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Su AL, Harris SM, Elkin ER, Karnovsky A, Colacino J, Loch-Caruso RK. Trichloroethylene Metabolite S-(1,2-Dichlorovinyl)-l-cysteine Stimulates Changes in Energy Metabolites and Amino Acids in the BeWo Human Placental Trophoblast Model during Syncytialization. Chem Res Toxicol 2023; 36:882-899. [PMID: 37162359 PMCID: PMC10499396 DOI: 10.1021/acs.chemrestox.3c00007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Syncytialization, the fusion of cytotrophoblasts into an epithelial barrier that constitutes the maternal-fetal interface, is a crucial event of placentation. This process is characterized by distinct changes to amino acid and energy metabolism. A metabolite of the industrial solvent trichloroethylene (TCE), S-(1,2-dichlorovinyl)-l-cysteine (DCVC), modifies energy metabolism and amino acid abundance in HTR-8/SVneo extravillous trophoblasts. In the current study, we investigated DCVC-induced changes to energy metabolism and amino acids during forskolin-stimulated syncytialization in BeWo cells, a human villous trophoblastic cell line that models syncytialization in vitro. BeWo cells were exposed to forskolin at 100 μM for 48 h to stimulate syncytialization. During syncytialization, BeWo cells were also treated with DCVC at 0 (control), 10, or 20 μM. Following treatment, the targeted metabolomics platform, "Tricarboxylic Acid Plus", was used to identify changes in energy metabolism and amino acids. DCVC treatment during syncytialization decreased oleic acid, aspartate, proline, uridine diphosphate (UDP), UDP-d-glucose, uridine monophosphate, and cytidine monophosphate relative to forskolin-only treatment controls, but did not increase any measured metabolite. Notable changes stimulated by syncytialization in the absence of DCVC included increased adenosine monophosphate and guanosine monophosphate, as well as decreased aspartate and glutamate. Pathway analysis revealed multiple pathways in amino acid and sugar metabolisms that were altered with forskolin-stimulated syncytialization alone and DCVC treatment during syncytialization. Analysis of ratios of metabolites within the pathways revealed that DCVC exposure during syncytialization changed metabolite ratios in the same or different direction compared to syncytialization alone. Building off our oleic acid findings, we found that extracellular matrix metalloproteinase-2, which is downstream in oleic acid signaling, underwent the same changes as oleic acid. Together, the metabolic changes stimulated by DCVC treatment during syncytialization suggest changes in energy metabolism and amino acid abundance as potential mechanisms by which DCVC could impact syncytialization and pregnancy.
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Affiliation(s)
- Anthony L. Su
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
| | - Sean M. Harris
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
| | - Elana R. Elkin
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
| | - Alla Karnovsky
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Justin Colacino
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
- Department of Nutritional Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Rita Karen Loch-Caruso
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109
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Mally A, Jarzina S. Mapping Adverse Outcome Pathways for Kidney Injury as a Basis for the Development of Mechanism-Based Animal-Sparing Approaches to Assessment of Nephrotoxicity. FRONTIERS IN TOXICOLOGY 2022; 4:863643. [PMID: 35785263 PMCID: PMC9242087 DOI: 10.3389/ftox.2022.863643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/11/2022] [Indexed: 02/04/2023] Open
Abstract
In line with recent OECD activities on the use of AOPs in developing Integrated Approaches to Testing and Assessment (IATAs), it is expected that systematic mapping of AOPs leading to systemic toxicity may provide a mechanistic framework for the development and implementation of mechanism-based in vitro endpoints. These may form part of an integrated testing strategy to reduce the need for repeated dose toxicity studies. Focusing on kidney and in particular the proximal tubule epithelium as a key target site of chemical-induced injury, the overall aim of this work is to contribute to building a network of AOPs leading to nephrotoxicity. Current mechanistic understanding of kidney injury initiated by 1) inhibition of mitochondrial DNA polymerase γ (mtDNA Polγ), 2) receptor mediated endocytosis and lysosomal overload, and 3) covalent protein binding, which all present fairly well established, common mechanisms by which certain chemicals or drugs may cause nephrotoxicity, is presented and systematically captured in a formal description of AOPs in line with the OECD AOP development programme and in accordance with the harmonized terminology provided by the Collaborative Adverse Outcome Pathway Wiki. The relative level of confidence in the established AOPs is assessed based on evolved Bradford-Hill weight of evidence considerations of biological plausibility, essentiality and empirical support (temporal and dose-response concordance).
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Diverse Roles of Mitochondria in Renal Injury from Environmental Toxicants and Therapeutic Drugs. Int J Mol Sci 2021; 22:ijms22084172. [PMID: 33920653 PMCID: PMC8073222 DOI: 10.3390/ijms22084172] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/05/2021] [Accepted: 04/14/2021] [Indexed: 01/19/2023] Open
Abstract
Mitochondria are well-known to function as the primary sites of ATP synthesis in most mammalian cells, including the renal proximal tubule. Other functions have also been associated with different mitochondrial activities, including the regulation of redox status and the initiation of mitophagy and apoptosis. Mechanisms for the membrane transport of glutathione (GSH) and various GSH-derived metabolites across the mitochondrial inner membrane of renal proximal tubular cells are critical determinants of these functions and may serve as pharmacological targets for potential therapeutic approaches. Specific interactions of reactive intermediates, derived from drug metabolism, with molecular components in mitochondria have been identified as early steps in diverse forms of chemically-induced nephrotoxicity. Applying this key observation, we developed a novel hypothesis regarding the identification of early, sensitive, and specific biomarkers of exposure to nephrotoxicants. The underlying concept is that upon exposure to a diverse array of environmental contaminants, as well as therapeutic drugs whose efficacy is limited by nephrotoxicity, renal mitochondria will release both high- and low-molecular-weight components into the urine or the extracellular medium in an in vitro model. The detection of these components may then serve as indicators of exposure before irreversible renal injury has occurred.
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Elkin ER, Bridges D, Harris SM, Loch-Caruso RK. Exposure to Trichloroethylene Metabolite S-(1,2-Dichlorovinyl)-L-cysteine Causes Compensatory Changes to Macronutrient Utilization and Energy Metabolism in Placental HTR-8/SVneo Cells. Chem Res Toxicol 2020; 33:1339-1355. [PMID: 31951115 PMCID: PMC7299793 DOI: 10.1021/acs.chemrestox.9b00356] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
![]()
Trichloroethylene
(TCE) is a widespread environmental contaminant
following decades of use as an industrial solvent, improper disposal,
and remediation challenges. Consequently, TCE exposure continues to
constitute a risk to human health. Despite epidemiological evidence
associating exposure with adverse birth outcomes, the effects of TCE
and its metabolite S-(1, 2-dichlorovinyl)-L-cysteine
(DCVC) on the placenta remain undetermined. Flexible and efficient
macronutrient and energy metabolism pathway utilization is essential
for placental cell physiological adaptability. Because DCVC is known
to compromise cellular energy status and disrupt energy metabolism
in renal proximal tubular cells, this study investigated the effects
of DCVC on cellular energy status and energy metabolism pathways in
placental cells. Human extravillous trophoblast cells, HTR-8/SVneo,
were exposed to 5–20 μM DCVC for 6 or 12 h. After establishing
concentration and exposure duration thresholds for DCVC-induced cytotoxicity,
targeted metabolomics was used to evaluate overall energy status and
metabolite concentrations from energy metabolism pathways. The data
revealed glucose metabolism perturbations including a time-dependent
accumulation of glucose-6-phosphate+frutose-6-phosphate (G6P+F6P)
as well as independent shunting of glucose intermediates that diminished
with time, with modest energy status decline but in the absence of
significant changes in ATP concentrations. Furthermore, metabolic
profiling suggested that DCVC stimulated compensatory utilization
of glycerol, lipid, and amino acid metabolism to provide intermediate
substrates entering downstream in the glycolytic pathway or the tricarboxylic
acid cycle. Lastly, amino acid deprivation increased susceptibility
to DCVC-induced cytotoxicity. Taken together, these results suggest
that DCVC caused metabolic perturbations necessitating adaptations
in macronutrient and energy metabolism pathway utilization to maintain
adequate ATP levels.
