Quantitative Analysis of Telomeric Nucleosomal Compaction following ATRX Depletion
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ABSTRACT:
PROVIDER: PRJNA540852 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR9004660_1.fastq.gz | Fastqsanger.gz | |||
| SRR9004660_2.fastq.gz | Fastqsanger.gz | |||
| SRR9004661_1.fastq.gz | Fastqsanger.gz | |||
| SRR9004661_2.fastq.gz | Fastqsanger.gz | |||
| SRR9004662_1.fastq.gz | Fastqsanger.gz |
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Project description:The goal of this experiment is to determine the effect of ATRX depletion on telomeric chromatin compaction. We adapted the ATAC-seq to quantify telomere chromatin accessibility. By scoring the ratio of sequence reads that contained 3 - 12 tandem telomeric repeats over the total number of reads in wild-type and ATRX deplted cells, our analysis revealed that CRISPR/Cas9-mediated ATRX depletion induces a progressive telomere de-compaction.
2019-08-26 | GSE130640 | GEO
Project description:ATRX is a chromatin remodelling factor found at a wide range of tandemly repeated sequences including telomeres (TTAGGG)n. Acquired mutations in ATRX are found in nearly all tumours which maintain their telomeres via the alternative lengthening of telomere (ALT) pathway and ATRX is known to suppress this pathway. Here we show that recruitment of ATRX to telomeric repeats is dependent on their number, their orientation and, critically, on their transcription. Importantly, the transcribed telomeric repeats form RNA-DNA hybrids (R-loops) whose abundance correlates with the recruitment of ATRX. Here we show loss of ATRX is also associated with an increase in R-loop formation. These findings suggest that the presence of ATRX at telomeres may reflect a central role in suppressing deleterious DNA secondary structures which form at transcribed telomeric repeats, and this may account for the increases in DNA damage, stalling of replication and homology directed repair previously observed upon loss of ATRX function.
2017-09-08 | GSE96768 | GEO
Project description:Through an integration of genomic and proteomic approaches to advance understanding of long noncoding RNAs, we investigate the function of the telomeric transcript, TERRA. By identifying thousands of TERRA target sites in the mouse genome, we demonstrate that TERRA can bind both in cis to telomeres and in trans to genic targets. We then define a large network of interacting proteins, including epigenetic factors, telomeric proteins, and the RNA helicase, ATRX. TERRA and ATRX share hundreds of target genes and are functionally antagonistic at these loci: whereas TERRA activates, ATRX represses gene expression. At telomeres, TERRA competes with telomeric DNA for ATRX binding, suppresses ATRX localization, and ensures telomeric stability. Depleting TERRA increases telomerase activity and induces telomeric pathologies, including formation of telomere-induced DNA damage foci and loss or duplication of telomeric sequences. We conclude that TERRA functions as an epigenomic modulator in trans and as an essential regulator of telomeres in cis.
2017-06-29 | GSE79180 | GEO
Project description:The genome consists of non-B-DNA structures such as G-quadruplexes (G4) that are involved in the regulation of genome stability and transcription. Telomeric-repeat containing RNA (TERRA) is capable of folding into G-quadruplex and interacting with chromatin remodeler ATRX. Here we show that TERRA modulates ATRX occupancy on repetitive sequences and over genes, and maintains DNA G-quadruplex structures at TERRA target and non-target sites in mouse embryonic stem cells. TERRA prevents ATRX from binding to subtelomeric regions and represses H3K9me3 formation. G4 ChIP-seq reveals that G4 abundance decreases at accessible chromatin regions, particularly at transcription start sites (TSS) after TERRA depletion; such G4 reduction at TSS is associated with elevated ATRX occupancy and differentially expressed genes. Loss of ATRX alleviates the effect of gene repression caused by TERRA depletion. Immunostaining analyses demonstrate that knockdown of TERRA diminishes DNA G4 signals, whereas silencing ATRX elevates G4 formation. Our results uncover an epigenetic regulation by TERRA that sequesters ATRX and preserves DNA G4 structures.
