1
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Guarini N, Saliba E, André B. Phosphoregulation of the yeast Pma1 H+-ATPase autoinhibitory domain involves the Ptk1/2 kinases and the Glc7 PP1 phosphatase and is under TORC1 control. PLoS Genet 2024; 20:e1011121. [PMID: 38227612 PMCID: PMC10817110 DOI: 10.1371/journal.pgen.1011121] [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: 07/10/2023] [Revised: 01/26/2024] [Accepted: 01/03/2024] [Indexed: 01/18/2024] Open
Abstract
Plasma membrane (PM) H+-ATPases of the P-type family are highly conserved in yeast, other fungi, and plants. Their main role is to establish an H+ gradient driving active transport of small ions and metabolites across the PM and providing the main component of the PM potential. Furthermore, in both yeast and plant cells, conditions have been described under which active H+-ATPases promote activation of TORC1, the rapamycin-sensitive kinase complex controlling cell growth. Fungal and plant PM H+-ATPases are self-inhibited by their respective cytosolic carboxyterminal tails unless this domain is phosphorylated at specific residues. In the yeast H+-ATPase Pma1, neutralization of this autoinhibitory domain depends mostly on phosphorylation of the adjacent Ser911 and Thr912 residues, but the kinase(s) and phosphatase(s) controlling this tandem phosphorylation remain unknown. In this study, we show that S911-T912 phosphorylation in Pma1 is mediated by the largely redundant Ptk1 and Ptk2 kinase paralogs. Dephosphorylation of S911-T912, as occurs under glucose starvation, is dependent on the Glc7 PP1 phosphatase. Furthermore, proper S911-T912 phosphorylation in Pma1 is required for optimal TORC1 activation upon H+ influx coupled amino-acid uptake. We finally show that TORC1 controls S911-T912 phosphorylation in a manner suggesting that activated TORC1 promotes feedback inhibition of Pma1. Our results shed important new light on phosphoregulation of the yeast Pma1 H+-ATPase and on its interconnections with TORC1.
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Affiliation(s)
- Nadia Guarini
- Molecular Physiology of the Cell, Université Libre de Bruxelles (ULB), Biopark, Gosselies, Belgium
| | - Elie Saliba
- Molecular Physiology of the Cell, Université Libre de Bruxelles (ULB), Biopark, Gosselies, Belgium
| | - Bruno André
- Molecular Physiology of the Cell, Université Libre de Bruxelles (ULB), Biopark, Gosselies, Belgium
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2
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Goul C, Peruzzo R, Zoncu R. The molecular basis of nutrient sensing and signalling by mTORC1 in metabolism regulation and disease. Nat Rev Mol Cell Biol 2023; 24:857-875. [PMID: 37612414 DOI: 10.1038/s41580-023-00641-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2023] [Indexed: 08/25/2023]
Abstract
The Ser/Thr kinase mechanistic target of rapamycin (mTOR) is a central regulator of cellular metabolism. As part of mTOR complex 1 (mTORC1), mTOR integrates signals such as the levels of nutrients, growth factors, energy sources and oxygen, and triggers responses that either boost anabolism or suppress catabolism. mTORC1 signalling has wide-ranging consequences for the growth and homeostasis of key tissues and organs, and its dysregulated activity promotes cancer, type 2 diabetes, neurodegeneration and other age-related disorders. How mTORC1 integrates numerous upstream cues and translates them into specific downstream responses is an outstanding question with major implications for our understanding of physiology and disease mechanisms. In this Review, we discuss recent structural and functional insights into the molecular architecture of mTORC1 and its lysosomal partners, which have greatly increased our mechanistic understanding of nutrient-dependent mTORC1 regulation. We also discuss the emerging involvement of aberrant nutrient-mTORC1 signalling in multiple diseases.
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Affiliation(s)
- Claire Goul
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberta Peruzzo
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
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3
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McGinnis MM, Sutter BM, Jahangiri S, Tu BP. Exonuclease Xrn1 regulates TORC1 signaling in response to SAM availability. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.28.559955. [PMID: 37808861 PMCID: PMC10557749 DOI: 10.1101/2023.09.28.559955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Autophagy is a conserved process of cellular self-digestion that promotes survival during nutrient stress. In yeast, methionine starvation is sufficient to induce autophagy. One pathway of autophagy induction is governed by the SEACIT complex, which regulates TORC1 activity in response to amino acids through the Rag GTPases Gtr1 and Gtr2. However, the precise mechanism by which SEACIT senses amino acids and regulates TORC1 signaling remains incompletely understood. Here, we identify the conserved 5'-3' RNA exonuclease Xrn1 as a surprising and novel regulator of TORC1 activity in response to methionine starvation. This role of Xrn1 is dependent on its catalytic activity, but not on degradation of any specific class of mRNAs. Instead, Xrn1 modulates the nucleotide-binding state of the Gtr1/2 complex, which is critical for its interaction with and activation of TORC1. This work identifies a critical role for Xrn1 in nutrient sensing and growth control that extends beyond its canonical housekeeping function in RNA degradation and indicates an avenue for RNA metabolism to function in amino acid signaling into TORC1.
