Related Experiment Videos
Nitric oxide and peroxynitrite interactions with mitochondria
Rafael Radi1, Adriana Cassina, Roberto Hodara
1Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay. rradi@fmed.edu.uy
Abstract:
Nitric oxide (*NO) and peroxynitrite (ONOO-) avidly interact with mitochondrial components, leading to a range of biological responses spanning from the modulation of mitochondrial respiration, mitochondrial dysfunction to the signaling of apoptotic cell death. Physiological levels of *NO primarily interact with cytochrome c oxidase, leading to a competitive and reversible inhibition of mitochondrial oxygen uptake. In turn, this leads to alterations in electrochemical gradients, which affect calcium uptake and may regulate processes such as mitochondrial transition pore (MTP) opening and the release of pro-apoptotic proteins. Large or persistent levels of *NO in mitochondria promote mitochondrial oxidant formation. Peroxynitrite formed either extra- or intra-mitochondrially leads to oxidative damage, most notably at complexes I and II of the electron transport chain, ATPase, aconitase and Mn-superoxide dismutase. Mitochondrial scavenging systems for peroxynitrite and peroxynitrite-derived radicals such as carbonate (CO3*-) and nitrogen dioxide radicals (*NO2) include cytochrome c oxidase, glutathione and ubiquinol and serve to partially attenuate the reactions of these oxidants with critical mitochondrial targets. Detection of nitrated mitochondrial proteins in vivo supports the concept that mitochondria constitute central loci of the toxic effects of excess reactive nitrogen species. In this review we will provide an overview of the biochemical mechanisms by which *NO and ONOO- regulate or alter mitochondrial functions.
Insights
Nitric oxide (NO) and peroxynitrite (ONOO-) impact mitochondria, affecting respiration, dysfunction, and cell death. Understanding these interactions is key to mitochondrial health and disease.
Area of Science:
- Mitochondrial biochemistry
- Cellular signaling
- Reactive nitrogen species metabolism
Background:
- Nitric oxide (NO) and peroxynitrite (ONOO-) are reactive nitrogen species with significant biological roles.
- Mitochondria are central players in cellular energy production and apoptosis.
- Dysregulation of NO and ONOO- signaling is implicated in various pathologies.
Purpose of the Study:
- To review the biochemical mechanisms by which NO and ONOO- interact with mitochondrial components.
- To elucidate the consequences of these interactions on mitochondrial function and cellular fate.
- To highlight the role of mitochondria as targets for reactive nitrogen species.
Main Methods:
- Literature review of biochemical and cellular studies.
- Analysis of signaling pathways involving NO and ONOO- in mitochondria.
- Examination of oxidative damage to mitochondrial components.
Main Results:
- Physiological NO levels reversibly inhibit cytochrome c oxidase, altering mitochondrial membrane potential and calcium uptake.
- High NO levels induce mitochondrial oxidant formation.
- Peroxynitrite causes oxidative damage to key mitochondrial proteins, including electron transport chain complexes and enzymes.
- Mitochondrial scavenging systems partially mitigate ONOO- toxicity.
- Nitrated mitochondrial proteins are detected in vivo, confirming mitochondria as targets.
Conclusions:
- Mitochondria are critical sites for NO and ONOO- action, influencing respiration, dysfunction, and apoptosis.
- The balance of NO and ONOO- levels dictates their impact on mitochondrial health.
- Understanding these mechanisms is crucial for developing therapeutic strategies against diseases involving reactive nitrogen species.