• Molecules and Cells
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• v.38 no.6
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• pp.573-579
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• 2015

Apolipoprotein A-I and A-IV are protein constituents of high-density lipoproteins although their functional difference in lipoprotein metabolism is still unclear. To compare anti-atherogenic properties between apoA-I and apoA-4, we characterized both proteins in lipid-free and lipidbound state. In lipid-free state, apoA4 showed two distinct bands, around 78 and $67{\AA}$ on native gel electrophoresis, while apoA-I showed scattered band pattern less than $71{\AA}$. In reconstituted HDL (rHDL) state, apoA-4 showed three major bands around $101{\AA}$ and $113{\AA}$, while apoA-I-rHDL showed almost single band around $98{\AA}$ size. Lipid-free apoA-I showed 2.9-fold higher phospholipid binding ability than apoA-4. In lipid-free state, $BS_3$-crosslinking revealed that apoA-4 showed less multimerization tendency upto dimer, while apoA-I showed pentamerization. In rHDL state (95:1), apoA-4 was existed as dimer as like as apoA-I. With higher phospholipid content (255:1), five apoA-I and three apoA-4 were required to the bigger rHDL formation. Regardless of particle size, apoA-I-rHDL showed superior LCAT activation ability than apoA-4-rHDL. Uptake of acetylated LDL was inhibited by apoA-I in both lipid-free and lipid-bound state, while apoA-4 inhibited it only lipid-free state. ApoA-4 showed less anti-atherogenic activity with more sensitivity to glycation. In conclusion, apoA-4 showed inferior physiological functions in lipid-bound state, compared with those of apoA-I, to induce more pro-atherosclerotic properties.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.105-109
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• 2009

Among signal transduction systems by protein phosphorylation Akt/PKB protein kinase which is one of serine/threonine kinases, is known to regulate the survival and death of the cell and glucose metabolism. Thus, Akt/PKB protein kinase has been used as one of the target proteins to find anti-cancer agents from natural products. In this study, human Akt/PKB protein kinase was expressed in Escherichia coli expression system for the mass production. Human Akt/PKB protein kinase expressed in E. coli formed inclusion body under the general condition. However, most of the expressed protein was solubilized under the culture temperature at $27^{\circ}C$ and 0.01-0.09 mM of IPTG for induction of the protein expression. The expressed protein was purified using $Ni^{2+}$-NTA agarose column and confirmed by using anti-Akt antibody. Subsequently, the purified human Akt/PKB protein kinase was activated by in vitro phosphorylation using cellular extract containing kinases. The activated protein was confirmed to phosphorylate the specific fluorescent peptide specially designed as the artificial substrate for Akt/PKB protein kinase.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.97-97
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• 2003

Embryonic stem (ES) cells, derived from preimplantation embryos, are able to differentiate into various types of cells consisting the whole body, or pluripotency. In addition to the plasticity, ES cells are expected to be different from terminally differentiated cells in very many ways, such as patterns of gene expressions, ability and response of the cells in confronting environmental stimulations, metabolism, and growth rate. As a model system to differentiate these two types of cells, human ES (hES, MB03) cells and terminally differentiated cells (HeLa), we examined the ability of these two types of cells in confronting a severe oxidative insult, that is $H_2 O_2$. Ratio of dying cells as determined by the relative amount of dye neutral red entrapped within the cells after the exposures. Cell death rates were not significantly different when either MB03 or HeLa were exposed up to 0.4 mM $H_2 O_2$. However, relative amount of dye entrapped within the cells sharply decreased down to 0.12% in HeLa cells when the cells were exposed to 0.8 mM $H_2 O_2$, while it was approximately 54% in MB03. Pretreatment of cells with BSO (GSH chelator) and measurement of GSH content results suggest that cellular GSH is the major defensive mechanism of hES cells. Induction of apoptosis in hES cell was confirmed by DNA laddering, induction of Bax, and chromatin condensation. In summary, hES cells 1) are extremely resistant to oxidative stress, 2) utilize GSH as a major defensive mechanism. and 3) experience apoptosis upon exposure to oxidative stress.

