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PP2A Functions during Mitosis and Cytokinesis in Yeasts. Int J Mol Sci 2019; 21:ijms21010264. [PMID: 31906018 PMCID: PMC6981662 DOI: 10.3390/ijms21010264] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 12/23/2019] [Accepted: 12/24/2019] [Indexed: 12/13/2022] Open
Abstract
Protein phosphorylation is a common mechanism for the regulation of cell cycle progression. The opposing functions of cell cycle kinases and phosphatases are crucial for accurate chromosome segregation and exit from mitosis. Protein phosphatases 2A are heterotrimeric complexes that play essential roles in cell growth, proliferation, and regulation of the cell cycle. Here, we review the function of the protein phosphatase 2A family as the counteracting force for the mitotic kinases. We focus on recent findings in the regulation of mitotic exit and cytokinesis by PP2A phosphatases in S. cerevisiae and other fungal species.
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Campbell IW, Zhou X, Amon A. The Mitotic Exit Network integrates temporal and spatial signals by distributing regulation across multiple components. eLife 2019; 8:41139. [PMID: 30672733 PMCID: PMC6363386 DOI: 10.7554/elife.41139] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 01/10/2019] [Indexed: 12/30/2022] Open
Abstract
GTPase signal transduction pathways control cellular decision making by integrating multiple cellular events into a single signal. The Mitotic Exit Network (MEN), a Ras-like GTPase signaling pathway, integrates spatial and temporal cues to ensure that cytokinesis only occurs after the genome has partitioned between mother and daughter cells during anaphase. Here we show that signal integration does not occur at a single step of the pathway. Rather, sequential components of the pathway are controlled in series by different signals. The spatial signal, nuclear position, regulates the MEN GTPase Tem1. The temporal signal, commencement of anaphase, is mediated by mitotic cyclin-dependent kinase (CDK) phosphorylation of the GTPase's downstream kinases. We propose that integrating multiple signals through sequential steps in the GTPase pathway represents a generalizable principle in GTPase signaling and explains why intracellular signal transmission is a multi-step process. Serial signal integration rather than signal amplification makes multi-step signal transduction necessary.
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Affiliation(s)
- Ian Winsten Campbell
- David H. Koch Institute for Integrative Cancer Research, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States
| | - Xiaoxue Zhou
- David H. Koch Institute for Integrative Cancer Research, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States
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Budding Yeast BFA1 Has Multiple Positive Roles in Directing Late Mitotic Events. G3-GENES GENOMES GENETICS 2018; 8:3397-3410. [PMID: 30166350 PMCID: PMC6222586 DOI: 10.1534/g3.118.200672] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The proper regulation of cell cycle transitions is paramount to the maintenance of cellular genome integrity. In Saccharomyces cerevisiae, 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.
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4
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Candida albicans Cdc15 is essential for mitotic exit and cytokinesis. Sci Rep 2018; 8:8899. [PMID: 29891974 PMCID: PMC5995815 DOI: 10.1038/s41598-018-27157-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/30/2018] [Indexed: 12/21/2022] Open
Abstract
Candida albicans displays a variety of morphological forms, and the ability to switch forms must be linked with cell cycle control. In budding yeast the Mitotic Exit Network (MEN) acts to drive mitotic exit and signal for cytokinesis and cell separation. However, previous reports on the MEN in C. albicans have raised questions on its role in this organism, with the components analysed to date demonstrating differing levels of importance in the processes of mitotic exit, cytokinesis and cell separation. This work focuses on the role of the Cdc15 kinase in C. albicans and demonstrates that, similar to Saccharomyces cerevisiae, it plays an essential role in signalling for mitotic exit and cytokinesis. Cells depleted of Cdc15 developed into elongated filaments, a common response to cell cycle arrest in C. albicans. These filaments emerged exclusively from large budded cells, contained two nuclear bodies and exhibited a hyper-extended spindle, all characteristic of these cells failing to exit mitosis. Furthermore these filaments displayed a clear cytokinesis defect, and CDC15 over-expression led to aberrant cell separation following hyphal morphogenesis. Together, these results are consistent with Cdc15 playing an essential role in signalling for mitotic exit, cytokinesis and cell separation in C. albicans.
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Caydasi AK, Khmelinskii A, Duenas-Sanchez R, Kurtulmus B, Knop M, Pereira G. Temporal and compartment-specific signals coordinate mitotic exit with spindle position. Nat Commun 2017; 8:14129. [PMID: 28117323 PMCID: PMC5286211 DOI: 10.1038/ncomms14129] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 12/02/2016] [Indexed: 02/06/2023] Open
Abstract
The spatiotemporal control of mitotic exit is crucial for faithful chromosome segregation during mitosis. In budding yeast, the mitotic exit network (MEN) drives cells out of mitosis, whereas the spindle position checkpoint (SPOC) blocks MEN activity when the anaphase spindle is mispositioned. How the SPOC operates at a molecular level remains unclear. Here, we report novel insights into how mitotic signalling pathways orchestrate chromosome segregation in time and space. We establish that the key function of the central SPOC kinase, Kin4, is to counterbalance MEN activation by the cdc fourteen early anaphase release (FEAR) network in the mother cell compartment. Remarkably, Kin4 becomes dispensable for SPOC function in the absence of FEAR. Cells lacking both FEAR and Kin4 show that FEAR contributes to mitotic exit through regulation of the SPOC component Bfa1 and the MEN kinase Cdc15. Furthermore, we uncover controls that specifically promote mitotic exit in the daughter cell compartment. The mitotic exit network (MEN) triggers mitotic exit and can be blocked by the spindle position checkpoint (SPOC). Here the authors show that SPOC kinase Kin4 counterbalances MEN activation by the Cdc fourteen early anaphase release (FEAR) network in the mother cell and that in the absence of FEAR mitotic exit requires daughter cell-confined factors.
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Affiliation(s)
- Ayse Koca Caydasi
- DKFZ-ZMBH Alliance, Department of Cell and Tumour Biology, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.,Centre for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Anton Khmelinskii
- DKFZ-ZMBH Alliance, Centre for Molecular Biology (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Rafael Duenas-Sanchez
- DKFZ-ZMBH Alliance, Department of Cell and Tumour Biology, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.,Centre for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Bahtiyar Kurtulmus
- DKFZ-ZMBH Alliance, Department of Cell and Tumour Biology, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.,Centre for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Michael Knop
- DKFZ-ZMBH Alliance, Department of Cell and Tumour Biology, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.,DKFZ-ZMBH Alliance, Centre for Molecular Biology (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Gislene Pereira
- DKFZ-ZMBH Alliance, Department of Cell and Tumour Biology, German Cancer Research Centre (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.,Centre for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
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Asymmetric Localization of Components and Regulators of the Mitotic Exit Network at Spindle Pole Bodies. Methods Mol Biol 2017; 1505:183-193. [PMID: 27826865 DOI: 10.1007/978-1-4939-6502-1_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Most proteins of the Mitotic Exit Network (MEN) and their upstream regulators localize at spindle pole bodies (SPBs) at least in some stages of the cell cycle. Studying the SPB localization of MEN factors has been extremely useful to elucidate their biological roles, organize them in a hierarchical pathway, and define their dynamics under different conditions.Recruitment to SPBs of the small GTPase Tem1 and the downstream kinases Cdc15 and Mob1/Dbf2 is thought to be essential for Cdc14 activation and mitotic exit, while that of the upstream Tem1 regulators (the Kin4 kinase and the GTPase activating protein Bub2-Bfa1) is important for MEN inhibition upon spindle mispositioning. Here, we describe the detailed fluorescence microscopy procedures that we use in our lab to analyze the localization at SPBs of Mitotic Exit Network (MEN) components tagged with GFP or HA epitopes.
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Abstract
The Mitotic Exit Network (MEN) is an essential signaling pathway, closely related to the Hippo pathway in mammals, which promotes mitotic exit and initiates cytokinesis in the budding yeast Saccharomyces cerevisiae. Here, we summarize the current knowledge about the MEN components and their regulation.
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Affiliation(s)
- Bàrbara Baro
- Department of Pediatrics, Division of Infectious Diseases,Stanford University School of Medicine, Stanford, CA, USA.
| | - Ethel Queralt
- Cancer Epigenetics & Biology Program, Hospitalet de Llobregat, Barcelona, Spain.
| | - Fernando Monje-Casas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio, s/n. P.C.T. Cartuja 93., 41092, Sevilla, Spain.
