title: Progressive apoptotic cell death triggered by transient oxidative insult in H9c2 rat ventricular cells: a novel pattern of apoptosis and the mechanisms.
abstract: Many pathophysiological processes are associated with oxidative stress and progressive cell death. Oxidative stress is an apoptotic inducer that is known to cause rapid cell death. Here we show that a brief oxidative insult (5-min exposure to 400 microM H(2)O(2)), although it did not kill H9c2 rat ventricular cells during the exposure, triggered an intracellular death cascade leading to delayed time-dependent cell death starting from 1 h after the insult had been withdrawn, and this post-H(2)O(2) cell death cumulated gradually, reaching a maximum level 8 h after H(2)O(2) withdrawal. By comparison, sustained exposure to H(2)O(2) caused complete cell death within a narrow time frame (2 h). The time-dependent post-H(2)O(2) cell death was typical of apoptosis, both morphologically (cell shrinkage and nuclear condensation) and biochemically (DNA fragmentation, extracellular exposure of phosphatidylserines, and caspase-3 activation). A dichlorofluorescein fluorescent signal showed a time-dependent endogenous increase of reactive oxygen species (ROS) production, which was almost abolished by inhibition of the mitochondrial electron transport chain. Application of antioxidants (vitamin E or DTT) before H(2)O(2) addition or after H(2)O(2) withdrawal prevented the H(2)O(2)-triggered progressive ROS production and apoptosis. Sequential appearance of events associated with activation of the mitochondrial death pathway was found, including progressive dissipation of mitochondrial membrane potential, cytochrome c release, and late activation of caspase-3. In conclusion, transient oxidative stress triggers an intrinsic program leading to self-sustained apoptosis in H9c2 cells via cumulative production of mitochondrial ROS and subsequent activation of the mitochondrial death pathway. This pattern of apoptosis may contribute to the progressive and long-lasting cell loss in some degenerative diseases.
authors.affiliation: Research Center, Montreal Heart Institute, 5000 Belanger East, Montreal, Quebec, Canada H1T 1C8.
authors.forename: Hong
authors.initials: H
authors.lastname: Han
authors.forename: Hong
authors.initials: H
authors.lastname: Long
authors.forename: Huizhen
authors.initials: H
authors.lastname: Wang
authors.forename: Jingxiong
authors.initials: J
authors.lastname: Wang
authors.forename: Yiqiang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D006352:Heart Ventricles / Q000166:cytology / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D016877:Oxidants; D017382:Reactive Oxygen Species; D014810:Vitamin E; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C505410:Casp3 protein, rat; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases