• BMB Reports
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• v.52 no.2
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• pp.111-112
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• 2019

Although many studies have reported that the breakdown of the blood-brain barrier (BBB) represents one of the major pathological changes in aging, the mechanism underlying this process remains relatively unexplored. In this study, we described that acid sphingomyelinase (ASM) derived from endothelial cells plays a critical role in BBB disruption in aging. ASM levels were elevated in the brain endothelium and plasma of aged humans and mice, resulting in BBB leakage through an increase in caveolae-mediated transcytosis. Moreover, ASM caused damage to the caveolae-cytoskeleton via protein phosphatase 1-mediated ezrin/radixin/moesin dephosphorylation in primary mouse brain endothelial cells. Mice overexpressing brain endothelial cell-specific ASM exhibited acceleration of BBB impairment and neuronal dysfunction. However, genetic inhibition and endothelial specific knock-down of ASM in mice improved BBB disruption and neurocognitive impairment during aging. Results of this study revealed a novel role of ASM in the regulation of BBB integrity and neuronal function in aging, thus highlighting the potential of ASM as a new therapeutic target for anti-aging.

• Communications for Statistical Applications and Methods
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• v.28 no.3
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• pp.251-265
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• 2021

This paper discusses the pricing of autocallable structured product with knock-in (KI) feature using the exit probability with the Brownian Bridge technique. The explicit pricing formula of autocallable ELS derived in the existing paper handles the part including the minimum of the Brownian motion using the inclusion-exclusion principle. This has the disadvantage that the pricing formula is complicate because of the probability with minimum value and the computational volume increases dramatically as the number of autocall chances increases. To solve this problem, we applied an efficient and robust simulation method called the Brownian Bridge technique, which provides the probability of touching the predetermined barrier when the initial and terminal values of the process following the Brownian motion in a certain interval are specified. We rewrite the existing pricing formula and provide a brief theoretical background and computational algorithm for the technique. We also provide several numerical examples computed in three different ways: explicit pricing formula, the Crude Monte Carlo simulation method and the Brownian Bridge technique.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2783-2791
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• 2022

Molecular dynamics simulations were performed to predict the behavior of graphite atoms under neutron irradiation using large-scale atomic/molecular massively parallel simulator (LAMMPS) package with adaptive intermolecular reactive empirical bond order (AIREBOM) potential. Defect structures of graphite were compared with results from previous studies by means of density functional theory (DFT) calculations. The quantitative relation between primary knock-on atom (PKA) energy and irradiation damage on graphite was calculated. and the effect of PKA direction on the amount of defects is estimated by counting displaced atoms. Defects are classified into four groups: structural defects, energy defects, vacancies, and near-defect structures, where a structural defect is further subdivided into six types by decision tree method which is one of the supervised machine learning techniques.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.163-163
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• 2003

Difficulties of long-tenn survival of lung cancer patients treated with conventional therapies require the need for novel approaches and gene therapy holds promise in this area. Several genes are known to have anti-tumor activities and have been used as a gene of delivery, however, a number of problems such as efficiency, specificity of the gene delivery hinder the application of gene therapy.(omitted)

• Hanyang Medical Reviews
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• v.34 no.3
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• pp.130-136
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• 2014

Animals find nutritious foods to survive, while avoiding aversive and toxic chemicals through the chemosensory faculties of olfaction and taste. The olfaction is comparatively well characterized, but the studies of taste are only recently developing since after 2000. Genetic, immunohistochemistry, and electrophysiological studies with knock-out transgenic mice opened up the taste field in mammals. Taste in insects has been only recently been studied after mammalian taste receptors were identified. Flies also discriminate the differences of sweet, salty and sour food, while being able to detect and reject potential foods contaminated with toxins or detrimental chemicals. These discriminatory abilities indicate that flies house basic taste receptors in their taste organs like humans. For the last decade, the sweet and bitter gustatory receptors in Drosophila have been characterized. In this review, we compare the taste anatomy between humans and insects. We also introduce five canonical taste sensations in Drosophila. In addition, we introduce new taste repertoires, that fruit flies can sense water and fatty acids as well as the carbonation buffer in beverage. These studies on simple model organisms will open up a new potential for scientists to further investigate these characteristics in vertebrates.