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Perez AM, Finnigan GC, Roelants FM, Thorner J. Septin-Associated Protein Kinases in the Yeast Saccharomyces cerevisiae. Front Cell Dev Biol 2016; 4:119. [PMID: 27847804 PMCID: PMC5088441 DOI: 10.3389/fcell.2016.00119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 10/14/2016] [Indexed: 01/19/2023] Open
Abstract
Septins are a family of eukaryotic GTP-binding proteins that associate into linear rods, which, in turn, polymerize end-on-end into filaments, and further assemble into other, more elaborate super-structures at discrete subcellular locations. Hence, septin-based ensembles are considered elements of the cytoskeleton. One function of these structures that has been well-documented in studies conducted in budding yeast Saccharomyces cerevisiae is to serve as a scaffold that recruits regulatory proteins, which dictate the spatial and temporal control of certain aspects of the cell division cycle. In particular, septin-associated protein kinases couple cell cycle progression with cellular morphogenesis. Thus, septin-containing structures serve as signaling platforms that integrate a multitude of signals and coordinate key downstream networks required for cell cycle passage. This review summarizes what we currently understand about how the action of septin-associated protein kinases and their substrates control information flow to drive the cell cycle into and out of mitosis, to regulate bud growth, and especially to direct timely and efficient execution of cytokinesis and cell abscission. Thus, septin structures represent a regulatory node at the intersection of many signaling pathways. In addition, and importantly, the activities of certain septin-associated protein kinases also regulate the state of organization of the septins themselves, creating a complex feedback loop.
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Affiliation(s)
- Adam M Perez
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley Berkeley, CA, USA
| | - Gregory C Finnigan
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley Berkeley, CA, USA
| | - Françoise M Roelants
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley Berkeley, CA, USA
| | - Jeremy Thorner
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley Berkeley, CA, USA
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Juanes MA, Piatti S. The final cut: cell polarity meets cytokinesis at the bud neck in S. cerevisiae. Cell Mol Life Sci 2016; 73:3115-36. [PMID: 27085703 PMCID: PMC4951512 DOI: 10.1007/s00018-016-2220-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/22/2016] [Accepted: 04/05/2016] [Indexed: 02/07/2023]
Abstract
Cell division is a fundamental but complex process that gives rise to two daughter cells. It includes an ordered set of events, altogether called "the cell cycle", that culminate with cytokinesis, the final stage of mitosis leading to the physical separation of the two daughter cells. Symmetric cell division equally partitions cellular components between the two daughter cells, which are therefore identical to one another and often share the same fate. In many cases, however, cell division is asymmetrical and generates two daughter cells that differ in specific protein inheritance, cell size, or developmental potential. The budding yeast Saccharomyces cerevisiae has proven to be an excellent system to investigate the molecular mechanisms governing asymmetric cell division and cytokinesis. Budding yeast is highly polarized during the cell cycle and divides asymmetrically, producing two cells with distinct sizes and fates. Many components of the machinery establishing cell polarization during budding are relocalized to the division site (i.e., the bud neck) for cytokinesis. In this review we recapitulate how budding yeast cells undergo polarized processes at the bud neck for cell division.
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Affiliation(s)
- Maria Angeles Juanes
- Centre de Recherche en Biologie Cellulaire de Montpellier, 1919 Route de Mende, 34293, Montpellier, France
- Brandeis University, 415 South Street, Waltham, MA, 02454, USA
| | - Simonetta Piatti
- Centre de Recherche en Biologie Cellulaire de Montpellier, 1919 Route de Mende, 34293, Montpellier, France.
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10
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Abstract
The mammalian MST kinase family, which is related to the Hippo kinase in Drosophila melanogaster, includes five related proteins: MST1 (also called STK4), MST2 (also called STK3), MST3 (also called STK24), MST4, and YSK1 (also called STK25 or SOK1). MST kinases are emerging as key signaling molecules that influence cell proliferation, organ size, cell migration, and cell polarity. Here we review the regulation and function of these kinases in normal physiology and pathologies, including cancer, endothelial malformations, and autoimmune disease.
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Affiliation(s)
| | - Erik Sahai
- The Francis Crick Institute, London WC2A 3LY, England, UK
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Scarfone I, Venturetti M, Hotz M, Lengefeld J, Barral Y, Piatti S. Asymmetry of the budding yeast Tem1 GTPase at spindle poles is required for spindle positioning but not for mitotic exit. PLoS Genet 2015; 11:e1004938. [PMID: 25658911 PMCID: PMC4450052 DOI: 10.1371/journal.pgen.1004938] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 12/04/2014] [Indexed: 11/19/2022] Open
Abstract
The asymmetrically dividing yeast S. cerevisiae assembles a bipolar spindle well after establishing the future site of cell division (i.e., the bud neck) and the division axis (i.e., the mother-bud axis). A surveillance mechanism called spindle position checkpoint (SPOC) delays mitotic exit and cytokinesis until the spindle is properly positioned relative to the mother-bud axis, thereby ensuring the correct ploidy of the progeny. SPOC relies on the heterodimeric GTPase-activating protein Bub2/Bfa1 that inhibits the small GTPase Tem1, in turn essential for activating the mitotic exit network (MEN) kinase cascade and cytokinesis. The Bub2/Bfa1 GAP and the Tem1 GTPase form a complex at spindle poles that undergoes a remarkable asymmetry during mitosis when the spindle is properly positioned, with the complex accumulating on the bud-directed old spindle pole. In contrast, the complex remains symmetrically localized on both poles of misaligned spindles. The mechanism driving asymmetry of Bub2/Bfa1/Tem1 in mitosis is unclear. Furthermore, whether asymmetry is involved in timely mitotic exit is controversial. We investigated the mechanism by which the GAP Bub2/Bfa1 controls GTP hydrolysis on Tem1 and generated a series of mutants leading to constitutive Tem1 activation. These mutants are SPOC-defective and invariably lead to symmetrical localization of Bub2/Bfa1/Tem1 at spindle poles, indicating that GTP hydrolysis is essential for asymmetry. Constitutive tethering of Bub2 or Bfa1 to both spindle poles impairs SPOC response but does not impair mitotic exit. Rather, it facilitates mitotic exit of MEN mutants, likely by increasing the residence time of Tem1 at spindle poles where it gets active. Surprisingly, all mutant or chimeric proteins leading to symmetrical localization of Bub2/Bfa1/Tem1 lead to increased symmetry at spindle poles of the Kar9 protein that mediates spindle positioning and cause spindle misalignment. Thus, asymmetry of the Bub2/Bfa1/Tem1 complex is crucial to control Kar9 distribution and spindle positioning during mitosis.
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Affiliation(s)
- Ilaria Scarfone
- Centre de Recherche en Biochimie Macromoléculaire, Montpellier, France
- Dipartimento di Biotecnologie e Bioscienze Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Marianna Venturetti
- Dipartimento di Biotecnologie e Bioscienze Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Manuel Hotz
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | | | - Yves Barral
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Simonetta Piatti
- Centre de Recherche en Biochimie Macromoléculaire, Montpellier, France
- Dipartimento di Biotecnologie e Bioscienze Università degli Studi di Milano-Bicocca, Milano, Italy
- * E-mail:
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12
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Baro B, Rodriguez-Rodriguez JA, Calabria I, Hernáez ML, Gil C, Queralt E. Dual Regulation of the mitotic exit network (MEN) by PP2A-Cdc55 phosphatase. PLoS Genet 2013; 9:e1003966. [PMID: 24339788 PMCID: PMC3854864 DOI: 10.1371/journal.pgen.1003966] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 10/04/2013] [Indexed: 12/17/2022] Open
Abstract
Exit from mitosis in budding yeast is triggered by activation of the key mitotic phosphatase Cdc14. At anaphase onset, the protease separase and Zds1 promote the downregulation of PP2ACdc55 phosphatase, which facilitates Cdk1-dependent phosphorylation of Net1 and provides the first wave of Cdc14 activity. Once Cdk1 activity starts to decline, the mitotic exit network (MEN) is activated to achieve full Cdc14 activation. Here we describe how the PP2ACdc55 phosphatase could act as a functional link between FEAR and MEN due to its action on Bfa1 and Mob1. We demonstrate that PP2ACdc55 regulates MEN activation by facilitating Cdc5- and Cdk1-dependent phosphorylation of Bfa1 and Mob1, respectively. Downregulation of PP2ACdc55 initiates MEN activity up to Cdc15 by Bfa1 inactivation. Surprisingly, the premature Bfa1 inactivation observed does not entail premature MEN activation, since an additional Cdk1-Clb2 inhibitory signal acting towards Dbf2-Mob1 activity restrains MEN activity until anaphase. In conclusion, we propose a clear picture of how PP2ACdc55 functions affect the regulation of various MEN components, contributing to mitotic exit. Cell cycle studies over the years have tried to elucidate the molecular mechanisms behind cell division, one of the most highly regulated of all cell processes, which ensures life in all organisms. Protein phosphorylation emerged as a key regulatory mechanism in the cell cycle. The highly conserved family of cyclin-dependent kinases, the Cdks, are considered the main component of the cell cycle control system. However, it has become clear that opposing phosphatases also play a key role in determining the phosphorylation state of the proteins. Cells enter mitosis when mitotic Cdk activity increases, having its pick of activity during metaphase. To exit mitosis, cells must coordinate chromosome segregation with Cdk inactivation processes involving the activation of protein phosphatases. Here we show that the phosphatase PP2A regulates the mitotic exit network (MEN) by counteracting the phosphorylation of Bfa1 and Mob1. Our findings provide new insights into the mechanism by which PP2A-Cdc55 functions affect the regulation of various MEN components that contribute to mitotic exit. The core signalling elements of the MEN, SIN and Hippo pathways are highly conserved. Therefore, studies of MEN regulation will contribute to our understanding of MEN-related pathways in other organisms.
