Direct Activation of Mitochondrial Apoptosis Machinery by c-Jun N-terminal Kinase in Adult Cardiac Myocytes

• Published in: The Journal of biological chemistry 2002-03, Vol.277 (12), p.10244-10250
• Main Authors: Aoki, Hiroki, Kang, Peter M., Hampe, James, Yoshimura, Koichi, Noma, Takafumi, Matsuzaki, Masunori, Izumo, Seigo
• Format: Article
• Language: English
• Subjects: Adenoviridae - genetics; Animals; Apoptosis; Blotting, Western; Caspase 8; Caspase 9; Caspases - metabolism; Cell Death; Cell-Free System; Cells, Cultured; Cytochrome c Group - metabolism; Cytosol - metabolism; Enzyme Activation; Hydrogen Peroxide - pharmacology; In Situ Nick-End Labeling; JNK Mitogen-Activated Protein Kinases; MAP Kinase Signaling System; Microscopy, Confocal; Microscopy, Electron; Mitochondria - metabolism; Mitogen-Activated Protein Kinase 8; Mitogen-Activated Protein Kinases - metabolism; Myocardium - cytology; Myocardium - metabolism; Oxidative Stress; Phosphorylation; Protein Binding; Rats; Recombinant Proteins - metabolism; Subcellular Fractions - metabolism; Time Factors
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112355200

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, cytochromec 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.