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At least 19 recordsLinked to original sources

PubMed2026

Exhausted CD8+ T cell fate is programmed by dynamic CTCF-mediated enhancer activation and invariant CTCF-imposed barriers.

Exhausted CD8+ T (TEX) cells undergo extensive genome reorganization during differentiation, yet the drivers of this process remain elusive. Here we show that CTCF programmed CD8+ TEX cell fates through two distinct modes of action. CTCF acquired de novo binding sites and concordantly induced open chromatin in early CD8+ TEX cells responding to chronic viral infection. The dynamic CTCF binding activated enhancers and promoted chromatin looping. Consequently, genetic ablation of CTCF diminished chromatin accessibility and interaction strength, impairing CD8+ TEX cell proliferation, effector function and bioenergetic mobilization. Conversely, invariant CTCF binding acted as essential chromatin barriers, and loss of CTCF disrupted insulation and caused aberrant chromatin self-association and undue RNA polymerase II pausing, leading to excessive activation of exhaustion- and stemness-linked genes. Thus, CTCF balanced CD8+ TEX cell differentiation by gaining dynamic binding to induce cytotoxicity and sustain metabolic fitness, while its invariant binding compartmentalized exhaustion and stemness program genes to prevent their overexuberant activation.

CCCTC-Binding Factor↗

PubMed2026

Histone H3K27ac spreads from enriched chromatin domains into neighboring regions upon loss of CTCF binding.

Acetylation of histone H3 at lysine 27 (H3K27ac) is enriched at enhancers and highly transcribed genes. Our previous study showed that an H3K27ac-enriched chromatin domain expanded into neighboring regions following the deletion of CTCF-binding motifs flanking the domain. In this study, we explored the spreading of H3K27ac on a genome-wide scale by analyzing its distribution around CTCF-binding sites in human K562 cells and examining changes upon CTCF loss. We found that a subset of CTCF-binding sites demarcates H3K27ac-enriched domains. Upon loss of CTCF binding, H3K27ac levels increased in most regions adjacent to these domains, indicating that H3K27ac can spread into neighboring chromatin. This spreading was accompanied by elevated transcription of nearby genes. Chromatin features, including histone modifications, CTCF-binding intensity, and CTCF-mediated chromatin interactions, were associated with the H3K27ac spreading. Notably, enhancers were more enriched within domains that exhibited H3K27ac spreading compared to those that did not, and the deletion of enhancers from the CTCF motif-deficient β-globin locus attenuated the spreading. These findings indicate that CTCF-binding sites serve as boundaries for H3K27ac-enriched domains and that, in the absence of CTCF binding, H3K27ac can spread into neighboring regions. H3K27ac spreading appears to be influenced by multiple chromatin features and to contribute to the transcriptional increase of nearby genes.

CTCF↗

PubMed2025

Interpreting the CTCF-mediated sequence grammar of genome folding with AkitaV2.

Interphase mammalian genomes are folded in 3D with complex locus-specific patterns that impact gene regulation. CTCF (CCCTC-binding factor) is a key architectural protein that binds specific DNA sites, halts cohesin-mediated loop extrusion, and enables long-range chromatin interactions. There are hundreds of thousands of annotated CTCF-binding sites in mammalian genomes; disruptions of some result in distinct phenotypes, while others have no visible effect. Despite their importance, the determinants of which CTCF sites are necessary for genome folding and gene regulation remain unclear. Here, we update and utilize Akita, a convolutional neural network model, to extract the sequence preferences and grammar of CTCF contributing to genome folding. Our analyses of individual CTCF sites reveal four predictions: (i) only a small fraction of genomic sites are impactful; (ii) impact is highly dependent on sequences flanking the core CTCF binding motif; (iii) core and flanking nucleotides contribute largely additively to the overall impact of a site; (iv) sites created as combinations of different core and flanking sequences have impacts proportional to the product of their average impacts, i.e. they are broadly compatible. Our analysis of collections of CTCF sites make two predictions for multi-motif grammar: (i) insulation strength depends on the number of CTCF sites within a cluster, and (ii) pattern formation is governed by the orientation and spacing of these sites, rather than any inherent specialization of the CTCF motifs themselves. In sum, we present a framework for using neural network models to probe the sequences instructing genome folding and provide a number of predictions to guide future experimental inquiries.

