Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA266684 | ENA |
REPOSITORIES: ENA
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Project description:Transcription restores DNA repair to heterochromatin, Determining regional mutation rates in cancer genomes
| PRJNA266683 | ENA
Project description:<p>Base mutations occur at higher frequencies within heterochromatin and late-replicating DNA. In this study, we show that regional differences in mutation frequency are absent in portions of the genome that are not transcribed within cutaneous squamous cell carcinomas (cSCCs) with an XPC-\- genetic background. The XPC-\- genetic background predicates a loss of global genome nucleotide excision repair (GG-NER), thus our data shows that regional differences in mutation frequency are a result of differential access of DNA repair protein. Unexpectedly, we also note that greater transcription reduces mutations on both strands of genes in heterochromatin, and only to those levels observed in euchromatin, in a XPC-dependent fashion. Therefore, transcription likely reduces mutation prevalence by increasing access to DNA repair proteins. This tripartite relationship between DNA repair, transcription, and chromatin state shows a new cancer risk factor in human populations.</p>
| phs000830 | dbGaP
Project description:UV light is an initiating factor in the etiology of human melanoma due to its production of mutagenic DNA photoproducts, primarily cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts. UV-induced mutations are heterogeneously distributed across melanoma genomes, being enriched, for example, in regions of compact heterochromatin and at active transcription factor binding sites (TFBS). Differential ability of nucleotide excision repair (NER) to remove UV-induced DNA lesions in these regions has been proposed as the primary factor establishing the observed regional differences in melanoma mutation density. However, it is not fully understood to what extent the binding of transcription factors and chromatin structure affect UV damage formation, nor how variations in initial damage levels contribute to mutagenesis. Here, we directly mapped sites of CPD formation across the genome in human cells, and show that variations in UV damage formation, due to primary chromatin structure and transcription factor binding, are strongly correlated with local differences in melanoma mutation density. Analysis of individual transcription factors revealed that the E26 transformation-specific (ETS) family is the major contributor to increased somatic mutation density at TFBS in melanoma, primarily because DNA binding by ETS family transcription factors stimulates the formation of CPD lesions, generating UV damage 'hotspots'. Moreover, many ETS binding sites, including those associated with known cancer genes, are recurrently mutated in human melanomas. These findings establish variable lesion formation as a key contributor to mutation heterogeneity in cancer.
2018-06-21 | GSE103487 | GEO
Project description:Constitutive heterochromatin is responsible for genome repression of DNA enriched in repetitive sequences, telomeres, and centromeres. In higher eukaryotes, constitutive heterochromatin is mostly segregated at the nuclear periphery, where the interaction with the nuclear lamina makes the genome more resistant to transcription. During physiological and pathological premature aging, heterochromatin homeostasis is profoundly compromised. Here we show that LINE-1 (L1) RNA accumulation is an early event in both typical and atypical progeroid syndromes. Depletion of L1 RNA in cells from different progeroid syndrome patients using specific antisense oligonucleotides (ASO) restores the levels of heterochromatin epigenetic marks, reverses DNA methylation age and counteracts the expression of senescence-associated genes. Moreover, proteome profiling involved in senescence phenotype was partially restored upon depletion of LINE-1 RNA in both Hutchinson-Gilford Progeria Syndrome (HGPS) and Werner syndrome (WRN-/-).
2022-11-02 | PXD032944 | Pride
Project description:Human genome stability requires efficient repair of oxidized bases, which is initiated via damage recognition and excision by NEIL1 and other base excision repair (BER) pathway DNA glycosylases (DGs). However, the biological mechanisms underlying detection of damaged bases among the million-fold excess of undamaged bases remain enigmatic. Indeed, mutation rates vary greatly within individual genomes, and lesion recognition by purified DGs in the chromatin context is inefficient. Employing super-resolution microscopy and coimmunoprecipitation assays, we find that acetylated NEIL1 (AcNEIL1), but not its nonacetylated form, is predominantly localized in the nucleus in association with epigenetic marks of uncondensed chromatin. Furthermore, chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) revealed non-random AcNEIL1 binding near transcription start sites of weakly transcribed genes and along highly transcribed chromatin domains. Bioinformatic analyses revealed a striking correspondence between AcNEIL1 occupancy along the genome and mutation rates, with AcNEIL1-occupied sites exhibiting reduced mutations compared to AcNEIL1-free domains, both in cancer genomes and in population variation. Intriguingly, from the evolutionarily-conserved unstructured domain that targets NEIL1 to open chromatin, its damage surveillance of highly oxidation-susceptible sites to preserve essential gene function and to limit instability and cancer likely originated ~500 million years ago during the buildup of free atmospheric oxygen.
