scholarly journals Meiotic nuclear divisions in budding yeast require PP2ACdc55-mediated antagonism of Net1 phosphorylation by Cdk

2011 ◽  
Vol 193 (7) ◽  
pp. 1157-1166 ◽  
Author(s):  
Gary W. Kerr ◽  
Sourav Sarkar ◽  
Katherine L. Tibbles ◽  
Mark Petronczki ◽  
Jonathan B.A. Millar ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Deoxyribonucleic Acid ◽  
Nuclear Division ◽  
Mutant Form ◽  
Phosphorylation Sites ◽  
Cyclin Dependent Kinase ◽  
Dominant Mutant ◽  
Early Anaphase ◽  
Cdk Phosphorylation ◽  
Meiosis I

During meiosis, one round of deoxyribonucleic acid replication is followed by two rounds of nuclear division. In Saccharomyces cerevisiae, activation of the Cdc14 early anaphase release (FEAR) network is required for exit from meiosis I but does not lead to the activation of origins of replication. The precise mechanism of how FEAR regulates meiosis is not understood. In this paper, we report that premature activation of FEAR during meiosis caused by loss of protein phosphatase PP2ACdc55 activity blocks bipolar spindle assembly and nuclear divisions. In cdc55 meiotic null (cdc55-mn) cells, the cyclin-dependent kinase (Cdk)–counteracting phosphatase Cdc14 was released prematurely from the nucleolus concomitant with hyperphosphorylation of its nucleolar anchor protein Net1. Crucially, a mutant form of Net1 that lacks six Cdk phosphorylation sites rescued the meiotic defect of cdc55-mn cells. Expression of a dominant mutant allele of CDC14 mimicked the cdc55-mn phenotype. We propose that phosphoregulation of Net1 by PP2ACdc55 is essential for preventing precocious exit from meiosis I.

scholarly journals Cdc55 coordinates spindle assembly and chromosome disjunction during meiosis

2011 ◽  
Vol 193 (7) ◽  
pp. 1213-1228 ◽  
Author(s):  
Farid Bizzari ◽  
Adele L. Marston
Keyword(s):  
Protein Phosphatase ◽  
Deoxyribonucleic Acid ◽  
Nuclear Division ◽  
Spindle Assembly ◽  
Regulatory Subunit ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Phosphatase 2A ◽  
Meiosis I ◽  
Sequential Assembly

During meiosis, two consecutive nuclear divisions follow a single round of deoxyribonucleic acid replication. In meiosis I, homologues are segregated, whereas in meiosis II, sister chromatids are segregated. This requires that the sequential assembly and dissolution of specialized chromosomal factors are coordinated with two rounds of spindle assembly and disassembly. How these events are coupled is unknown. In this paper, we show, in budding yeast, that the protein phosphatase 2A regulatory subunit Cdc55 couples the loss of linkages between chromosomes with nuclear division by restraining two other phosphatases, Cdc14 and PP2ARts1. Cdc55 maintains Cdc14 sequestration in the nucleolus during early meiosis, and this is essential for the assembly of the meiosis I spindle but not for chromosomes to separate. Cdc55 also limits the formation of PP2A holocomplexes containing the alternative regulatory subunit Rts1, which is crucial for the timely dissolution of sister chromatid cohesion. Therefore, Cdc55 orders passage through the meiotic divisions by ensuring a balance of phosphatases.

Neuronal Cyclin-Dependent Kinase-5 Phosphorylation Sites in Neurofilament Protein (NF-H) Are Dephosphorylated by Protein Phosphatase 2A

2002 ◽  
Vol 64 (6) ◽  
pp. 2681-2690 ◽  
Author(s):  
Veeranna ◽  
K. T. Shetty ◽  
W. T. Link ◽  
H. Jaffe ◽  
J. Wang ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Phosphorylation Sites ◽  
Cyclin Dependent Kinase ◽  
Neurofilament Protein ◽  
Phosphatase 2A ◽  
Cyclin Dependent Kinase 5

scholarly journals Roles of the CDK Phosphorylation Sites of Yeast Cdc6 in Chromatin Binding and Rereplication

2007 ◽  
Vol 18 (4) ◽  
pp. 1324-1336 ◽  
Author(s):  
Sangeet Honey ◽  
Bruce Futcher
Keyword(s):  
Nuclear Import ◽  
Replication Initiation ◽  
Phosphorylation Sites ◽  
Cyclin Dependent Kinase ◽  
Chromatin Binding ◽  
Wild Type ◽  
Mcm Proteins ◽  
Cdk Phosphorylation ◽  
Replication Initiation Proteins ◽  
Dominant Lethality