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Affiliation(s)
- Elana R Elkin
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109-2029, United States
| | - Dave Bridges
- Department of Nutritional Sciences, University of Michigan, Ann Arbor, Michigan 48109-2029, United States
| | - Sean M Harris
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109-2029, United States
| | - Rita Karen Loch-Caruso
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109-2029, United States
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Yaqoob N, Evans A, Foster JR, Lock EA. Trichloroethylene and trichloroethanol-induced formic aciduria and renal injury in male F-344 rats following 12 weeks exposure. Toxicology 2014; 323:70-7. [DOI: 10.1016/j.tox.2014.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 06/03/2014] [Accepted: 06/06/2014] [Indexed: 11/30/2022]
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Anders M. Exploiting endobiotic metabolic pathways to target xenobiotic antioxidants to mitochondria. Mitochondrion 2013; 13:454-63. [DOI: 10.1016/j.mito.2012.10.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 08/17/2012] [Accepted: 10/23/2012] [Indexed: 02/04/2023]
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Irving RM, Elfarra AA. Role of reactive metabolites in the circulation in extrahepatic toxicity. Expert Opin Drug Metab Toxicol 2012; 8:1157-72. [PMID: 22681489 DOI: 10.1517/17425255.2012.695347] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
INTRODUCTION Reactive metabolite-mediated toxicity is frequently limited to the organ where the electrophilic metabolites are generated. Some reactive metabolites, however, might have the ability to translocate from their site of formation. This suggests that for these reactive metabolites, investigations into the role of organs other than the one directly affected could be relevant to understanding the mechanism of toxicity. AREAS COVERED The authors discuss the physiological and biochemical factors that can enable reactive metabolites to cause toxicity in an organ distal from the site of generation. Furthermore, the authors present a case study which describes studies that demonstrate that S-(1,2-dichlorovinyl)-L-cysteine sulfoxide (DCVCS) and N-acetyl-S-(1,2-dichlorovinyl-L-cysteine sulfoxide (N-AcDCVCS), reactive metabolites of the known trichloroethylene metabolites S-(1,2-dichlorovinyl)-L-cysteine (DCVC), and N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine (N-AcDCVC), are generated in the liver and translocate through the circulation to the kidney to cause nephrotoxicity. EXPERT OPINION The ability of reactive metabolites to translocate could be important to consider when investigating mechanisms of toxicity. A mechanistic approach, similar to the one described for DCVCS and N-AcDCVCS, could be useful in determining the role of circulating reactive metabolites in extrahepatic toxicity of drugs and other chemicals. If this is the case, intervention strategies that would not otherwise be feasible might be effective for reducing extrahepatic toxicity.
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Affiliation(s)
- Roy M Irving
- University of Wisconsin-Madison, School of Veterinary Medicine, Department of Comparative Biosciences and Molecular and Environmental Toxicology Center, Madison, WI 53706, USA
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Irving RM, Brownfield MS, Elfarra AA. N-biotinyl-S-(1,2-dichlorovinyl)-L-cysteine sulfoxide as a potential model for S-(1,2-dichlorovinyl)-L-cysteine sulfoxide: characterization of stability and reactivity with glutathione and kidney proteins in vitro. Chem Res Toxicol 2011; 24:1915-23. [PMID: 21988407 DOI: 10.1021/tx200263n] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
S-(1,2-Dichlorovinyl)-L-cysteine sulfoxide (DCVCS) is a reactive and potent nephrotoxic metabolite of the human trichloroethylene metabolite S-(1,2-dichlorovinyl)-L-cysteine (DCVC). Because DCVCS covalent binding to kidney proteins likely plays a role in its nephrotoxicity, in this study biotin-tagged DCVCS, N-biotinyl-DCVCS (NB-DCVCS), was synthesized, and its stability in buffer alone and in the presence of rat blood or plasma was characterized in vitro. In addition, reactivity toward GSH and covalent binding to selected model enzymes and isolated kidney proteins were characterized. The half-lives of NB-DCVCS (39.6 min) and the DCVCS (diastereomer 1, 14.4 min; diastereomer 2, 6 min) in the presence of GSH were comparable. Incubating the model enzymes glutathione reductase and malate dehydrogenase with 10 μM NB-DCVCS for 3 h at 37 °C followed by immunoblotting using antibiotin antibodies demonstrated that glutathione reductase and malate dehydrogenase were extensively modified by NB-DCVCS. When rat kidney cytosol (6 μg/μL) was incubated with NB-DCVCS (312.5 nM to 5 μM) for 3 h at 37 °C followed by immunoblotting, a concentration-dependent increase in signal with multiple proteins with different molecular weights was observed, suggesting that NB-DCVCS binds to multiple kidney proteins with different selectivity. Incubating rat kidney cytosol with DCVCS (10-100 μM) prior to the addition of NB-DCVCS (2.5 μM) reduced the immunoblotting signal, suggesting that NB-DCVCS and DCVCS compete for the same binding sites. A comparison of the stability of NB-DCVCS and DCVCS in rat blood and plasma was determined in vitro, and NB-DCVCS exhibited higher stability than DCVCS in both media. Collectively, these results suggest that NB-DCVCS shows sufficient stability, reactivity, and selectivity to warrant further investigations into its possible use as a tool for future characterization of the role of covalent modification of renal proteins by DCVCS in nephrotoxicity.
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Affiliation(s)
- Roy M Irving
- Molecular and Environmental Toxicology Center, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Putting bioactivation reactions to work: Targeting antioxidants to mitochondria. Chem Biol Interact 2011; 192:8-13. [DOI: 10.1016/j.cbi.2010.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 10/08/2010] [Accepted: 10/14/2010] [Indexed: 01/01/2023]
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Cooper AJL, Bruschi SA, Iriarte A, Martinez-Carrion M. Mitochondrial aspartate aminotransferase catalyses cysteine S-conjugate beta-lyase reactions. Biochem J 2002; 368:253-61. [PMID: 12137566 PMCID: PMC1222959 DOI: 10.1042/bj20020531] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2002] [Revised: 07/19/2002] [Accepted: 07/23/2002] [Indexed: 11/17/2022]
Abstract
Rat liver mitochondrial aspartate aminotransferase (a homodimer) was shown to catalyse a beta-lyase reaction with three nephrotoxic halogenated cysteine S-conjugates [ S -(1,1,2,2-tetrafluoroethyl)-L-cysteine, S -(1,2-dichlorovinyl)-L-cysteine and S -(2-chloro-1,1,2-trifluoroethyl)-L-cysteine], and less effectively so with a non-toxic cysteine S-conjugate [benzothiazolyl-L-cysteine]. Transamination competes with the beta-lyase reaction, but is not favourable. The ratio of beta elimination to transamination in the presence of S -(1,1,2,2-tetrafluoroethyl)-L-cysteine and 2-oxoglutarate is >100. Syncatalytic inactivation by the halogenated cysteine S-conjugates is also observed. The enzyme turns over approx. 2700 molecules of halogenated cysteine S-conjugate on average for every monomer inactivated. Kidney mitochondria are known to be especially sensitive to toxic halogenated cysteine S-conjugates. Evidence is presented that 15-20% of the cysteine S-conjugate beta-lyase activity towards S -(1,1,2,2-tetrafluoroethyl)-L-cysteine in crude kidney mitochondrial homogenates is due to mitochondrial aspartate aminotransferase. The possible involvement of mitochondrial aspartate aminotransferase in the toxicity of halogenated cysteine S-conjugates is also discussed.
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Affiliation(s)
- Arthur J L Cooper
- Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10021, USA.
