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Joshua IM, Lin M, Mardjuki A, Mazzola A, Höfken T. A Protein-Protein Interaction Analysis Suggests a Wide Range of New Functions for the p21-Activated Kinase (PAK) Ste20. Int J Mol Sci 2023; 24:15916. [PMID: 37958899 PMCID: PMC10647699 DOI: 10.3390/ijms242115916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/25/2023] [Accepted: 10/30/2023] [Indexed: 11/15/2023] Open
Abstract
The p21-activated kinases (PAKs) are important signaling proteins. They contribute to a surprisingly wide range of cellular processes and play critical roles in a number of human diseases including cancer, neurological disorders and cardiac diseases. To get a better understanding of PAK functions, mechanisms and integration of various cellular activities, we screened for proteins that bind to the budding yeast PAK Ste20 as an example, using the split-ubiquitin technique. We identified 56 proteins, most of them not described previously as Ste20 interactors. The proteins fall into a small number of functional categories such as vesicle transport and translation. We analyzed the roles of Ste20 in glucose metabolism and gene expression further. Ste20 has a well-established role in the adaptation to changing environmental conditions through the stimulation of mitogen-activated protein kinase (MAPK) pathways which eventually leads to transcription factor activation. This includes filamentous growth, an adaptation to nutrient depletion. Here we show that Ste20 also induces filamentous growth through interaction with nuclear proteins such as Sac3, Ctk1 and Hmt1, key regulators of gene expression. Combining our observations and the data published by others, we suggest that Ste20 has several new and unexpected functions.
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Affiliation(s)
| | - Meng Lin
- Institute of Biochemistry, Kiel University, 24118 Kiel, Germany
| | - Ariestia Mardjuki
- Division of Biosciences, Brunel University London, Uxbridge UB8 3PH, UK; (I.M.J.)
| | - Alessandra Mazzola
- Division of Biosciences, Brunel University London, Uxbridge UB8 3PH, UK; (I.M.J.)
- Department of Biopathology and Medical and Forensic Biotechnologies, University of Palermo, 90133 Palermo, Italy
| | - Thomas Höfken
- Division of Biosciences, Brunel University London, Uxbridge UB8 3PH, UK; (I.M.J.)
- Institute of Biochemistry, Kiel University, 24118 Kiel, Germany
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2
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Huda M, Bektas SN, Bekdas B, Caydasi AK. The signalling lipid PI3,5P 2 is essential for timely mitotic exit. Open Biol 2023; 13:230125. [PMID: 37751887 PMCID: PMC10522413 DOI: 10.1098/rsob.230125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 08/15/2023] [Indexed: 09/28/2023] Open
Abstract
Coordination of mitotic exit with chromosome segregation is key for successful mitosis. Mitotic exit in budding yeast is executed by the mitotic exit network (MEN), which is negatively regulated by the spindle position checkpoint (SPOC). SPOC kinase Kin4 is crucial for SPOC activation in response to spindle positioning defects. Here, we report that the lysosomal signalling lipid phosphatidylinositol-3,5-bisphosphate (PI3,5P2) has an unanticipated role in the timely execution of mitotic exit. We show that the lack of PI3,5P2 causes a delay in mitotic exit, whereas elevated levels of PI3,5P2 accelerates mitotic exit in mitotic exit defective cells. Our data indicate that PI3,5P2 promotes mitotic exit in part through impairment of Kin4. This process is largely dependent on the known PI3,5P2 effector protein Atg18. Our work thus uncovers a novel link between PI3,5P2 and mitotic exit.