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Affiliation(s)
- Barbara Baro
- Cell Cycle Group, Cancer Epigenetics and Biology Program (PEBC), Institut d'Investigacions Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Jose-Antonio Rodriguez-Rodriguez
- Cell Cycle Group, Cancer Epigenetics and Biology Program (PEBC), Institut d'Investigacions Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Ines Calabria
- Cell Cycle Group, Cancer Epigenetics and Biology Program (PEBC), Institut d'Investigacions Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - María Luisa Hernáez
- Unidad de Proteómica, Parque Científico de Madrid, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Concha Gil
- Unidad de Proteómica, Parque Científico de Madrid, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Ethel Queralt
- Cell Cycle Group, Cancer Epigenetics and Biology Program (PEBC), Institut d'Investigacions Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
- * E-mail:
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Faust AME, Wong CCL, Yates III JR, Drubin DG, Barnes G. The FEAR protein Slk19 restricts Cdc14 phosphatase to the nucleus until the end of anaphase, regulating its participation in mitotic exit in Saccharomyces cerevisiae. PLoS One 2013; 8:e73194. [PMID: 24039885 PMCID: PMC3769316 DOI: 10.1371/journal.pone.0073194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 07/17/2013] [Indexed: 11/18/2022] Open
Abstract
In Saccharomyces cerevisiae mitosis, the protein Slk19 plays an important role in the initial release of Cdc14 phosphatase from the nucleolus to the nucleus in early anaphase, an event that is critical for proper anaphase progression. A role for Slk19 in later mitotic stages of Cdc14 regulation, however, has not been demonstrated. While investigating the role of Slk19 post-translational modification on Cdc14 regulation, we found that a triple point mutant of SLK19, slk19(3R) (three lysine-to-arginine mutations), strongly affects Cdc14 localization during late anaphase and mitotic exit. Using fluorescence live-cell microscopy, we found that, similar to slk19Δ cells, slk19(3R) cells exhibit no defect in spindle stability and only a mild defect in spindle elongation dynamics. Unlike slk19Δcells, however, slk19(3R) cells exhibit no defect in Cdc14 release from the nucleolus to the nucleus. Instead, slk19(3R) cells are defective in the timing of Cdc14 movement from the nucleus to the cytoplasm at the end of anaphase. This mutant has a novel phenotype: slk19(3R) causes premature Cdc14 movement to the cytoplasm prior to, rather than concomitant with, spindle disassembly. One consequence of this premature Cdc14 movement is the inappropriate activation of the mitotic exit network, made evident by the fact that slk19(3R) partially rescues a mutant of the mitotic exit network kinase Cdc15. In conclusion, in addition to its role in regulating Cdc14 release from the nucleolus to the nucleus, we found that Slk19 is also important for regulating Cdc14 movement from the nucleus to the cytoplasm at the end of anaphase.
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Affiliation(s)
- Ann Marie E. Faust
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Catherine C. L. Wong
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - John R. Yates III
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - David G. Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Georjana Barnes
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- * E-mail:
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14
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Cassani C, Raspelli E, Santo N, Chiroli E, Lucchini G, Fraschini R. Saccharomyces cerevisiae Dma proteins participate in cytokinesis by controlling two different pathways. Cell Cycle 2013; 12:2794-808. [PMID: 23966170 PMCID: PMC3899193 DOI: 10.4161/cc.25869] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Cytokinesis completion in the budding yeast S. cerevisiae is driven by tightly regulated pathways, leading to actomyosin ring contraction coupled to plasma membrane constriction and to centripetal growth of the primary septum, respectively. These pathways can partially substitute for each other, but their concomitant inactivation leads to cytokinesis block and cell death. Here we show that both the lack of the functionally redundant FHA-RING ubiquitin ligases Dma1 and Dma2 and moderate Dma2 overproduction affect actomyosin ring contraction as well as primary septum deposition, although they do not apparently alter cell cycle progression of otherwise wild-type cells. In addition, overproduction of Dma2 impairs the interaction between Tem1 and Iqg1, which is thought to be required for AMR contraction, and causes asymmetric primary septum deposition as well as mislocalization of the Cyk3-positive regulator of this process. In agreement with these multiple inhibitory effects, a Dma2 excess that does not cause any apparent defect in wild-type cells leads to lethal cytokinesis block in cells lacking the Hof1 protein, which is essential for primary septum formation in the absence of Cyk3. Altogether, these findings suggest that the Dma proteins act as negative regulators of cytokinesis.
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Affiliation(s)
- Corinne Cassani
- Università degli Studi di Milano-Bicocca; Dipartimento di Biotecnologie e Bioscienze; Milano, Italy
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15
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Sanchez-Diaz A, Nkosi PJ, Murray S, Labib K. The Mitotic Exit Network and Cdc14 phosphatase initiate cytokinesis by counteracting CDK phosphorylations and blocking polarised growth. EMBO J 2012; 31:3620-34. [PMID: 22872148 DOI: 10.1038/emboj.2012.224] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 07/17/2012] [Indexed: 01/27/2023] Open
Abstract
Polarisation of the actin cytoskeleton must cease during cytokinesis, to support efficient assembly and contraction of the actomyosin ring at the site of cell division, but the underlying mechanisms are still understood poorly in most species. In budding yeast, the Mitotic Exit Network (MEN) releases Cdc14 phosphatase from the nucleolus during anaphase, leading to the inactivation of mitotic forms of cyclin-dependent kinase (CDK) and the onset of septation, before G1-CDK can be reactivated and drive re-polarisation of the actin cytoskeleton to a new bud. Here, we show that premature inactivation of mitotic CDK, before release of Cdc14, allows G1-CDK to divert the actin cytoskeleton away from the actomyosin ring to a new site of polarised growth, thereby delaying progression through cytokinesis. Our data indicate that cells normally avoid this problem via the MEN-dependent release of Cdc14, which counteracts all classes of CDK-mediated phosphorylations during cytokinesis and blocks polarised growth. The dephosphorylation of CDK targets is therefore central to the mechanism by which the MEN and Cdc14 initiate cytokinesis and block polarised growth during late mitosis.
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Affiliation(s)
- Alberto Sanchez-Diaz
- Paterson Institute for Cancer Research, University of Manchester, Manchester, UK
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16
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Johnson AE, McCollum D, Gould KL. Polar opposites: Fine-tuning cytokinesis through SIN asymmetry. Cytoskeleton (Hoboken) 2012; 69:686-99. [PMID: 22786806 PMCID: PMC3478943 DOI: 10.1002/cm.21044] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 06/04/2012] [Indexed: 01/10/2023]
Abstract
Mitotic exit and cell division must be spatially and temporally integrated to facilitate equal division of genetic material between daughter cells. In the fission yeast, Schizosaccharomyces pombe, a spindle pole body (SPB) localized signaling cascade termed the septation initiation network (SIN) couples mitotic exit with cytokinesis. The SIN is controlled at many levels to ensure that cytokinesis is executed once per cell cycle and only after cells segregate their DNA. An interesting facet of the SIN is that its activity is asymmetric on the two SPBs during anaphase; however, how and why the SIN is asymmetric has remained elusive. Many key factors controlling SIN asymmetry have now been identified, shedding light on the significance of SIN asymmetry in regulating cytokinesis. In this review, we highlight recent advances in our understanding of SIN regulation, with an emphasis on how SIN asymmetry is achieved and how this aspect of SIN regulation fine-tunes cytokinesis.
