DNA G-quadruplexes are transcription factor binding hot spots in human chromatin
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PROVIDER: PRJNA606017 | ENA |
REPOSITORIES: ENA
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Project description:Gene expression is governed by transcription factors (TFs) that commonly recognize short DNA sequence motifs. However, TF recruitment to genomic target sites in chromatin is complex and many parameters that ultimately dictate binding-site specificity are still unknown. Here, we systematically explore the interaction of TFs with synthetic and endogenous G-quadruplexes (G4s) DNA secondary structures. Our findings reveal that certain TFs are directly recruited to promoters by endogenous G4s with binding affinities comparable to canonical B-DNA binding and that endogenous G4-TF interactions can be disrupted with synthetic small molecule ligands. G4s in promoters are bound by a large number of TFs and associated with high transcriptional activity. This discovery of structure-specific recognition expands our understanding of how TFs regulate gene transcription.
2021-03-24 | GSE145090 | GEO
Project description:Eukaryotic chromosomes are subjected to spontaneous fragmentation even under quick isolation of DNA in a solid phase by strong treatment with 0.1 M EDTA, 1% SDS and proteinase K (1 mg/ml). The long DNA fragments of excised chromosomal DNA were denoted as forum domains. Mostly forum domains are of 50-200 kb in length, although larger domains, up to 500 - 700 kb, are also observed. The domains are delimited by hot spots of double-strand breaks (DSBs). We performed a genome-wide mapping of DSBs in human HEK293T cells cultured cells using Illumina deep sequencing of the termini of forum domains. We found that in rDNA units the hot spots of DSBs are distributed non-randomly. Mostly they are located in IGS.
2014-10-04 | GSE49302 | GEO
Project description:Eukaryotic chromosomes are subjected to spontaneous fragmentation even under quick isolation of DNA in a solid phase by strong treatment with 0.1 M EDTA, 1% SDS and proteinase K (1 mg/ml). The long DNA fragments of excised chromosomal DNA were denoted as forum domains. Mostly forum domains are of 50-200 kb in length, although larger domains, up to 500 - 700 kb, are also observed. The domains are delimited by hot spots of double-strand breaks (DSBs). We performed a genome-wide mapping of DSBs in human HEK293T cells cultured cells using Illumina deep sequencing of the termini of forum domains. We found that in rDNA units the hot spots of DSBs are distributed non-randomly. Mostly they are located in IGS. Genome-wide mapping of DNA DSBs in HEK293T cells
2014-10-04 | E-GEOD-49302 | biostudies-arrayexpress
Project description:Purpose: 253 GSM Samples from GSE32970 and GSE29692 was reanalyzed to find the highly occupied target (HOT) regions of 154 cell lines. Methods: 1. We assigned the binding sites of 542 TFs in 154 cell lines as GSE53962 (Our last submission). 2.We performed a Gaussian kernel density estimation across the genome with a bandwidth of 300 bp, using the centers of each of the TF binding peaks as points. Then, we scanned this density for peaks, and denoted each peak a TF region(Candidate region to find HOT regions).To determine the complexity of the TF region, we summed the Gaussian kernalized distance from the peak to each TF that contributed at least 0.1 to its strength. The TF region around eat peak was derived by finding the maximum distance (in bp) from the peak to a contributing TF, and then adding 150 bp (one half of the bandwidth). Each TF region is centered on the peak, and have a TF complexity value. 3.To define HOT region according to the TF complexity, we required a complexity cutoff for each cell line.To geometrically define the cutoff we first scaled the TF complexity such that the x and y axis were from 0-1. We then found the x axis point for which a line with a slope of 1 was tangent to the curve. We define this point as the cutoff value,TF region whose complexity above this point to be HOT region, and TF region complexity below that point to be lowly occupied target (LOT) regions. Result: Using the binding sites of 542 TFs in 145 cell lines, we assigned a TF complexity score to each TF region corresponding to the number of distinct TFs bound, resulting in HOT regions of 145 cell lines.
2015-01-14 | GSE54296 | GEO
Project description:G-quadruplexes (G4s) are four-stranded nucleic acid structures abundant at gene promoters. They can adopt several distinctive conformations. G4s have been shown to form in the herpes simplex virus-1 (HSV-1) genome during its viral cycle. Here by cross-linking/pull-down assay we identified ICP4, the major HSV-1 transcription factor, as the protein that most efficiently interacts with viral G4s during infection. ICP4 specific and direct binding and unfolding of parallel G4s, including those present in HSV-1 immediate early gene promoters, induced transcription in vitro and in infected cells. This mechanism was also exploited by ICP4 to promote its own transcription. Proximity ligation assay allowed visualization of G4-protein interaction at the single selected G4 in cells. G4 ligands inhibited ICP4 binding to G4s. Our results indicate the existence of a well-defined G4-viral protein network that regulates the productive HSV-1 cycle. They also point to G4s as elements that recruit transcription factors to activate transcription in cells.
