A novel effect of insulin on vascular smooth muscle cells through the transcriptional regulation ?the meaning of the activation of C/EBP
| Project/Area Number |
14571090
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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 |
Metabolomics
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| Research Institution | Shiga University of Medical Science |
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Principal Investigator |
NISHIO Yoshihiko Shiga University of Medical Science, Department Medicine, assistant professor, 医学部, 助手 (40281084)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2002: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Insulin / PI3-kinase / CCAAT / enhancer binding protein / smooth muscle cells / transcription / monocyte chemoattractant protein-1 / MCP-1 / PI3-kinases |
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| Research Abstract |
Phosphatidylinositol 3-kinase (PI 3-kinase is a key molecule mediating signals of insulin in vascular smooth muscle cells (VSMCs). To examine the-effect of chronic activation of PI 3-kinase on the gene expression of VSMCs, membrane-targeted p110CAAX, a catalytic subunit of PI 3-kinase, was o overexpressed m rat SMCs by adenovirus-mediated gene transfer. Similar to insulin' s effects, cells overexpressing p110CAAX exhibited 10-to 15-fold increase in monocyte chemoattractant protein-1 (MCP-1) mRNA expression as compared with the control cells. Electrophoretic mobility shift assay showed that the overexpression of p110CAAX activated neither the NF-κB binding nor the activator protein (AP-1) binding activities. To investigate the mechanisms for the induction of MCP-1 gene expression by p110CAAX, 3.6 kb of the upstream region of MCP-1 gene was cloned and the promoter activity was analyzed by luciferase reporter assay. We found that two CCAAT/enhancer binding protein (C/EBP) binding sites located between 2.6 and 3.6 kb upstream of the MCP-1 gene were responsible for the induction by p110CAAX. The overexpression of C/EBP-β and C/EBP-δ but not C/EBP-α caused 6-to 8-fold induction of MCP-1 promoter activity. Consistently, the overexpression of p110CAAX induced mRNA expression and nuclear expression of CIEBP-β and C/EBP-δ in VSMCs. Insulin at 1 to 10 nM also increased nuclear expression of C/EBP-βand C/EBP-δ in VSMCs. These results clearly indicate that the activation of PI 3-kinase induced proinflammatory gene expression through activating C/EBP-β and CIEBP-δ but not NF-κB, which may explain the proinflammatory effect of insulin in the insulin-resistant state.
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Report
(3 results)
Research Products
(18 results)
