Hypoxia increases the methylated histones to prevent histone clipping and redistribution of heterochromatin during Raf-induced senescence.
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE234895 | GEO | 2024/01/22
REPOSITORIES: GEO
Similar Datasets
Project description:Hypoxia in stem cell niches and inner core of solid tumors contributes to cellular senescence and differentiation inhibition. It directly increases histone methylationby inhibiting the activities of O2-and α-ketoglutarate (α-KG)-dependent histone lysine demethylases. 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, named senescence-associated heterochromatin foci (SAHF), which are found during oncogene-induced senescence (OIS). This study showed that Raf activation in primary human fibroblasts IMR90 increases mature cathepsin L (CTSL)-mediated cleavage of H3, H2B, and H4. Hypoxia prevented H3 cleavage not by inhibiting CTSL but by increasing H3K18me3 and H3K23me3 nearby cleaved site of H3. Forced expression of cleaved H3 in IMR90 cells induced senescence even under hypoxia, suggesting that hypoxia breaks this positive feedback senescence driving circle by increasing methylated histones. The decrease in methylated histones is necessary for OIS to trigger histone clipping and SAHFs, but hypoxia maintains methylated histones to prevent both. Forced reduction of methylated histones in hypoxic cells using inhibitors of methyl-transferases makes hypoxic conditions unable to prevent OIS from inducing both histone clipping and SAHFs. Reversely forced enhancement of methylated histones in normoxic cells using inhibitors of histone demethylases protected histones from clipping during OIS but failed to block SAHFs. Altogether, the maintenance of methylated histones, especially H3K23me3 and H3K18me3, is sufficient to protect histones from clipping during OIS, but not for inhibiting SAHFs, suggesting that besides inhibiting KDMs, hypoxia adopts other methods to inhibit SAHFs. These findings provide a novel mechanism by which hypoxia affects cell fate by increasing methylated histones that protect histones and chromatin from dramatic epigenetic changes.
2024-11-27 | PXD033971 | Pride
Project description:This model is described in the article:
Kinetics of histone gene expression during early development of Xenopus laevis.
Koster JG, Destrée OH and Westerhoff HV. J Theor Biol.
1988 Nov 21;135(2):139-67. PMID: 3267765
Abstract:
Using literature data for transcriptional and translational rate constants, gene copy numbers, DNA concentrations, and stability constants, we have calculated the expected concentrations of histones and histone mRNA during embryogenesis of Xenopus laevis. The results led us to conclude that: (i) for X. laevis the gene copy number of the histone genes is too low to ensure the synthesis of sufficient histones during very early development, inheritance from the oocyte of either histone protein or histone mRNA (but not necessarily both) is necessary; (ii) from the known storage of histones in the oocyte and the rates of histone synthesis determined by Adamson and Woodland (1977), there would be sufficient histones to structure the newly synthesized DNA up to gastrulation but not thereafter (these empirical rates of histone synthesis may be underestimates); (iii) on the other hand, the amount of H3 mRNA recently observed during early embryogenesis (Koster, 1987, Koster et al., 1988) could direct a higher and sufficient synthesis of H3 protein, also after gastrulation. We present a quantitative model that accounts both for the observed H3 mRNA concentration as a function of time during embryogenesis and for the synthesis of sufficient histones to structure the DNA throughout early embryogenesis. The model suggests that X. laevis exhibits a major (i.e. some 14-fold) reduction in transcription of histone genes approximately 11 hours after fertilization. This reduction could be due to a decrease in the number of transcribed histone genes, a decreased rate constant of transcription with continued transcription of all the histone genes, and/or a reduction in the time during the cell cycle in which histone mRNA synthesis takes place. Alternatively, the histone mRNA stability might decrease approximately 16-fold 11 hours after fertilization.
