1
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DeMarco AG, Dibble MG, Hall MC. Inducible degradation-coupled phosphoproteomics identifies PP2A Rts1 as a novel eisosome regulator. Front Cell Dev Biol 2024; 12:1451027. [PMID: 39234563 PMCID: PMC11371571 DOI: 10.3389/fcell.2024.1451027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Accepted: 08/02/2024] [Indexed: 09/06/2024] Open
Abstract
Introduction Reversible protein phosphorylation is an abundant post-translational modification dynamically regulated by opposing kinases and phosphatases. Protein phosphorylation has been extensively studied in cell division, where waves of cyclin-dependent kinase activity, peaking in mitosis, drive the sequential stages of the cell cycle. Here we developed and employed a strategy to specifically probe kinase or phosphatase substrates at desired times or experimental conditions in the model organism Saccharomyces cerevisiae. Methods We combined auxin-inducible degradation (AID) with mass spectrometry-based phosphoproteomics, which allowed us to arrest physiologically normal cultures in mitosis prior to rapid phosphatase degradation and phosphoproteome analysis. Results and discussion Our results revealed that protein phosphatase 2A coupled with its B56 regulatory subunit, Rts1 (PP2ARts1), is involved in dephosphorylation of numerous proteins in mitosis, highlighting the need for phosphatases to selectively maintain certain proteins in a hypophosphorylated state in the face of high mitotic kinase activity. Unexpectedly, we observed elevated phosphorylation at many sites on several subunits of the fungal eisosome complex following rapid Rts1 degradation. Eisosomes are dynamic polymeric assemblies that create furrows in the plasma membrane important in regulating nutrient import, lipid metabolism, and stress responses, among other things. We found that PP2ARts1-mediated dephosphorylation of eisosomes promotes their plasma membrane association and we provide evidence that this regulation impacts eisosome roles in metabolic homeostasis. The combination of rapid, inducible protein degradation with proteomic profiling offers several advantages over common protein disruption methods for characterizing substrates of regulatory enzymes involved in dynamic biological processes.
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Affiliation(s)
- Andrew G DeMarco
- Department of Biochemistry, Purdue University, West Lafayette, IN, United States
| | - Marcella G Dibble
- Department of Biochemistry, Purdue University, West Lafayette, IN, United States
| | - Mark C Hall
- Department of Biochemistry, Purdue University, West Lafayette, IN, United States
- Institute for Cancer Research, Purdue University, West Lafayette, IN, United States
- Institute for Drug Discovery, Purdue University, West Lafayette, IN, United States
- Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, United States
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2
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Brambila A, Prichard BE, DeWitt JT, Kellogg DR. Evidence for novel mechanisms that control cell-cycle entry and cell size. Mol Biol Cell 2024; 35:ar46. [PMID: 38231863 PMCID: PMC11064657 DOI: 10.1091/mbc.e23-05-0174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 01/08/2024] [Accepted: 01/10/2024] [Indexed: 01/19/2024] Open
Abstract
Entry into the cell cycle in late G1 phase occurs only when sufficient growth has occurred. In budding yeast, a cyclin called Cln3 is thought to link cell-cycle entry to cell growth. Cln3 accumulates during growth in early G1 phase and eventually helps trigger expression of late G1 phase cyclins that drive cell-cycle entry. All current models for cell-cycle entry assume that expression of late G1 phase cyclins is initiated at the transcriptional level. Current models also assume that the sole function of Cln3 in cell-cycle entry is to promote transcription of late G1 phase cyclins, and that Cln3 works solely in G1 phase. Here, we show that cell cycle-dependent expression of the late G1 phase cyclin Cln2 does not require any functions of the CLN2 promoter. Moreover, Cln3 can influence accumulation of Cln2 protein via posttranscriptional mechanisms. Finally, we show that Cln3 has functions in mitosis that strongly influence cell size. Together, these discoveries reveal the existence of surprising new mechanisms that challenge current models for control of cell-cycle entry and cell size.
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Affiliation(s)
- Amanda Brambila
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064
| | - Beth E. Prichard
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064
| | - Jerry T. DeWitt
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064
| | - Douglas R. Kellogg
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064
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Foltman M, Sanchez-Diaz A. TOR Complex 1: Orchestrating Nutrient Signaling and Cell Cycle Progression. Int J Mol Sci 2023; 24:15745. [PMID: 37958727 PMCID: PMC10647266 DOI: 10.3390/ijms242115745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/26/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023] Open
Abstract
The highly conserved TOR signaling pathway is crucial for coordinating cellular growth with the cell cycle machinery in eukaryotes. One of the two TOR complexes in budding yeast, TORC1, integrates environmental cues and promotes cell growth. While cells grow, they need to copy their chromosomes, segregate them in mitosis, divide all their components during cytokinesis, and finally physically separate mother and daughter cells to start a new cell cycle apart from each other. To maintain cell size homeostasis and chromosome stability, it is crucial that mechanisms that control growth are connected and coordinated with the cell cycle. Successive periods of high and low TORC1 activity would participate in the adequate cell cycle progression. Here, we review the known molecular mechanisms through which TORC1 regulates the cell cycle in the budding yeast Saccharomyces cerevisiae that have been extensively used as a model organism to understand the role of its mammalian ortholog, mTORC1.
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Affiliation(s)
- Magdalena Foltman
- Mechanisms and Regulation of Cell Division Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, 39011 Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Spain
| | - Alberto Sanchez-Diaz
- Mechanisms and Regulation of Cell Division Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, 39011 Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Spain
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4
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DeMarco AG, Dibble MG, Hall MC. Inducible degradation-coupled phosphoproteomics identifies PP2A Rts1 as a novel eisosome regulator. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.24.563668. [PMID: 37961087 PMCID: PMC10634780 DOI: 10.1101/2023.10.24.563668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Reversible protein phosphorylation is an abundant post-translational modification dynamically regulated by opposing kinases and phosphatases. Protein phosphorylation has been extensively studied in cell division, where waves of cyclin-dependent kinase activity, peaking in mitosis, drive the sequential stages of the cell cycle. Here we developed and employed a strategy to specifically probe kinase or phosphatase substrates at desired times or experimental conditions in the model organism Saccharomyces cerevisiae. We combined auxin-inducible degradation (AID) with mass spectrometry-based phosphoproteomics, which allowed us to arrest physiologically normal cultures in mitosis prior to rapid phosphatase degradation and phosphoproteome analysis. Our results revealed that protein phosphatase 2A coupled with its B56 regulatory subunit, Rts1 (PP2ARts1), is involved in dephosphorylation of numerous proteins in mitosis, highlighting the need for phosphatases to selectively maintain certain proteins in a hypophosphorylated state in the face of high mitotic kinase activity. Unexpectedly, we observed elevated phosphorylation at many sites on several subunits of the fungal eisosome complex following rapid Rts1 degradation. Eisosomes are dynamic polymeric assemblies that create furrows in the plasma membrane important in regulating nutrient import, lipid metabolism, and stress responses, among other things. We found that PP2ARts1-mediated dephosphorylation of eisosomes promotes their plasma membrane association and we provide evidence that this regulation impacts eisosome roles in metabolic homeostasis. The combination of rapid, inducible protein degradation with proteomic profiling offers several advantages over common protein disruption methods for characterizing substrates of regulatory enzymes involved in dynamic biological processes.
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Affiliation(s)
- Andrew G. DeMarco
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907
| | - Marcella G. Dibble
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907
| | - Mark C. Hall
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907
- Institute for Cancer Research, Purdue University, West Lafayette, IN, 47907
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5
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DeWitt JT, Chinwuba JC, Kellogg DR. Hyperactive Ras disrupts cell size control and a key step in cell cycle entry in budding yeast. Genetics 2023; 225:iyad144. [PMID: 37531631 PMCID: PMC10758756 DOI: 10.1093/genetics/iyad144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 06/08/2023] [Accepted: 07/15/2023] [Indexed: 08/04/2023] Open
Abstract
Severe defects in cell size are a nearly universal feature of cancer cells. However, the underlying causes are unknown. A previous study suggested that a hyperactive mutant of yeast Ras (ras2G19V) that is analogous to the human Ras oncogene causes cell size defects, which could provide clues to how oncogenes influence cell size. However, the mechanisms by which ras2G19V influences cell size are unknown. Here, we found that ras2G19V inhibits a critical step in cell cycle entry, in which an early G1 phase cyclin induces transcription of late G1 phase cyclins. Thus, ras2G19V drives overexpression of the early G1 phase cyclin Cln3, yet Cln3 fails to induce normal transcription of late G1 phase cyclins, leading to delayed cell cycle entry and increased cell size. ras2G19V influences transcription of late G1 phase cyclins via a poorly understood step in which Cln3 inactivates the Whi5 transcriptional repressor. Previous studies found that yeast Ras relays signals via protein kinase A (PKA); however, ras2G19V appears to influence late G1 phase cyclin expression via novel PKA-independent signaling mechanisms. Together, the data define new mechanisms by which hyperactive Ras influences cell cycle entry and cell size in yeast. Hyperactive Ras also influences expression of G1 phase cyclins in mammalian cells, but the mechanisms remain unclear. Further analysis of Ras signaling in yeast could lead to discovery of new mechanisms by which Ras family members control expression of G1 phase cyclins.
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Affiliation(s)
- Jerry T DeWitt
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064, USA
| | - Jennifer C Chinwuba
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064, USA
| | - Douglas R Kellogg
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064, USA
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6
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Zhang W, Wang S, Jiang B, Guo M. MoRts1, a regulatory subunit of PP2A, is required for fungal development and pathogenicity of Magnaporthe oryzae. Microbiol Res 2023; 269:127313. [PMID: 36696866 DOI: 10.1016/j.micres.2023.127313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 01/18/2023] [Accepted: 01/18/2023] [Indexed: 01/22/2023]
Abstract
Protein phosphatase 2 A (PP2A) is a major heterotrimeric serine/threonine protein phosphatase comprised of three subunits, including structural subunits (A), regulatory subunits (B), and catalytic subunits (C). PP2A has been widely shown to involve in a series of cell signal transduction processes such as cell metabolism, cell cycle regulation, DNA replication, gene transcription and protein translation in yeast and mammalian. However, the roles of PP2A in pathogenic fungi Magnaporthe oryzae still remain unclear. We here found that MoRts1, a gene encoding B regulatory subunit of PP2A homologous to Saccharomyces cerevisiae Rts1, showed up-regulated transcription during conidia and initially infectious stage. Subcellular localization revealed that MoRts1-eGFP was localized to the cytoplasm and septum. Targeted disruption of MoRts1 leads to a reduction of mycelial growth and sporulation, as well as the defects of hydrophobicity, melanin pigmentation and cell wall integrity (CWI). The MoRts1 mutants were less pathogenic to the host plants, compared to the Ku80 strain, and the transcriptional levels of several pathogenicity-related Rho GTPase genes, including MoCdc42, MoRho2, MoRho3, MoRho4, MoRhoX and MoRac1, were significantly decreased in the MoRts1 mutants. Besides, two splicing variants of MoRts1 with unique functions of regulating the growth and pathogenicity were identified, and the B56 domain is vital for determining the sporulation and pathogenicity of M. oryzae. Furthermore, MoRts1 was identified to interact with PP2A catalytic subunit MoPPG1 in vivo in M. oryzae. In summary, our results showed that MoRts1 is an important regulator contributing to the fungal development, and pathogenicity of M. oryzae.
