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Cohen A, Lubenski L, Mouzon A, Kupiec M, Weisman R. TORC2 is required for the accumulation of γH2A in response to DNA damage. J Biol Chem 2024; 300:107531. [PMID: 38971312 PMCID: PMC11321321 DOI: 10.1016/j.jbc.2024.107531] [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: 01/07/2024] [Revised: 06/16/2024] [Accepted: 06/17/2024] [Indexed: 07/08/2024] Open
Abstract
TOR protein kinases serve as the catalytic subunit of the TORC1 and TORC2 complexes, which regulate cellular growth, proliferation, and survival. In the fission yeast, Schizosaccharomyces pombe, cells lacking TORC2 or its downstream kinase Gad8 (AKT or SGK1 in human cells) exhibit sensitivity to a wide range of stress conditions, including DNA damage stress. One of the first responses to DNA damage is the phosphorylation of C-terminal serine residues within histone H2AX in human cells (γH2AX), or histone H2A in yeast cells (γH2A). The kinases responsible for γH2A in S. pombe are the two DNA damage checkpoint kinases Rad3 and Tel1 (ATR and ATM, respectively, in human cells). Here we report that TORC2-Gad8 signaling is required for accumulation of γH2A in response to DNA damage and during quiescence. Using the TOR-specific inhibitor, Torin1, we demonstrate that the effect of TORC2 on γH2A in response to DNA damage is immediate, rather than adaptive. The lack of γH2A is restored by deletion mutations of transcription and chromatin modification factors, including loss of components of Paf1C, SAGA, Mediator, and the bromo-domain proteins Bdf1/Bdf2. Thus, we suggest that TORC2-Gad8 may affect the accumulation of γH2A by regulating chromatin structure and function.
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Affiliation(s)
- Adiel Cohen
- Department of Natural Sciences, The Open University of Israel, Ranana, Israel
| | - Lea Lubenski
- The Shmunis School of Biomedicine & Cancer Research, Tel Aviv University, Tel Aviv, Israel
| | - Ava Mouzon
- The Shmunis School of Biomedicine & Cancer Research, Tel Aviv University, Tel Aviv, Israel
| | - Martin Kupiec
- The Shmunis School of Biomedicine & Cancer Research, Tel Aviv University, Tel Aviv, Israel
| | - Ronit Weisman
- Department of Natural Sciences, The Open University of Israel, Ranana, Israel.
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2
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Kawamukai M. Regulation of sexual differentiation initiation in Schizosaccharomyces pombe. Biosci Biotechnol Biochem 2024; 88:475-492. [PMID: 38449372 DOI: 10.1093/bbb/zbae019] [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: 01/16/2024] [Accepted: 02/05/2024] [Indexed: 03/08/2024]
Abstract
The fission yeast Schizosaccharomyces pombe is an excellent model organism to explore cellular events owing to rich tools in genetics, molecular biology, cellular biology, and biochemistry. Schizosaccharomyces pombe proliferates continuously when nutrients are abundant but arrests in G1 phase upon depletion of nutrients such as nitrogen and glucose. When cells of opposite mating types are present, cells conjugate, fuse, undergo meiosis, and finally form 4 spores. This sexual differentiation process in S. pombe has been studied extensively. To execute sexual differentiation, the glucose-sensing cAMP-PKA (cyclic adenosine monophosphate-protein kinase A) pathway, nitrogen-sensing TOR (target of rapamycin) pathway, and SAPK (stress-activating protein kinase) pathway are crucial, and the MAPK (mitogen-activating protein kinase) cascade is essential for pheromone sensing. These signals regulate ste11 at the transcriptional and translational levels, and Ste11 is modified in multiple ways. This review summarizes the initiation of sexual differentiation in S. pombe based on results I have helped to obtain, including the work of many excellent researchers.
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Affiliation(s)
- Makoto Kawamukai
- D epartment of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, Nishikawatsu, Matsue, Japan
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3
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Basier C, Nurse P. TOR regulates variability of protein synthesis rates. EMBO J 2024; 43:1618-1633. [PMID: 38499788 PMCID: PMC11021518 DOI: 10.1038/s44318-024-00075-8] [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: 10/23/2023] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 03/20/2024] Open
Abstract
Cellular processes are subject to inherent variability, but the extent to which cells can regulate this variability has received little investigation. Here, we explore the characteristics of the rate of cellular protein synthesis in single cells of the eukaryote fission yeast. Strikingly, this rate is highly variable despite protein synthesis being dependent on hundreds of reactions which might be expected to average out at the overall cellular level. The rate is variable over short time scales, and exhibits homoeostatic behaviour at the population level. Cells can regulate the level of variability through processes involving the TOR pathway, suggesting there is an optimal level of variability conferring a selective advantage. While this could be an example of bet-hedging, but we propose an alternative explanation: regulated 'loose' control of complex processes of overall cellular metabolism such as protein synthesis, may lead to this variability. This could ensure cells are fluid in control and agile in response to changing conditions, and may constitute a novel organisational principle of complex metabolic cellular systems.
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Affiliation(s)
- Clovis Basier
- Cell Cycle Laboratory, The Francis Crick Institute, London, NW1 1AT, UK.
| | - Paul Nurse
- Cell Cycle Laboratory, The Francis Crick Institute, London, NW1 1AT, UK
- Laboratory of Yeast Genetics and Cell Biology, Rockefeller University, New York, NY, 10065, USA
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4
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Wang L, Zhang X, Li L, Bao J, Lin F, Zhu X. A key sphingolipid pathway gene, MoDES1, regulates conidiation, virulence and plasma membrane tension in Magnaporthe oryzae. Microbiol Res 2024; 279:127554. [PMID: 38056173 DOI: 10.1016/j.micres.2023.127554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/08/2023] [Accepted: 11/20/2023] [Indexed: 12/08/2023]
Abstract
Rice blast, caused by the plant pathogenic fungus Magnaporthe oryzae, is a destructive disaster all over the earth that causes enormous losses in crop production. Sphingolipid, an important biological cell membrane lipid, is an essential structural component in the plasma membrane (PM) and has several biological functions, including cell mitosis, apoptosis, stress resistance, and signal transduction. Previous studies have suggested that sphingolipid and its derivatives play essential roles in the virulence of plant pathogenic fungi. However, the functions of sphingolipid biosynthesis-related proteins are not fully understood. In this article, we identified a key sphingolipid synthesis enzyme, MoDes1, and found that it is engaged in cell development and pathogenicity in M. oryzae. Deletion of MoDES1 gave rise to pleiotropic defects in vegetative growth, conidiation, plant penetration, and pathogenicity. MoDes1 is also required for lipid homeostasis and participates in the cell wall integrity (CWI) and Osm1-MAPK pathways. Notably, our results showed that there is negative feedback in the TORC2 signaling pathway to compensate for the decreased sphingolipid level due to the knockout of MoDES1 by regulating the phosphorylated Ypk1 level and PM tension. Furthermore, protein structure building has shown that MoDes1 is a potential drug target. These findings further refine the function of Des1 and deepen our understanding of the sphingolipid biosynthesis pathway in M. oryzae, laying a foundation for developing novel and specific drugs for rice blast control.
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Affiliation(s)
- Lei Wang
- The College of Advanced Agricultural Sciences, Zhejiang Agriculture and Forest University, Hangzhou 311300, China
| | - Xiaozhi Zhang
- The College of Advanced Agricultural Sciences, Zhejiang Agriculture and Forest University, Hangzhou 311300, China
| | - Lin Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Jiandong Bao
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Fucheng Lin
- The College of Advanced Agricultural Sciences, Zhejiang Agriculture and Forest University, Hangzhou 311300, China; State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; Xianghu Laboratory, Hangzhou, 311231, China.
| | - Xueming Zhu
- The College of Advanced Agricultural Sciences, Zhejiang Agriculture and Forest University, Hangzhou 311300, China; State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
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5
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Morozumi Y, Mahayot F, Nakase Y, Soong JX, Yamawaki S, Sofyantoro F, Imabata Y, Oda AH, Tamura M, Kofuji S, Akikusa Y, Shibatani A, Ohta K, Shiozaki K. Rapamycin-sensitive mechanisms confine the growth of fission yeast below the temperatures detrimental to cell physiology. iScience 2024; 27:108777. [PMID: 38269097 PMCID: PMC10805665 DOI: 10.1016/j.isci.2023.108777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 10/12/2023] [Accepted: 12/22/2023] [Indexed: 01/26/2024] Open
Abstract
Cells cease to proliferate above their growth-permissible temperatures, a ubiquitous phenomenon generally attributed to heat damage to cellular macromolecules. We here report that, in the presence of rapamycin, a potent inhibitor of Target of Rapamycin Complex 1 (TORC1), the fission yeast Schizosaccharomyces pombe can proliferate at high temperatures that usually arrest its growth. Consistently, mutations to the TORC1 subunit RAPTOR/Mip1 and the TORC1 substrate Sck1 significantly improve cellular heat resistance, suggesting that TORC1 restricts fission yeast growth at high temperatures. Aiming for a more comprehensive understanding of the negative regulation of high-temperature growth, we conducted genome-wide screens, which identified additional factors that suppress cell proliferation at high temperatures. Among them is Mks1, which is phosphorylated in a TORC1-dependent manner, forms a complex with the 14-3-3 protein Rad24, and suppresses the high-temperature growth independently of Sck1. Our study has uncovered unexpected mechanisms of growth restraint even below the temperatures deleterious to cell physiology.
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Affiliation(s)
- Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Fontip Mahayot
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Yukiko Nakase
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Jia Xin Soong
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Sayaka Yamawaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Fajar Sofyantoro
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
- Faculty of Biology, Universitas Gadjah Mada, Sleman, Yogyakarta 55281, Indonesia
| | - Yuki Imabata
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Arisa H. Oda
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
| | - Miki Tamura
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
| | - Shunsuke Kofuji
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Yutaka Akikusa
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Ayu Shibatani
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Kunihiro Ohta
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA 95616, USA
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6
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Tai YT, Fukuda T, Morozumi Y, Hirai H, Oda AH, Kamada Y, Akikusa Y, Kanki T, Ohta K, Shiozaki K. Fission Yeast TORC1 Promotes Cell Proliferation through Sfp1, a Transcription Factor Involved in Ribosome Biogenesis. Mol Cell Biol 2023; 43:675-692. [PMID: 38051102 PMCID: PMC10761059 DOI: 10.1080/10985549.2023.2282349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 11/06/2023] [Indexed: 12/07/2023] Open
Abstract
Target of rapamycin complex 1 (TORC1) is activated in response to nutrient availability and growth factors, promoting cellular anabolism and proliferation. To explore the mechanism of TORC1-mediated proliferation control, we performed a genetic screen in fission yeast and identified Sfp1, a zinc-finger transcription factor, as a multicopy suppressor of temperature-sensitive TORC1 mutants. Our observations suggest that TORC1 phosphorylates Sfp1 and protects Sfp1 from proteasomal degradation. Transcription analysis revealed that Sfp1 positively regulates genes involved in ribosome production together with two additional transcription factors, Ifh1/Crf1 and Fhl1. Ifh1 physically interacts with Fhl1, and the nuclear localization of Ifh1 is regulated in response to nutrient levels in a manner dependent on TORC1 and Sfp1. Taken together, our data suggest that the transcriptional regulation of the genes involved in ribosome biosynthesis by Sfp1, Ifh1, and Fhl1 is one of the key pathways through which nutrient-activated TORC1 promotes cell proliferation.
