| Project/Area Number |
11680710
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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 |
Cell biology
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| Research Institution | National Institute for Basic Biology |
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Principal Investigator |
YASHIMORI Tamotsu Nat.Inst.Basic Blol.Associate Prof., 基礎生物学研究所, 助教授 (60191649)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2000: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1999: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Autophagy / Apg proteins / LC3 / Beclin / PI 3-kinase / The trans-Golgi network / Membrane traffic / Homologues / 自食作用 / オートファゴソーム / トランスゴルジ網 / ベクリン / 細胞内膜系 / phosphatidylinositol 3-kinase / 酵母遺伝子 / 相同性 / 翻訳後修飾 / 蛋白質複合体 / ES細胞 / 遺伝子破壊 |
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| Research Abstract |
We found that two forms of the rat LC3, a homologue of yeast Apg8p essential for autophagy, are produced from the same gene post-translationally. LC3-I is cytosolic, whereas LC3-II is membrane bound. We confirmed that LC3-II is specifically associated with the autophagosome membranes. LC3-I is formed by the removal of the C-terminal 22 amino acids from newly synthesized LC3, followed by the conversion of a fraction of LC3-I into LC3-II.The amount of LC3-II is correlated with the extent of autophagosome formation. LC3-II is useful for monitoring progression of autophagy.
We generated Apg5-deficient mouse embryonic stem cells, which showed defects in autophagosome formation. The cells also showed a defect in the conversion of LC3-I into LC3-II, indicating a functional relationship between Apg5 and LC3. Apg5 localizes to the isolation membranes and small crescent-shaped compartments. Apg5 was preferentially distributed in an outside of the isolation membranes. Time-lapse video microscopy using GFP-Apg5 demonstrated that the isolation membranes elongated from the small membranes and matured into autophagosomes. Apg5 is covalently conjugated with Apg12 by a novel ubiquitin-like system. The conjugation was required to the elongation of the isolation membranes.
Although it was reported that the decreased level of Beclin, a homologue of the yeast Apg6p, caused a low autophagic activity and tumorigenesis, localization and function of Beclin is unclear. We showed that all Beclin forms a complex with Ptdlns 3-kinase and the majority of the complex localize to the trans-Golgi network (TGN). The results suggest that Beclin functions as a regulatory subunit of the Ptdlns 3-kinase complex regulating supply of autophagosomal components from the TGN.
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