Chromatin de-condensation by switching substrate elasticity
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ABSTRACT:
PROVIDER: PRJNA415803 | ENA |
REPOSITORIES: ENA
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Project description:Mechanical properties of the cellular environment are known to influence cell fate. Chromatin de-condensation appears as an early event in cell reprogramming. Whereas the ratio of euchromatin versus heterochromatin can be increased chemically, we report herein for the first time that the ratio can also be increased by purely changing the mechanical properties of the microenvironment by successive 24?h-contact of the cells on a soft substrate alternated with relocation and growth for 7 days on a hard substrate. An initial contact with soft substrate caused massive SW480 cancer cell death by necrosis, whereas approximately 7% of the cells did survived exhibiting a high level of condensed chromatin (21% heterochromatin). However, four consecutive hard/soft cycles elicited a strong chromatin de-condensation (6% heterochromatin) correlating with an increase of cellular survival (approximately 90%). Furthermore, cell survival appeared to be reversible, indicative of an adaptive process rather than an irreversible gene mutation(s). This adaptation process is associated with modifications in gene expression patterns. A completely new approach for chromatin de-condensation, based only on mechanical properties of the microenvironment, without any drug mediation is presented.
| S-EPMC6107547 | biostudies-literature
Project description:The mortality in cancer is mostly related to the development of metastases that colonize and comprise the function of vital organs. During the process of dissemination to form metastases, tumor cells face changing environments. Although the consequences of the changes in chemical environment have widely been investigated, much less is known about the effects of the physical changes. We have developed a culture model in which human colon cancer cells have been recurrently grown on soft substrates versus standard rigid substrates. The soft substrates induce several phenotypic changes like the increase of cell motility and the remodeling of chromatin structure. The aim was to investigate, by RNAseq, the changes in global gene expression induced in cells grown on soft versus rigid substrates.
2018-08-22 | GSE106166 | GEO
Project description:The packaging of DNA into chromatin and its compaction within cells renders the underlying DNA template un-accessible for processes like transcription, replication and repair. Active mechanisms as chromatin modifying activities or the association with non-coding RNAs can de-condense chromatin, rendering it accessible for the DNA dependent processes. High mobility group proteins (HMG) are small architectural chromatin proteins that were shown to contribute to the regulation of chromatin accessibility and condensation. Here we show that HMGN5, a member of the HMGN family is capable to de-compact chromatin and to activate gene expression. We identified and characterized a novel RNA binding domain within HMGN5 that overlaps with its nucleosome binding domain (NBD). HMGN5 binds exclusively to nucleosomes or RNA, suggesting a switching mechanism and different functionalities depending on its binding partner. For this we show that HMGN5 is bound to regulatory regions of the genes that it tends to activate and also is found on the primary transcript of these genes. The results suggest that HMGN5 is switching from the chromatin binding to the RNA binding state after gene activation, potentially improving RNA synthesis. Furthermore, HMGN5 co-localizes and directly interacts with CTCF, suggesting a cooperative role of both proteins in organizing higher order structures of chromatin and active chromatin domains.
2024-05-08 | GSE166103 | GEO
Project description:Escherichia coli was evolved under growth conditions in which the carbon substrate alternated between glucose and either glycerol, xylose, or acetate with every tube of growth. Controls were also evolved to each substrate individually, without switching.
2017-04-19 | GSE97944 | GEO
Project description:Histone variants play crucial roles in gene expression, genome integrity and chromosome segregation. However, to what extent histone variants control chromatin architecture remains largely unknown. Here, we show that the previously uncharacterized histone variant H2A.W plays a crucial role in condensation of heterochromatin. Genome-wide profiling of all four types of H2A variants in Arabidopsis shows that H2A.W specifically associates with heterochromatin. H2A.W recruitment is independent of heterochromatic marks H3K9me2 and DNA methylation. Genetic interactions show that H2A.W acts in synergy with CMT3 mediated methylation to maintain genome integrity. In vitro, H2A.W enhances chromatin condensation through a higher propensity to make fiber-to-fiber interactions via its conserved C-terminal motif. In vivo, elimination of H2A.W causes decondensation of heterochromatin and conversely, ectopic expression of H2A.W promotes heterochromatin condensation. These results demonstrate that H2A.W plays critical roles in heterochromatin by promoting higher order chromatin condensation. Since similar H2A.W C-terminal motifs are present in other variant found in mammals and other organisms our findings impact our understanding of heterochromatin condensation in a wide variety of eukaryotic organisms. Two mRNA-seq samples, two bisulfite-seq samples, six ChIP-seq samples.