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Affiliation(s)
- Madeline M McGinnis
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Benjamin M Sutter
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Samira Jahangiri
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Benjamin P Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
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4
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Jansen RM, Hurley JH. Longin domain GAP complexes in nutrient signalling, membrane traffic and neurodegeneration. FEBS Lett 2023; 597:750-761. [PMID: 36367440 PMCID: PMC10050129 DOI: 10.1002/1873-3468.14538] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 11/01/2022] [Accepted: 11/07/2022] [Indexed: 11/13/2022]
Abstract
Small GTPases act as molecular switches and control numerous cellular processes by their binding and hydrolysis of guanosine triphosphate (GTP). The activity of small GTPases is coordinated by guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). Recent structural and functional studies have characterized a subset of GAPs whose catalytic units consist of longin domains. Longin domain containing GAPs regulate small GTPases that facilitate nutrient signalling, autophagy, vesicular trafficking and lysosome homeostasis. All known examples in this GAP family function as part of larger multiprotein complexes. The three characterized mammalian protein complexes in this class are FLCN:FNIP, GATOR1 and C9orf72:SMCR8. Each complex carries out a unique cellular function by regulating distinct small GTPases. In this article, we explore the roles of longin domain GAPs in nutrient sensing, membrane dynamic, vesicular trafficking and disease. Through a structural lens, we examine the mechanism of each longin domain GAP and highlight potential therapeutic applications.
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Affiliation(s)
- Rachel M. Jansen
- Department of Molecular and Cell Biology, University of California Berkeley; Berkeley CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
| | - James H. Hurley
- Department of Molecular and Cell Biology, University of California Berkeley; Berkeley CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
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5
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Deprez MA, Caligaris M, Rosseels J, Hatakeyama R, Ghillebert R, Sampaio-Marques B, Mudholkar K, Eskes E, Meert E, Ungermann C, Ludovico P, Rospert S, De Virgilio C, Winderickx J. The nutrient-responsive CDK Pho85 primes the Sch9 kinase for its activation by TORC1. PLoS Genet 2023; 19:e1010641. [PMID: 36791155 PMCID: PMC9974134 DOI: 10.1371/journal.pgen.1010641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 02/28/2023] [Accepted: 01/27/2023] [Indexed: 02/16/2023] Open
Abstract
Yeast cells maintain an intricate network of nutrient signaling pathways enabling them to integrate information on the availability of different nutrients and adjust their metabolism and growth accordingly. Cells that are no longer capable of integrating this information, or that are unable to make the necessary adaptations, will cease growth and eventually die. Here, we studied the molecular basis underlying the synthetic lethality caused by loss of the protein kinase Sch9, a key player in amino acid signaling and proximal effector of the conserved growth-regulatory TORC1 complex, when combined with either loss of the cyclin-dependent kinase (CDK) Pho85 or loss of its inhibitor Pho81, which both have pivotal roles in phosphate sensing and cell cycle regulation. We demonstrate that it is specifically the CDK-cyclin pair Pho85-Pho80 or the partially redundant CDK-cyclin pairs Pho85-Pcl6/Pcl7 that become essential for growth when Sch9 is absent. Interestingly, the respective three CDK-cyclin pairs regulate the activity and distribution of the phosphatidylinositol-3 phosphate 5-kinase Fab1 on endosomes and vacuoles, where it generates phosphatidylinositol-3,5 bisphosphate that serves to recruit both TORC1 and its substrate Sch9. In addition, Pho85-Pho80 directly phosphorylates Sch9 at Ser726, and to a lesser extent at Thr723, thereby priming Sch9 for its subsequent phosphorylation and activation by TORC1. The TORC1-Sch9 signaling branch therefore integrates Pho85-mediated information at different levels. In this context, we also discovered that loss of the transcription factor Pho4 rescued the synthetic lethality caused by loss of Pho85 and Sch9, indicating that both signaling pathways also converge on Pho4, which appears to be wired to a feedback loop involving the high-affinity phosphate transporter Pho84 that fine-tunes Sch9-mediated responses.