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Affiliation(s)
- Weiwei Zhang
- Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, Hefei 230036, China; College of Plant Protection, Anhui Agricultural University, Hefei 230036, China
| | - Shuaishuai Wang
- Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, Hefei 230036, China; College of Plant Protection, Anhui Agricultural University, Hefei 230036, China
| | - Bingxin Jiang
- Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, Hefei 230036, China; College of Plant Protection, Anhui Agricultural University, Hefei 230036, China
| | - Min Guo
- Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, Hefei 230036, China; College of Plant Protection, Anhui Agricultural University, Hefei 230036, China.
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7
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Yan J, Zhuang L, Wang Y, Jiang Y, Tu Z, Dong C, Chen Y, Zhu Y. Inhibitors of cell cycle checkpoint target Wee1 kinase - a patent review (2003-2022). Expert Opin Ther Pat 2022; 32:1217-1244. [PMID: 36620912 DOI: 10.1080/13543776.2022.2166827] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
INTRODUCTION DNA damage repair in most malignancies with mutation of p53 is more dependent on the G2/M checkpoint. Wee1 kinase is a key regulator of the G2/M checkpoint. If Wee1 is inhibited, it results in cells with unrepaired DNA damage entering mitosis prematurely, leading to mitotic catastrophe and subsequent cell death via the apoptotic program. Therefore, inhibition of Wee1 kinase which overexpressed in several cancer cell lines has emerged as a promising therapy for cancer treatment. AREAS COVERED This review summarizes for the first time the structures of small-molecule inhibitors of Wee1 reported in patents published from 2003 to 2022 and the recent clinical developments. It also provides perspectives on the challenges and the future directions. We used different methods to search different databases (PubMed, Reaxys, clinicaltrials.gov)for the literature we needed. EXPERT OPINION Although the small-molecule inhibitors of Wee1, Adavosertib, and ZN-C3 have entered the clinical phase II, the clinical toxicity exhibited by Adavosertib remains the subject of greater concern. The use of Wee1 inhibitors as monotherapy or in combination therapy remains the main trend in Wee1 inhibitors at present.
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Affiliation(s)
- Jingxue Yan
- School of Science, China Pharmaceutical University, Nanjing, P.R. China
| | - Lili Zhuang
- School of Science, China Pharmaceutical University, Nanjing, P.R. China
| | - Yong Wang
- School of Science, China Pharmaceutical University, Nanjing, P.R. China
| | - Yiqing Jiang
- School of Science, China Pharmaceutical University, Nanjing, P.R. China
| | - Zhenlin Tu
- School of Science, China Pharmaceutical University, Nanjing, P.R. China
| | - Chao Dong
- School of Science, China Pharmaceutical University, Nanjing, P.R. China
| | - Yadong Chen
- School of Science, China Pharmaceutical University, Nanjing, P.R. China
| | - Yong Zhu
- School of Science, China Pharmaceutical University, Nanjing, P.R. China
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8
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Hollenstein DM, Veis J, Romanov N, Gérecová G, Ogris E, Hartl M, Ammerer G, Reiter W. PP2A Rts1 antagonizes Rck2-mediated hyperosmotic stress signaling in yeast. Microbiol Res 2022; 260:127031. [PMID: 35461031 DOI: 10.1016/j.micres.2022.127031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 04/03/2022] [Accepted: 04/05/2022] [Indexed: 11/21/2022]
Abstract
In Saccharomyces cerevisiae, impairment of protein phosphatase PP2ARts1 leads to temperature and hyperosmotic stress sensitivity, yet the underlying mechanism and the scope of action of the phosphatase in the stress response remain elusive. Using a quantitative mass spectrometry-based approach we have identified a set of putative substrate proteins that show both hyperosmotic stress- and PP2ARts1-dependent changes in their phosphorylation pattern. A comparative analysis with published MS-shotgun data revealed that the phosphorylation status of many of these sites is regulated by the MAPKAP kinase Rck2, suggesting that the phosphatase antagonizes Rck2 signaling. Detailed gel mobility shift assays and protein-protein interaction analysis strongly indicate that Rck2 activity is directly regulated by PP2ARts1 via a SLiM B56-family interaction motif, revealing how PP2ARts1 influences the response to hyperosmotic stress in Yeast.
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Affiliation(s)
- D M Hollenstein
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - J Veis
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria; Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - N Romanov
- Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany
| | - G Gérecová
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - E Ogris
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - M Hartl
- Mass Spectrometry Facility, Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - G Ammerer
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - W Reiter
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria; Mass Spectrometry Facility, Max Perutz Labs, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria.
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9
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Pérez AP, Artés MH, Moreno DF, Clotet J, Aldea M. Mad3 modulates the G 1 Cdk and acts as a timer in the Start network. SCIENCE ADVANCES 2022; 8:eabm4086. [PMID: 35522754 PMCID: PMC9075807 DOI: 10.1126/sciadv.abm4086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 03/23/2022] [Indexed: 06/14/2023]
Abstract
Cells maintain their size within limits over successive generations to maximize fitness and survival. Sizer, timer, and adder behaviors have been proposed as possible alternatives to coordinate growth and cell cycle progression. Regarding budding yeast cells, a sizer mechanism is thought to rule cell cycle entry at Start. However, while many proteins controlling the size of these cells have been identified, the mechanistic framework in which they participate to achieve cell size homeostasis is not understood. We show here that intertwined APC and SCF degradation machineries with specific adaptor proteins drive cyclic accumulation of the G1 Cdk in the nucleus, reaching maximal levels at Start. The mechanism incorporates Mad3, a centromeric-signaling protein that subordinates G1 progression to the previous mitosis as a memory factor. This alternating-degradation device displays the properties of a timer and, together with the sizer device, would constitute a key determinant of cell cycle entry.
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Affiliation(s)
- Alexis P. Pérez
- Molecular Biology Institute of Barcelona (IBMB), CSIC, 08028 Barcelona, Catalonia, Spain
- Department of Basic Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Spain
| | - Marta H. Artés
- Molecular Biology Institute of Barcelona (IBMB), CSIC, 08028 Barcelona, Catalonia, Spain
| | - David F. Moreno
- Molecular Biology Institute of Barcelona (IBMB), CSIC, 08028 Barcelona, Catalonia, Spain
| | - Josep Clotet
- Department of Basic Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Spain
| | - Martí Aldea
- Molecular Biology Institute of Barcelona (IBMB), CSIC, 08028 Barcelona, Catalonia, Spain
- Department of Basic Sciences, Universitat Internacional de Catalunya, 08195 Sant Cugat del Vallès, Spain
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10
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Litsios A, Goswami P, Terpstra HM, Coffin C, Vuillemenot LA, Rovetta M, Ghazal G, Guerra P, Buczak K, Schmidt A, Tollis S, Tyers M, Royer CA, Milias-Argeitis A, Heinemann M. The timing of Start is determined primarily by increased synthesis of the Cln3 activator rather than dilution of the Whi5 inhibitor. Mol Biol Cell 2022; 33:rp2. [PMID: 35482514 PMCID: PMC9282015 DOI: 10.1091/mbc.e21-07-0349] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Athanasios Litsios
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, Netherlands
| | - Pooja Goswami
- Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Hanna M Terpstra
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, Netherlands
| | - Carleton Coffin
- Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Luc-Alban Vuillemenot
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, Netherlands
| | - Mattia Rovetta
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, Netherlands
| | - Ghada Ghazal
- Institute for Research in Immunology and Cancer, University of Montréal, Montréal, H3T 1J4 QC, Canada
| | - Paolo Guerra
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, Netherlands
| | - Katarzyna Buczak
- Proteomics Core Facility, Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Alexander Schmidt
- Proteomics Core Facility, Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Sylvain Tollis
- Institute for Research in Immunology and Cancer, University of Montréal, Montréal, H3T 1J4 QC, Canada.,Institute of Biomedicine, University of Eastern Finland, FI-70210 Kuopio, Finland
| | - Mike Tyers
- Institute for Research in Immunology and Cancer, University of Montréal, Montréal, H3T 1J4 QC, Canada
| | - Catherine A Royer
- Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Andreas Milias-Argeitis
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, Netherlands
| | - Matthias Heinemann
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, Netherlands
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11
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Schmoller KM, Lanz MC, Kim J, Koivomagi M, Qu Y, Tang C, Kukhtevich IV, Schneider R, Rudolf F, Moreno DF, Aldea M, Lucena R, Skotheim JM. Whi5 is diluted and protein synthesis does not dramatically increase in pre- Start G1. Mol Biol Cell 2022; 33:lt1. [PMID: 35482510 PMCID: PMC9282012 DOI: 10.1091/mbc.e21-01-0029] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Kurt M Schmoller
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Germany
| | - Michael C Lanz
- Department of Biology, Stanford University, Stanford CA 94305
| | - Jacob Kim
- Department of Biology, Stanford University, Stanford CA 94305
| | - Mardo Koivomagi
- Department of Biology, Stanford University, Stanford CA 94305
| | - Yimiao Qu
- Center for Quantitative Biology and Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Chao Tang
- Center for Quantitative Biology and Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Igor V Kukhtevich
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Germany
| | - Robert Schneider
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Germany
| | - Fabian Rudolf
- D-BSSE, ETH Zurich and Swiss Institute of Bioinformatics, Zurich, Switzerland
| | - David F Moreno
- Molecular Biology Institute of Barcelona, CSIC, Catalonia, Spain
| | - Martí Aldea
- Molecular Biology Institute of Barcelona, CSIC, Catalonia, Spain
| | - Rafael Lucena
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford CA 94305
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12
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Sommer RA, DeWitt JT, Tan R, Kellogg DR. Growth-dependent signals drive an increase in early G1 cyclin concentration to link cell cycle entry with cell growth. eLife 2021; 10:64364. [PMID: 34713806 PMCID: PMC8592568 DOI: 10.7554/elife.64364] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 10/29/2021] [Indexed: 01/13/2023] Open
Abstract
Entry into the cell cycle occurs only when sufficient growth has occurred. In budding yeast, the cyclin Cln3 is thought to initiate cell cycle entry by inactivating a transcriptional repressor called Whi5. Growth-dependent changes in the concentrations of Cln3 or Whi5 have been proposed to link cell cycle entry to cell growth. However, there are conflicting reports regarding the behavior and roles of Cln3 and Whi5. Here, we found no evidence that changes in the concentration of Whi5 play a major role in controlling cell cycle entry. Rather, the data suggest that cell growth triggers cell cycle entry by driving an increase in the concentration of Cln3. We further found that accumulation of Cln3 is dependent upon homologs of mammalian SGK kinases that control cell growth and size. Together, the data are consistent with models in which Cln3 is a crucial link between cell growth and the cell cycle.
