scholarly journals The puc1 Cyclin Regulates the G1 Phase of the Fission Yeast Cell Cycle in Response to Cell Size

2000 ◽  
Vol 11 (2) ◽  
pp. 543-554 ◽  
Author(s):  
Cristina Martı́n-Castellanos ◽  
Miguel A. Blanco ◽  
José M. de Prada ◽  
Sergio Moreno
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Cell Size ◽  
Yeast Cells ◽  
G1 Phase ◽  
Close Relative ◽  
Cell Cycle Distribution ◽  
Cdk Inhibitor ◽  
Wild Type ◽  
A Cell

Eukaryotic cells coordinate cell size with cell division by regulating the length of the G1 and G2 phases of the cell cycle. In fission yeast, the length of the G1 phase depends on a precise balance between levels of positive (cig1, cig2, puc1, and cdc13 cyclins) and negative (rum1 and ste9-APC) regulators of cdc2. Early in G1, cyclin proteolysis and rum1 inhibition keep the cdc2/cyclin complexes inactive. At the end of G1, the balance is reversed and cdc2/cyclin activity down-regulates both rum1 and the cyclin-degrading activity of the APC. Here we present data showing that the puc1 cyclin, a close relative of the Cln cyclins in budding yeast, plays an important role in regulating the length of G1. Fission yeast cells lacking cig1 and cig2 have a cell cycle distribution similar to that of wild-type cells, with a short G1 and a long G2. However, when thepuc1 + gene is deleted in this genetic background, the length of G1 is extended and these cells undergo S phase with a greater cell size than wild-type cells. This G1 delay is completely abolished in cells lacking rum1. Cdc2/puc1 function may be important to down-regulate the rum1 Cdk inhibitor at the end of G1.

scholarly journals CLN3 expression is sufficient to restore G1-to-S-phase progression in Saccharomyces cerevisiae mutants defective in translation initiation factor eIF4E

1999 ◽  
Vol 340 (1) ◽  
pp. 135-141 ◽  
Author(s):  
Parisa DANAIE ◽  
Michael ALTMANN ◽  
Michael N. HALL ◽  
Hans TRACHSEL ◽  
Stephen B. HELLIWELL
Keyword(s):  
Cell Cycle ◽  
S Phase ◽  
Translation Initiation Factor ◽  
Yeast Cells ◽  
Initiation Factor ◽  
G1 Phase ◽  
Mrna Levels ◽  
Wild Type ◽  
Phase Progression ◽  
Type Gene

The essential cap-binding protein (eIF4E) of Saccharomycescerevisiae is encoded by the CDC33 (wild-type) gene, originally isolated as a mutant, cdc33-1, which arrests growth in the G1 phase of the cell cycle at 37 °C. We show that other cdc33 mutants also arrest in G1. One of the first events required for G1-to-S-phase progression is the increased expression of cyclin 3. Constructs carrying the 5ʹ-untranslated region of CLN3 fused to lacZ exhibit weak reporter activity, which is significantly decreased in a cdc33-1 mutant, implying that CLN3 mRNA is an inefficiently translated mRNA that is sensitive to perturbations in the translation machinery. A cdc33-1 strain expressing either stable Cln3p (Cln3-1p) or a hybrid UBI4 5ʹ-CLN3 mRNA, whose translation displays decreased dependence on eIF4E, arrested randomly in the cell cycle. In these cells CLN2 mRNA levels remained high, indicating that Cln3p activity is maintained. Induction of a hybrid UBI4 5ʹ-CLN3 message in a cdc33-1 mutant previously arrested in G1 also caused entry into a new cell cycle. We conclude that eIF4E activity in the G1-phase is critical in allowing sufficient Cln3p activity to enable yeast cells to enter a new cell cycle.

