| Project/Area Number |
20591043
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Metabolomics
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| Research Institution | University of Tsukuba |
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Principal Investigator |
KOBAYASHI Kazuto University of Tsukuba, 大学院・人間総合科学研究科, 講師 (30455935)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAGAWA Yoshimi 筑波大学, 大学院・人間総合科学研究科, 講師 (80361351)
SUZUKI Hiroaki 筑波大学, 大学院・人間総合科学研究科, 准教授 (40344890)
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| Project Period (FY) |
2008 – 2010
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| Project Status |
Completed (Fiscal Year 2010)
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| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2010: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2009: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2008: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | メタボリックシンドローム / 脂質代謝 / 遺伝子発現 / 栄養代謝 / 転写因子 / 生活習慣病 / SREBP / PKC / 糖尿病 / インスリン / 糖尿病性腎症 / シグナル伝達 / 高血糖 |
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| Research Abstract |
Sterol-regulatory element binding protein-1c (SREBP-1c) is a transcription factor that controls lipogenesis in the liver. Hepatic SREBP-1c is nutritionally regulated, and its sustained activation causes hepatic steatosis and insulin resistance. Although regulation of SREBP-1c is known to occur at the transcriptional level, the precise mechanism by which insulin signaling activates SREBP-1c promoter remains to be elucidated. Here we show that protein kinase C beta (PKCbeta) is a key mediator of insulin-mediated activation of hepatic SREBP-1c and its target lipogenic genes. Activation of SREBP-1c in the liver of refed mice was suppressed by either adenoviral RNAi-mediated knockdown or dietary administration of a specific inhibitor of protein kinase C beta. The effect of PKCbeta inhibition was cancelled in insulin depletion by streptozotocin (STZ) treatment of mice. Promoter analysis indicated that PKCbeta activates SREBP-1c promoter through replacement of Sp3 by Sp1 for binding to the GC box in the sterol regulatory element (SRE) complex, a key cis-element of SREBP-1c promoter. Knockdown of Sp proteins demonstrated that Sp3 and Sp1 play reciprocally negative and positive roles in nutritional regulation of SREBP-1c, respectively. This new understanding of PKCbeta involvement in nutritional regulation of SREBP-1c activation provides a new aspect of PKCbeta inhibition as a potential therapeutic target for diabetic complications.
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