| Project/Area Number |
17590739
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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 | Yamaguchi University |
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Principal Investigator |
IKEDA Yasuhiro Yamaguchi University, School of Medicine・Department of Molecular Cardiovascular Biology, Assistant Professor, 医学部, 助手 (00260349)
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| Co-Investigator(Kenkyū-buntansha) |
YANO Masafumi Yamaguchi University, Hospital・Division of Cardiovascular Medicine, Associate professor, 医学部附属病院, 講師 (90294628)
AOKI Hiroki Yamaguchi University, School of Medicine・Department of Molecular Cardiovascular Biology, Associate Professor, 医学部, 助教授 (60322244)
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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: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | gene transfer / heart failure / molecular therapy / calcium handling / sarcoplasmic reticulum / protein phosphatase 1 / アイソフォーム / 蛋白ホスファターゼ1 / 慢性心不全 / 拡張型心筋症 / アデノウイルスベクター / アデノ随伴ウイルスベクター / 心筋症ハムスター / 高効率遺伝子導入 / Inhibitor-2 |
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| Research Abstract |
We previously reported that overactivation of protein phosphatase 1 (PP 1) is responsible for the decrease in phospholamban (PLN) phosphorylation and concomitant decrease in cardiac contractility in the failing heart. In this regard, increased expression level in PP 1β was evident in failing cardiomyopathic hamster hearts. However, specific role of each PP 1 isoform in cardiomyocytes is unclear. We therefore investigated the isoform specific role of PP 1 in contractility and phosphorylation regulation using adenoviral RNA interference (RNAi) technique.
Methods : We created recombinant adenoviruses encoding short hairpin RNA, that induce isoform-specific RNAi for PP 1 a (Ad.PP1ai), 1β (Ad.PP1βi), and γ (Ad.PP1γi) in normal adult rat cardiomyocytes at 8-10 weeks of age. Isolated cardiomyocytes were transfected with each adenoviral vector at MOI of 20, 100, and 500, followed by the analysis for phosphorylation, cell shortening and intracellular calcium transient 72 hours after transfection. Results : All adenoviral RNAi transfection induced approximately 90% decrease in mRNA expression and significant decrease in protein level ranging from 60 to 80% without affecting other isoform expressions. Expression levels of major regulatory protein including phospholamban (PLN), A kinase (PKA), sarcoendoplasmic reticulum ATPase (SERCA2a), ryanodine receptor type 2 (RyR2) were not affected. Increase in PLN phosphorylation at Ser16 was observed in Ad.PP1ai (1.5 folds) and Ad.PP1βi (2 folds), but not in PP1γ-transfected cardiomyocytes. PP 113i most effectively augmented cell shortening and Ca^<2+> transient among the group at normal culture state, and under the beta-adrenergic stimulated state. Conclusion: PP 1βi appears to be the major PLN phosphatase that regulates cardiomyocyte contractility. Because PP 113 expression is increased in various heart failure models and human heart failure, it may be a good therapeutic target for heart failure.
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