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Affiliation(s)
- Marie-Anne Deprez
- Department of Biology, Functional Biology, KU Leuven, Heverlee, Belgium
| | - Marco Caligaris
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Joëlle Rosseels
- Department of Biology, Functional Biology, KU Leuven, Heverlee, Belgium
| | - Riko Hatakeyama
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, United Kingdom
| | - Ruben Ghillebert
- Department of Biology, Functional Biology, KU Leuven, Heverlee, Belgium
| | - Belém Sampaio-Marques
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s—PT Government Associate Laboratory, Braga/Guimarães, Braga, Portugal
| | - Kaivalya Mudholkar
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Elja Eskes
- Department of Biology, Functional Biology, KU Leuven, Heverlee, Belgium
| | - Els Meert
- Department of Biology, Functional Biology, KU Leuven, Heverlee, Belgium
| | - Christian Ungermann
- Department of Biology/Chemistry & Center of Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Paula Ludovico
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s—PT Government Associate Laboratory, Braga/Guimarães, Braga, Portugal
| | - Sabine Rospert
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Claudio De Virgilio
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- * E-mail: (CDV); (JW)
| | - Joris Winderickx
- Department of Biology, Functional Biology, KU Leuven, Heverlee, Belgium
- * E-mail: (CDV); (JW)
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6
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Botman D, Kanagasabapathi S, Savakis P, Teusink B. Using the AKAR3-EV biosensor to assess Sch9p- and PKA-signalling in budding yeast. FEMS Yeast Res 2023; 23:foad029. [PMID: 37173282 PMCID: PMC10237333 DOI: 10.1093/femsyr/foad029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 05/01/2023] [Accepted: 05/10/2023] [Indexed: 05/15/2023] Open
Abstract
Budding yeast uses the TORC1-Sch9p and cAMP-PKA signalling pathways to regulate adaptations to changing nutrient environments. Dynamic and single-cell measurements of the activity of these cascades will improve our understanding of the cellular adaptation of yeast. Here, we employed the AKAR3-EV biosensor developed for mammalian cells to measure the cellular phosphorylation status determined by Sch9p and PKA activity in budding yeast. Using various mutant strains and inhibitors, we show that AKAR3-EV measures the Sch9p- and PKA-dependent phosphorylation status in intact yeast cells. At the single-cell level, we found that the phosphorylation responses are homogenous for glucose, sucrose, and fructose, but heterogeneous for mannose. Cells that start to grow after a transition to mannose correspond to higher normalized Förster resonance energy transfer (FRET) levels, in line with the involvement of Sch9p and PKA pathways to stimulate growth-related processes. The Sch9p and PKA pathways have a relatively high affinity for glucose (K0.5 of 0.24 mM) under glucose-derepressed conditions. Lastly, steady-state FRET levels of AKAR3-EV seem to be independent of growth rates, suggesting that Sch9p- and PKA-dependent phosphorylation activities are transient responses to nutrient transitions. We believe that the AKAR3-EV sensor is an excellent addition to the biosensor arsenal for illuminating cellular adaptation in single yeast cells.
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Affiliation(s)
- Dennis Botman
- Systems Biology Lab, AIMMS/A-LIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Sineka Kanagasabapathi
- Systems Biology Lab, AIMMS/A-LIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Philipp Savakis
- Systems Biology Lab, AIMMS/A-LIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Bas Teusink
- Systems Biology Lab, AIMMS/A-LIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
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7
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Asrani K, Woo J, Mendes AA, Schaffer E, Vidotto T, Villanueva CR, Feng K, Oliveira L, Murali S, Liu HB, Salles DC, Lam B, Argani P, Lotan TL. An mTORC1-mediated negative feedback loop constrains amino acid-induced FLCN-Rag activation in renal cells with TSC2 loss. Nat Commun 2022; 13:6808. [PMID: 36357396 PMCID: PMC9649702 DOI: 10.1038/s41467-022-34617-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/01/2022] [Indexed: 11/12/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates inputs from growth factors and nutrients, but how mTORC1 autoregulates its activity remains unclear. The MiT/TFE transcription factors are phosphorylated and inactivated by mTORC1 following lysosomal recruitment by RagC/D GTPases in response to amino acid stimulation. We find that starvation-induced lysosomal localization of the RagC/D GAP complex, FLCN:FNIP2, is markedly impaired in a mTORC1-sensitive manner in renal cells with TSC2 loss, resulting in unexpected TFEB hypophosphorylation and activation upon feeding. TFEB phosphorylation in TSC2-null renal cells is partially restored by destabilization of the lysosomal folliculin complex (LFC) induced by FLCN mutants and is fully rescued by forced lysosomal localization of the FLCN:FNIP2 dimer. Our data indicate that a negative feedback loop constrains amino acid-induced, FLCN:FNIP2-mediated RagC activity in renal cells with constitutive mTORC1 signaling, and the resulting MiT/TFE hyperactivation may drive oncogenesis with loss of the TSC2 tumor suppressor.
