The essential role of CYP2E1 in metabolism and hepatotoxicity of N,N-dimethylformamide using a novel Cyp2e1 knockout mouse model and a population study
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N,N-Dimethylformamide (DMF) is a widespread contaminant of leather factories and their surrounding environment. There is a lack of direct in vivo evidence supporting CYP2E1 as a primary enzyme responsible for DMF metabolism and hepatotoxicity. In this study, a novel Cyp2e1 knockout (KO) mouse model was generated and used to assess whether DMF metabolism and hepatotoxicity is CYP2E1 dependent using an acute toxicity protocol with a single dose of 1500 mg DMF/kg. An epidemiological study in 698 DMF-exposed workers and 188 non-DMF-exposed controls was conducted to investigate the associations between functional polymorphisms of CYP2E1 (rs6413432/rs2031920) and DMF metabolite (N-methylcarbmoylated-hemoglobin [NMHb]). We successfully established Cyp2e1 KO mice with evidence from DNA sequence analysis, which showed 1-bp insertion at 65 bp (C) site of Cyp2e1 Exon 1. In addition, western blot and in vivo pharmacokinetic study also showed a complete absence of CYP2E1 protein and a 92% and 88% reduction in CYP2E1 activity among males and females, respectively. DMF metabolism as evidenced by increased blood NMHb, and hepatotoxicity as evidenced by elevated liver/body weight ratio, activity of liver enzymes and massive liver necrosis were detected in wild-type (WT) mice but were completely abrogated in KO mice, strongly supporting a CYP2E1-dependent pattern of DMF metabolism and hepatotoxicity. Moreover, variant allele of CYP2E1-rs6413432 was also significantly associated with higher NMHb levels in DMF-exposed workers (P = 0.045). The increase of glucose-regulated protein 94 detected in WT mice but not in KO mice suggested CYP2E1-dependent endoplasmic reticulum stress may be a key mechanism underlying DMF-induced hepatotoxicity.
KeywordsCYP2E1 Knockout (KO) mouse N,N-Dimethylformamide (DMF) Hepatotoxicity Metabolism
This work was supported by the National Natural Science Foundation of China (No. 81372963). We thank Ms Maria Picchi from Lovelace Respiratory Research Institute for scientific editing of the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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