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Results for “3D chromosomal organization”

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At least 19 recordsLinked to original sources

PubMed2026

Metadomain and metaloop genome interactions in mammalian T cells.

Recent studies have advanced understanding of chromosomal organization and its role in gene regulation, yet most analyses focus on short-range interactions (<2 Mb), limiting insight into broader architecture. The relationships between topologically associating domains (TADs), sub-TAD loops, cross-TAD interactions, and chromosomal compartmentalization remain poorly understood. Here, using high-resolution Hi-C analysis, we identify extensive multi-megabase and interchromosomal interactions (metaloops) in T lymphocytes that organize into meta-TAD associations (metadomains). These metaloops connect distal promoters and regulatory elements of genes functionally important in T cells, including Ctla4, Ikzf2, Il2ra, Ets1, and Foxo1. Reanalysis of mouse and human datasets confirms their reproducibility and dependence on superenhancers. Genome-wide clustering reveals three distinct interchromosomal hubs, including a superenhancer-enriched hub linked to T cell-specific gene activation. Integrative analysis of regulatory genomics data identifies factors associated with short- versus long-range interactions. This study introduces a broadly applicable computational framework and reveals features of T cell genome organization.

Animals↗

PubMed2024

Principles of bacterial genome organization, a conformational point of view.

Bacterial chromosomes are large molecules that need to be highly compacted to fit inside the cells. Chromosome compaction must facilitate and maintain key biological processes such as gene expression and DNA transactions (replication, recombination, repair, and segregation). Chromosome and chromatin 3D-organization in bacteria has been a puzzle for decades. Chromosome conformation capture coupled to deep sequencing (Hi-C) in combination with other "omics" approaches has allowed dissection of the structural layers that shape bacterial chromosome organization, from DNA topology to global chromosome architecture. Here we review the latest findings using Hi-C and discuss the main features of bacterial genome folding.

Genome, Bacterial↗

PubMed2026

Condensin accelerates long-range intra-chromosomal interactions.

The 3D genome organization plays a key role in regulating interactions among chromosomal loci. While Chromosome Conformation Capture (3C)-based methods have provided static snapshots of chromatin architecture, the kinetics of chromosomal encounters in live cells remain poorly characterized. In this study, we employ Chemically Induced Chromosomal Interaction (CICI) to measure encounter times between multiple loci pairs in G1-arrested budding yeast. Our results show that chromosome motion closely follows the Rouse polymer model, with similar diffusion parameters at all tested loci. Surprisingly, we find that long-range intra-chromosomal encounters occur significantly faster than inter-chromosomal encounters at similar 3D distances. Using targeted depletion experiments, we identify condensin, but not cohesin, as the complex mostly responsible for these rapid intra-chromosomal interactions. This is further supported by Hi-C analysis, which reveals that condensin promotes long-distance intra-chromosomal interactions in G1 yeast. Through polymer simulations, we estimate that condensin extrudes chromatin at ~2 kb/s with a density of one complex per 1-2 Mb and a processivity of 120-220 kb. These findings uncover a novel role for condensin in shaping the interphase genome organization and provide new insights into chromosomal search dynamics in vivo.

Saccharomyces cerevisiae↗

PubMed2025

MaxComp: Predicting single-cell chromatin compartments from 3D chromosome structures.