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2005-01-01 | MODEL5954483266 | BioModels
Project description:The proteolytic cleavage of histone tails, also termed histone clipping, has been described as a mechanism for permanent removal of post-translational modifications (PTMs) from histone proteins. Such activity has been ascribed to ensure regulatory function in key cellular processes such as differentiation, senescence and transcriptional control for which different histone-specific proteases has been described. However, all these studies were exclusively performed using cell lines cultured in vitro and no clear evidences that histone clipping is regulated in vivo has been reported. Here we show that histone H3 N-terminal tails undergo extensive cleavage in the differentiated cells of the villi fraction of the mouse intestinal epithelium. Combining biochemical methods, 3D organoids cultures and in vivo approaches, we demonstrate that intestinal H3 clipping is the result of multiple proteolytic activities. We identified Trypsins and Cathepsin L as specific H3 tail proteases active in small intestinal differentiated cells and showed that their proteolytic activity is differentially affected by the PTM pattern of histone H3 tails. Together, our findings provide in vivo evidences of H3 tail proteolysis in mammalian tissues directly linking H3 clipping to cell differentiation.
2020-12-04 | GSE160776 | GEO
Project description:The proteolytic cleavage of histone tails, also termed histone clipping, has been described as a mechanism for permanent removal of post-translational modifications (PTMs) from histone proteins. Such activity has been ascribed to ensure regulatory function in key cellular processes such as differentiation, senescence and transcriptional control for which different histone-specific proteases has been described. However, all these studies were exclusively performed using cell lines cultured in vitro and no clear evidences that histone clipping is regulated in vivo has been reported. Here we show that histone H3 N-terminal tails undergo extensive cleavage in the differentiated cells of the villi fraction of the mouse intestinal epithelium and we investigate histone PTM changes in full-length compared with clipped histone H3.
2021-01-11 | PXD022171 | Pride
Project description:Current protocols used to extract and purify histones are notoriously tedious, especially when using yeast cells. Here, we describe the use of a simple filter-aided sample preparation approach enabling histone extraction from yeast and mammalian cells using acidified ethanol, a condition that not only improves extraction but also inactivates histone-modifying enzymes. We show that our improved method preserves the integrity of histones, and prevents N-terminal clipping of H3, an artefact frequently observed in yeast cells using standard histone extraction protocols. Our method is scalable and provides efficient recovery of histones when extracts are prepared from as little as two million yeast cells. We further demonstrate the application of this approach for the analysis of histone modifications including fungal clinical isolates available in limited quantity. Altogether, this method enables the study of histones and their modifications in a faster, simpler, and more robust manner.
2023-08-10 | PXD041524 | Pride
Project description:How histone posttranslational modifications (PTMs) are inherited through cell cycle remains poorly understood. Canonical histones are made in the S phase of cell cycle. Combining mass spectrometry-based technologies and stable isotope labeling by amino acids in cell culture (SILAC), we interrogate the distributions of multiple major histone PTMs on old versus new histones in synchronized human cells. We show that histone PTMs can be grouped to three categories accordingly to their distributions. Most lysine mono-methylation and acetylation PTMs are either symmetrically distributed on old and new histones, or asymmetric on new histones. In contrast, most di- and tri-methylation PTMs are asymmetric on old histones, suggesting the inheritance of different PTMs is regulated distinctly. Intriguingly, old and new histones are distinguished in their phosphorylation status during early mitosis, in three different human cell types: Hela, 293T and human foreskin fibroblast (HFF) cells. The mitotic hallmark H3S10ph is predominantly associated with old H3 at early mitosis and become symmetric with the progression of mitosis. The same distribution pattern is found on other mitotic histone phosphorylation marks, including H3T3/T6ph, H3.1/2S28ph and H1.4S26ph, excluding S28/S31ph on the H3 variant H3.3. Although H3S10ph often associates with the neighboring K9 di- or tri-methylation, they are not required for the asymmetric distribution of S10ph on the same H3 tail. Inhibition of the kinase Aurora B does not change the distribution pattern despite significant reduction of H3S10ph levels. K9me2 abundance on the new H3 is significantly reduced after Aurora B inhibition, suggesting a crosstalk between H3S10ph and H3K9me2.
