2005 Fiscal Year Final Research Report Summary
Tyrosine phosphorylation of heat shock protein 90 and tyrosine kinase in eNOS activation
| Project/Area Number |
16590076
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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 |
Biological pharmacy
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| Research Institution | Kyushu University of Health and Welfare |
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Principal Investigator |
TAKAHASHI Satoru Kyushu University of Health and Welfare, First Dept.of Biochem., Professor, 薬学部, 教授 (20268098)
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| Co-Investigator(Kenkyū-buntansha) |
SUGIYAMA Akinori Kyushu University of Health and Welfare, First Dept.of Biochem., Professor, 薬学部, 講師 (40260319)
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| Project Period (FY) |
2004 – 2005
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| Keywords | nitric oxide / heat shock protein 90 / vascular endothelial cell / phosphorylation / regulation / src |
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| Research Abstract |
We examined significance of tyrosine phosphorylation of HSP90 in VEGF- and bradykinin-induced eNOS activation. VEGF and bradykinin caused eNOS-HSP90-Akt complex formation where eNOS and HSP90 were phosphorylated at Ser1177 and tyrosine residues, respectively, leading to an increase in NO production in vascular endothelial cells. Tyrosine kinase inhibitors abrogated both phosphorylation of eNOS and HSP90, the complex formation, and the increased NO production in response to the ligands. To investigate an activity of phosphorylated HSP90 (pHSP90), in vitro studies using purified proteins were conducted. Binding affinity of pHSP90 for eNOS and the stimulatory effect of pHSP90 on eNOS activity were significantly higher than those of normal HSP90. Similarly, pHSP90 binding to Akt was also greater than normal HSP90 binding. However, HSP90s had no effects on Akt kinase activity. When eNOS, HSP90 and Akt were all mixed, pHSP90 more rapidly formed ternary complex than normal HSP90. These effects of HSP90s were prevented by geldanamycin. These results demonstrate that tyrosine phosphorylation promotes HSP90 binding to both eNOS and Akt, contributing to eNOS activation by rapid formation of eNOS-HSP90-Akt complex.
In addition, src family-specific inhibitor PP2 also inhibited both HSP90 phosphorylation and eNOS activation in response to bradykinin in endothelial cells. Purified active src phosphorylated HSP90 in vitro. Src-phosphorylated HSP90 bound eNOS more than normal HSP90. These results suggest that src might be a protein kinase responsible for tyrosine phosphorylation of HSP90.
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