The genome is organized into distinct chromatin compartments with at least two main classes, a transcriptionally active A and an inactive B compartment, broadly corresponding to euchromatin and heterochromatin. Chromatin regions within the same compartment preferentially interact with each other over regions in the opposite compartment. A/B compartments are traditionally identified from ensemble Hi-C contact frequency matrices using principal component analysis of their covariance matrices. However, defining compartments at the single-cell level from sparse single-cell Hi-C data is challenging, especially since homologous copies are often not resolved. To address this, we present MaxComp, an unsupervised method, for inferring single-cell A/B compartments based on 3D geometric considerations in single-cell chromosome structures-derived either from multiplexed FISH-omics imaging or 3D structure models derived from Hi-C data. By representing each 3D chromosome structure as an undirected graph with edge-weights encoding structural information, MaxComp reformulates compartment prediction as a variant of the Max-cut problem, solved using semidefinite graph programming (SPD) to optimally partition the graph into two structural compartments. Our results show that the population average of MaxComp single-cell compartment annotations closely matches those derived from ensemble Hi-C principal component analysis, demonstrating that compartmentalization can be recovered from geometric principles alone, using only the 3D coordinates and nuclear microenvironment of chromatin regions. Our approach reveals widespread cell-to-cell variability in compartment organization, with substantial heterogeneity across genomic loci. When applied to multiplexed FISH imaging data, MaxComp also uncovers relationships between compartment annotations and transcriptional activity at the single-cell level. In summary, MaxComp offers a new framework for understanding chromatin compartmentalization in single cells, connecting 3D genome architecture, and transcriptional activity with the cell-to-cell variations of chromatin compartments.

Chromatin↗

PubMed2025

Effects of Lamina-Chromatin Attachment on Super Long-Range Chromatin Interactions.

The interactions between chromatin and lamin proteins localized on the nuclear envelope play a crucial role in the three-dimensional (3D) organization of the genome. This study investigates the influence of lamin associated domains (LADs) on genome organization at the chromosome level using 3D polymer models of mouse embryonic fibroblasts (MEFs) and embryonic stem cells (mESCs). By integrating genome-wide LAD maps from DamID assays, we simulated chromatin conformations with and without LAD attachment to the nuclear envelope. Our results show that incorporating LAD-lamin interactions yields a radial chromatin distribution consistent with experimental observations. Moreover, LAD-lamin interactions induce significant super long-range chromatin contacts across distant genomic regions. These findings suggest two distinct mechanisms driving induction of chromatin interactions by LAD-lamin attachment.

3D single cell conformations↗

PubMed2026

Glucose-6-phosphate dehydrogenase variants modify 3D genomic organization to suppress maladaptive gene expression and vascular disease.

The 3D genome architecture is a higher-order organization of chromosomes within the nucleus that is critical to the control of epigenomic modifications. However, our knowledge regarding the role of 3D genomic organization in the regulation of vascular gene expression and function is lacking. In the present study, CRISPR-engineered rats modelled after two common polymorphisms (S188F and N126D) in human glucose-6-phosphate dehydrogenase (G6PD) revealed modifications to the 3D genome in aortas from rats expressing a deficient G6PD variant (S188F), but not a non-deficient one (N126D), is associated with: 1] up-regulated expression of TET enzymes that augmented expression of genes encoding antiproliferative proteins, 2] suppressed expression of genes encoding inflammatory/thrombotic/fibrotic proteins, and 3] reduced angiotensin II-induced aortic stiffness and hypertension. G6PD interacted with MATRIN-3, a nuclear matrix/scaffold protein, and a deficient G6PD variant increased the relative abundance of MATR3 and CCCTC-binding factors, potentially modifying 3D-genome structure. Additionally, G6PD deficiency-induced enrichment of H3K27ac likely influences the establishment and maintenance of the 3D genome. Therefore, we propose that the nexus between metabolism and the 3D genome regulates arterial gene expression and vascular disease.

Animals↗

PubMed2025

Generating three-dimensional genome structures with a variational quantum algorithm.

Chromosome conformation capture experiments have revealed the underlying spatial interactions that govern three-dimensional (3D) genome organization and topology. Detecting 3D contacts between genomic loci considerably enhances our understanding of fundamental regulatory processes. Modeling 3D structures from experimental contact matrices can further contextualize the relationship between 3D genome organization and regulation. While classical algorithms have been successful in reconstructing genomic conformations, we investigate the prospect of quantum computation to aid in modeling the conformational space. In this context, we propose a novel variational quantum algorithm (VQA) to model the distribution of 3D genomic structures from experimental contact data. Through rigorous evaluations, we demonstrate the capability of our algorithm to sample ensembles of viable 3D conformations that agree well with experimental and simulated contact data. Furthermore, we extend our methodology to model the conformational space of a single cell or a population of cells. In the advent of sufficient quantum utility, the insights gained from this study can serve as a foundation for investigating high-resolution, large-scale ensembles of genomic conformations through generative VQAs.