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Affiliation(s)
- Yen Teng Tai
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Tomoyuki Fukuda
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Hayato Hirai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Arisa H. Oda
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Yoshiaki Kamada
- National Institute for Basic Biology, Okazaki, Aichi, Japan
- Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, Japan
| | - Yutaka Akikusa
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Tomotake Kanki
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Kunihiro Ohta
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
- Department of Microbiology and Molecular Genetics, University of California, Davis, California, USA
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7
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Otsubo Y, Yamashita A, Goto Y, Sakai K, Iida T, Yoshimura S, Johzuka K. Cellular responses to compound stress induced by atmospheric-pressure plasma in fission yeast. J Cell Sci 2023; 136:jcs261292. [PMID: 37990810 DOI: 10.1242/jcs.261292] [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: 04/28/2023] [Accepted: 11/13/2023] [Indexed: 11/23/2023] Open
Abstract
The stress response is one of the most fundamental cellular processes. Although the molecular mechanisms underlying responses to a single stressor have been extensively studied, cellular responses to multiple stresses remain largely unknown. Here, we characterized fission yeast cellular responses to a novel stress inducer, non-thermal atmospheric-pressure plasma. Plasma irradiation generates ultraviolet radiation, electromagnetic fields and a variety of chemically reactive species simultaneously, and thus can impose multiple stresses on cells. We applied direct plasma irradiation to fission yeast and showed that strong plasma irradiation inhibited fission yeast growth. We demonstrated that mutants lacking sep1 and ace2, both of which encode transcription factors required for proper cell separation, were resistant to plasma irradiation. Sep1-target transcripts were downregulated by mild plasma irradiation. We also demonstrated that plasma irradiation inhibited the target of rapamycin kinase complex 1 (TORC1). These observations indicate that two pathways, namely the Sep1-Ace2 cell separation pathway and TORC1 pathway, operate when fission yeast cope with multiple stresses induced by plasma irradiation.
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Affiliation(s)
- Yoko Otsubo
- Interdisciplinary Research Unit, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Akira Yamashita
- Interdisciplinary Research Unit, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Center for Low-temperature Plasma Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Yuhei Goto
- Quantitative Biology Research Group, Exploratory Research Center on Life and Living Systems (ExCELLS), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Division of Quantitative Biology, National Institute for Basic Biology, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Keiichiro Sakai
- Quantitative Biology Research Group, Exploratory Research Center on Life and Living Systems (ExCELLS), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Division of Quantitative Biology, National Institute for Basic Biology, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Tetsushi Iida
- Gene Engineering Division, RIKEN BioResource Research Center (BRC), 3-1-1 Koyadai, Tsukuba-shi, Ibaraki 305-0074, Japan
| | - Shinji Yoshimura
- Center for Low-temperature Plasma Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
| | - Katsuki Johzuka
- Interdisciplinary Research Unit, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Astrobiology Center, National Institutes of Natural Sciences, Nishigonaka 38, Myodaiji, Aichi 444-8585, Japan
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8
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Hirai H, Sen Y, Tamura M, Ohta K. TOR inactivation triggers heterochromatin formation in rDNA during glucose starvation. Cell Rep 2023; 42:113320. [PMID: 37913773 DOI: 10.1016/j.celrep.2023.113320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/29/2023] [Accepted: 10/05/2023] [Indexed: 11/03/2023] Open
Abstract
In response to environmental cues, such as nutrient starvation, living organisms modulate gene expression through mechanisms involving histone modifications. Specifically, nutrient depletion inactivates the TOR (target of rapamycin) pathway, leading to reduced expression of ribosomal genes. While these regulatory mechanisms are well elucidated in budding yeast Saccharomyces cerevisiae, their conservation across diverse organisms remains unclear. In this study, we demonstrate that fission yeast Schizosaccharomyces pombe cells repress ribosomal gene transcription through a different mechanism. TORC1, which accumulates in the rDNA region, dissociates upon starvation, resulting in enhanced methylation of H3K9 and heterochromatin formation, facilitated by dissociation of the stress-responsive transcription factor Atf1 and accumulation of the histone chaperone FACT. We propose that this mechanism might be adapted in mammals that possess Suv39H1 and HP1, which are absent in budding yeast.
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Affiliation(s)
- Hayato Hirai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan.
| | - Yuki Sen
- Department of Integrated Sciences, College of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan
| | - Miki Tamura
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan
| | - Kunihiro Ohta
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan; Universal Biology Institute, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
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9
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Ohtsuka H, Otsubo Y, Shimasaki T, Yamashita A, Aiba H. ecl family genes: Factors linking starvation and lifespan extension in Schizosaccharomyces pombe. Mol Microbiol 2023; 120:645-657. [PMID: 37525511 DOI: 10.1111/mmi.15134] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 08/02/2023]
Abstract
In the fission yeast Schizosaccharomyces pombe, the duration of survival in the stationary phase, termed the chronological lifespan (CLS), is affected by various environmental factors and the corresponding gene activities. The ecl family genes were identified in the genomic region encoding non-coding RNA as positive regulators of CLS in S. pombe, and subsequently shown to encode relatively short proteins. Several studies revealed that ecl family genes respond to various nutritional starvation conditions via different mechanisms, and they are additionally involved in stress resistance, autophagy, sexual differentiation, and cell cycle control. Recent studies reported that Ecl family proteins strongly suppress target of rapamycin complex 1, which is a conserved eukaryotic nutrient-sensing kinase complex that also regulates longevity in a variety of organisms. In this review, we introduce the regulatory mechanisms of Ecl family proteins and discuss their emerging findings.
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Affiliation(s)
- Hokuto Ohtsuka
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Yoko Otsubo
- Interdisciplinary Research Unit, National Institute for Basic Biology, Okazaki, Japan
| | - Takafumi Shimasaki
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Akira Yamashita
- Interdisciplinary Research Unit, National Institute for Basic Biology, Okazaki, Japan
| | - Hirofumi Aiba
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
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10
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Acs-Szabo L, Papp LA, Takacs S, Miklos I. Disruption of the Schizosaccharomyces japonicus lig4 Disturbs Several Cellular Processes and Leads to a Pleiotropic Phenotype. J Fungi (Basel) 2023; 9:jof9050550. [PMID: 37233261 DOI: 10.3390/jof9050550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 04/15/2023] [Accepted: 05/05/2023] [Indexed: 05/27/2023] Open
Abstract
Gene targeting is a commonly used method to reveal the function of genes. Although it is an attractive tool for molecular studies, it can frequently be a challenge because its efficiency can be low and it requires the screening of a large number of transformants. Generally, these problems originate from the elevated level of ectopic integration caused by non-homologous DNA end joining (NHEJ). To eliminate this problem, NHEJ-related genes are frequently deleted or disrupted. Although these manipulations can improve gene targeting, the phenotype of the mutant strains raised the question of whether mutations have side effects. The aim of this study was to disrupt the lig4 gene in the dimorphic fission yeast, S. japonicus, and investigate the phenotypic changes of the mutant strain. The mutant cells have shown various phenotypic changes, such as increased sporulation on complete medium, decreased hyphal growth, faster chronological aging, and higher sensitivity to heat shock, UV light, and caffeine. In addition, higher flocculation capacity has been observed, especially at lower sugar concentrations. These changes were supported by transcriptional profiling. Many genes belonging to metabolic and transport processes, cell division, or signaling had altered mRNA levels compared to the control strain. Although the disruption improved the gene targeting, we assume that the lig4 inactivation can cause unexpected physiological side effects, and we have to be very careful with the manipulations of the NHEJ-related genes. To reveal the exact mechanisms behind these changes, further investigations are required.
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Affiliation(s)
- Lajos Acs-Szabo
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Laszlo Attila Papp
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Szonja Takacs
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Ida Miklos
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
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11
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Ohtsuka H, Sakata H, Kitazaki Y, Tada M, Shimasaki T, Otsubo Y, Maekawa Y, Kobayashi M, Imada K, Yamashita A, Aiba H. The ecl family gene ecl3+ is induced by phosphate starvation and contributes to sexual differentiation in fission yeast. J Cell Sci 2023; 136:287015. [PMID: 36779416 PMCID: PMC10038150 DOI: 10.1242/jcs.260759] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/07/2023] [Indexed: 02/14/2023] Open
Abstract
In Schizosaccharomyces pombe, ecl family genes are induced by several signals, such as starvation of various nutrients, including sulfur, amino acids and Mg2+, and environmental stress, including heat or oxidative stress. These genes mediate appropriate cellular responses and contribute to the maintenance of cell viability and induction of sexual differentiation. Although this yeast has three ecl family genes with overlapping functions, any environmental conditions that induce ecl3+ remain unidentified. We demonstrate that ecl3+ is induced by phosphate starvation, similar to its chromosomally neighboring genes, pho1+ and pho84+, which respectively encode an extracellular acid phosphatase and an inorganic phosphate transporter. ecl3+ expression was induced by the transcription factor Pho7 and affected by the cyclin-dependent kinase (CDK)-activating kinase Csk1. Phosphate starvation induced G1 arrest and sexual differentiation via ecl family genes. Biochemical analyses suggested that this G1 arrest was mediated by the stabilization of the CDK inhibitor Rum1, which was dependent on ecl family genes. This study shows that ecl family genes are required for appropriate responses to phosphate starvation and provides novel insights into the diversity and similarity of starvation responses.
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Affiliation(s)
- Hokuto Ohtsuka
- Laboratory of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Hiroki Sakata
- Laboratory of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Yuto Kitazaki
- Laboratory of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Masanobu Tada
- Laboratory of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Takafumi Shimasaki
- Laboratory of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Yoko Otsubo
- Interdisciplinary Research Unit, National Institute for Basic Biology, Okazaki, Aichi 444-858, Japan
- National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
- Center for Novel Science Initiatives, National Institutes of Natural Sciences, Okazaki, Aichi 444-8585, Japan
| | - Yasukichi Maekawa
- Laboratory of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Mikuto Kobayashi
- Laboratory of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Kazuki Imada
- Department of Chemistry and Biochemistry, National Institute of Technology (KOSEN), Suzuka College, Suzuka 510-0294, Japan
- Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Akira Yamashita
- Interdisciplinary Research Unit, National Institute for Basic Biology, Okazaki, Aichi 444-858, Japan
- Center for Low-temperature Plasma Sciences, Nagoya University, Nagoya, Aichi 464-8603, Japan
| | - Hirofumi Aiba
- Laboratory of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
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12
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Alao JP, Legon L, Dabrowska A, Tricolici AM, Kumar J, Rallis C. Interplays of AMPK and TOR in Autophagy Regulation in Yeast. Cells 2023; 12:cells12040519. [PMID: 36831186 PMCID: PMC9953913 DOI: 10.3390/cells12040519] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/08/2023] Open
Abstract
Cells survey their environment and need to balance growth and anabolism with stress programmes and catabolism towards maximum cellular bioenergetics economy and survival. Nutrient-responsive pathways, such as the mechanistic target of rapamycin (mTOR) interact and cross-talk, continuously, with stress-responsive hubs such as the AMP-activated protein kinase (AMPK) to regulate fundamental cellular processes such as transcription, protein translation, lipid and carbohydrate homeostasis. Especially in nutrient stresses or deprivations, cells tune their metabolism accordingly and, crucially, recycle materials through autophagy mechanisms. It has now become apparent that autophagy is pivotal in lifespan, health and cell survival as it is a gatekeeper of clearing damaged macromolecules and organelles and serving as quality assurance mechanism within cells. Autophagy is hard-wired with energy and nutrient levels as well as with damage-response, and yeasts have been instrumental in elucidating such connectivities. In this review, we briefly outline cross-talks and feedback loops that link growth and stress, mainly, in the fission yeast Schizosaccharomyces pombe, a favourite model in cell and molecular biology.
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13
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Comparative Research: Regulatory Mechanisms of Ribosomal Gene Transcription in Saccharomyces cerevisiae and Schizosaccharomyces pombe. Biomolecules 2023; 13:biom13020288. [PMID: 36830657 PMCID: PMC9952952 DOI: 10.3390/biom13020288] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 01/31/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023] Open
Abstract
Restricting ribosome biosynthesis and assembly in response to nutrient starvation is a universal phenomenon that enables cells to survive with limited intracellular resources. When cells experience starvation, nutrient signaling pathways, such as the target of rapamycin (TOR) and protein kinase A (PKA), become quiescent, leading to several transcription factors and histone modification enzymes cooperatively and rapidly repressing ribosomal genes. Fission yeast has factors for heterochromatin formation similar to mammalian cells, such as H3K9 methyltransferase and HP1 protein, which are absent in budding yeast. However, limited studies on heterochromatinization in ribosomal genes have been conducted on fission yeast. Herein, we shed light on and compare the regulatory mechanisms of ribosomal gene transcription in two species with the latest insights.
