The size control of fission yeast revisited

1996 ◽  
Vol 109 (12) ◽  
pp. 2947-2957 ◽  
Author(s):  
A. Sveiczer ◽  
B. Novak ◽  
J.M. Mitchison
Keyword(s):  
Fission Yeast ◽  
Kinase Activity ◽  
Size Control ◽  
Time Lapse ◽  
Critical Threshold ◽  
Wild Type ◽  
Linear Rate ◽  
Cycle Times ◽  
Threshold Size ◽  
Histone Kinase

An analysis was made of cell length and cycle time in time-lapse films of the fission yeast Schizosaccharomyces pombe using wild-type (WT) cells and those of various mutants. The more important conclusions about ‘size controls’ are: (1) there is a marker in G2 in WT cells provided by a rate change point (RCP) where the linear rate of length growth increases by approximately 30%. The period before this RCP is dependent on size and can be called a ‘sizer’. The period after the RCP is nearly independent of size and can be called a ‘timer’. The achievement of a critical threshold size is at or near the RCP which is on average at about 0.3 of the cycle (halfway through G2). This is much earlier than was previously believed. (2) The RCP is at about the time when H1 histone kinase activity and the B type cyclin cdc13 start to rise in preparation for mitosis. The RCP is also associated with other metabolic changes. (3) In wee1 mutants, the mitotic size control is replaced by a G1/S size control which is as strong as the mitotic control. As in WT cells, there is a sizer which precedes the RCP followed by a timer but the RCP is at about the G1/S boundary and has a larger increase (approximately 100%) in rate. (4) cdc25 is not an essential part of the size control at mitosis or at the G1/S boundary. (5) Three further situations have been examined in which the mitotic size control has been abolished. First, induction synchronisation by block and release of cdc2 and cdc10. In the largest oversize-cells which are produced, the RCP is pushed back to the beginning of the cycle. There is no sizer period but only a timer. Second, when both the antagonists wee1 and cdc25 are absent in the double mutant wee1-50 cdc25 delta. In this interesting situation there is apparently no mitotic size control and the cycle times are quantised. Third, in rum1 delta wee1-50 where the normal long G1 in wee1 is much reduced, there is probably no size control either in G1 or in G2 causing a continuous shortening of division length from cycle to cycle.

The kinetics of H1 histone kinase activation during the cell cycle of wild-type and wee mutants of the fission yeast Schizosaccharomyces pombe

1994 ◽  
Vol 107 (5) ◽  
pp. 1197-1204 ◽  
Author(s):  
J. Creanor ◽  
J.M. Mitchison
Keyword(s):  
Fission Yeast ◽  
Kinase Activity ◽  
Wild Type ◽  
Kinase Activation ◽  
H1 Histone ◽  
Synchronous Cultures ◽  
Novel Method ◽  
Histone Kinase ◽  
Mutant Cells ◽  
Kinetics Of

H1 histone kinase activity has been followed in selection-synchronised cultures of fission yeast wild-type and wee1 mutant cells, and in induction-synchronised cells of the mutant cdc2-33. The main conclusions are: (1) in all three cases, the peak of activity is near mitosis. (2) The rise in activity is relatively slow starting in wild type at 0.4 of the cycle before mitosis. It is proposed that the beginning of the rise is the first identified event in the mitotic control. (3) The rise is twice as fast in wee and starts nearer to mitosis. (4) In all cases the beginning of the rise is in G2. (5) The fall in activity is also slow, lasting for 0.25 of the cycle, in wild type. Exit from mitosis happens well before activity has fallen to baseline. (6) In a range of size mutants, activity is roughly proportional to cell size. It is suggested that the kinase may have a cytoplasmic function. (7) Estimates have been made of the timing of mitosis in the mutants. In wee, mitosis is 0.14 of the cycle earlier than in wild type because the cells have a longer septated period at the end of the cycle. (8) A novel method has been developed for eliminating the effects of the partial asynchrony in synchronous cultures, without which the kinetic analysis would have been inaccurate.

scholarly journals Size control models of Saccharomyces cerevisiae cell proliferation.

