Insertional chromatin immunoprecipitation: a method for isolating specific genomic regions.

Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
Journal of Bioscience and Bioengineering (Impact Factor: 1.74). 11/2009; 108(5):446-9. DOI: 10.1016/j.jbiosc.2009.05.005
Source: PubMed

ABSTRACT We established a novel method, insertional chromatin immunoprecipitation (iChIP), for isolation of specific genomic regions. In iChIP, specific genomic domains are immunoprecipitated with antibody against a tag, which is fused to the DNA-binding domain of an exogenous DNA-binding protein, whose recognition sequence is inserted into the genomic domains of interest. The iChIP method will be a useful tool for dissecting chromatin structure of genomic region of interest.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Isolation of specific genomic regions retaining molecular interactions is essential for comprehensive identification of molecules associated with the genomic regions. Recently, we developed the engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) technology for purification of specific genomic regions. Here, we developed a retroviral expression system for enChIP using CRISPR. We showed that the target genomic locus can be purified with high efficiency by using this system. We also showed that contamination of potential off-target sites is negligible by using this system if the guide RNA (gRNA) for the target site has a sufficiently long unique sequence in its seed sequence. enChIP combined with stable isotope labeling using amino acids in cell culture (SILAC) analysis identified proteins whose association with the interferon (IFN) regulatory factor-1 (IRF-1) promoter region increases in response to IFNγ stimulation. The list of the associated proteins contained many novel proteins in the context of IFNγ-induced gene expression as well as proteins related to histone deacetylase complexes whose involvement has been suggested in IFNγ-mediated gene expression. Finally, we confirmed IFNγ-induced increased association of the identified proteins with the IRF-1 promoter by ChIP. Thus, our results showed that the retroviral enChIP system using CRISPR would be useful for biochemical analysis of genome functions including transcription and epigenetic regulation.
    PLoS ONE 01/2014; 9(7):e103084. · 3.73 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Here, we describe an approach to isolate native chromatin sections without genomic engineering for label-free proteomic identification of associated proteins and histone post-translational modifications. A transcription activator-like (TAL) protein A fusion protein was designed to recognize a unique site in the yeast GAL1 promoter. The TAL-PrA fusion enabled chromatin affinity purification (ChAP) of a small section of native chromatin upstream from the GAL1 locus, permitting mass spectrometric (MS) identification of proteins and histone post-translational modifications regulating galactose-induced transcription. This TAL-ChAP-MS approach allows the biochemical isolation of a specific native genomic locus for proteomic studies and will provide for unprecedented objective insight into protein and epigenetic mechanisms regulating site-specific chromosome metabolism.
    Nucleic Acids Research 09/2013; · 8.81 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: Comprehensive understanding of mechanisms of genome functions requires identification of molecules interacting with genomic regions of interest in vivo. We have developed the insertional chromatin immunoprecipitatin (iChIP) technology to isolate specific genomic regions retaining molecular interactions and identify their associated molecules. iChIP consists of locus-tagging and affinity purification. The recognition sequences of an exogenous DNA-binding protein such as LexA are inserted into a genomic region of interest in the cell to be analyzed. The exogenous DNA-binding protein fused with a tag(s) is expressed in the cell and the target genomic region is purified with antibody against the tag(s). In this study, we developed the iChIP system using recombinant DNA-binding proteins to make iChIP more straightforward. Results: In this system, recombinant 3xFNLDD-D (r3xFNLDD-D) consisting of the 3xFLAG-tag, a nuclear localization signal, the DNA-binding domain plus the dimerization domain of the LexA protein, and the Dock-tag is used for isolation of specific genomic regions. 3xFNLDD-D was expressed using a silkworm-baculovirus expression system and purified by affinity purification. iChIP using r3xFNLDD-D could efficiently isolate the single-copy chicken Pax5 (cPax5) locus, in which LexA binding elements were inserted, with negligible contamination of other genomic regions. In addition, we could detect RNA associated with the cPax5 locus using this form of the iChIP system combined with RT-PCR. Conclusions: The iChIP system using r3xFNLDD-D can isolate specific genomic regions retaining molecular interactions without expression of the exogenous DNA-binding protein in the cell to be analyzed. iChIP using r3xFNLDD-D would be more straightforward and useful for analysis of specific genomic regions to elucidate their functions.


Available from
May 27, 2014