Saccharomyces cerevisiae
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PROVIDER: PRJNA119971 | ENA |
REPOSITORIES: ENA
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Project description:In Saccharomyces cerevisiae, Elevated Levels of Aneuploidy and Chromosome Rearrangements are Separable Genome Instability Events Controlled by the Tel1 and Mec1 Kinases Cancer cells often have elevated frequencies of chromosomal aberrations, and it is likely that loss of genome stability is one driving force behind tumorigenesis. Deficiencies in DNA replication, DNA repair, or cell cycle checkpoints can all contribute to increased rates of chromosomal duplications, deletions and translocations. The Saccharomyces cerevisiae proteins Tel1 and Mec1 (homologues of the human ATM and ATR proteins, respectively) are known to participate in the DNA damage response, replication checkpoint, and telomere maintenance pathways and are critical to maintain genome stability. In the absence of induced DNA damage, tel1 mec1 diploid yeast strains exhibit extremely high rates of chromosome aneuploidy. There is a significant bias towards trisomy of chromosomes II, VIII, X, and XII, whereas the smallest chromosomes I and VI are commonly monosomic. tel1 mec1 strains also demonstrate elevated levels of chromosome rearrangements, including translocations as well as interstitial duplications and deletions. Restoring wild-type telomere length with the Cdc13-Est2 fusion protein substantially reduces the amount of chromosome rearrangements in tel1 mec1 strains. This result suggests that most of the rearrangements are initiated by telomere-telomere fusions. However, the telomere defects associated with tel1 mec1 strains do not cause the high rate of aneuploidy, as restoring proper telomere function does not prevent cells from becoming aneuploid. Our data demonstrate that the same mutant genotype can produce both high levels of chromosome rearrangements and high levels of aneuploidy, and these two types of events occur through separate mechanisms.
2009-09-03 | GSE17903 | GEO
Project description:Aneuploidy and epigenetic alterations have long been associated with carcinogenesis, but it was unknown whether aneuploidy could disrupt the epigenetic states required for cellular differentiation. In this study, we found that ~3% of random aneuploid karyotypes in yeast disrupt the stable inheritance of silenced chromatin during cell proliferation. Karyotype analysis revealed that this phenotype was significantly correlated with gains of chromosomes III and X. Chromosome X disomy alone was sufficient to disrupt chromatin silencing and yeast mating-type identity as indicated by a lack of growth response to pheromone. The silencing defect was not limited to the cryptic mating type loci but was associated with global changes in histone modifications and chromatin localization of Sir2 histone deacetylase. The chromatin-silencing defect of disome X can be partially recapitulated by increasing the copy number of several genes on chromosome X. These results suggest that aneuploidy can directly cause epigenetic instability and disrupt cellular differentiation.
2017-09-12 | GSE98435 | GEO
Project description:Aneuploidy and epigenetic alterations have long been associated with carcinogenesis, but it was unknown whether aneuploidy could disrupt the epigenetic states required for cellular differentiation. In this study, we found that ~3% of random aneuploid karyotypes in yeast disrupt the stable inheritance of silenced chromatin during cell proliferation. Karyotype analysis revealed that this phenotype was significantly correlated with gains of chromosomes III and X. Chromosome X disomy alone was sufficient to disrupt chromatin silencing and yeast mating-type identity as indicated by a lack of growth response to pheromone. The silencing defect was not limited to the cryptic mating type loci but was associated with global changes in histone modifications and chromatin localization of Sir2 histone deacetylase. The chromatin-silencing defect of disome X can be partially recapitulated by increasing the copy number of several genes on chromosome X. These results suggest that aneuploidy can directly cause epigenetic instability and disrupt cellular differentiation.
