Two novel cis-elements involved in hepatocyte nuclear factor 4α regulation of acyl-coenzyme A：cholesterol acyltransferase 2 expression  

作　　者：Zhuqin Zhang Jinjing Liu Yang Xi Ruifeng Yang Houzao Chen Zhenya Li Depei Liu Chihchuan Liang 

机构地区：[1]National Laboratory of Medical Molecular Biology, Institute of Basic Medical Science, Chinese Academy of Medical Sciences,Beijing 100005, China

出　　处：《Acta Biochimica et Biophysica Sinica》2012年第2期162-171,共10页生物化学与生物物理学报（英文版）

摘　　要：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 ciselements, 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 muta- tion of site II reduced promoter activity to less than onetenth 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 ex- pression at mRNA level. Overexpression of HNF4α increased ACAT2 expression, whereas knockdown of HNF4α decreased ACAT2 expression. Peroxisome prolif- erator-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.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 ciselements, 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 muta- tion of site II reduced promoter activity to less than onetenth 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 ex- pression at mRNA level. Overexpression of HNF4α increased ACAT2 expression, whereas knockdown of HNF4α decreased ACAT2 expression. Peroxisome prolif- erator-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.

关 键 词：ACAT2 gene expression HNF4α PGC1α SHP 

分 类 号：Q513[生物学—生物化学] TQ464.8[化学工程—制药化工]