Eunpyo Moon

Ajou University, Sŏul, Seoul, South Korea

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Publications (27)89.42 Total impact

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    ABSTRACT: Although the epidermal growth factor receptor (EGFR) is an established target in head-and-neck cancer (HNC), resistance to EGFR-targeted therapy mediated by various mechanisms has been reported. Therefore, a combination strategy to overcome resistance to EGFR mono-targeted therapy is clinically required. We have previously demonstrated that non-thermal atmospheric pressure plasma (NTP) induces death of various cancer cells, including oral squamous cancer (OSCC) cells. In this study, we report for the first time that combining NTP treatment with cetuximab led to inhibition of migration and invasion in cetuximab-resistant OSCC cells, which could be a promising strategy to overcome resistance to anti-EGFR therapy. NTP induced deactivation of NF-κB in SCCQLL1 cells, but not in MSKQLL1 cells. In addition, NTP increased the expression level of E-cadherin, and decreased those of vimentin, Slug, Snail, matrix metalloproteinase (MMP)-2, -9, and activities of MMPs. Moreover, NF-κB upregulation using cDNA diminished the combination effect of NTP on invasion, migration and related signals. Taken together, these results indicate that the combination of NTP with cetuximab can decrease invasiveness in cetuximab-resistant OSCCs through a novel mechanism involving the NF-κB pathway. These findings show the therapeutic potential of treatment that combines NTP and cetuximab in OSCC.
    Preview · Article · Dec 2015 · Scientific Reports
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    Jeahyuk Choi · Kwang-Hyun Baek · Eunpyo Moon

    Full-text · Dataset · Sep 2015
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    ABSTRACT: Purpose To determine the effects of nonthermal plasma (NTP) induced by helium (He) alone or He plus oxygen (O2) on the generation of reactive oxygen species (ROS) and cell death in anaplastic thyroid cancer cells. Materials and Methods NTP was generated in He alone or He plus O2 blowing through a nozzle by applying a high alternating current voltage to the discharge electrodes. Optical emission spectroscopy was used to identify various excited plasma species. The apoptotic effect of NTP on the anaplastic thyroid cancer cell lines, such as HTH83, U-HTH 7, and SW1763, was verified with annexin V/propidium staining and TUNEL assay. ROS formation after NTP treatment was identified with fluorescence-activated cell sorting with DCFDA staining. The mitogen-activated protein kinase pathways and caspase cascade were investigated to evaluate the molecular mechanism involved and cellular targets of plasma. Results NTP induced significant apoptosis in all three cancer cell lines. The plasma using He and O2 generated more O2-related species, and increased apoptosis and intracellular ROS formation compared with the plasma using He alone. NTP treatment of SW1763 increased the expression of phosphor-JNK, phosphor-p38, and caspase-3, but not phosphor-ERK. Apoptosis of SW1763 as well as expressions of elevated phosphor-JNK, phosphor-p38, and caspase-3 induced by NTP were effectively inhibited by intracellular ROS scavengers. Conclusion NTP using He plus O2 induced significant apoptosis in anaplastic cancer cell lines through intracellular ROS formation. This may represent a new promising treatment modality for this highly lethal disease.