The Saccharomyces cerevisiae Cdc6 protein is crucial for DNA replication. In the absence of cyclin-dependent kinase (CDK) activity, Cdc6 binds to replication origins, and loads Mcm proteins. In the presence of CDK activity, Cdc6 does not bind to origins, and this helps prevent rereplication. CDK activity affects Cdc6 function by multiple mechanisms: CDK activity affects transcription of CDC6, degradation of Cdc6, nuclear import of Cdc6, and binding of Cdc6 to Clb2. Here we examine some of these mechanisms individually. We find that when Cdc6 is forced into the nucleus during late G1 or S, it will not substantially reload onto chromatin no matter whether its CDK sites are present or not. In contrast, at a G2/M nocodazole arrest, Cdc6 will reload onto chromatin if and only if its CDK sites have been removed. Trace amounts of nonphosphorylatable Cdc6 are dominant lethal in strains bearing nonphosphorylatable Orc2 and Orc6, apparently because of rereplication. This synthetic dominant lethality occurs even in strains with wild-type MCM genes. Nonphosphorylatable Cdc6, or Orc2 and Orc6, sensitize cells to rereplication caused by overexpression of various replication initiation proteins such as Dpb11 and Sld2.

scholarly journals Saccharomyces cerevisiae Ime2 phosphorylates Sic1 at multiple PXS/T sites but is insufficient to trigger Sic1 degradation

2006 ◽  
Vol 399 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Chantelle Sedgwick ◽  
Matthew Rawluk ◽  
James Decesare ◽  
Sheetal Raithatha ◽  
James Wohlschlegel ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Phase Boundary ◽  
S Phase ◽  
Phosphorylation Sites ◽  
Cyclin Dependent Kinase ◽  
Proliferating Cells ◽  
Initiation Of Dna Replication ◽  
Cdk Phosphorylation

The initiation of DNA replication in Saccharomyces cerevisiae depends upon the destruction of the Clb–Cdc28 inhibitor Sic1. In proliferating cells Cln–Cdc28 complexes phosphorylate Sic1, which stimulates binding of Sic1 to SCFCdc4 and triggers its proteosome mediated destruction. During sporulation cyclins are not expressed, yet Sic1 is still destroyed at the G1-/S-phase boundary. The Cdk (cyclin dependent kinase) sites are also required for Sic1 destruction during sporulation. Sic1 that is devoid of Cdk phosphorylation sites displays increased stability and decreased phosphorylation in vivo. In addition, we found that Sic1 was modified by ubiquitin in sporulating cells and that SCFCdc4 was required for this modification. The meiosis-specific kinase Ime2 has been proposed to promote Sic1 destruction by phosphorylating Sic1 in sporulating cells. We found that Ime2 phosphorylates Sic1 at multiple sites in vitro. However, only a subset of these sites corresponds to Cdk sites. The identification of multiple sites phosphorylated by Ime2 has allowed us to propose a motif for phosphorylation by Ime2 (PXS/T) where serine or threonine acts as a phospho-acceptor. Although Ime2 phosphorylates Sic1 at multiple sites in vitro, the modified Sic1 fails to bind to SCFCdc4. In addition, the expression of Ime2 in G1 arrested haploid cells does not promote the destruction of Sic1. These data support a model where Ime2 is necessary but not sufficient to promote Sic1 destruction during sporulation.

scholarly journals Phosphorylation of Sic1, a Cyclin-dependent Kinase (Cdk) Inhibitor, by Cdk Including Pho85 Kinase Is Required for Its Prompt Degradation

1998 ◽  
Vol 9 (9) ◽  
pp. 2393-2405 ◽  
Author(s):  
Masafumi Nishizawa ◽  
Masaoki Kawasumi ◽  
Marie Fujino ◽  
Akio Toh-e
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Cdk Inhibitor ◽  
Phosphorylation Sites ◽  
Cyclin Dependent Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cdk Phosphorylation ◽  
Cdc28 Kinase

In the yeast Saccharomyces cerevisiae, Sic1, an inhibitor of Clb-Cdc28 kinases, must be phosphorylated and degraded in G1for cells to initiate DNA replication, and Cln-Cdc28 kinase appears to be primarily responsible for phosphorylation of Sic1. The Pho85 kinase is a yeast cyclin-dependent kinase (Cdk), which is not essential for cell growth unless both CLN1 andCLN2 are absent. We demonstrate that Pho85, when complexed with Pcl1, a G1cyclin homologue, can phosphorylate Sic1 in vitro, and that Sic1 appears to be more stable inpho85Δ cells. Three consensus Cdk phosphorylation sites present in Sic1 are phosphorylated in vivo, and two of them are required for prompt degradation of the inhibitor. Pho85 and other G1Cdks appear to phosphorylate Sic1 at different sites in vivo. Thus at least two distinct Cdks can participate in phosphorylation of Sic1 and may therefore regulate progression through G1.