CCCTC-Binding Factor↗

PubMed2025

Role of the CTCF binding site in Human T-Cell Leukemia Virus-1 pathogenesis.

During HTLV-1 infection, the virus integrates into the host cell genome as a provirus with a single CCCTC binding protein (CTCF) binding site (vCTCF-BS), which acts as an insulator between transcriptionally active and inactive regions. Previous studies have shown that the vCTCF-BS is important for maintenance of chromatin structure, regulation of viral expression, and DNA and histone methylation. Here, we show that the vCTCF-BS also regulates viral infection and pathogenesis in vivo in a humanized (Hu) mouse model of adult T-cell leukemia/lymphoma. Three cell lines were used to initiate infection of the Hu-mice, i) HTLV-1-WT which carries an intact HTLV-1 provirus genome, ii) HTLV-1-CTCF, which contains a provirus with a mutated vCTCF-BS which abolishes CTCF binding, and a stop codon immediately upstream of the mutated vCTCF-BS which deletes the last 23 amino acids of the p12 gene, and iii) HTLV-1-p12stop that contains the intact vCTCF-BS, but retains the same stop codon in p12 as in the HTLV-1-CTCF cell line. Hu-mice were infected with mitomycin-treated or irradiated HTLV-1 producing cell lines. There was a delay in pathogenicity when Hu-mice were infected with the HTLV-1-CTCF virus compared to mice infected with either HTLV-1-p12 stop or HTLV-1-WT virus. Proviral load (PVL), spleen weights, and CD4 T cell counts were significantly lower in HTLV-1-CTCF infected mice compared to HTLV-1-p12stop infected mice. Furthermore, we found a direct correlation between the PVL in peripheral blood and death of HTLV-1-CTCF infected mice. In cell lines, we found that the vCTCF-BS regulates Tax expression in a time-dependent manner. The scRNAseq analysis of splenocytes from infected mice suggests that the vCTCF-BS plays an important role in activation and expansion of T lymphocytes in vivo. Overall, these findings indicate that the vCTCF-BS regulates Tax expression, proviral load, and HTLV pathogenicity in vivo.

Human T-lymphotropic virus 1↗

PubMed2026

cPRC1.2 and CTCF-mediated transition from poised to active chromatin loops at bivalent genes.

Polycomb Repressive Complex 1 (PRC1) and CCCTC-binding factor (CTCF) are critical regulators of 3D chromatin architecture that influence cellular transcriptional programs. Although the role of CTCF in chromatin organization is well-known, the involvement of PRC1 is less understood. In this study, we identify an unexpected role for the canonical Pcgf2-containing PRC1 complex (cPRC1.2) in activating bivalent genes. Hi-C revealed that cPRC1.2 forms chromatin loops at bivalent promoters, rendering them poised for activation. Pcgf2 deletion disrupts cPRC1.2 loops and impairs the transcriptional induction of crucial target genes necessary for neuronal differentiation. Furthermore, we identify CTCF enrichment at cPRC1.2 loop anchors and at Polycomb group (PcG) bodies, suggesting that PRC1 and CTCF cooperatively regulate chromatin loops. Through virtual 4C and other genomic analyses, we discover that establishing neuronal progenitor cell (NPC) identity involves a switch from cPRC1.2-mediated chromatin loops to CTCF-mediated active loops. Our results suggest a novel mechanism by which pre-formed PRC1 loops at lineage-specific genes maintain a poised state for subsequent CTCF-mediated active loops and gene activation in cell fate transitions.

