title: CTCF elements direct allele-specific undermethylation at the imprinted H19 locus.
abstract: The H19 imprinted gene locus is regulated by an upstream 2 kb imprinting control region (ICR) that influences allele-specific expression, DNA methylation, and replication timing. This ICR becomes de novo methylated during late spermatogenesis in the male but emerges from oogenesis in an unmethylated form, and this allele-specific pattern is then maintained throughout early development and in all tissues of the mouse. We have used a genetic approach involving transfection into embryonic stem (ES) cells in order to decipher how the maternal allele is protected from de novo methylation at the time of implantation. Our studies show that CCCTC binding factor (CTCF) boundary elements within the ICR have the ability to prevent de novo methylation on the maternal allele. Since CTCF does not recognize its binding sequence when methylated, this reaction does not occur on the paternal allele, thus preserving the gamete-derived, allele-specific pattern. These results suggest that CTCF may play a general role in the maintenance of differential methylation patterns in vivo.
authors.affiliation: Department of Cellular Biochemistry, Hebrew University Medical School, Ein Kerem, Jerusalem 91120, Israel.
authors.forename: Eyal
authors.initials: E
authors.lastname: Rand
authors.forename: Ittai
authors.initials: I
authors.lastname: Ben-Porath
authors.forename: Ilana
authors.initials: I
authors.lastname: Keshet
authors.forename: Howard
authors.initials: H
authors.lastname: Cedar
mesh_terms: D000483:Alleles; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D000076246:CCCTC-Binding Factor; D002478:Cells, Cultured; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D005260:Female; D018392:Genomic Imprinting / Q000502:physiology*; D019901:Locus Control Region / Q000502:physiology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D010957:Plasmids / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D012737:Sex Factors; D013234:Stem Cells / Q000502:physiology; D014162:Transfection
chemical_list: D000076246:CCCTC-Binding Factor; C000619698:Ctcf protein, mouse; D004268:DNA-Binding Proteins; D012097:Repressor Proteins