Profiling DNA G-quadruplex structures at single-cell level
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE181373 | GEO | 2021/12/08
REPOSITORIES: GEO
Similar Datasets
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: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.
2013-05-08 | GSE45241 | GEO
Project description:Currently, the identification of G4 quadruplexes in vivo depends on a published and widely used G4-ChIP protocol (PMID: 29470465) that uses the anti-G4 antibody to captures the quadruplexes like regular chromatin. This method is challenged by some false positives and false negatives in G4-quadruplex capture. We have developed an antibody capture G4-ChIP (AbC G4-ChIP) method to overcome these challenges. The AbC G4-ChIP achieves (i) minimized in vitro artifacts during the incubation steps, and (ii) capture of G4-quadruplexes which are not protein-bound. We have applied the AbC G4-ChIP to study the regulatory effect of a CGG-repeat binding protein CGGBP1 on G4-quadruplex formation. The AbC G4-ChIP identifies inter-strand G/C-skew as a sequence property associated with CGGBP1-regulated G4-quadruplexes.
2024-03-20 | GSE202456 | GEO
Project description:G-quadruplexes (G4) are non-canonical nucleic acid structures that can form at certain DNA or RNA guanine-rich sequences. G4 motifs are dispersed throughout the genome and considerably enriched at promoters, where they flank the transcription start site (TSS) and cluster at the 5’ end of the first intron, which suggests potential regulatory roles of quadruplexes in transcription. To improve our understanding of these roles, we have associated gene expression with the frequency of canonical G4 motifs near gene promoters and characterized perturbations caused by treatment with three G-quadruplex ligands, Pyridostatin and the two bisquinolinium compounds PhenDC3 and PhenDC6. We show that enrichment of G4 motifs characterizes the most actively transcribed genes, challenging the notion that quadruplexes chiefly exert negative regulation by blocking progress of RNA polymerase. G4 ligand-treatment altered splicing of transcripts at genes enriched for G4 motifs at the 5’-end of intron 1, suggesting that G-quadruplexes in the pre-mRNA can regulate splicing. Furthermore, our analysis also revealed some of the effects of G4 ligand treatment that likely reflect quadruplex-dependent replication stress leading to the induction of transcriptional signatures compatible with impaired cell cycle progression. Collectively, our results support the view that G-quadruplexes typically function as positive regulators of transcription, suggesting that quadruplexes may stabilize promoter architecture to enable efficient transcription. This analysis provides strong support for function of quadruplexes near the promoter as regulators of transcription and splicing.
2020-11-02 | GSE133419 | GEO
Project description:Profiling DNA G-quadruplex structures at single-cell level
| PRJNA751854 | ENA
Project description:To investigate specific G-quadruplex stabilization in the regulation of gene expression and chromatin accessibility, we established HeLa cell lines in which each target g-quadruplexes has been stabilized.
2024-05-25 | GSE255625 | GEO
Project description:G-quadruplex structures in the 5’ UTR of mRNAs are widely considered to suppress translation without affecting transcription. The current study describes the comprehensive analysis of proteins binding to four different G-quadruplex motifs located in mRNAs of the cancer-related genes Bcl-2, NRAS, MMP16, and ARPC2. Following metabolic labeling (Stable Isotope Labeling with Amino acids in Cell culture, SILAC) of proteins in the human cell line HEK293, G-quadruplex binding proteins were enriched by pull-down assays and identified by LC-orbitrap mass spectrometry. We found different patterns of interactions for the G-quadruplex motifs under investigation. While the G-quadruplexes in the mRNAs of NRAS and MMP16 specifically interacted with a small number of proteins, the Bcl-2 and ARPC2 G-quadruplexes exhibited a broad range of proteinaceous interaction partners with 99 and 82 candidate proteins identified in at least two replicates, respectively. Among the interaction partners were many proteins known to bind to RNA, including multiple heterogenous nuclear ribonucleoproteins (hnRNPs). The identified ribosomal proteins are likely to reflect stalling of the ribosome by RNA G-quadruplex structures. In addition, several proteins were identified that have not previously been described to interact with RNA. Gene ontology analysis of the set of candidate proteins revealed that many interaction partners are known to be tumor related. The majority of the identified RNA G-quadruplex interacting proteins are thought to be involved in post-transcriptional processes, particularly in splicing. These findings indicate that protein-G-quadruplex interactions may be relevant to the regulation of mRNA maturation and may play an important role in tumor biology.