• International Journal of Stem Cells
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• v.17 no.1
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• pp.1-14
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• 2024

The clustered regularly interspaced short palindromic repeats (CRISPR) system, a rapidly advancing genome editing technology, allows DNA alterations into the genome of organisms. Gene editing using the CRISPR system enables more precise and diverse editing, such as single nucleotide conversion, precise knock-in of target sequences or genes, chromosomal rearrangement, or gene disruption by simple cutting. Moreover, CRISPR systems comprising transcriptional activators/repressors can be used for epigenetic regulation without DNA damage. Stem cell DNA engineering based on gene editing tools has enormous potential to provide clues regarding the pathogenesis of diseases and to study the mechanisms and treatments of incurable diseases. Here, we review the latest trends in stem cell research using various CRISPR/Cas technologies and discuss their future prospects in treating various diseases.

• Applied Microscopy
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• v.50
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• pp.27.1-27.6
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• 2020

Transition metal dichalcogenides (TMD), which is composed of a transition metal atom and chalcogen ion atoms, usually form vacancies based on the knock-on threshold of each atom. In particular, when electron beam is irradiated on a monolayer TMD such as MoS₂ and WS₂, S vacancies are formed preferentially, and they are aligned linearly to constitute line defects. And then, a hole is formed at the point where the successively formed line defects collide, and metal clusters are also formed at the edge of the hole. This study reports a process in which the line defects formed in a monolayer WS₂ sheet expends into holes. Here, the process in which the W cluster, which always occurs at the edge of the formed hole, goes through a uniform intermediate phase is explained based on the line defects and the formation behavior of the hole. Further investigation confirms the atomic structure of the intermediate phase using annular dark field scanning transition electron microscopy (ADF-STEM) and image simulation.

• Tuberculosis and Respiratory Diseases
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• v.56 no.2
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• pp.187-197
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• 2004

Background : Nitric Oxide (NO) is a multi-faceted molecule with dichotomous regulatory roles in many areas of biology. NO can promote apoptosis in some cells, whereas it inhibits apoptosis in other cell types. This study was performed to characterize NO-induced cell death in lung epithelial cells and to investigate the roles of cell death regulators including iron, bcl-2 and p53. Methods : A549 cells were used for lung epithelial cells. SNP (sodium nitroprusside) and SNAP (S-nitroso-N-acetyl- penicillamine) were used for NO donor. Cytoxicity assay was done by MTT assay and crystal violet assay. Apoptotic assay was done by fluorescent microscopy after double staining with propidium iodide and hoecst 33342. Iron inhibition study was done with RBCs and FeSO4. For bcl-2 study, bcl-2 overexpressing cells (A549-bcl-2) were used and for p53 study, Western blot analysis and p53 functionally knock-out cells (A549-E6) were used. Results : SNP and SNAP induced dose-dependent cell death in A549 cells and fluorescent microscopy revealed that SNAP induced apoptosis in low doses but necrosis in high doses while SNP induced exclusively necrotic cell death. Iron inhibition study using RBCs and FeSO4 significantly blocked SNAP-induced cell death. And also SNAP-induced cell death was blocked by bcl-2 overexpression. Finally, we found that SNAP activate p53 by Western blot analysis and that SNAP-induced cell death was decreased in the abscence of p53. Conclusion : In lung epithelial cells, NO can induce cell death, more precisely apoptosis in low doses and necrosis in high doses. And iron, bcl-2, and p53 play important roles in NO-induced cell death.

