scholarly journals DNA damage checkpoint dynamics drive cell cycle phase transitions

2017 ◽  
Author(s):  
Hui Xiao Chao ◽  
Cere E. Poovey ◽  
Ashley A. Privette ◽  
Gavin D. Grant ◽  
Hui Yan Chao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Phase Transitions ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Dna Damage Checkpoint ◽  
Cycle Progression ◽  
Dna Damage Checkpoints

ABSTRACTDNA damage checkpoints are cellular mechanisms that protect the integrity of the genome during cell cycle progression. In response to genotoxic stress, these checkpoints halt cell cycle progression until the damage is repaired, allowing cells enough time to recover from damage before resuming normal proliferation. Here, we investigate the temporal dynamics of DNA damage checkpoints in individual proliferating cells by observing cell cycle phase transitions following acute DNA damage. We find that in gap phases (G1 and G2), DNA damage triggers an abrupt halt to cell cycle progression in which the duration of arrest correlates with the severity of damage. However, cells that have already progressed beyond a proposed “commitment point” within a given cell cycle phase readily transition to the next phase, revealing a relaxation of checkpoint stringency during later stages of certain cell cycle phases. In contrast to G1 and G2, cell cycle progression in S phase is significantly less sensitive to DNA damage. Instead of exhibiting a complete halt, we find that increasing DNA damage doses leads to decreased rates of S-phase progression followed by arrest in the subsequent G2. Moreover, these phase-specific differences in DNA damage checkpoint dynamics are associated with corresponding differences in the proportions of irreversibly arrested cells. Thus, the precise timing of DNA damage determines the sensitivity, rate of cell cycle progression, and functional outcomes for damaged cells. These findings should inform our understanding of cell fate decisions after treatment with common cancer therapeutics such as genotoxins or spindle poisons, which often target cells in a specific cell cycle phase.

DNA damage inhibits proteolysis of the B-type cyclin Clb5 in S. cerevisiae

1997 ◽  
Vol 110 (15) ◽  
pp. 1813-1820
Author(s):  
D. Germain ◽  
J. Hendley ◽  
B. Futcher
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Tyrosine Phosphorylation ◽  
Cell Cycle Progression ◽  
Cycle Phase ◽  
Cycle Progression ◽  
Ubiquitin Pathway ◽  
Cyclin Dependent Kinases ◽  
Transition Points ◽  
Checkpoint Genes

Cell cycle progression is mediated by waves of specific cyclin dependent kinases (CDKs) in all eukaryotes. Cyclins are degraded by the ubiquitin pathway of proteolysis. The recent identification of several components of the cyclin proteolysis machinery has highlighted both the importance of proteolysis at multiple transition points in the cell cycle and the involvement of other substrates degraded by the same machinery. In this study, we have investigated the effects of DNA damage on the cyclin proteolytic machinery in Saccharomyces cerevisiae. We find that the half-life of the B-type cyclin Clb5 is markedly increased following DNA damage while that of G1 cyclins is not. This effect is independent of cell cycle phase. Clb5 turnover requires p34CDC28 activity. Stabilisation of Clb5 correlates with an increase in tyrosine phosphorylation of p34CDC28, but stabilisation does not require this tyrosine phosphorylation. The stabilisation is independent of the checkpoint genes Mec1 and Rad53. These observations establish a new link between the regulation of proteolysis and DNA damage.

scholarly journals Evidence that the cell cycle is a series of uncoupled, memoryless phases

2018 ◽  
Author(s):  
Hui Xiao Chao ◽  
Randy I. Fakhreddin ◽  
Hristo K. Shimerov ◽  
Rashmi J. Kumar ◽  
Gaorav P. Gupta ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
Phase 1 ◽  
Cell Cycle Phase ◽  
Cell Cycle Checkpoints ◽  
Cycle Phase ◽  
Erlang Distribution ◽  
Cycle Progression ◽  
Gap Phase