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Affiliation(s)
- Robert A Sommer
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, United States
| | - Jerry T DeWitt
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, United States
| | - Raymond Tan
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, United States
| | - Douglas R Kellogg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, United States
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13
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Su XB, Wang M, Schaffner C, Nerusheva OO, Clift D, Spanos C, Kelly DA, Tatham M, Wallek A, Wu Y, Rappsilber J, Jeyaprakash AA, Storchova Z, Hay RT, Marston AL. SUMOylation stabilizes sister kinetochore biorientation to allow timely anaphase. J Cell Biol 2021; 220:e202005130. [PMID: 33929514 PMCID: PMC8094117 DOI: 10.1083/jcb.202005130] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 02/18/2021] [Accepted: 03/24/2021] [Indexed: 12/12/2022] Open
Abstract
During mitosis, sister chromatids attach to microtubules from opposite poles, called biorientation. Sister chromatid cohesion resists microtubule forces, generating tension, which provides the signal that biorientation has occurred. How tension silences the surveillance pathways that prevent cell cycle progression and correct erroneous kinetochore-microtubule attachments remains unclear. Here we show that SUMOylation dampens error correction to allow stable sister kinetochore biorientation and timely anaphase onset. The Siz1/Siz2 SUMO ligases modify the pericentromere-localized shugoshin (Sgo1) protein before its tension-dependent release from chromatin. Sgo1 SUMOylation reduces its binding to protein phosphatase 2A (PP2A), and weakening of this interaction is important for stable biorientation. Unstable biorientation in SUMO-deficient cells is associated with persistence of the chromosome passenger complex (CPC) at centromeres, and SUMOylation of CPC subunit Bir1 also contributes to timely anaphase onset. We propose that SUMOylation acts in a combinatorial manner to facilitate dismantling of the error correction machinery within pericentromeres and thereby sharpen the metaphase-anaphase transition.
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Affiliation(s)
- Xue Bessie Su
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Menglu Wang
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Claudia Schaffner
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Olga O. Nerusheva
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Dean Clift
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, UK
| | - Christos Spanos
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - David A. Kelly
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Michael Tatham
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, UK
| | - Andreas Wallek
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Yehui Wu
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
- Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - A. Arockia Jeyaprakash
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Zuzana Storchova
- Max Planck Institute of Biochemistry, Martinsried, Germany
- Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Ronald T. Hay
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, UK
| | - Adèle L. Marston
- Wellcome Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
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14
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Ash1 and Tup1 dependent repression of the Saccharomyces cerevisiae HO promoter requires activator-dependent nucleosome eviction. PLoS Genet 2020; 16:e1009133. [PMID: 33382702 PMCID: PMC7806131 DOI: 10.1371/journal.pgen.1009133] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 01/13/2021] [Accepted: 11/25/2020] [Indexed: 11/30/2022] Open
Abstract
Transcriptional regulation of the Saccharomyces cerevisiae HO gene is highly complex, requiring a balance of multiple activating and repressing factors to ensure that only a few transcripts are produced in mother cells within a narrow window of the cell cycle. Here, we show that the Ash1 repressor associates with two DNA sequences that are usually concealed within nucleosomes in the HO promoter and recruits the Tup1 corepressor and the Rpd3 histone deacetylase, both of which are required for full repression in daughters. Genome-wide ChIP identified greater than 200 additional sites of co-localization of these factors, primarily within large, intergenic regions from which they could regulate adjacent genes. Most Ash1 binding sites are in nucleosome depleted regions (NDRs), while a small number overlap nucleosomes, similar to HO. We demonstrate that Ash1 binding to the HO promoter does not occur in the absence of the Swi5 transcription factor, which recruits coactivators that evict nucleosomes, including the nucleosomes obscuring the Ash1 binding sites. In the absence of Swi5, artificial nucleosome depletion allowed Ash1 to bind, demonstrating that nucleosomes are inhibitory to Ash1 binding. The location of binding sites within nucleosomes may therefore be a mechanism for limiting repressive activity to periods of nucleosome eviction that are otherwise associated with activation of the promoter. Our results illustrate that activation and repression can be intricately connected, and events set in motion by an activator may also ensure the appropriate level of repression and reset the promoter for the next activation cycle. Nucleosomes inhibit both gene expression and DNA-binding by regulatory factors. Here we examine the role of nucleosomes in regulating the binding of repressive transcription factors to the complex promoter for the yeast HO gene. Ash1 is a sequence-specific DNA-binding protein, and we show that it recruits the Tup1 global repressive factor to the HO promoter. Using a method to determine where Ash1 and Tup1 are bound to DNA throughout the genome, we discovered that Tup1 is also present at most places where Ash1 binds. The majority of these sites are in “Nucleosome Depleted Regions,” or NDRs, where the absence of chromatin makes factor binding easier. We discovered that the HO promoter is an exception, in that the two places where Ash1 binds overlap nucleosomes. Activation of the HO promoter is a complex, multi-step process, and we demonstrated that chromatin factors transiently evict these nucleosomes from the HO promoter during the cell cycle, allowing Ash1 to bind and recruit Tup1. Thus, activators must evict nucleosomes from the promoter to allow the repressive machinery to bind.
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15
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Touati SA, Hofbauer L, Jones AW, Snijders AP, Kelly G, Uhlmann F. Cdc14 and PP2A Phosphatases Cooperate to Shape Phosphoproteome Dynamics during Mitotic Exit. Cell Rep 2020; 29:2105-2119.e4. [PMID: 31722221 PMCID: PMC6857435 DOI: 10.1016/j.celrep.2019.10.041] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 09/27/2019] [Accepted: 10/10/2019] [Indexed: 12/22/2022] Open
Abstract
Temporal control over protein phosphorylation and dephosphorylation is crucial for accurate chromosome segregation and for completion of the cell division cycle during exit from mitosis. In budding yeast, the Cdc14 phosphatase is thought to be a major regulator at this time, while in higher eukaryotes PP2A phosphatases take a dominant role. Here, we use time-resolved phosphoproteome analysis in budding yeast to evaluate the respective contributions of Cdc14, PP2ACdc55, and PP2ARts1. This reveals an overlapping requirement for all three phosphatases during mitotic progression. Our time-resolved phosphoproteome resource reveals how Cdc14 instructs the sequential pattern of phosphorylation changes, in part through preferential recognition of serine-based cyclin-dependent kinase (Cdk) substrates. PP2ACdc55 and PP2ARts1 in turn exhibit a broad substrate spectrum with some selectivity for phosphothreonines and a role for PP2ARts1 in sustaining Aurora kinase activity. These results illustrate synergy and coordination between phosphatases as they orchestrate phosphoproteome dynamics during mitotic progression. Cdc14, PP2ACdc55, and PP2ARts1 phosphatases cooperate during budding yeast mitosis Cdc14 targets serine Cdk motifs for rapid dephosphorylation PP2ACdc55 dephosphorylates Cdk and Plk substrates on threonine residues PP2ARts1 displays regulatory crosstalk with Aurora kinase
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Affiliation(s)
- Sandra A Touati
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
| | - Lorena Hofbauer
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Andrew W Jones
- Mass Spectrometry Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Ambrosius P Snijders
- Mass Spectrometry Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Gavin Kelly
- Bioinformatics & Biostatistics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
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16
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Gu Y, Oliferenko S. The principles of cellular geometry scaling. Curr Opin Cell Biol 2020; 68:20-27. [PMID: 32950004 DOI: 10.1016/j.ceb.2020.08.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 01/11/2023]
Abstract
Cellular dimensions profoundly influence cellular physiology. For unicellular organisms, this has direct bearing on their ecology and evolution. The morphology of a cell is governed by scaling rules. As it grows, the ratio of its surface area to volume is expected to decrease. Similarly, if environmental conditions force proliferating cells to settle on different size optima, cells of the same type may exhibit size-dependent variation in cellular processes. In fungi, algae and plants where cells are surrounded by a rigid wall, division at smaller size often produces immediate changes in geometry, decreasing cell fitness. Here, we discuss how cells interpret their size, buffer against changes in shape and, if necessary, scale their polarity to maintain optimal shape at different cell volumes.
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Affiliation(s)
- Ying Gu
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK; Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, SE1 1UL, UK
| | - Snezhana Oliferenko
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK; Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, SE1 1UL, UK.
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17
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Yahya G, Wu Y, Peplowska K, Röhrl J, Soh YM, Bürmann F, Gruber S, Storchova Z. Phospho-regulation of the Shugoshin - Condensin interaction at the centromere in budding yeast. PLoS Genet 2020; 16:e1008569. [PMID: 32810145 PMCID: PMC7454948 DOI: 10.1371/journal.pgen.1008569] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 08/28/2020] [Accepted: 05/22/2020] [Indexed: 01/07/2023] Open
Abstract
Correct bioriented attachment of sister chromatids to the mitotic spindle is essential for chromosome segregation. In budding yeast, the conserved protein shugoshin (Sgo1) contributes to biorientation by recruiting the protein phosphatase PP2A-Rts1 and the condensin complex to centromeres. Using peptide prints, we identified a Serine-Rich Motif (SRM) of Sgo1 that mediates the interaction with condensin and is essential for centromeric condensin recruitment and the establishment of biorientation. We show that the interaction is regulated via phosphorylation within the SRM and we determined the phospho-sites using mass spectrometry. Analysis of the phosphomimic and phosphoresistant mutants revealed that SRM phosphorylation disrupts the shugoshin–condensin interaction. We present evidence that Mps1, a central kinase in the spindle assembly checkpoint, directly phosphorylates Sgo1 within the SRM to regulate the interaction with condensin and thereby condensin localization to centromeres. Our findings identify novel mechanisms that control shugoshin activity at the centromere in budding yeast. Proper chromosome segregation in eukaryotes is ensured through correct attachment of the spindle microtubules to the centromeric chromosomal regions. The attachment is mediated via the multimolecular proteinaceous complex called the kinetochore. This enables the establishment of bioirentation, when each sister chromatid is attached to microtubules emanating from opposite spindle poles. Shugoshin (Sgo1) is a conserved centromeric protein that facilitates biorientation through its interactions with the protein phosphatase PP2A-Rts1, chromosome passenger complex and centromeric condensin. Here, we identified a serine-rich motif that is required for the interaction of shugoshin with the condensin complex. We show that loss of this region impairs condensin enrichment at the centromere, chromosome biorientation, segregation as well as the function of the chromosome passenger complex in the error correction. Moreover, the interaction is phosphoregulated, as phosphorylation of the serine-rich motif on Sgo1 disrupts its interaction with condensin. Finally, we show that the conserved spindle assembly checkpoint kinase Mps1 is responsible for this phosphorylation. Our findings uncover novel regulatory mechanisms that facilitate proper chromosome segregation.
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Affiliation(s)
- Galal Yahya
- Department of Microbiology and Immunology, School of Pharmacy, Zagazig University, Egypt
- Department of Molecular Genetics, TU Kaiserlautern, Kaiserslautern, Germany
| | - Yehui Wu
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Karolina Peplowska
- Max Planck Institute of Biochemistry, Martinsried, Germany
- Genomics and Bioinformatics Shared Resource, University of Hawaii Cancer Center, Honolulu, United States of America
| | - Jennifer Röhrl
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Young-Min Soh
- Department of Fundamental Microbiology, UNIL-Sorge District, Lausanne, Switzerland
| | - Frank Bürmann
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
| | - Stephan Gruber
- Department of Fundamental Microbiology, UNIL-Sorge District, Lausanne, Switzerland
| | - Zuzana Storchova
- Department of Molecular Genetics, TU Kaiserlautern, Kaiserslautern, Germany
- * E-mail:
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18
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Alcaide-Gavilán M, Lucena R, Banuelos S, Kellogg DR. Conserved Ark1-related kinases function in a TORC2 signaling network. Mol Biol Cell 2020; 31:2057-2069. [PMID: 32614710 PMCID: PMC7543068 DOI: 10.1091/mbc.e19-12-0685] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In all orders of life, cell cycle progression in proliferating cells is dependent on cell growth, and the extent of growth required for cell cycle progression is proportional to growth rate. Thus, cells growing rapidly in rich nutrients are substantially larger than slow-growing cells. In budding yeast, a conserved signaling network surrounding Tor complex 2 (target of rapamycin complex 2; TORC2) controls growth rate and cell size in response to nutrient availability. Here, a search for new components of the TORC2 network identified a pair of redundant kinase paralogues called Ark1 and Prk1. Previous studies found that Ark/Prk play roles in endocytosis. Here, we show that Ark/Prk are embedded in the TORC2 network, where they appear to influence TORC2 signaling independently of their roles in endocytosis. We also show that reduced endocytosis leads to increased cell size, which suggests that cell size homeostasis requires coordinated control of plasma membrane growth and endocytosis. The discovery that Ark/Prk are embedded in the TORC2 network suggests a model in which TORC2-dependent signals control both plasma membrane growth and endocytosis, which would ensure that the rates of each process are matched to each other and to the availability of nutrients so that cells achieve and maintain an appropriate size.
