title: Specific sites in the C terminus of CTCF interact with the SA2 subunit of the cohesin complex and are required for cohesin-dependent insulation activity.
abstract: Recent studies have shown that the protein CTCF, which plays an important role in insulation and in large-scale organization of chromatin within the eukaryotic nucleus, depends for both activities on recruitment of the cohesin complex. We show here that the interaction of CTCF with the cohesin complex involves direct contacts between the cohesin subunit SA2 and specific regions of the C-terminal tail of CTCF. All other cohesin components are recruited through their interaction with SA2. Expression in vivo of CTCF mutants lacking the C-terminal domain, or with mutations at sites within it required for SA2 binding, disrupts the normal expression profile of the imprinted genes IGF2-H19 and also results in a loss of insulation activity. Taken together, our results demonstrate that specific sites on the C terminus of CTCF are essential for cohesin binding and insulator function. The only direct interaction between CTCF and cohesin involves contact with SA2, which is external to the cohesin ring. This suggests that in recruiting cohesin to CTCF, SA2 could bind first and the ring could assemble subsequently.
authors: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Tiaojiang
authors: T
authors: Xiao
authors: Julie
authors: J
authors: Wallace
authors: Gary
authors: G
authors: Felsenfeld
mesh_terms: D034961:Antigens, Nuclear / Q000378:metabolism*; D001665:Binding Sites; D000076246:CCCTC-Binding Factor; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D015870:Gene Expression; D018392:Genomic Imprinting; D006367:HeLa Cells; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics; D009154:Mutation; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000235:genetics; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D000097722:Cohesins
chemical_list: D034961:Antigens, Nuclear; D000076246:CCCTC-Binding Factor; D018797:Cell Cycle Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D007335:Insulin-Like Growth Factor II; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D012097:Repressor Proteins; D000097722:Cohesins; C000619697:CTCF protein, human; C094335:H19 long non-coding RNA; C035170:IGF2 protein, human; C508565:STAG2 protein, human