2017-11-14 | PXD005761 | Pride
Project description:It is generally thought that splicing factors regulate alternative splicing through binding to RNA consensus sequences. In addition to these linear motifs, RNA secondary structure is emerging as an important layer in splicing regulation. Here we demonstrate that RNA elements with G-quadruplex forming capacity promote exon inclusion. Destroying G-quadruplex forming capacity while keeping G-tracts intact abrogates exon inclusion. Analysis of RNA binding protein footprints revealed that G-quadruplexes are enriched in hnRNPF-binding sites and near hnRNPF-regulated alternatively spliced exons in the human transcriptome. Moreover, hnRNPF regulates an EMT-associated CD44 isoform switch in a G-quadruplex-dependent manner, which results in inhibition of EMT. Mining breast cancer TCGA datasets, we demonstrate that hnRNPF negatively correlates with an EMT gene signature and positively correlates with patient survival. These data suggest a critical role for RNA G-quadruplexes in regulating alternative splicing. Modulation of G-quadruplex structural integrity may control cellular processes important for tumor progression.
2018-01-22 | GSE107542 | GEO
Project description:DNA secondary structures are important for fundamental genome functions such as transcription and replication1. The G-quadruplex (G4) structural motif has been linked to gene regulation2,3 and genome instability4,5 and may be important to cancer development and other diseases6-8. Recently, ~700,000 discrete G4s have been observed in naked human single-stranded genomic DNA using G4-seq, a high-throughput sequencing technique that detects structural features in vitro.9 It is of vital importance to investigate G4 structures within an endogenous chromatin context, which until now remained elusive10,11. Herein, we address this via the development of G4 ChIP-seq, an antibody-based G4 chromatin immunoprecipitation and high-throughput sequencing approach. We identified ~10,000 endogenous G4 structures and show that G4s are predominantly seen in regulatory, nucleosome-depleted, chromatin regions. G4s were enriched in the promoters and 5âUTR regions of highly transcribed genes, particularly in genes related to cancer and in somatic copy number amplifications, such as MYC. Reorganization of the chromatin landscape using a histone deacetylase inhibitor, resulted in de novo G4 formation in new and more prominent regulatory, nucleosome-depleted regions associated with increased transcriptional output. Our findings suggest a striking relationship between promoter nucleosome-depleted regions, G4 formation and elevated transcriptional activity. Comparison between normal human epidermal keratinocytes and their immortalized counterparts revealed a ï¾7-fold greater G4 abundance in immortalized cells, of which 80 % were found in regulatory, nucleosome-depleted regions common to both cell types. Consequently, cells exhibiting more G4s displayed significantly increased transcriptional output and were more sensitive to growth inhibition by a small molecule G4 ligand. Overall, our results provide new mechanistic insights into where and when DNA adopts G4 structure in vivo. Our findings show for the first time that regulatory, nucleosome-depleted chromatin and transcriptional states predominantly shape the endogenous G4 DNA landscape. Two cell lines, treated with entinostat or untreated, analyzed to detect gene expression differences, presence of G-Qudruplexes and chromatin state. Each combination of conditions replicated in duplicates or triplicates.
2016-08-05 | E-GEOD-76688 | biostudies-arrayexpress
Project description:RNA-binding proteins are important regulators of RNA biogenesis and function, and recent work shows that chromatin- and RNA-binding proteins can have regulatory roles in transcription. Several approaches have been developed to predict RNA-binding proteins and to identify them experimentally at large scale, including binding to structural elements as G-quadruplexes. Here, we show that the histone lysine demethylase protein KDM5 can bind to RNA through interaction with G-quadruplexes with high affinity despite neither being categorized as an RNA-binding protein nor identified as a G-quadruplex binding protein across numerous experimental large-scale and computational studies. In addition to characterizing the KDM5 G-quadruplex interaction we show that RNA is directly involved in the formation of KDM5-containing protein complexes. Computational predictions and comparison to other ARID domain containing proteins suggest that the ARID domain is directly interacting with both DNA and RNA across several proteins. Our work highlights that non-canonical aspects of RNA-binding proteins are present, and that G-quadruplex RNA-binding could provide a regulatory mechanism for chromatin-binding proteins with impact on transcription through linking protein complexes within the cell.
2024-04-11 | PXD050767 | Pride