2021-09-10 | PXD024743 | Pride
Project description:G-quadruplexes (G4s) are noncanonical DNA secondary structures formed through the self-association of guanines. They are distributed genome-widely and participate in multiple biological processes including gene transcription, and quadruplex-targeted ligands serve as potential therapeutic agents for DNA-targeted therapies. However, the roles of G-quadruplexes in transcriptional regulation remains elusive. Here, we establish a sensitive G4-CUT&Tag method for genome-wide profiling of native G-quadruplexes with high resolution and specificity. We find that native G-quadruplex signals are cell-type specific and are associated with transcriptional regulatory elements with active epigenetic modifications. Promoter-proximal RNA polymerase II pausing promotes native G-quadruplex formation, oppositely, G-quadruplex stabilization by quadruplex-targeted ligands globally reduces RNA polymerase II occupancy at gene promoters as well as nascent RNA synthesis. Moreover, G-quadruplex stabilization modulates chromatin states and impedes transcription initiation via inhibiting the loading of general transcription factors to promoters.Together, these studies reveal a reciprocal regulation between native G-quadruplex dynamics and gene transcription in the genome, which will deepen our knowledge of G-quadruplex biology towards considering therapeutically targeting G-quadruplexes in human diseases.
2021-07-19 | GSE178668 | GEO
Project description: Not available
| S-EPMC8063395 | biostudies-literature
Project description:Native G-quadruplexes Stabilization Impairs Transcription Initiation
| PRJNA739982 | ENA
Project description:Meiotic chromosome architecture called “axis-loop structures” and histone modifications have been demonstrated to regulate the Spo11-dependent formation of DNA double-strand breaks (DSBs) that trigger meiotic recombination. Using genome-wide chromatin immunoprecipitation (ChIP) analyses followed by deep sequencing, we compared the genome-wide distribution of the axis protein Rec8 (the kleisin subunit of meiotic cohesin) with that of oligomeric DNA covalently bound to Spo11, indicative of DSB sites. The frequency of DSB sites is overall constant between Rec8 binding sites. However, DSB cold spots are observed in regions spanning ±0.8 kb around Rec8 binding sites. The axis-associated cold spots are not due to exclusion of Spo11 localization from the axis, since ChIP experiments revealed that substantial Spo11 persists at Rec8 binding sites during DSB formation. Spo11 fused with Gal4 DNA binding domain (Gal4BD-Spo11) tethered in close proximity (≤0.8 kb) to Rec8 binding sites hardly forms meiotic DSBs, in contrast with other regions. In addition, H3K4 tri-methylation (H3K4me3) remarkably decreases at Rec8 binding sites. These results suggest that reduced histone H3K4me3 in combination with inactivation of Spo11 activity on the axis discourages DSB hot spot formation.
2014-03-31 | GSE52858 | GEO
Project description:Meiotic chromosome architecture called “axis-loop structures” and histone modifications have been demonstrated to regulate the Spo11-dependent formation of DNA double-strand breaks (DSBs) that trigger meiotic recombination. Using genome-wide chromatin immunoprecipitation (ChIP) analyses followed by deep sequencing, we compared the genome-wide distribution of the axis protein Rec8 (the kleisin subunit of meiotic cohesin) with that of oligomeric DNA covalently bound to Spo11, indicative of DSB sites. The frequency of DSB sites is overall constant between Rec8 binding sites. However, DSB cold spots are observed in regions spanning ±0.8 kb around Rec8 binding sites. The axis-associated cold spots are not due to exclusion of Spo11 localization from the axis, since ChIP experiments revealed that substantial Spo11 persists at Rec8 binding sites during DSB formation. Spo11 fused with Gal4 DNA binding domain (Gal4BD-Spo11) tethered in close proximity (≤0.8 kb) to Rec8 binding sites hardly forms meiotic DSBs, in contrast with other regions. In addition, H3K4 tri-methylation (H3K4me3) remarkably decreases at Rec8 binding sites. These results suggest that reduced histone H3K4me3 in combination with inactivation of Spo11 activity on the axis discourages DSB hot spot formation.
2014-03-31 | GSE52862 | GEO