scholarly journals BFA1 has multiple positive roles in directing late mitotic events in S. cerevisiae

2018 ◽  
Author(s):  
J Whalen ◽  
C Sniffen ◽  
S Gartland ◽  
M Vannini ◽  
A Seshan
Keyword(s):  
Budding Yeast ◽  
Spindle Pole Body ◽  
Biological Significance ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Genome Integrity ◽  
Mitotic Exit Network ◽  
M Phase ◽  
Regulation Of Cell Cycle ◽  
Spindle Position

ABSTRACTThe proper regulation of cell cycle transitions is paramount to the maintenance of cellular genome integrity. In budding yeast, the mitotic exit network (MEN) is a Ras-like signaling cascade that effects the transition from M phase to G1 during the cell division cycle in budding yeast. MEN activation is tightly regulated. It occurs during anaphase and is coupled to mitotic spindle position by the spindle position checkpoint (SPoC). Bfa1 is a key component of the SPoC and functions as part of a two-component GAP complex along with Bub2. The GAP activity of Bfa1-Bub2 keeps the MEN GTPase Tem1 inactive in cells with mispositioned spindles, thereby preventing inappropriate mitotic exit and preserving genome integrity. Interestingly, a GAP-independent role for Bfa1 in mitotic exit regulation has been previously identified. However the nature of this Bub2-independent role and its biological significance are not understood. Here we show that Bfa1 also activates the MEN by promoting the localization of Tem1 primarily to the daughter spindle pole body (dSPB). We demonstrate that the overexpression of BFA1 is lethal due to defects in Tem1 localization, which is required for its activity. In addition, our studies demonstrate a Tem1-independent role for Bfa1 in promoting proper cytokinesis. Cells lacking TEM1, in which the essential mitotic exit function is bypassed, exhibit cytokinesis defects. These defects are suppressed by the overexpression of BFA1. We conclude that Bfa1 functions to both inhibit and activate late mitotic events.

scholarly journals The Differential Roles of Budding Yeast Tem1p, Cdc15p, and Bub2p Protein Dynamics in Mitotic Exit

2004 ◽  
Vol 15 (4) ◽  
pp. 1519-1532 ◽  
Author(s):  
Jeffrey N. Molk ◽  
Scott C. Schuyler ◽  
Jenny Y. Liu ◽  
James G. Evans ◽  
E. D. Salmon ◽  
...  
Keyword(s):  
Budding Yeast ◽  
Protein Localization ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Yeast Saccharomyces Cerevisiae ◽  
Late Anaphase ◽  
Gfp Fluorescence ◽  
Mitotic Exit Network

In the budding yeast Saccharomyces cerevisiae the mitotic spindle must be positioned along the mother-bud axis to activate the mitotic exit network (MEN) in anaphase. To examine MEN proteins during mitotic exit, we imaged the MEN activators Tem1p and Cdc15p and the MEN regulator Bub2p in vivo. Quantitative live cell fluorescence microscopy demonstrated the spindle pole body that segregated into the daughter cell (dSPB) signaled mitotic exit upon penetration into the bud. Activation of mitotic exit was associated with an increased abundance of Tem1p-GFP and the localization of Cdc15p-GFP on the dSPB. In contrast, Bub2p-GFP fluorescence intensity decreased in mid-to-late anaphase on the dSPB. Therefore, MEN protein localization fluctuates to switch from Bub2p inhibition of mitotic exit to Cdc15p activation of mitotic exit. The mechanism that elevates Tem1p-GFP abundance in anaphase is specific to dSPB penetration into the bud and Dhc1p and Lte1p promote Tem1p-GFP localization. Finally, fluorescence recovery after photobleaching (FRAP) measurements revealed Tem1p-GFP is dynamic at the dSPB in late anaphase. These data suggest spindle pole penetration into the bud activates mitotic exit, resulting in Tem1p and Cdc15p persistence at the dSPB to initiate the MEN signal cascade.

