Identification of respiratory complexes I and III as mitochondrial sites of damage following exposure to ionizing radiation and nitric oxide.
In 32D cl 3 hematopoietic progenitor cells, the overexpression of manganese superoxide dismutase (MnSOD, SOD2), the enzyme normally found in mitochondria, protects against the damaging effects of ionizing radiation. In the presence of a nitric oxide donor, which exacerbates the damage, inhibition of mitochondrial function can be demonstrated to be associated with respiratory complexes I (NADH dehydrogenase) and III (cytochrome c reductase), but not II (succinate dehydrogenase), IV (cytochrome c oxidase), or V (ATP synthase). The same pattern of inhibition is observed in the case of isolated bovine heart mitochondria exposed to ionizing radiation and the nitric oxide donor. The addition of authentic peroxynitrite (ONO2(-)) to isolated mitochondria also results in damage to complexes I and III (but not II, IV, and V), as shown by assays of electron-transfer activities and electron paramagnetic resonance (EPR) spectroscopic measurements, suggesting ONO2(-) to be responsible for most of the observed radiation damage in both the cultured cell lines and isolated mitochondria. It is argued that, in general, production of ONO2(-) is an important contributor to radiation damage in biological systems and the implications of these findings in relation to possible mechanisms of oxidant-linked apoptosis are briefly considered.
Pearce
L L
LL
Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Epperly
M W
MW
Greenberger
J S
JS
Pitt
B R
BR
Peterson
J
J
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002417:Cattle; D002460:Cell Line; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport / Q000187:drug effects; D006207:Half-Life; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects; D007425:Intracellular Membranes / Q000187:drug effects / Q000473:pathology; D008928:Mitochondria / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology / Q000528:radiation effects*; D009245:NADH Dehydrogenase / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology*; D016877:Oxidants / Q000378:metabolism / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D011817:Rabbits; D011839:Radiation, Ionizing; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
D009566:Nitrates; D016877:Oxidants; D013481:Superoxides; C039642:peroxynitric acid; D009569:Nitric Oxide; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D013482:Superoxide Dismutase; D009245:NADH Dehydrogenase