1
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Naaz A, Zhang Y, Faidzinn NA, Yogasundaram S, Dorajoo R, Alfatah M. Curcumin Inhibits TORC1 and Prolongs the Lifespan of Cells with Mitochondrial Dysfunction. Cells 2024; 13:1470. [PMID: 39273040 PMCID: PMC11394456 DOI: 10.3390/cells13171470] [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: 07/18/2024] [Revised: 08/24/2024] [Accepted: 08/30/2024] [Indexed: 09/15/2024] Open
Abstract
Aging is an inevitable biological process that contributes to the onset of age-related diseases, often as a result of mitochondrial dysfunction. Understanding the mechanisms behind aging is crucial for developing therapeutic interventions. This study investigates the effects of curcumin on postmitotic cellular lifespan (PoMiCL) during chronological aging in yeast, a widely used model for human postmitotic cellular aging. Our findings reveal that curcumin significantly prolongs the PoMiCL of wildtype yeast cells, with the most pronounced effects observed at lower concentrations, indicating a hormetic response. Importantly, curcumin also extends the lifespan of postmitotic cells with mitochondrial deficiencies, although the hormetic effect is absent in these defective cells. Mechanistically, curcumin inhibits TORC1 activity, enhances ATP levels, and induces oxidative stress. These results suggest that curcumin has the potential to modulate aging and offer therapeutic insights into age-related diseases, highlighting the importance of context in its effects.
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Affiliation(s)
- Arshia Naaz
- Genome Institute of Singapore (GIS), Agency for Science, Technology and Research (A*STAR), Singapore 138672, Singapore
| | - Yizhong Zhang
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore
| | - Nashrul Afiq Faidzinn
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore
| | - Sonia Yogasundaram
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore
| | - Rajkumar Dorajoo
- Genome Institute of Singapore (GIS), Agency for Science, Technology and Research (A*STAR), Singapore 138672, Singapore
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Mohammad Alfatah
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), Singapore 138671, Singapore
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117544, Singapore
- Centre for Healthy Longevity, National University Health System, Singapore 117456, Singapore
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2
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Lucca C, Ferrari E, Shubassi G, Ajazi A, Choudhary R, Bruhn C, Matafora V, Bachi A, Foiani M. Sch9 S6K controls DNA repair and DNA damage response efficiency in aging cells. Cell Rep 2024; 43:114281. [PMID: 38805395 DOI: 10.1016/j.celrep.2024.114281] [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: 12/08/2023] [Revised: 04/10/2024] [Accepted: 05/10/2024] [Indexed: 05/30/2024] Open
Abstract
Survival from UV-induced DNA lesions relies on nucleotide excision repair (NER) and the Mec1ATR DNA damage response (DDR). We study DDR and NER in aging cells and find that old cells struggle to repair DNA and activate Mec1ATR. We employ pharmacological and genetic approaches to rescue DDR and NER during aging. Conditions activating Snf1AMPK rescue DDR functionality, but not NER, while inhibition of the TORC1-Sch9S6K axis restores NER and enhances DDR by tuning PP2A activity, specifically in aging cells. Age-related repair deficiency depends on Snf1AMPK-mediated phosphorylation of Sch9S6K on Ser160 and Ser163. PP2A activity in old cells is detrimental for DDR and influences NER by modulating Snf1AMPK and Sch9S6K. Hence, the DDR and repair pathways in aging cells are influenced by the metabolic tuning of opposing AMPK and TORC1 networks and by PP2A activity. Specific Sch9S6K phospho-isoforms control DDR and NER efficiency, specifically during aging.
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Affiliation(s)
- Chiara Lucca
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Elisa Ferrari
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy.
| | - Ghadeer Shubassi
- AtomVie Global Radiopharma Inc., 1280 Main Street W NRB-A316, Hamilton, ON L8S-4K1, Canada
| | - Arta Ajazi
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Ramveer Choudhary
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Christopher Bruhn
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Vittoria Matafora
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Angela Bachi
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Marco Foiani
- IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy; Istituto di Genetica Molecolare, CNR, Pavia, Italy.
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3
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Ma L, Ma J, Tian Y, Li X, Tai B, Xing F. Fus3 Interacts with Gal83, Revealing the MAPK Crosstalk to Snf1/AMPK to Regulate Secondary Metabolic Substrates in Aspergillus flavus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:10065-10075. [PMID: 38634532 DOI: 10.1021/acs.jafc.4c01229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/19/2024]
Abstract
Aflatoxins (AFs), highly carcinogenic natural products, are produced by the secondary metabolism of fungi such as Aspergillus flavus. Essential for the fungi to respond to environmental changes and aflatoxin synthesis, the pheromone mitogen-activated protein kinase (MAPK) is a potential regulator of aflatoxin biosynthesis. However, the mechanism by which pheromone MAPK regulates aflatoxin biosynthesis is not clear. Here, we showed Gal83, a new target of Fus3, and identified the pheromone Fus3-MAPK signaling pathway as a regulator of the Snf1/AMPK energy-sensing pathway modulating aflatoxins synthesis substrates. The screening for Fus3 target proteins identified the β subunit of Snf1/AMPK complexes using tandem affinity purification and multiomics. This subunit physically interacted with Fus3 both in vivo and in vitro and received phosphorylation from Fus3. Although the transcript levels of aflatoxin synthesis genes were not noticeably downregulated in both gal83 and fus3 deletion mutant strains, the levels of aflatoxin B1 and its synthesis substrates and gene expression levels of primary metabolizing enzymes were significantly reduced. This suggests that both the Fus3-MAPK and Snf1/AMPK pathways respond to energy signals. In conclusion, all the evidence unlocks a novel pathway of Fus3-MAPK to regulate AFs synthesis substrates by cross-talking with the Snf1/AMPK complexes.
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Affiliation(s)
- Longxue Ma
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Junning Ma
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Yuanyuan Tian
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Xu Li
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Bowen Tai
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Fuguo Xing
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
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4
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Niphadkar S, Karinje L, Laxman S. The PP2A-like phosphatase Ppg1 mediates assembly of the Far complex to balance gluconeogenic outputs and enables adaptation to glucose depletion. PLoS Genet 2024; 20:e1011202. [PMID: 38452140 PMCID: PMC10950219 DOI: 10.1371/journal.pgen.1011202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 03/19/2024] [Accepted: 02/27/2024] [Indexed: 03/09/2024] Open
Abstract
To sustain growth in changing nutrient conditions, cells reorganize outputs of metabolic networks and appropriately reallocate resources. Signaling by reversible protein phosphorylation can control such metabolic adaptations. In contrast to kinases, the functions of phosphatases that enable metabolic adaptation as glucose depletes are poorly studied. Using a Saccharomyces cerevisiae deletion screen, we identified the PP2A-like phosphatase Ppg1 as required for appropriate carbon allocations towards gluconeogenic outputs-trehalose, glycogen, UDP-glucose, UDP-GlcNAc-after glucose depletion. This Ppg1 function is mediated via regulation of the assembly of the Far complex-a multi-subunit complex that tethers to the ER and mitochondrial outer membranes forming localized signaling hubs. The Far complex assembly is Ppg1 catalytic activity-dependent. Ppg1 regulates the phosphorylation status of multiple ser/thr residues on Far11 to enable the proper assembly of the Far complex. The assembled Far complex is required to maintain gluconeogenic outputs after glucose depletion. Glucose in turn regulates Far complex amounts. This Ppg1-mediated Far complex assembly, and Ppg1-Far complex dependent control of gluconeogenic outputs enables adaptive growth under glucose depletion. Our study illustrates how protein dephosphorylation is required for the assembly of a multi-protein scaffold present in localized cytosolic pools, to thereby alter gluconeogenic flux and enable cells to metabolically adapt to nutrient fluctuations.
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Affiliation(s)
- Shreyas Niphadkar
- Institute for Stem Cell Science and Regenerative Medicine (DBT-inStem) Bangalore, India
- Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Lavanya Karinje
- Institute for Stem Cell Science and Regenerative Medicine (DBT-inStem) Bangalore, India
| | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine (DBT-inStem) Bangalore, India
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5
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Williams TD, Rousseau A. Translation regulation in response to stress. FEBS J 2024. [PMID: 38308808 DOI: 10.1111/febs.17076] [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: 11/09/2023] [Revised: 12/07/2023] [Accepted: 01/22/2024] [Indexed: 02/05/2024]
Abstract
Cell stresses occur in a wide variety of settings: in disease, during industrial processes, and as part of normal day-to-day rhythms. Adaptation to these stresses requires cells to alter their proteome. Cells modify the proteins they synthesize to aid proteome adaptation. Changes in both mRNA transcription and translation contribute to altered protein synthesis. Here, we discuss the changes in translational mechanisms that occur following the onset of stress, and the impact these have on stress adaptation.
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Affiliation(s)
- Thomas D Williams
- MRC-PPU, School of Life Sciences, University of Dundee, UK
- Sir William Dunn School of Pathology, University of Oxford, UK
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6
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Metur SP, Klionsky DJ. Nutrient-dependent signaling pathways that control autophagy in yeast. FEBS Lett 2024; 598:32-47. [PMID: 37758520 PMCID: PMC10841420 DOI: 10.1002/1873-3468.14741] [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: 07/26/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/29/2023]
Abstract
Macroautophagy/autophagy is a highly conserved catabolic process vital for cellular stress responses and maintaining equilibrium within the cell. Malfunctioning autophagy has been implicated in the pathogenesis of various diseases, including certain neurodegenerative disorders, diabetes, metabolic diseases, and cancer. Cells face diverse metabolic challenges, such as limitations in nitrogen, carbon, and minerals such as phosphate and iron, necessitating the integration of complex metabolic information. Cells utilize a signal transduction network of sensors, transducers, and effectors to coordinate the execution of the autophagic response, concomitant with the severity of the nutrient-starvation condition. This review presents the current mechanistic understanding of how cells regulate the initiation of autophagy through various nutrient-dependent signaling pathways. Emphasizing findings from studies in yeast, we explore the emerging principles that underlie the nutrient-dependent regulation of autophagy, significantly shaping stress-induced autophagy responses under various metabolic stress conditions.
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Affiliation(s)
- Shree Padma Metur
- Department of Molecular, Cellular and Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Daniel J Klionsky
- Department of Molecular, Cellular and Developmental Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
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7
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Alfatah M, Cui L, Goh CJH, Cheng TYN, Zhang Y, Naaz A, Wong JH, Lewis J, Poh WJ, Arumugam P. Metabolism of glucose activates TORC1 through multiple mechanisms in Saccharomyces cerevisiae. Cell Rep 2023; 42:113205. [PMID: 37792530 DOI: 10.1016/j.celrep.2023.113205] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/30/2023] [Accepted: 09/18/2023] [Indexed: 10/06/2023] Open
Abstract
Target of Rapamycin Complex 1 (TORC1) is a conserved eukaryotic protein complex that links the presence of nutrients with cell growth. In Saccharomyces cerevisiae, TORC1 activity is positively regulated by the presence of amino acids and glucose in the medium. However, the mechanisms underlying nutrient-induced TORC1 activation remain poorly understood. By utilizing an in vivo TORC1 activation assay, we demonstrate that differential metabolism of glucose activates TORC1 through three distinct pathways in yeast. The first "canonical Rag guanosine triphosphatase (GTPase)-dependent pathway" requires conversion of glucose to fructose 1,6-bisphosphate, which activates TORC1 via the Rag GTPase heterodimer Gtr1GTP-Gtr2GDP. The second "non-canonical Rag GTPase-dependent pathway" requires conversion of glucose to glucose 6-phosphate, which activates TORC1 via a process that involves Gtr1GTP-Gtr2GTP and mitochondrial function. The third "Rag GTPase-independent pathway" requires complete glycolysis and vacuolar ATPase reassembly for TORC1 activation. We have established a roadmap to deconstruct the link between glucose metabolism and TORC1 activation.
