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Drug Metab Dispos. 2018 Jan;46(1):46-52. doi: 10.1124/dmd.117.077693. Epub 2017 Nov 3.

Tripartite Motif Containing 24 Acts as a Novel Coactivator of the Constitutive Active/Androstane Receptor.

Author information

1
Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan ykanno@phar.toho-u.ac.jp.
2
Department of Molecular Toxicology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan.

Abstract

The constitutive androstane receptor (CAR) is a nuclear receptor that acts as a transcription factor for a variety of genes, including genes encoding xenobiotic, steroid, and drug-metabolizing enzymes and transporters. Transactivation of a target gene by a transcription factor is generally mediated through the concerted and stepwise recruitment of various proteins termed coregulators, including coactivators and corepressors. In this study, TRIM24 (also known as transcriptional intermediary factor 1 alpha) was found to interact with the CAR. TRIM24 enhanced the CAR-dependent transactivation in reporter assays using the direct repeat-4 motif, a binding site of the CAR. This enhancement was synergistically augmented in the presence of steroid receptor coactivator (SRC) 1 or SRC2, both of which are coactivators of the CAR. In addition, TRIM24 was recruited to the CAR-binding element of the CYP2B6 promoter together with the CAR. We also noted that knockdown of TRIM24 suppressed CAR-induced CYP2B6 mRNA expression in HepTR/CAR and HepaRG cells and suppressed CAR-induced CYP3A4 mRNA expression in HepaRG cells but not HepTR/CAR cells. From these results, we suggest that TRIM24 is a novel coactivator of the CAR that is involved in cell- and/or promoter- selective transactivation.

PMID:
29101097
DOI:
10.1124/dmd.117.077693
[Indexed for MEDLINE]

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