• Biomolecules & Therapeutics
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• v.26 no.4
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• pp.399-408
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• 2018

In this study, we examined the molecular and functional characterization of choline uptake in the human esophageal cancer cells. In addition, we examined the influence of various drugs on the transport of [$^3H$]choline, and explored the possible correlation between the inhibition of choline uptake and apoptotic cell death. We found that both choline transporter-like protein 1 (CTL1) and CTL2 mRNAs and proteins were highly expressed in esophageal cancer cell lines (KYSE series). CTL1 and CTL2 were located in the plasma membrane and mitochondria, respectively. Choline uptake was saturable and mediated by a single transport system, which is both $Na^+$-independent and pH-dependent. Choline uptake and cell viability were inhibited by various cationic drugs. Furthermore, a correlation analysis of the potencies of 47 drugs for the inhibition of choline uptake and cell viability showed a strong correlation. Choline uptake inhibitors and choline deficiency each inhibited cell viability and increased caspase-3/7 activity. We conclude that extracellular choline is mainly transported via a CTL1. The functional inhibition of CTL1 by cationic drugs could promote apoptotic cell death. Furthermore, CTL2 may be involved in choline uptake in mitochondria, which is the rate-limiting step in S-adenosylmethionine (SAM) synthesis and DNA methylation. Identification of this CTL1- and CTL2-mediated choline transport system provides a potential new target for esophageal cancer therapy.

• Reproductive and Developmental Biology
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• v.31 no.4
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• pp.241-248
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• 2007

Epigenetic modification dependent DNA methyltransferases (DNMTs) play an important role in tissue- and stage-specific gene regulation and normal mammalian development. In this study, we show that DNMTs are expressed at different levels during hematopoietic stem cell (HSC) differentiation to proerythrocytes. DNMT1, DNMT3A, and DNMT3B were highly expressed at day 7 after differentiation. We used specific siRNA as a tool to probe the relationship between the expression of DNMTs and erythropoietic differentiation. When introduced siRNA of DMNT1 and DMNT3b in human $CD34^+$ cells, these more differentiated into erythrocytes. This was confirmed by glycophorin A (GPA) positive cell analysis and globin gene expression. $GPA^+$ cells increased up to $20{\sim}30%$, and ${\gamma}$- and ${\epsilon}$-globin genes increased in siRNA transfected cells. Therefore, our data suggest that suppression of DNA methylation can affect positively differentiation of HSC and may contribute to expression of erythrocyte lineage genes including GPA and globins.

• Environmental Analysis Health and Toxicology
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• v.15 no.3
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• pp.107-113
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• 2000

Chlorophenoxy acids are one of the most useful classes of chlorinated herbicides. Specially 2, 4-D and 2, 4, 5-T were known to endocrine distruptors. In this study, these pesticides in water samples were extracted by liquid-liquid extration at acidic conditions and then derivatization of acidic group was carried out various esterifications using by CH$_3$I/Acetone -K$_2$CO$_3$, H$_2$SO$_4$/MeOH or TFAA/TFE. That result, Sensitivities of TFE derivatized 2, 4-D and 2, 4, 5-T are prior to the others. The recoveries of 2, 4-D and 2, 4, 5-T were 98% and 82% respectively using diethyl ether as an extracting solvent.

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.572-578
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• 2016

Communication between endothelial cells (ECs) and smooth muscle cells (SMCs) via miR-143/145 clusters is vital to vascular stability. Previous research demonstrates that miR-143/145 released from ECs can regulate SMC proliferation and migration. In addition, a recent study has found that SMCs also have the capability of manipulating EC function via miR-143/145. In the present study, we artificially increased the expression of miR-143/145 in ECs, to mimic a similar change caused by miR-143/145 released by SMCs, and applied untargeted metabolomics analysis, aimed at investigating the consequential effect of miR-143/145 overexpression. Our results showed that miR-143/145 overexpression alters the levels of metabolites involved in energy production, DNA methylation, and oxidative stress. These changed metabolites indicate that metabolic pathways, such as the SAM cycle and TCA cycle, exhibit significant differences from the norm with miR-143/145 overexpression.