scholarly journals The Molecular Function of the Yeast Polo-like Kinase Cdc5 in Cdc14 Release during Early Anaphase

2009 ◽  
Vol 20 (16) ◽  
pp. 3671-3679 ◽  
Author(s):  
Fengshan Liang ◽  
Fengzhi Jin ◽  
Hong Liu ◽  
Yanchang Wang
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Phosphatase ◽  
Budding Yeast ◽  
Molecular Function ◽  
Cyclin Dependent Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Protein Levels ◽  
Early Anaphase ◽  
Show Evidence ◽  
Mitotic Cyclin

In the budding yeast Saccharomyces cerevisiae , Cdc14 is sequestered within the nucleolus before anaphase entry through its association with Net1/Cfi1, a nucleolar protein. Protein phosphatase PP2ACdc55 dephosphorylates Net1 and keeps it as a hypophosphorylated form before anaphase. Activation of the Cdc fourteen early anaphase release (FEAR) pathway after anaphase entry induces a brief Cdc14 release from the nucleolus. Some of the components in the FEAR pathway, including Esp1, Slk19, and Spo12, inactivate PP2ACdc55, allowing the phosphorylation of Net1 by mitotic cyclin-dependent kinase (Cdk) (Clb2-Cdk1). However, the function of another FEAR component, the Polo-like kinase Cdc5, remains elusive. Here, we show evidence indicating that Cdc5 promotes Cdc14 release primarily by stimulating the degradation of Swe1, the inhibitory kinase for mitotic Cdk. First, we found that deletion of SWE1 partially suppresses the FEAR defects in cdc5 mutants. In contrast, high levels of Swe1 impair FEAR activation. We also demonstrated that the accumulation of Swe1 in cdc5 mutants is responsible for the decreased Net1 phosphorylation. Therefore, we conclude that the down-regulation of Swe1 protein levels by Cdc5 promotes FEAR activation by relieving the inhibition on Clb2-Cdk1, the kinase for Net1 protein.

scholarly journals Dual-mode regulation of the APC/C by CDK1 and MAPK controls meiosis I progression and fidelity

2014 ◽  
Vol 204 (6) ◽  
pp. 891-900 ◽  
Author(s):  
Ibtissem Nabti ◽  
Petros Marangos ◽  
Jenny Bormann ◽  
Nobuaki R. Kudo ◽  
John Carroll
Keyword(s):  
Protein Kinase ◽  
Spindle Assembly Checkpoint ◽  
Mitogen Activated Protein Kinase ◽  
Cyclin Dependent Kinase ◽  
Anaphase Promoting Complex ◽  
Female Meiosis ◽  
Dual Mode ◽  
Mitogen Activated Protein ◽  
Meiosis I

Female meiosis is driven by the activities of two major kinases, cyclin-dependent kinase 1 (Cdk1) and mitogen-activated protein kinase (MAPK). To date, the role of MAPK in control of meiosis is thought to be restricted to maintaining metaphase II arrest through stabilizing Cdk1 activity. In this paper, we find that MAPK and Cdk1 play compensatory roles to suppress the anaphase-promoting complex/cyclosome (APC/C) activity early in prometaphase, thereby allowing accumulation of APC/C substrates essential for meiosis I. Furthermore, inhibition of MAPK around the onset of APC/C activity at the transition from meiosis I to meiosis II led to accelerated completion of meiosis I and an increase in aneuploidy at metaphase II. These effects appear to be mediated via a Cdk1/MAPK-dependent stabilization of the spindle assembly checkpoint, which when inhibited leads to increased APC/C activity. These findings demonstrate new roles for MAPK in the regulation of meiosis in mammalian oocytes.

scholarly journals The prognostic value of Cyclin-Dependent Kinase 5 and Protein Phosphatase 2A in Gastric Cancer

2018 ◽  
Vol 9 (23) ◽  
pp. 4404-4412 ◽  
Author(s):  
Jian-Xian Lin ◽  
Xin-Sheng Xie ◽  
Xiong-Feng Weng ◽  
Chao-Hui Zheng ◽  
Jian-Wei Xie ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Protein Phosphatase ◽  
Prognostic Value ◽  
Protein Phosphatase 2A ◽  
Cyclin Dependent Kinase ◽  
Phosphatase 2A ◽  
Cyclin Dependent Kinase 5

scholarly journals Protein Phosphatase 2A B'α and B'β Protect Centromeric Cohesion during Meiosis I

2019 ◽  
Vol 179 (4) ◽  
pp. 1556-1568 ◽  
Author(s):  
Yu-Lan Zhang ◽  
He Zhang ◽  
Ying-Jie Gao ◽  
Lin-Lin Yan ◽  
Xin-Yu Yu ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Phosphatase 2A ◽  
Meiosis I
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