• Genomics & Informatics
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• v.10 no.1
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• pp.16-22
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• 2012

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by formation of multiple fluid-filled cysts that expand over time and destroy renal architecture. The proteins encoded by the $PKD1$ and $PKD2$ genes, mutations in which account for nearly all cases of ADPKD, may help guard against cystogenesis. Previously developed mouse models of $PKD1$ and $PKD2$ demonstrated an embryonic lethal phenotype and massive cyst formation in the kidney, indicating that $PKD1$ and $PKD2$ probably play important roles during normal renal tubular development. However, their precise role in development and the cellular mechanisms of cyst formation induced by $PKD1$ and $PKD2$ mutations are not fully understood. To address this question, we presently created $Pkd2$ knockout and $PKD2$ transgenic mouse embryo fibroblasts. We used a mouse oligonucleotide microarray to identify messenger RNAs whose expression was altered by the overexpression of the $PKD2$ or knockout of the $Pkd2$. The majority of identified mutations was involved in critical biological processes, such as metabolism, transcription, cell adhesion, cell cycle, and signal transduction. Herein, we confirmed differential expressions of several genes including aquaporin-1, according to different $PKD2$ expression levels in ADPKD mouse models, through microarray analysis. These data may be helpful in $PKD2$-related mechanisms of ADPKD pathogenesis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.5
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• pp.661-670
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• 2006

Selenium (Se) obtained from dietary sources including cereals, grains and vegetables is an essential micronutrient for normal function of the body. Plants convert Se into selenomethionine and incorporate it into proteins in place of methionine, while higher animals synthesize selenoproteins containing selenocysteine. Excessive Se in the body is methylated stepwise to methylated selenium metabolites from selenide. Both inorganic and organic forms of selenium can be the nutritional sources in human, and they are transformed to selenide and then the amino acid selenocysteine attached to a specific $tRNA^{ser(sec)}$. The selenocysteine (Sec) is incorporated into selenoprotein sequences by the UGA codon. The decoding of UGA as Sec requires specific mechanisms because UGA is normally read as a stop codon: cis-acting sequences in the mRNA (the selenocysteine insertion sequence, SECIS, within the 3'untranslated region) and trans -acting factors dedicated to Sec incorporation are required for incorporation of Sec during translation of selenoprotein mRNAs. Approximately 25 selenoproteins have been identified in mammals. Several of these, including glutathione peroxidases, thioredoxin reductases and selenoprotein P, have been purified or cloned, allowing further characterization of their biological function. The antioxidant properties of selenoproteins help prevent cellular damage from free radicals which may contribute to the development of chronic disease such as cancer and heart disease. Other selenoproteins have important roles in regulation of thyroid function and play a role in the immune system. Daily selenium iatake was reported to be $42.0{\pm}16.9{\mu}g/day$ in Korean adult women. This review focuses on the metabolism and biological functions of selenium, and the nutritional status of selenium in the Korean population.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.3
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• pp.579-586
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• 2018

With the beginning of the new era of bigdata, information extraction or prediction are an important research area. Here, we present the acquisition of semi-automatically curated large-scale biological database and the prediction of enzyme reaction annotation for analyzing the pharmacological activities of drugs. Because the xenobiotic metabolism of pharmaceutical drugs by cellular enzymes is an important aspect of pharmacology and medicine. In this study, we apply and analyze similarity models to predict bimolecular reactions between human enzymes and their corresponding substrates. Thirteen models select to reflect the characteristics of each cluster in the similarity model. These models compare based on sensitivity and AUC. Among the evaluation models, the Simpson coefficient model showed the best performance in predicting the reactivity between the enzymes. The whole similarity model implement as a web service. The proposed model can respond dynamically to the addition of reaction information, which will contribute to the shortening of new drug development time and cost reduction.

• Molecules and Cells
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• v.27 no.6
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• pp.651-656
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• 2009

The formation of ${\beta}$-amyloid peptide ($A{\beta}$) is initiated from cleavage of amyloid precursor protein (APP) by a family of protease, ${\alpha}$-, ${\beta}$-, and ${\gamma}$-secretase. Sub W, a substrate peptide, consists of 10 amino acids, which are adjacent to the ${\beta}$-cleavage site of wild-type APP, and Sub M is Swedish mutant with double mutations on the left side of the ${\beta}$-cleavage site of APP. Sub W is a normal product of the metabolism of APP in the secretary pathway. Sub M is known to increase the efficiency of ${\beta}$-secretase activity, resulting in a more specific binding model compared to Sub W. Three-dimensional structures of Sub W and Sub M were studied by CD and NMR spectroscopy in water solution. On the basis of these structures, interaction models of ${\beta}$-secretase and substrate peptides were determined by molecular dynamics simulation. Four hydrogen bonds and one water-mediated interaction were formed in the docking models. In particular, the hydrogen bonding network of Sub M-BACE formed spread over the broad region of the active site of ${\beta}$-secretase (P5-P3'), and the side chain of P2- Asn formed a hydrogen bond specifically with the side chain of Arg235. These are more favorable to the cleavage of Sub M by ${\beta}$-secretase than Sub W. The two substrate peptides showed different tendency to bind to ${\beta}$-secretase and this information may useful for drug development to treat and prevent Alzheimer's disease.