    Full-text · Article · Nov 2014 · Yonsei Medical Journal
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    Jeahyuk Choi · Kwang-Hyun Baek · Eunpyo Moon
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    ABSTRACT: Antimicrobial peptides (AMPs) are small but effective cationic peptides with variable length. In previous study, four hexapeptides were identified that showed antimicrobial activities against various phytopathogenic bacteria. KCM21, the most effective antimicrobial peptide, was selected for further analysis to understand its modes of action by monitoring inhibitory effects of various cations, time-dependent antimicrobial kinetics, and observing cell disruption by electron microscopy. The effects of KCM21 on Gram-negative strain, Pseudomonas syringae pv. tomato DC3000 and Gram-positive strain, Clavibacter michiganensis subsp. michiganensis were compared. Treatment with divalent cations such as Ca(2+) and Mg(2+) inhibited the bactericidal activities of KCM21 significantly against P. syringae pv. tomato DC3000. The bactericidal kinetic study showed that KCM21 killed both bacteria rapidly and the process was faster against C. michiganensis subsp. michiganensis. The electron microscopic analysis revealed that KCM21 induced the formation of micelles and blebs on the surface of P. syringae pv. tomato DC3000 cells, while it caused cell rupture against C. michiganensis subsp. michiganensis cells. The outer membrane alteration and higher sensitivity to Ca(2+) suggest that KCM21 interact with the outer membrane of P. syringae pv. tomato DC3000 cells during the process of killing, but not with C. michiganensis subsp. michiganensis cells that lack outer membrane. Considering that both strains had similar sensitivity to KCM21 in LB medium, outer membrane could not be the main target of KCM21, instead common compartments such as cytoplasmic membrane or internal macromolecules might be a possible target(s) of KCM21.
    Full-text · Article · Sep 2014 · The plant pathology journal
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    ABSTRACT: Staphylococcus aureus is important food-borne pathogen in agricultural products consumed in a fresh state. The antimicrobial activities of staphylococci isolated from vegetables in Korea against S. aureus were investigated. Coagulase-negative staphylococci (CNS) isolates (12) with antimicrobial activities against S. aureus were identified as S. xylosus, pasteuri, and epidermidis. CNS isolates exhibited antimicrobial activities against Gram-positive bacteria. Inactivation of S. pasteuri antimicrobial activity by proteases suggested that the substances evaluated were antimicrobial peptides or bacteriocins. None of the S. pasteuri isolates possessed homologous DNA fragments known to be bacteriocin genes, except for nukacin. The nukM gene that encodes a post-translational modification enzyme in the nukacin gene cluster was not detected in S. pasteuri isolates. S. pasteuri probably produces one or more new antimicrobial substances.
    No preview · Article · Jun 2014 · Food science and biotechnology
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    ABSTRACT: Plasma, the fourth state of matter, is defined as a partially or completely ionized gas that includes a mixture of electrons and ions. Advances in plasma physics have made it possible to use non-thermal atmospheric pressure plasma (NTP) in cancer research. However, previous studies have focused mainly on apoptotic cancer cell death mediated by NTP as a potential cancer therapy. In this study, we investigated the effect of NTP on invasion or metastasis, as well as the mechanism by which plasma induces anti-migration and anti-invasion properties in human thyroid papillary cancer cell lines (BHP10-3 and TPC1). Wound healing, pull-down, and Transwell assays demonstrated that NTP reduced cell migration and invasion. In addition, NTP induced morphological changes and cytoskeletal rearrangements, as detected by scanning electron microscopy and immunocytochemistry. We also examined matrix metalloproteinase (MMP)-2/-9 and urokinase-type plasminogen activator (uPA) activity using gelatin zymography, uPA assays and RT-PCR. FAK, Src, and paxillin expression was detected using Western blot analyses and immunocytochemistry. NTP decreased FAK, Src, and paxillin expression as well as MMP/uPA activity. In conclusion, NTP inhibited the invasion and metastasis of BHP10-3 and TPC1 cells by decreasing MMP-2/-9 and uPA activities and rearranging the cytoskeleton, which is regulated by the FAK/Src complex. These findings suggest novel actions for NTP and may aid in the development of new therapeutic strategies for locally invasive and metastatic cancers.
