Ethylene Glycol Monomethyl Ether–Induced Toxicity Is Mediated through the Inhibition of Flavoprotein Dehydrogenase Enzyme Family

Ethylene glycol monomethyl ether (EGME) is a widely used industrial solvent known to cause adverse effects to human and other mammals. Organs with high metabolism and rapid cell division, such as testes, are especially sensitive to its actions. In order to gain mechanistic understanding of EGME-induced toxicity, an untargeted metabolomic analysis was performed in rats. Male rats were administrated with EGME at 30 and 100 mg/kg/day. At days 1, 4, and 14, serum, urine, liver, and testes were collected for analysis. Testicular injury was observed at day 14 of the 100 mg/kg/day group only. Nearly 1900 metabolites across the four matrices were profiled using liquid chromatography-mass spectrometry/mass spectrometry and gas chromatography-mass spectrometry. Statistical analysis indicated that the most significant metabolic perturbations initiated from the early time points by EGME were the inhibition of choline oxidation, branched-chain amino acid catabolism, and fatty acid β-oxidation pathways, leading to the accumulation of sarcosine, dimethylglycine, and various carnitine- and glycine-conjugated metabolites. Pathway mapping of these altered metabolites revealed that all the disrupted steps were catalyzed by enzymes in the primary flavoprotein dehydrogenase family, suggesting that inhibition of flavoprotein dehydrogenase–catalyzed reactions may represent the mode of action for EGME-induced toxicity. Similar urinary and serum metabolite signatures are known to be the hallmarks of multiple acyl-coenzyme A dehydrogenase deficiency in humans, a genetic disorder because of defects in primary flavoprotein dehydrogenase reactions. We postulate that disruption of key biochemical pathways utilizing flavoprotein dehydrogenases in conjugation with downstream metabolic perturbations collectively result in the EGME-induced tissue damage.

[1]  F. Frerman,et al.  Glutaric acidemia type II: gene structure and mutations of the electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO) gene. , 2002, Molecular genetics and metabolism.

[2]  S. Ghisla,et al.  Acyl-CoA dehydrogenases. A mechanistic overview. , 2004, European journal of biochemistry.

[3]  J. Bełtowski,et al.  Asymmetric dimethylarginine (ADMA) as a target for pharmacotherapy. , 2006, Pharmacological reports : PR.

[4]  B. Amendt,et al.  Short-chain acyl-coenzyme A dehydrogenase deficiency. Clinical and biochemical studies in two patients. , 1987, The Journal of clinical investigation.

[5]  B. Andresen,et al.  2-ethylhydracrylic aciduria in short/branched-chain acyl-CoA dehydrogenase deficiency: application to diagnosis and implications for the R-pathway of isoleucine oxidation. , 2005, Clinical chemistry.

[6]  R. Boatman.  International industry initiatives to improve the glycol ether health effects knowledge base. , 2005, Toxicology letters.

[7]  C. Heizmann,et al.  Evaluation of urinary acylglycines by electrospray tandem mass spectrometry in mitochondrial energy metabolism defects and organic acidurias. , 2000, Molecular genetics and metabolism.

[8]  R. Chalmers,et al.  Proton NMR spectroscopic analysis of multiple acyl-CoA dehydrogenase deficiency--capacity of the choline oxidation pathway for methylation in vivo. , 1998, Biochimica et biophysica acta.

[9]  D. Turnbull,et al.  ETFDH mutations as a major cause of riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency. , 2007, Brain : a journal of neurology.

[10]  M. Danielsen,et al.  Methoxyacetic Acid Disregulation of Androgen Receptor and Androgen-Binding Protein Expression in Adult Rat Testis1 , 2003, Biology of reproduction.

[11]  J. Doe,et al.  Comparative aspects of the reproductive toxicology by inhalation in rats of ethylene glycol monomethyl ether and propylene glycol monomethyl ether. , 1983, Toxicology and applied pharmacology.

[12]  K. Isselbacher,et al.  Isovaleric acidemia: a new genetic defect of leucine metabolism. , 1966, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Jerry Vockley,et al.  Isovaleric acidemia: New aspects of genetic and phenotypic heterogeneity , 2006, American journal of medical genetics. Part C, Seminars in medical genetics.

[14]  F. Frerman,et al.  Glutaric Acidemia Type II: Heterogeneity of Clinical and Biochemical Phenotypes , 1990, Pediatric Research.

[15]  M R Cullen,et al.  Effects of exposure to ethylene glycol ethers on shipyard painters: II. Male reproduction. , 1988, American journal of industrial medicine.

[16]  R. Foote,et al.  Disruption of spermatogenesis in rabbits consuming ethylene glycol monomethyl ether. , 1997, Reproductive toxicology.

[17]  A. Inomata,et al.  Collaborative work on evaluation of ovarian toxicity. 11) Two- or four-week repeated-dose studies and fertility study of ethylene glycol monomethyl ether in female rats. , 2009, The Journal of toxicological sciences.

[18]  S. Zeisel.  Choline: critical role during fetal development and dietary requirements in adults. , 2006, Annual review of nutrition.

[19]  D. Hale,et al.  Clinical and biochemical characterization of short-chain acyl-coenzyme A dehydrogenase deficiency. , 1995, The Journal of pediatrics.

[20]  I. Horii,et al.  Effects of male reproductive toxicants on gene expression in rat testes. , 2005, The Journal of toxicological sciences.

[21]  D. Waxman,et al.  Toxicity of ethylene glycol monomethyl ether: impact on testicular gene expression. , 2008, International journal of andrology.

