1
|
Füllbrunn N, Nicastro R, Mari M, Griffith J, Herrmann E, Rasche R, Borchers AC, Auffarth K, Kümmel D, Reggiori F, De Virgilio C, Langemeyer L, Ungermann C. The GTPase activating protein Gyp7 regulates Rab7/Ypt7 activity on late endosomes. J Cell Biol 2024; 223:e202305038. [PMID: 38536036 PMCID: PMC10978497 DOI: 10.1083/jcb.202305038] [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: 05/12/2023] [Revised: 01/22/2024] [Accepted: 03/08/2024] [Indexed: 04/01/2024] Open
Abstract
Organelles of the endomembrane system contain Rab GTPases as identity markers. Their localization is determined by guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). It remains largely unclear how these regulators are specifically targeted to organelles and how their activity is regulated. Here, we focus on the GAP Gyp7, which acts on the Rab7-like Ypt7 protein in yeast, and surprisingly observe the protein exclusively in puncta proximal to the vacuole. Mistargeting of Gyp7 to the vacuole strongly affects vacuole morphology, suggesting that endosomal localization is needed for function. In agreement, efficient endolysosomal transport requires Gyp7. In vitro assays reveal that Gyp7 requires a distinct lipid environment for membrane binding and activity. Overexpression of Gyp7 concentrates Ypt7 in late endosomes and results in resistance to rapamycin, an inhibitor of the target of rapamycin complex 1 (TORC1), suggesting that these late endosomes are signaling endosomes. We postulate that Gyp7 is part of regulatory machinery involved in late endosome function.
Collapse
Affiliation(s)
- Nadia Füllbrunn
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
- Center of Cellular Nanoanalytics, Osnabrück University, Osnabrück, Germany
| | - Raffaele Nicastro
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Muriel Mari
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Janice Griffith
- Department of Cell Biology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Eric Herrmann
- Institute of Biochemistry, University of Münster, Münster, Germany
| | - René Rasche
- Institute of Biochemistry, University of Münster, Münster, Germany
| | - Ann-Christin Borchers
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Kathrin Auffarth
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Daniel Kümmel
- Institute of Biochemistry, University of Münster, Münster, Germany
| | - Fulvio Reggiori
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Department of Cell Biology, University Medical Center Utrecht, Utrecht, Netherlands
| | | | - Lars Langemeyer
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
- Center of Cellular Nanoanalytics, Osnabrück University, Osnabrück, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
- Center of Cellular Nanoanalytics, Osnabrück University, Osnabrück, Germany
| |
Collapse
|
2
|
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.
Collapse
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)
| |
Collapse
|
3
|
Gokbayrak ZD, Patel D, Brett CL. Acetate and hypertonic stress stimulate vacuole membrane fission using distinct mechanisms. PLoS One 2022; 17:e0271199. [PMID: 35834522 PMCID: PMC9282455 DOI: 10.1371/journal.pone.0271199] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 06/25/2022] [Indexed: 11/19/2022] Open
Abstract
Vacuoles in plants and fungi play critical roles in cell metabolism and osmoregulation. To support these functions, vacuoles change their morphology, e.g. they fragment when these organisms are challenged with draught, high salinity or metabolic stress (e.g. acetate accumulation). In turn, morphology reflects an equilibrium between membrane fusion and fission that determines size, shape and copy number. By studying Saccharomyces cerevisiae and its vacuole as models, conserved molecular mechanisms responsible for fusion have been revealed. However, a detailed understanding of vacuole fission and how these opposing processes respond to metabolism or osmoregulation remain elusive. Herein we describe a new fluorometric assay to measure yeast vacuole fission in vitro. For proof–of–concept, we use this assay to confirm that acetate, a metabolic stressor, triggers vacuole fission and show it blocks homotypic vacuole fusion in vitro. Similarly, hypertonic stress induced by sorbitol or glucose caused robust vacuole fission in vitro whilst inhibiting fusion. Using wortmannin to inhibit phosphatidylinositol (PI) -kinases or rGyp1-46 to inactivate Rab–GTPases, we show that acetate stress likely targets PI signaling, whereas osmotic stress affects Rab signaling on vacuole membranes to stimulate fission. This study sets the stage for further investigation into the mechanisms that change vacuole morphology to support cell metabolism and osmoregulation.