CCCTC-Binding Factor↗

PubMed2024

PRC1 and CTCF-Mediated Transition from Poised to Active Chromatin Loops Drives Bivalent Gene Activation.

Polycomb Repressive Complex 1 (PRC1) and CCCTC-binding factor (CTCF) are critical regulators of 3D chromatin architecture that influence cellular transcriptional programs. Spatial chromatin structures comprise conserved compartments, topologically associating domains (TADs), and dynamic, cell-type-specific chromatin loops. Although the role of CTCF in chromatin organization is well-known, the involvement of PRC1 is less understood. In this study, we identified an unexpected, essential role for the canonical Pcgf2-containing PRC1 complex (cPRC1.2), a known transcriptional repressor, in activating bivalent genes during differentiation. Our Hi-C analysis revealed that cPRC1.2 forms chromatin loops at bivalent promoters, rendering them silent yet poised for activation. Using mouse embryonic stem cells (ESCs) with CRISPR/Cas9-mediated gene editing, we found that the loss of Pcgf2, though not affecting the global level of H2AK119ub1, disrupts these cPRC1.2 loops in ESCs and impairs the transcriptional induction of crucial target genes necessary for neuronal differentiation. Furthermore, we identified CTCF enrichment at cPRC1.2 loop anchors and at Polycomb group (PcG) bodies, nuclear foci with concentrated PRC1 and its tethered chromatin domains, suggesting that PRC1 and CTCF cooperatively shape chromatin loop structures. Through virtual 4C and other genomic analyses, we discovered that establishing neuronal progenitor cell (NPC) identity involves a switch from cPRC1.2-mediated chromatin loops to CTCF-mediated active loops, enabling the expression of critical lineage-specific factors. This study uncovers a novel mechanism by which pre-formed PRC1 and CTCF loops at lineage-specific genes maintain a poised state for subsequent gene activation, advancing our understanding of the role of chromatin architecture in controlling cell fate transitions.

Journal Article↗

PubMed2021

The Murine MHC Class II Super Enhancer IA/IE-SE Contains a Functionally Redundant CTCF-Binding Component and a Novel Element Critical for Maximal Expression.

In both humans and mice, CTCF-binding elements form a series of interacting loops across the MHC class II (MHC-II) locus, and CTCF is required for maximal MHC-II gene expression. In humans, a CTCF-bound chromatin insulator termed XL9 and a super enhancer (SE) DR/DQ-SE situated in the intergenic region between HLA-DRB1 and HLA-DQA1 play critical roles in regulating MHC-II expression. In this study, we identify a similar SE, termed IA/IE-SE, located between H2-Eb1 and H2-Aa of the mouse that contains a CTCF site (C15) and a novel region of high histone H3K27 acetylation. A genetic knockout of C15 was created and its role on MHC-II expression tested on immune cells. We found that C15 deletion did not alter MHC-II expression in B cells, macrophages, and macrophages treated with IFN-γ because of functional redundancy of the remaining MHC-II CTCF sites. Surprisingly, embryonic fibroblasts derived from C15-deleted mice failed to induce MHC-II gene expression in response to IFN-γ, suggesting that at least in this developmental lineage, C15 was required. Examination of the three-dimensional interactions with C15 and the H2-Eb1 and H2-Aa promoters identified interactions within the novel region of high histone acetylation within the IA/IE-SE (termed N1) that contains a PU.1 binding site. CRISPR/Cas9 deletion of N1 altered chromatin interactions across the locus and resulted in reduced MHC-II expression. Together, these data demonstrate the functional redundancy of the MHC-II CTCF elements and identify a functionally conserved SE that is critical for maximal expression of MHC-II genes.

Animals↗

PubMed2026

CTCF aligns single-cell TAD-like domain boundaries and stabilizes long-range active chromatin clusters.

