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J Biol Chem. 2002 Mar 22;277(12):10244-50. Epub 2002 Jan 10.

Direct activation of mitochondrial apoptosis machinery by c-Jun N-terminal kinase in adult cardiac myocytes.

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  • 1Department of Molecular Cardiovascular Biology, Yamaguchi University School of Medicine, Minami Kogushi, Ube, Yamaguchi 755-8505, Japan. haoki@po.cc.yamaguchi-u.ac.jp

Abstract

Although oxidative stress causes activation of c-Jun N-terminal kinase (JNK) and apoptosis in many cell types, how the JNK pathway is connected to the apoptosis pathway is unclear. The molecular mechanism of JNK-mediated apoptosis was investigated in adult rat cardiac myocytes in culture as a model system that is sensitive to oxidative stress. Oxidative stress caused JNK activation, cytochrome c release, and apoptosis without new protein synthesis. Oxidative stress-induced apoptosis was abrogated by dominant negative stress-activated protein kinase/extracellular signal-regulated kinase kinase-1 (SEK1)-mediated inhibition of the JNK pathway, whereas activation of the JNK pathway by constitutively active SEK1 was sufficient to cause apoptosis. Inhibition of caspase-9, an apical caspase in the mitochondrial apoptosis pathway, suppressed oxidative stress-induced apoptosis, whereas inhibition of caspase-8 had no effect, indicating that both the JNK pathway and the mitochondrial apoptosis machinery are central to oxidative stress-induced apoptosis. Both JNK and SEK1 localized on mitochondria where JNK was activated by oxidative stress. Furthermore, active JNK caused the release of apoptogenic factors such as cytochrome c from isolated mitochondria in a cell-free assay. These findings indicate that the JNK pathway is a direct activator of mitochondrial death machinery without other cellular components and provide a molecular linkage from oxidative stress to the mitochondrial apoptosis machinery.

PMID:
11786558
[PubMed - indexed for MEDLINE]
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