Chromatin structure restricts origin utilization when quiescent cells re-enter the cell cycle
Ontology highlight
ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
PROVIDER: GSE155831 | GEO | 2020/08/07
REPOSITORIES: GEO
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Project description:Quiescence is a distinct cell cycle phase, termed G0, in which growth, transcription, translation, and replication are suppressed. Yeast cells enter G0 following glucose exhaustion but remain viable for an extended period and can re-enter the cell cycle when returned to glucose-rich medium. Quiescence is a feature of all organisms and is essential for the maintenance of stem cells and tissue renewal. Quiescence is also related to chronological lifespan (CLS) - or the capacity of post-mitotic quiescent cells to survive over time - and thus contributes to longevity. However, important questions remain to be answered regarding the mechanisms that control entry into quiescence, the maintenance of quiescence, and the re-entry of quiescent cells into the cell cycle. Histone acetylation is lost during the formation of quiescent yeast cells, and chromatin becomes highly condensed. This unique chromatin landscape plays a key role in supporting quiescence-specific transcriptional repression and has been linked to the formation and maintenance of quiescent cells. To ask if other chromatin features regulate quiescence, we conducted a comprehensive screen of histone H3 and H4 mutants. We identified several mutants that show altered quiescence entry and have characterized their chromatin phenotypes. None of these mutants retain histone acetylation, while several have altered chromatin condensation. Additionally, a screen for H3 and H4 mutants with altered chronological lifespan showed that CLS is highly correlated with quiescence entry.
2023-03-01 | GSE210305 | GEO
Project description:Background: Although quiescence—reversible cell-cycle arrest—is a key part in the life history and fate of many mammalian cell types, the mechanisms of gene regulation in quiescent cells are poorly understood. We sought to clarify the role of microRNAs as regulators of the cellular functions of quiescent human fibroblasts. Results: Using microarrays, we discovered that the expression of the majority of profiled microRNAs differed between proliferating and quiescent fibroblasts. Fibroblasts induced into quiescence by contact inhibition or serum starvation had similar microRNA profiles, indicating common changes induced by distinct quiescence signals. By analyzing the gene expression patterns of microRNA target genes with quiescence, we discovered a strong regulatory function for miR-29, which is downregulated with quiescence. Using microarrays and immunoblotting, we confirmed that miR-29 targets genes encoding collagen and other extracellular matrix proteins and that those target genes are induced in quiescence. In addition, overexpression of miR-29 resulted in more rapid cell cycle re-entry from quiescence. We also found that let-7 and miR-125 were upregulated in quiescent cells. Overexpression of either one alone resulted in slower cell cycle re-entry from quiescence, while the combination of both together slowed cell cycle re-entry even further. Conclusions: microRNAs regulate key aspects of fibroblast quiescence including the proliferative state of the cells as well as their gene expression profiles, in particular, the induction of extracellular matrix proteins in quiescent fibroblasts. microRNAs in human neonatal dermal fibroblasts in 3 cell cycle conditions (proliferating, 4 days serum starved, 7 days contact inhibited) were analyzed by one color microarray. 3 separate fibroblast cell lines from different human donors were analyzed for each condition, with two separate labeling and hybridization samples for each cell line. In total, 18 samples were hybridized to the microRNA microarray.