CCCTC-binding factor (CTCF) is a key architectural protein in the three-dimensional (3D) genome, yet how its loss reshapes chromatin structure and transcription at single-cell resolution remains unclear. Using HiRES, which jointly profiles chromatin contacts and RNA from the same nucleus, we examined genome-wide effects of CTCF depletion. Topologically associating domain (TAD)-like domains (TLDs) across single cells remained largely unchanged in number and size after CTCF loss, but their boundaries became more variably positioned, and pseudobulk analyses revealed reduced interactions within A compartments. We also developed SALTAFinder to identify Spatially Aggregated Long-distance TLD Assemblies (SALTAs), clusters of TLDs occupying shared 3D space within single cells. A subset of SALTAs is enriched for highly expressed genes and super-enhancers and declines upon CTCF depletion. This structural reorganization coincided with a global reduction in per-cell RNA output, as indicated by HiRES and orthogonal measurements. Together, these findings suggest that CTCF contributes to the coordinated regulation of chromatin organization and transcriptional capacity and is associated with stabilization of long-range active chromatin clusters.

CCCTC-Binding Factor↗

PubMed2026

Disruption of CTCF binding by germline non-coding variants in CDKN2B suppress CDKN2A expression and predispose to melanoma.

Some melanoma-prone families linked to the 9p21 locus, harboring the established susceptibility gene CDKN2A, lack pathogenic protein-coding variants. Using whole-exome and targeted sequencing, we identified three rare single-nucleotide variants in two melanoma-prone families and one sporadic melanoma case. Variants map to a conserved CTCF-bound region within the first intron of CDKN2B that physically interacts with CDKN2A. Analysis of UK Biobank showed significant enrichment of variants in this region in melanoma cases. Variants result in diminished CTCF binding in vitro. CTCF ChIP-seq in fibroblasts from the carriers of the largest family demonstrated loss of CTCF binding, accompanied by weakened promoter interactions and allele-specific reduction of CDKN2A p16 transcript expression from the variant haplotype. CRISPR-based perturbation of this region and editing of the large family variant into melanocytes resulted in reduced expression of p14 and p16 CDKN2A transcripts. These findings suggest that non-coding regulatory variants function as high-penetrance susceptibility alleles in melanoma families by altering CDKN2A function.

Journal Article↗

PubMed2016

17q21 asthma-risk variants switch CTCF binding and regulate IL-2 production by T cells.

Asthma and autoimmune disease susceptibility has been strongly linked to genetic variants in the 17q21 haploblock that alter the expression of ORMDL3; however, the molecular mechanisms by which these variants perturb gene expression and the cell types in which this effect is most prominent are unclear. We found several 17q21 variants overlapped enhancers present mainly in primary immune cell types. CD4+ T cells showed the greatest increase (threefold) in ORMDL3 expression in individuals carrying the asthma-risk alleles, where ORMDL3 negatively regulated interleukin-2 production. The asthma-risk variants rs4065275 and rs12936231 switched CTCF-binding sites in the 17q21 locus, and 4C-Seq assays showed that several distal cis-regulatory elements upstream of the disrupted ZPBP2 CTCF-binding site interacted with the ORMDL3 promoter region in CD4+ T cells exclusively from subjects carrying asthma-risk alleles. Overall, our results suggested that T cells are one of the most prominent cell types affected by 17q21 variants.

Asthma↗

PubMed2025

Repression of CADM1 transcription by HPV type 18 is mediated by three-dimensional rearrangement of promoter-enhancer interactions.