Three proteins required for early steps in the protein secretory pathway also affect nuclear envelope structure and cell cycle progression in fission yeast

2002 ◽  
Vol 115 (2) ◽  
pp. 421-431
Author(s):  
Anna Matynia ◽  
Sandra S. Salus ◽  
Shelley Sazer
Keyword(s):  
Cell Cycle ◽  
Nuclear Envelope ◽  
Fission Yeast ◽  
Cell Cycle Progression ◽  
Secretory Pathway ◽  
Yeast Cells ◽  
Ran Gtpase ◽  
A Cell ◽  
Cell Cycle Block ◽  
Er Membrane

The Ran GTPase is an essential protein that has multiple functions in eukaryotic cells. Fission yeast cells in which Ran is misregulated arrest after mitosis with condensed, unreplicated chromosomes and abnormal nuclear envelopes. The fission yeast sns mutants arrest with a similar cell cycle block and interact genetically with the Ran system. sns-A10, sns-B2 and sns-B9 have mutations in the fission yeast homologues of S. cerevisiae Sar1p, Sec31p and Sec53p, respectively, which are required for the early steps of the protein secretory pathway. The three sns mutants accumulate a normally secreted protein in the endoplasmic reticulum (ER), have an increased amount of ER membrane, and the ER/nuclear envelope lumen is dilated. Neither a post-ER block in the secretory pathway, nor ER proliferation caused by overexpression of an integral ER membrane protein, results in a cell cycle-specific defect. Therefore, the arrest seen in sns-A10, sns-B2 and sns-B9 is most likely due to nuclear envelope defects that render the cells unable to re-establish the interphase organization of the nucleus after mitosis. As a consequence, these mutants are unable to decondense their chromosomes or to initiate of the next round of DNA replication.

scholarly journals Fission Yeast Cells Grow Approximately Exponentially

2018 ◽  
Author(s):  
Mary Pickering ◽  
Lauren Nicole Hollis ◽  
Edridge D’Souza ◽  
Nicholas Rhind
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Fission Yeast ◽  
Cell Size ◽  
Exponential Growth ◽  
Cell Biology ◽  
Growth Models ◽  
Growth Period ◽  
Yeast Cells ◽  
Yeast Growth

ABSTRACTHow the rate of cell growth is influenced by cell size is a fundamental question of cell biology. The simple model that cell growth is proportional to cell size, based on the proposition that larger cells have proportionally greater synthetic capacity than smaller cells, leads to the predication that the rate of cell growth increases exponentially with cell size. However, other modes of cell growth, including bilinear growth, have been reported. The distinction between exponential and bilinear growth has been explored in particular detail in the fission yeast Schizosaccharomyces pombe. We have revisited the mode of fission yeast cell growth using high-resolution time-lapse microscopy and find, as previously reported, that these two growth models are difficult to distinguish both because of the similarity in shapes between exponential and bilinear curves over the two-fold change in length of a normal cell cycle and because of the substantial biological and experimental noise inherent to these experiments. Therefore, we contrived to have cells grow more than two fold, by holding them in G2 for up to eight hours. Over this extended growth period, in which cells grow up to 5.5-fold, the two growth models diverge to the point that we can confidently exclude bilinear growth as a general model for fission yeast growth. Although the growth we observe is clearly more complicated than predicted by simple exponential growth, we find that exponential growth is a robust approximation of fission yeast growth, both during an unperturbed cell cycle and during extended periods of growth.

scholarly journals Characterizing non-exponential growth and bimodal cell size distributions in Schizosaccharomyces pombe: an analytical approach

2021 ◽  
Author(s):  
Chen Jia ◽  
Abhyudai Singh ◽  
Ramon Grima
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Cell Size ◽  
Control Strategy ◽  
Size Control ◽  
Birth Size ◽  
Size Distributions ◽  
Cell Size Distribution ◽  
A Cell ◽  
Cell Size Control

