Effects of overexpression of antioxidants on the release of cytochrome c and apoptosis-inducing factor in the model of ischemia.
Apoptosis arises from neuronal damage following an ischemic insult. Apoptosis-inducing factor (AIF) is a protein released from mitochondria in response to pro-apoptotic signals which then translocates to the nucleus and triggers DNA fragmentation. In parallel with this, pro-apoptotic signals cause the release of cytochrome c from mitochondria, activating caspase-dependent apoptosis. During post-ischemic reperfusion, reactive oxygen species (ROS) are formed in excess in mitochondria and can play a role in initiating apoptosis. In cultures, ROS are formed during post oxygen glucose deprivation (OGD) normoxia/normoglycemia that is used as a model for ischemia. In this study, we delivered viral vectors to overexpress antioxidants (GPX, catalase, CuZnSOD, or MnSOD) in mixed cortical cultures, in order to investigate the effects of ROS-reduction on the release of cytochrome c and AIF. Overexpression of MnSOD, CuZnSOD, catalase or GPX all prevented AIF translocation from mitochondria to the nucleus. Potentially, this could reflect broadly non-specific protection due to reducing ROS load. Arguing against this, overexpression of the same antioxidants did not inhibit cytochrome c release. These findings suggest a specific interaction between ROS formation and the caspase-independent route of apoptosis.
Department Biological Sciences, 371 Serra Street, Stanford University, Stanford, CA, United States. ilonaz@stanford.edu
Ilona
I
Zemlyak
Sheila M
SM
Brooke
Maneesh H
MH
Singh
Robert M
RM
Sapolsky
D000818:Animals; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism*; D002374:Catalase / Q000096:biosynthesis* / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D018920:Coculture Techniques; D003300:Copper; D045304:Cytochromes c / Q000378:metabolism*; D005822:Genetic Vectors; D005979:Glutathione Peroxidase / Q000096:biosynthesis* / Q000235:genetics; D018259:Herpesvirus 1, Human / Q000235:genetics; D008345:Manganese; D008928:Mitochondria / Q000378:metabolism; D021381:Protein Transport; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000096:biosynthesis* / Q000235:genetics; D015032:Zinc
C494831:Aifm1 protein, rat; D051033:Apoptosis Inducing Factor; D017382:Reactive Oxygen Species; D008345:Manganese; D003300:Copper; D045304:Cytochromes c; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D015032:Zinc