Upon infection, human papillomavirus (HPV) manipulates host cell gene expression to create an environment that is supportive of a productive and persistent infection. The virus-induced changes to the host cell's transcriptome are thought to contribute to carcinogenesis. Here, we show by RNA-sequencing that oncogenic HPV18 episome replication in primary human foreskin keratinocytes (HFKs) drives host transcriptional changes that are consistent between multiple HFK donors. We have previously shown that HPV18 recruits the host protein CTCF to viral episomes to control the differentiation-dependent viral transcriptional programme. Since CTCF is an important regulator of host cell transcription via coordination of epigenetic boundaries and long-range chromosomal interactions, we hypothesised that HPV18 may also manipulate CTCF to contribute to host transcription reprogramming. Analysis of CTCF binding in the host cell genome by ChIP-Seq revealed that while the total number of CTCF binding sites is not altered by the virus, there are a sub-set of CTCF binding sites that are either enriched or depleted of CTCF. Many of these altered sites are clustered within regulatory elements of differentially expressed genes, including the tumour suppressor gene cell adhesion molecule 1 (CADM1), which supresses epithelial cell growth and invasion. We show that HPV18 establishment results in reduced CTCF binding at the CADM1 promoter and upstream enhancer. Loss of CTCF binding is coincident with epigenetic repression of CADM1, in the absence of CpG hypermethylation, while adjacent genes including the transcriptional regulator ZBTB16 are activated. These data indicate that the CADM1 locus is subject to topological rearrangement following HPV18 establishment. We tested this hypothesis using 4C-Seq (circular chromosome confirmation capture-sequencing) and show that HPV18 establishment causes a loss of long-range chromosomal interactions between the CADM1 transcriptional start site and the upstream transcriptional enhancer. These data show that HPV18 manipulates host cell promoter-enhancer interactions to drive transcriptional reprogramming that may contribute to HPV-induced disease progression.

Humans↗

PubMed2025

Defining three dimensional chromatin structures of pediatric and adolescent B cells using primary B cell and EBV-immortalized B cell reference genomes.

BACKGROUND/PURPOSE: Knowledge of the 3D genome is essential to elucidate genetic mechanisms driving autoimmune diseases. The 3D genome is distinct for each cell type, and it is uncertain whether cell lines faithfully recapitulate the 3D architecture of primary human cells or whether developmental aspects of the pediatric immune system require use of pediatric samples. We undertook a systematic analysis of B cells and B cell lines to compare 3D genomic features encompassing risk loci for juvenile idiopathic arthritis (JIA), systemic lupus (SLE), and type 1 diabetes (T1D). METHODS: We isolated B cells from four healthy individuals, ages 9-17. HiChIP was performed using a CTCF antibody, and CTCF peaks were called within each sample separately. Peaks observed in all four samples were identified. CTCF loops were called within the pediatric samples using three CTCF peak datasets: 1) self-called CTCF consensus peaks called within the pediatric samples, 2) ENCODE's publicly available GM12878 CTCF ChIP-seq peaks, and 3) ENCODE's primary B cell CTCF ChIP-seq peaks from two adult females. Differential looping was assessed within the pediatric samples and each of the three peak datasets. RESULTS: The number of consensus peaks called in the pediatric samples was similar to that identified in ENCODE's GM12878 and primary B cell datasets. We observed < 1% of loops that demonstrated significantly differential looping between peaks called within the pediatric samples themselves and when called using ENCODE GM12878 peaks. Significant looping differences were even fewer when comparing loops of the pediatric called peaks to those of the ENCODE primary B cell peaks. When querying loops found in juvenile idiopathic arthritis, type 1 diabetes, or systemic lupus erythematosus risk haplotypes, we observed significant differences in only 2.2%, 1.0%, and 1.3% loops, respectively, when comparing peaks called within the pediatric samples and ENCODE GM12878 dataset. The differences were even less apparent when comparing loops called with the pediatric vs ENCODE adult primary B cell peak datasets. CONCLUSION: The 3D chromatin architecture in B cells is similar across pediatric, adult, and EBV-transformed cell lines. This conservation of 3D structure includes regions encompassing autoimmune risk haplotypes. Thus, even for pediatric autoimmune diseases, publicly available adult B cell and cell line datasets may be sufficient for assessing effects exerted in the 3D genomic space.

Humans↗

PubMed2026

Chiron3D: an interpretable deep learning framework for understanding the DNA code of chromatin looping.