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Affiliation(s)
- Mariam Huda
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Seyma Nur Bektas
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Baris Bekdas
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Ayse Koca Caydasi
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
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3
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Ekal L, Alqahtani AMS, Schuldiner M, Zalckvar E, Hettema EH, Ayscough KR. Spindle Position Checkpoint Kinase Kin4 Regulates Organelle Transport in Saccharomyces cerevisiae. Biomolecules 2023; 13:1098. [PMID: 37509134 PMCID: PMC10377308 DOI: 10.3390/biom13071098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/29/2023] [Accepted: 07/04/2023] [Indexed: 07/30/2023] Open
Abstract
Membrane-bound organelles play important, frequently essential, roles in cellular metabolism in eukaryotes. Hence, cells have evolved molecular mechanisms to closely monitor organelle dynamics and maintenance. The actin cytoskeleton plays a vital role in organelle transport and positioning across all eukaryotes. Studies in the budding yeast Saccharomyces cerevisiae (S. cerevisiae) revealed that a block in actomyosin-dependent transport affects organelle inheritance to daughter cells. Indeed, class V Myosins, Myo2, and Myo4, and many of their organelle receptors, have been identified as key factors in organelle inheritance. However, the spatiotemporal regulation of yeast organelle transport remains poorly understood. Using peroxisome inheritance as a proxy to study actomyosin-based organelle transport, we performed an automated genome-wide genetic screen in S. cerevisiae. We report that the spindle position checkpoint (SPOC) kinase Kin4 and, to a lesser extent, its paralog Frk1, regulates peroxisome transport, independent of their role in the SPOC. We show that Kin4 requires its kinase activity to function and that both Kin4 and Frk1 protect Inp2, the peroxisomal Myo2 receptor, from degradation in mother cells. In addition, vacuole inheritance is also affected in kin4/frk1-deficient cells, suggesting a common regulatory mechanism for actin-based transport for these two organelles in yeast. More broadly our findings have implications for understanding actomyosin-based transport in cells.
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Affiliation(s)
- Lakhan Ekal
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Abdulaziz M S Alqahtani
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
- Department of Biology, Faculty of Science, University of Bisha, P.O. Box 551, Bisha 61922, Saudi Arabia
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Einat Zalckvar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ewald H Hettema
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
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4
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Caydasi AK, Khmelinskii A, Darieva Z, Kurtulmus B, Knop M, Pereira G. SWR1 chromatin remodeling complex prevents mitotic slippage during spindle position checkpoint arrest. Mol Biol Cell 2023; 34:ar11. [PMID: 36542480 PMCID: PMC9930528 DOI: 10.1091/mbc.e20-03-0179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Faithful chromosome segregation in budding yeast requires correct positioning of the mitotic spindle along the mother to daughter cell polarity axis. When the anaphase spindle is not correctly positioned, a surveillance mechanism, named as the spindle position checkpoint (SPOC), prevents the progression out of mitosis until correct spindle positioning is achieved. How SPOC works on a molecular level is not well understood. Here we performed a genome-wide genetic screen to search for components required for SPOC. We identified the SWR1 chromatin-remodeling complex (SWR1-C) among several novel factors that are essential for SPOC integrity. Cells lacking SWR1-C were able to activate SPOC upon spindle misorientation but underwent mitotic slippage upon prolonged SPOC arrest. This mitotic slippage required the Cdc14-early anaphase release pathway and other factors including the SAGA (Spt-Ada-Gcn5 acetyltransferase) histone acetyltransferase complex, proteasome components and the mitotic cyclin-dependent kinase inhibitor Sic1. Together, our data establish a novel link between SWR1-C chromatin remodeling and robust checkpoint arrest in late anaphase.