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Affiliation(s)
- Maria Alcaide-Gavilán
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Rafael Lucena
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Selene Banuelos
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Douglas R Kellogg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
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19
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Petty EL, Pillus L. Cell cycle roles for GCN5 revealed through genetic suppression. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1864:194625. [PMID: 32798737 DOI: 10.1016/j.bbagrm.2020.194625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 08/11/2020] [Accepted: 08/11/2020] [Indexed: 11/17/2022]
Abstract
The conserved acetyltransferase Gcn5 is a member of several complexes in eukaryotic cells, playing roles in regulating chromatin organization, gene expression, metabolism, and cell growth and differentiation via acetylation of both nuclear and cytoplasmic proteins. Distinct functions of Gcn5 have been revealed through a combination of biochemical and genetic approaches in many in vitro studies and model organisms. In this review, we focus on the unique insights that have been gleaned from suppressor studies of gcn5 phenotypes in the budding yeast Saccharomyces cerevisiae. Such studies were fundamental in the early understanding of the balance of counteracting chromatin activities in regulating transcription. Most recently, suppressor screens have revealed roles for Gcn5 in early cell cycle (G1 to S) gene expression and regulation of chromosome segregation during mitosis. Much has been learned, but many questions remain which will be informed by focused analysis of additional genetic and physical interactions.
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Affiliation(s)
- Emily L Petty
- University of California, San Diego, Division of Biological Sciences, Section of Molecular Biology, UCSD Moores Cancer Center, United States of America.
| | - Lorraine Pillus
- University of California, San Diego, Division of Biological Sciences, Section of Molecular Biology, UCSD Moores Cancer Center, United States of America.
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20
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Fernández-Del-Río L, Kelly ME, Contreras J, Bradley MC, James AM, Murphy MP, Payne GS, Clarke CF. Genes and lipids that impact uptake and assimilation of exogenous coenzyme Q in Saccharomyces cerevisiae. Free Radic Biol Med 2020; 154:105-118. [PMID: 32387128 PMCID: PMC7611304 DOI: 10.1016/j.freeradbiomed.2020.04.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 04/18/2020] [Accepted: 04/28/2020] [Indexed: 12/13/2022]
Abstract
Coenzyme Q (CoQ) is an essential player in the respiratory electron transport chain and is the only lipid-soluble antioxidant synthesized endogenously in mammalian and yeast cells. In humans, genetic mutations, pathologies, certain medical treatments, and aging, result in CoQ deficiencies, which are linked to mitochondrial, cardiovascular, and neurodegenerative diseases. The only strategy available for these patients is CoQ supplementation. CoQ supplements benefit a small subset of patients, but the poor solubility of CoQ greatly limits treatment efficacy. Consequently, the efficient delivery of CoQ to the mitochondria and restoration of respiratory function remains a major challenge. A better understanding of CoQ uptake and mitochondrial delivery is crucial to make this molecule a more efficient and effective therapeutic tool. In this study, we investigated the mechanism of CoQ uptake and distribution using the yeast Saccharomyces cerevisiae as a model organism. The addition of exogenous CoQ was tested for the ability to restore growth on non-fermentable medium in several strains that lack CoQ synthesis (coq mutants). Surprisingly, we discovered that the presence of CoQ biosynthetic intermediates impairs assimilation of CoQ into a functional respiratory chain in yeast cells. Moreover, a screen of 40 gene deletions considered to be candidates to prevent exogenous CoQ from rescuing growth of the CoQ-less coq2Δ mutant, identified six novel genes (CDC10, RTS1, RVS161, RVS167, VPS1, and NAT3) as necessary for efficient trafficking of CoQ to mitochondria. The proteins encoded by these genes represent essential steps in the pathways responsible for transport of exogenously supplied CoQ to its functional sites in the cell, and definitively associate CoQ distribution with endocytosis and intracellular vesicular trafficking pathways conserved from yeast to human cells.
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Affiliation(s)
- Lucía Fernández-Del-Río
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, USA
| | - Miranda E Kelly
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, USA
| | - Jaime Contreras
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, USA
| | - Michelle C Bradley
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, USA
| | - Andrew M James
- MRC Mitochondrial Biology Unit, University of Cambridge, UK
| | - Michael P Murphy
- MRC Mitochondrial Biology Unit, University of Cambridge, UK; Department of Medicine, University of Cambridge, UK
| | - Gregory S Payne
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, USA
| | - Catherine F Clarke
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, USA.
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21
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Chen Y, Zhao G, Zahumensky J, Honey S, Futcher B. Differential Scaling of Gene Expression with Cell Size May Explain Size Control in Budding Yeast. Mol Cell 2020; 78:359-370.e6. [PMID: 32246903 DOI: 10.1016/j.molcel.2020.03.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 12/14/2019] [Accepted: 03/10/2020] [Indexed: 01/25/2023]
Abstract
Yeast cells must grow to a critical size before committing to division. It is unknown how size is measured. We find that as cells grow, mRNAs for some cell-cycle activators scale faster than size, increasing in concentration, while mRNAs for some inhibitors scale slower than size, decreasing in concentration. Size-scaled gene expression could cause an increasing ratio of activators to inhibitors with size, triggering cell-cycle entry. Consistent with this, expression of the CLN2 activator from the promoter of the WHI5 inhibitor, or vice versa, interfered with cell size homeostasis, yielding a broader distribution of cell sizes. We suggest that size homeostasis comes from differential scaling of gene expression with size. Differential regulation of gene expression as a function of cell size could affect many cellular processes.
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Affiliation(s)
- Yuping Chen
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794-5222, USA
| | - Gang Zhao
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794-5222, USA
| | - Jakub Zahumensky
- Department of Functional Organization of Biomembranes, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, Prague 142 20, Czech Republic
| | - Sangeet Honey
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794-5222, USA
| | - Bruce Futcher
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794-5222, USA.
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22
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Wesley CC, Mishra S, Levy DL. Organelle size scaling over embryonic development. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2020; 9:e376. [PMID: 32003549 DOI: 10.1002/wdev.376] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/19/2019] [Accepted: 01/08/2020] [Indexed: 12/13/2022]
Abstract
Cell division without growth results in progressive cell size reductions during early embryonic development. How do the sizes of intracellular structures and organelles scale with cell size and what are the functional implications of such scaling relationships? Model organisms, in particular Caenorhabditis elegans worms, Drosophila melanogaster flies, Xenopus laevis frogs, and Mus musculus mice, have provided insights into developmental size scaling of the nucleus, mitotic spindle, and chromosomes. Nuclear size is regulated by nucleocytoplasmic transport, nuclear envelope proteins, and the cytoskeleton. Regulators of microtubule dynamics and chromatin compaction modulate spindle and mitotic chromosome size scaling, respectively. Developmental scaling relationships for membrane-bound organelles, like the endoplasmic reticulum, Golgi, mitochondria, and lysosomes, have been less studied, although new imaging approaches promise to rectify this deficiency. While models that invoke limiting components and dynamic regulation of assembly and disassembly can account for some size scaling relationships in early embryos, it will be exciting to investigate the contribution of newer concepts in cell biology such as phase separation and interorganellar contacts. With a growing understanding of the underlying mechanisms of organelle size scaling, future studies promise to uncover the significance of proper scaling for cell function and embryonic development, as well as how aberrant scaling contributes to disease. This article is categorized under: Establishment of Spatial and Temporal Patterns > Regulation of Size, Proportion, and Timing Early Embryonic Development > Fertilization to Gastrulation Comparative Development and Evolution > Model Systems.
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Affiliation(s)
- Chase C Wesley
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming
| | - Sampada Mishra
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming
| | - Daniel L Levy
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming
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23
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Protein Phosphatases in G1 Regulation. Int J Mol Sci 2020; 21:ijms21020395. [PMID: 31936296 PMCID: PMC7013402 DOI: 10.3390/ijms21020395] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/29/2019] [Accepted: 12/31/2019] [Indexed: 01/15/2023] Open
Abstract
Eukaryotic cells make the decision to proliferate, to differentiate or to cease dividing during G1, before passage through the restriction point or Start. Keeping cyclin-dependent kinase (CDK) activity low during this period restricts commitment to a new cell cycle and is essential to provide the adequate timeframe for the sensing of environmental signals. Here, we review the role of protein phosphatases in the modulation of CDK activity and as the counteracting force for CDK-dependent substrate phosphorylation, in budding and fission yeast. Moreover, we discuss recent findings that place protein phosphatases in the interface between nutritional signalling pathways and the cell cycle machinery.
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24
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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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25
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Aouida M, Eshrif A, Ramotar D. Yeast Lacking the PP2A Phosphatase Regulatory Subunit Rts1 Sensitizes rad51 Mutants to Specific DNA Damaging Agents. Front Genet 2019; 10:1117. [PMID: 31781172 PMCID: PMC6857479 DOI: 10.3389/fgene.2019.01117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 10/16/2019] [Indexed: 11/13/2022] Open
Abstract
Rts1 is a regulatory subunit of the trimeric protein phosphatase 2A phosphatase and it participates in many biological processes by modulating the phosphorylation status of proteins. Consistent with its role, mutants lacking Rts1 display multiple phenotypes. We have previously performed a high throughput screen to search for yeast haploid mutants with altered sensitivity to the anticancer drug bleomycin, which acts by damaging the DNA to produce single and double strand breaks. RTS1 was among the genes that when singly deleted cause sensitivity to bleomycin. We investigate whether Rts1 plays a role in the repair of bleomycin-induced DNA lesions. We show that deletion of the RTS1 gene in the rad51 null background, lacking Rad51 known to be involved in the repair of bleomycin-induced DNA lesions, resulted in double mutants that were sensitized to bleomycin and not to other DNA damaging agents that creates DNA adducts. We further show that Rts1 has the ability to bind to DNA and in its absence cells displayed an increase in the frequency of both spontaneous and bleomycin-induced mutations compared to the parent. This is the first report implicating Rts1 with a role in DNA damage and repair, perhaps regulating the phosphorylation status of one or more proteins involved in the repair of DNA strand breaks.