MOTIVATION: Three-dimensional folding of the genome into structures such as chromatin loops is essential for gene regulation. Current experimental methods for mapping these structures, like Hi-C and HiChIP, are labor-intensive and require repeated assays to test hypothesized mutation effects. This motivates the need for predictive approaches that reveal the sequence determinants of chromatin loops. RESULTS: In this work, we present a novel and interpretable computational pipeline for predicting CTCF-mediated chromatin loops. We propose Chiron3D, a DNA-only model trained in a cell-type specific manner to predict CTCF HiChIP contact maps. By leveraging pre-trained embeddings from a foundation model, our approach is competitive with baselines that take CTCF ChIP-seq as additional input, while enabling nucleotide-level attribution to the input DNA sequence. Using our framework, we provide likely mechanistic insights into the physical control of loop dynamics. Specifically, we find that the strength of the loop extrusion anchorage site is largely governed by the amount and binding affinity of CTCF sites at the boundaries. Furthermore, we reveal that loop stability is regulated by the amount of intra-loop CTCF binding sites, where fewer intra-loop sites are associated with greater loop stability. Using targeted, single-nucleotide edit simulations with Chiron3D, we show that both loop strength and stability can be precisely controlled. Together, these results provide novel mechanistic insights into the physical control of genome organization and highlight the potential of decoding the DNA sequence logic in silico. AVAILABILITY: The Chiron3D pipeline is made available at https://github.com/BoevaLab/Chiron3D.

Chromatin↗

PubMed2025

Phasing single-molecule nano-NOMe-seq reveals chromatin state heterogeneity in the context of transcription and long-range interactions.

A central challenge in molecular biology is determining how 3D chromatin architecture, particularly enhancer-promoter looping and insulating CTCF-mediated interactions, influences gene transcription in individual cells, which has significant implications for healthy and diseased states. To overcome current limitations in imaging and genomic technologies, we developed a cluster-based phasing strategy using long read nano-NOMe-seq to link distinct CTCF binding states-captured at the single molecule level-to the transcriptional status of genes. By stitching partially overlapping long reads and clustering them by shared GpC-accessibility patterns, we stratify CTCF into graded binding states on individual molecules, classify RNA polymerase states at promoters/gene bodies, and infer when spatially separated loci are coordinately activated and occupy loop-competent configurations on the same molecules. When applied to Sox2, Hoxa, and Klf1 regions, cluster-based nano-NOMe-seq phasing reveals how specific topologies bias polymerase behavior and multi-locus activity in ways that bulk assays or locus-engineered imaging cannot fully capture.

Journal Article↗

PubMed2025

Deciphering acquired resistance mechanisms to sustained auxin-inducible protein degradation in cells and mice.

Targeted protein degradation is a favorable strategy for studying the immediate downstream effects of protein loss-of-function. An appealing platform among these technologies is the auxin-inducible degron (AID) system. Although this system has been applied extensively to cell and animal models, degradation resistance to long-term auxin treatment has not been studied. With the advent of the new AID2 system, cellular toxicity due to the high concentrations of auxin required in the original AID1 system is no longer a concern, making it possible to study protein degradation over extended periods. In this study, we derived multiple miniAID-tagged knock-in human cell lines and a Ctcf-miniAID knock-in mouse strain to investigate mechanisms of degradation resistance. We revealed four independent resistance mechanisms, including a nonsense mutation in the CTCF coding sequence that removed the miniAID peptide, a missense point mutation in the miniAID coding region that disrupted ubiquitin complex targeting, and silencing of the OsTIR1 adaptor protein. Resistance to auxin degradation was also acquired in mouse primary CtcfminiAID/miniAID knock-in B-ALL cells through missense mutations of the OsTIR1(F74G) protein in vivo and ex vivo. In summary, our innovative study expands our understanding of the AID system and cautions careful consideration of design for future applications in mammalian system.