Algorithms↗

PubMed2025

Structural basis of differential gene expression at eQTLs loci from high-resolution ensemble models of 3D single-cell chromatin conformations.

MOTIVATION: Techniques such as high-throughput chromosome conformation capture (Hi-C) have provided a wealth of information on nucleus organization and genome important for understanding gene expression regulation. Genome-Wide Association Studies have identified numerous loci associated with complex traits. Expression quantitative trait loci (eQTL) studies have further linked the genetic variants to alteration in expression levels of associated target genes across individuals. However, the functional roles of many eQTLs in noncoding regions remain unclear. Current joint analyses of Hi-C and eQTLs data lack advanced computational tools, limiting what can be learned from these data. RESULTS: We developed a computational method for simultaneous analysis of Hi-C and eQTL data, capable of identifying a small set of nonrandom interactions from all Hi-C interactions. Using these nonrandom interactions, we reconstructed large ensembles (×105) of high-resolution single-cell 3D chromatin conformations with thorough sampling, accurately replicating Hi-C measurements. Our results revealed many-body interactions in chromatin conformation at the single-cell level within eQTL loci, providing a detailed view of how 3D chromatin structures form the physical foundation for gene regulation, including how genetic variants of eQTLs affect the expression of associated eGenes. Furthermore, our method can deconvolve chromatin heterogeneity and investigate the spatial associations of eQTLs and eGenes at subpopulation level, revealing their regulatory impacts on gene expression. Together, ensemble modeling of thoroughly sampled single-cell chromatin conformations combined with eQTL data, helps decipher how 3D chromatin structures provide the physical basis for gene regulation, expression control, and aid in understanding the overall structure-function relationships of genome organization. AVAILABILITY AND IMPLEMENTATION: It is available at https://github.com/uic-liang-lab/3DChromFolding-eQTL-Loci.

Quantitative Trait Loci↗

PubMed2025

3D STED Imaging of Isolated Arabidopsis thaliana Nuclei.

Microscopy imaging of chromatin offers valuable insights into its spatial organization in the nucleus, a novel epigenetic dimension influencing the genome's functions. Particularly, visualization at the nanoscale in single cells is uniquely complementary to molecular profiling methods averaging chromatin configuration and composition over thousands of cells. How are chromatin and chromosomal domains distributed in relation to gene expression? How variable are these configurations? How do chromatin domains evolve in structure, composition, and distribution during cellular differentiation or cellular responses to environmental stimuli? Super-resolution microscopy techniques, like stimulated emission depletion (STED), are key in answering such questions. However, such imaging techniques are not often used in the field of plant cell biology compared to mammalian counterparts, which has greatly advanced our understanding of the 3D principles in genome organization. In an effort to bridge this gap, we provide a clear guide for isolating, embedding, immunostaining, and STED imaging intact leaf nuclei from Arabidopsis thaliana in 3D.

Arabidopsis↗

PubMed2026

Folding a broken genome: the versatile roles of cohesin in genome maintenance.

Cohesin is a protein complex that shapes 3D genome organization through two distinct mechanisms. First, cohesin tethers replicated chromatids from DNA replication until mitosis. This process, known as sister chromatid cohesion, ensures accurate chromosome segregation and enables high-fidelity DNA repair through homologous recombination between the sister chromatids. Second, cohesin organizes the genome during interphase by dynamically extruding chromatin loops, structures that have key roles in gene regulation. Recent work has shown that, in addition to the well-established repair functions of sister chromatid cohesion, cohesin-mediated chromatin looping is closely linked to the repair of DNA double-strand breaks - one of the most toxic DNA lesions. In this Review, we discuss the central roles of cohesin in maintaining genome stability, with emphasis on the cellular response to DNA double-strand breaks. We review how dynamic loop structures facilitate signalling of repair events and promote long-range chromatin motions that underpin the repair process. Overall, its dual mode of action - cohesion and loop extrusion - positions cohesin as a central regulator of chromatin architecture and genome maintenance.