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Affiliation(s)
- Ayse Koca Caydasi
- Centre for Organismal Studies (COS), University of Heidelberg, Germany,Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | | | - Zoulfia Darieva
- Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Bahtiyar Kurtulmus
- Centre for Organismal Studies (COS), University of Heidelberg, Germany,European Molecular Biology Laboratories (EMBL), Heidelberg, Germany
| | - Michael Knop
- Centre for Molecular Biology (ZMBH), University of Heidelberg, Germany
| | - Gislene Pereira
- Centre for Organismal Studies (COS), University of Heidelberg, Germany,Centre for Molecular Biology (ZMBH), University of Heidelberg, Germany,German Cancer Research Centre (DKFZ), DKFZ-ZMBH Alliance, University of Heidelberg, Germany,*Address correspondence to: Gislene Pereira ()
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5
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Rathi S, Polat I, Pereira G. The budding yeast GSK-3 homologue Mck1 is an essential component of the spindle position checkpoint. Open Biol 2022; 12:220203. [PMID: 36321416 PMCID: PMC9627454 DOI: 10.1098/rsob.220203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The spindle position checkpoint (SPOC) is a mitotic surveillance mechanism in Saccharomyces cerevisiae that prevents cells from completing mitosis in response to spindle misalignment, thereby contributing to genomic integrity. The kinase Kin4, one of the most downstream SPOC components, is essential to stop the mitotic exit network (MEN), a signalling pathway that promotes the exit from mitosis and cell division. Previous work, however, suggested that a Kin4-independent pathway contributes to SPOC, yet the underlying mechanisms remain elusive. Here, we established the glycogen-synthase-kinase-3 (GSK-3) homologue Mck1, as a novel component that works independently of Kin4 to engage SPOC. Our data indicate that both Kin4 and Mck1 work in parallel to counteract MEN activation by the Cdc14 early anaphase release (FEAR) network. We show that Mck1's function in SPOC is mediated by the pre-replication complex protein and mitotic cyclin-dependent kinase (M-Cdk) inhibitor, Cdc6, which is degraded in a Mck1-dependent manner prior to mitosis. Moderate overproduction of Cdc6 phenocopies MCK1 deletion and causes SPOC deficiency via its N-terminal, M-Cdk inhibitory domain. Our data uncover an unprecedented role of GSK-3 kinases in coordinating spindle orientation with cell cycle progression.
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Affiliation(s)
- Siddhi Rathi
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany,Heidelberg Biosciences International Graduate School (HBIGS) and Faculty of Biosciences, University of Heidelberg, Heidelberg, Germany,German Academic Exchange Service (DAAD), Bonn, Germany
| | - Irem Polat
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - Gislene Pereira
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany,Centre for Molecular Biology (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Centre (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
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6
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Rathi S, Polat I, Pereira G. The budding yeast GSK-3 homologue Mck1 is an essential component of the spindle position checkpoint. Open Biol 2022. [PMID: 36321416 DOI: 10.6084/m9.figshare.c.6261880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The spindle position checkpoint (SPOC) is a mitotic surveillance mechanism in Saccharomyces cerevisiae that prevents cells from completing mitosis in response to spindle misalignment, thereby contributing to genomic integrity. The kinase Kin4, one of the most downstream SPOC components, is essential to stop the mitotic exit network (MEN), a signalling pathway that promotes the exit from mitosis and cell division. Previous work, however, suggested that a Kin4-independent pathway contributes to SPOC, yet the underlying mechanisms remain elusive. Here, we established the glycogen-synthase-kinase-3 (GSK-3) homologue Mck1, as a novel component that works independently of Kin4 to engage SPOC. Our data indicate that both Kin4 and Mck1 work in parallel to counteract MEN activation by the Cdc14 early anaphase release (FEAR) network. We show that Mck1's function in SPOC is mediated by the pre-replication complex protein and mitotic cyclin-dependent kinase (M-Cdk) inhibitor, Cdc6, which is degraded in a Mck1-dependent manner prior to mitosis. Moderate overproduction of Cdc6 phenocopies MCK1 deletion and causes SPOC deficiency via its N-terminal, M-Cdk inhibitory domain. Our data uncover an unprecedented role of GSK-3 kinases in coordinating spindle orientation with cell cycle progression.
