In vivo transcriptional regulation of N-Myc target genes is controlled by E-box methylation

Proc Natl Acad Sci U S A. 2005 Aug 23;102(34):12117-22. doi: 10.1073/pnas.0409097102. Epub 2005 Aug 10.

Abstract

N-Myc is a transcription factor that forms heterodimers with the protein Max and binds gene promoters by recognizing a DNA sequence, CACGTG, called E-box. The identification of N-myc target genes is an important step for understanding N-Myc biological functions in both physiological and pathological contexts. In this study, we describe the identification of N-Myc-responsive genes through chromatin immunoprecipitation and methylation-sensitive restriction analysis. Results show that N-Myc is a direct regulator of several identified genes, and that methylation of the CpG dinucleotide within the E-box prevents the access of N-Myc to gene promoters in vivo. Furthermore, methylation profile of the E-box within the promoters of EGFR and CASP8, two genes directly controlled by Myc, is cell type-specific, suggesting that differential E-box methylation may contribute to generating unique patterns of Myc-dependent transcription. This study illuminates a central role of DNA methylation in controlling N-Myc occupancy at gene promoters and modulating its transcriptional activity in cancer cells.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism
  • Blotting, Northern
  • Caspase 8
  • Caspases / genetics
  • Cell Line, Tumor
  • Chromatin Immunoprecipitation
  • DNA Methylation*
  • DNA Primers
  • E-Box Elements / genetics
  • E-Box Elements / physiology*
  • Electrophoretic Mobility Shift Assay
  • Gene Expression Regulation, Neoplastic / physiology*
  • Genes, erbB-1 / genetics
  • Humans
  • Immunoblotting
  • Luciferases
  • Promoter Regions, Genetic / genetics
  • Proto-Oncogene Proteins c-myc / genetics
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Repressor Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • DNA Primers
  • MNT protein, human
  • Proto-Oncogene Proteins c-myc
  • Repressor Proteins
  • Transcription Factors
  • Luciferases
  • CASP8 protein, human
  • Caspase 8
  • Caspases