Dataset Information

Trac-looping measures genome structure and chromatin accessibility.

ABSTRACT: Long-range chromatin interactions play critical roles in genome organization and regulation of transcription. We now report transposase-mediated analysis of chromatin looping (Trac-looping) for simultaneous detection of multiscale genome-wide chromatin interactions among regulatory elements and chromatin accessibility. With this technique, a bivalent oligonucleotide linker is inserted between two interacting regions such that the chromatin interactions are captured without prior chromatin fragmentation and proximity-based ligation. Application of Trac-looping to human CD4+ T cells revealed substantial reorganization of enhancer-promoter interactions associated with changes in gene expression after T cell receptor stimulation.

SUBMITTER: Lai B

PROVIDER: S-EPMC7212307 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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Trac-looping measures genome structure and chromatin accessibility.

Lai Binbin B Tang Qingsong Q Jin Wenfei W Hu Gangqing G Wangsa Darawalee D Cui Kairong K Stanton Benjamin Z BZ Ren Gang G Ding Yi Y Zhao Ming M Liu Shuai S Song Jiuzhou J Ried Thomas T Zhao Keji K

Nature methods 20180827 9

Long-range chromatin interactions play critical roles in genome organization and regulation of transcription. We now report transposase-mediated analysis of chromatin looping (Trac-looping) for simultaneous detection of multiscale genome-wide chromatin interactions among regulatory elements and chromatin accessibility. With this technique, a bivalent oligonucleotide linker is inserted between two interacting regions such that the chromatin interactions are captured without prior chromatin fragme ...[more]

PMID: 30150754

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Project description:The challenge in extracting genome-wide chromatin features from limiting clinical samples poses a significant hurdle in identification of regulatory marks that impact the physiological or pathological state. Current methods that identify nuclease accessible chromatin are reliant on large amounts of purified nuclei as starting material. This complicates analysis of trace clinical tissue samples that are often stored frozen. We have developed an alternative nuclease based procedure to bypass nuclear preparation to interrogate nuclease accessible regions in frozen tissue samples.Here we introduce a novel technique that specifically identifies Tissue Accessible Chromatin (TACh). The TACh method uses pulverized frozen tissue as starting material and employs one of the two robust endonucleases, Benzonase or Cyansase, which are fully active under a range of stringent conditions such as high levels of detergent and DTT. As a proof of principle we applied TACh to frozen mouse liver tissue. Combined with massive parallel sequencing TACh identifies accessible regions that are associated with euchromatic features and accessibility at transcriptional start sites correlates positively with levels of gene transcription. Accessible chromatin identified by TACh overlaps to a large extend with accessible chromatin identified by DNase I using nuclei purified from freshly isolated liver tissue as starting material. The similarities are most pronounced at highly accessible regions, whereas identification of less accessible regions tends to be more divergence between nucleases. Interestingly, we show that some of the differences between DNase I and Benzonase relate to their intrinsic sequence biases and accordingly accessibility of CpG islands is probed more efficiently using TACh.The TACh methodology identifies accessible chromatin derived from frozen tissue samples. We propose that this simple, robust approach can be applied across a broad range of clinically relevant samples to allow demarcation of regulatory elements of considerable prognostic significance.

Dataset Information

Trac-looping measures genome structure and chromatin accessibility.

Publications

Trac-looping measures genome structure and chromatin accessibility.

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