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Affiliation(s)
- Siddhi Rathi
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany.,Heidelberg Biosciences International Graduate School (HBIGS) and Faculty of Biosciences, University of Heidelberg, Heidelberg, Germany.,German Academic Exchange Service (DAAD), Bonn, Germany
| | - Irem Polat
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - Gislene Pereira
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany.,Centre for Molecular Biology (ZMBH), University of Heidelberg, Heidelberg, Germany.,German Cancer Research Centre (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
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7
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Kocakaplan D, Karabürk H, Dilege C, Kirdök I, Bektas SN, Caydasi AK. Protein phosphatase 1 in association with Bud14 inhibits mitotic exit in Saccharomyces cerevisiae. eLife 2021; 10:72833. [PMID: 34633288 PMCID: PMC8577847 DOI: 10.7554/elife.72833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/08/2021] [Indexed: 11/18/2022] Open
Abstract
Mitotic exit in budding yeast is dependent on correct orientation of the mitotic spindle along the cell polarity axis. When accurate positioning of the spindle fails, a surveillance mechanism named the spindle position checkpoint (SPOC) prevents cells from exiting mitosis. Mutants with a defective SPOC become multinucleated and lose their genomic integrity. Yet, a comprehensive understanding of the SPOC mechanism is missing. In this study, we identified the type 1 protein phosphatase, Glc7, in association with its regulatory protein Bud14 as a novel checkpoint component. We further showed that Glc7-Bud14 promotes dephosphorylation of the SPOC effector protein Bfa1. Our results suggest a model in which two mechanisms act in parallel for a robust checkpoint response: first, the SPOC kinase Kin4 isolates Bfa1 away from the inhibitory kinase Cdc5, and second, Glc7-Bud14 dephosphorylates Bfa1 to fully activate the checkpoint effector.
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Affiliation(s)
- Dilara Kocakaplan
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Hüseyin Karabürk
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Cansu Dilege
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Idil Kirdök
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Seyma Nur Bektas
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Ayse Koca Caydasi
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
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8
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Howell RSM, Klemm C, Thorpe PH, Csikász-Nagy A. Unifying the mechanism of mitotic exit control in a spatiotemporal logical model. PLoS Biol 2020; 18:e3000917. [PMID: 33180788 PMCID: PMC7685450 DOI: 10.1371/journal.pbio.3000917] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 11/24/2020] [Accepted: 10/09/2020] [Indexed: 11/18/2022] Open
Abstract
The transition from mitosis into the first gap phase of the cell cycle in budding yeast is controlled by the Mitotic Exit Network (MEN). The network interprets spatiotemporal cues about the progression of mitosis and ensures that release of Cdc14 phosphatase occurs only after completion of key mitotic events. The MEN has been studied intensively; however, a unified understanding of how localisation and protein activity function together as a system is lacking. In this paper, we present a compartmental, logical model of the MEN that is capable of representing spatial aspects of regulation in parallel to control of enzymatic activity. We show that our model is capable of correctly predicting the phenotype of the majority of mutants we tested, including mutants that cause proteins to mislocalise. We use a continuous time implementation of the model to demonstrate that Cdc14 Early Anaphase Release (FEAR) ensures robust timing of anaphase, and we verify our findings in living cells. Furthermore, we show that our model can represent measured cell-cell variation in Spindle Position Checkpoint (SPoC) mutants. This work suggests a general approach to incorporate spatial effects into logical models. We anticipate that the model itself will be an important resource to experimental researchers, providing a rigorous platform to test hypotheses about regulation of mitotic exit.
