Persistent accumulation of unrepaired DNA damage in rat cortical neurons: nuclear organization and ChIP-seq analysis of damaged DNA
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ABSTRACT:
ORGANISM(S): Rattus norvegicus
PROVIDER: GSE112930 | GEO | 2019/03/23
REPOSITORIES: GEO
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Project description:Persistent accumulation of unrepaired DNA damage in rat cortical neurons: nuclear organization and ChIP-seq analysis of damaged DNA
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Project description:H2AX phosphorylation at Ser139 (gH2AX) is an early key event of the DNA damage response (DDR) following DNA double strand breaks (DSB) induction. Although gH2AX distribution has been extensively used as a damage marker, genome-wide investigation of the subsequent DNA repair has been poorly addressed. Here we present ChIP-Seq-based distributions of Histone H3, H2AX and gH2AX under physiological conditions in HeLa cells. Additionally the same histones were studied after a single exposure to 10 Gy X-ray at 0.5, 3 and 24 hours post irradiation
2017-04-17 | GSE60526 | GEO
Project description:Oxidative DNA damage in neurons activates a DNA damage response (DDR) to promote repair. Under a chronic oxidative environment these processes may be altered and promote accumulation of unrepaired DNA damage and continued activation of a DDR, leading to apoptosis or senescence activation. Accumulation of oxidative DNA damage are features of brain ageing and neurodegeneration but the effects of persistent DNA damage in neurons are not well characterised. We developed a model of persistent oxidative DNA damage in human neurons in vitro (LUHMES) by exposing them to a sub-lethal concentration of hydrogen peroxide (H2O2) following a "single stress" and “double stress” protocols. We characterised the neuronal transcriptome under these circumstances using microarray analysis.
2023-11-04 | GSE160841 | GEO
Project description:Bacteria, yeast and human cancer cells possess mechanisms of mutagenesis upregulated by stress responses. Stress-inducible mutagenesis potentially accelerates adaptation, and may provide important models for mutagenesis that drives cancers, host pathogen interactions, antibiotic resistance and possibly much of evolution generally. In Escherichia coli repair of double-strand breaks (DSBs) becomes mutagenic, using low-fidelity DNA polymerases under the control of the SOS DNA-damage response and RpoS general stress response, which upregulate and allow the action of error-prone DNA polymerases IV (DinB), II and V to make mutations during repair. Pol IV is implied to compete with and replace high-fidelity DNA polymerases at the DSB-repair replisome, causing mutagenesis. We report that up-regulated Pol IV is not sufficient for mutagenic break repair (MBR); damaged bases in the DNA are also required, and that in starvation-stressed cells, these are caused by reactive-oxygen species (ROS). First, MBR is reduced by either ROS-scavenging agents or constitutive activation of oxidative-damage responses, both of which reduce cellular ROS levels. The ROS promote MBR other than by causing DSBs, saturating mismatch repair, oxidizing proteins, or inducing the SOS response or the general stress response. We find that ROS drive MBR through oxidized guanines (8-oxo-dG) in DNA, in that overproduction of a glycosylase that removes 8-oxo-dG from DNA prevents MBR. Further, other damaged DNA bases can substitute for 8-oxo-dG because ROS-scavenged cells resume MBR if either DNA pyrimidine dimers or alkylated bases are induced. We hypothesize that damaged bases in DNA pause the replisome and allow the critical switch from high fidelity to error-prone DNA polymerases in the DSB-repair replisome, thus allowing MBR. The data imply that in addition to the indirect stress-response controlled switch to MBR, a direct cis-acting switch to MBR occurs independently of DNA breakage, caused by ROS oxidation of DNA potentially regulated by ROS regulators.
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Project description:Translocations, that occur when two DNA Double Strand breaks (DSBs) are abnormally rejoined, represent highly deleterious genome rearrangements favoring cancer apparition and progression. However, the mechanisms that drive their formation are yet poorly deciphered. One prerequisite for translocation is the juxtaposition of two distant DSBs, an event that would be favored if DSB cluster, i.e. are brought together in close spatial proximity within the nucleus. Whether DSB cluster in higher eukaryotes has been subjected to a strong controversy over the past decade, due to conflicting results obtained using microscopy based methods1-9. Here we used for the first time a high throughput chromosome conformation capture assay (Capture Hi-C10) to investigate DSB clustering. We unambiguously found that DSBs do cluster in human nuclei but only when induced in transcriptionally active genes. Clustering of damaged genes mainly occur during the G1 cell cycle phase and coincide with delayed repair. Moreover DSB clustering depends on the MRN complex, as well as the Formin 2 (FMN2) nuclear actin organizer and the LINC (LInker of Nuclear and Cytoplasmic skeleton) complex, suggesting that active mechanisms promote DSB clustering. This work reveals that when damaged, active genes exhibit a very peculiar behavior compared to the rest of the genome, being mostly left unrepaired and clustered in G1 while being repaired by homologous recombination in post-replicative cells.
