scholarly journals Cdc28 tyrosine phosphorylation and the morphogenesis checkpoint in budding yeast.

1996 ◽  
Vol 7 (11) ◽  
pp. 1657-1666 ◽  
Author(s):  
R A Sia ◽  
H A Herald ◽  
D J Lew
Keyword(s):  
Cell Cycle ◽  
Translational Regulation ◽  
Cell Cycle Progression ◽  
Nuclear Division ◽  
Budding Yeast ◽  
Mrna Levels ◽  
Gene Encoding ◽  
Cycle Progression ◽  
Morphogenesis Checkpoint ◽  
In Cells

A morphogenesis checkpoint in budding yeast delays nuclear division (and subsequent cell cycle progression) in cells that have failed to make a bud. We show that the ability of this checkpoint to delay nuclear division requires the SWE1 gene, encoding a protein kinase that inhibits the master cell cycle regulatory kinase Cdc28. The timing of nuclear division in cells that cannot make a bud is exquisitely sensitive to the dosage of SWE1 and MIH1 genes, which control phosphorylation of Cdc28 at tyrosine 19. In contrast, the timing of nuclear division in budded cells does not rely on Cdc28 phosphorylation, suggesting that the morphogenesis checkpoint somehow turns on this regulatory pathway. We show that SWE1 mRNA levels fluctuate during the cell cycle and are elevated in cells that cannot make a bud. However, regulation of SWE1 mRNA levels by the checkpoint is indirect, acting through a feedback loop requiring Swe1 activity. Further, the checkpoint is capable of delaying nuclear division even when SWE1 transcription is deregulated. We propose that the checkpoint delays nuclear division through post-translational regulation of Swe1 and that transcriptional feedback loops enhance the efficacy of the checkpoint.

scholarly journals Mathematical model of the morphogenesis checkpoint in budding yeast

2003 ◽  
Vol 163 (6) ◽  
pp. 1243-1254 ◽  
Author(s):  
Andrea Ciliberto ◽  
Bela Novak ◽  
John J. Tyson
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Budding Yeast ◽  
Cyclin Dependent Kinase ◽  
Cycle Progression ◽  
Bud Formation ◽  
Control Signals ◽  
Potent Inhibition ◽  
Morphogenesis Checkpoint ◽  
Size Threshold

The morphogenesis checkpoint in budding yeast delays progression through the cell cycle in response to stimuli that prevent bud formation. Central to the checkpoint mechanism is Swe1 kinase: normally inactive, its activation halts cell cycle progression in G2. We propose a molecular network for Swe1 control, based on published observations of budding yeast and analogous control signals in fission yeast. The proposed Swe1 network is merged with a model of cyclin-dependent kinase regulation, converted into a set of differential equations and studied by numerical simulation. The simulations accurately reproduce the phenotypes of a dozen checkpoint mutants. Among other predictions, the model attributes a new role to Hsl1, a kinase known to play a role in Swe1 degradation: Hsl1 must also be indirectly responsible for potent inhibition of Swe1 activity. The model supports the idea that the morphogenesis checkpoint, like other checkpoints, raises the cell size threshold for progression from one phase of the cell cycle to the next.

scholarly journals Wobble Inosine tRNA Modification Is Essential to Cell Cycle Progression in G1/S and G2/M Transitions in Fission Yeast

2007 ◽  
Vol 282 (46) ◽  
pp. 33459-33465 ◽  
Author(s):  
Satoshi Tsutsumi ◽  
Reiko Sugiura ◽  
Yan Ma ◽  
Hideki Tokuoka ◽  
Kazuki Ohta ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Cell Cycle Progression ◽  
Budding Yeast ◽  
Temperature Sensitive ◽  
Trna Modification ◽  
Gene Encoding ◽  
Cycle Progression ◽  
Catalytically Active ◽  
Mutant Cells