1982 ◽  
Vol 2 (4) ◽  
pp. 361-368 ◽  
Author(s):  
A E Wheals
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Proliferation ◽  
Critical Size ◽  
Transition Probability ◽  
Size Control ◽  
Time Lapse ◽  
Growth Conditions ◽  
Yeast Cells ◽  
Cycle Times ◽  
The Individual

By using time-lapse photomicroscopy, the individual cycle times and sizes at bud emergence were measured for a population of saccharomyces cerevisiae cells growing exponentially under balanced growth conditions in a specially constructed filming slide. There was extensive variability in both parameters for daughter and parent cells. The data on 162 pairs of siblings were analyzed for agreement with the predictions of the transition probability hypothesis and the critical-size hypothesis of yeast cell proliferation and also with a model incorporating both of these hypotheses in tandem. None of the models accounted for all of the experimental data, but two models did give good agreement to all of the data. The wobbly tandem model proposes that cells need to attain a critical size, which is very variable, enabling them to enter a start state from which they exit with first order kinetics. The sloppy size control model suggests that cells have an increasing probability per unit time of traversing start as they increase in size, reaching a high plateau value which is less than one. Both models predict that the kinetics of entry into the cell division sequence will strongly depend on variability in birth size and thus will be quite different for daughters and parents of the asymmetrically dividing yeast cells. Mechanisms underlying these models are discussed.

scholarly journals Cell size-dependent regulation of Wee1 localization by Cdr2 cortical nodes

2017 ◽  
Author(s):  
Corey A. H. Allard ◽  
Hannah E. Opalko ◽  
Ko-Wei Liu ◽  
Uche Medoh ◽  
James B. Moseley
Keyword(s):  
Cell Growth ◽  
Fission Yeast ◽  
Cell Size ◽  
Kinase Activity ◽  
Size Control ◽  
Small Cells ◽  
Mitotic Entry ◽  
Size Dependent ◽  
Biochemical Fractionation ◽  
Mitotic Inhibitor

AbstractCell size control requires mechanisms that link cell growth with Cdk1 activity. In fission yeast, the protein kinase Cdr2 forms cortical nodes that include the Cdk1 inhibitor Wee1, along with the Wee1-inhibitory kinase Cdr1. We investigated how nodes inhibit Wee1 during cell growth. Biochemical fractionation revealed that Cdr2 nodes were megadalton structures enriched for activated Cdr2, which increases in level during interphase growth. In live-cell TIRF movies, Cdr2 and Cdr1 remained constant at nodes over time, but Wee1 localized to nodes in short bursts. Recruitment of Wee1 to nodes required Cdr2 kinase activity and the noncatalytic N-terminus of Wee1. Bursts of Wee1 localization to nodes increased 20-fold as cells doubled in size throughout G2. Size-dependent signaling was due in part to the Cdr2 inhibitor Pom1, which suppressed Wee1 node bursts in small cells. Thus, increasing Cdr2 activity during cell growth promotes Wee1 localization to nodes, where inhibitory phosphorylation of Wee1 by Cdr1 and Cdr2 kinases promotes mitotic entry.SummaryCells turn off the mitotic inhibitor Wee1 to enter into mitosis. This study shows how cell growth progressively inhibits fission yeast Wee1 through dynamic bursts of localization to cortical node structures that contain Wee1 inhibitory kinases.

scholarly journals A mitotic role for a novel fission yeast protein kinase dsk1 with cell cycle stage dependent phosphorylation and localization.

