Finding the 3D Structure of DNA for Stem Cell and Cancer Research Progress

Weill Cornell Medicine and New York Genome Center researchers, in collaboration with Oxford Nanopore Technologies, have developed a new method to assess on a large scale the three-dimensional structure of the human genome, or how the genome folds. The genome is the complete set of genetic instructions, DNA or RNA, enabling an organism to function.

Using this method, the researchers demonstrated that cell function, including gene expression, may be affected by groups of simultaneously interacting regulatory elements in the genome rather than pairs of these components.

They used genome-scale nanopore sequencing.

Future experiments will explore which specific groupings of genomic components are essential for various aspects of cell identity. The new technology may also help researchers to understand how stem cells, the immature, master cells of the body, differentiate into different cell types.

Researchers may be better able understand abnormalities in cancer cells.

Nature Biotechnology – high-order 3D chromatin conformations from genome-scale nanopore concatemer sequencing

High-order three-dimensional (3D) interactions between more than two genomic loci are common in human chromatin, but their role in gene regulation is unclear. Previous high-order 3D chromatin assays either measure distant interactions across the genome or proximal interactions at selected targets. To address this gap, we developed Pore-C, which combines chromatin conformation capture with nanopore sequencing of concatemers to profile proximal high-order chromatin contacts at the genome scale. We also developed the statistical method Chromunity to identify sets of genomic loci with frequencies of high-order contacts significantly higher than background (‘synergies’). Applying these methods to human cell lines, we found that synergies were enriched in enhancers and promoters in active chromatin and in highly transcribed and lineage-defining genes. In prostate cancer cells, these included binding sites of androgen-driven transcription factors and the promoters of androgen-regulated genes. Concatemers of high-order contacts in highly expressed genes were demethylated relative to pairwise contacts at the same loci. Synergies in breast cancer cells were associated with tyfonas, a class of complex DNA amplicons. These results rigorously link genome-wide high-order 3D interactions to lineage-defining transcriptional programs and establish Pore-C and Chromunity as scalable approaches to assess high-order genome structure.

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