scholarly journals Separation of phenotypes in mutant alleles of the Schizosaccharomyces pombe cell-cycle checkpoint gene rad1+.

1995 ◽  
Vol 6 (12) ◽  
pp. 1793-1805 ◽  
Author(s):  
G Kanter-Smoler ◽  
K E Knudsen ◽  
G Jimenez ◽  
P Sunnerhagen ◽  
S Subramani
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Schizosaccharomyces Pombe ◽  
Synthetic Lethality ◽  
Cell Cycle Checkpoint ◽  
Site Directed Mutagenesis ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Cycle Checkpoint

The Schizosaccharomyces pombe rad1+ gene is involved in the G2 DNA damage cell-cycle checkpoint and in coupling mitosis to completed DNA replication. It is also required for viability when the cdc17 (DNA ligase) or wee1 proteins are inactivated. We have introduced mutations into the coding regions of rad1+ by site-directed mutagenesis. The effects of these mutations on the DNA damage and DNA replication checkpoints have been analyzed, as well as their associated phenotypes in a cdc17-K42 or a wee1-50 background. For all alleles, the resistance to radiation or hydroxyurea correlates well with the degree of functioning of checkpoint pathways activated by these treatments. One mutation, rad1-S3, completely abolishes the DNA replication checkpoint while partially retaining the DNA damage checkpoint. As single mutants, the rad1-S1, rad1-S2, rad1-S5, and rad1-S6 alleles have a wild-type phenotype with respect to radiation sensitivity and checkpoint functions; however, like the rad1 null allele, the rad1-S1 and rad1-S2 alleles exhibit synthetic lethality at the restrictive temperature with the cdc17-K42 or the wee1-50 mutation. The rad1-S5 and rad1-S6 alleles allow growth at higher temperatures in a cdc17-K42 or wee1-50 background than does wild-type rad1+, and thus behave like "superalleles." In most cases both chromosomal and multi-copy episomal mutant alleles have been investigated, and the agreement between these two states is very good. We provide evidence that the functions of rad1 can be dissociated into three groups by specific mutations. Models for the action of these rad1 alleles are discussed. In addition, a putative negative regulatory domain of rad1 is identified.

scholarly journals Activation of Akt/Protein Kinase B Overcomes a G2/M Cell Cycle Checkpoint Induced by DNA Damage

2002 ◽  
Vol 22 (22) ◽  
pp. 7831-7841 ◽  
Author(s):  
Eugene S. Kandel ◽  
Jennifer Skeen ◽  
Nathan Majewski ◽  
Antonio Di Cristofano ◽  
Pier Paolo Pandolfi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Protein Kinase ◽  
Protein Kinase B ◽  
Es Cells ◽  
Cell Cycle Checkpoint ◽  
Wild Type ◽  
M Cell ◽  
Human Cancers ◽  
Cycle Checkpoint

ABSTRACT Activation of Akt, or protein kinase B, is frequently observed in human cancers. Here we report that Akt activation via overexpression of a constitutively active form or via the loss of PTEN can overcome a G2/M cell cycle checkpoint that is induced by DNA damage. Activated Akt also alleviates the reduction in CDC2 activity and mitotic index upon exposure to DNA damage. In addition, we found that PTEN null embryonic stem (ES) cells transit faster from the G2/M to the G1 phase of the cell cycle when compared to wild-type ES cells and that inhibition of phosphoinositol-3-kinase (PI3K) in HEK293 cells elicits G2 arrest that is alleviated by activated Akt. Furthermore, the transition from the G2/M to the G1 phase of the cell cycle in Akt1 null mouse embryo fibroblasts (MEFs) is attenuated when compared to that of wild-type MEFs. These results indicate that the PI3K/PTEN/Akt pathway plays a role in the regulation of G2/M transition. Thus, cells expressing activated Akt continue to divide, without being eliminated by apoptosis, in the presence of continuous exposure to mutagen and accumulate mutations, as measured by inactivation of an exogenously expressed herpes simplex virus thymidine kinase (HSV-tk) gene. This phenotype is independent of p53 status and cannot be reproduced by overexpression of Bcl-2 or Myc and Bcl-2 but seems to counteract a cell cycle checkpoint mediated by DNA mismatch repair (MMR). Accordingly, restoration of the G2/M cell cycle checkpoint and apoptosis in MMR-deficient cells, through reintroduction of the missing component of MMR, is alleviated by activated Akt. We suggest that this new activity of Akt in conjunction with its antiapoptotic activity may contribute to genetic instability and could explain its frequent activation in human cancers.