• 대한생식의학회:학술대회논문집
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• 2001.03a
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• pp.195-205
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• 2001

태반 영양배엽 (trophoblast)은 포유동물의 발생과정 중 가장 먼저 분화되는 세포로서, 자궁환경내에서 배아가 착상, 발생, 및 분화하기 위해서 반드시 필요한 태반을 형성하는 색심적인 세포이다. 영양배엽 세포의 분화과정중의 결함은 배아의 사산이나 임신질환 등의 치명적 결과를 초래한다. 하지만, 영양배엽 세포의 분화를 조절하는 분자생물학적인 메카니즘은 아직 규명되지 않고 있다. 영양배엽 세포의 분화를 조절하는 경로를 규경하기 위한 선결과제는 분화된 영양배엽 세포에서만 발현하는 많은 유전자들이 밝혀져야만 한다. 본 연구팀은 최근에 분화된 영양배엽 세포에서만 발현하는 두 종류의 새로운 유전자들을 찾았다. 한 종류는 homeobox를 보유하고 있는 조절 유전자 Psx이고, 다른 한 종류는 임신호르몬인 태반 프로락틴 라이크 단백질 유전자 PLP-C${\beta}$이다. 본 연구과제의 목표는 이들 유전자의 기능과 조절 메카니즘을 규명함으로써, 영양배엽 세포의 분화를 조절하는 조절경로를 밝히는 것이다. 이를 위하여 다음과 같은 일련의 연구를 수행할 것이다. 1) Psx 유전자가 분화된 영양배엽 세포에서만 발현케 하는 조절 메카니즘을 규명하기 위해 functional assays, in vitro footprinting, gel mobility shift assays, 생쥐형질전화, UV crosslinking, Southwestern blot 등의 방법을 통해 Psx 유전자의 cis-acting 요인과 trans-acting factor를 밝혀 분석한다. 2) 영양배엽 세포의 분화조절 경로를 규명하기 위해 random oligonuclotide library screening, DD-PCR, subtractive screening 등의 방법을 이용하여 Psx 유전자에 의해 조절되는 하부유전자를 밝힌다. 3) Psx 유전자를 knock-out시켜 영양배엽 세포가 발달 및 분화하는데 미치는 역할을 밝힌다. 4) Yeast two-hybrid screening방법을 이용하여 태반 프로락틴 유전자의 수용체를 찾아 이들의 신호전달 기전을 밝힌다. 제1차년 연구결과로서, mouse와 rat으로부터 각각 Psx 유전자의 genomic DNA를 클로닝하여, 유전자 구조를 비교한 결과, mouse Psx (mPsx2)는 4개의 exons으로 이루어져 있는 반면에, rat Psx (Psx3)는 3개의 exons으로 구성되어 있었다. 즉, rPsx3는 mPsx2의 exon1이 없었다. Notrhern blot과 in situ hybridization 분석에 의해 mouse와 rat에서 Psx 유전자가 다르게 발현 조절되는 현상을 밝혔다. 실제로 mPsx2와 rPsx3의 5'-flanking지역을 클로닝하여 염기서열 분석 결과 전혀 homology를 찾을 수 없었다. 또한, 이들 각각 promoter의 activity를 luciferase reporter를 이용하여 조사한 결과 Rcho-1 trophoblast cells에서 각기 다른 activity를 보여 주는 것을 발견하였다. Psx 유전자의 transcription start sites는 Primer extension에 의해 밝혔다. 또한 Psx2 유전자를 knock-out 시키기 위해 targeting vector를 Osdupde1에 제작하였다. 본 과제를 시작할 때 새로운 프로락틴 유전자 하나를 클로닝하여 이 유전자를 PLP-I라고 이름을 붙였다. 이 후 이 유전자 (PLP-I)는 PLP-C${\beta}$라고 이름을 붙이게 되었다. Mouse PLP-C${\beta}$ 유전자의 counterpart를 rat에서 찾아 염기서열을 비교한 결과 mouse와 rat에서 PLP-C${\beta}$유전자의 homology는 약 79% (amino acid level)였다. 본 연구과정을 통해 또 하나의 새로운 PLP-C subfamily member를 mouse로부터 클로닝 하였고, 이 유전자를 PLP-C${\gamma}$라 하였다. PLP-C${\beta}$와 PLP-C${\gamma}$의 발현 유형은 Northern blot과 in 냐셔 hybridization 분석에 의해 태반의 제한된 spongitrophoblast와 trophoblast giant cells에서만 발현하는 것을 밝혔다. 놀랍게도 이들 두 새로운 유전자는 alternative splicing에 의해 두 종류의 isoform이 있음을 밝혔다. PLP family member 유전자로서 splicing에 의한 isoforms을 보여 주는 유전자로는 PLP-C${\beta}$와 PLP-C${\gamma}$가 최초이다. 이들 isoform mRNAs의 발현 유형은 RT-PCR 방법을 이용하여 규명하였다. 또 하나의 새로운 발견은 PLP-C${\beta}$와 PLP-C${\gamma}$가 독특한 유전자 구조를 갖고 있었다. 즉, PLP-C${\beta}$는 exon3의 alternative splicing에 의해 5개 혹은 6개의 exons을 갖는 two isoforms이 생긴다. 반면에 PLP-C${\gamma}$는 exon2가 alternative splcing이 되면서 7개의 exons을 갖거나 6개의 exons을 갖는 isoforms을 만든다. 그리고, PLP-C${\gamma}$의 promoter activity를 trophoblast Rcho-l${\gamma}$ 세포주를 이용하여 PLP-C${\gamma}$ 의 1.5 kb 5'-flanking 지역이 trophoblast-specific promoter activity를 갖고 있음을 밝혔다. PLP-C${\gamma}$ 유전자의 transcription start site는 Primer extension에 의해 밝혔다. 제 1차 년도의 연구결과를 토대로, 2차년에서는 다음단계의 연구를 수행하고자 한다. 즉, 1) mPsx2와 rPsx3의 promoter를 비교분석 함으로서 mouse와 rat에서 Psx 유전자가 다르게 조절되는 메카니즘 규명, 2) Psx와 PLP-C 유전자의 promoter에 있는 cis-acting elements 탐색, 3) Psx2와 Psx3의 단백질을 이용하여 이들이 binding하는 target sequence 규명, 4) 제작한 Psx2 targeting vector를 이용하여 ES cells에서 Psx2 유전자 knock-out, 5) Psx 유전자를 과발현시키는 세포주를 만들고 Psx에 의해 조절되는 유전자 탐색, 6) 새로 밝히 PLP-C members 유전자들의 조절기전을 Rcho-1 세포주를 이용하여 여러 거지 성장인자와 다른 호르몬에 대한 반응을 탐색, 7) Psx와 PLP-C${\gamma}$ 유전자의 chromosomal mapping 등을 밝힐 것이다.

