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Metabolism and metabolic diseasesP-18-37Hepatic MGAT1 is directly regulated by PPARγ2 and promotes fattyliverYoo Jeong Lee¹ , ², Jung Hwan Yu¹, Jong Wook Song¹and Jae-woo Kim¹ , ² , ³¹Department of Biochemistry and Molecular Biology, Center for Chronic Metabolic DiseaseResearch, Yonsei University College of Medicine, ²Brain Korea 21 Project for Medical Science,³Department of Integrated OMICS for Biomedical Sciences, Graduate School, Yonsei University,Seoul, KoreaThere are two biochemical patheways for triacylglycerol (TG) synthesis, the glycerol 3-phosphate pathway and the MGAT pathway. In MGAT pathway, monoaylglycerol (MAG)is converted to diacylglycerol (DAG) by MAG acyltransferase 1 (MGAT1). MGAT pathwayis merely involved in the TG biosynthesis because of the very low expression and activityof MGAT1 in normal liver. However, MGAT1 expression increased robustly in liver ofob/ob mice. We found that MGAT1 is up-regulated in high fat fed B6 mice but not in C3Hmice, which do not express PPARγin liver. This indicates that MGAT1 is one of the targetgenes regulated by PPARγ. Moreover, the experiment using adenoviral-PPARγ2 showedthat MGAT1 mRNA level was increased by PPARγ2. Overexpression of MGAT1dramatically increased the lipid droplets, suggesting that MGAT1 is responsible for theincreased TG synthesis. Moreover, B6 mice injected with adenoviral-MGAT1 resulted insignificantly increased TG level in liver. These findings suggest that enhanced TGsynthesis may be due to activated MGAT1 pathway by overexpression of MGAT1,indirectly glycerol 3-phosphate pathway. Taken together, we concluded that PPARγupregulates MGAT1 expression, thereby promoting alternative pathway of TG synthesis,which resulted in the hepatic steatosis.P-18-40Effect of high fat/iron diet on the iron-related gene expression, ironmetabolism and insulin resistance in the animal modelJoo Sun Choi, In-Uk Koh, Hyo Jung Lee, Jihyun SongDivision of Metabolic Diseases, Center for Biomedical Sciences, Korea National Institute of Health,Chungbuk 363-951, KoreaPurpose: Iron affects glucose metabolism, and glucose metabolism impinges on ironmetabolic pathways. The relationship seems to be bi-directional, but unclear yet. Weobserved the change of iron-related gene expression and insulin resistance (IR)parameters in the both diet-induced obesity and iron overloaded animal models.Methods: Iron-related gene expression levels were observed in the liver of male SD ratsfed high-fat diet (HF, 43% energy from fat) or low-fat diet (LF, 12% energy from fat) for 3,7 and 14 weeks. Insulin resistance index and iron status indices were observed in theplasma and the liver of male C57BL6/J mice received LF diet (10% energy from fat) orHF diet (45% energy from fat) containing with or without carbonyl iron (2% of diet weight)for 7 weeks. Results: HF diet caused up-regulation of HAMP, IL6, STAT3, Bmp2 andAlox15 suggesting the increase ofinflammation and oxidative stress. High iron dietsignificantly increased insulin resistance, glucose intolerance and IL6 production. Highiron diet also changed the levels of hepatic iron and plasma iron, ferritin and transferrin.The protein level of hepcidin was higher in the high iron diet group and much higher in HFdiet group.P-18-38Oxidative stress-mediated thrombospondin-2 upregulation contributesto endothelial progenitor cell dysfunction in diabetesOk-Nam Bae¹ , ²and Alex F Chen²¹College of Pharmacy, Hanyang University, Ansan, Gyeonggido 426-791, Korea, and²Department of Pharmacology and Toxicology, Michigan State University, East Lansing,Michigan 48824, USAEndothelial progenitor cells (EPCs) play an essential role in angiogenesis, but aredysfunctional in diabetes. We hypothesized that increased oxidative stress-upregulatedthrombospondin-2 (TSP-2), a potent anti-angiogenic protein, contributing to diabetic EPCdysfunction. Bone marrow-derived EPCs were isolated from adult type 2 diabetic db/dbmice and control db/+ mice. In tube formation assay, angiogenic function was impaired indiabetic EPCs, accompanied by increased oxidative stress and NADPH oxidase. EPCangiogenic function was restored by overexpression of dominant-negative Rac1, whichretards NADPH oxidase subunit Rac1, or by overexpression of MnSOD, whichscavenges superoxide anion. TSP-2 mRNA and protein were both significantlyupregulated in diabetic EPCs, mediated via increased oxidative stress as shown by adecrease in TSP-2 level after overexpression of DN Rac1 or MnSOD. Silencing TSP-2 bysiRNA in diabetic EPCs improved their function in tube formation, adhesion, andmigration assays. Notably, the upregulation of TSP-2 was also observed instreptozotocin-induced type 1 