• The Plant Pathology Journal
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• v.24 no.3
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• pp.296-304
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• 2008

The transient and rapid expression system of a foreign protein in planta is a very useful technique in biotechnology application. We have investigated optimum condition of Agrobacterium-infiltration technique in which expression level of foreign proteins were maximized without detrimental effects on plants using GFP and Cucumber mosaic virus 2b protein, which is known as an enhancer of gene expression and a suppressor of post-transcriptional gene silencing(PTGS). The optimum expression level of both RNA and protein of GFP with minimum leaf impairment was obtained at $OD_{600}$=0.2 of Agrobactrium inocula. The steady-state levels of GFP RNA and protein generally peaked at 3 and 7 days post-infiltration(dpi), respectively. In the presence of 2b, both the magnitude and duration of GFP expression was highly increased and we could detect GFP level until 17 dpi. On the other hands, the 2b-mediated higher accumulation of foreign proteins resulted in the repression of normal leaf growth, possibly due to the limitation of supply of energy or materials required for growth maintenance. Using this Agrobacterium-infiltration system with 2b and GFP, we tested a hypothesis for the threshold model of PTGS initiation. Four GFP transgenic lines of N. benthamiana, which shows different expression level of GFP were tested to determine the threshold level for PTGS initiation. Agrobacterium-infiltration of GFP into those GFP-transgenic plants resulted in the co-silencing of the transgenic GFP. It was found that very low concentration of Agrobacterium with GFP and GFP+2b($OD_{600}$=0.002-0.02) which could not phenotypically induce an additive GFP expression, was enough to trigger PTGS pathway in all GFP transgenic plants. This strongly indicates that each GFP-transgenic plant should be expressing the transgenic GFP at its own pre-determined level and there was no buffer zone of additive GFP-expression to the threshold. In other words, the PTGS seems to be immediately activated as a self-defensive mechanism if an internal balance of gene expression is broken.

• Journal of Life Science
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• v.26 no.1
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• pp.140-145
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• 2016

Genes in multicellular organisms are transcribed in development, differentiation, or tissue-specific manners. The transcription of genes is activated by enhancers, which are transcription regulatory elements located at long distances from the genes. Recent studies have reported that noncoding RNAs are transcribed from active enhancers by RNA polymerase II (RNA Pol II); these are called enhancer RNAs (eRNAs). eRNAs are transcribed bi-directionally from the enhancer core, and are capped on the 5’ end but not spliced or polyadenylated on the 3’ end. The transcription of eRNAs requires the binding of transcription activators on the enhancer and associates positively with the transcription of the target gene. The transcriptional inhibition of eRNAs or the removal of eRNA transcripts results in the transcriptional repression of the coding gene. The transcriptional procedure of eRNAs causes enhancer- specific histone modifications, such as histone H3K4me1/2. eRNA transcripts directly interact with Mediator and Rad21, a cohesin subunit, generating a chromatin loop structure between the enhancer and the promoter of the target gene. The recruitment of RNA Pol II into the promoter and its elongation through the coding region are facilitated by eRNAs. Here, we will review the features of eRNAs, and discuss the mechanism of eRNA transcription and the roles of eRNAs in the transcriptional activation of target genes.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.9
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• pp.3723-3727
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• 2015

The p53 tumor suppressor protein is a principal mediator of growth arrest, senescence, and apoptosis in response to a broad array of cellular damage. p53 is a substrate for the ubiquitin-proteasome system, however, the ubiquitin-conjugating enzymes (E2s) involved in p53 ubiquitination have not been well studied. UBE2Q1 is a novel E2 ubiquitin conjugating enzyme gene. Here, we investigated the effect of UBE2Q1 overexpression on the level of p53 in the MDA-MB-468 breast cancer cell line as well as the interaction between UBE2Q1 and p53. By using a lipofection method, the p53 mutated breast cancer cell line, MDA-MB-468, was transfected with the vector pCMV6-AN-GFP, containing UBE2Q1 ORF. Western blot analysis was employed to verify the overexpression of UBE2Q1 in MDA-MB-468 cells and to evaluate the expression level of p53 before and after cell transfection. Immunoprecipitation and GST pull-down protocols were used to investigate the binding of UBE2Q1 to p53. We established MDA-MB-468 cells that transiently expressed a GFP fusion proteins containing UBE2Q1 (GFP-UBE2Q1). Western blot analysis revealed that levels of p53 were markedly lower in UBE2Q1 transfected MDA-MB-468 cells as compared with control MDA-MB-468 cells. Both in vivo and in vitro data showed that UBE2Q1 co-precipitated with p53 protein. Our data for the first time showed that overexpression of UBE2Q1can lead to the repression of p53 in MDA-MB-468 cells. This repression of p53 may be due to its UBE2Q1 mediated ubiquitination and subsequent proteasome degradation, a process that may involve direct interaction of UBE2Q1with p53.

