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O-Yu Kwon

Publications and source records attributed to O-Yu Kwon.

13 recordsLinked to original sources
PubMed2006

Cryptococcus mujuensis sp. nov. and Cryptococcus cuniculi sp. nov., basidiomycetous yeasts isolated from wild rabbit faeces.

Two previously undescribed anamorphic yeasts, strains T-11(T) and T-26(T), recovered from wild rabbit faecal pellets collected in Muju, Korea, were identified using phenotypic and molecular taxonomic methods. The isolates were characterized by the proliferation of budding cells, positive diazonium blue B and urease reactions, the presence of Q-10 as the major ubiquinone, the presence of xylose in whole-cell hydrolysates and the inability to ferment sugars. Phylogenetic analyses based on 26S rRNA gene partial sequences revealed that strain T-11(T) was located in the Bulleromyces clade and was related to Sirobasidium intermedium, Tremella exigua, Cryptococcus cellulolyticus and Bullera pseudoalba. Strain T-26(T) was located in the Mesenterica clade and was closely related to Cryptococcus sp. F6 and Cryptococcus heveanensis CBS 8976. Sequence divergence values of more than 4 % from other described Cryptococcus species, together with the phenotypic differences, showed that the isolated yeasts represent previously unrecognized members of this genus. Therefore, two novel yeast species are proposed: Cryptococcus mujuensis sp. nov., with strain T-11(T) (=KCTC 17231(T)=CBS 10308(T)) as the type strain, and Cryptococcus cuniculi sp. nov., with strain T-26(T) (=KCTC 17232(T)=CBS 10309(T)) as the type strain.

Animals↗
PubMed2005

Galatosylation and sialylation of mammalian glycoproteins produced by baculovirus-madiated gene expression in insect cells.

The baculovirus expression vector system (BEVS) is used extensively for the production of proteins from exogenous cDNAs. However, BEVS is not ideal for pharmaceutical production of glycoproteins owing to the properties of the N-glycans in the expressed products and that insect cells lack several of the enzymes required for mammalian-type N-glycan synthesis. This study describes the effective mammalian-like production of glycoproteins, such as beta-1,4-galactosyltransferase and alpha-2,6-sialyltransferase, in the insect cell line Sf9.

Animals↗
PubMed2005

Changes in cellular secretory processing during baculovirus infection.

In the baculovirus expression vector system (BEVS), secretory green fluorescent protein (sGFP) transcripts were expressed from day 2 to day 5 post-infection (p.i.), while transcripts of the endoplasmic reticulum (ER) molecular chaperone Bombyx mori protein disulfide isomerase (bPDI) were measurable in mock cells and in cells at day 1 p.i. The GFP was expressed from day 3 to day 5 p.i. whereas the levels of two ER chaperone proteins, bPDI and calnexin, decreased from day 3 p.i. and were not detected from day 4 p.i. These findings suggest that the rate-limited expression of ER molecular chaperones is strongly associated with the maximal expression of exogenous proteins in BEVS.

Animals↗
PubMed2005

Overexpression of ERp29 in the thyrocytes of FRTL-5 cells.

It was previously reported that the up-regulation of ERp29 mRNA depends on the levels of thyroid stimulating hormone (TSH) in the thyrocytes of FRTL-5 cells. In order to investigate the putative new function of ERp29 as an endoplasmic molecular (ER) chaperone, an ERp29-overexpressing FRTL-5 cell line was established. This cell line had approximately three times the levels of ERp29 protein and an enhanced level of thyroglobulin (Tg) secretion. The results showed both enhanced ERp29 expression and an interaction with the other ER chaperones such as GRP94, BiP, ERp72 and calnexin. In addition, ERp29 enhanced the expression of PKR-like ER kinase (PERK), which is a transmembrane protein located in the ER membrane. These findings suggest that ERp29 assists in protein folding as well as in the secretion of the secretory/plasma membrane proteins under close co-operation with other ER chaperones and the ER stress signaler, PERK.

Animals↗
PubMed2005

Endoplasmic reticulum stress response of Bombyx mori calreticulin.

