title: Coordinate transcriptional regulation of bile acid homeostasis and drug metabolism.
abstract: Drugs and bile acids are taken up into hepatocytes by specialized transport proteins localized at the basolateral membrane, e.g., organic anion transporting polypeptides . Following intracellular metabolism by cytochrome P450 (CYP) enzymes, drug metabolites are excreted into bile or urine via ATP-dependent multidrug resistance proteins (MDR1 and MRPs). Bile acids are excreted mainly via the bile salt export pump (BSEP, ABCB11). The genes coding for drug and bile acid transporters and CYP enzymes are regulated by a complex network of transcriptional cascades, notably by the ligand-activated nuclear receptors FXR, PXR, and CAR and by the ligand-independent nuclear receptor HNF-4alpha. The bile acid synthesizing enzymes CYP7A1, CYP8B1, and CYP27A1 are subject to negative feedback regulation by bile acids, which is partly mediated through the transcriptional repressor SHP. The role of transcriptional cofactors, such as SRC-1 and PGC-1, in mediating the gene-specific effects of individual nuclear receptors is becoming increasingly evident.
authors.affiliation: Laboratory of Molecular Gastroenterology and Hepatology, Department of Internal Medicine, University Hospital, CH-8091 Zurich, Switzerland.
authors.forename: Jyrki J
authors.initials: JJ
authors.lastname: Eloranta
authors.forename: Gerd A
authors.initials: GA
authors.lastname: Kullak-Ublick
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism*; D053493:Cholestanetriol 26-Monooxygenase; D002790:Cholesterol 7-alpha-Hydroxylase / Q000378:metabolism; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D025461:Feedback, Physiological; D005544:Forecasting; D006360:Heat-Shock Proteins / Q000378:metabolism; D051557:Hepatocyte Nuclear Factor 4; D051548:Histone Acetyltransferases; D006706:Homeostasis; D006801:Humans; D008024:Ligands; D008954:Models, Biological; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D056920:Nuclear Receptor Coactivator 1; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D000077297:Pregnane X Receptor; D018167:Receptors, Calcitriol / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D011987:Receptors, Steroid / Q000378:metabolism; D011991:Receptors, Virus / Q000378:metabolism; D013253:Steroid 12-alpha-Hydroxylase / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D000099150:Receptor, Farnesoid X-Activated
chemical_list: D001647:Bile Acids and Salts; D053493:Cholestanetriol 26-Monooxygenase; D002790:Cholesterol 7-alpha-Hydroxylase; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D003577:Cytochrome P-450 Enzyme System; D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; D051557:Hepatocyte Nuclear Factor 4; D051548:Histone Acetyltransferases; D008024:Ligands; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D056920:Nuclear Receptor Coactivator 1; D004364:Pharmaceutical Preparations; D010750:Phosphoproteins; D000077297:Pregnane X Receptor; D018167:Receptors, Calcitriol; D018160:Receptors, Cytoplasmic and Nuclear; D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D011991:Receptors, Virus; D013253:Steroid 12-alpha-Hydroxylase; D013250:Steroid Hydroxylases; D015534:Trans-Activators; D014157:Transcription Factors; D000099150:Receptor, Farnesoid X-Activated; C568771:CLMP protein, human; C496592:HNF4A protein, human; C111264:peroxisome-proliferator-activated receptor-gamma coactivator-1; C506831:CYP27A1 protein, human; C538859:NCOA1 protein, human