2014-07-05 | E-GEOD-50942 | biostudies-arrayexpress
Project description:Quiescence is a stress-resistant state in which cells reversibly exit the mitotic cell cycle and suspend most cellular processes. Quiescence is essential for stem cell maintenance and its misregulation is implicated in tumor formation. One of the conserved hallmarks of quiescent cells, from Saccharomyces cerevisiae to humans, is highly condensed chromatin. Here, we use Micro-C XL to map chromatin contacts at single-nucleosome resolution genome-wide to elucidate mechanisms and functions of condensed chromatin in quiescent S. cerevisiae cells. We describe previously uncharacterized chromatin domains on the order of 10-60 kilobases that in quiescent cells are formed by condensin-mediated chromatin loops. Conditional depletion of condensin prevents chromatin condensation during quiescence entry and leads to widespread transcriptional de-repression. We further demonstrate that condensin-dependent chromatin compaction is conserved in quiescent human fibroblasts. We propose that condensin-dependent condensation of chromatin represses transcription throughout the quiescent cell genome.
2018-12-27 | GSE114566 | GEO
Project description:HMGN5 is a member of the HMGN family that de-compacts chromatin and regulates gene expression. Chromatin-associated RNAs are known to play a major role in controlling gene expression and chromatin architecture. We recently showed that RNA is required to open chromatin structure in Drosophila. A potential involvement of RNA in the HMGN5-dependent opening of chromatin has not been studied so far. Here we revealed that HMGN5 has a novel and specific RNA binding activity, which is extended to the HMGN family. HMGN5 is associated preferentially with active regulatory regions and binds co-transcriptionally to the nascent RNA. Additionally, we showed that HMGN5 co-localizes and interacts with CTCF, which suggests a cooperative role of both proteins in organizing higher order structures of chromatin. We showed that HMGN5 forms mutually exclusive complexes with chromatin and RNA in vitro, altogether suggesting a dual role for HMGN5 in gene regulation, switching from nucleosome to RNA binding during gene activation.
2024-05-08 | GSE166101 | GEO
Project description:HMGN5 is a member of the HMGN family that de-compacts chromatin and regulates gene expression. Chromatin-associated RNAs are known to play a major role in controlling gene expression and chromatin architecture. We recently showed that RNA is required to open chromatin structure in Drosophila. A potential involvement of RNA in the HMGN5-dependent opening of chromatin has not been studied so far. Here we revealed that HMGN5 has a novel and specific RNA binding activity, which is extended to the HMGN family. HMGN5 is associated preferentially with active regulatory regions and binds co-transcriptionally to the nascent RNA. Additionally, we showed that HMGN5 co-localizes and interacts with CTCF, which suggests a cooperative role of both proteins in organizing higher order structures of chromatin. We showed that HMGN5 forms mutually exclusive complexes with chromatin and RNA in vitro, altogether suggesting a dual role for HMGN5 in gene regulation, switching from nucleosome to RNA binding during gene activation.
2024-05-08 | GSE166098 | GEO
Project description:HMGN5 is a member of the HMGN family that de-compacts chromatin and regulates gene expression. Chromatin-associated RNAs are known to play a major role in controlling gene expression and chromatin architecture. We recently showed that RNA is required to open chromatin structure in Drosophila. A potential involvement of RNA in the HMGN5-dependent opening of chromatin has not been studied so far. Here we revealed that HMGN5 has a novel and specific RNA binding activity, which is extended to the HMGN family. HMGN5 is associated preferentially with active regulatory regions and binds co-transcriptionally to the nascent RNA. Additionally, we showed that HMGN5 co-localizes and interacts with CTCF, which suggests a cooperative role of both proteins in organizing higher order structures of chromatin. We showed that HMGN5 forms mutually exclusive complexes with chromatin and RNA in vitro, altogether suggesting a dual role for HMGN5 in gene regulation, switching from nucleosome to RNA binding during gene activation.
2024-05-08 | GSE166091 | GEO
Project description:Quiescence is a stress-resistant state in which cells reversibly exit the mitotic cell cycle and suspend most cellular processes. Quiescence is essential for stem cell maintenance and its misregulation is implicated in tumor formation. One of the conserved hallmarks of quiescent cells, from Saccharomyces cerevisiae to humans, is highly condensed chromatin. Here, we use Micro-C XL to map chromatin contacts at single-nucleosome resolution genome-wide to elucidate mechanisms and functions of condensed chromatin in quiescent S. cerevisiae cells. We describe previously uncharacterized chromatin domains on the order of 10-60 kilobases that in quiescent cells are formed by condensin-mediated chromatin loops. Conditional depletion of condensin prevents chromatin condensation during quiescence entry and leads to widespread transcriptional de-repression. We further demonstrate that condensin-dependent chromatin compaction is conserved in quiescent human fibroblasts. We propose that condensin-dependent condensation of chromatin represses transcription throughout the quiescent cell genome.
2018-12-27 | GSE120605 | GEO