Project description:Dinoflagellate chromosomes represent a unique evolutionary experiment, as they exist in a permanently condensed, liquid crystalline state, are not packaged by histones, and contain genes organized into polycistronic arrays, with minimal transcriptional regulation. We analyze the 3D genome of {Breviolum minutum}, and find large topological domains without chromatin loops, demarcated by convergent gene array boundaries (``dinoTADs’’). Transcriptional inhibition degrades dinoTADs, implicating transcription-induced supercoiling as the primary topological force in dinoflagellates.
Project description:Liver cancer, particularly hepatocellular carcinoma (HCC), poses a significant global threat to human lives. To advance the development of innovative diagnostic and treatment approaches, it is essential to examine the hidden features of HCC, particularly its 3D genome architecture, which is not well understood. In this study, we investigated the 3D genome organization of four HCC cell lines—Hep3B, Huh1, Huh7, and SNU449—using in situ Hi-C and ATAC-seq. Our findings revealed that HCCs had elevated long-range interactions compared to HMECs, both intra- and interchromosomal. Unexpectedly, they displayed cell line-specific compartmental modifications at the Mb scale, which could aid in determining HCC subtypes. At the sub-Mb scale, we observed a decrease in intra-TAD interactions and chromatin loops in HCCs compared to HMECs. Lastly, we discovered a correlation between gene expression and 3D chromatin architecture in SLC8A1, which encodes the sodium-calcium antiporter known to induce apoptosis. Our findings suggest that HCCs have a distinct 3D genome organization that is different from normal and other cancer cells. Overall, we take this as evidence that genome organization plays a crucial role in cancer phenotype determination. Further exploration of epigenetics in HCC will lead us to a better understanding of specific gene regulation mechanisms and uncover novel targets for cancer treatments.
Project description:Liver cancer, particularly hepatocellular carcinoma (HCC), poses a significant global threat to human lives. To advance the development of innovative diagnostic and treatment approaches, it is essential to examine the hidden features of HCC, particularly its 3D genome architecture, which is not well understood. In this study, we investigated the 3D genome organization of four HCC cell lines—Hep3B, Huh1, Huh7, and SNU449—using in situ Hi-C and ATAC-seq. Our findings revealed that HCCs had elevated long-range interactions compared to HMECs, both intra- and interchromosomal. Unexpectedly, they displayed cell line-specific compartmental modifications at the Mb scale, which could aid in determining HCC subtypes. At the sub-Mb scale, we observed a decrease in intra-TAD interactions and chromatin loops in HCCs compared to HMECs. Lastly, we discovered a correlation between gene expression and 3D chromatin architecture in SLC8A1, which encodes the sodium-calcium antiporter known to induce apoptosis. Our findings suggest that HCCs have a distinct 3D genome organization that is different from normal and other cancer cells. Overall, we take this as evidence that genome organization plays a crucial role in cancer phenotype determination. Further exploration of epigenetics in HCC will lead us to a better understanding of specific gene regulation mechanisms and uncover novel targets for cancer treatments.
Project description:TADs, CTCF loop domains, and A/B compartments have been identified as important structural and functional components of 3D chromatin organization, yet the relationship between these features is not well understood. Using high-resolution Hi-C and HiChIP we show that Drosophila chromatin is organized into domains we term compartmental domains that correspond precisely with A/B compartments at high resolution. We find that transcriptional state is a major predictor of Hi-C contact maps in several eukaryotes tested, including C. elegans and A. thaliana. Architectural proteins insulate compartmental domains by reducing interaction frequencies between neighboring regions in Drosophila, but CTCF loops do not play a distinct role in this organism. In mammals, compartmental domains exist alongside CTCF loop domains to form topological domains. The results suggest that compartmental domains are responsible for domain structure in all eukaryotes, with CTCF playing an important role in domain formation in mammals.
Project description:The vascularization of engineered tissues and organoids has remained a major unresolved challenge in regenerative medicine. While multiple approaches have been developed to vascularize in vitro tissues, it has thus far not been possible to generate perfusable vessels in sufficiently close proximity and at sufficient small scale to perfuse large de novo tissues. Here, we achieve the perfusion of multi-mm3 tissue constructs by generating perfusable synthetic capillary-scale 3D channels. Our 3D soft microfluidic strategy is uniquely enabled by a 3D-printable 2-photon-polymerizable hydrogel formulation, which allows for precise microvessel printing at scales below the diffusion limit. We demonstrate that these large-scale engineered tissues are viable, proliferative and exhibit complex morphogenesis during long-term in-vitro culture, while avoiding hypoxia and necrosis. We show by scRNAseq and immunohistochemistry that neural differentiation is significantly accelerated in perfused neural constructs. Additionally, we illustrate the versatility of this platform by demonstrating long-term perfusion of developing liver tissue. This fully synthetic vascularization platform opens the door to the generation of human tissue models at unprecedented scale and complexity.
Project description:Chromosomes of metazoan organisms are partitioned in the interphase nucleus into discrete topologically associating domains (TADs). Borders between TADs are preferentially formed in regions containing high density of active genes and clusters of architectural protein binding sites. Transcription of most genes is turned off during the heat shock response in Drosophila. Here we show that temperature stress induces relocalization of architectural proteins from TAD borders to inside TADs, and this is accompanied by a dramatic rearrangement in the 3D organization of the nucleus. TAD border strength declines, allowing for an increase in long-distance inter-TAD interactions. Similar but quantitatively weaker effects are observed upon inhibition of transcription or depletion of individual architectural proteins. New heat shock-induced inter-TAD interactions result in increased contacts among enhancers and promoters of silenced genes, which recruit Pc and form Pc bodies at the nucleolus. These results suggest that the TAD organization of metazoan genomes is plastic and can be quickly reconfigured to allow new interactions between distant sequences. Analysis of 3D chromatin organization using Hi-C in Drosophila Kc167 cells. Cells were grown at 25 C and heat shocked for 20 min at 36.5 C. Cells were also treated with flavopiridol or triptolide to inhibit transcription elongation or initiation, respectively. Cells were depeleted of Cap-H2 or Rad21 using RNAi. Finally, cells depleted of RAd21 were subjected to heat shock at 36.5 C for 20 min.
Project description:Mapping the global proteome circuitry of the human cell is one of the central goals of the post-genomic era. Here, we combine high-throughput genome engineering of ~1,300 cell lines endogenously tagged with fluorescent protein fusions, 3D live-cell imaging, mass spectrometry (MS)-based high-speed interactomics and advanced machine learning to decode the interaction and localization architecture of the human proteome. We delineate interacting protein families and facilitate unbiased biological discovery by unsupervised clustering, while hierarchical analyses of the interactome superimposed to localization uncover principles that template cellular organization. Furthermore, we discover that localization patterns alone are often enough to predict molecular interactions. ‘OpenCell’ is a global proteome-scale resource for human protein localization and interaction at endogenous expression levels. Our analytical methods are open-source and our data set is presented as an advanced interactive website (‘OpenCell’.czbiohub.org) to empower the community with the quantitative cartography of human cellular organization at proteome level.