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Affiliation(s)
- Alyssa E Johnson
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
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17
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Oh Y, Chang KJ, Orlean P, Wloka C, Deshaies R, Bi E. Mitotic exit kinase Dbf2 directly phosphorylates chitin synthase Chs2 to regulate cytokinesis in budding yeast. Mol Biol Cell 2012; 23:2445-56. [PMID: 22573892 PMCID: PMC3386209 DOI: 10.1091/mbc.e12-01-0033] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
How cell cycle machinery regulates extracellular matrix (ECM) remodeling during cytokinesis remains poorly understood. In the budding yeast Saccharomyces cerevisiae, the primary septum (PS), a functional equivalent of animal ECM, is synthesized during cytokinesis by the chitin synthase Chs2. Here, we report that Dbf2, a conserved mitotic exit kinase, localizes to the division site after Chs2 and directly phosphorylates Chs2 on several residues, including Ser-217. Both phosphodeficient (chs2-S217A) and phosphomimic (chs2-S217D) mutations cause defects in cytokinesis, suggesting that dynamic phosphorylation-dephosphorylation of Ser-217 is critical for Chs2 function. It is striking that Chs2-S217A constricts asymmetrically with the actomyosin ring (AMR), whereas Chs2-S217D displays little or no constriction and remains highly mobile at the division site. These data suggest that Chs2 phosphorylation by Dbf2 triggers its dissociation from the AMR during the late stage of cytokinesis. Of interest, both chs2-S217A and chs2-S217D mutants are robustly suppressed by increased dosage of Cyk3, a cytokinesis protein that displays Dbf2-dependent localization and also stimulates Chs2-mediated chitin synthesis. Thus Dbf2 regulates PS formation through at least two independent pathways: direct phosphorylation and Cyk3-mediated activation of Chs2. Our study establishes a mechanism for direct cell cycle control of ECM remodeling during cytokinesis.
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Affiliation(s)
- Younghoon Oh
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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18
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Abstract
Studies of the processes leading to the construction of a bud and its separation from the mother cell in Saccharomyces cerevisiae have provided foundational paradigms for the mechanisms of polarity establishment, cytoskeletal organization, and cytokinesis. Here we review our current understanding of how these morphogenetic events occur and how they are controlled by the cell-cycle-regulatory cyclin-CDK system. In addition, defects in morphogenesis provide signals that feed back on the cyclin-CDK system, and we review what is known regarding regulation of cell-cycle progression in response to such defects, primarily acting through the kinase Swe1p. The bidirectional communication between morphogenesis and the cell cycle is crucial for successful proliferation, and its study has illuminated many elegant and often unexpected regulatory mechanisms. Despite considerable progress, however, many of the most puzzling mysteries in this field remain to be resolved.
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Affiliation(s)
- Audrey S. Howell
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710
| | - Daniel J. Lew
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710
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19
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Jones MH, Keck JM, Wong CCL, Xu T, Yates JR, Winey M. Cell cycle phosphorylation of mitotic exit network (MEN) proteins. Cell Cycle 2011; 10:3435-40. [PMID: 22031224 DOI: 10.4161/cc.10.20.17790] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Phosphorylation of proteins is an important mechanism used to regulate most cellular processes. Recently, we completed an extensive phosphoproteomic analysis of the core proteins that constitute the Saccharomyces cerevisiae centrosome. Here, we present a study of phosphorylation sites found on the mitotic exit network (MEN) proteins, most of which are associated with the cytoplasmic face of the centrosome. We identified 55 sites on Bfa1, Cdc5, Cdc14 and Cdc15. Eight sites lie in cyclin-dependent kinase motifs (Cdk, S/T-P), and 22 sites are completely conserved within fungi. More than half of the sites were found in centrosomes from mitotic cells, possibly in preparation for their roles in mitotic exit. Finally, we report phosphorylation site information for other important cell cycle and regulatory proteins.
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20
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Caydasi AK, Ibrahim B, Pereira G. Monitoring spindle orientation: Spindle position checkpoint in charge. Cell Div 2010; 5:28. [PMID: 21143992 PMCID: PMC3004881 DOI: 10.1186/1747-1028-5-28] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 12/11/2010] [Indexed: 12/15/2022] Open
Abstract
Every cell division in budding yeast is inherently asymmetric and counts on the correct positioning of the mitotic spindle along the mother-daughter polarity axis for faithful chromosome segregation. A surveillance mechanism named the spindle position checkpoint (SPOC), monitors the orientation of the mitotic spindle and prevents cells from exiting mitosis when the spindle fails to align along the mother-daughter axis. SPOC is essential for maintenance of ploidy in budding yeast and similar mechanisms might exist in higher eukaryotes to ensure faithful asymmetric cell division. Here, we review the current model of SPOC activation and highlight the importance of protein localization and phosphorylation for SPOC function.
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Affiliation(s)
- Ayse K Caydasi
- German Cancer Research Centre, DKFZ-ZMBH Alliance, Molecular Biology of Centrosomes and Cilia, Im Neuenheimer Feld 581, 69120 Heidelberg, Germany.
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21
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Peraza-Reyes L, Crider DG, Pon LA. Mitochondrial manoeuvres: latest insights and hypotheses on mitochondrial partitioning during mitosis in Saccharomyces cerevisiae. Bioessays 2010; 32:1040-9. [PMID: 20886527 DOI: 10.1002/bies.201000083] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 08/19/2010] [Accepted: 08/24/2010] [Indexed: 12/22/2022]
Abstract
Movement and positional control of mitochondria and other organelles are coordinated with cell cycle progression in the budding yeast, Saccharomyces cerevisiae. Recent studies have revealed a checkpoint that inhibits cytokinesis when there are severe defects in mitochondrial inheritance. An established checkpoint signaling pathway, the mitotic exit network (MEN), participates in this process. Here, we describe mitochondrial motility during inheritance in budding yeast, emerging evidence for mitochondrial quality control during inheritance, and organelle inheritance checkpoints for mitochondria and other organelles.
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Affiliation(s)
- Leonardo Peraza-Reyes
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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22
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Meitinger F, Petrova B, Lombardi IM, Bertazzi DT, Hub B, Zentgraf H, Pereira G. Targeted localization of Inn1, Cyk3 and Chs2 by the mitotic-exit network regulates cytokinesis in budding yeast. J Cell Sci 2010; 123:1851-61. [PMID: 20442249 DOI: 10.1242/jcs.063891] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The mitotic-exit network (MEN) is a signaling pathway that is essential for the coordination of mitotic exit and cytokinesis. Whereas the role of the MEN in mitotic exit is well established, the molecular mechanisms by which MEN components regulate cytokinesis remain poorly understood. Here, we show that the MEN controls components involved in septum formation, including Inn1, Cyk3 and Chs2. MEN-deficient mutants, forced to exit mitosis as a result of Cdk1 inactivation, show defects in targeting Cyk3 and Inn1 to the bud-neck region. In addition, we found that the chitin synthase Chs2 did not efficiently localize at the bud neck in the absence of MEN activity. Ultrastructural analysis of the bud neck revealed that low MEN activity led to unilateral, uncoordinated extension of the primary and secondary septa. This defect was partially suppressed by increased levels of Cyk3. We therefore propose that the MEN directly controls cytokinesis via targeting of Inn1, Cyk3 and Chs2 to the bud neck.
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Affiliation(s)
- Franz Meitinger
- German Cancer Research Centre, DKFZ-ZMBH Alliance, Molecular Biology of Centrosomes and Cilia Unit, Im Neuenheimer Feld 581, 69120 Heidelberg, Germany
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23
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Lu Y, Cross FR. Periodic cyclin-Cdk activity entrains an autonomous Cdc14 release oscillator. Cell 2010; 141:268-79. [PMID: 20403323 DOI: 10.1016/j.cell.2010.03.021] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 12/24/2009] [Accepted: 03/17/2010] [Indexed: 12/22/2022]
Abstract
One oscillation of Cyclin-dependent kinase (Cdk) activity, largely driven by periodic synthesis and destruction of cyclins, is tightly coupled to a single complete eukaryotic cell division cycle. Tight linkage of different steps in diverse cell-cycle processes to Cdk activity has been proposed to explain this coupling. Here, we demonstrate an intrinsically oscillatory module controlling nucleolar release and resequestration of the Cdc14 phosphatase, which is essential for mitotic exit in budding yeast. We find that this Cdc14 release oscillator functions at constant and physiological cyclin-Cdk levels, and is therefore independent of the Cdk oscillator. However, the frequency of the release oscillator is regulated by cyclin-Cdk activity. This observation together with its mechanism suggests that the intrinsically autonomous Cdc14 release cycles are locked at once-per-cell-cycle through entrainment by the Cdk oscillator in wild-type cells. This concept may have broad implications for the structure and evolution of eukaryotic cell-cycle control.
