PT  - JOURNAL ARTICLE
AU  - Takamitsu Sasaki
AU  - Keita Inami
AU  - Yoshihiro Numata
AU  - Kodai Funakoshi
AU  - Midori Yoshida
AU  - Takeshi Kumagai
AU  - Shuichi Kanno
AU  - Satomi Matsui
AU  - Takayoshi Toriyabe
AU  - Yasushi Yamazoe
AU  - Kouichi Yoshinari
AU  - Kiyoshi Nagata
TI  - Activation of p38 MAPK by clotrimazole led to <em>MRP3</em> activation through a novel transcriptional element
AID  - 10.1124/jpet.115.231589
DP  - 2016 Jan 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - jpet.115.231589
4099  - http://jpet.aspetjournals.org/content/early/2016/08/09/jpet.115.231589.short
4100  - http://jpet.aspetjournals.org/content/early/2016/08/09/jpet.115.231589.full
AB  - Multidrug resistance-associated protein 3 (MRP3) is a basolaterally localized transporter in the liver and contributes to the transport of various metabolites such as conjugates of endogenous compounds and drugs from hepatocytes. MRP3 expression in human livers is low under normal physiological conditions but is induced by drug treatment. Although several studies have identified a region necessary for the basal transcription of MRP3, no region that responds to drugs has been reported. To identify the xenobiotic-responsive elements of MRP3, we constructed a luciferase reporter plasmid containing the MRP3 5′-flanking region up to −10 kb upstream from the transcription start site. Among typical nuclear receptor ligands, clotrimazole dramatically enhanced MRP3 reporter activity in HepG2 cells, while rifampicin had no effect. We then conducted MRP3 reporter assays with deletion or mutation constructs to identify a clotrimazole-responsive element. The element was located approximately −6.8 kb upstream from the MRP3 transcription start site. The overexpression of pregnane X receptor did not enhance the clotrimazole-mediated transcription. We found that clotrimazole was toxic to HepG2 cells and therefore investigated whether mitogen-activated protein kinase (MAPK) activation is involved in the transactivation of MRP3 by clotrimazole. A p38 MAPK inhibitor, SB203580, suppressed MRP3 mRNA expression induced by clotrimazole, while SP600125 (c-Jun N-terminal kinase inhibitor) and PD98059 (extracellular signal-regulated kinase inhibitor) did not. Phosphorylated p38 MAPK was detected in HepG2 cells treated with clotrimazole. These results suggest that activation of the p38 MAPK pathway induces the transcriptional activation of MRP3.