CHARACTERIZATION AND DYNAMICS OF MOUSE PERICENTROMERE-ASSOCIATED DOMAINS
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE65618 | GEO | 2015/04/01
SECONDARY ACCESSION(S): PRJNA274485
REPOSITORIES: GEO
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Project description:Despite recent progress in genome topology knowledge, the role of repeats, comprising the majority of mammalian genomes, remains elusive. Satellites are highly abundant sequences that cluster around centromeres, attract pericentromeric heterochromatin and aggregate into nuclear chromocenters that are assumed to form a repressive compartment in the nucleus to which genes are recruited for silencing. Here we designed a strategy for genome-wide identification of pericentromere-associated domains (PADs) in different mouse cell types. The ~1000 PADs and non-PADs have similar chromatin states in embryonic stem cells. During lineage commitment however chromocenters progressively overlap with constitutively inactive genomic regions at the nuclear periphery. This suggests that chromocenters do not actively recruit PADs but are themselves attracted to inactive chromatin compartments. However, we also found that experimentally induced proximity of an active locus to chromocenters was sufficient to cause gene repression. Collectively, our data suggests that rather than being a driver of nuclear organization, pericentromeric satellite repeats mostly co-segregate with inactive genomic regions to nuclear compartments where they can contribute to stably maintaining the repressed status of proximal chromosomal regions. We performed satellite 4C (sat4C) on mouse primary thymus tissue, pluripotent mouse embryonic stem cells (ESC) and neural precursor cells (NPC) and terminally differentiated astrocytes (AC) that were sequentially derived from these ESC in vitro
2015-04-01 | E-GEOD-65618 | biostudies-arrayexpress
Project description:Non-coding satellite DNA repeats are abundant at the pericentromeric heterochromatin of eukaryotic chromosomes. During interphase, sequence-specific DNA-binding proteins cluster these repeats from multiple chromosomes into nuclear foci known as chromocenters. Despite the pivotal role of chromocenters in cellular processes like genome encapsulation and gene repression, the associated proteins remain incompletely characterized. Here, we use two satellite DNA-binding proteins, D1 and Prod, as baits to characterize the chromocenter-associated proteome in Drosophila embryos, ovaries, and testes through quantitative mass spectrometry. We identify D1- and Prod-associated proteins, including known heterochromatin proteins as well as proteins previously unlinked to satellite DNA or chromocenters, thereby laying the foundation for a comprehensive understanding of cellular functions enabled by satellite DNA repeats and their associated proteins. Interestingly, we find that multiple components of the transposon-silencing piRNA pathway are associated with D1 and Prod in embryos. Using genetics, transcriptomics, and small RNA profiling, we show that flies lacking D1 during embryogenesis exhibit transposon expression and gonadal atrophy as adults. We further demonstrate that this gonadal atrophy can be rescued by mutating the checkpoint kinase, Chk2, which mediates germ cell arrest in response to transposon mobilization. Thus, we reveal that a satellite DNA-binding protein functions during embryogenesis to silence transposons, in a manner that is heritable across later stages of development.
2024-12-11 | GSE283701 | GEO
Project description:Background: Heterochromatin at the pericentromeric repeats in fission yeast is assembled and spread by an RNAi-dependent mechanism, which is coupled to the transcription of non-coding RNA from the repeats by RNA polymerase II. In addition, Rrp6, a component of the nuclear exosome, also contributes to heterochromatin assembly and is coupled to non-coding RNA transcription. The multi-subunit complex Mediator, which directs initiation of RNA polymerase II-dependent transcription, has recently been suggested to function after initiation in processes such as elongation of transcription and splicing. However, the role of Mediator in the regulation of chromatin structure is not well understood. Results: We investigated the role of Mediator in pericentromeric heterochromatin formation and found that deletion of specific subunits of the head domain of Mediator compromised heterochromatin structure. The Mediator head domain was required for Rrp6-dependent heterochromatin nucleation at the pericentromere and for RNAi-dependent spreading of heterochromatin into the neighboring region. In the latter process, Mediator appeared to contribute to efficient processing of siRNA from transcribed non-coding RNA, which was required for efficient spreading of heterochromatin. Furthermore, the head domain directed efficient transcription in heterochromatin. Conclusions: These results reveal a pivotal role for Mediator in multiple steps of transcription-coupled formation of pericentromeric heterochromatin. This observation further extends the role of Mediator to co-transcriptional chromatin regulation. Gene expression profile at exponentially-growing phase.in the fission yeast deletion mutants of pmc6, med20 and dcr1.
