DNA damage hotspots for the Top2i "ICRF193"
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE256090 | GEO | 2024/04/17
REPOSITORIES: GEO
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Project description:Single strand breaks (SSBs) represent one of the most common types of DNA damage yet not much is known about the genome landscapes of this type of DNA lesions in mammalian cells. Here, we found that SSBs are more likely to occur in certain positions of the human genome — SSB hotspots — in different cells of the same cell type and in different cell types. We hypothesize that the hotspots are likely to represent biologically relevant breaks. And, we found that the hotspots had a prominent tendency to be enriched in the immediate vicinity of transcriptional start sites (TSSs). We show that these hotspots are not likely to represent technical artifacts, or be caused by common mechanisms previously found to cause DNA cleavage at promoters, such as apoptotic DNA fragmentation or topoisomerase type II (TOP2) activity. Therefore, such TSS-associated hotspots could potentially be generated using a novel mechanism, that could involve preferential cleavage at cytosines, and their existence is consistent with recent studies suggesting a complex relationship between DNA damage and regulation of gene expression.
2022-08-18 | GSE190735 | GEO
Project description:We recently developed high-throughput sequencing approaches, eXcision Repair sequencing (XR-seq) and Damage-seq, to generate genome-wide mapping of DNA damage formation and excision repair, respectively, with single-nucleotide resolution. Here, we adopted time-course XR-seq data to profile UV-induced excision repair dynamics, paired with Damage-seq data to quantify the overall induced DNA damage. We identified genome-wide repair hotspots that are subject to exemplified amount of repair very soon after UV irradiation. We show that such repair hotspots do not result from hypersensitivity to DNA damage and are thus not damage hotspots. We find that the earliest repair occur preferentially in promoters and enhancers from open-chromatin regions. The repair hotspots are also significantly enriched for frequently interacting regions and super-enhancers, both of which are hotspots for local chromatin interactions. We further extend the interrogation of chromatin organization to DNA replication timing and conclude that early-repair hotspots are enriched for early-replication domains. Collectively, we report genome-wide early-repair hotspots of UV-induced damage, in association with chromatin states and epigenetic compartmentalization of the human genome.
2020-04-09 | GSE148303 | GEO
Project description:Resolution and formation of facultative heterochromatin is essential to development, reprogramming, and oncogenesis. The mechanisms underlying these changes are poorly understood due to difficulty with interrogating heterochromatin dynamics and structure in vivo. BAF (mSWI/SNF) ATP-dependent chromatin remodeling complexes are known to promote chromatin accessibility. As the function of topoisomerase IIa (TOP2A) is largely dependent on BAF complexes in embryonic stem (ES) cells, we tested whether TOP2 was involved in BAF-mediated resolution of heterochromatin by performing ATAC-seq on ES cells treated with the TOP2 inhibitor ICRF-193, Brg1 (the primary ATPase subunit of esBAF complexes) conditional knockout cells, and Baf53a (a non-catalytic subunit dispensable for in vitro remodeling) conditional knockout cells. We found that TOP2 synergizes with BAF complexes genome-wide to resolve facultative heterochromatin to accessible chromatin at a large number of regulatory elements.
2017-03-01 | GSE94039 | GEO
Project description:In human leukemia, lineage-specific genes represent predominant targets of deletion, with lymphoid-specific genes frequently affected in lymphoid leukemia and myeloid-specific genes in myeloid leukemia. To investigate the basis of lineage-specific alterations, we analyzed global DNA damage in primary B-cell precursors expressing leukemia-inducing oncogenes by ChIP-Seq. We identified >1000 sensitive regions, of which B-lineage-specific genes constitute the most prominent targets. Identified hotspots at B-lineage genes relate to DNA-DSBs, affect genes that harbor genomic lesions in human leukemia, and associate with ectopic deletion in successfully transformed cells. We further show that most identified regions overlap with gene bodies of highly expressed genes, and that induction of a myeloid lineage phenotype in transformed B-cell precursors promotes de novo DNA damage at myeloid loci. Hence, we demonstrate that lineage-specific transcription predisposes lineage-specific genes in transformed B-cell precursors to DNA damage, which is likely to promote the frequent alteration of lineage-specific genes in human leukemia.
2017-02-13 | GSE80682 | GEO
Project description:Mistakes in the maintenance of CG methylation is a source of heritable epimutations in plants. Multigenerational surveys indicate that the rate of these stochastic events varies substantially across the genome, with some regions harboring localized “epimutation hotspots”. Using Arabidopsis as a model, we show that epimutation hotspots are indexed by a specific set of chromatin states (CS) that map to sub-regions of gene body methylation genes. Although these regions comprise only ~12% of all CGs in the genome, they account for ~63% of all epimutation events per unit time. Molecular profiling revealed that these regions contain unique sequence features, harbor steady-state intermediate methylation levels, and act as putative targets of antagonistic DNA methylation pathways. We further demonstrate that experimentally-induced shifts in steady-state methylation in these hotspot regions are sufficient to significantly alter local epimutation intensities. Our work thus lays foundation for dissecting the molecular mechanisms of epimutation hotspots in plants.
