2003 Fiscal Year Final Research Report Summary
Cell biological functions of phosphoinositides-phosphorylation of 5-position
| Project/Area Number |
14580690
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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 | The University of Tokyo |
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Principal Investigator |
SHIBASAKI Yoshikazu The University of Tokyo, Research Center for Advanced Science and Technology, Professor, 先端科学技術研究センター, 科学技術振興特任教員(特任教授) (80196419)
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| Project Period (FY) |
2002 – 2003
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| Keywords | vesicular traffic / actin / endocytosis / inositol / kinase / cytoskeleton |
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| Research Abstract |
For vesicular traffic, the interaction between molecules on vesicles and cytoplasmic proteins is important. In this study, we focused on phosphoinositides (PI) on the vesicular membrane and its phosphorylation. Phosphorylation of PI is regulated by phosphatidylinositol kinases and phosphatases. Especially, phosphatidylinositol (4,5) bisphosphate (PIP2) is important for membrane traffic. The final step of PIP2 production is catalyzed by phosphatidylinositol phosphate 5-kinases (PIP5K). PIP5K increased actin polymerixzation in cells. For intracellular vesicles, polymerized actin was very often associated with one side of vesicles and vesicles moved around with polymerized actin tails. Similar movement was observed in host cells infected by bacterial pathogens. At the interface between vesicle membrane and cytoplasm, increased PIP2 recruited N-WASP (Wiscott- Aldrich syndrome protein) by inositol binding region and induced conformational change. This results in the activation of its C-terminal domain to induce actin polymerization. By live cell imaging using green fluorescent protein (GFP) derivatives, we could observe dynamic intracellular vesicular movement. These results suggest that, in addition to vesicle movement on microtubules, actin polymerization is likely to contribute intracellular vesicular movement and that the levels of phosphoinositides regulate this actin based motility.
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