2013-08-31 | E-GEOD-43543 | biostudies-arrayexpress
Project description:Background: Heterochromatin at the pericentromeric repeats in fission yeast is assembled and spread by an RNAi-dependent mechanism, which is coupled to the transcription of non-coding RNA from the repeats by RNA polymerase II. In addition, Rrp6, a component of the nuclear exosome, also contributes to heterochromatin assembly and is coupled to non-coding RNA transcription. The multi-subunit complex Mediator, which directs initiation of RNA polymerase II-dependent transcription, has recently been suggested to function after initiation in processes such as elongation of transcription and splicing. However, the role of Mediator in the regulation of chromatin structure is not well understood. Results: We investigated the role of Mediator in pericentromeric heterochromatin formation and found that deletion of specific subunits of the head domain of Mediator compromised heterochromatin structure. The Mediator head domain was required for Rrp6-dependent heterochromatin nucleation at the pericentromere and for RNAi-dependent spreading of heterochromatin into the neighboring region. In the latter process, Mediator appeared to contribute to efficient processing of siRNA from transcribed non-coding RNA, which was required for efficient spreading of heterochromatin. Furthermore, the head domain directed efficient transcription in heterochromatin. Conclusions: These results reveal a pivotal role for Mediator in multiple steps of transcription-coupled formation of pericentromeric heterochromatin. This observation further extends the role of Mediator to co-transcriptional chromatin regulation.
2013-08-31 | GSE43543 | GEO
Project description:The prominent role of pericentromeric Mbp block of 1.688 satellites in hybrid incompatibility, facilitating role of distributed X-linked 1.688 satellites in dosage compensation in males and being as a necessary element for POF recruitment to chromosome X in females led us to further investigate the role of 1.688 satellites and POF in chromosome-wide gene regulation by comparing RNA-seq data from the relevant mutants in comparison to wildtype.
2020-01-30 | GSE136637 | GEO
Project description:Genome wide chromatin maps have shown that spreading repressive histone modifications such as H3K9me3 and H4K20me3 are present on pericentromeric and telomeric repeats and on the inactive X chromosome where H3K27me3 or H3K9me3 alternately modify megabasepair sized domains. However, only a few regions along an autosome of which Homeobox gene clusters are notable examples, have been shown to display spreading of repressive histone modifications. Here we present a ChIP-Chip map of repressive and active histone modifications along mouse Chr.17 in embryonic, fibroblast cells. Our results show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types and their flanking intergenic regions, indicating a negative correlation between H3K27me3 and transcription. However, non-transcribed gene-poor regions also lacked H3K27me3. We therefore performed a low resolution analysis of whole mouse Chr.17 which revealed that H3K27me3 specifically marks megabasepair sized domains that are enriched for genes, SINEs and active histone modifications. These genic H3K27me3 domains alternate with similar sized gene-poor domains that are deficient in active histone modifications, but enriched for LINE and LTR transposons as well as H3K9me3 and H4K20me3. Thus, a mouse autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposons class, which could offer unique chromatin compartments for the specific regulation of genes or the silencing of transposons. mapping of H3K27me3 histone modification in one MEF cell line (MEFF)
2008-12-22 | E-GEOD-12721 | biostudies-arrayexpress
Project description:Nuclear compartmentalization appears to play an important role in regulating metazoan genes. While studies on immunoglobulin (Ig) and other loci have correlated positioning at the nuclear lamina with gene repression, the functional consequences of this compartmentalization remain untested. We devised an approach for inducible tethering of genes to the inner nuclear membrane (INM) and demonstrate with 3D DNA-ImmunoFISH, repositioning of chromosomal regions to the nuclear lamina. Relocalization requires mitotic nuclear envelope breakdown and reformation. Tethering leads to the accumulation of lamin and INM proteins but not to association with pericentromeric heterochromatin or nuclear pore complexes. Recruitment of genes to the INM can result in their transcriptional repression. Using DamID we show that as is the case for our model system, inactive Ig loci at the nuclear periphery are contacted by INM and lamina components. We propose that such molecular interactions are used to compartmentalize and limit the accessibility of Ig loci. Experiment Overall Design: We used microarray to analyze the transcription status of genomic regions are inducibly tethered to the INM
