Depletion of limiting rDNA structural complexes triggers chromosomal instability and replicative aging of Saccharomyces cerevisiae
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ABSTRACT:
PROVIDER: PRJNA480885 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR7531162_1.fastq.gz | Fastqsanger.gz | |||
| SRR7531162_2.fastq.gz | Fastqsanger.gz | |||
| SRR7531163_1.fastq.gz | Fastqsanger.gz | |||
| SRR7531163_2.fastq.gz | Fastqsanger.gz | |||
| SRR7531164_1.fastq.gz | Fastqsanger.gz |
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Project description:Sir2 is a highly conserved NAD+-dependent histone deacetylase that functions in heterochromatin formation and promotes replicative lifespan (RLS) in the budding yeast, Saccharomyces cerevisiae. Within the yeast rDNA locus, Sir2 is required for efficient cohesin recruitment and maintaining stability of the tandem array. In addition to the previously reported depletion of Sir2 in replicatively aged cells, we discovered that subunits of the Sir2 containing complexes, SIR and RENT, were depleted. Several other rDNA structural protein complexes also exhibited age-related depletion, most notably the cohesin complex. We hypothesized that mitotic chromosome instability (CIN) due to cohesin depletion could be a driver of replicative aging. ChIP assays of the residual cohesin (Mcd1-13xMyc) in moderately aged cells showed strong depletion from the rDNA and initial redistribution to the point centromeres, which was then lost in older cells. Despite the shift in cohesin distribution, sister chromatid cohesion was partially attenuated in aged cells and the frequency of chromosome loss was increased. This age-induced CIN was exacerbated in strains lacking Sir2 and its paralog, Hst1, but suppressed in strains that stabilize the rDNA array due to deletion of FOB1 or through caloric restriction (CR). Furthermore, ectopic expression of MCD1 from a doxycycline-inducible promoter was sufficient to suppress rDNA instability in aged cells and to extend RLS. Taken together we conclude that age-induced depletion of cohesin and multiple other nucleolar chromatin factors destabilize the rDNA locus, which then results in general CIN and aneuploidy that shortens RLS.
2019-03-12 | GSE117037 | GEO
Project description:Sir2 is a highly conserved NAD+-dependent histone deacetylase that functions in heterochromatin formation and promotes replicative life span (RLS) in the budding yeast, Saccharomyces cerevisiae Within the yeast rDNA locus, Sir2 is required for efficient cohesin recruitment and maintaining the stability of the tandem array. In addition to the previously reported depletion of Sir2 in replicatively aged cells, we discovered that subunits of the Sir2-containing complexes silent information regulator (SIR) and regulator of nucleolar silencing and telophase (RENT) were depleted. Several other rDNA structural protein complexes also exhibited age-related depletion, most notably the cohesin complex. We hypothesized that mitotic chromosome instability (CIN) due to cohesin depletion could be a driver of replicative aging. Chromatin immunoprecipitation assays of the residual cohesin (Mcd1-Myc) in moderately aged cells showed strong depletion from the rDNA and initial redistribution to the point centromeres, which was then lost in older cells. Despite the shift in cohesin distribution, sister chromatid cohesion was partially attenuated in aged cells and the frequency of chromosome loss was increased. This age-induced CIN was exacerbated in strains lacking Sir2 and its paralog, Hst1, but suppressed in strains that stabilize the rDNA array due to deletion of FOB1 or through caloric restriction. Furthermore, ectopic expression of MCD1 from a doxycycline-inducible promoter was sufficient to suppress rDNA instability in aged cells and to extend RLS. Taken together, we conclude that age-induced depletion of cohesin and multiple other nucleolar chromatin factors destabilize the rDNA locus, which then results in general CIN and aneuploidy that shortens RLS.
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Project description:Replicative crisis is a senescence-independent process that acts as a final barrier against oncogenic transformation by eliminating pre-cancerous cells with disrupted cell cycle checkpoints1. It functions as a potent tumour suppressor and culminates in extensive cell death. Cells rarely evade elimination and evolve towards malignancy, but the mechanisms that underlie cell death in crisis are not well understood. Here we show that macroautophagy has a dominant role in the death of fibroblasts and epithelial cells during crisis. Activation of autophagy is critical for cell death, as its suppression promoted bypass of crisis, continued proliferation and accumulation of genome instability. Telomere dysfunction specifically triggers autophagy, implicating a telomere-driven autophagy pathway that is not induced by intrachromosomal breaks. Telomeric DNA damage generates cytosolic DNA species with fragile nuclear envelopes that undergo spontaneous disruption. The cytosolic chromatin fragments activate the cGAS-STING (cyclic GMP-AMP synthase-stimulator of interferon genes) pathway and engage the autophagy machinery. Our data suggest that autophagy is an integral component of the tumour suppressive crisis mechanism and that loss of autophagy function is required for the initiation of cancer.
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Project description:In this study we perform ATAC-seq of budding yeast strains with variable copy number of the rRNA genes (rDNA CN). We aim to better understand the relationship between DNA accessibility and replicative lifespan in strains with variable rDNA CN.
