Mitochondrial NADH–Quinone Oxidoreductase of the Outer Membrane Is Responsible for Paraquat Cytotoxicity in Rat Livers

Shimada, Hiroki; Hirai, Kei-Ichi; Simamura, Eriko; Pan, Jiehong

doi:10.1006/abbi.1997.0557

Cited by 86 publications

(56 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…tase and NADH-coenzyme Q oxidoreductase of the mitochondrial outer membrane (28,33). However, in our intact heart mitochondrial preparations, ϳ90% of NADH consumption was inhibitable by rotenone (data not shown), indicating that most of the observed extramitochondrial PQ reduction by NADH was due to a small proportion of damaged, NADH-permeable mitochondria.…”

mentioning

confidence: 60%

“…ϩ , E 0 ϭ Ϫ446 mV) (1) severely restricts its pool of possible intracellular reductants. However, there are a number of proposed sites for PQ 2ϩ reduction both inside and outside mitochondria including NAD(P)Hdependent flavoenzymes, such as microsomal NADPH-cytochrome P450 reductase (31,32), NADH-cytochrome b 5 oxidoreductase and NADH-coenzyme Q oxidoreductase of the mitochondrial outer membrane (28,33), and complex I of the mitochondrial inner membrane (34). Here we show that PQ 2ϩ is taken up across the mitochondrial inner membrane by a carrier-mediated and membrane potential (⌬ m )-dependent process, and that once in the matrix PQ 2ϩ is reduced to PQ .…”

mentioning

confidence: 99%

See 1 more Smart Citation

Complex I Is the Major Site of Mitochondrial Superoxide Production by Paraquat

Cochemé

Murphy

2008

Journal of Biological Chemistry

509

375

View full text Add to dashboard Cite

Paraquat (1,1-dimethyl-4,4-bipyridinium dichloride) is widely used as a redox cycler to stimulate superoxide production in organisms, cells, and mitochondria. This superoxide production causes extensive mitochondrial oxidative damage, however, there is considerable uncertainty over the mitochondrial sites of paraquat reduction and superoxide formation. Here we show that in yeast and mammalian mitochondria, superoxide production by paraquat occurs in the mitochondrial matrix, as inferred from manganese superoxide dismutase-sensitive mitochondrial DNA damage, as well as from superoxide assays in isolated mitochondria, which were unaffected by exogenous superoxide dismutase. This paraquat-induced superoxide production in the mitochondrial matrix required a membrane potential that was essential for paraquat uptake into mitochondria. This uptake was of the paraquat dication, not the radical monocation, and was carrier-mediated. Experiments with disrupted mitochondria showed that once in the matrix paraquat was principally reduced by complex I (mammals) or by NADPH dehydrogenases (yeast) to form the paraquat radical cation that then reacted with oxygen to form superoxide. Together this membrane potential-dependent uptake across the mitochondrial inner membrane and the subsequent rapid reduction to the paraquat radical cation explain the toxicity of paraquat to mitochondria.Paraquat (1,1Ј-dimethyl-4,4Ј-bipyridinium dichloride; PQ) 2 is used to increase superoxide (O 2 . ) flux when investigating oxidative stress (reviewed in Refs. 1 and 2). The paraquat dication (PQ 2ϩ ) accepts an electron from a reductant to form the paraquat monocation radical (PQ . . and regenerate PQ 2ϩ (Fig. 1A). This redox cycling is a proximal cause of PQ toxicity, as indicated by the protection against PQ by superoxide dismutase (SOD) overexpression or administration of SOD mimetics (4 -8), and by the PQ hypersensitivity caused by SOD deficiency (9 -11).PQ has been used to generate O 2 . in systems ranging from isolated mitochondria (12-15) and cultured mammalian cells (4,14,16,17), to whole organisms including Saccharomyces cerevisiae (18 -21), Caenorhabditis elegans (22, 23), Drosophila melanogaster (9, 24 -26), and rodents (6,11,27). In many of these studies, PQ increases mitochondrial oxidative damage; for example, mitochondrial expression of human peroxiredoxin 5 protects yeast more effectively against PQ toxicity than expression in the cytosol (19); flies overexpressing catalase in mitochondria are resistant to PQ, whereas enhancement of cytosolic catalase was not protective (24); RNA interference silencing of MnSOD (the isoform of superoxide dismutase located in the mitochondrial matrix) in flies causes hypersensitivity to PQ (9), mice heterozygous for MnSOD show greater sensitivity to PQ than wild-type (11), and mitochondrial swelling is one of the earliest ultrastructural changes upon PQ exposure in vivo (28,29). Therefore the interaction of PQ with mitochondria is an important component of its toxicity, and PQ is used in expe...

