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Vázquez-Bolado A, López-San Segundo R, García-Blanco N, Rozalén AE, González-Álvarez D, Suárez MB, Pérez-Hidalgo L, Moreno S. The Greatwall-Endosulfine Switch Accelerates Autophagic Flux during the Cell Divisions Leading to G1 Arrest and Entry into Quiescence in Fission Yeast. Int J Mol Sci 2022; 24:ijms24010148. [PMID: 36613592 PMCID: PMC9820488 DOI: 10.3390/ijms24010148] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Entry into quiescence in the fission yeast Schizosaccharomyces pombe is induced by nitrogen starvation. In the absence of nitrogen, proliferating fission yeast cells divide twice without cell growth and undergo cell cycle arrest in G1 before becoming G0 quiescent cells. Under these conditions, autophagy is induced to produce enough nitrogen for the two successive cell divisions that take place before the G1 arrest. In parallel to the induction of autophagy, the Greatwall-Endosulfine switch is activated upon nitrogen starvation to down-regulate protein phosphatase PP2A/B55 activity, which is essential for cell cycle arrest in G1 and implementation of the quiescent program. Here we show that, although inactivation of PP2A/B55 by the Greatwall-Endosulfine switch is not required to promote autophagy initiation, it increases autophagic flux at least in part by upregulating the expression of a number of autophagy-related genes.
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Affiliation(s)
- Alicia Vázquez-Bolado
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Salamanca University, Zacarías González 2, 37007 Salamanca, Spain
| | - Rafael López-San Segundo
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Salamanca University, Zacarías González 2, 37007 Salamanca, Spain
| | - Natalia García-Blanco
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Salamanca University, Zacarías González 2, 37007 Salamanca, Spain
| | - Ana Elisa Rozalén
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Salamanca University, Zacarías González 2, 37007 Salamanca, Spain
| | - Daniel González-Álvarez
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Salamanca University, Zacarías González 2, 37007 Salamanca, Spain
| | - M. Belén Suárez
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Salamanca University, Zacarías González 2, 37007 Salamanca, Spain
- Department of Microbiology and Genetics, Salamanca University, 37007 Salamanca, Spain
| | - Livia Pérez-Hidalgo
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Salamanca University, Zacarías González 2, 37007 Salamanca, Spain
| | - Sergio Moreno
- Instituto de Biología Funcional y Genómica (IBFG), CSIC, Salamanca University, Zacarías González 2, 37007 Salamanca, Spain
- Correspondence:
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Regulation of inorganic polyphosphate is required for proper vacuolar proteolysis in fission yeast. J Biol Chem 2021; 297:100891. [PMID: 34147496 PMCID: PMC8294586 DOI: 10.1016/j.jbc.2021.100891] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 06/07/2021] [Accepted: 06/16/2021] [Indexed: 02/08/2023] Open
Abstract
Regulation of cellular proliferation and quiescence is a central issue in biology that has been studied using model unicellular eukaryotes, such as the fission yeast Schizosaccharomyces pombe. We previously reported that the ubiquitin/proteasome pathway and autophagy are essential to maintain quiescence induced by nitrogen deprivation in S. pombe; however, specific ubiquitin ligases that maintain quiescence are not fully understood. Here we investigated the SPX-RING-type ubiquitin ligase Pqr1, identified as required for quiescence in a genetic screen. Pqr1 is found to be crucial for vacuolar proteolysis, the final step of autophagy, through proper regulation of phosphate and its polymer polyphosphate. Pqr1 restricts phosphate uptake into the cell through ubiquitination and subsequent degradation of phosphate transporters on plasma membranes. We hypothesized that Pqr1 may act as the central regulator for phosphate control in S. pombe, through the function of the SPX domain involved in phosphate sensing. Deletion of pqr1+ resulted in hyperaccumulation of intracellular phosphate and polyphosphate and in improper autophagy-dependent proteolysis under conditions of nitrogen starvation. Polyphosphate hyperaccumulation in pqr1+-deficient cells was mediated by the polyphosphate synthase VTC complex in vacuoles. Simultaneous deletion of VTC complex subunits rescued Pqr1 mutant phenotypes, including defects in proteolysis and loss of viability during quiescence. We conclude that excess polyphosphate may interfere with proteolysis in vacuoles by mechanisms that as yet remain unknown. The present results demonstrate a connection between polyphosphate metabolism and vacuolar functions for proper autophagy-dependent proteolysis, and we propose that polyphosphate homeostasis contributes to maintenance of cellular viability during quiescence.