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Affiliation(s)
- Mustapha Aouida
- College of Health and Life Sciences, Hamad Bin Khalifa University, Education City, Qatar Foundation, Doha, Qatar
| | - Abdelmoez Eshrif
- Maisonneuve-Rosemont Hospital, Research Center, Department of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Dindial Ramotar
- College of Health and Life Sciences, Hamad Bin Khalifa University, Education City, Qatar Foundation, Doha, Qatar.,Maisonneuve-Rosemont Hospital, Research Center, Department of Medicine, Université de Montréal, Montréal, QC, Canada
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26
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Litsios A, Huberts DHEW, Terpstra HM, Guerra P, Schmidt A, Buczak K, Papagiannakis A, Rovetta M, Hekelaar J, Hubmann G, Exterkate M, Milias-Argeitis A, Heinemann M. Differential scaling between G1 protein production and cell size dynamics promotes commitment to the cell division cycle in budding yeast. Nat Cell Biol 2019; 21:1382-1392. [PMID: 31685990 DOI: 10.1038/s41556-019-0413-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 09/25/2019] [Indexed: 12/28/2022]
Abstract
In the unicellular eukaryote Saccharomyces cerevisiae, Cln3-cyclin-dependent kinase activity enables Start, the irreversible commitment to the cell division cycle. However, the concentration of Cln3 has been paradoxically considered to remain constant during G1, due to the presumed scaling of its production rate with cell size dynamics. Measuring metabolic and biosynthetic activity during cell cycle progression in single cells, we found that cells exhibit pulses in their protein production rate. Rather than scaling with cell size dynamics, these pulses follow the intrinsic metabolic dynamics, peaking around Start. Using a viral-based bicistronic construct and targeted proteomics to measure Cln3 at the single-cell and population levels, we show that the differential scaling between protein production and cell size leads to a temporal increase in Cln3 concentration, and passage through Start. This differential scaling causes Start in both daughter and mother cells across growth conditions. Thus, uncoupling between two fundamental physiological parameters drives cell cycle commitment.
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Affiliation(s)
- Athanasios Litsios
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Daphne H E W Huberts
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Hanna M Terpstra
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Paolo Guerra
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Alexander Schmidt
- Proteomics Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Katarzyna Buczak
- Proteomics Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Alexandros Papagiannakis
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Mattia Rovetta
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Johan Hekelaar
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Georg Hubmann
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
- Department of Biology, Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Heverlee, Belgium
- Center for Microbiology, VIB, Heverlee, Belgium
| | - Marten Exterkate
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Andreas Milias-Argeitis
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands.
| | - Matthias Heinemann
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands.
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27
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Leitao RM, Jasani A, Talavara RA, Pham A, Okobi QJ, Kellogg DR. A Conserved PP2A Regulatory Subunit Enforces Proportional Relationships Between Cell Size and Growth Rate. Genetics 2019; 213:517-528. [PMID: 31488515 PMCID: PMC6781898 DOI: 10.1534/genetics.119.301012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 08/10/2019] [Indexed: 11/18/2022] Open
Abstract
Cell size is proportional to growth rate. Thus, cells growing rapidly in rich nutrients can be nearly twice the size of cells growing slowly in poor nutrients. This proportional relationship appears to hold across all orders of life, yet the underlying mechanisms are unknown. In budding yeast, most growth occurs during mitosis, and the proportional relationship between cell size and growth rate is therefore enforced primarily by modulating growth in mitosis. When growth is slow, the duration of mitosis is increased to allow more time for growth, yet the amount of growth required to complete mitosis is reduced, which leads to the birth of small daughter cells. Previous studies have found that Rts1, a member of the conserved B56 family of protein phosphatase 2A regulatory subunits, works in a TORC2 signaling network that influences cell size and growth rate. However, it was unclear whether Rts1 influences cell growth and size in mitosis. Here, we show that Rts1 is required for the proportional relationship between cell size and growth rate during mitosis. Moreover, nutrients and Rts1 influence the duration and extent of growth in mitosis via Wee1 and Pds1/securin, two conserved regulators of mitotic progression. Together, the data are consistent with a model in which global signals that set growth rate also set the critical amount of growth required for cell cycle progression, which would provide a simple mechanistic explanation for the proportional relationship between cell size and growth rate.
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Affiliation(s)
- Ricardo M Leitao
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064
| | - Akshi Jasani
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064
| | - Rafael A Talavara
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064
| | - Annie Pham
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064
| | - Quincy J Okobi
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064
| | - Douglas R Kellogg
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064
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28
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Parnell EJ, Stillman DJ. Multiple Negative Regulators Restrict Recruitment of the SWI/SNF Chromatin Remodeler to the HO Promoter in Saccharomyces cerevisiae. Genetics 2019; 212:1181-1204. [PMID: 31167839 PMCID: PMC6707452 DOI: 10.1534/genetics.119.302359] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 05/30/2019] [Indexed: 01/22/2023] Open
Abstract
Activation of the Saccharomyces cerevisiae HO promoter is highly regulated, requiring the ordered recruitment of activators and coactivators and allowing production of only a few transcripts in mother cells within a short cell cycle window. We conducted genetic screens to identify the negative regulators of HO expression necessary to limit HO transcription. Known repressors of HO (Ash1 and Rpd3) were identified, as well as several additional chromatin-associated factors including the Hda1 histone deacetylase, the Isw2 chromatin remodeler, and the corepressor Tup1 We also identified clusters of HO promoter mutations that suggested roles for the Dot6/Tod6 (PAC site) and Ume6 repression pathways. We used ChIP assays with synchronized cells to validate the involvement of these factors and map the association of Ash1, Dot6, and Ume6 with the HO promoter to a brief window in the cell cycle between binding of the initial activating transcription factor and initiation of transcription. We found that Ash1 and Ume6 each recruit the Rpd3 histone deacetylase to HO, and their effects are additive. In contrast, Rpd3 was not recruited significantly to the PAC site, suggesting this site has a distinct mechanism for repression. Increases in HO expression and SWI/SNF recruitment were all additive upon loss of Ash1, Ume6, and PAC site factors, indicating the convergence of independent pathways for repression. Our results demonstrate that multiple protein complexes are important for limiting the spread of SWI/SNF-mediated nucleosome eviction across the HO promoter, suggesting that regulation requires a delicate balance of activities that promote and repress transcription.
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Affiliation(s)
- Emily J Parnell
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah 84112
| | - David J Stillman
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah 84112
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29
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Bállega E, Carballar R, Samper B, Ricco N, Ribeiro MP, Bru S, Jiménez J, Clotet J. Comprehensive and quantitative analysis of G1 cyclins. A tool for studying the cell cycle. PLoS One 2019; 14:e0218531. [PMID: 31237904 PMCID: PMC6592645 DOI: 10.1371/journal.pone.0218531] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 06/04/2019] [Indexed: 12/13/2022] Open
Abstract
In eukaryotes, the cell cycle is driven by the actions of several cyclin dependent kinases (CDKs) and an array of regulatory proteins called cyclins, due to the cyclical expression patterns of the latter. In yeast, the accepted pattern of cyclin waves is based on qualitative studies performed by different laboratories using different strain backgrounds, different growing conditions and media, and different kinds of genetic manipulation. Additionally, only the subset of cyclins regulating Cdc28 was included, while the Pho85 cyclins were excluded. We describe a comprehensive, quantitative and accurate blueprint of G1 cyclins in the yeast Saccharomyces cerevisiae that, in addition to validating previous conclusions, yields new findings and establishes an accurate G1 cyclin blueprint. For the purposes of this research, we produced a collection of strains with all G1 cyclins identically tagged using the same and most respectful procedure possible. We report the contribution of each G1 cyclin for a broad array of growing and stress conditions, describe an unknown role for Pcl2 in heat-stress conditions and demonstrate the importance of maintaining the 3’UTR sequence of cyclins untouched during the tagging process.
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Affiliation(s)
- Elisabet Bállega
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Reyes Carballar
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Bàrbara Samper
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Natalia Ricco
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Mariana P. Ribeiro
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Samuel Bru
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Javier Jiménez
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
- * E-mail: (JJ); (JC)
| | - Josep Clotet
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
- * E-mail: (JJ); (JC)
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30
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Han Q, Pan C, Wang Y, Wang N, Wang Y, Sang J. The PP2A regulatory subunits, Cdc55 and Rts1, play distinct roles in Candida albicans' growth, morphogenesis, and virulence. Fungal Genet Biol 2019; 131:103240. [PMID: 31185286 DOI: 10.1016/j.fgb.2019.103240] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 06/06/2019] [Accepted: 06/06/2019] [Indexed: 11/25/2022]
Abstract
Protein phosphatase-2A (PP2A) is a heterotrimeric enzyme composed of a catalytic subunit, a regulatory subunit, and a structural subunit. In Candida albicans, Cdc55 and Rts1 have been identified as possible regulatory subunits of PP2A containing the catalytic subunit Pph21 and structural subunit Tpd3. The Tpd3-Pph21 phosphatase regulates cell morphogenesis and division. However, the functions of Cdc55 and Rts1 remain unclear. Here, we constructed cdc55Δ/Δ and rts1Δ/Δ mutants and found that they exhibit different defects in multiple phenotypes although both show similar hyperphosphorylation of the septin Sep7 and aberrant septin organization. Under yeast growth conditions, the cdc55Δ/Δ mutant grows slowly as pseudohyphae with some cells lacking the nucleus, while rts1Δ/Δ cells are round and enlarged and seem to undergo incomplete cell separation producing multinucleated cells. Strong chitin deposition occurs at the septum of cdc55Δ/Δ cells and on the surface of rts1Δ/Δ cells, which likely contributes to increased susceptibility to caspofungin. Also, cdc55Δ/Δ exhibits severe defects in hyphal and biofilm formation, while rts1Δ/Δ is partially defective. Both mutants show reduced virulence in mice, suggesting that PP2A-B subunits could serve as potential antifungal targets.
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Affiliation(s)
- Qi Han
- Key Laboratory of Cell Proliferation and Regulation Biology, College of Life Sciences, Beijing Normal University, Beijing, China
| | - Chaoying Pan
- Key Laboratory of Cell Proliferation and Regulation Biology, College of Life Sciences, Beijing Normal University, Beijing, China
| | - Yueqing Wang
- Key Laboratory of Cell Proliferation and Regulation Biology, College of Life Sciences, Beijing Normal University, Beijing, China
| | - Na Wang
- Key Laboratory of Cell Proliferation and Regulation Biology, College of Life Sciences, Beijing Normal University, Beijing, China
| | - Yue Wang
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore; Depatment of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
| | - Jianli Sang
- Key Laboratory of Cell Proliferation and Regulation Biology, College of Life Sciences, Beijing Normal University, Beijing, China.
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31
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Ariño J, Velázquez D, Casamayor A. Ser/Thr protein phosphatases in fungi: structure, regulation and function. MICROBIAL CELL 2019; 6:217-256. [PMID: 31114794 PMCID: PMC6506691 DOI: 10.15698/mic2019.05.677] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Reversible phospho-dephosphorylation of proteins is a major mechanism for the control of cellular functions. By large, Ser and Thr are the most frequently residues phosphorylated in eukar-yotes. Removal of phosphate from these amino acids is catalyzed by a large family of well-conserved enzymes, collectively called Ser/Thr protein phosphatases. The activity of these enzymes has an enormous impact on cellular functioning. In this work we pre-sent the members of this family in S. cerevisiae and other fungal species, and review the most recent findings concerning their regu-lation and the roles they play in the most diverse aspects of cell biology.