Cohesins↗

PubMed2023

Mega-Enhancer Bodies Organize Neuronal Long Genes in the Cerebellum.

Dynamic regulation of gene expression plays a key role in establishing the diverse neuronal cell types in the brain. Recent findings in genome biology suggest that three-dimensional (3D) genome organization has important, but mechanistically poorly understood functions in gene transcription. Beyond local genomic interactions between promoters and enhancers, we find that cerebellar granule neurons undergoing differentiation in vivo exhibit striking increases in long-distance genomic interactions between transcriptionally active genomic loci, which are separated by tens of megabases within a chromosome or located on different chromosomes. Among these interactions, we identify a nuclear subcompartment enriched for near-megabase long enhancers and their associated neuronal long genes encoding synaptic or signaling proteins. Neuronal long genes are differentially recruited to this enhancer-dense subcompartment to help shape the transcriptional identities of granule neuron subtypes in the cerebellum. SPRITE analyses of higher-order genomic interactions, together with IGM-based 3D genome modeling and imaging approaches, reveal that the enhancer-dense subcompartment forms prominent nuclear structures, which we term mega-enhancer bodies. These novel nuclear bodies reside in the nuclear periphery, away from other transcriptionally active structures, including nuclear speckles located in the nuclear interior. Together, our findings define additional layers of higher-order 3D genome organization closely linked to neuronal maturation and identity in the brain.

Journal Article↗

PubMed2025

Prediction and functional interpretation of inter-chromosomal genome architecture from DNA sequence with TwinC.

Three-dimensional nuclear DNA architecture comprises well-studied intra-chromosomal (cis) folding and less characterized inter-chromosomal (trans) interfaces. Current predictive models of 3D genome folding can effectively infer pairwise cis-chromatin interactions from the primary DNA sequence but generally ignore trans contacts. There is an unmet need for robust models of trans-genome organization that provide insights into their underlying principles and functional relevance. We present TwinC, an interpretable convolutional neural network model that reliably predicts trans contacts measurable through proximity ligation-dependent (in situ and intact Hi-C) and independent (DNA SPRITE) genome-wide chromatin conformation assays. . TwinC uses a paired sequence design from replicate Hi-C experiments to learn single base pair relevance in trans interactions across two stretches of DNA. The method achieves high predictive accuracy (AUROC=0.80) on a cross-chromosomal test set from in situ and intact Hi-C experiments in heart tissue. Furthermore, we train TwinC using in situ Hi-C data from the widely used GM12878 cell line and validate its performance with orthogonal DNA SPRITE assay in the same cell type. Mechanistically, the neural network learns the importance of compartments, chromatin accessibility, clustered transcription factor binding and G-quadruplexes in forming trans contacts. In summary, TwinC models and interprets trans genome architecture, shedding light on this poorly understood aspect of gene regulation.

Journal Article↗

PubMed2025

esBAF and INO80C fine-tune subcompartments and differentially regulate enhancer-promoter interactions.

The genome is compacted in the nucleus through a hierarchical chromatin organization, ranging from chromosome territories to compartments, topologically associating domains (TADs), and individual nucleosomes. Nucleosome remodeling complexes hydrolyze ATP to translocate DNA and thereby mobilize histone proteins. While nucleosome remodeling complexes have been extensively studied for their roles in regulating nucleosome positioning and accessibility, their contributions to higher-order chromatin architecture remain less well understood. Here, we investigate the roles of two key nucleosome remodelers, esBAF and INO80C, in shaping 3D genome organization in mouse embryonic stem cells. Using Hi-C, we find that loss of either remodeler has minimal effects on global compartment or TAD structures. In contrast, subcompartment organization is notably altered, suggesting that esBAF and INO80C contribute to finer-scale chromatin topology. To overcome the limited resolution of Hi-C for detecting regulatory loops, we employed promoter capture Micro-C (PCMC), which revealed that the loss of esBAF or INO80C alters a subset of promoter anchored looping interactions. Although these changes occur at distinct genomic loci for each remodeler, the affected sites are commonly enriched for bivalent chromatin regions bound by OCT4, SOX2, and NANOG (OSN), as well as BRG1 and INO80 themselves. Together, our findings reveal that esBAF and INO80C selectively influence subcompartment identity and enhancer-promoter communication at key regulatory loci, highlighting a previously underappreciated role for nucleosome remodelers in higher-order chromatin organization.