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Affiliation(s)
- Kaushal Asrani
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Juhyung Woo
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Adrianna A. Mendes
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Ethan Schaffer
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Thiago Vidotto
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Clarence Rachel Villanueva
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Kewen Feng
- grid.21107.350000 0001 2171 9311Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Lia Oliveira
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Sanjana Murali
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Hans B. Liu
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Daniela C. Salles
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Brandon Lam
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Pedram Argani
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Tamara L. Lotan
- grid.21107.350000 0001 2171 9311Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA ,grid.21107.350000 0001 2171 9311Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD USA ,grid.21107.350000 0001 2171 9311Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD USA
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8
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Phosphoproteomic responses of TORC1 target kinases reveal discrete and convergent mechanisms that orchestrate the quiescence program in yeast. Cell Rep 2021; 37:110149. [PMID: 34965436 DOI: 10.1016/j.celrep.2021.110149] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 10/19/2021] [Accepted: 11/30/2021] [Indexed: 01/18/2023] Open
Abstract
The eukaryotic TORC1 kinase assimilates diverse environmental cues, including growth factors and nutrients, to control growth by tuning anabolic and catabolic processes. In yeast, TORC1 stimulates protein synthesis in response to abundant nutrients primarily through its proximal effector kinase Sch9. Conversely, TORC1 inhibition following nutrient limitation unlocks various distally controlled kinases (e.g., Atg1, Gcn2, Npr1, Rim15, Slt2/Mpk1, and Yak1), which cooperate through poorly defined circuits to orchestrate the quiescence program. To better define the signaling landscape of the latter kinases, we use in vivo quantitative phosphoproteomics. Through pinpointing known and uncharted Npr1, Rim15, Slt2/Mpk1, and Yak1 effectors, our study examines the architecture of the distally controlled TORC1 kinase network. Accordingly, this is built on a combination of discrete, convergent, and multilayered feedback regulatory mechanisms, which likely ensure homeostatic control of and/or robust responses by TORC1 and its effector kinases under fluctuating nutritional conditions.
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9
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Calvo IA, Sharma S, Paulo JA, Gulka AO, Boeszoermenyi A, Zhang J, Lombana JM, Palmieri CM, Laviolette LA, Arthanari H, Iliopoulos O, Gygi SP, Motamedi M. The fission yeast FLCN/FNIP complex augments TORC1 repression or activation in response to amino acid (AA) availability. iScience 2021; 24:103338. [PMID: 34805795 PMCID: PMC8590082 DOI: 10.1016/j.isci.2021.103338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/10/2021] [Accepted: 10/21/2021] [Indexed: 11/13/2022] Open
Abstract
The target of Rapamycin complex1 (TORC1) senses and integrates several environmental signals, including amino acid (AA) availability, to regulate cell growth. Folliculin (FLCN) is a tumor suppressor (TS) protein in renal cell carcinoma, which paradoxically activates TORC1 in response to AA supplementation. Few tractable systems for modeling FLCN as a TS are available. Here, we characterize the FLCN-containing complex in Schizosaccharomyces pombe (called BFC) and show that BFC augments TORC1 repression and activation in response to AA starvation and supplementation, respectively. BFC co-immunoprecipitates V-ATPase, a TORC1 modulator, and regulates its activity in an AA-dependent manner. BFC genetic and proteomic networks identify the conserved peptide transmembrane transporter Ptr2 and the phosphoribosylformylglycinamidine synthase Ade3 as new AA-dependent regulators of TORC1. Overall, these data ascribe an additional repressive function to Folliculin in TORC1 regulation and reveal S. pombe as an excellent system for modeling the AA-dependent, FLCN-mediated repression of TORC1 in eukaryotes.
