GTP-dependent regulation of heterochromatin fluctuations at subtelomeric regions in S. cerevisiae
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PROVIDER: PRJNA962489 | ENA |
REPOSITORIES: ENA
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Project description:Analysis of gene expression changes following deletion of SIR genes at subtelomeric region. A total of 4 samples were analyzed : Wild type (BY4742) strain, SIR2 deletion strain, SIR3 deletion strain, SIR4 deletion strain.
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Project description:Facultative heterochromatin in the filamentous fungus Neurospora crassa is identified by the repressive histone mark H3K27me3 and is primarily subtelomeric, while constitutive heterochromatin, marked by the DIM-5-catalzyed H3K9me3, is found at centromeres, telomeres, and smaller dispersed regions. In strains lacking constitutive heterochromatin (e.g., Δdim-5), H3K27me2/3 relocalizes to the regions formerly marked by H3K9me3. H3K27me3 is catalyzed by the SET-7 histone methyltransferase subunit of the Polycomb Repressive Complex 2 (PRC2); another PRC2 member, Neurospora p55 (NPF) regulates subtelomeric H3K27me2/3. Despite the de-repression of >70 genes, a Δset-7 strain has no distinguishable phenotype. To investigate the facultative heterochromatin contribution to genome organization, we performed high-throughput “chromosome conformation capture” (Hi-C) on mutants with impacted H3K27me2/3 deposition. A Δset-7 strain has decreased inter-/intra-subtelomeric contacts among others; this pattern is mirrored in a Δnpf strain, which lacks subtelomeric H3K27me3. In a Δset-7 strain, telomere bundles were often uncoupled from the nuclear membrane and de-repressed genes were subtelomeric. The chromosome conformation of a Δset-7;Δdim-5 double mutant was similar to Δset-7, suggesting that facultative heterochromatin relocalization does not compensate for H3K9me3 loss and rescue the Neurospora genome organization in strains with defective constitutive heterochromatin.
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Project description:The eukaryotic genome is divided into chromosomal domains of heterochromatin and euchromatin. Transcriptionally silent heterochromatin is found at subtelomeric regions, leading to the telomeric position effect (TPE) in yeast, fly and man. Heterochromatin generally initiates and spreads from defined loci, and diverse mechanisms prevent the ectopic spread of heterochromatin into euchromatin. Here, we overexpressed the silencing factor Sir3 at various levels in yeast, and found that Sir3 spreading into Extended Silent Domains (ESD) eventually reached saturation at subtelomeres. We observed that Sir3 spreading into ESDs covered zone associated with specific histone marks in wild-type cells and stopped at zones of histone mark transitions including H3K79 tri-methylation levels. The conserved enzyme Dot1 deposits H3K79 methylation, and we found that it is essential for viability upon overexpression of Sir3, but not of a spreading-defective mutant Sir3A2Q. These data suggest that H3K79 methylation actively blocks Sir3 spreading. Lastly, we demonstrate that our work uncovers previously uncharacterized discrete subtelomeric domains associated with specific chromatin features, that offers a new viewpoint on how to separate subtelomeres from the core chromosome.
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Project description:Dose-dependency of heterochromatin domains reveals subtelomeric structuration in budding yeast
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Project description:Expanding heterochromatin reveals discrete subtelomeric domains delimited by chromatin landscape transitions
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Project description:Subtelomeric chromatin is subject to evolutionarily conserved complex epigenetic regulation and is implicated in numerous aspects of cellular function including formation of heterochromatin, regulation of different stress response pathways, and control of lifespan. Subtelomeric DNA is characterized by the presence of specific repeated segments that serve to propagate silencing activities or to protect chromosomal regions from spreading epigenetic control. Using condition-specific genome wide chromatin immunoprecipitation and expression data, we show that several yeast transcription factors regulate subtelomeric silencing in response to various environmental stimuli through conditional association with proto-silencing regions called X elements. In this context, some factors control the propagation of silencing toward centromeres in response to stimuli affecting stress responses and metabolism, whereas others appear to influence boundaries of silencing, regulating telomere-proximal genes in Y’ elements. The factors implicated here have previously been shown to control adjacent genes at intrachromosomal positions, suggesting dual functionality of the factors and a possible mechanism of coordinating intrachromosomal gene expression with subtelomeric silencing. These data suggest a fundamental mechanism to coordinate telomere biology related to aging and adaptation with cellular environment and the activities of other cellular processes. These are Chip-CHIP data for myc tagged Oaf1p transcription factor from S. cerevisiae grown in the presence or absence of the fatty acid oleate.
2011-05-03 | GSE21852 | GEO
Project description:Subtelomeric chromatin is subject to evolutionarily conserved complex epigenetic regulation and is implicated in numerous aspects of cellular function including formation of heterochromatin, regulation of different stress response pathways, and control of lifespan. Subtelomeric DNA is characterized by the presence of specific repeated segments that serve to propagate silencing activities or to protect chromosomal regions from spreading epigenetic control. Using condition-specific genome wide chromatin immunoprecipitation and expression data, we show that several yeast transcription factors regulate subtelomeric silencing in response to various environmental stimuli through conditional association with proto-silencing regions called X elements. In this context, some factors control the propagation of silencing toward centromeres in response to stimuli affecting stress responses and metabolism, whereas others appear to influence boundaries of silencing, regulating telomere-proximal genes in Y’ elements. The factors implicated here have previously been shown to control adjacent genes at intrachromosomal positions, suggesting dual functionality of the factors and a possible mechanism of coordinating intrachromosomal gene expression with subtelomeric silencing. These data suggest a fundamental mechanism to coordinate telomere biology related to aging and adaptation with cellular environment and the activities of other cellular processes. These are Chip-CHIP data for myc tagged Oaf1p transcription factor from S. cerevisiae grown in the presence or absence of the fatty acid oleate. ChIP-CHIP analysis was performed to determine the genomic distribution of Oaf1p transcription factor in the BY4742 yeast strain after growth in 0.1% glucose, or in the presence of the fatty acid oleate. Three biological replicates for each growth condition (in the presence of low glucose or 5 h after a shift to medium containing oleate as a carbon source). ChIP samples were amplified by PCR, labelled and hybridized to 50-mer tiling arrays covering both strands of the entire yeast genome at a 64 bp resolution.
2011-05-02 | E-GEOD-21852 | biostudies-arrayexpress
Project description:Occupancy profiling of Rec12 during fission yeast meiosis. Facultative heterochromatin regulates gene expression, but its assembly is poorly understood. Previously, we identified facultative heterochromatin islands in the fission yeast genome and found that RNA elimination machinery promotes island assembly at meiotic genes. Here, we report that Taz1, a component of the telomere protection complex Shelterin, is required to assemble heterochromatin islands at regions corresponding to late replication origins that are sites of double-strand break formation during meiosis. The loss of Taz1 and other Shelterin subunits, including Ccq1 that interacts with Clr4/Suv39h, abolishes heterochromatin at late origins and causes defective silencing of associated genes. Moreover, the late origin regulator Rif1 affects heterochromatin at Taz1-dependent islands and subtelomeric regions. We uncover a connection between heterochromatin and replication control, and show that heterochromatin factors affect timing of replication. These analyses implicate Shelterin in facultative heterochromatin assembly at late origins, which has important implications for the maintenance of genome stability and gene regulation. Whole cell extract DNA and DNA recovered by Rec12 ChIP from fission yeast undergoing synchronous meiosis were random-prime PCR amplified and labeled with Cy3 (whole cell extract) or Cy5 (IP DNA) and analyzed using custom 60mer Agilent array that tiles Schizosaccharomyces pombe genome in 300bp intervals alternately on both strands.
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Project description:Occupancy profiling of Shelterin components in fission yeast. Facultative heterochromatin regulates gene expression, but its assembly is poorly understood. Previously, we identified facultative heterochromatin islands in the fission yeast genome and found that RNA elimination machinery promotes island assembly at meiotic genes. Here, we report that Taz1, a component of the telomere protection complex Shelterin, is required to assemble heterochromatin islands at regions corresponding to late replication origins that are sites of double-strand break formation during meiosis. The loss of Taz1 and other Shelterin subunits, including Ccq1 that interacts with Clr4/Suv39h, abolishes heterochromatin at late origins and causes defective silencing of associated genes. Moreover, the late origin regulator Rif1 affects heterochromatin at Taz1-dependent islands and subtelomeric regions. We uncover a connection between heterochromatin and replication control, and show that heterochromatin factors affect timing of replication. These analyses implicate Shelterin in facultative heterochromatin assembly at late origins, which has important implications for the maintenance of genome stability and gene regulation. Whole cell extract DNA and DNA recovered from Taz1 or Rif1-immunoprecipitated chromatin of fission yeast were random-prime PCR amplified and labeled with Cy3 (whole cell extract DNA) or with Cy5 (IP DNA) and analyzed using custom 60mer Agilent array that tiles Schizosaccharomyces pombe genome in 300bp intervals alternately on both strands.
2016-06-09 | E-GEOD-78822 | biostudies-arrayexpress
Project description:ChIP-chip analyses of lysine 9 dimethylated histone H3 in Shelterin mutants. Facultative heterochromatin regulates gene expression, but its assembly is poorly understood. Previously, we identified facultative heterochromatin islands in the fission yeast genome and found that RNA elimination machinery promotes island assembly at meiotic genes. Here, we report that Taz1, a component of the telomere protection complex Shelterin, is required to assemble heterochromatin islands at regions corresponding to late replication origins that are sites of double-strand break formation during meiosis. The loss of Taz1 and other Shelterin subunits, including Ccq1 that interacts with Clr4/Suv39h, abolishes heterochromatin at late origins and causes defective silencing of associated genes. Moreover, the late origin regulator Rif1 affects heterochromatin at Taz1-dependent islands and subtelomeric regions. We uncover a connection between heterochromatin and replication control, and show that heterochromatin factors affect timing of replication. These analyses implicate Shelterin in facultative heterochromatin assembly at late origins, which has important implications for the maintenance of genome stability and gene regulation. Whole cell extract DNA and DNA recovered from H3K9 dimethylated chromatin of fission yeast were random-prime PCR amplified and labeled with Cy3 (whole cell extract) or Cy5 (IP DNA) and analyzed using custom 60mer Agilent array that tiles Schizosaccharomyces pombe genome in 300bp intervals alternately on both strands.
2016-06-09 | E-GEOD-78820 | biostudies-arrayexpress