• Molecular & Cellular Toxicology
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• v.1 no.2
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• pp.73-77
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• 2005

Nickel is the one of potent environmental, the occupational pollutants and the classified human carcinogens. It is a serious hazard to human health, when the metal exposure. To prevent human diseases from the heavy metals, it is seemingly important that understanding of how nickel exerts their toxicity and carcinogenic effect at a molecular and a genomic level. The process of nickel absorption has been demonstrated as phagocytosis, iron channel and diffusion. Uptaked nickel has been suggested to induce carcinogenesis via two pathways, a direct DNA damaging pathway and an indirect DNA damaging pathway. The former was originated from the ability of metal to generate Reactive Oxygen Species (ROS) and the reactive intermediates to interact with DNA directly. Ni-generated ROS or Nickel itself, interacts with DNAs and histones to cause DNA damage and chromosomal abnormality. The latter was originated from an indirect DNA damage via inhibition of DNA repair, or condensation and methylation of DNA. Cells have ability to protect from the genotoxic stresses by changing gene expression. Microarray analysis of the cells treated with nickel or nickel compounds, show the specific altered gene expression profile. For example, HIF-I (Hypoxia-Inducible Factor I) and p53 were well known as transcription factors, which are upregulated in response to stress and activated by both soluble and insoluble nickel compounds. The induction of these important transcription factors exert potent selective pressure and leading to cell transformation. Genes of metallothionein and family of heat shock proteins which have been known to play role in protection and damage control, were also induced by nickel treatment. These gene expressions may give us a clue to understand of the carcinogenesis mechanism of nickel. Further discussions on molecular and genomic, are need in order to understand the specific mechanism of nickel toxicity and carcinogenicity.

• Molecules and Cells
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• v.39 no.8
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• pp.631-638
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• 2016

Glutathione peroxidase 3 (GPx3), an antioxidant enzyme, acts as a modulator of redox signaling, has immunomodulatory function, and catalyzes the detoxification of reactive oxygen species (ROS). GPx3 has been identified as a tumor suppressor in many cancers. Although hyper-methylation of the GPx3 promoter has been shown to down-regulate its expression, other mechanisms by which GPx3 expression is regulated have not been reported. The aim of this study was to further elucidate the mechanisms of GPx3 regulation. GPx3 gene analysis predicted the presence of ten glucocorticoid response elements (GREs) on the GPx3 gene. This result prompted us to investigate whether GPx3 expression is regulated by the glucocorticoid receptor (GR), which is implicated in tumor response to chemotherapy. The corticosteroid dexamethasone (Dex) was used to examine the possible relationship between GR and GPx3 expression. Dex significantly induced GPx3 expression in H1299, H1650, and H1975 cell lines, which exhibit low levels of GPx3 expression under normal conditions. The results of EMSA and ChIP-PCR suggest that GR binds directly to GRE 6 and 7, both of which are located near the GPx3 promoter. Assessment of GPx3 transcription efficiency using a luciferase reporter system showed that blocking formation of the GR-GRE complexes reduced luciferase activity by 7-8-fold. Suppression of GR expression by siRNA transfection also induced down-regulation of GPx3. These data indicate that GPx3 expression can be regulated independently via epigenetic or GR-mediated mechanisms in lung cancer cells, and suggest that GPx3 could potentiate glucocorticoid (GC)-mediated anti-infla-mmatory signaling in lung cancer cells.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.69-72
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• 2004

Somaclonal variation, defined as phenotypic and genetic variations among regenerated plants from a parental plant, could be caused by changes in chromosome structure, single gene mutation, cytoplasm genetic mutation, insertion of transposable elements, and DNA methylation during plant regeneration. The objective of this study was to evaluate DNA variations among somaclonal variants from the cotyledonary node culture in soybean. A total of 61 soybean somaclones including seven $\textrm{R}_1$ lines and seven $\textrm{R}_2$ lines from Iksannamulkong as well as 27 $\textrm{R}_1$ lines and 20 $\textrm{R}_2$ lines from Jinju 1 were regenerated by organogenesis from the soybean cotyledonary node culture system. Field evaluation revealed no phenotypic difference in major agronomic traits between somaclonal variants and their wild types. AFLP and SSR analyses were performed to detect variations at the DNA level among somaclonal variants of two varieties. Based on AFLP analysis using 36 primer sets, 17 of 892 bands were polymorphic between Iksannamulkong and its somaclonal variants and 11 of 887 bands were polymorphic between Jinju 1 and its somaclonal variants, indicating the presence of DNA sequence change during plant regeneration. Using 36 SSR markers, two polymorphic SSR markers were detected between Iksannamulkong and its somaclonal variants. Sequence comparison amplified with the primers flanking Satt545 showed four additional stretches of ATT repeat in the variant. This suggests that variation at the DNA level between somaclonal variants and their wild types could provide basis for inducing mutation via plant regeneration and broadening crop genetic diversity.

