Project description:Chromosome conformation capture (3C)-based assays are used to map chromatin interactions genome-wide. Quantitative analyses of chromatin interaction maps can lead to insights into the spatial organization of chromosomes and the mechanisms by which they fold. A number of protocols such as in situ Hi-C and Micro-C are now widely used and these differ in key experimental parameters including cross-linking chemistry and chromatin fragmentation strategy. To understand how the choice of experimental protocol determines the ability to detect and quantify aspects of chromosome folding we have performed a systematic evaluation of experimental parameters of 3C-based protocols. We find that different protocols capture different 3D genome features with different efficiencies. First, the use of crosslinkers such as DSG in addition to formaldehyde improves signal-to-noise allowing detection of thousands of additional loops and strengthening compartment signal. Second, fragmenting chromatin to the level of nucleosomes using MNase allows detection of more loops. On the other hand, protocols that generate larger multi-kb fragments produce stronger compartmentalization signals. We confirmed our results in multiple cell states such as pluripotent and differentiated cells as well as cell cycle stages; Mitosis and G1. Based on these insights we developed Hi-C 3.0, a single protocol that can be used to both efficiently detect chromatin loops and to quantify compartmentalization. Finally, this study produced ultra-deeply sequenced reference interaction maps using in situ Hi-C, Micro-C and Hi-C 3.0 for commonly cell lines in the 4D Nucleome Project.
Project description:Chromosome conformation capture (3C)-based assays are used to map chromatin interactions genome-wide. Quantitative analyses of chromatin interaction maps can lead to insights into the spatial organization of chromosomes and the mechanisms by which they fold. A number of protocols such as in situ Hi-C and Micro-C are now widely used and these differ in key experimental parameters including cross-linking chemistry and chromatin fragmentation strategy. To understand how the choice of experimental protocol determines the ability to detect and quantify aspects of chromosome folding we have performed a systematic evaluation of experimental parameters of 3C-based protocols. We find that different protocols capture different 3D genome features with different efficiencies. First, the use of crosslinkers such as DSG in addition to formaldehyde improves signal-to-noise allowing detection of thousands of additional loops and strengthening compartment signal. Second, fragmenting chromatin to the level of nucleosomes using MNase allows detection of more loops. On the other hand, protocols that generate larger multi-kb fragments produce stronger compartmentalization signals. We confirmed our results in multiple cell states such as pluripotent and differentiated cells as well as cell cycle stages; Mitosis and G1. Based on these insights we developed Hi-C 3.0, a single protocol that can be used to both efficiently detect chromatin loops and to quantify compartmentalization. Finally, this study produced ultra-deeply sequenced reference interaction maps using in situ Hi-C, Micro-C and Hi-C 3.0 for commonly cell lines in the 4D Nucleome Project.
Project description:Chromosome conformation capture (3C)-based assays are used to map chromatin interactions genome-wide. Quantitative analyses of chromatin interaction maps can lead to insights into the spatial organization of chromosomes and the mechanisms by which they fold. A number of protocols such as in situ Hi-C and Micro-C are now widely used and these differ in key experimental parameters including cross-linking chemistry and chromatin fragmentation strategy. To understand how the choice of experimental protocol determines the ability to detect and quantify aspects of chromosome folding we have performed a systematic evaluation of experimental parameters of 3C-based protocols. We find that different protocols capture different 3D genome features with different efficiencies. First, the use of crosslinkers such as DSG in addition to formaldehyde improves signal-to-noise allowing detection of thousands of additional loops and strengthening compartment signal. Second, fragmenting chromatin to the level of nucleosomes using MNase allows detection of more loops. On the other hand, protocols that generate larger multi-kb fragments produce stronger compartmentalization signals. We confirmed our results in multiple cell states such as pluripotent and differentiated cells as well as cell cycle stages; Mitosis and G1. Based on these insights we developed Hi-C 3.0, a single protocol that can be used to both efficiently detect chromatin loops and to quantify compartmentalization. Finally, this study produced ultra-deeply sequenced reference interaction maps using in situ Hi-C, Micro-C and Hi-C 3.0 for commonly cell lines in the 4D Nucleome Project.
Project description:Background: Identification of locus-locus contacts at the chromatin level provides a valuable foundation for understanding of nuclear architecture and function and a valuable tool for inferring long-range linkage relationships. As one approach to this, chromatin conformation capture-based techniques allow creation of genome spatial organization maps. While such approaches have been available for some time, methodological advances will be of considerable use in minimizing both time and input material required for successful application. Results: Here we report a modified tethered conformation capture protocol that utilizes a series of rapid and efficient molecular manipulations. We applied the method to Caenorhabditis elegans, obtaining chromatin interaction maps that provide a sequence-anchored delineation of salient aspects of Caenorhabditis elegans chromosome structure, demonstrating a high level of consistency in overall chromosome organization between biological samples collected under different conditions. In addition to the application of the method to defining nuclear architecture, we found the resulting chromatin interaction maps to be of sufficient resolution and sensitivity to enable detection of large-scale structural variants such as inversions or translocations. Conclusion: Our streamlined protocol provides an accelerated, robust, and broadly applicable means of generating chromatin spatial organization maps and detecting genome rearrangements without a need for cellular or chromatin fractionation. Application of modified version of TCC protocl using different C. elegans strains (N2 and glp-1) in L1, and adult life stages.
Project description:The spatial organization of genes in the interphase nucleus plays an important role in establishment and regulation of gene expression. Contradicting results have been reported to date, with little consensus about the dynamics of nuclear organization and the features of the contact loci. In this study we investigated the properties and dynamics of genomic loci that are in contact with glucocorticoid receptor (GR)-responsive loci. We took a systematic approach, combining genome-wide interaction profiling by the chromosome conformation capture-on-chip (4C) technology with expression, protein occupancy, and chromatin accessibility profiles. This approach allowed a comprehensive analysis of how distinct features of the linear genome are organized in the three-dimensional nuclear space in the context of rapid gene regulation. We found that the transcriptional response to GR occurs without dramatic nuclear reorganization. Moreover, contrary to the view of transcription-driven organization, even genes with opposite transcriptional responses co-localize. Regions contacting GR-regulated genes are not particularly enriched for GR-regulated loci or for any functional group of genes, suggesting that these subnuclear environments are not organized to respond to a specific factor. The contact regions are, however, highly enriched for DNaseI hypersensitive sites which represent the entire cell type-specific regulatory sites. These findings indicate that the nucleus is pre-organized in a conformation allowing rapid transcriptional reprogramming, and suggest that a major force in shaping genome architecture is the repertoire of chromatin binding factors. Numerous open chromatin loci may be arranged in nuclear domains that are poised to respond to diverse signals in general, and to permit efficient gene regulation. Fourteen arrays total: Eight microarrays from individual biological replicates, and six microarrays each from a pool of two biological replicates. This submission represents the chromosome conformation capture-on-chip component of the study. The expression data are included in GSE26189.