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Affiliation(s)
- Ying Lu
- The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
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24
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König C, Maekawa H, Schiebel E. Mutual regulation of cyclin-dependent kinase and the mitotic exit network. ACTA ACUST UNITED AC 2010; 188:351-68. [PMID: 20123997 PMCID: PMC2819678 DOI: 10.1083/jcb.200911128] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
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.
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Affiliation(s)
- Cornelia König
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), ZMBH-DKFZ Alliance, 69120 Heidelberg, Germany
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25
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Park SY, Cable AE, Blair J, Stockstill KE, Shannnon KB. Bub2 regulation of cytokinesis and septation in budding yeast. BMC Cell Biol 2009; 10:43. [PMID: 19490645 PMCID: PMC2701927 DOI: 10.1186/1471-2121-10-43] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Accepted: 06/02/2009] [Indexed: 11/17/2022] Open
Abstract
Background The mitotic exit network (MEN) is required for events at the end of mitosis such as degradation of mitotic cyclins and cytokinesis. Bub2 and its binding partner Bfa1 act as a GTPase activating protein (GAP) to negatively regulate the MEN GTPase Tem1. The Bub2/Bfa1 checkpoint pathway is required to delay the cell cycle in response to mispositioned spindles. In addition to its role in mitotic exit, Tem1 is required for actomyosin ring contraction. Results To test the hypothesis that the Bub2 pathway prevents premature actin ring assembly, we compared the timing of actin ring formation in wild type, bub2Δ, mad2Δ, and bub2Δmad2Δ cells both with and without microtubules. There was no difference in the timing of actin ring formation between wild type and mutant cells in a synchronized cell cycle. In the presence of nocodazole, both bub2Δ and mad2Δ cells formed rings after a delay of the same duration. Double mutant bub2Δmad2Δ and bfa1Δmad2Δ cells formed rings at the same time with and without nocodazole. To determine if Bub2 has an effect on actomyosin ring contraction through its regulation of Tem1, we used live cell imaging of Myo1-GFP in a bub2Δ strain. We found a significant decrease in the total time of contraction and an increase in rate of contraction compared to wild type cells. We also examined myosin contraction using Myo1-GFP in cells overexpressing an epitope tagged Bub2. Surprisingly, overexpression of Bub2 also led to a significant increase in the rate of contraction, as well as morphological defects. The chained cell phenotype caused by Bub2 overexpression could be rescued by co-overexpression of Tem1, and was not rescued by deletion of BFA1. Conclusion Our data indicate that the Bub2 checkpoint pathway does not have a specific role in delaying actin ring formation. The observed increase in the rate of myosin contraction in the bub2Δ strain provides evidence that the MEN regulates actomyosin ring contraction. Our data suggest that the overexpression of the Bub2 fusion protein acts as a dominant negative, leading to septation defects by a mechanism that is Tem1-dependent.
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Affiliation(s)
- Su Young Park
- Department of Biological Sciences, Missouri University of Science and Technology, Rolla, MO, USA.
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26
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Amon A. A decade of Cdc14--a personal perspective. Delivered on 9 July 2007 at the 32nd FEBS Congress in Vienna, Austria. FEBS J 2009; 275:5774-84. [PMID: 19021755 DOI: 10.1111/j.1742-4658.2008.06693.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In budding yeast, the protein phosphatase Cdc14 is a key regulator of late mitotic events. Research over the last decade has revealed many of its functions and today we know that this protein phosphatase orchestrates several aspects of chromosome segregation and is the key trigger of exit from mitosis. Elucidation of the mechanisms controlling Cdc14 activity through nucleolar sequestration now serves as a paradigm for how regulation of the subcellular localization of proteins regulates protein function. Here I review these findings focusing on how discoveries in my laboratory helped elucidate the function and regulation of Cdc14.
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Affiliation(s)
- Angelika Amon
- David H. Koch Institute for Integrative Cancer Research, Cambridge, MA, USA.
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27
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Peng Y, Weisman LS. The cyclin-dependent kinase Cdk1 directly regulates vacuole inheritance. Dev Cell 2008; 15:478-485. [PMID: 18804442 DOI: 10.1016/j.devcel.2008.07.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2007] [Revised: 04/04/2008] [Accepted: 07/14/2008] [Indexed: 11/24/2022]
Abstract
In budding yeast, vacuole inheritance is tightly coordinated with the cell cycle. The movement of vacuoles and several other organelles is actin-based and is mediated by interaction between the yeast myosin V motor Myo2 and organelle-specific adaptors. Myo2 binds to vacuoles via the adaptor protein Vac17, which binds to the vacuole membrane protein Vac8. Here we show that the yeast cyclin-dependent kinase Cdk1 phosphorylates Vac17 and that phosphorylation of Vac17 parallels cell cycle-dependent movement of the vacuole. Substitution of the Cdk1 sites in Vac17 decreases its interaction with Myo2 and causes a partial defect in vacuole inheritance. This defect is enhanced in the presence of Myo2 with mutated phosphorylation sites. Thus, Cdk1 appears to control the timing of vacuole movement. The presence of multiple predicted Cdk1 sites in other organelle-specific myosin V adaptors suggests that the inheritance of other cytoplasmic organelles may be regulated by a similar mechanism.
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Affiliation(s)
- Yutian Peng
- Department of Cell & Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Lois S Weisman
- Department of Cell & Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
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28
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Pablo-Hernando ME, Arnaiz-Pita Y, Nakanishi H, Dawson D, del Rey F, Neiman AM, Vázquez de Aldana CR. Cdc15 is required for spore morphogenesis independently of Cdc14 in Saccharomyces cerevisiae. Genetics 2007; 177:281-93. [PMID: 17660551 PMCID: PMC2013696 DOI: 10.1534/genetics.107.076133] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Saccharomyces cerevisiae exit from mitosis requires the Cdc14 phosphatase to reverse CDK-mediated phosphorylation. Cdc14 is released from the nucleolus by the Cdc14 early anaphase release (FEAR) and mitotic exit network (MEN) pathways. In meiosis, the FEAR pathway is essential for exit from anaphase I. The MEN component Cdc15 is required for the formation of mature spores. To analyze the role of Cdc15 during sporulation, a conditional mutant in which CDC15 expression was controlled by the CLB2 promoter was used. Cdc15-depleted cells proceeded normally through the meiotic divisions but were unable to properly disassemble meiosis II spindles. The morphology of the prospore membrane was aberrant and failed to capture the nuclear lobes. Cdc15 was not required for Cdc14 release from the nucleoli, but it was essential to maintain Cdc14 released and for its nucleo-cytoplasmic transport. However, cells carrying a CDC14 allele with defects in nuclear export (Cdc14-DeltaNES) were able to disassemble the spindle and to complete spore formation, suggesting that the Cdc14 nuclear export defect was not the cause of the phenotypes observed in cdc15 mutants.
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Affiliation(s)
- M Evangelina Pablo-Hernando
- Instituto de Microbiología Bioquímica, Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, 37007 Salamanca, Spain
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29
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Rubenstein EM, Schmidt MC. Mechanisms regulating the protein kinases of Saccharomyces cerevisiae. EUKARYOTIC CELL 2007; 6:571-83. [PMID: 17337635 PMCID: PMC1865659 DOI: 10.1128/ec.00026-07] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Eric M Rubenstein
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, W1247 Biomedical Science Tower, Pittsburgh, PA 15261, USA
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30
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Park HO, Bi E. Central roles of small GTPases in the development of cell polarity in yeast and beyond. Microbiol Mol Biol Rev 2007; 71:48-96. [PMID: 17347519 PMCID: PMC1847380 DOI: 10.1128/mmbr.00028-06] [Citation(s) in RCA: 323] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
SUMMARY The establishment of cell polarity is critical for the development of many organisms and for the function of many cell types. A large number of studies of diverse organisms from yeast to humans indicate that the conserved, small-molecular-weight GTPases function as key signaling proteins involved in cell polarization. The budding yeast Saccharomyces cerevisiae is a particularly attractive model because it displays pronounced cell polarity in response to intracellular and extracellular cues. Cells of S. cerevisiae undergo polarized growth during various phases of their life cycle, such as during vegetative growth, mating between haploid cells of opposite mating types, and filamentous growth upon deprivation of nutrition such as nitrogen. Substantial progress has been made in deciphering the molecular basis of cell polarity in budding yeast. In particular, it becomes increasingly clear how small GTPases regulate polarized cytoskeletal organization, cell wall assembly, and exocytosis at the molecular level and how these GTPases are regulated. In this review, we discuss the key signaling pathways that regulate cell polarization during the mitotic cell cycle and during mating.
