11:10-12:00, Rm 103

OthersU-18-37Mismatch-repair related protein MSH6 regulates DNA double-strandbreak repairJung-Hee LeeDepartment of Bio-materials, Korea DNA Repair Research Center, Chosun University School ofmedicine, 375 Seosuk-Dong, Gwangju 501-759, KoreaMSH6, a key component of the mismatch-repair complex, plays a fundamental role in therepair of mismatched DNA base. Ku70 and Ku86 are two regulatory subunits of the DNAdependentprotein kinase, which plays an essential role in repair of DNA double-strandbreaks (DSBs) through the nonhomologous end-joining (NHEJ) pathway. Herein, wereport that MSH6 is novel Ku70-interacting protein identified by yeast two-hybridscreening. We found that association of Ku70 with MSH6 is enhanced in response totreatment with the radiomimetic drug neocarzinostatin (NCS), a potent inducer of DSBs,and γ-irradiation. MSH6 is also associated with early NHEJ protein including Ku86 andDNA-PKcs, but not late NHEJ protein, XRCC4. Furthermore, MSH6 forms DNA damagefoci after DSBs. Cells depleted of MSH6 accumulate high levels of persistent DSBs, asdetected by formation of γ-H2AX foci and by the comet assay. Moreover, MSH6-deficientcells were also shown to exhibit impaired NHEJ, which could be rescued by MSH6overexpression. MSH6-deficient cells were hypersensitive to IR-, and NCS-induced celldeath, as revealed by clonogenic cell survival assay. The results suggest a potential rolefor MSH6 in DSB repair through upregulation of NHEJ by association with Ku70.U-18-40The HKD regulates ATM-mediated DNA damage responseCha-Kyung Youn, Seon-Joo ParkDepartment of Bio-materials, Korea DNA Repair Research Center, Chosun University School ofmedicine, 375 Seosuk-Dong, Gwangju 501-759, KoreaPosttranscriptional modification of histones, such as acethylation, methylation, andphosphorylation are shown to play important regulatory roles in biological process.Recently, several study reported that posttranslational modification of non-histoneproteins plays an important role of regulation of protein activity. The HKD is a componentof several histone demethylase co-repressor complex. We find that the HKD bind to theataxia telangiectasia mutant (ATM) by yeast two hybrid assay. The ATM protein kinaseregulates the cells response to DNA damage through the phosphorylation of proteinsinvolved in cell-cycle checkpoints and DNA repair. In this study, small interfering RNAmediatedsilencing of HKD decrease foci formation of phosphorylated H2AX and ATMinduced by exposure to ionizing radiation (IR), In addition, the phosphorylation of ATM,H2AX and downstream checkpoint effector, NBS1, Chk2 reduced in HKD-depleted cellsby siRNA. These results reveal that HKD is regulated by phosphorylation of ATM andresults in the activation of ATM-dependent DNA damage response.U-18-38Immunostimulatory effect by water extracts of Hizikia fusiforme inRAW 264.7 cellsJin Hee Kim, Eun Sook LeeDepartment of Herbal Skin Care, Daegu Hanny University, Gyeongsan 712-715, KoreaHizikia fusiforme has been commonly used as food in Korea that possesses potentantibacterial, antifungal, and anti-inflammatory activities. In the study, we investigated theeffect of Hizikia fusiforme water extracts on the activity of nitric oxide (NO), tumornecrosis factor-α(TNF-α), interleukin-1β(IL-1β) and interleukin-6 (IL-6) in RAW 264.7cells. Treatment of RAW 264.7 cells with Hizikia fusiforme water extracts produced amarked induction of NO, TNF-α, IL-1βand IL-6. Moreover, Hizikia fusiforme waterextracts induced the mRNA expression of iNOS, TNF-α, IL-1βand IL-6 in RAW 264.7cells. These results suggest that Hizikia fusiforme water extracts activated the immunefunction by regulating NO TNF-α, IL-1βand IL-6 in RAW 264.7 cells and possess potentimmunomodulatory activity.U-18-41The regulation of RNR2 degradation through Skp1A-mediatedubiquitination pathwayCha-Kyung Youn, Seon-Joo ParkDepartment of Bio-materials, Korea