• Development and Reproduction
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• v.15 no.4
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• pp.273-279
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• 2011

Epigenetic regulation is a phenomenon that changes the gene function without changing the underlying DNA sequences. Epigenetic status of chromosome is regulated by mechanisms such as histone modification, DNA modification, and RNAi silencing. In this review, we focused on histone methylation for epigenetic regulation in ES cells. Two antagonizing multiprotein complexes regulate methylation of histones to guide expression of genes in ES cells. The Polycomb repressive complex 2 (PRC2), including EED, EZH2, and SUZ12 as core factors, contributes to gene repression by increasing trimethylation of H3K27 (H3K27me3). In contrast, the Trithorax group (TrxG) complex including MLL is related to gene activation by making H3K4me3. PRC2 and TrxG accompany a variety of accessory proteins. Most prominent feature of epigenetic regulation in ES cells is a bivalent state in which H3K27me3 and H3K4me3 appear simultaneously. Concerted regulation of PRC2, TrxG complex, and H3K4- or H3K27-specific demethylases activate expression of pluripotency-related genes and suppress development-related genes in ES cells. Modified balance of the regulators also enables ES cells to efficiently differentiate to a variety of cells upon differentiating signals. More detailed insights on the epigenetic regulators and their action will lead us to better understanding and use of ES cells for future application.

• BMB Reports
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• v.44 no.1
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• pp.58-63
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• 2011

Zinc finger (ZNF) proteins play a critical role in cell growth, proliferation, apoptosis, and intracellular signal transduction. In this paper, we cloned and characterized a novel human KRAB-related zinc finger gene, ZNF425, which encodes a protein of 752 amino acids. ZNF425 is strongly expressed in the three month old human embryos and then is almost undetectable in six month old embryos and in adult tissues. An EGFP-ZNF425 fusion protein can be found in both the nucleus and the cytoplasm. ZNF425 appears to act as a transcription repressor. Over-expression of ZNF425 inhibits the transcriptional activities of SRE, AP-1, and SRF. Deletion analysis indicates that the C2H2 domain is the main region responsible for the repression. Our results suggest that the ZNF425 gene is a new transcriptional inhibitor that functions in the MAPK signaling pathway.

• Journal of Life Science
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• v.20 no.5
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• pp.655-661
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• 2010

To elucidate the mechanism underlying the suppressive regulation of hST8Sia I expression in retinoic acid (RA)-induced SK-MEL-2 cells, we characterized the promoter region of the hST8Sia I gene. Functional analysis of the 5‘-flanking region of the hST8Sia I gene by the transient expression method showed that the -1146 to -646 region, which contains putative binding sites for transcription factors c-Ets-1, CREB, AP-1 and NF-kB, functions as the RA-repressive promoter in SK-MEL-2 cells. Site-directed mutagenesis and ChIP analyses indicated that the NF-kB binding site at -731 to -722 is crucial for the RA-induced repression of hST8Sia I in SK-MEL-2 cells. In addition, the transcriptional activity of hST8Sia I suppressed by RA in SK-MEL-2 cells was strongly inhibited by extracellular signal-regulated protein kinase (ERK) inhibitor U0126 and protein kinase C (PKC) inhibitor GO6976, as determined by RT-PCR and luciferase assay of hST8Sia I promoter containing the -1146 to -646 regions. These results suggest that RA markedly modulates transcriptional regulation of hST8Sia I gene expression through the PKC/ERK signal pathway in SK-MEL-2 cells.

