Neurospora crassa
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ABSTRACT:
PROVIDER: PRJNA283990 | ENA |
REPOSITORIES: ENA
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Project description:Methylated lysine 27 on histone H3 (H3K27me) marks repressed "facultative heterochromatin", including developmentally regulated genes in plants and animals. The mechanisms responsible for localization of H3K27me are largely unknown, perhaps in part because of the complexity of epigenetic regulatory networks. We used a relatively simple model organism bearing both facultative and constitutive heterochromatin, Neurospora crassa, to explore possible interactions between elements of heterochromatin. In higher eukaryotes, reductions of H3K9me3 and DNA methylation in constitutive heterochromatin have been variously reported to cause redistribution of H3K27me3. In Neurospora, we found that elimination of any member of the DCDC H3K9 methylation complex (DIM-5, DIM-7, CUL4, DDB1/DIM-8 or DIM-9) caused massive changes in the distribution of H3K27me; regions of facultative heterochromatin lost H3K27me3 while regions that are normally marked by H3K9me3 became methylated at H3K27. Elimination of DNA methylation by deletion of the DNA methyltransferase gene, dim-2, had no obvious effect on the distribution of H3K27me. Elimination of HP1, which "reads" H3K9me3, also caused major changes in the distribution of H3K27me, indicating that HP1 is important for normal localization of facultative heterochromatin. Because loss of HP1 caused redistribution of H3K27me2/3 but not H3K9me3, these normally non-overlapping marks became superimposed. Indeed, mass spectrometry revealed substantial cohabitation of H3K9me3 and H3K27me2 on H3 molecules from an hpo strain. Loss of H3K27me machinery (e.g. the methyltransferase SET-7) did not impact constitutive heterochromatin, but partially rescued the slow growth of the DCDC mutants, suggesting that the poor growth of these mutants is partly attributable to ectopic H3K27me. Altogether, our findings with Neurospora clarify interactions of facultative and constitutive heterochromatin in eukaryotes.
2015-11-03 | GSE68897 | GEO
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.
2016-10-27 | GSE82222 | GEO
Project description:Heterochromatin remodeling is critical for various cell processes. In particular, the “loss of heterochromatin” phenotype in cellular senescence engages with the progress of aging and age-related disorders. Although biological processes of senescent cells including senescence-associated heterochromatin foci (SAHF) formation, chromosome compaction and entry into senescence have been closely associated with high-order chromatin structure. the relationship between the high-order chromatin organization and the loss of heterochromatin phenotype during senescence has not been fully understood. By using senescent and late senescent fibroblasts induced by DNA damage harboring the “loss of heterochromatin” phenotype, we observed progressive 3D reorganization of heterochromatin during senescence. Facultative and constitutive heterochromatin marked by H3K27me3 and H3K9me3, respectively, showed different alterations. Facultative heterochromatin tends to switch from the repressive B-compartment to the active A-compartment, whereas constitutive heterochromatin shows no significant changes at the compartment level but enhanced interactions between themselves. Interestingly, both types show increased chromatin accessibility and gene expression leakage during senescence. Furthermore, increased chromatin accessibility in potential CTCF binding sites accompanies by the establishment of novel loops in constitutive heterochromatin. Finally, we also observed aberrant expression of repetitive elements, including LTR (long terminal repeat) and satellite classes. Overall, facultative and constitutive heterochromatin show multiscale but distinct alterations in the 3D map, meanwhile they also share the same features of increased chromatin accessibility and gene expression leakage. This study provides an epigenomic map of heterochromatin reorganization during senescence.
2019-12-31 | GSE133292 | GEO
Project description:Development in higher organisms requires selective gene silencing, directed in part by di-/tri-methylation of lysine 27 on histone H3 (H3K27me2/3). Knowledge of the cues that control formation of such repressive Polycomb domains is extremely limited. We exploited natural and engineered chromosomal rearrangements in the fungus Neurospora crassa to elucidate the control of H3K27me2/3. Analyses of H3K27me2/3 in strains bearing chromosomal rearrangements revealed both position-dependent and position-independent facultative heterochromatin. We found that proximity to chromosome ends is necessary to maintain, and sufficient to induce, transcriptionally repressive, subtelomeric H3K27me2/3. We ascertained that such telomere-proximal facultative heterochromatin requires native telomere repeats and found that a short array of ectopic telomere repeats, (TTAGGG)17, can induce a large domain (~225 kb) of H3K27me2/3. This provides an example of a cis-acting sequence that directs H3K27 methylation. Our findings provide new insight into the relationship between genome organization and control of heterochromatin formation.
2017-12-29 | GSE104019 | GEO
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
2023-11-22 | GSE228395 | GEO
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
2023-11-22 | GSE248254 | GEO
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
2023-11-22 | GSE228160 | GEO
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
2023-11-22 | GSE227816 | GEO
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
2023-11-22 | GSE229179 | GEO
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
2023-11-22 | GSE247575 | GEO