2021-12-02 | GSE178684 | GEO
Project description:Here we have used a combination of advanced proteomics and genomics approaches to investigate the extent and mechanisms of transcription factor cross-talk at genomic hotspots. We identify ~12,000 transcription factor hotspots in the early phase of adipogenesis, and we find evidence of both simultaneous and sequential binding of transcription factors at these regions. We demonstrate for the first time that hotspots are highly enriched in large super-enhancer regions and that these drive the early adipogenic reprogramming of gene expression. Our results indicate that cooperativity between transcription factors at the level of hotspots as well as super-enhancers is very important for enhancer activity and transcriptional reprogramming. Thus, hotspots and super-enhancers constitute important regulatory hubs integrating external stimuli on chromatin. Genome-wide profiling of transcription factor and co-factor binding, epigenomic marks, and gene expression in 3T3-L1 pre-adipocytes.
2014-04-17 | E-GEOD-56872 | biostudies-arrayexpress
Project description:DNA Double Strand Breaks (DSBs) are a deleterious product of genotoxic agents or radiotherapy. Despite the inherent chromatin localization of DSBs, the literature has largely ignored the effect of local chromatin or histone post translational modifications (PTMs) on DSB induction or recognition especially in a therapy-relevant setting. Analysis of epigenetic linkages to the DNA Damage Response are challenging owing to the random nature of exogenous DSB induction. Here, we directly measure stochastic DNA damage induced by ionizing radiation (IR) and infer relationships between basal epigenetic states and cellular ability to detect DSBs. Contrary to the expected uniform localization of DSBs and γH2AX, we show that DSB recognition is separate from DSB induction and that both processes are dependent on the local chromatin milieu. In general, actively transcribed regions contain more γH2AX than heterochromatic regions suggesting a link between transcription and the DDR. In contrast to previous studies, we suggest that transcription proximal to DNA damage is necessary for early DSB detection and suggest a requirement for transcription mediated repair in genome maintenance. Finally, we reveal a dual effect of the repressive mark H3K27me3 on the DNA damage response. While basal H3K27me3 attenuates γH2AX deposition, transcribed regions recruit H3K27me3 following DSB induction possibly as an obligate step in DSB recognition. We uncover epigenetic determinants of DSB recognition and suggest new mechanisms by which the epigenome direct DNA repair. Our findings suggest new targets for radio-adjuvant therapy and reframe the current stochastic model of radiotherapy induced damage.
2021-12-31 | GSE181934 | GEO
Project description:Meiotic recombination, crucial for proper chromosome segregation and genome evolution, is initiated by programmed DNA double-strand breaks (DSBs) in budding and fission yeasts and likely all sexually reproducing species. In fission yeast, DSBs occur up to several hundred times more frequently at special sites, called hotspots, than in other regions of the genome. What distinguishes hotspots from cold regions is a major unsolved problem, although transcription factors determine some hotspots. We report here the discovery that three coiled-coil proteins -- Rec25, Rec27, and Mug20 -- bind essentially all hotspots with unprecedented, high specificity even without DSB formation. These small proteins are components of linear elements, are related to synaptonemal complex proteins, and are essential for nearly all DSBs at most hotspots. Our results indicate that these hotspot determinants activate or stabilize the DSB-forming protein Rec12 (Spo11 homolog) rather than promote its binding to hotspots. We propose here a new paradigm for hotspot determination and crossover control by linear element proteins.
2012-12-26 | GSE43121 | GEO
Project description:Meiotic recombination, crucial for proper chromosome segregation and genome evolution, is initiated by programmed DNA double-strand breaks (DSBs) in budding and fission yeasts and likely all sexually reproducing species. In fission yeast, DSBs occur up to several hundred times more frequently at special sites, called hotspots, than in other regions of the genome. What distinguishes hotspots from cold regions is a major unsolved problem, although transcription factors determine some hotspots. We report here the discovery that three coiled-coil proteins -- Rec25, Rec27, and Mug20 -- bind essentially all hotspots with unprecedented, high specificity even without DSB formation. These small proteins are components of linear elements, are related to synaptonemal complex proteins, and are essential for nearly all DSBs at most hotspots. Our results indicate that these hotspot determinants activate or stabilize the DSB-forming protein Rec12 (Spo11 homolog) rather than promote its binding to hotspots. We propose here a new paradigm for hotspot determination and crossover control by linear element proteins.
2012-12-26 | GSE43118 | GEO
Project description:Here we have used a combination of advanced proteomics and genomics approaches to investigate the extent and mechanisms of transcription factor cross-talk at genomic hotspots. We identify ~12,000 transcription factor hotspots in the early phase of adipogenesis, and we find evidence of both simultaneous and sequential binding of transcription factors at these regions. We demonstrate for the first time that hotspots are highly enriched in large super-enhancer regions and that these drive the early adipogenic reprogramming of gene expression. Our results indicate that cooperativity between transcription factors at the level of hotspots as well as super-enhancers is very important for enhancer activity and transcriptional reprogramming. Thus, hotspots and super-enhancers constitute important regulatory hubs integrating external stimuli on chromatin.
2014-04-17 | GSE56872 | GEO