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.

scholarly journals Novel Functional Dissection of the Localization-Specific Roles of Budding Yeast Polo Kinase Cdc5p

2004 ◽  
Vol 24 (22) ◽  
pp. 9873-9886 ◽  
Author(s):  
Jung-Eun Park ◽  
Chong J. Park ◽  
Krisada Sakchaisri ◽  
Tatiana Karpova ◽  
Satoshi Asano ◽  
...  
Keyword(s):  
Budding Yeast ◽  
Spindle Pole Body ◽  
Kinase Domain ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Negative Regulator ◽  
Triple Mutant ◽  
Polo Kinase ◽  
Bud Neck ◽  
M Phase

ABSTRACT Budding yeast polo kinase Cdc5p localizes to the spindle pole body (SPB) and to the bud-neck and plays multiple roles during M-phase progression. To dissect localization-specific mitotic functions of Cdc5p, we tethered a localization-defective N-terminal kinase domain of Cdc5p (Cdc5pΔC) to the SPB or to the bud-neck with components specifically localizing to one of these sites and characterized these mutants in a cdc5Δ background. Characterization of a viable, SPB-localizing, CDC5ΔC-CNM67 mutant revealed that it is defective in timely degradation of Swe1p, a negative regulator of Cdc28p. Loss of BFA1, a negative regulator of mitotic exit, rescued the lethality of a neck-localizing CDC5ΔC-CDC12 or CDC5ΔC-CDC3 mutant but yielded severe defects in cytokinesis. These data suggest that the SPB-associated Cdc5p activity is critical for both mitotic exit and cytokinesis, whereas the bud neck-localized Cdc5p is required for proper Swe1p regulation. Interestingly, a cdc5Δ bfa1Δ swe1Δ triple mutant is viable but grows slowly, whereas cdc5Δ cells bearing both CDC5ΔC-CNM67 and CDC5ΔC-CDC12 grow well with only a mild cell cycle delay. Thus, SPB- and the bud-neck-localized Cdc5p control most of the critical Cdc5p functions and downregulation of Bfa1p and Swe1p at the respective locations are two critical factors that require Cdc5p.

scholarly journals LTE1 promotes exit from mitosis by multiple mechanisms

2016 ◽  
Vol 27 (25) ◽  
pp. 3991-4001 ◽  
Author(s):  
Jill E. Falk ◽  
Ian W. Campbell ◽  
Kelsey Joyce ◽  
Jenna Whalen ◽  
Anupama Seshan ◽  
...  
Keyword(s):  
Mother Cell ◽  
Regulatory Elements ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Genome Integrity ◽  
Cell Compartment ◽  
Activating Function ◽  
Spindle Pole Bodies ◽  
Mitotic Exit Network ◽  
Spindle Position

In budding yeast, alignment of the anaphase spindle along the mother–bud axis is crucial for maintaining genome integrity. If the anaphase spindle becomes misaligned in the mother cell compartment, cells arrest in anaphase because the mitotic exit network (MEN), an essential Ras-like GTPase signaling cascade, is inhibited by the spindle position checkpoint (SPoC). Distinct localization patterns of MEN and SPoC components mediate MEN inhibition. Most components of the MEN localize to spindle pole bodies. If the spindle becomes mispositioned in the mother cell compartment, cells arrest in anaphase due to inhibition of the MEN by the mother cell–restricted SPoC kinase Kin4. Here we show that a bud-localized activating signal is necessary for full MEN activation. We identify Lte1 as this signal and show that Lte1 activates the MEN in at least two ways. It inhibits small amounts of Kin4 that are present in the bud via its central domain. An additional MEN-activating function of Lte1 is mediated by its N- and C-terminal GEF domains, which, we propose, directly activate the MEN GTPase Tem1. We conclude that control of the MEN by spindle position is exerted by both negative and positive regulatory elements that control the pathway’s GTPase activity.

scholarly journals Spatial signals link exit from mitosis to spindle position

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Jill Elaine Falk ◽  
Dai Tsuchiya ◽  
Jolien Verdaasdonk ◽  
Soni Lacefield ◽  
Kerry Bloom ◽  
...  
Keyword(s):  
Spindle Pole ◽  
Mitotic Exit ◽  
Zone Model ◽  
Cytoplasmic Microtubule ◽  
Binucleate Cells ◽  
Spindle Pole Bodies ◽  
Mitotic Exit Network ◽  
Bud Neck ◽  
Competing Models ◽  
Spindle Position

