| Project/Area Number |
17590731
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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 |
Circulatory organs internal medicine
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| Research Institution | Osaka University |
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Principal Investigator |
MINAMINO Tetsuo Osaka University, Graduate School of Medicine, Assistant, 医学系研究科, 助手 (30379234)
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| Co-Investigator(Kenkyū-buntansha) |
TAKASHIMA Seiji Osaka University, Health care Center, Assistant, 保健センター, 助手 (90379272)
HORI Masatsugu Osaka University, Graduate School of Medicine, Professor, 医学系研究科, 教授 (20124779)
KITAKAZE Masafumi National Cardiovascular Center, Department of Cardiovascular Medicine, Director, 生理機能検査部, 部長(研究職) (20294069)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | ubiquitin / proteasome / heart failure / apoptosis / ER stress |
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| Research Abstract |
The endoplasmic reticulum (ER) is recognized as an organelle that participates in folding secretory and membrane proteins. The ER responds to stress by upregulating ER chaperones, but prolonged and/or excess ER stress leads to apoptosis. However, the potential role of ER stress in pathophysiological hearts remains unclear. Cardiac expression of ER chaperones was significantly increased 1 and 4 weeks after transverse aortic constriction (TAC), indicating that pressure overload by TAC induced prolonged ER stress. The CHOP-, but not JNK-or caspase-12-, dependent pathway was activated in failing hearts by TAC. Finally, mRNA levels of ER chaperones were markedly increased in failing hearts of patients. These findings suggest that pressure overload by TAC induces prolonged ER stress, which may contribute to cardiac myocyte apoptosis during progression from cardiac hypertrophy to failure. The ubiquitin-proteasome (U/P) system contributes to regulation of apoptosis degrading apoptosis-regulato
… More
ry proteins. Marked accumulation of ubiquitinated proteins in cardiomyocytes of human failing hearts suggested impaired U/P system in heart failure. Since cardiomyocyte apoptosis contributes to the progression of cardiac dysfunction in pressure-overloaded hearts, we investigated the role of U/P system in such conditions. Proteasome activities already depressed before the onset of cardiac dysfunction in pressure-overloaded hearts of mice. Cardiomyocyte apoptosis was observed along with depression of proteasome activities and elevation of proapoptotic/antiapoptotic protein ratio in failing hearts. In cultured cardiomyocytes, pharmacological inhibition of proteasome accumulated proapoptotic proteins such as p53 and Bax. Gene silencing of these proapoptotic proteins by RNA interference prevented the accumulation of respective proteins and attenuated cardiomyocyte apoptosis induced by proteasome inhibition. We conclude that depression of proteasome activities contributes to cardiac dysfunction resulting from cardiomyocyte apoptosis through accumulation of proapoptotic proteins by impaired degradation. We are now checking the interaction between ER stress and ubiquitin-proteasome system in failing hearts. Less
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