Collapse
Affiliation(s)
| | - Dipti Patel
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | | |
Collapse
|
4
|
Gao J, Nicastro R, Péli-Gulli MP, Grziwa S, Chen Z, Kurre R, Piehler J, De Virgilio C, Fröhlich F, Ungermann C. The HOPS tethering complex is required to maintain signaling endosome identity and TORC1 activity. J Biophys Biochem Cytol 2022; 221:213121. [PMID: 35404387 PMCID: PMC9011323 DOI: 10.1083/jcb.202109084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 01/27/2022] [Accepted: 02/28/2022] [Indexed: 12/04/2022] Open
Abstract
The endomembrane system of eukaryotic cells is essential for cellular homeostasis during growth and proliferation. Previous work showed that a central regulator of growth, namely the target of rapamycin complex 1 (TORC1), binds both membranes of vacuoles and signaling endosomes (SEs) that are distinct from multivesicular bodies (MVBs). Interestingly, the endosomal TORC1, which binds membranes in part via the EGO complex, critically defines vacuole integrity. Here, we demonstrate that SEs form at a branch point of the biosynthetic and endocytic pathways toward the vacuole and depend on MVB biogenesis. Importantly, function of the HOPS tethering complex is essential to maintain the identity of SEs and proper endosomal and vacuolar TORC1 activities. In HOPS mutants, the EGO complex redistributed to the Golgi, which resulted in a partial mislocalization of TORC1. Our study uncovers that SE function requires a functional HOPS complex and MVBs, suggesting a tight link between trafficking and signaling along the endolysosomal pathway.
Collapse
Affiliation(s)
- Jieqiong Gao
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Raffaele Nicastro
- Department of Biology, University of Fribourg, Chemin du Musée, Fribourg, Switzerland
| | | | - Sophie Grziwa
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Zilei Chen
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Rainer Kurre
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
| | - Jacob Piehler
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
- Department of Biology/Chemistry, Biophysics Section, Osnabrück University, Osnabrück, Germany
| | - Claudio De Virgilio
- Department of Biology, University of Fribourg, Chemin du Musée, Fribourg, Switzerland
| | - Florian Fröhlich
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
- Department of Biology/Chemistry, Molecular Membrane Biology Section, Osnabrück University, Osnabrück, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
| |
Collapse
|
5
|
Reinheckel T, Tholen M. Low level lysosomal membrane permeabilization for limited release and sub-lethal functions of cathepsin proteases in the cytosol and nucleus. FEBS Open Bio 2022; 12:694-707. [PMID: 35203107 PMCID: PMC8972055 DOI: 10.1002/2211-5463.13385] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/21/2022] [Accepted: 02/15/2022] [Indexed: 11/12/2022] Open
Abstract
For a long time, lysosomes were purely seen as organelles in charge of garbage disposal within the cell. They destroy any cargo delivered into their lumen with a plethora of highly potent hydrolytic enzymes, including various proteases. In case of damage to their limiting membranes, the lysosomes release their soluble content with detrimental outcomes for the cell. In recent years however, this view of the lysosome changed towards acknowledging it as a platform for integration of manifold intra- and extracellular signals. Even impaired lysosomal membrane integrity is no longer considered to be a one-way street to cell death. Increasing evidence suggests that lysosomal enzymes, mainly cathepsin proteases, can be released in a spatially and temporarily restricted manner that is compatible with cellular survival. This way, cathepsins can act in the cytosol and the nucleus, where they affect important cellular processes such as cell division. Here, we review this evidence and discuss the routes and molecular mechanisms by which the cathepsins may reach their unusual destination.