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Matsuda S, Kikkawa U, Uda H, Nakashima A. The S. pombe CDK5 ortholog Pef1 regulates sexual differentiation through control of the TORC1 pathway and autophagy. J Cell Sci 2020; 133:jcs247817. [PMID: 32788233 DOI: 10.1242/jcs.247817] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 07/20/2020] [Indexed: 12/17/2022] Open
Abstract
In Schizosaccharomyces pombe, a general strategy for survival in response to environmental changes is sexual differentiation, which is triggered by TORC1 inactivation. However, mechanisms of TORC1 regulation in fission yeast remain poorly understood. In this study, we found that Pef1, which is an ortholog of mammalian CDK5, regulates the initiation of sexual differentiation through positive regulation of TORC1 activity. Conversely, deletion of pef1 leads to activation of autophagy and subsequent excessive TORC1 reactivation during the early phases of the nitrogen starvation response. This excessive TORC1 reactivation results in the silencing of the Ste11-Mei2 pathway and mating defects. Additionally, we found that pef1 genetically interacts with tsc1 and tsc2 for TORC1 regulation, and physically interacts with three cyclins, Clg1, Pas1 and Psl1. The double deletion of clg1 and pas1 promotes activation of autophagy and TORC1 during nitrogen starvation, similar to what is seen in pef1Δ cells. Overall, our work suggests that Pef1-Clg1 and Pef1-Pas1 complexes regulate initiation of sexual differentiation through control of the TSC-TORC1 pathway and autophagy.
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Affiliation(s)
- Shinya Matsuda
- Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
- Department of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, 422-8526, Japan
| | - Ushio Kikkawa
- Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe, 657-8501, Japan
| | - Haruka Uda
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe, 657-8501, Japan
| | - Akio Nakashima
- Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe, 657-8501, Japan
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García-Blanco N, Vázquez-Bolado A, Moreno S. Greatwall-Endosulfine: A Molecular Switch that Regulates PP2A/B55 Protein Phosphatase Activity in Dividing and Quiescent Cells. Int J Mol Sci 2019; 20:ijms20246228. [PMID: 31835586 PMCID: PMC6941129 DOI: 10.3390/ijms20246228] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/02/2019] [Accepted: 12/05/2019] [Indexed: 12/13/2022] Open
Abstract
During the cell cycle, hundreds of proteins become phosphorylated and dephosphorylated, indicating that protein kinases and protein phosphatases play a central role in its regulation. It has been widely recognized that oscillation in cyclin-dependent kinase (CDK) activity promotes DNA replication, during S-phase, and chromosome segregation, during mitosis. Each CDK substrate phosphorylation status is defined by the balance between CDKs and CDK-counteracting phosphatases. In fission yeast and animal cells, PP2A/B55 is the main protein phosphatase that counteracts CDK activity. PP2A/B55 plays a key role in mitotic entry and mitotic exit, and it is regulated by the Greatwall-Endosulfine (ENSA) molecular switch that inactivates PP2A/B55 at the onset of mitosis, allowing maximal CDK activity at metaphase. The Greatwall-ENSA-PP2A/B55 pathway is highly conserved from yeast to animal cells. In yeasts, Greatwall is negatively regulated by nutrients through TORC1 and S6 kinase, and couples cell growth, regulated by TORC1, to cell cycle progression, driven by CDK activity. In animal cells, Greatwall is phosphorylated and activated by Cdk1 at G2/M, generating a bistable molecular switch that results in full activation of Cdk1/CyclinB. Here we review the current knowledge of the Greatwall-ENSA-PP2A/B55 pathway and discuss its role in cell cycle progression and as an integrator of nutritional cues.
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Chen C, Rodriguez Pino M, Haller PR, Verde F. Conserved NDR/LATS kinase controls RAS GTPase activity to regulate cell growth and chronological lifespan. Mol Biol Cell 2019; 30:2598-2616. [PMID: 31390298 PMCID: PMC6740195 DOI: 10.1091/mbc.e19-03-0172] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Adaptation to the nutritional environment is critical for all cells. RAS GTPase is a highly conserved GTP-binding protein with crucial functions for cell growth and differentiation in response to environmental conditions. Here, we describe a novel mechanism connecting RAS GTPase to nutrient availability in fission yeast. We report that the conserved NDR/LATS kinase Orb6 responds to nutritional cues and regulates Ras1 GTPase activity. Orb6 increases the protein levels of an Ras1 GTPase activator, the guanine nucleotide exchange factor Efc25, by phosphorylating Sts5, a protein bound to efc25 mRNA. By manipulating the extent of Orb6-mediated Sts5 assembly into RNP granules, we can modulate Efc25 protein levels, Ras1 GTPase activity, and, as a result, cell growth and cell survival. Thus, we conclude that the Orb6-Sts5-Ras1 regulatory axis plays a crucial role in promoting cell adaptation, balancing the opposing demands of promoting cell growth and extending chronological lifespan.
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Affiliation(s)
- Chuan Chen
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Marbelys Rodriguez Pino
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Patrick Roman Haller
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Fulvia Verde
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136
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Zhang J, Si J, Gan L, Di C, Xie Y, Sun C, Li H, Guo M, Zhang H. Research progress on therapeutic targeting of quiescent cancer cells. ARTIFICIAL CELLS NANOMEDICINE AND BIOTECHNOLOGY 2019; 47:2810-2820. [DOI: 10.1080/21691401.2019.1638793] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jinhua Zhang
- Department of Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jing Si
- Department of Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Lu Gan
- Department of Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Cuixia Di
- Department of Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yi Xie
- Department of Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Chao Sun
- Department of Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Hongyan Li
- Department of Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Menghuan Guo
- School of Pharmacy, Lanzhou University, Lanzhou, China
| | - Hong Zhang
- Department of Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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