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Affiliation(s)
- Hay-Oak Park
- Department of Molecular Genetics, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA.
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31
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Corbett M, Xiong Y, Boyne JR, Wright DJ, Munro E, Price C. IQGAP and mitotic exit network (MEN) proteins are required for cytokinesis and re-polarization of the actin cytoskeleton in the budding yeast, Saccharomyces cerevisiae. Eur J Cell Biol 2006; 85:1201-15. [PMID: 17005296 DOI: 10.1016/j.ejcb.2006.08.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 08/04/2006] [Accepted: 08/04/2006] [Indexed: 11/21/2022] Open
Abstract
In budding yeast the final stages of the cell division cycle, cytokinesis and cell separation, are distinct events that require to be coupled, both together and with mitotic exit. Here we demonstrate that mutations in genes of the mitotic exit network (MEN) prevent cell separation and are synthetically lethal in combination with both cytokinesis and septation defective mutations. Analysis of the synthetic lethal phenotypes reveals that Iqg1p functions in combination with the MEN components, Tem1p, Cdc15p Dbf20p and Dbf2p to govern the re-polarization of the actin cytoskeleton to either side of the bud neck. In addition phosphorylation of the conserved PCH protein, Hof1p, is dependent upon these activities and requires actin ring assembly. Recruitment of Dbf2p to the bud neck is dependent upon actin ring assembly and correlates with Hof1p phosphorylation. Failure to phosphorylate Hof1p results in the increased stability of the protein and its persistence at the bud neck. These data establish a mechanistic dependency of cell separation upon an intermediate step requiring actomyosin ring assembly.
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Affiliation(s)
- Mark Corbett
- Biological Sciences, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
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32
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Piatti S, Venturetti M, Chiroli E, Fraschini R. The spindle position checkpoint in budding yeast: the motherly care of MEN. Cell Div 2006; 1:2. [PMID: 16759408 PMCID: PMC1459270 DOI: 10.1186/1747-1028-1-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Accepted: 04/03/2006] [Indexed: 11/10/2022] Open
Abstract
Mitotic exit and cytokinesis must be tightly coupled to nuclear division both in time and space in order to preserve genome stability and to ensure that daughter cells inherit the right set of chromosomes after cell division. This is achieved in budding yeast through control over a signal transduction cascade, the mitotic exit network (MEN), which is required for mitotic CDK inactivation in telophase and for cytokinesis. Current models of MEN activation emphasize on the bud as the place where most control is exerted. This review focuses on recent data that instead point to the mother cell as being the residence of key regulators of late mitotic events.
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Affiliation(s)
- Simonetta Piatti
- Dipartimento di Biotecnologie e Bioscienze, Universita' di Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | - Marianna Venturetti
- Dipartimento di Biotecnologie e Bioscienze, Universita' di Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | - Elena Chiroli
- Dipartimento di Biotecnologie e Bioscienze, Universita' di Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | - Roberta Fraschini
- Dipartimento di Biotecnologie e Bioscienze, Universita' di Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
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33
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Hergovich A, Stegert MR, Schmitz D, Hemmings BA. NDR kinases regulate essential cell processes from yeast to humans. Nat Rev Mol Cell Biol 2006; 7:253-64. [PMID: 16607288 DOI: 10.1038/nrm1891] [Citation(s) in RCA: 259] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Members of the NDR (nuclear Dbf2-related) protein-kinase family are essential components of pathways that control important cellular processes, such as morphological changes, mitotic exit, cytokinesis, cell proliferation and apoptosis. Recent progress has shed light on the mechanisms that underlie the regulation and function of the NDR family members. Combined data from yeast, worms, flies, mice and human cells now highlight the conserved and important roles of the different NDR kinases in distinct cellular processes.
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Affiliation(s)
- Alexander Hergovich
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
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34
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Clemente-Blanco A, González-Novo A, Machín F, Caballero-Lima D, Aragón L, Sánchez M, de Aldana CRV, Jiménez J, Correa-Bordes J. The Cdc14p phosphatase affects late cell-cycle events and morphogenesis inCandida albicans. J Cell Sci 2006; 119:1130-43. [PMID: 16507592 DOI: 10.1242/jcs.02820] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
We have characterized the CDC14 gene, which encodes a dual-specificity protein phosphatase in Candida albicans, and demonstrated that its deletion results in defects in cell separation, mitotic exit and morphogenesis. The C. albicans cdc14Δ mutants formed large aggregates of cells that resembled those found in ace2-null strains. In cdc14Δ cells, expression of Ace2p target genes was reduced and Ace2p did not accumulate specifically in daughter nuclei. Taken together, these results imply that Cdc14p is required for the activation and daughter-specific nuclear accumulation of Ace2p. Consistent with a role in cell separation, Cdc14p was targeted to the septum region during the M-G1 transition in yeast-form cells. Interestingly, hypha-inducing signals abolished the translocation of Cdc14p to the division plate, and this regulation depended on the cyclin Hgc1p, since hgc1Δ mutants were able to accumulate Cdc14p in the septum region of the germ tubes. In addition to its role in cytokinesis, Cdc14p regulated mitotic exit, since synchronous cultures of cdc14Δ cells exhibited a severe delay in the destruction of the mitotic cyclin Clb2p. Finally, deletion of CDC14 resulted in decreased invasion of solid agar medium and impaired true hyphal growth.
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Affiliation(s)
- Andrés Clemente-Blanco
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Extremadura, Avda Elvas SN, 06071, Badajoz, Spain
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35
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Abstract
Centrosomes, spindle pole bodies, and related structures in other organisms are a morphologically diverse group of organelles that share a common ability to nucleate and organize microtubules and are thus referred to as microtubule organizing centers or MTOCs. Features associated with MTOCs include organization of mitotic spindles, formation of primary cilia, progression through cytokinesis, and self-duplication once per cell cycle. Centrosomes bind more than 100 regulatory proteins, whose identities suggest roles in a multitude of cellular functions. In fact, recent work has shown that MTOCs are required for several regulatory functions including cell cycle transitions, cellular responses to stress, and organization of signal transduction pathways. These new liaisons between MTOCs and cellular regulation are the focus of this review. Elucidation of these and other previously unappreciated centrosome functions promises to yield exciting scientific discovery for some time to come.
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Affiliation(s)
- Stephen Doxsey
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
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36
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Mah AS, Elia AEH, Devgan G, Ptacek J, Schutkowski M, Snyder M, Yaffe MB, Deshaies RJ. Substrate specificity analysis of protein kinase complex Dbf2-Mob1 by peptide library and proteome array screening. BMC BIOCHEMISTRY 2005; 6:22. [PMID: 16242037 PMCID: PMC1277818 DOI: 10.1186/1471-2091-6-22] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2005] [Accepted: 10/21/2005] [Indexed: 11/10/2022]
Abstract
Background The mitotic exit network (MEN) is a group of proteins that form a signaling cascade that is essential for cells to exit mitosis in Saccharomyces cerevisiae. The MEN has also been implicated in playing a role in cytokinesis. Two components of this signaling pathway are the protein kinase Dbf2 and its binding partner essential for its kinase activity, Mob1. The components of MEN that act upstream of Dbf2-Mob1 have been characterized, but physiological substrates for Dbf2-Mob1 have yet to be identified. Results Using a combination of peptide library selection, phosphorylation of opitmal peptide variants, and screening of a phosphosite array, we found that Dbf2-Mob1 preferentially phosphorylated serine over threonine and required an arginine three residues upstream of the phosphorylated serine in its substrate. This requirement for arginine in peptide substrates could not be substituted with the similarly charged lysine. This specificity determined for peptide substrates was also evident in many of the proteins phosphorylated by Dbf2-Mob1 in a proteome chip analysis. Conclusion We have determined by peptide library selection and phosphosite array screening that the protein kinase Dbf2-Mob1 preferentially phosphorylated substrates that contain an RXXS motif. A subsequent proteome microarray screen revealed proteins that can be phosphorylated by Dbf2-Mob1 in vitro. These proteins are enriched for RXXS motifs, and may include substrates that mediate the function of Dbf2-Mob1 in mitotic exit and cytokinesis. The relatively low degree of sequence restriction at the site of phosphorylation suggests that Dbf2 achieves specificity by docking its substrates at a site that is distinct from the phosphorylation site
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Affiliation(s)
- Angie S Mah
- Department of Biology, California Institute of Technology, Pasadena, CA 91125, USA
| | - Andrew EH Elia
- Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Geeta Devgan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Jason Ptacek
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Mike Schutkowski
- JPT Peptide Technologies GmbH, Invalidenstrasse 130, 10115 Berlin, Germany, USA
| | - Michael Snyder
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Michael B Yaffe
- Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Raymond J Deshaies
- Department of Biology, California Institute of Technology, Pasadena, CA 91125, USA
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
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37
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Abstract
Completion of the cell cycle requires the temporal and spatial coordination of chromosome segregation with mitotic spindle disassembly and cytokinesis. In budding yeast, the protein phosphatase Cdc14 is a key regulator of these late mitotic events. Here, we review the functions of Cdc14 and how this phosphatase is regulated to accomplish the coupling of mitotic processes. We also discuss the function and regulation of Cdc14 in other eukaryotes, emphasizing conserved features.