    Full-text · Article · Mar 2014 · PLoS ONE
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    ABSTRACT: Nonthermal plasma (NTP) is generated by ionization of neutral gas molecules, which results in a mixture of energy particles including electrons and ions. Recent progress in the understanding of NTP has led to its application in the treatment of various diseases, including cancer. However, the molecular mechanisms of NTP-induced cell death are unclear. The purpose of this study was to evaluate the molecular mechanism of NTP in the induction of apoptosis of head and neck cancer (HNC) cells. The effects of NTP on apoptosis were investigated using MTT, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling, Annexin V assays, and western blot analysis. The cells were examined for production of reactive oxygen species (ROS) using DCFCA or MitoSOX staining, intracellular signaling, and an animal model. NTP reduced HNC cell viability in a dose-dependent manner and induced apoptosis. NTP resulted in alteration of mitochondrial membrane potential and accumulation of intracellular ROS generated from the mitochondria in HNC cells. Blockade of ROS production by N-acetyl-L-cysteine inhibited NTP-induced apoptosis. NTP led to the phosphorylation of c-JUN N-terminal kinase (JNK) and p38, but not extracellular-regulated kinase. Treatment with JNK and p38 inhibitors alleviated NTP-induced apoptosis via ROS generation. Taken together, these results show that NTP induced apoptosis of HNC cells by a mechanism involving MAPK-dependent mitochondrial ROS. NTP inhibited the growth of pre-established FaDu tumors in a nude mouse xenograft model and resulted in accumulation of intracellular ROS. In conclusion, NTP induced apoptosis in HNC cells through a novel mechanism involving MAPK-mediated mitochondrial ROS. These findings show the therapeutic potential of NTP in HNC.
    Full-text · Article · Feb 2014 · Cell Death & Disease
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    ABSTRACT: Recent advances in physics have made possible the use of non-thermal atmospheric pressure plasma (NTP) in cancer research. Although increasing evidence suggests that NTP induces death of various cancer cell types, thus offering a promising alternative treatment, the mechanism of its therapeutic effect is little understood. In this study, we report for the first time that NTP led to apoptotic cell death in oral cavity squamous cell carcinoma (OSCC). Interestingly, NTP induced a sub-G1 arrest in p53 wild-type OSCCs, but not in p53-mutated OSCCs. In addition, NTP increased the expression levels of ATM, p53 (Ser 15, 20 and 46), p21, and cyclin D1. A comet assay, Western blotting and immunocytochemistry of γH2AX suggested that NTP-induced apoptosis and sub-G1 arrest were associated with DNA damage and the ATM/p53 signaling pathway in SCC25 cells. Moreover, ATM knockdown using siRNA attenuated the effect of NTP on cell death, sub-G1 arrest and related signals. Taken together, these results indicate that NTP induced apoptotic cell death in p53 wild-type OSCCs through a novel mechanism involving DNA damage and triggering of sub-G1 arrest via the ATM/p53 pathway. These findings show the therapeutic potential of NTP in OSCC.
    No preview · Article · Jan 2014 · Archives of Biochemistry and Biophysics
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    ABSTRACT: The plasma jet has been proposed as a novel therapeutic method for cancer. Anticancer activity of plasma has been reported to involve mitochondrial dysfunction. However, what constituents generated by plasma is linked to this anticancer process and its mechanism of action remain unclear. Here, we report that the therapeutic effects of air plasma result from generation of reactive oxygen/nitrogen species (ROS/RNS) including H2O2, Ox, OH(-), •O2, NOx, leading to depolarization of mitochondrial membrane potential and mitochondrial ROS accumulation. Simultaneously, ROS/RNS activate c-Jun NH2-terminal kinase (JNK) and p38 kinase. As a consequence, treatment with air plasma jets induces apoptotic death in human cervical cancer HeLa cells. Pretreatment of the cells with antioxidants, JNK and p38 inhibitors, or JNK and p38 siRNA abrogates the depolarization of mitochondrial membrane potential and impairs the air plasma-induced apoptotic cell death, suggesting that the ROS/RNS generated by plasma trigger signaling pathways involving JNK and p38 and promote mitochondrial perturbation, leading to apoptosis. Therefore, administration of air plasma may be a feasible strategy to eliminate cancer cells.