2012-12-05 | E-GEOD-42593 | biostudies-arrayexpress
Project description:Background: Although quiescence—reversible cell-cycle arrest—is a key part in the life history and fate of many mammalian cell types, the mechanisms of gene regulation in quiescent cells are poorly understood. We sought to clarify the role of microRNAs as regulators of the cellular functions of quiescent human fibroblasts. Results: Using microarrays, we discovered that the expression of the majority of profiled microRNAs differed between proliferating and quiescent fibroblasts. Fibroblasts induced into quiescence by contact inhibition or serum starvation had similar microRNA profiles, indicating common changes induced by distinct quiescence signals. By analyzing the gene expression patterns of microRNA target genes with quiescence, we discovered a strong regulatory function for miR-29, which is downregulated with quiescence. Using microarrays and immunoblotting, we confirmed that miR-29 targets genes encoding collagen and other extracellular matrix proteins and that those target genes are induced in quiescence. In addition, overexpression of miR-29 resulted in more rapid cell cycle re-entry from quiescence. We also found that let-7 and miR-125 were upregulated in quiescent cells. Overexpression of either one alone resulted in slower cell cycle re-entry from quiescence, while the combination of both together slowed cell cycle re-entry even further. Conclusions: microRNAs regulate key aspects of fibroblast quiescence including the proliferative state of the cells as well as their gene expression profiles, in particular, the induction of extracellular matrix proteins in quiescent fibroblasts. mRNAs were analyzed by two color microarray from three separate human neonatal dermal fibroblasts cell lines transfected either with a miR-29b mimic or a control short dsRNA. One sample was labeled and analyzed in duplicate to ensure consistency in labeling and hybridization technique.
2012-12-05 | E-GEOD-42613 | biostudies-arrayexpress
Project description:Background: Although quiescence—reversible cell-cycle arrest—is a key part in the life history and fate of many mammalian cell types, the mechanisms of gene regulation in quiescent cells are poorly understood. We sought to clarify the role of microRNAs as regulators of the cellular functions of quiescent human fibroblasts. Results: Using microarrays, we discovered that the expression of the majority of profiled microRNAs differed between proliferating and quiescent fibroblasts. Fibroblasts induced into quiescence by contact inhibition or serum starvation had similar microRNA profiles, indicating common changes induced by distinct quiescence signals. By analyzing the gene expression patterns of microRNA target genes with quiescence, we discovered a strong regulatory function for miR-29, which is downregulated with quiescence. Using microarrays and immunoblotting, we confirmed that miR-29 targets genes encoding collagen and other extracellular matrix proteins and that those target genes are induced in quiescence. In addition, overexpression of miR-29 resulted in more rapid cell cycle re-entry from quiescence. We also found that let-7 and miR-125 were upregulated in quiescent cells. Overexpression of either one alone resulted in slower cell cycle re-entry from quiescence, while the combination of both together slowed cell cycle re-entry even further. Conclusions: microRNAs regulate key aspects of fibroblast quiescence including the proliferative state of the cells as well as their gene expression profiles, in particular, the induction of extracellular matrix proteins in quiescent fibroblasts.
2012-12-05 | GSE42613 | GEO
Project description:Background: Although quiescence—reversible cell-cycle arrest—is a key part in the life history and fate of many mammalian cell types, the mechanisms of gene regulation in quiescent cells are poorly understood. We sought to clarify the role of microRNAs as regulators of the cellular functions of quiescent human fibroblasts. Results: Using microarrays, we discovered that the expression of the majority of profiled microRNAs differed between proliferating and quiescent fibroblasts. Fibroblasts induced into quiescence by contact inhibition or serum starvation had similar microRNA profiles, indicating common changes induced by distinct quiescence signals. By analyzing the gene expression patterns of microRNA target genes with quiescence, we discovered a strong regulatory function for miR-29, which is downregulated with quiescence. Using microarrays and immunoblotting, we confirmed that miR-29 targets genes encoding collagen and other extracellular matrix proteins and that those target genes are induced in quiescence. In addition, overexpression of miR-29 resulted in more rapid cell cycle re-entry from quiescence. We also found that let-7 and miR-125 were upregulated in quiescent cells. Overexpression of either one alone resulted in slower cell cycle re-entry from quiescence, while the combination of both together slowed cell cycle re-entry even further. Conclusions: microRNAs regulate key aspects of fibroblast quiescence including the proliferative state of the cells as well as their gene expression profiles, in particular, the induction of extracellular matrix proteins in quiescent fibroblasts.