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14
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Panigrahi L, Anjum S, Ahmed S. Critical role of Wat1/Pop3 in regulating the TORC1 signalling pathway in fission yeast S. pombe. Fungal Genet Biol 2023; 164:103764. [PMID: 36481249 DOI: 10.1016/j.fgb.2022.103764] [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: 08/04/2022] [Revised: 11/21/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
The target of rapamycin (TOR), a major pathway for the regulation of cell growth and proliferation is conserved from yeast to humans. Fission yeast contains two tor complexes, TORC1 is crucial for cell growth while TORC2 gets activated under stress conditions. Pop3/Wat1, a mammalian Lst8 ortholog is an important component of both TOR complexes and has been implicated in the oxidative stress response pathway. Here in this study, the genetic interaction analysis revealed a synthetic lethal interaction of wat1 with tor2-287 mutant cells. Co-immunoprecipitation analysis revealed Wat1 interacts with TORC1 components Tor2, Mip1, and Tco89 while wat1-17 mutant protein fails to interact with these proteins. In the absence of Wat1, the cells arrest at G1 phase with reduced cell size at non-permissive temperature reminiscent of tor2-287 mutant phenotype. Similarly, inactivation of Wat1 results in the failure of TORC1 mediated phosphorylation of Psk1 and Rps602, leading to dysregulation of amino acid permeases and delocalization of Gaf1, a DNA binding transcription factor. Overall, we have hypothesized that Wat1/Pop3 is required to execute the function of TORC1.
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Affiliation(s)
- Lalita Panigrahi
- Biochemistry and Structural Biology Division, CSIR- Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Simmi Anjum
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Shakil Ahmed
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
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15
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Ono Y, Katayama K, Onuma T, Kubo K, Tsuyuzaki H, Hamada M, Sato M. Structure-based screening for functional non-coding RNAs in fission yeast identifies a factor repressing untimely initiation of sexual differentiation. Nucleic Acids Res 2022; 50:11229-11242. [PMID: 36259651 PMCID: PMC9638895 DOI: 10.1093/nar/gkac825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 09/06/2022] [Accepted: 09/14/2022] [Indexed: 12/04/2022] Open
Abstract
Non-coding RNAs (ncRNAs) ubiquitously exist in normal and cancer cells. Despite their prevalent distribution, the functions of most long ncRNAs remain uncharacterized. The fission yeast Schizosaccharomyces pombe expresses >1800 ncRNAs annotated to date, but most unconventional ncRNAs (excluding tRNA, rRNA, snRNA and snoRNA) remain uncharacterized. To discover the functional ncRNAs, here we performed a combinatory screening of computational and biological tests. First, all S. pombe ncRNAs were screened in silico for those showing conservation in sequence as well as in secondary structure with ncRNAs in closely related species. Almost a half of the 151 selected conserved ncRNA genes were uncharacterized. Twelve ncRNA genes that did not overlap with protein-coding sequences were next chosen for biological screening that examines defects in growth or sexual differentiation, as well as sensitivities to drugs and stresses. Finally, we highlighted an ncRNA transcribed from SPNCRNA.1669, which inhibited untimely initiation of sexual differentiation. A domain that was predicted as conserved secondary structure by the computational operations was essential for the ncRNA to function. Thus, this study demonstrates that in silico selection focusing on conservation of the secondary structure over species is a powerful method to pinpoint novel functional ncRNAs.
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Affiliation(s)
- Yu Ono
- Laboratory of Cytoskeletal Logistics, Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Kenta Katayama
- Laboratory of Cytoskeletal Logistics, Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo 162-8480, Japan.,Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), National Institute of Advanced Industrial Science and Technology (AIST), 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Tomoki Onuma
- Laboratory of Cytoskeletal Logistics, Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Kento Kubo
- Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), National Institute of Advanced Industrial Science and Technology (AIST), 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.,Bioinformatics Laboratory, Department of Electrical Engineering and Bioscience, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo Shinjuku-ku, Tokyo 169-8555, Japan
| | - Hayato Tsuyuzaki
- Laboratory of Cytoskeletal Logistics, Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo 162-8480, Japan.,Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), National Institute of Advanced Industrial Science and Technology (AIST), 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
| | - Michiaki Hamada
- Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), National Institute of Advanced Industrial Science and Technology (AIST), 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.,Bioinformatics Laboratory, Department of Electrical Engineering and Bioscience, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo Shinjuku-ku, Tokyo 169-8555, Japan.,Institute for Medical-oriented Structural Biology, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Masamitsu Sato
- Laboratory of Cytoskeletal Logistics, Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo 162-8480, Japan.,Institute for Medical-oriented Structural Biology, Waseda University, 2-2 Wakamatsucho, Shinjuku-ku, Tokyo 162-8480, Japan.,Institute for Advanced Research of Biosystem Dynamics, Waseda Research Institute for Science and Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
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16
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How Metabolic Rate Relates to Cell Size. BIOLOGY 2022; 11:biology11081106. [PMID: 35892962 PMCID: PMC9332559 DOI: 10.3390/biology11081106] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 12/19/2022]
Abstract
Simple Summary The metabolic conversion of resources into living structures and processes is fundamental to all living systems. The rate of metabolism (‘fire of life’) is critical for supporting the rates of various biological processes (‘pace of life’), but why it varies considerably within and among species is little understood. Much of this variation is related to body size, but such ‘metabolic scaling’ relationships also vary extensively. Numerous explanations have been offered, but no consensus has yet been reached. Here, I critically review explanations concerning how cell size and number and their establishment by cell expansion and multiplication may affect metabolic rate and its scaling with body mass. Numerous lines of evidence suggest that cell size and growth can affect metabolic rate at any given body mass, as well as how it changes with increasing body mass during growth or evolution. Mechanisms causing negative associations between cell size and metabolic rate may involve reduced resource supply and/or demand in larger cells, but more research is needed. A cell-size perspective not only helps to explain some (but not all) variation in metabolic rate and its body-mass scaling, but may also foster the conceptual integration of studies of ontogenetic development and body-mass scaling. Abstract Metabolic rate and its covariation with body mass vary substantially within and among species in little understood ways. Here, I critically review explanations (and supporting data) concerning how cell size and number and their establishment by cell expansion and multiplication may affect metabolic rate and its scaling with body mass. Cell size and growth may affect size-specific metabolic rate, as well as the vertical elevation (metabolic level) and slope (exponent) of metabolic scaling relationships. Mechanistic causes of negative correlations between cell size and metabolic rate may involve reduced resource supply and/or demand in larger cells, related to decreased surface area per volume, larger intracellular resource-transport distances, lower metabolic costs of ionic regulation, slower cell multiplication and somatic growth, and larger intracellular deposits of metabolically inert materials in some tissues. A cell-size perspective helps to explain some (but not all) variation in metabolic rate and its body-mass scaling and thus should be included in any multi-mechanistic theory attempting to explain the full diversity of metabolic scaling. A cell-size approach may also help conceptually integrate studies of the biological regulation of cellular growth and metabolism with those concerning major transitions in ontogenetic development and associated shifts in metabolic scaling.
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17
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Stress- and metabolic responses of Candida albicans require Tor1 kinase N-terminal HEAT repeats. PLoS Pathog 2022; 18:e1010089. [PMID: 35687592 PMCID: PMC9223334 DOI: 10.1371/journal.ppat.1010089] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 06/23/2022] [Accepted: 05/12/2022] [Indexed: 11/19/2022] Open
Abstract
Whether to commit limited cellular resources toward growth and proliferation, or toward survival and stress responses, is an essential determination made by Target of Rapamycin Complex 1 (TORC1) for a eukaryotic cell in response to favorable or adverse conditions. Loss of TORC1 function is lethal. The TORC1 inhibitor rapamycin that targets the highly conserved Tor kinase domain kills fungal pathogens like Candida albicans, but is also severely toxic to human cells. The least conserved region of fungal and human Tor kinases are the N-terminal HEAT domains. We examined the role of the 8 most N-terminal HEAT repeats of C. albicans Tor1. We compared nutritional- and stress responses of cells that express a message for N-terminally truncated Tor1 from repressible tetO, with cells expressing wild type TOR1 from tetO or from the native promoter. Some but not all stress responses were significantly impaired by loss of Tor1 N-terminal HEAT repeats, including those to oxidative-, cell wall-, and heat stress; in contrast, plasma membrane stress and antifungal agents that disrupt plasma membrane function were tolerated by cells lacking this Tor1 region. Translation was inappropriately upregulated during oxidative stress in cells lacking N-terminal Tor1 HEAT repeats despite simultaneously elevated Gcn2 activity, while activation of the oxidative stress response MAP kinase Hog1 was weak. Conversely, these cells were unable to take advantage of favorable nutritional conditions by accelerating their growth. Consuming oxygen more slowly than cells containing wild type TOR1 alleles during growth in glucose, cells lacking N-terminal Tor1 HEAT repeats additionally were incapable of utilizing non-fermentable carbon sources. They were also hypersensitive to inhibitors of specific complexes within the respiratory electron transport chain, suggesting that inefficient ATP generation and a resulting dearth of nucleotide sugar building blocks for cell wall polysaccharides causes cell wall integrity defects in these mutants. Genome-wide expression analysis of cells lacking N-terminal HEAT repeats showed dysregulation of carbon metabolism, cell wall biosynthetic enzymes, translational machinery biosynthesis, oxidative stress responses, and hyphal- as well as white-opaque cell type-associated genes. Targeting fungal-specific Tor1 N-terminal HEAT repeats with small molecules might selectively abrogate fungal viability, especially when during infection multiple stresses are imposed by the host immune system. Whether growing harmlessly on our mucous membranes in competition with bacterial multitudes, or invading our tissues and bloodstream, the fungus Candida albicans must be capable of rapid growth when it finds abundant nutrients and favorable conditions. It must also be able to switch to stress- and survival mode when encountering host immune cells and when starving for nutrients. Tor1 kinase is the central regulator at the heart of these cellular decisions. As an essential protein, it is an attractive drug target. But the Tor1 kinase domain is very similar to its human counterpart, rendering its inhibitors like rapamycin toxic for humans. We identified a region of helical protein-protein interaction domains, the N-terminal HEAT repeats, as the least conserved part of C. albicans Tor1. Using genetic- and genome-wide expression analysis, we found that 8 N-terminal HEAT repeats are required for growth acceleration in nutrient-rich environments and for decreased translation in starvation- and stress conditions. This Tor1 region contributes to oxidative-, cell wall- and heat stress reponses, to hyphal growth and to respiration, but apparently not to plasma membrane stress endurance or fermentation. Small molecules that disrupt the protein-protein interactions mediated by this region could become fungal-selective inhibitors of Tor kinase.
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18
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Abstract
Complex multicellular organisms have evolved specific mechanisms to replenish cells in homeostasis and during repair. Here, we discuss how emerging technologies (e.g., single-cell RNA sequencing) challenge the concept that tissue renewal is fueled by unidirectional differentiation from a resident stem cell. We now understand that cell plasticity, i.e., cells adaptively changing differentiation state or identity, is a central tissue renewal mechanism. For example, mature cells can access an evolutionarily conserved program (paligenosis) to reenter the cell cycle and regenerate damaged tissue. Most tissues lack dedicated stem cells and rely on plasticity to regenerate lost cells. Plasticity benefits multicellular organisms, yet it also carries risks. For one, when long-lived cells undergo paligenotic, cyclical proliferation and redif-ferentiation, they can accumulate and propagate acquired mutations that activate oncogenes and increase the potential for developing cancer. Lastly, we propose a new framework for classifying patterns of cell proliferation in homeostasis and regeneration, with stem cells representing just one of the diverse methods that adult tissues employ.
