Human CCAAT/enhancer-binding protein beta gene expression is activated by endoplasmic reticulum stress through an unfolded protein response element downstream of the protein coding sequence

J Biol Chem. 2004 Jul 2;279(27):27948-56. doi: 10.1074/jbc.M313920200. Epub 2004 Apr 20.

Abstract

CCAAT/enhancer-binding protein beta (C/EBPbeta) is a member of the bZIP family of transcription factors that contribute to the regulation of a wide range of important cellular processes. The data in the present study document that transcription from the human C/EBPbeta gene is induced in response to endoplasmic reticulum stress, such as glucose deprivation, or treatment of cells with tunicamycin or thapsigargin. Transient transfection of C/EBPbeta genomic fragments linked to a luciferase reporter gene demonstrated that the C/EBPbeta promoter plays no major regulatory role. Instead, by deletion analysis it was discovered that a 46-bp region, located at a genomic site that corresponds to the 3'-untranslated region of the C/EBPbeta mRNA, harbored an element that was required for the stress response. Mutagenesis demonstrated that a cis-regulatory element located at nt +1614-1621 (5'-TGACGCAA-3') is responsible for activation of the C/EBPbeta gene. Electrophoresis mobility shift analysis revealed that proteins are bound to this element and that the amount of binding is increased following glucose deprivation. This element is homologous to a previously reported mammalian unfolded protein response element that binds XBP-1. Consistent with those data, overexpression of XBP-1 caused an increase in transcription that was mediated by the C/EBPbeta mammalian unfolded protein response element.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • Binding Sites
  • Blotting, Northern
  • CCAAT-Enhancer-Binding Protein-beta / biosynthesis*
  • Cell Line
  • Cell Line, Tumor
  • Cell Nucleus / metabolism
  • Endoplasmic Reticulum / metabolism*
  • Gene Deletion
  • Gene Expression Regulation*
  • Genes, Reporter
  • Glucose / metabolism
  • Humans
  • Immunoblotting
  • Luciferases / metabolism
  • Models, Genetic
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Protein Folding
  • RNA, Messenger / metabolism
  • Response Elements*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Thapsigargin / pharmacology
  • Time Factors
  • Transcription Factors / metabolism
  • Transcription, Genetic
  • Transcriptional Activation
  • Transfection
  • Tunicamycin / pharmacology

Substances

  • CCAAT-Enhancer-Binding Protein-beta
  • RNA, Messenger
  • Transcription Factors
  • Tunicamycin
  • Thapsigargin
  • Luciferases
  • Glucose