title: The c-myc insulator element and matrix attachment regions define the c-myc chromosomal domain.
abstract: Insulator elements and matrix attachment regions are essential for the organization of genetic information within the nucleus. By comparing the pattern of histone modifications at the mouse and human c-myc alleles, we identified an evolutionarily conserved boundary at which the c-myc transcription unit is separated from the flanking condensed chromatin enriched in lysine 9-methylated histone H3. This region harbors the c-myc insulator element (MINE), which contains at least two physically separable, functional activities: enhancer-blocking activity and barrier activity. The enhancer-blocking activity is mediated by CTCF. Chromatin immunoprecipitation assays demonstrate that CTCF is constitutively bound at the insulator and at the promoter region independent of the transcriptional status of c-myc. This result supports an architectural role of CTCF rather than a regulatory role in transcription. An additional higher-order nuclear organization of the c-myc locus is provided by matrix attachment regions (MARs) that define a domain larger than 160 kb. The MARs of the c-myc domain do not act to prevent the association of flanking regions with lysine 9-methylated histones, suggesting that they do not function as barrier elements.
authors.affiliation: Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA 98104, USA.
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Gombert
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Farris
authors.forename: Eric D
authors.initials: ED
authors.lastname: Rubio
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Morey-Rosler
authors.forename: William H
authors.initials: WH
authors.lastname: Schubach
authors.forename: Anton
authors.initials: A
authors.lastname: Krumm
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D000076246:CCCTC-Binding Factor; D002460:Cell Line; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism; D002877:Chromosomes, Human / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D016259:Genes, myc; D018922:HL-60 Cells; D006657:Histones / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D008745:Methylation; D051379:Mice; D015530:Nuclear Matrix / Q000378:metabolism; D011485:Protein Binding; D012097:Repressor Proteins; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D002843:Chromatin; C000619698:Ctcf protein, mouse; D004268:DNA-Binding Proteins; D006657:Histones; D012097:Repressor Proteins; D014157:Transcription Factors; D004247:DNA