The cell cycle is canonically described as a series of 4 phases: G1 (gap phase 1), S (DNA synthesis), G2 (gap phase 2), and M (mitosis). Various models have been proposed to describe the durations of each phase, including a two-state model with fixed S-G2-M duration and random G1 duration1,2; a “stretched” model in which phase durations are proportional3; and an inheritance model in which sister cells show correlated phase durations2,4. A fundamental challenge is to understand the quantitative laws that govern cell-cycle progression and to reconcile the evidence supporting these different models. Here, we used time-lapse fluorescence microscopy to quantify the durations of G1, S, G2, and M phases for thousands of individual cells from three human cell lines. We found no evidence of correlation between any pair of phase durations. Instead, each phase followed an Erlang distribution with a characteristic rate and number of steps. These observations suggest that each cell cycle phase is memoryless with respect to previous phase durations. We challenged this model by perturbing the durations of specific phases through oncogene activation, inhibition of DNA synthesis, reduced temperature, and DNA damage. Phase durations remained uncoupled in individual cells despite large changes in durations in cell populations. To explain this behavior, we propose a mathematical model in which the independence of cell-cycle phase durations arises from a large number of molecular factors that each exerts a minor influence on the rate of cell-cycle progression. The model predicts that it is possible to force correlations between phases by making large perturbations to a single factor that contributes to more than one phase duration, which we confirmed experimentally by inhibiting cyclin-dependent kinase 2 (CDK2). We further report that phases can show coupling under certain dysfunctional states such as in a transformed cell line with defective cell cycle checkpoints. This quantitative model of cell cycle progression explains the paradoxical observation that phase durations are both inherited and independent and suggests how cell cycle progression may be altered in disease states.

scholarly journals Characterizing and inferring quantitative cell cycle phase in single-cell RNA-seq data analysis

2019 ◽  
Author(s):  
Chiaowen Joyce Hsiao ◽  
PoYuan Tung ◽  
John D. Blischak ◽  
Jonathan E. Burnett ◽  
Kenneth A. Barr ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Single Cell ◽  
Cell Cycle Progression ◽  
Cell Types ◽  
Cell Cycle Phase ◽  
Cellular Heterogeneity ◽  
Cycle Phase ◽  
Cycle Progression ◽  
Cellular Environment

AbstractCellular heterogeneity in gene expression is driven by cellular processes such as cell cycle and cell-type identity, and cellular environment such as spatial location. The cell cycle, in particular, is thought to be a key driver of cell-to-cell heterogeneity in gene expression, even in otherwise homogeneous cell populations. Recent advances in single-cell RNA-sequencing (scRNA-seq) facilitate detailed characterization of gene expression heterogeneity, and can thus shed new light on the processes driving heterogeneity. Here, we combined fluorescence imaging with scRNA-seq to measure cell cycle phase and gene expression levels in human induced pluripotent stem cells (iPSCs). Using these data, we developed a novel approach to characterize cell cycle progression. While standard methods assign cells to discrete cell cycle stages, our method goes beyond this, and quantifies cell cycle progression on a continuum. We found that, on average, scRNA-seq data from only five genes predicted a cell’s position on the cell cycle continuum to within 14% of the entire cycle, and that using more genes did not improve this accuracy. Our data and predictor of cell cycle phase can directly help future studies to account for cell-cycle-related heterogeneity in iPSCs. Our results and methods also provide a foundation for future work to characterize the effects of the cell cycle on expression heterogeneity in other cell types.

scholarly journals Caffeine Stabilises Fission Yeast Wee1 in a Rad24-Dependent Manner but Attenuates Its Expression in Response to DNA Damage

2020 ◽  
Vol 8 (10) ◽  
pp. 1512
Author(s):  
John P. Alao ◽  
Johanna Johansson-Sjölander ◽  
Charalampos Rallis ◽  
Per Sunnerhagen
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Stress Response ◽  
Environmental Stress ◽  
Cell Cycle Progression ◽  
Dependent Manner ◽  
Environmental Stress Response ◽  
Cycle Progression ◽  
Dna Damage Checkpoints ◽  
Wee1 Kinase

The widely consumed neuroactive compound caffeine has generated much interest due to its ability to override the DNA damage and replication checkpoints. Previously Rad3 and its homologues was thought to be the target of caffeine’s inhibitory activity. Later findings indicate that the Target of Rapamycin Complex 1 (TORC1) is the preferred target of caffeine. Effective Cdc2 inhibition requires both the activation of the Wee1 kinase and inhibition of the Cdc25 phosphatase. The TORC1, DNA damage, and environmental stress response pathways all converge on Cdc25 and Wee1. We previously demonstrated that caffeine overrides DNA damage checkpoints by modulating Cdc25 stability. The effect of caffeine on cell cycle progression resembles that of TORC1 inhibition. Furthermore, caffeine activates the Sty1 regulated environmental stress response. Caffeine may thus modulate multiple signalling pathways that regulate Cdc25 and Wee1 levels, localisation and activity. Here we show that the activity of caffeine stabilises both Cdc25 and Wee1. The stabilising effect of caffeine and genotoxic agents on Wee1 was dependent on the Rad24 chaperone. Interestingly, caffeine inhibited the accumulation of Wee1 in response to DNA damage. Caffeine may modulate cell cycle progression through increased Cdc25 activity and Wee1 repression following DNA damage via TORC1 inhibition, as TORC1 inhibition increased DNA damage sensitivity.

