A novel mutant allele of the chromatin-bound fission yeast checkpoint protein Rad17 separates the DNA structure checkpoints

2000 ◽  
Vol 113 (6) ◽  
pp. 1075-1088
Author(s):  
D. Griffiths ◽  
M. Uchiyama ◽  
P. Nurse ◽  
T.S. Wang
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Radiation Sensitivity ◽  
S Phase ◽  
Temperature Sensitive ◽  
Dna Polymerase Delta ◽  
Synthesis Inhibitor ◽  
Cycle Arrest ◽  
Checkpoint Pathway ◽  
Higher Doses

To further dissect the genetic differences between the checkpoint pathway following S-phase cdc arrest versus DNA damage, a genetic screen was performed for checkpoint mutants that were unable to arrest mitosis following cell-cycle arrest with a temperature-sensitive DNA polymerase delta mutant, cdc20-M10. One such checkpoint mutant, rad17-d14, was found to display the cut phenotype following S-phase arrest by cdc20-M10, but not by the DNA synthesis inhibitor hydroxyurea, reminiscent of the chk1 mutant. Unlike chk1, rad17-d14 was not sensitive to UV irradiation. Interestingly, the ionising radiation sensitivity of rad17-d14 was only at higher doses, and cells were found to be defective in properly arresting cell division following irradiation in S phase, but not G(2) phase. Biochemical analysis attributes the checkpoint defects of rad17-d14 to the failure to phosphorylate the checkpoint effector Chk1p. To investigate if Rad17p monitors the genome for abnormal DNA structures specifically during DNA synthesis, chromatin association of Rad17p was analysed. Rad17p was found to be chromatin associated throughout the cell cycle, not just during S phase. This interaction occurred irrespective of the arrest with cdc20-M10 and, surprisingly, was also independent of the other checkpoint Rad proteins, and the cell-cycle effectors Chk1p and Cds1p.

The Schizosaccharomyces pombe hus5 gene encodes a ubiquitin conjugating enzyme required for normal mitosis

1995 ◽  
Vol 108 (2) ◽  
pp. 475-486 ◽  
Author(s):  
F. al-Khodairy ◽  
T. Enoch ◽  
I.M. Hagan ◽  
A.M. Carr
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Schizosaccharomyces Pombe ◽  
Cell Cycle Control ◽  
S Phase ◽  
Temperature Sensitive ◽  
Checkpoint Control ◽  
Ubiquitin Conjugating Enzyme ◽  
Efficient Recovery ◽  
Mediate Cell

Normal eukaryotic cells do not enter mitosis unless DNA is fully replicated and repaired. Controls called ‘checkpoints’, mediate cell cycle arrest in response to unreplicated or damaged DNA. Two independent Schizosaccharomyces pombe mutant screens, both of which aimed to isolate new elements involved in checkpoint controls, have identified alleles of the hus5+ gene that are abnormally sensitive to both inhibitors of DNA synthesis and to ionizing radiation. We have cloned and sequenced the hus5+ gene. It is a novel member of the E2 family of ubiquitin conjugating enzymes (UBCs). To understand the role of hus5+ in cell cycle control we have characterized the phenotypes of the hus5 mutants and the hus5 gene disruption. We find that, whilst the mutants are sensitive to inhibitors of DNA synthesis and to irradiation, this is not due to an inability to undergo mitotic arrest. Thus, the hus5+ gene product is not directly involved in checkpoint control. However, in common with a large class of previously characterized checkpoint genes, it is required for efficient recovery from DNA damage or S-phase arrest and manifests a rapid death phenotype in combination with a temperature sensitive S phase and late S/G2 phase cdc mutants. In addition, hus5 deletion mutants are severely impaired in growth and exhibit high levels of abortive mitoses, suggesting a role for hus5+ in chromosome segregation. We conclude that this novel UBC enzyme plays multiple roles and is virtually essential for cell proliferation.