Unlike many single-celled organisms, the growth of fission yeast cells within a cell cycle is not exponential. It is rather characterized by three distinct phases (elongation, septation and fission), each with a different growth rate. Experiments also show that the distribution of cell size in a lineage is often bimodal, unlike the unimodal distributions measured for the bacterium Escherichia coli. Here we construct a detailed stochastic model of cell size dynamics in fission yeast. The theory leads to analytic expressions for the cell size and the birth size distributions, and explains the origin of bimodality seen in experiments. In particular our theory shows that the left peak in the bimodal distribution is associated with cells in the elongation phase while the right peak is due to cells in the septation and fission phases. We show that the size control strategy, the variability in the added size during a cell cycle and the fraction of time spent in each of the three cell growth phases have a strong bearing on the shape of the cell size distribution. Furthermore we infer all the parameters of our model by matching the theoretical cell size and birth size distributions to those from experimental single cell time-course data for seven different growth conditions. Our method provides a much more accurate means of determining the cell size control strategy (timer, adder or sizer) than the standard method based on the slope of the best linear fit between the birth and division sizes. We also show that the variability in added size and the strength of cell size control of fission yeast depend weakly on the temperature but strongly on the culture medium.

Analysis of the significance of a periodic, cell size-controlled doubling in rates of macromolecular synthesis for the control of balanced exponential growth of fission yeast cells

1979 ◽  
Vol 35 (1) ◽  
pp. 41-51
Author(s):  
A. Barnes ◽  
P. Nurse ◽  
R.S. Fraser
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Cell Size ◽  
Exponential Growth ◽  
Messenger Rna ◽  
Rna Synthesis ◽  
Cell Mass ◽  
Yeast Cells ◽  
Periodic Cell ◽  
Threshold Size

Mutant strains of the fission yeast Schizosaccharomyces pombe are available which divide at smaller mean sizes than wild type. Earlier work by the present authors has shown that all these strains double their rates of polyadenylated messenger RNA synthesis as a step once in each cell cycle. The smaller the cell, the later in the cycle is the doubling in rate of synthesis. Strains of all sizes, however, double their synthetic rate when at the same threshold size. We show here that the differences in cell cycle stage of doubling in rate of polyadenylated messenger RNA synthesis are enough to explain the reduced mean steady state polyadenylated messenger RNA contents of the smaller strains. The cell size-related control over doubling in rate of synthesis is also shown to maintain the mean polyadenylated messenger RNA content as a constant proportion of cell mass, irrespective of cell size. This control thus allows cells to maintain balanced exponential growth, even when absolute growth rate per cell is altered by mutation. It is also shown that the concentration of polyadenylated messenger RNA itself could act as a monitor of the threshold size triggering the doubling in rate of synthesis in each cell cycle.

Fission yeast Nda1 and Nda4, MCM homologs required for DNA replication, are constitutive nuclear proteins

1996 ◽  
Vol 109 (2) ◽  
pp. 319-326 ◽  
Author(s):  
N. Okishio ◽  
Y. Adachi ◽  
M. Yanagida
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Fission Yeast ◽  
Budding Yeast ◽  
Affinity Column ◽  
Wild Type ◽  
M Phase ◽  
A Cell ◽  
Mcm Proteins ◽  
Cycle Dependent

The nda1+ and nda4+ genes of the fission yeast Schizosaccharomyces pombe encode proteins similar to budding yeast MCM2 and MCM5/CDC46, respectively, which are required for the early stages of DNA replication. The budding yeast Mcm proteins display cell-cycle dependent localization. They are present in the nucleus specifically from late M phase until the beginning of S phase, so that they were suggested to be components of a replication licensing factor, a positive factor for the onset of replication, which is thought to be inactivated after use, thus restricting replication to only once in a cell cycle. In the present study, we raised antibodies against Nda1 or Nda4 and identified 115 kDa and 80 kDa proteins, respectively. Their immunolocalization was examined in wild-type cells and in various cell-cycle mutants. Both Nda1 and Nda4 proteins remained primarily in the nucleus throughout the cell cycle. In mutants arrested in G1, S, and G2 phases, these proteins were also enriched in the nucleus. These results indicate that the dramatic change in subcellular localization as seen in budding yeast is not essential in fission yeast for the functions of Nda1 and Nda4 proteins to be executed. The histidine-tagged nda1+ gene was constructed and integrated into the chromosome to replace the wild-type nda1+ gene. The resulting His-tagged Nda1 protein was adsorbed to the Ni-affinity column, and co-eluted with the untagged Nda4 protein, suggesting that they formed a complex.