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Cooper AJL, Bruschi SA, Anders MW. Toxic, halogenated cysteine S-conjugates and targeting of mitochondrial enzymes of energy metabolism. Biochem Pharmacol 2002; 64:553-64. [PMID: 12167474 DOI: 10.1016/s0006-2952(02)01076-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Several haloalkenes are metabolized in part to nephrotoxic cysteine S-conjugates; for example, trichloroethylene and tetrafluoroethylene are converted to S-(1,2-dichlorovinyl)-L-cysteine (DCVC) and S-(1,1,2,2-tetrafluoroethyl)-L-cysteine (TFEC), respectively. Although DCVC-induced toxicity has been investigated since the 1950s, the toxicity of TFEC and other haloalkene-derived cysteine S-conjugates has been studied more recently. Some segments of the US population are exposed to haloalkenes either through drinking water or in the workplace. Therefore, it is important to define the toxicological consequences of such exposures. Most halogenated cysteine S-conjugates are metabolized by cysteine S-conjugate beta-lyases to pyruvate, ammonia, and an alpha-chloroenethiolate (with DCVC) or an alpha-difluoroalkylthiolate (with TFEC) that may eliminate halide to give a thioacyl halide, which reacts with epsilon-amino groups of lysine residues in proteins. Nine mammalian pyridoxal 5'-phosphate (PLP)-containing enzymes catalyze cysteine S-conjugate beta-lyase reactions, including mitochondrial aspartate aminotransferase (mitAspAT), and mitochondrial branched-chain amino acid aminotransferase (BCAT(m)). Most of the cysteine S-conjugate beta-lyases are syncatalytically inactivated. TFEC-induced toxicity is associated with covalent modification of several mitochondrial enzymes of energy metabolism. Interestingly, the alpha-ketoglutarate- and branched-chain alpha-keto acid dehydrogenase complexes (KGDHC and BCDHC), but not the pyruvate dehydrogenase complex (PDHC), are susceptible to inactivation. mitAspAT and BCAT(m) may form metabolons with KGDHC and BCDHC, respectively, but no PLP enzyme is known to associate with PDHC. Consequently, we hypothesize that not only do these metabolons facilitate substrate channeling, but they also facilitate toxicant channeling, thereby promoting the inactivation of proximate mitochondrial enzymes and the induction of mitochondrial dysfunction.
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Affiliation(s)
- Arthur J L Cooper
- Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10021, USA.
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Cooper AJ, Wang J, Gartner CA, Bruschi SA. Co-purification of mitochondrial HSP70 and mature protein disulfide isomerase with a functional rat kidney high-M(r) cysteine S-conjugate beta-lyase. Biochem Pharmacol 2001; 62:1345-53. [PMID: 11709194 DOI: 10.1016/s0006-2952(01)00802-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
S-(1,1,2,2-Tetrafluoroethyl)-L-cysteine (TFEC, the cysteine S-conjugate of tetrafluoroethylene) is an example of a nephrotoxic, halogenated cysteine S-conjugate. Toxicity results in part from the cysteine S-conjugate beta-lyase(s)-catalyzed conversion of TFEC to a thioacylating fragment with the associated production of pyruvate and ammonia. In the present study, we have demonstrated that rat kidney homogenates contain at least three enzyme fractions that are capable of catalyzing a cysteine S-conjugate beta-lyase reaction with TFEC. One of these fractions contains a high-M(r) lyase. At least two proteins co-purify with this high-M(r) complex. N-Terminal analysis (15 cycles) revealed that the smaller species was mature protein disulfide isomerase (M(r) approximately 54,200) from which the 24 amino acid endoplasmic reticulum signal peptide had been removed. Internal amino acid sequencing (15 cycles) revealed that the larger species was mitochondrial HSP70 (mtHSP70; M(r) approximately 75,000). The present findings offer an explanation for the previous observation that mtHSP70 in kidney mitochondria is heavily thioacylated when rats are injected with TFEC (Bruschi et al., J Biol Chem 1993;268:23157-61).
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Affiliation(s)
- A J Cooper
- Department of Biochemistry, Weill Medical College of Cornell University, New York, NY, USA.
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Park LC, Gibson GE, Bunik V, Cooper AJ. Inhibition of select mitochondrial enzymes in PC12 cells exposed to S-(1,1,2,2-tetrafluoroethyl)-L-cysteine. Biochem Pharmacol 1999; 58:1557-65. [PMID: 10535746 DOI: 10.1016/s0006-2952(99)00247-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Many halogenated foreign compounds are detoxified by conversion to the corresponding cysteine S-conjugate, which is N-acetylated and excreted. However, several halogenated cysteine S-conjugates [e.g. S-(1,1,2,2-tetrafluoroethy)-L-cysteine (TFEC)] are converted to mitochondrial toxicants by cysteine S-conjugate beta-lyases. In the present work, we showed that TFEC appreciably inactivated highly purified alpha-ketoglutarate dehydrogenase complex (KGDHC) in the presence of a cysteine S-conjugate beta-lyase. Incubation of PC12 cells (which contain endogenous cysteine S-conjugate beta-lyase activity) with TFEC led to a concentration- and time-dependent loss of endogenous KGDHC activity. A 24-hr exposure to 1 mM TFEC decreased KGDHC activity in the cells by 90%. Although treatment with TFEC did not inhibit intrinsic pyruvate dehydrogenase complex (PDHC) activity, it inhibited dichloroacetate/Mg2+-mediated activation/dephosphorylation of PDHC in the PC12 cells by 90%. To determine the selectivity of enzymes targeted by TFEC, several cytosolic and mitochondrial enzymes involved in energy metabolism [malate dehydrogenase, glyceraldehyde 3-phosphate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, cytosolic and mitochondrial aspartate aminotransferases (AspAT)] were also assayed in the PC12 cells exposed to 1 mM TFEC for 24 hr. Of these enzymes, only mitochondrial AspAT, a key enzyme of the malate-aspartate shuttle, was inhibited. The present results demonstrate a selective vulnerability of mitochondrial enzymes to toxic cysteine S-conjugates. The data indicate that TFEC may be a useful cellular/mitochondrial toxicant for elucidating the consequences of the diminished mitochondrial function that accompanies numerous neurodegenerative diseases.
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Affiliation(s)
- L C Park
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY, USA
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Bruschi SA, Lindsay JG, Crabb JW. Mitochondrial stress protein recognition of inactivated dehydrogenases during mammalian cell death. Proc Natl Acad Sci U S A 1998; 95:13413-8. [PMID: 9811814 PMCID: PMC24833 DOI: 10.1073/pnas.95.23.13413] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The mammalian renal toxicant tetrafluoroethylcysteine (TFEC) is metabolized to a reactive intermediate that covalently modifies the lysine residues of a select group of mitochondrial proteins, forming difluorothioamidyl lysine protein adducts. Cellular damage is initiated by this process and cell death ensues. NH2-terminal sequence analysis of purified mitochondrial proteins containing difluorothioamidyl lysine adducts identified the lipoamide succinyltransferase and dihydrolipoamide dehydrogenase subunits of the alpha-ketoglutarate dehydrogenase complex (alphaKGDH), a key regulatory component of oxidative metabolism, as targets for TFEC action. Adduct formation resulted in marked inhibition of alphaKGDH enzymatic activity, whereas the related pyruvate dehydrogenase complex was unmodified by TFEC and its activity was not inhibited in vivo. Covalent modification of alphaKGDH subunits also resulted in interactions with mitochondrial chaperonin HSP60 in vivo and with HSP60 and mitochondrial HSP70 in vitro. These observations confirm the role of mammalian stress proteins in the recognition of abnormal proteins and provide supporting evidence for reactive metabolite-induced cell death by modification of critical protein targets.
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Affiliation(s)
- S A Bruschi
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195-7610, USA.
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Cooper AJ. Mechanisms of cysteine S-conjugate beta-lyases. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 1998; 72:199-238. [PMID: 9559054 DOI: 10.1002/9780470123188.ch6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mercapturic acids are conjugates of S-(N-acetyl)-L-cysteine formed during the detoxification of xenobiotics and during the metabolism of such endogenous agents as estrogens and leukotrienes. Many mercaturates are formed from the corresponding glutathione S-conjugates. This chapter focuses on (a) the discovery of the cysteine S-conjugate beta-lyases; (b) the involvement of pyridoxal-5-phosphate; (c) the influence of the electron-withdrawing properties of the group attached to the sulfur atom; and (d) the potential of cysteine S-conjugates as pro-drugs.
