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Jean Ho Yun 한국실험동물학회 2021 한국실험동물학회 학술발표대회 논문집 Vol.2021 No.7
Cellular senescence has been implicated in normal aging. Recent studies demonstrating detrimental role of senescent cells in aging process have triggered many attempts to control senescent cells. In order to improve healthy aging by controlling senescent cell phenotype, a more accurate understanding of molecular mechanism of cellular senescence is essential. We recently found that mitochondrial elongation plays an important role in the induction of cellular senescence. By analyzing tumor suppressor p53-induced cellular senescence model, we revealed that mitochondrial elongation accompanies mitochondrial dysfunction and increases intracellular reactive oxygen species (ROS) levels, an important mediator of cellular senescence. Mechanistical analysis revealed that inhibitory phosphorylation of Drp1 Ser637 was increased upon p53 expression, and the translocation of Drp1 into mitochondria was thereby suppressed. Protein kinase A (PKA) activity is responsible for p53-mediated Drp1 S637 phosphorylation and that the intracellular level of cyclic AMP, a PKA activator, is also increased upon p53 expression. Changes in mitochondrial morphology through the PKA-Drp1 pathway were also observed in IMR90 normal human fibroblasts upon treatment with Nutlin-3a, a small molecular activator of the p53 pathway. We further showed that the PKA-Drp1 pathway plays an important role in mitochondrial dynamics in other types of cellular senescence and senescence of normal cells. Furthermore, the inhibition of PKA activity in late-passage normal cells significantly reduced both mitochondrial elongation and cellular senescence. Our results show that mitochondrial dynamics play an important role in cellular senescence and we, thus, propose that the mitochondrial dynamics of senescent cells could be a promising target for healthy aging.
윤진호,Yun, Jean-Ho Korean Society of Life Science 2005 생명과학회지 Vol.15 No.4
시스플래틴이나 마이토마이신 C (MMC)와 같은 DNA 사슬간 교차결합 (interstrand cross-link ; ICL) 물질에 대해 Brca1 결손세포들이 보이는 높은 감수성은 Brca1 단백질이 세포의 ICL복구반응에 중요한 역할을 담당하고 있음을 암시하고 있다. Brca1 단백질은 재조합 의존성 또는 재조합 비의존성 경로를 통한 DNA 이중사슬 절단(double-strand break ; DSB) 복구에 필수적인 역할을 담당한다. 최근 본인이 속한 연구그룹에서 재조합 의존성 경로를 통한 세포의 ICL복구반응에 Brca1이 관여한다는 것을 밝혀 보고한바 있다. 본 연구에서는 Brca1 단백질의 재조합 비의존성 복구반응에 대한 관여여부를 $p53^{-/-}$와 $p53^{-/-}\;Brcal^{-/-}$ 세포주를 사용하여 연구하였다. 교차결합 복구 실험에서 Brca1 결손 세포주는 Brca1 정상 세포주보다 현저히 낮은 활성을 보였다. 또한, Brca1 결손세포 주의 MMC 에 대한 감수성과 ICL복구능이 Brca1 단백질 발현을 통해 회복되는 것을 확인하였다. 흥미롭게도, Brca1의 11번 엑손 결손세포주 $(Brca1^{\Delta11})$는 높은 MMC저항성과 ICL 복구능을 보였다. 이러한 결과들을 종합하여 볼 때, Brca1 단백질은 ICL복구에 재조합 의존성 경로뿐만 아니라 재조합 비의존성 경로를 통해서도 관여하며, 이러한 활성에는 엑손 11 부분이 아닌 N 말단의 RING 핑거 도메인이나 C 말단의 BRCT도메인이 중요하다는 것을 알 수 있다. Hypersensitivity of cells lacking Brcal to DNA interstrand .ross-link (ICL) agents such as cisplatin and mitomycin C(MMC) implicates the important role of Brcal in cellular response following ICL treatment. Brca1 plays an essential role in DNA double-strand break (DSB) repair through homologous recombination (HR)-dependent and -independent process. Recently, our group has been reported that Brca1 involves in cellular ICL response through HR-dependent repair process (Yun J. et at., Oncogene 2005). In this report, the involvement of Brca1 protein in HR-independent repair process is examined using isogenic $p53^{-/-}\;and\;p53^{-/-}\;Brcal^{-/-}$ mouse embryonic fibroblast (MEF) and psoralen cross-linked reporter reactivation assay. Brcal-deficient MEFs showed significantly low HR-independent repair activity compare to Brca1-proficient MEFs. Hypersensitivity to MMC and ICL reporter repair activity were restored by the reconstitution of Brca1 expression. Interestingly, MEFs expressing exon 11-deleted isoform of Brca1 $(Brca1^{\Delta11/\Delta11})$ showed high resistance to MMC and ICL reporter repair activity comparable to Brca1-reconstituted MEFs. Taken together, these results suggest that Brca1 involves in ICL repair through not only HR-dependent process but also HR-independent process using N-terminal RINC finger domain or C-terminal BRCT domain rather than exon 11 region which mediate interaction with Rad50.
