The nuclear receptor REV-ERBα regulates CYP2E1 expression and acetaminophen hepatotoxicity

1. CYP2E1 plays an important role in drug metabolism and drug-induced hepatotoxicity. Here, we aimed to investigate a potential role for the nuclear receptor REV-ERB alpha in regulation of CYP2E1 expression and acetaminophen (APAP)-induced hepatotoxicity, and to determine the underlying mechanisms. 2. Regulatory effects of REV-ERB alpha on CYP2E1 expression were assessed in vivo (using Rev-erb alpha(-/-) mice) and in vitro (using AML12 and HepG2 cells). In vitro microsomal CYP2E1 activity was probed using its specific substrate p-nitrophenol. Pharmacokinetic and acute toxicity studies were performed with Rev-erb alpha(-/-) and wild-type mice after APAP administration. 3. We found that Rev-erb alpha ablation led to decreases in hepatic CYP2E1 expression and activity in mice. In line with this, APAP-induced hepatotoxicity was attenuated in Rev-erb alpha-deficient mice. The attenuated toxicity was due to down-regulation of APAP metabolism mediated by CYP2E1, which was evidenced by a decrease in formation of the toxic intermediate metabolite NAPQI (i.e. reduced APAP-cysteine and APAP-N-acetylcysteine levels). Furthermore, positive regulation of CYP2E1 expression by REV-ERB alpha was confirmed in both AML12 and HepG2 cells. Based on luciferase reporter assays, it was found that REV-ERB alpha regulated Cyp2e1 transcription and expression through repression of DEC2. 4. In conclusion, REV-ERB alpha positively regulates CYP2E1 expression in mice, thereby affecting APAP metabolism and hepatotoxicity.