scholarly journals DNA Damage Triggers p21WAF1-dependent Emi1 Down-Regulation That Maintains G2 Arrest

2009 ◽  
Vol 20 (7) ◽  
pp. 1891-1902 ◽  
Author(s):  
Jinho Lee ◽  
Jin Ah Kim ◽  
Valerie Barbier ◽  
Arun Fotedar ◽  
Rati Fotedar
Keyword(s):  
Dna Damage ◽  
Cell Cycle Progression ◽  
Control Cell ◽  
Anaphase Promoting Complex ◽  
Checkpoint Control ◽  
G2 Arrest ◽  
Down Regulation ◽  
Cycle Progression ◽  
M Phase

Several regulatory proteins control cell cycle progression. These include Emi1, an anaphase-promoting complex (APC) inhibitor whose destruction controls progression through mitosis to G1, and p21WAF1, a cyclin-dependent kinase (CDK) inhibitor activated by DNA damage. We have analyzed the role of p21WAF1 in G2-M phase checkpoint control and in prevention of polyploidy after DNA damage. After DNA damage, p21+/+ cells stably arrest in G2, whereas p21−/− cells ultimately progress into mitosis. We report that p21 down-regulates Emi1 in cells arrested in G2 by DNA damage. This down-regulation contributes to APC activation and results in the degradation of key mitotic proteins including cyclins A2 and B1 in p21+/+ cells. Inactivation of APC in irradiated p21+/+ cells can overcome the G2 arrest. siRNA-mediated Emi1 down-regulation prevents irradiated p21−/− cells from entering mitosis, whereas concomitant down-regulation of APC activity counteracts this effect. Our results demonstrate that Emi1 down-regulation and APC activation leads to stable p21-dependent G2 arrest after DNA damage. This is the first demonstration that Emi1 regulation plays a role in the G2 DNA damage checkpoint. Further, our work identifies a new p21-dependent mechanism to maintain G2 arrest after DNA damage.

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 Regulation of Cell Cycle Progression by Growth Factor-Induced Cell Signaling

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3327
Author(s):  
Zhixiang Wang
Keyword(s):  
Cell Cycle ◽  
Growth Factor ◽  
Signaling Pathways ◽  
Tyrosine Kinases ◽  
Cell Cycle Progression ◽  
Phase Cell ◽  
Growth Factor Signaling ◽  
Cycle Progression ◽  
M Phase

The cell cycle is the series of events that take place in a cell, which drives it to divide and produce two new daughter cells. The typical cell cycle in eukaryotes is composed of the following phases: G1, S, G2, and M phase. Cell cycle progression is mediated by cyclin-dependent kinases (Cdks) and their regulatory cyclin subunits. However, the driving force of cell cycle progression is growth factor-initiated signaling pathways that control the activity of various Cdk–cyclin complexes. While the mechanism underlying the role of growth factor signaling in G1 phase of cell cycle progression has been largely revealed due to early extensive research, little is known regarding the function and mechanism of growth factor signaling in regulating other phases of the cell cycle, including S, G2, and M phase. In this review, we briefly discuss the process of cell cycle progression through various phases, and we focus on the role of signaling pathways activated by growth factors and their receptor (mostly receptor tyrosine kinases) in regulating cell cycle progression through various phases.

scholarly journals Cyclin C influences the timing of mitosis in fission yeast

2017 ◽  
Vol 28 (13) ◽  
pp. 1738-1744 ◽  
Author(s):  
Gabor Banyai ◽  
Zsolt Szilagyi ◽  
Vera Baraznenok ◽  
Olga Khorosjutina ◽  
Claes M. Gustafsson
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Rna Polymerase Ii ◽  
Cell Cycle Progression ◽  
Cell Cycle Control ◽  
Mediator Complex ◽  
Cycle Progression ◽  
Cyclin C ◽  
M Phase

The multiprotein Mediator complex is required for the regulated transcription of nearly all RNA polymerase II–dependent genes. Mediator contains the Cdk8 regulatory subcomplex, which directs periodic transcription and influences cell cycle progression in fission yeast. Here we investigate the role of CycC, the cognate cyclin partner of Cdk8, in cell cycle control. Previous reports suggested that CycC interacts with other cellular Cdks, but a fusion of CycC to Cdk8 reported here did not cause any obvious cell cycle phenotypes. We find that Cdk8 and CycC interactions are stabilized within the Mediator complex and the activity of Cdk8-CycC is regulated by other Mediator components. Analysis of a mutant yeast strain reveals that CycC, together with Cdk8, primarily affects M-phase progression but mutations that release Cdk8 from CycC control also affect timing of entry into S phase.

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 Canonical and Alternative Pathways in Cyclin-Dependent Kinase 1/Cyclin B Inactivation upon M-Phase Exit in Xenopus laevis Cell-Free Extracts

2011 ◽  
Vol 2011 ◽  
pp. 1-8
Author(s):  
Jacek Z. Kubiak ◽  
Mohammed El Dika
Keyword(s):  
Cell Cycle ◽  
Xenopus Laevis ◽  
Cell Cycle Progression ◽  
Cyclin B ◽  
Cyclin Dependent Kinase ◽  
Cycle Progression ◽  
Alternative Pathways ◽  
Global View ◽  
M Phase

