RT Journal Article
SR Electronic
T1 Activated Sterol Regulatory Element-Binding Protein-2 Suppresses Hepatocyte Nuclear Factor-4-Mediated <em>Cyp3a11</em> Expression in Mouse Liver
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP mol.110.068577
DO 10.1124/mol.110.068577
A1 Shin-ichi Inoue
A1 Kouichi Yoshinari
A1 Mika Sugawara
A1 Yasushi Yamazoe
YR 2010
UL http://molpharm.aspetjournals.org/content/early/2010/10/12/mol.110.068577.abstract
AB Sterol regulatory element-binding protein-2 (SREBP-2) is a key transcription factor for the cholesterol homeostasis. Recent studies have suggested the association of CYP3A enzymes, major drug-metabolizing enzymes, with cholesterol metabolism. In the present study, we have investigated a possible involvement of SREBP-2 in hepatic Cyp3a11 expression. Feeding a low-cholesterol diet (LCD) to mice activated hepatic SREBP-2 while it attenuated hepatic Cyp3a11 expression. These phenomena were reversed by cholesterol supplementation to LCD. In reporter assays, the overexpression of constitutively active SREBP-2 reduced Cyp3a11 reporter activity through the region from -1581 to -1570 of Cyp3a11. This region contained a putative hepatocyte nuclear factor-4α (HNF-4α)-binding motif, and HNF-4α, but not SREBP-2, bound to the motif in in vitro binding assays. With the mutation or deletion of this motif, the SREBP-2-dependent suppression of Cyp3a11 expression disappeared in reporter assays. In pull-down assays and co-immunoprecipitation assays, SREBP-2 bound to peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a major coactivator for HNF-4α, via its transactivation domain and inhibited the interaction between HNF-4α and PGC-1α in vitro. Consistently, a mutant SREBP-2 lacking the transactivation domain did not reduce Cyp3a11 reporter activity. Furthermore, PGC-1α overexpression relieved the SREBP-2-mediated reduction of Cyp3a11 reporter activity. Finally, chromatin immunoprecipitation assays demonstrated that the extent of PGC-1α binding to the Cyp3a11 promoter was reduced by LCD-feeding in mouse livers. In conclusion, activated SREBP-2 interacts with PGC-1α in mouse livers at reduced cholesterol intake. This results in the reduced PGC-1α recruitment to HNF-4α on the Cyp3a11 promoter and the subsequent down-regulation of Cyp3a11 expression.