2017-04-19 | E-MTAB-4846 | biostudies-arrayexpress
Project description:Purpose: determine if gH2AX and H3.3 are enriched at unsynapsed regions of chromosomes involved in translocations in mouse germ line (meiotic prophase I) Methods: testes were isolated from 4-week or 6-week old heterozygous carriers of a single Robertsonian translocation RB(8;12) or 3 Robertsonian translocations RB(8;12), RB(1;3) and RB(9;14) and controls. ChIP assays were conducted as described in Smagulova 2011. Experiments done in triplicate. Results: We find enrichment of gH2AX in the proximal gene-rich regions of translocation-associated chromosomes and reduced enrichment of gH2AX and H3.3 at sex chromosomes
2016-11-19 | GSE75221 | GEO
Project description:Reduced FOXF1 Links Unrepaired DNA Damage to Pulmonary Arterial Hypertension
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Project description:Neurons are highly vulnerable to DNA damage induced by genotoxic agents such as topoisomerase activity, oxidative stress, ionizing radiation (IR) and chemotherapeutic drugs. To avert the detrimental effects of DNA lesions in genome stability, transcription and apoptosis, neurons activate robust DNA repair mechanisms. However, defective DNA repair with accumulation of unrepaired DNA are at the basis of brain ageing and several neurodegenerative diseases. Understanding the mechanisms by which neurons tolerate DNA damage accumulation as well as defining the genomic regions that are more vulnerable to DNA damage or refractory to DNA repair and therefore constitute potential targets in neurodegenerative diseases are essential issues in the field. In this work we investigated the nuclear topography and organization together with the genome-wide distribution of unrepaired DNA in rat cortical neurons 15 days upon IR. About 5% of non-irradiated and 55% of irradiated cells accumulate unrepaired DNA within persistent DNA damage foci (PDDF) of chromatin. These PDDF are featured by persistent activation of DNA damage/repair signaling, lack of transcription and localization in repressive nuclear microenvironments. Interestingly, the chromatin insulator CTCF is concentrated at the PDDF boundaries, likely contributing to isolate unrepaired DNA from intact transcriptionally active chromatin. By confining damaged DNA, PDDF would help preserving genomic integrity and preventing the production of aberrant proteins encoded by damaged genes.ChIP-seq analysis of genome-wide γH2AX distribution revealed a number of genomic regions enriched in γH2AX signal in IR-treated cortical neurons. Some of these regions are in close proximity to genes encoding essential proteins for neuronal functions and human neurodegenerative disorders such as epm2a (Lafora disease), serpini1 (familial encephalopathy with neuroserpin inclusion bodies) and il1rpl1 (mental retardation, X-linked 21). Persistent γH2AX signal close to those regions suggests that nearby genes could be either more vulnerable to DNA damage or more refractory to DNA repair.
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Project description:Parkinson disease (PD) is a neurodegenerative disease believed to initiate in the brainstem and then spread throughout the brain. The mechanism by which this occurs is not yet fully understood, but here we show that damaged mitochondrial DNA (mtDNA) plays an important role in this process, which can be initiated by dysregulation of the IFNb/IFNAR signalling pathway. We report that lack of neuronal IFNb/IFNAR, which is associated to the development of PD, causes oxidization, mutation, and deletion in mtDNA. Damaged mtDNA is subsequently extruded extracellularly and can induce PD symptoms like motor and cognitive impairments in healthy mouse brains. It even leads to neurodegeneration in brain regions far from the injection site, suggesting that damaged mtDNA triggers the propagation of PD hallmarks through the brain. We further show that the mechanism by which damaged mtDNA causes pathology in healthy neurons is independent of cGAS and IFNb/IFNAR, but it is mediated by activation of dual Toll-like receptor (TLR)4/9 pathways. Through a proteomic analysis of extracellular vesicles containing the damaged mtDNA, we identified the TLR4 activator Ribosomal Protein S3 (Rps3) and established that Rps3 is a key effector protein involved in damaged mtDNA extrusion and recognition. Collectively, these results reveal a new molecular pathway by which damaged mtDNA can initiate and propagate Parkinson's Disease, paving the way for potential new therapies or disease monitoring.
2023-09-18 | PXD038362 | Pride
Project description:The goal of this experiment was to determine the role of the lncRNA DINO in the DNA damage response in regulating transcription factor occupancy of human fibroblasts. DINO, an inducible long noncoding in respose to DNA damage, is required for cell cycle arrest and induction of several p53 regulated genes. We hypothesized that ATACseq in DINO-depleted cells may uncover a role for DINO in transcription factor recruitment to p53 responsive genes following DNA damage.
2016-09-26 | GSE76417 | GEO