Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Spo13/MEIKIN ensures a two-division meiosis by preventing the activation of APC/CAma1 at meiosis I

ABSTRACT: Genome haploidization at meiosis depends on two consecutive nuclear divisions, which are controlled by an oscillatory system consisting of Cdk1-cyclin B and the APC/C bound to the Cdc20 activator. How the oscillator generates exactly two divisions has been unclear. We have studied this question in yeast where exit from meiosis involves accumulation of the APC/C activator Ama1 at meiosis II. We show that inactivation of the meiosis I-specific protein Spo13/MEIKIN results in a single-division meiosis due to premature activation of APC/CAma1. In the wild-type, Spo13 bound to the polo-like kinase Cdc5 prevents Ama1 synthesis at meiosis I by stabilizing the translational repressor Rim4. In addition, Cdc5-Spo13 inhibits the activity of Ama1 by converting the B-type cyclin Clb1 from a substrate to an inhibitor of Ama1. Cdc20-dependent degradation of Spo13 at anaphase I unleashes a feedback loop that increases Ama1’s synthesis and activity, leading to irreversible exit from meiosis at the second division. Thus, by repressing the exit machinery at meiosis I, Cdc5-Spo13 ensures that cells undergo two divisions to produce haploid gametes.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Saccharomyces Cerevisiae (baker's Yeast)

SUBMITTER: Barbara Steigenberger

LAB HEAD: Dr. Wolfgang Zachariae

PROVIDER: PXD044597 | Pride | 2023-09-03

REPOSITORIES: Pride

ACCESS DATA

Json Xml

Similar Datasets

Coupling of Cdc20 inhibition and activation by BubR1

Project description:Tight regulation of the APC/C-Cdc20 ubiquitin ligase that targets Cyclin B1 for degradation is important for mitotic fidelity. The spindle assembly checkpoint (SAC) inhibits Cdc20 through the mitotic checkpoint complex (MCC). In addition, phosphorylation of Cdc20 by Cyclin B1-Cdk1 independently inhibits APC/C-Cdc20 activation. This creates a conundrum for how Cdc20 gets activated prior to Cyclin B1 degradation. Here we show that the MCC component BubR1 harbours both Cdc20 inhibition and activation activities, allowing for cross-talk between the two Cdc20 inhibition pathways. Specifically BubR1 acts as a substrate specifier for PP2A-B56 to enable efficient Cdc20 dephosphorylation in the MCC. A mutant Cdc20 mimicking the dephosphorylated state escapes a mitotic checkpoint arrest arguing that restricting Cdc20 dephosphorylation to the MCC is important. Collectively our work reveals how Cdc20 can be dephosphorylated in the presence of Cyclin B1-Cdk1 activity without causing premature anaphase onset.

2021-02-18 | MSV000086910 | MassIVE

Paradoxical mitotic exit induced by a small molecule inhibitor of APC/C Cdc20

Project description:The Anaphase Promoting Complex/Cyclosome (APC/C) is a mega-dalton ubiquitin ligase that initiates mitotic exit by targeting substrates for degradation. The APC/C is activated by Cdc20, which acts as a substrate receptor, and is inhibited by the mitotic checkpoint complex (MCC), which delays mitotic exit when the spindle assembly checkpoint (SAC) is activated. We previously identified apcin, a small molecule ligand of Cdc20, as an inhibitor of APC/CCdc20. Surprisingly, we found that apcin paradoxically accelerates substrate degradation and promotes mitotic exit in cells with high SAC activity. Biochemical studies indicate that apcin cooperates with p31comet to relieve MCC-dependent inhibition of APC/C. Apcin’s behavior as an antagonist of Cdc20 can thus result in either net inhibition of APC/C, delaying mitotic exit when SAC activity is slow, or net activation of APC/C, promoting mitotic exit when SAC activity is high. Genetic experiments suggest that the dual behaviors of apcin arise from targeting a common binding site in Cdc20 that is required for both substrate ubiquitination as well as efficient APC/C inhibition by MCC. We therefore establish a new mechanism through which a small molecule, by targeting a single site on a dynamic protein interface, can lead to opposing biological effects depending on the regulatory context.

