The initiation of cardiac differentiation has been a topic of vigorous investigation, and many transcription factors have been described as regulators of the genesis of cardiomyocytes from mesodermal stem cells and the subsequent activation of genes responsible for cardiac contractility and morphogenesis. However, the mechanisms regulating transcriptional activity of cardiac transcription factors, especially at the post-translational level, are largely unknown in early cardiogenesis. Our preliminary results point to a role for Rho kinase in inhibiting cardiac cell differentiation and in regulating cardiac morphogenesis. We observed that both p160ROCK and ROKalpha, two members of the Rho kinase family, are expressed in early mouse embryos before the onset of cardiac differentiation, and p160ROCK is highly enriched in the developing heart. Treatment of early stage chick embryos with a specific pharmacological Rho kinase inhibitor (Y27632) induced precocious expression of cardiac alpha-actin (an early marker of cardiomyocyte differentiation), cardia bifida, an open neural tube and abnormal left-right asymmetry. In cell culture, we observed that Rho kinase phosphorylates SRF, a critical transcription factor in mesoderm specification and cardiac differentiation, and selectively inhibits SRF transcriptional activity on the cardiac alpha-actin promoter. It is thus important to investigate the role of Rho kinase in mammalian cardiac development by a direct genetic approach. We have successfully generated p160ROCK deficient mice for loss-of-function studies.
The Specific Aims of this proposal are: 1) to determine the spatial-temporal regulation of Rho kinase expression and activity during cardiomyocyte differentiation; 2) to demonstrate the role of Rho kinase in mammalian cardiac development through Rho kinase knockout and conditional knockout mouse models; 3) to determine if Rho kinase selectively represses SRF-dependent cardiac gene expression in undifferentiated cardiac cells through direct phosphorylation of SRF. The proposed study will elucidate fundamental roles of Rho kinase in mammalian cardiogenesis and embryogenesis, and gain insight into the mechanisms by which Rho kinase regulates cardiomyocyte differentiation. Understanding the mechanisms of cardiomyocyte differentiation not only has fundamental importance for understanding heart development, but also has important implications for the possibility of cardiac repair through genetic manipulation of embryonic stem cells.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL072897-01
Application #
6598359
Study Section
Cardiovascular and Pulmonary Research A Study Section (CVA)
Program Officer
Schramm, Charlene A
Project Start
2003-04-01
Project End
2008-03-31
Budget Start
2003-04-01
Budget End
2004-03-31
Support Year
1
Fiscal Year
2003
Total Cost
$338,625
Indirect Cost
Name
Baylor College of Medicine
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
051113330
City
Houston
State
TX
Country
United States
Zip Code
77030
Yang, Xiangsheng; Li, Qi; Lin, Xi et al. (2012) Mechanism of fibrotic cardiomyopathy in mice expressing truncated Rho-associated coiled-coil protein kinase 1. FASEB J 26:2105-16
Shi, Jianjian; Zhang, Yi-Wei; Yang, Yu et al. (2010) ROCK1 plays an essential role in the transition from cardiac hypertrophy to failure in mice. J Mol Cell Cardiol 49:819-28
Zhang, Yi-Wei; Shi, Jianjian; Li, Yuan-Jian et al. (2009) Cardiomyocyte death in doxorubicin-induced cardiotoxicity. Arch Immunol Ther Exp (Warsz) 57:435-45
Lee, Dae Ho; Shi, Jianjian; Jeoung, Nam Ho et al. (2009) Targeted disruption of ROCK1 causes insulin resistance in vivo. J Biol Chem 284:11776-80
Shi, Jianjian; Zhang, Yi-Wei; Summers, Lelia J et al. (2008) Disruption of ROCK1 gene attenuates cardiac dilation and improves contractile function in pathological cardiac hypertrophy. J Mol Cell Cardiol 44:551-60
Shah, Viraj R; Koster, Maranke I; Roop, Dennis R et al. (2007) Double-inducible gene activation system for caspase 3 and 9 in epidermis. Genesis 45:194-9
Shi, Jianjian; Wei, Lei (2007) Rho kinase in the regulation of cell death and survival. Arch Immunol Ther Exp (Warsz) 55:61-75
Chang, Jiang; Xie, Min; Shah, Viraj R et al. (2006) Activation of Rho-associated coiled-coil protein kinase 1 (ROCK-1) by caspase-3 cleavage plays an essential role in cardiac myocyte apoptosis. Proc Natl Acad Sci U S A 103:14495-500
Zhang, Ying-Min; Bo, Jacqueline; Taffet, George E et al. (2006) Targeted deletion of ROCK1 protects the heart against pressure overload by inhibiting reactive fibrosis. FASEB J 20:916-25
Iyer, Dinakar; Chang, David; Marx, Joe et al. (2006) Serum response factor MADS box serine-162 phosphorylation switches proliferation and myogenic gene programs. Proc Natl Acad Sci U S A 103:4516-21

Showing the most recent 10 out of 15 publications