title: Involvement of corepressor complex subunit GPS2 in transcriptional pathways governing human bile acid biosynthesis.
abstract: Coordinated regulation of bile acid biosynthesis, the predominant pathway for hepatic cholesterol catabolism, is mediated by few key nuclear receptors including the orphan receptors liver receptor homolog 1 (LRH-1), hepatocyte nuclear factor 4alpha (HNF4alpha), small heterodimer partner (SHP), and the bile acid receptor FXR (farnesoid X receptor). Activation of FXR initiates a feedback regulatory loop via induction of SHP, which suppresses LRH-1- and HNF4alpha-dependent expression of cholesterol 7alpha hydroxylase (CYP7A1) and sterol 12alpha hydroxylase (CYP8B1), the two major pathway enzymes. Here we dissect the transcriptional network governing bile acid biosynthesis in human liver by identifying GPS2, a stoichiometric subunit of a conserved corepressor complex, as a differential coregulator of CYP7A1 and CYP8B1 expression. Direct interactions of GPS2 with SHP, LRH-1, HNF4alpha, and FXR indicate alternative coregulator recruitment strategies to cause differential transcriptional outcomes. In addition, species-specific differences in the regulation of bile acid biosynthesis were uncovered by identifying human CYP8B1 as a direct FXR target gene, which has implications for therapeutic approaches in bile acid-related human disorders.
authors: Department of Biosciences and Nutrition, Karolinska Institutet, Karolinska University Hospital, S-14157 Huddinge, Sweden. sabyasachi.sanyal@biosci.ki.se
authors: Sabyasachi
authors: S
authors: Sanyal
authors: Ann
authors: A
authors: Båvner
authors: Anna
authors: A
authors: Haroniti
authors: Lisa-Mari
authors: LM
authors: Nilsson
authors: Thomas
authors: T
authors: Lundåsen
authors: Stefan
authors: S
authors: Rehnmark
authors: Michael Robin
authors: MR
authors: Witt
authors: Curt
authors: C
authors: Einarsson
authors: Iannis
authors: I
authors: Talianidis
authors: Jan-Ake
authors: JA
authors: Gustafsson
authors: Eckardt
authors: E
authors: Treuter
mesh_terms: D001647:Bile Acids and Salts / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular; D045744:Cell Line, Tumor; D002790:Cholesterol 7-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008113:Liver Neoplasms; D011401:Promoter Regions, Genetic; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D013253:Steroid 12-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D000099150:Receptor, Farnesoid X-Activated
chemical_list: D001647:Bile Acids and Salts; D002790:Cholesterol 7-alpha-Hydroxylase; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D013253:Steroid 12-alpha-Hydroxylase; D014157:Transcription Factors; D000099150:Receptor, Farnesoid X-Activated; C103316:GPS2 protein, human