• Journal of Life Science
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• v.21 no.9
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• pp.1301-1309
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• 2011

The major function of adipocytes is to store fat in the form of triglycerides. One of the signaling pathways known to affect adipogenesis, i.e. fat formation, is the WNT/${\beta}$-catenin pathway which inhibits the expression and activity of key regulators of adipogenesis. The purpose of this research is to find genes among the WNT/${\beta}$-catenin pathway which regulate adipogenesis by using small interfering (si) RNA and to find the association of single nucleotide polymorphisms (SNPs) of the gene with serum triglyceride levels in the human population. To elucidate the effects of ${\beta}$-catenin siRNA on adipogenesis key factors, PPAR${\gamma}$ and C/EBP${\alpha}$, we performed real-time PCR and western blotting experiments for the analyses of mRNA and protein levels. It was found that the siRNA-mediated knockdown of ${\beta}$-catenin upregulates adipogenesis key factors. However, upstream regulators of the WNT/${\beta}$-catenin pathway, such as DVL2 and LRP6, had no significant effects compared to ${\beta}$-catenin. These results indicate that ${\beta}$-catenin is a candidate gene for human fat accumulation. In general, serum triglyceride level is a good indicator of fat accumulation in humans. According to statistical analyses of the association between serum triglyceride level and SNPs of ${\beta}$-catenin, -10,288 C>T SNP (rs7630377) in the promoter region was significantly associated with serum triglyceride levels (p<0.05) in 290 Korean subjects. On the other hand, serum cholesterol levels were not significantly associated with SNPs of the ${\beta}$-catenin gene. The results of this study showed that ${\beta}$-catenin is associated with fat accumulation both in vitro and in the human population.