scholarly journals Oscillations in Cdc14 release and sequestration reveal a circuit underlying mitotic exit

2010 ◽  
Vol 190 (2) ◽  
pp. 209-222 ◽  
Author(s):  
Romilde Manzoni ◽  
Francesca Montani ◽  
Clara Visintin ◽  
Fabrice Caudron ◽  
Andrea Ciliberto ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Feedback Loop ◽  
Mitotic Exit ◽  
Centrosome Duplication ◽  
Negative Feedback Loop ◽  
Cyclin Dependent Kinase ◽  
Bud Formation ◽  
Mitotic Exit Network ◽  
Early Anaphase ◽  
Periodic Cycles

In budding yeast, the phosphatase Cdc14 orchestrates progress through anaphase and mitotic exit, thereby resetting the cell cycle for a new round of cell division. Two consecutive pathways, Cdc fourteen early anaphase release (FEAR) and mitotic exit network (MEN), contribute to the progressive activation of Cdc14 by regulating its release from the nucleolus, where it is kept inactive by Cfi1. In this study, we show that Cdc14 activation requires the polo-like kinase Cdc5 together with either Clb–cyclin-dependent kinase (Cdk) or the MEN kinase Dbf2. Once active, Cdc14 triggers a negative feedback loop that, in the presence of stable levels of mitotic cyclins, generates periodic cycles of Cdc14 release and sequestration. Similar phenotypes have been described for yeast bud formation and centrosome duplication. A common theme emerges where events that must happen only once per cycle, although intrinsically capable of oscillations, are limited to one occurrence by the cyclin–Cdk cell cycle engine.

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 Mutual regulation of cyclin-dependent kinase and the mitotic exit network

2010 ◽  
Vol 188 (3) ◽  
pp. 351-368 ◽  
Author(s):  
Cornelia König ◽  
Hiromi Maekawa ◽  
Elmar Schiebel
Keyword(s):  
Spindle Pole Body ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Cyclin Dependent Kinase ◽  
Spatial Regulation ◽  
Daughter Cells ◽  
Pole Body ◽  
Mitotic Exit Network ◽  
Mutual Regulation ◽  
Early Anaphase

The mitotic exit network (MEN) is a spindle pole body (SPB)–associated, GTPase-driven signaling cascade that controls mitotic exit. The inhibitory Bfa1–Bub2 GTPase-activating protein (GAP) only associates with the daughter SPB (dSPB), raising the question as to how the MEN is regulated on the mother SPB (mSPB). Here, we show mutual regulation of cyclin-dependent kinase 1 (Cdk1) and the MEN. In early anaphase Cdk1 becomes recruited to the mSPB depending on the activity of the MEN kinase Cdc15. Conversely, Cdk1 negatively regulates binding of Cdc15 to the mSPB. In addition, Cdk1 phosphorylates the Mob1 protein to inhibit the activity of Dbf2–Mob1 kinase that regulates Cdc14 phosphatase. Our data revise the understanding of the spatial regulation of the MEN. Although MEN activity in the daughter cells is controlled by Bfa1–Bub2, Cdk1 inhibits MEN activity at the mSPB. Consistent with this model, only triple mutants that lack BUB2 and the Cdk1 phosphorylation sites in Mob1 and Cdc15 show mitotic exit defects.

scholarly journals DNA Damage Checkpoints Inhibit Mitotic Exit by Two Different Mechanisms

2007 ◽  
Vol 27 (14) ◽  
pp. 5067-5078 ◽  
Author(s):  
Fengshan Liang ◽  
Yanchang Wang
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Progression ◽  
Budding Yeast ◽  
Mitotic Exit ◽  
Yeast Cells ◽  
Cyclin Dependent Kinase ◽  
Cycle Progression ◽  
Dna Damage Checkpoints ◽  
Early Anaphase

ABSTRACT Cyclin-dependent kinase (CDK) governs cell cycle progression, and its kinase activity fluctuates during the cell cycle. Mitotic exit pathways are responsible for the inactivation of CDK after chromosome segregation by promoting the release of a nucleolus-sequestered phosphatase, Cdc14, which antagonizes CDK. In the budding yeast Saccharomyces cerevisiae, mitotic exit is controlled by the FEAR (for “Cdc-fourteen early anaphase release”) and mitotic exit network (MEN) pathways. In response to DNA damage, two branches of the DNA damage checkpoint, Chk1 and Rad53, are activated in budding yeast to prevent anaphase entry and mitotic exit, allowing cells more time to repair damaged DNA. Here we present evidence indicating that yeast cells negatively regulate mitotic exit through two distinct pathways in response to DNA damage. Rad53 prevents mitotic exit by inhibiting the MEN pathway, whereas the Chk1 pathway prevents FEAR pathway-dependent Cdc14 release in the presence of DNA damage. In contrast to previous data, the Rad53 pathway negatively regulates MEN independently of Cdc5, a Polo-like kinase essential for mitotic exit. Instead, a defective Rad53 pathway alleviates the inhibition of MEN by Bfa1.