1993 ◽  
Vol 4 (3) ◽  
pp. 247-260 ◽  
Author(s):  
M Takeuchi ◽  
M Yanagida
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Fission Yeast ◽  
Cell Cycle Progression ◽  
Kinase Activity ◽  
Specific Protein ◽  
Wild Type ◽  
Mobility Shift ◽  
Multicopy Suppressor ◽  
Phosphorylation Pattern

The fission yeast dsk1+ gene, a multicopy suppressor for cold-sensitive dis1 mutants, encodes a novel 61-kd protein kinase. It is a phosphoprotein, and phosphoserine is the major phosphorylated amino acid. Hyperphosphorylation of dsk1 causes a mobility shift, resulting in two dsk1-specific protein bands. The phosphorylation pattern is strikingly altered when cell cycle progression is delayed or arrested. The slowly migrating phosphorylated form is prominent in mitotically arrested cells, and the fast migrating form is enriched in interphase-arrested cells. dsk1 is a protein kinase. It auto-phosphorylates as well as phosphorylates myelin basic protein (MBP). Phosphotyrosine as well as phosphoserine/threonine were found in autophosphorylation, but no tyrosine phosphorylation occurs when MBP was used as the substrate. The dsk1 immunoprecipitates from mitotically arrested cells have a several-fold higher kinase activity than that from wild type. The haploid gene disruptant is viable, indicating that the dsk1+ gene is non-essential for viability. High dosage of dsk1+, however, strongly delays the G2/M progression. Immunofluorescence microscopy using anti-dsk1 antibody shows that localization pattern of dsk1 protein strikingly alters depending on cell cycle stages. In G2-arrested cells, dsk1 locates in the cytoplasm, whereas in mitotically arrested cells, nuclear stain is intense. In wild-type cells, nuclear stain is seen only in mitotic cells. Hence dsk1 protein may play an important role in mitotic control by altering cellular location, degree of phosphorylation and kinase activity. We discuss possible roles of dsk1 kinase as an add-on regulator in mitosis.

scholarly journals The CDK Pef1 and protein phosphatase 4 oppose each other for regulating cohesin binding to fission yeast chromosomes

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Adrien Birot ◽  
Marta Tormos-Pérez ◽  
Sabine Vaur ◽  
Amélie Feytout ◽  
Julien Jaegy ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Protein Phosphatase ◽  
Opposite Effect ◽  
Kinase Activity ◽  
Chromosome Structure ◽  
Wild Type ◽  
Human Homologue ◽  
Negative Regulators ◽  
Phosphorylation State ◽  
Fine Tune

Cohesin has essential roles in chromosome structure, segregation and repair. Cohesin binding to chromosomes is catalyzed by the cohesin loader, Mis4 in fission yeast. How cells fine tune cohesin deposition is largely unknown. Here, we provide evidence that Mis4 activity is regulated by phosphorylation of its cohesin substrate. A genetic screen for negative regulators of Mis4 yielded a CDK called Pef1, whose closest human homologue is CDK5. Inhibition of Pef1 kinase activity rescued cohesin loader deficiencies. In an otherwise wild-type background, Pef1 ablation stimulated cohesin binding to its regular sites along chromosomes while ablating Protein Phosphatase 4 had the opposite effect. Pef1 and PP4 control the phosphorylation state of the cohesin kleisin Rad21. The CDK phosphorylates Rad21 on Threonine 262. Pef1 ablation, non-phosphorylatable Rad21-T262 or mutations within a Rad21 binding domain of Mis4 alleviated the effect of PP4 deficiency. Such a CDK/PP4-based regulation of cohesin loader activity could provide an efficient mechanism for translating cellular cues into a fast and accurate cohesin response.

scholarly journals Echinocandin Drugs Induce Differential Effects in Cytokinesis Progression and Cell Integrity

2021 ◽  
Vol 14 (12) ◽  
pp. 1332
Author(s):  
Natalia Yagüe ◽  
Laura Gómez-Delgado ◽  
M. Ángeles Curto ◽  
Vanessa S. D. Carvalho ◽  
M. Belén Moreno ◽  
...  
Keyword(s):  
Cell Death ◽  
Fluorescence Microscopy ◽  
Fission Yeast ◽  
Mechanism Of Action ◽  
Time Lapse ◽  
Cell Lysis ◽  
Cell Integrity ◽  
Wild Type ◽  
Fungicidal Effect ◽  
Sublethal Concentrations

