Gi-Ho Sung

Genipin as a novel chemical activator of EBV lytic cycle

Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus that causes acute infection and establishes life-long latency. EBV causes several human cancers, including Burkitt’s lymphoma, nasopharyngeal and gastric carcinoma. Antiviral agents can be categorized as virucides, antiviral chemotherapeutic agents, and immunomodulators. Most antiviral agents affect actively replicating viruses, but not their latent forms. Novel antiviral agents must be active on both the replicating and the latent forms of the virus. Gardenia jasminoides is an evergreen flowering plant belonging to the Rubiaceae family and is most commonly found growing wild in Vietnam, Southern China, Taiwan, Japan, Myanmar, and India. Genipin is an aglycone derived from an iridoid glycoside called geniposide, which is present in large quantities in the fruit of G. jasminoides. In this study, genipin was evaluated for its role as an antitumor and antiviral agent that produces inhibitory effects against EBV and EBV associated gastric carcinoma (EBVaGC). In SNU719 cells, one of EBVaGCs, genipin caused significant cytotoxicity (70 μM), induced methylation on EBV C promoter and tumor suppressor gene BCL7A, arrested cell-cycle progress (S phases), upregulated EBV latent/lytic genes in a dose-dependent manner, stimulated EBV progeny production, activated EBV F promoter for EBV lytic activation, and suppressed EBV infection. These results indicated that genipin could be a promising candidate for antiviral and antitumor agents against EBV and EBVaGC.

Kaempferol, a dietary flavonoid, ameliorates acute inflammatory and nociceptive symptoms in gastritis, pancreatitis, and abdominal pain

Kaempferol (KF) is the most abundant polyphenol in tea, fruits, vegetables, and beans. However, little is known about its in vivo anti-inflammatory efficacy and mechanisms of action. To study these, several acute mouse inflammatory and nociceptive models, including gastritis, pancreatitis, and abdominal pain were employed. Kaempferol was shown to attenuate the expansion of inflammatory lesions seen in ethanol (EtOH)/HCl- and aspirin-induced gastritis, LPS/caerulein (CA) triggered pancreatitis, and acetic acid-induced writhing.

Mushroom Flora of Ulleung-gun and a Newly Recorded Bovista Species in the Republic of Korea

Abstract We conducted five times surveys, in June, September and October in 2012; June and September 2013, to catalog the mushroom flora in Ulleung-gun, Republic of Korea. More than 400 specimens were collected, and 317 of the specimens were successfully sequenced using the ribosomal DNA internal transcribed spacer barcode marker. We also surveyed the morphological characteristics of the sequenced specimens. The specimens were classified into 2 phyla, 7 classes, 21 orders, 59 families, 122 genera, and 221 species, and were deposited in the herbarium of Korea National Arboretum. Among the collected species, 72% were saprophytic, 25% were symbiotic, and 3% were parasitic. The most common order was Agaricales (189 specimens, 132 species), followed by Polyporales (47 specimens, 27 species), Russulales (31 specimens, 22 species), Boletales (10 specimens, 7 species), and so on. Herein, we also reported the first Bovista species in Korea, which was collected from Dokdo, the far-eastern island of Korea.

Regulation of a phenylalanine ammonia lyase (BbPAL) by calmodulin in response to environmental changes in the entomopathogenic fungus Beauveria bassiana

Phenylalanine ammonia lyase (PAL, E.C. 4.3.1.5) catalyses the deamination of L -phenylalanine to trans-cinnamic acid and ammonia, facilitating a critical step in the phenylpropanoid pathway that produces a variety of secondary metabolites. In this study, we isolated BbPAL gene in the entomopathogenic fungus Beauveria bassiana. According to multiple sequence alignment, homology modelling and in vitrou2005PAL activity, we demonstrated that BbPAL acts as a typical PAL enzyme in B. bassiana. BbPAL interacted with calmodulin (CaM) in vitro and in vivo, indicating that BbPAL is a novel CaM-binding protein. The functional role of CaM in BbPAL action was to negatively regulate the BbPAL activity in B.u2009bassiana. High-performance liquid chromatography analysis revealed that L -phenylalanine was reduced and trans-cinnamic acid was increased in response to the CaM inhibitor W-7. Dark conditions suppressed BbPAL activity in B.u2009bassiana, compared with light. In addition, heat and cold stresses inhibited BbPAL activity in B.u2009bassiana. Interestingly, these negative effects of BbPAL activity by dark, heat and cold conditions were recovered by W-7 treatment, suggesting that the inhibitory mechanism is mediated through stimulation of CaM activity. Therefore, this work suggests that BbPAL plays a role in the phenylpropanoid pathway mediated by environmental stimuli via the CaM signalling pathway.

Identification of calmodulin binding proteins in the entomopathogenic fungus Beauveria bassiana

Calmodulin (CaM) is a primary Ca2+ receptor and plays a pivotal role in a variety of cellular responses in eukaryotes. Even though a large number of CaM-binding proteins are well known in yeast, plants, and animals, little is known regarding CaM-targeted proteins in filamentous fungi. To identify CaM-binding proteins in filamentous fungi, we used a proteomics method coupled with co-immunoprecipitation (CoIP) and MALDI-TOF/TOF mass spectrometry (MS) in Beauveria bassiana. Through this method, we identified ten CaM-binding proteins in B. bassiana. One of the CaM-targeted proteins was the heat shock protein 70 (BbHSP70) in B. bassiana. Our biochemical study showed that ATP inhibits the molecular interaction between BbHSP70 and CaM, suggesting a regulatory mechanism between CaM and ATP for regulating BbHSP70.

