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Frost, Jennifer M.,Kim, M. Yvonne,Park, Guen Tae,Hsieh, Ping-Hung,Nakamura, Miyuki,Lin, Samuel J. H.,Yoo, Hyunjin,Choi, Jaemyung,Ikeda, Yoko,Kinoshita, Tetsu,Choi, Yeonhee,Zilberman, Daniel,Fischer, R National Academy of Sciences 2018 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.115 No.20
<▼1><P><B>Significance</B></P><P>The chromatin remodeling activities of the FACT (facilitates chromatin transactions) complex are required for many cellular functions, including transcription, DNA replication, and repair. Here, we demonstrate that the two FACT subunits, SSRP1 and SPT16, are also required for genome-wide DNA demethylation and regulation of gene imprinting during <I>Arabidopsis</I> reproduction. Without FACT, <I>Arabidopsis</I> seeds undergo abnormal development and exhibit aberrant DNA hypermethylation, including at imprinting control region loci. We show that FACT associates with the DEMETER (DME) DNA demethylase, facilitating DNA demethylation at over half of DME’s targets, specifically those which reside in heterochromatin. These results provide insight into upstream events in the DNA demethylation pathway and reveal the importance of chromatin remodeling for DNA demethylation during <I>Arabidopsis</I> reproduction.</P></▼1><▼2><P>The DEMETER (DME) DNA glycosylase catalyzes genome-wide DNA demethylation and is required for endosperm genomic imprinting and embryo viability. Targets of DME-mediated DNA demethylation reside in small, euchromatic, AT-rich transposons and at the boundaries of large transposons, but how DME interacts with these diverse chromatin states is unknown. The STRUCTURE SPECIFIC RECOGNITION PROTEIN 1 (SSRP1) subunit of the chromatin remodeler FACT (facilitates chromatin transactions), was previously shown to be involved in the DME-dependent regulation of genomic imprinting in <I>Arabidopsis</I> endosperm. Therefore, to investigate the interaction between DME and chromatin, we focused on the activity of the two FACT subunits, SSRP1 and SUPPRESSOR of TY16 (SPT16), during reproduction in <I>Arabidopsis</I>. We found that FACT colocalizes with nuclear DME in vivo, and that DME has two classes of target sites, the first being euchromatic and accessible to DME, but the second, representing over half of DME targets, requiring the action of FACT for DME-mediated DNA demethylation genome-wide. Our results show that the FACT-dependent DME targets are GC-rich heterochromatin domains with high nucleosome occupancy enriched with H3K9me2 and H3K27me1. Further, we demonstrate that heterochromatin-associated linker histone H1 specifically mediates the requirement for FACT at a subset of DME-target loci. Overall, our results demonstrate that FACT is required for DME targeting by facilitating its access to heterochromatin.</P></▼2>
KIM, KI CHEON,PIAO, MEI JING,HEWAGE, SUSARA RUWAN KUMARA MADDUMA,HAN, XIA,KANG, KYOUNG AH,JO, JIN OH,MOK, YOUNG SUN,SHIN, JENNIFER H.,PARK, YEUNSOO,YOO, SUK JAE,HYUN, JIN WON UNKNOWN 2016 INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE Vol.37 No.1
<P>The aim of this study was to identify the mechanisms through which dielectric-barrier discharge plasma damages human keratinocytes (HaCaT cells) through the induction of oxidative stress. For this purpose, the cells were exposed to surface dielectric-barrier discharge plasma in 70% oxygen and 30% argon. We noted that cell viability was decreased following exposure of the cells to plasma in a time-dependent manner, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The levels of intracellular reactive oxygen species (ROS) were determined using 2′,7′-<B>dichlorodihydro</B>-fluorescein diacetate and dihydroethidium was used to monitor superoxide anion production. Plasma induced the generation of ROS, including superoxide anions, hydrogen peroxide and hydroxyl radicals. N-acetyl cysteine, which is an antioxidant, prevented the decrease in cell viability caused by exposure to plasma. ROS generated by exposure to plasma resulted in damage to various cellular components, including lipid membrane peroxidation, DNA breaks and protein carbonylation, which was detected by measuring the levels of 8-isoprostane and diphenyl-1-pyrenylphosphine assay, comet assay and protein carbonyl formation. These results suggest that plasma exerts cytotoxic effects by causing oxidative stress-induced damage to cellular components.</P>
Turning mechanism of a smooth body by amplitude and period control in curvature
Daeyeon Kim,Hyejin Hwang,Sungsu Park,Jennifer H. Shin 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
C. elegans’crawling locomotion including simple running and turning is analyzed with a mathematical model. C. elegans moves forward and backward by propagating dorso-ventral contraction waves toward the opposite direction of its movement. For straight run, the worm maintains a constant amplitude and period in its body curvature. While it changes these quantities during smooth turn. Two types of smooth turn are described theoretically based on the experimental observation. One has the turning strategy to increase both of amplitude and period of the curvature. The other is characterized by decrement of these parameters. Our results may contribute to understanding the lateral undulation of other smooth body animals like snakes and these could further be applied to the developments of bio-inspired robots.
