Similar Datasets
Project description:Heterochromatin, typically marked by histone H3 trimethylation at lysine 9 (H3K9me3) or lysine 27 (H3K27me3), represses different protein-coding genes in different cells, as well as repetitive elements. The basis for locus specificity is unclear. Previously, we identified 172 proteins that are embedded in sonication-resistant heterochromatin (srHC) harbouring H3K9me3. Here, we investigate in humans how 97 of the H3K9me3-srHC proteins repress heterochromatic genes. We reveal four groups of srHC proteins that each repress many common genes and repeat elements. Two groups repress H3K9me3-embedded genes with different extents of flanking srHC, one group is specific for srHC genes with H3K9me3 and H3K27me3, and one group is specific for genes with srHC as the primary feature. We find that the enhancer of rudimentary homologue (ERH) is conserved from Schizosaccharomyces pombe in repressing meiotic genes and, in humans, now represses other lineage-specific genes and repeat elements. The study greatly expands our understanding of H3K9me3-based gene repression in vertebrates.
| S-EPMC9248069 | biostudies-literature
Project description:Heterochromatin, typically marked by H3K9me3 or H3K27me3, is key to the repression of genes and repetitive elements. The mechanisms responsible for establishing and maintaining heterochromatin in a locus specific manner are unclear. Heterochromatin restricts cell identity by preventing activation of alternative lineage genes. This barrier can be partially overcome by inducing ectopic transcription factors (TFs) to activate an alternative transcriptional program. However, TFs are impeded by highly restrictive heterochromatin leading to low reprogramming rates and incomplete activation of the target transcriptome. Previously we utilized the heterochromatin property of sonication resistance to identify 172 proteins associated with sonication resistant heterochromatin (srHC) by mass spectrometry (Becker, et al., 2017). We hypothesized that by functionally assessing the srHC proteins and identifying the genes they repress during reprogramming we could improve our understanding of heterochromatin maintenance and learn how to disrupt heterochromatin to enhance reprogramming. Focusing on reprogramming from fibroblasts to induced human hepatocytes (hiHeps) we conducted an siRNA screen of 97 srHC proteins without reprogramming factors (noTF) and with hiHep reprogramming and assessed the impact on the expression of genes located in srHC domains by RNA-seq. We identified enhancer of rudimentary homolog (ERH) as a key regulator of H3K9me3 heterochromatin maintenance. ERH was found to associate broadly with H3K9me3 domains and when depleted caused global changes in H3K9me3 and srHC. Collectively our screen of srHC protein repressive function demonstrates specific functionality of groups of srHC proteins and increases our understanding of H3K9me3 gene repression.
2021-06-24 | GSE154232 | GEO
Project description:Heterochromatin, typically marked by H3K9me3 or H3K27me3, is key to the repression of genes and repetitive elements. The mechanisms responsible for establishing and maintaining heterochromatin in a locus specific manner are unclear. Heterochromatin restricts cell identity by preventing activation of alternative lineage genes. This barrier can be partially overcome by inducing ectopic transcription factors (TFs) to activate an alternative transcriptional program. However, TFs are impeded by highly restrictive heterochromatin leading to low reprogramming rates and incomplete activation of the target transcriptome. Previously we utilized the heterochromatin property of sonication resistance to identify 172 proteins associated with sonication resistant heterochromatin (srHC) by mass spectrometry (Becker, et al., 2017). We hypothesized that by functionally assessing the srHC proteins and identifying the genes they repress during reprogramming we could improve our understanding of heterochromatin maintenance and learn how to disrupt heterochromatin to enhance reprogramming. Focusing on reprogramming from fibroblasts to induced human hepatocytes (hiHeps) we conducted an siRNA screen of 97 srHC proteins without reprogramming factors (noTF) and with hiHep reprogramming and assessed the impact on the expression of genes located in srHC domains by RNA-seq. We identified enhancer of rudimentary homolog (ERH) as a key regulator of H3K9me3 heterochromatin maintenance. ERH was found to associate broadly with H3K9me3 domains and when depleted caused global changes in H3K9me3 and srHC. Collectively our screen of srHC protein repressive function demonstrates specific functionality of groups of srHC proteins and increases our understanding of H3K9me3 gene repression.