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Affiliation(s)
- Jeffrey W. Brown
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Charles J. Cho
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA,Current affiliation: Section of Gastroenterology and Hepatology, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Jason C. Mills
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA,Current affiliation: Section of Gastroenterology and Hepatology, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA,Departments of Pathology and Immunology and Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA,Current affiliation: Departments of Medicine, Pathology and Immunology, and Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
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19
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Wang T, Woodman P, Humphrey SJ, Petersen J. Environmental control of Pub1 (NEDD4 family E3 ligase) in Schizosaccharomyces pombe is regulated by TORC2 and Gsk3. Life Sci Alliance 2022; 5:5/5/e202101082. [PMID: 35121625 PMCID: PMC8817228 DOI: 10.26508/lsa.202101082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 11/24/2022] Open
Abstract
The NEDD4 family E3 ligase Pub1 is regulated by the nutrient environment, TORC2, and Gsk3 signalling pathway to control the level of amino acid transporters on the plasma membrane and thus nutrient uptake. Cells respond to changing nutrient environments by adjusting the abundance of surface nutrient transporters and receptors. This can be achieved by modulating ubiquitin-dependent endocytosis, which in part is regulated by the NEDD4 family of E3 ligases. Here we report novel regulation of Pub1, a fission yeast Schizosaccharomyces pombe member of the NEDD4-family of E3 ligases. We show that nitrogen stress inhibits Pub1 function, thereby increasing the abundance of the amino acid transporter Aat1 at the plasma membrane and enhancing sensitivity to the toxic arginine analogue canavanine. We show that TOR complex 2 (TORC2) signalling negatively regulates Pub1, thus TORC2 mutants under nutrient stress have decreased Aat1 at the plasma membrane and are resistant to canavanine. Inhibition of TORC2 signalling increases Pub1 phosphorylation, and this is dependent on Gsk3 activity. Addition of the Tor inhibitor Torin1 increases phosphorylation of Pub1 at serine 199 (S199) by 2.5-fold, and Pub1 protein levels in S199A phospho-ablated mutants are reduced. S199 is conserved in NEDD4 and is located immediately upstream of a WW domain required for protein interaction. Together, we describe how the major TORC2 nutrient-sensing signalling network regulates environmental control of Pub1 to modulate the abundance of nutrient transporters.
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Affiliation(s)
- Tingting Wang
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, Australia
| | - Philip Woodman
- School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Sean J Humphrey
- Charles Perkins Centre, School of Life and Environmental Sciences, The University of Sydney, Camperdown, Australia
| | - Janni Petersen
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, Australia
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20
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Cansado J, Soto T, Franco A, Vicente-Soler J, Madrid M. The Fission Yeast Cell Integrity Pathway: A Functional Hub for Cell Survival upon Stress and Beyond. J Fungi (Basel) 2021; 8:jof8010032. [PMID: 35049972 PMCID: PMC8781887 DOI: 10.3390/jof8010032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/27/2021] [Accepted: 12/27/2021] [Indexed: 12/11/2022] Open
Abstract
The survival of eukaryotic organisms during environmental changes is largely dependent on the adaptive responses elicited by signal transduction cascades, including those regulated by the Mitogen-Activated Protein Kinase (MAPK) pathways. The Cell Integrity Pathway (CIP), one of the three MAPK pathways found in the simple eukaryote fission of yeast Schizosaccharomyces pombe, shows strong homology with mammalian Extracellular signal-Regulated Kinases (ERKs). Remarkably, studies over the last few decades have gradually positioned the CIP as a multi-faceted pathway that impacts multiple functional aspects of the fission yeast life cycle during unperturbed growth and in response to stress. They include the control of mRNA-stability through RNA binding proteins, regulation of calcium homeostasis, and modulation of cell wall integrity and cytokinesis. Moreover, distinct evidence has disclosed the existence of sophisticated interplay between the CIP and other environmentally regulated pathways, including Stress-Activated MAP Kinase signaling (SAPK) and the Target of Rapamycin (TOR). In this review we present a current overview of the organization and underlying regulatory mechanisms of the CIP in S. pombe, describe its most prominent functions, and discuss possible targets of and roles for this pathway. The evolutionary conservation of CIP signaling in the dimorphic fission yeast S. japonicus will also be addressed.
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21
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Calvo IA, Sharma S, Paulo JA, Gulka AO, Boeszoermenyi A, Zhang J, Lombana JM, Palmieri CM, Laviolette LA, Arthanari H, Iliopoulos O, Gygi SP, Motamedi M. The fission yeast FLCN/FNIP complex augments TORC1 repression or activation in response to amino acid (AA) availability. iScience 2021; 24:103338. [PMID: 34805795 PMCID: PMC8590082 DOI: 10.1016/j.isci.2021.103338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/10/2021] [Accepted: 10/21/2021] [Indexed: 11/13/2022] Open
Abstract
The target of Rapamycin complex1 (TORC1) senses and integrates several environmental signals, including amino acid (AA) availability, to regulate cell growth. Folliculin (FLCN) is a tumor suppressor (TS) protein in renal cell carcinoma, which paradoxically activates TORC1 in response to AA supplementation. Few tractable systems for modeling FLCN as a TS are available. Here, we characterize the FLCN-containing complex in Schizosaccharomyces pombe (called BFC) and show that BFC augments TORC1 repression and activation in response to AA starvation and supplementation, respectively. BFC co-immunoprecipitates V-ATPase, a TORC1 modulator, and regulates its activity in an AA-dependent manner. BFC genetic and proteomic networks identify the conserved peptide transmembrane transporter Ptr2 and the phosphoribosylformylglycinamidine synthase Ade3 as new AA-dependent regulators of TORC1. Overall, these data ascribe an additional repressive function to Folliculin in TORC1 regulation and reveal S. pombe as an excellent system for modeling the AA-dependent, FLCN-mediated repression of TORC1 in eukaryotes.
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Affiliation(s)
- Isabel A. Calvo
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Shalini Sharma
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Joao A. Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Alexander O.D. Gulka
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Andras Boeszoermenyi
- Department of Biochemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Jingyu Zhang
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Jose M. Lombana
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Christina M. Palmieri
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Laura A. Laviolette
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Haribabu Arthanari
- Department of Biochemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Othon Iliopoulos
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
- Division of Hematology-Oncology, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Steven P. Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Mo Motamedi
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
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22
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Toullec D, Elías-Villalobos A, Faux C, Noly A, Lledo G, Séveno M, Helmlinger D. The Hsp90 cochaperone TTT promotes cotranslational maturation of PIKKs prior to complex assembly. Cell Rep 2021; 37:109867. [PMID: 34686329 DOI: 10.1016/j.celrep.2021.109867] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 07/30/2021] [Accepted: 09/30/2021] [Indexed: 01/28/2023] Open
Abstract
Phosphatidylinositol 3-kinase-related kinases (PIKKs) are a family of kinases that control fundamental processes, including cell growth, DNA damage repair, and gene expression. Although their regulation and activities are well characterized, little is known about how PIKKs fold and assemble into active complexes. Previous work has identified a heat shock protein 90 (Hsp90) cochaperone, the TTT complex, that specifically stabilizes PIKKs. Here, we describe a mechanism by which TTT promotes their de novo maturation in fission yeast. We show that TTT recognizes newly synthesized PIKKs during translation. Although PIKKs form multimeric complexes, we find that they do not engage in cotranslational assembly with their partners. Rather, our findings suggest a model by which TTT protects nascent PIKK polypeptides from misfolding and degradation because PIKKs acquire their native state after translation is terminated. Thus, PIKK maturation and assembly are temporally segregated, suggesting that the biogenesis of large complexes requires both dedicated chaperones and cotranslational interactions between subunits.
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Affiliation(s)
- Damien Toullec
- CRBM, University of Montpellier, CNRS, Montpellier, France
| | | | - Céline Faux
- CRBM, University of Montpellier, CNRS, Montpellier, France
| | - Ambre Noly
- CRBM, University of Montpellier, CNRS, Montpellier, France
| | | | - Martial Séveno
- BioCampus Montpellier, University of Montpellier, CNRS, INSERM, Montpellier, France
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23
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Morozumi Y, Hishinuma A, Furusawa S, Sofyantoro F, Tatebe H, Shiozaki K. Fission yeast TOR complex 1 phosphorylates Psk1 through an evolutionarily conserved interaction mediated by the TOS motif. J Cell Sci 2021; 134:272450. [PMID: 34499159 PMCID: PMC8542387 DOI: 10.1242/jcs.258865] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 09/03/2021] [Indexed: 12/28/2022] Open
Abstract
TOR complex 1 (TORC1) is a multi-subunit protein kinase complex that controls cellular growth in response to environmental cues. The regulatory subunits of mammalian TORC1 (mTORC1) include RAPTOR (also known as RPTOR), which recruits mTORC1 substrates, such as S6K1 (also known as RPS6KB1) and 4EBP1 (EIF4EBP1), by interacting with their TOR signaling (TOS) motif. Despite the evolutionary conservation of TORC1, no TOS motif has been described in lower eukaryotes. In the present study, we show that the fission yeast S6 kinase Psk1 contains a TOS motif that interacts with Mip1, a RAPTOR ortholog. The TOS motif in Psk1 resembles those in mammals, including the conserved phenylalanine and aspartic acid residues essential for the Mip1 interaction and TORC1-dependent phosphorylation of Psk1. The binding of the TOS motif to Mip1 is dependent on Mip1 Tyr-533, whose equivalent in RAPTOR is known to interact with the TOS motif in their co-crystals. Furthermore, we utilized the mip1-Y533A mutation to screen the known TORC1 substrates in fission yeast and successfully identified Atg13 as a novel TOS-motif-containing substrate. These results strongly suggest that the TOS motif represents an evolutionarily conserved mechanism of the substrate recognition by TORC1. Summary: By analyzing S6 kinase in fission yeast, we have demonstrated that the TOR signaling (TOS) motif-mediated substrate recognition by TOR complex 1 is conserved from yeast to humans.
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Affiliation(s)
- Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Ai Hishinuma
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.,Tohoku Agricultural Research Center, National Agriculture and Food Research Organization, Daisen, Akita 019-2112, Japan
| | - Suguru Furusawa
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Fajar Sofyantoro
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.,Department of Animal Physiology, Faculty of Biology, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia
| | - Hisashi Tatebe
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.,Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA
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24
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Navratilova A, Kovar M, Trakovicka A, Pozgajova M. Nickel induced cell impairments are negatively regulated by the Tor1 kinase in Schizosaccharomyces pombe. World J Microbiol Biotechnol 2021; 37:165. [PMID: 34458935 DOI: 10.1007/s11274-021-03130-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 08/17/2021] [Indexed: 11/26/2022]
Abstract
In our study we investigated the effect of different nickel (NiSO4·6H2O) (Ni) concentrations on cell division, cellular morphology and ionome homeostasis of the eukaryotic model organism Schizosaccharomyces pombe. Target of rapamycin (TOR) protein kinase is one of the key regulators of cell growth under different environmental stresses. We analyzed the effect of Ni on cell strains lacking the Tor1 signaling pathway utilizing light-absorbance spectroscopy, visualization, microscopy and inductively coupled plasma optical emission spectroscopy. Interestingly, our findings revealed that Ni mediated cell growth alterations are noticeably lower in Tor1 deficient cells. Greater size of Tor1 depleted cells reached similar quantitative parameters to wild type cells upon incubation with 400 μM Ni. Differences of ion levels among the two tested yeast strains were detected even before Ni addition. Addition of high concentration (1 mM) of the heavy metal, representing acute contamination, caused considerable changes in the ionome of both strains. Strikingly, Tor1 deficient cells displayed largely reduced Ni content after treatment compared to wild type controls (644.1 ± 49 vs. 2096.8 ± 75 μg/g), suggesting its significant role in Ni trafficking. Together our results predict yet undefined role for the Tor1 signaling in metal uptake and/or metabolism.
