The human enhancer blocker CTC-binding factor interacts with the transcription factor Kaiso.
CTC-binding factor (CTCF) is a DNA-binding protein of vertebrates that plays essential roles in regulating genome activity through its capacity to act as an enhancer blocker. We performed a yeast two-hybrid screen to identify protein partners of CTCF that could regulate its activity. Using full-length CTCF as bait we recovered Kaiso, a POZ-zinc finger transcription factor, as a specific binding partner. The interaction occurs through a C-terminal region of CTCF and the POZ domain of Kaiso. CTCF and Kaiso are co-expressed in many tissues, and CTCF was specifically co-immunoprecipitated by several Kaiso monoclonal antibodies from nuclear lysates. Kaiso is a bimodal transcription factor that recognizes methylated CpG dinucleotides or a conserved unmethylated sequence (TNGCAGGA, the Kaiso binding site). We identified one consensus unmethylated Kaiso binding site in close proximity to the CTCF binding site in the human 5' beta-globin insulator. We found, in an insulation assay, that the presence of this Kaiso binding site reduced the enhancer-blocking activity of CTCF. These data suggest that the Kaiso-CTCF interaction negatively regulates CTCF insulator activity.
Defossez
Pierre-Antoine
PA
CNRS UMR5161, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France. Defossez@Curie.fr
Kelly
Kevin F
KF
Filion
Guillaume J P
GJ
Pérez-Torrado
Roberto
R
Magdinier
Frédérique
F
Menoni
Hervé
H
Nordgaard
Curtis L
CL
Daniel
Juliet M
JM
Gilson
Eric
E
D000911:Antibodies, Monoclonal / Q000737:chemistry; D001483:Base Sequence; D001665:Binding Sites; D000076246:CCCTC-Binding Factor; D047369:Chromatin Immunoprecipitation; D018899:CpG Islands; D019175:DNA Methylation; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D004742:Enhancer Elements, Genetic; D016678:Genome; D015894:Genome, Human; D005914:Globins / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism / Q000502:physiology*; D013053:Spectrophotometry; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques; D014466:Ultraviolet Rays; D016335:Zinc Fingers
D000911:Antibodies, Monoclonal; D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C492254:ZBTB33 protein, human; D005914:Globins