Elucidation of novel functions of cholesterol and its metabolites using genetic manipulation in mice

• Project/Area Number: 17390266
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Metabolomics
• Research Institution: Jichi Medical University
• Principal Investigator: ISHIBASHI Shun Jichi Medical University, Department of Medicine, Professor (90212919)
• Co-Investigator(Kenkyū-buntansha): YAGYU Hiroaki Jichi Medical Univetsity, Department of Medicine, Assistant Professor (60348018) ; TAZOE Fumiko Jichi Medical Univetsity, Department of Medicine, Post Graduated Student (20406127) ; NAGASHIMA Shuichi Jichi Medical Univelsity, Department of Medicine, Post Graduated Student (30406136) ; WANG Xiao li Jichi Medical Univetsity, Department of Medicine, Post Graduated Student (10458325) ; TAKAHASHI Manabu Jichi Medical Univetsity, Department of Medicine, Post Graduated Student (70406122) ; 加藤 秀樹 自治医科大学, 医学部, 研究生 (20406094) ; 板橋 直樹 自治医科大学, 医学部, 助手 (00316522)
• Project Period (FY): 2005 – 2007
• Project Status: Completed (Fiscal Year 2007)
• Budget Amount: ¥13,810,000 (Direct Cost: ¥12,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2007: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2006: ¥3,700,000 (Direct Cost: ¥3,700,000); Fiscal Year 2005: ¥5,300,000 (Direct Cost: ¥5,300,000)
• Keywords: cholesterol / HMG-CoA reductase / squalene synthase / liver / albumin / mouse / knockout / liver dysfunction / HMG-CoA還元酵素 / スクアレン合成酵素 / 血管平滑筋細胞 / ミエリン / 細胞増殖

Research Abstract

Cholesterol biosynthetic pathway is divided into two pathways: sterol pathway and non-sterol pathway. Then non-sterol pathway supplies various substances such as isoprenoids, dolichol, Haem A and ubiquinones. HMG-CoA reductase (HMGCR) produces mevalonate which is a precursor of both sterol and non-sterol pathways, whereas squalene synthase (SS) produces squalene which contributes only to sterol pathway. In the present study, we used Cre-LoxP system to disrupt genes of HMGCR or SS in a liver-specific manner to dissect out the functions of the respective enzymes in the liver. Liver-specific HMGCR knockout mice (L-HMGCRKO) were lethal at 1 month after the birth due to fulminant hepatic failure. Plasma cholesterol levels were reduced only by 10% and hepatic cholesterol biosynthesis was not reduced. mRNA expression of SREBP2 was induced, while expression of Cyp7A was reduced. The hepatocytes were filled with triglycerides. Liver-specific SS knockout mice (L-SSKO) showed transient hepatomegaly with liver dysfunction. Although hepatic VLDL production rate was reduced, hepatic cholesterol biosynthesis was not reduced at least in in vivo setting. In conclusion, HMGCR is essential for normal liver function and survival, while SS is dispensable. Normal cholesterol biosynthesis in both models suggests the presence of metabolic bypass pathway which produces cholesterol in the absence of these key enzymes in cholesterol biosynthesis.