In budding yeast, if the spindle becomes mispositioned, cells prevent exit from mitosis by inhibiting the mitotic exit network (MEN). The MEN is a signaling cascade that localizes to spindle pole bodies (SPBs) and activates the phosphatase Cdc14. There are two competing models that explain MEN regulation by spindle position. In the 'zone model', exit from mitosis occurs when a MEN-bearing SPB enters the bud. The 'cMT-bud neck model' posits that cytoplasmic microtubule (cMT)-bud neck interactions prevent MEN activity. Here we find that 1) eliminating cMT– bud neck interactions does not trigger exit from mitosis and 2) loss of these interactions does not precede Cdc14 activation. Furthermore, using binucleate cells, we show that exit from mitosis occurs when one SPB enters the bud despite the presence of a mispositioned spindle. We conclude that exit from mitosis is triggered by a correctly positioned spindle rather than inhibited by improper spindle position.

scholarly journals The cortical protein Lte1 promotes mitotic exit by inhibiting the spindle position checkpoint kinase Kin4

2011 ◽  
Vol 193 (6) ◽  
pp. 1033-1048 ◽  
Author(s):  
Daniela Trinca Bertazzi ◽  
Bahtiyar Kurtulmus ◽  
Gislene Pereira
Keyword(s):  
Kinase Activity ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Cell Protein ◽  
Cell Axis ◽  
Pole Body ◽  
Catalytically Active ◽  
Surveillance Mechanism ◽  
Spindle Position

The spindle position checkpoint (SPOC) is an essential surveillance mechanism that allows mitotic exit only when the spindle is correctly oriented along the cell axis. Key SPOC components are the kinase Kin4 and the Bub2–Bfa1 GAP complex that inhibit the mitotic exit–promoting GTPase Tem1. During an unperturbed cell cycle, Kin4 associates with the mother spindle pole body (mSPB), whereas Bub2–Bfa1 is at the daughter SPB (dSPB). When the spindle is mispositioned, Bub2–Bfa1 and Kin4 bind to both SPBs, which enables Kin4 to phosphorylate Bfa1 and thereby block mitotic exit. Here, we show that the daughter cell protein Lte1 physically interacts with Kin4 and inhibits Kin4 kinase activity. Specifically, Lte1 binds to catalytically active Kin4 and promotes Kin4 hyperphosphorylation, which restricts Kin4 binding to the mSPB. This Lte1-mediated exclusion of Kin4 from the dSPB is essential for proper mitotic exit of cells with a correctly aligned spindle. Therefore, Lte1 promotes mitotic exit by inhibiting Kin4 activity at the dSPB.

scholarly journals A non-canonical Hippo pathway regulates spindle disassembly and cytokinesis during meiosis in Saccharomyces cerevisiae

2020 ◽  
Author(s):  
Scott M. Paulissen ◽  
Cindy A. Hunt ◽  
Christian J. Slubowski ◽  
Yao Yu ◽  
Dang Truong ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hippo Pathway ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Prospore Membrane ◽  
Mitotic Exit Network ◽  
Similar Phenotype ◽  
Spindle Disassembly ◽  
Ndr Kinase

ABSTRACTMeiosis in the budding yeast Saccharomyces cerevisiae is used to create haploid yeast spores from a diploid mother cell. During meiosis II, cytokinesis occurs by closure of the prospore membrane, a membrane that initiates at the spindle pole body and grows to surround each of the haploid meiotic products. Timely prospore membrane closure requires SPS1, which encodes a STE20-family GCKIII kinase. To identify genes that may activate SPS1, we utilized a histone phosphorylation defect of sps1 mutants to screen for genes with a similar phenotype and found that cdc15 shared this phenotype. CDC15 encodes a Hippo-like kinase that is part of the mitotic exit network. We find that Sps1 complexes with Cdc15, that Sps1 phosphorylation requires Cdc15, and that CDC15 is also required for timely prospore membrane closure. We also find that SPS1, like CDC15, is required for meiosis II spindle disassembly and sustained anaphase II release of Cdc14 in meiosis. However, the NDR-kinase complex encoded by DBF2/DBF20 MOB1 which functions downstream of CDC15 in mitotic cells, does not appear to play a role in spindle disassembly, timely prospore membrane closure, or sustained anaphase II Cdc14 release. Taken together, our results suggest that the mitotic exit network is rewired for exit from meiosis II, such that SPS1 replaces the NDR-kinase complex downstream of CDC15.