Johnston, Jennifer H,Kim, Hee Kyung,Merrow, Arnold C,Laor, Tal,Serai, Suraj,Horn, Paul S,Kim, Dong Hoon,Wong, Brenda L American Roentgen Ray Society, etc.] 2015 American Journal of Roentgenology Vol.205 No.2
<P>OBJECTIVE. The purpose of this study was to validate derived T2 maps as an objective measure of muscular fat for discrimination between boys with Duchenne muscular dystrophy (DMD) and healthy boys. SUBJECTS AND METHODS. Forty-two boys with DMD (mean age, 9.9 years) and 31 healthy boys (mean age, 11.4 years) were included in the study. Age, body mass index, and clinical function scale grade were evaluated. T1-weighted MR images and T2 maps with and without fat suppression were obtained. Fatty infiltration was graded 0-4 on T1-weighted images, and derived T2 fat values (difference between mean T2 values from T2 maps with and without fat suppression) of the gluteus maximus and vastus lateralis muscles were calculated. Group comparisons were performed. The upper limit of the 95% reference interval of T2 fat values from the control group was applied. RESULTS. There was no significant difference in age or body mass index between groups. All healthy boys and 19 boys (45.2%) with DMD had a normal clinical function scale grade. Grade 1 fatty infiltration was seen in 90.3% (gluteus maximus) and 71.0% (vastus lateralis) of healthy boys versus 33.3% (gluteus maximus) and 52.4% (vastus lateralis) of boys with DMD. T2 fat values of boys with DMD were significantly longer than in the control group (p < 0.001). Using a 95% reference interval for healthy boys for the gluteus maximus (28.3 milliseconds) allowed complete separation from boys with DMD (100% sensitivity, 100% specificity), whereas the values for the vastus lateralis (7.28 milliseconds) resulted in 83.3% sensitivity and 100% specificity. CONCLUSION. Measurement of muscular fat with T2 maps is accurate for differentiating boys with DMD from healthy boys.</P>
Differentiation of fibroblast through NGF by uniaxial tension
Mina Kim(김미나),J.W. Hong(홍정우),Minsoo Nho(노민수),Yong Joo Na(나용주),Jennifer H. Shin(신현정) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Mechanical tension plays an important role in the homeostasis of connective tissue fibroblast. Differentiation of fibroblast to myofibroblasts is related to late stage of wound healing process, stimulating fibroblast to produce collagen. Previous studies have shown that the external NGF induces a-SMA expression in conjunctival fibroblasts through TGF-β1. Our previous data shows that both NGF and TGF transcription exhibit tensile stress dependent behavior which could lead to enhancement of wound healing. We investigate the effects of uniaxial tensile stress on the expression of a-SMA, distinction between fibroblast and myofibroblast, through increase of NGF. Uniaxial tension lead to a-SMA express on the fibroblast and external NGF and TGF treatment induces stress fiber containing α-SMA. Our results may imply that the induction of a-SMA is a consequence of regulation of NGF and TGF by uniaxial tension in fibroblasts.
Building a successful fertility preservation program at a major cancer center
Jayeon Kim,Kenneth H Kim,Jennifer E Mersereau 대한부인종양학회 2014 Journal of Gynecologic Oncology Vol.25 No.2
Over 150,000 reproductive age individuals face fertility-threatening cancer treatments each year. Improved detection and treatment of cancer in reproductive-age patients have greatly increased the long-term survival and made it possible for these individuals to consider their long-term quality-of-life after cancer including having biologic offspring. Various methods of fertility preservation (FP) are now available for both males and females. In order to maximize FP options available to patients facing imminent gonadotoxic therapies, it is crucial that women have quick access to FP care and that providers expedite FP strategies. The overarching goal of a clinical FP program is to help patients and their physicians consider the impact of treatment on future fertility and facilitate FP efforts in what is often a limited time period before cancer treatment begins.