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Affiliation(s)
- A J Cooper
- Department of Biochemistry, Cornell University Medical College, New York 10021, USA
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Skrede S, Sørensen HN, Larsen LN, Steineger HH, Høvik K, Spydevold OS, Horn R, Bremer J. Thia fatty acids, metabolism and metabolic effects. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1344:115-31. [PMID: 9030189 DOI: 10.1016/s0005-2760(96)00138-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
(1) The chemical properties of thia fatty acids are similar to normal fatty acids, but their metabolism (see below: points 2-6) and metabolic effects (see below: points 7-15) differ greatly from these and are dependent upon the position of the sulfur atom. (2) Long-chain thia fatty acids and alkylthioacrylic acids are activated to their CoA esters in endoplasmatic reticulum. (3) 3-Thia fatty acids cannot be beta-oxidized. They are metabolized by extramitochondrial omega-oxidation and sulfur oxidation in the endoplasmatic reticulum followed by peroxisomal beta-oxidation to short sulfoxy dicarboxylic acids. (4) 4-Thia fatty acids are beta-oxidized mainly in mitochondria to alkylthioacryloyl-CoA esters which accumulate and are slowly converted to 2-hydroxy-4-thia acyl-CoA which splits spontaneously to an alkylthiol and malonic acid semialdehyde-CoA ester. The latter presumably is hydrolyzed and metabolized to acetyl-CoA and CO2. (5) Both 3- and 4-thiastearic acid are desaturated to the corresponding thia oleic acids. (6) Long-chain 3- and 4-thia fatty acids are incorporated into phospholipids in vivo, particularly in heart, and in hepatocytes and other cells in culture. (7) Long-chain 3-thia fatty acids change the fatty acid composition of the phospholipids: in heart, the content of n-3 fatty acids increases and n-6 fatty acids decreases. (8) 3-Thia fatty acids increase fatty acid oxidation in liver through inhibition of malonyl-CoA synthesis, activation of CPT I, and induction of CPT-II and enzymes of peroxisomal beta-oxidation. Activation of fatty acid oxidation is the key to the hypolipidemic effect of 3-thia fatty acids. Also other lipid metabolizing enzymes are induced. (9) Fatty acid- and cholesterol synthesis is inhibited in hepatocytes. (10) The nuclear receptors PPAR alpha and RXR alpha are induced by 3-thia fatty acids. (11) The induction of enzymes and of PPAR alpha and RXR alpha are increased by dexamethasone and counteracted by insulin. (12) 4-Thia fatty acids inhibit fatty acid oxidation and induce fatty liver in vivo. The inhibition presumably is explained by accumulation of alkylthioacryloyl-CoA in the mitochondria. This metabolite is a strong inhibitor of CPT-II. (13) Alkylthioacrylic acids inhibits both fatty acid oxidation and esterification. Inhibition of esterification presumably follows accumulation of extramitochondrial alkylthioacryloyl-CoA, an inhibitor of microsomal glycerophosphate acyltransferase. (14) 9-Thia stearate is a strong inhibitor of the delta 9-desaturase in liver and 10-thia stearate of dihydrosterculic acid synthesis in trypanosomes. (15) Some attempts to develop thia fatty acids as drugs are also reviewed.
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Affiliation(s)
- S Skrede
- Institute of Medical Biochemistry, University of Oslo, Norway
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17
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Adcock HJ, Gaskin PJ, Shaw PN, Teesdale-Spittle PH, Buckberry LD. Novel sources of mammalian C-S lyase activity. J Pharm Pharmacol 1996; 48:150-3. [PMID: 8935163 DOI: 10.1111/j.2042-7158.1996.tb07114.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The C-S lysis of L-cysteine conjugates is one biotransformation pathway which is responsible for the generation of mutagenic and cytotoxic metabolic species. Thirteen cysteine S-conjugates were synthesized in our laboratories and incubated with aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) enzymes from porcine heart tissue. The C-S lyase (CSL) activity for each enzyme-substrate combination was determined. ASAT and ALAT were shown to exhibit CSL activity and it was also demonstrated that this activity was inhibited in the presence of the pyridoxal phosphate-dependent enzyme inhibitor amino(oxyacetic acid) confirming the pyridoxal phosphate-dependent mechanism by which C-S lysis is known to take place. This finding has potentially important implications for the risk assessment of compounds which produce L-cysteine conjugates during their biotransformation.
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Affiliation(s)
- H J Adcock
- Department of Chemistry, De Montfort University, Leicester, UK
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18
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Anders MW. Mitochondrial bioactivation of cysteine S-conjugates and 4-thiaalkanoates: implications for mitochondrial dysfunction and mitochondrial diseases. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1271:51-7. [PMID: 7599225 DOI: 10.1016/0925-4439(95)00009-s] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The toxicity of most drugs and chemicals is associated with their enzymatic conversion to toxic metabolites. Bioactivation reactions occur in a range of organs and organelles, including mitochondria. The toxicity of haloalkene-derived cysteine S-conjugates and related 4-thiaalkanoates is associated with their mitochondrial bioactivation. Toxic cysteine S-conjugates are formed by the glutathione S-transferase-catalyzed addition of glutathione to haloalkenes to give glutathione S-conjugates, which are hydrolyzed by gamma-glutamyltransferase and dipeptidases. Mitochondrial cysteine conjugate beta-lyase-catalyzed bioactivation of cysteine S-conjugates affords unstable alpha-halothiolates. Haloalkene-derived 4-thiaalkanoates, which are analogs of cysteine S-conjugates that lack an alpha-amino group, undergo bioactivation by the enzymes of fatty acid beta-oxidation to give 3-hydroxy-4-thiaalkanoates that eliminate alpha-halothiolates. alpha-Halothiolates yield alkylating and acylating agents that interact with cellular macromolecules and thereby cause cell damage. Mitochondrial dysfunction is the hallmark of cysteine S-conjugate-induced cytotoxicity: decreased respiration, decreased ATP and total adenine nucleotide concentrations, depletion of the mitochondrial glutathione content, perturbations in cellular Ca2+ homeostasis, and damage to the mitochondrial genome are seen with cysteine S-conjugates. Similar changes are observed with cytotoxic 4-thiaalkanoates, but inhibition of the medium-chain acyl-CoA dehydrogenase and hypoglycemia are also observed.
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Affiliation(s)
- M W Anders
- Department of Pharmacology, University of Rochester, New York 14642, USA
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19
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Gaskin PJ, Adcock HJ, Buckberry LD, Teesdale-Spittle PH, Shaw PN. The C-S lysis of L-cysteine conjugates by aspartate and alanine aminotransferase enzymes. Hum Exp Toxicol 1995; 14:422-7. [PMID: 7612304 DOI: 10.1177/096032719501400506] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
One biotransformation pathway which is responsible for the generation of mutagenic and cytotoxic metabolites is that of the C-S lysis (CSL) of L-cysteine conjugates. Thirteen cysteine S-conjugates, synthesised in our laboratories, were incubated with porcine heart aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT), and the C-S lyase activity for each enzyme-substrate combination was determined. ASAT and ALAT were shown to exhibit CSL activity. It was also demonstrated that this activity was inhibited in the presence of the pyridoxal phosphate (PLP)-dependent enzyme inhibitor amino(oxyacetic acid) (AOAA) confirming the pyridoxal phosphate dependent mechanism by which C-S lysis is known to take place. Since the activities of these enzymes are used as biomarkers for the assessment of organ damage, the potential interaction of L-cysteine conjugates with them may suppress their activity through direct inhibition.
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Affiliation(s)
- P J Gaskin
- Department of Pharmaceutical Sciences, University of Nottingham, UK
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20
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Koechel DA, Krejci ME, Bretz NS. 4-Maleimidohippuric acid--a tailor-made, direct, site-specific nephrotoxin: effects on renal function and ultrastructure in pentobarbital-anesthetized dogs. Toxicology 1995; 96:115-26. [PMID: 7886682 DOI: 10.1016/0300-483x(94)02916-i] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A model has been proposed to explain at least one of the possible pathways through which a xenobiotic might produce proximal tubule necrosis. The model is formulated on the idea that a compound must possess two structural features: (i) a carboxyl or amino acid moiety that would allow for selective uptake into proximal tubule cells via the strategically located antiluminal membrane-bound organic anion transport system or the luminal membrane-bound amino acid transport system(s), respectively, and (ii) a highly reactive moiety that can directly alkylate proximal tubular components, or a moiety that can be biotransformed within proximal tubular cells to such a substance. In an attempt to validate the proposed structural features as prerequisites for xenobiotic induction of proximal tubular necrosis, a novel compound, 4-maleimidohippuric acid (4-MHA), was synthesized which possesses an anionic group and a reactive moiety. Following the administration of 4-MHA directly into the renal artery of pentobarbital-anesthetized dogs, specific unilateral ultrastructural damage was noted only in the S1 and S2 cell types of the proximal tubule; the most notable renal function changes included proteinuria and glucosuria. Anionic, but non-alkylating, relatives of 4-MHA failed to alter renal function or ultrastructure. The specific proximal tubular toxicity of 4-MHA validates the proposed structural requirements for induction of proximal tubular necrosis.