Inosine (I) at position 34 (wobble position) of tRNA is formed by the hydrolytic deamination of a genomically encoded adenosine (A). The enzyme catalyzing this reaction, termed tRNA A:34 deaminase, is the heterodimeric Tad2p/ADAT2·Tad3p/ADAT3 complex in eukaryotes. In budding yeast, deletion of each subunit is lethal, indicating that the wobble inosine tRNA modification is essential for viability; however, most of its physiological roles remain unknown. To identify novel cell cycle mutants in fission yeast, we isolated the tad3-1 mutant that is allelic to the tad3+ gene encoding a homolog of budding yeast Tad3p. Interestingly, the tad3-1 mutant cells principally exhibited cell cycle-specific phenotype, namely temperature-sensitive and irreversible cell cycle arrest both in G1 and G2. Further analyses revealed that in the tad3-1 mutant cells, the S257N mutation that occurred in the catalytically inactive Tad3 subunit affected its association with catalytically active Tad2 subunit, leading to an impairment in the A to I conversion at position 34 of tRNA. In tad3-1 mutant cells, the overexpression of the tad3+ gene completely suppressed the decreased tRNA inosine content. Notably, the overexpression of the tad2+ gene partially suppressed the temperature-sensitive phenotype and the decreased tRNA inosine content, indicating that the tad3-1 mutant phenotype is because of the insufficient I34 formation of tRNA. These results suggest that the wobble inosine tRNA modification is essential for cell cycle progression in the G1/S and G2/M transitions in fission yeast.

scholarly journals Budding yeast relies on G1 cyclin specificity to couple cell cycle progression with morphogenetic development

2021 ◽  
Vol 7 (23) ◽  
pp. eabg0007
Author(s):  
Deniz Pirincci Ercan ◽  
Florine Chrétien ◽  
Probir Chakravarty ◽  
Helen R. Flynn ◽  
Ambrosius P. Snijders ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Budding Yeast ◽  
Quantitative Model ◽  
Cyclin Dependent Kinase ◽  
Cycle Progression ◽  
Model Cell ◽  
Mitotic Cyclin ◽  
Substrate Phosphorylation ◽  
The Cost

Two models have been put forward for cyclin-dependent kinase (Cdk) control of the cell cycle. In the qualitative model, cell cycle events are ordered by distinct substrate specificities of successive cyclin waves. Alternatively, in the quantitative model, the gradual rise of Cdk activity from G1 phase to mitosis leads to ordered substrate phosphorylation at sequential thresholds. Here, we study the relative contributions of qualitative and quantitative Cdk control in Saccharomyces cerevisiae. All S phase and mitotic cyclins can be replaced by a single mitotic cyclin, albeit at the cost of reduced fitness. A single cyclin can also replace all G1 cyclins to support ordered cell cycle progression, fulfilling key predictions of the quantitative model. However, single-cyclin cells fail to polarize or grow buds and thus cannot survive. Our results suggest that budding yeast has become dependent on G1 cyclin specificity to couple cell cycle progression to essential morphogenetic events.

scholarly journals Structure of the human TIMP-3 gene and its cell cycle-regulated promoter

1995 ◽  
Vol 311 (2) ◽  
pp. 549-554 ◽  
Author(s):  
M Wick ◽  
R Härönen ◽  
D Mumberg ◽  
C Bürger ◽  
B R Olsen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Alternative Polyadenylation ◽  
Regulatory Elements ◽  
Detailed Knowledge ◽  
Gene Encoding ◽  
Cycle Progression ◽  
Physiological Processes ◽  
Cycle Regulation