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Affiliation(s)
- Alica Navratilova
- Department of Genetics and Breeding Biology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94976, Nitra, Slovakia
| | - Marek Kovar
- Department of Plant Physiology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94976, Nitra, Slovakia
| | - Anna Trakovicka
- Department of Genetics and Breeding Biology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94976, Nitra, Slovakia
| | - Miroslava Pozgajova
- AgroBioTech Research Centre, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94976, Nitra, Slovakia.
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25
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Corral-Ramos C, Barrios R, Ayté J, Hidalgo E. TOR and MAP kinase pathways synergistically regulate autophagy in response to nutrient depletion in fission yeast. Autophagy 2021; 18:375-390. [PMID: 34157946 DOI: 10.1080/15548627.2021.1935522] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
General autophagy is an evolutionarily conserved process in eukaryotes, by which intracellular materials are transported into and degraded inside lysosomes or vacuoles, with the main goal of recycling those materials during periods of starvation. The molecular bases of autophagy have been widely described in Saccharomyces cerevisiae, and the specific roles of Atg proteins in the process were first characterized in this model system. Important contributions have been made in Schizosaccharomyces pombe highlighting the evolutionary similarity and, at the same time, diversity of Atg components in autophagy. However, little is known regarding signals, pathways and role of autophagy in this distant yeast. Here, we undertake a global approach to investigate the signals, the pathways and the consequences of autophagy activation. We demonstrate that not only nitrogen but several nutritional deprivations including lack of carbon, sulfur, phosphorus or leucine sources, trigger autophagy, and that the TORC1, TORC2 and MAP kinase Sty1 pathways control the onset of autophagy. Furthermore, we identify an unexpected phenotype of autophagy-defective mutants, namely their inability to survive in the absence of leucine when biosynthesis of this amino acid is impaired.Abbreviations: ATG: autophagy-related; cAMP: cyclic adenosine monophosphate; cDNA: complementary deoxyribonucleic acid; GFP: green fluorescence protein; Gluc: glucose; Leu: leucine; MAP: mitogen-activated protein; MM: minimal medium; PI: propidium iodine; PKA: protein kinase A; RNA: ribonucleic acid; RT-qPCR: real time quantitative polymerase chain reaction; S. cerevisiae: Saccharomyces cerevisiae; S. pombe: Schizosaccharomyces pombe; TCA: trichloroacetic acid; TOR: target of rapamycin; TORC1: target of rapamycin complex 1; TORC2: target of rapamycin complex 2; YE5S: yeast extract 5 amino acid supplemented.
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Affiliation(s)
| | - Rubén Barrios
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
| | - Elena Hidalgo
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
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26
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Inamura SI, Tanabe T, Kawamukai M, Matsuo Y. Expression of Mug14 is regulated by the transcription factor Rst2 through the cAMP-dependent protein kinase pathway in Schizosaccharomyces pombe. Curr Genet 2021; 67:807-821. [PMID: 34086083 DOI: 10.1007/s00294-021-01194-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/26/2021] [Accepted: 05/28/2021] [Indexed: 01/04/2023]
Abstract
The cAMP-dependent protein kinase (Pka1) regulates many cellular events, including sexual development and glycogenesis, and response to the limitation of glucose, in Schizosaccharomyces pombe. Despite its importance in many cellular events, the targets of the cAMP/PKA pathway have not been fully investigated. Here, we demonstrate that the expression of mug14 is induced by downregulation of the cAMP/PKA pathway and limitation of glucose. This regulation is dependent on the function of Rst2, a transcription factor that regulates transition from mitosis to meiosis. The loss of the C2H2-type zinc finger domain in Rst2, termed Rst2 (C2H2∆), abolished the induction of Mug14 expression. Upon deletion of the stress starvation response element of the S. pombe (STREP: CCCCTC) sequence, which is a potential binding site of Rst2 on mug14, in the pka1∆ strain, its induction was abolished. The expression of Mug14 was significantly reduced and delayed by the limitation of glucose and also by nitrogen starvation in the rst2∆ strain. Mug14 is known to share a common function with Mde1 and Mta3 in the methionine salvage pathway, but the expression of mde1 and mta3 mRNAs was not enhanced by pka1 deletion and limitation of glucose. We conclude that the expression of Mug14 is upregulated by Rst2 under the control of the cAMP/PKA signaling pathway, which senses the limitation of glucose.
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Affiliation(s)
- Shin-Ich Inamura
- Graduate School of Natural Science and Technology, Shimane University, Matsue, 690-8504, Japan
| | - Takuma Tanabe
- Department of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, Matsue, 690-8504, Japan
| | - Makoto Kawamukai
- Graduate School of Natural Science and Technology, Shimane University, Matsue, 690-8504, Japan.,Department of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, Matsue, 690-8504, Japan.,Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, 690-8504, Japan
| | - Yasuhiro Matsuo
- Graduate School of Natural Science and Technology, Shimane University, Matsue, 690-8504, Japan. .,Department of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, Matsue, 690-8504, Japan. .,Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, 690-8504, Japan.
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27
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Halova L, Cobley D, Franz-Wachtel M, Wang T, Morrison KR, Krug K, Nalpas N, Maček B, Hagan IM, Humphrey SJ, Petersen J. A TOR (target of rapamycin) and nutritional phosphoproteome of fission yeast reveals novel targets in networks conserved in humans. Open Biol 2021; 11:200405. [PMID: 33823663 PMCID: PMC8025308 DOI: 10.1098/rsob.200405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/05/2021] [Indexed: 12/21/2022] Open
Abstract
Fluctuations in TOR, AMPK and MAP-kinase signalling maintain cellular homeostasis and coordinate growth and division with environmental context. We have applied quantitative, SILAC mass spectrometry to map TOR and nutrient-controlled signalling in the fission yeast Schizosaccharomyces pombe. Phosphorylation levels at more than 1000 sites were altered following nitrogen stress or Torin1 inhibition of the TORC1 and TORC2 networks that comprise TOR signalling. One hundred and thirty of these sites were regulated by both perturbations, and the majority of these (119) new targets have not previously been linked to either nutritional or TOR control in either yeasts or humans. Elimination of AMPK inhibition of TORC1, by removal of AMPKα (ssp2::ura4+), identified phosphosites where nitrogen stress-induced changes were independent of TOR control. Using a yeast strain with an ATP analogue-sensitized Cdc2 kinase, we excluded sites that were changed as an indirect consequence of mitotic control modulation by nitrogen stress or TOR signalling. Nutritional control of gene expression was reflected in multiple targets in RNA metabolism, while significant modulation of actin cytoskeletal components points to adaptations in morphogenesis and cell integrity networks. Reduced phosphorylation of the MAPKK Byr1, at a site whose human equivalent controls docking between MEK and ERK, prevented sexual differentiation when resources were sparse but not eliminated.
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Affiliation(s)
- Lenka Halova
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
- Cancer Research UK Manchester Institute, Alderley Park, Macclesfield SK10 4TG, UK
| | - David Cobley
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Mirita Franz-Wachtel
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Tingting Wang
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia 5042, Australia
| | - Kaitlin R. Morrison
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia 5042, Australia
| | - Karsten Krug
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Nicolas Nalpas
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Boris Maček
- Proteome Center Tuebingen, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Iain M. Hagan
- Cancer Research UK Manchester Institute, Alderley Park, Macclesfield SK10 4TG, UK
| | - Sean J. Humphrey
- Charles Perkins Centre, School of Life and Environmental Sciences, The University of Sydney, Camperdown, New South Wales, Australia
| | - Janni Petersen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia 5042, Australia
- Nutrition and Metabolism, South Australia Health and Medical Research Institute, North Terrace, Adelaide, South Australia 5000, Australia
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28
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Barve G, Manjithaya R. Cross-talk between autophagy and sporulation in Saccharomyces cerevisiae. Yeast 2021; 38:401-413. [PMID: 33608896 DOI: 10.1002/yea.3556] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 01/25/2021] [Accepted: 02/12/2021] [Indexed: 11/10/2022] Open
Abstract
Unicellular organisms, like yeast, have developed mechanisms to overcome environmental stress conditions like nutrient starvation. Autophagy and sporulation are two such mechanisms employed by yeast cells. Autophagy is a well-conserved, catabolic process that degrades excess and unwanted cytoplasmic materials and provides building blocks during starvation conditions. Thus, autophagy maintains cellular homeostasis at basal conditions and acts as a survival mechanism during stress conditions. Sporulation is an essential process that, like autophagy, is triggered due to stress conditions in yeast. It involves the formation of ascospores that protect the yeast cells during extreme conditions and germinate when the conditions are favorable. Studies show that autophagy is required for the sporulation process in yeast. However, the exact mechanism of action is not clear. Furthermore, several of the core autophagy gene knockouts do not sporulate and at what stage of sporulation they are involved is not clear. Besides, many overlapping proteins function in both sporulation and autophagy and it is unclear how the pathway-specific roles of these proteins are determined. All these observations suggest that the two processes cross-talk. Individually, some key features from both the processes remain to be studied with respect to the source of membrane for autophagosomes, prospore membrane (PSM) formation, and closure of the membranes. Therefore, it becomes crucial to study the cross-talk between autophagy and sporulation. In this review, the cross-talk between the two pathways, the common protein machineries have been discussed.
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Affiliation(s)
- Gaurav Barve
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India
| | - Ravi Manjithaya
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India
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29
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TOR targets an RNA processing network to regulate facultative heterochromatin, developmental gene expression and cell proliferation. Nat Cell Biol 2021; 23:243-256. [PMID: 33574613 PMCID: PMC9260697 DOI: 10.1038/s41556-021-00631-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 01/06/2021] [Indexed: 01/30/2023]
Abstract
Cell proliferation and differentiation require signalling pathways that enforce appropriate and timely gene expression. We find that Tor2, the catalytic subunit of the TORC1 complex in fission yeast, targets a conserved nuclear RNA elimination network, particularly the serine and proline-rich protein Pir1, to control gene expression through RNA decay and facultative heterochromatin assembly. Phosphorylation by Tor2 protects Pir1 from degradation by the ubiquitin-proteasome system involving the polyubiquitin Ubi4 stress-response protein and the Cul4-Ddb1 E3 ligase. This pathway suppresses widespread and untimely gene expression and is critical for sustaining cell proliferation. Moreover, we find that the dynamic nature of Tor2-mediated control of RNA elimination machinery defines gene expression patterns that coordinate fundamental chromosomal events during gametogenesis, such as meiotic double-strand-break formation and chromosome segregation. These findings have important implications for understanding how the TOR signalling pathway reprogrammes gene expression patterns and contributes to diseases such as cancer.
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30
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Andric V, Nevers A, Hazra D, Auxilien S, Menant A, Graille M, Palancade B, Rougemaille M. A scaffold lncRNA shapes the mitosis to meiosis switch. Nat Commun 2021; 12:770. [PMID: 33536434 PMCID: PMC7859202 DOI: 10.1038/s41467-021-21032-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 01/05/2021] [Indexed: 11/09/2022] Open
Abstract
Long non-coding RNAs (lncRNAs) contribute to the regulation of gene expression in response to intra- or extracellular signals but the underlying molecular mechanisms remain largely unexplored. Here, we identify an uncharacterized lncRNA as a central player in shaping the meiotic gene expression program in fission yeast. We report that this regulatory RNA, termed mamRNA, scaffolds the antagonistic RNA-binding proteins Mmi1 and Mei2 to ensure their reciprocal inhibition and fine tune meiotic mRNA degradation during mitotic growth. Mechanistically, mamRNA allows Mmi1 to target Mei2 for ubiquitin-mediated downregulation, and conversely enables accumulating Mei2 to impede Mmi1 activity, thereby reinforcing the mitosis to meiosis switch. These regulations also occur within a unique Mmi1-containing nuclear body, positioning mamRNA as a spatially-confined sensor of Mei2 levels. Our results thus provide a mechanistic basis for the mutual control of gametogenesis effectors and further expand our vision of the regulatory potential of lncRNAs.