Research Products

• [Journal Article] Hormone-sensitive lipase is involved in hepatic cholesterol ester hydrolysis (2008)
  • Author(s): Sekiya, M., et. al.
  • Journal Title: J Lipid Res (in press)
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] Cholesterol reduction and atherosclerosis of inhibition by bezafibrate in low density lipoprotein receptor knockout mice (2008)
  • Author(s): Inaba, T., et. al.
  • Journal Title: Hypertens Res (in press)
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] Ligand-independent activation of vascular endothelial growth factor receptor 1 by low-density lipoprotein (2007)
  • Author(s): Usui, R., et. al.
  • Journal Title: EMBO Rep 8 Pages: 1155-1161
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] Sterol regulatory element-binding protein(SREBP)-1-independent regulation of lipogenic gene expression in adipocytes (2007)
  • Author(s): Sekiya, M., et. al.
  • Journal Title: J Lipid Res 48 Pages: 1581-1591
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] Ligand-independent activation of vascular endothelial growth factor receptor 1 by low-density lipoprotein (2007)
  • Author(s): Usui, R., Shibuya, M., Ishibashi, S., Maru, Y
  • Journal Title: EMBO Rep 8(12) Pages: 1155-1161
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Sterol regulatory element-binding protein(SREBP) -1-independent regulation of lipogenic gene expression in adipocytes (2007)
  • Author(s): Sekiya, M., Yahagi, N., Matsuzaka, T., Takeuchi, Y., Nakagawa, Y., Takahashi, H., Okazaki, H., Iizuka Y, Ohashi, K., Gotoda, T., Ishibashi, S., Nagai, R., Yamazaki, T., Kadowaki, T., Yamada, N., Osuga, JI., Shimano, H
  • Journal Title: J Lipid Res 48(7) Pages: 1581-1591
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Ligand-independent activation of vascular endothelial growth factor receptor 1 by low-density lipoprotein. (2007)
  • Author(s): Usui, R., Ishibashi, S., et. al.
  • Journal Title: EMBO Rep 8 Pages: 1155-1161
  • Peer Reviewed
• [Journal Article] Sterol regulatory element-binding protein(SREBP)-1-independent regulation of lipogenic gene expression in adipocytes. (2007)
  • Author(s): Sekiya, M., Ishibashi, S., et. al.
  • Journal Title: J Lipid Res 48 Pages: 1581-1591
  • Peer Reviewed
• [Journal Article] Identification of a novel member of the carboxylesterase family that hydrolyzes triacylglycerol: a potential role in adipocyte lipolysis (2006)
  • Author(s): Okazaki, H., et. al.
  • Journal Title: Diabetes 55 Pages: 2091-2097
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] Increased cholesterol biosynthesis and hypercholesterolemia in mice overexpressing squalene synthase in the liver (2006)
  • Author(s): Okazaki, H., et. al.
  • Journal Title: J Lipid Res 47 Pages: 1950-1958
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] Identification of a novel member of the carboxylesterase family that hydrolyzes triacylglycerol : a potential role in adipocyte lipolysis (2006)
  • Author(s): Okazaki, H., Igarashi, M., Nishi, M., Tajima, M., Sekiya, M., Okazaki, S., Yahagi, N., Ohashi, K., Tsukamoto, K., Amemiya-Kudo, M., Matsuzaka, T., Shimano, H., Yamada, N., Aoki, J., Morikawa, R., Takanezawa, Y., Arai, H., Nagai, R., Kadowaki, T., Osuga, J., Ishibashi, S
  • Journal Title: Diabetes 55(7) Pages: 2091-2097
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Increased cholesterol biosynthesis and hypercholesterolemia in mice overexpressing squalene synthase in the liver (2006)
  • Author(s): Okazaki, H., Tazoe, F., Okazaki, S., Isoo, N., Tsukamoto, K., Sekiya, M., Yahagi, N., Iizuka, Y., Ohashi, K., Kitamine, T., Tozawa, R., Inaba, T., Yagyu, H., Okazaki, M., Shimano, H., Shibata, N., Arai, H., Nagai, R.Z., Kadowaki, T., Osuga, J., Ishibashi, S
  • Journal Title: J Lipid Res 47 Pages: 1950-1958
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Identification of a novel member of the carboxylesterase family that hydrolyzes triacylglycerol : a potential role in adipocyte lipolysis. (2006)