The gene encoding tissue inhibitor of metalloproteinases-3 (TIMP-3) is regulated during development, mitogenic stimulation and normal cell cycle progression. The TIMP-3 gene is structurally altered or deregulated in certain diseases of the eye and in tumour cells. A detailed knowledge of the TIMP-3 gene and its regulatory elements is therefore of paramount importance to understand its role in development, cell cycle progression and disease. In this study, we present the complete structure of the human TIMP-3 gene. We show that TIMP-3 is a TATA-less gene, which initiates transcription at one major site, is composed of five exons and four introns spanning a region of approximately 30 kb, and gives rise to three distinct mRNAs, presumably due to the usage of alternative polyadenylation signals. Using somatic cell hybrids the TIMP-3 locus was mapped to chromosomal location 22q13.1 We also show that the TIMP-3 5′ flanking region is sufficient to confer both high basal level expression in growing cells and cell cycle regulation in serum-stimulated cells. While the first 112 bases of the promoter, which harbour multiple Sp1 sites, were found to suffice for high basal level activity, the adjacent region spanning positions -463 and -112 was found to be a major determinant of serum inducibility. These results provide an important basis for further investigations addressing the role of TIMP-3 in physiological processes and pathological conditions.

Evaluation of GPER agonist G-1 combined with navitoclax in platinum-resistant and -sensitive ovarian cancer cells.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e13563-e13563
Author(s):  
Dennis C. DeSimone ◽  
Trung T. Nguyen ◽  
Eugen Brailiou ◽  
John C. Taylor ◽  
Gabriela Cristina Brailoiu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Ovarian Cancer ◽  
Cancer Cells ◽  
Cell Cycle Progression ◽  
Parp Cleavage ◽  
Ovarian Cancer Cells ◽  
Cycle Progression ◽  
Platinum Based Chemotherapy ◽  
Induced Apoptosis ◽  
In Cells

e13563 Background: Most ovarian cancer patients are treated with platinum-based chemotherapy but eventually relapse with incurable disease. The G protein-coupled estrogen receptor GPER (GPR30) mediates Ca2+ mobilization in response to estrogen and G-1, a synthetic agonist. Large and sustained Ca2+ responses can lead to mitochondrial Ca2+ overload and apoptosis. Hence, we evaluated whether G-1 could induce apoptosis in cisplatin-sensitive A2780 and isogenic cisplatin–resistant CP70 (14-fold resistant), C30 (70-fold resistant) and C200 (157-fold resistant) human ovarian cancer cells. Bcl-2 and Bcl-xL protect mitochondria from Ca2+overload, and were overexpressed in these cisplatin-resistant cells; thus we also examined combining the Bcl-2 family inhibitor navitoclax with G-1. Methods: Cytoplasmic [Ca2+]c and mitochondrial [Ca2+]m were monitored using microscopy and fluorescent Ca2+ probes. Cell cycle, apoptosis and mitochondrial membrane potential (MMP) were assessed by flow cytometry of propidium iodide, Annexin V and DiIC1(5) -stained cells. The intracellular Ca2+ chelator BAPTA was used to block Ca2+mobilization. Results: Expression of the 53kDa GPER but not the 38 kDa isoform progressively increased with increasing cisplatin resistance. G-1 elicited sustained [Ca2+]c rises that correlated with 53 kDa GPER expression, followed by rises in [Ca2+]m. In all cells, 2.5 μM G-1 blocked cell cycle progression at G2/M, inhibited proliferation, and induced apoptosis (A2780 > C30 > CP70 ≥ C200). G-1 induced p53, caspase-3 and PARP cleavage, and MMP loss. BAPTA prevented G-1’s cell cycle and apoptotic effects in cells showing large Ca2+ mobilization responses but did not in cells with small Ca2+responses. Combining navitoclax with G-1 superadditively decreased cell viability and increased apoptosis. Conclusions: G-1 blocked cell cycle progression and induced apoptosis via a Ca2+-dependent pathway in cells expressing high 53 kDa GPER levels, but via a Ca2+-independent pathway in cells with low 53 kDa GPER expression. G-1 also interacted cooperatively with naviticlax. Therefore, G-1 plus navitoclax shows potential for therapeutic use in platinum-sensitive and -resistant ovarian cancer.

scholarly journals Budding Yeast Bub2 Is Localized at Spindle Pole Bodies and Activates the Mitotic Checkpoint via a Different Pathway from Mad2