2017-09-12 | GSE98282 | GEO
Project description:Oxidative DNA damage is likely to be involved in the etiology of cancer and is thought to accelerate tumorigenesis via increased mutation rates. However, the majority of malignant cells acquire a specific type of genomic instability characterized by large-scale genomic rearrangements, defined as chromosomal instability (CIN). The molecular mechanisms underlying CIN are largely unknown. We utilized Saccharomyces cerevisiae as a model system to delineate the relationship between genotoxic stress and CIN. It was found that elevated levels of chronic, unrepaired oxidative DNA damage cause chromosomal aberrations at remarkably high frequencies under both selective and non-selective growth conditions. In this system, exceeding the cellular capacity to appropriately manage oxidative DNA damage results in a “gain of CIN” phenotype and leads to profound karyotypic diversification. These results illustrate a novel mechanism for genome destabilization, which is likely to be relevant to human carcinogenesis. Keywords: CGH-array
2008-02-10 | GSE10152 | GEO
Project description:Aneuploidy and aging are correlated; however, a causal link between these two phenomena has remained elusive. Here we show that yeast disomic for a single native yeast chromosome generally have a decreased replicative lifespan. In addition, the extent of this lifespan deficit correlates with the size of the extra chromosome. We identified a mutation in BUL1 that rescues both the lifespan deficit and a protein trafficking defect in yeast disomic for chromosome 5. Bul1 is an E4 ubiquitin ligase adaptor involved in a protein quality-control pathway that targets membrane proteins for endocytosis and destruction in the lysosomal vacuole thereby maintaining protein homeostasis. Concurrent suppression of the aging and trafficking phenotypes suggests that disrupted membrane protein homeostasis in aneuploid yeast may contribute to their accelerated aging. The data reported here demonstrate that aneuploidy can impair protein homeostasis, shorten lifespan, and may contribute to age-associated phenotypes.
2015-12-04 | GSE75623 | GEO
Project description:Genomic instability is a common feature found in cancer cells. Accordingly, many tumor suppressor genes identified in familiar cancer syndromes are involved in the maintenance of the stability of the genome during every cell division, and are commonly referred to as caretakers. Inactivating mutations and epigenetic silencing of caretakers are thought to be the most important mechanism that explains cancer-related genome instability. However, little is known of whether transient inactivation of caretaker proteins could trigger genome instability and, if so, what types of instability would occur. In this work, we show that a brief and reversible inactivation, during just one cell cycle, of the key phosphatase Cdc14 in the model organism Saccharomyces cerevisiae is enough to result in diploid cells with multiple gross chromosomal rearrangements and changes in ploidy. Interestingly, we observed that such transient inactivation yields a characteristic fingerprint whereby trisomies are often found in small-sized chromosomes and gross chromosome rearrangements, often associated with concomitant loss of heterozygosity (LOH), are mainly detected on the rDNA-bearing chromosome XII. Taking into account the key role of Cdc14 in preventing anaphase bridges, resetting replication origins and controlling spindle dynamics in a well-defined window within anaphase, we speculate that its transient inactivation causes cells to go through a single mitotic catastrophe with irreversible consequences for the genome stability of the progeny.
2015-05-05 | GSE68530 | GEO
Project description:Aneuploidy and aging are correlated; however, a causal link between these two phenomena has remained elusive. Here we show that yeast disomic for a single native yeast chromosome generally have a decreased replicative lifespan. In addition, the extent of this lifespan deficit correlates with the size of the extra chromosome. We identified a mutation in BUL1 that rescues both the lifespan deficit and a protein trafficking defect in yeast disomic for chromosome 5. Bul1 is an E4 ubiquitin ligase adaptor involved in a protein quality-control pathway that targets membrane proteins for endocytosis and destruction in the lysosomal vacuole thereby maintaining protein homeostasis. Concurrent suppression of the aging and trafficking phenotypes suggests that disrupted membrane protein homeostasis in aneuploid yeast may contribute to their accelerated aging. The data reported here demonstrate that aneuploidy can impair protein homeostasis, shorten lifespan, and may contribute to age-associated phenotypes. These are all CGH arrays comparing DNA content between the indicated strain of interest and a wt control.
