Project description:Using 4C-Seq experimental procedure we have characterized, in cultured chicken lymphoid and erythroid cells, genome-wide patterns of spatial contacts of several CpG islands scattered along the chromosome 14. A clear tendency for interaction of CpG islands present within the same and different chromosomes has been observed. Accordingly, preferential spatial contacts between Sp1 binding motifs, and other GC-rich genomic elements including DNA sequence motifs capable to form G-quadruplexes were demonstrated. On the other hand, an anchor placed in gene/CpG islands-poor area was found to form spatial contacts with other gene/CpG islands-poor areas within chromosome 14 and other chromosomes. These results corroborate the two compartments model of interphase chromosome spatial organization and suggest that clustering of CpG islands harboring promoters and origins of DNA replication constitutes an important determinant of the 3D organization of eukaryotic genome in the cell nucleus. Using ChIP-Seq experimental procedure we have mapped genome-wide the CTCF deposition sites in chicken lymphoid and erythroid cells subjected to the 4C analysis. A good correlation between the density of these sites and the level of 4C signals was observed for the anchors located in CpG islands. It is thus possible that CTCF contributes to the clustering of CpG islands revealed in our experiments. Using ChIP-Seq experimental procedure we have mapped genome-wide the CTCF deposition sites in chicken lymphoid and erythroid cells subjected to the 4C analysis. CTCF deposition sites in chicken lymphoid and erythroid (induced and non-induced) cells.
Project description:Using 4C-Seq experimental procedure we have characterized, in cultured chicken lymphoid and erythroid cells, genome-wide patterns of spatial contacts of several CpG islands scattered along the chromosome 14. A clear tendency for interaction of CpG islands present within the same and different chromosomes has been observed. Accordingly, preferential spatial contacts between Sp1 binding motifs, and other GC-rich genomic elements including DNA sequence motifs capable to form G-quadruplexes were demonstrated. On the other hand, an anchor placed in gene/CpG islands-poor area was found to form spatial contacts with other gene/CpG islands-poor areas within chromosome 14 and other chromosomes. These results corroborate the two compartments model of interphase chromosome spatial organization and suggest that clustering of CpG islands harboring promoters and origins of DNA replication constitutes an important determinant of the 3D organization of eukaryotic genome in the cell nucleus. Using ChIP-Seq experimental procedure we have mapped genome-wide the CTCF deposition sites in chicken lymphoid and erythroid cells subjected to the 4C analysis. A good correlation between the density of these sites and the level of 4C signals was observed for the anchors located in CpG islands. It is thus possible that CTCF contributes to the clustering of CpG islands revealed in our experiments.
Project description:Using 4C-Seq experimental procedure we have characterized, in cultured chicken lymphoid and erythroid cells, genome-wide patterns of spatial contacts of several CpG islands scattered along the chromosome 14. A clear tendency for interaction of CpG islands present within the same and different chromosomes has been observed. Accordingly, preferential spatial contacts between Sp1 binding motifs, and other GC-rich genomic elements including DNA sequence motifs capable to form G-quadruplexes were demonstrated. On the other hand, an anchor placed in gene/CpG islands-poor area was found to form spatial contacts with other gene/CpG islands-poor areas within chromosome 14 and other chromosomes. These results corroborate the two compartments model of interphase chromosome spatial organization and suggest that clustering of CpG islands harboring promoters and origins of DNA replication constitutes an important determinant of the 3D organization of eukaryotic genome in the cell nucleus. Using ChIP-Seq experimental procedure we have mapped genome-wide the CTCF deposition sites in chicken lymphoid and erythroid cells subjected to the 4C analysis. A good correlation between the density of these sites and the level of 4C signals was observed for the anchors located in CpG islands. It is thus possible that CTCF contributes to the clustering of CpG islands revealed in our experiments.