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Affiliation(s)
- Mohammad Alfatah
- Bioinformatics Institute, A(∗)STAR, 30 Biopolis Street, Singapore 138671, Singapore.
| | - Liang Cui
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, Singapore 138602, Singapore
| | - Corinna Jie Hui Goh
- Bioinformatics Institute, A(∗)STAR, 30 Biopolis Street, Singapore 138671, Singapore
| | | | - Yizhong Zhang
- Bioinformatics Institute, A(∗)STAR, 30 Biopolis Street, Singapore 138671, Singapore
| | - Arshia Naaz
- Genome Institute of Singapore, A(∗)STAR, 60 Biopolis Street, Genome #02-01, Singapore 138672, Singapore
| | - Jin Huei Wong
- Bioinformatics Institute, A(∗)STAR, 30 Biopolis Street, Singapore 138671, Singapore
| | - Jacqueline Lewis
- Institute of Molecular and Cellular Biology, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Wei Jie Poh
- Bioinformatics Institute, A(∗)STAR, 30 Biopolis Street, Singapore 138671, Singapore
| | - Prakash Arumugam
- Singapore Institute of Food and Biotechnology Innovation, A(∗)STAR, 31 Biopolis Way, Singapore 138669, Singapore; Nanyang Technological University, School of Biological Sciences, Singapore 637551, Singapore.
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8
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Foltman M, Sanchez-Diaz A. TOR Complex 1: Orchestrating Nutrient Signaling and Cell Cycle Progression. Int J Mol Sci 2023; 24:15745. [PMID: 37958727 PMCID: PMC10647266 DOI: 10.3390/ijms242115745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/26/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023] Open
Abstract
The highly conserved TOR signaling pathway is crucial for coordinating cellular growth with the cell cycle machinery in eukaryotes. One of the two TOR complexes in budding yeast, TORC1, integrates environmental cues and promotes cell growth. While cells grow, they need to copy their chromosomes, segregate them in mitosis, divide all their components during cytokinesis, and finally physically separate mother and daughter cells to start a new cell cycle apart from each other. To maintain cell size homeostasis and chromosome stability, it is crucial that mechanisms that control growth are connected and coordinated with the cell cycle. Successive periods of high and low TORC1 activity would participate in the adequate cell cycle progression. Here, we review the known molecular mechanisms through which TORC1 regulates the cell cycle in the budding yeast Saccharomyces cerevisiae that have been extensively used as a model organism to understand the role of its mammalian ortholog, mTORC1.
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Affiliation(s)
- Magdalena Foltman
- Mechanisms and Regulation of Cell Division Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, 39011 Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Spain
| | - Alberto Sanchez-Diaz
- Mechanisms and Regulation of Cell Division Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, 39011 Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Spain
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9
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Caligaris M, Sampaio-Marques B, Hatakeyama R, Pillet B, Ludovico P, De Virgilio C, Winderickx J, Nicastro R. The Yeast Protein Kinase Sch9 Functions as a Central Nutrient-Responsive Hub That Calibrates Metabolic and Stress-Related Responses. J Fungi (Basel) 2023; 9:787. [PMID: 37623558 PMCID: PMC10455444 DOI: 10.3390/jof9080787] [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: 05/30/2023] [Revised: 07/20/2023] [Accepted: 07/24/2023] [Indexed: 08/26/2023] Open
Abstract
Yeast cells are equipped with different nutrient signaling pathways that enable them to sense the availability of various nutrients and adjust metabolism and growth accordingly. These pathways are part of an intricate network since most of them are cross-regulated and subject to feedback regulation at different levels. In yeast, a central role is played by Sch9, a protein kinase that functions as a proximal effector of the conserved growth-regulatory TORC1 complex to mediate information on the availability of free amino acids. However, recent studies established that Sch9 is more than a TORC1-effector as its activity is tuned by several other kinases. This allows Sch9 to function as an integrator that aligns different input signals to achieve accuracy in metabolic responses and stress-related molecular adaptations. In this review, we highlight the latest findings on the structure and regulation of Sch9, as well as its role as a nutrient-responsive hub that impacts on growth and longevity of yeast cells. Given that most key players impinging on Sch9 are well-conserved, we also discuss how studies on Sch9 can be instrumental to further elucidate mechanisms underpinning healthy aging in mammalians.
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Affiliation(s)
- Marco Caligaris
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland; (M.C.); (B.P.); (C.D.V.)
| | - Belém Sampaio-Marques
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal; (B.S.-M.); (P.L.)
- ICVS/3B’s-PT Government Associate Laboratory, 4806-909 Guimarães, Portugal
| | - Riko Hatakeyama
- Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK;
| | - Benjamin Pillet
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland; (M.C.); (B.P.); (C.D.V.)
| | - Paula Ludovico
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal; (B.S.-M.); (P.L.)
- ICVS/3B’s-PT Government Associate Laboratory, 4806-909 Guimarães, Portugal
| | - Claudio De Virgilio
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland; (M.C.); (B.P.); (C.D.V.)
| | - Joris Winderickx
- Department of Biology, Functional Biology, KU Leuven, B-3001 Heverlee, Belgium;
| | - Raffaele Nicastro
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland; (M.C.); (B.P.); (C.D.V.)
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10
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Opalek M, Tutaj H, Pirog A, Smug BJ, Rutkowska J, Wloch-Salamon D. A Systematic Review on Quiescent State Research Approaches in S. cerevisiae. Cells 2023; 12:1608. [PMID: 37371078 DOI: 10.3390/cells12121608] [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: 05/03/2023] [Revised: 06/02/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Quiescence, the temporary and reversible arrest of cell growth, is a fundamental biological process. However, the lack of standardization in terms of reporting the experimental details of quiescent cells and populations can cause confusion and hinder knowledge transfer. We employ the systematic review methodology to comprehensively analyze the diversity of approaches used to study the quiescent state, focusing on all published research addressing the budding yeast Saccharomyces cerevisiae. We group research articles into those that consider all cells comprising the stationary-phase (SP) population as quiescent and those that recognize heterogeneity within the SP by distinguishing phenotypically distinct subpopulations. Furthermore, we investigate the chronological age of the quiescent populations under study and the methods used to induce the quiescent state, such as gradual starvation or abrupt environmental change. We also assess whether the strains used in research are prototrophic or auxotrophic. By combining the above features, we identify 48 possible experimental setups that can be used to study quiescence, which can be misleading when drawing general conclusions. We therefore summarize our review by proposing guidelines and recommendations pertaining to the information included in research articles. We believe that more rigorous reporting on the features of quiescent populations will facilitate knowledge transfer within and between disciplines, thereby stimulating valuable scientific discussion.
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Affiliation(s)
- Monika Opalek
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
| | - Hanna Tutaj
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
| | - Adrian Pirog
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
| | - Bogna J Smug
- Malopolska Centre of Biotechnology, Jagiellonian University, 30-387 Krakow, Poland
| | - Joanna Rutkowska
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
| | - Dominika Wloch-Salamon
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, 30-387 Krakow, Poland
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11
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Maynard CW, Gilbert E, Yan F, Cline MA, Dridi S. Peripheral and Central Impact of Methionine Source and Level on Growth Performance, Circulating Methionine Levels and Metabolism in Broiler Chickens. Animals (Basel) 2023; 13:1961. [PMID: 37370471 DOI: 10.3390/ani13121961] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 05/22/2023] [Accepted: 05/30/2023] [Indexed: 06/29/2023] Open
Abstract
The present study was designed to evaluate the effects of DL-methionine (DL-Met) 2-hydroxy-4-(methylthio) butanoic acid (HMTBa), or S-(5'-Adenosyl)-L-methionine chloride (SAM), using feeding trial and central administration, on live performance, plasma metabolites, and the expression of feeding-related hypothalamic neuropeptides in broilers raised to a market age (35 d). Final average body weight (BW) and feed conversion ratio (FCR) from the feeding trial exceeded the performance measurements published by the primary breeder. At d35, the MTBHa group had better BW and lower feed intake, which resulted in a better FCR than the DL-Met group at 87 TSAA to lysine. At the molecular levels, the expression of hypothalamic neuropeptide (NPY) and monocarboxylate transporter (MCT) 2 did not differ between all treated groups; however, the mRNA abundances of hypothalamic MCT1 and orexin (ORX) were significantly upregulated in DL-Met- treated groups compared to the control. The ICV administration of SAM significantly reduced feed intake at all tested periods (from 30 to 180 min post injection) compared to the aCSF-treated group (control). The central administration of HMTBa increased feed intake, which reached a significant level only 60 min post administration, compared to the control group. ICV administration of DL-Met slightly increased feed intake compared to the control group, but the difference was not statistically discernable. Quantitative real-time PCR analysis showed that the hypothalamic expression of NPY, cocaine- and amphetamine-regulated transcript, MCT1, and MCT2 was significantly upregulated in the ICV-HMTBa group compared to the aCSF birds. The hypothalamic expression of the mechanistic target of rapamycin (mTOR), AMP-activated protein kinase (AMPKα1), D-amino acid oxidase, and hydroxyacid oxidase was significantly upregulated in DL-Met compared to the control group. The mRNA abundances of ORX were significantly increased in the hypothalamus of both DL-Met and HMTBa groups compared to the aCSF birds; however, mTOR gene expression was significantly downregulated in the SAM compared to the control group. Taken together, these data show, for the first time, that DL-Met and HMTBa have a common downstream (ORX) pathway, but also a differential central pathway, typically NPY-MCT for HMTBa and mTOR-AMPK for methionine.
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Affiliation(s)
- Craig W Maynard
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA
| | - Elizabeth Gilbert
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Frances Yan
- Novus International, Saint Charles, MO 63304, USA
| | - Mark A Cline
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Sami Dridi
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA
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12
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Uvdal P, Shashkova S. The Effect of Calorie Restriction on Protein Quality Control in Yeast. Biomolecules 2023; 13:biom13050841. [PMID: 37238710 DOI: 10.3390/biom13050841] [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: 03/27/2023] [Revised: 04/30/2023] [Accepted: 05/01/2023] [Indexed: 05/28/2023] Open
Abstract
Initially, protein aggregates were regarded as a sign of a pathological state of the cell. Later, it was found that these assemblies are formed in response to stress, and that some of them serve as signalling mechanisms. This review has a particular focus on how intracellular protein aggregates are related to altered metabolism caused by different glucose concentrations in the extracellular environment. We summarise the current knowledge of the role of energy homeostasis signalling pathways in the consequent effect on intracellular protein aggregate accumulation and removal. This covers regulation at different levels, including elevated protein degradation and proteasome activity mediated by the Hxk2 protein, the enhanced ubiquitination of aberrant proteins through Torc1/Sch9 and Msn2/Whi2, and the activation of autophagy mediated through ATG genes. Finally, certain proteins form reversible biomolecular aggregates in response to stress and reduced glucose levels, which are used as a signalling mechanism in the cell, controlling major primary energy pathways related to glucose sensing.
