title: Nitric oxide and cell signaling pathways in mitochondrial-dependent apoptosis.
abstract: Nitric oxide, generated by endogenous nitric oxide synthases or nitric oxide donors, can promote or prevent apoptosis induced by diverse pro-apoptotic stimuli in cell culture models. Both mitochondrial-dependent and -independent apoptotic signaling pathways mediate this dichotomous cellular response to nitric oxide. The molecular mechanisms behind these effects are complex and involve a number of nitrogen oxide-related species that are more reactive than nitric oxide itself. The local cellular environment plays a dynamic role in determining the nature and concentration of these species. Important components of the microenvironment include: the cellular redox state, glutathione, transition metals and the presence of other oxygen- and nitrogen-centered radicals. In particular, redox-sensitive nitrosating species are favorably generated under physiological conditions and capable of modifying multiple cell signaling pathways through reversible S-nitrosation reactions. Cytochrome c release from mitochondria is an important mechanism for the activation of caspase-3 and the initiation of cell death in response to 'intrinsic' pro-apoptotic stimuli, including oxidative and nitrosative stress. In turn, caspases and mitogen associated protein kinases may modulate cytochrome c release through their effects on the Bcl-2 family of proteins. This review will focus on (i) the importance of the cellular environment in determining the fate of nitric oxide and (ii) the ability of S-nitrosation to regulate mitochondrial-dependent apoptosis at the level of mitochondrial bioenergetics, cytochrome c release, caspases, mitogen associated protein kinases, and the Bcl-2 family of proteins.
authors.affiliation: Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles 90089-9121, USA.
authors.forename: Clinton S
authors.initials: CS
authors.lastname: Boyd
authors.forename: Enrique
authors.initials: E
authors.lastname: Cadenas
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D006801:Humans; D008928:Mitochondria / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009569:Nitric Oxide / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D003574:Cytochrome c Group; D009569:Nitric Oxide; D020928:Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases