2003 Fiscal Year Final Research Report Summary
Analysis of molecular mechanism in cardiomyocyte differentiation and its application for regeneration medicine using embryonic stem cells
| Project/Area Number |
13557060
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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 | 展開研究 |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HAYASHI Doubun The University of Tokyo, Faculty of Medicine, Guest Associate Professor, 医学部附属病院, 寄付講座教員(常勤形態) (80313104)
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| Co-Investigator(Kenkyū-buntansha) |
永井 良三 東京大学, 医学部附属病院, 教授 (60207975)
山崎 力 東京大学, 医学部附属病院, 客員助教授(常勤形態) (60251245)
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| Project Period (FY) |
2001 – 2003
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| Keywords | embryonic stem cell / HMGA2 / P19CL6 / cardiomyocyte differentiation / BMP / Csx / Nkx2-5 / regeneration medicine / molecular biology |
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| Research Abstract |
Csx/Nkx2-5 is an important regulator of cardiac development. Many different human CSX/NKX2-5 mutations have been reported to cause congenital heart disease. We examined the effects of three representative CSX/NKX2-5 mutants on cardiomyocyte differentiation and death using P19CL6 cells, which efficiently differentiate into cardiomyocytes. Stable overexpression of wild-type CSX/NKX2-5 enhanced expression of cardiac-specific genes and the terminal differentiation of P19CL6 into cardiomyocytes, while all CSX/NKX2-5 mutants attenuated them. When exposed to stress like H_2O_2 stimulation, many cells overexpressing the mutants were dead, whereas the cells overexpressing the wild-type survived. Thus, we showed that Csx/Nkx2-5 plays a critical role not only in regulating expression of cardiac-specific genes but in protecting cardiomyocytes from stresses (Biochem Biophys Res Commun 298: 493-500, 2002).
Members of the high-mobility-group proteins A(HMGA) family have been reported to be expressed abundantly in fetus and play a critical role in various biological processes as a transcriptional co-factor. By the differential display method, we isolated HMGA2, a member of the HMGA family, whose expression was markedly enhanced during differentiation of P19CL6. Interestingly, stable overexpression of wild-type HMGA2 strongly enhanced cardipmyocyte differentiation of P19CL6, while overexpression of a mutant of HMGA2 inhibited it. We also found that the Csx/Nkx2-5 promoter was transactivated by Smad1, an important mediator of signals from bone morphogenetic proteins (BMPs), and that Smadi and HMGA2 formed complexes and displayed synergistic transacriptional activation of the promoter. Together with our previous reports demonstrating that BMP signaling is essential for cardiomoycyte differentiation, we showed that HMGA2 plays a key role in cardiomyocyte differentiation through accelerating the BMP-Smad-Csx/Nkx2-5 cascade (paper in submission).
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