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Affiliation(s)
- Frank Stegmeier
- Center for Cancer Research, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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38
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Lee KS, Park JE, Asano S, Park CJ. Yeast polo-like kinases: functionally conserved multitask mitotic regulators. Oncogene 2005; 24:217-29. [PMID: 15640837 DOI: 10.1038/sj.onc.1208271] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The polo-like kinases (Plks) are a conserved subfamily of Ser/Thr protein kinases that play pivotal roles in regulating various cellular and biochemical events at multiple stages of M phase. Genetic and biochemical data revealed that both the budding yeast and the fission yeast polo kinase homologs (Cdc5 and Plo1, respectively) bear remarkable functional similarities with those in metazoan organisms, suggesting that the role of Plks is largely conserved throughout evolution. Thus, studies on Plks in genetically amenable lower eucaryotic organisms may yield valuable insights into the function of Plks in higher eucaryotic organisms. In this review, common properties and distinct functions of Cdc5 and Plo1 will be discussed and compared to properties and functions of Plks in higher eucaryotic organisms.
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Affiliation(s)
- Kyung S Lee
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, NIH, 9000 Rockville Pike, Bldg 37, Rm 3118, Bethesda, MD 20892, USA.
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39
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Trautmann S, Rajagopalan S, McCollum D. The S. pombe Cdc14-like phosphatase Clp1p regulates chromosome biorientation and interacts with Aurora kinase. Dev Cell 2004; 7:755-62. [PMID: 15525536 DOI: 10.1016/j.devcel.2004.10.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 10/08/2004] [Accepted: 10/15/2004] [Indexed: 11/19/2022]
Abstract
The S. pombe Cdc14-related phosphatase Clp1p/Flp1p regulates G2/M transition by antagonizing CDK activity and is essential for coordinating the nuclear division cycle with cytokinesis through the cytokinesis checkpoint. At the G2/M transition, Clp1p/Flp1p is released from the nucleolus and SPB and distributes throughout the nucleus to the spindle and the contractile ring. This early relocalization is analogous to vertebrate Cdc14 homologs and stands in contrast to S. cerevisiae Cdc14p, which is not released from the nucleolus until metaphase/anaphase transition. Here, we report that Clp1p/Flp1p localizes to kinetochores in prometaphase and functions in chromosome segregation, since deletion of clp1/flp1 causes cosegregation of sister chromatids, when sister kinetochores are prone to mono-orientation. Genetic, cytological, and biochemical experiments suggest that Clp1p/Flp1p functions together with Aurora kinase at kinetochores. Together, these results suggest that Clp1p/Flp1p has a role in repairing mono-orientation of sister kinetochores.
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Affiliation(s)
- Susanne Trautmann
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical Center, Worcester, MA 01605, USA
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40
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Morrell JL, Tomlin GC, Rajagopalan S, Venkatram S, Feoktistova AS, Tasto JJ, Mehta S, Jennings JL, Link A, Balasubramanian MK, Gould KL. Sid4p-Cdc11p assembles the septation initiation network and its regulators at the S. pombe SPB. Curr Biol 2004; 14:579-84. [PMID: 15062098 DOI: 10.1016/j.cub.2004.03.036] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2003] [Revised: 01/19/2004] [Accepted: 02/10/2004] [Indexed: 10/26/2022]
Abstract
The Schizosaccharomyces pombe septation initiation network (SIN) triggers actomyosin ring constriction, septation, and cell division. It is organized at the spindle pole body (SPB) by the scaffold proteins Sid4p and Cdc11p. Here, we dissect the contributions of Sid4p and Cdc11p in anchoring SIN components and SIN regulators to the SPB. We find that Sid4p interacts with the SIN activator, Plo1p, in addition to Cdc11p and Dma1p. While the C terminus of Cdc11p is involved in binding Sid4p, its N-terminal half is involved in a wide variety of direct protein-protein interactions, including those with Spg1p, Sid2p, Cdc16p, and Cdk1p-Cdc13p. Given that the localizations of the remaining SIN components depend on Spg1p or Cdc16p, these data allow us to build a comprehensive model of SIN component organization at the SPB. FRAP experiments indicate that Sid4p and Cdc11p are stable SPB components, whereas signaling components of the SIN are dynamically associated with these structures. Our results suggest that the Sid4p-Cdc11p complex organizes a signaling hub on the SPB and that this hub coordinates cell and nuclear division.
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Affiliation(s)
- Jennifer L Morrell
- Howard Hughes Medical Institute and Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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41
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Abstract
The mitotic spindle segregates chromosomes to opposite ends of the cell in preparation for cell division. Chromosome attachment to the spindle is monitored by the spindle assembly checkpoint, and at least in yeast cells, penetration of one spindle pole into the bud is monitored by the spindle position checkpoint. We review the historical origins of these checkpoints and recent progress in understanding their surveillance pathways. We also highlight fascinating but as yet unresolved questions, and examine crosstalk between the checkpoints.
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Affiliation(s)
- Daniel J Lew
- Department of Pharmacology and Cancer Biology, Box 3813, Duke University Medical Center, Durham, North Carolina 27710, USA.
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42
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Abstract
Establishing the temporal order of mitotic events is critical to ensure that each daughter cell receives a complete DNA complement. The spatial co-ordination of the cytokinetic ring site with the axis of chromosome segregation is likewise crucial. Recent studies in fungi indicate that regulators of chromosome segregation also participate in promoting mitotic exit and that the proteins that initiate mitotic exit, in turn, additionally regulate cytokinesis. These findings suggest that late mitotic events are coupled by employing one pathway to control multiple events. The regulatory mechanisms that ensure the spatial co-ordination of the mitotic spindle apparatus with the division site have also been elucidated recently in the asymmetrically dividing budding yeast. Interestingly, the spatial co-ordination of late mitotic events seems also to be important in higher eukaryotes.
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Affiliation(s)
- Anupama Seshan
- Center for Cancer Research, Howard Hughes Medical Institute, Massachusetts Institute of Technology, E17-233, 40 Ames Street, Cambridge MA 02139, USA
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43
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Champion A, Kreis M, Mockaitis K, Picaud A, Henry Y. Arabidopsis kinome: after the casting. Funct Integr Genomics 2004; 4:163-87. [PMID: 14740254 DOI: 10.1007/s10142-003-0096-4] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2003] [Revised: 09/22/2003] [Accepted: 11/04/2003] [Indexed: 11/25/2022]
Abstract
Arabidopsis thaliana is used as a favourite experimental organism for many aspects of plant biology. We capitalized on the recently available Arabidopsis genome sequence and predicted proteome, to draw up a genome-scale protein serine/threonine kinase (PSTK) inventory. The PSTKs represent about 4% of the A. thaliana proteome. In this study, we provide a description of the content and diversity of the non-receptor PSTKs. These kinases have crucial functions in sensing, mediating and coordinating cellular responses to an extensive range of stimuli. A total of 369 predicted non receptor PSTKs were detailed: the Raf superfamily, the CMGC, CaMK, AGC and STE families, as well as a few small clades and orphan sequences. An extensive relationship analysis of these kinases allows us to classify the proteins in superfamilies, families, sub-families and groups. The classification provides a better knowledge of the characteristics shared by the different clades. We focused on the MAP kinase module elements, with particular attention to their docking sites for protein-protein interaction and their biological function. The large number of A. thaliana genes encoding kinases might have been achieved through successive rounds of gene and genome duplications. The evolution towards an increasing gene number suggests that functional redundancy plays an important role in plant genetic robustness.