We isolated a calreticulin cDNA from the silkworm, Bombyx mori. The cDNA encodes 398 amino acid residues of B. mori calreticulin, with an endoplasmic reticulum retentional HDEL motif at its C-terminus and a predicted molecular mass of 45,801 Da. The B. mori calreticulin shows high protein homology with calreticulin from G. mellonella (88%), A. aegypti (71%), D. melanogaster (69%) and H. sapiens (63%). The highest level of mRNA expression of B. mori calreticulin was exhibited in the fat body of this insect. Although expression of B. mori calreticulin was affected by disturbances in intracellular calcium levels, other ER stress conditions such as inhibition of intracellular protein transport, reduction of disulfide formation, glycosylation inhibition, heat shock and oxidative stress did not disrupt induction of B. mori calreticulin.

Amino Acid Sequence↗
PubMed2005

Brain-derived neurotrophic factor promotes neurite growth and survival of antennal lobe neurons in brain from the silk moth, Bombyx mori in vitro.

This study was conducted to investigate effects of brain-derived neurotrophic factor on the neurite growth and the survival rate of antennal lobe neurons in vitro, and secretion of brain-derived neurotrophic factor-like neuropeptide from brain into hemolymph in the silk moth, Bombyx mori. In primary culture of antennal lobe neurons with brain-derived neurotrophic factor, it promoted both a neurite extension of putative antennal lobe projection neurons and an outgrowth of branches from principal neurites of putative antennal interneurons with significance (p<0.05). Brain-derived neurotrophic factor also increased significantly a survival rate of antennal lobe neurons (p<0.05). Results from immunolabeling of brain and retrocerebral complex, and ELISA assay of hemolymph showed that brain-derived neurotrophic factor-like neuropeptide was synthesized by both median and lateral neurosecretory cells of brain, then transported to corpora allata for storage, and finally secreted into hemolymph for action. These results will provide valuable information for differentiation of invertebrate brain neurons with brain-derived neurotrophic factor.

Animals↗
PubMed2004

ATFC is a novel transducer for the unfolded protein response in Bombyx mori BM5 cells.

We report the isolation of activating transcription factor of chaperone (ATFC), a novel cDNA from Bombyx mori BM5 cells that encodes a putative transducer of endoplasmic reticulum (ER) stress. The 236 amino acids of ATFC include both a basic region and a leucine zipper at the C-terminus, in contrast to Hac1p of yeast which features these structures at its N-terminus. ATFC expression was strongly up-regulated by ER stress. ATFC could specifically bind to the unfolded protein response element. BM5 cells transfected with ATFC cDNA displayed enhanced ER chaperone expression in response to ER stress. These results indicate that ATFC encodes a putative transducer of ER stress.

Amino Acid Sequence↗
PubMed2003

cDNA cloning and mRNA expression of L-3,4-dihydroxyphenylalanine decarboxylase gene homologue from the silkworm, Bombyx mori.

L-3,4-Dihydroxyphenylalanine decarboxylase (DDC) cDNA, from Bombyx mori that contains an open reading frame of 1437 bp encoding 478 amino acids, was cloned and characterized. Expression analyses of B. mori DDC mRNA by Northern and in situ hybridization indicated that expression of silkworm DDC expression is possibly controlled by neuropeptide hormones in tissue- and stage-specific manners.

Amino Acid Sequence↗
PubMed2003

CXC chemokine receptor 4 expression and function in human anaplastic thyroid cancer cells.