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Affiliation(s)
- Rowan S M Howell
- The Francis Crick Institute, London, United Kingdom.,Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Cinzia Klemm
- School of Biological and Chemical Sciences, Queen Mary University, London, United Kingdom
| | - Peter H Thorpe
- School of Biological and Chemical Sciences, Queen Mary University, London, United Kingdom
| | - Attila Csikász-Nagy
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom.,Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
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9
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Rsr1 Palmitoylation and GTPase Activity Status Differentially Coordinate Nuclear, Septin, and Vacuole Dynamics in Candida albicans. mBio 2020; 11:mBio.01666-20. [PMID: 33051364 PMCID: PMC7554666 DOI: 10.1128/mbio.01666-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Directional growth and tissue invasion by hyphae of the pathogenic fungus, Candida albicans, are disrupted by deletion of the small GTPase, Rsr1, which localizes Cdc42 and its kinase, Cla4, to the site of polarized growth. We investigated additional abnormalities observed in rsr1Δ hyphae, including vacuole development, cytoplasm inheritance, mitochondrial morphology, septin ring organization, nuclear division and migration, and branching frequency, which together demonstrate a fundamental role for Rsr1 in cellular organization. Rsr1 contains a C-terminal CCAAX box, which putatively undergoes both reversible palmitoylation and farnesylation for entry into the secretory pathway. We expressed variants of Rsr1 with mutated C244 or C245, or which lacked GTPase activity (Rsr1K16N and Rsr1G12V), in the rsr1Δ background and compared the resulting phenotypes with those of mutants lacking Bud5 (Rsr1 GEF), Bud2 (Rsr1 GAP), or Cla4. Bud5 was required only for cell size and bud site selection in yeast, suggesting there are alternative activators for Rsr1 in hyphae. Septin ring and vacuole dynamics were restored by expression of unpalmitoylated Rsr1C244S, which localized to endomembranes, but not by cytoplasmic Rsr1C245A or GTP/GDP-locked Rsr1, suggesting Rsr1 functions at intracellular membranes in addition to the plasma membrane. Rsr1K16N or cytoplasmic Rsr1C245A restored normal nuclear division but not septin ring or vacuole dynamics. Rsr1-GDP therefore plays a specific role in suppressing START, which can be signaled from the cytosol. Via differential palmitoylation and activity states, Rsr1 operates at diverse cell sites to orchestrate proper nuclear division and inheritance during constitutive polarized growth. As cla4Δ phenocopied rsr1Δ, it is likely these functions involve Cdc42-Cla4 activity.IMPORTANCE Understanding how single eukaryotic cells self-organize to replicate and migrate is relevant to health and disease. In the fungal pathogen, Candida albicans, the small GTPase, Rsr1, guides the directional growth of hyphae that invade human tissue during life-threatening infections. Rsr1 is a Ras-like GTPase and a homolog of the conserved Rap1 subfamily, which directs migration in mammalian cells. Research into how this single GTPase delivers complex intracellular patterning is challenging established views of GTPase regulation, trafficking, and interaction. Here, we show that Rsr1 directly and indirectly coordinates the spatial and temporal development of key intracellular macrostructures, including septum formation and closure, vacuole dynamics, and nuclear division and segregation, as well as whole-cell morphology by determining branching patterns. Furthermore, we categorize these functions by differential Rsr1 localization and activity state and provide evidence to support the emerging view that the cytosolic pool of Ras-like GTPases is functionally active.
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Matellán L, Monje-Casas F. Regulation of Mitotic Exit by Cell Cycle Checkpoints: Lessons From Saccharomyces cerevisiae. Genes (Basel) 2020; 11:E195. [PMID: 32059558 PMCID: PMC7074328 DOI: 10.3390/genes11020195] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/07/2020] [Accepted: 02/11/2020] [Indexed: 02/06/2023] Open
Abstract
In order to preserve genome integrity and their ploidy, cells must ensure that the duplicated genome has been faithfully replicated and evenly distributed before they complete their division by mitosis. To this end, cells have developed highly elaborated checkpoints that halt mitotic progression when problems in DNA integrity or chromosome segregation arise, providing them with time to fix these issues before advancing further into the cell cycle. Remarkably, exit from mitosis constitutes a key cell cycle transition that is targeted by the main mitotic checkpoints, despite these surveillance mechanisms being activated by specific intracellular signals and acting at different stages of cell division. Focusing primarily on research carried out using Saccharomyces cerevisiae as a model organism, the aim of this review is to provide a general overview of the molecular mechanisms by which the major cell cycle checkpoints control mitotic exit and to highlight the importance of the proper regulation of this process for the maintenance of genome stability during the distribution of the duplicated chromosomes between the dividing cells.