chromatin↗

PubMed2025

Genome reorganisation and expansion shape 3D genome architecture and define a distinct regulatory landscape in coleoid cephalopods.

How genomic changes translate into organismal novelties is often confounded by the multi-layered nature of genome architecture and the long evolutionary timescales over which molecular changes accumulate. Coleoid cephalopods (squid, cuttlefish, and octopus) provide a unique system to study these processes due to a large-scale chromosomal rearrangement in the coleoid ancestor that resulted in highly modified karyotypes, followed by lineage-specific fusions, translocations, and repeat expansions. How these events have shaped gene regulatory patterns underlying the evolution of coleoid innovations, including their large and elaborately structured nervous systems, novel organs, and complex behaviours, remains poorly understood. To address this, we integrate Micro-C, RNA-seq, and ATAC-seq across multiple coleoid species, developmental stages, and tissues. We find that while topological compartments are broadly conserved, hundreds of chromatin loops are species- and context-specific, with distinct regulation signatures and dynamic expression profiles. CRISPR-Cas9 knockout of a putative regulatory sequence within a conserved region demonstrates the role of loops in neural development and the prevalence of long-range, inter-compartmental interactions. We propose that differential evolutionary constraints across the coleoid 3D genome allow macroevolutionary processes to shape genome topology in distinct ways, facilitating the emergence of novel regulatory entanglements and ultimately contributing to the evolution and maintenance of complex traits in coleoids.

Journal Article↗

PubMed2026

One chromatin, many structures: From ensemble contact maps to single-cell 3D organization.

Understanding how chromatin folds in three dimensions remains challenging because most experimental assays capture low-dimensional projections of an underlying, highly heterogeneous polymer. Here, we present an ensemble-based interpretive framework built on the previously introduced Self-Returning Excluded Volume (SR-EV) model, a minimal generator of chromatin conformations using a nucleosome-indexed coarse-grained representation based on stochastic return rules and excluded-volume geometry. Despite its simplicity, SR-EV recapitulates key experimental signatures across scales: heterogeneous nanoscale packing domains resembling ChromEMT and ChromSTEM observations, sparse and highly variable single-configuration contact patterns analogous to single-cell chromosome conformation capture (Hi-C), and robust ensemble-level contact enrichment consistent with topologically associating domains (TADs). In this framework, Hi-C loop and TAD signatures are interpreted as ensemble-level statistical enrichments rather than invariant features of single-cell conformations. SR-EV is explicitly designed to generate large ensembles of complete three-dimensional chromatin configurations that can be projected consistently onto two-dimensional contact maps and one-dimensional genomic profiles. By introducing architectural-protein effects only through ensemble selection rather than explicit forces, SR-EV supports a separation between intrinsic polymer geometry and regulatory bias and suggests that TAD-like features can emerge as statistical enrichments rather than deterministic three-dimensional structures. Coordination number and probe-based accessibility computed directly from SR-EV provide a unified link between three-dimensional packing, two-dimensional contact maps, and one-dimensional genomic profiles. The main contribution of this work is to show, within a single coarse-grained framework, how these multimodal observables arise as linked projections of the same heterogeneous chromatin ensemble through averaging and conditional sampling. Together, these results establish SR-EV as a minimal and geometrically grounded mesoscale reference framework for interpreting how heterogeneous chromatin ensembles give rise to multimodal experimental observables while remaining consistent with the fact that chromatin organization is realized in individual cells.