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Affiliation(s)
- Petter Uvdal
- Department of Physics, University of Gothenburg, 405 30 Göteborg, Sweden
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13
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Pérez-Díaz AJ, Vázquez-Marín B, Vicente-Soler J, Prieto-Ruiz F, Soto T, Franco A, Cansado J, Madrid M. cAMP-Protein kinase A and stress-activated MAP kinase signaling mediate transcriptional control of autophagy in fission yeast during glucose limitation or starvation. Autophagy 2023; 19:1311-1331. [PMID: 36107819 PMCID: PMC10012941 DOI: 10.1080/15548627.2022.2125204] [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: 03/31/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 11/02/2022] Open
Abstract
Macroautophagy/autophagy is an essential adaptive physiological response in eukaryotes induced during nutrient starvation, including glucose, the primary immediate carbon and energy source for most cells. Although the molecular mechanisms that induce autophagy during glucose starvation have been extensively explored in the budding yeast Saccharomyces cerevisiae, little is known about how this coping response is regulated in the evolutionary distant fission yeast Schizosaccharomyces pombe. Here, we show that S. pombe autophagy in response to glucose limitation relies on mitochondrial respiration and the electron transport chain (ETC), but, in contrast to S. cerevisiae, the AMP-activated protein kinase (AMPK) and DNA damage response pathway components do not modulate fission yeast autophagic flux under these conditions. In the presence of glucose, the cAMP-protein kinase A (PKA) signaling pathway constitutively represses S. pombe autophagy by downregulating the transcription factor Rst2, which promotes the expression of respiratory genes required for autophagy induction under limited glucose availability. Furthermore, the stress-activated protein kinase (SAPK) signaling pathway, and its central mitogen-activated protein kinase (MAPK) Sty1, positively modulate autophagy upon glucose limitation at the transcriptional level through its downstream effector Atf1 and by direct in vivo phosphorylation of Rst2 at S292. Thus, our data indicate that the signaling pathways that govern autophagy during glucose shortage or starvation have evolved differently in S. pombe and uncover the existence of sophisticated and multifaceted mechanisms that control this self-preservation and survival response.
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Affiliation(s)
- Armando Jesús Pérez-Díaz
- Yeast Physiology Group. Department of Genetics and Microbiology. Campus de Excelencia Internacional de Ámbito Regional (CEIR) Campus Mare Nostrum, Universidad de Murcia, Murcia, Spain
| | - Beatriz Vázquez-Marín
- Yeast Physiology Group. Department of Genetics and Microbiology. Campus de Excelencia Internacional de Ámbito Regional (CEIR) Campus Mare Nostrum, Universidad de Murcia, Murcia, Spain
| | - Jero Vicente-Soler
- Yeast Physiology Group. Department of Genetics and Microbiology. Campus de Excelencia Internacional de Ámbito Regional (CEIR) Campus Mare Nostrum, Universidad de Murcia, Murcia, Spain
| | - Francisco Prieto-Ruiz
- Yeast Physiology Group. Department of Genetics and Microbiology. Campus de Excelencia Internacional de Ámbito Regional (CEIR) Campus Mare Nostrum, Universidad de Murcia, Murcia, Spain
| | - Teresa Soto
- Yeast Physiology Group. Department of Genetics and Microbiology. Campus de Excelencia Internacional de Ámbito Regional (CEIR) Campus Mare Nostrum, Universidad de Murcia, Murcia, Spain
| | - Alejandro Franco
- Yeast Physiology Group. Department of Genetics and Microbiology. Campus de Excelencia Internacional de Ámbito Regional (CEIR) Campus Mare Nostrum, Universidad de Murcia, Murcia, Spain
| | - José Cansado
- Yeast Physiology Group. Department of Genetics and Microbiology. Campus de Excelencia Internacional de Ámbito Regional (CEIR) Campus Mare Nostrum, Universidad de Murcia, Murcia, Spain
| | - Marisa Madrid
- Yeast Physiology Group. Department of Genetics and Microbiology. Campus de Excelencia Internacional de Ámbito Regional (CEIR) Campus Mare Nostrum, Universidad de Murcia, Murcia, Spain
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14
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Prouteau M, Bourgoint C, Felix J, Bonadei L, Sadian Y, Gabus C, Savvides SN, Gutsche I, Desfosses A, Loewith R. EGOC inhibits TOROID polymerization by structurally activating TORC1. Nat Struct Mol Biol 2023; 30:273-285. [PMID: 36702972 PMCID: PMC10023571 DOI: 10.1038/s41594-022-00912-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 11/21/2022] [Indexed: 01/27/2023]
Abstract
Target of rapamycin complex 1 (TORC1) is a protein kinase controlling cell homeostasis and growth in response to nutrients and stresses. In Saccharomyces cerevisiae, glucose depletion triggers a redistribution of TORC1 from a dispersed localization over the vacuole surface into a large, inactive condensate called TOROID (TORC1 organized in inhibited domains). However, the mechanisms governing this transition have been unclear. Here, we show that acute depletion and repletion of EGO complex (EGOC) activity is sufficient to control TOROID distribution, independently of other nutrient-signaling pathways. The 3.9-Å-resolution structure of TORC1 from TOROID cryo-EM data together with interrogation of key interactions in vivo provide structural insights into TORC1-TORC1' and TORC1-EGOC interaction interfaces. These data support a model in which glucose-dependent activation of EGOC triggers binding to TORC1 at an interface required for TOROID assembly, preventing TORC1 polymerization and promoting release of active TORC1.
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Affiliation(s)
- Manoël Prouteau
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland.
| | - Clélia Bourgoint
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
| | - Jan Felix
- Unit for Structural Biology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium.
- Unit for Structural Biology, VIB-UGent Center for Inflammation Research, Ghent, Belgium.
| | - Lenny Bonadei
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
| | - Yashar Sadian
- CryoGEnic facility (DCI Geneva), University of Geneva, Geneva, Switzerland
| | - Caroline Gabus
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
| | - Savvas N Savvides
- Unit for Structural Biology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
- Unit for Structural Biology, VIB-UGent Center for Inflammation Research, Ghent, Belgium
| | - Irina Gutsche
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Ambroise Desfosses
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Robbie Loewith
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland.
- Swiss National Centre for Competence in Research Chemical Biology, Geneva, Switzerland.
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15
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Caligaris M, Nicastro R, Hu Z, Tripodi F, Hummel JE, Pillet B, Deprez MA, Winderickx J, Rospert S, Coccetti P, Dengjel J, De Virgilio C. Snf1/AMPK fine-tunes TORC1 signaling in response to glucose starvation. eLife 2023; 12:84319. [PMID: 36749016 PMCID: PMC9937656 DOI: 10.7554/elife.84319] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 02/06/2023] [Indexed: 02/08/2023] Open
Abstract
The AMP-activated protein kinase (AMPK) and the target of rapamycin complex 1 (TORC1) are central kinase modules of two opposing signaling pathways that control eukaryotic cell growth and metabolism in response to the availability of energy and nutrients. Accordingly, energy depletion activates AMPK to inhibit growth, while nutrients and high energy levels activate TORC1 to promote growth. Both in mammals and lower eukaryotes such as yeast, the AMPK and TORC1 pathways are wired to each other at different levels, which ensures homeostatic control of growth and metabolism. In this context, a previous study (Hughes Hallett et al., 2015) reported that AMPK in yeast, that is Snf1, prevents the transient TORC1 reactivation during the early phase following acute glucose starvation, but the underlying mechanism has remained elusive. Using a combination of unbiased mass spectrometry (MS)-based phosphoproteomics, genetic, biochemical, and physiological experiments, we show here that Snf1 temporally maintains TORC1 inactive in glucose-starved cells primarily through the TORC1-regulatory protein Pib2. Our data, therefore, extend the function of Pib2 to a hub that integrates both glucose and, as reported earlier, glutamine signals to control TORC1. We further demonstrate that Snf1 phosphorylates the TORC1 effector kinase Sch9 within its N-terminal region and thereby antagonizes the phosphorylation of a C-terminal TORC1-target residue within Sch9 itself that is critical for its activity. The consequences of Snf1-mediated phosphorylation of Pib2 and Sch9 are physiologically additive and sufficient to explain the role of Snf1 in short-term inhibition of TORC1 in acutely glucose-starved cells.
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Affiliation(s)
- Marco Caligaris
- Department of Biology, University of FribourgFribourgSwitzerland
| | | | - Zehan Hu
- Department of Biology, University of FribourgFribourgSwitzerland
| | - Farida Tripodi
- Department of Biotechnology and Biosciences, University of Milano-BicoccaMilanoItaly
| | - Johannes Erwin Hummel
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of FreiburgFreiburgGermany
| | - Benjamin Pillet
- Department of Biology, University of FribourgFribourgSwitzerland
| | | | | | - Sabine Rospert
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of FreiburgFreiburgGermany,Signalling Research Centres BIOSS and CIBSS, University of FreiburgFreiburgGermany
| | - Paola Coccetti
- Department of Biotechnology and Biosciences, University of Milano-BicoccaMilanoItaly
| | - Jörn Dengjel
- Department of Biology, University of FribourgFribourgSwitzerland
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16
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Gutierrez-Beltran E, Crespo JL. Compartmentalization, a key mechanism controlling the multitasking role of the SnRK1 complex. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:7055-7067. [PMID: 35861169 PMCID: PMC9664234 DOI: 10.1093/jxb/erac315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
SNF1-related protein kinase 1 (SnRK1), the plant ortholog of mammalian AMP-activated protein kinase/fungal (yeast) Sucrose Non-Fermenting 1 (AMPK/SNF1), plays a central role in metabolic responses to reduced energy levels in response to nutritional and environmental stresses. SnRK1 functions as a heterotrimeric complex composed of a catalytic α- and regulatory β- and βγ-subunits. SnRK1 is a multitasking protein involved in regulating various cellular functions, including growth, autophagy, stress response, stomatal development, pollen maturation, hormone signaling, and gene expression. However, little is known about the mechanism whereby SnRK1 ensures differential execution of downstream functions. Compartmentalization has been recently proposed as a new key mechanism for regulating SnRK1 signaling in response to stimuli. In this review, we discuss the multitasking role of SnRK1 signaling associated with different subcellular compartments.
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Affiliation(s)
| | - Jose L Crespo
- Instituto de Bioquimica Vegetal y Fotosintesis, Consejo Superior de Investigaciones Cientificas (CSIC)-Universidad de Sevilla, Sevilla, Spain
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17
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Zhu J, Wang H, Jiang X. mTORC1 beyond anabolic metabolism: Regulation of cell death. J Biophys Biochem Cytol 2022; 221:213609. [PMID: 36282248 PMCID: PMC9606688 DOI: 10.1083/jcb.202208103] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 10/03/2022] [Accepted: 10/04/2022] [Indexed: 12/13/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1), a multi-subunit protein kinase complex, interrogates growth factor signaling with cellular nutrient and energy status to control metabolic homeostasis. Activation of mTORC1 promotes biosynthesis of macromolecules, including proteins, lipids, and nucleic acids, and simultaneously suppresses catabolic processes such as lysosomal degradation of self-constituents and extracellular components. Metabolic regulation has emerged as a critical determinant of various cellular death programs, including apoptosis, pyroptosis, and ferroptosis. In this article, we review the expanding knowledge on how mTORC1 coordinates metabolic pathways to impinge on cell death regulation. We focus on the current understanding on how nutrient status and cellular signaling pathways connect mTORC1 activity with ferroptosis, an iron-dependent cell death program that has been implicated in a plethora of human diseases. In-depth understanding of the principles governing the interaction between mTORC1 and cell death pathways can ultimately guide the development of novel therapies for the treatment of relevant pathological conditions.