diabetic EPCs, and normal EPCs under high glucoseconditions. In conclusion, TSP-2 upregulation mediated by increased oxidative stresscontributes to angiogenesis dysfunction in diabetic EPCs.P-18-41Overexpression of NAD-dependent MethylenetetrahydrofolateDehydrogenase-Methenyltetrahydrofolate Cyclohydrolase IncreasesLifespan in Drosophila melanogasterSuyeun Yu¹ , ³, Joong-Jean Park² , ³, Yeogil Jang² , ³, Donggi Paik² , ³, Eunil Lee¹ , ³¹Department of Preventive Medicine, ²Department of Physiology, and ³Medical Research Centerfor Environmental Toxico-Genomics and Proteomics, College of Medicine, Korea University, Seoul136-705, KoreaFolate-dependent metabolic enzyme is expressed in the cytoplasm and mitochondria ofeukaryotes. The mitochondrial folate-dependent enzyme generates one-carbon sourcefor thymidylate and purine synthesis, and for methylation in the cytoplasm. The uniquemitochondrial NAD-dependent methylenetetrahydrofolate dehydrogenasemethenyltetrahydrofolatecyclohydrolase (NMDMC) is known to be expressed at muchhigher levels in embryonic and tumor cells compared to normal adult tissues. Nullmutation of nmdmc results in prenatal lethality, but the biological function of this vitalenzyme is yet unclear. Here, we investigated the effect of NMDMC on longevity. UsingGAL4>UAS system in Drosophila, we found that the ubiquitous overexpression of nmdmcsignificantly increased life span in both sexes. Null mutation of the nmdmc causedembryonic lethal. However, conditional inhibition of nmdmc in adult flies by using RNAinterference lines showed the same life span as that of wild-type flies. These resultssuggest that the different expression pattern of nmdmc depending on the developmentalstages would affect the life span of Drosophila. Further analyses are being carried out tounderstand the underlying mechanisms by which NMDMC increases the life span relatedto the development in the fruit flies.P-18-39Kruppel-like transcription factor KLF8 regulates of early adipocytedifferentiationHyo Jung Kim, Hyeonjin Choi, Hye-Min Lee, Hyoun Kyoung Park, Sung-Pil Choiand Jae-woo KimDepartment of Biochemistry and Molecular Biology, Center for Chronic Metabolic DiseaseResearch, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752, KoreaKLF8 (Kruppel-like factor 8) is a zinc-finger transcription factor known to play an essentialrole in oncogenic transformation, cell cycle, apoptosis, tumorigenesis and differentiation.However, the effect of KLF8 on 3T3-L1 differentiation has not been fully elucidated. In thepresent study, we showed that KLF8 acts as a key regulator controlling adipocytedifferentiation. In 3T3-L1 preadipocytes, KLF8 expression was induced at an early stageof differentiation which was followed by expression of PPARγ2 and C/EBPα. The mRNAlevel of KLF8 dramatically increased at 36 h and 48 h during differentiation and theprotein level also gradually increased after 36 h. Knockdown of KLF8 using siRNAsignificantly inhibited differentiation, whereas the cell number was relatively maintained.Furthermore, PPARγ2 and C/EBPαpromoter was drastically activated when KLF8 wasoverexpressed. Taken together, this study provides KLF8 as a key component of thetranscription factor network that controls the terminal differentiation during adipogenesis.P-18-42A novel SIRT1 interacting protein SIP3 negatively regulates PPARactivityJuHyun Kim and Eun Joo KimBK21 Graduate Program, Department of Molecular Biology, Dankook University, Yongin-si,Gyeonggi-do 448-701, KoreaHuman SIRT1 is an NAD+-dependent deacetylase protein that plays a critical role insurvival, apoptosis, senescence, and metabolism. Recently, it has been reported thatSIRT1 specifically associates with PPARγand represses its transcriptional activity,leading to negative regulation of PPARγ-mediated adipogenesis in 3T3-L1 cells. Here, weused a yeast two-hybrid strategy to isolate potential regulators of SIRT1. Among severalisolated clones, we chose a novel protein SIP3 (SIRT1 Interacting Protein 3) for furtherstudy. Systematic yeast two-hybrid assays indicated a physical interaction between theamino acid residues 113-217 of SIRT1 and SIP3. Such interaction was further confirmedby GST pull-down assay in vitro and immunoprecipitation in vivo. In addition, SIRT1colocalized with SIP3 in nucleus as shown by immunofluorescence microscopy. Theintrinsic transcriptional repression activity of SIRT1 was potentiated by SIP3. SIP3significantly inhibited PPARγ-mediated transcriptional activity and thus suppressedadipocyte differentiation of 3T3-L1 preadipocytes. The physiological significance of theinteraction among SIRT1, SIP3, and PPARγis currently being investigated.320 Korean Society for Biochemistry and Molecular Biology