Chromatin↗

PubMed2026

Hi-C calibration by chemically induced chromosomal interactions.

The genome-wide chromosome conformation capture method, Hi-C, has greatly advanced our understanding of genome organization. However, its quantitative properties, including sensitivity, bias, and linearity, remain challenging to assess. Measuring these properties in vivo is difficult due to the heterogenous and dynamic nature of chromosomal interactions. Here, using Chemically Induced Chromosomal Interaction (CICI) method, we create stable intra- and inter-chromosomal interactions in G1-phase budding yeast across a broad range of contact frequencies. Hi-C analysis of these engineered cell populations demonstrates that static intra-chromosomal loops do not generate Topologically Associated Domains (TADs) and only promote 3D proximity within 10-60 kb flanking regions. At moderate sequencing depth, Hi-C is sensitive enough to detect interactions occurring in 5-10% of cells. It also shows no inherent bias toward intra- versus inter-chromosomal interactions. Furthermore, we observe a linear relationship between Hi-C signal intensity and contact frequency. These findings illuminate the intrinsic properties of the Hi-C assay and provide a robust framework for its calibration.

Chromosomes, Fungal↗

PubMed2026

Modeling meningioma in vitro in the omics era.

Meningioma biology has been substantially clarified by recent omics-based studies, which have identified recurrent mutations, copy-number alterations, and distinct molecular subgroups. However, although these approaches have provided a valuable framework, they are inherently limited in their ability to establish direct causal relationships. The mechanistic studies are therefore indispensable for translating these molecular observations into biological understanding. Nevertheless, the mechanistic literature has often evolved in a fragmented manner, with individual pathways and model systems studied in relative isolation from the broader multi-omic landscape. In this review, we synthesize these complementary bodies of work into an integrated framework and outline a clear roadmap for future studies. We first review the historical development of established meningioma cell lines, their current molecular characterization, and the recent emergence of 3D models and organoids. Intrinsic challenges in modeling meningioma in vitro are discussed, including the difficulty of establishing immortalized cell lines from predominantly benign tumors, genetic alterations introduced during immortalization, and drift under culture conditions that differ substantially from those of the parental tumors. Next, insights from functional studies centered on these models are integrated within the molecular framework established by large-scale omics analyses. To avoid fragmentation and overemphasis on isolated findings, prior studies are organized into six categories based on major signaling pathways: Hippo, PI3K/Akt/mTOR, MAPK, Wnt/β-catenin, FOXM1, and Notch. Finally, lessons from other cancer models, including experimental approaches to chromosome-scale genomic disturbances, are considered to provide a more integrated view of meningioma biology and to highlight directions for future research.

Meningioma↗

PubMed2025

The Use of APC/C Antagonists to Promote Mitotic Catastrophe in Cancer Cells.

The multiprotein subunit E3 ubiquitin ligase Anaphase-Promoting Complex/Cyclosome (APC/C) plays a key role in the control of mitosis progression. APC/C is the ultimate effector of the Spindle Assembly Checkpoint (SAC), the signaling system of higher organisms including the human that monitors the proper attachment of chromosomes to microtubules during cell division. Defects in this process result in genome instability, aneuploidy, premature aging, and cancer. APC/C roles in the SAC require its activation by the protein Cdc20. Interfering with APC/C activation by Cdc20 impairs APC/C substrate recognition, resulting in a delayed mitotic exit and eventually inducing cell death. This may be advantageous for the treatment of cancer and malignancies associated with SAC dysregulation. Here we describe a protocol to interfere with mitotic exit through the use of commercially available (Apcin, proTAME) as well as innovative small molecules we have developed that function as antagonists of APC/C activation by Cdc20. We show that the use of these molecules alone and in combination is effective to promote mitotic catastrophe and suppress cell expansion in 2D and 3D (spheroids) cancer cells of different tissue origin, including breast, cervical, and ovarian cancer.

Humans↗