2008-06-11 | E-GEOD-10176 | biostudies-arrayexpress
Project description:The majority of our genome is composed of repeated DNA sequences, which assemble into heterochromatin, a highly compacted structure that constrains their mutational potential. How heterochromatin forms during development and how its structure is maintained is not fully understood. Here, we show that mouse heterochromatin phase separates after fertilization, during the earliest stages of mammalian embryogenesis. Using high resolution, quantitative imaging and molecular biology approaches we show that pericentromeric heterochromatin displays liquid-like properties at the 2-cell stage, but it transitions into a more solid-like or gel-like state at the 4-cell stage, when chromocenters mature and heterochromatin becomes silent. Disrupting the condensates results in altered transcript levels of pericentromeric heterochromatin, suggesting a functional role for phase separation in heterochromatin function. Thus, our work shows that mouse heterochromatin forms membrane-less compartments with biophysical properties that change during development and provides new insights into the self-organization of chromatin domains during mammalian embryogenesis.
2023-08-23 | GSE211872 | GEO
Project description:Genome wide chromatin maps have shown that spreading repressive histone modifications such as H3K9me3 and H4K20me3 are present on pericentromeric and telomeric repeats and on the inactive X chromosome where H3K27me3 or H3K9me3 alternately modify megabasepair sized domains. However, only a few regions along an autosome of which Homeobox gene clusters are notable examples, have been shown to display spreading of repressive histone modifications. Here we present a ChIP-Chip map of repressive and active histone modifications along mouse Chr.17 in embryonic, fibroblast cells. Our results show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types and their flanking intergenic regions, indicating a negative correlation between H3K27me3 and transcription. However, non-transcribed gene-poor regions also lacked H3K27me3. We therefore performed a low resolution analysis of whole mouse Chr.17 which revealed that H3K27me3 specifically marks megabasepair sized domains that are enriched for genes, SINEs and active histone modifications. These genic H3K27me3 domains alternate with similar sized gene-poor domains that are deficient in active histone modifications, but enriched for LINE and LTR transposons as well as H3K9me3 and H4K20me3. Thus, a mouse autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposons class, which could offer unique chromatin compartments for the specific regulation of genes or the silencing of transposons. Keywords: RNA-chip, chromosome 17 wide expression mapping mouse chromosome 17 wide expression mapping of transcribed genes by hybridization of ds cDNA in two independent MEF cell lines
2008-11-23 | E-GEOD-11337 | biostudies-arrayexpress
Project description:Genome wide chromatin maps have shown that spreading repressive histone modifications such as H3K9me3 and H4K20me3 are present on pericentromeric and telomeric repeats and on the inactive X chromosome where H3K27me3 or H3K9me3 alternately modify megabasepair sized domains. However, only a few regions along an autosome of which Homeobox gene clusters are notable examples, have been shown to display spreading of repressive histone modifications. Here we present a ChIP-Chip map of repressive and active histone modifications along mouse Chr.17 in embryonic, fibroblast cells. Our results show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types and their flanking intergenic regions, indicating a negative correlation between H3K27me3 and transcription. However, non-transcribed gene-poor regions also lacked H3K27me3. We therefore performed a low resolution analysis of whole mouse Chr.17 which revealed that H3K27me3 specifically marks megabasepair sized domains that are enriched for genes, SINEs and active histone modifications. These genic H3K27me3 domains alternate with similar sized gene-poor domains that are deficient in active histone modifications, but enriched for LINE and LTR transposons as well as H3K9me3 and H4K20me3. Thus, a mouse autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposons class, which could offer unique chromatin compartments for the specific regulation of genes or the silencing of transposons. Keywords: Chip-chip, chromosome 17 wide unbiased mapping unbiased mapping of several histone modifications on chromosome 17 in two independent MEF cell lines
2008-11-23 | E-GEOD-11335 | biostudies-arrayexpress