scholarly journals A lysine deacetylase Hos3 is targeted to the bud neck and involved in the spindle position checkpoint

2014 ◽  
Vol 25 (18) ◽  
pp. 2720-2734 ◽  
Author(s):  
Mengqiao Wang ◽  
Ruth N. Collins
Keyword(s):  
Spindle Pole Body ◽  
Neck Region ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Spindle Orientation ◽  
Lysine Deacetylase ◽  
Bud Neck ◽  
Morphogenesis Checkpoint ◽  
Spindle Position

An increasing number of cellular activities can be regulated by reversible lysine acetylation. Targeting the enzymes responsible for such posttranslational modifications is instrumental in defining their substrates and functions in vivo. Here we show that a Saccharomyces cerevisiae lysine deacetylase, Hos3, is asymmetrically targeted to the daughter side of the bud neck and to the daughter spindle pole body (SPB). The morphogenesis checkpoint member Hsl7 recruits Hos3 to the neck region. Cells with a defect in spindle orientation trigger Hos3 to load onto both SPBs. When associated symmetrically with both SPBs, Hos3 functions as a spindle position checkpoint (SPOC) component to inhibit mitotic exit. Neck localization of Hos3 is essential for its symmetric association with SPBs in cells with misaligned spindles. Our data suggest that Hos3 facilitates cross-talk between the morphogenesis checkpoint and the SPOC as a component of the intricate monitoring of spindle orientation after mitotic entry and before commitment to mitotic exit.

scholarly journals A Noncanonical Hippo Pathway Regulates Spindle Disassembly and Cytokinesis During Meiosis in Saccharomyces cerevisiae

Genetics ◽  
2020 ◽  
Vol 216 (2) ◽  
pp. 447-462
Author(s):  
Scott M. Paulissen ◽  
Cindy A. Hunt ◽  
Brian C. Seitz ◽  
Christian J. Slubowski ◽  
Yao Yu ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hippo Pathway ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Link Type ◽  
Prospore Membrane ◽  
Mitotic Exit Network ◽  
Spindle Disassembly ◽  
Ndr Kinase

Meiosis in the budding yeast Saccharomyces cerevisiae is used to create haploid yeast spores from a diploid mother cell. During meiosis II, cytokinesis occurs by closure of the prospore membrane, a membrane that initiates at the spindle pole body and grows to surround each of the haploid meiotic products. Timely prospore membrane closure requires SPS1, which encodes an STE20 family GCKIII kinase. To identify genes that may activate SPS1, we utilized a histone phosphorylation defect of sps1 mutants to screen for genes with a similar phenotype and found that cdc15 shared this phenotype. CDC15 encodes a Hippo-like kinase that is part of the mitotic exit network. We find that Sps1 complexes with Cdc15, that Sps1 phosphorylation requires Cdc15, and that CDC15 is also required for timely prospore membrane closure. We also find that SPS1, like CDC15, is required for meiosis II spindle disassembly and sustained anaphase II release of Cdc14 in meiosis. However, the NDR-kinase complex encoded by DBF2/DBF20MOB1 which functions downstream of CDC15 in mitotic cells, does not appear to play a role in spindle disassembly, timely prospore membrane closure, or sustained anaphase II Cdc14 release. Taken together, our results suggest that the mitotic exit network is rewired for exit from meiosis II, such that SPS1 replaces the NDR-kinase complex downstream of CDC15.

Sign in / Sign up

Export Citation Format

Share Document