2022-11-09 | GSE194038 | GEO
Project description:ATRX is a member of the SWI/SNF family of ATP-dependent chromatin remodellers. In humans, loss of ATRX function in leads to ATRX syndrome, a neurodevelopmental disorder. ATRX mutation in human cell lines is associated with multiple phenotypes including activation of the alternative lengthening of telomere (ALT) pathway, upregulation of retrotransposons and increased sensitivity to replication stress. However, the principal role of ATRX and the reason why its mutation causes such diverse phenotypes is currently unclear. To address this, we studied the role of ATRX in the model organism Caenorhabditis elegans. We find that loss of XNP-1, the C. elegans homologue of ATRX, recapitulates many human phenotypes. In addition, XNP-1 is required to repress the inappropriate activation of germline genes. Importantly, this germline misexpression correlates with most of the phenotypes observed in xnp-1 animals. Seemingly distinct xnp-1 phenotypes such as developmental abnormalities and telomeric defects are both suppressed by mutation of the germline transcription factor gsox-1. These findings suggest that the majority of XNP-1-dependent phenotypes stem from its role in maintaining proper cellular identity, offering insights into the functions of ATRX in humans.
2025-03-17 | GSE292128 | GEO
Project description:Herpes simplex virus 1 (HSV-1) transcribes its genome in a highly coordinated temporal cascade, utilizing the host RNA polymerase II (Pol II). Repression of transcription precedes the cascade's progression in a process requiring viral immediate early (IE) genes, in a phenomenon termed Transient Immediate Early gene Mediated Repression (TIEMR). Given that components of promyelocytic leukaemia nuclear bodies (PML-NBs) are known to rapidly engage incoming HSV-1 genomes, we investigated their potential role in TIEMR regulation. Using siRNA knockdown of PML-NB constituents (PML, DAXX, and ATRX), we unexpectedly observed that ATRX depletion resulted in a significant reduction in nascent viral transcription on viral IE promoters at 1.5 hours post-infection (hpi). ChIP-Seq analysis indicated ATRX is associated with both highly transcriptionally active and transcriptionally restricted regions, indicating that ATRX has diverse functions in the viral genome. We show here that ATRX association with active transcription on IE genes is correlated to the presence of G-quadruplexes (G4s). Drug stabilization of G4s mimicked the effects of ATRX knockdown, significantly reducing transcription initiation on IE genes. These findings suggest that ATRX promotes transcriptional initiation of HSV-1 IE genes by preventing G4 formation. In sum, our results reveal a previously unrecognized pro-transcriptional role for ATRX early in HSV-1 infection.
2025-08-26 | GSE293673 | GEO
Project description:Herpes simplex virus 1 (HSV-1) transcribes its genome in a highly coordinated temporal cascade, utilizing the host RNA polymerase II (Pol II). Repression of transcription precedes the cascade's progression in a process requiring viral immediate early (IE) genes, in a phenomenon termed Transient Immediate Early gene Mediated Repression (TIEMR). Given that components of promyelocytic leukaemia nuclear bodies (PML-NBs) are known to rapidly engage incoming HSV-1 genomes, we investigated their potential role in TIEMR regulation. Using siRNA knockdown of PML-NB constituents (PML, DAXX, and ATRX), we unexpectedly observed that ATRX depletion resulted in a significant reduction in nascent viral transcription on viral IE promoters at 1.5 hours post-infection (hpi). ChIP-Seq analysis indicated ATRX is associated with both highly transcriptionally active and transcriptionally restricted regions, indicating that ATRX has diverse functions in the viral genome. We show here that ATRX association with active transcription on IE genes is correlated to the presence of G-quadruplexes (G4s). Drug stabilization of G4s mimicked the effects of ATRX knockdown, significantly reducing transcription initiation on IE genes. These findings suggest that ATRX promotes transcriptional initiation of HSV-1 IE genes by preventing G4 formation. In sum, our results reveal a previously unrecognized pro-transcriptional role for ATRX early in HSV-1 infection.