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Affiliation(s)
- D A Koechel
- Department of Pharmacology, Medical College of Ohio, Toledo 43699-0008
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21
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Buckberry LD, Adcock HJ, Adler J, Blagbrough IS, Gaskin PJ, Shaw PN. In VitroMethods for the Assessment of L-Cysteine Conjugate Toxicity. Altern Lab Anim 1994. [DOI: 10.1177/026119299402200203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
L-Cysteine conjugates are normally metabolised via N-acetylation to produce a mercapturic acid. However, a recently identified metabolic route (C-S lysis) may lead to the generation of an unstable thiol which has been demonstrated to be responsible for toxicity in various mammalian species.Human Chang liver cells were challenged with a number of established L-cysteine conjugates. The cellular toxicity of these compounds was determined using a range of assay procedures, which provided differing information, depending on the assay method used. These observations were then investigated in order to establish which system would provide the most reliable indication of C-S lyase toxicity and whether any information on the mechanism of action could be obtained by these assay methods.
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Affiliation(s)
- Lorraine D. Buckberry
- Department of Pharmaceutical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Harriet J. Adcock
- Department of Pharmaceutical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Jeremy Adler
- Department of Pharmaceutical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Ian S. Blagbrough
- Department of Pharmaceutical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Peter J. Gaskin
- Department of Pharmaceutical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - P. Nicholas Shaw
- Department of Pharmaceutical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
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22
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23
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Koechel DA, Krejci ME, Ridgewell RE. S-(1,2-dichlorovinyl)-3-mercaptopropionic acid effects on renal function and ultrastructure in pentobarbital-anesthetized dogs: site-specific toxicity and evidence for its toxification via the pathway responsible for beta-oxidation of fatty acids. Toxicology 1993; 85:1-24. [PMID: 8291067 DOI: 10.1016/0300-483x(93)90080-c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
S-(1,2-dichlorovinyl)-3-mercaptopropionic acid (DCV-3-MPA) was equally nephrotoxic to spontaneously-respiring and mechanically-ventilated, pentobarbital-anesthetized dogs. Its nephrotoxicity was expressed as dose-dependent changes in key renal function parameters, in proximal tubular S1, S2 and S3 cellular architecture and in the ability of the kidneys to respond maximally to ethacrynic acid, an efficacious loop diuretic. The nephrotoxicity associated with DCV-3-MPA was not the result of extrarenal actions such as hypoxemia and subsequent renal tissue hypoxia because mechanical ventilation was not protective. Four lines of evidence suggested that DCV-3-MPA was taken-up by renal proximal tubular cells like a fatty acid and metabolized by the mitochondrial beta-oxidation pathway to a reactive nephrotoxic intermediate: (i) probenecid pretreatment, which reduces the renal uptake of many organic anions but fails to do so with anions of fatty acids, failed to modify the nephrotoxicity of DCV-3-MPA; (ii) the next higher and lower homologues of DCV-3-MPA (i.e., S-(1,2-dichlorovinyl)-4-mercaptobutanoic acid (DCV-4-MBA) and S-(1,2-dichlorovinyl)-mercaptoacetic acid (DCV-MAA)) cannot yield the same reactive intermediate as DCV-3-MPA upon beta-oxidation and neither was nephrotoxic; (iii) DCV-MAA was found in plasma and urine following administration of DCV-4-MBA and (iv) the renal mitochondria were reproducibly damaged by DCV-3-MPA whereas the peroxisomes, which are also capable of performing beta-oxidation of certain fatty acids, were unscathed.
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Affiliation(s)
- D A Koechel
- Department of Pharmacology, Medical College of Ohio, Toledo 43699-0008
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24
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Buckberry LD, Blagbrough IS, Shaw PN. Cysteine conjugate toxicity in a human cell line: correlation with C-S lyase activity in human hepatic tissue. Hum Exp Toxicol 1993; 12:329-35. [PMID: 8104012 DOI: 10.1177/096032719301200412] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
C-S lyase enzymes catalyse the generation of mutagenic and/or cytotoxic thiols from cysteine conjugated xenobiotics. These cysteine conjugates are produced subsequent to glutathione conjugations as a metabolic step in the mercapturic acid pathway, traditionally thought of as a pathway solely associated with detoxification. Human Chang liver (HCL) cells were challenged with a range of cysteine conjugates demonstrated to be substrates for human hepatic C-S lyases. The cellular toxicity of these compounds was determined and it was observed that the rank order of substrate toxicity obtained for the HCL cells followed the rank order of C-S lyase activity of the substrates in a freshly isolated mitochondrial fraction of human tissue. The presence of C-S lyase activity was also established in this cell line.
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Affiliation(s)
- L D Buckberry
- Department of Pharmaceutical Sciences, University of Nottingham, UK
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25
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Harris JW, Fitzsimmons ME, Anders MW. Synthesis of [2-3H-ethyl]S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine and its use in covalent-binding studies. Anal Biochem 1992; 204:300-4. [PMID: 1443527 DOI: 10.1016/0003-2697(92)90242-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Metabolism of S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine (CTFC) yields chlorofluorothioacetyl fluoride, which reacts with cellular proteins to form stable lysine adducts. Little is known about the subcellular localization of these protein adducts or about their role in CTFC-induced nephrotoxicity. A method for the synthesis of CTFC and other cysteine S-conjugates labeled with 3H at the S-alkyl or S-alkenyl position would be useful in studies of S-conjugate metabolism and toxicity. Reaction of L-cysteine, chlorotrifluoroethene, 1,8-diazabicyclo[5.4.0]undec-7-ene, and 3H-labeled water followed by repeated crystallization yielded radiochemically pure [3H]CTFC (235 mg, 20% yield; sp act 1.07 x 10(9) Bq/mmol), which was identical to CTFC by TLC, 1H NMR, and 19F NMR. 3H NMR revealed a doublet of triplets at 6.5 ppm with geminal and vicinal T-F couplings of 51.5 and 6.0 Hz, respectively, consistent with the proposed structure. When 2H-labeled water was used, [2H]CTFC was formed, and its structure was confirmed by 1H and 19F NMR, FAB-MS, and TLC. Analysis of renal and hepatic subcellular fractions of rats given 1, 10, or 100 mumol/kg [3H]CTFC showed a dose-dependent binding of 3H-containing metabolites to liver and kidney proteins.
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Affiliation(s)
- J W Harris
- Department of Pharmacology, University of Rochester School of Medicine & Dentistry, New York 14642
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26
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Hargus SJ, Anders MW. Immunochemical detection of covalently modified kidney proteins in S-(1,1,2,2-tetrafluoroethyl)-L-cysteine-treated rats. Biochem Pharmacol 1991; 42:R17-20. [PMID: 1741763 DOI: 10.1016/0006-2952(91)90580-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- S J Hargus
- Department of Pharmacology, University of Rochester, NY 14642
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27
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Hayden P, Ichimura T, McCann D, Pohl L, Stevens J. Detection of cysteine conjugate metabolite adduct formation with specific mitochondrial proteins using antibodies raised against halothane metabolite adducts. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)55074-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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28
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Fitzsimmons ME, Anders MW. Fatty acid beta-oxidation-dependent bioactivation of 5,6-dichloro-4-thia-5-hexenoate and analogs in isolated rat hepatocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1991; 283:281-4. [PMID: 2068997 DOI: 10.1007/978-1-4684-5877-0_32] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M E Fitzsimmons
- Department of Pharmacology, University of Rochester, NY 14642
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29
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Abstract
In 1916 a relationship was postulated between the occurrence of aplastic anaemia in cattle and the soy bean meal that they had been fed, which had been extracted with trichloroethylene. The toxic compound was later identified as S-(1,2-dichlorovinyl)-L-cysteine (DCV-Cys). In addition to effects on the hemopoietic system it also produced nephrotoxicity in calves. In rats only renal tubular necrosis was found. Further research demonstrated that other halogenated hydrocarbons produced similar nephrotoxicity. The haloalkenyl cysteine-S-conjugates (Cys-S-conjugates) have extensively been studied; this has provided new insight into the biochemical processes that lead to nephrotoxicity. It has been shown that a combination of transport processes and specific metabolic pathways, resulting in reactive intermediates that bind to cellular macromolecules, makes the kidney vulnerable to the noxious effects of the haloalkenyl Cys-S-conjugates. The first part of this review gives a brief overview of the bioactivation of the haloalkenes; in the second part the present knowledge of the underlying mechanisms of cytotoxicity will be outlined.