2015-12-04 | E-GEOD-75623 | biostudies-arrayexpress
Project description:Loss of the SUMO Protease Ulp2 Triggers a Specific Multi-Chromosome Aneuploidy
| PRJNA338670 | ENA
Project description:Genomic instability is a common feature found in cancer cells. Accordingly, many tumor suppressor genes identified in familiar cancer syndromes are involved in the maintenance of the stability of the genome during every cell division, and are commonly referred to as caretakers. Inactivating mutations and epigenetic silencing of caretakers are thought to be the most important mechanism that explains cancer-related genome instability. However, little is known of whether transient inactivation of caretaker proteins could trigger genome instability and, if so, what types of instability would occur. In this work, we show that a brief and reversible inactivation, during just one cell cycle, of the key phosphatase Cdc14 in the model organism Saccharomyces cerevisiae is enough to result in diploid cells with multiple gross chromosomal rearrangements and changes in ploidy. Interestingly, we observed that such transient inactivation yields a characteristic fingerprint whereby trisomies are often found in small-sized chromosomes and gross chromosome rearrangements, often associated with concomitant loss of heterozygosity (LOH), are mainly detected on the rDNA-bearing chromosome XII. Taking into account the key role of Cdc14 in preventing anaphase bridges, resetting replication origins and controlling spindle dynamics in a well-defined window within anaphase, we speculate that its transient inactivation causes cells to go through a single mitotic catastrophe with irreversible consequences for the genome stability of the progeny. The details of these experiments are in press in Genetics (Oliver Quevedo, Cristina Ramos-Pérez, Thomas D. Petes, and Félix Machín) but will be described briefly below. The diploid S. cerevisiae strain FM1468 is homozygous for a temperature-sensitive allele of CDC14 which encodes a phosphatase that is important in regulating the cell cycle. The strain was constructed by mating cdc14-1 derivatives of two sequence-diverged haploids, one isogenic with W303-1A (JSC12) and one isogenic with YJM789. The resulting diploid is heterozygous for about 55,000 SNPs (St. Charles, J. and Petes, T. (2013) PLoS Genetics 9: e1003434; PMID 23593029). In addition, the strain is homozygous for the ade2-1 ochre mutation and heterozygous for an insertion of SUP4-o, a gene encoded a tRNA ochre suppressor. The SUP4-o gene is located near the right telomere of chromosome IV and is inserted on the YJM789-derived homolog. The FM1468 strain forms pink colonies because a single copy of SUP4-o partially suppresses the red colony phenotype associated with the ade2 mutation. In the wild-type genetic background, a mitotic crossover between SUP4-o and the centromere of IV produces a red/white sectored colony with the red sector containing no copies of SUP4-o and the white sector containing two copies of SUP4-o (St. Charles and Petes, 2013). To map the position of the crossover and to examine recombination events resulting in loss of heterozygosity (LOH) throughout the genome, we used SNP-specific microarrays (St. Charles et al., 2012; Genetics 190: 1267-1284; PMID 22267500). These arrays contained about 50,000 oligonucleotides, allowing us to monitor LOH at about 13,000 positions in the genome. Each of these single-nucleotide polymorphism (SNP) was represented by four 25-base nucleotides, two for the Watson and Crick strands of the YJM789-derived SNP and two for the Watson and Crick strands of the W303-1A-derived SNP. The sequences and locations of each of these oligonucleotides has been published (St. Charles et al., 2012). As described below, by measuring the level of hybridization to these oligonucleotides, we identified the location of LOH events throughout the genome in FM1468. It should also be noted that the microarrays detect changes in chromosome number in addition to detecting LOH events. A total of 13 sectored colonies were examined. Each colony was given a number and letter indicate the sectors. For example, 1A and 1B are different sectors of one FM1468 colony. The key to the color of these colonies is: 1A (white), 1B (pink); 2A (pink), 2B (red); 3A (white), 3B (pink); 4A (white), 4B (pink); 5A (white), 5B (red); 6A (white), 6B (pink); 7A (white), 7B (pink); 8A (pink), 8B (red); 9A (white), 9B (pink); 10A (white), 10B (pink), 10C (red); 11A (white), 11B (pink), 11C (red); 12A (white), 12B (red); 13A (white), 13B (red). Note that colonies 10 and 11 were tri-colored colonies, and microarrays were done on all three sectors. In summary, microarry analysis was done on 28 sectors derived from 13 colonies.
2015-05-05 | E-GEOD-68530 | biostudies-arrayexpress
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