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Affiliation(s)
- Vedrana Andric
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Alicia Nevers
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
- University Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
| | - Ditipriya Hazra
- Laboratoire de Biologie Structurale de la Cellule (BIOC), CNRS, Ecole polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau, France
- Department of Biochemistry, Oxford University, Oxford, OX1 3QU, UK
| | - Sylvie Auxilien
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Alexandra Menant
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Marc Graille
- Laboratoire de Biologie Structurale de la Cellule (BIOC), CNRS, Ecole polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau, France
| | - Benoit Palancade
- Université de Paris, CNRS, Institut Jacques Monod, F-75006, Paris, France
| | - Mathieu Rougemaille
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
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31
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Morozumi Y, Shiozaki K. Conserved and Divergent Mechanisms That Control TORC1 in Yeasts and Mammals. Genes (Basel) 2021; 12:genes12010088. [PMID: 33445779 PMCID: PMC7828246 DOI: 10.3390/genes12010088] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/10/2021] [Accepted: 01/11/2021] [Indexed: 12/23/2022] Open
Abstract
Target of rapamycin complex 1 (TORC1), a serine/threonine-protein kinase complex highly conserved among eukaryotes, coordinates cellular growth and metabolism with environmental cues, including nutrients and growth factors. Aberrant TORC1 signaling is associated with cancers and various human diseases, and TORC1 also plays a key role in ageing and lifespan, urging current active research on the mechanisms of TORC1 regulation in a variety of model organisms. Identification and characterization of the RAG small GTPases as well as their regulators, many of which are highly conserved from yeast to humans, led to a series of breakthroughs in understanding the molecular bases of TORC1 regulation. Recruitment of mammalian TORC1 (mTORC1) by RAGs to lysosomal membranes is a key step for mTORC1 activation. Interestingly, the RAG GTPases in fission yeast are primarily responsible for attenuation of TORC1 activity on vacuoles, the yeast equivalent of lysosomes. In this review, we summarize our current knowledge about the functions of TORC1 regulators on yeast vacuoles, and illustrate the conserved and divergent mechanisms of TORC1 regulation between yeasts and mammals.
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Affiliation(s)
- Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan;
- Correspondence: ; Tel.: +81-743-72-5543
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan;
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA
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32
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Otsubo Y, Kamada Y, Yamashita A. Novel Links between TORC1 and Traditional Non-Coding RNA, tRNA. Genes (Basel) 2020; 11:E956. [PMID: 32825021 PMCID: PMC7563549 DOI: 10.3390/genes11090956] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/17/2020] [Accepted: 08/17/2020] [Indexed: 12/19/2022] Open
Abstract
Target of rapamycin (TOR) is a serine/threonine kinase that modulates cell growth and metabolism in response to environmental changes. Transfer RNA (tRNA) is an abundant and ubiquitous small non-coding RNA that is essential in the translation of mRNAs. Beyond its canonical role, it has been revealed that tRNAs have more diverse functions. TOR complex 1 (TORC1), which is one of the two TOR complexes, regulates tRNA synthesis by controlling RNA polymerase III. In addition to tRNA synthesis regulation, recent studies have revealed hidden connections between TORC1 and tRNA, which are both essential players in eukaryotic cellular activities. Here, we review the accumulating findings on the regulatory links between TORC1 and tRNA-particularly those links in the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe.
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Affiliation(s)
- Yoko Otsubo
- National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan; (Y.O.); (Y.K.)
- National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
- Center for Novel Science Initiatives, National Institutes of Natural Sciences, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Yoshiaki Kamada
- National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan; (Y.O.); (Y.K.)
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Akira Yamashita
- National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan; (Y.O.); (Y.K.)
- Center for Novel Science Initiatives, National Institutes of Natural Sciences, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
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33
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Ling NXY, Kaczmarek A, Hoque A, Davie E, Ngoei KRW, Morrison KR, Smiles WJ, Forte GM, Wang T, Lie S, Dite TA, Langendorf CG, Scott JW, Oakhill JS, Petersen J. mTORC1 directly inhibits AMPK to promote cell proliferation under nutrient stress. Nat Metab 2020; 2:41-49. [PMID: 31993556 PMCID: PMC6986917 DOI: 10.1038/s42255-019-0157-1] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 12/10/2019] [Indexed: 11/20/2022]
Abstract
Central to cellular metabolism and cell proliferation are highly conserved signalling pathways controlled by mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK)1,2, dysregulation of which are implicated in pathogenesis of major human diseases such as cancer and type 2 diabetes. AMPK pathways leading to reduced cell proliferation are well established and, in part, act through inhibition of TOR complex-1 (TORC1) activity. Here we demonstrate reciprocal regulation, specifically that TORC1 directly down-regulates AMPK signalling by phosphorylating the evolutionarily conserved residue Ser367 in the fission yeast AMPK catalytic subunit Ssp2, and AMPK α1Ser347/α2Ser345 in the mammalian homologs, which is associated with reduced phosphorylation of activation loop Thr172. Genetic or pharmacological inhibition of TORC1 signalling led to AMPK activation in the absence of increased AMP:ATP ratios; under nutrient stress conditions this was associated with growth limitation in both yeast and human cell cultures. Our findings reveal fundamental, bi-directional regulation between two major metabolic signalling networks and uncover new opportunity for cancer treatment strategies aimed at suppressing cell proliferation in the nutrient-poor tumor microenvironment.
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Affiliation(s)
- Naomi X Y Ling
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Adrian Kaczmarek
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Ashfaqul Hoque
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Elizabeth Davie
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Kevin R W Ngoei
- Protein Chemistry and Metabolism Unit, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Kaitlin R Morrison
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - William J Smiles
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | | | - Tingting Wang
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Shervi Lie
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Toby A Dite
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
- MRC Protein Phosphorylation and Ubiquitylation Unit, James Black Centre, University of Dundee, Dundee, UK
| | - Christopher G Langendorf
- Protein Chemistry and Metabolism Unit, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - John W Scott
- Protein Chemistry and Metabolism Unit, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia
- Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Jonathan S Oakhill
- Metabolic Signalling Laboratory, St Vincent's Institute of Medical Research, School of Medicine, University of Melbourne, Melbourne, Victoria, Australia.
- Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia.
| | - Janni Petersen
- Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.
- Faculty of Life Sciences, University of Manchester, Manchester, UK.
- Nutrition and Metabolism, South Australia Health and Medical Research Institute, Adelaide, South Australia, Australia.
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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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Reidman S, Cohen A, Kupiec M, Weisman R. The cytosolic form of aspartate aminotransferase is required for full activation of TOR complex 1 in fission yeast. J Biol Chem 2019; 294:18244-18255. [PMID: 31641022 DOI: 10.1074/jbc.ra119.010101] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 10/18/2019] [Indexed: 12/17/2022] Open
Abstract
The evolutionarily conserved TOR complex 1 (TORC1) activates cell growth and proliferation in response to nutritional signals. In the fission yeast Schizosaccharomyces pombe, TORC1 is essential for vegetative growth, and its activity is regulated in response to nitrogen quantity and quality. Yet, how TORC1 senses nitrogen is poorly understood. Rapamycin, a specific TOR inhibitor, inhibits growth in S. pombe only under conditions in which the activity of TORC1 is compromised. In a genetic screen for rapamycin-sensitive mutations, we isolated caa1-1, a loss-of-function mutation of the cytosolic form of aspartate aminotransferase (Caa1). We demonstrate that loss of caa1 + partially mimics loss of TORC1 activity and that Caa1 is required for full TORC1 activity. Disruption of caa1 + resulted in aspartate auxotrophy, a finding that prompted us to assess the role of aspartate in TORC1 activation. We found that the amino acids glutamine, asparagine, arginine, aspartate, and serine activate TORC1 most efficiently following nitrogen starvation. The glutamine synthetase inhibitor l-methionine sulfoximine abolished the ability of asparagine, arginine, aspartate, or serine, but not that of glutamine, to induce TORC1 activity, consistent with a central role for glutamine in activating TORC1. Neither addition of aspartate nor addition of glutamine restored TORC1 activity in caa1-deleted cells or in cells carrying a Caa1 variant with a catalytic site substitution, suggesting that the catalytic activity of Caa1 is required for TORC1 activation. Taken together, our results reveal the contribution of the key metabolic enzyme Caa1 to TORC1 activity in S. pombe.
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Affiliation(s)
- Sophie Reidman
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Adiel Cohen
- Department of Natural and Life Sciences, the Open University of Israel, University Road 1, 4353701 Ra'anana, Israel
| | - Martin Kupiec
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Ronit Weisman
- Department of Natural and Life Sciences, the Open University of Israel, University Road 1, 4353701 Ra'anana, Israel.
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36
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Andreadis C, Hulme L, Wensley K, Liu JL. The TOR pathway modulates cytoophidium formation in Schizosaccharomyces pombe. J Biol Chem 2019; 294:14686-14703. [PMID: 31431504 PMCID: PMC6779450 DOI: 10.1074/jbc.ra119.009913] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 08/09/2019] [Indexed: 12/30/2022] Open
Abstract
CTP synthase (CTPS) has been demonstrated to form evolutionarily-conserved filamentous structures termed cytoophidia whose exact cellular functions remain unclear, but they may play a role in intracellular compartmentalization. We have previously shown that the mammalian target of rapamycin complex 1 (mTORC1)-S6K1 pathway mediates cytoophidium assembly in mammalian cells. Here, using the fission yeast Schizosaccharomyces pombe as a model of a unicellular eukaryote, we demonstrate that the target of rapamycin (TOR)-signaling pathway regulates cytoophidium formation (from the S. pombe CTPS ortholog Cts1) also in S. pombe Conducting a systematic analysis of all viable single TOR subunit-knockout mutants and of several major downstream effector proteins, we found that Cts1 cytoophidia are significantly shortened and often dissociate when TOR is defective. We also found that the activities of the downstream effector kinases of the TORC1 pathway, Sck1, Sck2, and Psk1 S6, as well as of the S6K/AGC kinase Gad8, the major downstream effector kinase of the TORC2 pathway, are necessary for proper cytoophidium filament formation. Interestingly, we observed that the Crf1 transcriptional corepressor for ribosomal genes is a strong effector of Cts1 filamentation. Our findings connect TOR signaling, a major pathway required for cell growth, with the compartmentalization of the essential nucleotide synthesis enzyme CTPS, and we uncover differences in the regulation of its filamentation among higher multicellular and unicellular eukaryotic systems.
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Affiliation(s)
- Christos Andreadis
- School of Life Sciences and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Lydia Hulme
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Katherine Wensley
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Ji-Long Liu
- School of Life Sciences and Technology, ShanghaiTech University, 201210 Shanghai, China .,MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
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Candiracci J, Migeot V, Chionh YH, Bauer F, Brochier T, Russell B, Shiozaki K, Dedon P, Hermand D. Reciprocal regulation of TORC signaling and tRNA modifications by Elongator enforces nutrient-dependent cell fate. SCIENCE ADVANCES 2019; 5:eaav0184. [PMID: 31223645 PMCID: PMC6584457 DOI: 10.1126/sciadv.aav0184] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 05/14/2019] [Indexed: 06/09/2023]
Abstract
Nutrient availability has a profound impact on cell fate. Upon nitrogen starvation, wild-type fission yeast cells uncouple cell growth from cell division to generate small, round-shaped cells that are competent for sexual differentiation. The TORC1 (TOR complex 1) and TORC2 complexes exert opposite controls on cell growth and cell differentiation, but little is known about how their activity is coordinated. We show that transfer RNA (tRNA) modifications by Elongator are critical for this regulation by promoting the translation of both key components of TORC2 and repressors of TORC1. We further identified the TORC2 pathway as an activator of Elongator by down-regulating a Gsk3 (glycogen synthase kinase 3)-dependent inhibitory phosphorylation of Elongator. Therefore, a feedback control is operating between TOR complex (TORC) signaling and tRNA modification by Elongator to enforce the advancement of mitosis that precedes cell differentiation.