    Full-text · Article · Jan 2014 · PLoS ONE
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    ABSTRACT: Recent advances in physics have made possible the use of non-thermal atmospheric pressure plasma (NTP) in cancer research. Although increasing evidence suggests that NTP induces death of various cancer cell types, thus offering a promising alternative treatment, the mechanism of its therapeutic effect is little understood. In this study, we report for the first time that NTP led to apoptotic cell death in oral cavity squamous cell carcinoma (OSCC). Interestingly, NTP induced a sub-G1 arrest in p53 wild-type OSCCs, but not in p53-mutated OSCCs. In addition, NTP increased the expression levels of ATM, p53 (Ser 15, 20 and 46), p21, and cyclin D1. A comet assay, Western blotting and immunocytochemistry of γH2AX suggested that NTP-induced apoptosis and sub-G1 arrest were associated with DNA damage and the ATM/p53 signaling pathway in SCC25 cells. Moreover, ATM knockdown using siRNA attenuated the effect of NTP on cell death, sub-G1 arrest and related signals. Taken together, these results indicate that NTP induced apoptotic cell death in p53 wild-type OSCCs through a novel mechanism involving DNA damage and triggering of sub-G1 arrest via the ATM/p53 pathway. These findings show the therapeutic potential of NTP in OSCC.
    No preview · Article · Jan 2014 · Archives of Biochemistry and Biophysics
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    ABSTRACT: GC-MS analysis of a hot water extract of Herba Pogostemonis (HP) revealed the presence of 131 compounds. HP slightly inhibited Salmonella Typhimurium bacteria in culture and stimulated uptake of the bacteria into RAW 264.7 murine macrophage cells as indicated by both increased fluorescence from internalized FITC-dextran and increased colony-forming unit (CFU) counts of the lysed macrophages. Postinfection, the HP-treated cells showed lower bacterial counts than the control. HP elicited altered morphology, elevated inducible NO synthase (iNOS) mRNA, and reduced pro-inflammatory cytokine expression in macrophage cells. Salmonella induced increased expression of iNOS mRNA, cognate polypeptides, and NO. Histology of mice infected with a sublethal dose (1 × 10(4) CFU) of Salmonella showed that intraperitoneally administered HP protected against necrosis of the liver, a biomarker of in vivo salmonellosis. The lifespan of mice infected with a lethal dose (1 × 10(5) CFU) was significantly extended. These results suggest that the activity of HP against bacterial infection in mice occurs through the activation of innate immune macrophage cells. The relationship of composition of HP to bioactivity is discussed.
    No preview · Article · Nov 2012 · Journal of Agricultural and Food Chemistry
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    ABSTRACT: The aim of this study is to determine the protective effect of a liquid rice hull smoke extract (RHSE) against type 2 diabetes (T2D) in mice induced by a high-fat diet. As compared to the control group of mice on a high-fat diet (HFD), feeding the HFD supplemented with 0.5% or 1% RHSE for 7 weeks resulted in significantly reduced blood glucose and triglyceride and cholesterol concentrations, higher serum insulin levels, and improved glucose tolerance, as assessed by an oral glucose tolerance assay. The hypoglycemic effect of RHSE was accompanied by changes in enzyme activities and cognate gene expression assessed using RT-PCR. Among the glucose metabolism regulating genes evaluated, hepatic glucokinase (GCK), the glucose transporters GLUT2 and GLUT4, and peroxisome proliferator-activated receptor-γ (PPAR-γ) were up-regulated, whereas glucose-6-phosphatase (G6 Pase) and phosphoenolpyruvate carboxykinase (PEPCK) were down-regulated in the liver of mice with RHSE-supplementation. These changes resulted in restoration of glucose-regulating activities to normal control levels. Histopathology showed that a high-fat diet intake also induced liver necrosis and damage of the islet of Langerhans in the pancreas, whereas RHSE supplementation restored necrotic damage to normal levels. Immunohistochemistry showed that RHSE supplementation can restore the reduced insulin-producing β-cell population in islet of Langerhans associated with a high-fat diet intake to nondiabetic normal control levels in a dose-dependent manner. RHSE-supplemented food could protect insulin-producing islet cells against damage triggered by oxidative stress and local inflammation associated with diabetes.