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Affiliation(s)
- Jiajun Zhu
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China,Tsinghua-Peking Center for Life Sciences, Beijing, China,Correspondence to Jiajun Zhu:
| | - Hua Wang
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Xuejun Jiang
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY,Xuejun Jiang:
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18
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Wallace RL, Lu E, Luo X, Capaldi AP. Ait1 regulates TORC1 signaling and localization in budding yeast. eLife 2022; 11:68773. [PMID: 36047762 PMCID: PMC9499541 DOI: 10.7554/elife.68773] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 08/31/2022] [Indexed: 11/23/2022] Open
Abstract
The target of rapamycin complex I (TORC1) regulates cell growth and metabolism in eukaryotes. Previous studies have shown that nitrogen and amino acid signals activate TORC1 via the highly conserved small GTPases, Gtr1/2 (RagA/C in humans), and the GTPase activating complex SEAC/GATOR. However, it remains unclear if, and how, other proteins/pathways regulate TORC1 in simple eukaryotes like yeast. Here, we report that the previously unstudied GPCR-like protein, Ait1, binds to TORC1-Gtr1/2 in Saccharomyces cerevisiae and holds TORC1 around the vacuole during log-phase growth. Then, during amino acid starvation, Ait1 inhibits TORC1 via Gtr1/2 using a loop that resembles the RagA/C-binding domain in the human protein SLC38A9. Importantly, Ait1 is only found in the Saccharomycetaceae/codaceae, two closely related families of yeast that have lost the ancient TORC1 regulators Rheb and TSC1/2. Thus, the TORC1 circuit found in the Saccharomycetaceae/codaceae, and likely other simple eukaryotes, has undergone significant rewiring during evolution.
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Affiliation(s)
- Ryan L Wallace
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Eric Lu
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Xiangxia Luo
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Andrew P Capaldi
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
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19
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Wood TE, Westervelt KA, Yoon JM, Eshleman HD, Levy R, Burnes H, Slade DJ, Lesser CF, Goldberg MB. The Shigella Spp. Type III Effector Protein OspB Is a Cysteine Protease. mBio 2022; 13:e0127022. [PMID: 35638611 PMCID: PMC9239218 DOI: 10.1128/mbio.01270-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 05/05/2022] [Indexed: 11/20/2022] Open
Abstract
The type III secretion system is required for virulence of many pathogenic bacteria. Bacterial effector proteins delivered into target host cells by this system modulate host signaling pathways and processes in a manner that promotes infection. Here, we define the activity of the effector protein OspB of the human pathogen Shigella spp., the etiological agent of shigellosis and bacillary dysentery. Using the yeast Saccharomyces cerevisiae as a model organism, we show that OspB sensitizes cells to inhibition of TORC1, the central regulator of growth and metabolism. In silico analyses reveal that OspB bears structural homology to bacterial cysteine proteases that target mammalian cell processes, and we define a conserved cysteine-histidine catalytic dyad required for OspB function. Using yeast genetic screens, we identify a crucial role for the arginine N-degron pathway in the yeast growth inhibition phenotype and show that inositol hexakisphosphate is an OspB cofactor. We find that a yeast substrate for OspB is the TORC1 component Tco89p, proteolytic cleavage of which generates a C-terminal fragment that is targeted for degradation via the arginine N-degron pathway; processing and degradation of Tco89p is required for the OspB phenotype. In all, we demonstrate that the Shigella T3SS effector OspB is a cysteine protease and decipher its interplay with eukaryotic cell processes. IMPORTANCEShigella spp. are important human pathogens and among the leading causes of diarrheal mortality worldwide, especially in children. Virulence depends on the Shigella type III secretion system (T3SS). Definition of the roles of the bacterial effector proteins secreted by the T3SS is key to understanding Shigella pathogenesis. The effector protein OspB contributes to a range of phenotypes during infection, yet the mechanism of action is unknown. Here, we show that S. flexneri OspB possesses cysteine protease activity in both yeast and mammalian cells, and that enzymatic activity of OspB depends on a conserved cysteine-histidine catalytic dyad. We determine how its protease activity sensitizes cells to TORC1 inhibition in yeast, finding that OspB cleaves a component of yeast TORC1, and that the degradation of the C-terminal cleavage product is responsible for OspB-mediated hypersensitivity to TORC1 inhibitors. Thus, OspB is a cysteine protease that depends on a conserved cysteine-histidine catalytic dyad.
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Affiliation(s)
- Thomas E. Wood
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Kathleen A. Westervelt
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Jessica M. Yoon
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Heather D. Eshleman
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Roie Levy
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Henry Burnes
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Daniel J. Slade
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
| | - Cammie F. Lesser
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Marcia B. Goldberg
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA
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20
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Yeast cell death pathway requiring AP-3 vesicle trafficking leads to vacuole/lysosome membrane permeabilization. Cell Rep 2022; 39:110647. [PMID: 35417721 PMCID: PMC9074372 DOI: 10.1016/j.celrep.2022.110647] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 02/17/2022] [Accepted: 03/16/2022] [Indexed: 12/24/2022] Open
Abstract
Unicellular eukaryotes have been suggested as undergoing self-inflicted destruction. However, molecular details are sparse compared with the mechanisms of programmed/regulated cell death known for human cells and animal models. Here, we report a molecular cell death pathway in Saccharomyces cerevisiae leading to vacuole/lysosome membrane permeabilization. Following a transient cell death stimulus, yeast cells die slowly over several hours, consistent with an ongoing molecular dying process. A genome-wide screen for death-promoting factors identified all subunits of the AP-3 complex, a vesicle trafficking adapter known to transport and install newly synthesized proteins on the vacuole/lysosome membrane. To promote cell death, AP-3 requires its Arf1-GTPase-dependent vesicle trafficking function and the kinase Yck3, which is selectively transported to the vacuole membrane by AP-3. Video microscopy revealed a sequence of events where vacuole permeability precedes the loss of plasma membrane integrity. AP-3-dependent death appears to be conserved in the human pathogenic yeast Cryptococcus neoformans. Details about how mammalian cells die have yielded effective cancer therapies. Similarly, details about fungal cell death may explain failed responses to anti-fungal agents and inform next-generation anti-fungal strategies. Stolp et al. describe a potential mechanism of yeast cell death subversion, by inhibiting AP-3 vesicle trafficking to block vacuole/lysosome permeability.
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21
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Jamsheer K M, Jindal S, Sharma M, Awasthi P, S S, Sharma M, Mannully CT, Laxmi A. A negative feedback loop of TOR signaling balances growth and stress-response trade-offs in plants. Cell Rep 2022; 39:110631. [PMID: 35385724 DOI: 10.1016/j.celrep.2022.110631] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/26/2021] [Accepted: 03/16/2022] [Indexed: 12/20/2022] Open
Abstract
TOR kinase is a central coordinator of nutrient-dependent growth in eukaryotes. Maintaining optimal TOR signaling is critical for the normal development of organisms. In this study, we describe a negative feedback loop of TOR signaling helping in the adaptability of plants in changing environmental conditions. Using an interdisciplinary approach, we show that the plant-specific zinc finger protein FLZ8 acts as a regulator of TOR signaling in Arabidopsis. In sugar sufficiency, TOR-dependent and -independent histone modifications upregulate the expression of FLZ8. FLZ8 negatively regulates TOR signaling by promoting antagonistic SnRK1α1 signaling and bridging the interaction of SnRK1α1 with RAPTOR1B, a crucial accessory protein of TOR. This negative feedback loop moderates the TOR-growth signaling axis in the favorable condition and helps in the activation of stress signaling in unfavorable conditions, establishing its importance in the adaptability of plants.
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Affiliation(s)
- Muhammed Jamsheer K
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India.
| | - Sunita Jindal
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Mohan Sharma
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Prakhar Awasthi
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Sreejath S
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Manvi Sharma
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | | | - Ashverya Laxmi
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India.
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22
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Li J, Hochstrasser M. Selective microautophagy of proteasomes is initiated by ESCRT-0 and is promoted by proteasome ubiquitylation. J Cell Sci 2022; 135:274460. [PMID: 35099016 PMCID: PMC8919337 DOI: 10.1242/jcs.259393] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 01/20/2022] [Indexed: 01/18/2023] Open
Abstract
The proteasome is central to proteolysis by the ubiquitin-proteasome system under normal growth conditions but is itself degraded through macroautophagy under nutrient stress. A recently described AMP-activated protein kinase (AMPK)-regulated endosomal sorting complex required for transport (ESCRT)-dependent microautophagy pathway also regulates proteasome trafficking and degradation in low-glucose conditions in yeast. Aberrant proteasomes are more prone to microautophagy, suggesting the ESCRT system fine-tunes proteasome quality control under low-glucose stress. Here, we uncover additional features of the selective microautophagy of proteasomes in budding yeast. Genetic or pharmacological induction of aberrant proteasomes is associated with increased mono- or oligo-ubiquitylation of proteasome components, which appears to be recognized by ESCRT-0. AMPK controls this pathway in part by regulating the trafficking of ESCRT-0 to the vacuole surface, which also leads to degradation of the Vps27 subunit of ESCRT-0. The Rsp5 ubiquitin ligase contributes to proteasome subunit ubiquitylation, and multiple ubiquitin-binding elements in Vps27 are involved in their recognition. We propose that ESCRT-0 at the vacuole surface recognizes ubiquitylated proteasomes and initiates their microautophagic elimination during glucose depletion. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Jianhui Li
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Mark Hochstrasser
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA,Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA,Author for correspondence ()
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23
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Horvath R, Hawe N, Lam C, Mestnikov K, Eji-Lasisi M, Rohde J, Sadowski I. TORC1 signaling modulates Cdk8-dependent GAL gene expression in Saccharomyces cerevisiae. Genetics 2021; 219:6381581. [PMID: 34849833 PMCID: PMC8664586 DOI: 10.1093/genetics/iyab168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 09/29/2021] [Indexed: 11/14/2022] Open
Abstract
Cdk8 of the RNA polymerase II mediator kinase complex regulates gene expression by phosphorylating sequence-specific transcription factors. This function is conserved amongst eukaryotes, but the signals and mechanisms regulating Cdk8 activity and phosphorylation of its substrates are unknown. Full induction of the GAL genes in yeast requires phosphorylation of the transcriptional activator Gal4 by Cdk8. We used a screen to identify regulators of the Cdk8-dependent phosphorylation on Gal4, from which we identified multiple mutants with defects in TORC1 signaling. One mutant, designated gal four throttle 1 (gft1) was identified as a recessive allele of hom3, encoding aspartokinase, and mutations in hom3 caused effects typical of inhibition of TORC1, including rapamycin sensitivity and enhanced nuclear localization of the TORC1-responsive transcription factor Gat1. Mutations in hom3 also inhibit phosphorylation of Gal4 in vivo at the Cdk8-dependent site on Gal4, as did mutations of tor1, but these mutations did not affect activity of Cdk8 assayed in vitro. Disruption of cdc55, encoding a regulatory subunit of the TORC1-regulated protein phosphatase PP2A, suppressed the effect of hom3 and tor1 mutations on GAL expression, and also restored phosphorylation of Gal4 at the Cdk8-dependent site in vivo. These observations demonstrate that TORC1 signaling regulates GAL induction through the activity of PP2A/Cdc55 and suggest that Cdk8-dependent phosphorylation of Gal4 is opposed by PP2A/Cdc55 dephosphorylation. These results provide insight into how induction of transcription by a specific inducer can be modulated by global nutritional signals through regulation of Cdk8-dependent phosphorylation.
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Affiliation(s)
- Riley Horvath
- Department of Biochemistry and Molecular Biology, Molecular Epigenetics Group, LSI, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Nicole Hawe
- Department of Biochemistry and Molecular Biology, Molecular Epigenetics Group, LSI, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Cindy Lam
- Department of Biochemistry and Molecular Biology, Molecular Epigenetics Group, LSI, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Konstantin Mestnikov
- Department of Biochemistry and Molecular Biology, Molecular Epigenetics Group, LSI, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Mariam Eji-Lasisi
- Department of Biochemistry and Molecular Biology, Molecular Epigenetics Group, LSI, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - John Rohde
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Ivan Sadowski
- Department of Biochemistry and Molecular Biology, Molecular Epigenetics Group, LSI, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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24
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Novarina D, Guerra P, Milias-Argeitis A. Vacuolar Localization via the N-terminal Domain of Sch9 is Required for TORC1-dependent Phosphorylation and Downstream Signal Transduction. J Mol Biol 2021; 433:167326. [PMID: 34695378 DOI: 10.1016/j.jmb.2021.167326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/12/2021] [Accepted: 10/18/2021] [Indexed: 10/20/2022]
Abstract
The budding yeast Sch9 kinase (functional orthologue of the mammalian S6 kinase) is a major effector of the Target of Rapamycin Complex 1 (TORC1) complex in the regulation of cell growth in response to nutrient availability and stress. Sch9 is partially localized at the vacuolar surface, where it is phosphorylated by TORC1. The recruitment of Sch9 on the vacuole is mediated by direct interaction between phospholipids of the vacuolar membrane and the region of Sch9 encompassing amino acid residues 1-390, which contains a C2 domain. Since many C2 domains mediate phospholipid binding, it had been suggested that the C2 domain of Sch9 mediates its vacuolar recruitment. However, the in vivo requirement of the C2 domain for Sch9 localization had not been demonstrated, and the phenotypic consequences of Sch9 delocalization remained unknown. Here, by examining cellular localization, phosphorylation state and growth phenotypes of Sch9 truncation mutants, we show that deletion of the N-terminal domain of Sch9 (aa 1-182), but not the C2 domain (aa 183-399), impairs vacuolar localization and TORC1-dependent phosphorylation of Sch9, while causing growth defects similar to those observed in Sch9Δ cells. These defects can be reversed either via artificial tethering of the protein to the vacuole, or by introducing phosphomimetic mutations at the TORC1 target sites, suggesting that Sch9 localization on the vacuole is needed for the TORC1-dependent activation of the kinase. Our study uncovers a key role for the N-terminal domain of Sch9 and provides new mechanistic insight into the regulation of a major TORC1 signaling branch.
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Affiliation(s)
- Daniele Novarina
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands
| | - Paolo Guerra
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands
| | - Andreas Milias-Argeitis
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
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25
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Brink DP, Borgström C, Persson VC, Ofuji Osiro K, Gorwa-Grauslund MF. D-Xylose Sensing in Saccharomyces cerevisiae: Insights from D-Glucose Signaling and Native D-Xylose Utilizers. Int J Mol Sci 2021; 22:12410. [PMID: 34830296 PMCID: PMC8625115 DOI: 10.3390/ijms222212410] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 11/17/2022] Open
Abstract
Extension of the substrate range is among one of the metabolic engineering goals for microorganisms used in biotechnological processes because it enables the use of a wide range of raw materials as substrates. One of the most prominent examples is the engineering of baker's yeast Saccharomyces cerevisiae for the utilization of d-xylose, a five-carbon sugar found in high abundance in lignocellulosic biomass and a key substrate to achieve good process economy in chemical production from renewable and non-edible plant feedstocks. Despite many excellent engineering strategies that have allowed recombinant S. cerevisiae to ferment d-xylose to ethanol at high yields, the consumption rate of d-xylose is still significantly lower than that of its preferred sugar d-glucose. In mixed d-glucose/d-xylose cultivations, d-xylose is only utilized after d-glucose depletion, which leads to prolonged process times and added costs. Due to this limitation, the response on d-xylose in the native sugar signaling pathways has emerged as a promising next-level engineering target. Here we review the current status of the knowledge of the response of S. cerevisiae signaling pathways to d-xylose. To do this, we first summarize the response of the native sensing and signaling pathways in S. cerevisiae to d-glucose (the preferred sugar of the yeast). Using the d-glucose case as a point of reference, we then proceed to discuss the known signaling response to d-xylose in S. cerevisiae and current attempts of improving the response by signaling engineering using native targets and synthetic (non-native) regulatory circuits.
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Affiliation(s)
- Daniel P. Brink
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
| | - Celina Borgström
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
- BioZone Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St., Toronto, ON M5S 3E5, Canada
| | - Viktor C. Persson
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
| | - Karen Ofuji Osiro
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
- Genetics and Biotechnology Laboratory, Embrapa Agroenergy, Brasília 70770-901, DF, Brazil
| | - Marie F. Gorwa-Grauslund
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden; (C.B.); (V.C.P.); (K.O.O.)
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26
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Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress. Microorganisms 2021; 9:microorganisms9102152. [PMID: 34683473 PMCID: PMC8540245 DOI: 10.3390/microorganisms9102152] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 01/18/2023] Open
Abstract
The Cdk8 kinase module (CKM) of the multi-subunit mediator complex plays an essential role in cell fate decisions in response to different environmental cues. In the budding yeast S. cerevisiae, the CKM consists of four conserved subunits (cyclin C and its cognate cyclin-dependent kinase Cdk8, Med13, and Med12) and predominantly negatively regulates a subset of stress responsive genes (SRG’s). Derepression of these SRG’s is accomplished by disassociating the CKM from the mediator, thus allowing RNA polymerase II-directed transcription. In response to cell death stimuli, cyclin C translocates to the mitochondria where it induces mitochondrial hyper-fission and promotes regulated cell death (RCD). The nuclear release of cyclin C requires Med13 destruction by the ubiquitin-proteasome system (UPS). In contrast, to protect the cell from RCD following SRG induction induced by nutrient deprivation, cyclin C is rapidly destroyed by the UPS before it reaches the cytoplasm. This enables a survival response by two mechanisms: increased ATP production by retaining reticular mitochondrial morphology and relieving CKM-mediated repression on autophagy genes. Intriguingly, nitrogen starvation also stimulates Med13 destruction but through a different mechanism. Rather than destruction via the UPS, Med13 proteolysis occurs in the vacuole (yeast lysosome) via a newly identified Snx4-assisted autophagy pathway. Taken together, these findings reveal that the CKM regulates cell fate decisions by both transcriptional and non-transcriptional mechanisms, placing it at a convergence point between cell death and cell survival pathways.
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27
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Hatakeyama R. Pib2 as an Emerging Master Regulator of Yeast TORC1. Biomolecules 2021; 11:biom11101489. [PMID: 34680122 PMCID: PMC8533233 DOI: 10.3390/biom11101489] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/05/2021] [Accepted: 10/07/2021] [Indexed: 12/18/2022] Open
Abstract
Cell growth is dynamically regulated in response to external cues such as nutrient availability, growth factor signals, and stresses. Central to this adaptation process is the Target of Rapamycin Complex 1 (TORC1), an evolutionarily conserved kinase complex that fine-tunes an enormous number of cellular events. How upstream signals are sensed and transmitted to TORC1 has been intensively studied in major model organisms including the budding yeast Saccharomyces cerevisiae. This field recently saw a breakthrough: the identification of yeast phosphatidylInositol(3)-phosphate binding protein 2 (Pib2) protein as a critical regulator of TORC1. Although the study of Pib2 is still in its early days, multiple groups have provided important mechanistic insights on how Pib2 relays nutrient signals to TORC1. There remain, on the other hand, significant gaps in our knowledge and mysteries that warrant further investigations. This is the first dedicated review on Pib2 that summarizes major findings and outstanding questions around this emerging key player in cell growth regulation.
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Affiliation(s)
- Riko Hatakeyama
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
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28
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Trefts E, Shaw RJ. AMPK: restoring metabolic homeostasis over space and time. Mol Cell 2021; 81:3677-3690. [PMID: 34547233 DOI: 10.1016/j.molcel.2021.08.015] [Citation(s) in RCA: 168] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 08/09/2021] [Accepted: 08/11/2021] [Indexed: 12/25/2022]
Abstract
The evolution of AMPK and its homologs enabled exquisite responsivity and control of cellular energetic homeostasis. Recent work has been critical in establishing the mechanisms that determine AMPK activity, novel targets of AMPK action, and the distribution of AMPK-mediated control networks across the cellular landscape. The role of AMPK as a hub of metabolic control has led to intense interest in pharmacologic activation as a therapeutic avenue for a number of disease states, including obesity, diabetes, and cancer. As such, critical work on the compartmentalization of AMPK, its downstream targets, and the systems it influences has progressed in recent years. The variegated distribution of AMPK-mediated control of metabolic homeostasis has revealed key insights into AMPK in normal biology and future directions for AMPK-based therapeutic strategies.
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Affiliation(s)
- Elijah Trefts
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Reuben J Shaw
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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29
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Zhou X, Li J, Tang N, Xie H, Fan X, Chen H, Tang M, Xie X. Genome-Wide Analysis of Nutrient Signaling Pathways Conserved in Arbuscular Mycorrhizal Fungi. Microorganisms 2021; 9:1557. [PMID: 34442636 PMCID: PMC8401276 DOI: 10.3390/microorganisms9081557] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/13/2021] [Accepted: 07/16/2021] [Indexed: 01/03/2023] Open
Abstract
Arbuscular mycorrhizal (AM) fungi form a mutualistic symbiosis with a majority of terrestrial vascular plants. To achieve an efficient nutrient trade with their hosts, AM fungi sense external and internal nutrients, and integrate different hierarchic regulations to optimize nutrient acquisition and homeostasis during mycorrhization. However, the underlying molecular networks in AM fungi orchestrating the nutrient sensing and signaling remain elusive. Based on homology search, we here found that at least 72 gene components involved in four nutrient sensing and signaling pathways, including cAMP-dependent protein kinase A (cAMP-PKA), sucrose non-fermenting 1 (SNF1) protein kinase, target of rapamycin kinase (TOR) and phosphate (PHO) signaling cascades, are well conserved in AM fungi. Based on the knowledge known in model yeast and filamentous fungi, we outlined the possible gene networks functioning in AM fungi. These pathways may regulate the expression of downstream genes involved in nutrient transport, lipid metabolism, trehalase activity, stress resistance and autophagy. The RNA-seq analysis and qRT-PCR results of some core genes further indicate that these pathways may play important roles in spore germination, appressorium formation, arbuscule longevity and sporulation of AM fungi. We hope to inspire further studies on the roles of these candidate genes involved in these nutrient sensing and signaling pathways in AM fungi and AM symbiosis.
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Affiliation(s)
- Xiaoqin Zhou
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Jiangyong Li
- Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China;
| | - Nianwu Tang
- UMR Interactions Arbres/Microorganismes, Centre INRA-Grand Est-Nancy, 54280 Champenoux, France;
| | - Hongyun Xie
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Xiaoning Fan
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Hui Chen
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Ming Tang
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
| | - Xianan Xie
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (X.Z.); (H.X.); (X.F.); (H.C.)