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 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 Putting the Brake on FEAR: Tof2 Promotes the Biphasic Release of Cdc14 Phosphatase during Mitotic Exit

2009 ◽  
Vol 20 (1) ◽  
pp. 245-255 ◽  
Author(s):  
William G. Waples ◽  
Charly Chahwan ◽  
Marta Ciechonska ◽  
Brigitte D. Lavoie
Keyword(s):  
Chromosome Segregation ◽  
Genetic Data ◽  
Mitotic Exit ◽  
Genetic Interactions ◽  
Genetic Screens ◽  
Rdna Array ◽  
Mitotic Exit Network ◽  
M Phase ◽  
Early Anaphase ◽  
Biphasic Release

The completion of chromosome segregation during anaphase requires the hypercondensation of the ∼1-Mb rDNA array, a reaction dependent on condensin and Cdc14 phosphatase. Using systematic genetic screens, we identified 29 novel genetic interactions with budding yeast condensin. Of these, FOB1, CSM1, LRS4, and TOF2 were required for the mitotic condensation of the tandem rDNA array localized on chromosome XII. Interestingly, whereas Fob1 and the monopolin subunits Csm1 and Lrs4 function in rDNA condensation throughout M phase, Tof2 was only required during anaphase. We show that Tof2, which shares homology with the Cdc14 inhibitor Net1/Cfi1, interacts with Cdc14 phosphatase and its deletion suppresses defects in mitotic exit network (MEN) components. Consistent with these genetic data, the onset of Cdc14 release from the nucleolus was similar in TOF2 and tof2Δ cells; however, the magnitude of the release was dramatically increased in the absence of Tof2, even when the MEN pathway was compromised. These data support a model whereby Tof2 coordinates the biphasic release of Cdc14 during anaphase by restraining a population of Cdc14 in the nucleolus after activation of the Cdc14 early anaphase release (FEAR) network, for subsequent release by the MEN.

scholarly journals A Novel Hyperactive Nud1 Mitotic Exit Network Scaffold Causes Spindle Position Checkpoint Bypass in Budding Yeast

Cells ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 46
Author(s):  
Michael Vannini ◽  
Victoria R. Mingione ◽  
Ashleigh Meyer ◽  
Courtney Sniffen ◽  
Jenna Whalen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Signal Transduction Pathway ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Independent Manner ◽  
Spindle Pole Bodies ◽  
Mitotic Exit Network ◽  
Cell Cycle Transition ◽  
Spindle Position

Mitotic exit is a critical cell cycle transition that requires the careful coordination of nuclear positioning and cyclin B destruction in budding yeast for the maintenance of genome integrity. The mitotic exit network (MEN) is a Ras-like signal transduction pathway that promotes this process during anaphase. A crucial step in MEN activation occurs when the Dbf2-Mob1 protein kinase complex associates with the Nud1 scaffold protein at the yeast spindle pole bodies (SPBs; centrosome equivalents) and thereby becomes activated. This requires prior priming phosphorylation of Nud1 by Cdc15 at SPBs. Cdc15 activation, in turn, requires both the Tem1 GTPase and the Polo kinase Cdc5, but how Cdc15 associates with SPBs is not well understood. We have identified a hyperactive allele of NUD1, nud1-A308T, that recruits Cdc15 to SPBs in all stages of the cell cycle in a CDC5-independent manner. This allele leads to early recruitment of Dbf2-Mob1 during metaphase and requires known Cdc15 phospho-sites on Nud1. The presence of nud1-A308T leads to loss of coupling between nuclear position and mitotic exit in cells with mispositioned spindles. Our findings highlight the importance of scaffold regulation in signaling pathways to prevent improper activation.

Systems-level feedback in cell-cycle control

2010 ◽  
Vol 38 (5) ◽  
pp. 1242-1246 ◽  
Author(s):  
Béla Novák ◽  
P.K. Vinod ◽  
Paula Freire ◽  
Orsolya Kapuy
Keyword(s):  
Cell Cycle ◽  
Feedback Loop ◽  
Cell Cycle Control ◽  
Double Negative ◽  
Cyclin Dependent Kinase ◽  
Successful Completion ◽  
Cell Cycles ◽  
Underlying Network ◽  
Oscillatory Mechanism ◽  
Negative Feedbacks

Alternation of chromosome replication and segregation is essential for successful completion of the cell cycle and it requires an oscillation of Cdk1 (cyclin-dependent kinase 1)–CycB (cyclin B) activity. In the present review, we illustrate the essential features of checkpoint controlled and uncontrolled cell-cycle oscillations by using mechanical metaphors. Despite variations in the molecular details of the oscillatory mechanism, the underlying network motifs responsible for the oscillations are always well-conserved. The checkpoint-controlled cell cycles are always driven by a negative-feedback loop amplified by double-negative feedbacks (antagonism).

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