    Preview · Article · Jul 2012 · Journal of Agricultural and Food Chemistry
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    ABSTRACT: The present study investigated the antibacterial effect of four extracts from the fruitbody of the edible medicinal mushroom Hericium erinaceus (hot water extract, HWE; microwave/50% ethanol extract, MWE; acid extract, ACE; and alkaline extract, AKE) against murine salmonellosis. The extracts had no effect on Salmonella ser. Typhimurium growth in culture. Nor were the extracts toxic to murine macrophage cells, RAW 264.7. HWE and MWE stimulated uptake of the bacteria into the macrophage cells as indicated by increased colony-forming unit (CFU) counts of the contents of the lysed macrophages infected with Salmonella Typhimurium for 30 and 60 min. Two hours postinfection, the bacterial counts increased in the macrophages, but 4 and 8 h postinfection the HWE- and MWE-treated cells showed greater activity against the bacteria than the control. HWE- and MWE-treated noninfected macrophages had altered morphology and elevated inducible nitric oxide (NO) synthase (iNOS) mRNA expression. In the presence of S. Typhimurium, iNOS mRNA expression was further increased, accompanied by an increase in NO production. Histology assays of the livers of mice infected with a sublethal dose (1 × 10(4) CFU) of S. Typhimurium showed that HWE and MWE, administered by daily intraperitoneal injection, protected against necrosis of the liver, a biomarker of in vivo salmonellosis. The lifespans of mice similarly infected with a lethal dose of S. Typhimurium (1 × 10(5) CFU) were significantly extended by HWE and MWE. β-Glucan, known to stimulate the immune system, was previously found to be present in high amounts in the active extracts. These results suggest that the mushroom extract activities against bacterial infection in mice occur through the activation of innate immune cells.
    No preview · Article · May 2012 · Journal of Agricultural and Food Chemistry
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    ABSTRACT: CREB mediates the transcriptional effects of glucose and incretin hormones in insulin-target cells and insulin-producing β-cells. Although the inhibition of CREB activity is known to decrease the β-cell mass, it is still unknown what factors inversely alter the CREB signaling pathway in β-cells. Here, we show that β-cell dysfunctions occurring in chronic hyperglycemia are not caused by simple inhibition of CREB activity but rather by the persistent activation of CREB due to decreases in protein phophatase PP2A. When freshly isolated rat pancreatic islets were chronically exposed to 25 mM (high) glucose, the PP2A activity was reduced with a concomitant increase in active pCREB. Brief challenges with 15 mM glucose or 30 µM forskolin after 2 hour fasting further increased the level of pCREB and consequently induced the persistent expression of ICER. The excessively produced ICER was sufficient to repress the transcription of NeuroD, insulin, and SUR1 genes. In contrast, when islets were grown in 5 mM (low) glucose, CREB was transiently activated in response to glucose or forskolin stimuli. Thus, ICER expression was transient and insufficient to repress those target genes. Importantly, overexpression of PP2A reversed the adverse effects of chronic hyperglycemia and successfully restored the transient activation of CREB and ICER. Conversely, depletion of PP2A with siRNA was sufficient to disrupt the negative feedback regulation of CREB and induce hyperglycemic phenotypes even under low glucose conditions. Our findings suggest that the failure of the negative feedback regulation of CREB is the primary cause for β-cell dysfunctions under conditions of pathogenic hyperglycemia, and PP2A can be a novel target for future therapies aiming to protect β-cells mass in the late transitional phase of non-insulin dependent type 2 diabetes (NIDDM).