• Toxicological Research
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• v.24 no.3
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• pp.219-225
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• 2008

A screening study of the acute toxicity of organic arsenics such as arsenobetaine and arsenocholine, a product of arsenic methylation metabolite, and inorganic arsenic was carried out to examine hematological and serum biochemical parameters in cynomolgus monkeys(Macaca fascicularis). We found soft and liquid feces, and vomiting in all treated groups with inorganic and organic arsenics. The monkeys in inorganic arsenic-treated group showed a significant increase in vomiting frequency compared with those in three organic arsenics-treated groups. These results suggest that inorganic arsenic might be more toxic than three other organic arsenics tested. The monkeys in inorganic arsenic-treated group showed a decrease in platelet and an increase in monocyte on day 4 and the monkeys in arsenocholine-treated group showed an increase in reticulocyte percentage on day 8. The monkeys in inorganic-treated group also showed decreases in AST and ALT values and the monkeys in arsenobetaine-treated group showed a decrease in AST value and an increase in T-CHO value. However, these hematological and biochemical changes were within the physiological ranges, showing that the single dose of inorganic and organic arsenics did not affect at least hematological and serum biochemical parameters. The present study of toxicity with single dose of arsenics provides valuable indicators for longer term study of toxicity of repeated doses of arsenics in primates.

• Biomedical Science Letters
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• v.13 no.3
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• pp.239-244
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• 2007

Hoxc8 is one of the homeotic developmental control genes regulating the expression of many downstream target genes, through which animal body pattern is established during embryonic development. In previous proteomics analysis, proliferating cell nuclear antigen (PCNA) which is also known as cyclin, has been implied to be regulated by Hoxc8 in F9 murine embryonic teratocarcinoma cell. When the 5' upstream region of PCNA was analyzed, it turned out to contain 20 Hox core binding sites (ATTA) in about 1.17 kbp (kilo base pairs) region ($-520{\sim}-1690$). In order to test whether this region is responsible for Hoxc8 regulation, the upstream 2.3 kbp fragment of PCNA was amplified through PCR and then cloned into the pGL3 basic vector containing a luciferase gene as a reporter. When the luciferase activity was measured in the presence of effector plasmid (pcDNA : c8) expressing murine Hoxc8, the PCNA promoter driven reporter activity was reduced. To confirm whether this reduction is due to the Hoxc8 protein, the siRNA against Hoxc8 (5'-GUA UCA GAC CUU GGA ACU A-3' and 5'-UAG UUC CAA GGU CUG AUA C-3') was prepared. Interestingly enough, siRNA treatment up regulated the luciferase activity which was down regulated by Hoxc8, indicating that Hoxc8 indeed regulates the expression of PCNA, in particular, down regulation in NIN3T3 cells. These results altogether indicate that Hoxc8 might orchestrate the pattern formation by regulating PCNA which is one of the important proteins involved in several processes such as DNA replication and methylation, chromatin remodeling, cell cycle regulation, differentiation, as well as programmed cell death.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.324-328
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• 1992

The $^1H$ NMR chemical shifts and coupling constants for ${\alpha}$-, permethyl-${\alpha}$-, ${\beta}$-and permethyl-${\beta}$-cyclodextrins in neutral aqueous media were assigned based on the 470MHz spectra. In order to obtain accurate chemical shifts and coupling constants the experimental spectra were analyzed with the Raccoon spin simulation program. The rotamer distribution around the$C_{5-}C_6$ bond of the cyclodextrins evaluated from the coupling constants of $J_{56a}$ and $J_{56b}$. In our calculation of the ${\alpha}$-, and ${\beta}$-cycliodextrin showed that gg conformers were most favorable form and tg conformers were least favorable form. It is very interesting to note the changes in $J_{56a}$, $J_{56b}$ coupling constants of permethylated ${\alpha}$- and ${\beta}$-cyclodextrins from unmodified one. The gg conformers were more increased than unmodified one and instead of tg conformers gt conformers were least favorable one upon methylation.