• Journal of Ginseng Research
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• v.37 no.3
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• pp.315-323
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• 2013

Ginseng is known to have antistress effects. Previously, red ginseng (RG) was shown to repress stress-induced peptidyl arginine deiminase type IV (PADI4) via estrogen receptor ${\beta}$ ($ER{\beta}$) in the brain, thus inhibiting brain cell apoptosis. Moreover, tumor necrosis factor (TNF)-${\alpha}$ plays a critical role in immobilization (IMO) stress. However, the signaling pathway of RG-mediated repressesion of inflammation is not completely understood. In this study, we determined how RG modulated gene expression in stressed brain cells. Since secretion of TNF-${\alpha}$ is modulated via TNF-${\alpha}$ converting enzyme (TACE) and nuclear factor (NF)-${\kappa}B$, we examined the inflammatory pathway in stressed brain cells. Immunohistochemistry revealed that TACE was induced by IMO stress, but RG repressed TACE induction. Moreover, PADI4 siRNA repressed TACE expression compared to the mock transfected control suggesting that PADI4 was required for TACE expression. A reporter assay also revealed that $H_2O_2$ oxidative stress induced NF-${\kappa}B$ in neuroblastoma SK-N-SH cells, however, RG pretreatment repressed NF-${\kappa}B$ induction. These findings were supported by significant induction of nitric oxide and reactive oxygen species (ROS) by oxidative stress, which could be repressed by RG administration. Taken together, RG appeared to repress stress-induced PADI4 via TACE and NF-${\kappa}B$ in brain cells thus preventing production of ROS and subsequently protecting brain cells from apoptosis.

• BMB Reports
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• v.44 no.8
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• pp.547-552
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• 2011

MED19 is a member of the Mediator that plays a key role in the activation and repression of signal transduction or the regulation of transcription in carcinomas. To tested the functional role of MED19 in human prostate cancer, we downregulated MED19 expression in prostate cancer cells (PC-3 and DU145) by lentivirus-mediated short hairpin (shRNA), and analyzed the effect of inhibition of MED19 on prostate cancer cell proliferation and tumorigenesis. The in vitro prostate cancer cell proliferation, colony formation, and in vivo tumor growth in nude mice xenografts was significantly reduced after the downregulation of MED19. Knockdown of MED19 caused S-phase arrest and induced apoptosis via modulation of Bid and Caspase 7. It was suggested that MED19 serves as a novel proliferation regulator that promotes growth of prostate cancer cells.

• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.243-249
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• 2017

An agar-degrading bacterium, designated as the GNUM08123 strain, was isolated from samples of red algae collected from the Yongil Bay near East Sea, Korea. The isolated GNUM08123 strain was gram-negative, aerobic, motile, and beige-pigmented, with $C_{16:0}$ (25.9%) and summed feature 3 (comprising $C_{16:1}{\omega}7c/iso-C_{15:0}2-OH$, 34.4%) as its major cellular fatty acids. A similarity search based on the 16S rRNA gene sequence revealed that it belonged to class Gammaproteobacteria and shared 97.7% similarity with the type strain Vibrio chagasii $R-3712^T$. The DNA G+C content of strain $GNUM08123^T$ was 46.9 mol%. The major isoprenoid quinone was ubiquinone-8. The results of DNA-DNA relatedness and 16S rRNA sequence similarity analyses, in addition to its phenotypic and chemotaxonomic characteristics, suggest that strain GNUM08123 is a novel species within genus Vibrio, designated as Vibrio sp. GNUM08123. Agarase production by strain GNUM08123 was induced by agar and sucrose, but was repressed probably owing to carbon catabolite repression by glucose and maltose.

• BMB Reports
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• v.49 no.8
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• pp.401-402
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• 2016

S6K1 is a key regulator of cell growth, cell size, and metabolism. Although the role of cytosolic S6K1 in cellular processes is well established, the function of S6K1 in the nucleus remains poorly understood. Our recent study has revealed that S6K1 is translocated into the nucleus upon adipogenic stimulus where it directly binds to and phosphorylates H2B at serine 36. Such phosphorylation promotes EZH2 recruitment and subsequent histone H3K27 trimethylation on the promoter of its target genes including Wnt6, Wnt10a, and Wnt10b, leading to repression of their expression. S6K1-mediated suppression of Wnt genes facilitates adipogenic differentiation through the expression of adipogenic transcription factors PPARγ and Cebpa. White adipose tissues from S6K1-deficient mice consistently exhibit marked reduction in H2BS36 phosphorylation (H2BS36p) and H3K27 trimethylation (H3K27me3), leading to enhanced expression of Wnt genes. In addition, expression levels of H2BS36p and H3K27me3 are highly elevated in white adipose tissues from mice fed on high-fat diet or from obese humans. These findings describe a novel role of S6K1 as a transcriptional regulator controlling an epigenetic network initiated by phosphorylation of H2B and trimethylation of H3, thus shutting off Wnt gene expression in early adipogenesis.