2016-06-01 | PXD003709 | Pride
Project description:Oncogene-induced senescence (OIS) and therapy-induced senescence (TIS), while tumor-suppressive, also promote procarcinogenic effects by activating the DNA damage response (DDR), which in turn induces inflammation. This inflammatory response prominently includes an array of cytokines known as the senescence-associated secretory phenotype (SASP). Previous observations link the transcription-associated methyltransferase and oncoprotein MLL1 to the DDR, leading us to investigate the role of MLL1 in SASP expression. Our findings reveal direct MLL1 epigenetic control over proproliferative cell cycle genes: MLL1 inhibition represses expression of proproliferative cell cycle regulators required for DNA replication and DDR activation, thus disabling SASP expression. Strikingly, however, these effects of MLL1 inhibition on SASP gene expression do not impair OIS and, furthermore, abolish the ability of the SASP to enhance cancer cell proliferation. More broadly, MLL1 inhibition also reduces �SASP-like� inflammatory gene expression from cancer cells in vitro and in vivo independently of senescence. Taken together, these data demonstrate that MLL1 inhibition may be a powerful and effective strategy for inducing cancerous growth arrest through the direct epigenetic regulation of proliferation-promoting genes and the avoidance of deleterious OIS- or TIS-related tumor secretomes, which can promote both drug resistance and tumor progression. This study examines the genome-wide distribution of gH2A.x and H3K4me3 by chIP-seq, using input and whole histone subunit H3 (respectively) as controls for local sonication efficiency bias. Each of the four chIPs has a single replicate each in (i) IMR90 fibroblasts transfected with a scramble control vector, (ii) the same cells subject to oncogene-induced senescence by stimulation of H-Ras V12, and (iii) in OIS cells with a shRNA targeting MLL1. Additionally, gH2A.x and input were sequenced with another replicate in control and OIS cells (both scramble control).
2016-02-23 | E-GEOD-78141 | biostudies-arrayexpress
Project description:Here we examined whether histones H3 and H4 produced using native chemical ligation reaction affect protein binding to di-nucleosomes. To test this we performed a set of affinity purification pull-downs using di-nucleosomes containing the following histones H3 and H4: 1. unmodified ligated histone H3 and recombinant wild type histone H4 (unmod. H3), 2. recombinant wild type histone H3 and ligated unmodified histone H4 (unmod. H4) 3. ligated unmodified histones H3 and H4 (unmod. H3&H4). 4. recombinant wild type histones H3 and H4 (WT) Each pull-down was performed in three replicates. Co-purified proteins were quantified using label-free MS. Note that ligated histones H3 and H4 contain T32C or I29C single amino acid substitutions, respectively, that are introduced by the native chemical ligation procedure. In addition, ligated histone H4 is N-terminally acetylated to mimic its naturally blocked N-terminus.
2023-12-12 | PXD042390 | Pride
Project description:Here we examined whether histones H3 and H4 produced using native chemical ligation reaction affect protein binding to di-nucleosomes. To test this we performed a set of affinity purification pull-downs using di-nucleosomes containing the following histones H3 and H4: 1. ligated unmodified histone H3 and recombinant wild type histone H4 (unmod. H3), 2. recombinant wild type histone H3 and ligated unmodified histone H4 (unmod. H4) 3. ligated unmodified histones H3 and H4 (unmod. H3&H4). 4. recombinant wild type histones H3 and H4 (WT) Each pull-down was performed in three replicates. Co-purified proteins were quantified using label-free MS. Note that ligated histones H3 and H4 contain T32C or I29C single amino acid substitutions, respectively, that are introduced by the native chemical ligation procedure. In addition, ligated histone H4 is N-terminally acetylated to mimic its naturally blocked N-terminus.
2023-12-10 | PXD042630 | Pride