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Affiliation(s)
| | - Fernando Monje-Casas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Spanish National Research Council (CSIC)—University of Seville—University Pablo de Olavide, Avda, Américo Vespucio, 24, 41092 Sevilla, Spain;
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11
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Howell RSM, Csikász-Nagy A, Thorpe PH. Synthetic Physical Interactions with the Yeast Centrosome. G3 (BETHESDA, MD.) 2019; 9:2183-2194. [PMID: 31076383 PMCID: PMC6643875 DOI: 10.1534/g3.119.400117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/02/2019] [Indexed: 12/30/2022]
Abstract
The yeast centrosome or Spindle Pole Body (SPB) is an organelle situated in the nuclear membrane, where it nucleates spindle microtubules and acts as a signaling hub. Various studies have explored the effects of forcing individual proteins to interact with the yeast SPB, however no systematic study has been performed. We used synthetic physical interactions to detect proteins that inhibit growth when forced to associate with the SPB. We found the SPB to be especially sensitive to relocalization, necessitating a novel data analysis approach. This novel analysis of SPI screening data shows that regions of the cell are locally more sensitive to forced relocalization than previously thought. Furthermore, we found a set of associations that result in elevated SPB number and, in some cases, multi-polar spindles. Since hyper-proliferation of centrosomes is a hallmark of cancer cells, these associations point the way for the use of yeast models in the study of spindle formation and chromosome segregation in cancer.
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Affiliation(s)
- Rowan S M Howell
- The Francis Crick Institute, London, NW1 1AT UK
- Randall Division of Cell and Molecular Biophysics, King's College, London, SE1 1UL UK
| | - Attila Csikász-Nagy
- Randall Division of Cell and Molecular Biophysics, King's College, London, SE1 1UL UK
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, 1083 Hungary
| | - Peter H Thorpe
- School of Biological and Chemical Sciences, Queen Mary University, London, E1 4NS UK
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12
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de Los Santos-Velázquez AI, de Oya IG, Manzano-López J, Monje-Casas F. Late rDNA Condensation Ensures Timely Cdc14 Release and Coordination of Mitotic Exit Signaling with Nucleolar Segregation. Curr Biol 2017; 27:3248-3263.e5. [PMID: 29056450 DOI: 10.1016/j.cub.2017.09.028] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 08/16/2017] [Accepted: 09/13/2017] [Indexed: 12/28/2022]
Abstract
The nucleolus plays a pivotal role in multiple key cellular processes. An illustrative example is the regulation of mitotic exit in Saccharomyces cerevisiae through the nucleolar sequestration of the Cdc14 phosphatase. The peculiar structure of the nucleolus, however, has also its drawbacks. The repetitive nature of the rDNA gives rise to cohesion-independent linkages whose resolution in budding yeast requires the Cdc14-dependent inhibition of rRNA transcription, which facilitates condensin accessibility to this locus. Thus, the rDNA condenses and segregates later than most other yeast genomic regions. Here, we show that defective function of a small nucleolar ribonucleoprotein particle (snoRNP) assembly factor facilitates condensin accessibility to the rDNA and induces nucleolar hyper-condensation. Interestingly, this increased compaction of the nucleolus interferes with the proper release of Cdc14 from this organelle. This observation provides an explanation for the delayed rDNA condensation in budding yeast, which is necessary to efficiently coordinate timely Cdc14 release and mitotic exit with nucleolar compaction and segregation.
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Affiliation(s)
- Ana Isabel de Los Santos-Velázquez
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Spanish National Research Council (CSIC), University of Seville, and University Pablo de Olavide, Avda. Américo Vespucio 24, 41092 Sevilla, Spain
| | - Inés G de Oya
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Spanish National Research Council (CSIC), University of Seville, and University Pablo de Olavide, Avda. Américo Vespucio 24, 41092 Sevilla, Spain
| | - Javier Manzano-López
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Spanish National Research Council (CSIC), University of Seville, and University Pablo de Olavide, Avda. Américo Vespucio 24, 41092 Sevilla, Spain
| | - Fernando Monje-Casas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Spanish National Research Council (CSIC), University of Seville, and University Pablo de Olavide, Avda. Américo Vespucio 24, 41092 Sevilla, Spain.
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