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Affiliation(s)
- Joaquín Ariño
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
| | - Diego Velázquez
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
| | - Antonio Casamayor
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
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32
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Baro B, Játiva S, Calabria I, Vinaixa J, Bech-Serra JJ, de LaTorre C, Rodrigues J, Hernáez ML, Gil C, Barceló-Batllori S, Larsen MR, Queralt E. SILAC-based phosphoproteomics reveals new PP2A-Cdc55-regulated processes in budding yeast. Gigascience 2018; 7:4982941. [PMID: 29688323 PMCID: PMC5967524 DOI: 10.1093/gigascience/giy047] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 04/18/2018] [Indexed: 01/12/2023] Open
Abstract
Background Protein phosphatase 2A (PP2A) is a family of conserved serine/threonine phosphatases involved in several essential aspects of cell growth and proliferation. PP2ACdc55 phosphatase has been extensively related to cell cycle events in budding yeast; however, few PP2ACdc55 substrates have been identified. Here, we performed a quantitative mass spectrometry approach to reveal new substrates of PP2ACdc55 phosphatase and new PP2A-related processes in mitotic arrested cells. Results We identified 62 statistically significant PP2ACdc55 substrates involved mainly in actin-cytoskeleton organization. In addition, we validated new PP2ACdc55 substrates such as Slk19 and Lte1, involved in early and late anaphase pathways, and Zeo1, a component of the cell wall integrity pathway. Finally, we constructed docking models of Cdc55 and its substrate Mob1. We found that the predominant interface on Cdc55 is mediated by a protruding loop consisting of residues 84–90, thus highlighting the relevance of these aminoacids for substrate interaction. Conclusions We used phosphoproteomics of Cdc55-deficient cells to uncover new PP2ACdc55 substrates and functions in mitosis. As expected, several hyperphosphorylated proteins corresponded to Cdk1-dependent substrates, although other kinases’ consensus motifs were also enriched in our dataset, suggesting that PP2ACdc55 counteracts and regulates other kinases distinct from Cdk1. Indeed, Pkc1 emerged as a novel node of PP2ACdc55 regulation, highlighting a major role of PP2ACdc55 in actin cytoskeleton and cytokinesis, gene ontology terms significantly enriched in the PP2ACdc55-dependent phosphoproteome.
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Affiliation(s)
- Barbara Baro
- Cell Cycle Group, Cancer Epigenetics and Biology Program, Institut d'Investigacions Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Soraya Játiva
- Cell Cycle Group, Cancer Epigenetics and Biology Program, Institut d'Investigacions Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Inés Calabria
- Cell Cycle Group, Cancer Epigenetics and Biology Program, Institut d'Investigacions Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Judith Vinaixa
- Cell Cycle Group, Cancer Epigenetics and Biology Program, Institut d'Investigacions Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Joan-Josep Bech-Serra
- IDIBELL Proteomics Unit, Institut d'Investigacions Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Carolina de LaTorre
- IDIBELL Proteomics Unit, Institut d'Investigacions Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain
| | - João Rodrigues
- Structural Biology Department, School of Medicine, Stanford, California, USA
| | - María Luisa Hernáez
- Proteomics Unit, Parque Científico de Madrid, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Concha Gil
- Proteomics Unit, Parque Científico de Madrid, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Silvia Barceló-Batllori
- IDIBELL Proteomics Unit, Institut d'Investigacions Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Martin R Larsen
- Department of Biochemistry and Molecular Biology, Odense M, Denmark
| | - Ethel Queralt
- Cell Cycle Group, Cancer Epigenetics and Biology Program, Institut d'Investigacions Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
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33
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Blank HM, Callahan M, Pistikopoulos IPE, Polymenis AO, Polymenis M. Scaling of G1 Duration with Population Doubling Time by a Cyclin in Saccharomyces cerevisiae. Genetics 2018; 210:895-906. [PMID: 30150288 PMCID: PMC6218239 DOI: 10.1534/genetics.118.301507] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/24/2018] [Indexed: 01/09/2023] Open
Abstract
The longer cells stay in particular phases of the cell cycle, the longer it will take these cell populations to increase. However, the above qualitative description has very little predictive value, unless it can be codified mathematically. A quantitative relation that defines the population doubling time (Td) as a function of the time eukaryotic cells spend in specific cell cycle phases would be instrumental for estimating rates of cell proliferation and for evaluating introduced perturbations. Here, we show that in human cells, the length of the G1 phase (TG1) regressed on Td with a slope of ≈0.75, while in the yeast Saccharomyces cerevisiae, the slope was slightly smaller, at ≈0.60. On the other hand, cell size was not strongly associated with Td or TG1 in cell cultures that were proliferating at different rates. Furthermore, we show that levels of the yeast G1 cyclin Cln3p were positively associated with rates of cell proliferation over a broad range, at least in part through translational control mediated by a short upstream ORF (uORF) in the CLN3 transcript. Cln3p was also necessary for the proper scaling between TG1 and Td In contrast, yeast lacking the Whi5p transcriptional repressor maintained the scaling between TG1 and Td These data reveal fundamental scaling relationships between the duration of eukaryotic cell cycle phases and rates of cell proliferation, point to the necessary role of Cln3p in these relationships in yeast, and provide a mechanistic basis linking Cln3p levels to proliferation rates and the scaling of G1 with doubling time.
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Affiliation(s)
- Heidi M Blank
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Michelle Callahan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | | | - Aggeliki O Polymenis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Michael Polymenis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
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34
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Martínez-Láinez JM, Moreno DF, Parisi E, Clotet J, Aldea M. Centromeric signaling proteins boost G1 cyclin degradation and modulate cell size in budding yeast. PLoS Biol 2018; 16:e2005388. [PMID: 30080861 PMCID: PMC6095599 DOI: 10.1371/journal.pbio.2005388] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 08/16/2018] [Accepted: 07/20/2018] [Indexed: 11/18/2022] Open
Abstract
Cell size scales with ploidy in a great range of eukaryotes, but the underlying mechanisms remain unknown. Using various orthogonal single-cell approaches, we show that cell size increases linearly with centromere (CEN) copy number in budding yeast. This effect is due to a G1 delay mediated by increased degradation of Cln3, the most upstream G1 cyclin acting at Start, and specific centromeric signaling proteins, namely Mad3 and Bub3. Mad3 binds both Cln3 and Cdc4, the adaptor component of the Skp1/Cul1/F-box (SCF) complex that targets Cln3 for degradation, these interactions being essential for the CEN-dosage dependent effects on cell size. Our results reveal a pathway that modulates cell size as a function of CEN number, and we speculate that, in cooperation with other CEN-independent mechanisms, it could assist the cell to attain efficient mass/ploidy ratios.
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Affiliation(s)
- Joan M. Martínez-Láinez
- Institut de Biologia Molecular de Barcelona IBMB-CSIC, Barcelona, Catalonia, Spain
- Departament de Ciències Bàsiques, Universitat Internacional de Catalunya, Barcelona, Spain
| | - David F. Moreno
- Institut de Biologia Molecular de Barcelona IBMB-CSIC, Barcelona, Catalonia, Spain
| | - Eva Parisi
- Institut de Biologia Molecular de Barcelona IBMB-CSIC, Barcelona, Catalonia, Spain
| | - Josep Clotet
- Departament de Ciències Bàsiques, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Martí Aldea
- Institut de Biologia Molecular de Barcelona IBMB-CSIC, Barcelona, Catalonia, Spain
- Departament de Ciències Bàsiques, Universitat Internacional de Catalunya, Barcelona, Spain
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35
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Petty EL, Evpak M, Pillus L. Connecting GCN5's centromeric SAGA to the mitotic tension-sensing checkpoint. Mol Biol Cell 2018; 29:2201-2212. [PMID: 29995571 PMCID: PMC6249797 DOI: 10.1091/mbc.e17-12-0701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Multiple interdependent mechanisms ensure faithful segregation of chromosomes during cell division. Among these, the spindle assembly checkpoint monitors attachment of spindle microtubules to the centromere of each chromosome, whereas the tension-sensing checkpoint monitors the opposing forces between sister chromatid centromeres for proper biorientation. We report here a new function for the deeply conserved Gcn5 acetyltransferase in the centromeric localization of Rts1, a key player in the tension-sensing checkpoint. Rts1 is a regulatory component of protein phopshatase 2A, a near universal phosphatase complex, which is recruited to centromeres by the Shugoshin (Sgo) checkpoint component under low-tension conditions to maintain sister chromatid cohesion. We report that loss of Gcn5 disrupts centromeric localization of Rts1. Increased RTS1 dosage robustly suppresses gcn5∆ cell cycle and chromosome segregation defects, including restoration of Rts1 to centromeres. Sgo1’s Rts1-binding function also plays a key role in RTS1 dosage suppression of gcn5∆ phenotypes. Notably, we have identified residues of the centromere histone H3 variant Cse4 that function in these chromosome segregation-related roles of RTS1. Together, these findings expand the understanding of the mechanistic roles of Gcn5 and Cse4 in chromosome segregation.
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Affiliation(s)
- Emily L Petty
- Division of Biological Sciences, Molecular Biology, UCSD Moores Cancer Center, University of California, San Diego, La Jolla, CA 92103
| | - Masha Evpak
- Division of Biological Sciences, Molecular Biology, UCSD Moores Cancer Center, University of California, San Diego, La Jolla, CA 92103
| | - Lorraine Pillus
- Division of Biological Sciences, Molecular Biology, UCSD Moores Cancer Center, University of California, San Diego, La Jolla, CA 92103
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36
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Modulation of TORC2 Signaling by a Conserved Lkb1 Signaling Axis in Budding Yeast. Genetics 2018; 210:155-170. [PMID: 29986907 DOI: 10.1534/genetics.118.301296] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 06/29/2018] [Indexed: 01/03/2023] Open
Abstract
Nutrient availability, growth rate, and cell size are closely linked. For example, in budding yeast, the rate of cell growth is proportional to nutrient availability, cell size is proportional to growth rate, and growth rate is proportional to cell size. Thus, cells grow slowly in poor nutrients and are nearly half the size of cells growing in rich nutrients. Moreover, large cells grow faster than small cells. A signaling network that surrounds TOR kinase complex 2 (TORC2) plays an important role in enforcing these proportional relationships. Cells that lack components of the TORC2 network fail to modulate their growth rate or size in response to changes in nutrient availability. Here, we show that budding yeast homologs of the Lkb1 tumor suppressor kinase are required for normal modulation of TORC2 signaling in response to changes in carbon source. Lkb1 kinases activate Snf1/AMPK to initiate transcription of genes required for utilization of poor carbon sources. However, Lkb1 influences TORC2 signaling via a novel pathway that is independent of Snf1/AMPK. Of the three Lkb1 homologs in budding yeast, Elm1 plays the most important role in modulating TORC2. Elm1 activates a pair of related kinases called Gin4 and Hsl1. Previous work found that loss of Gin4 and Hsl1 causes cells to undergo unrestrained growth during a prolonged mitotic arrest, which suggests that they play a role in linking cell cycle progression to cell growth. We found that Gin4 and Hsl1 also control the TORC2 network. In addition, Gin4 and Hsl1 are themselves influenced by signals from the TORC2 network, consistent with previous work showing that the TORC2 network constitutes a feedback loop. Together, the data suggest a model in which the TORC2 network sets growth rate in response to carbon source, while also relaying signals via Gin4 and Hsl1 that set the critical amount of growth required for cell cycle progression. This kind of close linkage between control of cell growth and size would suggest a simple mechanistic explanation for the proportional relationship between cell size and growth rate.