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Affiliation(s)
- Isabel A. Calvo
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Shalini Sharma
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Joao A. Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Alexander O.D. Gulka
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Andras Boeszoermenyi
- Department of Biochemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Jingyu Zhang
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Jose M. Lombana
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Christina M. Palmieri
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Laura A. Laviolette
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
| | - Haribabu Arthanari
- Department of Biochemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Othon Iliopoulos
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
- Division of Hematology-Oncology, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Steven P. Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Mo Motamedi
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine Harvard Medical School, Charlestown, MA 02129, USA
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10
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Indole-3-acetic acid is a physiological inhibitor of TORC1 in yeast. PLoS Genet 2021; 17:e1009414. [PMID: 33690632 PMCID: PMC7978357 DOI: 10.1371/journal.pgen.1009414] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 03/19/2021] [Accepted: 02/11/2021] [Indexed: 01/13/2023] Open
Abstract
Indole-3-acetic acid (IAA) is the most common, naturally occurring phytohormone that regulates cell division, differentiation, and senescence in plants. The capacity to synthesize IAA is also widespread among plant-associated bacterial and fungal species, which may use IAA as an effector molecule to define their relationships with plants or to coordinate their physiological behavior through cell-cell communication. Fungi, including many species that do not entertain a plant-associated life style, are also able to synthesize IAA, but the physiological role of IAA in these fungi has largely remained enigmatic. Interestingly, in this context, growth of the budding yeast Saccharomyces cerevisiae is sensitive to extracellular IAA. Here, we use a combination of various genetic approaches including chemical-genetic profiling, SAturated Transposon Analysis in Yeast (SATAY), and genetic epistasis analyses to identify the mode-of-action by which IAA inhibits growth in yeast. Surprisingly, these analyses pinpointed the target of rapamycin complex 1 (TORC1), a central regulator of eukaryotic cell growth, as the major growth-limiting target of IAA. Our biochemical analyses further demonstrate that IAA inhibits TORC1 both in vivo and in vitro. Intriguingly, we also show that yeast cells are able to synthesize IAA and specifically accumulate IAA upon entry into stationary phase. Our data therefore suggest that IAA contributes to proper entry of yeast cells into a quiescent state by acting as a metabolic inhibitor of TORC1. Auxins are a major group of plant phytohormones that are critical for growth and development. Amongst the auxins, indole-3-acetic acid (IAA) is the most common, naturally occurring phytohormone that regulates cell division, differentiation, and senescence in plants. Interestingly, the capacity to synthesize and secrete IAA is also widespread among fungi, including the budding yeast Saccharomyces cerevisiae, but the role of IAA in fungi has largely remained unknown. Here, we confirm an earlier observation that IAA inhibits growth of budding yeast and show by diverse genetic and biochemical means that IAA restrains budding yeast growth by inhibiting the target of rapamycin complex 1 (TORC1), a highly conserved eukaryotic regulator of growth. Intriguingly, budding yeast cells accumulate IAA specifically when limited for nutrients, which suggests that IAA plays a hitherto unknown physiological role in contributing to the establishment of cellular quiescence by acting as a metabolic inhibitor of TORC1.
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11
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Chen Z, Malia PC, Hatakeyama R, Nicastro R, Hu Z, Péli-Gulli MP, Gao J, Nishimura T, Eskes E, Stefan CJ, Winderickx J, Dengjel J, De Virgilio C, Ungermann C. TORC1 Determines Fab1 Lipid Kinase Function at Signaling Endosomes and Vacuoles. Curr Biol 2020; 31:297-309.e8. [PMID: 33157024 DOI: 10.1016/j.cub.2020.10.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/25/2020] [Accepted: 10/08/2020] [Indexed: 01/17/2023]
Abstract
Organelles of the endomembrane system maintain their identity and integrity during growth or stress conditions by homeostatic mechanisms that regulate membrane flux and biogenesis. At lysosomes and endosomes, the Fab1 lipid kinase complex and the nutrient-regulated target of rapamycin complex 1 (TORC1) control the integrity of the endolysosomal homeostasis and cellular metabolism. Both complexes are functionally connected as Fab1-dependent generation of PI(3,5)P2 supports TORC1 activity. Here, we identify Fab1 as a target of TORC1 on signaling endosomes, which are distinct from multivesicular bodies, and provide mechanistic insight into their crosstalk. Accordingly, TORC1 can phosphorylate Fab1 proximal to its PI3P-interacting FYVE domain, which causes Fab1 to shift to signaling endosomes, where it generates PI(3,5)P2. This, in turn, regulates (1) vacuole morphology, (2) recruitment of TORC1 and the TORC1-regulatory Rag GTPase-containing EGO complex to signaling endosomes, and (3) TORC1 activity. Thus, our study unravels a regulatory feedback loop between TORC1 and the Fab1 complex that controls signaling at endolysosomes.
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Affiliation(s)
- Zilei Chen
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany
| | - Pedro Carpio Malia
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany
| | - Riko Hatakeyama
- Department of Biology, University of Fribourg, Chemin du Musée, CH-1700 Fribourg, Switzerland
| | - Raffaele Nicastro
- Department of Biology, University of Fribourg, Chemin du Musée, CH-1700 Fribourg, Switzerland
| | - Zehan Hu
- Department of Biology, University of Fribourg, Chemin du Musée, CH-1700 Fribourg, Switzerland
| | - Marie-Pierre Péli-Gulli
- Department of Biology, University of Fribourg, Chemin du Musée, CH-1700 Fribourg, Switzerland
| | - Jieqiong Gao
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany
| | - Taki Nishimura
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Elja Eskes
- Functional Biology, KU Leuven, Kasteelpark Arensberg 31, 3000 Leuven, Belgium
| | - Christopher J Stefan
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Joris Winderickx
- Functional Biology, KU Leuven, Kasteelpark Arensberg 31, 3000 Leuven, Belgium
| | - Jörn Dengjel
- Department of Biology, University of Fribourg, Chemin du Musée, CH-1700 Fribourg, Switzerland
| | - Claudio De Virgilio
- Department of Biology, University of Fribourg, Chemin du Musée, CH-1700 Fribourg, Switzerland.