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30
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Kumar A. The Complex Genetic Basis and Multilayered Regulatory Control of Yeast Pseudohyphal Growth. Annu Rev Genet 2021; 55:1-21. [PMID: 34280314 DOI: 10.1146/annurev-genet-071719-020249] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Eukaryotic cells are exquisitely responsive to external and internal cues, achieving precise control of seemingly diverse growth processes through a complex interplay of regulatory mechanisms. The budding yeast Saccharomyces cerevisiae provides a fascinating model of cell growth in its stress-responsive transition from planktonic single cells to a filamentous pseudohyphal growth form. During pseudohyphal growth, yeast cells undergo changes in morphology, polarity, and adhesion to form extended and invasive multicellular filaments. This pseudohyphal transition has been studied extensively as a model of conserved signaling pathways regulating cell growth and for its relevance in understanding the pathogenicity of the related opportunistic fungus Candida albicans, wherein filamentous growth is required for virulence. This review highlights the broad gene set enabling yeast pseudohyphal growth, signaling pathways that regulate this process, the role and regulation of proteins conferring cell adhesion, and interesting regulatory mechanisms enabling the pseudohyphal transition. Expected final online publication date for the Annual Review of Genetics, Volume 55 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Anuj Kumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA;
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31
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Alfatah M, Wong JH, Krishnan VG, Lee YC, Sin QF, Goh CJH, Kong KW, Lee WT, Lewis J, Hoon S, Arumugam P. TORC1 regulates the transcriptional response to glucose and developmental cycle via the Tap42-Sit4-Rrd1/2 pathway in Saccharomyces cerevisiae. BMC Biol 2021; 19:95. [PMID: 33957926 PMCID: PMC8103650 DOI: 10.1186/s12915-021-01030-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 04/18/2021] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Target of Rapamycin Complex 1 (TORC1) is a highly conserved eukaryotic protein complex that couples the presence of growth factors and nutrients in the environment with cellular proliferation. TORC1 is primarily implicated in linking amino acid levels with cellular growth in yeast and mammals. Although glucose deprivation has been shown to cause TORC1 inactivation in yeast, the precise role of TORC1 in glucose signaling and the underlying mechanisms remain unclear. RESULTS We demonstrate that the presence of glucose in the growth medium is both necessary and sufficient for TORC1 activation. TORC1 activity increases upon addition of glucose to yeast cells growing in a non-fermentable carbon source. Conversely, shifting yeast cells from glucose to a non-fermentable carbon source reduces TORC1 activity. Analysis of transcriptomic data revealed that glucose and TORC1 co-regulate about 27% (1668/6004) of yeast genes. We demonstrate that TORC1 orchestrates the expression of glucose-responsive genes mainly via the Tap42-Sit4-Rrd1/2 pathway. To confirm TORC1's function in glucose signaling, we tested its role in spore germination, a glucose-dependent developmental state transition in yeast. TORC1 regulates the glucose-responsive genes during spore germination and inhibition of TORC1 blocks spore germination. CONCLUSIONS Our studies indicate that a regulatory loop that involves activation of TORC1 by glucose and regulation of glucose-responsive genes by TORC1, mediates nutritional control of growth and development in yeast.
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Affiliation(s)
- Mohammad Alfatah
- Bioinformatics Institute, 30 Biopolis Street, Singapore, 138671, Singapore
| | - Jin Huei Wong
- Bioinformatics Institute, 30 Biopolis Street, Singapore, 138671, Singapore
| | | | - Yong Cheow Lee
- Bioinformatics Institute, 30 Biopolis Street, Singapore, 138671, Singapore
| | - Quan Feng Sin
- Bioinformatics Institute, 30 Biopolis Street, Singapore, 138671, Singapore
| | | | - Kiat Whye Kong
- Molecular Engineering Lab, 61 Biopolis Drive, Singapore, 138673, Singapore
| | - Wei Ting Lee
- Bioinformatics Institute, 30 Biopolis Street, Singapore, 138671, Singapore
| | - Jacqueline Lewis
- Bioinformatics Institute, 30 Biopolis Street, Singapore, 138671, Singapore
| | - Shawn Hoon
- Molecular Engineering Lab, 61 Biopolis Drive, Singapore, 138673, Singapore
| | - Prakash Arumugam
- Bioinformatics Institute, 30 Biopolis Street, Singapore, 138671, Singapore. .,Singapore Institute for Food and Biotechnology Innovation, 31 Biopolis Way, #01-02 Nanos, Singapore, 138669, Singapore. .,School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore.
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32
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Wallace RL, Lu E, Sullivan A, Hallett JEH, Capaldi AP. Analysis of TORC1-body Formation in Budding Yeast. Bio Protoc 2021; 11:e3975. [PMID: 33889669 DOI: 10.21769/bioprotoc.3975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 02/04/2021] [Accepted: 02/23/2021] [Indexed: 11/02/2022] Open
Abstract
The Target of Rapamycin kinase Complex I (TORC1) is the master regulator of cell growth and metabolism in eukaryotes. In the presence of pro-growth hormones and abundant nutrients, TORC1 is active and drives protein, lipid, and nucleotide synthesis by phosphorylating a wide range of proteins. In contrast, when nitrogen and/or glucose levels fall, TORC1 is inhibited, causing the cell to switch from anabolic to catabolic metabolism, and eventually enter a quiescent state. In the budding yeast Saccharomyces cerevisiae, TORC1 inhibition triggers the movement of TORC1 from its position around the vacuole to a single focus/body on the edge of the vacuolar membrane. This relocalization depends on the activity of numerous key TORC1 regulators and thus analysis of TORC1 localization can be used to follow signaling through the TORC1 pathway. Here we provide a detailed protocol for measuring TORC1 (specifically, Kog1-YFP) relocalization/signaling using fluorescence microscopy. Emphasis is placed on procedures that ensure: (1) TORC1-bodies are identified (and counted) correctly despite their relatively low fluorescence and the accumulation of autofluorescent foci during glucose and nitrogen starvation; (2) Cells are kept in log-phase growth at the start of each experiment so that the dynamics of TORC1-body formation are monitored correctly; (3) The appropriate fluorescent tags are used to avoid examining mislocalized TORC1.
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Affiliation(s)
- Ryan L Wallace
- Dept of Molecular and Cellular Biology, University of Arizona, Tucson AZ, USA
| | - Eric Lu
- Dept of Molecular and Cellular Biology, University of Arizona, Tucson AZ, USA
| | - Arron Sullivan
- Dept of Molecular and Cellular Biology, University of Arizona, Tucson AZ, USA
| | | | - Andrew P Capaldi
- Dept of Molecular and Cellular Biology, University of Arizona, Tucson AZ, USA
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33
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Rashida Z, Srinivasan R, Cyanam M, Laxman S. Kog1/Raptor mediates metabolic rewiring during nutrient limitation by controlling SNF1/AMPK activity. SCIENCE ADVANCES 2021; 7:eabe5544. [PMID: 33853774 PMCID: PMC8046376 DOI: 10.1126/sciadv.abe5544] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 02/26/2021] [Indexed: 05/04/2023]
Abstract
In changing environments, cells modulate resource budgeting through distinct metabolic routes to control growth. Accordingly, the TORC1 and SNF1/AMPK pathways operate contrastingly in nutrient replete or limited environments to maintain homeostasis. The functions of TORC1 under glucose and amino acid limitation are relatively unknown. We identified a modified form of the yeast TORC1 component Kog1/Raptor, which exhibits delayed growth exclusively during glucose and amino acid limitations. Using this, we found a necessary function for Kog1 in these conditions where TORC1 kinase activity is undetectable. Metabolic flux and transcriptome analysis revealed that Kog1 controls SNF1-dependent carbon flux apportioning between glutamate/amino acid biosynthesis and gluconeogenesis. Kog1 regulates SNF1/AMPK activity and outputs and mediates a rapamycin-independent activation of the SNF1 targets Mig1 and Cat8. This enables effective glucose derepression, gluconeogenesis activation, and carbon allocation through different pathways. Therefore, Kog1 centrally regulates metabolic homeostasis and carbon utilization during nutrient limitation by managing SNF1 activity.
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Affiliation(s)
- Zeenat Rashida
- Institute for Stem Cell Science and Regenerative Medicine (inStem), GKVK Post, Bellary Road, Bangalore 560065, India
- Manipal Academy of Higher Education, Manipal 576104, India
| | - Rajalakshmi Srinivasan
- Institute for Stem Cell Science and Regenerative Medicine (inStem), GKVK Post, Bellary Road, Bangalore 560065, India
| | - Meghana Cyanam
- Institute for Stem Cell Science and Regenerative Medicine (inStem), GKVK Post, Bellary Road, Bangalore 560065, India
| | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine (inStem), GKVK Post, Bellary Road, Bangalore 560065, India.
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34
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Saad S, Jarosz DF. Protein self-assembly: A new frontier in cell signaling. Curr Opin Cell Biol 2021; 69:62-69. [PMID: 33493989 PMCID: PMC8058241 DOI: 10.1016/j.ceb.2020.12.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 12/20/2022]
Abstract
Long viewed as paradigm-shifting, but rare, prions have recently been discovered in all domains of life. Protein sequences that can drive this form of self-assembly are strikingly common in eukaryotic proteomes, where they are enriched in proteins involved in information flow and signal transduction. Although prions were thought to be a consequence of random errors in protein folding, recent studies suggest that prion formation can be a controlled process initiated by defined cellular signals. Many are present in normal biological contexts, yet are invisible to most technologies used to interrogate the proteome. Here, we review mechanisms by which protein self-assembly can create a stable record of past stimuli, altering adaptive responses, and how prion behavior is controlled by signaling processes. We touch on the diverse implications that this has for normal biological function and regulation, ranging from drug resistance in fungi to the innate immune response in humans. Finally, we discuss the potential for prion domains in transcription factors and RNA-binding proteins to orchestrate heritable gene expression changes in response to transient signals, such as during development.
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Affiliation(s)
- Shady Saad
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Daniel F Jarosz
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA; Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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35
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Simpson-Lavy K, Kupiec M. Noise buffering by biomolecular condensates in glucose sensing. Curr Opin Cell Biol 2020; 69:1-6. [PMID: 33388622 DOI: 10.1016/j.ceb.2020.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/26/2020] [Accepted: 12/01/2020] [Indexed: 02/05/2023]
Abstract
Many cellular processes involve buffering mechanisms against noise to enhance state stability. Such processes include the cell cycle and the switch between respiration and fermentation. In recent years, protein aggregation/condensation has emerged as an important regulatory mechanism. In this article, we examine the regulation of Std1, an activator of the Snf1/AMPK kinase, by sequestration into foci of liquid drops, and how foci of metabolic signaling and enzymatic proteins are regulated by chaperones, anti-aggregases and by phosphorylation.
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Affiliation(s)
- Kobi Simpson-Lavy
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Ramat Aviv, 69978, Israel
| | - Martin Kupiec
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Ramat Aviv, 69978, Israel.