Collapse
Affiliation(s)
- Thomas Reinheckel
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert Ludwigs University, Freiburg, Germany.,German Cancer Consortium (DKTK) Partner Site Freiburg, Freiburg, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,Center for Biological Signaling Studies BIOSS, Albert Ludwigs University, Freiburg, Germany
| | - Martina Tholen
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert Ludwigs University, Freiburg, Germany
| |
Collapse
|
6
|
Jin H, Tang Y, Yang L, Peng X, Li B, Fan Q, Wei S, Yang S, Li X, Wu B, Huang M, Tang S, Liu J, Li H. Rab GTPases: Central Coordinators of Membrane Trafficking in Cancer. Front Cell Dev Biol 2021; 9:648384. [PMID: 34141705 PMCID: PMC8204108 DOI: 10.3389/fcell.2021.648384] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 05/10/2021] [Indexed: 12/11/2022] Open
Abstract
Tumor progression involves invasion, migration, metabolism, autophagy, exosome secretion, and drug resistance. Cargos transported by membrane vesicle trafficking underlie all of these processes. Rab GTPases, which, through coordinated and dynamic intracellular membrane trafficking alongside cytoskeletal pathways, determine the maintenance of homeostasis and a series of cellular functions. The mechanism of vesicle movement regulated by Rab GTPases plays essential roles in cancers. Therefore, targeting Rab GTPases to adjust membrane trafficking has the potential to become a novel way to adjust cancer treatment. In this review, we describe the characteristics of Rab GTPases; in particular, we discuss the role of their activation in the regulation of membrane transport and provide examples of Rab GTPases regulating membrane transport in tumor progression. Finally, we discuss the clinical implications and the potential as a cancer therapeutic target of Rab GTPases.
Collapse
Affiliation(s)
- Hongyuan Jin
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Yuanxin Tang
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Liang Yang
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Xueqiang Peng
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Bowen Li
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Qin Fan
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Shibo Wei
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Shuo Yang
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Xinyu Li
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Bo Wu
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Mingyao Huang
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Shilei Tang
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Jingang Liu
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Hangyu Li
- Department of General Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| |
Collapse
|
7
|
Nagamatsu ST, Coutouné N, José J, Fiamenghi MB, Pereira GAG, Oliveira JVDC, Carazzolle MF. Ethanol production process driving changes on industrial strains. FEMS Yeast Res 2021; 21:6070656. [PMID: 33417685 DOI: 10.1093/femsyr/foaa071] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/04/2021] [Indexed: 12/16/2022] Open
Abstract
Ethanol production has key differences between the two largest producing countries of this biofuel, Brazil and the USA, such as feedstock source, sugar concentration and ethanol titers in industrial fermentation. Therefore, it is highly probable that these specificities have led to genome adaptation of the Saccharomyces cerevisiae strains employed in each process to tolerate different environments. In order to identify particular adaptations, in this work, we have compared the genomes of industrial yeast strains widely used to produce ethanol from sugarcane, corn and sweet sorghum, and also two laboratory strains as reference. The genes were predicted and then 4524 single-copy orthologous were selected to build the phylogenetic tree. We found that the geographic location and industrial process were shown as the main evolutionary drivers: for sugarcane fermentation, positive selection was identified for metal homeostasis and stress response genes, whereas genes involved in membrane modeling have been connected with corn fermentation. In addition, the corn specialized strain Ethanol Red showed an increased number of copies of MAL31, a gene encoding a maltose transporter. In summary, our work can help to guide new strain chassis selection for engineering strategies, to produce more robust strains for biofuel production and other industrial applications.
Collapse
Affiliation(s)
- Sheila Tiemi Nagamatsu
- Division of Human Genetics, Department of Psychiatry, Yale School of Medicine, 333 Cedar St, New Haven, CT, 06510, USA.,Laboratório de Genômica e BioEnergia, Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Campinas, São Paulo, 13083-970, Brazil
| | - Natalia Coutouné
- Laboratório Nacional de Biorrenováveis (LNBR), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), CEP 13083-970, Campinas, São Paulo, Brazil
| | - Juliana José
- Laboratório de Genômica e BioEnergia, Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Campinas, São Paulo, 13083-970, Brazil
| | - Mateus Bernabe Fiamenghi
- Laboratório de Genômica e BioEnergia, Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Campinas, São Paulo, 13083-970, Brazil
| | - Gonçalo Amarante Guimarães Pereira
- Laboratório de Genômica e BioEnergia, Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Campinas, São Paulo, 13083-970, Brazil
| | - Juliana Velasco de Castro Oliveira
- Laboratório Nacional de Biorrenováveis (LNBR), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), CEP 13083-970, Campinas, São Paulo, Brazil
| | - Marcelo Falsarella Carazzolle
- Laboratório de Genômica e BioEnergia, Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Campinas, São Paulo, 13083-970, Brazil
| |
Collapse
|
8
|
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.