show abstract

mentioning

confidence: 60%

mentioning

confidence: 99%

Complex I Is the Major Site of Mitochondrial Superoxide Production by Paraquat

Cochemé

Murphy

2008

Journal of Biological Chemistry

509

375

View full text Add to dashboard Cite

show abstract

“…26,27) H 2 O 2 generates the hydroxyl radical by the Fenton reaction and has been reported to form hydroperoxides in both membrane and cytosol with 1 h of incubation in lymphoma cells. 27) It has been reported that the PQ radical was generated by reductase in the microsome fraction or mitochondrial outer membrane, 8,9) and subsequently auto-oxidized to yield the superoxide anion. BSO is an inhibitor of glutathione synthesis, which is one of the most important antioxidants in the cytosol fraction.…”

Section: Discussionmentioning

confidence: 99%

“…7) PQ is taken into the cells and reduced by reductase to generate the paraquat radical, which is reoxidized by molecular oxygen and produces superoxide radicals. 8,9) H 2 O 2 is cell-permeable and decomposes to the hydroxyl radical by a reaction involving transition metal ions that is known as the Fenton reaction.…”

mentioning

confidence: 99%

Effect of Various Radical Generators on Insulin-Dependent Regulation of Hepatic Gene Expression

Kimura

Tawara

Igarashi

et al. 2007

Bioscience, Biotechnology, and Biochemistry

View full text Add to dashboard Cite

“…Lung injury is accompanied by biochemical and ultrastructural changes of the pulmonary capillary endothelium and damage to the alveolar epithelium (Roth et al 1979;Dearden et al 1982;Bus & Gibson 1984). Paraquat is reduced to the paraquat radical by flavoenzymes, such as NADPH-cytochrome P450 reductase (Bus et al 1974;Frank et al 1987;Hara et al 1991), xanthine oxidase (Winterbourn 1981;Kelner et al 1988), and mitochondrial NADH-quinone oxidoreductase (Shimada et al 1998), to generate superoxide. Redox cycling of paraquat results in producing other reactive oxygen species that are highly reactive to cellular macromolecules and/ or oxidation of reducing equivalents, leading to oxidative stress (Bus & Gibson 1984).…”

mentioning

confidence: 99%

Paraquat‐Induced Membrane Dysfunction in Pulmonary Microvascular Endothelial Cells

Tsukamoto

Tampo

Sawada

et al. 2000

Pharmacology & Toxicology

View full text Add to dashboard Cite

Membrane dysfunction monitored by lactate dehydrogenase release from cultured pulmonary microvascular endothelial cells of pigs, which were exposed to paraquat at different concentrations (0.1-2 mM), was examined. Paraquat caused a time-dependent increase in lactate dehydrogenase release. Lactate dehydrogenase releases after 72 hr, 32, 58, and 84% by 0.1, 0.5, and 2 mM paraquat, respectively, were well correlated with cell viability measured by cell adherence. In contrast, reductions of two tetrazolium compounds were depleted profoundly by 72 hr after exposure to 0.5 mM paraquat, suggesting depletion of intracellular reductive substances. Extracellular hydrogen peroxide began to significantly increase 56 hr or 32 hr after exposure to 0.5 mM or 1.5 mM paraquat, respectively, preceding the initial increase of lactate dehydrogenase release (64 hr by 0.5 mM or 48 hr by 1.5 mM). Lactate dehydrogenase release 72 hr after exposure to 0.5 mM paraquat was prevented strongly by catalase (1000 units/ml), but weakly by superoxide dismutase (1000 units/ml). These enzymes failed to restore the reduced acid phosphatase activity. Also, 0.1 mM desferal or a,aø-dipyridyl protected lactate dehydrogenase release. Similarly, 1 mM thiourea or dimethylthiourea, and 0.5 mM a-tocopherol or trolox, were effective, but diethylenetriaminepentaacetic acid (0.1 mM) and probucol (5 or 10 mM) were ineffective. Exposure of 0.5 or 1.5 mM paraquat suppressed levels of lipid peroxidation. These results indicate that membrane dysfunction by paraquat is ascribed to an iron-catalyzed reaction of extracellularly increased hydrogen peroxide. A deleterious species for the membrane dysfunction is discussed.

show abstract

Mitochondrial NADH–Quinone Oxidoreductase of the Outer Membrane Is Responsible for Paraquat Cytotoxicity in Rat Livers

Cited by 86 publications

References 42 publications

Complex I Is the Major Site of Mitochondrial Superoxide Production by Paraquat

Complex I Is the Major Site of Mitochondrial Superoxide Production by Paraquat

Effect of Various Radical Generators on Insulin-Dependent Regulation of Hepatic Gene Expression

Paraquat‐Induced Membrane Dysfunction in Pulmonary Microvascular Endothelial Cells

Contact Info

Product

Resources

About