Sequences downstream of the glucocorticoid regulatory element mediate cycloheximide inhibition of steroid induced expression from the rat alpha 1-acid glycoprotein promoter: evidence for a labile transcription factor

Mol Endocrinol. 1988 Dec;2(12):1343-51. doi: 10.1210/mend-2-12-1343.

Abstract

The glucocorticoid induction of alpha 1-acid glycoprotein (AGP) RNA in rat hepatoma cells is diminished by inhibiting protein synthesis. We now show that the AGP 5'-flanking region contains a DNA sequence (position -121 to -107), exhibiting a high degree of homology to the glucocorticoid regulatory element (GRE) consensus sequence ACAXXXTGTTCT, which serves to specifically bind purified rat glucocorticoid receptor in vitro. A 15 base pair oligonucleotide representing the AGP GRE confers glucocorticoid responsiveness on a heterologous promoter; such regulation is not diminished by concurrent inhibition of protein synthesis. However, inclusion of the AGP sequences immediately downstream of the AGP GRE (position -106 to -42) renders the hormonal induction sensitive to inhibition of protein synthesis. Furthermore, inclusion of these downstream sequences results in a more pronounced induction mediated by the AGP GRE. In vitro DNase-1 treatment using nuclear extracts prepared from HTC hepatoma cells generate footprints that indicate the presence of DNA-protein interactions spanning the region from -110 to -68 of the AGP gene. We propose that one or more labile factors acting within this domain, immediately downstream of the GRE, is required for efficient transcription at the AGP promoter.

Publication types

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

MeSH terms

  • Animals
  • Base Sequence
  • Binding Sites / drug effects
  • Cell Line
  • Cycloheximide / antagonists & inhibitors
  • Cycloheximide / pharmacology*
  • Gene Expression Regulation / drug effects*
  • Glucocorticoids / genetics*
  • Glucocorticoids / metabolism
  • Liver Neoplasms / metabolism
  • Liver Neoplasms, Experimental / metabolism
  • Molecular Sequence Data
  • Orosomucoid / genetics*
  • Orosomucoid / metabolism
  • Promoter Regions, Genetic / drug effects*
  • Rats
  • Transcription, Genetic
  • Tumor Cells, Cultured / metabolism

Substances

  • Glucocorticoids
  • Orosomucoid
  • Cycloheximide