scholarly journals The G2-phase enriched lncRNA SNHG26 is necessary for proper cell cycle progression and proliferation

2021 ◽  
Author(s):  
Helle Samdal ◽  
Siv A. Hegre ◽  
Konika Chawla ◽  
Nina-Beate Liabakk ◽  
Per A. Aas ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Rna Polymerase Ii ◽  
Cell Cycle Progression ◽  
Phase Distribution ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Cycle Progression ◽  
Chip Sequencing ◽  
Cell Cycle Phase Distribution ◽  
Regulation Of Cell Cycle

AbstractLong noncoding RNAs (lncRNAs) are involved in the regulation of cell cycle, although only a few have been functionally characterized. By combining RNA sequencing and ChIP sequencing of cell cycle synchronized HaCaT cells we have previously identified lncRNAs highly enriched for cell cycle functions. Based on a cyclic expression profile and an overall high correlation to histone 3 lysine 4 trimethylation (H3K4me3) and RNA polymerase II (Pol II) signals, the lncRNA SNHG26 was identified as a top candidate. In the present study we report that downregulation of SNHG26 affects mitochondrial stress, proliferation, cell cycle phase distribution, and gene expression in cis- and in trans, and that this effect is reversed by upregulation of SNHG26. We also find that the effect on cell cycle phase distribution is cell type specific and stable over time. Results indicate an oncogenic role of SNHG26, possibly by affecting cell cycle progression through the regulation of downstream MYC-responsive genes.

scholarly journals The F-Box Protein Dia2 Regulates DNA Replication

2006 ◽  
Vol 17 (4) ◽  
pp. 1540-1548 ◽  
Author(s):  
Deanna M. Koepp ◽  
Andrew C. Kile ◽  
Swarna Swaminathan ◽  
Veronica Rodriguez-Rivera
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Protein Complexes ◽  
S Phase ◽  
Cycle Progression ◽  
Origin Binding Protein ◽  
Cold Sensitive ◽  
F Box Protein

Ubiquitin-mediated proteolysis plays a key role in many pathways inside the cell and is particularly important in regulating cell cycle transitions. SCF (Skp1/Cul1/F-box protein) complexes are modular ubiquitin ligases whose specificity is determined by a substrate-binding F-box protein. Dia2 is a Saccharomyces cerevisiae F-box protein previously described to play a role in invasive growth and pheromone response pathways. We find that deletion of DIA2 renders cells cold-sensitive and subject to defects in cell cycle progression, including premature S-phase entry. Consistent with a role in regulating DNA replication, the Dia2 protein binds replication origins. Furthermore, the dia2 mutant accumulates DNA damage in both S and G2/M phases of the cell cycle. These defects are likely a result of the absence of SCFDia2 activity, as a Dia2 ΔF-box mutant shows similar phenotypes. Interestingly, prolonging G1-phase in dia2 cells prevents the accumulation of DNA damage in S-phase. We propose that Dia2 is an origin-binding protein that plays a role in regulating DNA replication.

scholarly journals Critical role of SMG7 in activation of the ATR-CHK1 axis in response to genotoxic stress

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kathleen Ho ◽  
Hongwei Luo ◽  
Wei Zhu ◽  
Yi Tang
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Critical Role ◽  
Genotoxic Stress ◽  
Dna Damage Checkpoint ◽  
Cycle Progression ◽  
Essential Step

AbstractCHK1 is a crucial DNA damage checkpoint kinase and its activation, which requires ATR and RAD17, leads to inhibition of DNA replication and cell cycle progression. Recently, we reported that SMG7 stabilizes and activates p53 to induce G1 arrest upon DNA damage; here we show that SMG7 plays a critical role in the activation of the ATR-CHK1 axis. Following genotoxic stress, SMG7-null cells exhibit deficient ATR signaling, indicated by the attenuated phosphorylation of CHK1 and RPA32, and importantly, unhindered DNA replication and fork progression. Through its 14-3-3 domain, SMG7 interacts directly with the Ser635-phosphorylated RAD17 and promotes chromatin retention of the 9-1-1 complex by the RAD17-RFC, an essential step to CHK1 activation. Furthermore, through maintenance of CHK1 activity, SMG7 controls G2-M transition and facilitates orderly cell cycle progression during recovery from replication stress. Taken together, our data reveals SMG7 as an indispensable signaling component in the ATR-CHK1 pathway during genotoxic stress response.

