出版社：American Society for Biochemistry and Molecular Biology
摘要：ACAT catalyzes the formation of cholesteryl esters from cholesteroland long-chain fatty acids. There are two known genes encodingthe two ACAT enzymes, ACAT1 and ACAT2 (also known as Soat1 andSoat2). In adult humans, ACAT1 is present in most tissues, whereasACAT2 is localized to enterocytes and hepatocytes. In this report,we elucidate the mechanisms that control the liver-specificexpression of the human ACAT2 gene. We identified hepatic nuclearfactor 1 (HNF1) as an important liver-specific trans-actingelement for the human ACAT2 gene using the human hepatocellularcarcinoma cell lines HuH7 and HepG2. Targeted deletion of theHNF1 binding site in the DNA sequence abolished not only thebasal promoter function in HepG2 and HuH7 cells but also theinduction of the ACAT2 promoter by HNF1. Electrophoretic mobilityshift assay and chromatin immunoprecipitation assay demonstratedthat the transcription factors HNF1 and HNF1ß interactwith this region in the human ACAT2 gene in vitro and in vivo.
These data indicate that a) the identified HNF1 binding siteserves as a positive regulator sequence, b) the binding siteis functionally active both in vivo and in vitro, and c) thetranscription factors HNF1 and HNF1ß, which bind tothis site, play an important part in the regulation of the humanACAT2 promoter.Abbreviations: Cdx-2, caudal-related homeodomain protein-2; C/EBP, CCAAT/enhancer binding protein; ChIP, chromatin immunoprecipitation assay; EMSA, electrophoretic mobility shift assay; HNF1, hepatic nuclear factor 1; MODY, maturity-onset diabetes of the young; TESS, transcription element search software
Supplementary key words liver • cholesterol • transcription factor • gene regulation • metabolism • acyl-coenzyme A:cholesterol acyltransferase • hepatic nuclear factor 1
and HNF1ß interact with this region in the human ACAT2 gene in vitro and in vivo.
These data indicate that a) the identified HNF1 binding site serves as a positive regulator sequence, b) the binding site is functionally active both in vivo and in vitro, and c) the transcription factors HNF1
