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HMGA1 causes a global shift in chromatin architecture linked to transcriptional changes [RNA-Seq]

ABSTRACT: High Mobility Group A1 (HMGA1) is an architectural chromatin-binding protein that regulates gene expression in various biological contexts, including differentiation and cancer. While previous studies show that HMGA1 acts by binding specific gene promoters or by contributing to the enhanceosome, its global effect on transcription remains unclear. HMGA1 is also critical for the formation of senescence-associated heterochromatic foci (SAHF) in oncogene-induced senescence (OIS), a stable form of cell cycle arrest with a pro-inflammatory phenotype. This link between the two roles of HMGA1, gene regulation and chromatin organisation, has not been fully explained. Here, we used graph theory and data integration from high-throughput assays to investigate how HMGA1 binding impacts the chromatin interactions network. Our results demonstrate that HMGA1 profoundly remodels the global chromatin network during OIS and contributes to stronger compartmentalization. This remodelling goes beyond SAHF, leading to substantial gene repositioning and differential gene expression, highlighting a novel role for HMGA1 in altering chromatin environments. The HMGA1 effects of gene expression go beyond senescence and appear to be relevant in other contexts, such as lung cancer.

ORGANISM(S): Homo sapiens

PROVIDER: GSE245801 | GEO | 2024/07/08

REPOSITORIES: GEO

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HMGA1 causes a global shift in chromatin architecture linked to transcriptional changes [Hi-C]

Project description:High Mobility Group A1 (HMGA1) is an architectural chromatin-binding protein that regulates gene expression in various biological contexts, including differentiation and cancer. While previous studies show that HMGA1 acts by binding specific gene promoters or by contributing to the enhanceosome, its global effect on transcription remains unclear. HMGA1 is also critical for the formation of senescence-associated heterochromatic foci (SAHF) in oncogene-induced senescence (OIS), a stable form of cell cycle arrest with a pro-inflammatory phenotype. This link between the two roles of HMGA1, gene regulation and chromatin organisation, has not been fully explained. Here, we used graph theory and data integration from high-throughput assays to investigate how HMGA1 binding impacts the chromatin interactions network. Our results demonstrate that HMGA1 profoundly remodels the global chromatin network during OIS and contributes to stronger compartmentalization. This remodelling goes beyond SAHF, leading to substantial gene repositioning and differential gene expression, highlighting a novel role for HMGA1 in altering chromatin environments. The HMGA1 effects of gene expression go beyond senescence and appear to be relevant in other contexts, such as lung cancer.

2024-07-08 | GSE245804 | GEO

HMGA1 causes a global shift in chromatin architecture linked to transcriptional changes [ChIP-Seq]

2024-07-08 | GSE245802 | GEO

HMGA1 causes a global shift in chromatin architecture linked to transcriptional changes [scRNA-Seq]

2024-07-08 | GSE245807 | GEO

DNMT1 drives 4D genome rewiring during oncogene induced senescence

Project description:While, transcriptional and epigenetic changes associated senescence processes are well studied, the 3D chromatin changes associated with it remains elusive. In this study, we have generated genome wide chromatin interaction maps (Hi-C), epigenetic (ChIP-Seq), replication-timing and gene expression (RNA-Seq) profiles from replication induced (RS) and oncogene induced (OIS) senescent cells. As senescence associated heterochromatin foci (SAHFs) differentiates both RS and OIS nuclei, we identified the regions that constitute SAHFs and called them Senescence Associated Heterochromatin Domains (SAHDs). Further, screening of candidate factors for SAHF induction allowed us to identify DNMT1 as a novel component that induces SAHFs by stimulation of HMGA2 expression. DNMT1 depletion does not reverse the senescence process, however, instead, depleted cells transition to a 3D genome conformation akin to that of cells in replicative senescence, suggesting that acute senescence induction (OIS) involves SAHF formation in addition to the RS-dependent 3D genome rewiring.

2020-03-27 | GSE130306 | GEO

Hypoxia increases the methylated histones to prevent histone clipping and redistribution of heterochromatin during Raf-induced senescence.

Project description:Hypoxia increases histone methylation by inhibiting O2- and a-ketoglutarate-dependent histone lysine demethylases (KDMs). This study is the first to demonstrate how the hypoxic increment of methylated histones cross-talks with other epigenetic changes, such as histone clipping, and heterochromatin redistribution (senescence-associated heterochromatin foci, SAHF) found during oncogene-induced senescence (OIS). Raf activation in primary human fibroblasts IMR90 increased cathepsin L (CTSL)-mediated clipping of histone 3 (H3), H2B and H4 at H3 A21/T22, H2B T19/K20, and H4 G11/K12, respectively. Hypoxia protected H3 from CTSL by increasing histone methylation, especially at H3K23me3 without reducing the activity of CTSL. The maintenance of methylated histones is sufficient for protecting histones from CTSL, not sufficient but necessary for inhibiting SAHFs. Expression of cleaved H3 induces senescence even under hypoxia, suggesting that hypoxia disrupts this positive feedback loop of OIS by increasing histone methylation. Thus, hypoxia protects histones and chromatin from dramatic epigenetic changes by increasing histone methylation. These observations suggest that the OIS process increases the accessibility of chromatin, which hypoxic conditions inhibited.