DNA Repair Research Center, Chosun University School ofmedicine, 375 Seosuk-Dong, Gwangju 501-759, KoreaThe RNR2 is a newly identified small subunit of ribonucleotide reductase and plays a keyrole in supplying precursors for DNA repair and mitochondrial DNA replication. It was wellknown about induction of RNR2 by various DNA damage agents in p53-dependentmanner, however little is known mechanism of RNR2 protein degradation. In this study,we investigate molecular mechanism of RNR2 protein degradation. First, we elucidatedthat RNR2 is a short-lived protein, and its half-life is less than 30min in HEK293T cells,and its degradation is inhibited by proteosome inhibitor MG132. And also we elucidatedthat RNR2 protein is degraded by ubiquitin pathway in HEK293T cell through in vitro andin vivo ubiquitination assay. We find that RNR2 protein interact with the Skp1A which is acomponent of SCF(Skip1-Cullin-F-box) complex by yeast two hybrid assay, andinteraction of two proteins was confirmed by immunoprecipitation in mammalian cells. Inthis study, we demonstrate that Skp1A is required for degradation of RNR2 byubiquitination pathway. Taken together, RNR2 protein degrade through ubiquitinationpathway.U-18-39Downregulation of knee joint inflammation by low intensity ultrasound(LIUS) in adjuvant induced arthritisJee-In Chung, Sumit Barua, Eun Joo BaikDepartment of Physiology, Chronic Inflammatory Disease Research Center, Ajou UniversitySchool of Medicine, Suwon 443-749, KoreaArthritis is characterized by intra-articular inflammation, which was accompanied with jointpain, swelling and stiffness leading to significant functional impairment. Thus, theregulation of joint inflammation is a good therapeutic approach to arthritic patient. In thepresent study, we demonstrated the anti-inflammatory effect of LIUS on AIA rat model.LIUS stimulation significantly reduced edema and pro-inflammatory mediators expressionincluding IL-1b, COXs, iNOS and CCR5, which were increased by intra-arthicular FCAinjection. In immunohistochemical analyses, neutrophils and macrophages extremelywere infiltrated into the synovium without LIUS. However, LIUS suppressed therecruitment of immune cells, especially neutrophils. According to statistical analysis, thelevels of pro-inflammatory mediators were strongly correlated with leukocytes infiltrationand edema attenuation. This data suggest that LIUS stimulation attenuate adjuvantinducededema through potent downregulation of synovial inflammation.Acknowledgements This study was supported by Chronic Inflammatory DiseaseResearch Center (KOSEF R-13-2003-019-01005-0) and a grant of the Korean HealthTechnology R&D Project, Ministry for Health, Welfare & Family Affairs, Republic of Korea(A091120).U-18-42Protective role of Drosophila SOD3 against phototoxic damage to cellsInhee Jung and Jeongsil HaDepartment of Molecular Biology, Sejong University, Seoul 143-747, KoreaFor many years, it has been thought that Drosophila lacks extracellular SOD (SOD3).However, there was no direct evidence for this reasoning. A putative SOD3 sequencewas suggested by Landis and Tower (2005) after assembling SOD-related proteinsequences and comparing them using a sequence alignment program. However,whether the predicted SOD3 gene truly functions as a SOD is not yet known. In thepresent study, We investigated whether the predicted SOD3 (dSod3) truly functions as aSOD3 homologue in Drosophila. We found that dSod3 not only retains SOD activity butalso properties of secreted proteins, as do other SOD3s. In addition, dSod3 plays animportant role in both lifespan and protection against oxidative stress. Since we observedprotective effect of externally applied dSod3 against cellular photo-oxidative stressinduced by UV irradiation, this result implies the potential use of SOD3 as antioxidants toreduce UV-induced tissue damage.346 Korean Society for Biochemistry and Molecular Biology