| Project/Area Number |
14037240
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Biological Sciences
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| Research Institution | Nara Institute of Science and Technology |
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Principal Investigator |
KOHNO Kenji Nara Institute of Science and Technology, Department of Cell Biology, Professor (50142005)
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| Co-Investigator(Kenkyū-buntansha) |
TSURU Akio Nara Institute of Science and Technology, Department of Cell Biology, Assistant Professor (80273861)
木俣 行雄 奈良先端科学技術大学院大学, 遺伝子教育研究センター, 助手 (60263448)
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| Project Period (FY) |
2002 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥139,300,000 (Direct Cost: ¥139,300,000)
Fiscal Year 2006: ¥24,600,000 (Direct Cost: ¥24,600,000)
Fiscal Year 2005: ¥24,600,000 (Direct Cost: ¥24,600,000)
Fiscal Year 2004: ¥26,100,000 (Direct Cost: ¥26,100,000)
Fiscal Year 2003: ¥36,500,000 (Direct Cost: ¥36,500,000)
Fiscal Year 2002: ¥27,500,000 (Direct Cost: ¥27,500,000)
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| Keywords | ER stress / chaperone / quality control of proteins / stress-sensing / 小胞体 / 転写調節 / シグナル伝達 / 構造異常蛋白質 / unfolded protein response / 小胞体シャペロン / BiP / Ire1 / GFP / XBP1 / IRE1 / スプライシング / UPR / Bip / DnaJ |
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| Research Abstract |
In order to analyze the sensing mechanism of endoplasmic reticulum (ER)-stress at the molecular level, we have done systematic mutagenesis of N-terminal luminal region of ER stress sensor Ire1 in budding yeast. This result shows that the luminal region is divided into five subregions I to V and that subresions II and IV are essential for stress recognition. ER chaperone BiP associates subregion V under normal condition and the dissociation of BiP from Ire1 is required for the activation of unfolded protein response (UPR), which maintains the homeostasis of the ER under ER stress. However, dissociation of BiP from Ire1 is not sufficient for the activation of Ire1, another step is needed for full activation. Immunofluorescence and immunoelectron microscopic studies, reporter assay using various Ire1-luminal region mutants, and biochemical analysis of direct interaction between Ire1-luminal domain and unfolded proteins in vitro, these data suggested that activation of Ire1 is regulated by two steps. In the first step, BiP dissociation from Ire1 leads to its cluster formation, and in the second step, direct interaction of unfolded proteins with the core region induces the orientation of cytosolic domain of Ire, resulting in the full activation of Ire1.
We also analyzed the role of novel ER transmembrane protein, DNAJB12, which belongs to Hsp40 DnaJ protein family and locates in the ER membrane. Overexpression of DNAJB12 accelerates the degradation of CFTR (Cystic fibrosis transmembrane conductance regulator) by ERAD, while the knock down of DNAJB12 increases the formation and maturation of CFTR.
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