G-quadruplex DNA suppresses transcription during DNA replication
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1214877 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR32104300_1.fastq.gz | Fastqsanger.gz | |||
| SRR32104300_2.fastq.gz | Fastqsanger.gz | |||
| SRR32104301_1.fastq.gz | Fastqsanger.gz | |||
| SRR32104301_2.fastq.gz | Fastqsanger.gz | |||
| SRR32104302_1.fastq.gz | Fastqsanger.gz |
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Project description:G-Quadruplex DNA suppresses Transcription during DNA Replication [PRO-Seq]
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Project description:G-Quadruplex DNA suppresses Transcription during DNA Replication [CUT&Tag]
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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.
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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 (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.
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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.
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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.
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Project description:Short tracts of trinucleotide repeats with less than 10 repeats are found frequently throughout the genome without any apparent negative impact on DNA replication fork progression or transcription elongation. CGG binding protein 1 (CGGBP1) binds to CGG triplet repeats and has been implicated in multiple cellular processes such as transcription, replication and DNA damage. Here, we show that CGGBP1 binds to human gene promoter sites with short CGG repeat tracts prone to G-quadruplex and R-loop secondary structure formation. Depletion of CGGBP1 in human cells leads to substantial transcriptomic changes which coincides with increased replication fork stalling and transcription-replication conflicts. Consistently, an episomal model locus as well as endogenous candidate genes containing short tracts of CGG repeats show R-loop accumulation and increased RNAPII chromatin occupancy in CGGBP1-depleted cells. Mass spectrometry identifies the DEAD-box helicase DDX41 as a specific interaction partner of CGGBP1, thereby providing mechanistic insight how CGGBP1 can counteract the formation of secondary DNA structures at CGG repeats. Together, our work shows that short trinucleotide repeats are a source of genome-destabilizing secondary structures and cells rely on specific DNA-binding factors to maintain proper transcription and replication progression at short trinucleotide repeats.
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Project description:Topoisomerase I (Top1) is a key enzyme acting at the interface between DNA replication, transcription and mRNA maturation. Here, we show that Top1 suppresses genomic instability in mammalian cells by preventing conflicts between transcription and DNA replication. Using DNA combing and ChIP-on-chip, we found that Top1-deficient cells accumulate stalled replication forks and chromosome breaks in S phase and that breaks occur preferentially at gene-rich regions of the genome. Strikingly, these phenotypes were suppressed by preventing the formation of RNA-DNA hybrids (R-loops) during transcription. Moreover, these defects could be mimicked by depletion of the splicing factor ASF/SF2, which interacts functionally with Top1. Taken together, these data indicate that Top1 prevents replication fork collapse by suppressing the formation of R-loops in an ASF/SF2-dependent manner. We propose that interference between replication and transcription represents a major source of spontaneous replication stress, which could drive genomic instability during early stages of tumorigenesis. Bed files contain the gamma-H2AX enrichment sites described in the paper
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Project description:An Upstream G‐Quadruplex DNA Structure Can Stimulate Gene Transcription
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