scholarly journals Degradation of the Mitotic Cyclin Clb3 Is not Required for Mitotic Exit but Is Necessary for G1 Cyclin Control of the Succeeding Cell Cycle

Genetics ◽  
2016 ◽  
Vol 204 (4) ◽  
pp. 1479-1494 ◽  
Author(s):  
Kresti Pecani ◽  
Frederick R. Cross
Keyword(s):  
Cell Cycle ◽  
Mitotic Exit ◽  
G1 Cyclin ◽  
Mitotic Cyclin

scholarly journals Genetic and Biochemical Evaluation of the Importance of Cdc6 in Regulating Mitotic Exit

2003 ◽  
Vol 14 (11) ◽  
pp. 4592-4604 ◽  
Author(s):  
Vincent Archambault ◽  
Caihong X. Li ◽  
Alan J. Tackett ◽  
Ralph Wäsch ◽  
Brian T. Chait ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Mitotic Exit ◽  
Terminal Region ◽  
Cyclin Dependent Kinase ◽  
Replication Control ◽  
Mitotic Cyclin ◽  
Biochemical Evaluation ◽  
Inhibitory Domain ◽  
Late Mitosis ◽  
Control Protein

We evaluated the hypothesis that the N-terminal region of the replication control protein Cdc6 acts as an inhibitor of cyclin-dependent kinase (Cdk) activity, promoting mitotic exit. Cdc6 accumulation is restricted to the period from mid-cell cycle until the succeeding G1, due to proteolytic control that requires the Cdc6 N-terminal region. During late mitosis, Cdc6 is present at levels comparable with Sic1 and binds specifically to the mitotic cyclin Clb2. Moderate overexpression of Cdc6 promotes viability of CLB2Δdb strains, which otherwise arrest at mitotic exit, and rescue is dependent on the N-terminal putative Cdk-inhibitory domain. These observations support the potential for Cdc6 to inhibit Clb2-Cdk, thus promoting mitotic exit. Consistent with this idea, we observed a cytokinesis defect in cdh1Δ sic1Δ cdc6Δ2–49 triple mutants. However, we were able to construct viable strains, in three different backgrounds, containing neither SIC1 nor the Cdc6 Cdk-inhibitory domain, in contradiction to previous work. We conclude, therefore, that although both Cdc6 and Sic1 have the potential to facilitate mitotic exit by inhibiting Clb2-Cdk, mitotic exit nevertheless does not require any identified stoichiometric inhibitor of Cdk activity.

scholarly journals Separase cooperates with Zds1 and Zds2 to activate Cdc14 phosphatase in early anaphase

2008 ◽  
Vol 182 (5) ◽  
pp. 873-883 ◽  
Author(s):  
Ethel Queralt ◽  
Frank Uhlmann
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Mitotic Exit ◽  
Interacting Proteins ◽  
Cyclin Dependent Kinase ◽  
Down Regulation ◽  
Anaphase Onset ◽  
Early Anaphase ◽  
Key Enzyme ◽  
Mitotic Cyclin

Completion of mitotic exit and cytokinesis requires the inactivation of mitotic cyclin-dependent kinase (Cdk) activity. A key enzyme that counteracts Cdk during budding yeast mitotic exit is the Cdc14 phosphatase. Cdc14 is inactive for much of the cell cycle, sequestered by its inhibitor Net1 in the nucleolus. At anaphase onset, separase-dependent down-regulation of PP2ACdc55 allows phosphorylation of Net1 and consequent Cdc14 release. How separase causes PP2ACdc55 down-regulation is not known. Here, we show that two Cdc55-interacting proteins, Zds1 and Zds2, contribute to timely Cdc14 activation during mitotic exit. Zds1 and Zds2 are required downstream of separase to facilitate nucleolar Cdc14 release. Ectopic Zds1 expression in turn is sufficient to down-regulate PP2ACdc55 and promote Net1 phosphorylation. These findings identify Zds1 and Zds2 as new components of the mitotic exit machinery, involved in activation of the Cdc14 phosphatase at anaphase onset. Our results suggest that these proteins may act as separase-regulated PP2ACdc55 inhibitors.

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 Disruption of Centrosome Structure, Chromosome Segregation, and Cytokinesis by Misexpression of Human Cdc14A Phosphatase

2002 ◽  
Vol 13 (7) ◽  
pp. 2289-2300 ◽  
Author(s):  
Brett K. Kaiser ◽  
Zachary A. Zimmerman ◽  
Harry Charbonneau ◽  
Peter K. Jackson
Keyword(s):  
Cell Cycle ◽  
Phosphatase Activity ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Genomic Stability ◽  
Mitotic Exit ◽  
Protein Abundance ◽  
Cyclin Dependent Kinase ◽  
Chromosome Partitioning

In budding yeast, the Cdc14p phosphatase activates mitotic exit by dephosphorylation of specific cyclin-dependent kinase (Cdk) substrates and seems to be regulated by sequestration in the nucleolus until its release in mitosis. Herein, we have analyzed the two human homologs of Cdc14p, hCdc14A and hCdc14B. We demonstrate that the human Cdc14A phosphatase is selective for Cdk substrates in vitro and that although the protein abundance and intrinsic phosphatase activity of hCdc14A and B vary modestly during the cell cycle, their localization is cell cycle regulated. hCdc14A dynamically localizes to interphase but not mitotic centrosomes, and hCdc14B localizes to the interphase nucleolus. These distinct patterns of localization suggest that each isoform of human Cdc14 likely regulates separate cell cycle events. In addition, hCdc14A overexpression induces the loss of the pericentriolar markers pericentrin and γ-tubulin from centrosomes. Overproduction of hCdc14A also causes mitotic spindle and chromosome segregation defects, defective karyokinesis, and a failure to complete cytokinesis. Thus, the hCdc14A phosphatase appears to play a role in the regulation of the centrosome cycle, mitosis, and cytokinesis, thereby influencing chromosome partitioning and genomic stability in human cells.

scholarly journals Quantitative Characterization of a Mitotic Cyclin Threshold Regulating Exit from Mitosis

2005 ◽  
Vol 16 (5) ◽  
pp. 2129-2138 ◽  
Author(s):  
Frederick R. Cross ◽  
Lea Schroeder ◽  
Martin Kruse ◽  
Katherine C. Chen
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Cell Cycle Control ◽  
Predictive Ability ◽  
Eukaryotic Cell ◽  
Model Predictions ◽  
Mitotic Cyclin ◽  
Constitutive Overexpression

Regulation of cyclin abundance is central to eukaryotic cell cycle control. Strong overexpression of mitotic cyclins is known to lock the system in mitosis, but the quantitative behavior of the control system as this threshold is approached has only been characterized in the in vitro Xenopus extract system. Here, we quantitate the threshold for mitotic block in budding yeast caused by constitutive overexpression of the mitotic cyclin Clb2. Near this threshold, the system displays marked loss of robustness, in that loss or even heterozygosity for some regulators becomes deleterious or lethal, even though complete loss of these regulators is tolerated at normal cyclin expression levels. Recently, we presented a quantitative kinetic model of the budding yeast cell cycle. Here, we use this model to generate biochemical predictions for Clb2 levels, asynchronous as well as through the cell cycle, as the Clb2 overexpression threshold is approached. The model predictions compare well with biochemical data, even though no data of this type were available during model generation. The loss of robustness of the Clb2 overexpressing system is also predicted by the model. These results provide strong confirmation of the model's predictive ability.

scholarly journals A 62-kD protein required for mitotic progression is associated with the mitotic apparatus during M-phase and with the nucleus during interphase.

1992 ◽  
Vol 119 (4) ◽  
pp. 843-854 ◽  
Author(s):  
J A Johnston ◽  
R D Sloboda
Keyword(s):  
Cell Cycle ◽  
Nuclear Envelope ◽  
Cellular Protein ◽  
Immunogold Electron Microscopy ◽  
Mitotic Apparatus ◽  
Surf Clam ◽  
Calcium Calmodulin Dependent ◽  
Protein Pool ◽  
Mitotic Cyclin

A protein of 62 kD is a substrate of a calcium/calmodulin-dependent protein kinase, and both proteins copurify with isolated mitotic apparatuses (Dinsmore, J. H., and R. D. Sloboda. 1988. Cell. 53:769-780). Phosphorylation of the 62-kD protein increases after fertilization; maximum incorporation of phosphate occurs during late metaphase and anaphase and correlates directly with microtubule disassembly as determined by in vitro experiments with isolated mitotic apparatuses. Because 62-kD protein phosphorylation occurs in a pattern similar to the accumulation of the mitotic cyclin proteins, experiments were performed to determine the relationship between cyclin and the 62-kD protein. Continuous labeling of marine embryos with [35S]methionine, as well as immunoblots of marine embryo proteins using specific antibodies, were used to identify both cyclin and the 62-kD protein. These results clearly demonstrate that the 62-kD protein is distinct from cyclin and, unlike cyclin, is a constant member of the cellular protein pool during the first two cell cycles in sea urchin and surf clam embryos. Similar results were obtained using immunofluorescence microscopy of intact eggs and embryos. In addition, immunogold electron microscopy reveals that the 62-kD protein associates with the microtubules of the mitotic apparatus in dividing cells. Interestingly, the protein changes its subcellular distribution with respect to microtubules during the cell cycle. Specifically, during mitosis the 62-kD protein associates with the mitotic apparatus; before nuclear envelope breakdown, however, the 62-kD protein is confined to the nucleus. After anaphase, the 62-kD protein returns to the nucleus, where it resides until nuclear envelope disassembly of the next cell cycle.

