PMID- 16882880 OWN - NLM STAT- MEDLINE DCOM- 20061204 LR - 20161124 IS - 0026-895X (Print) IS - 0026-895X (Linking) VI - 70 IP - 5 DP - 2006 Nov TI - Transcriptional activation of CYP2C9, CYP1A1, and CYP1A2 by hepatocyte nuclear factor 4alpha requires coactivators peroxisomal proliferator activated receptor-gamma coactivator 1alpha and steroid receptor coactivator 1. PG - 1681-92 AB - Hepatocyte nuclear factor 4alpha (HNF4alpha) is a key transcription factor for the constitutive expression of cytochromes P450 (P450s) in the liver. However, human hepatoma HepG2 cells show a high level of HNF4alpha but express only marginal P450 levels. We found that the HNF4alpha-mediated P450 transcription in HepG2 is impaired by the low level of coactivators peroxisomal proliferator activated receptor-gamma coactivator 1alpha (PGC1alpha) and steroid receptor coactivator 1 (SRC1). Reporter assays with a chimeric CYP2C9-LUC construct demonstrated that the sole transfection of coactivators induced luciferase activity in HepG2 cells. In HeLa cells however, CYP2C9-LUC activity only significantly increased when coactivators were cotransfected with HNF4alpha. A deletion mutant lacking the two proximal HNF4alpha binding sites in the CYP2C9 promoter did not respond to PGC1alpha or SRC1, demonstrating that coactivators were acting through HNF4alpha response elements. Adenovirus-mediated transfection of PGC1alpha in human hepatoma cells caused a significant dose-dependent increase in CYP2C9, CYP1A1, and CYP1A2 and in the positive control CYP7A1. PGC1alpha also showed a moderate activating effect on CYP3A4, CYP3A5, and CYP2D6. Adenoviral transfection of SRC1 had a lessened effect on P450 genes. Chromatin immunoprecipitation assay demonstrated in vivo binding of HNF4alpha and PGC1alpha to HNF4alpha response sequences in the CYP2C9 promoter and to three new regulatory regions in the common 23.3 kilobase spacer sequence of the CYP1A1/2 cluster. Insulin treatment of HepG2 and human hepatocytes caused repression of PGC1alpha and a concomitant down-regulation of P450s. Our results establish the importance of coactivators PGC1alpha and SRC1 for the hepatic expression of human P450s and uncover a new HNF4alpha-dependent regulatory mechanism to constitutively control the CYP1A1/2 cluster. FAU - Martinez-Jimenez, Celia P AU - Martinez-Jimenez CP AD - Unidad de Hepatologia Experimental, Centro de Investigacion, Hospital La Fe, Avenida de Campanar, 21, 46009 Valencia, Spain. FAU - Castell, Jose V AU - Castell JV FAU - Gomez-Lechon, M Jose AU - Gomez-Lechon MJ FAU - Jover, Ramiro AU - Jover R LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20060801 PL - United States TA - Mol Pharmacol JT - Molecular pharmacology JID - 0035623 RN - 0 (Heat-Shock Proteins) RN - 0 (Hepatocyte Nuclear Factor 4) RN - 0 (Insulin) RN - 0 (PPARGC1A protein, human) RN - 0 (Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha) RN - 0 (Transcription Factors) RN - EC 1.14.13.- (CYP2C9 protein, human) RN - EC 1.14.13.- (Cytochrome P-450 CYP2C9) RN - EC 1.14.14.1 (Aryl Hydrocarbon Hydroxylases) RN - EC 1.14.14.1 (Cytochrome P-450 CYP1A1) RN - EC 1.14.14.1 (Cytochrome P-450 CYP1A2) RN - EC 2.3.1.48 (Histone Acetyltransferases) RN - EC 2.3.1.48 (NCOA1 protein, human) RN - EC 2.3.1.48 (Nuclear Receptor Coactivator 1) SB - IM MH - Adenoviridae/metabolism MH - Aryl Hydrocarbon Hydroxylases/*genetics MH - Cells, Cultured MH - Cytochrome P-450 CYP1A1/*genetics MH - Cytochrome P-450 CYP1A2/*genetics MH - Cytochrome P-450 CYP2C9 MH - Female MH - HeLa Cells MH - Heat-Shock Proteins/genetics/*metabolism MH - Hepatocyte Nuclear Factor 4/genetics/*metabolism MH - Hepatocytes/drug effects MH - Histone Acetyltransferases/genetics/*metabolism MH - Humans MH - Insulin/pharmacology MH - Male MH - Middle Aged MH - Nuclear Receptor Coactivator 1 MH - Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha MH - Protein Binding/drug effects MH - Response Elements/genetics MH - Transcription Factors/genetics/*metabolism MH - *Transcriptional Activation/drug effects MH - Transfection EDAT- 2006/08/03 09:00 MHDA- 2006/12/09 09:00 CRDT- 2006/08/03 09:00 PHST- 2006/08/03 09:00 [pubmed] PHST- 2006/12/09 09:00 [medline] PHST- 2006/08/03 09:00 [entrez] AID - mol.106.025403 [pii] AID - 10.1124/mol.106.025403 [doi] PST - ppublish SO - Mol Pharmacol. 2006 Nov;70(5):1681-92. doi: 10.1124/mol.106.025403. Epub 2006 Aug 1.