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Project description:DAXX and ATRX are tumor suppressor proteins that form a complex with histone H3.3 chaperone and are frequently mutated in cancers with the alternative lengthening of telomeres (ALT), such as pediatric glioblastoma. Rapid loss of function of either DAXX or ATRX are not by themselves sufficient to induce the ALT phenotype. However, cells lacking DAXX or ATRX can be readily selected for ALT-like features. Here, we show that a key feature of ALT selected DAXX and ATRX null glioblastoma cells is the attenuation of p53 function. RNA-seq analysis of DAXX or ATRX null U87 glioblastoma cells with ALT-like features revealed that p53 pathway is among perturbed. ALT-selected DAXX and ATRX-null cells had aberrant response to DNA damaging agent etoposide. Both DAXX and ATRX-null ALT cells showed a loss of p53 binding at a subset of response elements. Complementation of DAXX null cells with wt DAXX rescued p53 binding and transcription, while the tumor associated mutation L130R, that disrupts ATRX binding, was incapable of rescuing p53 chromatin binding. We show that histone H3.3 binding is reduced in DAXX-null cells especially at subtelomeric p53 binding sites and telomere repeats. These findings indicate that DAXX and ATRX function to enable p53 chromatin binding through modulation of histone H3.3 binding, especially at sub-telomeric sites.
2022-07-19 | GSE186442 | GEO
Project description:DAXX and ATRX are tumor suppressor proteins that form a complex with histone H3.3 chaperone and are frequently mutated in cancers with the alternative lengthening of telomeres (ALT), such as pediatric glioblastoma. Rapid loss of function of either DAXX or ATRX are not by themselves sufficient to induce the ALT phenotype. However, cells lacking DAXX or ATRX can be readily selected for ALT-like features. Here, we show that a key feature of ALT selected DAXX and ATRX null glioblastoma cells is the attenuation of p53 function. RNA-seq analysis of DAXX or ATRX null U87 glioblastoma cells with ALT-like features revealed that p53 pathway is among perturbed. ALT-selected DAXX and ATRX-null cells had aberrant response to DNA damaging agent etoposide. Both DAXX and ATRX-null ALT cells showed a loss of p53 binding at a subset of response elements. Complementation of DAXX null cells with wt DAXX rescued p53 binding and transcription, while the tumor associated mutation L130R, that disrupts ATRX binding, was incapable of rescuing p53 chromatin binding. We show that histone H3.3 binding is reduced in DAXX-null cells especially at subtelomeric p53 binding sites and telomere repeats. These findings indicate that DAXX and ATRX function to enable p53 chromatin binding through modulation of histone H3.3 binding, especially at sub-telomeric sites.
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Project description:DAXX and ATRX are tumor suppressor proteins that form a complex with histone H3.3 chaperone and are frequently mutated in cancers with the alternative lengthening of telomeres (ALT), such as pediatric glioblastoma. Rapid loss of function of either DAXX or ATRX are not by themselves sufficient to induce the ALT phenotype. However, cells lacking DAXX or ATRX can be readily selected for ALT-like features. Here, we show that a key feature of ALT selected DAXX and ATRX null glioblastoma cells is the attenuation of p53 function. RNA-seq analysis of DAXX or ATRX null U87 glioblastoma cells with ALT-like features revealed that p53 pathway is among perturbed. ALT-selected DAXX and ATRX-null cells had aberrant response to DNA damaging agent etoposide. Both DAXX and ATRX-null ALT cells showed a loss of p53 binding at a subset of response elements. Complementation of DAXX null cells with wt DAXX rescued p53 binding and transcription, while the tumor associated mutation L130R, that disrupts ATRX binding, was incapable of rescuing p53 chromatin binding. We show that histone H3.3 binding is reduced in DAXX-null cells especially at subtelomeric p53 binding sites and telomere repeats. These findings indicate that DAXX and ATRX function to enable p53 chromatin binding through modulation of histone H3.3 binding, especially at sub-telomeric sites.
2022-07-19 | GSE186440 | GEO