Identification of an histone H3 acetylated/K4-methylated-bound intragenic enhancer regulatory for urokinase receptor expression

Oncogene. 2007 Mar 29;26(14):2058-70. doi: 10.1038/sj.onc.1210003. Epub 2006 Sep 25.

Abstract

The transcriptionally regulated urokinase-type plasminogen activator receptor (u-PAR) contributes to cancer progression. Although previous studies have identified multiple 5' regulatory elements, these cis motifs cannot fully account for u-PAR expression prompting a search for hitherto uncharacterized regulatory elements. DNase I hypersensitivity and chromatin immunoprecipitation assays using u-PAR-expressing colon cancer cells indicated a hypersensitive region (+665/+2068) in intron 1 enriched with acetylated histone 3 (H3) and H3 methylated at lysine 4, markers of regulatory regions. The +665/+2068 region increased transcription from a u-PAR-promoter in an orientation- and distance-independent manner fulfilling the criteria of an enhancer. Optimal stimulation of the u-PAR promoter by phorbol ester required this enhancer. Systematic truncations combined with DNase I footprinting revealed two protected regions (+1060/+1099 and +1123/+1134) with deletion of the latter practically abolishing enhancer activity. The +1123/+1134 region harbored non-consensus activator protein-1 and Ets1 binding sites bound with c-Jun (and/or the related JunD/JunB) and c-Fos (and/or the related FosB/Fra-1/Fra-2) as revealed with chromatin immunoprecipitation. Further, nuclear extract from resected colon cancers showed elevated protein binding to a +1123/+1134-spanning probe coordinate with elevated u-PAR protein. Thus, we have defined a novel intragenic enhancer in the u-PAR gene required for constitutive and inducible expression.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acetylation
  • Chromatin / metabolism
  • Chromatin Immunoprecipitation
  • Colonic Neoplasms / genetics
  • DNA Footprinting
  • Deoxyribonuclease I / chemistry
  • Enhancer Elements, Genetic*
  • Gene Expression Regulation, Neoplastic*
  • Histones / metabolism
  • Humans
  • Introns
  • Promoter Regions, Genetic
  • Receptors, Cell Surface / genetics*
  • Receptors, Cell Surface / metabolism
  • Receptors, Urokinase Plasminogen Activator
  • Transcription Factors / metabolism

Substances

  • Chromatin
  • Histones
  • PLAUR protein, human
  • Receptors, Cell Surface
  • Receptors, Urokinase Plasminogen Activator
  • Transcription Factors
  • Deoxyribonuclease I