2021-06-24 | GSE154214 | GEO
Project description:Heterochromatin, typically marked by H3K9me3 or H3K27me3, is key to the repression of genes and repetitive elements. The mechanisms responsible for establishing and maintaining heterochromatin in a locus specific manner are unclear. Heterochromatin restricts cell identity by preventing activation of alternative lineage genes. This barrier can be partially overcome by inducing ectopic transcription factors (TFs) to activate an alternative transcriptional program. However, TFs are impeded by highly restrictive heterochromatin leading to low reprogramming rates and incomplete activation of the target transcriptome. Previously we utilized the heterochromatin property of sonication resistance to identify 172 proteins associated with sonication resistant heterochromatin (srHC) by mass spectrometry (Becker, et al., 2017). We hypothesized that by functionally assessing the srHC proteins and identifying the genes they repress during reprogramming we could improve our understanding of heterochromatin maintenance and learn how to disrupt heterochromatin to enhance reprogramming. Focusing on reprogramming from fibroblasts to induced human hepatocytes (hiHeps) we conducted an siRNA screen of 97 srHC proteins without reprogramming factors (noTF) and with hiHep reprogramming and assessed the impact on the expression of genes located in srHC domains by RNA-seq. We identified enhancer of rudimentary homolog (ERH) as a key regulator of H3K9me3 heterochromatin maintenance. ERH was found to associate broadly with H3K9me3 domains and when depleted caused global changes in H3K9me3 and srHC. Collectively our screen of srHC protein repressive function demonstrates specific functionality of groups of srHC proteins and increases our understanding of H3K9me3 gene repression.
2021-06-24 | GSE154148 | GEO
Project description:Diverse Heterochromatin-Associated Proteins Repress Distinct Classes of Genes and Repetitive Elements
| PRJNA645455 | ENA
Project description:Diverse Heterochromatin-Associated Proteins Repress Distinct Classes of Genes and Repetitive Elements (RNA-seq)
| PRJNA645208 | ENA
Project description:Diverse Heterochromatin-Associated Proteins Repress Distinct Classes of Genes and Repetitive Elements (srHC-seq)
| PRJNA645456 | ENA
Project description:Diverse Heterochromatin-Associated Proteins Repress Distinct Classes of Genes and Repetitive Elements (ChIP-seq)
| PRJNA645434 | ENA
Project description:In interphase eukaryotic cells, almost all heterochromatin is located adjacent to the nucleolus or to the nuclear lamina, thus defining nucleolus-associated domains (NADs) and lamina-associated domains (LADs), respectively. Here, we determined the first genome-scale map of murine NADs in mouse embryonic fibroblasts (MEFs) via deep sequencing of chromatin associated with purified nucleoli. We developed a Bioconductor package called NADfinder and demonstrated that it identifies NADs more accurately than other peak-calling tools, owing to its critical feature of chromosome-level local baseline correction. We detected two distinct classes of NADs. Type I NADs associate frequently with both the nucleolar periphery and the nuclear lamina, and generally display characteristics of constitutive heterochromatin, including late DNA replication, enrichment of H3K9me3, and little gene expression. In contrast, Type II NADs associate with nucleoli but do not overlap with LADs. Type II NADs tend to replicate earlier, display greater gene expression, and are more often enriched in H3K27me3 than Type I NADs. The nucleolar associations of both classes of NADs were confirmed via DNA-FISH, which also detected Type I but not Type II probes enriched at the nuclear lamina. Type II NADs are enriched in distinct gene classes, including factors important for differentiation and development. In keeping with this, we observed that a Type II NAD is developmentally regulated, and present in MEFs but not in undifferentiated embryonic stem (ES) cells.
| S-EPMC6673712 | biostudies-literature
Project description:During meiosis, the formation of viable haploid gametes from diploid precursors requires that each homologous chromosome pair be properly segregated to produce an exact haploid set of chromosomes. Genetic recombination, which provides a physical connection between homologous chromosomes, is essential in most species for proper homologue segregation. Nevertheless, recombination is repressed specifically in and around the centromeres of chromosomes, apparently because rare centromeric (or pericentromeric) recombination events, when they do occur, can disrupt proper segregation and lead to genetic disabilities, including birth defects. The basis by which centromeric meiotic recombination is repressed has been largely unknown. We report here that, in fission yeast, RNAi functions and Clr4-Rik1 (histone H3 lysine 9 methyltransferase) are required for repression of centromeric recombination. Surprisingly, one mutant derepressed for recombination in the heterochromatic mating-type region during meiosis and several mutants derepressed for centromeric gene expression during mitotic growth are not derepressed for centromeric recombination during meiosis. These results reveal a complex relation between types of repression by heterochromatin. Our results also reveal a previously undemonstrated role for RNAi and heterochromatin in the repression of meiotic centromeric recombination and, potentially, in the prevention of birth defects by maintenance of proper chromosome segregation during meiosis.
| S-EPMC2889303 | biostudies-literature