scholarly journals Identification of mutants with increased variation in cell size at onset of mitosis in fission yeast

2021 ◽  
pp. jcs.251769
Author(s):  
Elizabeth Wood ◽  
Kazunori Kume ◽  
Francisco J. Navarro ◽  
Paul Nurse
Keyword(s):  
Fission Yeast ◽  
Cell Size ◽  
Wild Type Strain ◽  
Cell Length ◽  
Yeast Cells ◽  
Wild Type ◽  
Gene Deletions ◽  
Cytoplasmic Transport ◽  
Dividing Cells ◽  
The Mean

Fission yeast cells divide at a similar cell length with little variation about the mean. This is thought to be the result of a control mechanism that senses size and corrects for any deviations by advancing or delaying onset of mitosis. Gene deletions that advance cells into mitosis at a smaller size or delay cells entering mitosis, have identified genes potentially involved in this mechanism. However, the molecular basis of this control is still not understood. In this work, we have screened for genes, which when deleted, increase the variability in size of dividing cells. The strongest candidate of this screen was mga2. The mga2 deletion shows a greater variation in cell length at division, with a coefficient of variation (CV) of 15-24% while the wild type strain has a CV of 5-8%. Furthermore, unlike wild type cells, the mga2 deletion cells are unable to correct cell size deviations within one cell cycle. We show that the mga2 gene genetically interacts with nem1 and influences the nuclear membrane, and speculate that it may influence the nucleus/cytoplasmic transport of CDK regulators.

scholarly journals Regulation of Cell Size by Glucose Is Exerted via Repression of the CLN1 Promoter

1998 ◽  
Vol 18 (5) ◽  
pp. 2492-2501 ◽  
Author(s):  
Karin Flick ◽  
Daphne Chapman-Shimshoni ◽  
David Stuart ◽  
Marisela Guaderrama ◽  
Curt Wittenberg
Keyword(s):  
Cell Cycle ◽  
Cell Size ◽  
Transcriptional Repression ◽  
Yeast Cells ◽  
Glucose Addition ◽  
Cell Cycle Delay ◽  
Core Elements ◽  
Dependent Cell ◽  
A Cell

ABSTRACT Yeast cells are keenly sensitive to the availability and quality of nutrients. Addition of glucose to cells growing on a poorer carbon source elicits a cell cycle delay during G1 phase and a concomitant increase in the cell size. The signal is transduced through the RAS-cyclic AMP pathway. Using synchronized populations of G1 cells, we show that the increase in cell size required for budding depends upon CLN1 but not other G1 cyclins. This delay in cell cycle initiation is associated specifically with transcriptional repression of CLN1. CLN2 is not repressed. Repression of CLN1 is not limited to the first cycle following glucose addition but occurs in each cell cycle during growth on glucose. A 106-bp fragment of theCLN1 promoter containing the three MluI cell cycle box (MCB) core elements responsible for the majority ofCLN1-associated upstream activation sequence activity is sufficient to confer glucose-induced repression on a heterologous reporter. A mutant CLN2 promoter that is rendered dependent upon its three MCB core elements due to inactivation of its Swi4-dependent cell cycle box (SCB) elements is also repressed by glucose. The response to glucose is partially suppressed by inactivation of SWI4, but not MBP1, which is consistent with the dependence of MCB core elements upon the SCB-binding transcription factor (SBF). We suggest that differential regulation of CLN1 and CLN2 by glucose results from differences in the capacity of SBF to activate transcription driven by SCB and MCB core elements. Finally, we show that transcriptional repression is sufficient to explain the cell cycle delay that occurs in response to glucose.

scholarly journals Size-dependent increase in RNA Polymerase II initiation rates mediates gene expression scaling with cell size

2019 ◽  
Author(s):  
Xi-Ming Sun ◽  
Anthony Bowman ◽  
Miles Priestman ◽  
Francois Bertaux ◽  
Amalia Martinez-Segura ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Fission Yeast ◽  
Rna Polymerase Ii ◽  
Cell Size ◽  
Transcription Initiation ◽  
Molecular Mechanisms ◽  
Single Cells ◽  
Yeast Cells ◽  
Limiting Factor