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany; Center of Cellular Nanoanalytics Osnabrück (CellNanOs), University of Osnabrück, Barbarastrasse 11, 49076 Osnabrück, Germany.
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12
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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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13
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El-Houjeiri L, Possik E, Vijayaraghavan T, Paquette M, Martina JA, Kazan JM, Ma EH, Jones R, Blanchette P, Puertollano R, Pause A. The Transcription Factors TFEB and TFE3 Link the FLCN-AMPK Signaling Axis to Innate Immune Response and Pathogen Resistance. Cell Rep 2020; 26:3613-3628.e6. [PMID: 30917316 DOI: 10.1016/j.celrep.2019.02.102] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 10/22/2018] [Accepted: 02/25/2019] [Indexed: 12/11/2022] Open
Abstract
TFEB and TFE3 are transcriptional regulators of the innate immune response, but the mechanisms regulating their activation upon pathogen infection are poorly elucidated. Using C. elegans and mammalian models, we report that the master metabolic modulator 5'-AMP-activated protein kinase (AMPK) and its negative regulator Folliculin (FLCN) act upstream of TFEB/TFE3 in the innate immune response, independently of the mTORC1 signaling pathway. In nematodes, loss of FLCN or overexpression of AMPK confers pathogen resistance via activation of TFEB/TFE3-dependent antimicrobial genes, whereas ablation of total AMPK activity abolishes this phenotype. Similarly, in mammalian cells, loss of FLCN or pharmacological activation of AMPK induces TFEB/TFE3-dependent pro-inflammatory cytokine expression. Importantly, a rapid reduction in cellular ATP levels in murine macrophages is observed upon lipopolysaccharide (LPS) treatment accompanied by an acute AMPK activation and TFEB nuclear localization. These results uncover an ancient, highly conserved, and pharmacologically actionable mechanism coupling energy status with innate immunity.
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Affiliation(s)
- Leeanna El-Houjeiri
- Goodman Cancer Research Center, McGill University, Montréal, QC, Canada; Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Elite Possik
- Goodman Cancer Research Center, McGill University, Montréal, QC, Canada; Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Tarika Vijayaraghavan
- Goodman Cancer Research Center, McGill University, Montréal, QC, Canada; Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Mathieu Paquette
- Goodman Cancer Research Center, McGill University, Montréal, QC, Canada; Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - José A Martina
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
| | - Jalal M Kazan
- Goodman Cancer Research Center, McGill University, Montréal, QC, Canada; Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Eric H Ma
- Goodman Cancer Research Center, McGill University, Montréal, QC, Canada; Department of Physiology, McGill University, Montréal, QC, Canada
| | - Russell Jones
- Goodman Cancer Research Center, McGill University, Montréal, QC, Canada; Department of Physiology, McGill University, Montréal, QC, Canada
| | - Paola Blanchette
- Goodman Cancer Research Center, McGill University, Montréal, QC, Canada; Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Rosa Puertollano
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
| | - Arnim Pause
- Goodman Cancer Research Center, McGill University, Montréal, QC, Canada; Department of Biochemistry, McGill University, Montréal, QC, Canada.
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14
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de Martín Garrido N, Aylett CHS. Nutrient Signaling and Lysosome Positioning Crosstalk Through a Multifunctional Protein, Folliculin. Front Cell Dev Biol 2020; 8:108. [PMID: 32195250 PMCID: PMC7063858 DOI: 10.3389/fcell.2020.00108] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 02/10/2020] [Indexed: 12/16/2022] Open
Abstract
FLCN was identified as the gene responsible for Birt-Hogg-Dubé (BHD) syndrome, a hereditary syndrome associated with the appearance of familiar renal oncocytomas. Most mutations affecting FLCN result in the truncation of the protein, and therefore loss of its associated functions, as typical for a tumor suppressor. FLCN encodes the protein folliculin (FLCN), which is involved in numerous biological processes; mutations affecting this protein thus lead to different phenotypes depending on the cellular context. FLCN forms complexes with two large interacting proteins, FNIP1 and FNIP2. Structural studies have shown that both FLCN and FNIPs contain longin and differentially expressed in normal versus neoplastic cells (DENN) domains, typically involved in the regulation of small GTPases. Accordingly, functional studies show that FLCN regulates both the Rag and the Rab GTPases depending on nutrient availability, which are respectively involved in the mTORC1 pathway and lysosomal positioning. Although recent structural studies shed light on the precise mechanism by which FLCN regulates the Rag GTPases, which in turn regulate mTORC1, how FLCN regulates membrane trafficking through the Rab GTPases or the significance of the intriguing FLCN-FNIP-AMPK complex formation are questions that still remain unanswered. We discuss the recent progress in our understanding of FLCN regulation of both growth signaling and lysosomal positioning, as well as future approaches to establish detailed mechanisms to explain the disparate phenotypes caused by the loss of FLCN function and the development of BHD-associated and other tumors.
