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Proc Natl Acad Sci U S A. 2006 Sep 26;103(39):14495-500. Epub 2006 Sep 18.

Activation of Rho-associated coiled-coil protein kinase 1 (ROCK-1) by caspase-3 cleavage plays an essential role in cardiac myocyte apoptosis.

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  • 1Center for Molecular Development and Disease, Institute of Biosciences and Technology, Texas A&M University System Health Science Center, 2121 West Holcombe Boulevard, Houston, TX 77030, USA.

Abstract

Rho-associated coiled-coil protein kinase 1 (ROCK-1) is a direct cleavage substrate of activated caspase-3, which is associated with heart failure. In the course of human heart failure, we found marked cleavage of ROCK-1 resulting in a 130-kDa subspecies, which was absent in normal hearts and in an equivalent cohort of patients with left ventricular assist devices. Murine cardiomyocytes treated with doxorubicin led to enhanced ROCK-1 cleavage and apoptosis, all of which was blocked by a caspase-3 inhibitor. In addition, a bitransgenic mouse model of severe cardiomyopathy, which overexpresses Gq protein and hematopoietic progenitor kinase-/germinal center kinase-like kinase, revealed the robust accumulation of the 130-kDa ROCK-1 cleaved fragment. This constitutively active ROCK-1 subspecies, when expressed in cardiomyocytes, led to caspase-3 activation, indicating a positive feed-forward regulatory loop. ROCK-1-dependent caspase-3 activation was coupled with the activation of PTEN and the subsequent inhibition of protein kinase B (Akt) activity, all of which was attenuated by siRNA directed against ROCK-1 expression. Similarly, ROCK-1-null mice (Rock-1(-/-)) showed a marked reduction in myocyte apoptosis associated with pressure overload. These data suggest an obligatory role for ROCK-1 cleavage in promoting apoptotic signals in myocardial hypertrophy and/or failure.

PMID:
16983089
[PubMed - indexed for MEDLINE]
PMCID:
PMC1599988
Free PMC Article
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