2020-01-07 | PXD013786 | Pride

A complex role of Arabidopsis CDKD;3 in meiotic progression and cytokinesis

Project description:Meiosis is a specialized cell division that halves the number of chromosomes in two consecutive rounds of chromosome segregation. In angiosperm plants is meiosis followed by mitotic divisions to form rudimentary haploid gametophytes. In Arabidopsis, termination of meiosis and transition to gametophytic development is governed by TDM1 and SMG7 that mediate inhibition of translation. Mutants deficient in this mechanism do not form tetrads, but instead undergo multiple cycles of aberrant nuclear divisions, that are likely caused by the failure to downregulate cyclin dependent kinases during meiotic exit. A suppressor screen to identify genes that contribute to meiotic exit uncovered a mutation in CDKD;3 that alleviates meiotic defects in smg7 deficient plants. The CDKD;3 deficiency prevents aberrant meiotic divisions observed in smg7 mutants, or delays their onset after initiation of cytokinesis, which permits formation of functional microspores. Although CDKD;3 acts as an activator of CDKA;1, the main cyclin dependent kinase that regulates meiosis, cdkd;3 mutation appears to promote meiotic exit independently of CDKA;1. Furthermore, analysis of CDKD;3 interactome revealed enrichment for proteins implicated in cytokinesis suggesting a more complex function of CDKD;3 in cell cycle regulation.

2022-12-31 | GSE210860 | GEO

Genome-wide binding of the cohesin protector Sgo1 in the presence and absence of the meiosis I-specific Spo13 protein

Project description:ChIP-seq profile of Sgo1 binding sites arrested in metaphase I by deletion of the APC/C activator CDC20. The aim of this experiment is to identify whether Sgo1 binding differs in wild type cells and cells deficient of the meiosis I-specific protein Spo13, which is required for retention of pericentromeric cohesin after metaphase I.

2019-04-25 | GSE112167 | GEO

Functional analysis of Cdc20 reveals a critical role of CRY box in mitotic checkpoint signaling

Project description:Accurate chromosome segregation is coordinated by the spindle assembly checkpoint (SAC) through its effector the mitotic checkpoint complex (MCC), to inhibit the anaphase-promoting complex or cyclosome (APC/C). Cdc20 is an essential mitotic regulator since it promotes mitotic exit through activating the APC/C and monitors kinetochore-microtubule attachment through activating the SAC. The proper functioning of Cdc20 requires multiple interactions with APC/C and MCC subunits. To functionally assess each of these interactions within cells requires efficient depletion of endogenous Cdc20, which is highly difficult to achieve by RNAi. Here we generated Cdc20 RNAi sensitive cell lines by CRISPR/Cas9 which display a penetrant metaphase arrest phenotype by a single RNAi treatment. In this null background, we accurately measured the contribution of each known motif of Cdc20 on APC/C and SAC activation. The CRY box, a previously identified degron was found to be critical for the SAC by promoting theMCC formation and stabilizing the interaction between the MCC and APC/C. These data reveal additionalregulatory components within the SAC and establish a novel method to interrogate Cdc20 function.

2023-12-06 | PXD045411 | Pride

Ordered dephosphorylation initiated by the selective proteolysis of cyclin B drives mitotic exit

Project description:APC/C-mediated proteolysis of cyclin B and securin promotes entry into anaphase, inactivating CDK1 and permitting chromosome segregation, respectively. Reduction of CDK1 activity relieves inhibition of the CDK1-opposing phosphatases PP1 and PP2A-B55 leading to dephosphorylation of substrates crucial for mitotic exit. Meanwhile, continued APC/C activity is required to target various proteins, including Aurora and Polo kinases, for degradation. Together, these activities orchestrate a complex series of events during mitotic exit. However, the relative importance of regulated proteolysis and dephosphorylation in dictating the order and timing of these events remains unclear. Using high temporal-resolution mass spectrometry, we compare the relative extent of proteolysis and protein dephosphorylation. This reveals highly-selective rapid (~5min half-life) proteolysis of cyclin B, securin and geminin at the metaphase to anaphase transition, followed by slow proteolysis (>60 min half-life) of other mitotic regulators. Protein dephosphorylation requires APC/C-dependent destruction of cyclin B and was resolved into PP1-dependent fast, intermediate and slow categories with unique sequence motifs. We conclude that dephosphorylation initiated by the selective proteolysis of cyclin B drives the bulk of changes observed during mitotic exit.

2020-09-04 | PXD019791 | Pride

Ordered dephosphorylation initiated by the selective proteolysis of cyclin B drives mitotic exit

2020-09-04 | PXD019786 | Pride

Ordered dephosphorylation initiated by the selective proteolysis of cyclin B drives mitotic exit

2020-09-04 | PXD019795 | Pride

Ordered dephosphorylation initiated by the selective proteolysis of cyclin B drives mitotic exit

2020-09-04 | PXD019788 | Pride

Ordered dephosphorylation initiated by the selective proteolysis of cyclin B drives mitotic exit

2020-09-04 | PXD019787 | Pride