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Mao Z, Liu C, Lin X, Sun B, Su C. PPP2R5A: A multirole protein phosphatase subunit in regulating cancer development. Cancer Lett 2018; 414:222-229. [DOI: 10.1016/j.canlet.2017.11.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 11/20/2017] [Accepted: 11/21/2017] [Indexed: 12/21/2022]
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Lucena R, Alcaide-Gavilán M, Schubert K, He M, Domnauer MG, Marquer C, Klose C, Surma MA, Kellogg DR. Cell Size and Growth Rate Are Modulated by TORC2-Dependent Signals. Curr Biol 2017; 28:196-210.e4. [PMID: 29290562 DOI: 10.1016/j.cub.2017.11.069] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 10/19/2017] [Accepted: 11/30/2017] [Indexed: 02/05/2023]
Abstract
The size of all cells, from bacteria to vertebrates, is proportional to the growth rate set by nutrient availability, but the underlying mechanisms are unknown. Here, we show that nutrients modulate cell size and growth rate via the TORC2 signaling network in budding yeast. An important function of the TORC2 network is to modulate synthesis of ceramide lipids, which play roles in signaling. TORC2-dependent control of ceramide signaling strongly influences both cell size and growth rate. Thus, cells that cannot make ceramides fail to modulate their growth rate or size in response to changes in nutrients. PP2A associated with the Rts1 regulatory subunit (PP2ARts1) is embedded in a feedback loop that controls TORC2 signaling and helps set the level of TORC2 signaling to match nutrient availability. Together, the data suggest a model in which growth rate and cell size are mechanistically linked by ceramide-dependent signals arising from the TORC2 network.
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Affiliation(s)
- Rafael Lucena
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Maria Alcaide-Gavilán
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Katherine Schubert
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Maybo He
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Matthew G Domnauer
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Catherine Marquer
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA
| | | | | | - Douglas R Kellogg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
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Leitao RM, Kellogg DR. The duration of mitosis and daughter cell size are modulated by nutrients in budding yeast. J Cell Biol 2017; 216:3463-3470. [PMID: 28939614 PMCID: PMC5674877 DOI: 10.1083/jcb.201609114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 06/11/2017] [Accepted: 08/23/2017] [Indexed: 02/06/2023] Open
Abstract
The size of nearly all cells is modulated by nutrients. Thus, cells growing in poor nutrients can be nearly half the size of cells in rich nutrients. In budding yeast, cell size is thought to be controlled almost entirely by a mechanism that delays cell cycle entry until sufficient growth has occurred in G1 phase. Here, we show that most growth of a new daughter cell occurs in mitosis. When the rate of growth is slowed by poor nutrients, the duration of mitosis is increased, which suggests that cells compensate for slow growth in mitosis by increasing the duration of growth. The amount of growth required to complete mitosis is reduced in poor nutrients, leading to a large reduction in cell size. Together, these observations suggest that mechanisms that control the extent of growth in mitosis play a major role in cell size control in budding yeast.
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Affiliation(s)
- Ricardo M Leitao
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA
| | - Douglas R Kellogg
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA
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40
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Chandler-Brown D, Schmoller KM, Winetraub Y, Skotheim JM. The Adder Phenomenon Emerges from Independent Control of Pre- and Post-Start Phases of the Budding Yeast Cell Cycle. Curr Biol 2017; 27:2774-2783.e3. [PMID: 28889980 DOI: 10.1016/j.cub.2017.08.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/16/2017] [Accepted: 08/04/2017] [Indexed: 12/26/2022]
Abstract
Although it has long been clear that cells actively regulate their size, the molecular mechanisms underlying this regulation have remained poorly understood. In budding yeast, cell size primarily modulates the duration of the cell-division cycle by controlling the G1/S transition known as Start. We have recently shown that the rate of progression through Start increases with cell size, because cell growth dilutes the cell-cycle inhibitor Whi5 in G1. Recent phenomenological studies in yeast and bacteria have shown that these cells add an approximately constant volume during each complete cell cycle, independent of their size at birth. These results seem to be in conflict, as the phenomenological studies suggest that cells measure the amount they grow, rather than their size, and that size control acts over the whole cell cycle, rather than specifically in G1. Here, we propose an integrated model that unifies the adder phenomenology with the molecular mechanism of G1/S cell-size control. We use single-cell microscopy to parameterize a full cell-cycle model based on independent control of pre- and post-Start cell-cycle periods. We find that our model predicts the size-independent amount of cell growth during the full cell cycle. This suggests that the adder phenomenon is an emergent property of the independent regulation of pre- and post-Start cell-cycle periods rather than the consequence of an underlying molecular mechanism measuring a fixed amount of growth.
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Affiliation(s)
| | - Kurt M Schmoller
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | | | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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41
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Clarke J, Dephoure N, Horecka I, Gygi S, Kellogg D. A conserved signaling network monitors delivery of sphingolipids to the plasma membrane in budding yeast. Mol Biol Cell 2017; 28:2589-2599. [PMID: 28794263 PMCID: PMC5620368 DOI: 10.1091/mbc.e17-01-0081] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 07/28/2017] [Accepted: 08/02/2017] [Indexed: 12/16/2022] Open
Abstract
In budding yeast, signals generated in response to membrane growth are required for cell cycle progression. A mass spectrometry screen for signals triggered by an arrest of membrane growth identified sphingolipid signaling pathways. Delivery of sphingolipids to the plasma membrane could generate signals that control cell growth and the cell cycle. In budding yeast, cell cycle progression and ribosome biogenesis are dependent on plasma membrane growth, which ensures that events of cell growth are coordinated with each other and with the cell cycle. However, the signals that link the cell cycle and ribosome biogenesis to membrane growth are poorly understood. Here we used proteome-wide mass spectrometry to systematically discover signals associated with membrane growth. The results suggest that membrane trafficking events required for membrane growth generate sphingolipid-dependent signals. A conserved signaling network appears to play an essential role in signaling by responding to delivery of sphingolipids to the plasma membrane. In addition, sphingolipid-dependent signals control phosphorylation of protein kinase C (Pkc1), which plays an essential role in the pathways that link the cell cycle and ribosome biogenesis to membrane growth. Together these discoveries provide new clues as to how growth-dependent signals control cell growth and the cell cycle.
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Affiliation(s)
- Jesse Clarke
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Noah Dephoure
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10021
| | - Ira Horecka
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Steven Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Douglas Kellogg
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
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42
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Talarek N, Gueydon E, Schwob E. Homeostatic control of START through negative feedback between Cln3-Cdk1 and Rim15/Greatwall kinase in budding yeast. eLife 2017; 6. [PMID: 28600888 PMCID: PMC5484617 DOI: 10.7554/elife.26233] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/10/2017] [Indexed: 12/30/2022] Open
Abstract
How cells coordinate growth and division is key for size homeostasis. Phosphorylation by G1-CDK of Whi5/Rb inhibitors of SBF/E2F transcription factors triggers irreversible S-phase entry in yeast and metazoans, but why this occurs at a given cell size is not fully understood. We show that the yeast Rim15-Igo1,2 pathway, orthologous to Gwl-Arpp19/ENSA, is up-regulated in early G1 and helps promoting START by preventing PP2ACdc55 to dephosphorylate Whi5. RIM15 overexpression lowers cell size while IGO1,2 deletion delays START in cells with low CDK activity. Deletion of WHI5, CDC55 and ectopic CLN2 expression suppress the START delay of igo1,2∆ cells. Rim15 activity increases after cells switch from fermentation to respiration, where Igo1,2 contribute to chromosome maintenance. Interestingly Cln3-Cdk1 also inhibits Rim15 activity, which enables homeostatic control of Whi5 phosphorylation and cell cycle entry. We propose that Rim15/Gwl regulation of PP2A plays a hitherto unappreciated role in cell size homeostasis during metabolic rewiring of the cell cycle. DOI:http://dx.doi.org/10.7554/eLife.26233.001
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Affiliation(s)
| | | | - Etienne Schwob
- IGMM, CNRS, University of Montpellier, Montpellier, France
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43
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Deng L, Lee ME, Schutt KL, Moseley JB. Phosphatases Generate Signal Specificity Downstream of Ssp1 Kinase in Fission Yeast. Mol Cell Biol 2017; 37:e00494-16. [PMID: 28223368 PMCID: PMC5477550 DOI: 10.1128/mcb.00494-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 10/10/2016] [Accepted: 02/13/2017] [Indexed: 11/20/2022] Open
Abstract
AMPK-related protein kinases (ARKs) coordinate cell growth, proliferation, and migration with environmental status. It is unclear how specific ARKs are activated at specific times. In the fission yeast Schizosaccharomyces pombe, the CaMKK-like protein kinase Ssp1 promotes cell cycle progression by activating the ARK Cdr2 according to cell growth signals. Here, we demonstrate that Ssp1 activates a second ARK, Ssp2/AMPKα, for cell proliferation in low environmental glucose. Ssp1 activates these two related targets by the same biochemical mechanism: direct phosphorylation of a conserved residue in the activation loop (Cdr2-T166 and Ssp2-T189). Despite a shared upstream kinase and similar phosphorylation sites, Cdr2 and Ssp2 have distinct regulatory input cues and distinct functional outputs. We investigated this specificity and found that distinct protein phosphatases counteract Ssp1 activity toward its different substrates. We identified the PP6 family phosphatase Ppe1 as the primary phosphatase for Ssp2-T189 dephosphorylation. The phosphatase inhibitor Sds23 acts upstream of PP6 to regulate Ssp2-T189 phosphorylation in a manner that depends on energy but not on the intact AMPK heterotrimer. In contrast, Cdr2-T166 phosphorylation is regulated by protein phosphatase 2A but not by the Sds23-PP6 pathway. Thus, our study provides a phosphatase-driven mechanism to induce specific physiological responses downstream of a master protein kinase.
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Affiliation(s)
- Lin Deng
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Mid Eum Lee
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Katherine L Schutt
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - James B Moseley
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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Promotion of Cell Viability and Histone Gene Expression by the Acetyltransferase Gcn5 and the Protein Phosphatase PP2A in Saccharomyces cerevisiae. Genetics 2016; 203:1693-707. [PMID: 27317677 DOI: 10.1534/genetics.116.189506] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 05/27/2016] [Indexed: 01/23/2023] Open
Abstract
Histone modifications direct chromatin-templated events in the genome and regulate access to DNA sequence information. There are multiple types of modifications, and a common feature is their dynamic nature. An essential step for understanding their regulation, therefore, lies in characterizing the enzymes responsible for adding and removing histone modifications. Starting with a dosage-suppressor screen in Saccharomyces cerevisiae, we have discovered a functional interaction between the acetyltransferase Gcn5 and the protein phosphatase 2A (PP2A) complex, two factors that regulate post-translational modifications. We find that RTS1, one of two genes encoding PP2A regulatory subunits, is a robust and specific high-copy suppressor of temperature sensitivity of gcn5∆ and a subset of other gcn5∆ phenotypes. Conversely, loss of both PP2A(Rts1) and Gcn5 function in the SAGA and SLIK/SALSA complexes is lethal. RTS1 does not restore global transcriptional defects in gcn5∆; however, histone gene expression is restored, suggesting that the mechanism of RTS1 rescue includes restoration of specific cell cycle transcripts. Pointing to new mechanisms of acetylation-phosphorylation cross-talk, RTS1 high-copy rescue of gcn5∆ growth requires two residues of H2B that are phosphorylated in human cells. These data highlight the potential significance of dynamic phosphorylation and dephosphorylation of these deeply conserved histone residues for cell viability.
