Identification of CCAAT enhancer binding protein alpha binding sites on the human alpha-fetoprotein gene

Gene. 2007 Mar 15;389(2):128-35. doi: 10.1016/j.gene.2006.10.024. Epub 2006 Nov 11.

Abstract

Development- and tissue-specific alpha-fetoprotein (AFP) gene expression is controlled by various transcription factors including hepatocyte nuclear factors (HNFs), and a number of cis-acting elements. We recently identified multiple CCAAT/enhancer binding protein (C/EBP) binding sites in the enhancer of the human AFP gene. In this study, we have identified and functionally characterized seven C/EBPalpha-binding sites in the promoter and enhancer regions. An electrophoretic mobility shift assay (EMSA) and DNase I footprinting analysis identified two and five C/EBPalpha-binding sites located in the promoter and enhancer regions, respectively. Chromatin immunoprecipitation analyses showed that C/EBPalpha binds both enhancer and promoter regions of the AFP gene in human AFP-producing hepatoma and stomach cancer cells, but not in non-AFP-producing cells. Reporter transfection assays showed that transcription was stimulated by C/EBPalpha binding to each of the elements. These results indicate that C/EBPalpha regulates AFP gene expression through direct binding to multiple sites in the human AFP gene in cultured human cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • CCAAT-Enhancer-Binding Proteins / metabolism*
  • COS Cells
  • Cell Line, Tumor
  • Chlorocebus aethiops
  • Chromatin Immunoprecipitation
  • DNA Footprinting
  • Electrophoretic Mobility Shift Assay
  • Enhancer Elements, Genetic*
  • Gene Expression Regulation
  • Humans
  • Promoter Regions, Genetic*
  • alpha-Fetoproteins / genetics*

Substances

  • CCAAT-Enhancer-Binding Proteins
  • CEBPA protein, human
  • alpha-Fetoproteins