title: Two novel cis-elements involved in hepatocyte nuclear factor 4α regulation of acyl-coenzyme A:cholesterol acyltransferase 2 expression.
abstract: Acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT2) is important for cholesterol ester synthesis and secretion. A previous study revealed that ACAT2 gene promoter activity was upregulated by hepatocyte nuclear factor 4α (HNF4α) through two sites around -247 and -311 of ACAT2 gene promoter. Here, we identified two novel cis-elements, site I (-1006 to -898) and site II (-38 to -29), which are important for HNF4α effect. In HepG2 cells, mutation of site I decreased ACAT2 gene promoter activity to one-fifth of that of the wild type, while mutation of site II reduced promoter activity to less than one-tenth of that of the wild type. In 293T cells, mutation of these two cis-elements profoundly impaired the HNF4α induction effect. When either of these two elements was inserted into pGL3-promoter, HNF4α induced promoter activity through the inserted element, while mutation of the element impaired HNF4α induction effect. In electrophoretic mobility shift assay and chromatin immunoprecipitation experiment, HNF4α bound to these two elements. Thus, the two cis-elements are important for HNF4α effect on ACAT2 gene transcription. We also showed that HNF4α positively regulates ACAT2 gene expression at mRNA level. Overexpression of HNF4α increased ACAT2 expression, whereas knockdown of HNF4α decreased ACAT2 expression. Peroxisome proliferator-activated receptor gamma coactivator 1α (PCG1α), a coactivator of HNF4α, increased ACAT2 expression, while small heterodimer partner (SHP), a corepressor of HNF4α, decreased ACAT2 expression. These results provide more insights into transcriptional regulation of ACAT2 expression.
authors.affiliation: National Laboratory of Medical Molecular Biology, Institute of Basic Medical Science, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Zhuqin
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jinjing
authors.initials: J
authors.lastname: Liu
authors.forename: Yang
authors.initials: Y
authors.lastname: Xi
authors.forename: Ruifeng
authors.initials: R
authors.lastname: Yang
authors.forename: Houzao
authors.initials: H
authors.lastname: Chen
authors.forename: Zhenya
authors.initials: Z
authors.lastname: Li
authors.forename: Depei
authors.initials: D
authors.lastname: Liu
authors.forename: Chihchuan
authors.initials: C
authors.lastname: Liang
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D055785:Gene Knockdown Techniques; D005816:Genetic Complementation Test; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D056945:Hep G2 Cells; D051557:Hepatocyte Nuclear Factor 4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D002785:Sterol O-Acyltransferase / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000097587:Sterol O-Acyltransferase 2
chemical_list: D017931:DNA Primers; D006360:Heat-Shock Proteins; D051557:Hepatocyte Nuclear Factor 4; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012333:RNA, Messenger; D002785:Sterol O-Acyltransferase; D014157:Transcription Factors; D000097587:Sterol O-Acyltransferase 2; C496592:HNF4A protein, human; C486497:PPARGC1A protein, human