Cyclin-Dependent Kinase 1 (CDK1) is the major M-phase kinase known also as the M-phase Promoting Factor or MPF. Studies performed during the last decade have shown many details of how CDK1 is regulated and also how it regulates the cell cycle progression. Xenopus laevis cell-free extracts were widely used to elucidate the details and to obtain a global view of the role of CDK1 in M-phase control. CDK1 inactivation upon M-phase exit is a primordial process leading to the M-phase/interphase transition during the cell cycle. Here we discuss two closely related aspects of CDK1 regulation in Xenopus laevis cell-free extracts: firstly, how CDK1 becomes inactivated and secondly, how other actors, like kinases and phosphatases network and/or specific inhibitors, cooperate with CDK1 inactivation to assure timely exit from the M-phase.

scholarly journals Human CTC1 primarily functions in telomere maintenance/protection and promotes CHK1 phosphorylation in response to global replication stress

2020 ◽  
Author(s):  
Stephanie M. Ackerson ◽  
Caroline I. Gable ◽  
Jason A. Stewart
Keyword(s):  
Dna Damage ◽  
Cell Cycle Progression ◽  
Replication Stress ◽  
Telomere Maintenance ◽  
Telomeric Dna ◽  
G2 Arrest ◽  
Cycle Progression ◽  
Dna Damage Signaling ◽  
Genome Wide ◽  
Damage Response

ABSTRACTCST (CTC1-STN1-TEN1) is a heterotrimeric, RPA-like protein that binds to single stranded DNA (ssDNA) and functions in the replication of telomeric and non-telomeric DNA. Previous studies have shown that deletion of CTC1 results in decreased cell proliferation and telomeric DNA damage signaling. However, a detailed analysis of the consequences of conditional CTC1 knockout (KO) have not been fully elucidated. Here, we investigated the effects of CTC1 KO on cell cycle progression, genome-wide replication and activation of the DNA damage response. We find that CTC1 KO results in p53-mediated G2 arrest and increased apoptosis, but not genome-wide replication defects or DNA damage. Instead, the G2 arrest is dependent on the accumulation of telomeric RPA following CTC1 KO, suggesting that the primary function of CST is in telomere end protection and maintenance not genome-wide replication. However, despite increased RPA-ssDNA, global CHK1 phosphorylation was not detected in CTC1 KO cells. Further analysis revealed that CTC1 KO significantly inhibits CHK1 phosphorylation following hydroxyurea-induced replication stress, due to decreased levels of the ATR activator TopBP1. Overall, our results identify that telomere not genome-wide DNA damaging signaling leads to decrease proliferation following CTC1 deletion and that CST promotes ATR-CHK1 signaling through the regulation of TopBP1.

Phenotypic characterization ofDrosophila idamutants: defining the role of APC5 in cell cycle progression

2002 ◽  
Vol 115 (5) ◽  
pp. 949-961 ◽  
Author(s):  
A. M. Bentley ◽  
Byron C. Williams ◽  
Michael L. Goldberg ◽  
Andrew J. Andres
Keyword(s):  
Imaginal Disc ◽  
Cell Cycle Progression ◽  
Cell Types ◽  
Cyclin B ◽  
Phenotypic Characterization ◽  
Anaphase Promoting Complex ◽  
Cycle Progression ◽  
Disc Cells ◽  
A Subunit

We have cloned and characterized the ida gene that is required for proliferation of imaginal disc cells during Drosophila development. IDA is homologous to APC5, a subunit of the anaphase-promoting complex(APC/cyclosome). ida mRNA is detected in most cell types throughout development, but it accumulates to its highest levels during early embryogenesis. A maternal component of IDA is required for the production of eggs and viable embryos. Homozygous ida mutants display mitotic defects: they die during prepupal development, lack all mature imaginal disc structures, and have abnormally small optic lobes. Cytological observations show that ida mutant brains have a high mitotic index and many imaginal cells contain an aneuploid number of aberrant overcondensed chromosomes. However, cells are not stalled in metaphase, as mitotic stages in which chromosomes are orientated at the equatorial plate are never observed. Interestingly, some APC/C-target substrates such as cyclin B are not degraded in ida mutants, whereas others controlling sister-chromatid separation appear to be turned over. Taken together, these results suggest a model in which IDA/APC5 controls regulatory subfunctions of the anaphase-promoting complex.

scholarly journals A methylation-phosphorylation switch determines Plk1 kinase activity and function in DNA damage repair

2019 ◽  
Vol 5 (3) ◽  
pp. eaau7566 ◽  
Author(s):  
Weizhe Li ◽  
Hong-Yan Wang ◽  
Xiaolu Zhao ◽  
Hongguo Duan ◽  
Binghua Cheng ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Cycle Progression ◽  
Kinase Activity ◽  
Critical Role ◽  
Dna Damage Repair ◽  
Cycle Progression ◽  
Sister Chromatids ◽  
Damage Repair ◽  
And Function

Polo-like kinase 1 (Plk1) is a crucial regulator of cell cycle progression; but the mechanism of regulation of Plk1 activity is not well understood. We present evidence that Plk1 activity is controlled by a balanced methylation and phosphorylation switch. The methyltransferase G9a monomethylates Plk1 at Lys209, which antagonizes phosphorylation of T210 to inhibit Plk1 activity. We found that the methyl-deficient Plk1 mutant K209A affects DNA replication, whereas the methyl-mimetic Plk1 mutant K209M prolongs metaphase-to-anaphase duration through the inability of sister chromatids separation. We detected accumulation of Plk1 K209me1 when cells were challenged with DNA damage stresses. Ablation of K209me1 delays the timely removal of RPA2 and RAD51 from DNA damage sites, indicating the critical role of K209me1 in guiding the machinery of DNA damage repair. Thus, our study highlights the importance of a methylation-phosphorylation switch of Plk1 in determining its kinase activity and functioning in DNA damage repair.

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