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36
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Barba-Aliaga M, Villarroel-Vicente C, Stanciu A, Corman A, Martínez-Pastor MT, Alepuz P. Yeast Translation Elongation Factor eIF5A Expression Is Regulated by Nutrient Availability through Different Signalling Pathways. Int J Mol Sci 2020; 22:E219. [PMID: 33379337 PMCID: PMC7794953 DOI: 10.3390/ijms22010219] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/17/2020] [Accepted: 12/24/2020] [Indexed: 12/15/2022] Open
Abstract
Translation elongation factor eIF5A binds to ribosomes to promote peptide bonds between problematic amino acids for the reaction like prolines. eIF5A is highly conserved and essential in eukaryotes, which usually contain two similar but differentially expressed paralogue genes. The human eIF5A-1 isoform is abundant and implicated in some cancer types; the eIF5A-2 isoform is absent in most cells but becomes overexpressed in many metastatic cancers. Several reports have connected eIF5A and mitochondria because it co-purifies with the organelle or its inhibition reduces respiration and mitochondrial enzyme levels. However, the mechanisms of eIF5A mitochondrial function, and whether eIF5A expression is regulated by the mitochondrial metabolism, are unknown. We analysed the expression of yeast eIF5A isoforms Tif51A and Tif51B under several metabolic conditions and in mutants. The depletion of Tif51A, but not Tif51B, compromised yeast growth under respiration and reduced oxygen consumption. Tif51A expression followed dual positive regulation: by high glucose through TORC1 signalling, like other translation factors, to promote growth and by low glucose or non-fermentative carbon sources through Snf1 and heme-dependent transcription factor Hap1 to promote respiration. Upon iron depletion, Tif51A was down-regulated and Tif51B up-regulated. Both were Hap1-dependent. Our results demonstrate eIF5A expression regulation by cellular metabolic status.
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Affiliation(s)
- Marina Barba-Aliaga
- Instituto Biotecmed, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain; (M.B.-A.); (C.V.-V.); (A.S.); (A.C.)
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain;
| | - Carlos Villarroel-Vicente
- Instituto Biotecmed, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain; (M.B.-A.); (C.V.-V.); (A.S.); (A.C.)
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain;
| | - Alice Stanciu
- Instituto Biotecmed, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain; (M.B.-A.); (C.V.-V.); (A.S.); (A.C.)
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain;
| | - Alba Corman
- Instituto Biotecmed, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain; (M.B.-A.); (C.V.-V.); (A.S.); (A.C.)
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain;
| | - María Teresa Martínez-Pastor
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain;
| | - Paula Alepuz
- Instituto Biotecmed, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain; (M.B.-A.); (C.V.-V.); (A.S.); (A.C.)
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, C/Dr. Moliner 50, E46100 Burjassot, Spain;
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Montrose K, López Cabezas RM, Paukštytė J, Saarikangas J. Winter is coming: Regulation of cellular metabolism by enzyme polymerization in dormancy and disease. Exp Cell Res 2020; 397:112383. [PMID: 33212148 DOI: 10.1016/j.yexcr.2020.112383] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 11/12/2020] [Accepted: 11/14/2020] [Indexed: 12/20/2022]
Abstract
Metabolism feeds growth. Accordingly, metabolism is regulated by nutrient-sensing pathways that converge growth promoting signals into biosynthesis by regulating the activity of metabolic enzymes. When the environment does not support growth, organisms invest in survival. For cells, this entails transitioning into a dormant, quiescent state (G0). In dormancy, the activity of biosynthetic pathways is dampened, and catabolic metabolism and stress tolerance pathways are activated. Recent work in yeast has demonstrated that dormancy is associated with alterations in the physicochemical properties of the cytoplasm, including changes in pH, viscosity and macromolecular crowding. Accompanying these changes, numerous metabolic enzymes transition from soluble to polymerized assemblies. These large-scale self-assemblies are dynamic and depolymerize when cells resume growth. Here we review how enzyme polymerization enables metabolic plasticity by tuning carbohydrate, nucleic acid, amino acid and lipid metabolic pathways, with particular focus on its potential adaptive value in cellular dormancy.
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Affiliation(s)
- Kristopher Montrose
- Helsinki Institute of Life Science, HiLIFE, University of Helsinki, Finland; Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Rosa María López Cabezas
- Helsinki Institute of Life Science, HiLIFE, University of Helsinki, Finland; Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Jurgita Paukštytė
- Helsinki Institute of Life Science, HiLIFE, University of Helsinki, Finland; Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Juha Saarikangas
- Helsinki Institute of Life Science, HiLIFE, University of Helsinki, Finland; Research Programme in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland; Neuroscience Center, University of Helsinki, Finland.
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Mugume Y, Kazibwe Z, Bassham DC. Target of Rapamycin in Control of Autophagy: Puppet Master and Signal Integrator. Int J Mol Sci 2020; 21:ijms21218259. [PMID: 33158137 PMCID: PMC7672647 DOI: 10.3390/ijms21218259] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/01/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023] Open
Abstract
The target of rapamycin (TOR) is an evolutionarily-conserved serine/threonine kinase that senses and integrates signals from the environment to coordinate developmental and metabolic processes. TOR senses nutrients, hormones, metabolites, and stress signals to promote cell and organ growth when conditions are favorable. However, TOR is inhibited when conditions are unfavorable, promoting catabolic processes such as autophagy. Autophagy is a macromolecular degradation pathway by which cells degrade and recycle cytoplasmic materials. TOR negatively regulates autophagy through phosphorylation of ATG13, preventing activation of the autophagy-initiating ATG1-ATG13 kinase complex. Here we review TOR complex composition and function in photosynthetic and non-photosynthetic organisms. We also review recent developments in the identification of upstream TOR activators and downstream effectors of TOR. Finally, we discuss recent developments in our understanding of the regulation of autophagy by TOR in photosynthetic organisms.
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Hu Z, Raucci S, Jaquenoud M, Hatakeyama R, Stumpe M, Rohr R, Reggiori F, De Virgilio C, Dengjel J. Multilayered Control of Protein Turnover by TORC1 and Atg1. Cell Rep 2020; 28:3486-3496.e6. [PMID: 31553916 DOI: 10.1016/j.celrep.2019.08.069] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/19/2019] [Accepted: 08/22/2019] [Indexed: 12/13/2022] Open
Abstract
The target of rapamycin complex 1 (TORC1) is a master regulator of cell homeostasis, which promotes anabolic reactions and synchronously inhibits catabolic processes such as autophagy-mediated protein degradation. Its prime autophagy target is Atg13, a subunit of the Atg1 kinase complex that acts as the gatekeeper of canonical autophagy. To study whether the activities of TORC1 and Atg1 are coupled through additional, more intricate control mechanisms than simply this linear pathway, we analyzed the epistatic relationship between TORC1 and Atg1 by using quantitative phosphoproteomics. Our in vivo data, combined with targeted in vitro TORC1 and Atg1 kinase assays, not only uncover numerous TORC1 and Atg1 effectors, but also suggest distinct bi-directional regulatory feedback loops and characterize Atg29 as a commonly regulated downstream target of both TORC1 and Atg1. Thus, an exquisitely multilayered regulatory network appears to coordinate TORC1 and Atg1 activities to robustly tune autophagy in response to nutritional cues.
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Affiliation(s)
- Zehan Hu
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Serena Raucci
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Malika Jaquenoud
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Riko Hatakeyama
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Michael Stumpe
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Rudolf Rohr
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells & Systems, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, the Netherlands
| | | | - Jörn Dengjel
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland.
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Chen H, Miller PW, Johnson DL, Laribee RN. The Ccr4-Not complex regulates TORC1 signaling and mitochondrial metabolism by promoting vacuole V-ATPase activity. PLoS Genet 2020; 16:e1009046. [PMID: 33064727 PMCID: PMC7592917 DOI: 10.1371/journal.pgen.1009046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 10/28/2020] [Accepted: 08/12/2020] [Indexed: 01/30/2023] Open
Abstract
The Ccr4-Not complex functions as an effector of multiple signaling pathways that control gene transcription and mRNA turnover. Consequently, Ccr4-Not contributes to a diverse array of processes, which includes a significant role in cell metabolism. Yet a mechanistic understanding of how it contributes to metabolism is lacking. Herein, we provide evidence that Ccr4-Not activates nutrient signaling through the essential target of rapamycin complex 1 (TORC1) pathway. Ccr4-Not disruption reduces global TORC1 signaling, and it also upregulates expression of the cell wall integrity (CWI) pathway terminal kinase Mpk1. Although CWI signaling represses TORC1 signaling, we find that Ccr4-Not loss inhibits TORC1 independently of CWI activation. Instead, we demonstrate that Ccr4-Not promotes the function of the vacuole V-ATPase, which interacts with the Gtr1 GTPase-containing EGO complex to stimulate TORC1 in response to nutrient sufficiency. Bypassing the V-ATPase requirement in TORC1 activation using a constitutively active Gtr1 mutant fully restores TORC1 signaling in Ccr4-Not deficient cells. Transcriptome analysis and functional studies revealed that loss of the Ccr4 subunit activates the TORC1 repressed retrograde signaling pathway to upregulate mitochondrial activity. Blocking this mitochondrial upregulation in Ccr4-Not deficient cells further represses TORC1 signaling, and it causes synergistic deficiencies in mitochondrial-dependent metabolism. These data support a model whereby Ccr4-Not loss impairs V-ATPase dependent TORC1 activation that forces cells to enhance mitochondrial metabolism to sustain a minimal level of TORC1 signaling necessary for cell growth and proliferation. Therefore, Ccr4-Not plays an integral role in nutrient signaling and cell metabolism by promoting V-ATPase dependent TORC1 activation.
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Affiliation(s)
- Hongfeng Chen
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - P. Winston Miller
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - Daniel L. Johnson
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
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41
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Uemura S, Mochizuki T, Amemiya K, Kurosaka G, Yazawa M, Nakamoto K, Ishikawa Y, Izawa S, Abe F. Amino acid homeostatic control by TORC1 in Saccharomyces cerevisiae under high hydrostatic pressure. J Cell Sci 2020; 133:jcs245555. [PMID: 32801125 DOI: 10.1242/jcs.245555] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 08/05/2020] [Indexed: 12/30/2022] Open
Abstract
Mechanical stresses, including high hydrostatic pressure, elicit diverse physiological effects on organisms. Gtr1, Gtr2, Ego1 (also known as Meh1) and Ego3 (also known as Slm4), central regulators of the TOR complex 1 (TORC1) nutrient signaling pathway, are required for the growth of Saccharomyces cerevisiae cells under high pressure. Here, we showed that a pressure of 25 MPa (∼250 kg/cm2) stimulates TORC1 to promote phosphorylation of Sch9, which depends on the EGO complex (EGOC) and Pib2. Incubation of cells at this pressure aberrantly increased glutamine and alanine levels in the ego1Δ, gtr1Δ, tor1Δ and pib2Δ mutants, whereas the polysome profiles were unaffected. Moreover, we found that glutamine levels were reduced by combined deletions of EGO1, GTR1, TOR1 and PIB2 with GLN3 These results suggest that high pressure leads to the intracellular accumulation of amino acids. Subsequently, Pib2 loaded with glutamine stimulates the EGOC-TORC1 complex to inactivate Gln3, downregulating glutamine synthesis. Our findings illustrate the regulatory circuit that maintains intracellular amino acid homeostasis and suggest critical roles for the EGOC-TORC1 and Pib2-TORC1 complexes in the growth of yeast under high hydrostatic pressure.