Collapse
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.
| |
Collapse
|
9
|
Lees JA, Li P, Kumar N, Weisman LS, Reinisch KM. Insights into Lysosomal PI(3,5)P 2 Homeostasis from a Structural-Biochemical Analysis of the PIKfyve Lipid Kinase Complex. Mol Cell 2020; 80:736-743.e4. [PMID: 33098764 DOI: 10.1016/j.molcel.2020.10.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/11/2020] [Accepted: 10/01/2020] [Indexed: 11/30/2022]
Abstract
The phosphoinositide PI(3,5)P2, generated exclusively by the PIKfyve lipid kinase complex, is key for lysosomal biology. Here, we explore how PI(3,5)P2 levels within cells are regulated. We find the PIKfyve complex comprises five copies of the scaffolding protein Vac14 and one copy each of the lipid kinase PIKfyve, generating PI(3,5)P2 from PI3P and the lipid phosphatase Fig4, reversing the reaction. Fig4 is active as a lipid phosphatase in the ternary complex, whereas PIKfyve within the complex cannot access membrane-incorporated phosphoinositides due to steric constraints. We find further that the phosphoinositide-directed activities of both PIKfyve and Fig4 are regulated by protein-directed activities within the complex. PIKfyve autophosphorylation represses its lipid kinase activity and stimulates Fig4 lipid phosphatase activity. Further, Fig4 is also a protein phosphatase acting on PIKfyve to stimulate its lipid kinase activity, explaining why catalytically active Fig4 is required for maximal PI(3,5)P2 production by PIKfyve in vivo.
Collapse
Affiliation(s)
- Joshua A Lees
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - PeiQi Li
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Nikit Kumar
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Lois S Weisman
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Karin M Reinisch
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
| |
Collapse
|
10
|
Multi-model functionalization of disease-associated PTEN missense mutations identifies multiple molecular mechanisms underlying protein dysfunction. Nat Commun 2020; 11:2073. [PMID: 32350270 PMCID: PMC7190743 DOI: 10.1038/s41467-020-15943-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 04/03/2020] [Indexed: 01/16/2023] Open
Abstract
Functional variomics provides the foundation for personalized medicine by linking genetic variation to disease expression, outcome and treatment, yet its utility is dependent on appropriate assays to evaluate mutation impact on protein function. To fully assess the effects of 106 missense and nonsense variants of PTEN associated with autism spectrum disorder, somatic cancer and PTEN hamartoma syndrome (PHTS), we take a deep phenotypic profiling approach using 18 assays in 5 model systems spanning diverse cellular environments ranging from molecular function to neuronal morphogenesis and behavior. Variants inducing instability occur across the protein, resulting in partial-to-complete loss-of-function (LoF), which is well correlated across models. However, assays are selectively sensitive to variants located in substrate binding and catalytic domains, which exhibit complete LoF or dominant negativity independent of effects on stability. Our results indicate that full characterization of variant impact requires assays sensitive to instability and a range of protein functions. Mutations in PTEN have been associated with various human disease, including autism spectrum disorder (ASD) and cancer. Here, the authors assess the function of 106 PTEN variants in yeast, invertebrate models and cell culture and report that PTEN variants generally decrease protein stability.
Collapse
|
11
|
Ishii A, Kurokawa K, Hotta M, Yoshizaki S, Kurita M, Koyama A, Nakano A, Kimura Y. Role of Atg8 in the regulation of vacuolar membrane invagination. Sci Rep 2019; 9:14828. [PMID: 31616012 PMCID: PMC6794316 DOI: 10.1038/s41598-019-51254-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 09/26/2019] [Indexed: 01/23/2023] Open
Abstract
Cellular heat stress can cause damage, and significant changes, to a variety of cellular structures. When exposed to chronically high temperatures, yeast cells invaginate vacuolar membranes. In this study, we found that the expression of Atg8, an essential autophagy factor, is induced after chronic heat stress. In addition, without Atg8, vacuolar invaginations are induced conspicuously, beginning earlier and invaginating vacuoles more frequently after heat stress. Our results indicate that Atg8's invagination-suppressing functions do not require Atg8 lipidation, in contrast with autophagy, which requires Atg8 lipidation. Genetic analyses of vps24 and vps23 further suggest that full ESCRT machinery is necessary to form vacuolar invaginations irrespective of Atg8. In contrast, through a combined mutation with the vacuole BAR domain protein Ivy1, vacuoles show constitutively enhanced invaginated structures. Finally, we found that the atg8Δivy1Δ mutant is sensitive against agents targeting functions of the vacuole and/or plasma membrane (cell wall). Collectively, our findings revealed that Atg8 maintains vacuolar membrane homeostasis in an autophagy-independent function by coordinating with other cellular factors.