ABSTRACTCell size varies during the cell cycle and in response to external stimuli. This requires the tight coordination, or “scaling”, of mRNA and protein quantities with the cell volume in order to maintain biomolecules concentrations and cell density. Evidence in cell populations and single cells indicates that scaling relies on the coordination of mRNA transcription rates with cell size. Here we use a combination of single-molecule fluorescence in situ hybridisation (smFISH), time-lapse microscopy and mathematical modelling in single fission yeast cells to uncover the precise molecular mechanisms that control transcription rates scaling with cell size. Linear scaling of mRNA quantities is apparent in single fission yeast cells during a normal cell cycle. Transcription rates of both constitutive and regulated genes scale with cell size without evidence for transcriptional bursting. Modelling and experimental data indicate that scaling relies on the coordination of RNAPII transcription initiation rates with cell size and that RNAPII is a limiting factor. We show using real-time quantitative imaging that size increase is accompanied by a rapid concentration independent recruitment of RNAPII onto chromatin. Finally, we find that in multinucleated cells, scaling is set at the level of single nuclei and not the entire cell, making the nucleus the transcriptional scaling unit. Integrating our observations in a mechanistic model of RNAPII mediated transcription, we propose that scaling of gene expression with cell size is the consequence of competition between genes for limiting RNAPII.

scholarly journals The pro-apoptosis effects of Echinacea purpurea and Cannabis sativa extracts in human lung cancer cells through caspase-dependent pathway

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Fatemeh Hosami ◽  
Azadeh Manayi ◽  
Vahid Salimi ◽  
Farshad Khodakhah ◽  
Mitra Nourbakhsh ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cell Cycle ◽  
Caspase 3 ◽  
Cannabis Sativa ◽  
A549 Cells ◽  
Echinacea Purpurea ◽  
G1 Phase ◽  
Cell Cycle Distribution ◽  
Cb2 Receptor ◽  
Anti Cancer

Abstract Background Considering the advantages of using medicinal herbs as supplementary treatments to sensitize conventional anti-cancer drugs, studying functional mechanisms and regulatory effects of Echinacea purpurea (as a non-cannabinoid plant) and Cannabis sativa (as a cannabinoid plant) are timely and required. The potential effects of such herbs on lung cancer cell growth, apoptosis, cell cycle distribution, cellular reactive oxygen species (ROS) level, caspase activity and their cannabinomimetic properties on the CB2 receptor are addressed in the current study. Methods The cytotoxic effect of both herb extracts on the growth of lung cancer cells (A549) was assessed using the MTT assay. The annexin-V-FITC staining and propidium iodide (PI) staining methods were applied for the detection of apoptosis and cell cycle distribution using flow cytometry. The cellular level of ROS was measured using 7′-dichlorofluorescin diacetate (DCFH-DA) as a fluorescent probe in flow cytometry. The caspase 3 activity was assessed using a colorimetric assay Kit. Results Echinacea purpurea (EP) root extract induced a considerable decrease in A549 viable cells, showing a time and dose-dependent response. The cell toxicity of EP was accompanied by induction of early apoptosis and cell accumulation at the sub G1 phase of the cell cycle. The elevation of cellular ROS level and caspase 3 activity indicate ROS-induced caspase-dependent apoptosis following the treatment of A549 cells by EP extract. The observed effects of EP extract on A549 growth and death were abrogated following blockage of CB2 using AM630, a specific antagonist of the CB2 receptor. Increasing concentrations of Cannabis sativa (CS) induced A549 cell death in a time-dependent manner, followed by induction of early apoptosis, cell cycle arrest at sub G1 phase, elevation of ROS level, and activation of caspase 3. The CB2 blockage caused attenuation of CS effects on A549 cell death which revealed consistency with the effects of EP extract on A549 cells. Conclusions The pro-apoptotic effects of EP and CS extracts on A549 cells and their possible regulatory role of CB2 activity might be attributed to metabolites of both herbs. These effects deserve receiving more attention as alternative anti-cancer agents. Graphical abstract

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