| 1. |
- Mukhopadhyay, Rituparna, et al.
(author)
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The Binding Sites for the Chromatin Insulator Protein CTCF Map to DNA Methylation-Free Domains Genome-Wide
- 2004
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In: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 14:8, s. 1594-1602
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Journal article (peer-reviewed)abstract
- All known vertebrate chromatin insulators interact with the highly conserved, multivalent 11-zinc finger nuclear factor CTCF to demarcate expression domains by blocking enhancer or silencer signals in a position-dependent manner. Recent observations document that the properties of CTCF include reading and propagating the epigenetic state of the differentially methylated H19 imprinting control region. To assess whether these findings may reflect a universal role for CTCF targets, we identified more than 200 new CTCF target sites by generating DNA microarrays of clones derived from chromatin-immunopurified (ChIP) DNA followed by ChIP-on-chip hybridization analysis. Target sites include not only known loci involved in multiple cellular functions, such as metabolism, neurogenesis, growth, apoptosis, and signalling, but potentially also heterochromatic sequences. Using a novel insulator trapping assay, we also show that the majority of these targets manifest insulator functions with a continuous distribution of stringency. As these targets are generally DNA methylation-free as determined by antibodies against 5-methylcytidine and a methyl-binding protein (MBD2), a CTCF-based network correlates with genome-wide epigenetic states.
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| 2. |
- Yu, Wenqiang, et al.
(author)
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Poly(ADP-ribosyl)ation regulates CTCF-dependent chromatin insulation
- 2004
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 36:10, s. 1105-1110
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Journal article (peer-reviewed)abstract
- Chromatin insulators demarcate expression domains by blocking the cis effects of enhancers or silencers in a position-dependent manner1, 2. We show that the chromatin insulator protein CTCF carries a post-translational modification: poly(ADP-ribosyl)ation. Chromatin immunoprecipitation analysis showed that a poly(ADP-ribosyl)ation mark, which exclusively segregates with the maternal allele of the insulator domain in the H19 imprinting control region, requires the bases that are essential for interaction with CTCF3. Chromatin immunoprecipitation−on−chip analysis documented that the link between CTCF and poly(ADP-ribosyl)ation extended to more than 140 mouse CTCF target sites. An insulator trap assay showed that the insulator function of most of these CTCF target sites is sensitive to 3-aminobenzamide, an inhibitor of poly(ADP-ribose) polymerase activity. We suggest that poly(ADP-ribosyl)ation imparts chromatin insulator properties to CTCF at both imprinted and nonimprinted loci, which has implications for the regulation of expression domains and their demise in pathological lesions.
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