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PMID:17394422

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Citation

Iñarrea, P, Moini, H, Han, D, Rettori, D, Aguiló, I, Alava, MA, Iturralde, M and Cadenas, E (2007) Mitochondrial respiratory chain and thioredoxin reductase regulate intermembrane Cu,Zn-superoxide dismutase activity: implications for mitochondrial energy metabolism and apoptosis. Biochem. J. 405:173-9

Abstract

IMS (intermembrane space) SOD1 (Cu/Zn-superoxide dismutase) is inactive in isolated intact rat liver mitochondria and is activated following oxidative modification of its critical thiol groups. The present study aimed to identify biochemical pathways implicated in the regulation of IMS SOD1 activity and to assess the impact of its functional state on key mitochondrial events. Exogenous H2O2 (5 microM) activated SOD1 in intact mitochondria. However, neither H2O2 alone nor H2O2 in the presence of mitochondrial peroxiredoxin III activated SOD1, which was purified from mitochondria and subsequently reduced by dithiothreitol to an inactive state. The reduced enzyme was activated following incubation with the superoxide generating system, xanthine and xanthine oxidase. In intact mitochondria, the extent and duration of SOD1 activation was inversely correlated with mitochondrial superoxide production. The presence of TxrR-1 (thioredoxin reductase-1) was demonstrated in the mitochondrial IMS by Western blotting. Inhibitors of TxrR-1, CDNB (1-chloro-2,4-dinitrobenzene) or auranofin, prolonged the duration of H2O2-induced SOD1 activity in intact mitochondria. TxrR-1 inactivated SOD1 purified from mitochondria in an active oxidized state. Activation of IMS SOD1 by exogenous H2O2 delayed CaCl2-induced loss of transmembrane potential, decreased cytochrome c release and markedly prevented superoxide-induced loss of aconitase activity in intact mitochondria respiring at state-3. These findings suggest that H2O2, superoxide and TxrR-1 regulate IMS SOD1 activity reversibly, and that the active enzyme is implicated in protecting vital mitochondrial functions.

Links

PubMed PMC1925252 Online version:10.1042/BJ20061809

Keywords

Aconitate Hydratase/metabolism; Animals; Antimycin A/analogs & derivatives; Antimycin A/pharmacology; Apoptosis/physiology; Cell Respiration/physiology; Cytochromes c/metabolism; Electron Transport/physiology; Energy Metabolism; Enzyme Activation; Hydrogen Peroxide/metabolism; Male; Membrane Potentials/physiology; Mitochondria, Liver/drug effects; Mitochondria, Liver/metabolism; Oxidants/metabolism; Rats; Rats, Wistar; Superoxide Dismutase/metabolism; Superoxides/metabolism; Thioredoxin-Disulfide Reductase/metabolism

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

RAT:SODC

located_in

GO:0005758: mitochondrial intermembrane space

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:SODC

part_of

GO:0005758: mitochondrial intermembrane space

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

Notes

See also

References

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