scholarly journals The G(2) DNA damage checkpoint targets both Wee1 and Cdc25

2000 ◽  
Vol 113 (10) ◽  
pp. 1727-1736 ◽  
Author(s):  
J.M. Raleigh ◽  
M.J. O'Connell
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Progression ◽  
Dna Damage Checkpoint ◽  
Checkpoint Control ◽  
Down Regulation ◽  
Cycle Progression ◽  
Cycle Arrest ◽  
Checkpoint Pathway

The onset of mitosis is controlled by the cyclin dependent kinase Cdc2p. Cdc2p activity is controlled through the balance of phosphorylation and dephosphorylation of tyrosine-15 (Y15) by the Wee1p kinase and Cdc25p phosphatase. In the fission yeast Schizosaccharomyces pombe, detection of DNA damage in G(2) activates a checkpoint that prevents entry into mitosis through the maintenance of Y15 phosphorylation of Cdc2p, thus ensuring DNA repair precedes chromosome segregation. The protein kinase Chk1p is the endpoint of this checkpoint pathway. We have previously reported that overexpression of Chk1p causes a wee1(+)-dependent G(2) arrest, and this or irradiation leads to hyperphosphorylation of Wee1p. Moreover, Chk1p directly phosphorylates Wee1p in vitro. These data suggested that Wee1p is a key target of Chk1p action in checkpoint control. However, cells lacking wee1(+) are checkpoint proficient and sustained Chk1p overexpression arrests cell cycle progression independently of Wee1p. Therefore, up-regulation of Wee1p alone cannot enforce a checkpoint arrest. Chk1p can also phosphorylate Cdc25p in vitro. These phosphorylation events are thought to promote the interaction with 14–3-3 proteins the cytoplasmic retention of the 14–3-3/Cdc25p complexes. However, we show here that the G(2) DNA damage checkpoint is intact in cells that regulate mitotic entry independently of Cdc25p. Further, these cells are still sensitive to Chk1p-mediated arrest, and so down-regulation of Cdc25p is also insufficient to regulate checkpoint arrest. Conversely, inactivation of both wee1(+) and cdc25(+)abolishes checkpoint control. We also show that activation of the G(2) DNA damage checkpoint induces a transient increase in Wee1p levels. We conclude that the G(2) DNA damage checkpoint simultaneously signals via both up-regulation of Wee1p and down-regulation of Cdc25p, thus providing a double-lock mechanism to ensure cell cycle arrest and genomic stability.

scholarly journals Melatonin improves the first cleavage of parthenogenetic embryos from vitrified–warmed mouse oocytes potentially by promoting cell cycle progression

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bo Pan ◽  
Izhar Hyder Qazi ◽  
Shichao Guo ◽  
Jingyu Yang ◽  
Jianpeng Qin ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Mrna Levels ◽  
Blastocyst Formation ◽  
Cycle Progression ◽  
Maternal Mrna ◽  
Early Apoptosis ◽  
G2 Phase

Abstract Background This study investigated the effect of melatonin (MT) on cell cycle (G1/S/G2/M) of parthenogenetic zygotes developed from vitrified-warmed mouse metaphase II (MII) oocytes and elucidated the potential mechanism of MT action in the first cleavage of embryos. Results After vitrification and warming, oocytes were parthenogenetically activated (PA) and in vitro cultured (IVC). Then the spindle morphology and chromosome segregation in oocytes, the maternal mRNA levels of genes including Miss, Doc1r, Setd2 and Ythdf2 in activated oocytes, pronuclear formation, the S phase duration in zygotes, mitochondrial function at G1 phase, reactive oxygen species (ROS) level at S phase, DNA damage at G2 phase, early apoptosis in 2-cell embryos, cleavage and blastocyst formation rates were evaluated. The results indicated that the vitrification/warming procedures led to following perturbations 1) spindle abnormalities and chromosome misalignment, alteration of maternal mRNAs and delay in pronucleus formation, 2) decreased mitochondrial membrane potential (MMP) and lower adenosine triphosphate (ATP) levels, increased ROS production and DNA damage, G1/S and S/G2 phase transition delay, and delayed first cleavage, and 3) increased early apoptosis and lower levels of cleavage and blastocyst formation. Our results further revealed that such negative impacts of oocyte cryopreservation could be alleviated by supplementation of warming, recovery, PA and IVC media with 10− 9 mol/L MT before the embryos moved into the 2-cell stage of development. Conclusions MT might promote cell cycle progression via regulation of MMP, ATP, ROS and maternal mRNA levels, potentially increasing the first cleavage of parthenogenetic zygotes developed from vitrified–warmed mouse oocytes and their subsequent development.

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