    Full-text · Article · Apr 2012 · PLoS ONE
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    ABSTRACT: The plasma jet has been proposed as a novel therapeutic method for anticancer treatment. However, its biological effects and mechanism of action remain elusive. Here, we investigated its cell death effects and underlying molecular mechanisms, using air and N₂ plasma jets from a micro nozzle array. Treatment with air or N₂ plasma jets caused apoptotic death in human cervical cancer HeLa cells, simultaneously with depolarization of mitochondrial membrane potential. In addition, the plasma jets were able to generate reactive oxygen species (ROS), which function as surrogate apoptotic signals by targeting the mitochondrial membrane potential. Antioxidants or caspase inhibitors ameliorated the apoptotic cell death induced by the air and N₂ plasma jets, suggesting that the plasma jet may generate ROS as a proapoptotic cue, thus initiating mitochondria-mediated apoptosis. Taken together, our data suggest the potential employment of plasma jets as a novel therapy for cancer.
    Preview · Article · Nov 2011 · PLoS ONE
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    ABSTRACT: The human genome contains genes encoding for over 40 different types of kinesin and kinesin-like proteins. Of these, the functions of 13 kinesins remain uncharacterized. In this study, we constructed a plasmid containing the ORF of KIF18B and revealed that the KIF18B message of approximately 3kb is expressed in a tissue- and cell type-specific manners. A polypeptide of 842 amino acids was deduced from the ORF sequence. We identified another form of 873 amino acids which arises from alternative splicing at the C-terminal end. We also generated an anti-KIF18B antibody which detects a protein band of 120kDa. Western analyses showed that the protein level of KIF18B is elevated at late G(2) through metaphase, very similar to cyclin B1. Immunocytochemical staining revealed that the KIF18B protein is present predominantly in the nucleus and to a lesser extent in the cytoplasm of interphase cells. During mitosis, most KIF18B was found to be closely associated with astral microtubules emanating from the spindle pole during prometaphase and metaphase. Meanwhile, KIF18B was not detected at anaphase and telophase, consistent with the Western blotting data. The nuclear localization signal was roughly determined by using several EGFP-tagged deletion mutants of KIF18B. Together, the expression of KIF18B is regulated in a cell cycle-dependent manner and therefore may play an important role(s) in cell division.
    Full-text · Article · Oct 2010 · Gene
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    Jaehyuk Choi · Eunpyo Moon
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    ABSTRACT: Antimicrobial peptides (AMPs) are considered to be a promising alternative to conventional antibiotics for future generations. We identified four novel hexapeptides with antimicrobial activity: KCM11 (TWWRWW-NH(2)), KCM12 (KWRWIW-NH(2)), KCM21 (KWWWRW-NH(2)), and KRS22 (WRWFIH-NH(2)), through positional scanning of a synthetic peptide combinatorial library (PS-SCL). The ability of these peptides to inhibit the growth of a variety of bacteria and unicellular fungi was evaluated. KCM11 and KRS22 preferentially inhibited the normal growth of fungal strains, whereas KCM12 and KCM21 were more active against bacterial strains. Bactericidal activity was addressed in a clear zone assay against phytopathogenic bacteria, including Pectobacterium spp., Xanthomonas spp., Pseudomonas spp., etc. KCM21 showed the highest activity and was effective against a wide range of target organisms. Application of KCM21 with inoculation of Pectobacterium carotovorum subsp. carotovorum on detached cabbage leaves resulted in an immune phenotype or a significant reduction in symptom development, depending on the peptide concentration. Cytotoxicity of the four hexapeptides was evaluated in mouse and human epithelial cell lines using an MTT test. The results revealed a lack of cytotoxic effects.