2012-12-05 | GSE42593 | GEO
Project description:Quiescence (G0) is a reversible non-dividing state that facilitates cellular survival in adverse conditions. Here we demonstrate that the function of the HIRA histone chaperone complex is required for viability during nitrogen-starvation induced quiescence in Schizosaccharomyces pombe. G0 cells lacking the HIRA protein, Hip1 exhibit elevated levels of antisense ncRNAs and an increase in unrepaired DNA double strand breaks. Nitrogen-starved hip1∆ cells retain metabolic activity but, in contrast to wild type, rapidly lose the ability to resume proliferation. After a short period in G0 (1 day), hip1∆ mutants are able to resume cell growth in response to the restoration of a nitrogen source, but do not efficiently induce Start-specific gene expression and re-enter the cell cycle. However, hip1∆ cells rapidly progress to an unresponsive state and by 4 days in G0, the majority no longer initiate growth following nitrogen source restoration. Analysis using a conditional hip1 allele is consistent with these findings and indicates that HIRA is required for efficient exit from quiescence and prevents a permanent cell cycle arrest.
2023-11-13 | GSE129599 | GEO
Project description:Cellular quiescence is coupled with cellular development, tissue homeostasis, and cancer progression. Both quiescence and cell cycle re-entry are controlled by active and precise regulation of gene expression. However, the roles of long noncoding RNAs (lncRNAs) during these processes remain to be elucidated. By performing a genome-wide transcriptome analyses, we identify thousands of differentially expressed lncRNAs, including ~30 of the less-characterized class of microRNA-host-gene lncRNAs (lnc-MIRHGs), during cellular quiescence and during serum-stimulation in human diploid cells. We observe that the mature MIR222HG display serum-stimulated induction due to enhanced pre-RNA splicing. Serum-stimulated binding of the pre-mRNA splicing factor SRSF1 to a micro-exon, which partially overlaps with the primary miR-222 precursor, facilitates enhanced MIR222HG splicing. In serum-stimulated cells, SRSF1 negatively regulates the Drosha/DGCR8-catalyzed cleavage of pri-miR-222, thereby increasing the cellular pool of the mature MIR222HG. Further, loss-of-function studies indicate that the mature MIR222HG facilitates the serum-stimulated cell cycle re-entry in a microRNA-independent manner. Mechanistically, MIR222HG, along with ILF3/2 complex, forms RNA:RNA duplex with DNM3OS lncRNA, thereby promoting DNM3OS stability. The current study identifies a mechanism in which the interplay between splicing versus microprocessor complex dictates the serum-induced expression of lnc-MIRHG MIR222HG for efficient cell cycle re-entry.
2020-09-07 | PXD017585 | Pride
Project description:Parasitic protists, including Plasmodium falciparum malaria parasites, evolved sophisticated biological features to adapt and survive in e.g. mosquito vectors and mammalian hosts. The parasite’s life cycle is extraordinarily controlled, oscillating between quiescent stages (e.g. sporozoites or gametocytes) and stages of intense proliferation. The atypical mode of asexual reproduction in erythrocytes (schizogony: asynchronous nuclear division in the absence of cytokinesis), is clearly divergent from cell division in higher eukaryotes but the mechanisms that control cell cycle progression are poorly understood. Here, depletion of exogenous factors was used to induce reversible cell cycle arrest and allowed transcriptomic investigations of cell cycle control mechanisms operating in the parasite. We show that in early stages of erythrocyte infection, parasites enter a quiescent, G0-like state due to implementation of a G1 restriction point prior to G1/S transition. This quiescence is reversible, with cells making a clear decision to re-engage the proliferation machinery in response to proliferation stimuli. Cell cycle arrest is an adaptive response rather than merely prolongation of the G1 phase, as demonstrated by a distinct transcriptome. The quiescence-proliferation decision-making process in malaria parasites has hallmarks of unique regulatory principles: quiescence is associated with a deregulation of the pre-replicative complex, underlined by transcriptional control of kinases, including PfPK5 as putative functional homologue of the master mammalian cell cycle regulator, CDK1. Cell cycle re-entry is highly coordinated and mediated by a set of early responsive transcripts involving NIMA and Aurora kinases, ApiAP2 transcription factors and calcium signaling. We therefore show that Apicomplexa are able to perform quiescence-proliferation decision-making in a highly coordinated fashion, using atypical cell cycle regulation machinery.