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Affiliation(s)
- J F Nagelkerke
- Division of Toxicology, Center for Bio-Pharmaceutical Sciences, Sylvius Laboratory, University of Leiden, The Netherlands
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30
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Lock EA, Schnellmann RG. The effect of haloalkene cysteine conjugates on rat renal glutathione reductase and lipoyl dehydrogenase activities. Toxicol Appl Pharmacol 1990; 104:180-90. [PMID: 2360207 DOI: 10.1016/0041-008x(90)90293-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
An early event in the nephrotoxicity of haloalkene cysteine conjugates is their metabolism by cysteine conjugate beta-lyase to generate a reactive "thiol moiety" which binds to protein. This reactive metabolite(s) has been reported to cause mitochondrial dysfunction. We have examined the effect of three haloalkene cysteine conjugates on the activity of rat renal cortical cytosolic glutathione reductase and mitochondrial lipoyl dehydrogenase, two enzymes which have been reported to be inhibited by S-(1,2-dichlorovinyl)-L-cysteine (DCVC) in the liver. N-Acetyl-S-(1,2,3,4,4-pentachloro-1,3-butadienyl)-L- cysteine (N-acetyl PCBC) produced a time- and concentration-dependent inhibition of glutathione reductase and kinetic studies showed that the inhibition was noncompetitive with a Ki of 215 microM. The enzyme activity from male rat kidney was more sensitive to N-acetyl PCBC than that from female rat kidney. Aminooxyacetic acid, an inhibitor of cysteine conjugate beta-lyase, and bis-p-nitrophenyl phosphate, an amidase inhibitor, blocked the effect of N-acetyl PCBC on glutathione reductase, indicating that metabolism by the cytosol is required to produce enzyme inhibition. S-(1,1,2,2-Tetrafluoroethyl)-L-cysteine (TFEC) and DCVC are also noncompetitive inhibitors of glutathione reductase but are less active than N-acetyl PCBC with Ki's of 2.6 and 6.2 mM for DCVC and TFEC, respectively, DCVC produced a time- and concentration-dependent inhibition of lipoyl dehydrogenase and kinetic studies showed that the inhibition was noncompetitive with a Ki of 762 microM. TFEC and PCBC also inhibit lipoyl dehydrogenase. Aminooxyacetic acid blocked the effect of DCVC, TFEC, and PCBC on lipoyl dehydrogenase, indicating that metabolism by the mitochondrial fraction is required to produce enzyme inhibition. Glutathione reductase activity in the renal cortex of male rats treated with 200 mg/kg hexachloro-1,3-butadiene (HCBD) was inhibited as early as 1 hour after dosing, before signs of marked morphological damage. The activity of lipoyl dehydrogenase was also reduced but was only statistically significant 8 hr after dosing when there was marked renal dysfunction. These findings indicate that the reactive thiol moiety formed by cysteine conjugate beta-lyase cleavage of PCBC can inhibit both glutathione reductase and lipoyl dehydrogenase activities in vivo following HCBD administration. We suggest that such inhibition is a general phenomenon, occurring with diverse and as yet unidentified renal proteins. The critical nature of mitochondrial function and the generation of reactive metabolites within this compartment make this organelle a prime target.
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Affiliation(s)
- E A Lock
- Biochemical Toxicology Section, ICI Central Toxicology Laboratory, Cheshire, United Kingdom
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31
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Abstract
Glutathione (GSH) conjugation reactions in the metabolism of hexachlorobutadiene (HCBD), in rats and mice, initiate a series of metabolic events resulting in the formation of reactive intermediates in the proximal tubular cells of the kidney. The GSH S-conjugate 1-(glutathion-S-yl)-1,2,3,4,4-pentachlorobutadiene (GPCB), which is formed by conjugation of HCBD with GSH in the liver, is not reactive and is eliminated from the liver in the bile or plasma, or both. GPCB may be translocated intact to the kidney and processed there by gamma-glutamyl transpeptidase and dipeptidases to the corresponding cysteine S-conjugate. Alternatively, gamma-glutamyl transpeptidase and dipeptidases present in epithelial cells of the bile duct and small intestine may catalyse the conversion of GPCB to cysteine S-conjugates. The kidney concentrates both GSH and cysteine S-conjugates and processes GSH conjugates to cysteine S-conjugates. A substantial fraction of HCBD cysteine S-conjugate thus concentrated in the kidney is metabolized by renal cysteine conjugate beta-lyase to reactive intermediates. The selective formation of reactive intermediates in the kidney most likely accounts for the organ-specific effects of HCBD. Alternatively, cysteine S-conjugates may be acetylated to yield excretable mercapturic acids.
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Affiliation(s)
- W Dekant
- Institut für Toxikologie, Universität Würzburg, FRG
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32
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Schnellmann RG, Cross TJ, Lock EA. Pentachlorobutadienyl-L-cysteine uncouples oxidative phosphorylation by dissipating the proton gradient. Toxicol Appl Pharmacol 1989; 100:498-505. [PMID: 2551076 DOI: 10.1016/0041-008x(89)90297-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A very early event in the toxicity of pentachlorobutadienyl-L-cysteine (PCBC) to rabbit renal proximal tubules is uncoupling of oxidative phosphorylation (R.G. Schnellmann, E. A. Lock, and L. J. Mandel (1986), Toxicologist 6, 176; (1987), Toxicol. Appl. Pharmacol. 90, 521). The mechanism of PCBC uncoupling of mitochondrial oxidative phosphorylation has been investigated using isolated rabbit renal cortical mitochondria (RCM). PCBC increased state 4 respiration of RCM respiring on pyruvate/malate or succinate in a concentration (10-100 microM)- and time (1-5 min)-dependent manner. PCBC also increased state 4 respiration in the presence of oligomycin, an inhibitor of F0F1-ATPase. The effect of PCBC on mitochondrial proton permeability was determined by measuring passive mitochondrial swelling. After a 2-min exposure to PCBC, RCM swelled when placed in NH4Cl or NaCl, but not KCl or sucrose. The protonophore carbonyl cyanide p-trifluoromethoxyphenyl hydrazone (FCCP) (1 microM) produced similar effects. After 5 min, RCM swelled when placed in NH4Cl, NaCl, or KCl, but not in sucrose. Aminooxyacetic acid, an inhibitor of cysteine conjugate beta-lyase, blocked the effects of PCBC on respiration, indicating that PCBC can be metabolized by RCM to produce RCM toxicity. These results show that PCBC initially uncouples oxidative phosphorylation by dissipating the proton gradient. Subsequently, additional ion permeabilities occur. These results are in complete agreement with previous observations in rabbit renal proximal tubule suspensions.
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Affiliation(s)
- R G Schnellmann
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602
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Darnerud PO, Brandt I, Feil VJ, Bakke JE. S-(1,2-dichloro-[14C]vinyl)-L-cysteine (DCVC) in the mouse kidney: correlation between tissue-binding and toxicity. Toxicol Appl Pharmacol 1988; 95:423-34. [PMID: 2903585 DOI: 10.1016/0041-008x(88)90360-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Uniformly 14C-labeled DCVC and unlabeled DCVC were synthesized and used for autoradiographical and histopathological studies. Four hours after administration of [14C]DCVC (25 mg/kg body wt), a strong binding of radioactivity was observed in the straight proximal tubular cells. Later, the radioactivity was redistributed from the proximal tubules to scattered foci in the kidney medulla, suggesting desquamation and tubular transport of labeled epithelial cells. The redistribution was less pronounced at a lower [14C]DCVC dose (5 mg/kg body wt). Localization of [14C]DCVC was also observed in the liver, exocrine pancreas, and stomach (fundal part), although at a lower level than in the kidney. While the low dose (5 mg/kg body wt) produced a moderate lesion in the straight proximal tubules 24 hr after DCVC, the high dose (25 mg/kg body wt) not only induced a more pronounced lesion in this tubular segment but also extended the lesion to other tubular segments, including the subcapsular region. The results indicate binding of (a) vinyl-containing metabolite(s) to the straight portion of the proximal tubules, where a primary lesion is subsequently developed. Depending on dose, a "secondary" lesion appears in the subcapsular region, topographically different from the DCVC-binding region.