Nucleoside diphosphokinase and cell cycle control in the fission yeast Schizosaccharomyces pombe

1983 ◽  
Vol 60 (1) ◽  
pp. 355-365
Author(s):  
J.R. Dickinson
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Enzyme Activity ◽  
Dna Replication ◽  
Schizosaccharomyces Pombe ◽  
S Phase ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Synchronous Cultures ◽  
In The Wild

Centrifugal elutriation was used to prepare synchronous cultures of Schizosaccharomyces pombe. Nucleoside diphosphokinase activity was measured throughout the cell cycle. In the wild-type strain (972) nucleoside diphosphokinase activity doubled in a stepwise fashion. The midpoint of the rise in enzyme activity was at 0.65 of a cycle, 0.29 of a cycle before the next S phase. Synchronous cultures of the mutant wee 1–6 were also prepared. In this strain S phase is delayed, occurring about 0.3 cycle later than in the wild-type. In wee 1–6 the midpoint of the stepwise doubling in nucleoside diphosphokinase activity occurred at 0.084; showing that the rise in enzyme activity is also delayed. Addition of cycloheximide to an exponentially growing culture caused an immediate inhibition of protein synthesis, yet nucleoside diphosphokinase activity continued to increase exponentially for a further 300 min. This indicates that the stepwise doubling of nucleoside diphosphokinase activity during the cell cycle is not achieved by a simple control on protein synthesis. Two temperature-sensitive cdc- mutants were also used: cdc2-33, a mutant whose single genetic lesion results in the twin defects of a loss of mitotic control and a loss of commitment to the cell cycle; and cdc 10–129, which has a defect in DNA replication. In both mutants a temperature shift-up of an asynchronously growing culture from the permissive (25 degrees C) to the restrictive temperature (36.5 degrees C) results in a rapid inhibition of DNA replication. In both mutants nucleoside diphosphokinase continues to increase exponentially. Therefore, although nucleoside diphosphokinase is required for DNA replication, apparently DNA replication is not required for an increase in nucleoside diphosphokinase activity.

scholarly journals Acceleration or Brakes: Which Is Rational for Cell Cycle-Targeting Neuroblastoma Therapy?

Biomolecules ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 750
Author(s):  
Kiyohiro Ando ◽  
Akira Nakagawara
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Progression ◽  
Parp Inhibitors ◽  
Cell Cycle Checkpoint ◽  
Mitotic Catastrophe ◽  
Malignant Neoplasms ◽  
Checkpoint Kinases ◽  
Molecular Features ◽  
Cycle Checkpoint

Unrestrained proliferation is a common feature of malignant neoplasms. Targeting the cell cycle is a therapeutic strategy to prevent unlimited cell division. Recently developed rationales for these selective inhibitors can be subdivided into two categories with antithetical functionality. One applies a “brake” to the cell cycle to halt cell proliferation, such as with inhibitors of cell cycle kinases. The other “accelerates” the cell cycle to initiate replication/mitotic catastrophe, such as with inhibitors of cell cycle checkpoint kinases. The fate of cell cycle progression or arrest is tightly regulated by the presence of tolerable or excessive DNA damage, respectively. This suggests that there is compatibility between inhibitors of DNA repair kinases, such as PARP inhibitors, and inhibitors of cell cycle checkpoint kinases. In the present review, we explore alterations to the cell cycle that are concomitant with altered DNA damage repair machinery in unfavorable neuroblastomas, with respect to their unique genomic and molecular features. We highlight the vulnerabilities of these alterations that are attributable to the features of each. Based on the assessment, we offer possible therapeutic approaches for personalized medicine, which are seemingly antithetical, but both are promising strategies for targeting the altered cell cycle in unfavorable neuroblastomas.

scholarly journals PEA15 Regulates the DNA Damage-Induced Cell Cycle Checkpoint and Oncogene-Directed Transformation

2014 ◽  
Vol 34 (12) ◽  
pp. 2264-2282 ◽  
Author(s):  
A. Nagarajan ◽  
S. K. Dogra ◽  
A. Y. Liu ◽  
M. R. Green ◽  
N. Wajapeyee
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Checkpoint ◽  
Cycle Checkpoint ◽  
Directed Transformation

scholarly journals The Prpl  + Gene Required for Pre-mRNA Splicing in Schizosaccharomyces pombe Encodes a Protein That Contains TPR Motifs and Is Similar to Prp6p of Budding Yeast

Genetics ◽  
1997 ◽  
Vol 147 (1) ◽  
pp. 101-115 ◽  
Author(s):  
Seiichi Urushiyama ◽  
Tokio Tani ◽  
Yasumi Ohshima
Keyword(s):  
Cell Cycle ◽  
Amino Acid ◽  
Schizosaccharomyces Pombe ◽  
Protein Interactions ◽  
Nuclear Export ◽  
Cell Cycle Progression ◽  
Synthetic Lethality ◽  
Cell Cycle Control ◽  
Mrna Splicing ◽  
Restrictive Temperature