Studies on seasonal dynamics of soil-higher fungal communities in Mongolian oak-dominant Gwangneung forest in Korea.

We surveyed macrofungi biweekly at defined plots from April to December in 2014, in the Mongolian oak-dominant forest, Gwangneung Forest, Pochen-si, Korea, and analyzed a soilhigher fungal diversity during four seasons (represented by April, August, October, and December). Based on morphological observation of collected specimens, the collected macrofungi were classified into 2 phyla 3 classes 7 orders, 14 families, 21 genera, and 33 species (36 specimens). DNA-based community analyses indicated that soil-higher fungi were classified into 2 phyla, 18 classes, 49 orders, 101 families, and 155 genera (83,360 sequence reads), defined herein as 155 genus-level operational taxonomic units (GOTUs). In the present study, we evaluated and discussed the fungal diversity in seasonal dynamics and soil layers based on collected macrofungi and pyrosequencing data while considering environmental parameters (pH, exchangeable K, T-P, NH4+, NO3-, OM, WR, TOC, and T-N). Moreover, principal components analysis (PCA) showed distinct clusters of the GOTU assemblage associated with the seasons.

Species identity of Phellinus linteus (sanghuang) extensively used as a medicinal mushroom in Korea

Sanghuang is a medicinal mushroom that has gained particular attention in Korea. It has been extensively studied for the past few decades as a natural immune booster and cancer suppressor. Although the scientific name, Phellinus linteus, has been commonly used to refer to the sanghuang mushroom, the species identity of sanghuang has been called into question due to the ambiguity of its circumscription and the inadequacy of morphological distinctions within allied species. Because the species concept of sanghuang has been elucidated by recent molecular phylogenetic studies, it has become necessary to clarify the taxonomic positions of sanghuang strains extensively utilized in Korea. We conducted a phylogenetic analysis of 74 strains belonging to the P. linteus-baumii complex based on ITS nrDNA sequences. Parental stains of sanghuang varieties formally registered in the Korea Seed & Variety Service, including ASI 26046 (Corea sanghuang), 26114 (Boolro), and 26115 (HK 1-ho) were grouped with Sanghuangporus sanghuang instead of P. linteus in the inferred phylogeny.

Beauvericin synthetase contains a calmodulin binding motif in the entomopathogenic fungus Beauveria bassiana

Beauvericin is a mycotoxin which has insecticidal, anti-microbial, anti-viral and anti-cancer activities. Beauvericin biosynthesis is rapidly catalyzed by the beauvericin synthetase (BEAS) in Beauveria bassiana. Ca2+ plays crucial roles in multiple signaling pathways in eukaryotic cells. These Ca2+ signals are partially decoded by Ca2+ sensor calmodulin (CaM). In this report, we describe that B. bassiana BEAS (BbBEAS) can interact with CaM in a Ca2+-dependent manner. A synthetic BbBEAS peptide, corresponding to the putative CaM-binding motif, formed a stable complex with CaM in the presence of Ca2+. In addition, in vitro CaM-binding assay revealed that the His-tagged BbBEAS (amino acids 2421-2538) binds to CaM in a Ca2+-dependent manner. Therefore, this work suggests that BbBEAS is a novel CaM-binding protein in B. bassiana.

Evaluation of a new matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system for the identification of yeast isolation

Currently, three commercial in vitro diagnostic matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) systems are widely used in clinical laboratories. The ASTA MicroIDSys system (ASTA Inc, South Korea) is a newly developed MALDI‐TOF MS system used for the identification of pathogenic microorganisms. In the present study, we assessed the performance of the ASTA MALDI‐TOF MS system for the identification of pathogenic yeast from clinical samples.

Pancreatic-cancer-cell-derived trefoil factor 2 impairs maturation and migration of human monocyte-derived dendritic cells in vitro

ABSTRACT Pancreatic cancer is a challenging disease with a high mortality rate. While the importance of crosstalk between cancer and immune cells has been well documented, the understanding of this complex molecular network is incomplete. Thus, identification of the secreted proteins contributing to the immunosuppressive microenvironment in pancreatic cancer is crucial for effective diagnosis and/or therapy. We utilized a public microarray dataset (GSE16515) from the Gene Expression Omnibus database to identify genes for secreted proteins in pancreatic cancer. RT–PCR and ELISA of the pancreatic cancer cell lines validated the cellular origin of the selected genes. For functional assay of the selected proteins, we utilized human-monocyte-derived dendritic cells (DCs). From the list of the secreted proteins, trefoil factor 2 (TFF2) was further examined as a potential chemokine/cytokine. While TFF2 did not significantly affect the phenotypic maturation and the allostimulatory capacity of DCs, TFF2 preferentially attracted immature (but not mature) DCs and inhibited their endocytic activity. Our data suggest that TFF2 from pancreatic cancer cells may attract immature DCs and affect the initial stage of DC maturation, thereby contributing to the induction of immune tolerance against pancreatic cancer.