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Affiliation(s)
- P O Darnerud
- Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences, Uppsala
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34
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Stevens JL, Ayoubi N, Robbins JD. The role of mitochondrial matrix enzymes in the metabolism and toxicity of cysteine conjugates. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69084-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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35
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Anders MW, Lash L, Dekant W, Elfarra AA, Dohn DR. Biosynthesis and biotransformation of glutathione S-conjugates to toxic metabolites. Crit Rev Toxicol 1988; 18:311-41. [PMID: 3288445 DOI: 10.3109/10408448809037470] [Citation(s) in RCA: 165] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The material presented in this review deals with the hypothesis that the nephrotoxicity of certain halogenated alkanes and alkenes is associated with hepatic biosynthesis of glutathione S-conjugates, which are further metabolized to the corresponding cysteine S-conjugates. Some glutathione or cysteine S-conjugates may be direct-acting nephrotoxins, but most cysteine S-conjugates require bioactivation by renal, pyridoxal phosphate-dependent enzymes, such as cysteine conjugate beta-lyase (beta-lyase). The biosynthesis of glutathione S-conjugates is catalyzed by both the cytosolic and the microsomal glutathione S-transferases, although the latter enzyme is a better catalyst for the reaction of haloalkenes with glutathione. When glutathione S-conjugate formation yields sulfur mustards, as occurs with vicinal-dihaloethanes, the S-conjugates are direct-acting toxins. In contrast, the S-conjugates formed from fluoro- and chloroalkenes yield S-alkyl- or S-vinyl glutathione conjugates, respectively, which are metabolized to the corresponding cysteine S-conjugates by gamma-glutamyltransferase and dipeptidases; inhibition of these enzymes blocks the toxicity of the glutathione S-conjugates. The cysteine S-conjugates must be metabolized by beta-lyase for the expression of toxicity; the beta-lyase inhibitor aminooxyacetic acid blocks the toxicity of cysteine S-conjugates, and the corresponding alpha-methyl cysteine S-conjugates, which cannot be metabolized by beta-lyase, are not toxic. Moreover, probenecid, an inhibitor of renal anion transport system, blocks the toxicity of cysteine S-conjugates, which cannot be metabolized by beta-lyase, are not toxic. Moreover, probenecid, an inhibitor of renal anion transport system, blocks the toxicity of cysteine S-conjugates. Homocysteine S-conjugates are also potent cyto- and nephrotoxins. The high renal content of gamma-glutamyltransferase and the renal anion transport system are probably determinants of kidney tissue as a target site. Biochemical studies indicate that renal mitochondrial dysfunction is produced by the cysteine S-conjugates. Finally, some of the glutathione and cysteine conjugates are mutagenic in the Ames test, and reactive intermediates formed by the action of beta-lyase may contribute to the nephrocarcinogenicity of certain chloroalkenes.
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Affiliation(s)
- M W Anders
- Department of Pharmacology, School of Medicine and Dentistry, University of Rochester, New York
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Lock EA. Studies on the mechanism of nephrotoxicity and nephrocarcinogenicity of halogenated alkenes. Crit Rev Toxicol 1988; 19:23-42. [PMID: 3056657 DOI: 10.3109/10408448809040816] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
There is now a considerable weight of evidence from studies in a number of different laboratories with different haloalkenes to suggest that these compounds undergo conjugation with glutathione followed by degradation of the S-conjugate (Figure 1) to produce cytotoxic, and in some cases mutagenic, metabolites. These effects are dependent upon the sequential metabolism by gamma-glutamyl transferase and dipeptidases to produce the cysteine conjugates, and the presence of renal transport systems which concentrate the chemical in renal cells. These conjugates then appear to undergo further metabolism to a reactive thiol by the renal enzyme cysteine-conjugate beta-lyase, a process which can be blocked by inhibiting the enzyme with AOAA. Renal beta-lyase is present in both the cytosol and mitochondrial fractions, but toxicity studies in isolated cells and mitochondria indicate that the primary mode of action of these compounds is the inhibition of mitochondrial respiration, suggesting that the mitochondrial beta-lyase may be more important than the cytosolic enzyme in cysteine S-conjugate bioactivation. In addition to the renal cell injury caused by the presumed reactive thiol metabolite, reaction with DNA also occurs as the chlorinated, but not fluorinated, analogs are mutagenic, and in the case of HCBD, carcinogenic. Thus the target organ, cellular and subcellular specificity of haloalkene-S-conjugates, is due to the presence of bioactivating enzymes and the susceptibility of certain biochemical processes. The precise relationship between (1) the mitochondrial effects and cytotoxicity and (2) the interaction of the chemical with DNA and its mutagenicity require more precise understanding in order to elucidate the mechanism of S-conjugate-induced cell death and carcinogenicity. The routes and rates of metabolism of some of these compounds, with respect to glutathione conjugation vs. oxidative metabolism, in both experimental animals and man are required to help assess the risk associated with this class of chemicals.
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Affiliation(s)
- E A Lock
- Department of Biochemical Toxicology, Imperial Chemical Industries PLC, Macclesfield, Cheshire, United Kingdom
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Wallin A, Jones TW, Vercesi AE, Cotgreave I, Ormstad K, Orrenius S. Toxicity of S-pentachlorobutadienyl-L-cysteine studied with isolated rat renal cortical mitochondria. Arch Biochem Biophys 1987; 258:365-72. [PMID: 3674880 DOI: 10.1016/0003-9861(87)90357-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
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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Affiliation(s)
- A Wallin
- Department of Forensic Medicine, Karolinska Institute, Stockholm, Sweden
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Schnellmann RG, Lock EA, Mandel LJ. A mechanism of S-(1,2,3,4,4-pentachloro-1,3-butadienyl)-L-cysteine toxicity to rabbit renal proximal tubules. Toxicol Appl Pharmacol 1987; 90:513-21. [PMID: 3660416 DOI: 10.1016/0041-008x(87)90143-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
S-(1,2,3,4,4-Pentachloro-1,3-butadienyl)-L-cysteine (PCBC) has been identified as the penultimate compound responsible for hexachlorobutadiene-induced nephrotoxicity. The primary goal of these studies was to determine the mechanism of PCBC-induced toxicity in rabbit renal proximal tubules by examining the early changes in tubular physiology. PCBC (20-500 microM) induced a specific sequence of toxic events. Following 15 min of exposure, 200 microM PCBC increased basal (25%) and ouabain-insensitive (78%) respiration. This was followed by a decrease in basal (46%), nystatin-stimulated (54%), and ouabain-insensitive (21%) respiration and a decrease in glutathione content (79%). Finally, there was a decrease in cell viability as measured by a decrease in LDH retention at 60 min. Direct probing of mitochondrial function revealed that the initial increase in respiration resulted from the uncoupling of oxidative phosphorylation, while the late changes in respiration appeared to result from gross mitochondrial damage characterized by inhibited state 3 respiration, inhibited cytochrome c-cytochrome oxidase, and inhibited electron transport. Studies utilizing tubules with decreased glutathione content revealed that glutathione plays little if any role in the early events of PCBC-induced toxicity. These results suggest that PCBC-induced mitochondrial dysfunction may initiate the renal proximal tubule injury.