Anaplastic thyroid carcinomas (ATCs) are highly aggressive, extremely lethal human cancers with poor therapeutic response. Chemokines are a superfamily of small cytokine-like proteins that induce, through their interaction with G protein-coupled receptors, cytoskeletal rearrangement, firm adhesion to endothelial cells, and directional migration. In this study, we characterized the expression of CXC chemokine receptor 4 (CXCR4) and analyzed its functions in ARO cells, a human ATC cell. The normal primary cultured thyroid cells and ATC cell lines expressed CXCR4 and stromal cell-derived factor (SDF)-1 alpha transcripts, detected by RT-PCR. Fluorescence activated cell sorting analysis of CXCR4 expression in normal and ATC cells showed that ARO cells expressed significant levels of CXCR4. FRO, NPA, and normal thyroid cells did not express membrane CXCR4, as determined by fluorescence activated cell sorting analysis. To identify the functional role of CXCR4 in ARO cells, we treated ARO cells with SDF-1 alpha and analyzed the signaling pathways, cellular migration, and proliferation. SDF-1alpha enhanced the migration but did not affect the proliferation of ARO cells or activate the Janus kinase/signal transducer and activator of transcription signaling pathways. However, SDF-1 alpha/CXCR4 activation resulted in phosphorylation of the p70S6 kinase and its target protein, ribosomal S6 protein, and also activation of the ERK1/ERK2 signaling pathways. Furthermore, SDF-1 alpha/CXCR4- mediated activation of the p70S6 kinase and phosphorylation of the S6 protein were inhibited by treatment with an mTOR/FRAP inhibitor. The specificity of the CXCR4-mediated migration of ARO cells was demonstrated by the dose-dependent inhibition of migration by neutralizing anti-CXCR4. The ATC cells, FRO and NPA, which do not express CXCR4, did not demonstrate significant SDF-1 alpha-mediated migration in vitro. In addition, the CXCR4-mediated migration of ARO cells was inhibited by treatment with pertussis toxin (a Gi-protein inhibitor) and PD 98059 (a mitogen-activated ERK kinase inhibitor) but not by LY294002 and wortmanin, phosphatidylinositol 3-kinase inhibitors. These findings suggest that a subset of ATC cells expresses functional CXCR4, which may be important in tumor cell migration and local tumor invasion.

Carcinoma↗
PubMed2002

Molecular characterization of a Bombyx mori protein disulfide isomerase (bPDI).

We have isolated a complementary deoxyribonucleic acid clone that encodes the protein disulfide isomerase of Bombyx mori (bPDI). This protein has a putative open reading frame of 494 amino acids and a predicted size of 55.6 kDa. In addition, 2 thioredoxin active sites, each with a CGHC sequence, and an endoplasmic reticulum (ER) retention signal site with a KDEL motif were found at the C-terminal. Both sites are typically found in members of the PDI family of proteins. The expression of bPDI messenger ribonucleic acid (mRNA) was markedly increased during ER stress induced by stimulation with calcium ionophore A23187, tunicamycin, and dithiothreitol, all of which are known to cause an accumulation of unfolded proteins in the ER. We also examined the tissue distribution of bPDI mRNA and found pronounced expression in the fat body of insects. Hormonal regulation studies showed that juvenile hormone, insulin, and a combination of juvenile hormone and transferrin (although not transferrin alone) affected bPDI mRNA expression. A challenge with exogenous bacteria also affected expression, and the effect peaked 16 hours after infection. These results suggest that bPDI is a member of the ER-stress protein group, that it may play an important role in exogenous bacterial infection of the fat body, and that its expression is hormone regulated.

Amino Acid Sequence↗
PubMedDate not supplied

Clusterin overexpression is responsible for the anti-apoptosis effect in a mouse neuroblastoma cell line, B103.

The functional role of clusterin in apoptosis was examined using flow cytometry. Clusterin cDNA was transfected into the mouse neuroblastoma cell line, B103, in order to determine if clusterin overexpression inhibits apoptosis. The increased clusterin expression level in the B103 cells tended to suppress the apoptotic index. This suggests an association of clusterin gene expression with apoptosis inhibition. These results support the conclusion that clusterin expression in B103 cells has an anti-apoptotic influence.

Animals↗
PubMedDate not supplied

Expression of the endoplasmic reticulum chaperone GRP94 gene in ischemic gerbil brain.

GRP94 (glucose regulated protein 94) gene expression in the ischemic-hippocampus of gerbils, which was induced by a temporary occlusion of the bilateral common carotid arteries (CCAs), was tested by Northern blot analysis. The maximum GRP94 gene expression level was detected at the occipital lobe 10 min after the induction of ischemia. In the hippocampus, GRP94 gene expression reached a maximum 15 min after inducing ischemia. Following reperfusion, the maximum expression level was shown at 12 h and continuing thereafter.

Animals↗