title: Redox regulation of the intrinsic pathway in neuronal apoptosis.
abstract: Two principal pathways exist by which cells can undergo apoptotic death, known as the extrinsic and the intrinsic pathways. Binding of a ligand to a death receptor activates the extrinsic pathway. In the intrinsic pathway, an apoptotic stimulus, such as neurotrophin withdrawal or exposure to a toxin, causes a proapoptotic member of the Bcl-2 family of proteins, such as Bax, to permeabilize the outer mitochondrial membrane. This allows redistribution of cytochrome c from the mitochondrial intermembrane space into the cytoplasm, where it causes activation of caspase proteases and, subsequently, cell death. A dramatic increase occurs in mitochondria-derived reactive oxygen species (ROS) during the apoptotic death of sympathetic, cerebellar granule, and cortical neurons. These ROS lie downstream of Bax in each cell type. Here I review possible mechanisms by which Bax causes increased ROS during neuronal apoptosis. I also discuss evidence that these ROS are an important part of the apoptotic cascade in these cells. Finally, I discuss evidence that suggests that neurotrophins prevent release of cytochrome c in neurons through activation of an antioxidant pathway.
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 Green St., Athens, GA 30602, USA. jlfrankl@rx.uga.edu
authors.forename: James L
authors.initials: JL
authors.lastname: Franklin
mesh_terms: D000818:Animals; D017209:Apoptosis; D045304:Cytochromes c / Q000378:metabolism; D006801:Humans; D009414:Nerve Growth Factors / Q000378:metabolism; D009474:Neurons / Q000378:metabolism* / Q000473:pathology*; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D009414:Nerve Growth Factors; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c
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