CTCF↗

PubMed2026

Single-allele chromatin tracing reveals cytokine-dependent super-enhancer repositioning in CD4+ T cells.

Naive CD4+ T cells interpret cytokine cues to commit to T helper lineages. Here, we examined the impact of cytokines on the Ets1-Fli1 locus, which encodes paralogous transcription factors essential for T cell effector responses. Epigenomic and chromatin interaction profiling in double-positive (DP) thymocytes defined a T cell super-enhancer and a CTCF-bound boundary. Chromatin tracing at single-allele resolution revealed concurrent multi-way interactions among Ets1, Fli1, and the super-enhancer coupled to transcription. Deleting the CTCF boundary decompacted the locus without altering Ets1 expression or T cell development, whereas deleting the super-enhancer drew Ets1 and Fli1 closer; promoter proximity increased Ets1-Fli1 co-expression. In CD4+ Th1 cells, cytokines increased multi-way interactions and repositioned the super-enhancer toward the geometric center, activating both paralogs. Super-enhancer deletion rendered Th1 cells structurally and transcriptionally DP like. Thus, cytokines can drive lineage-specific gene activation by repositioning a super-enhancer, providing a mechanistic framework for how noncoding variants at the Ets1-Fli1 locus contribute to CD4+ T cell-mediated immune disorders.

Animals↗

PubMed2026

Methylome profiling of SetDB1-deficient ESCs reveals coordinated epigenetic cross-talk during pluripotency.

SetDB1 is best known for catalyzing H3K9me3, but it also influences H3K27me3 deposition, CTCF-binding, and DNA methylation (DNAme). Given the interplay between DNAme and the other epigenetic features, we profiled DNAme following Setdb1 knockout (KO) in ground-state and serum-grown mouse embryonic stem cells (ESCs) to illuminate DNAme-dependent and -independent functions of SetDB1. Time-course whole-genome bisulfite sequencing of serum-grown ESCs shows that nearly half of SetDB1 binding sites are enriched with DNAme and H3K9me3, primarily at retrotransposons. Upon Setdb1 KO, both H3K9me3 and DNAme are reduced, with DNAme rapidly removed at many sites by TET enzymes. Some retrotransposons, primarily IAPs, are TET-resistant and lose DNAme slowly via passive dilution. Notably, SetDB1-mediated regulation of H3K27me3, CTCF-binding, and SMAD3 are uncoupled from the DNAme-H3K9me3 axis, and from each other. AlphaFold modeling and co-immunoprecipitation mass spectrometry suggest this uncoupling involves competitive binding to distinct SetDB1 protein domains, highlighting the complex coordination underlying SetDB1 functions.

AlphaFold modeling↗

PubMed2023

3D genome mapping identifies subgroup-specific chromosome conformations and tumor-dependency genes in ependymoma.

Ependymoma is a tumor of the brain or spinal cord. The two most common and aggressive molecular groups of ependymoma are the supratentorial ZFTA-fusion associated and the posterior fossa ependymoma group A. In both groups, tumors occur mainly in young children and frequently recur after treatment. Although molecular mechanisms underlying these diseases have recently been uncovered, they remain difficult to target and innovative therapeutic approaches are urgently needed. Here, we use genome-wide chromosome conformation capture (Hi-C), complemented with CTCF and H3K27ac ChIP-seq, as well as gene expression and DNA methylation analysis in primary and relapsed ependymoma tumors, to identify chromosomal conformations and regulatory mechanisms associated with aberrant gene expression. In particular, we observe the formation of new topologically associating domains ('neo-TADs') caused by structural variants, group-specific 3D chromatin loops, and the replacement of CTCF insulators by DNA hyper-methylation. Through inhibition experiments, we validate that genes implicated by these 3D genome conformations are essential for the survival of patient-derived ependymoma models in a group-specific manner. Thus, this study extends our ability to reveal tumor-dependency genes by 3D genome conformations even in tumors that lack targetable genetic alterations.

Child↗