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Affiliation(s)
- R G Schnellmann
- Department of Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602
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Jones TW, Wallin A, Thor H, Gerdes RG, Ormstad K, Orrenius S. The mechanism of pentachlorobutadienyl-glutathione nephrotoxicity studied with isolated rat renal epithelial cells. Arch Biochem Biophys 1986; 251:504-13. [PMID: 3800381 DOI: 10.1016/0003-9861(86)90358-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Isolated renal epithelial cells were used to study the mechanism of toxicity of pentachlorobutadienyl-glutathione (PCBG), a nephrotoxic glutathione conjugate of hexachlorobutadiene. The cytotoxicity of PCBG displayed a very steep dose-response relationship; at 10 microM PCBG no toxicity was observed whereas 25, 50, and 100 microM PCBG all resulted in a similar degree of toxicity. In all cases, loss of cell viability was observed only after a 30-min lag period and reached a plateau of 50 to 60% nonviable cells between 90 and 100 min. Toxic doses of PCBG also resulted in the depletion of cellular thiols. Blocking PCBG metabolism by inhibition of gamma-glutamyl transpeptidase [1-gamma-L-glutamyl-2-(2-carboxyphenyl)hydrazine (anthglutin), 2 mM] or renal cysteine conjugate beta-lyase (aminooxyacetic acid, 0.5 mM) resulted in complete protection against PCBG-induced cell damage. Exposure of isolated renal epithelial cells to 100 microM PCBG resulted in the rapid formation of plasma membrane blebs which appeared to be associated with a loss of Ca2+ from the mitochondrial compartment and an elevation of cytosolic Ca2+ concentration as measured by Quin-2. PCBG treatment also resulted in the inhibition of cell respiration and a marked depletion of cellular ATP content, indicating additional mitochondrial effects of the toxin. Our results support a role for renal cysteine conjugate beta-lyase in the metabolic activation of PCBG and suggest that PCBG-induced renal cell injury may be the result of selective effects on mitochondrial function.
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Lash LH, Anders MW. Cytotoxicity of S-(1,2-dichlorovinyl)glutathione and S-(1,2-dichlorovinyl)-L-cysteine in isolated rat kidney cells. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)69273-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Banki K, Elfarra AA, Lash LH, Anders MW. Metabolism of S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine to hydrogen sulfide and the role of hydrogen sulfide in S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine-induced mitochondrial toxicity. Biochem Biophys Res Commun 1986; 138:707-13. [PMID: 3741429 DOI: 10.1016/s0006-291x(86)80554-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The nephrotoxic cysteine S-conjugate S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine (CTFC) is metabolized by kidney homogenates and subcellular fractions to pyruvate and a reactive thiol, which is cytotoxic and partially decomposes to yield hydrogen sulfide and thiosulfate. Although hydrogen sulfide is a potent mitochondrial poison, the mitochondrial toxicity of CTFC is not attributable to hydrogen sulfide formation, as shown by different sites of inhibition of mitochondrial respiration by CTFC and hydrogen sulfide. The efficient mitochondrial oxidation of hydrogen sulfide apparently serves to protect mitochondria against the toxic effects of hydrogen sulfide generated from CTFC.
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Abstract
A variety of model systems has been used to study mechanisms of cytotoxicity in vitro. These include purified enzymes, subcellular fractions, freshly isolated cells and perfused organs. Freshly isolated cells provide a number of distinct advantages and have become a popular experimental model in many laboratories. This paper discusses some of the advantages and disadvantages of isolated cell preparations for studies of cytotoxicity and summarizes the results of recent work in which isolated hepatocytes and renal epithelial cells have been used to examine the metabolism and toxicity of menadione and hexachloro-1,3-butadiene.
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Lash LH, Elfarra AA, Anders MW. Renal cysteine conjugate beta-lyase. Bioactivation of nephrotoxic cysteine S-conjugates in mitochondrial outer membrane. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)38472-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Elfarra AA, Jakobson I, Anders MW. Mechanism of S-(1,2-dichlorovinyl)glutathione-induced nephrotoxicity. Biochem Pharmacol 1986; 35:283-8. [PMID: 2867768 DOI: 10.1016/0006-2952(86)90527-7] [Citation(s) in RCA: 176] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
S-(1,2-Dichlorovinyl)glutathione and S-(1,2-dichlorovinyl)-DL-cysteine are potent nephrotoxins. Agents that inhibit gamma-glutamyl transpeptidase, cysteine conjugate beta-lyase, and renal organic anion transport systems, namely L-(alpha S,5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (AT-125), aminooxyacetic acid, and probenecid, respectively, protected against S-conjugate-induced nephrotoxicity. Furthermore, S-(1,2-dichlorovinyl)-DL-alpha-methylcysteine, which cannot be cleaved by cysteine conjugate beta-lyase, was not nephrotoxic. These results strongly support a role for renal gamma-glutamyl transpeptidase, cysteine conjugate beta-lyase, and organic anion transport systems in S-(1,2-dichlorovinyl)glutathione- and S-(1,2-dichlorovinyl)cysteine-induced nephrotoxicity.
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Anders MW, Lash LH, Elfarra AA. Nephrotoxic amino acid and glutathione S-conjugates: formation and renal activation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1986; 197:443-55. [PMID: 3766274 DOI: 10.1007/978-1-4684-5134-4_43] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Hassall CD, Brendel K, Gandolfi AJ. Regulation of a S(trans-1,2-dichlorovinyl)-L-cysteine-induced renal tubular toxicity by glutathione. J Appl Toxicol 1983; 3:321-5. [PMID: 6677655 DOI: 10.1002/jat.2550030610] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The nephrotoxin S-(1,2-dichlorovinyl)-L-cysteine (DCVC) is cleaved in the renal tubules to produce a reactive electrophilic intermediate. If this intermediate is responsible for the toxicity, addition of the nucleophilic scavenger glutathione (GSH) should decrease toxicity, and depletion of tubular GSH should enhance toxicity. GSH was added to isolated rabbit renal tubules simultaneously with, 15 min before, and 15 min after the addition of DCVC. The active accumulation of the organic anion para-aminohippuric acid (PAH) and organic cation tetraethylammonium bromide (TEA) was used as an index of renal toxicity. Incubation of renal tubules with 0.01-1 mM DCVC for 15 min decreased active transport, with complete inhibition at 1 mM. This was accompanied by a 50% decrease in non-protein sulfhydryl concentration. The addition of GSH (6 mM) simultaneously with DCVC completely prevented any decrease in active transport. The addition of GSH (6 mM) to tubules in which active transport was inhibited by DCVC reversed the inhibition to 80% of control. Similar enhancement of active transport occurred when tubules isolated 1 h after in vivo exposure to DCVC at 20-100 mg kg-1 were incubated with GSH (6 mM). Preincubation of renal tubules with GSH (5-15 mM) made them more refractory to the DCVC-induced decreased PAH and TEA transport. The inhibition of active transport by DCVC is enhanced if the tubular non-protein sulfhydryl is first lowered by diethyl maleate or glycidol. Thus, the tubular GSH concentration appears to be an integral component in regulating the alterations in active transport caused by DCVC.
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Alston TA, Bright HJ. Conversion of trifluoromethionine to a cross-linking agent by gamma-cystathionase. Biochem Pharmacol 1983; 32:947-50. [PMID: 6838645 DOI: 10.1016/0006-2952(83)90608-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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48
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Hassall CD, Gandolfi AJ, Brendel K. Effect of halogenated vinyl cysteine conjugates on renal tubular active transport. Toxicology 1983; 26:285-94. [PMID: 6857701 DOI: 10.1016/0300-483x(83)90089-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Addition of halogenated vinyl cysteine conjugates to isolated rabbit kidney tubule suspensions resulted in a decrease in the active transport of para-aminohippuric acid (PAH) and tetraethylammonium bromide (TEA). At 10(-5) M vinyl cysteine conjugate, tubule to medium accumulation ratios (T/M) were similar to those of controls while at 10(-3) M the T/M values decreased to 1, indicating complete inhibition of active accumulation of PAH or TEA. The decreased active transport was not caused by inhibition of mitochondrial oxidation since incubations in the presence of 10(-3) M halogenated vinyl cysteine did not inhibit tubule O2 utilization or production of 14CO2 from [14C]glucose or [14C]succinate. A mechanism is proposed whereby toxicity may result from covalent binding of an active intermediate, produced by enzyme cleavage, to membrane associated nucleophilic groups thereby decreasing active transport.
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Yesair DW, Taylor RF. Pharmacological implications of the interaction of heavy metals with novel macromolecular lipids. Drug Metab Rev 1982; 13:517-33. [PMID: 7105973 DOI: 10.3109/03602538209029993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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50
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Cunningham ML, Gandolfi AJ, Brendel K, Sipes IG. Covalent binding of halogenated volatile solvents to subcellular macromolecules in hepatocytes. Life Sci 1981; 29:1207-12. [PMID: 6170853 DOI: 10.1016/0024-3205(81)90224-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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