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45
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Palumbo P, Vanoni M, Cusimano V, Busti S, Marano F, Manes C, Alberghina L. Whi5 phosphorylation embedded in the G1/S network dynamically controls critical cell size and cell fate. Nat Commun 2016; 7:11372. [PMID: 27094800 PMCID: PMC4843020 DOI: 10.1038/ncomms11372] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 03/18/2016] [Indexed: 01/23/2023] Open
Abstract
In budding yeast, overcoming of a critical size to enter S phase and the mitosis/mating switch--two central cell fate events--take place in the G1 phase of the cell cycle. Here we present a mathematical model of the basic molecular mechanism controlling the G1/S transition, whose major regulatory feature is multisite phosphorylation of nuclear Whi5. Cln3-Cdk1, whose nuclear amount is proportional to cell size, and then Cln1,2-Cdk1, randomly phosphorylate both decoy and functional Whi5 sites. Full phosphorylation of functional sites releases Whi5 inhibitory activity, activating G1/S transcription. Simulation analysis shows that this mechanism ensures coherent release of Whi5 inhibitory action and accounts for many experimentally observed properties of mitotically growing or conjugating G1 cells. Cell cycle progression and transcriptional analyses of a Whi5 phosphomimetic mutant verify the model prediction that coherent transcription of the G1/S regulon and ensuing G1/S transition requires full phosphorylation of Whi5 functional sites.
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Affiliation(s)
- Pasquale Palumbo
- SYSBIO.IT Center for Systems Biology, Italy.,CNR-IASI, Italian National Research Council - Institute for Systems Analysis and Computer Science, Via dei Taurini 19, 00185 Rome, Italy
| | - Marco Vanoni
- SYSBIO.IT Center for Systems Biology, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Valerio Cusimano
- SYSBIO.IT Center for Systems Biology, Italy.,CNR-IASI, Italian National Research Council - Institute for Systems Analysis and Computer Science, Via dei Taurini 19, 00185 Rome, Italy
| | - Stefano Busti
- SYSBIO.IT Center for Systems Biology, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Francesca Marano
- SYSBIO.IT Center for Systems Biology, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Costanzo Manes
- CNR-IASI, Italian National Research Council - Institute for Systems Analysis and Computer Science, Via dei Taurini 19, 00185 Rome, Italy.,Department of Information Engineering, Computer Science and Mathematics, University of L'Aquila, Via Vetoio, 67100 Coppito (L'Aquila), Italy
| | - Lilia Alberghina
- SYSBIO.IT Center for Systems Biology, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
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46
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Abstract
Cells of a given type maintain a characteristic cell size to function efficiently in their ecological or organismal context. They achieve this through the regulation of growth rates or by actively sensing size and coupling this signal to cell division. We focus this review on potential size-sensing mechanisms, including geometric, external cue, and titration mechanisms. Mechanisms that titrate proteins against DNA are of particular interest because they are consistent with the robust correlation of DNA content and cell size. We review the literature, which suggests that titration mechanisms may underlie cell-size sensing in Xenopus embryos, budding yeast, and Escherichia coli, whereas alternative mechanisms may function in fission yeast.
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Affiliation(s)
- Amanda A Amodeo
- Department of Biology, Stanford University, Stanford, California 94305
| | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, California 94305
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47
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Li Y, Liu D, López-Paz C, Olson BJ, Umen JG. A new class of cyclin dependent kinase in Chlamydomonas is required for coupling cell size to cell division. eLife 2016; 5:e10767. [PMID: 27015111 PMCID: PMC4841777 DOI: 10.7554/elife.10767] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 03/24/2016] [Indexed: 01/04/2023] Open
Abstract
Proliferating cells actively control their size by mechanisms that are poorly understood. The unicellular green alga Chlamydomonas reinhardtii divides by multiple fission, wherein a ‘counting’ mechanism couples mother cell-size to cell division number allowing production of uniform-sized daughters. We identified a sizer protein, CDKG1, that acts through the retinoblastoma (RB) tumor suppressor pathway as a D-cyclin-dependent RB kinase to regulate mitotic counting. Loss of CDKG1 leads to fewer mitotic divisions and large daughters, while mis-expression of CDKG1 causes supernumerous mitotic divisions and small daughters. The concentration of nuclear-localized CDKG1 in pre-mitotic cells is set by mother cell size, and its progressive dilution and degradation with each round of cell division may provide a link between mother cell-size and mitotic division number. Cell-size-dependent accumulation of limiting cell cycle regulators such as CDKG1 is a potentially general mechanism for size control. DOI:http://dx.doi.org/10.7554/eLife.10767.001 Most cells are programmed to maintain a certain size. This property, known as size control, is achieved by balancing growth and division, such that a cell will only divide after it reaches a certain size. However, and despite years of research, it is largely unknown how cells sense their size (or growth) to be able to divide accordingly. One theory proposes that there is a “sizer” protein inside cells, and that cells measure the abundance of this protein and use it to link cell size to the process of division. However, the existence of such a protein remained unproven. Li, Liu et al. have now used the cells of the green alga Chlamydomonas to identify a candidate sizer protein. Chlamydomonas cells, like many other algae, can grow to become very large mother cells that then divide one or more times in succession to produce many daughter cells. Larger mother cells undergo more divisions than smaller mother cells in order to produce daughter cells of a correct size. Using a range of genetic and biochemical techniques, Li, Liu et al. identified a protein that is produced in Chlamydomonas cells just before they begin to divide. Larger mother cells contain more of this protein than smaller cells and the protein encourages cells to divide. For example, mutant cells that lack this protein divided too few times, while cells that produce too much of it divided too many times. The protein, called CDKG1, belongs to a family of proteins that regulate cell division in many organisms. CDKG1 is a kinase – an enzyme that alters the activity of other proteins by adding a phosphate group on to them. In Chlamydomonas, CDKG1 couples cell size to cell division by altering the activity of an important protein called the retinoblastoma-related protein that controls cell division in numerous organisms. This protein is also frequently disrupted in cancers in humans. These findings shed new light on a molecular pathway for size control. Future work will need to determine how the accumulation of CDKG1 links to the size of a mother cell and how it is inactivated once daughter cells reach the appropriate size. DOI:http://dx.doi.org/10.7554/eLife.10767.002
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Affiliation(s)
- Yubing Li
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.,Plant Molecular and Cell Biology Program, the Horticultural and Plant Science Department, University of Florida, Gainesville, United States
| | - Dianyi Liu
- Donald Danforth Plant Science Center, St. Louis, United States
| | - Cristina López-Paz
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.,Donald Danforth Plant Science Center, St. Louis, United States
| | - Bradley Jsc Olson
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - James G Umen
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.,Donald Danforth Plant Science Center, St. Louis, United States
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48
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Vuković LD, Jevtić P, Edens LJ, Levy DL. New Insights into Mechanisms and Functions of Nuclear Size Regulation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 322:1-59. [PMID: 26940517 DOI: 10.1016/bs.ircmb.2015.11.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nuclear size is generally maintained within a defined range in a given cell type. Changes in cell size that occur during cell growth, development, and differentiation are accompanied by dynamic nuclear size adjustments in order to establish appropriate nuclear-to-cytoplasmic volume relationships. It has long been recognized that aberrations in nuclear size are associated with certain disease states, most notably cancer. Nuclear size and morphology must impact nuclear and cellular functions. Understanding these functional implications requires an understanding of the mechanisms that control nuclear size. In this review, we first provide a general overview of the diverse cellular structures and activities that contribute to nuclear size control, including structural components of the nucleus, effects of DNA amount and chromatin compaction, signaling, and transport pathways that impinge on the nucleus, extranuclear structures, and cell cycle state. We then detail some of the key mechanistic findings about nuclear size regulation that have been gleaned from a variety of model organisms. Lastly, we review studies that have implicated nuclear size in the regulation of cell and nuclear function and speculate on the potential functional significance of nuclear size in chromatin organization, gene expression, nuclear mechanics, and disease. With many fundamental cell biological questions remaining to be answered, the field of nuclear size regulation is still wide open.
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Affiliation(s)
- Lidija D Vuković
- Department of Molecular Biology, University of Wyoming, Laramie, WY, United States of America
| | - Predrag Jevtić
- Department of Molecular Biology, University of Wyoming, Laramie, WY, United States of America
| | - Lisa J Edens
- Department of Molecular Biology, University of Wyoming, Laramie, WY, United States of America
| | - Daniel L Levy
- Department of Molecular Biology, University of Wyoming, Laramie, WY, United States of America.
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49
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Redundant Regulation of Cdk1 Tyrosine Dephosphorylation in Saccharomyces cerevisiae. Genetics 2015; 202:903-10. [PMID: 26715668 DOI: 10.1534/genetics.115.182469] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/21/2015] [Indexed: 11/18/2022] Open
Abstract
Cdk1 activity drives both mitotic entry and the metaphase-to-anaphase transition in all eukaryotes. The kinase Wee1 and the phosphatase Cdc25 regulate the mitotic activity of Cdk1 by the reversible phosphorylation of a conserved tyrosine residue. Mutation of cdc25 in Schizosaccharomyces pombe blocks Cdk1 dephosphorylation and causes cell cycle arrest. In contrast, deletion of MIH1, the cdc25 homolog in Saccharomyces cerevisiae, is viable. Although Cdk1-Y19 phosphorylation is elevated during mitosis in mih1∆ cells, Cdk1 is dephosphorylated as cells progress into G1, suggesting that additional phosphatases regulate Cdk1 dephosphorylation. Here we show that the phosphatase Ptp1 also regulates Cdk1 dephosphorylation in vivo and can directly dephosphorylate Cdk1 in vitro. Using a novel in vivo phosphatase assay, we also show that PP2A bound to Rts1, the budding yeast B56-regulatory subunit, regulates dephosphorylation of Cdk1 independently of a function regulating Swe1, Mih1, or Ptp1, suggesting that PP2A(Rts1) either directly dephosphorylates Cdk1-Y19 or regulates an unidentified phosphatase.
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50
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Lucena R, Dephoure N, Gygi SP, Kellogg DR, Tallada VA, Daga RR, Jimenez J. Nucleocytoplasmic transport in the midzone membrane domain controls yeast mitotic spindle disassembly. ACTA ACUST UNITED AC 2015; 209:387-402. [PMID: 25963819 PMCID: PMC4427787 DOI: 10.1083/jcb.201412144] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
During anaphase B, Imp1-mediated transport of the AAA-ATPase Cdc48 protein at the membrane domain surrounding the mitotic spindle midzone promotes spindle midzone dissolution in fission yeast. During each cell cycle, the mitotic spindle is efficiently assembled to achieve chromosome segregation and then rapidly disassembled as cells enter cytokinesis. Although much has been learned about assembly, how spindles disassemble at the end of mitosis remains unclear. Here we demonstrate that nucleocytoplasmic transport at the membrane domain surrounding the mitotic spindle midzone, here named the midzone membrane domain (MMD), is essential for spindle disassembly in Schizosaccharomyces pombe cells. We show that, during anaphase B, Imp1-mediated transport of the AAA-ATPase Cdc48 protein at the MMD allows this disassembly factor to localize at the spindle midzone, thereby promoting spindle midzone dissolution. Our findings illustrate how a separate membrane compartment supports spindle disassembly in the closed mitosis of fission yeast.
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Affiliation(s)
- Rafael Lucena
- Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide/Consejo Superior de Investigaciones Cientificas, 41013 Sevilla, Spain Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Noah Dephoure
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Steve P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Douglas R Kellogg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Victor A Tallada
- Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide/Consejo Superior de Investigaciones Cientificas, 41013 Sevilla, Spain
| | - Rafael R Daga
- Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide/Consejo Superior de Investigaciones Cientificas, 41013 Sevilla, Spain
| | - Juan Jimenez
- Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide/Consejo Superior de Investigaciones Cientificas, 41013 Sevilla, Spain
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