Fission yeast contains three essential β(1,3)-D-glucan synthases (GSs), Bgs1, Bgs3, and Bgs4, with non-overlapping roles in cell integrity and morphogenesis. Only the bgs4+ mutants pbr1-8 and pbr1-6 exhibit resistance to GS inhibitors, even in the presence of the wild-type (WT) sequences of bgs1+ and bgs3+. Thus, Bgs1 and Bgs3 functions seem to be unaffected by those GS inhibitors. To learn more about echinocandins’ mechanism of action and resistance, cytokinesis progression and cell death were examined by time-lapse fluorescence microscopy in WT and pbr1-8 cells at the start of treatment with sublethal and lethal concentrations of anidulafungin, caspofungin, and micafungin. In WT, sublethal concentrations of the three drugs caused abundant cell death that was either suppressed (anidulafungin and micafungin) or greatly reduced (caspofungin) in pbr1-8 cells. Interestingly, the lethal concentrations induced differential phenotypes depending on the echinocandin used. Anidulafungin and caspofungin were mostly fungistatic, heavily impairing cytokinesis progression in both WT and pbr1-8. As with sublethal concentrations, lethal concentrations of micafungin were primarily fungicidal in WT cells, causing cell lysis without impairing cytokinesis. The lytic phenotype was suppressed again in pbr1-8 cells. Our results suggest that micafungin always exerts its fungicidal effect by solely inhibiting Bgs4. In contrast, lethal concentrations of anidulafungin and caspofungin cause an early cytokinesis arrest, probably by the combined inhibition of several GSs.

scholarly journals Mitotic control in the absence of cdc25 mitotic inducer in fission yeast

1999 ◽  
Vol 112 (7) ◽  
pp. 1085-1092 ◽  
Author(s):  
A. Sveiczer ◽  
B. Novak ◽  
J.M. Mitchison
Keyword(s):  
Fission Yeast ◽  
Size Control ◽  
Yeast Cells ◽  
Early Event ◽  
Wild Type ◽  
Rate Limiting Step ◽  
Minimal Cycle ◽  
Novel Method ◽  
Successive Generations ◽  
Rate Limiting

Fission yeast cells tolerate the total absence of the cdc25 mitotic inducer in two cases, either in cdc2-3w or in wee1 genetic backgrounds. In the cdc2-3w cdc25Delta double mutant, the rate-limiting step leading to mitosis is reaching a critical size. However, the size control of this mutant operates in late G2, which is different from wild-type (WT) cells. This fact suggests that in WT the rate-limiting molecular process during the G2 timer is the Tyr15 dephosphorylation of cdc2, for which the cdc25 phosphatase (together with its back-up, pyp3) is dependent. In the wee1-50 cdc25Delta mutant, the population splits into different clusters, all lacking mitotic size control. This strain maintains size homeostasis by a novel method, which is random movement of the cells from one cluster to another in the successive generations. These cells should normally have a ‘minimal cycle’, a ‘timer’ with short G1 and G2 phases. However, very often the cells abort mitosis, possibly at an early event and return back to early G2, thus lengthening their cycles. The inability of these cells to start anaphase might be caused by the absence of the main mitotic regulators (wee1 and cdc25) and the improper regulation of their back-up copies (mik1 and pyp3, respectively).