Abstract The prp (pre-mRNA processing) mutants of the fission yeast Schizosaccharomyces pombe have a defect in pre-mRNA splicing and accumulate mRNA precursors at a restrictive temperature. One of the prp mutants, prp1-4, also has a defect in poly(A)+ RNA transport. The prp1  + gene encodes a protein of 906 amino acid residues that contains 19 repeats of 34 amino acids termed tetratrico peptide repeat (TPR) motifs, which were proposed to mediate protein-protein interactions. The amino acid sequence of Prplp shares 29.6% identity and 50.6% similarity with that of the PRP6 protein of Saccharomyces cerevisiae, which is a component of the U4/U6 snRNP required for spliceosome assembly. No functional complementation was observed between S. pombe prp1  + and S. cerevisiae PRP6. We examined synthetic lethality of prp1-4 with the other known prp mutations in S. pombe. The results suggest that Prp1p interacts either physically or functionally with Prp4p, Prp6p and Prp13p. Interestingly, the prp1  + gene was found to be identical with the zer1  + gene that functions in cell cycle control. These results suggest that Prp1p/Zer1p is either directly or indirectly involved in cell cycle progression and/or poly(A)+ RNA nuclear export, in addition to pre-mRNA splicing.

DNA damage checkpoint kinases in cancer

2020 ◽  
Vol 22 ◽  
Author(s):  
Hannah L. Smith ◽  
Harriet Southgate ◽  
Deborah A. Tweddle ◽  
Nicola J. Curtin
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Environmental Dna ◽  
Cell Cycle Checkpoint ◽  
Checkpoint Control ◽  
Integrated Network ◽  
Checkpoint Kinases ◽  
G1 Checkpoint ◽  
Cycle Checkpoint ◽  
High Level

Abstract DNA damage response (DDR) pathway prevents high level endogenous and environmental DNA damage being replicated and passed on to the next generation of cells via an orchestrated and integrated network of cell cycle checkpoint signalling and DNA repair pathways. Depending on the type of damage, and where in the cell cycle it occurs different pathways are involved, with the ATM-CHK2-p53 pathway controlling the G1 checkpoint or ATR-CHK1-Wee1 pathway controlling the S and G2/M checkpoints. Loss of G1 checkpoint control is common in cancer through TP53, ATM mutations, Rb loss or cyclin E overexpression, providing a stronger rationale for targeting the S/G2 checkpoints. This review will focus on the ATM-CHK2-p53-p21 pathway and the ATR-CHK1-WEE1 pathway and ongoing efforts to target these pathways for patient benefit.

scholarly journals Plasma membrane/cell wall perturbation activates a novel cell cycle checkpoint during G1 inSaccharomyces cerevisiae

2016 ◽  
Vol 113 (25) ◽  
pp. 6910-6915 ◽  
Author(s):  
Keiko Kono ◽  
Amr Al-Zain ◽  
Lea Schroeder ◽  
Makoto Nakanishi ◽  
Amy E. Ikui
Keyword(s):  
Cell Cycle ◽  
Wound Healing ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Dna Replication ◽  
Membrane Damage ◽  
Cell Cycle Checkpoint ◽  
Plasma Membrane Damage ◽  
Cycle Checkpoint ◽  
Membrane Cell

Cellular wound healing or the repair of plasma membrane/cell wall damage (plasma membrane damage) occurs frequently in nature. Although various cellular perturbations, such as DNA damage, spindle misalignment, and impaired daughter cell formation, are monitored by cell cycle checkpoint mechanisms in budding yeast, whether plasma membrane damage is monitored by any of these checkpoints remains to be addressed. Here, we define the mechanism by which cells sense membrane damage and inhibit DNA replication. We found that the inhibition of DNA replication upon plasma membrane damage requires GSK3/Mck1-dependent degradation of Cdc6, a component of the prereplicative complex. Furthermore, the CDK inhibitor Sic1 is stabilized in response to plasma membrane damage, leading to cell integrity maintenance in parallel with the Mck1-Cdc6 pathway. Cells defective in both Cdc6 degradation and Sic1 stabilization failed to grow in the presence of plasma membrane damage. Taking these data together, we propose that plasma membrane damage triggers G1 arrest via Cdc6 degradation and Sic1 stabilization to promote the cellular wound healing process.

Sign in / Sign up

Export Citation Format

Share Document