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2000 Fiscal Year Final Research Report Summary

Molecular approach for the mechanism of insulin-stimulated glucose transport

Research Project

Project/Area Number 11470234
Research Category

Grant-in-Aid for Scientific Research (B).

Allocation TypeSingle-year Grants
Section一般
Research Field Metabolomics
Research InstitutionYamaguchi University

Principal Investigator

OKA Yoshitomo  Yamaguchi University, School of Medicine, Professor, 医学部, 教授 (70175256)

Co-Investigator(Kenkyū-buntansha) MASUJIMA Tsutomu  Hiroshima University Hospital, Professor, 医学部, 教授 (10136054)
KATAGIRI Hideki  Tokyo University Hospital, Clinical Fellow, 医学部・附属病院, 医員(臨床)
AOKI Minoru  Yamaguchi University, School of Medicine, Research Associate, 医学部, 助手 (70304475)
TANAKA Keiji  Yamaguchi University Hospital, Clinical Fellow, 医学部・附属病院, 医員(臨床)
INOUE Hiroshi  Yamaguchi University Hospital, Research Associate, 医学部・附属病院, 助手 (20294639)
Project Period (FY) 1999 – 2000
KeywordsInsulin / glucose transport / GLUT4 / PI3 kinase / Akt1 / PDK1
Research Abstract

To investigate the role of 3-phosphoinositide-dependent protein kinase 1 (PDK1) in the Akt1 phosphorylation state, wild-type (wt) PDK1 and its kinase dead (kd) mutant were expressed using an adenovirus gene transduction system in Chinese hamster ovary cells stably expressing insulin receptor. Immunoblotting using anti-phosphorylated Akt1 antibody revealed Thr-308 already to be maximally phosphorylated at 1 min but completely dephosphorylated at 5 min, with insulin stimulation, whereas insulin-induced Akt1 activation was maintained even after dephosphorylation of Thr-308. Overexpression of wt-PDK1 further increased insulin-stimulated phosphorylation of Thr-308, also followed by rapid dephosphorylation. The insulin-stimulated Akt1 activity was also enhanced by wt-PDK1 expression but was maintained even at 15 min. Thus, phosphorylation of Thr-308 is not essential for maintaining the Akt1 activity once it has been achieved. Interestingly, the insulin-stimulated phosphorylation state of Thr-308 was maintained even at 15 min in cells expressing kd-PDK1, suggesting that kd-PDK 1 has a dominant negative effect on dephosphorylation of Thr-308 of Akt1. Calyculin A, an inhibitor of PP1 and PP2A, also prolonged the insulin-stimulated phosphorylation state of Thr-308. In addition, in vitro experiments revealed PP2A, but not PP1, to dephosphorylate completely Thr-308 of Akt1. These findings suggest that a novel pathway involving dephosphorylation of Akt1 at Thr-308 by a phosphatase, possibly PP2A, originally, identified as is regulated downstream from PDK1, an Akt1 kinase.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Yamada T: "3-phosphoinsitide-dependent protein kinase 1, an Akt1 kinase, is involved in dephosphorylation of Thr308 of Akt1 in Chinese hamster ovary cells"J Biol Chem. 276. 5339-5345 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Itoh T: "Autophosphorylation of type I phosphatidylinositol phosphate kinase regulates its lipid kinase activity."J Biol Chem. 275. 19389-94 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Asano T: "p110beta is up-regulated during differentiation of 3T3-L1 cells and contributes to the highly insulin-responsive glucose transport activity."J Biol Chem. 275. 17671-6 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Funaki M: "p85/p110-type phosphatidylinositol kinase phosphorylates not only the D-3, but also the D-4 position of the inositol ring."J Biol Chem. 274. 22019-24 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Hosaka T: "Regulation of insulin-stimulated glucose transport by chronic glucose exposure in 3T3-L1 adipocytes."Endocrine Journal. 46. 349-357 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ishihara H: "Type I Phosphatidylinositol-4-phosphate 5-Kinases. Cloning of the third isoform and deletion/substitution analysis of members of this novel lipid kinase family."J Biol Chem. 273. 8741-8748 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yamada T et al: "3-phosphoinositide-dependent protein kinase 1, an Akt1 kinase, is involved in dephosphorylation of Thr308 of Akt1 in Chinese hamster ovary cells"J Biol Chem. 276. 5339-5345 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Itoh T et al: "Autophosphorylation of type I phosphatidylinositol phosphate kinase regulates its lipid kinase activity."J Biol Chem. 275. 19389-19394 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Asano T et al: "p110 beta is up-regulated during differentiation of 3T3-L1 cells and contributes to the highly insulin-responsive glucose transport activity."Biol Chem. 275. 17671-17676 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Funaki M et al: "p85/p110-type phosphatidylinositol kinase phosphorylates not only the D-3, but also the D-4 position of the inositol ring."J Biol Chem. 274. 22019-24220 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hosaka T et al: "Regulation of insulin-stimulated glucose transport by chronic glucose exposure in 3T3-L1 adipocytes."Endocrine Journal. 46. 349-357 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Ishihara H et al: "Type I Phosphatidylinositol-4-phosphate 5-Kinases. Cloning of the third isoform and deletion/substitution analysis of members of this novel lipid kinase family."J Biol Chem. 273. 8741-4748 (1998)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2002-03-26  

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