[22]  N. Hecht,et al.  Rat pachytene spermatocytes down-regulate a polo-like kinase and up-regulate a thiol-specific antioxidant protein, whereas sertoli cells down-regulate a phosphodiesterase and up-regulate an oxidative stress protein after exposure to methoxyethanol and methoxyacetic acid. , 1998, Endocrinology.

[23]  N. Gregersen,et al.  Hypoglycaemia and elevated urine ethylmalonic acid in a child homozygous for the short‐chain acyl‐CoA dehydrogenase 625G > A gene variation , 2002, Acta paediatrica.

[24]  John T. Wei,et al.  Metabolomic profiles delineate potential role for sarcosine in prostate cancer progression , 2009, Nature.

[25]  M. Wyss,et al.  Creatine and creatinine metabolism. , 2000, Physiological reviews.

[26]  L. D. Schroeder,et al.  Isolated 2-methylbutyrylglycinuria caused by short/branched-chain acyl-CoA dehydrogenase deficiency: identification of a new enzyme defect, resolution of its molecular basis, and evidence for distinct acyl-CoA dehydrogenases in isoleucine and valine metabolism. , 2000, American journal of human genetics.

[27]  G. Lenaz.  A critical appraisal of the mitochondrial coenzyme Q pool , 2001, FEBS letters.

[28]  S. Z. Abdel‐Rahman,et al.  Exposure to Ethylene Glycol Monomethyl Ether: Clinical and Cytogenetic Findings , 2002, Archives of environmental health.

[29]  R. Chapin,et al.  Effects of ethylene glycol monomethyl ether on various parameters of testicular function in the F344 rat. , 1984, Environmental health perspectives.

[30]  Corey D. DeHaven,et al.  Integrated, nontargeted ultrahigh performance liquid chromatography/electrospray ionization tandem mass spectrometry platform for the identification and relative quantification of the small-molecule complement of biological systems. , 2009, Analytical chemistry.

[31]  S. Korman.  Inborn errors of isoleucine degradation: a review. , 2006, Molecular genetics and metabolism.

[32]  J. Vockley,et al.  Rare Disorders of Metabolism with Elevated Butyryl- and Isobutyryl-Carnitine Detected by Tandem Mass Spectrometry Newborn Screening , 2003, Pediatric Research.

[33]  L. Welch,et al.  Effect of exposure to ethylene glycol ethers on shipyard painters: III. Hematologic effects. , 1988, American journal of industrial medicine.

[34]  T. Hanley,et al.  Ethylene glycol monomethyl ether (EGME) and propylene glycol monomethyl ether (PGME): inhalation fertility and teratogenicity studies in rats, mice and rabbits. , 1984, Environmental health perspectives.

[35]  J. Vockley,et al.  Acyl-CoA Dehydrogenases: Dynamic History of Protein Family Evolution , 2009, Journal of Molecular Evolution.

[36]  H. Waterham,et al.  Clinical, biochemical, and genetic heterogeneity in short-chain acyl-coenzyme A dehydrogenase deficiency. , 2006, JAMA.

[37]  Jung‐Ja P. Kim,et al.  Acyl-CoA dehydrogenases and acyl-CoA oxidases. Structural basis for mechanistic similarities and differences. , 2004, European journal of biochemistry.

[38]  M. Tomita,et al.  Differential Metabolomics Reveals Ophthalmic Acid as an Oxidative Stress Biomarker Indicating Hepatic Glutathione Consumption* , 2006, Journal of Biological Chemistry.

[39]  Andrew Williams,et al.  Methoxyacetic acid-induced spermatocyte death is associated with histone hyperacetylation in rats. , 2008, Biology of reproduction.

[40]  K. Gibson,et al.  Tiglylglycine excreted in urine in disorders of isoleucine metabolism and the respiratory chain measured by stable isotope dilution GC-MS. , 1994, Clinical chemistry.

[41]  H. Bremer,et al.  Glutaric aciduria type II: report on a previously undescribed metabolic disorder. , 1976, Clinica chimica acta; international journal of clinical chemistry.

[42]  R. Cohen.  Reversible subacute ethylene glycol monomethyl ether toxicity associated with microfilm production: a case report. , 1984, American journal of industrial medicine.

[43]  S. Ghisla,et al.  A mechanistic overview , 2004 .

[44]  C. Uhlmann,et al.  A cross-sectional study of ethylene glycol monomethyl ether process employees. , 1982, Archives of environmental health.

[45]  A. Fiorito,et al.  The possible haematological effects of glycol monomethyl ether in a frame factory. , 1992, British journal of industrial medicine.

[46]  K. Kizawa,et al.  Collaborative work on evaluation of ovarian toxicity. 6) Two- or four-week repeated-dose studies and fertility study of cisplatin in female rats. , 2009, The Journal of toxicological sciences.

[47]  R. Chapin,et al.  Protein Kinase Activity Is Central to Rat Germ Cell Apoptosis Induced by Methoxyacetic Acid , 2001, Toxicologic pathology.

[48]  G. Johanson.  Toxicity Review of Ethylene Glycol Monomethyl Ether and its Acetate Ester , 2000, Critical reviews in toxicology.

[49]  E. McCabe,et al.  Multiple Acyl-CoA Dehydrogenase Deficiency (Glutaric Aciduria Type II) with Transient Hypersarcosinemia and Sarcosinuria; Possible Inherited Deficiency of an Electron Transfer Flavoprotein , 1980, Pediatric Research.

[50]  Robert V Farese,et al.  SIRT 3 regulates mitochondrial fatty-acid oxidation by reversible enzyme deacetylation , 2010 .

[51]  J. Vockley,et al.  Short-chain acyl-coenzyme A dehydrogenase deficiency. , 2008, Molecular genetics and metabolism.