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Affiliation(s)
| | - Christopher H. S. Aylett
- Section for Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
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15
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N-Terminal Acetylation by NatB Is Required for the Shutoff Activity of Influenza A Virus PA-X. Cell Rep 2020; 24:851-860. [PMID: 30044982 DOI: 10.1016/j.celrep.2018.06.078] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 03/26/2018] [Accepted: 06/18/2018] [Indexed: 12/17/2022] Open
Abstract
N-terminal acetylation is a major posttranslational modification in eukaryotes catalyzed by N-terminal acetyltransferases (NATs), NatA through NatF. Although N-terminal acetylation modulates diverse protein functions, little is known about its roles in virus replication. We found that NatB, which comprises NAA20 and NAA25, is involved in the shutoff activity of influenza virus PA-X. The shutoff activity of PA-X was suppressed in NatB-deficient cells, and PA-X mutants that are not acetylated by NatB showed reduced shutoff activities. We also evaluated the importance of N-terminal acetylation of PA, because PA-X shares its N-terminal sequence with PA. Viral polymerase activity was reduced in NatB-deficient cells. Moreover, mutant PAs that are not acetylated by NatB lost their function in the viral polymerase complex. Taken together, our findings demonstrate that N-terminal acetylation is required for the shutoff activity of PA-X and for viral polymerase activity.
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16
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Deprez MA, Eskes E, Winderickx J, Wilms T. The TORC1-Sch9 pathway as a crucial mediator of chronological lifespan in the yeast Saccharomyces cerevisiae. FEMS Yeast Res 2019; 18:4980911. [PMID: 29788208 DOI: 10.1093/femsyr/foy048] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 04/19/2018] [Indexed: 12/18/2022] Open
Abstract
The concept of ageing is one that has intrigued mankind since the beginning of time and is now more important than ever as the incidence of age-related disorders is increasing in our ageing population. Over the past decades, extensive research has been performed using various model organisms. As such, it has become apparent that many fundamental aspects of biological ageing are highly conserved across large evolutionary distances. In this review, we illustrate that the unicellular eukaryotic organism Saccharomyces cerevisiae has proven to be a valuable tool to gain fundamental insights into the molecular mechanisms of cellular ageing in multicellular eukaryotes. In addition, we outline the current knowledge on how downregulation of nutrient signaling through the target of rapamycin (TOR)-Sch9 pathway or reducing calorie intake attenuates many detrimental effects associated with ageing and leads to the extension of yeast chronological lifespan. Given that both TOR Complex 1 (TORC1) and Sch9 have mammalian orthologues that have been implicated in various age-related disorders, unraveling the connections of TORC1 and Sch9 with yeast ageing may provide additional clues on how their mammalian orthologues contribute to the mechanisms underpinning human ageing and health.
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Affiliation(s)
- Marie-Anne Deprez
- Department of Biology, Functional Biology, KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Elja Eskes
- Department of Biology, Functional Biology, KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Joris Winderickx
- Department of Biology, Functional Biology, KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Tobias Wilms
- Department of Biology, Functional Biology, KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
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17
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The lysosome as a cellular centre for signalling, metabolism and quality control. Nat Cell Biol 2019; 21:133-142. [DOI: 10.1038/s41556-018-0244-7] [Citation(s) in RCA: 409] [Impact Index Per Article: 81.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/31/2018] [Indexed: 02/06/2023]
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18
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Varlakhanova NV, Tornabene BA, Ford MGJ. Ivy1 is a negative regulator of Gtr-dependent TORC1 activation. J Cell Sci 2018; 131:jcs.218305. [PMID: 30097557 DOI: 10.1242/jcs.218305] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 07/27/2018] [Indexed: 11/20/2022] Open
Abstract
The highly conserved TORC1 complex controls cell growth in response to nutrients, especially amino acids. The EGO complex activates TORC1 in response to glutamine and leucine. Here, we demonstrate that the I-BAR domain-containing protein Ivy1 colocalizes with Gtr1 and Gtr2, a heterodimer of small GTPases that are part of the EGO complex. Ivy1 is a negative regulator of Gtr-induced TORC1 activation, and is contained within puncta associated with the vacuolar membrane in cells grown in nutrient-rich medium or after brief nitrogen starvation. Addition of glutamine to nitrogen-starved cells leads to dissipation of Ivy1 puncta and redistribution of Ivy1 throughout the vacuolar membrane. Continued stimulation with glutamine results in concentration of Ivy1 within vacuolar membrane invaginations and its spatial separation from the EGO complex components Gtr1 and Gtr2. Disruption of vacuolar membrane invagination is associated with persistent mislocalization of Ivy1 across the vacuolar membrane and inhibition of TORC1 activity. Together, our findings illustrate a novel negative-feedback pathway that is exerted by Ivy1 on Gtr-dependent TORC1 signaling and provide insight into a potential molecular mechanism underlying TORC1 activation by vacuolar membrane remodeling.