scholarly journals The NUCKS1-SKP2-p21/p27 axis controls S phase entry

2021 ◽  
Author(s):  
Samuel Hume ◽  
Claudia P Grou ◽  
Pauline Lascaux ◽  
Vincenzo D'Angiolella ◽  
Arnaud J Legrand ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Ubiquitin Ligase ◽  
Transcriptional Repression ◽  
S Phase ◽  
Tissue Homeostasis ◽  
Cycle Arrest ◽  
Checkpoint Pathway ◽  
Dna Damage Signalling ◽  
Phase Entry

Efficient entry into S phase of the cell cycle is necessary for embryonic development and tissue homeostasis. However, unscheduled S phase entry triggers DNA damage and promotes oncogenesis, underlining the requirement for strict control. Here, we identify the NUCKS1-SKP2-p21/p27 axis as a checkpoint pathway for the G1/S transition. In response to mitogenic stimulation, NUCKS1, a transcription factor, is recruited to chromatin to activate expression of SKP2, the F-box component of the SCFSKP2 ubiquitin ligase, leading to degradation of p21 and p27 and promoting progression into S phase. In contrast, DNA damage induces p53-dependent transcriptional repression of NUCKS1, leading to SKP2 downregulation, p21/p27 upregulation, and cell cycle arrest. We propose that the NUCKS1-SKP2-p21/p27 axis integrates mitogenic and DNA damage signalling to control S phase entry. TCGA data reveal that this mechanism is hijacked in cancer, potentially allowing cancer cells to sustain uncontrolled proliferation.

scholarly journals Cell Cycle Dysregulation by Human Cytomegalovirus: Influence of the Cell Cycle Phase at the Time of Infection and Effects on Cyclin Transcription

1998 ◽  
Vol 72 (5) ◽  
pp. 3729-3741 ◽  
Author(s):  
Bryan S. Salvant ◽  
Elizabeth A. Fortunato ◽  
Deborah H. Spector
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
Hcmv Infection ◽  
Cyclin A ◽  
S Phase ◽  
Cyclin B ◽  
Cycle Progression ◽  
Cycle Arrest ◽  
Time Of Infection

ABSTRACT Human cytomegalovirus (HCMV) infection inhibits cell cycle progression and alters the expression of cyclins E, A, and B (F. M. Jault, J.-M. Jault, F. Ruchti, E. A. Fortunato, C. Clark, J. Corbeil, D. D. Richman, and D. H. Spector, J. Virol. 69:6697–6704, 1995). In this study, we examined cell cycle progression, cyclin gene expression, and early viral events when the infection was initiated at different points in the cell cycle (G0, G1, and S). In all cases, infection led to cell cycle arrest. Cells infected in G0 or G1phase also showed a complete or partial absence, respectively, of cellular DNA synthesis at a time when DNA synthesis occurred in the corresponding mock-infected cells. In contrast, when cells were infected near or during S phase, many cells were able to pass through S phase and undergo mitosis prior to cell cycle arrest. S-phase infection also produced a delay in the appearance of the viral cytopathic effect and in the synthesis of immediate-early and early proteins. Labeling of cells with bromodeoxyuridine immediately prior to HCMV infection in S phase revealed that viral protein expression occurred primarily in cells which were not engaged in DNA synthesis at the time of infection. The viral-mediated induction of cyclin E, maintenance of cyclin-B protein levels, and inhibitory effects on the accumulation of cyclin A were not significantly affected when infection occurred during different phases of the cell cycle (G0, G1, and S). However, there was a delay in the observed inhibition of cyclin A in cells infected during S phase. This finding was in accord with the pattern of cell cycle progression and delay in viral gene expression associated with S-phase infection. Analysis of the mRNA revealed that the effects of the virus on cyclin E and cyclin A, but not on cyclin B, were primarily at the transcriptional level.

scholarly journals MyoD induced cell cycle arrest is associated with increased nuclear affinity of the Rb protein.

