| Project/Area Number |
18390047
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Medical pharmacy
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| Research Institution | The University of Tokyo |
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Principal Investigator |
ITO Kousei The University of Tokyo, Facully of Medicine, Associate Professor (30323405)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Hiroshi The University of Tokyo, Faculty of Medicine, Professor (80206523)
TAKADA Tappei The University of Tokyo, Faculty of Medicine, Assistant Professor (90376468)
HONMA Masashi The University of tokyo, Faculty of Medicine, Assistant Professor (60401072)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥10,900,000 (Direct Cost: ¥9,700,000、Indirect Cost: ¥1,200,000)
Fiscal Year 2007: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
Fiscal Year 2006: ¥5,700,000 (Direct Cost: ¥5,700,000)
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| Keywords | lipids / responses to drugs / intestinal absorption / transporters |
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| Research Abstract |
Cumulative evidence suggests that Niemann-Pick Cl-like 1 (NPClL1) is essential for intestinal cholesterol absorption and is the target of ezetimibe, a novel cholesterol-lowering drug. In this project, we isolated human NPClL1 cDNA and constructed human NPClL1-overexpressing Caco-2 cells. NPClL1 protein was mainly detected on the apical membrane, which reflects the physiological expression of NPClL1 on the intestinal brush border membrane. It was also shown that the transport activities of cholesterol were positively correlated with the expression level of introduced NPClL1 and ezetimibe inhibited the uptake in a concentration-dependent manner. In addition, since it has also been established that the transfer of cholesterol across the plasma membrane via many kinds of transporters and/or receptors is associated with the transfer of phospholipids, we examined whether the uptake of cholesterol by NPClL1 also takes place in the lipid-associated mechanism. It was found that overexpression of NPClL1 results in an increase in the uptake of both cholesterol and phosphatidylcholine from micelles composed of cholesterol, phosphatidylcholine and taurocholate but that the level of transport activity for cholesterol was much higher than that for phosphatidylcholine. In addition, the uptake of phosphatidylcholine was much less sensitive to ezetimibe than the uptake of cholesterol. In contrast, NPClL1-mediated uptake of taurocholate was minimal. It was also demonstrated that the uptake and ezetimibe-sensitivity of phosphatidylcholine and taurocholate from the micelles were not affected by the presence of cholesterol. Taken together, the results suggested that cholesterol is a preferable substrate of NPClL1 in micellar components and the inhibitory effect of ezetimibe is relatively selective to cholesterol uptake, although NPClL1 has potent activity for uptake of phospholipids from micelles.
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