The protein CTCF is required for the enhancer blocking activity of vertebrate insulators.
An insulator is a DNA sequence that can act as a barrier to the influences of neighboring cis-acting elements, preventing gene activation, for example, when located between an enhancer and a promoter. We have identified a 42 bp fragment of the chicken beta-globin insulator that is both necessary and sufficient for enhancer blocking activity in human cells. We show that this sequence is the binding site for CTCF, a previously identified eleven-zinc finger DNA-binding protein that is highly conserved in vertebrates. CTCF sites are present in all of the vertebrate enhancer-blocking elements we have examined. We suggest that directional enhancer blocking by CTCF is a conserved component of gene regulation in vertebrates.
Bell
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Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0540, USA.
West
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Felsenfeld
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D000076246:CCCTC-Binding Factor; D002467:Cell Nucleus / Q000378:metabolism; D002645:Chickens; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D003850:Deoxyribonuclease I; D004742:Enhancer Elements, Genetic; D014644:Genetic Variation; D005914:Globins / Q000235:genetics; D006801:Humans; D020014:K562 Cells; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000378:metabolism; D014176:Protein Biosynthesis; D012097:Repressor Proteins; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014714:Vertebrates; D016335:Zinc Fingers
D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D012097:Repressor Proteins; D014157:Transcription Factors; D005914:Globins; D003850:Deoxyribonuclease I