• Molecules and Cells
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• v.27 no.1
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• pp.67-74
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• 2009

Autophagy degrades toxic materials and old organelles, and recycles nutrients in eukaryotic cells. Whereas the studies on autophagy have been reported in other eukaryotic cells, its functioning in plants has not been well elucidated. We analyzed the roles of OsATG10 genes, which are autophagy-related. Two rice ATG10 genes - OsATG10a and OsATG10b - share significant sequence homology (about 75%), and were ubiquitously expressed in all organs examined here. GUS assay indicated that OsATG10b was highly expressed in the mesophyll cells and vascular tissue of younger leaves, but its level of expression decreased in older leaves. We identified T-DNA insertional mutants in that gene. Those osatg10b mutants were sensitive to treatments with high salt and methyl viologen (MV). Monodansylcadaverine-staining experiments showed that the number of autophagosomes was significantly decreased in the mutants compared with the WT. Furthermore, the amount of oxidized proteins increased in MV-treated mutant seedlings. These results demonstrate that OsATG10b plays an important role in the survival of rice cells against oxidative stresses.

• Biomolecules & Therapeutics
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• v.18 no.3
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• pp.343-349
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• 2010

This study was designed to investigate the effects of ticlopidine on the pharmacokinetics of carvedilol after oral or intravenous administration of carvedilol in rats. Carvedilol was administered orally (3 mg/kg) or intravenously (1 mg/kg) without or with oral administration of ticlopidine (4, 12 mg/kg) to rats. The effects of ticlopidine on P-glycoprotein (P-gp) and cytochrome P450 (CYP) 2C9 activity were also evaluated. Ticlopidine inhibited CYP2C9 activity in a concentration-dependent manner with 50% inhibition concentration ($IC_{50}$) of $25.2\;{\mu}M$. In addition, ticlopidine could not significantly enhance the cellular accumulation of rhodamine 123 in MCF-7/ADR cells overexpressing P-gp. Compared with the control group (given carvedilol alone), the area under the plasma concentration-time curve (AUC) was significantly (12 mg/kg, p<0.05) increased by 14-41%, and the peak concentration ($C_{max}$) was significantly (12 mg/kg, p<0.05) increased by 10.7-73.3% in the presence of ticlopidine after oral administration of carvedilol. Consequently, the relative bioavailability (R.B.) of carvedilol was increased by 1.14- to 1.41-fold and the absolute bioavailability (A.B.) of carvedilol in the presence of ticlopidine was increased by 36.2-38.5%. Compared to the i.v. control, ticlopidine could not significantly change the pharmacokinetic parameters of i.v. administered carvedilol. The enhanced oral bioavailability of carvedilol may result from inhibition of CYP2C9-mediated metabolism rather than P-gpmediated efflux of carvedilol in the intestinal and/or in liver and renal eliminatin of carvedilol by ticlopidine.

• Molecular & Cellular Toxicology
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• v.4 no.2
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• pp.124-131
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• 2008

The growing problem of obesity is associated with numerous medical conditions. Several studies have reported that activation of thyroid hormone receptor beta $(THR{\beta})$ is involved in lipid metabolism and thermogenesis. To identify the relationship between the $THR{\beta}$ gene and obesity, we genotyped eighty two single nucleotide polymorphisms (SNPs) in the gene using the Affymetrix array chip in 209 overweight/obese and 155 normal subjects in Korean population. Of the eighty two polymorphisms, the seven SNPs exhibited a significant association with overweight/obesity in three alternative models (codominant, dominant, and recessive models; P<0.05 after adjusting for age and sex) were rs826221 (+267878 T>C), rs4858604 (+186399 A>G), rs1158265 (+200152 T>C), rs1868575 (+206031 G>A), rs1700939 (+238467 T>A), rs1505301 (+241933 T>C), and rs1924768 (+126491 T>C). During haplotype analysis using HapAnalyzer software, 2 haplotypes (block 13: TTAT; block 15: CTGC) containing significant polymorphisms (rs1700939 +238467 T>A and rs4858604 +186399 A>G) were detected to be significantly different. The results suggest that the $THR{\beta}$ gene may be associated with overweight/obesity in Korean population.