mediated protection of human mast cells derived from cord blood mononuclear cells. Based on the result, we attempted to obtain the phenotypes and differentiation of CD3+ cells from cord blood by investigating their cell surface markers in the presence of rhSCF plus rhIL-4. The effect of co-cultured CD3+ cells on fetal liver mast cells (FLMCs) was also determined. Phenotypes from cord blood-derived cells were analyzed by flow cytometry and cell numbers were determined. Fetal liver mast cells were cultured with cord blood-derived cells (mainly CD3+) in the presence of rhSCF and/or rhIL-4 and were analyzed to determine cell number and expression of Kit+ and FcepsilonR1. The percentage of CD3+ cells from cord blood-derived cells on day 0 was about 41 +/- 13.5%, following monocytes and granulocytes. CD3+ cells increased in number (1.5-fold) and purity (90%), whereas other cell types did not survive. More than 60% of CD3+ cells from cord blood at day 0 were CD4(-)CD8-. These double-negative cells dramatically decreased by 1 week of culture, while CD4+CD8+ cells increased in number and purity through 3 weeks of culture, and then decreased as greater numbers of single-positive T cells emerged. We also found that FcepsilonR expression on FLMC increased in the presence of rhIL-4, but was not affected by the T cells that developed from cord blood mononuclear cells. The results indicate that IL-4, a Th2 type cytokine, together with rhSCF, can induce T cell proliferations, differentiation, and maturation from cord blood progenitor cells.

CD3 Complex↗

PubMed2003

Inhibitory effects of a new iridoid, patridoid II and its isomers, on nitric oxide and TNF-alpha production in cultured murine macrophages.

Patridoids I, II and IIA, are new iridoids isolated from the whole plants of Patrinia saniculaefolia. These compounds were examined by assessing their effects on the production of tumor necrosis factor-alpha (TNF-alpha) as well as by investigating the expression of two enzymes, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), in the lipopolysaccharide (LPS)-stimulated murine macrophage-like cell line, Raw 264.7. Among them, patridoid II consistently inhibited nitric oxide (NO) and TNF-alpha production in a dose-dependent manner, with IC (50) values of 14.1 and 17.6 microM, respectively. Western Blotting probed with specific anti-iNOS antibodies showed that the decrease in the quantity of the NO product was accompanied by a decrease in the iNOS protein level. However, all three patridoids did not affect the COX-2 protein expression level in the LPS-stimulated macrophages. In addition, the C-5 isomer of patridoid II, patridoid I, only slightly affected the production of NO. Moreover, the C-3 isomer of patridoid II, patridoid IIA, did not inhibit proinflammatory cytokines and NO production. These results suggest that the orientations of the C-3 and C-5 methoxy groups in the patridoids have a significant role in the expression of their biological activity.

Animals↗

PubMed2003

RacB regulates cytoskeletal function in Dictyostelium spp.

Thus far, 14 homologues of mammalian Rac proteins have been identified in Dictyostelium. It is unclear whether each of these genes has a unique function or to what extent they play redundant roles in actin cytoskeletal organization. To investigate the specific function of RacB, we have conditionally expressed wild-type (WT-RacB), dominant negative (N17-RacB), and constitutively activated (V12-RacB) versions of the protein. On induction, cells expressing V12-RacB stopped growing, detached from the surface, and formed numerous spherical surface protrusions while cells overexpressing WT-RacB became flattened on the surface. In contrast, cells overexpressing N17-RacB did not show any significant morphological abnormalities. The surface protrusions seen in V12-RacB cells appear to be actin-driven protrusions because they were enriched in F-actin and were inhibitable by cytochalasin A treatment. The protrusions in V12-RacB cells did not require myosin II activity, which distinguishes them from blebs formed by wild-type cells under stress. Finally, we examined the functional consequences of expression of wild-type and mutant RacB. Phagocytosis, endocytosis, and fluid phase efflux rates were reduced in all cell lines expressing RacB proteins but the greatest decrease was observed for cells expressing V12-RacB. From these results, we conclude that like other members of the Rho family, RacB induces polymerization of actin but the consequences of activation appear to be different from other Dictyostelium Rac proteins so far investigated, resulting in different morphological and functional changes in cells.

Actins↗

PubMed2003

Papyriflavonol A from Broussonetia papyrifera inhibits the passive cutaneous anaphylaxis reaction and has a secretory phospholipase A2-inhibitory activity.

Papyriflavonol A, a new prenylated flavonol isolated from Broussonetia papyrifera, selectively inhibits recombinant human secretory phospholipase A(2)s (sPLA(2)s). Papyriflavonol A was found to inhibit human group IIA and V sPLA(2)s potently and irreversibly in a dose-dependent manner, with respective IC(50) values of 3.9 and 4.5 microM. The inhibitory effects of papyriflavonol A against bovine group IB (IC(50) of 76.9 microM) and the human group X (IC(50) of 225 microM) sPLA(2)s were weaker than those against human group IIA and V sPLA(2)s, and human group IIF sPLA(2) was not inhibited. In addition, papyriflavonol A potently inhibited the stimulus-induced production of leukotriene C(4) with an IC(50) value of approximately 0.64 microM in mouse bone marrow-derived mast cells. In addition, papyriflavonol A significantly reduced IgE-dependent passive cutaneous anaphylaxis in rats. These results indicate that papyriflavonol A provides a basis for novel types of antiinflammatory drugs.

Animals↗

PubMed2002

Amphiphysin 2 (Bin1) and T-tubule biogenesis in muscle.

In striated muscle, the plasma membrane forms tubular invaginations (transverse tubules or T-tubules) that function in depolarization-contraction coupling. Caveolin-3 and amphiphysin were implicated in their biogenesis. Amphiphysin isoforms have a putative role in membrane deformation at endocytic sites. An isoform of amphiphysin 2 concentrated at T-tubules induced tubular plasma membrane invaginations when expressed in nonmuscle cells. This property required exon 10, a phosphoinositide-binding module. In developing myotubes, amphiphysin 2 and caveolin-3 segregated in tubular and vesicular portions of the T-tubule system, respectively. These findings support a role of the bilayer-deforming properties of amphiphysin at T-tubules and, more generally, a physiological role of amphiphysin in membrane deformation.

Animals↗

PubMed2002

Dynamin at actin tails.

Dynamin, the product of the shibire gene of Drosophila, is a GTPase critically required for endocytosis. Some studies have suggested a functional link between dynamin and the actin cytoskeleton. This link is of special interest, because there is evidence implicating actin dynamics in endocytosis. Here we show that endogenous dynamin 2, as well as green fluorescence protein fusion proteins of both dynamin 1 and 2, is present in actin comets generated by Listeria or by type I PIP kinase (PIPK) overexpression. In PIPK-induced tails, dynamin is further enriched at the interface between the tails and the moving organelles. Dynamin mutants harboring mutations in the GTPase domain inhibited nucleation of actin tails induced by PIPK and moderately reduced their speed. Although dynamin localization to the tails required its proline-rich domain, expression of a dynamin mutant lacking this domain also diminished tail formation. In addition, this mutant disrupted a membrane-associated actin scaffold (podosome rosette) previously shown to include dynamin. These findings suggest that dynamin is part of a protein network that controls nucleation of actin from membranes. At endocytic sites, dynamin may couple the fission reaction to the polymerization of an actin pool that functions in the separation of the endocytic vesicles from the plasma membrane.

Actins↗