Bioactivation of [13C]Dichloromethane in Mouse, Rat, and Human Liver Cytosol: 13C Nuclear Magnetic Resonance Spectroscopic Studies

Hashmi, M.; Dechert, S.; Dekant, W.; Anders, M. W.

doi:10.1021/tx00039a004

Cited by 30 publications

(14 citation statements)

References 33 publications

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“…(i) diol-epoxides from CYP1A1-dependent oxidation of benzo[a]pyrene (B[a]P) found in tobacco smoke and exhaust fumes (Uppstad et al, 2010), (ii) diazo groups resulting from the a-hydroxylation of tobacco nitrosamines by the CYP2A enzyme family (Brown et al, 2007), (iii) formaldehyde hydrate as a by-product from the glutathione conjugation through inhalation of dichloromethane vapors (Hashmi et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

Targeted omics analyses, and metabolic enzyme activity assays demonstrate maintenance of key mucociliary characteristics in long term cultures of reconstituted human airway epithelia

Baxter

Thain²,

Banerjee

et al. 2015

Toxicology in Vitro

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3D reconstituted respiratory epithelia have emerged as better in vitro models for toxicological testing compared to cell lines due to the conservation of key morphological features and functions. MucilAir™ is a commercially available human airway epithelia system that can potentially maintain functional attributes for up to a year, however, detailed mucociliary characteristics and xenobiotic metabolism relevant to inhaled pro-toxicant bioactivation is lacking. Here, we assessed in MucilAir™ some key biomarkers that are characteristic of the respiratory epithelia including morphology, function and xenobiotics metabolism. The end points that were measured included targeted proteomics using a panel of 243 airway surface liquid (ASL) proteins, cilia beat frequency (CBF), a qRT-PCR screen of xenobiotic metabolizing enzymes, and CYP2A6/13, CYP1A1/1B1 activity. Comparison of ASL proteomics with human sputum identified key proteins common to both matrices, but present at different levels. Xenobiotic metabolism gene profiling demonstrated strong similarities with the normal human lung and did not reveal any consistent changes when assessed over a 6 month period. Inducibility and activity of CYP1A1/1B1 and activity of CYP2A6/2A13 were present at one month in culture and maintained in one tested MucilAir™ donor for several months. In conclusion, MucilAir™ presented important morphological and metabolic characteristics of a mucociliary epithelium in short and long term culture. MucilAir™ is therefore a potentially useful model to test repeated sub-cytotoxic doses of toxicants.

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Section: Introductionmentioning

confidence: 99%

Targeted omics analyses, and metabolic enzyme activity assays demonstrate maintenance of key mucociliary characteristics in long term cultures of reconstituted human airway epithelia

Baxter

Thain²,

Banerjee

et al. 2015

Toxicology in Vitro

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“…al., 2001. The work of Dekant and Anders (Hashmi et al, 1994) also suggests a short half-life for GSCH 2 Cl.…”

Section: Dihalomethanesmentioning

confidence: 96%

Activation of Dihaloalkanes by Thiol-dependent Mechanisms

Guengerich¹

2003

BMB Reports

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Dihaloalkanes constitute an important group of chemicals because of their widespread use in industry and agriculture and their potential for causing toxicity and cancer. Chronic toxic effects are considered to depend upon bioactivation, either by oxidation or thiol conjugation. Considerable evidence links genotoxicity and cancer with glutathione conjugations reactions, and some aspects of the mechanisms have been clarified with 1,2-dihaloalkanes and dihalomethanes. Recently the DNA repair protein O6-alkylguanine transferase has been shown to produce cytotoxicity and genotoxicity by means of a thiol-dependent process with similarities to the glutathione reactions.

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“…These results are consistent with a reaction mechanism that involves displacement of chloride by glutathione to afford S-(αchlorocarboxymethyl)glutathione as an intermediate ; solvolysis would give the hemithioacetal S-(α-hydroxycarboxymethyl)glutathione, which may eliminate glutathione to give glyoxylic acid. Similarly, S-chloromethylglutathione has been identified as an intermediate in the GST Theta-catalysed oxygenation of dichloromethane [23].…”

Section: Table 2 Catalytic Activities Of the Purified Rat-liver Enzymmentioning

confidence: 99%

Glutathione transferase Zeta catalyses the oxygenation of the carcinogen dichloroacetic acid to glyoxylic acid

Zheng

Board

Anders

1998

Biochemical Journal

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129

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Dichloroacetic acid (DCA), a common drinking-water contaminant, is hepatocarcinogenic in rats and mice, and is a therapeutic agent used clinically in the management of lactic acidosis. DCA is biotransformed to glyoxylic acid by glutathione-dependent cytosolic enzymes in vitro and is metabolized to glyoxylic acid in vivo. The enzymes that catalyse the oxygenation of DCA to glyoxylic acid have not, however, been identified or characterized. In the present investigation, an enzyme that catalyses the glutathione-dependent oxygenation of DCA was purified to homogeneity (587-fold) from rat liver cytosol. SDS/PAGE and HPLC gel-filtration chromatography showed that the purified enzyme had a molecular mass of 27-28 kDa. Sequence analysis showed that the N-terminus of the purified protein was blocked. An internal sequence of 30 amino acid residues was obtained that matched the recently discovered human glutathione transferase Zeta well [Board, Baker, Chelvanayagam and Jermiin (1997) Biochem. J. 328, 929-935]. Western-blot analysis showed that the purified rat-liver enzyme cross-reacted with rabbit antiserum raised against recombinant human glutathione transferase Zeta. The apparent Km and Vmax values of the purified enzyme with DCA as the variable substrate were 71.4 microM and 1334 nmol/min per mg of protein, respectively; the Km for glutathione was 59 microM. Both the purified rat-liver enzyme and the recombinant human enzyme showed high activity with DCA as the substrate. These results demonstrate that the glutathione-dependent oxygenation of DCA to glyoxylic acid is catalysed by a Zeta-class glutathione transferase.

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Bioactivation of [13C]Dichloromethane in Mouse, Rat, and Human Liver Cytosol: 13C Nuclear Magnetic Resonance Spectroscopic Studies

Cited by 30 publications

References 33 publications

Targeted omics analyses, and metabolic enzyme activity assays demonstrate maintenance of key mucociliary characteristics in long term cultures of reconstituted human airway epithelia

Targeted omics analyses, and metabolic enzyme activity assays demonstrate maintenance of key mucociliary characteristics in long term cultures of reconstituted human airway epithelia

Activation of Dihaloalkanes by Thiol-dependent Mechanisms

Glutathione transferase Zeta catalyses the oxygenation of the carcinogen dichloroacetic acid to glyoxylic acid

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