이진호(Jean-Ho Lee),김태윤(Tai-Yun Kim) 한국정보과학회 2001 정보과학회 컴퓨팅의 실제 논문지 Vol.7 No.3
Digital watermarking is a technique for the purpose of protecting the ownership of the image by embedding invisible watermarks in a digital image. To guarantee the security of the digital watermarking scheme for copyright protection, it is required to satisfy some requirements: robustness and perceptual invisibility which provided by the location of embedded bits, the public watermarking algorithm, and the hidden use of the key, which can protect unauthorized accesses from illegal users. For this, in this paper we propose a new copyright watermarking scheme, which is based on one-way hash functions using RSA functions and modular operations. RSA functions are widely used in cryptographic systems. Our watermarking scheme is robust against LSB(least significant bit) attacks and gamma corresction attack, and is also perceptually invisible. We demonstrate the characteristics of our proposed watermarking scheme through experiments. 디지털 워터마킹(digital watermarking)은 기밀 정보를 디지털 이미지 속에 삽입시켜 이미지 소유자의 저작권을 보호하는 것을 목적으로 하는 기법이다. 저작권 보호를 위한 디지털 워터마킹 기법의 안전성을 보장하기 위해서, 삽입 정보의 위치를 결정할 때 워터마킹 공격에 대한 견고성과 육안적 비구별성을 동시에 추구해야 하고, 워터마킹 알고리즘의 은닉성 대신 키의 은닉성이 보장되어야 하며, 키의 사용으로 허가받지 않은 사용자의 워터마크 검출을 방지할 수 있어야 한다. 이를 위해 본 논문에서는 암호학에서 사용되는 일방향 해쉬 함수를 사용하는 워터마킹 기법을 제안한다. 일방향 해쉬 함수를 구현하기 위해 RSA 일방향 함수와 모듈라 연산을 사용한다. 제안하는 워터마킹 기법은 LSB(least significant bit)공격과 감마 보정 공격에 대해 견고하며 육안적 비구별성(perceptual invisibility)이 높다. 제안하는 워터마킹 기법의 실제 구현 및 실험을 통한 실험 결과를 분석하여 견고성과 육안적 비구별성의 특징을 확인한다.
대형 차량 후류 속을 주행하는 Cube형 경차의 항력에 대한 연구
이호원(Ho Won Lee),나선근(Sun Geun Na),김윤제(Yun Je Kim),김창엽(Chang Yup Kim),최지원(Ji Won Choi),이경용(Kyung Yong Lee),박운진(Woon-Jean Park) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
In this research, to analyze the slipstream effect of a compact car in the wake of a large vehicle, flow visualization for the reduced vehicle models in the wind tunnel and flow analysis by means of CFD are carried out. Both results of flow visualization experiment as well as CFD simulation are then analyzed and compared. As a result, the slipstream effect due to the decrease of relative pressure in the wake of a leading vehicle are experimentally verified at a cubic compact car behind a large vehicle in the operating condition of . Therefore it is expected the drag reduction can be achieved by means of slipstreaming technique between a large blunt vehicle and a cubic compact car in the highway transportation.