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Role of the CLOCK protein in liver detoxification
Author(s) -
Zhao Mengjing,
Zhao Huan,
Deng Jiangming,
Guo Lianxia,
Wu Baojian
Publication year - 2019
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.14828
Subject(s) - circadian clock , detoxification (alternative medicine) , biology , drug metabolism , clock , chromatin immunoprecipitation , biochemistry , microbiology and biotechnology , chemistry , gene expression , metabolism , gene , medicine , alternative medicine , promoter , pathology
Background and Purpose Whether and how circadian clock proteins regulate drug detoxification are not known. Here, we have assessed the effects of CLOCK (a core circadian clock protein) on drug metabolism and detoxification. Experimental Approach Regulation by CLOCK protein of drug‐metabolizing enzymes was assessed using Clock knockout ( Clock −/− ) mice and Hepa‐1c1c7/AML‐12 cells. The relative mRNA and protein levels were determined by qPCR and Western blotting respectively. Toxicity and pharmacokinetic experiments were performed with Clock −/− and wild‐type mice after intraperitoneal injection of coumarin or cyclophosphamide. Transcriptional gene regulation was investigated using luciferase reporter, mobility shift, and chromatin immunoprecipitation (ChIP) assays. Key Results Clock deletion disrupted hepatic diurnal expressions of a number of drug‐metabolizing enzymes in mice. In particular, CYP2A4/5 expressions were markedly down‐regulated, whereas CYP2B10 was up‐regulated. Positive regulation of Cyp2a4/5 and negative regulation of Cyp2b10 by CLOCK were confirmed in Hepa‐1c1c7 and AML‐12 cells. Based on a combination of luciferase reporter, mobility shift, and ChIP assays, we found that CLOCK activated Cyp2a4/5 transcription via specific binding to E‐box elements in promoter region and repressed Cyp2b10 transcription through REV‐ERBα/β (two target genes of CLOCK and transcriptional repressors of Cyp2b10 ). Furthermore, Clock ablation sensitized mice to coumarin toxicity by down‐regulating CYP2A4/5‐mediated metabolism (a detoxification pathway) and to cyclophosphamide toxicity by up‐regulating CYP2B10‐mediated metabolism (generating the toxic metabolite 4‐hydroxycyclophosphamide). Conclusion and Implications CLOCK protein regulates metabolism by the cytochrome P450 family and drug detoxification. The findings improve our understanding of the crosstalk between circadian clock and drug detoxification.