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Affiliation(s)
- Julie Candiracci
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Valerie Migeot
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Yok-Hian Chionh
- Singapore–MIT Alliance for Research and Technology Centre (SMART), Center for Life Sciences 05-06, 28 Medical Drive, 117456 Singapore
| | - Fanelie Bauer
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Thomas Brochier
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
| | - Brandon Russell
- Massachusetts Institute of Technology, 56-787B77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA
| | - Peter Dedon
- Singapore–MIT Alliance for Research and Technology Centre (SMART), Center for Life Sciences 05-06, 28 Medical Drive, 117456 Singapore
- Massachusetts Institute of Technology, 56-787B77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
| | - Damien Hermand
- URPHYM-GEMO, University of Namur, rue de Bruxelles, 61, Namur 5000, Belgium
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38
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Lie S, Banks P, Lawless C, Lydall D, Petersen J. The contribution of non-essential Schizosaccharomyces pombe genes to fitness in response to altered nutrient supply and target of rapamycin activity. Open Biol 2019; 8:rsob.180015. [PMID: 29720420 PMCID: PMC5990653 DOI: 10.1098/rsob.180015] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 04/06/2018] [Indexed: 12/12/2022] Open
Abstract
Nutrient fluctuations in the cellular environment promote changes in cell metabolism and growth to adapt cell proliferation accordingly. The target of rapamycin (TOR) signalling network plays a key role in the coordination of growth and cell proliferation with the nutrient environment and, importantly, nutrient limitation reduces TOR complex 1 (TORC1) signalling. We have performed global quantitative fitness profiling of the collection of Schizosaccharomyces pombe strains from which non-essential genes have been deleted. We identified genes that regulate fitness when cells are grown in a nutrient-rich environment compared with minimal environments, with varying nitrogen sources including ammonium, glutamate and proline. In addition, we have performed the first global screen for genes that regulate fitness when both TORC1 and TORC2 signalling is reduced by Torin1. Analysis of genes whose deletions altered fitness when nutrients were limited, or when TOR signalling was compromised, identified a large number of genes that regulate transmembrane transport, transcription and chromatin organization/regulation and vesicle-mediated transport. The ability to tolerate reduced TOR signalling placed demands upon a large number of biological processes including autophagy, mRNA metabolic processing and nucleocytoplasmic transport. Importantly, novel biological processes and all processes known to be regulated by TOR were identified in our screens. In addition, deletion of 62 genes conserved in humans gave rise to strong sensitivity or resistance to Torin1, and 29 of these 62 genes have novel links to TOR signalling. The identification of chromatin and transcriptional regulation, nutritional uptake and transport pathways in this powerful genetic model now paves the way for a molecular understanding of how cells adapt to the chronic and acute fluctuations in nutrient supply that all eukaryotes experience at some stage, and which is a key feature of cancer cells within solid tumours.
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Affiliation(s)
- Shervi Lie
- Flinders Centre for Innovation in Cancer, College of Medicine & Public Health, Flinders University, Bedford Park, Adelaide, South Australia 5042, Australia
| | - Peter Banks
- High Throughput Screening Facility, Newcastle Biomedicine, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Conor Lawless
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - David Lydall
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - Janni Petersen
- Flinders Centre for Innovation in Cancer, College of Medicine & Public Health, Flinders University, Bedford Park, Adelaide, South Australia 5042, Australia .,South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide, South Australia 5000, Australia
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39
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Ahamad N, Sharma T, Khan S, Siddiqi MI, Ahmed S. Phosphorylation of Wat1, human Lst8 homolog is critical for the regulation of TORC2 –Gad8 dependent pathway in fission yeast Schizosacchromyces pombe. Eur J Cell Biol 2018; 97:300-307. [DOI: 10.1016/j.ejcb.2018.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 04/04/2018] [Accepted: 04/16/2018] [Indexed: 12/28/2022] Open
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40
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Cohen A, Habib A, Laor D, Yadav S, Kupiec M, Weisman R. TOR complex 2 in fission yeast is required for chromatin-mediated gene silencing and assembly of heterochromatic domains at subtelomeres. J Biol Chem 2018; 293:8138-8150. [PMID: 29632066 DOI: 10.1074/jbc.ra118.002270] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/14/2018] [Indexed: 12/21/2022] Open
Abstract
The conserved serine/threonine protein kinase target of rapamycin (TOR) is a major regulator of eukaryotic cellular and organismal growth and a valuable target for drug therapy. TOR forms the core of two evolutionary conserved complexes, TOR complex 1 (TORC1) and TORC2. In the fission yeast Schizosaccharomyces pombe, TORC2 responds to glucose levels and, by activating the protein kinase Gad8 (an orthologue of human AKT), is required for well-regulated cell cycle progression, starvation responses, and cell survival. Here, we report that TORC2-Gad8 is also required for gene silencing and the formation of heterochromatin at the S. pombe mating-type locus and at subtelomeric regions. Deletion of TORC2-Gad8 resulted in loss of the heterochromatic modification of histone 3 lysine 9 dimethylation (H3K9me2) and an increase in euchromatic modifications, including histone 3 lysine 4 trimethylation (H3K4me3) and histone 4 lysine 16 acetylation (H4K16Ac). Accumulation of RNA polymerase II (Pol II) at subtelomeric genes in TORC2-Gad8 mutant cells indicated a defect in silencing at the transcriptional level. Moreover, a concurrent decrease in histone 4 lysine 20 dimethylation (H4K20me2) suggested elevated histone turnover. Loss of gene silencing in cells lacking TORC2-Gad8 is partially suppressed by loss of the anti-silencer Epe1 and fully suppressed by loss of the Pol II-associated Paf1 complex, two chromatin regulators that have been implicated in heterochromatin stability and spreading. Taken together, our findings suggest that TORC2-Gad8 signaling contributes to epigenetic stability at subtelomeric regions and the mating-type locus in S. pombe.
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Affiliation(s)
- Adiel Cohen
- Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana, Israel
| | - Aline Habib
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Dana Laor
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Sudhanshu Yadav
- Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana, Israel
| | - Martin Kupiec
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69977801, Tel Aviv, Israel
| | - Ronit Weisman
- Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana, Israel.
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41
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Otsubo Y, Matsuo T, Nishimura A, Yamamoto M, Yamashita A. tRNA production links nutrient conditions to the onset of sexual differentiation through the TORC1 pathway. EMBO Rep 2018; 19:embr.201744867. [PMID: 29330317 DOI: 10.15252/embr.201744867] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/30/2017] [Accepted: 12/14/2017] [Indexed: 12/14/2022] Open
Abstract
Target of rapamycin (TOR) kinase controls cell growth and metabolism in response to nutrient availability. In the fission yeast Schizosaccharomyces pombe, TOR complex 1 (TORC1) promotes vegetative growth and inhibits sexual differentiation in the presence of ample nutrients. Here, we report the isolation and characterization of mutants with similar phenotypes as TORC1 mutants, in that they initiate sexual differentiation even in nutrient-rich conditions. In most mutants identified, TORC1 activity is downregulated and the mutated genes are involved in tRNA expression or modification. Expression of tRNA precursors decreases when cells undergo sexual differentiation. Furthermore, overexpression of tRNA precursors prevents TORC1 downregulation upon nitrogen starvation and represses the initiation of sexual differentiation. Based on these observations, we propose that tRNA precursors operate in the S. pombe TORC1 pathway to switch growth mode from vegetative to reproductive.
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Affiliation(s)
- Yoko Otsubo
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Tomohiko Matsuo
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Akiko Nishimura
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Masayuki Yamamoto
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Aichi, Japan.,Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan.,Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan
| | - Akira Yamashita
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Aichi, Japan .,Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan
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42
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Bhola T, Kapuy O, Vinod PK. Computational modelling of meiotic entry and commitment. Sci Rep 2018; 8:180. [PMID: 29317645 PMCID: PMC5760542 DOI: 10.1038/s41598-017-17478-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 11/24/2017] [Indexed: 01/25/2023] Open
Abstract
In response to developmental and environmental conditions, cells exit the mitotic cell cycle and enter the meiosis program to generate haploid gametes from diploid germ cells. Once cells decide to enter the meiosis program they become irreversibly committed to the completion of meiosis irrespective of the presence of cue signals. How meiotic entry and commitment occur due to the dynamics of the regulatory network is not well understood. Therefore, we constructed a mathematical model of the regulatory network that controls the transition from mitosis to meiosis in Schizosaccharomyces pombe. Upon nitrogen starvation, yeast cells exit mitosis and undergo conjugation and meiotic entry. The model includes the regulation of Mei2, an RNA binding protein required for conjugation and meiotic entry, by multiple feedback loops involving Pat1, a kinase that keeps cells in mitosis, and Ste11, a transcription activator required for the sexual differentiation. The model accounts for various experimental observations and demonstrates that the activation of Mei2 is bistable, which ensures the irreversible commitment to meiosis. Further, we show by integrating the meiosis-specific regulation with a cell cycle model, the dynamics of cell cycle exit, G1 arrest and entry into meiosis under nitrogen starvation.
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Affiliation(s)
- Tanvi Bhola
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad, 500032, India
| | - Orsolya Kapuy
- Semmelweis University, Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Budapest, Hungary
| | - P K Vinod
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad, 500032, India.
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43
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Chia KH, Fukuda T, Sofyantoro F, Matsuda T, Amai T, Shiozaki K. Ragulator and GATOR1 complexes promote fission yeast growth by attenuating TOR complex 1 through Rag GTPases. eLife 2017; 6:30880. [PMID: 29199950 PMCID: PMC5752196 DOI: 10.7554/elife.30880] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 12/02/2017] [Indexed: 12/18/2022] Open
Abstract
TOR complex 1 (TORC1) is an evolutionarily conserved protein kinase complex that promotes cellular macromolecular synthesis and suppresses autophagy. Amino-acid-induced activation of mammalian TORC1 is initiated by its recruitment to the RagA/B-RagC/D GTPase heterodimer, which is anchored to lysosomal membranes through the Ragulator complex. We have identified in the model organism Schizosaccharomyces pombe a Ragulator-like complex that tethers the Gtr1-Gtr2 Rag heterodimer to the membranes of vacuoles, the lysosome equivalent in yeasts. Unexpectedly, the Ragulator-Rag complex is not required for the vacuolar targeting of TORC1, but the complex plays a crucial role in attenuating TORC1 activity independently of the Tsc1-Tsc2 complex, a known negative regulator of TORC1 signaling. The GATOR1 complex, which functions as Gtr1 GAP, is essential for the TORC1 attenuation by the Ragulator-Rag complex, suggesting that Gtr1GDP-Gtr2 on vacuolar membranes moderates TORC1 signaling for optimal cellular response to nutrients.
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Affiliation(s)
- Kim Hou Chia
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Tomoyuki Fukuda
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan.,Department of Cellular Physiology, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Fajar Sofyantoro
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan.,Department of Animal Physiology, Faculty of Biology, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Takato Matsuda
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Takamitsu Amai
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Kazuhiro Shiozaki
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan.,Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, United States
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Laboucarié T, Detilleux D, Rodriguez-Mias RA, Faux C, Romeo Y, Franz-Wachtel M, Krug K, Maček B, Villén J, Petersen J, Helmlinger D. TORC1 and TORC2 converge to regulate the SAGA co-activator in response to nutrient availability. EMBO Rep 2017; 18:2197-2218. [PMID: 29079657 DOI: 10.15252/embr.201744942] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/31/2017] [Accepted: 09/07/2017] [Indexed: 12/19/2022] Open
Abstract
Gene expression regulation is essential for cells to adapt to changes in their environment. Co-activator complexes have well-established roles in transcriptional regulation, but less is known about how they sense and respond to signaling cues. We have previously shown that, in fission yeast, one such co-activator, the SAGA complex, controls gene expression and the switch from proliferation to differentiation in response to nutrient availability. Here, using a combination of genetic, biochemical, and proteomic approaches, we show that SAGA responds to nutrients through the differential phosphorylation of its Taf12 component, downstream of both the TORC1 and TORC2 pathways. Taf12 phosphorylation increases early upon starvation and is controlled by the opposing activities of the PP2A phosphatase, which is activated by TORC1, and the TORC2-activated Gad8AKT kinase. Mutational analyses suggest that Taf12 phosphorylation prevents cells from committing to differentiation until starvation reaches a critical level. Overall, our work reveals that SAGA is a direct target of nutrient-sensing pathways and has uncovered a mechanism by which TORC1 and TORC2 converge to control gene expression and cell fate decisions.
