The c-myc insulator element and matrix attachment regions define the c-myc chromosomal domain.
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.
Gombert
Wendy M
WM
Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA 98104, USA.
Farris
Stephen D
SD
Rubio
Eric D
ED
Morey-Rosler
Kristin M
KM
Schubach
William H
WH
Krumm
Anton
A
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
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