G-Quadruplex DNA suppresses Transcription during DNA Replication [CUT&Tag]
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ABSTRACT:
PROVIDER: PRJNA1310565 | ENA |
REPOSITORIES: ENA
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Project description:G-quadruplex DNA suppresses transcription during DNA replication
| PRJNA1214877 | ENA
Project description:G-quadruplex DNA (G4-DNA) structures play crucial but incompletely understood roles in coordinating DNA replication and transcription. Here, we investigate the dynamics of G4-DNA during DNA replication and its functional interplay with transcription machinery in synchronized tumor cells. Using a double-thymidine block to arrest cells in early S phase, we profile G4-DNA structures and associated transcription factors through CUT&Tag, while monitoring transcriptional changes via PRO-seq. To mechanistically dissect these relationships, we perturb the system by overexpressing G4-DNA helicases (DHX36 and BRIP1), treating with the G4-destabilizing agent PhpC, and knocking down the novel G4-binding protein RFC3. Our integrated analysis reveals how G4-DNA spatially and temporally regulates replication-transcription coupling, with important implications for understanding genome stability in cancer. These findings provide new insights into the role of G4-DNA as a regulatory nexus between DNA replication and gene expression.
2025-09-10 | GSE306391 | GEO
Project description:G-Quadruplex DNA suppresses Transcription during DNA Replication [PRO-Seq]
| PRJNA1310554 | ENA
Project description:In eukaryotic cells, although the B-form double helix is the predominant structure of DNA, various non-B-form DNA structures, including G-quadruplex DNA (G4-DNA), are also widely present. For a long time, G4-DNA has been thought to impede DNA replication due to its unique spatial conformation. However, this study demonstrates that S phase G4-DNA accumulation, far from being a passive byproduct, actively functions as a critical safeguard for genomic stability. Contrary to the traditional view of G4-DNA as a replication barrier, its physiological increase during Early S phase minimizes impact on replication itself. Instead, S phase G4-DNA specifically suppresses transcription by stabilizing the negative elongation factor (NELF) complex, thereby preventing transcription-replication conflicts (TRCs) by spatiotemporally segregating transcription and replication. Replication Factor C3 (RFC3), a component of the replication machinery, directly binds and stabilizes G4-DNA to promote its S phase accumulation. Disruption of RFC3 function or G4-DNA unwinding during S phase releases transcriptional suppression, exacerbating TRCs.
2025-01-29 | GSE287896 | GEO
Project description:G-quadruplex DNA (G4-DNA) structures play crucial but incompletely understood roles in coordinating DNA replication and transcription. Here, we investigate the dynamics of G4-DNA during DNA replication and its functional interplay with transcription machinery in synchronized tumor cells. Using a double-thymidine block to arrest cells in early S phase, we profile G4-DNA structures and associated transcription factors through CUT&Tag, while monitoring transcriptional changes via PRO-seq. To mechanistically dissect these relationships, we perturb the system by overexpressing G4-DNA helicases (DHX36 and BRIP1), treating with the G4-destabilizing agent PhpC, and knocking down the novel G4-binding protein RFC3. Our integrated analysis reveals how G4-DNA spatially and temporally regulates replication-transcription coupling, with important implications for understanding genome stability in cancer. These findings provide new insights into the role of G4-DNA as a regulatory nexus between DNA replication and gene expression.
2025-09-10 | GSE306387 | GEO
Project description:G-quadruplex (or G4) structures are non-canonical DNA structures that form in guanine-rich sequences and threaten genome stability when not properly resolved. G4 unwinding occurs during S phase via an unknown mechanism. Using Xenopus egg extracts, we define a three-step G4 unwinding mechanism that acts during DNA replication. First, the replicative helicase (CMG) stalls at a leading strand G4 structure. Second, the DHX36 helicase mediates the bypass of the CMG past the intact G4 structure, which allows approach of the leading strand to the G4. Third, G4 structure unwinding by the FANCJ helicase enables the DNA polymerase to synthesize past the G4 motif. A G4 on the lagging strand template does not stall CMG, but still requires active DNA replication for unwinding. DHX36 and FANCJ have partially redundant roles, conferring robustness to this pathway. Our data reveal a novel genome maintenance pathway that promotes faithful G4 replication thereby avoiding genome instability.
2022-02-17 | PXD027623 | Pride
Project description:Single-stranded genomic DNA can fold into G-quadruplex (G4) structures or form DNA:RNA hybrids (R loops). Recent evidence suggests that such non-canonical DNA structures affect gene expression, DNA methylation, replication fork progression and genome stability. When and how G4 structures form and are resolved remains unclear. Here we report the use of Cleavage Under Targets and Tagmentation (CUT&Tag) for mapping native G4 in mammalian cell lines at high resolution and low background. Mild native conditions used for the procedure retain more G4 structures and provide a higher signal-to-noise ratio than ChIP-based methods. We determine the G4 landscape of mouse embryonic stem cells (mESC), discovering G4 formation at active and poised promoters and enhancers. We discover that the presence of G4 motifs and G4 structures distinguishes active and primed enhancers in mESCs. Further performing R-loop CUT&Tag, we demonstrate the widespread co-occurence of single-stranded DNA, G4s and R loops, suggesting an intricate interrelation of non-canonical DNA structures, transcription and the formation and turnover of G4s.
2021-04-27 | GSE173103 | GEO
Project description:The G-quadruplex is an alternative DNA structural motif that is considered to be functionally important in the mammalian genome. Herein, we address the hypothesis that G-quadruplex structures can exist within double-stranded genomic DNA using a G-quadruplex-specific probe. An engineered antibody is employed to enrich for DNA containing G-quadruplex structures, followed by deep sequencing to detect and map G-quadruplexes at high resolution in genomic DNA from human breast adenocarcinoma cells. Our high sensitivity structure-based pull-down strategy enables the isolation of genomic DNA fragments bearing a single as well as multiple G-quadruplex structures. Stable G-quadruplex structures are found in sub-telomeres, gene bodies and gene regulatory regions. For a sample of identified target genes, we show that G-quadruplex stabilizing ligands can modulate transcription. These results confirm the existence of G-quadruplex structures and their persistence in human genomic DNA. Four independent libraries have been enriched in DNA G-quadruplex structures using a G-quadruplex-specific probe. One genomic input library was sequenced as control. Deep-sequencing of these libraries allowed the mapping of G-quadruplexes on the genome.
2013-05-08 | E-GEOD-45241 | biostudies-arrayexpress
Project description:We analyze the contribution of ATRX and DAXX to G-quadruplex DNA replication in mESC
2021-05-17 | GSE151056 | GEO
Project description:Human DNA topoisomerase 1 (Top1) is a crucial enzyme responsible for alleviating torsional stress on DNA during transcription and replication, thereby maintaining genome stability. Previous researches had found that non-working Top1 interacted extensively with chromosomal DNA in human cells. However, the reason for its retention on chromosomal DNA remained unclear. In this study, we discovered a close association between Top1 and chromosomal DNA, specifically linked to the presence of G-quadruplex (G4) structures. G4 structures, formed during transcription, trap Top1 and hinder its ability to relax neighboring DNAs. Disruption of the Top1-G4 interaction using G4 ligand relieved the inhibitory effect of G4 on Top1 activity, resulting in a further reduction of R-loop levels in cells. Additionally, the activation of Top1 through the use of a G4 ligand enhanced the toxicity of Top1 inhibitors towards cancer cells. Our study uncovers a negative regulation mechanism of human Top1 and highlights a novel pathway for activating Top1.
2024-01-01 | GSE239690 | GEO