    Full-text · Article · Sep 2009 · Journal of Microbiology and Biotechnology
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    ABSTRACT: Fifty-four Pectobacterium carotovorum subsp. carotovorum strains isolated in Korea were characterized by a spectrum of antibacterial activities against 7 indicator strains chosen to represent various regions and host plants. All P. carotovorum subsp. carotovorum isolates tested could be grouped into 4 classes depending on the pattern of antibacterial substance production. All tested strains had DNA fragment(s) homologous to the genes encoding carotovoricin and 21 of them had genes homologous to DNA invertase. Sixteen strains had genes homologous to the genes encoding carocin S1. Several isolates produced antibacterial substances active against strains in Brenneria, Pantoea, and Pectobacterium genera that belonged formerly to the genus Erwinia. Strains in Pseudomonas or Xanthomonas sp. were not sensitive to the antibacterial substances produced by P. carotovorum subsp. carotovorum, except for X. albilineans that was sensitive to antibacterial substances produced by most strains in P. carotovorum subsp. carotovorum and P. betavasculorum KACC10056. These results demonstrated the diverse patterns of antibacterial substance production and the possibility of the existence of new antibacterial substance(s) produced by P. carotovorum subsp. carotovorum isolated in Korea.
    Full-text · Article · Feb 2009 · Journal of Microbiology and Biotechnology
  • Eunjung Roh · Sunggi Heu · Eunpyo Moon
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    ABSTRACT: Xanthomonas axonopodis pv. glycines produces bacteriocins called glycinecin, and two glycinecin genes, glyA and glyR, were reported previously. In this paper, we describe genomic distribution and variation of the glyR gene revealed by extensive Southern hybridization analysis. In contrast to the glyA gene present only in X. axonopodis pv. glycines, the glyR gene was found to be distributed widely in all the pathovars of Xanthomas genus. It was also found that the glyR gene is a multigene family while the glyA is a single copy gene. Moreover, the copy number and the variation of the glyR multigene are unique to each pathovar of Xanthomonas. The uniqueness can be easily detected by the patterns resulted from Southern hybridization using the genomic digests. Thus, we suggest the glyR gene can serve as a useful genus-specific and pathovar-specific DNA marker for Xanthomonas. One of the glyR homologs was further isolated from X. axonopodis pv. glycines, and analyzed to be functional with strong inhibitory activity against several members of Xanthomonas.
    No preview · Article · Jan 2009 · The Journal of Microbiology
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    ABSTRACT: Signal transduction pathway and a new function of TIS21/BTG2/PC3 were investigated in p53 null U937 cells; Expression of TIS21 by 12-O-tetradecanoyl phorbol-13-acetate (TPA) stimulation was mediated by PKC-delta activation, however, was strongly inhibited by cPKC isozymes. When U937 cells were treated with TPA+Go6976, but not TPA+Go6850, the level of TIS21 mRNA was maintained over that of TPA alone. When analyzed by FACS, TPA-induced G2/M arrest was significantly inhibited by Go6850, but not by Go6976, suggesting the involvement of TIS21 and nPKC isozymes. Indeed, PKC-delta was found to be a regulator of the G2/M arrest and TIS21 expression, confirmed by employing rottlerin and dnPKC-delta experiments. In vivo accumulation of TIS21 protein significantly induced cell death through caspase 3 activation, which was supported further by degradations of procaspase 3, full-length PKC-delta, pRB, and p21(WAF1) in TIS21DeltaC expresser. When the cells were synchronized by nocodazole, TIS21 overexpressers inhibited degradations of cyclin A and cyclin B1 in 3 h after release from the synchronization. Furthermore, TIS21 inhibited cyclin B1-Cdc2 binding and its kinase activity in vivo. In summary, TPA-induced TIS21 mRNA expression is mediated by PKC-delta, and TIS21 induces G2/M arrest and cell death by inhibiting cyclin B1-Cdc2 binding and the kinase activity through its binding to Cdc2.
    Preview · Article · Oct 2004 · Experimental Cell Research

Publication Stats

365 Citations
89.42 Total Impact Points

Institutions

  • 1999-2015
    • Ajou University
      • • Department of Life Sciences
      • • Department of Anatomy
      • • Department of Electrical and Computer Engineering
      • • College of Natural Sciences
      • • Department of Medicine
      Sŏul, Seoul, South Korea
  • 2000
    • California Institute of Technology
      • Division of Biology
      Pasadena, CA, United States