Premium
PGC‐1α regulates both the constitutive and drug‐inducible expression of human CYP2C9
Author(s) -
CHEN YUPING,
GOLDSTEIN JOYCE A.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a260-a
Subject(s) - chromatin immunoprecipitation , coactivator , glucocorticoid receptor , transcription factor , microbiology and biotechnology , chemistry , biology , pharmacology , promoter , receptor , gene expression , gene , biochemistry
CYP2C9 is an important human drug‐metabolizing enzyme primarily expressed in liver. It metabolizes numerous prescribed drugs including oral antidiabetics tolbutamide, antiepileptics phenytoin, the anticoagulant warfarin and many non‐steroid anti inflammatory drugs. It is known that CYP2C9 is drug inducible via the transcriptional regulation by various nuclear receptors including CAR, PXR and GR. Here we show that PGC‐1α, a coactivator involved in energy metabolism, greatly upregulates CYP2C9 promoter activity in HepG2 cells via its coactivation of HNF4α. Through EMSA, deletion and mutagenesis assays, we have identified three DR1 type elements at −152, −185 and −218 as HNF4alpha binding sites. Mutation of either the −152 site or the −185 site completely abolished PGC‐1alpha activation, while disrupt of the −218 site resulted in about 60% loss of this activation. Cotransfection of different amounts of the dominant negative HNF4α decreased promoter activity gradually, while PGC‐1α activation was abolished very effectively with each dose. Chromatin immunoprecipitation assays demonstrated that both PGC‐1α and HNF4α are precipitated in the CYP2C9 promoter region harboring three HNF4α sites. We also show here that PGC‐1α coactivated hGR to dramatically increase hGR‐mediated dexamethasone induction of CYP2C9 . Mutation of HNF4α sites did not effect induction of dexamethasone mediated induction either by GR alone or together with coactivation of PGC‐1α. However, overexpression of HNF4α led a suppression in dexamethasone induction, possibly due to competition between GR and HNF4α for coactivators. These studies suggest that CYP2C9 may be one target of PGC‐1α. This research was supported by the intramural division of the NIEHS.