Project description:Using 4C-Seq experimental procedure we have characterized, in cultured chicken lymphoid and erythroid cells, genome-wide patterns of spatial contacts of several CpG islands scattered along the chromosome 14. A clear tendency for interaction of CpG islands present within the same and different chromosomes has been observed. Accordingly, preferential spatial contacts between Sp1 binding motifs, and other GC-rich genomic elements including DNA sequence motifs capable to form G-quadruplexes were demonstrated. On the other hand, an anchor placed in gene/CpG islands-poor area was found to form spatial contacts with other gene/CpG islands-poor areas within chromosome 14 and other chromosomes. These results corroborate the two compartments model of interphase chromosome spatial organization and suggest that clustering of CpG islands harboring promoters and origins of DNA replication constitutes an important determinant of the 3D organization of eukaryotic genome in the cell nucleus. Using ChIP-Seq experimental procedure we have mapped genome-wide the CTCF deposition sites in chicken lymphoid and erythroid cells subjected to the 4C analysis. A good correlation between the density of these sites and the level of 4C signals was observed for the anchors located in CpG islands. It is thus possible that CTCF contributes to the clustering of CpG islands revealed in our experiments. We applied 4C-seq to map long-range interactions of a CpG island harboring promoter of a housekeeping gene NPRL3 on a genome-wide scale in DT40 and HD3 cell lines in chicken (Gallus gallus). Two replicates per cell line were sequenced in paired-end mode with a depth of 45-64 million reads. We next performed additional 4C experiments on HD3 cells with different 4C anchors. In three experiments anchors were placed on different CpG island on the chromosome 14 that have demonstrated a strong interaction with the NPRL3 anchor (anchors near TSR3, TRAP1, PPL genes). In the forth experiment (anchor GENE-Des) the anchor was placed in a gene-poor area that did not interact with the NPRL3 promoter. The libraries for all anchors were pooled and sequenced in paired-end mode with a total depth of 75 million reads. Anchor NPRL3: two replicates for HD3 and two replicates for DT40 cell lines. Other anchors (TSR3, GENE-Des, TRAP1, PPL): two replicates, pooled library
Project description:Extensive changes in DNA methylation are common in cancer and may contribute to oncogenesis through transcriptional silencing of tumor suppressor genes. Genome-scale studies have yielded important insights into these changes, but have focused on CpG islands or gene promoters. We used whole-genome bisulfite sequencing (Bisulfite-Seq) to comprehensively profile a primary human colorectal tumor and adjacent-normal colon tissue at single-basepair resolution. Regions of focal hypermethylation in the tumor were located primarily at CpG islands and were concentrated within regions of long-range (>100 kb) hypomethylation. These hypomethylated domains covered nearly half the genome and coincided with late replication and attachment to the nuclear lamina in human cell lines. The confluence of hypermethylation and hypomethylation within these domains was confirmed in 25 diverse colorectal tumors with matched adjacent tissue. We propose that widespread DNA methylation changes in cancer are linked to silencing programs orchestrated by the 3D organization of chromatin within the nucleus. dbGAP study: phs000385 Primary tissue samples sequenced using 76-bp bisulfite sequencing (WGBS or Methyl-seq) using the Illumina GAII platform. Two independent libraries were constructed for each sample, and these libraries were combined into a single data file for each sample.
Project description:Extensive changes in DNA methylation are common in cancer and may contribute to oncogenesis through transcriptional silencing of tumor suppressor genes. Genome-scale studies have yielded important insights into these changes, but have focused on CpG islands or gene promoters. We used whole-genome bisulfite sequencing (Bisulfite-Seq) to comprehensively profile a primary human colorectal tumor and adjacent-normal colon tissue at single-basepair resolution. Regions of focal hypermethylation in the tumor were located primarily at CpG islands and were concentrated within regions of long-range (>100 kb) hypomethylation. These hypomethylated domains covered nearly half the genome and coincided with late replication and attachment to the nuclear lamina in human cell lines. The confluence of hypermethylation and hypomethylation within these domains was confirmed in 25 diverse colorectal tumors with matched adjacent tissue. We propose that widespread DNA methylation changes in cancer are linked to silencing programs orchestrated by the 3D organization of chromatin within the nucleus. dbGAP study: phs000385
Project description:Methylation of CpG islands associated with genes can affect the expression of the proximal gene, and methylation of non associated CpG islands correlates to genomic instability. This epigenetic modification has been shown to be important in many pathologies, from development and disease to cancer. We report the development of a novel high-resolution microarray that detects the methylation status of over 25,000 CpG islands in the human genome. Experiments were performed to demonstrate low system noise in the methodology and that the array probes have a high signal to noise ratio. Methylation measurements between different cell lines were validated demonstrating the accuracy of measurement. We then identified alterations in CpG islands, both those associated with gene promoters, as well as non-promoter associated islands in a set of breast and ovarian tumors. We demonstrate that this methodology accurately identifies methylation profiles in cancer and in principle it can differentiate any CpG methylation alterations and can be adapted to analyze other species.
Project description:Methylation of CpG islands associated with genes can affect the expression of the proximal gene, and methylation of non associated CpG islands correlates to genomic instability. This epigenetic modification has been shown to be important in many pathologies, from development and disease to cancer. We report the development of a novel high-resolution microarray that detects the methylation status of over 25,000 CpG islands in the human genome. Experiments were performed to demonstrate low system noise in the methodology and that the array probes have a high signal to noise ratio. Methylation measurements between different cell lines were validated demonstrating the accuracy of measurement. We then identified alterations in CpG islands, both those associated with gene promoters, as well as non-promoter associated islands in a set of breast and ovarian tumors. We demonstrate that this methodology accurately identifies methylation profiles in cancer and in principle it can differentiate any CpG methylation alterations and can be adapted to analyze other species.