Collapse
Affiliation(s)
- Ayane Ishii
- Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, 422-8529, Japan
| | - Kazuo Kurokawa
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama, 351-0198, Japan
| | - Miyuu Hotta
- Department of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan
| | - Suzuka Yoshizaki
- Department of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan
| | - Maki Kurita
- Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, 422-8529, Japan
| | - Aya Koyama
- Department of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan
| | - Akihiko Nakano
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama, 351-0198, Japan
| | - Yoko Kimura
- Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, 422-8529, Japan. .,Department of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan.
| |
Collapse
|
12
|
Wang H, Lo WT, Haucke V. Phosphoinositide switches in endocytosis and in the endolysosomal system. Curr Opin Cell Biol 2019; 59:50-57. [DOI: 10.1016/j.ceb.2019.03.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 03/08/2019] [Accepted: 03/19/2019] [Indexed: 02/07/2023]
|
13
|
Miner GE, Sullivan KD, Guo A, Jones BC, Hurst LR, Ellis EC, Starr ML, Fratti RA. Phosphatidylinositol 3,5-bisphosphate regulates the transition between trans-SNARE complex formation and vacuole membrane fusion. Mol Biol Cell 2018; 30:201-208. [PMID: 30427760 PMCID: PMC6589561 DOI: 10.1091/mbc.e18-08-0505] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Phosphoinositides (PIs) regulate a myriad of cellular functions including membrane fusion, as exemplified by the yeast vacuole, which uses various PIs at different stages of fusion. In light of this, the effect of phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) on vacuole fusion remains unknown. PI(3,5)P2 is made by the PI3P 5-kinase Fab1 and has been characterized as a regulator of vacuole fission during hyperosmotic shock, where it interacts with the TRP Ca2+ channel Yvc1. Here we demonstrate that exogenously added dioctanoyl (C8) PI(3,5)P2 abolishes homotypic vacuole fusion. This effect was not linked to Yvc1, as fusion was equally affected using yvc1Δ vacuoles. Thus, the effects of C8-PI(3,5)P2 on fusion and fission operate through distinct mechanisms. Further testing showed that C8-PI(3,5)P2 inhibited vacuole fusion after trans-SNARE pairing. Although SNARE complex formation was unaffected, we found that C8-PI(3,5)P2 blocked outer leaflet lipid mixing. Overproduction of endogenous PI(3,5)P2 by the fab1T2250A hyperactive kinase mutant also inhibited the lipid mixing stage, bolstering the model in which PI(3,5)P2 inhibits fusion when present at elevated levels. Taken together, this work identifies a novel function for PI(3,5)P2 as a regulator of vacuolar fusion. Moreover, it suggests that this lipid acts as a molecular switch between fission and fusion.
Collapse
Affiliation(s)
- Gregory E Miner
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Katherine D Sullivan
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Annie Guo
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Brandon C Jones
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Logan R Hurst
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Ez C Ellis
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Matthew L Starr
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Rutilio A Fratti
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801.,Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| |
Collapse
|
14
|
Lipids and lipid domains of the yeast vacuole. Biochem Soc Trans 2018; 46:1047-1054. [PMID: 30242116 DOI: 10.1042/bst20180120] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 07/30/2018] [Accepted: 08/01/2018] [Indexed: 11/17/2022]
Abstract
The membrane raft has been a focus of intensive research for the past two decades. Liquid-ordered domains form in artificial liposomes containing sterol and saturated lipids, but their presence in living cell membranes has been controversial. The yeast vacuole is exceptional in that micron-sized raft-like domains form in the stationary phase and under several other conditions. The sterol content of the vacuole in the log phase is much lower than that of liposomes showing liquid-ordered domains, suggesting that sterols may need to be supplied to the vacuole for the raft-like domain formation. We will discuss how lipids and lipid domains are organized in the vacuolar membrane and examine whether evidence is strong enough to conclude that the observed micron-sized domains are rafts.
Collapse
|
15
|
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.
Collapse
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
| |
Collapse
|