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Affiliation(s)
- Satoshi Uemura
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
- Division of Medical Biochemistry, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, 1-15-1, Fukumuro, Miyagino-ku, Sendai, Miyagi 983-8536, Japan
| | - Takahiro Mochizuki
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Kengo Amemiya
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Goyu Kurosaka
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Miho Yazawa
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Keiko Nakamoto
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Yu Ishikawa
- Laboratory of Microbial Technology, Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - Shingo Izawa
- Laboratory of Microbial Technology, Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - Fumiyoshi Abe
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
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42
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Hijazi I, Knupp J, Chang A. Retrograde signaling mediates an adaptive survival response to endoplasmic reticulum stress in Saccharomyces cerevisiae. J Cell Sci 2020; 133:jcs.241539. [PMID: 32005698 DOI: 10.1242/jcs.241539] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 01/23/2020] [Indexed: 12/11/2022] Open
Abstract
One major cause of endoplasmic reticulum (ER) stress is homeostatic imbalance between biosynthetic protein folding and protein folding capacity. Cells utilize mechanisms such as the unfolded protein response (UPR) to cope with ER stress. Nevertheless, when ER stress is prolonged or severe, cell death may occur, accompanied by production of mitochondrial reactive oxygen species (ROS). Using a yeast model (Saccharomyces cerevisiae), we describe an innate, adaptive response to ER stress to increase select mitochondrial proteins, O2 consumption and cell survival. The mitochondrial response allows cells to resist additional ER stress. The ER stress-induced mitochondrial response is mediated by activation of retrograde (RTG) signaling to enhance anapleurotic reactions of the tricarboxylic acid cycle. Mitochondrial response to ER stress is accompanied by inactivation of the conserved TORC1 pathway, and activation of Snf1/AMPK, the conserved energy sensor and regulator of metabolism. Our results provide new insight into the role of respiration in cell survival in the face of ER stress, and should help in developing therapeutic strategies to limit cell death in disorders linked to ER stress.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Imadeddin Hijazi
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 1105 N University, Ann Arbor, MI 48109, USA
| | - Jeffrey Knupp
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 1105 N University, Ann Arbor, MI 48109, USA
| | - Amy Chang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 1105 N University, Ann Arbor, MI 48109, USA
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González A, Hall MN, Lin SC, Hardie DG. AMPK and TOR: The Yin and Yang of Cellular Nutrient Sensing and Growth Control. Cell Metab 2020; 31:472-492. [PMID: 32130880 DOI: 10.1016/j.cmet.2020.01.015] [Citation(s) in RCA: 409] [Impact Index Per Article: 102.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The AMPK (AMP-activated protein kinase) and TOR (target-of-rapamycin) pathways are interlinked, opposing signaling pathways involved in sensing availability of nutrients and energy and regulation of cell growth. AMPK (Yin, or the "dark side") is switched on by lack of energy or nutrients and inhibits cell growth, while TOR (Yang, or the "bright side") is switched on by nutrient availability and promotes cell growth. Genes encoding the AMPK and TOR complexes are found in almost all eukaryotes, suggesting that these pathways arose very early during eukaryotic evolution. During the development of multicellularity, an additional tier of cell-extrinsic growth control arose that is mediated by growth factors, but these often act by modulating nutrient uptake so that AMPK and TOR remain the underlying regulators of cellular growth control. In this review, we discuss the evolution, structure, and regulation of the AMPK and TOR pathways and the complex mechanisms by which they interact.
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Affiliation(s)
- Asier González
- Biozentrum, University of Basel, CH4056 Basel, Switzerland
| | - Michael N Hall
- Biozentrum, University of Basel, CH4056 Basel, Switzerland
| | - Sheng-Cai Lin
- School of Life Sciences, Xiamen University, Xiamen, 361102 Fujian, China
| | - D Grahame Hardie
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK.
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44
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Mechanisms of Autophagy in Metabolic Stress Response. J Mol Biol 2020; 432:28-52. [DOI: 10.1016/j.jmb.2019.09.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/06/2019] [Accepted: 09/06/2019] [Indexed: 01/17/2023]
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45
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Umekawa M, Shiraishi D, Fuwa M, Sawaguchi K, Mashima Y, Katayama T, Karita S. Mitotic cyclin Clb4 is required for the intracellular adaptation to glucose starvation inSaccharomyces cerevisiae. FEBS Lett 2019; 594:1329-1338. [DOI: 10.1002/1873-3468.13722] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/08/2019] [Accepted: 12/09/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Midori Umekawa
- Graduate School of Bioresources Mie University Tsu Japan
| | | | - Marin Fuwa
- Faculty of Bioresources Mie University Tsu Japan
| | | | | | | | - Shuichi Karita
- Graduate School of Bioresources Mie University Tsu Japan
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46
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Brito AS, Soto Diaz S, Van Vooren P, Godard P, Marini AM, Boeckstaens M. Pib2-Dependent Feedback Control of the TORC1 Signaling Network by the Npr1 Kinase. iScience 2019; 20:415-433. [PMID: 31622882 PMCID: PMC6817644 DOI: 10.1016/j.isci.2019.09.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 05/10/2019] [Accepted: 09/13/2019] [Indexed: 01/21/2023] Open
Abstract
To adjust cell growth and metabolism according to environmental conditions, the conserved TORC1 signaling network controls autophagy, protein synthesis, and turnover. Here, we dissected the signals controlling phosphorylation and activity of the TORC1-effector kinase Npr1, involved in tuning the plasma membrane permeability to nitrogen sources. By evaluating a role of pH as a signal, we show that, although a transient cytosolic acidification accompanies nitrogen source entry and is correlated to a rapid TORC1-dependent phosphorylation of Npr1, a pH drop is not a prerequisite for TORC1 activation. We show that the Gtr1/Gtr2 and Pib2 regulators of TORC1 both independently and differently contribute to regulate Npr1 phosphorylation and activity. Finally, our data reveal that Npr1 mediates nitrogen-dependent phosphorylation of Pib2, as well as a Pib2-dependent inhibition of TORC1. This work highlights a feedback control loop likely enabling efficient downregulation and faster re-activation of TORC1 in response to a novel stimulating signal.
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Affiliation(s)
- Ana Sofia Brito
- Laboratory of Biology of Membrane Transport, IBMM, Université Libre de Bruxelles, rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium
| | - Silvia Soto Diaz
- Laboratory of Biology of Membrane Transport, IBMM, Université Libre de Bruxelles, rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium
| | - Pascale Van Vooren
- Laboratory of Biology of Membrane Transport, IBMM, Université Libre de Bruxelles, rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium
| | - Patrice Godard
- UCB Pharma, Chemin du Foriest, 1420 Braine-l'Alleud, Belgium
| | - Anna Maria Marini
- Laboratory of Biology of Membrane Transport, IBMM, Université Libre de Bruxelles, rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium
| | - Mélanie Boeckstaens
- Laboratory of Biology of Membrane Transport, IBMM, Université Libre de Bruxelles, rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium.
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47
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Cell organelles and yeast longevity: an intertwined regulation. Curr Genet 2019; 66:15-41. [PMID: 31535186 DOI: 10.1007/s00294-019-01035-0] [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: 06/03/2019] [Revised: 09/12/2019] [Accepted: 09/12/2019] [Indexed: 12/16/2022]
Abstract
Organelles are dynamic structures of a eukaryotic cell that compartmentalize various essential functions and regulate optimum functioning. On the other hand, ageing is an inevitable phenomenon that leads to irreversible cellular damage and affects optimum functioning of cells. Recent research shows compelling evidence that connects organelle dysfunction to ageing-related diseases/disorders. Studies in several model systems including yeast have led to seminal contributions to the field of ageing in uncovering novel pathways, proteins and their functions, identification of pro- and anti-ageing factors and so on. In this review, we present a comprehensive overview of findings that highlight the role of organelles in ageing and ageing-associated functions/pathways in yeast.
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48
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Kunkel J, Luo X, Capaldi AP. Integrated TORC1 and PKA signaling control the temporal activation of glucose-induced gene expression in yeast. Nat Commun 2019; 10:3558. [PMID: 31395866 PMCID: PMC6687784 DOI: 10.1038/s41467-019-11540-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/19/2019] [Indexed: 01/04/2023] Open
Abstract
The growth rate of a yeast cell is controlled by the target of rapamycin kinase complex I (TORC1) and cAMP-dependent protein kinase (PKA) pathways. To determine how TORC1 and PKA cooperate to regulate cell growth, we performed temporal analysis of gene expression in yeast switched from a non-fermentable substrate, to glucose, in the presence and absence of TORC1 and PKA inhibitors. Quantitative analysis of these data reveals that PKA drives the expression of key cell growth genes during transitions into, and out of, the rapid growth state in glucose, while TORC1 is important for the steady-state expression of the same genes. This circuit design may enable yeast to set an exact growth rate based on the abundance of internal metabolites such as amino acids, via TORC1, but also adapt rapidly to changes in external nutrients, such as glucose, via PKA.
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Affiliation(s)
- Joseph Kunkel
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721-0206, USA
| | - Xiangxia Luo
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721-0206, USA
| | - Andrew P Capaldi
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721-0206, USA.
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49
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Babst M. Eisosomes at the intersection of TORC1 and TORC2 regulation. Traffic 2019; 20:543-551. [PMID: 31038844 DOI: 10.1111/tra.12651] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/24/2019] [Accepted: 04/26/2019] [Indexed: 12/14/2022]
Abstract
Eisosomes are furrows in the yeast plasma membrane that form a membrane domain with distinct lipid and protein composition. Recent studies highlighted the importance of this domain for the regulation of proton-nutrient symporters. The amino acids and other nutrients, which these transporters deliver to the cytoplasm not only feed into metabolic pathways but also activate the metabolic regulator TORC1. Eisosomes have also been shown to harbor the membrane stress sensors Slm1 and Slm2. Membrane tension caused by hypoosmotic shock results in the redistribution of Slm1/2 from eisosomes to TORC2 which in turn regulates lipid synthesis. Therefore, eisosomes function upstream of both TORC1 and TORC2 regulation.
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Affiliation(s)
- Markus Babst
- Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah
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Margalha L, Confraria A, Baena-González E. SnRK1 and TOR: modulating growth-defense trade-offs in plant stress responses. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:2261-2274. [PMID: 30793201 DOI: 10.1093/jxb/erz066] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/07/2019] [Indexed: 05/11/2023]
Abstract
The evolutionarily conserved protein kinase complexes SnRK1 and TOR are central metabolic regulators essential for plant growth, development, and stress responses. They are activated by opposite signals, and the outcome of their activation is, in global terms, antagonistic. Similarly to their yeast and animal counterparts, SnRK1 is activated by the energy deficit often associated with stress to restore homeostasis, while TOR is activated in nutrient-rich conditions to promote growth. Recent evidence suggests that SnRK1 represses TOR in plants, revealing evolutionary conservation also in their crosstalk. Given their importance for integrating environmental information into growth and developmental programs, these signaling pathways hold great promise for reducing the growth penalties caused by stress. Here we review the literature connecting SnRK1 and TOR to plant stress responses. Although SnRK1 and TOR emerge mostly as positive regulators of defense and growth, respectively, the outcome of their activities in plant growth and performance is not always straightforward. Manipulation of both pathways under similar experimental setups, as well as further biochemical and genetic analyses of their molecular and functional interaction, is essential to fully understand the mechanisms through which these two metabolic pathways contribute to stress responses, growth, and development.
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Affiliation(s)
- Leonor Margalha
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande,Oeiras, Portugal
| | - Ana Confraria
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande,Oeiras, Portugal
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