| Project/Area Number |
14370223
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Mie University |
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Principal Investigator |
ITO Masaaki Mie University Hospital, Department of Cardiology, Lecturer, 医学部附属病院, 講師 (00223181)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIDA Kyoko Mie University, Faculty of Medicine, Department of Pathology, Lecturer, 医学部, 講師 (00242967)
ONISHI Katsuya Mie University, Faculty of Medicine, Depatment of Laboratory Medicine, Assistant, 医学部, 助手 (40343222)
SUZUKI Noboru Life Science Research Center, Experimenta Animal Facilities, Associate Professor, 生命科学研究支援センター, 助教授 (00202135)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥14,100,000 (Direct Cost: ¥14,100,000)
Fiscal Year 2004: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2003: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2002: ¥9,900,000 (Direct Cost: ¥9,900,000)
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| Keywords | Rho-kinase / RhoA / Myosin phosphatase / MYPT2 / MYPT1 / Myosin light chain phosphorylation / Ca^<2+> sensitization / Cardiomyocyte |
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| Research Abstract |
The roles of RhoA/Rho-kinase/myosin phosphatase (MP) signaling in heart and its involvement in cardiac diseases had been investigated.
Myosin phosphatase target subunit 2 (MYPT2) could interact with a catalytic subunit of type 1 phosphatase δ isoform (PP1cδ) and HS-M_<21> to form a cardiac myosin phosphatase holoenzyne. MYPT2 was identified to be a target of the active form of RhoA. Rho-kinase phosphorylated MYPT2 and its thiophosphorylation could induce the inhibition of MP activity. The cultured rat neonatal cardiomyocytes overexpressing MYPT2-PP1cδ showed the lower levels of myosin light chain 2 (MLC2) phosphorylation and were resistant to the sarcomere organization induced by angitensin II, indicating that MYPT2-PP1cδ could act as MP and was involved in sarcomere organization.
The heart of the cardiac-specific MYPT2-PP1cδ transgenic mice (Tg) showed the dilated cardiomyopathy-like phenotypes, including the enlargement of LV dimension, thinning of LV wall and the reduced fractional sh
… More
ortening. The papillary muscle of Tg heart showed the reduced Ca^<2+> sensitivity of contraction and the phosphorylation levels of MLC2 were signfficantly lower as compared with wild type. These results suggested that MP play a role to regulate MLC2 phosphorylation and MLC2 phosphorylation level is important to maintain normal cardiac functions in vivo.
To analyze the functions of Rho-kinase in heart, the conditional transgenic mice overexpressing the dominant negative or the constitutively active fragment of Rho-kinase were generated. However, the double transgenic mice of each Tg and heart-specific Cre mice failed to induce an enough amount of each fragment and no phenotypes were observed. Therefore, the conditional transgenic mice overexpressing the active fragment of leukemia-associated Rho guanine nucleotide exchange factors (LARG-Tg) were generated to investigate the Rho/Rho-kinase signaling in heart. We will continue to make the double transgenic mice of LARG-Tg and Cre mice to investigate its phenotypes to understand the role of Rho/Rho-kinase signaling in heart. Less
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