Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.3.5.1 (succinate dehydrogenase)
 8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The subcellular mechanism of alkenyl halide S-conjugate-induced nephrotoxicity was studied in mitochondria isolated from rat kidney cortex in vitro using the cysteine conjugate of hexachloro-1,3-butadiene, i.e., S-pentachlorobutadienyl-L-cysteine (PCBC) as a model substrate. Respiring mitochondria exposed to various concentrations of PCBC exhibited a dose-dependent loss of ability to retain calcium. This phenomenon was associated with a sudden collapse of the mitochondrial membrane potential. PCBC caused a slow nonenzymatic depletion of mitochondrial glutathione. This was not due to oxidation or formation of mixed disulfides, and was efficiently counteracted by preincubation with aminooxyacetic acid, an inhibitor of cysteine-conjugate beta-lyase activity. PCBC inhibited state 3 respiration in the presence of succinate as substrate, which indicates that the activity of succinate dehydrogenase was affected. Thus, the present data confirm that impairment of mitochondrial function is a feature of nephrotoxicity mediated by alkenyl halide S-conjugates. We suggest a pathway involving interaction of beta-lyase-dependent reactive metabolite with the mitochondrial inner membrane, loss of membrane potential, disturbance of Ca2+ homeostasis, and subsequent respiratory insufficiency as a mechanism for renal tubular cytotoxicity.
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PMID:Toxicity of S-pentachlorobutadienyl-L-cysteine studied with isolated rat renal cortical mitochondria. 367 80

The role of complex II in the cellular protection against oxidative stress was investigated in freshly isolated rat renal proximal tubular cells (PTC) with the use of the nephrotoxin S-(1,2-dichlorovinyl)-L-cysteine (DCVC). DCVC caused oxidative stress in PTC as determined by flow cytometry with dihydrorhodamine-123; this fluorescent probe is readily oxidized by primary hydroperoxides such as those formed during lipid peroxidation. The oxidative stress could be prevented by inhibition of the beta-lyase-mediated formation and covalent binding to cellular macromolecules of reactive DCVC metabolites, with amino oxyacetic acid (AOA), or by the antioxidant N,N'-diphenyl-p-phenylenediamine. Both AOA and DPPD also prevented cell death. The DCVC-induced oxidative stress was associated with a decrease in the succinate:ubiquinone reductase (SQR) activity of complex II, whereas NADH:ubiquinone reductase activity of complex I remained unaffected. AOA prevented the effect on SQR activity, whereas N,N'-diphenyl-p-phenylenediamine did not. Inhibition of SQR activity with thenoyl trifluoracetone (TTFA) potentiated the DCVC-induced oxidative cell injury, suggesting the involvement of SQR activity in an antioxidant pathway. To investigate this in greater detail, PTC were treated with an inhibitor of cytochrome-c-oxidase, KCN, in a buffer containing glycine, which prevents cell death by KCN. Glycine did not affect cell death by DCVC. KCN prevented the DCVC-induced oxidative stress and cell death. KCN cytoprotection could be prevented by inhibition of SQR activity with oxaloacetate or TTFA, whereas inhibition of either complex I or III with rotenone and antimycin, respectively, did not prevent it. The effect of DCVC on complex II was associated with a decrease in the cellular amount of reduced ubiquinone (QH2); the KCN-mediated cytoprotection was related to a 60% increase of cellular QH2. Rotenone almost completely inhibited ubiquinone reduction even in the presence of KCN, whereas oxaloacetate in combination with KCN resulted in QH2 levels comparable to control. This suggests that the SQR activity by complex II rather than the cellular content of reduced ubiquinone (QH2) is important as a part of the cellular antioxidant machinery in the cyto-protection against oxidative stress.
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PMID:Inhibition of succinate:ubiquinone reductase and decrease of ubiquinol in nephrotoxic cysteine S-conjugate-induced oxidative cell injury. 747 24