We gather together: insulators and genome organization.
When placed between an enhancer and promoter, certain DNA sequence elements inhibit enhancer-stimulated gene expression. The best characterized of these enhancer-blocking insulators, gypsy in Drosophila and the CTCF-binding element in vertebrates and flies, stabilize contacts between distant genomic regulatory sites leading to the formation of loop domains. Current results show that CTCF mediates long-range contacts in the mouse beta-globin locus and at the Igf2/H19-imprinted locus. Recently described active chromatin hubs and transcription factories also involve long-range interactions; it is likely that CTCF interferes with their formation when acting as an insulator. The properties of CTCF, and its newly described genomic distribution, suggest that it may play an important role in large-scale nuclear architecture, perhaps mediated by the co-factors with which it interacts in vivo.
Wallace
Julie A
JA
Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892-0540, United States.
Felsenfeld
Gary
G
D000818:Animals; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism; D002875:Chromosomes / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D016678:Genome / Q000502:physiology*; D006801:Humans; D038101:Insulator Elements / Q000502:physiology*; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D002843:Chromatin; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors