Set1/COMPASS repels heterochromatin invasion at euchromatic sites by disrupting Suv39/Clr4 activity and nucleosome stability
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ABSTRACT:
PROVIDER: PRJNA588170 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR10416469.fastq.gz | Fastqsanger.gz | |||
| SRR10416470.fastq.gz | Fastqsanger.gz | |||
| SRR10416471.fastq.gz | Fastqsanger.gz | |||
| SRR10416472.fastq.gz | Fastqsanger.gz | |||
| SRR10416473.fastq.gz | Fastqsanger.gz |
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Project description:Protection of euchromatin from invasion by gene-repressive heterochromatin is critical for cellular health and viability. In addition to constitutive loci such as pericentromeres and subtelomeres, heterochromatin can be found interspersed in gene-rich euchromatin, where it regulates gene expression pertinent to cell fate. While heterochromatin and euchromatin are globally poised for mutual antagonism, the mechanisms underlying precise spatial encoding of heterochromatin containment within euchromatic sites remain opaque. We investigated ectopic heterochromatin invasion by manipulating the fission yeast mating type locus boundary using a single-cell spreading reporter system. We found that heterochromatin repulsion is locally encoded by Set1/COMPASS on certain actively transcribed genes and that this protective role is most prominent at heterochromatin islands, small domains interspersed in euchromatin that regulate cell fate specifiers. Sensitivity to invasion by heterochromatin, surprisingly, is not dependent on Set1 altering overall gene expression levels. Rather, the gene-protective effect is strictly dependent on Set1's catalytic activity. H3K4 methylation, the Set1 product, antagonizes spreading in two ways: directly inhibiting catalysis by Suv39/Clr4 and locally disrupting nucleosome stability. Taken together, these results describe a mechanism for spatial encoding of euchromatic signals that repel heterochromatin invasion.
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Project description:We report global occupancy of H3K9me2 and H3K4me3 in wild-type S. pombe and two mutant backgrounds - the deletion of heterochromatin antagonist epe1 and the double mutant absent epe1 and the H3K4 methyltransferase set1
2020-08-24 | GSE140067 | GEO
Project description:Heterochromatin formation in Schizosaccharomyces pombe requires the spreading of histone 3 (H3) Lysine 9 (K9) methylation (me) from nucleation centers by the H3K9 methylase, Suv39/Clr4, and the reader protein, HP1/Swi6. To accomplish this, Suv39/Clr4 and HP1/Swi6 have to associate with nucleosomes both nonspecifically, binding DNA and octamer surfaces and specifically, via recognition of methylated H3K9 by their respective chromodomains. However, how both proteins avoid competition for the same nucleosomes in this process is unclear. Here, we show that phosphorylation tunes the nucleosome affinity of HP1/Swi6 such that it preferentially partitions onto Suv39/Clr4’s trimethyl product rather than its unmethylated substrates. Preferential partitioning enables efficient conversion from di-to trimethylation on nucleosomes in vitro and H3K9me3 spreading in vivo. Together, our data suggests that phosphorylation of HP1/Swi6 creates a regime that relieves competition with the “read-write” mechanism of Suv39/Clr4 for productive heterochromatin spreading.
2024-12-02 | GSE271394 | GEO
Project description:In eukaryotes, the Suv39 family of proteins tri-methylate lysine 9 of histone H3 (H3K9me) to form constitutive heterochromatin. However, how Suv39 proteins are nucleated at heterochromatin is not fully described. In the fission yeast, current models posit that Argonaute1-associated small RNAs (sRNAs) nucleate the sole H3K9 methyltransferase, Clr4/SUV39H, to centromeres. Here, we show that in the absence of all sRNAs and H3K9me, the Mtl1 and Red1 core (MTREC)/PAXT complex nucleates Clr4/SUV39H at a heterochromatic long noncoding RNA (lncRNA) at which the two H3K9 deacetylases, Sir2 and Clr3, also accumulate by distinct mechanisms. Iterative cycles of H3K9 deacetylation and methylation spread Clr4/SUV39H from the nucleation center in an sRNA-independent manner, generating a basal H3K9me state. This is acted upon by the RNAi machinery to augment and amplify the Clr4/H3K9me signal at centromeres to establish heterochromatin. Overall, our data reveal that lncRNAs and RNA quality control factors can nucleate heterochromatin and function as epigenetic silencers in eukaryotes.
2024-05-16 | PXD039519 | Pride
Project description:Eukaryotic chromatin is organized into either silenced heterochromatin or relaxed euchromatin regions, which controls the accessibility of transcriptional machinery and thus regulates gene expression. In fission yeast, Schizosaccharomyces pombe, Set1 is the sole H3K4 methyltransferase and is mainly enriched at the promoters of actively transcribed genes. In contrast, Clr4 methyltransferase initiates H3K9 methylation, which has long been regarded as a hallmark of heterochromatic silencing. Lsd1 and Lsd2 are two highly conserved H3K4 and H3K9 demethylases. As these histone-modifying enzymes perform critical roles in maintaining histone methylation patterns and, consequently, gene expression profiles, cross-regulations among these enzymes are parts of the complex regulatory networks. Thus, elucidating the mechanisms that govern their signaling and mutual regulations remains crucial. Here, we demonstrated that C-terminal truncation mutants, lsd1-∆HMG and lsd2-∆C, do not compromise the integrity of the Lsd1/2 complex but impair their chromatin-binding capacity at the promoter region of target genomic loci. We identified the protein-protein interactions between Lsd1/2 and Raf2 or Swd2, which are the subunits of the Clr4 complex (CLRC) and Set1-associated complexes (COMPASS), respectively. We showed that Clr4 and Set1 modulate the protein levels of Lsd1 and Lsd2 in opposite ways through the ubiquitin-proteasome-dependent pathway. During heat stress, the protein levels of Lsd1 and Lsd2 are upregulated in a Set1-dependent manner. The increase in protein levels is crucial for differential gene expression under stressed conditions. Together, our results support a cross-regulatory model by which Set1 and Clr4 methyltransferases control the protein levels of Lsd1/2 demethylases to shape the dynamic chromatin landscape.
2023-11-16 | GSE246596 | GEO
Project description:Eukaryotic chromatin is organized into either silenced heterochromatin or relaxed euchromatin regions, which controls the accessibility of transcriptional machinery and thus regulates gene expression. In fission yeast, Schizosaccharomyces pombe, Set1 is the sole H3K4 methyltransferase and is mainly enriched at the promoters of actively transcribed genes. In contrast, Clr4 methyltransferase initiates H3K9 methylation, which has long been regarded as a hallmark of heterochromatic silencing. Lsd1 and Lsd2 are two highly conserved H3K4 and H3K9 demethylases. As these histone-modifying enzymes perform critical roles in maintaining histone methylation patterns and, consequently, gene expression profiles, cross-regulations among these enzymes are parts of the complex regulatory networks. Thus, elucidating the mechanisms that govern their signaling and mutual regulations remains crucial. Here, we demonstrated that C-terminal truncation mutants, lsd1-∆HMG and lsd2-∆C, do not compromise the integrity of the Lsd1/2 complex but impair their chromatin-binding capacity at the promoter region of target genomic loci. We identified the protein-protein interactions between Lsd1/2 and Raf2 or Swd2, which are the subunits of the Clr4 complex (CLRC) and Set1-associated complexes (COMPASS), respectively. We showed that Clr4 and Set1 modulate the protein levels of Lsd1 and Lsd2 in opposite ways through the ubiquitin-proteasome-dependent pathway. During heat stress, the protein levels of Lsd1 and Lsd2 are upregulated in a Set1-dependent manner. The increase in protein levels is crucial for differential gene expression under stressed conditions. Together, our results support a cross-regulatory model by which Set1 and Clr4 methyltransferases control the protein levels of Lsd1/2 demethylases to shape the dynamic chromatin landscape.
2023-11-16 | GSE246595 | GEO
Project description:The stimulation of trimethylation of histone H3 lysine 4 (H3K4) by H2B monoubiquitination (H2Bub) has been widely studied with multiple mechanisms proposed for this form of histone crosstalk. Cps35/Swd2 within COMPASS is considered to bridge these processes. However, a truncated form of Set1 (762-Set1) is reported to function in H3K4 trimethylation without interacting with Cps35/Swd2, and such crosstalk is attributed to the n-SET domain of Set1 and its interaction with the Cps40/Spp1 subunit of COMPASS. Here, we use biochemical, structural, in vivo, and ChIP-seq approaches to demonstrate that Cps40/Spp1 and the n-SET domain of Set1 are required for the stability of Set1 and not the crosstalk. Furthermore, the apparent wild-type levels of H3K4 trimethylation (H3K4me3) in the 762-Set1 strain is due to rogue methylase activity of this mutant resulting in the mislocalization of H3K4me3 from the promoter-proximal regions to gene bodies and intergenic regions. We have also performed detailed screens and identified yeast strains lacking H2Bub, but containing intact H2Bub enzymes, that have normal levels of H3K4me3, suggesting that ubiquitination may not directly stimulate COMPASS, but rather works in a context of the PAF and Rad6/Bre1 complexes. Our study demonstrates that the ubiquitination machinery and Cps35/Swd2 function to focus COMPASS’ H3K4me3 activity at promoter-proximal regions in a context dependent manner. ChIP-Seq for H3K4ME3 in S. cerevisie wild-type strains and strains expressing a truncated form of Set1: aa762-1080 Set1. H3K4ME3 ChIP-Seq was also compared for wild-type, leo1 knockout, and chd1 knockout strains
2014-01-09 | E-GEOD-53241 | biostudies-arrayexpress
Project description:Survival in quiescence requires the euchromatic deployment of Clr4/SUV39H by Argonaute-associated small RNAs
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Project description:Cellular quiescence (G0) is a ubiquitous stress response through which cells enter a state of reversible dormancy, acquiring distinct properties including reduced metabolism, resistance to stress and long life. G0 entry involves dramatic changes to the chromatin landscape and transcriptional program of cells, but the mechanisms coordinating these processes remain poorly understood. Using the fission yeast, here we track the G0-associated chromatin and transcriptional changes temporally. We show that as cells enter G0, their survival and global gene expression programs become increasingly dependent on Clr4/SUV39H, the sole histone H3 lysine 9 (H3K9) methyltransferase, and RNA interference (RNAi) proteins. Notably, G0 entry results in RNAi-dependent H3K9 methylation of several euchromatic regions, prior to which Argonaute 1-associated small RNAs from these regions emerge. Overall our data reveal a new function for constitutive heterochromatin proteins in establishing the global G0 transcriptional program and suggest that stress-induced alterations in Argonaute-associated sRNAs can specify the deployment of transcriptional regulatory proteins to unique sites in eukaryotic genomes.
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