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Affiliation(s)
- A Champion
- Institut de Biotechnologie des Plantes, Laboratoire de Biologie du Développement des Plantes, Bâtiment 630, UMR CNRS/UPS 8618, Université de Paris-Sud, 91405, Orsay Cedex, France
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44
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Hwa Lim H, Yeong FM, Surana U. Inactivation of mitotic kinase triggers translocation of MEN components to mother-daughter neck in yeast. Mol Biol Cell 2003; 14:4734-43. [PMID: 12937277 PMCID: PMC266787 DOI: 10.1091/mbc.e03-04-0238] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Chromosome segregation, mitotic exit, and cytokinesis are executed in this order during mitosis. Although a scheme coordinating sister chromatid separation and initiation of mitotic exit has been proposed, the mechanism that temporally links the onset of cytokinesis to mitotic exit is not known. Exit from mitosis is regulated by the mitotic exit network (MEN), which includes a GTPase (Tem1) and various kinases (Cdc15, Cdc5, Dbf2, and Dbf20). Here, we show that Dbf2 and Dbf20 functions are necessary for the execution of cytokinesis. Relocalization of these proteins from spindle pole bodies to mother daughter neck seems to be necessary for this role because cdc15-2 mutant cells, though capable of exiting mitosis at semipermissive temperature, are unable to localize Dbf2 (and Dbf20) to the "neck" and fail to undergo cytokinesis. These cells can assemble and constrict the actomyosin ring normally but are incapable of forming a septum, suggesting that MEN components are critical for the initiation of septum formation. Interestingly, the spindle pole body to neck translocation of Dbf2 and Dbf20 is triggered by the inactivation of mitotic kinase. The requirement of kinase inactivation for translocation of MEN components to the division site thus provides a mechanism that renders mitotic exit a prerequisite for cytokinesis.
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Affiliation(s)
- Hong Hwa Lim
- Institute of Molecular and Cell Biology, Singapore 117609
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45
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Yoder TJ, Pearson CG, Bloom K, Davis TN. The Saccharomyces cerevisiae spindle pole body is a dynamic structure. Mol Biol Cell 2003; 14:3494-505. [PMID: 12925780 PMCID: PMC181584 DOI: 10.1091/mbc.e02-10-0655] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2002] [Revised: 04/02/2003] [Accepted: 04/02/2003] [Indexed: 11/11/2022] Open
Abstract
During spindle pole body (SPB) duplication, the new SPB is assembled at a distinct site adjacent to the old SPB. Using quantitative fluorescence methods, we studied the assembly and dynamics of the core structural SPB component Spc110p. The SPB core exhibits both exchange and growth in a cell cycle-dependent manner. During G1/S phase, the old SPB exchanges approximately 50% of old Spc110p for new Spc110p. In G2 little Spc110p is exchangeable. Thus, Spc110p is dynamic during G1/S and becomes stable during G2. The SPB incorporates additional Spc110p in late G2 and M phases; this growth is followed by reduction in the next G1. Spc110p addition to the SPBs (growth) also occurs in response to G2 and mitotic arrests but not during a G1 arrest. Our results reveal several dynamic features of the SPB core: cell cycle-dependent growth and reduction, growth in response to cell cycle arrests, and exchange of Spc110p during SPB duplication. Moreover, rather than being considered a conservative or dispersive process, the assembly of Spc110p into the SPB is more readily considered in terms of growth and exchange.
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Affiliation(s)
- Tennessee J Yoder
- Program in Molecular and Cellular Biology, University of Washington, Seattle, Washington 98195, USA
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46
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Bardin AJ, Boselli MG, Amon A. Mitotic exit regulation through distinct domains within the protein kinase Cdc15. Mol Cell Biol 2003; 23:5018-30. [PMID: 12832486 PMCID: PMC162228 DOI: 10.1128/mcb.23.14.5018-5030.2003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mitotic exit network (MEN), a Ras-like signaling cascade, promotes the release of the protein phosphatase Cdc14 from the nucleolus and is essential for cells to exit from mitosis in Saccharomyces cerevisiae. We have characterized the functional domains of one of the MEN components, the protein kinase Cdc15, and investigated the role of these domains in mitotic exit. We show that a region adjacent to Cdc15's kinase domain is required for self-association and for binding to spindle pole bodies and that this domain is essential for CDC15 function. Furthermore, we find that overexpression of CDC15 lacking the C-terminal 224 amino acids results in hyperactivation of MEN and premature release of Cdc14 from the nucleolus, suggesting that this domain within Cdc15 functions to inhibit MEN signaling. Our findings indicate that multiple modes of MEN regulation occur through the protein kinase Cdc15.
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Affiliation(s)
- Allison J Bardin
- Center for Cancer Research, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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47
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Abstract
The Cdc14 phosphatase was identified by its requirement for mitotic exit in budding yeast. Cdc14 homologs exist throughout the eukaryotic kingdom, but it was unclear whether their function would also be conserved. Recent analyses in fission yeast, humans and now C. elegans suggest numerous other functions for this family of proteins.
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Affiliation(s)
- Susanne Trautmann
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical Center, 377 Plantation Street, Worcester, MA 01605, USA
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48
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Cid VCJ, Jiménez J, Molina MA, Sánchez M, Nombela C, Thorner JW. Orchestrating the cell cycle in yeast: sequential localization of key mitotic regulators at the spindle pole and the bud neck. MICROBIOLOGY (READING, ENGLAND) 2002; 148:2647-2659. [PMID: 12213912 DOI: 10.1099/00221287-148-9-2647] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Vı Ctor J Cid
- Departamento de Microbiologı́a II, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain1
| | - Javier Jiménez
- Departamento de Microbiologı́a y Genética, Instituto de Microbiologı́a-Bioquı́mica, Edificio Departamental, Campus Miguel de Unamuno, Universidad de Salamanca/CSIC, 37007 Salamanca, Spain2
| | - Marı A Molina
- Departamento de Microbiologı́a II, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain1
| | - Miguel Sánchez
- Departamento de Microbiologı́a y Genética, Instituto de Microbiologı́a-Bioquı́mica, Edificio Departamental, Campus Miguel de Unamuno, Universidad de Salamanca/CSIC, 37007 Salamanca, Spain2
| | - César Nombela
- Departamento de Microbiologı́a II, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain1
| | - Jeremy W Thorner
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720, USA3
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49
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Yeong FM, Lim HH, Surana U. MEN, destruction and separation: mechanistic links between mitotic exit and cytokinesis in budding yeast. Bioessays 2002; 24:659-66. [PMID: 12111726 DOI: 10.1002/bies.10106] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Cellular events must be executed in a certain sequence during the cell division in order to maintain genome integrity and hence ensure a cell's survival. In M phase, for instance, chromosome segregation always precedes mitotic exit (characterized by mitotic kinase inactivation via cyclin destruction); this is then followed by cytokinesis. How do cells impose this strict order? Recent findings in budding yeast have suggested a mechanism whereby partitioning of chromosomes into the daughter cell is a prerequisite for the activation of mitotic exit network (MEN). So far, however, a regulatory scheme that would temporally link the initiation of cytokinesis to the execution of mitotic exit has not been determined. We propose that the requirement of MEN components for cytokinesis, their translocation to the mother-daughter neck and triggering of this translocation by inactivation of the mitotic kinase may be the three crucial elements that render initiation of cytokinesis dependent on mitotic exit.
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Affiliation(s)
- Foong May Yeong
- Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609. [corrected]
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50
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Abstract
Cytokinesis is the final event of the cell division cycle, and its completion results in irreversible partition of a mother cell into two daughter cells. Cytokinesis was one of the first cell cycle events observed by simple cell biological techniques; however, molecular characterization of cytokinesis has been slowed by its particular resistance to in vitro biochemical approaches. In recent years, the use of genetic model organisms has greatly advanced our molecular understanding of cytokinesis. While the outcome of cytokinesis is conserved in all dividing organisms, the mechanism of division varies across the major eukaryotic kingdoms. Yeasts and animals, for instance, use a contractile ring that ingresses to the cell middle in order to divide, while plant cells build new cell wall outward to the cortex. As would be expected, there is considerable conservation of molecules involved in cytokinesis between yeast and animal cells, while at first glance, plant cells seem quite different. However, in recent years, it has become clear that some aspects of division are conserved between plant, yeast, and animal cells. In this review we discuss the major recent advances in defining cytokinesis, focusing on deciding where to divide, building the division apparatus, and dividing. In addition, we discuss the complex problem of coordinating the division cycle with the nuclear cycle, which has recently become an area of intense research. In conclusion, we discuss how certain cells have utilized cytokinesis to direct development.
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Affiliation(s)
- David A Guertin
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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