1993 ◽  
Vol 4 (7) ◽  
pp. 705-713 ◽  
Author(s):  
A M Thorburn ◽  
P A Walton ◽  
J R Feramisco
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Dna Synthesis ◽  
Cell Cycle Arrest ◽  
S Phase ◽  
Tumor Suppressor Protein ◽  
G1 Phase ◽  
Induced Expression ◽  
Rb Protein ◽  
Cycle Arrest

In studying the mechanism through which the myogenic determination protein MyoD prevents entry into the S phase of the cell cycle, we have found a relationship between MyoD and the retinoblastoma (Rb) tumor suppressor protein. By direct needle microinjection of purified recombinant MyoD protein into quiescent fibroblasts, which were then induced to proliferate by serum, we found that MyoD arrested progression of the cell cycle, in agreement with studies utilizing expression constructs for MyoD. By studying temporal changes in cells injected with MyoD protein, it was found that MyoD did not prevent serum induced expression of the protooncogene c-Fos, an event that occurs in the G0 to G1 transition of the cycle. Injection of the MyoD protein as late as 8 h after the addition of serum still caused an inhibition in DNA synthesis, suggesting that MyoD inhibits the G1 to S transition as opposed to the G0 to G1 transition. MyoD injection did not prevent the expression of cyclin A. However MyoD injection did result in a block in the increase in Rb extractibility normally seen in late G1 phase cells. As this phenomenon is associated with the hyperphosphorylation of Rb at this point in the cell cycle and is correlated with progression into S phase, this provides further evidence that MyoD blocks the cycle late in G1.

scholarly journals The NUCKS1-SKP2-p21/p27 axis controls S phase entry

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Samuel Hume ◽  
Claudia P. Grou ◽  
Pauline Lascaux ◽  
Vincenzo D’Angiolella ◽  
Arnaud J. Legrand ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Transcriptional Repression ◽  
S Phase ◽  
The Cancer Genome Atlas ◽  
Cycle Arrest ◽  
Checkpoint Pathway ◽  
Cancer Genome Atlas ◽  
Dna Damage Signalling ◽  
Phase Entry

AbstractEfficient entry into S phase of the cell cycle is necessary for embryonic development and tissue homoeostasis. However, unscheduled S phase entry triggers DNA damage and promotes oncogenesis, underlining the requirement for strict control. Here, we identify the NUCKS1-SKP2-p21/p27 axis as a checkpoint pathway for the G1/S transition. In response to mitogenic stimulation, NUCKS1, a transcription factor, is recruited to chromatin to activate expression of SKP2, the F-box component of the SCFSKP2 ubiquitin ligase, leading to degradation of p21 and p27 and promoting progression into S phase. In contrast, DNA damage induces p53-dependent transcriptional repression of NUCKS1, leading to SKP2 downregulation, p21/p27 upregulation, and cell cycle arrest. We propose that the NUCKS1-SKP2-p21/p27 axis integrates mitogenic and DNA damage signalling to control S phase entry. The Cancer Genome Atlas (TCGA) data reveal that this mechanism is hijacked in many cancers, potentially allowing cancer cells to sustain uncontrolled proliferation.

scholarly journals Poly(ADP-ribose) Polymerase Activity Prevents Signaling Pathways for Cell Cycle Arrest after DNA Methylating Agent Exposure

2005 ◽  
Vol 280 (16) ◽  
pp. 15773-15785 ◽  
Author(s):  
Julie K. Horton ◽  
Donna F. Stefanick ◽  
Jana M. Naron ◽  
Padmini S. Kedar ◽  
Samuel H. Wilson
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cell Cycle Arrest ◽  
Signaling Pathways ◽  
Dna Polymerase ◽  
S Phase ◽  
Dna Polymerase Β ◽  
Cycle Arrest ◽  
Parp Activity ◽  
Inhibition Of Dna Synthesis