2022-04-05 | GSE193598 | GEO
Project description:Aberrant cell proliferation, a hallmark of most cancers, requires the escape from intrinsic antitumour barriers. Primary among these is the DNA damage response (DDR). In both cell culture-models and in early stages of tumorigenesis in vivo, activated oncogenes induce DNA replication stress and DNA double-strand breaks (DSBs), leading to DDR activation and p53-dependent apoptosis and/or senescence. The means by which tumour initiating cells, also termed cancer stem cells (CSCs), circumvent this oncosuppressive response is unknown. Here we demonstrate that the ZEB1 transcription factor provides breast CSCs with the ability to withstand an aberrant mitogenic activity. Its forced expression in human mammary epithelial cells is sufficient to alleviate DNA replicative stress and to decrease the production of reactive oxygen species, an important contributor to DDR and oncogene-induced senescence. Consistently, human breast cancer cells with endogenous ZEB1 expression show two characteristic features: low levels of DSBs and DDR markers, reflecting mitigation of the DNA replication stress, and a low p53 mutation frequency, reflecting a weak selective pressure for inactivation. Using high-throughput sequencing analysis of controlled cellular models, we further demonstrate that ZEB1 delays the onset of structural chromosomal instability (CIN), a known consequence of replicative stress and prevents the emergence of chromosome 8p deletions and 8q amplifications, two prevalent abnormalities in high grade breast cancers. Supporting these findings, ZEB1 expression discriminates human breast tumours by their copy number alterations (CNAs) and chromosome 8 aberrations. We propose that the tumorigenic potential of CSCs relies upon their unique capacity to tolerate oncogenic stimuli through the alleviation of DNA replication stress. Immortalized human mammary epithelial cells were infected with retrovirus expressing H-RASV12 with or without a retrovirus expressing ZEB1.
2015-12-31 | E-GEOD-55989 | biostudies-arrayexpress
Project description:Chromatin remodelers are recurrently mutated in cancer. Among these, JARID1C, (KDM5C) a histone demethylase, is frequently inactivated in clear cell renal cell carcinoma (ccRCC) patients. How the genetic inactivation of JARID1C leads to cancer remains largely unknown. Here we report that JARID1C binds to broad chromatin domains characterized by the trimethylation of lysine 9 (H3K9me3), an histone mark enriched in heterochromatin. We also found that JARID1C localizes on heterochromatin, is required for heterochromatin replication, and forms a complex with established and novel players of heterochromatin assembly, such as SUV39H1 and HP1 and the CUL4 complex adaptor protein DDB1, respectively. To safeguard the genome, transcription on heterochromatin is tightly suppressed. JARID1C inactivation leads to the unrestrained expression of heterochromatic ncRNAs, that in turn trigger genomic instability. Remarkably, ccRCC patients harbouring JARID1C mutations show aberrant ncRNA expression and increased genomic rearrangements when compared with tumors endowed with other genetic lesions. Together, these data suggest that the inactivation of JARID1C in renal cancer leads to heterochromatin disruption and to aggressive, genomically rearranged ccRCCs, shedding light on a novel mechanism underlying genomic instability in sporadic cancers. We performed ChIP-sequencing for KDM5C, H3K9me3, H3K4me1 and H3K4me3 in Caki-1 untreated cells. Platform HiSeq2500.
2015-11-09 | E-GEOD-73267 | biostudies-arrayexpress
Project description:All eukaryotic cells divide a finite number of times, termed replicative aging, but the reason for this is not clear. Consistent with the decreased total histone protein levels in aged Saccharomyces cerevisiae, which is a cause of aging (1), we find that nucleosome occupancy decreases 50% across the whole genome during replicative aging by spike-in controlled MNase sequencing. Nucleosomes become fuzzier or move to sequences predicted to better accommodate histone octamers. All yeast genes are induced during aging. Genes that are repressed in young cells are most induced, accompanied by nucleosome loss from their promoters that have unique chromatin organization. Contrary to the loss of mitochondrial function during aging, mitochondrial DNA content increases and unprecedented levels of large-scale chromosomal alterations and increased retrotransposition are observed. Mnase-Seq experiments were carried out for young yeast, old yeast, and old yeast with histone over expression, 3 replicates were done for each category. RNA-Seq were carried out for the same categories of yeast cells but with 2 replicates for each. Genome-Seq were done for the young and old yeast with 2 replicates for each.
2014-02-26 | E-GEOD-47023 | biostudies-arrayexpress
Project description:All eukaryotic cells divide a finite number of times, termed replicative aging, but the reason for this is not clear. Consistent with the decreased total histone protein levels in aged Saccharomyces cerevisiae, which is a cause of aging (1), we find that nucleosome occupancy decreases 50% across the whole genome during replicative aging by spike-in controlled MNase sequencing. Nucleosomes become fuzzier or move to sequences predicted to better accommodate histone octamers. All yeast genes are induced during aging. Genes that are repressed in young cells are most induced, accompanied by nucleosome loss from their promoters that have unique chromatin organization. Contrary to the loss of mitochondrial function during aging, mitochondrial DNA content increases and unprecedented levels of large-scale chromosomal alterations and increased retrotransposition are observed.
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