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Affiliation(s)
| | | | | | - Céline Faux
- CRBM, CNRS, University of Montpellier, Montpellier, France
| | - Yves Romeo
- CRBM, CNRS, University of Montpellier, Montpellier, France
| | | | | | - Boris Maček
- Proteome Center Tübingen, Tuebingen, Germany
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Janni Petersen
- Flinders Centre for Innovation in Cancer, School of Medicine, Faculty of Health Science, Flinders University, Adelaide, SA, Australia
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45
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Simonetti F, Candelli T, Leon S, Libri D, Rougemaille M. Ubiquitination-dependent control of sexual differentiation in fission yeast. eLife 2017; 6:28046. [PMID: 28841135 PMCID: PMC5614563 DOI: 10.7554/elife.28046] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/21/2017] [Indexed: 01/03/2023] Open
Abstract
In fission yeast, meiosis-specific transcripts are selectively eliminated during vegetative growth by the combined action of the YTH-family RNA-binding protein Mmi1 and the nuclear exosome. Upon nutritional starvation, the master regulator of meiosis Mei2 inactivates Mmi1, thereby allowing expression of the meiotic program. Here, we show that the E3 ubiquitin ligase subunit Not4/Mot2 of the evolutionarily conserved Ccr4-Not complex, which associates with Mmi1, promotes suppression of meiotic transcripts expression in mitotic cells. Our analyses suggest that Mot2 directs ubiquitination of Mei2 to preserve the activity of Mmi1 during vegetative growth. Importantly, Mot2 is not involved in the constitutive pathway of Mei2 turnover, but rather plays a regulatory role to limit its accumulation or inhibit its function. We propose that Mmi1 recruits the Ccr4-Not complex to counteract its own inhibitor Mei2, thereby locking the system in a stable state that ensures the repression of the meiotic program by Mmi1.
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Affiliation(s)
- Fabrizio Simonetti
- Institut Jacques Monod, Team "Metabolism and Function of RNA in the Nucleus", CNRS, UMR7592, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,Université Paris-Saclay, Gif-sur-Yvette, France
| | - Tito Candelli
- Institut Jacques Monod, Team "Metabolism and Function of RNA in the Nucleus", CNRS, UMR7592, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,Université Paris-Saclay, Gif-sur-Yvette, France
| | - Sebastien Leon
- Institut Jacques Monod, Team "Membrane Trafficking, Ubiquitin and Signaling", CNRS, UMR9198, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Domenico Libri
- Institut Jacques Monod, Team "Metabolism and Function of RNA in the Nucleus", CNRS, UMR7592, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Mathieu Rougemaille
- Institut Jacques Monod, Team "Metabolism and Function of RNA in the Nucleus", CNRS, UMR7592, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
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46
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Abstract
All organisms can respond to the availability of nutrients by regulating their metabolism, growth, and cell division. Central to the regulation of growth in response to nutrient availability is the target of rapamycin (TOR) signaling that is composed of two structurally distinct complexes: TOR complex 1 (TORC1) and TOR complex 2 (TORC2). The TOR genes were first identified in yeast as target of rapamycin, a natural product of a soil bacterium, which proved beneficial as an immunosuppressive and anticancer drug and is currently being tested for a handful of other pathological conditions including diabetes, neurodegeneration, and age-related diseases. Studies of the TOR pathway unraveled a complex growth-regulating network. TOR regulates nutrient uptake, transcription, protein synthesis and degradation, as well as metabolic pathways, in a coordinated manner that ensures that cells grow or cease growth in response to nutrient availability. The identification of specific signals and mechanisms that stimulate TOR signaling is an active and exciting field of research that has already identified nitrogen and amino acids as key regulators of TORC1 activity. The signals, as well as the cellular functions of TORC2, are far less well understood. Additional open questions in the field concern the relationships between TORC1 and TORC2, as well as the links with other nutrient-responsive pathways. Here I review the main features of TORC1 and TORC2, with a particular focus on yeasts as model organisms.
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Pérez-Hidalgo L, Moreno S. Coupling TOR to the Cell Cycle by the Greatwall-Endosulfine-PP2A-B55 Pathway. Biomolecules 2017; 7:biom7030059. [PMID: 28777780 PMCID: PMC5618240 DOI: 10.3390/biom7030059] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 07/31/2017] [Accepted: 08/02/2017] [Indexed: 01/14/2023] Open
Abstract
Cell growth and division are two processes tightly coupled in proliferating cells. While Target of Rapamycin (TOR) is the master regulator of growth, the cell cycle is dictated by the activity of the cyclin-dependent kinases (CDKs). A long-standing question in cell biology is how these processes may be connected. Recent work has highlighted that regulating the phosphatases that revert CDK phosphorylations is as important as regulating the CDKs for cell cycle progression. At mitosis, maintaining a low level of protein phosphatase 2A (PP2A)-B55 activity is essential for CDK substrates to achieve the correct level of phosphorylation. The conserved Greatwall–Endosulfine pathway has been shown to be required for PP2A-B55 inhibition at mitosis in yeasts and multicellular organisms. Interestingly, in yeasts, the Greatwall–Endosulfine pathway is negatively regulated by TOR Complex 1 (TORC1). Moreover, Greatwall–Endosulfine activation upon TORC1 inhibition has been shown to regulate the progression of the cell cycle at different points: the G1 phase in budding yeast, the G2/M transition and the differentiation response in fission yeast, and the entry into quiescence in both budding and fission yeasts. In this review, we discuss the recent findings on how the Greatwall–Endosulfine pathway may provide a connection between cell growth and the cell cycle machinery.
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Affiliation(s)
- Livia Pérez-Hidalgo
- Institute of Functional Biology and Genomics (IBFG), CSIC/University of Salamanca, 37007 Salamanca, Spain.
- Institute of Biomedical Research of Salamanca (IBSAL), University Hospital of Salamanca, 37007 Salamanca, Spain.
| | - Sergio Moreno
- Institute of Functional Biology and Genomics (IBFG), CSIC/University of Salamanca, 37007 Salamanca, Spain.
- Institute of Biomedical Research of Salamanca (IBSAL), University Hospital of Salamanca, 37007 Salamanca, Spain.
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TORC1-Dependent Phosphorylation Targets in Fission Yeast. Biomolecules 2017; 7:biom7030050. [PMID: 28671615 PMCID: PMC5618231 DOI: 10.3390/biom7030050] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 12/11/2022] Open
Abstract
Target of rapamycin (TOR) kinase controls cell metabolism and growth in response to environmental cues such as nutrients, growth factors, and stress. TOR kinase is widely conserved across eukaryotes. As in other organisms, the fission yeast Schizosaccharomyces pombe has two types of TOR complex, namely TOR complex 1 (TORC1) and TORC2. It is interesting that the two TOR complexes in S. pombe have opposite roles in sexual differentiation, which is induced by nutrient starvation. TORC1, which contains Tor2 as a catalytic subunit, promotes vegetative growth and represses sexual differentiation in nutrient-rich conditions, while TORC2 is required for the initiation of sexual differentiation. Multiple targets of TORC1 have been identified. Some of these, such as S6 kinase and an autophagy regulator Atg13, are known targets in other organisms. In addition, there is a novel group of TORC1 targets involved in the regulation of sexual differentiation. Here, we review recent findings on phosphorylation targets of TORC1 in S. pombe. Furthermore, we briefly report a novel S. pombe target of TORC1.
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49
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Abstract
The control of cell fate, growth and proliferation in response to nitrogen availability is a tightly controlled process, with the two TOR complexes (TORC1 and TORC2) and their effectors playing a central role. PP2A-B55Pab1 has recently been shown to be a key element in this response in fission yeast, where it regulates cell cycle progression and sexual differentiation. Importantly, a recent study from our group has shown that PP2A-B55Pab1 acts as a mediator between the activities of the two TOR signaling modules, enabling a crosstalk that is required to engage in the differentiation program. In this review, we recapitulate the studies that have led to our current understanding of the interplay between TOR complexes. Moreover, we discuss several aspects of the response to nitrogen availability that still require further attention, and which will be important in the future to fully realize the implications of phosphatase activity in the context of TOR signaling.
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Affiliation(s)
- Ruth Martín
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, Gaustadalleen 21, 0349, Oslo, Norway
| | - Sandra Lopez-Aviles
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, Gaustadalleen 21, 0349, Oslo, Norway.
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50
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Abstract
Replicative aging has been demonstrated in asymmetrically dividing unicellular organisms, seemingly caused by unequal damage partitioning. Although asymmetric segregation and inheritance of potential aging factors also occur in symmetrically dividing species, it nevertheless remains controversial whether this results in aging. Based on large-scale single-cell lineage data obtained by time-lapse microscopy with a microfluidic device, in this report, we demonstrate the absence of replicative aging in old-pole cell lineages of Schizosaccharomyces pombe cultured under constant favorable conditions. By monitoring more than 1,500 cell lineages in 7 different culture conditions, we showed that both cell division and death rates are remarkably constant for at least 50–80 generations. Our measurements revealed that the death rate per cellular generation increases with the division rate, pointing to a physiological trade-off with fast growth under balanced growth conditions. We also observed the formation and inheritance of Hsp104-associated protein aggregates, which are a potential aging factor in old-pole cell lineages, and found that these aggregates exhibited a tendency to preferentially remain at the old poles for several generations. However, the aggregates were eventually segregated from old-pole cells upon cell division and probabilistically allocated to new-pole cells. We found that cell deaths were typically preceded by sudden acceleration of protein aggregation; thus, a relatively large amount of protein aggregates existed at the very ends of the dead cell lineages. Our lineage tracking analyses, however, revealed that the quantity and inheritance of protein aggregates increased neither cellular generation time nor cell death initiation rates. Furthermore, our results demonstrated that unusually large amounts of protein aggregates induced by oxidative stress exposure did not result in aging; old-pole cells resumed normal growth upon stress removal, despite the fact that most of them inherited significant quantities of aggregates. These results collectively indicate that protein aggregates are not a major determinant of triggering cell death in S. pombe and thus cannot be an appropriate molecular marker or index for replicative aging under both favorable and stressful environmental conditions. Multicellular organisms universally senesce and must produce rejuvenated progenies in order to transmit life. Although similar age-related deterioration in physiological functions and reproduction is also found in unicellular organisms that divide asymmetrically to produce morphologically distinct aged and younger cells, it has been unclear whether symmetrically dividing microbes—such as fission yeast—exhibit the same traits. Using long-term live-cell microscopy combined with a microfluidic device, we monitor the growth and death of a large number of fission yeast cells and demonstrate the existence of aging-free lineages. These lineages are, however, not immortal, and the probability of death increases as the cells grow more rapidly; thus, the “live fast, die fast” trade-off exists in fission yeast. We further characterize the segregation and inheritance of protein aggregates, which are commonly thought of as “aging factors.” The aging-free lineages bear the aggregate load for some generations with no apparent adverse effects on growth. We also show that there is no threshold amount of protein aggregate above which cells are destined to death in both normal and stressed conditions: protein aggregate is thus not a direct initiation signal for cell death. Our data reveal that protein aggregation might not be an appropriate index for aging and that we should revisit its role in cell physiology.
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Affiliation(s)
- Hidenori Nakaoka
- Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan
| | - Yuichi Wakamoto
- Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan
- Research Center for Complex Systems Biology, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan
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