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Affiliation(s)
- Natalia V Varlakhanova
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, United States of America
| | - Bryan A Tornabene
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, United States of America
| | - Marijn G J Ford
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, United States of America
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19
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Abstract
Background The protein kinase Target Of Rapamycin (TOR) is a nexus for the regulation of eukaryotic cell growth. TOR assembles into one of two distinct signalling complexes, TOR complex 1 (TORC1) and TORC2 (mTORC1/2 in mammals), with a set of largely non-overlapping protein partners. (m)TORC1 activation occurs in response to a series of stimuli relevant to cell growth, including nutrient availability, growth factor signals and stress, and regulates much of the cell's biosynthetic activity, from proteins to lipids, and recycling through autophagy. mTORC1 regulation is of great therapeutic significance, since in humans many of these signalling complexes, alongside subunits of mTORC1 itself, are implicated in a wide variety of pathophysiologies, including multiple types of cancer, neurological disorders, neurodegenerative diseases and metabolic disorders including diabetes. Methodology Recent years have seen numerous structures determined of (m)TOR, which have provided mechanistic insight into (m)TORC1 activation in particular, however the integration of cellular signals occurs upstream of the kinase and remains incompletely understood. Here we have collected and analysed in detail as many as possible of the molecular and structural studies which have shed light on (m)TORC1 repression, activation and signal integration. Conclusions A molecular understanding of this signal integration pathway is required to understand how (m)TORC1 activation is reconciled with the many diverse and contradictory stimuli affecting cell growth. We discuss the current level of molecular understanding of the upstream components of the (m)TORC1 signalling pathway, recent progress on this key biochemical frontier, and the future studies necessary to establish a mechanistic understanding of this master-switch for eukaryotic cell growth.
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Affiliation(s)
- Kailash Ramlaul
- Section of Structural Biology, Department of Medicine, Imperial College London, SW7 2AZ, UK
| | - Christopher H S Aylett
- Section of Structural Biology, Department of Medicine, Imperial College London, SW7 2AZ, UK
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20
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Meng J, Ferguson SM. GATOR1-dependent recruitment of FLCN-FNIP to lysosomes coordinates Rag GTPase heterodimer nucleotide status in response to amino acids. J Cell Biol 2018; 217:2765-2776. [PMID: 29848618 PMCID: PMC6080935 DOI: 10.1083/jcb.201712177] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 04/29/2018] [Accepted: 05/08/2018] [Indexed: 01/08/2023] Open
Abstract
A large number of lysosome-localized proteins control mTORC1 signaling. Rag guanosine triphosphatase (GTPase) heterodimers play a central role in this pathway by recruiting mTORC1 to lysosomes. Meng and Ferguson reveal how folliculin, a tumor suppressor, coordinates nucleotide states within Rag GTPase heterodimers. Folliculin (FLCN) is a tumor suppressor that coordinates cellular responses to changes in amino acid availability via regulation of the Rag guanosine triphosphatases. FLCN is recruited to lysosomes during amino acid starvation, where it interacts with RagA/B as a heterodimeric complex with FLCN-interacting proteins (FNIPs). The FLCN–FNIP heterodimer also has GTPase-activating protein (GAP) activity toward RagC/D. These properties raised two important questions. First, how is amino acid availability sensed to regulate lysosomal abundance of FLCN? Second, what is the relationship between FLCN lysosome localization, RagA/B interactions, and RagC/D GAP activity? In this study, we show that RagA/B nucleotide status determines the FLCN–FNIP1 recruitment to lysosomes. Starvation-induced FLCN–FNIP lysosome localization requires GAP activity toward Rags 1 (GATOR1), the GAP that converts RagA/B to the guanosine diphosphate (GDP)-bound state. This places FLCN–FNIP recruitment to lysosomes under the control of amino acid sensors that act upstream of GATOR1. By binding to RagA/BGDP and acting on RagC/D, FLCN–FNIP can coordinate nucleotide status between Rag heterodimer subunits in response to changes in amino acid availability.
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Affiliation(s)
- Jin Meng
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT .,Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT
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