Pattern of end growth of the fission yeast Schizosaccharomyces pombe

1990 ◽  
Vol 36 (6) ◽  
pp. 390-394 ◽  
Author(s):  
Hisao Miyata ◽  
Machiko Miyata ◽  
Byron F. Johnson
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Schizosaccharomyces Pombe ◽  
Key Words ◽  
Fission Yeast ◽  
Doubling Time ◽  
Time Lapse ◽  
Critical Value ◽  
Wild Type ◽  
Time Lapse Photomicrography

The patterns of end growth of individual cells of Schizosaccharomyces pombe, wild-type cells (strain 972 h−), cells exposed to 8 mM hydroxyurea, and cdc mutants (cdc11-123 and cdc2-33), were investigated by time-lapse photomicrography. It was reconfirmed that there are three patterns of end growth: cells growing at the old end, at the new end, and at both ends from the beginning of the cell cycle. Cells that initiated growth at the old (new) end increased their growth rate at the new (old) end and became constant in their growth rate at the old (new) end when cells had their growth rate higher than a critical value: 0.08, 0.09, 0.08, and 0.11 μm/min in wild-type cells, cells exposed to hydroxyurea, cdc11-123 cells, and cdc2-33 cells, respectively. The critical value is proportional to the doubling time in length. Key words: extension, growth, fission yeast.

Size control models of Saccharomyces cerevisiae cell proliferation

1982 ◽  
Vol 2 (4) ◽  
pp. 361-368
Author(s):  
A E Wheals
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Proliferation ◽  
Critical Size ◽  
Transition Probability ◽  
Size Control ◽  
Time Lapse ◽  
Growth Conditions ◽  
Yeast Cells ◽  
Cycle Times ◽  
The Individual

By using time-lapse photomicroscopy, the individual cycle times and sizes at bud emergence were measured for a population of saccharomyces cerevisiae cells growing exponentially under balanced growth conditions in a specially constructed filming slide. There was extensive variability in both parameters for daughter and parent cells. The data on 162 pairs of siblings were analyzed for agreement with the predictions of the transition probability hypothesis and the critical-size hypothesis of yeast cell proliferation and also with a model incorporating both of these hypotheses in tandem. None of the models accounted for all of the experimental data, but two models did give good agreement to all of the data. The wobbly tandem model proposes that cells need to attain a critical size, which is very variable, enabling them to enter a start state from which they exit with first order kinetics. The sloppy size control model suggests that cells have an increasing probability per unit time of traversing start as they increase in size, reaching a high plateau value which is less than one. Both models predict that the kinetics of entry into the cell division sequence will strongly depend on variability in birth size and thus will be quite different for daughters and parents of the asymmetrically dividing yeast cells. Mechanisms underlying these models are discussed.

scholarly journals The CDK Pef1 and Protein Phosphatase 4 oppose each other for regulating cohesin binding to fission yeast chromosomes

2019 ◽  
Author(s):  
Adrien Birot ◽  
Marta Tormos-Pérez ◽  
Sabine Vaur ◽  
Amélie Feytout ◽  
Julien Jaegy ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Protein Phosphatase ◽  
Opposite Effect ◽  
Kinase Activity ◽  
Chromosome Structure ◽  
Wild Type ◽  
Human Homologue ◽  
Negative Regulators ◽  
Phosphorylation State ◽  
Fine Tune

ABSTRACTCohesin has essential roles in chromosome structure, segregation and repair. Cohesin binding to chromosomes is catalyzed by the cohesin loader, Mis4 in fission yeast. How cells fine tune cohesin deposition is largely unknown. Here we provide evidence that Mis4 activity is regulated by phosphorylation of its cohesin substrate. A genetic screen for negative regulators of Mis4 yielded a CDK called Pef1, whose closest human homologue is CDK5. Inhibition of Pef1 kinase activity rescued cohesin loader deficiencies. In an otherwise wild-type background, Pef1 ablation stimulated cohesin binding to its regular sites along chromosomes while ablating Protein Phosphatase 4 had the opposite effect. Pef1 and PP4 control the phosphorylation state of the cohesin kleisin Rad21. The CDK phosphorylates Rad21 on Threonine 262. Pef1 ablation, non phosphorylatable Rad21-T262 or mutations within a Rad21 binding domain of Mis4 alleviated the effect of PP4 deficiency. Such a CDK/PP4 based regulation of cohesin loader activity could provide an efficient mechanism for translating cellular cues into a fast and accurate cohesin response.

Sign in / Sign up

Export Citation Format

Share Document