  • Author(s): Okazaki, H., Ishibashi, S., et al.
  • Journal Title: Diabetes 55 Pages: 2091-2097
• [Journal Article] Increased cholesterol biosynthesis and hypercholesterolemia in mice overexpressing squalene synthase in the liver. (2006)
  • Author(s): Okazaki, H., Ishibashi, S., et al.
  • Journal Title: J Lipid Res 29 Pages: 1950-1958
• [Journal Article] High cholesterol level is essential for myelin membrane growth (2005)
  • Author(s): Saher, G., et. al.
  • Journal Title: Nature Neuroscience 8 Pages: 468-475
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] High cholesterol level is essential for myelin membrane growth (2005)
  • Author(s): Saher, G., Brugger, B., Lappe-Siefke, C., Mobius, W., Tozawa, R., Wehr, M. C., Wieland, F., Ishibashi, S., Nave, K.A
  • Journal Title: Nature Neuroscience 8 Pages: 468-475
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] High cholesterol level is essential for myelin membrane growth. (2005)
  • Author(s): G.Saher, S.Ishibashi, et al.
  • Journal Title: Nat Neurosci 8 Pages: 468-475
• [Journal Article] Cholesterol reduction and atherosclerosis of inhibition by bezafibrate in low density lipoprotein receptor knockout mice
  • Author(s): Inaba, T. Yagyu, H. Itabashi, N. Tazoe, F. Fujita, N. Nagashima, S. Okada, K. Okazaki, M. Furukawa, Y. Ishibashi, S
  • Journal Title: Hypertens Res (in press)
  • NAID: 10021935912
  • Description: 「研究成果報告書概要(欧文)」より
• [Presentation] 肝臓特異的スクアレン合成酵素欠損マウスにおける血清・肝臓の脂質代謝の検討 (2007)
  • Author(s): 永島 秀一、野牛 宏晃、田副 文子、石橋 俊, 他
  • Organizer: 第39回日本動脈硬化学会総会・学術集会,
  • Place of Presentation: 大阪
  • Year and Date: 2007-07-13
• [Presentation] 肝臓特異的スクアレン合成酵素欠損マウスにおける血清及び肝臓の脂質代謝の検討 (2007)
  • Author(s): 永島 秀一, 他
  • Organizer: 第39回日本動脈硬化学会
  • Place of Presentation: 大阪
  • Description: 「研究成果報告書概要(和文)」より
• [Presentation] Lipid metabolism in liver-sepecific squalene synthase knockout mice. (2007)
  • Author(s): Nagashima, S., Yagyu, H., Tazoe, F., Ishibashi, S., et. al.
  • Organizer: The 39th Annual Scientific Meeting of the Japan Atherosclerosis Society
  • Place of Presentation: Osaka
  • Description: 「研究成果報告書概要(欧文)」より
• [Presentation] コレステロール合成系酵素群を欠損させた血管平滑筋細胞における増殖能の検討 (2006)
  • Author(s): 田副 文子, 他
  • Organizer: 第38回日本動脈硬化学会
  • Place of Presentation: 東京
  • Description: 「研究成果報告書概要(和文)」より
• [Presentation] A comparative study on the disruption of 3-hydroxy-3-Methylglutaryl coenzyme A reductase or squalene synthase (2006)
  • Author(s): Tazoe, F., et. al.
  • Organizer: American Heart Association Scientific Sessions 2006
  • Place of Presentation: Chicago
  • Description: 「研究成果報告書概要(和文)」より
• [Presentation] Cell proliferation of vascular smooth muscle cells with defective cholesterol biosynthesis (2006)
  • Author(s): Tazoe, F., Yagyu, H., Nagashima, S., Ishibashi, S., et. al.
  • Organizer: The 38th Annual Scientific Meeting of the Japan Atherosclerosis Society
  • Place of Presentation: Tokyo
  • Description: 「研究成果報告書概要(欧文)」より
• [Presentation] ssential role of non-sterol pathway in the proliferation of vascular smooth muscle cells : A comparative study on the disruption of 3-hydroxy-3-Methylglutaryl coenzyme A reductase or squalene synthase (2006)
  • Author(s): Tazoe, F., Yagyu, H., Itabashi, N., Ohashi, K., Tozawa, R., Inaba, T., Nagashima, S., Kato, K., Khadbaatar, Z., Osuga, J., Ishibashi, S
  • Organizer: American Heart Association Scientific Sessions 2006
  • Place of Presentation: Chicago
  • Description: 「研究成果報告書概要(欧文)」より
• [Book] Hormone-sensitive lipase is involved in hepatic cholesterol ester hydrolysis
  • Author(s): Sekiya, M., Osuga, JI., Yahagi, N., Okazaki, H., Tamura, Y., Igarashi, M., Takase, S., Harada, K., Okazaki, S., Iizuka, Y., Ohashi, K., Yagyu, H., Okazaki, M., Gotoda, T., Nagai, R., Kadowaki, T., Shimano, H., Yamada, N., Ishibashi, S
  • Publisher: J Lipid Res in press
  • Description: 「研究成果報告書概要(欧文)」より