2020-11-03 | GSE142324 | GEO
Project description:Protein-DNA interactions are dynamic and these dynamics are an important aspect of chromatin-associated processes such as transcription or replication. Due to a lack of methods to study on- and off-rates across entire genomes, protein-DNA interaction dynamics have not been studied extensively. Here we determine in vivo off-rates for the Saccharomyces cerevisiae chromatin organizing factor Abf1, at 191 sites simultaneously across the yeast genome. Average Abf1 residence times span a wide-range, varying between 4.5 and 37 minutes. Sites with different off-rates are associated with different functional characteristics. This includes their transcriptional dependency on Abf1, nucleosome positioning and the size of the nucleosome-free region, as well as the ability to roadblock RNA polymerase II for termination. The results show how off-rates contribute to transcription factor function and that DIVORSEQ (Determining In Vivo Off-Rates by SEQuencing) is a meaningful way of investigating protein-DNA binding dynamics genome-wide.
2020-06-04 | GSE151692 | GEO
Project description:Protein-DNA interactions are dynamic and these dynamics are an important aspect of chromatin-associated processes such as transcription or replication. Due to a lack of methods to study on- and off-rates across entire genomes, protein-DNA interaction dynamics have not been studied extensively. Here we determine in vivo off-rates for the Saccharomyces cerevisiae chromatin organizing factor Abf1, at 191 sites simultaneously across the yeast genome. Average Abf1 residence times span a wide-range, varying between 4.5 and 37 minutes. Sites with different off-rates are associated with different functional characteristics. This includes their transcriptional dependency on Abf1, nucleosome positioning and the size of the nucleosome-free region, as well as the ability to roadblock RNA polymerase II for termination. The results show how off-rates contribute to transcription factor function and that DIVORSEQ (Determining In Vivo Off-Rates by SEQuencing) is a meaningful way of investigating protein-DNA binding dynamics genome-wide.
2020-06-04 | GSE151468 | GEO
Project description:A CSB-PAF1C axis restores processive transcription elongation after DNA damage repair
| PRJNA591582 | ENA
Project description:The coordinated transcription of genes involves RNA polymerase II enzymes (RNAPII), which pull DNA through their active sites. DNA lesions in transcribed strands block RNAPII elongation and induce a strong transcriptional arrest. The transcription-coupled repair (TCR) pathway ensures the efficient removal of transcription-blocking DNA lesions, but this is not sufficient to overcome this arrest and resume transcription. Through proteomics screens, we find that the TCR-specific CSB protein loads the evolutionary conserved PAF1 complex (PAF1C) onto RNAPII in promoter-proximal regions specifically in response to DNA damage. PAF1C is dispensable for TCR-mediated repair,but is essential to resume RNA synthesis after UV irradiation, suggesting an unexpected uncoupling between DNA repair and transcription restart. Moreover, we find that PAF1C promotes RNAPII pause release in promoter-proximal regions and subsequently acts as a processivity factor that stimulates transcription elongation waves throughout genes. Our findings expose the molecular basis for a non-canonical PAF1C-dependent pathway that restores transcription throughout the human genome after genotoxic stress.
2021-02-28 | PXD016198 | Pride
Project description:Ultraviolet (UV) component of solar radiation impairs genome stability by inducing the formation of pyrimidine-pyrimidone (6-4) photoproducts [(6-4)PPs] in plant genomes. (6-4)PPs disrupt growth and development by interfering with transcription and DNA replication. To resist UV stress, plants employ nucleotide excision repair that excises oligonucleotides containing (6-4)PPs through two subpathways: global and transcription-coupled excision repair (TCR) . Here, we analyzed the genome-wide excision repair-mediated repair of (6-4)PPs in Arabidopsis thaliana and found that (6-4)PPs can be repaired by TCR; however, the main subpathway to remove (6-4)PPs from the genome is global repair. Our analysis showed that open chromatin genome regions are more rapidly repaired than heterochromatin regions, and the repair level peaks at the promoter, transcription start site (TSS) and transcription end site (TES) of genes. Our study revealed that the repair of (6-4)PP in plants showed a distinct genome-wide repair profile compared to the repair of other major UV-induced DNA lesion called cyclobutane pyrimidine dimers (CPDs).
2024-02-15 | GSE243671 | GEO