Sox-Oct motifs contribute to maintenance of the unmethylated H19 ICR in YAC transgenic mice

Hum Mol Genet. 2013 Nov 15;22(22):4627-37. doi: 10.1093/hmg/ddt311. Epub 2013 Jul 2.

Abstract

Abnormal methylation at the maternally inherited H19 imprinted control region (H19 ICR) is one of the causative alterations leading to pathogenesis of Beckwith-Wiedemann syndrome (BWS). Recently, it was shown in human BWS patients, as well as mouse cell culture experiments, that Sox-Oct motifs (SOM) in the H19 ICR might play a role in protecting the maternal ICR from de novo DNA methylation. By grafting a mouse H19 ICR fragment into a human β-globin yeast artificial chromosome (YAC) followed by analysis in transgenic mice (TgM), we showed previously that the fragment carried sufficient information to establish and maintain differential methylation after fertilization. To examine possible functions of the SOM in the establishment and/or maintenance of differential methylation, two kinds of YAC-TgM were generated in this study. In the ΔSOM TgM, carrying the mouse H19 ICR bearing an SOM deletion, a maternally inherited transgenic ICR exhibited increased levels of methylation around the deletion site, in comparison to the wild-type control, after implantation. In the λ + CTCF + b (LCb) TgM, carrying a 2.3 kb λ DNA fragment supplemented with the fragment b including the SOM and four CTCF binding sites, maternally and some of the paternally inherited LCb fragments were significantly less methylated when compared with a control λ + CTCF fragment that was supplemented only with additional CTCF sites; the λ + CTCF was substantially methylated regardless of the parent of origin after implantation. These results demonstrated that the SOM in the maternal H19 ICR was required for maintaining surrounding sequences in the unmethylated state in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Amino Acid Motifs*
  • Animals
  • Beckwith-Wiedemann Syndrome / genetics*
  • CCCTC-Binding Factor
  • Chromosomes, Artificial, Yeast / genetics*
  • DNA Methylation
  • Female
  • Genomic Imprinting*
  • Humans
  • Insulin-Like Growth Factor II / genetics*
  • Insulin-Like Growth Factor II / metabolism
  • Locus Control Region*
  • Male
  • Mice
  • Mice, Inbred ICR
  • Mice, Transgenic
  • Pedigree
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • beta-Globins / genetics

Substances

  • CCCTC-Binding Factor
  • CTCF protein, human
  • Ctcf protein, mouse
  • Repressor Proteins
  • beta-Globins
  • Insulin-Like Growth Factor II