RT Journal Article
SR Electronic
T1 Regulation of Cytochrome P450 2E1 under Hypertonic Environment through TonEBP in Human Hepatocytes
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 173
OP 181
DO 10.1124/mol.106.033480
VO 72
IS 1
A1 Ito, Takashi
A1 Asakura, Koko
A1 Tougou, Katsuhiko
A1 Fukuda, Tsuyoshi
A1 Kubota, Ryuji
A1 Nonen, Shinpei
A1 Fujio, Yasushi
A1 Azuma, Junichi
YR 2007
UL http://molpharm.aspetjournals.org/content/72/1/173.abstract
AB Whereas the liver as well as the other organs are continually exposed to the change of osmotic status, it has never been investigated whether activities and gene expressions of drug-metabolizing enzymes, including cytochromes P450, are dependent on osmotic change in the liver. In the present study, we determined that CYP2E1 is induced under hypertonic environments at a transcriptional level in human primary hepatocytes, as assessed by cDNA microarray and real time-reverse transcription-polymerase chain reaction analyses. Both a protein level and the catalytic activity of CYP2E1 were consistently increased in response to hypertonic conditions. In promoter-reporter assay, it was demonstrated that -586 to -566 in the CYP2E1 5′-flanking region was necessary for 2E1 promoter activation by hypertonic stimulation. It is noteworthy that tonicity-response element (TonE) consensus sequence was found at -578 to -568 in human CYP2E1 5′-flanking region, and electrophoretic mobility shift assay demonstrated the interaction of TonE binding protein (TonEBP) with TonE motif of CYP2E1 promoter. Furthermore, cotransfection of a CYP2E1 promoter construct with wild-type TonEBP expression vector enhanced promoter activity under both isotonic and hypertonic conditions, whereas dominant-negative TonEBP suppressed an induction of CYP2E1 promoter activity. These results indicate that the level of CYP2E1 is induced by hypertonic condition via TonEBP transactivation. The present study suggests that osmotic status may influence individual responses to the substrate of CYP2E1. The American Society for Pharmacology and Experimental Therapeutics