Mouse fibroblasts, deficient in DNA polymerase β, are hypersensitive to monofunctional DNA methylating agents such as methyl methanesulfonate (MMS). Both wild-type and, in particular, repair-deficient DNA polymerase β null cells are highly sensitized to the cytotoxic effects of MMS by 4-amino-1,8-naphthalimide (4-AN), an inhibitor of poly(ADP-ribose) polymerase (PARP) activity. Experiments with synchronized cells suggest that exposure during S-phase of the cell cycle is required for the 4-AN effect. 4-AN elicits a similar extreme sensitization to the thymidine analog, 5-hydroxymethyl-2′-deoxyuridine, implicating the requirement for an intermediate of DNA repair. In PARP-1-expressing fibroblasts treated with a combination of MMS and 4-AN, a complete inhibition of DNA synthesis is apparent after 4 h, and by 24 h, all cells are arrested in S-phase of the cell cycle. Continuous incubation with 4-AN is required to maintain the cell cycle arrest. Caffeine, an inhibitor of the upstream checkpoint kinases ATM (ataxia telangiectasia-mutated) and ATR (ATM and Rad3-related), has no effect on the early inhibition of DNA synthesis, but cells are no longer able to maintain the block after 8 h. Instead, the addition of caffeine leads to arrest of cells in G2/M rather than S-phase after 24 h. Analysis of signaling pathways in cell extracts reveals an activation of Chk1 after treatment with MMS and 4-AN, which can be suppressed by caffeine. Our results suggest that inhibition of PARP activity results in sensitization to MMS through maintenance of an ATR and Chk1-dependent S-phase checkpoint.

Cell cycle arrest of heat-inactivated ts 2 BALB/C-3T3 mouse fibroblasts, temperature-sensitive for DNA synthesis

1985 ◽  
Vol 161 (2) ◽  
pp. 393-405 ◽  
Author(s):  
Rose Sheinin ◽  
Margaret Dubsky ◽  
Leonard Naismith ◽  
José Sigouin
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cell Cycle Arrest ◽  
Temperature Sensitive ◽  
Mouse Fibroblasts ◽  
Cycle Arrest

scholarly journals A Yeast taf17 Mutant Requires the Swi6 Transcriptional Activator for Viability and Shows Defects in Cell Cycle-Regulated Transcription

Genetics ◽  
2000 ◽  
Vol 154 (4) ◽  
pp. 1561-1576
Author(s):  
Neil Macpherson ◽  
Vivien Measday ◽  
Lynda Moore ◽  
Brenda Andrews
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activation ◽  
Essential Gene ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Synthetic Lethal ◽  
Cycle Arrest ◽  
A Cell ◽  
Allelism Tests ◽  
Complementation Groups

Abstract In Saccharomyces cerevisiae, the Swi6 protein is a component of two transcription factors, SBF and MBF, that promote expression of a large group of genes in the late G1 phase of the cell cycle. Although SBF is required for cell viability, SWI6 is not an essential gene. We performed a synthetic lethal screen to identify genes required for viability in the absence of SWI6 and identified 10 complementation groups of swi6-dependent lethal mutants, designated SLM1 through SLM10. We were most interested in mutants showing a cell cycle arrest phenotype; both slm7-1 swi6Δ and slm8-1 swi6Δ double mutants accumulated as large, unbudded cells with increased 1N DNA content and showed a temperature-sensitive growth arrest in the presence of Swi6. Analysis of the transcript levels of cell cycle-regulated genes in slm7-1 SWI6 mutant strains at the permissive temperature revealed defects in regulation of a subset of cyclin-encoding genes. Complementation and allelism tests showed that SLM7 is allelic with the TAF17 gene, which encodes a histone-like component of the general transcription factor TFIID and the SAGA histone acetyltransferase complex. Sequencing showed that the slm7-1 allele of TAF17 is predicted to encode a version of Taf17 that is truncated within a highly conserved region. The cell cycle and transcriptional defects caused by taf17slm7-1 are consistent with the role of TAFIIs as modulators of transcriptional activation and may reflect a role for TAF17 in regulating activation by SBF and MBF.

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