2016-12-13 | GSE92289 | GEO
Project description:Cellular proliferation is highly regulated to ensure proper tissue homeostasis and to prevent diseases such as cancer. In actively proliferating cells, entry into S phase of the cell cycle and initiation of DNA replication is promoted by inactivation of the E3 ubiquitin ligase APC/C (anaphase promoting complex/cyclosome), though the critical S phase-promoting substrates have not been fully elucidated. The APC/C is also active in cells that have exited the cell cycle and entered an arrested state, but whether APC/C activity is essential to maintain arrest is unclear. We found that APC/C inactivation is sufficient to bypass cellular arrest induced by the CDK4/6 inhibitor Palbociclib. To identify potential APC/C substrates responsible for driving the escape from cell cycle arrest, we arrested cells using Palbociclib and then induced EMI1, inactivating the APC/C. Samples were collected at 0, 8, 16 and 20h after arrest and analyzed using proteomics. We found that inactivation of the APC/C promotes cell cycle re-entry by inducing RB phosphorylation and E2F-dependent gene transcription. Stabilization of both cyclin A and cyclin B contributes to arrest bypass, but only cyclin A accumulation is absolutely required. Direct expression of APC/C-resistant cyclin A, but not cyclin B, in arrested cells induces S phase entry analogous to APC/C inactivation. Cells bypassing arrest initiate DNA replication with severely reduced origin licensing, at least in part due to premature geminin accumulation. As a result, cells exhibit reduced rates of DNA synthesis, which leads to the accumulation of replication stress and long-term proliferation defects. Our findings suggest that CDK4/6 inhibition in cancers with reduced APC/C activity may be ineffective at promoting cytostatic cell cycle arrest but may nonetheless lead to elevated levels of replication stress that ultimately leads to a more durable cell cycle withdrawal.
2024-07-18 | PXD046783 | Pride
Project description:Background: Eukaryotic cells must inhibit re-initiation of DNA replication at each of the thousands of origins in their genome because re-initiation events can generate genomic alterations with extraordinary frequency. To minimize the probability of re-initiation from so many origins, cells use a battery of regulatory mechanisms that reduce the activity of replication initiation proteins. Given the global nature of these mechanisms, it has been presumed that all origins are inhibited identically. However, transiently disabling these mechanisms causes replication origins to re-initiate with diverse efficiencies, which do not correlate with known differences in the efficiency or timing of origin initiation during normal DNA replication. These observations suggest an additional local layer of replication control that can differentially influence how re-initiation is regulated at distinct origins. Principal Findings: We have identified novel genetic elements that are necessary for preferential re-initiation of two origins and sufficient to confer preferential re-initiation on heterologous origins when the control of re-initiation is partially deregulated. The elements do not enhance the S phase timing or efficiency of adjacent origins and thus are specifically acting as re-initiation promoters (RIPs). We have mapped the two RIPs to ~60bp AT rich sequences that act in a distance- and sequence-dependent manner. During the induction of re-replication, Mcm2-7 re-associates both with origins that preferentially re-initiate and origins that do not, suggesting that the RIP elements can overcome a block to re-initiation imposed after Mcm2-7 associates with origins. Conclusions/Significance: We have uncovered a local level of control in the block to re-initiation. This local control creates a complex genomic landscape of re-replication potential that is revealed when global mechanisms preventing re-replication are peeled away. Hence, if re-replication does contribute to genomic alterations, as has been speculated for cancer cells, some regions of the genome may be more susceptible to these alterations than others. 142 array CGH experiments are presented. Each experiment is done in experimental replicate. Cells grown as described in Richardson CD and Li JJ PLoS Genetics 2014. Ch1 samples taken from replicating (S phase) or re-replicating (M phase + 3/6 hour induced). Ch2 samples taken from M phase arrested DNA.
2014-03-15 | E-GEOD-55420 | biostudies-arrayexpress