| Project/Area Number |
13308052
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biomedical engineering/Biological material science
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| Research Institution | The University of Tokyo |
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Principal Investigator |
ANDO Joji The University of Tokyo, Graduate School of Medicine, Professor, 大学院・医学系研究科, 教授 (20159528)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Kimiko The University of Tokyo, Graduate School of Medicine, Research Associate, 大学院・医学系研究科, 助手 (00323618)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥41,470,000 (Direct Cost: ¥31,900,000、Indirect Cost: ¥9,570,000)
Fiscal Year 2002: ¥10,660,000 (Direct Cost: ¥8,200,000、Indirect Cost: ¥2,460,000)
Fiscal Year 2001: ¥30,810,000 (Direct Cost: ¥23,700,000、Indirect Cost: ¥7,110,000)
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| Keywords | endothelial cells / intracellular signal transduction / calcium signaling / purinoceptor / transcription factor Sp1 / calcium ion channel / fluid shear stress / blood vessel / 細胞内情報伝 / イオンチャンネル / ATP / 細胞内情報伝達 |
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| Research Abstract |
Our previous study demonstrated that a subtype of P2X purinoceptor, P2X4, is predominantly expressed in human vascular ECs and plays a central role in blood flow-related Ca^<2+> signaling. In the current study, we investigated the effect of shear stress on P2X4 receptor expression in ECs. When Cultured human umbilical vein ECs (HUVECs) were exposed to physiological levels of laminar shear stress in a flow-loading apparatus, the P2X4 mRNA levels began to decrease as early as 1 h after the onset of flow and decreased progressively with time, reaching around 60% of the static control at 24 h. The P2X4 protein levels also decreased significantly. Functional analysis of the 1.9-kb P2X4 5'promoter indicated that a region containing a consensus binding site for the Sp1 transcription factor between bp -67 and -58 was required for the shear stress responsiveness. Mutations of the Sp1 site abolished the response of the P2X4 promoter to shear stress. Electrophoretic mobility shift assays showed a marked decrease in binding of Sp1 to the Sp1 consensus site in shear stressed cells, suggesting that Sp1 mediates the shear stress-induced down regulation of P2X4 gene transcription. Superoxide dismutase (SOD) and a peroxide-scavenging enzyme catalase significantly inhibited the shear stress-induced decrease in the P2X4 mRNA levels, indicating that reactive oxygen species play a role, at least partially, in shear stress-mediated regulation of P2X4 gene expression in ECs. We also show that shear-induced changes in purinoceptor expression attenuate the sensitivity of ECs to ATP causing Ca^<2+> responses. Thus there may be a feedback system in our body, which controls the sensitivity of ECs to shear stress via blood flow-mediated attenuation of purinoceptor expression to maintain vasucular homeostasis.
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