2024-01-22 | GSE234895 | GEO

Massive reshaping of genome - nuclear lamina interactions during oncogene induced senescence (RNA-seq)

Project description:Cellular senescence is a mechanism that virtually irreversibly suppresses the proliferative capacity of cells in response to various stress signals. This includes the expression of activated oncogenes, which cause Oncogene-Induced Senescence (OIS). A body of evidence points to the involvement of chromatin reorganization, including the formation of senescence-associated heterochromatic foci (SAHF). The nuclear lamina (NL) is an important contributor to genome organization and has been involved in cellular senescence and organismal aging. It interacts with multiple regions of the genome called lamina-associated domains (LADs). Some LADs are cell type-specific, while others are conserved between cell types and are referred to as constitutive LADs. Here, we used DamID to investigate the changes in genome-NL interactions in a model of OIS triggered by the expression of the BRAFV600E oncogene. Results. We found that OIS cells lose most of their constitutive LADs (cLADS), suggesting the loss of a specific mechanism that targets cLADs to the NL. In addition, multiple genes relocated to the NL. Unexpectedly, they were not repressed, implying the abrogation of the repressive activity of the NL during OIS. Finally, OIS cells displayed an increased association of telomeres with the NL. Conclusions. Our study reveals that senescent cells acquire a new type of LAD organization and suggest the existence of as yet unknown mechanisms that tether cLADs to the NL and repress gene expression at the NL.

2017-08-17 | GSE75643 | GEO

Massive reshaping of genome - nuclear lamina interactions during oncogene induced senescence (DamID-seq)

Project description:Background. Cellular senescence is a mechanism that virtually irreversibly suppresses the proliferative capacity of cells in response to various stress signals. This includes the expression of activated oncogenes, which cause Oncogene-Induced Senescence (OIS). A body of evidence points to the involvement of chromatin reorganization, including the formation of senescence-associated heterochromatic foci (SAHF). The nuclear lamina (NL) is an important contributor to genome organization and has been involved in cellular senescence and organismal aging. It interacts with multiple regions of the genome called lamina-associated domains (LADs). Some LADs are cell type-specific, while others are conserved between cell types and are referred to as constitutive LADs. Here, we used DamID to investigate the changes in genome-NL interactions in a model of OIS triggered by the expression of the BRAFV600E oncogene. Results. We found that OIS cells lose most of their constitutive LADs (cLADS), suggesting the loss of a specific mechanism that targets cLADs to the NL. In addition, multiple genes relocated to the NL. Unexpectedly, they were not repressed, implying the abrogation of the repressive activity of the NL during OIS. Finally, OIS cells displayed an increased association of telomeres with the NL. Conclusions. Our study reveals that senescent cells acquire a new type of LAD organization and suggest the existence of as yet unknown mechanisms that tether cLADs to the NL and repress gene expression at the NL.

2017-08-17 | GSE76594 | GEO

Massive reshaping of genome - nuclear lamina interactions during oncogene induced senescence (genome tiling)

2017-08-17 | GSE76646 | GEO

Involvement of Condensin in Cellular Senescence through Gene Regulation and Compartmental Reorganization

Project description:Cellular senescence is a state of stable cell growth arrest induced by various stimuli such as oncogene expression and telomere shortening, referred to as oncogene-induced senescence (OIS) and replicative senescence (RS), respectively. Senescence is accompanied not only by global transcriptional alterations but also by 3D genome reorganization. Here we demonstrate that the human condensin II complex participates in cellular senescence via gene regulation and reorganization of euchromatic A and heterochromatic B chromatin compartments. OIS and RS are accompanied by A-to-B and B-to-A compartmental transitions, the latter of which occur more frequently and account for 15% of the human genome. Mechanistically, condensin is enriched at A compartments, especially at gene promoters and typical/super enhancers, and implicated in the B-to-A transitions. Genes present at B-to-A-switching regions tend to be up-regulated. The full activation of senescence genes (SASP genes and p53 targets) requires condensin; its depletion impairs senescence markers such as the activity of senescence-associated beta-galactosidase (SA-beta-gal) and senescence-associated heterochromatic foci (SAHF). This study describes that condensin reinforces euchromatic A compartments and is required for optimal expression of senescence genes, thereby contributing to the establishment and maintenance of the senescent state.

2019-11-06 | GSE118494 | GEO

Redistribution of the Lamin B1 genomic binding profile affects spatial rearrangement of heterochromatic domains and gene expression during senescence

Project description:Senescence is a stress responsive form of stable cell cycle exit. Senescent cells have a distinct gene expression profile, which is often accompanied by the spatial redistribution of heterochromatin into senescence-associated heterochromatic foci (SAHFs). Studying a key component of the nuclear lamina, lamin B1 (LMNB1), we report dynamic alterations in its genomic profile and their implications for SAHF formation and gene regulation during senescence. Genome-wide mapping reveals that LMNB1 is depleted during senescence, preferentially from the central regions of lamina-associated domains (LADs), which are enriched for H3K9me3. LMNB1 knockdown facilitates the spatial relocalization of perinuclear H3K9me3, thus promoting SAHF formation, which is inhibited by ectopic LMNB1 expression. Furthermore, despite the global reduction in LMNB1 protein levels, LMNB1 binding increases during senescence in a small subset of gene-rich regions where H3K27me3 also increases and gene expression becomes repressed. These results suggest that LMNB1 may contribute to senescence in at least two ways due to its uneven genomewide redistribution: firstly through the spatial re-organization of chromatin and, secondly, through gene repression. ChIP-seq for Lamin B1 in Growing and Ras Induced Senescence

2013-08-22 | E-GEOD-49341 | biostudies-arrayexpress

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