scholarly journals PP2ARts1 is a master regulator of pathways that control cell size

2014 ◽  
Vol 204 (3) ◽  
pp. 359-376 ◽  
Author(s):  
Jessica Zapata ◽  
Noah Dephoure ◽  
Tracy MacDonough ◽  
Yaxin Yu ◽  
Emily J. Parnell ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Cell Size ◽  
Control Cell ◽  
Size Control ◽  
Regulatory Subunit ◽  
Delay Cell ◽  
Cell Cycle Entry ◽  
G1 Cyclin

Cell size checkpoints ensure that passage through G1 and mitosis occurs only when sufficient growth has occurred. The mechanisms by which these checkpoints work are largely unknown. PP2A associated with the Rts1 regulatory subunit (PP2ARts1) is required for cell size control in budding yeast, but the relevant targets are unknown. In this paper, we used quantitative proteome-wide mass spectrometry to identify proteins controlled by PP2ARts1. This revealed that PP2ARts1 controls the two key checkpoint pathways thought to regulate the cell cycle in response to cell growth. To investigate the role of PP2ARts1 in these pathways, we focused on the Ace2 transcription factor, which is thought to delay cell cycle entry by repressing transcription of the G1 cyclin CLN3. Diverse experiments suggest that PP2ARts1 promotes cell cycle entry by inhibiting the repressor functions of Ace2. We hypothesize that control of Ace2 by PP2ARts1 plays a role in mechanisms that link G1 cyclin accumulation to cell growth.

Proteomic Analysis of Acute Promyelocytic Leukemia Reveals That PML-RARalpha Induces Cell Cycle Progression and Mitotic Exit by Increased Expression and Decreased Ser63 Phosphorylation of OP18.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2028-2028
Author(s):  
A. PeerZada ◽  
M. Geletu ◽  
J. Pullikan ◽  
V. Reddy ◽  
W. Hiddemann ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Acute Promyelocytic Leukemia ◽  
Cell Cycle Progression ◽  
Promyelocytic Leukemia ◽  
Mitotic Exit ◽  
Cycle Progression ◽  
2D Gel ◽  
First Time ◽  
Common Cell

Abstract We applied a mass spectrometry based approach to explore the proteins differentially regulated by PML-RARalpha, a translocation characteristic of acute promyelocytic leukemia (APL). Bioinformatic pathway analysis placed the 46 identified PML-RARalpha regulated proteins into three major networks, OP18-MAPK1, HSP-STAT3 and CCT-MYC. Using this approach, we were able to generate a common cell cycle network of the proteins in these pathways. Further analysis indicated that mRNA expression of OP18, which belonged to this network, was elevated in APL patients and the increased OP18 protein expression upon PML-RARalpha induction was overcome by retinoic acid treatment. Here we also report, for the first time a novel role of PML-RARalpha in cell cycle progression and mitotic exit. RNA interference experiments revealed that siRNA against OP18 overcomes PML-RARalpha effects on cell cycle progression. In addition to increased OP18 expression by PML-RARalpha, 2D gel electrophoresis revealed an isomer of OP18, subsequently confirmed by 2D-western as ser63 phosphomer to be downregulated by PML-RARalpha. Based on these findings, point mutation experiments indicated that decreased phosphorylation of ser63 in OP18 is important for PML-RARalpha mediated cell cycle and mitotic index effects since a constitutive phosphorylated mutant (ser63/asp) of OP18 overcame the PML-RARalpha effects in U9/PR cells, NB4 and APL patients. In summary, our results demonstrate that the effect of PML-RARalpha on cell cycle progression and mitotic exit is via two mechanisms: increasing the expression of OP18 and decreasing the phosphorylation of OP18 at ser63.

scholarly journals The D-type alfalfa cyclin gene cycMs4 complements G1 cyclin-deficient yeast and is induced in the G1 phase of the cell cycle.

1995 ◽  
Vol 7 (11) ◽  
pp. 1847-1857 ◽  
Author(s):  
M Dahl ◽  
I Meskiene ◽  
L Bögre ◽  
D T Ha ◽  
I Swoboda ◽  
...  
Keyword(s):  
Cell Cycle ◽  
G1 Phase ◽  
G1 Cyclin ◽  
Cyclin Gene
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