1999 ◽  
Vol 145 (5) ◽  
pp. 979-991 ◽  
Author(s):  
Roberta Fraschini ◽  
Elisa Formenti ◽  
Giovanna Lucchini ◽  
Simonetta Piatti
Keyword(s):  
Cell Cycle ◽  
Mitotic Spindle ◽  
Cell Cycle Progression ◽  
Budding Yeast ◽  
Spindle Pole Body ◽  
Mitotic Checkpoint ◽  
Spindle Pole ◽  
Cycle Progression ◽  
Spindle Pole Bodies

The mitotic checkpoint blocks cell cycle progression before anaphase in case of mistakes in the alignment of chromosomes on the mitotic spindle. In budding yeast, the Mad1, 2, 3, and Bub1, 2, 3 proteins mediate this arrest. Vertebrate homologues of Mad1, 2, 3, and Bub1, 3 bind to unattached kinetochores and prevent progression through mitosis by inhibiting Cdc20/APC-mediated proteolysis of anaphase inhibitors, like Pds1 and B-type cyclins. We investigated the role of Bub2 in budding yeast mitotic checkpoint. The following observations indicate that Bub2 and Mad1, 2 probably activate the checkpoint via different pathways: (a) unlike the other Mad and Bub proteins, Bub2 localizes at the spindle pole body (SPB) throughout the cell cycle; (b) the effect of concomitant lack of Mad1 or Mad2 and Bub2 is additive, since nocodazole-treated mad1 bub2 and mad2 bub2 double mutants rereplicate DNA more rapidly and efficiently than either single mutant; (c) cell cycle progression of bub2 cells in the presence of nocodazole requires the Cdc26 APC subunit, which, conversely, is not required for mad2 cells in the same conditions. Altogether, our data suggest that activation of the mitotic checkpoint blocks progression through mitosis by independent and partially redundant mechanisms.

Functional and molecular identification of intermediate-conductance Ca2+-activated K+ channels in breast cancer cells: association with cell cycle progression

2004 ◽  
Vol 287 (1) ◽  
pp. C125-C134 ◽  
Author(s):  
Halima Ouadid-Ahidouch ◽  
Morad Roudbaraki ◽  
Philippe Delcourt ◽  
Ahmed Ahidouch ◽  
Nathalie Joury ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Membrane Potential ◽  
Current Density ◽  
Cell Cycle Progression ◽  
G1 Phase ◽  
Cycle Progression ◽  
Mcf 7 ◽  
In Cells

We have previously reported that the hEAG K+ channels are responsible for the potential membrane hyperpolarization that induces human breast cancer cell progression into the G1 phase of the cell cycle. In the present study, we evaluate the role and functional expression of the intermediate-conductance Ca2+-activated K+ channel, hIK1-like, in controlling cell cycle progression. Our results demonstrate that hIK1 current density increased in cells synchronized at the end of the G1 or S phase compared with those in the early G1 phase. This increased current density paralleled the enhancement in hIK1 mRNA levels and the highly negative membrane potential. Furthermore, in cells synchronized at the end of G1 or S phases, basal cytosolic Ca2+ concentration ([Ca2+]i) was also higher than in cells arrested in early G1. Blocking hIK1 channels with a specific blocker, clotrimazole, induced both membrane potential depolarization and a decrease in the [Ca2+]i in cells arrested at the end of G1 and S phases but not in cells arrested early in the G1 phase. Blocking hIK1 with clotrimazole also induced cell proliferation inhibition but to a lesser degree than blocking hEAG with astemizole. The two drugs were essentially additive, inhibiting MCF-7 cell proliferation by 82% and arresting >90% of cells in the G1 phase. Thus, although the progression of MCF-7 cells through the early G1 phase is dependent on the activation of hEAG K+ channels, when it comes to G1 and checkpoint G1/S transition, the membrane potential appears to be primarily dependent on the hIK1-activity level.

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